(19)
(11) EP 0 575 204 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
07.12.1994 Bulletin 1994/49

(43) Date of publication A2:
22.12.1993 Bulletin 1993/51

(21) Application number: 93304838.1

(22) Date of filing: 21.06.1993
(51) International Patent Classification (IPC)5: B41J 2/04, B41J 2/045
(84) Designated Contracting States:
DE FR GB IT

(30) Priority: 19.06.1992 US 906091

(71) Applicant: TEKTRONIX, INC.
Wilsonville, Oregon 97070-1000 (US)

(72) Inventors:
  • Stanley, Douglas M., c/o Tektronix, Inc.
    Wilsonville, Oregon 97070-1000 (US)
  • Roy, Joy, c/o Tektronix, Inc.
    Wilsonville, Oregon 97070-1000 (US)
  • Schoening, Susan C., c/o Tektronix, Inc.
    Wilsonville, Oregon 97070-1000 (US)
  • Anderson, Jeffrey J., c/o Tektronix, Inc.
    Wilsonville, Oregon 97070-1000 (US)

(74) Representative: Lawrence, Malcolm Graham 
Hepworth, Lawrence, Bryer & Bizley Merlin House Falconry Court Bakers Lane
Epping Essex CM16 5DQ
Epping Essex CM16 5DQ (GB)


(56) References cited: : 
   
       


    (54) Method of operating an ink jet to achieve high print quality and high print rate


    (57) A drop-on-demand ink jet print head (9) has an ink chamber (22) coupled to a source of ink (11), and an ink drop orifice (103) with an outlet (14,14a,14b). An acoustic driver (36) produces a pressure wave in the ink and causes the ink to pass outwardly through the ink drop orifice and outlet (14,14a,14b). The driver is driven with bipolar drive pulses (100) having a refill pulse component (102) and an eject pulse component (104) of a polarity which is opposite to the refill pulse component (102). The refill and eject pulse components are separated by a wait period (106). The drive pulses may be adjusted to minimize their energy content at a frequency corresponding to the dominant acoustic resonance frequency of the ink jet print head (9). This will accelerate drop breakoff, optimize drop shape and minimize drop speed variations over the range of drop printing rates. The size of the ink drops may be varied, such as by driving the acoustic driver (36) with varying drive signals, preferably utilizing individual or combinations of a plurality of bipolar drive pulses (100). The ink jet printer of the present invention may be used to print with a wide variety of inks, including phase change (hot melt) inks to achieve high print quality at high print rates.






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