JP2005018873A - Optical disk unit, and seek control method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical disk unit capable of speedily and stably performing fine seeking without using a speed sensor. <P>SOLUTION: The optical disk device reading the data recorded in the track on an optical disk by making an optical pickup travel by a drive motor 6 is provided with: a traveling speed arithmetic circuit 42 for calculating the traveling speed of the optical pickup based on the tracking error signal generated by the optical pickup when the optical disk traverses the track of the optical disk; a learning table for learning an error speed between a target speed and a traveling speed of the optical pickup in accordance with the number of remaining tracks when the number of remaining tracks to the number of target traveling tracks of the optical pickup becomes less than the specified number of tracks and the optical pickup is decelerated; and an error correction circuit 48 for controlling the drive motor 6 by using the error speed learnt from the learning table. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical disc apparatus that performs a track seek operation on an optical disc.
[0002]
[Prior art]
The optical disk device records predetermined data on the mounted optical disk or reproduces predetermined data from the optical disk. At this time, the optical disk drive device applies spindle servo so that the optical disk rotates at a rotation speed at which the speed of a predetermined track is constant. Also, tracking servo, focus servo, and thread servo are applied so that the laser spot of the laser beam generated by the laser diode built in the optical pickup head follows a predetermined track on the optical disk and data can be recorded or reproduced. It is done.
[0003]
Prior to recording or reproduction on the optical disc, a seek operation for moving the optical pickup head to a target track on the disc is performed. In this seek operation, there is a fine seek mode in which the optical pickup is accelerated in the direction of the target track by a feed motor, once roughly rough seek is performed in the vicinity of the target track, and then the target track is precisely tracked.
[0004]
In the seek operation, the target speed for moving the optical pickup head is obtained, the movement speed of the optical pickup head is detected, and the drive motor is controlled so that the movement speed of the optical pickup head follows the target speed.
[0005]
The control of the feed motor in the seek operation drives the feed motor so that the moving speed of the optical head follows the target speed. Since the target speed is always calculated according to the number of remaining tracks, the number of seek tracks and seek A reaction error of the feed motor occurs depending on the direction. Further, a feed motor control error occurs due to individual differences of the optical disk apparatus.
[0006]
In order to reduce such an error, in the optical disc apparatus, it is possible to learn the speed difference between the target speed of the optical pickup head and the head speed, and to correct the target speed (Japanese Patent Laid-Open No. 6-203396). It is described in.
[0007]
In Patent Document 1, the head speed is detected by the head speed detection means, the learning result is stored in synchronization with the head position signal, the corrected target speed locus is generated, and the target speed is detected by the control signal generation means. An apparatus that drives a disk device head by calculating a control signal by calculating a speed error between the trajectory and the head speed or a speed error between the corrected target speed trajectory and the head speed is disclosed.
[0008]
Here, as a means for detecting the speed of the optical pickup head, there are a method of directly measuring the head speed using a sensor and a method of estimating the head speed from a change in a tracking error signal. Costs up.
[0009]
On the other hand, when the head speed is estimated from the change in the tracking error signal, a slow speed is detected in the precise seek mode, so that there is a problem that a speed detection delay usually occurs.
[0010]
That is, when the head speed is estimated from the time required for the optical pickup head to pass one track based on the change in the tracking error signal, it is possible to estimate the average speed at the time of passing one track. Since the speed is smaller than the average speed, the speed detection is delayed and the total seek time is lengthened.
[0011]
Furthermore, when detecting the direction of an optical pickup head using a tracking error signal, the optical head moves in a normal manner, but the head is reversed due to scratches or dirt on the disk surface or signal fluctuations. It may be judged that the car has run and the seek may be terminated. In this case, it is necessary to execute the seek again, which increases the total seek time.
[0012]
Therefore, in the apparatus disclosed in Patent Document 1, high-speed stabilization of the track seek operation is possible when the speed sensor is used, but sufficient high-speed stabilization cannot be realized when the speed sensor is not used. The problem arises.
[0013]
Furthermore, although the feed motor does not have uniform reaction errors in the seek direction, the apparatus disclosed in Patent Document 1 does not take into account errors caused by the seek direction.
[0014]
When the apparatus shown in Patent Document 1 does not use a speed sensor, a control delay of the feed motor may occur due to a detection delay of an error between the moving speed and the target speed, and reverse running may occur.
[0015]
The feed motor control during seek drives the feed motor so that the moving speed of the optical head follows the target speed, but it is determined that runaway occurs when the acceleration that occurs during deceleration operation in precise seek mode is simply compared with the previous value. And there is a risk that the seek will be terminated. Even in the case of such an erroneous determination, it is necessary to execute the seek again, which increases the total seek time.
[0016]
[Patent Document 1]
Japanese Patent Laid-Open No. 6-203396 (5th page, FIG. 7)
[0017]
[Problems to be solved by the invention]
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an optical disc apparatus capable of performing a precise seek operation at high speed and stably without using a speed sensor.
[0018]
[Means for Solving the Problems]
In order to solve the above-described problems, an optical disk apparatus according to the present invention is an optical disk apparatus that reads data recorded on a track on an optical disk by moving the optical pickup by a feed motor, and from the optical pickup when traversing the track of the optical disk. Speed calculating means for calculating the moving speed of the optical pickup based on the generated tracking error signal, and the optical pickup when the remaining number of tracks with respect to the target moving track number of the optical pickup is less than a predetermined number of tracks and the optical pickup is decelerated. Means for learning an error speed between the target speed and the moving speed corresponding to the number of remaining tracks, and means for controlling the feed motor using the error speed learned by the learning means.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0020]
FIG. 1 is a block diagram showing the configuration of an optical disk reproducing apparatus to which the present invention is applied. The optical disc 1 is rotated by the motor 3 at a constant linear velocity, for example. Reading of information recorded on the optical disc 1 is performed by the optical pickup 5. The optical pickup 5 is fixed to a drive coil 7 constituting a movable part of the feed motor 6, and this drive coil 7 is controlled by a feed motor control circuit 8.
[0021]
A permanent magnet (not shown) is provided at a fixed portion of the feed motor 6, and the optical pickup 5 is moved in the radial direction of the optical disk 1 when the drive coil 7 is excited by the feed motor control circuit 8.
[0022]
The optical pickup 5 is provided with an objective lens 10 supported by a wire or a leaf spring (not shown). The objective lens 10 can be moved in the focusing direction (lens optical axis direction) by driving the drive coil 12, and can be moved in the tracking direction (direction orthogonal to the optical axis of the lens) by driving the drive coil 11. Is possible.
[0023]
A light beam is emitted from the semiconductor laser oscillator 19 by the drive control of the laser control circuit 13.
[0024]
A light beam emitted from the semiconductor laser oscillator 19 is irradiated onto the optical disc 1 through the collimator lens 20, the half prism 21, and the objective lens 10. The reflected light from the optical disk 1 is guided to the photodetector 24 through the objective lens 10, the half prism 21, the condenser lens 22, and the cylindrical lens 23.
[0025]
The quadrant photodetector 24 includes photodetection cells 24a, 24b, 24c, and 24d. Among these, the output signal of the photodetection cell 24a is supplied to one end of the adder 26a through the amplifier 25a for current / voltage conversion. The output signal of the light detection cell 24b is supplied to one end of the adder 26b through the amplifier 25b. The output signal of the light detection cell 24c is supplied to the other end of the adder 26a through the amplifier 25c. The output signal of the photodetection cell 24d is supplied to the other end of the adder 26b through the amplifier 25d.
[0026]
Further, the output signal of the photodetection cell 24a is supplied to one end of the adder 26c through the amplifier 25a. The output signal of the photodetection cell 24b is supplied to one end of the adder 26d through the amplifier 25b. The output signal of the light detection cell 24c is supplied to the other end of the adder 26d through the amplifier 25c. The output signal of the photodetection cell 24d is supplied to the other end of the adder 26c through the amplifier 25d.
