JP4249584B2 - Projection display - Google Patents

Description

  The present invention relates to a projection display device using a light distribution control element that can be used as a transmission screen member of a rear projection display device or a viewing angle widening member such as a liquid crystal display device.

  Since the rear projection display device can realize a large screen display relatively easily and in a small size and at a low cost as compared with the direct view type CRT, the demand is increasing mainly in the North American market. In particular, a rear projection type display device having a projection device using a liquid crystal display element such as a TN (Twisted Nematic) liquid crystal as a two-dimensional optical switch element is different from a rear projection type display device using a CRT projection tube. This enables high-definition display without blurring to the periphery of the screen, and is expected as a favorite of high-resolution digital television.

  FIG. 11 is a schematic cross-sectional view of a rear projection display device. The projection light 704 emitted from the projection device 701 is applied to the transmission screen 703 via the mirror 702, and an image is displayed on the front surface thereof.

  As shown in FIG. 38, the transmission screen 703 is generally composed of a Fresnel lens sheet 1402 and a lenticular lens sheet 1401, and the Fresnel lens sheet 1402 is an optical component that acts in the same manner as a convex lens. The direction of is bent toward the viewer side and works to widen the appropriate viewing range.

  The lenticular lens 1401 is intended to obtain a bright image by effectively distributing the limited projection light beam from the projection device 701 to the observation range of the observer.

  FIG. 36 is a schematic cross-sectional view showing an example of a lenticular lens, and FIG. 37 is a schematic perspective view of the lenticular lens.

  The lenticular lens 1401 has a configuration in which a plurality of cylindrical lens-like lenses 1501 are arranged in one direction and a black stripe 1502 is provided in a portion other than the light condensing portion, and the focal position of the lens 1501 is set as an observation surface of the screen. Therefore, ideally, there is no loss of projection light, and a reduction in contrast ratio with respect to external light can be suppressed.

  Generally, a lenticular lens is arranged such that its generatrix is arranged in a direction perpendicular to the display surface, so that a wide viewing angle can be obtained in the horizontal direction. Therefore, the light distribution in the vertical direction is only diffused in the base material of the lenticular lens or by the diffusing material blended in the surface portion, so that the viewing angle in the vertical direction is considerably narrower than in the horizontal direction. Further, since lenticular lenses are regularly arranged with linear lenses, moire interference fringes are likely to occur in the image.

  On the other hand, Patent Document 1 discloses a transmission screen having a configuration in which a spherical lens 1602 is spread on a transparent base material 1601 as shown in FIG. 39 and fixed with a transparent resin. In this configuration, since a mold is not used, there is no size limitation in manufacturing, and a seamless large screen transmissive screen can be realized. Furthermore, the light incident from the spherical lens side converges due to the lens effect of the spherical lens and diverges isotropically, so that a wide viewing angle can be obtained in both the horizontal and vertical directions.

  Furthermore, Non-Patent Document 1 discloses a screen having a structure in which optical beads are fixed onto a transparent substrate via a light-absorbing adhesive layer, and the surface of the optical beads opposite to the transparent substrate is transparently coated. ing.

  Patent Document 2 discloses a planar lens having a structure in which 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 these structures, the isotropic viewing angle can be obtained in a wide horizontal and vertical direction due to the lens effect of the beads, as in the above-mentioned Patent Document 2. Furthermore, since unnecessary light incident from the outside is absorbed by the light-absorbing adhesive layer (or colored hot-melt adhesive layer), a high contrast ratio can be obtained even in a bright environment. Moreover, high resolution can be realized relatively easily by reducing the diameter of the beads.

Japanese Patent Laid-Open No. 2-77736

JP 9-318801 A SID94 DIGEST pp741-744 (A Novel High-Resolution Ambient-Light-Rejecting Rear-ProjectionScreen)

  The conventional planar lens (hereinafter referred to as a light distribution control element) was produced as follows. A flat polyethylene terephthalate (PET) resin film having a thickness of 120 μm is used as a transparent substrate, a transparent adhesive layer made of a polyester-based hot melt adhesive is 5 μm on the surface, and the polyester-based hot-melt adhesive is carbon on the same. A colored adhesive layer containing 10 parts by weight of black is formed to have a thickness of 4.5 μm and is solidified once.

  Further, spherical glass beads having a refractive index of 1.935 (wavelength: 589.3 nm) and a diameter of 50 μm are densely dispersed, and the transparent adhesive layer and the colored adhesive layer are heated and softened in a thermostatic bath. Then, the transparent beads were pressed to the transparent substrate side with a pressure plate, embedded in the colored adhesive layer and the transparent adhesive layer, and fixed. The thickness of the adhesive layer after fixing was about 21 μm, including 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.

  The produced light distribution control element was evaluated as a transmissive screen of a rear projection display device provided with a projection device using a TN liquid crystal display element as a two-dimensional optical switch element (light valve). A wide viewing angle of ± 50 ° or more (here, an angle that is 1/2 of the front luminance) is obtained, and unnecessary light incident on the light distribution control element from the outside (observer side) is colored. Absorbed by the adhesive layer, a low-brightness black display was achieved even in a bright environment.

  However, when the image projected on the light distribution control element was observed from an oblique direction, it was found that a substantially concentric striped pattern appeared and the image quality was significantly deteriorated. Furthermore, it was also found that an undesirable chromaticity change occurs in an image when observed from an oblique direction.

  An object of the present invention is to provide a light distribution control element in which image quality is not deteriorated due to the occurrence of the stripe pattern, and a display device having a high luminance, a high contrast ratio, and a wide viewing angle using the light distribution control element. Other purposes will become apparent from the following description.

  The present inventors have conducted a more detailed study on the conventional light distribution control element described above in order to search for the cause of the stripe pattern and the chromaticity change. As a result, the stripe pattern is generated when polarized light enters the light distribution control element, and the optical anisotropy of the transparent base material causes different phase differences in light traveling at different angles in the base material. And it discovered that the difference of the energy transmittance of the p polarization | polarized-light component of the light radiate | emitted from a transparent base material, and an s-polarized light component combined occurred. Further, the present inventors have found that the light distribution characteristic of the present light distribution control element changes depending on the polarization state of incident light, which causes a change in chromaticity. The gist of the present invention achieved based on the above is as follows.

  [1] A light distribution provided with a transparent substrate, a large number of microlenses arranged densely on one surface of the transparent substrate, and a light absorption layer having a microopening at a substantially focal position of the microlens The light distribution control element according to claim 1, wherein the transparent substrate is made of an optically isotropic transparent body or a uniaxial optically anisotropic transparent body.

  By using this, the generation of a stripe pattern at the time of polarization incidence is eliminated by suppressing the generation of a phase difference that affects the image quality.

[2] In a rear projection type display device including a projection device that projects an optical image, and a transmissive screen on which projection light from the projection device is incident from the back and displays the light on the front surface,
The projection apparatus includes a single-tube projection apparatus having a light source, a two-dimensional optical switch element that modulates light from the light source into an optical image according to image information, and a projection lens that magnifies and projects the modulated optical image. ,
Polarization state alignment that substantially matches the polarization state of the optical image light formed by the two-dimensional optical switch element in the entire visible wavelength range when the modulated optical image emitted from the projection device is incident on the transmissive screen. Having means,
The transmissive screen includes a transparent substrate, a large number of microlenses arranged densely on one surface of the transparent substrate, and a light absorption layer having a microopening at a substantially focal position of the microlens. The transparent substrate is provided on the projection light incident side of the light distribution control element composed of an optically isotropic transparent body or a transparent body of uniaxial optical anisotropy. A rear projection display device comprising a light beam collimating means.

  As described above, the polarization state of the projection light (optical image light) incident on the light distribution control element is the same in the entire visible wavelength range. For this reason, coloring due to the polarization dependence of the light distribution characteristic of the light distribution control element does not occur, and high-quality display without chromaticity change can be realized even when observed from an oblique direction.

  Furthermore, since the image light incident on the light distribution control element is incident in a substantially parallel state and substantially at an incident angle of 0 °, a decrease in transmittance at the light distribution control element is suppressed, and a bright display image is displayed. can get.

  [3] The two-dimensional optical switch element is a two-dimensional optical switch element that performs display using polarized light, and the polarization direction of the optical image light formed by the two-dimensional optical switch element indicates the vibration direction of the electric vector as described above. The rear projection display device comprising a polarization state conversion means for converting the light into one of horizontal linearly polarized light, vertical linearly polarized light, circularly polarized light, and elliptically polarized light with respect to the transmissive screen display surface.

  As described above, since the polarization state of the optical image light incident on the light distribution control element can be controlled, the viewing angle characteristic can be adjusted by the polarization dependency of the light distribution characteristic of the light distribution control element without changing the configuration of the transmission screen. A rear projection display device that can be easily changed can be realized.

  [4] In the rear projection display device, an observer sensing unit that senses the presence or absence of an observer, and an observer position determination unit that cuts off the position of the observer in the horizontal and vertical directions based on a sensing signal of the observer sensing unit And the rear projection display device comprising control signal output means for outputting a control signal to the polarization state conversion element based on information from the observer position determination means.

  As described above, it is possible to automatically determine the position of the observer, and change the polarization state of the projection light based on this position information, thereby obtaining viewing angle characteristics corresponding to the position of the observer. In other words, the viewing angle characteristic is automatically changed according to the position of the observer, and the limited image light is effectively distributed in the direction of the observer to provide a good image to the observer.

[5] Single tube projection in which the projection device includes a light source, a two-dimensional optical switch element that modulates light from the light source into an optical image according to image information, and a projection lens that magnifies and projects the modulated optical image. Equipped with equipment,
The transmissive screen has a transparent substrate, a large number of microlenses arranged densely on one surface of the transparent substrate, and a light absorption layer having a microopening at a substantially focal position of the microlens. A light distribution control element, and a light beam collimating unit disposed on the incident light incident side of the light distribution control element,
A rear projection type display device comprising: a non-polarization means for making the projection light emitted from the projection device and incident on the transmission screen substantially non-polarized.

  As described above, since the optical image light incident on the light distribution control element constituting the transmissive screen is non-polarized light, the chromaticity change due to the polarization dependence of the light distribution characteristic of the light distribution control element does not occur. Further, since a stripe pattern generated at the time of polarized light incidence does not occur due to the optical anisotropy of the transparent base material of the light distribution control element, a beautiful image without image quality deterioration can be obtained. In addition, even if a transparent body having optical anisotropy is used as a transparent base material, there is no deterioration in image quality, so the selection range of the material is widened, and the transmission screen is made of a light distribution control element that is less expensive and has high strength. Can be realized.

[6] A pair of transparent substrates in which a transparent electrode and an alignment film are laminated, and the alignment film forming surfaces are opposed to each other and bonded with a certain gap, a liquid crystal layer sealed in the gap, and the transparent electrode In a liquid crystal display device in which a voltage applying means for applying a voltage corresponding to an image signal to the light input surface side and the light output surface side of the pair of transparent substrates is arranged with a polarizer and an analyzer,
A backlight device that emits light substantially parallel to the back of the pair of transparent substrates is disposed,
On the light exit surface side of the pair of transparent substrates, a transparent base material, a large number of microlenses arranged densely on one surface of the transparent base material, and a microscopic opening at a substantially focal position of the microlens A light distribution control element comprising a light absorbing layer having a transparent body that is optically substantially isotropic, or a transparent body having uniaxial optical anisotropy. Liquid crystal display device.

  As a result, only a limited range of light near the front where good image quality can be obtained can be diffused isotropically by the light distribution control element, so there is no color change or gradation inversion over a wide viewing angle range, A liquid crystal display device capable of obtaining an image with a high contrast ratio can be realized.

  [7] A polarizer is disposed on the light incident surfaces of the pair of transparent substrates, an analyzer and a light distribution control element are disposed in order from the transparent substrate side on the light exit surface, and a transmission axis of linearly polarized light of the analyzer is further provided. The liquid crystal display device in which is disposed in a horizontal direction with respect to the display surface.

  Thereby, the viewing angle in the horizontal direction is wider than the vertical direction with respect to the display surface due to the polarization dependence of the light distribution characteristic of the light distribution control element, and the limited light can be effectively distributed to the observer. .

  [8] A polarizer is disposed on the light incident surface of the pair of transparent substrates, an analyzer and a light distribution control element are disposed in this order from the transparent substrate side on the light exit surface, and the analyzer and the light distribution control element are further disposed. The liquid crystal display device in which a retardation plate is disposed between them.

  As a result, the polarization state of the light incident on the light distribution control element can be arbitrarily changed by the phase plate disposed between the analyzer and the light distribution control element. A desired viewing angle can be obtained by utilizing the polarization dependency of the light distribution characteristic.

  As described above, the light distribution control element of the present invention is substantially optically isotropic as a transparent substrate, or uses a uniaxially anisotropic transparent body having an optical axis in the plane so that polarized light is incident. However, the image quality is not deteriorated due to the generation of the stripe pattern, and a wide viewing angle can be obtained. Therefore, the light distribution control element of the present invention can be used as a viewing angle widening means of a display device using polarized light such as a liquid crystal display device.

  Further, the rear projection type display device of the present invention comprises the transmissive screen composed of the light distribution control element of the present invention and a Fresnel lens disposed on the light incident side of the projection light incident on the light distribution control element. By making the incident angle substantially 0 degrees, a decrease in transmittance at the light distribution control element is suppressed, and a bright display image is obtained. Furthermore, by using a single-tube projection device as the projection device, color shift and coloring caused by the light incident angle dependency of the light distribution control element do not occur, so that a high-quality image can be obtained.

  Further, in the rear projection type display device of the present invention, the coloration caused by the polarization dependency of the light distribution characteristic of the light distribution control element is eliminated by matching the polarization state of the projection light emitted from the projection device with each color light. High-quality images can be obtained.

  In addition, the light distribution control element has a bright and wide viewing angle characteristic when viewed from any angle, and is highly effective in reducing stray light caused by external unnecessary light. A ratio display can be realized.

