JPH11202430A - Projection type image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the device small-sized and lightweight and to obtain light display. SOLUTION: In front of a light source 101, a dichroic mirror 103 is arranged which transmits light of the wavelength band of red of the white light from the light source 101 and reflects light in the wavelength band of green and blue. The light of red transmitted through the dichroic mirror 103 is made incident on a polarized light separating element 104 and only S-polarized light is made incident on a reflection type liquid crystal display element 105R. The light of the wavelength band of green and blue reflected by the dichroic mirror 103 is made incident on a narrow-band polarized light separating element which transmits light of the wavelength of blue, reflects S-polarized light of green, and transmits P-polarized light of green and the S-polarized light of green is reflected toward a reflection type liquid crystal display element 105G. The light of blue having been transmitted through the narrow-band polarized light separating element 106 is reflected by a reflecting mirror 107 and then made incident on a polarized light separating element 108, which reflects only its S-polarized light component toward a reflection type liquid crystal display element 105B.

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 device such as a liquid crystal projector, and more particularly, to modulating light from a light source with an image display device such as a liquid crystal display device. The present invention relates to a projection type image display device that enlarges and projects light on a screen by a projection lens.

[0002]

2. Description of the Related Art The above-mentioned liquid crystal display device changes the optical characteristics of a liquid crystal by applying a driving voltage corresponding to an image signal to pixel electrodes which are regularly arranged in a matrix. Is configured to be displayed. There are the following two methods for applying an independent drive voltage to the pixel electrode. One method is a simple matrix method, and the other method is a non-linear matrix.
This is an active matrix method in which terminal elements and three-terminal elements are provided in a liquid crystal display element.

[0003] In the case of the latter active matrix system, an MIM (metal-metal) for driving a pixel electrode on and off is used.
It is necessary to provide a switching element such as an insulator-metal) element or a TFT (thin film transistor) element, and a wiring electrode for supplying a driving voltage to the pixel electrode.

In the switching element, when strong light is incident on the switching element, the resistance of the element in the OFF state decreases, and the charge charged when a voltage is applied is discharged. There is a drawback that a normal driving voltage is not applied to the liquid crystal portion, and light leaks even in a black state, thereby lowering the contrast ratio.

Therefore, when the liquid crystal display element is of a transmission type, as shown in FIG. 15, a TFT 1601 as a switching element is provided on a TFT substrate provided with pixel electrodes.
In addition, it is necessary to provide a black matrix 1602 as a light shielding means on a counter substrate opposed to the TFT substrate with a liquid crystal layer (not shown) interposed therebetween to block light incident on the TFT 1601. Therefore, in the case of a transmissive liquid crystal display element, in addition to the TFT 1601 having light shielding properties, the gate bus line 1603 and the source bus line 1604 as wiring electrodes, the black matrix 16
Since the light is also shielded by 02, the area of the effective pixel opening occupying the pixel section, that is, the aperture ratio is reduced.

Furthermore, it is difficult to form these switching elements and wiring electrodes in a size smaller than a certain size due to restrictions on their electrical performance and manufacturing technology. Therefore,
The aperture ratio is further reduced as the pitch of the pixel electrodes becomes smaller as the definition and size of the liquid crystal display element become higher and smaller.

In order to solve this problem, a reflection type liquid crystal display device has been developed. As shown in FIG. 16, the reflection type liquid crystal display element has a T
Since the reflective pixel electrode 1700 can be formed over the FT 1601, the same liquid crystal display element size
The aperture ratio can be made larger than that of the transmissive liquid crystal display element, which is very effective in improving the brightness of the projection type liquid crystal display device.

Various systems have been proposed in which such a reflection type liquid crystal display device is applied to a projection type image display device. As proposals, JP-A-4-338721 and EIAJ
/ SEMI Sponsored Electronic Display Forum 97, Lectures on pages 3-27 to 3-32 (1997, 4,
16-18) and JP-A-4-319910.

The projection type image display device proposed in Japanese Patent Application Laid-Open No. 4-338721 is constructed as shown in FIG. That is, the light emitted from the light source 11 is separated by the polarizing beam splitter (PBS) 12 into linear polarization components in two directions orthogonal to each other. 11a in the figure is a parabolic mirror.
Of the separated light, the light reflected by the PBS 12 enters the color separation / combination cross dichroic prism 13.
In the cross dichroic prism 13 for color separation / synthesis,
The incident white light is separated into light of three primary colors of R (red), G (green), and B (blue), and is incident on the reflective liquid crystal display element 14 corresponding to each color. The light reflected by each reflective liquid crystal display element 14 is composed by a cross dichroic prism 13 for color separation / combination, passes through the PBS 12, and is projected on a screen 16 by a projection lens 15.

The basic principle of the projection type image display device of the type proposed in the electronic display forum 97 is the same as that of the projection type image display device of the above-mentioned JP-A-4-338721 as shown in FIG. Separation is performed by two dichroic mirrors 17 arranged on the light source 11 side of the polarization beam splitter 12, and a cross dichroic prism 13 for performing color synthesis is arranged on the projection lens 15 side of the polarization beam splitter 12. Reference numeral 18 denotes a reflection mirror.

Although a projection type image display device proposed in Japanese Patent Application Laid-Open No. 4-319910 is not shown, a system using a light scattering type liquid crystal display device as a reflection type liquid crystal display device and having a schlieren optical system is disclosed. I have.

[0012]

However, the projection type image display device using the above-mentioned reflection type liquid crystal display element has the following problems.

In the configuration of Japanese Patent Application Laid-Open No. 4-338721, FIG.
As shown in FIG. 7, the birefringent mode reflection type liquid crystal display element 14
Is used, the polarization state of the light incident on the cross dichroic prism 13 is different by 90 ° between the forward path and the return path. Since the cross dichroic prism 13 generally has large polarization dependence on its reflection surface, the spectral characteristics are large when the white light is separated into R, G, and B lights on the outward path and when the white light is combined on the return path. shift.

FIG. 19A shows an example of spectral characteristics of the reflected light of B color with respect to S-polarized light and P-polarized light by the cross dichroic prism, and FIG. 19B shows the reflection of R color by the cross dichroic prism. 4 shows an example of spectral characteristics of light with respect to S-polarized light and P-polarized light.

As can be understood from this figure, both S-polarized light and P-polarized light are incident on the cross dichroic prism, but R and B largely depend on the brightness of the projection and the color reproduction range. Is P-polarized light having a narrower band than S-polarized light for each color light, and P-polarized light for G color light.
S-polarized light having a narrower band than polarized light.

However, as shown in FIG.
When the brightness and color reproduction range of the R and B color lights, which are limited by the polarization, are adjusted, the wavelength dependence on the P polarization and the S polarization is large. As shown in the figure, the display becomes narrow, and the display of G color light and the white balance are hindered. Conversely, if the brightness or color reproduction range of the G color light is adjusted, the same problem as that of the G color light occurs for each of the R and B color lights as shown in FIG.

