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. 24, 1977
Filed:
Nov. 19, 1975
Edward E Lafever, Hagerstown, IN (US);
Larry O Gray, Greensfork, IN (US);
Dana Corporation, Toledo, OH (US);
Abstract
An apparatus for detecting relative movement between two objects which is illustrated in the preferred embodiment as a vehicle road speed signal source including a reed switch oscillator for generating an output signal having a frequency and a magnitude proportional to the road speed of an associated vehicle. Current flows through a biasing coil proximate the reed switch to generate a magnetic field which is slightly less than the field required to close the switch contacts. A permanent magnet means attached to the drive shaft of the vehicle generates a magnetic field which aids the biasing coil magnetic field to close the reed switch contacts. A transistor responds to the closing of the reed switch contacts to turn off the current to the biasing coil which allows the reed switch contacts to open. The transistor responds to turn on the biasing coil current and the cycle is repeated to generate a pulsed signal as long as the magnetic field from the permanent magnet means is present once each revolution of the drive shaft. The oscillator pulsed output signal is shaped into a triangular output signal having one peak for each revolution of the drive shaft.