JP6180347B2 - Optical disc playback apparatus and focus pull-in control method - Google Patents

Description

  The present invention relates to an optical disc reproducing apparatus having a function of optically reading and reproducing data stored in a disc-shaped storage medium, and more particularly to a focus pull-in process when the focus is lost.

  The optical disk reproducing device includes an optical pickup for optically reading data recorded in a spiral shape on a recording medium (hereinafter referred to as an optical disk) such as a CD, a DVD, or a blue disk. The optical pickup includes a light emitting element that irradiates light onto a recording surface of an optical disc, an objective lens that collects light reflected by the recording surface, a light receiving element that receives light collected by the objective lens, and the like. In order to accurately read data from the recording surface, the position of the optical pickup is usually controlled by a tracking servo and a focus servo. The tracking servo controls the radial position of the optical pickup based on the tracking error signal, and the focus servo controls the distance between the optical pickup and the optical disk based on the focus error signal.

  The astigmatism method is generally used for the focus servo. In the astigmatism method, light reflected by a reflecting surface of an optical disk is received by a light receiving element divided into four parts, and focus is controlled based on a difference in output voltage of the diagonal light receiving element. The difference between the output voltages is a focus error signal FE having an S-shaped characteristic as shown in FIG. 9, and a peak value is generated on the positive side when the distance between the objective lens and the reflecting surface of the optical disk is short, and on the negative side when the distance is long. A peak value occurs and is zero if the focus is in agreement. Between the positive and negative peaks of the focus error signal FE, FS is a period during which the focus servo is turned on, that is, a period during which the focal position of the optical pickup can be followed. When the focus servo period FS is lost due to a disturbance or the like, the focus pull-in process is executed.

  When the focus pull-in process is executed, if the optical pickup is brought close to the optical disk at a stroke, the optical pickup may hit the recording surface of the optical disk and damage the recording surface. Therefore, control is performed so that the moving distance of the optical pickup gradually increases. An example is shown in FIG. As shown in the figure, the focus search signal for moving the optical pickup is a triangular wave or sawtooth wave, and the optical pickup is moved according to the amplitude, and the focusable position, that is, the position where focus servo is possible, is sought. The

  In addition, since the optical disk has warpage, surface vibration occurs when the optical disk is rotated. When the optical disc is rotated at high speed, the focus pull-in process is likely to succeed if the surface shake amount is small, but if the surface shake amount increases, the relative speed of the optical disc surface and the objective lens increases, and the focus pull-in process may fail. There is sex. In Patent Document 1, when the focus pull-in process fails, the movement of the optical pickup is controlled using the rotation speed of the optical disk, the movement speed and the movement amount of the objective lens stored in the memory during the recovery process, and the surface wobbling of the optical disk is controlled. It enables early focus pull-in processing regardless of the amount.

  When controlling the rotational speed of the optical disk, if an abrupt torque is applied to the optical disk, the optical disk may be deformed and the surface shake amount may increase, exceeding the surface shake amount allowed by the focus servo. Patent Document 2 discloses an optical disc apparatus that detects a disc runout amount and performs a seek operation using a control signal that increases a gain with respect to the runout amount in order to solve such a problem. Patent Document 3 discloses an optical disk device that determines that an optical disk with surface vibration is being reproduced when the jitter amount of a reproduction signal synchronized with the period of surface vibration exceeds a threshold, and increases the gain of the servo system of the optical pickup. Disclosure. Patent Document 4 includes an information storage unit that stores information read from an optical disk, monitors the information stored in the information storage unit, and performs focus offset adjustment only when the information is greater than or equal to a certain time. Thus, an optical disk reproducing apparatus that prevents interruption of audio and video is disclosed.

JP 2004-185741 A JP 2000-20989 A JP 2004-280990 A JP 2000-163778 A

  As described above, the conventional optical disk reproducing apparatus executes the focus pull-in process when the focus is lost due to disturbances such as vibration and surface shake, and if the focus pull-in process is successful, the control shifts to the focus servo. If the pull-in process fails, the recovery process is executed and the focus pull-in process is repeated. In addition, as shown in Patent Document 4, data read out from an optical disk at high speed is stored in a buffer memory and the data read out from the buffer memory is reproduced. This prevents the occurrence of playback interruption.

