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How does surface capacitive touchscreen work in detail?

  1. Sep 30, 2015 #1
    It's pretty easy to find the "working principle" of surface capacitive touchscreen like http://www.elotouch.com/Technologies/SurfaceCapacitive/howitworks.asp [Broken]

    Roughly speaking, I know that

    • A surface capacitive touchscreen has a conductive layer to which some electrodes are attached
    • The electrodes apply voltage across the layer
    • When some conductive material, e.g. finger touches the layer a portion of current is drawn yielding numbers' changes in the sensors attached to the electrodes
    • According to the numbers read from sensors, one calculates the touch location

    Here're the questions:
    • Should the electrodes apply DC or AC signals to the layer?
    • How is the "conductive layer" modeled, i.e. is it regarded as a 2D conductive plane ? Or is it regarded as a 3D conductive block? In either case, how to calculate or approximately guess the charge/voltage/current distribution when the layer is idle/touched?
    • What are proper sensors to attach to the electrodes, e.g. voltage metres or current metres or sth else? Why?
    Last edited by a moderator: May 7, 2017
  2. jcsd
  3. Oct 5, 2015 #2
    Thanks for the post! This is an automated courtesy bump. Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post?
  4. Oct 6, 2015 #3
    Thanks for the reminder. However I'm not sure how to better rephrase the problem because the quantitative details of touch point for surface capacitance is also mysterious to me and I've written the qualitative information that I know by far :(

    I'm reading relevant papers/patents and will add more information as soon as possible.
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