Multipoint touch surface controller
First Claim
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1. A charge amplifier for detecting changes in capacitance at one or more touch nodes of a touch sensor panel, comprising:
- an operational amplifier having a non-inverting input terminal, an inverting input terminal coupled to the one or more touch nodes, and an output terminal;
a feedback capacitor connected between the output terminal and the inverting input terminal, wherein the feedback capacitor is programmable to take on a range of values; and
a feedback resistor connected between the output terminal and the inverting input terminal, wherein the feedback resistor is programmable to take on a range of values,wherein a capacitance of the feedback capacitor is set on a per-node basis using a value having a component adjustable on a row by row basis.
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Abstract
A multipoint touch surface controller is disclosed herein. The controller includes an integrated circuit including output circuitry for driving a capacitive multi-touch sensor and input circuitry for reading the sensor. Also disclosed herein are various noise rejection and dynamic range enhancement techniques that permit the controller to be used with various sensors in various conditions without reconfiguring hardware.
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Citations
22 Claims
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1. A charge amplifier for detecting changes in capacitance at one or more touch nodes of a touch sensor panel, comprising:
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an operational amplifier having a non-inverting input terminal, an inverting input terminal coupled to the one or more touch nodes, and an output terminal; a feedback capacitor connected between the output terminal and the inverting input terminal, wherein the feedback capacitor is programmable to take on a range of values; and a feedback resistor connected between the output terminal and the inverting input terminal, wherein the feedback resistor is programmable to take on a range of values, wherein a capacitance of the feedback capacitor is set on a per-node basis using a value having a component adjustable on a row by row basis. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for detecting changes in capacitance at one or more touch nodes of a touch sensor panel, comprising:
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transmitting a signal indicating the changes in capacitance at one or more of the touch nodes to a charge amplifier comprising an operational amplifier having a non-inverting input terminal and an inverting input terminal coupled to the one or more touch nodes; providing, by the charge amplifier, virtual ground charge amplification of touch nodes sense lines to detect the changes in capacitance at the one or more touch nodes; setting a feedback capacitance of the charge amplifier on a per-node basis using a value having a component adjustable on a row by row basis; and programmably optimizing a dynamic range of the virtual ground charge amplification. - View Dependent Claims (8, 9)
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10. A touch sensor panel, comprising:
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a plurality of touch nodes; and one or more charge amplifiers coupled to the plurality of touch nodes for detecting changes in capacitance at each of the plurality of touch nodes due to a touch by receiving a signal indicating the changes in capacitance at one or more of the touch modes, each of the charge amplifier comprising an operational amplifier having a non-inverting input terminal and an inverting input terminal coupled to the one or more touch nodes; wherein the one or more charge amplifiers are configurable on a per-node basis using a value having a component adjustable on a row by row basis to account for variations at the touch sensor panel by setting a feedback capacitance of each of the one or more charge amplifiers based on node to which it is attached. - View Dependent Claims (11, 12, 13, 14)
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15. A method for compensating a touch sensor panel having a plurality of touch nodes, comprising:
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coupling one or more charge amplifiers to the plurality of touch nodes in the touch sensor panel to detect changes in capacitance due to a touch at each of the touch nodes, each of the charge amplifiers comprising an operational amplifier having a non-inverting input terminal and an inverting input terminal coupled to the one or more touch nodes; receiving by the one or more charge amplifiers a signal indicating the changes in capacitance at one or more of the touch nodes; and configuring the one or more charge amplifiers on a per-node basis using a value having a component adjustable on a row by row basis to compensate for variations at the touch sensor panel by setting a feedback capacitance of each of the one or more charge amplifiers based on node to which it is attached. - View Dependent Claims (16, 17, 18)
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19. A computing device including a touch sensor panel, the touch sensor panel comprising:
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a plurality of touch nodes; and one or more charge amplifiers coupled to the plurality of touch nodes for detecting changes in capacitance at each of the plurality of touch nodes due to a touch by receiving a signal indicating the changes in capacitance at one or more of the touch modes, each of the charge amplifier comprising an operational amplifier having a non-inverting input terminal and an inverting input terminal coupled to the one or more touch nodes; wherein the one or more charge amplifiers are configurable on a per-node basis using a value having a component adjustable on a row by row basis to account for variations at the touch sensor panel by setting a feedback capacitance of each of the one or more charge amplifiers based on node to which it is attached.
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20. An apparatus for detecting changes in capacitance at one or more touch nodes of a touch sensor panel, comprising:
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means for transmitting a signal indicating the changes in capacitance at one or more of the touch nodes to a charge amplifier comprising an operational amplifier having a non-inverting input terminal and an inverting input terminal coupled to the one or more touch nodes; means for providing, by the charge amplifier, virtual ground charge amplification of touch nodes sense lines to detect the changes in capacitance at the one or more touch nodes; means for setting a feedback capacitance of the charge amplifier on a per-node basis using a value having a component adjustable on a row by row basis; and means for programmably optimizing a dynamic range of the virtual ground charge amplification. - View Dependent Claims (21, 22)
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Specification