JPH04263139A - Optical storage material only for reproducing use - Google Patents

Abstract

PURPOSE:To curtail an injection molding cycle to enhance productivity by forming the shape of section in the width direction of a recording pit like a wedge and thereby realizing easy peeling of resin substrate, after injection molding, from a metal stamper. CONSTITUTION:A polycarbonate substrate 1 is covered with aluminum, as an Al reflection film 2, by the high frequency magnetron sputtering method, vacuum evaporation method, etc., and the film 2 is then covered with a protection film 3 of UV setting resin. In the case where the substrate 1 is injection-molded, the shape of section in the width direction of the recording pit is set like a wedge so that the substrate 1 can be peeled easily from the metal stamper after the injection molding. Productivity may be determined by the injection molding cycle and the injection molding cycle can be curtailed to about 1/2, when the bottom surface of storing bit has the shape like a wedge, in comparison with the case where the bottom surface of storing bit is flat. Thereby, productivity can be improved.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a read-only optical storage medium used in audio equipment or information equipment.

0002

[Prior Art] Conventionally, the cross-sectional shape in the width direction of the storage pit of a compact disc, which is a read-only optical storage medium, is a trapezoid or a partial arc, and the shape when viewed from the reflective film side is called a "soccer stadium." ing. (Compact Disc Reader, page 92, co-authored by Heitaro Nakajima and Hiroshi Ogawa; Ohmsha Publishing) In other words, the bottom part is flat. Also,
The shape of the storage pits of conventional video discs is also similar. The substrates of these read-only optical storage bodies are manufactured by injection molding.

0003

The productivity of conventional read-only optical storage media is determined by the injection molding cycle, which takes 15 seconds per disc. Furthermore, this injection molding cycle is determined by the shape of the memory pit. Since the bottom of conventional memory pits is flat, it takes time to separate the resin substrate from the metal stamper after injection molding, and it is impossible to shorten this injection molding cycle to 15 seconds or less. Ta.

An object of the present invention is to make the cross-sectional shape of the recording pit wedge-shaped in the width direction so that the resin substrate can be easily peeled off from the metal stamper after injection molding, thereby shortening the injection molding cycle and improving read-only optical storage media. The purpose is to improve productivity.

[0005]

SUMMARY OF THE INVENTION The present invention is a read-only optical storage medium characterized in that the cross-sectional shape of the recording pits in the width direction is wedge-shaped.

[0006] Examples of the material for this substrate include injection moldable resins such as polycarbonate resin and polyolefin resin.

[0007] Aluminum may be coated on the substrate as a reflective film by high frequency magnetron sputtering, vapor deposition, or the like.

[0008] Furthermore, a resin may be coated as a protective film on the reflective film.

[0009]

[Function] In such a read-only optical memory, the cross-sectional shape of the recording pit in the width direction is wedge-shaped, so the resin substrate easily peels off from the metal stamper after injection molding. The injection molding cycle for the body will be significantly shorter than the injection molding cycle for conventional read-only optical storage bodies.

0010

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a partial sectional view showing an embodiment of the read-only optical storage medium of the present invention. Here, 1 is a polycarbonate substrate, 2 is an A1 reflective film, and 3 is an ultraviolet curing resin protective film. FIG. 2 is a view of the recording pits of the read-only optical storage medium of the present invention viewed from the reflective film side. FIG. 3 is a partial cross-sectional view in the width direction of a recording pit of the read-only optical storage medium of the present invention (cross section AA' in FIG. 2). This is a compact disc.
The injection molding cycle was approximately 8 seconds.

On the other hand, the conventional injection molding cycle for compact discs was about 15 seconds.

[0013]

[Effects of the Invention] As described in detail above, in the read-only optical storage medium of the present invention, since the cross-sectional shape of the recording pits in the width direction is wedge-shaped, the resin substrate after injection molding is removed from the metal stamper. It is easily peeled off, and the injection molding cycle of the read-only optical storage of the present invention can be significantly shorter than that of the conventional read-only optical storage.

Furthermore, although a compact disc has been described as an example here, it is clear that similar effects can be obtained with a video disc.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view showing an embodiment of a read-only optical storage body of the present invention.

FIG. 2 is a diagram of recording pits of the read-only optical storage medium of the present invention viewed from the reflective film surface side.

FIG. 3 is a partial cross-sectional view in the width direction of recording pits of the read-only optical storage medium of the present invention (cross section AA' in FIG. 2).

[Explanation of symbols]

1 Polycarbonate substrate 2 Al reflective film 3 Ultraviolet curing resin protective film

Claims (1)

[Claims] A read-only optical recording medium characterized in that the cross-sectional shape of the recording pit in the width direction is wedge-shaped.