JP2004046243A - Projection display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projection display device which is high in the effect of reducing the stray light by external unnecessary light of a liquid crystal display device etc., and is bright when an observer views the device from any angles, and which eliminates the stripe patterns produced when the polarized light of a light distribution control element having wide visual field angle characteristics is made incident thereon. <P>SOLUTION: The light distribution control element (100) comprises a transparent base material (104), a plurality of microlens arrays (transparent beads 105) densely arranged on the surface of the transparent base material and a light absorption layer having microapertures in the approximate focal positions of the microlenses, in which the transparent base material is composed of an approximately optically isotropic transparent body or uniaxially optically anisotropic transparent body. <P>COPYRIGHT: (C)2004,JPO

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.

Demand for rear projection display devices is increasing, especially in the North American market, because large-screen displays can be realized relatively easily at a small size and at low cost as compared with direct-view CRTs. In particular, a rear-projection display device having a projection device using a liquid crystal display device such as a TN (Twisted Nematic) liquid crystal as a two-dimensional optical switch device is different from a rear-projection display device using a CRT projection tube in dot matrix display. It 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 sectional view of a rear projection type display device. 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 transmissive screen 703 generally includes a Fresnel lens sheet 1402 and a lenticular lens sheet 1401, and the Fresnel lens sheet 1402 is an optical component having the same function as a convex lens. Is bent to the observer side to expand the suitable viewing range.

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

FIG. 36 is a schematic 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-shaped lenses 1501 are arranged in one direction, and a black stripe 1502 is provided in a portion other than the light converging portion. By doing so, the configuration is such that there is ideally no loss of projection light and a decrease in contrast ratio with respect to external light can be suppressed.

Generally, a lenticular lens is arranged so that its generatrix is 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 by the diffusion material mixed in the base material of the lenticular lens or on the surface portion, so that the viewing angle in the vertical direction is considerably narrower than that in the horizontal direction. In addition, since the lenticular lens has linear lenses arranged regularly, moire interference fringes are likely to occur in an image.

On the other hand, Patent Document 1 discloses a transmission screen having a configuration in which a spherical lens 1602 is spread over a transparent substrate 1601 as shown in FIG. 39 and fixed with a transparent resin. In this configuration, since a mold is not used, there is no limitation on the size in manufacturing, and a large-screen transmissive screen without any seams can be realized. Further, 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 horizontal and vertical directions.

Further, Non-Patent Document 1 discloses a screen having a structure in which optical beads are fixed on a transparent substrate via a light-absorbing adhesive layer, and the surface of the optical beads opposite to the transparent substrate is transparently back-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, similarly to the above-mentioned Patent Document 2, the lens effect of the beads makes it possible to obtain an isotropic viewing angle that is wide in both the horizontal and vertical directions. Further, unnecessary light incident from the outside is absorbed by the light absorbing adhesive layer (or the colored hot melt adhesive layer), so that a high contrast ratio can be obtained even in a bright environment. Also, high resolution can be realized relatively easily by reducing the diameter of the beads.

JP-A-2-77736

JP-A-9-318801 SID94 DIGEST pp 741-744 (A Novel High-Resolution Ambient-Light-Rejecting Rear-ProjectionScreen)

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

Spherical glass transparent beads having a refractive index of 1.935 (wavelength 589.3 nm) and a diameter of 50 μm are densely dispersed and disposed thereon, and the transparent adhesive layer and the colored adhesive layer are heated and softened in a thermostat. Next, the transparent beads were pressed against the transparent substrate side by a pressure plate to be buried and fixed in the colored adhesive layer and the transparent adhesive layer. The thickness of the adhesive layer after fixing was about 21 μm in total of the transparent adhesive layer and the colored adhesive layer, and about 58% of the diameter of the transparent beads was exposed from the adhesive layer.

When the produced light distribution control element was evaluated as a transmissive screen of a rear projection display apparatus equipped with a projection apparatus using a TN type liquid crystal display element as a two-dimensional optical switch element (light valve), it was evaluated in both the horizontal and vertical directions. A wide viewing angle of ± 50 ° or more (in this case, an angle at which the luminance becomes 1/2 of the front luminance) can be obtained, and unnecessary light incident on the light distribution control element from the outside (observer side) is colored. Absorbed by the adhesive layer, low-luminance black display was realized even in a bright environment.

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

An object of the present invention is to provide a light distribution control element which does not cause deterioration in image quality due to the occurrence of the above-mentioned 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 conducted a more detailed study on the above-mentioned conventional light distribution control element in order to investigate the causes of the occurrence of a stripe pattern and a change in chromaticity. As a result, the stripe pattern is generated when polarized light is incident on the light distribution control element, and a different phase difference occurs in light traveling at different angles in the transparent substrate due to the optical anisotropy of the transparent substrate, Further, they have found that the difference in energy transmittance between the p-polarized light component and the s-polarized light component of the light emitted from the transparent substrate is generated in combination. Further, the present inventors have found that the light distribution characteristics of the present light distribution control element change depending on the polarization state of incident light, and this causes a change in chromaticity. The gist of the present invention reached on the basis of the above is as follows.

[1] Light distribution including a transparent base material, a large number of microlenses densely arranged on one surface of the transparent base material, and a light absorbing layer having a fine opening at a substantially focal position of the microlens. The light distribution control element, wherein the transparent substrate is made of an optically isotropic transparent body or a uniaxial optically anisotropic transparent body.

By using this, the occurrence of a stripe pattern when polarized light is incident is suppressed by suppressing the occurrence of a phase difference that affects the image quality.

[2] A projection device that projects an optical image, and a projection light from the projection device is incident from the back, and a rear projection display device including a transmission screen that displays the projection light on the front,
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 single-tube projection device that has a projection lens that enlarges and projects the modulated optical image. ,
When the modulated optical image emitted from the projection device enters the transmissive screen, the polarization state of the optical image light formed by the two-dimensional optical switch element is substantially matched over the entire visible wavelength range. Having means,
The transmission screen includes a transparent substrate, a large number of minute lenses densely arranged on one surface of the transparent substrate, and a light absorbing layer having a minute opening at a substantially focal position of the minute lens. A light distribution control element in which the transparent substrate is made of an optically substantially isotropic transparent body, or a uniaxial optically anisotropic transparent body, and provided on the incident light incident side of the light distribution control element. A rear projection display device comprising a light beam collimating means.

According to the 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 characteristics of the light distribution control element does not occur, and a high-quality display with no change in chromaticity even when viewed from an oblique direction can be realized.

Furthermore, since the image light incident on the light distribution control element is substantially parallel and incident at an incident angle of substantially 0 °, a decrease in transmittance at the light distribution control element is suppressed and a bright display image is obtained. 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 state of the optical image light formed by the two-dimensional optical switch element is determined by the oscillation direction of the electric vector. The above rear projection display device comprising a polarization state converting means for converting any one of linear polarized light in a horizontal direction, linear polarized light in a vertical direction, circular polarized light, and elliptically polarized light with respect to a transmission 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 improved without changing the configuration of the transmission screen due to the polarization dependence of the light distribution characteristic of the light distribution control element. A rear projection display device that can be easily changed can be realized.

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

According to the above, it is possible to automatically determine the position of the observer and change the polarization state of the projection light based on the position information to obtain a viewing angle characteristic corresponding to the position of the observer. In other words, the viewing angle characteristics are automatically changed according to the position of the observer, and the limited image light is effectively distributed to the observer to provide a good image to the observer.

[5] The single-tube type projection system 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 enlarges and projects the modulated optical image. Equipment,
The transmission screen includes a transparent substrate, a large number of minute lenses densely arranged on one surface of the transparent substrate, and a light absorbing layer having a minute opening at a substantially focal position of the minute lens. A light distribution control element, comprising light flux collimating means arranged on the incident side of the light distribution control element;
A rear-projection display device, comprising: a depolarizing unit that makes the projection light emitted from the projection device and incident on the transmission screen substantially non-polarized.

According to the above, since the optical image light incident on the light distribution control element constituting the transmission screen is non-polarized, the chromaticity does not change due to the polarization dependence of the light distribution characteristic of the light distribution control element. In addition, a striped pattern generated upon incidence of polarized light does not occur due to the optical anisotropy of the transparent substrate of the light distribution control element, so that a beautiful image without image quality degradation can be obtained. Further, even if a transparent material having optical anisotropy is used as the transparent substrate, there is no deterioration in image quality. Therefore, the selection range of the material is widened, and a transmissive screen comprising a light-intensity light distribution control element at a lower cost is used. Can be realized.

[6] A pair of transparent substrates in which a transparent electrode and an alignment film are laminated and formed, 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; A voltage applying means for applying a voltage corresponding to an image signal, and a liquid crystal display device in which a polarizer and an analyzer are arranged on a light incident surface side and a light emission surface side of the pair of transparent substrates,
A backlight device that emits substantially parallel light is arranged on the back surface of the pair of transparent substrates,
On the light emitting surface side of the pair of transparent substrates, a transparent substrate, a large number of minute lenses densely arranged on one surface of the transparent substrate, and a minute opening at a substantially focal position of the minute lens. Comprising a light-absorbing layer having, wherein the transparent substrate is an optically substantially isotropic transparent body, or a light distribution control element formed of a uniaxial optically anisotropic transparent body. Liquid crystal display.

Accordingly, only light in a limited range near the front where good image quality is obtained can be isotropically diffused by the light distribution control element, so that there is no color tone 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 arranged on the light incident surface of the pair of transparent substrates, an analyzer and a light distribution control element are arranged on the light emitting surface in order from the transparent substrate side, and further, a transmission axis of linearly polarized light of the analyzer. Wherein the liquid crystal display device is disposed horizontally with respect to the display surface.

