Image display device Number:7,044,607 from the United States Patent and Trademark Office (PTO) owispatent An image display device has three reflective image display elements for red, green and blue to form an optical image according to a video signal from light output from a light source, and an optical system to supply light onto the display elements and to combine and output the light reflected from the display elements. The image display device includes a first polarity converting unit to convert luminous flux from the light source to S polarized light, a first polarized beam splitter, and second polarized beam splitter. The reflective image display element for green is provided in a vicinity of the first polarized beam splitter, and the light reflected by the first polarized beam splitter and input to the reflective image display element for green is S polarized light. The light output from the reflective image display element for green permeates the first and second polarized beam splitters.<H display, device, Image, display, d, 7044607.html, Patent, pto, 7044607

Title: Image display device

Abstract: An image display device has three reflective image display elements for red, green and blue to form an optical image according to a video signal from light output from a light source, and an optical system to supply light onto the display elements and to combine and output the light reflected from the display elements. The image display device includes a first polarity converting unit to convert luminous flux from the light source to S polarized light, a first polarized beam splitter, and second polarized beam splitter. The reflective image display element for green is provided in a vicinity of the first polarized beam splitter, and the light reflected by the first polarized beam splitter and input to the reflective image display element for green is S polarized light. The light output from the reflective image display element for green permeates the first and second polarized beam splitters.

Patent Number: 7,044,607 Issued on 05/16/2006 to Ouchi, et al.

Inventors: Ouchi; Satoshi (Kamakura, JP); Imahase; Taro (Fujisawa, JP); Miyoshi; Tomohiro (Fujisawa, JP); Abe; Fukuyasu (Yokohama, JP)
Assignee: Hitachi, Ltd. (Tokyo, JP)

Appl. No.: 175177

Filed: July 7, 2005

Related U.S. Patent Documents


Application Number	Filing Date	Patent Number	Issue Date
10638804	Aug., 2003	6926411
09810571	Mar., 2001	6626540

Foreign Application Priority Data


Mar 17, 2000 [JP]			2000-081774

Current U.S. Class: 353/31 ; 349/9; 353/20

Current International Class: G03B 21/14 (20060101)

Field of Search: 353/20,31,33,34,37 349/5,7,8,9

References Cited [Referenced By]

U.S. Patent Documents


5357289	October 1994	Konno
6176586	January 2001	Hirose et al.
6183091	February 2001	Johnson et al.
6247814	June 2001	Lin
6273567	August 2001	Conner et al.
6280034	August 2001	Brennesholtz
6304302	October 2001	Huang et al.
6343864	February 2002	Tajiri
6364488	April 2002	Lin
6375330	April 2002	Mihalakis
6402323	June 2002	Shiue et al.
6460998	October 2002	Watanabe
6550919	April 2003	Heine
6626540	September 2003	Ouchi et al.
6926411	August 2005	Ouchi et al.

Foreign Patent Documents


0 435 288	Jul., 1991	EP
11-326861	Nov., 1999	JP
WO 00/02087	Jan., 2000	WO

Primary Examiner: Dowling; William C.
Attorney, Agent or Firm: Antonelli, Terry, Stout and Kraus, LLP.

Parent Case Text

CROSS REFERENCE TO RELATED APPLICATION

This application is continuation of U.S. Ser. No. 10/638,804 filed Aug. 12, 2003, now U.S. Pat. No. 6,926,411, which is a continuation of application Ser. No. 09/810,571, filed Mar. 19, 2001, now U.S. Pat. No. 6,626,540, the subject matter of which is incorporated by reference herein.

Claims

What is claimed is:

1. An image display device having three reflective image display elements for red, green and blue to form an optical image according to a video signal from light output from a light source, and an optical system to supply the light onto the reflective image display elements and to combine and output the light reflected from the reflective image display elements, comprising: a first polarity converting unit to convert luminous flux from the light source to S polarized light; a first polarized beam splitter; and a second polarized beam splitter; wherein the reflective image display element for green is installed in a vicinity of the first polarized beam splitter; wherein the light reflected by the first polarized beam splitter and input to the reflective image display element for green is S polarized light; wherein green light output from the reflective image display element for green permeates the first polarized beam splitter and the second polarized beam splitter; and wherein one of red light output from the reflective image display element for red and blue light output from the reflective image display element for blue is reflected by the first polarized beam splitter and the other of the red light output and the blue light output is reflected by the second polarized beam splitter.

2. An image display device according to claim 1, wherein the second polarized beam splitter combines the light reflected by the three reflective image display elements.

3. An image display device comprising: a light source unit; three reflective image display elements for red, green and blue to form an optical image according to a video signal from light output from the light source unit; a first polarized beam splitter; and a second polarized beam splitter; wherein the reflective image display element for green is provided in a vicinity of the first polarized beam splitter; wherein the light reflected by the first polarized beam splitter and input to the reflective image display element for green is S polarized light; wherein green light output from the reflective image display element for green permeates the first polarized beam splitter and the second polarized beam splitter; and wherein one of red light output from the reflective image display element for red and blue light output from the reflective image display element for blue is reflected by the first polarized beam splitter and the other of the red light output and the blue light output is reflected by the second polarized beam splitter.

4. An image display device according to claim 3, wherein the second polarized beam splitter combines the light reflected by the three reflective image display elements.

