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:
Jul. 20, 1976
Filed:
Oct. 17, 1974
Jerome Peter Friedrichs, Des Plaines, IL (US);
Motorola, Inc., Schaumburg, IL (US);
Abstract
An oven having a thermistor controlled proportional heating system is compensated for ambient temperature variations by using a second thermistor sensing ambient temperature and connected in series with the control thermistor in an electrical bridge circuit. The control thermistor is mounted within the oven and substantially monitors the oven temperature while the ambient thermistor is located outside the oven and monitors ambient temperature. The electrical bridge circuit produces a temperature control error signal which is amplified and applied to a heater winding which is wrapped around the oven. The ambient thermistor produces a resistance variation in the electrical bridge circuit which modifies the temperature control signal such that a predetermined point inside the oven is held at a constant temperature regardless of any ambient temperature changes.