Abstract: Examples are disclosed that relate to methods and computing devices for determining a distance of an input device from a surface of a computing device. In one example, a method comprises receiving a plurality of input device signals via the input device. A portion of the input device signals are used to determine an effective voltage of the input device. Adjusted input device signals are generated by adjusting another portion of input device signals using the effective voltage of the input device. The method further comprises providing the adjusted input device signals as an input to a distance model, and receiving and outputting the distance of the input device from the surface of the computing device.

Abstract: A touch-sensitive device, including a capacitive touch-sensitive surface including an array of electrodes. The touch-sensitive device may further include processing circuitry configured to determine a detected position at which a stylus contacts or hovers above the capacitive touch-sensitive surface. The processing circuitry may determine, based at least in part on the detected position, a first and second electrode set of the electrodes included in the array. The detected position may be located proximate to one or more first row electrodes and/or one or more first column electrodes included in the first electrode set. The second electrode set may include a plurality of second row electrodes and a plurality of second column electrodes not included in the first electrode set. The touch-sensitive device may further include a driving circuit configured to transmit a first driving signal to the first electrode set and a second driving signal to the second electrode set.

Abstract: A touch-sensitive display device includes a touch sensor having a plurality of display electrodes and control logic coupled to the plurality of display electrodes. The control logic is configured to receive, for each of a plurality of stylus electrodes of an active stylus interacting with the touch-sensitive display device, a spatial capacitance measurement over the touch sensor for that stylus electrode. Relative to the touch sensor, and based on spatial capacitance measurements of the stylus electrodes, the control logic is configured to determine (i) a tip position of the active stylus, (ii) a tilt parameter of the active stylus, and (iii) a twist parameter of the active stylus.

Abstract: Examples are disclosed herein that relate to various operational modes of a capacitive touch sensor. One example provides a touch-sensitive input device comprising receive circuitry, a capacitive touch sensor having a plurality of portions, and a controller. The controller is configured to, responsive to not detecting a finger or a pen, operate the touch sensor in a locating mode by successively driving each portion with a fixed DC voltage and multiplexing the portion to the receive circuitry in a predefined sequence, and responsive to detecting the pen, operate the touch sensor in a tracking mode by driving a selected portion with the fixed DC voltage and multiplexing the selected portion to the receive circuitry to track the pen, the selected portion selected based on a detected location of the pen relative to the touch sensor and being varied as the detected location changes.

Abstract: An active stylus includes a stylus electrode, receive circuitry, and transmit circuitry. The stylus electrode is configured to capacitively couple with one or more electrodes of a capacitance-based touch sensor of a touch-sensitive device. The receive circuitry is operatively coupled to the stylus electrode and configured to receive a synchronization waveform from the touch-sensitive device. The transmit circuitry is operatively coupled to the stylus electrode and configured to, upon receiving the synchronization waveform, transmit stylus information to the touch-sensitive device according to a communication frame including a first set of sub-frames and a second set of sub-frames. The transmit circuitry is configured to transmit a first waveform during the first set, if the active stylus is hovering, transmit the first waveform during the second set, and if the active stylus is not hovering, transmit one or more additional waveforms during the second set.

Abstract: A touch-sensitive display device includes a capacitance-based touch sensor including a plurality of electrodes, a display including a plurality of pixels, an image source configured to output image frames at a video frame rate, and a controller. The controller is configured to perform capacitance measurements on the capacitance-based touch sensor in capacitance-measurement intervals of a touch-sensing frame, and perform display-write operations on the display to write each image frame to the display in display-write intervals of the touch-sensing frame that do not temporally overlap with the capacitance-measurement intervals of the touch-sensing frame. The controller is configured repeat the touch-sensing frame at a fixed touch-sensing frame rate that is different than the video frame rate.

