JPH07117817B2 - LCD projection display - Google Patents

Description

[Detailed Description of the Invention] Industrial application In the case of a large-sized display to a certain extent, a conventional CRT alone is not only difficult to manufacture, but also heavy and long in depth, and consumes a large amount of power. . Therefore, three types of small, high-intensity CRTs for blue images, green images, and red images are lined up and a display for projecting each image on the screen has been put into practical use. Further, a projection display for projecting light from a light source as a color image on a screen through a color liquid crystal panel, which is thinner and lighter, has been developed. The present invention relates to this liquid crystal projection display.

2. Description of the Related Art Conventionally, liquid crystal projection displays use a high-output light source such as a xenon lamp or a metal halide lamp, which can obtain a relatively well-balanced light from the blue component to the red component in the visible wavelength range, such as a dichroic mirror. It is a system that separates blue, green, and red by the color separation system configured in (3), makes them enter the liquid crystal panel for each color image, and projects the three color images thus formed on the screen by the projection lens.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention As described above, the liquid crystal projection display has hitherto been a high-performance light source such as a xenon lamp or a metal halide lamp that can obtain light in a relatively well-balanced range from blue components to red components in the visible wavelength range. An output light source was used, and it was separated into blue, green, and red by a color separation system composed of dichroic mirrors and made to enter the liquid crystal panel for each color image. However, in color reproduction as a color display,
Color purity is poor because only blue, green and red spectra are obtained. In addition, the shutter action of the liquid crystal panel is that the incident light is polarized in the liquid crystal, and the polarization angle is controlled by the applied voltage to produce gradation, but this polarization angle changes depending on the wavelength of the incident light. There is a problem in that blue having a short wavelength increases the transmittance on the long wavelength side, and when a light source with a continuous spectrum is used, the color shift of the blue component of gradation is large. Even when a bright line light source is used, for example, a high-pressure mercury lamp has no bright line in the red component, and even with a three-component system metal halide lamp, the bright line on the long wavelength side of Na is about 590 nm, and good color reproduction for red is obtained. In addition, in the case of Li emission, a large amount of radiant energy can be obtained at 690 nm, but there is a problem that luminance cannot be obtained because it deviates from the luminosity.

In order to solve the above problems, in order to solve the above problems, a light source having emission lines near wavelengths 450 nm and 550 nm and emitting radiation in the ultraviolet region of wavelength 300 nm or less is contained in the condensing optical system, Of the radiation emitted from the optical system, only the ultraviolet radiation component is separated and guided to a panel coated with a red-emitting phosphor to emit light, which is then incident on a liquid crystal panel for red images, and the resulting red image is displayed on the screen. Then, the remaining blue and green emission lines are separated and made incident on the liquid crystal panel, and the color image formed thereby is projected on the screen.

By doing this, the large ultraviolet radiation energy of the high-output discharge lamp is used for red emission, so the energy efficiency of the lamp is improved, and the color shift due to the gradation of the blue component is that the blue component is a bright line. Since there is no light emission on the wavelength side, there is no energy of the wavelength from yellow to red that is transmitted and mixed from the color separation system or the liquid crystal panel, so that it is possible to improve.

