JP2003185963A - Picture display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a picture display device which has small, lightweight and easily manufacturable constitution and displays a bright picture by improving the utilization efficiency of light. <P>SOLUTION: The device is provided with a flat dichroic mirror 3b on a first region of which a light flux from a light source 1 is made incident, a first reflection type spatial optical modulation element 4B on which a first color element light flux reflected on the dichroic mirror 3b is made incident, a second reflection type spatial optical modulation element 4R on which a second color element light flux which the dichroic mirror 3b transmits is made incident. The first modulated light reflected on the first reflection type spatial optical modulation element 4B and the second modulated light reflected on the second reflection type spatial optical modulation element 4R are synthesized in a second region of the dichroic mirror 3b and display a picture via a image forming optical system 5. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device having a spatial light modulation element driven according to a video signal and displaying an image by a light flux passing through the spatial light modulation element.

[0002]

2. Description of the Related Art Conventionally, an image display device having a reflective spatial light modulator has been proposed. Then, as the reflective spatial light modulator, there has been proposed one that is composed of a polarization modulator and a polarization separator.

A liquid crystal element has been proposed as a polarization modulator. This liquid crystal element includes an active matrix substrate in which a switching element such as a thin film transistor and a pixel electrode whose potential is controlled by the switching element are formed on a semiconductor substrate, a common electrode film formed in a thin film on a transparent substrate such as a glass substrate, and the active element. It consists of a liquid crystal layer sealed between a matrix substrate. In this liquid crystal element, the potential difference between the common electrode and each pixel electrode is changed for each pixel electrode in accordance with an image signal to control the alignment of the liquid crystal, thereby modulating the polarization state of incident light. The pixel electrode of the active matrix substrate is formed as a reflection electrode or an electrode for controlling the alignment of the liquid crystal via a dielectric mirror film or the like.

Spatial light modulation (intensity modulation) is performed by passing the light beam that has passed through such a polarization modulation element through a polarization separation element. That is, in the reflected light from such a polarization modulation element, a specific polarization component is changed to a different polarization component depending on the degree of orientation control of the liquid crystal that is the polarization modulation layer. Image information can be displayed by separating this polarization component by a polarization separation element. A projection type image display device is one in which reflected light from such a reflection type spatial light modulation element is used as projection light and is enlarged and projected onto a screen or the like by a projection optical system.

As a conventional image display device, as shown in FIG. 14, a device using a polarization beam splitter (PBS) 101 as a polarization separation element has been proposed. In this image display device, the light flux Ls emitted from the illumination optical system 102 enters a polarization beam splitter 101 which is a polarization separation element. This polarization beam splitter 10
In No. 1, only the P-polarized component is reflected by the reflective film and enters the dichroic prism 104. The light beam incident on the dichroic prism 104 is divided into the light beam splitting surfaces 104b, 10b in the dichroic prism 104.
By 4g, light beams Lr (red light beam), Lg (green light beam), and Lb (blue light beam) of each color are split. These color light fluxes Lr, Lg, Lb are incident on the reflection type polarization modulation elements 105R, 105G, 105B corresponding to the respective colors,
The polarization state is modulated and reflected by these polarization modulation elements 105R, 105G, and 105B. Polarization modulator 1
Each of the color-modulated light fluxes Lr, Lg, Lb reflected by 05R, 105G, 105B are polarized light modulation elements 105R, 1R.
The light is traced in a path opposite to that of the incident light to the rays 05G and 105B, is combined, and is incident on the polarization beam splitter 101 again. At this time, only the S-polarized component passes through the reflection film of the polarization beam splitter 101 and enters the projection optical system 106. Each color-modulated light flux incident on the projection optical system 106 is
An image is displayed by being projected on a screen (not shown).

Further, this image display device, as shown in FIG. 15, has the above-mentioned rectangular dichroic prism 104.
Instead of this, a dichroic prism 107 having a configuration in which wedge prisms are attached may be used.

Conventionally, for example, Japanese Patent Laid-Open No. 9-189.
As described in Japanese Patent Publication No. 809, an image display apparatus configured without using a polarization beam splitter as a polarization separation element has also been proposed.

In this image display device, as the polarization separation element, the incident light beam is diffracted and separated, and the diffracted and separated light of each wavelength band is formed on the polarization modulation element.
It is configured by using a polarization separation type diffractive optical element (holographic color filter) that selectively focuses light at a position corresponding to each pixel of (red), G (green), and B (blue). In this image display device, the illumination light flux incident on the polarization separation type diffractive optical element and the light flux reflected by the polarization modulation element and emitted from the polarization separation type diffractive optical element are:
Since they are not on the same optical axis, a color separating / combining element such as a polarization beam splitter is unnecessary.

[0009]

By the way, in the image display device having the polarization beam splitter as described above, the utilization efficiency of light in the polarization beam splitter is lowered, and a bright projection image is obtained. Is difficult. Further, the use of the polarization beam splitter makes it difficult to reduce the weight of the optical system and also makes it difficult to reduce the cost.

