Browse Prior Art Database

Margin Stop Sensing Circuit

IP.com Disclosure Number: IPCOM000085291D
Original Publication Date: 1976-Mar-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 41K

Publishing Venue

IBM

Related People

Kane, MH: AUTHOR [+2]

Abstract

A margin stop sensing circuit is employed to detect the return of a print carrier to its left margin location.

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Margin Stop Sensing Circuit

A margin stop sensing circuit is employed to detect the return of a print carrier to its left margin location.

In printers like the IBM Magnetic Card Executive typewriter, motion of a print carrier along a lead screw effects the generation of emitter pulses. A "home" signal causes the lead screw on which the carrier is mounted to be driven in a reverse direction, causing the carrier to return to its left margin location.

A delay circuit 11 can be employed which is reset by the emitter pulses as long as there is carrier motion. Drive to the lead screw is halted when the delay circuit provides an output signal 15 msec after the last emitter pulse.

The control logic generates a reset pulse with every emitter pulse. The Phi 1, Phi 2, and Phi 3 signals are clock pulses. Delay circuit 11 is reset by the input going high. To make the delay circuit 11 time out, a home signal and a reset are required by AND circuit 2. Reset circuit 3 has the signals EM1, EM2 and Phi 1 for an input. The EM1 signal and the EM2 signal are generated by latches 4 and 5 that follow the emitter signal. The emitter signal is the output of a noise integrator 6. The input to the noise integrator comes from the sensor in the printer.

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