JPH09161422A - Retrieval control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably and quickly measure a drive load without causing the drive load and the drive sensitivity of a driving means from scattering when measur ing the driving load of the traveling means. SOLUTION: The retrieval control device moves a site for reading between two arbitrary points on a recording medium 1 at the time of initialization before starting the operation in one direction or in both directions with acceleration/ deceleration speed characteristics having a constant-speed period and compensates the feed forward signal of a feed forward table 35 based on the drive sensitivity and the driving load detected at the move. The reading site is moved with a speed servo so that the move up to the reproduction position of a track forms a specific speed profile according to a corrected feed forward signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording / reproducing apparatus for recording / reproducing information on / from an optical recording medium such as an optical disk, a magneto-optical disk, an optical card, etc., and more particularly to an improvement of its search control system. .

[0002]

2. Description of the Related Art As a control for searching a track of an optical information recording / reproducing apparatus for recording / reproducing information on / from an optical recording medium such as a conventional optical disc, magneto-optical disc, optical card, etc. Actuator access control device (search control device) disclosed in Japanese Laid-Open Patent Publication No. 62-189514
Is disclosed.

This actuator access control device is
A moving means including a power amplifier that moves an electric current through a coil of an actuator, a position detection circuit and a speed detection circuit that detect a position and a moving speed by a position sensor, and a speed signal (voltage) detected by the speed detection circuit. The constant speed from the outside that defines the target speed is compared, and the resulting reference speed information is fed back to the management device.

With such a configuration, it becomes possible to automatically optimize the correction voltage or current for vane-bang control drive voltage or current switching point and friction, external force, etc., with respect to variations in individual actuators. .

[0005]

However, as a problem in the above-mentioned conventional search control device, when the traveling load of the moving means is measured, the traveling means is driven by the feed forward signal, so that the traveling load is When it is extremely small or when the sensitivity of the sensor is extremely large, there is a risk that the moving means may overshoot the target track or, in some cases, runaway.

Further, when the deviation between the target speed and the actual moving speed of the moving means based on the reference speed information is large, it is necessary to measure the traveling load a plurality of times, which takes time. Therefore, an object of the present invention is to provide a search control device capable of measuring a traveling load stably and in a short time without depending on variations in the traveling load and the driving sensitivity of the traveling device when measuring the traveling load of the traveling device. To do.

[0007]

In order to achieve the above object, the present invention has a reproducing means for reading and reproducing an information signal recorded on a recording medium and a track on the recording medium in a substantially width direction of a track. Moving means for moving and arranging the reading portion of the reproducing means to a track desired to be read, and transfer control is performed by a speed servo that adds a feed forward signal to the drive signal of the moving means to control the desired track. In the search control device for searching, the speed servo is applied so that the movement to the track desired to be read has a predetermined speed profile that accelerates to a predetermined target value and decelerates to stop at the track position. A component that causes an error in the feed-forward signal for performing the speed servo based on the drive signal for driving the moving means, Then, there is provided a correction means for correcting so as to minimize an error component caused by a change or variation in the driving sensitivity of the moving means, the traveling load, etc., and the moving means is driven at least before the search is started. A search control device is provided which corrects subsequent movements of the moving means based on the correction value obtained by the correcting means.

The search control device having the above-described structure has a constant speed period by moving one of the reading parts to one or both by the moving means between two arbitrary points on the storage medium at the time of initialization before starting the operation. The vehicle is moved with such acceleration / deceleration speed characteristics, the drive sensitivity and / or the traveling load of the moving means detected during the movement is obtained, a correction value based on these is obtained, and the feed forward signal is corrected. The corrected feed-forward signal is used to move the track to the reproduction position by applying a speed servo so as to obtain a predetermined speed profile.

[0009]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows the configuration of a search control device according to a first embodiment of the present invention, which will be described.

