JP2001222080A - Projection display device - Google Patents

Abstract

(57) [PROBLEMS] To prevent the occurrence of a ghost image based on the difference between the reflection characteristics of the S-polarized plane and the P-polarized plane of a dichroic mirror in a projection display device using a reflective liquid crystal panel and a dichroic mirror. SOLUTION: Illumination light emitted from a light source 2 is converted into S-polarized light by a polarization conversion element 6, reflected by an analysis surface 11A of a polarization beam splitter 11, and reflected by dichroic mirrors 12 and 1.
3 is incident. The blue light, the illumination light of which is selectively reflected by the mirror 12, is modulated and reflected by the reflection type liquid crystal panel 14B, and the polarization plane is rotated.
2 is incident. A ghost component generated by the mirror 12 due to the difference between the reflection characteristics of the S-polarized light and the P-polarized light is emitted from the liquid crystal panel 14B together with the incident image light.
The light emitted from the mirror 12 is detected by the splitter 11, and is incident on a filter 17 having a characteristic in which the transmittance in a band corresponding to the difference between the reflection characteristics of the S and P polarizations by the mirrors 12 and 13 is attenuated. The image light from which the ghost image has been removed is emitted from the filter 17 and projected on the screen 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection display device which forms a color image by projecting spatially modulated image light onto a screen using a reflection type liquid crystal panel.

[0002]

2. Description of the Related Art There is known a projection type display device which generates spatially modulated image light by using a reflection type liquid crystal panel, and forms a desired color image by projecting the image light on a screen. In such a projection display device, the illumination light obtained from the light source is decomposed into red, blue, and green illumination light and supplied to the corresponding reflective liquid crystal panels. The red, blue and green reflected lights reflected by these reflective liquid crystal panels are combined into one image light and projected on a screen or the like. For color separation of illumination light and color synthesis of reflected light reflected by reflective LCD panel,
It has been proposed to use a dichroic mirror.

FIG. 6 shows a configuration of an example of a projection display apparatus 100 using a reflection type liquid crystal panel according to a conventional technique. Here, FIG. 6 is a configuration diagram when the projection display device 100 is viewed from above.

For example, the discharge lamp 103 and the reflector 1
04 constitutes the light source 102. The illumination light of the white light emitted from the light source 102 is
The light amount distribution is made uniform by 5A and 105B, and the light enters the polarization conversion element 106. In the polarization conversion element 106, the polarization component of the incident illumination light is selectively transmitted, and the P polarization component is converted into the S polarization component. The illumination light emitted from the polarization conversion element 106 is
8, the light enters the polarization beam splitter 111 via the cold mirror 109 and the convex lens 110,
The illumination light of S-polarized light is selectively reflected by 1A, and the optical path is bent by 90 degrees.

As will be described later, in the polarization beam splitter 111, the P-polarized light component of the synthesized image light which is incident backwards along the optical path of the illuminating light of the emitted S-polarized light is selectively applied to the analysis surface 111A. And the S-polarized component is returned to the light source 102.

[0006] Illumination light emitted from the polarization beam splitter 111 is separated into blue, red and green component lights by dichroic mirrors 112 and 113 that selectively reflect blue and red, respectively.
The separated blue light, red light and green light are respectively incident on the reflective liquid crystal panels 114B, 114R and 114G. The reflective liquid crystal panels 114B, 114R, and 114G constitute light valves that are driven for each pixel by a video signal corresponding to a color component, and reflect illumination light incident as S-polarized light by rotating the polarization plane, Emit.

The blue light, red light and green light emitted from the reflective liquid crystal panels 114B, 114R and 114G are respectively coupled to dichroic mirrors 113 and 112.
Are combined into a combined image light, and the polarization beam splitter 1
11 is incident. As described above, the synthesized image light incident on the polarization beam splitter 111 is transmitted to the analysis surface 111A.
, The P-polarized component is selectively transmitted and emitted, and the S-polarized component is returned to the light source 102. Polarization beam splitter 111
Is projected onto a screen 116 via a projection lens 115 to form a projected image.

[0008]

In the projection type display device using the reflection type liquid crystal panel according to the above-mentioned prior art, there is a problem that a ghost image is seen in a projected image on the screen 116. Hereinafter, the cause of the occurrence of the ghost image will be considered.

