JP2014059432A - Image display system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image display system capable of displaying a high quality image by suppressing the dispersion of a video light incident on a polymer dispersion type liquid crystal layer from a front surface side.SOLUTION: An image display system 100 has a screen 200 and a light projection device 900. The screen 200 includes: an alignment layer 231; an alignment layer 232; a polymer dispersion type liquid crystal layer 250 sandwiched between the alignment layers 231, 232; a λ/4 phase difference plate 240 positioned at the opposite side of the polymer dispersion type liquid crystal layer 250 of the alignment layer 232; and a reflective layer positioned at the opposite side of the alignment layer 232 of the λ/4 phase difference plate 240. The light projection device 900 projects linear polarized light that oscillates in a first direction to the screen 200 from the alignment film 231 side of the screen 200. The alignment film 231 is rubbed in a direction perpendicular to the first direction, and the twist angle of a liquid crystal molecule 253 is 90°×n (where (n) is an integer of 0 or larger).

Description

  The present invention relates to an image display system.

  2. Description of the Related Art Conventionally, an image display system that irradiates video light from a projector onto a screen and displays an image on the screen is known (for example, Patent Document 1). The screen used in the image display system described in Patent Document 1 has a polymer-dispersed liquid crystal layer and a reflective layer located on the back side of the polymer-dispersed liquid crystal layer. As a reflection type screen, it functions as a scattering type screen when a voltage is applied. However, in such an image display system, there is a problem that the image quality deteriorates when the screen functions as a scattering type.

  That is, in the image display system of Patent Document 1, unpolarized video light is emitted from the projector. Of the image light incident on the polymer dispersed liquid crystal layer from the front side, the polarization component parallel to the alignment direction on the front side of the liquid crystal molecules in the polymer dispersed liquid crystal layer is scattered by the polymer dispersed liquid crystal layer. The orthogonal polarization components are transmitted through the polymer dispersed liquid crystal layer. Similarly, image light reflected by the reflective layer and incident on the polymer dispersed liquid crystal layer from the back side also has a high polarization component parallel to the orientation direction of the liquid crystal molecules in the polymer dispersed liquid crystal layer on the back side. Scattered by the molecular dispersion type liquid crystal layer and orthogonally polarized components are transmitted through the polymer dispersion type liquid crystal layer. Therefore, in such an image display system, an image by the image light incident from the front side and scattered by the polymer dispersed liquid crystal layer and an image by the image light incident from the back side and scattered by the polymer dispersed liquid crystal layer are displayed. Are displayed in a superimposed manner, and a so-called ghost (a phenomenon in which an image appears blurred, a phenomenon in which two images appear to overlap) occurs, and the quality of the image is deteriorated.

JP 2005-10482 A

  An object of the present invention is to provide an image display system capable of displaying a high-quality image by suppressing scattering of image light incident on a polymer dispersed liquid crystal layer from the front side.

Such an object is achieved by the present invention described below.
The image display system of the present invention includes a first alignment film, a second alignment film disposed opposite to the first alignment film, the first alignment film, and the second alignment film, and the liquid crystal molecules and the liquid crystal molecules A polymer-dispersed liquid crystal layer containing a polymer different from the above, a retardation layer that gives a phase difference of ¼ wavelength to light located on the opposite side of the polymer-dispersed liquid crystal layer of the second alignment film, the retardation A reflective layer having a light reflectivity located on a side opposite to the second alignment film of the layer, and switching between a scattering state in which light is scattered and a transmission state in which light is transmitted through the polymer liquid crystal layer And a screen that can
An optical projection device that projects linearly polarized light that vibrates in a first direction on the screen from the first alignment film side of the screen and displays an image on the screen;
The first alignment layer is rubbed in a direction perpendicular to the first direction;
The twist angle of the liquid crystal molecules is 90 ° × n (where n is an integer of 0 or more).
According to such a configuration, it is possible to display a high-quality image by suppressing scattering of linearly polarized light (image light) incident on the polymer dispersed liquid crystal layer from the first alignment film side.

In the image display system of the present invention, the twist angle of the liquid crystal molecules is preferably 0 °.
According to such a configuration, it is possible to effectively suppress scattering (backscattering) of linearly polarized light entering the polymer dispersed liquid crystal layer from the first alignment film side. Therefore, a higher quality image can be displayed.

In the image display system of the present invention, the polymer dispersed liquid crystal layer is preferably a twisted nematic type.
According to such a configuration, the structure of the polymer dispersed liquid crystal layer is simplified.
In the image display system of the present invention, the polymer dispersed liquid crystal layer is preferably a vertical alignment type.
According to such a configuration, the structure of the polymer dispersed liquid crystal layer is simplified.

In the image display system of the present invention, the polymer dispersed liquid crystal layer is divided into a plurality of display regions, and the scattering state and the transmission state can be switched independently for each of the plurality of display regions. Is preferred.
According to such a configuration, the scattering area can be changed in accordance with the contour of the image displayed on the screen.

In the image display system of the present invention, it is preferable that the reflective layer can switch between a reflective state in which light is reflected and a transmissive state in which light is transmitted.
According to such a configuration, the screen can be made transparent when the image display system is not used. Therefore, the feeling of pressure to the surroundings given by the screen can be reduced.

In the image display system of the present invention, the light projection device includes a light source,
A spatial light modulator that modulates the intensity of light emitted from the light source to generate image light;
A projection optical system that projects the image light generated by the spatial light modulator toward the screen;
It is preferable to have a polarization control element that makes the image light generated by the spatial light modulation device linearly polarized light.
According to such a configuration, linearly polarized light can be emitted with a simple configuration.

In the image display system of the present invention, it is preferable that the polarization control element is located on an optical axis between the spatial light modulator and the projection optical system.
According to such a configuration, for example, since the polarization control element can be built in the projector, the configuration of the optical projection device becomes simple.
In the image display system of the present invention, it is preferable that the polarization control element is located on an optical axis between the projection optical system and the screen.
According to such a configuration, for example, since the polarization control element can be disposed outside the projector, the orientation of the polarization control element with respect to the screen can be maintained in a predetermined orientation without being affected by the orientation of the projector. Therefore, it is possible to always project light having a suitable polarization direction onto the screen.

In the image display system of the present invention, the light projection device includes illumination optical systems that emit red light, green light, and blue light that are linearly polarized light, and
A first spatial light modulator that modulates the red light;
A second spatial light modulator for modulating the green light;
A third spatial light modulator that modulates the blue light;
One or two of the red light modulated by the first spatial light modulator, the green light modulated by the second spatial light modulator, and the blue light modulated by the third spatial light modulator It is preferable to have a polarization rotator that rotates the polarization directions of the two lights to align the polarization directions of the red light, the green light, and the blue light.
According to such a configuration, linearly polarized light can be emitted with a simple configuration.

In the image display system of the present invention, the polarization rotator may align the polarization directions of the red light, the green light, and the blue light by rotating the polarization direction of at least one of the red light and the blue light. preferable.
Green light is a component having a higher relative visibility than red light and blue light. Therefore, a bright image can be displayed by rotating the polarization direction of at least one of red light and blue light without rotating the polarization direction of green light and aligning the polarization direction of these lights.

In the image display system of the present invention, the optical projection device includes an illumination optical system that sequentially emits red light, green light, and blue light, which are linearly polarized light that vibrates in the same direction;
It is preferable to have a spatial light modulation device that modulates the red light, the green light, and the blue light.
According to such a configuration, linearly polarized light can be emitted with a simple configuration.

