JPH09160017A - Projection type video display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a video display device capable of projecting an enlarged fine image free from a color shade. SOLUTION: A spike filter 180 having characteristics capable of removing the boundary parts of respective color wavelength components is arranged on a part on which the optical paths of at least two colors are overlapped and the wavelength of the filter 180 is set up in red, green and blue optical path dichroic mirror spectral characteristics so as to remove shifted parts. Thereby even when the red, green and blue optical path dichroic mirror spectral characteristics are shifted due to incident angle dependence, the red, green and blue optical path dichroic mirror spectral characteristics are not changed and an image free from uneaven color can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type image display device, and more particularly to a three-plate type projection type image display device for separating or synthesizing white color by a dichroic mirror or a dichroic prism.

[0002]

2. Description of the Related Art A conventional three-panel projection type image display device will be described below with reference to FIG. A conventional projection type liquid crystal display device is disclosed in Japanese Patent Laid-Open No. 3-103.
As described in Japanese Patent Publication No. 842, the UV / IR filter 520 emits the luminous flux emitted from the metal halide lamp 510.
After removing harmful ultraviolet rays and infrared rays with, the two color separation dichroic mirrors 531 and 532 and the three aluminum reflection mirrors 541, 542 and 543 separate into three colors of red, green and blue. 3 liquid crystal panels 561,5 by light
62,563 is irradiated, and liquid crystal panels 561,562,5
In the projection type liquid crystal display device in which the light modulated into the image by 63 is combined by the cross dichroic prism 533 and projected on the screen by the projection lens 570, a narrow band filter 580 is provided in the green optical path. The dichroic mirror is one in which a multilayer film is vapor-deposited on a glass surface and obtains light in a desired wavelength band by reflection or transmission by utilizing light interference.

[0003]

However, since a metal halide lamp is not a point light source in a projection type liquid crystal display device in which colors are separated and combined by using a dichroic mirror, a light beam other than 45 ° is incident on the dichroic mirror. Although not shown in the prior art, a condenser lens is generally arranged immediately before or after the liquid crystal panel in order to increase the illuminance around the projection screen. In this case, the incident angle of the light beam to the cross dichroic prism for color combination is
As shown in FIG. 8, the light passing through the liquid crystal panel causes a difference in the incident angle to the dichroic mirror within the surface of the liquid crystal panel. Depending on the angle of light incident on the dichroic mirror, the spectral characteristic shifts to the long wavelength side when the incident angle of the light to the dichroic mirror decreases, and the spectral characteristic shifts to the short wavelength side when the incident angle increases, as shown in FIG. Therefore, there is a problem in that projection causes color unevenness on the surface. Therefore, in the technique disclosed in Japanese Patent Application Laid-Open No. 3-103842, a narrow band filter is arranged in the green optical path to remove the influence of the spectral characteristic shift due to the incident angle dependency of the dichroic mirror, but it is effective only in green. However, in order to reduce color unevenness with respect to other colors, it is necessary to add a narrow band filterer, and there is a problem that a large number of narrow band filterers are required.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a projection type image display apparatus in which the number of filters for the purpose of correcting color unevenness is small and a good quality image free from color unevenness can be obtained.

[0005]

A projection type image display device of the present invention removes harmful ultraviolet rays and infrared rays from a light beam emitted from a light source, and then converts the light rays into three primary colors of red, green and blue by a dichroic mirror or a dichroic prism. In a projection-type image display device that separates and combines light modulated into an image by an image modulation means with a dichroic mirror or a dichroic prism, and projects it on a screen with a projection lens, in an optical path in which at least two of the three primary colors overlap, It is characterized in that a filter having a characteristic of removing the boundary portion of each color wavelength is arranged.

[0006]

DETAILED DESCRIPTION OF THE INVENTION The present invention will now be described in detail with reference to the drawings.

FIG. 1 is an explanatory diagram of an example of an embodiment of the present invention. In the figure, after removing harmful ultraviolet rays and infrared rays from the light flux emitted from the metal halide lamp 110 with the UV / IR filter 120, the separation side red transmission dichroic mirror 131 and the separation side blue transmission dichroic mirror 132 and 1
The sheet is separated into three colors of red, green and blue by the separation side aluminum reflection mirror 141. The respective separated lights are converged by the three condenser lenses 151, 152, 153 to illuminate the three liquid crystal panels 161, 162, 163. LCD panel 1
The light modulated by the reference numerals 61, 162 and 163 and containing the image information is combined by the combining side red transmissive dichroic mirror 133, the combining side blue transmissive dichroic mirror 134 and the combining side aluminum reflecting mirror 142, and a screen (not shown) by the projection lens 170. Project on top. In the present invention, UV / IR
After the cut filter 120, a filter (hereinafter referred to as a spike filter) 180 having a characteristic of removing the red / green boundary and the green / blue boundary is arranged.

The setting of the spectral transmittance of the dichroic mirror used in this embodiment is shown in FIGS. The half-value wavelength of the separation side red transmission dichroic mirror 131 is 580 nm.
And the half-value wavelength of the separation-side blue transmission dichroic mirror 132 was set to 500 nm. Furthermore, the half-value wavelength of the synthetic side red transmission dichroic mirror 133 is set to 580 nm.
And the half-value wavelength of the combining side blue transmission dichroic mirror 134 was set to 500 nm.

FIG. 6 is an explanatory diagram of the operation principle of this embodiment, and the principle of the present invention will be described with reference to this figure. In the composite-side red transparent dichroic mirror 133 and the composite-side blue transparent dichroic mirror 134, the condenser lens 15 is used.
Due to the convergence of light by 1, 152 and 153, a difference in incident angle occurs within the dichroic mirror surface, and a shift in spectral characteristics occurs due to the incident angle dependency. Transmittance of separation-side red transmissive dichroic mirror 131, reflectance of separation-side aluminum reflective mirror 141, transmittance of composite-side red transmissive dichroic mirror 133, and composite-side blue transmissive dichroic mirror 1
A characteristic obtained by multiplying the reflectance of 34 (hereinafter referred to as red light path dichroic mirror spectral characteristic), the reflectance of the separation side red transmission dichroic mirror 131, the reflectance of the separation side blue transmission dichroic mirror 132, and the synthesis side red transmission dichroic. Characteristics obtained by multiplying the reflectance of the mirror 134 and the reflectance of the composite-side blue transmission dichroic mirror 134 (hereinafter referred to as the green optical path dichroic mirror spectral characteristic), the reflectance of the separation-side red transmission dichroic mirror 131 and the separation-side blue transmission The characteristic obtained by multiplying the transmittance of the dichroic mirror 132, the reflectance 142 of the composite-side aluminum reflection mirror, and the transmittance of the composite-side blue-transmission dichroic mirror 134 (hereinafter referred to as the blue optical path dichroic mirror spectral characteristic) is incident angle dependence. Shifts to the one-dot chain line characteristics in the figure The spike filter sets the wavelength so as to remove the half value wavelength shift of the red optical path dichroic mirror spectral characteristic, the green optical path dichroic mirror spectral characteristic, and the blue optical path dichroic mirror spectral characteristic. As a result, even if the red optical path dichroic mirror spectral characteristics, the green optical path dichroic mirror spectral characteristics, and the blue optical path dichroic mirror spectral characteristics shift due to the incident angle dependence, the red optical path spectral characteristics, green optical path spectral characteristics, and blue optical path spectral characteristics change. Without it, it is possible to obtain an image without color unevenness.

In the embodiment shown in FIG. 1, the separation-side red transmission dichroic mirror 131 and the metal halide lamp 110.
The spike filter 180 is arranged between the projection lens 170 and the blue transmission dichroic mirror 13 on the composite side.
The same effect can be obtained by arranging between 4 and 4. Further, it may be arranged between the separation-side red transmission dichroic mirror 131 and the separation-side blue transmission dichroic mirror 132, and in this case, the effect of reducing color unevenness for green and blue can be obtained.
Further, it may be arranged between the composite-side red transmissive dichroic mirror 133 and the composite-side blue transmissive dichroic mirror 134. In this case, the effect of reducing color unevenness in red and green can be obtained.

Further, although the color separation / combination optical system using the dichroic mirror has been described in the present embodiment, the same effect can be obtained also in the color separation / combination optical system using the dichroic prism.

Further, in the present embodiment, the liquid crystal is used as a means for modulating light into an image, but the same effect can be obtained by using an element for modulating light into an image by other means.

[0013]

As described above, the projection type image display device of the present invention is
By arranging the spike filter having the characteristic of removing the boundary portion of each color wavelength in the portion where the optical paths of at least two colors overlap, it is possible to obtain a good quality image without color unevenness.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing a spectral transmittance of a separation-side red transmission dichroic mirror in FIG.

FIG. 3 is a diagram showing the spectral transmittance of the separation-side blue transmission dichroic mirror in FIG.

FIG. 4 is a diagram showing the spectral transmittance of the synthetic red transmission dichroic mirror in FIG.

5 is a diagram showing the spectral transmittance of the composite-side blue transmission dichroic mirror in FIG.

FIG. 6 is an explanatory diagram of spectral characteristics of a color unevenness reduction filter and separation-side and combination-side dichroic mirrors according to the present invention.

FIG. 7 is a diagram showing a configuration of a conventional projection type liquid crystal projector.

FIG. 8 is an explanatory diagram of an angle of a light beam incident on a combining side dichroic mirror.

FIG. 9 is an explanatory diagram showing an incident angle dependency of a dichroic mirror.

[Explanation of symbols]

 110 Metal Halide Lamp 120 UV / IR Cut Filter 131 Separation Side Red Transmission Dichroic Mirror 132 Separation Side Blue Transmission Dichroic Mirror 133 Synthesis Side Red Transmission Dichroic Mirror 134 Synthesis Side Blue Transmission Dichroic Mirror 141 Separation Side Aluminum Reflection Mirror 142 Synthesis Side Aluminum Reflection Mirror 151 , 152, 153 Condenser lens 161 Liquid crystal panel for red 162 Liquid crystal panel for green 163 Liquid crystal panel for blue 170 Projection lens 180 Spike filter

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location H04N 9/31 H04N 9/31 C

Claims (5)

[Claims] 1. After removing harmful ultraviolet rays and infrared rays from a light flux emitted from a light source, the light is separated into three primary color lights of red, green, and blue by a dichroic mirror or a dichroic prism, and the light modulated into an image by an image modulating means is converted. In a projection image display device that combines a dichroic mirror or a dichroic prism and projects it on a screen with a projection lens, a filter that removes the boundary portion of each color wavelength is placed in the optical path where at least two of the three primary colors overlap. A projection-type image display device characterized in that 2. The projection type image display apparatus according to claim 1, wherein the filter is arranged in an optical path where the three primary colors of red, green and blue overlap. 3. The projection type image display apparatus according to claim 2, wherein the filter is arranged in an optical path after removing ultraviolet rays and infrared rays. 4. The projection display apparatus according to claim 2, wherein the filter is arranged in an optical path in front of the projection lens. 5. The projection image display apparatus according to claim 1, wherein the filter has a characteristic of removing a half value wavelength shift in the separation wavelength regions of at least two three primary colors.