JPH07270747A - Projection type display device - Google Patents

Abstract

PURPOSE:To obtain a projection type display device whose irregular color is little and whose white balance is excellent by optically adjusting illuminance distribution on a plane on plural liquid crystal light valves. CONSTITUTION:An illuminating light beam 100 emitted from a light source 1 passes through a filter 4, so that only visible light component is obtained and separated to three R, G and B monochromatic light beams 100R, 100G and 100B by 1st and 2nd dichroic mirrors 5a and 5b, and radiated to the liquid crystal light valves 7R, 7G and 7B displaying a corresponding monochromatic image through illuminance distribution adjusting elements 21R, 21G and 21B. Luminous fluxes modulated by the image formed on the light valves 7R, 7G and 7B are synthesized into one luminous flux by a dichroic prism 8 and made incident on a projection lens 9. The luminous flux passing through the lens 9 becomes the projected light beam 101 and enlarged and formed as the projected image on a screen 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color unevenness correction and a white balance correction of a projection type display device which synthesizes images formed on a plurality of light valves and enlarges and projects them on a screen.

[0002]

2. Description of the Related Art At present, an illumination light flux emitted from a predetermined light source is decomposed into three primary color lights of R (red), G (green) and B (blue), and then these illumination light fluxes are divided into R, G, and A projection display device has been put into practical use in which an image is formed by being incident on each liquid crystal light valve for B, and then each image of R, G, and B is combined and enlarged and projected on a screen.

FIG. 12 is an explanatory diagram of an optical system of a projection type display device using a conventional liquid crystal light valve. In the figure,
Reference numeral 1 is a light source, 2 is a lamp, 3 is a reflecting mirror, 100 is illumination light emitted from the light source 1, 4 is a filter that transmits only a visible light region, 5a and 5b are first and second dichroic that reflect a specific wavelength. Mirrors, 6a, 6b and 6c are reflection mirrors, 7R, 7G and 7B are liquid crystal light valves, 8 is a dichroic prism for combining colors, 9 is a projection lens, 10
Is the screen.

Next, the operation will be described. The light source 1 includes a lamp 2 and a reflecting mirror 3, and emits illumination light 100. As the lamp 2, a white light source such as a metal halide lamp, a xenon lamp, a halogen lamp or the like is used. The reflecting surface of the reflecting mirror 3 is typically a parabolic surface, and by arranging the light emission center of the lamp at the focal point of the parabolic surface, it is possible to obtain substantially parallel illumination light 100, as is well known. The illumination light 100 first passes through the filter 4 to become only a visible light component, and the liquid crystal light valve 7
Prevents characteristic deterioration due to ultraviolet rays and infrared rays (heat rays). The illumination light 100 transmitted through the filter 4 is red-reflected by a first dichroic mirror 5a that reflects red light and transmits green / blue light and a second dichroic mirror 5b that reflects green light and transmits red light. A liquid crystal light valve 7 that decomposes into three monochromatic lights 100R, 100G, and 100B of green and blue, and the optical paths are bent by the reflection mirrors 6a, 6b, and 6c to display a monochromatic image corresponding to each primary color.
It is irradiated to R, 7G, and 7B. The liquid crystal light valve 7
The light fluxes modulated by the images formed on R, 7G, and 7B are combined again into a single light flux by a known dichroic prism 8 that selectively reflects red and blue light and selectively transmits green light. The light enters the projection lens 9 and
The light flux that has passed through becomes the projection light 101 and becomes the screen 10
The image is enlarged and projected as a projected image on the upper side for viewing.

[0005]

However, the conventional projection display device as described above has the following problems. Now, assuming that the intervals between the dichroic mirror and the reflecting mirror are equal, the red light 100R and the green light 100G are reflected or transmitted by the first dichroic mirror 5a and then respectively reflected by the reflecting mirror 6a.
Since the optical path is bent by the second dichroic mirror 5b, the optical path lengths to the liquid crystal panel become almost equal. On the other hand, the blue light 100B is transmitted through the second dichroic mirror 5b even after the two reflection mirrors 6b,
Since the optical path is bent at 6c, the optical path length to the liquid crystal panel becomes longer than the other two primary color lights 100R and 100G.

Next, the illumination light 100 emitted from the light source 1
The illuminance distribution on the liquid crystal light valve 7 will be described. Since the illumination light 100 is not a perfect parallel light due to the existence of the arc length of the lamp, the illuminance distribution varies depending on the distance from the light source 1. Now, red light 100R, green light 100
It is assumed that the illuminance E on the liquid crystal light valves 7R, 7G, and 7B corresponding to each monochromatic light of G and blue light 100B has the distribution shown in FIG. In FIG. 13, the horizontal axis represents the relative image height, and illuminance unevenness occurs in which the light is bright in the central portion and dark in the peripheral portion for each primary color light. In the central portion, the red light 100R and the green light 100G are relatively stronger than the blue light 100B, and conversely, in the peripheral portion, the blue light 100B is the red light 100R and the green light 1.
Since the intensity of the light is relatively stronger than that of 00G, the central portion emits yellowish white light, and a projected image with large color unevenness is observed.

