JP2000147428A - Projection type image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize the whole of devices even while realizing a large screen in a back projection type image display device. SOLUTION: This projection type display device is provided with an image display device 102, a projection lens 103, a transmission type screen 108 and it is provided with a first reflection surface 105 being a circularly polarized light selecting means existing at a position that interrupts incident lights to the screen 108 and a second reflection surface 106 being a linearly polarized selecting means existing between the first reflection surface 105 and the projection lens 103 and, moreover, a quater-wave plate 107 is provided between the first reflection surface 105 and the second reflection surface 106.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type image display apparatus for obtaining an enlarged image by optically enlarging an image on the image display apparatus.

[0002]

2. Description of the Related Art Projection type image display devices can be broadly classified into front projection type and rear projection type. Since the former is easy to carry and the cost is relatively low compared to the rear type, data-compatible models for displaying images on liquid crystal mainly for presentation purposes have established a large market and are expanding. On the other hand, the latter market is mainly of a type in which images are displayed by using a CRT and can be configured more advantageously than a liquid crystal type, so that a market is formed mainly for video images in a consumer market. The market is growing, but only slightly.

[0003] On the other hand, in the broadcasting form, it can be assumed that the image quality, the number of channels, and the multimedia are rapidly increasing due to the transition from the conventional analog to the digitalization. It is thought that the need for the conversion will increase.

An improvement required for the conventional rear projection type image display apparatus is downsizing of the apparatus other than the screen.

FIG. 8 shows the configuration of a conventional rear projection type image display device. It mainly consists of a projection device, a folding mirror, and a transmission screen. Projection devices with a projection lens arranged on the front of the CRT are prepared for each of blue, green, and red, and images are synthesized on the transmission screen via the folding mirror. It is carried out. In recent years, a device that uses a liquid crystal for the projection device, combines blue, green, and red images in the projection device and projects the image with a single projection lens has been commercialized. In the configuration of FIG. 8, the depth is large and the installation position is limited.

[0006] In addition to the miniaturization of the device described above, there is a problem of cost. As described above, as high-quality broadcasting starts, the image display device is required to have higher resolution. However, in the field of large-sized images, it is difficult to achieve both resolution and brightness with a conventional CRT, and it is difficult to guarantee focus to the periphery. Therefore, an image display apparatus using a fixed display device as a light valve has a performance problem. desirable. However, the light valve system that uses liquid crystal, which is currently the mainstream, requires a light source, a color separation optical system, a liquid crystal panel, a color synthesis optical system, and a projection lens as its basic configuration, making cost reduction difficult. Even in a configuration using a small high-temperature polysilicon liquid crystal panel, it is necessary to dispose the panel for each optical path of each color, which occupies a large part of the set cost.

[0007] On the other hand, there is a liquid crystal panel which has a single liquid crystal panel and supports color. However, as in the case of the three-panel type, the resolution (for example, 720P, 108
Considering the realization of 0i), no reasonable solution can be obtained.

[0008]

To cope with the problem of making the device thinner, Japanese Patent Application Laid-Open No. 7-219047 attempts to make the device thinner by using the entrance surface of a transmission screen as a reflection means. Japanese Patent Application Laid-Open No. H8-339033 describes that a portion using linearly polarized light is replaced by circularly polarized light in Japanese Patent Application Laid-Open No. 7-219047, which describes a technique for solving the same problem. .

It has been suggested that the depth of the device can be reduced by such an improvement method. However, in any case, the projection optical system and a part for accommodating the image display device are required at the lower part (one example) of the screen as viewed from the observer, so that it is necessary to raise the position of the screen. Therefore, the arrangement of the apparatuses is apt to be limited to the floor-standing type.

A first problem to be solved by the present invention is to improve the degree of freedom in setting a set such as placing it on a desk by reducing or eliminating the chin of the apparatus while reducing the thickness.

A second problem to be solved by the present invention is as follows.
The goal is to achieve a configuration that can achieve an acceptable price in the consumer market while supporting high resolution.

[0012]

In order to solve the problems of thinning the set and shortening the chin, the rear projection type image display device according to the first invention displays an image in accordance with an input signal. A device, a projection lens for enlarging and projecting an image on the image display device, and a transmission screen provided to project an image projected through the projection lens,
A first reflection unit and a second reflection unit on an optical path between the projection lens and the screen, wherein the first reflection unit is near the incident surface side of the transmission screen. A second reflection member which is disposed at a position where light incident on the transmission screen is blocked, transmits light having a certain circular polarization direction, and reflects light having a circular polarization direction which is opposite to the circular polarization direction. The means is disposed at a position blocking the optical axis between the first reflecting means and the projection lens, and transmits light in a certain linear polarization direction and reflects light in a linear polarization direction orthogonal to the linear polarization direction. And a first optical means for converting linearly polarized light to circularly polarized light and for converting circularly polarized light to linearly polarized light is provided between the first reflecting means and the second reflecting means. It is configured as a feature.

[0013] Here, it is also possible to provide a polarization component removing means for removing the polarized component light in the direction reflected by the second reflecting means between the image display device and the second reflecting means. Specifically, an absorption type polarizing plate can easily cope with this. It goes without saying that a reflective polarizer can also be used.

Further, the transmission type screen may be provided with optical means for absorbing a circularly polarized light component in a direction reflected by the first reflection means. Specifically, it can be easily configured by combining a λ / 4 plate and an absorption type polarizing plate.

Further, the first reflecting means can be provided with a cholesteric liquid crystal layer. Cholesteric liquid crystals are available from S.I.D. 94 Digest ("SID 9
It is apparent that the desired performance can be obtained by disposing the cholesteric liquid crystal layer as described in “4DIGEST”, p. Already, a cholesteric film has been introduced to the market as a method for improving the light utilization of a direct-view LCD monitor.

[0016] The second reflection means can be provided with a reflection type polarizing plate. As the reflective polarizing plate, a double brightness enhancement film (DBEF) can be used.

In the first aspect of the present invention described above, the image display device is constituted by using a liquid crystal light valve which displays an image by utilizing polarized light and modulating incident light by an external control signal. It can be configured as a feature. This is a desirable configuration for an image display device because there is no loss of brightness even in the case of limiting the polarization as in the present case, and it goes without saying that the present invention can be applied to a transmission device and a reflection device.

According to the first aspect of the present invention, a λ / 4 plate is provided as an optical means for converting linearly polarized light into circularly polarized light and converting circularly polarized light into linearly polarized light.

Next, a configuration for solving the problem of cost reduction of the device will be described hereinafter. A projection type image display device according to a second aspect of the present invention includes an image display device for displaying an image in accordance with an input signal, a light source having a small light emitting unit, an illumination optical system for enlarging and projecting the light source image on a screen, and a screen. The image display device is disposed between the illumination optical system and the screen in parallel with the screen, a distance from the screen to the image display device is L1, and the illumination from the image display device is When the distance to the exit pupil of the optical system is L2, the relationship L1 <L2 can be established.

Therefore, when the pixel pitch of the display image on the screen is P and the size of the exit pupil of the illumination optical system in the pitch direction is D, it is desirable that the relationship of P / L1> D / L2 is satisfied. .

Further, the image display device can be constituted by providing optical means for improving distortion occurring in an image on the screen in the vicinity of the image display device or between the image display device and the screen. Specifically, it is an aberration correction unit using an aspherical optical system such as a Schmidt correction plate.

Here, the screen can be configured as a rear projection type by being a transmission type screen.

Further, an optical system having a convex lens function is provided near the entrance side of the image display device, and an optical system having a concave lens function is provided near the exit side of the image display device. If it can be formed, it can be configured without sacrificing the set size.

[0024] A folding mirror is provided between the image display device and the illumination optical system.
Set depth dimension can be shortened.