In such an image display device, since the incident light flux that is vertically incident on the polarization modulation element is reflected by the polarization modulation element and follows the same path as the incident light flux, the polarization beam splitter It is essential to split the incident light flux and the reflected light flux.

Further, in the image display device constituted by using the polarization separation type diffractive optical element (holographic color filter), the selective diffraction and light collection in this polarization separation type diffractive optical element are caused by the wavelength dispersion of the hologram. Therefore, it can be performed only in a very narrow wavelength range. Therefore, in this image display device, a dichroic mirror or the like is arranged in the preceding stage of the polarization separation type diffractive optical element, and it is necessary to significantly cut components of a wavelength region unfavorable to diffraction and focusing from an incident light beam, Light utilization efficiency is poor.

Further, in this image display device, in order to accurately collect a predetermined light beam on each fine color pixel and prevent crosstalk with an adjacent pixel, the illumination light beam is directed to the polarization separation type diffractive optical element. Must be incident almost parallel. Therefore, it is difficult to improve the light utilization efficiency.

Further, this polarization separation type diffractive optical element is
Since it has a lens function, in order to focus the diffracted and dispersed light flux on each desired color pixel, the positions must be accurately aligned, which makes it difficult to manufacture the device.

Therefore, the present invention has been proposed in view of the above-mentioned circumstances, and it is possible to reduce the size and weight of the device and to facilitate the manufacture, but at the same time, the light utilization efficiency is good.
An object is to provide an image display device capable of displaying a bright image.

[0015]

In order to solve the above-mentioned problems, an image display apparatus according to the present invention is provided with a light source and a plate-shaped color separation / combination element in which a light beam from this light source is incident on a first region. And a first reflective spatial light modulator on which the light flux of the first color component reflected by the color separation / combination element is incident, and a light flux of the second color component transmitted through the color separation / combination element. And a second reflective spatial light modulator.

In this image display device, the first modulated light reflected by the first reflective spatial light modulator and the second modulated light reflected by the second reflective spatial light modulator. Means that the first modulated light is incident on the second region of the color separating / combining element, the first modulated light is reflected by the color separating / combining element, and the second modulated light is transmitted through the color separating / combining element. It is characterized in that an image is displayed through the imaging optical system.

Further, the image display device according to the present invention includes a light source, a flat plate-shaped first color separation / combination element on which a light flux from the light source is incident on the first region, and a first color separation / combination element. The first reflection-type spatial light modulation element on which the light flux of the first color component reflected by and the light flux transmitted through the first color separation / combination element are incident on the first region. The second color separation / combination element, the second reflective spatial light modulation element on which the light flux of the second color component reflected by the second color separation / combination element is incident, and the second color separation / combination element. The third reflective spatial light modulator on which the transmitted light flux of the third color component is incident.

In this image display device, the second modulated light reflected by the second reflective spatial light modulator and the third modulated light reflected by the third reflective spatial light modulator. Means that the second modulated light is incident on the second region of the second color separation / combination element, the second modulated light is reflected by the second color separation / combination element, and the third modulated light is converted into the second color. The first color-modulated light that has been synthesized by transmitting through the separating / combining element and reflected by the first reflective spatial light modulating element, and the second color separation through the second and third reflective spatial light modulating elements The light flux combined in the combining element is incident on the second region of the first color separation / combination element, the first modulated light is reflected by the first color separation / combination element, and the light flux is The image is displayed through the image forming optical system after being combined by passing through the color separation / combination element 1. And wherein the door.

Further, the image display device according to the present invention includes a light source and a plurality of flat plate-like members which are arranged in a layered manner with a gap therebetween and in which light fluxes from the light source are sequentially transmitted and made incident on the first region. A sheet of color separation / combination elements and a plurality of reflective spatial light modulators arranged corresponding to the respective color separation / combination elements and into which the luminous flux of the color light component reflected by each color separation / combination element is incident. .

In this image display device, the respective modulated lights reflected by the respective reflective spatial light modulators are made incident on the second regions of the corresponding color separation / combination devices and reflected, and the corresponding color separations are performed. The second region of the color separating / combining element on the light source side of the combining element is sequentially transmitted and combined, and an image is displayed through the imaging optical system.

[0021]

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

The image display apparatus according to the present invention has an illumination optical system 1 as a light source, as shown in FIG.

Illumination luminous flux Ls emitted from the illumination optical system 1.
Is reflected by the mirror 2 and is incident on the first region of the first dichroic mirror 3b which is the flat plate-shaped first color separation / combination element. At this time, the blue component of the illumination light flux Ls is reflected by the first dichroic mirror 3b, and as the light flux Lb1 of the first color component, the polarization separation type diffractive optical element constituting the first reflective spatial light modulation element 4B. Element H
incident on b.

