JP3491809B2 - Projection type image display device - Google Patents

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 specifically, it modulates light from a light source by an image display device such as a liquid crystal display device and modulates the light. The present invention relates to a projection type image display device that magnifies and projects light on a screen by a projection lens.

[0002]

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

In the latter case of the active matrix system, the MIM (metal-metal) for driving the pixel electrodes on and off.
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 element resistance in the OFF state is reduced and the electric charge charged when a voltage is applied is discharged, so that the switching element and the wiring electrode are present in the area where they are formed. The normal drive voltage is not applied to the liquid crystal part that operates, and there is a drawback that light leaks even in the black state and the contrast ratio is lowered.

Therefore, when the liquid crystal display element is a transmissive 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 to the above, it is necessary to block the light incident on the TFT 1601 by providing a black matrix 1602 as a light shielding means on a counter substrate facing the TFT substrate with a liquid crystal layer (not shown) in between. Therefore, in the case of a transmissive liquid crystal display element, in addition to the TFT 1601 having a light shielding property, the gate bus line 1603 and the source bus line 1604 as wiring electrodes, the black matrix 16 is provided.
02 also shields the light, so that the effective area of the pixel opening in the pixel section, that is, the aperture ratio becomes small.

Further, it is difficult to form these switching elements and wiring electrodes in a certain size or less due to restrictions on their electrical performance and manufacturing technology. Therefore,
The aperture ratio further decreases as the pitch of the pixel electrodes becomes smaller as the liquid crystal display element becomes finer and smaller.

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

Various systems have been proposed in which such a reflective liquid crystal display element is applied to a projection type image display device. Proposals include JP-A-4-338721 and EIAJ.
/ Semi Sponsored Electronic Display Forum 97, Lectures 3-27 to 3-32 (1997, 4,
16-18) and Japanese Patent Laid-Open No. 4-319910.

The projection type image display device proposed in Japanese Patent Laid-Open No. 4-338721 is constructed as shown in FIG. That is, the light emitted from the light source 11 is split by the polarization beam splitter (PBS) 12 into linearly polarized light components in two directions orthogonal to each other. Reference numeral 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 lights of three primary colors of R (red), G (green), and B (blue), and the lights are 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 the color separation / combination cross dichroic prism 13, transmitted through the PBS 12, and projected onto the screen 16 by the projection lens 15.

The projection type image display device of the system proposed by the electronic display forum 97 has the same basic principle as that of the above-mentioned projection type image display device of Japanese Patent Laid-Open No. 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 color combination is arranged on the projection lens 15 side of the polarization beam splitter 12. Reference numeral 18 is a reflection mirror.

Although not shown in the drawings, the projection type image display device proposed in Japanese Patent Laid-Open No. 4-319910 discloses a method using a light scattering type liquid crystal display element as a reflection type liquid crystal display element and having a Schlieren optical system. There is.

[0012]

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

In the configuration of Japanese Patent Application Laid-Open No. 4-338721, FIG.
As shown in FIG. 7, a birefringent mode reflective liquid crystal display device 14
Therefore, the polarization state of the light incident on the cross dichroic prism 13 differs by 90 ° between the forward path and the backward path. Since the cross dichroic prism 13 usually has a 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 it is combined on the return path. shift.

FIG. 19 (a) shows an example of the spectral characteristics of the reflected light of B color for S-polarized light and P-polarized light by the cross dichroic prism, and FIG. 19 (b) shows the reflection of R color by the cross dichroic prism. An example of the spectral characteristics of light with respect to S-polarized light and P-polarized light is shown.

As can be seen 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 and color reproduction range of the projection. The P-polarized light has a narrower band than the S-polarized light for each color light of
The S-polarized light has a narrower band than the polarized light.

However, as shown in FIG.
When the brightness and color reproduction range of the R and B color lights, which are restricted by the polarized light, are adjusted, the wavelength dependence on the P polarized light and the S polarized light is large, so that the S polarized light is restricted, and the bandwidth of the G colored light is shaded. It becomes narrower as shown by the arrow, and it interferes with the display of G color light and the white balance. On the contrary, when the brightness and color reproduction range of the G color light are adjusted, the same problems as those of the G color light occur with respect to the R and B color lights, as shown in FIG.

Furthermore, when there is a wavelength shift of the spectral characteristics for P-polarized light and S-polarized light, the following problems occur. As shown in FIG. 21, for example, when S-polarized light is incident on the cross dichroic prism 13, the reflection type liquid crystal display element 14R corresponding to the R color light reflects the S-polarized light of the R band reflected by the cross dichroic prism 13. (A) is incident. Then, the reflective liquid crystal display element 14R
As a result, 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 shaded light (b) shown in FIG. 22 is transmitted through the R reflecting surface of the cross dichroic prism 13 and is incident on the liquid crystal display element 14B corresponding to the B colored light. When this light is converted into 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 converted into 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 reflected.
Passes through the R reflecting surface of the cross dichroic prism 13 and enters the projection lens, and is projected as stray light or ghost on the screen.

The above-mentioned problems of stray light and ghost also appear in the light of the band of B color, and even when P-polarized light is made incident on the cross dichroic prism 13, the problem of stray light and ghost occurs by the same principle. To do.

On the other hand, in the method proposed by 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 polarization beam splitter 12, and color combination is performed by polarization. Since the cross dichroic prism 13 provided on the projection lens 15 side of the beam splitter 12 is used, the above problem does not occur. However, in FIG. 18, a block portion for performing color separation surrounded by a dotted line 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. It has a drawback that the system size becomes large as compared with 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, basically non-polarized light (random polarized light) is incident on the cross dichroic prism. The shift of the spectrum in the forward path and the backward path that occurs in the configuration does not occur. However, since the average spectrum of P-polarized light and S-polarized light with respect to the color separation surface of the cross dichroic prism is obtained, as shown in FIG. 24, the steepness at the boundary where the spectral characteristics change from transmission to reflection becomes low, and Rate is 50%
It shows a step-like characteristic in the vicinity. Therefore, R, G, B
The color purity and the light use efficiency of the are extremely reduced. In addition,
FIG. 24A shows an example of spectral characteristics of P-polarized light and S-polarized light of B-color reflected light, and FIG. 24B shows an example of spectral characteristics of P-polarized light and S-polarized light of R-color reflected light.

The present invention has been made in order to solve the problems of the prior art as described above, and is a projection type image display using a reflection type liquid crystal display device which is small in size, light in weight and capable of bright display. The purpose is to provide a device.

[0022]

A projection type image display device according to a first aspect of the present invention is characterized in that a light source and light from the light source are color-separated into a plurality of lights having different wavelength bands, and light of each color is separated. Optical means comprising a plurality of optical elements for transmitting or reflecting depending on the polarization direction to separate the polarized light, a reflection type image display element for receiving light from the optical means and modulating the polarization direction according to an image signal, and the reflection type At least one optical element of the optical means in a projection type image display device including a color synthesizing element for synthesizing light modulated by an image display element and a projection means for projecting the light synthesized by the color synthesizing element. the color separation and has both the functions of both of the polarization separation, color separation
The optical element that has both the functions of
In-plane optical anisotropy with functions of separation and polarization separation
Has an axis and has at least one wavelength in the three primary colors red, green and blue
In the band, a straight line parallel to the optical anisotropy axis of the incident light
Reflects the polarized component and is orthogonal to the optical anisotropy axis of the incident light
It has a function of transmitting a linearly polarized light component that
And which, above objects can be achieved. Starting
The projection type image display device according to claim 2 is the optical element
Is an alternating birefringent layer with birefringence and an isotropic layer.
Having a laminated multilayer structure, the birefringent layers being laminated
Refraction of the isotropic layer that has an optically anisotropic axis in the plane
The refractive index is the refractive index no of ordinary light of the birefringent layer or of extraordinary light.
Characterized by matching with either one of the refractive indices ne
It

[0023]

[0024]

In the projection type image display device according to a third aspect of the present invention, the optical element having both the functions of the color separation and the polarization separation corresponds to the reflection type image display element for green, and blue or red. Is an optical element that transmits light in at least one of the wavelength bands and has a polarization separation function in the green wavelength band.

In the projection type image display apparatus according to a fourth aspect of the present invention, at least one of the optical elements having both the functions of the color separation and the polarization separation has a wavelength of one of the three primary colors of red, green and blue. It is characterized in that it is a laminated element in which two elements having a polarization separation function in a band and transmitting light of other wavelength bands are laminated with their optical anisotropy axes orthogonal to each other.

In the projection type image display device according to a fifth aspect of the present invention, at least one of the optical elements having both the functions of the color separation and the polarization separation has one of the three primary colors of red, green and blue. Two elements having a polarization separation function in the band and transmitting light in other wavelength bands are made parallel to each other in the optical anisotropy axis, and a half-wave plate is installed between both elements. It is a laminated element having a three-layer structure.

In the projection type image display device according to claim 6 of the present invention, the reflection type image display element corresponds to one of the transmitted light and the reflected light from the laminated element, respectively.
Light having the same polarization direction is transmitted and reflected in the wavelength band by the laminated element to be separated, 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. It is characterized by synthesizing light.

According to a seventh aspect of the present invention, there is provided the projection type image display device, wherein the laminated element includes three layers of red, green and blue contained in the light source.
It is an optical element having a function of separating primary color light into two colors of light having polarization directions orthogonal to each other and propagating in the same direction, and the remaining light.

In the projection type image display device according to claim 8 of the present invention, among the lights of the three primary colors of red, green and blue, other than the lights of two colors separated by the laminated element and advancing in the same direction and having orthogonal polarization directions. Of the remaining light other than the two colors separated by the laminated element after receiving the remaining light of P.
It is characterized by having a polarization separating element having a function of selecting either polarized light and making it incident on the corresponding reflection type image display element.

According to a ninth aspect of the present invention, there is provided the projection type image display apparatus, wherein P is provided in at least one optical path of three primary colors of red, green and blue.
It is characterized in that it is provided with a polarization filter that cuts either one of the polarization component and the S polarization component.

The projection type image display device according to a tenth aspect of the present invention is characterized in that a wave plate for changing the polarization direction of light is provided in at least one optical path of the three primary colors of red, green and blue.

The operation of the present invention will be described below.

According to the structure of claim 1, in the projection type image display device using the reflection type image display element, by using the optical element having both the functions of the color separation and the polarization separation, it is possible to separate the elements so far. Since the color separation and polarization separation performed by the element can be performed simultaneously by one optical element, the brightness,
C. The number of components can be reduced without deteriorating the display characteristics such as R., and the optical system can be significantly reduced in size and cost. Further, by performing color separation and color composition by 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,
Problems such as blue color purity, white balance shift, and ghost do not occur. Also, both color separation and polarization separation
The color separation (or,
Polarization splitting) Use a device that has optical anisotropy in the plane.
Of the light incident on the reflective image display element
The polarization direction is controlled by rotating the optical anisotropy axis.
You can choose at will. Therefore, optical system and reflective image display device
According to the characteristics of the
It is a projection-type image display device that is bright, bright, and has good CR.
Can be realized. According to the configuration of claim 2,
For the required wavelength band by adjusting the number of layers and layer thickness
It can have a polarization separation characteristic.

