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Character Selection System

IP.com Disclosure Number: IPCOM000077598D
Original Publication Date: 1972-Aug-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 3 page(s) / 58K

Publishing Venue

IBM

Related People

Steinfort, WO: AUTHOR

Abstract

Type element 10 is rotated to selectively position different characters to a printing point by rotation of shaft 11, as controlled by a pair of ratchets 12 and 13 in response to counting logic circuitry 14, which receives position input in the form of pulses from an emitter wheel 15. Shaft 11 receives motion through a slipping friction clutch 16 and is normally held in a stationary position by engagement of a pawl 17 with the ratchet 13. A magnet latch 18 normally traps the pawl 17 in its holding position against force of spring 19. Logic circuitry 14 has memory capacity for comparing the current position of type element 10 with a new desired position, as indicated from input conduit 20, and determining a difference in terms of the number of angular increments type element 10 must be moved to reach the new position.

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Character Selection System

Type element 10 is rotated to selectively position different characters to a printing point by rotation of shaft 11, as controlled by a pair of ratchets 12 and 13 in response to counting logic circuitry 14, which receives position input in the form of pulses from an emitter wheel 15. Shaft 11 receives motion through a slipping friction clutch 16 and is normally held in a stationary position by engagement of a pawl 17 with the ratchet 13. A magnet latch 18 normally traps the pawl 17 in its holding position against force of spring 19. Logic circuitry 14 has memory capacity for comparing the current position of type element 10 with a new desired position, as indicated from input conduit 20, and determining a difference in terms of the number of angular increments type element 10 must be moved to reach the new position. Logic circuitry 14 controls electromagnet 21 to drop armature 22 when the desired position has been reached. Circuitry 14 further energizes electromagnet 23 to release pawl 17 and ratchet 13 for selection motion, and de-energizes electromagnet 23 at the proper time within a printing cycle to initiate rotation of print shaft 27.

In operation, input from conduit 20 causes computation by circuitry 14 to determine a number of spaces for shaft 11 to be positioned. Electromagnet 23 is pulsed to release pawl 17 for withdrawal by its spring 19 from ratchet 13. This release motion also causes hook 24 to engage print shaft start clutch latch 25.

The time to print a character is determined by the variable time necessary to position the type element 10 and the fixed time necessary to drive the type element 10 through an impact stroke. Ideally these times are somewhat overlapped. Electromagnet 23 is controlled by logic 14 to initiate the print stroke at the earliest possible time in the selection of a character to maximize this overlap, while still insuring complete selection prior to impact. Initiation of an impact stroke occurs upon deactivation of magnet 23, which allows spring 26 to pull prin...