Methods and apparatus for capacitive sensing
First Claim
1. A sensing device, comprising:
- a conductive sensing member having a sensing surface and an opposite surface, wherein the sensing surface comprises an outer surface of an electronic device housing, wherein the sensing member is at a floating potential;
a conductive reference member in spaced relation to the opposite surface of the sensing member, wherein the conductive reference member forms a capacitor with the conductive sensing member; and
a capacitance sensing device coupled to both the conductive reference member and to ground, wherein the capacitance sensing device is configured to determine a change in capacitance between the conductive reference member and ground resulting from proximity of a human.
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Abstract
The present disclosure addresses methods and apparatus facilitating capacitive sensing using a conductive surface, and facilitating the sensing of proximity to the conductive surface. The sensed proximity will often be that of a user, but can be another source of a reference voltage potential. In some examples, the described systems are capable of sensing capacitance (including parasitic capacitance) in a circuit that includes the outer conductive surface, and where that outer conductive surface is at a floating electrical potential. In some systems, the systems can be switched between two operating modes, a first mode in which the system will sense proximity to the conductive surface, and a second mode in which the system will use a capacitance measurement to sense contact with the conductive surface.
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Citations
28 Claims
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1. A sensing device, comprising:
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a conductive sensing member having a sensing surface and an opposite surface, wherein the sensing surface comprises an outer surface of an electronic device housing, wherein the sensing member is at a floating potential; a conductive reference member in spaced relation to the opposite surface of the sensing member, wherein the conductive reference member forms a capacitor with the conductive sensing member; and a capacitance sensing device coupled to both the conductive reference member and to ground, wherein the capacitance sensing device is configured to determine a change in capacitance between the conductive reference member and ground resulting from proximity of a human. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of determining the proximity of a user to an electronic device having a metal surface component, comprising:
measuring a total capacitance between a reference electrode and a ground, wherein the total capacitance comprises a first capacitance between the metal surface component and the reference electrode and a second capacitance between the metal surface component and a reference, wherein the second capacitance is responsive to proximity of an external source of electric potential, and wherein the metal surface component comprises an outer surface of an electronic device housing. - View Dependent Claims (9, 10, 11)
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12. A method of operating an electronic device, comprising the acts of:
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determining a first capacitance between a metal surface component and a reference electrode, the reference electrode tied to a sensing device and placed proximate the metal surface component, with the metal surface component at a floating potential; identifying a second capacitance between the floating potential metal surface component and a reference, the second capacitance responsive to the presence of an external source of electric potential; identifying the proximity of a user to the metal surface component in response to a parameter of a capacitance measurement comprising a change in the second capacitance; in response to an identified proximity of a user, coupling the metal surface component to a direct current voltage reference; and identifying a contact with the metal surface component causing deflection of a portion of the metal surface component by measuring a change in capacitance between the metal surface component and the reference electrode resulting from the deflection, wherein the metal surface component comprises a location that in a first state forms an invisible contact location and in a second state forms a visible contact location, and wherein the method further comprises transitioning the location from the first state to the second state in response to the identified proximity of a user. - View Dependent Claims (13, 14, 15, 16, 17)
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18. An electronic assembly, comprising:
a capacitance sensing assembly that is operable in two states, a first state in which the assembly detects proximity of a source of electric potential and a second state in which the assembly detects contact with a source of electric potential, the sensing assembly comprising, a metal sensing member having a sensing surface and an opposite surface, and a first capacitive reference member in spaced relation to the opposite surface of the metal sensing member, and forming a capacitor with the metal sensing member, a switching assembly to selectively connect the metal sensing member between a first state in which the metal sensing member is at a floating potential and a second state in which the metal sensing member is coupled to a reference voltage, and a capacitance sensing device coupled to both the first capacitive reference member and the reference voltage, the capacitance sensing assembly configured to, determine a first parameter of change in capacitance between the conductive reference member and ground resulting from proximity of a source of electric potential relative to the metal sensing member when the metal sensing member is in the first floating state, generate a sensed proximity signal in response to the determined first parameter; and determine a second parameter of change in capacitance between the conductive reference member and the metal sensing resulting from contact of a source of electric potential with the metal sensing member causing deflection of the metal sensing member when the metal sensing member is in the second state, and generate a touch input signal in response to be determined second parameter. - View Dependent Claims (19, 20, 21, 22)
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23. A laptop computer moveable between a closed lid state and an open lid state, comprising:
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at least one processor; a capacitance sensing mechanism proximate a selected region of an external surface of the computer when the computer is in the closed lid state; and machine readable storage media containing instructions comprising, instructions to enable the capacitance sensor to detect a change in capacitance proximate the selected region of the external surface of the computer, when the computer is in the closed lid state, instructions to receive the detected capacitance as a touch input; and instructions to execute a touch responsive functionality in response to the sensed touch input. - View Dependent Claims (24, 25, 26, 27, 28)
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Specification