JP4173797B2 - Optical disk device - Google Patents

Description

  The present invention relates to a technique for correcting an electrical offset generated in an electric circuit of an optical disc apparatus.

  When the optical disc apparatus writes and / or reads data, the optical disc apparatus irradiates a track of the optical disc with a laser beam to form a laser spot, receives the reflected light with a photodetector, and converts it into an electrical signal. In order to accurately follow the irradiation position of the laser beam to the information recording layer of the optical disc and the track on the layer, the optical disc apparatus has a servo signal (such as a tracking error signal or a focus error signal) indicating a tracking residual based on the electrical signal. Is generated, and feedback control of the irradiation position is performed.

  The servo signal generation circuit includes a large number of amplifiers. Since there is an electrical offset that is difficult to prevent completely in the amplifier, such an electrical offset is superimposed on the generated servo signal. If the irradiation position of the laser beam is controlled using such a servo signal, a tracking residual is generated and the recording / reproducing performance is deteriorated. Therefore, the conventional optical disc apparatus employs a measure of correcting the electrical offset in advance before writing and / or reading data.

  Furthermore, the optical disc apparatus described in Patent Document 1 corrects the electrical offset during data writing and / or reading. The reason is that the electrical offset has a characteristic that changes depending on the ambient temperature of the circuit, and it is necessary to perform an appropriate correction according to the change.

  FIG. 25 shows a functional block configuration of a conventional optical disc apparatus 250. The optical disc apparatus 250 operates as follows. That is, when the laser diode 2002 emits laser light and emits laser light, the laser light is converted into parallel light by the collimator lens 2003 and passes through the beam splitter 2004 to reach the objective lens 2005. The objective lens 2005 collects parallel light to form a laser spot on the information recording layer of the optical disc 2001, and converts the light (reflected light) reflected from the information recording layer into parallel light. The beam splitter 2004 directs the reflected light from the objective lens 2005 to the received light amount detection unit 2006. The received light amount detection unit 2006 receives the parallel light, and generates and outputs a light amount signal proportional to the received light amount. The TE signal generation unit 2007 generates and outputs a tracking error (TE) signal indicating a deviation between the irradiation position of the laser beam and the recording track center of the optical disc 2001 based on the light amount signal.

  On the other hand, when the header detection unit 2013 detects a header recorded in advance for each sector of the optical disc 2001 as a prepit based on the light amount signal and generates a header reproduction signal, the detection control unit 2008 holds the tracking signal hold, laser Non-emission control and TE signal offset detection are performed, and then laser emission and tracking signal hold release are performed. The detection control unit 2008 generates various control signals for performing these controls. Specifically, based on the header reproduction signal, the detection control unit 2008 controls the hold signal that controls the control signal generation unit 2009, the cutoff signal that controls the laser emission of the laser diode 2002, and the offset detection unit 2010. A detection control signal is output. When the hold signal output from the detection control unit 2008 instructs the hold, the control signal generation unit 2009 holds the tracking control signal. When the cutoff signal instructs the laser emission stop, the laser diode 2002 puts the laser in a non-emission state. When the detection control signal instructs offset detection, the offset detection unit 2010 detects the offset of the TE signal.

  The offset detection unit 2010 detects the offset amount of the electrical offset superimposed on the TE signal based on the detection control signal indicating the offset detection, and the offset correction unit 2011 represents the correction amount based on the offset amount. An offset correction signal is generated. The tracking control unit 2009 corrects the offset of the TE signal based on the calculated correction signal.

  The control signal generation unit 2009 corrects the TE signal based on the offset correction signal, and outputs a tracking control signal for causing the irradiation position of the laser light to follow the recording track of the optical disc 2001 according to the TE signal. The lens driving circuit 2012 changes the position of the objective lens 2005 according to the tracking control signal.

The optical disc apparatus 250 corrects the electrical offset of the TE signal every time a header is detected during a data read operation. This is the same during the write operation.
JP-A-5-62220

  In the conventional optical disk device, even during the data reading and writing operations, the laser is temporarily turned off to correct the electrical offset. Therefore, the data writing and reading to the optical disk must be interrupted during that time. This reduces the transfer rate from the optical disk device to the host computer or the like during reproduction, and decreases the transfer rate from the host computer or the like to the optical disk device during recording, making it difficult to secure the necessary transfer rate. In particular, in an optical disc apparatus capable of recording a TV program or the like on an optical disc and playing it back simultaneously, it is necessary to write and read data alternately and without interruption, so a higher transfer rate than before must be ensured. I must.

  Furthermore, with the recent increase in capacity of optical disks, the recording density of optical disks has increased, and higher servo accuracy is required. As a result, the optical disk apparatus needs to frequently correct the electrical offset. In this case, the time for interrupting the data writing and reading becomes longer, and it becomes more difficult to secure a high transfer rate.

  Increasing the capacity of the buffer memory of the optical disk apparatus can alleviate the above problem, but it is not a good idea because it increases the cost of the optical disk apparatus.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a technique for correcting an electrical offset without reducing the transfer rate.

An optical disc device according to the present invention is an optical disc device that performs at least one of data writing and reading with respect to an optical disc having an information recording layer, and includes a light source that emits light, a lens that converges the light, and the optical disc. A photodetector that detects the reflected light and outputs a reproduction signal, at least one blocking unit that outputs one of the reproduction signal and a predetermined reference signal, and a servo signal based on the output signal of the blocking unit A servo signal generation unit that generates the offset signal, and an offset detection unit that detects an offset generated in the servo signal generation unit as a first offset, the servo signal generation unit when a reference signal is output from the blocking unit time system and offset detector, the detected value of the first offset to handle the output value as the value of the first offset And sequentially a storage unit for storing a calculation unit for the second offset is generated by interpolation calculation based on the value of the first offset held in the storage unit, the first offset value or the first offset And a correction unit that corrects the servo signal based on the value of the second offset and the value of the second offset, and the calculation unit calculates the second offset based on a change rate of the stored value of the first offset. Generate .

  The optical disk device generates a sensor that measures the temperature of the servo signal generation unit, an update signal that indicates whether the correction value needs to be updated based on the measured temperature, and the last of the correction values The information processing apparatus may further include a determination unit that generates a detection signal indicating whether the first offset needs to be detected based on an elapsed time from the update time. When the detection signal indicates the detection of the first offset and the update signal indicates the update of the correction value, the offset detection unit detects the current first offset, and the correction unit The first offset value is output as a correction value.

  The optical disk device generates a sensor that measures the temperature of the servo signal generation unit, an update signal that indicates whether the correction value needs to be updated based on the measured temperature, and the last of the correction values And a determination unit that generates a detection signal indicating whether or not the first offset needs to be detected based on an elapsed time since the update. When the detection signal does not instruct the detection of the first offset and the update signal instructs to update the correction value, the calculation unit may derive the second offset.

  The optical disk device generates a sensor that measures the temperature of the servo signal generation unit, an update signal that indicates whether the correction value needs to be updated based on the measured temperature, and the last of the correction values And a determination unit that generates a detection signal indicating whether or not the first offset needs to be detected based on an elapsed time since the update. When the detection signal does not instruct the detection of the first offset and the update signal does not instruct the update of the correction value, the correction unit corrects the first servo signal based on the current correction value. May be.

  The optical disc apparatus further includes a detection control unit that generates the blocking signal that instructs whether or not the reproduction signal needs to be blocked. When the detection signal instructs the detection of the first offset, the detection control unit generates a blocking signal that instructs to block the reproduction signal, and based on the blocking signal, the blocking unit blocks the reproduction signal Then, a predetermined reference signal may be output.

  The optical disc apparatus further includes a detection control unit that generates the blocking signal that instructs whether or not the reproduction signal needs to be blocked. When the detection signal instructs the detection of the first offset, the detection control unit may generate a cutoff signal that instructs the cutoff of the reproduction signal, and the light source may stop emitting light based on the cutoff signal. .

  An optical disk device controls a lens driving unit that changes the position of the lens in at least one of a radial direction of the optical disk and a direction perpendicular to the optical disk based on a control signal, and generates the control signal based on the detection signal And a signal generation unit. When the detection signal instructs the detection of the first offset, the control signal generation unit may hold the value of the control signal.

  The optical disc apparatus further includes an amplifying unit that amplifies and outputs the reproduction signal. The at least one blocking unit includes a first blocking unit and a second blocking unit, and the first blocking unit receives one of the reproduction signal and a predetermined first reference signal based on a first blocking signal. The second cutoff unit outputs one of the output signal of the amplification unit and a predetermined second reference signal to the servo signal generation unit based on a second cutoff signal, and the offset detection unit The output value of the amplifying unit when the first reference signal is output from the blocking unit is further detected as the value of the third offset of the amplifying unit generated due to the electric circuit of the amplifying unit. The storage unit further stores a plurality of detected third offset values, and the calculation unit outputs one of a current third offset value and a fourth offset value as a correction value, and When the value of 4 offset is output May derive a value of said fourth offset based on a change rate of the stored values of the plurality of third offset.

  The optical disk device includes a first sensor that measures the temperature of the amplification unit, a second sensor that measures the temperature of the servo signal generation unit, and the measured temperature of the amplification unit and the temperature of the servo signal generation unit. Generating an update signal instructing whether or not the correction value needs to be updated, and whether or not the first offset and the third offset need to be detected based on an elapsed time from the last update of the correction value. And a determination unit that generates a detection signal indicating the above. When the detection signal indicates the detection of the third offset and the update signal indicates the update of the correction value, the offset detection unit detects the current third offset, and the correction unit The third offset may be output as a correction value.

  At each time of writing data to the optical disc and at the time of reading data from the optical disc, the offset detection unit detects a first offset, and the storage unit stores the values of the plurality of first offsets. The calculation unit may output the correction value.

  The servo signal may be at least one of a tracking error signal and a focus error signal.

  The determination unit may generate an update signal instructing to update the correction value when the measured change amount of the temperature exceeds a predetermined threshold.

  The optical disc apparatus further includes a time measurement unit that measures the elapsed time, and the determination unit may generate an update signal instructing the update of the correction value when the measured time exceeds a predetermined threshold value. Good.

  The optical disc apparatus further includes a buffer for storing the data. When the update signal instructs to update the correction value, the determination unit may generate a detection signal indicating whether or not the first offset needs to be detected based on the amount of information in the buffer.

  The optical disc apparatus further includes a temperature storage unit that stores a plurality of measured temperature values. The calculation unit may derive the second offset value based on the temperature value stored in the temperature storage unit and the plurality of first offset values.

  The temperature storage unit stores the temperature value at a timing at which each value of the first offset is stored in the storage unit, and the calculation unit includes a current value among the temperature values stored in the temperature storage unit. Two temperature values closest to the temperature value are identified, and the second offset value is derived based on the first offset value stored in the storage unit at the same timing as the identified temperature value. Also good.

An optical disk device control method according to the present invention is a method for controlling an optical disk device that performs at least one of writing and reading data to and from an optical disk having an information recording layer, the step of emitting light, and the convergence of the light Detecting the light reflected by the optical disc, outputting a reproduction signal, outputting one of the reproduction signal and a predetermined reference signal as an output signal, and servoing based on the output signal Generating a signal, detecting an offset superimposed on the servo signal as a first offset , treating the servo signal with respect to the reference signal as the first offset , and detecting a plurality of detected a step of time-sequentially stores the value of the first offset, the coercive in the storage unit A step of interpolating and generating a second offset based on the value of the first offset, and correcting the servo signal based on the value of the first offset or the value of the first offset and the value of the second offset And the step of correcting the servo signal generates the second offset based on a change rate of the stored value of the first offset .

  An optical disc apparatus according to the present invention performs at least one of data writing and reading on an optical disc having an information recording layer. An optical disc apparatus includes a light source that emits light, a lens that converges the light, and an optical head that detects light and outputs a reproduction signal, and is substantially perpendicular to the information recording layer based on a control signal. A lens driving unit that changes the position of the lens in any direction, and a control signal generation unit that generates the control signal, the control including an instruction to move the lens to a position where the reflected light from the optical disc is not received A control signal generation unit that generates a signal, a TE signal generation unit that generates a first tracking error signal based on the reproduction signal, an offset detection unit that detects an electrical offset generated in the TE signal generation unit, A second tracking error signal obtained by removing the electrical offset from the first tracking error signal based on the electrical offset; An offset correction unit to generate, and a stray light adjustment unit that detects a stray light signal corresponding to light irregularly reflected in the optical head based on the second tracking error signal and removes the stray light signal from the reproduction signal. ing.

  An optical disc apparatus according to the present invention performs at least one of data writing and reading on an optical disc having an information recording layer. The optical disk apparatus includes an optical head having a light source that emits light, a lens that converges the light on the optical disk, and a photodetector that detects reflected light from the optical disk and outputs a first reproduction signal; A level adjustment unit that generates a second reproduction signal having a level within a predetermined range based on the reproduction signal; and a TE signal generation unit that generates a first tracking error signal based on the second reproduction signal, A TE signal generation unit whose dynamic range is the predetermined range, an offset detection unit that detects an electrical offset generated in the TE signal generation unit, and the first tracking error signal based on the electrical offset, An offset correction unit that generates a second tracking error signal from which an electrical offset has been removed; and the second tracking error signal. A control signal generating unit that generates a control signal based on the signal, and a lens driving unit that drives the lens in a direction crossing the track based on the control signal and positions the light convergence position on the track And.

  The method of controlling an optical disc apparatus according to the present invention includes: emitting light; converging the light onto the optical disc; detecting reflected light from the optical disc and outputting a first reproduction signal; Generating a second reproduction signal having a level within a predetermined range based on the first reproduction signal; generating a first tracking error signal based on the second reproduction signal; and the first tracking error. Detecting a value of an electrical offset generated when generating a signal and superimposed on the first tracking error signal; and based on the value of the electrical offset, Generating a second tracking error signal from which a general offset is removed, and the second tracking error signal It comprises a step of generating a control signal Zui, and causing the position where the light converges on the basis of the control signal is positioned on the track.

  According to the control method, the step of detecting the electrical offset a plurality of times at a predetermined interval, the step of storing each value of the electrical offset, and the at least two values of the electrical offset, Estimating the value of the electrical offset superimposed on the first tracking error signal after detection of the electrical offset. The step of generating the second tracking error signal may generate the second tracking error signal based on the estimated value of the electrical offset.

