Ushio Denki Kabushiki Kaisha

Takashi Ito

Yoshihiro Horikawa

Akihiko Sugitani

Hiroto Sato

Tatsushi Igarashi

Mitsuo Narita

A high pressure mercury lamp in which formation and spreading of milky opacification in the fused silica glass forming the discharge vessel can be advantageously prevented, and thus a rapid decrease of screen illuminance prevented, when it is used as the light source of a liquid crystal projector and the like by, in a high pressure mercury lamp in which a discharge vessel of fused silica glass contains a pair of opposed tungsten electrodes, mercury in an amount that is at least equal to 0.16 mg/mm,, rare gas, and at least one halogen, and in which the wall load is at least equal to 0.8 W/mm,, the amount of mercury added being fixed in a range from 2&times;10,to 7&times;10,&mgr;mole/mm,, and/or the at least one halogen being in the form of a carbonless halogen compound, and/or the average OH radical concentration in an area of a wall of the discharge vessel at a depth of 0.2 mm from an inner surface of the wall of the discharge vessel being at most 20 ppm.

High pressure lamp with specific amount of mercury, halogen and wall loading

A high pressure mercury lamp with an extremely high mercury vapor pressure and extremely high tube wall load in which the arc during operation is advantageously stabilized is achieved in a high pressure mercury lamp having a discharge vessel of fused silica glass which contains a pair of opposed tungsten electrodes, mercury in an amount at least equal to 0.16 mg/mm.sup.3 and a rare gas, and in which the discharge tube has a tube wall load at least equal to 0.8 W/mm.sup.2, by at least one metal halide with a metal having an ionization potential that is at most 0.87 times as high as the mercury ionization potential being added to the discharge tube in a range of from 2.times.10.sup.-4 to 7.times.10.sup.-2 .mu.mole/mm.sup.3.

High pressure mercury lamp

A metal halide lamp with a distance of less than 3.0 mm between the electrodes, in which in the hermetically sealed portion no cracks occur, which can be produced without difficulty, and which enables advantageous operation is achieved with a halide lamp in which an arc tube made of quartz glass contains a cathode and an anode spaced from each other at a distance of less than or equal to 2.9 mm together with mercury and metal halides, and which is operated with a nominal wattage range of from 100 to 400 W using direct current, by causing the ratio D/H to be greater than or equal to 1.9 when D is the maximum inside diameter in millimeters in a direction which orthogonally intersects the axial direction of the electrodes in the discharge space and H is the length of the cathode projecting within the discharge space, also in millimeters.

Growing community of inventors

Tatsuno, Japan

Takashi Ito