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Touch panel sensing circuit

  • US 20110102061A1
  • Filed: 10/20/2010
  • Published: 05/05/2011
  • Est. Priority Date: 10/30/2009
  • Status: Active Grant
First Claim
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1. A touch panel sensing circuit for sensing a voltage variation of a coupling capacitor formed between a first directional signal line and a second directional signal line separated from the first directional signal line when an object approaches, the touch panel sensing circuit comprising:

  • an input voltage source for producing a plurality of periodic voltage cycles;

    a first voltage switch having a first terminal connected to the input voltage source and a second terminal connected to the first directional signal line;

    a common voltage source for providing a DC common voltage;

    a second voltage switch having a first terminal connected to the common voltage source and a second terminal connected to the first directional signal line;

    a first switch having a first terminal connected to the second directional signal line;

    an amplifier having an inverting input terminal connected to a second terminal of the first switch;

    a second switch having a first terminal connected to the inverting input terminal of the amplifier;

    a third switch having a first terminal connected to a second terminal of the second switch and a second terminal connected to the common voltage source;

    a fourth switch having a first terminal connected to the inverting input terminal of the amplifier;

    a first feedback capacitor having a first terminal connected to a second terminal of the fourth switch;

    a fifth switch having a first terminal connected to a second terminal of the first feedback capacitor and a second terminal connected to an output terminal of the amplifier;

    a sixth switch having a first terminal connected to the input voltage source and a second terminal connected to the second terminal of the first feedback capacitor;

    a seventh switch having a first terminal connected to the second terminal of the fourth switch and a second terminal connected to the common voltage source;

    an eighth switch having a first terminal connected to the inverting input terminal of the amplifier and a second terminal connected to the output terminal of the amplifier; and

    a third voltage switch having a first terminal connected to a non-inverting input terminal of the amplifier, a second terminal connected to the common voltage source and a third terminal connected to the input voltage source.

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