Capacitive touch screen having dynamic capacitance control and improved touch-sensing
First Claim
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1. A method of improving the sensing performance of a capacitive touch screen device including at least one capacitive touch pad element disposed on a surface of the capacitive touch screen, the method comprising:
- determining an electrical potential of the at least one capacitive touch pad element for detecting a user touch of the at least one capacitive touch pad element;
detecting a condition of the capacitive touch screen device that changes usable detectable range of change in capacitance for the at least one capacitive touch pad element;
selectively altering, based on the determined electrical potential of the at least one capacitive touch pad element and the detected condition, a magnitude of an electrical potential of at least one other electrically conductive structure disposed on the surface of the capacitive touch screen proximate the at least one capacitive touch pad element to alter an effective capacitance of the at least one capacitive touch pad element to thereby improve the usable detectable range of change in capacitance for the at least one capacitive touch pad element; and
subsequently detecting a user touch of the at least one capacitive touch pad element.
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Abstract
Methods and apparatus for improving the sensing performance of a capacitive touch screen sensing device. The electrical potential of conductive structures proximate capacitive touch pads of the sensing device is altered to compensate for the effect of parasitic capacitance, based on external conditions such as water on the touch screen or an intervening user worn glove. The compensation for parasitic capacitance improves the signal to noise ratio and therefore the sensing performance of the device.
22 Citations
20 Claims
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1. A method of improving the sensing performance of a capacitive touch screen device including at least one capacitive touch pad element disposed on a surface of the capacitive touch screen, the method comprising:
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determining an electrical potential of the at least one capacitive touch pad element for detecting a user touch of the at least one capacitive touch pad element; detecting a condition of the capacitive touch screen device that changes usable detectable range of change in capacitance for the at least one capacitive touch pad element; selectively altering, based on the determined electrical potential of the at least one capacitive touch pad element and the detected condition, a magnitude of an electrical potential of at least one other electrically conductive structure disposed on the surface of the capacitive touch screen proximate the at least one capacitive touch pad element to alter an effective capacitance of the at least one capacitive touch pad element to thereby improve the usable detectable range of change in capacitance for the at least one capacitive touch pad element; and subsequently detecting a user touch of the at least one capacitive touch pad element. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A capacitance touch sensing device, comprising:
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a plurality of capacitive touch sensing pads disposed on a touch sensitive surface of the capacitance touch sensing device and operatively coupled with a processor for sensing a user touch of the surface of the capacitance touch sensing device; at least one electrically conductive element disposed on the surface of the capacitance touch sensing device proximate each one of the plurality of capacitive touch sensing pads; and apparatus operative to control application of an electrical potential to a selected capacitive touch sensing pad of the capacitive touch sensing pads and to detect an external condition of the capacitive touch sensing device that changes usable detectable range of change in capacitance for the at least one capacitive touch sensing pad of the plurality of capacitive touch sensing pads, and to selectively alter, based on (i) a magnitude of an electrical potential of the capacitive touch sensing pads and (ii) the detected external condition, a magnitude of an electrical potential of the at least one electrically conductive element to compensate for attenuation of capacitive coupling of the user touch with the surface of the capacitance touch sensing device. - View Dependent Claims (9, 10, 11, 12, 13)
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14. A method of compensating for parasitic capacitance in a capacitive touch screen device including at least one capacitive touch pad element, the method comprising:
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applying an electrical potential to a selected capacitive touch pad element of the at least one capacitive touch pad element; sensing a change in natural capacitance of the selected capacitive touch pad element due to a user touch of the selected capacitive touch pad element; detecting a change in the usable detectable range of change of the natural capacitance of the selected capacitive touch pad element; selectively altering, based on the electrical potential applied to the selected capacitive touch pad element, a magnitude of an electrical potential applied to at least one capacitive touch pad element located proximate the selected capacitive touch pad element to compensate for parasitic capacitance of the at least one capacitive touch pad element located proximate the selected capacitive touch pad element; and subsequently sensing a change in natural capacitance of the selected capacitive touch pad element due to a user touch of the at least capacitive touch pad element. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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Specification