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

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

Thereby, the polarization state of the light incident on the light distribution control element can be arbitrarily changed by the phase plate arranged between the analyzer and the light distribution control element, so that the light distribution control element can be changed only by changing the phase difference plate. A desired viewing angle can be obtained by utilizing the polarization dependence of the light distribution characteristics.

As described above, the light distribution control element of the present invention is optically substantially isotropic as a transparent substrate, or, by using a uniaxially anisotropic transparent body having an in-plane optical axis, to enter polarized light. Also, there is an effect that the image quality is not deteriorated due to the occurrence 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 enlarging means of a display device utilizing polarization such as a liquid crystal display device.

Further, the rear projection type display device of the present invention is configured such that the transmission type screen is constituted by the light distribution control element of the present invention and a Fresnel lens arranged on the light incident side thereof, and the projection screen of the projection light incident on the light distribution control element is formed. By setting the incident angle to 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 type projection device as the projection device, color shift or coloring caused by the dependence of the light distribution control element on the light incident angle does not occur, so that a high-quality image can be obtained.

Further, in the rear projection type display device of the present invention, the coloring state caused by the polarization dependence of the light distribution characteristics of the light distribution control element is eliminated by matching the polarization state of the projection light emitted from the projection apparatus with each color light. And high-quality images can be obtained.

In addition, the light distribution control element has a bright and wide viewing angle characteristic from any angle, and has a high effect of reducing stray light due to external unnecessary light. The display of the ratio can be realized.

Further, in the rear projection display device of the present invention, a substantially concentric microlens is used as a microlens of the light distribution control element, and a polarization state conversion element capable of changing the polarization state of light projected on the transmission screen is provided. This has the 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 in the rear projection display device, observer position determining means that determines a horizontal and vertical position of the observer based on a sensing signal of the sensing unit, By adding a control signal output unit that outputs a control signal to the polarization state conversion element based on the information of the determination unit, the position of the observer is automatically determined to change the polarization state of the projection light, and the position of the observer is changed. It is possible to obtain a viewing angle characteristic according to. That is, the viewing angle characteristic automatically changes 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 any position. This has the effect.

Further, in the rear projection display device of the present invention, by making the projection light from the projection device incident on the transmission type screen unpolarized, coloring due to the polarization dependence of the light distribution characteristics of the light distribution control element, or stripes It is possible to obtain a high-quality image without any problem.

In this case, as the transparent base material of the light distribution control element, a material having optical anisotropy may be used, so that the selection range of the material is widened, and a transmissive screen using a less expensive and high strength material is used. 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 front surface side, and the device that emits illumination light substantially parallel to the backlight device is used, so that the light in the range near the front is used. Since only the light distribution control element can diffuse isotropically, a liquid crystal display device having an image with a high contrast ratio without color tone change or gradation inversion over a wide viewing angle range 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 in 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 light incident on the light distribution control element can be arbitrarily changed by a phase difference plate disposed between the analyzer and the light distribution control element. In this way, a predetermined viewing angle can be obtained by utilizing the polarization dependence of the light distribution characteristics of the light distribution control element.

実 施 An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic 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 base material 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 may be a plate-shaped substrate having rigidity itself, or may be a film-shaped substrate. However, the substrate is optically substantially isotropic, or has 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.

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

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

As the transparent beads 105, glass or optically isotropic transparent resin spherical beads are used, and the higher the refractive index, the larger the refraction angle of light incident on the transparent beads. Has a wider light emission angle (viewing angle). However, the brightness at the front is reduced by that much, and the reflection at the surface and the reflection at the interface between the transparent substrate 101 and the air are increased, so that the total light transmittance is reduced.

Also, in order to efficiently transmit light to the opening on the light emitting surface side of the transparent beads 105, that is, the contact portion between the transparent beads 105 and the transparent adhesive layer 102, the light incident on the transparent beads on the light emitting surface side 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 emitting 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.

(4) The refractive index of the transparent beads 105 is selected based on these conditions so as to conform to the characteristics required for the light distribution control element, that is, the specifications of the viewing angle and the brightness (gain). Further, if necessary, a mixture of transparent beads having different refractive indexes can be used.

In the case where the light distribution control element 100 is used as a screen of a display device or a viewing angle enlarging means, 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 to a diameter smaller than the diameter of the transparent beads 105. Therefore, the diameter of the transparent beads needs to be smaller than the pixel of the image to be displayed on the light distribution control element.

To obtain high resolution, the smaller the diameter of the transparent beads 105 is, the better. However, when the diameter of the transparent beads 105 approaches the wavelength region of light, the scattering factor of transmitted light increases and the brightness and transmittance in front decrease. The self and its lower limit are defined.

直径 The diameter of the transparent beads 105 is １ ／ or less of the pixel pitch of the display image, and is preferably about 20 to 100 μm in practice. Further, in order to arrange the transparent beads 105 uniformly and at the maximum density on the surface of the transparent substrate 101, it is desirable that the dispersion of the particle diameter is as small as possible. Actually, the function as the light distribution control element is satisfied if the variation of the particle size is kept within 10%.

透明 Further, the transparent beads 105 are desirably free of air bubbles because air bubbles inside the transparent beads 105 cause a reduction in transmittance.

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

Step (a): A hot-melt transparent adhesive, which is heated and melted on a transparent substrate 101, or dissolved in a solvent, or dispersed in a colloidal form in a solution, is spin-coated, knife-coated, roll-coated, spray-coated, for example. Then, a transparent adhesive layer 102 is formed by coating with a blade coat.

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. Decrease temperature. Further, when 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 or solidified by a dryer to solidify or semi-solidify.

Step (c): A plurality of transparent beads 105 are dispersed and arranged on the colored adhesive layer 103 so as to have a maximum packing density of at least one. At this time, since the colored adhesive layer 103 has no adhesive property in a solidified or semi-solidified state, the transparent beads 105 can be dispersed and arranged at the maximum filling density relatively easily.

Next, the above is heated by a heating means such as a thermostat, an infrared heater, etc., so that the hot melt adhesive layer 104 is softened and melted. 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.

The depth of the transparent beads 105 buried in the hot melt adhesive layer 104 is desirably such that 50 to 80% of the diameter of the beads is exposed. If the amount of exposure is smaller than this, the amount of light incident on the transparent beads 105 decreases due to absorption by the colored adhesive layer, and the transmittance decreases. On the other hand, if the exposure amount is larger than this, the fixation of the beads becomes insufficient.

As described above, in the light distribution control element of the present invention, the transparent beads 105 are dispersed and arranged in one layer at almost the maximum packing density, and at least 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 operation of the light distribution control element of the present invention will be described with reference to FIG. As described above, in the light distribution control element 100, one layer of the transparent beads 105 is dispersed and arranged at almost the maximum packing density on the light incident surface side, and more than half of the bead diameter is incident from the hot melt adhesive layer 104. It is exposed and fixed on 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 is incident on the transparent beads 105. I do. The incident light is converged by the refraction effect of the transparent beads 105, passes through an opening formed at a contact portion between the transparent beads 105 and the transparent adhesive layer 102, and passes through the transparent substrate 101 and emits while diverging. . In other words, the light incident on the transparent beads is converged by the lens effect of the transparent beads and diverges isotropically, so that a light distribution control element having an isotropic and wide viewing angle can be obtained.

{Circle around (4)} Unnecessary light 107 entering from the outside is absorbed by the colored adhesive layer 102, and the unnecessary light is not observed as stray light. Therefore, even in a bright environment, the effect of reducing stray light due to external unnecessary light is high, and a light distribution control element that is bright even when viewed from any angle by an observer and has isotropic viewing angle characteristics can be obtained.

[Elimination of stripe pattern when polarized light is incident]
Next, in order to clarify the effect peculiar to the light distribution control element of the present invention, a description will be given of the occurrence of a stripe pattern which appears when obliquely observed when polarized light is incident, which is a conventional problem.

FIG. 4 is a graph showing the light emission characteristics of a conventional light distribution control element (with no consideration given to the problem of the present invention) at the time of incidence of polarized light in an isoluminance diagram.

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

(4) As shown in FIG. 4, in the conventional light distribution control element, when polarized light is incident, a substantially concentric luminance fluctuation appears around two points near an emission angle of 40 °. This can actually be visually recognized as a stripe pattern when observed from an oblique direction.

従 来 The conventional light distribution control element used in this measurement used a flat polyethylene terephthalate (PET) film having a thickness of 120 μm 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 color adhesive layer 4.5 μm formed by blending 10 parts by weight of carbon black with the polyester hot melt adhesive is formed thereon. Spherical glass transparent beads having a ratio of 1.935 (wavelength 589.3 nm) and a diameter of 50 μm are densely dispersed and buried and fixed in the adhesive layer.

(4) The thickness of the adhesive layer after fixing the transparent beads was about 21 μm in total of the transparent layer and the coloring layer, and about 58% of the diameter of the transparent beads was exposed from the adhesive layer.

Here, in the light distribution controlling element, a biaxially stretched PET film was used as the transparent substrate 101. This is because the properties of the biaxially stretched film are remarkably improved, for example, the tensile strength and impact strength are increased as compared with the unstretched film, and the transparency and the operating temperature range are also improved. Further, the PET film has good adhesiveness with a polyester-based hot-melt adhesive having good adhesiveness with glass transparent beads, and has good solvent resistance to the hot-melt adhesive (solvent: toluene). is there.

