JP3816245B2 - Memory member - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a storage member that records information by changing optical characteristics by applying external energy.
[0002]
[Prior art]
As this type of storage member, for example, there is an optical recording medium represented by a write-once compact disc (CD-R). In general, a recording layer (light absorption layer) made of an organic dye or the like is provided on a substrate, and a reflective layer made of gold, silver or the like is further provided thereon, and laser light is irradiated as external energy. Thus, the information is recorded by changing or modifying the recording layer to change the optical characteristics. Information is optically reproduced using the difference in reflectance between the recorded portion and the unrecorded portion.
[0003]
However, since the recording layer is an organic material, there is a problem that the cost is high in terms of the cost of the material itself and the manufacturing yield.
To solve these problems, a recording layer is proposed that uses an inorganic material that is less expensive than organic dyes and that is superior in cost, such as vapor deposition or sputtering. . Examples of using such an inorganic material recording layer include those using metal sulfides (refer to Japanese Patent Laid-Open No. 4-193586), and those using sulfur and selenium (Japanese Patent Laid-Open No. 2-152029). Have been proposed).
[0004]
[Problems to be solved by the invention]
As a result of studying the storage member using the inorganic material recording layer in both the above-mentioned publications, the present inventors have found that there are problems in terms of environmental resistance and information retention as follows. It was.
That is, when the environmental resistance of a recording layer recorded with a laser beam on a recording layer using a metal sulfide (for example, SnS) was examined, high temperature and high humidity (for example, temperature 90 ° C., relative humidity 80%). When the recording layer is held for a long time (for example, 240 hours) under the (RH) condition, the recording layer is denatured by moisture absorption and swelling, so that it cannot be reproduced.
[0005]
In the case of using sulfur for the recording layer, the optical characteristics are changed by reacting sulfur with a metal (for example, silver) of the reflective layer by laser light to form a sulfide (for example, silver sulfide). Information is recorded. However, since this reaction is highly reactive, the reaction gradually proceeds even when left at room temperature to form sulfides, and the information retention becomes unstable.
[0006]
Accordingly, in view of the above problems, the present invention provides a storage member that is excellent in environmental resistance and information retention in a storage member that records information by changing optical characteristics by applying external energy. With the goal.
[0007]
[Means for Solving the Problems]
The present inventors have diligently studied the combination of various two types of substances in which information recording is performed by changing the optical characteristics by the reaction of two kinds of substances caused by the application of external energy such as light, heat, and impact. Went. As a result, it has been found that the above object can be achieved if the product generated by the reaction of two kinds of substances, that is, the third substance has a specific crystal structure.
[0008]
That is, in the first aspect of the present invention, the storage member is composed of at least a first substance and a second substance and records information by changing optical characteristics by applying external energy. The second material and the second material react with each other when external energy is applied to produce a third material having a tungsten bronze crystal structure, thereby changing the optical characteristics.
[0009]
Note that the term “consisting of at least two kinds of substances, ie, the first substance and the second substance, comprises at least one kind of each of the first substance and the second substance, or at least the first substance and the second substance. Means that the substance comprises at least one kind of substance.
According to the present invention, when external energy for storing information is applied, all or part of the first substance and the second substance react with each other, and the first and second substances involved in the reaction All or a portion of which produces a third substance. Then, at least a part of the first and second substances chemically changed due to the reaction and the generated third substance contribute to the change of the optical characteristics, and information is recorded.
[0010]
Here, in the above reaction, (1) all of the first and second substances involved in the reaction are changed to a third substance having optical properties different from those of the first and second substances. When information is recorded due to changes in the optical properties of the substance,
(2) Among the first and second substances involved in the reaction, a part of the first and second substances is changed to a third substance having optical properties different from those of the first and second substances, and the rest are the first and second substances. Is a modified product of the first and second substances whose optical characteristics do not change so much, and when information recording is performed mainly due to a change in the optical characteristics of the third substance,
(3) Of the first and second substances involved in the reaction, a part of the first and second substances is changed to a third substance that does not change much in optical properties from the first and second substances, and the rest are the first and second substances. When the substance is a modified product of the first and second substances having different optical characteristics, and information recording is performed mainly by changing the optical characteristics of the modified product,
(4) Of the first and second substances involved in the reaction, a part of the first and second substances is changed to a third substance having optical properties different from those of the first and second substances, and the rest are the first and second substances. Is a modified product of the first and second substances having different optical characteristics, and information recording may be performed by changing the optical characteristics of the third substance and the modified substance.
[0011]
The first and second substances described in claim 1 react with each other to produce a third substance having a tungsten bronze type crystal structure . That is, the first material, metals, intermetallic compounds,及 beauty, these mixtures (or three of the substance group P), or, at least one substance containing a substance of the substance group P Selected substance .
[0012]
On the other hand, the second material is an oxide,及 Beauty, compounds of that (or mixture) (or more two kinds and substance group Q), or from at least one substance containing a substance of the substance group Q is the selected material. Further, specifically, the first substance is any one of the substance group P, and includes Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr, Ba, Cr, Mn , Fe, Co, Ni, Cu, Y, lanthanoid, Nb, Ag, Zn, Cd, Hg, Al (In), Ge, Pb, Substances containing at least one of the elements (b), or these substances or a mixture of (i), or be any one material of the group of substances P, which is a substance containing at least one of mixtures of said substances (a) and substance (b).
[0013]
Here, La Ntanoido is a generic term for 15 rare earth elements leading to Lu from La of atomic number 57 71.
[0014]
On the other hand, the second substance is any one substance in the substance group Q and includes at least one of the elements Ti, V, Nb, Ta, W, Mo, Rh, and Ir ( (B), or a compound (or mixture) of these substances (b), or any one substance of the substance group Q, wherein the substances (b) and (b) it is a material comprising at least one compound (or a mixture).
[0015]
Note that if the first substance and the second substance are inorganic materials as described above, the material itself is less expensive than a memory member using an organic material such as an organic dye, and a vapor deposition method is used. And a known memory material that is advantageous in terms of cost.
Moreover, since the whole reaction which produces | generates a 3rd substance is an exothermic reaction, the reverse reaction can be made harder to occur.
Furthermore, in the memory member according to claim 1, if the first substance and the second substance are in contact with each other, when the external energy is applied, the first substance and the second substance described above This is more likely to occur and the sensitivity of the memory member can be improved.
[0016]
Further, in the memory member according to claim 1, if a substance having a decomposition temperature of 300 ° C. or less is interposed between the first substance and the second substance, the retention of information with respect to heat can be achieved. It can be made better. Here, the decomposition temperature is a temperature at which the substance is decomposed, sublimated, melted, etc. As the substance having a decomposition temperature of 300 ° C. or lower (hereinafter referred to as an intervening substance), for example, hydrocarbon or the like can be used.
[0017]
That is, by heating above the decomposition temperature by external energy, the intervening substance is decomposed, sublimated, melted, etc., the first substance and the second substance can react, and information can be recorded. By setting the temperature below the decomposition temperature before recording, the reaction of both substances below the decomposition temperature is suppressed, and the retention performance of recorded information against heat is improved.
The reason why the decomposition temperature of the intervening substance is set to 300 ° C. or lower is that if the temperature is higher than 300 ° C., the external energy applied at the time of recording must be very large, which is not practical.
[0018]
In addition, the memory member according to claim 1 includes at least two kinds of layers of a first layer containing a first substance and a second layer containing a second substance as a constituent element, or the first member It is possible to have a multi-layer structure in which a layer including both the substance and the second substance is at least one of the constituent elements.
Accordingly, a thin disk shape and a label shape can be easily configured, and can be suitably used for, for example, a write-once compact disk (CD-R).
[0019]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments shown in the drawings will be described below. The storage member according to the present embodiment is an optical storage member that records information by changing optical characteristics by the reaction of two kinds of substances caused by the application of laser light as external energy. For example, music or data may be stored as information. It can be used for a reproduction type or write once type CD that is recorded. The configuration is shown in FIG. 1 and FIG.
[0020]
As shown in FIG. 1, the optical storage member 1 has a disk shape as a whole in which a hole 2 for attachment to a CD player or the like is formed at the center. A flat portion 3 where information is not recorded is provided concentrically around the outer periphery of the hole 2, and a recording portion 4 where information is recorded and reproduced is provided concentrically around the outer periphery of the flat portion 3. .
A sectional structure of the recording unit 4 will be described with reference to FIG. 2 which is a BB section of FIG. A film (described later) is sequentially formed on a polycarbonate transparent substrate 10 formed into a disk (thickness: 1.2 mm), and laser light for recording and reproducing optical information is emitted from the substrate. Incident light from 10 as indicated by an arrow A. One surface 11 on the laser beam incident side of the substrate 10 is a mirror surface, and a spiral or concentric guide groove (track) 13 for guiding the laser beam is formed on the other surface 12.
[0021]
A WO ₃ film (second layer) 20 made of WO ₃ (second substance), which is an oxide of W (tungsten), is formed on the substrate 10 to a thickness of 190 nm. _{On the three} films 20, a La film (first layer) 30 made of a metal La (first substance), which is a lanthanoid, is formed with a film thickness of 50 nm. Further, a protective film 40 made of an ultraviolet curable resin is formed on the La film 30.
[0022]
The cross-sectional structure of the recording unit 4 is as described above, but the planar portion 3 has the same structure as the recording unit 4 except that the guide groove 13 is not formed, and the description thereof is omitted. Next, a method for manufacturing the optical storage member 1 having the above configuration will be described. First, the WO ₃ film 20 is formed on the surface 12 of the substrate 10 which is a polycarbonate disk having a mirror surface on one side and the guide groove 13 is formed on the other side by RF magnetron sputtering. (Pressure ratio): O ₂ / (Ar + O ₂ ) = 0.1, sputtering gas pressure: 3.0 × 10 ⁻³ Torr, input power: 100 to 300 W, using a W target to form 190 nm .
[0023]
Subsequently, without breaking the vacuum, the La film 30 is formed by the RF magnetron sputtering method according to the deposition conditions of gas type: Ar, sputtering gas pressure: 3.0 × 10 ⁻³ Torr, input power: 100 to 200 W. 50 nm is formed using a target.
Finally, an ultraviolet curable resin is applied by a spin coating method, and the ultraviolet curable resin is cured using a high-pressure mercury lamp to form a resin film, and the protective film 40 is formed. Thus, the optical storage member 1 is completed.
[0024]
Next, the following experiment was conducted on the information (data) holding performance of the optical storage member 1. Laser light having a wavelength of 780 nm is focused on the surface of the La film 30 from the surface 11 (mirror surface) side of the substrate 10 through the objective lens having NA (numerical aperture) = 0.50. Recorded. At this time, the linear velocity was 2.8 m / sec, the recording laser power was 13 mW, the recording frequency was 400 kHz, and the recording laser waveform was a rectangular wave with a duty ratio of 50%.
[0025]
The recorded optical storage member 1 was measured at a reproducing laser power = 0.7 mW (wavelength = 780 nm), and C / N (carrier to noise ratio), and the reflectance of an unrecorded portion and a recorded portion (recording pit). As a result, C / N = 50 dB, unrecorded portion reflectance = 63%, and recorded portion reflectance = 12%.
Further, this recorded optical storage member 1 was held for 240 hours in an environment of a temperature of 90 ° C. and a relative humidity of 80% RH as an environmental resistance test, and then again C / N, unrecorded portion reflectance, and recording When the reflectance of the partial reflectance was measured, no change was observed in any of the characteristics within the measurement error range. As described above, it was confirmed that the optical storage member 1 of the present embodiment has a recording information retention performance that is stable against heat and moisture.
[0026]
By the way, in the optical storage member 1 of the present embodiment, the recording laser beam is mainly sucked in the vicinity of the interface between the WO ₃ film 20 and the La film 30 to change the light energy into heat, and the WO ₃ film 20 is converted by this heat energy. A reaction is induced between the La film 30 and the La film 30, and all or part of the WO ₃ film 20 and the La film 30 react to change to a La _X WO ₃ (x = 0.05 to 1) film. In the present embodiment, the portion changed to the La _x WO ₃ film is formed in a pit shape as a recording portion (recording pit).
[0027]
La _X WO ₃ (third substance) which is a reaction product has a tungsten bronze type crystal structure. The crystal structure can be determined by X-ray diffraction or the like. At this time, the WO ₃ film 20 is a light-transmitting film, the La film 30 is a film having a metallic luster, and the La _X WO ₃ film is a light-absorbing film that appears blue in the visible range.
Therefore, before recording in the above experiment, the reproduction laser beam is reflected by 63% in the unrecorded portion of the recording unit 4 due to the effect of the La film 30. However, the La _X WO ₃ film absorbs light at the recording portion of the recording section 4 where the recording laser light is incident, so that only 12% of the reproduction laser light is reflected. That is, information is recorded mainly by the optical characteristic change of La _X WO ₃ which is the third substance. This is an operation capable of storing data and the like in the present embodiment.
[0028]
Since La is a light reflecting material as described above, the La film 30 as the first layer is a recording layer and also serves as a light reflecting layer that outputs recording information as a change in light reflectance. Yes.
Further, since the entire reaction is an exothermic reaction, once the reaction proceeds with the recording laser light, the energy supplied by the recording laser light can be suppressed, and as a result, the sensitivity of the storage member can be increased. At the same time, by selecting a combination of materials having large exothermic energy of reaction, the reverse reaction can be made less likely to occur.
[0029]
Further, since La _X WO ₃ is an oxide having a tungsten bronze crystal structure that is relatively stable in terms of energy, the La _X WO ₃ film that performs light absorption, that is, memory action, has excellent heat resistance. Therefore, in the optical storage member 1 of this embodiment, as a result, the thermal stability of recording information retention and the stability against moisture can be improved.
[0030]
Note that the tungsten bronze type crystal structure material, which is a reaction product, may deviate from the stoichiometric amount of oxygen as shown as La _X WO ₃ (x = 0.05 to 1) as an example.
In the present embodiment, since the first substance (La) and the second substance (WO ₃ ) are in contact with each other in a layer, the reaction between the two substances occurs when recording laser light is incident. It is more likely to occur and the recording sensitivity of the memory member can be improved.
[0031]
In addition, according to the present embodiment, since the first substance and the second substance in the reaction at the time of applying the recording laser light have a multi-layer structure in which the layers are laminated on the substrate 10, The physique can be made thin, for example, suitable for a write-once compact disc (CD-R).
(Other embodiments)
In the above embodiment, a substance having a decomposition temperature (decomposition, sublimation, melting temperature) of 300 ° C. or less (hereinafter, intervening) between the first layer (La film 30) and the second layer (WO ₃ film 20). When a third layer made of a material (for example, hydrocarbon) is interposed, the retention performance of recorded information against heat is improved for the following reason.
[0032]
That is, when the recording laser beam is heated to the decomposition temperature or higher, the intervening substance is decomposed, sublimated, melted, etc., the first substance and the second substance can react, and information can be recorded. Before recording, the reaction of both substances below the decomposition temperature is suppressed by setting the decomposition temperature or less.
Here, the decomposition temperature of the intervening material is set to 300 ° C. or lower. If the temperature is higher than 300 ° C., the power of the laser beam given at the time of recording must be very large, which is not practical as an optical storage member. Because.
[0033]
In the above embodiment, the substrate 10 is made of PET (polyethylene terephthalate), and the Ag film (second layer), the Nb ₂ O ₅ film (first layer), and the transparent protection are formed on the surface 12 of the substrate 10. A film is formed and an adhesive layer is formed on the mirror surface (surface 11).
Accordingly, when laser light is incident from the protective film side, Ag acts as the first substance and Nb ₂ O ₅ acts as the second substance, and both react at the interface to have a tungsten bronze type crystal structure. Ag _x Nb ₂ O ₅ (third substance) is generated, and memory is performed by the light absorption action of Ag _x Nb ₂ O ₅ . Therefore, after storing data and an image as information with laser light, a label configuration can be applied to an arbitrary place.
[0034]
In the above embodiment, the first layer and the second layer that react with external energy (for example, the above-described recording laser beam) are stacked on the substrate 10, but the substrate 10 is not provided. It can also be.
For example, a memory member having a two-layer structure in which a MoO ₃ film made of MoO ₃ (second material) is formed on an Al foil doped with La (first material) may be used. Accordingly, when ultrasonic waves are incident as external energy from the MoO ₃ film side, La and MoO ₃ react to generate La _x MoO ₃ (third substance) having a tungsten bronze type crystal structure, and this La _x MoO. Memory is performed by the light absorption action of ₃ . The Al foil functions as a light reflecting film.
[0035]
Further, as in the above-described embodiment, the multi-layer structure of the memory member may not be configured such that the first substance and the second substance are formed in separate layers, for example, both substances are mixed as particles or A layer mixed via a binder or the like may be at least one of the constituent elements. At the time of recording laser light irradiation, the above reaction occurs between both substance particles and functions as a memory member. Furthermore, if the binder contains the above-described intervening substance, the record holding performance by the above-described intervening substance is exhibited.
[0036]
For example, a Ce film made of lanthanoid metal Ce (first substance) is formed on one surface of a PET film, and WO ₃ fine particles (second substance) are dispersed on the film at 270 ° C. Overlapping and forming a hydrocarbon film that decomposes. And it is set as the memory member which formed the heat-resistant adhesion layer in the remaining one side of PET film.
As a result, hydrocarbon is interposed as an intervening substance between the Ce film and the WO ₃ microparticles, and Ce _x WO ₃ (third substance) having a tungsten bronze type crystal structure is produced at 270 ° C. And can be used as a thermolabel whose optical properties change. That is, heat is applied as external energy, and the temperature, which is a physical quantity, can be stored as information.
[0037]
Incidentally, in the above embodiment, the external energy for inducing reactions laser beam, is not limited to the ultrasonic or heat, light in general, electromagnetic waves, sound waves, may be radiation. Of course, the above embodiments may be appropriately combined.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an overall configuration of a memory member according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view taken along the line BB of FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Optical storage member, 2 ... Hole, 3 ... Plane part, 4 ... Recording part, 10 ... Board | substrate,
11, 12 ... surface of the substrate, 13 ... guide groove, 20 ... WO ₃ film, 30 ... La film,
40: Protective film.

Claims (1)

A storage member that includes at least a first substance and a second substance, records information by changing optical characteristics by applying external energy,
Metals, intermetallic compounds,及 Beauty, a mixture thereof and substance groups P, oxides,及 beauty, when the compound or mixture with substance groups Q,
The first substance is any one substance of the substance group P , and includes Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr, Ba, Cr, Mn, Fe, Co, Ni , Cu, Y, lanthanoid, Nb, Ag, Zn, Cd, Hg, Al, In, Ge, Pb, a substance (b) containing at least one element, or a mixture of substances (b) Or any one of the substances in the substance group P, the substance including at least one of the substance (a) and the mixture of the substances (a) ,
The second substance is any one substance in the substance group Q , and contains at least one element of Ti, V, Nb, Ta, W, Mo, Rh, and Ir (Ro ), Or a compound or mixture of the substance (b), or any one substance of the substance group Q, which is a compound or mixture of the substance (b) and the substance (b) A substance containing at least one of them ,
The first substance and the second substance react with each other when the external energy is applied to form a third substance having a tungsten bronze crystal structure to change the optical characteristics. The memory member is characterized in that the reaction for generating the third substance is an exothermic reaction.

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