Similarly, as a technique for shortening the set depth dimension, in the second invention, in the vicinity of the incident surface of the image display device, incident light in a certain polarization direction is transmitted and light in a polarization direction orthogonal to this is reflected. A first reflection unit provided at a position for blocking light incident on the image display device;
A second reflecting means arranged to reflect the light reflected by the reflecting means and to enter the image display device, wherein a linearly polarized light is circularly polarized between the first reflecting means and the second reflecting means. And optical means for converting circularly polarized light into linearly polarized light. Here, the first reflecting means can be constituted by including a reflective polarizing plate, and the second reflecting means can be constituted by a total reflection mirror.

As a technique for further reducing the set depth dimension, in the second invention, in the vicinity of the incident surface of the image display device, incident light in a certain circularly polarized light direction is transmitted, and light in a circularly polarized light direction reverse to the above is reflected. A first reflecting means for blocking the light incident on the image display device, and the incident light in a linear polarization direction at a position for blocking an optical path between the first reflecting means and the illumination optical system. There is provided a second reflecting means for transmitting and reflecting light in a direction of linear polarization orthogonal to the light, and converts linearly polarized light into circularly polarized light between the first reflecting means and the second reflecting means. And an optical means for converting circularly polarized light into linearly polarized light. Here, the first reflecting means can be configured to include a cholesteric liquid crystal layer, and the second reflecting means can be configured to include a reflective polarizing plate.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the first aspect of the present invention, linearly polarized light and circularly polarized light are transmitted and reflected, respectively, to thereby provide two reflecting means between the image display device and the screen, but to provide effective means for each. Since it can be placed at a position that blocks the area, it is possible to make the device thinner and at the same time greatly reduce or eliminate the portion under the chin under the screen, greatly improving the freedom of installation compared to the conventional rear projection type image display device it can.

According to the second aspect of the present invention, a complicated optical system becomes unnecessary, and if a large-format liquid crystal panel, which is widely used for a notebook computer or a monitor of a personal computer, is used as an image display device, both low cost and high resolution can be achieved. Can be done. However, it is desirable that the light source be a small-area light emitter close to a point light source.

(Embodiment 1) FIG. 1 is a schematic configuration diagram of a display device of Embodiment 1 which is an example of a projection type image display device of the present invention.

Light source 101, image display device 102, projection lens 103, folding mirror 104, circularly polarized light selection surface 1
05, a linear polarization selection surface 106, a λ / 4 plate 107, and a transmission screen 108. The light source unit 101 includes a light source 109 that forms an arc by discharge between the electrodes to generate randomly polarized light, and a reflector 110 that reflects light from the light source 109 in one direction on a rotationally symmetric axis. Light from the light source 101 reaches the image display device 102. This image display device 102 is composed of a liquid crystal panel sandwiched between an incident side polarizing plate and an outgoing side polarizing plate.

The direction of polarization of the incident light is defined in advance by the incident-side polarizing plate, and the light transmitted therethrough and incident on the liquid crystal panel is incident on the effective opening of the liquid crystal panel. The polarization direction can be changed independently.
These lights are transmitted and absorbed by the exit-side polarizing plate, and the light of each pixel is adjusted by absorption, and the projection lens 10 serving as a projection optical system.
3 is incident. The light thus projected by the projection lens 103 is reflected by the turning mirror 104 and enters the linearly polarized light selection surface 106. At this time, the output side polarizing plate is set so that the light from the projection lens is polarized in the vibration direction in the same direction as the polarization direction transmitted by the linear polarization selection surface 106, so that the linear polarization selection surface 106 is affected. And enters the circularly polarized light selection surface 105 via the λ / 4 plate 107. As shown in the figure, since the phase axis of the λ / 4 plate 107 is provided at an angle of about 45 degrees with the vibration direction of the incident polarized light, it is converted into circularly polarized light. Incident.

