JPH0727997A - Projection type display device - Google Patents

Abstract

PURPOSE:To provide a projection type display device which is bright and has neither irregular color nor uneven luminance. CONSTITUTION:Nearly parallel light beams emitted from a light source 84 are made incident on a liquid crystal panel 89. The panel 89 is arranged so that the center of its screen may be deviated with respect to the optical axis of a projection lens 90. The optical axis of the light source 84 is aligned with the main light beam of the lens 90 transmitted through the center of the screen of the panel 89. A diaphragm 91 and an inclined diaphragm 92 nearer a screen 93 side than the diaphragm 91 are arranged in the lens 90. The emitted light from the panel 89 is made incident on the lens 90 and enlarged and projected to the screen 93 after restricting luminous flux with the diaphragms 97 and 92. By using the inclined diaphragm, the uneven luminance on the screen 93 is improved.

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 which illuminates an image formed on a light valve with illumination light and projects it on a screen by a projection lens.

[0002]

2. Description of the Related Art A method for illuminating an image formed on a small light valve according to a video signal with illumination light and enlarging and projecting the optical image on a screen by a projection lens in order to obtain a large-screen image. Is better known than before. In recent years, a projection type display device using a liquid crystal panel as a light valve has been receiving attention (for example, Japanese Patent Laid-Open No. 25001/1990).
No. 5, etc.).

FIG. 8 shows an example of the configuration of a conventional projection display device using one projection lens.

The light source 4 includes a lamp 1, a concave mirror 2 and a filter 3.
Composed of. The light emitted from the lamp 1 is converted into almost parallel light by the concave mirror 2, and infrared light is emitted by the filter 3.
The ultraviolet rays are removed, and the liquid crystal panel 6 is passed through the plano-convex lens 5.
Incident on. The liquid crystal panel 6 is arranged with its screen center displaced from the optical axis of the projection lens 7 in order to obtain the best contrast. An image corresponding to a video signal is formed on the liquid crystal panel 6, and the light transmitted through the liquid crystal panel 6 is enlarged and projected on the screen 8 by the projection lens 7.

FIG. 9 shows an example of the configuration of a conventional projection display device using three projection lenses.

The light source 14 comprises a lamp 11, a concave mirror 12 and a filter 13. The white light radiated from the lamp 11 is converted into parallel light by the concave mirror 12, the infrared rays and the ultraviolet rays are removed by the filter 13, and the white light is incident on the color separation optical system 18. The color separation optical system 18 includes three dichroic mirrors 1 for blue reflection, green reflection, and red reflection, respectively.
The light emitted from the light source 14 is separated into blue, green, and red primary color lights. After passing through the field lenses 19, 20, and 21, the primary color lights respectively enter the liquid crystal panels 22, 23, and 24. LCD panel 2
An image corresponding to a video signal is formed on 2, 23, 24, and blue transmitted through the liquid crystal panels 22, 23, 24,
Each of the green and red primary color lights has three projection lenses 25,
The images are enlarged and projected by 26 and 27, and are combined on the screen 28 into a color image.

In the arrangements shown in FIGS. 8 and 9, the color synthesizing optical system is unnecessary, so that the distance between the liquid crystal panel and the projection lens can be shortened. Since the projection lens has no restriction on the back focus, the distance from the projection lens to the center of the screen can be shortened, and a compact projection display device can be configured.

[0008]

When the illuminance E of the projected image on the screen is E ₀ when the illuminance at the center of the projected image on the optical axis of the projection lens is E ₀ ,

[0009]

[Equation 1]

It is represented by Here, K is the aperture efficiency of the projection lens, and ω is the angle of view of the projection lens. The illuminance E on the screen is proportional to the product of the aperture efficiency K of the projection lens and cos ⁴ ω.

In the configuration shown in FIG. 8, the liquid crystal panel 6
Since the center of the screen is arranged so as to be displaced from the optical axis of the projection lens 7, the center of the projected image does not coincide with the optical axis of the projection lens 7, and the projection is oblique. Therefore, there is a problem in that the angle of view of the projection lens 7 with respect to both ends of the projected image is different and uneven brightness occurs in the projected image.

