JP4666782B2 - Optical disk rotation control system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical disc recording / reproducing apparatus for recording and reproducing information on an optical disc such as a CD-R, CD-RW, CD-WO, MD, DVD, etc., and more particularly for accessing an optical disc at an arbitrary linear velocity. The present invention relates to an optical disk rotation control system.
[0002]
[Prior art]
In general, a data recording method for CDs and MDs employs a recording method based on CLV (constant linear velocity) control in order to increase the data storage capacity. Therefore, when reproducing data, it is necessary to change the rotational speed of the CD in accordance with the access position of the head with respect to the CD. FIG. 9 is a diagram for explaining an optical disk rotation control method in the conventional CLV method. Read data read from the optical disk 101 rotated by the spindle motor (SPM) 102 via the optical pickup 103 is supplied to the clock regenerator 104, where the clock signal CK is regenerated. The recovered clock signal CK is supplied to one comparison input terminal of the phase comparator 105. On the other hand, the reference clock CK 0 generated by the reference clock generator 106 is N-divided by the frequency divider 107 and supplied to the other comparison input terminal of the phase comparator 105. In the phase comparator 105, the phase of the recovered clock signal CK and the reference clock CKn divided by N is compared, and the phase difference output PC is fed back to the spindle motor 102 via the filter 108 and the SPM driver 109 to be fed to the spindle motor 102. Is controlled to rotate.
[0003]
According to this method, since the frequency of the reference clock CKn is constant, the frequency of the reproduction clock signal CK (reproduction data rate) is always equal to the reference clock signal CKn regardless of the access position to the optical disc 101. Spindle servo is applied. For this reason, the optical disc 101 is driven under CLV control so as to rotate at a high speed on the inner peripheral side and to rotate at a low speed on the outer peripheral side.
[0004]
[Problems to be solved by the invention]
By the way, the recording / reproducing speed of such an optical disc recording / reproducing apparatus is determined by the frequency of the reference clock signal DK 0 and the frequency dividing ratio of the frequency divider 107. In the case of a divide-by-2 clock, the recordable / reproducible speed that can be set is limited to 1 × speed, 2 × speed, 4 × speed, 8 × speed, 16 × speed,. There is also known an apparatus for switching a division ratio by combining a divide-by-2 low clock and a divide-by-3 high clock. Speed settings such as 12 times speed, etc. are added.
[0005]
However, in the optical disk rotation control method described above, the maximum speed is limited when the maximum recording / reproducing speed for the optical disk is limited due to the limit due to the maximum power of the laser, the limit due to the medium quality, the limit due to the system environment such as the transfer speed, etc. The fastest speed in the range cannot be selected. This is shown in FIG. Now, assuming that the maximum recording / reproducing linear velocity for an optical disc is 11.5 times speed, even if a divide-by-2 clock and a divide-by-3 clock are combined, only the 8 times speed can be selected as the maximum speed. For this reason, the area from the 8 × speed to the 11.5 × speed is an area that cannot be used even though recording / reproduction is possible.
[0006]
The present invention has been made in order to solve such problems, and provides an optical disk rotation control system that enables access at an arbitrary linear velocity, thereby maximizing system performance. The purpose is to provide.
[0007]
[Means for Solving the Problems]
A first optical disk rotation control method according to the present invention includes: a rotation driving unit that rotates and drives an optical disk to be accessed; a speed setting unit that sets a target linear velocity when accessing the optical disk; Read the time information of the currently accessed position, and set the rotation speed of the optical disk so that the linear speed of the optical disk becomes the linear speed set by the speed setting means at the access position of the time information next to the read time information The calculation means for calculating the rotation speed, the rotation speed detection means for detecting the actual rotation speed of the optical disc, and the actual rotation speed detected by the rotation speed detection means is the rotation speed calculated by the calculation means. And servo means for controlling the rotation drive means.
[0008]
The second optical disk rotation control method according to the present invention sets a rotation driving means for rotating and driving an optical disk on which data should be recorded at a constant linear velocity, and a target linear velocity for recording data on the optical disk. A speed setting means; and reading time information of a position currently recorded from the optical disc, and a linear velocity of the optical disc set by the speed setting means at a recording position of time information next to the read time information ; The calculation means for calculating the rotation speed of the optical disk as a set rotation speed, the rotation speed detection means for detecting the actual rotation speed of the optical disk, and the actual rotation speed detected by the rotation speed detection means is the calculation means. Servo means for driving and controlling the rotation driving means so as to achieve the rotation number calculated in (1).