  In the rear projection display device of the present invention, a substantially concentric minute lens is used as the minute lens of the light distribution control element, and a polarization state conversion element that can change the polarization state of the light projected on the transmission screen is provided. Thus, there is an effect that the viewing angle characteristics of the display device can be easily changed without changing the configuration of the screen.

  Further, an observer sensing unit that senses the presence or absence of an observer on the rear projection display device, an observer position judging means that judges the horizontal and vertical positions of the observer based on a sensing signal of the sensing unit, and the position By adding a control signal output means for outputting a control signal to the polarization state conversion element based on the information of the judgment means, the position of the observer is changed by automatically judging the position of the observer and changing the polarization state of the projected light. It is possible to obtain a viewing angle characteristic corresponding to. In other words, the viewing angle characteristics automatically change according to the position of the observer, and the limited image light can be effectively distributed in the direction of the observer, so that the observer can obtain a good image at an arbitrary position. There is an effect.

  Further, in the rear projection type display device of the present invention, the projection light from the projection device incident on the transmissive screen is made non-polarized, so that the color distribution due to the polarization dependency of the light distribution characteristic of the light distribution control element or the stripe pattern High-quality images with no image can be obtained.

  In this case, since a material having optical anisotropy may be used as the transparent base material of the light distribution control element, the selection range of the material is widened, and a transmission screen using a cheaper and higher strength material. Can be realized at low cost.

  Further, in the liquid crystal display device of the present invention, the light distribution control element according to the present invention is arranged on the surface side thereof, and light that emits illumination light substantially parallel to the backlight device is used. Only the light distribution control element can diffuse isotropically, so that there is no color tone change or gradation reversal in a wide viewing angle range, and a liquid crystal display device with a high contrast ratio can be obtained.

  Further, in the liquid crystal display device of the present invention, the light incident on the light distribution control element is linearly polarized light having a vibration direction in the horizontal direction with respect to the display surface, so that the viewing angle in the horizontal direction is wider than the vertical direction on the display surface. Thus, the limited light can be effectively distributed to the observer.

  Further, in the liquid crystal display device of the present invention, the polarization state of the light incident on the light distribution control element can be arbitrarily changed by the phase difference plate arranged between the analyzer and the light distribution control element, so the phase difference plate is changed. Only by using the polarization dependence of the light distribution characteristic of the light distribution control element, a predetermined viewing angle can be obtained.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing an example of a light distribution control element of the present invention, and FIG. 2 is a schematic perspective view thereof.

  This light distribution control element is composed of a transparent substrate 101, a hot-melt adhesive layer 104 formed on the surface thereof, and a plurality of microspherical transparent beads 105 fixed to the adhesive layer 104.

  The transparent substrate 101 itself may be a plate-like substrate having rigidity or a film-like substrate, but is optically substantially isotropic, or a plate surface or a film surface. It is important to use a uniaxially anisotropic transparent body having an optical axis in a direction parallel to the.

  Specifically, a glass plate, an optically isotropic transparent plate such as an acrylic resin plate formed by injection molding, or a polycarbonate resin formed by a casting method or an extrusion method, and uniaxially stretched as necessary. A uniaxial anisotropic transparent film having an optical axis substantially parallel to the film surface, such as a vinyl resin, a polyester resin, a cellulose resin, a polyvinyl alcohol resin, and a polyolefin resin, is used.

  The hot melt adhesive layer 104 has a structure in which a transparent layer 102 and a colored layer 103 are laminated in this order. The adhesive layer has a sufficient adhesive force to the transparent substrate 101 and the transparent beads 105. For this, a hot melt adhesive made of acrylic resin, polyester resin, polyamide resin, polyurethane resin or the like can be used. In addition, the colored layer 103 is formed by dispersing a pigment such as carbon black based on these adhesives, or colored by dyeing with a dye.

  As the transparent beads 105, spherical beads made of glass or optically isotropic and transparent resin are used, and the higher the refractive index, the larger the refraction angle of the light incident on the transparent beads. The light emission angle (viewing angle) becomes wider. However, the brightness of the front surface is reduced accordingly, and reflection on the surface and reflection at the interface between the transparent substrate 101 and air increase, and the total light transmittance decreases.

  Further, in order to transmit light efficiently through the opening on the light exit surface side of the transparent bead 105, that is, the contact portion between the transparent bead 105 and the transparent adhesive layer 102, the light exit surface side of the light incident on the transparent bead 105 is used. It is advantageous to reduce the convergence area at. In this case, if the medium on the light incident side of the transparent beads is air, the convergence area on the light exit surface can be made sufficiently small by setting the refractive index to about 1.6 to 2.1. Further, by setting the refractive index to 1.9 to 2.1, it is possible to collect light with smaller aberration.

  The refractive index of the transparent bead 105 is selected so as to meet the characteristics required for the light distribution control element, that is, the specifications of the viewing angle and the brightness (gain) based on these conditions. In addition, transparent beads having different refractive indexes can be mixed and used as necessary.

  When the light distribution control element 100 is used as a screen or a viewing angle expansion unit of a display device, the diameter of the transparent beads 105 directly affects the resolution of the displayed image. That is, the image displayed on the light distribution control element cannot be resolved below the diameter of the transparent beads 105. Therefore, it is necessary to make the diameter of the transparent beads smaller than the pixels of the image to be displayed on the light distribution control element.

  To obtain high resolution, the smaller the diameter of the transparent bead 105, the better. However, as the diameter of the transparent bead 105 approaches the wavelength region of light, the factor of scattering of transmitted light increases and the brightness and transmittance at the front surface decrease. Self and its lower limit are defined.

  The diameter of the transparent bead 105 is ½ or less of the pixel pitch of the display image, and is practically desirably about 20 to 100 μm. Further, since the transparent beads 105 are arranged uniformly and at the maximum density on the surface of the transparent substrate 101, it is desirable that the variation in the particle diameter is as small as possible. Actually, the function as the light distribution control element is satisfied if the variation in particle diameter is within 10%.

  Moreover, since the transparent bead 105 has a bubble reduction factor when air bubbles are present inside, it is desirable that the transparent beads 105 have no air bubbles.

  Next, an example of a method for producing the light distribution control element 100 of the present invention will be described with reference to FIG.

  Step (a): A hot-melt transparent adhesive dissolved in a heat-melted state on a transparent substrate 101 or dissolved in a solvent or colloidally dispersed in a solution, for example, spin coating, knife coating, roll coating, spray coating The transparent adhesive layer 102 is formed by applying by blade coating.

  Step (b): 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. At this time, in order to prevent the colored adhesive layer 103 and the transparent adhesive layer 102 from mixing, the colored adhesive layer 103 is formed by forced cooling or natural cooling when the transparent adhesive layer 102 is in a high-temperature molten state. Reduce the temperature. Further, if the transparent adhesive layer 102 is in a molten state in a solvent or in a colloidal state in a solution, the solvent may be evaporated and solidified or semi-solidified by a dryer.

  Step (c): At least one transparent bead 105 is dispersed and arranged on the colored adhesive layer 103 so as to have a maximum packing density. At this time, since the colored adhesive layer 103 does not have adhesiveness in a solidified or semi-solidified state, the transparent beads 105 can be dispersed and arranged at the maximum packing density relatively easily.

  Next, the above is heated by heating means such as a thermostatic bath, an infrared heater, etc., the hot melt adhesive layer 104 is softened and melted, and the transparent bead 105 is directed toward the transparent substrate 101 by its own weight or by pressurizing means. A predetermined amount is buried in the layer 104.

  Step (d): With the transparent beads 105 buried, the temperature of the hot melt adhesive layer 104 is lowered to room temperature and solidified to fix the transparent beads.

  Note that it is desirable that the buried depth of the transparent bead 105 in the hot melt adhesive layer 104 is 50 to 80% of the bead diameter exposed. When the exposure amount is smaller than this, the amount of incident light on the transparent beads 105 is reduced due to absorption by the colored adhesive layer, and the transmittance is reduced. On the other hand, if the exposure amount is larger than this, the bead adherence becomes insufficient.

  As described above, in the light distribution control element of the present invention, only one transparent bead 105 is dispersedly arranged at almost the maximum packing density, and more than half of the diameter is exposed from the hot melt adhesive layer 104 to the light incident side. A fixed one can be obtained.

  Next, the optical action of the light distribution control element of the present invention will be described with reference to FIG. In the light distribution control element 100, as described above, only one transparent bead 105 is dispersed and arranged at the maximum incident density on the light incident surface side, and more than half of the bead diameter is incident from the hot melt adhesive layer 104. Exposed and fixed to the side.

  Therefore, a part of the parallel incident 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 incident light 106 is incident on the transparent beads 105. To do. The incident light is converged by the refraction action of the transparent bead 105, passes through the opening formed in the contact portion between the transparent bead 105 and the transparent adhesive layer 102, and is emitted while being transmitted and diverged through the transparent base material 101. . That is, the incident light on the transparent beads is converged by the lens effect of the transparent beads and isotropically diverges, so that a light distribution control element having an isotropic and wide viewing angle can be obtained.

  Further, the unnecessary light 107 incident from the outside is absorbed by the colored adhesive layer 102 and the unnecessary light is not observed as stray light. Therefore, the effect of reducing stray light due to unnecessary external light is high even in a bright environment, and it is possible to obtain a light distribution control element having an isotropic viewing angle characteristic that is bright even when viewed by an observer.

[Removal of striped pattern when polarized light is incident]
Next, in order to clarify the effect peculiar to the light distribution control element of the present invention, the generation of a striped pattern that appears when observed from an oblique direction at the time of polarized light incidence, which was a conventional problem, will be described.

  FIG. 4 shows a light emission characteristic at the time of polarized light incidence of a conventional light distribution control element (consideration is not given to the problem according to the present invention) by an isoluminance diagram.

This isoluminance diagram is obtained by connecting and displaying the points where the maximum luminance is 100% in the coordinate system constituted by the emission angle and the azimuth angle shown in FIG.
In FIG. 4, the center portion indicates the emission angle 0 ° (front), and the dotted concentric circles indicate the emission angles (10 ° intervals). Further, the azimuth angle is displayed so as to increase counterclockwise with 0 ° in the downward direction of the drawing.

  As shown in FIG. 4, in the conventional light distribution control element, when polarized light is incident, luminance variations in a substantially concentric shape centering on two points near an emission angle of 40 ° appear. This can be visually recognized as a striped pattern when observed from an oblique direction.

  In the conventional light distribution control element used for this measurement, a flat polyethylene terephthalate (PET) film having a thickness of 120 μm was used as the transparent substrate 101. A transparent adhesive layer 5 μm made of a polyester hot melt adhesive is formed on the surface, and a colored adhesive layer 4.5 μm in which 10 parts by weight of carbon black is blended with the polyester hot melt adhesive is formed on the transparent adhesive layer. A spherical glass transparent bead having a ratio of 1.935 (wavelength: 589.3 nm) and a diameter of 50 μm is densely dispersed and buried and fixed in the above-mentioned adhesive layer.

  The thickness of the adhesive layer after fixing the transparent beads was about 21 μm, including the transparent layer and the colored layer, and about 58% of the diameter of the transparent beads was exposed from the adhesive layer.

  Here, in the light distribution control element, a biaxially stretched PET film was used as the transparent substrate 101. This is because the biaxially stretched film has significantly improved physical properties such as increased tensile strength and impact strength as compared with the unstretched film, and improved transparency and operating temperature range. Also, PET film has good adhesion to polyester hot melt adhesive with good adhesion to glass transparent beads, and also has good solvent resistance to the above hot melt adhesive (solvent: toluene). is there.

  For the above reasons, a biaxially stretched PET film was used as the transparent substrate. In general, however, the biaxially stretched film has three main refractive indices (direction perpendicular to the film film surface: Z-axis direction, parallel to the film surface and orthogonal to each other. Biaxially anisotropic materials with different directions (X-axis and Y-axis directions).

  Biaxial anisotropy is a substance in which when the refractive index ellipsoid is considered as shown in FIG. 6, the shape of the cut surface is circular and the direction in which refractive index anisotropy does not occur is determined in two directions. The direction of this light is called the optical axis, and since there is no refractive index anisotropy in the optical axis, there is no phase difference in polarized light traveling in parallel therewith. For example, in the case of the PET film used in the above-mentioned conventional example, the three main refractive indexes are nx = 1.678, ny = 1.645, nz = 1.497, and the optical axis is Z-axis as shown in FIG. There are two in the ZX plane at an angle of 23.3 °.

  The light that has traveled along the optical axis in the PET film is refracted at the interface with the air and is emitted at an exit angle of 41.6 °. Therefore, the approximate center position of the luminance fluctuation in the vicinity of the exit angle of 40 ° shown in FIG. It corresponds to this optical axis.

  Here, consider a case where light of a specific polarization state (linearly polarized light or elliptically polarized light) is incident on the light distribution control element. In this case, most of the light incident on the light distribution control element is converged by the transparent beads, and then diverges and travels through the PET film at various angles. At this time, since the phase difference does not occur in the light traveling along the optical axis in the PET film, the polarization state does not change.

  However, since the light traveling at an angle shifted from the optical axis has a phase difference corresponding to the shift in the angle, the polarization state, that is, the p-polarized component parallel to the light incident surface at the PET film light exit side interface, The ratio of the vertical s-polarized component changes. That is, in light traveling in a direction different from the optical axis direction, light having a large amount of p-polarized light component and light having a large amount of s-polarized light component appear alternately corresponding to the magnitude of deviation from the optical axis.

  Here, in general, the refraction of the dielectric surface causes a difference in energy transmittance between p-polarized light and s-polarized light. FIG. 8 illustrates the difference in energy transmittance between p-polarized light and s-polarized light, and is a graph showing the relationship between the light incident angle and the energy transmittance when light travels from the PET film into the air.

