JPH02265040A - Optical disk and stamper for manufacturing optical disk - Google Patents

Abstract

PURPOSE:To eliminate a complicated work and to mark a manufacturer's serial number, etc., of an optical disk by forming the mark by allowing a refractive index of a mark part to be different from a refractive index of other part without deforming the disk on its appearance. CONSTITUTION:As for a part in which a mark 2 of an optical disk 1 is put its, appearance is the same as that of other part of the disk, but its refractive index is different. Accordingly, when a monochromatic light is irradiated to the disk 1, an image of the mark 2 is formed on a screen 5 and the mark is discriminated. As for a forming method for the mark, a marking base 11 of a stamper 7 made of nickel is pressed by an elastic limit or below of nickel, a movement of a crystal defect occurs, a residual strain of the stamper is generated, and a mark part is formed. When the optical disk is brought to injection molding by using this stamper, the residual strain of the stamper appears as a difference of the refractive indexes on the disk, and the mark whose external appearance is not varied can be formed on the optical disk 1.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an optical disc on which marks such as a serial number and type are applied, and a stamper used for manufacturing such an optical disc.

(Conventional technology) A method for manufacturing an optical disc will be explained.

After the surface of the glass master disk is precisely polished and further subjected to ultrasonic cleaning, photoresist 1- is evenly applied to the glass master disk and dried.

After writing a signal on the glass master disk using an argon laser beam, the glass master disk is developed, and the portions of the photoresist where the laser beam is on (signal present) are dented.

Next, the glass master disk is placed in an electroforming tank, and nickel electroforming is applied.
Make a stamper. This stamper is placed into an injection machine and a disk is manufactured by injection molding.

For reasons such as manufacturing control, optical discs are marked with serial numbers, serial numbers, and marks that indicate the type of disc.

Marks on the optical disc are formed by forming an uneven mark forming portion 12 on a stamper 10 shown in FIG. 5, and by transferring the unevenness when molding the optical disk by injection molding.

The mark forming portion 12 of the stamper is formed by applying a certain impact force to the stamper with a punch, or by carving irregularities with a knife, sharp raking needle, or the like. Furthermore, a mark forming section 12 is formed on the stamper by a laser processing machine.
Methods such as forming a There is also a method of forming marks by photolithography in the exposure process of a glass master.

(Problems to be Solved by the Invention) However, forming irregularities on the surface of the stamper hinders the flow of resin on the stamper when injection molding a disk. Furthermore, if a knife or the like is used to carve irregularities on the stamper, there is a risk that cutting debris will adhere to the stamper and cause scratches on the disk. Furthermore, when a laser processing machine is used, the work becomes complicated.

(Means for Solving the Problems) The present invention has been made in order to solve the problems of the conventional art described in 2. In an optical disc on which a mark is applied, the mark changes the appearance of the disc. This is an optical disc formed by making the refractive index of the mark portion different from the refractive index of other portions without changing the marking area.

In a stamper for manufacturing an optical disc having a mark forming part for marking an optical disc, the mark forming part is not deformed in appearance but is formed by residual distortion.

(Function) When the optical disc according to claim 1 is irradiated with light, a mark image is formed on a screen or the like that receives transmitted light or reflected light of the irradiated light.

When an optical disc is manufactured using the stamper according to the second aspect of the present invention, the residual distortion of the mark forming portion of the stamper is transferred to the optical disc, and a mark having a refractive index different from that of other portions is formed in this transferred portion.

(Example) Embodiments of the present invention will be described below based on the drawings.

In FIG. 1, reference numeral 1 indicates a compact disc as an optical disc, and a mark 2 is formed on the compact disc 1. This mark 2 represents the serial number, manufacturing number, type, etc. of the compact disc 1.

As shown in FIGS. 1 and 2, the portion of the compact disk 1 marked with mark 3 has no irregularities and has the same appearance as the other portions of the disk, but has a different refractive index. Therefore, when the disc 1 is irradiated with monochromatic light, an image of the mark 3 is formed on the screen 5, and the mark can be identified.

Next, a method for forming marks on an optical disc will be explained.

FIG. 3 shows a stamping stand used to form mark forming portions on the stamper. The base 9 of the marking stand 7 is made of a soft material such as a copper alloy, and the marking portion 11 is made of a hard material such as steel. The height of the marking portion 11 is set to be 1 μm or less.

The stamping stand 11 is pressed against the nickel stamper 7 having a thickness of about 300 μm for 10 minutes at a pressure of about 35 kg/a#, which is below the elastic limit of nickel (36 kg/ad).

Although no plastic deformation occurs in the stamper, residual strain εR occurs within the stamper as shown in FIG.

This residual strain is 0.05% of the thickness of the stamper, that is, 0.15 μm or less.

If a load is applied in the elastic region and this load is removed, the residual strain should be O. If the amount is large, the behavior differs from the above theory.

In other words, by applying pressure for a certain period of time or more to the nickel stamper using the stamping table 7, crystal defects are moved, the crystals are rearranged, residual strain is generated in the stamper, and a mark forming part is formed. will be done.

Using this stamper, the optical disc 1 is made of polycarbonate 1-
When injection molding is performed using acrylic thermosetting resin at a pressure of 350 kg/- or more, the residual distortion of the stamper appears on the disc as an optical property, that is, a difference in refractive index, and although there is no change in the appearance of the optical disc 1, there are marks. 2 will be formed.

When the stamper is as thin as about 300 μm, residual distortion and minute irregularities within the stamper appear on the disk as minute differences in refractive index.

The mark forming portion of the stamper is not limited to being formed on the front surface of the stamper, but can also be formed on the back surface of the stamper. In such a case, the stamping stand 7 is pressed against the back surface of the stamper.

In the above embodiments, the present invention was applied to the Combat I-disk, but the present invention is not limited to this and can also be applied to other optical disks such as magneto-optical disks.

(Effects of the Invention) As described above, according to the present invention, it is possible to form a mark such as a serial number on an optical disc without forming irregularities on the stamper, so that resin is removed when injection molding the optical disc. This eliminates the inconvenience of difficulty in flowing on the stamper.

Further, there is no possibility that cutting debris may adhere to the surface of the stamper and cause scratches on the optical disc, unlike when marks are formed on the stamper by cutting with a knife or the like. Furthermore, there is no need to perform complicated operations unlike when using a laser processing machine.

[Brief explanation of drawings]

FIG. 1 is a diagram showing mark inspection of the optical disc of the present invention, FIG. 2 is a cross-sectional view of the optical disc of the present invention, FIG. 3 is a diagram showing a stamping stand used to manufacture the stamper of the present invention, and FIG.
The figure is a graph showing the relationship between the compressive stress and residual strain of the printing stand when forming mark forming portions on the stamper, and FIG. 5 is a cross-sectional view of a conventional stamper. 1...Disk to Combat 1, 2...Mark, 7.
・Engraving stand

Claims (1)

[Claims] 1. In an optical disc provided with marks, the marks are formed by making the refractive index of the marked portion different from the refractive index of other parts without changing the appearance of the disc. An optical disc characterized by: 2. A stamper for manufacturing an optical disc having a mark forming part for marking an optical disc, characterized in that the mark forming part is formed by causing residual distortion without deforming in appearance.