JPH0451235A - Optical recording medium - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a computer memory and an optical recording medium for music and video. More specifically, it relates to write-once compact discs and write-once laser discs that are compatible with commercially available compact disc drives (players) and laser disc drives (players) and that can record once upon a time.

[Prior Art] Optical disks, optical cards, and optical tapes capable of large-capacity, high-density recording have been proposed as recording media for external memories for applications such as music, video, and computer memory. Among these, optical disks have been put into practical use for storing documents and medical records, and are becoming widespread.

In particular, compact discs, which are a form of optical disc, are widely used for music, and compact discs (CDs) that record map information and dictionaries for navigator systems are also popular.
-ROM has been devised and put into practical use.

The so-called laser disc, which is popular for compact discs and video, is functionally a playback-only type of optical disc. In other words, for boat fishing, after cutting and mastering the original recording, signals such as music and video are recorded in a mold called a stambar for precision injection molding of resin as minute irregularities on the surface. During injection molding of the substrate, fine irregularities corresponding to the signal are transferred from the stamper as irregularities on the surface of the substrate, and a reflective layer of aluminum, gold, or the like is applied. The light from the reading laser head is read as a change in reflectance due to the unevenness.

Therefore, these compact discs and laser discs, which are popular for video, are information media in which information is transmitted in one direction to the user, equivalent to publications and the like.

Here, there has been a desire for a recordable information medium that is compatible with compact discs and laser discs and that allows users to edit and write information, such as notebooks and cassette tapes. Addition here refers to writing information prepared by the user to part or all of the recording medium.

[Problems to be Solved by the Invention] The problem to be solved by the present invention is to make it compatible with drive systems that use optical recording media with reflective layers, such as drives for compact discs and laser discs, which are already in widespread use, while also being able to record additional data. The present invention provides an optical recording medium.

That is, more specifically, it has a reflective layer to maintain the same reflectance as conventional read-only media for compact discs and laser discs, but it also has photosensitivity that causes a sufficient change in reflectance when written with light. The present invention aims to provide an optical recording medium having the following characteristics.

As a result of intensive studies from this point of view, the present inventors have found that a donor layer and an acceptor layer, which produce a charge transfer complex which is an intermolecular compound when mixed, are separated by a separation layer, and a separation layer containing a light-absorbing dye is used. The present invention was completed by discovering that a new optical recording medium can be formed by irradiating the layer with light to melt it, mixing the donor layer and acceptor layer to develop color, and recording by modulating the light from the reflective layer.

[Disclosure of the Invention] That is, the present invention provides an optical recording medium having a recording layer on a transparent substrate and further having a reflective layer thereon, wherein the recording layer includes a donor layer containing a donor compound and an acceptor compound. The method comprises at least three layers: an acceptor layer and a separation layer that separates the donor layer and the acceptor layer, the separation layer contains a compound that absorbs recording light, and the charge is formed from the donor compound and the acceptor compound. The gist of the present invention is an optical recording medium characterized in that the mobile complex is capable of absorbing reproduction light.

The configuration and manufacturing method of the present invention will be described in detail below with reference to the drawings.

As described above, the structure of the present invention is characterized by having a recording layer between the transparent substrate and the reflective layer, and this recording layer includes a donor layer containing a donor compound, an acceptor layer containing an acceptor compound, and these donors. It includes at least three separation layers that separate the layer and the acceptor layer, the separation layer contains a compound that absorbs recording light, and a charge transfer complex formed from the donor compound and the acceptor compound absorbs the recording light. .

In the present invention, as shown in FIG.
A donor layer 2°O containing a donor compound is laminated on 0,
On top of that, the donor layer and acceptor layer are separated! 7
1300 is laminated, an acceptor layer 400 containing an acceptor compound is further laminated, and a reflective layer 50 is further laminated thereon.
The configuration with 0 is considered the minimum configuration. However, the donor layer and acceptor layer only need to sandwich a separation layer between them, and the donor layer and acceptor layer may have an interchanged configuration.
That is, an acceptor layer 400 containing an acceptor compound is first laminated on the substrate 100, a separation layer 300 for separating the donor layer and the acceptor layer is laminated thereon, a donor layer 200 containing a donor compound is further laminated, and the A configuration in which a reflective layer 500 is provided thereon may also be used.

