JPH10106036A - Disk and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control an adhesive layer or a UV resin layer to have a prescribed thickness without complicated control by incorporating a fine particle base material having a particle diameter corresponding to the prescribed thickness in the adhesive layer or the UV resin layer. SOLUTION: Two layer of recording surfaces 3, 3 are formed on a disk 1 and each recording surface is read by laser beam. The adhesive layer 5 is required to have a prescribed thickness to stably read each recording surface. In such a case, the thickness of the adhesive is set to 55±15μm. As the adhesive layer, the UV resin is used and high precise 'Unibeads (R)' of the fine particle base material is previously incorporated thereinto. The high precise 'Unibeads (R)' is a glass fine particle having 40μm particle diameter, in almost spheroidal form and has remarkably excellent fluidity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk formed by bonding a plurality of disk substrates with an adhesive layer having a predetermined thickness to form one disk, and a UV resin layer having a predetermined thickness on which information is recorded on the surface of the disk base. And a method of manufacturing these disks.

[0002]

2. Description of the Related Art At present, as for a disk to be read by a laser beam, a disk having a plurality of recording surfaces on one disk has been proposed. Such a disk is formed by bonding two disk substrates having a recording surface with an adhesive or by further thinning a U-shaped substrate on the surface of a disk substrate having a recording surface.
It is manufactured by forming the recording surface of the V resin layer. The adhesive layer and the UV resin layer of these discs are required to have a predetermined thickness so that they can be stably read by laser light.

In forming the above-mentioned adhesive layer having a predetermined thickness, the thickness of the disk substrate to be bonded is measured in advance, the adhesive is applied, the disks are superposed, and if the total thickness of the disk is measured, the predetermined thickness is obtained. There has been proposed a method in which the pressure is increased until the thickness is reduced. U of predetermined thickness
Regarding the formation of the V-resin layer, a method has been proposed in which the thickness of the stamper and the disk substrate is measured in advance, and the total thickness is measured and the pressure is increased to a predetermined thickness.

[0004]

In the above-mentioned conventional disk manufacturing method, since the thickness of each disk substrate varies from one to another, the thickness of all disk substrates must be measured. Further, since high-precision control must be performed even during pressurization, a high-precision press and a control device are required, and there are problems in cost and manufacturing efficiency. An object of the present invention is to provide a disk of this kind which does not require cost for manufacturing equipment and has excellent manufacturing efficiency, and a method for manufacturing the same.

[0005]

SUMMARY OF THE INVENTION The present invention provides an adhesive or U.S.A.
This is a disk and a method for manufacturing a disk in which a predetermined thickness of an adhesive layer or a UV resin layer is ensured by mixing a fine particle material such as glass having a particle diameter corresponding to a predetermined thickness into a V resin. Fine material is transparent to laser light, adhesive or UV
It is preferable that the refractive indexes of the resin and light are close to each other, and that the shape of the particles is closer to a sphere. At present, glass fine particles are the most suitable, but such particles may be used in the future if resin fine particles are produced at low cost.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to embodiments. 1 and 2 relate to a disc 1 in which two disc substrates 2 are bonded and integrated with an adhesive layer 5. FIG. 1 is an explanatory view of the adhesive layer, and FIG. 2 is a sectional explanatory view of the disc 1.

[0007] As shown in FIG. 2, the disc 1 has two layers of recording surfaces 3, 3, each of which is read by laser beams 6, 6. In order to read each recording surface stably, the adhesive layer 5 is required to have a predetermined thickness. In the case of this embodiment, the thickness of the adhesive layer 5 is 55
It is defined as ± 15 μm.

The disk substrates 2, 2 are manufactured by injection molding or the like, and each has a recording surface 3 on each side of which a minute recording pit is formed. Minute recording pits have a width of 0.5
μm and a depth as small as about 0.1 μm, which are considerably enlarged in the drawings.

As the adhesive, a UV resin is used, and high-precision unibeads (trade name), which is a fine-grained material, is mixed in advance. This high precision uni-bead has a particle size of 40 μm
Glass particles, each of which has a substantially spherical shape, and is extremely excellent in fluidity. The mixing ratio is preferably the ratio of the high-precision unibeads 1 to the UV resin 500 in terms of weight ratio, but this ratio can of course be increased or decreased as necessary.

An adhesive mixed with a fine-grained material is applied to a disk substrate by an appropriate method, the other disk is bonded, an adhesive layer is formed, and both disk substrates are bonded and integrated. The most common method is to drop an adhesive in a donut ring shape on the upper surface of one disk substrate, place the other disk substrate on top of it, and apply pressure to diffuse the adhesive and form an adhesive layer Is the way. The adhesive is spread thinly,
As shown in FIG. 7, the thickness finally becomes close to the particle size of the fine material 4. Alternatively, an adhesive can be applied by a spin coating method, a printing method, or the like. In the case where the film is thinly applied in advance, the pressing step is not always necessary. The finer the material, the closer the particles are to a spherical shape, the better the fluidity, and the fine material is diffused without overlapping as shown in FIG. It is suitable that the particle size of the fine material is slightly smaller than the desired thickness of the adhesive layer as in this embodiment.

FIGS. 3 and 4 relate to a disk 10 having a recording surface formed by a thin UV resin layer according to another embodiment.
FIG. 3 is an explanatory view of the UV resin layer, and FIG. 4 is an explanatory sectional view of the disk 10.

As shown in FIG. 4, the disk 10 has four recording surfaces 13, 13, 14, and 14, and the recording surfaces 14, 14 are formed of a thin UV resin layer. Each recording surface is read by the laser beam 19, but in order to read the recording surface of each layer stably,
It is required that the UV resin layer has a predetermined thickness. The disk 10 is manufactured by bonding and integrating two disk substrates 12, 12 with an adhesive layer 17.

The disk substrate 12 is manufactured as follows. First, the recording surface 1 on which a minute recording pit is recorded on one side
The disk substrate 11 having 3 is formed by usual injection molding or the like. Next, U is applied to the recording surface 13 or the stamper 18 of the disk base material 11 by a so-called 2P molding method.
V resin is applied, and as shown in FIG. 3, the UV resin layer 16 on which the recording pits of the stamper 18 are further transferred is formed on the surface of the recording surface 13. In the case of the present embodiment, the thickness of the UV resin layer 16 is set to 55 ± 15 μm.

Prior to the application of the UV resin, a fine particle material 15 is mixed in the UV resin in advance. Fine material 15
Is glass fine particles having a particle size of 40 μm as in the above-described embodiment, and the mixing ratio is also 1/500 in weight ratio.

Also in this embodiment, the thickness of the UV resin layer becomes close to the particle size of the fine-grained material 15 by the same operation as the above-mentioned embodiment.

[0016]

According to the present invention, the thickness of the adhesive layer or the UV resin layer can be set to a predetermined thickness without complicated control, so that the cost of the manufacturing apparatus can be reduced,
Manufacturing efficiency can also be increased.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an adhesive layer 5 of a disk 1.

FIG. 2 is an explanatory sectional view of the disk 1.

FIG. 3 is an explanatory diagram of a UV resin layer 16 of the disk 10.

FIG. 4 is an explanatory sectional view of the disk 10;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Disk 2 Disk substrate 3 Recording surface 4 Fine material 5 Adhesive layer 6 Laser beam 10 Disk 11 Disk base material 12 Disk substrate 13 Recording surface 14 Recording surface 15 Fine material 16 UV resin layer 17 Adhesive layer 18 Stamper 19 Laser light

Claims (8)

[Claims] 1. A disk comprising a plurality of disk substrates bonded and integrated via an adhesive layer, wherein a large number of fine particles having a particle size corresponding to a predetermined thickness are mixed into the adhesive layer. 2. The disk according to claim 1, wherein the fine material is fine particles of glass. 3. The disk according to claim 1, wherein the fine material is fine particles of a synthetic resin. 4. A method for manufacturing a disk in which a plurality of disk substrates are bonded and integrated via an adhesive layer, wherein the adhesive has a particle size corresponding to a predetermined thickness of the adhesive layer before the adhesive is applied to the disk substrate. For producing a disk, comprising a step of mixing fine material 5. A disk having a recording surface formed by a thin UV resin layer, wherein a large number of fine particles having a particle size corresponding to a predetermined thickness are mixed in the UV resin layer. 6. The disk according to claim 5, wherein the fine material is glass fine particles. 7. The disk according to claim 5, wherein the fine material is fine particles of a synthetic resin. 8. A method for manufacturing a disk having a recording surface formed of a thin UV resin layer, wherein a fine particle material having a particle size corresponding to a predetermined thickness of the UV resin layer is previously mixed into the UV resin before applying the UV resin. Method for manufacturing a disc, comprising the steps of: