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US 11,893,175 B2Granted
Providing a driven shield during capacitance measurement
AssigneeMicrochip Technology Incorporated
InventorAnders Vinje
Life of this patent
Estimating the term…
Abstract
One or more examples of the present disclosure relate generally to systems and methods for canceling mutual capacitive effects in a capacitance measurement. Some examples relate to providing a driven shield during capacitance measurement. Some examples relate to providing such a driven shield using rail-to-rail voltage.
Claims13
A method of providing a driven shield, the method comprising:
- taking a capacitance measurement at a sensed line during a measurement phase of a measurement acquisition cycle, the measurement phase including a positive pre-charge measurement phase and a negative pre-charge measurement phase;
- applying a voltage to at least one non-sensed line during the measurement phase of the measurement acquisition cycle;
- holding the voltage at a first voltage rail during one of the positive pre-charge measurement phase and the negative pre-charge measurement phase;
- and
- varying the voltage, in a generally increasing or decreasing manner, from the first voltage rail to a second voltage rail during the other one of the positive pre-charge measurement phase and the negative pre-charge measurement phase.
2 more elements
An apparatus, comprising:
- a measurement circuit to take self-capacitance measurements of a sensed line during at least two measurement phases of a measurement acquisition cycle, the at least two measurement phases including a positive pre-charge measurement phase and a negative pre-charge measurement phase;
- and
- a driven shield circuit to generate a shield voltage at a non-sensed line during the at least two measurement phases of the measurement acquisition cycle, wherein to generate the shield voltage, the driven shield circuit to:
- hold the shield voltage at a first voltage rail during one of the positive pre-charge measurement phase or the negative pre-charge measurement phase;
- and
- change the shield voltage, in an increasing or a decreasing manner, from the first voltage rail to a second voltage rail during the other one of the positive pre-charge measurement phase or the negative pre-charge measurement phase.
3 more elements
A system, comprising:
- a touch sensor;
- a measurement circuit to take self-capacitance measurements of a sensed line of the touch sensor during at least two measurement phases of a measurement acquisition cycle, the at least two measurement phases including a positive pre-charge measurement phase and a negative pre-charge measurement phase;
- and
- a driven shield circuit to generate a shield voltage at a non-sensed line of the touch sensor during the at least two measurement phases of the measurement acquisition cycle, wherein to generate the shield voltage, the driven shield circuit to:
- hold the shield voltage at a first voltage rail during one of the positive pre-charge measurement phase or the negative pre-charge measurement phase;
- and
- change the shield voltage, in an increasing or a decreasing manner, from the first voltage rail to a second voltage rail during the other one of the positive pre-charge measurement phase or the negative pre-charge measurement phase.
4 more elements
Dependencies are inferred from the claim text.