JPH03212824A - Optical information processor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an optical information processing device that optically records, reproduces, erases, etc. images, audio, code data, etc., and particularly relates to the configuration of a tracking servo circuit. .

[Prior Art] Optical information processing devices are used to record, reproduce, erase, and the like information such as images, audio, and code data on a recording medium using optical means.

Incidentally, optical disk drives used in optical information processing apparatuses are required to be compatible with various recording media, and standards for recording media to ensure compatibility are determined by the ISO.

Here, we will focus only on items related to tracking servo that are directly related to the present invention.

- Taking the case of a write-once optical disc as an example, the standard value of the reflectance R of the recording medium is 10% to 90%, and the standard value of the push-pull tracking error signal amplitude Ip normalized by the amount of reflected light is It is 0.4-0.65. This means a variation in the servo gain of about 19 dB depending on the standard width of the reflectance R.

FIG. 3 shows an example of the configuration of a tracking servo circuit in a boat-based optical disk drive. The signal output from the two-split photodetector 1 becomes a tracking error signal via a differential amplifier 2, and is applied to a tracking coil 6 of an objective lens actuator via an AGc (auto gain control) circuit 8 and a servo circuit 5. Ru. The servo circuit 5 usually includes a phase compensation circuit, a gain amplifier, a power amplifier, and the like. In order to suppress the variation in servo gain due to the difference in reflectance of the recording medium described above, the sum signal of the two-split photodetector 1 corresponding to the amount of reflected light is obtained by the summing amplifier 7, and the gain of the AGC circuit 8 is controlled by the output. control. In other words, the AGC circuit 8
By varying the gain of the servo circuit 5 and keeping the amplitude of the tracking error signal input to the servo circuit 5 constant, fluctuations in the servo gain due to differences in reflectance of the recording medium are suppressed.

[Problems to be Solved by the Invention] However, the conventional configuration has the following problems.

That is, in an actual recording medium, even if the reflectance R is the same, the tracking error signal amplitude rp varies greatly depending on the width and depth of the guide groove provided on the medium.

However, in the configuration as shown in FIG. 3, although it is possible to suppress fluctuations in servo gain due to differences in reflectance R of recording media, it is not possible to suppress fluctuations in servo gain due to differences in tracking error signal amplitude Ip. Therefore, for recording media having the same reflectance R but different tracking error signal amplitudes Ip, the AGC circuit 8 does not work, resulting in a problem in that the servo gain fluctuates.

In order to solve the above problems, the present invention aims to provide an optical information processing device that can suppress fluctuations in servo gain even with differences in tracking error signal amplitude ip of recording media.

[Means for Solving the Problems] In order to achieve the above object, the present invention has the following configuration. That is, the optical information processing device of the present invention is an optical information processing device that optically records, reproduces, erases, etc. information on a recording medium, and includes an amplitude detection circuit that detects the amplitude of a tracking error signal from the recording medium. and a gain control circuit that varies the tracking servo circuit gain in accordance with the output of the amplitude detection circuit to control fluctuations in the servo gain due to differences in tracking error signal amplitude.

The configuration of the present invention preferably includes a light amount detection circuit that detects the amount of light from the recording medium, and an AGC circuit that varies the tracking servo circuit gain in accordance with the output of the light amount detection circuit.

Further, in the configuration of the present invention, it is preferable that the tracking servo circuit gains for different recording media are approximately equal.

[Function] According to the configuration of the present invention described above, an amplitude detection circuit that detects the amplitude of the tracking error signal from the recording medium and a gain control circuit that varies the tracking servo circuit gain according to the output of the amplitude detection circuit are provided. Since the fluctuation of the servo gain due to the difference in the tracking error signal amplitude is controlled, the fluctuation of the servo gain due to the difference in the tracking error signal amplitude ■p of the recording medium is suppressed, and stable tracking servo operation is always realized. I can do it.

Further, as a preferable aspect of the present invention, a light amount detection circuit that detects the amount of light from the recording medium, and an AG that varies the tracking servo circuit gain according to the output of the light amount detection circuit.
Since it is equipped with a C circuit, the AGC circuit cancels out the effects of reflectance differences between recording media and reflectance unevenness within the recording medium, and then only the difference in the tracking error signal amplitude 1p is canceled out by the subsequent gain control circuit. This allows extremely accurate and stable gain control.

Furthermore, as a preferred embodiment of the present invention, the tracking servo circuit gain for different recording media is configured to be approximately equal, so that the signal amplitude manually applied to the servo circuit is approximately equal for all recording media, so that It is possible to achieve highly accurate and stable tracking servo operation using a water circuit.

[Example] An example of the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of an embodiment of the present invention.

In FIG. 1, 1 is a two-split photodetector, 2 is a differential amplifier, 3 is a detection circuit, 4 is a divider, 5 is a servo circuit, 6 is a tracking coil, and 9 is a peak hold circuit.

In the above configuration, the signal from the two-split photodetector 1 becomes the tracking error signal TE via the differential amplifier 2. The amplitude Ta of the tracking error signal TE is detected by a detection circuit 3 which is an example of an amplitude detection circuit.

