JPH0793765A - Tracking servo device - Google Patents

Abstract

PURPOSE:To enhance the precision for moving an optical pickup to a target track. CONSTITUTION:In a tracking servo device for moving the optical pickup to the target track on a disk, by an edge detection circuit 3, a main signal detected by the optical pickup is envelope detected. After the detection, the signal is formed to an on-track signal of a rectangular pulse, and the edge of the pulse is detected, and by a track traverse direction discrimination part 5, a track traverse direction in the direction where the optical pickup is moved is discriminated from a tracking error signal whose phase is different from each other when the optical pickup is moved from the inner periphery to the outer periphery of the disk or reversely. Then, by a track traverse detector 6, the track traverse in the direction where the optical pickup is moved is detected from the detected edge and the discriminated track traverse direction, and the number of the detected track traverses is counted, and when the number becomes a presribed value, the track movement is ended.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tracking servo device for an optical disc player, and more particularly to improving the accuracy with which an optical pickup moves to a target track.

[0002]

2. Description of the Related Art Conventionally, as a technology in such a field, a CD (Compact Disc), LD (LASER Disc), MD (M
There is a tracking servo device for a player. The high-speed cueing of the target song by this tracking servo device calculates the number of tracks from the track currently located to the track on which the target song is recorded. For example, the number of tracks crossed by the optical pickup is counted to determine the predetermined track. The optical pickup is moved until it crosses the number. The number of tracks traversed by the optical pickup is obtained by counting the number of pulses obtained by binarizing the envelope of the RF signal which is the tracking error signal or the main signal.

[0003]

However, in the conventional tracking servo device for counting the number of tracks, the track is moved in the direction opposite to the optical pickup moving direction due to the vibration of the equipment such as the player or the eccentric component of the disk. There is a problem that counting is performed even when it crosses, and therefore, when the optical pickup is moved according to this count number, the movement amount becomes smaller than a predetermined number of tracks.

Therefore, in view of the above problems, it is an object of the present invention to provide a tracking servo device capable of accurately counting the number of tracks to be moved by an optical pickup even if there is vibration on the device or an eccentric component of the disk. And

[0005]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a tracking servo apparatus for moving an optical pickup to a target track on a disk, wherein an edge detection circuit is a main unit that is detected by the optical pickup. The signal is envelope-detected, and after this detection, it is formed into a rectangular pulse on-track signal, and the edge of this pulse is detected.The track crossing direction determination unit detects the phase when the optical pickup moves from the inner circumference of the disk to the outer circumference or vice versa. Discriminates the track crossing direction of the direction in which the optical pickup should move from different tracking error signals,
The track crossing detector detects track crossing in the direction in which the optical pickup should move from the detection edge and the discriminated track crossing direction, and when the number of detected track crossings is counted and reaches a predetermined value, the track movement is completed.

Further, a track reverse crossing detector for detecting track crossing opposite to the direction in which the optical pickup should move is provided, and the track crossing detector detects the track crossing from the number counted by the track crossing detector. Subtract a number.

[0007]

According to the tracking servo device of the present invention, the main signal detected by the optical pickup is envelope-detected, and after this detection, it is formed into an on-track signal of a rectangular pulse and the edge of this pulse is detected. From the outer periphery or vice versa, the track crossing direction of the direction in which the optical pickup should move is determined from the tracking error signals having different phases when the optical pickup moves, and the optical pickup moves from the detection edge and the determined track crossing direction. Track crossing in the right direction is detected, and when the number of detected track crossings is counted and reaches a predetermined value, track movement is completed, so even if there is an influence due to vibration of equipment such as a player or an eccentric component possessed by the disc. Crosses the track only in the optical pickup movement direction By counting the number was, it becomes possible to accurately count the number of tracks which the optical pickup has moved.

Further, since the track crossing opposite to the direction in which the optical pickup should move is detected, and the track crossing in the opposite direction is subtracted from the track crossing in the direction in which the optical pickup should move. It is possible to eliminate the number of track crossings in the same direction as the moving direction of the optical pickup, which is included due to the vibration of equipment such as the above and the periodicity of the eccentric component of the disk.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a track number crossing control circuit in a tracking servo device according to a first embodiment of the present invention. As shown in the figure, the track number crossing control circuit includes, for example, an envelope detector 1 for envelope detecting a FR signal of an output beam spot by the 3-pot method in a tracking servo device of an optical pickup of a CD, and an envelope detector 1 A comparator 2 that inputs a signal to one side and a reference voltage (Vref1) to the other side to form an on-track signal, a fall detector 3 that detects a fall of the on-track signal of the comparator 2, and a 3-pot method A tracking error signal composed of a sub beam is input to one side and the reference voltage (V
ref2) is input, and the signal from the comparator 4 and the optical pickup are "L (low)" when moving from the inner circumference to the outer circumference, and "H (high)" when moving from the outer circumference to the inside. The logical product of the signals from the track crossing direction discriminator 5 and the trailing edge detector 3 and the track crossing direction discriminator 5 is formed by the exclusive OR circuit for inputting the moving direction switching signal and shaping the waveform. Therefore, the track crossing detector 6 for detecting the track crossing only in the direction in which the optical pickup should move, the counter 7 connected to the track crossing detector 6 for counting only the track crossing in the forward direction, and the count of the counter 7 It is provided with a comparator 8 which compares the track crossing set value and completes the track movement when they match.

