Ushio Denki Kabushiki Kaisha

Shoichi Terada

Minoru Fukuda

Kazuhiro Goto

Akihiko Sugitani

Kosuke Saka

Shigeyoshi Matsumoto

Tetsu Okamoto

Takahiro Toma

Keiichi Matsumoto

A discharge lamp lighting device includes a control unit adapted to control a frequency of the AC electric current supplied to a discharge lamp by a feeding unit, in different manners within a first term and a second term which are alternately repeated, the control unit is adapted to control the frequency of the AC electric current such that, within the first term, the frequency of the AC electric current becomes at least one frequency out of plural set frequencies, and is further adapted to control the frequency of the AC electric current, based on a predetermined frequency and an electric current within the previous first term, such that, within the second term, the frequency of the AC electric current becomes a frequency lower than this predetermined frequency.

Discharge lamp lighting device

A light source device which can also advantageously control the growth of the projection using the DMD type is achieved in a light source device which has an ultrahigh pressure discharge lamp) in which the silica glass discharge vessel is filled with greater than or equal to 0.15 mg/mmmercury and bromine; a feed device; an oval reflector; and a color wheel by the electrode on the side of the opening of the oval reflector of the discharge lamp having an increased diameter, and the relation 0.06&#x3c;W/I&#x3c;0.96 between the volume W (mm) of the tip area with increased diameter and the current value I being satisfied.

Light source device

An ultra-high pressure mercury lamp in which the tungsten comprising the electrodes is prevented from spraying during starting and operation, and blackening on the inside wall of the arc tube is prevented is achieved in that at least one of the electrodes has an axial part which is made essentially of tungsten and a starting part which is made essentially of tungsten, at least one of the axial part and of the starting part containing an electron emission material with a smaller work function than tungsten such that the value of S/A in mm/% by weight is in the range 1&#x2266;S/A&#x2266;1&#xd7;10, S in mmdesignating the surface area of the part of the electrode projecting into the arc tube containing the electron emission material and A in % by weight indicating the concentration of the electron emission material in this part.

Ultra-high pressure mercury lamp

Growing community of inventors

Himeji, Japan

Shoichi Terada