Title: Low noise photoelectric detector apparatus

Abstract: A photoelectric sensor includes a photodetector, a lens, and a light source all mounted within a framework for holding the lens with the photodetector and light source located on the central axis of the lens. The photodetector is positioned on the rear side of the lens within the framework at approximately the lens focal point. The light source is positioned to emit light away from the front side of the lens. Structure in the form of an opaque collar is provided for mounting the light source relative to the lens to prevent impingement of spurious light from the light source upon the lens. An object positioned in front of the lens intercepts the emitted light from the light source and reflects it back toward the lens, whereupon it is directed to the photodetector. A signal indicative of the presence of the object is provided by the photodetector responsive to the reflected light.

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Inventors: Lazzara, Anthony Ross (Portola Valley, CA, US)

Application Number: 611871
Filing Date: 1975-09-10
Publication_date: 1976-12-07
Assignee: Scientific Technology Incorporated (Mountain View, CA)
Primary Class(es): 250/559.4 250/221, 250/227.11, 250/227.28, 250/552, 250/553, 250/574
Other Classes:
US Patent Ref:

3555532	Jan, 1971	White et al.	250/574.
3561846	Feb, 1971	Kingsland	250/566.
3819938	Jun, 1974	Kornrumpf et al.	250/553.
3892974	Jul, 1975	Elletson et al.	250/568.

Other Refs:
Primary Examiner: Smith, Alfred E.
Assistant Examiner: Moore, David K.
Attorney: