JPH087841A - Metal halide lamp with reflecting mirror - Google Patents

Abstract

PURPOSE:To cut off the influence of the ambient atmosphere, and to suppress the variation of the electric property and the luminous property in the lamp lighting condition, by providing a translucent front plate on which a membrane to reflect the ultraviolet-rays and the infrared-rays is formed, at the opening of a reflecting mirror. CONSTITUTION:A reflecting mirror 9 has the form of a paraboloid or an ellipsoid with the opening diameter 100mm, for example, and a multilayer interference membrane 11 to permeate the infrared-rays is evaporation diposited on the reflecting surface at the inner surface. And a glass plate 12 made of a hard glass which is a translucent front plate is fixed to the opening 9b of the reflecting mirror 9 by a low melting point glass 13. On the glass plate 12, an ultraviolet-ray and infrared-ray reflecting membrane 14 which consists of a multilayer interference membrane made by laminating a titanium oxide and a silicon oxide alternatively is formed. When a metal halide lamp with reflecting mirror is assembled to a liquid crystal video projector, and it is lighted by a rating power, the lamp cuts off the air flow to cool a luminous tuve 1 by the glass plate 12, and a stable electric property and luminous property in the lighting condition 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 metal halide lamp with a reflecting mirror for a liquid crystal projector, a slide projector or the like.

[0002]

2. Description of the Related Art A metal halide lamp utilizes a phenomenon in which a metal halide enclosed in an arc tube evaporates while the lamp is lit, and metal atoms are excited to emit light in a high temperature arc. Therefore, it is possible to obtain a metal halide lamp with high efficiency and high color rendering in any light color by selecting the metal halide to be enclosed. Also, by shortening the distance between electrodes, so-called short arc, it is possible to approach the point light source, by incorporating this short arc metal halide lamp in the reflector,
A light source with high light collection efficiency can be obtained.

Due to these features, in recent years, a short arc type metal halide lamp with a reflecting mirror incorporated in a reflecting mirror is often used as a backlight source of a projection type liquid crystal video projector.

[0004]

However, since the metal halide lamp with a reflecting mirror used in such a liquid crystal video projector is required to be compact, a single-tube metal halide lamp without an outer tube is generally used. Used for. The single tube type metal halide lamp is easily affected by the ambient atmosphere, for example, the convection of air, and there is a problem that the electric characteristics and the light emission characteristics of the lamp are changed by the influence of the convection of the air. In addition, the short arc type metal halide lamp is
Since the internal pressure of the arc tube reaches several tens of atmospheric pressure during lighting, the arc tube may be damaged during the life of lighting. At this time, there is a risk that hot debris will be scattered around and the liquid crystal video projector body will be damaged. Also, a large amount of ultraviolet rays and infrared rays are emitted from the arc tube of the metal halide lamp. Since these ultraviolet rays and infrared rays are projected on the front surface by a reflecting mirror and deteriorate the optical components of the projection optical path, it is necessary to provide an ultraviolet and infrared cut filter in the projection optical path.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a metal halide lamp with a reflecting mirror which can reduce variations in electric characteristics and light emitting characteristics during lamp lighting and which does not deteriorate optical components in a projection optical path.

[0006]

A metal halide lamp with a reflecting mirror according to the present invention has a reflecting mirror and an arc tube provided inside the reflecting mirror, and ultraviolet and infrared rays are provided in the opening of the reflecting mirror. It has a configuration in which a translucent front plate on which a film that reflects light is formed is provided.

[0007]

With this structure, the influence of the surrounding atmosphere can be cut off, and fluctuations in electrical characteristics and light emission characteristics during lamp lighting can be reduced. Further, it is possible to attenuate the radiant intensity of ultraviolet rays and infrared rays in the projected light and prevent the fragments from scattering around even if the arc tube is damaged during the life of lighting.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a rated power 1 according to an embodiment of the present invention.
A metal halide lamp with a 50 W reflector is shown.

As shown in FIG. 1, a pair of electrodes 2a made of tungsten are provided inside an arc tube 1 made of quartz glass.
2b is provided, and the distance between the electrodes is 4 mm in order to approach the point light source. The arc tube 1 is filled with a predetermined amount of mercury, dysprosium iodide, neodymium iodide, and cesium iodide as an argon gas as a starting gas. Sealing portions 3a and 3b are provided at both ends of the arc tube 1, and metal foils 4a and 4b made of molybdenum connected to the electrodes 2a and 2b are hermetically sealed to the sealing portions 3a and 3b. . The metal foils 4a and 4b have external conductors 5a,
One end of 5b is connected, and the other ends of the external conductors 5a and 5b are led out of the arc tube 1. Lead wires 6 and 7 are connected to the external lead wires 5a and 5b led out to the outside, respectively. The ceramic base insulator 8 provided in the sealing portion 3b is inserted into the hole of the bottom portion 9a of the reflecting mirror 9 made of hard glass so that the central axis of the arc tube 1 and the central axis of the reflecting mirror 9 coincide with each other. It is fixed to the hole by cement 10. The reflecting mirror 9 has a parabolic or elliptical shape with an opening diameter of 100 mm, and a multilayer interference film 11 that transmits infrared rays is deposited on the inner reflecting surface. The glass plate 12 made of hard glass, which is a translucent front plate, is fixed to the opening 9b of the reflecting mirror 9 by the low melting point glass 13. On the glass plate 12, an ultraviolet / infrared reflecting film 14 made of a multilayer interference film in which titanium oxide (TiO ₂ ) and silicon oxide (SiO ₂ ) are alternately laminated is formed. The glass plate 12 has a thickness of 3 mm, and a through hole for allowing the external conductor 5a to pass through is provided in the central portion. Further, the heat insulating film is not provided at the end of the arc tube.

The metal halide lamp with a reflecting mirror of this embodiment is incorporated in a liquid crystal video projector, and the rated power is 1
When the lamp was turned on at 50 W, it was confirmed that the glass plate 12 could block the flow of the air for cooling the arc tube 1, and the lamp could obtain stable electric characteristics and light emitting characteristics during lighting. It was also confirmed that the ultraviolet / infrared reflecting film 14 formed on the glass plate 12 can suppress the radiation intensity of ultraviolet rays and infrared rays by 99% as compared with the conventional lamp.

Further, when the metal halide lamp with a reflector of this embodiment is overloaded and the arc tube is forcibly damaged, fragments of the arc tube are prevented from scattering by the glass plate 12 to the outside of the mirror. It was confirmed that damage to the LCD video projector body could be prevented.

The evaluation optical system shown in FIG. 2 has basically the same structure as the liquid crystal video projector body, and includes a condenser lens 15 and an aperture 1 corresponding to a liquid crystal panel.
6 (diagonal length 2.8 inches), a projection lens 17 and a screen 18 (diagonal length 40 inches).

When a conventional metal halide lamp with a reflector having a heat insulating film made of zirconia applied to the outer surface of the end of the arc tube is projected on the screen 18 at a rated power of 150 W using the evaluation optical system, the screen center illuminance is 1
It was 3000 lux. Similarly, when the reflector-equipped metal halide lamp of the present embodiment is projected onto the screen 18 at a rated power of 150 W by the evaluation optical system, the screen center illuminance is 14500 lux, and the reflector-equipped metal halide lamp of the present embodiment is: It was confirmed that the amount of projected light increased compared to the conventional metal halide lamp. This is because the conventional lamp has a heat insulating film made of a metal oxide formed on the outer surface of the end of the arc tube 1. Therefore, the heat insulating film blocks the light emitted from the arc tube 1 in the visible region, and the arc tube 1 In contrast to the fact that the light emitted from the lamp was not effectively used, in the present embodiment, the ultraviolet / infrared reflecting film 14 formed on the glass plate 12 radiates the light from the arc tube 1 without forming the heat insulating film. The generated infrared rays return to the arc tube 1 itself, the arc tube 1 is sufficiently kept warm, and the vapor pressure of the metal halide in the arc tube 1 can be sufficiently obtained, so that this heat retaining film can be dispensed with. As a result, the light emitted from the arc tube 1 can be fully utilized.

[0015]

As described above, the metal halide lamp with a reflecting mirror of the present invention has the reflecting mirror and the arc tube provided inside the reflecting mirror, and the ultraviolet ray is provided in the opening of the reflecting mirror. By providing a translucent front plate with a film that reflects infrared rays and infrared rays, it is possible to block the influence of the surrounding atmosphere and suppress variations in electrical characteristics and light emission characteristics during lamp lighting. Since the radiant intensity of ultraviolet rays and infrared rays in the light can be attenuated, deterioration of optical components in the projection optical path can be prevented. Even if the arc tube is damaged during lighting, there is no risk of damaging the liquid crystal video projector body, as the fragments generated by it are prevented from scattering outside the reflecting mirror by the translucent front plate. . Furthermore, since it is not necessary to form a heat insulating film on the outer surface of the end of the arc tube, it is possible to use the light emitted in the visible region from the end of the arc tube.
It is possible to increase the efficiency of collecting the light emitted from the arc tube and increase the amount of projected light.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view of a metal halide lamp with a reflector according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of an evaluation optical system.

[Explanation of symbols]

 1 Arc Tube 9 Reflector 11 Multilayer Interference Film 12 Glass Plate 14 Ultraviolet / Infrared Reflective Film

Claims (2)

[Claims] 1. A translucent front plate having a reflecting mirror and an arc tube provided inside the reflecting mirror, and having a film for reflecting ultraviolet rays and infrared rays formed in an opening of the reflecting mirror. A metal halide lamp with a reflector that is provided. 2. The metal halide lamp with a reflecting mirror according to claim 1, wherein a heat insulating film is not formed on the outer surface of the end portion of the arc tube.