JPH02113436A - optical disc device - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an optical disc device.

[Conventional technology]

Conventionally, optical disk devices were manufactured using materials published by the Institute of Electrical Communication Engineers, MR,! 15
-32 "Tracking Servo System for Small Optical Disc Device" etc., and FIG. 4 shows an example thereof.

In this optical disc device, an optical disc 1 is rotationally driven by a motor, and when recording information, an optical head 2 reflects a strong laser beam emitted from a semiconductor laser 3 through an optical system 4 with a half mirror 5, and an objective lens 6 directs the optical disc 1 into the optical disc. Information is recorded on the tracks of the optical disc 1 by focusing the light onto the optical disc 1 as a light spot. When reproducing information, the optical head 2 tracks the optical disc 1 by irradiating the optical disc 1 with a weak laser beam emitted from the semiconductor laser 3 and receiving the reflected light by the light receiving element via the objective lens 6. Get more information. Further, the laser beam reflected by the optical disk 1 is detected by a track detector 7 via an objective lens 6 and a half mirror 5, and an output signal from the track detector 7 is taken out via a track detection amplifier 8 as a track signal. This track signal is generated every time the light spot crosses a track on the optical disc 1. Normally, when recording or reproducing information, a track signal from a track detection amplifier 8 is amplified by an amplifier 9 and applied to a tracking actuator 11 by a switch 10.
moves the objective lens 6 in the radial direction of the optical disc 1 to perform tracking so that the light spot coincides with the track on the optical disc 1. At this time, the position of the objective lens 6 is detected by a lens position detector 12, and the output signal of this lens position detector 12 is amplified by an amplifier 13 and applied to a positioner 14 consisting of a seek motor.

Therefore, the seek motor 14 moves the optical head 2 so that the optical axis of the objective lens 6 does not shift according to the movement of the objective lens 6.
move the whole thing.

During seek (track access), the optical head 2 is driven in the radial direction of the optical disc 1 by the seek motor 14 until the optical spot reaches the target track on the optical disc 1. At this time, at the same time as the start of seek, F F F D H <-2> is loaded into the up/down counter 15, and the number of tracks to be moved by the optical head 2 is 1/2, for example, the optical head 2 is moved to 512 tracks. If it is moved by that amount, 1/2 of that amount, 256, is loaded into the comparator 17 by the microcomputer (CPU) 16, and the counter 15 starts counting down the track pulses from the binarization circuit 18. Here, the track signal from the track detection amplifier 8 is binarized by the binarization circuit 18 to become a track pulse, and this track pulse is input to the counter 15. The count value of the counter 15 is converted into speed data by a read-only memory (ROM) 19, and this speed data has a value proportional to the square root of the residual distance determined from the count value of the counter 15. This speed data from the ROM 19 is converted into an analog value by a digital/analog (D/A) converter 20 and becomes a reference speed signal. Further, a speed detector 21 consisting of a frequency/voltage converter detects the moving speed of the objective lens 6 by converting the frequency of the track pulse from the binarization circuit 18 into a voltage. The speed signal from the speed detector 21 is compared with the reference speed signal from the D/A converter 20 in a comparator 22 to detect the deviation, and the output signal from the comparator 22 is amplified by an amplifier 23. When the signal is applied to the tracking actuator 11 by the switch 24, the objective lens 6 is driven by the tracking actuator 11, and the speed of the objective lens 6 is controlled.

Comparator 17 compares the loaded number with the count value of counter 15, and if they match, counter 1
5 to count up mode. therefore,
The counter 15 counts up the track pulses from the binarization circuit 18. Thereafter, when the count value of the counter 15 reaches FFFEH<-1>, an interrupt is applied to the CPU 16, and the CPU 16 ends the seek operation. Therefore, the moving speed of the objective lens 6 gradually increases from the start of the seek at a constant acceleration, and
It is controlled so that it gradually decreases from point 2.

The signals at the end of the seek are as shown in FIG. 3, and the speed of the objective lens 6 is controlled to a constant settling speed vs from several tracks before the end point of the seek (target track). This settling speed vs generates reference speed information R
Determined by OM19 data. When the counter 15 finishes counting the number of tracks to be moved by the optical head 2, the objective lens 6 must stop moving and shift to a mode for tracking the target track.

Therefore, from the time when the counter 15 finishes counting the number of tracks to be moved by the optical head 2 (A in FIG. 2), the switch 25 or 26 is closed for a certain period of time t, and the reference voltage (+Vref, -Vref) is set. A more positive or negative brake pulse is created, which causes tracking actuator 1
Added to 1. The amplitude of this brake pulse is determined by the reference voltage V raf, and energy determined by this reference voltage V ref and the above-mentioned time t is applied to the objective lens 6 in a direction opposite to its moving direction, thereby canceling out the settling speed Vs. It will be done. After the speed of the objective lens 6 becomes almost zero, the switches 24, 25,
26 is turned off and switch 10 is turned on to enter tracking mode.

