Abstract: In one embodiment, a touch-sensitive device includes a controller, horizontal electrodes, and vertical electrodes. The touch-sensitive device further includes a first plurality of switches that couple the horizontal electrodes to a first plurality of sensors, a second plurality of switches that couple the vertical electrodes to a second plurality of sensors, and a third and fourth plurality of switches that couple the horizontal and vertical electrodes to a shield sensor. The controller is operable to perform simultaneous hovering, touch, and proximity detection by selectively controlling the first, second, third, and fourth plurality of switches. The hovering, touch, and proximity detection includes causing substantially equal voltages to be present on the horizontal and vertical electrodes while measuring capacitances using the shield sensor and either the first or second plurality of sensors.

Abstract: In one embodiment, a method includes initiating an acquisition of a first signal from an electrode of a touch sensor according to an acquisition frequency of the touch sensor. The method also includes reversing, with a controller, a polarity of the first signal to produce a second signal. The method also includes storing a first modulated signal at an end of the acquisition of the first signal, where the first modulated signal includes the second signal as modulated by one or more third-party signals during the acquisition of the first signal.

Abstract: In one embodiment, a touch sensor includes a touch screen having a plurality of electrodes and a controller. The controller is operable to detect that an object is in proximity to the touch screen by measuring capacitance values from a reference area of the touch screen, determining a reference capacitance value using the measured capacitance values from the reference area, measuring capacitance values from a main area of the touch screen, and suppressing noise from the measured capacitance values of the main area by subtracting the reference capacitance value from the measured capacitance values of the main area of the touch screen. The reference area includes two or more of the plurality of electrodes, and at least one of the electrodes of the reference area is electrically coupled to a voltage reference. The main area includes electrodes of the plurality of electrodes that are not in the reference area.

Abstract: In one embodiment, a method includes modifying an amount of charge of a capacitance of a touch sensor. The modified amount of charge resulting in a voltage at the capacitance being a first pre-determined voltage level. The method also includes applying a first pre-determined amount of charge to the capacitance. The application of the first pre-determined amount of charge to the capacitance modifying the voltage at the capacitance from the first pre-determined voltage level to a first charging voltage level. The method also includes determining a first difference between the first charging voltage level and a reference voltage level; and determining whether a touch input to the touch sensor has occurred based on the first difference.

Abstract: In one embodiment, a method includes, by a base station, communicating a challenge to a transponder through a first communication link; and establishing a second communication link with the transponder. The second communication link is a capacitive link. The method also includes receiving a first response to the challenge through the first communication link with the transponder; sampling the second communication link to detect a signal corresponding to a second response to the challenge from the transponder; receiving the second response through the second communication link; and authorizing the transponder based on the first and second responses.

Abstract: In one embodiment, a method includes initiating an acquisition of a first signal from an electrode of a touch sensor according to an acquisition frequency of the touch sensor. The method also includes reversing, with a controller, a polarity of the first signal to produce a second signal. The method also includes storing a first modulated signal at an end of the acquisition of the first signal, where the first modulated signal includes the second signal as modulated by one or more third-party signals during the acquisition of the first signal.

Abstract: In one embodiment, a controller includes one or more computer-readable non-transitory storage media embodying logic that is operable when executed to: initiate an acquisition of a first signal from an electrode of a touch sensor according to an acquisition frequency of the touch sensor, store a first modulated signal which includes a modulated form of the first signal, initiate an acquisition of a second signal from the electrode of the touch sensor according to the acquisition frequency of the touch sensor, reverse a polarity of the second signal to produce a third signal, store a second modulated signal which includes a modulated form of the third signal, generate a signal-timing waveform based on the first and second modulated signals, and retrieve information associated with a stylus from the generated signal-timing waveform.

Abstract: In one embodiment, a method includes discharging a first capacitor and discharging a set of capacitances present on a first set of lines of a touch sensor. After discharging the first capacitor and the set of capacitances, the method further includes causing charge to be transferred to the set of capacitances during a first time period. After the first time period, the method includes causing charge to be transferred to the first capacitor and the set of capacitances during a second time period. After the second time period, the voltage across the first capacitor to a first threshold is compared. The method also includes determining whether a touch was detected by the touch sensor based on comparing the voltage across the first capacitor to the first threshold.

Abstract: In one embodiment, a method includes receiving one of a number of first voltages. Each of the first voltages results at least in part from a signal applied to an electrode of each of one or more nodes of a capacitive touch sensor. The method also includes receiving a second voltage across a measurement capacitor. The second voltage results at least in part on charging the measurement capacitor through application of a pre-determined voltage. The method also includes monitoring an output voltage during the charging of the measurement capacitor. The output voltage changes state based at least in part on a comparison of the second voltage relative to the one of the first voltages.

Abstract: Two different sets of electrodes in a touch sensitive device are formed to produce an electric field gradient from one end of the electrodes to the other end when opposite ends of the electrodes are driven with different voltages. A signal measuring cycle is performed by alternately driving the ends of one set of electrodes, while using the other set of electrodes to receive signals. The roles of the sets of electrodes are then reversed, such that the set that that was driven is now used to receive signals from the other set of electrodes. Reference signals may be obtained by driving both sides of one set of electrodes, and then both sides of the other set of electrodes. The signals obtained are then used to determine the touch position on the touch sensitive device.

