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Simple, sensitive, frequency-tuned drop detector

  • US 4,835,435 A
  • Filed: 01/19/1988
  • Issued: 05/30/1989
  • Est. Priority Date: 01/19/1988
  • Status: Expired due to Term
First Claim
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1. A detector for detecting a drop of ink of the type typically present in an ink jet printer, the detector comprising:

  • a. a cover plate, defining through itself a first slot having a first long dimension;

    b. a substrate, defining through itself a second slot having a second long dimension disposed to be aligned generally parallel with the first long dimension;

    c. a membrane;

    i. fabricated from a piezoelectric material which generates an electric signal in response to being impacted by a drop;

    ii. frequency tunable to a range of selected resonant frequencies;

    iii. secured at least at two locations between the cover plate and the substrate;

    iv. formed with a floating region;

    (1) having a generally rectangular area defined by;

    (a) a pair of short ends, opposite one another, defining the shorter width dimensions of the floating region, and(b) a pair of membrane lengths, opposite one another, defining the longer length dimensions of the floating region;

    (2) suspended across and between the slots with the pair of short ends being unsecured and therefore free to move;

    (3) aligned with the membrane lengths generally parallel with the long dimensions of the slots;

    (4) positioned to be impacted by and thereby detect the drop; and

    d. a conductor means, electrically coupled to the membrane, for transmitting to an external environment the electric signal generated by the membrane.

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