KR100263586B1 - Automatic adjust apparatus for tracking error offset - Google Patents

Abstract

PURPOSE: A device for adjusting a tracking error offset is provided to automatically adjust difference in zero points for a mechanical tracking error and an electric tracking error by using a tracking error value. CONSTITUTION: A tracking error detect unit(1) detects a tracking error through non-invert amplifies a difference in electric signals from first and second photodiodes(PD1,PD2). An amplify unit(2) amplifies the signal from the detect unit for applying to a tracking actuator. An A/D(Analog/Digital) convert unit(3) converts the signal from the detect unit into digital. A microcomputer(5) automatically adjust tracking error offset by using a signal from a key input unit(4) after storing a symmetric value centering upon a ground in an EEPROM(7). A D/A(Digital/Analog) convert unit(6) converts the digital signal from the microcomputer into analog. Thus, the convert unit adjusts an electric signal received in the second photo diode.

Description

Tracking Error Offset Automatic Adjustment

1 is a general tracking error detection circuit diagram.

FIG. 2 shows the relationship between the output of FIG. 1 and the position of the main beam on the track. FIG.

3 is a schematic configuration diagram of a conventional tracking error offset adjusting device.

(A) of FIG. 4 is an output waveform diagram before adjustment of FIG.

(b) is an output waveform diagram after adjustment of FIG.

5 is a tracking error offset automatic adjustment device of the present invention.

6 is a flow chart according to the description of FIG.

* Explanation of symbols for main parts of the drawings

1: Tracking Error Detection Unit 3: Analog / Digital Converter

4: keypad 5: micom

6: digital / analog converter 7: Y pyrom

The present invention relates to a device for automatically adjusting a tracking error offset, and in particular, in an optical disk system, to automatically adjust a difference between a zero point of an optical and mechanical tracking error and a zero point of an electrical tracking error by using a tracking error value. Tracking error offset automatic adjustment device.

Typical optical disc systems require the laser beam to trace the track on which the information is stored on the disc in order to accurately read the information on the disc with the laser beam.

In order to achieve the tracking control purpose, two photodiodes (port diodes PD1 and PD2) shown in FIG. 1 can sense the reflected light when the laser beam does not pass vertically to the left and right of the track fit. Control so that the difference PD1-PD2 of the electrical signal output from PD1) PD2 becomes zero.

2 shows the relationship between the tracking error detection values PD1-PD2 and the position of the main beam on the track. If the tracking error detection value is a positive value, the main beam is on the left side of the track. If the tracking error detection value PD1-PD2 is negative, the main beam is located on the right side of the track.

However, the zero point of the electrical tracking error that is the tracking control target and the point where the actual laser beam traces on the track fit of the disc do not exactly match due to errors in the optical, mechanical, or electrical tracking error generating elements.

The conventional tracking error offset adjustment device tracks a tracking error by non-inverting and amplifying the difference between the electrical signals received and converted by the first and second photodiodes PD1 and PD2 as shown in FIG. And a variable resistor VR1 for adjusting a difference between the zero point of the tracking error output from the tracking error detector 100 and the zero point of the optical and mechanical tracking error in accordance with the external control signal. Lose.

Referring to the operation of the conventional tracking error offset adjustment device configured as described above, when the pickup projects a laser beam on the track feet on the disc, the first and second photodiodes PD1 and PD2 detect light reflected from the track pit on the disc. To be converted into an electrical signal, and the electrical signal converted by the first photodiode PD1 is applied to the non-inverting terminal (+) of the amplifier OP through the resistor R1 of the tracking error detecting unit 100. The electrical signal converted by the second photodiode PD2 is sequentially applied to the inverting terminal (-) of the amplifier OP through the resistor R2 and the capacitor C1 of the tracking error detector 100.

Accordingly, the tracking error detector 100 amplifies the difference between the electrical signals converted and output from the first and second photodiodes PD1 and PD2 to a predetermined level, as shown in FIG. Similarly, the tracking error signal PD1-PD2 is detected.

On the other hand, the zero point of the tracking error signal TE and the point where the actual laser beam traces on the track fit are not exactly matched by optical, mechanical, or electrical tracking error generating elements. Tracking error offset (TED) is generated as shown in FIG.

The voltage adjusted by the variable resistor VR1 to adjust the tracking error offset TED generated in this manner is divided by the resistors R3 and R4 of the tracking error detection unit 100 to invert the terminal OP of the amplifier OP. The position of the zero point of the actual optical and mechanical tracking error coincides with the position of the zero point of the electrical tracking error as shown in (b) of FIG.

