Browse Prior Art Database

Document Detector System

IP.com Disclosure Number: IPCOM000096476D
Original Publication Date: 1963-Jun-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Cutaia, A: AUTHOR [+3]

Abstract

Some document handing systems develop a timing gate from the leading edge of the document. The signal developed by the leading edge is. used to produce a second signal equal to the length of the document. These systems are used where the documents are of the same length. Holes and tears in the document, however, can give a false indication of seeing the trailing edge.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 56% of the total text.

Page 1 of 2

Document Detector System

Some document handing systems develop a timing gate from the leading edge of the document. The signal developed by the leading edge is. used to produce a second signal equal to the length of the document. These systems are used where the documents are of the same length. Holes and tears in the document, however, can give a false indication of seeing the trailing edge.

To deal with holes and tears in the document and also provide for variable length documents, light waves from light source 10 are reflected from document 15 so as to impinge upon document detector 20. The output detector 20 is connected to the base of transistor T3, a constant current source for charging capacitor C. Capacitor C is connected in the coupling circuit between the collector of transistor T1 and the base of transistor T2. Output terminal 25 is connected to the collector of T2. This also connects to the base of T1, forming a feedback loop.

The output from detector 20 rises upon detecting the leading edge of document 15. It then falls upon detecting a mark or hole or tear in mark, hole or tear. It rises again until the trailing edge of the document passes the document detector. However, the wave form at terminal 25 rises as detector 20 sees the leading edge of the document. It remains up for the entire length of the document, plus a fixed delay, even though the signal from detector 20 goes down as it sees holes.

When there is no document under detector 20, T1 is cu...