JPH058116B2 - - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical card, and particularly to an optical card that performs heat mode optical recording. Prior Art and its Problems Generally, magnetic recording methods are widely known for recording and reproducing information. For example, magnetic tape,
Examples include magnetic recording media such as magnetic disks and magnetic cards. One example of this use is a magnetic card used as a cash card or the like.
As is well known, magnetic recording and reproducing methods are used to record information,
Erasing and re-recording can be easily performed. Therefore, if a magnetic card using this method is misused or placed in a magnetic field caused by a magnet, the information recorded on the card may change, resulting in low information reliability. Further, magnetic cards have the disadvantage that they can only record information at a low density due to limitations of the magnetic head, and furthermore, they can only record a very small amount of information due to limitations based on the size of the card. Therefore, it is impossible to take a complicated signal form to prevent misuse due to the above-mentioned limitations on magnetic cards. Recording and reproducing methods based on optical principles have recently been proposed to improve these drawbacks. Examples of devices based on this optical recording and reproducing method include optical disks and optical cards. Among these, optical cards have a wide range of applications, including bank cash cards, credit cards,
It is expected that it will be put to practical use in a wide variety of applications, including identification cards, driver's licenses, commuter passes, public telephone cards, and gasoline purchase cards. By the way, there is a heat mode optical recording medium that can be applied to an optical card. This heat mode optical recording medium is an optical recording medium that uses recording light as heat. One example is a heat mode optical recording medium that uses recording light such as a laser to melt or remove a part of the medium, which is called a pit. There is a pit-forming type in which writing is performed by forming small holes, information is recorded using the pits, and reading is performed by detecting the pits with a readout light. Most of these pit-forming type media, especially those using a semiconductor laser as a light source that can make the device smaller, have a recording layer made of a material mainly composed of Te. However, in recent years, it has become clear that Te-based materials are harmful.
In addition, due to the need for higher sensitivity and lower manufacturing costs, Te
Instead, there are an increasing number of proposals and reports on media using recording layers made of organic materials containing various dyes. However, with the above pit-forming type media,
When used as an optical card, when the recording layer is tightly sealed with a protective film, the contrast and sensitivity are reduced. Therefore, it is still insufficient in terms of contrast, sensitivity, etc., and future improvements are desired. OBJECTS OF THE INVENTION It is an object of the present invention to provide an optical card having high contrast and sensitivity, and having a structure in which the recording layer changes reflectance in a state in which substantially no unevenness is formed (pittleless) when irradiated with recording light. be. DISCLOSURE OF THE INVENTION These objects are achieved by the invention described below. That is, the present invention comprises: a substrate; an optical recording section having a recording layer and a reflective layer having a light absorption layer and a changeable layer, or a recording layer and a reflection layer in which the light absorption layer and the light absorption layer are mixed and integrated; and a protective film; The layer contains a light-absorbing dye, the variable layer contains a polymeric liquid crystal containing a dichroic dye or a thermosensitive dye, and when irradiated with recording light, the transmittance of the recording layer is changed in a state where substantially no unevenness is formed. This optical card is characterized in that a change in reflectance occurs from the reflective layer, and playback is performed by detecting the change in reflectance. Specific Configuration of the Invention The specific configuration of the present invention will be described in detail below. FIG. 1 shows an embodiment of the invention. As shown in FIG. 1, an optical card 1 of the present invention
has a substrate 2. The substrate 2 is usually made of a resin material, and may be made of acrylic resin, polycarbonate, nylon, polyolefin, or the like. However, in consideration of printability, lamination properties, moisture resistance, strength, etc., polyvinyl chloride-based polymers are preferred. The polyvinyl chloride-based polymer may be a vinyl chloride homopolymer or a vinyl chloride copolymer such as vinyl chloride-vinyl acetate or vinyl chloride-maleic acid. The thickness of the substrate 2 is approximately 0.1 to 1.0 mm. A reflective layer 3 is provided on the substrate 2 . The material of the reflective layer 3 is usually Al, Au,
Metals such as Cr, Ag, and Ni are preferred. The thickness of the reflective layer 3 is approximately 50 to 300 Å. Note that the reflective layer 3 may be provided as an upper layer of the recording layer 4. On the reflective layer 3, there is provided an optical recording section for recording in a so-called pitless manner, which is configured to change the transmittance by irradiation with recording light without forming substantially any unevenness. The recording section usually has a changeable layer 4 made of polymeric liquid crystal containing a thermosensitive dye or preferably a dichroic dye. First, the case where a thermosensitive dye is used in the changeable layer 4 will be described. Here, the heat-sensitive dye refers to a colorless dye that is usually a colorless or slightly colored powder, but has the property of developing color by reacting with a color developer. Below, colorless dyes are classified by compound structure, and specific compounds and literature describing them are shown. () Phthalide type () Fluoran type a Crystal violet lactone (CVL) Described in U.S. Patent No. 2717897 b Pyridine Blue Described in Japanese Patent Publication No. 16807-1987 Described in Japanese Patent Application Laid-open No. 