In the present invention, a set of a donor layer, a separation layer, and an acceptor layer is used as a recording layer, and an undercoat layer may be provided between the substrate and this set, and a protective layer is provided between this set and a reflective layer. It does not matter if a layer is formed on the reflective layer.
There may be a preservation layer with a thickness of about 11 to 20 μm, or two layers may be laminated together with the uppermost reflective layers facing inside.

In the present invention, as shown in FIG. 2, one set of a donor layer, a separation layer, and an acceptor layer may have a plurality of sets each having a separation layer that absorbs different recording lights. There may be a coarse separation layer 600 that separates the groups.

The basic principle of recording in the present invention is shown in FIGS. 3 and 4 and will be explained below.

Before recording, a layer containing a donor compound and an acceptor compound forming a charge transfer complex that absorbs the recording reproduction light is separated by a separation layer containing a compound that absorbs the recording light. In this state, no charge transfer complex is formed, and the reproduction light is hardly absorbed and most of it is reflected by the reflective layer, resulting in a high reflectance. When the optical recording medium of the present invention is irradiated with recording light, the reflectance decreases in the following manner and a recorded signal can be obtained. That is, when the recording light is irradiated, the separation layer is heated and melted, and a portion of the donor layer and acceptor layer are thereby mixed and dissolved. As a result, a charge transfer complex that absorbs the reproduction light is formed in the film. This is schematically shown in FIG. 4. 300 is a separation layer that separates the donor layer and acceptor layer, and 700 is a region where the separation layer, donor layer, and acceptor layer are melted and mixed. The reflection of this region Writing occurs because the rate decreases.

The donor layer in the present invention contains 0.1% to 100% of a donor compound, and may also contain additives such as a binder resin and a surfactant.

The acceptor layer in the present invention contains an acceptor compound, and may also contain additives such as a binder resin and a surfactant.

The donor compound and acceptor compound in the present invention may be those that form an intermolecular charge transfer complex, and the generated charge transfer complex absorbs reproduction light. Regarding the obi, for example, you can use the entire Nippon Chemistry series ``New Experimental Chemistry Course 13'' as a mechanical structure (I).
I) Detailed explanation in Chapters J7 and 9.

The donor compound and acceptor compound in the present invention are also called an electron donor and an electron acceptor, respectively.

Examples of donor compounds include aromatic hydrocarbons, heteroaromatics such as pyridines and carbazoles, polyenes, aromatic anions, amines, ethers, thioethers, and anthraquinones.

On the other hand, examples of acceptor compounds include trinitrobenzene, p-benzoquinone and its derivatives, naphthoquinones, tetracyanoethylene, and other aromatic and unsaturated compounds containing multiple nitro groups, carbonyl groups, and cyano groups; Cations, halogen molecules such as iodine, hydrogen halides, halides such as carbon tetrachloride, BR3
, AlH3 (R is an alkyl group), Ag+ClO4-, and the like.

Regarding the absorption wavelength of charge transfer complexes produced by such combinations of donor and acceptor compounds, please refer to Nippon Chemistry Complete Edition "New Experimental Chemistry Course 13 Organic Structure (II)"
Examples are given in Chapter J7.9. Also, literature Ch.
Em, Lett, 905.1988 uses a charge transfer complex using carbazoles as a donor compound and naphthoquinones as an acceptor compound as an example, and shows that the maximum absorption wavelength can be estimated by the PPP method, which is a calculation method of the molecular orbital method. It is shown. Using these known data and estimation methods, donor and acceptor compounds that form a charge transfer complex that absorbs the reproduction light can be selected.

