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:
Sep. 23, 2014
Filed:
Mar. 18, 2011
Applicants:
Akira Yamada, Tokyo, JP;
Yuuichi Kumazawa, Tokyo, JP;
Tomoya Nakata, Tokyo, JP;
Katsumi Morikawa, Tokyo, JP;
Inventors:
Akira Yamada, Tokyo, JP;
Yuuichi Kumazawa, Tokyo, JP;
Tomoya Nakata, Tokyo, JP;
Katsumi Morikawa, Tokyo, JP;
Assignee:
Azbil Corporation, Tokyo, JP;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G05B 11/01 (2006.01); G06F 1/14 (2006.01); G06F 11/16 (2006.01);
U.S. Cl.
CPC ...
G06F 11/1604 (2013.01); G06F 1/14 (2013.01); G06F 11/1608 (2013.01);
Abstract
An RTC, having a crystal oscillator of different characteristics from those of a crystal oscillator, is provided, and the pulse period of the pulse signal from the RTC and the pulse signal based on the crystal oscillator are compared to detect a fault in the crystal oscillator. As a result, even if, for example, located in a high temperature environment, the degrees to the decrease in frequency will be different, thus making it possible to detect reliably a fault in the crystal oscillator.