Browse Prior Art Database

Sensing Sheet Movement

IP.com Disclosure Number: IPCOM000051897D
Original Publication Date: 1981-Mar-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Yanker, GM: AUTHOR

Abstract

In reverse shingling techniques for separating sheets prior to feeding in the opposite direction, it is customary to detect the position of the trailing edge in order to know when to change the drive direction. This presents some difficulty when it is desired to feed interspersed sheets having different lengths. That is, the means for detecting the trailing edge must be readjusted, and sheets of the same length must be fed at the same time. Illustrated and described here is a means for detecting movement of the leading edge of the sheet which overcomes the disadvantages mentioned above.

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Sensing Sheet Movement

In reverse shingling techniques for separating sheets prior to feeding in the opposite direction, it is customary to detect the position of the trailing edge in order to know when to change the drive direction. This presents some difficulty when it is desired to feed interspersed sheets having different lengths. That is, the means for detecting the trailing edge must be readjusted, and sheets of the same length must be fed at the same time. Illustrated and described here is a means for detecting movement of the leading edge of the sheet which overcomes the disadvantages mentioned above.

Fig. 1 shows a stack of sheets 1 held substantially vertically (but is workable in any orientation) for feeding automatically to a typewriter or other printer (by means not shown). Stack 1 is biased against re straining knife 2 by, e.g., a spring (not shown). Knife 2 keeps the sheets in position until they are moved in the direction of arrow 3 by a picker/separator (not shown), which may be of the roll wave generator type. Leading edge position sensing occurs at position 4 near knife 2.

Fig. 2 is an enlarged illustration of several sheets 10 which comprise stack 1. Restraining knife 2 is not shown in Fig. 2, but a sheet position detecting means is positioned corresponding to location 4 shown in Fig. 1.

This sensing technique operates on the principle that when a fiber-optic detector, such as 14, is immediately adjacent a sheet 10A, no light from source 16 tr...