[0027]
The output signal of the adder 26a is supplied to the inverting input terminal of the differential amplifier OP2, and the output signal of the adder 26b is supplied to the non-inverting input terminal of the differential amplifier OP2. The differential amplifier OP2 outputs a signal corresponding to the difference between both output signals of the adders 26a and 26b, that is, a focus error signal. This signal is supplied to the focusing control circuit 27. The output signal of the focusing control circuit 27 is supplied to the focusing drive coil 12. As a result, the laser beam is controlled to be always just focused on the optical disc 1.
[0028]
The differential amplifier OP1 outputs a tracking error signal TE corresponding to the difference between both output signals of the adders 26c and 26d. This output is supplied to the tracking control circuit 28. The tracking control circuit 28 generates a track driving signal according to the tracking error signal from the differential amplifier OP1.
[0029]
The tracking control circuit 28 generates a track error signal. The tracking control circuit 28 generates a track drive signal in response to the track error signal, drives the drive coil 11 with the track drive signal, and moves the objective lens 10 in the tracking direction. The tracking control circuit 28 has an A / D converter for sampling the track error signal and provides sampling data of the track error signal. The track drive signal used in the tracking control circuit 28 is supplied to the feed motor control circuit 8.
[0030]
The feed motor control circuit 8 includes detection means for detecting the rotation state of the motor, such as the rotation frequency, rotation speed, or rotation direction of the feed motor 6, and uses an output signal from the detection means in the feed motor drive signal circuit. Thus, the feed motor is controlled during track seek. When seeking the target track on the optical disc, the pickup 5 is moved to the target track position by the feed motor control circuit 8. Further, the tracking control circuit 28 drives the drive coil 11 to control the tracking direction position of the objective lens 10 so that the focus point of the objective lens 10 is accurately on the target track.
[0031]
By performing the focusing control and the tracking control, an adder 26e for adding the output signals of the adders 26c and 26d to the sum signal of the output signals of the photodetection cells 24a to 24d of the photodetector 24 is added. The output signal reflects a change in reflectance from a bit or the like formed on the track of the optical disc 1 corresponding to the recording information. This signal is supplied to the data reproduction circuit 18. The data reproduction circuit 18 reproduces the recorded data based on the reproduction clock signal from the PLL circuit 16.
[0032]
The motor control circuit 4, feed motor control circuit 8, laser control circuit 13, PLL circuit 16, data reproduction circuit 18, focusing control circuit 27, tracking control circuit 28, etc. are controlled by the CPU 30 via the bus 29. The CPU 30 performs a predetermined operation using a program recorded in the ROM 32.
[0033]
As will be described later, the tilt control circuit 33 detects the “warp” of the disk 1, that is, the tilt of the recording surface, and outputs a tilt correction signal Tc so that the objective lens 10 tilts.
[0034]
Based on the output signal of the adder 26e, the jitter measuring circuit 34 measures a correction value that minimizes the jitter, and outputs a correction signal Jc that causes the objective lens 10 to follow the recording surface of the disk. The correction signal Jc is input to the tilt control circuit 33.
[0035]
The data presence / absence determination circuit 35 determines whether or not data is recorded on the optical disc 1 based on the output signal from the adder 26e and outputs a data presence / absence determination signal. The data presence / absence determination signal is sent to the tilt control circuit 33. Entered.
[0036]
Motor control circuit 4, thread motor control circuit 8, laser control circuit 13, PLL circuit 16, data reproduction circuit 18, focusing control circuit 27, tracking control circuit 28, tilt control circuit 33, data presence / absence determination circuit 35, jitter measurement circuit 34 Can be configured as a servo control circuit in one LSI chip, and these circuits are controlled by the CPU 30 via the bus 29. The CPU 30 comprehensively controls the optical disk device in accordance with an operation command provided from the host device 37 via the interface circuit 36. The CPU 30 uses the RAM 31 as a work area, and performs a predetermined operation according to a program including the present invention recorded in the ROM 32.
[0037]
Next, details of the tracking control circuit 28 will be described with reference to FIGS.
