(19)
(11) EP 0 622 198 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
08.02.1995 Bulletin 1995/06

(43) Date of publication A2:
02.11.1994 Bulletin 1994/44

(21) Application number: 94302813.4

(22) Date of filing: 20.04.1994
(51) International Patent Classification (IPC)5: B41J 2/16
(84) Designated Contracting States:
DE FR GB IT

(30) Priority: 29.04.1993 US 55466

(71) Applicant: Hewlett-Packard Company
Palo Alto, California 94304 (US)

(72) Inventors:
  • Holstun, Clayton L.
    Escondido, California 92026 (US)
  • Courian, Kenneth J.
    San Diego, California 92130 (US)

(74) Representative: Colgan, Stephen James et al
CARPMAELS & RANSFORD 43 Bloomsbury Square
London WC1A 2RA
London WC1A 2RA (GB)


(56) References cited: : 
   
       


    (54) Thermal ink-jet pen


    (57) Spray (or satellite drops) in thermal ink-jet pens firing inks containing polymer dispersants for pigments is reduced by increasing the distance between the firing resistor (10) and the nozzle (12). This may be done by offsetting the resistor with respect to the nozzle, increasing the thickness of the orifice plate (14), increasing the thickness of the barrier layer (18) which defines the firing chamber (20) and supports the nozzle plate, or recessing the resistor deeper into the substrate (16) on which it is supported. Any or all of the foregoing may be implemented to reduce spray. A combination of thicker top plates and offsetting the nozzle relative to the resistor is particularly efficacious in reducing spray.






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