High-pressure discharge lamp, illuminator, automobile headlamp and luminotron for high-pressure discharge lamp

Abstract

A high pressure discharge lamp used as a pseudo point source can facilitate design capable of improving converging efficiency of a projection beam into a focus. A high pressure discharge lamp 1A has a light emitting vessel 2A made of a semitransparent ceramic material and having a pair of end portions 2a each with an opening formed in the end portion and a light emitting portion 2a, a pair of discharge electrodes 5, and electrode supporting members 4 each supporting the electrode 5 and fixed to the end portion 2a. The vessel 2A defines an inner space 6 with an ionizable light emitting substance and starter gas filled in the inner space 6. The electrodes 5 are contained in the inner space 6. The light emitting portion 2b has a thicker portion 2g and a thinner portion 2c. The thinner portion 2c has a cross sectional area of not smaller than 35 percent and not larger than 80 percent of that of the thicker portion 2g so that the light emitting portion 2b has a brightness center 9 in the thinner portion 2c.

Description

technical field [0001] The present invention relates to high pressure discharge lamps suitable for use in automobile headlights and the like. Background technique [0002] As headlamps for automobiles, high-pressure discharge lamps using quartz generator tubes are widely used because of their high brightness and high luminous efficiency. In the discharge lamp using such a quartz tube, since the discharge tube is transparent, the light-emitting portion formed by the luminescent gas in the discharge tube can be directly used as a point light source of the discharge lamp. [0003] In the automotive headlamp disclosed in Japanese Unexamined Patent Publication No. 5-74204, the discharge vacuum tube is housed in a container for shielding ultraviolet rays, and the light emitted from the discharge vacuum tube is reflected and projected by a reflector. In the discharge lamp headlamp described in JP-A-5-8684, it is disclosed that a metal halide lamp and a high-pressure sodium lamp ar...

AI Technical Summary

Problems solved by technology

[0006] However, when the luminous tube of a high-pressure discharge lamp is used as a simulated point light source, it is known in reality that the positional relationship between the luminous tube and the reflector is changed to change the converging position of the projected beam according to different lighting modes, and It is difficult to make the focal point of the projected beam coincide with each condensing position efficiently in terms of design

[0007] That is, since the luminous tube has a certain size, for example, even if the luminous tube and the reflecting plate are almost completely overlapped in the walking mode, and the focal point coincides with the light-gathering position, but in the passing mode, when the reflecting plate is changed, the projected It is very difficult to design the focal point of the beam to the converging position exactly

To solve this problem, it is effective to reduce the size of the luminous tube, but if the luminous tube is further miniaturized, it will be difficult to manufacture and the manufacturing cost will also increase.

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