JP2797562B2 - Tracking method for optical recording device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording apparatus for recording or reproducing information using light, and more particularly to a tracking method therefor.

[Conventional technology]

FIG. 4 shows a configuration of a conventional optical disk optical head in an optical recording apparatus. Light emitted from the laser light source 21 is focused on the optical recording medium 3 by the condenser lens 2, and reflected light from the optical recording medium is separated by the beam splitter 4 and received by the photodetector 5. In an optical disc or the like, a tracking groove is provided on an optical recording medium in order to record and reproduce information along a predetermined track. Fig. 5 (a)
FIG. 5 (b) shows a track error signal obtained by a push-pull method or the like based on the position of the spot center on the optical recording medium. When the relative position between the spot and the groove on the optical recording medium is shifted, a track error signal that makes a zero cross at the center of the recording track 10 as shown in FIG. 5 can be obtained. The tracking operation can be realized by performing feedback control on the zero cross point of the track error signal. Such a tracking operation is performed by moving the entire optical head or the condensing lens in the direction perpendicular to the track error.

[Problems to be solved by the invention]

In the tracking operation as described above, a track jump to an adjacent track or the like is performed according to the following procedure. First, the feedback control is turned off. Next, the entire optical head or the condenser lens is moved by a predetermined amount. When the spot is presumed to be on the desired track,
The feedback control is turned on again.

In this tracking operation, since the feedback control is not performed while the spot is moving between the tracks, the track is likely to be displaced due to an external impact or the like.
Further, when the track interval is partially changed, when the feedback control is turned on again, the tracking is temporarily unstable because the spot is not accurately on the track.

An object of the present invention is to provide a tracking method for an optical recording device that does not cause the above-described problems.

[Means for solving the problem]

The present invention is directed to an optical recording apparatus for recording and reproducing information by condensing light emitted from a light source as a minute spot on a recording track of an optical recording medium, wherein a plurality of spots are formed on the optical recording medium. And at least one spot is arranged on a recording track, and the remaining spots are arranged between the recording track and a recording track adjacent to the recording track, and are independently detected from each of the plurality of spots. While sequentially selecting the track error signals, the tracking control is performed with the selected track error signal, and the track error of the selected spot is moved to the zero cross point, thereby moving the entire plurality of spots in the track horizontal direction. It is characterized by the following.

〔Example〕

FIG. 1 shows an optical recording apparatus embodying an embodiment of the present invention,
FIG. 2 shows an arrangement of light-converging spots for explaining one embodiment.

As the laser light source 1, an array type laser that emits three beams is used, and the photodetector 5 also uses an array type. The light emitted from the laser light source 1 is condensed on the recording medium 3 as three minute spots 11, 12, and 13 by the condenser lens 2, and the reflected light is separated by the beam splitter 4 and detected by the photodetector 5.

The photodetector 5 detects track error signals for these three spots by a push-pull method. The track error signal is sent to the feedback control circuit 6
Is transmitted to the lens driving circuit 7 via the optical pickup and moves the condenser lens 2 to realize a tracking operation.

As shown in FIG. 2, the arrangement of the three focusing spots is as follows.
When the focused spot 11 is placed on the recording track 10, the other two focused spots 12 and 13
5 and are arranged substantially evenly in the track orthogonal direction and the track circumferential direction.

When the spot 11 is at the center of the track 10, the track error signals A, B, and C due to the spots 11, 12, and 13 are at the positions of A, B, and C in FIG. Selects the signal A, and receives the signal A via the feedback control circuit 6 and the lens driving circuit 7 according to the signal A.
Is controlled.

When jumping from the recording track 10 to the recording track 15, first, the feedback control circuit 6 switches the input from the track error signal A to the track error signal B and performs tracking so that the signal B becomes zero (FIG. 3 (b)). . At this time, the three focused spots move simultaneously. By this tracking, control is performed so that the focused spot 12 is located between the recording tracks 10 and 15.

Next, the feedback control circuit 6 switches the input from the track error signal B to the track error signal C, and performs tracking so that the signal C becomes zero (FIG. 3 (c)). By this tracking, control is performed so that the focused spot 13 is located at the center of the recording track 15.

Next, the feedback control circuit 6 switches the input from the track error signal C to the track error signal A again, and performs tracking so that the signal A becomes zero (FIG. 3 (d)). By this tracking, control is performed so that the focused spot 11 is located between the recording tracks 10 and 15.

By repeating the same procedure,
11 can be moved to the center of the adjacent track 15.

Since the above method is executed only by switching the input of the feedback control, the tracking operation does not become unstable.

In the above embodiment, the number of the converging spots is three. However, the method of the present invention can be implemented even when more than three converging spots are used. These plurality of converging spots may be generated by a diffraction grating.

In the above embodiment, the track error signal is detected by the push-pull method. However, the three-beam method or the sample servo method can be used.

〔The invention's effect〕

According to the present invention, a plurality of spots are formed on an optical recording medium, at least one of the spots is arranged on a recording track, and the remaining spots are recorded on a recording track and a recording track adjacent to the recording track. It is placed between the track and the track error signal detected independently from each of the plurality of spots is sequentially selected, and tracking control is performed with the selected track error signal, and the track error of the selected spot is zero-crossed. By moving to the point, the entire plurality of spots move in the track lateral direction, so that a stable tracking operation can be performed in the optical recording apparatus.

[Brief description of the drawings]

 FIG. 1 is a diagram showing an optical recording apparatus embodying the present invention, FIG. 2 is a diagram showing an arrangement of condensed spots, FIG. 3 is a diagram showing a track error signal, FIG. 4, FIG. The figure shows the prior art. DESCRIPTION OF SYMBOLS 1 ... Laser light source 2 ... Condensing lens 3 ... Recording medium 4 ... Beam splitter 5 ... Photodetector 6 ... Feedback control circuit 7 ... Lens drive circuit 10, 15 ... Recording tracks 11,12, 13 …… Condensing spot

Claims (1)

(57) [Claims] 1. An optical recording apparatus for recording and reproducing information by focusing light emitted from a light source on a recording track of an optical recording medium as a minute spot, wherein a plurality of spots are formed on the optical recording medium. At least one of the spots is arranged on a recording track, and the remaining spots are arranged between the recording track and a recording track adjacent to the recording track, and are independently detected from each of the plurality of spots. While sequentially selecting the track error signals, the tracking control is performed with the selected track error signal, and the track error of the selected spot is moved to the zero cross point,
A tracking method for an optical recording apparatus, wherein a whole of a plurality of spots is moved in a track lateral direction.