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Backspace Mechanism

IP.com Disclosure Number: IPCOM000095956D
Original Publication Date: 1964-Oct-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 74K

Publishing Venue

IBM

Related People

Lennon, KA: AUTHOR [+2]

Abstract

The backspace mechanism has devices for aligning an escapement pawl 10 during certain typewriter operations, such as backspacing, tabulation and carriage return. When the backspace mechanism of the typewriter is actuated, a pull in the direction of arrow 11 is applied to backspace pawl link 12. This rotates backspace bell crank 13 in a counterclockwise direction. Backspace pawl 14 is forced into the teeth of escapement rack 15. Continued pulling on link 12 causes rack 15 and the associated carriage to move to the right in the backspace direction to complete a backspace operation.

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Backspace Mechanism

The backspace mechanism has devices for aligning an escapement pawl 10 during certain typewriter operations, such as backspacing, tabulation and carriage return. When the backspace mechanism of the typewriter is actuated, a pull in the direction of arrow 11 is applied to backspace pawl link 12. This rotates backspace bell crank 13 in a counterclockwise direction. Backspace pawl 14 is forced into the teeth of escapement rack 15. Continued pulling on link 12 causes rack 15 and the associated carriage to move to the right in the backspace direction to complete a backspace operation.

Near the end of a backspacing operation, the backspace mechanism applies a pull to aligning link 18 which pivots aligning lever 19 in a counterclockwise direction into engagement with the forward end of pawl 10. Lever 19 Moves pawl 10 backwardly by a distance equal to the length of pawl slot 20 and holds pawl 10 in this condition. By aligning pawl 10, the backspace movement imparted to rack 15 and associated carriage is limited to a distance only slightly greater than the space occupied by one tooth and one groove on the rack.

If backspacing operations continue until the carriage reaches the left-hand margin position, the margin stop of the typewriter engages tab 20 and pivots margin control bellcrank 22 in a clockwise direction. Bellcrank 22 engages a tab 23 on interlock lever 24 and link 25 is pulled down. This causes shield 26 to move over pawl 14 so that backspaci...