JP2000028808A - Light distribution control element and its production as well as display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light distribution control element constituted to obtain a high transmittance by suppressing a colored adhesive layer from remaining on the light exit side surface of transparent beads. SOLUTION: The hot melt adhesive layer 104 of the light distribution control element comprising a transparent base material 101, the hot melt adhesive layer 104 formed on this transparent base material and microsphere-like transparent beads 105 consisting of one layer embedded in the hot melt adhesive layer is formed by laminating a transparent adhesive layer 102 and the colored adhesive layer 103 in this order on the transparent base material. In addition, the transparent adhesive layer having the softening temp., or melting temp. or melting viscosity higher than that of the colored adhesive layer 103 is formed and is composed of the structure in which the transparent beads 105 come into contact with the surface of the transparent base material 101. A material which is lower in the softening temp., or melting temp. or melting viscosity of the colored adhesive layer contg. coloring materials, such as carbon black lower than that of the transparent adhesive layer, or conductive particulates or magnetic powder is compounded with the colored adhesive layer 103.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light distribution control element used as a viewing angle widening member for a rear projection type display device or a liquid crystal display device, a method of manufacturing the same, and a display device display using this element.

[0002]

2. Description of the Related Art The demand for rear projection display devices is relatively large, especially in the North American market, because they can realize a large-screen display at a small size and at low cost relatively easily as compared with a direct-view CRT.
FIG. 7 is a schematic configuration diagram illustrating an example of a rear projection display device. As shown in FIG. 7, the rear projection type display device includes a projection device 701, a mirror 702, and a transmission type screen 703, and the projection light 704 from the projection device 701 is reflected by the mirror 702.
Then, the image is displayed on the transmission screen 703 via the. The transmissive screen 703 generally includes a Fresnel lens sheet 1402 and a lenticular lens sheet 1401, as shown in FIG. The Fresnel lens 1402 is an optical component having the same function as the convex lens, and has a function to bend the direction of the projection light emitted from the projection device 701 to the observer side to widen the suitable viewing range. In addition, the lenticular lens 1401 aims to effectively distribute the limited projection light from the projection device to the observation range of the observer and obtain a bright image. 14 and 15 show an example of the lenticular lens 1401. FIG. 14 is a partial sectional view, and FIG. 15 is a partial perspective view. The lenticular lens 1401 is a cylindrical lens-like lens 1501
Are arranged in one direction, and a black stripe 1502 is provided in a portion other than the light condensing portion. By setting the focal position of the lens to the observation surface of the screen, ideally, the projection light The configuration is such that a decrease in the contrast ratio with respect to external light can be suppressed without loss. In general, the lenticular lenses are arranged so that their generatrix is vertical, so that a wide light distribution characteristic can be obtained in the horizontal direction. Therefore, the light distribution in the vertical direction is considerably narrower than that in the horizontal direction because it is only diffused by the diffusing agent mixed in the base material of the lenticular lens. In addition, since the lenticular lens has linear lenses arranged regularly, moiré interference fringes are likely to occur in an image. On the other hand, in the transmission screen described in Japanese Patent Application Laid-Open No. 2-77736, a spherical lens 1602 is spread over a transparent base 1601 and fixed with a transparent resin as shown in FIG. In this configuration, since a mold is not used, there is no limitation on the size in manufacturing, and therefore, a large-screen transmissive screen without any seams can be realized. Light incident from the spherical lens side is collected by the lens effect of the spherical lens and isotropically diffused, so that a wide viewing angle can be obtained in both the horizontal and vertical directions. Further, in the flat lens described in JP-A-9-318801, microsphere-shaped transparent beads are fixed on a transparent substrate by a colored hot-melt adhesive layer and a transparent hot-melt adhesive layer. According to this configuration, a wide viewing angle can be obtained in both the horizontal and vertical directions due to the lens effect of the spherical beads, as in the transmission screen disclosed in the above publication. Further, since unnecessary light incident on the flat lens from the outside is absorbed by the colored adhesive layer, there is an effect that unnecessary light from the outside becomes stray light and is not observed.

[0003]

The above-mentioned flat lens (hereinafter referred to as a light distribution control element) was manufactured as follows.
A flat polyethylene terephthalate resin film having a thickness of 120 μm was used as a transparent base material, and a transparent adhesive layer made of a polyester-based hot melt adhesive was formed on the surface with a thickness of 5 μM
m, and a 4.5 μm colored adhesive layer formed by blending 10 parts by weight of carbon black with a polyester-based hot-melt adhesive is formed thereon, and then solidified once. On top of this, the refractive index is 1.935 (wavelength 589.3 nm) and the diameter is 50 μm.
The spherical transparent beads made of glass are densely dispersed and placed in a thermostat kept at a high temperature, so that the temperature of the transparent adhesive layer and the colored adhesive layer is raised and softened, and the pressure plate is pressed. The transparent beads are buried in the colored adhesive layer and the transparent adhesive layer by pressing the transparent beads toward the transparent substrate side by,
Stuck. The thickness of the adhesive layer after fixing the transparent beads was about 21 μm in total of the transparent adhesive layer and the colored adhesive layer, and about 58% of the diameter of the transparent beads was exposed from the adhesive layer. When the produced light distribution control element was evaluated as a transmissive screen member of a rear projection display device, an isotropic and wide viewing angle of 50 ° or more in both the horizontal and vertical directions (here, 1/1 with respect to the front luminance). 2). Further, since unnecessary light incident on the light distribution control element from the outside is absorbed by the colored adhesive layer, low-luminance black display can be realized even in a bright environment. However, it was found that sufficient brightness could not be obtained during white display. Then, when the manufactured light distribution control element was evaluated alone, it was found that the total light transmittance was about 25% lower than the theoretical value (the transmittance obtained when the light distribution control element could be ideally configured). I understood.
The inventor of the present application has conducted a more detailed study of the light distribution control element in order to find a cause of a decrease in transmittance. As a result, it has been found that the main cause of the decrease in transmittance is that the colored adhesive layer wraps around the light emitting surface side of the transparent beads and remains and absorbs light that should originally pass therethrough. In the conventional structure and manufacturing method, when the transparent beads are embedded in the adhesive layer, the colored adhesive layer and the transparent adhesive layer soften or melt almost simultaneously. Therefore, as illustrated in FIG. 17, when the transparent beads 1701 are pressed toward the transparent substrate 1702, the transparent beads 1701 are pressed.
A part of the colored adhesive layer 1703 pushed by 1 is pushed away by the transparent beads 1701, but another part is pushed into the transparent adhesive layer 1704 while being held by the transparent beads 1701, and the transparent beads 1701 are further pushed. As you pressurize,
Most of the transparent adhesive layer 1704 and the colored adhesive layer 1703 are both pushed out from the light emitting surface side of the transparent beads 1701, but a part of the colored adhesive layer 1703 is completely pushed to the light emitting side of the transparent beads 1701. Remains. Since the residual colored adhesive absorbs the light that should originally pass through, the transmittance is reduced. In particular, when the same resin is used as the base of the colored adhesive layer 1703 and the transparent adhesive layer 1704, by adding a coloring material such as carbon black,
The colored adhesive softens or has a higher viscosity when melted than the transparent adhesive. For this reason, the colored adhesive layer 1703 is easily pushed into the transparent adhesive layer 1704 while being held by the transparent beads, and the colored adhesive layer 1703 remains on the transparent bead light emitting surface more remarkably. Was significantly reduced. In order to reduce the light loss due to the residual colored adhesive layer, it is conceivable to reduce the thickness of the colored adhesive layer 1703 or to reduce the blending amount of pigments or dyes. Since the absorption of unnecessary light by the colored adhesive layer 1703 is reduced, the effect of reducing stray light due to external unnecessary light in a bright environment, which is an advantage of the present light distribution control element, is diminished. Further, when such a light distribution control element is used in a rear projection display device or a liquid crystal display device, the transmittance is significantly reduced, and the luminance of a display image is reduced,
On the other hand, when a coloring material such as carbon black is thinned, the effect of reducing stray light due to external unnecessary light in a bright environment is weakened, so that there is a problem that a high contrast ratio cannot be obtained.

In view of the above problems, an object of the present invention is to provide a light distribution control element in which a colored adhesive layer is suppressed from remaining on the light emitting surface side of a transparent bead and a high transmittance is obtained. It is another object of the present invention to provide a method of manufacturing the light distribution control element and a display device in which the brightness of a display image is improved and the contrast ratio is high.

