JPS62183073A - Track jump device - Google Patents

Abstract

PURPOSE:To execute a stable and exact tracking jump whose setting is executed quickly, by executing an operation for setting a racking servo-loop to a closed loop, in a state that a servo lead-in can be executed stably and quickly. CONSTITUTION:When a tracking jump is ended, a tracking error signal (a) is supplied to a window comparator 5 from a tracking error signal generating circuit 1, and it is confirmed that the signal (a) is within a range of a prescribed level. When the signal (a) is within this range, a sufficiently stable and quick tracking-servo lead-in can be executed. When the signal (a) is outside this range, a driving signal (c) is generated in accordance with a jumping direction by a driving signal generating circuit 7 by a signal from a control signal generating circuit 6, and applied to a moving means of a laser spot position through a driving circuit 4. In this way, the signal (a) goes into the range of a prescribed level, and in that case, a switching circuit 3 becomes an on-state by a signal (d) from the circuit 6, and a tracking loop becomes a closed loop.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to an apparatus for moving a recording/reproducing means such as a laser spot to a desired track on a recording medium by jumping.

<Prior Art and Problems> Conventionally, optical disk devices that use a disk-shaped recording medium and record and reproduce information by irradiating the disk-shaped recording medium with a laser spot are well known. In such an optical disk device, it is necessary to accurately position the laser spot on a desired track. Here, when performing a so-called track jump to move the laser spot from a predetermined track to another track,
Conventionally, the tracking servo is once opened in loop, a constant drive signal for moving the laser spot is supplied to the optical head to perform a track jump, and after the track jump is completed, the generation circuit generates the tracking servo again. was carried out.

However, when performing the above operations, the laser spot may not jump properly due to uneven track pitch formed on the disk-shaped recording medium, eccentricity of the disk-shaped recording medium, etc., and the laser spot may be separated from the desired track. In some cases, a generation circuit that generates a tracking servo loop may be used in the same state, and in that case, the servo cannot be pulled in quickly, the jump settling time becomes long, and this may become a factor in the instability of the tracking system servo. In such a case, it is difficult to perform a continuous jump operation in which jumping is repeated within a short period of time, and there is a problem in that the track access time becomes long.

<Object of the Invention> An object of the present invention is to provide a track jumping device that eliminates the above-mentioned conventional drawbacks and is capable of stable and accurate track jumping.

<Embodiments of the Invention> An embodiment of the present invention will be described below with reference to the drawings.0 Fig. 1 shows a drive circuit for a trunk jump device for an optical head in an optical disk device, showing the configuration of an embodiment of the present invention. FIG.

In the circuit shown in the figure, a tracking error signal (a) indicating a positional deviation between the laser spot and the track is obtained by a tracking error signal generation circuit 1, and this tracking error signal (a) passes through a phase compensation circuit 2 and then a switching circuit. 3 is turned on by the signal (d), the tracking error signal (a) is supplied to the drive circuit 4, and the drive circuit 4 drives the means for moving the laser spot position, thereby performing so-called track servo. .

On the other hand, the ) rack jump is started by receiving a jump command from the system controller 10 and turning off the switching circuit 3 by the control signal generating circuit 6, thereby once opening the tracking servo loop. At this time, data on the number of tracks to jump to is set in the counter 9 from the system controller 10.

Next, the drive signal (b) shown in FIG. 2(b) is generated in the drive signal generation circuit 7 by supplying the timing signal from the control signal generation circuit 6, and this drive signal (b) is passed through the drive circuit 4. A jump is executed by applying voltage to the moving means of the laser spot position. During this jump,
From the tracking error signal generation circuit 1, Fig. 2(a)
A tracking error signal shown in FIG. In this way, the laser spot can jump a predetermined number of tracks. In the jump state shown in FIG. 2(a) above, if the generation circuit turns on the switching circuit 3 at the end of the jump (t2) to generate a tracking servo loop, the waveform shown in 1a of FIG. 2(a) will be generated. As a result, the servo pull becomes unstable and the settling time becomes longer.

Further, this state may become a factor causing instability in the tracking system servo.

Therefore, here, the tracking error signal (a) is sent to the window comparator 5 at the end of the jump (t2).
and confirm that the tracking error signal (a) is within the range of ±Va. Tracking error signal (
In this range a), sufficiently stable and rapid tracking servo pull-in is possible.

Since the tracking error signal (a) is outside this range at t2 when the jump of the waveform shown in FIG. A drive signal (e) is generated according to the jumping direction and is applied to the laser spot position moving means through the drive circuit 4. In this way, the tracking error signal falls within the range of ±Va at time t3, and at that time, the signal (d) (second
As shown in FIG. 3(d), the switching circuit 3 is turned on, and the tracking servo loop becomes a generating circuit.

As described above, since the operation to convert the tracking servo loop into a generation circuit is always performed in a state where stable and quick servo pull-in is possible, as shown in Fig. 2 (a),
) A stable and accurate tracking jump can be performed as shown in the waveform shown in 2a.

It goes without saying that the present invention can also be applied to track jumps in read-only optical disc devices.

<Effects of the Invention> As described above, according to the present invention, a stable and reliable track jump with quick settling can be performed.

[Brief explanation of drawings]

FIG. 1 is a circuit block diagram of an embodiment of a track jump device according to the present invention, and FIG. 2 shows waveforms at various parts during a track jump. In the figure, l: Tracking error signal generation circuit. 2... Phase compensation circuit, 3... Switching circuit. 4...Drive circuit, 5...Window comparator. 6... Control signal generation circuit, 7... Drive signal generation circuit. 8... Waveform shaping circuit, 9... Counter, 10...
System Controller Representative Patent Attorney Takeshi Sugiyama (and 1 other person) Figure 1

Claims (2)

[Claims] (1) In a track jump device in which a tracking servo loop starts jumping as an open loop and closes the loop at the same time as jumping ends, a generation circuit that generates a tracking error signal indicating a deviation of the signal recording/reproducing means with respect to the track, and the tracking error signal. A track jump device comprising: a generation circuit that generates timing for closing the tracking servo loop based on the above. (2) The timing for closing the tracking servo loop is generated in accordance with the level of the tracking error signal, and if the signal level is outside a predetermined range, the signal is recorded and reproduced in the direction according to its polarity. 2. A track jump device according to claim 1, further comprising means for applying a drive signal for moving said signal recording/reproducing means to bring said signal recording/reproducing means within a predetermined range of a desired track.