Further, when there is a wavelength shift of the spectral characteristics with respect to the P-polarized light and the S-polarized light, the following problem occurs. As shown in FIG. 21, for example, when S-polarized light enters the cross dichroic prism 13, the reflection type liquid crystal display element 14 </ b> R corresponding to the R color light has S-polarized light in the R band reflected by the cross dichroic prism 13. (A) is incident. Then, the reflection type liquid crystal display element 14R
, The polarization state is modulated according to the image signal and reflected. As shown in FIG. 22, the reflected light contains a P-polarized component due to this modulation. The light (b) in the shaded area shown in FIG. 22 passes through the R reflecting surface of the cross dichroic prism 13 and enters the liquid crystal display element 14B corresponding to the B color light. When this light is changed to S-polarized light again by the liquid crystal display element 14B, the reflected light S
The polarized light (c) does not return to the liquid crystal display element 14R corresponding to the R color light, but is reflected in the direction of the liquid crystal display element 14G corresponding to the G color light. Liquid crystal display element 14 corresponding to G color light
When this light is changed to P-polarized light again by G, the P-polarized light (d) reflected by the liquid crystal display element 14G corresponding to the G color light
Is transmitted through the R reflecting surface of the cross dichroic prism 13 and enters the projection lens, and is projected on the screen as stray light or ghost.

The above-mentioned problem of stray light and ghost similarly appears for light of the B color band, and even when P-polarized light is incident on the cross dichroic prism 13, the problem of stray light and ghost occurs on the same principle. I do.

On the other hand, in the method proposed in the electronic display forum 97, as shown in FIG. 18, color separation is performed by two dichroic mirrors 17 provided on the light source 11 side of the polarizing beam splitter 12, and color synthesis is performed by polarization. Since the cross dichroic prism 13 provided on the projection lens 15 side of the beam splitter 12 performs the above, the above-described problem does not occur. However, a block portion for performing color separation surrounded by a dotted line in FIG. 18 is required, and a projection type image display using a transmission type liquid crystal display element 24 instead of the reflection type liquid crystal display element 14 as shown in FIG. There is a disadvantage that the system size is larger than the optical system for the device.

In the configuration of JP-A-4-319910, since a light scattering type liquid crystal display element is used, non-polarized light (randomly polarized light) basically enters the cross dichroic prism. There is no shift in the spectral spectrum between the forward path and the return path, which occurs in the configuration. However, since the average spectrum of the P-polarized light and the S-polarized light with respect to the color separation surface of the cross dichroic prism is obtained, as shown in FIG. 50% rate
It shows a step-like characteristic in the vicinity. Therefore, R, G, B
The color purity and the light use efficiency of the liquid crystal are extremely reduced. In addition,
FIG. 24A shows an example of spectral characteristics of the B-color reflected light with respect to P-polarized light and S-polarized light, and FIG. 24B shows an example of the spectral characteristics of the R-color reflected light with respect to P-polarized light and S-polarized light.

SUMMARY OF THE INVENTION The present invention has been made to solve such problems of the prior art, and is a projection type image display using a reflection type liquid crystal display element which is small, lightweight and capable of bright display. It is intended to provide a device.

[0022]

According to a first aspect of the present invention, there is provided a projection type image display apparatus, wherein a light source and light from the light source are color-separated into a plurality of lights having different wavelength bands. An optical unit composed of a plurality of optical elements that transmits or reflects according to the polarization direction to separate the polarization, and a reflection type image display element that receives light from the optical unit and modulates the polarization direction in accordance with an image signal; In a projection type image display apparatus comprising: a color synthesizing element for synthesizing light modulated by an image display element; and projection means for projecting the light synthesized by the color synthesizing element, at least one optical element of the optical means Comprises an optical element having both functions of color separation and polarization separation, thereby achieving the above object.

According to a second aspect of the present invention, in the projection type image display device, the optical element having both functions of the color separation and the polarization separation includes at least one wavelength band of three primary colors of red, green and blue. , A dielectric mirror that reflects an S-polarized component and transmits a P-polarized component with respect to a surface having functions of color separation and polarization separation.

According to a third aspect of the present invention, there is provided the projection type image display device, wherein the optical element having both the functions of color separation and polarization separation has an optical element in a plane having the functions of color separation and polarization separation. A linearly polarized light having an anisotropic axis, reflecting a linearly polarized light component of incident light parallel to the optically anisotropic axis in at least one wavelength band of the three primary colors of red, green and blue, and orthogonal to the reflected light; It is an optical element having a function of transmitting components.

According to a fourth aspect of the present invention, in the projection type image display device, the optical element having both functions of the color separation and the polarization separation corresponds to a reflection type image display element for green, and is provided with blue or red light. An optical element that transmits light in at least one of the wavelength bands and has a polarization separation function in a green wavelength band.

According to a fifth aspect of the present invention, in the projection type image display device, at least one of the optical elements having both functions of the color separation and the polarization separation has one wavelength among the three primary colors of red, green and blue. It is a stacked element in which two elements having a polarization separation function in a band and transmitting light in another wavelength band are stacked with their optical anisotropy axes orthogonal to each other.

According to a sixth aspect of the present invention, in the projection type image display device, at least one of the optical elements having both the functions of color separation and polarization separation has one of three primary colors of red, green and blue. Two elements that have a polarization splitting function in the band and transmit light in other wavelength bands were set with the optical anisotropy axes of each element parallel, and a half-wave plate was placed between both elements. It is a three-layer laminated element.

According to a seventh aspect of the present invention, there is provided the projection type image display device, wherein the reflection type image display element corresponds to each of the transmitted light and the reflected light from the laminated element.
The light having the same polarization direction is separated by being transmitted and reflected by the wavelength band by the laminated element, and each light is made incident on the corresponding reflection type liquid crystal display element, and the polarization direction is modulated by the reflection type image display element. The light is synthesized.

In the projection type image display device according to the eighth aspect of the present invention, the laminated element may include a red light source, a green light source and a blue light source included in the light source.
It is an optical element having a function of separating primary color light into light of two colors whose polarization directions traveling in the same direction are orthogonal to each other and the remaining light.

According to a ninth aspect of the present invention, there is provided the projection type image display device, wherein light of three primary colors of red, green and blue other than light of two colors separated in the same direction and polarized in the same direction and separated by the laminating element is orthogonal. Out of the remaining light other than the two colors separated by the stacked element, and the P-polarized light or S-polarized light of the remaining one color
It is characterized by having a polarization separation element having a function of selecting one of the polarized lights and making it incident on the corresponding reflection type image display element.

According to a tenth aspect of the present invention, there is provided the projection type image display device, wherein at least one of the three primary colors of red, green and blue has
It is characterized by including a polarizing filter for cutting either the polarized light component or the S polarized light component.

A projection type image display apparatus according to an eleventh aspect of the present invention is characterized in that at least one of the three primary colors of red, green and blue is provided with a wave plate for changing the polarization direction of light.

The operation of the present invention will be described below.

