JPH0318261B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to information recording boards, especially video discs,
This invention relates to a method for manufacturing disks such as PCM audio disks. Photoresists have traditionally been used to manufacture information recording plates. That is, a master disc made of glass or the like with a polished surface is prepared, and this master disc is cleaned and cooled (a process that takes about one hour). This master is coated with a thin layer of photoresist, prebaked, and then cooled (a process that takes about 1 hour). A laser beam or the like modulated by the signal to be recorded is irradiated onto the master disk coated with this photoresist to record the signal (a process of about 1 to 2 hours). This exposed master is developed, washed with water, drained, and then afterbaked and cooled (a process that takes about 1 hour). As a result, a master disc having pits corresponding to the recording signals formed on its surface is obtained. Then, a metal reflective film is coated on the recording surface on which the pits have been formed (a process of about 45 minutes). The master disk coated with the reflective film is played back using an inspection playback machine and inspected for dropouts, etc. (a process that takes about 1 to 2 hours). Only master discs that pass this inspection will be sent to the process of manufacturing stampers for producing large quantities of replicas. However, such conventional methods require about 4 to 5 hours from the start of signal recording to the completion of the test.
It took time, and until that time had passed, it was not possible to distinguish between good and defective products. Therefore, if the product is found to be defective after about 4 to 5 hours, it is necessary to manufacture the information recording plate again from the beginning over the same amount of time, which is extremely inefficient. This is because, since a photoresist is used as a recording film, it is not possible to perform so-called monitoring in which recorded signals are simultaneously reproduced immediately after recording or during signal recording. Furthermore, even if the signal recording itself is accurate, if the developing time etc. are incorrect in the subsequent development process, not only will the product be defective, but the photoresist will also be exposed to natural light. Because of this risk, handling in a bright room becomes difficult, resulting in an extremely low yield. Therefore, the natural manufacturing cost was also high. Taking these drawbacks into consideration, a method of using a material that can be monitored as a recording film is proposed, for example, in US Patent No.
Proposed in No. 4097895. In this method, an aluminum reflective film is formed on a glass master disk, and a recording film made of a dye (fluorescene) that has a remarkable absorption property for a predetermined wavelength is formed thereon. When irradiated with an argon laser, this dye sublimes and forms pits because it has a significant absorbency to the wavelength of the argon laser.
When the recording film on which pits are formed is irradiated with an argon laser that is sufficiently smaller than during recording and has a power that does not sublimate the dye, pits are formed and the laser beam is reflected in the exposed areas of the reflective film, forming pits. Since the laser beam is absorbed and not reflected (or the reflectance is sufficiently small) in the areas where the dye remains, it is possible to determine the presence or absence of pits and reproduce the signal from the difference in light intensity. In the case of this method, monitoring is possible, a wet developing step is not required, and since the material has absorbency only for a predetermined wavelength, it can be handled even in a bright room. However, this method has the disadvantage that the dye sublimation rate is slow, the pits are not well formed, and an information recording plate with sufficient SN cannot be obtained. An improved method of this is, for example, published in Japanese Patent Application Laid-Open No. 55-87595.
It is disclosed in the Institute of Electronics and Communication Engineers technical research report (CPM79-59) ``Real-time laser recording using dye evaporation recording material'' published on November 22, 1979. That is, on a transparent film such as polyester or polyethylene or on a substrate such as acrylic, a dye sensitizer (dye) such as ethyl red, methylene blue, brilliant green, etc. and nitrocellulose (degree of polymerization of about 80) are dissolved in a ketone solvent. The dye sensitizer is coated with a dye sensitizer, and a signal is recorded by irradiating it with a laser beam having a wavelength at which the dye sensitizer has significant absorption. This method uses not only a dye (dye sensitizer) but also nitrocellulose, which has a high sublimation rate due to its self-oxidation effect and allows recording at low temperatures (low power). It has the advantage of being more neatly arranged than in the case of using only the dye mentioned above. However, in this method, compared to the case of using the photoresist described above, not only the shape of the pits is not sufficiently prepared, but also reaction residues are generated and remain as dust-like foreign matter on the recording surface, and sufficient SN cannot be achieved. It was not possible to manufacture an information recording board with This is because the absorption wavelength of conventional dye sensitizers such as ethyl red, methylene blue, and brilliant green does not match the wavelength of the argon laser, resulting in insufficient sublimation. This has been a cause of deterioration of the S/N ratio due to the reaction residue as described above. The present invention was made in view of this situation, and uses N-ethyl-Noxyethylaniline as a dye sensitizer to prevent the generation of foreign matter due to reaction residue, thereby achieving a sufficient S/N.
