Title: Non return to home rack shift selection mechanism for a single element printer

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Claims: We claim:

1. A printer having a type element mounted for rotation to present different characters to a print position, a pinion connected to said type element for rotation therewith, a drive device comprising a pair of rack members alternately positionable to engage diametrically opposite portions of said pinion, and means for driving an engaged rack member a measured distance wherein the improvement comprises:

a rack selection mechanism for shifting said rack members into and out of engagement, said rack selection mechanism comprising a pivot member spacially fixed with respect to said printhead;

a first cam follower means pivotally mounted on said pivot member;

a second cam follower pivotally supported on said pivot member;

a third cam follower pivotally supported on said pivot member;

said first cam follower means supporting for monoaxial displacement relative thereto, a selectably displaceable member for coupling said first cam follower means alternatively with said second and said third cam followers;

said first cam follower means positively engaging said drive device to impart bidirectional movement to said drive device;

a first cam, rotationally engageable with said first cam follower;

second cam rotationally engageable with said second cam follower, said first and second cam followers spacially displaced such that said first and second followers can not be simultaneously engaged by the respective first and second cams;

third cam engageable with said third cam follower to shift said first cam follower about said pivot member when said displaceable member is engaged with said third follower, said cams being axially movable into and out of engagement with said respective followers.

Other info:

Inventors: Abell, Jr., William A. (Lexington, KY, US)
Field, Thomas R. (Lexington, KY, US)
Haus, Ralph A. (Lexington, KY, US)
Shakib, Iraj D. (Lexington, KY, US)

Application Number: 535391
Filing Date: 1974-12-23
Publication_date: 1976-09-21
Assignee: International Business Machines Corporation (Armonk, NY)
Primary Class(es): 400/161.5 400/161.4, 400/320
Other Classes:
US Patent Ref:

3352398	Nov, 1967	Crutcher et al.	197/16.
3559791	Feb, 1971	Waldenburger	197/55.
3572486	Mar, 1971	Hebel et al.	197/55.
3596745	Aug, 1971	Waldenburger	197/55.
3666070	May, 1972	Schaefer	197/18.
3738471	Jun, 1973	Werff et al.	197/16.
3876053	Apr, 1975	Giolitti et al.	197/18.

Other Refs:
Primary Examiner: Burr, Edgar S.
Assistant Examiner: Rader, R. T.
Attorney: Letson; Laurence R.