The above liquid crystal light valves 7R, 7G, 7
As a method of correcting the color unevenness caused by the illuminance unevenness of the luminous fluxes 100R, 100G, and 100B that illuminate B, there is a method of electrically adjusting the transmittance of each pixel of the liquid crystal light valve 7. Using a video signal correction circuit (not shown),
The light fluxes illuminating each pixel are compared within the plane of each liquid crystal light valve 7R, 7G, 7B, and each liquid crystal light valve 7R, 7R
An illuminance distribution correction signal is given so that the illuminance distributions of G and 7B are equal. For example, red and green liquid crystal light valves 7
The liquid crystal light valves 7R and 7G are arranged so that the illuminance distributions of R and 7G are equal to those of the blue liquid crystal light valve 7B.
It suffices to adjust the gain or offset voltage so that the transmittance of the pixel in the central part of is low.

In order to obtain a desired white chromaticity,
It is necessary to balance the red, green, and blue illumination lights 100R, 100G, and 100B. Similar to the above, the video signal is set so that the transmittance of each pixel of the liquid crystal light valve with relatively strong illumination light is lower than the transmittance of each pixel of the liquid crystal light valve with relatively weak illumination light. A white balance correction signal is given from a correction circuit (not shown). For example,
When the green illumination light 100G is relatively strong, the gain or offset voltage may be adjusted so that the transmittance of each pixel of the green liquid crystal light valve 7G becomes low as a whole.

However, since the transmittance of the liquid crystal light valve is electrically controlled in order to adjust the color unevenness and the white balance, the liquid crystal light valve with a large amount of correction is responsible for a considerable part of the gray scale display capability that originally exists. When used for the illuminance distribution correction signal and the white balance correction signal, there is a problem that the gradation is deteriorated and the SN ratio is deteriorated, resulting in deterioration of the image quality.

The present invention has been made to solve the above-mentioned problems, and by optically correcting the illuminance distribution on the liquid crystal light valve, the color unevenness is small and the white balance is good. It is an object to provide a projection display device.

[0011]

According to a first aspect of the present invention, there is provided a projection type display device comprising a light valve for forming three monochromatic images corresponding to respective primary colors of red, green and blue, and the light valve. A projection lens for enlarging and projecting the image formed on the light source, a light source for illuminating the light valve to emit a substantially parallel light beam, and an illumination light beam of substantially parallel light emitted from the light source for the red light.
A color separation mirror for separating the three primary colors of green and blue,
In a projection type display device having an optical system composed of a color synthesizing prism or a color synthesizing mirror for forming an image on the light valve and then synthesizing the light beams again, each light corresponding to red, green and blue. At least one illuminance distribution adjusting element capable of controlling the in-plane illuminance distribution of a light beam illuminating the light valve is provided in an optical path passing through the bulb.
It is arranged in one optical path.

According to a second aspect, the illuminance distribution adjusting element is formed by forming halftone dots smaller than the pixel size of the light valve.

Further, in the present invention, the illuminance distribution adjusting element is arranged outside the depth of field region of the projection lens so that the halftone dots in the illuminance distribution adjusting element do not form an image on the image plane of the projection image. Is.

Further, according to a fourth aspect of the present invention, the light incident surface and the light emitting surface of the illuminance distribution adjusting element are provided with a non-reflection coating according to the spectral characteristics of each illumination luminous flux.

Further, in claim 5, a light valve for forming three monochromatic images corresponding to respective primary colors of red, green and blue;
A projection lens that magnifies and projects the image formed on the light valve, a light source that emits a substantially parallel light beam that illuminates the light valve, and an illumination light beam of substantially parallel light that is emitted from the light source of the red, green, and blue light. Projection-type display having a color separation mirror for separating into three primary colors and an optical system including a color combining prism or a color combining mirror for forming an image on the light valve and then combining the light beams again into one light beam In the device, at least one white balance adjusting element capable of controlling the ratio of the luminous flux illuminating the light valves is arranged in the optical path passing through the light valves corresponding to red, green and blue.

According to a sixth aspect of the present invention, the white balance adjusting element uses a transmission / scattering mode light valve capable of continuously selecting from a transparent state to an opaque state according to an applied voltage.

Further, according to a seventh aspect of the present invention, the light incident surface of the white balance adjusting element is provided with a non-reflective coating according to the spectral characteristics of each illumination luminous flux.

Further, in claim 8, the white balance adjusting element has a moving means capable of shifting the white balance adjusting element back and forth in the optical axis direction.

Further, in claim 9, a light valve for forming three monochromatic images corresponding to respective primary colors of red, green and blue;
A projection lens that magnifies and projects the image formed on the light valve, a light source that emits a substantially parallel light beam that illuminates the light valve, and an illumination light beam of substantially parallel light that is emitted from the light source of the red, green, and blue light. The optical system includes a color separation mirror for separating into three primary colors, and a color combining prism or a color combining mirror for forming an image on the light valve and then combining the light beams again into one light beam. In a projection display device in which a white balance adjusting element capable of controlling the ratio of luminous flux illuminating the light valve is arranged in an optical path passing through the light valve, the white light is projected on the screen when white light is projected on the screen. The chromaticity detecting means capable of detecting the chromaticity of the projected image and the circuit for controlling the white balance adjusting element according to the output of the detecting means.

