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Extended Printer Hammer Error Detection

IP.com Disclosure Number: IPCOM000062063D
Original Publication Date: 1986-Oct-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 55K

Publishing Venue

IBM

Related People

Carrington, JE: AUTHOR

Abstract

Print hammer driver circuits can be checked each option time by extending the hammer check window with a delay bit that is controlled by a delay count buffer containing the flight time delay value for each print position. Referring to Figs. 1 and 2, the control sequence for checking hammer driver circuits having variable turn-on and turn-off times is as follows: 1. Prior to a print line buffer and print band data comparison and during the time that each print position is addressed or optioned, the on-off status of the hammer driver is checked for an off condition by gating a hammer echo (HMR ECHO) signal through AND gate 10, under control of an ENABLE bit, to hammer misfire latch 11. The ENABLE bit is generated from check buffer 12 for the specific print position addressed.

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Extended Printer Hammer Error Detection

Print hammer driver circuits can be checked each option time by extending the hammer check window with a delay bit that is controlled by a delay count buffer containing the flight time delay value for each print position. Referring to Figs. 1 and 2, the control sequence for checking hammer driver circuits having variable turn-on and turn-off times is as follows: 1. Prior to a print line buffer and print band data comparison and during the time that each print position is addressed or optioned, the on-off status of the hammer driver is checked for an off condition by gating a hammer echo (HMR ECHO) signal through AND gate 10, under control of an ENABLE bit, to hammer misfire latch 11. The ENABLE bit is generated from check buffer 12 for the specific print position addressed. If the HMR ECHO signal indicates the hammer is on, then a HMR Misfire error signal is generated by latch 11. If a HMR ECHO signal did not indicate the hammer driver was on, then latch 11 remains reset and no HMR Misfire signal is generated. This process is repeated each scan time that the print position is addressed until a comparison of the print and band data occurs. 2. When print buffer and band data match, a compare signal 13 (Fig. 2) is generated that turns off the ENABLE bit and turns on a DELAY bit in check buffer 12. Misfire checking continues to be done while the DELAY bit is on. Each subsequent option of the hammer position increments a "Check...