For the above reasons, a biaxially stretched PET film was used as the transparent substrate, but generally, the biaxially stretched film has three main refractive indices (direction perpendicular to the film surface: Z-axis direction, parallel to the film surface, and orthogonal to each other). (Direction: X-axis direction and Y-axis direction).

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

Since the light that has traveled along the optical axis in the PET film is refracted at the interface with air and exits at an exit angle of 41.6 °, the approximate center position of the luminance variation near the exit angle of 40 ° shown in FIG. This corresponds to the optical axis.

Here, consider a case where light of a specific polarization state (linearly polarized light or elliptically polarized light) enters 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 light traveling along the optical axis in the PET film has no phase difference, 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 angle shift, the state of polarization, that is, the p-polarized light component parallel to the light incident surface at the PET film light emission side interface. , The ratio of the vertical s-polarized light component changes. In other words, for light traveling in a direction different from the optical axis direction, light having a large amount of p-polarized component and light having a large amount of s-polarized component appear alternately in accordance with the magnitude of deviation from the optical axis.

Here, the refraction of the dielectric surface generally 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.

の As shown in FIG. 8, there is a maximum transmittance difference of 30% or more between p-polarized light and s-polarized light. Therefore, there is a difference in the amount of transmitted light between light having a large amount of p-polarized light component and light having a large amount of s-polarized light component, and bright and dark brightness is formed, which is visually recognized as a stripe pattern.

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

光 The light distribution control element of the present invention is characterized in that the transparent base material 101 is substantially optically isotropic or has a uniaxial anisotropy having an optical axis parallel to the film surface. Therefore, the polarized light incident on the present light distribution control element is converged by the transparent beads and travels at various angles in the transparent substrate while diverging. However, since the transparent substrate is optically isotropic, it depends on the traveling angle. No difference in phase difference occurs, and the polarization state, that is, the ratio between the p-polarized component and the s-polarized component hardly changes depending on the output angle, so that no stripe pattern occurs.

When the polarized light incident on the light distribution control element is linearly polarized light, if the transparent substrate is a uniaxially anisotropic substance having an in-plane optical axis, the oscillation direction of the electric vector of the incident linearly polarized light is determined by a transparent substrate. By making the material parallel or perpendicular to the slow axis of the material, it is possible to reduce the difference in the phase difference due to the advancing angle of the polarized light passing through the transparent substrate, and to suppress the occurrence of a stripe pattern.

Furthermore, even if the transparent substrate has optical anisotropy, the difference in the phase difference depending on the traveling angle of light traveling in the transparent substrate is small, and the change in the polarization state is small. 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 base material is 以下 wavelength or less, the change in the polarization state due to the angle of the light passing through the transparent base material is the largest. However, since the light having the p-polarized component of 100% is merely converted into the light having the s-polarized component of 100%, the change in the brightness is hardly visually recognized.

More ideally, it is desirable to keep the maximum value of the difference in the phase difference depending on the angle of the light passing through the inside of the transparent substrate to １ ／ wavelength or less. In this case, at the maximum, for example, the light of 100% of the p-polarized light component is converted into the light of the 50% of the p-polarized light component and the 50% of the s-polarized light component.

Therefore, the optically isotropic transparent substrate referred to herein is different from the optically substantially isotropic transparent substrate in that the difference in the phase difference due to the difference in the traveling angle of the light traveling in the transparent substrate is small, so that the change in the polarization state is small and the luminance is low. A material showing isotropicity to the extent that no change is observed.

As described above, in the light distribution control element of the present invention, since a transparent substrate is optically substantially isotropic, or a uniaxially anisotropic transparent body having an in-plane optical axis, polarized light is incident. Also, the image quality is not degraded due to the occurrence of the stripe pattern, and a wide viewing angle can be obtained.

{Circle around (2)} Since the unnecessary light 107 entering the light distribution control element 100 from the outside is absorbed by the colored adhesive layer 102, the unnecessary light is not observed as stray light. Therefore, stray light due to external unnecessary light is reduced even in a bright environment.

As described above, since the energy transmittance of the dielectric surface is different between p-polarized light and s-polarized light, the transmittance of the p-polarized component is high on the surface of the transparent beads 105 or the transparent substrate 101, and the light of the s-polarized component is high. 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 present light distribution control element, the viewing angle in a direction parallel to the vibration direction of the electric vector of the linearly polarized light is wider than in a direction perpendicular to the direction. If this characteristic is utilized, the horizontal viewing angle can be made larger than the vertical viewing angle by causing linearly polarized light whose electric vector oscillates in the horizontal direction to enter the present light distribution control element.

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

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

In the above description, a case has been described in which minute spherical transparent beads are used as the minute lenses. However, the shape of the minute condenser lens is not limited to a sphere such as a hemisphere, a spheroid, a cylinder, or a semicircle, an ellipse, or the like as long as it is a minute body having a light-condensing action. In other words, the light distribution control element of the present invention is composed of a microlens having a light condensing function and a transparent base material supporting the microlens, and the transparent base material arranged on the light emission side is made of an optically isotropic transparent body. With this configuration, different phase differences are prevented from occurring in light traveling at different angles in the transparent base material, and the occurrence of stripe patterns (luminance unevenness) is eliminated.

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 (manufactured by Toyobo Co., Ltd.) using toluene as a solvent is applied to one surface of a transparent substrate 101 made of a flat triacetyl cellulose (TAC) film having a thickness of 80 μm. The transparent adhesive layer 102 was formed by coating with a knife coater so as to have a thickness of 4 μm, dried in a drier, and then cooled to form a solid adhesive layer 102.

Next, a colored adhesive obtained by mixing 10 parts by weight of carbon black with the polyester-based 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 spherical transparent beads 105 made of glass having a refractive index of 1.935 (wavelength: 589.3 nm) and a diameter of 50 μm are dispersed and arranged thereon so as to have a substantially maximum packing density. While maintaining the pressure on the transparent substrate 101 side at 4.5 kg / cm ^2, it is kept in a thermostat at 120 ° C. for 20 minutes. 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 (ne-no) = 0.0001 and (nz-no) = 0.0007, which were optically isotropic transparent films.

When the above light distribution control element was evaluated by inputting unpolarized light, an isotropic and wide viewing angle of about ± 60 ° in both the horizontal and vertical directions (in this case, the luminance becomes 1/2 of the front luminance) Angle) was obtained.

Further, when linearly polarized light was incident, no luminance unevenness causing stripes was observed, and a bright viewing angle characteristic was obtained regardless of the observer's angle.

FIG. 9 is an isoluminance diagram showing light emission characteristics of the light distribution control element of the present embodiment when linearly polarized light is incident, and FIG. 10 is a diagram illustrating horizontal and vertical directions of the light distribution control element of this embodiment when linearly polarized light is incident. The light emission (light distribution) characteristics in the vertical direction are shown.

As shown in FIGS. 9 and 10, the light distribution control element of the present embodiment has a polarization dependence in emission (light distribution) characteristics, and is parallel to the vibration direction of the electric vector of the incident linearly polarized light (horizontal in the drawings). Direction) (± 75 °) is wider than the viewing angle (± 45 °) in a direction perpendicular to the direction. This is for the following reason.

In the present light distribution control element, most of the polarized light incident on the transparent beads 105 is collected while substantially maintaining the polarization state, diffuses, travels through the transparent substrate 101 at various angles, and exits. At this time, since the transparent beads 105 are spherical, the angle of refraction is isotropic regardless of polarization. However, since the p-polarized light and the s-polarized light have different energy transmittances on the surface of the transparent beads 105 and the light emitting side of the transparent substrate 101, the transmission of the p-polarized component to the transparent beads 105 or the surface of the transparent substrate 101. The transmittance was high, and the transmittance of the s-polarized light component was low. As a result, the light distribution characteristics were polarization-dependent.

Accordingly, if circularly polarized light is incident on the present 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 rotation-symmetric microlens such as a spherical transparent bead is used as the microlens as in the present light distribution control element, the light distribution characteristics can be relatively easily changed depending on the polarization state of the incident light.

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

[Example 2 of light distribution control element]
In this example, the light distribution control device shown in FIGS. 1 and 2 was manufactured as follows. After drying a polyester 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). Was applied by a knife coater so as to have a thickness of 4 μm, heated and dried, and then cooled to form a transparent adhesive layer 102 and solidify.

Next, a colored adhesive layer 103 in which 10 parts by weight of carbon black is mixed with a polyester-based hot melt adhesive is formed and solidified in the same manner as described above so that the thickness after drying is 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 embedded 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 58% of the diameter of the transparent beads 105 was exposed. Note that the PC film used for the transparent substrate 101 is an optically isotropic transparent film with (ne-no) ≦ 0.0001 or less. When evaluation was conducted by applying circularly polarized light to the light distribution control element, it was found that 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 to the direction. Characteristics were obtained.

[Example 3 of light distribution control element]
In this example, the light distribution control device shown in FIGS. 1 and 2 was manufactured as follows. A polyester hot melt transparent adhesive dispersed in an aqueous medium is dried on one surface of a transparent base material 101 made of a flat PC film having a thickness of 100 μm and formed into a film by an extrusion method (melt extrusion method) and uniaxially stretched. After applying and drying with a knife coater so that the thickness afterwards becomes 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. After transparent beads 105 are dispersed and arranged on the colored adhesive layer 103, the mixture is held at 120 ° C. for 30 minutes while applying pressure, and the hot melt adhesive layer 104 is formed. Buried in and fixed. The thickness of the hot melt adhesive layer 104 after fixing was about 21 μm, and 58% of the diameter of the transparent beads 105 was exposed.