The purpose of the present invention is to provide an information recording board having the following characteristics. An embodiment of the present invention will be described in detail below with reference to the drawings. In the present invention, first, a substrate 1 is prepared as shown in FIG. The base 1 can be made of, for example, approximately circular glass with a polished surface. Of course, if the information recording plate is used as a master and only one information recording plate is to be obtained, instead of manufacturing a large number of replicas from it, the substrate 1 can be made of synthetic resin such as polyester or acrylic. Foundation 1
is cleaned and then cooled, and then a reflective film 2 made of, for example, silver or aluminum is vapor deposited on its surface and coated to a predetermined thickness (for example, 200 Å) by sputtering or the like.
400 Å). If this thickness is too thin, a sufficient amount of reflected light cannot be obtained for monitoring, and if it is too thick, there will be no functional problem, but material will be wasted. about silver
When the reflective film 2 is formed with a thickness of 200 Å, the reflectance for the helium neon laser for readout is
It was 80 to 85%. On the reflective film 2, there is further an information recording layer 3 containing a dye sensitizer and nitrocellulose.
form. α as a raw material for nitrocellulose
Cotton linters with a cellulose content of 97% or more are best. If the content of α-cellulose is low, reaction residues will be scattered on the recording surface, making it impossible to obtain a sufficient SN. Therefore, in order to obtain an information recording plate that can be put to practical use, it is preferable to use a material containing 97% or more of α-cellulose. The number average degree of polymerization of nitrocellulose is suitably 80 to 95 (corresponding to RS1/2 in JIS). If the degree of polymerization is smaller than this, the shape of the pits will not be neatly arranged, and if the degree of polymerization is larger than this, the viscosity will be too strong, making it difficult to coat the recording layer 3 evenly to a predetermined thickness. This cotton linter is nitrified by the sulfur/nitrogen mixing method or other methods, and the degree of nitrification is at least 13%, preferably,
It is good if it is 13.32% or more. If the degree of nitrification is insufficient, pits cannot be formed unless the power of the recording beam is increased, and if the power is increased too much, the shape of the pits will be distorted. Therefore, as will be described later, it is better to increase the degree of nitrification to some extent and record with relatively low power. The nitrocellulose thus obtained is dissolved in an organic solvent (for example, xylene or a mixture of xylene and ethyl cellosolve acetate) and filtered twice using, for example, a 0.2 μm filter. N-ethyl-Noxyethylaniline is used as the dye sensitizer, and is dissolved in an organic solvent and filtered in the same manner as described above. Thereafter, the organic solvent in which nitrocellulose was dissolved and the organic solvent in which the dye sensitizer was dissolved were mixed so that the nitrocellulose and dye sensitizer had a predetermined weight fraction, and then the nitrocellulose and dye sensitizer were mixed. An organic solvent is added at a ratio of, for example, 46 c.c. to 1 g of the mixture with the sensitizing agent, heated to 40° C., and shaken for about 4 hours. This liquid is again subjected to the filtration process and used as a material for the information recording layer 3. When making this material, when the weight fraction of nitrocellulose and dye sensitizer is changed, the light transmittance changes as shown in FIG. 2. In the figure, A is the case where the weight fraction is 95.0 to 5.0, B is 90.0 to 10.0, C is 86.5 to 13.5, and D is 80
This is a case of 20 vs. In both cases the wavelength is 440nm
It has remarkable light absorption in the range from 530 nm to 530 nm, and the degree of absorption becomes more remarkable as the content of the dye sensitizer increases. For example, as shown in C, the weight fraction
When the ratio is 86.5 to 13.5, the kinematic viscosity at 25℃ is
3.6 cst, which is about 35% transmittance (and therefore about 65% absorption) for argon laser whose wavelength is 456.1 nm. This material is spin-coated onto the reflective film 2 to form the information recording layer 3. For example, by dropping 10 c.c. of the material onto the reflective film 2, rotating it at 250 rpm for 11 seconds, and further rotating at 600 rpm for 61 seconds, it is possible to form the information recording layer 3 with a thickness of about 2500 Å. When performing spin coating, the information recording layer 3 can be formed uniformly and evenly by rotating the substrate 1 on which the reflective film 2 is formed first at a low speed and then at a higher speed. After forming the information recording layer 3, heat at approximately 80°C for 15 minutes to 20 minutes.
