JP2006251589A - Optical element, polarized plane light source using element, and display apparatus using light source - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical element that can output emission light stimulated by incident light, as linearly polarized light with a sufficient polarization degree through at least one of the top or back surfaces, that can be easily manufactured without causing appearance failure and that emits light with high color purity. <P>SOLUTION: The optical element 10 is molded into a plate comprising a light transmitting resin 1 and minute area portions 2 which are dispersed and distributed in the transparent resin 1 and have birefringence different from that of the light transmitting resin 1, wherein the light transmitting resin 1 and/or the minute area portions 2 include at least one kind or more of rare earth complex 3 which emits light when excitation energy is externally applied. <P>COPYRIGHT: (C)2006,JPO&NCIPI

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, linearly polarized light having a predetermined vibration surface from at least one of front and back surfaces of light excited and emitted through incident light. The present invention relates to an optical element that can emit light, a polarization plane light source using the same, and a display device using the same.

  Conventionally, as a sidelight type light guide plate used for a so-called backlight of a liquid crystal display device, a light emitting means comprising a reflective dot containing a high reflectance pigment such as titanium oxide or barium sulfate is provided on a translucent resin plate. It is known that the light transmitted by the total reflection in the resin plate is emitted from one of the front and back surfaces of the resin plate by scattering or the like through the light emitting means.

  However, since the light emitted from the light guide plate having the above-described structure is natural light that hardly exhibits polarization characteristics, it is necessary to convert the emitted light into linearly polarized light through a polarizing plate when displaying liquid crystal. Accordingly, there is a problem in that light use efficiency cannot exceed 50% because light absorption loss is caused by the polarizing plate.

  Therefore, in order to solve such problems, various types of light utilization efficiency improvements have been made using polarization separation means that obtains linearly polarized light by using a so-called Brewster angle or polarization conversion means that uses a phase difference plate. (For example, Patent Literature 1, Patent Literature 2, Patent Literature 3, Patent Literature 4, Patent Literature 5, Patent Literature 6, Patent Literature 7, Patent Literature 8, Patent Literature 9, Patent Literature 10). , Patent Document 11, Patent Document 12 and Patent Document 13).

  However, such a conventional backlight has a problem that it is not practical because it cannot obtain sufficient polarization and it is difficult to control the polarization direction.

  Therefore, in order to solve the above-described problems, the inventors of the present invention can emit light excited and emitted through incident light as linearly polarized light having a predetermined vibration surface from at least one of the front and back surfaces. At the same time, an optical element and the like whose polarization direction (vibration plane) can be arbitrarily controlled has been developed (see Patent Document 14).

However, Patent Document 14 discloses an example using a powder of tris (8-quinolinolato) aluminum (generally referred to as Alq3) as a light emitter, but the commercial product used in this example is disclosed. Alq3 available in the field has a problem that it is difficult to obtain bright color light emission because the wavelength band of the light emitted when excited is wide and the color purity of the emitted light is low. .
Japanese Patent Laid-Open No. 6-18873 JP-A-6-160840 JP-A-6-265892 JP-A-7-72475 JP 7-261122 A Japanese Patent Laid-Open No. 7-270792 JP 9-54556 A JP-A-9-105933 JP-A-9-138406 JP-A-9-152604 Japanese Patent Laid-Open No. 9-293406 Japanese Patent Laid-Open No. 9-326205 Japanese Patent Laid-Open No. 10-78581 JP 2004-205953 A

  The present invention has been made to solve such problems of the prior art, and can emit light excited and emitted through incident light as linearly polarized light having a sufficient degree of polarization from at least one of the front and back surfaces. It is an object of the present invention to provide an optical element that can be easily manufactured without appearance defects and can easily obtain light emission with high color purity, a polarization plane light source using the optical element, and a display device using the optical element.

  In order to solve the above-mentioned problems, the inventors of the present invention have made extensive studies, and as a result, a light-emitting material is excited and emitted by incident light by containing a rare earth complex as a light-emitting material in a light-transmitting resin and / or a microscopic region. Can be emitted as linearly polarized light having a sufficient degree of polarization and high color purity from at least one of the front and back surfaces, and can be easily produced without causing appearance defects, and the brightness of the emitted light can be easily increased. The inventors have found that a possible optical element can be obtained and completed the present invention.

  That is, according to the present invention, as described in claim 1 of the present invention, the translucent resin is dispersed in the translucent resin, and the microregion is different in birefringence from the translucent resin. And at least one rare earth complex that emits light when excitation energy is applied from the outside in the translucent resin and / or the microregion part. An optical element is provided.

  According to the first aspect of the present invention, there is no need to provide a special light emitting means made of reflective dots or the like in the translucent resin as in the prior art, and the inside of the optical element (rare earth complex serving as a light emitter) by incident excitation light ) Can be emitted to the outside as linearly polarized light having a narrow wavelength band, high color purity, and a predetermined vibration surface. Further, the polarization direction (vibration plane) of linearly polarized light can be arbitrarily set according to the installation angle of the optical element (depending on which Δn1 direction described later is set).

  More specifically, most of the light excited by the rare earth complex by the excitation light incident on the inside of the optical element from the side surface or the front and back surfaces is entirely at the air interface according to the refractive index difference between the optical element and air. Reflected and transmitted in the optical element. 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, the light scattered at an angle smaller than the total reflection angle is emitted from the optical element to the outside (air).

  Here, considering the case where minute regions are not distributed and distributed in the translucent resin, the selective polarization scattering as described above does not occur. Therefore, the light excited and emitted by the rare earth complex in the optical element is three-dimensional. About 80% is confined in the translucent resin and repeats total reflection due to the angle.

  According to the first aspect of the present invention, the confined light is emitted to the outside of the optical element only when the total reflection condition is broken due to scattering at the interface between the minute region and the translucent resin. Therefore, it is possible to arbitrarily control the emission efficiency according to the size and distribution rate of the minute region.