This search control device is equipped with a recording medium 1 on which information is recorded, a motor 2 for giving rotation by a drive circuit (not shown), a light source 3 including a semiconductor laser for generating a light beam, and the like. Collimator lens 4 for irradiating a light beam to form an optical path for reading information from the recording medium 1, polarizing beam splitter 5, quarter wave plate 6, total reflection mirror 7, objective lens 8, leaf spring 10, tracking An optical system including an actuator 11 and a coil 12, and photoelectrically converting an optical signal formed by the optical system 2
The split photodetector 9 and amplifiers 13 and 14 for amplifying the two outputs generated by the photodetector 9, respectively.
A differential amplifier 15 for outputting a signal corresponding to the difference between the output signals of the amplifiers 13 and 14, a phase compensation circuit 16 for compensating the phase of the output signal of the differential amplifier 15, and a selected and phase-compensated signal. A drive circuit 18 for amplifying a signal and applying it to the coil 12, and a track crossing detector 29 for outputting a track crossing pulse from an output signal of the differential amplifier 15,
An adder circuit 19 for adding the output signals of the amplifiers 13 and 14 to generate an address read signal, and a control circuit 37 for controlling the address and the like of the track to be read and each component part.
A control unit 20 including a feed forward table 35 and a speed profile table 36, and an address input device 21 for designating a desired track address (N0).
A DAC 22 that outputs a target speed instruction under the control of the control unit 20, a speed detection circuit 30 that detects a speed from a track crossing pulse, and a differential that outputs a signal corresponding to the difference between the speed detection signal and the target speed. Amplifier 31 and differential amplifier 3
1 for compensating the phase of the output signal of No. 1, a DAC 23 for outputting a signal based on the feed forward signal from the control unit 20 to the addition circuit 33, and a drive circuit opened and closed under the control of the control unit 20. It is composed of switches 17, 25, and 26 for selecting a signal for controlling 18.

The operation of each part of the search control device thus configured will be described. The recording medium 1 is attached to the rotating shaft of a motor 2 and rotated at a predetermined rotation speed. A light beam generated from a light source 3 such as a semiconductor laser is collimated by a collimator lens 4, then passes through a polarization beam splitter 5 and a quarter-wave plate 6, is reflected by a total reflection mirror 7, and is an objective lens. It is converged and irradiated on the recording medium 1 by 8.

The reflected light of the light beam reflected from the recording medium 1 passes through the objective lens 8, is reflected by the total reflection mirror 7, passes through the quarter wavelength plate 6, and is then reflected by the polarization beam splitter 5. , Is irradiated onto the photodetector 9. The objective lens 8 is attached to a tracking actuator 11 via a leaf spring 10. A focus control system (not shown) performs focus control so that the light beam emitted onto the recording medium 1 is always in a predetermined converged state.

The tracking actuator 11 is
It is composed of a total reflection mirror 7, a coil 12, and a permanent magnet (omitted) attached to a device frame (omitted). When an electric current is passed through the coil 12, the objective lens 8 is recorded on the recording medium by an electromagnetic force received by the coil 12. 1 is applied in the radial direction, that is, in the width direction of the track on the recording medium 1.

Further, the light source 3, the collimator lens 4, the polarization beam splitter 5, the quarter wavelength plate 6 and the photodetector 9 are provided.
The top is fixed to the device frame. The photodetector 9 has a two-divided structure, and the outputs are input to the amplifiers 13 and 14, respectively. The signals of the amplifiers 13 and 14 are input to the differential amplifier 15, and the differential amplifier 15 outputs a signal according to the difference between the two signals. This differential amplifier 15
Signal is a signal indicating the positional deviation between the light beam focused on the recording medium 1 and the track, that is, a track error signal.

The output signal of the differential amplifier 15 is a phase compensation circuit 1 for compensating the phase of the tracking control system.
6, switch 17, and drive circuit 18 for power amplification
Is added to the coil 12 via. Therefore, the objective lens 8 is driven according to the signal from the differential amplifier 15, and tracking control is performed so that the light beam focused on the recording medium 1 is always positioned on the track. Switch 17
Is for disabling tracking control.

Here, a search for desired tracking will be described. The adder circuit 19 includes amplifiers 13 and 1
The output signals of 4 are added, and the added signal is sent to the control unit 20 as an address reading signal. When the address (N0) of the desired track is input to the address input device 21, the control unit 20 reads the address (N1) of the track where the light beam on the recording medium 1 is located, (N0-
N1) is calculated, and a target speed instruction is read from the speed profile table 36 provided inside the control unit 20 and output to the DAC 22 according to the distance and direction to the desired track, and a feed provided inside the control unit 20 is also read. -The feed forward signal is read from the forward table 35 and output to the DAC 23.

