JP2003156711A - Projection display device - Google Patents

Abstract

(57) [Summary] (with correction) [PROBLEMS] A projection display having a function of efficiently cutting unnecessary reflected light to improve contrast without affecting display performance and having a function of arbitrarily adjusting contrast performance. Provide equipment. SOLUTION: A light source 1, a reflection type light valve 10,
An illumination optical system for condensing the light emitted from the light source 1 on a reflection type light valve 10, a projection lens 11 for enlarging and projecting the light on a screen, and substantially conjugate with an entrance pupil of the projection lens 11 in an optical path of the illumination optical system. And a shielding stop 31 capable of arbitrarily changing the size of the opening area at a desired position, wherein the shielding stop 31 is formed by two light-shielding portions, and the two light-shielding portions are provided by an illumination optical system. Are axially symmetrical in a predetermined direction with respect to the optical axis of the illumination optical system, and are movable so as to block light non-rotationally symmetrically with respect to the optical axis of the illumination optical system. Make the shape of the area to be shielded the same.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type display device for enlarging and projecting an optical image formed mainly on a light valve onto a screen.

[0002]

2. Description of the Related Art Conventionally, as a method for obtaining a large-screen image, an optical image corresponding to an image signal is formed on a light valve, the optical image is irradiated with light, and a projection lens is used to display the image on the screen. The method of magnifying and projecting is often used.
In such a method, by using a reflective light valve as the light valve, it is possible to achieve both high resolution and high pixel aperture ratio, and it is possible to display a high-luminance projection image with high light utilization efficiency. .

FIG. 9 shows an exemplary configuration of an optical system in a conventional projection display device using the reflection type light valve as described above. In FIG. 9, the illumination optical system that collects and illuminates the light emitted from the lamp 1 serving as a light source on the reflection type light valve 10 has a concave mirror 2 and a cross section having substantially the same aspect as the effective display surface of the reflection type light valve 10. It is composed of a square prism rod prism 4 having a ratio, a condenser lens 5, and a condenser mirror 6.

First, the concave mirror 2 has a reflecting surface having an elliptical cross section and has a first focal point and a second focal point. The center of the luminous body of the lamp 1 is arranged near the first focal point of the concave mirror 2, and the rod prism 4
Is arranged so that the light incident surface thereof is located near the second focal point of the concave mirror 2. The concave mirror 2 is formed by forming an optical multilayer film having a property of transmitting infrared light and reflecting visible light on the inner surface of a glass material.

Next, the light emitted from the lamp 1 is reflected and condensed by the concave mirror 2 to form a luminous body image of the lamp 1 at the second focal point of the concave mirror 2. The luminous body image of the lamp 1 is brightest near the center close to the optical axis, and tends to be darker toward the periphery, which causes a problem that unevenness in brightness remains. For such a problem, the second
The entrance surface of the rod prism 4 is arranged near the focal point, and the side surface of the rod prism 4 multiple-reflects the incident light to make the brightness uniform. By doing so, the emission surface of the rod prism 4 is used as a secondary surface light source, and an image is formed on the reflection type light valve 10 by the condenser lens 5 and the condenser lens 68 arranged thereafter, so that the illumination light It is possible to ensure uniformity.

The white light output from the lamp 1 is
Color wheel 3 arranged near the second focal point of concave mirror 2
Is time-divided into three primary colors of red, green and blue. The color wheel 3 is configured by combining three types of color filters that transmit only one of the three primary colors,
By rotating this, red, green, blue 3
Illuminate the primary color on the reflective light valve 10 in a time-sharing manner,
A full-color projection image can be displayed on one display element (reflection type light valve 10).

Next, the operation of the reflective light valve 10 will be described with reference to FIG. FIG. 10 is an operation explanatory diagram of a reflective light valve in a conventional projection display device.

In general, the reflection type light valve 10 controls the traveling direction of light according to a video signal and forms an optical image as a change in reflection angle. Mirror elements 21 are formed in a matrix for each pixel, and each mirror element 21 has an ON signal for white display and an OF signal for black display.
Each of the F signals is inclined by ± θ ° with respect to the plane 22 perpendicular to the optical axis of the projection lens. And the illumination chief ray 2
After passing through the cover glass 23, the light 4 enters and is reflected by the mirror element 21, and is emitted again from the cover glass 23.

Specifically, first, at the time of ON signal,
As shown in FIG. 10A, the incident angle of the illumination principal ray 24 is set so that the ON light principal ray 25 is reflected and travels in a direction perpendicular to the plane 22, that is, along the optical axis of the projection lens. In this case, the illumination chief ray 24 and the ON light chief ray 25
The angle formed by and is 2θ.

Further, when the OFF signal is given, the state shown in FIG.
As shown in (b), the OFF light principal ray 26 is reflected and travels in a direction in which it does not enter the projection lens, and the angle formed by the illumination principal ray 24 and the OFF light principal ray 26 is 6θ.

Therefore, as shown in FIG. 9, the illumination light 12 incident on the reflection type light valve 10 is incident on the projection lens 11 as ON light 13 when an ON signal is emitted, and as OFF light 14 when the OFF signal is emitted from the projection lens 11. It will proceed to the outside of the effective diameter. In this way, the ON light 13
By controlling the time distribution of the OFF light 14 and the OFF light 14 in accordance with the video signal, a projected image is formed on the screen.

