Stmicroelectronics Asia Pacific Pte Limited

Ade Putra

Kusuma Adi Ningrat

Mythreyi Nagarajan

Manivannan Ponnarasu

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.

Methods and apparatus for demodulating digital signals

In one embodiment, a method for operating an electronic device includes determining that a touch sensitive display is being contacted. The touch sensitive display includes a plurality of mutual-sensing capacitive sensor regions and an array of self-sensing capacitive sensor regions. The plurality of mutual-sensing capacitive sensor regions is arranged in rows and columns on the touch sensitive display. The array of self-sensing capacitive sensor regions is arranged in a row or a column on the touch sensitive display. The method may include obtaining mutual sensing touch values for each of the rows and the columns and self-sensing touch values for the row or the column. Based on the mutual sensing touch values and self-sensing touch values, the method includes determining whether a contacted region of the touch sensitive display is an impression of a single finger, multiple fingers, a single thumb, or multiple thumbs.

Electronic device with finger touch detection and related methods

A touch screen controller includes driving circuitry coupled to a conductive line through a resistance and drives that conductive line with a driving signal passed through the resistance at a drive frequency. Sensing circuitry is coupled to that conductive line and senses a voltage at that conductive line, the voltage being a function of a capacitance seen by that conductive line. Analog to digital conversion circuitry is coupled to the sensing circuitry and samples the sensed voltage at a sampling frequency to produce samples. Processing circuitry is coupled to the analog to digital conversion circuitry and directly calculates a tangent of a phase shift of the voltage due to the resistance and the capacitance from the samples, and determines a self touch value for that conductive line as a function of the tangent of the phase shift of the voltage.

Self capacitance sensing based on tangent of phase shift of drive signal

A touch screen controller includes drive circuitry driving force lines with a force signal in a touch data sensing mode and not driving the force lines in a noise sensing mode, sense circuitry sensing touch data at the sense lines in the touch data sensing mode and sensing noise data at the sense lines during the noise sensing mode. Processing circuitry: a) samples the noise data, b) performs trigonometric manipulations of the noise data to produce imaginary noise data and real noise data, and c) determines a noise magnitude value of the noise data as a function of the imaginary noise data and the real noise data. In the noise sensing mode, (a)-(c) are performed for each of a plurality of possible sampling frequencies to be used in the touch data sensing mode in order to determine which sampling frequency is to be used in the touch data sensing mode.

Mutual capacitance sensing using magnitude noise sensing with trigonometric multipliers

Disclosed herein is a touch screen controller operable with a touch screen having force lines and sense lines. The touch screen controller includes drive circuitry driving the force lines with a force signal in a touch data sensing mode and not driving the force lines in a noise sensing mode. Sense circuitry senses data at the sense lines in the touch data sensing mode and the noise sensing mode. Processing circuitry samples the data, multiplies the data by a sine multiplier to produce imaginary data, sums the imaginary data, multiplies the data by a cosine multiplier to produce real data, sums the real data, and determines magnitude values of the data as a function of the imaginary data and the real data.

Mutual capacitance sensing using magnitude noise sensing with sine and cosine multipliers

A method for touch screen self-capacitance foreign matter detection for a capacitive touch screen is disclosed. By iteratively performing methods of self-capacitance scanning and foreign matter scanning foreign matter may be detected.

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Singapore, Singapore

Ade Putra