[0038]
As shown in FIG. 2, the track seek operation by the tracking control circuit 28 drives the feed motor 6 to accelerate the pickup 5 and then moves the pickup 5 at a high speed (coarse seek operation) as shown in FIG. The pickup 5 is controlled so as to decelerate and perform a precise seek operation.
[0039]
FIG. 3 is a detailed block diagram of the tracking control circuit 28. The counter 41 has a tracking error signal TE generated from a light beam reflected from the optical disk as shown in FIG. A track cross sum signal having a phase of 0 ° and a reference clock signal are input, and the moving time of the optical head is detected by counting the number of clock signals for one track period.
[0040]
The movement speed calculation circuit 42 calculates the movement speed from the detection result of the movement time by the counter 41 at the timing when the movement time detection by the counter 41 ends.
[0041]
That is, as shown in FIG. 4, the counter 41 counts the number of clocks for a period required to pass one track on the disc, and the disc track pitch is determined by the disc standard. The moving speed calculation circuit 42 calculates the moving time of the optical head based on the track pitch of the disk and the time required to pass one track.
[0042]
The counter 44 receives the tracking error signal, the track cross sum signal, and the target track number shown in FIG. The counter 44 counts down the input target track number every time the optical head passes one track, and outputs the remaining track number for the target track of the optical head.
[0043]
The target speed calculation circuit 45 calculates the target speed from the number of remaining tracks output from the counter 44.
[0044]
Then, the difference between the movement speed output from the movement speed calculation circuit 42 and the target speed output from the target speed calculation circuit 45 is calculated by the subtraction circuit 46, and the difference value output from the subtraction circuit 46 is sent to the MPU. The feed motor drive voltage control is performed so that the moving speed follows the target speed.
[0045]
The learning table 47 is provided for learning the error between the moving speed and the target speed when decelerating in the fine seek mode operation, and performing data correction to follow the moving speed to the target speed.
[0046]
In other words, the target track number setting value, the seek direction, the number of remaining tracks calculated from the counter 44, and the difference between the moving speed and the target speed output by the subtraction circuit 46 are input to the learning table 47. .
[0047]
In the present embodiment, when the number of remaining tracks with respect to the target track becomes, for example, 200 tracks or less, the operation shifts to the precise seek mode operation. In the learning table 47, as shown in FIG. In each direction (inward and outward of the disk), the difference value between the moving speed and the target speed corresponding to 1 to 200 tracks is stored for each group of the target track setting number as one unit.
[0048]
The learning table is created in accordance with the target track setting number in order to take into account the inertia due to the moving distance, and it is preferable to hold the table for each target track setting number, but the learning table 47 becomes larger. Therefore, one learning table is created as a group of target track setting numbers within a predetermined range.
[0049]
Further, the reason why the table is divided according to the seek direction is to consider the eccentricity due to the moving direction between the inner side and the outer side of the disk.
[0050]
The learning table 47 is cleared as the optical disk is replaced, and performs learning during the seek operation every time a new optical disk is loaded, and stores the difference value between the moving speed and the target speed.
[0051]
In the precise seek mode operation after learning of the learning table 47, after the difference value is calculated by the subtracting circuit 46, the difference between the movement speed and the target speed already stored by the seek performed in the past from the learning table 47. Call value. At this time, the call index is the target track number setting value, the seek direction, and the remaining track number calculated from the counter 44.
[0052]
The error correction circuit 48 is input with the output of the subtraction circuit 46 and the difference value from the learning table 47, and the current difference calculated by the subtraction circuit 46 using the past difference value called from the learning table 47. Error correction is performed on the value, the error-corrected value is sent to the MPU, and feed motor drive voltage control is performed so that the moving speed follows the target speed.
[0053]
The MPU controls the feed motor using a value that takes into account the reaction error of the feed motor in advance by correcting the currently calculated difference value using the past difference value called from the learning table 47. Therefore, the moving speed following the target speed shown in FIG. 2 can be obtained.
[0054]
On the other hand, in the learning table 47, the past difference value and the current difference value calculated by the subtracting circuit 46 are averaged and stored in the called index, or the stored difference value and the current difference value are stored. The difference value in the learning table 47 is updated by replacing the calculated difference value and storing it. The averaging is performed to thin out a rapid change in the moving speed.