According to a tenth aspect of the invention, a light valve for forming three monochromatic images corresponding to each of the primary colors of red, green and blue, a projection lens for enlarging and projecting the image formed on the light valve, A light source that emits a substantially parallel light beam that illuminates the light valve, a color separation mirror that separates the illumination light beam of the substantially parallel light that is emitted from the light source into the three primary colors of red, green, and blue, and the light valve. 1 again after forming the image
It is possible to control the ratio of the luminous flux illuminating the light valve in the light path that passes through the color synthesizing prism or color synthesizing mirror for synthesizing the light flux of the book and each light valve corresponding to red, green, and blue. A projection display device having an optical system including a white balance adjusting element has a removing means for disposing the white balance adjusting element outside the optical path.

[0021]

In the projection type display device according to the present invention configured as described above, in claim 1, the in-plane illuminance to each light valve irradiated from the light source in the optical path passing through any light valve. By arranging an illuminance distribution adjusting element having different transmission characteristics in the central part and the peripheral part corresponding to the distribution, the illuminance distribution adjusting element works so that the illuminance distribution ratio among a plurality of light valves becomes equal, and the unevenness of color It is possible to display a small image.

According to the present invention, the illuminance distribution adjusting element is formed by forming halftone dots smaller than the pixel size of the light valve, so that the halftone dots in the illuminance distribution adjusting element form a projected image. It is prevented from being resolved on the image plane.

Further, in the present invention, the illuminance distribution adjusting element is arranged outside the depth of field region of the projection lens so that the halftone dots in the illuminance distribution adjusting element are connected to the image plane of the projected image. Prevent the image.

Furthermore, in the present invention, the light incident surface and the light emitting surface of the illuminance distribution adjusting element are provided with a non-reflective coating to prevent Fresnel reflection on the surface of the illuminance distribution adjusting element.

Further, according to the present invention, by disposing a white balance adjusting element capable of controlling an in-plane illumination luminous flux in an optical path that passes through an arbitrary light valve, the white balance adjusting element is provided with a plurality of white balance adjusting elements. The illumination light flux ratio between the light valves works so as to obtain a value of good white chromaticity, and it is possible to display a projection image with good white chromaticity.

Further, in the present invention, by using a transmission / scattering mode light valve as the white balance adjusting element, the transmitted light flux to each light valve is controlled by the voltage applied to the transmission / scattering mode light valve. be able to.

Further, in the present invention, the light incident surface of the white balance adjusting element is provided with a non-reflective coating to prevent Fresnel reflection on the surface of the white balance adjusting element.

Further, according to the eighth aspect, by shifting the white balance adjusting element back and forth in the optical axis direction, it is possible to finely adjust the luminous flux entering the diaphragm of the projection lens.

According to a ninth aspect of the present invention, there is provided a chromaticity detecting means capable of detecting the chromaticity of the projected image, and a circuit for controlling the white balance adjusting element according to the output of the detecting means. The white balance adjusting element works to maintain the chromaticity of the projected image.

According to the tenth aspect of the present invention, since the white balance adjusting element is provided with a removing means which can be arranged outside the optical path, the removing means is provided outside the optical path when the white balance adjusting element is unnecessary. It works to suppress the loss of the illumination light flux due to the arrangement and transmission through the white balance adjusting element.

[0031]

【Example】

Example 1. First Embodiment FIG. 1 is a configuration diagram showing an optical system of a projection display device according to a first embodiment of the present invention. In the figure, 1 is a light source, 2 is a lamp, 3 is a reflecting mirror, 100 is illumination light emitted from the light source 1, 4 is a filter which transmits only a visible light region,
Reference numerals 5a and 5b are first and second dichroic mirrors that reflect a specific wavelength, 6a, 6b and 6c are reflection mirrors, and 21.
R, 21G, 21B are illuminance distribution adjusting elements, 7R, 7G,
7B is a liquid crystal light valve, 8 is a dichroic prism for combining colors, 9 is a projection lens, and 10 is a screen.

First, the operation of the above embodiment will be described. In FIG. 1, the lamp 1 is a metal halide lamp,
A white light source such as a xenon lamp or a halogen lamp is used. The reflecting mirror 3 is a parabolic mirror having a focal position at the light emitting point of the lamp 2, and the reflecting surface of the parabolic mirror has a coating (eg, 700 [nm] or more) that transmits infrared light as necessary. Is transmitted to reduce the proportion of heat radiated to the liquid crystal light valve side. Of the light flux emitted from the lamp 2, the light flux reflected by the parabolic mirror 3 becomes an illumination light flux 100 of substantially parallel light and enters the filter 4. The filter 4
Transmits only visible light and reflects or absorbs unnecessary infrared / ultraviolet light (eg, transmits the wavelength band of 400 to 700 [nm])
To do.