The circularly polarized light selection surface 105 has a characteristic of reflecting an arbitrary circularly polarized light and transmitting a circularly polarized light of reverse rotation.
Since the direction of circular polarization of the incident light is set to be the direction of reflection, the light incident on the circularly polarized light selection surface 105 is reflected here, becomes a circularly polarized light of reverse rotation, and becomes λ again.
Incident on the / 4 plate 107. The light transmitted through the λ / 4 plate 107 is converted into linearly polarized light in a direction orthogonal to the polarization direction that has entered through the linearly polarized light selection surface 106 at first, and is reflected by the linearly polarized light selection surface 106. This light is again incident on the λ / 4 plate 107, but initially the linearly polarized light selection surface 106
Is converted into circularly polarized light in the same direction as the direction of polarization orthogonal to the direction of polarization incident through the Therefore, the light passes through the circularly polarized light selection surface 105 and reaches the screen 108. Thus, the image on the image display device can be enlarged and projected on the screen 108.

As described above, when the image display device is a light valve that modulates incident light using polarized light, the projection distance can be obtained by reflection inside the device without loss of light. Periodically, it can be made small.

The folding mirror 104 is not always necessary, and can be dealt with by a means such as bending in a projection lens or a projection device.

Although the λ / 4 plate 107 is shown independently, a linearly polarized light selecting surface 106 or a circularly polarized light selecting surface 105 is shown.
Needless to say, it can be integrally formed by laminating on a sheet.

Here, the linearly polarized light selection surface 106 or the circularly polarized light selection surface 105 is arranged obliquely with respect to the screen 108, but can be constructed in the same manner even if it is parallel as shown in FIG. At this time, since the circularly polarized light selection surface 105 and the screen 108 can be integrated or arranged close to each other, the device can be configured to be smaller.

Although the image display device can be constructed without applying polarized light, it is possible to suppress the generation of stray light and the like by setting it in one polarization direction with an absorption-side polarizing plate or the like before entering the linear polarization selection surface 106. I can do it. This linearly polarized light selection surface 10
The pre-polarized light before being incident on 6 may be used in combination with an image display device using polarized light.

If the screen 108 is provided with a λ / 4 plate and an absorbing polarizer to absorb only the circularly polarized light in the direction which is originally reflected by the circularly polarized light selection surface 105, the light selection of the circularly polarized light selection surface 105 can be achieved. Is not sufficient, and even if unnecessary light leaks into the screen side, it does not become harmful light of the displayed image, which is desirable.

The circularly polarized light selection surface 105 can be constituted by providing a cholesteric liquid crystal layer on a substrate. However, it goes without saying that the present invention is satisfied if the same operation is performed regardless of the cholesteric liquid crystal layer. The linearly polarized light selection surface 106 is considered to be a feasible configuration in which a sheet-shaped reflection-type polarizing plate is bonded to a substrate, but is not limited to this, and is an element capable of realizing the same operation. Needless to say, it is applicable if it exists.

(Embodiment 2) FIG. 3 is a schematic configuration diagram of Embodiment 2.

A light source unit 201, an illumination optical system 202, an image display device 203, and a screen 204 are provided. Light source 2
01 is a light source 205 which forms an arc by electric discharge between the electrodes to generate randomly polarized light, a reflector 206 having an elliptical reflecting means for reflecting the light from the light source 205 in one direction on its rotational symmetry axis, It consists of a rod integrator 207 arranged on the front. The light emission surface of the rod integrator 207 is configured as a pseudo light emission surface, and the illumination optical system 202 including a plurality of lenses is configured to enlarge and project the pseudo light emission surface image on a screen 204 disposed on the front surface.

The illumination optical system 202 and the screen 204
An image display device 203 is disposed in parallel with the screen 204. This image display device 203 is composed of a liquid crystal panel sandwiched between an incident side polarizing plate and an emitting side polarizing plate. The direction of polarization of the incident light is limited in advance by the incident side polarizing plate, and the light transmitted through this and incident on the liquid crystal panel is incident on the effective opening of the liquid crystal panel. Can be changed independently. These lights are transmitted and absorbed by the exit-side polarizing plate, and the light of each of the pixels is adjusted by the absorption. At this time, the distance from the image display device 203 to the screen 204 is L
1. When the distance from the illumination optical system 202 to the image display device 203 is L2, the image display device 2 is set to L1 <L2.
An image with less blur is provided by suppressing the spread of light incident on the light-receiving element 03.

Thus, according to the present invention, an expensive projection optical system or the like is not required, and a color image can be easily obtained if the liquid crystal panel has a built-in color filter.

Further, by using a liquid crystal panel that is proposed in the market for a notebook computer or a monitor, high resolution can be realized at low cost.

In FIG. 3, when the pixel pitch of the display image on the screen 204 is P and the size of the exit pupil of the illumination optical system 202 in the pitch direction is D, P / L
If the relationship of 1> D / L2 holds, the pixel centers on the liquid crystal panel do not overlap. Therefore, it can be used at least for applications such as data display.

As shown in FIG. 4, the device can be miniaturized by disposing the folding mirror 208 between the illumination optical system 202 and the image display device 203. Furthermore, here, the screen 20
A correction plate 209 for correcting the pincushion-shaped distortion generated in the image on No. 4 is disposed near the image display device 203. Thus, a good image can be obtained even if the magnification of the image of the image display device 203 is increased.

As described above, the image display device 203
When a liquid crystal panel is used, the incident angle of the incident light may be different depending on the specification, but by setting the incident angle to approximately 0 degrees, it is easy to secure the contrast. Therefore, as shown in FIG. 5, a Fresnel lens 210 as an optical unit having a condensing function (convex lens effect) is provided on the incident side of the image display device 203, and a Fresnel lens as an optical unit having a diverging function (concave lens effect) is provided on the exit side. If a telecentric optical system is realized by arranging the 211, an image with good uniformity can be obtained.

Although the light source is a discharge lamp and an integrator, it is apparent that the same effect can be obtained by replacing the discharge lamp with a surface light source.

(Embodiment 3) FIG. 6 is a schematic configuration diagram of Embodiment 3.

A light source 301, an illumination optical system 302, a reflective polarizer 303 as a linearly polarized light selection surface, a λ / 4 plate 304,
Folding mirrors 305 and 306, an image display device 307,
And a screen 308. The light source unit 301 includes a light source 309 that forms an arc by electric discharge between the electrodes to generate random polarized light, and a reflector 3 that has an elliptical reflector 3 that reflects light from the light source 309 in one direction on its rotationally symmetric axis.
10 and a rod integrator 311 arranged on the front surface of the reflector. The light emitting surface of the rod integrator 311 is used as a pseudo light emitting surface, and the illumination optical system 302 including a plurality of lenses is configured to enlarge and project the pseudo light emitting surface image on a screen 308 arranged on the front surface.

The illumination optical system 302 and the screen 308
An image display device 307 is disposed in parallel with the screen 308. This image display device 307 is composed of a liquid crystal panel sandwiched between an incident side polarizing plate and an emitting side polarizing plate. The direction of polarization of the incident light is limited in advance by the incident side polarizing plate, and the light transmitted through this and incident on the liquid crystal panel is incident on the effective opening of the liquid crystal panel. Can be changed independently. These lights are transmitted and absorbed by the output-side polarizing plate, and the light of each pixel is adjusted by the absorption. At this time, the distance from the illumination optical system 307 to the image display device 307 is larger than the distance from the image display device 307 to the screen 308, and the image display device 307 is arranged.
Provide an image with less blur by suppressing the spread of light incident on the.