5. An image display device comprising: a light source unit; a red reflective image display element; a blue reflective image display element; a green reflective image display element; a first polarized beam splitter to reflect S-polarized green light toward the green reflective image display element and to transmit green light reflected on the green reflective image display element; a second polarized beam splitter to transmit at least the green light transmitted through the first polarized beam splitter; and a projection lens to project an image on a screen by light output from the second polarized beam splitter; wherein one of red light output from the red reflective image display element and blue light output from the blue reflective image display element is reflected by the first polarized beam splitter and the other of the red light output and the blue light output is reflected by the second polarized beam splitter.

6. An image display device according to claim 5, wherein the second polarized beam splitter combines three lights modulated by each of the red, blue, and green reflective image display elements.

7. An image display device according to claim 5, wherein the green reflective image display element is installed near the first polarized beam splitter.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a display device for projecting images on a screen using light valve elements such as liquid crystal panels or reflective liquid crystal elements and relates in particular for example, to an image display device for liquid crystal projector devices, reflective image display projector devices, liquid crystal televisions and projection type display devices, etc.

2. Description of the Related Art

Projection type display devices such as liquid crystal projectors are known in the related art as a means to irradiate light from a light source such as an incandescent bulb onto light valve elements such as a liquid crystal display panel for projecting an enlarged image.

In image display devices of this type, light from a light source is changed and adjusted for brightness and darkness on each pixel in the light valve element and projected on a screen, etc. In twisted nematic (TN) type liquid crystal display devices constituting typical liquid crystal display elements, two polarizing plates are each installed at mutually different 90 degree light polarization directions, in the front and rear of the liquid crystal cell formed by injecting liquid crystals between a pair of transparent substrates having a transparent electrode film, and by combining the effect from selecting polarized light constituents of the polarizing plate and rotation of the deflection plane by the electro-optical effect of the liquid crystal, the permeable light intensity of the input light is controlled and image information is displayed. In recent years, rapid progress has been made in making these permeable or reflective image display elements themselves more compact and improving performance such as resolution.

The advancements in making display devices using light valve elements such as image display elements more compact and having high performance had led not just simply to making image displays with video signals as in the related art, but proposal of technology for projector type image display devices constituted by image output device for personal computers. Demands here stress compactness and obtaining a bright image extending to all corners of the screen. However, projector type image display devices of the related art have the drawbacks of being large and that the image brightness ultimately obtained and performance characteristics such as image quality are inadequate.

For example when making the overall liquid crystal display device more compact, an effective method is to make the light valve elements or in other words, the liquid crystal display elements themselves smaller. However, when the liquid crystal display elements are made smaller, the surface area irradiated by the liquid crystal means becomes smaller. Consequently, the surface area struck by the lighting means for the total luminous flux intensity emitted by the light source become smaller so the problem occurs that the percentage of luminous flux intensity (hereafter light utilization efficiency) on the liquid crystal element was low to the total luminous flux intensity emitted by the light source. Another problem is that the sides of the screen are dark. Further, the liquid crystal display element can only utilize the polarized light in one direction so that only approximately half of the random polarized light emitted from the light source is utilized. Technology for an optical system to beam random polarized light from a light source on a liquid crystal display element aligned in a one-way polarization direction, is disclosed in Japanese Patent Laid-Open No. H4-63318 wherein a polarity converter element such as a polarized beam splitter is utilized and random polarized light beamed from a light source is separated into P polarized light and S polarized light and combined together using a prism.

The optical system of the related art utilizing the above arrangement, and particularly a lighting system utilizing a reflective liquid crystal display device was configured so that the polarized beam splitter and reflective liquid crystal display element were combined and the light polarization direction converted and checked according to the expressed tones and the on/off of the video, and the video later projected onto a screen by a projecting lens.

Due to the polarized beam splitter, the above configuration had the problems that irregularities occurred in the color and the contrast was low.

In other words, changes occurred in the permeance rate of the P polarized light to the angle of the input light beam and the reflection rate of the S polarized light so that irregularities occurred in the reflection rate and permeance rate of the polarized beam splitter to the specified angle of the lighting system. These irregularities caused deterioration in the quality of the image quality projected on the screen.

The polarized beam splitter such as disclosed in Japanese Patent Laid-Open No. 09-054213 with the permeant material enclosing the PB film was comprised of glass material with an optical resilience coefficient having an absolute value within 1.5.times.10.sup.-8 cm2/N, so that the birefringence (double refraction) was low and the contrast on the screen was improved.

However, in this example of the related art, the weight of the polarized beam splitter glass material itself was heavy (more than twice the conventional weight), the utilization level was preferably low since the cost was high. However, in typical optical systems other than the embodiment of this invention, three R G B reflective panels were used and each required a polarized beam splitter so that no consideration was given to reducing the size, the weight or the cost of the optical system.

Also, in optical systems utilizing reflective liquid crystal display elements, the dichroic mirrors or dichroic prisms made with a dichroic coating and utilized for color separation or combination, changed the direction of the light by means of polarizing the direction of the light when beaming light in a system for color separation and combination. The characteristics are known to change due to the polarization direction of light beamed onto the dichroic coating. In other words, a difference in light wavelength bands occurs in light separated into P polarized light and S polarized light. More specifically, on a dichroic blue reflective surface, the half wavelength of a P polarized light input beam is lower than an S polarized light input beam. In such a case, the beam input with S polarized light is separated into permeable light and reflected light according to the S polarized light half wavelength .lamda. s by the blue reflective coating surface. When the image information is white, the light is converted into P polarized light by the blue reflective liquid crystal display element, and the light beam input again onto the blue reflective coating surface. This time the beam input with P polarized light is separated into permeable light and reflected light according to the polarized light half wavelength .lamda. p. In this case, the half-wavelength portion that has fallen low is not reflected back and is a permeable part of the wavelength band. The light on the permeating part of the wavelength band cannot be utilized in the image display device so the light half-wavelength differential is lost and the brightness diminishes and color performance deteriorates. The same effects occur on the red reflective surface.