  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 optical element. Opportunity to be transmitted while repeating total reflection, the polarization state is canceled due to the birefringence phase difference in the optical element, etc., and satisfy the Δn1 direction condition (to become linearly polarized light having a vibration surface parallel to the Δn1 direction) Will wait. By repeating the above operation, as a result, linearly polarized light having a predetermined vibration surface is efficiently emitted from the optical element.

  In addition, rare earth complexes have a narrow emission wavelength band and high durability, and can withstand long-term use. Therefore, optical properties superior in color purity, durability, and reliability compared to dye-based light emitters are used. It is possible to obtain an element.

  As described above, according to the first aspect of the invention, light excited and emitted through incident light can be emitted as linearly polarized light having a sufficient degree of polarization and high color purity from at least one of the front and back surfaces. It is easy to produce without appearance defects, and the brightness of the emitted light can be easily increased.

  Preferably, as described in claim 2 of the claims, the rare earth complex is a phosphor that absorbs ultraviolet light or visible light as the excitation energy and emits visible light.

  Preferably, the minute region is formed of a liquid crystalline material, a glassy material in which a liquid crystal phase is cooled and fixed, or a material in which a liquid crystal phase of polymerizable liquid crystal is cross-linked and fixed by energy rays.

  Or the said micro area part consists of a liquid crystal polymer whose glass transition temperature is 50 degreeC or more, and is comprised so that a nematic liquid crystal phase may be exhibited at temperature lower than the glass transition temperature of the said translucent resin.

Preferably, regarding the refractive index difference between the minute region portion and the translucent resin, the refractive index difference in the axial direction of the minute region portion at which the refractive index difference shows the maximum value is Δn1, and the maximum value is When the refractive index difference in the axial direction orthogonal to the axial direction shown is Δn2 and Δn3,
0.03 ≦ Δn1 ≦ 0.5
0 ≦ Δn2 ≦ 0.03
0 ≦ Δn3 ≦ 0.03
It is said.

  Further, the present invention emits light having a wavelength capable of exciting the optical element according to claim 1 or 2 and the rare earth complex contained in the optical element, as described in claim 3. The present invention is also provided as a polarization plane light source comprising an excitation light source.

  Preferably, the polarization plane light source further includes a light guide formed of a translucent material for guiding light emitted from the excitation light source to the optical element.

  The excitation light source can be composed of, for example, an inorganic or organic electroluminescence element or a mercury-free fluorescent tube.

  Furthermore, the present invention is also provided as a display device comprising the polarization plane light source according to claim 3 as described in claim 4.

  According to the present invention, light excited and emitted through incident light can be emitted from at least one of the front and back surfaces as linearly polarized light having a sufficient degree of polarization and high color purity, and without causing appearance defects. It is easy and the luminance of the emitted light can be easily increased.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a longitudinal sectional view showing a schematic configuration of an optical element according to an embodiment of the present invention. As shown in FIG. 1, an optical element 10 according to this embodiment includes a translucent resin 1 and a minute region portion that is dispersed and distributed in the translucent resin 1 and has a birefringence different from that of the translucent resin 1. 2 and is formed in a plate shape. Further, the optical element 10 contains (dissolves or disperses) at least one or more rare earth complexes 3 that emit light when excitation energy is applied from the outside in the translucent resin 1 and / or the minute region 2. ing. 1A shows an example in which the rare earth complex 3 is contained in the translucent resin 1, and FIG. 1B shows an example in which the rare earth complex 3 is contained in the minute region 2. 1 (c) shows an example in which the rare earth complex 3 is contained in both the translucent resin 1 and the minute region 2, but the optical element 10 according to this embodiment is shown in FIGS. ).

  The shape of the optical element 10 is not particularly limited as long as it has at least two opposing flat surfaces. From the viewpoint of use as a surface light source and total reflection efficiency, the shape of the optical element 10 is rectangular as shown in FIG. It is preferably a film shape, a sheet shape, or a plate shape. In particular, it is desirable to form the film shape in terms of easy handling.

  The thickness of the optical element 10 is preferably 20 μm to 3 mm, more preferably 30 μm to 1 mm, still more preferably 40 μm to 500 μm, and particularly preferably 50 μm to 200 μm. When the thickness of the optical element 10 is smaller than 20 μm, the excitation light emitted from the excitation light source may be transmitted as it is or the scattering property at the minute region 2 may be impaired, thereby causing uneven brightness. Moreover, since the transmission path of the scattered light in the minute region 2 cannot be sufficiently secured, there is a possibility that linearly polarized light having a sufficient degree of polarization cannot be obtained. On the other hand, when the thickness of the optical element 10 is thicker than 3 mm, the excitation light is not sufficiently transmitted in the thickness direction of the optical element 10, and it becomes impossible to effectively use all of the contained rare earth complex 3. There is a possibility that the luminous efficiency may be lowered. Therefore, it is preferable to set the thickness as described above.

  The opposing two surfaces 101 and 102 (FIG. 1A) of the optical element 10 preferably have smoothness close to a mirror surface from the viewpoint of confinement efficiency for confining light emitted from the rare earth complex 3 by total reflection. However, if the smoothness of the two opposing surfaces 101 and 102 of the optical element 10 is poor, a translucent film or sheet excellent in smoothness is separately applied to the translucent resin 1 with a transparent adhesive or adhesive. The same effect can be obtained by sticking and making the smooth surface of the attached light-transmitting film or sheet a total reflection interface.

  The rare earth complex 3 is preferably uniformly dissolved or dispersed in one or both of the translucent resin 1 and the minute region 2.

  As the rare earth complex 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. Rare earth complexes have a narrow emission wavelength band and extremely high durability, and can withstand long-term use. Therefore, compared to the case of using light emitters such as dyes and other metal complexes, emission color purity and durability It is possible to obtain the optical element 10 having excellent reliability. Therefore, for example, when the optical element 10 is used as a polarization plane light source, which will be described later, light in a desired wavelength band can be emitted without using a filter element that blocks light in an unnecessary wavelength band. More specifically, it is preferable to use a phosphor made of a rare earth complex that emits fluorescence that is light emitted from excited singlet.

More specifically, as the rare earth complex 3, a rare earth complex represented by the following chemical formulas 1 to 7 can be preferably used.