  An optical disc apparatus according to the present invention performs at least one of data writing and reading on an optical disc having an information recording layer. An optical disc apparatus includes a light source that emits light, a lens that converges the light, and an optical head that detects light and outputs a reproduction signal, and is substantially perpendicular to the information recording layer based on a control signal. A lens driving unit that changes the position of the lens in any direction, and a control signal generation unit that generates the control signal, the control including an instruction to move the lens to a position where the reflected light from the optical disc is not received A control signal generation unit that generates a signal, an FE signal generation unit that generates a first focus error signal based on the reproduction signal, an offset detection unit that detects an electrical offset generated in the FE signal generation unit, Based on the electrical offset, a second focus error signal is generated by removing the electrical offset from the first focus error signal. An offset correction unit, and a stray light adjustment unit that detects a stray light signal corresponding to light irregularly reflected in the optical head based on the second focus error signal and removes the stray light signal from the reproduction signal. Yes.

  An optical disc apparatus according to the present invention performs at least one of data writing and reading on an optical disc having an information recording layer. The optical disk apparatus includes an optical head having a light source that emits light, a lens that converges the light on the optical disk, and a photodetector that detects reflected light from the optical disk and outputs a first reproduction signal; A level adjusting unit that generates a second reproduction signal having a level within a predetermined range based on the reproduction signal, and a focal position of the light in the direction perpendicular to the optical disc and the information recording based on the second reproduction signal An FE signal generation unit that generates a first focus error signal indicating a positional relationship with a layer, the FE signal generation unit having a dynamic range of the predetermined range, and an electrical offset generated in the FE signal generation unit Based on the detected offset detection unit and the electrical offset, the electrical offset is removed from the first focus error signal. An offset correction unit for generating a 2-focus error signal; a control signal generation unit for generating a control signal based on the second focus error signal; and driving the lens in a direction perpendicular to the optical disk based on the control signal And a lens driving unit for positioning the light convergence position on the information recording layer.

  The method of controlling an optical disc apparatus according to the present invention includes: emitting light; converging the light onto the optical disc; detecting reflected light from the optical disc and outputting a first reproduction signal; Generating a second reproduction signal having a level within a predetermined range based on a level of the first reproduction signal; generating a first focus error signal based on the second reproduction signal; Detecting a value of an electrical offset generated when generating a focus error signal and being superimposed on the first focus error signal; and, based on the value of the electrical offset, from the first focus error signal Generating a second focus error signal from which the electrical offset is removed, and based on the second focus error signal Generating a control signal, the position where the light converges on the basis of the control signal and a step of positioning on the information recording layer.

  According to the control method, the step of detecting the electrical offset a plurality of times at a predetermined interval, the step of storing each value of the electrical offset, and the at least two values of the electrical offset, Estimating the value of the electrical offset superimposed on the first focus error signal after detection of the electrical offset. The step of generating the second focus error signal may generate the second focus error signal based on the estimated value of the electrical offset.

  An optical disc apparatus according to the present invention performs at least one of data writing and reading on an optical disc having an information recording layer. An optical disk device substantially includes an optical head having a light source that emits light, a lens that converges the light, and a photodetector that detects light and outputs a first reproduction signal, and the information recording layer based on a control signal. A lens driving unit that changes the position of the lens in a direction perpendicular to the control unit, and a control signal generation unit that generates the control signal, including an instruction to move the lens to a position where the reflected light from the optical disc is not received A control signal generating unit that generates a first control signal and a second control signal including an instruction to move the lens to a position for receiving reflected light from the optical disc; and driving the lens based on the first control signal. While the unit is operating, a stray light signal corresponding to light irregularly reflected in the optical head is detected based on the first reproduction signal, and a record of the detected stray light signal is detected. And a stray light adjusting unit that holds a correction value corresponding to the level, and a level within a predetermined range based on the level of the first reproduction signal while the lens driving unit is operating based on the second control signal. A level adjustment unit that generates a second reproduction signal having a signal generation unit, and a signal generation unit that generates a first servo signal indicating a positional relationship between the focal position of the light and the optical disc based on the second reproduction signal. A signal generation unit whose dynamic range is the predetermined range, an offset detection unit for detecting an electrical offset generated in the signal generation unit, and the electrical signal from the first servo signal based on the electrical offset And an offset correction unit that generates a second servo signal from which the offset is removed. The stray light adjustment unit corrects the second servo signal based on the correction value.

  The optical disc apparatus of the present invention updates the correction value by holding the servo control and detecting the electrical offset during the servo control or by deriving the electrical offset without holding the servo offset. to correct. Thereby, the time during which the optical disc apparatus interrupts writing and reading of data can be shortened, and high-rate information transfer can be realized between the optical disc apparatus and the buffer memory.

(Embodiment 1)
FIG. 1 shows a functional block configuration of the optical disc apparatus 19 according to the present embodiment. The optical disk device 19 includes a lens driving circuit 7, an optical head 10, a TE generation chip 11, an optical disk controller (ODC) 12, and a sensor unit 13.

  The optical disk device 19 can write and read data to and from the optical disk 1 using laser light. When performing these operations, the optical disc apparatus 19 performs control so that the focal point of the laser beam is positioned on the information recording layer of the optical disc and the laser spot follows the recording track provided on the information recording layer. . This control is called servo control. In the figure, components for performing servo control according to the present embodiment are shown. Another example of servo control will be described as the second embodiment.

  The optical disk device is connected to a host computer (not shown) such as a PC and can be used as the optical disk drive. The user operates the optical disk apparatus by operating the host computer. Recording information and / or reproduction information is not transferred directly between the optical disc apparatus and the host computer, but is transferred via a buffer memory (not shown) built in the drive. For example, when data is written on an optical disk, the recording information transmitted from the host computer is temporarily stored in the buffer memory, and the drive reads the information stored in the buffer memory and records it on the optical disk. When information is reproduced from the optical disk, the information reproduced from the optical disk by the drive is temporarily stored in the buffer memory, and the host computer reads the information stored in the buffer memory. Although constituent elements for performing the writing process and the reading process are not shown in FIG. 1, since well-known members and processing procedures can be used, description thereof is omitted in this embodiment.

  The optical disc 1 in this specification is assumed to be a disc-shaped recording medium such as a CD, DVD-ROM, DVD-RAM, DVD-RW, DVD-R, + RW, + R, BD (Blu-Ray Disc), and the like. . Hereinafter, each component of the illustrated optical disk device 19 will be described.

  The lens drive circuit 7 generates and outputs a drive signal based on the tracking control signal, and changes the position of an objective lens 5 described later in the radial direction of the optical disc 1. For example, when the tracking control signal is held, the output of the drive signal immediately before the hold is continued, and when the hold is released, the drive signal corresponding to the tracking control signal is output. The lens drive circuit 7 can change the position of the objective lens 5 not only in the radial direction of the optical disc 1 but also in the direction perpendicular to the information recording layer of the optical disc 1. Since there is no particular problem, the description is omitted.

  The optical head 10 includes a laser diode 2, a collimator lens 3, a beam splitter 4, an objective lens 5, a received light amount detection unit 6, a first blocking unit 100, and an amplification unit 101.

  The laser diode 2 emits laser light. The wavelength of the laser light varies depending on the type of the optical disc 1. For example, when the optical disc 1 is a BD, the wavelength of the laser beam is about 405 nm. The collimating lens 3 converts the laser light emitted from the laser diode 2 into parallel light. The beam splitter 4 transmits the parallel light emitted from the collimating lens 3 toward the objective lens 5, and transmits the parallel light from the objective lens 5 (reflected light from the optical disc 1) in a direction in which the received light amount detection unit 6 is located. To separate. The objective lens 5 collects the parallel light transmitted through the collimating lens 3 and the beam splitter 4 to form a laser spot on the information recording layer of the optical disc 1. The objective lens 5 converts the light reflected by the information recording layer into parallel light and sends it to the beam splitter 4. The received light amount detection unit 6 receives the parallel light emitted from the beam splitter 4, generates a light amount signal corresponding to the received light amount, and outputs it. For example, the received light amount detector 6 is a photodetector that outputs a photocurrent proportional to the received light amount. This photocurrent signal is a signal obtained as a result of reading data on the optical disc 1, and is also referred to as a reproduction signal in this specification.

  The first cutoff unit 100 outputs a reference voltage when a first cutoff signal output from the detection control unit 108 described later is at a high level, and outputs a light amount signal output from the received light amount detection unit 6 when it is at a low level. Output as is. The amplifying unit 101 is an amplifier that amplifies and outputs a signal output from the first blocking unit 100. When the light amount signal is output as it is from the first blocking unit 100, the amplified signal is substantially a reproduction signal.

  The TE generation chip 11 includes a second blocking unit 102, a TE signal generation unit 103, and a low-pass filter 109. The TE generation chip 11 can be realized as a semiconductor integrated circuit, for example.

  The second cutoff unit 102 outputs a reference voltage when a second cutoff signal output from the detection control unit 108 described later is at a high level, and outputs a signal output from the amplification unit 101 as it is at a low level. .

  The TE signal generation unit 103 outputs a tracking error (TE) signal indicating a deviation between the laser light irradiation position and the recording track center of the optical disc 1 based on the signal output from the second blocking unit 102. .

  The low-pass filter 109 cuts off components above the frequency band necessary for tracking control from the TE signal output from the TE signal generation unit 103 and extracts frequency components below that frequency (cut-off frequency). For example, when the optical disc 1 is a BD and rotates at a normal speed (1 × speed), a frequency component of about 100 kHz or less is extracted. The low-pass filter 109 increases the cutoff frequency when a detection signal output from the situation determination unit 107 described later is at a high level (for example, about 500 kHz in the above-described BD example) and decreases when the detection signal is at a low level. (Eg, about 100 kHz in the BD example above).

  The low-pass filter 109 may be an analog filter or a digital filter as long as the cutoff frequency is variable. The TE generation chip 11 may be provided as a DSP on the ODC 12 described below, and in that case, the TE generation chip 11 and the ODC 12 do not have to be separated.

  The sensor unit 13 includes a first temperature detection unit 104 and a second temperature detection unit 105. These are specifically sensors. The first temperature detection unit 104 detects the temperature inside or around the amplification unit 101 and outputs a first temperature signal. The second temperature detection unit 105 detects the temperature inside or around the TE signal generation unit 103 and outputs a second temperature signal.

  An optical disc controller (ODC) 12 includes a temperature storage unit 106, a situation determination unit 107, a detection control unit 108, a control signal generation unit 110, an offset correction unit 111, an offset detection unit 112, and a detection. A value storage unit 113 and a correction value calculation unit 114 are included. The ODC 12 includes one or more digital signal processors (DSPs) and a volatile or nonvolatile memory. The DSP is a so-called computer, and functions of the above-described components can be realized by executing a computer program stored in a memory. If the computer program given to the DSP is changed, the ODC according to the second to fourth embodiments can be realized in addition to the optical disk device according to the present embodiment. Such a computer program is described according to the processing described in the flowchart of the drawing referred to in the description of each embodiment later. The function of each element will be described below.

  The temperature storage unit 106 receives values of a first temperature signal output from the first temperature detection unit 104 and a second temperature signal output from the second temperature detection unit 105 in accordance with a detection signal and an update signal described later. Remember.

  The situation determination unit 107 outputs an update signal and a detection signal according to the value of the first temperature signal, the value of the second temperature signal, and the value stored in the temperature storage unit 106. A more detailed configuration of the situation determination unit 107 and a detailed description of the update signal and the detection signal will be described later.

  The detection control unit 108 outputs a first cutoff signal, a second cutoff signal, and a detection control signal that are indicated in binary according to the detection signal.

  When the detection signal is at a low level, the control signal generation unit 110 outputs a tracking control signal for causing the irradiation position of the laser light to follow the recording track of the optical disc 1 according to the output signal of the offset correction unit 111. On the other hand, when the detection signal is at a high level, the value of the tracking control signal is held (fixed). The offset correction unit 111 corrects an electrical offset included in the output signal of the low pass filter 109. Specifically, the offset correction unit 111 subtracts the value of the output signal of the correction value calculation unit 114 from the value of the output signal of the low-pass filter 109 and outputs the result.

  When receiving the high-level detection control signal from the detection control unit 108, the offset detection unit 112 detects an electrical offset and outputs an offset signal.

  The detection value storage unit 113 stores the value of the offset signal output from the offset detection unit 112 according to the detection signal and the detection control signal from the detection control unit 108.

  The correction value calculation unit 114 reads the stored values from the detection value storage unit 113 and the temperature storage unit 106 in accordance with the update signal and the detection signal, calculates a correction value for electrical offset, and outputs a correction signal. . Further, the correction value calculation unit 114 holds the value of the correction signal in accordance with the update signal.

  Next, each component of the ODC 12 will be described in more detail.

  FIG. 2 shows a functional block configuration of the situation determination unit 107. The situation determination unit 107 includes a temperature change detection unit 200, a determination unit 201, and an elapsed time measurement unit 202.

  The temperature change detection unit 200 reads the value from the temperature storage unit 106, calculates the difference between the value of the first temperature signal output from the first temperature detection unit 104 and the value stored in the temperature storage unit 106, and One temperature change signal is output. The value of the first temperature change signal indicates the absolute value of the difference. The temperature change detection unit 200 calculates the difference between the value of the second temperature signal output from the second temperature detection unit 105 and the value stored in the address 2 (described later) of the temperature storage unit 106, and calculates the absolute value thereof. A second temperature change signal is output. The temperature storage unit 106 has a plurality of information storage areas. The region in which the temperature change detection unit 200 reads out the value will be described later.

  The determination unit 201 outputs a normal low level update signal, and when the value of the first temperature change signal or the second temperature change signal exceeds a predetermined threshold, the level of the update signal is set to a high level for a certain time. Further, the determination unit 201 outputs a detection signal according to the update signal and the elapsed time signal output from the elapsed time measurement unit 202. The update signal and the detection signal are binary pulse signals.

  The elapsed time measuring unit 202 measures an elapsed time from the rising edge of the pulse of the detection signal and outputs an elapsed time signal indicating the value. Each time the detection signal pulse rises, the value of the elapsed time signal is reset to zero.