[0005]

Means for Solving the Problems To solve the above problems, a microsphere comprising a transparent base material, a hot melt adhesive layer formed on the transparent base material, and a single layer embedded in the hot melt adhesive layer is provided. In a light distribution control element composed of transparent beads in a shape, a hot-melt adhesive layer is formed by laminating a transparent adhesive layer and a colored adhesive layer in this order on a transparent base material, and at the same time, softening temperature or melting temperature or melt viscosity. Is a transparent adhesive layer higher than the colored adhesive layer. Here, a material is added to the colored adhesive layer such that the softening temperature or the melting temperature or the melt viscosity of the colored adhesive layer containing a coloring material is lower than that of the transparent adhesive layer. Further, conductive fine particles or magnetic powder is blended in the colored adhesive layer. In order to solve the above problems, in a method for manufacturing a light distribution control element, a transparent bead is heated and softened or melted while pressing a transparent bead toward a transparent substrate. And pressing the colored adhesive layer and the transparent adhesive layer further, wherein only the colored adhesive layer is softened or melted, while the transparent adhesive layer is in a solidified or semi-solidified state or a colored adhesive layer. The transparent beads are buried in the colored adhesive layer and buried or hardly buried in the transparent adhesive layer. Here, in the process of heating only the colored adhesive layer above the softening temperature or the melting temperature, electromagnetic energy that is absorbed by the colored adhesive layer and not absorbed by the transparent adhesive layer and the transparent substrate is used. In addition, the colored adhesive layer contains conductive fine particles, and in the process of heating only the colored adhesive layer above the softening temperature or the melting temperature, a power supply voltage is applied to the colored adhesive layer, and Joule heat due to resistance loss is used. . Also, the colored adhesive layer contains a magnetic powder,
In the process of heating only the colored adhesive layer above the softening temperature or the melting temperature, a high frequency power supply is connected to the colored adhesive layer and high frequency induction heating is used. In order to solve the above problem, a projection device including a light source, two-dimensional optical switch means for modulating light from the light source according to image information and forming an optical image, and a projection lens for enlarging and projecting the optical image is provided. And a transmissive screen for projecting light from the projecting device from the rear and displaying it on the front, wherein the light flux collimating means includes a transmissive screen provided on the incident side of the projected light. The light distribution control element comprises a transparent base material, a transparent adhesive layer and a colored adhesive layer laminated on the transparent base material in this order, and a softening temperature or a melting temperature or a melting temperature. A transparent adhesive layer having a higher viscosity than the colored adhesive layer. A first transparent substrate on which a transparent electrode and a light distribution film are laminated; a second transparent substrate on which a light distribution film and a transparent electrode are laminated and having a switching element; A liquid crystal display device comprising a liquid crystal panel comprising a liquid crystal layer sandwiched between transparent substrates, and polarizers and analyzers disposed on the back and front of the liquid crystal panel, respectively, wherein light substantially parallel to the back of the polarizer is provided. A backlight device that emits light is arranged, a light distribution control element is arranged in front of the analyzer, and the light distribution control element is composed of a transparent substrate, a transparent adhesive layer and a colored adhesive layer on the transparent substrate. Are laminated in this order to form a transparent adhesive layer having a softening temperature, a melting temperature, or a melt viscosity higher than that of the colored adhesive layer.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 show one embodiment of the light distribution control element of the present invention. FIG. 1 is a partial schematic cross-sectional view of the light distribution control element, and FIG. 2 is a partial schematic perspective view of the light distribution control element. The light distribution control element 100 includes:
It is composed of a transparent substrate 101, a hot-melt adhesive layer 104 formed on the surface of the transparent substrate 101, and a plurality of microsphere-shaped transparent beads 105 fixed to the hot-melt adhesive layer 104. The transparent substrate 101 may be a plate-shaped substrate having rigidity itself, or may be a film-shaped substrate. Specifically, glass or a transparent resin such as an acrylic resin, a polycarbonate resin, a vinyl chloride resin, a polyester resin, a cellulose resin, and a polyolefin resin is used. Hot melt adhesive layer 1
04 has a configuration in which a transparent adhesive layer 102 and a colored adhesive layer 103 are laminated in this order on a transparent base material 101, and the softening temperature or melting temperature or melt viscosity of the transparent adhesive layer 102 is higher than that of the colored adhesive layer 103. Higher layer. The hot melt adhesive layer 104 includes the transparent substrate 101 and the transparent beads 1.
It is necessary to use an adhesive having a sufficient adhesive strength to the adhesive layer 05, for example, a hot melt adhesive made of an acrylic resin, a polyester resin, a polyamide resin, a polyurethane resin, or the like. The colored adhesive layer 103 may be colored with a coloring material based on these resins, and is realized by, for example, dispersion of a pigment or dyeing with a dye. If the color of the colored adhesive layer 103 is black, the effect of increasing the contrast ratio is high, so it is desirable to color the layer with a black pigment such as carbon black or a black dye. However, if there is a purpose of coloring a specific color depending on the application, the coloring may be performed with a coloring material of another color. Transparent beads 1
For 05, spherical transparent beads made of glass or resin are used. The higher the refractive index of the transparent bead 105 is, the larger the refraction angle of light incident on the transparent bead 105 becomes.
Although the emission characteristics (viewing angle) finally obtained are widened, the front luminance is reduced and the reflection on the surface of the transparent beads 105 and the reflection at the interface between the transparent base material 101 and air are increased. Light transmittance is reduced. In order to eliminate light loss through the opening of the transparent beads 105 on the light emitting surface side, that is, the contact portion between the transparent beads 105 and the transparent adhesive layer 103, the transparent beads 1
It is necessary to reduce the light condensing area of the light incident on the light emitting surface of the transparent beads 105 incident on the transparent beads 105. In this case, if the light incident side of the transparent beads 105 is air, the refractive index is 1.6 to
If it is about 2.1, the light can be condensed to a small extent on the light emitting surface of the transparent beads 105. Therefore, the refractive index of the transparent beads 105 is desirably in this range. Further, if the refractive index of the transparent beads 105 is 1.9 to 2.1, light can be collected with smaller aberration. The refractive index of the transparent beads 105 may be selected in consideration of these conditions so as to conform to desired characteristics required for the light distribution control element, that is, required specifications of a viewing angle and brightness. The diameter of the transparent beads 105 directly affects the resolution of an image displayed on the light distribution control element 100. That is, the image displayed on the light distribution control element cannot be resolved to a size smaller than the diameter of the transparent beads 105. Therefore, the diameter of the transparent beads needs to be smaller than the pixel of the image displayed on the light distribution control element. Note that in order to obtain high resolution, the smaller the diameter of the transparent beads 105, the better. However, as the diameter of the transparent beads 105 approaches the wavelength region of light, the scattering factor of transmitted light increases, and luminance and transmission in front of the transparent beads 105 increase. Since the rate decreases, the lower limit is naturally defined. Therefore, it is realistic that the diameter of the transparent beads 105 is 1 μm to about 1/2 of the pixel pitch of the displayed image. In addition, if air bubbles are present inside the transparent beads 105, this will cause a decrease in transmittance. Therefore, it is necessary to use transparent beads having as few air bubbles as possible.

Next, FIG. 3 shows an embodiment of a method for manufacturing the light distribution control element 100 used in the display device of the present invention. In FIG. 3, first, a heat-melted state is placed on a transparent substrate 101,
Or a hot melt transparent adhesive in a state of being melted in a solvent or dispersed in a solution in a colloidal state, for example, spin coating, knife coating, roll coating, spray coating,
Alternatively, the transparent adhesive layer 1 is formed by blade coating or the like.
No. 02 is formed (FIG. 3A). Further, a colored adhesive layer 103 is laminated thereon in the same manner as the transparent adhesive layer 102 to form a hot melt adhesive layer 104 (FIG. 3).
(B)). At this time, in order to prevent the colored adhesive layer 103 and the transparent adhesive layer 102 from mixing, the colored adhesive layer 1
03 is formed by lowering the temperature by forced cooling or natural cooling when the transparent adhesive layer 102 is in a high-temperature molten state, or by dispersing the transparent adhesive layer 102 in a molten state in a solvent or in a colloidal state in a solution. If it is in a state, it may be performed after solidification or semi-solidification by blowing off the solvent or solution by a dryer. Transparent adhesive layer 102 and colored adhesive layer 103 formed on transparent substrate 101
Is temporarily cooled by forced cooling or natural cooling, or a solvent or a solvent is blown off by a dryer to be solidified or semi-solidified. Next, a plurality of transparent beads 10
5 are dispersed and arranged on the colored adhesive layer 103 so as to have a maximum packing density as much as possible (FIG. 3).
(C)). At this time, the colored adhesive layer 103 is in a solidified or semi-solidified state and has no adhesive property.
05 can be relatively easily distributed to the maximum packing density. Next, the transparent beads 105 are pressed against the transparent substrate 101 at a predetermined pressure by its own weight or a pressing means such as a pressing plate while heating these by heating means described in detail later. Since the transparent adhesive layer 102 and the colored adhesive layer 103 are softened or melted with an increase in temperature, the transparent beads 105 are embedded in the transparent adhesive layer 102 and the colored adhesive layer 103 by a predetermined amount. Here, in the light distribution control element of the present invention, during this manufacturing process, only the colored adhesive layer 103 is softened or melted, while the transparent adhesive layer 102 is solidified or semi-solidified, or the colored adhesive layer The transparent beads 105 are kept buried in the colored adhesive layer 103 but kept in a state where the viscosity is higher than that of the transparent adhesive layer 103, but are not buried in the transparent adhesive layer 102 or hardly buried. As a method for obtaining this state, only the colored adhesive layer 103 is heated by a method and an apparatus described later in detail to soften or melt,
Alternatively, the softening temperature or the melting temperature of the colored adhesive layer 103 is made higher than that of the transparent adhesive layer 102, or the melt viscosity of the colored adhesive layer 103 is made higher than that of the transparent adhesive layer 102. Is done. Therefore, the transparent beads 105 are temporarily buried in the colored adhesive layer 103, but are not buried in the transparent adhesive layer 102, or are hardly buried. Most of 103 is extruded from the light emitting surface side of the transparent beads 105 without being pushed into the transparent adhesive layer 102 (FIG. 3D). Thereafter, when the transparent adhesive layer 102 is softened or melted and the transparent beads 105 are embedded in the transparent adhesive layer 102, the colored adhesive layer 103 on the light emitting surface side of the transparent beads 105 is further extruded together with the transparent adhesive layer 102. Therefore, the colored adhesive layer 103 is prevented from wrapping around the light emitting side of the transparent beads 105 and remaining. Next, with the transparent beads 105 buried,
The temperature of the transparent adhesive layer 102 and the colored adhesive layer 103 is lowered by natural cooling or forced cooling, and the transparent beads 105 are fixed by solidification (FIG. 3E). In addition,
The burying depth of the transparent beads 105 in the hot melt adhesive layer 104 is set so that 50 to 80% of the diameter of the transparent beads 105 is exposed. This is because, when the amount of exposure of the transparent beads 105 is smaller than this, the amount of light incident on the transparent beads 105 decreases due to absorption by the colored adhesive layer 103, and the transmittance decreases. Is too large, the adhesion of the transparent beads 105 to the hot melt adhesive layer 104 becomes insufficient.