The other components of the illumination light flux Ls are
The light passes through the first dichroic mirror 3b and enters the first region of the second dichroic mirror 3g that is the second color separation / combination element. Here, the green component of the incident light flux is reflected by the second dichroic mirror 3g, and as the light flux Lg1 of the second color component, the polarization separation type diffractive optical element Hg constituting the second reflective spatial light modulation element 4G. Incident on.

The other component of the incident light flux, that is, the light flux Lr1 of the third color component which is the red component is transmitted through the second dichroic mirror 3g to form a third reflective spatial light modulator 4R. It is incident on the polarization separation type diffractive optical element Hr.

Each reflective spatial light modulator 4B, 4G, 4R
In, the luminous fluxes Lb1, Lg1, Lr1 of the respective color components are
When incident on the corresponding polarization separation type diffractive optical elements Hb, Hg, Hr, the P (or S) polarization component, which is the polarization component having the maximum diffraction efficiency, is diffracted, and each reflection type spatial light modulator 4B. , 4G, 4R incident on the polarization modulation elements (liquid crystal modulation layers) substantially vertically. The P (or S) polarization component incident on the polarization modulation element becomes an S (or P) polarization component according to the degree of modulation in the polarization modulation element, and is reflected by the reflection layer in this polarization modulation element. And re-enters the polarization separation type diffractive optical elements Hb, Hg, and Hr. The polarization separation type diffractive optical elements Hb, Hg and Hr are P
Since the (or S) polarization component is mainly diffracted, the S (or P) reflected from the polarization modulation element is reflected.
The polarization components are polarization separation type diffractive optical elements Hb, Hg, Hr.
Except for the diffraction efficiency which S has for the S (or P) polarization component, the polarization separation type diffractive optical elements Hb, Hg,
Permeate Hr. In this way, the modulated lights Lb2, Lg2 transmitted through the polarization splitting type diffractive optical elements Hb, Hg, Hr.
Lr2 is incident on the second regions of the corresponding dichroic mirrors 3b and 3g.

The second modulated light Lg2 reflected by the second reflective spatial light modulator 4G and the third modulated light Lr2 reflected by the third reflective spatial light modulator 4R are
The second modulated light Lg2 is incident on the second region of the second dichroic mirror 3g, is reflected by the second dichroic mirror 3g, and the third modulated light Lr2 is transmitted through the second dichroic mirror 3g. Is synthesized by.

The first modulated light Lb2 reflected by the first reflective spatial light modulator 4B, and the second dichroic mirror 3g through the second and third reflective spatial light modulators 4G and 4R. The light flux combined in the first dichroic mirror 3b is incident on the second region of the first dichroic mirror 3b,
The modulated light Lb2 is reflected by the first dichroic mirror 3b, and the light flux is transmitted through the first dichroic mirror 3b to be combined.

Each modulated light Lb thus synthesized
2, Lg2, Lr2 are incident on the projection optical system 5 as a color projection light beam Lt. The projection optical system 5 forms an image of the incident color projection light beam Lt on a screen (not shown) to display an image.

Next, the structure of the polarization splitting type diffractive optical element which constitutes the reflection type spatial light modulating element will be described. This polarized light separation type diffractive optical element is
ersed Liquid Crystal "(hereinafter referred to as" H-PDLC ").

This "H-PDLC" has glass substrates 6 and 7, as shown in FIG.
A mixed material Z including a liquid crystal, an acrylic monomer, an initiator, and a dye is filled in between. The composition of the mixed material Z described above is only an example, and other materials may be mixed depending on the application.

The formation of "H-PDLC" is performed by holographic interference fringe exposure using a laser beam. That is, as shown in FIG. 3, a mixed material (“H-PDL” having a thickness of about 5 μm is filled between the glass substrates 6 and 7).
The “C” material) Z is irradiated with coherent laser beams L1 and L2, and interference fringes (continuous light and dark stripes of light) F are generated in the mixed material Z due to the interference of two light fluxes. Then,
In the bright part of this interference fringe, the sensitive dye absorbs light while interacting with the initiator, and the polymerization of the monomer begins. As the monomer polymerizes, it gradually becomes more concentrated and dense, resulting in the migration of the monomer from the dark to the bright part of the interference fringes. As a result, in the mixed material Z, as shown in FIG. 4, a layer structure is formed by a region containing a large amount of polymerized monomers (polymer layer 8) and a region containing a large amount of liquid crystals (liquid crystal layer 9). To be done.

In the two regions 8 and 9 thus formed, a difference in the refractive index occurs due to the difference in the density and the structural difference between the polymer and the liquid crystal. Therefore, this "H-
“PDLC” is configured as a refractive index modulation type diffractive optical element. At this time, the liquid crystal has a property of being aligned perpendicularly to the boundary with the adjacent polymer layer.

In such a refractive index modulation type diffractive optical element, the diffraction efficiency is determined by the amplitude Δn of the refractive index distribution formed in a lattice shape, and the smaller Δn, the lower the diffraction efficiency.