Bake for a minute to evaporate the organic solvent and then cool. If any organic solvent remains, extra power will be required to evaporate it during signal recording, and if the power during recording is insufficient, the pits will not be formed sufficiently and the reaction will be delayed. It also causes residue to appear. Also, with some dye sensitizers, when the organic solvent is evaporated and dried, they become non-uniform and become uneven, but this does not occur with N-ethyl-Noxyethylaniline. . After forming the information recording layer 3 in this manner, a so-called mastering process for recording signals is performed. For example, the master disk on which the information recording layer 3 has been formed is heated at a linear velocity of 1.25 m/
For example, an argon laser with a wavelength of 456.1 nm is rotated by
Fourteen Modulation) is modulated and irradiated onto the information recording layer 3 from the information recording layer 3 side. Then, the dye sensitizer in the area irradiated with the laser beam sublimes due to the heat, since the dye sensitizer has a significant absorption property for the wavelength of the argon laser. Further, since nitrocellulose is mixed, the nitrocellulose also sublimates due to its self-oxidation effect, while the sublimation of the dye sensitizer is also promoted, forming pits 4 as shown in FIG. The portion 5 that is not irradiated with the argon laser remains as it is. This sublimation phenomenon does not occur unless the dye sensitizer is irradiated with light in a wavelength band in which it exhibits significant absorption at a level above a predetermined threshold, so not only the mastering process but also the storage and handling of the master disc can be done in a bright room. The reading power on the information recording layer 3 of the master disc itself on which signals are recorded in this way is approximately
When it was applied to a regenerator using a helium-neon laser with a power of 0.3 mW and a wavelength of 632.8 nm, regeneration was possible. The reproduction principle is not clear, but since the dye sensitizer used has almost no absorption for the wavelength of the helium-neon laser, the amount of reflected light increases at least at pit 4.
It is not based on the principle that the remaining portion 5 absorbs the light and reduces the amount of reflected light (of course, if an argon laser is used for reading, reproduction based on this principle is possible). This is probably because diffraction or interference occurs in the pits 4 and the amount of reflected light decreases, while in the remaining portions 5 the amount of reflected light increases due to the reflective film 2. In any case, it is practically important that reproduction is possible with a helium-neon laser. In the case of bare argon lasers, cooling devices are required and are very large-scale, making them difficult to use in consumer regenerators, but helium neon lasers can be fully used in consumer regenerators (there are currently no commercially available lasers). This is because there are This means that the information recording plate of the present invention can be reproduced even by using a semiconductor laser with a longer wavelength. The weight fraction of nitrocellulose and dye sensitizer is
In the case of 86.5 vs. 13.5, the master disk recorded by changing the recording power on the information recording layer 3 is played back as it is with a playback machine using a helium neon laser, and the level of the playback RF signal, the position of the eye pattern,
When we examined changes in the average error rate per 30 seconds (average for about 10 to 50 minutes), we found the following table.

【table】

[Table] On the other hand, if you develop the photoresist to form pits and then play back the original with a metal reflective film coated on the entire surface of the photoresist, the RF level will be
1000 to 1300mVpp, eye pattern in the center or slightly below center, error rate in the 10s. That is, in the information recording plate according to the present invention, if the recording power is selected appropriately (2.8 to 3.0 mW), the error rate can be improved by one order of magnitude compared to when a conventional photoresist is used. This means that the signal is recorded more accurately. Furthermore, even if played immediately after mastering, a reproduced RF signal level of 460mW to 550mW can be obtained, and since the eye pattern is located slightly below the center, it is easy to read out the signal, and it is not only possible to monitor, but also to form pits. Sometimes reaction residues come out and the information recording layer 3
Since it has never been found to be scattered on the surface, it can be used as is as a single information recording board with a practically sufficient SN. Further, a metal such as silver is coated as a conductive layer on the information recording layer 3 by vapor deposition, sputtering, electroless plating, etc., and then a release agent is coated on top of the conductive layer, and then a metal such as nickel is coated by electroforming or the like. , a metal such as nickel can be peeled off from the master and used as a stamper. (Of course, you can use this metal disc as a master disc, obtain a mother disc, and then make a submaster disc and use this as a stamper.) Replicas that are mass-produced based on stampers can be made by selecting the material appropriately. , an optical type, a capacitance type, a piezoelectric type, etc., and the information recording plate can be read out by a pick-up. Furthermore, the master disk according to the present invention is monitored during mastering or immediately after mastering is completed, and if it is found that the master has failed, the mastering is immediately stopped, and the recording layer 3 can be easily removed by pouring an organic solvent on the recording layer 3. After shaking off the organic solvent, a new recording layer 3 can be immediately formed on the master disc. In the case of photoresist, if you do not cover the photoresist after polishing the base surface again, the base surface will become rough.
