JPH0419832A - Velocity control system for optical disk device - Google Patents

Abstract

PURPOSE:To drive a positioner at a high level of acceleration and to attain a high speed access by applying the feedback to a positioner actuator so as to set the difference at 0 between a corrected light beam velocity signal and a reference velocity signal. CONSTITUTION:A relative velocity generating means 22 generates a relative velocity between a positioner actuator 27 and a condensing means 3 as a velocity correction signal based on the position error signal between the actuator 27 and the means 3. As a correction velocity signal is obtained by adding the velocity correction signal to a light beam velocity signal detected out of a tracking position error signal. Then the velocity feedback control is carried out during an access action by means of the correction velocity signal. Thus a light beam 2 is stably moved up to a target track when an access is given to an optical disk device at a high level of acceleration.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to an optical disc device that performs recording and reproduction using a light beam. Regarding control method.

[Prior Art] When performing track access on an optical disk, a method of detecting the relative speed of the light beam and the optical disk and moving the light beam by controlling the speed is disclosed in Japanese Patent Application Laid-Open No. 59-207439, ``Beam Access in Optical Disk Devices''. Apparatus”.

FIG. 3 shows a block diagram of a configuration in which a speed control system for an optical disk device for access operations is realized using this conventional technique. In this prior art, a spring-supported tracking actuator 9 includes a positioner 4 and a focusing means 3.
A sensor 5 is provided to detect the positional deviation of the light collecting means 3 as a positional deviation signal 6, and the sensor 5 detects the displacement of the light collecting means 3 due to the acceleration during access, and a filter 7 is provided so that the displacement of the light collecting means 3 becomes O. A tracking actuator 9 is driven by the positional deviation signal 6 via the amplifying means 8.

A track crossing pulse 14 is generated by the track crossing detecting means 13 from the tracking position error signal 12 detected by the tracking position error detecting means 11 in the optical head 10 during the access operation.
The speed generating means 20 detects the relative speed between the light beam 2 and the optical disk 1 as a light beam speed signal 21, and also detects the number of seek tracks 16 preset in the counter 15 by an external controller not shown in the drawings.
The number of remaining seek tracks 17 is determined by decrementing the number 17 in accordance with the track crossing pulse 14, and the reference speed generating means 18 generates a reference speed signal 19 from this number 17 of remaining seek tracks. At this time, the reference speed signal 19
The difference between the speed error signal 25 and the light beam speed signal 21 is used as a speed error signal 25, and the positioner actuator 27 is driven via the amplifying means 26 so that the speed error signal 25 becomes 0, so that the speed of the light beam 2 follows the reference speed. The speed of the light beam 2 is controlled to move between the tracks.

(Problems to be Solved by the Invention) In the prior art, the loop gain during the speed control system using the positioner actuator is ω1, and the loop gain during the position control system using the tracking actuator to position the light focusing means with respect to the positioner is ω2. Open loop gain ω1. When ω2 is included in the transfer function of each actuator, the block diagram of FIG. 3 can be expressed as shown in FIG. 4. The reference velocity signal 19 output from the reference velocity generating means 18 in FIG. 3 is subtracted from the light beam velocity signal 21 in FIG. 4 to generate a velocity error signal 25, and the equivalent block 30 of the positioner actuator.
31 (transfer function ω, /s, 1/s). The positional deviation between the positioner 4 and the condensing means 3 is detected by the sensor 5 in FIG. 3, and the positional deviation signal 6 in FIG.
Equivalent filter 32 (transfer function (3s+ωz) /
(s +3ω2)) is input to the equivalent trunking actuator 33 (transfer function ω22/S2).

Speed detection during access operation is performed by optically transmitting a track crossing pulse 1 based on a tracking position error signal 12 detected by a tracking position error detection means 11 in the door 10.
4, and the relative speed between the light beam 2 and the optical disk 1 is detected by the speed detection means 20 as a speed signal 21 of the light beam. FIG. 4 shows an equivalent block from this optical head to the speed detection means 34 (transfer function S
).

In order to achieve high-speed access, it is necessary to set a large acceleration during access operation, and in order to achieve stable access with large acceleration, the speed band of the speed control system, that is, the open loop gain ω1 of the speed control system It is necessary to take a large value. However, in the conventional speed control system, as shown in Figure 4, the speed control system includes a position control system using a tracking actuator to suppress positional deviation between the light focusing means and the positioner. The open loop gain ω2 of the position control system to reduce the positional deviation of the positioner to 0 must be a sufficiently large value with respect to the loop gain ω1 of the speed control system, and the relationship ω2 〉ω1(1) must be satisfied. There is.

In an actual device, the loop gain ω2 in the position control system using the tracking actuator is limited in magnitude by the mechanical resonance characteristics of the tracking actuator.

