JPS63146247A - Optical information recording method and its optical information recording medium - Google Patents

Abstract

PURPOSE:To accurately write or read information with use of a comparatively inexpensive device by having a preliminary process where the projecting bits are formed previously at periodical positions and then a recording process where the prescribed one of these bits is erased or deteriorated by heat to provide the information volume to the positions of remaining bits of the project ed bits. CONSTITUTION:The projecting bits 20 are formed previously at the periodical positions in a preliminary process. Then the prescribed one of those bits 20 is erased or deteriorated by heat in a recording process. While the information value is provided to the positions of remaining bits 20. Thus the remaining bits 20 have prescribed sizes and shapes decided by the conditions of said prelimi nary process regardless of the conditions of said recording process using heat. Here no highly accurate control is required to the heat value needed for erasion or deterioration of the bit 20. Thus it is possible to secure a stable size and shape of an information bit despite deterioration of accuracy of a writing device. Then an accurate reading action is ensured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical information recording method and an optical information recording medium used therein.

[Conventional technology]

In recent years, optical information recording methods that can perform high-density information recording have become widespread, and optical disks, optical cards, and the like are currently being actively used as optical information recording media used in this method. Such optical information recording methods generally employ write-once recording methods. That is,
A thermally destructible metal thin film or organic material thin film is uniformly formed on the entire surface of the recording substrate, and this thin film is partially thermally destroyed to form concave minute bits. The information bit “01” depends on the presence or absence of
”.To form microbits, a focused laser beam or an electric heating element (thermal recording head) is used.

[Problem that the invention seeks to solve]

As mentioned above, conventional optical information recording methods write information by forming minute pits on a thin film using heat, but in order to read the information recorded in this way with high accuracy, It is necessary to keep the size and shape of the micro pits constant. If there are variations in the size of tiny bits, the read signal level will fluctuate, and if there are variations in the shape, the noise level on the read signal will increase.
In either case, accurate reading becomes impossible and becomes a factor that reduces the reliability of reading. For this reason, conventionally, expensive devices that can write and read information with high precision have been required.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an optical information recording method that allows accurate writing and reading of information using a relatively inexpensive device, and an optical information recording medium used in the method.

[Means for Solving the Problems] The present invention provides an optical information recording method in which optically readable information bits are formed on an information recording medium by heat. An optical information recording medium is prepared in which a plurality of convex bits made of a material with a different reflectance or transmittance from that of the recording substrate is formed, and information to be recorded is selected from among these convex bits. Information is recorded by erasing or changing the quality of the convex bits selected based on the heat, thereby making it possible to accurately write and read information using a relatively inexpensive device.

[For production]

In conventional optical information recording methods, concave bits are formed on a recording medium, and the amount of information is provided at the position where the concave bits are formed. In contrast, in the method according to the present invention, a preliminary step is performed in advance in which convex bits are formed at periodic positions, and then a recording step is performed in which predetermined ones of the convex bits are erased or altered by heat. The amount of information is given to the remaining position of the convex bit. Therefore, regardless of the conditions of the thermal recording step, the remaining convex bits will always have a predetermined size and shape determined by the conditions of the preliminary step. The amount of heat applied to erase or alter the convex bits does not need to be controlled with high precision. That is,
It is sufficient to control the amount of heat to a value that is greater than or equal to a value sufficient to erase or alter one target convex bit, and does not exceed an amount of heat that is large enough to affect adjacent convex bits. Therefore, even if the accuracy of the writing device is reduced compared to the conventional method, the size and shape of the information bits can be stabilized and accurate reading becomes possible. That is, according to the present invention, it is possible to write and read information using a relatively inexpensive device.

〔Example〕

The present invention will be described below based on illustrated embodiments. FIG. 1 is a partial perspective view of an optical information recording medium according to an embodiment of the present invention. This optical information recording medium is composed of a recording substrate 10 and a plurality of convex bits 20. As shown in the cross section of FIG. 1, the recording substrate 10 further includes a base member 11 and a surface member 12. The base member 11 serves as the foundation of this optical information recording medium, and in this embodiment, a 0.2 mm thick polyester plate is used. Moreover, the surface member 12 has a thickness of 1 to 2
Consists of a thermosetting black ink layer of μm. Convex bit 2
In this example, 0 is a circular Te metal thin film with a thickness of 500 to 5000 A and a diameter of 40 μm, and the recording substrate 1
0 at predetermined periodic positions (1/300 inch pitch).