212092-1987 c 3-Cyclohexylamino- Described in 6-Chlorofluoran Special Publication No. 1983-29550 d Described in 3-Diethylamino-6-methyl-7-chlorofluoran Special Publication No. 1982-21199 e 3-Diethylamino-7-dibenzylaminofluoran Special Publication No. 1983 -Described in No. 4614 f 3-diethylamino-6-methyl-7-anilinofluoran Described in Japanese Patent Publication No. 1983-43296 g Other Japanese Patent Publications No. 51-15445 No. 51-23204 No. 58-209589 Publication No. 51-121035 No. 157779 No. 55-32559 No. 7453 No. 7453 No. 7453 No. 65754 No. 29663 No. 47 Described in British Patent No. 1339316 etc. () Phenothiazine Types () Phenoxazine type () Auramine type () Rhodamine lactam type () Spiropyran type () Triphenylmethane type () Others a Benzoyl leucomethylene blue (BLMB) Described in Japanese Patent Publication No. 8557 of 1972 b Carbazoyl Blue Special Publication of 1977 12515 c Dihydroquinazoline Blue described in JP-A-58-192885 d Chromenoazaindolizine Blue described in JP-A-58-192887, etc. The color developer includes bisphenol A (BPA), 2,
Organic color developers of phenol compounds, which are organic acids such as 2-bis(4-hydroxyphenyl)n-heptane and 1,1-bis(4-hydroxyphenyl)cyclohexane, and activated clay. There are some inorganic color developers, but any of them may be used. The colorless dye and the color developer may be used either in the form of microcapsules using a binder, or by using a binder soluble in water or water-alcohol. Any binder may be used for the microcapsules, and examples of binders soluble in water or water-alcohol include polyvinyl alcohol (PVA),
Examples include cellulose derivatives such as methylcellulose, ethylcellulose, and hydroxyethylcellulose, and partial hydrolysates of vinyl acetate-ethylene copolymers. When a polymer liquid crystal containing a dichroic dye is preferably used in the changeable layer 4, the polymer liquid crystal has a liquid crystal group in the main chain or side chain, and has an average molecular weight of 500 or more. be. Further, the polymer liquid crystal may be crosslinked. Furthermore, it is even more preferable that the crosslinking be photocrosslinking. Specific examples of polymer liquid crystals used are listed below.
Note that in the following, * indicates an asymmetric carbon system.

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[Table] As the dichroic dye contained in the polymer liquid crystal, the following are preferable. (A) Merocyanine pigments (B) Anthraquino pigments (C) Azo pigments (D) Styryl pigments (E) Azomethine pigments (F) Tetrazine pigments (G) Methine pigments (H) Squarylium pigments, etc. The polymer liquid crystal used is one that has been oriented in advance by applying an electric field, or one that contains an alignment agent. The following alignment agents are suitable for use. (1) Solution application (physical adsorption) (a) Vertical orientation Lecithin, stearic acid, CTAB (hexadecyltrimethylammonium bromide),
Octadecylamine hydrochloride etc. (b) Parallel orientation Carbon, polyexyethylene, Versamide 125, polyvinyl alcohol, polyimide, etc. (2) Solution coating (chemical adsorption) (a) Vertical alignment Monobasic carboxylic acid chromium complex (e.g. chromium myristate complex, perfluorononanoate chromium complex), organic silane (e.g.
DMOAP) etc. (b) Parallel orientation dibasic carboxylic acid chromium complex (e.g. chromium brassylate complex), organic silane (e.g.
MAP) etc. (3) Plasma polymerization (a) Vertical alignment Hexamethyldisiloxane, perfluorodimethylcyclohexane, tetrafluoroethylene, etc. (b) Parallel orientation acetylene, etc. (4) Sputtering (a) Vertical alignment polytetrafluoroethylene, etc. (5) Liquid crystal dissolution injection (physical adsorption) (a) Vertical alignment lecithin, CTAB, Versamide 100, octadecyl malonic acid, etc. (b) Parallel oriented dibasic fatty acids (e.g. HOOC (CH ₂ )
nCOOH, n=3-11), Versamide 125, Crown Ether, etc. In addition to the polymeric liquid crystal and the dichroic dye, the recording layer may contain a low-molecular liquid crystal, various stabilizers, quenchers, and the like. When using a thermosensitive dye, the thickness of the changeable layer 4 is as follows:
If a polymer liquid crystal containing a dichroic dye is used, the thickness may be 0.5 to 30 μm. The changeable layer 4 is provided with a light absorption layer 5 containing a light absorption dye. However, the light-absorbing layer 5 does not need to be clearly provided as a layer, and a light-absorbing dye may be mixed in a varying amount and used as a recording layer. Furthermore, either the light absorption layer 5 or the variable layer 4 may be located on the upper layer. The light-absorbing dye to be used may be appropriately determined from among those that effectively absorb the wavelengths of the writing light and reading light. In this case, it is preferable to use a semiconductor laser as the light source from the standpoint of miniaturizing the device, so the dyes may be cyanine-based, phthalocyanine-based, anthraquinone-based, azo-based, triphenylmethane-based,
Preferred are pyrylium or thiapyrylium salt-based complex groups, bisphenyldithiol-based complex groups, and the like. Further, when the dye composition is used as a light absorption layer, a self-oxidizing resin such as nitrocellulose, or a thermoplastic resin such as polystyrene or nylon can be contained. Furthermore, a quencher may be included in order to prevent oxidative deterioration of the dye. Furthermore, other additives may also be included. In such cases, particularly preferred are mixtures of indolenine-based cyanine dyes and quenchers such as bisphenyldithiol-based quenchers, and phthalocyanines. It is also preferable to use these as an ionic bond between a dye cation and a quencher anion. In such a case, the light absorption layer may be formed by coating using a ketone, ester, ether, aromatic, halogenated alkyl, or alcohol solvent. Furthermore, the light absorption layer may be a metal layer provided by vapor deposition or the like. Al as the metal layer,
There are single metals or alloys such as Au, Ag, Ni, Cr, In, and Sn. Further, the light absorption layer may be a laminate of a metal layer and a dye layer. Such a light absorption layer may have a thickness of 0.01 to 10 μm, and preferably has a thickness of 0.05 to 0.1 μm. In addition, when the change layer contains a light-absorbing dye,
For heat-sensitive dyes, the weight ratio is 0.1 to 1 light-absorbing dye.
