JPH11282379A - Projection display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive projection display which can display a bright image through improvement as to the degradation of S/N ratio and which allows its optical system to be designed easily. SOLUTION: A quarter wavelength plate 18R is inserted between a reflection type space light modulation element 22R for red light and a dichroic prism 23 and a quarter wavelength plate 18G for green light is inserted between a reflection type space light modulation element 22G for green light and the dichroic prism 23. Also, a quarter wavelength plate 18B for blue light is inserted between a reflection type space light modulation element 22B for blue light and the dichroic prism 23 to display multi-color or full-color two-dimensional images.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a projection display for projecting and displaying a two-dimensional image such as a multi-color image or a full-color image on a screen.

[Summary of the Invention] The present invention relates to a reflection type spatial light modulator for green light in which a quarter-wave plate for red light is inserted between a reflection type spatial light modulator for red light and a dichroic prism. 1/4 for green light between dichroic prisms
A two-dimensional image such as a multi-color or full-color image is displayed by inserting a wave plate and inserting a quarter-wave plate for blue light between the reflective spatial light modulator for blue light and the dichroic prism.

[0003]

2. Description of the Related Art A conventional projection display 100 has a lamp 1 which emits visible light, as shown in a top view of FIG.
0, a light source unit 7 including an infrared light cut filter 12 that blocks infrared light, an ultraviolet light cut filter 13 that blocks ultraviolet light, and a lens 11 that converts visible light into parallel rays, and white light generated by the lamp 10. Light is red (R) light, green (G)
A white light distribution optical system 8 that separates the light into blue light and blue light (B) and distributes the light to a polarization beam splitter 9R for R light, a polarization beam splitter 9G for G light, and a polarization beam splitter 9B for B light. An R light polarization beam splitter 9R that sends the R light from the distribution optical system 8 to the R light reflection type spatial light modulator 22R as linearly polarized light of only the P component or the S component.
And the G light from the white light distribution optical system 8 is
The G light polarization beam splitter 9G sent to the G light reflection spatial light modulator 22G as linearly polarized light having only the component, and the B light from the white light distribution optical system 8 is converted into linearly polarized light having only the P or S component. Reflective spatial light modulator for B light 22
And a polarization beam splitter 9B for B light to be sent to B light.

As a spatial light modulating element, a reflection type spatial light modulating element for R light 22R for phase modulating R light in a linear polarization state of only the P component or S component sent from the polarizing beam splitter for R light 9R. And a G-light reflective spatial light modulator 22G for phase-modulating the G light in a linearly polarized state of only the P component or the S component sent from the G light polarization beam splitter 9G, and a B light polarization beam splitter 9B. And a reflection type spatial light modulator for B light 22B that phase-modulates the B light in a linearly polarized state of only the P component or the S component sent from the device.

Further, a reflection type spatial light modulator 22 for R light is used.
After providing the dichroic prism 23 that combines the RGB lights sent from the reflective spatial light modulator 22G for R and G light and the reflective spatial light modulator 22B for B light and sends them to the projection lens 24 as one beam. It is configured.

FIG. 12 schematically shows the structure of the dichroic prism. In the figure, ABCD and A '
B′C′D ′ represents the upper and lower surfaces of the dichroic prism. On the AA'C'C plane, a dielectric multilayer mirror that reflects B light and transmits other visible light is formed. Also,
On the BB′D′D surface, a dielectric multilayer mirror that reflects R light and transmits other visible light is formed.

[0007] The projection lens 24 is formed of RGB spatial light modulating elements 22R, 22G and 22B for RGB light.
An optical image is formed on the screen 2. White light distribution optical system 8
Is a mirror 14 that reflects white light and a mirror that transmits R light and G
It comprises a dielectric multilayer mirror 15 that reflects B light, a dielectric multilayer mirror 16 that reflects G light and transmits B light, and a mirror 17 that reflects R light.

This conventional projection display has the following features. (1) Since the reflection type spatial light modulator is used, most of the incident light can be modulated and a bright image can be displayed. ) Since the dichroic prism is used, the distance between the reflective spatial light modulator and the projection lens can be reduced, and a large area image can be displayed even when the distance between the display and the screen is short. In addition, since the distance between the reflective spatial light modulator and the projection lens is short, it has excellent characteristics such that the device can be compactly assembled.

[0009]

However, in the above-mentioned conventional projection type display 10, the use of a dichroic prism has the following problems.

<Problems of dichroic prism> FIG.
2 (a) and (b) are views showing an overview of a dichroic prism, and are four right-angled triangular prisms of the same shape made of a transparent material.
(FIG. 12A: ∠AEB and ∠A'E'B 'are right angles). As described above, the dielectric multilayer mirror that reflects the R light and transmits the other light is formed on the BB′D′D plane in FIG. 12B. A dielectric multilayer mirror that reflects B light and transmits other light is provided on the AA'C'C surface.

These dielectric multilayer mirrors cannot completely reflect the R light or the B light.
As shown in (1), the transmittance shows different reflectance depending on the wavelength. As shown by the reflection characteristics of the dielectric multilayer mirror for blue light in FIG.
When the reflectance is increased (up to 480 nm), a reflectance of several percent remains even in a region where the reflectance is desired to be zero (a region having a wavelength longer than 500 nm), and noise light is formed. Further, as shown by the reflection characteristics of the dielectric multilayer mirror for red light in FIG.
If the noise light is reduced, the required area (600
７００700 nm). In any case, a large amount of light is transmitted without being reflected in a wavelength region corresponding to a boundary of RGB light.

FIG. 11 shows that the dichroic prism 23 and the polarizing beam splitter 9 for R light, G light and B light are used.
R, 9G, 9B, red light, green light, and blue light reflective spatial light modulators 22R, 22G, 22B are extracted from FIG. The problem of the dichroic prism resulting from the reflection characteristics of the mirror will be clarified. In FIG. 14, only the optical path of the B light is illustrated, but the G light and the R light are also the same as the B light, and the reflective spatial light modulators for red light, green light, and blue light 22R, 22G, and 22B. There is a ray passing through. Here, in order to avoid complicating the description of the drawings, only a part of the optical path of the B light is illustrated. 14 in FIG.
00 to 710 are passing points of the B light. In FIG. 14, for explanation, the passing points 610, 680, 690 are markedly spaced apart, the passing points 630, 640, 710, 720 are markedly spaced apart, the passing points 650 and 660 are markedly spaced apart, and further passed Although the points 620, 670, and 700 are shown far apart, they are not really far apart. If the B light is perpendicularly incident on the input / output surface of FIG. 14 and the B light is a perfect parallel ray, the passing points 610 and 68
0 and 690 are at the same position and passing points 630 and 64
0, 710, and 720 are at the same position, pass points 650 and 660 are at the same position, and pass points 620, 670, and 7
00 should also be in the same position.