  However, the focus pull-in process of the conventional optical disk playback device has the following problems. The success rate of the focus pull-in process varies depending on the disk rotation speed, surface deflection, focus servo gain, etc., but conventional optical disk playback devices perform re-draw process under certain conditions (rotation speed / gain, etc.). Therefore, in some cases, the number of focus pull-in processing failures increases, that is, the number of retries (recovery processing) increases. If the time for the focus redrawing process exceeds the reproducible time based on the data stored in the buffer memory, sound interruption and video skipping occur during that time.

  On the other hand, if the focus search speed and the disk rotation speed are reduced during the focus pull-in process and the focus servo gain is increased, the probability of success in one focus pull-in process increases, but the focus search gain increases. Increasing the disk speed and changing the rotational speed of the disk by accelerating or decelerating the spindle motor increases the power consumption, and is not always a preferable method.

  The present invention solves the conventional problems as described above, and an optical disc capable of reducing power consumption while minimizing the occurrence of sound interruption and image skip when out of focus occurs. It is an object of the present invention to provide a playback apparatus and a focus pull-in control method.

  An optical disk reproducing apparatus according to the present invention comprises a rotating means for rotating a disk, a reading means for optically reading data recorded on the disk, and a buffer means for temporarily storing data read by the reading means. A reproducing means for reproducing the data output from the buffer means, a detecting means for detecting the amount of data stored in the buffer means, and a servo control means for servo-controlling the position of the reading means, The servo control means determines the operation mode of the focus pull-in process based on the data amount detected by the detection means when the focus servo is released.

  Preferably, the servo control means selects one operation mode from a plurality of operation modes prepared in advance, and executes a focus pull-in process based on the selected operation mode. Preferably, the servo control means determines whether the remaining amount of data in the buffer means corresponds to a plurality of stages based on a detection result of the detection means, and the servo control means operates according to the determined stage. The focus pull-in process is executed according to the mode. Preferably, the operation mode is set by at least one of a disc rotation speed, a focus search amplitude, a focus search speed or time, and a focus pull-in gain. Preferably, the optical disk reproducing apparatus further includes a surface shake amount detecting means for detecting a surface shake amount at the time of disk reproduction, and the servo control means performs a focus redrawing process based on the surface shake amount and the data amount of the buffer means. Set the disc rotation speed. Preferably, the servo control means determines whether or not the data amount of the buffer means is larger than a first threshold value. When the data amount is larger than the first threshold value, the servo control means has a first focus pull-in gain. When the first operation mode is selected and the data amount is smaller than the first threshold value, the second operation mode having the second focus pull-in gain is selected, and the first focus pull-in gain is set to the second focus pull-in gain. Smaller than the focus pull-in gain. Preferably, the servo control means determines whether or not the data amount of the buffer means is larger than a first threshold value, and when the data amount is larger than the first threshold value, the servo control means has a first focus search amplitude. When the first operation mode is selected and the data amount is smaller than the first threshold value, the second operation mode having the second focus search amplitude is selected, and the first focus search amplitude is the second Is smaller than the focus search amplitude. Preferably, the servo control means determines whether or not the data amount of the buffer means is larger than a first threshold value. When the data amount is larger than the first threshold value, the servo control means has a first focus search speed. When the first operation mode is selected and the amount of data is smaller than the first threshold value, the second operation mode having the second focus search speed is selected, and the first focus search speed is the second Faster than the focus search speed. Preferably, the servo control means determines whether or not the data amount of the buffer means is larger than a first threshold value, and when the data amount is larger than the first threshold value, the rotation means has a first rotational speed. And when the amount of data is smaller than the first threshold, the second operation mode having the second rotational speed is selected, and the first rotational speed is It is faster than the rotational speed of 2. Preferably, the optical disk reproducing apparatus further includes a surface shake amount detecting means for detecting a surface shake amount at the time of reproducing the disk, and the servo control means determines that the first rotational speed is greater than the first rotational speed when the surface shake amount is a certain value or more. Is set to a low third rotation speed. Preferably, the rotation speed of the rotation means is smaller as the data amount of the buffer means is smaller, the focus search speed is smaller as the data amount of the buffer is smaller, and the focus search amplitude is larger as the data amount of the buffer is smaller, The operation mode is set so that the focus pull-in gain increases as the data amount of the buffer decreases. Preferably, the operation mode is set so that the rotation speed of the rotation means becomes lower as the surface runout amount increases. Preferably, the servo control means further includes a determination means for determining whether or not the focus servo pull-in process is successful. When the determination means determines that the focus servo pull-in process is not successful, the processing content corresponding to the data amount of the buffer means is Perform the set recovery process. Preferably, the recovery process includes a process for increasing the focus pull-in gain when the data amount of the buffer means is a predetermined value or less. Preferably, the recovery processing further includes processing contents for reducing the rotation speed of the rotating means from high speed to low speed. Preferably, in the recovery process, when the data amount of the buffer means exceeds a certain value, the rotation speed of the rotation means is decreased stepwise according to the number of retries. Preferably, the recovery process further increases the focus pull-in gain stepwise according to the number of retries.