  Conventionally, the refractive index of inorganic pigments is generally 2.0 or more, and is often opaque and colored. For example, CdSe is colored red to orange, depending on the particle size and purity. When such an inorganic pigment is used as a light emitter, a resin for dispersing the light emitter (a material for forming the translucent resin 1 and the minute region 2, most of which has a refractive index of 1.5 to 1.7. In general, depolarization of excited light due to scattering caused by a large difference in refractive index and coloring of excited light caused by absorption caused by opacity and coloring of inorganic pigments in general. Is a problem. However, as described above, when the rare earth complex 3 according to the present embodiment is dissolved, depolarization or the like due to scattering does not occur, and thus the above-described problem hardly occurs. In addition, the rare earth complexes represented by the chemical formulas 1 to 7 described above are contained in a state of being dissolved in the translucent resin 1 and / or the minute region 2 in most cases.

  The optical element 10 is, for example, a combination in which regions having different birefringence are formed by using one or more suitable materials having excellent transparency, such as polymers and liquid crystals, by an appropriate orientation treatment such as a stretching treatment. It can be formed by an appropriate method such as a method for obtaining an oriented film. When the rare earth complex 3 is dispersed in the optical element 10, it is preferable that at least one of the combined materials is miscible with the dispersed rare earth complex 3.

  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.

  In addition, the compounding ratio of the rare earth complex 3 is not particularly limited, but if the compounding ratio is too small, a necessary light emission amount cannot be obtained. Therefore, the blending ratio of the rare earth complex 3 is preferably 0.1% by weight or more, more preferably 0.5% by weight or more, and further preferably 1.0% by weight or more. Note that, if the blending ratio of the light emitters 3 is excessively increased, it may be considered that the orientation and phase separation of the alignment base material (the material forming the translucent resin 1 and the minute region 2) are affected. What is necessary is just to determine suitably the mixture ratio of the range which does not produce such an influence.

  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 the combination, the target optical element 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 thereof 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 an optical element 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 monomer or It is preferable to use a combination with 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 optical element 10 using a 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 microregion portion 2 so that the liquid crystal polymer is a microregion. Can be formed by a method of forming a polymer film dispersed and contained in a state of occupying and performing an orientation treatment by an appropriate method to form regions having different birefringence.

Here, with respect to the refractive index difference between the minute region 2 and the translucent resin 1, the refractive index difference in the axial direction of the minute region 2 where the refractive index difference shows the maximum value is Δn1, and the axis showing the maximum value. A difference in refractive index in the axial direction perpendicular to the direction is denoted by Δn2 and Δn3. From the viewpoint of controllability of the refractive index differences Δn1, Δn2, and Δn3 due to the alignment treatment, the liquid crystal polymer has a glass transition temperature of 50 ° C. or higher, and the glass transition temperature of the combined polymers (translucent resin 1). It is preferable to use a material exhibiting a nematic liquid crystal phase in a lower temperature range. Specific examples thereof include a side chain type liquid crystal polymer having a monomer unit represented by the following general formula.
General formula: (-X-) _n
｜
Y-Z

  In the above general formula, X is a skeleton group that forms the main chain of the liquid crystal polymer, and may be formed by an appropriate connecting chain such as linear, branched, or cyclic. Specific examples thereof include polyacrylates, polymethacrylates, poly-α-haloacrylates, poly-α-cyanoacrylates, polyacrylamides, polyacrylonitriles, polyphthalacrylonitriles, polyamides, polyesters, Examples include polyurethanes, polyethers, polyimides, and polysiloxanes.

  Y is a spacer group branched from the main chain. The spacer group Y is, for example, ethylene, propylene, butylene, pentylene, hexylene, octylene, decylene, undecylene, dodecylene, octadecylene, ethoxyethylene, methoxybutylene from the viewpoint of the formation of the optical element 10 such as the control of the refractive index difference. And so on. On the other hand, Z is a mesogenic group that imparts liquid crystal alignment.

  The nematic alignment side chain type liquid crystal polymer may be an appropriate thermoplastic polymer such as a homopolymer or copolymer having a monomer unit represented by the general formula, and is particularly preferably excellent in monodomain alignment.

  The optical element 10 using a nematic alignment liquid crystal polymer exhibits, for example, a polymer for forming a polymer film and a nematic liquid crystal phase in a temperature range lower than the glass transition temperature of the polymer, and has a glass transition temperature. Preferably, after mixing with a liquid crystal polymer at 50 ° C. or higher, more preferably 60 ° C. or higher, particularly preferably 70 ° C. or higher to form a polymer film dispersed and contained in a state where the liquid crystal polymer occupies a minute region, the minute The liquid crystal polymer forming the region portion 2 can be heat-treated to be aligned in a nematic liquid crystal phase, and the alignment state can be formed by cooling and fixing.

  For example, a polymer film (translucent resin 1) containing dispersion of the microregions 2 before the alignment treatment, that is, a film to be subjected to the alignment treatment is, for example, a casting method, an extrusion molding method, an injection molding method, a roll molding method, a casting method. In addition to being formed by an appropriate method such as a molding method, it may also be formed by a method of developing in a monomer state and polymerizing it by heat treatment or radiation treatment such as ultraviolet rays to form a film. it can.

  In terms of obtaining the optical element 10 having excellent uniform distribution of the microscopic area 2, a method of forming a film of a mixed solution of a forming material through a solvent by a casting method, a casting method, or the like is preferable. In that case, the size and distribution of the microscopic area 2 can be controlled by the type of solvent, the viscosity of the mixed liquid, the drying speed of the mixed liquid spreading layer, and the like. In order to reduce the area of the minute region 2, it is effective to reduce the viscosity of the mixed solution or to accelerate the drying speed of the mixed solution spreading layer.

  The thickness of the alignment target film may be determined as appropriate, but in general, from the viewpoint of alignment processability, it is preferably 10 mm or less, more preferably 30 μm to 5 mm, still more preferably 50 μm to 2 mm, particularly preferably. 100 μm to 1 mm. In forming the film, for example, appropriate additives such as a dispersant, a surfactant, a color tone regulator, a flame retardant, a mold release agent, and an antioxidant can be blended.