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

When a linearly polarized light whose vibration direction of the electric vector is parallel or perpendicular to the slow axis of the transparent base material 101 is incident on this light distribution control element, there is no luminance unevenness that causes a stripe pattern. An emission characteristic was obtained in which the viewing angle in a direction parallel to the vector vibration direction was wider than the viewing angle in a direction perpendicular to the direction.

Further, in the present 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-shaped light distribution control element with less curl was obtained.

[Example 4 of light distribution control element]
In this example, the light distribution control device shown in FIGS. 1 and 2 was manufactured 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: Optrez: manufactured by Hitachi Chemical Co., Ltd.) having a thickness of 2 mm formed by injection molding. Was applied by a spin coater so as to have a thickness of 4 μm, dried, and then cooled to form a transparent adhesive layer 102 and solidified.

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

Glass transparent beads 105 having a refractive index of 1.935 (wavelength 589.3 nm) and a diameter of 50 μm are dispersed and arranged thereon, and are held at 120 ° C. for 20 minutes while being pressurized in the same manner as in the above-described embodiment. 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 58% of the diameter of the transparent beads 105 was exposed.

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

{Circle around (4)} When circularly polarized light was incident on this light distribution control element and evaluated, it was found that there was no luminance unevenness causing a stripe 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 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 to this. The emission characteristics were obtained.

Note that the light distribution control element of the present embodiment can be used as a screen of a rear projection display device without a reinforcing member or the like because the transparent base material 101 itself has rigidity.

In the above embodiments, spherical transparent beads were used as the microlenses, but microlenses of other shapes may be used. FIG. 34 is a schematic perspective view showing an example using a microlens of another shape. This uses a columnar transparent micro rod 3401, and is otherwise the same as the previous embodiment.

This light distribution control element has no convergence effect on the incident light in the major axis direction of the minute transparent rod 3401, but has a convergence effect only in a direction orthogonal to the major axis direction. It is said that a wide viewing angle can be obtained. Also in this case, by using a transparent substrate having a small optical anisotropy, it is possible to avoid the occurrence of a stripe pattern when polarized light is incident.

Further, when the light incident on the light distribution control element is linearly polarized light, if the oscillation direction of the polarized light is parallel to the major axis direction of the minute transparent rod, the polarized light is p-polarized with respect to the incident surface of the minute transparent rod. Therefore, the light distribution control element can be used with a high transmittance.

By the way, in each of the above-described embodiments, the microlens is formed of a preformed microparticle such as a transparent bead or a rod, but the light distribution control element of the present invention is not limited to this. That is, a number of minute lenses may be directly formed on a transparent substrate in a two-dimensional array. FIG. 35 is a schematic perspective view showing an example of such a light distribution control element. This light distribution control element is formed by forming microlenses 3502 in a two-dimensional array on an optically substantially isotropic transparent substrate 3501 such as glass, a non-stretched PC film, a TAC film, and an injection molded acrylic resin plate. Further, a black light absorbing layer (black matrix) 3503 having an opening at a light converging portion of the minute lens 3502 is formed.

The light absorption layer 3503 can be formed by a known technique, for example, a printing method, an evaporation method, a photolithography method, or the like. The microlens 3502 is formed by a known technique, for example, pattern exposure of a positive photoresist and development to obtain a columnar three-dimensional shape, and then forming a dome-shaped microlens by surface tension during heating and melting, A transparent resin film which is cured by irradiation with a light beam or an electron beam is formed on a transparent base material 3501, and the light beam or the electron beam is selectively irradiated with the resin film to be cured to remove the uncured portion. .

In any case, by using an optically substantially isotropic transparent body or a transparent body having uniaxial optical anisotropy as the transparent base material 3501, the problem of occurrence of a stripe pattern upon incidence of polarized light is solved. can do.

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

In the projection type display device of the present invention, as shown in FIG. 11, the projection light 704 from the projection device 701 is applied to the transmission type screen 703 via the mirror 702 to display an image. As the mirror 702, a mirror obtained by depositing a reflective metal such as silver or aluminum on optically isotropic transparent glass was used.

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

The light source 801 includes a paraboloid of revolution or a spheroidal reflector and a white light source such as a xenon lamp, a metal halide lamp, or a halogen lamp. Light emitted from the light source 801 is a UV or IR cut filter (not shown) or the like. , The light becomes white light from which ultraviolet rays and infrared rays have been removed, and travels to the color separation dichroic mirror 802.

The 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 transmitted to the liquid crystal display element 809 and the red light (R). Is reflected by total reflection mirrors 805 and 806 and reaches a liquid crystal display element 808. As the liquid crystal display elements 807, 808, and 809, a TN liquid crystal display element can be used.

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

The direction of the long 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 the orientation direction is continuously defined between the transparent glass substrates. It is in a 90 ° twisted state.

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

The polarizer 909 and the analyzer 910 are each formed by applying a triacetyl cellulose (TAC) protective layer on both sides of a film obtained by absorbing iodine into stretched polyvinyl alcohol (PVA) and imparting a polarizing function to each of the transparent glass substrates. It is bonded to the transparent glass substrate 901 and the transparent glass substrate 902 by an acrylic adhesive so as to be optically bonded.

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

Therefore, the respective color lights incident on the liquid crystal display elements 807, 808, and 809 in FIG. 12 are spatially modulated according to the respective image information and emitted. Each color light modulated by each liquid crystal display element passes through polarization state aligning means 812, 813, and 814, which will be described in detail later, enters a color combining cross dichroic prism 811, is combined, 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 the 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 performs the same function as a convex lens, and parallelizes diffused projection light emitted from the projection device 701 to convert the incident angle of light incident on the light distribution control element 100 to 0 degree or its vicinity. Work.

Here, the light distribution control element 100 of the present invention has such a property that the transmittance decreases as the incident angle increases due to its configuration. FIG. 15 is a schematic diagram illustrating a decrease in transmittance due to an increase in the incident angle.

When the incident angle θ of the light is large, the incident light 106 is converged by the transparent beads 105 and is emitted from the transparent substrate 101 while diverging. At this time, the incident angle to the interface between the transparent substrate 101 and air is large. Therefore, the reflection increases and the transmittance remarkably decreases. Further, when the incident angle θ becomes large, the light incident on the transparent beads 101 and converged cannot pass through the opening of the light distribution control element 100, that is, the contact portion between the transparent beads 105 and the transparent adhesive layer 102, and is colored. The light is absorbed by the adhesive layer 103 and its transmittance is reduced.

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

と When the incident angle θ exceeds 10 °, the transmittance sharply 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 be within ± 10 °.

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

Therefore, 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 type, since the incident angles of the respective color lights on the transmission type screen are the same, the above-mentioned reduction in white balance and color shift do not occur.

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

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

That is, the red light (R) and the blue light (B) that have passed through the liquid crystal display elements 807 and 808 are reflected once by the color combining cross dichroic prism 811, so that the vibration directions of the linearly polarized light are the same. Since the green light (G) that has passed through is not reflected at all by the color combining 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 lights.

As described above, the emission characteristics of the light distribution control element 100 of the present invention change depending on the polarization state of the incident light. For this reason, when the light distribution control element of the present invention is used as a transmission screen of a conventional rear projection display device, when viewed from a certain direction, the image shows green, and when viewed from an oblique direction, the image is viewed from an opposite direction. 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 aligning means 812, 813, 814 are arranged on the light emission 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 each color light emitted from the liquid crystal display element is projected on the transmission screen 703.

FIG. 17 is a schematic sectional view showing an example of the polarization state aligning means. This polarization state alignment means includes a transparent substrate 1001 on which a polyimide-based alignment film 1003 is formed, a transparent substrate 1002 on which a polyimide-based alignment film 1004 is 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 periphery is sealed with a sealant 1005 to bond the two transparent substrates to seal the liquid crystal.

FIG. 18 illustrates the operation of the polarization state aligning means. For the sake of simplicity, the directions of the long axes of the liquid crystal molecules near 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 molecule long axis twisted by 45 ° between the two transparent substrates due to the alignment films on the two transparent substrates 1001 and 1002, and is transparent. The liquid crystal alignment direction 1008 on the substrate 1001 side is horizontal 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 on the transparent substrate 910 on the light emission side of the liquid crystal display element, and is parallel to the display surface horizontal direction of the liquid crystal display element. It is inclined at 45 ° to it.

The polarization state aligning means is configured to satisfy the condition of the waveguide for the main wavelength region of the incident light. The conditions of the wave guide are described, for example, in a paper by CH Gooch and HA 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 thickness d of the liquid crystal layer 1006 of the polarization state aligning means and the birefringence Δn at the wavelength λ are set so as to satisfy the expression (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, and 814 may be set so as to satisfy Expression (1) with respect to the main wavelength of the light incident thereon. The main wavelengths of the light incident on 813 and 814 were 450 nm, 650 nn and 550 nm, respectively, and m = 4, so that d · Δn was 626 nm, 903 nm and 765 nm, respectively.

Note that the condition of the wave guide does not change between the extraordinary light mode and the ordinary light mode. Therefore, the alignment direction of the liquid crystal of the polarization state aligning means is 90 degrees with respect to the alignment direction illustrated in FIG. The one rotated by ° 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 is rotated by 45 degrees. The state of polarization 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 with each other.

{Circle around (4)} As in the present embodiment, the following effects can be obtained by setting the vibration direction of the linearly polarized light of each color light to the horizontal direction with respect to the display surface.

Generally, in a single-tube type projection device 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 each two-dimensional optical switch element.

