JPH07107756B2 - Light card - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an optical card capable of optical additional writing.

[Prior art and its problems]

In recent years, a large number of magnetic cards have been issued and used as cash cards, credit cards, etc. due to their safety, reliability, convenience, and user portability in commercial transactions of financial institutions such as banks and credit sales. . Further, as another application field of the magnetic card, it is also widely used as a personal identification certificate in companies and schools for the above reasons. Although it is a magnetic card that has already penetrated deeply into social life in this way, as the field of application expands, it will become necessary for the card issuing side and the user side to add higher functionality to the card. It's coming. The main requirement is due to the small amount of information that can be stored in current magnetic card media. Of course, the lack of the amount of stored information here is not only in the sense of not only the essential information originally required, but also of the redundant information that functions to protect the essential information.

From such a background, IC cards and optical cards have been proposed as card media having a larger storage capacity. In particular, the latter is considered to be the most effective as a storage medium for personal information because it has a huge storage capacity.

Currently proposed optical cards are a read-only optical card and an additional writable card, but the former is fixed information that cannot write new information. Cannot meet all the needs of various users.

By the way, a wide range of recording principles and recording materials have already been proposed as direct read after write (DRAW) as an optical information recording method. That is, rather than using the radiation from a light source such as a laser as an excitation light source in the photon mode of silver salts and diazonium salts, which have been known for a long time, the transition, expansion, melting, and decomposition due to the temperature dependence of the physical properties of materials. This is so-called heat mode recording, which is used as a heat source for causing physical and chemical changes such as. Therefore, in this heat mode recording, as long as the photosensitive material is not exposed to radiant light before and after desired recording, the photosensitive material is not heated to a temperature that causes a physical change that causes permanent deformation. It has the characteristic that it is not affected by this. This has the advantage that it is not necessary to handle the recording medium in a limited environment such as a dark room. Another feature of the conventionally proposed system is that the recording portion, that is, the pit portion is achieved by the removal of the photosensitive material. This means that the recording format on the medium side is digitally expressed as an analogy to the digital signal in the input / output device to / from the recording medium. By the way, all of the recording systems that have been studied so far are based on the shape of a disk, so there is a problem in functioning as an optical card that can be additionally written by porting these recording systems to the card medium as they are. There are many. The reason is that the medium called card is deformed, rubbed,
While normally exposed to the harsh conditions of pressure, radiation, moisture, etc., disk-type media solve this problem by housing the disk in a rigid cartridge.

As an example of the DRAW format, there are low melting point metals such as tellurium, bismuth, and aluminum, and alloys mainly containing them. These materials have an advantage that the read signal of the recorded information and the control signal are high in intensity because the optical high reflectance is obtained, and the reliability of the storage system is high. Further, the sensitivity of this recording material is not necessarily high as a heat mode material because of its high thermal conductivity, but it is compensated by the technical output of the laser output currently obtained and the optical system in the subsequent stage. However, in the recording method using these metal-based materials, the melted portion is eliminated in the periphery due to the difference between the surface tension of the melted metal portion and that of the solidified portion in the periphery due to the temperature rise from the locally supplied laser energy. It is based on the principle that a pit is formed in that part after cooling. Accordingly, one of the recording layers composed of these metal materials is in contact with the substrate, and the other is provided with a free space. Alternatively, in this case, it is not hindered to further form a protective layer in contact with the recording layer, but since an excessively thick protective layer at this time lowers the recording sensitivity, this protective layer is formed as thin as possible. Furthermore, the other side of the protective layer is arranged facing the free space, as it is not. Further, when forming a shape as a disk using these materials, the spacer portion must be processed separately or integrally with the substrate in order to set the above-mentioned free space. Since the disc itself cannot withstand the environment such as pressure and deformation due to the free space constructed here, all the optical discs currently marketed are contained in the cartridge. Yet another problem is that processing of metal material on the recording layer requires vacuum technology such as vacuum deposition, sputtering, and CVD, so that mass production and development of card technology, which is premised on issuing, poses a productivity problem. I will end up.

