KR100257896B1 - Optical recording medium - Google Patents

Abstract

PURPOSE: An optical recording media is provided to transfer a charge by a light. Therefore, sensitivity, elimination and stability of the optical recording media can be improved. CONSTITUTION: A reflect layer(2), a charge generating layer(3) and a charge transferring layer(4) are successively deposited on a substrate(1). An overall length discolor element(5) and a protection layer(8) are deposited on an upper terminal of the charge transferring layer(4). The charge transferring layer(4) transfers a charge generated from the charge generating layer(3) by checking a laser beam. Colors of the overall length discolor element(3) are discolored.

Description

Optical recording media

1 is a temporary structural diagram of an optical recording medium of the present invention.

2 is a configuration diagram of a recording state of the optical recording medium of the present invention.

3 is a configuration diagram of an erased state of the optical recording medium of the present invention.

* Explanation of symbols for main parts of the drawings

1 substrate 2 reflective layer

3: charge generation layer 4: charge transport layer

5: full-color discoloration element 6: spacer

7: air layer 8: protective layer

The present invention relates to an organic optical recording medium capable of recording, reproducing and erasing using a laser. This medium is a high-density large-capacity information recording material and can be used as various information recording media or image recording media.

The explosive increase of various types of information due to the high level of information in society requires a high density, high capacity, and high speed of storage media.

Recently, the most practical storage method is a magnetic method in which information is recorded according to the magnetization direction of the magnetic medium. Examples of the use thereof include video tapes, audio tapes, floppy disks, and the like.

However, as the amount of information increased due to social development, a large amount of recording media was required, and thus a magneto-optical recording media appeared. Unlike magnetic materials used in magnetic recording media, the magnetization direction is perpendicular to the surface of the recording film, and the coercivity to maintain the magnetization direction is 5 to 10 times higher than that of the magnetic media. it's difficult. In order to change the magnetic direction, it is possible to record information according to the magnetic direction by changing the magnetic direction to an external magnetic field in a state in which light is connected to 1 µm or less using a laser and heated above the curing temperature. When recording in this way, the information recording unit can be made smaller than 1 占 퐉, so that the recording density can be 10 to 1000 times higher than that of the magnetic memory method.

However, this method uses a heavy metal magnetic material and requires a vacuum deposition or sputtering device in the manufacturing process, there are a lot of manufacturing difficulties. Attempts have been made to use organic optical recording materials to address these shortcomings.

The organic optical recording material can be classified into a write once read many (WORM) type that can only be read after writing once and a rewritable (RW) type that can be erased after writing, depending on whether it can be erased.

WORM type, as mentioned in Japanese Unexamined Patent Publication No. 57-46362, 58-197088, 59-5096, 63-179792, etc., after coating a recording layer by mixing a pigment capable of absorbing a laser with a polymer resin It is made by coating a protective layer thereon. At the time of recording, if the laser is focused on the recording layer within 1 탆 wavelength, the polymer resin, which generates heat by the dye absorbing the laser, is decomposed to form a pit, thereby enabling recording. In recording and playback, the information is read by the difference in reflectance between the portion with and without the pit. In the WORM type, since the recorded portion becomes the decomposition form of the polymer, it is impossible to rewrite after erasing the recording.