As already described, the dichroic mirrors 112 and 113 receive the illumination light in which the S-polarized light component is selected by the polarization conversion element 106 and the S-polarized light component is converted into the P-polarized light component. In dichroic mirrors 112 and 113, blue,
The three components of red and green are separated and emitted to the reflective liquid crystal panels 114B, 114R and 114G, respectively, and the reflective liquid crystal panels 114B, 114R and 11G are respectively separated.
The image light reflected and emitted by 4G is reflected and transmitted in the incident direction of the illumination light.

FIG. 7 schematically shows a part of the configuration of a color separation / combination system of the projection display apparatus 100. Here, for the sake of explanation, a reflective liquid crystal panel 114B and a dichroic mirror 112 are shown as examples. Dichroic mirror 11
No. 2 is formed by depositing a dichroic film 112A and an anti-reflection coating film 112B on one and the other surfaces of the optical glass, respectively. The dichroic mirror 113 has a similar configuration. Reflective liquid crystal panel 11
Most of the image light emitted from 4B is reflected by the dichroic film 112A. This light is projected by the projection lens 115.
The light is projected onto the screen 116 by a projection optical system including

The incident angle when the image light emitted from the reflection type liquid crystal panel 114B is incident on the dichroic film 112A has a certain spread. The image light emitted from the reflective liquid crystal panel 114B and incident on the dichroic film 112A is reflected by the dichroic film 112A.
A has a wide wavelength range for the predetermined optical characteristics. As a result, incident light from the reflective liquid crystal panel 114B to the dichroic film 112A partially
2A, the light reaches the anti-reflection coating film 112B, is reflected by the anti-reflection coating film 112B, and transmits through the dichroic film 112A. Dichroic film 112
This image light transmitted through A is transmitted to the dichroic film 112A.
Is incident on the projection optical system together with the image light directly reflected.

Most of the components transmitted through the dichroic film 112A are components of the difference between the reflection bands of the S-polarized light and the P-polarized light by the dichroic film 112A. In the case of the dichroic mirror 114B that selectively reflects blue, the S
FIG. 8 schematically shows the reflection characteristics of polarized light and P-polarized light. In FIG. 7, the horizontal axis represents wavelength and the vertical axis represents reflectance. Also, (incident angle ≠ 0 degrees).

The dichroic mirror 114B is a blue region reflection mirror, and reflects light on the short wavelength side. The reflection by the dichroic film 112A shifts the S-polarized component toward the longer wavelength side (S in FIG. 8) and the P-polarized component toward the shorter wavelength side (P in FIG. 8) at the half-value wavelength. The difference between the half-value wavelengths of the S-polarized component and the P-polarized component is, for example, that the incident angle is
In the case of 5 degrees, it spreads to about 10 nm to 50 nm.

That is, the S-polarized light emitted from the polarization beam splitter 111 is incident on the dichroic film 112A and is reflected to a long wavelength component.
14B. Then, the reflection type liquid crystal panel 114
The polarization plane is rotated and reflected by B, and is incident on the dichroic film 112A. This reflective liquid crystal panel 11
The P-polarized light component of the light reflected by 4B is reflected by the dichroic film 112A only on the shorter wavelength side compared to the S-polarized light.

On the other hand, of the light emitted from the reflective liquid crystal panel 114B, the dichroic film 1
12A, that is, the dichroic film 1
In FIG. 12A, a component (hatched portion in FIG. 8) generated between the reflection bands of P-polarized light and S-polarized light (difference) passes through the dichroic film 112A as it is. The transmitted component is reflected by the anti-reflection coating film 112B and passes through the dichroic film 112A. This component produces a ghost image in the blue region.

In the red region, a ghost image is generated for the same reason. In the dichroic mirror 114R that selectively reflects red, as shown in an example in FIG. 9, the S-polarized light component at the half-value wavelength is on the short wavelength side (S in FIG. 9), and the P-polarized light component is long. It is shifted toward the wavelength side (P in FIG. 9). Therefore, even in this case, the difference between the reflection bands of the P-polarized light and the S-polarized light (FIG. 9)
A ghost image is generated based on the hatched portion of FIG.

