JP4610356B2 - Optical element manufacturing method - Google Patents

Description

  The present invention relates to an optical element, a method for manufacturing the optical element, a polarization plane light source using the optical element, and a display device using the polarization plane light source. The present invention relates to an optical element that can be emitted as linearly polarized light having a predetermined vibration surface from at least one of the above, a method for manufacturing the optical element, a polarization plane light source using the optical element, and a display device using the polarization plane light source.

  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, at the time of development of the optical element described in Patent Document 14, it is considered preferable to uniformly decompose or disperse the luminescent material into one or both of the translucent resin and the minute region ( In the specification, paragraph 0026 of Patent Document 14, the optical element actually manufactured and tested for evaluation also has a structure in which the light emitting material is uniformly decomposed or dispersed. Even with such a configuration, although an optical element having a high degree of polarization was obtained compared to the comparative example described in Patent Document 14, there was a problem that it was difficult to say that the degree of polarization was practically sufficient. .
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 emits light excited and emitted through incident light as linearly polarized light having a sufficient degree of polarization from at least one surface of the front and back surfaces. and to provide a manufacturing how the optical element obtained.

  In order to solve the above-mentioned problems, the inventors of the present invention have made extensive studies, and as a result, the light emitted by irradiating the light-emitting material near the light emitting surface of the optical element with the excitation light passes through a sufficient scattering path. The scattered light that does not satisfy the Δn1 direction condition (see the description below) that is emitted to the outside of the optical element without being collided (emitted to the outside without colliding with the minute region portion or scattered by colliding with one minute region portion) It has been found that the degree of polarization as a whole of the emitted light of the optical element cannot be sufficiently obtained due to the high probability that the light exits to the outside without colliding with other minute regions. The present invention has been completed based on the knowledge of the inventors.

That is, according to the first aspect of the present invention, the translucent resin and the microscopic region where the birefringence is different between the translucent resin and the translucent resin dispersed and distributed in the translucent resin. A coating liquid containing at least one or more luminescent materials is applied to any one of the front and back surfaces of the base material formed in a plate shape with a portion, and the applied surface is dissolved. Alternatively, the concentration distribution of the luminescent material along the thickness direction of the base material can be changed between the front and back surfaces of the base material by allowing the luminescent material to penetrate into the base material by swelling and soaking. The present invention provides a method for manufacturing an optical element, characterized in that the distribution is unevenly distributed on any one of the surfaces .

  According to the first aspect of the present invention, there is no need to provide a special light emitting means made of a reflective dot or the like in the translucent resin as in the prior art, and the luminescent material contained in the optical element by the incident excitation light. The emitted light can be emitted to the outside as linearly polarized light having 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 excitation light emitted by the excitation light incident inside the optical element is totally reflected at the air interface according to the refractive index difference between the optical element and air, and transmitted within the optical element. Is done. 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 the minute region portion is not distributed and distributed in the translucent resin, the selective polarized light scattering as described above does not occur, so the light excited and emitted by the light emitting material in the optical element is Due to the solid angle, about 80% is confined in the translucent resin and is repeatedly totally reflected.

  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.

  Here, as shown in FIG. 1 (a), the light-emitting material 3 (the hatched portion in FIG. 1 is a region containing the light-emitting material 3. The same applies to other drawings). And either one or both of the minute regions 2 (both cases are shown in FIG. 1A) are uniformly contained (the concentration distribution of the luminescent material 3 along the thickness direction of the optical element 10 ′ is uniform). In some cases, the light L1 emitted when the luminescent material 3 existing in the vicinity of the light emitting surface of the optical element 10 ′ is excited by the excitation light source 9 does not pass through a sufficient scattering path (FIG. 1 ( In a), the probability of emitting the light as it is to the outside as it is (without colliding with the minute region 2) is increased, and as a result, the degree of polarization of the whole emitted light cannot be obtained sufficiently.

  However, according to the invention of claim 1, as shown in FIG. 1B, the concentration distribution of the luminescent material 3 along the thickness direction of the optical element 10 is either one of the front and back surfaces of the optical element 10. Because the concentration of the luminescent material 3 distributed on one surface side is higher than the concentration of the luminescent material 3 distributed on the other surface side. By arranging the excitation light source 9 on the one surface side, the light L1 emitted when the light emitters 3 distributed on the one surface side are excited by the excitation light source 9 is emitted from the optical element 10. As a result of passing through a sufficient scattering path before being emitted to the outside (high probability of colliding with the minute region portion 2), it becomes possible to emit the polarized light L2 satisfying the Δn1 direction condition to the outside. As a whole, it is possible to obtain a sufficient degree of polarization.

As described above, according to the first aspect of the invention, it is possible to emit light excited and emitted through incident light as linearly polarized light having a sufficient degree of polarization from one of the front and back surfaces. The “ distribution in which the concentration distribution of the luminescent material along the thickness direction of the base material is unevenly distributed on either one of the front and back surfaces of the base material ” in the invention according to claim 1 is as described above. As described above, it means that the concentration of the luminescent material distributed on one surface side is higher than the concentration of the luminescent material distributed on the other surface side. (1) When the luminescent material is contained but the concentration of the luminescent material distributed on one side is higher, and (2) the luminescent material is not contained at all on the other side. (In the case shown in FIG. 1B).
Moreover, according to the invention which concerns on Claim 1, it is possible to make a luminescent material unevenly distribute in the application surface side of a coating liquid.

In order to solve the above-mentioned problems, the present invention is characterized in that the translucent resin and the translucent resin distributed and distributed in the translucent resin are combined as described in claim 2 of the claims. A substrate having a microregion portion having a different refractive index and formed in a plate shape, and containing at least one kind of luminescent material in the translucent resin and / or the microregion portion. The concentration distribution of the luminescent material along the thickness direction of the base material is obtained by extracting or removing the luminescent material from at least one surface side of the back surface. It is also provided as a method for manufacturing an optical element, characterized in that the distribution is unevenly distributed on any one of the surfaces, or the distribution is unevenly distributed in the central portion in the thickness direction of the substrate .