The RW type has been actively studied as a thermal method using light as heat and a photon method using photons of light, respectively. In the thermal method, the recording light is irradiated onto the recording layer to locally melt, evaporate, thermally deform or heat transfer, and to record and reproduce by optical changes occurring at that time. Optical recording media using this method, such as CdFe, TbFe, TbFeCo, etc., using the Faraday effect, the cart effect magneto-optical recording medium and Te-based TeOX, Te-Ge, Te-Ge-Sb, Te-Ge- Inorganic systems using Sb-Tl and the like have been actively studied. However, the optical recording medium not only uses materials harmful to the human body, but also has a disadvantage in that the stability of the medium is low and the manufacturing process is difficult because of sputtering of metal compounds. Also in the characteristics of the medium, the recording sensitivity is low, and the stability of the recording state and the orbital property at the time of fast erasing are not satisfied. Therefore, as a harmless, low-cost medium, recording media capable of reliability, high speed, and high sensitivity have been provided. As a material for solving such a problem, a non-toxic and low-cost organic polymer material has been proposed. In such an organic system, a method using a thermoplastic resin and a near infrared absorbing dye (Japanese Patent Laid-Open No. 5848245) and a method using a polyma blend (US Patent 4722595) have been proposed. However, this method also suffers from record sensitivity and record / erase repeatability. In addition, a method using a phase shift of a liquid crystal (Japanese Patent Laid-Open No. 59-10930, 60-114823, 63-74135, U.S. Patent No. 4,855-976, etc.) is known. There is a problem with responsiveness and reliability. In order to improve the manufacturability and reliability of low molecular liquid crystals, U.S. Patent Nos. 4,293,435 and the like have been proposed to use polymer liquid crystals, but there is a problem in recording sensitivity, contrast, repeatability, and responsiveness. In order to improve such responsiveness, a photoisomerization method (Japanese Patent Laid-Open No. 62-109245) has been proposed, wherein photochromic molecules are bound or mixed with the side chains of liquid crystalline polymers forming a photochromic liquid crystal layer, and photochromic molecules The optical isomerization is performed to make the optical recording. However, this also has problems in contrast, repeatability, and preservation and is not used industrially due to the use of short wavelength light source. On the other hand, the optical recording method of the photon method is attracting attention as a high-sensitivity, high-speed optical recording medium, and is known as spiropyran (Japanese Patent Application No. 60-208390), Polgid (Japanese Patent Application No. 63-273688), and polydiacetylene (Japanese Patent Application No. 63-163341). And photochromic materials have been proposed as optical recording media. However, while having the above excellent properties, the light resistance by light is poor, there is a point that the stability of the color development and repeatability is poor. In general, in the case of the photochromic compound, when the recording light is ultraviolet light, the erasure light is visible light, so that it is difficult to stably preserve the recording and to easily cause a reverse reaction during the photochromic reaction.

For these reasons, development has not progressed rapidly while having the advantages of high density and high speed.

In view of the above, a compatible organic recording medium needs to be complemented in terms of stability, sensitivity, and complexity of the erasing system, and a new medium that takes this aspect into consideration in order to switch to a new optical recording method is required.

Accordingly, the present invention aims to construct an optical recording medium having excellent sensitivity, repeatability, erasure, and stability through the transfer of electric charges by moving away from the conventional optical recording method using heat and photons caused by light. .

That is, the present invention relates to a slow exchangeable organic optical recording medium, and performs optical recording by using a procedure different from that of a conventional optical recording. The present invention relates to stability, recording and The present invention provides a novel recording medium having advantages in terms of erasing time, manufacturing process, sensitivity, and the like, particularly excellent in recording sensitivity and stability among recording characteristics.

In more detail, the present invention is an organic optical recording medium in which a substrate, a reflective layer, a charge generating layer, a charge transport layer, and a full-color discoloration element are stacked and a protective layer is stacked on top thereof, and a spacer is formed on top of the full-color discoloration element as necessary. You can also configure the air layer. At this time, the recording method irradiates the surface to be recorded with the collected laser light, and the charge generating material of the charge generating layer is absorbed in the irradiated laser wavelength band to generate charges on the surface, and the generated charges are transferred to the electric field discoloring element ( Electric field effect of the surface formed on the light irradiation site by transporting to the surface of the full-color luminescent device), and the optical recording is performed by causing the color of the full-color chromic device layer to be different from the color of the other part by the influence of the electric charge. It relates to an optical recording medium.

