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. 16, 1991
Filed:
May. 26, 1989
John A Skinner, Hampshire, GB;
De La Rue Systems, Ltd., , GB;
Abstract
Apparatus for sensing the passage of sheets (1) through a nip formed by rollers (5 and 6), includes a core (14), moving with the shaft of one of the rollers, and a flat coil (15) connected to an oscillator circuit for sensing the deflection of one roller relative to the other. The oscillator circuit (18) provides a train of signals the frequency of which varies with the amount of the relative deflection of the rollers, and a counter (19) counts the signals from the oscillator in a fixed time interval. A store (22) stores counts representing the relative deflections of the rollers in a cycle of movement of the rollers when no sheet is present. The difference between a subsequent count and a stored count for a corresponding position in the cycle of rotation of the rollers is compared with a predetermined threshold, to establish the presence or absence of a sheet between the rollers.