JP2004198999A - Projection type display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projection type display device using a reflection type light valve capable of yielding a projected image excellent in white balance and contrast. <P>SOLUTION: The projection type display device is provided with a light source 201, a color separation optical system color-separating a light beam from the light source to three color light beams, three reflection type light valves arranged for respective color light beams, three polarizing beam splitters having a polarizing separation part for respectively polarizing and separating the three color light beams from the color separation optical system and guiding the light beams to the reflection type light valves, and respectively analyzing the three color light beams modulated by the reflection type light valves, a color compositing optical system color-compositing the three color light beams analyzed by the three polarizing beam splitters, and a projection lens projecting the composited light beam from the color compositing optical system. A light quantity adjusting member is arranged in the optical path of at least one color light beam out of the three color light beams. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a projection display device using a plurality of reflective light valves.
[0002]
[Prior art]
Light valves are respectively arranged for red light, green light, and blue light (hereinafter, referred to as R light, G light, and B light, respectively) to adjust the white balance of each color light as a whole. In order to be able to secure the light, the light enters the light valve for each color light via the ND filter for adjusting the light amount, modulates based on each color signal, and modulates the light emitted from the light valve into a color and projects it with the projection lens. There is known a transmissive projection display device having such a configuration (see Patent Document 1).
[0003]
In the projection display device disclosed in Patent Document 1, R light, G light, and B light emitted from each light source adjust the amount of transmitted light as light amount adjusting means arranged perpendicular to the optical axis of each color light. The ND filter for each color light is made, the white balance is adjusted, the light is transmitted to the transmission type liquid crystal light valves arranged for each color light, and the modulated light is emitted based on the color signal of each color light. It has a configuration in which light having good white balance is made to emit light after being incident on a cross dichroic prism constituting a color synthesizing optical system, and projected from a projection lens.
[0004]
[Patent Document 1]
JP-A-5-313114 (see FIG. 5)
[0005]
[Problems to be solved by the invention]
However, in a projection type display device using a reflection type light valve, by arranging a light amount adjustment member such as an ND filter in an optical path, a white balance can be adjusted well and a projection that improves the contrast of a projected image can be achieved. Type display devices have not been proposed.
[0006]
The present invention has been made in view of the above-described problems, and has as its object to provide a projection display apparatus using a reflective light valve capable of obtaining a projection image with good white balance and contrast.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a light source, a color separation optical system that separates light from the light source into light of three colors of a first color light, a second color light, and a third color light; First, second, and third reflective light valves arranged corresponding to the light beams of the colors, respectively, and the light beams of the three colors from the color separation optical system are polarized and separated, respectively. A polarization separation unit for guiding the light of the three colors guided to the second and third reflective light valves and detecting the light of the three colors modulated by the first, second, and third reflective light valves, respectively. A first, a second, and a third polarizing beam splitter; a color combining optical system for combining colors of the three colors of light detected by the first, second, and third polarizing beam splitters; A projection lens for projecting the combined light from the combining optical system, and reducing the amount of the three color lights. Also to provide a projection type display apparatus characterized by disposing the light amount adjustment member in the optical path of one color beam.
[0008]
In the projection display device according to the aspect of the invention, it is preferable that the light amount adjusting member is disposed in an optical path between the polarization beam splitter disposed corresponding to the color light and the color separation optical system. .
[0009]
In the projection display device according to the aspect of the invention, it is preferable that the light amount adjusting member includes a wavelength phase plate that changes a state of incident polarized light and a polarizing plate.
[0010]
Further, in the projection display device of the present invention, it is preferable that the polarizing plate is a wire grid metal polarizing plate or a polarizing plate attached to a sapphire substrate. Preferably, the adjustment member is composed of a plurality of absorption ND filters.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0012]
FIG. 1 is a schematic configuration diagram of a projection display device according to a first embodiment of the present invention. FIG. 2 is a schematic configuration diagram of a projection display device according to a second embodiment of the present invention, and FIG. 3 illustrates the arrangement of a half-wave phase plate and a polarizing plate that are light amount adjusting members in the second embodiment. It is a perspective view. FIG. 4 is a schematic configuration diagram of a projection display device according to a third embodiment of the present invention.