[0055]
In FIG. 3, the tracking error signal and the track cross sum signal are input to the phase detection circuit 49, and the edge detection of the tracking error signal and the track cross sum signal is performed as shown in FIG. To detect the phase.
[0056]
Whether the phase detected by the phase detection circuit 49 is determined by the direction detection circuit 50 every time the edge is detected, and the direction previously determined by the reverse detection circuit 51 is compared with the current direction to determine whether the current is reverse. Judging. When it is determined that the vehicle runs backward, an interrupt is notified to the MPU in order to stop seeking.
[0057]
The error range calculation circuit 52 receives the output of the target speed calculation circuit 45, the difference value called from the learning table 47, and the error range setting value.
[0058]
In this error range calculation circuit 52, the speed upper limit value of the pickup head 5 is obtained by adding and subtracting a value obtained by multiplying the difference value called from the learning table 47 by the error coefficient to the output of the target speed calculation circuit 45. In addition, the value of the moving speed error range allowed as the lower limit value is calculated.
[0059]
When the learning table 47 before learning or when the reaction error of the feed motor for causing the moving speed of the head 5 to follow the target speed is known in advance, the above calculation is not used. The speed error range input as the error range setting value can also be set as a parameter.
[0060]
The runaway detection circuit 53 receives the output of the error range calculation circuit 52 and the output of the moving speed calculation circuit 42, and determines whether or not the pickup head 5 is running away. When the pickup head 5 runs away, this detection result is sent to the MPU and the output of the feed motor 6 is stopped.
[0061]
Next, the operation of the tracking control circuit 28 will be described.
[0062]
In the precise seek mode, the target speed output from the target speed calculation circuit 45 is decelerated at a constant rate as shown in FIG. However, due to the inertia of the feed motor 6 and the pickup head 5, the individual difference of the feed motor 6, and the control error caused by the speed detection delay, the actual speed of the pickup head 5 is the pre-correction data indicated by the one-dot chain line in FIG. Thus, an error with respect to the target speed occurs.
[0063]
Since this error generated in the past seek operation is learned in the learning table 47, it is calculated by the subtraction circuit 46 using the past difference value called from the learning table 47 by the error correction circuit 48. Error correction for the current difference value is performed and output to the MPU.
[0064]
As shown in FIG. 6, the correction value is negative when the speed of the pickup head 5 is higher than the target speed, and conversely, when the speed of the pickup head 5 is lower than the target speed, the correction value is positive. Then, by performing the seek operation by controlling the driving voltage of the feed motor with the value corrected by the correction value, the error with respect to the target speed can be reduced as in the corrected data indicated by the solid line in FIG. it can.
[0065]
By correcting the reaction error of the feed motor 6 and the individual difference of the optical disc, the speed of the optical head can be accurately followed to the target speed, and a stable target position can be achieved.
In addition, the total seek time can be shortened by achieving stable target position arrival.
[0066]
Further, by reducing the feed motor reaction error that occurs during the follow-up operation to the deceleration type target speed in the vicinity of the target track, it is possible to suppress the runaway due to the reverse running of the optical head.
[0067]
Further, since the learning table is cleared when the optical disk is replaced, it is possible to reduce the tracking error to the target speed caused by the individual difference of the optical disk.
[0068]
Next, the reverse running detection operation by the reverse running detection circuit 51 will be described.
[0069]
As described above, the tracking error signal and the track cross sum signal are input to the phase detection circuit 49. As shown in FIG. 3, the tracking error signal and the track cross sum signal are detected, and the signals are compared with each other. Thus, the phase detected by the phase detection circuit 49 is determined for each edge detection by the direction detection circuit 50, and the direction previously determined by the reverse running detection circuit 51 and the current direction are determined. A comparison is made to determine whether the vehicle is running backward.
[0070]
The direction detection circuit 50 detects the direction of the optical head 5 by checking the phase detection history when the tracking error signal and the track cross sum signal have n periods after the phase detection by the phase detection circuit 49. To do.
