×

Capacitance membrane switchcore with intertrace capacitive coupling and/or intratrace capacitive coupling

  • US 4,857,684 A
  • Filed: 10/25/1988
  • Issued: 08/15/1989
  • Est. Priority Date: 10/25/1988
  • Status: Expired due to Fees
First Claim
Patent Images

1. A capacitance membrane switchcore for a keyboard having a plurality of operator actuatable key sites and including drive circuitry and sense circuitry to be connected to the switchcore, the capacitance membrane switchcore comprising (i) a dielectric layer, (ii) a conductive first circuit along a first surface of the dielectric layer that includes a plurality of conductive first traces and a plurality of first capacitor plates, (iii) a conductive second circuit along a second surface of the dielectric layer opposite from the first surface thereof that includes a plurality of conductive second traces and a plurality of second capacitor plates, and (iv) the first traces and the second traces are arranged relative to each other so as to define a matrix comprising a plurality of key cells, each including a fixed capacitor consisting of a first capacitor plate and a second capacitor plate that is unique to each key cell,the improvement wherein the capacitance membrane switchcore further includes:

  • a conductive third circuit along the same surface of the dielectric layer as the first circuit and including a plurality of conductive third traces, there being one third trace for each second trace of the second circuit;

    an intertrace coupling capacitor coupling each second trace of the second circuit to a selected third trace of the third circuit, there being one intertrace coupling capacitor for each second trace, each intertrace coupling capacitor including a capacitor plate along the same surface of said dielectric layer as the second circuit and a capacitor plate along the same surface of said dielectric layer as the third circuit; and

    the first traces and third traces are arranged for connection to drive circuitry and sense circuitry of a keyboard.

View all claims
  • 5 Assignments
Timeline View
Assignment View
    ×
    ×