According to the first aspect of the present invention, in the projection type image display device using the reflection type image display device, an optical element having both functions of color separation and polarization separation is used, so that a separate image display device is used. Since color separation and polarization separation performed by the element can be performed simultaneously by one optical element, brightness,
C. The number of components can be reduced without deteriorating the display characteristics such as R., and the size and cost of the optical system can be significantly reduced. In addition, by performing color separation and color synthesis using separate optical elements, there is no influence of the polarization dependence of the elements, which is a problem in JP-A-4-338721, and red, green, and
There is no problem such as deviation of blue color purity, white balance, and ghost.

According to the second aspect of the present invention, by using a dielectric mirror as an optical element having both functions of color separation and polarization separation, the polarization dependence of the spectral characteristics of the dielectric mirror with respect to obliquely incident light is obtained. Can be used, color separation and polarization separation can be performed efficiently, and a bright projection image display device can be realized.

According to the configuration of the third aspect, an element having optical anisotropy in the color separation (or polarization separation) plane is used as the optical element having both functions of color separation and polarization separation. By doing so, the polarization direction of the light incident on the reflective image display device can be arbitrarily selected by rotating the optically anisotropic axis. Therefore, light having an optimal polarization direction can be easily incident according to the characteristics of the optical system and the reflection type image display device, and a bright and good CR image display device can be realized.

According to the structure of the fourth aspect, an optical element having both functions of color separation and polarization separation is made to correspond to a reflection type image display element for green, as shown in FIG. In the configuration, with respect to the cross dichroic prism, which is a color synthesizing means, it is possible to transmit green and reflect blue and red to perform color synthesis. As a result, on the green reflection surface, the number of dielectric films increases and the cost increases as compared with the blue and red reflection dielectric films, but by adopting the green transmission structure, the cross dichroic prism can be manufactured at low cost. Can be made. Furthermore, according to the present configuration, by combining red and blue lights that do not have continuous wavelength bands by reflecting them, it is possible to suppress the occurrence of light loss and stray light during color synthesis.

According to the fifth aspect of the present invention, an optical element having both functions of color separation and polarization separation is formed by laminating two optical elements with orthogonal optical anisotropy.
Since the same function as the two elements having the functions of the color separation and the polarization separation can be performed by the two stacked elements, the optical system can be further reduced in size.

According to the sixth aspect of the present invention, an optical element having both functions of color separation and polarization separation is provided by setting an optical anisotropy axis to be parallel and a half-wave plate between the two elements. By using a three-layered laminated element having the above-mentioned structure, a single laminated element can perform the same function as the two elements having the functions of the color separation and the polarization separation described above. Can be

According to the configuration of claim 7, it is possible to eliminate the conventional configuration in which the polarization splitting element and the reflection type image display element have a one-to-one correspondence. In other words, by adopting this configuration, one reflective image display element corresponds to each of the transmitted light and the reflected light from one laminated element, so that not only can the optical system be miniaturized, but also Since the polarization direction of the light incident on the multilayer element is aligned in the same direction, in the direction of the multilayer element,
As an element for directing light, an inexpensive dichroic mirror that simply performs color separation can be used, so that cost can be reduced.

According to the eighth aspect of the present invention, the laminated element separates two colors of light having orthogonal polarization directions from the three primary colors of red, green and blue contained in the light source in the same direction. In contrast to the conventional configuration in which a polarization splitting element and a reflection type image display element have a one-to-one correspondence, one polarization splitting element is used.
Since the light from the laminated element can be distributed to two reflective image display elements, the size of the optical system can be reduced.

According to the ninth aspect of the present invention, three colors of red, green, and blue are provided.
The remaining light of the primary colors other than the two colors of light separated by the layered device and having the polarization directions orthogonal to each other is incident on a polarization separation element that causes the remaining one color to be incident on the corresponding reflective image display element. At this time, by providing this polarization splitting element with a function of selecting only P-polarized light or S-polarized light of the remaining one color of light, light that does not contribute to display can be cut, and an image having a high contrast ratio and no ghost can be obtained. Can be realized.

According to the tenth aspect, by providing a polarizing filter for cutting at least one of the P-polarized component and the S-polarized component to at least one optical path of the three primary colors, In addition to preventing the reduction of the contrast ratio of the projected image due to light leakage,
Ghosts generated by the following principle can be cut.

FIG. 25 shows an example of a ghost generation mechanism. When the light incident on the multilayer element 1105 is linearly polarized light, each component light is reflected on the corresponding reflection type image display element 1.
4G and 14B, when the light incident on the multilayer element 1105 is naturally polarized light, the light having one polarization component is
The light is incident not on the corresponding reflective image display element but on a different reflective image display element. For example, the reflection type image display device 1
When the multilayer element 1105 is set so that green S-polarized light enters 4G, the green P
The polarized light enters the reflective image display element 14B, is modulated, and then enters the screen as S-polarized light, which becomes a ghost.

According to the eleventh aspect of the present invention, a cross dichroic prism, a color separation element, and a wavelength plate for rotating the polarization direction of light are provided on the red, green, and blue optical paths.
Since the polarization direction of the incident light can be changed according to the spectral characteristics of the polarization separation element and the characteristics of the reflection type image display element, the light utilization factor and the color purity of red, green, and blue can be improved.

[0046]

Embodiments of the present invention will be specifically described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a schematic diagram showing a projection type color image display device of Embodiment 1.

In the present embodiment, 150 is used as the light source 101.
W, a metal halide lamp having an arc length of 3 mm was used.
As a light source, a halogen lamp or a xenon lamp can be used. On the back of the light source 101, a parabolic mirror 102 for emitting light from the light source as substantially parallel light
Is arranged.

In front of the light source 101, a dichroic mirror 103 that transmits light in the red wavelength band of white light from the light source 101 and reflects light in the green and blue wavelength bands is arranged. The red light transmitted through the dichroic mirror 103 is incident on the polarization splitter 104, and only the S-polarized light is incident on the reflective liquid crystal display element 105R. On the other hand, light in the green and blue wavelength bands reflected by the dichroic mirror 103 transmits light in the blue wavelength band, reflects green S-polarized light, and transmits green P-polarized light. ,
An element having a polarization splitting function only in a specific wavelength band in visible light, such as the above-described element, is referred to as a narrow-band polarization splitting element) 106, and the green S-polarized light is reflected by a reflective liquid crystal display element. The light is reflected in the direction of 105G.

The blue light transmitted through the narrow-band polarized light separating element 106 is reflected by a reflecting mirror 107 and then enters a polarized light separating element 108. The polarized light separating element 108 reflects only the S-polarized light component of the reflective liquid crystal display element 105B. In the direction of.

In this embodiment, the polarization separation element 10
A polarization selective reflection film (Optical Film D-BEF) manufactured by 3M was used for 4 and 108, but a polarization beam splitter (PB) made of a dielectric film was used.
S) or a polarizing element disclosed in JP-A-57-158801. The polarizing element disclosed in D-BEF and Japanese Patent Application Laid-Open No. 57-158801 has an optically anisotropic axis in the plane thereof, and the direction of the optically anisotropic axis in the incident light. It has a function of reflecting a linearly polarized light component and transmitting light of a polarized light component in a direction orthogonal to the optically anisotropic axis.