Light distribution control element 1 manufactured by the above method
In the case of 00, the transparent beads 105 are dispersed and arranged at almost the maximum packing density for one layer, and a portion of more than half of the diameter is exposed to the light incident side from the hot melt adhesive layer 104 and fixed to the transparent substrate 101. It will be in the state that was done. At this time, the colored adhesive layer 103 is prevented from wrapping around or remaining on the light emitting surface side of the transparent beads 105, so that the transparent beads 105 are suppressed.
A sufficient contact portion is secured between the light exit surface and the transparent adhesive layer 102, and an opening is formed.

Next, the optical action and effect of the light distribution control element 100 manufactured according to the present embodiment will be described with reference to FIG. As described above, in the light distribution control element 100, one layer of the transparent beads 105 is dispersed and arranged at almost the maximum packing density on the light incident surface side, and a half or more of the diameter thereof is removed from the hot melt adhesive layer 104. It is exposed and fixed on the light incident side. Therefore, a part of the parallel light 106 perpendicularly incident on the light distribution control element 100 is absorbed by the colored adhesive layer 103 in the gap between the transparent beads 105, but most of the light is incident on the transparent beads 105. . The light incident on the transparent beads 105 passes through the opening formed in the contact portion between the transparent beads 105 and the transparent adhesive layer 102 while being condensed by the refraction of the transparent beads 105, and passes through the transparent substrate 101. Then, the light is diffused and emitted isotropically. At this time, the transparent beads 105
Since the colored adhesive layer 103 does not wrap around or remain on the light exit surface, the light incident on the transparent beads 105 passes through without being absorbed. In other words, in the light distribution control element 100, the colored adhesive layer on the light emitting surface of the transparent beads 105, which caused the decrease in transmittance, hardly remains. High transmittance can be obtained without sacrificing the effect of reducing stray light due to external unnecessary light by reducing the blending amount of pigments and dyes.
Therefore, the effect of reducing stray light due to external unnecessary light in a bright environment is high, and the observer is bright even when viewed from any angle,
A light distribution control element having isotropic viewing angle characteristics can be obtained.

Next, a method for manufacturing the light distribution control element of the present invention will be described based on examples. As Example 1, the light distribution control device shown in FIGS. 1 and 2 was produced as follows. In addition,
The light distribution control element of this embodiment is characterized in that the softening or melting temperature of the transparent adhesive layer 102 is higher than the softening or melting temperature of the colored adhesive layer 103. First, thickness 2
A hot-melt transparent adhesive containing a copolymer of polymethyl methacrylate and polymethacrylic acid as a main component is dried on one surface of a flat transparent base material 101 made of glass having a thickness of 4 μm. The composition is applied by a spin coater and dried by a drier to form and solidify the transparent adhesive layer 102. Next, a colored adhesive layer 103 obtained by mixing 10 parts by weight of carbon black with a hot-melt adhesive containing polymethyl methacrylate as a main component is coated with a transparent adhesive so that the thickness after drying becomes 5.5 μm. Layer 102
Formed and solidified in the same manner as described above. Next, the refractive index is 1.935 (wavelength 589.3 nm) and the diameter is 50 μm.
A plurality of spherical transparent beads 105 made of glass are dispersed and arranged so as to have almost the maximum packing density, and these transparent beads 105 are pressed against the transparent substrate 101 at a pressure of 4.5 kg / cm ² by a pressing plate. While introducing into a thermostat kept at a high temperature and keeping at 105 ° C. for 20 minutes. Here, the softening temperature of the transparent adhesive layer 102 used in this example was 110 ° C., and the softening temperature of the colored adhesive layer 103 was 95 ° C. Therefore, when heated at 105 ° C., the colored adhesive layer 103
Only the softening occurs, and the transparent adhesive layer 102 does not soften. Therefore, as illustrated in FIG. 3D, the transparent beads 105 are buried in the colored adhesive layer 103, but the transparent adhesive layer 10
2, the colored adhesive layer 103 pressed by the transparent beads 105 is pushed out from the light emitting side of the transparent beads 105 without being pushed into the transparent adhesive layer 102. Thereafter, the temperature is further raised to 130 ° C. and maintained for 20 minutes.
When the temperature is increased to 130 ° C., the transparent adhesive layer 102 is also softened, and the transparent beads 105 are also buried in the transparent adhesive layer 102. For this reason, since the colored adhesive layer 103 is further pushed out from the vicinity of the light emitting side of the transparent beads 105 together with the transparent adhesive layer 102, the colored adhesive layer 103 wraps around the light emitting side of the transparent beads 105, and almost remains. Disappears. Thereafter, the transparent adhesive layer 102 and the colored adhesive layer 103 are solidified by cooling to room temperature, and the transparent beads 105 are fixed. The thickness of the hot melt adhesive layer 104 after fixing the transparent beads 105 was about 21 μm, and 58% of the diameter of the transparent beads 105 was exposed.

When this light distribution control element was evaluated, an isotropic viewing angle of ± about 50 ° in both the horizontal and vertical directions (here, an angle which is half the front luminance) was obtained. Further, the total light transmittance was higher than the theoretical value (the transmittance obtained when the light distribution control element could be ideally configured) by 95% or more.

It should be noted that the present invention is not limited to the materials and manufacturing methods described in this embodiment. That is, in the light distribution control element of the present embodiment, it is important that the softening or melting temperature of the transparent adhesive layer 102 is higher than the softening or melting temperature of the colored adhesive layer 103, and if this condition is satisfied, It is not limited to the above materials. Also, the transparent adhesive layer 1
02, and the temperature difference between the softening or melting temperature of the colored adhesive layer 103 and the colored adhesive layer 103
3 only softens or melts, while the transparent adhesive layer 10
2 is to ensure that the solidified or semi-solidified state is maintained.
Desirably, it is not less than 0 ⁰ C. Further, in the present embodiment, the heating temperature of the adhesive layer is set to two steps, but may be set to more steps or further to a continuous step. That is, during the manufacturing process, the light distribution control element of this embodiment
Only softens or melts, while the transparent adhesive layer 102
While the transparent beads 105 are buried in the colored adhesive layer 103 by keeping a solidified or semi-solidified state or a state having a higher viscosity than the colored adhesive layer, the transparent adhesive layer 102
Any kind of temperature control may be used as long as it can create a state that is not buried or hard to bury.

Next, as a second embodiment, the light distribution control element of this embodiment has the same optical action, properties, and shape as the light distribution control element shown in FIGS. It is the same. As shown in FIGS. 1 and 2, the light distribution control element of this embodiment includes a transparent base material 101, a hot melt adhesive layer 104 formed on the surface of the transparent base material 101, and the hot melt adhesive layer 104. And a plurality of microsphere-shaped transparent beads 105 fixed to the substrate. The components such as the transparent base material 101 and the transparent beads 105 are the same as those described in the first embodiment unless otherwise specified, and the description thereof will be omitted. The hot-melt adhesive layer 104 is composed of a transparent adhesive layer 102 and a colored adhesive layer 103, and the transparent adhesive layer 102 and the colored adhesive layer 103 are formed on a transparent substrate 101.
Are stacked in this order, which is also the same as that described in the first embodiment. However, in the light distribution control element of this embodiment, unlike the first embodiment, the softening or melting temperature of the transparent adhesive layer
It is desirable that the softening or melting temperature is higher,
It is not necessary to satisfy this. As described above, in the light distribution control element of this embodiment, only the colored adhesive layer 103 is softened or melted during the manufacturing process, while the transparent adhesive layer 102 is solidified or semi-solidified, or Keeping the viscosity higher than that of the adhesive layer, the transparent beads 105
Is buried in the colored adhesive layer 103, but the transparent adhesive layer 1
02 is characterized by passing through a state in which it is not buried or hardly buried. In the present embodiment, this state is realized by passing through a step of heating only the coloring adhesive layer 103 by electromagnetic wave (light) energy such as a laser beam or a flash lamp.

