Method of capacitive measurement between an object and an electrode plane by partial synchronous demodulation
First Claim
1. A method of capacitive measurement between an object and an electrode plane, in which method a processor unit operates as follows:
- applying an excitation signal to the electrode plane;
generating a control signal for a mixing circuit, the control signal defining a measurement window and a time-lapse window for the mixing circuit; and
determining a capacitance value representative of a capacitance between the object and an electrode in the electrode plane based on a measurement from a measurement signal originating from the electrode plane,wherein the excitation signal is a non-sinusoidal signal comprising at least one discontinuity, and in order to determine the capacitance value, the measurement signal is evaluated during the measurement window and not evaluated during the time-lapse window, the time-lapse window being a time period during which said at least one discontinuity is occurring, and the measurement window being a time period free of said at least one discontinuity.
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Accused Products
Abstract
A method of capacitive measurement between an object and an electrode plane includes applying an excitation signal to the resistive electrode plane, and determining a value of capacitance on the basis of a measurement of a measurement signal originating from the electrode plane. The excitation signal is a nonsinusoidal signal having at least one discontinuity. To determine the value of capacitance, the measurement signal is attenuated over a time window, this time window being the duration for which the resistivity of the electrode plane is manifested on the measurement signal in response to the at least one discontinuity.
49 Citations
17 Claims
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1. A method of capacitive measurement between an object and an electrode plane, in which method a processor unit operates as follows:
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applying an excitation signal to the electrode plane; generating a control signal for a mixing circuit, the control signal defining a measurement window and a time-lapse window for the mixing circuit; and determining a capacitance value representative of a capacitance between the object and an electrode in the electrode plane based on a measurement from a measurement signal originating from the electrode plane, wherein the excitation signal is a non-sinusoidal signal comprising at least one discontinuity, and in order to determine the capacitance value, the measurement signal is evaluated during the measurement window and not evaluated during the time-lapse window, the time-lapse window being a time period during which said at least one discontinuity is occurring, and the measurement window being a time period free of said at least one discontinuity. - View Dependent Claims (2, 3, 4, 5)
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6. An electronic device comprising:
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a display screen associated with a capacitive detection device, the capacitive detection device comprising an electrode plane; and a processor unit electrically couplable to the electrode plane for detecting the position of an object with respect to the display screen by measuring the capacitance between said object and the electrode plane, the processor unit capable of applying an excitation signal to the electrode plane, the excitation signal being a non sinusoidal signal comprising at least one discontinuity, generating a control signal for a mixing circuit, the control signal defining a measurement window and a time-lapse window for the mixing circuit, and determining a capacitance value representative of a capacitance between the object and an electrode in the electrode plane based on a measurement from a measurement signal originating from the electrode plane, the measurement signal evaluated during the measurement window and not evaluated within the time-lapse window, this time-lapse window being a time period during which said at least one discontinuity is occurring, and the measurement window being a time period free of said at least one discontinuity. - View Dependent Claims (7, 8, 9, 10)
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11. An electronic device, comprising:
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a processor unit for detecting a position of an object with respect to a capacitive detection device including an electrode plane by measuring a capacitance between the object and one or more electrodes in the electrode plane, the processor unit electrically couplable to the electrode plane and capable of applying an excitation signal to the electrode plane;
the excitation signal being a non sinusoidal signal comprising at least one discontinuity, the processor unit further capable of generating a control signal for a mixing circuit, the control signal defining a measurement window and a time-lapse window for the mixing circuit; andan electronic circuit electrically coupled to the processor unit and including the mixing circuit, the electronic circuit electrically couplable to the electrode plane and configured for receiving a measurement signal from the one or more electrodes, evaluating the measurement signal during the measurement window and not evaluating the measurement signal during the time-lapse window, the time-lapse window being a time period during which the at least one discontinuity is occurring, and the measurement window being a time period free of the at least one discontinuity; wherein the processor unit is further capable of determining a capacitance value representative of a capacitance between the object and an electrode in the electrode plane based on the evaluated measurement signal. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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Specification