JPS6079540A - Optical recording medium - Google Patents

Abstract

PURPOSE:To raise poductivity, and also to prevent a protective film from being damaged due to a corner burr by projecting part of the outside circumferential edge of substrate of a recording medium, in the outside diameter direction from the outermost circumference of the surface, and forming a protective a protective layer by extending this projected part. CONSTITUTION:A corner is chamfered so that about a center 1C of the outside circumferential edge of a substrate 1 is projected, for instance, by 0.2mm. in the outside diameter direction from the outermost circumference of one surface having a recording surface 2 of the substrate 1 and the other surface. In case of mold-forming the substrate 1, an undercut 14a is provided on the outside circumference ring 14 of a fixed metallic mold 13. When a depth of this undercut 14a is set to a size corresponding to a molding contraction coefficient of a resin, for instance, 0.2mm., the substrate 1 can be taken out of the metallic molds 11, 13. A metallic reflecting film 5 and a protective film 6 are struck to the upper face of this substrate 1. In this case, the protective film 6 is stuck so as to cover a corner burr 1b and to cover a corner chamfered part 1d. The circumferential edge part of the reflecting film 5 is covered with the protective film 6, and does not touch directly a circumferential atmosphere. Also, when sticking the reflecting film 5, it is unnecessary to use a mask, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical recording medium suitable for use in optical discs such as compact discs, video discs, and optical memories.

BACKGROUND TECHNOLOGY AND PROBLEMS Conventionally, information sources are pits or bumps formed on a transparent substrate, the surface of the secondary pits or bumps is covered with a reflective film, and radiation is applied from the bottom surface of the substrate. A playback device is known in which information is electrically read by a device. A recording medium as shown in FIG. 1 has been proposed as a recording medium for use in this reproducing apparatus. That is, the first
In the figure, (1) is a substrate of a disc-shaped recording medium called a replica, which is made of a transparent resin such as acrylic resin. On the upper surface of this substrate (1), there is formed a recording surface (2) on which a tuning fork, image, sound and image, or other information is formed in a concave and convex shape. The uneven recording portion is formed concentrically or spirally on the substrate (1) so that the recesses are discontinuous. The process of manufacturing the board (11) from the master disc is, as is generally known, by applying electroforming to the recording surface of the master disc to obtain the mother disc.
Electroforming is performed on the recording surface of this mother disk, and the electroformed layer is peeled off from the mother disk to obtain a stamper. The stamper thus obtained, which has a reinforcing layer formed on the back surface of the stamper, is placed in a mold, and the above-mentioned substrate (1) is molded by injection molding or compression molding. Furthermore, the board (1)
A hole (3) for inserting a spindle is formed in the center of the board (1), and the central part of the substrate (1) is a flat part (4) which is continuous with the recording surface (2) and is a non-recording part. There is.

A radiation reflecting film (5) is provided on the upper surface of the substrate (1) configured as described above. This reflective film (5) is made of, for example, Chilminilum and can be deposited, for example, by sputtering or vacuum deposition. In this case, the reflective film (
5) is the recording surface 12) The peripheral part from the light, the central flat part (
4) k is also uniformly deposited. The reflective film (5) applied to the reflective film (5) is extremely thin and easily scratched, so for example, an ultraviolet curing resin is coated flat on the upper surface of the reflective film (5) and then ultraviolet rays are irradiated. harden to form a protective film (
6) is coated. □ In such conventional recording media, Al Ewam is generally used as the reflective film (5), and this reflective □ film (5) extends to the peripheral edge k of the substrate (1). Since the reflective film (5) is exposed to the air, the peripheral part of the reflective film (5) becomes cloudy.
This oxidized part partially peels off from the base M (1), and this peeled part is further oxidized due to moisture, and this part becomes the substrate (1).
There was an inconvenience that this peeling extended to the inner part K.

In view of this, the peripheral edge of the reflective film (5) is prevented from being oxidized, and the reflective film (5) is protected as shown in FIGS. 2 to 4. Kimono has been proposed.

2 to 4 will be explained below. In FIGS. 2 to 4, parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and detailed explanation thereof will be omitted. In this example, a radiation reflecting film is deposited on the upper surface of a molded substrate (1') by sputtering or vacuum deposition, as shown in FIG. Inner circumference m (4a)
A circular mask (7) and a ring-shaped mask (8) are arranged on the outer periphery (1). In the example in FIG.
) is a board product holder (9) with a step so that the stepped rod portion of the board constitutes a ring-shaped mask (8). After that, the aluminum molecules are applied from the direction of the arrow by sputtering or vacuum evaporation, etc. to the third layer.
As shown in the figure, a reflective film (5) is coated on the upper surface 9 of the substrate (1) except for the inner local part (4a) and the outer peripheral part (1a). In other words, from masks (7) and (8) K,
A reflective film is not coated on the inner peripheral part (4a) and the outer peripheral part (1a) of the substrate (1). Next, as shown in Fig. 4, for example, an ultraviolet curable resin is applied in a flat manner to the top surface of the substrate (1) on which the reflective film (5) of Te is applied. This is cured by irradiation with ultraviolet rays and a protective film (6) is applied. In this case, as is clear from FIG. 4, the protective film (6) is directly applied to the inner circumference (4a) 7 and outer circumference (1a) of the substrate (1), and the reflective film tube) Since the peripheral edge of is not covered by the protective film (6) K, the reflective film (5) of and 7 is not directly exposed to the air.

Such a recording medium does not have a reflective film (5) applied to the inner peripheral part (4a) and outer peripheral part (1a) of the substrate (1), but instead has a protective film.

(6) by dropping the periphery of this 5 reflective film (5) onto the substrate (
1) Since the reflective film (51) is coated, the peripheral edge of the reflective film (51) is securely coated, and if the reflective film (5) is directly exposed to air, it will not be sharpened. ) can protect this reflective film (5) without the risk of oxidation.

However, in the examples in Figures 2 to 4, the circular mask (
7) and a ring-shaped mask (8) are required, which increases the number of man-hours and reduces productivity.

Also in the above embodiment, when the substrate (1) is formed into a mold, the moving metal is used as shown in FIG. 31 (1 m) K stamper az is arranged, and the board (1) is stamped with the stamp provided with this movable mold (1 m) K, and the outer ring (14) provided on the pannier a'4h fixed metal 11 (13). The molding cavity haze is flattened, and this cavity (for example, 19KQ, since acrylic resin is injected and molded, the straining force is 1, and this stun <
- There is a bartending surface ae between a3 and the outer ring a, which generally causes a corner burr (lb) on the molded product of the substrate (1) as shown in Figure 6.
Part 1b) is easy to get caught, and in this corner part 9 (1b)
) The strength of the protective film (6) is weak, and the protective film (6) is short-lived.
6) is easily damaged, and when the -44 film (6) is damaged, the reflective film (5) will come into direct contact with the surrounding atmosphere and the Sorimachi film (5) will be eroded.

OBJECTS OF THE INVENTION In view of the above, an object of the present invention is to improve productivity and prevent damage to the protective film.

Summary of the Invention The present invention provides an optical recording device comprising a substrate having one surface having a signal portion and another surface thereof, a metal reflective film covering the signal portion, and a protective layer protecting the metal reflective film. In the medium, at least a part of the outer periphery of the substrate projects in the outer radial direction from the outermost periphery of this one surface, and the protruding portion of the protective layer is extended, and the present invention According to.

Productivity is improved because it can be manufactured without the need for masks, etc., and even if there are corner burrs, the outer periphery of the board is small (partially protruding in the outer radial direction from the outermost periphery of one surface). There is an advantage that damage to the protective film can be improved.

EXAMPLE Hereinafter, an example of the optical recording medium of the present invention will be described with reference to FIGS. 7 and 8. This figure 7 and 8
In the drawings, parts corresponding to those in FIGS. 1 to 6 are designated by the same reference numerals, and detailed explanation thereof will be omitted.

