KR19980040689A - Defect Compensation Circuit of Optical Disc Data Reproduction System - Google Patents

Abstract

A defect compensation circuit of an optical disc data reproducing system is disclosed. A photodetector that converts and outputs an optical signal containing data into an electrical signal, outputs a track error detector that detects the amount of tracking error by inputting an electrical signal, and a tracking servo that controls the tracking motor in accordance with the amount of tracking error. This circuit used in an optical disk data reproducing system includes defect delay means for inputting a defect signal, delaying and outputting the defect signal in response to the system clock by the size of the defect signal, and tracking error amount. Low pass filter input and low pass filtering to output the low pass filtered tracking error amount to the tracking servo and the output of the tracking error amount selectively output to the tracking servo or low pass filter in response to the output of the defect delay means Means for stabilizing by delaying the defect signal. And, there is an effect that allows to reduce the level to be quickly track the tracking than a zoom.

Description

Defect Compensation Circuit of Optical Disc Data Reproduction System

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk data reproducing system such as a compact disk player (CDP) or the like, and more particularly to a defect compensation circuit used in a circuit such as a CDP.

In the conventional compact disc player circuit, an unstable condition due to focus error and tracking error caused by reading data in a transitional state in which a defect waveform is not completely stable occurs, and a phenomenon of leaving the track occurs.

An object of the present invention is to provide a defect compensation circuit for compensating a defect signal to improve a track following function.

1 is a view for explaining a block diagram of a defect compensation circuit according to the present invention.

2 (a) to 2 (e) are waveform diagrams of respective parts shown in FIG.

3 is a circuit diagram of one preferred embodiment of the present invention of the circuit shown in FIG.

In order to achieve the above object, an optical detector for converting and outputting an optical signal containing data into an electrical signal, a track error detection unit for inputting the electrical signal to detect a tracking error amount, and corresponding to the tracking error amount A defect compensation circuit according to the present invention used in an optical disk data reproducing system including a tracking servo for controlling a tracking motor, inputs a defect signal and responds to the system clock by a magnitude of the defect signal. Defect delay means for delaying and outputting a signal, a low pass filter for inputting a tracking error amount, and a low pass filter for outputting the low pass filtered tracking error amount to the tracking servo and the output of the tracking error amount. The tracking servo or the low pass in response to the output of the effect delay means Is composed of a selection means for selectively outputting teoro preferred.

Hereinafter, the configuration and operation of the defect compensation circuit according to the present invention will be described with reference to the accompanying drawings.

1 is a block diagram of a defect compensation circuit according to the present invention, and includes a track error detector 10, a tracking servo 20, and a defect delay unit constituting the defect compensation circuit according to the present invention. 30), a switch 32 and a low pass filter (LPF) 34.

The track error detector 10 shown in FIG. 1 detects a tracking error amount by inputting an electrical data signal from an optical detector (not shown) through an input terminal IN1 and outputs the detected tracking error amount to a switch 32. do. Here, the light detector irradiates light onto the disk, reflects the light from the disk, and converts an optical signal including data into an electrical signal and outputs the converted electrical signal.

2 (a) to 2 (e) are waveform diagrams of the respective parts shown in FIG. 1, FIG. 2 (a) is a radio frequency signal, FIG. 2 (b) is a defect signal, and FIG. (c) shows the tracking error in the normal mode, FIG. 2 (d) shows the tracking error signal passing through the low pass filter, and FIG. 2 (e) shows the waveform diagrams of the signal output from the defect delay unit 30. FIG. Indicates.

The defect delay unit 30 inputs the defect signal shown in FIG. 2B extracted from the radio frequency signal shown in FIG. 2A through the input terminal IN2 shown in FIG. The input defect signal is delayed by the pulse width of the defect signal in response to the system clock CK and output to the switch 32.

When the tracking error is in the normal mode, it takes time to follow the track because the level of the tracking error is large, but sometimes the track is out of track. Therefore, to compensate for this, the defect delay unit 30 inputs and delays the defect signal, and outputs the delayed signal shown in FIG. 2E to the switch 32.

On the other hand, the switch 32 selectively outputs the signal output from the track error detector 10 to the tracking servo 20 or the LPF 34 in response to the delayed defect signal output from the defect delay unit 30. . If a defect signal is generated, the tracking error amount output from the track error detector 10 is output to the LPF 34 in response to the signal generated by the defect delay unit 30. The LPF 34 inputs the tracking error amount shown in (c) of FIG. 2 having a large level to filter the low frequency component, and outputs the tracking error amount to which the low frequency component is filtered to reduce the level to the tracking servo 20. .

However, when no defect signal is generated, the tracking error amount output from the track error detection unit 10 is output to the tracking servo 20.

The tracking servo 20 inputs a tracking error amount or an output of the low pass filter 34 to output a control signal for controlling the tracking servo to the driving integrated circuit through the output terminal OUT1.

FIG. 3 is a circuit diagram of a preferred embodiment of the present invention of the circuit shown in FIG. 2, consisting of two multiplexers, nine flip-flops, and a plurality of logic gates.

The circuit shown in FIG. 3 delays the defect signal in response to the system clock CK by the pulse width of the defect signal input through the input terminal IN2 and outputs the signal shown in FIG. 2E through the output terminal OUT2. This function outputs the defect signal. Here, the reset signal RESET is a signal for resetting the device shown in FIG.

As described above, the defect compensation circuit according to the present invention has an effect of allowing the track to be followed more quickly by delaying and stabilizing the defect signal and reducing its level.

Claims (1)

Optical detector converts and outputs an optical signal including data into an electrical signal, a track error detector for detecting the amount of tracking error by inputting the electrical signal, and a tracking motor to control the tracking motor in accordance with the amount of the tracking error. In a defect compensation circuit used in an optical disk data reproducing system including a servo, Defect delay means for inputting a defect signal and delaying and outputting the defect signal in response to a system clock by the magnitude of the defect signal; A low pass filter for inputting a tracking error amount to perform low pass filtering, and outputting the low pass filtered tracking error amount to the tracking servo; And And means for selectively outputting the output of the tracking error amount to the tracking servo or the low pass filter in response to the output of the defect delay means.