  Next, the information storage area of the temperature storage unit 106 will be described, and then the operation of the situation determination unit 107 using the temperature storage unit 106 will be described.

  The temperature storage unit 106 has six information storage areas. Temporarily, the address for specifying the position of each information storage area is described as address 1, address 2, address 3, address 4, address 5, and address 6, respectively. Information stored in each area is determined in advance. Specifically, the value of the first temperature signal is stored in the area of address 1, the value of the second temperature signal is stored in the area of address 2, the value of the first temperature signal is stored in the areas of address 3 and address 4, The values of the second temperature signal are stored in the areas of address 5 and address 6.

  The reason why each of the first temperature signal and the second temperature signal is stored in three different areas is to update the stored values at different timings. Specifically, the stored value in the area of address 1 is controlled by the update signal, the stored value in the area of address 2 is controlled by the update signal, the stored value in the areas of addresses 3 and 4 is detected by the detection signal, The stored value of the area is controlled by the detection signal.

  Next, the operation timing of the temperature storage unit 106 and the situation determination unit 107 will be described with reference to FIG.

  FIG. 3 is a timing chart of signals related to the situation determination unit 107.

  The first temperature signal is sampled at the timing when the pulse of the update signal rises (broken line in the direction perpendicular to the time axis in the figure), and the value is stored in the address 1 area of the temperature storage unit 106. For reference, the value of the stored first temperature signal is indicated by a black dot (●).

  The first temperature change signal is a signal indicating an absolute value of a value obtained by subtracting a value stored in the address 1 area of the temperature storage unit 106 from the value of the first temperature signal. Note that the value of the first temperature change signal is zero because the value of the first temperature signal and the value stored in the address 1 area are always equal at the rising edge of the pulse of the update signal.

  The second temperature signal is sampled at the timing when the pulse of the update signal rises, and the value is stored in the address 2 area of the temperature storage unit 106. For reference, the value of the stored second temperature signal is indicated by a black dot (●).

  The second temperature change signal is a signal indicating the absolute value of a value obtained by subtracting the value stored in the address 2 area of the temperature storage unit 106 from the value of the second temperature signal. Note that the value of the second temperature change signal is zero because the value of the second temperature signal and the value stored in the address 2 area are always equal at the rising edge of the pulse of the update signal.

  The temperature storage unit 106 stores the value stored in the address 3 area in the address 4 area when the pulse of the detection signal rises, and then stores the value of the first temperature signal in the address 3 area. . Then, the value stored in the address 5 area is stored in the address 6 area, and then the second temperature signal value is stored in the address 5 area.

  The update signal is normally at a low level, and is set to a high level for a certain time when the value of either the first temperature change signal or the second temperature change signal exceeds a predetermined threshold. When the update signal is at a high level, the value of the temperature storage unit 106 is instructed to be updated. When the update signal is at a low level, the value of the temperature storage unit 106 is instructed to be retained (that is, not updated).

  The detection signal is also normally at a low level, and when the value of the elapsed time signal exceeds a predetermined threshold at the timing when the pulse of the update signal rises, the detection signal is set to a high level for a certain time. That is, the detection signal is a signal indicating a detection result as to whether or not an elapsed time from a previously reset time exceeds a predetermined threshold value. A high-level detection signal indicates that there is detection, and a low-level detection signal indicates that there is no detection. The falling edge of the detection signal pulse is simultaneously with the falling edge of the update signal pulse.

  The elapsed time signal is reset to zero corresponding to the rise of the pulse of the detection signal, and changes in value in proportion to the subsequent elapsed time. The figure shows an elapsed time signal that increases in proportion to the elapsed time. Based on the value of the elapsed time signal, the elapsed time from the time of reset can be specified.

  Still referring to FIG. 3, the relationship between the signals will be described. Each time one of the temperature inside or around the amplifying unit 101 and the temperature inside or around the TE signal generating unit 103 changes by a predetermined amount or more from the rising edge of the update signal, the update signal becomes high level for a certain time. At this time, if a predetermined time has elapsed since the rising edge of the detection signal, the detection signal is at a high level for a certain time.

  Attention is paid to the times t1, t2 and t3 shown in FIG. Time t3 indicates the current time, time t2 indicates the closest past time when viewed from the time t3, and time t1 indicates the past time closest to time t2.

  The value of the first temperature signal at time t2 is stored in the area of address 1 of the temperature storage unit 106. Similarly, the value of the second temperature signal at time t2 is in the area of address 2, the value of the first temperature signal at time t2 is in the area of address 3, and the first temperature signal at time t1 is in the area of address 4. In the area of address 5, the value of the second temperature signal at time t2 is stored, and in the area of address 6, the value of the second temperature signal at time t1 is stored. That is, each area of address 1 and address 2 stores the values of the first temperature signal and the second temperature signal when the update signal finally becomes high level regardless of the value of the detection signal. In the areas 3 and 5, the values of the first temperature signal and the second temperature signal when the update signal and the detection signal are both at the last high level are stored. In each area, the values of the first temperature signal and the second temperature signal when the update signal and the detection signal are both at the high level two times before are stored.

  Next, the detection control unit 108 of the ODC 12 will be described in detail. FIG. 4 shows a functional block configuration of the detection control unit 108. The detection control unit 108 includes a first cutoff control unit 400, a second cutoff control unit 401, and an offset detection control unit 402. All of these operate according to the elapsed time from the rising point of the detection signal from the situation determination unit 107.

  The first cutoff control unit 400 generates a first cutoff signal and outputs it to the first cutoff unit 100. The second cutoff control unit 401 generates a second cutoff signal and outputs it to the second cutoff unit 102. The offset detection control unit 402 generates a detection control signal and outputs it to the offset detection unit 112 and the detection value storage unit 113. Hereinafter, the details of these signals will be described with reference to FIG.

  FIG. 5 is a timing chart of signals related to the detection control unit 108. The detection signal is output from the determination unit 201 as described above with reference to FIG. The first cutoff signal rises after the rising edge of the detection signal pulse, and falls before the falling edge of the detection signal pulse. The second cutoff signal rises after the rise of the pulse of the first cutoff signal, and falls simultaneously with the fall of the pulse of the first cutoff signal. The detection control signal includes two pulse waveforms while the first cutoff signal is at a high level. The first pulse rises after the rising edge of the first cutoff signal pulse and falls simultaneously with the rising edge of the second cutoff signal pulse. The second pulse rises after the rise of the pulse of the second cutoff signal, and falls at the same time as the fall of the pulses of the first cutoff signal and the second cutoff signal.

  Next, the offset detection unit 112 will be described in detail. When the offset detection unit 112 receives a high-level detection control signal from the detection control unit 108, the offset detection unit 112 detects the value of the output signal of the low-pass filter 109. As will be described later, the signal output from the low-pass filter 109 at this time includes a signal component caused by an electrical offset. The offset detection unit 112 has a function of detecting the value.

  Next, the detected value storage unit 113 will be described in detail. The detection value storage unit 113 has five information storage areas. The address of each information storage area is described as address 7, address 8, address 9, address 10, and address 11, respectively. The detection value storage unit 113 detects how many times each pulse of the detection control signal is after the rise of the pulse of the detection signal, and the pulse of the detection control signal from the detection control unit 108 according to each pulse Stores the value of the offset signal output by the offset detector 112 when the signal falls. When the pulse of the detection control signal is the first pulse, the value of the offset signal when the pulse falls is stored in the information storage area of the address 11. When it is the second pulse, the value of the offset signal at the fall is stored in the information storage area of address 8. The detection value storage unit 113 further subtracts the value stored at the address 8 from the value stored at the address 11 and stores the result at the address 7. With this operation, the total value of the electrical offset generated in the amplification unit 101 when the detection signal is at the high level is stored in the address 7 area, and the detection signal is at the high level in the address 8 area. The value of the electrical offset generated in the TE signal generation unit 103 and the low-pass filter 109 at a certain time is stored.

  The detection value storage unit 113 stores the value stored at the address 7 at the address 9 and the value stored at the address 8 at the address 10 when the pulse of the detection signal rises.

  By the above operation, the address 7 and the address 8 of the detection value storage unit 113 are values including the electric offset generated in the amplification unit 101 when TE is updated and detected, respectively, and TE A value including an electrical offset generated by the signal generation unit 103 and the low-pass filter 109 is stored. Further, the address 9 and the address 10 each include a value including an electrical offset generated in the amplifier 101 when updated and detected two times before, and the TE signal generator 103 and the low-pass filter 109. The value including the electrical offset occurring in is stored. In addition, the address 11 stores a value including an electrical offset generated in the amplification unit 101, the TE signal generation unit 103, and the low-pass filter 109 at the last update and detection.

  Next, the correction value calculation unit 114 will be described in detail.

  FIG. 6 shows the relationship between the value stored in the temperature storage unit 106 and the value stored in the detection value storage unit 113, and the detection signal and the update signal. When calculating the correction value, the correction value calculator 114 calculates the value of the first temperature signal, the value of the second temperature signal, the value of the electrical offset generated in the amplifier 101, the TE signal generator 103, and the low-pass filter. The value of the electrical offset generated at 109 is required.

  Now, the time t6 indicates the current time, and among the rising edges of the detection signal, the time t3 indicates the past time closest to the time t6, and the time t1 indicates the past time closest to the time t3. Of the falling edges of the detection signal, time t4 indicates the closest past time as viewed from time t6, and time t2 indicates the past time closest to time t4. Furthermore, the time t5 indicates the closest past time when viewed from the time t6 among the rising edges of the update signal.

  In the area of address 4 of the temperature storage unit 106, the value (T10) of the first temperature signal at time t1 is stored. In the area of address 3, the value (T11) of the first temperature signal at time t3 is stored. Further, the area of address 1 stores the value (T12) of the first temperature signal at time t5.

  On the other hand, the value (T20) of the second temperature signal at time t1 is stored in the area of address 6 of the temperature storage unit 106. In the area of address 5, the value (T21) of the second temperature signal at time t3 is stored. In the area of address 2, the value (T22) of the second temperature signal at time t5 is stored.

  The electrical offset value (Os10) of the amplification unit 101 near time t2 is stored in the area of the address 9 in the detection value storage unit 113. In the area of address 7, the electrical offset value (Os11) of the amplifier 101 near time t4 is stored.

  A total value (Os20) of electrical offsets of the TE signal generation unit 103 and the low-pass filter 109 near time t2 is stored in the area of the address 10 of the detection value storage unit 113. The area of address 8 stores the total electrical offset value (Os21) of the TE signal generation unit 103 and the low-pass filter 109 near time t4.

  Next, a correction value calculation procedure performed in the correction value calculation unit 114 will be described. The correction value calculation unit 114 separately calculates the correction value for the electrical offset of the amplification unit 101 and the correction value for the total electrical offset of the TE signal generation unit 103 and the low-pass filter 109, and finally adds both. The total correction value. The correction value calculation unit 114 calculates the correction value after the detection signal and update signal pulses from the situation determination unit 107 fall.

  Here, the correction value newly calculated by the correction value calculation unit 114 for the amplification unit 101 is C1. A newly calculated correction value for the TE signal generation unit 103 and the low-pass filter 109 is C2. A correction value to be finally output is C.

  First, when the update signal is at a high level and the detection signal is also at a high level, the correction value C1 is Os11 and the correction value C2 is Os21. The correction value C that is finally output is (C1 + C2). That is, the electrical offset at that time is detected by the offset detection unit 112, and the correction value calculation unit 114 directly uses the value as a correction value.

  When the update signal is at the high level and the detection signal is at the low level, the correction value calculation unit 114 calculates the correction value C1 according to (Expression 1) and calculates the correction value C2 according to (Expression 2). .

(Formula 1) C1 = (Os11−Os10) × (T12−T11) / (T11−T10) + Os11

(Formula 2) C2 = (Os21−Os20) × (T22−T21) / (T21−T20) + Os21

  The correction value C to be finally output is (C1 + C2). That is, since the electrical offset at that time is not detected, the correction value calculation unit 114 estimates the current electrical offset value from the past value, and uses the value as the correction value. The estimation assumes that the change in the electrical offset with respect to the temperature change is linear, and calculates based on the rate of change. As the electrical offset to be used, the value detected last and twice before is adopted, and the temperature at the time of detection is also used.

  Next, the operation of the optical disc device 19 will be described with reference to FIG.

  FIG. 7 shows an operation procedure of the optical disc apparatus 19. First, in step S <b> 100, the first temperature detection unit 104 and the second temperature detection unit 105 detect the temperatures of the amplification unit 101 and the TE signal generation unit 103. In the next step S101, the situation determination unit 107 determines whether the temperature of either the amplification unit 101 or the TE signal generation unit 103 has changed by a predetermined value or more since the last offset correction value update. If the temperature has not changed by a predetermined value or more, the process returns to step S100, and if it has changed, the process proceeds to step S102. In step S102, the situation determination unit 107 further determines whether or not a predetermined time or more has elapsed since the previous detection of the electrical offset. If the predetermined time or more has elapsed, the process proceeds to step S103, and if the predetermined time or more has not elapsed, the process proceeds to step S104.

  In step S103, the offset is detected by the offset detector 112. Here, the offset detection process will be described with reference to FIGS. 1 and 5. First, when the situation determination unit 107 sets the detection signal to a high level, the control signal generation unit 110 holds the value of the tracking control signal immediately before or at that time. During the hold period, the lens driving circuit 7 outputs a driving signal for fixing the position of the objective lens 5. By fixing the position of the objective lens 5 with respect to the optical disc 1, the laser spot is fixed at a position immediately before holding in the radial direction of the optical disc 1.

  At the same time as the detection signal becomes high level, the low-pass filter 109 switches the cutoff frequency to a higher value. At this time, the control signal generator 110 holds the tracking control signal from the rise of the pulse of the detection signal to the rise of the pulse of the first cutoff signal. This hold period includes the time required for switching the frequency of the low-pass filter 109.

