Patent ID: 7443100
Filing Date: 2008-10-28
Classification: H01J

Abstract:
1. A mercury-free arc tube for a discharge lamp device, comprising: a closed glass bulb disposed in a middle of a glass tube, wherein a starting rare gas and a light emitting substance are enclosed in the closed glass bulb; a tungsten electrode rod sealingly attached to a pinch seal portion disposed in an end of the glass tube, wherein a tip end portion of the electrode rod projects in the closed glass bulb; and a residual compression strain layer formed in a contact face between a glass layer in the pinch seal portion and the electrode rod, wherein the residual compression strain layer surrounds the electrode rod, wherein the electrode rod has a diameter of 0.3 mm or more, and the residual compression strain layer has a radius R≦D/4 about the electrode rod with respect to a width D of the pinch seal portion, the width D of the pinch seal portion is in a direction that is perpendicular to a longitudinal direction of the arc tube.