Ultrahigh pressure mercury lamp

Abstract

An ultrahigh pressure mercury lamp which is small and has high light radiation intensity and moreover good color reproduction with high efficiency in which, even with a large amount of mercury added, a failure of the mercury to vaporize in the bulb part does not occur, and in which blackening of the bulb part due to wearing of the electrodes even under a large electrode load as a result of shortening of the distance between the electrodes is low is obtained by an ultrahigh pressure mercury lamp in which a bulb part of the discharge vessel made of translucent material has an essentially ovoid shape, is filled with at least 0.2 mg / mm<3> of mercury and which is operated at an input wattage of at most 400 W using direct current, has the length D mm of the tip area of the anode and the length L mm of the bulb part in the direction of the tube axis of the lamp set in accordance with the relationship D>=L / 2.

Description

technical field [0001] The invention relates to an ultra-high pressure mercury lamp, in particular to an ultra-high pressure mercury lamp used as a light source for liquid crystal projectors and other projection-type projection devices. Background technique [0002] A light source used in liquid crystal projectors etc. projects light in one direction through a reflector, and then irradiates it onto the screen through an optical system such as a lens. The ideal case for this light source is a point light source. However, it actually has a certain size determined between electrodes of a lamp as a light source. If the size of the light source is approximately regarded as a point light source, it can be considered that such a lamp is ideal. The lamp tube part of the lamp is a spherical body with uniform wall thickness, and the center of the arc formed by the discharge in the lamp tube will Arranged in the center of the tube part. [0003] However, in the case of, for example,...

AI Technical Summary

Problems solved by technology

However, if the amount of mercury sealed in the existing lamp is increased to 0.2mg / mm 3 Above, even if the arc position in the discharge vessel is shifted to the cathode side, the problem of non-evaporated mercury will occur in other parts such as the root of the anode.

When the unevaporated mercury coagulates and the mercury particles reach a certain size of about 0.2mm or more, there will be such a problem that the mercury will move to the largest inner diameter due to gravity, and then condense the mercury again at the anode root of the evaporation source. cycle, the convection in the lamp changes and as a result the arc becomes unstable and flicker occurs

In addition, if the distance between the electrodes is shortened to obtain a high radiation intensity, there is a problem that the heat flowing into the electrodes increases, especially the loss of the anode is increased, and the service life of the lamp itself is shortened.

On the other hand, in order to suppress the thermal influence on the anode, it is conceivable to increase the volume of the anode itself, but there is such a problem that if the diameter of the anode portion is increased, the diameter of the lamp tube portion will also become larger, which cannot be achieved. meet the miniaturization requirements of the lamp

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