[0009]
The third optical disk rotation control method according to the present invention sets a rotation driving means for rotating and driving an optical disk on which data is recorded at a constant linear speed, and a target linear speed when reproducing data from the optical disk. A speed setting means, and reads the time information of the current playback position from the optical disk, and the linear speed of the optical disk at the playback position of the time information next to the read time information is the linear speed set by the speed setting means; The calculation means for calculating the rotation speed of the optical disk as a set rotation speed, the rotation speed detection means for detecting the actual rotation speed of the optical disk, and the actual rotation speed detected by the rotation speed detection means is the calculation means. Servo means for driving and controlling the rotation driving means so as to achieve the rotation number calculated in (1).
[0010]
According to the present invention, the rotation speed of the optical disc at which the linear velocity of the optical disc becomes a preset linear velocity at the access position in the radial direction of the optical disc detected or predicted by the radial position detection means is set as the preset rotation speed. It is calculated by the calculation means, and the calculated set rotational speed and the actual rotational speed of the optical disc are compared, and the rotational drive means is driven and controlled so that the actual rotational speed matches the set rotational speed. Therefore, the target value of the linear velocity is not determined by the frequency of the basic clock signal and the frequency dividing ratio of the frequency divider as in the past, and any linear velocity can be set as the target value. become. As a result, the optical disc can be accessed at the highest recording / reproducing linear velocity at which the performance of the system is maximized.
[0011]
The rotational speed detection means can be, for example, a frequency generator that detects the rotational frequency of the rotational driving means and outputs a frequency pulse signal having a width corresponding to the rotational frequency. The pulse width of the frequency pulse corresponding to the set rotation speed is calculated, and the servo means measures the pulse width of the frequency pulse signal, for example, and compares this pulse width with the pulse width corresponding to the set rotation speed from the calculation means. Then, a comparator that outputs the deviation between the two, a filter that filters the output of the comparator, and a driver that drives the rotation driving means by the output of the filter can be configured.
[0012]
Further, the radial position detection means can be configured to detect the access position of the optical disk from time information read from the optical disk, for example. In this case, reading of the time information is intermittent, and therefore, from the start of the rotation control at the set rotation speed calculated from one time information to the start of the rotation control at the set rotation speed calculated from the next time information. , CAV (constant rotation speed) control is executed. For this reason, the curve of the linear velocity with respect to the radial direction position of the optical disc is stepwise when viewed microscopically, and the rotation control is pseudo CLV control, but here, such pseudo CLV control is also widely used. It is included in the category of CLV control.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of a main part of an optical disc recording / reproducing apparatus according to a preferred embodiment of the present invention.
The optical disc 1 is a recordable / reproducible disc such as CD-R, CD-RW, CD-WO, MD, DVD, etc., and data is recorded or recorded by the CLV method. The optical disc 1 is rotationally driven by a spindle motor (SPM) 2 serving as a rotational drive means, and data is recorded by the optical pickup 3 arranged oppositely, or the recorded data is read out. The RF signal data read from the optical pickup 3 is amplified by the read driver 4 and then supplied to an EFM / CIRC (Eight to Fourteen Modulation / Cross Interleaved Reed-Solomon Code) codec 5 for EFM demodulation and CIRC decoding. It is processed and output as digital data to an external device. The output of the read driver 4 is also supplied to the clock regenerator 6, where the read clock signal is regenerated and supplied as a reference clock for the EFM / CIRC codec. On the other hand, data to be recorded supplied from an external device is subjected to processing such as CIRC encoding processing, subcode data addition, EFM modulation, and the like by the EFM / CIRC codec 5 to become recording data, and then ALPC (Automatic Laser Power). Is supplied to the optical pickup 3 via the recording driver 8 as a recording signal whose laser power is adjusted. The optical pickup 3 forms recording pits on the optical disc 1 by the writing power of the laser. At the time of recording, the ALPC circuit 7 monitors the reflected light from the optical disk 1 via the reading driver 4 to control the laser power. The wobble formed on the optical disc 1 is detected by the wobble detector 9, and the clock generator 10 generates a recording clock from the wobble signal output from the wobble detector 9 and supplies it to the EFM / CIRC codec 5. . Further, the wobble signal from the wobble detector 9 is also supplied to the time code decoder 11, where an ATIP (Absolute Time In Pregroove) time code which is absolute time information included in the wobble signal is detected. The ATIP time code also indicates the access position in the radial direction of the optical disc 1 and is supplied to the controller 12.