  After the low-pass filter 109 switches the cutoff frequency, when the detection control unit 108 sets the first cutoff signal to a high level, the first cutoff unit 100 switches the output signal to a reference signal having a predetermined reference voltage. In other words, the reproduction signal is short-circuited to the reference voltage and output. At this time, the value of the signal output from the low-pass filter 109 is the value of the electrical offset generated in the circuit from the input of the amplification unit 101 to the output of the low-pass filter 109. For example, when the reference voltage is Vr1 and the output of the low-pass filter 109 is Vo1, the offset detection unit 112 detects (Vo1−Vr1) as an electrical offset at a later-described timing. Vr1 is a preset value. For example, when Vr1 = 0, Vo1 itself can be detected as an electrical offset.

  The time required for the output signal of the low-pass filter 109 to settle to the electrical offset value depends on the higher cutoff frequency of the low-pass filter 109. The time from the rise of the first cutoff signal pulse to the rise of the first pulse of the detection control signal is designed to include this settling time.

  When the signal value output from the low-pass filter 109 is set to the value of the electrical offset, the detection control signal thereafter becomes a high level, and the offset detection unit 112 detects the value of the electrical offset. The detected value is stored in the detected value storage unit 113. The width of the first pulse of the detection control signal is designed to cover the time required for detection by the offset detector 112.

  When the detection of the electrical offset is finished, the second cutoff signal becomes high level, and the second cutoff unit 102 switches the output signal to a reference signal having a predetermined reference voltage. At this time, the value of the signal output from the low-pass filter 109 is the value of the electrical offset generated in the circuit from the input of the TE signal generation unit 103 to the output of the low-pass filter 109. For example, assuming that the reference voltage is Vr2 and the output of the low-pass filter 109 is Vo2, the offset detector 112 detects (Vo2−Vr2) as an electrical offset at a timing described later. Here, Vr2 is a preset value. For example, when Vr2 = 0, Vo2 itself can be detected as an electrical offset. The time from the rise of the pulse of the second cutoff signal to the rise of the second pulse of the detection control signal is designed to include the settling time of the signal output from the low-pass filter 109, and is detected from the rise of the pulse of the first cutoff signal. It is equal to the time until the rise of the first pulse of the control signal.

  When the value of the output signal of the low-pass filter 109 is settled, the detection control signal thereafter becomes high level again, and the offset detection unit 112 detects the value of the electrical offset. The detected value is stored in the detected value storage unit 113. The width of the second pulse of the detection control signal is designed to cover the time required for detection by the offset detector 112 and is equal to the width of the first pulse.

  When the detection of the electrical offset is finished, the detection control signal, the first cutoff signal, and the second cutoff signal become low level, and the received light amount detection unit 6 outputs signals output from the first cutoff unit 100 and the second cutoff unit 102, respectively. The light amount signal to be output and the signal output from the amplifying unit 101 are switched. Then, the value of the signal output from the low-pass filter 109 returns to a value corresponding to the light amount signal. The time required for recovery depends on the higher cutoff frequency of the low-pass filter 109. The time from the fall of the pulse of the first cutoff signal and the second cutoff signal to the fall of the detection signal pulse is designed to cover this recovery time.

  When the output signal of the low-pass filter 109 returns to a value corresponding to the light amount signal, the detection signal becomes low level and the cut-off frequency band of the low-pass filter 109 is switched to the lower one. Further, the hold signal becomes low level, and the hold of the tracking control signal is released. As a result, the laser spot formed at the laser irradiation position in the radial direction of the optical disc 1 follows the center of the recording track of the optical disc 1. As described above, an electrical offset is detected.

  Next, the process of step S104 will be described with reference to FIG. 7 again. In step S104, the correction value calculation unit 114 performs linear calculation to calculate the electrical offset at the current temperature based on the past temperature and the electrical offset value stored in the temperature storage unit 106 and the detected value storage unit 113. Derive a value.

  Finally, in step S105, the correction value is updated using the electrical offset value detected in step S103 or the electrical offset value derived in step S104. Thereafter, the process returns to step S100.

  The optical disk device 19 of the present embodiment updates the correction value by detecting the electrical offset by holding the tracking control during tracking control or by deriving the electrical offset without holding the tracking control. Correct the electrical offset. As a result, the frequency of interrupting the recording / reproducing operation of the optical disk device 19 can be reduced, and high-rate information transfer can be realized between the optical disk device 19 and the buffer memory.

  Further, when detecting the electrical offset, the low-pass filter 109 is switched to a higher cutoff frequency than before, so that the signal settling time can be shortened. Accordingly, the tracking control hold time can be shortened. When the hold is released, it is possible to reliably return to the tracking operation without causing a tracking error, and the offset can be corrected in a short time.

  Since the correction value is updated according to the temperature change of the circuit, the electrical offset can be corrected with high accuracy while following the temperature change. In particular, when calculating the current electrical offset value from the temperature and electrical offset values detected in the past, the calculation is based on the past temperature closest to the present in time and the change in the past electrical offset. Is done. Thereby, highly accurate correction can be performed.

  Further, by detecting an electrical offset only when a predetermined time or more has elapsed since the previous detection, the transfer rate of the optical disc device 19 (for example, the transfer rate between the optical disc device 19 and the buffer memory) is recorded in the data. And / or at a rate that does not inhibit regeneration.

  The optical disc device 19 detects an electrical offset of a series of electric circuits constituting a signal path inside the device, or does not detect an electrical offset, and detects the temperature and electric current detected in the past as a unit. The current electrical offset value is derived from the static offset value. Therefore, even when the temperature of each part of the electrical circuit is different, the electrical offset for each part can be calculated with high accuracy, and the electrical offset can be corrected with high accuracy. Specifically, since the signal immediately after detecting the amount of received light is short-circuited to the reference voltage and the external input to the electric circuit is cut off, only the electric offset of the circuit related to the processing of the light quantity signal can be selectively corrected. According to this correction, there is no significant influence on the processing of other signal systems. Further, since the servo signal is held, it is possible to return to the servo operation at a high speed after detecting the electrical offset. As a result, the time during which the optical disk device 19 interrupts writing and reading of data can be shortened, and high-rate information transfer can be realized between the optical disk device 19 and the buffer memory.

  In the present embodiment, an electric circuit that forms a signal path from the input to the output of the amplifier 101 and an electric circuit that forms a signal path from the input of the TE signal generator 103 to the output of the low-pass filter 109 are classified. The electrical offset is corrected. However, it is also possible to divide the signal path more finely and correct the electrical offset of the electric circuit in the section. Thereby, correction with higher accuracy can be realized. Conversely, without providing the second blocking unit 102, only the offset of the electric circuit constituting the signal path from the input of the amplification unit 101 to the output of the low-pass filter 109 may be corrected. As a result, the number of circuits can be reduced and the time required to detect the electrical offset can be shortened. Note that the electrical offset may be detected by switching the circuit so as to bypass the low-pass filter 109. Thereby, settling time is shortened more and it can return to a follow-up operation | movement reliably.

(Embodiment 2)
FIG. 8 shows a functional block configuration of the optical disc apparatus 29 according to the present embodiment. The use of the optical disk device 29 is the same as that of the optical disk device 19 according to the first embodiment.

  The optical disk device 29 includes a lens driving circuit 7, an optical head, a temperature detection unit 707, a reproduction control unit 705, a reproduction buffer 706, an FE generation chip 21, and an optical disk controller (ODC) 22. . For simplification of the description of the drawings, reference numerals to the optical head are omitted.

  Hereinafter, each functional block will be described. Of the elements constituting each functional block, description of the elements having the same functions as those of the optical disc device 19 (FIG. 1) according to the first embodiment is omitted.

  The lens driving circuit 7 moves the objective lens 5 in a direction perpendicular to the information recording layer of the optical disc 1 according to the focus control signal from the control signal generation unit 704. The lens driving circuit 7 can change the position of the objective lens 5 not only in the direction perpendicular to the information recording layer of the optical disc 1 but also in the radial direction of the optical disc 1. Since it is not, description is abbreviate | omitted.

  The optical head is provided with an amplification unit 700 in place of the first blocking unit 100 and the amplification unit 101 of the optical head 10 (FIG. 1). The laser diode 2 emits laser when the cutoff signal output from the detection control unit 710 is low level, and stops laser emission when the cutoff signal is high level. In FIG. 8, the laser diode 2 shows a configuration for directly receiving a cutoff signal from the detection control unit 710. However, for example, a laser drive circuit such as a laser drive circuit 1305 of FIG. 15 to be described later may be provided to control the current to the laser diode 2 based on the cutoff signal. Specifically, the laser drive circuit operates so that a current sufficient to perform laser emission is supplied to the laser diode 2 when the cutoff signal is at a low level, and no current is supplied when it is at a high level. Furthermore, the cutoff signal may be generated by a control signal generation unit 704 described later.

  The amplifying unit 700 switches the amplification factor between two values. One of the values is a value corresponding to the laser power at the time of recording, and the other is a value corresponding to the laser power at the time of reproduction. The amplifying unit 700 switches the amplification factor of the light amount signal in accordance with a setting signal from the setting control unit 715 and an amplification control signal from the detection control unit 710, which will be described later, so that the laser power differs between recording and reproduction. Even in this case, the amplitude of the FE signal can be kept constant. The amplification control signal takes three values: high level, center level, and low level. The amplification unit 700 sets the amplification factor according to the setting signal if the amplification control signal is at the central level, or according to the amplification control signal if the level is other than the central level. The amplification unit 700 switches to an amplification factor corresponding to recording when the setting signal is high level, and switches to an amplification factor corresponding to reproduction when the setting signal is low level. By operating in this way, as will be described later, even if the variation range of the light amount signal output from the received light amount detection unit 6 is different, the variation range of the signal input to the FE signal generation unit 701 can be made unchanged. it can.

  The reproduction control unit 705 reads out and outputs the data recorded on the optical disc 1 based on the light amount signal.

  The reproduction buffer 706 accumulates the data read by the reproduction control unit 705. Each data is aggregated to become one or more pieces of information. A host computer (not shown) reads information stored in the reproduction buffer 706 and performs subsequent reproduction processing. The reproduction information amount signal indicates the amount of information stored in the reproduction buffer 706.

  The temperature detector 707 detects the internal temperature of the optical disk device 29 and outputs a temperature signal.

  Based on the output signal from the amplification unit 700, the FE signal generation unit 701 of the FE generation chip 21 detects a deviation of the irradiation position of the laser beam from the information recording layer of the optical disc 1 to detect a focus error (FE). Output a signal.

  The low-pass filter 702 cuts off and outputs components in the FE signal that are higher than the frequency band necessary for focus control. The low-pass filter 702 increases the cutoff frequency when the detection signal is at a high level and decreases it when the detection signal is at a low level.

  Next, each component of the ODC 22 will be described.

  The offset correction unit 703 subtracts the value of the output signal of the correction value storage unit 711 from the value of the output signal of the low-pass filter 702 and outputs the result.

  When the detection signal is at a low level, the control signal generation unit 704 outputs a focus control signal according to the output signal of the offset correction unit 703. The focus control signal is used to cause the irradiation position of the laser light to follow the information recording layer of the optical disc 1. Further, when the detection signal is at a high level, the control signal generation unit 704 fixes the value of the focus control signal.

  The temperature storage unit 708 stores the value of the temperature signal according to the detection signal and the update signal.

  The situation determination unit 709 outputs a binary update signal according to the temperature signal and the value stored in the temperature storage unit 708. In addition, the situation determination unit 709 outputs a binary detection signal according to the value of the reproduction information amount signal.

  The detection control unit 710 outputs a cut-off signal, an amplification control signal, and a detection control signal that are expressed in binary according to the detection signal.

  The setting control unit 715 outputs a setting signal. The setting signal has a high level during recording and takes a low level during reproduction.

  The amplifying unit 700 amplifies and outputs the light amount signal, and switches the amplification factor according to the setting signal and the amplification control signal.

  When the offset detection unit 712 receives a high-level detection control signal, the offset detection unit 712 detects an electrical offset in the output signal of the low-pass filter 702 and outputs an offset signal.

  The detection value storage unit 713 stores the value of the offset signal based on the detection control signal and the detection signal.

  The correction value calculation unit 714 reads the value stored in the detection value storage unit 713 and the value stored in the temperature storage unit 708 in accordance with the update signal and the detection signal, calculates the correction value of the electrical offset, and calculates the correction signal. Is output.

  The correction value storage unit 711 stores the value of the correction signal and outputs the value. In addition, the value to be output is switched according to the setting signal from the setting control unit 715.

  The temperature storage unit 708 has three information storage areas, and stores the value of the temperature signal from the temperature detection unit 707. The address of each information storage area is described as address 1, address 2, and address 3, respectively. The update of the value stored in the area of address 1 is controlled by an update signal output from the situation determination unit 709. The update of the values stored in the areas of address 2 and address 3 is controlled by a detection signal output from status determination unit 709.

  Next, the situation determination unit 709 will be described in detail with reference to FIG. FIG. 9 shows a functional block configuration of the situation determination unit 709. The situation determination unit 709 includes a temperature change detection unit 800 and a determination unit 801. The temperature change detection unit 800 reads the value stored in the temperature storage unit 708 and calculates the difference between the value of the temperature signal output from the temperature detection unit 707 and the value stored in the address 1 area of the temperature storage unit 708. A temperature change signal indicating the absolute value is output. The determination unit 801 outputs an update signal indicated by a binary value in accordance with the temperature change signal output from the temperature change detection unit 800. Further, a detection signal indicated by a binary value is output in accordance with the update signal and the reproduction information amount signal output from the reproduction buffer 706.

  Next, the update signal and detection signal output from the situation determination unit 709 will be described in detail with reference to FIG. Here, the operation of each component of the temperature storage unit 708 and the situation determination unit 709 will also be described.

  FIG. 10 is a timing chart of signals related to the situation determination unit 709. When the value of the temperature change signal exceeds a predetermined threshold, the determination unit 801 sets the level of the update signal to a high level for a certain time. A high level update signal indicates that there is an update, and a low level update signal indicates that there is no update.

  The temperature storage unit 708 stores the value of the temperature signal when the update signal pulse rises in the address 1 area. In FIG. 10, the value to be stored is indicated by a black dot (●). The temperature change signal is obtained by subtracting the value stored in the address 1 area of the temperature storage unit 708 from the value of the temperature signal and taking the absolute value thereof. At the rising edge of the update signal, the value of the temperature signal is equal to the value stored in the address 1 area, so the value of the temperature change signal is zero.

