Patent ID: 7946733

Claim:
A discharge lamp comprising: a fixing base disposed on an end of the discharge lamp, the fixing base being insertable into a lamp holder which includes a reference surface and a rotating portion, the rotating portion being rotatable from a first position to a second position and having an insert portion at an inner periphery of the rotating portion, the fixing base including: a first substantially cylindrical body portion having a cylindrical portion, and further including first and second notches positioned at a distance from one another on a periphery of the first substantially cylindrical body portion, the first and second notches being portions of the first substantially cylindrical body portion which extend radially to a lesser distance than the cylindrical portion of the first substantially cylindrical body portion; a second substantially cylindrical body portion which is positioned axially relative to the first substantially cylindrical body portion and has a cylindrical portion, the second substantially cylindrical body portion having third and fourth notches serving as joint surfaces, the third and fourth notches being positioned a distance from one another on a periphery of the second substantially cylindrical body portion, the third and fourth notches being portions of the second substantially cylindrical body portion which extend radially to a lesser distance than the cylindrical portion of the second substantially cylindrical body portion; and a groove portion formed in between the first and second substantially cylindrical body portions, the groove portion having a base with a diameter which is equal to or less than the distance between the first and second notches, and the groove having a sidewall formed by the first substantially cylindrical body portion; wherein the distance between the first and second notches is equal to or less than the distance between the third and fourth notches; and the diameter of the first substantially cylindrical body portion is equal to or less than the diameter of the second substantially cylindrical body portion; and wherein when the third and fourth notches contact the insert portion and the fixing base rotates, the third and fourth notches rotate the rotating portion of the lamp holder, and the groove sidewall formed by the first substantially cylindrical body portion contacts the reference surface of the lamp holder to fix the fixing base to the lamp holder.