[0012]

However, as shown in FIG.
Reflected light is always generated at the interface between the cover glass 23 and the air, which is the external medium, as shown in FIG.
In, the light travels as unnecessary reflected light 15 shown by the shaded area. Then, a part of the unnecessary reflected light 15 is turned ON / O.
Since the light enters the projection lens 11 at any FF signal, the quality of black display is significantly adversely affected particularly at the time of OFF signal, which causes a significant deterioration of the contrast performance. was there.

In order to solve the above problems, the present invention provides
An object of the present invention is to provide a projection display device having a function of efficiently cutting unnecessary reflected light to improve contrast without affecting display performance such as color reproducibility, and having a function of arbitrarily adjusting contrast performance. To do.

[0014]

In order to achieve the above object, a projection display apparatus according to the present invention comprises a light source, a reflection type light valve as image forming means, and a reflection type light valve for emitting light emitted from the light source. The illumination optical system that focuses the light on the screen, the projection lens that magnifies and projects the reflected light from the reflective light valve onto the screen, and the aperture area that is in the optical path of the illumination optical system and is approximately conjugate to the entrance pupil of the projection lens. And a shielding diaphragm whose size can be arbitrarily changed. The shielding diaphragm is formed by two light shielding portions, and the two light shielding portions are axially symmetric with respect to the optical axis of the illumination optical system in a predetermined direction. And
Further, it is characterized in that it can be moved so as to be non-rotationally symmetric with respect to the optical axis of the illumination optical system, and that the area of the area shielded by the two light shields and the shape of the area shielded are the same.

With this configuration, it is possible to improve the contrast performance while minimizing the decrease in brightness due to the generation of unnecessary reflected light and without degrading the color reproducibility.

In order to achieve the above object, the projection display device according to the present invention comprises a light source, a reflection type light valve as an image forming means, and light emitted from the light source is condensed on the reflection type light valve. The illumination optical system and the prism that reflects the illumination light from the illumination optical system to the reflective light valve side and transmits the reflected light from the reflective light valve and the reflected light from the reflective light valve are enlarged on the screen. A light-shielding unit having two projection-shielding lenses, and a shield diaphragm in the optical path of the illumination optical system, which is capable of arbitrarily changing the size of the aperture area at a position substantially conjugate with the entrance pupil of the projection lens, are provided. The two light shields are formed so as to be axially symmetric with respect to the optical axis of the illumination optical system in a predetermined direction, and are movable so as to shield in a non-rotationally symmetrical manner with respect to the optical axis of the illumination optical system. You can One of the shape of the area and area to be shielded areas to be shielded by the shielding portion and wherein the at least.

With this structure, it is possible to improve the contrast performance in a more compact structure while minimizing the decrease in brightness due to the generation of unnecessary reflected light and without deteriorating the color reproducibility. Becomes

In order to achieve the above object, the projection display device according to the present invention comprises a light source, three reflective light valves as image forming means, and radiated light from the light source on the reflective light valve. An illumination optical system that collects light, and a first prism that reflects the illumination light from the illumination optical system to the reflective light valve side and transmits the reflected light from the reflective light valve.
The illumination light is decomposed into three primary colors of red, blue, and green, and the second prism that combines the reflected light from the three reflective light valves and the reflected light from the reflective light valve are enlarged on the screen. A light-shielding unit having two projection-shielding lenses, and a shield diaphragm in the optical path of the illumination optical system, which is capable of arbitrarily changing the size of the aperture area at a position substantially conjugate with the entrance pupil of the projection lens, are provided. The two light shields are formed so as to be axially symmetric with respect to the optical axis of the illumination optical system in a predetermined direction, and are movable so as to shield in a non-rotationally symmetrical manner with respect to the optical axis of the illumination optical system. In addition, the area of the area shielded by the two light shields and the shape of the area shielded are the same.

With such a configuration, the contrast performance can be improved while minimizing the decrease in brightness due to the generation of unnecessary reflected light and without degrading the color reproducibility, and a high-definition full-color image can be obtained. It becomes possible to project and display.

Further, the projection display device according to the present invention is
The reflective light valve is preferably one in which a plurality of mirror elements for controlling the light reflection direction according to a video signal are arranged in a matrix.

Further, the projection display device according to the present invention is
It is preferable that the aperture shape of the shielding diaphragm is circular in the open state. Further, in the projection display device according to the present invention, it is preferable that the shape of the area shielded by the light shield is semicircular or crescent.

Further, the projection display device according to the present invention is
It is preferable that a reflecting mirror made of a metal or dielectric multilayer film that reflects at least 80% of incident light is formed on the surface of the light shielding portion of the shielding diaphragm. This is to prevent damage to peripheral devices due to radiant heat.

Further, the projection display device according to the present invention is
Illumination light from the illumination optical system is incident on the reflection type light valve from an oblique direction, and the light shielding part of the shielding diaphragm is illuminated from the position where the outer periphery of the illumination light and the outer periphery of the reflection light from the reflection type light valve are closest to each other. It is preferable to be movable so as to shield or open in the optical axis direction of the system.

