(19)
(11) EP 0 237 787 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
13.01.1988 Bulletin 1988/02

(43) Date of publication A2:
23.09.1987 Bulletin 1987/39

(21) Application number: 87101964

(22) Date of filing: 12.02.1987
(84) Designated Contracting States:
DE FR GB IT

(30) Priority: 20.03.1986 US 842593

(71) Applicant: Hewlett-Packard Company
 ()

(72) Inventor:
  • Nielsen, Niels
     ()

   


(54) Method and apparatus for maintaining a substantially constant ink pressure at a remotely fed ink printhead


(57) Pressure surging and variations in ink supply in a remote source reservoir ink jet printing system are eliminated in a unique method and implementing apparatus employing a simple elastically suspended reservoir. The weight of the reservoir is kept negligibly small in relation to the weight of the ink. The elastic constant is selected so that the reservoir rises as the ink supply diminishes maintaining the surface of the ink at a relatively constant height with respect to the printhead, independantly of the depth of the ink in the reservoir. This maintains the hydrostatic pressure head (slightly negative in this application) relatively constant in relation to the print­head which is supplied by the reservoir. Any elastic system operating in tension, compression, bending, torsion and so on is contemplated.







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