For example, a compound of formula (1) which is a donor compound having a carbazole ring, and a compound of formula (1) which is a naphthalenedione compound,
In the compound 2), a broad charge-transfer complex band with a maximum yield of 1 appears at 910 nm in a dichloromethane solution. In addition, when azulene is used as a donor compound and tetracyanoethylene is used as an acceptor compound, the wavelength is 740 nm in a chloroform solution, and when Frescene is used as a donor compound and tetracyanoethylene is used as an acceptor compound, the wavelength is 630 nm in a chloroform solution. −to,
When Brene was used as a donor compound and p-benzoquinone was used as an acceptor compound, 4
A broad band of charge transfer complexes appears with maximum absorption at 52n■.

The separation layer in the present invention is formed for the purpose of separating the donor layer and acceptor layer and preventing them from being mixed together and forming a charge transfer complex before recording. The separation layer contains a dye that absorbs recording light.The separation layer may also contain additives such as a resin binder, a surfactant, and a dye stabilizer.

The dye contained in the separation layer in the present invention is not particularly limited as long as it absorbs the writing light, but
Since semiconductor lasers are mainly used as the light source for playback and recording light for current compact discs and so-called laser discs, polymethine dyes such as cyanine and merocyanine, porphyrins, phthalocyanines, naphthalocyanines, etc. Preferred examples include azaannulene dyes, anthraquinone dyes, dithiol dyes, diamino metal complex dyes, xanthine and triphenylmethane dyes, and the like.

The donor layer, separation layer, and acceptor layer can be formed by a known method such as a vapor deposition method, a dipping method, a spin code method, a bar code method, and a roll coating method.

In general, in optical recording media, the yPL of the recording layer affects reflectance and recording sensitivity. The film thickness of the recording layer in the present invention varies depending on the donor compound, acceptor layer, and recording light absorbing dye used in the donor layer, acceptor layer, and separation layer, but the reflectance of the medium is )
It is preferably set to 65% or more in order to maintain compatibility with

Therefore, when the recording layer is laminated, it is preferable to set the film thickness so that the transmittance of reproduction light through the substrate is 70% or more.

Usually, it is desirable that the donor layer and acceptor layer each have a thickness in the range of about 25 nm to 200 nm.

Further, the thickness of the separation layer is desirably thinner than that of the donor layer and the acceptor layer, preferably from 5 nm to 150 nm.
It may be within the range of nm or less.

In the present invention, resin binders added to the donor layer, acceptor layer, and separation layer as necessary include acrylic resins such as polymethyl methacrylate and polymethyl acrylate; polyvinyl chloride; polyvinyl alcohol resins such as polyvinyl butyral; Vinyl resins such as vinyl acetate and vinyl chloride-vinyl acetate copolymers; polycarbonate resins; polyester resins; polystyrene resins; polyamide resins such as dimer acid polyamide; cellulose resins and copolymers and mixtures thereof; Preferred examples include organic carboxylic acids such as stearic acid and valmitic acid, and solid paraffin. These binders are preferably melted at a low temperature of 400°C or less in order to promote compatibility between the donor compound and the acceptor compound. is preferably 8
There is no particular limitation as long as it is 5% or more, but it is desirable that the optical anisotropy is small. Therefore,
For example, a glass substrate or a resin substrate can be used.

Examples of resin substrates include acrylic resin, polycarbonate resin, polyolefin resin, allyl resin, polyester resin, polyamide resin, which can be manufactured by injection molding.
Preferred are vinyl chloride resin, polyvinyl ester resin, and epoxy resin.

The shape of these substrates may be plate-like, film-like, circular or card-like, and the surface of the substrate may have base circular grooves representing recording positions or irregularities on which read-only information has already been recorded.

The reflective layer used in the present invention is not particularly limited as long as it has a reflectance of preferably 80% or more for the light actually read out.The reflectance here is measured using an aluminum mirror surface as a control sample. 5 degree specular reflectance. Preferred materials include aluminum and gold because of their ease of manufacture, economy, and durability.

The method for forming the reflective layer in the present invention is preferably 10n
The reflective layer may be laminated on the recording layer with a thickness of about 200 nm, and is not particularly limited. For example,
Preferred examples include vacuum evaporation and sputtering.