Further, the projection display device according to the present invention is
It is preferable that the amount of light shielded by the shield diaphragm can be controlled from outside the device by remote control. This is because it is possible to arbitrarily control the balance between the contrast performance of the projected image and the light output performance.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION (First Embodiment) A projection display device according to a first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a first embodiment of the present invention.
It is a block diagram of the projection type display apparatus concerning. In FIG. 1, 1 is a lamp as a light source, 3 is a color wheel, 3
Reference numeral 1 is a diaphragm, 10 is a reflective light valve, and 11 is a projection lens. In the first embodiment, the optical system including the concave mirror 2, the rod prism 4, the condenser lens 5, and the condenser mirror 6 will be generically referred to as "illumination optical system" hereinafter.

In the reflection type light valve 10, as shown in FIG. 10, mirror elements 21 are formed in a matrix for each pixel, and the reflection angle is controlled by controlling the traveling direction of light according to a video signal. The optical image is formed in accordance with the change of.

The concave mirror 2 is composed of an ellipsoidal mirror whose reflecting surface has an elliptical cross section, and has a first focal point and a second focal point. Further, a xenon lamp is used as the lamp 1, the light-emitting body is arranged so that the center of the luminous body is located near the first focal point of the concave mirror 2, and the light incident surface of the rod prism 4 is the second mirror of the concave mirror 2. It is located near the focal point. The concave mirror 2
Is an optical multi-layer film having a property of transmitting infrared light and reflecting visible light on the inner surface of a glass material.

The rod prism 4 has a quadrangular prism shape whose light incident surface and light emitting surface have the same aspect ratio as that of the effective display surface of the reflection type light valve 10, and collects the light emitted from the lamp 1. Quartz glass, which is excellent in heat resistance, is preferable because it is placed in a place exposed to light. Then, in the vicinity of the incident surface of the rod prism 4, the luminous body image of the lamp 1 condensed by the concave mirror 2 is formed.

The luminous body image of the lamp 1 collected by the concave mirror 2 is brightest near the center close to the optical axis, and tends to darken rapidly toward the periphery. Therefore, non-uniformity of brightness remains in the surface. In contrast,
The bundle of rays incident on the rod prism 4 is multiply reflected by the side surface of the rod prism 4, and the illuminant images are subdivided and overlapped by the number of reflections to be illuminated. Therefore, the brightness is uniformized on the emission surface of the rod prism 4.

As described above, due to the effect of subdividing and superimposing the image of the lamp luminous body, the greater the number of reflections in the rod prism 4, the more the uniformity is improved. Therefore, the degree of uniformity depends on the length of the rod prism 4. Will depend on you. In the first embodiment, the rod prism 4 is adjusted so that the peripheral illuminance on the screen becomes 90% or more of the central illuminance.
Set the length of.

The exit surface of the rod prism 4 having uniform brightness is used as a secondary surface light source, and the effective display area of the reflection type light valve 10 is made by the condenser lens 5 and the condenser mirror 6 arranged thereafter. By forming an image with a magnification that matches with, it becomes possible to secure both the light collection efficiency and improve the uniformity.

The white light output from the lamp 1 is
Color wheel 3 arranged near the second focal point of concave mirror 2
By rotating, the three primary colors of red, green, and blue are sequentially illuminated on the reflective light valve 10 in a time-sharing manner, and one reflective light valve 10 can display a full-color projection image. .

The light emitted from the lamp 1 is condensed by the illumination optical system, and the illumination light 32 enters the reflection type light valve 10. Of the illumination light 32 that has entered the reflective light valve 10, the ON light 33 that corresponds to white display enters the projection lens 11 and is enlarged and projected on the screen (not shown). On the other hand, the OFF light 34 corresponding to black display is
Since the light travels outside the effective diameter of the projection lens 11,
You will not reach the screen.

The unnecessary reflected light 35 generated at the interface of the cover glass of the reflection type light valve 10 is made to be able to cut most of the area incident on the projection lens 11 by the diaphragm 31.

At this time, the light blocking area of the diaphragm 31 is preferably variable as shown in FIG. In FIG. 2, three examples of the diaphragm 31 having different shapes of the light shielding plate are shown in FIGS. 2 (a), 2 (b) and 2 (c), respectively.
In the first embodiment, a desired effect can be obtained with any configuration.

The diaphragm 31 arranged at a position substantially conjugate to the entrance pupil of the projection lens has a fixed diaphragm whose aperture diameter matches the F number specification of the entire system and whose position and aperture shape are fixed. 36 and light shields 37 and 38
Composed of a combination with.

For example, in the diaphragm 31 shown in FIG. 2A, at least two light shield plates 3 each having a straight line on one side.
By sliding 7a and 38a symmetrically,
Semi-circular light shielding portions 39a and 40a having the same area are formed.

Further, in the diaphragm 31 shown in FIG. 2B, two light shielding plates 37b and 38b having circular openings are provided.
Are symmetrically slid to form crescent-shaped light shielding portions 39b and 40b having the same area.

Further, the diaphragm 31 shown in FIG. 2 (c) is similar to FIG. 2 (b) in that two light-shielding plates having circular openings are used, but it is decentered from the center of the fixed diaphragm 36. Two light shields 37c and 38c having the same opening
However, by simultaneously changing the opening diameter by the same amount, crescent-shaped light shielding portions 39c and 40c having the same area are formed.

As described above, the light shielding plates 37a, 38a, 3
In the directions in which the areas of the light shielding portions 39a, 40a, 39b, 40b, 39c, and 40c formed by 7b, 38b, 37c, and 38c change, the illumination light 32 and the unnecessary reflected light 35 in FIG. It is one direction from the close direction to the optical axis direction of the illumination optical system, and the light shielding portion is set to shield or open in a non-rotationally symmetrical manner with respect to the optical axis of the illumination optical system.

