JP2007141421A - Optical recording medium and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an excellent optical recording medium capable of reducing the center shifting of an inner hole when assembling an optical recording medium by eliminating a step of matching the center position of the inner hole when assembling the laminated body of the optical recording medium to work the inner hole after the formation of the laminated body, and performing good tracking servo without decentering during reproduction, and its manufacturing method. <P>SOLUTION: This method includes: a laminated body forming step of stacking a recording layer for recording information by using holography and a filter layer between first and second substrates to form a disk-like laminated body; and a through-hole forming step of forming a through-hole so that the center axis in the rotation direction of a servo track disposed in the laminated body matches the center axis of the through-hole when the through-hole is formed in the laminated body. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical recording medium on which information is recorded using holography and a method for manufacturing the same.

An optical recording medium is one of recording media capable of writing a large amount of information such as high-density image data. As this optical recording medium, for example, a rewritable optical recording medium such as a magneto-optical disk and a phase change optical disk and a write-once optical recording medium such as a CD-R have already been put into practical use. The demand for larger capacity is increasing.
However, all conventionally proposed optical recording media are two-dimensional recording, and there is a limit to increasing the recording capacity. Therefore, recently, a hologram type optical recording method capable of recording information three-dimensionally has attracted attention.
In the hologram type optical recording method, in general, information light given a two-dimensional intensity distribution and reference light having a substantially constant intensity are superposed inside a photosensitive recording layer to form them. Information is recorded by generating a distribution of optical characteristics inside the recording layer using the interference image. On the other hand, in reading (reproducing) written information, the recording layer is irradiated with only the reference light in the same arrangement as in recording, and the reproducing light having an intensity distribution corresponding to the optical characteristic distribution formed inside the recording layer is used. This is done by emitting from the recording layer.
In this hologram type optical recording method, since the optical characteristic distribution is three-dimensionally formed in the recording layer, an area where information is written by one information light, an area where information is written by other information light, and Can be partially overlapped, that is, multiplex recording is possible, which matches the demand for larger capacity. When digital volume holography is used for such multiplex recording, the signal-to-noise ratio (S / N ratio) of one spot becomes extremely high, so that the original information is faithfully maintained even if the S / N ratio is somewhat lowered by overwriting. A reproducible hologram type optical recording medium is obtained. As a result, the number of times of multiple recording reaches several hundreds, and the recording capacity of the optical recording medium can be remarkably increased (see Patent Document 1).

As such a hologram type optical recording medium, for example, as shown in FIG. 11, a servo pit pattern 3 is provided on the surface of the second substrate 1, and a reflective film 2 made of aluminum or the like is provided on the surface of the servo pit pattern. An optical recording medium 20 having a recording layer 4 on the reflecting film and a first substrate 5 on the recording layer (see Patent Document 2), or servo pits on the surface of the second substrate 1 as shown in FIG. A pattern 3 is provided, and the surface of the servo pit pattern is made of a reflective film 2 made of aluminum or the like, a first gap layer 8, a filter layer 6 on the first gap layer 8, and a second gap layer on the filter layer 6. 7 and an optical recording medium 21 having a recording layer 4 on the second gap layer 7 and a first substrate 5 on the recording layer have been proposed. FIG. 10 shows an exploded perspective view of each layer of the optical recording medium 21 shown in FIG.
As a method for manufacturing the hologram type optical recording medium, for example, as shown in FIG. 10, a second gap layer 8, a filter layer 6, a first layer is formed on a second substrate 1 having an inner hole 1 a in the center. The two gap layers 7 are formed in this order, and the openings of the inner peripheral spacer 28, the outer peripheries of the inner holes 1a and outer peripheral spacers 27, and the outer periphery of the second substrate 1 are bonded to each other on the second gap layer 7. Next, an adhesive is applied to the inner and outer peripheral spacer surfaces, and the first substrate 5 is bonded to form a laminate having a gap (cell) inside. Then, the recording layer material is injected into the cell from the injection port provided in the outer peripheral spacer 27 of the obtained laminate and cured to form the recording layer 4, thereby manufacturing the optical recording medium.
However, in the case of the optical recording medium manufactured in this way, the center of the opening of the inner peripheral spacer 28 and the inner hole 1a of the second substrate 1 may be shifted. Further, the center of the inner hole 5 a of the first substrate 5, the opening of the inner peripheral spacer 28 and the inner hole 5 a of the first substrate 5 and the inner hole 1 a of the second substrate 1 may be shifted. . If the eccentricity of the optical recording medium caused by such a center deviation is large, the servo light cannot follow the track, and the tracking servo may not function. As described above, when stacking a plurality of substrates in which inner holes are already formed, in order to make the centers of the inner holes coincide with each other with high accuracy, a process of performing centering using a high-precision jig or the like Therefore, there is a problem that production efficiency may be lowered. In addition, there is a problem that the yield of the laminated body in which the coincidence of the centers of the respective inner holes is within the allowable range is low and the yield is lowered.
Therefore, the process of aligning the center positions of the inner holes at the time of assembling the laminated body of the optical recording medium is eliminated, and the inner holes are processed after the formation of the laminated body, so that the center shift of the inner holes at the time of assembling the optical recording medium There is a demand for an excellent optical recording medium that can reduce generation and perform good tracking servo during reproduction, and an optical recording medium manufacturing method that can efficiently manufacture the optical recording medium with high accuracy. .

JP 2002-123949 A Japanese Patent Laid-Open No. 11-311936

  An object of the present invention is to solve the conventional problems and achieve the following objects. That is, the present invention eliminates the step of aligning the center positions of the inner holes at the time of assembling the laminated body of the optical recording medium, and processes the inner holes after the formation of the laminated body, thereby forming the inner holes at the time of assembling the optical recording medium. An excellent optical recording medium that can reduce the occurrence of center misalignment and can perform good tracking servo without centering during reproduction, and an optical recording medium that can efficiently manufacture the optical recording medium with high accuracy It aims at providing the manufacturing method of.

Means for solving the problems are as follows. That is,
<1> A laminate forming step of forming a disk-like laminate by laminating a recording layer for recording information using holography between a first substrate and a second substrate, and a filter layer; When forming a through hole in the laminate, a through hole is formed so that the central axis in the rotation direction of the servo track provided in the laminate coincides with the central axis of the through hole. A method for manufacturing an optical recording medium.
<2> A center mark formed on the surface of at least one of the first substrate and the second substrate and representing the position of the center axis in the rotation direction of the servo track provided in the laminate, and the center axis of the through hole The method for producing an optical recording medium according to <1>, wherein the through-hole is formed so as to coincide with.
<3> At least three points on the outermost servo track provided in the laminate are measured, and based on the measurement points, a central axis in the rotation direction of the servo track is obtained, and the central axis and the through hole The method for producing an optical recording medium according to <1>, wherein the through hole is formed so as to coincide with the central axis.
<4> The production of an optical recording medium according to any one of <1> to <3>, including a filter layer forming step of forming a filter layer comprising a laminate in which a cholesteric liquid crystal layer is laminated on a second substrate. Is the method.
<5> including a filter layer forming step of processing a filter for an optical recording medium comprising a filter layer into an optical recording medium shape, and bonding the processed filter to the second substrate to form a filter layer. To <4>. The method for producing an optical recording medium according to any one of <1> to <4>.

<6> An optical recording medium manufactured by the method for manufacturing an optical recording medium according to any one of <1> to <5>.
<7> The method according to <6>, including a first substrate and a second substrate, and having a recording layer and a filter layer between the first substrate and the second substrate. It is an optical recording medium.
<8> When the optical recording medium according to any one of <6> to <7> is irradiated with information light and reference light, the optical axis of the information light and the optical axis of the reference light are coaxial. The optical recording medium used for the optical recording method performed as described above.
<9> The optical recording medium according to any one of <6> to <8>, wherein the filter layer has a color material-containing layer containing a color material of at least one of a pigment and a dye.
<10> Any one of <6> to <9>, wherein the filter layer has a color material-containing layer containing at least one colorant of a pigment and a dye, and a cholesteric liquid crystal layer on the color material-containing layer. The optical recording medium described in 1.
<11> The optical recording medium according to any one of <9> to <10>, wherein the color material is a red pigment.
<12> The optical recording medium according to <11>, wherein a red pigment has a transmittance of 532 nm light of 33% or less and a transmittance of 655 nm light of 66% or more.
<13> The optical recording medium according to any one of <9> to <12>, wherein the filter layer has a dielectric vapor deposition layer on the color material-containing layer.
<14> The optical recording medium according to any one of <9> to <13>, wherein the color material-containing layer contains a binder resin, and the binder resin is a polyvinyl alcohol resin.
<15> The optical recording medium according to any one of <9> to <14>, wherein the color material-containing layer surface is rubbed.
<16> The optical recording medium according to any one of <6> to <15>, wherein the filter layer includes a dielectric vapor deposition layer in which a plurality of dielectric thin films having different refractive indexes are stacked.
<17> The optical recording medium according to <16>, wherein the dielectric vapor deposition layer is formed by alternately laminating a plurality of high refractive index dielectric thin films and low refractive index dielectric thin films.
<18> The optical recording medium according to any one of <16> to <17>, wherein the dielectric vapor deposition layer is a laminate of 2 to 20 dielectric thin films.
<19> The optical recording medium according to any one of <6> to <18>, wherein the filter layer includes a single cholesteric liquid crystal layer.
<20> The optical recording medium according to any one of <6> to <19>, wherein the filter layer is a laminate in which two or more cholesteric liquid crystal layers are laminated.
In the optical recording medium described in <20>, two or more cholesteric liquid crystal layers are laminated, and information light used at the time of recording or reproduction does not cause a shift in the selective reflection wavelength even when the incident angle changes. In addition, since the reference light and the reproduction light do not reach the reflection film, it is possible to prevent the generation of diffused light due to irregular reflection on the reflection surface. Therefore, the noise generated by the diffused light is not superimposed on the reproduced image and detected on the CMOS sensor or CCD, but the reproduced image can be detected at least to the extent that error correction is possible. The noise component due to diffused light becomes a serious problem as the multiplicity of holograms increases. That is, as the multiplicity increases, for example, when the multiplicity is 10 or more, the diffraction efficiency from one hologram becomes extremely small, and if there is diffusion noise, the detection of the reproduced image becomes very difficult. According to this configuration, such difficulty can be eliminated, and high density image recording that has never been achieved can be realized.
<21> The optical recording medium according to any one of <19> to <20>, wherein the selective reflection wavelength band in the cholesteric liquid crystal layer is continuous.
<22> The optical recording medium according to any one of <19> to <21>, wherein the cholesteric liquid crystal layer contains at least a nematic liquid crystal compound and a photoreactive chiral compound.
<23> The optical recording medium according to any one of <19> to <23>, wherein the cholesteric liquid crystal layer has circularly polarized light separation characteristics.
<24> The optical recording medium according to any one of <19> to <23>, wherein the rotation directions of the spirals in the cholesteric liquid crystal layer are the same.
<25> The optical recording medium according to any one of <19> to <24>, wherein the selective reflection center wavelengths in the cholesteric liquid crystal layer are different from each other.
<26> The optical recording medium according to any one of <19> to <25>, wherein the selective reflection wavelength bandwidth in the cholesteric liquid crystal layer is 100 nm or more.
<27> The optical recording medium according to any one of <6> to <26>, wherein the filter layer transmits the first light and reflects a second light different from the first light.
<28> The optical recording medium according to <27>, wherein the wavelength of the first light is 350 to 600 nm and the wavelength of the second light is 600 to 900 nm.
<29> The light transmittance at 655 nm for light within ± 40 ° in the filter layer is 50% or more, and the light reflectance at 532 nm is 30% or more. <6> to <28> An optical recording medium according to any one of the above.
<30> Any one of <6> to <29>, wherein the filter layer has a light transmittance at 655 nm of 50% or more at an incident angle of ± 40 ° and a light reflectance at 532 nm of 30% or more. The optical recording medium described in 1.
_{<31> λ 0 ~λ 0 /} cos20 ° filter layer (where, lambda ₀ represents a wavelength of the irradiated light) according to any one the light reflectance is 40% or more from the <6> to <30> in It is an optical recording medium.
_{<32> λ 0 ~λ 0 /} cos40 ° filter layer (where, lambda ₀ represents a wavelength of the irradiated light) according to any one of <31> light reflectance at the, the items <6> is 40% or more This is an optical recording medium.
<33> The optical recording medium according to any one of <6> to <32>, wherein the filter layer is used as a selective reflection film of an optical recording medium that records information using holography.
<34> The filter layer has a photoreactive chiral compound, the photoreactive chiral compound has a chiral moiety and a photoreactive group, and the chiral moiety is composed of an isosorbide compound, an isomannide compound, and a binaphthol compound. The optical recording medium according to any one of <6> to <33>, which is at least one selected.
<35> The optical recording medium according to <34>, wherein the photoreactive group is a group that causes isomerization of a carbon-carbon double bond from trans to cis upon irradiation with light.
<36> The optical recording medium according to any one of <6> to <35>, wherein the second substrate has a servo pit pattern.
<37> The optical recording medium according to <36>, wherein the servo pit pattern has a reflective film on the surface.
<38> The optical recording medium according to <37>, wherein the reflective film is a metal reflective film.
<39> The optical recording medium according to any one of <6> to <38>, wherein a first gap layer for smoothing a second substrate surface is provided between the filter layer and the reflective film.
<40> The optical recording medium according to any one of <6> to <39>, wherein a second gap layer is provided between the recording layer and the filter layer.

<41> Irradiation of the information light and the reference light to the optical recording medium according to any one of <6> to <40> is performed so that the optical axis of the information light and the optical axis of the reference light are coaxial. This is an optical recording method characterized by being performed.
<42> The optical recording method according to <41>, wherein the optical recording medium is a reflection hologram.

<43> The recording information corresponding to the interference image is reproduced by irradiating the interference image formed on the recording layer by the optical recording method according to any one of <6> to <40> with the same reproduction light as the reference light. It is the optical reproduction method characterized by doing.
<44> The light according to <43>, wherein the reproduction light is irradiated at the same angle as the reference light used for recording on the optical recording medium to irradiate the interference image on the interference image to reproduce the recorded information. It is a playback method.

  According to the present invention, various problems in the prior art can be solved, the step of matching the center positions of the inner holes at the time of assembling the laminated body of the optical recording medium is eliminated, and the inner holes are processed after the laminated body is formed. An excellent optical recording medium that reduces the occurrence of center misalignment of the inner hole during the assembly of the medium and that can perform good tracking servo without centering during reproduction, and efficiently manufactures the optical recording medium with high accuracy It is possible to provide a method for manufacturing an optical recording medium that can be used.

(Method for producing optical recording medium)
The method for producing an optical recording medium of the present invention includes a disc-shaped laminate in which a recording layer for recording information using a holography and a filter layer are laminated between a first substrate and a second substrate. When the through hole is formed in the laminate, the central axis in the rotation direction of the servo track provided in the laminate coincides with the central axis of the through hole. And other steps such as a composition preparation step, a recording layer laminating step, a filter layer forming step, and a gap layer laminating step, which are appropriately selected as necessary. It is characterized by including.

<Composition preparation process>
The composition preparation step is a step of preparing a composition for optical recording, and includes a photopolymer composed of a monomer, a photoinitiator, a sensitizer, an oligomer and a binder, and other components appropriately selected as necessary. An optical recording composition is prepared by dissolving, dispersing, mixing, etc. with a solvent. As the preparation conditions, for example, the temperature is 23 ° C., the humidity is 10%, and the drying is performed in a low temperature environment.

<Recording layer lamination process>
The recording layer laminating step is a step of laminating a recording layer for recording information by holography on the second gap layer when the second gap layer is laminated on the filter layer or the filter layer. It is a step of laminating the optical recording composition prepared in the composition preparation step by coating or the like.
The method for laminating the recording layer is not particularly limited and can be appropriately selected depending on the purpose. For example, the recording layer is laminated on a support made of a wet film-forming method or an injection method, a film, or the like. A laminating method in which a sheet body is produced and the sheet body is attached is exemplified.
The wet film forming method is a method of forming (using and drying) a solution (recording layer solution) in which a recording layer material described later is dissolved or dispersed in a solvent. There is no particular limitation, and it can be appropriately selected from known ones according to the purpose. For example, an inkjet method, a spin coating method, a kneader coating method, a bar coating method, a blade coating method, a casting method, a dip method, a curtain Examples include a coating method.
The injection method is a method of injecting the recording layer solution into the gap between the first substrate and the second substrate. The outer peripheral spacer is previously sandwiched between the first substrate and the second substrate to form a disk cell, and a notch is provided in a part of the outer peripheral spacer, and the recording layer solution is injected using the opening as an inlet.
There is no restriction | limiting in particular as said injection | pouring method, According to the objective, it can select suitably, For example, the outer periphery injection method, the inner periphery injection method, a gap injection method etc. are mentioned.
Examples of the injection conditions include a temperature of 23 ° C., a viscosity of 330 mPa · s, a pressure of 0.5 MPa, a humidity of 10%, and a curing time of a temperature of 80 ° C. for 40 minutes.
There is no restriction | limiting in particular as said injection | pouring apparatus, According to the objective, it can select suitably, For example, a syringe, an air pressure dispenser, etc. are mentioned.

  The laminating method for attaching the sheet body is not particularly limited and can be appropriately selected depending on the purpose. For example, the optical recording composition is applied to a film-like support to form a laminate. And a method of punching the laminate into a disk shape to form a sheet body and sticking the sheet body. This laminating method has an advantage that the thickness of the recording layer can be made uniform from the point that the recording layer is previously formed to a certain thickness and then processed and pasted into a predetermined shape.

There is no restriction | limiting in particular as thickness of the said recording layer, According to the objective, it can select suitably, 1-1000 micrometers is preferable and 100-700 micrometers is more preferable.
When the thickness of the recording layer is within the preferable numerical range, a sufficient S / N ratio can be obtained even when 10 to 300 multiple shift multiplexing is performed, and when the thickness is within the more preferable numerical range, this is remarkable. It is advantageous in some respects.
The thickness measurement method and the measurement device are not particularly limited and can be appropriately selected according to the purpose.For example, as a measurement method, a caliper measurement, a micrometer measurement, a laser film thickness measurement method, a measurement device, A caliper, a micrometer, a laser film thickness meter, etc. are mentioned.

-Outer spacer-
The shape of the outer peripheral spacer is not particularly limited as long as the outer periphery is substantially the same as the outer peripheral shape of the optical recording medium, and can be appropriately selected according to the purpose. Is mentioned. Among these, a circle is preferable.
Examples of the cross-sectional shape of the outer peripheral spacer include a quadrangle, a rectangle, a trapezoid, a circle, and an ellipse. Among these, a quadrangle, a trapezoid, a rectangle, and the like are preferable from the viewpoint of the effect of making the thickness constant. The outer peripheral spacer 27 shown in FIG. 8 is an example of a square cross section.
There is no restriction | limiting in particular as the thickness of the said outer periphery spacer 27, According to the objective, it can select suitably, For example, it is preferable that it is the thickness substantially the same as the thickness of the said recording layer. Specifically, the thickness is preferably 100 to 1,000 μm, which is the same as the thickness of the recording layer.
The width of the outer peripheral spacer is not particularly limited as long as it is at least 0.5 mm, and can be appropriately selected according to the purpose. For example, 0.5 to 5 mm is preferable, and 0.5 to 3 mm is more preferable. 0.5-2 mm is particularly preferable. When the width is less than 0.5 mm, the holding function for keeping the recording layer thickness constant may be reduced in terms of mechanical strength and support area. As a result, the recording capacity may be reduced.

There is no restriction | limiting in particular as a material of the said outer periphery spacer 27, Although both an inorganic material and an organic material can be used suitably, the said organic material is preferable from the point of a moldability and cost.
Examples of the inorganic material include glass, ceramic, quartz, and silicon.
The organic material is not particularly limited and may be appropriately selected according to the purpose. , Polyamide resin, polyimide resin, polyolefin resin, acrylic resin, polynorbornene resin, cellulose resin, polyarylate resin, polystyrene resin, polyvinyl alcohol resin, polyvinyl chloride resin, polyvinylidene chloride Examples thereof include resins and polyacrylic resins. These may be used alone or in combination of two or more. Among these, polycarbonate resins and acrylic resins are preferable from the viewpoints of moldability, peelability, and cost.

  There is no restriction | limiting in particular as a manufacturing method of the said outer periphery spacer 27, According to the objective, it can select suitably, For example, injection molding, blow molding, compression molding, a vacuum forming die extrusion process, a cutting process etc. are mentioned. .

-First substrate-
The shape, structure, size, etc. of the first substrate are not particularly limited and can be appropriately selected according to the purpose. Examples of the shape include a disk shape, a card shape, a flat plate shape, The structure may be a single layer structure or a laminated structure, and the size may be appropriately selected according to the size of the optical recording medium. Can do.

The material for the first substrate is not particularly limited, and any of inorganic materials and organic materials can be suitably used. However, the mechanical strength of the optical recording medium can be ensured for recording and reproduction. In the case of a transmission type in which the light used is incident through the substrate, it is necessary that the light used is sufficiently transparent in the wavelength region of the light used.
Examples of the inorganic material include glass, quartz, and silicon.
Examples of the organic material include acetate resins such as triacetyl cellulose, polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, and acrylic resins. Polynorbornene resin, cellulose resin, polyarylate resin, polystyrene resin, polyvinyl alcohol resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyacrylic resin, polylactic acid resin, plastic film laminated paper And synthetic paper. These may be used alone or in combination of two or more. Among these, polycarbonate resins and acrylic resins are preferable from the viewpoints of moldability, optical characteristics, and cost.

As said 1st board | substrate, what was synthesize | combined suitably may be used and a commercial item may be used.
There is no restriction | limiting in particular as thickness of said 1st board | substrate, According to the objective, it can select suitably, 0.1-5 mm is preferable and 0.3-2 mm is more preferable. If the thickness of the substrate is less than 0.1 mm, distortion of the shape during storage of the disk may not be suppressed. If the thickness exceeds 5 mm, the weight of the entire disk increases and is rotated by a drive motor or the like. In some cases, an excessive load may be applied.

-Second substrate-
The shape, structure, size and the like of the second substrate are not particularly limited and can be appropriately selected according to the purpose. Examples of the shape include a disk shape and a card shape. It is necessary to select a material that can ensure the mechanical strength of the optical recording medium. In addition, when light used for recording and reproduction enters through the substrate, it is necessary to be sufficiently transparent in the wavelength region of the light used.
As the material for the second substrate, glass, ceramics, resin, or the like is usually used, but resin is particularly preferable from the viewpoint of moldability and cost.
Examples of the resin include polycarbonate resin, acrylic resin, epoxy resin, polystyrene resin, acrylonitrile-styrene copolymer, polyethylene resin, polypropylene resin, silicone resin, fluorine resin, ABS resin, and urethane resin. Among these, polycarbonate resin and acrylic resin are particularly preferable from the viewpoints of moldability, optical characteristics, and cost.
As said 2nd board | substrate, what was synthesize | combined suitably may be used and a commercial item may be used.

  In the second substrate, address-servo areas as a plurality of positioning areas extending linearly in the radial direction are provided at predetermined angular intervals, and a sector-shaped section between adjacent address-servo areas becomes a data area. ing. In the address-servo area, information for performing focus servo and tracking servo by the sampled servo method and address information are recorded in advance by embossed pits (servo pits) (preformat). Note that the focus servo can be performed using the reflective surface of the reflective film. As information for performing the tracking servo, for example, a wobble pit can be used. If the optical recording medium has a card shape, the servo pit pattern may be omitted.

  There is no restriction | limiting in particular as thickness of said 2nd board | substrate, According to the objective, it can select suitably, 0.1-5 mm is preferable and 0.3-2 mm is more preferable. If the thickness of the substrate is less than 0.1 mm, distortion of the shape during storage of the disk may not be suppressed. If the thickness exceeds 5 mm, the weight of the entire disk increases and an excessive load is applied to the drive motor. Sometimes.

-Recording layer-
The recording layer can record information using holography, and when irradiated with electromagnetic waves of a predetermined wavelength (γ rays, X-rays, ultraviolet rays, visible rays, infrared rays, radio waves, etc.), depending on the intensity thereof A material whose optical characteristics such as an extinction coefficient and a refractive index change is used.

  The recording layer material includes a photopolymer and other components appropriately selected as necessary.

-Photopolymer-
Examples of the photopolymer include those that undergo a polymerization reaction upon irradiation with light and are polymerized, and those that decompose upon irradiation with light, and are not particularly limited and may be appropriately selected depending on the purpose. And a photoinitiator and, if necessary, other components such as a sensitizing dye, an oligomer and a binder.

Examples of the photopolymer include “Photopolymer Handbook” (Industry Research Society, 1989), “Photopolymer Technology” (Nikkan Kogyo Shimbun, 1989), SPIE Proceedings Vol. 3010 p354-372 (1997), and SPIE Proceedings Vol. 3291 p89-103 (1998). Also, U.S. Pat. Nos. 5,759,721, 4,942,112, 4,959,284, 6,221,536, U.S. Pat. No. 6,743,552, WO 97/44714 pamphlet, 97/13183 pamphlet, 99/26112 pamphlet, 97/13183 pamphlet, Japanese Patent No. 2880342, pamphlet Examples include photopolymers described in Japanese Patent Nos. 2873126, 2849021, 3057082, 3161230, 2001-316416, 2000-275859, and the like.

-Monomer-
The monomer is not particularly limited and may be appropriately selected depending on the purpose. For example, a radical polymerization type monomer having an unsaturated bond such as an acryl group or a methacryl group, an epoxy ring or an oxetane ring. Examples thereof include a cationic polymerization type monomer having an ether structure. These monomers may be monofunctional or polyfunctional. Moreover, what utilized the photocrosslinking reaction may be used.

  Examples of the radical polymerization type monomer include acryloylmorpholine, phenoxyethyl acrylate, isobornyl acrylate, 2-hydroxypropyl acrylate, 2-ethylhexyl acrylate, 1,6-hexanediol diacrylate, tripropylene glycol diacrylate, neo Pentyl glycol PO modified diacrylate, 1,9-nonanediol diacrylate, hydroxypivalate neopentyl glycol diacrylate, EO modified bisphenol A diacrylate, polyethylene glycol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, pentaerythritol hexa Acrylate, EO-modified glycerol triacrylate, trimethylol group Pantriacrylate, EO-modified trimethylolpropane triacrylate, 2-naphth-1-oxyethyl acrylate, 2-carbazoyl-9-ylethyl acrylate, (trimethylsilyloxy) dimethylsilylpropyl acrylate, vinyl-1-naphthoate, N-vinyl Examples thereof include carbazole, 2,4,6-tribromophenyl acrylate, pentabromo acrylate, phenylthioethyl acrylate, and tetrahydrofurfuryl acrylate.

  Examples of the cationic polymerization type monomer include bisphenol A epoxy resin, phenol novolac epoxy resin, glycerol triglycidyl ether, 1,6-hexane glycidyl ether, vinyltrimethoxysilane, 4-vinylphenyltrimethoxysilane, and γ-methacrylic acid. Examples include loxypropyltriethoxysilane and compounds represented by the following structural formulas (M1) to (M6). These monomers may be used individually by 1 type, and may use 2 or more types together.

-Photoinitiator-
The photoinitiator is not particularly limited as long as it has sensitivity to recording light, and examples thereof include materials that cause radical polymerization, cationic polymerization, crosslinking reaction, and the like by light irradiation.
Examples of the photoinitiator include 2,2′-bis (o-chlorophenyl) -4,4 ′, 5,5′-tetraphenyl-1,1′-biimidazole, 2,4,6-tris ( Trichloromethyl) -1,3,5-triazine, 2,4-bis (trichloromethyl) -6- (p-methoxyphenylvinyl) -1,3,5-triazine, diphenyliodonium tetrafluoroborate, diphenyliodonium hexafluoro Phosphate, 4,4'-di-t-butyldiphenyliodonium tetrafluoroborate, 4-diethylaminophenylbenzenediazonium hexafluorophosphate, benzoin, 2-hydroxy-2-methyl-1-phenylpropan-2-one, benzophenone, thioxanthone 2,4,6-trimethylbenzoyldipheny Acylphosphine oxide, triphenylbutylborate tetraethylammonium, bis (η-5-2,4-cyclopentadien-1-yl), bis [2,6-difluoro-3- (1H-pyrrol-1-yl) phenyltitanium ], Diphenyl-4-phenylthiophenylsulfonium hexafluorophosphate, and the like. These may be used alone or in combination of two or more. Moreover, you may use a sensitizing dye together according to the wavelength of the light to irradiate.

-Sensitizing dye-
Examples of the sensitizing dye include “Research Disclosure, Vol. 200, December 1980, Item 20036” and “sensitizer” (p. 160 to p. 163, Kodansha; Katsumi Tokumaru, Nobu Okawara, edited by 1987. ) And the like can be used.

Examples of the sensitizing dye include spectral sensitizing dyes. Examples of the spectral sensitizing dye include 3-ketocoumarin compounds described in JP-A No. 58-15603, thiopyrylium salts described in JP-A No. 58-40302, JP-B Nos. 59-28328 and 60- Naphthothiazole merocyanine compounds described in JP-A-53300, merocyanine compounds described in JP-B-61-9621, JP-A-62-3842, JP-A-59-89303, and JP-A-60-60104. .
In addition, the dyes described in “Chemicals of Functional Dyes” (1981, CMC Publishing Co., p.393-p.416) and “Coloring Materials” (60 [4] 212-224 (1987)) are also included. Specific examples include cationic methine dyes, cationic carbonium dyes, cationic quinoneimine dyes, cationic indoline dyes, and cationic styryl dyes.
In addition, coumarin (including ketocoumarin or sulfonocoumarin) dyes, melostyryl dyes, oxonol dyes, hemioxonol dyes and other keto dyes; non-ketopolymethine dyes, triarylmethane dyes, xanthene dyes, anthracene dyes, rhodamine dyes, acridine dyes Non-keto dyes such as dyes, aniline dyes, azo dyes; non-ketopolymethine dyes such as azomethine dyes, cyanine dyes, carbocyanine dyes, dicarbocyanine dyes, tricarbocyanine dyes, hemicyanine dyes, styryl dyes; azine dyes, oxazine dyes, Quinoneimine dyes such as thiazine dyes, quinoline dyes and thiazole dyes are also included in the spectral sensitizing dyes.
The spectral sensitizing dyes may be used alone or in combination of two or more.

-Binder resin-
The binder resin is used for the purpose of enhancing the effect of improving the coating properties, film strength, and hologram recording characteristics, and is appropriately selected in consideration of compatibility with the hologram material and the photothermal conversion substance. There is no restriction | limiting in particular as said binder resin, According to the objective, it can select suitably from well-known things. For example, polyvinyl alcohol resin, gelatin, vinyl chloride / vinyl acetate copolymer; vinyl chloride, copolymer of vinyl acetate and at least one of vinyl alcohol, maleic acid and acrylic acid; vinyl chloride / vinylidene chloride copolymer; Vinyl / acrylonitrile copolymer; ethylene / vinyl acetate copolymer; cellulose derivatives such as nitrocellulose resin; polyacrylic resin, polyvinyl acetal resin, polyvinyl butyral resin, epoxy resin, phenoxy resin, polyurethane resin, polycarbonate resin, novolac resin, Examples include soluble nylon, polystyrene resin, melamine resin, and formalin resin. These may be used alone or in combination of two or more. In order to enhance the dispersibility and durability Moreover, in the binder resin molecules listed above, the polar group (epoxy _{group, CO 2 H, OH, NH} 2, SO 3 M, OSO 3 M, PO 3 M 2, Those having introduced OPO ₃ M ₂ (wherein M is a hydrogen atom, an alkali metal, or ammonium and may be different from each other when a plurality of M are present in one group) are preferred. The content of is preferably 10 ⁻⁶ to 10 ⁻⁴ equivalents per gram of binder resin, and the binder resins listed above may be cured by adding a known cross-linking agent such as a hemiacetal or isocyanate. .

There is no restriction | limiting in particular as content of the binder in solid content of the said recording layer, According to the objective, it can select suitably, For example, it is preferable that it is 10-95 mass%, and it is 35-90 mass%. More preferably. If the content is less than 10% by mass, a stable interference image may not be obtained, and if it exceeds 95% by mass, desirable performance may not be obtained in terms of diffraction efficiency.
The content of the binder in the photosensitive layer is preferably 10 to 95% by mass and more preferably 35 to 90% by mass in the total solid content of the photosensitive layer.

-Polymerization inhibitor and antioxidant-
In order to improve the storage stability of the recording layer, a photopolymer polymerization inhibitor or an antioxidant may be added. Examples of polymerization inhibitors and antioxidants include hydroquinone, p-benzoquinone, hydroquinone monomethyl ether, 2,6-ditertiary-butyl-p-cresol, 2,2'-methylenebis (4-methyl-6-tertiary-butylphenol). , Trifel phosphite, trisnonylphenyl phosphite, phenothiazine, N-isopropyl-N′-phenyl-p-phenylenediamine and the like. The amount used is within 3% by mass with respect to the total amount of monomers used in the composition.

-Other components contained in the recording layer-
A photothermal conversion material can also be included for the purpose of improving the sensitivity of the recording layer. As the photothermal conversion material, the description in Japanese Patent Application No. 2005-84780 can be referred to.
Moreover, in order to relieve the volume change at the time of polymerization, a component that diffuses in a direction opposite to the polymerization component may be added, or a compound having an acid cleavage structure may be added separately in addition to the polymer.

--Curing of recording layer--
The method for curing the recording layer is not particularly limited as long as it is a heat treatment, and can be appropriately selected according to the purpose. Heat at 30 ° C. for 30 to 360 minutes to cure the recording layer. When the heating temperature is less than 40 ° C., the photopolymer of the recording layer may not be cross-linked, or the cross-linking speed may be slow and the cross-linking may not be completed. The hologram recording sensitivity may decrease.
The reason why the recording layer was cured by heat treatment and the curing method using ultraviolet rays was not used was that when the recording layer was cured with ultraviolet rays, the hologram recording sensitivity was lowered due to the mechanism that the monomer of the recording layer caused photopolymerization. Because.

<Filter layer forming step>
The filter layer forming step is a step of forming a filter layer by processing an optical recording medium filter into an optical recording medium shape and bonding the processed filter to the second substrate. Here, the optical recording medium filter is as described later. In some cases, the step of forming the filter layer directly on the substrate may be employed. For example, the color material-containing layer is applied on the substrate to form the color material-containing layer, and the color material-containing layer is formed on the color material-containing layer. Examples thereof include a method of forming a dielectric deposited film by a sputtering method.
Examples of the optical recording medium shape include a disk shape and a card shape, and the processing is not particularly limited, and can be appropriately selected according to the purpose. For example, a cutting process using a press cutter, a punching cutter Punching by, etc. are mentioned. In the bonding, for example, an adhesive, a pressure-sensitive adhesive, or the like is used to attach a filter to the substrate so that bubbles do not enter.
The adhesive is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include various adhesives such as a UV curable type, an emulsion type, a one-component curable type, and a two-component curable type, Known adhesives can be used in any combination.
There is no restriction | limiting in particular as said adhesive, According to the objective, it can select suitably, For example, a rubber adhesive, an acrylic adhesive, a silicone adhesive, a urethane adhesive, a vinyl alkyl ether adhesive , Polyvinyl alcohol pressure sensitive adhesive, polyvinyl pyrrolidone pressure sensitive adhesive, polyacrylamide pressure sensitive adhesive, cellulose pressure sensitive adhesive, and the like.
The application thickness of the adhesive or the pressure-sensitive adhesive is not particularly limited and can be appropriately selected according to the purpose. From the viewpoint of optical properties and thinning, 0.1 to 10 μm is preferable in the case of an adhesive, 0.1-5 micrometers is more preferable. Moreover, in the case of an adhesive, 1-50 micrometers is preferable and 2-30 micrometers is more preferable.

-Filter for optical recording media-
The filter for an optical recording medium prevents irregular reflection from the reflection film of the optical recording medium by information light and reference light without causing a shift in the selective reflection wavelength even when the incident angle changes, and prevents the generation of noise. There is a function. By laminating a filter layer in the optical recording medium using the optical recording medium filter, optical recording with high resolution and excellent diffraction efficiency can be obtained.
The function of the filter layer laminated in the optical recording medium is preferably to transmit the first light and reflect the second light different from the first light, and the wavelength of the first light is It is preferable that it is 350-600 nm and the wavelength of 2nd light is 600-900 nm. For that purpose, it is preferable that the optical recording medium has a structure in which a recording layer, a filter layer, and a servo bit pattern are laminated in this order as viewed from the optical system side.
Further, the filter layer preferably has a light transmittance at 655 nm of 50% or more, more preferably 80% or more, and a light reflectance at 532 nm of 30% or more, preferably 40%, at an incident angle of ± 40 °. The above is more preferable.
There is no restriction | limiting in particular as said filter layer, According to the objective, it can select suitably, For example, lamination | stacking of a dielectric vapor deposition layer, a single layer or two or more cholesteric liquid crystal layers, and also other layers as needed Formed by the body. Moreover, you may have a color material content layer.

-Dielectric deposition layer-
The dielectric vapor deposition layer is formed by laminating a plurality of dielectric thin films having different refractive indexes. In order to obtain a wavelength selective reflection film, a dielectric thin film having a high refractive index and a dielectric thin film having a low refractive index are used. Although it is preferable to laminate a plurality of layers alternately, it is not limited to two or more types, and may be more types. Moreover, when providing a color material content layer, it forms under a dielectric material vapor deposition layer.
The number of stacked layers is preferably 2 to 20 layers, more preferably 2 to 12 layers, still more preferably 4 to 10 layers, and particularly preferably 6 to 8 layers. If the number of stacked layers exceeds 20, the production efficiency may decrease due to multi-layer deposition, and the objects and effects of the present invention may not be achieved.

  The order of lamination of the dielectric thin films is not particularly limited and can be appropriately selected according to the purpose. For example, when the refractive index of an adjacent film is high, a film having a lower refractive index is first laminated. To do. Conversely, when the refractive index of the adjacent layer is low, a film having a higher refractive index is first laminated. The threshold value for determining whether the refractive index is high or low is preferably 1.8. Note that whether the refractive index is high or low is not absolute. Among high-refractive-index materials, there may be a material with a relatively high refractive index and a material with a relatively low refractive index, which are used alternately. May be.

The material for the high refractive index dielectric thin film is not particularly limited and may be appropriately selected depending on the intended purpose. For example, Sb ₂ O ₃ , Sb ₂ S ₃ , Bi ₂ O ₃ , CeO ₂ , CeF _{3, HfO 2, La 2 O} 3, Nd 2 O 3, Pr 6 O 11, Sc 2 O 3, SiO, Ta 2 O 5, TiO 2, TlCl, Y 2 O 3, ZnSe, ZnS, ZrO 2 , etc. Can be mentioned. Among these, Bi ₂ O ₃ , CeO ₂ , CeF ₃ , HfO ₂ , SiO, Ta ₂ O ₅ , TiO ₂ , Y ₂ O ₃ , ZnSe, ZnS, ZrO ₂ are preferable, and among these, SiO, Ta ₂ O ₅ , TiO ₂ , Y ₂ O ₃ , ZnSe, ZnS, and ZrO ₂ are more preferable.

The material for the low refractive index dielectric thin film is not particularly limited and may be appropriately selected depending on the intended purpose. For example, Al ₂ O ₃ , BiF ₃ , CaF ₂ , LaF ₃ , PbCl ₂ , PbF ₂ , LiF, MgF ₂ , MgO, NdF ₃ , SiO ₂ , Si ₂ O ₃ , NaF, ThO ₂ , ThF _{4 and the} like. Among these, Al ₂ O ₃ , BiF ₃ , CaF ₂ , MgF ₂ , MgO, SiO ₂ , Si ₂ O ₃ are preferable, and among these, Al ₂ O ₃ , CaF ₂ , MgF ₂ , MgO, SiO ₂ , Si ₂ O ₃ is more preferable.
In the dielectric thin film material, the atomic ratio is not particularly limited and can be appropriately selected according to the purpose. The atomic ratio can be adjusted by changing the atmospheric gas concentration during film formation. .

The method for forming the dielectric thin film is not particularly limited and may be appropriately selected depending on the purpose. For example, a physical vapor deposition method such as ion plating, vacuum deposition using an ion beam, sputtering, or the like. (PVD method), chemical vapor deposition method (CVD method) and the like. Among these, vacuum deposition and sputtering are preferable, and sputtering is more preferable.
As the sputtering, a DC sputtering method having a high film formation rate is preferable. In the DC sputtering method, it is preferable to use a material having high conductivity.
In addition, as a method for forming a multilayer film by sputtering, for example, (1) a one-chamber method in which a plurality of targets are alternately or sequentially formed in one chamber, and (2) continuous film formation in a plurality of chambers. There is a multi-chamber method. Among these, the multi-chamber method is particularly preferable from the viewpoint of preventing productivity and material contamination.
The thickness of the dielectric thin film is preferably λ / 16 to λ, more preferably λ / 8 to 3λ / 4, and particularly preferably λ / 6 to 3λ / 8 in the optical wavelength order.

-Cholesteric liquid crystal layer-
The cholesteric liquid crystal layer contains at least a cholesterol derivative, or a nematic liquid crystal compound and a chiral compound, and further contains a polymerizable monomer and, if necessary, other components.
The cholesteric liquid crystal layer may be either a single-layer cholesteric liquid crystal layer or two or more cholesteric liquid crystal layers.

  The cholesteric liquid crystal layer preferably has a circularly polarized light separation function. The cholesteric liquid crystal layer having the function of separating circularly polarized light has only a circularly polarized light component in which the rotation direction (clockwise or counterclockwise) of the liquid crystal is coincident with the circular polarization direction and the wavelength is the helical pitch of the liquid crystal. Has a selective reflection characteristic of reflecting the light. Using the selective reflection characteristics of the cholesteric liquid crystal layer, only circularly polarized light having a specific wavelength is transmitted and separated from natural light in a certain wavelength band, and the rest is reflected.

In the filter for optical recording medium, the normal incidence 0 ° and to ± 20 ° range at which λ ₀ ~λ _{0 /} cos20 ° (but, lambda ₀ represents a wavelength of the irradiated light) in the light reflectance of 40% or more preferably there, lambda ₀ to [lambda] a perpendicular incidence in the range of ± 40 ° and ₀ ° 0 _/ cos40 ° (However, lambda ₀ represents a wavelength of the irradiated light) that light reflectance at not less than 40% Particularly preferred. Wherein λ ₀ ~λ ₀ / cos20 °, especially λ ₀ ~λ ₀ / cos40 ° (However, lambda ₀ represents a wavelength of the irradiated light) If the light reflectance is 40% or more at the angular dependence of the irradiation light reflected The lens optical system used for a normal optical recording medium can be employed. For this purpose, it is preferable that the selective reflection wavelength width of the cholesteric liquid crystal layer is large.
Specifically, in the case of a single-layer cholesteric liquid crystal layer, the selective reflection wavelength region width Δλ of the cholesteric liquid crystal layer is expressed by the following formula 1, and therefore it is preferable to use a liquid crystal having a large (ne-no). .
<Formula 1>
Δλ = 2λ (ne−no) / (ne + no)
In Equation 1, no represents the refractive index of nematic liquid crystal molecules contained in the cholesteric liquid crystal layer with respect to normal light. ne represents the refractive index of the nematic liquid crystal molecules with respect to extraordinary light. λ represents the center wavelength of selective reflection.
In addition, as described in Japanese Patent Application No. 2004-352081, a photoreactive chiral compound having photosensitivity as a chiral compound and capable of greatly changing the helical pitch of liquid crystal by light is used. It is preferable to use a filter for an optical recording medium in which the helical pitch is continuously changed in the thickness direction of the liquid crystal layer by adjusting the compound content and the UV irradiation time.

In the case of a plurality of cholesteric liquid crystal layers, it is preferable to stack cholesteric liquid crystal layers having different selective reflection center wavelengths and having the same rotational direction of the spirals of the cholesteric liquid crystal layers.
The cholesteric liquid crystal layer is not particularly limited as long as it satisfies the above characteristics, and can be appropriately selected according to the purpose.As described above, the cholesteric liquid crystal layer contains a nematic liquid crystal compound and a chiral compound. Further, it contains other components as required.

-Nematic liquid crystal compounds-
The nematic liquid crystal compound is characterized in that the liquid crystal phase is fixed below the liquid crystal transition temperature, and the refractive index anisotropy Δn is 0.10 to 0.40, a liquid crystal compound, a polymer liquid crystal compound, and a polymerizability It can be appropriately selected from liquid crystal compounds according to the purpose. While it is in the liquid crystal state at the time of melting, it can be used as a solid phase by, for example, aligning by using an alignment substrate subjected to alignment treatment such as rubbing, and then cooling and fixing as it is.

  The nematic liquid crystal compound is not particularly limited and may be appropriately selected depending on the purpose. From the viewpoint of ensuring sufficient curability, a nematic liquid crystal compound having a polymerizable group in the molecule is preferable, and among these, Ultraviolet (UV) polymerizable liquid crystals are preferred. Commercially available products can be used as the UV polymerizable liquid crystal, for example, trade name PALIOCOLOR LC242 manufactured by BASF; trade name E7 manufactured by Merck; trade name LC-Slicon-CC3767 manufactured by Wacker-Chem; Takasago Examples include trade names L35, L42, L55, L59, L63, L79, and L83 manufactured by Perfume Co., Ltd.

  As content of the said nematic liquid crystal compound, 30-99 mass% is preferable with respect to the total solid content mass of each said cholesteric liquid crystal layer, and 50-99 mass% is more preferable. When the content is less than 30% by mass, the alignment of the nematic liquid crystal compound may be insufficient.

-Chiral compounds-
The chiral compound is not particularly limited in the case of a multi-layer cholesteric liquid crystal layer, and can be appropriately selected from known ones according to the purpose. From the viewpoint of improving the hue and color purity of the liquid crystal compound, , Isomannide compounds, catechin compounds, isosorbide compounds, fencon compounds, carboxylic compounds, and the like. These may be used alone or in combination of two or more.
Moreover, a commercial item can be used as said chiral compound, As this commercial item, the brand name S101, R811, CB15 by Merck, and the brand name PALIOCOLOR LC756 by BASF are mentioned, for example.

  The chiral compound content in each liquid crystal layer of the multi-layer cholesteric liquid crystal layer is preferably 0 to 30% by mass and more preferably 0 to 20% by mass with respect to the total solid mass of each cholesteric liquid crystal layer. When the content exceeds 30% by mass, the orientation of the cholesteric liquid crystal layer may be insufficient.

-Polymerizable monomer-
In the cholesteric liquid crystal layer, for example, a polymerizable monomer can be used in combination for the purpose of improving the degree of curing such as film strength. When the polymerizable monomer is used in combination, after changing the twisting force of the liquid crystal by light irradiation (patterning) (for example, after forming a selective reflection wavelength distribution), the helical structure (selective reflectivity) is fixed, The strength of the cholesteric liquid crystal layer after fixation can be further improved. However, when the liquid crystal compound has a polymerizable group in the same molecule, it is not necessarily added.
The polymerizable monomer is not particularly limited and may be appropriately selected from known ones according to the purpose. Examples thereof include monomers having an ethylenically unsaturated bond, and specifically, pentaerythritol. And polyfunctional monomers such as tetraacrylate and dipentaerythritol hexaacrylate. These may be used alone or in combination of two or more.
As addition amount of the said polymerizable monomer, 0-50 mass% is preferable with respect to the total solid content mass of the said cholesteric liquid crystal layer, and 1-20 mass% is more preferable. When the addition amount exceeds 50% by mass, the orientation of the cholesteric liquid crystal layer may be inhibited.

-Other ingredients-
The other components are not particularly limited and may be appropriately selected depending on the purpose. For example, photopolymerization initiator, sensitizer, binder resin, polymerization inhibitor, solvent, surfactant, thickener , Dyes, pigments, ultraviolet absorbers, gelling agents and the like.

There is no restriction | limiting in particular as said photoinitiator, According to the objective, it can select suitably according to the objective, For example, p-methoxyphenyl-2,4-bis (trichloromethyl) -s-triazine, 2- (p-butoxystyryl) -5-trichloromethyl 1,3,4-oxadiazole, 9-phenylacridine, 9,10-dimethylbenzphenazine, benzophenone / Michler's ketone, hexaarylbiimidazole / mercaptobenzimidazole, benzyl Examples include dimethyl ketal, acylphosphine derivatives, and thioxanthone / amine. These may be used alone or in combination of two or more.
As the photopolymerization initiator, commercially available products can be used. Examples of the commercially available products include trade names of Irgacure 907, Irgacure 369, Irgacure 784, and Irgacure 814 manufactured by Ciba Specialty Chemicals; Examples include lucillin TPO.

  The addition amount of the photopolymerization initiator is preferably 0.1 to 20% by mass, and more preferably 0.5 to 5% by mass with respect to the total solid mass of the cholesteric liquid crystal layer. When the addition amount is less than 0.1% by mass, it may take a long time because the curing efficiency at the time of light irradiation is low, and when it exceeds 20% by mass, the light transmittance from the ultraviolet region to the visible light region is increased. May be inferior.

The sensitizer can be used as necessary and is added to increase the degree of cure of the cholesteric liquid crystal layer.
There is no restriction | limiting in particular as said sensitizer, According to the objective, it can select suitably according to the objective, For example, diethyl thioxanthone, isopropyl thioxanthone, etc. are mentioned.
The addition amount of the sensitizer is preferably 0.001 to 1.0 mass% with respect to the total solid mass of the cholesteric liquid crystal layer.

There is no restriction | limiting in particular as said binder resin, According to the objective, it can select suitably according to the objective, For example, Polyvinyl alcohol; Polystyrene compounds, such as a polystyrene and poly-alpha-methylstyrene; Methylcellulose, ethylcellulose, acetyl Cellulose resins such as cellulose; acidic cellulose derivatives having a carboxyl group in the side chain; acetal resins such as polyvinyl formal and polyvinyl butyral; methacrylic acid copolymer, acrylic acid copolymer, itaconic acid copolymer, crotonic acid copolymer Examples thereof include a polymer, a maleic acid copolymer, a partially esterified maleic acid copolymer; a homopolymer of acrylic acid alkyl ester or a homopolymer of alkyl methacrylic acid; other polymer having a hydroxyl group. These may be used alone or in combination of two or more.
Examples of the alkyl group in the homopolymer of acrylic acid alkyl ester or homopolymer of methacrylic acid alkyl ester include, for example, methyl group, ethyl group, n-propyl group, n-butyl group, iso-butyl group, and n-hexyl group. , A cyclohexyl group, a 2-ethylhexyl group, and the like.
Examples of the other polymer having a hydroxyl group include benzyl (meth) acrylate / (homopolymer of methacrylic acid) acrylic acid copolymer, benzyl (meth) acrylate / (meth) acrylic acid / multiple monomers of other monomers. A polymer etc. are mentioned.

  As addition amount of the said binder resin, 0-80 mass% is preferable with respect to the total solid mass of the said cholesteric liquid crystal layer, and 0-50 mass% is more preferable. When the addition amount exceeds 80% by mass, the orientation of the cholesteric liquid crystal layer may be insufficient.

There is no restriction | limiting in particular as said polymerization inhibitor, According to the objective, it can select suitably, For example, hydroquinone, hydroquinone monomethyl ether, phenothiazine, benzoquinone, or these derivatives etc. are mentioned.
As addition amount of the said polymerization inhibitor, 0-10 mass% is preferable with respect to solid content of the said polymerizable monomer, and 100 ppm-1 mass% is more preferable.

  The solvent is not particularly limited and may be appropriately selected from known solvents according to the purpose. For example, 3-methoxypropionic acid methyl ester, 3-methoxypropionic acid ethyl ester, 3-methoxypropionic acid propyl Esters, alkoxypropionic acid esters such as 3-ethoxypropionic acid methyl ester, 3-ethoxypropionic acid ethyl ester, 3-ethoxypropionic acid propyl ester; 2-methoxypropyl acetate, 2-ethoxypropyl acetate, 3-methoxybutyl acetate Esters of alkoxy alcohols such as: Lactic acid esters such as methyl lactate and ethyl lactate; Ketones such as methyl ethyl ketone, cyclohexanone and methylcyclohexanone; γ-butyrolactone, N-methylpyrrolidone, di Sulfoxide, chloroform, tetrahydrofuran, and the like. These may be used alone or in combination of two or more.

As a method for forming the cholesteric liquid crystal layer, for example, a coating solution for a cholesteric liquid crystal layer prepared using the solvent (in the case of a plurality of layers, a coating solution for each cholesteric liquid crystal layer) is applied onto the substrate and dried. For example, a cholesteric liquid crystal layer can be formed by irradiating with ultraviolet rays.
The most suitable method for mass production is to prepare the base material in a roll form, and apply a coating solution for the cholesteric liquid crystal layer on the base material such as bar coat, die coat, blade coat, curtain coat, etc. A type in which coating is performed with a long continuous coater is preferable.

Examples of the coating method include spin coating, casting, roll coating, flow coating, printing, dip coating, casting film formation, bar coating, and gravure printing.
There is no restriction | limiting in particular as conditions for the said ultraviolet irradiation, According to the objective, it can select suitably, For example, 160-380 nm is preferable and, as for irradiation ultraviolet rays, 250-380 nm is more preferable. For example, the irradiation time is preferably 0.1 to 600 seconds, and more preferably 0.3 to 300 seconds. By adjusting the conditions of ultraviolet irradiation, the helical pitch in the optical cholesteric liquid crystal layer using the reactive chiral agent can be continuously changed along the thickness direction of the liquid crystal layer.

  In order to adjust the conditions of the ultraviolet irradiation, an ultraviolet absorber may be added to the cholesteric liquid crystal layer. There is no restriction | limiting in particular as this ultraviolet absorber, According to the objective, it can select suitably, For example, a benzophenone type ultraviolet absorber, a benzotriazole type ultraviolet absorber, a salicylic acid type ultraviolet absorber, a cyanoacrylate type ultraviolet absorber Preferable examples include oxalic acid anilide-based ultraviolet absorbers. Specific examples of these ultraviolet absorbers include JP-A Nos. 47-10537, 58-111942, 58-212844, 59-19945, 59-46646, 59. No. -109055, No. 63-53544, No. 36-10466, No. 42-26187, No. 48-30492, No. 48-31255, No. 48-41572, No. 48. -54965, 50-10726, U.S. Pat. Nos. 2,719,086, 3,707,375, 3,754,919, 4, No. 220,711 and the like.

In the case of the plural layers, the thickness of each cholesteric liquid crystal layer is preferably, for example, 1 to 10 μm, and more preferably 2 to 7 μm. When the thickness is less than 1 μm, the selective reflectance is not sufficient, and when it exceeds 10 μm, the uniform alignment of the liquid crystal layer may be disturbed.
Further, the total thickness of each cholesteric liquid crystal layer (in the case of a single layer, the thickness of the cholesteric liquid crystal layer) is, for example, preferably 1 to 30 μm, and more preferably 3 to 10 μm.

<Method for producing filter for optical recording medium having cholesteric liquid crystal layer>
There is no restriction | limiting in particular as a manufacturing method of the said filter for optical recording media, According to the objective, it can select suitably.
The optical recording medium filter is not particularly limited and may be appropriately selected depending on the purpose. However, the entire base material is processed into a disk shape (for example, punching processing), and is applied to the second substrate of the optical recording medium. Is preferably arranged. Moreover, when using for the filter layer of an optical recording medium, it can also provide directly on a 2nd board | substrate not via a base material.

<Base material>
There is no restriction | limiting in particular as said base material, According to the objective, it can select suitably, For example, what was synthesize | combined suitably may be used and a commercial item may be used.
There is no restriction | limiting in particular as thickness of the said base material, According to the objective, it can select suitably, 10-500 micrometers is preferable and 50-300 micrometers is more preferable. When the thickness of the base material is less than 10 μm, the adhesion may be lowered due to the bending of the substrate. On the other hand, if it exceeds 500 μm, the focal positions of the information light and the reference light must be greatly shifted, and the optical system size becomes large. For laminating the wavelength selective films, known adhesives can be used in any combination.
There is no restriction | limiting in particular as said adhesive, According to the objective, it can select suitably, For example, a rubber adhesive, an acrylic adhesive, a silicone adhesive, a urethane adhesive, a vinyl alkyl ether adhesive , Polyvinyl alcohol pressure sensitive adhesive, polyvinyl pyrrolidone pressure sensitive adhesive, polyacrylamide pressure sensitive adhesive, and cellulose pressure sensitive adhesive.
The application thickness of the adhesive or the pressure-sensitive adhesive is not particularly limited and can be appropriately selected according to the purpose. From the viewpoint of optical properties and thinning, 0.1 to 10 μm is preferable in the case of an adhesive, 0.1-5 micrometers is more preferable. Moreover, in the case of an adhesive, 1-50 micrometers is preferable and 2-30 micrometers is more preferable.

<Gap layer lamination process>
There is no restriction | limiting in particular as said gap layer lamination process, According to the objective, it can select suitably, For example, the 1st gap layer type | system | group process of forming a 1st gap layer between a 2nd board | substrate and a filter layer. And a second gap layer forming step of forming a second gap layer between the filter layer and the recording layer.

-First gap layer formation process-
The first gap layer forming step is a step of forming a first gap layer between the filter layer and the reflective film as necessary, and is formed for the purpose of smoothing the surface of the second substrate. It is also effective for adjusting the size of the hologram generated in the recording layer. That is, since it is necessary for the recording layer to form an interference region for recording reference light and information light to a certain size, it is effective to provide a gap between the recording layer and the servo pit pattern.
The first gap layer can be formed, for example, by applying a material such as an ultraviolet curable resin on the servo pit pattern by spin coating or the like and curing it. Moreover, when using what apply | coated and formed on the transparent base material as a filter layer, this transparent base material will work | function also as a 1st gap layer.
There is no restriction | limiting in particular as thickness of said 1st gap layer, According to the objective, it can select suitably, 1-200 micrometers is preferable.

-Second gap layer forming step-
The second gap layer forming step is a step of forming a second gap layer between the recording layer and the filter layer as necessary.
There is no restriction | limiting in particular as a material of said 2nd gap layer, According to the objective, it can select suitably, For example, a triacetyl cellulose (TAC), a polycarbonate (PC), a polyethylene terephthalate (PET), polystyrene (PS) ), Transparent resin films such as polysulfone (PSF), polyvinyl alcohol (PVA), polymethyl methacrylate = polymethyl methacrylate (PMMA), etc., or JSR brand name ARTON film or Nippon Zeon brand name ZEONOR And norbornene-based resin films. Among these, those having high isotropic properties are preferred, and TAC, PC, trade name ARTON, and trade name ZEONOR are particularly preferred.
There is no restriction | limiting in particular as thickness of said 2nd gap layer, According to the objective, it can select suitably, 1-200 micrometers is preferable.

<Laminated body formation process>
The laminated body forming step includes the recording layer, the filter layer, the first gap layer, and the second layer forming step, the filter layer forming step, the first gap layer forming step, and the second gap layer forming step. This is a process including a second substrate on which a two-gap layer is formed and the first substrate to form a laminate, and including other processes appropriately selected as necessary.
The bonding method is not particularly limited and can be appropriately selected according to the purpose.For example, the first substrate, the second substrate, and other layers appropriately selected as necessary, Examples thereof include a method of bonding with an adhesive, a method of pressure bonding without using an adhesive, and a method of bonding in a vacuum.
The method for bonding with the adhesive is not particularly limited and may be appropriately selected depending on the purpose. For example, the first substrate, the second substrate, and other appropriately selected as necessary These layers are bonded to each other at 23 to 100 ° C. by matching the outer circumference, applying an adhesive between the layers, and applying a pressure of 0.01 to 0.5 MPa from the outside.
In the bonding, it is preferable that the bonding is performed in a vacuum so that there is no bubble and the film is uniformly adhered.

-Adhesive-
There is no restriction | limiting in particular as said adhesive agent, According to the objective, it can select suitably, For example, an acrylic adhesive, an epoxy-type adhesive agent, a rubber-type adhesive agent etc. are mentioned.
Among these, acrylic adhesives and epoxy adhesives are more preferable because of excellent transparency.

  The method of performing pressure bonding without using the adhesive can also be used to form a laminated body by using the adhesiveness of each layer for adhesion. The first substrate, the second substrate, and other layers appropriately selected as needed are matched with each outer periphery, and a pressure of 0.01 to 0.5 MPa is applied from the outside to Adhere at 100 ° C. In order to adhere without any bubbles during the adhesion, it is preferable to bond them in a vacuum.

