JPS6045485B2 - optical recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical recording medium for recording and reproducing information at high density using light, heat, etc. The present invention also provides an optical recording medium capable of high-density optical recording and reproduction in the near-infrared region.

Techniques for recording and reproducing high-density information using laser beams are well known.

As a recording medium used for such recording and reproduction, there is one in which a thin film mainly composed of tellurium oxide Te0x (0<x, <2) is provided on a substrate. (Unexamined Japanese Patent Publication No. 50-46317
Publication No. 1983-46318, Japanese Patent Application Laid-Open No. 1983-46318,
46319, U.S. Pat. No. 3,971,874), additional components include Pb0x5 (0<x, <1), 5
b0x0 (0<, <1.5), V0x7 (0<X7<
2.5) etc. are used. Such a recording medium can obtain a large change in transmittance when irradiated with a light beam for reproduction. However, there is a limit to the output of laser light sources that can be used when miniaturizing and simplifying recording and reproducing devices, and small He-Ne laser oscillation devices, semiconductor laser oscillation devices, etc. with an output of 20 liters or less are used. Record using,
For reproduction, a recording medium provided with a thin film containing TeOx (0<X<2) as a main component has insufficient sensitivity.

Furthermore, when information is reproduced by changing the amount of reflected light, a sufficient amount of change cannot be obtained. Considering the optical transmission efficiency of the optical system used in recording and reproducing devices, 50TrL, Jlclt
It is desirable that the state is changed by a He-Ne laser beam or a semiconductor laser beam having an energy density below, and that the optical characteristics thereof are significantly changed. The optical recording medium of the present invention improves conventional materials to improve sensitivity and changes in optical properties associated with recording.

3 In order to utilize the state change of the recording medium due to temperature increase due to light irradiation absorption, etc., as a method to increase the sensitivity, the main component TeOx, 0<x, <2.0 (Te02 melting point Tm ℃) There is a method of lowering the threshold temperature for state change by applying additive materials with low melting points.

For example, n0X20<X2<1.5 (n20 melting point T
m=300°C). On the other hand, there is a method of increasing the refractive index of the medium in order to increase the change in optical properties accompanying the state change, and for this purpose, an additive material with high ionic polarizability and high density is used.

For example, BlOx2, InOx2 (0x2<1.5)
etc.

In order to produce the recording medium in the present invention, a raw material obtained by adding at least one oxide of thallium, bismuth, and indium as an additive component to tellurium oxide as the main raw material is used as a raw material.

Using tellurium oxide TeO2 as the main raw material, thallium oxide Tl2O3, bismuth oxide Bl2O3,
Bi2O5, and indium oxide 1r1203,
At least one is then used as a raw material for an additive component. To construct the optical recording medium, a glass plate, polymethyl methacrylate resin,
A sheet or film made of synthetic resin such as polyvinyl chloride resin, polycarbonate resin, polyethyl terephthalate resin, etc. is used.

Further, it is also possible to use a material coated with an appropriate surface coating in order to adjust the surface thermal constant, etc. The main raw material tellurium oxide and the additive raw material oxide are powdered and mixed, and then melted in an air atmosphere in a quartz crucible or a platinum crucible. A few minutes is sufficient for the melting time. The mixed and molten raw material oxides are quenched in air to obtain a yellowish to black glassy substance. This mixed solid solution is powdered and used as a raw material for vapor deposition. Vapor deposition is performed using metal balls such as tungsten and molybdenum. The process is carried out using a resistance heating vapor deposition method.

At this time, the mixed solid solution oxide of the raw material is melted in the boat, further subjected to a reduction reaction by the metal boat, evaporated, and deposited on the substrate. The vapor-deposited film obtained in this manner is a thin film exhibiting a pale yellow to yellowish transparent color. The film thickness used is in the range of 300 to 3000A.

The degree of vacuum during vapor deposition was 5 x 10-577 mHg, and even if the vapor deposition conditions were changed, there would be no noticeable difference in the properties of the optical recording medium obtained. However,
The composition of the deposited film that is obtained is different from that of the raw material because the raw material undergoes a reduction reaction and is deposited as in the previous step.
It has a composition in which at least one of Ox3 and InOx4 (0 x X2, !, X4 x 1.5) is added. Recording on the recording medium is performed by irradiation with light such as xenon, flash lamp light, He--Ne laser light, semiconductor laser light, -infrared lamp light, or heating by contact with a heater or the like.

