Intoduction to mTouch Capacitive Touch Sensing

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Introduction of mTouch Capacitive touch sensing technology and the construction of the sensors

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Intoduction to mTouch Capacitive Touch Sensing

  1. 1. Introduction to mTouch™ Capacitive Touch Sensing <ul><li>Source: Microchip </li></ul>
  2. 2. Introduction <ul><li>Purpose </li></ul><ul><li>This module will discuss a number of topic including what exactly is mTouch Capacitive Touch Sensing and describe sensor construction. </li></ul><ul><li>Outline </li></ul><ul><li>What is mTouch Capacitive Touch Sensing </li></ul><ul><li>Main components: </li></ul><ul><ul><li>Touch Sensor </li></ul></ul><ul><ul><li>Relaxation Oscillator Circuit </li></ul></ul><ul><ul><li>Frequency Measurement </li></ul></ul><ul><li>Content </li></ul><ul><li>27 pages </li></ul><ul><li>Duration </li></ul><ul><li>15 minutes </li></ul>
  3. 3. What is mTouch™ Capacitive Touch Sensing? <ul><li>Alternative to traditional push-butt on user interfaces </li></ul><ul><li>No mechanical movement </li></ul><ul><li>Completely sealed </li></ul><ul><li>Modern-looking design </li></ul><ul><li>Royalty-Free license! </li></ul><ul><li>Microchip provides a multitude of resources to ease the design process </li></ul>
  4. 4. Overview of mTouch™ Capacitive Touch Sensing
  5. 5. Relaxation Oscillator Circuit
  6. 6. Frequency Measurement
  7. 7. Equation of Capacitance
  8. 8. Touch Sensor Construction <ul><li>Fiberglass (FR-4) Printed Circuit Board (PCB) </li></ul><ul><ul><li>Laminate made from woven glass fiber impregnated with epoxy resin </li></ul></ul>
  9. 9. Touch Sensor Construction cont’d <ul><li>Copper (Cu) pads (thickness exaggerated) </li></ul>
  10. 10. Touch Sensor Construction cont’d <ul><li>Glass or Plexiglas® </li></ul><ul><ul><li>2 to 5mm thick </li></ul></ul>
  11. 11. How does it work? <ul><li>Introduction of finger produces a parallel capacitance </li></ul>
  12. 12. Equivalent Circuit
  13. 13. RC Circuit Without finger introduced With finger introduced Figure 1 Figure 2
  14. 14. Oscillator Circuit
  15. 15. Oscillator Circuit cont’d
  16. 16. Oscillator Circuit cont’d
  17. 17. Oscillator Circuit cont’d
  18. 18. Oscillator Operation
  19. 19. Oscillator Operation cont’d
  20. 20. Oscillator Operation cont’d
  21. 21. Oscillator Operation cont’d
  22. 22. Oscillator Operation cont’d
  23. 23. Oscillator Operation cont’d
  24. 24. Frequency Measurement
  25. 25. Frequency Measurement cont’d
  26. 26. Frequency Measurement cont’d
  27. 27. Frequency Measurement cont’d
  28. 28. Additional Resource <ul><li>For ordering the Microchip PICmicro® MCUs, please c all our sales hotline </li></ul><ul><li>For additional inquires contact our technical service </li></ul><ul><li>hotline </li></ul><ul><li>For more product information go to </li></ul><ul><li>http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=69 </li></ul>

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