In this embodiment, a light distribution control element was manufactured as follows. First, a polyester hot melt transparent adhesive is applied to one surface of a flat transparent substrate 101 made of polyethylene terephthalate resin having a thickness of 120 μm by a knife coater so that the thickness after drying becomes 5 μm.
By drying with a dryer, the transparent adhesive layer 102 is formed and solidified. Next, a colored adhesive layer 103 obtained by mixing 10 parts by weight of carbon black with a polyester-based hot melt adhesive is formed thereon in the same manner as the transparent adhesive layer 102 so that the thickness after drying becomes 10 μm. Solidify.
Next, a refractive index of 1.935 (wavelength 589.3n)
m), spherical spherical transparent beads 1 having a diameter of 80 μm
05 are dispersed and arranged so as to have almost the maximum packing density. Next, the colored adhesive layer 103 is softened or melted by a pressure heating device illustrated in FIG.
5 is buried in the colored adhesive layer 103.

FIG. 4 is a schematic sectional view showing an example of a pressurizing and heating device used for manufacturing the light distribution control element of this embodiment. The pressurizing and heating apparatus includes a pressurizing plate 401 having a flat pressurizing section, and a transparent support made of a rigid body that is transparent to visible light and has sufficient strength, for example, a glass plate or a transparent resin plate. It comprises a plate 405 and an electromagnetic energy irradiation device 404. In this pressure heating device, the transparent substrate 101 side is supported by a transparent support plate 405, and the transparent beads 105 are pressed from the transparent beads 105 side to the transparent substrate 101 side by the pressure plate 401, and colored adhesion is performed by the electromagnetic wave energy irradiation device 404. The agent layer 103 is heated. The electromagnetic energy irradiation device 404 generates electromagnetic waves (light) in a wavelength region that is not absorbed by the transparent base material 101 and the transparent adhesive layer 102 but is absorbed by the colored adhesive layer 103. Xenon flash lamp 40
2, a reflector 403, a power supply (not shown), and a flash lamp device including a light emission control circuit. Since most of the flash wavelength of the xenon flash lamp 402 used here is in the visible light range, the electromagnetic energy of the flash is transmitted to the transparent support plate 405 and the transparent substrate 10.
1. It is not absorbed by the transparent adhesive layer 102, but is absorbed by the colored adhesive layer 103 containing carbon black and converted into heat. For this reason, strictly speaking, the temperature of a part of the transparent adhesive layer 103 rises due to heat conduction from the colored adhesive layer 103 which has become high temperature, but almost only the colored adhesive layer 103 rises in temperature and is softened or melted. You can get the status. Therefore, when the electromagnetic wave energy irradiation device 404 irradiates the transparent beads 105 with the pressure plate 401 and the transparent support plate 405 at a pressure of 4.5 kg / cm ² while applying the electromagnetic wave energy, first, only the temperature of the colored adhesive layer 103 increases. Although the transparent beads 105 are buried in the colored adhesive layer 103 because of softening or melting, the transparent adhesive layer 10
2 is a transparent adhesive layer 1 to maintain a solidified or semi-solidified state.
02 is not buried. Therefore, the state illustrated in FIG. 3D, that is, the transparent beads 105 are
, But hardly buried in the transparent adhesive layer 102,
A state where the colored adhesive layer 103 pressed by the transparent beads 105 is pushed out from the light emission side of the transparent beads 105 is obtained. Thereafter, the mixture is introduced into a constant temperature bath kept at a high temperature, and is kept at a temperature of 130 ° C. for 15 minutes while being pressed by a pressure plate 401. In the thermostat, the temperature of the transparent adhesive layer 102 is increased and softened mainly by heat transfer and heat conduction, so that the transparent beads 105 are also buried in the transparent adhesive layer 102. Therefore, the colored adhesive layer 1 near the light emitting side of the transparent beads 105
03 is further extruded together with the transparent adhesive layer 102,
The transparent adhesive 105 hardly wraps around the light emitting side of the colored adhesive layer 103 and remains. Thereafter, by cooling to normal temperature, the transparent adhesive layer 102 and the colored adhesive layer 103 are solidified, and the transparent beads 105 are fixed. According to this manufacturing method, the thickness of the hot melt adhesive layer 104 after embedding the transparent beads 105 is about 32 μm,
5 had about 60% of its diameter exposed.

When this light distribution control element was evaluated, an isotropic viewing angle of ± 50 ° in both the horizontal and vertical directions (an angle at which the luminance was に 対 し て of the front luminance) was obtained. As for the total light transmittance, a high transmittance of 95% or more with respect to the theoretical value (the transmittance obtained when the light distribution control element could be ideally configured) was obtained.

It should be noted that the materials, means,
The production method is not limited to this. For example, in this embodiment, a xenon flash lamp device is used as the electromagnetic wave energy irradiation device, but a solid-state laser such as a YAG laser, a gas laser, a semiconductor laser, or a lamp light source such as a halogen lamp or a metal halide lamp can be used. In addition, the wavelength region of the transparent substrate 1
01 and the transparent adhesive layer 102 are not limited to the visible wavelength region as long as the wavelength region is absorbed by the colored adhesive layer 103.

Next, as a third embodiment, the light distribution control element of the present embodiment is similar to the first embodiment in the light distribution control element shown in FIGS. It is the same. As shown in FIGS. 1 and 2, a light distribution control element according to the present embodiment includes a transparent base 101 and a transparent base 10.
It is composed of a hot melt adhesive layer 104 formed on one surface and a plurality of microsphere-shaped transparent beads 105 fixed to the hot melt adhesive layer 104. Transparent substrate 10
1. The components such as the transparent beads 105 and the like are the same as those described in the first embodiment unless otherwise specified, and thus the description thereof will be omitted. The hot melt adhesive layer 104 is composed of a transparent adhesive layer 102 and a colored adhesive layer 1 on a transparent substrate 101.
03 are stacked in this order, which is also the same as that described in the first embodiment. However, in the light distribution control element of this embodiment, unlike the first embodiment, the softening or melting temperature of the transparent adhesive layer 102 is different from that of the colored adhesive layer 10.
It is desirable that the softening temperature is higher than the melting temperature or the melting temperature, but it is not necessary to satisfy this. The feature of the light distribution control element of this embodiment is that the colored adhesive layer 103 has electrical conductivity. The conductivity of the colored adhesive layer 103 is realized by adding conductive fine particles to a hot melt adhesive serving as a base. Silver, as conductive fine particles,
Fine metal particles such as gold, copper, platinum, and nickel can be used. At this time, the surface of the fine metal particles is subjected to a lipophilic surface treatment such as a coupling agent such as a silicone coupling agent or a carboxylate or a phosphate ester in order to enhance the affinity between the base adhesive and the metal. It may be treated with an agent. In order not to affect the color of the colored adhesive layer 103,
A transparent conductive oxide such as tin oxide or indium oxide may be used as the conductive fine particles. Alternatively, the conductivity of the colored adhesive layer 103 may be realized by incorporating fine particles having both coloring properties and electrical conductivity, such as graphite, into the hot melt adhesive serving as a base. Here, as described above, the light distribution control element of the present embodiment
Only the colored adhesive layer 103 is softened or melted, while
The transparent adhesive layer 102 is kept in a solidified or semi-solidified state or has a higher viscosity than the colored adhesive layer, and the transparent beads 105 are buried in the colored adhesive layer 103, but are buried in the transparent adhesive layer 102. It is characterized by passing through a state in which it is not buried or hardly buried. In the light distribution control element of this embodiment, the coloring adhesive layer 103 is made conductive, a voltage is directly applied to the coloring adhesive layer 103, and only the coloring adhesive layer 103 is heated by Joule heat due to the resistance loss of the flowing current. By
This state is realized.

In this embodiment, a light distribution control element was manufactured as follows. First, a polyester hot melt transparent adhesive is applied to one surface of a flat transparent substrate 101 made of polyethylene terephthalate resin having a thickness of 120 μm by a knife coater so that the thickness after drying becomes 5 μm.
By drying with a dryer, the transparent adhesive layer 102 is formed and solidified. Next, 10 parts by weight of carbon black was added to the polyester-based hot melt adhesive, and 5 parts by weight of spherical or flaky silver fine particles having an average particle diameter of 500 nm or less were dried on the colored adhesive layer 103. It is formed and solidified by the same method as the transparent adhesive layer 102 so that the thickness afterwards becomes 10 μm. Next, a plurality of spherical transparent beads 105 made of glass having a refractive index of 1.935 (wavelength 589.3 nm) and a diameter of 80 μm are dispersed and arranged thereon so as to have almost the maximum packing density. Next, the colored adhesive layer 103 is softened or melted by the pressure heating device illustrated in FIG.
Buried in 03.