<Through hole formation process>
The through-hole forming step is a step of processing an inner hole at the center of the laminated body obtained by the laminated body forming step of the optical recording medium of the present invention.
The inner hole is processed so that the central axis thereof coincides with the central axis in the rotation direction of the servo track formed on the second substrate. If the center axis of the inner hole is deviated from the center axis of the servo track, the optical recording medium is shaken in the radial direction when the optical recording medium is mounted on an optical recording / reproducing apparatus and rotated. The track cannot be tracked due to light or the like, which may cause a track detection error.
The method for matching the central axes is not particularly limited and may be appropriately selected depending on the purpose. For example, as shown in FIG. 1, a servo track formed on a disk-shaped laminate 19 is used. The positions of at least three points 32a, 32b, and 32c on the outermost circumference of the laminate 19 are measured, and the processing center 32 of the circle of the laminate 19 is obtained based on the measurement points. The method of obtaining the processing center 32 is not particularly limited and may be appropriately selected depending on the purpose. For example, as shown in FIG. 2, a triangle connecting P, Q, and R with outer peripheral points is formed, If a straight line perpendicular to the center of PQ is drawn and an intersection of a straight line perpendicular to the center of QR is O, the point O can be obtained as the center of the laminate 19. Further, as shown in FIG. 9, if the center mark 38 is formed at the center portion in the rotation direction of the servo track formed on the second substrate 1, it is not necessary to separately obtain the processing center 32 and it is efficient. Can be processed.
The center mark 38 is not particularly limited and may be appropriately selected depending on the purpose. For example, the center mark 38 is sufficiently larger than the diameter of a recess having a diameter of 0.1 to 3.0 mm, a + -line mark, and a predetermined inner hole. And a small through hole for a guide. Since the center mark 32 serves as a guide for drilling, it is preferably formed on the outer surface of the laminate.

There is no restriction | limiting in particular as a drilling method, According to the objective, it can select suitably, For example, punch press processing, drill processing, laser processing, ultrasonic processing etc. are mentioned.
Specifically, as shown in FIG. 3, punch press processing in which a punch having a diameter substantially the same as that of the inner hole 25 is punched by a press at the center of the laminate 19 in the direction of the arrow, or laser or Laser processing, ultrasonic processing, etc. that irradiate ultrasonic waves and process an inner hole of a predetermined diameter can be mentioned. Moreover, as shown in FIG. 4, it can drill by rotating either the laminated body 19 or the drilling drill 35. As shown in FIG. As the drilling method, as shown in FIG. 5, a drill having a diameter corresponding to the guide through-hole formed using a small guide through-hole formed at the center of the laminate 19 and having a relatively thin tip portion. For example, drilling using a stepped drill 36 having two types of diameters of a drill having a predetermined diameter may be used.

  There is no restriction | limiting in particular as a diameter of the inner hole of the said optical recording medium, According to the objective, it can select suitably, For example, 10-20 mm is preferable and 15.00-15.15 mm is more preferable. If the diameter is less than 10 mm, the rotational holding ability of the recording medium may be reduced, and if it exceeds 20 mm, the recording area of the recording medium may be narrowed and the storage capacity may be reduced.

  It is preferable that the central axis of the inner hole of the optical recording medium and the central axis in the rotation direction of the servo track formed in the laminated body coincide with each other, but at least the amount of deviation between the central axes, that is, the deviation. The core amount is preferably 0 to 70 μm. If the amount of eccentricity exceeds 70 μm, the track may not be detected during tracking servo with servo light.

-Measuring method of eccentricity of inner hole of optical recording medium-
The method for measuring the eccentricity of the inner hole of the optical recording medium is not particularly limited and can be appropriately selected according to the purpose. For example, as shown in FIG. 6, the inner hole 43 of the optical recording medium 21 is rotated. When the optical recording medium 21 is rotated by being mounted on the spindle 46, the optical recording medium rotates around the central axis 42 of the inner hole of the optical recording medium. On the other hand, the servo light 44 is applied to the optical recording medium 21, and the servo light 44 is transmitted through the objective lens 12 so as to be condensed on the surface of the servo track 47, thereby operating the autofocus. The tracking servo of the servo light 44 is not operated and is fixed at a certain radial position of the optical recording medium. When the optical recording medium 21 is rotated in such a state, the eccentric servo track traverses the laser beam of the servo light 44, so that a tracking error signal is output every time one track is traversed. When the optical recording medium 21 makes one rotation (360 degrees), the light traverses the eccentric track and returns to the same place again. One half of the value obtained by multiplying the number of peaks of the tracking error signal during that time by the track pitch (the distance between tracks in the radial direction of the optical recording medium) is the eccentricity.

<Other processes>
There is no restriction | limiting in particular as said other process, According to the objective, it can select suitably, For example, a reflective film formation process etc. are mentioned.

-Reflective film formation process-
The reflective film forming step is a step of forming a reflective film on the servo pit pattern surface of the second substrate.
As the material of the reflective film, a material having a high reflectance with respect to recording light or reference light is preferably used. When the wavelength of light to be used is 400 to 780 nm, for example, Al, Al alloy, Ag, Ag alloy, etc. are preferably used. When the wavelength of light to be used is 650 nm or more, it is preferable to use Al, Al alloy, Ag, Ag alloy, Au, Cu alloy, TiN, or the like.
As the reflective film, an optical recording medium that reflects light and can be written or erased, such as a DVD (digital video disk), is used. It is also possible to add and rewrite directory information such as information on which part has an error and how replacement processing is performed without affecting the hologram.

There is no restriction | limiting in particular as a formation method of the said reflecting film, According to the objective, it can select suitably, Various vapor phase growth methods, for example, a vacuum evaporation method, sputtering method, plasma CVD method, photo-CVD method, ion plate method. A ting method, an electron beam evaporation method, or the like is used. Among these, the sputtering method is excellent in terms of mass productivity and film quality.
The thickness of the reflective film is preferably 50 nm or more, and more preferably 100 nm or more so that sufficient reflectance can be realized.

<Optical recording medium>
The optical recording medium of the present invention may be a relatively thin planar hologram for recording information such as two dimensions, or a volume hologram for recording a large amount of information such as a three-dimensional image, and is either a transmission type or a reflection type. Also good. The hologram recording method may be any, for example, an amplitude hologram, a phase hologram, a blazed hologram, a complex amplitude hologram, or the like.
The optical recording medium of the present invention includes a recording layer formed on at least one support, and a two-beam interference method used for recording a general hologram in which information light and reference light are irradiated from different directions. A first substrate, a second substrate, a recording layer on the second substrate, and a filter layer between the second substrate and the recording layer. Examples thereof include those used in a collinear method in which irradiation is performed such that the optical axis of the information light and the optical axis of the reference light are coaxial. An optical recording medium used in the collinear method will be described below, but the present invention is not limited to this method, and a two-beam interference method may be used.

<Optical recording method and reproducing method>
As the optical recording method, the optical recording medium is irradiated with information light and reference light as a coaxial light beam, and information is recorded on a recording layer by an interference pattern due to interference between the information light and the reference light. The method etc. are mentioned.
The reproduction method is not particularly limited and can be appropriately selected depending on the purpose. For example, the interference image formed on the recording layer by the optical recording method is irradiated with the same light as the reference light. Recording information corresponding to can be reproduced.

In the optical recording method and the reproducing method, the information light provided with a two-dimensional intensity distribution and the information light and the reference light having a substantially constant intensity are superposed inside the photosensitive recording layer to form them. Information is recorded by generating an optical characteristic distribution inside the recording layer using the interference pattern. On the other hand, when reading (reproducing) written information, the recording layer is irradiated with only the reference light in the same arrangement as during recording, and the reproduction has an intensity distribution corresponding to the optical characteristic distribution formed inside the recording layer. Light is emitted from the recording layer as light.
Here, the optical recording method and the reproducing method are performed using an optical recording / reproducing apparatus described below.

An optical recording / reproducing apparatus used in the optical recording method and reproducing method will be described with reference to FIG.
FIG. 16 is an overall configuration diagram of the optical recording / reproducing apparatus. The optical recording / reproducing apparatus includes an optical recording apparatus and a reproducing apparatus.
The optical recording / reproducing apparatus 100 controls a spindle 81 to which the optical recording medium 21 is attached, a spindle motor 82 for rotating the spindle 81, and the spindle motor 82 so as to keep the rotational speed of the optical recording medium 21 at a predetermined value. A spindle servo circuit 83.
The optical recording / reproducing apparatus 100 records information by irradiating the optical recording medium 21 with information light and recording reference light, and irradiates the optical recording medium 21 with reproduction reference light for reproduction. A pickup 31 for detecting light and reproducing information recorded on the optical recording medium 21, and a drive device 84 that can move the pickup 31 in the radial direction of the optical recording medium 21 are provided.

  The optical recording / reproducing apparatus 100 uses a detection circuit 85 for detecting a focus error signal FE, a tracking error signal TE, and a reproduction signal RF from an output signal of the pickup 31, and a focus error signal FE detected by the detection circuit 85. Based on this, the actuator in the pickup 31 is driven to move the objective lens (not shown) in the thickness direction of the optical recording medium 21 to perform focus servo, and the tracking error signal detected by the detection circuit 85. Based on TE, a tracking servo circuit 87 that drives an actuator in the pickup 31 to move the objective lens in the radial direction of the optical recording medium 21 to perform tracking servo, a tracking error signal TE, and a command from a controller to be described later. Drive 84 controlled by a and a slide servo circuit 88 for performing a slide servo for moving the pickup 31 in the radial direction of the optical recording medium 21.

The optical recording / reproducing apparatus 100 further decodes output data of a later-described CMOS or CCD array in the pickup 31 to reproduce data recorded in the data area of the optical recording medium 21 or reproduce from the detection circuit 85. A signal processing circuit 89 that reproduces a basic clock from the signal RF and discriminates an address, a controller 90 that controls the entire optical recording / reproducing apparatus 100, and an operation unit 91 that gives various instructions to the controller 90. And has.
The controller 90 inputs the basic clock and address information output from the signal processing circuit 89, and controls the pickup 31, spindle servo circuit 83, slide servo circuit 88, and the like. The spindle servo circuit 83 receives the basic clock output from the signal processing circuit 89. The controller 90 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory), and the CPU executes a program stored in the ROM using the RAM as a work area. The function of the controller 90 is realized.

  Specific examples 1 and 2 of the optical recording medium having the reflective film, the first and second gap layers of the present invention will be described in more detail with reference to the drawings. Note that an optical recording medium may be manufactured without laminating one or both of the first and second gap layers.

<Specific example 1 of optical recording medium>
FIG. 12 is a schematic cross-sectional view showing the configuration of the optical recording medium in Example 1 of the present invention. In the optical recording medium 21 according to the specific example 1, the servo pit pattern 3 is formed on the second substrate 1 made of polycarbonate resin or glass, and the servo pit pattern 3 is coated with aluminum, gold, platinum, etc. 2 is provided. In FIG. 12, the servo pit pattern 3 is formed on the entire surface of the second substrate 1, but it may be formed periodically as shown in FIG. The height of the servo pit pattern 3 is normally 1,750 mm (175 nm), which is sufficiently smaller than the thicknesses of the substrate and other layers.

The first gap layer 8 is formed by applying a material such as an ultraviolet curable resin on the reflective film 2 of the second substrate 1 by spin coating or the like. The first gap layer 8 is effective for protecting the reflective film 2 and adjusting the size of the hologram generated in the recording layer 4. That is, since it is necessary to form an interference area between the recording reference light and the information light in a certain size in the recording layer 4, it is effective to provide a gap between the recording layer 4 and the servo pit pattern 3.
A filter layer 6 is provided on the first gap layer 8, and a second gap layer 7 is provided between the filter layer 6 and the recording layer 4, and the filter layer 6 and the first substrate 5 (polycarbonate resin). The optical recording medium 21 is configured by sandwiching the second gap layer and the recording layer 4 by a substrate or a glass substrate. Note that there is a point where the information light and the reproduction light are focused. However, if the focusing area is filled with a photopolymer, excessive consumption of the monomer due to overexposure occurs, resulting in a decrease in multiplex recording capability. Therefore, it is effective to provide the second gap layer 7 that is non-reactive and transparent.

