JPS63153740A - Optical recording medium - Google Patents

Abstract

PURPOSE:To prevent deterioration with age by laminating a recording medium film for writing and reading out by a laser beam and protective layer for the recording medium successively on a card substrate and further laminating a light shielding layer which shields light except the laser beam thereon. CONSTITUTION:The recording medium film 2 which consists of tellurium oxide to about 100nm thickness and is sensitive only to the laser beam of a specific wavelength is formed by vacuum deposition on the surface of the plastic substrate 1. The protective layer 3 consisting of an epoxy resin and having 50-100mum thickness is then provided on the surface thereof and further the light shielding layer 4 consisting of near IR light transparent black glass is depositied on the surface thereof. The characteristic to allow the transmission of the semiconductor laser beam of 830nm wavelength to be used for writing and reading out and to shut off the other light is obtd. by this constitution. As a result, the constitution of the recording medium which is not deteriorated by general light fluorescent lamps, etc., except the laser beam light and is extremely stable with age is permitted.

Description

[Detailed description of the invention] 〔overview〕 In optical cards, etc. used as optical recording media.

A laser beam of a specific wavelength is used to write or read optical information.

The present invention is applicable to light energies other than laser beams of specific wavelengths, such as natural light and fluorescent lamps.

By forming a light blocking layer that blocks this light, deterioration of the optical recording medium over time is prevented.

[Industrial application field]

The present invention relates to an optical recording medium that can be used as an optical card or the like for recording optical information.

Optical recording media are used in optical cards and optical disks because they are capable of recording a larger capacity of information than conventional magnetic recording media.

Such an optical recording medium physically changes an amorphous structure of the medium into a crystalline structure using thermal energy generated by a focused beam from a semiconductor laser, and the difference in optical reflection characteristics is recorded in bits of optical information (information There are some methods that use the beam irradiation section to melt or remove the recording medium.

In any case, the optical recording medium is formed by forming a vapor-deposited film of a low melting point metal such as bismuth or tellurium to an appropriate thickness, which has a high efficiency of photothermal conversion by irradiation beam energy, and serves as a recording medium film.

[Conventional technology]

FIG. 2 is a sectional view showing an example of the configuration of a conventional optical recording medium. The configuration will be explained according to the diagram.

In FIG. 2, a plastic carrier l with excellent flatness is coated with a film of low melting point tellurium oxide (Tea) of about 1100 nm on its surface as an optical information recording medium film 2.
A film is formed to a certain extent.

Next, the surface protective layer 3 of the recording medium film is formed by depositing a photopolymer resin 3 to a thickness of about 50 to 100 μm on the surface of the recording medium H*2.

Information is recorded on the optical recording medium by irradiating the surface of the substrate with a focused optical beam 7 from a semiconductor laser of a specific wavelength in a pulsed manner, and changing the beam power or irradiation time to change the film structure of the recording medium film 2. Optical information is written by changing the material from amorphous to crystalline. However, reading the written information.

This can be done by detecting the strength level of the amount of light reflected from the recording medium due to the change in the film structure.

[Problem that the invention seeks to solve]

However, conventional optical recording media cannot be exposed for long periods of time to environments where light energy other than laser light of a specific wavelength used for recording or reading recorded information, such as general light such as sunlight or fluorescent lamps, acts. It is known that if the recording medium is left unattended, the photosensitivity, etc. of the recording medium deteriorates. In connection with this, for example, when reading written optical information, a predetermined detection output level cannot be obtained, which may even lead to malfunction of optical information reading, reducing operational reliability.

An object of the present invention is to prevent the structure of a recording medium film from changing over time due to light energy other than a specific laser wavelength.

[Means for solving problems]

FIG. 1 is a block diagram (perspective view) of an optical recording medium to which the present invention is applied to an optical card.