Consider the case where ω1 is increased in order to increase the speed band. ω and ω2 are almost equal, or ω is smaller than ω1
When 2 is small, that is, when ω2 minus ω1(2), the velocity becomes oscillatory or diverges. For this reason, it has been shown that stable control cannot be achieved when there is a relationship expressed by equation (2).

This causes a problem that the speed control band during the access operation is limited by ω2, making it difficult to realize high-speed access with large acceleration.

An object of the present invention is to provide a speed control method for an optical disk device that enables stable movement of a light beam to a target track even when performing high-speed access using large acceleration in the access operation of the optical disk device. There is a particular thing.

[Means for Solving the Problems] The present invention provides a tracking actuator that moves a light beam in a minute range on an optical disk by moving a light focusing means in a tracking direction, and a tracking actuator that moves a light beam in a minute range on an optical disk by moving a light focusing means in a tracking direction, and a tracking actuator that moves a light beam together with the tracking actuator for recording on an optical disk. The tracking direction of the light beam is controlled by two actuators: a positioner actuator that moves the light beam on the optical disk by moving over the entire range of the playback area, and the speed of the light beam is detected during the access operation to reach the target track. In a speed control method for an optical disk device that moves a light beam by speed control, a sensor detects a positional deviation between a positioner actuator and a light condensing means as a positional deviation signal, and a filter and an amplification means are used to set this positional deviation signal to O. The tracking actuator is driven by the positional error signal detected by the optical head, and the track crossing detection means generates a track crossing pulse from the tracking position error signal detected by the optical head. The number of moving tracks of the light beam is decremented by a counter in accordance with the track cross pulse to generate the number of remaining seek tracks, and the reference speed generating means generates a reference speed signal corresponding to the number of remaining seek tracks. A speed detection means detects the relative speed of the light beam and the optical disk from the ranking position error signal to generate a light beam speed signal, and based on the positional deviation signal, the relative speed generation means speed-corrects the relative speed of the positioner actuator and the light focusing means. The difference between the corrected light beam speed signal generated as a signal and the addition of the light beam speed signal and the speed correction signal and the reference speed signal is used as a speed error signal, and the positioner actuator is set so that this speed error signal becomes 0. It is characterized in that the velocity of the light beam is made to follow the reference velocity signal by applying a feedbank to the reference velocity signal.

(Operation) In the speed control method of the optical disk device according to the present invention, the
The relative speed of the positioner actuator and the light focusing means is generated as a speed correction signal by the relative speed generating means, and the access operation is performed using the correction speed signal obtained by adding the light beam speed signal detected from the tracking position error signal and the speed correction signal. Speed feedback control is performed inside the vehicle.

An equivalent block diagram representing the speed control system according to the present invention using a transfer function is shown in FIG. 2(a). In Figure 2(a),
Block 30.3 shows the equivalent program from input to velocity and velocity to position of the positioner actuator, respectively.
1 (transfer function ω, / s , 1 / s ), the equivalent block of the filter is converted into the equivalent filter 32 (transfer function (
3s±ω+)/(s+3ω1)), the equivalent blocks from the input of the tracking actuator to the velocity and from the velocity to the position are respectively defined as blocks 36.37 (transfer functions ω2”/S, 1/S), and the positioner position is calculated as follows: , the velocity is P, ,V, respectively, the position and velocity of the light focusing means are P, ,Vo, and from the positional deviation signal 6 between the positioner and the focusing means, and the positional deviation signal 6, the equivalent block 35 of the relative velocity generating means is generated. Let the generated speed correction signals 23 be E, , V, respectively.Here, assuming that the equivalent block 35 has a differential element and the transfer function is G, then G,(s)=s (3). If the corrected speed signal 24 generated by adding the speed corrected signal 23 and the light beam speed signal 21 is 4, then Fig. 2 (
From a), V, =V. Ten ■.

;■. +5XEp =■. 15X (Pp Pa) =■. 10V, -V.

= V p (4). Considering that the corrected speed signal 24 is equal to the positioner speed ■ from the above results, Fig. 2(a)
The block diagram can be converted into the equivalent block diagram shown in FIG. 2(b). The speed control system shown in FIG. 2(b) is configured to make the reference speed signal 19 follow the positioner speed 2, and the transfer function Gv from the reference speed to the positioner speed is S+ω1. , a stable speed control system without divergence can be realized.

In actual equipment, it is difficult to realize the differential element shown in equation (3), and cd= (6)S+ω
8 is used, but if ω8 is sufficiently large compared to ω1 in speed control, that is, ω1(ωX(7)), then equation (3) for the speed control system is used. The same effect as using a differential element can be obtained.Actually, ω8 is ω
A sufficient effect can be obtained if the ratio is three times or more than 1.

(Example) Next, a speed control method for an optical disk device according to the present invention will be explained with reference to the drawings. Fig. 1 is a block diagram showing the configuration of an example of a control device realizing the speed control method for an optical disk according to the present invention. .

