JPS61276134A - Track jump controller - Google Patents

Abstract

PURPOSE:To attain an accurate and quick track jump action by switching the acceleration pulse signal to the deceleration signal based on the result of comparison between a tracking error signal and the divided peak value of said error signal. CONSTITUTION:The tracking error detecting signal detected by a tracking error detecting circuit 6 is applied to comparators 14 and 15 and the positive and negative peak holding circuits 10 and 11 respectively. The circuits 10 and 11 store the positive and negative peak values of the tracking error signal respectively during a track jump with an indication given from a controller 17. While the circuits 12 and 13 divide the positive and negative peak values respectively and these divided values are compared with the tracking error signal by the comparators 14 and 15 respectively. A track jump pulse generating circuit 16 performs the rough retrieval with an indication of the controller 17. Then the acceleration pulse is switched to the deceleration pulse by the output of the comparator 14 or 15. Thus a track jump pulse including positive and negative pulses is delivered.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a track jump control device for a recording/reproducing apparatus for recording and/or reproducing an optical disk or a magneto-optical disk (hereinafter simply referred to as an optical disk).

(Background of the Invention) A disc-shaped record carrier of an optical disc recording/playback device includes:
The grooves or pit rows for recording and reproducing signals and the rows of recorded signals have a concentric or spiral shape (hereinafter referred to as "tra").
Track jumping, which is currently performed using an optical dump, involves applying a jump pulse signal to an actuator that causes a light beam to follow a track, thereby moving the light beam to the adjacent trunk. This technique has already been proposed in Japanese Patent Laid-Open No. 52-26802 and is well known.

Figure 2 shows an example of a track jump.
The track jump is performed by using a jump pulse signal, first adding an acceleration pulse signal Pa of a constant amplitude, and then adding a deceleration pulse signal pb of opposite polarity at a time interval for the same time as the acceleration pulse signal Pa. FIG. 2 (bl indicates a tracking error signal at the time of track jump).

The tracking error signal ST is a predetermined reference signal 3.
This is when the two match. However, the shape of the tracks on the record carrier varies; for example, in the case of grooves, the etched portions often have an irregular shape. In this case, the amplitude of the tracking error signal at the time of track jump may decrease. Furthermore, since it crosses the track groove, focus control is affected to some extent, making the amplitude of the tracking error signal smaller. Figure 2 1
In b), the tracking error signal S°A whose amplitude has decreased is shown by a dotted line. Because the amplitude of the tracking error signal has decreased in this way, the timing of switching from the acceleration pulse signal Pa to the deceleration pulse signal has changed from t to t in FIG. This has the disadvantage that the jump pulse signal becomes as shown by the dotted line in Figure 2 +8), and the rack jump (Pa', Pb')) is not performed accurately.

(Object of the Invention) The present invention solves these drawbacks and always accurately detects the timing of switching the jump pulse signal for track jump, that is, the timing of switching from the acceleration pulse signal to the deceleration pulse signal, regardless of the amplitude of the tracking error signal. The object of the present invention is to obtain a track jump control device capable of always accurate and quick track jumps.

(Embodiment) FIG. 1 shows a block diagram of an embodiment of the present invention. In FIG. 1, l is a record carrier, and tracks are formed by grooves or signal trains. 2 is a galvanometer. laser 4
The light beam generated at S! passes through the galvanometer 2.
It is reflected by the carrier 1, and the reflected beam 18 is split by the beam splinter 3 and reaches the photosensor 5. In the above 2 to 5, the reflected beam 18 is converted into an electric signal by the photosensor 5 mounted on the middle ridge and forming the head H, and the tracking error signal detection circuit 6 detects the tracking error signal. The tracking error signal is used for tracking control to cause the light beam 18 to follow the track of the record carrier. 21 is a driving means for driving the head H;
20 is controlled by the controller 17 to connect the switch 9 to A when tracing the trunk, which controls the driving means, and is controlled by the controller 17 to connect the switch 9 to A, and is connected to the galvano mirror via the tracking control circuit 7, the switch A1 of the switch 9, and the driver 8 according to the tracking error signal S1. -2 is moved and tracking control 1 (track tracing) is performed.