Next, examples of the present invention will be described in detail.

Example 1 Raw materials include TeO2 powder and Tl.

Use O3 powder. 9(TeO2)1-y1(Tl2O
3) Weigh and mix raw materials to the composition of y1 (a) <y1 x 0.3), melt in a platinum crucible for 3 to 5 minutes, and then rapidly cool in air.

A yellow glassy solid solution is obtained. This mixed solid solution is crushed into powder and vapor-deposited using a 7-volume tungsten bow in a vacuum with a degree of vacuum of 5×10 −5 T0 nHg. The thickness of the evaporation substrate is 1
An 80μ polyethylene terephthalate resin film is used. In this case, the film substrate is rotated at a rotation speed of 30 to 360 rpm to obtain a uniform deposited film. The deposition rate is 20 to 40 AIsec. FIG. 1 is a spectral transmittance curve of an optical recording medium having a deposited film with a thickness of 1600 Å obtained at the composition ratio y1=0.1. The part indicated by a in the figure is the initial final recording state, and b is the curve of the recording state by the xenon flash lamp. An optical recording medium having the characteristics shown in FIG. 1 has a transmittance T1 of 40 at a semiconductor laser wavelength of 8200
%, change in transmittance Δ due to writing when reflectance R1 is 5%
T reaches 20%. This recording medium is 80TLJ1C1
Recording can be performed with a semiconductor laser light pulse having an energy density of 1, and information can be reproduced by detecting a change in transmittance without causing any change to the recording medium using a weak power semiconductor laser light. Example 2 TeO2 powder, Tl. O3 powder and Bi2
Use O3 powder.

(TeO5)1-Y2-Y3・ (Tl2O3)Y2・
Raw materials are weighed and mixed in a composition ratio of (Bl2O3)Y3(a)<Y2, Y3<1.5), and a mixed solid solution is prepared in the same manner as in Example 1. The resulting mixed solid solution is a yellowish glassy substance. This mixed solid solution is powdered.
This is used as a raw material for vapor deposition, and vapor deposition is performed using a tungsten boat in a vacuum at a vacuum degree of 5×10 −5 TnmHg. A 2 wt thick polymethyl methacrylate resin disk is used as the deposition substrate. In this case, the substrate is rotated at a rotational speed of 30 to 360 r'Pm in order to form a uniform deposited film. The deposition rate is 20-40 AIsec. Figure 2 shows the film thickness 1 obtained with the composition '2 = 0.1 and Y3 = 0.1.
It is a spectral transmittance curve of an optical recording medium having a 100A vapor deposited film. In the figure, the curve indicated by c indicates the initial recording state, and the curve indicated by d indicates the recording state by the xenon flash lamp. The optical recording medium having the characteristics shown in FIG. 2 has a transmittance T1 of 23% and a reflectance of 6% for semiconductor laser light with a wavelength of 8000A, so the absorption efficiency A1
That is, the ratio of the light amount obtained by subtracting the transmission loss light amount and the reflection loss light amount from the irradiation light amount to the irradiation light amount reaches 71%. In this case, the change in transmittance ΔT due to recording was 11%. This optical recording medium is 40771. Recording can be performed using a semiconductor laser light pulse with a wavelength of 8200A having an energy density of JIC71f, and information can be reproduced by detecting changes in transmittance without changing the recording medium using a semiconductor laser light of about 1WL,W. FIG. 3 is a spectral transmittance curve of an optical recording medium having a deposited film with a thickness of 1100 Å obtained at the above composition ratio of Y2=0.0 and Y3=0.1. In the figure, the curve indicated by e indicates the initial final recording state, and the curve indicated by f indicates the recording state recorded with a xenon flash lamp. The optical recording medium having the characteristics shown in FIG. 3 has a wavelength of 6328A(7)He.
-Ne laser light, when the transmittance T1 is 20% and the reflectance R is 5%, the absorption efficiency A1 as defined above reaches 75%. In this case, the change in transmittance ΔT due to writing is 12%. This optical recording medium can be recorded with a He-Ne laser beam with an energy density of 407 TLJICIt, and information can be reproduced by detecting changes in the transmittance of the recording medium without changing the recording medium using a 20 μW (7) He-Ne laser beam. I can do it. Figure 4 shows the total addition amount y (=Y
2+Y3) and the maximum value of transmittance change ΔT and reflectance change ΔR emitted by semiconductor laser light with wavelength input = 8200A.