At the same time, the control unit 20 opens the switch 17 through the line 24 to disable the tracking control, and brings the switch 25 through the line 27 and the switch 16 through the line 28 into conduction. .

Thereafter, the control unit 20 counts the track crossing pulses output from the track crossing detector 29 in the output signal of the differential amplifier 15, and outputs the target speed instruction from the speed table according to the number of tracks up to the target track. The DAC22, feed-forward
Feed forward signal from table 35 to DAC2
3 respectively. The output pulse of the track crossing detection 29 is converted into a speed by the speed detection circuit 30, and D
It is output to the differential amplifier 31 together with the target speed of the AC 22, and the differential amplifier 31 outputs a signal according to the difference between the two signals. The signal of this differential amplifier 31 is
It is a signal indicating the speed difference between the speed of the light beam focused on the recording medium 1 and the cross-track speed, that is, a speed error signal.

The output signal of the differential amplifier 31 is applied to the coil 12 through a phase compensating circuit 32 for compensating the phase of the tracking speed control system, a switch 25, an adding circuit 33 and a driving circuit 18. Therefore, the objective lens 8 is driven in accordance with the signal from the differential amplifier 31, and the speed of the light beam converged on the recording medium 1 is controlled so as to always match the target speed.

The feed forward signal is a DAC
It is added to the drive signal via the switch 23, the switch 26 and the adder circuit 33 in order to reduce the error of the tracking speed control system.

FIG. 2 shows the relationship between the time and the target speed signal at this time.
(A), Fig. 2 shows the relationship between time and feed forward signal.
(B). However, in the present embodiment, there is no disturbance factor such as the running resistance of the tracking actuator, and it is assumed that the tracking actuator is ideal.

Next, measurement of running resistance and sensitivity of the tracking actuator will be described. The search operation is performed between the predetermined two points in the same manner as the search for tracking. Control unit 20
Represents the drive signal output from the adder 33 at that time by the ADC 34
Monitor by. The relationship between the time and the drive signal at that time is shown in FIG. It is assumed that the drive voltage during the acceleration period (0 <t <t1) is Va, the drive voltage during the constant speed period (t1 <t <t2) is Vb, and the drive voltage during the acceleration period (t2 <t <t3) is Vc. .

In FIG. 2 (c), the table values are change points T0 to T1 to T2 to T3 instruction values [Va] [Vb] [-Vc] [0] 8 bits E0H 90H 30H 80H where T0 to T3 Is the value at the change point, and [V] is V
Indicates a digital value for indicating.

At this time, the driving sensitivity of the tracking actuator (including the driving circuit 18) is set to α (m / S2 /
V), the running resistance of the tracking actuator is f
b (N), mass of tracking actuator m (k
g), the equation of motion of the tracking actuator during the acceleration period is as follows.

MαVa = m (dv / dt) + mαVb (1) where the m (dv / dt) term on the right side is dv / dt = v0 / t1 during the acceleration period, and the next mαVb term is the resistance load force. Is. From the above, the drive sensitivity α and the resistance load force fb of the tracking actuator are given by the following equations.

Α = v0 / [t1 (Va-Vb)] (2) fb = mVbv0 / [t1 (Va-Vb)] (3) Also, not only one way but also round trip between two predetermined points. Alternatively, the results calculated from the forward and return routes may be averaged.

Next, the operation of correcting the traveling resistance and sensitivity of the tracking actuator will be described by taking a comparatively short movement as an example. FIG. 3A shows a target speed profile. This target speed profile has an acceleration period (0 <t <t10) on the left side and a deceleration period (t10 <t <2t10) on the right side around t10. The feed-forward table 35 before correction is shown by the dotted line in FIG. 3B and is made up of an acceleration period V1 and a deceleration period -V1.

Then, correction is made based on the driving sensitivity α of the tracking actuator and the resistance load force fb obtained by the measurement. The equation of motion of the tracking actuator during the acceleration period is as follows.

MαVx = m (dv / dt) + mαVb (4) Since the m (dv / dt) term on the right side is dv / dt = t10 / t10, the acceleration instruction Vx is as follows.