The light emitted from the illumination optical system 302 is reflected by a reflection mirror 305, and is reflected by a reflection type polarizer 303 provided on the incident side of the image display device 307.
Incident on. The reflection type polarizing plate 303 has a light selectivity that reflects a certain linearly polarized light and transmits a linearly polarized light orthogonal to the linearly polarized light. Therefore, of the light incident here, the reflected light is λ / 4. After being incident on the plate 304, it is converted into circularly polarized light, and then enters the turning mirror 306 and is reflected. As it is reflected by circularly polarized light, the direction of circularly polarized light is reversed,
After passing through the λ / 4 plate 304 again, the λ / 4 plate 304
Is a linearly polarized light orthogonal to the polarization direction of the light incident on the.
Therefore, this light passes through the reflective polarizing plate 303 and reaches the image display device 307. At this time, the polarization direction incident on the image display device 307 is configured to match the polarization direction transmitted by the incident-side polarization plate of the liquid crystal panel.

As described above, according to the present embodiment, it is possible to reduce the size of the entire device while maintaining the effects of the second embodiment. However, in the above configuration, the available polarization direction of the light from the light source is limited, so that the brightness of the second embodiment is reduced by half. If this is a practical problem, the polarization direction is separated, and one of the polarized lights is subjected to polarization conversion by a phase difference plate, and an optical system for preliminarily aligning the polarization direction of the light from the light source before entering the reflective polarizing plate 303. It can be improved if it is provided in the above.

If the light from the light source is light having a uniform polarization direction in advance, it is needless to say that brightness equivalent to that of the second embodiment can be obtained.

(Embodiment 4) FIG. 7 is a schematic configuration diagram of Embodiment 3.

The light source unit 401, the illumination optical system 402, the folding mirror 403, the reflection type polarizer 404 corresponding to the linearly polarized light as the linearly polarized light selection surface, the λ / 4 plate 405, the cholesteric film surface 406 as the circularly polarized light selection surface, the image Display device 4
07, a distortion aberration correction plate 408, and a screen 409.

The light source unit 401 includes a light source 410 that forms an arc by electric discharge between the electrodes to generate randomly polarized light, and a reflector that reflects light from the light source 410 in one direction on a rotationally symmetric axis thereof. 411, a rod integrator 41 arranged on the front surface of the reflector
Consists of two. Illumination optical system 40 composed of a plurality of lenses using the emission surface of rod integrator 412 as a pseudo emission surface
A screen 4 in which the pseudo luminous surface image is arranged on the front in 2
09 is enlarged and projected.

The illumination optical system 402 and the screen 409
An image display device 407 is arranged between the screens 409 in parallel. This image display device 407 is composed of a liquid crystal panel sandwiched between an incident side polarizing plate and an emitting side polarizing plate. The direction of polarization of the incident light is limited in advance by the incident side polarizing plate, and the light transmitted through this and incident on the liquid crystal panel is incident on the effective opening of the liquid crystal panel. Can be changed independently. These lights are transmitted and absorbed by the emission-side polarizing plate, and the light of each pixel is adjusted by the absorption, and passes through the light to reach the screen 409.

At this time, the distance from the illumination optical system 402 to the image display device 407 is set to be larger than the distance from the image display device 407 to the screen 409, and the spread of light incident on the image display device 407 is reduced. Providing images with less blur by suppressing them. Furthermore, pincushion-like distortion generated in a projected image is corrected by transmitting the light through a correction plate 408 disposed near the image display device 407 from the image display device 407 to the screen 409.

The light emitted from the illumination optical system 402 is reflected by a folding mirror 403 and enters a reflective polarizer 404 corresponding to linearly polarized light, whereby certain polarized light is reflected and removed. Is transmitted through the reflective polarizer 404 corresponding to linearly polarized light and then transmitted through the λ / 4 plate 405 to become circularly polarized light. Since the circular polarization direction at this time is the direction reflected by the cholesteric film surface 406 which is the circular polarization selection surface, the light is reflected here, the circular polarization direction is reversed, and the λ / 4 plate 405 is returned again.
Incident on. As a result, the circularly polarized light is initially λ / 4 plate 405
The reflected light becomes a polarized light in a direction orthogonal to the linearly polarized light incident on the reflective polarizer 404 corresponding to the linearly polarized light. The light incident on the mirror 403 and transmitted therethrough is orthogonal to the polarization direction, so that the light is reflected here, and is again reflected by the λ / 4 plate 4.
05 and becomes circularly polarized light. At this time, the direction of the circularly polarized light is initially the cholesteric film surface 40 which is the circularly polarized light selection surface.
6 is reversed from that when it is incident on the image display device 6 and reaches the image display device 407.

A λ / 4 plate 410 is arranged between the cholesteric film surface 406 and the image display device 407, and is configured to convert circularly polarized light into linearly polarized light and enter the image display device 407. The direction of polarization at this time is set to be the same as the direction of polarization transmitted through the incident-side polarizing plate of the image display device 407.

As described above, according to the present embodiment, the whole device can be formed more compact while the effect of (Embodiment 2) is maintained as in (Embodiment 3). However, even in the above configuration, the available polarization direction of the light from the light source is limited, so that the brightness of the second embodiment is reduced by half. If this is a practical problem, the reflection type polarizing plate 404 is used to separate the polarization directions and convert one of the polarized lights into polarized light with a retardation plate to pre-align the polarization directions of the light from the light source.
It can be improved if it is provided until it is incident on the surface. If the light from the light source has a uniform polarization direction in advance, it is needless to say that brightness equivalent to that of the second embodiment can be obtained.

In the configuration diagrams of the embodiments described above, the image display device is a single-panel type picture composed of one liquid crystal panel. However, the present invention is not limited to this and is not limited to the current market. It goes without saying that the mainstream three-plate type configuration can also be applied.

[0064]

As described above, according to the projection type image display apparatus of the present invention, according to the first aspect of the present invention, while keeping the projection distance of the projection lens, the thickness of the apparatus is reduced and the portion under the chin under the screen is greatly reduced. Alternatively, it can be eliminated, and the degree of freedom in installation can be greatly improved as compared with the conventional rear projection type image display device.

Further, according to the second aspect of the present invention, a complicated optical system is not required, which is advantageous in terms of optical component cost and assembly cost. In addition, it is possible to achieve both low cost and high resolution by using a large-sized liquid crystal panel. Therefore, it is possible to provide a low-priced product with high resolution.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration example of a projection image display apparatus according to a first embodiment of the present invention;

FIG. 2 is a diagram showing an application configuration example of the display device.

FIG. 3 is a diagram showing a configuration example of a projection type image display device according to a second embodiment of the present invention;

FIG. 4 is a diagram showing an example of an application configuration of the display device.

FIG. 5 is a diagram showing another application configuration example of the display device.

FIG. 6 is a diagram illustrating a configuration example of a projection-type image display device according to a third embodiment of the present invention;

FIG. 7 is a diagram showing a configuration example of a projection-type image display device according to a fourth embodiment of the present invention;

FIG. 8 is a schematic basic configuration diagram of a conventional projection type image display device.

[Explanation of symbols]

101, 201, 301, 401 Light source unit 102, 203, 307, 407 Image display device 103 Projection lens 104, 208, 305, 306, 403 Folding mirror 105, 406 Circular polarization selection surface 106, 303, 404 Linear polarization selection surface 107 , 304, 405 λ / 4 plate 108 Transmission screen 109, 205, 309, 410 Light source 110, 206, 310, 411 Reflector 207, 311, 412 Rod integrator 209, 408 Correction plate 210, 211 Fresnel lens 302 Illumination optical system 204 , 308, 409 screen

Claims (17)