Here, for example, the diaphragm 31 shown in FIG.
In this case, the effect of improving the contrast can be obtained even if the specification uses only one light shielding plate 37a. However, in that case, of the bundle of rays passing through the diaphragm,
The angle of the bundle of rays passing through the color wheel 3 shown in FIG. 2 is asymmetric with respect to the illumination optical axis. Since the red, green, and blue color filters that form the color wheel 3 have the characteristic that the spectral spectrum after transmission changes depending on the incident angle of the light beam, the chromaticity point of the projected image can also be changed by changing the light shielding plate 37a. The color reproducibility may change and the color reproducibility may be significantly deteriorated. In order to prevent this, it is necessary to use two light shielding plates 37a and 38a, and to change them so as to be axially symmetric with each other so that the area and shape of the light shielding portion are also axially symmetrical.

By using the diaphragm 31 having the shape of the light-shielding part as described above, the contrast performance can be improved without deteriorating the color reproducibility while minimizing the decrease in brightness due to the unnecessary reflected light 35 shown in FIG. Can be improved.

Further, in FIG. 1, the diaphragm 31 arranged in the optical path of the illumination optical system needs to be arranged at a position substantially conjugate with the pupil of the projection lens 11. If it is not arranged at such a position, a shadow may occur on a part of the projected image on the screen.

Further, it is desirable that the light shielding plates 37 and 38 shown in FIG. 2 have a surface reflectance of at least 80%. Since light with high energy enters the light-shielding part, if the amount of light absorbed on the surface of the light-shielding part becomes large, the temperature of the light-shielding part becomes higher as the light-shielding area becomes larger, and in some cases the radiant heat may damage surrounding optical components. Because there is also. In the first embodiment,
Although an aluminum plate whose surface is mirror-finished and has a reflectance of about 88% is used, other metal mirror-finished products such as stainless steel or a mirror element having a dielectric multilayer film formed on the surface of the substrate may be used.

FIG. 3 is a diagram showing the relationship between the amount of diaphragm light shielding and the projected image performance in the projection type display apparatus in which the variable diaphragm according to the first embodiment is introduced. FIG. 3 (a) is shown in FIG.
In the diaphragm 31 shown in (a), the light blocking plates 37a and 38
FIG. 3B shows the relationship between the light blocking amount of the diaphragm and the contrast ratio when a is slid symmetrically, when the light blocking plates 37a and 38a are slid symmetrically in the diaphragm 31 shown in FIG. 2A. The relationship between the diaphragm light shielding amount and the relative light output value is shown.

In FIGS. 3A and 3B, the horizontal axis represents the amount of light shielding when the light shielding plates 37a and 38a are slid per unit length in the arrow direction shown in FIG. 2A. There is. Therefore, the aperture light blocking amount increases toward the right.

Therefore, it can be seen from FIG. 3A that the contrast ratio of the projected image increases as the diaphragm light shielding amount increases, and from FIG. 3B, the light ratio increases as the diaphragm light shielding amount increases. It can be seen that the output decreases. From the above facts, the light blocking area of the diaphragm can be controlled from the outside of the set by remote control, and the balance between the contrast and the light output can be arbitrarily set as required.

By introducing such a function, it is possible to make the projected image with emphasis on the brightness according to the intended use.
Alternatively, it is possible to select a projection image with emphasis on contrast or to select it arbitrarily.

(Second Embodiment) Hereinafter, a projection display apparatus according to a second embodiment of the present invention will be described with reference to the drawings. FIG. 4 is a configuration diagram of a projection display apparatus according to the second embodiment of the present invention. In FIG. 4, the lamp 1 as a light source, the color wheel 3, the reflection type light valve 10, and the projection lens 11 are the same as those shown in FIG. In the second embodiment, the concave mirror 2, the rod prism 4, the condenser lens 5, the reflection mirror 42,
The optical system including the field lens 43 and the total reflection prism 44 will be generically referred to as "illumination optical system" hereinafter.

First, the concave mirror 2, the color wheel 3, the rod prism 4, and the condenser lens 5 are the same as those in the first embodiment. That is, the concave mirror 2 is composed of an ellipsoidal mirror whose reflection surface has an elliptical cross-sectional shape, and has a first focal point and a second focal point. Further, a xenon lamp is used as the lamp 1, and the light emitter is arranged so that the center of the light emitter is located near the first focal point of the concave mirror 2, and the light incident surface of the rod prism 4 is the second focal point of the concave mirror 2. It is arranged so that it is located in the vicinity. The concave mirror 2 is formed by forming an optical multilayer film having a property of transmitting infrared light and reflecting visible light on the inner surface of a glass material.

The rod prism 4 has a quadrangular prism shape having the same aspect ratio as the effective display surface of the reflection type light valve 10 on the light incident surface and the light emitting surface, and the radiated light from the lamp 1 is collected. Quartz glass, which is excellent in heat resistance, is preferable because it is placed in a place exposed to light. Then, the luminous body image of the lamp 1 condensed by the concave mirror 2 is formed in the vicinity of the incident surface of the rod prism 4.