FIG. 2 is a diagram showing signal waveforms for explaining the operation of the track number crossing control circuit of FIG. In this figure (a), the optical pickup goes from the inner circumference to the outer circumference of the disc, and in this figure (b), the signal waveform of each part when the optical pickup goes from the outer circumference to the inner circumference of the disc is shown. RF which is the main signal to 1
Although the signal and the on-track signal which is the output signal of the comparator 2 are the same, the phase of the tracking signal which is the input signal of the comparator 4 is inverted because the moving directions of the optical pickup are opposite. Therefore, the track crossing direction can be determined. Therefore, the counting can be performed only when the direction in which the optical pickup should move by the track crossing detector 6 matches the track crossing direction. On the contrary, if the direction in which the optical pickup should move and the cross-track direction do not match, the count is not performed. For example, when the direction in which the optical pickup should move is the forward direction and the direction of the track crossing coincides with the direction of the track crossing, the number of track crossing is counted, but the track crossing direction is changed due to the vibration with respect to the player and the eccentricity of the disc. If it is reversed, the number of crossing tracks will not be counted. Thus, the accuracy of movement of the optical pickup is improved.

By the way, due to the vibration with respect to the player and the eccentricity of the disc, the crossing of tracks has the repeatability in the forward direction and the reverse direction instead of the one direction. That is, the crossing of tracks due to these disturbances is in the opposite direction to the direction in which the optical pickup should move, and then tries to return to the original position by the amount of the reverse movement. In this way, when returning to the original position, since it coincides with the direction in which the optical pickup should move, the above-described track number crossing control circuit counts track crossing in this case, and therefore vibration due to the player and eccentricity of the disc There is a problem that the number of track crossings is not sufficiently removed. Therefore, the solution to this problem will be described below.

FIG. 3 is a diagram showing a track number crossing control circuit in a tracking servo device according to a second embodiment of the present invention. In this figure, the dotted line frame portion has the same configuration as the dotted line frame portion, and the configuration portion different from FIG. 1 includes an inverter 10 for inverting the movement direction switching signal, an output of the inverter 10 and an output of the comparator 4. There is an exclusive OR circuit 11 for inputting the following, and a track backward crossing detector 12 for inputting the output of the falling edge detector 3 and the output of the exclusive OR circuit 11 and performing a logical product. The forward traverse of the detector 6 is counted by the counter 7, and this count value is subtracted by the backward traverse of the detector 12.

FIG. 4 is a diagram showing signal waveforms for explaining the operation of the track number crossing control circuit of FIG. As shown in this figure, as a direction in which the optical pickup should move, the RF signal for the movement from the inner circumference to the outer circumference of the disc is set to the forward direction R.
The F signal is used, and the RF signal for the movement in the opposite direction due to the vibration of the player and the eccentricity of the disc is used as the backward RF signal,
F signal is ... Forward RF signal, Reverse RF signal, Reverse R
When the F signal, the forward RF signal, ... Are generated, an on-track signal is formed for each RF signal. A tracking error signal is generated by the comparator 4 for the forward and backward directions of the optical pickup, a track forward crossing signal is generated by the track crossing detector 6, and a track reverse direction crossing signal is generated by the track reverse crossing detector 12. Occur.

In this way, the track reverse crossing number is subtracted from the obtained track forward crossing number by the counter 7, and the subtracted reverse crossing number is caused by the disturbance as described above. It corresponds to the number of tracks that have crossed in the same direction as the optical pickup should move when returning to the original position by the amount of movement. Therefore, by this subtraction, the vibration of the player from the number of crossing tracks in the forward direction,
The number of track crossings due to the eccentricity of the disk can be eliminated. So far, the CD has been explained, but LD, MD
Can be similarly applied to.

[0015]

As described above, according to the present invention, the number of track crossings in only the moving direction of the optical pickup is counted even if there is an influence of vibration of equipment such as a player or an eccentric component of the disc. , The optical pickup can count the number of tracks to move accurately. Further, since the cross-track crossing in the direction opposite to the direction in which the optical pickup should move is detected and the cross-track crossing number in the opposite direction is subtracted from the number of cross-track crossings in the direction in which the optical pickup should move, vibration of equipment such as a player The number of track crossings in the same direction as the moving direction of the optical pickup included in the eccentricity component of the disk or the disk can be removed.

[Brief description of drawings]

FIG. 1 is a diagram showing a degree rack number crossing control circuit in a tracking servo apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing signal waveforms for explaining the operation of the track number crossing control circuit of FIG.

FIG. 3 is a diagram showing a track number crossing control circuit in a tracking servo device according to a second embodiment of the present invention.

FIG. 4 is a diagram showing signal waveforms for explaining the operation of the track number crossing control circuit of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Envelope detector 2, 4 ... Comparator 3 ... Fall detector 5 ... Track crossing direction discriminating unit 6 ... Track crossing detector 7 ... Counter 8 ... Comparator 10 ... Inverter 11 ... Exclusive OR circuit 12 ... Track Reverse crossing detector

Claims (2)

[Claims] 1. A tracking servo device for moving an optical pickup to a target track on a disk, wherein a main signal detected by the optical pickup is envelope-detected, and after the detection, a main pulse signal is formed into an on-track signal of a rectangular pulse. An edge detection circuit (3) for detecting an edge and a track crossing direction of the direction in which the optical pickup should move are determined from tracking error signals having different phases when the optical pickup moves from the inner circumference to the outer circumference or vice versa. A track crossing direction discriminating unit (5) and a track crossing detector (6) for detecting track crossing in a direction in which the optical pickup should move based on the detection edge and the discriminated track crossing direction are provided. When it is counted and reaches a predetermined value, the track is moved. A tracking servo system, characterized by complete. 2. The track reverse direction crossing detector (12) according to claim 1, further comprising a track crossing direction opposite to a direction in which the optical pickup should move.
And the track reverse crossing detector (1) is provided from the number counted by the track crossing detector (6).
2. The tracking servo device according to claim 1, wherein the number of track crossings according to 2) is subtracted.