[0071]
This is to compensate for missing pulses in the tracking error signal or the track cross sum signal by detecting the phase before and after. Further, in order to shorten the direction detection time based on the phase detection history, the direction of the optical head may be detected simultaneously with the phase detection without setting the period.
[0072]
The reverse running detection circuit 51 determines whether or not the optical head 5 is running backward based on the output of the direction detection circuit 50. The reverse running detection circuit 51 receives the optical head output from the moving speed calculation circuit 42. 5 and the upper limit value and the lower limit value of the allowable speed of the optical head 5 output from the error range calculation circuit 52 are input.
[0073]
That is, the reverse running detection circuit 51 detects the reverse running of the optical head 5 based on the output history of the direction detection circuit 50, and when the moving speed of the optical head 5 exceeds the allowable speed range, It is determined that 5 is running backward. Thereby, reverse running detection by erroneous phase detection can be thinned out.
[0074]
For example, when the backward running is detected by the direction detection based on the history confirmation and the moving speed of the optical head 5 exceeds the allowable speed range (timing t1) as shown in FIG. It is judged as runaway.
[0075]
The reverse running detection circuit 51 can also thin out erroneous determinations due to missing tracking error signals or track cross sum signals.
[0076]
That is, as shown in FIG. 8, when a tracking error signal pulse is missing (cannot be compensated), the edge detection of the tracking error signal becomes impossible. It is detected that the phase for comparing the edges of the track cross sum signal is opposite (reverse running).
[0077]
However, as described above, the reverse running detection circuit 51 detects the backward running of the optical head 5 based on the output history of the direction detection circuit 50, and the moving speed of the optical head 5 exceeds the allowable speed range. In this case, it is determined that the optical head 5 is running backward.
[0078]
Therefore, even if the tracking error signal or the track cross sum signal pulse is lost, the reverse running detection circuit 51 does not determine that the optical head 5 is running backward if the moving speed of the optical head 5 is a normal speed within the allowable range. . For this reason, reverse running detection by erroneous phase detection can be thinned out.
[0079]
It is also possible to perform reverse run detection only by detecting the direction by the above phase detection without performing the runaway detection by calculating the speed error due to factors such as the variation of the track pitch and the operation considering the preceding process. In this case, the time for checking the history is shortened, and the direction can be detected quickly.
[0080]
The detection result of the reverse running detection circuit 51 is sent to the MPU, and the output to the feed motor is stopped. When the speed at which the truck can be pulled in is reached, the mode is changed from the seek mode to the brake mode, and the truck is pulled in.
[0081]
When reverse running is detected from the output of the direction detection circuit 53, the reverse running detection circuit 51 determines and controls whether it is determined that the runaway is detected and the track pull-in is detected or the normal operation is determined and the seek is continued. When traveling, it is possible to reach the target position while minimizing the reverse travel of the optical head. Under normal conditions, it is possible to prevent the seek from being stopped due to a malfunction.
[0082]
With the above reverse running detection circuit 51, the total seek time can be shortened by minimizing the reverse running and reaching the vicinity of the target position.
[0083]
Next, the runaway detection operation by the runaway detection circuit 53 will be described.
[0084]
Usually, when the optical head 5 is accelerated while the optical head 5 is decelerated by the feed motor 6, or when the optical head 5 is decelerated while the optical head 5 is accelerated, it is caused by some abnormality. It is detected that the optical head 5 is running away.
[0085]
However, in the precision seek mode operation, the feed motor 6 is controlled so that the acceleration and deceleration of the optical head 5 are finely controlled to reach the target track, so that the reaction error and speed detection delay of the feed motor 6 are controlled. Therefore, there is a risk that the optical head 5 is detected as running out of control.
[0086]
After the speed calculation by the moving speed calculation circuit 42 and the speed calculation by the target speed calculation circuit 45, the learning table 47 is set using the input target track number setting value and seek direction and the remaining track number calculated from the counter 44 as indexes. The difference value between the moving speed and the target speed already stored by the seek performed in the past is called.
[0087]
The error range calculation circuit 52 calculates a speed error range by obtaining a value obtained by multiplying the difference value called from the learning table 47 by an error coefficient.
