JP2637258B2 - Phase change optical disk device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a phase change optical disc for recording / reproducing or erasing information on a phase change optical disc capable of rewriting or overwriting information, for example. Related to the device.

(Prior Art) As is well known, a phase-change optical disc requires rewriting of information for writing another information after erasing the recorded information or overwriting for writing another information on the recorded information. It is possible.

By the way, this kind of phase change optical disk is used for long-term storage,
Alternatively, the recording film and the protective film may be deteriorated due to repeated recording / erasing of information. In an optical disc having such deterioration, the reflectivity of the recording film fluctuates from the initial state, so that information cannot be accurately written.

However, in a phase change optical disk device that writes information to a phase change optical disk, the deterioration of the recording film and the protective film is not observed. For this reason, there is a problem that information is written to the phase-change optical disk despite the deterioration.

(Problems to be Solved by the Invention) As described above, in the related art, since the deterioration of the recording film and the protective film has not been observed, writing of information to the phase-change optical disk despite the deterioration has occurred. There was a problem that it was performed.

Therefore, the present invention can easily detect deterioration of a phase change optical disk due to long-term storage or repeated recording / erasing, and prohibit writing of new information when the phase change optical disk has deteriorated. It is an object of the present invention to provide a phase change optical disc device capable of performing the above.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, in the phase change optical disc apparatus of the present invention, a phase change optical disc on which information can be rewritten or overwritten is provided. In a phase change optical disk device for recording / reproducing or erasing information,
At the initial stage of the phase change optical disk, the reflectance variation range of the recording film in the amorphous state before initialization, the reflectance variation range of the initialized recording film in the crystalline state, the reflectance variation range of the recording film in the recording portion, Setting means for setting the reflectance variation range of the recording film of the erasing portion, and detecting means for detecting the reflectance of the reflected light when reproducing the recorded information of the phase change optical disc,
The reflectance detected by the detecting means is compared with the four reflectance variation ranges set by the setting means, and the reflectance is deviated from at least one of the four reflectance variation ranges. Prohibition means for prohibiting rewriting or overwriting when there is a

(Operation) According to the present invention, when the protective film or the recording film is deteriorated due to long-term storage or repeated recording / erasing, the reflectance of the reproduction light is greatly changed. The reflectance of light is the reflectance variation range of the amorphous recording film before initialization, the reflectance variation range of the initialized crystalline recording film, and the reflectance of the recording film of the recording portion set at the time of initialization. Rewriting or overwriting information on the phase-change optical disc when the variation range and the reflectance variation range of the recording film of the erased portion deviate from at least one of the reflectance variation ranges. The writing is prohibited.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 3 shows a reproduction waveform of the phase change optical disk.

The phase change optical disk is provided with a recording film made of a compound semiconductor such as InSbTe. This recording film is usually in an amorphous state at the initial stage, and is in an initial crystallization state by light beam irradiation or oven annealing. In the case of a phase change optical disk using a compound semiconductor such as InSbTe for a recording film, its reflectivity is greatly reduced by initial crystallization.

When information such as overwriting is recorded,
The recording film in the recording bit portion corresponding to the information “1” has a crystalline structure close to an amorphous state, and the recording film in the erased portion corresponding to the information “0” has a structure close to a crystallized state.

At the initial stage, the reflectance of the recording film in the amorphous state is set to be in the range as shown in FIG. A, and the reflectance of the recording film in the initial crystallization state is in the range as shown in FIG. The reflectance of the recording film in the recording bit portion is set to be in the range as shown in FIG. C, and the reflectance of the recording film in the erased portion is in the range as shown in FIG. Each is set as follows.

FIG. 1 shows a configuration of a phase change optical disk apparatus for rewriting or overwriting information on the phase change optical disk.

In the case of this optical disk device, amplitude detection (for example, “signal processing technology in optical recording”,
(Supervised by Tanaka, published by Trikeps, 1989, 2, 20), and the original recording waveform is obtained by binary-comparing the reproduced signal with an appropriate threshold value. As a frequency for tracking and focus signal detection, a frequency lower than a recording signal is used.

That is, the phase change optical disk 11 is rotated at a constant speed by the motor 12, for example.

On the other hand, the optical head has a semiconductor laser 13 as a light source,
A transmission optical system 15 composed of optical components such as a condenser lens 14, a prism, a mirror, and a wavelength plate, and a tracking error detection optical system mainly including a photodiode as a photodetector.
16 and a focusing error detection optical system 17.

The servo circuit 18 controls the servo drive mechanism 19 based on the detection outputs from the tracking error detection optical system 16 and the focusing error detection optical system 17, thereby
14 for focus control and tracking control.

The signal detection circuit 20 obtains an original recording waveform by binary-comparing the reproduction signal with an appropriate threshold value.

The reflectance detection circuit 21 is configured to reflect the reflectance from the recording film in the amorphous state, the reflectance from the recording film in the initial crystallization state, the reflectance from the recording film in the recording bit portion, and the reflectance in the erasing portion. At least one of the reflectances from the recording film is detected.

The write prohibition circuit 22 detects the deterioration of the phase change optical disk 11 based on the reflectance from the reflectance detection circuit 21. That is, the deterioration of the phase-change optical disc 11 is detected by comparing the reflectance detected by the reflectance detection circuit 21 with a preset initial reflectance, for example.

Here, the reflectance at the initial stage is, for example, the third reflectance.
As shown by A, B, C, and D in the figure, the fluctuation range is set at the DC (direct current) level of the reproduced waveform. And
This initial reflectance may be recorded in advance on the phase change disk 11 as a partial ROM, or may be recorded before use. Further, the phase change optical disk device may be provided with control data of the phase change optical disk 11.

