Cambridge Touch Technologies Ltd.

Riccardo Micci

Arokia Nathan

Paul Richard Routley

Babak Bastani

Michael Robert Astley

Xiang Cheng

Jiahao Li

Matteo Vit

Constantinos Tsangarides

Paridhi Sharma

A method of processing a number of force values is described. Each force value corresponds to a sensor location. The sensor locations are spaced apart along a direction. The method includes receiving the force values (S). The method also includes determining whether the force values include one or more candidate peaks (S). Each candidate peak corresponds to a local maximum of the force values. The method also includes, in response to at least one candidate peak exceeds a minimum force threshold (S), interpolating the force values and estimating a number of peak coordinates and corresponding peak force values based on the interpolated force values and the candidate peaks (S) which exceed the minimum force threshold.

Force signal processing

An apparatus () is described which includes a touch panel (). The touch panel () includes a layer of piezoelectric material () disposed between a number of sensing electrodes () and at least one counter electrode (). The apparatus () also includes a touch controller () connected to the touch panel (). The touch controller () is configured to determine, in response to receiving piezoelectric signals () from one or more of the sensing electrodes (), a location () and an applied force () corresponding to a user interaction () with the touch panel (). The touch controller () is configured to determine a capacitance value () of one or more of the sensing electrodes (). The touch controller is configured to operate in a force-based mode, a capacitance-based mode or a mixed force-capacitance mode depending on the type of input received.

Force sensing touch panel

An apparatus () for processing signals from a touch panel () is described. The touch panel () includes a layer of piezoelectric material () disposed between a number of sensing electrodes () and at least one common electrode (). The apparatus () includes a capacitive touch controller () for connection to the sensing electrodes (). The apparatus () also includes a switch network () including a number of inputs for connection to some or all of the sensing electrodes (), and an output connected to system ground or a common mode voltage (V). The apparatus () also includes a second circuit () for connection to the at least one common electrode () and configured to generate, based on signals received from the at least one common electrode, a second pressure signal () indicative of a total pressure applied to the touch panel (). The apparatus () also includes a controller () configured to control the switch network () to couple any connected sensing electrodes () to system ground or the common mode voltage (V) during a pressure measurement period, and to determine an estimate of the total pressure based on the second pressure signal during the pressure measurement period.

Pressure sensing apparatus and method

An apparatus for processing signals from a touch panel. The touch panel includes a layer of piezoelectric material disposed between a number of sensing electrodes and one or more common electrodes. The apparatus includes a capacitive touch controller for connection to the sensing electrodes and a switch network including inputs for connection to the sensing electrodes and an output connected to system ground or a common mode voltage. The apparatus includes a circuit for connection to the common electrodes and to generate, for each common electrode, a corresponding pressure signal indicative of a pressure applied to the touch panel proximate to that common electrode. The apparatus includes a controller to control the switch network to couple any connected sensing electrodes to system ground or the common mode voltage during a pressure measurement period, and to sample the one or more second pressure signals during the pressure measurement period.

Touch panel system with piezoelectric pressure sensing

A method includes receiving (S), from a touch panel (), force values () corresponding to a plurality of piezoelectric sensors (), Each piezoelectric sensor corresponds to a physical location (xm, yn) on the touch panel. The method also includes receiving (S) one or more user touch locations corresponding to user touches, The method also includes excluding (S) all force values () corresponding to physical locations within a distance of a user touch location, and setting the remaining force values () as valid force values (S). The method also includes interpolating and/or extrapolating (S), based on the valid force values, one or more reconstructed force values () corresponding to same physical locations (xm, yn) as the respective excluded force values ().

Pressure signal processing

An apparatus () for processing signals from a touch panel () is described. The touch panel () includes a layer of piezoelectric material () disposed between a plurality of sensing electrodes () and at least one common electrode (). The apparatus () includes a first circuit () for connection to the plurality of sensing electrodes (). The first circuit () is configured to generate a plurality of first pressure signals (). Each first pressure signal () corresponds to one or more sensing electrodes () and is indicative of a pressure acting on the touch panel () proximate to the corresponding one or more sensing electrodes (). The apparatus also includes a second circuit () for connection to the at least one common electrode (). The second circuit () is configured to generate a second pressure signal () indicative of a total pressure applied to the touch panel (). The apparatus also includes a controller () configured to determine an estimate of the total pressure based on a weighted difference of the second pressure signal () and a sum over the plurality of first pressure signals ().

Mitigation of external fields in piezoelectric sensors

An apparatus () for processing signals from a touch panel () is described. The touch panel () includes a layer of piezoelectric material () disposed between a plurality of sensing electrodes () and at least one common electrode (). The apparatus () includes a first circuit () for connection to the plurality of sensing electrodes (). The first circuit () is configured to generate one or more first pressure signals (). Each first pressure signal () corresponds to one or more sensing electrodes () and is indicative of a pressure acting on the touch panel () proximate to the corresponding one or more sensing electrodes (). The apparatus also includes a second circuit () for connection to the at least one common electrode (). The second circuit () is configured to generate a second pressure signal () indicative of a total pressure applied to the touch panel (). The apparatus also includes a controller () configured to determine an estimate of the total pressure based on a weighted difference of the second pressure signal () and a sum over the one or more first pressure signals ().

A method includes receiving (S), from a touch panel (), force values () corresponding to a plurality of piezoelectric sensors (). Each piezoelectric sensor corresponds to a physical location (x, y) on the touch panel. The method also includes receiving (S) an identification of which, if any, of the force values () are influenced by coupling to external electric fields. The method also includes, in response to one or more force values () being identified as influenced by coupling to external electric fields (S), setting the corresponding force values () as excluded force values (S), and setting the remaining force values () as valid force values (S). The method also includes interpolating and/or extrapolating (S), based on the valid force values, one or more reconstructed force values () corresponding to same physical locations (x, y) as the respective excluded force values ().

Apparatus () for processing signals from a touch panel () is described. The touch panel () includes a layer of piezoelectric material () disposed between a plurality of sensing electrodes () and at least one common electrode (). The apparatus () includes a first circuit () for connection to the plurality of sensing electrodes (). The first circuit () is configured to generate a plurality of first pressure signals (). Each first pressure signal () corresponds to one or more sensing electrodes () and is indicative of a pressure acting on the touch panel () proximate to the corresponding one or more sensing electrodes (). The apparatus () also includes a second circuit () for connection to the at least one common electrode (). The second circuit () is configured to generate a second pressure signal () indicative of a total pressure applied to the touch panel (). The apparatus () also includes a controller () configured to determine an external interference signal () based on a weighted sum over the second pressure signal () and the plurality of first pressure signals (). The controller () is also configured to compare the external interference signal () against a pre-calibrated threshold (V). The controller is also configured, in response to the external interference signal () being greater than or equal to the pre-calibrated threshold (V), to output an interference flag (Int) indicating that the first and second pressure signals () are influenced by coupling to one or more external electrical fields.

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Cambridge, United Kingdom

Riccardo Micci