Title: Photoelectric controlling

Abstract: A light source, such as a light emitting diode (LED), illuminates a cadmium sulfide or cadmium selenide photocell to lower its resistance and thereby initiate conduction in a solid-state device, such as a silicon controlled rectifier (SCR), to deliver current to a load that is interrupted by removing the light energy and restoring the photocell to its unilluminated high resistance state. A feature of the invention resides in limiting the optical energy incident upon the photocell so that its resistance remains well above the lowest resistance it can attain while still dropping to a resistance value considerably below its maximum resistance when unilluminated so that within the total resistance changes of the photocell, the small percentage resistance charge required for proper activation of the solid-state device, may be effected relatively rapidly both for turn on and turn off.

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Inventors: Rodriguez, Edward T. (Reading, MA, US)

Application Number: 599710
Filing Date: 1975-07-28
Publication_date: 1976-12-07
Assignee:
Primary Class(es): 250/551 250/214LS, 307/117, 327/109, 327/456
Other Classes:
US Patent Ref:

3476941	Nov, 1969	Bonin	250/211.
3524986	Aug, 1970	Harnde, Jr.	307/278.
3693060	Sep, 1972	Joyce	307/278.
3708672	Jan, 1973	Marinkovic	250/551.
3866051	Feb, 1975	Shearer et al.	307/315.

Other Refs:
Primary Examiner: Smith, Alfred E.
Assistant Examiner: Grigsby, T. N.
Attorney: Cohen; Jerry, Hieken; Charles