Browse Prior Art Database

Selection Detent Inhibit

IP.com Disclosure Number: IPCOM000085517D
Original Publication Date: 1976-Apr-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Hoskins, JA: AUTHOR [+3]

Abstract

This barrel cam selection mechanism is designed so that it is necessary to shift the rotate rack at print point to do a shift operation. On a 96-character type head a six-unit selection (90 degrees rotation of type head) is a normal detent position, and it is therefore desirable to allow the head to detent while the rack is shifted. On an 88-character type head arrangement, the six-unit selection becomes a 5-1/2 unit selection, resulting in the detent lining up with the tip of a tooth rather than the bottom of a notch.

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Selection Detent Inhibit

This barrel cam selection mechanism is designed so that it is necessary to shift the rotate rack at print point to do a shift operation. On a 96-character type head a six-unit selection (90 degrees rotation of type head) is a normal detent position, and it is therefore desirable to allow the head to detent while the rack is shifted. On an 88-character type head arrangement, the six-unit selection becomes a 5-1/2 unit selection, resulting in the detent lining up with the tip of a tooth rather than the bottom of a notch.

In order to maintain reliable rack shifting at print point with this condition, it is necessary to keep the detent from entering the type head causing rack and pinion misalignment and excessive type head tooth wear. This is accomplished by utilizing the fact that a shift operation is a no-print function.

In such a machine a no-print operation results when the velocity slider is held at home. Therefore, the lack of slider motion is used to cripple an intermediate cam follower linkage 10 which will not allow the rotate and tilt detent arm 12 to follow the cam 14, because latch 16 remains engaged with the detent arm 12. During normal printing, cam follower 10 follows cam 17 and engages latch 16 to disengage it from the detent arm 12 allowing normal detenting.

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