1 is a configuration diagram of an image display system according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view of the screen shown in FIG. 1 (a cross-sectional view taken along line AA in FIG. 1). It is sectional drawing which shows the voltage application state of the screen shown in FIG. FIGS. 3A and 3B are diagrams illustrating polarized light passing through the screen illustrated in FIG. 2, where FIG. 3A corresponds to a cross section taken along line AA in FIG. 1, and FIG. FIG. FIGS. 3A and 3B are diagrams illustrating polarized light passing through the screen illustrated in FIG. 2, where FIG. 3A corresponds to a cross section taken along line AA in FIG. 1, and FIG. 3B corresponds to a cross section taken along line BB in FIG. FIG. It is a graph which shows the screen transmittance | permeability of the linearly polarized light from which a polarization direction differs. It is a top view which shows the structure of the optical system of the projector shown in FIG. It is a top view which shows the relationship between the orientation direction of the liquid crystal molecule contained in a screen, and the polarization direction of the image light irradiated to a screen. It is sectional drawing explaining the effect | action of the screen shown in FIG. It is sectional drawing (the figure corresponding to the AA line cross section in FIG. 1) with which the image display system concerning 2nd Embodiment of this invention is provided, (a) shows a voltage non-application state, (b) Indicates a voltage application state. It is sectional drawing explaining the effect | action of the screen shown in FIG. It is a figure which shows the scattering intensity of the light in a predetermined twist angle. It is sectional drawing (the figure corresponding to the AA line cross section in FIG. 1) with which the image display system concerning 3rd Embodiment of this invention is provided, (a) shows a voltage non-application state, (b) Indicates a voltage application state. It is sectional drawing (the figure corresponding to the AA line cross section in FIG. 1) with which the image display system concerning 4th Embodiment of this invention is provided, (a) shows a voltage non-application state, (b) Indicates a voltage application state. It is sectional drawing of the screen with which the image display system concerning 5th Embodiment of this invention is provided. It is sectional drawing of the screen with which the image display system concerning 6th Embodiment of this invention is provided. It is a top view which shows the structure of the optical system of the projector with which the image display system concerning 7th Embodiment of this invention is provided. It is a top view which shows the structure of the optical system of the projector with which the image display system concerning 8th Embodiment of this invention is provided. It is a top view which shows the structure of the optical system of the projector with which the image display system concerning 9th Embodiment of this invention is provided.

Hereinafter, an image display system of the present invention will be described in detail based on a preferred embodiment shown in the drawings.
<First Embodiment>
FIG. 1 is a configuration diagram of an image display system according to the first embodiment of the present invention. 2 is a cross-sectional view of the screen shown in FIG. 1 (a cross-sectional view taken along line AA in FIG. 1). FIG. 3 is a cross-sectional view showing a voltage application state of the screen shown in FIG. 4 and 5 are diagrams showing polarized light passing through the screen shown in FIG. 2, wherein (a) is a diagram corresponding to the cross section along line AA in FIG. 1, and (b) is B in FIG. It is a figure corresponding to a -B line section. FIG. 6 is a graph showing the screen transmittance of linearly polarized light having different polarization directions. FIG. 7 is a plan view showing the configuration of the optical system of the projector shown in FIG. FIG. 8 is a plan view showing the relationship between the alignment direction of the liquid crystal molecules contained in the screen and the polarization direction of the image light irradiated on the screen. FIG. 9 is a cross-sectional view for explaining the operation of the screen shown in FIG.

  An image display system 100 illustrated in FIG. 1 includes a screen 200, a light projection device 900 that projects an image on the screen 200, and a control unit 400 that controls driving of the screen 200 and the light projection device 900. Such an image display system 100 is a system that projects the video light L ′ from the light projection device 900 onto the front surface of the screen 200 and displays a desired image on the screen 200.

Hereinafter, the screen 200, the light projection device 900, and the control unit 400 will be sequentially described in detail.
(screen)
As shown in FIG. 2, the screen 200 includes a pair of transparent substrates 211 and 212, a pair of electrodes 221 and 222, a pair of alignment films 231 and 232, a λ / 4 phase difference plate 240, and a polymer dispersion type. And a liquid crystal layer 250.
Of the pair of transparent substrates 211 and 212, the transparent substrate 211 is disposed on the front side of the screen 200, and the transparent substrate 212 is disposed on the back side of the screen 200. The transparent substrate 211 supports the electrode 221 and the alignment film 231, and the transparent substrate 212 supports the electrode 222, the alignment film 232, and the λ / 4 retardation plate 240.

  The constituent materials of the transparent substrates 211 and 212 are not particularly limited, and examples thereof include glass materials such as quartz glass and plastic materials such as polyethylene terephthalate. Among these, it is particularly preferable that it is made of a glass material such as quartz glass. As a result, it is possible to obtain a screen 200 that is less likely to warp, bend, or the like and that is more stable.

Of the pair of electrodes 221, 222, the electrode 221 is disposed on the inner surface (the polymer dispersed liquid crystal layer 250 side) of the transparent substrate 211, and the electrode 222 is disposed on the inner surface (the polymer dispersed liquid crystal layer) of the transparent substrate 212. 250 side). The electrode 221 located on the front side is substantially transparent and has light transmission properties, and the electrode 222 located on the back side has light reflectivity and also serves as a reflection layer. The electrode 221 is made of, for example, indium tin oxide (ITO), indium oxide (IO), tin oxide (SnO ₂ ), etc., and the electrode 222 is made of, for example, a metal material such as aluminum.

  The λ / 4 retardation plate 240 is disposed on the inner surface of the electrode 222. The λ / 4 phase difference plate 240 is a phase difference plate that obtains a phase difference of ¼ wavelength in one way. The λ / 4 phase difference plate 240 is installed with its optical crystal axis tilted by approximately 45 ° with respect to the polarization direction (vibration direction) of the image light L ′ described later. According to such a λ / 4 retardation plate 240, the polarization direction of the image light L ″ can be rotated by 90 ° with respect to the polarization direction of the image light L ′, as will be described later, with a simple configuration.

  Of the pair of alignment films 231 and 232, the alignment film (first alignment film) 231 is disposed on the inner surface (the polymer dispersed liquid crystal layer 250 side) of the electrode 221, and the alignment film (second alignment film) 232. Is disposed on the inner surface of the λ / 4 retardation plate 240 (on the polymer dispersion type liquid crystal layer 250 side). The pair of alignment films 231 and 232 are arranged so that their directions coincide. These alignment films 231 and 232 are obtained by, for example, performing an alignment process such as a rubbing process on a film made of polyimide, polyvinyl alcohol, or the like.

  The polymer-dispersed liquid crystal layer 250 can switch between a transmission state (transparent state) and a scattering state when light is incident, depending on the strength of an applied electric field. Such a polymer dispersed liquid crystal layer 250 includes PDLC (polymer dispersed liquid crystal) 251. The PDLC 251 includes liquid crystal molecules 253 and a polymer 252 dispersed in the liquid crystal molecules 253. Note that the polymer 252 and the liquid crystal molecules 253 are different substances. In addition, the polymer 252 and the liquid crystal molecules 253 have a long shape having a major axis direction and a minor axis direction in the shape thereof. The liquid crystal molecules 253 and the polymer 252 each have a predetermined tilt angle along the direction between the alignment films 231 and 232 when no voltage is applied between the pair of electrodes 221 and 222. It has orientation while having it. As described above, since the orientations of the alignment films 231 and 232 are aligned, the twist angle of the liquid crystal molecules 253 is almost 0 °.

  In FIG. 2, the rubbing direction (first direction) of the alignment film 231 is indicated by an arrow A, and the rubbing direction of the alignment film 232 is indicated by an arrow B. Hereinafter, it is also simply referred to as a rubbing direction A or a rubbing direction B. Note that, in the voltage non-application state described later, the alignment direction in the major axis direction of the liquid crystal molecules 253 closest to the alignment film 231 is parallel to the rubbing direction A and the alignment direction in the major axis direction of the liquid crystal molecules 253 closest to the alignment film 232 Is parallel to the rubbing direction B. Therefore, hereinafter, the rubbing direction A and the rubbing direction B are also referred to as an orientation direction A and an orientation direction B.

