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Thermal ink jet print device having phase change cooling

  • US 5,272,491 A
  • Filed: 04/03/1992
  • Issued: 12/21/1993
  • Est. Priority Date: 10/31/1990
  • Status: Expired due to Term
First Claim
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1. A thermal ink jet print device, comprising:

  • a body having a first cavity containing ink and having a second cavity containing a phase change material;

    a rectangular printhead having a plurality of nozzles through which ink is ejected, said printhead having a rectangular back face disposed on said body adjacent said first cavity and said second cavity, said rectangular back face having a length dimension larger than a width dimension, said rectangular printhead having a length-wise slot formed through said back face and substantially centered with respect to said width dimension of said back face so as to divide said back face into a first half and a second half, said slot being in fluid communication with said first cavity via an ink passage for allowing ink to flow into priming cavities, each priming cavity being associated with one of said nozzles;

    electrical heating means at each priming cavity for each nozzle of the plurality of nozzles, each electrical heating means when heated ejecting ink from the priming cavity through the nozzle thereat;

    said second cavity comprising a first half portion and a second half portion, said first half portion having a first wall only contacting said first half of said back face of said printhead, said second half portion having a second wall only contacting said second half of said back face of said printhead,said ink passage, in fluid communication with said slot, running between said first half portion and said second half portion of said second cavity,said phase change material in said second cavity having two physical states with change from one physical state to the other physical state in the presence of printhead heat energy at a predetermined printhead temperature below that at which unacceptable printing occurs,said phase change material in said second cavity being in heat exchange relationship with said back face of said printhead to be exposed to and to absorb printhead heat energy in changing physical state, said phase change material existing in both physical, states during phase change cooling and having a rate of change of physical state at said predetermined temperature which is substantially commensurate with the rate of delivery of heat energy by said printhead.

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