[0035]

[0036]

According to the third aspect of the invention, the optical element having the functions of both color separation and polarization separation is made to correspond to the reflection type image display element for green, as shown in FIG. 1 described later. In the configuration, the cross dichroic prism, which is a color synthesizing unit, can transmit colors of green and reflect blue and red to perform color synthesis. As a result, in terms of green reflection, the number of layers of the dielectric film is larger than that of the blue and red reflection dielectric films, resulting in higher cost, but by adopting the structure of green transmission, the cross dichroic prism can be made inexpensive. Can be made. Further, according to this configuration, by reflecting and synthesizing red and blue lights whose wavelength bands are not continuous, it is possible to suppress light loss and stray light during color synthesizing.

According to the structure of claim 4 , the optical element having both the functions of the color separation and the polarization separation is made into a laminated element in which two optical anisotropies are orthogonalized to form a laminated element.
Since the laminated element of one sheet can perform the same function as the two elements having the functions of color separation and polarization separation, the optical system can be further downsized.

According to the structure of claim 5 , an optical element having both functions of color separation and polarization separation is arranged such that its optical anisotropy axes are parallel to each other, and a half-wave plate is provided between both elements. By providing a laminated element having a three-layer structure in which a single laminated element can perform the same function as two elements having the functions of color separation and polarization separation, the optical system is further downsized. Can be converted.

According to the sixth aspect of the invention, it is possible to eliminate the conventional configuration in which the polarization separation element and the reflection type image display element have a one-to-one correspondence. That is, by adopting this configuration, since one reflection type image display element corresponds to each of transmitted light and reflected light from one laminated element, not only the optical system can be downsized, but also Since the polarization directions of incident light on the laminated element are aligned in the same direction,
Since an inexpensive dichroic mirror that simply performs color separation can be used as an element that directs light, cost reduction can be achieved.

According to the structure of claim 7 , the laminated element separates the lights of the three primary colors of red, green, and blue contained in the light source into the lights of two colors whose polarization directions are orthogonal to each other, in the same direction. In contrast to the conventional configuration in which the polarization separation element and the reflection type image display element have a one-to-one correspondence, one polarization separation element
Since the light from the laminated element can be distributed to the two reflective image display elements, the optical system can be downsized.

According to the structure of claim 8 , three of red, green and blue are used.
The rest of the lights of the primary colors other than the lights of the two colors separated by the laminated element and having the polarization directions orthogonal to each other enter the polarization separation element that causes the remaining one color to enter the corresponding reflection type image display element. At this time, by providing this polarization separation element with a function of selecting only P-polarized light or S-polarized light of the remaining one color light, light not contributing to display can be cut, and a high contrast ratio and a ghost-free image can be obtained. Can be realized.

According to the structure of claim 9 , a polarization filter for cutting at least one of the P-polarized component and the S-polarized component with respect to at least one optical path of the three primary colors is provided. Not only can the deterioration of the contrast ratio of the projected image due to the leaked light be prevented, but the ghost that occurs according to the principle described below can be cut.

FIG. 25 shows an example of a ghost generation mechanism. When the light incident on the laminated element 1105 is linearly polarized light, the respective component light beams correspond to the corresponding reflection-type image display element 1.
When the light incident on the laminated element 1105 is natural polarized light, the light having one polarization component is
The light is incident on a different reflection type image display element instead of the corresponding reflection type image display element. For example, the reflective image display device 1
When the laminated element 1105 is set so that the green S-polarized light is incident on 4G, the green P incident on the laminated element 1105 is
The polarized light enters the reflective image display element 14B and is modulated, and then enters the screen as S-polarized light, and this light becomes a ghost.

According to the structure of the tenth aspect , a cross dichroic prism or a color separation element is provided by inserting a wave plate for rotating the polarization direction of light on the optical paths of red, green and blue.
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, it is possible to improve the light utilization rate and the color purity of red, green and blue.

[0046]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be specifically described below with reference to the drawings.

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

In this embodiment, the light source 101 is 150
A metal halide lamp with W and an arc length of 3 mm was used.
In addition to this, a halogen lamp or a xenon lamp can be used as the light source. On the back surface of the light source 101 is a parabolic mirror 102 for emitting light from the light source as substantially parallel light.
Are arranged.

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

The blue light transmitted through the narrow band polarization separation element 106 is reflected by the reflection mirror 107, and then enters the polarization separation element 108, and the polarization separation element 108 reflects only its S-polarized component on the reflection type liquid crystal display element 105B. Reflect in the direction of.

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

The polarization separation element 10 having such a function
The basic structure of Nos. 4 and 108 will be described with reference to FIG.

These polarization separation elements 104 and 108 are
Birefringent layer 202 having birefringence due to molecular orientation
And an isotropic layer 203 are alternately laminated. The birefringent layer 202 has the optical anisotropy axis 201 in the laminated plane. In addition, the isotropic layer 20
The refractive index of 3 is selected so as to match either one of the refractive index no of ordinary light and the refractive index ne of extraordinary light of the birefringent layer 202.

The light incident on these polarization separation elements 104 and 108 is transmitted through the birefringent layer 202 and isotropic layer 20.
It is incident on 3. The refractive index of the isotropic layer 203 is the birefringent layer 2
02, the ordinary light component 204 of the incident light is transmitted, and part of the extraordinary light component 205 is part of the extraordinary light component 205, and the birefringent layer 202 and the isotropic layer 2
It is reflected due to the difference in the refractive index with 03. Further, since the birefringent layers 202 and the isotropic layers 203 are alternately laminated, 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. It
Therefore, the polarization separation elements 104 and 108 are
For 05, light is reflected by the same principle as that of the dielectric thin film.

The narrow band polarization separation element 106 is shown in FIG.
Using a dielectric mirror having a spectral characteristic as shown in, S-polarized green light was made incident on the reflective liquid crystal display element 105G. Also in this narrow band polarization separation element 106, the wavelength band required by adjusting the number of layers or the layer thickness of the polarizing element or D-BEF disclosed in Japanese Patent Laid-Open No. 57-158801 described above. Can be used by having a polarization separation characteristic with respect to. In the dielectric mirror, as shown in FIG. 3, the cutoff wavelength of P-polarized light shifts to the longer wavelength side than that of S-polarized light. Although it cannot be reflected, when an element such as the polarizing element or D-BEF is used instead of the dielectric mirror, the element itself has an optical anisotropy axis, and Since it is possible to reflect the light of the polarization direction along it, by adjusting the angle, it is possible to make the light of any polarization direction incident according to the characteristics of the reflective liquid crystal display element 105G to be used.

These reflective liquid crystal display elements 105R, 1
The light incident on 05G and 105B has its polarization direction modulated in accordance with the image signal, and then is polarized by the polarization separation elements 104 and 108.
And the narrow band polarization separation element 106 again, and only the light whose polarization direction is modulated is transmitted through the polarization separation elements 104 and 108 and the narrow band polarization separation element 106, and is combined by the cross dichroic prism 109 for color combination. And enters 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 04 and 108 and the narrow band polarization separation element 106 is P-polarized light. On the other hand, since the cross dichroic prism 109 used in the present embodiment has optimized spectral characteristics for S-polarized light, a 1 / 2λ plate (not shown) attached to the light incident surface of the cross dichroic prism 109. Then, the polarization direction was rotated by 90 ° and the light was incident as S-polarized light.

In this embodiment, the reflective liquid crystal display element 10 is used.
As No. 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 aligned vertically with respect to the glass substrate 401, and linearly polarized light is incident. Then, it is reflected in the same polarization state. These lights are reflected again by the polarization splitting elements 104 and 108 and the narrow band polarization splitting element 106, and returned in the optical path direction on the light source 101 side. In addition, 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 aligned horizontally with respect to the glass substrate 401. When linearly polarized light is incident on this, the polarization direction is modulated by the anisotropy of the refractive index of the liquid crystal.
At this time, while the light travels back and forth through the liquid crystal layer, the liquid crystal molecules 402
If the liquid crystal layer thickness (cell thickness) and Δn (refractive index difference between the long axis and the short axis of the liquid crystal molecules) are adjusted so that the phase difference of light with respect to the long axis and the short axis of the liquid crystal becomes 1 / 2λ, the reflective liquid crystal The light reflected by the display element 105 becomes linearly polarized light that is rotated by 90 ° with respect to the polarization direction of the incident light, and passes through the polarization separation elements 104 and 108 and the narrow band polarization separation element 106. As the mode of the liquid crystal, in addition to the vertical alignment described above, any mode that uses polarization of light such as TN can be applied.

In the present embodiment, in addition to the above optical components, polarization filters 111 and 112 are arranged before and after the polarization separating elements 104 and 108 and the narrow band polarization separating element 106 in order to improve the contrast ratio and prevent ghosts. . The polarization filter 111 on the incident side is set so that its transmission optical axis is parallel to the paper surface so as to cut P polarized light. As a result, only the light of the S-polarized component is incident on the polarization separation elements 104 and 108 and the narrow band polarization separation element 106, and even if the extinction ratio of the polarization separation element is poor, the reflection type liquid crystal display element 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 polarization separation element 106 enters the polarization separation element 108, and this light enters the reflection type liquid crystal display element for blue. Then, the green light is modulated according to the blue image signal and projected as a ghost. The exit-side polarization filter 112 is arranged with its optical axis orthogonal to that of the entrance-side polarization filter 111. The polarization filter 112 also has a function of preventing the occurrence of a contrast ratio or a ghost based on the same principle.

These polarization filters 111 and 112 are
In this embodiment, the polarization separating elements 104 and 108 and the narrow band polarization separating element 106 are arranged on both the light incident side and the light emitting side, but the effect can be obtained even if they are arranged on either the incident side or the light emitting side. Further, the incident side polarization filters 111 and 11
It is desirable that no optical component is arranged between the second polarization beam splitter and the polarization splitting elements 104 and 108 and the narrow band polarization splitting element 106. This is because the polarization state of light is disturbed by these optical components and the effect thereof is reduced.

When the optical system is constructed under the above conditions, a bright image with good contrast can be obtained, and FIG.
Compared with the conventional projection optical system using the reflection type liquid crystal display element shown in (1), the size could be reduced to about 65%.

In this embodiment, the reflective liquid crystal display element 10 is used.
Light oscillating in the direction perpendicular to the paper surface was made incident on the 5R, 105G, and 105B.
When the polarizing element disclosed in 158801 is used, it is desirable to adjust the polarization direction of incident light according to the characteristics of the reflective liquid crystal display element such as P-polarized light.

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

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

The light from the light source 101, which is converted into substantially parallel light by the parabolic mirror 102, is incident on the laminated element 601.