The illumination light 100 transmitted through the filter 4 is incident on the first dichroic mirror 5a. The dichroic mirror 5a reflects the red light 100R and reflects the green light 1R.
00G and blue light 100B are transmitted. Red light 100R
Is radiated to the liquid crystal light valve 7R via the illuminance distribution adjusting element 21R after the optical path is bent by the reflection mirror 6a. The green light 100R and the blue light 100B that have passed through the first dichroic mirror 5a enter the second dichroic mirror 5b. The dichroic mirror 5b reflects the green light 100G and transmits the blue light 100B. The green light 100G is applied to the liquid crystal light valve 7G via the illuminance distribution adjusting element 21G. The blue light 100B transmitted through the second dichroic mirror 5b has its optical path bent by the two reflection mirrors 6b and 6c, and is applied to the liquid crystal light valve 7B via the illuminance distribution adjusting element 21B.

Light fluxes 100R, 100G, 10 modulated by the image formed on the liquid crystal light valves 7R, 7G, 7B.
0B selectively reflects red / blue light, and a known dichroic prism 8 that selectively transmits green light again combines the light beams into one light beam and makes it enter the projection lens 9. The light flux that has passed through the projection lens 9 becomes projection light 101, which is magnified and formed as a projection image on the screen 10 for viewing.

FIG. 2 shows an illuminance distribution adjusting element 21 in FIG.
Is a transparent plate, and 23 is a minute dot paint. Further, FIG. 3 is a configuration diagram showing an example of the illuminance distribution adjusting element in FIG. 1 viewed macroscopically, so to speak, a dot in a region 24 corresponding to one pixel of the liquid crystal light valve 7 of the illuminance distribution adjusting element 21. Paint 2
3 shows a detailed configuration of No. 3.

First, the structure of the dot paint 23 will be described. As shown in FIG. 3, the region 24 corresponding to one pixel of the liquid crystal light valve 7 is divided into an N × N matrix (in the figure, divided into a 4 × 4 matrix) to obtain a desired transmittance in each pixel. As described above, black paint having an arbitrary shape and a certain size is selectively printed in each divided area. In the structure shown in FIG. 3A, a rectangular black paint is selectively printed in each divided area. In this configuration, when the number of dot paints in the region 24 corresponding to one pixel of the liquid crystal light valve is M, the transmittance T and the transmittance control interval Δ are: T [%] = {1−M / (N × N)} × 100 (1) Δ [%] = {1 / (N × N)} × 100 (2), and the transmittance T can be realized between 0 and 100 [%] (T = 75 in the figure). [%], Δ = 6.25 [%]). In the structure shown in FIG. 7B, circular black paint is selectively printed on each divided area. In this configuration, T [%] = {1−M / (N × N) × (π / 4)} × 100 (3) Δ [%] = {1 / (N × N) × (π / 4) } × 100 (4), the transmittance T = 0 [%] cannot be realized, but the control interval can be made slightly smaller than that in FIG. 9A (Δ = 4.9 [%] in the figure). . In the structure shown in FIG. 6C, the black paint is selectively printed on the outer side of the circle in each divided area, contrary to the structure shown in FIG. In this configuration, T [%] = {1−M / (N × N) × (1−π / 4)} × 100 (5) Δ [%] = {1 / (N × N) × (1− π / 4)} × 100 (6) and the minimum transmittance Tmin is as high as Tmin [%] = (π / 4) × 100 (7), but the control interval is small, so the transmittance is relatively lowered. It is effective when there is no need (Δ = 1.35 in the figure)
[%]). In the structure shown in FIG. 9D, a diamond-shaped black paint is selectively printed on each divided area. In this configuration, T [%] = {1−M / (N × N) × (1/2)} × 100 (8) Δ [%] = {1 / (N × N) × (1/2) } × 100 (9), and the minimum transmittance Tmin is Tmin [%] = 50 (10), which is lower than that in FIG. 7C, and the transmittance can be controlled at relatively small intervals. Therefore, it is effective when the matrix is small (Δ = 3.13 [%] in the figure).

Next, a method of making the illuminance distribution adjusting element 21 will be described. In the optical system shown in FIG. 12, R
The illuminance distribution on the screen of each of the (red), G (green), and B (blue) monochromatic light is measured in advance. As an example, it is assumed that the illuminance distribution at that time is as shown in FIG.
In FIG. 13, (R) is red light, (G) is green light,
(B) is the illuminance distribution of blue light, and the horizontal axis represents the relative image height Yr.
Is. The illuminance of the central portion of each monochromatic light is high, and the illuminance becomes lower toward the peripheral portion, but the illuminance distribution of each color is non-uniform. Therefore, R (red), G (green), B
(Blue) Illuminance distribution adjusting element 21 having a transmission characteristic as shown in FIG. 4 so that the ratio of the illuminance distribution of each monochromatic light becomes the same.
R, 21G, and 21B are created by printing the dot paint 23 on the transparent plates 22R, 22G, and 22B. Further, these dot dots may be formed on a transparent plate by a known vapor deposition method, or an opaque metal thin film formed on a transparent substrate by an etching method may be patterned in a dot shape. Alternatively, a thin metal plate may be formed by punching by an etching method.

FIG. 5 shows illuminance distribution adjusting elements 21R and 21R.
R (red), G (green), and B when G and 21B are inserted
(Blue) Illumination distribution on the screen 10 of each monochromatic light is shown. As compared with FIG. 13, it can be seen that the illuminance ratios of the red light, the green light, and the blue light at each relative image height Yr are equal. As described above, the color unevenness caused by the difference in the illuminance distribution ratio of each color on the screen 10 is well reduced over the entire projected image.