[0013]
(1st Embodiment)
FIG. 1 is a schematic configuration diagram showing a first embodiment of a projection display device of the present invention. In FIG. 1, an X axis, a Y axis, and a Z axis that are orthogonal to each other are defined. Note that the Y axis is a direction perpendicular to the paper surface.
[0014]
In FIG. 1, a randomly polarized light source light emitted from a light source 101 composed of a lamp 101a and a concave mirror 101b such as a parabolic mirror changes its vibration direction parallel to the Y-axis direction perpendicular to the paper by a polarization conversion device 101c. Is converted to linearly polarized light. The polarized light is incident on a dichroic mirror 102 having transmission characteristics for B light (blue light) and reflection characteristics for R light (red light) and G light (green light). The light is color-separated into light and mixed light of G light and R light. Among the color lights separated by the dichroic mirror 102, the B light is incident on an ND filter 109B, which is a light amount adjustment member disposed orthogonal to the optical axis of the B light, and is emitted after adjusting the amount of transmitted light. The light enters the polarization beam splitter 104B.
[0015]
On the other hand, the mixed light of the R light and the G light separated by the dichroic mirror 102 is incident on the dichroic mirror 103 having a characteristic of reflecting the G light and transmitting the R light, and is transmitted through the reflected G light and proceeds. Is separated into R light. The color-separated G light is incident on an ND filter 109G, which is a light amount adjusting member disposed perpendicular to the XZ plane and orthogonal to the optical axis of the G light. It is incident on 104G. The color-separated R light is incident on an ND filter 109R, which is a light amount adjustment member disposed perpendicular to the XZ plane and perpendicular to the optical axis of the R light, and is transmitted with its transmitted light amount adjusted and emitted. The light enters the beam splitter 104R. Note that the dichroic mirror 102 and the dichroic mirror 103 constitute a color separation optical system. The white balance can be improved by adjusting the light amount of each color light by the ND filter.
[0016]
The white-balanced incident lights respectively incident on the polarization beam splitters 104B, 104G, and 104R are reflected by the respective polarization splitters 104BP, 104GP, and 104RP, and travel to the respective polarization beams. The light is emitted from the splitters 104B, 104G, and 104R, respectively, and is incident on the light valves 105B, 105G, and 105R arranged for the respective color lights. The incident light is modulated and reflected by the light valves 105B, 105G, and 105R for the respective color lights. The light whose polarization direction is rotated by 90 degrees (parallel to the X-axis or the Z-axis with respect to the paper surface) by the modulation is emitted from the light valve, and is again transmitted to the polarization beam splitters 104B, 104G, and 104R for each color light. Each is incident. The incident modulated light is detected by the polarization splitters 104B-P, 104GP, and 104R-P, respectively, and taken out as the detected light, and the R light and the G light are incident on the dichroic mirror 106 that performs color synthesis. Then, the R light is transmitted and the G light is reflected to be a mixed light of the R light and the G light and emitted. The emitted mixed light is combined with the B light by the dichroic mirror 107 to achieve color synthesis and is emitted. The combined light enters the projection lens 108, and projects a full-color projection image on a screen (not shown). Thus, a reflective display device is configured.
[0017]
By employing such an arrangement, it is possible to project a projection image with good white balance and good contrast. In the present embodiment, the R light, the G light, and the Although the ND filters, which are the light amount adjusting members, are arranged in the optical paths of the B light components, it is not necessary to dispose these ND filters in all the color light components due to the design of the color separation optical system. An ND filter may be arranged for two colors of light of the three colors of R light, G light and B light, or may be arranged for only one color light. Which color light should be provided with these members may be appropriately determined depending on the design and manufacture of the color separation optical system.
[0018]
(2nd Embodiment)
FIG. 2 is a schematic configuration diagram showing a second embodiment of the projection display device of the present invention. In FIG. 2, an X axis, a Y axis, and a Z axis orthogonal to each other are defined. Note that the Y axis is a direction perpendicular to the paper surface.