Another example of the DRAW format is an organic dye. Although organic dyes can freely design the absorption spectrum on the dye side according to the wavelength of the light source used for optical recording, and the melting and decomposition temperatures are relatively high compared to the metal materials described in the previous section, this drawback is sufficient. It has sufficient thermal conductivity characteristics to make up for it, and has the advantage of using it as a recording material for DRAW. Further, dyes can be processed as a coating material by dissolving them in a solvent as they are as dyes and dispersing them in an appropriate dispersion medium as pigments, so that it can be said that they exceed metal materials even in consideration of suitability for mass production.
For this reason, organic dyes such as anthraquinone dyes, naphthoquinone dyes, triphenylmethane dyes, carbocyanine dyes, merocyanine dyes, xanthene dyes, azo dyes, azine dyes, thiazine dyes, oxazine dyes, phthalocyanine dyes, and squarylium dyes are used. Is proposed. However, the principle of the recording method is the same as in the case of the metal-based material described in the previous section, that is, the recording layer composed of the dye alone or the binder such as the thermoplastic resin is heated and melted by the laser energy locally supplied. The pits are formed due to the difference in surface tension from the peripheral area. As another change, an example has also been proposed in which a heated organic substance is decomposed and a coating layer covering the recording layer is pressed to cause deformation to form a pit. However, although there are some differences between the two, one surface of the recording layer faces a free space, and when the recording layer is further provided with a protective layer or a coating layer, these layers are The other surface is opposite to the free space as in the case described in the previous section, and this free space is set by using the spacer as the disk medium. Therefore,
Even if a DRAW medium using an organic dye is used, the disk medium is contained in a solid cartridge, and there are many problems in applying it to an additional writable optical card as it is.

〔Purpose〕

The present invention has been made in view of the above-mentioned problems of the conventional technology, and is an optical recording medium of DRAW format,
Its main purpose is to provide an optical card that is not affected by deformation and the like. Another object of the present invention is to provide an optical card with less reading error by obtaining recording with large contrast. Another object of the present invention is to provide an optical card which is less susceptible to changes due to radiated light or moisture.

〔Overview〕

The present invention provides an optical recording layer comprising a thermoplastic resin layer and a dye layer provided in contact with the thermoplastic resin layer in a card substrate, and the dye layer absorbs in a solid state at a wavelength of a recording light source. An optical card characterized by containing a pigment whose absorption intensity in a state of permeating the resin is greatly different from that in a solid state.

[Detailed Description of the Invention]

 The present invention will be described in detail below.

The basic principle of optical recording and reading of an optical card according to the present invention is as follows.

Regarding organic pigments, especially dyes, the history of research from synthesis to physical properties and dyeing methods is old and many findings have been obtained. Among the various physical properties, the solvent effect in the absorption spectrum of the dye and the association of the dyes are particularly relevant in the present invention. As is well known, the former is development in which the shape of the absorption spectrum and the maximum absorption position of the dye change depending on the polarity of the solvent, and the latter changes the association state of the dye depending on the concentration of the dye and the spectral curve It represents changing. In addition, even if the same dye as seen in dyeing of a resin typified by fibers, the hue changes due to the difference in the resin to be dyed is also included as one form of the solvent effect here. I can think. By the way, most of the research subjects that have been conducted so far have been dye behavior in a solution state. Therefore, as a result of diligent studies on the behavior of the dye in the solid state, the present inventor came to the present invention by paying attention to the inhalation spectrum in the solution state and that in the solid state.

In many cases, the absorption spectrum of the dye in the solid state is different from that in the solution state, and the absorption maximum position is shifted to the long wavelength side or the short wavelength side. Further, the absorption edge has the same change. These developments are found for both transmission and reflection absorption spectra. The cause of such a phenomenon is not clear in many cases, but the aggregated state of dye molecules in the solid state, that is, crystalline / amorphous or adsorption, or ionic dye, its ion dissociation or complex formation It seems that the problems are intricately intertwined.

By the way, the basic requirement of the optical recording medium is that the difference in the transmittance or the reflectance is caused by the optical means. Therefore, if the above-mentioned spectral change can be achieved by using any constitution, it can be provided as the optical recording medium. . That is, one of the possible configurations is to provide a solid layer of dye in contact with a thermoplastic resin as shown by the present invention. When energy such as laser light is supplied to the recording layer having such a structure and the temperature rises, the dye sublimes or melts and penetrates into the thermoplastic resin. Needless to say, the spectrum in this state corresponds to the spectrum in the above-mentioned solution state, and thereby the basic requirements of the optical recording medium are satisfied. Moreover, in this structure, since the dye sublimated or melted penetrates into the resin, it is not hindered to provide the protective layer on the other surface of the dye layer.
The thickness of this protective layer cannot exceed a certain value in conventional DRAW media with pit formation because it reduces its sensitivity, and it must be strictly controlled in manufacturing. In the structure according to the invention, the thickness of the protective layer is not particularly limited because it is not related to the sensitivity of the recording layer, and it has an advantage that it can be manufactured under simple control in manufacturing. Further, as the protective layer, it is possible to protect the recording layer with a film, a sheet or the like via an adhesive layer or the like. Therefore, the air gap that has been conventionally required in the DRAW medium becomes unnecessary by using this configuration.
In addition, DR for near-infrared light that corresponds to conventional semiconductor lasers in particular
All of the organic dyes proposed for AW are those that have absorption in the near infrared in a solution, and therefore many compounds are physically unstable, such as the light resistance of the dye. . However, according to the study by the present inventor, even if the dye has an absorption edge of the spectrum in the visible state in the solution state, in the solid state, there are many dyes whose absorption edge extends to the near infrared region. Dyes can be employed according to the constitution of the present invention. That is, since the absorption maximum wavelength, which is usually selected as reference data for selecting a dye, was measured in a solution, a physically stable dye that was not a target of the conventional selection is newly added by the present invention.
It can be said that the range of selection of dyes has expanded since it can be applied as an application dye.

Although the function can be recognized by using a thermosetting resin as the resin that can be used for the optical recording layer of the present configuration, a thermoplastic resin is more preferable in view of processability, recording sensitivity, and a range of selectable dyes. preferable. Specifically, saturated polyester, unsaturated polyester, polymethyl methacrylate, nylon, polyurethane, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyvinyl alcohol, polybutadiene, polyethylene, polypropylene, polycarbonate and blends or copolymers of these resins. Polymers can be used. Of course, the selection of the resin cannot be determined by the resin alone because there are problems of matching the hue (spectrum) with the dye and penetrating the dye as described above.

The dye that can be used in the dye layer of this configuration is not particularly limited as long as it has absorption in the solid state at the wavelength of the recording light source and greatly differs in absorption intensity in the state of being penetrated into the resin. Polychromatic dyes, especially dichroic dyes, are preferred as embodiments of the present invention. The dichroic dye is a dye having different absorption ability depending on the vibration direction of the electromagnetic wave incident on its molecular coordinate. In recent years, its application to a guest / host type liquid crystal display has attracted attention. Is changing the orientation direction, and
It is a reversible process. On the other hand, the present invention is different in that it is an irreversible process which is a change from the oriented state to the non-oriented state. That is, the dichroic dye is first placed in an oriented solid state and then penetrated into the resin,
The dye molecules are dissolved to make them non-oriented. As the dichroic dye, preferably used are anthraquinone dyes used for guest / host liquid crystal displays, and azo dyes such as diazo, triazo, and tetraazo, but the dyes are not limited thereto. However, a thiazine-based dye such as methylene blue and a triallylmethane-based dye such as Kayanol cyanine 6B (manufactured by Nippon Kayaku Co., Ltd.) exhibit dichroism sufficient for the present invention. Also,
Polychromatic dyes other than the dichroic dye system can also be used.

There is no specific method for producing a solid layer in which the dye molecules in the initial state are oriented. Regarding the method for forming the solid layer of the dye, it is possible to use a coating technique such as spin coating or roll coating by dissolving in a suitable solvent. At that time, it is often difficult to uniformly coat the pigment alone, but in that case, it is not hindered to add a small amount of a resin component to form a coating liquid in order to improve the coatability. . This is not so different from the absorption spectrum of the dye layer in the case where the resin content is small in the composition ratio of the dye content and the resin content, and that of the dye layer consisting of the dye alone, and the resin content works when the resin content is 20% or less. When a resin content of more than 20% is added, the dye layer shows a liquid-state spectrum rather than a solid-state spectrum and cannot be used. More preferably, the resin content is 10% or less. As for the orientation method, it can be oriented by a mechanical method. As a method for simultaneously performing film formation and orientation, a Langmuir-Blodgett method, a vacuum deposition method, or the like can be used. In particular, the latter has a wide range of applications because dyes and pigments having low solubility can be formed into a film. Alternatively, by utilizing the adsorption property of the dye, it is possible to achieve the purpose by only ordinary coating by combining with an appropriate resin. In this case, the combination of the polarity of the resin forming the thermoplastic resin layer and the polarity of the dye forming the dye layer must be selected.

