JPH01251442A - Optical card - Google Patents

Abstract

PURPOSE:To secure sufficient mechanical strength, to suppress the lowering of recording sensitivity, and to obtain superior weatherability by providing low tungsten oxide layers on an optical recording layer by laminating. CONSTITUTION:The optical recording layers 2 are formed on a transparent substrate 1 by laminating, and the low tungsten oxide layers 3 are formed being laminated on the surfaces of the layers 2 by vacuum vapor deposition, and card substrates 5 are adhered on the layers 3 via a bonding agent 4 by laminating. And it is possible to prevent a reactive gas or water from invading in the layer 2 by bringing the layer into contact with the layer 2, and to prevent the layer 2 from being deteriorated. Also, the layer 3 is constructed in porous structure by forming oblique vapor-deposition, and the piece of an optical recording material splashed from the layer 2 at the time of forming a pit can be attracted by its pore.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to optically writable destination cards.

[Prior Art] In recent years, as the magnetic cards widely used in various fields have been required to have higher functionality, optical cards have been proposed as a card medium with a larger storage capacity than magnetic cards. Among them, optical cards that can be used for additional writing are seen as promising because of their wide range of uses.

As a method of optically recording written information, direct
There is a read-after-write (DRAW) format. This type of recording method is heat mode recording, in which digital recording is performed by irradiating the recording material with synchrotron radiation such as a laser beam as a heat source to cause physical and chemical changes to the recording material. It has the advantage that the record will not disappear unless it is heated to a temperature that permanently deforms it.

One example of the DRAW format is one that uses a recording medium provided with an optical recording layer made of a low melting point metal such as tellurium, bismuth, aluminum, or an alloy thereof. In this case, there is an advantage that the signal strength is high because the metal forming the optical recording layer has a high reflectance. Also, DRA
Another example of the W format is one using a recording medium provided with an optical recording layer made of an organic dye. In this case, organic dyes have the characteristics that the absorption spectrum of the dye side can be freely designed to correspond to the wavelength of the light source used for optical recording, and that they have a high coefficient of thermal expansion.As organic dyes, anthraquinone, Examples include naphthoquinone series, triphenylmethane series, carbocyanine series, merocyanine series, xanthine series, azo series, azine series, thiazine series, oxazine series, phthalocyanine series, and squarylium series. The method of recording using an optical recording layer formed of these metals or organic dyes involves irradiating the recording layer with a spot of laser light, heating the laser-irradiated area of the optical recording layer, and melting it. However, due to the difference in surface tension between the melted laser beam irradiated portion and the thinned portion around the melted laser beam irradiated portion, the laser beam irradiated portion is excluded from the periphery to form a hole, that is, a bit.

Conventionally, it has been considered to manufacture an optical card capable of additional writing by applying such a RAW format recording medium.

[Problems to be Solved by the Invention] However, when applying the above-mentioned DRAW format to produce an optical card capable of additional writing, there are the following problems. That is, in this type of recording medium, recording is performed by forming bits by melting the portion of the optical recording layer that receives the laser beam and expelling it to the surrounding area. For this reason, in general, in this type of recording medium, one side of the optical recording layer is in contact with the substrate, but the portion of the optical recording layer that is melted by laser beam irradiation is placed adjacent to the other side of the recording layer. A space layer is provided to ensure space for the air to escape. The recording medium is manufactured in the shape of a disk and housed in a strong cartridge to protect it from external forces.

However, cards as recording media are generally used as cash cards or credit cards and are carried around in wallets, etc., and there is a risk of deformation or damage due to the application of various external forces. It needs to have enough strength to withstand, and it needs to be thin for the appearance of the card. For this reason, if a card is manufactured by applying the structure of a conventional DRAW-format recording medium that has a space layer adjacent to the recording layer, the strength of the card will decrease and the card will become thicker. It is not possible to manufacture an optical card by adopting the structure of the medium as it is.

Therefore, in order to apply the D'RAW format to produce an optical card that can be additionally written to, each layer such as the substrate, recording layer, and other transparent layers must be completely covered without providing a space layer adjacent to the recording layer. Consideration is being given to adopting a structure that allows them to stick together.

However, with a DRAW format optical card having such a close contact structure, there is a problem that it is difficult to maintain the recording sensitivity constant for a long period of time after recording, and the recording sensitivity may decrease.

The present invention has been made based on the above-mentioned circumstances, and is a DRAW that has sufficient mechanical strength, can suppress a decrease in recording sensitivity, and has good weather resistance.
The purpose is to provide an optical card that adopts this format.

[Means and effects for solving the problem] In order to achieve the above object, the optical card of the present invention is an optical card in which an optical recording layer is laminated on a transparent substrate, and a low tungsten oxide layer is provided on the optical recording layer. It is characterized by being provided in a laminated manner.

The basic structure of the optical card of the present invention will be explained with reference to FIGS. 1 and 2.

