Negative touch recovery for mutual capacitance scanning systems
AssigneeParade Technologies, Ltd.
InventorDennis Wavomba
Life of this patent
Estimating the term…
Abstract
A device stores running baseline measurements and initial baseline measurements for a plurality of touch sensors. The device repeatedly takes measurements from the touch sensors during device operation, and counts a number of positive transitions of the measurements, and counts a number of negative transitions of the measurements, the transitions relative to the stored initial baseline measurements. The device re-initializes the stored initial baseline measurements if and only if the count of negative transitions differs from the count of positive transitions by a predetermined amount (a “negative touch state”).
Claims19
A mobile communication device, comprising:
- a touch-sensitive surface having a circuit configured for:
- storing running baseline capacitance measurements and initial baseline capacitance measurements for a plurality of touch sensors of the touch-sensitive surface;
- repeatedly taking capacitance measurements from the touch sensors during device operation, counting a number of positive transitions of the measurements, and counting a number of negative transitions of the measurements, wherein each positive transition includes capacitance measurements exceeding the stored initial baseline measurements by a predetermined first threshold amount, each negative transition includes capacitance measurements falling below the stored initial baseline measurements by a predetermined second threshold amount, and the predetermined first and second threshold amounts are specified independently;
- determining that the count of negative transitions differs from the count of positive transitions by a predetermined amount;
- and
- in response to determining that the count of negative transitions differs from the count of positive transitions by the predetermined amount, re-initializing the stored initial baseline capacitance measurements.
A device comprising a touch-sensitive surface having a circuit configured for:
- storing running baseline capacitance measurements and initial baseline capacitance measurements for a plurality of touch sensors;
- repeatedly taking capacitance measurements from the touch sensors during device operation, counting a number of positive transitions of the measurements, and counting a number of negative transitions of the measurements, wherein each positive transition includes capacitance measurements exceeding the stored initial baseline measurements by a predetermined first threshold amount, each negative transition includes capacitance measurements falling below the stored initial baseline capacitance measurements by a predetermined second threshold amount, and the predetermined first and second threshold amounts are specified independently;
- and
- detecting a negative touch state in which the count of negative transitions differs from the count of positive transitions by a predetermined amount;
- and
- in response to detecting the negative touch state, re-initializing the stored initial baseline capacitance measurements.
A method performed at a touch-sensitive device with a plurality of touch sensors, comprising:
- upon transitioning the touch-sensitive device from a sleep state to an active state, scanning the plurality of touch sensors to establish baseline capacitance measurements;
- after transitioning the touch-sensitive device from the sleep state to the active state:
- storing running baseline capacitance measurements and initial baseline capacitance measurements for the plurality of touch sensors;
- repeatedly taking capacitance measurements from the touch sensors during operation of the touch-sensitive device, counting a number of positive transitions of the capacitance measurements, and counting a number of negative transitions of the capacitance measurements, wherein each positive transition includes capacitance measurements exceeding the stored initial baseline capacitance measurements by a predetermined first threshold amount, each negative transition includes capacitance measurements falling below the stored initial baseline capacitance measurements by a predetermined second threshold amount, and the first and second threshold amounts are asymmetrical;
- determining that the count of negative transitions differs from the count of positive transitions by a predetermined amount;
- and
- in response to determining that the count of negative transitions differs from the count of positive transitions by a predetermined amount, re-initializing the stored initial baseline capacitance measurements.
Dependencies are inferred from the claim text.