[0019]
In FIG. 2, a randomly polarized light source light emitted from a light source 201 composed of a lamp 201 a and a concave mirror 201 b such as a parabolic mirror changes a vibration direction parallel to a Y-axis direction perpendicular to the paper surface by a polarization conversion device 202. Is converted to linearly polarized light. A dichroic mirror 203B having reflection characteristics for the B light (blue light) and a dichroic mirror 203RG having reflection characteristics for R light (red light) and G light (green light) are orthogonal to each other. B light, which is parallel to the Z axis and travels in opposite directions with respect to the center of the cross dichroic mirror 203, and a mixed light of G light and R light. Color separation. Among the color lights separated by the dichroic mirror 203, the B light is incident on the bending mirror 204 and travels in a different traveling direction, and is predetermined with respect to a direction perpendicular to the XZ plane and having an optical axis parallel to the Y axis. The amount of transmitted light is adjusted by a light amount adjusting member composed of a 波長 wavelength phase plate 212B arranged at an angle of and a polarizing plate 213B having an optical axis parallel to the Y-axis direction. 208B.
[0020]
On the other hand, the mixed light of the R light and the G light color-separated by the cross dichroic mirror 203 is incident on the bending mirror 205, changes its traveling direction, travels, and reflects the G light and transmits the R light. The light is incident on the light 206, and is color-separated into the reflected G light and the R light that transmits and travels. The color-separated G light is a half-wave phase plate 212G arranged perpendicularly to the XZ plane and at a predetermined angle with respect to the direction parallel to the Y axis, and an optical axis parallel to the Y axis. The transmitted light amount is adjusted by a light amount adjusting member composed of a polarizing plate 213G having an axis, and the light is emitted and enters the polarization beam splitter 208G. The color-separated R light is parallel to the Y-axis direction with a half-wave phase plate 212R arranged perpendicular to the XZ plane and at a predetermined angle with respect to the direction parallel to the Y-axis. The amount of transmitted light is adjusted by a light amount adjusting member composed of a polarizing plate 213R having an appropriate optical axis, and the light is emitted and enters the polarization beam splitter 208R. The cross dichroic mirror 203, the bending mirrors 204 and 205 and the dichroic mirror 206 constitute a color separation optical system.
[0021]
The white-balanced incident light incident on each of the polarization beam splitters 208B, 208G, and 208R is reflected by each of the polarization splitters 208B-P, 208G-P, and 208R-P, and travels. The light is emitted from the splitters 208B, 208G, and 208R, respectively, and enters the light valves 209B, 209G, and 209R arranged for the respective color lights. The incident light is modulated by the light valves 209B, 209G, and 209R for the respective color lights, reflected and emitted, and re-enters the polarization beam splitters 208B, 208G, and 208R for the respective color lights again. The incident modulated light is detected by the polarization splitters 208B-P, 208GP, and 208R-P, respectively, taken out as the analyzed light, and is incident on the cross dichroic prism 210 that performs color synthesis from different incident surfaces. I do. The Croiss dichroic prism 210 is a composite prism in which an R light reflecting dichroic film 210R and a B light reflecting dichroic film 210B are arranged orthogonally (X type), and the incident B light reflects the B light reflecting dichroic film 210B. Then, the incident R light is reflected by the R light reflecting dichroic film 210R, and the incident G light is transmitted through both dichroic films 210B and 210R to achieve color synthesis. The combined light exits the cross dichroic prism 210, enters the projection lens 211, and projects a full-color projection image on a screen (not shown). Thus, a reflective display device is configured.
[0022]
FIG. 3 is an exploded perspective view of a light amount adjusting member including a half-wave phase plate 212G and a polarizing plate 213G inserted in the optical axis of the G light. Since the light amount adjusting members for the R light and the B light have the same structure, only the G light is described here, and the description of the R light and the B light is omitted.
[0023]
In FIG. 3, the direction of polarization of the G light incident on the half-wave phase plate 212G is linearly polarized light having a vibration direction parallel to the Y axis at the position shown in FIG. The direction 光学 of the optical axis D1 of the half-wave phase plate 212G has a predetermined angle of, for example, about 20 to 30 degrees with respect to this vibration direction. The light at the position (B) incident on and emitted from the half-wavelength phase plate 212G is linearly polarized light having a vibration direction in a direction at an angle of 2 ° with respect to the Y-axis direction. This linearly polarized light is emitted by the polarizing plate 213G as a predetermined amount of light as linearly polarized light having a vibration direction in the Y-axis direction, and a part thereof is absorbed by the polarizing plate 213G. By the combination of the half-wave phase plate 212G and the polarizing plate 213G, the light amount of the G light is adjusted, and the light amount with white balance is transmitted and emitted. At the position (C), the vibration direction in which the light amount is adjusted is on the Y axis. It is parallel linearly polarized light. This linearly polarized light enters the polarization beam splitter 208G and is polarized in a direction substantially reflected by the polarization separation unit 208G-P. Therefore, the linearly polarized light is reflected by the polarization separation unit 208G-P, exits the polarization beam splitter 208G, and emits light. 209G. The light that has entered the light valve 209G is modulated and reflected and emitted, and then enters the polarization beam splitter 208G again. The modulated light is extracted as transmitted light that has passed through the polarization splitter 208GP. The unmodulated light that has not been modulated by the light valve 209G is separated as reflected light from the polarization separation unit 208GP.