  Such a PDLC 251 can be formed by, for example, a mixture of a polymer precursor such as a liquid crystalline monomer and liquid crystal molecules. Specifically, the liquid crystal monomer is polymerized by irradiating the mixture with energy such as ultraviolet light while the mixture is aligned by the alignment films 231 and 232. Then, the liquid crystalline monomer is polymerized while maintaining the alignment, and becomes a polymer 252 having an alignment regulating force. The liquid crystal molecules 253 are phase-separated from the polymer 252 and are aligned by the alignment regulating force of the polymer 252.

  The liquid crystal molecules 253 may have any refractive index anisotropy and dielectric anisotropy, and can be appropriately selected from known liquid crystal materials. Further, the liquid crystal molecules 253 have a refractive index in the major axis direction substantially equal to the refractive index in the major axis direction of the polymer 252, and a refractive index in the minor axis direction is substantially equal to the refractive index in the minor axis direction of the polymer 252. Further, a material whose refractive index in the minor axis direction is sufficiently different from the refractive index in the major axis direction of the polymer 252 is used.

The PDLC 251 of this embodiment is a so-called reverse type. Therefore, the polymer-dispersed liquid crystal layer 250 is in a transmissive state having optical transparency when no voltage is applied between the pair of electrodes 221 and 222, and a voltage is applied between the pair of electrodes 221 and 222. When the voltage is applied, the light scattering state is obtained.
More specifically, in the voltage non-applied state, the refractive index is continuous between the liquid crystal molecules 253 and the polymer 252 and light incident on the PDLC 251 is emitted without being diffused, and is in a transmissive state. Become. On the contrary, in the voltage application state, as shown in FIG. 3, the azimuth angle in the major axis direction of the polymer 252 does not change, whereas the azimuth angle in the major axis direction of the liquid crystal molecules 253 changes according to the electric field. Thereby, the incident light is scattered due to the refractive index discontinuously changing between the polymer 252 and the liquid crystal molecule 253, and a light scattering state is obtained.
The “electric field non-application state” is not only a state in which no voltage is applied between the pair of electrodes 221 and 222 but also a level that does not substantially act on the liquid crystal molecules 253 between the pair of electrodes 221 and 222. This includes a state in which a voltage is applied.

  The screen 200 in the diffusion state is incident on the polymer dispersed liquid crystal layer 250 from the front side, diffuses the linearly polarized light L1 that vibrates in a direction parallel to the alignment direction A of the liquid crystal molecules 253 located on the front side, and the alignment direction A It transmits the linearly polarized light L2 that vibrates in the direction orthogonal to the direction. Similarly, the screen 200 in the diffusing state diffuses linearly polarized light that enters the polymer dispersed liquid crystal layer 250 from the back side and vibrates in a direction parallel to the alignment direction B of the liquid crystal molecules 253 located on the back side. It has the property of transmitting linearly polarized light that vibrates in a direction orthogonal to direction B.

  More specifically, light incident on the polymer dispersed liquid crystal layer 250 from the front side passes through the polymer 252 and the liquid crystal molecules 253 alternately. At this time, the linearly polarized light L1 passes through the polymer 252 in the minor axis direction and the liquid crystal molecules 253 in the major axis direction as shown in FIGS. 4 (a) and 4 (b). As described above, since the refractive index in the minor axis direction of the polymer 252 and the refractive index in the major axis direction of the liquid crystal molecules 253 are different, the linearly polarized light L1 is generated at the interface between the polymer 252 and the liquid crystal molecules 253. Scattered. On the other hand, as shown in FIGS. 5A and 5B, the linearly polarized light L2 passes the polymer 252 in the minor axis direction and the liquid crystal molecules 253 in the minor axis direction. As described above, since the refractive index in the minor axis direction of the polymer 252 and the refractive index in the minor axis direction of the liquid crystal molecules 253 are substantially equal, the linearly polarized light L2 is almost at the interface between the polymer 252 and the liquid crystal molecules 253. The light passes through the polymer dispersed liquid crystal layer 250 as it is without being scattered. The same applies to the light incident on the polymer dispersed liquid crystal layer 250 from the back side.

FIG. 6 shows an example of the transmittance of the linearly polarized light L1 and L2. As apparent from FIG. 6, the linearly polarized light L <b> 1 hardly transmits through the polymer dispersed liquid crystal layer 250 and is mostly scattered within the polymer dispersed liquid crystal layer 250. On the other hand, the linearly polarized light L 2 hardly scatters in the polymer dispersed liquid crystal layer 250, and most of the linearly polarized light L 2 is transmitted through the polymer dispersed liquid crystal layer 250.
Note that, by setting the thickness of the polymer dispersed liquid crystal layer 250 to 10 μm or more, the scattering of the linearly polarized light L1 as described above can be sufficiently generated. That is, the transmittance of the linearly polarized light L1 can be suppressed to 1% or less.

(Light projection device)
The light projection device 900 includes a projector 600 and a polarization control element 800 that performs polarization control of the image light L emitted from the projector 600 (see FIG. 1).
As shown in FIG. 7, the projector 600 includes a light source device 620, a uniform illumination optical system 630, a spatial light modulation device 640, and a projection optical system (projection lens group) 650. Such a projector 600 forms a light image (that is, video light L) by modulating the intensity of light emitted from the light source device 620 by the spatial light modulation device 640 according to the given image information, and this light. This is an optical apparatus for enlarging and projecting an image on the screen 200 from the projection optical system 650.

The light source device 620 includes an ultra-high pressure mercury lamp 621 that is a light source and a reflector 622. In such a configuration, the light emitted from the extra-high pressure mercury lamp 621 is reflected by the reflector 622 and converged to the front side. In addition, as a light source, you may employ | adopt not only an ultrahigh pressure mercury lamp but a metal halide lamp etc., for example.
The uniform illumination optical system 630 includes a rod integrator 631, a color wheel 632, a relay lens group 633, and a reflection mirror 634. In such a uniform illumination optical system 630, the light beam emitted from the light source device 620 passes through the color wheel 632 and then enters the rod integrator 631 at an angle.

  The color wheel 632 is rotatably provided by a driving source such as a motor (not shown). Further, the color wheel 632 is formed with a filter surface 632a facing a port formed at the incident side end of the rod integrator 631, and the filter surface 632a has R (red), G (green), B (blue) three-color filters are formed side by side in the circumferential direction across an area. The color wheel 632 may be provided on the emission side of the rod integrator 631.

  The light beam incident on the color wheel 632 is color-separated in time series into three colors of red (R) light, green (G) light, and blue (B) light by the filter surface 632a. The separation into the three colors R, G, and B is performed at a frequency faster than the frame frequency of the image displayed on the screen 200. By performing color separation at such a frequency, a full color image can be displayed on the screen 200.

The light (R light, G light, B light) that has passed through the color wheel 632 is introduced into the inside of the incident port of the rod integrator 631. The light introduced into the rod integrator 631 is reflected a plurality of times in the rod integrator 631, thereby ensuring a uniform illuminance on the exit surface of the rod integrator 631. Therefore, the light emitted from the emission port of the rod integrator 631 has a uniform illumination distribution.
The light emitted from the rod integrator 631 enters the spatial light modulator 640 as uniform illumination light via the relay lens group 633 and the reflection mirror 634.

  The spatial light modulation device 640 includes a substrate 641 and a plurality of light modulation elements 642 arranged on the substrate (for example, DMD (Digital Micromirror Device: “DMD” is registered by Texas Instruments Incorporated, USA). Trademark)). The plurality of light modulation elements 642 are arranged in a matrix on the substrate 641. The number of light modulation elements 642 is not particularly limited. In the projector 600, since one light modulation element 642 constitutes one pixel, the light modulation elements 642 are arranged in the number of pixels, for example, horizontal × vertical = 1280 × 1024, 640 × 480.