Abstract: Examples are disclosed herein that relate to various operational modes of a capacitive touch sensor. One example provides a touch-sensitive input device comprising receive circuitry, a capacitive touch sensor having a plurality of portions, and a controller. The controller is configured to, responsive to not detecting a finger or a pen, operate the touch sensor in a locating mode by successively driving each portion with a fixed DC voltage and multiplexing the portion to the receive circuitry in a predefined sequence, and responsive to detecting the pen, operate the touch sensor in a tracking mode by driving a selected portion with the fixed DC voltage and multiplexing the selected portion to the receive circuitry to track the pen, the selected portion selected based on a detected location of the pen relative to the touch sensor and being varied as the detected location changes.

Abstract: A touch-sensitive display device includes a touch sensor having a plurality of display electrodes and control logic coupled to the plurality of display electrodes. The control logic is configured to receive, for each of a plurality of stylus electrodes of an active stylus interacting with the touch-sensitive display device, a spatial capacitance measurement over the touch sensor for that stylus electrode. Relative to the touch sensor, and based on spatial capacitance measurements of the stylus electrodes, the control logic is configured to determine (i) a tip position of the active stylus, (ii) a tilt parameter of the active stylus, and (iii) a twist parameter of the active stylus.

Abstract: A touch-sensitive in-cell display device includes an active matrix of row conductors and column conductors, a plurality of pixels, and a controller. Each pixel is connected to a row conductor and a column conductor at a different intersection of the active matrix and each pixel is connected to a common electrode. The controller is configured to perform a display-write operation on a pixel at a first time at least by applying different voltages to the row conductor, the column conductor, and the common electrode connected to the first pixel, and perform an electrostatic measurement at a second time at least by applying a same common-mode excitation voltage to the row conductor, the column conductor, and the common electrode connected to the pixel, while measuring a current through a designated conductor.

Abstract: A touch-sensitive device includes a touch sensor including a plurality of electrodes and receive circuitry configured to interpret a response on one or more electrodes of the plurality of electrodes based on stylus waveforms being driven on a stylus electrode of an active stylus. The touch-sensitive device is configured to correlate the stylus waveforms with one or more reference waveforms to produce correlation magnitudes; The touch-sensitive device is further configured to map each correlation magnitude to a demodulation symbol selected from a plurality of demodulation symbols of a one-dimensional, non-uniform constellation. Each demodulation symbol encodes multiple data bits. The touch-sensitive device is further configured to decode the mapped demodulation symbols to determine a plurality of data bits of stylus information of the active stylus.

Abstract: Examples are disclosed herein that relate to reducing noise in received signals. An example provides a method comprising receiving, via one or more electrodes of an input device, a capacitive signal, for each of two or more reference sequences designed for a respective capacitive signal condition, correlating the capacitive signal with the reference sequence, and identifying a particular one of the two or more reference sequences that produced a highest noise immunity when correlated with the capacitive signal. The method may further comprise correlating the identified reference sequence with a subsequent capacitive signal to thereby receive information in the subsequent capacitive signal regarding an input device condition.

Abstract: A touch-sensitive display device includes a touch sensor having a plurality of display electrodes and control logic coupled to the plurality of display electrodes. The control logic is configured to receive, for each of a plurality of stylus electrodes of an active stylus interacting with the touch-sensitive display device, a spatial capacitance measurement over the touch sensor for that stylus electrode. Relative to the touch sensor, and based on spatial capacitance measurements of the stylus electrodes, the control logic is configured to determine (i) a tip position of the active stylus, (ii) a tilt parameter of the active stylus, and (iii) a twist parameter of the active stylus.

Abstract: An active stylus includes a stylus electrode configured to electrostatically couple with one or more electrodes of a display device having a capacitance-based touch sensor, transmit logic configured to drive the stylus electrode with a synchronization waveform that is configured, via interpreting a response on one or more electrodes of a first display device, to enable the first display device to become time synchronized with the active stylus in a stylus-initiated synchronization mode, receive logic configured to interpret a response on the stylus electrode caused by a synchronization waveform being driven on one or more electrodes of a second display device, to enable the active stylus to become time synchronized with the second display device in a display-initiated synchronization mode, and a controller configured, in response to detection of a condition, to cause the active stylus to switch from one of the synchronization modes to the other.