[Problem to be solved by the invention]

As shown in FIG. 5, when the above-mentioned optical disk device 27 is installed tilted, a difference occurs in the thrust (energy) required for the objective lens 6 in the theta direction due to the influence of gravity, resulting in an error in speed control of the objective lens 6. occurs, and the theta direction (from the inner circumferential side to the outer circumferential side of the optical disc 1, or from the outer circumferential side to the inner circumferential side)
The magnitude of the settling speed V5 differs depending on the speed. Vref
Since and t are constant, the energy of the brake pulse is constant. For this reason, if the settling speed V becomes different from the set value, the speed of the objective lens 6 after braking will not become zero, and the track will not be pulled in (the light spot will not match the target track), resulting in a tracking mode. I can't enter it,
Tracking will be lost.

This phenomenon also occurs when a disturbance such as vibration is applied during seek settling. Further, although it is possible to reduce the speed control error by increasing the loop gain of the speed control, there is a limit to the loop gain due to resonance of the mechanical system.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical disk device that eliminates the above-mentioned drawbacks and is capable of performing stable seek operations even when the disk device is tilted or when a disturbance is applied during seek settling.

[Means to solve the problem]

In order to achieve the above object, the present invention provides an optical head 101 that records and/or reproduces information by irradiating a light beam as a light spot onto an optical disk, as shown in FIG. A track signal generating means 102 generates a fixed number of track signals each time the reflected light crosses a track on the optical disk, and a light flux fine movement member is moved by the track signal from the track signal generating means 102 to move the light flux finely moving member to move the light flux finely moving member to move the light flux finely moving member. A tracking drive means 103 that moves the light irradiation position in the radial direction of the optical disc, a counting means 104 that counts the track signals from the track signal generating means 102, and a counting means 104 that counts the track signals from the track signal generating means 102, and a count value of the counting means 104 according to the count value of the counting means 104. a reference speed information generating means 105 for generating reference speed information of the optical spot proportionally corresponding to an absolute value; a speed detecting means 106 for detecting the moving speed of the optical spot from the frequency of the track signal; a speed control means 107 that compares the output signal of the means 106 with the reference speed information and controls the tracking drive means 103 based on the result;
The optical disc device includes a seek means 108 for moving the light spot to a target position on the optical disc, the speed at which the light spot ends moving is detected from the output signal of the counting means 104, and the light beam The present invention is provided with a correction means 109 for correcting the difference in speed at the end of the movement operation depending on the direction of movement.

[For production]

The optical head 101 irradiates the optical disc with a light beam as a light spot to record and/or reproduce information, and each time the reflected light from the optical disc to the optical head 101 crosses a track on the optical disc, a certain number of A track signal is generated by track signal generating means 102. Based on the track signal from the track signal generating means 102, the tracking drive means 103 moves the light flux fine movement member to move the light irradiation position of the optical disk in the radial direction of the optical disk, and the track signal generating means 102
The counting means 104 counts the track signals from the . In accordance with the count value of the counting means 104, the reference speed information of the light spot proportionally corresponding to the absolute value of the count value is generated by the reference speed information generation means 105, and the speed detection means 106 generates the reference speed information of the optical spot that corresponds proportionally to the absolute value of the count value. The moving speed of the light spot is detected from . Speed control means 10
7, the output signal of the speed detection means 106 and the reference speed information are compared, and based on the result, the tracking drive means 103 is controlled during seek to control the speed of the light spot, and the seek means 108 controls the speed of the light spot. It is moved to a target position on the optical disc. Then, a correction means 109 detects the speed of the light spot at the end of the moving operation from the output signal of the counting means 104, and corrects the difference in the speed at the end of the moving operation depending on the moving direction of the light beam.

〔Example〕

FIG. 2 shows an embodiment of the invention.

This embodiment is applied to the above-mentioned optical disc device.

CPU16. CPU2g, RO instead of ROM19
It is equipped with an M29° RAM 30, and the same parts as those of the optical disk device described above are given the same reference numerals and their explanation will be omitted.

Generally, the number of tracks on an optical disc is very large (51/4
20,000 optical discs), the output of the up/down counter 15 is data of 10 bits or more. Among this data, it is the lower bits that are related to the settling speed. The speed data corresponding to the upper bits of the output of the down counter 15 (speed data when there are many remaining counts) is generated in the ROM 29 as in the past, and the speed data corresponding to the lower bits of the output of the up/down counter 15 (speed data when there are many remaining counts) is generated. The speed data (when the count number is small) is generated in RAM30, and this RAM
The contents of M30 are made to be rewritten by CPUZ8. Further, the lower bit data of the up/down counter 15 is sent to the CPUZ8, and the CPU2g measures the settling time vs in FIG. 3 using a built-in timer.