This optical information recording medium was manufactured as follows. First, thermosetting black ink is applied onto the polyester plate (base member 11) and cured by heat.
A surface member 12 is formed.

Subsequently, Te metal is deposited on the surface member 12 to form a Te metal thin film on the entire surface. Then, a photoresist (for example, Az-based positive resist manufactured by Silaplay Co., Ltd.) is coated and dried on this metal thin film, and a pattern film having a circular pattern is closely attached to this photoresist and exposed, and then developed to remove the circular portion. Only leave the resist.

Next, using this remaining resist as a mask, the Te is etched away using a weak alkaline solution (thus, an optical information recording medium having the structure shown in FIG. 1 is obtained. The black ink is light absorbing, Since Te metal is light reflective, the recording substrate 10 and the convex bit have different reflectances.

Now, in order to record information on such an optical information recording medium, the following writing process was performed.

That is, a semiconductor laser beam was focused on a predetermined convex bit 20 and irradiated multiple times, and the convex bit 20 was evaporated and erased by heat. If multiple beams are used,
It is also possible to perform evaporation erasure with one irradiation. Based on the information to be recorded here, the convex bit 2o to be erased
If you select, for example, a writing result as shown in FIG. 2 can be obtained. Two states are obtained: a case in which the convex bit 20 remains at a circumferential position and a case in which it has been erased. If these two states correspond to logic "0" and "1°" and are used as information bits, arbitrary information can be recorded.Other recording methods include argon laser with an output of 100 mW and xenon laser with an output of 250 W. The convex bit 20 may be erased with one focused irradiation using a powerful light source with a large diameter such as a lamp or a high-output infrared lamp.Alternatively, the convex bit 20 may be erased using an electric heating element. For example, the convex bit 20 may be destroyed by applying an energy of about 1 mJ to a commercially available electric thermal head.

Generally, a method of erasing using light is suitable for relatively high-density recording, and a method of erasing using an electric heating element is suitable for relatively low-density recording.

The advantage of the above erasing process is that it is relatively easy to control the energy and position of the heat source used for erasing. That is, the energy of the heat source is transferred to one convex bit 20.
If it is large enough to erase
It does not matter if there is some variation, and it does not matter if some error occurs in the relative position between the heat source and the convex bit 20. However, the energy and positional errors must not be so large as to affect adjacent convex bits 20. As long as this condition is satisfied, information bits as shown in FIG. 2 can be recorded accurately. Therefore, as the writing device, an inexpensive device with relatively large tolerances for energy control and position control can be used. In FIG. 2, the size and shape of the remaining convex bit 20 are always constant regardless of the accuracy of this writing device, and accurate reading can be performed. Although the convex bit 20 has a circular shape when viewed from above in the above-described embodiment, it can also have a shape such as an ellipse, a square, a rectangle, or a rhombus.

Note that in order to protect the convex bit 20 from external environments such as friction, the structure shown in FIG.
It is preferable to form a transparent protective layer on the upper surface of the 0 and convex bits 20. When the subsequent recording process is performed using light, the thickness of this protective layer can be approximately 0.3 to 2 mm, but when it is performed using an electric heating element, it is several microns thick.
It is preferable to set it as about m - 100 micrometers. As the material for this protective layer, resin materials such as polycarbonate, polyester, acrylic resin, and polystyrene resin, which are used in optical discs, can be used, and these resins can be applied or bonded in the form of a film. The protective layer can be formed by

In the above-described embodiment, a black ink layer was used as the surface member 12 of the recording substrate 10, and a Te metal thin film was used as the convex bit 20, but in the present invention, the recording substrate 10 and the convex bit 20 are different. Any material may be used as long as it has reflectance. However, in order to improve the reading accuracy, the recording substrate 10 and the convex bit 20 must be
It is better to have a large contrast between the convex bits 20 and the convex bits. When a light-absorbing material is used as the recording substrate 20, it is preferable that the surface of the recording substrate 10 is a light-reflecting material such as a natural material or a metallic luster material. The light-reflective convex bits include Mn, Zn, Al, In, and S.
n, Bi.

