JPH0249493B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an optical recording and reproducing disk, and particularly to the shape of the outer peripheral edge of the disk. Conventionally, optical recording disks have been produced through a process of forming a recording layer that can be optically recorded and reproduced on a circular plastic plate, and then overlapping another plastic plate as necessary to protect the recording layer. was common. The problem with this conventional method is that the surface of the plastic plate used to protect the recording layer becomes scratched due to contact with dust or foreign matter during manufacturing. This is also becoming a problem for optical recording and reproducing discs that use laser light. That is, the problem was that this appeared as noise in recorded and reproduced signals. In contrast, the present inventors developed an optical recording disk manufactured by a conventional method using the
It has been found that by coating and curing the coating compositions disclosed in JP-A-56-22364 and JP-A-56-135526 to form a transparent hard film, a remarkable scratch-preventing effect can be obtained. Although this method has made handling the disk very easy, it is also assumed that the disk may be placed on a desk, shelf, etc., and in such cases it is highly likely that it will come into contact with indoor dust, etc. . Therefore, the inventors of the present invention have created a disk in which the inside is less likely to come into contact with dust by providing a convex portion on the outer peripheral edge as described above, which is highly effective in preventing scratches when stacking and handling the disks, and by floating the inside of the disk. I came to invent it. An embodiment of the present invention will be described below with reference to FIGS. 1 to 3. The optical recording/reproducing disk substrate used in the present invention is mainly composed of three layers as shown in FIG. That is, a recording layer 2 necessary for optical recording and reproduction is formed between two acrylic plates 1 having a diameter of 210 mm and having a hole in the center. More specifically, this recording layer 2 utilizes the principle of causing a phase transition by irradiation with laser light and changing the reflectance of the layer. The coating material 3 was applied to the outermost edge of the disk formed from the acrylic plate 1 and the recording layer 2 in the shape shown in FIG. 2 and cured. The height l between the inner circumferential surface of the effective recording and reproducing surface and the convex portion provided at the outer circumferential edge is preferably as high as possible, but if it is too high, not only will the aesthetic appearance be lost, but also the positional relationship with the laser head and other points will be affected. It is preferably about 200μ or less. Also, below 10μ,
No significant effect was observed on scratches caused by sand and dust. In Fig. 3, the idea in Fig. 2 is further advanced, and the entire disk is coated and has a convex portion at the end. A convex shape can be obtained. It is preferable that both width and height have the same dimensions and shape as those considered in FIG. The example shown in Figure 2 was painted by hand.
This was done by adjusting the coating material viscosity with a solvent. The example shown in FIG. 3 could be obtained by the following coating method. That is, a dip tank was filled with a coating liquid, and the coating material was simultaneously applied to both surfaces of the resin disk while rotating it around the rotation shaft at the center of the disk. While the resin disk was rotated using the same rotation axis as during coating, it was simultaneously cured using ultraviolet light emitted from an ultraviolet lamp and a reflecting mirror. For more details, please refer to the patent application filed in 1983 by the present inventors.
The method described in No. 142062 was followed. Also, the third
By changing the chamfer angle in Figure B from 10 degrees to 80 degrees, the coating liquid viscosity was adjusted to 5 cps - 30 cps (B type viscometer 20
By varying the temperature up to 10° C.), disks with the desired heights shown in Table 1 were obtained. To determine the scratch prevention effect, place the
Spread sand of 300μ or less and use the disk's own weight to cover it.
The flaws caused by 10 reciprocations were checked visually and with a step gauge. The discrimination rank is as follows:
(Practical values are A, B, and C) A: No flaws B: A few shallow flaws (no effect on the signal) C: A few deep flaws (the signal may be affected depending on the position of the flaw) D: Innumerable Shallow flaws E: Numerous deep flaws F: Other defects (appearance, etc.)

[Table] From the above results, by providing a convex portion of 10 to 200 μm on the outer circumferential edge of the disk, it is possible to provide a practical disk that is less prone to scratches in the disk recording and reproduction area.

[Brief explanation of drawings]

FIG. 1 is a side view of an optical recording/reproducing disk according to an embodiment of the present invention, and FIGS. 2 and 3 are partial sectional views of the outer peripheral end of one embodiment and another embodiment of the same disk, respectively. . 1... Acrylic board, 3... Coating material.

Claims (1)

[Claims] 1. In an optical recording and reproducing disk in which a recording layer capable of optically recording and reproducing is formed between a pair of circular plastic plates serving as a protective layer, a layer is formed on the outer peripheral edge of the disk from the inner peripheral surface of the effective recording and reproducing surface. An optical recording/reproducing disk formed with a coating film having convex portions 10 to 200μ higher.