For example, if the number of tracks in the settling section on the optical disk corresponding to the settling time vs is set to 10, from the time when the number of remaining tracks counted by the up/down counter 15 reaches 10 to the time when the number of remaining tracks reaches 0 The number of reference clocks is counted by a timer.

This optical disk device performs a seek test from the inner circumference to the outer circumference and from the outer circumference to the inner circumference of the optical disk 1 when the power is turned on or periodically. ! Measure constant time vs. If the settling time V is longer than the design value, the settling speed V8 is slow, and if the settling time V is shorter than the design value, the settling speed V is fast. The CPU 2g rewrites the contents of the RAM 29 according to the measured settling speed v, that is, if the settling speed v is slow, the D/A converter 20
RAM so that the output of
Rewrite the contents of 29, and if the settling speed v is fast, D
The contents of the RAM 29 are rewritten to correct the reference speed voltage so that the output of the /A converter 20 becomes lower.

In this way, the CPU 28 performs the seek test several times while correcting the reference speed voltage, and determines the settling speed V from the inner circumference to the outer circumference and from the outer circumference to the inner circumference of the optical disc 1.

so that they are approximately equal.

FIG. 6 shows the seek test routine of the CPU 28.

When performing a seek test, the CPUZ8 first moves the optical head 2 to the home position (for example, the optical disk 1) by a seek operation.
6th CPU2 to be moved to the innermost track of
8 is the initial speed data V stored in the RAM 30 in step a. o
ut is written, and a seek operation to the outermost track of the optical disc 1 is performed as described above. In this case, the up/down counter 15 is loaded with a value corresponding to the stroke from the innermost track to the outermost track of the optical disc 1, and counts track pulses from the binarization circuit 18.

The CPU 28 reads the lower data (number of remaining tracks) n output from the up/down counter 15, and determines whether this n has reached the settling interval and reached IO. If n does not reach 10, the CPU 28 repeats this operation until n reaches 1.
If it reaches 0, the CPU 28 causes the timer to start counting the reference clock in step b, thereby increasing the settling time T.
The measurement of out is started, and then, by detecting that n becomes 0, it is detected that the seek operation to the outermost track has ended, and the timer is stopped to end the measurement of the settling time Tout. Next, the CPU 2g stores the initial speed data V in the RAM 30 in step C. in is written, and a seek operation from the outermost track to the innermost track of the optical disc 1 is performed as described above. In this case, the up/down counter 15 is loaded with a value corresponding to the stroke from the outermost track to the innermost track of the optical disc 1, and counts track pulses from the binarization circuit 18. The CPU 28 determines whether n has reached the settling interval and reached 10, and if n does not reach 10, the CPU 28
8 repeats this operation, and when n reaches 10, C
In step d, PUZ8 starts measuring the settling time Tin by causing the timer to start counting the reference clock, and then detects that n has become O, thereby completing the seek operation to the innermost track. The primary CPU Z8 detects this and stops the above-mentioned timer to end the measurement of the settling time Tin.
By determining whether the absolute value of the difference between ut and Tin is less than or equal to a certain value A, it is determined whether the settling times Tout and Tin are substantially equal. Settling time Tout.

If Tin is substantially equal, determine the settling time Tout and the magnitude of Tin. If the settling time Tout is greater than the settling time Tin, in step e, the speed data V in the RAM 30,
After correcting the settling times Tout and Tin by increasing out and decreasing the speed data V and in of the RAM 30, the process returns to step a. Also, CPU2g has a settling time T
If aut is smaller than the settling time Tin, the speed data v and out of the RAM 30 are decreased in step f, and the speed data v and out are stored in the RAM 30.
After correcting the settling times Tout and Tin by increasing the speed data Vllin of 30, the process returns to step a. If the settling times Tout and Tin are approximately equal, CPU2
8 ends the seek test.

Specifically, in steps a and c above, as shown in FIG.
Write to M30 and save the speed data VaO to internal memory.
ut or V. Remember in.

In steps b and d above, specifically, as shown in FIG. 8, the CPO 28 causes the built-in timer to start counting the reference clock at the start of measuring the settling time T out or Tin.
At the end of the seek, the timer is stopped, the timer value is read, and the measurement of the settling time Tout or Tin is completed.

In steps e and f above, specifically, as shown in FIG. 9, the CPU 2g reads the speed data v, Out, V in the internal memory.
, in V . or V so that out increases and Vllin decreases. out decreases and V. Rewrite so that in increases, and the speed data V0out, Vain
is read and written into the RAM 30.

