Driven shield for shaping an electric field of a touch sensor
First Claim
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1. An apparatus comprising:
- an electrode;
a shield; and
a controller configured to;
transmit a first drive signal to the electrode, the electrode generating a first electric field in response to receiving the first drive signal, a first portion of the first electric field extending toward the shield and a second portion of the first electric field extending away from the shield;
transmit a second drive signal to the shield, the shield generating a second electric field in response to receiving the second drive signal, a portion of the second electric field extending toward the electrode and reshaping the first portion of the first electric field such that first electric field lines of the first portion of the first electric field are shorter than second electric field lines of the second portion of the first electric field;
equalize a strength of the first electric field generated by the electrode and a strength of the second electric field generated by the shield by adjusting an amplitude of the second drive signal transmitted to the shield to compensate for absorption of the second electric field by a conductive surface, wherein adjusting the amplitude of the second drive signal further reshapes the first portion of the first electric field;
measure, after transmitting the first drive signal to the electrode and the adjusted second drive signal to the shield, a capacitance associated with the electrode; and
determine, based on the capacitance, whether a touch or proximity input has occurred;
wherein the amplitude of the adjusted second drive signal differs from an amplitude of the first drive signal.
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Abstract
In one embodiment, a method comprises generating, by a control unit, a first drive signal and a second drive signal. The method further includes emitting, by a touch sensor, a first electric field that extends in a plurality of directions in response to reception of the first drive signal. The method also includes attenuating, by a conductive shield, a portion of the first electric field that extends from the touch sensor towards the conductive shield by generating a second electric field in response to reception of the second drive signal.
39 Citations
17 Claims
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1. An apparatus comprising:
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an electrode; a shield; and a controller configured to; transmit a first drive signal to the electrode, the electrode generating a first electric field in response to receiving the first drive signal, a first portion of the first electric field extending toward the shield and a second portion of the first electric field extending away from the shield; transmit a second drive signal to the shield, the shield generating a second electric field in response to receiving the second drive signal, a portion of the second electric field extending toward the electrode and reshaping the first portion of the first electric field such that first electric field lines of the first portion of the first electric field are shorter than second electric field lines of the second portion of the first electric field; equalize a strength of the first electric field generated by the electrode and a strength of the second electric field generated by the shield by adjusting an amplitude of the second drive signal transmitted to the shield to compensate for absorption of the second electric field by a conductive surface, wherein adjusting the amplitude of the second drive signal further reshapes the first portion of the first electric field; measure, after transmitting the first drive signal to the electrode and the adjusted second drive signal to the shield, a capacitance associated with the electrode; and determine, based on the capacitance, whether a touch or proximity input has occurred; wherein the amplitude of the adjusted second drive signal differs from an amplitude of the first drive signal. - View Dependent Claims (2, 3, 4, 5, 6)
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7. One or more non-transitory computer-readable storage media embodying logic that is operable when executed to:
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transmit a first drive signal to an electrode, the electrode generating a first electric field in response to receiving the first drive signal, a first portion of the first electric field extending toward a shield and a second portion of the first electric field extending away from the shield; transmit a second drive signal to the shield, the shield generating a second electric field in response to receiving the second drive signal, a portion of the second electric field extending toward the electrode and reshaping the first portion of the first electric field such that first electric field lines of the first portion of the first electric field are shorter than second electric field lines of the second portion of the first electric field; equalize a strength of the first electric field generated by the electrode and a strength of the second electric field generated by the shield by adjusting an amplitude of the second drive signal transmitted to the shield to compensate for absorption of the first electric field by a conductive surface, wherein adjusting the amplitude of the second drive signal further reshapes the first portion of the first electric field; measure, after transmitting the first drive signal to the electrode and the adjusted second drive signal to the shield, a capacitance associated with the electrode; and determine, based on the capacitance, whether a touch or proximity input has occurred; wherein the amplitude of the adjusted second drive signal differs from an amplitude of the first drive signal. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A method, comprising:
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transmitting a first drive signal to an electrode, the electrode generating a first electric field in response to receiving the first drive signal, a first portion of the first electric field extending toward a shield and a second portion of the first electric field extending away from the shield; transmitting a second drive signal to the shield, the shield generating a second electric field in response to receiving the second drive signal, a portion of the second electric field extending toward the electrode and reshaping the first portion of the first electric field such that first electric field lines of the first portion of the first electric field are shorter than second electric field lines of the second portion of the first electric field; equalizing a strength of the first electric field generated by the electrode and a strength of the second electric field generated by the shield by adjusting an amplitude of the second drive signal transmitted to the shield to compensate for absorption of the second electric field by a conductive surface, wherein adjusting the amplitude of the second drive signal further reshapes the first portion of the first electric field; measuring, after transmitting the first drive signal to the electrode and the adjusted second drive signal to the shield, a capacitance associated with the electrode; and determining, based on the capacitance, whether a touch or proximity input has occurred; wherein the amplitude of the adjusted second drive signal differs from an amplitude of the first drive signal. - View Dependent Claims (14, 15, 16, 17)
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Specification