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Vehicle seat with capacitive occupant detection system

  • US 8,493,079 B2
  • Filed: 01/21/2009
  • Issued: 07/23/2013
  • Est. Priority Date: 01/31/2008
  • Status: Active Grant
First Claim
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1. An arrangement comprising a vehicle seat in combination with a seat heater and a capacitive occupant detection system, wherein said seat heater comprises a seat heating element disposed in said vehicle seat, wherein said capacitive occupant detection system comprises an electrode arrangement and a measurement circuit;

  • wherein said electrode arrangement is disposed in said vehicle seat and includes a sensing electrode and a shielding electrode, wherein said measurement circuit is operatively connected to said sensing electrode and to said shielding electrode wherein said measurement circuit is configured to keep said sensing electrode and said shielding electrode at substantially the same electric potential during a capacitive measurement, wherein, of said seat heating element, said sensing electrode and said shielding electrode, said seat heating element is closest to a seating region of said vehicle seat, and wherein said sensing electrode is arranged between said seat heating element and said shielding electrode, wherein said seat heater comprises a current source and a current sink, as well as a first node operatively connected between said current source and said seat heating element and a second node operatively connected between said current sink and said seat heating element,wherein said sensing electrode comprises a third node through which said sensing electrode is operatively connected to said capacitive measurement circuit, said shielding electrode comprising a fourth node through which said shielding electrode is operatively connected to said to said capacitive measurement circuit,and wherein an electrically controllable switching arrangement is provided, said switching arrangement comprisingan electrically controllable first switch arranged between said first node and said current source, said first switch having a closed state, in which said first node is connected to said current source by said first switch and an open state, in which said first node is disconnected from said current source by said first switch;

    an electrically controllable second switch arranged between said second node and said current sink, said second switch having a closed state, in which said second node is connected to said current sink by said second switch and an open state, in which said second node is disconnected from said current sink by said second switch;

    an electrically controllable third switch arranged between said first and fourth nodes, said third switch having a closed state, in which said first node is connected to said fourth node by said third switch and an open state, in which said first node is disconnected from said fourth node by said third switch;

    an electrically controllable fourth switch arranged between said second and fourth nodes, said fourth switch having a closed state, in which said second node is connected to said fourth node by said fourth switch and an open state, in which said second node is disconnected from said fourth node by said fourth switch;

    said switching arrangement having a first switching state for heating operation of said seat heater, in which first switching state said first and second switches are in closed state and said third and fourth switches are in open state, and a second switching state for capacitive occupant detection of said capacitive occupant detection system, in which second switching state said first and second switches are in open state and said third and fourth switches are in closed state.

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