Vx = v10 / (t10 · α) + Vb (5) The equation of motion of the tracking actuator during the deceleration period is as follows. mαVy = m (dv / dt) + mαVb (6) Since the m (dv / dt) term on the right side is dv / dt = v10 / t10, the acceleration instruction Vy is as follows.

Vy = −v10 / (t10 · α) + Vb (7) The Vx and Vy desired to be obtained as described above are stored in the corrected feed forward table.

FIG. 5 shows an example of the feed forward table 35. This feed-forward table shows the correction voltage f based on the relationship between the moving distance L and the time t required for the movement, and the correction voltage f is obtained by the above-mentioned formula.

According to the first embodiment as described above, when the running resistance and sensitivity of the tracking actuator are measured, the tracking actuator is moved by applying the speed servo, so that the actuator runs away due to disturbance during measurement or the like. It is possible to measure in a short time without doing anything.

Further, by reciprocating between two predetermined points and averaging the measurement results, accurate running resistance and sensitivity can be obtained without being affected by the inclination of the device. Since the error component of the feed / forward drive signal is corrected based on the measurement result, a stable track search operation can be performed without being affected by variations in running resistance and sensitivity and aging.
Here, the error component of the feed-forward drive signal refers to an error caused by a temporal change or variation in mechanical sensitivity of a drive mechanism for moving to a track, running load, or the like.

Next, a second embodiment according to the present invention will be described. The configuration of this embodiment is the same as that of the above-described first embodiment, but the operation is different, and the features thereof will be described.

In the above-described first embodiment, the feed forward table 35 is constant regardless of the track search direction, that is, from the inner circumference to the outer circumference of the disk or from the outer circumference to the inner circumference of the disk (however, the polarity is opposite. )Met.
In the second embodiment, the feed-forward table 35 has two types depending on the track search direction.

Next, the outline of the correction operation will be described. The search operation is performed between the predetermined two points in the same manner as the search for tracking. For example, first, the process is performed from the inner circumference to the outer circumference of the disc. Similar to the first embodiment, the running resistance and sensitivity of the tracking actuator are measured from the feed-forward signal at that time, and the feed-forward table from the inner circumference to the outer circumference of the disk is corrected based on the result. Then, the feed-forward table is corrected from the outer circumference to the inner circumference of the disk in the same manner as described above from the outer circumference of the disk to the inner circumference.

Next, the measurement of the running resistance and sensitivity of the tracking actuator when the search control device of the present embodiment has a high outer peripheral side and a low inner peripheral side will be described. Similar to the tracking search, the search operation is performed back and forth between predetermined two points. First, the measurement is performed from the inner circumference to the outer circumference of the disc. The target velocity profile is shown in FIG. The control unit 20 shown in FIG. 1 monitors the drive signal of the output of the adder 33 at that time by the ADC 34. The relationship between the time and the drive signal at that time is shown in FIG. The drive voltage in the acceleration period (0 <t <t1) is Vaf, the drive voltage in the constant speed period (t1 <t <t2) is Vbf, the acceleration period (t2
It is assumed that the driving voltage <t <t3) is Vcf.

At this time, the driving sensitivity of the tracking actuator (including the driving circuit 18) is set to α (m / S2 /
V), the running resistance of the tracking actuator is f
b (N), mass of tracking actuator m (k
g), the equation of motion of the tracking actuator during the acceleration period is as follows.

MαVaf = m (dv / dt) + mαVbf (8) Here, the m (dv / dt) term on the right side is dv / dt = v0 / t1 during the acceleration period, and the mαVbf term is the resistance load force. . From the above, the driving sensitivity α and the resistance load force fbf of the tracking actuator are given by the following equations.

Α = v0 / [t1 · (Vaf−Vbf)] (9) fbf = mVbfv0 / [t1 · (Vaf−Vbf)] (10) Next, measurement from the inner circumference to the outer circumference of the disk is performed. . The control unit 20 outputs the drive signal of the output of the adder 33 at that time as A
Monitored by DC34. The relationship between the time and the drive signal at that time is shown in FIG. 4 (c). Acceleration period (0 <t <t1
), The drive voltage during the constant speed period (t1 <t2) is Vbr, and the drive voltage during the acceleration period (t2 <t <t3) is Vcr. The driving sensitivity α and the resistance load force fbr of the tracking actuator are given by the following equations as in the above.

