JP2002006298A - Projection color picture display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projection color picture display device having reduced color slippage caused by chromatic aberration due to magnification of a projection lens without increasing a manufacturing cost of the projection lens. SOLUTION: A synthetic prism 15 is provided with a correction lens 21 on its surface confronted with a liquid crystal panel 14b displaying a green image exhibiting a maximized image size. The correction lens 21 is a plano-concave lens with its recessing face placed opposite to the liquid crystal panel 14b side and integrally formed on an incident plane of the synthetic prism 15 by hybrid molding. The green image displayed on the liquid crystal panel 14b is reduced due to transmission through the correction lens 21 having negative refraction and is image formed on a screen 19 with the same size as those of a red image and a blue image.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type color image display device which combines three color lights of three images formed on three transmission type liquid crystal panels and projects it on a screen.

[0002]

2. Description of the Related Art There are various types of projection-type color image display devices. Generally, white light emitted from a light source is converted into red light, blue light, and green light. The three color lights are divided into three color lights, and each color light is made incident on three transmission type liquid crystal panels to display an image of a corresponding color, and the color lights of these three images are optically combined and projected on a screen. What was done. The transmissive liquid crystal panel includes light valves arranged for each pixel, and the density of an image can be controlled by adjusting the transmittance of each light valve.

FIG. 8 shows a general optical configuration of a projection type color image display device. The projection type color image display device includes two dichroic mirrors 12 and 13 for decomposing white light emitted from a light source lamp 11 into three color lights of red light, blue light and green light, and three transmission liquid crystals. Panels 14a, 14b, 14c and liquid crystal panel 14a
14C, a combining prism 15 for combining the color lights of the three images displayed on the screens 14 to 14c, a projection lens 16 for projecting the combined image on a screen (not shown), and a reflecting mirror 17. The first dichroic mirror 12 transmits red light in white light and reflects blue light and green light in a vertical direction. Also, the second dichroic mirror 13
Is disposed on the optical path of the combined light of the blue light and the green light, transmits the green light, and reflects the blue light in a vertical direction. The three liquid crystal panels 14a to 14c are arranged on the optical paths of the three color lights separated by the dichroic mirrors 12 and 13, respectively.
A red image, a blue image, and a green image are formed by adjusting the amount of transmitted light for each pixel.

The combining prism 15 is constituted by combining four right-angle prisms 15a, 15b, 15c and 15d. Each side surface of the right-angle prisms 15a to 15d is provided with a dichroic coating, so that the combiner 15 is formed with two intersecting dichroic surfaces 15e and 15f.

[0005] A total of three reflecting mirrors 17 are arranged in the optical path of red light and green light, and the optical path is bent so that the liquid crystal panels 14 a to 14 c face the three peripheral surfaces of the combining prism 15. The color lights of the three images formed on the liquid crystal panels 14a to 14c are combined by passing through the combining prism 15, and the combined image light is emitted to the projection lens 16 side.

[0006]

However, the red, blue, and green color lights formed on the liquid crystal panels 14a to 14c have different wavelengths.
Due to the chromatic aberration of magnification of the projection lens 16, the sizes of the red, blue, and green images formed on the screen are different from each other, and a color shift occurs in the color image. In the chromatic aberration of magnification, since the refractive index of the glass (lens) differs depending on the magnitude of the wavelength of light, the position and size of an image formed by light other than paraxial rays differ depending on the wavelength.

In order to eliminate the color shift on the screen, each of the liquid crystal panels 14a to 14c is displaced on the optical axis and the object distance of each of the liquid crystal panels 14a to 14c is adjusted, so that the size of the image of each color is adjusted. There is a way to adjust it. However, in this method, since the amount of displacement of each of the liquid crystal panels 14a to 14c increases as the projection magnification increases, the image on the screen becomes out of focus, and a sharp color image cannot be obtained.

