Seat heater and capacitive occupancy sensor combination
First Claim
1. Combined seat heater and capacitive occupancy sensor, comprisinga heater network including a heating element connected between a first node and a second node to dissipate heat when a heating current is caused to flow between said first and second nodes,a capacitive sensing network connected to said heating element configured to apply an oscillating current thereto and to derive a complex impedance of said heating element from a voltage resulting on said heating element in response to said application of said oscillating current;
- wherein said heater network comprises a common mode choke connecting said first and said second node to a third and a fourth node, respectively, and wherein said capacitive sensing network comprisesmeans to sustain said oscillating current in or to drive said oscillating current into said heating element;
as well as a high-impedance amplifier having an input node operatively connected to said heating element, to probe said voltage, and an output node to provide an output signal indicative of said voltage, said high-impedance amplifier having a complex impedance with a reactive part and a resistive part, the reactive part of the complex impedance of the high-impedance amplifier being at least five times higher than a reactive part of the complex impedance of said heating element and the resistive part of the complex impedance of the high-impedance amplifier being at least five times higher than a resistive part of the complex impedance of said heating element.
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Accused Products
Abstract
A combined seat heater and capacitive occupancy sensor comprises a heater network and a capacitive sensing network. The heater network includes a heating element (10) connected between a first node (21) and a second node (22) to dissipate heat. The capacitive sensing network is connected to the heating element to apply an oscillating current thereto and to derive a capacitive load of the heating element from the voltage resulting on the heating element. The heater network comprises a common mode choke (16) connecting the first and the second node to a third (23) and a fourth (24) node, respectively. The capacitive sensing network further comprises means to sustain the oscillating current in or to drive the oscillating current into the heating element as well as a high-impedance amplifier (32) having an input node operatively connected to the heating element to probe the resulting voltage, and an output node (44) to provide an output signal indicative of the voltage.
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Citations
17 Claims
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1. Combined seat heater and capacitive occupancy sensor, comprising
a heater network including a heating element connected between a first node and a second node to dissipate heat when a heating current is caused to flow between said first and second nodes, a capacitive sensing network connected to said heating element configured to apply an oscillating current thereto and to derive a complex impedance of said heating element from a voltage resulting on said heating element in response to said application of said oscillating current; -
wherein said heater network comprises a common mode choke connecting said first and said second node to a third and a fourth node, respectively, and wherein said capacitive sensing network comprises means to sustain said oscillating current in or to drive said oscillating current into said heating element; as well as a high-impedance amplifier having an input node operatively connected to said heating element, to probe said voltage, and an output node to provide an output signal indicative of said voltage, said high-impedance amplifier having a complex impedance with a reactive part and a resistive part, the reactive part of the complex impedance of the high-impedance amplifier being at least five times higher than a reactive part of the complex impedance of said heating element and the resistive part of the complex impedance of the high-impedance amplifier being at least five times higher than a resistive part of the complex impedance of said heating element. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. Combined seat heater and capacitive occupancy sensor, comprising a heater network including a heating element connected between a first node and a second node to dissipate heat when a heating current is caused to flow between said first and second nodes,
a capacitive sensing network connected to said heating element configured to apply an oscillating current thereto and to derive a complex impedance of said heating element in response to said application of said oscillating current, wherein said heater network comprises a common mode choke connecting said first and said second node to a third and a fourth node, respectively, wherein said common mode choke comprises inductively coupled windings having a coupling factor of more than 99%; - and,
wherein said capacitive sensing network comprises means to sustain said oscillating current in or to drive said oscillating current into said heating element and a high-impedance amplifier having an input node operatively connected to said heating element, to probe said voltage, and an output node to provide an output signal indicative of said voltage, said high-impedance amplifier having a complex impedance with a reactive part and a resistive part, the reactive part of the complex impedance of the higher-impedance amplifier being at least five times higher than a reactive part of the complex impedance of said heating element and the resistive part of the complex impedance of the high-impedance amplifier being at least five times higher than a resistive part of the complex impedance of said heating element.
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17. Combined seat heater and capacitive occupancy sensor, comprising
a heater network including a heating element connected between a first node and a second node to dissipate heat when a heating current is caused to flow between said first and second nodes, a capacitive sensing network connected to said heating element configured to apply a oscillating current thereto and to derive a complex impedance of said heating element from a voltage resulting on said heating element in response to said application of said oscillating current, wherein said heater network comprises a common mode choke connecting said first and said second node to a third and fourth node, respectively, and wherein said common mode choke comprises inductively coupled windings formed by wires wound in bifilar way; - and
wherein said capacitive sensing network comprises means to sustain said oscillating current in or to drive said oscillating current into said heating element; said a high-impedance amplifier having an input node operatively connected to said heating element, to probe said voltage, and an output node to provide an output signal indicative of said voltage, said high-impedance amplifier having a complex impedance with a reactive part and a resistive part, the reactive part of the complex impedance of the high-impedance amplifier being at least five times higher than a reactive part of the complex impedance of said heating element and the resistive part of the complex impedance of the high-impedance amplifier being at least five times higher than a resistive part of the complex impedance of said heating element.
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Specification