Each light modulation element 642 has a movable mirror for reflecting an incident light beam, and this movable mirror has an ON state in which the reflected light is guided to the projection optical system 650 and an inclination with respect to the ON state. In contrast, the posture changes to an OFF state in which the reflected light is guided to an absorber (not shown).
The spatial light modulator 640 forms a predetermined light image by independently switching the ON / OFF state of each light modulation element 642 based on image information given from, for example, a PC (personal computer) 500 or the like. . The formed optical image is incident on the projection optical system 650.

The projection optical system 650 includes a projection lens 651, and projects the light image guided to the projection optical system 650 as video light L in the direction of the screen 200.
The polarization control element 800 positioned in front of the projection optical system 650 is a polarizer that obtains linearly polarized light (image light L ′) that vibrates in a predetermined direction from the image light L that is random polarization emitted from the projector 600. Such a polarization control element 800 is not particularly limited as long as the above effect can be exhibited, and for example, a known polarizer such as a wire grid array or a liquid crystal device can be used.

  With such a configuration, the configuration of the optical projection device 900 can be simplified. Further, in the optical projection device 900, the polarization control element 800 is located downstream of the projection optical system 650 in the traveling direction of the image light L. In other words, the polarization control element 800 is provided separately from the projector 600, and is disposed on the optical axis between the projector 600 (that is, the projection optical system 650) and the screen 200. With such a configuration, the orientation of the polarization control element 800 with respect to the screen 200 can be maintained in a predetermined orientation regardless of the orientation of the projector 600. Therefore, the image light L ′ that always vibrates in a predetermined direction is obtained by the polarization control element 800.

As shown in FIG. 8, the polarization direction C of the image light L ′ is orthogonal to the rubbing direction A of the alignment film 231 on the front side of the screen 200. Thus, by making the polarization direction C orthogonal to the rubbing direction A, a high-quality image (video) can be displayed on the screen 200.
More specifically, based on FIG. 9, as described above, the linearly polarized light that enters the polymer dispersed liquid crystal layer 250 from the front side and vibrates in the direction orthogonal to the rubbing direction A is polymer dispersed. It passes through the liquid crystal layer 250 with little scattering. Therefore, the image light L ′ incident on the polymer dispersion type liquid crystal layer 250 is hardly scattered in the polymer dispersion type liquid crystal layer 250, and is generated by the image light L ′ incident on the polymer dispersion type liquid crystal layer 250 from the front side. No image is displayed on the screen 200.

  The video light L ′ that has passed through the polymer dispersed liquid crystal layer 250 passes through the λ / 4 retardation plate 240 and is then reflected by the electrode 222. The image light L ′ reflected and traveling toward the front side passes through the λ / 4 phase difference plate 240 again. Thus, the image light L ′ passes through the λ / 4 retardation plate 240 twice, so that the polarization direction of the image light L ′ is rotated by 90 ° (the image light after rotation is also referred to as “image light L” ”). say). Therefore, the polarization direction D of the video light L ″ is parallel to the rubbing direction B of the alignment film 232. As described above, the light enters the polymer dispersed liquid crystal layer 250 from the back side and is parallel to the rubbing direction B. The linearly polarized light that oscillates in the direction is scattered by the polymer dispersed liquid crystal layer 250. Therefore, most of the image light L ″ incident on the polymer dispersed liquid crystal layer 250 from the back side is in the polymer dispersed liquid crystal layer 250. And the image is displayed on the screen 200 by the scattered video light L ″.

  Thus, on the screen 200, no image is displayed by the video light L ′ incident on the polymer dispersed liquid crystal layer 250 from the front side, and the video light L ″ incident on the polymer dispersed liquid crystal layer 250 from the rear side. As a result, the image light that is incident on the polymer dispersed liquid crystal layer from the front side and the polymer dispersed type from the back side can be displayed. When an image is displayed by both the image light incident on the liquid crystal layer, these two images are displayed in a shifted state, resulting in a blurred outline or double overlapping images. On the other hand, on the screen 200, since the image is displayed by the video light L ″ incident on the polymer dispersed liquid crystal 250 from the back side, the conventional problem does not occur. High picture It is possible to display quality.

  In particular, in the screen 200, the rubbing directions of the alignment films 231 and 232 are aligned, and the liquid crystal molecules 253 between them are arranged in a 0 ° alignment without being twisted (that is, the twist angle is 0 °). ), Selection of scattering / transmission of image light as described above can be performed with higher accuracy. Therefore, the above-described effect becomes more remarkable. Further, by arranging the liquid crystal molecules 253 with 0 ° orientation, it is possible to more effectively suppress the scattering of the video light L ′ incident on the polymer dispersed liquid crystal layer 250 from the front side, so that higher image quality is achieved. Can be displayed.

  In addition, since most of the image light L ″ is scattered in the polymer dispersed liquid crystal layer 250 on the screen 200, bright spots (notably higher than the surroundings) caused by light passing through the polymer dispersed liquid crystal layer 250 without being scattered. In this respect, the screen 200 enables display with high image quality and further reduces eye strain of the observer.

  Note that the polarization direction C is “perpendicular” to the alignment direction A when the polarization direction C is orthogonal to the alignment direction A, that is, the angle between the polarization direction C and the alignment direction A is In addition to the case of 90 °, the case where the angle formed by the polarization direction C and the alignment direction A is slightly shifted from 90 ° is also included. Specifically, the case where the angle formed between the polarization direction C and the alignment direction A is within 80 ° to 100 ° is also included. If it is in such a range, the effect as mentioned above can fully be exhibited.

  Similarly, the polarization direction D is “parallel” with the alignment direction B when the polarization direction D and the alignment direction B are parallel, that is, when the angle between the polarization direction D and the alignment direction B is 0 °. In addition, the case where the angle formed by the polarization direction D and the alignment direction B is slightly deviated from 0 ° is also included. Specifically, the case where the angle formed by the polarization direction B and the alignment direction D is within 10 ° is also included. If it is in such a range, the effect as mentioned above can fully be exhibited.

(Control part)
As shown in FIG. 1, for example, the control unit 400 performs predetermined processing on the image signal I from the personal computer 500 and transmits the image signal I ′ obtained by the processing to the projector 600. And a screen control unit 420 that controls driving (ON / OFF) of the screen 200 based on a signal from the personal computer 500. Receiving the image signal from the image signal processing unit 410, the projector 600 emits video light L based on the image signal.

  The control unit 400 is configured to control the driving of the screen 200 by the screen control unit 420 in response to the output of the image signal I ′ from the image signal processing unit 410 to the projector 600. Specifically, in a state where the image signal processing unit 410 does not output the image signal I ′, the control unit 400 causes the screen control unit 420 to set the screen 200 to a light transmission state. On the contrary, in the state where the image signal I ′ is output from the image signal processing unit 410, the control unit 400 causes the screen control unit 420 to set the screen 200 in a light scattering state.

  According to such a control unit 400, when the image light L ′ transmitted through the polarization control element 800 is not emitted from the light projection device 900, that is, when there is no image to be displayed on the screen 200, the screen 200 is transmitted through the screen 200. It can be. Further, when the image light L ′ transmitted through the polarization control element 800 is emitted from the light projection device 900, the screen 200 can be in a scattering state, and an image corresponding to the image light L ′ is displayed on the screen 200. can do.

The image display system 100 according to the present embodiment has been described above.
In this embodiment, as the screen 200, the back-side electrode 222 also serves as a reflective layer that reflects the image light L ′. However, if the image light L ′ can be reflected to the front side, the configuration of the screen 200 Is not limited to this embodiment. For example, the electrode 222 may be the same electrode as the electrode 221, and the transparent substrate 212 on the back side may be changed to a light reflective metal substrate, and the metal substrate may also serve as a reflective layer that reflects the video light L ′. . For example, the electrode 222 may be the same electrode as the electrode 221, and a reflective film (reflective layer) may be disposed between the electrode 222 and the transparent substrate 212.

