JPS59218634A - Writing and reading-out method of optical information recording medium - Google Patents

Abstract

PURPOSE:To obtain a writing and reading-out method of an optical information recording medium which has high sensitivity and withstands reading-out light by writing the information on an optical information recording medium having an org. dye recording layer exhibiting a metallic light-reflecting characteristic on a base plate with the light of the wavelength having higher optical absorption of the recording layer and reading out the same with the light of the wavelength having higher light reflectivity of the recording layer. CONSTITUTION:Information is written by the light of the wavelength having higher optical absorption on an optical information recording medium having an org. dye recording layer exhibiting a metallic light-reflecting characteristic on a base plate and the information is read out by the light of the wavelength having the higher light reflectivity. Any org. dye is usable as the dye for forming the recording layer as far as said dye exhibits a metallic light-reflecting characteristic. The dye which provides the metal-like reflection, that is, bronze brightness, exhibited in a specific light wavelength region and which has >=20%, more preferably 30% reflectivity to the laser wavelength used for writing and readingout is preferable in actuality. The org. dye is exemplified by a cyanine dye and merocyanine dye.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to a method for skipping reading from an optical information recording medium.

BACKGROUND OF THE INVENTION Various types of recording media have been proposed for use in information recording and reproducing apparatuses that record and reproduce information by irradiating laser light onto a rotating disc-shaped information recording medium. Among these, the optical information recording medium proposed by the present inventors uses an organic dye thin film that exhibits metallic light reflection (bronze luster) as a recording layer, so it has excellent sensitivity and resolution (therefore, a high S/N ratio). It also has the advantage of low manufacturing cost. However, the higher the sensitivity, the faster the deterioration with respect to the readout light.For example, if the sensitivity is 5mW, the readout power is 0.4mW.
However, it can be read repeatedly over 1 million times,
It is 2.5 mW, which is considerably lower with the same read power. For this reason, when writing information to a highly sensitive recording medium, it is necessary to lower the readout optical power, but if the readout power is lowered, the ratio of laser diode noise and optical sensor noise components increases (and the SA decreases). Therefore, there is a need for an information readout method suitable for highly sensitive optical information recording media.

Purpose The present invention has been made in view of the above-mentioned current situation, and its purpose is to provide a method for writing and reading an optical information recording medium that has high sensitivity and can withstand reading light.

Structure The present invention is an organic dye absorbing dye that exhibits metallic light reflection characteristics.
Kuttle and specular reflection are made by taking advantage of Kuttle's characteristic, that is, the fact that organic dye thin films exhibiting metallic reflection have specular reflection spectra on the longer wavelength side than the peak value of the absorption spectrum.

To explain this point in the case where a cyanine dye having the following structural formula is used as an organic dye, for example, the relationship between the absorption spectrum and the specular reflection spectrum of a thin film formed with this dye is as shown in FIG.

As is clear from FIG. 1, the recording medium having the organic dye film has an absorption spectrum peak at 800 nm, but a reflection spectrum peak of 890 ng. Therefore, 8
Writing information with 00 nm light provides optimal sensitivity, while reading information with 890 nm light provides the highest contrast.

Therefore, the writing/reading method of the present invention, which is applied to an optical information recording medium having an organic dye recording layer exhibiting metallic light reflection characteristics on a substrate, reduces the optical absorption of the recording layer when writing optical information. The purpose of this method is to use light with a high wavelength, and to use light with a wavelength that has a higher light reflectance of the recording layer when reading optical information.

The organic dye recording layer in the present invention is composed of an organic dye exhibiting metallic light reflection characteristics, either alone or in a mixture with other components such as a binder. It can be easily formed by coating and drying.

The organic dye forming the recording layer of the present invention may be any dye as long as it exhibits metallic light reflection characteristics. ), and in reality, the reflectance is 209b or more, preferably 3 for the laser wavelength used for writing and reading.
It is preferable to have 0 rice cakes. Representative examples of organic dyes include cyanine dyes and merocyanine dyes.

5. The laser beam used in the method of the present invention must be selected according to the absorption wavelength of the dye used, but He-Ne, which is relatively inexpensive, can be used.
Lasers or semiconductor lasers are preferred.

Furthermore, as shown in FIG. 2, the enrichment reading device used in the method of the present invention has an independent reading optical system (reading optical system) and writing optical system 2, but it is not possible to share the actuator portion, for example. can.

EXAMPLES The present invention will be further explained by the following examples, but the present invention is not limited thereto.

Example 1 -6= A 1.25% ethylene dichloride solution of the dye was added to 1.25% ethylene dichloride solution.
The mixture was coated on an acrylic plate with a thickness of 2 mm to form a thin film of approximately 500 layers, thereby obtaining a recording medium. The optical spectral characteristics of this recording medium are No. 318! As shown in U.

An 800 nm semiconductor laser was used for writing, and an 850 nm semiconductor laser was used for reading.

Linear velocity of 1.24 m, recording surface power of 2.5 m
W.

CJ, 6875 MH using light with a beam diameter of 1.4 μm.
I went with 'z. When reading was performed by reducing the recording surface power to 0.5 mW and reading with a bandwidth of 30 KHz''C, we obtained c, zN52+jB, but after repeating the reading several hundred times, the C/N decreased to 30 dB. decreased. Also, when reading at 0 or 1 mW, the C/N is 4
I couldn't get 5dBl. If the laser source for readout is 850 nm, the readout power will be Q, 5
A C/N of 52 clB was obtained at mW, and several hundred readings were performed. 7- 6... Motor, 4... Optical disk, 5... Rotating shaft.

Even after repeated testing, no decrease in c/H was observed.

Example 2 The same reading as in Example 1 was performed except that the dye in Example 1 was replaced with the above dye, and the same results were obtained.

Effects According to the method of the present invention, it is possible to prevent deterioration of an optical information recording medium due to read light.

[Brief explanation of the drawing]

FIGS. 1 and 3 are diagrams showing the relationship between the absorption spectra and reflection spectra of organic dyes according to the present invention, and FIG. 2 is a schematic diagram showing an example of the apparatus used in the method of the present invention. . 1...Reading optical system, 2...Writing optical system,
8- Patent Application University Rico Co., Ltd. - 9-

Claims (1)

[Claims] Information is written on an optical information recording medium that has an organic dye recording layer that exhibits metallic light reflection characteristics on a substrate using light with a higher wavelength of optical absorption, and information is written with light with a higher wavelength of optical reflectance. A method for writing and reading an optical information recording medium.