JPS63103437A - Optical memory device - Google Patents

Abstract

PURPOSE:To prevent crosstalk due to the expansion of a bit width from being increased, by setting entire plane of the recording film of an optical memory disk before it is used at an amorphous state, performing erasure only on a groove, and performing recording, reproduction, and the erasure on the groove. CONSTITUTION:After a part (between the groove) 5 except the groove (on the groove) 4 where the recording, the reproduction, and the erasure of information are performed on a recording film, is formed in the amorphous state similarly as a recording bit, the recording, the reproduction, and the erasure are performed on the groove 4. Also, at time of erasing the information, a laser power which generates no erasing state (crystallized state) of the part 5 between the groove is set on the recording film. Thus, since the part 5 between the groove is set at the same amorphous state similarly as a write bit, the bit can be read as a bit 7 having the bit shape of a uniform width even when the bit width of a bit 3 recorded on the groove 4 is expanded and it is forced out to the part 5 between the groove. In such way, the crosstalk due to the expansion of the bit width can be completely suppressed.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to optical memory devices.

[Conventional technology]

Figure 2 shows a diagram of the principle of recording, reproducing, and erasing in a conventional phase-transition optical memory.As shown in Figure 2 (α), the recording film is rapidly heated and cooled in a circular spot to prevent the beam from hitting the target. The recorded portion is made amorphous and recorded. The surrounding area is in a crystalline state, and the bit formed by heating and rapid cooling becomes amorphous, and the reflectance of the bit portion is reduced. A reproduced signal is obtained by detecting this change in reflectance using a laser. Erasing is performed by heating and slowly cooling the recording film to return it to a crystalline state using an elliptical beam whose long axis is in the direction of the distribution groove.

The bit shape is shown in FIG. 5. 01 indicates the groove where recording, reproduction, and erasing are performed, and 2 indicates the gap between the grooves. The area shown in 4 is an erased portion, and the recorded bits exhibit a shape in which the pit width gradually increases from the initial stage of writing, as shown in FIG. At the time of erasing, in order to completely erase such bits, the area between the grooves is erased along groove 1 using a laser power that also erases the part between the grooves, resulting in the erased area shown in 4.

[Problem that the invention seeks to solve]

However, as the bit becomes longer, the width of the bit also increases due to heat conduction, so there is a problem that crosstalk increases as the width of the bit increases.

Therefore, the present invention aims to solve these problems.
The purpose is to not increase crosstalk even if the bit length increases.

[Means for solving problems]

The optical memory device of the present invention uses a phase-change recording film that has amorphous and crystalline properties with different reflectances, and the film, which is initially in a crystalline state, is heated and rapidly cooled by condensed laser beam irradiation. The recording film is erased by irradiating the recording film with a laser beam that heats and slowly cools the recording film and crystallizes the recorded film.
In an optical memory device that detects and reproduces changes in reflectance on a recording film using a laser beam, parts other than the grooves (on the grooves) where information is recorded, reproduced, and erased on the recording film (
A laser that performs recording, reproduction, and erasing on the grooves after making the grooves (between the grooves) into the same amorphous state as the recording pits, and does not turn the grooves on the recording film into an erased state (crystalline state) during erasing. A feature is that the power is set at the time of erasing.

[For production]

According to the above structure of the present invention, since the space between the grooves is kept in the same amorphous state as the written bit, even if the pit width of the bit recorded on the groove becomes wider and protrudes between the grooves, the space between the grooves remains the same as the bit. Since it is in an amorphous state, the bit shape is read as a bit with a constant width, and crosstalk due to widening of the pit width is completely suppressed. You don't need enough laser power to erase it. In the above case, since the space between the grooves is not affected during erasing, once the recording surface is in the amorphous state with the full write bits at the initial stage of the disk, it is necessary to make the space between the grooves in the amorphous state from then on. It can be recorded, played back, and erased.

〔Example〕

A principle diagram explaining the pit state on the phase change recording film in the present invention is shown in FIG. This is the part that becomes amorphous. 4 indicates the groove top where recording, reproduction, and erasing are performed, and indicates the range in the crystalline state in the erased state. 5 indicates the area between the grooves. 0 indicates the amorphous state.
As shown in a), the portion of the pit 30 that has been heated and rapidly cooled by the circular laser beam focusing spot becomes an amorphous state, but the portion shown in b is a portion that is originally in an amorphous state and is The shape recorded as a bit is as shown at 7 in FIG. 1(b). Therefore 3
Even if the width of the bit shown in (a) increases, a bit will be formed that is not affected by the change in width. In other words, even if the bit length becomes longer and the pit width widens due to heat conduction or the like, the recognized pit width does not change, so the increase in crosstalk is completely suppressed due to the widening of the pit width.

Erasing is carried out by changing the amorphous state of the recording film to a crystalline state by heating and slow cooling using an oval spot.
By setting and erasing the amorphous state portion to such an extent that it does not crystallize, it is possible to erase without erasing the portion where crosstalk increases and without erasing any remaining portion.

〔Effect of the invention〕

As described above, according to the present invention, before using an optical memory disk, the entire surface of the recording film is brought into an amorphous state, erasing is performed only on the grooves, and recording, reproduction, and erasing are performed on the grooves. This makes it possible to completely suppress the increase in crosstalk caused by widening of the pit width without performing complex optical or electrical processing.

[Brief explanation of the drawing]

FIG. 1(α) is a schematic diagram showing the recording state of the present invention. (b) Schematic diagram showing the pit shape of the present invention 0 (1) Schematic diagram showing the erased state of the present invention. FIG. 2 (α) A schematic diagram showing the recording method. (b) A schematic diagram showing a recording state and a reproduction method. (e) Schematic diagram showing the erasing method. Fig. 6 Schematic diagram showing the conventional recording, reproducing, and erasing states. 1...Groove where recording, playback, and erasing are performed 2...Groove gap 3...Pit 4...Erasing range 6...Part that is not recognized as an actual pit 7...
Partial board written as an actual pit Upper applicant Seifu Ebson Co., Ltd. (≦shi) (button)

Claims (2)

[Claims] (1) Using a phase-change recording film that has amorphous and crystalline properties with different reflectances, the film, which is initially in a crystalline state, is irradiated with focused laser light to heat up and rapidly cool down only that part. The recording film is made amorphous and recorded, the recording film is crystallized by irradiating the recording film with a laser beam that heats and slowly cools the recording film, and the recording film is erased. Changes in reflectance on the recording film are detected by the laser beam and reproduced. In an optical memory device that performs a -An optical memory device that is characterized by playback and erasing. (2) The optical memory device according to claim 1, wherein a laser power that does not bring the grooves on the recording film into an erased state (crystalline state) is set during erasing.