Patent ID: 8659047

Claim:
A light emitting device comprising: a substrate having an element mounting area in a principal surface of said substrate, said substrate having a flat portion and a recess formed in said principal surface of said substrate, and said flat portion being adjacent to said recess; at least one light emitting element mounted in said element mounting area of said substrate, a heat radiation path extending through said substrate for release of heat emitted from said light emitting element, said heat radiation path having a thermal resistance that changes with a mounting position of said light emitting element; and a heat transfer member provided on said substrate and having a thermal conductivity different from a thermal conductivity of said substrate, said heat transfer member being configured to provide an uneven thermal resistance distribution in said element mounting area, wherein: said heat transfer member comprises a one-piece element and covers both of said flat portion and said recess; a thickness of said heat transfer member on the flat portion is less than a thickness of said heat transfer member in the recess; a top surface of said heat transfer member is flat in said element mounting area; said element mounting area has a size such that the light emitting element is mountable on any one of (i) said flat portion only, (ii) a border between the flat portion and the recess, and (iii) said recess only; and the mounting position of the light emitting element is determined based on at least one of (i) a relationship between a junction temperature and an emission brightness of said light emitting element and a relationship between the mounting position of said light emitting element and the junction temperature of said light emitting element, and (ii) a relationship between the junction temperature and the emission brightness of said light emitting element and a relationship between the mounting position of said light emitting element and the thermal resistance of said heat radiation path.