Here, the signal-to-noise ratio (S / N) of the projected light is determined under the following conditions. (1) The normalized intensity of incident light (light passing through the passing point 600 in the case of B light) is set to 1. (2) The reflectance of the dielectric multilayer mirror on the AA'C'C plane for B light is 1-Ab, and the transmittance is Ab. (3) The reflectance of the dielectric multilayer mirror on the AA'C'C plane for the R light is 0, and the transmittance is 1 (corresponding to 100%). (4) The transmittance of the dielectric multilayer mirror on the AA'C'C plane for the short wavelength component of G light (50% of the total G light power) is 1-Ag, and the reflectance is Ag. The remaining long wavelength components are all BB'D'D
Transmit through the surface. (5) The reflectance of the dielectric multilayer mirror on the BB'D'D plane for R light is 1-Ar, and the transmittance is Ar. (6) The reflectance of the dielectric multilayer mirror on the BB'D'D surface with respect to the B light is 0 and the transmittance is 1. (7) The transmittance of the dielectric multilayer mirror on the BB'D'D plane for the long wavelength component of G light (50% of the total G light power) is 1-Ag, and the reflectance is Ag. The remaining short wavelength components are all BB'D'D
Transmit through the surface. (8) A noise component that reflects the AA'C'C plane and the BB'D'D plane four or more times is very small and is ignored. (9) When linearly polarized light having only the S component propagates through the optical path R1 and enters the red light reflective spatial light modulator 22R, the linearly polarized light is modulated by the red light reflective spatial light modulator 22R.
Linearly polarized light having only the P component that travels straight through the R light polarizing beam splitter 9R and propagates along the optical path R2 (referred to as signal light)
When the linearly polarized light having only the P component propagates along the optical path R2 and enters the reflection type spatial light modulation element for red light 22R, the polarization beam splitter 9R for R light is defined as Tr.
And the normalized intensity of the linearly polarized light (noise light) having only the P component propagating straight through the optical path R2 is 1-Tr. (10) When linearly polarized light having only the S component propagates through the optical path B1 and enters the blue light reflective spatial light modulator 22B, the blue polarized light is modulated by the blue light reflective spatial light modulator 22B.
Linearly polarized light having only a P component that travels straight through the B light polarization beam splitter 9B and propagates along the optical path B2 (referred to as signal light)
Is defined as Tb, and a polarization beam splitter 9B for B light when linearly polarized light having only the P component propagates through the optical path B2 and enters the reflection type spatial light modulation element 22B for blue light.
And the normalized intensity of linearly polarized light (noise light) having only the P component propagating straight through the optical path B2 is 1-Tb. (11) When linearly polarized light having only the S component propagates through the optical path G1 and enters the green light reflective spatial light modulator 22G, the linearly polarized light is modulated by the green light reflective spatial light modulator 22G.
A linearly polarized light having only a P component that travels straight through the G light polarizing beam splitter 9G and propagates along the optical path G2 (referred to as signal light).
The polarization intensity of the G light polarization beam splitter 9G when linearly polarized light having only the P component propagates through the optical path G2 and enters the reflection type spatial light modulation element for green light 22G is defined as Tg.
And the normalized intensity of the linearly polarized light (noise light) having only the P component propagating straight through the optical path G2 is 1-Tg. (12) The polarization beam splitters for R light, G light, and B light have ideal characteristics of completely transmitting the P component and completely reflecting the S component. (13) Absorption, scattering, reflection, etc. of the optical elements constituting FIG. 14 are ignored. Taking the B light shown in FIG. 14 as an example, the signal light intensity and the noise light intensity are estimated. B at passing point 610
Since the light intensity is Tb, the signal light intensity Psb at the passing point 620
Is given by Psb = (1-Ab) Tb... (1) On the other hand, the intensity of B light that becomes noise passing through the dielectric multilayer mirror on the AA'C'C plane becomes AbTb at the passing point 630. Since this light is incident on the red light reflective spatial light modulator 22R and modulated, the intensity at the passing point 640 is AbTb
(1-Tr). Part of this noise light is reflected by the dielectric multilayer mirror on the AA'C'C plane, and the intensity at the passing point 650 is Ab ² T
b (1-Tr). Since this light is modulated by the reflection type spatial light modulator for green light 22G, the intensity at the passing point 660 is
Ab ² Tb (1-Tr) (1-Tg). This noise light enters the dielectric multilayer mirror on the AA'C'C plane again, passes through it, and reaches the final passing point 670. At this time, the noise intensity of the B light is Ab ² (1-A
b) Tb (1-Tr) (1-Tg). The B light that has passed through the passing point 640 passes through the dielectric multilayer mirror on the AA'C'C plane, passes through the passing points 680, 690, and 700 and has another noise light (the intensity of which is Ab ² ( 1-Ab) Tb (1-Tr) (1-Tb)). The noise light is not only this, but the passing point 71 in FIG.
0, 720, the reflective spatial light modulator for red light 22R and the reflective spatial light modulator for blue light 2R
2B, the reflection type spatial light modulator 22G for green light, the dichroic prism 23, etc., pass through and reflect, and repeat multiple reflections. Here, in the noise light, only the term on which Ab ² which is a light ray with high intensity is
When the intensity is calculated, the total sum Pnb estimated for the inner ring of the noise intensity of the B light is

(Equation 1) Given by

By the same calculation, the signal intensity Psr of the R light is given by Psr = (1-Ar) Tr (3) The noise intensity Pnr estimated for the inner ring of the R light is

(Equation 2) Given by

Further, when the signal intensity Psg of the G light is determined in consideration of the conditions (4) and (7), the following expression is obtained: Psg = (1-Ag) Tg (5) Further, when the noise intensity Png estimated for the inner ring is obtained while considering the conditions of (4) and (7),

(Equation 3) Becomes

From the equations (1) to (6), the signal-to-noise ratio S / N
Is

(Equation 4) Given by

FIG. 15 shows an example in which the relationship between S / N and Ar is obtained by using equation (7) under the condition that Ag = Ab = 0.1 and Tg = Tb = 0.1 for simplicity. This shows that the modulation of the reflective spatial light modulator and the crosstalk characteristics of the dichroic prism greatly affect the signal-to-noise ratio. For example,
When Tr = 0.6, the signal-to-noise ratio is 100: 1 for Ar> 0.08
It becomes below. Also, when Tr = 0.1, the signal-to-noise ratio is only about 33: 1 at the maximum irrespective of the value of Ar.

In order to avoid the above problem, the reflectance of the dichroic prism is improved, and light having a wavelength with a low reflectance of the dichroic prism 23 is supplied to the dichroic prism 23 before the light enters the white light distribution optical system 8. In the optical path from the white light distribution optical system 8 to the dichroic prism 23, the wavelengths of the three primary colors must be limited. Although this method can reduce noise light,
At the same time, the signal light is reduced, which results in an undesirable result that the projected image becomes dark.

The present invention has been made in view of the above circumstances, and has as its object to provide an inexpensive projection display that can display a bright image by improving the deterioration of the SN ratio, and that can easily design an optical system.

[0020]

To achieve the above object, according to the present invention, there is provided a light source for generating white light, and the white light is converted into three primary color lights of red light, green light and blue light. A white light distribution optical system including a dichroic mirror that has the function of decomposing and distributing to separate optical paths, and a red light that separates red light into linearly polarized light having only a P component and linearly polarized light having only an S component that are orthogonal to each other. Polarization beam splitter for
A polarizing beam splitter for green light that separates green light into linearly polarized light having only a P component and a linearly polarized light having only an S component, and a linearly polarized light having blue light and only a P component that is orthogonal to each other. A polarization beam splitter for blue light that separates into linearly polarized light having only a component, and a reflection for red light that converts linearly polarized light having only a red P component or linearly polarized light having only an S component into light of an arbitrary polarization state -Type spatial light modulator, a green-light reflective spatial light modulator that converts linearly polarized light having only a green P component or linearly polarized light having only an S component into light of an arbitrary polarization state, and a blue P component A blue-light reflective spatial light modulator that converts a linearly polarized light having only S or a linearly polarized light having only an S component into light of an arbitrary polarization state, and a red linearly polarized light emitted from a polarization beam splitter for red light. For red light 1 to be converted into red elliptically polarized light having a polarization state close light into circularly polarized light or circularly polarized light
A 波長 wavelength plate and a green light 1 for converting green linearly polarized light emitted from a green light polarizing beam splitter into circularly polarized light or green elliptically polarized light having a polarization state close to circularly polarized light.
A 波長 wavelength plate and a green light 1 for converting blue linearly polarized light emitted from a blue light polarized beam splitter into circularly polarized light or blue elliptically polarized light having a polarization state close to circularly polarized light.
A quarter wavelength plate, a dichroic prism having a function of combining three primary color lights entering from different optical paths and emitting the light from one optical path, and a projection lens for projecting the combined light. I do.