[0014]
The controller (MPU) 12 controls the feed motor 14 via the feed servo circuit 13 and determines the position of the optical pickup 3 in the optical disk radial direction. Further, the controller 12 executes rotation control of the spindle motor 2 via the spindle servo circuit 15. The spindle motor 2 is provided with a frequency generator (FG) 16 for outputting an FG pulse having a pulse width corresponding to the rotation speed. The FG pulse from the frequency generator 16 is supplied to the spindle servo circuit 15. Has been. The target linear velocity when accessing the optical disc 1 is set in the controller 12 by the velocity setting unit 17. The controller 12 calculates the current access position in the radial direction of the optical disc 1 from the ATIP time code decoded by the time code decoder 11, and sets the linear velocity of the optical disc 1 at the calculated access position by the speed setting unit 17. The number of revolutions of the optical disk 1 that achieves the target linear velocity is calculated, and information indicating the pulse width of the FG pulse that should be obtained when the spindle motor 2 is rotated at this number of revolutions is set to the spindle servo circuit 15 as the set number of revolutions. Set.
[0015]
The spindle servo circuit 15 includes a comparator 21, a filter 22, and an SPG driver 23. The comparator 21 compares the set rotation speed (FG pulse width) from the controller 12 with the FG pulse from the frequency generator 17, and feeds back the error to the spindle motor 2 via the filter 22 and the SPM driver 23. Thus, the rotation of the spindle motor 2 is controlled.
[0016]
For example, as shown in FIG. 2, the comparator 21 counts the reference clock generator 31 that generates the reference clock signal CKr, the gate circuit 32 that gates the reference clock CKr with an FG pulse, and the output of the gate circuit 32. The counter 33, an RS-flip-flop circuit 34 that is set at the rising edge of the FG pulse, is reset at the rising edge of the reference clock signal CKr and resets the count value of the counter 33, and the count value of the counter 33 and the set rotation from the controller 12 And a subtractor 35 that outputs a difference from the number as an error. With such a configuration, the comparator 1 measures the number of pulses of the reference pulse signal CKr within the pulse width of the FG pulse from the frequency generator 17 with the counter 33 and sets it from the controller 12 as shown in FIG. Compared with the number of pulses corresponding to the set rotational speed, the error signal of both is output.
[0017]
Next, the rotation control operation of the optical disc during recording by the optical disc recording / reproducing apparatus configured as described above will be described. FIG. 4 is a diagram showing the relationship between the access (recording) position in the radial direction of the optical disc 1 in this embodiment, the rotational speed, and the linear velocity. The rotation control of the optical disk in this embodiment is Partial CAV control, and the CAV control in which the rotation speed of the spindle motor 2 is set to a controllable maximum rotation speed Nm on the inner peripheral side of the optical disk 1 where recording is started. Is done. The pseudo CLV control is performed at a position outside the access position rm where the linear velocity reaches the target velocity or the limit velocity Vm.
[0018]
FIG. 5 is a flowchart showing the processing of the controller 12. If recording is started from the innermost periphery of the program area of the optical disc 1, the controller 12 first corresponds to the rotation speed Nm so as to set the rotation speed of the spindle motor 2 to the rotation speed Nm at the start of rotation. The pulse count number is set in the comparator 21 (S1). A hall element incorporated as a detector in a frequency generator 16 provided in the spindle motor 2 generates an FG pulse signal having a width corresponding to the rotational frequency of the spindle motor 2. The comparator 21 measures the number of pulses of the reference pulse signal CKr that falls within the FG pulse width received from the frequency generator 16, compares it with the number of pulses set by the controller 12, and outputs the error. The error signal is supplied to the spindle motor 2 via the filter 22 and the SPM driver 23 and controls the rotation speed of the spindle motor 2. When the desired rotation speed Nm is reached, the CAV control loop of the spindle servo 15 is closed.
[0019]
When the CLV optical disk 1 is CAV-controlled, the linear velocity increases as it moves from the inner circumference side to the outer circumference side as shown in FIG. An increase in linear velocity corresponds to high-speed recording. The higher the recording speed, the more recording laser power is required. However, there is a limit to the output of the laser diode (LD). If the limit is exceeded, it will lead to LD breakdown. Therefore, the maximum recording speed has a peak. In addition, the maximum recording speed is limited by the system environment such as the disk quality and the data transfer speed.