Second Embodiment
Next, a second embodiment of the image display system of the present invention will be described.
FIG. 10 is a cross-sectional view of a screen included in the image display system according to the second embodiment of the present invention (a view corresponding to a cross section taken along line AA in FIG. 1), and FIG. FIG. 10B shows a voltage application state. FIG. 11 is a cross-sectional view for explaining the operation of the screen shown in FIG. FIG. 12 is a diagram showing the light scattering intensity at a predetermined twist angle.

Hereinafter, the image display system according to the second embodiment will be described with a focus on differences from the above-described embodiment, and description of similar matters will be omitted.
The image display system according to the second embodiment of the present invention is the same as that of the first embodiment described above except that the configuration of the screen is different. In addition, the same code | symbol is attached | subjected to the structure similar to embodiment mentioned above.

  As shown in FIG. 10, in the screen 200A, the rubbing directions of the alignment films 231 and 232 are arranged so as to be shifted by 90 °. Correspondingly, the major axis direction of the liquid crystal molecules 253 positioned between the alignment films 231 and 232 is continuously twisted by 90 °. That is, the polymer dispersed liquid crystal layer 250 is a twisted nematic liquid crystal layer. By making the polymer dispersed liquid crystal layer 250 to be twisted nematic, the configuration of the screen 200A can be simplified.

The image light L ′ (L ″) passing through the polymer dispersed liquid crystal layer 250 is rotated by 90 ° along the polymer 252. Here, the optical rotation of the image light L ′ (L ″) is increased. An influencing factor is the polymer 252.
The image light L ′ incident on the polymer dispersed liquid crystal layer 250 in a voltage applied state from the front side passes through the polymer 252 in the minor axis direction and passes through the liquid crystal molecules 253 in the minor axis direction while rotating. On the other hand, the image light L ″ incident on the polymer dispersed liquid crystal layer 250 in the voltage application state from the back side passes through the polymer 252 in the major axis direction and passes through the liquid crystal molecules 253 in the minor axis direction while rotating. Therefore, as shown in Fig. 11, the image light L 'is transmitted through the polymer dispersed liquid crystal layer 250 with almost no scattering, and most of the image light L "is within the polymer dispersed liquid crystal layer 250. Scatter at.

According to the second embodiment as described above, the same effects as those of the first embodiment described above can be obtained.
In the screen 200A of the present embodiment, the twist (twist angle) of the liquid crystal molecules 253 is set to 90 °, but the twist angle of the liquid crystal molecules 253 is not limited to 90 ° and is an integral multiple of 90 °. I just need it. That is, the twist angle may be 90 ° × n (where n is an integer of 1 or more). In addition, if it exists in the range of (90 degrees xn) +/- 10 degrees, said effect can fully be exhibited.

When the twist angle is an even multiple of 90 °, such as 180 °, 360 °, etc., as shown in FIG. 12A, it has a uniform scattering intensity of the image light L ″ in all angle directions. A light distribution that does not depend on the viewing angle with respect to the angular direction can be shown, and the screen 200A is bright and has a wide viewing angle in all angular directions.
Further, when the twist angle is an odd multiple of 90 ° such as 270 ° and 450 °, as shown in FIG. 12B, the scattering intensity of the image light L ″ of the polymer dispersed liquid crystal layer 250 is different. Therefore, for example, in order to increase the horizontal brightness and viewing angle of the screen 200A, the alignment directions A and B are set so that the scattering intensity extends along the horizontal direction of the screen 200A. On the contrary, in order to increase the vertical brightness and viewing angle of the screen 200A, the orientation directions A and B are defined so that the scattering intensity extends along the vertical direction of the screen 200A. Good.

<Third Embodiment>
Next, a third embodiment of the image display system of the present invention will be described.
FIG. 13 is a cross-sectional view of a screen provided in the image display system according to the third embodiment of the present invention (a view corresponding to a cross section taken along line AA in FIG. 1), and FIG. , (B) shows a voltage application state.

Hereinafter, the image display system according to the third embodiment will be described focusing on the differences from the above-described embodiment, and description of similar matters will be omitted.
The image display system according to the third embodiment of the present invention is the same as that of the first embodiment described above except that the screen configuration (configuration of the polymer-dispersed liquid crystal layer) is different. In addition, the same code | symbol is attached | subjected to the structure similar to embodiment mentioned above.

  In the polymer dispersed liquid crystal layer 250B of the screen 200B shown in FIG. 13, the liquid crystal molecules 253B and the polymer 252B are aligned between the alignment films 231 and 232 in the voltage non-application state (initial state), respectively. Thus, the molecules are oriented so that the major axis direction of each molecule is substantially perpendicular while having a predetermined tilt angle. That is, the polymer dispersed liquid crystal layer 250B is a vertical alignment type liquid crystal layer. By using the polymer dispersion type liquid crystal layer 250B as a vertical alignment type liquid crystal layer, the configuration of the screen 200B is simplified.

The liquid crystal molecules 253B may have any refractive index anisotropy and negative dielectric anisotropy, and can be appropriately selected from known liquid crystal materials. Further, the liquid crystal molecules 253B have a refractive index in the major axis direction substantially equal to the refractive index in the major axis direction of the polymer 252B, and a refractive index in the minor axis direction is substantially equal to the refractive index in the minor axis direction of the polymer 252B. Further, a material having a refractive index in the minor axis direction sufficiently different from that in the major axis direction of the polymer 252B is used.
The PDLC 251B is a so-called reverse type. Therefore, the polymer-dispersed liquid crystal layer 250B is in a transmissive state having optical transparency when no voltage is applied between the pair of electrodes 221 and 222, and a voltage is applied between the pair of electrodes 221 and 222. When the voltage is applied, the light scattering state is obtained.

  More specifically, as shown in FIG. 13A, in the state where no voltage is applied, the refractive index is continuous between the liquid crystal molecules 253B and the polymer 252B, and almost no light is incident on the PDLC 251B. The light is emitted without being diffused and enters a transmission state. On the other hand, as shown in FIG. 13B, the azimuth angle in the major axis direction of the polymer 252B does not change in the voltage application state, whereas the azimuth angle in the major axis direction of the liquid crystal molecule 253B depends on the electric field. As a result, the refractive index discontinuously changes between the polymer 252B and the liquid crystal molecules 253B, so that the incident light is scattered and emitted to be in a scattering state.

In the scattering state, the alignment direction A on the alignment film 231 side of the liquid crystal molecules 253B is orthogonal to the polarization direction of the image light L ′ incident on the polymer dispersed liquid crystal layer 250B from the front side, and the liquid crystal molecules 253B The alignment direction B on the alignment film 232 side is parallel to the polarization direction of the image light L ″ incident on the polymer dispersed liquid crystal layer 250B from the back side.
According to the third embodiment as described above, the same effects as those of the first embodiment described above can be obtained.

<Fourth embodiment>
Next, a fourth embodiment of the image display system of the present invention will be described.
FIG. 14 is a cross-sectional view of a screen provided in the image display system according to the fourth embodiment of the present invention (a view corresponding to the cross section taken along the line AA in FIG. 1), and FIG. FIG. 14B shows a voltage application state.

Hereinafter, the image display system according to the fourth embodiment will be described focusing on the differences from the above-described embodiment, and description of similar matters will be omitted.
The image display system according to the fourth embodiment of the present invention is the same as that of the third embodiment described above except that the screen has a twist angle. In addition, the same code | symbol is attached | subjected to the structure similar to embodiment mentioned above.

  The polymer dispersed liquid crystal layer 250F of the screen 200F shown in FIG. 14 is a vertical alignment type liquid crystal layer as in the third embodiment. In the screen 200F, the rubbing directions of the alignment films 231 and 232 are arranged with a 90 ° deviation. Correspondingly, the major axis direction of the liquid crystal molecules 253B located between the alignment films 231 and 232 is continuously twisted by 90 °.

