JPS63293721A - Method for jumping track - Google Patents

Abstract

PURPOSE:To find out the moving distance of a spot even if a tracking error signal is a signal sampled by low sampling frequency by controlling a relative speed between a spot and a track so as to include the speed within a fixed range. CONSTITUTION:In the case of moving a spot from a current track to another track, fixed times T1, T2 (T2>=T1) are set up. When the time required for the movement of the spot only by one track is <=T1, a pickup is decelerated in the moving direction from the zero crossing of a tracking error signal in its on-track state up to its off-track state. When the time required for the movement of the spot only by one track is >=T2, the pickup is accelerated in the moving direction from the zero crossing of the tracking error signal in its on-track state up to its off-track state. Since the relative speed between the spot and the track is included within the set range, the moving distance of the spot can be found out only from the tracking error signal even if the sampling frequency is low.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a track jumping method for moving a pickup spot onto a track of a disc in a compact disc player or the like.

BACKGROUND OF THE INVENTION FIG. 3 is a block diagram of a recording signal reading section of a compact disc (CD) player. In FIG. 3, numeral 1 is a cross section of the disk, 2 is a pink-up, and 3 is a vertical cross section of tracks on which signals are recorded, which are arranged substantially parallel to each other at a pitch of J=1.6 μm. Pinkup focuses laser light as a spot on the disk surface,
From the reflected light, a recording signal and a tracking error signal corresponding to the amount of deviation between the spot position and the track position on the disk are read. The tracking drive signal is a signal that drives the pickup in a direction perpendicular to the track.

FIG. 2 is a waveform diagram of a tracking error signal and a tracking drive signal in a conventional track jump method. Figure 2 (al is a waveform diagram of the tracking error signal, and Figure 2 (b) is a waveform diagram of the tracking drive signal. The conventional track jump method detects the midpoint between the current track and the target track. Then, the pickup is accelerated in the direction of the target track with a constant driving force V until the spot position reaches the halfway point, and after reaching that halfway point, it is decelerated with a constant driving force ■ for the acceleration time T. is configured to do so.

With the above configuration, at the end of the track jump, the relative velocity between the spot and the truck is close to O, and the spot position is near the target trunk. (For example, Japanese Unexamined Patent Publication No. 52-26802) Problems to be Solved by the Invention However, in the above configuration, when the distance to move the spot is long, the pink-up is accelerated for a long time, and the spot relative to the track is The problem was that the relative speed of If this relative speed is large, the change in the tracking error signal becomes drastic, and in the case of a digital tracking servo system with a low sampling frequency, the zero crossing of the tracking error signal cannot be read, and the travel distance of the pickup can be determined only from the change in the tracking error signal. I won't be able to do that.

In view of the above-mentioned problems, the present invention provides a track jumping method that makes it easy to keep the relative speed between the track and the spot below a certain value.

Means for Solving the Problems In order to solve the above problems, the truck jumping method of the present invention decelerates the pickup when the relative speed between the spot and the truck becomes too large, and when the relative speed becomes too small. It has a configuration that accelerates the pickup.

Effect of the Invention Since the above-described configuration allows the relative speed between the spot and the track to be within the set range, the zero crossing of the tracking error signal can be easily read even in a digital tracking servo system with a low sampling frequency. , the moving distance of the spot can be determined only from the tracking error signal.

EXAMPLE A method of track jumping which is an example of the present invention will be described below with reference to the drawings.

FIG. 1 is a waveform diagram of a tracking error signal, an on-track signal, and a tracking drive signal according to a trunk jump method according to an embodiment of the present invention. Figure 1 (a
1 is a waveform diagram of the tracking error signal, and T
b) is a waveform diagram of the on-track signal which becomes low level (“θ”) in the on-track state and becomes high level (“1”) in the off-trunk state, and Fig. 1 (C) is a waveform diagram of the tracking drive signal. FIG. In the present invention, when moving a spot from a current track to another track (destination track), a certain time 'r,, T2 (Tz≧
Set T1, and the time required for the spot to move one track is T. In the following cases, the pink amplifier is moved in the direction of movement from when the tracking error signal crosses zero during the on-track state until it becomes off-track. If the time required for the spot to move one track is T2 or more, the pickup is accelerated in the moving direction from when the tracking error signal crosses zero during on-track until it becomes off-track. It is composed of

With the above configuration, when the relative speed between the spot and the track becomes too large, the pickup is decelerated, and when the relative speed becomes too small, the pickup is accelerated.

As described above, according to this embodiment, the relative velocity between the spot and the track is controlled so that it is within a predetermined range, so even in a digital tracking servo system with a low sampling frequency, the zero crossing can be determined from the digital tracking error signal. By counting the number of moving tracks of the spot, the number of moving tracks can be determined.

Effects of the Invention As described above, the present invention controls the relative velocity between the spot and the track so that it is within a certain range, so that even if the tracking error signal is a signal sampled at a low sampling frequency, The moving distance of the spot can be determined from this signal, which is extremely effective in practice.

[Brief explanation of the drawing]

FIG. 1 shows a tracking error signal ((a)), an on-track signal ((bl)), and a tracking drive signal (((a)) of a track jump method in an embodiment of the present invention.
C)) waveform diagram, Figure 2 is a waveform diagram of the tracking error signal ((al) and tracking drive signal ([b)) in the conventional trunk jump method, and Figure 3 is the waveform diagram of the signal reading part of a CD player. FIG. I...disc, 2...pink up, 3...track. Name of agent: Patent attorney Toshio Nakao (Figure 1 f/I) Figure 2

Claims (1)

[Claims] It has a standard for determining whether it is on-track or off-track, and accelerates or decelerates the pickup in a direction perpendicular to the track during the period from when the tracking error signal crosses zero during on-track to when it becomes off-track. The method of track jumping is characterized in that the pickup is decelerated when the time it takes for a spot to pass one track is equal to or greater than a predetermined value, and the pickup is accelerated when the time required for a spot to pass through one track is equal to or greater than a predetermined value.