(19)
(11) EP 0 318 448 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
26.07.1989 Bulletin 1989/30

(43) Date of publication A2:
31.05.1989 Bulletin 1989/22

(21) Application number: 88850386.9

(22) Date of filing: 09.11.1988
(51) International Patent Classification (IPC)4: B41J 9/42, B41J 7/34
(84) Designated Contracting States:
DE FR GB IT NL

(30) Priority: 23.11.1987 SE 8704630

(71) Applicant: FACIT AKTIEBOLAG
S-172 91 Sundbyberg (SE)

(72) Inventor:
  • Salminen, Olli Olavi
    S-121 48 Johanneshov (SE)

(74) Representative: Onn, Thorsten et al
AB STOCKHOLMS PATENTBYRA, Zacco & Bruhn, Box 23101
104 35 Stockholm
104 35 Stockholm (SE)


(56) References cited: : 
   
       


    (54) A method and arrangement for monitoring the modus operandi of matrix printers


    (57) A matrix printer includes a printing head which incorpo­rates a plurality of printing needles (11), each of which can be maneuvered individually with the aid of a respec­tive electromagnetic maneuvering device (10), by means of which the printing needle (11), carried by a spring-bias­sed, movable armature (12), can be caused to carry out a working cycle, upon activation of the maneuvering device, this working cycle including a working stroke, during which the needle (11) is moved in a direction towards a printing anvil (20) for the purpose of printing a puncti­form sign on a record carrier (21) located in front of the printing anvil, and a subsequent return stroke, during which the printing needle (11) is returned to a withdrawn rest position. For the purpose of enabling simple inexpen­sive, but nevertheless reliable monitoring of the manner of working of the printer, it is proposed that the move­ment of at least one printing needle (11) during at least a part of a needle working cycle is monitored by detecting changes in the magnetic flux in the magnetic circuit (12, 14) of an associated maneuvering device (10) caused by movement of the needle (11).







    Search report