JPH0574418A - Light source device for projection type liquid crystal television - Google Patents

Abstract

PURPOSE:To provide a light source device, for which a metal halide lamp is used for a projection type liquid crystal television, and with which a utilization factor of effective light beam in a visible region is improved and an unnecessary heat ray is cut. CONSTITUTION:A low refractive index dielectric film 4 and a high refractive index dielectric film 5 are alternately formed on the surface mirror of a spherical emission tube 1 and on a semi-spherical side on the reverse side, and a multilayered film 3 is formed thereby, which reflects the light 7 in a near infrared region to the inside of the emission tube 1, and which emits the light 6 in a visible region to the outside of the emission tube 1. A utilization factor of light is improved by warming the emission tube by covering it with the multilayered film, which transmits the light beam in the visible region, and which reflects a heat ray.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light source device used in a projection type liquid crystal television which illuminates an image of a transmissive liquid crystal panel from the back by a metal halide lamp which is a light source and enlarges and projects it by a projection lens. ..

[0002]

2. Description of the Related Art In recent years, a projection type liquid crystal television, which illuminates an image on a transmissive liquid crystal panel from the back side by a light source lamp and enlarges and projects it by a projection lens, has been attracting attention.

As the light source lamp, a metal halide lamp is generally used because of its good color rendering and more than twice the luminous efficiency of a halogen lamp. The spectral characteristics of metal halide lamps are determined by the so-called halogen cycle, in which the vapor pressure of the metal iodide enclosed in the arc tube becomes sufficiently high and it is excited by the arc of mercury to separate into metal and iodine, which causes continuous light emission by the metal. To be done.
When the arc tube is lit in a vertical arrangement, the internal temperature distribution is 150 ° C or higher due to the effect of convection, and the heat-resistant temperature of the quartz glass forming the arc tube is 950 ° C, and the vapor of iodide is sufficient for continuous light emission. The coldest spot temperature 850 ℃ for applying pressure
It is difficult to satisfy both of them at the same time.

Therefore, for example, as shown in (FIG. 3),
The surface load of the bulb part 13 of the arc tube is suppressed so that the temperature of the high part 12 of the arc tube 11 becomes 950 ° C. or less,
By forming a heat insulating film 14 such as zirconia in the portion 13 of the arc tube having a relatively low temperature on the side opposite to the reflecting mirror, the coldest spot temperature is secured and the spectral characteristics by continuous light emission are obtained.

[0005]

As described above, the metal halide lamp is used as the light source lamp of the conventional projection type liquid crystal television, but it is sufficient if the cold spot temperature of the arc tube is low at the time of lighting. Since the continuous light emission is not obtained, the heat insulating film 14 such as zirconia is required.

Since the heat insulating film 14 is opaque, the utilization rate of the light emission 16 and 17 is reduced. Also, the heat insulation film 1
When 4 is made small, not only the heat retaining effect is not obtained, but also the light of the arc tube is directly emitted toward the device without being reflected by the reflecting mirror, so that the device is adversely affected by ultraviolet rays and heat rays.

In view of the above problems, the present invention is a transparent metal which transmits visible light to the surface of the arc tube of a metal halide lamp used in a light source device of a projection type liquid crystal television and reflects light having a wavelength longer than the near infrared region. By constructing a multilayer film,
A structure that improves the light utilization rate and reflects infrared rays to ensure an internal temperature and obtains continuous light emission. It also reflects visible light on the surface of the reflecting mirror and transmits light with a wavelength longer than the near infrared region. An object of the present invention is to provide a light source device characterized by preventing harmful heat rays from entering the liquid crystal panel by improving the light utilization rate and transmitting infrared rays by forming a multilayer film.

[0008]

A light source device for a projection type liquid crystal television according to the present invention comprises a low refraction dielectric film and a high refraction index in a hemispherical portion of a metal halide lamp used as a light source on a side opposite to a surface mirror of a spherical arc tube. By alternately forming dielectric films, light in the near infrared region is reflected inside the arc tube, and light in the visible region is radiated to the outside of the arc tube, forming a multilayer film. It is characterized by forming a multilayer film that reflects visible light and transmits light having a wavelength longer than the near infrared region.

[0009]

According to the light source device of the present invention, the reflecting mirror is formed with a multilayer film that reflects visible light on the surface and transmits light having a wavelength longer than the near-infrared region, thereby cutting heat rays harmful to the liquid crystal panel. In addition, the low-refractive-index dielectric film and the high-refractive-index dielectric film are alternately formed in the arc tube instead of the heat insulating film that does not transmit light rays, and the light in the near infrared region is reflected inside the arc tube. By constructing a multilayer film in which light in the visible region is radiated to the outside of the arc tube, a lamp light source with a high light utilization rate is realized.

[0010]

EXAMPLE An example of the present invention will be described below with reference to FIGS. 1 and 2. In the figure, a light source lamp (metal halide lamp) includes an arc tube 1 and a reflecting mirror 2. Low-refractive-index dielectric films 4 and high-refractive-index dielectric films 5 are alternately formed on the arc tube 1, light 6 in the near infrared region is reflected inside the arc tube, and light 7 in the visible region is emitted. The multilayer film 3 is radiated to the outside of the tube. The surface area of the arc tube spherical portion 8 is determined so that the high temperature portion 10 of the arc tube becomes 950 ° C. or lower, but the low temperature portion 9 on the opposite side becomes 850 ° C. or lower due to the influence of convection, etc. The required temperature cannot be maintained without the heat insulating film 14 as shown in 3). However, the conventional heat insulating film 14 reflects or absorbs not only the light beam 17 in the infrared region but also the light beam 16 in the visible region, so that the utilization efficiency of the light beam decreases. for that reason,
As shown in FIG. 2, the hemispherical multi-layered film 3 is formed on the spherical portion 8 of the arc tube 1, and the effective visible ray 6 among the rays emitted between the opposing electrodes 20 is transmitted as it is. , Harmful infrared light 7 that raises the temperature of the LCD panel
Is reflected to raise the temperature of the low temperature portion 9 to 850 ° C., sufficiently increase the vapor pressure of the metal iodide enclosed in the arc tube 1, and separate it into the metal and iodine excited by the arc of mercury. The continuous light emission in the visible region is made possible by smoothly performing the so-called halogen cycle in which continuous light emission by the metal occurs. Further, by forming a multilayer film 15 which reflects visible light 6 on the surface of the reflecting mirror 2 and transmits light 7 having a wavelength longer than the near infrared region, heat rays harmful to the liquid crystal panel can be cut.

[0011]

As described above, according to the light source device of the present invention, the infrared ray is not transmitted through the arc tube, so that the low temperature portion of the arc tube is kept warm and the heat ray causing the temperature rise of the liquid crystal panel is cut off. It is possible to improve the utilization rate of effective light by transmitting the light source in the region, and the reflective mirror reflects the visible light on the surface, and is a multilayer film that transmits light with a wavelength longer than the near infrared region, which is harmful to the liquid crystal panel. The heat rays can be cut.

[Brief description of drawings]

FIG. 1 is a sectional view of a light source device for a projection type liquid crystal television according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of an arc tube of a light source device for a projection type liquid crystal television according to an embodiment of the present invention.

FIG. 3 is a sectional view of a light source device for a projection type liquid crystal television of a conventional example.

[Explanation of symbols]

 1 Arc Tube 2 Reflector 3 Dielectric Multilayer Film 4 Low Refractive Index Dielectric Film 5 High Refractive Index Dielectric Film 6 Visible Rays 7 Infrared Rays 8 Arc Tube Spherical Portion 9 Arc Tube Low Temperature Area 10 Arc Tube High Temperature Area

Claims (1)

[Claims] 1. A reflecting mirror having a hole in the center and a multilayer film formed on the surface for transmitting rays in the infrared region and reflecting rays in the visible region, and one end fixed to the hole portion of the reflecting mirror. In a metal halide lamp composed of an arc tube and used as a light source for a projection type LCD TV, a low-refractive index dielectric film and a high-refractive index dielectric film are alternately formed on the hemispherical portion of the spherical arc tube opposite to the surface mirror. A light source device for a projection type liquid crystal television, characterized in that a multi-layer film in which light in the near infrared region is reflected inside the arc tube and light in the visible region is emitted outside the arc tube.