The concentration distribution of luminescent materials definitive to the invention according to claim 2, according to the optical element is the distributed unevenly in the thickness direction central portion of the substrate, the concentration distribution of luminescent material along the thickness direction of the optical element However, the distribution is unevenly distributed in the central portion in the thickness direction of the optical element (the concentration of the luminescent material distributed in the central portion in the thickness direction of the optical element is higher than the concentration of the luminescent material distributed in the vicinity of the front and back surfaces. Therefore, even if the excitation light source is arranged on either side of the front and back surfaces of the optical element, the light emitted when the light emitters distributed in the central part are excited by the excitation light source As a result of passing through a sufficient scattering path before being emitted to the outside of the optical element, it becomes possible to emit the polarized light satisfying the Δn1 direction condition and obtain a sufficient degree of polarization as the entire emitted light. Is possible.

In addition, the concentration distribution of the luminescent material in the invention according to claim 2 is unevenly distributed in the central portion in the thickness direction of the base material , as described above, the luminescent property distributed in the central portion in the thickness direction of the optical element. This means that the concentration of the material is higher than the concentration of the luminescent material distributed in the vicinity of the front and back surfaces. (1) Although the luminescent material is contained in the entire optical element, it is distributed in the central portion. This is a concept that includes both the case where the concentration of the light emitting material is higher and the case (2) where no light emitting material is contained in the vicinity of the front and back surfaces.

  As the light-emitting material in the invention according to claim 1 or claim 2, it is possible to use a light-emitting body that is dispersed in the light-transmitting resin and / or the minute region and has a particle size smaller than the emission wavelength. preferable.

  Here, if the particle size of the illuminant is larger than a predetermined value, excitation light is emitted by one illuminant in the optical element, and linearly polarized light obtained by colliding with a minute region (a vibration surface parallel to the Δn1 direction is obtained). The linearly polarized light) is scattered and depolarized by colliding with other light emitters before exiting the optical element, even though the conditions for exiting the optical element are satisfied. There is a possibility that the degree of polarization may decrease. In particular, since the optical path length of the light transmitted in the optical element is relatively long and the reflection / scattering is repeated a plurality of times, there is a high probability that the light will collide with another light emitter before being emitted to the outside of the optical element. However, if the particle size of the illuminant is made smaller than its emission wavelength (visible light region) (and therefore smaller than the wavelength of the linearly polarized light), the linearly polarized light passes through almost without being scattered by other illuminants. There is almost no risk of depolarization. In other words, since light has the property of a wave, most of the objects that are smaller than the wavelength pass through without being affected. Therefore, it can be emitted as linearly polarized light having a sufficient degree of polarization.

  In addition, since the particle size of the illuminant is smaller than the emission wavelength, the particle size of the illuminant is sufficiently small with respect to the thickness of the optical element assumed in practical use, and the dispersed illuminant is an optical element. There is no appearance defect such as protrusion on the surface. Further, when the optical element is manufactured, the optical element is easily obstructed without being an obstacle to the formation of the minute region portion or being a starting point for breaking the translucent resin when the stretching process is performed.

  Furthermore, since the particle size of the illuminant is smaller than the emission wavelength, it is possible to effectively increase the luminance of the light emitted from the optical element. This is because even if light emitters having the same total weight are dispersed in the optical element, if the particle size of the light emitter to be dispersed is made smaller, a larger number of light emitters can be dispersed compared to the case where the particle size is large. Because. For example, if the particle size of each light emitter is halved under the same total weight, the total number of light emitters is 8 times and the total surface area of the light emitters is 2 times. Since the excitation light emission of the illuminant occurs on the surface of the illuminant, if the particle size of each dispersed illuminant is reduced and the total surface area in the total number of illuminants is increased, the amount of luminescence increases accordingly, and as a result It is possible to effectively increase the luminance of the light emitted from the optical element.

  As described above, as the luminescent material in the invention according to claim 1 or 2, the luminescent material dispersed in the translucent resin and / or the minute region and having a particle size smaller than the emission wavelength. Can emit light excited and emitted through incident light from at least one of the front and back surfaces as linearly polarized light having a sufficient degree of polarization, and can be easily manufactured without causing appearance defects, and the brightness of the emitted light can be reduced. It can be easily increased.

  Furthermore, it is preferable to use an inorganic pigment as the luminous body.

  Inorganic pigments have high emission brightness (emission efficiency) and extremely high durability, and can withstand long-term use. Therefore, emission brightness, durability, and reliability are higher than when using dye-based phosphors. It is possible to obtain an excellent optical element.

Further, in the method for manufacturing an optical element according to claim 2, to extract and remove the light emission material may be, for example, the one surface of the base material (or front and rear surfaces both) is allowed or dissolved swollen with solvent A method of cleaning and removing the solvent that has been caused to contain a light-emitting material can be considered. In order to deactivate the luminescent material, for example, it is conceivable to irradiate one surface (or both the front and back surfaces) of the base material with ultraviolet rays to deactivate it.

Other methods of manufacturing the optical element disclosed in 請 Motomeko 1 or 2, at least one of the surfaces of the front and rear surfaces of the light-emitting layer comprising at least one or more kinds of luminescent materials in light-transmitting resin The transparent resin and the translucent resin dispersed and distributed in the translucent resin have a micro-region part having different birefringence and are laminated and integrated into a plate-like base material It is also possible to exemplify the method of converting. More specifically, when manufacturing an optical element in which the concentration distribution of the luminescent material is a distribution unevenly distributed on either one of the front and back surfaces of the base material, either one of the front and back surfaces of the light emitting layer When manufacturing an optical element in which the base material is laminated and integrated on the surface, and the concentration distribution of the luminescent material is unevenly distributed in the central portion in the thickness direction of the base material, both on the front and back surfaces of the light emitting layer What is necessary is just to laminate | stack and integrate the said base material . Light emission layer was laminated surface side (or central portion) can be localized a luminescent material. In order to laminate and integrate the base material on at least one of the front and back surfaces of the light emitting layer, for example, it is conceivable to apply a bonding method or an extrusion molding method.