FIG. 5 is a schematic sectional view showing an example of a pressurizing and heating device used for manufacturing the light distribution control element of the present embodiment. This pressurizing and heating apparatus applies a voltage between the pressurizing plate 401 and the supporting plate 405 having flat pressing surfaces, electrodes 501 and 502 connected to both ends of the colored adhesive layer 103, and both electrodes. It comprises an AC power supply 503. This pressurizing and heating apparatus is configured to support the transparent base material 101 with a support plate 405 and to apply electric heating to the colored adhesive layer 103 while pressing the transparent beads 105 toward the transparent base material 101 side by the pressurizing plate 401. is there. Accordingly, the transparent beads 105 are pressed to the transparent substrate 101 side by a pressure of 4.5 by the pressure plate 401 and the support plate 405.
When a current is caused to flow through the colored adhesive layer 103 while applying a pressure of kg / cm ² , the temperature of the colored adhesive layer 103 rises due to heat generated by resistance loss of the flowing current, and the color adhesive layer 103 is softened or melted. At this time, strictly, a part of the transparent adhesive layer 103 is heated and softened by heat conduction from the colored adhesive layer 103 which has become high temperature, but generally only the colored adhesive layer 103 is heated, A softened or molten state can be obtained. For this reason, the transparent beads 105 are
However, the transparent adhesive layer 102 is not buried in the transparent adhesive layer 102 because the transparent adhesive layer 102 maintains a solidified or semi-solidified state. Therefore, the state illustrated in FIG. 3D, that is, the transparent beads 105 are buried in the colored adhesive layer 103, but hardly buried in the transparent adhesive layer 102, and the transparent beads 10
5, a state where the colored adhesive layer 103 pushed out from the light emitting side of the transparent beads 105 is obtained. Thereafter, the transparent beads 105 are introduced into a thermostat kept at a high temperature, and are held at a temperature of 130 ° C. for 15 minutes while the transparent beads 105 are pressed toward the transparent substrate 101 by the pressure plate 401 and the support plate 405. In the thermostatic oven, the temperature of the transparent adhesive layer 102 is increased mainly by heat transfer and heat conduction, and the transparent adhesive layer 102 is softened or melted, so that the transparent beads 105 are embedded in the transparent adhesive layer 102. At this time, the colored adhesive layer 1 near the light emitting side of the transparent beads 105
03 is further extruded together with the transparent adhesive layer 102,
The transparent adhesive 105 hardly wraps around the light emitting side of the colored adhesive layer 103 and remains. Thereafter, by cooling to normal temperature, the transparent adhesive layer 102 and the colored adhesive layer 103 are solidified, and the transparent beads 105 are fixed. According to this manufacturing method, the thickness of the hot melt adhesive layer 104 after embedding the transparent beads 105 is about 32 μm.
05 had about 60% of its diameter exposed.

When this light distribution control element was evaluated, an isotropic viewing angle of ± 50 ° in both the horizontal direction and the vertical direction (an angle at which half the front luminance was obtained) was obtained. As for the total light transmittance, a high transmittance of 95% or more with respect to the theoretical value (the transmittance obtained when the light distribution control element could be ideally configured) was obtained.

The light distribution control element of this embodiment can have an electromagnetic shielding effect due to the conductivity of the colored adhesive layer 103. Generally, the electromagnetic wave shielding effect of the conductive layer is expressed by the following equation (1). S (dB) = 50 + 10log (1 / ρf) + 1.7t√ (f / ρ) (1) where, S (dB); electromagnetic shielding effect ρ (Ω · cm); volume resistivity of the conductive layer f (MHz); electromagnetic wave frequency t (cm); layer thickness of conductive layer That is, if the volume specific resistance value of the colored adhesive layer 103 is reduced as much as possible, or if the layer thickness is increased, electromagnetic waves of a wide range of frequencies can be obtained. On the other hand, a larger shielding effect can be obtained. Therefore, the cutoff should be performed by adjusting the material and amount of the conductive fine particles contained in the colored adhesive layer, and changing the volume specific resistance value of the colored adhesive layer 103, or changing the layer thickness of the colored adhesive layer 103. The colored adhesive layer 103 corresponding to the frequency of the electromagnetic wave can be designed. If the electromagnetic wave shielding effect is designed to satisfy S> 30, an effective electromagnetic wave shielding effect can be obtained. Further, in this embodiment, a voltage is directly applied to the conductive colored adhesive layer 103 from the electrodes provided at both ends thereof, and the colored adhesive layer 103 is heated by resistance loss of a flowing current. What is called "induction heating" may be performed in which heating is performed by the generated eddy current.

Next, as a fourth embodiment, the light distribution control element of the present embodiment has optical functions, properties, and shapes similar to those of the light distribution control elements shown in FIGS. It is the same. As shown in FIGS. 1 and 2, the light distribution control element of this embodiment includes a transparent base material 101, a hot melt adhesive layer 104 formed on the surface of the transparent base material 101, and the hot melt adhesive layer 104. And a plurality of microsphere-shaped transparent beads 105 fixed to the substrate. The components such as the transparent base material 101 and the transparent beads 105 are the same as those described in the first embodiment unless otherwise specified, and the description thereof will be omitted. The hot melt adhesive layer 104 has a configuration in which a transparent adhesive layer 102 and a colored adhesive layer 103 are laminated on a transparent substrate 101 in this order, and this is also the same as that described in the first embodiment. . However, in the light distribution control element of the present embodiment, unlike the first embodiment, the transparent adhesive layer 10
It is desirable that the softening or melting temperature of No. 2 is higher than the softening or melting temperature of the colored adhesive layer 103, but it is not necessary to satisfy this. The feature of the light distribution control element of this embodiment is that the colored adhesive layer 103 contains magnetic powder. Here, in the light distribution control element of this embodiment, as described above, only the colored adhesive layer 103 of the hot melt adhesive layer 104 is softened or melted temporarily during the manufacturing process, and the transparent beads 105 are colored and adhered. The transparent adhesive layer 102 of the hot melt adhesive layer 104 is solidified or semi-solidified, or has a higher viscosity than the colored adhesive layer 103. In the light distribution control element of this embodiment, this state is realized by heating the colored adhesive layer 103 containing fine particles of a magnetic substance that absorbs electromagnetic energy by high-frequency induction heating during the manufacturing process.

In this embodiment, a light distribution control element was manufactured as follows. First, a polyester hot melt transparent adhesive is applied to one surface of a flat transparent substrate 101 made of polyethylene terephthalate resin having a thickness of 120 μm by a knife coater so that the thickness after drying becomes 5 μm.
By drying with a dryer, the transparent adhesive layer 102 is formed and solidified. Next, on top of this, 5 parts by weight of carbon black is blended with a polyester-based hot melt adhesive, and 10 parts by weight of manganese / zinc ferrite fine particles are further blended so that the color adhesive layer 103 after drying has a thickness of 10 μm. Is formed and solidified in the same manner as the transparent adhesive layer 102. Next, a refractive index of 1.935 (wavelength 58
9.3 nm) and a plurality of spherical transparent beads 105 made of glass having a diameter of 80 μm are dispersed and arranged so as to have almost the maximum packing density. Next, the colored adhesive layer 103 is softened or melted by the pressurizing and heating device illustrated in FIG. 6, and the transparent beads 105 are embedded in the colored adhesive layer 103.

FIG. 6 is a schematic sectional view showing an example of a pressurizing and heating device used for manufacturing the light distribution control element of this embodiment. This pressurizing and heating device includes a high-frequency power source 6 for generating a high-frequency current.
01, a high-frequency induction coil 602 connected thereto,
It is composed of a high-frequency induction coil holding member 603, a pressing plate 401 having a flat pressing portion, and a supporting plate 405 made of a material that easily transmits electromagnetic waves, for example, resin or glass. This pressurizing and heating device operates as follows. The transparent substrate 101 side is supported by a support plate 405, and the transparent beads 1
While applying a pressure to the transparent substrate 101 by the pressure plate 401, a current of a predetermined frequency is applied from the high frequency power supply 601 to the high frequency induction coil 602 disposed on the back of the support plate 405 for a predetermined time. When a high-frequency current is applied to the high-frequency induction coil 602, the magnetic fine particles contained in the colored adhesive layer 103 generate heat due to magnetic hysteresis loss. That is, the magnetic fine particles generate heat due to the high-frequency induction heating, so that the temperature of the colored adhesive layer 103 rises and is softened or melted. At this time, strictly, a part of the transparent adhesive layer 103 rises in temperature due to the heat conduction from the colored adhesive layer 103 which has become high temperature, but almost only the colored adhesive layer 103 rises in temperature and is softened or melted. You can get the status. Therefore, the transparent beads 105 are buried in the colored adhesive layer 103, but are not buried in the transparent adhesive layer 102 because the transparent adhesive layer 102 keeps a solid or semi-solid state. Therefore,
The state illustrated in FIG. 3D, that is, the transparent beads 105
Is buried in the colored adhesive layer 103, but the transparent adhesive layer 1
02, the colored adhesive layer 103 pressed by the transparent beads 105 is almost pushed out from the light emitting side of the transparent beads 105. Specifically, the pressing plate 40
A high-frequency current is applied to the high-frequency induction coil 602 from the high-frequency power supply 601 at a frequency of 800 kHz and 2 KW for 5 minutes while the transparent beads 105 are pressed toward the transparent substrate 101 at a pressure of 4.5 kg / cm ² by the support plate 1 and the support plate 405. Then, the transparent beads 1 are pressed by the pressure plate 401 and the support plate 405.
While pressurizing 05 toward the transparent base material 101, it is introduced into a thermostat kept at a high temperature, and kept at a temperature of 130 ° C. for 15 minutes.
In the thermostatic oven, the temperature of the transparent adhesive layer 102 also rises mainly due to heat transfer and heat conduction, and the transparent beads 105 are buried in the transparent adhesive layer 102 because they are softened or melted. At this time, the colored adhesive layer 1 near the light emitting side of the transparent beads 105
03 is further extruded from the vicinity of the light emitting side together with the transparent adhesive layer 102, and the transparent adhesive 105 hardly goes around the light emitting side of the colored adhesive layer 103 and remains.
Thereafter, the transparent adhesive layer 102 is cooled to room temperature.
The colored adhesive layer 103 is solidified, and the transparent beads 105 are fixed. According to this manufacturing method, the thickness of the hot melt adhesive layer 104 after embedding the transparent beads 105 was about 32 μm, and about 60% of the diameter of the transparent beads 105 was exposed.

