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genxium
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It's pretty easy to find the "working principle" of surface capacitive touchscreen like http://www.elotouch.com/Technologies/SurfaceCapacitive/howitworks.asp
Roughly speaking, I know that
Here're the questions:
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?
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