  The detection signal is a binary signal output by the determination unit 801. When the value of the reproduction information amount signal is equal to or higher than a predetermined threshold at the timing when the pulse of the update signal rises, the detection signal is at a high level for a certain time, and when the value is equal to or lower than the predetermined threshold Goes low. The falling edge of the detection signal pulse is simultaneously with the falling edge of the update signal pulse. A high level detection signal indicates that there is detection, and a low level detection signal indicates that there is no detection.

  As shown in FIG. 10, when the temperature inside the optical disk device 29 changes by a predetermined value or more from the rising edge of the update signal, the update signal becomes high level for a certain time. At this time, if the reproduction buffer 706 stores a predetermined amount of information or more, the detection signal is at a high level for a certain time.

  When the detection signal rises to a high level, the temperature storage unit 708 stores the value stored in the address 2 area in the address 3 area, and then stores the temperature signal value in the address 2 area.

  Next, attention is paid to the times t1, t2, and t3 shown in FIG. Time t3 indicates the current time, time t2 indicates the closest past time when viewed from the time t3, and time t1 indicates the past time closest to time t2.

  The value of the temperature signal at time t2 is stored in each area of the address 1 and address 2 of the temperature storage unit 708, and the value of the temperature signal at time t1 is stored in the area of address 3. That is, the value of the temperature signal when the update signal finally becomes high level is stored in the area of address 1 regardless of the value of the detection signal, and both the update signal and detection signal are stored in the area of address 2 last. The value of the temperature signal when it becomes high level is stored, and the area of address 3 stores the value of the temperature signal when both the update signal and detection signal become high level two times before. Become.

  Next, the detection control unit 710 will be described. FIG. 11 shows a functional block configuration of the detection control unit 710. The detection control unit 710 includes an amplification control unit 900, a cutoff control unit 901, and an offset detection control unit 902. The amplification control unit 900 generates a ternary amplification control signal according to an elapsed time from when the detection signal from the situation determination unit 709 rises to a high level, and outputs the ternary amplification control signal to the amplification unit 700. The cutoff control unit 901 generates a cutoff signal and outputs it to the laser diode 2. The offset detection control unit 902 generates a detection control signal and outputs the detection control signal to the offset detection unit 712 and the detection value storage unit 713.

  Here, the timing of these signals will be described with reference to FIG. FIG. 12 shows a timing chart of signals related to the detection control unit 710. The cutoff signal rises after the rising edge of the detection signal pulse and falls before the falling edge of the detection signal pulse. The amplification control signal includes a positive pulse and a negative pulse once each while the cutoff signal is at a high level. The rising edge of the positive pulse is simultaneous with the rising edge of the pulse of the cutoff signal. The falling of the positive pulse and the falling of the negative pulse are simultaneous. The rising edge of the negative pulse coincides with the falling edge of the cutoff signal pulse. The detection control signal includes a pulse twice while the cutoff signal is at a high level. The first pulse rises after the rise of the cutoff signal pulse, and falls simultaneously with the fall of the positive pulse and the fall of the negative pulse of the amplification control signal. The second pulse rises after the fall of the positive pulse of the amplification control signal and the fall of the negative pulse, and falls simultaneously with the fall of the pulse of the cutoff signal.

  Next, the offset detection unit 712 will be described in detail. The offset detection unit 712 detects a signal value from the low-pass filter 702 when the detection control signal output from the detection control unit 710 is at a high level. As will be described later, the value of the signal output from the low-pass filter 702 during the first pulse of the detection control signal is the input of the amplification unit 700 when the amplification factor of the amplification unit 700 is switched to the one corresponding to the recording time. To the output of the low-pass filter 702. On the other hand, during the second pulse, the value of the signal output from the low-pass filter 702 is from the input of the amplification unit 700 to the output of the low-pass filter 702 when the amplification factor of the amplification unit 700 is switched to the one corresponding to the reproduction. The value of the electrical offset generated in the circuit between. The offset detection unit 712 has a function of detecting the value.

  Next, the detected value storage unit 713 will be described in detail. The detection value storage unit 713 has four information storage areas. The address of each information storage area is described as address 7, address 8, address 9, and address 10, respectively. The detection value storage unit 713 detects how many times each pulse of the detection control signal is after the detection signal pulse rises, and the pulse of the detection control signal from the detection control unit 710 is received according to each pulse. The value of the offset signal output by the offset detection unit 712 at the time of falling is stored. When the pulse of the detection control signal is the first pulse, the value of the offset signal when the pulse falls is stored in the information storage area of the address 7. When it is the second pulse, the value of the offset signal at the fall is stored in the information storage area of address 8. With this operation, the value of the electrical offset at the gain at the time of recording is stored in the area of address 7, and the value of the electrical offset at the gain at the time of reproduction is stored in the area of address 8.

  The detection value storage unit 713 stores the value stored at the address 7 at the address 9 and the value stored at the address 8 at the address 10 when the detection signal rises from the low level to the high level.

  As a result of the above operation, the values of the electrical offset with respect to the amplification factor at the time of recording and the amplification factor at the time of reproduction when the address 7 and the address 8 of the detection value storage unit 713 are updated and detected at the last are obtained. The address 9 and the address 10 each store the value of the electrical offset with respect to the gain at the time of recording and the gain at the time of reproduction when there was an update and detection two times before. become.

  Next, the correction value calculation unit 714 will be described in detail.

  FIG. 13 shows the relationship between the value stored in the temperature storage unit 708 and the value stored in the detection value storage unit 713 and the detection signal and update signal. When calculating the correction value, the correction value calculation unit 714 needs the value of the temperature signal, the value of the electrical offset with respect to the gain during recording, and the value of the electrical offset with respect to the gain during reproduction.

  Now, the time t6 indicates the current time, and among the rising edges of the detection signal, the time t3 indicates the past time closest to the time t6, and the time t1 indicates the past time closest to the time t3. Of the falling edges of the detection signal, time t4 indicates the closest past time as viewed from time t6, and time t2 indicates the past time closest to time t4. Furthermore, the time t5 indicates the closest past time when viewed from the time t6 among the rising edges of the update signal.

  In the area of address 3 of the temperature storage unit 708, the value (T0) of the temperature signal at time t1 is stored. In the area of address 2, the value (T1) of the temperature signal at time t3 is stored. Further, the area of address 1 stores the value (T2) of the first temperature signal at time t5.

  On the other hand, in the area of the address 9 in the detection value storage unit 713, an electrical offset value (Os10) with respect to the amplification factor at the time of recording near time t2 is stored. The area of address 7 stores an electrical offset value (Os11) with respect to the amplification factor at the time of recording near time t4.

  In addition, in the area of the address 10 of the detection value storage unit 713, an electrical offset value (Os20) with respect to the amplification factor at the time of reproduction near time t2 is stored. In the area of address 8, an electrical offset value (Os21) with respect to the amplification factor at the time of reproduction near time t4 is stored.

  Next, a correction value calculation procedure performed in the correction value calculation unit 714 will be described.

  The correction value calculation unit 714 separately calculates a correction value for the electrical offset with respect to the amplification factor during recording and a correction value for the electrical offset with respect to the amplification factor during reproduction. The correction value calculation unit 714 calculates a correction value after the detection signal and update signal pulses from the situation determination unit 709 fall.

  Here, a correction value newly calculated when the gain at the time of recording is employed is C1. Further, a correction value newly calculated when the amplification factor at the time of reproduction is adopted is assumed to be C2.

  First, when the update signal is at a high level and the detection signal is also at a high level, the correction value C1 is Os11 and the correction value C2 is Os21. That is, the current electrical offset is detected by the offset detection unit 712, and the correction value calculation unit 714 uses the value as it is as a correction value.

  When the update signal is at the high level and the detection signal is at the low level, the correction value calculation unit 714 calculates the correction value C1 by (Expression 3) and calculates the correction value C2 by (Expression 4). .

  (Formula 3) C1 = (Os11−Os10) × (T12−T11) / (T11−T10) + Os11

  (Formula 4) C2 = (Os21−Os20) × (T22−T21) / (T21−T20) + Os21

  At this time, the current electrical offset is not detected, and the correction value calculation unit 714 estimates the current electrical offset value from the past value, and uses that value as the correction value. For the estimation, the change of the electrical offset with respect to the temperature change is assumed to be linear, and calculation is performed from the electrical offset detected last and twice before and the temperature at that time.

  The correction value calculation unit 714 distinguishes between the case where the amplification factor of the amplification unit 700 is switched to the one corresponding to the recording and the case where the amplification factor is switched to the one corresponding to the reproduction, and uses the calculated correction value as a correction signal. Output. Further, the correction value storage unit 711 similarly distinguishes and stores the value of the correction signal.

  Next, the operation of the optical disk device 29 will be described with reference to FIG. FIG. 14 shows an operation procedure of the optical disk device 29.

  First, in step S200, the temperature detection unit 707 detects the temperature inside the optical disc apparatus. In the next step S201, the situation determination unit 709 determines whether or not the temperature inside the optical disc apparatus has changed by a predetermined value or more since the previous offset correction value update. If the temperature has not changed by a predetermined value or more, the process returns to step S200. If the temperature has changed, the process proceeds to step S202. In step S <b> 202, the situation determination unit 709 further determines whether or not a predetermined amount of information is stored in the reproduction buffer 706. If it is determined that it is stored, the process proceeds to step S203, and if it is determined that it is not stored, the process proceeds to step S204.

  In step S203, the offset is detected by the offset detector 712. Here, the offset detection process will be described with reference to FIGS. When the situation determination unit 709 sets the detection signal to a high level, the control signal generation unit 704 holds the value of the focus control signal immediately before or at that time. During the hold period, the lens driving circuit 7 outputs a driving signal for fixing the position of the objective lens 5. By fixing the position of the objective lens 5 with respect to the optical disc 1, the laser spot is fixed at a position immediately before the hold with respect to the irradiation position in the direction perpendicular to the information recording layer of the optical disc 1.

  At the same time as the detection signal goes high, the low pass filter 702 switches to a higher cutoff frequency. At this time, the control signal generation unit 704 holds the focus control signal from the rise of the pulse of the detection signal to the rise of the positive pulse of the amplification control signal and the pulse of the cutoff signal. This hold period includes the time required for switching the cutoff frequency of the low-pass filter 702.

  After the low-pass filter 702 switches the cutoff frequency, when the detection control unit 710 sets the amplification control signal to a high level, the amplification unit 700 switches the amplification factor to the one corresponding to the recording time. Further, the detection control unit 710 sets the cutoff signal to a high level and stops the laser emission of the laser diode 2. At this time, the value of the signal output from the low-pass filter 702 is an electrical offset value corresponding to the gain during recording. The principle of detection is the same as described in the first embodiment.

  The time required for the output signal of the low-pass filter 702 to settle to the electrical offset value depends on the higher cutoff frequency of the low-pass filter 702. The time from the rise of the positive pulse of the amplification control signal and the pulse of the cutoff signal to the rise of the first pulse of the detection control signal is designed to include this settling time.

  When the value of the output signal of the low-pass filter 702 is settled, the detection control signal becomes high level, and the offset detection unit 712 detects the value of the electrical offset. The detected value is stored in the detected value storage unit 713. The width of the first pulse of the detection control signal is designed to cover the time required for detection by the offset detector 712.

  When the detection of the electrical offset is completed, the amplification control signal becomes low level, and the amplification unit 700 switches the amplification factor to the one corresponding to the reproduction. At this time, the value of the signal output from the low-pass filter 702 is an electrical offset value corresponding to the amplification factor during reproduction. The detection principle of the electrical offset value is the same as that described in the first embodiment. The time from the fall of the negative pulse of the amplification control signal to the rise of the second pulse of the detection control signal is designed to include the settling time of the signal output from the low-pass filter 702, and the positive pulse of the amplification control signal and It is equal to the time from the rise of the pulse of the cutoff signal to the rise of the first pulse of the detection control signal.

  When the value of the signal output from the low-pass filter 702 is settled, the detection control signal thereafter becomes high level again, and the offset detection unit 712 detects the value of the electrical offset. The width of the second pulse of the detection control signal is designed to cover the time required for detection by the offset detector 712 and is equal to the width of the first pulse.

  When the detection of the electrical offset is completed, the detection control signal and the cutoff signal become low level, and the laser diode 2 emits laser light. At the same time, the amplification control signal becomes the center level. Then, the value of the output signal of the low-pass filter 702 returns to a value corresponding to the light amount signal. The time required for recovery depends on the higher cutoff frequency of the low-pass filter 702. The time from the fall of the second pulse of the cutoff signal and the detection control signal and the rise of the negative pulse of the amplification control signal to the fall of the detection signal pulse is designed to cover this recovery time. .

  When the output signal of the low-pass filter 702 returns to a value corresponding to the light amount signal, the detection signal becomes low level and the cut-off frequency band of the low-pass filter 702 is switched to the lower one. Further, the hold signal becomes low level, and the hold of the focus control signal is released. As a result, the focal position of the laser follows the information recording layer of the optical disc 1 in the direction perpendicular to the information recording layer of the optical disc 1. As described above, an electrical offset is detected.

  Next, the process of step S204 will be described with reference to FIG. 14 again. In step S204, the correction value calculation unit 714 calculates the value of the electrical offset at the current temperature by linear calculation based on the past temperature and the electrical offset value stored in the temperature storage unit 708 and the detected value storage unit 713. To derive.

  Finally, in step S205, the correction value is updated using the electrical offset value detected in step S203 or the electrical offset value derived in step S204. Thereafter, the process returns to step S200.

  The optical disk device 29 according to the present embodiment updates the correction value by detecting the electrical offset by holding the focus control during the focus control, or by deriving the electrical offset without holding the focus control. Correct the electrical offset. Thereby, the frequency at which the recording / reproducing operation of the optical disk device 29 is interrupted is reduced, and high-rate information transfer can be realized between the optical disk device 29 and the buffer memory.

  Further, according to the present embodiment, the correction value of the electrical offset of the circuit setting corresponding to each of the recording time and the reproducing time is calculated, and the correction value is switched corresponding to each circuit setting at the time of correction. Accurate correction is realized.

(Embodiment 3)
FIG. 15 shows a functional block configuration of the optical disc apparatus 39 according to the present embodiment. The use of the optical disc device 39 is the same as that of the optical disc device 19 according to the first embodiment.