  As shown in FIG. 8, a difference in transmittance of 30% or more is maximum between p-polarized light and s-polarized light. For this reason, there is a difference in the amount of transmitted light between light with a large amount of p-polarized light component and light with a large amount of s-polarized light component, and brightness brightness is formed, which is visually recognized as a striped pattern.

  In particular, in a light distribution control element using a microlens represented by transparent beads, the light incident on the microlens converges and travels at various angles while diverging. Due to the difference in phase difference based on the difference in the traveling angle of light, the luminance unevenness (change) of the emitted light is very likely to occur.

  In the light distribution control element of the present invention, the transparent substrate 101 is optically isotropic or uniaxially anisotropic having an optical axis parallel to the film surface. Therefore, the polarized light incident on the light distribution control element is converged by the transparent beads and proceeds at various angles while diverging, but the transparent substrate is optically isotropic. There is no difference in phase difference, and the polarization state, that is, the ratio of the p-polarized component and the s-polarized component hardly changes depending on the emission angle, so that no stripe pattern is generated.

  In addition, when the polarized light incident on the light distribution control element is linearly polarized light, if the transparent substrate is a uniaxially anisotropic material having an optical axis in the plane, the vibration direction of the electric vector of the incident linearly polarized light is transparent. By making the material parallel or perpendicular to the slow axis of the material, the difference in phase difference due to the traveling angle of polarized light passing through the transparent substrate can be reduced, and the occurrence of a striped pattern can be suppressed.

  Furthermore, even if the transparent substrate has optical anisotropy, if the difference in phase difference due to the traveling angle of light traveling through the transparent substrate is small and the change in polarization state is small, the change in luminance is visible. Not allowed.

  For example, if the maximum value of the difference in phase difference due to the difference in the traveling angle of light traveling inside the transparent substrate is ½ wavelength or less, the change in the polarization state due to the angle of the light passing through the transparent substrate is maximum. However, since the light with 100% p-polarized light component is only converted to light with 100% s-polarized light component, the change in luminance is hardly visible.

  More ideally, it is desirable to keep the maximum value of the difference in phase difference depending on the angle of light passing through the transparent substrate within a quarter wavelength. In this case, at most, for example, light with 100% p-polarized light component is only converted into light with 50% p-polarized light component and 50% s-polarized light component.

  Therefore, the optically isotropic transparent base material referred to here is a small difference in phase difference due to the difference in the traveling angle of light traveling in the transparent base material, and therefore the change in the polarization state is small, and the luminance is reduced. This means something that is isotropic to the extent that no change is observed.

  As described above, in the light distribution control element of the present invention, the transparent base material is optically substantially isotropic, or a uniaxial anisotropic transparent body having an optical axis in the plane is used. However, the image quality is not deteriorated due to the generation of the stripe pattern, and a wide viewing angle can be obtained.

  Further, since unnecessary light 107 incident on the light distribution control element 100 from the outside is absorbed by the colored adhesive layer 102, unnecessary light is not observed as stray light. Therefore, stray light due to unnecessary external light is reduced even in a bright environment.

  Since the energy transmittance of the dielectric surface is different between p-polarized light and s-polarized light as described above, the transmittance of the p-polarized component is high on the surface of the transparent bead 105 or the transparent substrate 101, and the light of the s-polarized component. Decreases the transmittance. As a result, anisotropy occurs in the light distribution characteristics of the emitted light depending on the polarization state of the incident light.

  For example, when linearly polarized light is incident on the light distribution control element, the viewing angle in the direction parallel to the vibration direction of the electric vector of the linearly polarized light is wider than the direction orthogonal thereto. If this characteristic is utilized, the viewing angle in the horizontal direction can be made larger than the viewing angle in the vertical direction by making the linearly polarized light whose oscillation direction of the electric vector is horizontal enter the light distribution control element.

  Contrary to the above, the vertical viewing angle can be made larger than the horizontal viewing angle by making the oscillation direction of the electric vector of the incident linearly polarized light vertical. Furthermore, if the light incident on the light distribution control element is circularly polarized light, an isotropic viewing angle can be obtained.

  That is, the light distribution control element of the present invention can arbitrarily control the viewing angle by controlling the polarization state of the light incident thereon.

  In the above description, the case where microspherical transparent beads are used as the microlens has been described. However, the shape of the micro condensing lens is not limited to a sphere, such as a hemisphere, a spheroid, a cylinder, a semi-cylinder, or an elliptic cylinder, as long as it has a condensing function. That is, the light distribution control element of the present invention is composed of a microlens having a condensing function and a transparent base material that supports the lens, and the transparent base material disposed on the light emitting side is optically substantially isotropic transparent body. This prevents the occurrence of different phase differences in the light traveling at different angles in the transparent base material, thereby eliminating the occurrence of striped patterns (brightness unevenness).

  Next, the light distribution control element of the present invention will be described based on specific examples.

[Example 1 of light distribution control element]
In this example, the light distribution control element shown in FIGS. 1 and 2 was manufactured as follows. First, a polyester-based hot-melt transparent adhesive (made by Toyobo) using toluene as a solvent is applied to one surface of a transparent substrate 101 made of a flat triacetylcellulose (TAC) film having a thickness of 80 μm. The transparent adhesive layer 102 was formed and solidified by coating with a knife coater so that the thickness was 4 μm, drying with a dryer, and then cooling.

  Next, a colored adhesive in which 10 parts by weight of carbon black is mixed with the polyester hot melt adhesive is formed and solidified in the same manner as the adhesive layer 102 so that the thickness after drying is 5.5 μm. Thus, a colored adhesive layer 103 was formed.

Next, a plurality of glass spherical transparent beads 105 having a refractive index of 1.935 (wavelength: 589.3 nm) and a diameter of 50 μm are dispersed on this so as to have a substantially maximum packing density, and pressure is applied using a pressure plate. While being pressurized to the transparent substrate 101 side at 4.5 kg / cm ^2, it is held at 120 ° C. for 20 minutes in a constant temperature bath. 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 was about 21 μm, and 58% of the diameter of the transparent beads 105 was exposed.

  The TAC film used for the transparent substrate 101 was an optically isotropic transparent film with (ne-no) = 0.0001 and (nz-no) = 0.0007.

  When the non-polarized light is incident on the above light distribution control element, it is isotropic and has a wide viewing angle of about ± 60 ° in both the horizontal direction and the vertical direction (here, the luminance is ½ of the front luminance). Angle) was obtained.

  Further, when linearly polarized light was incident, luminance unevenness causing a stripe pattern was not observed, and the observer was bright from any angle and a wide viewing angle characteristic was obtained.

  FIG. 9 is an isoluminance diagram showing the light emission characteristic of the light distribution control element of this embodiment when linearly polarized light is incident. FIG. 10 shows the horizontal direction and the horizontal direction of the light distribution control element of this embodiment when linearly polarized light is incident. The light emission (light distribution) characteristic in the vertical direction is shown.

  As shown in FIGS. 9 and 10, the light distribution control element of this embodiment has polarization dependency in the emission (light distribution) characteristics, and is parallel to the vibration direction of the electric vector of the incident linearly polarized light (in the figure, horizontal). The viewing angle (± 75 °) in the direction is wider than the viewing angle (± 45 °) in the direction orthogonal thereto. This is due to the following reason.

  In this light distribution control element, most of the polarized light incident on the transparent beads 105 is condensed while maintaining the polarization state substantially, diffuses, travels through the transparent substrate 101 at various angles, and exits. At this time, since the transparent bead 105 is a sphere, the angle of refraction is isotropic regardless of the polarization. However, since the energy transmittance is different between p-polarized light and s-polarized light on the surface of the transparent bead 105 or the light emitting side of the transparent substrate 101, the transmission of the p-polarized component to the surface of the transparent bead 105 or the transparent substrate 101. The rate is high, and the transmittance of the s-polarized component is low, resulting in polarization dependence in the light distribution characteristics.

  Therefore, if circularly polarized light is incident on the light distribution control element, an isotropic viewing angle can be obtained as in the case where non-polarized light is incident. That is, if a rotationally symmetric microlens such as a spherical transparent bead is used as the microlens as in this light distribution control element, the light distribution characteristics can be changed relatively easily depending on the polarization state of incident light.

  Further, except that transparent beads having a refractive index of 1.7 were used, a light distribution control element was manufactured in the same configuration as in the above example, and the characteristics were examined by introducing non-polarized light. The viewing angle was ± 37 ° 1.8 times that of the example. That is, in this light distribution control element, the gain and the viewing angle can be changed by changing the refractive index of the transparent beads. That is, a light distribution control element having desired characteristics can be realized by appropriately selecting the refractive index of the transparent beads.

[Example 2 of light distribution control element]
In this example, the light distribution control element shown in FIGS. 1 and 2 was produced as follows. After drying a polyester-based hot-melt transparent adhesive dispersed in an aqueous medium on one surface of a transparent substrate 101 made of a flat polycarbonate (PC) film having a thickness of 100 μm formed by a casting method (solution casting method) The transparent adhesive layer 102 was formed and solidified by coating, heating and drying with a knife coater such that the thickness of the transparent adhesive layer was 4 μm, followed by cooling.

  Next, a colored adhesive layer 103 in which 10 parts by weight of carbon black is blended with a polyester hot melt adhesive is formed and solidified in the same manner as described above so that the thickness after drying becomes 5.5 μm.

  Next, glass spherical transparent beads 105 having a refractive index of 1.935 (wavelength: 589.3 nm) and a diameter of 50 μm were buried and fixed in the hot melt adhesive layer 104 in the same manner as in Example 1. . The thickness of the hot-melt adhesive layer 104 after fixing was about 21 μm, and the transparent beads 105 had 58% of their diameter exposed. The PC film used for the transparent substrate 101 is an optically isotropic transparent film with (ne-no) ≦ 0.0001 or less. As a result of evaluating circularly polarized light incident on this light distribution control element, there was no luminance unevenness causing a stripe pattern, and an isotropic and wide viewing angle of about ± 60 ° was obtained. In addition, when linearly polarized light is incident, there is no luminance unevenness that causes a stripe pattern, and the viewing angle in the direction parallel to the vibration direction of the electric vector of the incident linearly polarized light is wider than the viewing angle in the direction orthogonal thereto. Characteristics were obtained.

[Example 3 of light distribution control element]
In this example, the light distribution control element shown in FIGS. 1 and 2 was produced as follows. Polyester hot-melt transparent adhesive dispersed in an aqueous medium is dried on one surface of a transparent substrate 101 made of a flat PC film with a thickness of 100 μm, uniaxially stretched, formed by an extrusion method (melt extrusion method) After coating and drying with a knife coater so that the subsequent thickness was 4 μm, the transparent adhesive layer 102 was formed and solidified by cooling.

  Next, the colored adhesive layer 103 is formed and solidified in the same manner as in Examples 1 and 2, and the transparent beads 105 are dispersed and disposed thereon, and then held at 120 ° C. for 30 minutes while being pressurized. Buried and fixed in The thickness of the hot-melt adhesive layer 104 after fixing was about 21 μm, and the transparent beads 105 had 58% of their diameter exposed.

  The PC film used for the transparent substrate 101 was a uniaxial anisotropic transparent film having an optical axis in a direction parallel to the film surface of (ne-no) = 0.0014.

  When linearly polarized light whose vibration direction of the electric vector is parallel or perpendicular to the slow axis of the transparent substrate 101 is incident on this light distribution control element, there is no luminance unevenness causing a striped pattern, and the incident linearly polarized light Outgoing characteristics were obtained in which the viewing angle in the direction parallel to the vector vibration direction was wider than the viewing angle in the direction perpendicular to the viewing angle.

  Further, in this light distribution control element, the transparent base material was improved in physical properties such as tensile strength and initial elastic modulus by uniaxial stretching, and a sheet-like light distribution control element with less curling could be obtained.

[Example 4 of light distribution control element]
In this example, the light distribution control element shown in FIGS. 1 and 2 was produced as follows. After drying an acrylic hot-melt transparent adhesive on one surface of a flat transparent substrate 101 made of an alicyclic acrylic resin (trade name Optretz: manufactured by Hitachi Chemical Co., Ltd.) having a thickness of 2 mm formed by injection molding The film was applied by a spin coater so that the thickness of the film became 4 μm, dried and then cooled to form and solidify the transparent adhesive layer 102.

  Next, a colored adhesive layer 103 in which 10 parts by weight of carbon black is blended with an acrylic hot melt adhesive is formed in the same manner as the transparent adhesive layer 102 so that the thickness after drying is 5.5 μm. Solidified.

  A spherical transparent bead 105 made of glass having a refractive index of 1.935 (wavelength: 589.3 nm) and a diameter of 50 μm is dispersed on this, and held at 120 ° C. for 20 minutes while being pressurized in the same manner as in the above example. It was buried and fixed in the hot melt adhesive layer 104. The thickness of the hot-melt adhesive layer 104 after fixing was about 21 μm, and the transparent beads 105 had 58% of their diameter exposed.

  In addition, the alicyclic acrylic resin used for the transparent substrate 101 was optically isotropic with (ne-no) = 0.0007.

  When this light distribution control element was evaluated by making circularly polarized light incident thereon, there was no luminance unevenness causing a striped pattern, and an isotropic and wide viewing angle of about ± 50 ° was obtained. In addition, when linearly polarized light is incident, there is no luminance unevenness causing stripe patterns, and the viewing angle in the direction parallel to the vibration direction of the electric vector of the incident linearly polarized light is wider than the viewing angle in the direction orthogonal thereto. Outgoing characteristics were obtained.

  The light distribution control element of this embodiment can be used as a screen of a rear projection display device without a reinforcing member or the like because the transparent substrate 101 itself has rigidity.

  In the above embodiment, spherical transparent beads are used as the microlenses, but microlenses having other shapes may be used. FIG. 34 is a schematic perspective view showing an example using microlenses having other shapes. This is a cylindrical transparent rod 3401 that is the same as the above embodiment except for this.

