×

Keyboard apparatus

  • US 4,136,336 A
  • Filed: 03/15/1977
  • Issued: 01/23/1979
  • Est. Priority Date: 03/19/1976
  • Status: Expired due to Term
First Claim
Patent Images

1. A keyboard apparatus comprising a pair of tablets each internally carrying two sets of driver lines spaced apart and disposed along coordinate axes and each having its surface subdivided into a multiplicity of key segments associated with each point of intersection between the sets of driver lines;

  • two pairs of scanning units, each pair of scanning units being connected with the two sets of driver lines of one of the tablets, the scanning units being alternately activated to supply a drive signal to the sets of driver lines in a manner such that at least one of each pair of scanning units supplies one set of driver lines of the associated tablet with a drive signal which is time displaced from any drive signal supplied by one of the other pair of scanning units;

    an overlay unit including a plurality of overlays bound in the form of a book so that each overlay can assume an open position on either tablet, each overlay having indicium segments at positions corresponding to the key segments;

    a selection switching device for producing a signal which identifies which one of the overlays assumes an open position on at least one of the tablets;

    a probe for sensing the drive signal from a desired key segment on a selected one of the tablets through the overlays disposed on the tablet; and

    a control unit for supplying a control signal to each of the scanning units and for receiving an output signal from the probe, the control unit producing a digital signal indicative of a desired indicium segment of a particular overlay which assumes an open position on the selected tablet and against which the probe is applied, said particular overlay being specified by an output signal from the selection switching device.

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