Patent ID: 8698411
Filing Date: 2014-04-15
Classification: H01J

Abstract:
1. A discharge lamp lighting apparatus comprising: a short arc type discharge lamp including an arc tube in which a pair of tungsten electrodes is arranged so as to face each other, each electrode comprising an electrode head portion which is formed at a tip of an electrode axis portion, a base end portion of the electrode axis portion is buried and held in a sealing portion of the arc tube, the electrode axis portion including a projection portion that projects into the arc tube; and a power supply unit, that supplies an alternating current to the discharge lamp, configured to supply the alternating current such that a relation of a natural frequency fe (Hz) of the electrodes in the arc tube, which is obtained by a formula (1) shown below, a ripple frequency fd (Hz) of the alternating current, and a ripple power Pr (W) of the alternating current, satisfies a formula (2) shown below: wherein the formula (1) is wherein, for a given electrode, an eigenvalue of bending vibration of a cantilever having a concentrated mass in the electrode is represented as “a”, a value obtained by multiplying 0.623 by a distance (mm) from a base end of the projection portion of the electrode axis portion to the center of gravity of the electrode head portion, is represented as “le”, a Young's modulus of the electrode is represented as “E”, a second moment of area of the electrode axis portion is represented as “I”, and a density of the electrode is represented as “p”, and a cross-sectional area of a cross-section of the electrode axis portion taken along a direction perpendicular to an axial direction is represented as “S”, wherein the formula (2) is wherein the volume (mm