[0020]
The optical pickup 3 reads the ATIP time code on the optical disc 1 while recording. This time code is decoded by the time code decoder 11. As this time code, a prepit, a fine clock mark, etc. can be used in addition to the wobble signal. As shown in FIG. 6, these time codes are defined in units of frames, and the ATIP time code is decoded by the time code decoder 11 when the frame is read. The ATIP time code corresponds to the radial position on the optical disk 1, and the optical disk rotation speed corresponding to the code position can be calculated from this time code.
[0021]
When recording is started by the CAV rotation control, the target speed set by the speed setting unit 17 is reached. In particular, the limit speed Vm is reached when the maximum speed is set as the target speed. In the following description, the case where the target speed is set to the limit speed Vm will be described, but it goes without saying that the same operation is performed even in the case of any other target speed. The time code at the radial position rm reaching the limit velocity Vm shown in FIG. 4B is calculated by the controller 12 from the limited maximum recording linear velocity, the basic linear velocity of the optical disc 1, and the track pitch (S2). When the controller 12 monitors the ATIP time code (S3) and detects that the optical pickup 3 has reached the limit position (S4), the controller 12 changes the number of pulses set for CAV control so far, and the limit speed Vm. Shifts to pseudo CLV control.
[0022]
In this pseudo CLV control, the controller 12 calculates the rotational speed when the critical speed CLV control at the radial position is performed from the read ATIP time code (S6), and the pulse count corresponding to the rotational speed. Is set in the comparator 21 (S7). When one frame has passed, the next ATIP time code is read (S5). Similarly, the controller 12 calculates the rotational speed when the critical speed CLV control is performed at the radial position of the optical disc 1 corresponding to the ATIP time code (S6), and the pulse count corresponding to the rotational speed is compared with the comparator. 21 is set (S7). Thereafter, every time the ATIP time code advances by one frame, the controller 12 sets the number of pulses corresponding to the number of rotations in the comparator 21 (S5 to S6), and controls the spindle motor 2 so as to be the number of rotations. Thereby, pseudo CLV control recording can be performed by continuously connecting very fine CAV recording operations.
[0023]
By performing the above control, as shown in FIG. 7, it becomes possible to access in a linear velocity region that could not be used conventionally, and the maximum capacity of the system can be exhibited.
[0024]
FIG. 8 is a diagram for explaining a rotation control method of an optical disc according to another embodiment of the present invention. In this embodiment as well, the configuration of the optical disc recording / reproducing apparatus itself is the same as that shown in FIG. 1, and thus the description of the configuration of the apparatus is omitted.
In the previous embodiment, the controller 12 sets the pulse count number corresponding to the radial position from the read ATIP time code. In this case, the access end time of one frame slightly exceeds the limit speed Vm. become. Therefore, in this embodiment, when the ATIP time code is read, the controller 12 compares the pulse count number corresponding to the rotation speed when the critical speed CLV control is performed at the radial position of the ATIP time code of the next frame. Set to the vessel 21.
[0025]
According to this embodiment, since the linear velocity reaches the limit velocity Vm at the end of access of one frame, the linear velocity does not exceed the limit velocity Vm.
[0026]
In addition, this invention is not limited to embodiment mentioned above. For example, in each of the above embodiments, the rotation control of the optical disk at the time of data recording on the optical disk has been described. However, the same rotation control can be performed at the time of data reproduction from the optical disk recorded with CLV.
[0027]
In each of the above embodiments, for the CAV control, the servo is applied to the spindle motor 2 by comparing the frequency of the set rotational speed from the controller 12 and the pulse width of the FG pulse from the frequency generator 16. The phase error may be obtained by phase comparison between the FG pulse that is the target value generated in step 1 and the actual FG pulse, and the spindle motor 2 may be servoed based on this phase error. Furthermore, if both the frequency and phase are compared to obtain an error signal, the control accuracy is further improved.
[0028]
In each of the above embodiments, the present invention is applied to the Partial CAV system in which CAV control is performed on the inner periphery side of the optical disc 1, but depending on the value of the spindle motor rotation capability and the target linear velocity, the first (innermost) The pseudo CLV control described above may be performed from the (circumferential side).
[0029]
Furthermore, in the above embodiment, the controller 12 detects the access position in the radial direction of the optical disk based on the absolute time information called the ATIP time code decoded from the wobble signal. If permitted, an external linear scaler that detects the position of the optical pickup in the feed direction may be used as the radial position detection means. Furthermore, the access position in the radial direction of the optical disk may be predicted by the controller 12 according to the recording or reproduction time, for example, without detecting the access position in the radial direction. In the above embodiment, the rotation speed is set for each frame. However, the rotation speed may be set for every two or more frames.
