(19)
(11) EP 0 622 209 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
22.02.1995 Bulletin 1995/08

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

(21) Application number: 94106002.2

(22) Date of filing: 18.04.1994
(51) International Patent Classification (IPC)5: B41J 2/175, B41J 2/19
(84) Designated Contracting States:
DE FR GB IT

(30) Priority: 30.04.1993 US 56698

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

(72) Inventors:
  • Canfield, Brian
    San Diego, CA 92109 (US)
  • Mebane, Janet E.
    San Diego, CA 92131 (US)
  • Walsh, William J.
    Poway, CA 92064 (US)
  • Xu, Yinan
    Poway, CA 92064 (US)

(74) Representative: Liesegang, Roland, Dr.-Ing. et al
FORRESTER & BOEHMERT Franz-Joseph-Strasse 38
80801 München
80801 München (DE)


(56) References cited: : 
   
       


    (54) Method for detecting and correcting an intrusion of air into a printhead substrate of an ink jet cartridge


    (57) An intrusion of air (22) into the ink chambers (24) of a printhead substrate (50) is a symptom of either a depleted ink supply (26) or a deprimed printhead substrate (50). When the printer (20) attempts to print with a depleted ink supply (30) or a deprimed printhead substrate (50), the printhead substrate (50) must absorb all of the energy dissipated in the ink chambers (24) to eject the drops. This causes the printhead substrate (50) to reach high temperatures. The present invention detects a depleted ink supply (26) and a deprimed printhead (50) by monitoring the temperature of the printhead substrate (50) and comparing this temperature with a threshold (84, 90, 96). When this temperature exceeds the threshold (84, 90, 96) for more than an allotted amount of time, then corrective action is taken.






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