[Claims] 1. An image display device for displaying an image in accordance with an input signal, a projection lens for enlarging and projecting an image on the image display device, and an image display device for projecting an image projected via the projection lens. And a first reflection means and a second reflection means on an optical path between the projection lens and the transmission screen, wherein the first reflection means is one of the two reflection means. Is disposed at a position near the incident surface side of the transmission screen to block light incident on the transmission screen, transmits light in a certain circular polarization direction, and transmits light in a circular polarization direction opposite to the circular polarization direction. The second reflecting means is provided at a position blocking an optical axis between the first reflecting means and the projection lens, transmits light in a certain linear polarization direction, and is orthogonal to the linear polarization direction. Reflect light in the direction of linear polarization A first optical unit having a characteristic and converting linearly polarized light into circularly polarized light and converting circularly polarized light into linearly polarized light is provided between the first reflecting unit and the second reflecting unit; A projection type image display device characterized by the above-mentioned. 2. A device according to claim 1, further comprising a polarization component removing unit between the image display device and the second reflection unit for removing light of a polarization component in a direction reflected by the second reflection unit. The projection type image display device according to claim 1. 3. The projection type image display according to claim 1, wherein the transmission type screen is provided with second optical means for absorbing a circularly polarized light component in a direction reflected by the first reflection means. apparatus. 4. The projection type image display device according to claim 1, wherein the first reflection means includes a cholesteric liquid crystal layer. 5. The projection type image display device according to claim 1, wherein the second reflection means includes a reflection type polarizing plate for linearly polarized light. 6. The projection type image display device according to claim 1, wherein the image display device includes a liquid crystal light valve for displaying an image by modulating incident light by an external control signal. 7. An image display device for displaying an image in response to an input signal, a light source having a light emitting unit, illumination optical means for enlarging and projecting the light source image, and displaying a light source image output from the illumination optical means. The image display device is disposed between the illumination optical means and the screen in parallel with the screen, a distance from the screen to the image display device is L1, and the image display device is illuminated from the image display device. If the distance to the exit pupil of the optical means is L2, L1
<A projection-type image display device characterized by having a relationship of L2. 8. When the pixel pitch of a display image on a screen is P and the size of an exit pupil of the illumination optical means in the pitch direction is D, the relationship of P / L1> D / L2 is satisfied. The projection type image display device according to claim 7, wherein 9. The apparatus according to claim 7, further comprising third optical means for improving distortion occurring in an image on said screen in the vicinity of said image display device or between said image display device and said screen. Projection image display device. 10. The projection type image display device according to claim 7, wherein the screen is a transmission type screen. 11. A fourth optical means having a convex lens function near the entrance side of the image display device, and a fifth optical means having a concave lens function near the emission side of the image display device. The projection type image display device according to claim 7, wherein 12. A folding mirror is provided between the image display device and the illumination optical means.
The projection type image display device according to the above. 13. Near the entrance surface of the image display device, a third reflection unit that transmits incident light in a certain polarization direction and reflects light in a polarization direction orthogonal to the incident light is incident on the image display device. And a fourth reflecting means arranged to reflect the light reflected by the third reflecting means and to enter the image display device, wherein the third reflecting means and the third reflecting means are provided. 8. The projection type image display apparatus according to claim 7, further comprising sixth optical means for converting linearly polarized light to circularly polarized light and for converting circularly polarized light to linearly polarized light between the reflecting means. 14. The projection type image display device according to claim 13, wherein said third reflection means is provided with a reflection type polarizing plate. 15. The projection type image display device according to claim 13, wherein the fourth reflection means is a total reflection mirror. 16. Near the entrance surface of the image display device, fifth reflecting means for transmitting incident light in a certain circular polarization direction and reflecting light in a circular polarization direction which is opposite to the incident light enters the image display device. At a position where the optical path between the fifth reflection means and the illumination light means is blocked, and transmits light having a certain linear polarization direction at a position where the optical path between the fifth reflection means and the illuminating light means is blocked. And a sixth reflecting means for converting linearly polarized light into circularly polarized light and converting circularly polarized light into linearly polarized light between the fifth reflecting means and the sixth reflecting means. 8. The projection type image display device according to claim 7, further comprising: an optical unit. 17. The projection type image display device according to claim 16, wherein the fifth reflecting means includes a cholesteric liquid crystal layer, and the sixth reflecting means includes a reflective polarizing plate.