Further, in the configuration shown in FIG. 9, the positions of the optical axes of the three projection lenses 25, 26 and 27 are different, so that blue, green and red are displayed at arbitrary points on the screen 28. The angle of view of each projection lens 25, 26, 27 is different,
The illuminance distributions of the blue, green, and red projected images are different.
(FIG. 10) shows the illuminance distributions of blue, green, and red projection images by cos ⁴ ω of the projection lens. As is clear from the figure, color unevenness occurs in the composite image of the blue, green, and red projection images.

In order to improve such unevenness in brightness and color of the projected image, a method of correcting the input video signal to the liquid crystal panel by brightness modulation or a light quantity attenuation filter for correcting the quantity of light incident on each panel is corrected. There is a way to do it. However, both methods reduce the illuminance at other positions with respect to the position where the illuminance is the lowest on the screen, resulting in uneven brightness.
This is a method of improving color unevenness, and thus there is a problem that the brightness of the projected image is reduced.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a projection-type display device with bright color unevenness and less brightness unevenness.

[0015]

In order to achieve this object, a projection display device of the present invention is provided with a light source and a light valve in which an optical image corresponding to a video signal is formed by receiving light emitted from the light source. And a projection lens for receiving the light emitted from the light valve and projecting the optical image on a screen, the light valve is arranged with its screen center offset from the optical axis of the projection lens, and the projection lens is It is provided with a diaphragm tilted with respect to the optical axis.

Further, the projection display device of the present invention comprises a light source, a color separation means for separating the white light emitted from the light source into light of blue, green and red color components, and the color separation means. Three light valves that receive the emitted light and form an optical image corresponding to a video signal, and three projection lenses that respectively receive the emitted light from the light valves and project the optical images on a screen are provided. The two light valves of the three light valves are arranged with their screen centers displaced from the optical axis of the corresponding projection lens, and the two corresponding projection lenses are inclined with respect to the optical axis. It is equipped with a diaphragm.

Further, the projection display device of the present invention includes a light source, a color separation means for separating white light emitted from the light source into light of blue, green and red color components, and the color separation means. Three light valves that receive the emitted light and form an optical image corresponding to a video signal; and a color synthesizing unit that receives the emitted light from each of the light valves and synthesizes light of blue, green, and red color components, A projection lens for receiving light from the color synthesizing means and projecting the light onto a screen, wherein each of the light valves is arranged with its screen center displaced from the optical axis of the projection lens,
The projection lens includes a diaphragm inclined with respect to the optical axis of the projection lens.

[0018]

According to the present invention, the projection lens corresponding to the light valve arranged so that the center of the screen is displaced from the optical axis of the projection lens is provided with the diaphragm inclined with respect to the optical axis of the projection lens. It is possible to control the illuminance distribution on the screen of the projected image obtained by 1). Hereinafter, the tilted diaphragm provided in the projection lens will be referred to as a tilt diaphragm. The slanted diaphragm is, for any point on the screen,
The luminous efficiency can be reduced by lowering the aperture efficiency at the point where the angle of view of the projection lens becomes small. Further, it is possible to increase the aperture efficiency at the point where the angle of view of the projection lens becomes large and increase the luminous flux.

When performing oblique projection with one projection lens,
By arranging a tilt diaphragm on the projection lens and adjusting the size and tilt angle of the aperture, uneven brightness caused by different angles of view of the projection lens with respect to both ends of the projected image is improved.

When the blue, green, and red projection images are combined on the screen by using the three projection lenses, the aperture efficiency is controlled according to the angle of view of the three projection lenses, and the three projection lenses are projected. The illuminance distribution of the projected image of the lens can be made the same,
Color unevenness of the composite projected image is improved.

[0021]

Embodiments of the projection display apparatus of the present invention will be described below with reference to the drawings.

FIG. 1 shows the structure of the projection type display device in the first embodiment of the present invention. 34 is a light source, 38 is a color separation optical system, 45, 46 and 47 are liquid crystal panels, 48, 49 and 50 are projection lenses, and 55 is a screen.