Considering that the SN becomes worse, this means that the information recording plate of the present invention is more practical. As the organic solvent in this case, xylene may be used, but since it is preferable that the drying rate is faster in such applications, for example, acetone may be used. Furthermore, in the present invention, if a monitor is not required, it goes without saying that the recording layer 3 may be formed directly on the substrate 1. In addition, the information to be recorded in the present invention is
It is not limited to audio signals, video signals, etc., and the information recording board is a video disk,
It can be applied to things other than PCM audio disks, etc. As described above, the invention of the present application forms an information recording layer containing nitrocellulose and a dye sensitizer on a substrate, and irradiates the information recording layer with light of a wavelength at which the dye sensitizer exhibits remarkable absorption characteristics. In information recording plates that record information by irradiation, N is used as the dye sensitizer.
By using -ethyl-Noxyethylaniline, the sublimation rate is sufficiently fast compared to conventional dye sensitizers, there is no reaction residue, and sufficient S/
It has become possible to obtain a monitorable information recording board.

[Brief explanation of the drawing]

The figures are all related to the present invention; FIG. 1 is a cross-sectional view of an information recording plate, and FIG. 2 is a graph showing changes in transmittance with respect to wavelength. DESCRIPTION OF SYMBOLS 1...Base, 2...Reflection film, 3...Information recording layer, 4...Pits, 5...Remaining part.

Claims (1)

[Claims] 1. α-cellulose having a predetermined number average degree of polymerization
Nitrocellulose is obtained by nitrifying a material containing 97% or more to a predetermined degree, and the nitrocellulose and a dye sensitizer are dissolved in an organic solvent at a predetermined weight fraction,
The organic solvent in which the nitrocellulose and the dye sensitizer are dissolved is filtered, and the filtered organic solvent is spin-coated on a substantially circular substrate as an information recording layer,
A laser beam having a wavelength at which the dye sensitizer exhibits significant absorption is modulated by a recording information signal, and the modulated laser beam is irradiated onto the information recording layer to form pits, the method comprising: A method for manufacturing a disk, characterized in that the dye sensitizer is N-ethyl-Noxyethylaniline. 2. A method for manufacturing a disk according to claim 1, characterized in that a reflective film that reflects the laser beam is formed on the substrate, and the information recording layer is formed on the reflective film. . 3. The above-mentioned claim 1, wherein the nitrocellulose and the dye sensitizer are each dissolved separately in the same organic solvent, and then mixed to a predetermined weight fraction. 1st term or 2nd term
2. Method for manufacturing the disk described in Section 1. 4. The method for manufacturing a disk according to claim 3, wherein the organic solvent in which the nitrocellulose and the dye sensitizer are dissolved separately is filtered before being mixed. 5. Claim 1, wherein the degree of nitrification of the nitrocellulose is 13% or more.
4. The method for manufacturing a disk according to item 2, item 3, or item 4. 6 The number average degree of polymerization of the above α-cellulose is 80 to 95.
The first claim characterized in that
The method for manufacturing a disk according to item 1, item 2, item 3, item 4, or item 5. 7. Claims 1, 2, and 3, wherein the organic solvent is xylene or xylene and ethyl cellosolve acetate.
The method for manufacturing a disk according to item 4, 5, or 6. 8 α cellulose having a predetermined number average degree of polymerization
Nitrocellulose is obtained by nitrifying a material containing 97% or more to a predetermined degree, and the nitrocellulose and a dye sensitizer are dissolved in an organic solvent at a predetermined weight fraction,
pass through the organic solvent in which the nitrocellulose and the dye sensitizer are dissolved, form a reflective film on a substantially circular glass substrate, spin coat the passed organic solvent onto the reflective film, A laser beam having a wavelength at which the dye sensitizer exhibits remarkable absorption characteristics is modulated according to the recording information signal, and the modulated laser beam is irradiated onto the information recording layer to form a pit, thereby forming the pit. A conductor layer is formed on the information recording layer, a metal film such as nickel is formed on the conductor layer, and the metal film is peeled off to transfer the recorded information formed on the metal film to another member. It is a thing,
A method for manufacturing a disk, characterized in that the dye sensitizer is N-ethyl-Noxyethylaniline.