COMBINED SEAT HEATER AND CAPACITIVE OCCUPANCY SENSOR
1 Assignment
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Accused Products
Abstract
A combined seat heater and capacitive occupancy sensor comprises a heating element (10) connected between a first (21) and a second (22) node, and a capacitive sensing network connected to the heating element to apply an oscillating voltage thereto and to derive the capacitive load of the heating element. A common mode choke (16) connects the first and second node to a third (23) and fourth (24) node, respectively. The capacitive sensing network comprises an oscillator (28), AC-coupled to the third and/or the fourth node to drive oscillating voltage into that node, and a transimpedance amplifier (32), which has a first input to receive the oscillating voltage as reference voltage and a second input operatively connected to the heating element. The transimpedance amplifier maintains a voltage on its second input equal to the reference voltage by driving a current into the second input. An output signal (44) indicates the AC component of the current driven into the second input.
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Citations
37 Claims
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1-18. -18. (canceled)
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19. 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 to apply an oscillating signal thereto and to derive a capacitive load of said heating element from a current flowing into or a voltage resulting on said heating element in response to said application of said oscillating signal; wherein said heater network comprises a common mode choke connecting said first and said second node to a third and a fourth node, respectively. - View Dependent Claims (20, 21, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
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22. 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 to apply an oscillating voltage thereto and to derive a capacitive load of said heating element from a current flowing into said heating element in response to said application of said oscillating voltage; -
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 an oscillator which is AC-coupled to at least one of said third and fourth nodes to drive said oscillating voltage into said at least one of said third and fourth nodes; as well as a transimpedance amplifier having a first input AC-coupled to said at least one of said third and fourth nodes to receive said oscillating voltage as an AC component of a reference voltage, a second input operatively connected to at least one of said first and second nodes, said transimpedance amplifier being configured to maintain a voltage on said second input node equal to said reference voltage by driving a current into said second input, said transimpedance amplifier having an output to provide a signal indicative at least of an AC component of said current driven into said second input. - View Dependent Claims (23, 24, 25, 26)
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Specification