JPH0743899B2 - Track jump device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a track jump device used for an optical information recording / reproducing device or the like.

2. Description of the Related Art FIG. 2 (a) shows a track jump device of a conventional optical disk device, 1 is an optical disk as a recording medium,
Reference numeral 2 is a spindle motor for rotating the optical disk 1, 3 is a semiconductor laser that generates a beam, and an objective that focuses the beam on a minute spot light and irradiates the optical disk 1 with the reflected light. The optical pickup includes a lens and an optical system that receives reflected light from the lens and outputs a sinusoidal track error signal or the like.

The objective lens of the optical pickup 3 uses the optical disc 1 so that the beam follows the tracks of the optical disc 1 (tracking), or seeks and jumps closely between the tracks.
It can be moved in the radial direction.

Reference numerals 4, 5, 6, and 7 denote an error amplifier, a phase compensation circuit, a switch, and an objective lens drive circuit that form a tracking servo control loop for controlling the beam of the optical pickup 3 to follow the track of the optical disc 1. is there. The error amplifier 4 outputs a signal A obtained by amplifying the track error signal from the optical pickup 3, and the objective lens drive circuit 7 outputs a drive current to a tracking coil (not shown) for controlling the objective lens.

Reference numeral 8 denotes a drive control circuit (DR which controls tracking and track jump of the objective lens as described later.
C) and 9 are relative speed detection circuits that detect the relative speed of the objective lens with respect to the track of the optical disc 1 by the track error signal A from the error amplifier 4, and 10 is composed of a time constant circuit and the like, and is binary when a track jump is performed. The command speed circuit sets the command speed by the conversion signal B, and the drive control circuit 8 sets the jump direction (polarity) DIR of the command speed.

Reference numeral 11 denotes a binarization circuit for binarizing the track error signal A from the error amplifier 4, and reference numeral 12 denotes a binarization signal B from the binarization circuit 11 so that the track error signal A is in the middle of the tracks. A "0" cross detection circuit 13 for detecting crossing of "0" level representing a point is a switch which is turned off at the time of tracking and turned on at the time of track jump.

Next, the operation of the above conventional example will be described with reference to FIG.

When switching from the tracking servo control loop to the track jump speed control loop, the drive control circuit 8 turns off the switch 6 and turns on the switch 13, and instructs the command speed circuit 10 to specify the track jump direction (polarity) of the objective lens. To do.

In this case, the command speed circuit 10 outputs the binarized signal B and the speed signal C corresponding to the command speed depending on the polarity thereof, and the detection pulse D from the "0" cross detection circuit 12 (when the next track is reached ) To reduce the command speed with a time constant circuit.

Therefore, when the objective lens overshoots the next track and then returns to the direction of that track, and overshoots that track again and the "0" cross detection circuit 12 outputs the detection pulse E again, the drive control circuit 8
Turns on the switch 6 and turns off the switch 13 to switch from the track jump speed control loop to the tracking servo control loop.

SUMMARY OF THE INVENTION However, in the above conventional track jump device,
By detecting that the track error signal A has become the "0" level for the second time, the track jump speed control loop is switched to the tracking servo control loop, so that the objective lens reaches only just before the target track due to disturbance or the like. Otherwise, the "0" level of the track error signal A cannot be detected, so that there is a problem that the track jump speed control loop cannot be switched to the tracking servo control loop.

In view of the above problems, it is an object of the present invention to provide a track jump device capable of reliably switching from a track jump speed control loop to a tracking servo control loop.

Means for Solving the Problems In order to achieve the above object, the present invention detects a peak value after a track error signal has reached a “0” level during track jump control, and after detecting this peak value, a track error is detected. When it is detected that the signal is within a predetermined positive and negative level centered on the "0" level, the control is switched to the track following control.

Operation According to the present invention, by detecting the peak value after the track error signal has reached the "0" level, the objective lens can detect when the objective lens overshoots the target track and then starts returning to the target track. By detecting that the track error signal is within a predetermined positive and negative level centered on the “0” level, it is possible to detect that the objective lens is close to the target track. For example, when the objective lens reaches just before the target track, the objective lens can follow the target track even if the track jump speed control loop is switched to the tracking servo control loop.

Embodiments Embodiments of the present invention will be described below with reference to the drawings. First
FIG. 1A is a block diagram showing an embodiment of the track jump device according to the present invention, and FIG. 1B is FIG. 1A.
3 is a timing chart showing main signals of the track jump device of FIG. 1, and the same components as those shown in FIG. 2 are designated by the same reference numerals.

In FIG. 1 (a), 1 is an optical disk which is a recording medium, 2 is a spindle motor for rotating the optical disk 1, 3 is a semiconductor laser which generates a beam, and this beam is focused into a minute spot light. The optical pickup includes an objective lens that irradiates the optical disc 1 and collects the reflected light, and an optical system that receives the reflected light and outputs a sinusoidal track error signal or the like.

The objective lens of the optical pickup 3 uses the optical disc 1 so that the beam follows the tracks of the optical disc 1 (tracking), or seeks and jumps closely between the tracks.
It can be moved in the radial direction.