  The focus pull-in control method according to the present invention reads data from a disk at a speed higher than the normal playback speed, stores the read data in a buffer, and reads the data from the buffer at the normal playback speed for playback. When it is detected that the focus servo is released, the amount of data stored in the buffer is determined, and the operation mode of the focus pull-in process is set based on the determined amount of data. The operation mode is determined by at least one of a disc rotation speed, a focus search amplitude, a focus search speed or time, and a focus pull-in gain.

  According to the present invention, since the operation mode of the focus pull-in process is determined according to the amount of data stored in the buffer, it is possible to suppress power consumption while suppressing occurrence of sound interruption and video skipping. .

It is a block diagram which shows schematic structure of the optical disk reproducing | regenerating apparatus based on the Example of this invention. It is a flowchart explaining the operation | movement of the focus drawing-in process of the optical disk reproducing device based on the Example of this invention. It is a figure explaining an example of the operation mode according to the data remaining amount of the buffer by 1st Example of this invention. It is a figure explaining the relationship between a focus pull-in gain and power consumption. It is a graph which shows an example of a focus open loop characteristic. It is a figure explaining the relationship between the amount of surface shake by the 2nd Example of this invention, and the rotational speed of an optical disk. It is a figure which shows the power consumption example of the operation mode of the focus pull-in process in the 1st and 2nd Example of this invention. It is a figure explaining the operation mode of the focus drawing-in process by the 3rd Example of this invention. It is a figure explaining the detail of the recovery process shown in FIG. It is a figure which shows the S character characteristic of the focus error signal of an optical disk reproducing device. It is a figure which shows an example of the focus search signal of the conventional optical disk reproducing | regenerating apparatus.

  The optical disc playback apparatus according to the present invention is preferably implemented in an audio system or navigation system mounted on a vehicle or the like. The recording medium played back by the optical disc playback apparatus is an optical disc such as a CD-ROM, CD-R, CD-RW, DVD, or Blu-ray disc. Such an optical disc is required for audio data, video data, and the like. Memorize various data. The recorded data may be compressed into a predetermined format. Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram showing a schematic configuration of an optical disk reproducing apparatus according to an embodiment of the present invention. An optical disk reproducing apparatus 1 includes a spindle motor 12 that rotates an optical disk 10 mounted on a turntable or the like, an objective lens 14, a light emitting element and a light receiving element (not shown), irradiates light onto the recording surface of the optical disk, and emits light from the recording surface. An optical pickup 16 that converts the reflected light into an electric signal, a data reading unit 18 that receives the electric signal from the optical pickup 16, a buffer 20, and a reproducing unit 22 are included.

  The data reading unit 18 includes an amplifier that generates an RF signal for reproduction, an analog / digital converter that converts the generated RF signal into a digital signal, and a focus error signal and a tracking error signal necessary for servo control and the like. Is generated.

  The buffer 20 sequentially accumulates the read data output from the data reading unit 18. The buffer 20 is composed of, for example, a FIFO memory capable of reading and writing data on a first-in first-out basis. Although the data reading speed of the data reading unit 18 depends on the rotation speed of the optical disc 10, when the reading speed of the data reading unit 18 is faster than the normal playback speed of the playback unit 22, that is, from the data reading unit 18 to the buffer 20. When the amount of data supplied per unit time is larger than the amount of data per unit time provided from the buffer 20 to the reproduction unit 22, read data is stored in the buffer 20. If the buffer 20 having a large storage capacity is used, it is possible to accumulate as much read data as possible, and even if reading by the optical pickup 16 is temporarily interrupted, the read data accumulated in the buffer 20 can be reproduced. , The occurrence of sound interruption and video skipping is suppressed.

  The playback unit 22 receives the read data output from the buffer 20, separates the audio data and video data, and further decodes the separated audio data and video data. The reproduced data is provided to an audio output unit and a display unit (not shown).

