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:
Jan. 24, 1989
Filed:
Jan. 19, 1988
Applicant:
Inventors:
Assignees:
Hitachi, Ltd., Tokyo, JP;
Hitachi Automotibe Engineering, Tokyo, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
G01M / ;
U.S. Cl.
CPC ...
73116 ; 324169 ;
Abstract
An engine rotation speed detecting apparatus comprises circuitry for sensing the state of operation of an engine, circuitry for setting a plurality of respectively different masking periods of time, circuitry for detecting an ignition signal lasting for a period of time longer than any one of the plural masking periods of time thereby detecting an ignition period defined between adjacent ignition signals, and circuitry for computing the rotation speed of the engine on the basis of the detected ignition period, one of the plural masking periods of time being selected according to the result of sensing by the operation state sensing circuitry.