JPH09161301A - Optical information reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reproduce information at the most suitable laser power value by reproducing the information recorded on other area with laser light irradiated with a drive signal of a laser element based on a signal level held by a level setting means. SOLUTION: CPU 13 varies the output value of a D/A converter 14, and varies a drive current of an LD driver 7 so as to obtain a prescribed pulse height value and makes a laser diode 5 emit light with a reproducing power value. Then, when the pulse height value of a regenerative signal becomes the prescribed pulse height value (Yes), the pulse height value is set and held (step S7). After being set in the pulse height value, the data are reproduced. In such a manner, the data are reproduced by controlling the reproducing laser power.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information reproducing apparatus for reproducing information from an optical recording medium such as a magneto-optical disk.

[0002]

2. Description of the Related Art FIG. 6 shows the structure of a reproduction signal processing system in a general optical information reproducing apparatus. This reproduction signal processing system includes a detector 20 that detects a signal recorded as information from an optical recording medium, an amplifier 21 that amplifies the detected signal, and a noise filter 22 that cuts noise in an unnecessary signal band. , A binarization circuit 23 for binarizing the reproduction signal
A PLL circuit 24 for generating a synchronous clock, a discriminator 25 for discriminating whether or not data exists in a detection window obtained by the synchronous clock, and a decoder 26 for decoding encoded record data. It is composed of.

The amplifier 21 is generally AGC (Aut).
o Gain Control), which causes variations in the amplitude of the detection signal that can occur due to various factors such as variations in recording sensitivity of optical recording media, changes in environmental conditions such as temperature, dirt and scratches on the media, and changes over time. The value of the input signal is corrected so as not to be too large or too small so that the noise filter and the binarization circuit can operate normally. Usually this A
The GC circuit includes a multiplier, a rectifier circuit, a differential amplifier, and a constant voltage power source, and the output level range is determined by the voltage of the constant voltage source.

However, if only the AGC circuit is used, the AG
If the amplitude of the reproduction signal from the medium having a dynamic range determined by C or more varies, the amplitude cannot be made constant, and medium compatibility, recording device compatibility, and reproduction device compatibility cannot be achieved. It will be difficult.

To solve this problem, Japanese Patent Laid-Open No. 5-62
In Japanese Patent Laid-Open No. 202-202, an amplifier for amplifying a signal reproduced from an optical recording medium is provided, an average amplitude value or a maximum amplitude value of a reproduced signal is detected in a predetermined recording area of the recording medium, and the amplifier is amplified based on the detected value. Of the optical information reproducing device having means for varying the gain of the control signal and controlling the amplitude value of the reproduction signal to a predetermined value.

[0006]

However, in the above-mentioned Japanese Patent Application Laid-Open No. 5-62202, the average amplitude value or the maximum amplitude value of the reproduced signal in the ID portion of each sector is detected, and the amplifier amplitude is detected based on the detected value. In the method of varying the gain, the amplitude level of the reproduced signal increases and does not remain constant from the inner circumference to the outer circumference sector even for the same ID part, so that the gain of the amplifier set in the sector closer to the inner circumference is closer to the outer circumference. If you try to reproduce the sector, it will be saturated beyond the dynamic range of the amplifier, or conversely, if you amplify the reproduced signal of the sector near the inner circumference with the gain of the amplifier set in the sector near the outer circumference, the amplitude level becomes too small, The playback signal may become unreadable. for that reason,
There is a problem that the processing speed becomes slower because the rotating disk has to be rotated once more in order to determine the gain of the amplifier. Further, if the gain of the amplifier is increased, the C / N ratio does not change, but the noise level as well as the carrier level is amplified, which may cause a problem in the binarization process.

Therefore, according to the present invention, the optimum laser power value is taken into consideration in consideration of the combination of the optical information reproducing apparatus and the optical recording medium without being affected by the specifications such as the type of the optical recording medium used and the reflectance. It is an object of the present invention to provide an optical information reproducing device that can be reproduced by.