The polarization splitting element 10 having such a function
4 and 108 will be described with reference to FIG.

These polarization splitting elements 104 and 108
Birefringent layer 202 having birefringence due to molecular orientation
And an isotropic layer 203 are alternately laminated. The birefringent layer 202 has an optically anisotropic axis 201 in the plane on which it is laminated. The isotropic layer 20
The refractive index of 3 is selected so as to match one of the refractive index no of ordinary light and the refractive index ne of extraordinary light of the birefringent layer 202.

Light incident on these polarization splitting elements 104 and 108 passes through the birefringent layer 202 and isotropic layer 20
3 is incident. The refractive index of the isotropic layer 203 is birefringent layer 2
02, the ordinary light component 204 of the incident light is transmitted, and a part of the extraordinary light component 205 is transmitted to the birefringent layer 202 and the isotropic layer 2.
The light is reflected by a difference in refractive index from the light reflected from the light emitting element 03. Further, since the birefringent layers 202 and the isotropic layers 203 are alternately laminated, a part of the extraordinary light is reflected in each layer, and as a result, the ordinary light component 204 is transmitted and the extraordinary light component 205 is reflected. You.
Therefore, the polarization splitting elements 104 and 108 output the extraordinary light component 2
For 05, light is reflected on the same principle as that of the dielectric thin film.

As the narrow band polarization separating element 106, FIG.
S-polarized green light was incident on the reflective liquid crystal display element 105G using a dielectric mirror having spectral characteristics as shown in FIG. Also in this narrow band polarization separating element 106, the polarizing element and D-BEF disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 57-158801 can be used by adjusting the number of layers, the layer thickness and the like. Can be used by having polarization separation characteristics. In the dielectric mirror, as shown in FIG. 3, the cutoff wavelength shifts to the longer wavelength side in P-polarized light as compared with S-polarized light. Therefore, when used in the present embodiment, only the S-polarized light component with respect to the light reflecting surface is used. Although it cannot be reflected, when an element such as the polarizing element or D-BEF is used in place of the dielectric mirror, the element itself has an optically anisotropic axis, and the Since the light in the polarization direction along can be reflected, by adjusting the angle, light in an arbitrary polarization direction can be incident according to the characteristics of the reflective liquid crystal display element 105G to be used.

These reflective liquid crystal display elements 105R, 105R,
The light incident on the light-emitting elements 05G and 105B has their polarization directions modulated in accordance with an image signal, and then the polarization separation elements 104 and 108.
Then, only the light whose polarization direction is modulated again enters the narrow-band polarization splitter 106, passes through the polarization splitters 104 and 108 and the narrow-band polarization splitter 106, and is synthesized by the cross dichroic prism 109 for color synthesis. Incident on the projection lens 110. At this time, the polarization separation element 1
The reflected light from the reflective liquid crystal display elements 105R, 105G, and 105B that have passed through the liquid crystal elements 04, 108 and the narrow-band polarization separating element 106 is P-polarized light. On the other hand, since the cross dichroic prism 109 used in the present embodiment has a spectral characteristic optimized for S-polarized light, a 、 λ plate (not shown) bonded to the light incident surface of the cross dichroic prism 109 , The polarization direction was rotated by 90 °, and incident as S-polarized light.

In this embodiment, the reflection type liquid crystal display element 10
As 5, a 1.3-inch XGA panel (1024 × 768 dots) was used. The mode of the liquid crystal is vertical alignment, and when no voltage is applied as shown in FIG. 4A, the liquid crystal molecules 402 are vertically aligned with respect to the glass substrate 401 and receive linearly polarized light. Then, the light is reflected in the same polarization state. These lights are reflected again by the polarization splitters 104 and 108 and the narrowband polarization splitter 106 and returned to the light path direction on the light source 101 side. Note that reference numeral 403 in FIG. 4A is a reflective electrode.

On the other hand, when a voltage is applied as shown in FIG. 4B, the liquid crystal molecules 402 are oriented horizontally with respect to the glass substrate 401. When linearly polarized light enters here, the polarization direction is modulated by the refractive index anisotropy of the liquid crystal.
At this time, while light reciprocates in the liquid crystal layer, the liquid crystal molecules 402
When the thickness of the liquid crystal layer (cell thickness) and Δn (the difference in the refractive index between the major axis and the minor axis of the liquid crystal molecules) are adjusted so that the phase difference of light with respect to the major axis and the minor axis becomes λλ, the reflective liquid crystal is obtained. The light reflected by the display element 105 becomes linearly polarized light rotated by 90 ° with respect to the polarization direction of the incident light, and transmits through the polarization splitters 104 and 108 and the narrow-band polarization splitter 106. As the mode of the liquid crystal, in addition to the above-described vertical alignment, any mode that uses polarization of light such as TN can be applied.

In this embodiment, in addition to the above optical components, polarizing filters 111 and 112 are arranged before and after the polarization separating elements 104 and 108 and the narrow band polarization separating element 106 to improve the contrast ratio and prevent ghost. . The transmission optical axis of the polarization filter 111 on the incident side is set parallel to the paper surface so as to cut off the P-polarized light. As a result, only the S-polarized light enters the polarization splitters 104 and 108 and the narrow band polarization splitter 106, and even if the extinction ratio of the polarization splitter is low, the reflective liquid crystal display 105
Since only S-polarized light is incident on R, 105G, and 105B, the contrast ratio is improved. This polarizing filter 11
When there is no 1, for example, the light of the green P-polarized component transmitted through the narrow-band polarized light separating element 106 is incident on the polarized light separating element 108, and this light is incident on the reflective liquid crystal display element for blue. Then, the green light is modulated according to the blue image signal and projected as a ghost. The polarization filter 112 on the emission side is arranged so that the optical axis is orthogonal to the polarization filter 111 on the incidence side. The polarizing filter 112 also has a function of preventing the occurrence of a contrast ratio and ghost on the same principle.

These polarizing filters 111 and 112 are
In the present embodiment, the polarization splitters 104 and 108 and the narrow band polarization splitter 106 are arranged on both the light incident side and the emission side. However, the effect can be obtained by disposing them on either the incident side or the emission side. Also, the incident side polarizing filters 111 and 11
It is desirable that no optical component be disposed between the light-emitting element 2 and the polarization separation elements 104 and 108 and the narrow-band polarization separation element 106. This is because the polarization state of light is disturbed by these optical components, and the effect is reduced.

When the optical system was constructed under the above conditions, a bright and high-contrast image was obtained.
The size could be reduced to about 65% as compared with the conventional projection optical system using the reflection type liquid crystal display element shown in FIG.

In this embodiment, the reflection type liquid crystal display element 10
Light that vibrates in the direction perpendicular to the paper is incident on 5R, 105G, and 105B.
In the case where a polarizing element disclosed in US Pat. No. 5,158,801 is used, it is desirable to adjust the polarization direction of incident light, such as P-polarized light, according to the characteristics of the reflective liquid crystal display element.

In this embodiment, the dichroic mirror 103 transmits red light and reflects green and blue light. However, the present invention is not limited to this, and it transmits blue light and reflects green and red light. Any combination, such as configuration, can be taken.