Further, as a method for manufacturing an optical element concentration distribution of luminescent material is a distribution localized in either one surface side of the front and back surfaces of the substrate, for example, a light transmissive resin, dispersed in the translucent resin Produces minute cracks (crazes) on one of the front and back surfaces of the base material formed in the shape of a plate having a micro-region having a different birefringence from the distributed translucent resin. And the method of apply | coating the coating liquid containing an at least 1 sort (s) or more of luminescent material to one side which produced the said crack can be illustrated . It is possible to unevenly distributed luminescent material was prepared Cracks side. In order to produce a fine crack (craze) on either one of the front and back surfaces of the substrate, for example, a method according to Japanese Patent No. 3156058 can be applied.

ADVANTAGE OF THE INVENTION According to this invention, the optical element which can be radiate | emitted as linearly polarized light which has sufficient polarization degree from the at least one of front and back can be manufactured by the light excited and emitted through incident light .

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.
FIG. 2 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. 2, the optical element 10 according to the present embodiment includes a translucent resin 1 and a micro-region part in which birefringence is different between the translucent resin 1 dispersed and distributed in the translucent resin 1. 2 and is formed in a plate shape. The optical element 10 contains at least one or more luminescent materials 3 in the translucent resin 1 and / or the minute region 2. The concentration distribution of the luminescent material 3 along the thickness direction of the optical element 10 is a distribution that is unevenly distributed on either one of the front and back surfaces of the optical element 10. That is, the concentration of the luminescent material 3 distributed on one surface side (the back surface (lower surface) side in the example shown in FIG. 2) is higher than the concentration of the luminescent material 3 distributed on the other surface side. It is considered expensive.

  More specifically, FIG. 2A shows an example in which the luminescent material 3 is contained only on the back surface side and the concentration is substantially uniform in the contained region. FIG. FIG. 2C shows an example in which the luminescent material 3 is contained only on the side and the concentration is lowered toward the front side. FIG. 2C shows the luminescent material 3 contained in a crack formed on the back side. For example, FIG. 2D shows an example in which a light emitting layer containing the light emitting material 3 substantially uniformly is laminated and integrated in the same kind of material as that of the translucent resin 1. 2A to 2D show an example in which the luminescent material 3 is not contained at all on the other surface side (surface (upper surface) side in the example shown in FIG. 2). The invention is not limited to this, and the light emitting material 3 may be contained in the entire optical element 10 as long as the concentration of the light emitting material 3 distributed on one surface side is higher. 2A to 2C show an example in which the light-emitting material 3 is contained in both the translucent resin 1 and the minute region 2, but the present invention is not limited to this. However, as long as the concentration of the luminescent material 3 distributed on one surface side is higher, the configuration in which the luminescent material 3 is contained only in the translucent resin 1, or in the minute region portion 2 It is also possible to adopt a configuration in which the light-emitting material 3 is contained only in.

  Further, as shown in FIG. 3, the optical element 10 according to the present embodiment has a distribution in which the concentration distribution of the luminescent material 3 along the thickness direction of the optical element 10 is unevenly distributed in the central portion of the optical element 10 in the thickness direction. It is also possible to do. That is, the concentration of the luminescent material 3 distributed in the central portion in the thickness direction of the optical element 10 can be higher than the concentration of the luminescent material 3 distributed near the front and back surfaces.

  More specifically, FIG. 3A shows an example in which the luminescent material 3 is contained only in the central portion and the concentration is substantially uniform in the contained region, and FIG. FIG. 3C shows an example in which the luminescent material 3 is contained only in the part and the concentration is lowered toward the front and back surfaces. FIG. 3C shows the luminescent material 3 in the same kind of material as the translucent resin 1. The example in which the light emitting layer containing substantially uniformly is laminated | stacked and integrated is shown. 3A to 3C show an example in which the luminescent material 3 is not contained at all in the vicinity of the front and back surfaces, but the present invention is not limited to this and is distributed in the central portion. As long as the concentration of the light emitting material 3 is higher, the light emitting material 3 may be contained in the entire optical element 10. 3A and 3B show an example in which the light-emitting material 3 is contained in both the translucent resin 1 and the minute region 2, but the present invention is not limited to this. Instead, as long as the concentration of the luminescent material 3 distributed in the center is higher, the configuration in which the luminescent material 3 is contained only in the translucent resin 1 or only in the minute region 2. A configuration in which the light emitting material 3 is contained is also possible.

  The shape of the optical element 10 is not particularly limited as long as it has at least two opposing flat surfaces. However, from the viewpoint of use as a surface light source and total reflection efficiency, as shown in FIG. The film is preferably in the form of a film having a rectangular cross section, a sheet, or a plate. In particular, it is desirable to form the film 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 less than 20 μm, the excitation light emitted from the excitation light source may be transmitted as it is and the scattering property may be impaired. As a result, luminance unevenness may occur. Further, since a sufficient transmission path for scattered light cannot be 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 as a result, it becomes impossible to effectively use all of the luminescent material 3. There is a fear.

  The two opposite surfaces 101 and 102 (see FIG. 2A) 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 luminescent material 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.

  As described above, the concentration distribution of the luminescent material 3 along the thickness direction of the optical element 10 is a distribution that is unevenly distributed on one of the front and back surfaces of the optical element 10 (see FIG. 2), or The light-emitting material 3 is dissolved or dispersed in one or both of the translucent resin 1 and the minute region 2 so that the distribution is unevenly distributed in the central portion in the thickness direction of the optical element 10 (see FIG. 3). Preferably it is. Since it is not desirable for the light-emitting material 3 to scatter light, 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 optical element 10 is formed, the luminescent material 3 is preliminarily blended with other additives as necessary in the material for forming the translucent resin 1 and the minute region 2. Although it can be dissolved or dispersed by an appropriate method such as a method, a specific method for unevenly distributing the concentration distribution as described above will be described later.

  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.

  As the luminescent material 3, it is preferable to use materials having emission wavelengths of blue, green, and red, either singly or in combination. For example, the case where the luminescent material 3 is an organic fluorescent dye (blue phosphor, green phosphor, red phosphor) will be specifically described below.

  The organic compound preferable as the blue phosphor is not particularly limited as long as the fluorescence peak wavelength in the solution state is 380 nm or more and less than 480 nm. Specifically, at least one selected from stilbene derivatives, distyrylarylene derivatives and tristyrylarylene derivatives described in JP-A-6-203963 is preferably contained. Other preferable blue phosphors include polycyclic aromatics such as anthracene, perylene, coronene, and alkyl-substituted products thereof.

  The organic compound preferable as the green phosphor is not particularly limited as long as the fluorescence peak wavelength in the solution state is 480 nm or more and less than 580 nm. Specifically, as the green phosphor, 3- (2′-pentimidazolyl) -7-N, N-diethylaminocoumarin (coumarin 535), 3- (2-benzothiazolyl) -7-diethylaminocoumarin (coumarin 540), 2 , 3,5,6-1H, 4H-tetrahydro-8-trifluoromethylquinolidino- <9,9a, 1-gh> coumarin (coumarin 540A), 3- (5-chloro-2-benzothiazolyl) -7 -Diethylaminocoumarin (coumarin 34), 4-trifluoromethyl-piperidino [3,2-g] coumarin (coumarin 340), N-ethyl-4-trifluoromethyl-piperidino [3,2-g] coumarin ( Coumarin 355), N-methyl-4-trifluoromethyl-piperidino [2,3-h] coumarin, 9-cyano-1,2,4,5 Coumarin compounds such as 3H, 6H, 10H-tetrahydro-1-benzopyrano [9,9a1-gh] quinolizin-10-one (coumarin 337), xanthine dyes such as 2,7-dichlorofluorescene, tetracene, quinacridone compounds, etc. Is mentioned.

  The organic compound preferable as the red phosphor is not particularly limited as long as the fluorescence peak wavelength in the solution state is 580 nm or more and 650 nm or less. Specific examples include dicyanomethylenepyran derivatives, dicyanomethylenethiopyran derivatives, fluorescein derivatives, and perylene derivatives used as red oscillation laser dyes described in European Patent Publication No. 0281381.

  These organic compounds are used in an amount of 0.1 to 10 mol%, preferably 0.8%, based on the organic compound forming the layer (translucent resin 1 or microregion 2) so as not to cause concentration quenching. It is necessary to make it contain in the ratio of 5-5 mol%. Note that it is preferable to use the light emitting material 3 having excellent fastness in consideration of the process of creating the optical element 10 and a decrease in light emission efficiency in the usage environment.

  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. 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 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 is a glass of a combination polymer (translucent resin 1). It is preferable to use a material exhibiting a nematic liquid crystal phase in a temperature range lower than the transition temperature. 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 incident inside the optical element 10, and the critical angle (total reflection angle) is obtained. The amount of light emitted from the optical element 10 to the outside can be increased by being scattered at a smaller angle, while the linearly polarized light in the other directions is hardly scattered, and the internal reflection of the optical element 10 is achieved by repeating total reflection. Can be trapped in.

  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 the 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 preferred 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 in the (DELTA) n2 direction etc. length.

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

  Hereinafter, a specific method for making the concentration distribution of the luminescent material 3 along the thickness direction of the optical element 10 a distribution that is unevenly distributed on one of the front and back surfaces of the optical element 10 (see FIG. 2) will be described. To do.

(1) Coating method The translucent resin 1 and the translucent resin 1 dispersed and distributed in the translucent resin 1 are provided with a microregion portion 2 having different birefringence and formed in a plate shape. By applying a coating solution containing at least one or more luminescent materials 3 to either one of the front and back surfaces of the base material, the coated surface is dissolved or swollen and soaked, so that the luminescent property is obtained. In this method, the material 3 is allowed to enter the base material. The optical element 10 obtained by such a method has a configuration corresponding to FIG. 2 (a) or (b). In the case of applying such a method, when a coating liquid using a solvent that dissolves the base material is used, integration by mutual infiltration of the coating liquid and the base material is promoted. In the case where the substrate is destroyed by the solvent, the solvent may be of a kind that swells the substrate. Further, if the coating liquid having a different composition is continuously applied before the solvent for preparing the substrate is dried, an optical element in which the coating film interface is fused and integrated can be obtained. When this method is applied, it may be appropriately selected from the combination examples of the base material and the solvent that cause dissolution or swelling shown in FIG. In addition, the luminescent material (It may be same or different from the luminescent material contained in the coating liquid) may be contained in the base material before the coating. In addition, a method is adopted in which a luminescent material (for example, rare earth ions) contained in a coating solution is soaked in a base material, and then heated or oxidized / reduced to be deposited in the base material. It is also possible.

(2) Extraction Method The translucent resin 1 and the translucent resin 1 dispersed and distributed in the translucent resin 1 are provided with a microregion portion 2 having different birefringence, and is formed in a plate shape. From one surface side of the front and back surfaces of the base material containing (uniformly containing) at least one or more luminescent materials 3 in the translucent resin 1 and / or the minute region 2, the luminescent material 3 is It is a method of removing by extraction or deactivating. The optical element 10 obtained by such a method also has a configuration corresponding to FIG. 2 (a) or (b). In order to extract and remove the luminescent material 3, for example, one surface of the base material is swollen or dissolved with a solvent (as appropriate selected from the combinations shown in FIG. 4), and the luminescent material 3 is contained. Further, a method for removing the solvent by washing can be considered. Moreover, in order to deactivate the luminescent material (for example, fluorescent dye) 3, for example, it is conceivable to irradiate one surface of the substrate with strong ultraviolet rays having a short wavelength of 300 nm or less to deactivate it.

(3) Penetration method The translucent resin 1 and the translucent resin 1 dispersed and distributed in the translucent resin 1 are formed in a plate shape with a microregion portion 2 having different birefringence. A method of producing a fine crack (craze) on one of the front and back surfaces of a base material and applying a coating liquid containing at least one luminescent material 3 to the one surface on which the crack is produced It is. The optical element 10 obtained by such a method has a configuration corresponding to FIG. In order to produce fine cracks (crazes) on either one of the front and back surfaces of the base material, for example, a method according to Japanese Patent No. 3156058 can be applied.

(4) Bonding method / extrusion method The translucent resin 1 and the translucent resin are disposed on either one of the front and back surfaces of the light-emitting layer containing at least one or more luminescent materials 3 in the translucent resin 1. The translucent resin 1 dispersed and distributed in the resin 1 is a method of laminating and integrating a substrate formed in a plate shape having a minute region 2 having different birefringence. The optical element 10 obtained by such a method has a configuration corresponding to FIG. In order to laminate and integrate the base material on either one of the front and back surfaces of the light emitting layer, for example, a bonding method or an extrusion molding method can be applied. In order to bond the light emitting layer and the base material, for example, a solvent (appropriately selected from the combinations shown in FIG. 4) that dissolves the base material (translucent resin) can be used, so that no interface exists. Can be easily integrated. It is also possible to use an appropriate adhesive or pressure-sensitive adhesive. More specifically, UV curable resins (NOA series) manufactured by NORLAND, Adekaoptomer manufactured by Asahi Denka, Nitto Denko No. An acrylic light-transmitting adhesive material such as 7 can be used. In this case, it is preferable to use an adhesive / adhesive that is close to the refractive index of the object to be bonded (the light-emitting layer and the translucent resin constituting the substrate). This is because critical reflection occurs when the refractive index difference is large, and light in a direction that forms a large angle with the normal of the bonding surface cannot be used. Note that the light emitting layer and the base material to be bonded can be individually extruded and used. Further, in order to extrude the light emitting layer and the base material, it is conceivable to perform injection integration using a continuous simultaneous extrusion molding machine having a multi-feed block and to stretch the integrated product.

  Moreover, about the specific method for setting it as the distribution unevenly distributed in the thickness direction center part of the optical element 10 (refer FIG. 3), in the extraction method of said (2), it is luminescent from both the front and back sides of a base material. A method of extracting and removing the material 3 or deactivating (the optical element 10 obtained by such a method has a configuration corresponding to FIG. 3A or 3B), or the bonding method of the above (4) In the extrusion method, it is possible to apply a method of laminating and integrating a base material on both the front and back surfaces of the light emitting layer (the optical element 10 obtained by such a method has a configuration corresponding to FIG. 3C). Is possible.

  In addition, as a method of making the luminescent material 3 contain only in the translucent resin 1, the method demonstrated below can be considered, for example. That is, first, a base slurry (aqueous solution) is prepared by mixing a dispersion (aqueous dispersion) of ZnS as a luminescent material and PVA (polyvinyl alcohol) as a translucent resin. A liquid crystal monomer UCL008 manufactured by Dainippon Ink & Chemicals, Inc. is added as a material for producing a microscopic area, and a first coating liquid containing a luminescent material only in a translucent resin is prepared.

  Next, a second coating solution having a ZnS content (concentration) different from that of the first coating solution is prepared. And a 1st coating liquid is apply | coated to predetermined thickness, it dries, and it forms into a film, and produces a 1st coating film. This 1st coating film will contain ZnS only in translucent resin. On the other hand, the second coating liquid is applied to a predetermined thickness, dried to form a film, and a second coating film having a ZnS content (concentration) different from that of the first coating film is produced. This second coating film also contains ZnS only in the translucent resin.

  Next, when bonding the first coating film and the second coating film, water is applied to at least one surface where both coating films face each other, swell and then bonded together, and then laminated with a heating roller Then, a base material is produced. Next, the base material obtained as described above is stretched about 3 times at about 80 ° C., and then rapidly cooled to produce an optical element in which ZnS is contained only in the translucent resin and ZnS is unevenly distributed. To do. In addition, you may laminate | stack the coating film which does not contain ZnS. Three or more layers having different ZnS concentrations may be used.

  In the optical element 10 manufactured as described above, the water-dispersed ZnS is dispersed only in the water-soluble PVA, and is difficult to be dispersed in the liquid crystal monomer for producing the microregion portion. It is considered that the luminescent material 3 is contained only in the inside.

  Moreover, as a method of making the luminescent material 3 contain only in the micro area | region part 2, the method demonstrated below can be considered, for example. That is, first, Coumarin 540 as a luminescent material is dissolved in a predetermined solvent (ethanol or the like), and after mixing liquid crystal monomer UCL008 manufactured by Dainippon Ink & Chemicals, Inc. as a material for producing a microscopic region, the solvent is added. Is volatilized to prepare a microscopic area.

  Next, this micro area part is mixed with the aqueous solution of PVA (polyvinyl alcohol) as a translucent resin, and the 1st coating liquid containing the luminescent material only in the micro area part is prepared. Further, a second coating liquid having a different content (concentration) of coumarin 540 from the first coating liquid is prepared.

