JPS58199451A - Manufacture of optical information recording medium - Google Patents

Abstract

PURPOSE:To obtain an optical disk with an excellent S/N by bringing a substrate provided with a photosensitive film into contact fixedly with a substrate provided with a reflective film on a survo trck surface. CONSTITUTION:The photosensitive film 2 of organic coloring matter is formed on a substrate 1 by spin coating method. A spiral or concentric servo tracks 8 are provided on a substrate 4 and the metallic reflective film 3 is formed on its surface by vacuum deposition. Those substrates 1, 4 are fixed together in contact to form an optical disk.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical recording medium for optically reproducing information by wire. □ In recent years, technology has been developed to record and reproduce audio, video, information, etc. at high density by irradiating a disk-shaped recording medium with a laser beam that focuses on microscopic fish collection, and various devices and media have been proposed. stone. These are recorded when a recording film such as a metal film or a dye film formed on a substrate undergoes physical changes such as unevenness or optical changes such as light reflectance, transmittance, and polarization when irradiated with laser light. It is reproduced optically.

However, when using a mechanical tracking method to perform recording and reproduction at a track pitch of several micrometers by irradiating a focused laser beam while rotating this internal disc-shaped optical recording medium, advanced circumscribing techniques are required. As a result, recording equipment becomes complicated.

To date, various proposals have been made to eliminate this drawback, but among them is a method of optically performing tracking servo by providing a spiral or concentric servo track on the board. There is. However, since the photosensitive film made of organic dye is used as a servo tracer in the form of a surface pattern, when spin coding is performed on the substrate, the surface condition of this photosensitive film is very poor and the film thickness is uneven, resulting in recording tracks. The accuracy of detecting deviation from the original position is poor. A reflective film of M is deposited on a substrate having a servo track of a plane image and a flat substrate, respectively, and a photosensitive film of an organic dye is formed thereon by spin ′:1′-) to transmit a signal. When I recorded and played back the two and compared the two, I found that the information recorded by the unevenness of the servo track in the previous book.
Photosensitivity of ``film surface'' □ The film thickness is wooden and the surface precision is poor, so the bit shape is rough. Signal：：：：：ni′：
2:::″””′°”′For this purpose, an optically transparent coating layer is spin-coded on a substrate having spiral or concentric servo tracks to the extent that the unevenness is filled. A method of providing a photosensitive film thereon is also being considered.

However, even with the photosensitive film formed in this way, depressions remain on the surface along the servo track grooves. Therefore, in order to obtain a flat surface with negligible effects during recording, it is necessary to use this optical Apply a transparent coating layer to a very thick layer (1 μm).
In this case, the detection sensitivity of the tracking servo signal was reduced.

The present invention was made in order to eliminate these drawbacks, and involves forming a photosensitive film on the flat 4 substrate side, providing a spiral or concentric servo track on the protective layer side, and attaching a reflective film. , is characterized by the fact that the two are brought into close contact with each other.

An embodiment of the present invention will be explained below with reference to the drawings.〇 In Fig. 1, the first substrate is made of an optically transparent and flat acrylic resin with a thickness of L 2 m, polycarbonate, polyethylene, polyester. , polyurethane, polystyrene, vinyl chloride, or other resins or st
A photosensitive film (2) of an organic dye was formed on a substrate (1) made of an inorganic material such as ow using a spin coding method.

AI SA is applied to the protective layer (4) as the second substrate made of resin such as polyethylene, polyester, polyurethane, polystyrene, vinyl chloride, or inorganic material such as stow.
u −, AJi' % Sakai film (
3) is formed into a film by a vacuum evaporation method to form the photosensitive film (2).
A circular disk-shaped recording medium as shown in FIG. 1 was prepared by adhering the disk at the central or peripheral portions of the disk where recording and reproduction are not performed.

The recording medium thus prepared is irradiated with a laser beam (7)' perpendicularly from the substrate (1) side, and a tracking servo is applied to the photosensitive film portion facing the hollow portion (5) so that recording and reproduction can be performed. conduct. Tracking detection is performed by reading the phase difference of laser beams reflected from each of the concave and convex portions of the protective film (4). The relationship between the phase difference of the reflected light from the four convex portions and the phase depth a of the servo track groove 9 is expressed by the following formula (%) (2). (λ: wavelength of the laser beam, n: refractive index of the gas in the hollow part) The laser beam passes through the hollow part and is reflected by the protective layer and the recesses, and the laser beam does not pass through the hollow part and is reflected by the convex parts. Determine the phase depth of the servo track grooves so that the 0 phase difference interferes with each other (2”/2
), and if the refractive index of the gas (air) in the hollow part is 'fr1, then a is (λ/4) from equation (4), and the phase depth of the servo track groove is 0.1 to 0.3 am)? A recording bit (6) model recorded using the determined 0 laser is shown in FIG.

In this example, since there is a Hiro servo track, tracking servo is easy, and since the photosensitive film is flat, the shape of the recording pit is good and the signal-to-noise ratio is high. Since the hollow portion is made of air with a low temperature, it also has the effect that recording sensitivity does not decrease.

As explained above, according to the present invention, since the photosensitive film of the circular disk-shaped recording medium is optically flat, recording and reproduction with a high signal-to-noise ratio is possible, and since the servo track is provided on the protective layer side, tracking is possible. An optical recording medium that can be easily servoed can be obtained.

[Brief explanation of the drawing]

FIG. 1 shows a 4H optical recording medium showing an embodiment of the present invention.
Figure 2 shows the OIS substrate, 278 photosensitive film, 3.1. Reflective film, 4%
Thin protective layer, 51th hollow part, 6% thickest recording pit, 7th
%%%laser light. l[11Figure 8 No. 25a 231-

Claims (1)

[Claims] ``A photosensitive film is formed on a transparent first substrate, a reflective film is formed on a surface of a second substrate on which servo tracks are formed in a spiral or concentric form, and the photosensitive film surface of the first substrate and the second substrate are formed. A method for manufacturing an optical information recording medium, characterized in that the reflecting film surface of a substrate is tightly fixed.