JPH0785483A - Optical disk controller - Google Patents

Abstract

PURPOSE:To correct an offset and to stably record and reproduce an optical disk by sequentially regulating the offset in response to an offset detection signal before an operation of track control means. CONSTITUTION:A reflected light of an optical disk 5 is made incident on an out-of-focus detector 10 through a diaphragm lens 4, a beam splitter 3, a 1/2 wavelength plate 7, a beam splitter 8 and a cylindrical lens 9. An optical beam from the splitter 8 is input to an out-of-track detector 11. An out-of-focus signal is A/D-converted by an A/D converter 16, and supplied to a digital signal processor 17. The processor 17 compensates a phase of a focus control system, and converges the beam to the disk 5 via an actuator 23. Similarly, an out-of-track signal is made to follow up an information track 6 of the disk 5. Further, the processor 17 detects an offset of a tracking error signal in a state that a tracking control is conducted, and varies an amplification factor of an amplifier 13 to correct the offset.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk control device of an optical recording / reproducing device for recording or reproducing a signal on a record carrier surface by using a converged light beam.

[0002]

2. Description of the Related Art As a technique relating to a device for correcting an offset of a conventional optical disk control device, JP-A-5-128 is known.
Some are described in Japanese Patent No. 565. The operation of the optical disk control device will be described below with reference to the drawings.

The optical disk control device has an optical spot of about 1 μmφ on an information track of 1.6 μm pitch provided on a record carrier of an optical disk in the direction perpendicular to the surface of the record carrier.
Performs highly accurate focus control that follows with 0.5 μm accuracy.

Further, high-precision tracking control is performed in which the track deviation between the information track and the light spot follows with an accuracy of about ± 0.1 μm.

Here, if the control circuit has an offset or the adjustment of the optical head is deviated, highly accurate control cannot be performed.

For example, if the tracking error signal has an offset A as shown in FIG. 2, the control position is displaced by A.

Conventionally, the volume is adjusted to correct this offset.

[0008]

However, in the above configuration, when the circuit offset of the track deviation signal and the adjustment deviation of the optical head change with time or change with temperature, the offset cannot be accurately corrected.

In view of the above problems, the present invention provides an optical disc control device capable of correcting offset and stabilizing recording and reproduction on an optical disc.

[0010]

In order to solve the above problems, the optical disk control device of the present invention comprises a first offset adjusting means for adjusting the offset of the track deviation detecting means and an offset by the track controlling means. A second offset adjusting means, and a first offset adjusting means according to a signal from the offset detecting means before operating the track controlling means.
The offset adjusting means adjusts the offset of the signal of the track detecting means, and the second offset adjusting means is operated after the first offset adjusting.

[0011]

According to the present invention having the above-mentioned structure, the offset of the track deviation detecting means is corrected by the first offset adjusting means, and the signal obtained by correcting the offset of the track deviation signal is used for the track controlling means, and the second offset adjusting means is used. In the track control means, the offset is corrected with the calculation accuracy, the offset is corrected with high accuracy, and the tracking control is performed, and the adjustment is performed when the apparatus is started or when a predetermined time elapses.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical disk control device according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of an optical disk control device according to an embodiment of the present invention.

The light beam emitted from the semiconductor laser 1 is collimated by the collimator lens 2 and focused on the information track 6 of the optical disk 5 through the beam splitter 3 and the diaphragm lens 4. The optical disk 5 is rotated by the motor 12.

Next, the light reflected from the optical disk 5 passes through the aperture lens 4 again to become parallel light, which passes through the beam splitter 3, the half-wave plate 7 and the beam splitter 8,
The focus shift detector 10 enters through the cylindrical lens 9 and constitutes astigmatism type focus shift detection.

The track shift detector 11 constitutes a far-field type track shift detection in which the light beam split by the beam splitter 8 enters.

The signal of each detector is amplified by an amplifier circuit 13,
Amplification or current-voltage conversion is performed at 14, 19, and 20.

The amplified detection signal is obtained by the differential amplifier circuit 15 as a focus shift signal, and the differential amplifier circuit 21 as a track shift signal.

The defocus signal is converted from an analog signal into a digital signal in the AD conversion circuit 16 and enters the digital signal processing circuit 17.

The digital signal processing circuit 17 performs phase compensation processing of the focus control system, and moves the focus actuator 23, which is the focus moving means, via the drive circuit 18 to focus the light beam on the optical disk 5.

Similarly, the track shift signal is converted into a digital signal by the AD conversion circuit 16 and enters the digital signal processing circuit 17 to perform the phase compensation processing of the track control system, and the tracking actuator 24 which is the track moving means.
Is moved to cause the light beam to follow the information track 6 of the optical disk 5.

The digital signal processing circuit 17 detects and stores the offset of the tracking error signal via the AD conversion circuit 16 in a state where the tracking control is not performed.

Further, the offset of the tracking error signal is detected while the tracking control is performed, and the amplification factor of the variable amplification circuit 13 is changed to correct the offset.

