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. 20, 2014
Filed:
Jul. 30, 2012
Kazuo Akaike, Saitama, JP;
Tsukasa Kobata, Saitama, JP;
Tomoya Yorita, Saitama, JP;
Kaoru Kobayashi, Saitama, JP;
Kazuo Akaike, Saitama, JP;
Tsukasa Kobata, Saitama, JP;
Tomoya Yorita, Saitama, JP;
Kaoru Kobayashi, Saitama, JP;
Nihon Dempa Kogyo Co., Ltd., Tokyo, JP;
Abstract
An atmosphere temperature at which a quartz-crystal oscillator and an oscillation circuit are placed is controlled in high accuracy, and an output frequency with high stability is obtained. If oscillation outputs of first and second quartz-crystal oscillators are set to fand f, and oscillation frequencies of the oscillation outputs at a reference temperature are set to fand, respectively, {(f−f)/f}−{(f−f)/f} is calculated by a frequency difference detection unit. A digital value can be obtained by representing this value by 34-bit digital value, corresponding to a temperature. Therefore, this value is treated as a temperature detection value, a difference with a temperature set value is supplied to the loop filter, and the digital value therefrom is converted into a direct-current voltage to control a heater.