  The optical disc reproducing apparatus 1 further receives a focus error signal and a tracking error signal from the detection unit 24 for detecting the amount of data stored in the buffer 20 and the data reading unit 18 and performs tracking servo and focus servo for the optical pickup 16. A circuit 26, a drive circuit 28 that generates a tracking drive signal and a focus drive signal based on a signal from the servo circuit 26, an actuator 30 that drives the optical pickup 16 based on a tracking drive signal and a focus drive signal from the drive circuit 28, and a detector The detection result from 24, the tracking error signal, the focus error signal, etc. are received, and the rotation speed of the spindle motor 12 is controlled based on the control from the controller 32 and the controller 32 for controlling the servo circuit 26 and others. Motor drive unit 34 to a constant, and a memory 36 for storing information and programs which the controller 32 requires.

  The detection unit 24 monitors the remaining data amount or free space stored in the buffer 20 and provides the result to the controller 32. Preferably, the detection unit 24 always detects the remaining amount of data and provides this to the controller 32. The controller 32 controls the rotation speed of the optical disk 10 based on the data remaining amount in the buffer 20 so that the remaining data amount in the buffer 20 does not overflow or is kept constant during reproduction. can do. If the focus pull-in process, which will be described later, is being performed, the controller 32 causes the focus pull-in process and / or the recovery process to operate according to the remaining data amount in the buffer 20.

  The servo circuit 26 controls the drive circuit 28 so that the error becomes zero based on the tracking error signal and the focus error signal when the servo control is on, and the drive circuit 28 accordingly tracks the tracking drive signal and the focus drive signal. Is generated and output to the actuator 30. On the other hand, when the servo control is lost, the servo circuit 26 executes a servo pull-in process that enables the servo control. In one embodiment, the controller 32 determines whether or not the servo control has been released based on the tracking error signal and / or the focus error signal. If it is determined that the servo control has been released, the controller 32 controls the servo circuit 30. Performs the servo pull-in process. In another embodiment, it may be determined whether the servo is released by the servo circuit 32 itself, and the servo pull-in process may be executed. In a further preferred aspect, the controller 32 can detect the surface shake amount of the optical disc based on the voltage of the focus error signal or the voltage of the RF signal generated by the data reading unit 18. The controller 32 can determine the operation mode of the servo pull-in process according to the surface runout amount.

  The optical disk reproducing apparatus 1 according to the present embodiment performs a focus pull-in process for reducing power consumption while minimizing the occurrence of sound interruption and video skipping according to the remaining data in the buffer 20 when the focus servo is released. I do. Hereinafter, the operation of the focus pull-in process according to the embodiment of the present invention will be described.

  FIG. 2 is a flowchart for explaining the focus pull-in process when the focus is lost during data reproduction. The optical disk 10 is rotated at a predetermined rotation speed, and an electric signal obtained through the optical pickup 16 is supplied to the data reading unit 18 to read data (S100). The read data is stored in the buffer 20 (S102) and output to the reproduction unit 22, and the data reproduced by the reproduction unit 22 is output as audio and / or images (S104).

  The controller 32 monitors the focus error signal and determines whether or not the focus has been lost (S106). As shown in FIG. 8, the focus servo can be performed (ON state) when the focus error signal is within the range FS. However, when the focus servo is out of the range FS, it is determined that the focus servo is out. If no out-of-focus has occurred, focus servo is performed by the servo circuit 26, and steps S100 to S104 are repeated.

  If the controller 32 determines that the focus has been lost, the controller 32 proceeds to a focus pull-in process. First, the controller 32 determines the remaining amount of data stored in the buffer 20 based on the detection result from the detection unit 24 (S108). In one preferred example, the remaining data level is compared to one or more thresholds to determine the level of remaining data. For example, when compared with one threshold value, two levels are determined whether or not the remaining data amount is larger than the threshold value. By comparing with N thresholds (N is an integer equal to or greater than 1), it is determined which level of the N + 1 level the remaining data amount is. The determination of the remaining amount of data may be to determine the absolute amount of data accumulated in the buffer 20 or to determine the proportion of the entire buffer 20 in the storage capacity.

  The controller 32 determines the operation mode of the focus pull-in process according to the data remaining amount in the buffer 20. As described above, when the remaining data amount is determined at the level of N + 1, there are N + 1 operation modes in the focus pull-in process. In one preferred example, N + 1 operation modes are prepared in advance, and an optimum operation mode can be selected from them. In the flowchart of FIG. 2, for ease of explanation, an example is shown in which the remaining data level is determined at two levels, large and small.