Therefore the light that deviates from this wavelength band cannot be utilized. The problem of lowering of the light utilization efficiency and a deteriorated color performance therefore occur in the image display device.

Contrast is an important performance characteristics in image display devices, and inserting a polarizing plate between both or either of the polarized beam splitter and lighting system, and polarized beam splitter and projection lens is effective in improving contrast. However, in the related art, all the red, blue and green light permeates through the polarizing plate creating the problem of a rise in temperature in the polarizing plate, a drop in contrast, and burns on the polarizing plate.

Therefore, as can be seen from the above description, measures must be taken to reduce the size of the optical system and projection image display system itself as well as reduce weight and reduce costs while maintaining the image quality and the brightness of the image display device.

SUMMARY OF THE INVENTION

Methods to reduce the size and weight of the device itself, and lower the cost while maintaining the brightness and image quality performance of the image display device are therefore a problem in the above described technology of the related art. In other words, the optical efficiency of the dichroic prism constituting the color separating/combining means and the polarized beam splitter must be improved, and a method for inputting and outputting light to a reflective panel contrived and respective effective placement contrived in order to improve the image contrast and brightness, reduce the size of the device itself, reduce the weight and lower the cost.

In view of the above problems with the related art, it is an object of the invention to provide image display technology that is compact and inexpensive while maintaining brightness and high image quality.

In order to achieve the above objects, an optical unit of an image display device of this invention is comprised of a reflective image display element for forming an optical image according to a video signal from the light beam output from the light source, and a lighting system to beam the light onto the reflective image display element and synthesize the light reflected from the reflective image display element, wherein the image display device is further comprised of a color separating means to separate the input light into a plurality of light beams, and a color combining means and the color separating means are installed along the optical axis of the light separated from the color separating means.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an overall plan view showing a first embodiment of a projection type liquid crystal image display device of the invention.

FIG. 2 is an overall plan view showing a second embodiment of the projection type liquid crystal image display device of the invention.

FIG. 3 is an overall plan view showing a third embodiment of the projection type liquid crystal image display device of the invention.

FIG. 4 is an overall plan view showing a fourth embodiment of the projection type liquid crystal image display device of the invention.

FIG. 5 is an overall plan view showing a fifth embodiment of the projection type liquid crystal image display device of the invention.

FIG. 6 is an overall plan view showing a sixth embodiment of the projection type liquid crystal image display device of the invention.

FIG. 7 is an overall plan view showing a seventh embodiment of the projection type liquid crystal image display device of the invention.

FIG. 8 is an overall plan view showing an eighth embodiment of an optical unit used in an image display device of the invention.

FIG. 9 is an overall plan view showing a ninth embodiment of the optical unit used in the image display device of the invention.

FIG. 10 is an overall plan view showing a tenth embodiment of the optical unit used in the image display device of the invention.

FIG. 11 is an overall plan view showing an eleventh embodiment of the optical unit used in the image display device of the invention.

FIG. 12 is an overall plan view showing a twelfth embodiment of the optical unit used in the image display device of the invention.

FIG. 13 is an overall plan view showing a thirteenth embodiment of the optical unit used in the image display device of the invention.

FIG. 14 is an overall plan view showing a fourteenth embodiment of the optical unit used in the image display device of the invention.

FIG. 15 is an overall plan view showing a fifteenth embodiment of the optical unit used in the image display device of the invention.

FIGS. 16A, 16B and 16C are drawings showing the permeance rate of the light.

FIGS. 17A and 17B are cross sectional plan views showing the embodiment for installing the liquid crystal element on the polarized beam splitter.

FIGS. 18A and 18B are perspective views showing an embodiment of the polarized beam splitter and an assembly base piece.

FIG. 19 is a side view for describing the installation of a 1/4 wavelength plate.

FIG. 20 is an overall perspective view showing an embodiment of the image display device of the invention.

FIG. 21 is a perspective view showing another embodiment of an optical system.

FIG. 22 is an overall perspective view showing another embodiment of the image display device of the invention.

FIG. 23 is a perspective view showing still another embodiment of the optical system.

FIG. 24 is an overall plan view showing a sixteenth embodiment of the projection type liquid crystal image display device of the invention.

FIG. 25 is an overall plan view showing a seventeenth embodiment of the projection type liquid crystal image display device of the invention.

FIG. 26 is an overall plan view showing an eighteenth embodiment of the projection type liquid crystal image display device of the invention.

FIG. 27 is an overall plan view showing a nineteenth embodiment of the projection type liquid crystal image display device of the invention.

FIG. 28 is an overall plan view showing a twentieth embodiment of the projection type liquid crystal image display device of the invention.

FIG. 29 is an overall plan view showing a twenty-first embodiment of the projection type liquid crystal image display device of the invention.

FIG. 30 is an overall plan view showing a twenty-second embodiment of the optical unit used in the image display device of the invention.

FIG. 31 is an overall plan view showing a twenty-third embodiment of the optical unit used in the image display device of the invention.