  This light distribution control element has no convergence effect in the major axis direction of the minute transparent rod 3401 with respect to the incident light, but has a convergence effect only in the direction orthogonal to the major axis direction, and only in this direction. A wide viewing angle can be obtained. Also in this case, the use of a transparent substrate having a small optical anisotropy can avoid the generation of a stripe pattern when polarized light is incident.

  In addition, when the light incident on the light distribution control element is linearly polarized light, the polarized light is p-polarized with respect to the incident surface of the microtransparent rod by making the oscillation direction of the polarized light parallel to the major axis direction of the microtransparent rod. Therefore, the light distribution control element can be used with high transmittance.

  By the way, in each said Example, although the microlens was comprised with the micro object shape | molded previously, such as a transparent bead and a rod, the light distribution control element of this invention is not restricted to this. That is, it is possible to form a large number of microlenses in a two-dimensional array directly on a transparent substrate. FIG. 35 is a schematic perspective view showing an example of such a light distribution control element. This light distribution control element is formed, for example, by forming microlenses 3502 into a two-dimensional array on a substantially optically isotropic transparent substrate 3501 such as glass, unstretched PC film, TAC film, or injection-molded acrylic resin plate. Further, a black light absorption layer (black matrix) 3503 having an opening at the light converging portion of the micro lens 3502 is formed.

  The light absorption layer 3503 can be formed by a known technique such as a printing method, a vapor deposition method, or a photolithography method. Further, the microlens 3502 is a known technique, for example, a method in which a positive photoresist is subjected to pattern exposure and developed to obtain a cylindrical three-dimensional shape, and then a dome-shaped microlens is formed by surface tension during heating and melting, A transparent resin film that is cured by irradiation with a light beam or an electron beam can be formed on the transparent base material 3501, and can be formed by selectively irradiating it with a light beam or an electron beam to cure, and removing an uncured portion. .

  In any case, the transparent base material 3501 is made of an optically isotropic transparent body or a transparent body having uniaxial optical anisotropy, thereby solving the problem of generation of a stripe pattern when polarized light is incident. can do.

[Embodiment 1 of rear projection display device]
Next, a rear projection display device using the light distribution control element of the present invention will be described. FIG. 11 is a schematic cross-sectional view of a rear projection display device.

  In the projection display device of the present invention, as shown in FIG. 11, the projection light 704 from the projection device 701 is irradiated onto the transmission screen 703 via the mirror 702 and an image is displayed. As the mirror 702, an optically isotropic transparent glass deposited with a reflective metal such as silver or aluminum was used.

  As the projection device 701, a so-called liquid crystal projector can be used. FIG. 12 is a schematic cross-sectional view showing an example of a liquid crystal projector.

  The light source 801 is composed of a paraboloidal or ellipsoidal reflector and a white light source such as a xenon lamp, a metal halide lamp, or a halogen lamp. , The white light from which the ultraviolet rays and infrared rays have been removed is turned to the color separation dichroic mirror 802.

  White light incident on the color separation dichroic mirror 802 is separated into blue light (B) and other light, and the blue light (B) is reflected by the total reflection mirror 804 and reaches the liquid crystal display element 807.

  On the other hand, the green light (G) and the red light (R) reflected by the color separation dichroic mirror 802 are separated by the color separation dichroic mirror 803, and the green light (G) is sent to the liquid crystal display element 809 and the red light (R). Are reflected by total reflection mirrors 805 and 806 and reach the liquid crystal display element 808. As the liquid crystal display elements 807, 808, and 809, TN liquid crystal display elements can be used.

  FIG. 13 is a schematic cross-sectional view showing an example of a TN liquid crystal display element. This liquid crystal display element includes a transparent electrode 903 made of ITO (Indium Tin Oxide), a first transparent glass substrate 901 having a light distribution film 905 made of polyimide polymer, a light distribution film 906, and a transparent electrode forming pixels. 904, between a second transparent glass substrate 902 having a switching element such as a wiring or a thin film transistor (not shown) connected thereto, and two transparent glass substrates 901 and 902 bonded via a sealant 908, And a liquid crystal layer 907 made of nematic liquid crystal with positive dielectric anisotropy.

  The direction of the major axis of the liquid crystal molecules of the liquid crystal layer 907 is determined by rubbing the light distribution films 905 and 906 formed on the two transparent glass substrates 901 and 902, and is continuously between the transparent glass substrates. The twisted state is 90 °.

  A polarizer 909 and an analyzer 910 are respectively disposed on the light incident surface and the light emitting surface of the liquid crystal display element so as to transmit linearly polarized light orthogonal to each other, and the liquid crystal molecules of the liquid crystal layer 907 in the transparent glass substrates 901 and 902 are disposed. The major axis orientation directions are configured to be both parallel or orthogonal to the linearly polarized light transmission axes of the polarizer 909 and the analyzer 910, respectively.

  A polarizer 909 and an analyzer 910 are obtained by applying a triacetyl cellulose (TAC) protective layer on both surfaces of a film obtained by absorbing iodine into stretched polyvinyl alcohol (PVA) to provide a polarizing function, respectively, and using transparent glass substrates. 901 and the transparent glass substrate 902 are bonded so as to be optically bonded by an acrylic adhesive.

  Here, the operation of the liquid crystal display element will be described. The linearly polarized light incident on the liquid crystal display element and transmitted through the polarizer 909 passes through the liquid crystal layer 907 and enters the analyzer 910. At this time, since the polarization state of the light transmitted through the liquid crystal layer 907 changes depending on the electric field applied to the liquid crystal layer 907, a voltage corresponding to image information is applied to the transparent electrode 905 and the transparent electrode 904, and the liquid crystal layer 907 is applied. By applying an electric field, the amount of light transmitted through the analyzer 910 can be controlled to form an optical image.

  Accordingly, each color light incident on the liquid crystal display elements 807, 808, and 809 in FIG. 12 is spatially modulated and emitted according to the respective image information. Each color light modulated by each liquid crystal display element passes through polarization state alignment means 812, 813, and 814, which will be described in detail later, enters and is combined with a color combining cross dichroic prism 811, and then passes through a projection lens 810. The light is projected on the transmission screen 703.

  FIG. 14 is a schematic cross-sectional view of a transmission screen 703 of the rear projection display device of the present invention.

  The transmission screen 703 includes a Fresnel lens sheet 801 and the light distribution control element 100 of the present invention. The Fresnel lens 801 is an optical component that operates in the same manner as a convex lens, and collimates the diffuse projection light emitted from the projection device 701 and converts the incident angle of light incident on the light distribution control element 100 to 0 degrees or the vicinity thereof. Work.

  Here, the light distribution control element 100 of the present invention has such a property that the transmittance decreases as the incident angle increases. FIG. 15 is a schematic diagram for explaining a decrease in transmittance based on an increase in incident angle.

  When the incident angle θ of light increases, the incident light 106 is converged by the transparent beads 105 and is emitted from the transparent base material 101 while diverging. At this time, the incident angle at the interface between the transparent base material 101 and air is large. Therefore, the reflection increases and the transmittance decreases significantly. Further, when the incident angle θ increases, the light that has entered and converged on the transparent bead 101 cannot pass through the opening of the light distribution control element 100, that is, the contact portion between the transparent bead 105 and the transparent adhesive layer 102. The transmittance is reduced by being absorbed by the adhesive layer 103.

  FIG. 16 is a graph showing an example of the relationship between the incident angle of light and the transmittance of the light distribution control element 100. The horizontal axis represents the light incident angle θ, and the vertical axis represents the relative transmittance with the transmittance at the incident angle θ = 0 ° being 1.

  When the incident angle θ exceeds 10 °, the transmittance rapidly decreases. Therefore, the spread of light incident on the light distribution control element 100 is preferably as small as possible, and practically, it is desirable that the half-value angle is within ± 10 °.

  Therefore, this light distribution control element is used for a transmission screen of a rear projection display device using a conventional three-tube projection device using three CRT projection tubes corresponding to, for example, the three primary colors R, G, and B. In addition, since the incident angles of the respective color lights incident on the light distribution control element are different, there is a problem that the transmittance of each color light is different, white balance is deteriorated, and a strong color shift appears.

  For this reason, the rear projection display device of the present invention is characterized in that a single-tube projection device is used as the projection device to be used. In the single tube system, the incident angles of the light beams of the respective colors to the transmissive screen coincide with each other. Therefore, the above-described white balance is not lowered and the color shift is not caused.

  Further, a Fresnel lens 801 is arranged on the light incident side of the light distribution control element 100 constituting the transmissive screen 703 so that the divergent projection light 704 from the projection device 701 is collimated and incident light to the light distribution control element 100 is reflected. By converting the incident angle to substantially 0 degrees, a decrease in transmittance in the light distribution control element 100 is suppressed, and the luminance of the display image can be improved.

  Here, the TN liquid crystal display element used as the two-dimensional optical switch element of the projection apparatus 701 generally has a linearly polarized light transmission axis of the polarizer 909 and the analyzer 910 in order to ensure the horizontal symmetry of the contrast ratio. The liquid crystal display element is disposed so as to form an angle of 45 ° or 135 ° with respect to the horizontal direction of the display surface of the liquid crystal display element. In this case, when a liquid crystal display element having the same configuration is used as the liquid crystal display elements 807, 808, and 809, the image light transmitted through the liquid crystal display element and the image light reflected once by the color synthesis cross dichroic prism 811 are once. The vibration direction of the electric vector of linearly polarized light (hereinafter referred to as the vibration direction of linearly polarized light) is different from the image light that is not reflected.

  That is, since the red light (R) and the blue light (B) that have passed through the liquid crystal display elements 807 and 808 are each reflected once by the color synthesis cross dichroic prism 811, the vibration direction of the linearly polarized light is the same, but the liquid crystal display element 809. Since green light (G) that has passed through has never been reflected by the color synthesis cross dichroic prism 811, the vibration direction of the linearly polarized light is orthogonal to the vibration direction of the linearly polarized light of the other color light.

  As described above, the emission characteristics of the light distribution control element 100 of the present invention change depending on the polarization state of incident light. Therefore, when the light distribution control element of the present invention is used as a transmission screen of a conventional rear projection display device, the image is green when observed from a certain direction, and is observed from an oblique direction opposite to this. Then, the image has a magenta color.

  In order to correct this, the rear projection display device 701 of the present invention is characterized in that polarization state alignment means 812, 813, 814 are arranged on the light exit side of the liquid crystal display elements 807, 808, 809.

  The polarization state aligning means 812, 813, and 814 have a function of matching the polarization state of each color light before the color light emitted from the liquid crystal display element is projected onto the transmission screen 703.

  FIG. 17 is a schematic cross-sectional view showing an example of the polarization state aligning means. The polarization alignment means includes a transparent substrate 1001 on which a polyimide alignment film 1003 is formed, a transparent substrate 1002 on which a polyimide alignment film 1004 is also formed, and a nematic liquid crystal sealed between these two transparent substrates. And a liquid crystal layer 1006 made of A gap is secured between the two transparent substrates 1001 and 1002 by a spacer (not shown), and the two transparent substrates are bonded by sealing the periphery with a sealant 1005 to seal the liquid crystal.

  FIG. 18 illustrates the operation of the polarization state aligning means. For easy understanding, the orientation directions of the liquid crystal molecule major axes in the vicinity of the transparent substrate of the liquid crystal display element and the polarization state aligning means are indicated by arrows 911 and 911, respectively. 912, 1007, and 1008.

  As illustrated in FIG. 18, the liquid crystal layer 1006 of the polarization alignment means has a liquid crystal molecular major axis twisted 45 ° between the two transparent substrates by the alignment films on the two transparent substrates 1001 and 1002. The liquid crystal alignment direction 1008 on the substrate 1001 side is horizontal with respect to the display surface of the liquid crystal display element.

  On the other hand, the liquid crystal alignment direction 1007 on the transparent substrate 1002 side on the liquid crystal display element side is parallel to the liquid crystal alignment direction 912 of the transparent substrate 910 on the light output side of the liquid crystal display element, and is in the horizontal direction of the display surface of the liquid crystal display element. It is inclined at 45 °.

  This polarization state aligning means is configured to satisfy the conditions of the wave guide for the main wavelength region of incident light. Wave guide conditions are described, for example, in a paper by C. H. Gooch and H. A. Tarry on pages 1575-1584 of J. Phys. D: Appl. Phys. Vol. 8 (1975).

That is, in order to rotate the light of wavelength λ by 45 ° by the wave guide, the layer thickness d of the liquid crystal layer 1006 of the polarization alignment means and the birefringence Δn at the wavelength λ are set so as to satisfy the equation (1). Good.
[Equation 1]
4d · Δn / λ = V (4m ² −1) (1)
Here, m is an arbitrary integer.

  Therefore, d and Δn of the polarization state alignment means 812, 813, 814 may be set so as to satisfy the expression (1) with respect to the principal wavelength of light incident thereon, and here, the polarization state alignment means 812, The main wavelengths of light incident on 813 and 814 are 450 nm, 650 nn, and 550 nm, respectively, and m = 4, so that d · Δn is 626 nm, 903 nm, and 765 nm, respectively.

  Since the conditions of the wave guide do not change between the extraordinary light mode and the ordinary light mode, the alignment direction of the liquid crystal of the polarization state aligning means is 90 with respect to the alignment direction exemplified in FIG. A rotated one may be used.

  With this configuration, when the linearly polarized light that has passed through the liquid crystal display elements 807, 808, and 809 passes through the polarization state aligning means 812, 813, and 814, the vibration direction of the electric vector rotates by 45 °. The polarization state of each color light becomes linearly polarized light having a vibration direction in the horizontal direction with respect to the display surface of the liquid crystal display element, and all of them coincide.

  Moreover, the following effects are acquired by making the vibration direction of the linearly polarized light of each color light into a horizontal direction with respect to a display surface like a present Example.

  In general, in a single-tube projection apparatus using a plurality of two-dimensional optical switch elements, a cross dichroic prism or a dichroic mirror is used to synthesize optical image light formed by the two-dimensional optical switch elements.