Then, as shown in FIG. 5, "H-PDL
When light is incident on the “C” from the direction of I1, the difference Δns, which is the difference between the refractive index of the liquid crystal and the refractive index of the polymer with respect to the short axis of the incident light, is very small.
Diffraction efficiency is very small, and most of it is "HP
The transmitted light Is is transmitted through the DLC.

On the other hand, for the P-polarized component of the incident light, since the difference Δnp, which is the difference between the refractive index of the liquid crystal with respect to the long axis and the refractive index of the polymer, is large, the diffraction efficiency is high and most of the diffracted light is diffracted by the diffraction grating. It becomes the light Ip.

When the thickness of the diffraction grating is 5 μm, Δ
It is desirable that ns is 0.01 or less, and Δnp is between 0.04 and 0.1. In addition, this numerical value is an example,
Depending on the alignment direction of the liquid crystal and the refractive index of the polymer, it can be formed as a polarization separation type diffractive optical element that maximizes the diffraction efficiency of S-polarized light.

The "H-PDL" used as the polarization splitting type diffractive optical element in the image display device shown in FIG.
C ”(polarization separation type diffractive optical element Hb, Hg, Hr) is
For example, it has the spectral diffraction efficiency shown in FIGS. The diffraction efficiency of the polarized light separation type diffractive optical element Hr for red is maximized in the vicinity of the wavelength of 615 nm. The diffraction efficiency of the polarized light separation type diffractive optical element Hb for green is maximized near the wavelength of 545 nm. The diffraction efficiency of the blue polarization separation type diffractive optical element Hg is maximized near the wavelength of 455 nm.

These polarization separation type diffractive optical elements Hb, H
The g and Hr are designed so that the diffraction efficiency becomes large when a light beam having the central wavelength of the light beam entering each is incident at an incident angle of 60 ° and diffracted light is emitted at an emission angle of 180 °. Further, Δnp at this time is 0.05, Δns
Is set to 0.01.

Next, the image display device according to the present invention is shown in FIG.
As shown in FIG.
It is also possible to provide the polarizer 10 to which the illumination light flux Ls from is incident and the analyzer 11 to which the color projection light flux Lt synthesized through the respective reflection type spatial light modulation elements 4B, 4G and 4R is incident. In this case, each reflective spatial light modulator 4
In B, 4G, and 4R, the polarization component in the unnecessary direction is removed by the polarizer 10 in advance, and the polarization component in the unnecessary direction in the image display is removed by the analyzer 11, so that an image with better image quality is displayed. You can

The image display apparatus according to the present invention is shown in FIG.
As shown in FIG. 0, in the above-described image display device, the space between each reflective spatial light modulator 4B, 4G, 4R and each dichroic mirror 3b, 3g is filled with a medium such as glass having a refractive index of 1 or more. The dichroic prism 12 in the state may be arranged and configured.

Further, as shown in FIG. 11, the image display device according to the present invention may be provided with a dichroic mirror 13, which is a color separation element, separately from the dichroic mirror in the above-mentioned image display device. In this image display device, the illumination light flux emitted from the illumination optical system 1 is
It is incident on the dichroic mirror 13, and in this dichroic mirror 13, the light flux L of the red component and the blue component
s1 is reflected, and the green component light flux Ls2 is transmitted.

The red and blue light fluxes Ls1 enter the dichroic mirror 3b which is the first color separation / combination element. In the dichroic mirror 3b, the blue component light beam Lb1 of the light beam Ls1 is reflected and enters the polarization separation type diffractive optical element Hb of the first reflective spatial light modulation element 4B. The remaining component of the light flux Ls1, that is,
The red component light flux Lr1 passes through the dichroic mirror 3b and enters the polarization separation type diffractive optical element Hr of the second reflective spatial light modulator 4R.

On the other hand, the green component light beam Lg1 transmitted through the dichroic mirror 13 is incident on the polarization separation type diffractive optical element Hg of the third reflective spatial light modulation element 4G via the two mirrors 2 and 14.

Each reflective spatial light modulator 4B, 4R, 4G
The light beams Lb1, Lr1, and Lg1 incident on the polarization separation type diffractive optical elements Hb, Hr, and Hg are polarization components that maximize the diffraction efficiency in each polarization separation type diffractive optical element Hb, Hr, and Hg. S) The polarized light is diffracted and is incident on the liquid crystal modulation layers (polarization modulation elements) of the reflection type spatial light modulation elements 4B, 4R and 4G substantially vertically. The P (S) polarization component incident on each liquid crystal modulation layer becomes an S (P) polarization component according to the degree of modulation in this liquid crystal modulation layer, and is reflected by the reflection layer in the reflection-type spatial light modulation element to generate polarized light. Re-enters the separation type diffractive optical elements Hb, Hr, and Hg. These polarization separation type diffractive optical elements Hb, Hr, Hg mainly diffract the P (S) polarization component. Therefore, as for the S (P) polarization component generated by the modulation in the liquid crystal modulation element, each polarization separation type diffractive optical element Hb, Hr, Hg is S.
(P) Each polarization separation type diffractive optical element Hb, Hr, Hg is transmitted as it is, except for the diffraction efficiency for the polarization component.