In the optical recording medium of the present invention, a semiconductor laser having an oscillation wavelength in the range of 640 nm to 850 nm is generally preferred as the light source for signal readout light, and is compatible with commercially available compact disc drives (players) and laser disc drives (players). 7 considering the compatibility of
The light source for the signal recording light, which is particularly preferably 80 nm, is not particularly limited, but it is preferably in the semiconductor laser oscillation wavelength range, and more preferably the same as the light source for the readout light. For example, when recording at a linear velocity of 1.2 m/s to 1.4 m/s, the laser output on the recording film is set to about 5 mW to 10 mW, and when reading out, the laser output is set to about 10 mW at the time of recording. It should be about 1.

[Operations and Effects] The optical recording medium of the present invention can have very good recording characteristics while having a high reflectance with a reflective layer compatible with compact discs and laser discs.

[Examples] Hereinafter, the present invention will be specifically explained using Examples, but it must be understood that these are merely illustrative and do not limit the technical scope of the present invention.

Example 1 Spiral guide groove with a thickness of 1.2 mm and a diameter of 120 mm (depth 70 nm, width 600 nm, pitch 1600 nm)
The following formula (1) is applied to the inner periphery of the polycarbonate substrate with
1 wt% of donor compound and polyvinyl butyral resin (
A 2 wt % methyl cellosolve solution (trade name: Kosuretsu BM-2 manufactured by Sekisui) was added dropwise, and the substrate was rotated at a rotational speed of 11,000 rp to coat it in a thickness of 80 nm using a spin code method. Immediately after coating, it was dried for 30 minutes at 40°C under dry nitrogen to form a donor layer.

On this separation layer, an acceptor compound of the following formula (3) was vacuum-deposited under a reduced pressure of 1.3xlO-5torr, and 6
A layer of 0 nm was laminated as an acceptor layer. This 31
A gold reflective film with a thickness of 60 nm was formed on the recording layer of the structure by vacuum evaporation.

Furthermore, an ultraviolet curable protective coating film of 10 μF was applied and cured on the gold reflective layer to produce an optical recording medium.

8HI7 Next, a 0.4 wt% octane solution of the following formula (2) was rotated at a rotation speed of +200 rpm, and similarly
5nml cloth and drying was performed.

llH17 (2) Place this optical recording medium on a turntable of 1.4 m.
While rotating at a linear velocity of /S, a drive (player) with an optical head equipped with a semiconductor laser with an oscillation wavelength of 780 nm was used to control the laser beam to be focused on the recording layer on the guide groove through the resin substrate. When the reflectance was measured, a reflectance of 75% was observed.

Next, an IMHz pulse signal (pulse width 500 ns) was recorded on the recording surface with a laser output of 10 mW. After this, the output of the semiconductor laser was lowered to 1 mW on the recording surface.
The recorded signal was read out. The quality of the read signal is evaluated by the signal-to-noise ratio (C/N), and this value is 5.
A sufficiently high value of 2 dB was obtained, and good recording and reproduction was performed.

Example 2 A spiral guide groove with a thickness of 1.2 mm and a diameter of 120 mm (depth of 7 Q nm, radius of 600 nm, pitch of 1600 nm)
) on the inner periphery of the polycarbonate substrate with machining allowance (1)
1 wt% of donor compound and polymethyl methacrylate resin (trade name: Acryvet MF manufactured by Mitsubishi Rayon) 2
Add wt% methyl cellosolve solution dropwise and rotate at a rotation speed of 11
3Q by rotating the substrate at 000 rpm and using the spin code method.
nm was applied. Immediately after coating, it was dried for 30 minutes at 40°C under dry nitrogen to form a donor layer.

Next, the 0.4 wt % octane solution of the previous generation (2) was rotated at a rotation speed of 1200 rpm, and a 15 nm spin cord was applied and dried in the same manner to form a separation layer.

Furthermore, tetracyanoethylene as an acceptor compound was vacuum evaporated under a reduced pressure of 1.0xlO-5 torr, and 5
A layer of 0 nm was laminated as an acceptor layer.

