Abstract:
A video display includes a video display panel and a video display drive circuit configured to control a display on condition. A touch screen includes a touch screen panel (mounted on top of the video display panel) and a touch panel control and sense circuit configured to operate the touch screen panel in a self-capacitance mode. The touch panel control and sense circuit includes sense drive circuits configured to generate sense drive signals for application to sense lines of the touch screen panel. A controller controls actuation of the sense drive circuits so that the sense drive signals are synchronized to the display on condition. In an implementation, the leading edges of the sense drive signals are synchronized to the display on condition. In another implementation, a window is synchronized to the display on condition and the leading edges of the sense drive signals exhibit jitter within the window.
Abstract:
A capacitive touch system generates data indicative of sensed capacitance measured at capacitive sensing nodes of a capacitive touch panel. A signal processing circuit is coupled to receive the data indicative of sensed capacitance from the capacitive touch system. The signal processing circuit operates to fit a parabolic curve to the data indicative of sensed capacitance. A sharpness of the fit parabolic curve is indicative of whether touch versus hover interaction with the capacitive touch panel. A touch detection threshold is as a function of the determined sharpness. The set touch detection threshold is then applied against the data indicative of sensed capacitance in order to make a touch detection.
Abstract:
A device includes an analog to digital converter configured to convert voltages into a digital signal by sampling the voltages at a fixed sampling time; a first multiplier configured to multiply the digital signal with in-phase coefficients, the in-phase coefficients generated to produce a demodulated in-phase signal at a demodulation signal frequency; a first adder configured accumulate the demodulated in-phase signal to output in-phase magnitude values; a second multiplier configured to multiply the digital signal with quadrature coefficients, the quadrature coefficients generated to produce a demodulated quadrature signal at the demodulation signal frequency; and a second adder configured to accumulate the demodulated quadrature signal to output quadrature magnitude values.
Abstract:
A touch-screen-controller (TSC) performs mutual sensing to acquire touch strength values from a touch matrix formed by capacitively intersecting conductive lines. For each line, the TSC generates an emulated self capacitance value from an associated touch strength value based upon a position of that line compared to a location on the touch matrix adjacent to which a first touch type is expected to occur, and determines presence of the first touch type adjacent to the touch matrix based upon the emulated values. The emulated values for each conductive line may be weighted based upon its closeness to the location where the first touch type is expected to occur. The weighting may be zero if its associated conductive line is outside of the location where the first touch type is expected to occur, and may be one if inside of the location where the first touch type is expected to occur.
Abstract:
An electronic device includes a flexible substrate. The flexible substrate includes a first portion having a plurality of first conductive lines formed thereon, a second portion having a plurality of second conductive lines formed thereon, and an intermediate portion mechanically coupling the first portion to the second portion. The intermediate portion is configured to permit folding so that the first and second portions can be arranged back-to-back or face-to-face such that plurality of the second conductive lines and plurality of first conductive lines are oriented so as to cross one another to thereby form a capacitive sensing panel. A single connector is mechanically coupled to the first portion or the second portion, and electrically coupled to the first portion and the second portion but not electrically coupling the first portion to the second portion.
Abstract:
An electronic device may include a touchscreen having sensing capacitors, and readout circuitry. The readout circuitry may be configured to accumulate a sample set from each sensing capacitor, divide the sample set into sample subsets, remove a given sample subset when the given sample subset exceeds a threshold, and process remaining sample subsets for touch input.
Abstract:
A charge sensing circuit generates a voltage in a sensing period that is indicative of sensed charge. The generated voltages are accumulated by an accumulator circuit over a number of sensing periods. A noise detection circuit senses when the voltage generated by the charge sensing circuit is outside of a boundary and generates a detection signal in response thereto. A control circuit, in response to the detection signal, controls the accumulator circuit to block accumulation of the voltages generated by the charge sensing circuit during at least the sensing period in which the detection signal is generated. An analog-to-digital converter circuit then converts an accumulated output voltage from the accumulator circuit to a digital value at the end of an accumulation time period that includes the sensing periods. The end of the accumulation time period is delayed by at least one sensing period in response to the detection signal.
Abstract:
A digital filter receives a sequence of input signal values. A filtering block performs a filtering operation on sequence of input signal values that is controlled by filter coefficients. A control block also receives the sequence of input signal values. The control block evaluates detected changes over time with respect to the sequence of input signal values and selects values for the filter coefficients based on the detected changes. The detected change over time provides an indication of the whether the sequence of input signal values is changing signal state. If so, the filter coefficients are selected to emphasize signal response time over signal noise filtering for the filtering operation. Otherwise, the filter coefficients are selected to emphasize signal noise filtering over signal response time for the filtering operation.
Abstract:
A digital filter receives a sequence of input signal values. A filtering block performs a filtering operation on sequence of input signal values that is controlled by filter coefficients. A control block also receives the sequence of input signal values. The control block evaluates detected changes over time with respect to the sequence of input signal values and selects values for the filter coefficients based on the detected changes. The detected change over time provides an indication of the whether the sequence of input signal values is changing signal state. If so, the filter coefficients are selected to emphasize signal response time over signal noise filtering for the filtering operation. Otherwise, the filter coefficients are selected to emphasize signal noise filtering over signal response time for the filtering operation.
Abstract:
A device includes an analog to digital converter configured to convert voltages into a digital signal by sampling the voltages at a fixed sampling time; a first multiplier configured to multiply the digital signal with in-phase coefficients, the in-phase coefficients generated to produce a demodulated in-phase signal at a demodulation signal frequency; a first adder configured accumulate the demodulated in-phase signal to output in-phase magnitude values; a second multiplier configured to multiply the digital signal with quadrature coefficients, the quadrature coefficients generated to produce a demodulated quadrature signal at the demodulation signal frequency; and a second adder configured to accumulate the demodulated quadrature signal to output quadrature magnitude values.