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Protective Circuit

IP.com Disclosure Number: IPCOM000094088D
Original Publication Date: 1966-May-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 70K

Publishing Venue

IBM

Related People

Martin, VC: AUTHOR

Abstract

A protective circuit for a chain printer utilizes Coil Protect latch 10. The latter operates after a 2 millisecond delay from delay 12 to remove the 60 volt supply voltage should there be a potential hazard to any hammer coil. This is done by first operating Head Check Reset latch 14 in response to a Check Reed Closed signal through And 15 from reed switch 16. This has a operating coil connected in the

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Protective Circuit

A protective circuit for a chain printer utilizes Coil Protect latch 10. The latter operates after a 2 millisecond delay from delay 12 to remove the 60 volt supply voltage should there be a potential hazard to any hammer coil. This is done by first operating Head Check Reset latch 14 in response to a Check Reed Closed signal through And 15 from reed switch 16. This has a operating coil connected in the

The condition of the reed switch contacts is checked by transistor TR1 in response to a Check Reed Sample signal from Or 18. The latter which mixes Not Print Delayed, Not Reed Check single-shot 19 and Not Compare from And 20 through holdover delay 21, and a delayed Print signal from delay 22 ad single- shot 24. This occurs when the reed switch is checked by a check pulse from driver 26 in response to a Print signal.

The Head Check Reset latch 14 is set by the Check Reed Closed signal from And 15; a Not Check Reed Closed signal from And 32 during a reed switch check; Hammer Driver on too long, too often, or without a compare, from Or 34; and through And 35 and Or 36 for Scan Trigger on for longer than 1 millisecond from delay 37, No Print Scan for 1 millisecond from holdover delay 38, ad Not Home Drum Pulse ad Not Check Drum pulse through holdover delay 40 and 42, on the higher speed printers.

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