  The image light L ′ (L ″) passing through the polymer dispersed liquid crystal layer 250F is rotated by 90 ° along the polymer 252B. Here, the optical rotation of the image light L ′ (L ″) is increased. An influencing factor is the polymer 252B. In general, in the polymer dispersed liquid crystal layer 250F having the above-described configuration, the content of the liquid crystal molecules 253B is about 90% or more, which is very high compared to the polymer 252B. Therefore, the image light L ′ (L ″) can be sufficiently rotated along the liquid crystal molecules 253B.

The image light L ′ incident on the polymer dispersed liquid crystal layer 250F in the voltage application state (the state of FIG. 14B) from the front side passes through the polymer 252B in the major axis direction while rotating, and the liquid crystal molecules 253B. Through the major axis. On the other hand, the image light L ″ incident on the polymer dispersed liquid crystal layer 250F in the voltage application state from the back side passes through the polymer 252B in the major axis direction and passes through the liquid crystal molecules 253B in the minor axis direction while rotating. Therefore, the image light L ′ is transmitted through the polymer dispersed liquid crystal layer 250 with little scattering, and most of the image light L ″ is scattered within the polymer dispersed liquid crystal layer 250F. As described above, in the present embodiment, the incident light can be sufficiently rotated, so that excellent light scattering properties can be exhibited.
According to the fourth embodiment as described above, the same effects as those of the first embodiment described above can be obtained.

<Fifth Embodiment>
Next, a fifth embodiment of the image display system of the present invention will be described.
FIG. 15: is sectional drawing of the screen with which the image display system concerning 5th Embodiment of this invention is provided.
Hereinafter, the image display system according to the fifth embodiment will be described with a focus on differences from the above-described embodiment, and description of similar matters will be omitted.

The image display system according to the fifth embodiment of the present invention is the same as that of the first embodiment described above except that the configuration of the screen is different. In addition, the same code | symbol is attached | subjected to the structure similar to embodiment mentioned above.
A screen 200 </ b> C illustrated in FIG. 15 includes a reflective layer 260 disposed between the electrode 222 and the transparent substrate 212. Note that the electrode 222 is transparent and light-transmitting like the electrode 221.

  The reflective layer 260 can select a reflective state (mirror state) that reflects light and a transmissive state (transparent state) that transmits light. The configuration of the reflective layer 260 is not particularly limited as long as the reflective state and the transmissive state can be switched. For example, a dimming mirror can be applied. As the light control mirror, a gas chromic system that switches the reflection state / transmission state by hydrogen / oxygen atmosphere control, an electrochromic system that switches the reflection state / transmission state by electrochemical action (voltage control), or the like is used. it can.

An example of an electrochromic modulation mirror is a transparent base material made of glass, plastic, etc., a transparent conductive film made of indium tin oxide (ITO), etc., and made of tungsten oxide (WO ₃ ). Ion storage layer, solid electrolyte layer composed of tantalum oxide (Ta ₂ O ₅ ), buffer layer composed of aluminum (Al), catalyst layer composed of palladium (Pd), magnesium nickel (Mg—Ni) It is the structure which laminated | stacked the transmission / reflection layer comprised with the alloy in order.

Such a modulation mirror is in a reflective state in the initial state. In this state, when a positive voltage is applied between the transparent conductive film and the transmissive / reflective layer, hydrogen ions (H ⁺ ) stored in the ion storage layer move into the transmissive / reflective layer, resulting in a metallic state. The Mg—Ni alloy at is in a non-metallic state by hydrogenation. As a result, the dimming mirror changes from the reflective state to the transparent state. When a negative voltage is applied to the light control mirror in the transparent state, hydrogen ions in the transmission / reflection layer return to the ion storage layer, and the light control mirror changes to the original reflection state. Each state of such a modulation mirror is maintained even when the voltage is turned off.

According to such a screen 200C, when the screen 200C is not used, the reflective layer 260 can be made transparent and the screen 200C can be made transparent. Therefore, for example, when the screen 200C is used in a living space, it is possible to reduce the feeling of pressure given by the screen 200C.
According to the fifth embodiment as described above, the same effects as those of the first embodiment described above can be obtained.

<Sixth Embodiment>
Next, a sixth embodiment of the image display system of the present invention will be described.
FIG. 16: is sectional drawing of the screen with which the image display system concerning 6th Embodiment of this invention is provided.
Hereinafter, the image display system according to the sixth embodiment will be described with a focus on differences from the above-described embodiments, and description of similar matters will be omitted.
The image display system according to the sixth embodiment of the present invention is the same as that of the fifth embodiment described above except that the configuration of the screen is different. In addition, the same code | symbol is attached | subjected to the structure similar to embodiment mentioned above.

  As shown in FIG. 16, in the screen 200 </ b> D of this embodiment, the back-side electrodes 222 are partitioned (divided) in a matrix form. In such a screen 200D, a region where the electrode 221 and one electrode 222 overlap constitutes one display region S, and voltage application can be controlled for each display region S using an active matrix circuit or the like. That is, the transmission state / scattering state can be switched independently for each display region S. The number of display areas S is not particularly limited, and the width × length may be 2 × 2. Alternatively, the horizontal x vertical may be set to 800 x 600, and the pixel of the projector 600 may be made equal.

  Although not shown, the reflective layer 260 is also divided and formed (partition formation) into a plurality of regions corresponding to the arrangement of the display regions S, and the reflection state / transmission state can be switched independently for each region. it can. In addition, the state of each area is controlled in conjunction with the display area S overlapping therewith. Specifically, the state of each region is controlled such that when the corresponding display region S is in the scattering state, it is in the reflective state, and when the corresponding display region S is in the transmissive state, it is in the transmissive state.

  In such a screen 200D, since the transmission state / scattering state can be selected for each display region S, the region in the scattering state can be freely changed. Therefore, the contour of the scattering region can be matched with the contour of the image displayed by the projector 600, and the periphery of the image can be made transparent. As a result, a more realistic image can be displayed.

<Seventh embodiment>
Next, a seventh embodiment of the image display system of the present invention will be described.
FIG. 17 is a plan view showing the configuration of the optical system of the projector provided in the image display system according to the seventh embodiment of the present invention.
Hereinafter, the image display system according to the seventh embodiment will be described with a focus on differences from the above-described embodiment, and description of similar matters will be omitted.
The image display system according to the seventh embodiment of the present invention is the same as that of the first embodiment described above except that the polarization control element is built in the projector. In addition, the same code | symbol is attached | subjected to the structure similar to 1st Embodiment mentioned above.

As shown in FIG. 17, the polarization control element 800 is built in the projector 600. Specifically, the polarization control element 800 is on the optical axis between the spatial light modulator 640 and the projection optical system 650, that is, on the upstream side in the traveling direction of the image light L and the image light L ′ from the projection optical system 650. Is located. As described above, the configuration of the image display system 100 can be simplified by incorporating the polarization control element 800 in the projector 600.
Also according to the sixth embodiment, the same effects as those of the first embodiment described above can be obtained.

<Eighth Embodiment>
Next, an eighth embodiment of the image display system of the present invention will be described.
FIG. 18 is a plan view showing the configuration of the optical system of the projector provided in the image display system according to the eighth embodiment of the present invention.
Hereinafter, the image display system according to the eighth embodiment will be described with a focus on differences from the above-described embodiments, and description of similar matters will be omitted.

The image display system according to the eighth embodiment of the present invention is the same as that of the first embodiment described above except that the configuration of the light projection device is different. In addition, the same code | symbol is attached | subjected to the structure similar to embodiment mentioned above.
As shown in FIG. 18, a projector 300 that is a light projection device includes an illumination optical system 310, a color separation optical system 320, parallelizing lenses 330R, 330G, and 330B, spatial light modulators 340R, 340G, and 340B, It has a cross dichroic prism 350, a projection optical system (projection lens group) 360, and a polarization rotator 370.