  When the controller 32 determines that the remaining amount of data is equal to or greater than a certain level, the controller 32 selects an operation mode in which power consumption during the focus pull-in process is suppressed (S112). Although details of this operation mode will be described later, when a certain amount of remaining data is accumulated in the buffer 20, the time required for the focus pull-in process is small, and the success rate of the focus pull-in process is not necessarily high. Also good. That is, a retry is possible even if the focus pull-in process is not successful. Therefore, if the remaining amount of data is greater than or equal to a certain level, an operation mode that suppresses power consumption as much as possible is given priority over a success rate.

  On the other hand, when it is determined that the remaining amount of data is less than a certain level, the controller 32 selects an operation mode in which the success rate of the focus pull-in process is high (S114). Although details of this operation mode will be described later, when the remaining amount of data less than a certain amount is accumulated in the buffer 20, the focus pull-in process is completed in a short time to suppress the occurrence of sound interruption and video skipping. Is desired. Therefore, priority is given to an operation mode in which the success rate is higher than suppression of power consumption.

  The controller 32 controls the servo circuit 26 and the motor drive unit 34 according to the selected operation mode, the optical pickup is moved based on the focus search signal from the actuator 30, and the focus pull-in process is executed (S116). Here, the focus pull-in process is a process in which the optical pickup 16 is moved by the actuator 30, the focus servo is turned on by a focus error signal detected when the optical pickup 10 passes through the focus position, and the focus is focused. is there.

  When the focus pull-in process is successful (S118), the focus servo by the servo circuit 26 is resumed. When the focus pull-in process fails, a recovery process is performed (S120). In one preferred example, in the recovery process, the level of the remaining amount of data in the buffer 20 is determined again, an operation mode corresponding to the level is selected, and the recovery process is executed according to the operation mode. This will be described later. In another example, the recovery process is executed in accordance with the same operation mode as the operation mode selected last time. The recovery process is repeated until focus is found.

  Next, the operation mode of the focus pull-in process will be described with reference to FIG. The example shown in FIG. 3 is an example when the number of thresholds N = 3, and the remaining data amount D of the buffer 20 has four levels, that is, 100% ≧ D> 75%, 75% ≧ D> 50. %, 50% ≧ D> 25%, 25% ≧ D ≧ 0%. Depending on the level of the remaining data D, an operation mode is set such that the success rate of the pull-in process is 70%, 80%, 90%, 100%. In this embodiment, the operation mode is set from four factors, that is, a disc rotation speed, a focus search speed (or focus search time) Fs, a focus search amplitude Fa, and a focus pull-in gain.

  When the remaining data D is greater than 75%, the success rate is set to 70%. Although the rotational speed of the disk is set to a high speed, the power consumption is suppressed as compared with the case where the rotational speed is set to a low speed because deceleration to a low speed is not required. In addition, the focus search speed Fs of the focus search signal is fast, and the focus search amplitude Fa is set to the minimum. The focus search signal is a signal that causes the actuator 30 to move the optical pickup 16. If the focus search speed (or time) Fs is fast and the amplitude Fa is minimum, the movement time and the movement amount of the optical pickup 16 are also limited. Therefore, power consumption by the actuator 30 is suppressed.

  Further, the focus pull-in gain is set to the minimum. FIG. 4 shows the relationship between the focus pull-in gain and power consumption. The servo circuit 26 includes a gain setting unit 26A for setting a focus gain therein. Here, with respect to the focus error signal to which the gain setting unit 26A is input, a waveform when gain = equal magnification and gain = 2 times is schematically represented. If the gain is the same magnification, the gain setting unit 26A outputs the input focus error signal to the drive circuit 28 with the same magnification, and the drive circuit 28 outputs the same magnification drive output to the actuator 30. If the gain is twice, the gain setting unit 26A outputs a signal having an amplitude twice that of the input focus error signal to the drive circuit 28. The drive circuit 28 outputs the drive signal with the gain increased to the actuator. Output to 30. Therefore, if the gain at the time of the focus pull-in process is increased, the drive amount by the actuator 30 is increased, and the power consumption is accordingly increased.

  When the remaining data amount D is 75% or less and when the remaining data amount D is 50% or less, the rotation speed of the optical disk is somewhat reduced, the focus search speed Fs is maintained as it is, and the focus search amplitude Fa is set to the middle. The focus pull-in gain is set to the middle. As a result, the success rate can be 80% and 90%.