Reference numerals 4, 5, 6, and 7 are an error amplifier, a phase compensation circuit, a switch, and an objective lens drive circuit that form a tracking servo control loop for controlling the beam of the optical pickup 3 to follow the track of the optical disc 1. . The error amplifier 4 outputs a signal A obtained by amplifying the track error signal from the optical pickup 3, and the objective lens drive circuit 7 outputs a drive current to a tracking coil (not shown) for controlling the objective lens.

80 is a drive control circuit (DR which controls tracking of the objective lens and track jump as described later.
C) and 9 are relative speed detection circuits that detect the relative speed of the objective lens with respect to the track of the optical disc 1 by the track error signal A from the error amplifier 4, and 10 is composed of a time constant circuit and the like, and is binary when a track jump is performed. The command speed circuit sets the command speed by the conversion signal B, and the drive control circuit 8 sets the jump direction (polarity) DIR of the command speed.

Reference numeral 11 denotes a binarizing circuit for binarizing the track error signal A from the error amplifier 4, and reference numeral 12 denotes the binarizing signal B from the binarizing circuit 11 so that the track error signal A crosses a "0" level. The "0" cross detection circuit 13 for detecting the fact is a switch that is turned off during tracking and turned on during a track jump.

14 is a peak value detection circuit which is activated by the rise of the track jump speed control loop switching signal G from the drive control circuit 80 and detects the second peak value of the track error signal A, and 15 is the peak value detection circuit 14 Is a threshold circuit that is activated by the detection signal E ₁ of ₁ to detect that the track error signal A is within a predetermined positive and negative level centered on the “0” level.

Next, the operation of the above embodiment will be described with reference to FIG.

When switching from the tracking servo control loop to the track jump speed control loop, the drive control circuit 80 turns off the switch 6 and turns on the switch 13, activates the peak value detection circuit 14, and also directs the command speed circuit 10 to the objective. Command the track jump direction (polarity) of the lens.

In this case, the command speed circuit 10 outputs the binarized signal B and the speed signal C corresponding to the command speed depending on the polarity thereof, and the detection pulse D from the "0" cross detection circuit 12 (when the next track is reached ) To reduce the command speed with a time constant circuit. Therefore, the objective lens begins to return in the direction of the next track after overshooting the next track.

When the objective lens starts returning in the direction of the track, the track error signal A reaches the peak value, so the peak value detection circuit 14 outputs the detection signal E ₁ and activates the threshold circuit 15.

The threshold circuit 15 outputs a detection signal F to the drive control circuit 80 when the track error signal A detects that the track error signal A is within a predetermined positive and negative level around the "0" level, and the drive control circuit 80 turns on the switch 6. The track jump speed control loop is switched to the tracking servo control roof by turning the switch 13 on and off.

Therefore, according to the above embodiment, during the track jump speed control, after the peak value detection circuit 14 detects the second peak value of the track error signal A, the threshold value circuit 15 sets the track error signal A to "0" level. In order to switch to the tracking servo control loop when it is detected that the center is within the predetermined positive and negative levels, the track jump speed control loop is used even when the objective lens reaches only just before the target track due to disturbance or the like. Can be reliably switched to the tracking servo control loop.

Further, in the above-mentioned embodiment, the objective lens moves the target track to 2
In order to switch from the track jump speed control loop to the tracking servo control loop without overshooting once, a margin can be provided on the undershoot side as viewed from the target track, thus enabling stable switching operation.

As described above, according to the present invention, the peak value after the track error signal becomes the "0" level is detected during the track jump control, and after the peak value is detected, the track error signal is "0". Since it is configured to switch to the track follow-up control when it is detected that the value is within a predetermined positive or negative level centered on the level, the objective lens is detected by detecting the peak value after the track error signal becomes "0" level. Can detect when it starts to return to the target track after overshooting the target track, and by detecting that the track error signal is within a predetermined positive and negative level around the "0" level, the objective lens can Since the proximity to the track can be detected, the objective lens reached only just before the target track due to disturbance or the like. In this case, even if the track jump speed control loop is switched to the tracking servo control loop, the objective lens can follow the target track.

[Brief description of drawings]

1 (a) is a block diagram showing an embodiment of the track jump device according to the present invention, and FIG. 1 (b) is a timing chart showing main signals of the track jump device of FIG. 1 (a). 2 (a) is a block diagram showing a conventional track jump device, and FIG. 2 (b) is a timing chart showing main signals of the track jump device of FIG. 2 (a). 14 …… Peak value detection circuit, 15 …… Threshold circuit, 80 …… Drive control circuit.

Claims (1)

[Claims] 1. A first detecting means for detecting a "0" level which represents an intermediate point between tracks of a track error signal during track jump control, and a peak after the "0" level is detected. Second detecting means for detecting the peak, third detecting means for detecting that the track error signal represented by positive and negative values centered on the “0” level after detecting the peak is a predetermined level, and the third detecting means. A track jump device having control switching means for switching to track following control when the detection means detects that the track error signal is within the predetermined range.