Abstract: The presently disclosed technology uses predefined handwriting characteristics to create and/or refine a stylus position interpolation function over time to provide more accurate and adaptive renderings of the user's handwriting on a touch screen. As the presently disclosed technology is performed on a specific device and uses data collected from one or more specific users, it adapts the stylus position interpolation function for any device-specific or user-specific variations. Further, as the stylus position interpolation function adapts iteratively over time, it may not converge and continues to adapt as the device ages, the user's habits change, or identify of the user changes, and environmental conditions of the device change.

Abstract: Examples are disclosed herein that relate to communication between a capacitive touch sensor and an active stylus. An example provides an active stylus comprising an electrode tip, and receive circuitry coupled to the electrode tip. The receive circuitry may be configured to receive a capacitive signal from a touch sensor through the electrode tip, determine which of two or more drive signals produced by respective regions of the touch sensor most strongly influenced the capacitive signal, each drive signal being associated with a different operating mode, and configure one or both of the active stylus and the touch sensor to operate in the operating mode associated with the determined drive signal.

Abstract: A touch-sensitive device includes a capacitance-based touch sensor, drive circuitry configured to drive touch sensor electrodes with a synchronization waveform to enable an active stylus to become time synchronized with the touch-sensitive device, and receive circuitry configured to determine a position of the active stylus based on electrostatically receiving a first waveform from the active stylus. Depending on when the touch-sensitive device receives the first waveform from the active stylus, the touch-sensitive device interprets the first waveform differently to determine a position of the active stylus or determine that the active stylus is hovering. In either case, the same waveform is used to communicate different information about the active stylus to the touch-sensitive device.

Abstract: Embodiments are disclosed that relate to touch input detection in a touch sensor. One example provides a method comprising establishing a first reference sequence, starting with a first set of candidate reference sequences each differing from the first reference sequence, reducing the first set of candidate reference sequences by applying a rule set to the first set to derive a relatively smaller second set of candidate reference sequences, for each candidate reference sequence in the second set of candidate reference sequences, calculating a touch detection performance score of a combined reference sequence, and configuring at least a portion of a receive circuit to correlate signals to at least one of the touch detection conditions by using the first reference sequence in a combined correlation operation with at least a selected candidate reference sequence from the second set of candidate reference sequences.

Abstract: A touch-sensitive display device includes a touch sensor, drive circuitry and receive circuitry. The touch sensor has a matrix of row electrodes and column electrodes. The drive circuitry drives the row electrodes during a touch-sensing frame to influence electrical conditions on the column electrodes. The receive circuitry, during the touch-sensing frame, for each row electrode of the matrix, measures a capacitance of each column electrode while the row electrode is being driven, for each of a plurality of different sections of column electrodes of the matrix, performs local analysis of the measured capacitances of the column electrodes of the section to estimate a row-specific noise capacitance for each column electrode, and determines a touch input based on a difference between the measured capacitance of the column electrode while the row electrode is being driven and the estimated row-specific noise capacitance of the column electrode.

Abstract: A touch-sensitive display device includes a touch sensor having a plurality of touch-sensing electrodes and control logic coupled to the plurality of touch-sensing electrodes. The control logic is configured to, in a non-reference time frame and based on a spatial capacitance measurement received for a first stylus electrode of an active stylus, estimate a non-reference time frame location of the first stylus electrode relative to the plurality of touch-sensing electrodes. In a reference time frame, based on a spatial capacitance measurement received for a second stylus electrode of the active stylus, a reference time frame location of the second stylus electrode is estimated. Based on an estimated velocity of the first stylus electrode, the non-reference location of the first stylus electrode is velocity corrected to give a reference time frame location of the first stylus electrode.

Abstract: Examples are described for touch-sensitive displays in which ground references for associated electronics are isolated from one another. In one example, a touch-sensitive display includes a display panel, and a touch sensor, the touch sensor including a receive electrode, the touch sensor including a transmit electrode, the receive electrode and the transmit electrode overlaying the display panel, and wherein a ground reference of the receive and/or the transmit electrode is isolated from a ground reference of the display panel, thereby creating a transmission-inhibiting communication boundary between the display panel and the touch sensor, the touch sensor communicatively connected to the display panel so as to exchange data between ground domains separated by the boundary.