  For example, the orientation treatment is a uniaxial, biaxial, sequential biaxial, or Z-axis stretching method, a rolling method, an electric field or a magnetic field applied at a temperature equal to or higher than the glass transition temperature or liquid crystal transition temperature, and the orientation is fixed by rapid cooling. 1 type or 2 types of appropriate methods capable of controlling the refractive index by orientation, such as a method for forming a liquid crystal, a method for fluid orientation during film formation, a method for self-orienting liquid crystals based on a slight orientation of an isotropic polymer The above can be used. Therefore, the obtained optical element 10 may be a stretched film or a non-stretched film. In addition, when setting it as a stretched film, although a brittle polymer can also be used, it is preferable to use the polymer which is excellent in ductility. Moreover, when the thickness of the film to be oriented is 2 mm or more, the orientation treatment can be suitably performed by using a rolling method or the like as the stretching treatment method.

  Further, when the minute region 2 is made of a liquid crystal polymer, for example, the liquid crystal polymer dispersed and distributed in the polymer film is heated to melt at a temperature exhibiting a desired liquid crystal phase such as a nematic liquid crystal phase, and the alignment control is performed. The alignment treatment can also be performed by a method of aligning under the action of force and quenching to fix the alignment state. The orientation state of the minute region 2 is preferably in a monodomain state from the viewpoint of preventing variation in optical characteristics.

  In addition, as the alignment regulating force, for example, a stretching force by a method of stretching a polymer film at an appropriate magnification, a shearing force at the time of film formation, an appropriate regulation that can align the liquid crystal polymer, such as an electric field or a magnetic field. Force can be applied, and the liquid crystal polymer can be subjected to alignment treatment by applying one or more kinds of regulating forces.

  The part other than the minute region part 2 in the optical element 10, that is, the translucent resin 1, may be birefringent or isotropic. The entire optical element 10 exhibits birefringence can be obtained by molecular orientation in the above-described film forming process using oriented birefringent polymers as the film forming polymers. If necessary, for example, a known orientation process such as a stretching process may be performed to impart or control birefringence. In addition, the optical element 10 other than the microregion 2 is isotropic, for example, isotropic film as a film-forming polymer, and the film is a temperature lower than the glass transition temperature of the polymer. It can be obtained by a method of stretching in the region.

  As described above, the translucent resin 1 and the minute region 2 are different in birefringence. Specifically, as described above, regarding the refractive index difference between the minute region 2 and the translucent resin 1, the refractive index in the axial direction (Δn1 direction) of the minute region 2 at which the refractive index difference shows the maximum value. When the difference is Δn1 and the refractive index difference in the axial directions (Δn2 direction and Δn3 direction) perpendicular to the axial direction showing the maximum value is Δn2 and Δn3, Δn1 is appropriately larger than the point of total reflection described later. Is preferable, and Δn2 and Δn3 are preferably as small as possible and preferably as zero as possible. The optical element 10 according to this embodiment is controlled to satisfy 0.03 ≦ Δn1 ≦ 0.5, 0 ≦ Δn2 ≦ 0.03, and 0 ≦ Δn3 ≦ 0.03, and more preferably Δn2 = Δn3. Such a difference in refractive index can be controlled by the refractive index of the material used, the orientation treatment, or the like.

  By setting such refractive index differences Δn1, Δn2, and Δn3, the linearly polarized light in the Δn1 direction is strongly scattered among the light emitted by the excitation light that has entered the optical element 10, and from the critical angle (total reflection angle). The amount of light emitted to the outside from the optical element 10 can be increased by being scattered at a small angle, while the linearly polarized light in other directions is hardly scattered, and by repeating total reflection, Can be confined.

  In addition, the refractive index difference (Δn1, Δn2, and Δn3) between each axial direction of the minute region 2 and the translucent resin 1 is small when the translucent resin 1 is optically isotropic. It means the difference between the refractive index of each axial direction of the region portion 2 and the average refractive index of the translucent resin 1, and when the translucent resin 1 is optically anisotropic, the translucent resin Since the main optical axis direction of 1 and the main optical axis direction of the minute region portion 2 normally coincide with each other, it means a difference in refractive index in each axial direction.

  Since the Δn1 direction is parallel to the vibration plane of the linearly polarized light emitted from the optical element 10, the Δn1 direction is preferably parallel to the two opposing surfaces 101 and 102 of the optical element 10. As long as the two surfaces 101 and 102 are parallel to each other, the Δn1 direction can be an appropriate direction according to the liquid crystal cell to which the optical element 10 is applied.

  It is preferable that the minute region portions 2 in the optical element 10 are distributed as evenly as possible from the viewpoint of the uniformity of the scattering effect in the minute region portion 2. The size of the minute region 2, particularly the length in the Δn1 direction, which is the scattering direction, affects backscattering (reflection) and wavelength dependency. Improvement of light utilization efficiency, prevention of coloring due to wavelength dependence, prevention of visual impairment or visualization of the fine area 2 by virtue of visualization, and prevention of vivid display, as well as film formation and film strength The preferable size of 2, particularly the length in the Δn1 direction is preferably 0.05 to 500 μm, more preferably 0.1 to 250 μm, and particularly preferably 1 to 100 μm. In addition, although the micro area | region part 2 exists in the optical element 10 in the state of a domain normally, there is no limitation in particular about the length of the (DELTA) n2 direction.

  The proportion of the minute region portion 2 in the optical element 10 can be appropriately determined from the viewpoint of the scattering property in the Δn1 direction and the like, but generally 0.1 to 70% by weight in view of the film strength and the like. More preferably, it is 0.5 to 50% by weight, and particularly preferably 1 to 30% by weight.