FIG. 10 shows an example of a ghost image generated as described above. In this example, a ghost image (shown by a dotted line) is projected on the right side of the normal image shown by the solid line. This ghost image has a problem that the ghost image becomes more noticeable as the contrast performance of the projection display apparatus 100 is improved.

In order to reduce the ghost image, for example, a method of improving the performance of the dichroic film 112A and narrowing the width between the reflection bands of the S-polarized light and the P-polarized light by the dichroic film 112A can be considered. However, improving the performance of the membrane requires that the dichroic membrane 1
There is a problem that the number of layers constituting the film 12A is increased, which leads to an increase in cost.

Further, when the performance of the film is improved, there is a problem that the contrast performance is also improved and even a slight ghost image becomes noticeable.

In other words, the higher the contrast property is achieved, the more the above-mentioned ghost image becomes more conspicuous.

Accordingly, an object of the present invention is to spatially modulate illumination light color-separated by a dichroic mirror with a reflective liquid crystal panel to produce image light, and to combine image light emitted from the reflective liquid crystal panel with a dichroic mirror. In this case, it is an object of the present invention to provide a projection display device in which a ghost image is prevented from being generated based on a difference between reflectance characteristics of an S-polarized light component and a P-polarized light component in a dichroic mirror.

[0022]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention spatially modulates and reflects light composed of a first polarized light to form a plane of polarization with respect to the plane of polarization of the first polarized light. A plurality of reflection-type image forming means for emitting image light by rotating the light source; and decomposing the incident light composed of the first polarized light into wavelength components corresponding to the reflection-type image formation means and emitting the light to the reflection-type image formation means. And a color separation / combination unit that combines the image light obtained from the reflection type image forming unit and emits the light in the incident direction, and the first polarization and the polarization plane of the combined image light obtained from the color separation / combination unit are orthogonal to each other. In a projection display device including an optical system having an analyzing unit that detects light in the second polarization direction and a projecting unit that projects the combined image light detected by the analyzing unit onto a predetermined projection target, In the optical path of the optical system,
A projection type display device provided with optical filter means for removing at least a part of a light component corresponding to a difference between a spectral characteristic of the first polarized light and a spectral characteristic of the second polarized light by the color separation / combination means. It is.

As described above, the present invention spatially modulates and reflects light composed of the first polarized light, and emits image light obtained by rotating the polarization plane with respect to the polarization plane of the first polarized light. A plurality of reflection-type image forming means, and the incident light composed of the first polarized light is decomposed into wavelength components corresponding to the reflection-type image formation means and emitted to the reflection-type image formation means, and is obtained from the reflection-type image formation means. A color separation / synthesis unit that synthesizes the image light to be emitted and emits the light in the incident direction;
A projection type display device including an optical system having an analyzer for detecting light in the polarization direction of light and a projector for projecting the combined image light detected by the analyzer to a predetermined projection target. In the optical path, there is provided an optical filter means for removing at least a part of the light component corresponding to the difference between the spectral characteristic of the first polarized light and the spectral characteristic of the second polarized light by the color separation / combination means. First and second color separation / combination means
Ghost light components based on the difference in the spectral characteristics of the polarized light are prevented.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. According to the present invention, the generation of a ghost is provided by providing an optical filter in the optical path for cutting light of a component corresponding to the difference between the reflection bands of the S-polarized light and the P-polarized light by the dichroic mirror as described in the related art. To prevent

FIG. 1 shows an example of the spectral characteristics of an optical filter applicable to the present invention. According to FIGS. 8 and 9 described above, in the dichroic mirror that reflects the blue region,
The difference between the reflection bands of S-polarized light and P-polarized light is, for example, 510 nm.
In a dichroic mirror that reflects the red region, the difference between the reflection bands of the S-polarized light and the P-polarized light is, for example, 590 nm ± 10 nm (each half-value wavelength). Therefore, by providing an optical filter (referred to as a notch filter) that cuts both 510 nm ± 10 nm and 590 nm ± 10 nm in the optical path, as shown in an example in FIG. 1, the S-polarized light in the dichroic mirror and It is possible to remove a ghost light component generated due to the difference between the reflection bands of the P-polarized light.

FIG. 2 shows a configuration of an example of the projection display device 1 according to the embodiment of the present invention. For example, the light source 2 is constituted by the discharge lamp 3 and the reflector 4. Light source 2
The illumination light of the emitted white light is made uniform in the light amount distribution by the fly-eye lenses 5A and 5B, and is incident on the polarization conversion element 6. The polarization conversion element 6 calculates the S
P that selectively transmits the polarized light component and is orthogonal to the polarized light component
It is an optical element that converts a polarization component into an S-polarization component.

By using the polarization conversion element 6, for the illumination light emitted from the discharge lamp 3 with various polarization planes, the polarization component effective for image display is increased, and the polarization component orthogonal to this is changed. The illumination light is emitted in a reduced state. Thereby, the utilization efficiency of the illumination light is increased, and the contrast of the displayed image is improved.

The illumination light emitted from the polarization conversion element 6 is
The light is condensed by the convex lens 8 and is incident on the cold mirror 9. The illumination light incident on the cold mirror 9 is emitted after bending the optical path of the component excluding the infrared region by a predetermined angle, for example, 90 degrees. The illumination light emitted from the cold mirror 9 is
The light is condensed by the convex lens 10 and is incident on the polarization beam splitter 11.

The polarization beam splitter 11 is formed by bonding the inclined surfaces of two right-angle prisms to each other, and an analysis surface 11A is formed on the bonded surface. The illumination light that has entered the polarization beam splitter 11 has the S-polarized component selectively reflected by the light detection surface 11A, the optical path is bent by 90 degrees and emitted, and the P-polarized component is selectively transmitted. Illumination light emitted from the polarization beam splitter 11 is incident on dichroic mirrors 12 and 13 arranged to cross the optical path.

As will be described later, in the polarization beam splitter 11, the P-polarized light component of the synthesized image light which is incident backwards on the optical path of the illuminating light by the emitted S-polarized light is selectively applied to the analysis surface 11A. And returns the S-polarized light component to the light source 2.

The dichroic mirrors 12 and 13 are
As already described with reference to FIG. 6 in the prior art, a dichroic film formed by laminating a dielectric film on one surface of an optical glass is formed, and an antireflection coating film (A) is formed on the other surface.
R film) is formed. The dichroic mirrors 12 and 13 are formed with dichroic films MB and MR that selectively reflect blue light and red light, respectively.

On the other hand, the reflection type liquid crystal panel 14B is arranged at a position where light can enter and reflect with the dichroic mirror 12 mutually. Further, the reflection type liquid crystal panel 14
R is arranged at a position where light can be incident on and reflected from the dichroic mirror 13. Further, the light transmitted through the dichroic mirror 13 is incident on the reflective liquid crystal panel 14G, and the reflective liquid crystal panel 14G
It is arranged at a position where the light reflected by the light can enter the dichroic mirror 13.

The reflective liquid crystal panels 14B, 14R, and 14G constitute light valves that are driven for each pixel by a video signal of a corresponding color component, and modulate and emit incident light. Reflective liquid crystal panel 14B, 1
The illumination light incident on the 4R and 14G with the S-polarized plane is reflected and emitted after the polarization plane is rotated. As a result, the reflection type liquid crystal panels 14B, 14R, and 14G emit image light whose polarization plane changes in accordance with each color signal.

Therefore, the illumination light emitted from the polarizing beam splitter 11 and incident on the dichroic mirror 12 selectively reflects the blue component and is incident on the reflection type liquid crystal panel 14B. The amount of the illumination light is controlled by the reflection type liquid crystal panel 14B for each pixel to generate blue image light, and the polarization plane is rotated to be P-polarized light and emitted. On the other hand, of the illumination light incident on the dichroic mirror 12, most of the illumination light other than the blue component (red and green components) is transmitted and is incident on the dichroic mirror 13.

Similarly to the dichroic mirror 12, the dichroic mirror 13 selectively reflects red light from the incident illumination light and transmits the remaining component, that is, green component light. The red light reflected by the dichroic mirror 13 is reflected by the reflective liquid crystal panel 14R in the same manner as described above.
And is converted into red image light, and the light is emitted after rotating the plane of polarization. Similarly, the green light transmitted through the dichroic mirror 13 is also reflected by the reflective liquid crystal panel 14G.
The light is converted into green image light, and the light is emitted with its polarization plane rotated.