The reflection surface of the dichroic prism or dichroic mirror is formed by a dielectric multilayer film, and the linearly polarized light obliquely incident on this surface is p-polarized light parallel to the incident surface or perpendicular to the incident surface. In the case of light other than s-polarized light, the polarization state changes upon reflection, and generally becomes elliptically polarized light, and the polarization state differs for each color light. However, as described above, if the oscillation direction of the linearly polarized light of each color light is horizontal to the display surface, that is, if it is incident as p-polarized light on the reflection surface of the color combining 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 match.

In other words, 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 due to the polarization dependence of the light distribution characteristics of the light distribution control element 100 used as the transmission screen 703 is performed. 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 projection light is more linearly polarized than the vertical direction due to the polarization dependence of the light distribution characteristics of the light distribution control element 100. The horizontal viewing angle can be widened. This is generally very effective in efficiently distributing limited light to an observer because a display device generally requires a wider viewing angle in the horizontal direction than in the vertical direction.

The rear-projection display device having the above configuration is used as the light distribution control element 100 of the transmission screen 703, and the light distribution control element 100 illustrated in [Example 1 of the light distribution control element] has a thickness on the transparent substrate 101 side. When evaluated using a 2 mm flat and transparent optically isotropic acrylic plate bonded together, a horizontal viewing angle of ± 75 ° and a vertical viewing angle of ± 45 °, a wide viewing angle in both directions was gotten. Furthermore, when viewed from an oblique direction, no stripe pattern or coloring occurred.

Unnecessary light entering the transmissive screen from the outside is absorbed by the colored adhesive layer 103 of the light distribution control element 100, and thus has a low luminance of 0.5 cd / m ² in a bright environment (vertical illuminance: 300 lx). Black display was realized.

In addition, the polarization state alignment means of the rear projection type display device of the present invention may be any 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.

高分子 The polymer laminated film having a twist structure used as the polarization state aligning means is realized by, for example, laminating four PC film retardation films having a retardation d · Δn = 275 nm. In the four retardation films, the slow axes of the respective retardation films from the side closer to the liquid crystal display element are 5.6 °, 16.9 °, 28 .1 ° and 39.4 °. In this case, the same effect as in the above embodiment can be obtained.

When a half-wave plate is used as the polarization state aligning means, the slow axis of the wave plate functioning as a half-wave plate with respect to the wavelength of light passing through each liquid crystal display element is detected. By arranging the photons at an angle of 22.5 ° with respect to the transmission axis of the photons, the same effect as in the above embodiment can be obtained.

Further, a half-wave plate is disposed as a polarization state aligning means only on the light emission side of the liquid crystal display element in which the oscillation direction of the emitted linearly polarized light is different from that of the other liquid crystal display elements. Even if it is made to match, it is possible to prevent coloring to some extent when obliquely observed.

In the above 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. By using a liquid crystal display element configured to be in the horizontal direction or the vertical direction with respect to the liquid crystal display element, it is possible to provide the function of the polarization state aligning means to 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 even after the color synthesis, it is the same as in the above embodiment without disposing another optical element on the light emission side of the liquid crystal display element. An effect can be obtained.

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

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

In addition, in the present invention, by using a single tube 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, it is possible to eliminate the coloring that occurs when obliquely observed due to the polarization dependence of the light distribution characteristics of the light distribution control element 100. is there. Further, the light distribution control element 100 of the present invention used as the transmission 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 a rear-projection display device which can obtain a high contrast ratio by realizing low-luminance black display even in a bright environment can be realized.

In the rear projection display device described above, the case where a plurality of two-dimensional optical switch elements are used for the projection device has been described. However, a so-called single-plate type projection device using only one two-dimensional optical switch element is used. Is 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 unambiguously determined without being aligned, so that the light distribution characteristic of the light distribution control element 100 of the present invention is colored by the polarization dependence. Does not occur.

[Example 2 of rear projection type display device]
Next, another rear projection display device of the present invention will be described. The rear projection display device described here has 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 passes through the mirror 702. Although the image is displayed by irradiating the transmission type screen 703 with the light, the configuration of the projection device 701 is partially different.

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

In the present projection apparatus, similarly to the above-described 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 color separation dichroic mirrors 802 and 803. The light enters the liquid crystal display elements 807, 809, and 808 via 804, 805, and 806, respectively. The light incident on the liquid crystal display element is spatially modulated in accordance with the image information of each color and emitted, and the polarization state aligning means 812, 813, and 814 convert each color light into linearly polarized light having the same vibration direction. The light enters the dichroic prism 811.

At this time, it is desirable that each color light incident on the color combining cross dichroic prism 811 be 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 formed of a dielectric multilayer film, and unless specially designed and formed, linearly polarized light obliquely incident on the mirror surface is parallel to the incident surface. This is because if the light is not polarized light or s-polarized light perpendicular to the plane of incidence, the polarization state changes upon reflection, and generally becomes elliptically polarized light, and the polarization state of each color light is different.

Here, an example in which the image light enters the prism 811 as p-polarized light with respect to the mirror surface of the color combining 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 enters the color combining dichroic prism 811 and undergoes color combining is projected on 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 image light after color synthesis, and 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 on which a transparent electrode 1103 made of ITO and an alignment film 1104 made of a polyimide-based polymer are entirely laminated. A gap is formed by sandwiching a spacer (not shown) between the second transparent glass substrate 1102 on which the film 1106 is entirely formed and the two transparent glass substrates 1101 and 1102, and the periphery thereof is sealed with a sealant 1108. The liquid crystal layer 1107 made of a nematic liquid crystal having a positive dielectric anisotropy enclosed in the space formed by the above operation.

The long axis of the liquid crystal molecules of the liquid crystal layer 1107 is continuously rotated by 90 ° between the two transparent glass substrates 1101 and 1102 by performing an alignment process such as a rubbing process on the alignment films 1104 and 1106 formed on the two substrates. 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. FIGS. 21 and 22 are schematic diagrams illustrating the operation of the polarization state conversion element 815. Arrows indicated by reference numerals 1110 and 1111 indicate the alignment directions of the liquid crystal on the transparent glass substrates 1101 and 1102, respectively.

The orientation direction 1111 of the liquid crystal on the transparent glass substrate 1102 on the light incident side 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 condition of the waveguide in the visible wavelength region. Things.

Accordingly, 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 optical image light incident on the polarization state conversion element 815 rotates its electric vector oscillation direction by 90 °. Is converted into linearly polarized light having a vibration direction perpendicular to the display surface, and is projected on the transmission screen 703 via the projection lens 810.

透過 The transmission screen 703 used in the rear projection display device is composed of a light distribution control element using spherical transparent beads as micro lenses and a Fresnel lens, as in the above-described embodiment.

In this case, as described above, if the projection light incident on the transmissive screen 703 is a 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 dependence. The viewing angle in the vertical direction becomes wider than in the horizontal direction.

As illustrated in FIG. 22, a voltage is applied to the transparent electrode 1103 and the transparent electrode 1105 formed on two transparent glass substrates, and an electric field is applied to the liquid crystal layer 1107, so that the liquid crystal molecules have a molecular length. When the axis is set to be substantially perpendicular to the transparent glass substrate, the optical image light incident on the polarization state conversion element 815 passes through with almost no change in the polarization state. That is, the light is projected onto the transmission screen 703 via 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 is 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 transmission screen 703.

That is, in the conventional rear projection display device, the viewing angle characteristics could not be changed without replacing the transmissive screen. However, in the rear projection display device of the present invention, the voltage applied to the liquid crystal layer of the polarization state conversion element 815 was changed. There is an epoch-making effect that the viewing angle characteristics can be easily changed by a simple operation of controlling the applied 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, the only difference from the TN liquid crystal element is a 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. Therefore, a description will be given with reference to a schematic cross-sectional view of the TN liquid crystal element illustrated in FIG.

The polarization state conversion element 815 composed of an ECB liquid crystal element has a transparent electrode 1103 composed of ITO and an alignment film 1104 composed of a polyimide-based polymer, like the polarization state conversion element 815 composed of the TN liquid crystal element. A first transparent glass substrate 1101 having a laminated structure, a second transparent glass substrate 1102 also having a transparent electrode 1105 and an alignment film 1106 formed over the entire surface, and a spacer (not shown) are provided between the two transparent glass substrates. A liquid crystal layer 1107 made of nematic liquid crystal sealed in a space formed by forming a gap by sandwiching and connecting the periphery with a sealant 1108.

The nematic liquid crystal may have a positive or negative dielectric anisotropy, but the liquid crystal orientation is a homogeneous alignment for a nematic liquid crystal having a positive dielectric anisotropy, and a nematic liquid crystal having a negative dielectric anisotropy. In the case of liquid crystal, homeotropic alignment is used.

At this time, in order to make the alignment direction of the liquid crystal when an electric field is applied to the liquid crystal layer 1107 uniform, a pretilt angle of about 1 to 4 ° is provided in each case, and the direction of the molecular long axis of the liquid crystal is set to 45 ° with respect to the display surface. The alignment process is performed so as to be in the direction of °.

場合 When the thickness of the liquid crystal layer 1107 is d and the anisotropy of the refractive index 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 thus configured, by applying a voltage to the transparent electrodes 1103 and 1105 formed on two transparent glass substrates and applying an electric field to the liquid crystal layer 1107, the incident optical image light In contrast, the apparent d · Δn of the liquid crystal layer 1107 can be controlled in the range of 0 to λ / 2.

Therefore, 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 without substantially changing the polarization state. Incident on the transmissive screen 703 as linearly polarized light having the vibration direction of. In this case, the viewing angle in the horizontal direction is 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 transmission screen 703.