  The optical element 10 according to this embodiment can form a polarization plane light source by combining with an excitation light source that emits light having a wavelength that can excite the rare earth complex 3 dissolved or dispersed in the optical element 10. is there. The arrangement of the excitation light source and the optical element 10 is not particularly limited, but it is desirable that the excitation light is effectively incident on the optical element 10. From such a viewpoint, as shown in FIG. 2, the excitation light source 9 is arranged on the side surface of the optical element 10, or the excitation light source 9 is a surface light source such as an electroluminescence element as shown in FIG. It is preferable that the optical element 10 be arranged so that the flat surfaces of the optical element 10 face each other. As shown in FIG. 2, the optical element 10 may be arranged as it is, or may be integrated with the excitation light source 9 or a translucent support through a translucent adhesive layer or the like. . It is also preferable to provide a light guide plate for efficiently guiding light from the excitation light source into the optical element 10. Although there is no restriction | limiting in particular as said light-guide plate, For example, what is generally used for the backlights of a liquid crystal display, such as a flat plate and a wedge-shaped board which consist of translucent resin, and what provided the reflective dot in the said resin further Can be suitably used.

  The type of the excitation light source 9 is not particularly limited as long as it is an excitation light source that emits light having a wavelength capable of exciting the rare earth complex 3, but the rare earth complex 3 basically has a short wavelength with high energy. It is preferable to use an excitation light source that emits ultraviolet light or an excitation light source that has a light emission band from ultraviolet light to visible light because light is converted into long-wavelength light.

  More specifically, as the excitation light source 9 according to the present embodiment, in addition to a conventional ultraviolet to visible light emission light source using mercury vapor such as a hot cathode tube or a cold cathode tube, for example, Sanyo Electric or Mercury-less fluorescent tubes using materials with low environmental impact such as xenon gas manufactured and sold by Samsung Electronics, and visible light from the ultraviolet range manufactured and sold by Nichia, Toyoda Gosei, Lumileds, Courier, etc. A high-intensity LED or an inorganic / organic electroluminescence element having a light emission band over the region can be suitably used.

  Here, in a direct type backlight device using a conventional general visible light emitting light source, since a direct image of the light source itself having high emission intensity is visually recognized, the light emission uniformity is greatly impaired. For this reason, it is necessary to provide a mask that makes it impossible to visually recognize the image directly, or to provide a diffusing material whose transmittance changes directly above the light source.

  On the other hand, the polarization plane light source obtained by the combination of the optical element 10 and the excitation light source 9 according to this embodiment has excitation light incident from the excitation light source 9 and visible light generated by exciting the rare earth complex 3. Are both scattered by the minute region portion 2 or the like or reflected by the front and back surfaces of the optical element 10 to be transmitted within the optical element 10. For this reason, as shown in FIG. 4, even if the excitation light source 9 is a point light source, visible light is generated by colliding with the rare earth complex 3 and exciting the rare earth complex 3 before the excitation light is transmitted. appear. On the other hand, if the excitation light source that emits ultraviolet light or the excitation light source 9 having a light emission band from ultraviolet light as described above is used, the excitation light itself is not clearly seen with the naked eye. Never see. Therefore, as long as the light emitters 3 are uniformly dispersed, the light emission uniformity of the polarization plane light source with respect to visible light is relatively good.

  The optical element 10 according to the present embodiment can be formed as a single layer, or can be formed as two or more layers superimposed. By superimposing the optical element 10, a synergistic scattering effect more than the thickness increase can be exhibited. Such a superposed body is preferably superposed so that the Δn1 direction has a parallel relationship in each layer from the viewpoint of increasing the scattering effect. The number of overlapping may be an appropriate number of two or more layers.

  The overlapping optical elements 10 may have the same or different Δn1, Δn2, and Δn3. Also, the luminescent material 3 included in each optical element 10 may be the same material or a different material. Note that the parallel relationship in each layer with respect to the Δn1 direction and the like is preferably parallel to each other as described above, but deviation due to work error is allowed. Moreover, when there is variation in the Δn1 direction or the like in each optical element 10, it is preferable to superimpose such that the average direction has a parallel relationship.

  The superposed body of the optical element 10 and the excitation light source, the support, the light guide plate, etc., and the superposed body of the optical elements 10 are bonded through an adhesive layer or the like so that the total reflection interface becomes the outermost surface. It is formed. As the adhesive layer, for example, an appropriate adhesive such as a hot melt system or an adhesive system can be used. From the viewpoint of suppressing reflection loss, it is preferable to use an adhesive layer having a small refractive index difference with respect to the optical element 10, and it is also possible to adhere with the light-transmitting resin 1 of the optical element 10 or the resin forming the minute region portion 2. It is. As the adhesive, for example, an appropriate adhesive such as a transparent adhesive such as acrylic, silicone, polyester, polyurethane, polyether, or rubber can be used, and there is no particular limitation. However, from the standpoint of preventing changes in optical properties, a material that does not require a high-temperature process for curing or drying, or that does not require long-time curing or drying treatment is preferable. Moreover, what does not produce peeling phenomena, such as a float and peeling, on the conditions of a heating and humidification is preferable.

  Therefore, from an alkyl ester of (meth) acrylic acid having an alkyl group having 20 or less carbon atoms such as methyl group, ethyl group, and butyl group, and improved components such as (meth) acrylic acid and hydroxyethyl (meth) acrylate As an adhesive, an acrylic pressure-sensitive adhesive having a weight average molecular weight of 100,000 or more and a base polymer as a base polymer, copolymerized with a combination of the acrylic monomer and the glass transition temperature of 0 ° C. or less is preferable. Used. The acrylic pressure-sensitive adhesive also has an advantage of excellent transparency, weather resistance, heat resistance and the like.

  The attachment of the adhesive layer to the optical element 10 can be performed by an appropriate method. Specifically, for example, an adhesive component is dissolved or dispersed in a solvent composed of an appropriate solvent alone or a mixture such as toluene and ethyl acetate to prepare an adhesive solution of about 10 to 40% by weight. Is applied directly on the optical element 10 by an appropriate spreading method such as a casting method or a coating method, or an adhesive layer is formed on the separator according to this method and transferred onto the optical element 10. The method of doing is mentioned. Note that the attached adhesive layer can be an overlapping layer of different compositions and types.