  And a 1st coating liquid is apply | coated to predetermined thickness, it dries, and it forms into a film, and produces a 1st coating film. This 1st coating film will contain coumarin 540 only in the micro area | region part. On the other hand, the second coating liquid is applied to a predetermined thickness, dried to form a film, and a second coating film having a different content (concentration) of coumarin 540 from the first coating film is produced. This second coating film also contains coumarin 540 only in the minute region.

  Next, when bonding the first coating film and the second coating film, water is applied to at least one surface where both coating films face each other, swell and then bonded together, and then laminated with a heating roller Then, a base material is produced. Next, the substrate obtained as described above is stretched about 3 times at about 80 ° C., and then rapidly cooled, so that the coumarin 540 is contained only in the minute region and the coumarin 540 is unevenly distributed. Is made. A coating film that does not contain coumarin 540 may be laminated. Moreover, you may make three or more layers into which the density | concentration of coumarin 540 differs.

  In the optical element 10 produced as described above, the liquid crystal monomer for producing the microregion portion exhibits compatibility (dispersibility), and the luminescent material contained in the liquid crystal monomer is contained in the water-soluble PVA. Is not diffused, it is considered that the luminescent material 3 is contained only in the minute region 2.

  The optical element 10 according to the present embodiment described above can be 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 contained in the optical element 10. Is possible. 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. 5, the configuration in which 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. 5, 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. . 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 luminescent material 3, but the luminescent material 3 basically has high energy. Since light is emitted by converting short-wavelength light into long-wavelength light, it is preferable to use an excitation light source that emits ultraviolet light or an excitation light source that has an emission band from ultraviolet light to visible 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.

  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. In addition, although it is preferable that the parallel relationship in each layer with respect to the Δn1 direction and the like is parallel to each other as described above, 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. 5, the translucent sheet 4 having excellent smoothness is bonded to the optical element 10 through the adhesive layer 8 as described above, and the bonded translucent sheet is bonded. 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. 5, the reflective layer 5 is disposed 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.

  As shown in FIG. 5, the reflective layer 5 is disposed on the back surface of the optical element 10, and when a light guide plate is disposed on the front surface or side surface of the optical element 10, the front and back surfaces, side surfaces, etc. May be arranged at an appropriate place.

  As shown in FIG. 5, in the polarization plane light source to which the optical element 10 according to the present embodiment is applied, the polarization maintaining lens sheet 7 and the light diffusion are disposed on the light extraction surface side (upper surface side) of 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 to have a lens form 71 having a concavo-convex structure on the surface of the lens sheet 7 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 resin-forming monomer, 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 reflective layer 5 described above, a gap is formed between the optical element 10, that is, 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 diffusion 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 with sandblasting or the like, or a light transmitting layer having protrusions on the surface of the resin sheet. 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>
(1) Preparation of base material 95 parts (parts by weight, the same applies hereinafter) of norbornene-based resin (manufactured by JSR, Arton, glass transition temperature 182 ° C.) as a light-transmitting resin, Using a 20 wt% dichloromethane solution (mixed solution A1) in which 5 parts of a liquid crystal polymer represented by the chemical formula (glass transition temperature 80 ° C., nematic liquid crystallizing temperature 100 to 290 ° C.) 5 parts are mixed and dispersed, an applicator is formed on the glass substrate. A film having a thickness of 100 μm was formed by a casting method using, and the film was stretched three times at 180 ° C. and then rapidly cooled to prepare a base material (base material A1).

  The base material A1 is a transparent film made of a 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. 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. 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) Preparation of light-emitting layer 99.8 parts (parts by weight, the same applies hereinafter) of norbornene-based resin (manufactured by JSR, Arton, glass transition temperature 182 ° C.) to 3- (2-benzothiazolyl) -7-diethylaminocoumarin (coumarin) 540) Using a 20 wt% dichloromethane solution (mixed solution B1) in which 0.2 part was dissolved, a coating film having a thickness of 150 μm was formed on a glass substrate by a casting method using an applicator. This was air-dried at room temperature for 1 hour and then heated at 100 ° C. for 10 minutes to produce a light emitting layer (film B1) composed of a film having a thickness of 30 μm.

(3) Production of optical element The film B1 was bonded to the substrate A1. At the time of bonding, dichloromethane was applied to the surface of the base material A1 with a wire bar # 12. And after bonding film B1 together with the hand roller, it pressure-laminated by the heating roller (60 degreeC). The optical element produced by this was partly dissolved by the solvent (dichloromethane) in the vicinity of the interface between the base material A1 and the film B1, and was integrated.

<Example 2>
(1) Production of base material PVA PVA124 (polymerization degree 2400) which is PVA (polyvinyl alcohol) manufactured by Kuraray Co., Ltd. as a light-transmitting resin was dissolved in hot water at 80 ° C. to prepare a 13 wt% solution. And the liquid mixture (PVA liquid mixture) which added 15 weight% glycerol with respect to PVA solid content to this was produced. After the liquid crystal monomer UCL008 (1.45 g) manufactured by Dainippon Ink & Chemicals, Inc. is heated to 60 ° C. as an isotropic phase as a material for producing a microscopic area, the above PVA mixture (225 g) is added, The mixture was stirred with a homomixer at 6000 rpm for 20 minutes for defoaming (mixed solution A2). This mixed solution A2 was applied on a glass substrate with a thickness of 1 mm using an applicator. This was air-dried for 10 minutes, dried at 110 ° C. for 20 minutes, and further annealed at 140 ° C. for 4 minutes. The base material obtained as described above was stretched 4 times in a 60 ° C. boric acid aqueous solution (4% by weight) to prepare a base material (base material A2).

(2) Coating liquid PVA (polyvinyl alcohol) PVA 124 (polymerization degree 2400) 99.8 parts (parts by weight, the same shall apply hereinafter) as a luminescent material, and ZnS nanoparticles manufactured by Sumitomo Osaka Cement Co., Ltd. A 20 wt% aqueous solution (mixed solution B3) in which 0.2 part (solid content) of (average particle size 20 nm) was dissolved with warm water at 80 ° C. was used.