The detection circuit 3 is a diode detection circuit or the like. Together with the amplitude tracking error signal TE, it is input to the divider 4, which is an example of a gain control circuit. The divider 4 outputs a signal A*TE/Ta, and this output is applied to the tracking coil 6 via the servo circuit 5. Here, A is the gain constant of the divider.

As described above, according to this embodiment, the amplitude Ta of the tracking error signal obtained from the recording medium is directly detected, and the amplitude T
The tracking error signal normalized by a is sent to the servo circuit 5.
Therefore, the amplitude of the tracking error signal input to the servo circuit 5 is always constant, and has the excellent effect that servo gain fluctuations do not occur due to fluctuations in the reflectance R or fluctuations in the tracking error signal amplitude Ip. be.

In the above, since it is easier to detect the amplitude Ta when the tracking servo is off than when the tracking servo is on, the amplitude Ta detected by the detection circuit 3 when the tracking servo is off is held in the peak hold circuit 9 while the servo is on. Continuing to do so is also an effective means.

FIG. 2 shows a second embodiment of the invention.

In this embodiment, the addition amplifier circuit 7 of the first embodiment and the conventional example,
and an AGC circuit 8. The explanation of each individual operation is omitted because it overlaps with that in FIG. 1, but the basic operation is that the conventional AGC circuit 8 absorbs the difference in the reflectance R of the recording medium, and the gain corresponding to the first embodiment is Its feature is that the control circuit absorbs the difference in the tracking error signal amplitude ■p. In this second embodiment, after the AGC circuit 8 cancels out the effects of reflectance differences between recording media and reflectance unevenness within the recording medium,
Since only the difference in the tracking error signal amplitude Ip is absorbed by the subsequent gain control circuit, this has the great advantage that extremely accurate and stable gain control is possible.

According to the embodiments described above, in an optical information processing apparatus that optically records, reproduces, erases, etc. information on a recording medium,
Since it is equipped with an amplitude detection circuit that detects the tracking error signal amplitude from the recording medium and a gain control circuit that varies the tracking servo circuit gain according to the output of the amplitude detection circuit, the reflectance R and the tracking error signal amplitude tp can be different. It was confirmed that this method has an excellent effect of keeping the servo gain constant for various disks.

Here, a detection circuit and a divider are used as examples of the amplitude detection circuit and the gain control circuit, respectively, but the circuit configuration is not limited to this. For example, when configured with a digital circuit, an A/D converter, It is also possible to apply a peak detection circuit, a D/A converter, a variable gain amplifier, etc.

[Effects of the Invention] As is clear from the above description, the optical information processing device of the present invention is an optical information processing device that optically records, reproduces, erases, etc. information on a recording medium. Since it is equipped with an amplitude detection circuit that detects the tracking error signal amplitude and a gain control circuit that varies the tracking servo circuit gain according to the output of the amplitude detection circuit, the servo gain is controlled by the difference in the tracking error signal amplitude Ip of the recording medium. It is possible to achieve the remarkable effect of suppressing fluctuations in the tracking servo and always realizing stable tracking servo operation.

According to a preferred aspect of the present invention, there is also provided a light amount detection circuit that detects the amount of light from the recording medium, and a tracking servo circuit that varies the gain of the tracking servo circuit according to the output of the light amount detection circuit.
Since it is equipped with a GC circuit, the AGC circuit cancels out the effects of reflectance differences between recording media and reflectance unevenness within the recording medium, and then only the difference in the tracking error signal amplitude Ip is canceled out by the subsequent gain control circuit. As a result, it is possible to achieve the effect of enabling highly accurate and stable gain control.

Furthermore, according to another preferred aspect of the present invention, since the tracking servo circuit gains for different recording media are configured to be approximately equal, the signal amplitudes input to the servo circuit are approximately equal for all recording media. The effect of realizing highly accurate and stable tracking servo operation with a servo circuit having a small dynamic range can be achieved.

[Brief explanation of drawings]

FIG. 1 is a configuration circuit diagram of an optical information processing device according to a first embodiment of the present invention, FIG. 2 is a configuration circuit diagram of a second embodiment of the invention, and FIG. 3 is a configuration circuit diagram of a conventional optical information processing device. It is a circuit diagram. 1...2-split photodetector, 2...Differential amplifier, 3...
・Detection circuit, 4...Divider, 5...Servo circuit,
6...Tracking coil, 7...Summing amplifier, 8
...AGC circuit, 9...Peak hold circuit.

Claims (3)

[Claims] (1) An optical information processing device that optically records, reproduces, erases, etc. information on a recording medium, which includes an amplitude detection circuit that detects the amplitude of a tracking error signal from the recording medium, and an amplitude detection circuit that detects a tracking error signal amplitude from the recording medium. What is claimed is: 1. An optical information processing device comprising: a gain control circuit that varies a tracking servo circuit gain according to output; and controls fluctuations in servo gain due to differences in tracking error signal amplitude. (2) a light amount detection circuit that detects the amount of light from the recording medium;
Auto gain control (AGC) that varies the tracking servo circuit gain according to the output of the light amount detection circuit
2. The optical information processing device according to claim 1, further comprising: a.) circuit. (3) The optical information processing apparatus according to claim 1 or 2, wherein the tracking servo circuit gains for different recording media are substantially equal.