(Embodiment 2) FIG. 5 is a schematic diagram showing a projection type color image display device according to Embodiment 2 of the present invention. In the present embodiment, the same numbers are given to the same optical components as in the first embodiment.

The light from the light source 101 that has been converted into substantially parallel light by the parabolic mirror 102 enters the multilayer element 601.

As shown in FIG. 6, the laminated element 601 reflects light having a polarization component parallel to the optical anisotropy axis of the element only for each of the green and blue wavelength bands, and Two narrow band polarization splitters 80 that transmit light of the polarized component
In this example, two optically anisotropic axes 1 and 802 are stacked so as to be orthogonal to each other. As shown in FIG. 7, the characteristics are such that incident white light reflects green S-polarized light and blue P-polarized light whose polarization directions are orthogonal to each other and transmits other light. The two narrow band polarized light separating elements 80 constituting the laminated element 601
1, 802 are described in Japanese Patent Application Laid-Open No.
No. 158801 discloses a polarizing element and D-BEF.
And the like, and by adjusting the number of layers and the thickness of the layers so as to have polarization separation characteristics in the green and blue wavelength bands.

The light transmitted through the multilayer element 601 enters the narrow-band polarization splitting element 602 as shown in FIG.

As shown in FIG. 8, the narrow band polarization splitting element 602 has polarization dependency only on light in the red wavelength band, reflects only the red S-polarized component of the incident light, Has the function of cutting unnecessary green, blue and red P-polarized light. As in the case of the above-mentioned laminated element, the narrow-band polarized light separating element 602 uses the polarizing element or D-BEF disclosed in Japanese Patent Application Laid-Open No. 57-158801 described in the first embodiment. This can be realized by adjusting the parameters such as to have the polarization separation characteristic for the red wavelength band.

The red S-polarized light reflected by the narrow-band polarization splitter 602 is, as shown in FIG.
At 05R, the polarization direction is modulated in accordance with the image signal and reflected.

The green and blue lights reflected by the multilayer element 601 are incident on a polarization separation element 603 whose optical anisotropy axis is set perpendicular to the plane of the paper, and only green S-polarized light is reflected. The light is reflected in the direction of the liquid crystal display element 105G.

On the other hand, the blue P-polarized light transmitted through the polarization splitting element 603 is reflected by the reflection mirror 107 and then enters the polarization splitting element 604. The polarization separation element 604 has its optical anisotropy axis set horizontally with respect to the plane of the paper, and reflects blue P-polarized light in the direction of the reflective liquid crystal display element 105B.

In the present embodiment, as the polarization separating elements 603 and 604, a polarization selective reflection film DB manufactured by 3M and having polarization separation characteristics over the entire visible region.
Although EF was used, a polarizing element or the like disclosed in JP-A-57-158801 may be used. Further, it is not necessary to have polarization dependence over the entire visible light region, and any polarization separation element having a polarization separation characteristic with respect to green and blue in the polarization separation element 603 and with respect to blue in the polarization separation element 604 may be used. it can.

Further, before and after the polarization splitters 603 and 604 and the narrow band polarization splitter 602, S-polarized light and P-polarized light are changed according to the spectral characteristics of the cross dichroic prism 109 and the characteristics of optical components and reflective liquid crystal display elements. A wavelength plate for converting polarization may be inserted. In the present embodiment, 1/1 is applied to the red light incident surface of the cross dichroic prism 109.
A 2λ plate (not shown) was inserted.

For the same reason as in the first embodiment, the polarization filter 60 is provided on the light entrance / exit side of the polarization separation element 604 and the narrow band polarization separation element 602 and on the light exit side of the polarization separation element 603.
5,606 were arranged.

When the projection is configured with the above configuration, a bright and compact projection optical system can be realized as in the first embodiment.

In this embodiment, the reflective liquid crystal display element 10
Light that oscillates in the direction perpendicular to the plane of the drawing is incident on 5R and 105G, and light that oscillates in the horizontal direction is incident on the reflective liquid crystal display element 105B. The polarization direction of the incident light can be freely set, and may be rotated by 90 °.

Further, in the present embodiment, the blue and green lights are reflected by the laminated element 601. However, any combination such as a combination of green and red can be used for the reflected light.

In the first and second embodiments, the reflection type liquid crystal display elements 105R and 105B are provided with the polarization separation element 10R.
4, 108, 602, and 604 are made incident, but by arranging as shown in FIG. 9A, the transmitted light from the polarization splitters 100a and 100b can be reflected by the reflective liquid crystal display elements 105R and 105R. 105B. However, in this case, the polarization separation element 1 is adjusted to the position of the reflection type liquid crystal display elements 105R and 105B.
It is necessary to adjust the spectral characteristics of 00a and 100b. Further, in the first and second embodiments, the polarization separation element 104,
108, 603, 604 and narrow band polarization splitting element 10
Although plate-shaped ones were used as 6, 602, FIG.
A cube shape shown in (b) may be used. In this case, the optical path can be changed from air to glass or the like having a different refractive index, so that the optical distance from the projection lens 110 to the reflection type liquid crystal display elements 105R, 105G, and 105B can be shortened. Not only can the cost be reduced by downsizing the projection lens 110, but also when a dielectric mirror is used as the polarization splitting element, the performance of the element can be improved as compared with the case of a plate shape.

(Embodiment 3) FIG. 10 is a schematic view showing a projection type color image display apparatus according to Embodiment 3 of the present invention. In this embodiment, the same optical components as those in the first and second embodiments are denoted by the same reference numerals.

The light from the light source 101, which has been converted into substantially parallel light by the parabolic mirror 102, transmits light in the red wavelength band out of white light from the light source 101, and transmits light in the green and blue wavelength bands. The light enters a dichroic mirror 1103 that reflects light. The red light transmitted through the dichroic mirror 1103 enters the polarization separation element 1104, and only the S-polarized light enters the reflection type liquid crystal display element 105R.

In this embodiment, as the polarization separating element 1104, a polarization selective reflection film (Opt, manufactured by 3M) is used.
(I.Cal Film D-BEF), but a polarizing beam splitter (PBS) made of a dielectric film or a polarizing element disclosed in JP-A-57-158801 can be used.

On the other hand, the light in the green and blue wavelength bands reflected by the dichroic mirror 1103 transmits the S-polarized light in the blue wavelength band and enters the multilayer element 1105 that reflects the green S-polarized light.

As shown in FIG. 11, the laminated element 1105 has the optical anisotropy axis of the element only for each of the light in the green and blue wavelength bands as shown in FIG. The two narrow-band polarization splitters 1106G, 1106 reflect light having a polarization component parallel to the light, and transmit light having a polarization component orthogonal to the light.
106B is formed by laminating two optical anisotropy axes orthogonal to each other, and reflects or transmits green and blue light having the same polarization direction according to the direction of the optical anisotropy axis. Have been. In the present embodiment, as shown in FIG. 11, the optical anisotropy axis of the narrow-band polarized light separating element 1106G corresponding to green is perpendicular to the paper surface, and the optical width of the narrow-band polarized light separating element 1106B corresponding to blue is reduced. By setting the direction of the mechanical anisotropy axis in the horizontal direction with respect to the plane of the paper, S-polarized light in the green wavelength band is reflected, and S-polarized light in the blue wavelength band is transmitted. The light is incident on the elements 105G and 105B.

