JPH01283586A - Liquid crystal projection type display - Google Patents

Abstract

PURPOSE:To improve the energy efficiency of a lamp by separating luminescent components from a convergence optical system which contains a specific light source and emitting the light of a panel which is coated with respective color fluorescent materials of red, blue, and green luminesce, making its light incident on liquid crystal panels for respective color images, and projecting the formed color images on a screen. CONSTITUTION:The light source which has bright line radiation of almost 450 and 550nm in wavelength and emits light in a <=300nm wavelength ultraviolet-ray range is put in the convergence optical system, only an ultraviolet luminescent component is separated from the convergence optical system and guided to the panel 5 coated with a red fluorescent material, and the panel luminesces; and its light is made incident on a liquid crystal panel 6 for a red image, which is thus formed and projected on the screen. Then only a red component is separated from visible light from which only the ultraviolet luminescent component is removed and made incident on a liquid crystal panel 14 for a green image; and a blue component obtained by separating and removing the ultraviolet luminescenent component and green component is made incident on a liquid crystal panel 10 for a blue image, so that the green and blue images which are formed as mentioned above are projected on the screen 8. Consequently, the energy efficiency of the lamp is improved.

Description

[Detailed Description of the Invention] For large displays that are used in industrial fields, if they are constructed from a single conventional CRT, it is not only difficult to manufacture, but also heavy and long, and consumes a lot of power. . For this reason, displays have been put into practical use in which three types of small, high-brightness CRTs are lined up for blue images, green images, and red images, and the respective images are projected onto a screen. moreover,
A thinner and lighter projection blade display has been developed that projects light from a light source onto a screen as a color image through a color liquid crystal panel.

The present invention relates to this liquid crystal projection display.

Conventional technology Up until now, LCD projection displays have used a high-output light source such as a xenon lamp or a metal halide lamp that produces relatively balanced light from blue to red components in the visible wavelength range, and a dichroic mirror. The system used a color separation system consisting of a color separation system to separate blue, green, and red, and then input the images into a liquid crystal panel for each color image.The resulting three-color image was then projected onto a screen using a projection lens. .

Problems to be Solved by the Invention As stated above, until now, liquid crystal projection displays have used high-speed light sources such as xenon lamps and metal halide lamps in the light source section, which can provide relatively well-balanced light from blue to red components in the visible wavelength range. Using the output light source, the light was separated into blue, green, and red using a color separation system made up of dichroic mirrors, etc., and then incident on a liquid crystal panel for each color image. However, in color reproduction as a color display, blue,
Color purity is poor because only broad spectra can be obtained for both green and red. In addition, the shutter action of a liquid crystal panel is such that the incident light is polarized within the liquid crystal, and the polarization angle is controlled by an applied voltage to produce gradations, but this polarization angle changes depending on the wavelength of the incident light, and in particular, For short blue wavelengths, the transmittance increases at long wavelengths, and when a continuous spectrum light source is used, there is a problem that the color shift of the blue component at the bottom of the gradation is large. Furthermore, even when using an emission line light source, for example, a high-pressure mercury lamp does not have an emission line in the red component, and even with a three-component metal halide lamp, the emission line on the longer wavelength side of Na is currently around 590 nm, which does not provide good color reproduction for red. Furthermore, with the light emission of Li, a large amount of radiant energy can be obtained at 890 nm, but there is a problem in that the brightness cannot be changed because it deviates from the visibility.

Means to Solve the Problems In order to solve the above problems, wavelengths of 450 nm and 5
A light source that has bright line emission near 50 nm and emits radiation in the ultraviolet region with a wavelength of 300 nm or less is housed in a condensing optical system, and only the ultraviolet radiation component of the radiation emitted from the condensing optical system is separated to produce a red-emitting phosphor. The emitted light is directed to a panel coated with light and emitted, the emitted light is incident on a liquid crystal panel for red images, the resulting red image is projected onto a screen, and the remaining blue and green emission lines are also separated and sent to the liquid crystal panel. and project the resulting color image onto a screen.

Effect: Since the large ultraviolet radiation energy of a high-output discharge lamp is used for red light emission, the energy efficiency of the lamp is improved, and the color shift caused by the gradation of the blue component is also long because the blue component is a bright line. Since there is no light emission on the wavelength side, there is no energy of wavelengths from yellow to red that is transmitted through the color separation system or liquid crystal panel and mixed in, making it possible to improve this.

Embodiment As an embodiment 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 having an outer bulb made of quartz glass as a light source will be described with reference to the drawings. FIG. 1 shows a light source 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 whose outer bulb is made of quartz glass. A condensing mirror 2 and a quartz lens optical system 3 convert the radiation from the high-pressure mercury lamp 1 into parallel light and project it onto the front surface of the light source.

Of the parallel light, only the ultraviolet radiation is separated by the beam splitter 4, which reflects the ultraviolet radiation component with a wavelength of 300 nm or less and transmits the wavelength component with a wavelength longer than 300 nm. It leads to a glass panel 5 coated with a rare earth phosphor (yttrium oxide phosphor). A first liquid crystal panel 6 that produces a red component image is placed in front of the glass panel 5 coated with the red light-emitting phosphor that emits red light due to ultraviolet radiation, and the image is projected onto a screen 8 by a first projection lens 7. do. Next, the beam splitter 4 separates only the ultraviolet radiation, and out of the remaining radiation in the visible wavelength range, a dichroic mirror 9 that reflects radiation in the wavelength range of 400 nm to 500 nm and transmits the other radiation is used to separate the radiation in the wavelength range of 435.8 nm. The mercury bright line is reflected and guided to a second liquid crystal panel 10 that produces a blue component image, and the image is projected onto a screen 8 by a second projection lens 11. Furthermore, the beam splitter 4 and the dichroic mirror 9
Reflection mirror 1
2 changes the optical path, passes through a filter 13 that transmits only the mercury bright line with a wavelength of 546.1 nm, and guides it to a third liquid crystal panel 14 that produces an image of the green component, and projects the image onto a screen 8 using a third projection lens 15. do. FIG. 2 shows the emission spectra of a high-pressure mercury lamp and a red-emitting rare earth phosphor (yttrium oxide phosphor).

Effects of the Invention By the method described above, the large ultraviolet radiation energy of a high-power discharge lamp is utilized for red light emission, which improves the energy efficiency of the lamp and also reduces the color shift due to the gradation of the blue component. Since the blue component is a bright line and there is no emission on the long wavelength side, there is no energy in the wavelength range from yellow to red that is transmitted through the color separation system or liquid crystal panel, making it possible to improve projection with good color reproduction. type display can be realized.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the light source optical system and color separation optical system of a liquid crystal projection display as an example of the present invention, and Fig. 2 shows a high-pressure mercury lamp and a red-emitting rare earth phosphor (yttrium oxide phosphor). FIG. I... High-pressure mercury lamp using quartz glass for the outer tube bulb, 2 -Φ condensing mirror, 3, 11Φ quartz lens optical system, 4Ie beam splitter, 5... Wavelength 62 Onm
A glass panel coated with a rare earth phosphor (yttrium O oxide phosphor) that has a sharp line spectrum in the vicinity, a first liquid crystal panel that produces an image with 6.0 red components, and 7... - a first projection lens. , 8@...Screen, 3...Dichroic mirror, 106.Second liquid crystal panel that creates a blue component image, 11Φ.Second projection lens, 12.Reflection mirror, 13.Fist filter.
14.Φ Third liquid crystal panel that creates an image of the green component,
+5-°3rd projection lens. Name of agent: Patent attorney Toshio Nakao

Claims (1)

[Claims] A light source that has bright line radiation near wavelengths of 450 nm and 550 nm and that emits radiation in the ultraviolet region with a wavelength of 300 nm or less is housed in a condensing optical system, and only the ultraviolet radiation component of the radiation emitted from the condensing optical system is separated to produce a red color. a red image projection optical system comprising a first projection lens that guides a panel coated with a light-emitting phosphor to emit light, makes the radiation incident on a liquid crystal panel for a red image, and projects the resulting red image on a screen; Of the radiation emitted from the condensing optical system, only the ultraviolet radiation component is separated and removed, and only the green component radiation is separated from the visible radiation and made incident on a liquid crystal panel for a green image, and the resulting green image is projected on a screen. a green image projection optical system comprising a second projection lens, and a blue component radiation from which the ultraviolet radiation component and the green component are separated and removed from the radiation emitted from the condensing optical system, and incident on a liquid crystal panel for a blue image. , a blue image projection optical system consisting of a third projection lens that projects the resulting blue image onto a screen, and a liquid crystal projection display consisting of the above three color image projection optical systems.