If necessary, a non-reflective coating (eg, R
For: 600-700 [nm], For G: 500-600 [nm],
For B: 400-500 [nm] wavelength band is transmitted). Thereby, the transmittance of the non-printed portion of the illuminance distribution adjusting element 21 can be slightly improved. Since the incident light and the transmitted light of the illuminance distribution adjusting element 21 are substantially parallel light, the incident angle dependency of the spectral transmission characteristic is not a big problem. Therefore, since the coating can be composed of a multilayer thin film, Fresnel reflection on the surface can be minimized.

In the present invention, the illuminance distribution adjusting element 21.
Is not only capable of controlling the light flux passing through each pixel by halftone printing using a monochromatic binarization process, but also does not require electrical correction, so it is inexpensive and produces less color unevenness and S /
It is possible to realize a projection display device having a good N. Further, by combining the color unevenness correction signal, which is an electric color unevenness correction means in the conventional projection display device, with the illuminance distribution adjusting element, a wider range of correction than the conventional color unevenness correction can be performed. The transmittance distribution of the illuminance distribution adjusting element 21 shown in FIG. 4 varies depending on the illuminance distribution of each color, but it goes without saying that this modification is a modification of the present invention.
Further, it goes without saying that the modification of the shape of the dot paint of the illuminance distribution adjusting element 21 shown in FIG. 3 is a modification of the present invention.

Example 2. FIG. 6 is a configuration diagram showing a projection type display device in Embodiment 2 of the present invention. In the figure, 3
Reference numeral 1 is a white balance adjusting element, 11 is an aperture, and the white balance adjusting element 31 is capable of continuously selecting from a transparent state (transparent plate) to an opaque plate state (diffusion plate) according to an applied voltage. It consists of a scattering mode light valve.

FIG. 7 is an operation explanatory view of a transmission / scattering mode light valve used as a white balance adjusting element in the second embodiment of the present invention. In the figure, 130,
Reference numeral 131 is a transparent substrate, and transparent conductive films 133 and 134 are formed on the inner surfaces facing each other. The liquid crystal 135 is dispersed in the polymer 136 matrix in the form of water droplets,
This is enclosed between the two transparent substrates 130 and 131. FIG. 7A shows the state when no voltage is applied.
Since 35 is oriented in an irregular direction, the polymer 13
6 and the liquid crystal 135 have different refractive indexes, and the incident light 121 becomes scattered light 123.

On the other hand, when a voltage equal to or higher than the threshold voltage Vth is applied by the power source 137, the orientation directions of the molecules of the liquid crystal 135 are aligned as shown in FIG. 7B. If the refractive index when the liquid crystal 135 is oriented in a certain direction is matched with the refractive index of the polymer 136 in advance, the incident light 121 becomes the transmitted light 122 without being scattered. The liquid crystal 135 increases with the applied voltage.
Since the degree of coincidence of the orientation directions of the is improved, the amount of light flux that is transmitted without being scattered is also increased.

Next, the operation of the above embodiment will be described. Similar to the first embodiment, of the light flux emitted from the lamp 1, the light flux reflected by the parabolic mirror 3 is substantially parallel illumination light 100.
Then, it enters the filter 4. The filter 4 transmits only visible light and reflects or absorbs unnecessary infrared / ultraviolet light. The illumination light 100 that has passed through the filter 4 enters the first dichroic mirror 5a. The dichroic mirror 5a reflects red light and transmits green / blue light. The red light 100R has its optical path bent by the reflection mirror 6a and is applied to the liquid crystal light valve 7R via the illuminance distribution adjusting element 21R and the white balance adjusting element 31R. The green light 100R and the blue light 100B that have passed through the first dichroic mirror 5a enter the second dichroic mirror 5b. The dichroic mirror 5b
Reflects green light and transmits blue light. Green light 100G
Is emitted to the liquid crystal light valve 7G through the illuminance distribution adjusting element 21G and the white balance adjusting element 31G. The blue light 100b transmitted through the second dichroic mirror 5b has its optical path bent by the two reflecting mirrors 6b and 6c, and is applied to the liquid crystal light valve 7B via the illuminance distribution adjusting element 21B and the white balance adjusting element 31B.

Light fluxes 100R, 100G, 10 modulated by the image formed on the liquid crystal light valves 7R, 7G, 7B.
Numeral 0B is combined into one light beam again by a known dichroic prism 8 which selectively reflects red / blue light and selectively transmits green light, and the projected light 1 is projected through a projection lens 9.
The number is 01, which is enlarged and formed as a projection image on the screen 10 for viewing.

Next, the principle of the optical system for removing the scattered light for obtaining the desired transmittance will be described. Figure 8 is transparent /
FIG. 3 is a principle diagram of an optical system for removing scattered light of a scattering mode light valve, in which 53 is a transmission / scattering mode light valve and 55 is a scattered light removing means. As shown in FIG. 8A, when the transmission / scattering mode light valve 53 is in the transmission mode, the incident light 51 does not scatter and becomes the transmitted light 52, and the entire luminous flux of the transmitted light 52 is the scattered light removing means 55. Can pass through the aperture.