[0008]

In order to achieve the above object, the present invention is an optical system having a control track area in which information peculiar to an optical information medium is recorded and a user area in which arbitrary information for a user is recorded. In an optical information reproducing device that irradiates a recording medium with spot-shaped laser light from a laser element and reproduces the recorded information from the reflected light, detects the signal level of the information reproduced from the control track area. Driving the laser element based on the signal level held by the level setting means, which has level setting means for varying and setting and holding the power value of the laser light for reproduction so that this signal level becomes a predetermined level Provided is an optical information reproducing device which reproduces information recorded in another area by laser light irradiated with a signal.

Further, the optical recording medium having a control track area in which information peculiar to the optical information medium is recorded and a user area in which arbitrary information for the user is recorded is irradiated with spot-shaped laser light by a laser element, In an optical information reproducing method for reproducing information recorded from the reflected light, a step of reproducing unique information recorded in the control track area before reading arbitrary information from the user area, Detecting the peak value from the reproduced signal of the reproduced information, and the peak value of the reproduced signal of the laser element so that the peak value of the reproduced signal becomes a preset predetermined peak value for obtaining the reproduced signal of information of a desired level. A step of varying the drive current, holding the peak value of the reproduction signal that is equal to the predetermined peak value, and based on the held peak value. To provide an optical information reproducing method consists of driving current of the laser element in the step of reproducing any information from the user area.

According to the optical information reproducing apparatus having the above-mentioned structure, the peak value of the control track area becomes an appropriate peak value for the reproducing apparatus based on the peak value of the reproduced analog signal in the control track area of the optical recording medium. The data is reproduced by changing the reproduction laser power as described above.

[0011]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows a schematic configuration example of an optical information reproducing apparatus as a first embodiment according to the present invention, and will be described. Here, in the present embodiment, as an example of the optical information reproducing apparatus, a magneto-optical disk apparatus using a magneto-optical disk as an optical recording medium is taken as an example. Further, although the ordinary magneto-optical disk device is not exclusively for reproduction but can perform recording, the recording operation is irrelevant to the gist of the present invention, and therefore its explanation is omitted.

An example of the format of the magneto-optical disk 1 used in this embodiment is shown in FIG. This format is I
It was decided as a standard by SO (International Standardization Committee). The disc is roughly divided into a control track area in which information peculiar to the disc such as a medium type and a maker is written, and a user area in which user data is written. That is, the user area at the center is sandwiched by the control track areas on the inner and outer circumference sides.

The magneto-optical disk device shown in FIG. 1 has a spindle motor 2 for rotating a magneto-optical disk 1 as an optical recording medium. When the magneto-optical disk 1 is inserted into the apparatus, a loading (not shown) is provided. The magneto-optical disk 1 is mounted on the spindle motor 2 by a mechanism so as to be rotationally driven.

A pickup 3 as an optical head is provided in the vicinity of the spindle motor 2 so as to be movable in the radial direction of the magneto-optical disk 1, and a laser beam 4 for recording and reproducing is directed toward the magneto-optical disk 1. Irradiate.

The pickup 3 has a laser element for emitting a laser beam, for example, a laser diode (LD) 5
And a detector 6 for receiving the reflected light from the magneto-optical disc 1, the laser light from the laser diode 5 is narrowed down to a minute spot and emitted, and the reflected light from the magneto-optical disc 1 is guided to the photo detector 6. An optical system (not shown) is provided.

An LD driver circuit 7 is connected to the laser diode 5, and a drive current is supplied from the LD driver circuit 7. On the other hand, an analog signal processing circuit 9 is connected to the photodetector 6 via a head amplifier 8 so that the output signal of the detector 6 is amplified by the head amplifier 8 and binarized by the analog signal processing circuit 9. Has become. Further, the magneto-optical disk device is provided with a focusing mechanism and a tracking mechanism which are not shown.