Recordings were made with a xenon flash lamp. In the figure, the curve indicated by g indicates the change in transmittance ΔT, and the curve indicated by h indicates the change in reflectance ΔR. From Figure 4, in the range where Y2+Y3 is 0.3 or less, ΔT>10%
, ΔR>8%, indicating that information can be reproduced efficiently.

Example 3 TeO2 powder, Tl2O3 powder, BiO3 powder, and In2O3 powder are used as raw materials.

(TeO2)1-Y4-Y, -Y6('11203),
, .(Bl2O3)Y5.(In2O3)Y, raw materials are weighed and mixed in the composition ratio, and a mixed solid solution is prepared in the same manner as in Example 2. The resulting mixed solid solution is a black glassy material. This was vacuum-deposited using the same method and conditions as in Example 2 to a thickness of 5TnI! A L glass disk coated with polyvinyl alcohol to a thickness of 3 μm is used. In this case, in order to obtain a uniform deposited film, the substrate is rotated at a rotational speed of 30 to 360 r''Pm. The deposition rate is 20 to 40A1sec. Figure 5 shows that for the above composition ratios, Y4 = 0.1, Y5 = 0 .1, Y6=0.
2 is a spectral transmittance curve of an optical recording medium having a vapor deposited film obtained from No. 05.

In the figure, the curve indicated by i indicates the initial final recording state, and the curve indicated by j indicates the recording state by xenon flash. The optical recording medium having the characteristics shown in FIG. 5 has a transmittance T1 of 29% and a reflectance R1 of 26% for semiconductor laser light having a wavelength of 8200A. In this case, the change in transmittance ΔT due to recording is 20%, and the change in reflectance ΔR is 1.
It is 0%. This optical recording medium has an energy density of 507
T! ．． JIC! It is possible to record with a semiconductor laser beam of 1TrL. It is possible to detect changes in transmittance and reflectance of a recording medium and reproduce information using a semiconductor laser beam of about 200 nm without changing the recording medium. The optical recording medium of the present invention using a thin film containing tellurium low oxide as a main component and at least one of thallium low oxide, bismuth low oxide, and indium low oxide as an additive component is different from the conventional tellurium low oxide. It has the following effects compared to an optical recording medium that uses a thin film mainly composed of oxides.

(1) High sensitivity.

5. The absorption efficiency of the thin film for recording laser light is high, and recording can be performed by irradiation with He-Ne laser light or semiconductor laser light with an energy density of 50 m, J1d or less, which was previously impossible.

(2) When reproducing information recorded with θ He-Ne laser light, semiconductor laser light, etc. with high reproduction efficiency, the difference ΔT in transmittance between the initial recording part and the recording part is 20% or more, and the reflectance changes. It is possible to provide an optical recording medium in which the difference ΔR is 10% or more.

[Brief explanation of the drawing]

Figures 1 to 3 are diagrams showing spectral transmittance curves of optical recording media in examples of the present invention, respectively, and Figure 4 shows the amount of additive components added and xenon flash of an optical recording medium in an example of the present invention. A diagram showing changes in transmittance and changes in reflectance upon irradiation, and FIG. 5 is a diagram showing a spectral transmittance curve of another example of the present invention.

Claims (1)

[Claims] 1 In optical recording media that record information by causing a state change using energy such as light or heat and utilizing the change in optical properties, tellurium low oxide TeO_x_1 (
0<x_1<2.0), a low oxide of thallium TlO_x_2 (0<x_2<1.5), a low oxide of bismuth BiO_x_3 (0<x_3<1.5), and a low oxide of indium. InO_x_4(0<x_4<1
．． Addition amount of at least one of 5) y mol% (0<y<
An optical recording medium comprising a thin film containing 30) formed on a substrate.