(19)
(11) EP 0 490 643 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
21.10.1992 Bulletin 1992/43

(43) Date of publication A2:
17.06.1992 Bulletin 1992/25

(21) Application number: 91311480.7

(22) Date of filing: 10.12.1991
(51) International Patent Classification (IPC)5: B41J 9/44, B41J 9/28
(84) Designated Contracting States:
DE FR GB

(30) Priority: 11.12.1990 US 625569

(71) Applicant: XEROX CORPORATION
Rochester New York 14644 (US)

(72) Inventors:
  • Gottwald, Johannes F.
    Park Ridge, IL, 60068 (US)
  • Gruber, Dennis W.
    Arlington Heights, Il, 60005 (US)

(74) Representative: Goode, Ian Roy et al
Rank Xerox Ltd Patent Department Parkway
Marlow Buckinghamshire SL7 1YL
Marlow Buckinghamshire SL7 1YL (GB)


(56) References cited: : 
   
       


    (54) Impact printers


    (57) An impact printer (10) includinges a platen (18), a carriage (32) mounted for reciprocating movement generally parallel to the platen, a rotatable print element (50) having character imprinting portions disposed thereon, the characters being assigned a class designation according to their imprinting area, a print element selector for moving the print element to position a selected character portion at a printing position, a hammer (82) for driving the character portions to deform the platen, and means for driving the hammer toward and away from the platen. Different impact speeds are assigned to the hammer in accordance with the character portion class designations. The rate of hammer displacement is varied as it is moved from a home position to an impact position so that the hammer initially moves through a first region at an increasing speed and subsequently moves through a second region at a substantially-constant speed. A counter is incremented periodically in response to the hammer movement for determining the instantaneous location and speed of the hammer, and the counter is reset with a predetermined count, notwithstanding the actual count, at a location within the second region.






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