FIG. 32 is an overall plan view showing a twenty-fourth embodiment of the optical unit used in the image display device of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The embodiments of the invention are hereafter described while referring to the accompanying drawings.

An overall plan view showing the first embodiment of the projection is shown in FIG. 1. The embodiment in FIG. 1 shows three plate type projection display devices utilizing a total of three plates for the three primary colors R (red), G (green) and B (blue) constituted by reflective liquid crystal elements 2 as the liquid crystal light valves.

The projection display device in FIG. 1 contains a light source 1. The light source 1 is a white color lamp such as an ultra high voltage mercury lamp, metal halide lamp, xenon lamp, mercury xenon lamp or halogen lamp, etc. The light source 1 contains at least one reflective mirror 5 having a circular or polygonal output beam aperture and the light output from the light source 1 passes through the reflective liquid crystal elements 2 constituting the liquid crystal light valves, progresses to the projection lens 3 and is projected onto the screen 4.

The light emitted from the lamp of the light source 1 is condensed by a reflector 5 having an elliptical surface, or a radial surface or a non-spherical surface, and input to a first array lens 6 comprised by a plurality of condensing lenses installed in the output beam aperture of this reflective mirror 5 and rectangular frame of equivalent size, and the light beamed from the lamp unit is concentrated to form a plurality of secondary light source images on the first array lens 6. The light passes through a second array lens 7 comprised by a plurality of condensing lenses installed in the vicinity of the plurality of above mentioned secondary light source images and further forming images of the lens images of first array lens 6 on a liquid crystal display element 2. The emitted light beam is input to a row of diamond-shaped prisms of about half the size of each lens width installed for an appropriate pitch laterally along the optical axis of each lens of the second array lens 7. A polarized beam splitter 8 film has been coated on the surface of these prisms and the input light is separated into P polarized light and S polarized light by the polarized beam splitter 8. The P polarized light proceeds directly through the interior of the polarized beam splitter 8 and is rotated 90 degrees and deflected by the .lamda./2 wavelength polarizing plate 9 installed on the output beam surface of the prism, converted into S polarized light and output. The S polarized light on the other hand, is reflected by the polarized beam splitter 8, and after being reflected once more along the basic direction of the optical axis within the adjoining diamond-shaped prism, is output as S polarized light. The emitted light is input to a collimator lens 10.

In the projection type image display device using the reflective liquid crystal display elements of the related art, the polarized light is reflected in only one direction due to the combination of input light polarizing plate and reflective liquid crystal display elements, so that only about half the reflected light amount is obtained. However, by using the polarized beam splitter 8, a projection liquid crystal display device 2 having twice the brightness of the related art can theoretically be obtained by aligning along the direction of the random polarized light emitted from the light source 1 and inputting the light on the liquid crystal display element 2. Further, uniform quality can be obtained by overlapping the individual images of each lens cell of the array lens 6 on the liquid crystal display element 2.

The collimator lens 10 is comprised of at least one or more lenses, has a positive refractive potential, and has the effect of further concentrating the S polarized light. The light passing through this collimator lens 10 is deflected a specified 90 degrees by the optical axis direction of the reflective mirrors 11 and 12. The light then passes through a condenser lens 30 and beams onto (irradiates onto) the three RGB reflective liquid crystal display elements 2R, 2G, 2B so that light is separated into two portions, one of G (green) light and the other R, B (red and blue) light by the color separating prisms (not show in the drawing) or the color separating mirror 13, and input to the respective exclusive color polarized light separating/combining elements constituted by the polarized beam splitters 16G and 16RB. In other words, the G light is input to the G exclusive polarized beam splitter 16G of this invention, and is then an S polarized light, so is reflected to the reflective liquid crystal display element 2G and illuminates the panel. Further, the B light and R light passes the B-R exclusive polarizing plate 14, is input to the B-R exclusive beam splitter 16RB of this invention. Either the B light or the R light then passing through the designated wavelength converter element 17 that converts light only of that designated wavelength, is converted from S polarized light to P polarized light. The B light as P polarized light converted from polarized light for example, passes through the R-B exclusive beam splitter 16RB and illuminates the B exclusive reflective liquid crystal display element 2B. The R light on the other hand, is S polarized light so after being reflected by the R-B exclusive beam splitter 16RB is illuminated on the reflective liquid crystal display element 2B. The above description is of course only one example and the invention is not limited by this example. A configuration may be utilized wherein the R light is for example converted into P polarized light, or the original polarized light of the illuminating system may be P polarized light, and one of the RGB colors may be converted into S polarized light, and the remaining two colors constitute P polarized light. A R-B exclusive input polarizing plate 14 and a G exclusive polarizing plate 15 are installed on the light incident side of the reflective liquid crystal display elements 2R, 2G, 2B for each color, the polarization intensity of each color enhanced, a polarizing plate 14 stuck to the glass and the color purity enhanced by coating a color alignment film on the reflecting side. Then, the polarized light is exclusively converted by the reflective liquid crystal display elements 2 for each color, and the light then input again to the exclusive beam splitters 16G, 16RB, the S polarized light reflected and the P polarized light permeates through.