Abstract: In one embodiment, a method includes applying a first current to a capacitance of a touch sensor. The application of the first current to the capacitance for a first amount of time modifies the voltage at the capacitance from the reference voltage level to a first pre-determined voltage level. The method also includes applying a second current to an integration capacitor. The second current is proportional to the first current. The application of the second current to the integration capacitor for the first amount of time modifies the voltage at the integration capacitor from the reference voltage level to a first charging voltage level. The method also includes determining whether a touch input to the touch sensor has occurred based on the first charging voltage level.

Abstract: An apparatus of one embodiment includes a sensor having a plurality of electrodes and a controller having a processor and a memory. The memory includes logic operable to configure the electrodes to form a first cluster pattern having a plurality of first clusters of two or more electrodes, apply voltage to each first cluster, and determine a plurality of first values associated with a capacitance of a first cluster. The logic is further operable to configure the electrodes to form a second cluster pattern having a plurality of second clusters of two or more electrodes, apply voltage to each second cluster, and determine a plurality of second values associated with a capacitance of a second cluster. At least one second cluster is interleaved with an adjacent second cluster. The logic is further operable to determine a position of an object based at least on the second values.

Abstract: In one embodiment, an apparatus includes a sensor having a plurality of electrodes and a controller having a processor and a memory. The memory includes logic operable, when executed by the processor, to connect each electrode of a first subset of the plurality of electrodes, apply voltage to the first subset, and determine a first value associated with a capacitance of the first subset. Based at least on the first value, the logic is further operable to connect each electrode of a second subset of the plurality of electrodes, the second subset having fewer electrodes than the first subset, apply voltage to the second subset, and determine a second value associated with a capacitance of the second subset.

Abstract: In one embodiment, a touch-sensitive device includes a controller, horizontal electrodes, and vertical electrodes. The touch-sensitive device further includes a first plurality of switches that couple the horizontal electrodes to a first plurality of sensors, a second plurality of switches that couple the vertical electrodes to a second plurality of sensors, and a third and fourth plurality of switches that couple the horizontal and vertical electrodes to a shield sensor. The controller is operable to perform simultaneous hovering, touch, and proximity detection by selectively controlling the first, second, third, and fourth plurality of switches. The hovering, touch, and proximity detection includes causing substantially equal voltages to be present on the horizontal and vertical electrodes while measuring capacitances using the shield sensor and either the first or second plurality of sensors.

Abstract: In one embodiment, a touch sensor includes a touch screen having a plurality of electrodes and a controller. The controller is operable to detect that an object is in proximity to the touch screen by measuring capacitance values from a reference area of the touch screen, determining a reference capacitance value using the measured capacitance values from the reference area, measuring capacitance values from a main area of the touch screen, and suppressing noise from the measured capacitance values of the main area by subtracting the reference capacitance value from the measured capacitance values of the main area of the touch screen. The reference area includes two or more of the plurality of electrodes, and at least one of the electrodes of the reference area is electrically coupled to a voltage reference. The main area includes electrodes of the plurality of electrodes that are not in the reference area.

Abstract: In one embodiment, a method includes applying a first current to a capacitance of a touch sensor. The application of the first current to the capacitance for a first amount of time modifies the voltage at the capacitance from the reference voltage level to a first pre-determined voltage level. The method also includes applying a second current to an integration capacitor. The second current is proportional to the first current. The application of the second current to the integration capacitor for the first amount of time modifies the voltage at the integration capacitor from the reference voltage level to a first charging voltage level. The method also includes determining whether a touch input to the touch sensor has occurred based on the first charging voltage level.

Abstract: In one embodiment, a method includes applying a first current to a capacitance of a touch sensor. The application of the first current to the capacitance for a first amount of time modifies the voltage at the capacitance from the reference voltage level to a first pre-determined voltage level. The method also includes applying a second current to an integration capacitor. The second current is proportional to the first current. The application of the second current to the integration capacitor for the first amount of time modifies the voltage at the integration capacitor from the reference voltage level to a first charging voltage level. The method also includes determining whether a touch input to the touch sensor has occurred based on the first charging voltage level.

Abstract: Two different sets of electrodes in a touch sensitive device are formed to produce an electric field gradient from one end of the electrodes to the other end when opposite ends of the electrodes are driven with different voltages. A signal measuring cycle is performed by alternately driving the ends of one set of electrodes, while using the other set of electrodes to receive signals. The roles of the sets of electrodes are then reversed, such that the set that that was driven is now used to receive signals from the other set of electrodes. Reference signals may be obtained by driving both sides of one set of electrodes, and then both sides of the other set of electrodes. The signals obtained are then used to determine the touch position on the touch sensitive device.

Abstract: Apparatus and methods are described for selecting which of a plurality of simultaneously activated keys in a keyboard based on an array of capacitive sensors is a key intended for selection by a user. Combinations of keys which are commonly activated simultaneously when a user intends to select a single key are identified and associated with the single keys most likely to give rise to the identified combinations during normal use of the keyboard. In use, an observed combination of simultaneously activated keys is compared with predefined combinations of keys corresponding to those identified as being commonly activated simultaneously. If the combination of activated keys matches one of the predefined combinations, the most likely intended key associated with the matched one of the predefined combination of keys is taken to be most likely intended key.

Abstract: In one embodiment, a method includes applying a first current to a capacitance of a touch sensor. The application of the first current to the capacitance for a first amount of time modifies the voltage at the capacitance from the reference voltage level to a first pre-determined voltage level. The method also includes applying a second current to an integration capacitor. The second current is proportional to the first current. The application of the second current to the integration capacitor for the first amount of time modifies the voltage at the integration capacitor from the reference voltage level to a first charging voltage level. The method also includes determining whether a touch input to the touch sensor has occurred based on the first charging voltage level.