  The thickness of the adhesive layer can be appropriately determined according to the adhesive strength and the like, and is generally 1 to 500 μm. Further, for the adhesive layer, as necessary, for example, natural or synthetic resins, glass fibers, glass beads, metal powder or other inorganic powders, fillers, pigments, colorants, antioxidants, etc. It is also possible to mix various additives.

  In the example shown in FIG. 2, the translucent sheet 4 having excellent smoothness is attached to the optical element 10 through the adhesive layer 8 as described above, and the attached translucent sheet is used. The smooth surface (upper surface) 4 is the total reflection interface.

  Since the optical element 10 needs to be appropriately depolarized in the process of transmitting light through the optical element 10, the optical element 10 is configured to have a phase difference as a whole or partially. Is preferred. Basically, since the slow axis (axis in the Δn1 direction) of the optical element 10 and the polarization axis (vibration plane) of linearly polarized light that is not easily scattered are orthogonal to each other, polarization conversion due to the phase difference hardly occurs. It is considered that the apparent angle changes due to slight scattering and polarization conversion occurs.

  In general, it is preferable that the optical element 10 has an in-plane retardation of 5 nm or more from the viewpoint of causing such polarization conversion, but the value varies depending on the thickness of the optical element 10. Such a phase difference is not limited to a method of adding birefringent fine particles to the optical element 10, a method of attaching it to the surface, a method of making the translucent resin 1 birefringent, a method of using them in combination, It can be applied by an appropriate method such as a method of integrally laminating a refractive film.

  In the polarization plane light source to which the optical element 10 according to the present embodiment is applied, in order to efficiently emit polarized light from one of the front and back surfaces of the optical element 10, as shown in FIG. do it. In the example shown in FIG. 2, the reflective layer 5 is arranged on the back surface (lower surface) side of the optical element 10, and the light emitted from the back surface of the optical element 10 is inverted through the reflective layer 5 without changing the polarization state. The emitted light can be concentrated on the surface of the optical element 10 to improve the luminance.

  The reflective layer 5 is preferably a mirror surface from the viewpoint of maintaining the polarization state, and is therefore preferably a reflective surface made of metal or a dielectric multilayer film. As such a metal, for example, an appropriate metal such as aluminum, silver, chromium, gold, copper, tin, zinc, indium, palladium, platinum, or an alloy thereof can be used.

  The reflective layer 5 can be directly adhered to the optical element 10 as an attached layer of a metal thin film by vapor deposition, but complete reflection is difficult and a slight absorption occurs by the reflective layer 5. Therefore, considering that the total reflection is repeated for the light transmitted through the optical element 10, there is a concern about absorption loss due to the reflective layer 5 if the direct contact is made. It is preferable that the layer 5 is simply placed in an overlapping manner (that is, an air layer is interposed between them).

  Therefore, as the reflective layer 5, it is preferable to use, for example, a reflective plate in which a metal thin film is attached to a support base material by sputtering or vapor deposition, or a plate-like material such as a metal foil or a metal rolled sheet. As the support substrate, an appropriate material such as a glass plate or a resin sheet can be used. In particular, the reflective layer 5 is preferably made by depositing silver, aluminum or the like on a resin sheet from the viewpoints of reflectance, color, handleability, and the like.

  On the other hand, as the reflective layer 5 made of a dielectric multilayer film, for example, a film described in JP-T-10-511322 can be appropriately used.

  The reflective layer 5 is disposed on the back surface of the optical element 10 as shown in FIG. 2, and when the surface and side surfaces of the optical element 10 and the light guide plate are disposed, the front and back surfaces, side surfaces, and the like, as necessary May be arranged at an appropriate place.

  As shown in FIG. 2, in the polarization plane light source to which the optical element 10 according to this embodiment is applied, the polarization maintaining lens sheet 7 and the light diffusion are provided on the light extraction surface side (upper surface side) from the optical element 10. In addition to the arrangement of the layer 6, a wavelength cut filter (not shown), a retardation film (not shown), and the like can be appropriately arranged.

  The lens sheet 7 controls the optical path of the outgoing light (linearly polarized light) from the optical element 10 while maintaining the degree of polarization, improves the directivity in the front direction advantageous for visual recognition, and the intensity of the scattered outgoing light. The purpose is to make the peak the front direction.

  As the lens sheet 7, an appropriate one that can control the optical path of scattered light incident from one surface (back surface) and efficiently emit light in a direction (front direction) perpendicular to the sheet surface from the other surface (front surface) is used. There is no particular limitation. Accordingly, any lens sheet having various lens forms used in a conventional so-called sidelight type light guide plate as described in, for example, Japanese Patent Application Laid-Open No. 5-169015 is used except for the point of maintaining the polarization. be able to.

  The lens sheet 7 shows, for example, a total light transmittance of preferably 80% or more, more preferably 85% or more, and particularly preferably 90% or more. Although the transmittance is preferably 5% or less, more preferably 2% or less, and particularly preferably 1% or less, it is preferable to use a material that has excellent light transmittance and does not eliminate the polarization characteristics of the emitted light.

  In general, since the depolarization is caused by birefringence or multiple scattering, the lens sheet 7 exhibiting polarization maintaining properties can reduce, for example, birefringence or the average number of reflections (scattering) of light transmitted inside. This can be achieved by reducing it. Specifically, for example, a resin having a low birefringence (optical isotropy) such as cellulose triacetate resin, polymethyl methacrylate, polycarbonate, norbornene resin exemplified as the polymer used for the optical element 10 described above. The lens sheet 7 exhibiting polarization maintaining property can be prepared by using one or more resins having good properties.

  As the lens sheet 7, for example, a convex lens type or a refractive index distribution type (with a refractive index controlled via a photopolymer or the like on the surface or inside of a transparent resin base material that may contain resins having different refractive indexes ( GI type) lens regions (particularly minute lens regions) formed in large numbers, a polymer region having a different refractive index filled in a large number of through holes provided in a transparent resin base material, and lens regions formed. Alternatively, it may have an appropriate lens form, such as one in which a large number of spherical lenses are arranged in a single layer and fixed with a thin film. However, from the viewpoint of optical path control due to the difference in refractive index, it is preferable that the lens sheet 7 has a lens form 71 having a concavo-convex structure as shown in FIG.