A plurality of reflective liquid crystal display elements 2 are formed to correspond to the number of display pixels (for example, 1024 horizontal pixels and 768 vertical pixels for each of the three colors, etc.). The light polarization angle of the pixels matching the liquid crystal display elements 2 changes according to an external drive signal, and ultimately a light is output in the polarization direction of the input beam and an intersecting direction, and light matching the polarized light direction is analyzed by the polarized beam splitter 2. The light intensity passing through the polarized beam splitter and the analyzed light intensity are determined for light along the deflection light angle, by its relation with the polarization angle of the polarized beam splitter 2. The image is in this way projected according to an externally input signal. At this time, the polarization direction is the same as the input light in the polarized light converter element constituted by the B exclusive beam splitter 16G and the R-B exclusive beam splitter 16RB of this invention, when a black display is shown on the reflective liquid crystal display elements 2R, 2G, 2B, and the light returns as is, along the light input path, to the light source side. However, the degree of deflection and extinction rate of the polarized beam splitter that constitute the light analyzing efficiency exert a minute effect on performance, and a slight leakage or disturbance in the polarized light passes through the polarized beam splitter, passes through the color combining mirror 19 or the color combining prism and illuminates onto the projection lens 20 and appears as a minute amount of brightness on the screen during a dark display. A decline in the contrast performance therefore occurs.

Of course the dielectric multilayer film forming the polarized light converter element and color separation/combining prism is applied to allow only a designated light wavelength from the input light through, in order to obtain a peak value of the permeance rate or reflection rate of that P polarized light or the permeance rate or reflection rate of that S polarized light, or permeance rate or reflection rate for a circular polarized light. The dielectric multilayer film allows only a limited light wavelength through, for example, a G exclusive beam splitter is coated with a dielectric multilayer film ideal for G light exclusively for a wavelength band in the vicinity from 500 nm to 600 nm, and utilizing an R-B exclusive polarized beam splitter 16 RB coated with a dielectric multilayer film ideal for R light and B light exclusively for the two wavelength bands in the vicinity from 400 nm to 500 nm and from the vicinity of 600 nm to 700 nm means that a dielectric multilayer film can easily be formed, and also that the permeance rate and reflective rate and further the (light) analyzing efficiency are improved compared to the related art. A reflective liquid crystal display device for high accuracy color restoration and high luminance, and high efficiency contrast can therefore be provided. By also adding an inclined (sloping) film or in other words a dielectric multilayer film whose film thickness changes according to the input angle of the light, an image of higher uniformity and high color purity can be obtained.

The light emitted from the exclusive polarized beam splitter 16 RB is converted to one-way R light or B light by the designated wavelength converter element 18, and both the R light and B light converted to S polarized light are input to the dichroic mirror 19.

The RGB light constituting the image is afterwards recombined by a color combining mirror such as the dichroic mirror 19 or a dichroic prism not shown in the drawing, and the light passed through a projection means 20 (for example a projection lens) such as a zoom lens and then arrives on the screen. The image formed by the reflective liquid crystal display elements 2R, 2G, 2B is shown as an enlarged projection image on the screen by the projection means 20. The reflective liquid crystal display device utilizing these three reflective liquid crystal display elements drives the lamp and the panel by means of a power supply 21.

The reflective liquid crystal display of the related art separates the light from the light source into the three colors R G B with at least one or more color separator prisms or color separator mirrors, analyzes each of the R G B light with at least three or more polarized beam splitters and after combining the three colors with the color combining prisms further projects the image on the screen using the projection lens so that the device was large overall, had a heavy weight and tended to have a high cost. This invention along with achieving a compact and light-weight device by means of a structure utilizing two units constituted by a G exclusive and a R-B exclusive polarized beam splitter, allows freely controlling the color purity, improves color irregularities and simultaneously improves performance. A projection type image display device, compact and with high brightness and high image quality can therefore be provided. Further, a cost reduction can be achieved because the number of component parts is reduced.

FIG. 2 is an overall plan view showing the second embodiment of the projection type liquid crystal image display device of the invention.

The R G B color light emitted from reflective liquid crystal display elements such as the reflective liquid crystal display elements 2R, 2G, 2B, or reflective intense inductive image display elements or drive micromirror image display elements, is analyzed by the polarized beams splitter 16G and polarized beam splitter 16RB that constitute the color separating/combination elements, and the color is then recombined by the dichroic prisms 19a and the light passes through a projection means 20 such as a zoom lens and arrives on the screen. The image formed on the reflective liquid crystal display elements 2R, 2G, 2B by the projection means 20 is projected as an enlarged image on the screen. The prism 19a of this invention has a size larger than the polarized beam splitter so that the light beam is not eclipsed, and the overall structure is compact so that the size is different to the beam splitter. The sloping (or inclining) film with the dichroic coating can be freely set so that an image with a high uniform color purity can be provided. Also in the structure of the invention, a support section is installed for an angle bevel 29 in the cabinet holding optical elements such as a dichroic prism 19a, by supporting the angle bevel 29 for the optical elements, the positioning and maintaining of the optical element such as the dichroic prism 19a is easily accomplished, assembly time is shortened during production, and the overall cost of the projection type display device can be reduced. The space savings achieved by this angle bevel 29 allow installing optical members for example a lens or other optical elements, to avoid the trouble from high density placement of components and achieve a compact device.

FIG. 3 is an overall plan view showing the third embodiment of the projection type liquid crystal image display device of the invention.

The light passes the condenser lens 30 and in order to illuminate the reflective liquid crystal display elements 2R, 2G, 2B for each R G B color, the light of a designated wavelength band is first converted to a polarization direction by means of a designated wavelength converter element 28. In this case, if the illuminating light is S polarized light then it is converted to P polarized light, and separated into each color by the wideband polarized beam splitter 16 RGB. If for instance G polarized light is converted by the designated wavelength converter element 28, the light is divided into two portions, one G light and the other R, B light by the polarized beam splitter 16 RGB and then input to the respective exclusive polarized color separator/synthesizer element consisting of polarized beam splitters 16G, 16RB. In other words, the P polarized light of the G light is converted into S polarized light by the designated wavelength converter element 27, input to the G exclusive polarized beam splitter 16G, and then reflected back to the G exclusive reflective liquid crystal display element 2G since the light is S polarized light, and beamed onto the liquid display element 2G. Also, the B light and R light passes the B-R exclusive polarizing plate 14, is beamed onto the R-B exclusive beam splitter 16 RB, and then transits the R-B exclusive beam splitter 16 RB to convert only light on the designated wavelength band to the polarization direction, and the polarized light of either the B light or the R light is converted from S polarized light to P polarized light and the B light for example converted to P polarized light, transits the R-B exclusive beam splitter 16 RB and illuminates the B exclusive reflective liquid crystal display element 2B. The R light on the other hand is an S polarized light so after being reflected by the R-B exclusive beam splitter 16 RB is illuminated onto the R exclusive reflective liquid crystal display element 2R.

The above description is of course only one specific example and this invention is not limited to this example. A structure may also be utilized wherein the R light may be converted into P polarized light, the polarized light of a different lighting system may originally be P polarized light, and one color from R G B is converted to S polarized light and the remaining two colors be P polarized light. An RB exclusive input light polarizing plate 14 and a G exclusive input light polarizing plate 15 may be installed on the incident side for the S polarized light to permeate each of the exclusive color reflective liquid crystal elements 2R, 2G, 2B, and the degree of deflection of each color and color purity enhanced. Afterwards, the polarized light is converted by the reflective image display element 2 for each exclusive color, the light input again to the polarized beam splitters 16G, 15RB for each exclusive color, the S polarized light reflected and the P polarized light permeates through.

A plurality of reflective liquid crystal display elements 2 are formed to correspond to the number of display pixels (for example, 1024 horizontal pixels and 768 vertical pixels for each of the three colors, etc.). The light polarization angle of the pixels matching the liquid crystal display elements 2 changes according to an external drive signal, and ultimately a light is output in the polarization direction of the input beam and an intersecting direction, and light matching the polarized light direction is analyzed by the polarized beam splitter 16. The light intensity passing through the polarized beam splitter and the analyzed light intensity are determined for light along the deflection light angle, by its relation with the polarization angle of the polarized beam splitter 16. The image is in this way projected according to an externally input signal. At this time, the polarization direction is the same as the input light in the polarized light converter elements constituted by the B exclusive beam splitter 16G and the R-B exclusive beam splitter 16RB of this invention, when a black display is shown on the reflective liquid crystal display elements 2R, 2G, 2B, and the light returns as is, along the light input path, to the light source side.

The RGB light constituting the image is afterwards recombined by a color combining mirror such as the dichroic mirror 19 or a dichroic prism not shown in the drawing, and the light passed through a projection means 20 (for example a projection lens) such as a zoom lens and then arrives on the screen. The image formed by the reflective liquid crystal display elements 2R, 2G, 2B is shown as an enlarged projection image on the screen by the projection means 20. The reflective liquid crystal display device utilizing these three reflective liquid crystal display elements drives the lamp and the panel by means of a power supply 21.

The reflective liquid crystal display of the related art separates the light from the light source into the three colors R G B with at least one or more color separator prisms or color separator mirrors, analyzes each of the R G B light with at least three or more polarized beam splitters and after combining the three colors with the color combining prisms further projects the image on the screen using the projection lens so that the device was large overall, had a heavy weight and tended to have a high cost. This invention along with achieving a compact and light-weight device by means of a structure utilizing two units constituted by a G exclusive and a R-B exclusive polarized beam splitter, allows freely controlling the color purity, improves color irregularities and simultaneously improves performance. The color separation mean combines the polarized beam splitter with designated wavelength converter elements so that there are few of the effects accompanying angular dependence and consequently calculating the color performance is easy. A projection type image display device, that is compact and has high brightness and high image quality can therefore be achieved. Further, a cost reduction can be achieved because the number of component parts is reduced.

FIG. 4 is an overall plan view showing the fourth embodiment of the projection type liquid crystal image display device of the invention.

In addition to the effect of the embodiment of FIG. 3, the R G B color light emitted from the reflective liquid crystal display elements 2R, 2G, 2B is analyzed by the polarized beams splitter 16G and polarized beam splitter 16RB that constitute the color separating/combination elements, and the light for R G B color is then recombined by the dichroic prisms 19a and the light passes through a projection means 20 and arrives on the screen. The image formed on the reflective liquid crystal display elements 2R, 2G, 2B by the projection means 20 is projected as an enlarged image on the screen. The prism 19a of this invention has a size larger than the polarized beam splitter so that the light beam is not eclipsed, and the overall structure is compact so that the size is different to the polarized beam splitter. The sloping (or inclining) film of the dichroic coating can be freely set so that an image with a high uniform color purity can be provided.

Also in the structure of the invention, a support section is installed with a support section for angle bevel 29 in a cabinet holding optical elements such as a dichroic prism 19a. By supporting the angle bevel 29 for the optical elements, the positioning and maintaining of an optical element such as the dichroic prism 19a are easily accomplished, assembly time is shortened during production, and the overall cost of the projection type display device can also be reduced. The space savings achieved by this angle bevel 29 allow installing optical members for example polarized light separating elements constituted by a polarized beam splitter 16 RGB, to avoid the trouble resulting from high density placement of components and achieve a compact device. FIG. 5 is an overall plan view showing the fifth embodiment of the projection type liquid crystal image display device of the invention, and shows in particular the structure of the optical system.