In a normal seek operation, the CPU 28 uses speed data V in the internal memory as shown in FIG. Out and Voin are read and written into the RAM 30, and a seek operation is performed as described above. In this case, the RAM 30 is accessed by the lower data of the output of the up/down counter 15 and reads out the speed data V, out, V, in.

FIG. 11 shows another embodiment of the invention.

In this embodiment, the CPU 2g uses the speed data V in the internal memory in the above embodiment. out, V, and in are read out according to the lower data of the output of the up/down counter 15 and output to the D/A converter 31, and the output signal of this D/A converter 31 is sent to the D/A converter by the adder 32. 31 and sent to the comparator 22. CPU
28 is the same as the above embodiment in that it measures the settling speed by reading the lower data of the output of the up/down counter 15 during the seek test, and instead of writing the speed data to the RAM 30, the CPU 28 has a data holding function (with a latch). D of
The speed data is sent to the /A converter 31 and latched.

In the above embodiment, an objective lens is used as a light flux fine movement member for moving a light spot, but the present invention can also be applied to an optical disk device of a type in which a galvanomirror 34 is driven to move a light spot, as shown in FIG. can be applied similarly. In this case, the light source 35 and the position detector 36
Galvano mirror with mirror angle detector composed of
By detecting the angle of 34, the amount of movement of the optical spot (the amount of optical axis deviation) is detected, and the output signal is sent to the amplifier 13.
is sent to the seek motor 14 via.

〔Effect of the invention〕

As described above, according to the present invention, there is provided an optical head that records and/or reproduces information by irradiating a light beam as a light spot onto an optical disc, and a light beam reflected from the optical disc to the optical head tracks a track on the optical disc. a track signal generating means for generating a fixed number of track signals each time the track signal is traversed; and a light beam fine movement member is moved by the track signal from the track signal generating means to move the light irradiation position of the optical disk in the radial direction of the optical disk. tracking drive means; a counting means for counting track signals from the track signal generating means; and a reference velocity information of the light spot proportional to the absolute value of the counted value according to the counted value of the counting means. a reference speed information generating means for generating; a speed detecting means for detecting the moving speed of the optical spot from the frequency of the track signal; and a comparison between the output signal of the speed detecting means and the reference speed information, and based on the result, the An optical disk device comprising a speed control means for controlling a tracking drive means and a seek means for moving the light spot to a target position on the optical disk, wherein the speed at the end of the moving operation of the light spot is measured by the counting means. Since it is equipped with a correction means that detects from the output signal and corrects the difference in the speed at the end of the movement operation depending on the direction of movement of the light beam, the settling speed will not change if it is tilted or if a disturbance is applied during seek settling. However, the settling speed can be corrected, and stable seek operations can be performed.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the present invention, FIG. 2 is a block diagram showing an embodiment of the present invention, FIG. 3 is a timing chart of a conventional optical disc device, and FIG. 4 is a block diagram showing the same optical disc device. FIG. 5 is a schematic diagram showing the tilted state of the above embodiment, FIG. 6 is a flowchart showing the seek test routine of the CPU in the above embodiment, and FIGS.
10 is a flowchart showing the normal operation of the CPU, FIG. 11 is a block diagram showing another embodiment of the present invention, and FIG. 12 is a block diagram showing other embodiments of the present invention. FIG. 2 is a schematic diagram showing a part of an embodiment of the invention. 101... Optical head, 102... Track signal generating means, 103... Tracking drive means, 104...
- Counting means, 105...Reference speed information generation means, 10
6...Speed detection means, 107...Speed control means, 1
0g... Seek means, 109... Correction means. Figure 4 Figure 2 Figure 2

Claims (1)

[Claims] an optical head that records and/or reproduces information by irradiating a light beam as a light spot onto an optical disk; and a fixed number of track signals each time a reflected light from the optical disk to the optical head crosses a track on the optical disk. a tracking drive means for moving a light beam fine movement member to move a light irradiation position of the optical disk in a radial direction of the optical disk by using a track signal from the track signal generation means; a counting means for counting track signals from the counting means; a reference speed information generating means for generating reference speed information of the light spot proportionally corresponding to the absolute value of the counted value according to the counted value of the counting means; speed detection means for detecting the moving speed of the optical spot from the frequency of the track signal; speed control means for comparing the output signal of the speed detection means with the reference speed information and controlling the tracking drive means based on the result; , a seek means for moving the light spot to a target position on the optical disc, the speed of the light spot at the end of the moving operation being detected from the output signal of the counting means to determine the speed of the light beam. An optical disc apparatus characterized by comprising a correction means for correcting the difference in speed at the end of the movement operation depending on the direction of movement.