[0088]
Then, the value of the speed error range is added to or subtracted from the target speed that is the output of the target speed calculation circuit 45. Thereby, as shown in FIG. 9, the upper limit value and the lower limit value (shown by the one-dot chain line in FIG. 9) of the allowable speed with respect to the target speed (shown by the chain line in FIG. 9) of the optical head 5 are calculated. It becomes.
[0089]
In the runaway detection circuit 53, is the moving speed of the optical head 5 output from the moving speed calculation circuit 42 within the range between the upper limit value and the lower limit value of the allowable speed of the optical head 5 output from the error range calculation circuit 52? By determining whether or not, it is determined whether or not the optical head 5 is running away.
[0090]
In the example shown in FIG. 9, there is a period in which the moving speed (indicated by the solid line in FIG. 9) of the optical head 5 output from the moving speed calculation circuit 42 is accelerating despite being decelerating. ing. The moving speed during this acceleration period exceeds the previous value, but the moving speed is within the allowable speed range, and at this point, the runaway detection circuit 53 does not determine that the runaway has occurred. When the moving speed of the optical head 5 (indicated by the solid line in FIG. 9) exceeds the previous value and the moving speed of the optical head 5 of the optical head 5 exceeds the allowable speed range (timing t2), the runaway detection circuit 53 is judged as a runaway.
[0091]
Therefore, it is possible to thin out the runaway detection due to a simple movement speed error.
[0092]
In addition, when the reaction error of the feed motor for causing the moving speed to follow the target speed is known in advance, or at the timing before learning of the learning table 47, the speed error set from the outside without using the above calculation. The range may be set as a parameter of the error range calculation circuit 52.
[0093]
The detection result of the runaway detection circuit 53 is sent to the MPU, and the output of the feed motor 6 is stopped. When the speed at which the truck can be pulled in is reached, the mode is changed from the seek mode to the brake mode, and the truck is pulled in.
[0094]
In addition, when acceleration is detected during deceleration in the precise seek mode operation, the runaway detection circuit 53 determines and controls whether it is determined that the runaway has occurred and the transition is made to the track pull-in or the normal operation is continued. In the case of runaway, it is possible to reach the vicinity of the target position while minimizing the runaway of the optical head, and in the normal state, stoppage of seek due to malfunction can be suppressed.
[0095]
Furthermore, in the past, acceleration was determined on the MPU side based on the speed detection result, but by setting a parameter in advance, the runaway detection circuit 53 determines runaway detection, thus reducing the MPU processing. By shortening the processing time, the runaway of the optical head can be minimized.
[0096]
Therefore, the total seek time can be shortened by minimizing the runaway by the runaway detection circuit 53 and reaching the vicinity of the target position.
[0097]
【The invention's effect】
As described above, according to the present invention, it is possible to provide an optical disc apparatus capable of performing a precise seek operation at high speed and stably without using a speed sensor.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an optical disc apparatus according to the present invention.
FIG. 2 is a velocity transition diagram for explaining a seek mode.
3 is a block diagram for illustrating a configuration of a tracking control circuit 28 in the optical disc apparatus of FIG. 1;
FIG. 4 is a waveform diagram for explaining the operation of the tracking control circuit 28;
FIG. 5 is a table for explaining details of a learning table 47;
FIG. 6 is a diagram for explaining the effect of error correction based on a learning table 47;
FIG. 7 is a view for explaining the action of runaway detection of the optical head 5;
FIG. 8 is a view for explaining the action of runaway detection of the optical head 5;
FIG. 9 is a waveform diagram for explaining the operation of the reverse running detection circuit 51 when a pulse is missing.