  The optical disk device 39 includes a lens driving circuit 7, a laser driving circuit 1305, an optical head, a temperature detection unit 1307, a recording control unit 1314, a recording buffer 1315, a TE generation chip 31, and an optical disk controller (ODC) 32. And. For simplification of the description of the drawings, reference numerals to the optical head are omitted.

  Hereinafter, each functional block will be described. Of the elements constituting each functional block, description of the elements having the same functions as those of the optical disc device 19 (FIG. 1) according to the first embodiment is omitted.

  The laser drive circuit 1305 outputs a signal (for example, a current signal) for controlling the laser power for a predetermined period at a timing and intensity according to the cutoff signal output from the control signal generation unit 1304 and the recording signal. When the cutoff signal is at a high level, a signal is output so as to stop the laser emission.

  The optical head is provided with an amplifying unit 1300 in place of the first blocking unit 100 and the amplifying unit 101 of the optical head 10 (FIG. 1). The laser diode 2 emits laser light according to the output signal of the laser drive circuit 1305. However, as described with reference to FIG. 8 in the second embodiment, the detection control unit 1310 may generate and output a cutoff signal and control the operation of the laser diode 2 by the cutoff signal. That is, the laser diode 2 is controlled based on the cutoff signal, and laser light emission and stop are performed.

  The amplifying unit 1300 amplifies and outputs the light amount signal output from the received light amount detecting unit 6.

  The recording buffer 1315 acquires and records information to be recorded on the optical disc 1 from a host computer (not shown). The recording information amount signal indicates the amount of information stored in the recording buffer 1315.

  The recording control unit 1314 reads the information stored in the recording buffer 1315, converts it into a recording instruction signal for recording on the optical disc 1, and outputs it.

  The temperature detection unit 1307 detects the internal temperature of the optical disc device 39 and outputs a temperature signal.

  The TE signal generation unit 1301 of the TE generation chip 31 detects a deviation of the irradiation position of the laser beam from the recording track center of the optical disc 1 from the signal output from the amplification unit 1300, generates a TE (Tracking Error) signal, and outputs it. To do.

  The low-pass filter 1302 blocks and outputs a component of a frequency band or higher necessary for tracking control from the TE signal output from the TE signal generation unit 1301. Further, the cut-off frequency is increased when the detection signal output from the situation determination unit 1309 is at a high level, and is decreased when the detection signal is at a low level.

  Next, each component of the ODC 32 will be described.

  The offset correction unit 1303 subtracts the value of the correction signal output from the correction value calculation unit 1313 from the value of the signal output from the low-pass filter 1302 and outputs the result.

  When the detection signal is at a low level, the control signal generation unit 1304 outputs a tracking control signal for causing the laser light irradiation position to follow the recording track of the optical disc 1 in accordance with the signal output from the offset correction unit 1303. The control signal generation unit 1304 fixes the value of the tracking control signal when the detection signal is at a high level. The control signal generation unit 1304 receives a cutoff control signal indicated by a binary value from the detection control unit 1310 and generates a cutoff signal indicated by a binary value. Note that the binary level of the cutoff signal is determined according to the operating characteristics of the laser drive circuit 1305 that receives the cutoff signal. The timing of rising and falling of the cutoff control signal and the cutoff signal is the same.

  The time measurement unit 1306 measures the time from the falling edge of the pulse of the update signal indicated by the binary value output from the situation determination unit 1309 and outputs a time signal.

  The temperature storage unit 1308 stores the value of the temperature signal output from the temperature detection unit 1307 when the pulse of the detection signal indicated by the binary output from the situation determination unit 1309 falls.

  The situation determination unit 1309 outputs an update signal indicated by a binary value in accordance with the time signal output from the time measurement unit 1306. Also, a binary detection signal is output according to the recording information amount signal output from the recording buffer 1315 and the temperature signal output from the temperature detector 1307.

  The detection control unit 1310 outputs a cutoff control signal indicated by a binary value and a detection control signal according to the detection signal output from the situation determination unit 1309. Further, the detection control unit 1310 generates a recording signal based on the recording instruction signal from the recording control unit 1314.

  The offset detection unit 1311 detects an electrical offset included in the signal from the low-pass filter 1302 and outputs an offset signal when the detection control signal output from the detection control unit 1310 is at a high level.

  The detection value storage unit 1312 stores the value of the offset signal output by the offset detection unit 1311 when the pulse of the detection control signal output by the detection control unit 1310 falls.

  The correction value calculation unit 1313 reads the value stored in the detection value storage unit 1312 and the value stored in the temperature storage unit 1308 in accordance with the update signal and the detection signal from the situation determination unit 1309 and corrects the electrical offset. And a correction signal is output.

  Next, the situation determination unit 1309 will be described in detail with reference to FIG. FIG. 16 shows a functional block configuration of the situation determination unit 1309. The situation determination unit 1309 includes an update determination unit 1400, a temperature comparison unit 1401, and a detection determination unit 1402. The update determination unit 1400 outputs an update signal indicated by a binary value in accordance with the time signal output from the time measurement unit 1306. When the update signal is at a high level, it indicates that there is an update, and when it is at a low level, it indicates that there is no update.

  The temperature comparison unit 1401 differs from the temperature signal value output by the current temperature detection unit 1307 among the temperature values stored in the temperature storage unit 1308 when the pulse of the update signal output from the update determination unit 1400 rises. Detects whether there are two values within a predetermined value, and outputs a temperature comparison signal that is at a high level when there is no value, and at a low level when there is no value. The detection determination unit 1402 outputs a detection signal indicated by a binary value in accordance with the update signal output from the update determination unit 1400, the recording information amount signal output from the recording buffer 1315, and the temperature comparison signal output from the temperature comparison unit 1401. . A high level detection signal indicates that there is detection, and a low level detection signal indicates that there is no detection.

  Next, the update signal and detection signal output from the situation determination unit 1309 will be described in detail with reference to FIG. Here, the operation of each component of the time measurement unit 1306 and the situation determination unit 1309 will also be described.

  FIG. 17 is a timing chart of signals related to the situation determination unit 1309.

  The time signal is reset to zero when the pulse of the update signal falls and indicates the elapsed time thereafter. The update determination unit 1400 sets the update signal to a high level for a certain time when the value of the time signal exceeds a predetermined threshold. When the update signal is at a high level, it indicates that there is an update, and when it is at a low level, it indicates that there is no update.

  The temperature comparison signal is a signal output from the temperature comparison unit 1401 and indicates the presence or absence of a value whose difference from the current temperature value is within a predetermined value among the temperature values stored in the temperature storage unit 1308. Note that the falling edge of the temperature comparison signal pulse coincides with the falling edge of the update signal pulse.

  The detection signal is a binary signal output by the detection determination unit 1402, and when the value of the recorded information amount signal is equal to or lower than a predetermined value and the temperature comparison signal is at a high level in the vicinity of the timing when the pulse of the update signal rises. Becomes high level. At other times it is low. Note that the falling edge of the detection signal pulse coincides with the falling edge of the update signal pulse. When the detection signal is at a high level, it indicates that there is a detection, and when it is at a low level, it indicates that there is no detection.

  As shown in FIG. 17, the update signal has a pulse at regular intervals. The update signal has a difference from the value of the temperature signal currently output from the temperature detection unit 1307 among the temperature values stored in the temperature storage unit 1308 and the amount of information stored in the recording buffer 1315 is less than a predetermined value. When there are two values within a predetermined value, the signal becomes high level for a certain time.

  Next, the detection control unit 1310 will be described. FIG. 18 shows a functional block configuration of the detection control unit 1310. The detection control unit 1310 includes a cutoff control unit 1600 and an offset detection control unit 1601. The cutoff control unit 1600 generates a cutoff control signal according to the elapsed time from when the detection signal output from the situation determination unit 1309 rises to a high level, and outputs the cutoff control signal to the control signal generation unit 1304. The offset detection control unit 1601 generates a detection control signal and outputs the detection control signal to the offset detection unit 1311 and the detection value storage unit 1312. Here, the timing of these signals will be described with reference to FIG.

  FIG. 19 is a timing chart of signals related to the detection control unit 1310. The detection signal is output from the situation determination unit 1309 as described above with reference to FIG. The cutoff signal rises after the rising edge of the detection signal pulse and falls before the falling edge of the detection signal pulse. The detection control signal rises after the rising edge of the cutoff signal pulse and falls simultaneously with the cutoff signal pulse.

  Next, the temperature storage unit 1308 and the detected value storage unit 1312 will be described in detail.

  The temperature storage unit 1308 sequentially stores the value of the temperature signal output from the temperature detection unit 1307 in the information storage area each time the pulse of the detection signal falls. On the other hand, the detection value storage unit 1312 sequentially stores the value of the offset signal output from the offset detection unit 1311 in the information storage area each time the pulse of the detection control signal falls.

  In FIG. 19, the detection signal pulse fall timing and the detection control signal pulse fall timing are clearly different. However, this timing shift is sufficiently shorter than the time interval from the start to the end of the electrical offset correction, and can be approximated to be approximately the same time. That is, the value of the temperature signal stored in the temperature storage unit 1308 and the value of the offset signal stored in the detection value storage unit 1312 can be regarded as sampling values at substantially the same time. As a result, the value of the temperature signal and the value of the offset signal at the same time can be referred to by sequentially tracing the values stored in the temperature storage unit 1308 and the detected value storage unit 1312.

  Next, the correction value calculation unit 1313 will be described in detail with reference to FIGS. 15 and 17. The correction value calculation unit 1313 calculates a correction value after the pulse of the update signal falls.

  When the detection signal is also at a high level when the update signal is at a high level, the electrical offset stored in the detection value storage unit 1312 after the last pulse of the detection control signal falls, that is, the currently detected electrical offset The value of is used as a correction value as it is.

  When the update signal is at a high level and the detection signal is at a low level, the temperature storage unit 1308 outputs a temperature signal output from the temperature detection unit 1307 at the falling edge of the update signal from the stored temperature value. Search and read two values close to the value of. Next, the electrical offset value stored in the detected value storage unit 1312 is retrieved and read simultaneously with the time when the read temperature value is stored in the temperature storage unit 1308. Now, assume that the read temperature values are T0 and T1, and the electrical offset values corresponding to these temperature values are Os0 and Os1. Further, the current temperature signal value is T2, and the newly calculated correction value is C.

  The correction value calculation unit 1313 calculates the correction value C according to (Equation 5).

(Formula 5)
C = (Os1-Os0) * (T2-T1) / (T1-T0) + Os1

  At this time, the current electrical offset is not detected, the current electrical offset value is estimated from the past value, and the value is used as the correction value. For estimation, the change in the electrical offset with respect to the temperature change is linear from the temperature at the two times closest to the current temperature and the value of the electrical offset among the temperatures when the electrical offset was detected in the past. Calculate as

  Next, the operation of the optical disc device 39 will be described with reference to FIG. FIG. 20 shows an operation procedure of the optical disc device 39.

  First, in step S300, the situation determination unit 1309 determines whether or not a predetermined time has elapsed since the last offset correction value update. Step S300 is continuously performed until a predetermined time has elapsed. If it is determined that the predetermined time has elapsed, the process proceeds to step S301. In step S301, the status determination unit 1309 further determines whether the amount of information stored in the recording buffer 1315 is equal to or less than a predetermined value. When the value is equal to or smaller than the predetermined value, the process proceeds to step S302.

  In step S302, the offset is detected by the offset detector 1311. Here, the offset detection process will be described with reference to FIGS. 15 and 19. When the situation determination unit 1309 sets the detection signal to the high level, the control signal generation unit 1304 holds the value of the tracking control signal immediately before or at that time. During the hold period, the lens driving circuit 7 outputs a driving signal for fixing the position of the objective lens 5. By fixing the position of the objective lens 5 with respect to the optical disc 1, the laser spot is fixed at a position immediately before holding in the radial direction of the optical disc 1.

  At the same time as the detection signal goes high, the low-pass filter 1302 switches the cutoff frequency to a higher value. At this time, the control signal generation unit 1304 holds the tracking control signal from the rise of the pulse of the detection signal to the rise of the pulse of the cutoff signal. This hold period includes the time required for switching the frequency of the low-pass filter 1302.

  After the low-pass filter 1302 switches the cut-off frequency, the detection control unit 1310 sets the cut-off signal to a high level and stops laser light emission of the laser diode 2. At this time, the value of the signal output from the low-pass filter 1302 is the electrical offset value. The principle of detection is the same as that described in the first embodiment.

  The time required for the output signal of the low-pass filter 1302 to settle to the electrical offset value depends on the higher cutoff frequency of the low-pass filter 1302. The time from the rising edge of the cutoff signal pulse to the rising edge of the detection control signal pulse is designed to include this settling time.

  When the value of the output signal of the low-pass filter 1302 is set to the value of the electrical offset, the detection control signal becomes high level, and the offset detection unit 1311 detects the value of the electrical offset. The pulse width of the detection control signal is designed to cover the time required for detection by the offset detector 1311.

  When the detection of the electrical offset is completed, the detection control signal and the cutoff signal become low level, and the laser diode 2 emits laser light. Then, the value of the signal output from the low-pass filter 1302 returns to a value corresponding to the light amount signal. The time required for return depends on the higher cutoff frequency of the low-pass filter 1302. The time from the fall of the pulse of the cutoff signal and the detection control signal to the fall of the pulse of the detection signal is designed to cover this recovery time.

  When the output signal of the low-pass filter 1302 returns to a value corresponding to the light quantity signal, the detection signal becomes low level and the cutoff frequency of the low-pass filter 1302 is switched to the lower one. Further, the hold signal becomes low level, and the hold of the tracking control signal is released. As a result, the radial irradiation position of the optical disc 1 follows the recording track of the optical disc 1. As described above, an electrical offset is detected.

  Next, the process of step S303 will be described with reference to FIG. 20 again. In step S303, based on the past temperature stored in the temperature storage unit 1318 and the past electrical offset value stored in the detected value storage unit 1312, the value of the electrical offset at the current temperature is linearly calculated by linear calculation. Derived by calculation.

  Finally, in step S304, the correction value is updated using the electrical offset value detected in step S302 or the electrical offset value derived in step S303. Thereafter, the process returns to step S300.