~100, and in a polymer liquid crystal containing a dichroic dye, the weight ratio is 0.01 to 10 with respect to 1 part of the polymer liquid crystal. A protective film 6 is provided on the optical recording section having the variable layer 4 and the light absorption layer 5. Although the protective film 4 can be formed by coating, it is usually formed by fusing or adhering a film body. Various resins are suitable as the material for the protective film 4, but the above-mentioned polyvinyl chloride polymer is particularly suitable in terms of moisture absorption and scratch resistance. The thickness thereof is approximately 0.05 to 1.0 mm. This is because if it is less than 0.05 mm, recording and playback will be hindered by the influence of dust and dirt, and if it exceeds 1.0 mm, it will be unsuitable for practical use. In addition, the protective film 4 may have various coating layers for preventing scratches. Further, the substrate may have an optical recording section and a protective layer on both sides thereof, or these may be provided only on one side. In the latter case, a protective film may be formed on the back surface of the substrate. Specific Effects of the Invention According to the present invention, the optical recording section is configured to change its transmittance without substantially forming unevenness by irradiation with the recording light, and this is detected by the change in reflectance due to the reflection phase. Therefore, an optical card with high contrast and sensitivity can be obtained. Furthermore, it has excellent raw preservation properties and archival preservation properties. Specific Examples of the Invention Hereinafter, specific examples of the present invention will be shown, and the effects of the present invention will be explained in further detail. Example 1 On a vinyl chloride resin sheet of 85 x 50 x 0.3 mm
A reflective layer of Al with a thickness of 200 Å was provided, and a light absorbing layer with a thickness of 0.1 μm was formed on this using a bisphenyldithiol Ni complex (PA1006 manufactured by Mitsui Toatsu Chemical Co., Ltd.) as a light absorbing dye. . Furthermore, CVL is added as a colorless dye on top of this light absorption layer, and CVL is added as a color developer.
A recording layer was formed to a thickness of 0.5 μm using BPA and PVA as a binder. At this time, PVA
The weight ratio of CVL and BPV was 1:10. next,
A 0.1 μm thick sheet made of vinyl chloride resin was heat-sealed thereon as a protective film. The optical card produced in this way has a wavelength of 830n.
When recording was performed at a wavelength of 830 nm and an output of 1 mW, the contrast was 2.3. Example 2 An optical card was prepared in the same manner as in Example 1 except that the recording layer and the light absorption layer were reversed, and when recording and reading were performed in the same manner as in Example 1, the contrast was It was 2.1. Example 3 An optical card was produced in the same manner as in Example 1, except that a polymer liquid crystal and a dichroic dye were used in the recording layer instead of the heat-sensitive dye (a combination of a colorless dye and a color developer). . In this case, the polymer liquid crystal has
Anthraquinone dyes were used as Lc1 and dichroic dyes. Recording and reading were performed in the same manner as in Example 1, and the contrast was 2.2. From the above, the effects of the present invention are clear.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the optical card of the present invention. Explanation of symbols, 1... Optical card, 2... Board, 3
... Reflection layer, 4 ... Changeable layer, 5 ... Light absorption layer, 6
……Protective film.

Claims (1)

[Claims] 1. Has a substrate, a light absorption layer and a changeable layer, or
an optical recording section having a recording layer and a reflective layer which are mixed and integrated with a light absorption layer, and a protective film, the light absorption layer containing a light absorption dye, and the changeable layer containing a dichroic dye. When irradiated with recording light, the recording layer changes its transmittance without forming substantial irregularities, causing a change in reflectance from the reflective layer, and detecting the change in reflectance. An optical card that is characterized by being played back.