JPH01298545A - Disk-shaped optical information recording medium and its production - Google Patents

Abstract

PURPOSE:To obtain the disk-shaped optical information recording medium which can form good pits over the entire surface of the disk by using a material having a high thermal conductivity as a reflecting film in the part where a line speed is low and using a reflecting film having a low thermal conductivity in the part where the line speed is low. CONSTITUTION:A protective layer 23 is deposited on a substrate 22 formed of polycarbonate or acrylic resin, etc., and the material such as Sb2Te3-GeTe having a high crystallization rate is deposited as a recording layer 24 thereon. Further, a protective layer 25 is deposited thereon. The material such as Au, Ag, Cu or Al having the high thermal conductivity is deposited to the sound region in the inner circumferential part as the reflecting layer 26 on the protective layer 25 and the material such as Ni, Cr or Pt having the low thermal conductivity is deposited on the video region in the outer circumferential part. The heat required for recording is, therefore, more easily diffused in the region where the line speed is low. Rapid cooling is attained therein and the recrystallization of the amorphous recording pits is prevented. The diffusion of the heat is low in the region where the line speed is low and, therefore, the recording with relatively small power is possible.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is capable of recording, erasing, and reproducing information signals with high density and high speed by changing the optical properties of a film using light heat such as a laser beam. The present invention relates to a disk-shaped optical information recording medium that can be used as an optical information recording medium, and a method for manufacturing the same.

[Conventional technology]

2. Description of the Related Art Optical discs such as CDs, CDVs, and LDs that read signals and reproduce music and videos using laser light have become widely used. However, users cannot record or erase information on these optical discs by themselves. Therefore, in order to obtain a rewritable optical disk, recording films have been proposed, such as a magneto-optical method that uses rotation of the plane of polarization due to the orientation of a magnetic moment, and a phase change method that uses a crystal-amorphous phase change. Recording films based on the latter phase change method are known to have Tet ln, 3e, etc. as their main components, and by laminating a protective film on such a recording film as is well known, long-life optical information recording is possible. You can get the medium.

[Problem that the invention seeks to solve]

However, if a material with high thermal conductivity is used as such a protective film, if the linear velocity during recording is high, the light irradiation area will not reach the temperature required during recording due to excessive heat dissipation, and recording will not be possible. It becomes difficult. For this reason, using a protective film with low thermal conductivity solves the above disadvantages, but conversely, if the linear velocity during recording is low, the light spot passes slowly and heat is difficult to diffuse, so the light The cooling rate after passing through the spot is slow, and the recording pits that once became amorphous are slowly cooled and crystallized again. For this reason, it has been difficult to perform good recording on an optical disc in which a single disc has a high linear velocity area and a low linear velocity area.

Therefore, it is an object of the present invention to provide a hollow disk type optical information recording medium in which a good pit is formed over the entire surface of the disk.

[Means for solving problems]

In the recording information medium of the present invention, a material with high thermal conductivity is used as a reflective film in areas where the linear velocity is slow, and a reflective film with low thermal conductivity is used in areas where the linear velocity is high.

[Effect]

Therefore, in a region where the linear velocity is slow, the heat required for recording is easily diffused, rapid cooling can be achieved, and recrystallization of amorphous recording bits can be prevented. Furthermore, since there is less heat diffusion in areas where the linear velocity is high, recording can be performed with relatively little power.

〔Example〕

1 and 2 are a top view and a sectional view showing an example of the case where the present invention is applied to a disc (CDV) having a video area and an audio area. Like a normal audio compact disc (ODA), the audio signal is converted to a PCM signal and recorded, and on the outer periphery, like a video disc, the video signal is converted to an FM signal and recorded. .

As shown in FIG. 2, a protective layer 23 of S i Oz, A IN, S i z N+, etc. is deposited on a substrate 22 made of glass, polycarbonate, acrylic resin, or the like by sputtering.

A recording layer 24 made of a material having a high crystallization rate such as Sbg 7'e3-GeTe is deposited over the entire surface of the protective layer 23 thus formed.

Furthermore, a protective layer 25 similar to the above-mentioned protective layer 23 is deposited thereon.

Furthermore, in order to deposit a reflective layer 26 on the protective layer 25 and a reflective layer such as Au only on the inner periphery, the outer periphery is masked with a donut-shaped metal plate, etc. Prevent Au etc. from adhering to the outer periphery. Further, in order to coat a reflective layer such as Ni on the outer periphery, a disk-shaped mask is applied to the inner periphery.

As is well known, the thickness of the protective layer 23 is determined so as to minimize deterioration of the substrate due to heat due to repeated laser beam irradiation and deterioration of the recording layer 24 due to temperature.

Further, the thickness of the protective layer 25 is determined so as to obtain appropriate thermal conductivity characteristics together with the reflective layer 26, and to reduce deterioration of the recording layer due to temperature.

In addition, the film thickness of the recording layer 24 is as follows: the protective layer 23.25 and the reflective layer 2.
It is selected so that the difference in reflectance between the recorded portion and the unrecorded portion is maximized due to the interference effect with No. 6.

In the audio area of the inner circumference of the optical disc created in this way,
As the recording light beam 21 at a linear velocity of 1.4-/S, the wavelength is 83
Irradiate 0ns semiconductor laser light through the substrate 22,
When the same EFM digital audio signal as on a CD was recorded, good pits were formed. Furthermore, when an FM video signal was similarly recorded in the video area at the outer periphery at a linear velocity of 1)@/s, good pits were also formed.

Regarding erasing characteristics, since the crystallization speed of the recording layer is extremely fast, ranging from tens to hundreds of nanoseconds, erasing is possible by adjusting the laser power so that the temperature does not melt the recording layer and is at least the crystallization temperature. .

〔Effect of the invention〕

As described above, according to the present invention, it is possible to obtain well-shaped pits in an optical information recording medium having a fast linear velocity area and a slow linear velocity area within the same disk.

[Brief explanation of the drawing]

FIG. 1 is a top view of an optical information recording medium according to the present invention, and FIG. 2 is a sectional view thereof. 1)...Video area 12...Audio area 21
...Laser light 22...Substrate 23.25.
...Protective layer 24...Recording layer 26...Reflection layer Fig. 1

Claims (2)

[Claims] (1) A disc-shaped optical information recording medium in which a recording film and a reflective film are laminated on a substrate, characterized in that the reflective film on the inner periphery is made of a material with higher thermal conductivity than the outer periphery. Optical information recording medium. (2) a step of shielding one of the outer circumferential portion or the inner circumferential portion on the substrate and forming a reflective film having a first thermal conductivity on the other;
A method for manufacturing a disk-shaped optical information recording medium, comprising the step of forming a reflective film having a second thermal conductivity on one side while shielding the other side.