According to a second aspect of the present invention, in the projection display according to the first aspect, the reflective spatial light modulating element for red light is driven by a red light image electric signal, and the reflective spatial light modulating element for green light is used. The element is driven by an image electric signal for green light, and the reflective spatial light modulator for blue light is driven by an image electric signal for blue light, and the red modulated spatial light modulating element is modulated by the reflective spatial light modulator for red light. The light is guided again to the polarization beam splitter for red light, linearly polarized light having only the red S component or P component is selected and guided to the 赤色 wavelength plate for red light, and the reflective spatial light for green light is selected. The green light modulated by the modulation element is led to the green light polarizing beam splitter again,
The linearly polarized light having only the green S component or the P component is selected, guided to the green light quarter-wave plate, and the blue light modulated by the blue light reflective spatial light modulator is again converted into the blue light. Linearly polarized light having only the blue S component or P component is selected, guided to the blue light quarter-wave plate, and transmitted through the red quarter-wave plate to form a circularly polarized light. Wave light or red elliptically polarized light having a polarization state close to circularly polarized light is guided to the dichroic mirror, and transmitted through the 波長 wavelength plate for green light, and green elliptically polarized light having a polarization state close to circularly polarized light or circularly polarized light. Guides the wave light to the dichroic mirror, transmits the blue quarter-wave plate, and guides the circularly polarized light or blue elliptically polarized light having a polarization state close to circularly polarized light to the dichroic mirror,
The three primary color lights are combined by the dichroic prism and guided to a screen via the projection lens to display a full-color or multi-color image.

According to a third aspect of the present invention, in the projection type display according to the first or second aspect, each of the reflective spatial light modulators comprises a transparent substrate on which a transparent electrode is laminated, and a liquid crystal molecule having a small or zero applied voltage. The negative dielectric anisotropy, in which the direction parallel to the long axis of the liquid crystal molecules is aligned perpendicular to the surface of the transparent substrate when the liquid crystal molecules are in the off state, or arranged so as to be displaced within several degrees from the vertical. A light modulation layer having a nematic liquid crystal, a two-dimensional array electrode in contact with the light modulation layer, and a voltage applied to the two-dimensional array electrode to control the arrangement of the nematic liquid crystal for each pixel. And a substrate having an array of electronic circuits.

According to a fourth aspect of the present invention, in the projection display according to the first or second aspect, each of the reflective spatial light modulators includes a transparent substrate on which a transparent electrode is laminated, and an off-state in which an applied voltage is small or zero. When arranged parallel to the surface of the transparent substrate, and the direction parallel to the long axis of the nematic liquid crystal molecules closest to the transparent substrate and the direction parallel to the long axis of the nematic liquid crystal molecules farthest to the transparent substrate are 45 degrees. A light modulating layer provided with a 45-degree twisted nematic liquid crystal having a positive dielectric anisotropy arranged at an angle, a two-dimensional array electrode in contact with the light modulating layer, and a two-dimensional array electrode And a substrate having an electronic circuit arranged in a matrix for controlling the arrangement of the nematic liquid crystal twisted by 45 degrees for each pixel by applying a voltage.

According to a fifth aspect of the present invention, in the projection display according to the first or second aspect, the quarter-wave plate for red light, green light and blue light is a uniaxial single crystal or one-quarter wavelength plate.
It is an axial organic compound.

According to a sixth aspect of the present invention, in the projection type display according to the first, second or fifth aspect, the 1/4 for the red light is provided.
A wavelength plate is brought into close contact with the red light polarizing beam splitter or the dichroic prism, and the green light
A quarter-wave plate is closely attached to the green light polarization beam splitter or dichroic prism, and the blue light quarter-wave plate is closely adhered to the blue light polarization beam splitter or dichroic prism.

In the above configuration, in the projection type display of the first and second aspects, the white light generated from the light source is decomposed into three primary color lights by the white light distribution optical system including a dichroic mirror, and the red light is converted to the red light. Leading to a polarizing beam splitter for light, guiding green light to the polarizing beam splitter for green light, guiding blue light to the polarizing beam splitter for blue light, and polarizing beam splitter for red, green and blue light The three primary color lights are decomposed into linearly polarized light having only a P component and linearly polarized light having only an S component, and the linearly polarized light having only a red P component or an S component is converted into the reflective spatial light for red light. The linearly polarized light having only the green P component or the S component is guided to the reflective spatial light modulator for green light, and only the blue P component or the S component is guided to the modulation device. One linearly polarized wave light guided to the reflection type spatial light modulator for the blue light, the image electric signal for red light,
Driving the red-light reflective spatial light modulator, driving the green-light reflective spatial light modulator by a green light image electric signal, and driving the blue light reflective electric light by a blue-light image electric signal. The spatial light modulator is driven, and the red light modulated by the reflective red light spatial light modulator is guided again to the red light polarizing beam splitter, and the red S component or P
The linearly polarized light having only the component is selected and the 1 /
The green light modulated by the reflection type spatial light modulator for green light is guided to the four-wavelength plate again, and guided to the polarization beam splitter for green light again, and linearly polarized light having only green S component or P component is selected. To the green light quarter-wave plate,
The blue light modulated by the reflection type spatial light modulator for blue light is guided again to the polarization beam splitter for blue light, and linearly polarized light having only the blue S component or P component is selected and the blue light 1 Led to a 波長 wavelength plate and 前 記
A red elliptically polarized light having a polarization state close to circularly polarized light or circularly polarized light transmitted through the wave plate is guided to the dichroic prism, and is transmitted through the green quarter wave plate to be substantially circularly polarized light or circularly polarized light. The green elliptically polarized light having a polarization state is guided to the dichroic prism,
A circularly polarized light or a blue elliptically polarized light having a polarization state close to a circularly polarized light that has passed through a four-wavelength plate is guided to the dichroic prism, and the three primary colors are combined by the dichroic prism, and the screen is passed through the projection lens. Leads to
Display full-color or multi-color images.

By this series of operations, the problem of the conventional projection display can be solved, the deterioration of the SN ratio can be improved and a bright image can be displayed, and the design of the optical system is easy and an inexpensive device can be provided. provide.

According to a third aspect of the present invention, there is provided the projection type display according to the first and second aspects, wherein the transparent substrate provided with the transparent electrode and the off state in which the applied voltage is small or zero and the liquid crystal molecules do not move. In this case, a nematic liquid crystal having a negative dielectric anisotropy is arranged such that the direction parallel to the major axis of the liquid crystal molecules is perpendicular to the surface of the transparent substrate, or is aligned within a few degrees from the perpendicular. When,
A reflective space for red light having at least a two-dimensional array electrode and a substrate having an electronic circuit arranged in a matrix for applying a voltage to the two-dimensional array electrode and controlling the arrangement of the nematic liquid crystal for each pixel. The light modulating element, the reflective spatial light modulating element for green light, and the reflective spatial light modulating element for blue light are driven by an electric signal, and are arranged vertically with respect to the surface of the transparent substrate, or a number from the vertical. The arrangement of the nematic liquid crystal having negative dielectric anisotropy arranged so as to be shifted within a degree is changed to change the polarization state of the linearly polarized light incident on the reflection type spatial light modulator.

By this series of operations, the problems of the conventional projection display can be solved, the deterioration of the SN ratio can be improved and a bright image can be displayed, and the optical system can be easily designed and the cost can be reduced. provide.

According to a fourth aspect of the present invention, there is provided the projection type display according to the first and second aspects, wherein the transparent substrate attached to the transparent electrode and the transparent substrate when the applied voltage is in a small or zero off state. And the direction parallel to the long axis of the nematic liquid crystal molecules closest to the transparent substrate and the direction parallel to the long axis of the nematic liquid crystal molecules farthest away from the transparent substrate form an angle of 45 degrees. A 45-degree twisted nematic liquid crystal having a positive dielectric anisotropy, a two-dimensional array electrode, and a voltage is applied to the two-dimensional array electrode so that the arrangement of the 45-degree twisted nematic liquid crystal is changed for each pixel. A reflective spatial light modulator for red light, a reflective spatial light modulator for green light, and a reflective sky for blue light having at least a substrate having electronic circuits arranged in a matrix to be controlled. And driving the light modulation element in an electrical signal, to change the sequence of the 45-degree nematic liquid crystal changes the polarization state of the linearly polarized light incident on the reflective spatial light modulator.

