JPH09161333A - Device for forming light transparent layer of optical disk and method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to rapidly form a light transparent layer covering the signal surface of an optical disk with good accuracy. SOLUTION: While a substrate 2 is kept rotated, a liquid UV curing resin 16 is dropped near the center of the signal surface 4 thereof and is supplied to an annular form. The substrate 2 is rotated to diffuse the UV curing resin 16 over the entire part from the central side toward the outer peripheral side by the centrifugal force generated by the rotation. The UV curing resin 16 diffused over the entire part from the central side toward the outer peripheral side is irradiated with UV spot light from the central side to the outer peripheral side of the rotating substrate, by which the UV curing resin is successively cured to a prescribed thickness from the central side to the outer peripheral side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and method for forming a light transmitting layer in a novel optical disc. More specifically, the present invention relates to a technique for accurately forming a light transmission layer that covers a signal surface of an optical disc in a short time.

[0002]

2. Description of the Related Art FIG. 1 shows the structure of an optical disc 1.

Pits (representing a signal by unevenness) 3 are formed on one surface of a transparent substrate 2 formed of a transparent synthetic resin, for example, a polycarbonate resin,
A surface (hereinafter referred to as "signal surface") 4 on which the pits 3 are formed is covered with a reflective film 5 made of aluminum or the like. The reflective film 5 is covered with a transparent protective light transmission layer 6.

Then, the optical pickup is adapted to receive the laser light emitted from the optical pickup and reflected by the reflection film 5 to read the pits 3.

[0005]

Conventionally, signal reading by an optical pickup is performed by irradiating laser light from the substrate 2 side (see FIG. 2).

By the way, with the increase in recording density of optical discs, the influence of substrate warpage cannot be ignored. The influence of the warp of the medium in which the laser light advances can be made smaller as the thickness of the medium becomes thinner, but normally the thickness of the substrate 2 is about 1.2 mm, and it is not possible to make it as thin as about 0.6 mm. It is possible, but it is technically difficult to make it thinner.

Therefore, it is conceivable to irradiate the laser beam from the side of the light transmitting layer 6 formed so as to cover the signal surface 4 (see FIG. 3). Conventionally, the surface of the light transmitting layer 6 is uniform. In addition, there is a possibility that accurate signal reading and / or writing cannot be performed.

Therefore, an object of the present invention is to make it possible to form a light transmitting layer that covers a signal surface of an optical disc with high precision and in a short time.

[0009]

In order to solve the above-mentioned problems, an apparatus for forming a light-transmitting layer in an optical disc of the present invention comprises a substrate rotating means for rotating a substrate and a signal of the substrate rotated by the substrate rotating means. Ultraviolet curable resin supply means for dropping liquid ultraviolet curable resin near the center of the surface and supplying it in a ring shape, and irradiating ultraviolet rays to the ultraviolet curable resin distributed so as to cover the signal surface by centrifugal force due to rotation of the substrate. It is provided with an ultraviolet ray supplying means for curing,
The method of forming the light transmitting layer in the optical disc of the present invention comprises the steps of dropping a liquid ultraviolet curable resin near the center of the signal surface while rotating the substrate and supplying the liquid in an annular shape, and ultraviolet curing in an annular shape near the center of the signal surface. The step of rotating the substrate to which the resin is supplied and diffusing the ultraviolet curable resin entirely from the center side to the outer peripheral side by the centrifugal force due to the rotation, and the ultraviolet ray to the ultraviolet curable resin totally diffused from the central side to the outer peripheral side Is applied to cure the ultraviolet curable resin to a predetermined thickness.

Therefore, according to the present invention, the substrate is rotated, and the liquid ultraviolet curing resin, which is annularly supplied near the center by the centrifugal force, is diffused so as to cover the entire signal surface,
Since it is irradiated with ultraviolet rays to cure it to a predetermined thickness,
The light transmission layer covering the signal surface can be formed with high precision, that is, without unevenness on the surface and with a uniform film thickness, and in a short time.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of an apparatus and method for forming a light transmitting layer in an optical disc of the present invention will be described below with reference to the accompanying drawings. In the following description, the light transmission layer 6 in the read-only optical disc 1 is formed.

Device 7 for forming a light transmitting layer in an optical disk
Has a motor 9 supported on the machine base 8, and the output shaft 9 of the motor 9
a extends upward. A substrate mounting table 10 is fixed to the upper end of the motor output shaft 9a, and the substrate 2 is supported on the upper surface of the substrate mounting table 10 with the signal surface 4 facing upward. The motor 9, the output shaft 9a, and the substrate mounting table 10 constitute a substrate rotating means.

