JPH0546987A - Formation of recording section of draw type optical disk - Google Patents

Abstract

PURPOSE:To realize stable and sure recording by decomposing pigments in a light absorbing layer from each other by irradiating the layer with light, diffusing one part of the pigments into a substrate, allowing the other part to recohere, and forming a recording section by changing the optical constant of the irradiated section. CONSTITUTION:When a light absorbing layer formed on a substrate 11 by application is irradiated with recording light, the layer 12 absorbs the recording light and converts the light into thermal energy. Pigments contained in the layer 12 as recording compositions are decomposed from each other and part of the decomposed pigments are diffused into the substrate 11, especially, along the inner peripheral side of a group 70 and form a diffusion layer 51. The other part of the decomposed pigments, on the other hand, are recohered in the group 70 and form a separated pigments recohesion section 55. Since the formation of the section 55 and layer 51 changes the optical constant of the sections irradiated with the recording light, a recording section can be formed. When such recording section forming method is used, recording can be made extremely stably and surely. It is preferable to use a cyanine pigment as the pigments contained in the layer 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a write-once write-once type optical disc which is rewritable by a so-called general CD player.

[0002]

2. Description of the Related Art In recent years, a write-once write-once type optical disc, which is a writable write-once type optical disc and can be directly reproduced by a general CD player, has been actively developed and proposed to meet the needs of the market. In particular, regarding the recording principle or method of such an optical disc, the principle that "the dye is decomposed and heat is generated, the substrate material is deformed and swelled, and just the phase pit is formed" is made public.

[0003]

However, the length of the bulge called the phase pit (the length in the time axis direction) is not constant for recording at the same frequency and is 2 with respect to the center value.
It has been experimentally confirmed that a variation of about 0% is exhibited, and in general, the above principle causes a large jitter and a so-called beautiful eye pattern reproduction waveform cannot be obtained. Therefore, the recordings that will be made according to the above principle can be said to be extremely unstable. In fact, it has been experimentally confirmed that the height of the bulge of the substrate increases as the depth of the groove increases, and originally, for example, two media having different groove depths have different modulation degrees. Should be. However, they have the same degree of modulation, and it can be said that this result does not support the proposed principle at all.

The present invention was devised under such circumstances, and an object thereof is to propose a method of forming a recording portion of a write-once optical disc capable of extremely stable and reliable recording.

[0005]

In order to solve such problems, the present invention provides a light-transmissive substrate, a light-absorbing layer containing a dye provided on the substrate, and a light-absorbing layer of the light-absorbing layer. A recording method of a write-once optical disc having a light reflection layer provided on the optical recording medium, wherein the method decomposes the dye contained in the light absorption layer by light irradiation, and a part of the decomposed product inside the substrate. It was carried out by changing the optical constant of the irradiated portion by causing the other decomposed substances to re-aggregate and diffused.

[0006]

[Function] By irradiating light, the dye contained in the light absorption layer is decomposed, a part of the decomposed product is diffused inside the substrate, and a part of the other decomposed product is re-aggregated to change the optical constant of the irradiated part. The recording portion is formed by changing the recording portion.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic sectional view for explaining the structure of a write-once optical disc which is a recording object of the present invention. For simplification, FIG. 1 shows only the left side from the center of rotation of the disk in cross section.

In the write-once optical disc 1 of the present invention, a light absorbing layer 12 is provided on a disc-shaped light transmitting substrate 11, and a light reflecting layer 13 is provided on the light absorbing layer 12.
A protective layer 14 is formed on the light reflection layer 13.

As shown in FIG. 1, a tracking pre-groove 70 is provided on a flat surface on one side of the light-transmissive substrate 11.
It is formed concentrically or spirally. As the substrate 11 having such a pre-groove 70, it is preferable to use a so-called integrally formed injection-molded resin substrate from the viewpoint of improving productivity.
It is formed of a transparent material such as polycarbonate resin (PC) or polymethylmethacrylate resin (PMMA). Further, the substrate is not limited to the injection-molded resin substrate integrally formed, and may be a substrate formed by a so-called 2P (photo-polymer) method. The thickness of the substrate 11 is 1.0 to 1.5.
It is about mm.

The light absorption layer 1 is formed on the substrate 11.
2 is formed into a film, and the light absorbing layer 12 contains a cyanine dye as a recording composition. As the cyanine dye, for example, those represented by the following general formula [I] are suitable.

[0011]

[Chemical 1] In the above general formula [I], R ₁ and R ₂ each represent an alkyl group having 1 to 8 carbon atoms, preferably an alkyl group having 1 to 4 carbon atoms. X ⁻ represents a counter ion, and specific examples thereof include ClO ₄ ⁻ , I ⁻ , Br ^{− and the} like. n represents an integer of 2 or 3, preferably 2.