The narrow-band polarized light separating elements 1106G and 1106B constituting the laminated element 1105 are also disclosed in JP-A-57-1.
Achieved by using the polarizing element or D-BEF disclosed in US Pat. No. 5,801,801 and adjusting the number of layers and the thickness of the layers so as to have a polarization separation characteristic for a wavelength band of a corresponding color. can do.

After the polarization directions of the green and blue bands of light incident on the reflection type liquid crystal display elements 105G and 105B are modulated by the corresponding reflection type liquid crystal display elements, the green band light is converted to the laminated element. 1105, and the blue light is
The light is reflected by the light 105 and is synthesized, and is incident on a red-reflective dichroic mirror 1107. In the dichroic mirror 1107, the light in the red band reflected by the reflection type liquid crystal display element 105R and the reflection type liquid crystal display element 105R.
The light in the green and blue bands reflected by G and 105B is combined, and these lights are projected by the projection lens 110.

In the present embodiment, the polarizing filters 1108 and 1109 are arranged on the light input / output side of the polarization separating element 1104 and the multilayer element 1105 for the same reason as in the first embodiment.

When the projection optical system was configured with the above configuration, it was possible to realize a bright, high-contrast, and more compact projection than the first and second embodiments.

In this embodiment, the dichroic mirror 1
Although 103 transmits the red light and reflects the green and blue light, any combination of transmitting the blue light and reflecting the green and red light can be used.

In this embodiment, S-polarized light is made incident on the reflection type liquid crystal display elements 105R and 105B. However, the optical characteristics of the narrow band polarization separation elements corresponding to green and blue constituting the multilayer element 1105 are different. By rotating the optically anisotropic axis by 90 °, P-polarized light can also be incident. Similarly, P-polarized light can be incident on the reflective liquid crystal display element 105R. Also in this case, the same effect as when the S-polarized light is incident can be obtained.

Further, in this embodiment, the polarization directions of the reflected light from the reflective liquid crystal display elements 105G and 105B and the reflected light from the reflective liquid crystal display element 105R are the same at the position of the dichroic mirror 1107. However, when the polarization directions of these lights are orthogonal, the lights may be combined using a polarization beam splitter instead of the dichroic mirror.

(Embodiment 4) FIG. 12 is a schematic view showing a projection type color image display device according to Embodiment 4 of the present invention. In this embodiment, the same optical components as those in the first, second, and third embodiments are denoted by the same reference numerals.

The light from the light source 101, which has been converted into substantially parallel light by the parabolic mirror 102, enters the multilayer element 1301.

The laminated element 1301 has the same function as the laminated elements 601 and 1105 used in the second and third embodiments, and the optical anisotropy of the element is applied only to light in the green and blue wavelength bands. Two narrow-band polarization splitters 13 that reflect light having a polarization component parallel to the characteristic axis and transmit light having a polarization component orthogonal thereto
In this example, two optical anisotropy axes of 01G and 1301B are stacked at right angles. As shown in FIG. 7, the characteristics are such that incident white light reflects green S-polarized light and blue P-polarized light whose polarization directions are orthogonal to each other and transmits other light.

As the two narrow-band polarized light separating elements 1301G and 1301B constituting the laminated element 1301, the polarizing element disclosed in the Japanese Patent Application Laid-Open No. 57-158801 described in the first embodiment and the polarization selector manufactured by 3M Co., Ltd. It can be realized by using a reflection film D-BEF or the like and adjusting the number of layers and the thickness of the layers so as to have polarization separation characteristics in the green and blue wavelength bands.

The light transmitted through the multilayer element 1301 enters the narrow-band polarization splitting element 1302. As shown in FIG. 8, the narrow band polarization separating element 1302 has polarization dependency only on the light in the red wavelength band, reflects only the red S-polarized component of the incident light, and filters the other light. It has the property of cutting unnecessary green, blue and red P-polarized light by passing through.

The narrow-band polarized light separating element 1302 also has a structure similar to that of the laminated element 1301 described in the first embodiment.
A polarizing element disclosed in 7-158801 or a polarization selective reflection film D-BEF manufactured by 3M Co., Ltd. is used, and the number of layers and the thickness of the layers are adjusted so that the polarization separation characteristics with respect to the red wavelength band are improved. It can be realized by having it.

The red S-polarized light reflected by the narrow-band polarized light separating element 1302 is reflected by the reflective liquid crystal display element 105R with its polarization direction modulated in accordance with an image signal. The green and blue lights reflected by the multilayer element 1301 are polarized by the polarization splitting element 130 whose optical anisotropy axis is set perpendicular to the paper surface.
3, only the green S-polarized light is reflected by the reflection type liquid crystal display element 10.
Reflected in the direction of 5G, the blue P-polarized light is
03, and enters the reflective liquid crystal display element 105B.

In this embodiment, a D-BEF having a polarization splitting function in the entire visible range is used as the polarization splitting element 1303. However, a polarizing beam splitter (PBS) made of a dielectric film and Japanese Patent Application Laid-Open No. 57-158801 are used. A disclosed polarizing element or the like can be used. Further, the polarization splitting element 1303 does not need to have a polarization splitting function over the entire visible light range, but may have a polarization splitting function for incident light in a wavelength band.

After the polarization directions of the green and blue bands of light incident on the reflection type liquid crystal display elements 105G and 105B are modulated by the respective reflection type liquid crystal display elements, the green band light passes through the multilayer element 1303. The transmitted blue light is reflected by the multilayer element 1303, is synthesized, and is incident on the red reflecting dichroic mirror 1304. In the dichroic mirror 1304, the light in the red band reflected by the reflective liquid crystal display element 105R and the reflective liquid crystal display elements 105G, 105
The light in the green and blue bands reflected by B is synthesized, and these lights are projected by the projection lens 110.

In this embodiment, the narrow band polarization splitting element 13
The polarizing filters 1305 and 1306 were arranged on the light input / output side of No. 02 for the same reason as in the first embodiment.

When the projection optical system was configured with the above configuration, a bright and compact projection optical system as in the third embodiment could be realized.

In this embodiment, the laminated element 1301 transmits red light, reflects green S-polarized light and blue P-polarized light. However, any combination such as transmitting blue and reflecting green and red can be used. In addition, the polarization direction of the light used can be changed according to the characteristics of the reflective liquid crystal display device.

In the present embodiment, the S-polarized light and the P-polarized light are made incident on the reflection type liquid crystal display elements 105G and 105B, respectively. By rotating the optically anisotropic axis by 90 °, the reflective liquid crystal display elements 105G, 105G,
It is possible to change the polarization direction of light incident on each of the pixels 05B. Similarly, P-polarized light can be incident on the reflective liquid crystal display element 105R.