By this series of operations, the problems of the conventional projection type display can be solved, the deterioration of the SN ratio can be improved and a bright image can be displayed, and the optical system can be designed easily and at low cost. provide.

According to a fifth aspect of the present invention, there is provided the projection type display according to the first and second aspects, wherein the uniaxial single crystal or uniaxial organic compound is used for red light, green light and blue light. 1/4 wavelength plate for
An image is displayed by converting the linearly polarized light into circularly polarized light or elliptically polarized light close to circularly polarized light.

This series of operations solves the problems of the conventional projection type display, improves the SN ratio, displays a bright image, and makes it easy to design an optical system at low cost. provide.

According to a sixth aspect of the present invention, in the projection type display according to the first, second and fifth aspects, the 光 wavelength plate for red light is replaced by the polarizing beam splitter or dichroic prism for red light. The green light quarter-wave plate is closely attached to the green light polarizing beam splitter or dichroic prism, and the blue light quarter-wave plate is aligned to the blue light polarizing beam splitter or dichroic prism. The close contact reduces the reflection of the 波長 wavelength plate for red light, green light and blue light. Also, 1
By attaching a quarter-wave plate of an axial organic compound to a polarizing beam splitter or a dichroic prism, linearly polarized light can be circularly polarized light or elliptically polarized light close to circularly polarized light while minimizing weight and space. And display the image.

By this series of operations, the problems of the conventional projection type display can be solved, the deterioration of the S / N ratio can be improved, and a bright image can be displayed. provide.

[0036]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS << Configuration of Projection Display >> FIG. 1 is a configuration diagram of a projection display according to the present invention.
The projection display 1 shown in FIG. 1 displays red (R), green (G), and blue (B) images, which are circularly polarized light or elliptically polarized light having a polarization state close to circularly polarized light, on a screen 2. Show the observer a full-color or multi-color image.

The projection display 1 has a lamp 10 for emitting visible light, an infrared light cut filter 12 for blocking infrared light, an ultraviolet light cut filter 13 for blocking ultraviolet light, and a light emitted from the lamp 10 in parallel. White light that separates the RGB light from the light source unit 7 having the lens 11 that converts the light into light, and distributes the separated RGB light to the R light polarization beam splitter 9R, the G light polarization beam splitter 9G, and the B light polarization beam splitter 9B. And a distribution optical system 8.

As a spatial light modulator, a reflective spatial light modulator for red light 22R for modulating linearly polarized light having only a P component or only an S component separated by a polarization beam splitter 9R for R light, and G A reflective spatial light modulator for green light 2 that modulates linearly polarized light having only the P component or only the S component separated by the polarization beam splitter 9G for light.
2G and a blue light reflective spatial light modulator 22B that modulates linearly polarized light having only the P component or only the S component separated by the B light polarization beam splitter 9G.

As a quarter-wave plate, the red linearly polarized light modulated by the red light reflective spatial light modulator 22R and passed again through the R light polarizing beam splitter 9R is converted into a circularly polarized light or a circularly polarized light. The light is modulated by the R-light quarter-wave plate 18R, which converts the light into an elliptically polarized light having a polarization state close to the polarization, and the reflection-type spatial light modulator 22G for green light, and G passes again through the light polarization beam splitter 9G. Green linearly polarized light is modulated by a quarter-wave plate 18G for G light that converts circularly polarized light or elliptically polarized light having a polarization state close to circularly polarized light, and a reflective spatial light modulator for blue light 22B, And a B-light quarter-wave plate 18B that converts the blue linearly polarized light that has passed through the B-light polarizing beam splitter 9B again into circularly polarized light or elliptically polarized light having a polarization state close to circularly polarized light. I have.

Further, R light that has passed through the R light quarter-wave plate 18R, G light that has passed through the G light quarter-wave plate 18G, and B light that has passed through the B light quarter-wave plate 18B. Dichroic prism 23 that combines light and sends it to projection lens 24
And a projection lens 24 for enlarging and projecting the modulated light from the dichroic prism 23 onto the screen 2.

In the above configuration, in the projection display 1, the RGB distributed from the white light distribution optical system 8 are used.
Converts light into RGB light polarizing beam splitters 9R, 9G, 9B
And RGB light with linearly polarized light having only a P component and S
Is divided into linearly polarized light having only components, and the red, green, and blue reflective spatial light modulators 22R, 22G, and 22B driven by RGB image electrical signals use only the P component or the S component of the RGB light. Modulation is performed to change the polarization state of linearly polarized light having only components. These RGB lights are again converted into the RGB light polarizing beam splitters 9R, 9G, 9B.
And extracted as intensity-modulated RGB light in a linearly polarized state having only an S component or only a P component. These linearly polarized RGB intensity modulated lights are used for R light, G light,
The quarter-wave plates 18R, 18G, and 18B for B light convert the light into circularly polarized light or elliptically polarized light having a polarization state close to circularly polarized light, combine these RGB lights with the dichroic prism 23, and project the projection lens 24. To display a full-color or multi-color image on the screen 2.

The white light distribution optical system 8 includes a mirror 14 for reflecting the RGB light from which the infrared light and the ultraviolet light contained in the parallel light have been cut by the infrared light cut filter 12 and the ultraviolet light cut filter 13. And transmit R light,
A dichroic mirror 15 that reflects GB light, a dichroic mirror 16 that reflects G light, and transmits B light,
A mirror 17 that reflects the R light, and reflects the RGB light that has passed through the ultraviolet light cut filter with the mirror 14;
The dichroic mirrors 15 and 16 distribute the RGB light to the R light polarizing beam splitter 9R, the G light polarizing beam splitter 9G, and the B light polarizing beam splitter 9B, respectively.

The polarization beam splitter 9R for R light is desirably coated with an anti-reflection film on each input / output surface, and includes only the P component or only the S component contained in the R light emitted from the white light distribution optical system 8. Is selected and guided to the reflective spatial light modulator for red light 22R. Further, the R light polarization beam splitter 9R selects linearly polarized light having only the S component or only the P component from the light emitted from the red light reflective spatial light modulator 22R, and guides the linearly polarized light to the dichroic prism 23.

The polarization beam splitter 9G for G light preferably has an antireflection film coated on each input / output surface, and has only P component or only S component contained in the G light emitted from the white light distribution optical system 8. Is selected and guided to the reflection type spatial light modulator for green light 22G. Further, the polarization beam splitter 9G for G light selects linearly polarized light having only the S component or only the P component from the light emitted from the reflective spatial light modulator for green light 22G, and guides the light to the dichroic prism 23.

The polarization beam splitter 9B for B light is preferably coated with an anti-reflection film on each input / output surface, and includes only the P component or the S component contained in the B light emitted from the white light distribution optical system 8. Is selected and guided to the blue light reflective spatial light modulator 22B. Further, the polarization beam splitter 9B for B light selects linearly polarized light having only the S component or only the P component from the light emitted from the reflection type spatial light modulation element 22B for blue light, and guides the light to the dichroic prism 23.

The R-light quarter-wave plate 18R converts the linearly polarized light selected by the R-light polarizing beam splitter 9R into circularly polarized light or elliptically polarized light having a polarization state close to circularly polarized light. The light is sent to the dichroic prism 23.

The G light quarter-wave plate 18G converts the linearly polarized light selected by the G light polarizing beam splitter 9G into circularly polarized light or elliptically polarized light having a polarization state close to circularly polarized light. The light is sent to the dichroic prism 23.

The B light quarter-wave plate 18B converts the linearly polarized light selected by the B light polarizing beam splitter 9B into circularly polarized light or elliptically polarized light having a polarization state close to circularly polarized light. The light is sent to the dichroic prism 23.