[0024]
In the second embodiment, as described above, the amount of polarized light passing through the polarizing beam splitter 208G and entering the light valve 209G is adjusted by absorbing unnecessary light with the polarizing plate 213G. . In order to obtain a high-brightness projected image, the amount of G light incident on the half-wave phase plate 212G and the polarizing plate 213G must be increased, and the performance of the polarizing plate 213G deteriorates due to heat generation due to light absorption. There is a possibility that it will end up. When the polarizing plate 213G may absorb light to such an extent that the performance may be deteriorated, the polarizing plate 213G is not a polarizing plate made of a normal organic material, but a metal polarizing plate having a wire grid structure with a large heat resistance effect. It is preferable to use a polarizing plate having a structure in which a polarizing plate is attached to a sapphire substrate having a large heat dissipation effect.
[0025]
Further, the half-wave phase plate 212R and the polarizing plate 213R for R light, and the half-wave phase plate 212G and the polarizing plate 213G for G light have the same arrangement. However, since the light amount of each color light is adjusted to secure white balance, the inclination of the optical axes of the half-wavelength phase plates 212R, 212G, and 212B with respect to the direction parallel to the Y axis is determined according to each color light. Need to be done.
[0026]
In the second embodiment, when the light valve is in the black state, the half-wavelength phase plate and the polarizing plate are reflected and emitted from the light valve, and are reflected and returned from the polarization splitter of the polarization beam splitter. Although the light reflected by the polarizing plate and the half-wavelength phase plate cannot be said to be zero, the amount of reflected light is very small compared to the amount of light transmitted through the half-wavelength phase plate and the polarizing plate. The amount of light that returns to the polarizing beam splitter again and enters the light valve is a light amount that can be almost ignored. For this reason, the half-wave phase plate and the polarizing plate can be arranged to be perpendicular to the optical axis of each color light, and the projection is performed with better white balance and better contrast than the first embodiment. A projection display device for projecting an image can be provided.
[0027]
In the second embodiment, the wavelength phase plates arranged for the respective color lights are 波長 wavelength phase plates, but the wavelength phase plate to be used is not limited to the 波長 wavelength phase plate. For example, it is also possible to arrange another wavelength phase plate, convert the light into, for example, elliptically polarized light, enter the polarizing plate, and adjust the amount of light. As another wavelength phase plate, for example, a quarter wavelength phase plate can be used.
(Third embodiment)
Next, a projection type display device according to a third embodiment of the present invention will be described.
[0028]
FIG. 4 is a schematic configuration diagram of a projection display device according to a third embodiment of the present invention. The third embodiment is different from the second embodiment in that a plurality of absorption ND filters, which are light amount adjusting members, are disposed in the optical paths of the respective color lights. The basic configuration has the same configuration as that of the second embodiment, and the same components are denoted by the same reference numerals and description thereof will be omitted.
[0029]
In FIG. 4, the absorption ND filters 214R and 215R for R light, the absorption ND filters 214G and 215G for G light, and the absorption ND filters 214B and 215B for B light are polarization beam splitters 208R for each color light, A projection type display device is arranged close to the color separation optical system side entrance surfaces of 208G and 208B and arranged perpendicularly to the XZ plane and the optical axis of each color light.
[0030]
In the third embodiment, a plurality of absorption-type ND filters, which are light amount adjustment members, are arranged in the optical path of each color light. As a result, the amount of light absorbed as a whole can be distributed to each ND filter, and performance degradation due to heat generation of each ND filter can be prevented.