In FIG. 5, a light source unit comprised of a reflector 2 and a light source 1 is installed in the image display device. The light emitted from the light source unit passes through a polarity rectifier element 31 such as a polarizing plate or polarizing beam splitter (PBS), and light rectified as P polarized light is separated into G light (green light) and, R light (red light) and B light (blue light) by the green color separator mirror 13. The separated G light is input to the polarized beam splitter 16B, the input light permeates through as P polarized light, is input to the image display element constituted by reflective liquid crystal display element 2G, the polarized converted light is received and reflected according to the video signal, and input again to the polarized beam splitter 16G. The polarized beam splitter 16G analyzes the input light according to the polarization conversion level received per the reflective liquid crystal display element 2G, or in other words reflects only the S polarization components of the polarized converted light from among the light that was input, and obtains the image.

The R light and the B light separated by the green color separation mirror 13 are input to the polarized beam splitter 16RB only as R light S polarized light. The R light which is S polarized light is reflected by the polarized beam splitter 16RB and input to the reflective liquid crystal display element 2R.

The light input to the reflective liquid crystal display element 2R is received and reflected as polarized light, according to the image signal and input again to the polarized beam splitter 16RB. In the polarized beam splitter 16RB, the light is analyzed according to the polarized light conversion level received by the reflective liquid crystal display element 2R, and an image obtained. The B light permeates the polarized beam splitter 16RB as P polarized light, and is input to the reflective liquid crystal display element 2B. The light input to the reflective liquid crystal display element 2B receives polarity conversion according to the video signal, is reflected and is input again to the polarized beam splitter 16RB. In the polarized beam splitter 16RB, the light is analyzed according to the polarized light conversion level received by the reflective liquid crystal display element 2B, and an image obtained.

Though not shown in the drawing, the S polarized light of just the B light may be polarized-converted by the designated wavelength converter element 17 the converts a designated light wavelength into a polarized direction. The S polarized light of the polarity converted B light is at this time input to the polarized beam splitter 16RB. The B light consisting of S polarized light is reflected by the polarized beam splitter 16RB, and input to the reflective liquid crystal display element 2B. The light input to the reflective liquid crystal display element 2B receives polarity conversion according to the video signal is reflected and is input again to the polarized beam splitter 16RB. In the polarized beam splitter 16RB, the light is analyzed according to the polarized light conversion level received by the reflective liquid crystal display element 2B, and an image obtained. The R light permeates the polarized beam splitter as P polarized light, and is input to the effective liquid crystal display element 2R. The light input to the reflective liquid crystal display element 2R receives polarity conversion according to the video signal is reflected and is input again to the polarized beam splitter 16RB.

In the polarized beam splitter 16RB, the light is analyzed according to the polarized light conversion level received by the reflective liquid crystal display element 2R, and an image obtained.

The respective images of the red, blue and green light that were obtained are combined (synthesized) by a color combining means 19 such as for example a dichroic mirror or a dichroic prism, and projected by means of the projection lens 20. A designated wavelength converter element 18 to convert the polarity direction of a designated wavelength may be inserted on the output side of the polarized beam splitter 16RB at this time, to align the polarity directions of the R light and B light. A polarization screen can also be used at this time setting designated wavelength converter elements 18 to convert the polarity direction of designated wavelengths for all the R light, G light and B light, for aligning their polarity directions.

Alternatively, a polarization converter element 32 can be installed on the optical path of the G light to convert light analyzed by the polarized beam splitter 16G from S polarized light to P polarized light, and input the P polarized light to the color combining means such as a color combining mirror 19. Further, designated wavelength bands can be set with a designated wavelength converter element 18 to polarity-convert light on a designated wavelength so that either or both the R light or B light polarity directions are S polarized light. The permeance band of the G light is in this way widened and either or both of the R light, B light reflection bands are capable of being widened by means of the polarity characteristics of the dichroic mirror or the dichroic coating constituting the color combining means 19.

The polarity rectifier elements 33, 34, 35 such as polarizing plates may be installed on the incident side or the output side of the polarized beam splitter 16G or the polarized beam splitter 16RB. At this time, the polarity rectifier element 33 installed on the incident side of the polarized beam splitter 16RB on the R or B optical path, is installed on the incident side of the optical element 17 for converting the polarization direction of the designated wavelength band. Also, the polarity rectifier element 35 installed on the incident side of the polarized beam splitter 16RB, is installed onto he output side of the designated wavelength converter element 18 for converting the polarization direction of the designated wavelength band.

The structure of this invention utilizing two polarized beam splitters, along with being compact and lightweight, can freely regulate the color purity and improves color irregularities.

FIG. 6 is an overall plan view showing the sixth embodiment of the projection type liquid crystal image display device of the invention, and indicates the structure of the optical system.

In FIG. 6, a light source unit comprised of a reflector 2 and a light source 1 is installed in the image display device, the light source 1 is a white color lamp. The light emitted from the light source unit passes through a polarity rectifier element 8 such as a polarizing plate or a polarization conversion element (polarizing beam splitter), and the light rectified as S polarized light is separated into G light (green light) and, R light (red light) and B light (blue light) by the green color separator mirror 13.

