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:
May. 02, 1978
Filed:
Jul. 08, 1976
Frans Brouwer, Glencoe, IL (US);
Conrac Corporation, New York, NY (US);
Abstract
A particulate products of combustion detector having a light emitting diode and a photovoltaic solar cell coupled one to the other to serve as a particulate or smoke sensor. A free-running multivibrator periodically pulses the light emitting diode to corresponding pulses of light emission having a first pulse-repetition frequency of about 80 Hz. and a duty cycle of about five percent. The output of the solar cell is connected to the input of a ringing amplifier to generate at the amplifier output a ringing pulse sequence having the same pulse-repetition frequency as that of the light element emissions in response to the detection of the particulate products of combustion. The ringing amplifier has a passband of about 500 Hz. centered about a frequency of about 1000 Hz. A detector is connected to the output of the ringing amplifier to generate a peak voltage responsive and proportional to the greatest voltage amplitude of each ringing pulse, namely, that of the first half-cycle of each ringing pulse. A bistable flip-flop is connected to the output of the peak voltage detector. When a peak voltage greater than a threshold magnitude is applied to the flip-flop indicative of the detection of the products of combustion, the circuit is driven to its second stable state, thereby actuating a smoke alarm relay.