When this light distribution control element was evaluated, an isotropic viewing angle of ± 50 ° in both the horizontal and vertical directions (an angle at which half the front luminance was obtained) was obtained. As for the total light transmittance, a high transmittance of 95% or more with respect to the theoretical value (the transmittance obtained when the light distribution control element could be ideally configured) was obtained.

In the light distribution control element of this embodiment, a high-frequency current is passed through the high-frequency induction coil, and the colored adhesive layer 103 containing a magnetic material is heated by electromagnetic induction.
The coloring adhesive layer 103 may contain minute metal fibers such as stainless steel and brass, in addition to the magnetic substance, to utilize heat generated by these iron losses. As described above, during the manufacturing process, the light distribution control element of
03 alone softens or melts, while the transparent adhesive layer 1
02 is a solidified or semi-solidified state or a state in which the viscosity is higher than that of the colored adhesive layer, and the transparent beads 105 are buried in the colored adhesive layer 103, but the transparent adhesive layer 102
It is important to go through a state that is not buried or almost buried. One of the methods for creating this state is to raise the temperature of the transparent adhesive layer 102 without increasing the temperature of the transparent adhesive layer 102 so much.
That is, only the temperature of 03 is increased. Any method can be used to achieve this. Therefore, in addition to the method described in the present embodiment, for example, a method using dielectric heating by microwaves may be used. As a method for creating the above state, it is also effective to change the physical properties of the adhesive itself, in addition to increasing the temperature of the colored adhesive layer 103 alone. In Example 1, this was realized by softening the transparent adhesive layer or setting the melting temperature higher than the softening or melting temperature of the colored adhesive layer. In addition, the transparent adhesive layer 102 may be formed by increasing the molecular weight of the resin serving as the base of the adhesive.
Is higher than the melt viscosity of the colored adhesive layer 103, the above state can be realized. In addition, by applying an antireflection film to each interface such as the light incident surface of the transparent beads 105 and the light emitting surface of the transparent base material 101, the transmittance of the light distribution control element of the present embodiment may be improved. Needless to say.

Next, a rear projection type display device using a light distribution control element according to an embodiment of the present invention will be described. FIG.
FIG. 1 is a schematic cross-sectional view of a rear projection display device of the present invention. As shown in FIG. 7, the rear projection display device of the present invention includes a projection device 701, a mirror 702, and a transmission screen 703, and projection light 704 emitted from the projection device 701 is transmitted through the mirror 702 to the transmission screen 703. And an image is displayed. As the projection device 701, a liquid crystal projector can be used. FIG. 9 is a schematic sectional view showing an example of the liquid crystal projector. LCD projectors
A light source 812, liquid crystal display devices 807, 808, 809 as two-dimensional optical switch devices, color separation dichroic mirrors 802, 803, a color combining cross dichroic prism 811, and total reflection mirrors 804, 805, 8
06 and a projection lens 810. The white light emitted from the light source 801 is a color separation dichroic mirror 802
Then, the blue light (B) and the other light are separated, and the blue light (B) is reflected by the total reflection mirror 804 and reaches the liquid crystal display device 807. On the other hand, the color separation dichroic mirror 80
The light other than the blue light (B) reflected by 2 is separated into green light (G) and red light (R) by the color separation dichroic mirror 803, and the green light (G) reaches the liquid crystal display element 809. The red light (R) is reflected by the total reflection mirrors 805 and 806 and reaches the liquid crystal display device 808. Liquid crystal display device 80
7, 808 and 809, a nematic having a positive dielectric anisotropy between a first transparent substrate having a transparent electrode and a second transparent substrate having a transparent electrode, a wiring, a switching element and the like forming a pixel. A so-called TN (Twisted Nematic) liquid crystal panel in which a liquid crystal is sealed and the long axis of the liquid crystal molecule is continuously twisted by 90 ° between two glass substrates, and a linearly polarized light orthogonal to a light incidence surface and a light emission surface. A TN liquid crystal display device including a polarizer and an analyzer arranged to transmit light is used. Liquid crystal display device 80
7, 808, and 809 spatially modulate the incident color light according to the respective image information and emit the light. Each color light modulated by the liquid crystal display device is synthesized by a color synthesizing cross dichroic prism 811, passes through a projection lens 810 as projection light 704, passes through a mirror 702 and passes through a transmission screen 7.
03 is projected.

As shown in FIG. 8, the transmission screen 703 includes a Fresnel lens sheet 801 and a light distribution control element 1.
00. The Fresnel lens 801 is an optical component having the same function as a convex lens, and parallelizes the diffused projection light 701 emitted from the projection device 701 to convert the incident angle of light incident on the light distribution control element 100 to 0 degree or its vicinity. Work. Here, the light distribution control element 100 shown in FIG. 1 and FIG. 2 has such a property that the transmittance decreases as the incident angle increases due to its configuration. FIG. 10 is a schematic diagram for explaining a decrease in transmittance due to an increase in the incident angle. As shown in FIG. 10, when the incident angle θ of the light increases, the incident light cannot pass through the opening of the light distribution control element 100, that is, the contact portion between the transparent beads 105 and the transparent adhesive layer 102. Therefore, when the incident angle θ increases, the incident light 106 is absorbed by the colored adhesive layer 103,
Furthermore, the interface reflection between the transparent substrate 101 and the air increases, so that the transmittance significantly decreases. FIG. 11 is a diagram illustrating an example of the relationship between the incident angle of light of the light distribution control element 100 and the transmittance. The horizontal axis is the light incident angle θ, and the vertical axis is the vertical incidence (θ
= 0 °) is 1 and the relative transmittance is 1.
When the incident angle θ exceeds 10 °, the transmittance is significantly reduced. Therefore, the spread of the light incident on the light distribution control element 100 is preferably as small as possible, but practically, the half-value angle may be within ± 10 °. By arranging the Fresnel lens 801 on the light incident side of the light distribution control element 100 as described above, the divergent projection light 70 from the projection device 701 can be obtained.
4 is parallelized to convert the incident angle of light incident on the light distribution control element 100 to 0 degree or its vicinity, since there is an effect of suppressing a decrease in transmittance of the light distribution control element 100, The brightness of the projection display image can be improved.

When the rear projection type display device having the above configuration was evaluated, a wide and isotropic viewing angle of ± 50 ° in both the horizontal direction and the vertical direction (an angle which is 輝 度 of the front luminance) was obtained. Was done. Furthermore, frontal brightness is 20% higher than before
It became bright. In addition, since unnecessary light incident on the transmission screen from the outside is absorbed by the colored adhesive layer of the light distribution control element, in a bright environment (vertical illuminance 300 lx),
A black display with a low luminance of 0.5 cd / m ² was realized. As described above, the rear projection display device of the present embodiment includes the transmissive screen 703 including the light distribution control element 100 and the Fresnel lens 801 disposed on the light incident side thereof. Therefore, when the divergent projection light 704 from the projection device 701 is incident on the light distribution control element 100, it is collimated by the Fresnel lens 801 and its incident angle is converted to 0 degree or its vicinity. In this case, there is an effect that the transmittance is reduced and the brightness of the displayed image is improved. Further, the light distribution control element 100 has a bright and isotropic viewing angle characteristic from any angle, and has a high effect of reducing stray light due to unnecessary external light. For this reason, a high-luminance, wide-viewing angle, and low-luminance black display even under a bright environment can be realized, so that a rear-projection display device with a high contrast ratio can be realized. In addition, by using the light distribution control element having an electromagnetic shielding function by containing conductive fine particles in the colored adhesive layer for a transmission screen member, low EMI (Ele) is obtained.
ctromagnetic Interferenc
e) Another effect is that a rear projection display device can be realized.