(Embodiment 5) FIG. 13 is a schematic view showing a projection type color image display device according to Embodiment 5 of the present invention. In the present embodiment, the same numbers are given to the same optical components as those in the first to fourth embodiments.

The light from the light source 101, which has been converted into substantially parallel light by the parabolic mirror 102, transmits light in the red wavelength band among white light from the light source 101, and transmits light in the green and blue wavelength bands. The light enters a dichroic mirror 1401 that reflects light. The red light transmitted through the dichroic mirror 1401 enters the polarization separation element 1402, and only the S-polarized light enters the reflection type liquid crystal display element 105R.

In the present embodiment, the polarized light separating element 1402 is a polarized light selective reflection film (Op Op.
Tical Film D-BEF), but a polarizing beam splitter (PBS) made of a dielectric film or a polarizing element disclosed in Japanese Patent Application Laid-Open No. 57-158801 can be used.

On the other hand, the light in the green and blue wavelength bands reflected by the dichroic mirror 1401 passes through the S-polarized light in the blue wavelength band and enters the multilayer element 1403 that reflects the green S-polarized light.

As shown in FIG. 14, the laminated element 1403 reflects light of a polarization component parallel to the optical anisotropy axis of the element only with respect to light in the green wavelength band, and A narrow-band polarization separation element 1404 that transmits a polarization component orthogonal to the sex axis and light in other wavelength ranges, and a polarization component parallel to the optical anisotropy axis of the element only for light in the blue wavelength band. Narrow band polarization separating element 1405 that reflects light and transmits polarized light components orthogonal to the optically anisotropic axis and light in other wavelength ranges
And the optical anisotropy axis of both are made parallel, and the polarization direction of the incident light is set to 90 ° between the two elements 1404 and 1405.
It has a three-layer structure in which a rotating wavelength plate 1406 is arranged, and separates green and blue lights having the same polarization direction into green and blue lights whose polarization directions are orthogonal to each other. It has a function of pointing to the elements 105G and 105B. In the present embodiment, the narrow band polarization splitting elements 1404, 1
The optical anisotropy axis of 405 was arranged perpendicular to the paper surface. Accordingly, green S-polarized light enters the reflective liquid crystal display element 105G, and blue P-polarized light enters the reflective liquid crystal display element 105B.

The narrow band polarized light separating elements 1404 and 1405 constituting the laminated element 1403 are also made of a polarizing element or D-BEF disclosed in Japanese Patent Application Laid-Open No. 57-158801 described in the first embodiment. It can be realized by adjusting the thickness and layer thickness so as to have polarization separation characteristics for green and blue wavelength bands.

The light in the green and blue wavelength ranges incident on the reflection type liquid crystal display elements 105G and 105B is modulated in the polarization direction by the respective reflection type liquid crystal display elements.
The blue light transmitted through the stacked element 1403 and the blue light
Are reflected, and are combined, and are incident on a red-reflective dichroic mirror 1407. At this time, only the P-polarized light reflected by the reflective liquid crystal display element 105G is transmitted through the narrow-band polarization splitting element 1404, and the polarization direction is rotated by 90 ° by the wave plate 1406 to become S-polarized light. On the other hand, as for the reflected light from the reflection type liquid crystal display element 105B, only the light that has become the S-polarized component is reflected by the narrow band polarization separation element 1405.

Therefore, the green and blue lights synthesized by the multilayer element 1403 are both S-polarized light. In the dichroic mirror 1407, the red band light reflected by the reflective liquid crystal display element 105R and the reflective liquid crystal display elements 105G,
The green and blue bands of light reflected at 05B are combined and projected by a projection lens.

In this embodiment, since the polarization directions of the light incident on the laminated element 1403 and the light emitted therefrom are the same, the polarized light which can be arranged only on the input / output side of the narrow band polarization separation element 1302 in the fourth embodiment. Filters 1305 and 1306
(See FIG. 12) can also be arranged on the input / output side of the multilayer element 1403, that is, as shown in FIG.
Since 08 and 1409 can be arranged, the contrast ratio can be improved as compared with the third embodiment.

When the projection optical system is configured with the above configuration, it is bright, has high contrast, and
A more compact projection optical system than the first and second embodiments can be realized.

In the present embodiment, the dichroic mirror 1
Although red light is transmitted and green and blue light is reflected at 401, any combination of transmitting blue light and reflecting green and red light can be used.

In this embodiment, the S-polarized light and the P-polarized light are incident on the reflection type liquid crystal display elements 105G and 105B, respectively. By rotating the optically anisotropic axis by 90 °, the reflective liquid crystal display elements 105G, 105G,
It is possible to change the polarization direction of light incident on each of the pixels 05B. Similarly, for the reflective liquid crystal display element 105R, the polarization direction of incident light can be changed.

Further, in the third, fourth and fifth embodiments, the reflected light from the polarization splitting element is made incident on the reflection type liquid crystal display element 105R. However, transmitted light may be incident on the reflection type liquid crystal display element 105R. The arrangement of 105G and 105B may be interchanged. However, in this case, it is necessary to adjust the spectral characteristics of the polarization separation element according to the position of the reflection type liquid crystal display element.

Also in Embodiments 3, 4, and 5, as in Embodiments 1 and 2, even if a wavelength plate for changing the polarization direction of light is inserted in accordance with the characteristics of the reflective liquid crystal display element and optical components. Further, cube-shaped devices may be used as the polarization beam splitter, the narrow band polarization beam splitter, and the color combining device. Also in this case, the optical distance from the projection lens to the reflection type liquid crystal display element can be shortened, so that the cost can be reduced by downsizing the projection lens.

[0118]

As described above, according to the present invention, in a projection using a reflection type image display device, by using an optical element having both functions of polarization separation and color separation, compared with the conventional one, The optical system can be made significantly more compact. In addition, by stacking optical elements having both functions of polarization separation and color separation, one reflection type image display element has conventionally corresponded to one polarization separation element. Two reflective image display elements can be made to correspond to the elements, and the optical system can be made more compact.

Further, by disposing a polarizing filter on the light input / output side of an optical element or a laminated element having both functions of polarization separation and color separation, generation of ghost due to leaked light or unnecessary light from the element is achieved. Can be prevented, and a good image having a high contrast ratio can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a projection type color image display device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram (cross-sectional view) of a polarization beam splitter having an optically anisotropic axis, provided in the projection type color image display device according to the first embodiment.

FIG. 3 is a diagram illustrating spectral characteristics of a narrow band polarization splitting element used in the first embodiment.

FIG. 4 is an operation explanatory view (cross-sectional view) of the reflective liquid crystal display element used in Embodiments 1 to 5;

FIG. 5 is a schematic diagram of a projection type color image display device according to a second embodiment of the present invention.

FIG. 6 is a configuration diagram (cross-sectional view) of a stacked element used in Embodiment 2.

FIG. 7 is a diagram showing the spectral characteristics of the multilayer element used in the second embodiment.

FIG. 8 is a diagram illustrating spectral characteristics of a narrow-band polarization splitter used in the second embodiment.

