JP2856955B2 - Short arc type metal halide lamp light source device - Google Patents

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 provided with a short arc type metal halide lamp which is lit vertically.

[0002]

2. Description of the Related Art Metal halide lamps have a high light emission efficiency and are used for various purposes. Recently, however, they have attracted attention as backlights for liquid crystal projection televisions. In order to use it as a backlight of a liquid crystal projection television, it is necessary to use a short arc type having a distance between electrodes of about 3 to 7 mm and to obtain a substantially parallel radiated light in combination with a concave reflecting mirror. As a lighting state in combination with the concave reflecting mirror, there are known a lighting method of arranging horizontally and lighting, and a lighting method of vertically arranging and extracting light downward.

An example of a conventional light source device for a liquid crystal projection television in which a short arc type metal halide lamp is turned on vertically will be described with reference to FIG. As shown in this figure, the light source device comprises a short arc type metal halide lamp 1 and a concave reflecting mirror 6 arranged so as to take out the radiated light from this short arc type metal halide lamp 1 downward. The lamp 1 has a substantially spherical bulging portion 21 at the center of a bulb 2 made of quartz glass, and a sealing tube portion 24 pinched and sealed on both sides. A pair of electrodes 31 and 32 are disposed in the bulging portion 21 so as to face each other.
Is connected to a metal foil 4 embedded in the sealing tube portion 24, and an external lead 5 extending further outward is connected to the metal foil 4. A reflection film 7 made of opaque silica and alumina powder is formed below the bulging portion 21 for convenience as shown by a dotted line.

The reason for providing this reflection film 7 is that in the metal halide lamp, supersaturated metal 8 is deposited at the lower portion of the bulging portion 21 at room temperature, and since the lower portion is the coldest point of the metal halide lamp, the metal 8 Is difficult to evaporate. That is, by forming the reflective film 7, the infrared rays generated by the discharge are reflected, and the metal 8 is reflected.
Usually, the effect cannot be sufficiently exerted unless the lower electrode 32 is provided to such an extent that the lower electrode 32 is hidden.

In the vertical lighting, there are a method of extracting light downward and a method of extracting light upward depending on the positional relationship with the concave reflecting mirror. In this conventional example, light is extracted downward. The reason is to minimize the influence of the reflection film 7. That is, when light is extracted downward, the light kicked by the reflective film 7 is originally unused light, whereas when light is extracted upward, the light kicked by the reflective film 7 illuminates the central portion. This is because it is very important light.

[0006]

When light is extracted downward, tungsten, which is a substance scattering from the electrode, adheres to the upper side of the bulging portion 21 and blackens, or the bulging portion 21 is sealed due to convection. The object and the quartz glass tend to react with each other to cause devitrification, and as a result, there is a problem that the emission of light is hindered early and the service life of the lamp is short.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a reflective film for evaporating metal which is not necessary or only a little provided. An object of the present invention is to provide a short arc type metal halide lamp light source device which is less affected by blackening and devitrification.

[0008]

A short arc type metal halide lamp light source device according to the present invention comprises a short arc type metal halide lamp which is lit vertically, and a concave reflector arranged so as to reflect upward the radiation emitted from the lamp. The short arc type metal halide lamp is characterized in that the bulb shape surrounding the upper electrode is substantially spherical, and the bulb shape surrounding the lower electrode is substantially truncated cone.

[0009]

[Function] Since the shape of the lower bulb is a truncated cone, the distance between the metal accumulated on the lower side of the bulging portion and the lower electrode becomes shorter, and the metal is quickly heated and evaporated, so that the reflection film is formed. Need very little. As a result, the concave reflecting mirror can be arranged so as to reflect light upward, and even if the transmission of light is interrupted due to devitrification due to the adhesion of tungsten, which is an electrode scattering substance, or the reaction between the sealing substance and quartz glass, Since the blocked light is light that is hardly used, the lamp eventually has a long service life.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. FIG. 1 is an explanatory sectional view in which a short arc type metal halide lamp light source device according to the present invention is applied to a backlight of a liquid crystal projection type television. It is a concave reflecting mirror that reflects light.

The short arc type metal halide lamp 1 has a bulging portion 21 at the center of the bulb 2 and a pinch-sealed sealing tube portion 24 on both sides. In the central bulging portion 21, the upper A portion 22 has a substantially spherical shape, and the lower B portion 23 has a substantially truncated cone shape. A pair of electrodes 31 and 32 are opposed to each other in the central bulging portion 21, the upper electrode 31 is surrounded by a spherical A portion 22, and the lower electrode 32 is shaped like a truncated cone. Are surrounded by a B portion 23. These electrodes 31 and 32 are respectively connected to a pair of metal foils 24 embedded in the pinch seal portion 24, and external leads 5 extending further outward are connected to these metal foils 4.

The short arc type metal halide lamp 1 is filled with argon gas and a metal composed of mercury, dysprosium, and neodymium in the form of a halogen compound. The amount is enclosed.

When the short arc type metal halide lamp 1 is turned on, the metal 8 accumulated under the swelling portion 21 is rapidly heated by the lower electrode 32 to evaporate, and a stable lighting state is achieved. Transition. The time required for shifting to the stable lighting state is about 40 seconds, which is almost the same as the case where the conventional reflective film 7 is provided. Therefore, in the present invention, it is not necessary to provide the reflection film 7, or a small portion may be used as long as the reflection film 7 does not hinder the utilization of light. It can be.

If the electrode 31 is used for a long time,
Tungsten, which is a scattered substance from 32, adheres to the inner surface of the bulb of the upper spherical portion A, but the light in the adhered portion is originally unused light, and has little effect. In addition, in the present invention, the volume of the upper portion A 22 is increased by an amount corresponding to the truncated cone on the lower side in the present invention. Therefore, the inner surface area on the upper side is larger than before, and it takes time for the scattered tungsten to adhere to the side surface which affects the radiation of light used, and eventually, the service life due to blackening of the bulb is prolonged. Can be stretched.

[0015]

As described in detail above, the short arc type metal halide lamp light source device of the present invention can evaporate metal quickly without providing a reflective film, and therefore has a concave surface so as to extract light upward. The reflector can be arranged, and as a result, the lamp life due to blackening or devitrification of the bulb can be extended, so that a light source device with a long service life can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view for explaining a short arc type metal halide lamp light source device of the present invention.

FIG. 2 is a sectional view for explaining a conventional short arc type metal halide lamp light source device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Short arc type metal halide lamp 2 ... Bulb 21 ... Swelling part 22 ... Spherical part 23 ... Truncated cone part 24 ... Sealing tube part 31, 32 ... Electrode 4 ... Metal foil 5 ... External lead 6 ... Concave reflector 7 ... Reflective film 8 ... Metal

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int.Cl. ⁶ , DB name) B01J 61/32 H01J 61/86 H01J 61/88

Claims (1)

(57) [Claims] 1. A short arc type metal halide lamp which is vertically lit and a concave reflector which is arranged to reflect upwardly radiated light from the lamp, wherein the short arc type metal halide lamp has an upper electrode. Wherein the bulb shape surrounding the lower electrode is substantially spherical, and the bulb shape surrounding the lower electrode is substantially frusto-conical.