When the transmission / scattering mode light valve 53 is in the scattering mode, the transmitted light 54 of the transmission / scattering mode light valve 53 is scattered as shown in FIG. 8B. The light flux that can be transmitted through the opening of the scattering removal means 55 is the light flux in the shaded portion of the scattered transmission light 54.

That is, the transmittance Tts of the transmission / scattering mode light valve 53 is determined by the scattered light removing means 5 in the transmission mode.
5 is determined by the ratio of the light flux 52 that passes through the aperture of No. 5 and the light flux in the shaded portion of the scattered transmitted light 54 that passes through the aperture of the scattered light removing means 55 in the scattering mode.

Assuming that the total luminous flux of the scattered transmitted light 54 when an arbitrary applied voltage is applied (arbitrary mode) is φs and the transmitted luminous flux in the transmission mode is φt, the luminous flux transmittance Ts in the arbitrary mode with respect to the transmission mode is Ts = φs / φt (11) Further, assuming that the luminous flux within the acceptance angle u of the scattered transmitted light 54 in an arbitrary mode is φu, the luminous flux transmittance Tu within the acceptance angle u of the scattered transmitted light 54 with respect to the luminous flux φt in the transmission mode is Tu = φu / φt = ( φu / φs) · Ts (12), which is the transmission / mode in the mode where an arbitrary applied voltage is applied.
The transmittance Tts of the scattering mode light valve 53 has the same value as Tu. FIG. 9 is a diagram showing the electro-optical characteristics of the white balance adjusting element according to the second embodiment of the present invention, showing the electro-optical characteristics of the transmission / scattering mode light valve 53. The vertical axis represents the transmittance T and the horizontal axis represents the applied voltage V.

The surface of the transparent substrate 130 on the incident side of the transmission / scattering mode light valve 53 is, if necessary, a non-reflective coating (eg, R: 600 to 700 [nm], G: 5).
00-600 [nm], B: 400-500 [nm] wavelength band is transmitted). Thereby, the transmittance of the transmission / scattering mode light valve 53 can be slightly improved. Since the light flux on the incident side of the transmission / scattering mode light valve 53 is substantially parallel light, the incident angle dependency of the spectral transmittance characteristic does not pose a problem. Therefore, since the coating can be composed of a multilayer thin film, Fresnel reflection on the surface can be minimized.

As described above, assuming that the diaphragm 11 in the projection lens 9 in FIG. 6 has the same function as the scattered light removing means 55, the light flux incident on the projection lens 9 is scattered within the acceptance angle of the diaphragm 11. The light is condensed on the diaphragm 11, and the light flux passing through the diaphragm 11 becomes the projection light 101,
The image is enlarged and projected on the screen 10. On the contrary, scattered light outside the acceptance angle of the diaphragm 11 is blocked by the diaphragm 11,
The screen 10 is not illuminated. That is, the diaphragm 11
Aperture diameter, the aperture 11 and the white balance adjusting element 31
The white balance adjusting element 31R according to the distance between
By applying an applied voltage to 31G and 31B, R ・ G
The ratio of the luminous fluxes illuminating the light valves corresponding to R, G, and B can be controlled by changing the overall transmittance of each of the B monochromatic lights.

Since the distance between the diaphragm 11 and the white balance adjusting element 31 is changed by providing a moving means (not shown) for shifting the position of the white balance adjusting element back and forth in the optical axis direction, the applied voltage is changed. It is possible to finely adjust the transmission characteristics even when the value is kept constant.

In the present invention, since the white balance adjusting element is composed of the transmission / scattering mode light valve, deterioration of the white balance adjusting element due to heat absorption is unlikely to occur when the transmittance is reduced. Can be used. Further, since there is no need to make electrical correction, it is possible to realize an inexpensive projection type display device capable of adjusting to a suitable white chromaticity with a good S / N. Further, by combining the white balance correction signal, which is the electrical white balance correction means in the conventional projection display device, and the white balance adjusting element, a wider range of correction than the conventional white balance correction can be performed. It should be noted that the arrangement of the white balance adjusting elements in all the optical paths of R, G, and B as described above is an example of the present invention, and even when the white balance adjusting element is arranged only in one or two optical paths, the present invention is It goes without saying that it does not defeat the purpose of the.

Example 3. FIG. 10 is a configuration diagram showing a projection type display device in Embodiment 3 of the present invention. In the figure,
41 is a chromaticity detector, 42 is an imaging lens, 43 is a color sensor, 44 is an arithmetic processing circuit, 45 is a white balance control circuit, and 102 is detection light.

Next, the operation of the above embodiment will be described. The chromaticity detector 41 is composed of an imaging lens 42, a color sensor 43, etc., and the color sensor 43 has a CI.
A spectral sensitivity correction filter (not shown) adjusted to have the spectral sensitivity of the spectral tristimulus value defined by E is built in. When white light is projected on the screen 10, the chromaticity detector 4 uses a part of the projected image as the detection light 102.
The light is received by 1, and the tristimulus value is calculated by performing photoelectric conversion or the like, and then the chromaticity is calculated from the tristimulus value through the arithmetic processing circuit 44 and output to the white balance control circuit 45.
A desired white chromaticity is stored in advance in the white balance control circuit 45 by a memory or the like.
The white balance is controlled by automatically adjusting the voltage applied to the white balance adjusting elements 31R, 31G, 31B from the white balance control circuit 45 via the signal line 46 so that the desired white chromaticity is obtained.