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 electric vector is rotated by 90 °, that is, with respect to the display surface. As a result, the light is converted into linearly polarized light having a vertical vibration direction and is incident on the transmission screen 703. 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.

{Circle around (4)} When the apparent d · Δn of the liquid crystal layer is λ / 4, the image light incident on the polarization conversion element 815 becomes substantially circularly polarized light and is incident on the transmission screen 703. In this case, the same isotropic viewing angle can be obtained in both the vertical and horizontal directions.

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.

ネ Nematic liquid crystal having dielectric anisotropy Δε = −4.2 and 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 3.5 μm. As the alignment films 1104 and 1105, rubbing treatment was performed in a direction forming an angle of 45 ° with respect to the horizontal direction of the display surface, and a pretilt of about 2 ° was applied to the liquid crystal molecules, using a polyimide alignment film exhibiting vertical alignment.

In the liquid crystal layer 1107 of this polarization state conversion element 815, when no electric field is applied, the apparent dΔn of the liquid crystal layer 1107 is almost 0. Therefore, as shown in FIG. The light passes through the projection screen 810 and is projected onto the transmission screen 703 via the projection lens 810 in a state of linearly polarized light having a vibration direction in a horizontal direction with respect to the display surface. In this case, the viewing angle in the horizontal direction is 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 transmission screen 703.

On the other hand, as shown in FIG. 24, by applying a voltage to the transparent electrodes formed on the two transparent glass substrates and applying an electric field to the liquid crystal layer 1107, the molecular major axis of the liquid crystal molecules is moved relative to the transparent glass substrate. When the liquid crystal layer 1107 is tilted 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 approximately 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 substantially perpendicular to the display surface. 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 constituting the transmission screen 703.

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

That is, in the conventional rear projection display device, the viewing angle characteristics could not be changed without replacing the transmissive screen, but in the present rear projection display device, a TN liquid crystal element or an ECB liquid crystal element was used. By controlling the electric field applied to the liquid crystal layer of the polarized 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 equally isotropic. The viewing angle characteristics can be easily changed such that a proper viewing angle is 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. In addition, for example, a phase difference plate may be provided as the polarization state conversion element 815. Thus, a desired viewing angle characteristic may be obtained. For example, various modifications such as disposing a quarter-wave 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.

[Third Embodiment of Rear Projection Display Device]
Next, another rear projection display device of the present invention will be described. FIG. 40 is a schematic structural perspective view of the rear projection display device of the present embodiment.

The rear projection type display apparatus of the present embodiment is different from the rear projection type display apparatus of the second embodiment in that an observer sensing unit 4002 for sensing the presence or absence of an observer and a sensing signal from the observer sensing unit are received for observation. Observer position determining means (not shown) for determining the horizontal and vertical positions of the observer, and control signal output means (not shown) for outputting a control signal to a polarization state conversion element arranged in the projection device 701 based on the information. Is added.

The observer sensing unit 4002 includes a plurality of observer sensing sensors, and each of the observer sensing sensors senses an observer present in a plurality of divided areas. An infrared sensor is used as the observer detection sensor.

FIGS. 41 and 42 show examples of the divided areas detected by the observer sensor. FIG. 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 sensing sensors for sensing the observer 4100 are required.

The nine observer sensing sensors provided in the observer sensing unit 4002 respectively sense the observer 4100 observing in front of the rear projection display device 4001, and the observer position determining means is vertically determined based on each sensed signal. Then, it is determined in which horizontal area (position) the observer 4100 exists. The control signal output means outputs a control signal to the polarization conversion element of the projection device 701 based on the information of the observer position determination means.

Here, similarly to the second embodiment, the rear-projection display device of the present embodiment changes the polarization state of the projection light 704 by using a polarization state conversion element in the projection device 701 to thereby change the viewing angle of the transmission screen 703. Characteristics can be changed. In other words, a bright image can be provided to the observer by sensing and determining 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 effects of the rear projection display device will be described with reference to FIGS. 43 and 44. In general, in a rear projection display device, in order to effectively distribute limited light toward a viewer, a vertical viewing angle is set to be narrower than a horizontal viewing angle, as shown in FIG. 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. Therefore, unless the observer 4100 observes at an appropriate height by sitting in a chair or the like, or observes at a certain distance, good image quality cannot be obtained.

Therefore, as illustrated in FIG. 43, even if the observer 4100 can view a good image when sitting in a chair, when the user stands up, the image under the screen 703 becomes dark, and the good image cannot be viewed. There was the problem.

However, in the case of the rear projection type 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. You. Further, the control signal output means controls the polarization state conversion element based on the observer's position information, and converts the polarization state of the projection light into an appropriate state, as shown in FIG. A good image can be provided to the observer 4102 who stands up by expanding the 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 light is projected in the horizontal direction rather than in the vertical direction. Has a wide viewing angle characteristic.

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 projected light has a vibration direction perpendicular to the display surface of the screen 703. By converting the light into linearly polarized light, a favorable image can be provided to the observer 4102 by widening the vertical viewing angle as illustrated in FIG.

As described above, in the rear projection type display device, the viewing angle characteristic automatically changes according to the position of the observer, and the limited image light can be effectively distributed to the observer, so that the observer is optional. A good image can be obtained at the position.

[Fourth Embodiment of Rear Projection Display Device]
Next, another rear projection type display device of the present invention will be described. The rear projection display device of the present embodiment is the same as the embodiment described with reference to FIG. 11, but the configuration of the two-dimensional optical switch element used for the projection device 701 is different.

The feature of the rear projection type display device is that the two-dimensional optical switch element used in the projection device 701 performs display in a non-polarized state without using polarized light for display. It is possible to fundamentally avoid problems such as generation of a striped pattern due to optical anisotropy of the transparent base material of the light distribution control element 100 and chromaticity change due to polarization dependence of the light distribution characteristic 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. Here, first, the 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 in microcapsules dispersed in a polymer, liquid crystal droplets dispersed in a polymer matrix, or a network-like liquid crystal continuous layer. There are those formed with a polymer.

FIG. 25 is a schematic cross-sectional view showing an example of the polymer dispersion type liquid crystal element. The polymer-dispersed liquid crystal element 2500 includes a first transparent glass substrate 2501 on which a transparent electrode 2503 made of ITO is formed on the entire surface, a transparent electrode 2504 for forming a pixel, and a wiring and a thin film transistor (not shown) connected thereto. It comprises a second transparent glass substrate 2502 having switching elements 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 formed by dispersing liquid crystal droplets 2506 having a positive dielectric anisotropy in a polymer 2507 such as polyvinyl alcohol, and the refractive index of the liquid crystal in the minor axis direction 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 of the polymer dispersed liquid crystal layer 2505 are irregularly arranged due to the effects 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 major axis direction of the liquid crystal molecules to the refractive index no in the minor axis direction of the liquid crystal are floating in the polymer matrix having the refractive index no. The incident light is refracted and scattered at interfaces having different refractive indexes.

On the other hand, when an electric field is applied to the liquid crystal by applying a voltage to the transparent electrodes on the transparent glass substrates 2501 and 2502, the liquid crystal is arranged with its molecular long axis perpendicular to the transparent glass substrate and viewed from the light traveling direction. The refractive index of the liquid crystal becomes constant at no and matches 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.

As described above, in the polymer dispersed liquid crystal element, the degree of light scattering can be changed by applying / non-applying an electric field to the polymer dispersed liquid crystal layer 2505. However, since the amount of transmitted light does not change, an optical system that converts the degree of scattering of light into light and dark of light is required in order to use it for display. As is well known, a Schlieren optical system is used for such a purpose.

FIGS. 27 and 28 are schematic diagrams illustrating the display operation of a polymer dispersed liquid crystal element using a schlieren optical system. Substantially parallel light emitted from the light source 2801 is converged on the opening of the entrance-side stop 2803 by the action of the converging lens 2802, and light that has passed through the opening of the entrance-side stop 2803 becomes almost parallel light again by the lens 2701 and becomes a polymer dispersion type. The light enters the liquid crystal element 2500. As shown in the figure, when a sufficient electric field is applied to the polymer dispersed liquid crystal element 2500 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 converged by the converging lens 2702. The light is converged and passes through the opening of the exit-side stop 2817.

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

Next, a description will be given of a projection apparatus using a polymer dispersed liquid crystal element as a two-dimensional optical switch element.

FIG. 29 is a schematic sectional view showing an example of a projection device using a polymer dispersed liquid crystal element.

The light source 2801 is composed of a reflector having a paraboloid of revolution and a metal halide lamp having a light-emitting portion arranged at the focal point of the reflector. Most of the light emitted from the light-emitting portion is reflected by the reflector and becomes substantially parallel light. I do. Light emitted from the light source 2801 passes through a UV / IR cut filter (not shown) to become white light from which ultraviolet rays and infrared rays have been removed. Converged.

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

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 and is incident on the incident side lens 2811, and is converted into parallel light by the action of the polymer dispersed liquid crystal. Light enters the element 2814.

The blue light transmitted through the green light reflecting dichroic mirror 2805 is incident on the incident side lens 2810, becomes parallel light by the action thereof, and is incident on the polymer dispersed liquid crystal element 2813.

色 Each color light incident on the polymer dispersion type liquid crystal elements 2813, 2814, 2815 is emitted from the polymer dispersion type liquid crystal element with the scattering state controlled according to the respective image information. The red light that has passed through the polymer dispersed 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.

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

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

の 後 The rear group lens 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 entrance side stop 2803. For this reason, of the light incident on the projection lens 2819, the light of the pixel which has not been scattered by the polymer dispersion type liquid crystal elements 2813, 2814, 2815 passes through the exit side stop 2817 and is displayed brightly.