Therefore, a method of optically correcting the chromatic aberration of magnification of the projection lens is generally adopted. However, in order to effectively correct the chromatic aberration of magnification of the projection lens, expensive anomalous dispersion glass is used as the material thereof, which causes an increase in the cost of the projection lens.

[0009] The present invention has been made in view of the above circumstances, without increasing the manufacturing cost of the projection lens.
It is an object of the present invention to provide a projection type color image display device in which a color shift caused by a chromatic aberration of magnification of a projection lens is reduced.

[0010]

In order to achieve the above object, a projection type color image display device according to the present invention comprises a screen provided on at least one of three incident surfaces of a combining prism on which three color lights are incident. A resin correction lens for correcting the size of the image of the color light so that the size of the image above becomes the same as the image of the other color light is integrally molded by a hybrid molding method.

According to a second aspect of the present invention, there is provided a projection type color image display device, wherein at least one of the first to third transmission type liquid crystal panels has an image size of another color light on the screen. A resin correction lens for correcting the size of an image of color light from the transmission type liquid crystal panel in the same manner as described above is integrally molded by a hybrid molding method.

According to a third aspect of the present invention, in the projection type color image display device, the size of the image on the screen is different from the size of the image on the screen by a transparent parallel plate disposed in at least one optical path of the three color lights. A resin correction lens for correcting the size of the color light image so as to be the same as the color light image is integrally molded by a hybrid molding method.

According to a fourth aspect of the present invention, in the projection type color image display device, the correction lens is formed of an ultraviolet curable resin.

According to a fifth aspect of the present invention, in the projection type color image display device, the thickness at the thinnest portion is 1 mm or less.
This is to form a correction lens.

[0015]

FIG. 1 shows an optical configuration of a projection type color image display device according to the present invention. The same members as those of the projection type color image display device shown in FIG. It is attached. The projection type color image display device of the present invention includes three light sources 11 for emitting white light and three filters 18.
a, 18b, 18c and three transmissive liquid crystal panels (hereinafter simply referred to as liquid crystal panels) 14a, 14b, 14c
, A combining prism 15 and a projection lens 16. The filter 18a transmits only the red component light in the white light emitted from the corresponding light source 11, and makes the red component light incident on the liquid crystal panel 14a. The filter 18b transmits green component light in white light, and the filter 18c transmits blue component light in white light.
Incident on

The synthesizing prism 15 is composed of four right-angle prisms 15a each having a dichroic coating on the side surface.
15b, 15c, and 15d are combined, and the peripheral surface on the right-angle prism 15a, 15b, and 15c side is an incident surface, and the peripheral surface on the right-angle prism 15d side is an exit surface. The three liquid crystal panels 14a, 14b, and 14c display a red image, a green image, and a blue image, and are arranged so as to face three incident surfaces of the combining prism 15. Liquid crystal panels 14a-
The color lights of the three images displayed on 14c are combined by passing through the combining prism 15, and the combined image light is emitted from the exit surface.

The projection lens 16 projects the combined image light from the combining prism 15 onto a screen 19. The projection lens 16 has a chromatic aberration of magnification such that the refracting power for the color light of the green image is significantly different from the refracting power for the respective color lights of the red image and the blue image, and the green image is formed larger than the other two images. .

The synthesizing prism 15 is provided with a correction lens 21 made of resin on the incident surface of the color light of the green image where the image size is the largest. The correction lens 21 is a plano-concave lens having a concave surface facing the liquid crystal panel 14b, and is integrally formed on the incident surface of the synthetic prism 15 by a hybrid molding method. In the present embodiment, the correction lens 21
Is molded using a resin having ultraviolet curability, and is formed into a spherical shape having a thickness of 0.2 mm at a central portion and a radius of curvature of 7500 mm.