According to the present invention, a constant chromaticity of white light is automatically obtained automatically even if the emission spectrum of the lamp changes with time, and a projection display device having a good white balance can be realized.

Example 4. FIG. 11 is a configuration diagram showing a projection type display device in Embodiment 4 of the present invention. In the figure,
Reference numeral 47 is a switching mechanism for arranging the white balance adjusting element 31 in a position other than the optical path. By arranging the transmission / scattering mode light valve 53 which is the white balance adjusting element 31 in the optical path and applying a voltage of a predetermined value or more,
As shown in FIG. 11, the transmission / scattering mode light valve 5
The incident light 121 can be transmitted, but since the transmitted light flux is slightly reduced due to material absorption of the transmission / scattering mode light valve 53, the transmission when the transmission / scattering mode light valve is not arranged. The relationship φ> φt (13) always holds between the luminous flux φ and the transmitted luminous flux φt in the transmission mode. In order to solve this, for example, when it is not desired to reduce the transmitted light flux of the blue light 100B,
The white balance adjusting element 31B may be pulled out of the optical path by using the mechanism 47. In the embodiment shown in FIG. 11, the mechanism 47
The white balance adjusting element 31 is rotated around the rotation axis 48 of the light beam 100B to insert / remove the light flux 100B into / from the optical path.

In the present invention, even if the white balance adjusting elements are arranged in all the optical paths of R, G and B,
Since it can be arranged in a place other than the optical path by the switching mechanism, even if an arbitrary white balance adjusting element is unnecessary, it is possible to suppress an unnecessary reduction in transmittance due to the insertion of the white balance adjusting element. Can be realized. It should be noted that it is an example of the present invention that switching is performed so that the white balance adjusting element is not arranged only in the optical path of blue light as described above, and a switching mechanism is provided in other optical paths or in two or more optical paths. Needless to say, the provision of the above does not impair the gist of the present invention.

[0059]

Since the present invention is constructed as described above, it has the following effects.

The projection type display device according to the present invention is defined in claim 1.
According to this, by disposing the illuminance distribution adjusting element in at least one of the R, G, and B optical paths, it is possible to provide a projection display device with less color unevenness.

Further, according to the second aspect, since the illuminance distribution adjusting element can be formed by forming halftone dots smaller than the pixel size of the light valve to optically control the transmittance, the projection image can be produced at low cost. It is possible to effectively suppress the color unevenness.

Further, according to the third aspect, by disposing the illuminance distribution adjusting element outside the depth of field area of the projection lens, the halftone dots in the illuminance distribution adjusting element are connected to the image plane of the projected image. Since no image is formed, deterioration of image quality due to the halftone dots can be effectively suppressed.

Furthermore, according to the fourth aspect of the present invention, by providing the light incident surface and the light emitting surface of the illuminance distribution adjusting element with a non-reflection coating, the loss of the illumination luminous flux can be minimized even if the illuminance distribution adjusting element is arranged. Since this can be prevented as much as possible, it is possible to effectively realize high brightness of the projection light.

According to the fifth aspect, by disposing the white balance adjusting element in at least one optical path of R, G, and B, it is possible to provide a projection display device having a good white balance.

According to the sixth aspect, since the white balance adjusting element can be constituted by the transmission / scattering mode light valve, the transmission characteristic can be easily changed without deterioration of the element due to heat absorption.

Further, according to the seventh aspect, by applying a non-reflective coating on the light incident surface of the white balance adjusting element, even if the white balance adjusting element is arranged, the loss of the illumination luminous flux can be prevented to a minimum. Therefore, it is possible to effectively realize high brightness of the projection light.

Further, according to the eighth aspect, by finely adjusting the white balance of the projected image by shifting the white balance adjusting element back and forth in the optical axis direction.

According to a ninth aspect, the voltage applied to the transmission / scattering mode light valve is automatically changed by detecting the chromaticity of the projected light, and the white balance of the projected image is automatically adjusted. It is possible to provide a projection display device capable of performing the above.

According to the tenth aspect, since the white balance adjusting element can be arranged outside the optical path when the white balance adjusting element is unnecessary, the brightness of the projection light can be effectively increased. It is possible to provide a projection display device capable of performing the above.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an optical system of a projection display apparatus in Embodiment 1 of the present invention.

FIG. 2 is an external view of an illuminance distribution adjusting element in FIG.

FIG. 3 is a configuration diagram showing an example of the illuminance distribution adjusting element in FIG. 1 viewed macroscopically.

FIG. 4 is a diagram showing an example of transmission characteristics of an illuminance distribution adjusting element in Example 1 of the present invention.

FIG. 5 is a diagram showing an illuminance distribution of each of R, G, and B monochromatic lights in Example 1 of the present invention.

FIG. 6 is a configuration diagram showing a projection display device according to a second embodiment of the invention.

FIG. 7 is an operation explanatory diagram of a transmission / scattering mode light valve used as a white balance adjustment element according to a second embodiment of the present invention.

FIG. 8 is a diagram illustrating the principle of an optical system that removes scattered light from a transmission / scattering mode light valve.

FIG. 9 is a diagram showing electro-optical characteristics of a white balance adjustment element in Example 2 of the present invention.

FIG. 10 is a configuration diagram showing a projection display device according to a third embodiment of the invention.

FIG. 11 is a configuration diagram showing a projection type display device in Embodiment 4 of the present invention.

FIG. 12 is an explanatory diagram of an optical system of a projection type display device using a conventional liquid crystal light valve.

FIG. 13 is a diagram showing illuminance distributions of R, G, and B monochromatic lights in a conventional projection display device.

[Explanation of symbols]

 1 light source 2 lamp 3 reflecting mirror 4 filter 5 dichroic mirror 6 reflecting mirror 7 liquid crystal light valve 8 dichroic prism 9 projection lens 10 screen 11 aperture 21 illuminance distribution adjusting element 22 transparent plate 23 dot paint 31 white balance adjusting element 41 chromaticity detector 42 imaging lens 43 color sensor 44 arithmetic processing circuit 45 white balance control circuit 46 signal line 48 white balance adjusting element removing means 51 incident light 52 transmitted light 53 transmission / scattering mode light valve 54 scattered transmitted light 55 scattered light removing means 100 illumination light 101 projected light 102 detected light 121 incident light 122 transmitted light 123 scattered light 130, 131 transparent substrates 133, 134 transparent conductive film 135 liquid crystal 136 polymer 137 power supply 141 video signal correction circuit 142 signal Line

Claims (10)

[Claims] 1. A plurality of light valves for forming an image,
A projection lens for enlarging and projecting an image formed on the light valve, a light source means for emitting substantially parallel light for illuminating the light valve, and the substantially parallel light is decomposed into three primary color lights of red, green and blue. In a projection display device having an optical system including color separation means and color combination means for combining the primary color lights into one light after image formation, a central part and a peripheral part are provided in an optical path passing through the light valve. 2. A projection display device characterized in that an illuminance distribution adjusting element having different transmission characteristics is arranged in at least one optical path corresponding to the in-plane illuminance distribution of each light valve. 2. The projection display device according to claim 1, wherein the illuminance distribution adjusting element is formed by forming halftone dots smaller than a pixel size of the light valve. 3. The illuminance distribution adjusting element is arranged outside the depth of field region of the projection lens so that the halftone dots cannot be resolved on the image plane of the projected image. Projection display device. 4. The projection display device according to claim 1, wherein the light incident surface and the light emitting surface of the illuminance distribution adjusting element are non-reflection coated. 5. A plurality of light valves for forming an image,
A projection lens for enlarging and projecting an image formed on the light valve, a light source means for emitting substantially parallel light for illuminating the light valve, and the substantially parallel light is decomposed into three primary color lights of red, green and blue. In a projection display device having an optical system including color separation means and color combination means for combining the primary color lights into one light after image formation, red, green, and blue are provided in an optical path passing through the light valve. A white balance adjusting element capable of controlling the ratio of the luminous fluxes illuminating the light valves corresponding to the respective three primary colors is arranged in at least one optical path corresponding to the luminous flux amounts of the decomposed three primary color lights. A projection display device characterized by the above. 6. The white balance adjusting element is formed by a transmission / scattering mode light valve capable of continuously selecting from a transparent state to an opaque state according to an applied voltage. Projection display device. 7. The projection display device according to claim 5, wherein the light incident surface of the white balance adjusting element is non-reflection coated. 8. The projection display device according to claim 5, further comprising a moving unit that can shift the white balance adjusting element back and forth in the optical axis direction. 9. A plurality of light valves forming an image,
A projection lens for enlarging and projecting an image formed on the light valve, a light source means for emitting substantially parallel light for illuminating the light valve, and the substantially parallel light is decomposed into three primary color lights of red, green and blue. An optical system including a color separation unit and a color combination unit for combining the primary color lights into one light after image formation,
In the optical path that passes through the light valve, red, green, and blue 3
A white balance adjustment element that can control the ratio of the luminous flux that illuminates the light valve corresponding to each of the three primary colors.
At least 1 according to the luminous flux of the three primary color lights
In a projection display device arranged in one optical path, a chromaticity detection unit capable of detecting chromaticity of a projected image on the screen when white light is projected on the screen, and a chromaticity detection unit according to an output of the detection unit. And a circuit for controlling the white balance adjusting element. 10. A plurality of light valves for forming an image, a projection lens for enlarging and projecting an image formed on the light valve, a light source means for emitting substantially parallel light for illuminating the light valve, and the substantially parallel light source. Color separation means for separating light into three primary color lights of red, green, and blue, and the primary color light of 1 after the image formation.
An optical system including a color synthesizing unit for synthesizing two light beams is provided. A projection type display device having a controllable white balance adjusting element, comprising: a removing means capable of disposing the white balance adjusting element outside the optical path.