Measuring body capacitance effect in touch sensitive device
First Claim
1. A touch sensitive device comprising:
- a touch sensor panel configured to sense an object proximate thereto;
scan logic couplable to the touch sensor panel and configured to perform a first scan sequence on the panel to measure a touch by the object at the panel during a first mode and produce a plurality of touch measurement values of a first plurality of sensing nodes; and
perform a second scan sequence on the panel to measure grounding of the object during a second mode and produce a plurality of grounding measurement values of the first plurality of sensing nodes; and
a processor configured to compensate the plurality of touch measurement values from the first scan sequence according to the plurality of grounding measurement values from the second scan sequence.
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Abstract
Measuring an effect of body capacitance in a touch sensitive device is disclosed. This effect can be caused by poor grounding of a user or other objects touching the device or of the device itself. The device can operate in a stray capacitance mode to measure a body capacitance effect and in a normal mode to detect a touch on the device. During the stray capacitance mode, the device can obtain a body capacitance measurement from the device. During the normal mode, the device can obtain a touch measurement from the device. The device can calculate a body capacitance factor based on a ratio between the body capacitance measurement and the touch measurement and use the body capacitance factor to compensate for erroneous or distorted touch output values from the device. Various components of the device can be switchably configured according to the particular mode.
23 Citations
17 Claims
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1. A touch sensitive device comprising:
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a touch sensor panel configured to sense an object proximate thereto; scan logic couplable to the touch sensor panel and configured to perform a first scan sequence on the panel to measure a touch by the object at the panel during a first mode and produce a plurality of touch measurement values of a first plurality of sensing nodes; and perform a second scan sequence on the panel to measure grounding of the object during a second mode and produce a plurality of grounding measurement values of the first plurality of sensing nodes; and a processor configured to compensate the plurality of touch measurement values from the first scan sequence according to the plurality of grounding measurement values from the second scan sequence. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method comprising:
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performing a first scan sequence on a touch sensor panel to measure a touch by an object proximate to the panel during a first mode and produce a plurality of touch measurement values of a first plurality of sensing nodes; performing a second scan sequence on the panel to measure grounding of the object during a second mode and produce a plurality of grounding measurement values of the first plurality of sensing nodes; and compensating the plurality of touch measurement values from the first scan sequence according to the plurality of grounding measurement values from the second scan sequence. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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Specification