JPH0438685A - Track jump device - Google Patents

Abstract

PURPOSE:To enable an objective lens to follow up a target track by switching control into track follow-up control when it is detected that a tracking error signal is within prescribed positive and negative levels around a tracking error signal '0' level after a peak value is detected after the tracking error signal '0' level is attained. CONSTITUTION:At the time of track jump speed control, when it is detected that the tracking error signal A is within the prescribed positive and negative levels around the '0' level by a threshold circuit 15 after the second peak value of the tracking error signal A is detected by a peak value detection circuit 14, a control loop is switched into a tracking servo control loop. Accordingly, even when the objective lens reaches only just before the target track because of disturbance, etc., the control loop can be surely switched from a track jump speed control loop into the tracking servo control loop. Thus, the objective lens can be made to follow up surely the target track.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a trunk jump device used in optical information recording/reproducing devices and the like.

Conventional technology FIG. 2(a) shows a conventional optical disk device Torano 2.
・＼-7 Indicates a Kuji Yump device, where 1 is an optical disk as a recording medium, 2 is a spindle motor for rotating the optical disk 1, and 3 is a semiconductor laser that generates a beam and focuses this beam into a minute spot light. The optical pink-up includes an objective lens that emits light onto the optical disk 1 and focuses the reflected light, and an optical system that receives the reflected light and outputs a sinusoidal tracking error signal.

The objective lens of the optical pickup 3 is configured to move the optical disc 1 so that the beam follows the tracks of the optical disc 1 (tracking), or closely seeks or jumps between tracks.
can be moved minutely in the radial direction.

4.5.6.7 are an error amplifier, a phase compensation circuit, a switch, and an objective lens drive circuit, respectively, which constitute a tracking servo control loop for controlling the beam of the optical pickup 3 to follow the track of the optical disk 1. be. The error amplifier 4 outputs a signal A obtained by amplifying the tracking error signal from the optical pickup 3, and the objective lens drive circuit 3 and path 7 output a drive current to a tracking coil (not shown) for controlling the objective lens. do.

8 is a drive control circuit (D) that controls objective lens tracking and track jump as described later.
H, C), 9 is a relative speed detection circuit that detects the relative speed of the objective lens with respect to the track of the optical disk 1 based on the track error signal A from the error amplifier 4, and 10 is a time constant circuit, etc. The command speed is set by the binarization signal B, and the jump direction (polarity) D of the command speed is determined by the drive control circuit 8.
This is a command speed circuit in which IR is set.

11 is a binarization circuit that binarizes the track error signal A from the error amplifier 4; 12 is a binarization circuit that causes the track error signal A to cross the rOJ level by the binarization signal B from the binarization circuit 11; The "o" cross detection circuit 13 is a switch that is turned off during tracking and turned on during trunk jump.

Next, the operation of the above conventional example will be explained with reference to FIG. 2(b).

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 also instructs the command speed circuit 10 about the track jump direction (polarity) of the objective lens. do.

In this case, the command speed circuit 1o outputs a speed signal C according to the command speed using the binarization signal B and its polarity, and outputs a speed signal C corresponding to the command speed "O".
The command speed is decreased by the time constant circuit from the detection pulse D from the cross detection circuit 12 (when the next track is reached).

Once the objective lens overshoots the next track, it returns to the direction of that track, overshoots that track again, and when the rOJ cross detection circuit 12 outputs the detection pulse E again, the drive control circuit 8 switches 6 is turned on and switch 13 is turned off to switch from the trunk jump speed control loop to the tracking servo control loop.

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Problems to be Solved by the Invention However, with the above-mentioned conventional truck jump device,
By detecting that the track error signal A has reached the "0" level for the second time, the objective lens can only reach just before the target track due to disturbances etc. in order to switch from the track jump speed control loop to the tracking servo control loop. If not, there is a problem that the [04 level of the tracking error signal A cannot be detected, and therefore the track jump speed control loop cannot be switched to the tracking servo control loop.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a trunk jump device that can reliably switch 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 the peak value after the track error signal reaches the [04 level during track jump control, and detects the peak value of the track error signal after detecting this peak value. When it is detected that the current level is within a predetermined positive or negative level around the Oj level, the control is switched to track following control.

According to the present invention, with the above configuration, by detecting the peak value after the trunk error signal reaches the rOJ level, it is possible to detect when the objective lens begins to return to the target track after automatically seating the target trunk. By detecting that the trunk error signal is within a predetermined positive and negative level around the rOJ level, it is possible to detect that the objective lens is close to the target track. When the objective lens reaches only just before the target trunk, the objective lens can be made to follow the target track even if the trunk jump speed control loop is switched to the tracking servo control loop.

EXAMPLES Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1(a) is a block diagram showing an embodiment of a 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). Components that are the same as those shown in FIG. 2 are given the same reference numerals.

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

The objective lens of the optical pickup 3 is configured to move the optical disc 1 so that the beam follows the tracks of the optical disc 1 (tracking), or closely seeks or jumps between tracks.
can be moved minutely in the radial direction.