Example As an example of the present invention, a light source optical system and a color separation optical system of a liquid crystal projection display using a high pressure mercury lamp using quartz glass as a light source in an outer bulb will be described with reference to the drawings. FIG. 1 shows a light source section optical system and a color separation optical system of a liquid crystal projection display. In the figure, reference numeral 1 denotes a high pressure mercury lamp using quartz glass for an outer bulb, and a condenser mirror 2 and a quartz lens optical system 3 collimate the radiation from the high pressure mercury lamp 1 and project it on the front surface of a light source unit.
Of the collimated light, a beam splitter 4 that reflects ultraviolet radiation components with a wavelength of 300 nm or less and transmits wavelength components with a wavelength of more than 300 nm separates only the ultraviolet radiation, and a red-emitting phosphor, for example, a sharp line spectrum around a wavelength of 620 nm. To a glass panel 5 coated with a rare earth phosphor (yttrium oxide phosphor) having a. A first liquid crystal panel 6 for producing an image of a red component is placed on the front surface of a glass panel 5 coated with the red light emitting phosphor that emits red light by ultraviolet radiation, and the image is projected on a screen 8 by a first projection lens 7. To do. Next, only the ultraviolet radiation is separated by the beam splitter 4, and the
The dichroic mirror 9 that reflects the radiation from 400 nm to 500 nm and transmits the other radiation reflects the mercury emission line with a wavelength of 435.8 nm and guides it to the second liquid crystal panel 10 that produces a blue component image, and the image is displayed as the second image. The image is projected on the screen 8 by the projection lens 11 of. Further, the radiation having a wavelength of 500 nm or more separated by the beam splitter 4 and the dichroic mirror 9 is changed in its optical path by a reflection mirror 12 and is passed through a filter 13 which transmits only a mercury emission line of wavelength 546.1 nm to produce a green component image. The image is guided to the liquid crystal panel 14, and the image is projected on the screen 8 by the third projection lens 15. The second
The figure shows the emission spectra of a high-pressure mercury lamp and a red-emitting rare earth phosphor (yttrium oxide phosphor).

Effects of the Invention According to the method described above, the large ultraviolet radiant energy possessed by the high-power discharge lamp is utilized as red light emission, whereby the energy efficiency of the lamp is improved, and the color shift due to the gradation of the blue component is also Since the blue component is a bright line and there is no light emission on the long wavelength side, there is no energy of the wavelength from yellow to red that is transmitted and mixed from the color separation system or liquid crystal panel, and it is possible to improve the color reproduction. A good projection display can be realized.

[Brief description of drawings]

FIG. 1 is an explanatory view of a light source optical system and a color separation optical system of a liquid crystal projection display as an embodiment of the present invention, and FIG. 2 is a high pressure mercury lamp and a red-emitting rare earth phosphor (yttrium oxide phosphor). FIG. 3 is an emission spectrum diagram of 1 ... High-pressure mercury lamp using quartz glass for outer bulb, 2 ... Focusing mirror, 3 ... Quartz lens optical system, 4 ...
... Beam splitter, 5 ... Glass panel coated with rare earth phosphor (yttrium oxide phosphor) having a sharp line spectrum around wavelength 620 nm, 6 ...
… The first liquid crystal panel that creates red component images, 7 ……
1st projection lens, 8 ... screen, 9 ... dichroic mirror, 10 ... second liquid crystal panel for producing blue component image, 11 ... second projection lens, 12 ... reflection mirror, 13 ... Filter, 14 ... 3rd liquid crystal panel that produces green component image, 15 ... 3rd projection lens.

Claims (1)

[Claims] 1. An ultraviolet radiation component of radiation emitted from the condensing optical system, in which a light source having emission lines near wavelengths of 450 nm and 550 nm and emitting radiation in the ultraviolet region of wavelength of 300 nm or less is contained in the condensing optical system. A red image consisting of a first projection lens that separates only the light and guides it to a panel coated with a red-light-emitting phosphor to cause it to emit light, which is then incident on the liquid crystal panel for the red image, and the resulting red image is projected onto the screen. The projection optical system and the radiation emitted from the condensing optical system are separated and removed only from the ultraviolet radiation component, and only the green component radiation is separated from the visible radiation and made incident on the liquid crystal panel for the green image, thereby forming the green color. A green image projection optical system consisting of a second projection lens for projecting an image on the screen, and a blue component radiation obtained by separating and removing the ultraviolet radiation component and the green component of the radiation emitted from the condensing optical system. Is incident on the liquid crystal panel for color images, the blue image projection optical system comprising a blue image made by it from the third projection lens for projecting on a screen,
A liquid crystal projection display consisting of the above three color image projection optical systems.