FIG. 2 shows a method of forming the correction lens 21. As shown in FIG. 3A, a concave portion 51 is formed on the upper surface of the mold 50 for fitting the synthetic prism 15 with the surface on which the correction lens 21 is to be formed facing downward. The correction lens 2 is provided on the bottom surface of the concave portion 51.
A molding groove 52 having the same shape as 1 is formed. Correction lens 2
1 is formed, as shown in FIG.
The synthetic prism 15 is set in the mold 0 and an ultraviolet curing resin for molding is injected into the molding groove 52. Thereafter, when ultraviolet rays are irradiated from above the combining prism 15, the combining prism 1
The resin is cured by the ultraviolet light transmitted through the resin 5. Thereby, the correction lens 21 made of resin is provided on the surface of the synthetic prism 15.
Are integrally formed. In addition, the correction lens molded by the above method, considering the ease of molding,
It is preferable that the thickness at the thinnest part is 1 mm or less.

As described above, the size of a green image is larger than that of a red image and a blue image. The green image is reduced by passing the color light of the green image through the correction lens 21 having negative refractive power. This allows
The red image, the green image, and the blue image formed on the screen 19 by the projection lens 16 have the same size, and a good color image without color shift can be obtained.

In the present invention, since the correction lens is formed directly on the entrance surface of the combining prism, the thickness of the correction lens can be made extremely thin. As a result, the optical path length of the color light on which the correction lens is arranged does not change, so that it is not necessary to provide a parallel flat plate for correcting the optical path length in the optical path of the color light without the correction lens, thereby contributing to a reduction in apparatus cost. it can. In addition, since the lens surface of any shape can be easily formed by changing the shape of the molding groove of the mold, the curved surface shape of the correction lens may be an aspherical surface.

In the above embodiment, one of the combining prisms 15
Although the correction lens 21 having the function of reducing the image is provided on the incident surface, as shown in FIG. 3, the correction lens having the function of enlarging the image is formed on each of the light incident surfaces of the red image and the blue image. It is also possible to provide 26 and 27. Each of the correction lenses 26 and 27 has a convex surface formed on the liquid crystal panel 14.
a, a convex lens directed to the 14c side, and enlarges the size of the red image and the blue image so that they are the same size as the green image. The correction lens 26 has a thickness of 0.2 mm at the peripheral edge where the thickness is the smallest, and has a radius of curvature of 760.
It is configured to be 0 mm. The correction lens 27 has a thickness of 0.2 mm at the peripheral edge and a radius of curvature of 7700 mm.

Each color light of the red image and the blue image displayed on the liquid crystal panels 14a and 14c passes through the correction lens plates 26 and 27 having a positive refractive power as a whole.
The size of each image is enlarged. Thereby, the projection lens 1
6, the size of each of the red image, green image, and blue image formed on the screen 19 becomes the same, and a good color image without color shift can be obtained.

FIG. 4 shows another optical configuration of the projection type color image display device of the present invention. In this embodiment, the display surface of the liquid crystal panel 14b that displays a green image is
The correction lens 31 is integrally formed. The correction lens 31 is a plano-concave lens having a concave surface facing the synthetic prism 15 side, has a thickness at the center of 0.2 mm, and has a radius of curvature of 1.
It is configured to be 100 mm. Also in this embodiment, by forming the correction lens 31 integrally with the display surface of the liquid crystal panel 14b by the same method as the correction lens 21 shown in FIG. 1, the correction lens 31 having an extremely small thickness can be easily formed. Can be.

The color light of the green image displayed on the liquid crystal panel 14b passes through the correction lens 31 having a negative refractive power, so that the size of the image is reduced. As a result, the red image, the green image, and the blue image formed on the screen 19 by the projection lens 16 have the same size, and a good color image without color shift can be obtained.

As shown in FIG. 5, on each display surface of the liquid crystal panels 14a and 14c for displaying a red image and a blue image,
It is also possible to integrally form the correction lenses 35 and 36 having the function of enlarging an image. The correction lenses 35 and 36
Each of them is composed of a plano-convex lens having a convex surface facing the synthesis prism 15 side. The correction lens 35 is configured to have a thickness of 0.3 mm at a peripheral portion where the thickness is the thinnest and a radius of curvature of 900 mm. The correction lens 36 has a thickness at the peripheral portion of 0.3 mm and a radius of curvature of 950 mm.

Each color light of the red image and the blue image displayed on the liquid crystal panels 14a and 14c passes through the correction lenses 35 and 36 having positive refractive power, so that the size of each image is enlarged. As a result, the red image, the green image, and the blue image formed on the screen 19 by the projection lens 16 have the same size, and a good color image without color shift can be obtained.

FIG. 6 shows still another optical configuration of the projection type color image display device of the present invention. In this embodiment, the combining prism 15 and each liquid crystal panel 14a, 1
4b and 14c, between the polarizing substrates 41, 42,
43 are provided. The polarizing substrate 41 has a configuration in which a polarizing plate 41b is provided on the surface of the transparent parallel flat plate 41a on the liquid crystal panel 14a side. The polarizing substrate 4 provided between the combining prism 15 and the liquid crystal panels 14b and 14c.
2 and 43 have the same configuration as the polarizing substrate 41, and therefore, are denoted only by reference numerals.

A polarizing substrate 42 provided between the liquid crystal panel 14b for displaying a green image and the combining prism 15 has:
A correction lens 45 is integrally formed on the surface of the parallel plate 42a on the side of the synthesis prism 15. The correction lens 45 is a plano-concave lens whose concave surface faces the synthetic prism 15 side, and is integrally formed on the surface of the parallel flat plate 42a by the same method as the correction lens 21 shown in FIG. This correction lens 45
Has a thickness of 0.2 mm at the center and a radius of curvature of 6400
mm.

The color light of the green image displayed on the liquid crystal panel 14b passes through the correction lens 45 having a negative refractive power, so that the size of the image is reduced. As a result, the red image, the green image, and the blue image formed on the screen 19 by the projection lens 16 have the same size, and a good color image without color shift can be obtained.

As shown in FIG. 7, polarizing plates 41 and 43 provided between the liquid crystal panels 14a and 14c for displaying red and blue images and the synthesizing prism 15 have a function of enlarging the images. The correction lenses 46 and 47 may be integrally formed. Each of the correction lenses 46 and 47 is a plano-convex lens having a convex surface facing the composite prism 15 side, and is formed integrally with the surfaces of the parallel plates 41a and 43a on the composite prism 15 side. The correction lens 46 is configured to have a thickness of 0.2 mm at the peripheral edge where the thickness is the thinnest and a radius of curvature of 6500 mm. The correction lens 47 has a thickness at the peripheral edge of 0.2 mm and a radius of curvature of 6600 mm.

Each color light of the red image and the blue image displayed on the liquid crystal panels 14a and 14c passes through the correction lenses 46 and 47 having positive refractive power, so that the size of each image is enlarged. As a result, the red image, the green image, and the blue image formed on the screen 19 by the projection lens 16 have the same size, and a good color image without color shift can be obtained.

In each of the above-described embodiments, a correction lens for reducing the size of the green image or a correction lens for reducing the size of the green image is used based on the size of the green image in which the size of the image on the screen is particularly large. Although an example in which any of the correction lenses for enlarging the size of the image other than the above is provided has been described, in the present invention, since the images of the respective color lights only need to be formed on the screen with the same size, A correction lens for reducing the size and a correction lens for expanding the size may be used in an appropriate combination.

In each of the above embodiments, a dedicated light source is provided for each of the three liquid crystal panels. However, as shown in FIG. 8, white light emitted from one light source is converted to red light and blue light. Of course, the present invention can also be applied to a color image display device in which three color lights of green light and green light are decomposed and each of the color lights enters three liquid crystal panels.

[0035]

As described above, according to the projection type color image display device of the present invention, at least one of the color lights of three images is provided.
In one optical path, a resin correction lens for correcting the size of the image of the color light so that the size of the image on the screen is the same as the image of the other color light is provided, so that the chromatic aberration of magnification of the projection lens is provided. A good color image without color shift can be formed on a screen without optically correcting the color. This eliminates the need to use expensive anomalous dispersion glass as a material for the projection lens, and can suppress an increase in the cost of the projection lens.

In addition, an extremely thin correction lens is formed by integrally molding the correction lens on the entrance surface of the synthetic prism, the display surface of the transmission type liquid crystal panel, or a parallel flat plate disposed in the optical path of the color light. Therefore, even if this correction lens is provided, the optical path length does not change. Thereby, the optical path lengths of the three color lights become the same length without specially providing a parallel plate for optical path length correction which has been generally used conventionally, without causing a defocus of each color image.
A good color image with corrected color shift can be formed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an optical configuration of a projection type color image display device of the present invention.

FIG. 2 is an explanatory diagram showing a method of forming the correction lens shown in FIG.

FIG. 3 is a schematic diagram showing another arrangement example of a correction lens in the projection type color image display device of FIG.

FIG. 4 is a schematic diagram showing another optical configuration of the projection type color image display device of the present invention.

5 is a schematic view showing another example of the arrangement of the correction lens plate in the projection type color image display device of FIG.

FIG. 6 is a schematic diagram showing still another optical configuration of the projection type color image display device of the present invention.

FIG. 7 is a schematic diagram showing another example of the arrangement of the correction lenses in the projection type color image display device of FIG.

FIG. 8 is a schematic diagram showing an optical configuration of a conventional projection type color image display device.

[Explanation of symbols]

Reference Signs List 11 light source 14a, 14b, 14c transmissive liquid crystal panel 15 synthetic prism 16 projection lens 19 screen 21, 26, 27, 31, 35, 36, 45, 46, 4
7 Correction lens 41, 42, 43 Polarizing substrate 41a, 42a, 43a Parallel plate

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H088 EA12 HA18 HA23 HA24 HA28 MA20 2H091 FA05X FA08X FA08Z FA21X FA26X FA41Z FB04 LA15 LA30 MA07

Claims (5)

[Claims] 1. A first to a third transmissive liquid crystal panel for displaying an image of a corresponding color upon incidence of red light, blue light, and green light, and an image of each image formed on each transmissive liquid crystal panel. In a projection type color image display device provided with a combining prism for combining color lights and a projection lens for projecting the color light from the combining prism onto a screen, of the three incident surfaces of the combining prism on which the three color lights enter. In at least one, a resin correction lens for correcting the size of the image of the color light so that the size of the image on the screen is the same as the image of the other color light is integrally molded by a hybrid molding method. A projection type color image display device characterized by the above-mentioned. 2. A first to a third transmissive liquid crystal panel for displaying an image of a corresponding color upon incidence of red light, blue light and green light, and an image of each image formed on each transmissive liquid crystal panel. A projection type color image display device comprising: a combining prism for combining color light; and a projection lens for projecting the color light from the combining prism onto a screen, wherein at least one of the first to third transmission type liquid crystal panels is displayed. On the surface, a resin correction lens for correcting the size of the color light image from the transmission type liquid crystal panel so that the size of the image on the screen is the same as the image of the other color light, by a hybrid molding method A projection type color image display device characterized by being integrally formed. 3. A first to third transmissive liquid crystal panel for displaying an image of a corresponding color upon incidence of red light, blue light, and green light, and an image of each image formed on each transmissive liquid crystal panel. In a projection type color image display device including a combining prism for combining color lights and a projection lens for projecting the color light from the combining prism onto a screen, a transparent color light disposed in at least one optical path of the three color lights On the surface of the parallel plate, a resin correction lens for correcting the size of the image of the color light so that the size of the image on the screen becomes the same as the image of the other color light was integrally molded by a hybrid molding method. A projection type color image display device characterized by the above-mentioned. 4. The projection type color image display device according to claim 1, wherein the correction lens is made of an ultraviolet curable resin. 5. The projection type color image display device according to claim 1, wherein the correction lens has a thickness at a thinnest portion of 1 mm or less.