(3) Production of Optical Element A coating film of the mixed solution B3 (80 ° C.) having a thickness of 150 μm was formed on either one of the front and back surfaces of the substrate A2 by a casting method using an applicator. This was heated at 80 ° C. for 30 minutes and dried to produce an integrated optical element. In the produced optical element, the interface between the base material A2 and the coating film of the mixed solution B3 melted and interpenetrated, and a concentration gradient region of the luminescent material was obtained in the range of about 10 μm in the vicinity of the original interface.

<Example 3>
(1) Production of base material Polymethylmethacrylate (PMMA) resin (manufactured by Mitsubishi Rayon Co., Ltd., Acrypet) as translucent resin and cyano-based nematic liquid crystal (GR41 produced by Chisso Corporation) and weight The mixture was melt kneaded at a mixing ratio of 3: 1 at 220 ° C. and pelletized by a pelletizer. Then, using this pellet, an extruded film having a thickness of about 220 μm was produced by a biaxial extruder (die temperature 220 ° C.), and this was stretched 1.2 times by dry stretching, and a substrate having a thickness of about 180 μm (base material) A3) was prepared.

(2) Production of light-emitting layer UV light-emitting particles (ZnS pigment, particle size 5 to 8 μm) as a light-emitting material are melt-kneaded with polymethyl methacrylate (PMMA) resin (manufactured by Mitsubishi Rayon Co., Ltd., Acrypet) and pelletized by a pelletizer. Then, using this pellet, a light emitting layer (film B4) having a thickness of about 200 μm was prepared in accordance with the method for producing the substrate.

(3) Production of optical element Optical element obtained by laminating the base material A3 and the film B4, and generating vibration and heat between them using an ultrasonic bonding machine (Branson 2000 manufactured by Planson Co., Ltd.), and welding and integrating them. Was made. In the produced optical element, the interface between the base material A3 and the film B4 was welded with the same kind of PMMA.

<Example 4>
The mixed solution A1 described in Example 1 was applied on a stainless steel belt by a casting method to a thickness of 500 μm, and continuously, tris (8-quinolinolate) was used instead of the coumarin 540 of the mixed solution B1 described in Example 1. ) A mixed solution (mixed solution B2) obtained by dispersing and mixing aluminum fine powder was applied to a thickness of 300 μm by a casting method. This was dried and peeled from the stainless steel belt to prepare a substrate in which the interface between the two layers was melted and mixed. This base material was further stretched 3 times in an environment of 180 ° C. and then rapidly cooled to produce an optical element. In the produced optical element, the interface between the two layers disappeared and it was impossible to peel off the two layers.

<Example 5>
(1) Production of base material with cracks On the surface of base material A1 (thickness: 100 μm) described in Example 1, fine cracks (about 100 pieces / mm, depth: 25 μm) were formed by a method according to Japanese Patent No. 3156058. Produced. More specifically, first, the base material A1 was bent substantially in parallel with the molecular orientation direction to form a local bent portion. The upper and lower surfaces of the folded base material were pressed with a pressure body made of nitrile butadiene rubber, and the base body was pulled in the folding direction by vibrating the pressure body left and right. As a result, a cracked substrate was produced in which an infinite number of continuous striped cracks (crazes) were formed substantially parallel to the molecular orientation direction of the substrate.

(2) Production of optical element A dichloromethane solution in which 5 parts of 3- (2-benzothiazolyl) -7-diethylaminocoumarin (coumarin 540) was dissolved was applied to the cracked surface side of the cracked substrate and dried at room temperature. Later, surplus deposits on the surface were removed with ethanol. As a result, coumarin 540 soaked into the cracks (crazes), the surface of the base material (Arton) was dissolved by dichloromethane, and an optical element in which the crack surface was closed was produced.

<Comparative Example 1>
950 parts of norbornene-based resin (manufactured by JSR, Arton, glass transition temperature 182 ° C.) (parts by weight, the same shall apply hereinafter), liquid crystal polymer represented by the same chemical formula as in Example 1 described above (glass transition temperature 80 ° C., nematic liquid crystal formation) A film having a thickness of 100 μm was formed by a casting method using a 20 wt% dichloromethane solution in which 50 parts of temperature (100 to 290 ° C.) and 2 parts of 3- (2-benzothiazolyl) -7-diethylaminocoumarin (coumarin 540) were dissolved, It was stretched three times at 180 ° C. and then rapidly cooled to produce an optical element.

  The optical element 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, the refractive index difference Δn1 is 0.23, n2 and Δn3 were each 0.029. 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.

<Example 6>
In accordance with Comparative Example 1, a fluorescent dye coumarin-containing substrate (however, before stretching, thickness of 100 μm) was prepared. The mixed solution A1 described in Example 1 was applied to this substrate by a casting method and dried to prepare a substrate having a total thickness of 200 μm. The base material was stretched 3 times, and Unidic 17-806 (Toluene: 20 wt%, Irg 184: 5 wt%) manufactured by Dainippon Ink & Chemicals, Inc. was dried on the surface where the mixed solution A1 was not applied. After coating at a thickness of 5 μm and drying at 100 ° C. for 2 minutes, ultraviolet irradiation at 100 mW / cm ² was performed for 1 second with an ultraviolet irradiator. As a result, the concentration distribution of the luminescent material (coumarin) along the thickness direction of the optical element thus produced becomes a distribution that is unevenly distributed at the center in the thickness direction, and the application surface side of the mixed solution A1 functions as a polarized light exit surface. The coated surface side of Dick 17-806 functioned as a coumarin leaching prevention layer.