9 (a) and (b) show Embodiments 1 and 2, respectively.
FIG. 3 is a schematic diagram of another configuration of the projection type color image display device according to the first embodiment.

FIG. 10 is a schematic diagram of a projection type color image display device according to a third embodiment of the present invention.

FIG. 11 is a configuration diagram (perspective view) of a stacked element used in Embodiment 3.

FIG. 12 is a schematic diagram of a projection type color image display device according to Embodiment 4 of the present invention.

FIG. 13 is a schematic diagram of a projection type color image display device according to Embodiment 5 of the present invention.

FIG. 14 is a configuration diagram (cross-sectional view) of a laminated element used in a fifth embodiment.

FIG. 15 is an explanatory view (perspective view) of a pixel structure of a transmissive liquid crystal display element according to the related art.

FIG. 16 is a sectional view of a reflective liquid crystal display device to which the present invention can be applied.

FIG. 17 is an explanatory diagram of a conventional projection optical system using a reflective liquid crystal display element.

FIG. 18 is a schematic view of a conventional projection type color image display device using a reflection type liquid crystal display element.

FIG. 19 is a diagram illustrating the polarization dependence of a cross dichroic prism according to the related art.

FIG. 20 is an explanatory diagram of a problem that occurs in a cross dichroic prism according to the related art.

FIG. 21 is an explanatory diagram of a generation mechanism of stray light and ghost according to the related art.

FIG. 22 is an explanatory diagram of stray light and light that causes ghost in the related art.

FIG. 23 is an explanatory diagram of a conventional projection optical system using a transmission type liquid crystal display element.

FIG. 24 is a diagram showing spectral characteristics of a cross dichroic prism according to the related art with respect to random polarization.

FIG. 25 is a schematic diagram for explaining a ghost generation mechanism that can be solved when a polarizing filter is used in the present invention.

[Explanation of symbols]

Reference Signs List 101 light source 102 parabolic mirror 103 dichroic mirror 104 polarization separation element 105R, 105G, 105B reflection type liquid crystal display element 106 narrow band polarization separation element 107 reflection mirror 108 polarization separation element 109 cross dichroic prism 110 projection lens 111 polarization filter 112 polarization filter Reference Signs List 201 optical anisotropy axis 202 birefringent layer 203 isotropic layer 204 ordinary light component 205 extraordinary light component 401 glass substrate 402 liquid crystal molecule 403 reflective electrode 601 laminated element 602 narrow band polarized light separating element 603, 604 polarized light separating element 605 polarized light Filter 606 Polarization filter 801, 802 Narrow band polarization splitter 1103 Dichroic mirror 1104 Polarization splitter 1105 Stacking device 1106 G, 1106 B Narrow band polarization splitter 1107 Dichroic mirror 1108 Polarization filter 1109 Polarization filter 1301 Multilayer element 1301G, 1301B, 1302 Narrow band polarization separation element 1303 Polarization separation element 1304 Dichroic mirror 1305 Polarization filter 1306 Polarization filter 1401 Dichroic mirror 1402 Polarization separation element 1403 Polarization element 1404, 1405 Polarization element Separation element 1406 Wave plate 1407 Dichroic mirror 1601 TFT 1602 Black matrix 1603 Gate bus line 1604 Source bus line 1700 Pixel electrode 11 Light source 12 Polarization beam splitter 13 Cross dichroic prism 14 Reflective liquid crystal display element 15 Projection lens 16 Screen

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI G03B 21/00 G03B 21/00 D

Claims (11)

[Claims] 1. A light source comprising: a light source; and a plurality of optical elements for separating light from the light source into a plurality of lights having different wavelength bands, and transmitting or reflecting the light of each color according to a polarization direction to separate the lights. An optical unit, a reflective image display element that receives light from the optical unit and modulates a polarization direction according to an image signal, a color combining element that combines light modulated by the reflective image display element, and the color A projection device for projecting the light combined by the combining device, wherein at least one optical device of the optical device is an optical device having both functions of color separation and polarization separation. A projection type image display device characterized in that: 2. An optical element having both functions of color separation and polarization separation, the surface having a function of color separation and polarization separation in at least one wavelength band of three primary colors of red, green and blue. 2. The projection-type image display device according to claim 1, wherein the dielectric mirror reflects an S-polarized component and transmits a P-polarized component. 3. An optical element having both functions of color separation and polarization separation has an optically anisotropic axis in a plane having the functions of color separation and polarization separation, and has red, green, An optical element having a function of reflecting a linearly polarized light component parallel to the optically anisotropic axis of incident light in at least one wavelength band of three primary colors of blue and transmitting a linearly polarized light component orthogonal thereto. The projection-type image display device according to claim 1, wherein: 4. An optical element having both functions of color separation and polarization separation corresponds to a reflective image display element for green, and transmits light in at least one of blue and red wavelength bands. 4. The projection type image display apparatus according to claim 2, wherein the optical element has a polarization separation function in a green wavelength band. 5. An optical element having both functions of color separation and polarization separation, wherein at least one of the optical elements has three colors of red, green and blue.
It is a laminated element in which two elements that have a polarization separation function in one wavelength band of the primary colors and transmit light in another wavelength band are laminated with the optical anisotropy axes of the elements orthogonal to each other. The projection-type image display device according to claim 3, wherein: 6. An optical element having both functions of color separation and polarization separation, wherein at least one of the optical elements has three colors of red, green and blue.
It has a polarization separation function in one wavelength band of the primary colors,
Two elements that transmit light in other wavelength bands are three-layer laminated elements in which the optical anisotropy axis of each element is parallel and a half-wave plate is placed between both elements. The projection-type image display device according to claim 3, wherein: 7. The reflection type image display device corresponds to one of the transmitted light and the reflected light from the laminated device, and the laminated device transmits and transmits light having the same polarization direction in a wavelength band. 7. The light source according to claim 5, wherein the light is separated by reflection, each light is made incident on a corresponding reflection type liquid crystal display element, and light whose polarization direction is modulated by the reflection type image display element is synthesized. 4. The projection type image display device according to 1. 8. The light emitting device according to claim 8, wherein the stacked element includes a red light source,
6. The projection type according to claim 5, wherein the optical element has a function of separating light of three primary colors of green and blue into light of two colors whose polarization directions traveling in the same direction are orthogonal to each other and light of the remaining color. Image display device. 9. Receiving the remaining light of the three primary colors of red, green and blue other than the two colors of light separated by the laminated element and traveling in the same direction and having orthogonal polarization directions, and separated by the laminated element. Polarization splitting element having a function of selecting either one of P-polarized light and S-polarized light of the remaining one color from the remaining two lights other than the two colors, and causing the light to enter the corresponding reflection type image display device. The projection-type image display device according to claim 8, comprising: 10. A polarization filter for cutting at least one of a P-polarized component and an S-polarized component in at least one optical path of three primary colors of red, green and blue. 10. The projection type image display device according to 3, 4, 7, 8 or 9. 11. The apparatus according to claim 1, further comprising a wave plate for changing a polarization direction of light in at least one optical path of the three primary colors of red, green and blue. , 9 or 10.