  When the remaining amount of data is 25% or less, the rotation speed of the optical disc is set to a low speed, the focus search speed Fs is slow, the focus search amplitude Fa is set to the maximum, and the focus pull-in gain is set to increase. Therefore, the success rate can be 100%. By decelerating the rotational speed, the drive current for accelerating / stopping the spindle motor 12 increases, and the power consumption increases. Further, the increase in the focus search amplitude Fa and the focus pull-in gain increases the power consumption because the driving amount by the actuator 30 increases. Instead, the focus can be easily pulled in by reducing the focus search speed Fs.

  FIG. 5 shows the focus open characteristic. This represents a gain necessary to follow the deviation (acceleration). As shown in the figure, by setting the focus servo system to +6 dB, it is possible to suppress the acceleration twice as much as normal. In the case of the same acceleration, the residual of the target value can be halved. That is, increasing the focus pull-in gain increases the suppression, and the focus is easily pulled in.

  It should be noted that “fast”, “slow”, “minimum”, “intermediate”, “maximum”, etc. used in disc rotation speed, focus search speed, focus search amplitude, and focus pull-in gain mean the remaining data amount. Note that it is used to represent the relative relationship between each level corresponding to D.

  As described above, according to this embodiment, since the operation mode of the focus pull-in process is determined or selected according to the remaining data amount of the buffer, the power consumption can be reduced while minimizing the occurrence of sound interruption and video skipping. Can be reduced.

  Next, a second embodiment of the present invention will be described. In the second embodiment, the rotational speed of the disk is set in consideration of the amount of surface deflection of the disk. As described above, the controller 32 can detect the surface shake amount during rotation of the optical disk based on the potential of the focus error signal and the RF signal. When the optical disk is rotated at high speed, the probability of successful focus pull-in processing increases if the surface shake amount is small. However, when the surface shake amount increases, the relative speed between the recording surface of the optical disk and the objective lens increases, so that the focus pull-in process increases. The probability of processing failure increases.

  FIG. 6 shows the relationship between the remaining amount of data in the buffer and the change in the number of revolutions of the optical disk when the surface runout amount is taken into consideration. In the first embodiment, when the remaining data D is 50% or more, the optical disk is rotated at a high speed. However, as described above, when the surface runout amount increases, the target success rate is 70% and 80%. May decrease. Therefore, in the second embodiment, when it is determined that the surface shake amount is equal to or greater than a certain value, the controller 32 determines that the rotation speed of the optical disk is medium even if the remaining data amount D is 50% or more. The motor drive unit 34 is controlled so that In the above example, it is determined whether or not the surface shake amount is a certain level or more. However, the magnitude of the surface shake amount is determined at a plurality of more detailed levels, and the number of rotations corresponding to the plurality of detailed levels is determined. It may be determined.

  As described above, according to the second embodiment, since the rotational speed is set in consideration of the amount of surface shake, the decrease in the success rate of the focus pull-in process especially when the data remaining amount D is large is suppressed. be able to.

  FIG. 6A shows a comparative example of power consumption when focus pull-in processing is performed in each operation mode. The remaining data D is classified into level 1, level 2 and level 3 as shown in FIG. The operation modes corresponding to levels 1, 2, and 3 have the contents shown in FIG. 3 except for the rotational speed of the disk. The rotational speed takes into account the surface shake amount shown in FIG. For example, at level 1 where the remaining amount of data is 75% or more, the focus search time Fs = 0.1, the focus search amplitude Fa = 0.014, and the required power when the focus pull-in gain is minimum = 0.057. The power per focus pull-in process including power consumption by the spindle motor is about 0.22 mW. The power consumption when the number of retries (recovery processing) is based on 3 is about 0.7 mW. On the other hand, since the operation corresponding to level 3 has a small amount of remaining data, the success rate is prioritized over the suppression of power consumption, so the power consumption per focus pull-in process is about 3.11. It is about 14 times the power consumption at level 1.

  Next, a third embodiment of the present invention will be described. The third embodiment relates to recovery processing during focus pull-in processing. As described in steps S118 and S120 in the flow of FIG. 2, the recovery process is a process that is continuously performed when the focus pull-in process is not successful.

  FIG. 7 shows the relationship between the playback condition and the recovery process. Here, the recovery process is shown when the remaining amount of data in the buffer is at two levels. When the remaining amount of data is small, the recovery process is selected according to the number of rotations of the disk and the amount of surface shake.

