JPS61203450A - Optical recording medium - Google Patents

Abstract

PURPOSE:To enable rewriting at normal temp. by laminating plural information recording layers contg. photochromic compds. different in light absorption wavelength region or an information recording layer contg. a mixture of these compds. CONSTITUTION:Light sources 1-3 emit lights of specified wavelengths, such as 550nm, 600nm, and 650nm, on receiving input signals A, and after being condensed 4, irradiate an information recording medium 5. The output of the medium 5 is divided 10, and converted 11, 12, 13 into output signals of 3 bits. The medium 5 is obtained by laminating the information recording layers 7, 8, 9 contg. the photochromic compds. corresponding said wavelengths, or the recording layer contg. the mixture of the photochromic compds. may be used. The layers 7, 8, 9 are irradiated with an erasing lamp 14 to develop colors, and thus initialized. When a signal is input, the color at the part corresponding to it is erased, and the signal is written. When the information is read out, the light sources 1-3 are turned on to irradiate at a time, and when they are erased, the medium 5 is irradiated with the lamp 14, thus permitting a multi- wavelength recording system rewritable at normal temp. to be fabricated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical information recording medium, and particularly to an optical recording medium capable of high-density information recording.

Conventional technologyAs a means to further increase the density of optical information recording,
Attempts have been made to record multiple bits of information per light spot, that is, wavelength multiplexed recording. Techniques for this purpose include, for example, those that utilize the chemical hole burning phenomenon (for example, Japanese Patent Application Laid-Open No. 58-51366), or the combination of a recording layer group consisting of many types of dyes and a group of light beams corresponding to each dye. (For example, Japanese Patent Application Laid-open No. 152528/1983) is known.

Problems to be Solved by the Invention However, the former method requires a large-scale cooling device because the phenomenon of chemical hole burning can only be used at extremely low temperatures, and the fruiting device is expensive and has not yet been put into practical use. .

However, since the latter utilizes an irreversible chemical reaction of dyes, it was impossible to erase or rewrite written information.

Means for Solving the Problems An information recording layer is provided on a substrate by using several types of photochromic compounds having different light absorption wavelength regions, and by laminating or mixing them.

Effect: When the optical recording medium of the present invention is irradiated with a light beam of a certain wavelength,
a recording layer that absorbs light of that wavelength among the irradiated parts;
Alternatively, only components within the same layer that absorb light of that wavelength cause a photochromic reaction, and information is written. Furthermore, by simultaneously applying light of several different wavelengths, several pits can be written three-dimensionally at the same time. Furthermore, when irradiated with a light beam that causes a photochromic reaction in the opposite direction to the above,
The irradiated area returns to its original state and the information is erased. By repeating these operations, it is possible to write, erase, and rewrite information. Q Examples Many photochromic compounds are known, including spiropyran, fulgide, and thioindigo, and any of them can be applied to the present invention. However, examples constructed using three types of spiropyran are described below.

Embodiment 1 FIG. 1 shows an example of an information recording apparatus mainly using the optical recording medium of the present invention. In the figure, 1 to 3 are respectively 550 nm,
A light source that emits light with wavelengths of 600 nm and 6150 nm (
(preferably a laser) and 0N- depending on the input signal.
Turn off. Reference numeral 4 denotes a light converging section, which has a disk shape with information recording layers 7, 8, and 9 on top, and rotates. 7 is 6-nitro-
1/, 3/, 3/-trimethylspiro[2H-
1-benzopyran-2°2'-indoline], and preferentially absorbs light of 560 nm.

8 is an information recording layer consisting of 5-promo17,3/-dimethyl-6-medoxy8-nitro-37-phenylspiro (2H-1-benzopyran-2,2'-indoline), and gives priority to light of 600 nm. 9 is 1
, 3'-dimethyl-6'16-sinitro 8-methoxy-3'-phenylspiro (2H-1-benzopyran-2
, 2'-indoline] with an information recording layer of 650 n
It preferentially absorbs light of m. Reference numeral 10 denotes a light splitter, which splits the mixed light beam that has passed through the information recording medium into the original three types of light beams. Converters 11 to 13 correspond to the respective light beams, and output binary electric signals corresponding to the strength of the light beams. Reference numeral 14 denotes an erasing light source that irradiates the entire surface of the information recording medium 5 with ultraviolet light having a wavelength of 300 to 400 nm.

The operation of the information recording device having the above configuration will be explained.

Initialization> Immediately after the creation of the information storage medium, all of the information recording layers 7 to 9 were colorless, and there was no absorption in the region of 400 to BOO nm. When irradiated with the erasing lamp 14, all of layers 7 to 903 caused a photochromic reaction and became colored, and as shown in the graph in the left column of FIG. 2, absorption peaks were formed in each specific region. This state was defined as the initial state.

For example, if you want to record only on the information recording layer 8, light source 2
Apply an input signal that turns ON only. Only the portion of the information recording layer 8 that had been exposed to the light was decolored, and the light absorption peak disappeared, as shown in the graph in the right column of FIG. In other words, 11" of information is written in binary code at one point on the information recording layer 8.It is also possible to record on other information recording layers in the same way, with 3 pits per spot of the light beam. information has been written.

Readout> When reading, use three types of light sources 1 to 3 at approximately 1
It was irradiated all at once at an intensity of /10. The light passing through the information recording medium depends on the colored or colorless state of the information recording layers 7 to 9.
The absorption of the corresponding rays is different.

After this was distributed by the distributor 10, it passed through the converters 11 to 13, and it was possible to obtain 3 bits of information at the same time.

Erasing> Erasing could be performed using the same method as initialization.

Example 2 A second example of the present invention will be described. It is basically the same as FIG. 1, and the difference from FIG. 1 is that the information recording layer is made of one layer. That is, it has one information recording layer made of a mixture of the three types of photochromic compounds used in the information recording layer of Example 1.

The other configurations and operating methods are exactly the same.

Effects of the Invention By carrying out the present invention, it is possible to provide an information recording medium that can operate at room temperature and performs high-density information recording using a rewritable wavelength multiplexing recording method.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the configuration of an information recording device using an optical recording medium according to an embodiment of the present invention, and FIG. 2 is an absorption spectrum of each information recording layer in the initial state of the medium and during writing. . 1 to 3...Light source, 4...Concentrator, 6.
...Information recording medium, 7-〇...Information recording layer, 10...Distributor, 11-13...
Converter, 14...Elimination source. Name of agent: Patent attorney Toshio Nakao and 1 other person
1 Figure 2 Initial deafness = 5 sentence length (yn
n)

Claims (1)

[Claims] A plurality of information recording layers containing photochromic compounds each having a different light absorption wavelength region are laminated on a substrate, or an information recording layer containing a mixture of a plurality of photochromic compounds each having a different light absorption wavelength region is provided on a substrate. optical recording medium.