Cambridge Touch Technologies Ltd.

Jackson Chi-Sun Lai

Arokia Nathan

Corbin Church

Suk-Bae Cha

Shuo Gao

An apparatus for combined capacitance and pressure sensing is described. The apparatus includes a multiplexer () having a plurality of inputs () and an output (F), a touch panel (), and a front end module (). The touch panel includes a layer structure (; FIG.) comprising one or more layers, each extending perpendicularly to a thickness direction, the one or more layers including a layer of piezoelectric material (; FIG.), the layer structure having first () and second (; FIG.) opposite faces, and the layer(s) arranged between the first and second faces such that the thickness direction of each layer is perpendicular to the first and second faces. The touch panel also includes a plurality of first electrodes () disposed on the first face, each first electrode connected to a respective input of the multiplexer. The touch panel also includes at least one second electrode () disposed on the second face. The front end module is configured to receive an input signal () from the multiplexer output. The front end module includes a first stage () configured to provide an amplified signal based on the input signal, and a second stage comprising first () and second () frequency-dependent filters configured to receive the amplified signal and to provide respective first () and second () filtered signals. The first filtered signal has a first frequency bandwidth, and the second filtered signal has a second frequency bandwidth which has a relatively higher start-frequency than the first frequency bandwidth.

Pressure-sensitive touch panel

A pressure sensing architecture for use with liquid crystal (LC), organic light emitting diode (OLED), electrophoretic, or other similarly fabricated displays. The described architecture includes a bottom TFT structure and a top structure with color filter material, and with liquid crystal, electrophoretic or OLED material provided in between. A piezoelectric or equivalent material is provided within the display assembly. Transmitting and receiving electrodes can be used to electrically bias the piezoelectric or equivalent material, which provides an analog electrical signal in response to incident touch pressure.

Pressure sensing display device

Switching of power modes for touch screens is disclosed. In example embodiments a touch detect mode may be activated for touchscreen operation. The touchscreen may be a projected capacitance screen that includes force sensing based on piezo electric sensors. The touch detect mode may be a low power mode in which at least one channel, but fewer than all channels of the touch screen are monitored. When is determined that a touch event has occurred a switch to a scan mode for touchscreen operation may be performed. Scan mode may be a higher power mode in which all channels of the touch screen are scanned at least for position sensing. The touch detect mode monitoring may be implemented by monitoring the total charge on the at least one channel and providing a voltage signal. When the voltage signal meets predetermined criteria an indication of a touch event may be generated.

Dynamic switching of power modes for touch screens using force touch

A method is described including receiving (S) a first array of values obtained from measuring an array of touch panel sensor areas (FIG.; I). The method also includes generating (S) a second array of values based on subtracting a reference array of values from the first array of values. The method also includes determining (S) presence of at least one touch event in dependence upon the second array of value and, upon a negative determination (S) generating a new reference array based on exponential smoothing of the reference array and the first array using a weighting factor, wherein the weighting factor is zero, and storing the new reference matrix and, upon a positive determination (S) outputting the second array (FIG.).

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Mississauga, Canada

Jackson Chi-Sun Lai