JP2000251327A - Optical information recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a decrease in recording characteristics due to crosstalk between adjacent tracks and to secure the quantity of reflected light of the top level of the CD-R standards above a specific value by providing recessed parts on lands of a transparent substrate where grooves and the lands are formed alternately and concentrically or spirally and then suppressing the hollowing of a recording layer stack on the grooves. SOLUTION: When an original disk formed by coating glass with photoresist is irradiated with an exposure beam to cut a preformat pattern, the original disk is exposed continuously to a groove part and recessed parts formed between grooves by using two exposure beams and processes for development, plating, etc., are carried out to manufacture a stamper. A transparent substrate is manufactured by using this stamper. At this time, the recessed parts formed between the grooves are made continuous associatively with the groove part. On the transparent substrate, a recording film and a reflecting film are laminated. Thus, the recessed parts are formed between the grooves to make small the hollowing of the recording layer laminated on the grooves.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a write-once optical information recording medium using an organic dye as a recording film, and the shape of grooves and lands of the recording medium and spin coating, dipping, etc. on the grooves and lands. The present invention relates to a laminated state of a recording film made of an organic dye formed by using the coating method of (1).

[0002]

2. Description of the Related Art In recent years, an optical recording system for recording and reproducing information by irradiating an optical disk with a laser beam has been developed with the progress of laser technology for optical recording and a reduction in cost.

One of such optical information recording media is a write-once optical information recording medium containing an organic dye in a recording material.
There is DR. The recording layer of this optical information recording medium can be formed by dissolving a recording material containing an organic dye in a solvent and spin-coating, and compared to a magneto-optical recording medium in which the recording layer is formed by sputtering. It has the advantage of low manufacturing costs.

[0004]

A spiral groove portion is formed on a substrate of a write-once optical information recording medium such as a CD-R containing an organic dye as a recording material, and the spiral groove portion is formed. Land portions are arranged between the portions, and groove portions and land portions are alternately arranged in the radial direction.

When a recording layer is formed on this substrate by a spin coating method, as shown in the conventional example of FIG. 1, the recording layer becomes concave on the groove and convex on the land, so that a depression (dent) occurs.

On this recording layer, a reflective layer made of a metal film having a high reflectivity is formed to increase the contrast ratio, and a resin such as acrylic or epoxy is laminated as a protective layer.
CD-Rs, which are write-once optical information recording media containing an organic dye in a recording material, have been produced.

[0007] A pit (11T) and a pit (1T) are recorded on the CD-R, which is a write-once optical information recording medium manufactured as described above.
When a signal corresponding to the space portion (11T) between 1T) is written and reproduced, as shown in the conventional example of FIG.
In the reflected light amount at the above, the interference effect is reduced due to the occurrence of a depression in the recording layer laminated on the groove portion. For this reason, it may be 65% or less, which is the CD-R standard.

Further, when recording is performed on a portion of the recording layer laminated on the groove portion where a depression occurs, the recording portion tends to spread in the radial direction, and crosstalk occurs between adjacent tracks to reduce recording characteristics. There is a risk of lowering.

In the future, CD-Rs and the like, which are write-once optical information recording media containing organic dyes as recording materials, will need to be tact-up from the viewpoint of cost reduction. The depression of the recording layer laminated on the groove tends to become larger. Further, due to the higher density and higher performance, when the track pitch becomes narrower, the depression of the recording layer laminated on the groove portion becomes further larger.

[0010] An object of the present invention is to eliminate such disadvantages of the prior art and to suppress the depression of the recording layer laminated on the groove portion, thereby reducing the recording characteristics due to crosstalk between adjacent tracks. To the CD-R standard
An object of the present invention is to provide a write-once optical information recording medium containing an organic dye as a low-cost, high-density, and high-performance recording medium while ensuring a reflected light amount of 65% or more at a p level.

[0011]

According to the present invention, a recording layer is formed by applying a solution containing an organic dye on a transparent substrate having grooves and lands alternately formed concentrically or spirally on at least one surface. In the optical information recording medium in which a reflective layer is formed on the recording layer, a concave portion is provided on the land of the transparent substrate, so that the depression of the recording layer laminated on the groove portion is reduced. Then, by preventing the interference effect from being reduced, a reduction in the amount of reflected light is suppressed.

[0012]

FIG. 3 shows a method of exposing a master for producing a stamper for molding a substrate constituting a recording medium of the present invention. When irradiating a light beam onto the photoresist-coated master to cut a preformat pattern consisting of only grooves, the master is exposed to light beams for exposing the groove portions and the recesses formed between the grooves. Two beams are incident. Thus, the grooves and the concave portions between the grooves were exposed. The concave portions may be provided in a plurality of rows depending on design items such as a groove shape, a dye film thickness, and application conditions. In this case, two to three light beams,
It can be achieved by increasing the number one by one. After exposure of this master,
A stamper was prepared through processes such as development and plating.

Using this stamper, a transparent substrate made of polycarbonate resin was prepared by injection molding. As the resin, a known material other than polycarbonate can be used.

The preformat pattern of the stamper is transferred onto the transparent substrate prepared as described above. Of the transferred preformat patterns, the concave portions provided on the lands are continuous as shown in FIG. And discrete.

An organic dye was spin-coated on the preformat pattern forming surface of the transparent substrate to form a recording film. As organic dyes, cyanine, phthalocyanine,
Known materials such as azo dyes can be used. Preferably, indole cyanine dyes having the following methine chains are preferred.

[0016]

Embedded image

(T) in the formula is a carbon chain for constituting a methine chain, which is composed of a C ₃ -C ₁₇ linear or multi-membered ring.

A and A 'may be the same or different and each represents an aromatic ring.

B and B 'may be the same or different and represent -O-, -S-, -Se-, -CH = CH-, or

[0020]

Embedded image

(R ″ represents a C ₁ -C ₄ alkyl group such as CH ₃ , C ₂ H ₅ , C ₃ H ₇ , C ₄ H ₉ ).

R and R ′ may be the same or different and represent a C ₁ -C ₂₂ alkyl group, which may be substituted by a sulfonyl group or a carboxyl group.

[0023] X ^{- _{is, PF 4 -, CF 3 SO}} 3 -, SCN - represents one or more anions selected from the group of.

M and n are each 0 or an integer of 1 to 3, and have a relationship of m + n ≦ 3.

For the purpose of improving corrosion resistance, a quencher, an infrared absorbing material, and the like can be added.
As the additive, a known material such as aminium, imidium and the like can be used.

Further, a metal such as Au, Ag, Cu or the like or A
A metal containing u, Ag, Cu, etc. was formed by sputtering and a reflective film was laminated. A write-once optical information recording medium was formed by applying a protective film of an acrylic UV curable resin on the reflective film.

(Example 1) When a pre-format pattern is cut by irradiating a light beam to a master on which a photoresist is applied, a groove portion and a concave portion formed between the grooves are formed on the master by two light beams. Continuous exposure was performed using a beam, and after the exposure, a stamper was manufactured through processes such as development and plating.

Using this stamper, a transparent substrate made of a polycarbonate resin was produced by injection molding.

At this time, the recess formed between the grooves was continuous in conjunction with the groove. On this substrate, an indole cyanine dye having a methine chain shown below and an aminium salt were dissolved in a solvent, and a recording film was laminated to a thickness of 300 μm by spin coating. On this recording film, a 100 nm gold reflective film was laminated by sputtering.

Further, an acrylic UV-curable resin is applied so as to overcoat the recording film and the reflective film.
A protective film was formed by laminating μm, and an optical write-once optical information recording medium was manufactured.

Using a laser beam of wavelength λ = 780 nm for this medium and an optical lens of Na = 0.50,
A random pattern was recorded at a recording power of 7 mW and a linear velocity of 1.2 m / s. On the other hand, reproduction was performed using a laser beam having a wavelength of λ = 780 nm, using an optical lens with Na = 0.45, and a reproduction power of 0.1 mW and a linear velocity of 1.2 m / s. Table 1 shows the results of the reflected light amount and the crosstalk.

[0032]

[Table 1]

(Example 2) The same procedure as in Example 1 was carried out except that the light beam for the concave portion was exposed to light by repeating ON and OFF alternately.

(Comparative Example 1) When a preformat pattern is cut by irradiating a light beam to a master coated with a photoresist, only one groove portion is formed with respect to the master.
The procedure was the same as in Example 1 except that the light beam was used for exposure.

[0035]

By forming a concave portion between the land and the groove, the depression is suppressed, so that the amount of reflected light and the crosstalk between adjacent tracks can be reduced, and a low-cost, high-density, high-performance recording medium. As a result, it has become possible to provide a write-once optical information recording medium containing an organic dye.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a laminated structure according to a conventional example and an example of the present invention.

FIG. 2 is an explanatory diagram illustrating the amount of reflected light according to the related art and the present invention.

FIG. 3 is an explanatory view showing a master exposure step for producing a substrate of the present invention.

FIG. 4 is an explanatory view showing an embodiment of a concave portion provided between grooves of the present invention.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Takuhiro Yoshimizu 1-88 Ushitora, Ibaraki City, Osaka Prefecture Inside Hitachi Maxell Co., Ltd. (72) Inventor Takahiro Otsuka 1-188 Ushitora Ibaraki City, Osaka Prefecture F-term (reference) in Hitachi Maxell, Ltd. 5D029 WB01 WD11 WD16

Claims (3)

[Claims] 1. A recording layer is formed on at least one surface by applying a solution containing an organic dye on a transparent substrate in which grooves and lands are alternately formed concentrically or spirally. An optical information recording medium having a reflection layer formed thereon, wherein a concave portion is provided in a land portion of the transparent substrate. 2. The optical information recording medium according to claim 1, wherein the concave portions are provided continuously. 3. The optical information recording medium according to claim 1, wherein the concave portions are provided discretely.