  The reflecting surface of the dichroic prism or dichroic mirror is formed of a dielectric multilayer film, and linearly polarized light incident obliquely thereto is p-polarized parallel to the incident surface or perpendicular to the incident surface. In the case of other than s-polarized light, the polarization state changes upon reflection, generally becomes elliptically polarized light, and the polarization state differs for each color light. However, as described above, if the direction of vibration of the linearly polarized light of each color light is incident in the horizontal direction with respect to the display surface, that is, the p-polarized light on the reflective surface of the color synthesis dichroic prism, the polarization state of each color light does not change. The optical image light can be projected onto the transmission screen while the polarization states of all the color lights are matched.

  That is, in the rear display device of the present invention, since the polarization states of the respective color lights projected from the projection device 701 are the same, coloring is caused by the polarization dependency of the light distribution characteristic of the light distribution control element 100 used as the transmission screen 703. Is eliminated and a high-quality image can be obtained.

  Further, since the projection light incident on the transmissive screen 701 is linearly polarized light having a vibration direction in the horizontal direction with respect to the display surface, the light distribution characteristic of the light distribution control element 100 is more than in the vertical direction due to the polarization dependence. The viewing angle in the horizontal direction can be widened. In general, a display device is required to have a wider viewing angle in the horizontal direction than in the vertical direction, so that it is very effective in efficiently distributing the limited light to the observer.

  The rear projection display device having the above configuration is used as the light distribution control element 100 of the transmissive screen 703, and the thickness of the light distribution control element 100 illustrated in [Example 1 of light distribution control element] When evaluated using a 2 mm flat and transparent optically isotropic acrylic plate, horizontal viewing angle ± 75 °, vertical viewing angle ± 45 °, wide viewing angle in both directions was gotten. Furthermore, when observed from an oblique direction, there was no occurrence of striped pattern or coloring.

Further, since unnecessary light incident on the transmission screen from the outside is absorbed by the colored adhesive layer 103 of the light distribution control element 100, it has a low luminance of 0.5 cd / m ² in a bright environment (vertical illuminance 300 lx). Realized black display.

  The polarization state aligning means of the rear projection type display device of the present invention may be any means as long as it has a function of matching the polarization state of each color light emitted from the liquid crystal display element. A polymer laminated film having a structure or a half-wave plate can be used.

  The polymer laminated film having a twisted structure used as the polarization state aligning means is realized by laminating four retardation films made of a PC film having a retardation d · Δn = 275 nm, for example. In the four retardation films, the slow axes from the side closer to the liquid crystal display element are 5.6 °, 16.9 °, 28 with respect to the liquid crystal alignment direction of the transparent substrate on the light emission side of the liquid crystal display element. It arrange | positions so that it may become 0.1 degree and 39.4 degree. In this case, the same effect as in the above embodiment can be obtained.

  In addition, when a half-wave plate is used as the polarization alignment means, the slow axis of the wave plate that functions as a half-wave plate with respect to the wavelength of light that has passed through each liquid crystal display element is detected on the liquid crystal display element. The same effect as in the above embodiment can be obtained by placing the photon at 22.5 ° with respect to the transmission axis of the photon.

  Furthermore, a half-wave plate is disposed as a polarization state aligning means only on the light exit side of a liquid crystal display element in which the direction of oscillation of the emitted linearly polarized light is different from that of other liquid crystal display elements, and the polarization state of other liquid crystal display elements Can be prevented to some extent from being colored when observed from an oblique direction.

  In the above-described embodiment, the case where the transmission axis of the linearly polarized light of the analyzer of the liquid crystal display device is inclined by 45 ° with respect to the plane direction of the display surface has been described. For example, the transmission axis of the analyzer is previously set to the display surface. By using a liquid crystal display element configured to be horizontal or vertical with respect to the liquid crystal display element, the function of the polarization state aligning means can be provided in the liquid crystal display element. In this case, since the polarization state of each color light emitted from the liquid crystal display element is the same after the color composition, the same as in the above embodiment, even if another optical element is not disposed on the light emission side of the liquid crystal display element. An effect can be obtained.

  However, in this case, since the symmetry of the contrast ratio in the horizontal direction is lost, it is preferable to use a projection optical system having a high F value so that the left-right asymmetry of the contrast ratio is not recognized.

  As described above, in the rear projection display device of the present invention, the transmissive screen 703 is configured by the light distribution control element 100 and the Fresnel lens 801f disposed on the light incident side. For this reason, the divergent projection light 704 from the projection device 701 is collimated by the Fresnel lens 801f when incident on the light distribution control element 100, and the incident angle is substantially converted to 0 degrees. A decrease in transmittance at 100 is suppressed, and a bright display image is obtained.

  Further, in the present invention, by using a single tube type projection device as the projection device, it is possible to suppress color shift and coloring caused by the optical characteristics of the light distribution control element 100 and obtain a high-quality image.

  Further, by matching the polarization state of the light emitted from the projection device for each color light, there is an effect that it is possible to eliminate coloring that occurs when observed from an oblique direction due to the polarization dependence of the light distribution characteristic of the light distribution control element 100. is there. Further, the light distribution control element 100 of the present invention used as the transmissive screen 703 has a wide viewing angle characteristic that is bright from any angle and has a high effect of reducing stray light due to external unnecessary light. In addition, there is an effect that it is possible to realize a rear projection display device that can obtain a high contrast ratio by realizing low luminance black display even in a bright environment.

  In the above-described rear projection display device, the case where a plurality of two-dimensional optical switch elements are used in the projection device has been described. However, a so-called single-plate projection device using only one two-dimensional optical switch element is used. Also good. In this case, since there is originally only one two-dimensional optical switch element, the polarization state of the optical image light is uniquely determined evenly. Therefore, the color distribution is colored by the polarization dependence of the light distribution characteristic of the light distribution control element 100 of the present invention. Will not occur.

[Embodiment 2 of rear projection display device]
Next, another rear projection type display device of the present invention will be described. The rear throw type display device described here includes a projection device 701, a mirror 702, and a transmission screen 703 as in the embodiment described with reference to FIG. 11, and the projection light 704 emitted from the projection device 701 provides the mirror 702. The image is displayed on the transmissive screen 703 via the screen, but the configuration of the projection device 701 is partially different.

  FIG. 19 is a schematic cross-sectional view of a projection apparatus according to the rear projection type display apparatus of the present embodiment. This projection apparatus is basically the same as the projection apparatus illustrated in FIG. 12, except that the projection apparatus 701 described here has a polarization state conversion element 815 disposed between the projection lens 801 and the cross dichroic prism 811. Is a feature.

  In this projection apparatus, as in the above embodiment, the white light emitted from the light source 801 is color-separated into blue light (B), green light (G), and red light (R) by the color separation dichroic mirrors 802 and 803, and the mirror. The light enters the liquid crystal display elements 807, 809, and 808 via 804, 805, and 806, respectively. Each light incident on the liquid crystal display element is spatially modulated in accordance with the image information of each color and emitted, and each color light is converted into linearly polarized light having the same vibration direction by the polarization state aligning means 812, 813, and 814. The light enters the dichroic prism 811.

  At this time, each color light incident on the color synthesis cross dichroic prism 811 is preferably p-polarized light or s-polarized light with respect to the mirror surface of the prism 811. This is because the mirror surface of the color synthesizing prism 811 is composed of a dielectric multilayer film, and linearly polarized light incident obliquely on the mirror surface is parallel to the incident surface unless special design and film formation are performed. If it is not polarized light or s-polarized light perpendicular to the incident surface, the polarization state changes upon reflection, generally becomes elliptical polarization, and the polarization state of each color light is different.

  Here, an example in which image light is incident on the prism 811 as p-polarized light with respect to the mirror surface of the color synthesis cross dichroic prism 811, that is, linearly polarized light having a vibration direction in the horizontal direction with respect to the display surface will be described.

  The image light that has entered the color synthesis dichroic prism 811 and is color synthesized is projected onto the transmission screen 703 via the polarization state conversion element 815 and the projection lens 810.

  The polarization state conversion element 815 changes the polarization state of the image light after color synthesis. For example, a liquid crystal element shown in FIG. 20 can be used. The polarization state conversion element 815 shown in FIG. 20 includes a first transparent glass substrate 1101 in which a transparent electrode 1103 made of ITO and an alignment film 1104 made of polyimide-based polymer are entirely laminated, and the transparent electrode 1105 and the alignment film. A gap is formed by sandwiching a spacer (not shown) between the second transparent glass substrate 1102 in which the film 1106 is entirely laminated and the two transparent glass substrates 1101 and 1102, and the periphery is sealed with a sealant 1108. In this way, the liquid crystal layer 1107 made of nematic liquid crystal with positive dielectric anisotropy is formed in the space formed.

  The major axis of liquid crystal molecules of the liquid crystal layer 1107 is 90 ° continuously between the two substrates by performing alignment treatment such as rubbing treatment on the alignment films 1104 and 1106 formed on the two transparent glass substrates 1101 and 1102, respectively. It is a twisted so-called TN liquid crystal element.

  Next, the operation of the polarization state conversion element 815 will be described with reference to the drawings. 21 and 22 are schematic diagrams for explaining the operation of the polarization state conversion element 815, and arrows indicated by reference numerals 1110 and 1111 indicate the alignment directions of the liquid crystals on the transparent glass substrates 1101 and 1102, respectively.

  The alignment direction 1111 of the liquid crystal on the light incident side transparent glass substrate 1102 is parallel (or perpendicular) to the vibration direction of the electric vector of the incident linearly polarized light, and the liquid crystal layer 1107 satisfies the conditions of the wave guide in the visible wavelength range. Is.

  Therefore, when an electric field is not applied to the liquid crystal layer 1107 of the polarization state conversion element 815, as illustrated in FIG. 21, the vibration direction of the electric vector of the optical image light incident on the polarization state conversion element 815 is rotated by 90 °. The linearly polarized light, that is, linearly polarized light having a vibration direction perpendicular to the display surface is projected onto the transmission screen 703 via the projection lens 810.

  The transmissive screen 703 used in the rear projection display device is composed of a light distribution control element using spherical transparent beads as microlenses and a Fresnel lens, as in the previous embodiment.

  In this case, as described above, if the projection light incident on the transmissive screen 703 is linearly polarized light having a vibration direction perpendicular to the display surface, the light distribution characteristics of the light distribution control element 100 depend on the polarization dependency. The viewing angle in the vertical direction is wider than in the horizontal direction.

  In addition, as illustrated in FIG. 22, by applying a voltage to the transparent electrode 1103 and the transparent electrode 1105 formed on two transparent glass substrates and applying an electric field to the liquid crystal layer 1107, the liquid crystal molecules have their molecular lengths. When the axis is made substantially perpendicular to the transparent glass substrate, the optical image light incident on the polarization state conversion element 815 passes through the polarization state almost unchanged. That is, the light is projected on the transmission screen 703 through the projection lens 810 with the linearly polarized light having the vibration direction in the horizontal direction with respect to the display surface. In this case, the viewing angle in the horizontal direction becomes wider than in the vertical direction due to the polarization dependence of the light distribution characteristics of the light distribution control element 100 constituting the transmissive screen 703.

  That is, in the conventional rear projection display device, the viewing angle characteristics could not be changed unless the transmissive screen was replaced. However, in the rear projection display device of the present invention, it is applied to the liquid crystal layer of the polarization state conversion element 815. There is a revolutionary effect that the viewing angle characteristic can be easily changed by a simple operation of controlling the electric field.

  In addition, as the polarization state conversion element 815 of the rear projection display device of the present invention, an ECB (Electrically Controlled Birefringence) liquid crystal element can be used in addition to the TN liquid crystal element. In this case, since the only difference from the TN liquid crystal element is the portion related to the liquid crystal layer such as the thickness of the liquid crystal layer and the alignment direction of the liquid crystal molecules, the description will be given with reference to the schematic cross-sectional view of the TN liquid crystal element illustrated in FIG.

  Similar to the polarization state conversion element 815 formed of the TN liquid crystal element, the polarization state conversion element 815 formed of the ECB liquid crystal element has a transparent electrode 1103 made of ITO and an alignment film 1104 made of polyimide polymer on the entire surface. A laminated first transparent glass substrate 1101, a second transparent glass substrate 1102 in which a transparent electrode 1105 and an alignment film 1106 are entirely laminated, and a spacer (not shown) between the two transparent glass substrates. A gap is formed by being sandwiched, and a liquid crystal layer 1107 made of nematic liquid crystal sealed in a space formed by connecting the periphery with a sealant 1108 is formed.

  The dielectric anisotropy of the nematic liquid crystal may be positive or negative, but the liquid crystal orientation is homogeneous in the case of nematic liquid crystal with positive dielectric anisotropy, and nematic with negative dielectric anisotropy. In the case of liquid crystals, the homeotropic alignment is used.

  At this time, in order to align the alignment direction of the liquid crystal when an electric field is applied to the liquid crystal layer 1107, in both cases, a pretilt angle of about 1 to 4 ° is provided, and the molecular major axis direction of the liquid crystal is 45 with respect to the display surface. Alignment treatment is performed so as to be in the direction of °.

  When the thickness of the liquid crystal layer 1107 is d and the refractive index anisotropy of the liquid crystal is Δn, d · Δn is set to be λ / 2 (λ is the center wavelength of the optical image light) or more.

  In the polarization state conversion element 815 configured as described above, incident optical image light is applied by applying a voltage to the transparent electrodes 1103 and 1105 formed on the two transparent glass substrates and applying an electric field to the liquid crystal layer 1107. On the other hand, the apparent d · Δn of the liquid crystal layer 1107 can be controlled in the range of 0 to λ / 2.

  Accordingly, when the apparent d · Δn of the liquid crystal layer 1107 is 0, the optical image light that has entered the polarization state conversion element 815 passes through the polarization state almost unchanged, and thus the horizontal direction with respect to the display surface. Then, the light is incident on the transmission screen 703 as linearly polarized light having the vibration direction of. In this case, the viewing angle in the horizontal direction becomes wider than in the vertical direction due to the polarization dependence of the light distribution characteristics of the light distribution control element 100 constituting the transmissive screen 703.

