US 6,271,758 B1Granted

Light projection device for a photoelectric smoke sensor

AssigneeHochiki Corporation

InventorsMasatoshi Nakamura, Hiroshi Shima, Hidenari Matsukuma

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Abstract

A light emitting diode 1 and a condenser lens 2 are arranged in an optical axis direction. In the light emitting diode 1, a cover 4 having a tip end lens 5 is attached to one side of a main unit base 9, a light emitting chip 6 is supported by a bonding wire 8 drawn out from the body base 9 inside the cover 4, and a reflector 7 is placed behind the light emitting chip 6. With respect to a first light source of the light emitting chip 6, the position where light which is forward reflected by the reflector 7 impinges on the tip end lens 5 is set as a virtual second light source 10, and the focal point of the condenser lens 2 is set at the position of or in the vicinity of the position of the second light source 10.

Claims7

Dependent claims

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, wherein

said 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;
and
a reflector which is placed behind said light emitting chip, and
said 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.

8 more elements

Dependencies are inferred from the claim text.