The light source 34 comprises a lamp 31, a concave mirror 32, and a filter 33. As the lamp 31, a metal halide lamp is used. The color separation optical system 38 includes dichroic mirrors 35, 3 for blue reflection, green reflection, and red reflection, respectively.
It is composed of 6,37. Liquid crystal panels 45, 46, 47
Is composed of a twist nematic mode liquid crystal cell 43 and polarizing plates 42 and 44. Projection lens 48, 49, 50
Are arranged in the horizontal direction of the screen of the liquid crystal panels 45, 46, 47 with their optical axes parallel to each other. Center projection lens 49
Is arranged such that its optical axis is perpendicular to the center of the screen 55, and diaphragms 51 and 53 are arranged. The projection lenses 48 and 50 at both ends are provided with a diaphragm 51 and inclined diaphragms 52 and 54 on the screen 55 side of the diaphragm 51, respectively.

The light emitted from the lamp 31 is the concave mirror 3
After being converted into light that is nearly parallel by 2, the light enters the filter 33. The filter 33 is for removing infrared rays and ultraviolet rays. The light emitted from the filter 33 is reflected by the dichroic mirror 35 as blue component light, and transmits light containing green and red components. The light including the green and red components transmitted through the dichroic mirror 35 is reflected by the dichroic mirror 36 as the green component light, and the light including the red component is transmitted. With respect to the light including the red component that has passed through the dichroic mirror 36, the red component light is reflected by the dichroic mirror 37 and the unnecessary component light is transmitted.

In this way, of the respective color lights separated by the color separation optical system 38, the blue component light is transmitted to the field lens 39,
The green component light enters the field lens 40, and the red component light enters the field lens 41. Field lens 3
Reference numerals 9, 40 and 41 are for causing the light transmitted through the peripheral portions of the liquid crystal panels 45, 46 and 47 to enter the projection lenses 48, 49 and 50. Field lens 39, 40, 4
The light emitted from the light source 1 enters three transmissive liquid crystal panels 45, 46 and 47 arranged on the same plane. The liquid crystal panels 45, 46, 47 are of active matrix type,
An optical image is formed as a change in transmittance according to a video signal. Light emitted from the liquid crystal panels 45, 46, 47 enters the projection lenses 48, 49, 50. Projection lens 48,
The light rays entering 49 and 50 are limited in luminous flux by the diaphragms 51 and 53 and the tilt diaphragms 52 and 54, and are enlarged and projected on the screen 55. The blue, green, and red projection images are combined on the screen 55.

Now, let the horizontal direction of the screen of the liquid crystal panel 46 be x.
Consider an xyz orthogonal coordinate system in which the axis is the y-axis in the screen vertical direction and the optical axis of the projection lens 49 is the z-axis. In order to combine the images of the respective colored lights on the screen 55, the three liquid crystal panels 4
Two liquid crystal panels 4 other than the center among 5, 46, 47
Reference numerals 5 and 47 are arranged so that the screen center is shifted in the x-axis direction with respect to the optical axis of the corresponding projection lens. Further, by finely adjusting the position and inclination of the liquid crystal panels 45 and 47 on the plane,
Blue, green, and red projection images are superimposed on the screen 55.

FIG. 2 shows an optical path diagram of the projection lens 48. An inclined diaphragm 52 is arranged closer to the screen 55 than the diaphragm 51. Since the liquid crystal panel 45 is arranged with its screen center displaced from the optical axis of the projection lens 48 as shown in the figure, the projection lens 4 for the light emitted from the point P
The angle of view ω _{P of} 8 is larger than the angle of view ω _Q of the projection lens 48 with respect to the light emitted from the point Q. Therefore, from (Equation 1), the illuminance on the screen 55 with respect to the point P is
Is lower than the illuminance on the screen 55 with respect to. Therefore, the aperture efficiencies K _P and K _Q of the projection lens 48 at the points P and _Q are

[0028]

[Equation 2]

The size of the aperture and the tilt angle of the tilt diaphragm 52 are determined so as to satisfy the above condition. When the liquid crystal panel 45 is displaced in the x-axis direction as shown in the figure, the tilt diaphragm 52 is rotated about the y-axis and tilted. Similarly, for the projection lens 50, the size of the aperture of the tilt diaphragm 54 and the tilt angle are determined. However, from the light source 34 to the projection lens 48,
In the optical system up to 49, 50, the projection lenses 48, 4
The F number of the projection lenses 48, 49 and 50 is an inclined diaphragm with respect to the effective F number in which the size of the image of the light source 34 formed on the pupils of 9, 50 and the pupil diameter of the projection lenses 48, 49 and 50 match. It is necessary to reduce the size according to the inclination angles of 52 and 54.

In FIG. 2, the solid line indicates the projection lens 48.
The light fluxes passing through the points P and Q in the case where the tilted diaphragm 52 is arranged at are shown by dashed lines, and the broken lines show the light fluxes when the diaphragm 53 not tilted is arranged. As described above, by tilting the diaphragm, the light flux increases with respect to the point P where the angle of view ω of the projection lens 48 increases, and the point Q with which the angle of view decreases.
To reduce the luminous flux. In this way, by using the inclined diaphragms 52 and 54 for the projection lenses 48 and 50 and controlling the aperture efficiency according to the difference in the angle of view, color unevenness that occurs in the composite projection image of the projection lenses 48, 49 and 50. Can be improved.

Focus adjustment of the projection lenses 48, 49 and 50 is performed by moving the projection lenses 48, 49 and 50 along the z axis. At this time, the projection lenses 48 and 50 in which the tilt diaphragms 52 and 54 are arranged need to move so as not to rotate so that the tilt directions of the tilt diaphragms 52 and 54 do not change. Convergence adjustment of the composite projected image is performed by adjusting the focus of the green projected image with high visibility and adjusting the red and blue projected images to the green projected image. Projection lens 4
If the chromatic aberrations of 8, 49 and 50 are sufficiently corrected, the level will be practically acceptable. In addition, the projection lenses 48, 4
The distortion aberrations of 9,50 are practically no problem when an aspherical lens is used.

FIG. 3 shows the relative illuminance distribution on the screen 55 when the illuminances of the red and blue projected images are normalized by the illuminance of the green projected image. Three projection lenses 48, 49, 5
Since 0 is arranged in the x-axis direction, the distribution in the horizontal direction on the screen 55 is shown. The solid line is the projection lens 48,
50 is a case where the tilt diaphragms 52 and 54 are arranged, and the wavy line is a characteristic when the tilt diaphragms 52 and 54 are not provided. It can be seen that when the tilt diaphragms 52 and 54 are not provided, the illuminance of the blue component is high in the left part of the screen and the illuminance of the red component is high in the right part of the screen, resulting in color unevenness. However, the tilt diaphragms 52, 5
By disposing No. 4, the illuminance distributions of the blue, green and red components can be equalized without reducing the brightness, and the color unevenness can be improved.

In FIG. 2, the tilt diaphragm 52 is arranged on the screen 55 side of the diaphragm 51, but the same effect can be obtained by arranging the tilt diaphragm 52 on the liquid crystal panel 45 side of the diaphragm 51.

In order to correct the difference in the illuminance distribution of the projected image, the tilt diaphragms may be arranged at two positions when the correction is insufficient at one tilt diaphragm. FIG. 4 shows a projection lens 61 having tilt diaphragms arranged at two positions. By disposing the inclined diaphragm 62 also on the liquid crystal panel 45 side of the diaphragm 51, the illuminance distributions of the blue, green, and red components can be further equalized, and the color unevenness can be greatly improved.

When performing oblique projection, the central liquid crystal panel 4
If the screen center of 6 is displaced in the y-axis direction with respect to the optical axis of the projection lens 49, the angle of view of the projection lens 49 with respect to the top and bottom of the projected image is different, and thus uneven brightness occurs at the top and bottom of the screen. However, the uneven brightness can be improved by disposing an inclined diaphragm on the projection lens 49 and adjusting the size of the aperture and the inclination angle. In this case, the liquid crystal panels 45 and 47 at both ends
Is arranged such that its screen center is shifted in two directions of the x-axis and the y-axis with respect to the optical axes of the projection lenses 48 and 50, respectively. The color unevenness that occurs in the composite projected image can be improved by adjusting the size and the tilt angle of the openings of the tilt diaphragms 52 and 54 arranged on the projection lenses 48 and 50 at both ends, respectively.

FIG. 5 shows an optical path diagram when the projection lens 49 is provided with a tilt diaphragm 71 having a variable tilt angle and rotatable about the z axis. In the case of oblique projection, in order to project at an arbitrary projection angle, the projection lens 49 of the liquid crystal panel 46 is used.
It suffices to change the shift amount of the optical axis with respect to the optical axis. But,
When the projection angle changes, the angle of view of the projection lens 49 also changes, causing uneven brightness. In this case, the brightness uniformity of the projected image is adjusted by adjusting the tilt angle of the tilt diaphragm 71 as shown in the figure. Further, in order to project the projected image in an arbitrary direction, the liquid crystal panel 46 may be displaced in two directions of the x axis and the y axis with respect to the optical axis of the projection lens 49. However, when the projection direction changes, the angle of view of the projection lens 49 also changes, causing uneven brightness. In this case, the brightness uniformity of the projected image is adjusted by adjusting the tilt angle and the rotation angle of the tilt diaphragm 71. Similarly, the projection lenses 48 and 50 are also provided with the tilt diaphragms 71, and the tilt angle and the rotation angle thereof are adjusted according to the projection direction to improve the color unevenness of the composite projection image projected in any direction. You can

Although FIG. 1 shows the case where the liquid crystal panels 45 and 47 shift their screen centers in the x-axis direction with respect to the optical axes of the projection lenses 48 and 50, the projection lenses 48, 49, and
When 50 is arranged in the vertical direction of the screen, the screen center is set to y.
It will be shifted in the axial direction. In that case, since color unevenness occurs in the vertical direction of the screen 55, the tilt diaphragms 52, 54
Can be rotated about the x-axis and tilted.
By adjusting the size and the inclination angle of the openings 2, 54, it is possible to improve the color unevenness of the projected image.

FIG. 6 shows the configuration of the projection type display device in the second embodiment of the present invention. Reference numeral 84 is a light source, 89 is a liquid crystal panel, 90 is a projection lens, and 93 is a screen.

The light source 84 comprises a lamp 81, a concave mirror 82 and a filter 83. A halogen lamp is used as the lamp 81. The liquid crystal panel 89 is composed of a twisted nematic mode liquid crystal cell 87 having a mosaic color filter built therein and polarizing plates 86 and 88. Projection lens 90
A diaphragm 91 and an inclined diaphragm 92 are arranged inside the diaphragm 91. The screen 93 is arranged perpendicular to the optical axis of the projection lens 90.

The light emitted from the lamp 81 is reflected by the concave mirror 8.
The light is converted into light that is nearly parallel by 2 and enters the filter 83. The filter 83 is for removing infrared rays. The light transmitted through the filter 83 is the field lens 8
It is incident on 5. The light emitted from the field lens 85 enters the liquid crystal panel 89. The liquid crystal panel 89 is arranged with its screen center displaced from the optical axis of the projection lens 90. On the liquid crystal panel 89, an optical image corresponding to the video signal is formed. The light emitted from the liquid crystal panel 89 enters the projection lens 90. The light incident on the projection lens 90 has its luminous flux limited by the diaphragm 91 and the tilt diaphragm 92, and is enlarged and projected on the screen 93.

Now, let x be the horizontal direction of the screen of the liquid crystal panel 89.
Consider an xyz orthogonal coordinate system in which the y axis is the axis, the screen vertical direction is the y axis, and the optical axis of the projection lens 90 is the z axis. It is known that the best contrast ratio can be achieved when the incident angle of light rays on the liquid crystal panel 89 is inclined by several degrees. Therefore, the liquid crystal panel 89 is arranged so that the screen center is displaced in the y-axis direction with respect to the optical axis of the projection lens 90. The optical axis of the light source 84 is
It is matched with the chief ray of the projection lens 90 that passes through the center of the screen of the liquid crystal panel 89.

The projection lens 9 is provided at the center of the screen of the liquid crystal panel 89.
When 0 of the optical axis is arranged offset in the y-axis direction, since the angle of the projection lens 90 omega differs between the top of the screen and the lower screen of the projected image, projected by terms of cos ⁴ omega (Equation 1) Uneven brightness occurs at the top and bottom of the screen. In order to improve the brightness unevenness at the top and bottom of the screen, the aperture efficiency is controlled according to the difference in the angle of view of the projection lens 90 with respect to the top and bottom of the screen. The aperture efficiency can be controlled by adjusting the size of the aperture of the tilt diaphragm 92 and the tilt angle. in this case,
Since the brightness unevenness occurs in the vertical direction of the screen 93, the tilt diaphragm 92 is tilted by rotating around the x axis. The tilt diaphragm 92 acts to increase the aperture efficiency for the upper portion of the screen where the angle of view ω of the projection lens 90 is large, and to reduce the aperture efficiency for the lower portion of the screen where the angle of view is small, and The uneven brightness can be improved.

The liquid crystal panel 89 is also capable of shifting the screen center in the x-axis direction with respect to the optical axis of the projection lens 90.
Brightness unevenness occurs in the projected image. In this case, since the brightness unevenness occurs in the horizontal direction of the screen 93, the tilt diaphragm 92 may be rotated around the y axis and tilted.
By adjusting the size of the aperture and the tilt angle, it is possible to improve the brightness unevenness of the projected image.

Similar to the first embodiment, the tilt diaphragm 92 is
You may arrange | position on the liquid crystal panel 89 side of the diaphragm 91. Also,
The tilt diaphragm may be arranged on the screen 93 side and the liquid crystal panel 89 side of the diaphragm 91. Further, the projection lens 90 has a variable tilt angle, and the tilt diaphragm 71 is rotatable about the z axis.
By arranging, it is possible to improve the brightness unevenness that occurs in the projected image when the image is projected in an arbitrary direction according to the amount of shift of the screen center of the liquid crystal panel 89 with respect to the projection lens 90.

When the screen 93 is arranged so as to be inclined with respect to the optical axis of the projection lens 90, the projection image causes trapezoidal distortion as well as uneven brightness. In this case, the uneven brightness can be improved by the tilt diaphragm 71. The trapezoidal distortion may be corrected by changing the shape of the image using an image memory.

FIG. 7 shows the configuration of the projection type display device in the third embodiment of the present invention. Reference numeral 104 is a light source, 107 is a color separation optical system, 112, 113 and 114 are liquid crystal panels, 118 is a color combining optical system, 119 is a projection lens, and 122 is a screen.

The light source 104 is a lamp 101 and a concave mirror 10.
2 and the filter 103. As the lamp 101, a xenon lamp is used. The color separation optical system 107 includes red and green dichroic mirrors 105 and 1 respectively.
It is composed of 06. The color synthesizing optical system 118 includes dichroic mirrors 116 and 117 for green reflection and blue reflection, respectively. In the projection lens 119, a diaphragm 120 and
The tilt diaphragm 121 is arranged on the screen 122 side. The screen 122 is arranged perpendicular to the optical axis of the projection lens 119.

The near-parallel light from which the infrared rays and the ultraviolet rays are removed from the light source 104 is reflected by the dichroic mirror 105 as red component light, and the light containing green and blue components is transmitted. The light including the green and blue components that has passed through the dichroic mirror 105 is reflected by the dichroic mirror 106 as green component light and transmits as blue component light. The color lights separated by the color separation optical system 107 in this way enter the field lenses 109, 110, and 111, respectively. Light emitted from the field lenses 109, 110, and 111 enters three transmissive liquid crystal panels 112, 113, and 114. The liquid crystal panels 112, 113 and 114 are arranged with their screen centers displaced from the optical axis of the projection lens 119. On the liquid crystal panels 112, 113, 114, an optical image corresponding to the video signal is formed. The dichroic mirror 116 transmits the red component light from the liquid crystal panel 112 and reflects the green component light from the liquid crystal panel 113. The dichroic mirror 117 transmits red and green component light and reflects blue component light from the liquid crystal panel 114. In this way, the light combined by the color combining optical system 118 enters the projection lens 119. The light incident on the projection lens 119 is limited in luminous flux by the diaphragm 120 and the tilt diaphragm 121, and is enlarged and projected on the screen 122.

Now, the horizontal direction of the screen of the liquid crystal panel is the x-axis,
X where the vertical direction of the screen is the y-axis and the optical axis of the projection lens is the z-axis
Consider the yz orthogonal coordinate system. Liquid crystal panels 112, 113,
The chief ray passing through the center of the screen of 114 is tilted by several degrees with respect to the optical axis of the projection lens 119 so that the contrast is best. Therefore, the liquid crystal panels 112, 113, 114
Is the center of the screen with respect to the optical axis of the projection lens 119.
It is arranged so as to be displaced in the axial direction.

When the screen centers of the liquid crystal panels 112, 113 and 114 are arranged so as to be displaced in the y-axis direction with respect to the optical axis of the projection lens 119, the angle of view ω of the projection lens 119 with respect to the upper and lower screens of the projected image is different. Brightness unevenness occurs at the top and bottom of the screen. In order to improve the uneven brightness at the top and bottom of the screen,
The size of the aperture of the tilt diaphragm 121 and the tilt angle are adjusted.
In this way, it is possible to improve the brightness unevenness at the top and bottom of the screen as in the second embodiment.

Similarly, when the liquid crystal panels 112, 113, 114 shift their screen centers in the x-axis direction with respect to the optical axis of the projection lens 119, unevenness in brightness occurs in the projected image. In this case, since the brightness unevenness occurs in the horizontal direction of the screen 122, the tilt diaphragm 121 may be rotated and tilted about the y-axis, and the size and tilt angle of the opening of the tilt diaphragm 121 may be adjusted to obtain the projected image. It is possible to improve the uneven brightness.

In the third embodiment, similarly to the first embodiment, the tilt diaphragm 121 is the liquid crystal panel 11 of the diaphragm 120.
It may be arranged on the second side. The tilt diaphragm may be arranged on both the screen 122 side and the liquid crystal panel 112 side of the diaphragm 120. Further, by disposing a tilt diaphragm 71 (shown in FIG. 5) having a variable tilt angle and rotatable about the z axis on the projection lens 119, the liquid crystal panel 11 can be obtained.
It is possible to improve the brightness unevenness that occurs in the projected image when the image is projected in an arbitrary direction, depending on the amount of shift of the screen centers 2, 113 and 114 with respect to the projection lens 119.

Furthermore, in the third embodiment, even when the screen 122 is arranged to be inclined with respect to the optical axis of the projection lens 119, as in the second embodiment, the uneven brightness 71 ( (Shown in FIG. 5) can be used for improvement. The trapezoidal distortion may be corrected by changing the shape of the image using an image memory.

In the first to third embodiments, the example in which the twisted nematic liquid crystal panel is used for the light valve is shown, but other liquid crystal panel such as polymer dispersed liquid crystal can be used. The same effect can be achieved by using a light valve that forms an optical image according to a video signal as a change in birefringence or optical rotation such as electro-optical effect.

[0055]

As described above, the projection type display device of the present invention is provided with the tilt diaphragm in the projection lens, so that the aperture efficiency of the projection lens can be controlled with respect to an arbitrary point on the screen. . Further, by controlling the aperture efficiency of the projection lens, it is possible to realize an excellent projection display device in which the unevenness in brightness and the unevenness in color of the projected image on the screen caused by the difference in the angle of view of the projection lens are improved.

[Brief description of drawings]

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

FIG. 2 is a diagram for explaining an optical path of a projection lens according to the present invention.

FIG. 3 is a characteristic diagram for explaining the illuminance distribution of blue, green, and red projected images.

FIG. 4 is a diagram for explaining an optical path in the case where inclined diaphragms are arranged at two positions of the projection lens according to the present invention.

FIG. 5 is a diagram for explaining an optical path in the case where a diaphragm for varying the tilt angle and the rotation angle is arranged in the projection lens according to the present invention.

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

FIG. 7 is a schematic configuration diagram of a projection display device according to a third embodiment of the invention.

FIG. 8 is a schematic configuration diagram of a conventional projection display device using one projection lens.

FIG. 9 is a schematic configuration diagram of a conventional projection display device using three projection lenses.

FIG. 10 is an illuminance distribution characteristic diagram of blue, green, and red projected images of a conventional projection display device.

[Explanation of symbols]

34, 84, 104 Light source 38, 107 Color separation optical system 45, 46, 47, 89, 112, 113, 114 Liquid crystal panel 48, 49, 50, 90, 119 Projection lens 51, 53, 91, 120 Aperture 52, 54 , 92,121 Inclined diaphragm 55,93,122 Screen 118 Color synthesis optical system

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshito Miyatake 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (21)

[Claims] 1. A light source, a light valve that receives light emitted from the light source to form an optical image according to a video signal, and projection that receives light emitted from the light valve and projects the optical image on a screen. And a lens, wherein the light valve is disposed with its screen center displaced from the optical axis of the projection lens, and the projection lens has a diaphragm inclined with respect to the optical axis. 2. The projection lens comprises, in addition to a diaphragm inclined with respect to the optical axis, a diaphragm arranged at the intersection of the principal ray and the optical axis of the projection lens. Projection display device. 3. The projection display device according to claim 1, wherein the projection lens comprises a plurality of diaphragms inclined with respect to the optical axis. 4. A plurality of diaphragms tilted with respect to the optical axis are arranged on the screen side and the light valve side of the intersection of the principal ray and the optical axis of the projection lens, respectively. Item 3. The projection display device according to item 3. 5. The projection display device according to claim 1, wherein the tilted diaphragm has a variable tilt angle. 6. The projection display device according to claim 1, wherein the tilted diaphragm is rotatable about the optical axis of the projection lens. 7. The projection display device according to claim 1, wherein a liquid crystal panel is used as the light valve. 8. A light source, color separation means for separating white light emitted from said light source into light of blue, green and red color components, and light emitted from said color separation means into a video signal. The three light valves are provided with three light valves for forming corresponding optical images and three projection lenses for respectively receiving the light emitted from the respective light valves and projecting the respective optical images on a screen. At least two of the light valves are arranged with their screen centers displaced from the optical axis of the corresponding projection lens, and the corresponding projection lenses are diaphragms inclined with respect to the optical axis. A projection-type display device comprising: 9. A projection lens having a diaphragm tilted with respect to an optical axis, in addition to the tilted diaphragm, a projection arranged at a position where a principal ray and an optical axis of the projection lens intersect. The projection display device according to claim 8. 10. The projection display device according to claim 8, wherein the projection lens having an inclined diaphragm is provided with a plurality of diaphragms inclined with respect to the optical axis. 11. The projection according to claim 10, wherein the plurality of tilted diaphragms are arranged on the screen side and the light valve side of the intersection of the principal ray and the optical axis of the projection lens, respectively. Type display device. 12. The projection display device according to claim 8, wherein the tilted diaphragm has a variable tilt angle. 13. The projection display apparatus according to claim 8, wherein the tilted diaphragm is rotatable about the optical axis of the projection lens. 14. The projection display device according to claim 8, wherein a liquid crystal panel is used as the light valve. 15. A light source, color separation means for separating white light emitted from the light source into light of blue, green, and red color components, and light emitted from the color separation means according to a video signal. Three light valves on which an optical image is formed, a color synthesizing unit that receives light emitted from each of the light valves and synthesizes light of blue, green, and red color components, and light from the color synthesizing unit. And a projection lens for projecting on a screen, wherein each light valve is arranged such that its screen center is shifted from the optical axis of the corresponding projection lens, and the projection lens is arranged with respect to the optical axis of the projection lens. A projection-type display device, which is provided with an inclined diaphragm. 16. The projection lens according to claim 15, further comprising a diaphragm arranged at an intersection of a principal ray and an optical axis of the projection lens, in addition to the diaphragm inclined with respect to the optical axis. Projection display device. 17. The projection lens comprises a plurality of diaphragms inclined with respect to the optical axis.
5. The projection display device according to item 5. 18. The tilted diaphragm is arranged on the screen side and the light valve side of the intersection of the principal ray and the optical axis of the projection lens, respectively.
7. The projection display device according to 7. 19. The projection display device according to claim 15, wherein the plurality of tilted diaphragms have variable tilt angles. 20. The projection display device according to claim 15, wherein the tilted diaphragm is rotatable about the optical axis of the projection lens. 21. The projection display device according to claim 15, wherein a liquid crystal panel is used as the light valve.