The green image light emitted from the reflective liquid crystal panel 14G passes through the dichroic mirrors 13 and 12, respectively. The red image light emitted from the reflective liquid crystal panel 14R is reflected by the dichroic mirror 13 and transmitted through the dichroic mirror 12. The blue image light emitted from the reflective liquid crystal panel 14G is reflected by the dichroic mirror 12. Thus, the blue image light, the red image light, and the green image light emitted from the reflective liquid crystal panels 14B, 14R, and 14G are combined by the dichroic mirrors 12 and 13 to be combined image light.

Here, the operation of the dichroic mirrors 12 and 13 will be described. First, the operation of the dichroic mirror 12 will be described. In the S-polarized light component of the illumination light reflected by the polarization beam splitter 11, a blue region component is selectively reflected by the dichroic mirror 12. Here, since the S-polarized light component is reflected, the longer wavelength component is reflected as compared with the P-polarized light component according to FIG. 8 described above. The reflected component is incident on the reflective liquid crystal panel 14B.

The illuminating light incident on the reflective liquid crystal panel 14B is reflected by rotating the plane of polarization, so that the light emitted from the reflective liquid crystal panel 14B contains a P-polarized component.
The P-polarized light component is reflected by the dichroic mirror 12 as S
There is a half-value wavelength of the reflectance on the shorter wavelength side than the polarization component. Therefore, most of the difference between the wavelength component reflected by the S-polarized component and the wavelength component of the P-polarized component of the light emitted from the reflective liquid crystal panel 14B is reduced to the dichroic mirror 12
Through the dichroic film MB formed on one surface of the substrate. The transmitted component is incident on the anti-reflection coating film formed on the other surface of the dichroic mirror 12, and is partially reflected. A ghost light component is generated by reflecting a transmission component of the dichroic film, which is caused by a difference in reflectance between the P-polarized component and the S-polarized component, on the antireflection coating film.

The same phenomenon occurs in the dichroic mirror 13. In the S-polarized light component of the illumination light reflected by the polarization beam splitter 11, a red region component is selectively reflected by the dichroic mirror 13. Here, since the S-polarized component is reflected, a shorter wavelength component is reflected as compared with the P-polarized component according to FIG. 9 described above. This reflected component is reflected by the reflection type liquid crystal panel 14R.
Is incident on.

The illuminating light incident on the reflection type liquid crystal panel 14R is reflected by rotating the plane of polarization, and thus the light emitted from the reflection type liquid crystal panel 14R contains a P-polarized component.
The P-polarized light component is reflected by the dichroic mirror 13 as S
There is a half-value wavelength of the reflectance on the longer wavelength side than the polarization component. Therefore, most of the difference between the wavelength component reflected by the S-polarized component and the wavelength component modulated and reflected by the P-polarized component passes through the dichroic film MR formed on one surface of the dichroic mirror 13. Will do. The transmitted component is made incident on the anti-reflection coating film formed on the other surface of the dichroic mirror 13 and partially reflected. A ghost light component is generated by reflecting a transmission component of the dichroic film, which is caused by a difference in reflectance between the P-polarized component and the S-polarized component, on the antireflection coating film.

The above-mentioned reflective liquid crystal panels 14B, 14
Blue image light, red image light, and green image light emitted from R and 14G are used as dichroic mirrors 12 and 1.
The synthesized image light synthesized by 3 includes these ghost light components. As described above, the synthesized image light is incident on the polarization beam splitter 11 by following the optical path of the illumination light emitted from the polarization beam splitter 11 in reverse.

The synthesized image light that has entered the polarization beam splitter 11 is selectively transmitted through the analysis surface 11A so that the P-polarized component is emitted, and is emitted from the polarization beam splitter 11.
The composite image light emitted from the polarization beam splitter 11 is incident on the optical filter 17. Optical filter 17
Is a filter having the characteristics as shown in FIG. 1 described above, and is disposed between the polarizing beam splitter 11 and the projection lens 15 so that the incident angle with respect to the optical axis is substantially 0 degrees. FIG. 3 shows a specific example of the spectral characteristics of the optical filter 17 created under predetermined conditions. In this example, 4
With a half-value wavelength of 90 nm and 580 nm, a transmittance of 10% or less is obtained in a range of ± 10 nm.