Metal materials with relatively low melting points such as Te and Pb or alloys thereof can be used. As the light-absorbing convex bit, MnS, Cu2S, As25 Sb2S3.
Colored sulfides such as Bi253, oxides such as 3'' Cub, PbO, InO, etc. can be used.In addition, thin films of organic colorants (including black and white) have a lower coloring property than metals and other compounds. It has the advantage that the hue can be freely selected and there are a large amount of compounds with various melting points, so it can be fully used as a convex bit.

Furthermore, since these organic materials can be easily made into paints or inks, they have the advantage that convex bits can be formed using a coating method or a printing method. Note that the surface member 12 needs to be stable against heat and other external environments, but there are many paints and inks that meet these conditions, and they can be easily selected from general commercially available products. I can do it.

In the above embodiments, an optical information recording medium that performs reflective reading is described, but the present invention can also be applied to an optical information recording medium that performs transmissive reading. In this case, materials having different transmittances may be used for the recording substrate 10 and the convex bit 20, respectively. Furthermore, the recording of information is
In addition to the method of erasing the convex bits 20, a method of thermally changing the convex bits 20 into a material whose reflectance or transmittance is approximately equal to that of the recording substrate 10 may be used. Therefore, as the convex bit 20, it is possible to use not only a material that is destructive and evaporative with respect to heat, but also a material that has alteration properties.

Transmittance means reflectance with respect to the wavelength of the reading light.

This refers to transmittance, and when selecting each material, the reading light wavelength must be considered.

〔Effect of the invention〕

As described above, in the optical information recording method according to the present invention,
A preliminary step is performed in advance in which convex bits are formed at periodic positions, and then a recording step is performed in which predetermined convex bits are erased or altered by heat, and an amount of information is recorded at the remaining positions of the convex bits. This makes it possible to stabilize the size and shape of the information bits even if the accuracy of the writing device is reduced compared to conventional methods, making accurate reading possible and allowing information to be read using relatively inexpensive equipment. can be written and read.

[Brief explanation of the drawing]

FIG. 1 is a partial perspective view of an embodiment of an optical information recording medium according to the present invention, and FIG. 2 shows a state in which the optical information recording medium shown in FIG. 1 is recorded by a method according to an embodiment of the present invention. FIG. 2 is a partial perspective view of a recording medium. DESCRIPTION OF SYMBOLS 10... Recording board, 11... Base member, 12.
...Surface member, 20... Convex bit. Applicant's agent Yuchi Sato 1 Figure 2 Figure 2

Claims (1)

[Claims] 1. An optical information recording method for forming optically readable information bits on an information recording medium by heat, comprising:
a preliminary step of forming a plurality of convex bits made of a material having a different reflectance or transmittance from that of the information recording medium at predetermined periodic positions on the information recording medium; 1. An optical information recording method comprising the step of erasing or deteriorating convex bits selected based on information to be recorded using heat. 2. The optical information recording method according to claim 1, wherein the convex bits are erased or altered by focusing strong light on the convex bits. 3. The optical information recording method according to claim 2, wherein the energy of the focused light is greater than the energy required to erase or alter one convex bit. 4. The optical information recording method according to claim 1, wherein the heating element is located near the convex bit to erase or alter the convex bit. 5. The optical information recording method according to claim 4, wherein the heating energy of the heating element is greater than the energy required to erase or alter one convex bit. 6. An optical information recording medium for forming optically readable information bits by heat, the recording substrate having a reflectance or a transmittance at predetermined periodic positions on the recording substrate. 1. An optical information recording medium comprising a plurality of convex bits made of materials with different ratios. 7. The optical device according to claim 6, wherein a cross section of the convex bit taken along a plane parallel to the recording substrate is circular, elliptical, square, rectangular, or rhombic. Information recording medium. 8. The optical information recording medium according to claim 6 or 7, wherein the convex bit is made of a material that is destructive, vaporizable, or alterable with respect to heat. 9. The optical information recording medium according to claim 8, wherein the convex bit is made of a low melting point metal or a metal compound. 10. The optical information recording medium according to any one of claims 6 to 9, characterized in that a transparent protective layer is formed on the surface of the convex bit.