In the figure, 1 is a transparent substrate, which is made of a material such as polymethyl methacrylate. This transparent substrate 1 has an optical recording layer 2.
are formed by stacking them. The optical recording layer 2 is formed by vacuum-depositing the metal material described above on the surface of the transparent substrate, or by coating the surface of the transparent substrate 1 with the organic dye described above. A low tungsten oxide layer 3 is laminated on the surface of the optical recording layer 2 by vacuum deposition. Further, a card substrate 5 made of synthetic resin or the like is laminated and bonded to the low tungsten oxide layer 3 via an adhesive 4 such as an epoxy adhesive.

Here, the low tungsten oxide layer 3 is formed on the surface of the optical recording layer 2 by an EB evaporation method, particularly an oblique evaporation method, after reducing and firing a tungsten pellet.
It can be expressed as O3-x (0<X≦1). The appropriate thickness of the low tungsten oxide layer 3 is in the range of 20 to 100 nm. This low tungsten oxide layer 3 can be considered to work as a kind of reducing agent, and when this low tungsten oxide layer 3 comes into contact with the optical recording layer 2, reactive gases and moisture enter the optical recording layer 2. It has a function as a protective layer that prevents the optical recording layer 2 from deteriorating. For example, it has the role of preventing oxidation of the optical recording layer 2. In addition, although the low tungsten oxide layer 3 is porous itself, it becomes a very porous structure when formed by oblique vapor deposition, and when the optical recording layer 2 is irradiated with laser light to form pits, the optical recording layer 3 Its many pores absorb fragments of optical recording material scattered from the surface. It is considered that the low tungsten oxide layer 3 acts as a buffer layer in this way, thereby reliably suppressing the decrease in recording sensitivity of the optical recording layer 2. In this way, the low tungsten oxide layer 3 has the functions of both a protective layer and a buffer layer, and after recording on the optical recording layer 2 with laser light, it maintains a constant recording sensitivity for a long period of time and prevents the recording sensitivity from decreasing. It has a pressing function.

Therefore, the optical card constructed in this way includes a transparent substrate 1, an optical recording layer 2, a low tungsten oxide layer 3, and a card substrate 5.
Since the cards are laminated and bonded together, they have sufficient mechanical strength so that there is no risk of damage or deformation due to various external forces during use, and the card can be made thin enough to be used as a card. You can have it. Further, due to the function of the low tungsten oxide layer 3, there is no decrease in recording sensitivity due to the close contact structure, and a constant sensitivity can be maintained over a long period of time.

[Example] Example 1 Tellurium was EB-steamed onto a transparent substrate made of polymethyl methacrylate on which predetermined tracking grooves were formed, and a thickness of 30 nm was deposited.
An optical recording layer is formed with a film thickness of m, and then low tungsten oxide, which is obtained by reducing and firing tungsten oxide, is deposited on the optical recording layer using E.
A low tungsten oxide layer is formed by oblique evaporation of B evaporation,
Next, a card substrate was bonded to the low tungsten oxide layer using a flexible epoxy adhesive to produce an optical card with a close contact structure. This graph shows the change in the write threshold when this optical card is stored under semiconductor laser (humidity) conditions.The solid line is for an optical card that has only an optical recording layer (tellurium) and no low tungsten oxide layer. The broken line shows the case of an optical card in which a low tungsten oxide layer is formed.

According to this diagram, optical cards with a low tungsten oxide layer have lower initial sensitivity than those without a low tungsten oxide layer, but maintain stable sensitivity over a long period of time and have good storage stability. I understand. Fig. 4 is a diagram showing the relationship between writing energy and recording contrast, where the solid line shows the case of an optical card in which a low tungsten oxide layer is formed on the optical recording layer (tellurium), and the broken line shows the optical recording layer (tellurium). The figure shows the case of an optical card with a silicon oxide layer formed on it. According to this diagram, it can be seen that the optical card in which a low tungsten oxide layer is formed has a lower recording sensitivity than the case in which a silicon oxide film is formed.

Example 2 An optical recording layer was formed by applying a material prepared by dissolving a cyan dye in a solvent onto the same transparent substrate as in Example 1 using a spinner, and the work was then carried out under the same conditions as in Example 1 to produce an optical card. . Although the resulting optical card showed a slight decrease in sensitivity, it was able to perform good recording and had improved weather resistance.

[Effects of the Invention] As explained above, according to the present invention, since the low tungsten oxide layer is laminated in the optical recording layer, each layer is laminated closely and the whole is thin and has sufficient mechanical strength. It is possible to obtain a record with high contrast while suppressing a decrease in sensitivity, and furthermore, it is possible to obtain an additionally writable destination card that employs the DRAW format and has excellent weather resistance.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the basic structure of the optical card of the present invention;
FIG. 2 is a plan view of the same, FIG. 3 is a diagram showing changes in sensitivity after recording on the optical card, and FIG. 4 is a diagram showing a decrease in recording sensitivity of the optical card. DESCRIPTION OF SYMBOLS 1... Transparent substrate, 2... Optical recording layer, 3... Low tungsten oxide layer, 5... Card substrate. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] An optical card comprising an optical recording layer laminated on a transparent substrate, characterized in that the optical recording layer is laminated with a low tungsten oxide layer.