In this way, the modulated light beams Lb2, which have passed through the respective polarization separation type diffractive optical elements Hb, Hr, Hg as they are,
Lr2 and Lg2 are incident on the first and second dichroic mirrors 3b and 3g to be combined. That is, the modulated light beam Lr2 reflected from the second spatial light modulation element 4R is incident on the second dichroic mirror 3g and transmitted through the second dichroic mirror 3g, and is reflected from the third spatial light modulation element 4G. The modulated light flux Lg2 thus generated is the second
The modulated light fluxes Lr2 and Lg2 are combined and incident on the first dichroic mirror 3b by being incident on the dichroic mirror 3g and reflected by the second dichroic mirror 3g.

In the first dichroic mirror 3b, the modulated light beam Lb2 reflected from the first reflective spatial light modulator 4B is incident and reflected, and at the same time, the second and third reflective spatial light modulators. The modulated light fluxes Lr2 and Lg2 from 4R and 4G are incident on and transmitted through the modulated light fluxes Lb2 and Lr.
The light fluxes obtained by combining 2, Lg2 are combined.

In this way, each of the modulated light beams Lb2, Lr
The color projection light Lt composed of 2, Lg2 is incident on the projection optical system 5. The projection optical system 5 forms an image of the incident color projection light beam Lt on a screen (not shown) to display an image.

As shown in FIG. 12, the image display device according to the present invention may be configured to have one color separation / combination element and two reflection type spatial light modulation elements. . That is, in this image display device, the illumination light flux Ls emitted from the illumination optical system 1 is reflected by the mirror 2 and enters the first region of the dichroic mirror 3 which is a flat plate color separation / combination element. At this time, the illumination luminous flux L
The blue component of s is reflected by the dichroic mirror 3 and enters the polarization separation type diffractive optical element Hb that constitutes the first reflective spatial light modulation element 4B as the light flux Lb1 of the first color component.

The other components of the illumination light flux Ls are
The light fluxes Lr1 and Lg1 transmitted through the dichroic mirror 3 are converted into the light fluxes Lr1 and Lg1 of the second and third color components.
After passing through the color wheel C1 that transmits g1 in a time-division manner, the light is incident on the polarization splitting type diffractive optical elements Hr and Hg forming the second reflective spatial light modulating element 4RG. The second reflective spatial light modulation element 4RG is a modulation element that performs modulation on the red component light flux and modulation on the green component light flux in a time division manner in synchronization with the color wheel C1.

In each of the reflection type spatial light modulators 4B and 4RG, when the luminous fluxes Lb1, Lg1 and Lr1 of the respective color components are incident on the corresponding polarization separation type diffractive optical elements Hb, Hr and Hg, the respective diffraction efficiency becomes maximum. The P (or S) polarization component, which is the polarization component, is diffracted and is incident on the polarization modulation elements (liquid crystal modulation layers) of the reflective spatial light modulation elements 4B and 4RG substantially vertically. The P (or S) polarization component incident on the polarization modulation element becomes an S (or P) polarization component according to the degree of modulation in the polarization modulation element, and is reflected by the reflection layer in this polarization modulation element. And re-enters the polarization separation type diffractive optical elements Hb, Hg, and Hr.
Since the polarization separation type diffractive optical elements Hb, Hg, Hr mainly diffract the P (or S) polarization component, the S (or P) polarization component reflected from the polarization modulator is polarized. The separation type diffractive optical elements Hb, Hg, Hr are S (,
Alternatively, the polarized light separation type diffractive optical elements Hb, Hg, and Hr are transmitted except for P) the diffraction efficiency of the polarized light component. In this way, the polarization separation type diffractive optical element Hb,
Modulated light Lb2, Lg2, Lr2 transmitted through Hg and Hr
Is incident on the second region of the corresponding dichroic mirror 3. The red component modulated light beam Lr2 and the green component modulated light beam Lg2 are incident on the dichroic mirror 3 in a time division manner.

The first modulated light Lb2 reflected by the first reflective spatial light modulator 4B and the second modulated light Lr2, L reflected by the second reflective spatial light modulator 4RG.
g2 is incident on the second region of the dichroic mirror 3, the first modulated light Lb2 is reflected by the dichroic mirror 3, and the second modulated lights Lr2, Lg2 are transmitted by the dichroic mirror 3 to be combined. It

Each modulated light Lb thus synthesized
2, Lg2, Lr2 are incident on the projection optical system 5 as a color projection light beam Lt. The projection optical system 5 forms an image of the incident color projection light beam Lt on a screen (not shown) to display an image.

Further, as shown in FIG. 13, the image display device according to the present invention is configured to include three or more dichroic mirrors and a reflective spatial light modulator corresponding to the dichroic mirrors as color separation / combination elements. It may be done.