  The concavo-convex structure that forms such a lens form 71 may be any as long as it has a function of controlling the optical path of light transmitted through the lens sheet 7 and condensing the transmitted light in the front direction. A large number of linear grooves and projections such as stripes or grids, or triangular microprojections having a bottom shape such as a triangular pyramid, a quadrangular pyramid, other polygonal pyramids, a cone, etc. There can be mentioned a large number of arrays. Note that the linear or dot-like uneven structure may be a spherical lens, an aspheric lens, a semi-cylindrical lens, or the like.

  The lens sheet 7 having a linear or dotted concavo-convex structure is prepared by, for example, filling a mold formed so as to form a predetermined concavo-convex structure with a resin liquid or a monomer for resin formation, and performing a polymerization treatment as necessary. Then, it can be formed by an appropriate method such as a method of transferring the concavo-convex structure of the mold or a method of transferring the concavo-convex structure by thermocompression bonding a resin sheet to the mold. The lens sheet 7 may be formed as two or more overlapping layers of the same or different resin layers, such as a lens sheet added to the support sheet.

  The lens sheet 7 can be arranged in one layer or two or more layers on the light emitting side of the optical element 10. When two or more layers are disposed, each lens sheet 7 may be the same or different, but it is preferable to maintain the polarization maintaining property as a whole. When the lens sheet 7 is disposed adjacent to the optical element 10, as in the case of the reflection layer 5 described above, an air layer is interposed between the optical element 10 and the optical element 10, so that an air layer is interposed therebetween. It is preferable to arrange them. Moreover, it is preferable that the space | gap is fully larger than the wavelength of incident light from the point of total reflection.

  In the case where the lens form of the lens sheet 7 has a linear concavo-convex structure, the line direction is the optical axis direction of the optical element 10 (vibration plane direction of outgoing polarization) from the viewpoint of optical path control in the front direction. It is preferable to arrange so as to be in a parallel state or an orthogonal state. Moreover, when arrange | positioning two or more layers of such a lens sheet 7, it is preferable to arrange | position so that a linear direction may cross | intersect an upper and lower layer from the point of the efficiency of optical path control.

  The light diffusing layer 6 is diffused while maintaining the degree of polarization of the light emitted from the optical element 10 to make the light emission uniform, or the uneven structure of the lens sheet 7 is reduced from being visualized. The purpose is to improve.

  As the light diffusing layer 6, it is preferable to use a layer that is excellent in light transmittance and maintains the polarization characteristics of the emitted light, as with the lens sheet 7 described above. Therefore, the light diffusion layer 6 is preferably formed using a resin having a small birefringence as exemplified for the lens sheet 7. For example, transparent resin is dispersed and contained in the resin, or a fine uneven structure is formed on the surface. The light diffusing layer 6 exhibiting polarization maintaining property can be formed by using a resin layer having, etc.

  In addition, as the transparent particles dispersed and contained in the above-described resin, for example, inorganic particles that may have conductivity such as silica, glass, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide, etc. Fine particles or crosslinks such as acrylic polymer, polyacrylonitrile, polyester, epoxy resin, melamine resin, urethane resin, polycarbonate, polystyrene, silicone resin, benzoguanamine, melamine / benzoguanamine condensate, benzoguanamine / formaldehyde condensate Or the organic type | system | group fine particle etc. which consist of an uncrosslinked polymer etc. are mentioned.

  Moreover, 1 type (s) or 2 or more types can be used as said transparent particle | grains, and it is preferable that the particle size shall be 1-20 micrometers from points, such as the diffusibility of light, and the uniformity of the spreading | diffusion. On the other hand, although the particle shape is arbitrary, a (true) spherical shape or a secondary aggregate thereof is generally used. In particular, it is preferable to use transparent particles having a refractive index ratio of 0.9 to 1.1 with respect to the polarization maintaining property.

  The transparent particle-containing light diffusing layer 6 described above is, for example, a method in which transparent particles are mixed into a resin melt and extruded into a sheet or the like, or a transparent solution is mixed with a resin solution or monomer to cast a sheet or the like. And it can form by well-known appropriate methods, such as the method of superposing | polymerizing as needed, the method of coating the resin liquid containing a transparent particle on a predetermined surface, a polarization-maintaining support film, etc.

  On the other hand, the light diffusing layer 6 having a fine concavo-convex structure on the surface is, for example, a method of roughening the surface of a resin sheet by buffing or embossing by sandblasting or the like, The layer can be formed by an appropriate method such as a method of forming a layer of a functional material. However, a method of forming irregularities (protrusions) having a large refractive index difference from the resin, such as air bubbles or titanium oxide fine particles, is not preferable because polarization can be easily eliminated.

  The fine concavo-convex structure on the surface of the light diffusing layer 6 is composed of concavo-convex parts having a surface roughness of not less than the wavelength of incident light and not more than 100 μm and having no periodicity in view of light diffusibility and uniformity of diffusion. Those are preferred.

  When forming the above-described transparent particle-containing type or surface fine uneven type light diffusion layer 6, it is possible to suppress an increase in retardation due to photoelasticity or orientation, particularly in the base layer made of the resin. This is preferable from the viewpoint of maintainability.

  The light diffusing layer 6 can be disposed as an independent layer made of a plate-like material or the like, and can also be disposed as a subordinate layer that is tightly integrated with the lens sheet 7. When the light diffusing layer 6 is disposed adjacent to the optical element 10, it is preferable that the light diffusing layer 6 is disposed such that a gap is formed between the light diffusing layer 6 and the optical element 10 as in the case of the lens sheet 7. When two or more light diffusing layers 6 are arranged, each light diffusing layer 6 may be the same or different, but it is preferable to maintain the polarization maintaining property as a whole. .

  The wavelength cut filter described above is used for the purpose of preventing direct light from the excitation light source 9 from entering a liquid crystal display element or the like illuminated by the polarization plane light source according to the present embodiment. In particular, when the excitation light is ultraviolet light, it is necessary to prevent deterioration of the liquid crystal and the polarizing plate due to the ultraviolet light, and therefore a wavelength cut filter is preferably used. The wavelength cut filter can also be used for the purpose of eliminating visible light having an unnecessary wavelength.