The structure of the optical recording medium of the present invention is, as shown in FIG. 1, the substrate 1, the reflective layer 2, the charge generating layer 3, the charge transport layer 4, the electrochromic device 5, the spacer 6 ), The air layer 7, the protective layer 8, and sometimes the spacer 6 and the air layer 7 may not be formed. According to this configuration, during recording, first, the focused laser light is irradiated on the surface to be recorded so that the charge generating material of the charge generating layer 3 is absorbed in the irradiated laser wavelength band to generate charges on the surface of the charge generating layer. By transporting to the surface of the full-color discoloration element 5 by the charge transport layer 4, the electric field effect of the surface formed at the light irradiation site is generated (FIG. 2). Due to the influence of the electric charge, the electric charge is present in the light irradiation part, so that the color of the full-color discoloration device layer is different from the other part. The recording is made by this characteristic, and the difference in the amount of reflection or transmission in the recorded state is investigated when the record is read by irradiating a weaker intensity than the recording time, that is, the laser intensity below the energy to generate the charge in the charge generating layer 3. Reading is possible by using. In the erasing, the charges on the recording surface are discharged to remove the charges formed on the surface, which makes the erasing much simpler than the conventional organic light recording erasing system (FIG. 3).

In the present invention, the charge generating layer 3 and the charge transport layer 4 may use an inorganic material, and in this case, only one layer may be used. This is because inorganic materials generally have characteristics of charge generation and charge transport. Examples of inorganic materials that can be used include selenium, cadmium sulfide, zinc oxide, and amorphous silicon.

On the other hand, when these layers are made of an organic material, the charge generating layer 3 is coated by dispersing the charge generating material in a resin. The resin used here is a material which can transmit more than 80% of light in the recording wavelength band. Polycarbonate, polymethyl methacrylate, polystyrene, amorphous polyolefin, etc., but polycarbonate resin is generally used. The organic materials as charge generating materials dispersed in the resin are polyazo, perylene tetracarboxy diimide, poly At least one or more of cyclic quinone series, phthalocyanine series, squiarylium series, cypyryllium series and the like can be dispersed and used in the resin. On the other hand, the charge transport layer 4 is a phthalocyanine-based, hydrazone-based, pyrazoline-based, stilbenes-based, triphenylmethane-based, heterocycle-based, conjugate arylamide-based, etc. It may be used by coating at least one dispersion. At this time, the thickness of the charge generating layer 3 is appropriately 0.1 ~ 0.3㎛, the charge transport layer 4 is suitable 3 ~ 30㎛, more preferably 10 ~ 30㎛. The material selection of the charge generating layer 3 and the charge transport layer 4 should be appropriately selected according to the wavelength band of the laser to be recorded.

In the present invention, the full-color discoloration element 5 is a material capable of transmitting 70% or more of light in order to exhibit high reflectance of the recording material, and includes all materials of conductive polymers discolored by electric fields. Compounds of VII are preferred, of which polypyrrole of general formula III is most preferred.

(Wherein n is an integer of 4 or more; R ₁ to R ₉ are hydrogen, an alkyl group, an alkoxy group or a phenyl group; X ⁻ is ClO ₄ −, BF ₄ −, AsF ₅ −).

In case of using these materials, the thickness should be less than 20㎛ by electropolymerization. In this case, if the content of material is too small, the discoloration by electric field is too low. It will not reach the reflectance to be formed, so 0.2 to 20% by weight is suitable for the solvent.

According to such a full-color discoloration device, for example, when polypyrrole is used, it can be easily seen that the color is changed to blue in the oxidized state and yellowish green in the reduced state.

In the present invention, the spacer layer 5 may be provided on both sides of the full-color discoloration element 5 to hold the air layer 7. In this case, the protective layer 8 is finally formed thereon. Preferred spacer 6 materials include glass beads, and the protective layer 8 is preferably the same material as the substrate 1, preferably polycarbonate. In the present invention, the reflective layer 2 is preferably formed by depositing gold or aluminum at 50 to 1000 Pa as a metal component.