In FIG. 1, a position 1 in the tracking direction of a focusing means 3 for focusing a light beam 2 onto an optical disk 1 and a positioner 4 is shown.
The deviation is detected by the sensor 5 as a positional deviation signal 6, which is applied to the tracking actuator 9 via the filter 7 and the amplification means 8, and the position is controlled so that the positional deviation between the light collecting means 3 and the positioner 4 becomes 0. There is.

In the optical hand 10, the tracking position error detection means 1
1 detects a tracking position error signal 12 that changes periodically each time the light beam 2 crosses an information track on the optical disk 1, and a track crossing detection means 13 detects the tracking position error signal 12 that changes periodically each time the light beam 2 crosses an information track on the optical disk 1. One track-crossing pulse 14 is generated each time the beam 2 crosses the track.

At the start of the access operation, an external control device (not shown in the drawings) sets the number of seek tracks (16) between the track where the light beam 2 is located and the target track for recording/reproducing to the counter 15. The value of the counter 15 is decremented by the crossing pulse 14.

In this way, from the counter 15 during the access operation,
The number of remaining seek tracks (17) for moving the light beam to the target track is output.

The reference speed generating means 18 generates a reference speed signal 19 according to the number of remaining seek tracks. Here, the number of track crossing pulses 14 within a certain period of time is proportional to the number of tracks that the light beam passes through in a certain period of time, and considering that the track pitch of the optical disc 1 is approximately equal, The number of track-crossing pulses 14 in the track-crossing pulse 14, ie the frequency of the track-crossing pulses 14, is proportional to the speed of the light beam 2.

Therefore, by converting the frequency/voltage of the track crossing pulse 14, the speed detection means 20 can be realized and the light beam speed signal 21 can be generated.

Here, a speed correction signal 23 is generated with respect to the positional deviation signal 6 of the positioner 4 and the light condensing means 3 described above using a relative speed generating means 22 which can be realized by a pseudo-differentiation circuit or the like. Furthermore, a corrected speed signal 24 is generated by adding the light beam speed signal 21 and the speed correction signal 23, and the difference between the reference speed signal 19 and the corrected speed signal 24 is output as a speed error signal 25 to the positioner actuator 27 via the amplifying means 26. In addition,
The entire positioner 4 is driven so that the speed error signal 25 becomes O.

By using the speed control system configured as shown in FIG.
A tracking actuator 9 for making the positional deviation between the light condensing means 3 and the positioner 4 zero in controlling the speed of the
A stable speed control system that is not affected by the characteristics of the feedback control system can be realized.

〔Effect of the invention〕

By using the speed control method for an optical disk device of the present invention, a stable, wide-band speed control system for access operations can be realized, and it becomes possible to drive the positioner with large acceleration and perform high-speed access.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an example of a control device that implements the speed control method of an optical disk device of the present invention. FIG. 2 is an equivalent block diagram when the block diagram shown in FIG. 1 is expressed using a transfer function. 3 is a block diagram for explaining the conventional speed control method, and FIG. 4 is a block diagram when the conventional method is expressed by an equivalent transfer function. 1... Optical disc 2... Light beam 5... Positional deviation detection means 9... Tracking actuator 13...
・Truck crossing detection means 18...Reference speed generation means 20...Light beam speed detection means 22...Relative speed generation means 27...Positioner actuator representative Patent attorney Iwa Sa Yoshiyuki

Claims (1)

[Claims] (1) A tracking actuator that moves a light beam in a minute range on an optical disk by moving a light focusing means in the tracking direction, and an optical disk that moves the light focusing means together with the tracking actuator over the entire recording and playback area of the optical disk. An optical disk device that controls the tracking direction of the light beam using two actuators, a positioner actuator that moves the upper light beam, and detects the speed of the light beam during the access operation to move the light beam to the target track with speed control. In this speed control method, a sensor detects the positional deviation between the positioner actuator and the light focusing means as a positional deviation signal, and the tracking actuator is driven by the positional deviation signal via a filter and amplification means so that this positional deviation signal becomes 0. At the same time, a track crossing pulse is generated by the track crossing detection means from the tracking position error signal detected by the optical head, and the number of tracks traveled by the light beam to the target track set in advance on the counter from the external control device is calculated as the track crossing pulse. A counter decrements according to the pulse to generate the number of remaining seek tracks, a reference velocity signal corresponding to the remaining number of seek tracks is generated by the reference velocity generating means, and the relative velocity between the optical beam and the optical disk is determined from the tracking position error signal. is detected by a speed detection means to generate a light beam speed signal, and from the positional deviation signal, the relative speed generation means generates the relative speed of the positioner actuator and the light focusing means as a speed correction signal, and the The difference between the corrected light beam speed signal obtained by adding the speed correction signal and the reference speed signal is used as a speed error signal, and the speed of the light beam is set as a reference by applying feedback to the positioner actuator so that this speed error signal becomes 0. A speed control method for an optical disk device that is characterized by following a speed signal.