1/4 wavelength plates 18R, 18G for RGB light,
18B is made of a uniaxial single crystal such as quartz or a uniaxial organic compound such as a stretched plastic, and these are adhered to the polarization beam splitters 9R, 9G, 9B for RGB light or adhered to a dichroic prism. It is also possible to convert linearly polarized light into circularly polarized light or elliptically polarized light having a polarization state close to circularly polarized light while suppressing the influence of reflection. In particular, RGB consisting of a uniaxial organic compound
Since the quarter-wave plates for light 18R, 18G, and 18B are lightweight, inexpensive, and thin, the above functions can be achieved with little burden on the weight, size, and cost of the display.

The dichroic prism 23 is arranged as shown in FIG.
4 of the same shape made of the same transparent material as shown in (a)
A dielectric having a cube or rectangular parallelepiped shape as shown in FIG. 12 (b), in which R light is reflected on the BB'D'D surface, and other visible light is transmitted. It has a multilayer mirror, a dielectric multilayer mirror that reflects B light on the AA'C'C plane and transmits other visible light, and converts R light incident on the dichroic prism 23 into BB'D'D. Reflected on the surface,
The B light incident on the dichroic prism 23 is reflected by the AA'C'C plane, and the G light incident on the dichroic prism 23 is transmitted. The dichroic prism 23 sends the RGB light selected by the polarization beam splitter 9R for R light, the polarization beam splitter 9G for G light, and the polarization beam splitter 9B for B light to the projection lens 24 as one beam.

The reflective spatial light modulators 22R, 22G, and 22B for red light, green light, and blue light take in the RGB image electric signals IR, IG, and IB, and are used as reflective spatial light modulators. Controls the alignment of the nematic liquid crystal as a component.

<< Configuration of Reflective Spatial Light Modulator >> Next, referring to a schematic diagram showing a cross section of the reflective spatial light modulator of FIG. 2, the reflective spatial light modulator 22R used in the above embodiment will be described. , 22G and 22B will be described in detail.

The reflective spatial light modulator 22-1 shown in FIG.
A substrate 25 made of silicon or glass, a two-dimensional array electrode 26 formed on the substrate 25,
A plate-shaped transparent electrode 27, a light modulation layer 28 inserted between the electrodes 26, 27, a first antireflection film 29 in contact with the plate-shaped transparent electrode 27, and a transparent substrate in contact with the antireflection film 29 30 and a second antireflection film 31 in contact with the transparent substrate 30. Here, the antireflection films 29 and 31 can be omitted. Further, the two-dimensional array electrode 26 is provided with switches 32 corresponding to the number of pixels,
Each electrode has an image electric signal supply line 33 and a scanning signal supply line 3
4 and a switch 32 are connected. That is, only the switch 32 to which the image electric signal and the scanning signal are simultaneously supplied is turned on, and the image electric signal is supplied only to the electrode of the two-dimensional array electrode 26 connected to the switch 32 in the ON state. Has become.

The two-dimensional array electrode 26 is composed of minute pixel electrodes corresponding to the pixels, and each pixel electrode has at least one pixel electrode.
It has a structure with a number of switches 32. here,
Assuming that the number of pixels is L, the number of image electrical signal supply lines 33 is M, and the number of scanning signal supply lines 34 is N, the relationship is L = M × N. In order to prevent the linearly polarized light 35 from directly entering the switch 32, as shown in FIG.
Reference numeral 2 is provided below the two-dimensional array electrode 26. The pixel electrode corresponding to the pixel is flattened so that light can be reflected regularly, and is made of metal or a metal and a dielectric multilayer mirror formed on the metal. Hereinafter, unless otherwise specified, it is assumed that the pixel electrode corresponding to the pixel is made of a flat metal that reflects most of the light incident on the electrode.

The switch 32 has a function of receiving the scanning signal supplied from the scanning signal supply line 34 and transmitting the image electric signal supplied from the image electric signal supply line 33 to the two-dimensional array electrode 26. Is not supplied, it is necessary to have a high blocking resistivity so that the charges sent to the two-dimensional array electrode 26 are not released at least until the next scanning signal is supplied.

As the switch 32, a MOS (Metal Ox
A transistor, a thin film transistor (TFT: Thin Film Transistor), a diode, and the like are used. Typical switches using diodes include ring diode connections (eg, S. Togas
hi: SID Digest, pp.324-325 (1984)), reverse facing diode connection (eg, N. Szydlo: Japan Display ´83 D
igest, pp. 416-418 (1985)) and MIM (Metal In
sulator Metal) element (for example, S. Morozumi: Japan D
isplay '83 Digest, pp. 404-407 (1983)).

<< Reflective Spatial Light Modulator 22-2 Using MOS Transistor Array >> FIG. 4 shows a partial cross section of a reflective spatial light modulator 22-2 using a MOS transistor array as a switch 32. .

As shown in FIG. 4, the MOS transistor 40 constituting the switch 32 is formed on a silicon substrate 25a. 41 is a source electrode line, 42 is a drain electrode line, 43 is a gate electrode line, and the insulating layers 44 and 4
5 is formed. The reflection type spatial light modulator 22-2 includes a capacitor 46 for accumulating electric charges, a light shielding layer 47 formed on the insulating layer 45 to block the linearly polarized light 35, and an insulating layer 48 on the light shielding layer 47. The electrode 26, which receives an electric charge from the drain electrode line 42 to supply an electric field to the light modulation layer 28, the transparent electrode 27 common to all pixels, a transparent substrate 30, and a first anti-reflection film. 29 and a second antireflection film 31.
Of course, the first antireflection film 29 and the second antireflection film 3
It is possible to omit 1. The electrode 26 has a size corresponding to one pixel as described above, and the source electrode line 41
And each pixel electrode is independently driven in accordance with the amount of electric charge supplied to the gate electrode line 42. Further, the transparent electrode 27
It is a common electrode and has a role of supplying the same potential to all pixels.

As shown by a broken line in FIG.
It is also possible to form a dielectric multilayer mirror 49 between the optical modulator 28 and the light modulation layer 28, and to use the modulated linearly polarized light 35 more efficiently.

<< Reflective Spatial Light Modulator 22-3 Using TFT Array >> FIG. 5 shows a partial cross section of a reflective spatial light modulator 22-3 using a TFT array as a switch 32.

In FIG. 5, 25b is a glass substrate, 50b
Is a gate electrode, 51 is an insulating layer made of SiNx, 52 is a channel layer of amorphous silicon (a-Si), 53 is a SiNx insulating layer for protecting the channel layer 52, 54 is a source electrode, and 55 is n + a. -Si film, 56 is an insulating layer made of SiNx, 57 is a drain electrode, 26 is an electrode connected to the drain electrode 57 to apply an electric field to the light modulation layer 28, 27 is a transparent electrode common to all pixels, 29 is A first antireflection film, 30 is a transparent substrate, 31 is a second antireflection film, and 35 is linearly polarized light. Also in this case, the first anti-reflection film 29 and the second anti-reflection film 31 can be omitted.

In the structure of the reflective spatial light modulator 22-3 using the TFT array as the switch 32 shown in FIG.
Although there is no light shielding layer corresponding to the light shielding layer 47 in FIG. 4, a light shielding layer 58 can be provided as shown in FIG. Also, as shown by broken lines in FIGS. 4 and 5, a dielectric multilayer mirror 49 may be formed between the electrode 26 and the light modulation layer 28 to use the modulated linearly polarized light 35 more efficiently. It is possible.

Although the reflective spatial light modulator 22-3 shown in FIGS. 5 and 6 uses a-Si films 52 and 55, heat-resistant materials are used instead of the a-Si films 52 and 55. A polysilicon film having excellent characteristics and response characteristics can be used.

<< Reflective Spatial Light Modulator 22-4 Using MIN Element >> FIG. 7 shows, as yet another example, a partial cross section of a reflective spatial light modulator 22-4 using a MIN element. I have.

Here, 25c is a glass substrate, 60 is an insulating film, 61 is a tantalum (Ta) film electrode, and 62 is Ta ₂ O _5.
An insulating film consisting of: 63, an insulating film; 26, a metal electrode;
8 is a light shielding layer, 64 is an insulating layer, 28 is a light modulation layer, 27 is a transparent electrode common to all pixels, 30 is a transparent substrate, 35 is linearly polarized light, and 29 and 31 are antireflection films. Antireflection film 29,
It is also possible to omit 31. The electrode 26 has a size corresponding to one pixel, stores a charge amount corresponding to image information, and is driven independently for each electrode. In addition, as shown by the broken line in the figure, a dielectric multilayer mirror 49 can be formed between the electrode 26 and the light modulation layer 28, and the modulated linearly polarized light 35 can be used more efficiently. .