The illumination optical system 310 includes a light source 311, a reflector 312, a first lens array 313, a second lens array 314, a polarization conversion element 315, and a superimposing lens 316.
The light source 311 is an ultra-high pressure mercury lamp, and the reflector 312 has a parabolic mirror. The radial light beam emitted from the light source 311 is reflected by the reflector 312 to become a substantially parallel light beam, and is emitted to the first lens array 313. The light source 311 is not limited to the ultra-high pressure mercury lamp, and may be a metal halide lamp, for example. Further, the reflector 312 is not limited to a parabolic mirror, and a configuration in which a collimating concave lens is disposed on the exit surface of the reflector 312 formed of an ellipsoidal mirror may be employed.

  The first lens array 313 and the second lens array 314 are formed by arranging small lenses in a matrix. The light beam emitted from the light source 311 is divided into a plurality of minute partial light beams by the first lens array 313, and each partial light beam is divided into three spatial lights to be illuminated by the second lens array 314 and the superimposing lens 316. Superimposed on the surfaces of the modulation devices 340R, 340G, 340B.

The polarization conversion element 315 has a function of aligning a randomly polarized light beam with linearly polarized light (S-polarized light or P-polarized light) that vibrates in one direction. In this embodiment, the loss of the light beam in the color separation optical system 320 is reduced. Aligned with a small amount of S-polarized light.
The color separation optical system 320 has a function of separating the light beam emitted from the illumination optical system 310 into three color lights of red (R) light, green (G) light, and blue (B) light, A B light reflecting dichroic mirror 321, an RG light reflecting dichroic mirror 322, a G light reflecting dichroic mirror 323, and reflecting mirrors 324 and 325 are provided.

  Of the light beam emitted from the illumination optical system 310, the B light component is reflected by the B light reflecting dichroic mirror 321 and further reflected by the reflecting mirrors 324 and 361 to reach the collimating lens 330B. On the other hand, of the light beam emitted from the illumination optical system 310, the components of G light and R light are reflected by the RG light reflecting dichroic mirror 322 and further reflected by the reflecting mirror 325 to reach the G light reflecting dichroic mirror 323. The component of G light therein is reflected by the G light reflecting dichroic mirror 323 and the reflecting mirror 362 and reaches the collimating lens 330G, and the component of R light is transmitted through the G light reflecting dichroic mirror 323 and reflected by the reflecting mirror 363. To the collimating lens 330R.

The collimating lenses 330R, 330G, and 330B are configured so that the partial light beams become substantially parallel light beams so as to illuminate the spatial light modulators 340R, 340G, and 340B, respectively, with a plurality of partial light beams from the illumination optical system 310. Is set to
The R light transmitted through the collimating lens 330R reaches the spatial light modulation device (first spatial light modulation device) 340R, and the G light transmitted through the parallelizing lens 330G is the spatial light modulation device (second spatial light modulation device). The B light reaching 340G and transmitted through the collimating lens 330B reaches the spatial light modulator (third spatial light modulator) 340B.

  The spatial light modulation device 340R is a spatial light modulation device that modulates R light according to an image signal, and is a transmissive liquid crystal display device (LCD). A liquid crystal panel (not shown) provided in the spatial light modulation device 340R encloses a liquid crystal layer for modulating light according to an image signal between two transparent substrates. The R light modulated by the spatial light modulation device 340R enters a cross dichroic prism 350 that is a color synthesis optical system. The configurations and functions of the spatial light modulation devices 340G and 340B are the same as those of the spatial light modulation device 340R.

  The cross dichroic prism 350 is formed into a prismatic shape having a substantially square cross section by bonding four prisms having a triangular prism shape. Dielectric multilayer films 351 and 352 are formed along the X-shaped bonding surface. Is provided. The dielectric multilayer film 351 transmits G light and reflects R light, and the dielectric multilayer film 352 transmits G light and reflects B light. Then, the cross dichroic prism 350 forms the image light representing the color image by combining the modulated lights of the respective color lights emitted from the spatial light modulators 340R, 340G, and 340B from the incident surfaces 350R, 350G, and 350B, respectively. Then, the image light is emitted toward the projection optical system 360.

  A polarization rotator 370 is disposed between the cross dichroic prism 350 and the projection optical system 360. The polarization rotator 370 has wavelength selectivity and functions to rotate the polarization direction of light of a predetermined wavelength by 90 ° (that is, a function to convert S-polarized light to P-polarized light or P-polarized light to S-polarized light). have. The polarization rotator 370 is not particularly limited, and for example, Color Select (registered trademark) manufactured by Coloring Co., Ltd. can be used.

  Since the cross dichroic prism 350 is a single-polarization element that reflects S-polarized light and transmits P-polarized light, the R light and B light reflected by the cross dichroic prism 350 are converted to S-polarized light and G is transmitted through the cross dichroic prism 350. The light needs to be P-polarized light. As described above, since the polarization directions of the R light, B light, and G light emitted from the cross dichroic prism 350 are different, the polarization rotator 370 is arranged to align the polarization directions of the R light, G light, and B light. Has been.

  The polarization rotator 370 is configured to rotate the polarization of the R light and the B light by 90 ° and not to rotate the change of the G light. Therefore, the R light, G light, and B light that have passed through the polarization rotator 370 have the same polarization direction. Here, the G light is a component having a higher relative visibility than the R light and the B light. Therefore, unlike the polarization rotator 370, by aligning the polarization directions of the R light, G light, and B light without rotating the polarization of the G light, the loss of the G light is suppressed, and a bright image display is provided for the observer. It becomes possible.

The image light that has passed through the polarization rotator 370 is emitted from the projection optical system 360 as image light L ′.
According to the projector 600 having such a configuration, since the image light L ′ that is linearly polarized light can be emitted, the polarization control element 800 as in the first embodiment described above becomes unnecessary, and the configuration of the image display system 100. Is simplified.

According to the eighth embodiment as described above, the same effects as those of the first embodiment described above can be obtained.
In the present embodiment, a projector using three transmissive liquid crystal display devices (LCD) has been described, but the configuration of the projector is not limited to this. For example, a configuration using three reflective liquid crystal display (LCD) devices may be used. In addition, a configuration using two liquid crystal display devices may be used regardless of transmission type / reflection type. In other words, the present embodiment can be applied to any projector that uses polarized light and uses two or more microdisplays.

<Ninth Embodiment>
Next, a ninth embodiment of the image display system of the present invention will be described.
FIG. 19 is a plan view showing the configuration of the optical system of the projector provided in the image display system according to the ninth embodiment of the present invention.
Hereinafter, the image display system according to the ninth embodiment will be described with a focus on differences from the above-described embodiment, and description of similar matters will be omitted.

The image display system according to the ninth embodiment of the present invention is the same as that of the first embodiment described above except that the configuration of the light projection device is different. In addition, the same code | symbol is attached | subjected to the structure similar to embodiment mentioned above.
As shown in FIG. 19, a projector 700 as an optical projection device has a light source unit 710, a PBS (polarization beam splitter) prism 730, a reflective liquid crystal panel 740, and a projection optical system (projection lens group) 750. doing.

The light source unit 710 includes red, green, and blue laser light sources 711R, 711G, and 711B, collimator lenses 712R, 712G, and 712B provided for the laser light sources 711R, 711G, and 711B and dichroic mirrors 713R, 713G, and 713B. And.
The laser light sources 711R, 711G, and 711B each have a light source and a drive circuit (not shown). The laser light source 711R emits red laser light, the laser light source 711G emits green laser light, and the laser light source 711B emits blue laser light. The laser beams of the respective colors emitted from these laser light sources 711R, 711G, and 711B are linearly polarized light and have the same polarization direction (vibration direction of light) (for example, S wave).