As shown in FIG. 6, the laminated element 601 reflects the light of the polarization component parallel to the optical anisotropy axis of the element only for each of the light in the wavelength bands of green and blue, and orthogonally crosses it. Two narrow band polarization separation elements 80 that transmit the light of the polarized component
The optical anisotropy axes 1, 802 are orthogonal to each other and two sheets are laminated. The characteristic is that, as shown in FIG. 7, 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. Two narrow-band polarization splitting elements 80 constituting this laminated element 601
1 and 802 are the same as those described in the first embodiment.
Polarizing element and D-BEF disclosed in 158801.
And the like, and by adjusting the number of layers and the layer thickness thereof so as to have a polarization separation characteristic in the wavelength bands of green and blue.

The light transmitted through the laminated element 601 is incident on the narrow band polarization separation element 602 as shown in FIG.

As shown in FIG. 8, the narrow band polarization separation element 602 has a polarization dependence only for light in the red wavelength band, reflects only the red S polarization component of the incident light, and By transmitting the above light, it has the function of cutting unnecessary green, blue and red P-polarized light. This narrow band polarization separation element 602 also uses the polarizing element or D-BEF disclosed in Japanese Patent Application Laid-Open No. 57-158801 described in the first embodiment, and the number of layers and the layer thickness thereof are the same as the laminated element. It can be realized by adjusting, for example, so as to have a polarization separation characteristic in the red wavelength band.

The red S-polarized light reflected by the narrow band polarization separation element 602 is reflected by the reflective liquid crystal display element 1 as shown in FIG.
At 05R, the polarization direction is modulated according to the image signal and reflected.

The green and blue lights reflected by the laminated element 601 are incident on the polarization separation element 603 which has an optical anisotropy axis perpendicular to the paper surface, and only green S-polarized light is reflected. It is reflected in the direction of the liquid crystal display element 105G.

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

As the polarization separation elements 603 and 604, in the present embodiment, a polarization selective reflection film D-B manufactured by 3M Co., which has polarization separation characteristics over the entire visible range.
Although EF is used, a polarizing element disclosed in JP-A-57-158801 may be used. Further, it is not necessary to have the polarization dependence over the entire visible light, and it is possible to use as long as the polarization separation element 603 has polarization separation characteristics with respect to green and blue and the polarization separation element 604 has with respect to blue. it can.

Before and after the polarization splitting elements 603 and 604 and the narrow band polarization splitting element 602, depending on the spectral characteristics of the cross dichroic prism 109 and the characteristics of the optical components and the reflection type liquid crystal display element, S polarization and P polarization are provided. A wavelength plate that converts polarized light may be inserted, and in the present embodiment, the cross dichroic prism 109 has 1/1 on the incident surface of red light.
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 input / output side of the polarization separation element 604 and the narrow band polarization separation element 602 and the light emission side of the polarization separation element 603.
5,606 were arranged.

When the projection is constructed with the above construction, 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 is used.
Light that oscillates in the direction perpendicular to the plane of the paper is made incident on 5R and 105G, and light that oscillates in the horizontal direction is made 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 as well, blue and green light is reflected by the laminated element 601, but the reflected light may be a combination of green and red, or any other combination is possible.

In the first and second embodiments, the polarization separation element 10 is used as the reflective liquid crystal display elements 105R and 105B.
Although the reflected light from 4, 108, 602, and 604 is incident, the transmitted light from the polarization separation elements 100a and 100b is reflected by the reflective liquid crystal display element 105R, by arranging as shown in FIG. 9A. It can be configured to be incident on 105B. However, in this case, the polarization separation element 1 is aligned with the positions of the reflective liquid crystal display elements 105R and 105B.
It is necessary to adjust the spectral characteristics of 00a and 100b. Furthermore, in the first and second embodiments, the polarization separation element 104,
108, 603, 604 and narrow band polarization separation element 10
Although plate-shaped ones were used as 6, 602,
The cube shape shown in (b) may be used. In this case, since the optical path can be replaced with air from glass or the like having a different refractive index, the optical distance from the projection lens 110 to the reflective liquid crystal display elements 105R, 105G, 105B can be shortened, and therefore the cross dichroic prism 109 can be used. Moreover, not only the cost can be reduced by downsizing the projection lens 110, but also when the dielectric mirror is used as the polarization separation element, the performance of the element can be improved as compared with the case of the plate shape.

(Third Embodiment) FIG. 10 is a schematic view showing a projection type color image display device according to a third embodiment of the present invention. In this embodiment, the same numbers are given to the same optical components as those in the first and second embodiments.

The light from the light source 101 converted into substantially parallel light by the parabolic mirror 102 transmits the light in the red wavelength band of the white light from the light source 101 and transmits the light in the green and blue wavelength bands. The light enters the 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 reflective liquid crystal display element 105R.

As the polarization separation element 1104, in this embodiment, a polarization selective reflection film (Opt) manufactured by 3M Co. is used.
Although an optical film D-BEF) is used, 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 is incident on the laminated element 1105 which transmits S-polarized light in the blue wavelength band and reflects green S-polarized light.

Similar to the one used in the second embodiment, this laminated device 1105 has an optical anisotropy axis of the device only for each of the lights in the green and blue wavelength bands, as shown in FIG. Two narrow-band polarization separation elements 1106G, 1106G that reflect the light of the polarization component parallel to
106B is a laminate of two sheets of which the optical anisotropy axis is orthogonal to each other, and is configured to reflect or transmit green and blue light having the same polarization direction depending on the direction of the optical anisotropy axis. Has been done. In this embodiment, as shown in FIG. 11, the optical anisotropy axis of the narrow band polarization separation element 1106G corresponding to green is perpendicular to the paper surface, and the optical axis of the narrow band polarization separation element 1106B corresponding to blue is shown. By setting the direction of the anisotropy axis to be horizontal to the paper surface, S-polarized light in the green wavelength band is reflected, S-polarized light in the blue wavelength band is transmitted, and the corresponding reflection type liquid crystal display is provided. The light is incident on the elements 105G and 105B.

Narrow band polarization separation elements 1106G and 1106B which constitute the laminated element 1105 are also disclosed in Japanese Patent Laid-Open No. 57-1.
Realized by using the polarizing element or D-BEF disclosed in 58801 and adjusting the number of layers and the layer thickness so as to have the polarization separation characteristic for the wavelength band of the corresponding color. can do.

Light in the green and blue bands incident on the reflective liquid crystal display elements 105G and 105B is modulated in polarization direction by the corresponding reflective liquid crystal display elements, and then the light in the green band is laminated. Blue light that has passed through 1105 and is a laminated element 1
The light is reflected by 105, is combined, and is incident on the red-reflecting dichroic mirror 1107. In the dichroic mirror 1107, the light in the red band reflected by the reflective liquid crystal display element 105R and the reflective liquid crystal display element 105R.
The lights in the green and blue bands reflected by G and 105B are combined, and these lights are projected by the projection lens 110.

In this embodiment, the polarization filters 1108 and 1109 are arranged on the light input / output sides of the polarization separation element 1104 and the laminated element 1105 for the same reason as in the first embodiment.

When the projection optical system is constructed with the above-mentioned construction, a bright, high-contrast projection that is more compact than those of the first and second embodiments can be realized.

In this embodiment, the dichroic mirror 1
Although red light is transmitted and green and blue lights are reflected at 103, any combination such as blue transmission and green and red reflection can be used.

In this embodiment, the S-polarized light is made incident on the reflective liquid crystal display elements 105R and 105B, but the optical characteristics of the narrow band polarization separation elements corresponding to the green and the blue constituting the laminated element 1105 are different. P-polarized light can also be made incident by rotating the anisotropy axis by 90 °. Similarly, P-polarized light can be made 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 to each other, a polarization beam splitter may be used instead of the dichroic mirror to combine the lights.

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

The light from the light source 101, which is converted into substantially parallel light by the parabolic mirror 102, is incident on the laminated element 1301.

The laminated element 1301 has the same function as that of the laminated elements 601 and 1105 used in the second and third embodiments, and the optical anisotropy of the element is obtained only for each of the lights in the green and blue wavelength bands. Two narrow-band polarization separation elements 13 that reflect light having a polarization component parallel to the property axis and transmit light having a polarization component orthogonal to the property axis.
Two sheets of 01G and 1301B are laminated with their optical anisotropy axes orthogonal to each other. The characteristic is that, as shown in FIG. 7, 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 polarization separation elements 1301G and 1301B constituting the laminated element 1301, the polarizing element disclosed in the Japanese Patent Laid-Open No. 57-158801 described in the first embodiment and the polarization selection manufactured by 3M Co., Ltd. This can be realized by using a reflection film D-BEF and the like, and adjusting the number of layers and the layer thickness so as to have a polarization separation characteristic in the wavelength bands of green and blue.

The light transmitted through the laminated element 1301 enters the narrow band polarization separation element 1302. As shown in FIG. 8, the narrow band polarization separation element 1302 has polarization dependency only for light in the red wavelength band, reflects only the red S-polarized component of the incident light, and reflects other light. By transmitting the light, it has a characteristic of cutting unnecessary green, blue, and red P-polarized light.

This narrow band polarization separation element 1302 is also the same as the laminated element 1301 described in the first embodiment.
The polarizing element disclosed in 7-158801 and the polarization selective reflection film D-BEF manufactured by 3M Co., Ltd. are used, and the polarization separation characteristic is obtained for the red wavelength band by adjusting the number of layers and the layer thickness. It can be realized by having it.

The red S-polarized light reflected by the narrow band polarization separation element 1302 is reflected by the reflection type liquid crystal display element 105R with its polarization direction modulated according to an image signal. The green and blue lights reflected by the laminated element 1301 have polarization anisotropy elements 130 whose optical anisotropy axes are set perpendicular to the paper surface.
The liquid crystal display device 10 is a reflection type liquid crystal display device 10 in which only green S-polarized light is incident on
The blue P-polarized light reflected in the 5 G direction is polarized by the polarization separation element 13
03, and enters the reflective liquid crystal display element 105B.

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

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

In this embodiment, the narrow band polarization separation element 13 is used.
For the same reason as in the first embodiment, the polarization filters 1305 and 1306 are arranged on the light entrance / exit side of No. 02.

When the projection optical system is constructed with the above construction, a bright and compact projection optical system as in the third embodiment can be realized.

In this embodiment, the laminated element 1301 transmits red light and reflects green S-polarized light and blue P-polarized light. However, any combination such as blue transmission and green and red reflection 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 element.

Further, in this embodiment, the S-polarized light and the P-polarized light are made incident on the reflective liquid crystal display elements 105G and 105B, respectively. By rotating the anisotropy axis by 90 °, the reflective liquid crystal display elements 105G, 1
It is possible to change the polarization direction of the light incident on each of the 05B. Similarly, P-polarized light can be made incident on the reflective liquid crystal display element 105R.

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

The light from the light source 101 converted into substantially parallel light by the parabolic mirror 102 transmits the light in the red wavelength band of the white light from the light source 101 and transmits the light in the green and blue wavelength bands. It is incident on 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 reflective liquid crystal display element 105R.

As the polarization separation element 1402, in this embodiment, a polarization selective reflection film (Op manufactured by 3M) is used.
Although the optical film D-BEF) is used, a polarizing beam splitter (PBS) made of a dielectric film or a polarizing element disclosed in Japanese Patent 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 is incident on the laminated element 1403 which transmits S-polarized light in the blue wavelength band and reflects green S-polarized light.

As shown in FIG. 14, this laminated element 1403 reflects light having a polarization component parallel to the optical anisotropy axis of the element only for light in the green wavelength band, and is optically anisotropic. A narrow-band polarization separation element 1404 that transmits a polarization component orthogonal to the property 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 range. Narrow band polarization separation element 1405 that reflects light and transmits light having a polarization component orthogonal to the optical anisotropy axis and light in other wavelength regions.
And the optical anisotropy axes of the two are parallel to each other, and the polarization direction of the incident light is 90 ° between both the elements 1404 and 1405.
It has a three-layer structure in which a rotating wave 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, and a corresponding reflection type liquid crystal display. It has a function of directing to the elements 105G and 105B. In this embodiment, the narrow band polarization separation elements 1404, 1
The optical anisotropy axis of 405 was arranged perpendicular to the paper surface. Therefore, 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.

Narrow band polarization separation elements 1404 and 1405 constituting the laminated element 1403 are also the polarizing elements disclosed in JP-A-57-158801 described in Embodiment 1 and D-BEF, and the number of layers It can be realized by adjusting the layer thickness, layer thickness and the like so as to have a polarization separation characteristic in the green and blue wavelength bands.

The light in the green and blue wavelength ranges incident on the reflective liquid crystal display elements 105G and 105B have their polarization directions modulated by the respective reflective liquid crystal display elements, and then the light in the green band is
The blue light transmitted through the laminated element 1403 and the blue light is laminated element 1403.
The reflected light is combined by being reflected by and is incident on the red-reflecting dichroic mirror 1407. At this time, only the P-polarized light reflected by the reflective liquid crystal display element 105G passes through the narrow band polarization separation element 1404, and the polarization direction is rotated by 90 ° by the wave plate 1406 to become S-polarized light. On the other hand, in the reflected light from the reflective 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 combined by the laminated element 1403 are both S-polarized. In the dichroic mirror 1407, light in the red band reflected by the reflective liquid crystal display element 105R and the reflective liquid crystal display elements 105G, 1
The lights in the green and blue bands reflected by 05B are combined, and these lights are projected by the projection lens.

In the present embodiment, since the polarization directions of the light incident on the laminated element 1403 and the light emitted therefrom are aligned, the polarization 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 entrance / exit side of the laminated 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 constructed with the above construction, it is bright, has high contrast, and
A more compact projection optical system than the first and second embodiments can be realized.

In this embodiment, the dichroic mirror 1
Although 401 transmits red light and reflects green and blue light, it is possible to take any combination such as transmitting blue and reflecting green and red.

Further, 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, but the polarization separation elements corresponding to green and blue which compose the laminated element 1403 respectively. By rotating the optical anisotropy axis of 90 ° by 90 °, the reflective liquid crystal display elements 105G, 1
It is possible to change the polarization direction of the light incident on each of the 05B. Similarly, for the reflective liquid crystal display element 105R, the polarization direction of incident light can be changed.

Furthermore, in the third, fourth, and fifth embodiments, the reflected light from the polarization separation element is made incident on the reflective liquid crystal display element 105R, but transmitted light may be made incident. The arrangement of 105G and 105B may be exchanged. However, in this case, it is necessary to adjust the spectral characteristics of the polarization separation element in accordance with the position of the reflective liquid crystal display element.

Also in the third, fourth and fifth embodiments, as in the first and second embodiments, a wavelength plate for converting the polarization direction of light may be inserted in accordance with the characteristics of the reflective liquid crystal display element or the optical component. Furthermore, a cube-shaped element may be used as the polarization separation element, the narrow band polarization separation element, and the color combining element. Also in this case, the optical distance from the projection lens to the reflective 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 the projection using the reflection type image display element, by using the optical element having both the functions of polarization separation and color separation, The optical system can be made significantly compact. Further, by stacking optical elements having both functions of polarization separation and color separation, one reflection-type image display element corresponds to one polarization separation element in the past, but one lamination Two reflective image display elements can be associated with the element, and the optical system can be made compact.

Further, by disposing a polarization filter on the light input / output side of the optical element or laminated element having both the functions of polarization separation and color separation, ghosts due to leaked light or unnecessary light from the element are generated. And a good image with a high contrast ratio can be realized.

[Brief description of 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 separation element having an optical anisotropy axis, which is included in the projection type color image display device according to the first embodiment.

FIG. 3 is a diagram showing spectral characteristics of the narrow band polarization separation 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 invention.

FIG. 6 is a configuration diagram (cross-sectional view) of a laminated element used in the second embodiment.

FIG. 7 is a diagram showing a spectral characteristic of the laminated element used in the second embodiment.

FIG. 8 is a diagram showing spectral characteristics of a narrow band polarization separation element used in the second embodiment.

9 (a) and 9 (b) show Embodiments 1 and 2, respectively.
FIG. 6 is a schematic view of another configuration of the projection type color image display device according to FIG.

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

FIG. 11 is a configuration diagram (perspective view) of a laminated element used in the third embodiment.

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

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

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

FIG. 15 is an explanatory diagram (perspective view) of a pixel structure of a transmissive liquid crystal display element according to a conventional technique.