<< Reflection type spatial light conditioning element 22-5 having simple matrix type electrode structure >> In addition, there is a so-called simple matrix type electrode structure type spatial light conditioning element which does not use the switch 32. FIG. 8 shows an example of a reflective spatial light modulator 22-5 having a simple matrix electrode structure.

In FIG. 8, 25d is a substrate, 69 is an electrode, 28 is a light modulation layer, 27 is a transparent electrode, 30 is a transparent substrate, and 35 is a linearly polarized light. Here, the substrate 25d may be a material having either transparent or opaque optical characteristics with respect to the linearly polarized light 35. However, in the case of a substrate having characteristics that are transparent to the linearly polarized light 35, it is necessary to provide a light absorbing plate 25f that absorbs light transmitted through the substrate 25d behind the substrate 25d as shown in FIG. As shown in FIG. 8, the anti-reflection films 2 are formed on both surfaces of the transparent substrate 30.
9 and 31 can be deposited to suppress the reflection of the linearly polarized light 35. Further, it is possible to form a dielectric multilayer mirror 49 (not shown in FIG. 8) between the electrode 69 and the light modulation layer 28 to use the modulated linearly polarized light 35 more efficiently. .

<< Structure of Light Modulating Layer 28 >> The light modulating layer 28 shown in FIGS. 2 to 8 is formed by a frame-shaped sealing member sandwiched between the two-dimensional array electrode 26 and the flat transparent electrode 27. The two-dimensional array electrode 26 is formed of one or more liquid crystals selected from the group consisting of a nematic liquid crystal, a cholesteric liquid crystal, a smectic liquid crystal, or a mixture of these liquid crystals. When an image electric signal is applied to the light modulating layer 28, the electric field applied to the light modulating layer 28 changes, and the refractive index of the liquid crystal constituting the light modulating layer 28 changes. Then, linearly polarized light is incident from the plate-shaped transparent electrode 27 side, and if this is linearly polarized light having only the P component, it is directly converted into linear polarized light having only the P component according to the refractive index of the liquid crystal, P
If the linearly polarized light is linearly polarized light having only an S component, or if the linearly polarized light is linearly polarized light having only an S component, the liquid crystal is refracted. Depending on the ratio, this is converted into linearly polarized light having only the S component, or into light having an arbitrary polarization state from linearly polarized light having only the S component to linearly polarized light having only the P component. The light is reflected by the two-dimensional array electrode 26 or the dielectric multilayer film 49 provided thereon and emitted as display light.

Of the group consisting of nematic liquid crystal, cholesteric liquid crystal, smectic liquid crystal or a mixture of these liquid crystals, nematic liquid crystal is preferable because it has excellent gradation display function and response characteristics for displaying television images. In particular, when the applied voltage is small or zero and the liquid crystal molecules do not move, and the liquid crystal molecules do not move, the direction parallel to the long axis of the liquid crystal molecules is perpendicular to the surface of the plate-shaped transparent electrode 27 or deviated within several degrees from the perpendicular. Nematic liquid crystal with negative dielectric anisotropy (DAP (Deformation of Aligne
d Phase) mode liquid crystal) is preferable because a high contrast ratio can be achieved.

Further, when the applied voltage is small or zero and the liquid crystal molecules do not move, and the liquid crystal molecules are in the off state, the liquid crystal molecules are arranged in parallel with the surface of the plate-shaped transparent electrode 27 and the length of the nematic liquid crystal molecules closest to the plate-shaped transparent electrode 27 is reduced. A 45-degree twisted nematic liquid crystal having a positive dielectric anisotropy, in which the direction parallel to the axis and the direction parallel to the long axis of the nematic liquid crystal molecule farthest from the transparent substrate are arranged at an angle of 45 degrees, Since a high contrast ratio can be achieved, it is suitable for the light modulation layer 28.

To these liquid crystals, there are added ceramic particles, plastic particles, glass particles, spacers such as glass fibers, pigments, dyes, viscosity modifiers, etc. for controlling the gap between the substrates, which do not adversely affect the performance of the present invention. An agent may be added.

The operation of the reflective spatial light modulator will be described with reference to the reflective spatial light modulator shown in FIG. 2 using a DAP mode liquid crystal as the light modulating layer 28 as an example. When no electric field is applied to the DAP mode liquid crystal, the liquid crystal molecules are arranged so that the direction parallel to the long axis of the liquid crystal molecules is perpendicular to the surface of the flat transparent electrode 27 or shifted within a few degrees from perpendicular. The linearly polarized light 35 incident on the flat transparent electrode 27 perpendicularly or almost perpendicularly always feels the ordinary light refractive index no of the liquid crystal in an arbitrary polarization state. Therefore, the polarization state of the linearly polarized light does not change, and the light is specularly reflected by the two-dimensional array electrode 26 and follows the original optical path in reverse. Therefore, when no electric field is applied to the DAP mode liquid crystal, the liquid crystal enters an off state where linearly polarized light does not reach the screen.

Next, when an electric field is applied to the DAP mode liquid crystal, the liquid crystal molecules move so as to intersect the direction of the electric field. At this time, as shown in FIG.
When the electric vector of the linearly polarized light is set in a direction orthogonal to the plane and intersecting with a plane 82 including the traveling direction of the incident light at an angle of 45 degrees, the linearly polarized light 35
Feels the ordinary refractive index no in the plane 82 and the effective refractive index in the plane 81 (the refractive index depending on both the ordinary refractive index no and the extraordinary refractive index ne), so that the polarization state changes in the liquid crystal, The amount of light reaching the screen changes according to the amount of change in the polarization state, and an image is displayed.

As described above, in this embodiment, the RGB light is generated by the light source 10 of the projection display, and the RGB light is respectively converted by the white light distribution optical system 8 into the R light polarization beam splitter 9R and the G light polarization beam. Distributed to the splitter 9G and the polarization beam splitter 9B for B light,
The R light is split into the linearly polarized light having only the P component and the linearly polarized light having only the S component by the R light polarizing beam splitter 9R, and guided to the reflection type spatial light modulator 22R. Therefore, the G light is separated into linearly polarized light having only the P component and linearly polarized light having only the S component, and guided to the reflection type spatial light modulator 22G, and the B light is converted into only the P component by the polarization beam splitter 9B for B light. And the linearly polarized light having only the S component is led to the reflection type spatial light modulation elements 22B, and the light modulated by the respective reflection type spatial light modulation elements is again converted into the R light polarization beam splitter 9R. , Which are guided to the polarization beam splitter 9G for G light and the polarization beam splitter 9B for B light and converted into intensity-modulated light corresponding to the image electric signal applied to the reflection-type spatial light modulation element, thereby outputting a quarter wave for R light. Long plate 18R and 1/4 wavelength plate 1 for G light
8G and a quarter-wave plate 18B for B light, respectively.
Quarter-wave plate 18R for R light and quarter-wave plate 18G for G light
And the RGB light whose polarization state has been converted by the quarter-wave plate 18B for B light is converted into one light beam by the dichroic prism 23, and the RGB light is projected onto the screen 2 via the projection lens 24.
The B-light image is transmitted and displayed, so that the observer can see a full-color or multi-color image.