On the other hand, some or most of the light of the pixels that have been scattered by the polymer dispersion type liquid crystal elements 2813, 2814, and 2815 cannot pass through the exit-side aperture 2817, resulting in dark display.

(4) The optical image light projected from the projection apparatus in this way 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 transmission screen 703 is non-polarized light, even if the transparent base of the light distribution control element 100 constituting the optical screen has birefringence, the optical anisotropy of the transparent base is obtained. Problems such as the occurrence of a stripe pattern due to the nature and the change in chromaticity due to the polarization dependence of the light distribution characteristics 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.

As described above, instead of a film having a small birefringence, for example, an expensive and weak film such as a TAC film, an inexpensive and high-strength film such as a biaxially stretched PET film is used as a member of the 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. The biaxially stretched film has increased tensile strength and impact strength as compared with a non-stretched film, and also has significantly improved physical properties such as transparency and operating temperature range.

The light distribution control element 100 was manufactured by the method described below. On the surface of the transparent base material 101, a transparent adhesive layer made of a polyester-based hot-melt adhesive was 5 μm, and on top of that, a colored adhesive layer obtained by mixing 10 parts by weight of carbon black with the polyester-based hot-melt adhesive was 4.5 μm. Form and once solidify.

Spherical transparent glass beads having a refractive index of 1.935 (wavelength: 589.3 nm) and a diameter of 50 μm are densely dispersed thereon, and the transparent adhesive layer and the colored adhesive layer are softened in a thermostat. Meanwhile, the transparent beads are pressed against the transparent base material side by a pressure plate to bury and fix the beads in the adhesive layer. The thickness of the adhesive layer after fixing the transparent beads was about 21 μm in total for 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 flat, 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 side of the transparent substrate 101, and a Fresnel lens is disposed on the side of the transparent beads 105 to form a transmission screen. A rear projection type display device as shown in FIG. 11 was realized by combining the device 703 with a projection device 701 and a mirror 702 using a polymer dispersed liquid crystal device as a two-dimensional optical switch device.

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 polarization state of the light distribution characteristics of the light distribution control element 100 constituting the transmission type screen 703 was determined. A high-quality image without coloring or stripes due to dependence was obtained. Further, both the horizontal direction and the vertical direction were as wide as ± 60 °, and an isotropic viewing angle was obtained.

Further, unnecessary light entering the transmissive screen from the outside is absorbed by the colored adhesive layer of the light distribution control element, and therefore, in a bright environment (vertical illuminance: 300 lx), the black light having a low luminance of 0.5 cd / m ^2. Display was realized, and a high contrast ratio was obtained even in a bright environment.

Incidentally, as a two-dimensional optical switch element which does not use polarized light for display, a digital mirror described in U.S. Pat. Nos. 5,610,049 and 5,083,857 or U.S. Patent Application No. 08/161832 and U.S. Pat. A device (DMD) can be used.

The DMD has an array of micromirrors corresponding to pixels supported by a torsion hinge on a semiconductor substrate, and an address electrode. When a voltage is applied to the address electrodes, the micromirrors exert an electrostatic attraction force. Deflecting or rotating.

Therefore, 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 the display can be performed with no polarization, the transparent base material of the light distribution control element used as the transmission screen is optically anisotropic, as in the rear projection display apparatus using the polymer dispersed liquid crystal element. Even with this, it is possible to obtain a high-quality image without coloring or stripes due to the polarization dependence of the light distribution characteristics.

[Fifth Embodiment 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 has a projection device 701, a mirror 702, and a transmission type 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 passes through the mirror 702. Although the image is displayed by irradiating the transmission screen 703 via the transmission screen 703, the configuration of the projection device 701 is different.

One of the points of the present invention is that the image light incident on the light distribution control element 100 constituting the transmissive screen 703 is substantially non-polarized light. Therefore, in this embodiment, in addition to using a display element capable of displaying non-polarized light as the two-dimensional optical switch element, a depolarizing means for depolarizing light is disposed between the light distribution control element and the two-dimensional optical switch element. To achieve this.

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

As the depolarizer, for example, a quartz plate having a refractive index anisotropy Δn = 0.009 and a thickness of 2 mm and a thickness of 1 mm, which is cut out and polished in parallel with the optical axis, and whose slow axes are at 45 ° to each other. Lyot depolarizers can be used. If this depolarizer is used, it becomes a nearly perfect depolarizer for white light. Also, when the film thickness is d and the refractive index anisotropy is Δn, a polymer liquid crystal film or a retardation film in which d · Δn is sufficiently large with respect to a visible wavelength is laminated, and a pseudo depolarizer is similarly formed. May be.

擬 似 Such a pseudo depolarizer may be arranged in the optical path after the light that has passed through the two-dimensional optical switch elements 807, 808, and 809 has been color-combined, for example, as in the projection device shown in FIG. FIG. 30 shows a projection device using the TN liquid crystal display element described in the above embodiment, in which a pseudo depolarizer 3000 is newly arranged. Thus, the optical image light whose polarization has been substantially eliminated can be projected on the transmission 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 characteristics of the light distribution control element 100 and the high quality without stripes are obtained. Images can be obtained. Further, 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. Becomes possible. In the rear projection display device described above, a description has been given of a case where a transmission type liquid crystal display device is used as the two-dimensional optical switch element of the projection device. However, the present invention is not limited to this, and a reflection type display device may be used. There may be.

Further, 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, and 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 sectional view of a direct-view type 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 and front surfaces of the liquid crystal display element 1302, respectively. The light distribution control device 100 of the present invention is provided on the front surface of the photon 1214.

The backlight device 1301 is capable of efficiently emitting substantially parallel light, and is described in, for example, Japanese Patent Publication No. 9-505412 and International Publication No. WO95 / 14255, “Backlight assembly for electro-optical display”. ] Can be used.

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

As the light collimating means 1203, a known element, for example, a quadrangular pyramid-shaped micro taper 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 at least once on the wall surface of the micro-tapered rod, and is emitted after being made substantially parallel.

マ イ ク ロ Alternatively, as the light collimating means 1203, a micro prism sheet or a micro lens 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 of ± 10 ° or less 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 a polyimide polymer, an alignment film 1207, a transparent electrode 1206 forming a pixel, and a connection therewith. The dielectric anisotropy sealed between a second transparent substrate 1205 having a wiring and a switching element such as a thin film transistor (not shown) and two transparent substrates 1212 and 1210 connected via a sealant 1208 is positive. And a liquid crystal layer 1209 made of a nematic liquid crystal.

The liquid crystal display element 1302 performs rubbing treatment on the alignment films 1207 and 1211 applied to the two transparent substrates 1205 and 1210 so that the long axis of the liquid crystal molecules of the liquid crystal layer 1209 is continuously provided between the two transparent substrates. It constitutes a so-called TN liquid crystal display element twisted by 90 °.

偏光 A polarizer 1204 and an analyzer 1214 are disposed on the light incident surface and the light exit surface of the liquid crystal display element 1302, respectively, so as to transmit linearly polarized light orthogonal to each other. As the polarizer 1204 and the analyzer 1214, those obtained by applying a TAC protective layer to both surfaces of a film obtained by absorbing iodine into stretched PVA and imparting a polarizing function are used, and an acrylic-based material is used for the transparent substrate 1205 and the transparent substrate 1210, respectively. An adhesive is used to bond optically.

光 The light distribution control element 100 is disposed in front of the analyzer 1214. As the light distribution control element 100, the element described in the first embodiment of the light distribution control element was used. Here, the bonding with the analyzer 1214 was performed by the adhesive 1213 patterned so as to surround the display section of the liquid crystal display element. However, the gap between the transparent beads of the light distribution control element 100 and the analyzer 1214 was formed. May be bonded so as to be filled with a transparent adhesive having a low refractive index, or a combination of these may be used.

Next, the operation of the direct-view type liquid crystal display device will be described. Of the light 1215 emitted from the backlight device 1301, linearly polarized light transmitted through the polarizer 1204 is transmitted through the liquid crystal panel 1302 and is incident on the analyzer 1214. At this time, the polarization state of light transmitted through the liquid crystal panel 1302 changes depending on the electric field applied to the liquid crystal layer 1209, so that the electric field corresponding to the image information is applied to the liquid crystal layer 1209 to transmit the light through 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 converges and diverges due to the refraction.

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

{Circle around (4)} As described above, the transmittance of the light distribution control element 100 decreases as the incident angle of the incident light increases, due to absorption by the colored adhesive layer. Therefore, of 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 tone change is absorbed by the colored adhesive layer.

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

Further, in the present liquid crystal display device, since the light emitted from the backlight device 1301 to the liquid crystal display element 1302 is substantially parallel light, if the light amount ratio in the angle range where 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 a high-brightness and high-contrast image can be obtained. Further, since the light distribution control element 100 has a high effect of reducing stray light due to unnecessary external light, a black display with low luminance is realized even in a bright environment, and an image with a high contrast ratio is obtained.

と こ ろ When the liquid crystal display device having the above configuration was evaluated, there was no color tone change or gradation inversion within a viewing angle range of ± 80 °, and an isotropic and wide viewing angle having a contrast ratio of 100: 1 or more was obtained.

Normally, in the TN liquid crystal display device, the transmission axes of the linearly polarized light of the polarizer and the analyzer form an angle of 45 ° with respect to the horizontal direction of the display surface in order to ensure the horizontal symmetry of the contrast ratio. 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 near a viewing angle of 0 ° at which good image quality is obtained, and thus the polarizer 1204 and the analyzer 1214 are obtained. The symmetry of the contrast ratio can be maintained without setting the linearly polarized light transmission axis at 45 ° or 135 ° with respect to the horizontal direction of the display surface. Rather, due to the polarization dependence of the light distribution characteristics of the light distribution control element constituting the present liquid crystal display device, 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. Should be.