However, such a conventional tracking error offset adjustment device has a problem in that a lot of time and manpower is required for tracking error offset adjustment due to the large number of adjustment terminals.

Accordingly, an object of the present invention is to provide a tracking error offset automatic adjustment device for automatically adjusting a difference between a zero point of an optical and mechanical tracking error and an electrical tracking error in an MLP system using a tracking error value. have.

The object of the present invention is a tracking error detection unit for detecting a tracking error by non-inverting the difference between respective electrical signals received and converted by the first and second photodiodes, and digitally converting a signal output from the tracking error detection unit. The analog / digital converter which converts the output signal to the output signal and the tracking error offset value increased by the signal output from the analog / digital converter are stored in EPI, and then the tracking error according to the external control signal. And a digital / analog converter for converting a digital signal output from the microcomputer into an analog signal and adjusting an electrical signal received and converted by a second photodiode. The permanent reference to the accompanying drawings as follows.

5 is an automatic adjustment device for tracking error offset according to the present invention. As shown therein, non-inverted amplification of the difference between the electrical signals received and converted by the first and second photodiodes PD1 and PD2 is used for tracking. A tracking error detection unit 1 for detecting an error, an amplification unit 2 for amplifying a signal output from the tracking error detection unit 1 to a predetermined level, and applying it to a tracking actuator TA, and the tracking error detection unit The analog / digital converter 3 converts and outputs the signal output from (1) into a digital signal, and the ground among tracking error offset values increased by the signal output from the analog / digital converter 3; The microcomputer 5 stores the symmetric value in the YPIROM 7 and automatically adjusts the tracking error offset by the signal output from the key input unit 4, and the digital signal output from the microcomputer 5. Is converted into an analog signal and configured as a digital / analog converter 6 for adjusting an electrical signal received and converted by the second photodiode PD2.

When the user presses the key of the key input unit 4 to adjust the tracking error offset, the microcomputer 5 moves from the key input unit 4 to the present invention. When the control signal is output after recognizing the output signal, the tracking servo off switch SW1 of the tracking error detection unit 1 is turned off.

In addition, the microcomputer 5 applies a minimum tracking error offset value to the digital / analog converter 6, and the digital / analog converter 6 transmits the value output from the microcomputer 5 through the resistor R5. The tracking error detector 1 is applied to the inverting terminal (-) of the amplifier.

As the tracking servo off switch SW1 is turned off, the amplifier OP of the tracking error detection unit 1 receives an electrical signal received and converted by the first photodiode PD1 through a non-inverting terminal (R1). The electrical signal received by the second photodiode PD2 adjusted by the signal output from the digital / analog converter 6 and converted by +) and converted through the resistors R2 and R3. It is applied to (-) and the difference is non-inverted and the tracking error is detected.

The tracking error signal detected by the tracking error detector 1 is converted into a digital signal through the analog / digital converter 3 and applied to the microcomputer 5.

Accordingly, the microcomputer 5 recognizes the signal output from the analog / digital converter 3 and determines whether the recognized value is symmetrical with respect to the ground. If the tracking error value outputted from the analog / digital converter 3 is symmetric about the ground, it is stored in the EPIROM 7 when the analog converter 6 is repeatedly applied to the analog converter 6. Let's do it.

Thereafter, when the user presses the key of the key input unit 4, the microcomputer 5 extracts the tracking error offset adjustment value stored in the ypyrom 7, and then through the digital / analog 7 converting unit 6, the tracking error detecting unit 1 ) So that the tracking error offset is automatically adjusted.

The present invention described above has the effect of adjusting the tracking error offset within a short time by automatically adjusting the optimum point of the tracking error offset by receiving the tracking error value.

Claims (1)

Tracking error detecting means for detecting a tracking error by non-inverting and amplifying the difference between the electrical signals received and converted by the first and second photodiodes, and converting the analog signal output from the tracking error detecting means into a digital signal. Among the analog / digital converting means to output and the tracking error offset value increased by the signal output from the analog / digital converting means, the symmetrical ground is stored in EPIROM and the tracking error offset is automatically adjusted according to the external control signal. And a digital / analog converting means for converting a digital signal output from the microcomputer into an analog signal to adjust an electrical signal received and converted by the second photodiode. Adjuster.