JP2007041087A - Optical element, polarized plane light source using the same and display apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical element or the like which can output emission light stimulated by incident light with high efficiency as linearly polarized light having a prescribed vibration plane. <P>SOLUTION: The optical element 100 has a luminous light transmission body 10 formed to a plate shape by comprising a light-transmissive resin 1, minute area portions 2 which are dispersed and distributed in the light-transmissive resin and have birefringence different from that of the light-transmissive resin and a luminous material 3 which is contained in the light-transmissive resin and/or in the minute area portions and which can output emission light stimulated by incident light from the outside. Rugged structure 20 having a ramp 201 inclined to a flat face when vertically cross-sectionally viewed is formed on at least one among facing flat faces 101, 102 of the luminous light transmission body. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical element, a polarization plane light source using the optical element, and a display device using the optical element, and in particular, can efficiently emit light excited and emitted through incident light as linearly polarized light having a predetermined vibration surface. The present invention relates to an optical element, a polarization plane light source using the same, and a display device using the same.

  The liquid crystal display device needs to make polarized light incident on the liquid crystal cell in principle. For this reason, conventionally, a configuration in which polarized light is obtained by disposing a polarizer on the exit surface side of the backlight and the polarized light is incident on the liquid crystal cell has been exclusively employed. However, as long as an absorptive polarizer (a polarizer that absorbs one of S-polarized light and P-polarized light and transmits the other polarized light using iodine or a dichroic dye) is used as a polarizer, for example. The utilization efficiency of the light emitted from the light has to be 50% or less.

  For this reason, a circularly polarized light separating film made of cholesteric liquid crystal (see Patent Document 1) or a linearly polarized light separating film made of a multilayer thin film having refractive index anisotropy (see Patent Document 2) is formed on the light exit surface side of the backlight. By using the absorption polarizer, there has been a proposal that reuses polarized light in a direction lost as an absorption loss when using the above-described absorption polarizer, thereby increasing the light utilization efficiency.

  On the other hand, the light guide (the plate-like translucent material for guiding the light emitted from the light source) to the liquid crystal cell itself is provided with a fine prism structure to provide a polarization separation function. (See Patent Documents 3 and 4).

  However, when the polarization separating function is given to the light guide itself constituting the backlight, the intensity of light propagating inside the light guide is different between the vicinity of the light source and the distance from the light source. In order to emit light with uniform intensity, it is necessary to strictly design a pattern of a fine prism structure having a polarization separation function. For example, in order to make the intensity of the emitted polarized light uniform over the entire light exit surface of the light guide, the fine structure distribution is rough in the vicinity of the light source and the fine structure distribution is dense in the distance from the light source. It seems to be.

  The design of the prism structure as described above is extremely troublesome, and there is a problem that the compatibility of members necessary for forming the prism structure is poor. In other words, the prism structure must be designed individually according to the dimensions of the light guide and the arrangement of the light source (side light type, direct type). When manufacturing, it was necessary to prepare a mold individually according to the distribution state of the prism structure.

  Accordingly, in order to solve the above-described problems, the inventors of the present invention integrate the light guide and the luminescent material, and emit light excited and emitted through incident light from at least one of the front and back surfaces. An optical element that can be emitted as linearly polarized light having a predetermined vibration surface has been developed (see Patent Document 5).

However, in the optical element described in Patent Document 5, if the content of the minute region portion is increased to improve the degree of polarization of the linearly polarized light that is emitted and the scattering property in the minute region portion is increased, the optical element is confined within the optical element. As a result, the light output efficiency is reduced as a result, resulting in a decrease in light emission efficiency.
JP-A-9-304770 US Pat. No. 6,025,977 Japanese Patent Laid-Open No. 2005-50412 US Pat. No. 5,729,311 JP 2004-205953 A

  The present invention has been made to solve such problems of the prior art, and an optical element capable of emitting light excited and emitted via incident light as linearly polarized light having a predetermined vibration surface with high efficiency, and the optical element It is an object of the present invention to provide a polarization plane light source using a light source and a display device using the same.

  In order to solve the above-described problems, the present invention provides a translucent resin and a dispersion-distributed distribution of the translucent resin and the birefringent resin as described in claim 1. A light-emitting light guide formed in the shape of a plate comprising different micro-region portions and a light-emitting material that is contained in the translucent resin and / or the micro-region portion and is excited and emitted by light incident from the outside And an uneven structure having an inclined portion inclined with respect to the flat surface in a longitudinal sectional view is formed on at least one of the opposing flat surfaces of the light-emitting light guide. Is to provide.

  According to the first aspect of the present invention, the luminescent material is excited by light (excitation light) incident on the inside of the light emitting light guide from the side surface or the front and back surfaces, and the excited light is emitted from the light emitting light guide and the air. Is totally reflected at the air interface according to the difference in refractive index between the light and the light, and is transmitted within the light-emitting light guide. Of such transmitted light, a linearly polarized light component having a vibration plane parallel to the axial direction (Δn1 direction) of the minute region portion where the difference in refractive index between the minute region portion and the translucent resin has a maximum value (Δn1) is obtained. It will be selectively scattered strongly. Of such scattered light, light scattered at an angle smaller than the total reflection angle is emitted from the light-emitting light guide to the outside (air).

  On the other hand, the light scattered at an angle larger than the total reflection angle in the scattering in the Δn1 direction, the light that did not collide with the minute region portion, and the light having a vibration surface other than the Δn1 direction are confined in the light emitting light guide. The light is transmitted while repeating total reflection, and the polarization state is canceled by the birefringence phase difference in the light-emitting light guide, and satisfies the Δn1 direction condition (outputs as linearly polarized light having a vibration surface parallel to the Δn1 direction). Will wait for the opportunity to do.

  According to the first aspect of the present invention, the concavo-convex structure having the inclined portion that is inclined with respect to the flat surface in the longitudinal sectional view is formed on at least one of the opposing flat surfaces of the light-emitting light guide. The Thereby, even in the light satisfying the Δn1 direction condition, even if the light is scattered at an angle larger than the total reflection angle in relation to the flat surface, the total reflection condition is reached by reaching the inclined portion of the concavo-convex structure. Is broken (the angle formed by the scattered light and the inclined portion is smaller than the angle formed by the scattered light and the flat surface), and light is emitted to the outside. Accordingly, it is possible to emit linearly polarized light with high efficiency without excessively confining light within the light-emitting light guide.

  The “translucent resin” in the present invention means a resin having transparency with respect to wavelengths of at least light incident from the outside (excitation light) and light emitted from the luminescent material. In addition, as the “concave / convex structure having inclined portions” in the present invention, in addition to a structure in which a plurality of ridges having a triangular or trapezoidal longitudinal section are arranged, quadrangular pyramid-shaped convex portions are arranged in a matrix. The structure etc. can be illustrated.

  Here, if the inclination angle of the inclined portion is too small, the ratio of breaking the total reflection condition is reduced for light satisfying the Δn1 direction condition, whereas if the inclination angle of the inclined portion is too large, the backscattering is increased. There is a problem that the light utilization efficiency is lowered due to the decrease of the front emission light due to the increase of the confinement light due to the critical angle. Therefore, preferably, as described in claim 2 of the claims, the average inclination angle of the inclined portion is set to 30 ° or more and 60 ° or less. The “average inclination angle” in the present invention means a value obtained by dividing the sum of the angles formed by each inclined portion and the flat surface by the number of inclined portions.

  The concavo-convex structure is formed, for example, by applying a polymerizable resin to the flat surface of the light-emitting light guide and transferring the shape of the mold to the applied resin as described in claim 3. Is done.

  Alternatively, as described in claim 4 of the present invention, a concavo-convex structure comprising a concavo-convex structure formed by transferring the shape of a mold to a polymerizable resin and bonded to a flat surface of the light-emitting light guide. It is also possible to do. Note that when the light-emitting light guide and the concavo-convex structure are bonded together, it is necessary to bond the light-emitting light guide and the concavo-convex structure so that no gap exists between them. This is because when there is a gap between the two, a critical angle corresponding to the refractive index difference between the light-emitting light guide and the gap (refractive index = 1.0) is generated, and the light-emitting light guide is bonded to the concavo-convex structure. This is because light is totally reflected on the flat surface of the light and is trapped in the light-emitting light guide.

  Further, as described in claim 5 of the present invention, an uneven structure formed by applying a thermoplastic resin to the flat surface of the light-emitting light guide and transferring the shape of the mold to the applied resin. Good.

  Alternatively, as described in claim 6, a concavo-convex structure comprising a concavo-convex structure formed by transferring the shape of a mold to a thermoplastic resin and bonded to a flat surface of the light-emitting light guide. It is also possible to do. As described above, when the light emitting light guide and the concavo-convex structure are bonded together, it is necessary to bond them so that there is no gap between them.

  If the refractive index of the material constituting the concavo-convex structure is too smaller than the refractive index of the translucent resin, total reflection of light occurs at the interface between the concavo-convex structure and the light-emitting light guide (translucent resin), The light confined in the light emitting light guide is increased. Therefore, preferably, as described in claim 7 of the claims, the refractive index of the material constituting the concavo-convex structure is set to be equal to or higher than the refractive index of the translucent resin. With such a preferable configuration, total reflection of light does not occur at the interface between the concavo-convex structure and the light-emitting light guide (translucent resin), and light satisfying the Δn1 direction condition reaches the inclined portion.

  The uneven structure may be formed by transferring the shape of a mold onto the flat surface of the light-emitting light guide, as described in claim 8. That is, the shape of the mold can be transferred to a part of the light-emitting light guide by extrusion or cutting.

  Here, the distribution of light scattered in the minute region portion becomes narrower along the major axis direction of the minute region portion, and becomes wider along the direction orthogonal to the major axis direction of the minute region portion. The magnitude of the spread of the scattered light is determined by the difference in refractive index between the microregion and the translucent resin, the curvature of the interface between the microregion and the translucent resin, and the distribution density of the microregion. This is because that. And since the curvature of the said interface along the major axis direction of a micro area | region part is large, the force which is going to bend light is weak, and the spread of scattered light becomes narrow. On the other hand, since the curvature of the interface along the minor axis direction of the minute region is small, the force for bending the light is strong, and the spread of the scattered light becomes wide. For this reason, the ratio of the light that satisfies the total reflection condition at the interface between the light-emitting light guide and the air and is confined in the light-emitting light guide increases along the direction orthogonal to the major axis direction of the minute region portion. Therefore, in order to efficiently emit the light scattered in the direction orthogonal to the long axis direction of the minute region portion to the outside, as described in claim 9 of the scope of claims, substantially in the major axis direction of the minute region portion. It is preferable to have a concavo-convex structure including a plurality of ridges provided so as to extend in a matching direction and the inclined portion is inclined in a direction substantially orthogonal to the major axis direction of the minute region portion.

  The present invention provides a light having a wavelength capable of exciting the optical element according to any one of claims 1 to 9 and a luminescent material included in the optical element, as described in claim 10. It is provided as a polarization plane light source characterized by comprising an excitation light source that emits light.

  Furthermore, the present invention is also provided as a display device comprising the polarization plane light source according to claim 10 as described in claim 11.

  According to the present invention, light excited and emitted through incident light can be emitted with high efficiency as linearly polarized light having a predetermined vibration surface.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.
1A and 1B are schematic views showing a schematic configuration of an optical element according to an embodiment of the present invention. FIG. 1A is a longitudinal sectional view, and FIG. 1B is a perspective view. As shown in FIG. 1, an optical element 100 according to the present embodiment includes a translucent resin 1 and a minute region 2 that is distributed and distributed in the translucent resin 1 and has a different birefringence from the translucent resin 1. And contained in the translucent resin 1 and / or the minute region 2 (in FIG. 1, an example contained in both the translucent resin 1 and the minute region 2 is illustrated). The light-emitting light guide 10 is formed in a plate shape (film shape, sheet shape, or plate shape) including the luminescent material 3 that emits light by excitation. Then, at least one of the opposing flat surfaces 101 and 102 of the light-emitting light guide 10 (in FIG. 1, an example formed on the flat surface 101 is illustrated), the flat surface 101 in the longitudinal sectional view is illustrated. The concavo-convex structure 20 having the inclined portion 201 inclined with respect to the surface is formed.

  It is preferable that the luminescent material 3 is uniformly dissolved or dispersed in one or both of the translucent resin 1 and the minute region 2. Since it is not desirable that light is scattered by the luminescent material 3, it is more preferable that the material be soluble. Further, when the luminescent material 3 is dispersed, the dispersion size is preferably as small as possible from the viewpoint of suppressing unnecessary light scattering. For example, when the light-emitting light guide 10 is formed, the light-emitting material 3 is preliminarily blended with other additives as necessary in the material for forming the translucent resin 1 or the minute region 2. It can be dissolved or dispersed by an appropriate method, such as a method of keeping it.

  As the luminescent material 3, one or more suitable materials that absorb ultraviolet light or visible light and excite and emit light having a wavelength in the visible light region can be used, and there is no particular limitation. More specifically, a fluorescent material or a phosphorescent material made of an organic dye or an inorganic pigment that emits fluorescent light emitted from excited singlet, phosphorescent light emitted from triplet, or the like can be used.

  In the light-emitting light guide 10, for example, regions having different birefringence are formed by appropriately orienting one or two or more kinds of suitable materials having excellent transparency such as polymers and liquid crystals. It can be formed by an appropriate method such as a method for obtaining an oriented film by using the combination. As described above, since the light emitting material 3 is desirably dispersed in a small size, it is preferable that at least one of the combined materials is miscible with the light emitting material 3 to be dispersed.

  Examples of combinations of the materials include combinations of polymers and liquid crystals, combinations of isotropic polymers and anisotropic polymers, combinations of anisotropic polymers, and the like. In addition, from the viewpoint of dispersion distribution of the minute region 2, it is preferable to use a combination that is phase-separated, and the dispersion distribution can be controlled by the compatibility of the materials to be combined. For example, phase separation can be performed by an appropriate method such as a method of dissolving an incompatible material with a solvent or a method of mixing an incompatible material while being heated and melted.

  When the orientation treatment is performed by a stretching treatment using a combination of the above materials, a combination of polymers and liquid crystals and a combination of an isotropic polymer and an anisotropic polymer can be used together with an anisotropic polymer depending on an arbitrary stretching temperature and a stretching ratio. In combination, the target light-emitting light guide 10 can be formed by appropriately controlling the stretching conditions. The anisotropic polymer is classified as positive or negative based on the characteristics of the change in refractive index in the stretching direction, but in this embodiment, any positive or negative anisotropic polymer can be used, a combination of positive and negative, Both negative combinations and positive and negative combinations can be used.

  Examples of the polymers include ester polymers such as polyethylene terephthalate and polyethylene naphthalate, styrene polymers such as polystyrene and acrylonitrile / styrene copolymers (AS polymers), polyethylene, polypropylene, and cyclo or norbornene structures. Examples include polyolefins, olefin polymers such as ethylene / propylene copolymers, acrylic polymers such as polymethyl methacrylate, cellulose polymers such as cellulose diacetate and cellulose triacetate, and amide polymers such as nylon and aromatic polyamide.

  Also, carbonate polymer, vinyl chloride polymer, imide polymer, sulfone polymer, polyether sulfone, polyether ether ketone, polyphenylene sulfide, vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer, arylate polymer, Polyoxymethylene, silicone-based polymer, urethane-based polymer, ether-based polymer, vinyl acetate-based polymer, mixture of the above polymers, phenol-based, melamine-based, acrylic-based, urethane-based, urethane-acrylic-based, epoxy-based, silicone-based, etc. Examples of the transparent polymers include thermosetting or ultraviolet curable polymers.

  On the other hand, examples of the liquid crystals include a nematic phase and a smectic phase at room temperature or high temperature, such as cyanobiphenyl, cyanophenylcyclohexane, cyanophenyl ester, benzoic acid phenyl ester, phenylpyrimidine, and mixtures thereof. In addition to the low-molecular liquid crystal and the cross-linkable liquid crystal monomer, a liquid crystal polymer exhibiting a nematic phase or a smectic phase at room temperature or high temperature may be used. The crosslinkable liquid crystal monomer is usually subjected to an alignment treatment and then subjected to a crosslinking treatment by an appropriate method using heat, light, or the like to obtain a polymer.

  From the viewpoint of obtaining a light-emitting light guide 10 having excellent heat resistance and durability, a glass transition temperature is preferably 50 ° C. or higher, more preferably 80 ° C. or higher, particularly preferably 120 ° C. or higher, and a crosslinkable liquid crystal. It is preferable to use a combination with a monomer or a liquid crystal polymer. As the liquid crystal polymer, an appropriate one such as a main chain type or a side chain type can be used, and the type thereof is not particularly limited. The degree of polymerization of the liquid crystal polymer is preferably 8 or more from the viewpoints of the formability of the microregions 2 having excellent uniformity in particle size distribution, thermal stability, moldability to film, and ease of alignment treatment. It is preferable to use 10 or more, particularly preferably 15 to 5000.

  The light-emitting light guide 10 using the liquid crystal polymer is, for example, a mixture of one or more types of polymers and one or more types of liquid crystal polymers for forming the microregions 2. It can be formed by a method of forming a polymer film dispersed and contained in a state of occupying a minute region, performing an orientation treatment by an appropriate method, and forming a region having different birefringence.

  As described above, the optical element 100 according to this embodiment is inclined with respect to the flat surface 101 of the light-emitting light guide 10 with respect to the flat surface 101 in the longitudinal sectional view (preferably, the average inclination angle is 30 ° or more and 60 °. The concavo-convex structure 20 having the inclined portion 201 (set to be not more than °) is formed. As a result, among the light scattered by the minute region portion 2, even the light scattered at an angle larger than the total reflection angle in relation to the flat surface 101, reaches the inclined portion 201 of the concavo-convex structure 20 as a whole. The reflection condition is broken (the angle formed between the scattered light and the inclined portion 201 is smaller than the angle formed between the scattered light and the flat surface 101), and light is emitted to the outside. Therefore, the light confined in the light-emitting light guide 10 is not excessively increased, and linearly polarized light can be emitted with high efficiency.

  In particular, the concavo-convex structure 20 according to the present embodiment, as a preferred mode, extends in a direction substantially coincident with the major axis direction of the minute region 2 (Y direction in FIG. 1B), and the inclined portion 201 has a minute region. It is set as the structure which comprises the some protruding item | line provided so that it may incline in the direction (X direction of FIG.1 (b)) substantially orthogonal to 2 major axis directions. Thereby, even if the distribution of the light scattered in the direction orthogonal to the major axis direction of the minute region portion 2 covers a wide range, the scattered light can be efficiently emitted to the outside.

  As the concavo-convex structure 20, it is possible to adopt a concavo-convex structure formed by transferring the shape of a mold to a polymerizable resin and bonded to the flat surface 101 of the light-emitting light guide 10 via the adhesive layer 4. is there. Alternatively, it is also possible to adopt a concavo-convex structure formed by transferring the shape of a mold to a thermoplastic resin and bonded to the flat surface 101 of the light-emitting light guide 10. In any case, when the light-emitting light guide 10 and the concavo-convex structure are bonded, it is necessary to bond them so that there is no gap between them. This is because if there is a gap between the two, a critical angle corresponding to the difference in refractive index between the light-emitting light guide 10 and the gap (refractive index = 1.0) is generated, and the light-emitting light guide is formed by bonding the concavo-convex structure. This is because light is totally reflected by the flat surface 101 of the body 10 and is confined in the light emitting light guide 10.

  In addition, as said polymeric resin, resin hardened | cured by photopolymerization can be illustrated, for example. Photopolymerization is a polymerization method in which active molecules are generated by light to advance the polymerization, and includes radical polymerization that generates radicals and cationic polymerization that generates cations. Further, as the polymerizable resin, a resin curable by thermal polymerization may be used. Thermal polymerization is a polymerization method in which active molecules are generated by heat to advance the polymerization. This thermal polymerization includes radical polymerization that generates radicals and cationic polymerization that generates cations. Examples of the radical polymerization type (photopolymerization or thermal polymerization) polymerizable resin include urethane acrylate-based, epoxy acrylate-based, ester acrylate-based, and acrylate-based polymerizable resins. Examples of the cationic polymerization (photopolymerization or thermal polymerization) polymerizable resin include polymerizable resins such as epoxy-based, vinyl ether-based, and oxetane-based epoxy resins. Examples of the thermoplastic resin include alicyclic compounds such as PMMA (polymethyl methacrylate), PC (polycarbonate), and Arton / Zeonoa.

  Moreover, as the uneven structure according to the present invention, as shown in FIG. 2A, a polymerizable resin or a thermoplastic resin is applied to the flat surface 101 of the light-emitting light guide 10, and gold is applied to the applied resin. It is also possible to employ a concavo-convex structure 20A formed by transferring the shape of a mold.

  In addition, when the refractive index of the material which comprises the uneven structure 20 or 20A is too smaller than the refractive index of the translucent resin 2, the interface of the uneven structure 20 or 20A and the light emission light guide 10 (translucent resin 2). Thus, total reflection of light occurs, and the light confined in the light emitting light guide 10 increases. Therefore, the refractive index of the material constituting the concavo-convex structure 20 or 20A may be set to be equal to or higher than the refractive index of the translucent resin 2 (a material having a refractive index higher than that of the translucent resin 2 is selected). preferable. With such a preferable configuration, total reflection of light does not occur at the interface between the concavo-convex structure 20 or 20 </ b> A and the light-emitting light guide 10 (translucent resin 2), and the light scattered in the minute region 2 reaches the inclined portion 201. Will do.

  Furthermore, as the concavo-convex structure according to the present invention, as shown in FIG. 2B, a concavo-convex structure 20B formed by transferring the shape of a mold to the flat surface of the light-emitting light guide 10 can be used. . That is, it is also possible to employ a concavo-convex structure 20B formed by transferring the shape of a mold to a part of the light-emitting light guide 10 by extrusion or cutting.

  The optical element 100 according to the present embodiment can form a polarization plane light source by combining with an excitation light source that emits light having a wavelength capable of exciting the luminescent material 3 included in the optical element 100. The arrangement of the excitation light source and the optical element 100 is not particularly limited, but it is desirable that the excitation light is effectively incident on the optical element 100. From this point of view, the configuration in which the excitation light source is arranged on the side surface of the optical element 100, or the excitation light source is a surface light source such as an electroluminescence element, and the flat surface 102 of the optical element 100 is arranged on the upper part thereof. A configuration is preferable.

  The optical element 100 according to the present embodiment described above and the polarization plane light source to which the optical element 100 is applied can emit light as linearly polarized light from the optical element 100 using light incident from the excitation light source. It can be suitably used for various display devices that use linearly polarized light such as display devices.

  Hereinafter, the features of the present invention will be further clarified by showing examples and comparative examples.

<Example 1> (corresponding to the configuration of the optical element shown in FIG. 1)
(1) Preparation of light-emitting light guide 950 parts (parts by weight, same applies hereinafter) of norbornene-based resin (manufactured by JSR, Arton, glass transition temperature 182 ° C.), liquid crystal polymer represented by the following chemical formula (glass transition temperature 80 ° C. Film having a thickness of 100 μm by a casting method using a 20 wt% dichloromethane solution in which 50 parts of nematic liquid crystallizing temperature 100 to 290 ° C. and 2 parts of 3- (2-benzothiazolyl) -7-diethylaminocoumarin (coumarin 540) are dissolved. The film was stretched 3 times at 180 ° C. and then rapidly cooled to form a light-emitting light guide.

  The light-emitting light guide is a transparent film made of norbornene-based resin in which a liquid crystal polymer is dispersed in a domain shape having substantially the same shape in the state of being elongated in the stretching direction, and the refractive index difference Δn1 is 0.23. When the refractive index difference in the axial direction orthogonal to the Δn1 direction is Δn2 and Δn3, Δn2 and Δn3 were 0.029, respectively. In measuring the refractive index difference, the norbornene-based resin alone was stretched under the same conditions as described above, and the liquid crystal polymer alone was applied onto the alignment film and aligned and fixed. The refractive index was measured with a refractometer, and the difference between them was calculated as Δn1, Δn2, and Δn3. Coumarin was present in a form dissolved in norbornene resin. Further, when the average diameter of the minute region (the domain of the liquid crystal polymer) was measured by coloring based on the phase difference by observation with a polarizing microscope, the length in the Δn1 direction was about 5 μm.

(2) Production of concavo-convex structure MMA for metal mold processed by a ruling engine (a mold in which a plurality of concave grooves having a vertical cross section of 90 ° apex angle is formed with a pitch of 100 μm) (Methacrylic acid): AA (acrylic acid): TMPTA (trimethylolpropane triacrylate) = 4: 1: 1 A mixture of 5 parts of photoinitiator Irgacure 184 was applied to the mixture. By irradiating this with ultraviolet rays, a concavo-convex structure cured by polymerization (a concavo-convex structure in which a plurality of ridges having a vertical cross section of a triangular shape with an apex angle of 90 ° formed at a pitch of 100 μm) was produced.

(3) Production of optical element Nitto Denko's No. 1 surface of the light-emitting light guide and the flat surface side of the concavo-convex structure were formed. Bonding was performed using 7 adhesives to produce an optical element. In addition, when bonding both together, both were arrange | positioned so that the ridgeline (direction where a protruding line | wire extends) of a concavo-convex structure may correspond with the extending | stretching axis | shaft of a light-emitting light guide.

(4) Evaluation of optical characteristics The optical element of Example 1 produced as described above exhibits about 20% higher emission luminance and lowers polarization characteristics as compared with a light-emitting light guide having no uneven structure. I was not able to admit. In the measurement of emission luminance, Philips black light (20 W) was used as an excitation light source, and Topcon BM-7 was used as a luminance meter. The same applies to Example 2, Comparative Example, and Reference Example described later.

<Example 2> (corresponding to the configuration of the optical element shown in FIG. 1)
(1) Production of light-emitting light guide (A) Material for producing light-emitting light guide A liquid crystal polymer used in Example 1 as Arton G grade manufactured by JSR as a light-transmitting resin and as a material for producing a microscopic region Were used as light-emitting materials (organometallic complexes), respectively, as rare earth complex nanoparticles (particle diameter 2 to 4 nm) represented by the following chemical formula.

(B) Preparation of arton solution The above arton was dissolved in cyclopentanone to prepare a 25 wt% solution. Only 5 parts by weight of the liquid crystal polymer and 2 parts by weight of the organometallic complex were added to and mixed with 100 parts by weight of the solid content of the Arton solution. Mixing was performed at 6000 rpm × 20 minutes using a homomixer. The obtained mixture was allowed to stand for 24 hours while being kept at 35 ° C. to obtain a uniform arton solution without bubbles.

(C) Film formation The above arton solution was applied with a wet thickness of 1 mm using an applicator and dried while raising the temperature from 50 ° C to 140 ° C over 1 hour to obtain a dry substrate.

(D) Stretching The above dried base material was stretched 2.5 times at 170 ° C. and then rapidly cooled to prepare a light emitting light guide.

  The light-emitting light guide produced as described above had a refractive index difference Δn1 of 0.15, and Δn2 and Δn3 were each 0.01. In the measurement of the difference in refractive index, the Abbe refractive index for Arton alone was subjected to a stretching treatment under the same conditions as above, and the liquid crystal polymer was individually applied to the alignment film and fixed in orientation. The refractive index was measured by a meter, and the difference between them was calculated as Δn1, Δn2, and Δn3. The rare earth complex was present mainly dispersed in Arton. Further, when the average length of the minute region (liquid crystal polymer) was measured by coloring based on a phase difference by observation with a polarizing microscope, the length in the major axis direction was about 5 μm and the length in the minor axis direction was about 1.5 μm. there were.

(2) Production of concavo-convex structure A plurality of protrusions having a regular triangular cross-section of 20 μm on each side by transferring the shape to ZEONOR (thickness 0.5 mm) manufactured by Nippon Zeon using a precision die hot press. Strips were formed at a pitch of 100 μm to produce a concavo-convex structure. The precision mold has a plurality of concave grooves formed by precision engraving using a ruling engine.

(3) Production of optical element One surface of the light-emitting light guide and the flat surface side of the concavo-convex structure were bonded together using a photopolymerization adhesive NOA-60 manufactured by Norland. The application thickness of the adhesive was 10 μm. Then, an ultraviolet ray of 1 J / cm ² was irradiated from the concavo-convex structure side, the adhesive was cured, and an optical device was produced. In addition, when bonding both together, both were arrange | positioned so that the ridgeline (direction where a protruding line | wire extends) of a concavo-convex structure may correspond with the extending | stretching axis | shaft of a light-emitting light guide.

(4) Evaluation of optical characteristics The optical element of Example 2 produced as described above exhibits about 20% higher emission luminance and lowers polarization characteristics as compared with a light-emitting light guide having no uneven structure. I was not able to admit.

<Comparative example>
As a comparative example, an optical element consisting only of the light-emitting light guide of Example 1 was produced. The optical element of the comparative example showed about 20% lower emission luminance than the optical element of Example 1. The degree of polarization of the emitted light was not significantly different from Example 1.

<Reference example>
The light-emitting light guide and the concavo-convex structure of Example 1 are disposed and pasted so that the ridge line (the direction in which the ridges extend) of the concavo-convex structure forms an angle of 45 ° with respect to the extending axis of the light-emitting light guide. In addition, an optical element was produced. In the optical element of the reference example, although the light emission brightness which is not much different from that of the optical element of Example 1 was obtained, the degree of polarization decreased.

1A and 1B are schematic views showing a schematic configuration of an optical element according to an embodiment of the present invention. FIG. 1A is a longitudinal sectional view, and FIG. 1B is a perspective view. FIG. 2 is a schematic diagram (longitudinal sectional view) showing a schematic configuration of an optical element according to another embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Translucent resin 2 ... Micro area | region 3 ... Luminescent material 4 ... Adhesive layer 10 ... Light-emitting light guide 20 ... Uneven structure 100 ... Optical element 101, 102 ... Flat surface 201 ... Inclined part

Claims (11)

A translucent resin, a micro-region part distributed and distributed in the translucent resin and having different birefringence from the translucent resin, and the outer part contained in the translucent resin and / or the micro-region part A light-emitting light guide that is formed in a plate shape and includes a light-emitting material that is excited and emitted by light incident from
An optical element, wherein an uneven structure having an inclined portion inclined with respect to the flat surface in a longitudinal sectional view is formed on at least one of the opposing flat surfaces of the light-emitting light guide.   2. The optical element according to claim 1, wherein an average inclination angle of the inclined portion is set to 30 ° or more and 60 ° or less.   3. The uneven structure is formed by applying a polymerizable resin to a flat surface of the light-emitting light guide and transferring a shape of a mold to the applied resin. 4. Optical elements.   3. The uneven structure according to claim 1, wherein the uneven structure is formed by transferring a shape of a mold to a polymerizable resin, and includes an uneven structure bonded to a flat surface of the light-emitting light guide. Optical element.   The said concavo-convex structure is formed by applying a thermoplastic resin to the flat surface of the light-emitting light guide and transferring the shape of a mold to the applied resin. Optical elements.   3. The uneven structure according to claim 1, wherein the uneven structure is formed by transferring a shape of a mold to a thermoplastic resin and is formed of an uneven structure bonded to a flat surface of the light emitting light guide. Optical element.   7. The optical element according to claim 1, wherein a refractive index of a material constituting the concavo-convex structure is set to be equal to or higher than a refractive index of the translucent resin.   The optical element according to claim 1, wherein the concavo-convex structure is formed by transferring a shape of a mold onto a flat surface of the light-emitting light guide.   The concavo-convex structure extends in a direction substantially coinciding with the long axis direction of the minute region portion, and a plurality of protrusions provided so that the inclined portion is inclined in a direction substantially perpendicular to the long axis direction of the minute region portion. The optical element according to claim 1, further comprising a strip. An optical element according to any one of claims 1 to 9,
A polarization plane light source comprising: an excitation light source that emits light having a wavelength that can excite a light-emitting material included in the optical element.   A display device comprising the polarization plane light source according to claim 10.

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