JPH10148896A - Projection type display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bright projection type display device which is excellent in color uniformity by correcting chromatic aberration. SOLUTION: When light emitted from a lamp 120 is made to be in parallel with a green color by a single condenser lens 131 in the optical path of the illumination light of the light valve of a projector, the light of a red color becomes the divergent light and the light of a blue color becomes the convergent light. Then, the illumination light of three primary colors R, G and B are made to be in parallel with one another and the color display characteristic of a projection picture is uniformized within a screen by inserting a convex lens 16 in the optical path of the red illumination light and inserting a concave lens 17 in the optical path of the blue illumination light.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection display device for eliminating color unevenness.

[0002]

2. Description of the Related Art As an example of the prior art, a projection display device using a liquid crystal panel will be described with reference to FIG. FIG. 2 shows an apparatus disclosed in, for example, Japanese Patent Application Laid-Open No. 1-26687. In FIG. 2, reference numeral 1 denotes a light source device, which includes a lamp 120, a spherical mirror 130, and a condenser lens 131. 2 is an illumination light beam emitted from the light source device 1, 14B, 14R
Is a dichroic mirror, 11a, 11b, 11c, and 11d are mirrors, 3R, 3G, and 3B are liquid crystal panels, 15 is a dichroic prism, 4 is a projection lens, and 5 is a screen.

Next, the operation will be described. As the lamp 120 used in the light source device 1, for example, a white light source such as a metal halide lamp, a xenon lamp, and a halogen lamp is used. By arranging the lamp 120 at the focal position of the condenser lens 131, a parallel illumination light beam 2 can be obtained. The reflecting surface of the spherical mirror 130 is typically a spherical surface. By setting the center of curvature of the spherical mirror 130 near the focal position of the condenser lens 131 (that is, the position of the lamp 120), the light beam 2 emitted from the condenser lens 131 Is known to be about twice as large as without the spherical mirror 130.

The illumination light beam 2 is separated into three primary colors of red, green and blue by a dichroic mirror 14B which reflects blue light and transmits green and red light, and a dichroic mirror 14R which reflects red light and transmits green and blue light. Is done. Red light mirror
The blue light is bent by the mirrors 11b and 11c and irradiated on the liquid crystal panel 3R, and the blue light is bent by the mirrors 11a and 11d and irradiated on the liquid crystal panel 3B. The green light is directly applied to the liquid crystal panel 3G. LCD panels 3R, 3G, 3B have red, green,
An image corresponding to each of the blue primary colors is displayed, but a drive circuit for displaying the image is not shown. The luminous flux modulated by the image formed on the liquid crystal panel selectively combines red and blue light, and is again combined into a single luminous flux by a known dichroic prism 15 that selectively transmits green light, thereby forming a projection lens. The light is converted into projection light 110 by 4 and is enlarged and projected on the screen 5.

[0005]

When the condenser lens 131 for converting the light emitted from the lamp 120 into parallel light is constituted by a single lens, the parallelism of the illumination light beam 2 after passing through the condenser lens 131 varies depending on the light wavelength. This is due to aberration (chromatic aberration) caused by a change in the refractive index of the lens material depending on the wavelength of light. When the condenser lens 131 is designed so that the parallelism is optimal in green light, which is the central wavelength region of visible light, blue light on the short wavelength side becomes focused light,
The red light on the long wavelength side becomes divergent light, and the illumination states of the three liquid crystal light valves (liquid crystal panels 3R, 3G, 3B) are different.
Condenser lens in projection display of prior art
The optical path length from 131 to the liquid crystal light valve is such that the red and blue light paths are about three times longer than the green light path. Since red light is divergent light and has a long optical path length, the decrease in illuminance on the liquid crystal light valve surface is more remarkable than green light. On the other hand, since the blue light is a convergent light, the projected image on the screen 5 has a color unevenness in which the center is bluish.

The present invention has been made in view of such circumstances, and has as its object to provide a projection display device having high luminance and excellent color uniformity.

[0007]

According to the present invention, there is provided a projection display apparatus comprising: a lamp for white light; a light source device comprising a spherical mirror and a condenser lens; and a light source for three primary colors of red, green and blue. A color separating means for separating the image into a rectangular aperture, a color synthesizing means for synthesizing red, green, and blue images, and a projection lens for enlarging and projecting the display image of the image display device. The difference in the parallelism of the illumination light due to the wavelength generated due to chromatic aberration is corrected by inserting a concave lens in the optical path of the color that is the convergent light and inserting a convex lens in the optical path of the color that is the divergent light. is there. Specifically, when a condenser lens is designed so that the parallelism is optimal in the optical path of green light, which is the central wavelength region of visible light, a convex lens is inserted into the optical path of red light on the long wavelength side that becomes divergent light. Then, a concave lens is inserted into the optical path of the blue light on the short wavelength side that becomes the focused light.

