JPH0325729A - Track jump control circuit for optical disk - Google Patents

Abstract

PURPOSE:To always perform one track jump with high accuracy by absorbing the dispersion of an actuator even when the jump is performed at high speed by adding the differential output of a tracking error when performing the jump as a braking signal. CONSTITUTION:The contact c of a selection switch 16 connected to the contact a in an ordinary operation is selected when a jump command signal is inputted from a one-track controller 17, and a kick pulse Pk with polarity to drive a tracking actuator 11 to a targeted track side is supplied via a polarity inversion circuit 15. The actuator 11 is accelerated to the inner side of a disk, and the output of the tracking error in jumping is sent to a comparator 14 via a differentiation circuit 12, and a zero cross point is detected, and is sent to the controller 17, then, the contact b is selected. And a pulse with the polarity opposite to that of the Pk is sent to the actuator 11 via a polarity inversion circuit 15, and is decelerated, and next, when the contact is returned to the contact a, a tracking-on state is immediately generated, then, jump access is completed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a track jump control circuit that is performed when reading information recorded on an optical disc, and in particular, the present invention relates to a track jump control circuit that is performed when reading information recorded on an optical disc. This paper relates to a track jump control circuit for optical discs that is suitable for realizing a still state. [Summary of the Invention] The optical disc track jance control circuit of the present invention comprises:
When an optical disc is operated by a tracking servo, a differential output of a tracking error signal during a jump is applied as a braking signal to an actuator performing a jump operation by supplying a kick pulse to speed up the track jump. l It is designed to increase the accuracy of track jumps. ? BACKGROUND ART A recordable optical disc l on which information can be recorded or reproduced has a spiral track 2 formed by groups or sampling bits at 119 as shown in FIG. This spiral track 2 is further divided into n sections in the circumferential direction, and an address area 3 is placed at the beginning of the track 2.
It is divided into sectors 4,,4■...4,, which are equipped with. And normally this sector 4+. 4a・
...While reading the address added to 4n, recording and reproducing data is performed sequentially from the inner circumferential side to the outer circumferential side, but a still operation is performed in which only the same track number is read out. In this case, a tracking actuator (not shown) that irradiates the laser beam onto the optical disc l jumps one track, and for example, as shown by arrow J, the laser beam is returned to the inner circumferential side by one track for each rotation of the optical disc 1. , scanning is performed in which the original track is irradiated with a laser beam, that is, a one-track jump is performed.

When performing this one-track jump, as shown in FIG. 6(a), at time t1, a kick pulse (negative polarity) PK is input to the tracking servo circuit to move the actuator in the inner circumferential direction, and at the same time A well-known method is to introduce the brake pulse P8 in the second half and access the inner track of the l track at time t2. [Problem to be solved by the invention] +. ;1 This jump control system works by setting the supply time and level of kick pulse P8 and brake pulse PB appropriately, and a traverse signal as shown in FIG. , ~t2], but if you try to increase the speed so that one track jump ends within l sector of the optical disc as shown in Fig. 5, the tracking actuator variation (especially , coulomb friction and stick friction of the tracking actuator), when the tracking actuator moves quickly, it overshoots as shown in FIG. 6(c), and as a result, the track access time t. becomes longer.

Also, if the tracking actuator is not moving properly,
As shown in FIG. 6(d), the jump time j l"'=
There was a problem that j2 became longer and the speed of the track jump decreased.

Therefore, as shown in FIG. 7, at time t3 in the second half after the acceleration operation by the kick pulse PK ends, the tracking error signal of the opposite polarity obtained during the jump is supplied as a brake signal to the tracking actuator, and the target 1
A method is known in which a position servo is added corresponding to the distance to the track in front of the track, but in this method, when the tracking actuator is made to jump one track within one sector, the tracking actuator still The problem was that it was not possible to absorb the effects of variation. [Means for Solving the Problems] The present invention has been made in view of these problems.
The tracking actuator is equipped with means for supplying a kick pulse to accelerate the tracking actuator based on a track jump command, and a braking signal generating means for outputting a differential output of a tracking error signal outputted at least during a jump as a braking signal. By supplying a braking signal having a polarity opposite to that of the kick pulse to the tracking actuator during movement, the track one track in front is accessed.

[Effect] i. l When the tracking error outputted while the hooking actuator is moving is differentiated, relative moving speed information between the optical disc and the tracking actuator is detected, so this moving speed information is fed back after the tracking actuator is accelerated. By doing so, it is possible to perform braking that corresponds to changes in jump speed based on variations in the tracking actuator. [Embodiment] FIG. 1 shows a block diagram of the track jump control circuit of the present invention, where 10 is a phase compensation circuit that compensates for the phase of tracking error Et in normal tracking servo operation, and 1l is a laser beam. This is a tracking actuator that illuminates the tracks of an optical disc. Reference numeral 12 indicates a differentiation circuit that differentiates the tracking error Et, and the output of this differentiation circuit 12 is supplied to a polarity inversion circuit 13.

S, is a signal voltage corresponding to the level of the above-mentioned kick pulse P8, and this signal voltage S is also supplied to the polarity inverting circuit 15.

These outputs are output from each of the selection switches 16 a, b.
It is connected to the C contact and is configured to be switched at an appropriate time by a control signal output from the 1-track controller 17. Note that 14 indicates a converter that detects the zero-crossing point of the braking signal output from the differentiating circuit 12 (E. and V 466 indicate waveform diagrams of other embodiments to be described later). Hereinafter, the operation of the above embodiment will be explained with reference to the waveform diagram of FIG. 2.

During normal recording and playback, the a contact of the selection switch l6 is selected, and the tracking servo state is set to track the track of the optical disc. (1) A jump command signal (F
/R) is supplied, the C contact of the switch 16 is selected at time t1, and the target track (hereinafter referred to as 1 on the inner circumference side) is selected.
A kick pulse P9 having a polarity that drives the tracking actuator l1 to the (explaining the track return pause operation) side is generated by supplying the signal voltage SJ via the polarity inverting circuit l5.

Therefore, the tracking actuator 1l is accelerated toward the inner circumferential side of the optical disc between t1 and t2 of the track jump signal VJa, and when moving to an adjacent track, the tracking actuator 1l is
As shown in the figure, the almost sinusoidal tracking error E
t is output.

Since the tracking error Et (traverse signal) during the jump is supplied to the differentiator circuit l2, its differential output Etl changes as shown in FIG.

The converter 14 operates at a zero cross point t2 of this differential output.
When detected, a signal is supplied to the 1-track controller 17 to control the switch 16 to select the b contact. Therefore, from this time point t2, the kick pulse P. The differential output E. The signal shown in the shaded area is supplied to the tracking actuator l1 via the polarity inversion circuit 13. Since this signal is switched to have the opposite polarity to the kick pulse PK, it becomes a control voltage for the tracking actuator 11 and causes a deceleration effect between time points j z and j s. Next, at time t3, the a contact of the switch 16 is selected by the l track controller 17, and the state returns to the tracking servo state, but at this point, the moving speed of the tracking actuator 1l is sufficient to achieve the tracking state. Therefore, at time t4, the tracking ability state immediately becomes achievable, and the one-track jump access ends.

The signal waveform in FIG. 3 shows a case where the actuator moves quickly.

As can be understood from the signal waveforms in FIGS. 2 and 3, the level S8 of the differential output Etd of the differentiating circuit 12 increases in proportion to the moving speed of the tracking actuator 11 (angular velocity ω of the tracking error Et). , when the actuator moves poorly, the braking voltage decreases,
On the other hand, when the actuator moves quickly, the differential output Etd becomes a large amplitude signal (■・ωCO
Sωt), which is supplied as a braking signal.

Therefore, the kick pulse P and the differential output E ta
By setting servo circuit to a large value that does not saturate the servo circuit, the appropriate speed servo can be applied even if there is some variation in the actuator, increasing the speed of one track jump and accurately jumping adjacent tracks. You will be able to perform track jumps to access the . The above embodiments have been explained regarding pause or still operation, but when the output signals of the polarity inversion circuits 13 and 15 are inverted,
It goes without saying that a one-track jump can be made to an adjacent track on the outer circumference. Since FIG. 4 shows another embodiment of the present invention, the same functions as those in FIG. 1 are given the same reference numerals.

In this embodiment, the differentiating circuit l2 is a two-stage differentiator 12.
A. It consists of 12B. Therefore, in this embodiment, the twice differentiated output E, of the differentiator circuit 12. 6 is a tracking actuator l as shown in FIGS. 2 and 3.
1 acceleration and 13 reports, it is possible to expand the speed change of the tracking actuator to a larger dynamic range and output it.

In this example, the signal waveforms (Eta,) and (VJd
As shown in d), at time t6 when the humpator detects the second zero cross point, the one-track controller 17 outputs a signal to select the b contact of switch l6, and at time t7 the tracking servo is added. Make it.

The area that becomes the braking voltage is the shaded area of the second differential output E tdd, and since the signal level in this area is proportional to the square of the actuator speed information, a rapid deceleration effect occurs in the latter half of the jump. .

Therefore, the time for applying the kick pulse P8 is lengthened, thereby making it possible to further increase the speed of the tracking actuator.

In the above embodiment, a differentiating circuit 12 is newly added, a tracking error signal during a jump is supplied, and the output is used to apply braking, but the output characteristics of the phase compensation circuit 10 are A phase shift occurs from a certain frequency, and when a traverse signal during a jump is input, a differentiated output may be generated.

Therefore, as shown by the dotted line in FIG.
It is also possible to extract the differential output component within O and use it for the braking signal. Also, the differential output E td or E tll which becomes the braking signal
It is also possible to add the conventional position information of the tracking actuator to + as a braking signal, and further add position servo to the speed servo of l track jump.

[Effects of the Invention] As explained above, the track jump control circuit for an optical disc of the present invention accelerates the actuator to perform a track jump in which an adjacent track is accessed. Since the differential output of the tracking error is added, it is possible to absorb actuator variations when performing track jumps at high speed, and it is possible to always perform highly accurate l-track jumps.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a track jump control circuit according to the present invention, FIGS. 2 and 3 are signal waveform diagrams of various parts during a track jump, and FIG. 4 is a track jump control circuit showing another embodiment of the present invention. FIG. 5 is a plan view showing an example of an optical disc, and FIG. 6 is a block diagram of the optical disc. FIG. 7 shows a conventional track jump signal waveform diagram. In the figure, IO is a phase compensation circuit, l1 is an actuator, l
2 is a differentiating circuit, 14 is a combiner brake, 16 is a selection switch, and 17 is an l-track controller.

Claims (3)

[Claims] (1) An actuator whose tracking is controlled based on a tracking error signal of an optical disk, a kick pulse generating means for accelerating the actuator to perform a track jump, and a means for applying braking to the actuator during the track jump. An optical disc comprising: a braking signal generating means, wherein the braking signal generating means is configured to differentiate a tracking error signal during a jump and output a braking signal having a polarity opposite to that of the kick pulse. Track jump control circuit. (2) Tracking of the optical disc according to claim (1), wherein the braking signal is obtained by differentiating the tracking error signal during the jump twice and has a polarity opposite to that of the kick pulse. Jump control circuit. (3) The track jump control circuit for an optical disc according to claim (1), wherein a signal obtained by inverting the tracking error signal is added to the braking signal.