JPS61131255A - Optical recording and reproducing disk - Google Patents

Abstract

PURPOSE:To prevent erroneous recording and reproduction and mixing of noises by providing a digital signal pit and a metallic reflective film on the surface of the groove of a disk furnished with tracks, and furnishing a protective film consisting of a high-hardness metallic thin film on the metallic reflective thin film. CONSTITUTION:An optical recording and reproducing disk 1 consists of a disk 2 of a transparent plate, a metallic reflective film 3, a protective film 4, and a digital signal pit 5. The disk 2 is formed with an acrylic or a polycarbonate transparent synthetic resin, the metallic reflective film 3 of an aluminum and silicon alloy, etc. is formed on the surface contg. the signal pit 5 by vapor deposition or sputtering, and the protective film 4 is provided on the film 3. The protective film 4 consists of a high-hardness metallic thin film. At least on of the metals between cobalt and nickel is used as the metal, and the film 4 is formed on the metallic reflective film 3 by vapor deposition or sputtering. By such a structure, generation of flaws due to impact is eliminated, and erroneous recording and reproduction and mixing of noises can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an optical recording/reproducing disk used in an optical recording/reproducing device.

[Background of the invention]

In general, for digital recording and reproducing devices such as video discs and compact discs, optical video discs and compact discs must have high mechanical strength, excellent heat resistance and moisture resistance, and small change over time. It is desired that the front and back surfaces of the tracking grooves of the discs be less likely to be scratched. This is because scratches on the surface of the groove or the back surface of the disc may cause erroneous recording, erroneous playback, and noise.

An optical recording/reproducing disk is composed of a disk made of a transparent plate, a metal reflective film, and a protective film.

In conventional optical recording/reproducing disks, since the protective film 4 is formed by coating with acrylic synthetic resin, it has the disadvantage that it is easily scratched and its characteristics change over time due to changes in temperature and humidity. Japanese Patent Publication No. 58-1751
No. 54 discloses an invention that improves these drawbacks.

[Purpose of the invention]

An object of the present invention is to provide an optical recording/reproducing disk that is free from erroneous recording, erroneous reproduction, and noise.

[Summary of the invention]

The present invention is intended to provide a protective film that does not have such drawbacks.

In the present invention, the protective film is made of at least one of cobalt and nickel.
In addition, digital signal pits, a metal reflective film, and a protective film are formed on the groove surface of the tracking disk.

[Embodiments of the invention]

FIG. 1 shows an outline of an optical recording/reproducing disk.

FIG. 2 is a detailed sectional view of a portion of FIG. 1, and FIG. 3 is an enlarged plan view of a signal pit.

In FIGS. 1, 2, and 3, reference numeral 1 denotes an optical recording/reproducing disk, which is composed of a disk 2 made of a transparent plate, a metal reflective film 3, and a protective film 4. 5 is a digital signal pit. The disk 2 is made of a transparent synthetic resin such as acrylic or polycarbonate, and a metal reflective film 3 is formed on the surface containing the signal pits 5 using an aluminum-silicon alloy or the like by vapor deposition or sputtering. A protective film 4 is provided on top.

The protective film 4 of the present invention is made of a highly hard metal thin film.

The metal used is at least one of cobalt and nickel, and is formed on the metal reflective film 3 by vapor deposition or sputtering. The thinner these metal thin films are, the better, but considering the smoothness of the surface, a thickness of 5 μm to 50 μm is appropriate.

〔Effect of the invention〕

As described above, the optical recording/reproducing disk of the present invention has a structure in which digital signal pits and a metal reflective film are provided on the groove surface of a tracking disk made of a transparent plate, and a highly hard metal is provided on the metal reflective film. Because it has a thin protective film, it is far less susceptible to mechanical changes over time, such as scratches from impact and warping due to changes in temperature and humidity, compared to discs with conventional synthetic resin protective films. This has the effect of achieving the object of the present invention.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an optical recording/reproducing disk, FIG. 2 is an enlarged sectional view of a portion of FIG. 1, and FIG. 3 is an enlarged plan view of digital signal pits. DESCRIPTION OF SYMBOLS 1... Optical recording/reproducing disk, 2... Disc, 3... Metal reflective film, 4... Protective film, 5... Digital signal pit. %, -〉'1 Animal 1 Figure ¥3 Figure

Claims (1)

[Claims] 1. A tracking disc made of a transparent plate has digital signal pits and a metal reflective film on its groove surface, and a protective film made of a highly hard metal thin film is provided on the metal reflective film. An optical recording and reproducing disc characterized by: 2. The protective film contains at least one of cobalt and nickel.
The optical recording/reproducing disc according to claim 1, characterized in that the optical recording/reproducing disc is made of a double-stranded disc.