Browse Prior Art Database

Document Overlap Detection

IP.com Disclosure Number: IPCOM000076201D
Original Publication Date: 1972-Jan-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Dorr, RL: AUTHOR [+3]

Abstract

A common feeding failure in document transports is the overlap of two or more documents without separation. The present overlap detector uses a single sensor and electronic length measurement to detect double feeds, whereas conventional systems employ two spaced sensors which must be manually adjusted for different document lengths.

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Document Overlap Detection

A common feeding failure in document transports is the overlap of two or more documents without separation. The present overlap detector uses a single sensor and electronic length measurement to detect double feeds, whereas conventional systems employ two spaced sensors which must be manually adjusted for different document lengths.

In Fig. 1, detector 10 is energized by a "start" command 11 on an operator panel when a document run begins. Line 11 sets latch 12 and resets buffer memory 13 to "zero". A sensor pulse on line 14 sets latch 15 upon detection of the leading edge of a document. AND 16 then allows pulses from a stepper- motor emitter 17 to accumulate in counter 18, until latch 15 is reset by a sensor pulse on line 19, indicating the passage of the document's trailing edge. Motor 17 is geared to the document-transport drive. Comparator 20 then emits an "overlap" signal 21 if the contents of counter 18 exceed the number stored in buffer 13, and line 19 resets counter 18 after a delay 22.

The length of the documents in the batch is automatically acquired by gating the contents of counter 18 into buffer 13 through AND 23. Latch 12 is set by a single pulse at the beginning of each batch, and is reset by the trailing edge of each document. Therefore, AND 23 is activated only during the passage of the first document in each batch.

Fig. 2 shows the operation of an improved device that will detect many double feeds which might possibly...