Pressure-sensitive touch panel
First Claim
1. A device for processing signals from a projected capacitance touch panel, the panel comprising a layer of piezoelectric material disposed between a plurality of first electrodes and at least one second electrode, the device configured, in response to receiving input signals from a given first electrode, to generate a pressure signal indicative of a pressure applied to the touch panel proximate to the given first electrode and a capacitance signal indicative of a capacitance of the given first electrode based on the input signals,wherein the pressure signal is based on a potential difference induced between the first electrodes and the at least one second electrode in response to the pressure applied to a portion of the layer of piezoelectric material proximate to the given first electrode, and has a first frequency bandwidth, and the capacitance signal is based on a capacitance measurement signal and the capacitance of the given first electrode, and has a second frequency bandwidth which has a relatively higher start-frequency than the first frequency bandwidth,and wherein the device comprises at least one signal splitter configured to split the input signals received from the touch panel into first and second input signals, to pass the first input signals to a first frequency dependent filter configured to reject the pressure signal and pass the capacitance signal, and to pass the second input signals to a second frequency dependent filter configured to reject the capacitance signal and pass the pressure signal.
1 Assignment
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Accused Products
Abstract
An apparatus for combined capacitance and pressure sensing is described. The apparatus includes a multiplexer (75) having a plurality of inputs (76) and an output (F), a touch panel (29), and a front end module (3). The touch panel includes a layer structure (5; FIG. 15) comprising one or more layers, each extending perpendicularly to a thickness direction, the one or more layers including a layer of piezoelectric material (10; FIG. 15), the layer structure having first (6) and second (7; FIG. 15) 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 (8) 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 (9) disposed on the second face. The front end module is configured to receive an input signal (11) from the multiplexer output. The front end module includes a first stage (12) configured to provide an amplified signal based on the input signal, and a second stage comprising first (13) and second (14) frequency-dependent filters configured to receive the amplified signal and to provide respective first (16) and second (17) 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.
243 Citations
15 Claims
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1. A device for processing signals from a projected capacitance touch panel, the panel comprising a layer of piezoelectric material disposed between a plurality of first electrodes and at least one second electrode, the device configured, in response to receiving input signals from a given first electrode, to generate a pressure signal indicative of a pressure applied to the touch panel proximate to the given first electrode and a capacitance signal indicative of a capacitance of the given first electrode based on the input signals,
wherein the pressure signal is based on a potential difference induced between the first electrodes and the at least one second electrode in response to the pressure applied to a portion of the layer of piezoelectric material proximate to the given first electrode, and has a first frequency bandwidth, and the capacitance signal is based on a capacitance measurement signal and the capacitance of the given first electrode, and has a second frequency bandwidth which has a relatively higher start-frequency than the first frequency bandwidth, and wherein the device comprises at least one signal splitter configured to split the input signals received from the touch panel into first and second input signals, to pass the first input signals to a first frequency dependent filter configured to reject the pressure signal and pass the capacitance signal, and to pass the second input signals to a second frequency dependent filter configured to reject the capacitance signal and pass the pressure signal.
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12. A method of processing signals from a projected capacitance touch panel, the panel comprising a layer of piezoelectric material disposed between a plurality of first electrodes and at least one second electrode, the method comprising:
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receiving input signals from a given first electrode; splitting the received input signals into first and second input signals using a signal splitter to pass the first input signals to a first frequency dependent filter and the second input signals to a second frequency dependent filter; generating a pressure signal indicative of a pressure applied to the touch panel proximate to the given first electrode by filtering the second input signals using the second frequency dependent filter to reject the capacitance signal and pass the pressure signal, wherein the pressure signal is based on a potential difference induced between the given first electrode and the at least one second electrode in response to the pressure applied to a portion of the layer of piezoelectric material proximate to the given first electrode and has a first frequency bandwidth; and generating a capacitance signal indicative of a capacitance of the given first electrode by filtering the first input signals using the first frequency dependent filter to reject the pressure signal and pass the capacitance signal, wherein the capacitance signal is based on a capacitance measurement signal and a capacitance of the given first electrode, and has a second frequency bandwidth which has a relatively higher start-frequency than the first frequency bandwidth. - View Dependent Claims (13, 14, 15)
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Specification