, a thickness of 6 mm was deposited on the recording layer of the three-layer structure by vacuum evaporation method.
A 3 nm gold reflective film was formed, and an ultraviolet curable protective coating film of 10 μm was coated and cured on the gold reflective layer to produce an optical recording medium.

(2) Place this optical recording medium on a turntable 14 m
While rotating at a linear velocity of /s, a drive (player) with an optical head equipped with a semiconductor laser with an oscillation wavelength of 780 nm was used to control the laser beam to be focused on the recording layer on the guide groove through the resin substrate. When the reflectance was measured, a reflectance of 71% was observed.

Next, an IMHz pulse signal (pulse width 500 ns) was recorded on the recording surface with a laser output of 10 mW. After this, the output of the semiconductor laser was lowered to 1 mW on the recording surface.
The recorded signal was read out. This C/N value is 50dB
A sufficiently high value was obtained, and good recording and reproduction was performed.

Example 3 Spiral guide groove with a thickness of 1.2 mm and a diameter of 120 mm (depth 70 nm, radius 600 nm, pitch 1600 nm)
Tetraquinodimetha 7 (TCNQ) was added at 1.0% as an acceptor compound on the inner periphery of a polycarbonate substrate having
An 80 nm acceptor layer of XIO-5 torr was deposited.

Next, polyvinyl butyral resin (product name Kosuretsuku BM)
-2 manufactured by Sekisui) 2wt% and cyanine dye NK114
A 0.2 wt % methyl cellosolve solution of No. 4 (manufactured by Nippon Kanko Shokuryo) was added dropwise, and the substrate was rotated at a rotation speed of 2200 rpm to coat it in a thickness of 60 nm using a spin code method. Immediately after coating, it was dried for 30 minutes at 40°C under dry nitrogen to give a solution of NN.

Next, add azulene as a donor compound to 1.1χIQ-5t
An acceptor compound of the following formula (3) was vacuum-deposited under a reduced pressure of 50 nm to form an acceptor layer.

A thickness of 60 mm was deposited on this 3N structure recording layer by vacuum evaporation.
A gold reflective film of nm thickness was formed, and then an ultraviolet curable protective coating film was applied on the gold reflective layer using a 10μI12 cloth and cured to produce an optical recording medium.

(2) Place this optical recording medium on a turntable 14 m
While rotating at a linear velocity of /s, a drive (player) with an optical head equipped with a semiconductor laser with an oscillation wavelength of 7BOnm was used to control the laser beam to pass through the resin substrate and focus on the recording layer on the guide groove. When the reflectance was measured, a reflectance of 76% was observed.

Next, a 1 MHz pulse signal (pulse width 500 ns) was recorded on the recording surface with a laser output of 10 mW. After this, the output of the semiconductor laser was lowered to 1 mW on the recording surface.
The recorded signal was read out. This C/N [is 55 dB
A sufficiently high value was obtained, and good recording and reproduction was performed.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of the layer structure of the optical recording medium of the present invention. FIG. 2 shows another embodiment of the optical recording medium of the present invention, and is a schematic diagram in which the optical recording medium has a plurality of donor layers, HN layers, and acceptor layers. 3 and 4 are diagrams for explaining the present invention in detail,
FIG. 3 shows the state before recording, and FIG. 4 shows the state after recording as schematic V. In the figure, 100--transparent substrate, 200--donor layer, 300--one separation layer, 400--acceptor layer, 500--one reflective layer, 600-- - Rough separation layer that separates the set of donor layer, separation layer, and acceptor layer, 700------A region where the donor layer, acceptor layer, and separation layer are melted and mixed.

Claims (1)

[Claims] (1) In an optical recording medium that has a recording layer on a transparent substrate and further has a reflective layer thereon, the recording layer includes a donor layer containing a donor compound, an acceptor layer containing an acceptor compound, and these donor layers. and an acceptor layer, the separation layer contains a compound that absorbs recording light, and the charge transfer complex formed from the donor compound and the acceptor compound absorbs reproduction light. An optical recording medium characterized by being transparent.