Patent ID: 8217576
Filing Date: 2012-07-10
Classification: H01J

Abstract:
1. A high pressure discharge lamp comprising: a discharge vessel having a light emitting part and sealing parts connected to both ends of said light emitting part; and electrodes comprising electrode rods and electrode tip end parts arranged oppositely to each other in the light emitting part, said electrode rods being embedded in a respective one of said sealing parts, and axially directed grooves being formed in at least part of the surface of said electrode rods, wherein said electrode rods have an ungrooved rear end part where no grooves are formed, said ungrooved rear end part being located rearward in an axial direction relative to the part in which said grooves are formed, wherein a portion of the part of said electrode rods in which said grooves are formed is embedded in the respective sealing part along with said ungrooved rear end part, and wherein a diameter measured at groove bottom parts of the grooves of said electrode rods is larger than a diameter of the ungrooved rear end part where no grooves are formed.