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Touch panel controller, touch panel device, and electronic information device

  • US 9,606,684 B2
  • Filed: 06/18/2013
  • Issued: 03/28/2017
  • Est. Priority Date: 06/27/2012
  • Status: Active Grant
First Claim
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1. A touch panel controller comprising:

  • a plurality of driving circuits that drive respective drive lines of a capacitive touch panel by supplying driving signals to the respective drive lines,length of rise time and fall time of each of the driving signals being variable;

    said controller further comprising;

    a control section that controls the lengths of rise time and fall time,each of the plurality of driving circuits including a plurality of inverter circuits which are configured to change the length of rise time and fall time,the plurality of inverter circuits include (i) one (1) first inverter circuit, (ii) a plurality of second inverter circuits, and (iii) a plurality of switches whose number is identical with that of the plurality of second inverter circuits;

    an input terminal of the first inverter circuit serving as an input terminal of the driving circuit,the plurality of second inverter circuits being configured by respective transistors having different channel widths,the plurality of second inverter circuits being connected in series with the respective plurality of switches so as to constitute a plurality of series circuits whose number is identical with that of the plurality of second inverter circuits and that of the plurality of switches,the plurality of series circuits being connected in parallel with each other between an output terminal of the first inverter circuit and an output of the driving circuit, andthe control section selectively operating the plurality of inverter circuits by controlling ON/OFF of each of the plurality of switches until (i) extraneous emission of an electromagnetic wave (EMI) from the touch panel satisfies a predetermined criterion, and (ii) touch location detection sensitivity of the touch panel satisfies a predetermined criterion, the control section changing a synthesis channel width of the plurality of second inverter circuits so as to change the lengths of rise time and fall time of each of the driving signals.

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