(19)
(11) EP 0 406 957 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
03.04.1991 Bulletin 1991/14

(43) Date of publication A2:
09.01.1991 Bulletin 1991/02

(21) Application number: 90201737.5

(22) Date of filing: 29.06.1990
(51) International Patent Classification (IPC)5: H01F 7/16, B41J 2/285
(84) Designated Contracting States:
DE FR GB IT SE

(30) Priority: 05.07.1989 US 376068

(71) Applicant: North American Philips Corporation
New York, N.Y. 10017 (US)

(72) Inventors:
  • Wang, Ping-Shih
    NL-5656 AA Eindhoven (NL)
  • Ang, Chwee Peng
    NL-5656 AA Eindhoven (NL)

(74) Representative: Cuppens, Hubertus Martinus Maria et al
INTERNATIONAAL OCTROOIBUREAU B.V., Prof. Holstlaan 6
5656 AA Eindhoven
5656 AA Eindhoven (NL)


(56) References cited: : 
   
       


    (54) Hammer solenoid


    (57) A hammer solenoid for impact printers includes a hollow ferromagnetic plunger. A ferromagnetic flux booster is attached to the rear end of the plunger to enhance the characteristics of the solenoid by shifting the magnetic center of the plunger while, at the same time, providing a dead structure which minimizes vibration and bounce. In an alternate embodiment, the plunger walls may include a permanent magnet which is polarized to be attracted by the solenoid coil.







    Search report