<Effects of Embodiment According to the Present Invention> As described above, the projection display 1 according to the present invention.
The white light generated from the light source 10 is decomposed into three primary color lights by a white light distribution optical system 8 including a dichroic mirror, red light is guided to the red light polarizing beam splitter 9R, and green light is converted to the green light polarized light. Guide to beam splitter 9G,
The blue light is guided to the blue light polarizing beam splitter 9B, and the red, green and blue light polarizing beam splitters 9R, 9G and 9B convert the three primary color lights into linearly polarized light having only P components. And the linearly polarized light having only the red P component or only the S component is converted into the linearly polarized light having only the red P component or only the S component.
The linearly polarized light having only the green P component or only the S component is guided to the reflective light spatial light modulator 22G for green light, and the linearly polarized light having only the blue P component or only the S component is converted to blue light. The polarization state of linearly polarized light having only the red P component or only the S component is guided to the reflective spatial light modulation element 22B and driven by the red light image electrical signal to drive the red light reflective spatial light modulation element 22R. And the reflection type spatial light modulator 2 for green light is controlled by the image electric signal for green light.
2G is driven to control the polarization state of the linearly polarized light having only the green P component or only the S component, and the blue light reflective spatial light modulator 22B is driven by the blue light image electric signal, The polarization state of the linearly polarized light having only the P component or only the S component of blue is controlled, and the modulated red light is again input to the polarization beam splitter 9R for the R light, and the linearly polarized light having only the S component or only the P component is emitted. , The modulated green light is again input to the G light polarization beam splitter 9G, and the linearly polarized light having only the S component or only the P component is selected, and the modulated blue light is again converted to the B light polarization beam splitter. 9B, linearly polarized light having only the S component or only the P component is selected, and the selected red linearly polarized light is converted into circularly polarized light or a polarization state close to circularly polarized light by the quarter-wave plate for R light 18R. Have The light is converted into elliptically polarized light, and the selected green linearly polarized light is converted into circularly polarized light or elliptically polarized light having a polarization state close to circularly polarized light by the quarter-wave plate for G light 18G. The linearly polarized light is converted into circularly polarized light or elliptically polarized light having a polarization state close to circular polarization by the quarter-wave plate for B light 18B, and converted to circularly polarized light or elliptically polarized light having a polarization state close to circular polarization. The red light, the green light and the blue light obtained are guided to the dichroic prism 23, and these three lights synthesized by the dichroic prism 23 are combined.
The primary color light is guided to the screen 2 via the projection lens 24 to display a full-color or multi-color image.

Therefore, the projection display of the present invention exhibits the following functions.

<< Function of Projection Display of the Present Invention >> FIG. 10 is a diagram for explaining the function of the projection display of the present invention. FIG. 10 shows a part of the configuration of the conventional projection display shown in FIG.
This is a part of the configuration of the projection display of the present invention incorporating the wave plates 18R, 18G, and 18B.

It is assumed that the definition of the variable indicating the intensity of the B light used in the following description is the same as that in FIG.

The B light at the passing point 400 is a linearly polarized light having the intensity Tb, and is output by the 光 wavelength plate 18B for the B light.
At the passing point 410, the light becomes circularly polarized light of intensity Tb or elliptically polarized light close to circularly polarized light. When this light passes through the dielectric multilayer mirror on the AA'C'C plane, the intensity of the noise light at the passing point 430 becomes AbTb. This light is converted by the quarter-wave plate for R light 18R into linearly polarized light having only the S component or elliptical polarized light close to it. Therefore, most of the noise light is emitted through the passing point 450 and does not affect the signal. The remaining slight light enters the red light spatial light modulator 22R and is modulated, and travels to the blue light and green light spatial light modulators 22B and 22G as indicated by broken lines.
/ Wavelength plate 18R and Ｂ wavelength plate 18B for B light, or Ｒ wavelength plate 18R for R light and 波長 wavelength plate 1 for G light
8B, the light is converted into linearly polarized light having only the S component or elliptically polarized light close to it, and the optical path is changed by the polarization beam splitter 9B for B light and the polarization beam splitter 9G for G light. I will not give.

The configuration shown in FIG. 10 has exactly the same effect for the G light and the R light, so that the imperfect reflection characteristics of the dichroic prism can be almost completely covered. Therefore, AA'C'C of dichroic prism
The reflection wavelength region of the two dielectric multilayer mirrors formed on the surface and the BB'D'D surface can be made sufficiently wide, and a bright image can be projected. Furthermore, since a high signal-to-noise ratio can be achieved without depending on the characteristics of the two dielectric multilayer mirrors, an inexpensive dichroic prism can be used.

Summarizing the above, the projection display 1 of the present invention exhibits the following effects.

<< First Effect >> First, the deterioration of the signal-to-noise ratio due to the reflection characteristics of the dielectric multilayer mirror constituting the dichroic prism can be greatly improved.

<< Second Effect >> Since the wavelength band of the RGB light incident on the dichroic prism can be made sufficiently wide, a bright image can be displayed.

<< Third Effect >> Further, since there is no need to design the reflection characteristics of the dichroic prism to a high degree, an inexpensive dichroic prism can be used.

<< Fourth Effect >> Further, in the white light distribution optical system, the wavelength range of the RGB light incident on the dichroic prism can be set without paying attention to the reflection characteristics of the dielectric multilayer mirror constituting the dichroic prism.
The design of the optical system is facilitated.

<< Fifth Effect >> By the third and fourth effects,
The manufacturing cost of the projection display can be reduced.

[0087]

As described above, according to the present invention, a quarter-wave plate for red light is inserted between a reflective spatial light modulator for red light and a dichroic prism, and a reflective spatial light for green light is provided. A 1/4 wavelength plate for green light is inserted between the modulation element and the dichroic prism, and a 1/4 wavelength plate for blue light is inserted between the reflection type spatial light modulation element for blue light and the dichroic prism.
By inserting a four-wavelength plate, a two-dimensional image such as a multi-color image or a full-color image is displayed. Since it has the configuration described in the claims, the following effects can be obtained.

(1) The deterioration of the signal-to-noise ratio due to the reflection characteristics of the dielectric multilayer mirror constituting the dichroic prism can be greatly improved.

(2) Since the wavelength band of the RGB light incident on the dichroic prism can be sufficiently widened,
A bright image can be displayed.

(3) Since there is no need to highly design the reflection characteristics of the dichroic prism, an inexpensive dichroic prism can be used.

(4) In the white light distribution optical system, the wavelength range of the RGB light incident on the dichroic prism can be set without paying attention to the reflection characteristics of the dielectric multilayer mirror constituting the dichroic prism. It will be easier.

(5) The third and fourth effects make it possible to reduce the manufacturing cost of the projection display.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of a projection display according to the present invention.

FIG. 2 is a cross-sectional view showing a configuration of a reflective spatial light modulator which is a component of the projection type stereoscopic image display device according to the present invention.

FIG. 3 is a cross-sectional view showing another configuration of a reflective spatial light modulator which is a component of the projection type stereoscopic image display device according to the present invention.

FIG. 4 is a cross-sectional view showing another configuration of a reflective spatial light modulator which is a component of the projection type stereoscopic image display device of the present invention.

FIG. 5 is a cross-sectional view showing another configuration of a reflective spatial light modulator which is a component of the projection type stereoscopic image display device of the present invention.

FIG. 6 is a cross-sectional view showing another configuration of the reflective spatial light modulator which is a component of the projection type stereoscopic image display device of the present invention.

FIG. 7 is a cross-sectional view showing another configuration of the reflective spatial light modulator which is a component of the projection stereoscopic image display device of the present invention.

FIG. 8 is a cross-sectional view showing another configuration of a reflective spatial light modulator which is a component of the projection type stereoscopic image display device of the present invention.

FIG. 9 shows a DAP liquid crystal constituting a reflective spatial light modulator which is a component of the projection type stereoscopic image display device of the present invention, and the DAP.
FIG. 4 is an explanatory diagram illustrating a relationship between electric vectors of light incident on liquid crystal.

FIG. 10 is an explanatory diagram schematically showing a configuration of a part of the configuration of the projection display of the present invention, and an optical path of B light propagating therethrough.

FIG. 11 is a configuration diagram showing a conventional projection display.

FIG. 12 is an explanatory view showing a right-angled triangular prism which is a component of the dichroic prism and a configuration of the dichroic prism.

FIG. 13 is an explanatory diagram showing the relationship between the reflectance and the wavelength of a dielectric multilayer mirror which is a component of a dichroic prism.