<Reference example>
Using a 20 wt% dichloromethane solution according to Comparative Example 1, a coating film having a thickness of 500 μm was formed by a casting method on a glass substrate that had been subjected to a release treatment by a release treatment agent die-free manufactured by Daikin Chemical Co., Ltd. Was dried until the solvent content became 20% by weight, and then peeled off from the glass substrate to prepare a substrate C1. Similarly, using the mixed solution A1 described in Example 1, a coating film having a thickness of 300 μm is formed by a casting method on a glass substrate that has been subjected to a release treatment, and this has a solvent content of 20% by weight. The substrate C2 was peeled off from the glass substrate after being dried. Next, the base material C1, the base material C2, and the base material C1 were laminated in this order, pressed and adhered at 80 ° C. with a heating laminator, and further heated and dried at 110 ° C. for 5 minutes to remove the residual solvent. As for the base material produced by this, the adhesive interface was integrated. This base material was stretched 3 times in an environment of 180 ° C. and rapidly cooled and fixed to produce an optical element. The concentration distribution of the luminescent material (coumarin) along the thickness direction of the manufactured optical element was a distribution in which the concentration in the central portion in the thickness direction was low and the concentration in the vicinity of the front and back surfaces was high.

<Comparative example 2>
PVA PVA124 (polymerization degree 2400) which is PVA (polyvinyl alcohol) manufactured by Kuraray Co., Ltd. was dissolved in 80 ° C. warm water to prepare a 13 wt% solution. And the liquid mixture (PVA liquid mixture) which added 15 weight% glycerol with respect to PVA solid content to this was produced. Dainippon Ink & Chemicals, Inc. liquid crystal monomer UCL008 (1.45 g) and Sumitomo Osaka Cement Co., Ltd. ZnS nanoparticles (solid content: 1.45 g) were mixed, heated to 60 ° C. and made isotropic, Of PVA (225 g) was added, and defoamed by stirring at 6000 rpm for 20 minutes with a homomixer. This mixed solution was applied on a glass substrate with a thickness of 1 mm using an applicator. This was air-dried for 10 minutes, dried at 110 ° C. for 20 minutes, and further annealed at 140 ° C. for 4 minutes. The base material obtained as described above was stretched 4 times in a 60 ° C. boric acid aqueous solution (4 wt%) to produce an optical element.

<Evaluation>
The transmission ratio was evaluated for each of the optical elements of Examples 1 to 6, Comparative Examples 1 and 2, and Reference Example. Specifically, each optical element is irradiated with light emitted from a black light fluorescent lamp (center wavelength: 360 nm) as an excitation light source (the concentration distribution of the luminescent material is unevenly distributed on one of the front and back surfaces of the optical element) In the case of the above distribution, irradiation is performed from the higher density surface side), and the polarized light emission generated thereby is an absorptive linear polarizer disposed opposite to each optical element (polarization degree: 99.9% or more, Nitto) The amount of light transmitted through TEG1465DU) was measured, and the transmission ratio was calculated. Here, the amount of transmitted light was measured from an angle at which direct light from the excitation light source is not visually recognized (an angle of 45 ° with respect to the normal line of the optical element). The transmission ratio is the amount of transmitted light when the stretching axis of the optical element is orthogonal to the polarization axis of the polarizer, and the amount of transmitted light when the stretching axis of the optical element is parallel to the polarization axis of the polarizer. And the transmission ratio = (the larger transmitted light amount / the smaller transmitted light amount).

  FIG. 7 shows the evaluation results. In addition, the micro area part average diameter shown in FIG. 7 means the length of the long axis side of a micro area part. As shown in FIG. 7, it was found that the optical elements of Examples 1 to 6 had a larger transmission ratio (that is, a higher degree of polarization) than the optical elements of Comparative Examples 1 and 2.

FIG. 1 is an explanatory diagram for explaining the reason why the degree of polarization can be increased by the present invention. FIG. 2 is a longitudinal sectional view showing a schematic configuration of an optical element according to an embodiment of the present invention. FIG. 3 is a longitudinal sectional view showing a schematic configuration of an optical element according to another embodiment of the present invention. FIG. 4 is a table showing examples of combinations of base materials and solvents that cause dissolution or swelling. FIG. 5 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. 6 is a longitudinal sectional view partially showing an example of a schematic configuration in the case where another excitation light source is used in the polarization plane light source shown in FIG. FIG. 7 is a table showing the results of evaluating the degree of polarization of the optical element according to one embodiment 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 (3)

Whichever of the front and back surfaces of the substrate formed into a plate-like shape comprising a translucent resin and a microregion portion having a birefringence different from that of the translucent resin dispersed and distributed in the translucent resin By applying a coating liquid containing at least one or more luminescent materials on one of the surfaces, the coated surface is dissolved or swollen so that the luminescent material is contained inside the substrate. By intruding into
  The method of manufacturing an optical element, wherein the concentration distribution of the luminescent material along the thickness direction of the base material is a distribution that is unevenly distributed on one of the front and back surfaces of the base material. The translucent resin and the translucent resin dispersed and distributed in the translucent resin are formed in a plate shape including a microregion portion having different birefringence, and the translucent resin And / or by extracting or deactivating the luminescent material from at least one of the front and back surfaces of the base material containing at least one or more luminescent materials in the minute region portion,
  The concentration distribution of the luminescent material along the thickness direction of the base material is a distribution that is unevenly distributed on either one of the front and back surfaces of the base material, or a distribution that is unevenly distributed in the central part of the base material in the thickness direction. A method for manufacturing an optical element.   Whichever of the front and back surfaces of the substrate formed into a plate-like shape comprising a translucent resin and a microregion portion having a birefringence different from that of the translucent resin dispersed and distributed in the translucent resin By creating a fine crack on one side, and applying a coating liquid containing at least one luminescent material on the one side on which the crack is produced,
  The method of manufacturing an optical element, wherein the concentration distribution of the luminescent material along the thickness direction of the base material is a distribution that is unevenly distributed on one of the front and back surfaces of the base material.