KR950003177B1 - Tilting offset auto controller - Google Patents

Abstract

The device comprises a detector(1) for detecting tracking error according to the light emitting voltage of LED(light emitting diode), a micom(4) for scanning the output value of the detector(1) to store maximum tracking error in a memory section(5) and output tilt offset control signal, a D/A converter for converting digital tilt offset signals into analog signal, and a tilt off set controller for controlling tilt offset according to output value of D/A converter.

Description

Tilt offset automatic adjuster

1 is a schematic configuration diagram of a general MLP system.

2 is a diagram showing the relationship between the disk tilt and the light receiving element of FIG.

3 is a circuit diagram of a tilt servo meter for adjusting a conventional tilt offset.

4 is a voltage waveform diagram before and after adjusting a conventional tilt error.

5 is a circuit diagram of the tilt offset automatic adjustment device of the present invention.

6 is a flowchart for explaining the microcomputer operation of FIG.

* Explanation of symbols for main parts of the drawings

1: Tracking Error Detection Unit 4: Micom

5 memory unit 6 D / A conversion unit

7: tilt error adjusting unit 8: detailed description of the invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tilt offset automatic adjustment device in a MLP system. In particular, the tilt offset is caused by a difference between a zero point of an optical and mechanical tilt error and a zero point of an electrical error. The present invention relates to a tilt offset automatic adjustment device which digitally adjusts an externally adjusted by using a variable volume and uses an amplitude magnitude of a tracking error.

In general, the tilt control in the MLP system ensures that the recording surface on which the disk information is recorded and the laser beam reading the data are exactly perpendicular in order to accurately read the information recorded on the disk surface by the laser light.

The tilt control has two photodetectors capable of judging the inclination of the disk and controls the difference between the detections of the two photodetectors to be zero.

At this time, the zero point of the electric tilt error that is the tilt control target and the position where the laser beam is perpendicular to the information plane of the disk do not exactly match due to optical errors, mechanical errors, and errors of the electric tilt error generating elements.

Therefore, in order to solve this problem, by attaching a variable resistor that can adjust the offset of the tilt error to the outside to maximize the tracking error amplitude, the position where the beam becomes vertical and the position where the tilt error becomes zero Have been matched.

1 is a schematic configuration diagram of a general MLP system, including a pickup assembly 101 for emitting light onto a disc 100 and converting light reflected from the disc 100 into an electrical signal corresponding thereto; And a spindle motor 102 for moving the 1010.

Reference numeral 103 denotes a clamper, and PD3 and PD4 denote light-emitting diodes.

Referring to the operation of the MLP system configured as described above, in order to generate a tilt error, laser light is emitted from the light emitting diodes PD1 and PD2 in the pickup assembly 101 to the disk 100.

The laser light reflected by the disk 100 is received by the light receiving diodes PD3 and PD4, and the amount of received light varies according to the inclination of the disk 100.

Therefore, the amount of light received by each of the light receiving diodes PD3 and PD4 is converted into an electrical signal, and then PD3-PD4 is obtained.

The laser beam emitted from the light emitting diodes PD1 and PD2 in the pickup assembly 101 is controlled by controlling the pickup assembly 101 so that the value obtained by PD3-PD4 is used as the tilt error value and the tilt error value is zero. The disk 100 is perpendicular to the disk 100.

In the case of the tilt control, the position where the value of PD3-PD4 becomes "0" and the position where the laser beam is perpendicular to the disk information surface are not exactly matched by mechanical errors. Turn off the tracking servo.

After that, the variable resistance VR2 is adjusted to maximize the tracking error amplitude.

When the tracking servo is turned off, the tracking error can be observed because the laser beam crosses the track due to the eccentricity of the disc itself.

In more detail, as shown in FIG. 3, the electrical signal corresponding to the light output from the light emitting diode PD1 in the pickup assembly 101 is applied to the non-inverting terminal of the amplifier op1 in the tracking error detector 104. Is entered in +). In addition, the electrical signal corresponding to the light output from the light emitting diode PD2 is controlled by the variable resistor VR2 after being passed through the resistor R6 and input to the inverting terminal (-) of the amplifier OP1.

Accordingly, the amplifier OP1 obtains a difference between voltages input to the two terminals + and −, and then amplifies the secondary value and inputs it to the subtraction unit 106.

In addition, the voltage value corresponding to the light received by the photodiode PD3 of the pickup assembly 101 is input to the non-inverting terminal (+) of the amplifier OP2 through the resistor R1 in the tilt error detector 105.

Similarly, the voltage value corresponding to the light received by the photodiode PD4 of the pickup assembly 101 is charged and discharged through the resistor R2 and then discharged and discharged in the capacitor C1, and the voltage discharged in the capacitor C1 is a variable resistor ( VR1) is input to the inverting terminal (-) of the amplifier OP2.

Accordingly, the amplifier OP2 obtains the difference between the voltages input to the two terminals (+,-), amplifies the difference value, and inputs the difference to the subtraction unit 106.

4A and 4B are waveform diagrams showing changes in amplitude before and after adjusting the tilt error with the variable resistor VR1.

Accordingly, the subtractor 106 subtracts the values output from the tracking error detector 104 and the tilt error detector 105, respectively, and inputs the resultant values to the amplifier 107.

The amplifier 107 amplifies the input value to a predetermined level and applies the tilt motor 108 to the tilt motor 108 to move the pickup assembly 101 by the input value to correct the tilt error.

