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:
Jun. 27, 1989
Filed:
Dec. 30, 1987
Michael E Range, Lincoln Township, Berrien County, MI (US);
David P Langendonk, Coloma Township, Berrien County, MI (US);
Whirlpool Corporation, Benton Harbor, MI (US);
Abstract
A thermostat controlled circuit for a bias heater located adjacent the thermostat connected to a source of alternating electrical power. The control circuit has a manually operated switch for providing a temperature level signal. A triac having a gate terminal and first and second terminals connected in series with the AC power source and the bias heater is provided. A transistor circuit controls the operation of the triac and is connected to the gate of the triac to provide a signal for turning on the triac periodically. The microprocessor supplies an enable signal to the transistor circuit at predetermined time intervals to cause the transistor circuit to activate the triac. The triac turns off at the next zero crossing of the AC line current after the microprocessor has removed the enable signal from the transistor circuit. The point in time of turning on the triac may be synchronous or asynchronous with the AC line current. The bias heater supplies heat to a thermostat in the discharge duct of a clothes dryer which combines with heat supplied by air exiting the clothes dryer and controls the point in time at which the thermostat opens and closes.