That is, in this image display device,
The illumination light flux Ls emitted from the illumination optical system 1 is reflected by the mirror 2 and is incident on the first region of the first dichroic mirror 31, which is a flat plate-shaped first color separation / combination element. At this time, the first color component of the illumination light flux Ls is reflected by the first dichroic mirror 31, and as a light flux of the first color component, the first reflective spatial light modulator 41.
Incident on.

The other components of the illumination light flux Ls are
The light passes through the first dichroic mirror 31 and enters the first region of the second dichroic mirror 32 that is the second color separation / combination element. Here, the second color component of the incident light flux is reflected by the second dichroic mirror 32, and enters the second reflective spatial light modulator 42 as the light flux of the second color component.

The light fluxes of the other components of the incident light flux pass through the second dichroic mirror 32 and enter the first region of the third dichroic mirror 33 which is the third color separation / combination element. Here, the third color component of the incident light flux is reflected by the third dichroic mirror 33,
As the light flux of the color component of
It is incident on 3.

Each reflective spatial light modulator 41, 42, 43
In the above, when the light flux of each color component is incident on the polarization separation type diffractive optical element of each reflection type spatial light modulation element 41, 42, 43, it is a polarization component that maximizes the diffraction efficiency in each (P (or S)). The polarization component is diffracted and is incident on the polarization modulation elements (liquid crystal modulation layers) of the reflection-type spatial light modulation elements 41, 42, and 43 substantially vertically. The P (or S) polarization component incident on the polarization modulation element becomes an S (or P) polarization component according to the degree of modulation in the polarization modulation element, and is reflected by the reflection layer in this polarization modulation element. And re-enters the polarization splitting type diffractive optical element. Since the polarization separation type diffractive optical element mainly diffracts the P (or S) polarization component, the S (,
Alternatively, P) the polarization component is S by the polarization separation type diffractive optical element.
The polarized light splitting type diffractive optical element is transmitted except for the diffraction efficiency having the (or P) polarization component. The modulated light transmitted through the polarization splitting type diffractive optical element in this way enters the second regions of the corresponding dichroic mirrors 31, 32 and 33.

The third modulated light reflected by the third reflective spatial light modulator 43 is incident on the second region of the third dichroic mirror 33 and is reflected by the second region of the second dichroic mirror 32. It is incident on the region 2.

The second modulated light reflected by the second reflective spatial light modulator 42 and the third modulated light reflected by the third reflective spatial light modulator 43 are the second dichroic. The second modulated light is incident on the second region of the mirror 32, is reflected by the second dichroic mirror 32, and the third modulated light is transmitted through the second dichroic mirror 32 to be combined to produce the first modulated light. Is incident on the second region of the dichroic mirror 31.

The first modulated light reflected by the first reflective spatial light modulator 41 is combined in the second dichroic mirror 32 via the second and third reflective spatial light modulators 42 and 43. The luminous flux is incident on the second region of the first dichroic mirror 31, the first modulated light is reflected by the first dichroic mirror 31, and the luminous flux is transmitted through the first dichroic mirror 31 to be combined. To be done.

Each modulated light Lb thus synthesized
2, Lg2, Lr2 are incident on the projection optical system 5 as a color projection light beam Lt. The projection optical system 5 forms an image of the incident color projection light beam Lt on a screen (not shown) to display an image.

Here, further, the first to third dichroic mirrors 31 and 3 which are all color separation / synthesis elements.
A fourth reflective spatial light modulating element 44 may be provided as a final reflective spatial light modulating element on which the luminous flux of the color light component transmitted through each of the first areas 2 and 33 is incident. The modulated light reflected by the fourth reflective spatial light modulator 44 is transmitted through the second regions of all the dichroic mirrors 31, 32, 33, and the other reflective spatial light modulators 43, 42, 41.
Are sequentially combined with the modulated light reflected by.

The modulated lights thus synthesized are incident on the projection optical system 5 as a color projection light beam Lt.
The projection optical system 5 forms an image of the incident color projection light beam Lt on a screen (not shown) to display an image.

In this image display device, the number of color separation / synthesis elements may be four or more, and the number of reflective spatial light modulators may be five or more.

In each of the image display devices described above, the dichroic mirror, which is a color separation / combination element, receives the illumination light flux directed to the reflection type spatial light modulation element.
The color separation / synthesis characteristics may be different between the area 2 and the second area into which the modulated light flux reflected by the reflective spatial light modulator is incident. For example, in the first region and the second region, the characteristic for the P-polarized light flux in one region may be the characteristic for the S-polarized light flux in the other region. Further, the dichroic mirror may be formed such that the first region and the second region are separated.

Further, in the above image display device,
The reflective spatial light modulation element is not limited to the polarization modulation element and the polarization separation type diffractive optical element such as the hologram optical element as described above, and may be the polarization modulation element and the polarization absorption type optical element. . Further, the reflective spatial light modulator may be a movable mirror corresponding to a pixel (so-called “DMD”).