In this example, as shown in FIG.
For example, 0.2 iom in the outer radial direction from the outermost periphery of one surface having the signal portion (1), that is, the recording surface (2), and the outermost periphery of the other surface.
So-called corner chamfering is performed to make it protrude.

When molding the thick root (1) according to this example, the eighth
As shown in the figure, in the mold in Fig. 5, the fixed mold a9
4) An IC undercut (14a) is provided around the outer circumferential ring α4). The depth of this undercut (14a) is set to a size commensurate with the molding shrinkage rate of the resin, for example, 0.2 mm. In this way, the product, i.e., the substrate (11) is separated from the mold (1
1) (Easy to take out from 13+.

The metal reflective film (5) and the protective film (6) are deposited in the same manner as in the example shown in FIG. In this case, the protective film (6) is a corner burr (1
b) Cover the corner chamfer up to 7m (ld).

Since the recording medium according to this example is constructed as described above, radiation is irradiated from the back surface of the substrate (1) in the same way as in the conventional case, and the radiation reflected from the reflective surface (5) is converted into an electrical signal by the optical-to-electrical converter. information signals can be read. In addition, in this example, the protective film (6) was provided so as to cover the corner chamfered portion (ld) of the base & (1), so the peripheral edge of the reflective film (5) was covered by the protective layer (6)k. , this reflective film (5) does not come into direct contact with the surrounding atmosphere.

Further, in this example, since no mask or the like is used to deposit the reflective film (5), the number of steps is reduced (and productivity can be improved accordingly).

Furthermore, in this example, the approximately central portion (IC) of the outer periphery of the substrate (1)
The mold (I
I) Even if a corner burr (1b) is produced on the outermost periphery of this one surface due to the parting rotation of α3, this corner burr (1b) is located inside the outermost periphery (IC) of the substrate (1), so Even if an object comes into contact with the outer periphery of this substrate (1) during handling, it will not come into contact with this corner burr (1b), so there is an advantage that the protective film (6) on this corner burr (1b) will not be damaged. be.

In the above-mentioned embodiment, approximately the center of the outer periphery of the substrate (1) (IC
) is described as protruding in the outer radial direction, but this shape is not limited to the above example. Of course, if the number 5 is made to protrude, the same effect as described above can be obtained.

Furthermore, the present invention is not limited to the above-described embodiments; it goes without saying that various other configurations may be adopted without departing from the gist of the present invention.

Effects of the Invention According to the present invention, since a mask or the like is not required for depositing the substrate (111c reflective film (5)), productivity is improved and at least a portion of the outer periphery of the substrate (1) is coated. Since it protrudes in the outer radial direction from the outermost periphery of one surface having the signal portion, there is an advantage that damage to the protective film (6) can be prevented even if there is a corner burr (1b).

[Brief explanation of the drawing]

1 and 4 are cross-sectional views showing examples of conventional optical recording media, FIGS. 2 and 3 are cross-sectional views showing the manufacturing process of the example shown in FIG. 4, and FIG. 5 is a cross-sectional view showing examples of conventional optical recording media. FIG. 6 is a partially enlarged sectional view of the example shown in FIG. 4, and FIG. 7 is a part of an embodiment of the optical recording medium of the present invention. The enlarged sectional view, FIG. 8, is a partially cutaway sectional view showing an example of the mold used in manufacturing the example shown in FIG. (1) is a disk-shaped substrate, (IC) is the center part of the outer periphery, (l
d) is a corner chamfered portion, (2) is a recording surface, (5) is a reflective film, and (6) is a peritoneal retention film. 1st factor 1ko Fig. 2 2 Fig. 8 4th factor ' Fig. 6 1st factor

Claims (1)

[Scope of Claims] An optical recording medium comprising a substrate having one surface having a signal portion and the other surface thereof, a metal reflective film covering the signal portion, and a protective layer protecting the metal reflective film. At least the outer periphery of the substrate. A part of the above-mentioned surface is made to protrude in the outer radial direction from the outermost periphery of the surface,
An optical recording medium characterized in that the protective layer is formed to extend on the protruding portion.