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Browse Prior Art Database

LEAD EDGE SENSOR

IP.com Disclosure Number: IPCOM000024678D
Original Publication Date: 1981-Aug-31
Included in the Prior Art Database: 2004-Apr-02
Document File: 2 page(s) / 72K

Publishing Venue

Xerox Disclosure Journal

Abstract

An edge or position sensor design capable of detecting the leading edge of a moving document to within + 5 millimeters. In the accompanying figure the sensor 1 comprises a photo tTansistor 2 fixed with respect to a plastic housing having a number of segments labeled A-D. An optically transparent belt 3 periodically moves documents 4 past the sensor 1 which is used to detect the passage of each document past a 5 mil width optical window 6. A light source 7 is positioned on a side of the belt 3 removed from the sensor 1 so the documents disrupt the light passing to the sensor and accordingly reduce conduction in the photo transistor

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Page 1 of 2

XEROX DISCLOSURE JOURNAL

LEAD EDGE SENSOR David D. Johnson Ernest B. Page

Proposed Classification
U.S. CI. 355/35H
Int. C1. G03b

MAXIMUM OPTICAL

WINDOW

I

I I

/ /

3 4

1

7

\

Volume 6 Number 4 July/August 1981 199

[This page contains 1 picture or other non-text object]

Page 2 of 2

LEAD EDGE SENSOR (Cont'd)

An edge or position sensor design capable of detecting the leading edge of a moving document to within + 5 millimeters. In the accompanying figure the sensor 1 comprises a photo tTansistor 2 fixed with respect to a plastic housing having a number of segments labeled A-D. An optically transparent belt 3 periodically moves documents 4 past the sensor 1 which is used to detect the passage of each document past a 5 mil width optical window 6. A light source 7 is positioned on a side of the belt 3 removed from the sensor 1 so the documents disrupt the light passing to the sensor and accordingly reduce conduction in the photo transistor


2.

The sensor is the equivalent of a 5 mil slot even though each opposing surface is a least 60 mils apart. The gaps between surfaces allow an air flow 8 injected into the housing to flow out the housing bottom keeping the sensor 1 free from dirt.

The sensor's performance is better than a conventional 5 mil slot. This is proabably due to the "slottt walls not being present. With a standard slot, light not only travels up the slot in a straight line, but also reflects off the walls. In the present design, much of the wall is missing and t...