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:
Jun. 29, 1999
Filed:
Dec. 29, 1997
Abstract
An improved absolute position detection method is provided for a stroke sensing cylinder which includes a magnetic scale detecting step for obtaining a plurality of sine wave form voltages having different phases using a magnetic sensor unit in accordance with a driving operation of the cylinder. A wave form generation step is also provided for converting the sine wave form voltage obtained in the magnetic scale detection step into a square wave form and generating a triangle wave form having the same period as the thusly converted square wave form. A first absolute position value detection and stroke direction judging step is then provided for judging a first absolute position value and stroke direction of the cylinder using a pair of square and triangle wave forms generated in the wave form generation step. Lastly, a second absolute position value computation and storing step is provided for computing and storing a second absolute position value having a predetermined value based on the first absolute position value. The method of the present invention is directed to detecting a magnetic flux change of a magnetic scale using a plurality of magnetic sensors. The magnetic scale is disposed along the cylinder rod and includes at least one different magnetic scale processing period contained within a regularly protruded and recessed portion. Signal-processing is achieved using a microprocessor and a 1/N-dividing counter. The thusly signal-processed wave forms are counted and an absolute position and stroke direction is determined.