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 aligned with the liquid crystal display device. Arrange horizontally with respect to the display surface. Therefore, the orientation direction of the liquid crystal is learned from this, and the orientation direction of the liquid crystal on the transparent substrate 1205 side is perpendicular 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 the orientation direction of the liquid crystal display device. Or the liquid crystal orientation direction on the transparent substrate 1205 side is horizontal to the liquid crystal display device display surface, and the liquid crystal orientation direction on the transparent substrate 1210 side is vertical to the liquid crystal display device display surface. And

構成 With the above configuration, 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, as described above, due to the polarization dependence of the light distribution characteristics of the light distribution control element 100, a liquid crystal display element having a wider viewing angle in the horizontal direction than in the vertical direction on the display surface and symmetric brightness can be obtained. . This is very effective in efficiently distributing limited light to an 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 sectional view of another direct-view type liquid crystal display device of the present invention. This liquid crystal display device is the same as the liquid crystal display device shown in FIG. 31, except that a retardation plate 3100 is arranged between the analyzer 1214 and the light distribution control element 100.

と お り As described above, the light distribution control element 100 of the present liquid crystal display device has its light distribution characteristics, that is, the viewing angle, changed depending on the polarization state of the incident light. The retardation plate 3100 has a function of utilizing this property to convert linearly polarized light transmitted through the analyzer 1214 into polarized light having a desired viewing angle.

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

Further, in order to obtain the 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 retardation plate 3100, for example, a half-wave plate is disposed with its slow axis inclined at 22.5 ° with respect to the transmission axis of the analyzer, and the light incident on the light distribution control element 100 is linearly shifted. The polarization direction may be changed so that the oscillation direction of the polarization is horizontal to the display surface.

In this case, 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 symmetric brightness is obtained by simply adding the retardation 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 a horizontal direction than in a vertical direction, which is very effective in efficiently distributing limited light to a viewer.

The same effect can be obtained by disposing a polymer laminated film having a twisted structure instead of the retardation plate 3100. Such a polymer laminated film is realized by, for example, laminating four retardation films of a PC film having retardation d · Δn = 275 nm, and the four retardation films are retarded from the one closer to the 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-described embodiment, an example of a TN liquid crystal panel for monochrome display has been described as a liquid crystal display element in order to make the drawings easy to see, but a liquid crystal display element for full color display in which a transparent substrate is provided with a micro color filter may be used. Needless to say.

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

It is a schematic cross section of a light distribution control element of the present invention. It is a schematic 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 the present invention. FIG. 7 is an isoluminance diagram showing light emission (light distribution) characteristics of a conventional light distribution control element when polarized light is incident. It is explanatory drawing of the coordinate system of an isoluminance diagram. It is explanatory drawing of the circular tangent cross section of a refractive index ellipsoid. It is an explanatory view of an optical axis of a polyethylene terephthalate film. 4 is a graph showing a relationship between a light incident angle and an energy transmittance of a polyethylene terephthalate film. FIG. 4 is an isoluminance diagram showing light emission characteristics of the light distribution control element of the present invention when linearly polarized light is incident. 5 is a graph showing light emission (light distribution) characteristics of the light distribution control element of the present invention when linearly polarized light is incident. FIG. 1 is a schematic sectional view of a rear projection display device of the present invention. FIG. 1 is a schematic sectional view of a projection device according to a rear projection display device of the present invention. FIG. 3 is a schematic cross-sectional view of a two-dimensional optical switch of the projection device according to the rear projection display device of the present invention. FIG. 1 is a schematic cross-sectional view of a transmission screen according to a rear projection display device of the present invention. FIG. 3 is a schematic diagram for describing the dependence of the transmittance of the light distribution control element of the present invention on the light incident angle. 5 is a graph showing an example of the relationship between the transmittance and the light incident angle of the light distribution control element of the present invention. FIG. 3 is a schematic cross-sectional view of a polarization state aligning unit used in the projection device according to the rear projection display device of the present invention. FIG. 4 is a schematic diagram for explaining the operation of a polarization state alignment unit used in the projection device according to the rear projection display device of the present invention. FIG. 1 is a schematic sectional view of a projection device according to a rear projection display device of the present invention. FIG. 3 is a schematic cross-sectional view of a polarization state conversion element used for a projection device according to the rear projection display device of the present invention. It is a schematic diagram for explaining the operation of the polarization state conversion element used in the projection device according to the rear projection type display device of the present invention. It is a schematic diagram for explaining the operation of the polarization state conversion element used in the projection device according to the rear projection type display device of the present invention. It is a schematic diagram for explaining the operation of the polarization state conversion element used in the projection device according to the rear projection type display device of the present invention. It is a schematic diagram for explaining the operation of the polarization state conversion element used in the projection device according to the rear projection type display device of the present invention. FIG. 2 is a schematic sectional view of a polymer dispersion type liquid crystal display element of the projection device according to the rear projection type display device of the present invention. FIG. 4 is a schematic diagram for explaining the operation of the polymer dispersion type liquid crystal display element. FIG. 2 is a schematic diagram for explaining an optical system for performing display by a polymer dispersion type liquid crystal display element. FIG. 2 is a schematic diagram for explaining an optical system for performing display by a polymer dispersion type liquid crystal display element. FIG. 1 is a schematic sectional view of a projection device according to a rear projection display device of the present invention. FIG. 1 is a schematic sectional view of a projection device according to a rear projection display device of the present invention. It is a schematic cross section of the liquid crystal display of the present invention. FIG. 3 is a schematic diagram for explaining a linearly polarized light transmission axis of a polarizer and an analyzer of the liquid crystal display device of the present invention. It is a schematic cross section of the liquid crystal display of the present invention. It is a schematic perspective view of the light distribution control element of this invention. It is a schematic perspective view of the light distribution control element of this invention. It is a schematic cross section which shows an example of a lenticular lens sheet. It is a schematic perspective view which shows an example of a lenticular lens sheet. It is a schematic cross section which shows an example of the conventional transmission screen. It is a perspective view of the conventional transmission screen. FIG. 1 is a schematic perspective view of a rear projection display device of the present invention. FIG. 4 is an explanatory diagram illustrating a divided area sensed by an observer sensing unit of the rear projection display device of the present invention. FIG. 4 is an explanatory diagram illustrating a divided area sensed by an observer sensing unit of the rear projection display device of the present invention. It is a figure for explaining an effect of a rear projection type display of the present invention. It is a figure for explaining an effect of a rear projection type display of the present invention.

Explanation of reference numerals

Reference Signs List 100 light distribution control element, 101 transparent substrate, 102 transparent adhesive layer, 103 colored adhesive layer, 104 adhesive layer, 105 transparent beads, 106 incident light, 107 unnecessary (external) light 701: Projection device, 702: Mirror, 703: Transmission 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 synthesizing 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: sealant, 909: polarizer, 910: analyzer, 801f: Fresnel lens, 3401: fine Transparent rod, 1001, 1002 transparent substrate, 1301 backlight device, 1302 liquid crystal display element, 1003, 1004 alignment film, 1005 sealant, 1006 liquid crystal layer, 911, 912, 1007, 1008 liquid crystal alignment direction , 1201 ... light source, 1202 ... light guide, 1203 ... light collimating means, 1204 ... polarizer, 1214 ... analyzer, 1215 ... outgoing light, 2501,250 ... 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 ... stop, 2813, 2814, 2815: polymer dispersed liquid crystal element, 2819 ... Projection lens, 3501 ... Transparent substrate, 3502 ... Micro lens, 35 3 ... light absorption layer, 3100 ... retardation plate, 4001 ... rear projection display, 4002 ... observer sensing unit, 4100 ... observer, 3000 ... pseudo depolarizer.

Claims (6)

In a projection display device having a projection device that projects an optical image and a transmission screen,
The projection device has a light source, a plurality of two-dimensional optical switch elements that modulate light from the light source into an optical image according to image information, and a projection lens that projects the optical image onto the transmission screen,
The two-dimensional optical switch element is a two-dimensional optical switch element that forms an optical image using polarized light,
When the light of the optical image is incident on a transmission screen, the polarization state thereof is substantially matched in a visible wavelength range. In a projection display device having a projection device that projects an optical image and a transmission screen,
The projection device has a light source, a plurality of two-dimensional optical switch elements that modulate light from the light source into an optical image according to image information, and a projection lens that projects the optical image onto the transmission screen,
The two-dimensional optical switch element is a two-dimensional optical switch element that forms an optical image using polarized light,
A projection-type display device, comprising: a polarization state aligning unit that approximately matches the polarization state of the optical image light between the two-dimensional optical switch element and the transmission screen. 3. The projection display device according to claim 2, wherein the polarization state aligning means is an optical element having a liquid crystal layer that satisfies a condition of a waveguide arranged on a light emission side of the two-dimensional optical switch element. 3. The projection display device according to claim 2, wherein the polarization state aligning means is a half-wave plate or a laminate of a polymer film disposed on the light emission side of the two-dimensional optical switch element. The two-dimensional optical switch element has a liquid crystal display element and an analyzer,
2. The projection display device according to claim 1, wherein transmission axes of linearly polarized light of the analyzer substantially coincide with each other with respect to a display surface. The projection display device according to claim 5, wherein a transmission axis of the linearly polarized light of the analyzer is in a horizontal direction or a vertical direction with respect to a display surface.

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