JPH0634318B2 - Disk servo device - Google Patents

Description

The present invention relates to a disc servo device used in a disc reproducing device for reading information recorded on a recording medium such as a compact disc.

[Prior Art] A disc reproducing apparatus for reproducing music information recorded on a recording medium such as a compact disc (CD) is shown in FIG. A disk servo device for focusing the light 4 is installed. The CD 2 is rotated at a constant linear velocity by the motor 6 controlled by the _linear velocity control signal D _CLV . A laser beam 4 generated by a laser beam 10 from a pickup 8 is radiated to the track surface of the CD 2 through an optical system including a half mirror 12 and an objective lens 14 in a beam shape, and reflected light 16 from the track surface 16 is reflected. Is reflected by the half mirror 12 and converted into an electric signal by the light receiving portion 18 including a light receiving element. In this case, the focus of the laser beam 4 is adjusted by changing the focus position of the objective lens 14 of the optical system by driving the focus coil 20 by the focus drive signal FD, and the movement of the focus position onto the track is The tracking coil 22 is driven by the tracking drive signal TD.

Then, the detection signal Vi based on the reflected light 16 obtained by the light receiving unit 18 is added to the tracking error detection circuit 26 provided in the tracking servo loop 24 to detect the tracking error. The tracking error signal TE representing the tracking error output from the tracking error detection circuit 26 is applied to the zero cross detection circuit 28 for detecting the zero cross point. The zero-cross detection circuit 28 uses the tracking error signal TE
And a zero-cross signal TZC representing the zero-cross point by comparison with the zero level. This zero-cross signal TZC is added to the track jump control unit 30 which is a track jump control means, and is used for detection of an appropriate track position and track jump control.

The track jump control unit 30 generates a track jump signal according to the track jump command signal JP. This track jump signal is added to the tracking driver 32 that generates the drive signal TD for driving the tracking coil 22 together with the tracking error signal TE, and becomes the basis of the drive output.

The tracking driver 32 uses the tracking error signal TE from the tracking error detection circuit 26, or
The drive signal TD is generated according to the track jump signal from the track jump control unit 30, and the tracking coil 2
Drive 2 As a result, the tracking coil 22 is excited, and the focus of the laser beam 4 is operated on the proper track or the track position of the CD 2 to be moved.

[Problems to be solved by the invention]

By the way, the tracking control is performed by applying the tracking error signal TE generated by the tracking error detection circuit 26 to the tracking driver 32, and by the drive signal TD based on the tracking error signal TE. The tracking control is performed not only in the initial state when the power is turned on, but also in the normal reproduction.
Therefore, the tracking driver 32 works so as to follow the spot center, and the tracking error signal TE is constantly changing.

When a track recorded on the CD 2 is moved to a specific track (track jump), such as when cuing the track, jump control is performed through the track jump control unit 30 when the track jump command signal JP arrives. Is done. In that case, in the track jump, the necessary number of tracks is detected by counting the zero-cross signals TZC obtained by the zero-cross detection circuit 28 based on the tracking error signal TE.

The zero-cross signal TZC is used for track jumping and is not necessary at the time of reproduction, but the zero-cross detection circuit 28 operates even at the time of reproduction, so that the zero-cross signal TZC is output. Then, the tracking error detection circuit 26 generates the tracking error signal TE close to 0 V even during the normal reproducing operation, and the zero-cross detection circuit 28 detects the zero-cross point of the tracking error signal TE and outputs the zero-cross signal TZC. Of. Since this zero-cross signal TZC is a pulse signal (switching signal) that switches according to the zero-cross point, it has a sharp level change, which adversely affects the servo loop as high-frequency noise during normal reproduction, and This causes the operation to malfunction.

Therefore, the present invention suppresses the generation of the zero-cross signal TZC other than during the track jump period.

[Means for solving problems]

As shown in FIG. 1, the disk servo apparatus of the present invention, when a track jump is performed, a track jump control signal TJ
A track jump control means (track jump control unit 38) for generating a signal Cj and a signal Tj representing a track jump period, and a zero cross point of the tracking error signal TE are detected, and the operation can be arbitrarily switched. A signal T that is constructed and represents the track jump period.
A zero-cross detection circuit 34 that operates during the track jump period according to j and stops the operation during normal reproduction.

[Work]

In the disk servo device of the present invention, the operation of the zero-cross detection circuit 34 is stopped during a period other than the track jump period (during normal reproduction), and the zero-cross signal TZC is generated only during the track jump period. The effect on the servo system is avoided.

〔Example〕

FIG. 1 shows an embodiment of the disk servo device of the present invention.

The zero-cross detection circuit 34 is configured to detect a zero-cross point of the tracking error signal TE from the tracking error detection circuit 26 and to switch its operation arbitrarily from the outside. For example, the zero-cross detection circuit 34 is configured by a comparator having a zero-cross point level set. It The switch 36 is an operation switching means including a transistor for cutting off the supply of the operating current to the zero-cross detection circuit 34 and switching its operation, and can be configured as an internal circuit or an external circuit of the zero-cross detection circuit 34.

Further, the track jump control unit 38 installed as a track jump control means generates a tracking control signal TC in response to the zero cross signal TZC, and also independently generates a track jump control signal TJC by a track jump command signal JP. At the same time, the interlace period signal Tj representing the track interlace period is generated.

Therefore, the jump period signal Tj is used as an operation switching signal of the zero-cross detection circuit 34 to close the switch 36 during the jump period, thereby selectively operating the zero-cross detection circuit 34 only during the track jump period.

By doing so, the zero-cross detection circuit 34 operates during the track jump period to generate the zero-cross signal TZC, and the zero-cross signal TZC does not occur even if the tracking error signal TE arrives during normal reproduction. Therefore, during the track jump period, the track jump control signal by the zero cross signal TZC can be used to transfer to an arbitrary track in response to the arrival of the track jump command signal JP, and the generation of the zero cross signal TZC is stopped during normal reproduction. , The influence of the zero-cross signal TZC on the reproducing operation is avoided.

〔The invention's effect〕

According to the present invention, the operation of the zero-cross detection circuit is performed only during the track jump period, and the generation of the zero-cross signal is canceled during the normal reproduction, so that the influence on the reproduction operation of the zero-cross signal can be avoided, and the proper data reproduction can be performed. It can be carried out.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a disk servo device of the present invention, and FIG. 2 is a block diagram showing a general disk servo device. 34: Zero-cross detection circuit 38: Track jump control section (track jump control means)

Claims (1)

[Claims] 1. A track jump control means for generating a track jump control signal at the time of a track jump, and a signal for indicating a track jump period, and a zero-cross point of a tracking error signal are detected. A disk servo device having a zero-cross detection circuit which is configured to be switchable in operation and which operates during a track jump period according to a signal indicating the track jump period and stops the operation during normal reproduction.