The ghost light component by the dichroic mirror 12 and the ghost light component by the dichroic mirror 13 are cut off when the synthesized image light is incident on the optical filter 17. The combined image light from which the ghost light component has been cut by the optical filter 17 is incident on the projection lens 15 and projected on the screen 16. The projection lens 15 is composed of, for example, an optical system having a plurality of lenses, and performs focus adjustment of an image projected on the screen 16.

In the above description, the dichroic mirror 12 disposed first in the optical path of the illumination light is a blue region reflection mirror, and the dichroic mirror 1 disposed later
Although 3 has been described as being a red region reflection mirror, this is not limited to this example. For example, even if the dichroic mirror 12 is a red region reflection mirror and the dichroic mirror 13 is a blue region reflection mirror, the present invention can be similarly applied using the optical filter 17 described above.

Further, the dichroic mirror 12 may be a red area reflection mirror, the dichroic mirror 13 may be a green or red-green area reflection mirror, or the dichroic mirror 12 may be a blue area reflection mirror, and may be a dichroic mirror 13 May be a blue-green region reflection mirror. In these cases, the present invention can be similarly applied using the above-described optical filter 17.

Furthermore, in the above description, the optical filter 17 is disposed between the polarization beam splitter 11 and the projection lens 15, but this is not limited to this example. The optical filter 17 may be provided on the projection lens 15.
The optical filter 17 can be disposed on any of the incident side, the inside, and the exit side of the projection lens 15. The lens itself constituting the projection lens 15 may have the characteristics of the optical filter 17 described above.

Further, in the above description, the optical filter 17
Is disposed between the polarization beam splitter 11 and the projection lens 15, but the present invention is not limited to this example. The optical filter 17 is disposed on the exit side of the polarization beam splitter 11, that is, on the projection lens 15 side. May be adhered to. As a result, the glass boundary surface in contact with the air is reduced by one, and the efficiency is improved. Of course, the output side itself of the polarization beam splitter 11 may have characteristics as the optical filter 17.

In the above description, the optical filter 17 is described as being disposed between the polarization beam splitter 11 and the projection lens 15, but the present invention is not limited to this example. That is, it can be arranged on the dichroic mirrors 12 and 13 side. Further, the optical filter 17 may be disposed on the incident side of the illumination light in the polarization beam splitter 11.

Further, in the above-described color separation / combination system including the dichroic mirror and the reflection type liquid crystal panel, an optical system in which the optical path of the incoming / outgoing light has a certain angle component with respect to the reflection type liquid crystal panel. The present invention can also be applied to the present invention. FIG. 4 shows an example of the configuration of a color separation / combination system in the configuration of a projection display device having such an optical system. In FIG. 4, the same parts as those in FIG. 1 described above are denoted by the same reference numerals, and detailed description will be omitted.

Illumination light emitted from a light source (not shown) at a slight elevation angle is incident on dichroic mirrors 12 and 13 via a polarizing plate 20B that selectively transmits S-polarized light. As described above, the dichroic mirrors 12 and 13 selectively reflect the blue component and the red component from the incident illumination light, and enter the reflection type liquid crystal panel (not shown). The illumination light (green light) transmitted through the dichroic mirrors 12 and 13 has its polarization plane rotated by the reflective liquid crystal panel 14G, and is reflected and emitted at an angle corresponding to the incident angle.

The image light emitted from the reflection type liquid crystal panel 14G is incident on the polarizing plate 20A through the dichroic mirrors 12 and 13, which selectively transmits the P-polarized component. Similarly, the illumination light reflected by the dichroic mirrors 12 and 13 has its polarization plane rotated by a reflection type liquid crystal panel (not shown) as described above, is reflected at an angle corresponding to the incident angle, is emitted, and is incident on the polarizing plate 20A. You. These image lights incident on the polarizing plate 20A are combined, emitted to a projection lens (not shown) as combined image light, and projected on a screen.

Also in such an optical system, by disposing the above-described optical filter 17 on the optical path, the reflection region of the S-polarized light component and the P-polarized light component generated by using the dichroic mirrors 12 and 13 can be obtained. The ghost light component due to the difference can be cut, and a high quality projected image can be obtained.

Next, a modification of the embodiment of the present invention will be described. In the above description, the optical filter 17 is provided on the projection lens 15 side of the polarization beam splitter 11, but this is not limited to this example. For example, in the configuration of FIG. 1 described above, the reflective liquid crystal panels 14B and 14B
An optical filter having a predetermined characteristic can be arranged for each of R. FIG. 5 shows an optical filter 17B disposed on a reflective liquid crystal panel 14B and an optical filter 1B disposed on a reflective liquid crystal panel 14R according to this modification.
7 shows an example configuration in which 7Rs are arranged. In FIG. 5, the same parts as those in FIG. 1 described above are denoted by the same reference numerals, and detailed description will be omitted.

An optical filter 17B is arranged between the dichroic mirror 12 and the reflection type liquid crystal panel 14B. The optical filter 17B includes the dichroic mirror 12
The characteristic is such that the component on the longer wavelength side than the reflectance characteristic of the P-polarized component (see FIG. 8) is not transmitted. The optical filter 17B cuts a ghost light component based on a difference in reflectance characteristics between the S-polarized light component and the P-polarized light component in the dichroic mirror 12.

Similarly, the dichroic mirror 1 is disposed between the dichroic mirror 13 and the reflection type liquid crystal panel 14R.
An optical filter 17R having a characteristic of not transmitting a component on a shorter wavelength side than the reflectance characteristic of the P-polarized light component (see FIG. 9) by No. 3 is arranged. The optical filter 17R cuts a ghost light component based on a difference in reflectance characteristics between the S-polarized light component and the P-polarized light component in the dichroic mirror 13.

As described above, by disposing the two optical filters 17B and 17R corresponding to the respective characteristics of the dichroic mirrors 12 and 13, the dichroic mirrors 12 and 13 are provided in the same manner as in the above-described embodiment.
The ghost light component generated by the difference in the reflectance characteristics can be removed.

In the above description, the optical filters 17B and 17R are connected between the dichroic mirror 12 and the reflection type liquid crystal panel 14B, respectively.
And the reflective liquid crystal panel 14R, but this is not limited to this example. For example, the optical filters 17B and 17R correspond to the reflection type liquid crystal panel 1 forming a light valve.
You may comprise on the surface of 4B or 14R. Further, the optical filters 17B and 17R can be provided on a contrast correction phase difference plate provided on each of the reflection type liquid crystal panels 14B and 14R. In the retarder itself,
The characteristics of the optical filters 17B and 17R may be provided. Further, the dichroic mirrors 12 and 13 may have the characteristics of the optical filters 17B and 17R, respectively.

In the above-described embodiments and modifications, the reflection type liquid crystal panels 14B, 14R and 14G are used as light valves, but this is not a limitation. As a light valve, other types of devices can be applied as long as the device modulates illumination light using polarized light.

[0059]

As described above, according to the present invention, when performing color separation and color synthesis using a dichroic mirror, it is possible to prevent light reflected by a surface that is not a dichroic film from being projected as a projected image. There is an effect that can be. Therefore, there is an effect that ghost light due to a difference in reflectance characteristics between the S-polarized light component and the P-polarized light component in the dichroic mirror can be removed.

In order to prevent reflected light from a surface of the dichroic mirror that is not a dichroic film, a surface on which reflected light is generated may be provided with an anti-reflection coating (AR coat). However, as the contrast ratio of the projected image of the projection display device is improved, it is necessary to enhance the anti-reflection performance of the anti-reflection coating film on the dichroic mirror. For that purpose, it is necessary to form an anti-reflection coating film by laminating many layers, which is disadvantageous in cost. Further, there is a limit in increasing the anti-reflection performance by the anti-reflection coating to the limit, and it is inevitable that a certain amount of reflected light is generated. The method according to the present invention has an effect that the light amount itself of the component causing ghost light is reduced, so that it is possible to cope with the problem with a simple anti-reflection coating.

In the dichroic mirror, S
If the dichroic film is formed so as to eliminate the difference in reflectance between the polarized light component and the P-polarized light component, the number of dichroic films increases and the cost increases. According to the present invention, there is no need to reduce the difference in reflectance between the S-polarized light component and the P-polarized light component in the dichroic mirror, so that there is an advantage that the cost is advantageous.

Further, according to the present invention, the S-polarized light component and P
If an optical filter that cuts ghost light due to the difference between the reflectance of the polarized light component and that of the polarized light component is provided after the analysis by the polarizing beam splitter, it is not necessary to consider the polarization disorder of the illumination light and the image light. This has the effect of reducing the cost and the like required for designing the device.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating characteristics of an example of an optical filter applicable to the present invention.

FIG. 2 is a configuration diagram of an example of a projection display device according to an embodiment of the present invention.

FIG. 3 is a schematic diagram illustrating a specific example of characteristics of an optical filter applicable to the present invention and created under predetermined conditions.

FIG. 4 is a schematic diagram showing an example of a configuration of a color separation / combination system in a configuration of a projection type display device having an optical system having a certain angle component in an optical path of light entering and exiting a reflective liquid crystal panel.

FIG. 5 is a configuration diagram of an example of a projection display device according to a modification of the embodiment of the present invention.

FIG. 6 is a configuration diagram of an example of a projection type display device using a reflective liquid crystal panel according to a conventional technique.

FIG. 7 is a schematic diagram illustrating a configuration forming a part of a color separation / combination system of the projection display device.

FIG. 8 is a schematic diagram schematically showing reflection characteristics of S-polarized light and P-polarized light by a dichroic film in a dichroic mirror adapted to selectively reflect blue light.

FIG. 9 is a schematic diagram schematically showing reflection characteristics of S-polarized light and P-polarized light by a dichroic film in a dichroic mirror adapted to selectively reflect red.

FIG. 10 is a schematic diagram illustrating an example of a ghost image.

[Explanation of symbols]

2 ... light source, 6 ... polarization conversion element, 8,10 ...
Convex lens, 9 cold mirror, 11 polarizing beam splitter, 11A analysis surface, 12, 13, ...
・ Dichroic mirror, 14B, 14R, 14G
・ Reflection type liquid crystal panel, 15 ・ ・ ・ Projection lens, 16 ・ ・
・ Screen, 17 ・ ・ ・ Optical filter

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H088 EA14 EA16 HA13 HA20 HA21 HA24 HA28 MA02 MA04 MA20 2H091 FA05X FA05Z FA10X FA10Z FA14X FA14Z FA26X FA26Z FA37X FA37Z FA41Z LA12 LA17 LA18 5G435 BB12 BB16 DD05 GG02 DD09

Claims (11)

[Claims] 1. A plurality of reflection-type image forming devices that spatially modulate and reflect light composed of a first polarized light and emit image light obtained by rotating the plane of polarization with respect to the plane of polarization of the first polarized light. Means for decomposing the incident light composed of the first polarized light into wavelength components corresponding to the reflection-type image forming means and emitting the wavelength component to the reflection-type image formation means, and image light obtained by the reflection-type image formation means A color separation / synthesis unit that emits light in the incident direction, and detects light in a second polarization direction in which the first polarization and the polarization plane of the combined image light obtained by the color separation / synthesis unit are orthogonal to each other. A projection type display device having an optical system having a light analyzing means for projecting the synthesized image light detected by the light analyzing means onto a predetermined projection target; By the above color separation / synthesis means Projection display apparatus characterized by being arranged an optical filter means for excluding at least a portion of the light component corresponding to the difference between the spectral characteristics of the said second polarization of the first polarization. 2. The projection type display device according to claim 1, wherein said optical filter means is disposed between said reflection type image forming means and said color separation / combination means. Display device. 3. The projection display device according to claim 1, wherein said optical filter means is disposed between said color separation / combination means and said projection means. 4. The projection display device according to claim 3, wherein said optical filter means is disposed between said light detection means and said projection means. 5. The projection display device according to claim 3, wherein said optical filter means is disposed between said color separation / combination means and said light analysis means. . 6. The projection display device according to claim 1, wherein said optical filter means is provided in said projection means including a front surface of said projection means. 7. The projection display device according to claim 1, wherein the disposed optical element has the same characteristics as the optical filter means. 8. The projection display device according to claim 7, wherein said optical element is said light detecting means. 9. The projection display apparatus according to claim 7, wherein said optical element is said projection means. 10. The projection type display device according to claim 1, wherein said analyzing means is a polarization beam splitter. 11. The projection type display device according to claim 1, wherein said analyzing means is a polarizing plate.