In the present invention, in order to maintain a stable state of charge, by placing a photomask on the full-color discoloration element (5), a more stable recording state can be maintained, wherein the photomask should be divided by the focal size of the laser to be recorded and is 3 탆. Hereinafter, about 1 to 3 micrometers are more preferable.

The recording and erasing procedures of the optical recording medium according to the present invention are as described above, but are shown in schematic principles in FIGS. 2 and 3, respectively. Such an organic optical recording medium provided in accordance with the present invention significantly improves recording sensitivity and stability.

An Example is given to the following and this invention is further demonstrated to it.

Example 1

After depositing 800 Å of gold (Au) on the polycarbonate substrate, dissolve the phthalocyanine-based product name Progen (manufactured by ICI) as a charge generating material therein with a polycarbonate resin in a weight ratio of 50:50 in a solvent and spin-coating to 0.2㎛ 80 Stored at 10 ℃ for 10 hours to dry the solvent. The charge transport material on the charge generating layer was dissolved in a solvent at a weight ratio of 50:50 with polycarbonate and dried under the same conditions. At this time, a brand name protranti (ICH Co., Ltd .: Hydronic system) was used as a charge transport material. The polypyrrole of the general formula (III) electrolytically polymerized as a full-length discoloration element (5) was dissolved at 5% by weight relative to the solvent, spin-coated to a thickness of 5 µm, and heated at 80 ° C. in an oven for 5 hours to dry the solvent sufficiently. Let's do it. At this time, the specific molecular formula of the polypyrrole used as the recording layer material is shown in Table 1 below (III-1). The spacer material (glass beads) is again formed on the side, and a polycarbonate substrate is attached thereto. As a result of measuring the reflectance of the finished medium, the reflectance of 45% was obtained for the 780 nm wavelength light source, showing high reflectance as a recording medium. The 10mW laser (λ = 780 nm) was modulated at 0.1 μsec, 600 rpm, and 300 kHz to record. In this case, it was confirmed that the recording site was yellowish green color by electrostatic charge. After recording, the C / N ratio (CNR) was measured by reading 1.0mW laser (780nm) under the same condition.

As a result, a C / N ratio of 57 dB was obtained. This was found to be excellent recording characteristics compared to other erasable organic optical recording materials. After the optical recording medium was left at 40 ° C., 80% relative humidity for 10 days and after 10 days at −10 ° C., the result was almost 56 dB, which proved to be a stable organic optical recording medium in any environment. Also, the recording and erasing characteristics of 56 dB were obtained even when recording and reproducing were repeated 50 times.

Example 2

An optical recording medium was prepared in the same manner as in Example 1, but after the coating was formed by using a compound of formula (VI) as a full-length discoloration device (specific molecular formula is shown in Table 1 as VI-1), recording, erasing, and reliability were performed. As a result of repeating the experiments and performing the above evaluation, the reflectance was similar to that of Example 1, and the CNR was slightly decreased during the recording / erasing / reliability experiment, but it showed excellent characteristics as a recording medium compared to other recording materials.

Example 3

An optical recording medium was prepared in the same manner as in Example 1, but after the coating was formed using a compound of the general formula (IV) as a full-length discoloration device (specific molecular formula is shown in Table 1 as (IV-1)), recording, erasing, Repetition and evaluation of the reliability test resulted in excellent characteristics similar to those of Example 2.

Example 4

An optical recording medium was prepared in the same manner as in Example 1, but after the coating was formed using a compound of formula (II) as a full-length discoloration device (specific molecular formula is shown in Table 1 as (II-1)), recording, erasing, Reliability experiments were repeated and evaluated to show excellent characteristics similar to those of Example 2.

Example 5

An optical recording medium was prepared in the same manner as in Example 1, but after the coating was formed using a compound of the general formula (VII) (specific molecular formula is represented in Table 1 as (VII-1)) as a full-length discoloration device, recording, erasing, Reliability experiments were repeated.

Example 6

An optical recording medium was prepared in the same manner as in Example 1, but after the coating was formed by using a compound of the general formula (V) as a full-length discoloration device (specific molecular formula (V-1) is shown in Table 1), recording, erasing, Reliability experiments were repeated.

Example 7

An optical recording medium was prepared in the same manner as in Example 1, but after the coating was formed using a compound of the general formula (I) as a full-length discoloration device (specific molecular formula is shown in Table 1 as (I-1)), recording, erasing, Reliability experiments were repeated.

Example 8

An optical recording medium was prepared in the same manner as in Example 1, but instead of the inorganic charge generating layer 3 and the charge transport layer 4, an inorganic selenium was deposited to a thickness of 0.5 μm, and recording and erasing were performed in the same manner. Are summarized in Table 1.

Example 9

An optical recording medium was manufactured in the same manner as in Example 1, but the photomask was placed on the full-length white element 5, and the recording and erasing were performed in the same manner. On the other hand, in Example 3, other recording characteristics were similar, and the results of the high resolution of 1.2 μm showed that the effect was improved when the photomask was used.

Comparative Example 1

An optical recording medium was prepared in the same manner as in Example 1, but 25 wt% of the total length white element 5 was added to the solvent, and evaluation was performed in the same manner. As a result of the evaluation, since the transmittance due to light is lowered at a high concentration and the reflectance is relatively low, the overall recording characteristic is lower than that of the embodiment, indicating that there is a problem as a recording material.

Comparative Example 2

An optical recording medium was prepared in the same manner as in Example 1, but the resin was used for polypropylene instead of polycarbonate, and recording / erasing was performed in the same manner, but recording / erasing was impossible due to low reflectance.

TABLE 1

Claims (10)

A reflective layer, a charge generating layer, and a charge transport layer are sequentially stacked on the substrate, and a full-color discoloration element and a protective layer are stacked on top of the charge transport layer, and a charge is generated in the charge generation layer by irradiating laser light, and the charge transport layer And recording optically by discoloring the color of the full-color discoloration element. The charge generating layer is formed by dispersing at least one of polyazo, phenylene tetracarboxide, polycyclic quinone, phthalocyanine, squiarlium, and cyaryllium based resins as a charge generating material. Optical recording medium. The charge transport layer is formed by dispersing at least one of phthalocyanine, hydrazone, pyrazoline, stilbenz, triphenylmethane, heterocycle, and conjugated arylamides as a charge transport material. And an optical recording medium. The optical recording medium according to claim 2 or 3, wherein the resin is selected from polycarbonate, poly methyl methacrylate, polystyrene, and amorphous polyolefin capable of transmitting 80% or more of light in the recording wavelength band. The optical recording medium according to claim 1, wherein the full-color discoloration element is selected and used at least one of the compounds of the following general formulas (I) to (VII). (Wherein n is an integer of 4 or more; R ₁ to R ₉ are hydrogen, an alkyl group, an alkoxy group or a phenyl group; X ⁻ is ClO 4 ⁻ , BF 4 ⁻ , AsF 5 ⁻ ). The optical recording medium according to claim 1 or 5, wherein the full-color discoloration element is formed by adding 0.2 to 20% by weight with respect to the solvent. The optical recording medium according to claim 1, wherein the full-color discoloration element is formed by thinly depositing a photomask thereon. The optical recording medium according to claim 1, wherein the electric field generating layer and the charge transport layer are made of one inorganic vapor deposition layer. The optical recording medium according to claim 1, wherein a spacer is formed on the top of the full-color discoloration element to form an air layer, and a protective layer is stacked on the top of the spacer constituting the air layer. The optical recording medium according to claim 8, wherein the inorganic deposition layer is at least one of selenium, cadmium sulfide, zinc oxide, and amorphous silicon.