[0031]
When the light valves 209B, 209G, and 209R for the respective color lights are in the black state, the light reflected and emitted from the respective light valves 209B, 209G, and 209R almost enters the polarization beam splitters 208B, 208G, and 208R, respectively. , Respectively, and enter the absorption type ND filters 214B and 215B, 214G and 215G, and 214R and 215R for each color light. Since the ND filters 214B and 215B, 214G and 215G, and 214R and 215R are absorption types, most of the light is absorbed or transmitted, so that the ND filters 214B and 215B, 214G and 215G, and 214R and 215R reflect, respectively. There is almost no backward light. As a result, light incident on the light valves 209B, 209G, and 209R of the respective color lights via the polarization beam splitters 208B, 208G, and 208R can be substantially eliminated. Therefore, it is possible to maintain good contrast of the projection light.
[0032]
Since the respective incident lights are reflected by the light valves 209B, 209G, and 209R, respectively, are incident on the ND filters 214B and 215B, 214G and 215G, and 214R and 215R, respectively. And 215G, and 214R and 215R are not sufficient for only the respective color lights that are separated and incident, and it is necessary to take the respective return lights from the light valves 209B, 209G, and 209R into consideration. . In the third embodiment, a configuration is used in which a plurality of absorption ND filters are used.
[0033]
In the third embodiment, for at least one color light, a plurality of absorption ND filters are arranged in the optical path near the color-separation optical system-side incident surface of the polarizing beam splitter, so that the height is higher than that of the first embodiment. It is possible to project a projection image with good luminance, good white balance, and good contrast.
[0034]
In the third embodiment, two absorption-type ND filters are arranged for each color light, however, it is needless to say that the number of absorption-type ND filters may be more.
[0035]
Further, in the third embodiment, a plurality of absorption ND filters are arranged for each color light, however, depending on the design and manufacture of the color separation optical system, the arrangement may be an arrangement of only one color light or an arrangement of two color lights. It may be configured.
[0036]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a projection type display device using a reflection type light valve capable of obtaining a projection image with good white balance and contrast.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a projection display device according to a first embodiment of the present invention.
FIG. 2 is a schematic configuration diagram of a projection display device according to a second embodiment of the present invention.
FIG. 3 is a perspective view illustrating an arrangement of a half-wave phase plate and a polarizing plate, which are light amount adjusting members according to a second embodiment.
FIG. 4 is a schematic configuration diagram of a projection display device according to a third embodiment of the present invention.
[Explanation of symbols]
104R, 104G, 104B Polarization beam splitters 105R, 105G, 105B Reflection type light valves 109R, 109G, 109B ND filters 101, 201 Light sources 101c, 202 Polarization conversion devices 203 Cross dichroic mirrors 204, 205 Optical path bending mirrors 102, 103, 106, 107, 206 Dichroic mirrors 207R, 207G, 207B ND filters 208R, 208G, 208B Polarizing beam splitters 209R, 209G, 209B Reflective light valve 210 Cross dichroic prism 108, 211 Projection lenses 212R, 212G, 212B 1/2 wavelength phase plate 213R , 213G, 213B Polarizing plate 214R, 214G, 214B, 215R, 215G, 215B Absorption ND filter

Claims (5)

A light source,
A color separation optical system that separates light from the light source into light of three colors of first color light, second color light, and third color light;
First, second, and third reflective light valves arranged corresponding to the three colors of light, respectively;
The three color lights from the color separation optical system are polarized and separated, respectively, and guided to the first, second, and third reflective light valves, and the first, second, and third reflective lights are provided. First, second, and third polarization beam splitters each having a polarization separation unit for detecting each of the three colors of light modulated by the valve;
A color combining optical system that combines the three colors of light detected by the first, second, and third polarizing beam splitters;
A projection lens for projecting synthesized light from the color synthesis optical system,
A projection display device, wherein a light amount adjusting member is disposed in an optical path of at least one of the three color lights. 2. The projection display device according to claim 1, wherein the light amount adjusting member is arranged in an optical path between the polarization beam splitter arranged corresponding to the color light and the color separation optical system. 3. 3. The projection display device according to claim 1, wherein the light amount adjustment member includes a wavelength phase plate that changes a state of incident polarized light, and a polarizing plate. 4. 4. The projection display according to claim 3, wherein the polarizing plate is a wire grid metal polarizing plate or a polarizing plate attached to a sapphire substrate. The projection display device according to claim 1, wherein the light amount adjustment member includes a plurality of absorption ND filters.

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