  As shown in the figure, when the remaining amount of data is small, the rotation speed is low, and the surface shake amount is small, a normal recovery operation is performed. However, when the surface runout amount is large, recovery 1 is selected. When the remaining amount of data is small and the rotation speed is high, recovery 2 or recovery 3 is selected according to the amount of surface shake. When the remaining amount of data is large, the recovery 4 is selected regardless of the rotational speed or the surface shake amount.

  FIG. 8 shows the processing contents of recovery 1 to 4. In the recovery 1 to 3 when the remaining amount of data is small, basically, the contents of the process for which the focus pull-in process succeeds without fail is set without giving priority to the reduction of power consumption. Minimizes the time required for recovery, enables unnecessary focus retry operations to be reduced, and suppresses the occurrence of sound interruptions and video skipping. Specifically, in recovery 1, since the amount of surface shake is large, the focus pull-in is facilitated by increasing the pull-in gain. In recovery 2, the number of rotations is reduced from a high speed to a low speed, thereby facilitating the retraction. In recovery 3, since the surface runout amount is large, the rotational speed is reduced from high speed to low speed, and the pull-in gain is increased.

  In the recovery 4 in which the remaining amount of data is large, processing details for switching the processing in stages according to the remaining amount of data are set. In the recovery 4, since the number of focus retries has a relatively large margin, for example, the rotational speed of the optical disk is gradually switched to a low speed in accordance with the number of retries, and the rotational speed is decelerated rapidly at one time. Also suppresses the power consumption of the spindle motor. In addition, the power gain is suppressed by increasing the pull-in gain stepwise in accordance with the number of retries.

  As described above, according to this embodiment, it is possible to select an optimum recovery process that minimizes power consumption while suppressing sound interruption and video skipping. Furthermore, by combining the third embodiment with the first and second embodiments, it is possible to optimize the operation mode of the focus pull-in process, the success rate of the recovery process, and the power consumption.

  In the above embodiment, the controller 32 selects an operation mode or processing content as defined in FIGS. 3, 6, 7, and 8 according to the remaining amount of data. Information for determining the processing content can be stored in the memory 36, for example. When the controller 32 determines that the focus has been lost, the controller 32 can execute the focus pull-in process according to the operation mode or the processing content stored in the memory 36.

  The preferred embodiment of the present invention has been described in detail above, but the present invention is not limited to the specific embodiment, and various modifications can be made within the scope of the present invention described in the claims. Deformation / change is possible.

1: optical disk device 10: optical disk 12: spindle motor 14: objective lens 16: optical pickup 18: data reading unit 20: buffer 22: reproducing unit 24: detection unit 26: servo circuit 26A: gain setting circuit 28: drive circuit 30: Actuator 32: Controller 34: Motor drive unit 36: Memory

Claims (20)