In the image display device described above, the image forming optical system is not limited to the above-mentioned projection optical system, and may be a virtual image optical system.

[0069]

As described above, in the image display device according to the present invention, one reflection type spatial light modulation on which one of the color light components separated in the first region of the color separation / combination element is incident. One modulated light reflected by the element, and another modulated light reflected by another reflective spatial light modulating element on which another color light component separated in the first region of the color separation / combination element is incident Is incident on the second region of the color separation / combination element, the one modulated light is reflected by the color separation / combination element, and the other modulated light is transmitted through the color separation / combination element to be combined, resulting in An image is displayed via the image optical system.

In this image display device, since the polarization beam splitter, which has been indispensable for the structure of the image display device using a plurality of reflection type spatial light modulators, is not used,
It is possible to provide a lightweight, small-sized, and inexpensive image display device.

Further, in this image display device, since a color separation / synthesis element such as a dichroic mirror is used as the color synthesis element, a bright image display having high light utilization efficiency without being influenced by the color dispersion of the diffractive optical element. It will be possible.

Further, in this image display device, when the reflection type spatial light modulation element is constituted by using the polarization separation type diffractive optical element, this polarization separation type diffractive optical element has a simple lattice-like refractive index distribution. Therefore, the production is easy, the maximum production is possible, and the alignment is easy when the reflective spatial light modulator is arranged on the front surface.

That is, according to the present invention, the size of the apparatus is reduced,
It is possible to provide an image display device that can be lightened, is easy to manufacture, has good light utilization efficiency, and can display a bright image.

[Brief description of drawings]

FIG. 1 is a plan view showing a configuration of an image display device according to the present invention.

FIG. 2 is a perspective view showing a manufacturing process of a polarization splitting type diffractive optical element which constitutes the image display device.

FIG. 3 is a perspective view showing the next manufacturing step of FIG. 2 for the polarization splitting type diffractive optical element.

FIG. 4 is a perspective view showing the next manufacturing process of FIG. 3 for the polarization splitting type diffractive optical element.

FIG. 5 is a perspective view showing an operation of the polarization splitting type diffractive optical element.

FIG. 6 is a graph showing the spectral diffraction efficiency of the first polarization splitting type diffractive optical element that constitutes the image display device.

FIG. 7 is a graph showing the spectral diffraction efficiency of the second polarization splitting type diffractive optical element that constitutes the image display device.

FIG. 8 is a graph showing the spectral diffraction efficiency of a third polarization separation type diffractive optical element that constitutes the above image display device.

FIG. 9 is a plan view showing an image display device according to the present invention, in which a polarizer and an analyzer are added.

FIG. 10 is a plan view showing an image display device according to the present invention, in which a prism including a color separation / combination element is added.

FIG. 11 is a plan view showing another embodiment (a configuration in which a color separation element and a color synthesis element are added) of the image display device according to the present invention.

FIG. 12 is a plan view showing another embodiment of the image display device according to the present invention (a configuration having two reflective spatial light modulators).

FIG. 13 is a plan view showing another embodiment of an image display device according to the present invention (a structure in which three or more color separation elements are used and four or more reflective spatial light modulation elements are used).

FIG. 14 is a plan view showing a configuration of a conventional image display device.

FIG. 15 is a plan view showing another example of the configuration of the conventional image display device.

[Explanation of symbols]

1 Illumination optical system, 3 Dichroic mirrors, 3b, 3
1 1st dichroic mirror, 3g, 32 2nd dichroic mirror, 33 3rd dichroic mirror, 4B, 41 1st reflection type spatial light modulator 4
G, 42 Second reflective spatial light modulator, 4R, 43
Third reflection type spatial light modulator, 44 Fourth reflection type spatial light modulator, 5 Projection optical system

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G02F 1/1335 505 G02F 1/1335 505 520 520 1/13357 1/13357 G03B 21/00 G03B 21/00 E 33/10 33/10 H04N 9/31 H04N 9/31 C F term (reference) 2H088 EA14 EA15 EA16 EA37 EA47 EA48 GA10 HA13 HA24 HA28 MA06 MA20 2H089 HA04 KA08 QA11 QA16 TA12 TA18 UA03 UA05 2H091 FA05X FA07X FA26X FA02 MA07 2H099 AA12 BA09 CA11 CA17 DA05 5C060 BC05 GA01 HC19 HC21 JA06

Claims (25)

