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:
Apr. 09, 1996
Filed:
May. 10, 1993
Keiji Hanzawa, Mito, JP;
Tetsuo Matsukura, Katsuta, JP;
Hirokazu Fujita, Kobe, JP;
Masayoshi Suzuki, Hitachiota, JP;
Masahiro Matsumoto, Hitachi, JP;
Hitachi, Ltd., Tokyo, JP;
Hitachi Automotive Engineering Co., Ltd., Ibaraki, JP;
Abstract
An apparatus for diagnosing the characteristic of an acceleration sensor and a method for diagnosis thereof are disclosed. The acceleration sensor includes a movable electrode (or mass part) displaced in accordance with an acceleration and a fixed electrode disposed opposite to the movable electrode. In a diagnosis mode, a signal for diagnosis is applied to the fixed electrode so that an electrostatic force as a force corresponding to a predetermined acceleration is generated between the fixed electrode and the movable electrode. In the case where the acceleration sensor is sound, the movable electrode or mass part is normally displaced. A failure of the acceleration sensor, the deterioration thereof in performance, a change in characteristic thereof caused from the lapse of time, or the like is self-diagnosed by detecting a change in capacitance between the movable electrode and the fixed electrode upon generation of the diagnosis signal. The force corresponding to the predetermined acceleration may be an electromagnetic force or a mechanical oscillation based on a piezoelectric element.