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US 9,069,399 B2Granted
Gain correction for fast panel scanning
AssigneeCypress Semicoductor Corporation
InventorsYuriy Boychuk, David P. Finch, Oleksandr Karpin, Vasyl Mandziy
Life of this patent
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Abstract
A method calculates a correction factor for one or more of capacitance sensors and generates a current from a mutual capacitance of one of the capacitance sensors. The method applies the correction factor to the generated current to generate a corrected current and converts the corrected current to a digital value. The method determines a position of one or more conductive objects in proximity to the one or more capacitance sensors based on the digital value.
Claims18
A method comprising:
- generating a correction factor for at least one of a plurality of capacitance sensors of a mutual capacitance touch sensing array, wherein the calculating a correction factor comprises
- converting a second mutual capacitance of the plurality of capacitance sensors to a second digital value at a first transmit frequency,
- converting a third mutual capacitance of the plurality of capacitance sensors to a third digital value at a second transmit frequency,
- comparing the second and third digital values, and
- calculating the correction factor based on the comparison of the second and third digital values;
- generating a current derived from a first mutual capacitance of the at least one of the plurality of capacitance sensors;
- applying the correction factor to the generated current to generate a corrected current;
- converting the corrected current to a first digital value;
- and
- determining a position of at least one conductive object in proximity to the plurality of capacitance sensors based on the digital value.
7 more elements
An apparatus comprising:
- a plurality of mutual capacitance touch sensors;
- signal transmit circuitry coupled to each of the plurality of mutual capacitance sensors, the transmit circuit configurable to generate a plurality of signals, the plurality of signals having different frequencies;
- signal receive circuitry coupled to each of the plurality of mutual capacitance sensors, the receive circuitry configurable to convert a current derived from the transmit signal and a first mutual capacitance to a first digital value representative of the transmit signal and the mutual capacitance of the sensor;
- and
- processing circuitry configurable to:
- receive the digital value,
- apply a correction factor to the current generated by the transmit signal and the mutual capacitance of the at least one of the plurality of capacitance sensors, the correction factor generated by:
- converting a second mutual capacitance at a first transmit frequency to a second digital value
- converting a third mutual capacitance at a second transmit frequency to a third digital value,
- comparing the second and third digital values, and
- calculating the correction factor based on the comparison of the second and third digital values, and
- determine a position of at least one conductive object in proximity to the plurality of capacitance sensors based on a corrected current from the generated current and the correction factor.
9 more elements
A system comprising:
- a mutual capacitance touch sensing array configurable to be driven at a plurality of frequencies;
- mutual capacitance measurement circuitry configured to convert a current derived from the plurality of frequencies and a first mutual capacitance of each of a plurality of nodes of the mutual capacitance sensing array to digital values representative of the first mutual capacitance of each of the plurality of nodes of the mutual capacitance sensing array;
- and
- processing circuitry configurable to:
- receive the digital value representative of the transmit signal and the mutual capacitance of the sensor,
- apply a correction factor to the generated current derived from the plurality of frequencies and the at least one of the plurality of capacitance sensors to produce a corrected current, the correction factor generated by:
- converting a second mutual capacitance at a first transmit frequency to a second digital value,
- converting a third mutual capacitance at a second transmit frequency to a third digital value,
- comparing the second and third digital values, and
- calculating the correction factor based on the comparison of the second and third digital values, and
- determine a position of at least one conductive object in proximity to the plurality of capacitance sensors based on the digital values from the corrected current.
8 more elements
Dependencies are inferred from the claim text.