  Examples of the wavelength cut filter include a material that absorbs a target wavelength in a resin that is transparent to visible light (salicylate ester compound, benzophenol compound, benzotriazole compound, cyanoacrylate compound). In addition to a film in which a UV absorber such as a nickel complex salt compound is dispersed or applied, or a film in which a cholesteric liquid crystal is laid on a translucent film, light of a desired wavelength is reflected by reflection of a dielectric multilayer film. And the like. Further, without providing a wavelength cut filter separately, for example, an ultraviolet absorber may be added to the optical element 10 or other optical member to provide a wavelength cut function.

  The retardation film described above is used for the purpose of converting linearly polarized light emitted from the optical element 10 into an arbitrary polarization state. For example, a quarter-wave plate as a retardation film is arranged so that the slow axis direction is at an angle of 45 ° with the linearly polarized light that is emitted, and converted into circularly polarized light, or 1/2 as a retardation film. It is possible to rotate the polarization axis of the linearly polarized light emitted by using the wave plate.

  As the retardation film, an arbitrary film such as one constituted by a polymer film that is generally used for compensation of a liquid crystal cell or one in which a liquid crystal polymer is oriented and laid on a translucent film is used. be able to.

  The lens sheet 7, the light diffusion layer 6, the wavelength cut filter, and the like described above can be used as a single layer or stacked layers. Further, it can be brought into close contact with a liquid crystal display element or the like disposed on the upper portion through an adhesive layer or the like. However, in the case of the lens sheet 7 having the concavo-convex structure described above and the light diffusing layer 6 of the surface fine concavo-convex type, an arrangement in which a gap is provided between the liquid crystal display element is preferable.

  The lens sheet 7, the light diffusion layer 6, the wavelength cut filter, and the like are connected to the optical element 10 so as not to hinder the control of the critical angle condition in the optical element 10 from the viewpoint of efficiently extracting polarized light. It is preferable to arrange | position through a space | gap between.

  The optical element 10 according to the present embodiment described above and a polarization plane light source to which the element is applied can emit light as linearly polarized light from the optical element 10 using light incident from the excitation light source 9, and its polarization direction ( For example, it can be suitably used for various devices and applications that use linearly polarized light such as a liquid crystal display device.

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

<Example>
(1) Material for optical element production Arton G grade made by JSR as a translucent resin, and a liquid crystal polymer represented by the following chemical formula 8 (n = 35, glass transition temperature 80 as a material for producing a microscopic region) And an organic metal complex represented by the following chemical formula 9 were used as rare earth complexes.

(2) 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.

(3) 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.

(4) Stretching The above dried base material was stretched 2.5 times at 170 ° C., and then rapidly cooled to produce optical elements of the examples.

  The optical element 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 and stretched under the same conditions as above, and for the liquid crystal polymer coated and aligned on the alignment film alone, respectively. 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.

<Comparative example>
An optical element serving as a comparative example was produced according to Example 1 except that fine powder of tris (8-quinolinolato) aluminum was dispersed and mixed instead of the rare earth complex. The refractive index differences Δn1, Δn2, and Δn3 of the optical element according to the comparative example were the same values as those of the optical element according to the example.

<Evaluation>
When each of the optical elements according to the example and the comparative example is irradiated with light emitted from a black light fluorescent lamp (center wavelength: 360 nm) as excitation light, straight lines having a center wavelength of 620 nm and a center wavelength of 525 nm are respectively shown in FIG. It was found that polarized light was emitted. Further, as shown in FIG. 5, in the optical element according to the example, the wavelength band of the emitted light is narrower (specifically, the half-value width is about 10 nm) and the color purity is high as compared with the optical element according to the comparative example. It was found that linearly polarized light was emitted. On the other hand, in the optical element according to the comparative example, it was found that the half-value width of the emitted light was about 100 nm, and linearly polarized light with low color purity was emitted.

  In addition, when a commercially available polarizer (degree of polarization = 99.99) was used to measure the emission intensity of each linearly polarized light component in the Δn1 direction (stretching direction as Δn1 direction) and Δn2 direction of the emitted light, It was found that 6: 1 linearly polarized light was emitted uniformly over the entire surface of the optical element according to the example, and 6: 1 with the optical element according to the comparative example.

FIG. 1 is a longitudinal sectional view showing a schematic configuration of an optical element according to an embodiment of the present invention. FIG. 2 is a longitudinal sectional view showing a schematic configuration example of a polarization plane light source to which an optical element according to an embodiment of the present invention is applied. FIG. 3 is a longitudinal sectional view partially showing a schematic configuration example in the case where another excitation light source is used in the polarization plane light source shown in FIG. FIG. 4 is a schematic diagram for explaining that uniform light emission can be easily obtained even if the excitation light source is a point light source if the optical element according to one embodiment of the present invention is applied. FIG. 5 is a characteristic diagram showing the wavelength band of light emitted from the optical elements according to Examples and Comparative Examples of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Translucent resin 2 ... Micro area | region 3 ... Luminescent material 4 ... Translucent sheet 5 ... Reflective layer 6 ... Light-diffusion layer 7 ... Lens sheet 8 ... Adhesive layer 9 ... Excitation light source 10 ... Optical element

Claims (4)

The light-transmitting resin and the light-transmitting resin are distributed and distributed, and the light-transmitting resin is formed in a plate shape having a microregion portion having different birefringence,
An optical element comprising at least one kind of rare earth complex that emits light when excitation energy is applied from the outside in the translucent resin and / or the minute region.   The optical element according to claim 1, wherein the rare earth complex is a phosphor that absorbs ultraviolet light or visible light as the excitation energy and emits visible light. The optical element according to claim 1 or 2,
A polarization plane light source comprising: an excitation light source that emits light having a wavelength capable of exciting the rare earth complex contained in the optical element.   A display device comprising the polarization plane light source according to claim 3.

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