  In addition, when the apparent d · Δn of the liquid crystal layer is λ / 2, the image light incident on the polarization state conversion element 815 is linearly polarized light whose oscillation direction of the electric vector is rotated by 90 °, that is, with respect to the display surface. Then, the light enters the transmission screen 703 as linearly polarized light having a vertical vibration direction. In this case, the viewing angle in the vertical direction becomes wider than in the horizontal direction due to the polarization dependence of the light distribution characteristics of the light distribution control element 100.

  Furthermore, when the apparent d · Δn of the liquid crystal layer is λ / 4, the image light incident on the polarization state conversion element 815 enters the transmission screen 703 as substantially circularly polarized light. In this case, an isotropic viewing angle that is approximately the same in both the vertical and horizontal directions can be obtained.

  Here, the operation of the polarization state conversion element 815 composed of an ECB liquid crystal element will be specifically described with reference to FIGS.

  A nematic liquid crystal having a dielectric anisotropy Δε = −4.2 and a refractive index anisotropy Δn = 0.083 was used as the liquid crystal of the polarization state conversion element 815, and the thickness of the liquid crystal layer was set to 3.5 μm. The alignment films 1104 and 1105 were polyimide-based alignment films exhibiting vertical alignment, and were rubbed in a direction forming an angle of 45 ° with respect to the horizontal direction of the display surface to give a pretilt of about 2 ° to the liquid crystal molecules.

  Since the apparent dΔn of the liquid crystal layer 1107 of the polarization state conversion element 815 is almost 0 when no electric field is applied, the polarization state of the incident optical image light changes almost as shown in FIG. Then, the light passes through the projection lens 810 and is projected onto the transmission screen 703 in a linearly polarized state having a vibration direction horizontal to the display surface. In this case, the viewing angle in the horizontal direction becomes wider than in the vertical direction due to the polarization dependence of the light distribution characteristics of the light distribution control element 100 constituting the transmissive screen 703.

  On the other hand, as shown in FIG. 24, a voltage is applied to the transparent electrodes formed on the two transparent glass substrates, and an electric field is applied to the liquid crystal layer 1107 so that the molecular major axis of the liquid crystal molecules is relative to the transparent glass substrate. By tilting from the vertical direction to the horizontal direction so that the apparent dΔn of the liquid crystal layer 1107 becomes 225 nm, the vibration direction of the electric vector of the image light incident on the polarization state conversion element 815 is rotated by about 90 °, The light enters the transmissive screen 703 as linearly polarized light having a vibration direction perpendicular to the surface or elliptically polarized light having a major axis in a direction substantially perpendicular to the display surface. In this case, the viewing angle in the vertical direction is wider than the horizontal direction due to the polarization dependence of the light distribution characteristics of the light distribution control element 100 constituting the transmissive screen 703.

  In addition, a voltage is applied to the transparent electrodes formed on the two transparent glass substrates of the polarization state conversion element 815, and an electric field is applied to the liquid crystal layer 1107, whereby the molecular major axis of the liquid crystal molecules is relative to the transparent glass substrate. When the apparent dΔn of the liquid crystal layer is set to 137.5 nm by tilting from the vertical direction to the horizontal direction, the optical image light incident on the polarization state conversion element 815 becomes substantially circularly polarized light and enters the transmission screen 703. . In this case, an isotropic viewing angle of the same level in both the horizontal direction and the vertical direction can be obtained due to the characteristics of the light distribution control element 100 constituting the transmissive screen 703.

  That is, in the conventional rear projection type display device, the viewing angle characteristic cannot be changed unless the transmissive screen is replaced. In this rear projection type display device, the TN liquid crystal element or ECB liquid crystal element is used. By controlling the electric field applied to the liquid crystal layer of the polarization state conversion element 815, the viewing angle in the horizontal direction is widened, the viewing angle in the vertical direction is widened, and the horizontal and vertical directions are the same isotropic The viewing angle characteristics can be easily changed so that a typical viewing angle can be obtained.

  In the above embodiment, the case where the viewing angle characteristic is made variable by using a liquid crystal element as the polarization state conversion element 815 has been described. However, in addition to this, for example, a retardation plate is disposed as the polarization state conversion element 815. Thus, a desired viewing angle characteristic may be obtained. For example, various modifications such as arranging a quarter wavelength plate as the polarization state conversion element 815 and obtaining an isotropic viewing angle by making the optical image light incident on the transmission screen 703 circularly polarized light. Can be considered.

[Embodiment 3 of rear projection display device]
Next, another rear projection type display device of the present invention will be described. FIG. 40 is a schematic configuration perspective view of the rear projection display device of the present embodiment.

  The rear projection type display apparatus of this embodiment receives the observation signal from the observer sensing section 4002 for sensing the presence or absence of the observer and the observer sensing section in the rear projection display apparatus of the second embodiment. Observer position determining means (not shown) for determining the position of the person in the horizontal and vertical directions, and control signal output means (not shown) for outputting a control signal to the polarization state conversion element arranged in the projection device 701 based on the information. Is added.

  The observer detection unit 4002 includes a plurality of observer detection sensors, and these observer detection sensors detect observers present in a plurality of divided areas. An infrared sensor is used as the observer detection sensor.

  41 and 42 exemplify the divided areas sensed by the observer sensing sensor. 41 shows a case where the vertical direction is divided into three regions I, II and III, and FIG. 42 shows a case where the horizontal direction is divided into three regions A, B and C. In this example, nine observer detection sensors for detecting the observer 4100 are necessary.

  The nine observer detection sensors provided in the observer detection unit 4002 detect the observer 4100 observed in front of the rear projection display device 4001, respectively, and the observer position determination means is vertical based on the respective detection signals. It is determined in which horizontal region (position) the observer 4100 exists. Based on the information of the observer position determination means, the control signal output means outputs a control signal to the polarization state conversion element of the projection device 701.

  Here, similarly to the second embodiment, the rear projection display apparatus according to the present embodiment changes the polarization state of the projection light 704 by the polarization state conversion element in the projection apparatus 701, thereby allowing the viewing angle of the transmission screen 703. The characteristics can be changed. That is, a bright image can be provided to the observer by sensing and judging the position of the observer, controlling the polarization state conversion element, and converting the polarization state of the projection light 704 to an appropriate state.

  Next, the effect of the rear projection display device will be described with reference to FIGS. 43 and 44. In general, in the rear projection type display device, in order to effectively distribute limited light in the viewer direction, the vertical viewing angle is set narrower than the horizontal viewing angle, as shown in FIG. In addition, the effective range in which an image with uniform brightness can be obtained over the entire surface of the screen 703 is narrow in the vertical direction. For this reason, the observer 4100 cannot obtain good image quality unless he / she observes at an appropriate height by sitting on a chair or observing at a certain distance.

  Therefore, as illustrated in FIG. 43, when the observer 4100 is able to view a good image when sitting on a chair, the image at the bottom of the screen 703 becomes dark when standing up and the good image cannot be viewed. There was a problem.

  However, in this rear projection display device, when the observer stands up, the observer 4102 that stands up is sensed by the observer sensing unit 4002, and the position of the observer is judged by the human body position judging means based on this sensed signal. The Further, the control signal output means controls the polarization state conversion element based on the position information of the observer, and converts the polarization state of the projection light into an appropriate state. A good image can be provided to the observer 4102 standing up with an enlarged viewing angle.

  More specifically, in the state illustrated in FIG. 43, the projection light projected on the screen 703 is linearly polarized light having a horizontal vibration direction with respect to the display surface of the screen 703, so that the horizontal direction is higher than the vertical direction. The viewing angle characteristics are wide.

  However, when the observer stands up, the polarization state conversion element is controlled based on the sensing signal of the observer sensing unit 4002, and the projection light has a vibration direction perpendicular to the display surface of the screen 703. By converting to linearly polarized light, as shown in FIG. 44, it is possible to widen the viewing angle in the vertical direction and provide a good image to the viewer 4102.

  As described above, the rear projection display device automatically changes the viewing angle characteristics according to the position of the observer, and can effectively distribute the limited image light in the direction of the observer. Good images can be obtained at the position.

[Embodiment 4 of rear projection display device]
Next, another rear projection type display device of the present invention will be described. The back throw type display device of this embodiment is the same as the embodiment described with reference to FIG. 11, but the configuration of the two-dimensional optical switch element used in the projection device 701 is different.

  The feature of the rear projection display device is that the two-dimensional optical switch element used in the projection device 701 displays in a non-polarized state without using polarized light for display. To avoid problems such as the generation of stripes due to the optical anisotropy of the transparent base material of the light distribution control element 100 and the change in chromaticity due to the polarization dependence of the light distribution characteristics of the light distribution control element. Features.

  Various types of two-dimensional optical switch elements that do not use polarized light for display are conceivable. First, a case where a polymer dispersion type liquid crystal element is used as a scattering type display element will be described.

  Polymer dispersed liquid crystals include nematic liquid crystals with positive dielectric anisotropy contained in microcapsules dispersed in a polymer, liquid crystal droplets dispersed in a polymer matrix, or a network in a continuous liquid crystal layer. There are polymers formed.

  FIG. 25 is a schematic cross-sectional view showing an example of a polymer dispersion type liquid crystal element. The polymer dispersed liquid crystal element 2500 includes a first transparent glass substrate 2501 having a transparent electrode 2503 made of ITO formed on the entire surface, a transparent electrode 2504 that forms a pixel, and a wiring, a thin film transistor, etc. (not shown) connected thereto. It comprises a second transparent glass substrate 2502 having a switching element and a polymer dispersed liquid crystal layer 2505 formed between two transparent glass substrates 2501 and 2502 connected via a sealant 2508.

  The polymer-dispersed liquid crystal layer 2505 is obtained by dispersing liquid crystal droplets 2506 having positive dielectric anisotropy in a polymer 2507 such as polyvinyl alcohol. The refractive index in the molecular minor axis direction of the liquid crystal and the refractive index of the polymer are substantially the same. ing.

  FIG. 26 shows the operation of the polymer dispersion type liquid crystal element. When no electric field is applied to the polymer dispersed liquid crystal layer 2505, the liquid crystals in the polymer dispersed liquid crystal layer 2505 are irregularly arranged under the influence of anchoring by the polymer side wall, the shape of the wall surface, surface energy, and the like. . Therefore, in the polymer dispersed liquid crystal layer 2505, fine particles having a refractive index distribution from the refractive index ne in the liquid crystal molecular major axis direction to the refractive index no in the liquid crystal minor axis direction are floating in the polymer matrix having the refractive index no. The incident light is refracted and scattered at the interface having a different refractive index.

  On the other hand, when a voltage is applied to the transparent electrodes on the transparent glass substrates 2501 and 2502 and an electric field is applied to the liquid crystal, the liquid crystal is aligned in the vertical direction with respect to the transparent glass substrate, and the liquid crystal is viewed from the light traveling direction. The refractive index of the liquid crystal is constant at no and coincides with the refractive index of the polymer matrix. Therefore, the incident light is transmitted without being scattered at the interface between the liquid crystal and the polymer.

  Thus, in the polymer dispersion type liquid crystal element, the degree of light scattering can be changed by applying / not applying an electric field to the polymer dispersion liquid crystal layer 2505. However, since the amount of light transmission does not change, in order to use this for display, an optical system that converts the degree of light scattering into light darkness is required. As is well known, a schlieren optical system is used for such a purpose.

  27 and 28 are schematic views for explaining the display operation of a polymer dispersion type liquid crystal element using a schlieren optical system. The substantially parallel light emitted from the light source 2801 is converged on the opening portion of the entrance-side stop 2803 by the action of the converging lens 2802, and the light passing through the opening portion of the entrance-side stop 2803 is converted into substantially parallel light again by the lens 2701. Incident on the liquid crystal element 2500. As shown in the drawing, when a sufficient electric field is applied to the polymer dispersed liquid crystal layer of the polymer dispersed liquid crystal element 2500, the light incident on the polymer dispersed liquid crystal element 2500 is transmitted as almost parallel light, and is converged by the converging lens 2702. The light is converged and passes through the opening of the exit side aperture 2817.

  On the other hand, as shown in FIG. 28, when an electric field is not applied to the polymer dispersed liquid crystal layer of the polymer dispersed liquid crystal element 2500, the light incident on the polymer dispersed liquid crystal element 2500 is scattered, and the opening of the exit side stop 2817 Can hardly pass. Accordingly, bright and dark display is possible by using the light passing through the exit side aperture 2817 for display.

  Next, a projection apparatus using a polymer dispersion type liquid crystal element as a two-dimensional optical switch element will be described.

  FIG. 29 is a schematic cross-sectional view showing an example of a projection apparatus using a polymer dispersion type liquid crystal element.

  The light source 2801 is composed of a rotating paraboloid reflector and a metal halide lamp in which a light emitting part is arranged at the focal point of the reflector, and most of the light emitted from the light emitting part is reflected by the reflector and becomes substantially parallel light. To do. The light emitted from the light source 2801 passes through a UV and IR cut filter (not shown) to become white light from which ultraviolet rays and infrared rays have been removed, and enters the opening of the incident side stop 2803 by the action of the incident side converging lens 2802. Converged.

  The white light that has passed through the incident-side stop 2803 is reflected by the red light reflecting dichroic mirror 2804, and the reflected red light is incident on the incident-side lens 2812 via the total reflection mirror 2807. Parallel light is incident on the polymer dispersion type liquid crystal element 2815 by the action of the lens.

  On the other hand, of the light transmitted through the red light reflecting dichroic mirror 2804, the green light component is reflected by the green light reflecting dichroic mirror 2805, enters the incident side lens 2811, and is converted into parallel light by the action, thereby polymer dispersed liquid crystal. Incident on element 2814.

  Further, the blue light transmitted through the green light reflecting dichroic mirror 2805 is incident on the incident side lens 2810, and is incident on the polymer dispersion type liquid crystal element 2813 as parallel light due to its action.