In the tracking off state, the waveform as shown in FIG. 2 can be measured, the maximum value B and the minimum value C of the track deviation signal are obtained, and the offset of the track deviation signal is obtained by B-C.

In the tracking-on state, A in FIG. 3 is an offset with respect to the reference level, which is detected by the digital signal processing circuit and added to the data after AD conversion for correction.

The offset correction by the variable amplifier circuit can correct the G offset as shown in F by amplifying the E signal with respect to the D signal as shown in FIG. F indicates DE, and the offset can be corrected by the output of the differential amplifier circuit.

An example of the configuration of the variable amplifier circuit is shown in FIG.
The resistance value of the resistance circuit 25 is switched by the switch circuit 26 to change the amplification factor of the amplification circuit 27.

First, the offset detected by the digital signal processing circuit is corrected by the variable amplification circuit and the differential amplification circuit, and A
The amplitude level of the input signal of the D conversion circuit is secured.

Next, after switching the offset between the variable amplification circuit and the differential amplification circuit, the remaining offset is corrected by the digital signal processing circuit.

In this way, the offset is corrected accurately. The offset correction circuit of the differential amplifier circuit roughly corrects it, and the digital signal processing circuit corrects it with high accuracy, so that it can be accurately corrected without impairing the input range of the tracking signal to the AD conversion circuit.

The circuit scale becomes large in order to improve the correction accuracy only with the configuration in which the amplification factor is switched and the correction is performed as shown in FIG.

Similarly, the offset of the focus shift signal can be corrected with high precision by a simple circuit configuration.

The offset correction is performed by the differential amplifier circuit when the optical disk device is started or when the optical disk is replaced.

The focus operation and the tracking operation are performed when the recording and reproducing operations are not performed, and the offset is corrected by the AD-converted digital signal processing circuit when the recording and reproducing operation is in the standby state.

When the digital signal processing circuit detects the track deviation or the focus deviation, the differential amplifier circuit and the digital signal processing circuit or the digital signal processing circuit performs the detection.

Track out-of-track detection and out-of-focus detection can be detected by a track out-of-focus signal, a focus out-of-focus signal, or the sum of reflected light amounts from the optical disk.

The sum of reflected light amounts can be detected by the track shift detector 11 or the focus shift detector 10.

[0038]

As described above, according to the present invention, the first offset correction circuit, which switches the amplification factor of the differential amplifier circuit to correct the offset, is roughly corrected, and the digital signal processing circuit is accurately corrected. Without damaging the input range of the tracking signal entering the AD conversion circuit with the offset,
Moreover, it is possible to realize an accurate offset correction circuit with a simple circuit configuration.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an optical disk control device according to an embodiment of the present invention.

FIG. 2 is a waveform diagram showing an offset of a tracking deviation signal.

FIG. 3 is a waveform diagram showing an offset of a tracking deviation signal.

FIG. 4 is a waveform diagram for explaining offset correction by an amplifier circuit.

FIG. 5 is a block diagram showing an example of a variable amplifier circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 semiconductor laser 5 optical disk 10 focus shift detector 11 track shift detector 13, 19 variable amplification circuit 15, 21 differential amplification circuit 16 AD conversion circuit 17 digital signal processing circuit 23 focus actuator 24 tracking actuator

Claims (2)

[Claims] 1. A track deviation detecting means for detecting a positional deviation between an information track formed on a record carrier and the light beam, and a track movement for moving a light beam emitted from a light source in a direction substantially perpendicular to the information track. Means, track control means for controlling the track moving means in response to the signal of the track deviation detection means, offset detection means for detecting the offset of the signal of the track detection means, and according to the output of the offset detection means A first offset adjusting means for adjusting an offset of the track deviation detecting means, and a second offset adjusting means for adjusting an offset by the track controlling means are provided, and the offset detecting means before operating the track controlling means. According to the signal of the track offset detection means by the first offset adjusting means. An optical disk control device, wherein the offset of a signal of a stage is adjusted, and the second offset adjusting means is operated after the first offset adjustment. 2. A track deviation detecting means for detecting a positional deviation between an information track formed on a record carrier and the light beam, and a track movement for moving a light beam emitted from a light source in a direction substantially perpendicular to the information track. Means, track control means for controlling the track moving means in response to the signal of the track deviation detection means, offset detection means for detecting the offset of the signal of the track detection means, and according to the output of the offset detection means First offset adjusting means for adjusting the offset of the track deviation detecting means, second offset adjusting means for adjusting the offset by the track control means, and a light beam from the information track is deviated when the track control means is in operation. Is equipped with a track deviation detection means for detecting that At the time of disc replacement or when the track deviation detecting means detects the track deviation, the first offset adjusting means operates the track deviation detecting means in accordance with the signal from the offset detecting means before operating the track controlling means. An optical disk control device, wherein the offset of a signal is adjusted, and when the recording or reproducing process is not performed, the offset detection means is operated to correct the offset by the track control means by the second offset adjustment means.