When the magneto-optical disk 1 is inserted into the apparatus, the drive controller 10 sends an instruction of a mode for emitting light with the reproduction laser power to the LD driver circuit 7, and the LD driver circuit 7 outputs a read power equivalent to the read power. The drive current is output to the laser diode 5. The laser diode 5 emits a laser beam 4 having a read power by this drive current, and irradiates the magneto-optical disk 1 with the laser beam 4 for reproduction through the optical system of the pickup 3.

Here, the reflected light reflected by the magneto-optical disk 1 is received by the detector 6 in the pickup 3. The output signal of the detector 6 is amplified by the head amplifier 8 and then input to the analog signal processing circuit 9 to output 2
Valued. 2 binarized by the analog signal processing circuit 9
The digitized signal is sent to the drive controller 10, demodulated and error-corrected, and read as the data recorded on the magneto-optical disk 1.

The read data is sent to a host computer (not shown) for various processing. The magneto-optical disk device reads the control track area when the power is turned on and the device starts up, or when a disc is inserted into the device, and if it is determined that the currently inserted disc is other than the magneto-optical disc, it is inserted. It does not play the recorded disc.

Next, FIG. 2 shows a portion of the analog signal processing circuit 9 and the drive controller 10 shown in FIG. First, the reproduced signal amplified by the head amplifier 8 is the envelope detector 1
At 1, the peak value is detected. As shown in FIG. 3, when the reference predetermined value (peak value) is AV, and when the medium A having a small reflectance is mounted on the apparatus, the peak value becomes A-ΔvV. At this time, the laser drive current is increased to the reference predetermined value AV, and the peak value of the reproduction signal is held at a constant level to reproduce the data.

The peak value when the medium B having a high reflectance is mounted on the apparatus is A + ΔvV. At this time, the laser drive current is reduced to be equal to the reference predetermined value AV, and the peak value of the reproduction signal is held at a constant level to reproduce the data.

The crest value obtained by the envelope detector 11 is digitally converted by the A / D converter 12, and the processing unit (CPU) 13 compares it with a predetermined crest value suitable for a predetermined reproducing device. . When the obtained peak value is not the predetermined value, the D / A converter 1
By changing the value of 4, a drive current is given to the LD driver 7 to convert the laser power for reproduction.

Next, with reference to the flow chart shown in FIG. 4, the operation in the initial state in the optical information reproducing apparatus of this embodiment will be described in detail. First, each part starts up when the power is turned on, the disc is inserted, the disc is rotated,
Initial operations such as light emission, focusing, and tracking operations of the laser diode 5 are performed (step S1). Next, after moving the pickup 3 onto the control track area (step S2), the information recorded in the control track area is read (step S3).

Next, the crest value of the signal read from the control track area shown in FIG. 1 is detected by the envelope detector 11 (step S4). Next, the crest value of the detected signal is digitally converted by the A / D converter 12 as described above, and the CPU 13 compares the crest value with a predetermined crest value suitable for reproduction which is empirically predetermined (step S5). . In this comparison, if the obtained crest value is different from the predetermined crest value (NO), the crest value of the signal detected from the control track area is adjusted to the predetermined crest value. That is, CPU1
3 changes the output value of the D / A converter 14 to change the drive current of the LD driver 7 to cause the laser diode 5 to emit light at a reproduction laser power value that gives a predetermined peak value (step S6). .

When the peak value of the reproduction signal reaches the predetermined peak value (YES), the peak value is set.
Hold (step S7). After the peak value is set, the data reproducing operation is performed.

As described above, in this embodiment, by controlling the reproduction laser power so that the crest value of the control track reproduction signal becomes a predetermined crest value, the crest value of the reproduction signal is changed to an appropriate level and data is reproduced. Can be played.

Further, in the present embodiment, control is performed so as to have one predetermined peak value, but it may be within a permissible range of the peak value that can be properly reproduced. The allowable range varies depending on the reproducing apparatus and the storage medium, and it is necessary to empirically find a suitable one by actually operating it.