4.6.6.7 are an error amplifier, a phase compensation circuit, a switch, and an objective lens drive circuit, respectively, which constitute a tracking servo control loop for controlling the beam of the optical pickup 3 to follow the track of the optical disk 1. be. The error amplifier 4 outputs a signal A obtained by amplifying the tracking 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 (which controls the tracking and tracking of the objective lens, as will be described later).
DRC), 9 is a relative speed detection circuit that detects the relative speed of the objective lens with respect to the track of the optical microscope 1 based on the track error signal A from the error amplifier 4; 10 is a time constant circuit, etc.; The command speed is set by the value conversion signal B, and the jump direction (polarity) D of the command speed is determined by the drive control circuit 8.
This is a command speed circuit in which IR is set.

11 is a binarization circuit that binarizes the track error signal A from the error amplifier 4; 12 is a binarization circuit that causes the track error signal A to cross the "o" level by the binarization signal B from the binarization circuit 11; The "o" cross detection circuit 13 is a switch that is turned off during tracking and turned on during track jump.

14 is a peak value detection circuit that is activated by the rise of the track jump speed control loop switching signal 0 from the drive control circuit 8o and detects the second peak value of the track error signal A; 15 is a peak value detection circuit from the peak value detection circuit 14; This is a threshold circuit that is activated by the detection signal E1 of the track error signal A and detects that the track error signal A is within a predetermined positive or negative level centered on the rOJ level.

Next, the operation of the above embodiment will be explained with reference to FIG. 1(b).

When switching from the tracking servo control loop to the track jump speed control loop, the drive control circuit 8o turns off the switch 6 and turns on the switch 13, starts the peak value detection circuit 14, and also outputs the objective signal to the command speed circuit 1o. Command the track jump direction (polarity) of the lens.

In this case, the command speed circuit 10 outputs a speed signal C according to the command speed using the binarization signal B and its polarity, and outputs a speed signal C corresponding to the command speed "o".
The command speed is decreased by the time constant circuit from the detection pulse D from the cross detection circuit 12 (when the next track is reached). Therefore, the objective lens begins to move back toward the next track after oversheeting that track.

When the objective lens begins to return to its track direction, the trunk error signal A reaches its peak value, so the peak value detection circuit 14 outputs its detection signal E1, and the threshold value circuit 1
6.

When the threshold circuit 16 detects that the tracking error signal A is within a predetermined positive or negative level around the "o" level, it outputs the detection signal F to the drive control circuit 8o, and the drive control circuit 80 turns on the switch 6. on,
Switch 13 is turned off to switch from the track jump speed control loop to the tracking servo control roof.

Therefore, according to the above embodiment, after the second peak value of the trunk error signal is detected by the peak value detection circuit 14 during trunk jump speed control, the threshold value circuit 16
When it is detected that the tracking error signal A is within a predetermined positive and negative level around the rOJ level, the control loop is switched to the tracking servo control loop. Even in such a case, the trunk jump speed control loop can be reliably switched to the tracking servo control loop.

Furthermore, in the above embodiment, the objective lens separates the target track by two
In order to switch from the track jump speed control loop to the tiger jump servo control loop without overshooting, a margin can be provided on the undershoot side as viewed from the target trunk, thus making it possible to perform stable switching operations.

As described in detail, the present invention detects the peak value after the trunk error signal reaches r0 level during track jump control, and after detecting this peak value, the trunk error signal d; Since the control is switched to track following control when it is detected that the track error signal is within a predetermined positive and negative level, the objective lens overshoots the target track by detecting the peak value after the track error signal reaches the rOJ level. - It is possible to detect when the track error signal starts to return to the target track after the track error signal rO
By detecting that the objective lens is close to the target track by detecting that it is within a predetermined positive and negative level centered on the J level, it is possible to detect that the objective lens is close to the target track due to disturbances etc. Even if the track jump speed control loop is switched to the tracking servo control loop when only the target track is reached, the objective lens can be made to follow the target track.

[Brief explanation of drawings]

FIG. 1(a) is a block diagram showing an embodiment of a track jump device according to the present invention, and FIG. 1(b) is a block diagram showing an embodiment of a track jump device according to the present invention.
Fig. 2(a) is a block diagram showing the conventional track jumping device; Fig. 2(b) is a timing chart showing the main signals of the track jump device in Fig. 2(a).
3 is a timing chart showing main signals of the track jump device of FIG. 14...Peak value detection circuit, 16...Threshold value circuit, 8
0...Drive control circuit. Name of agent: Patent attorney Shigetaka Awano and one other person

Claims (1)

[Claims] a first detection means for detecting a peak value after the track error signal reaches the "0" level during track jump control, and a track error signal at the "0" level after the first detection means detects the peak value; a second detecting means for detecting that the track error signal is within a predetermined positive and negative level centered on the "0"level; A track jump device having means for switching to track following control when detection is detected.