Next, a liquid crystal display device using a light distribution control element according to another embodiment of the present invention will be described. FIG. 12 is a schematic sectional view of the liquid crystal display device of the present invention. The liquid crystal display device of the present invention includes a liquid crystal panel 1302, a backlight device 1301 provided on the back surface thereof, and a liquid crystal panel 1302.
And a light distribution control element 100 of the present invention provided on the front surface of the analyzer 1214. The backlight device 1301 used here can efficiently emit substantially parallel light.
No. 12, and International Publication No. WO95 / 14255, “Backlight Assembly for Electro-Optical Display” can be used. Here, a backlight device including a light source 1201 composed of a cold cathode tube, a light guide 1202 composed of a transparent acrylic resin, and a light collimating means 1203 was used. As the light collimating means 1203, a known element can be used.
A quadrangular pyramid-shaped micro-tapered rod array optically coupled to the light guide 1202 shown in FIG.
In this case, the light guided from the light guide 1202 causes one or more total reflections on the wall surface of the micro-tapered rod, and is emitted after being made substantially parallel. Light collimating means 1203
Alternatively, a micro prism sheet or a micro lens array can be used. By using such a backlight device, substantially collimated illumination light within a half-value angle of ± 10 ° can be obtained. The liquid crystal panel 1302
Transparent electrode 1212 made of TO (Indium Tin Oxide) and light distribution film 1 made of polyimide polymer
A first transparent substrate 1210 having a light-transmitting film 211;
07, a transparent electrode 1206 forming a pixel, a second transparent substrate 1205 having a switching element such as a wiring and a thin film transistor (not shown) connected thereto, and two transparent substrates 1205 connected via a sealant 1208.
And a liquid crystal layer 1209 made of a nematic liquid crystal having a positive dielectric anisotropy enclosed between 1210. This liquid crystal panel has light distribution films 1207 and 12 formed on two transparent substrates.
11 is subjected to a rubbing treatment, whereby the long axis of the liquid crystal molecules of the liquid crystal layer 1209 is continuously twisted by 90 ° between the two transparent substrates, that is, a so-called TN (Twisted Nematic).
It constitutes a liquid crystal panel. A polarizer 1204 and an analyzer 1214 are arranged on a light incident surface and a light exit surface of the liquid crystal panel 1302 so as to transmit linearly polarized light orthogonal to each other. As the polarizer 1204 and the analyzer 1214, a film obtained by absorbing iodine into a stretched polyvinyl alcohol to give a polarizing function and having a TAC (triacetyl cellulose) protective layer on both surfaces is used. It is bonded to the substrate 1210 by an acrylic adhesive so as to be optically bonded. Analyzer 1
The light distribution control element 100 is arranged on the front of 214. Here, the bonding between the light distribution control element 100 and the analyzer 1214 is performed by using an adhesive 12 patterned so as to surround the display unit.
13, the gap between the transparent beads of the light distribution control element 100 and the analyzer 1214 may be adhered so as to cover the entire surface with a transparent adhesive having a low refractive index. They may be used in combination.

Next, the operation of the direct-view type liquid crystal display device will be described. Light 12 emitted from backlight device 1301
Among 15, the linearly polarized light transmitted through the polarizer 1204 is transmitted through the liquid crystal panel 1302 and enters the analyzer 1214.
At this time, since the polarization state of light transmitted through the liquid crystal panel 1302 changes according to the voltage applied to the liquid crystal layer 1209, the amount of light transmitted through the analyzer 1214 is obtained by applying a voltage corresponding to image information to the liquid crystal layer 1209. Can be controlled to form an image. The image light transmitted through the analyzer 1214 enters the light distribution control element 100. Most of the light incident on the light distribution control element 100 is incident on the transparent beads of the light distribution control element 100, and is condensed by the refraction action and isotropically diffused. Here, a general TN liquid crystal display device has a viewing angle dependency, and when observed from an oblique direction, a decrease in contrast ratio, gradation inversion, and color tone change occur. Therefore,
Good image quality is obtained only in a limited area near the front. As described above, when the incident angle of the incident light is large, the light distribution control element 100 has a low transmittance due to absorption by the colored adhesive layer. Therefore, of the light emitted from the liquid crystal panel 1302, the contrast ratio is reduced, the gradation is inverted,
Light having a large incident angle at which a color tone change occurs is mostly absorbed by the colored adhesive layer of the light distribution control element 100. On the other hand, light near the front where good image quality is obtained, that is, light near the incident angle of 0 ° is transmitted and isotropically diffused, so that there is no color tone change or gradation inversion over a wide viewing angle range, and the contrast ratio is high. An image is obtained. Further, the backlight device 1
Since the light emitted from 301 to the liquid crystal panel 1302 is substantially parallel light, the ratio of the amount of light in the angle range where good image quality can be obtained in the liquid crystal panel increases, and at the same time, the light loss in the light distribution control element 100 decreases. As a result, the light use efficiency increases, so that a high-luminance image can be obtained.

Therefore, in the liquid crystal display device of the present embodiment,
High brightness, no color change or gradation inversion over a wide viewing angle range
There is an effect that a high-contrast image can be obtained. Further, since the light distribution control element 100 has a high effect of reducing stray light due to unnecessary external light, a black display with low luminance is realized even in a bright environment, and an image with a high contrast ratio is obtained. When the liquid crystal display device having the above configuration was evaluated, there was no color tone change or gradation inversion within a viewing angle range of ± 80 °, and an isotropic and wide viewing angle having a contrast ratio of 100: 1 or more was obtained.

Although a TN liquid crystal panel for monochrome display has been described as an example of the liquid crystal panel, a liquid crystal panel for full color display may be provided by applying a micro color filter to a transparent substrate. Further, the display mode is not limited to the TN mode, but may be a VA (Vertical aligned) mode or an ECB (Electrically Controlled) mode.
old birefringence mode, O
CB (Optically Compensated)
Bend) mode, STN (Super Twiste)
A liquid crystal panel of another mode such as a (d Nematic) mode may be used. Further, the driving method may be not only active matrix driving with a switching element such as a thin film transistor but also direct matrix driving.

[0035]

As described above, according to the present invention,
The hot melt adhesive layer of the light distribution control element is laminated on the transparent substrate in the order of the transparent adhesive layer and the colored adhesive layer, and the softening temperature or the melting temperature or the melt viscosity is higher than the colored adhesive layer. By doing so, since the colored adhesive layer wraps around the light emitting side of the transparent beads, and there is no residue,
Light incident on the transparent beads passes through without being absorbed,
High transmittance can be obtained. Therefore, it is possible to obtain a light distribution control element that has a high effect of reducing stray light due to external unnecessary light in a bright environment, is bright even when viewed from any angle by an observer, and has isotropic viewing angle characteristics. In addition, by blending a material in which the softening temperature or the melting temperature or the melt viscosity of the colored adhesive layer containing the coloring material is lower than that of the transparent adhesive layer, the softening temperature or the melting temperature or the melt viscosity of the colored adhesive layer containing the coloring material is changed. A transparent adhesive layer higher than the agent layer can be easily formed. In addition, by blending conductive fine particles or magnetic powder into the colored adhesive layer, a transparent adhesive layer having a higher melting temperature or melt viscosity than the colored adhesive layer can be easily formed. In addition, by including an appropriate amount of conductive fine particles in the colored adhesive layer, an electromagnetic shielding effect can be obtained on the entire surface of the light distribution control element. Further, during the manufacturing process, the light distribution control element of the present invention softens or melts only the colored adhesive layer while pressing the transparent beads toward the transparent substrate, while the transparent adhesive layer is In order to keep the solidified or semi-solidified state or the viscosity higher than the colored adhesive layer, the transparent beads are buried in the colored adhesive layer, but are not buried in the transparent adhesive layer or hardly buried. Without pushing the colored adhesive layer pressed by the transparent beads into the transparent adhesive layer, most of it is extruded from the light emitting surface of the transparent beads, and then the transparent adhesive layer is softened or melted, and the transparent beads are transparently bonded. When buried in the agent layer, the colored adhesive layer near the light emitting side of the transparent beads is further extruded together with the transparent adhesive layer, so that the colored adhesive layer is prevented from wrapping around the light emitting side of the transparent beads and remaining. so That. In addition, by configuring the transmission type screen of the rear projection display device using the light distribution control element and the Fresnel lens, when the divergent projection light from the projection device enters the light distribution control element, it is collimated by the Fresnel lens. Since the incident angle is converted to 0 degree or its vicinity, a decrease in transmittance in the light distribution control element can be suppressed, and the brightness of a display image can be improved. In addition, the light distribution control element constituting the transmissive screen has a bright and isotropic viewing angle characteristic from any angle, and has a high effect of reducing stray light due to external unnecessary light. By realizing a low-luminance black display even at a corner or in a bright environment, a rear-projection display device with a high contrast ratio can be realized. In addition, by using a light distribution control element having an electromagnetic shielding function by including conductive fine particles in a colored adhesive layer for a transmission screen member, low EMI (Electromagnetic) can be achieved.
It is possible to realize a rear-projection display device of an interference (Interference) type. In addition, by providing a backlight device that emits light substantially parallel to the liquid crystal display device, and further including a light distribution control element on the light emission surface of the liquid crystal panel, the light distribution control element increases the incident angle of incident light. Since the transmittance is reduced due to absorption in the colored adhesive layer, of the light emitted from the liquid crystal panel, light having a large incident angle that causes a decrease in contrast ratio, grayscale inversion, and color change occurs. The color adhesive layer absorbs most of the color, while transmitting light near the front where good image quality is obtained, that is, near the incident angle of 0 °, and isotropically diffuses, so that the color tone changes over a wide viewing angle range. An image having a high contrast ratio can be obtained without any grayscale inversion. In addition, since the light emitted from the backlight device to the liquid crystal panel is substantially parallel light, the light amount ratio in the angle range where good image quality can be obtained in the liquid crystal panel increases, and the light loss in the light distribution control element also decreases. Since the light utilization efficiency is increased by reducing the luminance, a high-luminance image can be obtained. Therefore, the liquid crystal display device of the present invention can obtain a high-brightness, high-contrast image without color tone change or gradation inversion over a wide viewing angle range.