On the other hand, for example, when one or more of the reflectances detected by the reflectance detection circuit 21 deviate from the initial reflectance, the write inhibit circuit 22 Is displayed on the display device 23, and the semiconductor laser 13 is controlled to write the write-inhibition information into a predetermined sector of the optical disk 11, for example.

The display device 23 informs the user that the phase change optical disc 11 is deteriorated, for example, by an error code, a signal display, a character display, or the like.

FIG. 2 shows an example of a sector format in the phase change optical disk 11.

Normally, when information is recorded on the phase-change optical disk 11, the information is performed according to this recording format.

That is, one sector includes a preformat unit and a recording / reproducing unit.

The preformat section is a pattern prerecorded in the optical disc 11 with prepits, and is divided into a sector synchronization section and an address section.

The sector synchronization section is for surely identifying a break between sectors, and a sector mark serving as a reference for data recording / reproduction timing is recorded here.

The address part is a part indicating the physical address of the sector.

The recording / reproducing section includes a flag recording section, a recording power check section, a data synchronization section, a data section, and a gap section.

In the flag recording unit, information indicating the use status of the sector, such as information indicating whether the sector has been recorded, information indicating whether the sector has been normally recorded, and the above-described write inhibit information are recorded. It has become.

The recording power check unit is for obtaining the optimum applied current to the semiconductor laser 13 by causing the semiconductor laser 13 to emit test light before recording information and monitoring the output power.

The data synchronizing unit includes a part for synchronizing bits and a synchronizing pattern part for synchronizing data.

In addition to user data, control information for sector management, check bytes required for error correction, and a resynchronization pattern for resynchronizing data are added to the data portion.

The gap portion is a non-recording portion necessary for reliably separating the sector from the next sector.

 Next, the operation in the above configuration will be described.

For example, if an attempt is made to rewrite or overwrite information on the phase-change optical disk 11,
As a result, the phase-change optical disk 11 is rotated, and the optical head is moved to the information recording position.

Then, based on the reflected light from the recording film due to the light irradiation of the semiconductor laser 13, the condensing lens 14 is provided at the recording position.
Are tracked and focused by the servo circuit 18 and the servo drive mechanism 19.

Further, the reflectance of the reproduction light from the phase-change optical disc 11 is detected by the reflectance detection circuit 21. Then, the detected reflectance is sent to the write-protection circuit 22, where it is used for detecting the deterioration of the phase-change optical disk 11. That is,
The level of the reproduced waveform detected by the reflectance detection circuit 21 is compared with the initial reflectance variation ranges A, B, C, and D, respectively.

If no deterioration of the phase-change optical disc 11 is detected by the comparison, information is rewritten or overwritten at the recording position.

On the other hand, when the deterioration of the phase change optical disc 11 is detected,
In other words, when the level of the reproduced waveform is out of the initial range of the reflectance variation in at least one or more areas, the semiconductor laser 13 writes the write-inhibition information into, for example, the flag recording section of the sector. .
Further, the display circuit 24 indicates that rewriting or overwriting of information on the optical disk 11 is prohibited due to the deterioration of the phase change optical disk 11.

As described above, the deterioration of the optical disk is detected by monitoring the reflectance of the reproduction light during use.

That is, the deterioration of the protective film or the recording film due to long-term storage or repeated recording / erasing is detected based on the fluctuation of the reflectance of the reproduction light from the initial stage, and if the deterioration is detected, a flag is set to change the phase. Rewriting or overwriting of information on the optical disk is prohibited. This makes it possible to prevent a problem that new information is recorded on an optical disc that has deteriorated. Therefore, even if information is repeatedly written, the optical disk cannot be degraded for the first time because the recorded signal cannot be accurately reproduced by read-after-write after the information is recorded, and another optical disk must be prepared and the information recorded again. It is to be solved from inconvenience such as having to do.

In the above embodiment, a phase change optical disk using an InSbTe compound semiconductor for the recording film has been described as an example. However, the present invention is not limited to this. The present invention can also be applied to an optical disk used as an optical disk.

Of course, various modifications can be made without departing from the scope of the present invention.

[Effects of the Invention] As described above in detail, according to the present invention, the reflectance of the reproduction light that fluctuates when the protective film or the recording film is deteriorated is monitored, so that long-term storage or repetition of the storage can be performed. Provided is a phase change optical disk device that can easily detect deterioration of the phase change optical disk due to recording / erasing and can prohibit writing of new information when the phase change optical disk is deteriorated. it can.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention. FIG. 1 is a block diagram showing a configuration of a phase change optical disk device, FIG. 2 is a diagram showing an example of a sector format, and FIG. It is a figure which shows typically. 11 ... Phase change optical disk, 13 ... Semiconductor laser, 20 ...
Signal detection circuit, 21 ... Reflectance detection circuit, 22 ... Write-protection circuit.

Claims (1)

(57) [Claims] 1. A phase change optical disk apparatus for recording / reproducing or erasing information on a phase change optical disk capable of rewriting or overwriting information, comprising: The reflectance variation range of the recording film in the state, the reflectance variation range of the initialized recording film in the crystalline state, the reflectance variation range of the recording film in the recording portion, and the reflectance variation range of the recording film in the erasing portion are set. Setting means; detecting means for detecting the reflectance of the reflected light when reproducing the recorded information of the phase change optical disc; and the reflectance detected by the detecting means and the four reflectance fluctuations set by the setting means. And a prohibition unit for prohibiting rewriting or overwriting when the range is out of at least one of the four reflectance variation ranges. A phase-change optical disc device, comprising: