SEAT HEATER USABLE AS ANTENNA ELECTRODE

• US 20130270874A1
• Filed: 12/07/2011
• Published: 10/17/2013
• Est. Priority Date: 12/17/2010
• Status: Active Grant

• Current Assignee: IEE International Electronics & Engineering SA (Aerospace Hi-Tech Holding Group Company Limited)
• Original Assignee: IEE International Electronics & Engineering SA (Aerospace Hi-Tech Holding Group Company Limited)
• Inventors: Lamesch, Laurent
• Granted Patent: US 9,764,669 B2
• Time in Patent Office: Days
• US Class Current: 297/180.12
• CPC Class Codes: B60N 2/002 Seats provided with an occupancy detection means mounted therein or thereon detection means responsive to presence or absence of children B60N2/266
• CPC Class Codes: B60N 2/5685 Resistance
• CPC Class Codes: B60R 21/01532 using electric or capacitive field sensors

Abstract

A seat heater, e.g. for a vehicle seat, comprises a heating element (10) for dissipating heat when a heating current flows across it and a temperature sensor (15) for providing a temperature signal indicative of the seat temperature. The seat heater comprises a common mode choke (16) with at least three windings. The heating element is connected in series between a first (16.1) and a second (16.2) thereof so as to be operatively connectable to a power source (12) via the common mode choke. The temperature sensor is connected to a third winding (16.3) of the at least three windings in such a way that the temperature signal may be received, e.g. by a temperature controller of the seat heater, via the third winding of the common mode choke.

Claims

1. A seat heater, comprising

a heating element for dissipating heat when a heating current is caused to flow across said heating element;

a temperature sensor for providing a temperature signal;

wherein

said seat heater comprises a common mode choke with at least three windings,

said heating element being connected in series between a first and a second winding of said at least three windings so as to be operatively connectable to a power source via said common mode choke;

said temperature sensor being connected to a third winding of said at least three windings in such a way that said temperature signal may be received via said common mode choke.

2. The seat heater as claimed in claim 1, wherein said temperature sensor comprises a first and a second terminal, said temperature sensor being connected to said third winding with said first terminal and to said heating element with its second terminal.

3. The seat heater as claimed in claim 1, wherein said temperature sensor comprises a first and a second terminal, wherein said at least three windings include a fourth winding, said temperature sensor being connected to said third winding with said first terminal and to said fourth winding with its second terminal.

4. The seat heater as claimed in claim 1, comprising a temperature controller operatively connected to said temperature sensor via said third winding for receiving said temperature signal and to said heating element via said first or said second winding for regulating said heating current depending on said temperature signal received.

5. The seat heater as claimed in claim 1, comprising a support element having said heating element and said temperature sensor arranged thereon.

16. The seat heater as claimed in claim 5, wherein said support element comprises an electrically insulating film.

6. An assembly of a capacitive seat occupancy sensor and a seat heater, said seat heater, comprising

a heating element for dissipating heat when a heating current is caused to flow across said heating element;

a temperature sensor for providing a temperature signal;

wherein said seat heater comprises a common mode choke with at least three windings;

said heating element being connected in series between a first and a second winding of said at least three windings so as to be operatively connectable to a power source via said common mode choke;

said temperature sensor being connected to a third winding of said at least three windings in such a way that said temperature signal may be received via said common mode choke.

7. The assembly as claimed in claim 6, wherein said capacitive seat occupancy sensor comprises a capacitive sensing network operatively 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.

8. The assembly as claimed in claim 7, wherein said capacitive sensing network comprises a means to sustain an oscillating signal in or to drive an oscillating signal into said heating element and a high-impedance amplifier having an input node operatively connected to said heating element to probe said oscillating signal and an output node to provide an output signal indicative of said oscillating signal.

9. The assembly as claimed in claim 8, wherein said capacitive sensing network comprises a reference component having a known complex impedance and a switch to operatively connect said reference component between said heating element and ground.

10. The assembly as claimed in claim 8, wherein said heating element has a capacitance to ground, said common mode choke forming a parallel resonant network with said capacitance.

11. The assembly as claimed in claim 10, wherein said means to sustain an oscillating signal in or to drive an oscillating signal into said heating element comprises

a negative resistance device to sustain an oscillating signal in said resonant network and to compensate for resistive losses and power extracted from said resonant network, and/or

an AC source operatively connected to said heating element to drive an alternative current into said resonant network and a frequency control unit for controlling the frequency of said alternative current.

12. The assembly as claimed in claim 7,

wherein said heating element includes a first node with which said heating element is connected to said first winding, said first winding connecting said first node to a third node,

wherein said heating element includes a second node with which said heating element is connected to said second winding, said second winding connecting said second node to a fourth node,

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.

17. The assembly as claimed in claim 9, wherein said reference component comprises a reference capacitor.

13. Vehicle seat, comprising

at least one of a seat heater and an assembly of a capacitive seat occupancy sensor and a seat heater, said seat heater comprising

a heating element for dissipating heat when a heating current is caused to flow across said heating element;

a temperature sensor for providing a temperature signal;

wherein said seat heater comprises a common mode choke with at least three windings;

said heating element being connected in series between a first and a second winding of said at least three windings so as to be operatively connectable to a power source via said common mode choke;

said temperature sensor being connected to a third winding of said at least three windings in such a way that said temperature signal may be received via said common mode choke.

14. A vehicle seat as claimed in claim 13, comprising an assembly of a capacitive seat occupancy sensor and a seat heater, wherein assembly comprises a driven shield electrode.

15. A capacitive sensing network configured to apply an oscillating voltage to an antenna electrode and to derive a capacitive load of said antenna electrode from a current flowing into said antenna electrode in response to said application of said oscillating voltage, said capacitive sensing network comprising an interface for connecting said capacitive sensing network to a seat heater including a heating element for dissipating heat when a heating current is caused to flow across said heating element and a temperature sensor for providing a temperature signal, said interface being configured for operating said heating element as said antenna electrode, said capacitive sensing network being characterized in that said interface comprises a common mode choke including a first winding for connecting a first node of said heating element to a first terminal of a power supply, a second winding for connecting a second node of said heating element to a second terminal of said power supply and a third winding for connecting said temperature sensor to a temperature controller.