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Browse Prior Art Database

Check Circuit

IP.com Disclosure Number: IPCOM000084388D
Original Publication Date: 1975-Nov-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Ernst, LM: AUTHOR [+2]

Abstract

This circuit checks the operability of a detecting circuit. The detecting circuit is designed to detect failure to detack a sheet of paper from the photoconductor at the transfer station of a xerographic copier.

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Check Circuit

This circuit checks the operability of a detecting circuit. The detecting circuit is designed to detect failure to detack a sheet of paper from the photoconductor at the transfer station of a xerographic copier.

Photoconductor drum 10 carries a toned latent image to transfer station 11 whereat the toner is transferred to sheet paper 12, as by the use of transfer corona 13. The photoconductor drum includes interior supply and take-up reels whereby the photoconductor is renewable. The photoconductor enters and exits the drum at drum seal 14. Photocell/light-source couple 15 is provided to direct a pulsating, on/off beam of light toward the photoconductor downstream of the transfer station. The light source within couple 15 is strobed on and off at a 60 cps rate by clock input line 16.

So long as paper properly detacks (i.e.,; leaves the photoconductor at transfer station 11), the photocell 15 views only light reflected from the photoconductor, or the drum seal 14. However, if paper fails to leave the photoconductor at the transfer station 11, light will be reflected off the paper 12.

The 60 cps photocell output signal, on conductor 17, is at least 0.3 volt magnitude when light is reflected off the photoconductor; is at least 2 volts magnitude when light is reflected off paper 12; and is substantially zero when light is reflected off the drum seal 14.

Threshold detecting circuit 18 sets its output latch and provides an output to stop the copier when a...