  The optical disk device 39 of the present embodiment updates the correction value by detecting the electrical offset or by deriving the current electrical offset value based on the past temperature and the electrical offset value, Correct the electrical offset. As a result, the frequency of interrupting the recording / reproducing operation of the optical disc apparatus 39 is reduced, and high-rate information transfer can be realized between the optical disc apparatus 39 and the buffer memory at a high rate.

  Further, since the optical disk device 39 updates the correction value at regular time intervals, the transfer rate between the drive and the buffer memory can be kept above a certain level.

  Since the electrical offset is detected only when a predetermined amount or less of information is stored in the recording buffer, the transfer rate between the host computer and the buffer memory can be kept above a certain level. In this case, no problem occurs even if the transfer rate between the drive and the buffer memory is lowered during recording. Similarly, the amount of information recorded in the reproduction buffer may be detected, and detection of an electrical offset may be prohibited if the amount of information is equal to or less than a predetermined value. In this case, the transfer rate during reproduction can be kept above a certain level.

  In addition, when calculating the current electrical offset value from the temperature and electrical offset values detected in the past, the current electrical offset and temperature values accumulated and stored in the past detection are calculated. In order to find a value close to the value of the electrical offset and the temperature, it is no longer necessary to detect the electrical offset after the electrical offset has been detected a sufficient number of times. Therefore, high-rate information transfer can be realized between the drive and the buffer memory.

  In addition, when the temperature comparison signal output from the temperature comparison unit 1401 does not store a temperature value whose difference from the current temperature is within a predetermined range, an electrical offset with respect to the temperature is urged to prompt detection of the electrical offset. Even when the characteristic is not linear, high-accuracy correction can be realized.

  In addition, as described in the second embodiment, the optical disc apparatus according to the present embodiment calculates correction values for the case of circuit settings corresponding to each of recording and reproduction, and each circuit when performing correction. The correction value may be switched according to the setting. In this case, correction with higher accuracy can be realized.

  According to the second and third embodiments described above, when detecting the electrical offset, the laser emission is stopped and the external input to the circuit is shut off, so that the value of the electrical offset is not required to increase the circuit scale. It can be detected with high accuracy. Also, by holding the servo signal, it is possible to return to the servo operation at a high speed after detecting the electrical offset, shortening the time for interrupting the recording / reproducing operation of the drive and increasing the rate between the drive and the buffer memory. Information transfer can be realized.

  Further, since the electrical offset is detected only when a predetermined amount or more of information is stored in the reproduction buffer, the transfer rate between the host computer and the buffer memory can be kept at a certain level or more. In this case, no problem occurs even if the transfer rate between the drive and the buffer memory decreases during reproduction. Note that the amount of information stored in the recording buffer may be detected, and detection of an electrical offset may be prohibited when the amount of information is greater than or equal to a predetermined amount. Also at this time, the transfer rate at the time of recording can be kept above a certain level.

  As in the first embodiment, the circuit may be switched so as to bypass the low-pass filter, and the electrical offset may be detected, or the electrical offset may be corrected by dividing into electrical circuits that constitute the signal path. Good.

  Further, when the external input to the electric circuit is cut off, the signal immediately after detecting the amount of received light may be short-circuited to the reference voltage as described in the first embodiment. In this case, the external input can be cut off only in the signal circuit that requires correction for the electrical offset, and the value of the electrical offset can be detected with high accuracy without greatly affecting the processing of other signal systems.

  In the above-described embodiment, the configuration and operation of the optical disc apparatus for correcting the electrical offset with respect to the servo signal have been described. However, the optical disk apparatus can apply the same processing to all signals generated based on the light amount signal, not limited to those signals.

(Embodiment 4)
FIG. 21 shows a configuration of the optical disc apparatus according to the present embodiment. The optical disc apparatus according to the present embodiment includes a level adjustment unit 43 and a stray light adjustment unit 46, each of which has a higher level of a signal input to the TE signal generation unit 1301 and a signal input to the control signal generation unit 47. Adjust appropriately. As a result, the optical disc apparatus can perform servo control with higher accuracy.

  Hereinafter, the configuration of the optical disc apparatus will be described. The optical disk apparatus includes an optical head 40, a TE generation chip 41, an optical disk controller (ODC) 42, and a lens driving circuit 7.

  The optical head 40 includes a laser diode 2, a collimator lens 3, a beam splitter 4, an objective lens 5, a received light amount detection unit 6, and an amplification unit 1300. Since the function and operation of each component have already been described, description thereof will be omitted.

  It should be noted about the optical head 40 that the signal output from the optical head 40 includes a signal due to stray light. “Stray light” refers to irregular reflection components of laser light in the optical path between the collimating lens 3, the beam splitter 4, and the objective lens 5 of the optical head 40. For example, it is known that part of the laser light emitted from the collimating lens 3 toward the optical disc 1 is reflected by the objective lens 5 and returns to the collimating lens 3 again. The light returning in the direction of the collimating lens 3 is called stray light. The stray light is detected by the received light amount detector 6 together with the reflected light from the disk 1, and the detection signal is amplified by the amplifier 1300. Hereinafter, in this specification, a signal caused by stray light is referred to as a “stray light signal”, and a level of the signal is referred to as a “stray light offset”. The optical disk apparatus according to the present embodiment can remove the stray light signal by the stray light adjusting unit 46 described later.

  The TE generation chip 41 includes a level adjustment unit 43, a TE signal generation unit 1301, and a low pass filter 1302. Among these, since the TE signal generation unit 1301 and the low-pass filter 1302 are as described above, description thereof is omitted here. The TE generation chip 41 provided with the level adjusting unit 43 is produced as a semiconductor integrated circuit (IC), for example, and can be mounted on an optical disk device.

  The level adjustment unit 43 includes a level detection unit 43a and a level correction unit 43b, and adjusts and outputs the level of the amplified signal from the amplification unit 1300 by these. Hereinafter, the configuration and operation of the level adjusting unit 43 will be described in more detail with reference to FIGS. 22 (a) to 22 (d). The operating condition of the level adjusting unit 43, that is, the condition when the level adjusting unit 43 adjusts the level is that the laser diode 2 is lit and the optical disc apparatus is not performing the focus control operation and the tracking control operation. That is.

  The specification of the level adjustment unit 43 is determined in consideration of the relationship with the processing capability of the TE signal generation unit 1301. FIG. 22A shows a dynamic range D that can be processed by an amplifier (not shown) in the TE signal generation unit 1301. The dynamic range D is a range defined by the lower limit value Dmin and the upper limit value Dmax. The TE signal generation unit 1301 can generate a TE signal by performing normal processing on an internal signal having an amplitude within the dynamic range D. On the other hand, as shown in FIG. 22B, when the level of the internal signal exceeds the upper limit value Dmax, the TE signal generation unit 1301 cannot process a saturated portion equal to or higher than the upper limit value Dmax. Further, as shown in FIG. 22C, even when the level of the internal signal is smaller than the lower limit value Dmin, the TE signal generation unit 1301 cannot process a portion smaller than the lower limit value Dmin (so-called dead zone portion). .

  The level of the internal signal transmitted through the TE signal generation unit 1301 changes according to the level of the input signal, or the input signal is directly used as the internal signal of the TE signal generation unit 1301. Therefore, the level adjustment unit 43 adjusts the level of the input signal to the TE signal generation unit 1301 so that the internal signal of the TE signal generation unit 1301 falls within the dynamic range D shown in FIG. FIG. 22D shows the range of the input signal that falls within the dynamic range D of the TE signal generator 1301. When the level of the input signal (input voltage) is in the range of the reference voltage C ± A, the internal signal of the TE signal generator 1301 is in the range of FIG. FIG. 22D shows a signal whose amplitude is centered on a voltage higher than the reference voltage C by ΔC. Note that the reference voltage C and the width (± A) from the reference voltage C are determined from the maximum value and the minimum value of the known fluctuation range regarding the recording / reproducing operation of the optical disc apparatus.

  The level detection unit 43a of the level adjustment unit 43 detects the level of the signal input from the amplification unit 1300 over a certain period (for example, several signal cycles), and sends the detection result to the level correction unit 43b. Then, the level correction unit 43b calculates a deviation (ΔC) from the reference voltage C, and adds (−ΔC) to the level of the input signal to correct the signal level. As a result, the level correction unit 43b obtains a signal whose amplitude center matches the reference voltage C, and outputs the signal to the TE signal generation unit 1301. As a result of the above processing, the TE signal generation unit 1301 can operate normally and obtain an accurate TE signal. Note that even if the voltage at the center of the amplitude of the signal is matched with the reference voltage C, the amplitude may be larger than the amplitude A described above. In that case, the level correction unit 43b may further multiply the signal by a constant and correct the signal level so that the absolute values of the maximum and minimum values of the amplitude fall within C ± A.

  Note that changing the level of the input signal means giving an electrical offset (−ΔC) to the level of the input signal. This offset may be given as an arbitrary value or may be given as one of step-like values (−10 mV, −20 mV, etc.).

  According to the above-described processing, even if the dynamic range of the TE signal generation unit 1301 is set to be narrow, the TE signal generation unit 1301 can be operated normally, and power saving of the TE signal generation unit 1301 can be realized. Further, by narrowing the dynamic range of the TE signal generation unit 1301 that performs analog calculation, it is possible to improve the resolution of A / D conversion when a signal is input to the control signal generation unit 47 that performs digital calculation.

  Next, the ODC 42 will be described. The ODC 42 includes an offset detection unit 48, a detection value storage unit 44, a correction value calculation unit 45, an offset correction unit 1303, a stray light adjustment unit 46, and a control signal generation unit 47.

  Each function of the offset detection unit 48, the detection value storage unit 44, the correction value calculation unit 45, and the offset correction unit 1303 is the same as the function of the component having the same name illustrated in FIG. That is, the offset detection unit 48 detects an offset based on the signal output from the low-pass filter 1302, and the detection value storage unit 44 stores all the values of the offset signal output by the offset detection unit 48. The correction value calculation unit 45 reads the offset value stored in the detection value storage unit 44, calculates the correction value of the electrical offset, and outputs a correction signal. The offset correction unit 1303 corrects the output signal of the low-pass filter 1302 based on the correction value output from the correction value calculation unit 45. In the figure, only an offset detection unit, a detection value storage unit, a correction value calculation unit, and an offset correction unit provided in common with the optical disc apparatuses according to the first to third embodiments are illustrated.

  Through the above processing, the electrical offset caused by the amplifier or the like in the optical disc apparatus is corrected. Furthermore, according to this correction process, the level adjustment unit 43 can also correct an electrical offset intentionally given to the signal. For example, consider the case where the level correction unit 43b gives “−10 mV” of the step-like value. Assuming a complete correction is possible with an offset of “−13 mV”, the difference between −10 mV and −13 mV (−3 mV) is an electrical offset intentionally given to the signal. The offset correction unit 1303 can correct the electrical offset that has occurred so far, including this electrical offset.

  Next, the configuration and operation of the stray light adjustment unit 46 will be described. The stray light adjustment unit 46 includes a stray light detection unit 46 a and a stray light correction unit 46 b, and removes stray light caused by the optical path in the optical head 40. Under predetermined conditions, only a signal related to stray light is input to the stray light adjusting unit 46. The “predetermined conditions” are that the laser diode 2 is turned on, that the focus control operation and the tracking control operation are not performed, and that the received light amount detection unit 6 does not receive the reflected light from the optical disc 1. (For example, the objective lens 5 is sufficiently separated from the optical disc 1). In the present specification, this condition is set as a condition when the stray light adjusting unit 46 adjusts the stray light.

  In order to prevent the received light amount detection unit 6 from receiving the reflected light, the lens drive circuit 7 gives a predetermined drive signal to a focus actuator (not shown) physically connected to the lens 5, and the focus actuator Moves the objective lens 5 by a sufficient distance in a direction perpendicular to the optical disc 1 and away from the optical disc 1 in accordance with the drive signal. Such an operation is performed by the lens driving circuit 7 based on a control signal from the control signal generation unit 47. Further, when writing data to the information recording layer of the optical disc 1 and reading data from the information recording layer, a driving signal is output from the lens driving circuit 7 to the focus actuator so that the focus of the light beam is positioned on the information recording layer. .

  The lens driving circuit 7 can drive the lens 5 not only in the direction perpendicular to the optical disc 1 but also in the radial direction of the optical disc 1. At this time, the lens drive circuit 7 gives a drive signal to a tracking coil (not shown) physically connected to the lens 5, and the tracking coil drives the lens 5 in the radial direction of the optical disc 1 according to the drive signal. Thereby, it is possible to control so that the focal position of the light beam does not deviate from the recording track. The large radial movement of the optical head 40, which cannot be controlled by the tracking coil, moves the optical head to a predetermined recording track by moving a transfer table (not shown) for transferring the optical head 40. Control is performed so as to follow the recording track.

  When the stray light detection unit 46a detects and holds the level of the stray light signal, that is, the stray light offset, the stray light correction unit 46b can easily remove the stray light signal by subtracting the stray light offset from the output signal of the offset correction unit 1303. As a result, the control signal generation unit 47 can receive the signal output from the stray light correction unit 46b and generate a control signal free from the influence of stray light, thereby realizing highly accurate tracking control.

  Next, a series of processing procedures of the level correction operation and the stray light correction operation of the optical disc apparatus according to the present embodiment will be described with reference to FIG. FIG. 23 shows the procedure of the correction process of the optical disc apparatus according to the present embodiment. In step S401, the laser diode 2 is turned on and laser light is emitted. At this time, the optical disc apparatus does not perform the focus control operation and the tracking control operation, and moves the objective lens 5 in the focus direction to a position where the received light amount detection unit 6 does not receive the reflected light from the optical disc 1.

  In step S402, the level adjustment unit 43 performs level correction to adjust the level of the signal input to the TE signal generation unit 1301. In step S403, the offset correction unit 1303 performs electrical offset correction. In the next step S404, the stray light adjustment unit 46 detects the stray light offset and corrects the stray light.

  When the electrical offset and the stray light offset are corrected by the processing up to step S404, in the next step S405, the optical disc apparatus performs focus control to converge the light beam on the information recording layer of the optical disc 1, and in step S406, Tracking control is performed so that the light beam is correctly scanned onto the recording track of the optical disc 1. Thereafter, when an operation of recording data on the optical disc 1 or an operation of reading data from the optical disc 1 is started, step S407 is executed at predetermined time intervals.

  In step S407, the offset correction unit 1303 detects or estimates the electrical offset and corrects the electrical offset as necessary. In addition to the predetermined time interval, a temperature detection unit may be provided as in the optical disc apparatus according to the first embodiment, and step S407 may be executed when the predetermined temperature is reached.

  Note that the stray light correction in step S404 may be corrected only once when the optical disc apparatus is activated, unlike the correction of the electrical offset. This is because the influence of the temperature change after the start of operation on the generation state of stray light can be substantially ignored. When performing the stray light correction process, for example, as in the operation of the optical disc apparatus of the second embodiment, the optical disc apparatus may detect and correct the stray light offset by changing the settings during the data recording operation and the reproduction operation. . At this time, for example, the setting control unit 715 switches the recording light emission power and the reproduction light emission power to cause the laser diode 2 to emit light.

  The optical disk apparatus of FIG. 21 includes both the level adjustment unit 43 and the stray light adjustment unit 46, but only one of them may be provided. Since the operations of the level adjusting unit 43 and the stray light adjusting unit 46 are independent, each of the above-described objects can be achieved by operating each of the level adjusting unit 43 and the stray light adjusting unit 46 under the above-described conditions.

  The level adjustment unit 43 and / or the stray light adjustment unit 46 may be incorporated in the optical disc apparatus according to the first to third embodiments. For example, FIG. 24 shows a configuration of another optical disc apparatus in which the level adjusting unit 43 and the stray light adjusting unit 46 are provided in the optical disc apparatus according to the first embodiment. The level adjustment unit 43 is provided in the second blocking unit 102 and the TE signal generation unit 103 and adjusts the level of the signal input to the TE signal generation unit 103. Further, the stray light adjustment unit 46 is provided between the offset correction unit 111 and the control signal generation unit 110, and realizes highly accurate tracking control and focus control. Further, when the level adjusting unit is provided in the optical disc apparatus according to the second embodiment of the present invention, for example, the level adjusting unit is arranged between the amplifying unit 700 and the FE signal generating unit 701, and the level adjusting unit uses the FE signal. The level of the signal input to the generation unit 701 may be adjusted. As a result, the FE signal generation unit 701 operates normally and an accurate FE signal can be obtained. Furthermore, the above-described advantages associated with reducing the dynamic range of the FE signal generation unit 701 can be obtained.

  In addition, it is also possible to use a combination of two or more of the first to third embodiments in one data processing device. For example, by combining the processes according to the first and second embodiments, the electrical offset superimposed on each signal can be separately corrected for both the tracking error signal and the focus error signal.

  The optical disk apparatus according to the first to fourth embodiments has been described above. The optical disc apparatus according to each embodiment includes a method for shutting off an external input when detecting an electrical offset, an electrical offset separation for each part of the circuit, a setting corresponding to recording and reproduction, a method for calculating a correction value, and a correction value. May be different from each other in a situation where the current offset is updated and a situation where an electrical offset is detected. However, it is possible to realize high-rate information transfer and more accurate offset correction, level correction, and stray light correction by freely combining operating conditions such as these methods and setting contents. As a result, the quality of the servo signal is improved, and highly accurate servo control can be realized.

  In the present specification, tracking control and focus error control have been described as examples of servo control. The TE / FE signal, the FE / TE generation chip, and the TE / FE signal generation unit in the specification and the drawings can be summarized as a servo signal, a servo signal generation chip, a servo signal generation circuit, and the like, respectively.

  According to the present invention, when the electrical offset is corrected, the case where the electrical offset is detected and the case where the current electrical offset value is calculated from the past temperature and the electrical offset value are provided. It is possible to reduce the frequency of interrupting the recording / reproducing operation of the apparatus and realize high-rate information transfer between the optical disk apparatus and the buffer memory. Such an optical disk device is applicable to any optical disk device that reads and / or writes data to, for example, a CD, DVD-ROM, DVD-RAM, DVD-RW, DVD-R, + RW, + R, and BD. can do.

1 is a block diagram of an optical disc device according to Embodiment 1. FIG. 4 is a block diagram of a situation determination unit 107. FIG. 7 is a timing chart of signals related to the situation determination unit 107. 3 is a block diagram of a detection control unit 108. FIG. 4 is a timing chart of signals related to the detection control unit 108. It is a figure which shows the relationship between the value memorize | stored in the temperature memory | storage part, the value memorize | stored in the detected value memory | storage part 113, and a detection signal and an update signal. 4 is a flowchart showing an operation procedure of the optical disc device 19. 6 is a block diagram of an optical disc apparatus according to Embodiment 2. FIG. 6 is a block diagram of a situation determination unit 709. FIG. 7 is a timing chart of signals related to a situation determination unit 709. 3 is a block diagram of a detection control unit 710. FIG. 7 is a timing chart of signals related to a detection control unit 710. It is a figure which shows the relationship between the value memorize | stored in the temperature memory | storage part 708, the value memorize | stored in the detected value memory | storage part 713, and a detection signal and an update signal. 4 is a flowchart showing a procedure of an operation of the optical disc device 29. 6 is a block diagram of an optical disc device according to Embodiment 3. FIG. 6 is a block diagram of a situation determination unit 1309. FIG. 10 is a timing chart of signals related to a situation determination unit 1309. 5 is a block diagram of a detection control unit 1310. FIG. 10 is a timing chart of signals related to the detection control unit 1310. 5 is a flowchart showing a procedure of operation of the optical disc device 39. FIG. 6 is a block diagram of an optical disc device according to a fourth embodiment. (A) is a figure which shows the dynamic range D which the amplifier in TE signal generation part 1301 can process, (b) is a figure which shows the state in which the level of an internal signal exceeds upper limit Dmax, (c ) Is a diagram illustrating a state in which the level of the internal signal is smaller than the lower limit value Dmin, and (d) is a diagram illustrating a range of an input signal that falls within the dynamic range D of the TE signal generation unit 1301. 14 is a flowchart illustrating a procedure of correction processing of the optical disc device according to the fourth embodiment. FIG. 2 is a diagram illustrating a configuration of an optical disc apparatus in which a level adjustment unit 43 and a stray light adjustment unit 46 are provided in the optical disc apparatus according to the first embodiment. It is a block diagram of the conventional optical disk apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical disk 2 Laser diode 3 Collimating lens 4 Beam splitter 5 Objective lens 6 Light reception amount detection part 7 Lens drive circuit 10 Optical head 11 TE generation chip 12 Optical disk controller 13 Sensor part 40 Optical head 41 TE generation chip 42 Optical disk controller 43 Level adjustment part 43a level detection unit 43b level correction unit 44 detection value storage unit 45 correction value calculation unit 46 stray light adjustment unit 46a stray light detection unit 46b stray light correction unit 47 control signal generation unit 100 first blocking unit 101 amplifying unit 102 second blocking unit 103 TE Signal generation unit 104 First temperature detection unit 105 Second temperature detection unit 106 Temperature storage unit 107 Situation determination unit 108 Detection control unit 109 Low-pass filter 110 Control signal generation unit 111 Offset correction unit 112 Offset detection unit 13 detection value storage unit 114 correction value calculation unit

Claims (17)

An optical disc apparatus that performs at least one of data writing and reading with respect to an optical disc having an information recording layer,
A light source that emits light;
A lens for converging the light;
A photodetector that detects the light reflected by the optical disc and outputs a reproduction signal;
At least one blocking unit that outputs one of the reproduction signal and a predetermined reference signal;
A servo signal generation unit that generates a servo signal based on an output signal of the blocking unit;
An offset detection unit that detects an offset generated in the servo signal generation unit as a first offset, and outputs an output value of the servo signal generation unit when the reference signal is output from the blocking unit as the first offset An offset detection unit treated as a value,
A storage unit for sequentially storing the detected value of the first offset in time series;
A calculation unit that generates a second offset by interpolation based on the value of the first offset held in the storage unit;
A correction unit that corrects the servo signal based on the first offset value or the first offset value and the second offset value;
The said calculating part is an optical disk apparatus which produces | generates a said 2nd offset based on the change rate of the value of the stored said 1st offset. A sensor for measuring the temperature of the servo signal generator;
An update signal that indicates whether the correction value needs to be updated is generated based on the measured temperature, and the first offset needs to be detected based on an elapsed time since the last update of the correction value. A determination unit that generates a detection signal indicating NO, and when the detection signal instructs the detection of the first offset and the update signal instructs the update of the correction value, the offset detection unit includes: The optical disc apparatus according to claim 1, wherein a current first offset is detected, and the correction unit outputs the current first offset value as a correction value. A sensor for measuring the temperature of the servo signal generator;
An update signal that indicates whether the correction value needs to be updated is generated based on the measured temperature, and the first offset needs to be detected based on an elapsed time since the last update of the correction value. A determination unit that generates a detection signal indicating NO, and when the detection signal does not instruct the detection of the first offset and the update signal instructs to update the correction value, The optical disc apparatus according to claim 1, wherein the second offset is derived. A sensor for measuring the temperature of the servo signal generator;
An update signal that indicates whether the correction value needs to be updated is generated based on the measured temperature, and the first offset needs to be detected based on an elapsed time since the last update of the correction value. And a determination unit that generates a detection signal indicating NO, and when the detection signal does not instruct detection of the first offset and the update signal does not instruct update of the correction value, the correction unit includes: The optical disk apparatus according to claim 1, wherein the servo signal is corrected based on a current correction value. A detection control unit that generates the blocking signal that instructs whether or not to block the reproduction signal;
When the detection signal instructs detection of the first offset, the detection control unit generates a blocking signal that instructs blocking of the reproduction signal;
The optical disc apparatus according to claim 2, wherein the blocking unit blocks the reproduction signal and outputs a predetermined reference signal based on the blocking signal. A detection control unit that generates the blocking signal that instructs whether or not to block the reproduction signal;
When the detection signal instructs detection of the first offset, the detection control unit generates a blocking signal that instructs blocking of the reproduction signal;
The optical disc apparatus according to claim 2, wherein the light source stops emitting light based on the blocking signal. A lens driving unit that changes the position of the lens in at least one of a radial direction of the optical disc and a direction perpendicular to the optical disc based on a control signal;
A control signal generation unit that generates the control signal based on the detection signal; and
The optical disc apparatus according to claim 2, wherein when the detection signal instructs detection of the first offset, the control signal generation unit holds the value of the control signal. An amplifying unit for amplifying and outputting the reproduction signal;
The at least one blocking unit includes a first blocking unit and a second blocking unit, and the first blocking unit receives one of the reproduction signal and a predetermined first reference signal based on a first blocking signal. Outputting to the amplifying unit, the second blocking unit outputs one of the output signal of the amplifying unit and a predetermined second reference signal to the servo signal generating unit based on a second blocking signal;
The offset detection unit generates an output value of the amplifying unit when the first reference signal is output from the blocking unit due to a third offset of the amplifying unit generated due to an electric circuit of the amplifying unit. Detect further as a value,
The storage unit further stores a plurality of detected third offset values,
The calculation unit outputs one of the current third offset value and the fourth offset value as a correction value, and when outputting the fourth offset value, the stored third offset values The optical disc apparatus according to claim 1, wherein a value of the fourth offset is derived based on a change rate of the optical disc. A first sensor for measuring the temperature of the amplification unit;
A second sensor for measuring the temperature of the servo signal generator;
Based on the measured temperature of the amplification unit and the temperature of the servo signal generation unit, an update signal that indicates whether or not the correction value needs to be updated is generated, and an elapsed time since the last update of the correction value And a determination unit that generates a detection signal indicating whether or not the first offset and the third offset need to be detected, wherein the detection signal instructs the detection of the third offset, and the update 9. The optical disc according to claim 8, wherein when the signal instructs to update the correction value, the offset detection unit detects a current third offset, and the correction unit outputs the current third offset as a correction value. apparatus. At the time of writing data to the optical disc and at the time of reading data from the optical disc,
The optical disc apparatus according to claim 1, wherein the offset detection unit detects a first offset, the storage unit stores values of the plurality of first offsets, and the calculation unit outputs the correction value.   The optical disk apparatus according to claim 1, wherein the servo signal is at least one of a tracking error signal and a focus error signal.   The optical disc apparatus according to claim 2, wherein the determination unit generates an update signal instructing to update the correction value when the measured change amount of the temperature exceeds a predetermined threshold value. A time measurement unit for measuring the elapsed time;
The optical disc apparatus according to claim 2, wherein the determination unit generates an update signal instructing to update the correction value when the measured time exceeds a predetermined threshold value. A buffer for storing the data;
The said determination part produces | generates the detection signal which shows the necessity of the detection of the said 1st offset based on the information content in the said buffer, when the said update signal instruct | indicates the update of the said correction value. The optical disk device described. A temperature storage unit for storing a plurality of measured temperature values;
The optical disk apparatus according to claim 2, wherein the calculation unit derives the second offset value based on the temperature value stored in the temperature storage unit and the plurality of first offset values. The temperature storage unit stores the temperature value at a timing at which each value of the first offset is stored in the storage unit,
The calculation unit specifies two temperature values closest to the current temperature value among the temperature values stored in the temperature storage unit, and is stored in the storage unit at the same timing as the specified temperature value. The optical disc apparatus according to claim 15, wherein the second offset value is derived based on the first offset value. A method of controlling an optical disc apparatus that performs at least one of writing and reading of data to and from an optical disc having an information recording layer,
Emitting light;
Converging the light; and
Detecting the light reflected by the optical disc and outputting a reproduction signal;
Outputting one of the reproduction signal and a predetermined reference signal as an output signal;
Generating a servo signal based on the output signal;
Detecting an offset superimposed on the servo signal as a first offset, and treating the servo signal with respect to the reference signal as the first offset;
Storing the detected values of the plurality of first offsets sequentially in time series;
A step of interpolating and generating a second offset based on the value of the first offset held in the storage unit; and the value of the first offset or the value of the first offset and the value of the second offset Correcting the servo signal; and
The step of correcting the servo signal is a control method for generating the second offset based on a change rate of the stored value of the first offset.

Images