  The laser beams of the respective colors emitted from the laser light sources 711R, 711G, and 711B are collimated by the collimator lenses 712R, 712G, and 712B and enter the dichroic mirrors 713R, 713G, and 713B. The dichroic mirror 713R has a characteristic of reflecting red laser light. The dichroic mirror 713B has characteristics of reflecting blue laser light and transmitting red laser light. The dichroic mirror 713G has characteristics of transmitting green laser light and reflecting red and blue laser lights.

  The driving of the laser light sources 711R, 711G, and 711B is controlled so as to blink sequentially, whereby red laser light, green laser light, and blue laser light are sequentially emitted. The emitted laser light of each color passes through a collimator lens and a dichroic mirror, is reflected by a reflection surface of a PBS (polarization beam splitter) prism 730, and is projected on a reflective liquid crystal panel 740.

The reflective liquid crystal panel 740 is an LCOS (Liquid Crystal on Silicon) and has a reflective layer. Accordingly, the laser beams of the respective colors reflected by the reflection layer and passed through the PBS prism 730 are emitted from the projection optical system 750 as the image light L ′. The laser light of each color reflected by the reflective liquid crystal panel 740 has a polarization direction rotated by 90 ° and becomes P-polarized light.
According to the projector 700 having such a configuration, since the image light L ′ that is linearly polarized light can be emitted, the polarization control element 800 as in the first embodiment described above becomes unnecessary, and the configuration of the image display system 100. Is simplified.

The ninth embodiment as described above can achieve the same effects as those of the first embodiment described above.
In the present embodiment, the single-plate system using one reflective liquid crystal panel 740 is used, but the configuration of the projector 700 is not limited to this. For example, a three-plate system in which a reflective liquid crystal panel is provided for each of red light, green light, and blue light, or a configuration using a transmissive liquid crystal panel instead of the reflective liquid crystal panel may be used. In addition, a projector in which each color light from the light source unit 710 is linearly polarized in advance having only vibration components in the same direction (for example, a polarization control type single-plate projector, a scan in which the polarization direction of each color light is controlled) If it is a projector etc., it will not specifically limit as a structure of a projector.

As described above, the image display system of the present invention has been described based on the illustrated embodiment. However, the image display system of the present invention is not limited to this, and the configuration of each unit is an arbitrary one having the same function. It can be replaced with that of the configuration. Moreover, you may combine each embodiment.
In the above-described embodiment, the reverse type screen is used. However, a normal type screen, that is, a screen that is in a scattering state in a voltage non-application state and in a transmission state in a voltage application state may be used.

  DESCRIPTION OF SYMBOLS 100 ... Image display system 200, 200A, 200B, 200C, 200D, 200F ... Screen 211, 212 ... Transparent substrate 221, 222 ... Electrode 231, 232 ... Alignment film 240 ... Lambda / 4 phase difference plate 250, 250B, 250F ... High Molecular dispersion type liquid crystal layer 251,251B ... PDLC 252,252B ... polymer 253,253B ... liquid crystal molecule 260 ... reflection layer 300 ... projector 310 ... illumination optical system 311 ... light source 312 ... reflector 313 ... lens array 314 ... lens array 315 ... Polarization conversion element 316 ... Superimposing lens 320 ... Color separation optical system 321 ... B light reflecting dichroic mirror 322 ... RG light reflecting dichroic mirror 323 ... G light reflecting dichroic mirror 324 ... Reflecting mirror 325 ... Reflecting mirror 3 30B ... Parallelizing lens 330G ... Parallelizing lens 330R ... Parallelizing lens 340B ... Spatial light modulator 340G ... Spatial light modulator 340R ... Spatial light modulator 350 ... Cross dichroic prism 350B ... Incident surface 350G ... Incident surface 350R ... Incident surface 351: Dielectric multilayer film 352: Dielectric multilayer film 360: Projection optical system 361 ... Reflection mirror 362 ... Reflection mirror 363 ... Reflection mirror 370 ... Polarization rotator 400 ... Control unit 410 ... Image signal processing unit 420 ... Screen control unit 500 ... Personal computer 600 ... Projector 620 ... Light source device 621 ... Super high pressure mercury lamp 622 ... Reflector 630 ... Uniform illumination optical system 631 ... Rod integrator 632 ... Color wheel 632a ... Filter surface 6 33 ... Relay lens group 634 ... Reflection mirror 640 ... Spatial light modulation device 641 ... Substrate 642 ... Light modulation element 650 ... Projection optical system 651 ... Projection lens 700 ... Projector 710 ... Light source unit 711B, 711G, 711R ... Laser light source 712B, 712G 712R ... Collimator lenses 713B, 713G, 713R ... Dichroic mirror 730 ... PBS prism 740 ... Reflective liquid crystal panel 750 ... Projection optical system 800 ... Polarization control element 900 ... Light projection device I, I '... Image signal L1, L2 ... Linearly polarized light L, L ', L "... Video light S ... Display area

Claims (12)

A first alignment film, a second alignment film disposed opposite to the first alignment film, a polymer sandwiched between the first alignment film and the second alignment film, and comprising a liquid crystal molecule and a polymer different from the liquid crystal molecule A dispersion type liquid crystal layer, a phase difference layer that gives a phase difference of ¼ wavelength to light located on the opposite side of the polymer alignment type liquid crystal layer of the second alignment film, and the second alignment film of the phase difference layer; A screen located on the opposite side and having a reflective layer having light reflectivity, and capable of switching between a scattering state in which light is scattered and a transmission state in which light is transmitted through the polymer liquid crystal layer;
An optical projection device that projects linearly polarized light that vibrates in a first direction on the screen from the first alignment film side of the screen and displays an image on the screen;
The first alignment layer is rubbed in a direction perpendicular to the first direction;
A twist angle of the liquid crystal molecules is 90 ° × n (where n is an integer of 0 or more).   The image display system according to claim 1, wherein a twist angle of the liquid crystal molecules is 0 °.   The image display system according to claim 1, wherein the polymer dispersed liquid crystal layer is a twisted nematic type.   The image display system according to claim 1, wherein the polymer dispersed liquid crystal layer is a vertical alignment type.   The polymer dispersed liquid crystal layer is divided into a plurality of display areas, and the scattering state and the transmission state can be switched independently for each of the plurality of display areas. The image display system according to one item.   The image display system according to claim 1, wherein the reflective layer can switch between a reflective state in which light is reflected and a transmissive state in which light is transmitted. The light projection device includes a light source,
A spatial light modulator that modulates the intensity of light emitted from the light source to generate image light;
A projection optical system that projects the image light generated by the spatial light modulator toward the screen;
The image display system according to claim 1, further comprising: a polarization control element that linearly polarizes the image light generated by the spatial light modulation device.   The image display system according to claim 7, wherein the polarization control element is located on an optical axis between the spatial light modulation device and the projection optical system.   The image display system according to claim 7, wherein the polarization control element is located on an optical axis between the projection optical system and the screen. The light projection device includes illumination optical systems that emit red light, green light, and blue light that are linearly polarized light, and
A first spatial light modulator that modulates the red light;
A second spatial light modulator for modulating the green light;
A third spatial light modulator that modulates the blue light;
One or two of the red light modulated by the first spatial light modulator, the green light modulated by the second spatial light modulator, and the blue light modulated by the third spatial light modulator The image display according to claim 1, further comprising: a polarization rotator that rotates polarization directions of the two lights to align the polarization directions of the red light, the green light, and the blue light. system.   The image display system according to claim 10, wherein the polarization rotator aligns the polarization directions of the red light, the green light, and the blue light by rotating a polarization direction of at least one of the red light and the blue light. The light projection device includes an illumination optical system that sequentially emits red light, green light, and blue light, which are linearly polarized light that vibrates in the same direction;
The image display system according to claim 1, further comprising: a spatial light modulation device that modulates the red light, the green light, and the blue light.

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