Pressure-sensitive touch panel
First Claim
1. An apparatus comprising:
- a multiplexer having a plurality of inputs and an output;
a projected capacitance touch panel comprising a layer of piezoelectric material;
a plurality of first electrodes, each first electrode connected to a respective input of the multiplexer;
at least one second electrode, the at least one second electrode separated from the plurality of first electrodes by the layer of piezoelectric material;
a front end module configured to receive a first input signal from the multiplexer output and a second input signal from a signal source, the front end module comprising;
a first stage configured to provide an amplified signal based on the first input signal and the second input signal; and
a second stage comprising a first frequency-dependent filter and a second frequency-dependent filter configured to receive the amplified signal and to provide respective first and second filtered signals,wherein the first filtered signal is based on a potential difference induced between at least one of the plurality of first electrodes and the at least one second electrode in response to a pressure applied to the layer of piezoelectric material and has a first frequency bandwidth, andthe second filtered signal is based on the second input signal and a capacitance in the projected capacitance touch panel and has a second frequency bandwidth which has a relatively higher start-frequency than the first frequency bandwidth.
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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.
245 Citations
17 Claims
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1. An apparatus comprising:
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a multiplexer having a plurality of inputs and an output; a projected capacitance touch panel comprising a layer of piezoelectric material; a plurality of first electrodes, each first electrode connected to a respective input of the multiplexer; at least one second electrode, the at least one second electrode separated from the plurality of first electrodes by the layer of piezoelectric material; a front end module configured to receive a first input signal from the multiplexer output and a second input signal from a signal source, the front end module comprising; a first stage configured to provide an amplified signal based on the first input signal and the second input signal; and a second stage comprising a first frequency-dependent filter and a second frequency-dependent filter configured to receive the amplified signal and to provide respective first and second filtered signals, wherein the first filtered signal is based on a potential difference induced between at least one of the plurality of first electrodes and the at least one second electrode in response to a pressure applied to the layer of piezoelectric material and has a first frequency bandwidth, and the second filtered signal is based on the second input signal and a capacitance in the projected capacitance touch panel and has a second frequency bandwidth which has a relatively higher start-frequency than the first frequency bandwidth. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A method in a projected capacitance touch panel comprising a layer of piezoelectric material, a plurality of first electrodes, and at least one second electrode, the at least one second electrode separated from the plurality of first electrodes by the layer of piezoelectric material, the method comprising:
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selecting each given first electrode of the plurality of first electrodes according to a predetermined sequence, and for each given first electrode; generating an amplified signal based on a first input signal received from the given first electrode and a second input signal received from a signal source; filtering the amplified signal using a first frequency-dependent filter to provide a first filtered signal having a first frequency bandwidth, wherein the first filtered signal is based on a potential difference induced between at least one of the plurality of first electrodes and the at least one second electrode in response to a pressure applied to the layer of piezoelectric material and has a first frequency bandwidth; and filtering the amplified signal using a second frequency dependent filter to provide a second filtered signal, wherein the second filtered signal is based on the second input signal and a capacitance in the projected capacitance touch panel, and has a second frequency bandwidth which has a relatively higher start-frequency than the first frequency bandwidth.
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Specification