Α = v0 / [t1 (Var-Vbr)] (11) fbf = mVbrv0 / [t1 (Var-Vbr)] (12) where the search control device is high on the outer peripheral side of the disk Since the circumferential side is inclined in the lower direction, the tracking actuator is easy to move from the outer circumference to the inner circumference, and difficult to move in the opposite direction. Therefore, Vaf> Var and Vbf> Vbr.

The correction of the running resistance and sensitivity of the tracking actuator is stored in the feed-forward table 35 according to the search direction as in the first embodiment.

As described above, since the search control device of the second embodiment measures the running resistance and sensitivity of the tracking actuator by moving the tracking actuator by applying the speed servo, It is possible to measure in a short time without the actuator going out of control due to disturbance or the like.

Further, by reciprocating between two predetermined points and determining two types of running resistance and sensitivity depending on the direction, the current actual operating characteristics including disturbance such as inclination of the device can be measured.

Since the feed-forward signal is corrected based on the above measurement result, stable track search operation can be performed regardless of variations in running resistance and sensitivity, influence of aging, and track search direction.

[0047]

As described above in detail, according to the present invention, when the traveling load of the moving means is measured, the traveling load can be measured stably and in a short time regardless of variations in the traveling load and the driving sensitivity of the moving means. It is possible to provide a search control device that can do this.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration example of a search control device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between time and a target speed signal, a relationship between time and a feed-forward signal, and a relationship between time and a drive signal in the first embodiment.

FIG. 3 is a diagram showing a relationship between time and a target speed signal and a relationship between time and a feed forward signal in the second embodiment.

FIG. 4 is a diagram for explaining the measurement of running resistance and sensitivity of the tracking actuator when the outer peripheral side of the disk is high and the inner peripheral side is low.

FIG. 5 is a diagram showing an example of a feed forward table.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Recording medium, 2 ... Motor, 3 ... Light source, 4 ... Collimator lens, 5 ... Polarization beam splitter, 6 ... Quarter wave plate, 7 ... Total reflection mirror, 8 ... Objective lens, 9 ... Photodetector, 1
0 ... Leaf spring, 11 ... Tracking actuator, 12
... coil, 13, 14 ... amplifier, 15, 31 ... differential amplifier, 16, 32 ... phase compensation circuit, 17, 25, 26 ... switch, 18 ... drive circuit, 19, 33 ... addition circuit, 20
... Control unit, 21 ... Address input device, 22, 23 ... DAC,
24, 27, 28 ... Line, 29 ... Track crossing detector, 30 ... Speed detection circuit, 35 ... Feed forward table, 36 ... Speed profile table.

Claims (3)

[Claims] 1. A reproducing means for reading and reproducing an information signal recorded on a recording medium, and a reading portion of the reproducing means for moving a track on the recording medium in a substantially width direction of the track to a desired track. In a search control device for moving a track desired to be read by carrying out transfer control by a speed servo that adds a feed forward signal to a drive signal of the moving means, to a track desired to be read. The movement of is based on a drive signal for driving the moving means to which the speed servo is applied so as to have a predetermined speed profile for accelerating to a predetermined target value and decelerating to stop at the track position. Correction means for correcting the feedforward signal for performing the speed servo so that the error component of the feedforward signal is minimized. Said moving means is driven before the start, based on the correction value determined by said correction means during the driving, the search control unit and correcting the movement of subsequent said moving means. 2. The correcting means moves the reading portion by the moving means with an acceleration / deceleration speed characteristic having a constant speed period between any two points on a recording medium, and the moving means moves the reading portion. 2. The search control device according to claim 1, wherein a correction value based on driving sensitivity and / or traveling load is obtained and correction is performed so that an error component of the feed-forward signal is minimized. 3. The feedforward in which the correction means determines a plurality of feedforward signals in which the drive voltage of the moving means is corrected based on the relationship between the moving distance and moving time of the reading portion by the moving means. A table and used when moving the reading part by the moving means according to the moving distance to the track desired to be read out,
A speed profile table having a plurality of speed profiles in which an acceleration period, a deceleration period, and a constant speed period are defined;
The search control device according to claim 2, further comprising: