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. 16, 1989
Filed:
Sep. 26, 1986
Jeff L McClelland, Lowell, MA (US);
Shigesato Iwasa, Harvard, MA (US);
Neal R Butler, Acton, MA (US);
Honeywell Inc., Minneapolis, MN (US);
Abstract
What is disclosed is a preamplifier used with each pyroelectric detector in an infrared imaging array system. To bias the preamplifiers either a MOSFET transistor is utilized as a switch that is periodically operated to place charge on the gate of the MOSFET preamplifier transistor to maintain it at its bias level, or an NPN transistor is operated at a level to provide high impedance. When the bias switch is not operated, the associated detector detects and a reading is taken from each detector in the array. NPN transistor switches can be manufactured consistently and their conduction level can be adjusted to balance the gain of all preamplifiers in the detector array. The supply voltage to the preamplifiers in the array is monitored by a feedback circuit which compares a supply voltage to a reference voltage and adjusts the preamplifier bias voltage to compensate for changes in the supply voltage.