  Each color light incident on the polymer-dispersed liquid crystal elements 2813, 2814, and 2815 is emitted from the polymer-dispersed liquid crystal element with its scattering state controlled according to the respective image information. The red light that has passed through the polymer dispersion type liquid crystal element 2815 passes through the green light reflecting dichroic mirror 2808 and the blue light reflecting dichroic mirror 2809 and enters the projection lens 2819.

  Further, the green light that has passed through the polymer dispersion type liquid crystal element 2814 is reflected by the green light reflecting dichroic mirror 2808, is combined with the red light, passes through the blue light reflecting dichroic mirror 2809, and enters the projection lens 2819. The blue light that has passed through the polymer dispersion type liquid crystal element 2813 is reflected by the total reflection mirror 2806 and the blue-green light reflection dichroic mirror 2809, is combined with the red light and the green light, and enters the projection lens 2819.

  The projection lens 2819 includes a rear group lens 2816, a front group lens 2818, and an exit-side stop 2817 disposed therebetween.

  The rear lens group 2816 of the projection lens 2819 and the incident side lenses 2810, 2811, and 2812 have a conjugate relationship between the exit side stop 2817 of the projection lens and the incident side stop 2803. For this reason, among the light incident on the projection lens 2819, the light of the pixels not subjected to the scattering action in the polymer dispersion type liquid crystal elements 2813, 2814, and 2815 passes through the emission side stop 2817 and is brightly displayed.

  On the other hand, part or most of the pixel light subjected to the scattering action in the polymer dispersion type liquid crystal elements 2813, 2814, and 2815 cannot pass through the emission side stop 2817, and thus dark display is performed.

  Thus, the optical image light projected from the projection apparatus is in a substantially non-polarized state because polarized light is not used for display. That is, since the optical image light incident on the transmissive screen 703 is non-polarized, even if the transparent base material of the light distribution control element 100 constituting the screen has birefringence, the optical anisotropy of the transparent base material Problems such as the generation of a stripe pattern due to the property and the chromaticity change due to the polarization dependence of the light distribution characteristic of the light distribution control element are avoided. That is, since a transparent body having optical anisotropy may be used as the transparent base material of the light distribution control element, the material selection range is wide, and therefore, a cheaper and higher strength material can be used.

  According to the above, instead of an expensive film with low birefringence, for example, an expensive film with low strength such as a TAC film, an inexpensive and high strength film such as a biaxially stretched PET film is used as a member of a light distribution control element. The transmission screen of the rear projection display device can be realized at low cost.

  Here, the light distribution control element 100 used in the present embodiment will be described. The light distribution control element 100 has the same configuration as that illustrated in FIGS. 1 and 2. As the transparent substrate 101, a flat biaxially stretched PET film having a thickness of 120 μm was used. A biaxially stretched film has an increased tensile strength and impact strength as compared to an unstretched film, and the physical properties such as transparency and operating temperature range are remarkably improved.

  This light distribution control element 100 was produced by the method described below. A transparent adhesive layer made of a polyester-based hot melt adhesive is 5 μm on the surface of the transparent substrate 101, and a colored adhesive layer in which 10 parts by weight of carbon black is blended with a polyester-based hot melt adhesive is added to the surface of the transparent substrate 101. Form and once solidify.

  On top of that, spherical glass beads having a refractive index of 1.935 (wavelength: 589.3 nm) and a diameter of 50 μm are densely dispersed to soften the transparent adhesive layer and the colored adhesive layer in a thermostatic bath. Meanwhile, the transparent beads are pressed toward the transparent substrate by a pressure plate, and the beads are buried and fixed in the adhesive layer. The thickness of the adhesive layer after fixing the transparent beads was about 21 μm for both 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.

  A transparent and transparent optically isotropic acrylic plate having a thickness of 2 mm is bonded to the surface of the light distribution control element 100 on the transparent substrate 101 side, and a Fresnel lens is further arranged on the transparent bead 105 side so that a transmissive screen. The rear projection type display device as shown in FIG. 11 was realized by combining the projection device 701 and the mirror 702 using a polymer dispersion type liquid crystal element with the 703 as a two-dimensional optical switch element.

  When this rear projection type display device was evaluated, the polarization state of each color light projected from the projection device 701 was non-polarized and matched, and the light distribution characteristics of the light distribution control element 100 constituting the transmission screen 703 were polarized. High-quality images without coloring or stripes due to the dependency could be obtained. In addition, the isotropic viewing angle was as wide as ± 60 ° in both the horizontal and vertical directions.

Furthermore, since unnecessary light incident on the transmission screen from the outside is absorbed by the colored adhesive layer of the light distribution control element, the black light having a low luminance of 0.5 cd / m ² in a bright environment (vertical illuminance 300 lx). The display was realized and a high contrast ratio was obtained even in a bright environment.

  Note that as a two-dimensional optical switch element that does not use polarized light for display, US Pat. Nos. 5,610,409 and 5,083,857, or digital mirrors described in US patent application 08/161832, US patent application 08/171303, etc. A device (DMD) can be used.

  The DMD has an array of micromirrors corresponding to pixels twisted on a semiconductor substrate and supported by hinges, and an address electrode. When a voltage is applied to the address electrode, the micromirror is electrostatically attracted. Is to be deflected or rotated.

  Accordingly, when the incident light is reflected toward the projection lens, a bright display is obtained, and when the incident light is reflected toward the light absorbing means, a dark display is obtained. That is, since non-polarized light can be displayed, the transparent base material of the light distribution control element used as the transmissive screen is optically anisotropic as in the rear projection display device using the polymer dispersion type liquid crystal element. Even so, it is possible to obtain a high-quality image without coloring due to the polarization dependency of the light distribution characteristic or without a stripe pattern.

[Embodiment 5 of rear projection display device]
Next, another rear projection type display device of the present invention will be described. The rear projection display device described here includes a projection device 701, a mirror 702, and a transmission screen 703 as in the above-described embodiment described with reference to FIG. 11, and the projection light 704 emitted from the projection device 701 causes the mirror 702. The image is displayed on the transmissive screen 703 via the screen, but the configuration of the projection device 701 is different.

  One of the main points of the present invention is that image light incident on the light distribution control element 100 constituting the transmission screen 703 is substantially unpolarized. Therefore, in this embodiment, as the two-dimensional optical switch element, in addition to using a display element that can display non-polarized light, a depolarization means for depolarizing the light is disposed between the light distribution control element and the two-dimensional optical switch element. This has been achieved.

  As the depolarization means, an element that artificially creates various polarized light within the integration range such as wavelength width and time, and averages these to produce non-polarized light in terms of phase, so-called pseudo depolarizer is used. be able to.

  As the depolarizer, for example, a quartz plate having a refractive index anisotropy Δn = 0.09, a thickness of 2 mm and a thickness of 1 mm, cut and polished parallel to the optical axis, and the slow axes of 45 ° each other is formed. A Lyot depolarizer combined as described above can be used. If this depolarizer is used, it becomes a substantially complete depolarizer for white light. In addition, a polymer liquid crystal film or a retardation film in which d · Δn is sufficiently larger than the visible wavelength when the film thickness is d and the refractive index anisotropy is Δn are laminated, and the pseudo depolarizer is similarly configured. May be.

  Such a pseudo depolarizer is preferably disposed in the optical path after the light that has passed through the two-dimensional optical switch elements 807, 808, and 809 is color-combined as in the projection apparatus shown in FIG. FIG. 30 shows a projection apparatus using the TN liquid crystal display element described in the above embodiment, in which a pseudo depolarizer 3000 is newly arranged. As a result, optical image light whose polarization has been substantially eliminated can be projected onto the transmissive screen 703.

  That is, since the polarization state of each color light projected from the projection device 701 is substantially non-polarized and coincides, the color distribution due to the polarization dependence of the light distribution characteristic of the light distribution control element 100 is high, and there is no stripe pattern. An image can be obtained. Furthermore, since a transparent body having optical anisotropy may be used as the transparent base material 101 of the light distribution control element 100, the material selection range of the transparent base material 101 is widened, and a cheaper and stronger material is used. Is possible. In the above-described rear projection type display device, the two-dimensional optical switch element of the projection device has been described using a transmissive liquid crystal display element. However, the present invention is not limited to this, and a reflection type display element is used. There may be.

  In addition, the display mode is not limited to the TN mode, but a liquid crystal display element such as a VA (Vertical Aligned) mode, an ECB mode, an OCB mode, an STN (Super Twisted Nematic) mode, or a liquid crystal using a ferroelectric liquid crystal or an antiferroelectric liquid crystal. It may be a display element.

[Example 1 of liquid crystal display device]
FIG. 31 is a schematic cross-sectional view of a direct-view liquid crystal display device using the light distribution control element according to the present invention.

  The liquid crystal display device of the present invention includes a liquid crystal display element 1302, a backlight device 1301 provided on the back surface thereof, a polarizer 1204 and an analyzer 1214 disposed on the back surface and the front surface of the liquid crystal display element 1302, respectively, and a detector. It is comprised from the light distribution control element 100 of this invention provided in the front surface of the photon 1214.

  The backlight device 1301 can efficiently emit substantially parallel light. For example, a backlight assembly for an electro-optical display described in Japanese Patent Publication No. 9-505212 and International Publication No. WO95 / 14255. Can be used.

  Here, a light source 1201 composed of a cold cathode tube, a light guide 1202 composed of a transparent acrylic resin, and a backlight device composed of light collimating means 1203 were used.

  As the light collimating means 1203, a known element, for example, a quadrangular pyramidal microtaper rod array optically coupled to the light guide 1202 shown in FIG. 31 can be used. In this case, the light guided from the light guide 1202 is totally reflected once or more on the wall surface of the microtaper rod, and is made substantially parallel and emitted.

  As the light collimating means 1203, a microprism sheet or a microlens array can be used. By using a backlight device having such a light collimating element 1203, substantially collimated illumination light having a half-value angle within ± 10 ° can be obtained.

  The liquid crystal display element 1302 includes a first transparent substrate 1210 having a transparent electrode 1212 made of ITO and an alignment film 1211 made of polyimide polymer, an alignment film 1207, a transparent electrode 1206 forming a pixel, and a connection to the first transparent substrate 1210. The dielectric anisotropy enclosed between the second transparent substrate 1205 having a switching element such as a wiring and a thin film transistor (not shown) and the two transparent substrates 1212 and 1210 connected via the sealant 1208 is positive. And a liquid crystal layer 1209 made of nematic liquid crystal.

  In the liquid crystal display element 1302, the alignment films 1207 and 1211 applied to the two transparent substrates 1205 and 1210 are rubbed so that the liquid crystal molecular major axis of the liquid crystal layer 1209 is continuously between the two transparent substrates. A so-called TN liquid crystal display element twisted by 90 ° is formed.

  A polarizer 1204 and an analyzer 1214 are respectively disposed on the light incident surface and the light emitting surface of the liquid crystal display element 1302 so as to transmit linearly polarized light orthogonal to each other. As the polarizer 1204 and the analyzer 1214, a stretched PVA obtained by absorbing iodine and applying a TAC protective layer to both surfaces of a film provided with a polarizing function is used. The transparent substrate 1205 and the transparent substrate 1210 are each made of acrylic. Glue to be optically bonded with an adhesive.

  A light distribution control element 100 is disposed on the front surface of the analyzer 1214. As the light distribution control element 100, the element described in Example 1 of the light distribution control element was used. Here, the bonding with the analyzer 1214 is performed by the adhesive 1213 patterned so as to surround the display portion of the liquid crystal display element. However, the gap between the transparent beads of the light distribution control element 100 and the analyzer 1214 is formed on the entire surface. It may be bonded so as to be filled with a transparent adhesive having a low refractive index or a combination thereof.

  Next, the operation of the direct view liquid crystal display device will be described. Of the outgoing light 1215 from the backlight device 1301, linearly polarized light that has passed through the polarizer 1204 passes through the liquid crystal panel 1302 and enters the analyzer 1214. At this time, since the polarization state of the light transmitted through the liquid crystal panel 1302 changes depending on the electric field applied to the liquid crystal layer 1209, the electric field corresponding to the image information is applied to the liquid crystal layer 1209 to transmit the analyzer 1214. An image can be formed by controlling the amount of light. 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 converged and diverged by the refraction action.

  Here, a general TN liquid crystal display device has a viewing angle dependency, and when viewed from an oblique direction, a contrast ratio is lowered, gradation inversion, and color tone change occur. Therefore, good image quality can be obtained only in the vicinity of the front.

  Further, as described above, the light distribution control element 100 has low transmittance due to absorption by the colored adhesive layer when the incident angle of incident light increases. For this reason, among the light emitted from the liquid crystal display element 1302, most of the light having a large incident angle that causes a decrease in contrast ratio, gradation inversion, and color change is absorbed by the colored adhesive layer.

  On the other hand, light in the vicinity of the front with an incident angle of 0 °, which provides good image quality, is transmitted and isotropically diffused, so there is no color tone change or gradation inversion over a wide viewing angle range, and the contrast ratio A high image can be obtained.

  Further, in the present liquid crystal display device, the light emitted from the backlight device 1301 to the liquid crystal display element 1302 is substantially parallel light, and therefore, when the light amount ratio in the angle range in which good image quality can be obtained in the liquid crystal display element 1302 increases. At the same time, the light loss in the light distribution control element 100 is reduced and the light use efficiency is increased, so that an image with high brightness and high contrast can be obtained. In addition, since the light distribution control element 100 has a high effect of reducing stray light due to unnecessary external light, low luminance black display is realized even in a bright environment, and an image with a high contrast ratio can be obtained.

  When the liquid crystal display device having the above-described 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 with a contrast ratio of 100: 1 or more was obtained.

  Normally, in the TN liquid crystal display device, the transmission axis of the linearly polarized light of the polarizer and the analyzer forms an angle of 45 ° with respect to the horizontal direction of the display surface in order to ensure the symmetry of the contrast ratio in the horizontal direction. It is common to arrange.

