Patent ID: 6271758
Filing Date: 2001-08-07
Classification: G08B

Abstract:
A light projection device for a photoelectric smoke sensor in which beam light is emitted into a monitored space and a fire is detected by receiving a beam light which is attenuated by smoke entering the monitored space, whereinsaid light projection device comprises a light emitting diode and a condenser lens which are arranged in an optical axis direction, and wherein,said light emitting diode comprises:a main unit base;a cylindrical cover which is attached to one side of said main unit base and to the tip end of which a lens is integrally disposed;a light emitting chip which is placed at a predetermined position inside said cover;a bonding wire through which a lead wire passing through said main unit base is electrically connected with said light emitting chip; anda reflector which is placed behind said light emitting chip, andsaid light emitting chip is a first light source; and a position where light, which is forward reflected by said reflector, is projected through said lens of said cover is a virtual second light source,wherein a focal point of said condenser lens is located between said first light source and said second light source.