[Explanation of symbols]
5 …… Optical head
6 ... Feed motor
28 …… Tracking control circuit
47 …… Learning table
43 …… Speed detection delay compensation circuit
48 …… Error correction circuit
49 …… Phase detection circuit
50 …… Direction detection circuit
51. Reverse running detection circuit
53 …… Runaway detection circuit

Claims (8)

In an optical disk device that reads data recorded on a track on an optical disk by moving an optical pickup by a feed motor,
Speed calculating means for calculating the moving speed of the optical pickup based on a tracking error signal generated from the optical pickup when traversing the track of the optical disc;
Means for learning the target speed of the optical pickup and the error speed of the moving speed corresponding to the number of remaining tracks when the number of remaining tracks with respect to the target number of moving tracks of the optical pickup is less than the predetermined number of tracks and decelerating the optical pickup; ,
An optical disc apparatus comprising: means for controlling the feed motor using the error speed learned by the learning means. The optical disk apparatus according to claim 1, wherein means for calculating an allowable range of the moving speed of the optical pickup using the error speed learned by the learning means;
An optical disc comprising: a runaway detection means for detecting a runaway of the optical pickup by comparing the allowable range calculated by the calculation means with the moving speed of the optical pickup calculated by the speed calculation means. apparatus. The optical disc apparatus according to claim 2, wherein direction detecting means for detecting a moving direction of the optical pickup;
A reverse running detecting means for detecting reverse running of the optical pickup based on a change in the detection result by the direction detecting means, and the reverse running detecting means has a moving speed of the optical pickup calculated by the speed calculating means as described above. When it is within the allowable range calculated by the calculating means, it is not determined that the optical pickup is running backward, and when the moving speed of the optical pickup exceeds the allowable range calculated by the calculating means, the direction detecting means An optical disc apparatus, wherein the reverse running of the optical pickup is determined based on a change in a detection result by the optical disc. In an optical disk device that reads data recorded on a track on an optical disk by moving an optical pickup by a feed motor,
Speed calculating means for calculating the moving speed of the optical pickup based on a tracking error signal generated from the optical pickup when traversing the track of the optical disc;
Means for learning the target speed of the optical pickup and the error speed of the moving speed in correspondence with the number of remaining tracks with respect to the target number of moving tracks and the moving direction of the optical pickup;
An optical disc apparatus comprising: means for controlling the feed motor using the error speed learned by the learning means. In a seek method for an optical disk apparatus that reads data recorded on a track on an optical disk by moving an optical pickup by a feed motor,
A speed calculating step for calculating a moving speed of the optical pickup based on a tracking error signal generated from the optical pickup when traversing a track of the optical disc;
Learning the target speed of the optical pickup and the error speed of the moving speed corresponding to the number of remaining tracks when the number of remaining tracks with respect to the target number of moving tracks of the optical pickup is less than the predetermined number of tracks and decelerating the optical pickup; ,
A seek control method for an optical disc apparatus, comprising: controlling the feed motor using the error speed learned in the learning step. 6. The seek method for an optical disk device according to claim 5, wherein the allowable range of the moving speed of the optical pickup is calculated using the error speed learned in the learning step;
An optical disc comprising a runaway detection step for detecting runaway of the optical pickup by comparing the allowable range calculated in the calculation step with the moving speed of the optical pickup calculated by the speed calculation means. Device seek control method. 7. The seek method for an optical disk device according to claim 6, wherein a direction detecting step for detecting a moving direction of the optical pickup;
A reverse running detection step for detecting the reverse running of the optical pickup based on a change in the detection result of the direction detection step, and in the reverse running detection step, the moving speed of the optical pickup calculated in the speed calculating step is If it is within the allowable range calculated in the calculation step, it is not determined that the optical pickup is running backward, and if the moving speed of the optical pickup exceeds the allowable range calculated in the calculation step, the direction detection step A seek control method for an optical disc apparatus, wherein the optical pickup is determined to run backward based on a change in a detection result by the optical disc. In a seek method for an optical disk apparatus that reads data recorded on a track on an optical disk by moving an optical pickup by a feed motor,
A speed calculating step for calculating a moving speed of the optical pickup based on a tracking error signal generated from the optical pickup when traversing a track of the optical disc;
Learning the target speed of the optical pickup and the error speed of the moving speed corresponding to the number of remaining tracks with respect to the target number of moving tracks and the moving direction of the optical pickup;
And a step of controlling the feed motor using the error speed learned in the learning step.

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