FIG. 16 is a cross-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 reflective liquid crystal display element.

FIG. 19 is a diagram showing polarization dependence of a cross dichroic prism according to a conventional technique.

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

FIG. 21 is an explanatory diagram of a generation mechanism of stray light and ghost relating to the conventional technique.

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

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

FIG. 24 is a diagram showing spectral characteristics of a conventional cross dichroic prism for randomly polarized light.

FIG. 25 is a schematic diagram illustrating a mechanism of ghost generation that can be solved when a polarization filter is used in the present invention.

[Explanation of symbols]

101 light source 102 parabolic mirror 103 dichroic mirror 104 polarization separation elements 105R, 105G, 105B reflective 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 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 polarization separation elements 603, 604 polarization separation element 605 polarization Filter 606 Polarization filters 801, 802 Narrow band polarization separation element 1103 Dichroic mirror 1104 Polarization separation element 1105 Laminated elements 1106G, 1106B Narrow band polarization separation element 1107 Dichroic mirror 1108 Polarization filter 1109 Polarization filter 1301 Lamination elements 1301G, 1301B, 1302 Narrow band polarization separation element 1303 Polarization separation element 1304 Dichroic mirror 1305 Polarization filter 1306 Polarization filter 1401 Polarization separation element 1403 Lamination element 1404, 1405 Narrow band polarization 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 Polarizing beam splitter 13 Cross dichroic prism 14 Reflective liquid crystal display element 15 Projection lens 16 Screen

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI G03B 21/00 G03B 21/00 D (56) References JP-A-8-234202 (JP, A) JP-A-11-84319 ( JP, A) JP 11-153774 (JP, A) JP 10-268234 (JP, A) JP 9-506984 (JP, A) JP 11-509331 (JP, A) (58) ) Fields surveyed (Int.Cl. ⁷ , DB name) G03B 21/00-21/30 G02F 1/13 G02F 1/1335-1/13363 G02B 27/18 G03B 33/12

Claims (10)

(57) [Claims] 1. A light source and a plurality of optical elements for color-separating light from the light source into a plurality of lights having different wavelength bands, and for transmitting or reflecting light of each color depending on a polarization direction to separate the light by polarization. An optical means, a reflection type image display element for receiving light from the optical means and modulating a polarization direction according to an image signal; a color combination element for combining the light modulated by the reflection type image display element; in the projection type image display device and a projection means for projecting the light synthesized by the synthesizing device, at least one optical element of the optical means, has both the color separation and both polarization separating function, color separation Optical element that has both functions of polarization and polarization separation
Is an in-plane optical that has the functions of color separation and polarization separation.
Has at least one of the three primary colors red, green and blue
In one wavelength band, the optical anisotropy axis of the incident light is flat
The linear anisotropy of the incident light is reflected, and the optical anisotropy of the incident light
Having the function of transmitting the linearly polarized light component orthogonal to the axis
Projection type image display apparatus according to claim. 2. The optical element is birefringent with birefringence.
It has a multilayer structure in which a folding layer and an isotropic layer are alternately laminated,
The birefringent layer has an optical anisotropy in the laminated plane.
Has an axis, and the refractive index of the isotropic layer is the ordinary ray of the birefringent layer.
Either the refractive index of no or the refractive index of extraordinary light ne
The projection image according to claim 1, characterized in that
Image display device. 3. An optical element having both functions of color separation and polarization separation corresponds to a reflection type image display element for green, and transmits light in at least one of blue and red wavelength bands. Along with, it is an optical element having a polarization separation function in the green wavelength band.
1. The projection type image display device according to item 1 . 4. At least one of the optical elements having both the functions of color separation and polarization separation has at least one of red, green and blue.
It is a laminated element in which two elements having a polarization separation function in one wavelength band of the primary colors and transmitting light in the other wavelength bands are laminated with their optical anisotropy axes orthogonal to each other. The projection-type image display device according to claim 1 . 5. At least one of the optical elements having both the functions of the color separation and the polarization separation has at least one 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 should be a three-layer laminated element in which the optical anisotropy axes of each element are parallel and a half-wave plate is placed between both elements. The projection type image display device according to claim 1 . 6. The reflection-type image display element corresponds to each of the transmitted light and the reflected light from the laminated element, and the laminated element transmits light having the same polarization direction in a wavelength band. separated by reflecting, dissipate incident respective light to the corresponding reflective liquid crystal display device, according to claim polarization direction, characterized in that synthesizing the light modulated by the reflection type image display element 4 or 5 The projection type image display device according to. 7. The red light contained in the light source,
The projection element according to claim 4 , which is an optical element having a function of separating light of three primary colors of green and blue into light of two colors having polarization directions orthogonal to each other and traveling in the same direction, and the remaining light. Image display device. 8. The remaining light other than the lights of the three primary colors of red, green, and blue, which are separated by the laminated element, and which travel in the same direction and have two orthogonal polarization directions, are received and separated by the laminated element. Polarization separation element having a function of selecting one of P-polarized light and S-polarized light of the remaining one color from the remaining lights other than the selected two colors and causing the light to enter the corresponding reflection-type image display element. The projection type image display device according to claim 7 , further comprising: 9. red, green, at least one of the optical paths of the three primary colors of blue, claim, characterized in that it comprises a polarizing filter for cutting either the P-polarized light component or S-polarized light component 1,3 , 6, 7 or 8 is a projection type image display device. 10. A red, green, at least one of the optical paths of the three primary colors of blue, claim, characterized in that it comprises a wave plate for changing the polarization direction of the light 1,3,6,7,8 or 9 The projection type image display device according to.