An ultraviolet curable resin supplier 12 having a resin supply nozzle 11 as an ultraviolet curable resin supply means for supplying liquid ultraviolet curable resin onto the signal surface 4 of the substrate 2 is provided above the machine base 8. There is. The resin supply nozzle 1
1 is positioned so as to point to a position slightly deviated from the rotation center of the substrate mounting table 10.

Further, as an ultraviolet ray supplying means for irradiating the ultraviolet ray spot light to the liquid ultraviolet ray curable resin supplied so as to cover the signal surface 4 of the substrate 2 supported on the substrate mounting table 10 above the machine table 8. A UV irradiator 14 having a UV nozzle 13 is arranged. Then, the UV irradiator 14 moves from a position where the UV nozzle 13 is directed near the center of the substrate 2 supported on the substrate mounting table 10 to a position where it is directed outside the outer periphery of the substrate 2. Has been made possible.

A method of forming the light transmission layer 6 covering the signal surface 4 of the substrate 2 by using the light transmission layer forming device 7 of the optical disk will be described below.

First, the substrate 2 is placed on the substrate platform 10 with the signal surface 4 facing up (see FIG. 5). Then, the resin supply nozzle 11 is positioned so as to direct the boundary portion 15 between the inner peripheral edge of the reflective film 5 and the central portion of the substrate. When the ultraviolet curable resin supply device 12 is fixedly provided, the resin supply nozzle 11 directs the boundary portion 15 when the substrate 2 is mounted on the substrate mounting table 10. It will be.

Next, the motor 9 is driven to drive the substrate mounting table 1
0, that is, while rotating the substrate 2 at a low speed, the ultraviolet curable resin 16 is dropped from the resin supply nozzle 11 to supply the ultraviolet curable resin 16 in an annular shape on the boundary portion 15 (see FIG. 6).

Then, the substrate 2 is rotated at a high speed and a centrifugal force is applied to the ultraviolet curable resin 16 supplied in the above annular shape, so that the ultraviolet curable resin 16 goes from the central portion to the outer peripheral portion in the entire area of the signal surface 4. It is diffused so as to extend (see FIG. 7).

Then, the UV irradiator 14 is moved to move U
The V nozzle 13 is directed toward the inner peripheral edge of the ultraviolet curable resin 16 diffused so as to cover the entire signal surface 4, and the ultraviolet spot light 1 is emitted from the UV nozzle 13 while rotating the substrate 2.
7 is irradiated to cure the ultraviolet curable resin 16. That is,
The UV curable resin 16 is layered by moving the UV nozzle 13 from the inner peripheral side to the outer peripheral side of the ultraviolet curable resin 16.
Is sequentially cured from the inner peripheral side to the outer peripheral side (see FIG. 8). At this time, the ultraviolet curable resin 16 is cured in a state where the layer has a predetermined thickness. For this purpose, if the film to be cured next is thin,
The rotation speed of the substrate 2 is reduced to weaken the centrifugal force acting,
On the contrary, if the film thickness is thick, it is advisable to cure the substrate 2 from the point where the film thickness appears, while controlling the rotation speed of the substrate 2 to increase the centrifugal force that acts.

As described above, by appropriately selecting various conditions such as the amount of the ultraviolet curable resin 16 to be dropped, the rotation speed of the substrate 2, etc., the signal surface 4 can be covered thinly (0.1 to 0.2 m).
m) and the light transmitting layer 6 having a uniform film thickness over the entire surface can be efficiently formed.

In the above-mentioned embodiment, the ultraviolet curing resin is irradiated with ultraviolet spot light from the inner peripheral side to the outer peripheral side. However, this is not a spot type one. Alternatively, for example, the entire surface of the ultraviolet curable resin may be irradiated with ultraviolet rays using a surface irradiation type ultraviolet irradiation device.

In the above example, the read-only optical disc 1 is used.
Although the case where the light transmission layer is formed in the above is described, it is needless to say that the present invention can be applied to the formation of the light transmission layer of a readable / writable optical disc.

[0023]

As is apparent from the above description, the apparatus for forming the light transmitting layer in the optical disc of the present invention is
Substrate rotating means for rotating the substrate, ultraviolet curable resin supply means for dripping liquid ultraviolet curable resin in the vicinity of the center of the signal surface of the substrate being rotated by the substrate rotating means and supplying it in an annular shape, and centrifugal force due to rotation of the substrate And an ultraviolet ray supplying means for irradiating and curing the ultraviolet ray curing resin which is distributed so as to cover the signal surface. The step of dropping the liquid ultraviolet curable resin near the center of the signal surface and supplying it in a ring shape, and rotating the substrate on which the ultraviolet curable resin is supplied in an annular shape near the center of the signal surface, and by the centrifugal force due to the rotation. The step of diffusing the UV curable resin from the center side to the outer circumference side and the UV curing resin that has been diffused from the center side to the outer circumference side by irradiating UV light The resin and a step of curing a predetermined thickness.

Therefore, according to the present invention, the substrate is rotated, and the liquid ultraviolet curable resin which is circularly supplied near the center by the centrifugal force is diffused so as to cover the entire signal surface,
Since it is irradiated with ultraviolet rays to cure it to a predetermined thickness,
The light transmission layer covering the signal surface can be formed with high precision, that is, without unevenness on the surface and with a uniform film thickness, and in a short time.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing the structure of an optical disc with the thickness of each portion emphasized.

FIG. 2 is a diagram showing one method of signal reading.

FIG. 3 is a diagram showing another signal reading method.

FIG. 4 is a vertical sectional side view showing an outline of a light transmission layer forming apparatus.

FIG. 5 is a schematic view showing a method of forming a light transmitting layer in an optical disc according to the present invention, together with FIGS. 6 to 8, and showing a state in which a substrate is placed on a substrate placing table.

FIG. 6 shows a step of annularly supplying an ultraviolet curable resin onto a substrate.

FIG. 7 shows a step of diffusing an ultraviolet curable resin over the entire signal surface.

FIG. 8 shows a step of irradiating the ultraviolet curable resin diffused over the entire signal surface with an ultraviolet spot light.

[Explanation of symbols]

1 Optical Disc 2 Substrate 4 Signal Surface 6 Light Transmission Layer 7 Light Transmission Layer Forming Device 9 Motor (Substrate Rotating Means) 9a Output Shaft (Substrate Rotating Means) 10 Substrate Placement Table (Substrate Rotating Means) 12 UV Curing Resin Supply Machine (UV Curing) Resin supply means) 14 UV irradiator (ultraviolet light supply means) 16 Liquid ultraviolet curing resin 17 Ultraviolet spot light

Claims (4)

[Claims] 1. A device for forming a light-transmitting layer covering a surface of a substrate on which a signal is formed (hereinafter referred to as “signal surface”), the substrate rotating means rotating the substrate, and the substrate rotating means. UV-curing resin supply means that drips liquid UV-curing resin near the center of the signal surface of the substrate being rotated and supplies it in an annular shape, and the ultraviolet rays that are distributed so as to cover the signal surface by the centrifugal force due to the rotation of the substrate. An apparatus for forming a light-transmitting layer in an optical disk, comprising: an ultraviolet ray supplying means for irradiating a cured resin with ultraviolet rays to cure the resin. 2. The ultraviolet light supplying means is for irradiating the ultraviolet spot light and moving the ultraviolet spot light from the center side to the outer peripheral side of the substrate.
An apparatus for forming a light-transmitting layer in the optical disc according to [4]. 3. A method of forming a light transmission layer covering a signal surface of a substrate, the method comprising: dropping a liquid ultraviolet curable resin near the center of the signal surface while rotating the substrate and supplying the liquid in an annular shape. Rotating the substrate on which the UV curable resin is supplied in an annular shape near the center of the signal surface and spreading the UV curable resin from the center side to the outer peripheral side by centrifugal force due to the rotation, and from the center side to the outer peripheral side And a step of irradiating the ultraviolet curable resin diffused over the whole surface with ultraviolet rays to cure the ultraviolet curable resin to a predetermined thickness. 4. The step of irradiating the ultraviolet curable resin with ultraviolet rays is performed by moving the ultraviolet spot light from the center side to the outer peripheral side of the substrate which is rotating on the ultraviolet curable resin diffused all over from the central side to the outer peripheral side. 4. The method for forming a light transmitting layer in an optical disc according to claim 3, wherein the ultraviolet curable resin is sequentially cured from the center side to the outer peripheral side by irradiation so as to have a predetermined thickness.