In FIG. 12, the filter layer 6 transmits only red light and does not transmit light of other colors. Therefore, since the information light, the recording and reproduction reference light are green or blue light, the light does not pass through the filter layer 6 and does not reach the reflection film 2 but becomes return light and is emitted from the incident / exit surface A. Become.
The filter layer 6 is composed of three cholesteric liquid crystal layers 6a, 6b, and 6c whose spiral pitch continuously changes in the thickness direction of the liquid crystal layer. The filter layer 6 made of this cholesteric liquid crystal layer may be directly formed on the first gap layer 8 by coating, or a film in which a cholesteric liquid crystal layer is formed on a substrate is punched into an optical recording medium shape and arranged. Also good. Λ _{0 to} λ ₀ / cos 20 °, especially λ _{0 to} λ ₀ / cos 40 ° (in particular, λ ₀ is the wavelength of the irradiation light) by the three cholesteric liquid crystal layers whose spiral pitch continuously changes in the thickness direction of the liquid crystal layer. In this case, the light reflectance is 40% or more, and the selective reflection wavelength does not shift even if the incident angle changes.

  The optical recording medium 21 in the specific example 1 may have a disk shape as shown in FIG. 7 or a card shape. In the case of a card shape, there is no need for the servo pit pattern. In this optical recording medium 21, the second substrate 1 is 0.6 mm, the first gap layer 8 is 100 μm, the filter layer 6 is 2 to 3 μm, the second gap layer 7 is 70 μm, and the recording layer 4 is 0.6 mm. The first substrate 5 has a thickness of 0.6 mm, and the total thickness is about 1.9 mm.

Next, an optical operation around the optical recording medium 21 will be described with reference to FIG. First, light (red light) emitted from the servo laser is reflected almost 100% by the dichroic mirror 13 and passes through the objective lens 12. Servo light is applied to the optical recording medium 21 by the objective lens 12 so as to be focused on the reflective film 2. That is, the dichroic mirror 13 transmits light having a wavelength of green or blue, and reflects light having a wavelength of red by almost 100%. The servo light incident from the light incident / exit surface A of the optical recording medium 21 passes through the first substrate 5, the recording layer 4, the second gap layer 7, the filter layer 6, and the first gap layer 8, and is reflected. The light is reflected by the film 2, passes through the first gap layer 8, the filter layer 6, the second gap layer 7, the recording layer 4, and the first substrate 5 and is emitted from the incident / exit surface A again. The returned return light passes through the objective lens 12, is reflected almost 100% by the dichroic mirror 13, and servo information is detected by a servo information detector (not shown). The detected servo information is used for focus servo, tracking servo, slide servo, and the like. Since the hologram material constituting the recording layer 4 is not sensitive to red light, even if the servo light passes through the recording layer 4 or the servo light is irregularly reflected by the reflective film 2, the recording layer 4 is not affected. In addition, since the return light of the servo light reflected by the reflective film 2 is reflected almost 100% by the dichroic mirror 13, the servo light is detected by the CMOS sensor or the CCD 14 for detecting the reproduced image. In addition, there is no noise with respect to the reproduction light.
Note that the reflection range of λ _{0 to} 1.3λ ₀ shown in FIG. 14 is 1.3λ ₀ = 692 nm when λ ₀ = 532 nm, and the servo light is reflected when the servo light is 655 nm. The range of λ _{0 to} 1.3λ ₀ shown here is suitability for ± 40 ° incident light in the filter layer, but when actually using such a large oblique light, servo light with an incident angle within ± 20 ° is used. Servo control can be performed without hindrance if masked. If the spiral pitch of the cholesteric liquid crystal layer in the filter layer to be used is sufficiently large, it is easy to design all the incident angles within ± 20 ° in the filter layer, in which case λ _{0 to} 1.1λ. _{Since a zero} cholesteric liquid crystal layer is sufficient, there is no hindrance to servo light transmission.

  In addition, the information light and the recording reference light generated from the recording / reproducing laser pass through the polarizing plate 16 to become linearly polarized light, pass through the half mirror 17 and pass through the quarter-wave plate 15 at a time. Become polarized. The optical recording medium 21 is irradiated with information light and recording reference light through the dichroic mirror 13 so as to generate an interference pattern in the recording layer 4 by the objective lens 12. The information light and the recording reference light are incident from the incident / exit surface A and interfere with each other in the recording layer 4 to generate an interference pattern there. Thereafter, the information light and the recording reference light pass through the recording layer 4 and enter the filter layer 6, but are reflected between the bottom of the filter layer 6 and become return light. That is, the information light and the recording reference light do not reach the reflective film 2. This is because the filter layer 6 is formed of three cholesteric liquid crystal layers whose spiral pitch continuously changes in the thickness direction of the liquid crystal layer, and has a property of transmitting only red light. Alternatively, if light leaking through the filter layer is suppressed to 20% or less of the incident light intensity, even if the leaked light reaches the bottom surface and becomes return light, it is reflected again by the filter layer and reproduced. The light intensity mixed into the light is 20% × 20% = 4% or less, which is not substantially a problem.

<Specific example 2 of optical recording medium>
FIG. 13 is a schematic cross-sectional view showing the configuration of the optical recording medium in the second specific example. The optical recording medium 22 according to Example 2 is configured in the same manner as Example 1 except for the filter layer 6.

In FIG. 13, the filter layer 6 transmits only red light and does not transmit light of other colors. Therefore, since the information light, the recording and reproduction reference light are green or blue light, the light does not pass through the filter layer 6 and does not reach the reflection film 2 but becomes return light and is emitted from the incident / exit surface A. Become.
The filter layer 6 is a laminate in which a dielectric vapor deposition layer is formed by laminating seven dielectric thin films having different refractive indexes on a color material-containing layer. The filter layer 6 that is a combination of the color material-containing layer and the dielectric vapor-deposited film may be directly formed on the first gap layer 8 by coating and vapor deposition, or may be formed on the base material. The film on which the deposited film is formed may be punched into an optical recording medium shape and disposed. By using a combination of a colorant-containing layer and a dielectric deposited film as a filter layer, the light transmittance at 655 nm is 50% or more and the light reflectance at 532 nm is 30% at an incident angle of ± 40 °. Thus, even if the incident angle changes, the selective reflection wavelength does not shift.

  The shape of the optical recording medium 22 in the specific example 2 may be a disk shape or a card shape, and is formed in the same manner as the specific example 1.

  Next, an optical operation around the optical recording medium 22 configured in the same manner as the optical recording medium 21 will be described with reference to FIG. In the optical recording medium 22, as in the optical recording medium 21, first, light (red light) emitted from the servo laser is reflected almost 100% by the dichroic mirror 13 and passes through the objective lens 12. Servo light is applied to the optical recording medium 22 by the objective lens 12 so as to be focused on the reflective film 2. That is, the dichroic mirror 13 transmits light having a wavelength of green or blue, and reflects light having a wavelength of red almost 100%. The servo light incident from the light incident / exit surface A of the optical recording medium 22 passes through the first substrate 5, the recording layer 4, the second gap layer 7, the filter layer 6, and the first gap layer 8 and is reflected. The light is reflected by the film 2, passes through the first gap layer 8, the filter layer 6, the second gap layer 7, the recording layer 4, and the first substrate 5 and is emitted from the incident / exit surface A again. The returned return light passes through the objective lens 12, is reflected almost 100% by the dichroic mirror 13, and servo information is detected by a servo information detector (not shown). The detected servo information is used for focus servo, tracking servo, slide servo, and the like. As in the first specific example, the hologram material constituting the recording layer 4 is not sensitive to red light, so that the servo light passes through the recording layer 4 or the servo light is reflected by the reflective film 2. Even if it is irregularly reflected, the recording layer 4 is not affected. In addition, since the return light of the servo light reflected by the reflective film 2 is reflected almost 100% by the dichroic mirror 13, the servo light is detected by the CMOS sensor or the CCD 14 for detecting the reproduced image. In addition, there is no noise with respect to the reproduction light.

  In addition, the information light and the recording reference light generated from the recording / reproducing laser pass through the polarizing plate 16 to become linearly polarized light, pass through the half mirror 17 and pass through the quarter-wave plate 15 at a time. Become polarized. The optical recording medium 22 is irradiated with information light and recording reference light through the dichroic mirror 13 so as to generate an interference pattern in the recording layer 4 by the objective lens 12. The information light and the recording reference light are incident from the incident / exit surface A and interfere with each other in the recording layer 4 to generate an interference pattern there. Thereafter, the information light and the recording reference light pass through the recording layer 4 and enter the filter layer 6, but are reflected between the bottom of the filter layer 6 and become return light. That is, the information light and the recording reference light do not reach the reflective film 2. This is because the filter layer 6 is a combination of a color material-containing layer and a dielectric deposited film, and has a property of transmitting only red light. Alternatively, if light leaking through the filter layer is suppressed to 20% or less of the incident light intensity, even if the leaked light reaches the bottom surface and becomes return light, it is reflected again by the filter layer and reproduced. The light intensity mixed into the light is 20% × 20% = 4% or less, which is not substantially a problem.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

Example 1
<Preparation of optical recording medium>
The optical recording medium of Example 1 is formed by laminating a first substrate, a recording layer, a second gap layer, a filter layer, a first gap layer, and a second substrate in this order. It produced as follows. The filter layer was formed as follows by preparing and laminating a film-like filter.

-Composition of photosensitive composition solution for recording layer-
The photosensitive composition which consists of the following composition was mixed under nitrogen stream, and the photosensitive composition solution was prepared.
-----------------------------------
・ Biscyclohexylmethane diisocyanate ・ ・ ・ 31.5 mass%
-Polypropylene oxide triol (molecular weight 1,000)-61.2% by mass
・ Tetramethylene glycol ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 2.5% by mass
-2,4,6-tribromophenyl acrylate ... 3.1% by mass
Photopolymerization initiator (Ciba Specialty Chemicals, Irgacure 784) 0.69% by mass
・ Dibutyl dilaurate tin ・ ・ ・ 1.01% by mass
-----------------------------------

-Fabrication of filter-
First, a base film is prepared by applying polyvinyl alcohol (trade name MP203, manufactured by Kuraray Co., Ltd.) to a thickness of 1 μm on a polycarbonate film (trade name: Iupil, manufactured by Mitsubishi Gas Chemical Co., Inc.) having a thickness of 100 μm. This base film can be passed through a rubbing apparatus to rub the surface of the polyvinyl alcohol film and impart liquid crystal alignment ability.

  Next, cholesteric liquid crystal layer coating liquids A, B, and C having the compositions shown in Table 1 below can be prepared by a conventional method.

＊ＵＶ重合性液晶：ＢＡＳＦ社製、商品名ＰＡＬＩＯＣＯＬＯＲ ＬＣ２４２
＊カイラル剤：ＢＡＳＦ社製、商品名ＰＡＬＩＯＣＯＬＯＲ ＬＣ７５６
＊光重合開始剤：チバスペシャルティケミカルズ社製、商品名イルガキュア３６９
＊増感剤：ジエチルチオキサントン
＊溶剤：メチルエチルケトン（ＭＥＫ）

* UV polymerizable liquid crystal: manufactured by BASF, trade name PALIOCOLOR LC242
* Chiral agent: BASF Corporation, trade name PALIOCOLOR LC756
* Photopolymerization initiator: Product name Irgacure 369, manufactured by Ciba Specialty Chemicals
* Sensitizer: Diethylthioxanthone * Solvent: Methyl ethyl ketone (MEK)

Next, the cholesteric liquid crystal layer coating solution A was applied onto the base film with a bar coater, dried, and then subjected to orientation aging at 110 ° C. for 20 seconds. Thereafter, the film was exposed to an irradiation energy of 500 mJ / cm ² with an ultrahigh pressure mercury lamp at 110 ° C. to form a cured cholesteric liquid crystal layer A having a thickness of 2 μm.
Next, the cholesteric liquid crystal layer coating solution B was applied onto the cholesteric liquid crystal layer A with a bar coater, dried, and then subjected to alignment aging at 110 ° C. for 20 seconds. Then, it exposed by irradiation energy 500mJ / cm < ² > with the ultrahigh pressure mercury lamp under 110 degreeC, and the cholesteric liquid crystal layer cured film B with a thickness of 2 micrometers was formed.
Next, the cholesteric liquid crystal layer coating liquid C was applied onto the cholesteric liquid crystal layer B with a bar coater, dried, and then subjected to alignment aging at 110 ° C. for 20 seconds. Thereafter, exposure was performed at an irradiation energy of 500 mJ / cm ² with an ultrahigh pressure mercury lamp at 110 ° C. to form a cured cholesteric liquid crystal layer C having a thickness of 2 μm.
As described above, Embodiment 1 of a three-layer structure having circularly polarized light separation characteristics, different selective reflection center wavelengths in each cholesteric liquid crystal layer, and the same rotational direction of the spiral in each cholesteric liquid crystal layer in the clockwise direction. An optical recording medium filter was prepared.