However, in the conventional MLP system, unlike the other AV systems, the tilt error correction device has a large number of adjustments for adjusting tracking errors, tilt errors, etc., and there is a problem in mass production, and the adjustment volume may change due to a user's shock or mistake. There was a problem that many do not play or the playback quality is reduced.

Accordingly, an object of the present invention is to provide a tilt offset automatic adjustment device for digitally adjusting the tilt offset caused by the difference between the zero point of the optical and mechanical tilt error and the zero point of the electrical error by using the amplitude of the tracking error. .

The object of the present invention is to search for a digitally converted tracking error value, to find a maximum value of the tracking error among the searched value to output a tilt offset adjustment signal, and a memory for storing the tracking error data obtained from the micom And a digital / analog converter for converting the digital adjustment signal obtained from the microcomputer into an analog signal, which will be described below in detail with reference to the accompanying drawings.

5 is a circuit diagram of the tilt offset automatic adjustment device according to the present invention, in which a tracking error detection unit 1 detects a tracking error in accordance with the light emission voltages of the light emitting diodes PD1 and PD2 in the pickup assembly, and in the tracking error detection unit 1; After receiving the obtained value to the input terminal (A / D) and searching for the received signal, the tracking error is maximized to find the maximum value (4) and the data obtained from the microcomputer (4) to automatically adjust the tilt offset. Obtained by the digital / analog converter (6) and the memory unit (5) for storing the first, the digital offset controller (6) for converting the tilt offset adjustment signal outputted from the A tilt offset adjustment unit 7 for adjusting the tilt offset according to a value, a second amplifier 8 for amplifying and outputting a signal output from the tilt offset adjustment unit 7 by a predetermined level, and the second amplifier 8 According to the value obtained in Is composed of a tilt motor 9 for moving the pickup combination (the figure did not shown).

Referring to Figure 6 attached to the operation and effects of the present invention the tilt offset automatic adjustment device configured as described above in detail as follows.

After playing with the Playkey from the outside, the tracking servo is turned off after a predetermined time.

Then, the electrical signals corresponding to the amount of light emitted from the light emitting diodes PD1 and PD2 in the pick-up assembly (not shown) are respectively passed through the resistors R1 and R2 in the tracking error detection unit 1 through the amplifier OP1. ) Input to non-inverting terminal (+) and inverting terminal (-) respectively.

The amplifier OP1 obtains a voltage value input to the two terminals (+,-), amplifies the difference value by a predetermined level, and inputs the input terminal A / D and the first amplifier 2 of the microcomputer 4, respectively. Enter it. The first amplifier 2 amplifies this input value to a predetermined level and applies it to the tracking actuator 3.

In addition, when the microcomputer 4 receives a digital value according to a tracking error input through the input terminal A / D, the microcomputer 4 outputs a control signal through the port P1, and the control signal is converted into a D / A converter 6. Is converted into an analog value and input to the tilt offset adjustment unit 7.

Accordingly, the inverting terminal (-) input value in the tilt offset adjustment unit 7 is changed, and thus the output value of the amplifier OP2 is changed and output.

The value output from the tilt offset adjuster 7 is amplified to a predetermined level through the second amplifier 8 and then applied to the tilt motor 9 so that the pickup assembly moves left and right. As the pickup assembly moves, the output value of the tracking error detection unit 1 changes, and thus the value input to the input terminal A / D of the microcomputer 4 also changes correspondingly.

In this way, the microcomputer 4 continuously outputs the control signal to the port P1, and the tracking error value is continuously changed accordingly.

The microcomputer 4 continuously searches for the peak-to-peak value of the tracking error that is changed in this way, finds the tilt offset value at which the tracking error is maximum, and stores it in the memory unit 5.

In this way, if play is inputted from the outside after storing the value at which the tracking error is maximum, the microcomputer 4 outputs the value stored above as a control signal through the port P1 so that play is performed in the state where the offset is adjusted. It is to be done.

If the tilt offset is biased too much during the tilt offset adjustment, the focusing is not performed. Therefore, the microcomputer 4 increases the tracking error until focusing is performed so that the tilt offset increases. As described in detail above, the present invention has the effect of being able to adjust the tilt offset within a faster time than manual adjustment because it can be automatically adjusted using a microcomputer.

In addition, since the tilt offset adjustment is adjustable in the microcomputer itself, not in the manual organization, there is an effect that no measurement equipment such as an oscilloscope is needed, and since the adjustment volume does not change, the reproduction can always obtain a clear reproduction quality. There is also.

Claims (2)

A tracking error detecting means for detecting a tracking error according to the light emitting diode light emitting voltage in the pickup assembly, a value obtained by the tracking error detecting means, and searching for a value at which the tracking error becomes the maximum among the searched values and storing it in the memory unit And a tilt offset adjustment according to a value obtained from the digital / analog conversion means, and a microcomputer for outputting a tilt offset adjustment signal, a digital / analog conversion means for converting the digital tilt offset adjustment signal output from the micom to an analog signal. Tilt offset adjustment device characterized in that it comprises a tilt offset adjustment means. 2. The tilt offset adjusting means according to claim 1, wherein the tilt offset adjusting means determines a difference value between a voltage value received from the first light receiving element, a voltage value received from the second light receiving element and a voltage value obtained by subtracting the voltage value obtained from the D / A converting means. A tilt offset adjustment device characterized in that amplified by a predetermined level and output as a tilt offset adjustment value.