Patent ID: 7070312

Claim:
A lamp unit, in a vehicle headlamp, for forming a linear portion of a cut-off line at an upper end of a light distribution pattern, the lamp unit comprising: a light source formed from a semiconductor light-emitting element having a light-emitting chip whose one side extends linearly; and a translucent member disposed so as to allow entry of light originating from said light source, wherein: said one side of said light emitting chip crosses an optical axis of said lamp unit at right angles; said one side of said light-emitting chip is aligned at a lower end section of said light-emitting chip; said translucent member is configured so as to subject incident light emitted from said light source to be reflected on a front surface of said translucent member and then reflected on a rear surface of said translucent member to exit from said front surface of said translucent member; a front surface of said translucent member is formed from a plane orthogonal to said optical axis; a rear surface of said translucent member comprises a light reflection control surface formed using a reference surface defined by a paraboloid of rotation whose focal point is a position having symmetry with an illumination center of said light source with reference to said front surface of said translucent member; and an area of said front surface of said translucent member located in the vicinity of said optical axis is subjected to mirror surface treatment, and a rear surface of said translucent member is subjected to mirror surface treatment.