Title: Photoelectric smoke detector with means for adjusting the amount of light projected into the detection region

Do you think this is a good invention? Vote now:

Votes so far: For:(0) Against:(0)
Claims: What is claimed is:

1. In a photoelectric smoke detector comprising a housing with an opening for admitting smoke thereinto, a light source and a light receiving element contained in said housing whereby when the smoke enters into a detection region in said housing the quantity of the light emanated from said light source and impinged upon said light receiving element is varied to produce an electric signal, the improvement comprising a light shielding member located in said detection region for preventing the light from said light source from impinging directly upon said light receiving element, and an adjusting screw movable along the top edge of said light shielding member for adjusting the quantity of the light projected into said detection region and the quantity of light impinging upon said light receiving element, said light receiving element receiving smoke scattered light from said light source.

2. The photoelectric smoke detector according to claim 1 wherein said adjusting screw is threaded into a threaded opening through said housing and provided with an opening at the upper end thereof for receiving an adjusting tool and wherein the upper end of said adjusting screw is covered by a sealing member for preventing the turning of said adjusting screw and for preventing the moisture in the ambient air from reaching said adjusting screw.

3. The photoelectric smoke detector according to claim 1 which further comprises a cover removally mounted on the lower end of said housing for defining a gap for admitting smoke into the housing between said housing and said cover, the lower end of said adjusting screw being exposed when said cover is removed and wherein the lower end of said adjusting screw is also provided with an opening for receiving an adjusting tool.

4. The photoelectric smoke detector according to claim 3 wherein said opening is formed inside the lower end of said adjusting screw so that the rotation thereof does not change the peripheral profile of said lower end.

Other info:

Inventors: Kajii, Shigeru (Kawasaki, JA)

Application Number: 567173
Filing Date: 1975-04-11
Publication_date: 1976-11-16
Assignee: Hochiki Corporation (Tokyo, JA)
Primary Class(es): 356/338 250/574, 340/630
Other Classes:
US Patent Ref:

3240109	Mar, 1966	Gran, Jr.	356/207.
3710365	Jan, 1973	Barnes	350/574.
3723747	Mar, 1973	Steele	356/207.
3868184	Feb, 1975	Marsocci	356/103.

Other Refs:
Primary Examiner: McGraw, Vincent P.
Assistant Examiner:
Attorney: Haseltine, Lake & Waters