[Brief description of the drawings]

FIG. 1 is a partial schematic cross-sectional view of a light distribution control element according to an embodiment of the present invention.

FIG. 2 is a partial schematic perspective view of a light distribution control element according to an embodiment of the present invention.

FIG. 3 is an embodiment of a method of manufacturing a light distribution control element used in the display device of the present invention.

FIG. 4 is a heating and pressurizing apparatus for manufacturing the light distribution control element of the present invention.

FIG. 5 is a heating and pressurizing apparatus for manufacturing the light distribution control element of the present invention.

FIG. 6 is a heating and pressurizing apparatus for manufacturing the light distribution control element of the present invention.

FIG. 7 is a schematic sectional view of a rear projection type display device according to an embodiment of the present invention.

FIG. 8 is a schematic cross-sectional view of a transmission screen of a rear projection display according to an embodiment of the display of the present invention.

FIG. 9 is a schematic sectional view of a projection device of a rear projection type display device according to an embodiment of the present invention.

FIG. 10 is a diagram for explaining the light incident angle dependence of the transmittance of the light distribution control element of the present invention.

FIG. 11 is a diagram showing the relationship between the transmittance and the incident angle of the light distribution control element of the present invention.

FIG. 12 is a schematic sectional view of a liquid crystal display device according to another embodiment of the display device of the present invention.

FIG. 13 is a schematic sectional view showing a conventional transmission screen.

FIG. 14 is a partial cross-sectional view showing a lenticular lens sheet.

FIG. 15 is a partial perspective view showing a lenticular lens sheet.

FIG. 16 is a partial perspective view showing a conventional transmission screen.

FIG. 17 is a view for explaining a residual colored adhesive which is a problem of the conventional light distribution control element.

[Explanation of symbols]

Reference Signs List 100 light distribution control element, 101 transparent substrate, 102 transparent adhesive layer, 103 colored adhesive layer, 104 hot melt adhesive layer, 105 transparent beads, 401 pressing means, 404 electromagnetic wave energy Irradiation device, 405 support means, 501, 502 electrodes, 503 power supply, 601
High frequency power supply, 602: High frequency induction coil, 701: Projection device, 702: Mirror, 703: Transmission screen, 8
01: Fresnel lens sheet, 1301: backlight device, 1302: liquid crystal panel

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Ikuo Hiyama 7-1-1, Omikacho, Hitachi City, Ibaraki Prefecture Inside Hitachi, Ltd. Hitachi Research Laboratory, Ltd. (72) Inventor Tetsuro Minemura 7-1 Omikacho, Hitachi City, Ibaraki Prefecture No.1 F-term in Hitachi, Ltd. Hitachi Research Laboratory F-term (reference) FA50X FB02 FB07 FB12 FB13 FC18 GA13 HA07 LA17 MA07 4F213 AA21E AB18 AD04 AH81 WA15 WA53 WA97 WB01

Claims (12)

[Claims] An arrangement comprising a transparent base material, a hot-melt adhesive layer formed on the transparent base material, and one microsphere-shaped transparent beads embedded in the hot-melt adhesive layer. In the light control element, the hot melt adhesive layer has a transparent adhesive layer and a colored adhesive layer laminated on the transparent substrate in this order, and has a softening temperature or a melting temperature or a melt viscosity higher than that of the colored adhesive layer. A light distribution control element having a high transparent adhesive layer. 2. The coloring adhesive layer according to claim 1, wherein the coloring adhesive layer contains a material having a softening temperature, a melting temperature, or a melting viscosity lower than that of the transparent adhesive layer. Light distribution control element. 3. The light distribution control element according to claim 1, wherein conductive fine particles or magnetic powder is blended into the colored adhesive layer. 4. A transparent base material, a hot melt adhesive layer formed on the transparent base material and comprising a transparent adhesive layer and a colored adhesive layer, and a single layer embedded in the hot melt adhesive layer. In a method for manufacturing a light distribution control element composed of microsphere-shaped transparent beads, a step of laminating and forming the transparent adhesive layer and the colored adhesive layer on the transparent substrate; Temporarily solidifying or semi-solidifying the adhesive layer, dispersing and disposing the transparent beads on the colored adhesive layer, and pressing the transparent beads toward the transparent substrate, Heating the transparent adhesive layer, softening or melting to push the transparent beads into the colored adhesive layer and the transparent adhesive layer, and the temperature of the transparent adhesive layer and the colored adhesive layer Lower and solidify Fixing the transparent beads, and furthermore, in that step, only the colored adhesive layer is softened or melted, while the transparent adhesive layer is in a solidified or semi-solidified state or more than the colored adhesive layer. A method for manufacturing a light distribution control element, wherein the transparent beads are buried in the colored adhesive layer and buried or hardly buried in the transparent adhesive layer while maintaining a high viscosity state. 5. A transparent base material, a hot melt adhesive layer formed on the transparent base material and comprising a transparent adhesive layer and a colored adhesive layer, and a single layer embedded in the hot melt adhesive layer. In a method for manufacturing a light distribution control element composed of microsphere-shaped transparent beads, a step of laminating and forming the transparent adhesive layer and the colored adhesive layer on the transparent substrate; A step of once solidifying or semi-solidifying the adhesive layer, a step of dispersing and disposing the transparent beads on the colored adhesive layer, and while pressing the transparent beads toward the transparent substrate, the transparent adhesive layer is Maintaining the softening temperature or the melting temperature or less, and heating only the coloring adhesive layer to the softening temperature or the melting temperature or more, softening or melting to bury the transparent beads in the coloring adhesive layer; Raising the temperature of the transparent adhesive layer and burying the beads in the transparent adhesive layer while pressing the beads toward the transparent substrate; and solidifying by lowering the temperatures of the transparent adhesive layer and the colored adhesive layer. And a step of fixing the transparent beads. 6. The method according to claim 4, wherein in the step of heating only the colored adhesive layer to a temperature higher than a softening temperature or a melting temperature, the colored adhesive layer absorbs and absorbs the transparent adhesive layer and the transparent adhesive layer. A method for manufacturing a light distribution control element, wherein electromagnetic wave energy not absorbed by a substrate is used. 7. The colored adhesive layer according to claim 4 or 5, wherein the colored adhesive layer contains conductive fine particles, and in the step of heating only the colored adhesive layer to a softening temperature or a melting temperature or higher. A method for manufacturing a light distribution control element, comprising applying a power supply voltage to a device and utilizing Joule heat due to resistance loss. 8. The colored adhesive layer according to claim 4, wherein the colored adhesive layer contains a magnetic powder, and in the step of heating only the colored adhesive layer to a softening temperature or a melting temperature or higher. A method for manufacturing a light distribution control element, comprising connecting a high frequency power supply and using high frequency induction heating. 9. A projection apparatus comprising: a light source; two-dimensional optical switch means for modulating light from the light source according to image information to form an optical image; and a projection lens for enlarging and projecting the optical image. A rear projection display device, comprising: a projection screen from which the light projected from the projection device is incident from the rear surface and a transmission screen for displaying the projection light on the front surface, wherein the transmission screen is provided on the incident side of the projection light. Means and a light distribution control element, the light distribution control element comprises a transparent substrate, a transparent adhesive layer and a colored adhesive layer laminated on the transparent substrate in this order, and a softening temperature or a melting temperature. Or a transparent adhesive layer having a higher melt viscosity than the colored adhesive layer. 10. A first transparent substrate on which a transparent electrode and a light distribution film are laminated and formed, a second transparent substrate on which a light distribution film and a transparent electrode are laminated and having a switching element, And a liquid crystal panel comprising a liquid crystal layer sandwiched between a second transparent substrate and a liquid crystal display device provided with a polarizer and an analyzer disposed on the back and front of the liquid crystal panel, respectively. A backlight device that emits substantially parallel light is arranged on the back surface, and a light distribution control element is arranged on the front surface of the analyzer, and the light distribution control element is a transparent substrate and a transparent substrate. A display device comprising: an adhesive layer and a colored adhesive layer laminated in this order; and a transparent adhesive layer having a softening temperature, a melting temperature, or a melt viscosity higher than that of the colored adhesive layer. 11. The method according to claim 9, wherein
A display device comprising: a material in which a softening temperature, a melting temperature, or a melt viscosity of the colored adhesive layer containing a coloring material is lower than that of the transparent adhesive layer. 12. The method according to claim 9, wherein
A display device, wherein conductive particles or magnetic powder is blended in the colored adhesive layer.