FIG. 14 is an explanatory diagram schematically showing a configuration of a part of a conventional projection display and an optical path of B light propagating therethrough.

FIG. 15 is an explanatory diagram showing the relationship between the transmittance Ar for R light of the dielectric multilayer mirror of the dichroic prism and the signal-to-noise ratio S / N.

[Explanation of symbols]

1: projection display of the present invention, 2: screen,
7: light source unit, 8: white light distribution optical system, 9R: polarization beam splitter for R light, 9G: polarization beam splitter for G light, 9B: polarization beam splitter for B light, 10: light source,
11: lens, 12: infrared light cut filter, 13: ultraviolet light cut filter, 14: mirror that reflects RGB light, 15: dichroic mirror that transmits R light and reflects GB light, 16: reflects G light Dichroic mirror transmitting B light, 17: mirror reflecting R light, 18R:
1/4 wavelength plate for R light, 18G: 1/4 wavelength plate for G light, 1
8B: quarter-wave plate for B light, 22R: reflective spatial light modulator for red light that modulates red linearly polarized light having only P component or only S component, 22G: only P component or only S component Green light reflective spatial light modulator for modulating green linearly polarized light, 22B: only P component or S
, 22-2, 22-3, a reflective spatial light modulator for blue light that modulates blue linearly polarized light having only components.
22-4, 22-5: reflective spatial light modulator, 23: dichroic prism, 24: projection lens, 25: substrate made of silicon or glass, 25a: silicon substrate, 25b: glass substrate, 25c: glass substrate, 25
d: substrate, 25f: light absorbing plate, 26: two-dimensional array electrode, 27: flat transparent electrode, 28: light modulation layer, 29: antireflection film, 30: transparent substrate, 31: antireflection film, 32:
Switch, 33: image electric signal supply line, 34: scanning signal supply line, 35: linearly polarized light, 40: MOS transistor,
41: source electrode line, 42: drain electrode line, 43: gate electrode line, 44, 45: insulating layer, 46: capacitor,
47: light shielding layer, 48: insulating layer, 49: dielectric multilayer mirror, 50: gate electrode, 51: SiNx insulating layer, 52: (aS
i) channel layer, 53: SiNx insulating layer, 54: source electrode, 55: n + a-Si film, 56: SiNx insulating layer, 57: drain electrode, 58: light shielding layer, 60: insulating film, 61: Ta film Electrodes, 62, 63, 64: insulating film, 69: electrode, 80: DA
P-mode liquid crystal molecules, 81: a plane including a direction parallel to the long axis of the DAP mode liquid crystal molecules, 82: a plane orthogonal to the plane 81 and including a traveling direction of linearly polarized light, 83: an electric vector of linearly polarized light, IR : Image electric signal for red light, IG: Image electric signal for green light, IB: Image electric signal for blue light.

Claims (6)

[Claims] 1. A light source for generating white light, and a white light distribution optical system including a dichroic mirror having a function of decomposing white light into three primary colors of red light, green light and blue light and distributing the light into separate optical paths. A polarizing beam splitter for red light that separates red light into linearly polarized light having only a P component and a linearly polarized light having only an S component, and a linearly polarized light having green light having only a P component that is orthogonal to each other. A polarization beam splitter for green light that separates into linearly polarized light having only S component, and a polarized light beam for blue light that separates blue light into linearly polarized light having only P component and linearly polarized light having only S component A splitter, a red spatial light modulator that converts linearly polarized light having only a red P component or linearly polarized light having only an S component into light of an arbitrary polarization state, and a green P component alone. A reflective spatial light modulator for green light that converts linearly polarized light having only S component or linearly polarized light having only S component into light of an arbitrary polarization state, and a linearly polarized light having only blue P component or only S component A reflective spatial light modulator for blue light that converts polarized light into light of an arbitrary polarization state, and a red linear polarized light emitted from a polarizing beam splitter for red light that is circularly polarized light or red that has a polarization state close to circularly polarized light And a 波長 wavelength plate for red light that converts to elliptically polarized light, and a green linearly polarized light emitted from a polarization beam splitter for green light to circularly polarized light or green elliptically polarized light having a polarization state close to circularly polarized light. A 1/4 wavelength plate for green light to be converted, and a green color for converting blue linearly polarized light emitted from a blue light polarizing beam splitter into circularly polarized light or blue elliptically polarized light having a polarization state close to circularly polarized light. A １ ／ wavelength plate for light, a dichroic prism having a function of combining three primary color lights incident from different optical paths and emitting the light from one optical path, and a projection lens for projecting the combined light. A projection display characterized by the above-mentioned. 2. The projection display according to claim 1, wherein the red spatial light modulating element is driven by a red light image electric signal, and the green spatial light modulating element is: Driving with the green light image electric signal, the blue light reflective spatial light modulator is driven with the blue light image electric signal, and again modulates the red light modulated by the red light reflective spatial light modulator. The linearly polarized light having only the red S component or the P component is guided to the red light polarizing beam splitter, and guided to the red light quarter-wave plate. The modulated green light is guided again to the green light polarizing beam splitter, and linearly polarized light having only green S component or P component is selected and guided to the green light quarter-wave plate. Modulated by reflective spatial light modulator The blue light is guided again to the blue light polarizing beam splitter, and linearly polarized light having only the blue S component or P component is selected and guided to the blue light quarter-wave plate. A circularly polarized light or a red elliptically polarized light having a polarization state close to circularly polarized light is transmitted to the dichroic mirror by passing through the four-wavelength plate, and is transmitted to the green quarter-wave plate to be circularly polarized light or circularly polarized light. Guides green elliptically polarized light having a near polarization state to the dichroic mirror, transmits the １ ／ wavelength plate for blue light, and converts circularly polarized light or blue elliptically polarized light having a polarization state close to circular polarization to the dichroic mirror Combining the three primary color lights with the dichroic prism, guiding the synthesized light to the screen via the projection lens, and displaying a full-color or multi-color image. Projection-type display that you want as the butterflies. 3. The projection display according to claim 1, wherein each of the reflective spatial light modulators comprises: a transparent substrate on which a transparent electrode is laminated; and a liquid crystal molecule which does not move when an applied voltage is small or zero. A nematic liquid crystal having a negative dielectric anisotropy in which the direction parallel to the major axis of the liquid crystal molecules is aligned perpendicular to the surface of the transparent substrate in the state or is shifted within several degrees from the vertical. A two-dimensional array electrode in contact with the light modulation layer; and electrodes arranged in a matrix for controlling the arrangement of the nematic liquid crystal for each pixel by applying a voltage to the two-dimensional array electrode. A projection type display comprising at least: a substrate having a circuit; 4. The projection display according to claim 1, wherein each of the reflective spatial light modulators includes: a transparent substrate on which a transparent electrode is stacked; and a transparent substrate when an applied voltage is in a small or zero off state. The direction parallel to the long axis of the nematic liquid crystal molecules closest to the transparent substrate and the direction parallel to the long axis of the nematic liquid crystal molecules farthest to the transparent substrate are 45 °.
A light modulating layer provided with a 45 degree twisted nematic liquid crystal having a positive dielectric anisotropy arranged at an angle of degree, a two-dimensional array electrode in contact with the light modulating layer, and the two-dimensional array electrode A substrate having electronic circuits arranged in a matrix for controlling the arrangement of the 45-degree twisted nematic liquid crystal on a pixel-by-pixel basis. 5. The projection display according to claim 1, wherein the red, green and blue quarter-wave plates are a uniaxial single crystal or a uniaxial organic compound. A projection display characterized by the above-mentioned. 6. The projection display according to claim 1, wherein the 光 wavelength plate for red light is brought into close contact with the polarizing beam splitter or dichroic prism for red light,
The た wavelength plate for green light was adhered to the polarizing beam splitter or dichroic prism for green light, and the 波長 wavelength plate for blue light was adhered to the polarizing beam splitter or dichroic prism for blue light. A projection display characterized by the following.