  Next, the produced optical recording medium filter was punched into a predetermined disk size so that it could be placed on the substrate.

-First substrate-
As the first substrate, a polycarbonate resin plate having a diameter of 120 mm and a plate thickness of 0.5 mm was used. The surface of this substrate is smooth and has no irregularities such as a servo pit pattern.

-Second substrate-
As the second substrate, a general polycarbonate resin substrate used for DVD + RW having a diameter of 120 mm and a plate thickness of 0.6 mm was used. A servo pit pattern is formed on the entire surface of the substrate, the track pitch is 0.74 μm, the groove depth is 175 nm, and the groove width is 300 nm.
First, a reflection film was formed on the surface of the servo pit pattern of the second substrate so that the reflectance by incident light perpendicular to the light having a wavelength of 532 nm was 90%. Aluminum (Al) was used as the reflective film material. A 200 nm thick Al reflective film was formed by DC magnetron sputtering.

-Outer spacer-
The outer peripheral spacer has a circular shape with a diameter of 120 mm, which is the same as the outer shape of the first substrate and the second substrate, the width in the surface direction is 0.5 mm ± 100 μm, and the thickness is 500 μm, which is the same as the thickness of the recording layer 4. The cross-sectional shape is a square of 0.5 mm × 500 μm.
The material of the outer periphery spacer was produced by injection molding (manufactured by Sumitomo Heavy Industries, Ltd.) using polycarbonate having excellent moldability and mechanical strength.

-Formation of laminate-
As shown in FIG. 8, on the second substrate 1 on which the first gap layer 8 has been spin-coated, the filter is placed on a UV adhesive (model name SD-640, Dainippon, Japan) so that air bubbles do not enter the gap. After applying the ink), the filter layer 6 was formed by laminating.
On the surface of the filter layer 6, a thickness of 500 μm under the conditions of a pressure roll temperature of 23 ° C., a pressure roll pressure of 0.1 MPa, and a pressure speed of 1.0 m / min by a laminator device (model name HAL110aa, manufactured by Sankyo Co., Ltd.) A second gap layer 7 made of a transparent polyethylene terephthalate sheet was attached.
Further, the obtained outer peripheral spacer 27 was adhered to the surface of the second gap layer 7 so that the outer shape of the second substrate 1 and the outer shape of the outer peripheral spacer 27 matched. The adhesive was bonded by irradiating UV light using a UV adhesive (model name SD-640, manufactured by Dainippon Ink & Chemicals, Inc.).
The composition coating solution for an optical recording layer obtained by the injection method was injected into a groove portion formed by the outer peripheral spacer 27 with a depth of 500 μm by a syringe.
The injection conditions were a temperature of 23 ° C., a liquid viscosity of 300 mPas, and a humidity of 50%.
After the injection, the optical recording layer composition was cured under the conditions of a temperature of 80 ° C. for 40 minutes to form a recording layer 4. The recording layer 4 had a thickness of 500 μm.
On the recording layer 4, an adhesive (type name GM-9002, manufactured by Brennie Giken) was applied, and the outside of the first substrate and the outside of the second substrate were applied at a pressure of 0.08 MPa, and 80 The laminate was formed by pressurizing at 40 ° C. for 40 minutes, and finally the end was sealed with a moisture-curing adhesive and left at 45 ° C. for 24 hours.

-Drilling of laminates-
In the drilling of the laminate, first, as shown in FIG. 1, three measurement points on the outermost periphery of the servo track provided in the laminate 19 were measured. Then, as shown in FIG. 2, a triangle connecting P, Q, and R with the outer peripheral points is formed, a straight line that intersects perpendicularly with the center of PQ is drawn, and an intersection of a straight line that intersects perpendicularly with the center of QR is defined as O Then, the O point was set as the center of the laminate 19. Specifically, when the horizontal line in contact with the lower part in FIG. 2 of the laminate 19 is represented as the X axis, the vertical line in contact with the left side in FIG. 2 as the Y axis, and expressed as coordinates (X, Y), the coordinates of 32a are: The coordinates of (57.832, 71.460), 32b are (137.345, -4.401), the coordinates of 32c are (166.8336, 71.460), and the coordinates of the center O are (112 334, 51.623).
The position of the obtained center O is marked in a + shape, and the laminate 19 is mounted on a laser precision cutting device (model name: LAY-753A, manufactured by Shibaura Mechatronics), and the position of the center O is A through hole having a diameter of 15.1 mm was processed in accordance with the center to obtain an inner hole of the optical recording medium.

-Measurement of eccentricity of inner hole of optical recording medium-
The measurement of the eccentricity of the inner hole of the optical recording medium is performed using a high-precision measurement microscope apparatus (model name: HyperMF-U, manufactured by Mitutoyo Corporation) and the central axis of the servo track formed on the optical recording medium The amount of eccentricity of the central axis of the inner hole was measured. As a result, the amount of eccentricity was about 9 μm, which could be suppressed to 10 μm or less with respect to the amount of eccentricity of about 100 μm generated by the conventional manufacturing method, and an optical recording medium with very little eccentricity was obtained.
Furthermore, in the conventional method for producing an optical recording medium by laminating perforated substrates, an optical recording composition such as a photopolymer protrudes from the inner wall surface of the inner hole, thereby impairing the uniformity of the inner wall surface of the inner hole. However, the method for producing an optical recording medium of the present invention has no such problem at all, and the productivity and the quality of the optical recording medium are greatly improved.

-Recording and evaluation of optical recording media-
Using the collinear hologram recording / reproduction tester SHOT-1000, manufactured by Pulstec Industrial Co., Ltd., the obtained optical recording medium is used to write a series of multiple holograms with a recording spot size of 200 μm in diameter at the focal position of the recording hologram. The sensitivity (recording energy) and multiplex number were measured and evaluated.

-Measurement of sensitivity-
The irradiation light power (mJ / cm ² ) at the time of recording was changed, and the change in the error probability (BER: Bit Error Rate) of the reproduction signal was measured. Normally, the BER of a reproduction signal tends to gradually decrease as the reproduction signal luminance increases with an increase in recording light power. Here, the recording power of the recording material is defined as the lowest recording light power at which a substantially good reproduced image (BER <10 ⁻³ ) can be obtained. As a result, BER <10 ⁻³ was obtained at a recording sensitivity recording light power of 150 mJ / cm ² . (Recording sensitivity 75 mJ / cm ² )

-Evaluation of multiple numbers-
As a multiple evaluation method for optical recording media, ISOM'04, Th-J-06, pp. 184-185, Oct. The recording spot described in 2004 was shifted by a spiral and evaluated. Here, the number of recorded holograms was 13 × 13 = 169 holograms, and the recording pitch was 28.5 μm. The multiplicity when recording the last 169th hologram is 49. Since the multiplicity increases as the number of recording holograms increases, if the recording material has insufficient multiplexing characteristics, the BER increases as the number of recordings increases. Here, the number of recording holograms that gives BER> 10 ⁻³ is defined as the multi-characteristic M of the material. It was confirmed that a characteristic equivalent to 169 multiplexing was obtained as the multiplexing characteristic M by this method.

-Productivity evaluation-
The above-mentioned productivity enables effective use of people, goods and equipment at the production site, and is effective for production lines aiming at 100% work efficiency with less equipment investment and less work in progress (short production lead time). The results of a comprehensive evaluation of whether or not it is appropriate, the degree of yield, the uniformity of quality, etc., and the stage evaluation based on the following criteria, the productivity of the present invention may be effective over conventional manufacturing methods all right.

  According to the method for producing an optical recording medium of the present invention, the step of matching the center position of the inner hole at the time of assembling the laminate of the optical recording medium, and the optical recording composition does not protrude from the inner wall surface of the inner hole. Is processed after the laminated body is formed, so that the occurrence of center misalignment of the inner hole at the time of assembling the optical recording medium is reduced, and there is no center shift during reproduction, and good tracking servo can be performed. Is obtained. It is widely used in manufacturing methods for relatively thin planar holograms for recording information such as two dimensions, volume holograms for recording large amounts of information such as stereoscopic images, and reflection holograms.

FIG. 1 is a conceptual diagram showing an arbitrary point measurement on the outer periphery of the laminate of the optical recording medium of the present invention. FIG. 2 is an explanatory diagram of an example in which the center is obtained from the points on the outer periphery of the laminate of the optical recording medium of the present invention. FIG. 3 is a perspective view showing drilling by the laser cutting method of the optical recording medium of the present invention. FIG. 4 is a conceptual diagram showing the processing of the inner hole by the drilling drill for the laminated body of the optical recording medium of the present invention. FIG. 5 is a conceptual diagram showing processing of an inner hole by a stepped drilling drill for the optical recording medium laminate of the present invention. FIG. 6 is an explanatory diagram showing an example of a method for measuring the track runout of the optical recording medium of the present invention. FIG. 7 is a partial cross-sectional view of an example of the optical recording medium of the present invention. FIG. 8 is an exploded perspective view of the laminated body of the optical recording medium of the present invention. FIG. 9 is a perspective view showing an example of a center mark of a substrate having servo tracks of the optical recording medium of the present invention. FIG. 10 is an exploded perspective view of a conventional laminated body of optical recording media. FIG. 11 is a schematic sectional view showing the structure of a conventional optical recording medium. FIG. 12 is a schematic cross-sectional view showing an example of an optical recording medium according to Example 1 according to the present invention. FIG. 13 is a schematic cross-sectional view showing an example of an optical recording medium according to Example 2 according to the present invention. FIG. 14 is a graph showing reflection characteristics with respect to incident light from the front (0 °) of a filter in which three cholesteric liquid crystal layers are laminated. FIG. 15 is an explanatory diagram showing an example of an optical system around the optical recording medium according to the present invention. FIG. 16 is a block diagram showing an example of the overall configuration of the optical recording / reproducing apparatus of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 2nd board | substrate 1a Inner hole 2 Reflective film 3 Servo pit pattern 4 Recording layer 5 1st board | substrate 5a Inner hole 6 Filter layer 6a, 6b, 6c Cholesteric liquid crystal layer 7 Second gap layer 8 First gap layer 12 Objective lens DESCRIPTION OF SYMBOLS 13 Dichroic mirror 14 Detector 15 1/4 wavelength plate 16 Polarizing plate 17 Half mirror 19 Laminated body 19a Processing waste 20, 21, 22 Optical recording medium 25 Inner hole 26 Center small hole 27 Outer periphery spacer 31 Pickup 32 Processing center 32a, 32b, 32c Peripheral point 35 Drilling hole 36 Stepped drilling hole 38 Center mark 39 Servo track 42 Inner hole center axis 43 Inner hole 44 Servo light 45 Servo track center axis 46 Rotating spindle 47 Servo track 81 Spindle 82 Spindle motor 83 Spindle Bo circuit 84 drive device 85 detection circuit 86 a focus servo circuit 87 a tracking servo circuit 88 Slide servo circuit 89 signal processing circuit 90 Controller 91 Operation unit 100 optical recording and reproducing apparatus A entry and exit surface FE Focus error signal TE Tracking error signal RF reproduced signal

Claims (6)

A laminate forming step of forming a disk-like laminate by laminating a recording layer for recording information using holography between the first substrate and the second substrate, and a filter layer;
A through hole forming step of forming a through hole so that a central axis in a rotation direction of a servo track provided in the laminated body coincides with a central axis of the through hole when the through hole is formed in the laminated body. A method for producing an optical recording medium.   The center mark that is formed on the surface of at least one of the first substrate and the second substrate and that indicates the position of the central axis in the rotation direction of the servo track provided in the laminate coincides with the central axis of the through hole. The method of manufacturing an optical recording medium according to claim 1, wherein the through-hole is formed as described above.   Measure at least three points on the outermost servo track provided in the laminate, determine a central axis in the rotation direction of the servo track based on the measurement points, and determine the central axis and the central axis of the through hole The method for manufacturing an optical recording medium according to claim 1, wherein the through holes are formed so that the two coincide with each other.   An optical recording medium manufactured by the method for manufacturing an optical recording medium according to claim 1.   The optical recording medium according to claim 4, further comprising: a first substrate; a second substrate; and a recording layer and a filter layer between the first substrate and the second substrate. 6. An optical recording in which irradiation of information light and reference light onto the optical recording medium according to claim 4 is performed such that the optical axis of the information light and the optical axis of the reference light are coaxial. An optical recording medium used in the method.

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