More specifically, the following structural formulas [II] to
Examples include cyanine dyes represented by [III].

[0013]

[Chemical 2]

[0014]

[Chemical 3] Such a cyanine dye works particularly effectively in realizing the method for forming the recording portion of the present invention described later.

The light absorbing layer 12 containing such a cyanine dye is coated by a conventional means such as spin coating. The applied light absorption layer 12 is formed so as to leave the inner peripheral edge portion and the outer peripheral edge portion on the substrate 11 as shown in FIG. The thickness of the applied light absorption layer 12 is about 20 to 2000 nm. As the solvent used for coating, various known solvents are used, and examples thereof include diacetone alcohol, ethyl cellosolve, methyl cellosolve, isophorone, methanol, tetrafluoropropanol and the like.

Further, from the viewpoint of preventing photo-deterioration of the cyanine dye in the light absorbing layer 12, it is preferable to include a quencher on the light absorbing layer 12 as described above. Is provided. Light reflection layer 13 is A
It is made of a metal such as u, Ag, Cu or Al, and is formed by vacuum vapor deposition, sputtering, ion plating or the like. The thickness of the light reflection layer 13 is 0.02 to 2.
It is set to about 0 μm.

Further, a protective layer 14 is usually provided on the light reflection layer 13 to protect the light absorption layer 12 and the light reflection layer 13. The protective layer 14 is generally formed by spin-coating an ultraviolet curable resin and applying it, and then irradiating it with ultraviolet rays to cure the coating film. Besides, an epoxy resin, an acrylic resin, a silicone resin, a urethane resin or the like is used as the protective layer 14.
Used as a material for. The thickness of such a protective layer 14 is usually about 0.1 to 100 μm. An intermediate layer for protecting the substrate 11 from a solvent may be provided between the substrate 11 and the light absorption layer 12. Light absorbing layer 12
An intermediate layer for improving the efficiency of light absorption may be provided between and the light reflection layer 13.

A method of forming the recording portion of such a write-once optical disc will be described in detail below with reference to FIG. First, recording light (semiconductor laser beam) is irradiated from the substrate side so as to be condensed on the light absorption layer 12 coated on the substrate 11. Then, the light absorption layer 12 efficiently absorbs this recording light (semiconductor laser beam) and converts it into heat energy. As a result, the pigment is decomposed. Then,
As shown in FIG. 2B, a part of the decomposed product diffuses inside the substrate, particularly along the inner periphery of the groove 70, at substantially the same diffusion rate, and a diffusion layer is formed on the inner periphery of the groove of the substrate. 51 is formed. On the other hand, other decomposed products that have not contributed to the diffusion re-aggregate in the groove to form the decomposed product aggregating portion 55. By forming the decomposed product aggregating portion 55 and the diffusion layer 51, the recording portion is formed by changing the optical constant of the recording light irradiation portion.

The following method was used to confirm that the recording is actually performed by the method for forming the recording portion. That is, the physical properties such as the refractive index, the absorption coefficient, and the thickness in the diffusion layer 51 and the decomposition product agglomeration part 55 are estimated, and the ratio of the diffusion layer 51 and the decomposition product agglomeration part 55 is calculated using these physical property values. When the reproduced waveform is simulated and drawn with various composition ratios, R actually output at a certain composition ratio
It was confirmed that a waveform substantially the same as the f reproduced waveform was obtained by calculation.

[0020]

According to the method for forming a recording portion of the present invention, the dye contained in the light absorbing layer is decomposed by irradiation with light, and a part of the decomposed product is diffused into the substrate, while other decomposed products are formed. Since the recording is performed based on the principle of re-aggregating a part and changing the optical constant of the irradiated portion, extremely stable and reliable recording can be performed as compared with the conventionally proposed recording by the substrate deformation method.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view for explaining a structure of a write-once optical disc which is a target of a method of forming a recording portion of the present invention.

FIG. 2 is a cross-sectional view for schematically and temporally explaining the method of forming a recording portion of the present invention.

[Explanation of symbols]

 11 ... Substrate 12 ... Light absorption layer 13 ... Light reflection layer 14 ... Protective layer

Claims (2)

[Claims] 1. A recording portion of a write-once optical disc having a light transmissive substrate, a light absorbing layer containing a dye provided on the substrate, and a light reflecting layer provided on the light absorbing layer. In the method, a dye contained in the light absorption layer is decomposed by light irradiation, a part of the decomposed product is diffused into the substrate, and a part of other decomposed product is re-generated. A method of forming a recording portion of a write-once type optical disc, which comprises forming the recording portion by causing aggregation and changing an optical constant of an irradiated portion. 2. The method for forming a recording portion of a write-once optical disc according to claim 1, wherein the dye is a cyanine dye and the dye is decomposed.