Browse Prior Art Database

Dynamic Sheet Length Sensing

IP.com Disclosure Number: IPCOM000083663D
Original Publication Date: 1975-Jul-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Church, WE: AUTHOR [+2]

Abstract

This sensing system dynamically measures the length of a paper sheet as it is fed from a sheet supply tray to a paper processing path. Tray 10 supports a stack of sheets 11 with their rear edges registered against stop 12. These sheets may be of a short length 13 or a longer length 14.

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Dynamic Sheet Length Sensing

This sensing system dynamically measures the length of a paper sheet as it is fed from a sheet supply tray to a paper processing path. Tray 10 supports a stack of sheets 11 with their rear edges registered against stop 12. These sheets may be of a short length 13 or a longer length 14.

Picker drive roller 15 is selectively controlled to feed only the top sheet to the nip formed by separator roller 16 and restraint roller 17. When the leading edge of this sheet interrupts the light path between lamp 18 and photocell 19, counter logic network 20 is enabled to begin counting the output pulses of rotary pulse generator 21.

This pulse generator provides an output pulse for each unit of rotational movement thereof, for example, 500 pulses per revolution. Thus, the number of output pulses can be counted as a measure of the length of the sheet. This pulse generator stops rotating when the sheet's rear edge moves thereunder, on its way to roller 15.

For example, the rear edge of a short sheet 13 will have moved the distance 22 from stop 12 when the sheet's leading-edge causes logic 20 to begin counting the output pulses from pulse generator 21.

However, the rear edge of a long sheet 14 will have moved a shorter distance 23 from stop 12 when that sheet's leading edge causes logic 20 to begin counting. Thus, the residual count in logic 20, when pulse generator 21 stops rotating, or when photocell 19 detects the sheet's rear edge, will be less fo...