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PAPER PRESENCE AND SIZE DETECTOR

IP.com Disclosure Number: IPCOM000025021D
Original Publication Date: 1983-Apr-30
Included in the Prior Art Database: 2004-Apr-04
Document File: 2 page(s) / 75K

Publishing Venue

Xerox Disclosure Journal

Abstract

Methods of detecting the presence of paper commonly used are optical devices, switches and ultrasonic devices. Another type of sensor comprises a pinch roller, made either from a metal or conducting rubber, which bears on a metallic or second conducting rubber roller. In the absence of paper, the pinch roller is in contact with the fixed roller, and electrical continuity between the two shafts can be sensed. As shown in Figure 1, when paper is fed between the two rollers, the break in continuity may easily be detected and the presence of the paper sheet recognized.

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f

CONT l NU1 TY NO CONTINUITY

CONDUCTING RUBBER PINCH ROLLER PAPER PRESENCE DETECTOR

A= RESISTANCE OF I CONDUCTING RUBBER PINCH ROLLER RESISTANCE WITHOUT PAPER = Rl8
FOR RESISTANCE WITH PAPER R =
R/4 FIGURE ABOVE

FIG. 2

MULTIPLE CONDUCTING RUBBER PINCH ROLLER PAPER PRESENCE/WIDTH DETECTOR

CONDUCTIVE RUBBER ELECTRICAL

CONTACTS TO

ROLLERS PINCH SHAFTS

Volume 8 Number 2 March/April 1983 163

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PAPER PRESENCE AND SIZE DETECTOR (Cont'd)

Methods of detecting the presence of paper commonly used are optical devices, switches and ultrasonic devices.

Another type of sensor comprises a pinch roller, made either from a metal or conducting rubber, which bears on a metallic or second conducting rubber roller. In the absence of paper, the pinch roller is in contact with the fixed roller, and electrical continuity between the two shafts can be sensed. As shown in Figure 1, when paper is fed between the two rollers, the break in continuity may easily be detected and the presence of the paper sheet recognized.

This concept may be expanded into a paper width detector in two ways. Either a series of narrow rubber rollers, say one inch apart, or a long continuous rubber roller can be in contact with a long metallic roller. In the first case, each roller can be individually monitored and the width and position of the paper deduced to the nearest 1-2 inches. Alternately, the total resistance of all the rubber roller -

met...