Seat heater

• US 9,815,394 B2
• Filed: 08/17/2011
• Issued: 11/14/2017
• Est. Priority Date: 08/20/2010
• 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: Thinnes, Martin
• Primary Examiner(s): Angwin, David
• Assistant Examiner(s): Norton, John J
• Application Number:
  US13/817,867
• Publication Number:
  US 20130147238A1
• Time in Patent Office: 2,281 Days
• Field of Search: 340 39, 340 434
• 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 2/0035 characterised by the sensor data transmission, e.g. wired connections or wireless transmitters therefor; characterised by the sensor data processing, e.g. seat sensor signal amplification or electric circuits for providing seat sensor information
• CPC Class Codes: B60N 2/5685 Resistance
• CPC Class Codes: B60N 2210/12 Capacitive; Electric field
• CPC Class Codes: B60R 21/01532 using electric or capacitive field sensors
• CPC Class Codes: B60R 21/0154 in combination with seat heating

Abstract

A seat heater (10) with a heating element (12) connected between a first (14) and a second (16) nodes comprises a third (18) and a fourth (20) node operatively connectable to a first and a second terminal, respectively, of a power supply. A first electric component (22) providing a controllable first conductance is connected between the first and the third nodes. A second electric component (24) providing a controllable second conductance is connected between the second and the fourth nodes. A control network (26) is connected to the electric components to control the respective conductances and has a mode of operation in which it applies an oscillating signal to the heating element by modulating the first and second conductances in such a way that a voltage drop variation between the third and first nodes is opposite to a voltage drop variation between the second and fourth nodes.

Claims

1. A seat heater in combination with a capacitive sensing device, comprising:

an electric 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, across said heating element;

a first electric component connected between said first node and a third node, said third node being operatively connectable to a first terminal of a power supply, said first electric component providing a controllable first conductance between said first and third nodes;

a second electric component connected between said second node and a fourth node, said fourth node being operatively connectable to a second terminal of said power supply, said second electric component providing a controllable second conductance between said second and fourth nodes;

a control network having a mode of operation in which said control network applies an oscillating signal to said heating element, said control network being connected to said first electric component to control said first conductance and to said second electric component to control said second conductance;

wherein, for applying said oscillating signal to said heating element, said control network is configured to modulate said first conductance and said second conductance in such a way that a variation of a voltage drop between said first and third nodes is of the same amplitude but of opposite sign to a variation of a voltage drop between said fourth and second nodes.

2. The seat heater in combination with the capacitive sensing device as claimed in claim 1, wherein said first electric component comprises a first transistor connected between said first node and said third node, said first transistor having a control node to which said control network is connected to modulate said first conductance;

and wherein said second electric component comprises a second transistor connected between said second node and said fourth node, said second transistor having a control node to which said control network is connected to modulate said second conductance.

3. The seat heater in combination with the capacitive sensing device as claimed in claim 2, wherein said control network comprises an amplifier wherein said first and second transistors form a push-pull output stage.

4. The seat heater in combination with the capacitive sensing device as claimed in claim 2, wherein said control network comprises a voltage source for generating said oscillating signal, said voltage source being operatively connected to the control node of said first transistor;

and wherein said control network comprises a current source including said second transistor.

5. The seat heater in combination with the capacitive sensing device as claimed in claim 4, wherein said current source comprises a reference current source for providing a reference current and a current mirror for drawing across said heating element a current corresponding to said reference current.

6. The seat heater in combination with the capacitive sensing device as claimed in claim 1, wherein said control network has a mode of operation in which said oscillating signal is not applied to said heating element and in which said control network controls said first conductance and said second conductance in such a way as to achieve a target temperature.

7. The seat heater in combination with the capacitive sensing device as claimed in claim 1, wherein said control network comprises an input node for receiving a desired oscillating signal to be applied to said heating element by said control network.

8. The seat heater in combination with the capacitive sensing device as claimed in claim 7, wherein said control network comprises a first feedback branch operatively coupled to said first node to bring an oscillating signal on said first node into accordance with said desired oscillating signal and/or a second feedback branch operatively coupled to said second node to bring an oscillating signal on said second node into accordance with said desired oscillating signal.

9. The seat heater in combination with the capacitive sensing device as claimed in claim 1, wherein said oscillating signal is comprised in a frequency band from 50 kHz to 2 MHz.

10. A capacitive occupancy sensing and heating device, comprising

a seat heater in combination with a capacitive sensing device as claimed in claim 1, said capacitive sensing device being a capacitive occupancy sensor,

wherein said capacitive occupancy sensor includes an antenna electrode and a capacitive sensing network for applying an oscillating signal to said antenna electrode, and

wherein said control network and said capacitive sensing network are configured in such a way that said oscillating signal applied to said antenna electrode and said oscillating signal applied to said heating element are of same amplitude and phase.

11. A vehicle seat comprising a capacitive occupancy sensing and seat heating device as claimed in claim 10, said vehicle seat having a seat surface for accommodating an occupant, wherein said antenna electrode is arranged between said seat surface and said heating element.

12. An automotive vehicle comprising

a first vehicle seat, said first vehicle seat having associated therewith a seat heater in combination with a capacitive sensing device as claimed in claim 1, the heating element of which is arranged in said first vehicle seat, and the oscillating signal of which is indicative of said first vehicle seat;

a second vehicle seat, said second vehicle seat having associated therewith a seat heater in combination with a capacitive sensing device as claimed in claim 1, the heating element of which is arranged in said second vehicle seat, and the oscillating signal of which is indicative of said second vehicle seat;

an appliance including an appliance control device;

wherein said vehicle includes an antenna electrode arranged with said appliance control device and a sensing network associated with said appliance control device, said sensing network being connected to said antenna electrode and configured for detecting an electric signal induced in said antenna electrode in response to an electric field caused by an oscillating signal applied to the heating element arranged in said first vehicle seat or by an oscillating signal applied to the heating element arranged in said second vehicle seat, said electric signal induced in said antenna electrode being indicative of whether an occupant of said first or said second vehicle seat has a part of their body proximate to said appliance control device, and in that said appliance is configured to adapt its behaviour depending on whether an occupant on said first or said second vehicle seat has a part of their body proximate to said appliance control device.

13. The automotive vehicle as claimed in claim 12, wherein said appliance comprises at least one of a radio, a car navigation system, an HVAC system and an infotainment system.

14. A seat heater in combination with a capacitive sensing device, comprising an electric 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, across said heating element;

a first transistor connected between said first node and a third node, said third node being operatively connectable to a first terminal of a power supply, said first transistor providing a controllable first conductance between said first and third nodes;

a second transistor connected between said second node and a fourth node, said fourth node being operatively connectable to a second terminal of said power supply, said second transistor providing a controllable second conductance between said second and fourth nodes;

a control network having a mode of operation in which said control network applies an oscillating signal to said heating element, said control network being connected to said first transistor to control said first conductance and to said second transistor to control said second conductance;

wherein, for applying said oscillating signal to said heating element, said control network is configured to modulate said first conductance and said second conductance in such a way that a variation of a voltage drop between said first and third nodes is of the same amplitude but of opposite sign to a variation of a voltage drop between said fourth and second nodes.

15. The seat heater in combination with the capacitive sensing device as claimed in claim 14, wherein said first transistor comprises a control node, to which said control network is connected to modulate said first conductance;

and wherein said second transistor comprises a control node, to which said control network is connected to modulate said second conductance.