[0030]
【The invention's effect】
As described above, according to the present invention, the rotation speed of the optical disk at which the linear velocity of the optical disk becomes a preset linear velocity at the access position is calculated by the calculation means as the set rotation speed, and the calculated set rotation speed Is compared with the actual rotational speed of the optical disc, and the rotational drive means is controlled so that the actual rotational speed matches the set rotational speed. An arbitrary linear velocity can be set as the target value without being determined by the frequency of the basic clock signal and the frequency division ratio of the frequency divider. As a result, the optical disc can be accessed at the highest recording / reproducing linear velocity at which the system has the maximum performance.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an optical disc recording / reproducing apparatus according to a first embodiment of the present invention.
FIG. 2 is a block diagram showing a configuration example of a comparator in the same device.
FIG. 3 is a diagram for explaining an operation of the comparator.
FIG. 4 is a graph showing the relationship between the radial position of the optical disc, the number of rotations, and the linear velocity by rotation control by the same apparatus.
FIG. 5 is a flowchart showing processing related to rotation control during recording by a controller in the apparatus.
FIG. 6 is a diagram for explaining an ATIP time code of an optical disc.
FIG. 7 is a graph showing the relationship between the radial position of the optical disc and the linear velocity for explaining the effect of the present invention.
FIG. 8 is a graph showing the relationship between the radial position of an optical disc, the number of revolutions, and the linear velocity according to the optical disc rotation control method according to another embodiment of the present invention.
FIG. 9 is a block diagram showing a configuration of a conventional optical disk rotation control device.
FIG. 10 is a graph showing the relationship between the radial position of an optical disc and the linear velocity in a conventional optical disc recording / reproducing apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1,101 ... Optical disk, 2,102 ... Spindle motor real, 3,103 ... Optical pick-up, 4 ... Read-out driver, 5 ... EFM / CIRC encoder, 6,104 ... Clock regenerator, 7 ... ALPC circuit, 8 ... Recording driver , 9 ... Wobble detector, 10 ... Clock generator, 11 ... Time code decoder, 12 ... Controller, 13 ... Feed servo circuit, 14 ... Feed motor, 15 ... Spindle servo circuit, 16 ... Frequency generator, 17 ... Speed setting 21: Comparator, 22, 108: Filter, 23, 109: SPM driver, 106: Reference clock generator, 107: Frequency divider.

Claims (4)

Rotational drive means for rotationally driving an optical disk to record data at a constant linear velocity;
Speed setting means for setting a target linear speed when data is recorded on the optical disc;
Rotation of the optical disc in which time information of a position currently recorded from the optical disc is read and the linear velocity of the optical disc becomes a linear velocity set by the velocity setting means at a recording position of time information next to the read time information Calculating means for calculating the number as the set rotational speed;
A rotational speed detection means for detecting an actual rotational speed of the optical disc;
Servo means for driving and controlling the rotational drive means so that the actual rotational speed detected by the rotational speed detection means becomes the rotational speed calculated by the computing means. Rotation control method. Rotation driving means for rotating and driving an optical disk in which data is recorded at a constant linear velocity;
Speed setting means for setting a target linear speed when reproducing data from the optical disc;
Rotation of the optical disc is read from the optical disc at the current playback position, and the linear velocity of the optical disc becomes the linear velocity set by the speed setting means at the playback position of the time information next to the read time information. Calculating means for calculating the number as the set rotational speed;
A rotational speed detection means for detecting an actual rotational speed of the optical disc;
Servo means for driving and controlling the rotational drive means so that the actual rotational speed detected by the rotational speed detection means becomes the rotational speed calculated by the computing means. Rotation control method. The rotation speed detection means is a frequency generator that detects a rotation frequency of the rotation drive means and outputs a frequency pulse signal having a width corresponding to the rotation frequency,
The calculation means calculates a pulse width of a frequency pulse corresponding to the set rotational speed,
The servo means measures the pulse width of the frequency pulse signal, compares the pulse width with a pulse width corresponding to the set rotational speed from the computing means, and outputs a deviation between the comparator and the comparison 3. The optical disk rotation control system according to claim 1, further comprising: a filter for filtering the output of the optical device; and a driver for driving the rotation driving means by the output of the filter. The speed setting means can set the maximum access speed magnification determined by at least one of the limits due to the quality of the optical disc, the limit of laser diode output and the limit of the system environment such as the data transfer speed as a target linear speed. rotation control method according to any one of the described wherein an optical disk according to claim 1 to 3, characterized in that.

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