The luminous body image of the lamp 1 collected by the concave mirror 2 is brightest near the center near the optical axis, and tends to darken rapidly toward the periphery. Therefore, non-uniformity of brightness remains in the surface. In contrast,
The bundle of rays incident on the rod prism 4 is multiply reflected by the side surface of the rod prism 4, and the brightness is uniformized on the exit surface of the rod prism 4. The greater the number of reflections within the rod prism 4, the higher the uniformity. Therefore, the degree of uniformity depends on the length of the rod prism 4. In the second embodiment, the length of the rod prism 4 is set so that the peripheral illuminance on the screen is 90% or more of the central illuminance.

The exit surface of the rod prism 4 having the uniform brightness is used as a secondary surface light source, and the effective display area of the reflection type light valve 10 is adjusted by the condenser lens 5 and the field lens 43 arranged thereafter. If images are formed at matching magnifications, it is possible to ensure both the efficiency of light collection and the improvement of uniformity.

The white light output from the lamp 1 is
Color wheel 3 arranged near the second focal point of concave mirror 2
By rotating, the three primary colors of red, green, and blue are sequentially illuminated on the reflective light valve 10 in a time-sharing manner, and one reflective light valve 10 can display a full-color projection image. .

In the configuration of the second embodiment, after the condenser lens 5 is emitted, it enters the total reflection prism 44 through the reflection mirror 42 and the field lens 43. Here, the operation of the total reflection prism 44 will be described below.

The total reflection prism 44 is composed of two prisms, and a very thin air layer 45 is formed on the adjacent surfaces of the prisms. When the illumination light 46 is incident on the air layer 45, the angle of the air layer 45 is set such that the illumination light 46 is incident at an angle equal to or greater than the critical angle, is totally reflected, and is incident on the reflective light valve 10 from an oblique direction. ON light 47
Is set so as to enter the air layer 45 at an angle equal to or less than the critical angle as a projection image, and to enter the projection lens 11 through the light. By thus providing the total reflection prism 44 in the optical path of the illumination optical system, the illumination optical system can be made compact.

Of the illumination light 46 incident on the reflection type light valve 10, the ON light 47 corresponding to white display is transmitted through the total reflection prism 44 and the projection lens 11 and enlarged and projected on the screen (not shown). . On the other hand, the OFF light 48 corresponding to black display does not reach the screen because it travels outside the effective diameter of the projection lens 11.

In the case of the second embodiment, in addition to the first unnecessary reflected light 49 generated at the cover glass interface of the reflection type light valve 10, the second unnecessary reflection light 49 generated at the interface of the total reflection prism 44 on the reflection type light valve 10 side. Any of the unnecessary reflected light 50 of 1 affects the contrast performance of the projected image. Also in this case, the degree of influence of the first unnecessary reflected light 49 and the second unnecessary reflected light 50 incident on the projection lens 11 can be arbitrarily changed by the diaphragm 41 that can change the area of the light shielding portion.

For example, as in the first embodiment, the aperture shape of the diaphragm 41 can be changed by using two light shielding plates that slide symmetrically as illustrated in FIG. The variable direction of the light shielding unit is the same as the illumination light 46 shown in FIG.
The unnecessary reflected light 49 is set so as to be blocked or opened in one direction from the closest direction to the optical axis direction of the illumination optical system.

Also in this case, by using two light shielding plates that are variable in axial symmetry, the incident angle of the bundle of light rays passing through the color wheel 3 is also axially symmetric, and projection is performed even if the shape or area of the light shielding portion changes. The chromaticity points of the image can be kept unchanged.

FIG. 5 shows a configuration diagram in the case where the diaphragm 41 is not arranged or the aperture of the diaphragm 41 is open in the configuration of FIG. In this case, the illumination light 51 is incident on the reflective light valve 10 and then becomes O corresponding to white display.
The N light 52 passes through the total reflection prism 44 and the projection lens 11 and is enlarged and projected on the screen (not shown). On the other hand, the OFF light 53 corresponding to black display does not reach the screen because it travels outside the effective diameter of the projection lens 11. Further, both the first unnecessary reflected light 54 and the second unnecessary reflected light 55 become factors that deteriorate the contrast performance of the projected image.

Therefore, by using the diaphragm 41 to block a part of the opening from the above-mentioned direction, the light flux of the first unnecessary reflected light 49 and the second unnecessary reflected light 50 shown in FIG. Is smaller than the light flux of the first unnecessary reflected light 54 and the second unnecessary reflected light 55 shown in FIG.

As described above, as shown in FIG. 4, both the first unnecessary reflected light 49 and the second unnecessary reflected light 50 can be efficiently cut by the diaphragm 41, and their areas are concentric circles. Compared to the case of a variable aperture, it is possible to improve the contrast performance while suppressing the decrease in brightness to the minimum and without degrading the color reproducibility.

Also in this case, the diaphragm 41 arranged in the optical path of the illumination optical system needs to be arranged at a position substantially conjugate with the pupil of the projection lens 7. Otherwise, a shadow may occur on a part of the projected image on the screen.

Further, it is desirable that the materials of the two light shield plates have a surface reflectance of at least 80%. Since light with high energy enters the light-shielding part, if the amount of light absorbed on the surface of the light-shielding part becomes large, the temperature of the light-shielding part becomes higher as the light-shielding area becomes larger, and in some cases the radiant heat may damage surrounding optical components. Because there is also. In the second embodiment, the surface is mirror-finished and an aluminum plate having a reflectance of about 88% is used. However, another metal mirror-finished product such as stainless steel or a dielectric multilayer film is formed on the surface of the substrate. A mirror element may be used.

Further, the light-shielding area of the diaphragm can be controlled from the outside of the set by remote control so that the contrast and the light output are balanced within the range of the contrast performance and the light output performance shown in FIG. It may be possible to set it arbitrarily. With such a configuration, it is possible to arbitrarily select a projection image that emphasizes brightness and a projection image that emphasizes contrast, depending on the intended use.

(Third Embodiment) A projection display apparatus according to a third embodiment of the present invention will be described below with reference to the drawings. FIG. 6 is a configuration diagram of a projection display apparatus according to the third embodiment of the present invention. 6, the lamp 1 as the light source, the reflection type light valve 10, and the projection lens 11 are the same as those shown in FIG. Further, as in FIG. 4, the system including the concave mirror 2, the rod prism 4, the condenser lens 5, the reflection mirror 42, the field lens 43, and the total reflection prism 44 is generically referred to as an “illumination optical system”. I will decide.

The configuration of such an illumination optical system is the same as that of the second embodiment.
Since it is the same as, the detailed description will be omitted.

The third embodiment is characterized in that a color separation / combination prism 62 is arranged between the total reflection prism 44 and the reflection type light valve 10, and three reflection type light valves 10 are used. . Here, the configuration and operation of the color separation / combination prism 62 will be described with reference to FIG. 7.

FIG. 7 shows the color separation / synthesis prism 6 shown in FIG.
2 is a horizontal sectional view of FIG. Color separation / synthesis prism 62
Is composed of three prisms, and a first dichroic mirror 71 and a second dichroic mirror 72 are formed on the adjacent surfaces of the respective prisms. In the case of the color separation / combination prism 62 according to the third embodiment,
The light 73 that has entered from the total reflection prism 44 is first reflected only by the first dichroic mirror 71 into blue light 74, and becomes blue light 74.
It is incident on B. Next, the second dichroic mirror 72
Then, only the red light is reflected by the red light 75 and enters the red reflective light valve 10R. And the first
The green light 76 transmitted through both the dichroic mirror 71 and the second dichroic mirror 72 is incident on the reflection type light valve 10G for green.

The three colors of light are reflected by the corresponding reflection type light valves 10B, 10R and 10G, and then combined again by the first dichroic mirror 71 and the second dichroic mirror 72 to form a total reflection prism. It is incident on 44. In this way, white light is converted into red, blue,
Three reflective light valves 10B, 10R, 10 corresponding to the respective video signals are decomposed and combined into the three primary colors of green.
By using G, it is possible to display a high-definition, full-color projection image.

The dichroic mirrors 71 and 72 also have the characteristic that the spectral spectrum after transmission changes depending on the incident angle of the light beam, as in the color wheel as described above.

Of the illumination light 63 incident on the reflection type light valve 10 shown in FIG. 6, ON light 64 corresponding to white display.
Is transmitted through the color separation / combination prism 62, the total reflection prism 44, and the projection lens 11 and on the screen (not shown).
Is enlarged and projected. On the other hand, the OFF light 6 corresponding to black display
No. 5 travels outside the effective diameter of the projection lens 11 and does not reach the screen.

In the case of the third embodiment, unnecessary reflected light generated at the interface of the cover glass of the reflection type light valve 10 in the first and second embodiments and at the interface of the total reflection prism 44 on the reflection type light valve 10 side are generated. In addition to the unnecessary reflected light (none of which is shown in FIG. 6), the unnecessary reflected light 66 generated at the interface of the color separation / combination prism 62 also affects the contrast performance of the projected image. Also in this case, the degree of influence of the unnecessary reflected light 66 entering the projection lens 11 can be arbitrarily changed by the diaphragm 61 whose area of the light shielding portion can be changed.

The aperture shape of the diaphragm 61 can be varied by using, for example, two light shielding plates that slide symmetrically as illustrated in FIG. The variable direction of the light shield is
The illumination light 63 and the first unnecessary reflected light 66 in FIG. 6 are set to be blocked or opened in one direction from the direction in which they are closest to each other toward the optical axis direction of the illumination optical system.

In this case, two light shielding plates that are axially symmetrically variable are used.
By using one of them, the incident angle of the light beam passing through the dichroic mirrors 71 and 72 of the color separation / combination prism 62 becomes axially symmetric, and the chromaticity point of the projected image does not change even if the shape or area of the light shielding part changes. Can be

FIG. 8 shows a configuration diagram in the case where the diaphragm 61 is not arranged or the aperture of the diaphragm 61 is open in the configuration of FIG. The illumination light 81 in this case is incident on the reflective light valve 10 and then turned on corresponding to white display.
The light 82 is the color separation / synthesis prism 62 and the total reflection prism 4.
4. The light passes through the projection lens 11 and is enlarged and projected on the screen (not shown). On the other hand, OFF corresponding to black display
The light 83 travels outside the effective diameter of the projection lens 11,
Does not reach the screen. In addition, the unnecessary reflected light 84
Causes deterioration of the contrast performance of the projected image. Although not shown, in this case as well, unnecessary reflected light generated at the interface of the cover glass of the reflective light valve 10 and unnecessary reflected light generated at the interface of the total reflection prism 44 are shown in FIG.
And the same effect as that shown in FIG.

Therefore, by blocking a part of the opening from the above-mentioned direction by using the diaphragm 61, the thickness of the ray bundle of the unnecessary reflected light 66 shown in FIG. 6 becomes the unnecessary reflected light 84 shown in FIG. It can be seen that it is thinner than the ray bundle of.

As described above, the unnecessary reflected light 66 of FIG.
It is possible to efficiently cut by the diaphragm 61, and it is possible to improve the contrast performance without deteriorating the color reproducibility while minimizing the decrease in brightness as compared with the case of the diaphragm in which the area is varied by concentric circles. it can.

Also in this case, the diaphragm 61 arranged in the optical path of the illumination optical system needs to be arranged at a position substantially conjugate with the pupil of the projection lens 11. Otherwise, a shadow may occur on a part of the projected image on the screen.

Further, it is desirable that the diaphragm light-shielding plate has a surface reflectance of at least 80%. Since light with high energy enters the light-shielding part, if the amount of light absorbed on the surface of the light-shielding part becomes large, the temperature of the light-shielding part becomes higher as the light-shielding area becomes larger, and in some cases the radiant heat may damage surrounding optical components. Because there is also. In the third embodiment, the surface is mirror-finished and an aluminum plate having a reflectance of about 88% is used. However, another metal mirror-finished product such as stainless steel or a dielectric multilayer film is formed on the surface of the substrate. A mirror element may be used.

Further, the light-shielding area of the diaphragm can be controlled from the outside of the set by remote control, and the contrast and the light output can be balanced as required within the range of the contrast performance and the light output performance shown in FIG. It may be possible to set it arbitrarily. With such a configuration, it is possible to arbitrarily select a projection image that emphasizes brightness and a projection image that emphasizes contrast according to the intended use.

In the first to third embodiments, the light shielding area of the diaphragm is variable so that the contrast performance and the light output can be adjusted arbitrarily. It is also possible to use a diaphragm with a fixed shape and area of the light-shielding portion and to use it only with desired contrast performance.

Further, although the diaphragm used in the first to third embodiments is arranged in the optical path of the illumination optical system which is substantially conjugate with the entrance pupil of the projection lens, it may be arranged directly in the entrance pupil of the projection lens. The effect of is obtained. However, if it is placed in the projection lens, it should be noted that the reflected light or heat generated by the light-shielding portion itself of the diaphragm may directly adversely affect the imaging performance of the projection lens and the quality of the projected image on the screen.

Further, in the diaphragm used in the first to third embodiments, an optical image is formed by controlling the traveling direction of light according to a video signal like the reflection type light valve shown in FIG. It has the greatest effect on light valves, but if it is a reflective light valve that has transparent glass or plastic on the exit side of the image forming surface, the polarization state of light using liquid crystal etc. as the modulation material. Even when using a light valve of a type that forms an optical image as a change in the diffraction state or the scattering state, it is possible to obtain the effect of reducing unnecessary reflected light.

[0086]

As described above, according to the projection type display device of the present invention, the projection type display device using the reflection type light valve for forming an image by controlling the traveling direction of light according to the video signal. In, it is possible to improve the contrast without impairing the color reproducibility. Further, by making the light blocking amount of the diaphragm variable, it becomes possible to arbitrarily control the balance between the contrast performance and the light output performance of the projected image.

[Brief description of drawings]

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

FIG. 2 is an explanatory diagram of a diaphragm shape in the projection display device according to the first exemplary embodiment of the present invention.

FIG. 3 is a diagram showing contrast and light output characteristics in the projection display apparatus according to the first embodiment of the present invention.

FIG. 4 is a configuration diagram of a projection display device according to a second embodiment of the present invention.

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

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

FIG. 7 is a configuration diagram of a color separation / combination prism in the projection display apparatus according to the third embodiment of the present invention.

FIG. 8 is a configuration diagram of a projection display device according to a third embodiment of the present invention.

FIG. 9 is a configuration diagram of a conventional projection display device.

FIG. 10 is an operation explanatory diagram of a reflective light valve in a conventional projection display device.

[Explanation of symbols]

1 Lamp 2 Concave Mirror 3 Color Wheel 4 Rod Prism 5 Condenser Lens 6 Condensing Mirror 10 Reflective Light Valve 11 Projection Lens 13, 33, 47, 52, 64, 82 ON Light 14, 34, 48, 53, 65, 83 OFF Light 21 Mirror elements 31, 41, 61 Stop 35, 49, 50, 54, 55, 66, 84 Unwanted reflected light 37, 38 Light shields 39, 40 Light shield 42 Reflection mirror 43 Field lens 44 Total reflection prism 45 Air layer 46 , 51, 63, 81 Illumination light 62 Color separation / synthesis prism 68 Condensing lenses 71, 72 Dichroic mirror

Claims (21)

[Claims] 1. A light source, a reflection type light valve as an image forming means, an illumination optical system for condensing emitted light of the light source on the reflection type light valve, and a reflection light from the reflection type light valve. A projection lens for magnifying and projecting on a screen; and a shield diaphragm in the optical path of the illumination optical system at a position substantially conjugate with the entrance pupil of the projection lens, the size of the aperture area being arbitrarily variable, The shield diaphragm is formed by two light shields,
The two light-shielding portions are axially symmetrical with respect to the optical axis of the illumination optical system in a predetermined direction, and are movable so as to be non-rotationally symmetrical with respect to the optical axis of the illumination optical system. A projection display device, wherein the area of the area shielded by the two light shields and the shape of the area shielded are the same. 2. The projection display device according to claim 2, wherein the reflection type light valve is formed by arranging a plurality of mirror elements for controlling a reflection direction of light according to a video signal in a matrix. 3. The projection display device according to claim 1, wherein an opening shape of the shielding diaphragm is circular in an open state. 4. The projection display device according to claim 1, wherein the shape of the region shielded by the light shield is semicircular or crescent. 5. The projection display according to claim 1, wherein a reflecting mirror made of a metal or dielectric multilayer film that reflects incident light by at least 80% or more is formed on a surface of the light shielding portion of the shielding diaphragm. apparatus. 6. Illumination light from the illumination optical system is incident on the reflection type light valve from an oblique direction, and the light shielding portion in the shielding diaphragm is configured such that the outer periphery of the illumination light and the reflection light from the reflection type light valve. The projection display device according to claim 1, wherein the projection display device is movable so as to shield or open in a direction of an optical axis of the illumination optical system from a position closest to the outer periphery of the projection display device. 7. The projection display device according to claim 1, wherein the amount of light shielded by the shield diaphragm can be controlled by remote control from outside the device. 8. A light source, a reflection type light valve as an image forming means, an illumination optical system for condensing emitted light of the light source onto the reflection type light valve, and an illumination light from the illumination optical system. A prism that reflects to the reflective light valve side and transmits the reflected light from the reflective light valve, a projection lens that magnifies and projects the reflected light from the reflective light valve onto a screen, and an optical path of the illumination optical system. A shielding diaphragm capable of arbitrarily changing the size of the opening area is provided at a position substantially conjugate with the entrance pupil of the projection lens, and the shielding diaphragm is formed by two light shielding portions, and The light-shielding portion is axially symmetric with respect to the optical axis of the illumination optical system in a predetermined direction, is movable so as to be non-rotationally symmetrical with respect to the optical axis of the illumination optical system, and further comprises the two Projection display device, wherein the shape of the area and area to be shielded areas to be shielded by the light unit is identical. 9. The projection display device according to claim 8, wherein the reflection type light valve is formed by arranging a plurality of mirror elements for controlling a reflection direction of light according to a video signal in a matrix. 10. The projection display device according to claim 8, wherein an opening shape of the shielding diaphragm is circular in an open state. 11. The projection display device according to claim 8, wherein the shape of the area shielded by the light shield is semicircular or crescent. 12. The projection display according to claim 8, wherein a reflection mirror made of a metal or dielectric multilayer film that reflects incident light by at least 80% or more is formed on a surface of the light shielding portion of the shielding diaphragm. apparatus. 13. Illumination light from the illumination optical system is incident on the reflection type light valve in an oblique direction, and the light shielding portion of the shielding diaphragm is provided with an outer periphery of the illumination light and reflection light from the reflection type light valve. 9. The projection display device according to claim 8, wherein the projection display device is movable so as to be shielded or opened in a direction of an optical axis of the illumination optical system from a position closest to the outer periphery of the. 14. The projection display device according to claim 9, wherein the amount of light shielded by the shield diaphragm can be controlled by remote control from outside the device. 15. A light source, three reflection type light valves as image forming means, an illumination optical system for condensing emitted light of the light source on the reflection type light valve, and illumination light from the illumination optical system. A first prism that reflects light to the reflective light valve side and transmits the reflected light from the reflective light valve; and the illumination light is decomposed into three primary color lights of red, blue, and green.
A second prism for combining one reflected light from the two reflective light valves; a projection lens for magnifying and projecting the reflected light from the reflective light valve onto a screen; and a projection lens in the optical path of the illumination optical system. A shield diaphragm that can arbitrarily change the size of the aperture area is provided at a position substantially conjugate to the entrance pupil of the projection lens, and the shield diaphragm is formed by two light shielding portions, and the two light shielding portions are They are axially symmetric with respect to the optical axis of the illumination optical system in a predetermined direction, and are movable so as to be non-rotationally symmetrical with respect to the optical axis of the illumination optical system, and are further shielded by the two light shielding portions. A projection display device characterized in that the area of the shielded area and the shape of the shielded area are the same. 16. The projection display device according to claim 15, wherein the reflection type light valve comprises a plurality of mirror elements arranged in a matrix for controlling a light reflection direction according to a video signal. 17. The projection display device according to claim 15, wherein an opening shape of the shielding diaphragm is circular in an open state. 18. The projection display device according to claim 15, wherein the shape of the region shielded by the light shield is semicircular or crescent. 19. The projection display according to claim 15, wherein a reflecting mirror made of a metal or dielectric multilayer film that reflects incident light by at least 80% or more is formed on the surface of the light shielding portion of the shielding diaphragm. apparatus. 20. Illumination light from the illumination optical system is incident on the reflection-type light valve from a direction, and the light-shielding portion of the shielding diaphragm is configured such that the outer periphery of the illumination light and the reflection light from the reflection-type light valve. 16. The projection display device according to claim 15, wherein the projection display device is movable so as to be shielded or opened in a direction of an optical axis of the illumination optical system from a position closest to the outer periphery of the. 21. The amount of light shielded by the shield diaphragm can be controlled by a remote control from outside the device.
The projection display device described.