An optical information recording medium film in which optical information is written or read using a laser beam of a specific wavelength using a card substrate as a carrier 1.2. A protective layer 3 of the recording medium 2, a light blocking layer 4 that blocks light energy except for a laser beam of a specific wavelength for writing or reading optical information. The optical recording medium 5 is formed by sequentially laminating the following layers.

[Effect]

According to the optical recording medium of the present invention, which is provided with a light blocking layer that blocks light energy other than a specific laser beam, even if exposed for a long time under conditions where general light acts, which has been a problem in the past, the light energy can be protected. teeth.

This is blocked by the light blocking layer, and deterioration of the optical recording medium is extremely reduced, resulting in the formation of an optical recording medium that is stable over time.

〔Example〕

Hereinafter, an explanation will be given with reference to FIG. 1, a perspective view of an optical card, which is an example of the optical recording medium 5.

In the figure, polycarbonate with a flat surface.

Alternatively, the surface of the plastic carrier 1 made of polymethyl methacrylate or the like is coated with 2, for example, tellurium oxide TeO, to a thickness of about 1100 nm by vacuum evaporation as the recording medium film 2.
The film is formed to a certain extent.

The recording medium film 2 may be formed on the entire surface of the plastic substrate 1, or may be formed in a plurality of stripes as appropriate on only one surface of the substrate surface.

Furthermore, a photopolymer protective layer 3 of epoxy resin composition is deposited on the surface to a thickness of 50 to 100 μm.

Thereafter, a light blocking layer 4 of 100-500 μm is applied.

The light blocking layer 4 has a light selection characteristic of transmitting the semiconductor laser beam light having a wavelength of 830 nm for writing optical information, but blocking other light. Near-infrared transmitting point glass (product number: 03FCG115) manufactured by Rex Corporation is suitable for this purpose.

The tellurium oxide film 2 changes from amorphous to crystalline due to the irradiation energy of the laser beam of the specific wavelength for writing optical information. Along with this, the optical recording medium film 2 changes from an initial low light reflectance state to a high light reflectance state.

This change is used to record bits of optical information.

Although the optical recording medium embodiment described above exemplifies an optical card as a carrier, it goes without saying that the light blocking layer 4 of the present invention can also be applied to an optical disk formed on a disc-shaped carrier.

Moreover, the effects of the light blocking layer 4 and the photopolymer protective layer 3 described in the embodiments do not change even if the order of lamination is changed.

Below, the results of experimental studies regarding the optical recording medium 5 having the light blocking layer 4 will be described.

The optical recording medium of the present invention having the light blocking layer 4 and the conventional optical recording medium not having the same were exposed to a desk for a long time (3000 It m) using a white fluorescent lamp as the general light.
000 hours), the optical recording medium without a light blocking layer showed a 20% decrease in readout output (reproducing output) for optical information recording, whereas the optical recording medium 5 provided with the light blocking layer of the present invention decreased by as much as 20%. Its effectiveness has been proven as no decrease in output was observed.

〔Effect of the invention〕

As explained above, the optical recording medium equipped with the light blocking layer of the present invention does not deteriorate when exposed to general light such as a fluorescent lamp, except for laser beam light for writing optical information or reading recorded information. , thus an optical recording medium that is extremely stable over time is formed.

If this is applied to an optical information recording card (optical card) or an optical disk, an optical recording medium with high operational reliability can be provided.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of the optical recording medium of the present invention. FIG. 2 is a cross-sectional view of a conventional optical recording medium. In the figure, 1 is a carrier (substrate), and 2 is a recording medium film. 3 is a protective layer, 4 is a light blocking layer. and 5 is an optical recording medium. , bu- (two

Claims (1)

[Claims] An optical information recording medium film (2) on which optical information is written or read by a laser beam of a specific wavelength using a card or disk substrate as a carrier (1), a protective layer (3) of the recording medium (2), an optical information 1. An optical recording medium comprising a light blocking layer (4) which blocks light energy other than a laser beam of a specific wavelength for writing or reading, which are sequentially laminated.