  However, in the liquid crystal display device of the present invention, a wide viewing angle is obtained by isotropically diffusing image light in the vicinity of a viewing angle of 0 ° at which good image quality can be obtained. Therefore, the polarizer 1204 and the analyzer 1214 are obtained. Even if the linearly polarized light transmission axis is not 45 ° or 135 ° with respect to the horizontal direction of the display surface, the symmetry of the contrast ratio is maintained. Rather, the linearly polarized light transmission axis of the analyzer 1214 is arranged so as to substantially coincide with the horizontal direction of the display surface of the liquid crystal display element 1302 because of the polarization dependence of the light distribution characteristics of the light distribution control elements constituting the liquid crystal display device. Should do.

  That is, as shown in the schematic diagram of FIG. 32, the linearly polarized light transmission axis of the polarizer 1204 is arranged in a direction perpendicular to the display surface of the liquid crystal display device, and the linearly polarized light transmission axis of the analyzer 1214 is the same as that of the liquid crystal display device. It is arranged horizontally with respect to the display surface. Therefore, the alignment direction of the liquid crystal is also learned, the alignment direction of the liquid crystal on the transparent substrate 1205 side is a direction perpendicular to the liquid crystal display device display surface, and the alignment direction of the liquid crystal on the transparent substrate 1210 side is the liquid crystal display device display surface. The orientation direction of the liquid crystal on the transparent substrate 1205 side is the horizontal direction with respect to the display surface of the liquid crystal display device, and the orientation direction of the liquid crystal on the transparent substrate 1210 side is perpendicular to the display surface of the liquid crystal display device And

  With the above configuration, the light incident on the light distribution control element 100 becomes linearly polarized light having a horizontal vibration direction with respect to the display surface. In this case, due to the polarization dependence of the light distribution characteristics of the light distribution control element 100 as described above, a liquid crystal display element having a wider viewing angle in the horizontal direction than in the vertical direction of the display surface and a symmetrical brightness can be obtained. . This is very effective in efficiently distributing the limited light to the observer because a display device generally requires a wider viewing angle in the horizontal direction than in the vertical direction.

[Example 2 of liquid crystal display device]
FIG. 33 is a schematic cross-sectional view of another direct-view type liquid crystal display device of the present invention. In this liquid crystal display device, a phase difference plate 3100 is arranged between the analyzer 1214 and the light distribution control element 100 in the liquid crystal display device shown in FIG.

  As described above, the light distribution control element 100 constituting the present liquid crystal display device can change its light distribution characteristic, that is, the viewing angle, depending on the polarization state of incident light. The retardation plate 3100 has a function of converting linearly polarized light transmitted through the analyzer 1214 into polarized light capable of obtaining a desired viewing angle by utilizing this property.

  For example, when a quarter wave plate is used as the retardation plate 3100, the linearly polarized light transmitted through the analyzer 1214 becomes substantially circularly polarized light by the action of the retardation plate 3100, and enters the light distribution control element 100, and is horizontal. In the vertical direction, the same isotropic and wide viewing angle can be obtained.

  In addition, in order to obtain left-right symmetry of the contrast ratio as in a general TN liquid crystal display device, the transmission axes of the linearly polarized light of the analyzer 1214 and the polarizer 1204 are arranged at 45 ° or 135 ° with respect to the horizontal direction. As the phase difference plate 3100, for example, a half-wave plate is arranged with its slow axis inclined 22.5 ° with respect to the transmission axis of the analyzer, and the incident light to the light distribution control element 100 is linearly changed. You may make it convert so that the vibration direction of polarized light may become a horizontal direction with respect to a display surface.

  In this case, the liquid crystal display element having a wide viewing angle in the horizontal direction and a symmetric brightness can be obtained by simply adding the phase difference plate 3100 and the light distribution control element 100 to the existing liquid crystal display element. Can be obtained. In general, a display device is required to have a wider viewing angle in the horizontal direction than in the vertical direction, which is very effective in efficiently distributing the limited light to the observer.

  Note that the same effect can be obtained by arranging a polymer laminated film having a twisted structure instead of the retardation plate 3100. Such a polymer laminated film is realized, for example, by laminating four retardation films of PC film having a retardation d · Δn = 275 nm, and the four retardation films are formed from a phase closer to a liquid crystal display element. The axes may be arranged at 5.6 °, 16.9 °, 28.1 °, and 39.4 ° with respect to the transmission axis of the analyzer.

  In the above embodiment, in order to make the drawing easy to see, an example of a TN liquid crystal panel for monochrome display is shown as the liquid crystal display element. However, a full color display liquid crystal display element in which a micro color filter is applied to a transparent substrate may be used. Needless to say.

  The display mode is not limited to the TN mode, and a liquid crystal panel such as a VA mode, an ECB mode, an OCB mode, or an STN mode may be used. Further, the driving method may be direct matrix driving in addition to active matrix driving with a switching element such as a thin film transistor.

It is a schematic cross section of the light distribution control element of this invention. It is a model perspective view of the light distribution control element of this invention. It is a schematic cross section explaining an example of the manufacturing method of the light distribution control element of this invention. It is an isoluminance diagram which shows the light emission (light distribution) characteristic at the time of the polarization | polarized-light incidence of the conventional light distribution control element. It is explanatory drawing of the coordinate system of an isoluminance diagram. It is explanatory drawing of the circular contact cross section of a refractive index ellipsoid. It is explanatory drawing of the optical axis of a polyethylene terephthalate film. It is a graph which shows the relationship between the light incident angle of a polyethylene terephthalate film, and energy transmittance. It is an isoluminance diagram showing the light emission characteristic at the time of linearly polarized light incidence of the light distribution control element of the present invention. It is a graph which shows the light emission (light distribution) characteristic at the time of the linearly polarized light incidence of the light distribution control element of this invention. It is a schematic cross section of the rear projection type display device of the present invention. It is a schematic cross section of the projection apparatus which concerns on the rear projection type display apparatus of this invention. It is a schematic cross section of the two-dimensional optical switch of the projection apparatus which concerns on the rear projection type display apparatus of this invention. It is a schematic cross section of the transmissive screen concerning the rear projection type display apparatus of this invention. It is a schematic diagram for demonstrating the light incident angle dependence of the transmittance | permeability of the light distribution control element of this invention. It is a graph which shows an example of the relationship between the transmittance | permeability of the light distribution control element of this invention, and a light incident angle. It is a schematic cross section of the polarization state alignment means used for the projection apparatus which concerns on the rear projection type display apparatus of this invention. It is a schematic diagram for operation | movement description of the polarization state alignment means used for the projection apparatus which concerns on the rear projection type display apparatus of this invention. It is a schematic cross section of the projection apparatus which concerns on the rear projection type display apparatus of this invention. It is a schematic cross section of the polarization state conversion element used for the projection apparatus which concerns on the rear projection type display apparatus of this invention. It is a schematic diagram for operation | movement description of the polarization state conversion element used for the projection apparatus which concerns on the rear projection type display apparatus of this invention. It is a schematic diagram for operation | movement description of the polarization state conversion element used for the projection apparatus which concerns on the rear projection type display apparatus of this invention. It is a schematic diagram for operation | movement description of the polarization state conversion element used for the projection apparatus which concerns on the rear projection type display apparatus of this invention. It is a schematic diagram for operation | movement description of the polarization state conversion element used for the projection apparatus which concerns on the rear projection type display apparatus of this invention. It is a schematic cross section of the polymer dispersion type liquid crystal display element of the projection apparatus which concerns on the rear projection type display apparatus of this invention. FIG. 5 is a schematic diagram for explaining the operation of a polymer dispersion type liquid crystal display element. It is a schematic diagram for explanation of an optical system that performs display by a polymer dispersion type liquid crystal display element. It is a schematic diagram for explanation of an optical system that performs display by a polymer dispersion type liquid crystal display element. It is a schematic cross section of the projection apparatus which concerns on the rear projection type display apparatus of this invention. It is a schematic cross section of the projection apparatus which concerns on the rear projection type display apparatus of this invention. It is a schematic cross section of the liquid crystal display device of this invention. It is a schematic diagram for description of the linearly polarized light transmission axis of the polarizer and analyzer of the liquid crystal display device of the present invention. It is a schematic cross section of the liquid crystal display device of this invention. It is a model perspective view of the light distribution control element of this invention. It is a model perspective view of the light distribution control element of this invention. It is a schematic cross section showing an example of a lenticular lens sheet. It is a model perspective view which shows an example of a lenticular lens sheet. It is a schematic cross section showing an example of a conventional transmission screen. It is a perspective view of the conventional transmissive screen. It is a model perspective view of the rear projection type display apparatus of this invention. It is explanatory drawing which illustrates the area | region divided by the observer detection part of the rear projection type display apparatus of this invention. It is explanatory drawing which illustrates the area | region divided by the observer detection part of the rear projection type display apparatus of this invention. It is a figure for demonstrating the effect of the rear projection type display apparatus of this invention. It is a figure for demonstrating the effect of the rear projection type display apparatus of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 ... Light distribution control element, 101 ... Transparent base material, 102 ... Transparent adhesive layer, 103 ... Colored adhesive layer, 104 ... Adhesive layer, 105 ... Transparent bead, 106 ... Incident light, 107 ... (External) unnecessary light 701: Projection device, 702: Mirror, 703: Transmission type screen, 704 ... Projection light, 801 ... Light source, 802, 803 ... Dichroic mirror, 804, 805, 806 ... Total reflection mirror, 807, 808, 809 ... Liquid crystal display Element, 811 ... Color synthesis cross dichroic prism, 812, 813, 814 ... Polarization state alignment means, 815 ... Polarization state conversion element, 901, 902 ... Transparent glass substrate, 903, 904 ... Transparent electrode, 905, 906 ... Alignment film, 907 ... Liquid crystal layer, 908 ... Sealing agent, 909 ... Polarizer, 910 ... Analyzer, 801f ... Fresnel lens, 3401 ... Fine Bright rod, 1001, 1002 ... Transparent substrate, 1301 ... Backlight device, 1302 ... Liquid crystal display element, 1003, 1004 ... Alignment film, 1005 ... Sealing agent, 1006 ... Liquid crystal layer, 911, 912, 1007, 1008 ... Liquid crystal orientation direction , 1201 ... light source, 1202 ... light guide, 1203 ... light collimating means, 1204 ... polarizer, 1214 ... analyzer, 1215 ... emitted light, 2501, 2502 ... transparent glass substrate, 2503, 2504 ... transparent electrode, 2505 ... Polymer dispersed liquid crystal layer, 2506 ... liquid crystal droplet, 2507 ... polymer, 2801 ... light source, 2701 ... lens, 2500 ... polymer dispersed liquid crystal element, 2803, 2817 ... aperture, 2813, 2814, 2815 ... polymer dispersed liquid crystal element, 2819 ... Projection lens, 3501 ... transparent substrate, 3502 ... micro lens, 350 ... light absorption layer, 3100 ... retardation plate, 4001 ... rear projection display, 4002 ... observer sensing unit, 4100 ... observer, 3000 ... pseudo depolarizer.

Claims (11)

A projection type apparatus comprising: a transmissive screen; a light source; a plurality of optical switch elements that modulate light from the light source; and a projection lens that projects light modulated by the optical switch element onto the transmissive screen. And having polarization state alignment means for substantially matching polarization states of polarized light modulated by each of the plurality of optical switch elements when projected onto the transmission screen, the transmission screen comprising a transparent substrate A light distribution control element comprising: a plurality of microlenses having a light collecting action disposed on one surface of the transparent substrate; and a light absorption layer having an opening at a light converging portion of the microlens. The transparent base material is composed of an optically isotropic transparent body , and the maximum difference in phase difference due to the difference in the traveling angle of light passing through the transparent base material after passing through the microlens. Value is 1 Rear projection display device, characterized in that at two wavelengths less.   2. The rear projection display device according to claim 1, wherein the transmissive screen includes the transparent base material and a minute lens formed on a surface of the transparent base material on which the polarized light is incident.   The rear projection display device according to claim 1, wherein the transmissive screen has a black light absorption layer in which an opening is formed.   The rear projection display device according to claim 2, wherein the minute lens has a rod shape.   The rear projection display device according to claim 2, wherein the minute lens is spherical.   The rear projection display device according to claim 1, wherein a polarization state of the polarized light when projected onto the transmissive screen is circularly polarized light.   The rear projection display device according to claim 1, wherein a polarization state of the polarized light when projected onto the transmissive screen is elliptically polarized light.   The rear projection display device according to claim 1, wherein a polarization state of the polarized light when projected onto the transmissive screen is linearly polarized light. A projection device for projecting an optical image; and projection light from the projection device is incident from the back surface, and a transmissive screen for displaying the incident projection light on the front surface. A single-tube projection apparatus having a plurality of two-dimensional optical switch elements that modulate light from a light source into an optical image according to image information, and a projection lens that magnifies and projects the modulated optical image, the transmission type The screen has a transparent substrate, a plurality of microlenses having a light collecting action formed on one surface of the transparent substrate, and a light absorption layer having an opening at a focal position of the microlens , wherein the transparent substrate has a light distribution control device constituted by optically substantially equal towards a transparent body, and a light beam collimating means provided projecting Shako incident side of the light distribution control device, the two-dimensional An optical switch element is a liquid that performs display using polarized light. A display device, comprising means aligning polarization direction of the transmission axis of the linear polarization of the analyzer to substantially coincide with each other in the liquid crystal display device, the progress of the light passing through the transparent substrate after having passed through the micro lens A rear projection display device characterized in that the maximum value of the difference in phase difference due to the difference in angle is ½ wavelength or less. The rear projection display device according to claim 9 , wherein the direction of the transmission axis of the linearly polarized light of the analyzer of the liquid crystal display element is horizontal or perpendicular to the display surface. The rear projection display device according to claim 9 , wherein the micro lens has a rod shape and is directly formed on the transparent substrate.

Images