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:
Aug. 20, 1991
Filed:
Dec. 20, 1990
Bruce R Long, Carlisle, PA (US);
Leslie C Hurley, Carlisle, PA (US);
William P Hanson, Carlisle, PA (US);
PPA Industries, Inc., Dallas, TX (US);
Abstract
A resonator heating element is attached to the surface of a crystal resonator. Resonator temperature sensing may be accomplished either by a sensor attached to the crystal enclosure, or through dual mode temperature sensing, or by both. A control system converts the sensed temperature into a series of variable-width pulses applied to the resonator heating element. Thus, the temperature sensing mechanism(s), control system and heating element comprise a temperature feedback control system which allows the crystal to stably operate at or very near its desired temperature. In an especially preferred embodiment, an integrated circuit from a switching power supply may be used in a novel manner to perform certain of the functions in the temperature feedback control loop. Plural resonators may be present in the enclosure, one of which may be directly involved in temperature sensing. In other embodiments, a ring-shaped insulative structure may additionally be disposed between the resonator and its enclosure.