According to the projection display device of the present invention, since the parallelism of the illuminating light is corrected by the lens, the illuminance on the surface of the liquid crystal light valve is reduced due to the difference in the optical path length, and the three liquid crystal light valves are reduced. Illumination non-uniformity is eliminated.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings showing the embodiments. FIG. 1 is a diagram showing a configuration of a projection display device of the present invention. In FIG. 1, reference numeral 1 denotes a light source device, for example, a lamp 120 including a white light source such as a metal halide lamp, a xenon lamp, and a halogen lamp.
And a spherical mirror 130 whose reflection surface is typically spherical and a condenser lens 131. The center of curvature of the spherical mirror 130 is set near the focal position of the condenser lens 131 (that is, the position of the lamp 120). 2 is an illumination light beam emitted from the light source device 1, and 14B reflects blue light and
A dichroic mirror that transmits red light, 14R is a dichroic mirror that reflects red light and transmits green and blue light,
11a, 11b, 11c, and 11d are mirrors, 3R, 3G, and 3B are liquid crystal panels that display images corresponding to the primary colors of red, green, and blue, and 15 is a device that selectively reflects red and blue light and emits green light. A selectively transmitting dichroic prism, 4 is a projection lens, and 5 is a screen. In addition, dichroic mirror 14R and mirror
A convex lens 16 is provided between the light source 11b and the optical path of red light.
A concave lens 17 is provided between the dichroic mirror 14B and the mirror 11a (the optical path of blue light).

A lamp is provided at the focal position of the condenser lens 131.
By arranging 120, a parallel illumination light beam 2 is obtained. The illumination light beam 2 is separated into three primary colors of red, green and blue by dichroic mirrors 14R and 14B. Red light mirror
The liquid crystal panel 3R is irradiated through the mirror 11b, the convex lens 16, and the mirror 11c, and the blue light is irradiated onto the liquid crystal panel 3B through the mirror 11a, the concave lens 17, and the mirror 11d. The green light is directly applied to the liquid crystal panel 3G. Images corresponding to the primary colors of red, green, and blue are displayed on the liquid crystal panels 3R, 3G, and 3B. The light beams modulated by the images formed on the liquid crystal panels 3R, 3G, and 3B are combined into one light beam again by the dichroic prism 15, converted into the projection light 110 by the projection lens 4, and enlarged and projected on the screen 5. Is done.

Lamp 120, spherical mirror 130, condenser lens 13
1 comprises a condenser lens 131
Is composed of a single lens, the parallelism of the illumination light beam 2 differs depending on the wavelength of the light due to chromatic aberration as described above. When the condenser lens 131 is designed so that the parallelism is optimal in green light, which is the central wavelength region of visible light, blue light on the short wavelength side becomes focused light and red light on the long wavelength side becomes divergent light. And the three liquid crystal light valves have different illumination states.

In the present invention, in order to correct the parallelism, the red, green, and blue lights are separated by the dichroic mirrors 14B and 14R, and then the convex lens 16 is provided on the red light path of the divergent light,
A concave lens 17 is inserted into the light to correct the parallelism of each light.

In order to reduce the chromatic aberration, a material having a small refractive index dispersion (a large Abbe number) may be used as the material of the condenser lens 131. However, a material having a small refractive index dispersion generally has a small refractive index, so that light is condensed. It becomes difficult to design a lens having a large angle θ and a high light-collecting efficiency. Conversely, if a material having a high refractive index is used, it is easy to design a lens having a large converging angle θ, but the dispersion of the refractive index is large (the Abbe number is small),
The chromatic aberration is large, and the correction lenses 16 and 17 having strong power are required.

The present inventors have previously described the Aglas material FD13
A condenser lens having a focal length of 26.6 mm according to (Abbe number 27.8) was proposed in Japanese Patent Application No. 5-93141. When this condenser lens is applied to the light source device of the projection display device, the focal length of blue light and that of red light are different by about 1 mm.

Blue light is about 1400mm on the condenser lens transmission side
At the point where the red light is
It becomes divergent light having a focal point at 1400 mm. If a correction lens is provided at a position 100 mm after passing through the condenser lens 131, a concave lens 17 having a focal length of about 1300 mm is provided in the blue light path,
In the red light path, a convex lens 16 having a focal length of about 1500 mm may be used.

Since the correction lens is applied to monochromatic light, the refractive index and Abbe number of the material do not matter in particular. If a glass material is used, BK7 is used. If a plastic material is used, polymethyl methacrylate (PMMA) or polycarbonate (PC) is used. Low cost.

The lens is not limited to a spherical lens, but if a Fresnel lens is used, the optical system becomes compact.

[0018]

As described in detail above, according to the present invention, since the parallelism of the illumination light is corrected by the concave lens and the convex lens, the chromatic aberration can be corrected, and the high color uniformity can be achieved. A projection display device with high luminance can be realized.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a projection display device of the present invention.

FIG. 2 is a diagram illustrating a configuration of a conventional projection display device.

[Explanation of symbols]

1. Light source device, 3R, 3G, 3B liquid crystal panel, 4 projection lens, 14R, 14B dichroic mirror, 15 dichroic prism, 16 convex lens, 17 concave lens, 120 lamp, 130 spherical mirror, 131 condenser lens.

Claims (2)

[Claims] 1. A light source device comprising a lamp for emitting white light, a spherical mirror and a condenser lens, and a color separating means for separating white light emitted from the light source device into light of three primary colors of red, green and blue. An image display device for forming images of three primary colors of red, green and blue; a color synthesizing means for synthesizing images of the three primary colors of red, green and blue; and a projection lens for enlarging and projecting the image. A projection display device, wherein a concave lens or a convex lens is inserted into two of three optical paths after the primary colors are separated. 2. The parallelism of the incident light by the condenser lens is set to be optimal at the wavelength of green light,
2. The projection display device according to claim 1, wherein a convex lens is inserted in an optical path of red light and a concave lens is inserted in an optical path of blue light among the three optical paths.