Rotating means for rotating the disc;
Reading means for optically reading data recorded on the disc;
Buffer means for temporarily storing data read by the reading means;
Reproducing means for reproducing data output from the buffer means;
Detecting means for detecting the amount of data stored in the buffer means;
Servo control means for servo-controlling the position of the reading means,
The servo control means determines the operation mode of the focus pull-in process based on the amount of data detected by the detection means when the focus servo is released ,
The operation mode is set by at least one of a disc rotation speed, a focus search amplitude, a focus search speed or time, and a focus pull-in gain . The optical disk reproducing apparatus according to claim 1, wherein the servo control unit selects one operation mode from a plurality of operation modes prepared in advance, and executes a focus pull-in process based on the selected operation mode. The servo control means determines whether the remaining data amount of the buffer means corresponds to a plurality of stages based on the detection result of the detection means, and the servo control means follows an operation mode according to the determined stage. The optical disk reproducing apparatus according to claim 1, wherein focus pull-in processing is executed. The optical disk reproducing apparatus further includes a surface shake amount detecting unit that detects a surface shake amount during disk reproduction, and the servo control unit performs a focus retraction process based on the surface shake amount and the data amount of the buffer unit. setting the disk rotational speed, the optical disk reproducing apparatus according to 3 any one claims 1. The servo control means determines whether or not the amount of data in the buffer means is larger than a first threshold value. When the data amount is larger than the first threshold value, the first servo control means has a first focus pull-in gain. When the operation mode is selected and the data amount is smaller than the first threshold value, the second operation mode having the second focus pull-in gain is selected, and the first focus pull-in gain is set to the second focus pull-in gain. less than retraction gain, the optical disk reproducing apparatus according to 4 any one claims 1. The servo control means determines whether or not the data amount of the buffer means is larger than a first threshold value. When the data amount is larger than the first threshold value, the first servo control means has a first focus search amplitude. When an operation mode is selected and the amount of data is less than the first threshold, a second operation mode having a second focus search amplitude is selected, and the first focus search amplitude is the second focus smaller than the search amplitude, the optical disk reproducing apparatus according to 5 any one claims 1. The servo control means determines whether or not the data amount of the buffer means is larger than a first threshold value. When the data amount is larger than the first threshold value, the first servo search means has a first focus search speed. When the operation mode is selected and the data amount is smaller than the first threshold, the second operation mode having the second focus search speed is selected, and the first focus search speed is the second focus search speed. faster than search speed, the optical disk reproducing apparatus according to 6 any one claims 1. The servo control means determines whether or not the data amount of the buffer means is larger than a first threshold value. When the data amount is larger than the first threshold value, the rotating means has a first rotation speed. When the first operation mode is selected and the amount of data is smaller than the first threshold value, the second operation mode having the second rotation speed is selected, and the first rotation speed is the second rotation speed is faster than the rotational speed, the optical disk reproducing apparatus according to any one claims 1 to 7. The optical disk reproducing apparatus further includes a surface shake amount detecting means for detecting a surface shake amount during disk reproduction, and the servo control means is lower than the first rotational speed when the surface shake amount is a certain value or more. The optical disk reproducing apparatus according to claim 8 , wherein the optical disk reproducing apparatus is set to a third rotation speed. The rotation speed of the rotation means is smaller as the data amount of the buffer means is smaller, the focus search speed is smaller as the data amount of the buffer means is smaller, and the focus search amplitude is larger as the data amount of the buffer means is smaller. 2. The optical disc apparatus according to claim 1 , wherein an operation mode is set so that the focus pull-in gain increases as the data amount of the buffer means decreases. The rotational speed of the rotating means the operating mode is set to be slower larger the surface deflection amount, the optical disk reproducing apparatus according to 10 any one claims 1. The servo control means further includes a determination means for determining whether or not the focus servo pull-in process is successful. When the determination means determines that the focus servo pull-in process is not successful, a processing content corresponding to the data amount of the buffer means is set. executing the recovery processing was optical disk reproducing apparatus according to 11 any one claims 1. 13. The optical disk reproducing apparatus according to claim 12 , wherein the recovery process includes a process content for increasing a focus pull-in gain when a data amount of the buffer unit is a predetermined value or less. The optical disk reproducing apparatus according to claim 13 , wherein the recovery process further includes a process content for reducing the rotation speed of the rotation unit from a high speed to a low speed. The optical disk reproduction according to any one of claims 12 to 14 , wherein, in the recovery process, when the data amount of the buffer means exceeds a certain value, the rotation speed of the rotation means is decreased stepwise according to the number of retries. apparatus. The optical disk reproducing apparatus according to claim 15 , wherein the recovery process further increases the focus pull-in gain stepwise according to the number of retries. A focus pull-in control method for an optical disc playback apparatus that reads data from a disc at a speed faster than a normal playback speed, stores the read data in a buffer, reads the data from the buffer at the normal playback speed, and plays back the data.
When it is detected that the focus servo is released, the amount of data stored in the buffer is determined,
Based on the determined data amount, an operation mode of the focus pull-in process is determined,
The focus pull-in control method, wherein the operation mode is set by at least one of a disc rotation speed, a focus search amplitude, a focus search speed or time, and a focus pull gain. The focus pull-in control method according to claim 17 , wherein the focus pull-in control method further includes detecting a surface shake amount of the disk, and the rotation speed is set based on the surface shake amount. Rotational speed of the disk is smaller the smaller the data amount of the buffer, the focus search speed is smaller as the data amount of the buffer is small, the focus search amplitude is larger the smaller the data amount of the buffer, the focus pull gain operating mode so that the data amount becomes as small increase of the buffer is set, the focus pull-in control method according to claim 17 or 18. Focus pull-in control method further determines whether the focus servo pull-in process is successful, processing contents to perform recovery processing set in accordance with the data amount of the buffer when it is determined not successful, wherein Item 20. The focus pull-in control method according to any one of Items 17 to 19 .

Images