JPS63142548A - Rewriting type optical disk - Google Patents

Abstract

PURPOSE:To permit initialization of the track part in a data region by using an ordinary device by previously providing tracks for focusing having the reflectivity necessary for focusing retraction to the outside of the tracks in the data region. CONSTITUTION:The track part 21 for focusing is previously formed of a dielectric layer 17 and a reflection layer 18 and is provided with the reflectivity higher than in the track part 20 of the data region. Focus control is executed by bringing an optical head toward the track part 21 of a disk 14. The track part 21 near the track part 20 is thereafter retrieved and while an erasing beam is projected, the optical head is moved to the track part 20. The optical head attains the crystal state of the high reflectivity as a recording or reproducing beam follows up successively the track projected with an erasing beam. The stable focus control is thus executed. The initialization processing with the ordinary device is permitted by using such disk.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to a rewritable 2-inch optical disc on which recording and erasure can be performed.

BACKGROUND OF THE INVENTION In recent years, rewritable optical discs that utilize changes in crystalline states have been developed as optical disc memories, and are expected to be applied to information files and the like. FIG. 2 shows the wavelength dependence of such a rewritable optical disc.

When forming a recording film on a rewritable optical disk that uses such a phase change, a single light beam is irradiated onto the disk that is in an amorphous state with low reflectance to transform it into a crystalline state with high reflectance (after which initialization is performed). (referred to as "processing") and erase records. Furthermore, information is recorded using changes in reflectance between a crystalline state and an amorphous state, and recording using a light emitting light source in a wavelength range with a large change in reflectance improves the S/N ratio. Larger and desirable. Therefore, in the Z optical recording and reproducing apparatus for recording and erasing data on a rewritable disc, recording and erasing is performed using a light emitting light source having a wavelength of λ in the vicinity of FIG. FIG. 3 shows the configuration of a conventional optical recording/reproducing device. In Figure 3,
1 is a disk, 2 is a recording/reproducing light source consisting of a semiconductor laser, 3 is a first collimator lens group that shapes the light beam from the recording/reproducing light source consisting of a semiconductor 3'-/laser into a circular spot, and 4 is an erasing lens. A light source, 6 is a second collimator lens group that shapes the light beam from the erasing light source into an elliptical spot, 6 is a polarizing beam splitter, 7.8ij dead wave plate, 9 is a band pass filter, and 101riM relens is an actuator for focusing. It is supported by 11. 12 is a condensing lens, 1
3 is a photodetector that detects a focus error signal and a reproduction signal.

Light source for recording and reproduction 2. The erasing light source 3 emits light of different wavelengths around the wavelength λ1, and the bandpass filter 9 transmits the wavelength of the recording/reproducing light source 2 and reflects the wavelength of the erasing light source 3. Therefore, the recording/reproducing light travels as shown by the solid line and is focused into a circular shape on the disk, after which the reflected light is detected by the photodetector 13 and becomes a focus signal.

Obtain playback signal. On the other hand, the erasing light travels as shown by the broken line and is condensed into an elliptical shape on the disk to perform erasing.

Problems to be Solved by the Invention However, 1. In a rewritable optical disk having such a configuration, when initialization processing is performed, the following problems occur because the reflectance is low near the wavelength λ1.

When performing initialization processing on an optical recording/playback device, it is necessary to apply focus control to the disk and then irradiate the erase beam to perform the initialization process, but due to the low reflectance of the disk, focus pull-in is unstable. However, it had the disadvantage of not being able to perform initialization processing. In addition, an initialization processing device has been devised for optical recording/reproducing devices that performs focus control using a wavelength near λ2 shown in Figure 2, at which the reflectance from the disk is high. There are disadvantages in that a large laser device such as a He-Ne laser is required as a light source, and a special optical system must be used.

The object of the present invention is to obtain a rewritable optical disc that can be initialized using a conventional optical recording/reproducing device.

Means for solving the problems and technical means of the present invention for solving the above problems are as follows: A vane orcus track having a reflectance necessary for focusing an optical recording/reproducing device is prepared in advance outside the data area track. It was established.

The effect of this technical means is that by providing in advance a focusing track having a reflectance necessary for focusing the optical recording/reproducing device outside the data area track, the optical head of the optical recording/reproducing device can be placed on the track. It becomes possible to perform an initialization process on the data area track section by bringing the data area to the center, performing a focus pull-in operation, and then irradiating the erasing beam.

Embodiments The following five embodiments of the present invention will be described based on the accompanying drawings.

In FIG. 1, 14 is a disk, a substrate having rack grooves, 16 is a recording film, 17 is a dielectric layer, 18 is a reflective layer, and 19 is a protective substrate.

Reference numeral 20 denotes a data area track portion, which is composed of three layers: a recording film 16°, a dielectric layer 172, and a reflective layer 18. Reference numeral 21 denotes a track section for the focus 6 outside the data area track, which is composed of two layers: a dielectric layer 171 and a reflective layer 18, and has a higher reflectance than the data area track section 2o, and serves as a focus for an optical recording/reproducing device. This is an area where retraction is possible.

Next, the operation of the configuration of this embodiment will be explained. First, the optical head of the optical recording/reproducing device is brought to the focus track section 21 of the disk 14, and focus control is performed. Thereafter, a search is made to a track section 21 near the data area track section 20, and the optical head is moved to the data area track section 20 while irradiating the erasing beam. As shown in FIG. 3, since the recording/reproducing beam follows the track irradiated with the erasing beam, the optical head becomes in a crystalline state with high reflectance, and stable focus control can be obtained. Therefore, if a rewritable optical disc having such a configuration is used, initialization processing can be performed using a conventional optical recording/reproducing device.

Effects of the Invention When forming a recording film, the present invention irradiates the disk which is in an amorphous state with a low reflectance with one light beam to transform it into a crystalline state with a high reflectance, and then erases the recording. This is a rewritable optical disc that has a focus track with a reflectance necessary for focusing the optical recording/reproducing device outside the data area track, and is used for initialization processing using the optical recording/reproducing device. This eliminates the need for an expensive initialization processing device as in the past.

Therefore, the disk cost can be reduced and the effect is great.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of a rewritable optical disc according to an embodiment of the present invention, Fig. 2 is a characteristic diagram showing the wavelength dependence of reflectance of a conventional rewritable optical disc, and Fig. 3 is a principle diagram of an optical recording/reproducing device. It is. 14...disc, 16...recording film, 17...
...Dielectric layer, 18...Reflection layer, 2o...Data area track section, 21...Focus track section. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Silver →

Claims (2)

[Claims] (1) A rewritable optical disc in which recording and erasing is performed after the disk, which is in an amorphous state with low reflectance during formation of a recording film, is transformed into a crystalline state with high reflectance by irradiating a light beam, and the data is erased. A rewritable optical disc characterized in that a focusing track having a reflectance necessary for focusing an optical recording/reproducing device is provided in advance outside the area track. (2) The data area track has a three-layer structure of a recording film, a dielectric layer, and a reflective layer, and the focusing track has a dielectric layer and a reflective layer.
Rewritable optical disc as described in section.