The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 06, 1984
Filed:
Mar. 12, 1982
Hiroshi Honma, Hino, JP;
Hochiki Kabushiki Kaisha, Tokyo, JP;
Abstract
A photoelectric smoke sensor wherein a photo diode having a junction capacitance of 100 pH or less is employed and a resistor having a high resistance value of the order of mega-ohms is connected in series with the photo diode to obtain a photo output through the resistor, so that the voltage of the photo output may be sufficient to be directly subjected to comparison by the comparator without high-gain amplification even if the driving current for a light emitting diode is reduced. This enables omission of a high-gain amplifier and accordingly enables omission of a shield case for the circuits of the sensor which has been required to eliminate noises. Further this photoelectric smoke sensor is arranged so that the light emitting diode is driven intermittently, the photo output is compared with a reference voltage in synchronism with the driving of the light emitting diode, and the output from the comparator is data-read in by flip-flops at the timing of the decay of the photo pulse, to reduce the current consumption and simplify the circuit formation.