10 is a positive peak hold circuit, and 11 is a negative peak hold circuit, which stores the peak value of the tracking error signal at the time of track jump according to instructions from the controller 17. 12.13 is a voltage dividing circuit, and peak hold circuit 10. ．． 0 voltage dividing circuit 1 which divides the peak value obtained in step 11 into a predetermined ratio.
2. The peak value divided in 13 is the comparator circuit 1.
4.15, it is compared with the tracking error signal.

Reference numeral 16 denotes a track jump pulse generation circuit, which switches an acceleration pulse signal to a deceleration pulse signal by the output of either the comparator circuit 14 or the comparator circuit 15, which is selectively selected by the controller 11 from the controller 17. It controls and outputs track jump pulses consisting of positive and negative pulses.

The time during which the deceleration pulse signal is output is also determined by the track jump pulse generation circuit 16.

Here, the positive peak hold circuit 10. The voltage dividing circuit 12, the voltage dividing circuit 11, the voltage dividing circuit 13, and the comparator circuit 15 are as follows:
This is a circuit system 32 for track jumping toward the inner circumferential side.

FIG. 3 shows a timing chart when the track jumps to the outer circumference side. This is a voltage-divided peak value signal obtained by manually inputting the signal in FIG. 3 (C1 is in FIG. 3) to the voltage dividing circuit 12. Figure 3 (el
is a jump pulse signal output from the track jump pulse generation circuit, and track jump starts at time t1. The signal obtained by comparing the tracking error signal +al in FIG. 3 with the divided peak value signal tel in FIG. 3 by the comparator circuit 14 is +dl in FIG. Figure 3 (Track jump ends at time 0 [, where the jump pulse signal fails to change from acceleration pulse to deceleration pulse at timing t! from dl, and time t is
It is determined that L3 h=kg L+. The timing of the end of the track jump is disclosed in detail in JP-A-52-26802 or JP-A-52-50098.
It will not be detailed here.

Next, the third case where the amplitude of the tracking error signal decreases is
When the tracking error signal decreases as shown by the dotted line St in FIG.
The cl signal is also shown by a dotted line. However, since the two input signals to the comparator circuit 14 are decreasing at the same rate, the timing at which the output of the comparator circuit 14, that is, the acceleration pulse signal is switched to the deceleration pulse signal, is the third one.
As is clear from the figure (d), there is no change, that is, the switching time t8 of the jump pulse signal does not change, so the positive -1
Also, you can perform quick track jumps.

(Effects of the Invention) As described above, according to the present invention, the amplitude of the tracking error signal due to variations in the formation of the trunk groove of an optical disc or the formation of a signal train, or the distortion of the focus control,
Since the timing of a track jump, that is, the timing of switching from an acceleration pulse signal to a deceleration pulse signal, can be detected without being affected by changes, the track jump can be performed accurately and the time required to search for the desired trunk can be shortened. . Furthermore, the accuracy of track formation on the optical disc may be low, making it easier to manufacture the optical disc.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an apparatus according to the present invention, FIG. 2 is a timing diagram of a conventional track jump, and FIG. 3 is a timing diagram of a track jump according to the present invention. (Explanation of symbols of main parts)

Claims (1)

[Scope of Claims] A track jump pulse generation circuit that outputs a track jump pulse consisting of continuous positive and negative pulses having substantially the same time width; A tracking error signal detection circuit that outputs a tracking error signal; A comparator; a peak hold circuit that holds the peak value of the error signal; and a voltage divider circuit that divides the output voltage of the peak hold circuit; the output of the voltage divider circuit is connected to the reference input terminal of the comparator, and the tracking error is A track jump control device, characterized in that a signal is connected to an input terminal of the comparator, and switching between positive and negative of the continuous pulse is controlled by the output of the comparator.