In the present embodiment, a magneto-optical disk is used as an example of the optical recording medium, but the present invention is not limited to this. The present invention uses a phase change type disk or a write disk. Once type, read only type, etc.
Any kind of optical recording medium may be used as long as the recording medium has a control track area.
Furthermore, the present invention can be applied to the case of reproducing a disc having a different reflectance or a slightly different sensitivity.

[0029]

As described above in detail, according to the present invention, the combination of the optical information reproducing apparatus and the optical recording medium is not affected by the specifications of the type and reflectance of the optical recording medium used. In consideration of the above, it is possible to provide an optical information reproducing apparatus capable of reproducing with an optimum laser power value.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration example of an optical information reproducing apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a characteristic part of the present embodiment of the analog signal processing circuit and the drive controller shown in FIG.

FIG. 3 is a diagram showing an output waveform of an envelope detector in a VFO section of a control track.

FIG. 4 is a flowchart for explaining an operation in an initial state before reading data in the optical information reproducing device according to the present embodiment.

FIG. 5 is a diagram showing an example of a format of a magneto-optical disk used in this embodiment.

FIG. 6 is a diagram showing a configuration of a reproduction signal processing system in a conventional optical information reproducing apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Magneto-optical disk, 2 ... Spindle motor, 3 ... Pickup, 4 ... Reproducing laser light, 5 ... Laser diode, 6 ... Photodetector, 7 ... LD driver circuit, 8
... head amplifier, 9 ... analog signal processing circuit, 10 ... drive controller, 11 ... envelope detector,
12 ... A / D converter, 13 ... CPU, 14 ... D / A
converter.

Claims (3)

[Claims] 1. A spot-shaped laser beam is irradiated from a laser element onto an optical recording medium having a control track area in which information peculiar to the optical information medium is recorded and a user area in which arbitrary information for a user is recorded, In an optical information reproducing device for reproducing information recorded from the reflected light, a signal level of information reproduced from the control track area is detected, and reproduction is performed so that the signal level becomes a predetermined level. Of the laser beam emitted by the drive signal of the laser element based on the signal level held by the level setting means for changing the power value of the laser light and setting and holding the information recorded in another area. An optical information reproducing device characterized by reproducing. 2. An optical recording medium having a control track area in which information peculiar to the optical information medium is recorded and a user area in which arbitrary information for a user is recorded is irradiated with spot-shaped laser light by a laser element, In an optical information reproducing device for reproducing information recorded from the reflected light, reproducing means for reproducing the information recorded from the control track area, and a peak value of a reproduced signal of the information reproduced by the reproducing means. A crest value detecting means for detecting the crest value of the reproduction signal detected by the crest value detecting means, and preset to be an output value of laser light for obtaining a reproduction signal of information at a desired level. When the crest value of the reproduction signal and the predetermined crest value are different as a result of comparison by the comparing means for comparing with a predetermined crest value and the comparison means. A crest value control means for varying the power value of the laser light so that the crest value of the reproduction signal becomes the predetermined crest value; and a laser beam based on the crest value set by the crest value control means. An optical information reproducing apparatus, which reproduces information recorded in another area with the power value of 1. 3. An optical recording medium having a control track area where information peculiar to the optical information medium is recorded and a user area where arbitrary information for the user is recorded is irradiated with a spot-shaped laser beam by a laser element, In the optical information reproducing method for reproducing the recorded information from the reflected light, reproducing the specific information recorded in the control track area before reading arbitrary information from the user area, Detecting the peak value from the reproduced signal of the reproduced information, and the peak value of the reproduced signal of the laser element so as to be a predetermined predetermined peak value for obtaining the reproduced signal of information of a desired level. A step of varying the drive current, holding the peak value of the reproduction signal that is equal to the predetermined peak value, and based on the held peak value An optical information reproducing method characterized by the driving current of over laser device is constituted by a step of reproducing any information from the user area.