The card configuration will be described below with reference to the drawings, but the present invention is not limited to the following embodiments.

FIG. 1 shows an example of a card structure, which is an optical card 1 in which an optical recording layer 2 is embedded. The recording layer 2 is composed of a thermoplastic resin layer 4 and a dye layer 5. If the thermoplastic resin layer 4 has a high light-transmitting property, it may not be installed in this order. The recording layer 2 is protected from the physical environment by the protective sheet 8. The protective layer 6 can be provided when the adhesive layer 7 is provided, if necessary. In some cases, the substrate 3 may have a preprocessed recording such as a tracking groove. FIG. 2 shows another example of the card structure. The optical recording layer 2 is manufactured on the auxiliary first substrate 10 to form the recording member 12, which is used as the second substrate 11 and the protective sheet 8. It is the optical card 1 which is sandwiched between and and integrated by the adhesive layer 7. The layer 9 is a surface-hardened layer.

〔Example〕

A photoresist (AZ-1350) is applied on a glass plate (BK-7) by a spin coater. After that, it is exposed by an argon laser beam that has been modulated according to the guide groove signal by a cutting machine, and then developed, and the groove width is 0.8 μm and the track pitch
A guide groove original plate having a groove depth of 2.5 μm and a groove depth of 0.07 μm was prepared. Next, apply 0.05 to 0.1 μm to this original plate by the nickel stamper method.
After forming the conductive film of No. 3, a stamper having a thickness of 0.3 mm was prepared by nickel electroforming. After that, apply a photosensitive resin (acrylate type) to the stamper, and 0.40 mm for 100 m
A polycarbonate substrate having a size of m × 80 mm was pressed and irradiated with ultraviolet rays to be cured to form a guide groove in the polycarbonate substrate.

On the other hand, the spectrum a of the dichroic dye 1, 1, 5, 5, -tetrakis (p-dimethylaminophenyl) -2,4-pentadienol perchlorate in an acetone solution
FIG. 3 shows the spectrum b of the solid film of the dye provided by coating on a glass substrate as a reference. It was found that the solution state spectrum of the dye is different from that in the solid state.

Then, the dye was used as a heat mode recording material, and a methanol solution of the dye was applied by a spin coater to the guide groove forming surface of the polycarbonate substrate in which the guide groove was formed to provide a dye layer having a thickness of 0.1 μm. Further, a thermoplastic resin layer having a thickness of 3 .mu.m was formed on this by an aqueous solution of polyvinyl alcohol by the same spin coater. On the recording layer surface of the optical recording medium created in this way, with a thickness of 0.30 mm, which is the card substrate, through an epoxy adhesive (araldite).
An optical card was prepared by bonding 100 mm x 80 mm size hard white PVC and curing and punching into a card size of 85.5 mm x 56 mm. The optical card created in this way can be used as a semiconductor laser (9 m
When recording at W, 2 MHz), the above dye penetrated into the resin and a recording mark was generated. When reproduced with the same laser of 1 mW, a good signal was obtained.

〔The invention's effect〕

 The effects of the present invention will be described below.

1. By removing the air gap layer, a recording layer that is resistant to external forces such as pressure and deformation was obtained, enabling processing to card media.

2. A recording medium with a high contrast can be obtained when reading the record.

3. The reliability of the recording medium is improved because the more stable dye can be selected.

[Brief description of drawings]

1 and 2 show an example of the card structure of the present invention. Further, FIG. 3 shows a spectrum curve of 1,1,5,5, -tetrakis (p-dimethylaminophenyl) -2,4-pentadienol perchlorate. 1: Optical card 2: Recording layer 3: Card substrate 4: Thermoplastic resin layer 5: Dye layer 6: Protective layer 7: Adhesive layer 8: Protective sheet 9: Surface hardened layer 10: First substrate 11: Second Board 12: recording material

Claims (2)

[Claims] 1. An optical card comprising an optical recording layer embedded in a card substrate, wherein the optical recording layer comprises a resin layer and a dye layer provided in contact with the resin layer, and the dye layer further comprises a recording layer. An optical card characterized by containing a dye that absorbs in a solid state at a wavelength of a light source, and has an absorption intensity greatly different from that in a solid state when it penetrates into a resin. 2. The optical card according to claim 1, wherein the dye layer contains 20% or less of a binder.