The separated G light is input to the polarized beam splitter 16G, the input light permeating through as S polarized light, is input to the image display element constituted by reflective liquid crystal display element 2G, the polarized converted light is received and reflected according to the video signal, and input again to the polarized beam splitter 16G.

The polarized beam splitter 16G analyzes the input light according to the polarization conversion level received per the reflective liquid crystal display element 2G, or in other words reflects only the P polarization components of the polarized converted light from among the light that was input, and obtains the image.

The R light and the B light separated by the green color separation mirror 13 are input to the polarized beam splitter 16RB only as R light S polarized light by the optical element 17 for converting the polarization direction of the designated wavelength band. The R light which is P polarized light permeates per the polarized beam splitter 16RB and is input to the reflective liquid crystal display element 2R.

The light input to the reflective liquid crystal display element 2R is received and reflected as polarized light, according to the image signal and input again to the polarized beam splitter 16RB. In the polarized beam splitter 16RB, the light is analyzed according to the polarized light conversion level received by the reflective liquid crystal display element 2R, and an image obtained. The B light permeates the polarized beam splitter 16RB as S polarized light, and is input to the reflective liquid crystal display element 2B. The light input to the reflective liquid crystal display element 2B receives polarity conversion according to the video signal, is reflected and is input again to the polarized beam splitter 16RB. In the polarized beam splitter 16RB, the light is analyzed according to the polarized light conversion level received by the reflective liquid crystal display element 2B, and an image obtained.

Though not shown in the drawing, the P polarized light of just the B light may be polarized-converted by the designated wavelength converter element 17 that converts a designated light wavelength into a polarized direction. The P polarized light of the polarity converted B light is at this time input to the polarized beam splitter 16RB. The B light consisting of P polarized light permeates through the polarized beam splitter 16RB, and is input to the reflective liquid crystal display element 2B. The light input to the reflective liquid crystal display element 2B receives polarity conversion according to the video signal is reflected and is input again to the polarized beam splitter 16RB. In the polarized beam splitter 16RB, the light is analyzed according to the polarized light conversion level received by the reflective liquid crystal display element 2B, and an image obtained. The R light permeates the polarized beam splitter as S polarized light, and is input to the reflective liquid crystal display element 2R. The light input to the reflective liquid crystal display element 2R receives polarity conversion according to the video signal is reflected and is input again to the polarized beam splitter 16RB.

In the polarized beam splitter 16RB, the light is analyzed according to the polarized light conversion level received by the reflective liquid crystal display element 2R, and an image obtained.

The respective images of the red, blue and green light that were obtained are combined (synthesized) by a color combining means 19 such as for example a dichroic mirror or a dichroic prism, and projected by means of the projection lens 20. A designated wavelength converter element 18 to convert the polarity direction of a designated wavelength may be inserted on the output side of the polarized beam splitter 16RB at this time, to align the polarity directions of the R light and B light. A polarization screen can also be used at this time setting designated wavelength converter elements 18 to convert the polarity direction of designated wavelengths for all the R light, G light and B light, for aligning their polarity directions.

Alternatively, at this time, designated wavelength bands can be set with a designated wavelength converter element 18 to polarity-convert light on a designated wavelength so that either or both the R light or B light polarity directions on the R light and B light optical paths are S polarized light. The permeance band of the G light is in this way widened and either or both of the R light, B light reflection bands are capable of being widened by means of the polarization characteristics of the dichroic mirror or the dichroic coating constituting the color combining means 19.

The polarity rectifier elements 33, 34, 35 such as polarizing plates may be installed on the incident side or the output side of the polarized beam splitter 16G or the polarized beam splitter 16RB. At this time, the polarity rectifier element 33 installed on the incident side of the polarized beam splitter 16RB on the R or B optical path, is installed on the incident side of the optical element 17 for converting the polarization direction of the designated wavelength band. Also, the polarity rectifier element 35 installed on the incident side of the polarized beam splitter 16RB on the optical path of the R light and B light, is installed on the light output side of the designated wavelength converter element 18 for converting the polarization direction of the designated wavelength band.

The structure of this invention utilizing two polarized beam splitters, along with being compact and lightweight, can freely regulate the color purity and improves color irregularities.

FIG. 7 is an overall plan view showing the seventh embodiment of the projection type liquid crystal image display device of the invention.

The embodiment of FIG. 7 shows a three plate type projection display device using a total of three plates corresponding to the three primary colors, R (red), G (green) and B (blue) constituted by the reflective liquid crystal display elements 2R, 2G, 2B as the liquid crystal light valves.

The light source 1 in the projection type liquid crystal display device of FIG. 7 is a white color lamp.

The light emitted from the light source 1 is reflected from at least one reflective surface mirror 5 having an output aperture of a circular or a polygonal shape. The light passes through the reflective liquid crystal display elements 2R, 2G, 2B constituting the liquid crystal light valves, progresses towards the projection lens 20 and is projected on the screen.

A dichroic prism or a dichroic mirror 13 as the color separating means between the polarized beam splitter 8 and the reflective liquid crystal display elements 2, permeates or reflects only the G light from among the three light colors of R light, B light, G light, and the G light is separated from the other B light and G light. The G light separated by the dichroic mirror 13 is permeated or reflected by the polarized beam splitter 16G. The polarizing plates 15, 29 having a polarizing rectifying effect on the G light may be installed on the incident side or the output side of the polarized beam splitter 16G at this time. The light input onto the liquid crystal display element 2G is respectively modulated and readout light, reflected and se