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:
Jul. 26, 1983
Filed:
Jan. 19, 1981
Paul N Ramsden, Leamington Spa, GB;
Michael H Groves, Warwick, GB;
Stanley Tools Limited, Woodside, GB;
Abstract
A measuring rule has a coilable steel measuring blade extensible through an opening in a housing and is marked along its length with regularly spaced dark areas separated by light areas. Two pairs of light sensors are located near the rule each associated with a light emitter. Each sensor is 180.degree. out of phase with the other sensor of the pair and 90.degree. out of phase with the other two sensors. The outputs of each pair of sensors are used to produce a difference signal. The difference signals are used by a counter to measure the magnitude and direction of movement of the blade. Each sensor output signal is divided by voltage divider to give a divided signal and each sensor output signal is compared with the complementary divided signal at the instant the difference signal of the other pair of sensors changes state and a fault signal is generated if its minimum is larger than the maximum of the complementary divided signal. The fault signal is generated when an abnormal deviation in a sensor output signal occurs even if the deviation is insufficient to cause a count error.