[Claims] 1. A light source, a plate-shaped color separation / combination element into which a light beam from the light source is incident on a first region, and a light beam of a first color component reflected by the color separation / combination element is incident. A first reflection type spatial light modulation element, and a second reflection type spatial light modulation element on which the light flux of the second color component transmitted through the color separation / combination element is incident. First reflected by the spatial light modulator
And the second modulated light reflected by the second reflective spatial light modulator is the second one of the color separation / combination element.
The first modulated light is reflected by the color separating / combining element, and the second modulated light is transmitted by the color separating / combining element to be combined, and an image is displayed through the imaging optical system. An image display device characterized by performing. 2. The image display device according to claim 1, wherein the color separation / combination element has different color separation / composition characteristics in the first region and the second region. 3. The image display device according to claim 1, wherein the color separation / combination element is formed by separating the first region and the second region. 4. The image display device according to claim 1, wherein the first and second reflective spatial light modulators are composed of movable mirrors corresponding to pixels. 5. The image display device according to claim 1, wherein the first and second reflective spatial light modulators are composed of a polarization modulator and a polarization separation type diffractive optical element. 6. The image display device according to claim 5, wherein the polarization splitting type diffractive optical element is a hologram optical element. 7. The image display device according to claim 1, wherein the imaging optical system is a projection optical system. 8. The image display apparatus according to claim 1, wherein the image forming optical system is a virtual image optical system. 9. A light source, a flat plate-shaped first color separation / combination element into which a light beam from the light source is incident on a first region, and a first color reflected by the first color separation / combination element. A first reflection-type spatial light modulation element on which a component light beam is incident, and a flat plate-shaped second color separation / combination element on which the light beam transmitted through the first color separation / combination element is incident on a first region A second reflective spatial light modulator in which the light flux of the second color component reflected by the second color separation / combination element is incident, and a third color transmitted through the second color separation / combination element A third reflection type spatial light modulation element on which a component light flux is incident, and a second reflection type spatial light modulation element reflects the second reflection type spatial light modulation element.
And the third modulated light reflected by the third reflective spatial light modulator is incident on the second region of the second color separation / combination element to generate the second modulated light. The light is reflected by the second color separation / combination element, the third modulated light is transmitted by the second color separation / combination element to be combined, and is reflected by the first reflective spatial light modulation element. First
And the light flux synthesized by the second color separation / combination element via the second and third reflection type spatial light modulation elements is in the second area of the first color separation / combination element. Upon incidence, the first modulated light is reflected by the first color separation / combination element, the light flux is transmitted through the first color separation / combination element to be combined, and an image is displayed via an imaging optical system. An image display device characterized by performing. 10. The color separation / combination element includes a first region and a second region.
10. The image display device according to claim 9, wherein the color separation / synthesis characteristic is different from that of the area. 11. The color separation / combination element includes a first region and a second region.
The image display device according to claim 9, wherein the image display device and the image display device are formed separately. 12. The image display according to claim 9, wherein at least one of the first to third reflective spatial light modulators is composed of a movable mirror corresponding to a pixel. apparatus. 13. The image display device according to claim 9, wherein at least one of the first to third reflective spatial light modulators comprises a polarization modulator and a polarization separation type diffractive optical element. . 14. The image display device according to claim 13, wherein the polarization splitting type diffractive optical element is a hologram optical element. 15. The image display device according to claim 9, wherein the imaging optical system is a projection optical system. 16. The image display device according to claim 9, wherein the image forming optical system is a virtual image optical system. 17. A light source, and a plurality of flat plate-shaped color separation / combination elements, which are arranged in a layered manner with a gap therebetween and in which light fluxes from the light source are sequentially transmitted and made incident on a first region, respectively. A plurality of reflection-type spatial light modulators arranged corresponding to the respective color separation / combination elements and into which the luminous flux of the color light component reflected by the respective color separation / combination elements is incident, Each modulated light reflected by the element is incident on and reflected by the second region of the corresponding color separation / synthesis element, and the second region of the color separation / synthesis element closer to the light source than the corresponding color separation / synthesis element. The image display device is characterized in that the images are sequentially transmitted and sequentially combined, and an image is displayed through an imaging optical system. 18. A reflection type spatial light modulation element on which a luminous flux of a color light component transmitted through the first regions of all color separation / combination elements is incident, and the modulated light reflected by the reflection type spatial light modulation element is , Is transmitted through the second regions of all the color separation / combination elements, is combined with the modulated light reflected by another reflection-type spatial light modulation element, and displays an image through the imaging optical system. The image display device according to claim 17. 19. The color separation / combination element includes a first region and a second region.
18. The image display device according to claim 17, wherein the color separation / synthesis characteristic is different from that of the area. 20. The color separation / combination element includes a first region and a second region.
18. The image display device according to claim 17, wherein the image display device is formed separately from the area. 21. The image display device according to claim 17, wherein at least one of the plurality of reflective spatial light modulators is composed of a movable mirror corresponding to a pixel. 22. The image display device according to claim 17, wherein at least one of the plurality of reflective spatial light modulators comprises a polarization modulator and a polarization separation type diffractive optical element. 23. The image display device according to claim 22, wherein the polarization splitting type diffractive optical element is a hologram optical element. 24. The image display device according to claim 17, wherein the image forming optical system is a projection optical system. 25. The image display device according to claim 17, wherein the image forming optical system is a virtual image optical system.