Capacitive proximity sensor

• US 6,724,324 B1
• Filed: 08/21/2000
• Issued: 04/20/2004
• Est. Priority Date: 08/21/2000
• Status: Expired due to Fees

• Current Assignee: Strattec Power Access LLC (Strattec Security Corporation)
• Original Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Inventors: Lambert, David Kay
• Primary Examiner(s): EDWARDS JR, TIMOTHY
• Application Number:
  US09/643,236
• Time in Patent Office: 1,338 Days
• Field of Search: 341/33, 324/658, 324/688, 324/663, 324/662, 340/870.37, 340/562, 340/561, 345/174
• US Class Current: 341/33
• CPC Class Codes: E05F 15/46 responsive to changes in electrical capacitance
• CPC Class Codes: E05Y 2900/50 for vehicles
• CPC Class Codes: H03K 17/955 using a capacitive detector
• CPC Class Codes: H03K 2217/960765 Details of shielding arrangements
• CPC Class Codes: H03K 2217/960775 Emitter-receiver or "fringe" type detection, i.e. one or more field emitting electrodes and corresponding one or more receiving electrodes

Abstract

A capacitive sensor including a first electrode that has at least one conducting surface being disposed for receiving an alternating current signal, and a second electrode that has at least one conducting surface being disposed to generate an input signal for a detecting device. The sensor further includes a middle electrode that has at least one conducting surface placed between the first electrode and the second electrode, as well as being grounded to a ground. The at least one conducting surface of the middle electrode, the at least one conducting surface of the first electrode, and the at least one conducting surface of the second electrode are contained within a holding material holding within itself the first electrode, the second electrode and the middle electrode.

Claims

1. A capacitive sensor comprising:

a first electrode having at least one conducting surface being disposed for receiving an alternating current signal;

a second electrode having at least one conducting surface being disposed to generate an input signal for a detecting device;

a middle electrode having at least one conducting surface placed between said first electrode and said second electrode, said middle electrode being connected to a ground; and

a holding material containing said at least one conducting surface of said middle electrode, said at least one conducting surface of said first electrode, and said at least one conducting surface of said second electrode;

a grounded metal surface greater in area then said first electrode, said middle electrode and said second electrode and positioned on a first side of said first electrode, said middle electrode and said second electrode;

said input signal varying in response to an object positioned proximate a second side of said first electrode, said middle electrode and said second electrode;

wherein said object comprises part of a human body.

2. The capacitive sensor of claim 1, wherein:

said holding material comprises a foam material.

3. The capacitive sensor of claim 1, wherein:

said first electrode, second electrode, and middle electrode all being flat conducting plates having predetermined thickness.

4. The capacitive sensor of claim 1, wherein:

said part of the human body comprises a hand.

5. The capacitive sensor of claim 1, wherein:

said grounded metal surface comprises a vehicle body plate.

6. The capacitive sensor of claim 1, wherein:

said input signal is indicative of a variation in a capacitance between said first electrode and said second electrode.

7. A capacitive sensor comprising:

a first electrode having at least one conducting surface being disposed for receiving an alternating current signal;

a second electrode having at least one conducting surface being disposed to generate an input signal for a detecting device;

a middle electrode having at least one conducting surface placed between said first electrode and said second electrode, said middle electrode being connected to a ground; and

a holding material containing said at least one conducting surface of said middle electrode, said at least one conducting surface of said first electrode, and said at least one conducting surface of said second electrode wherein;

said first electrode generating a flux of electric field, said flux comprising a first portion flux and a second portion flux;

said middle electrode disposed to receive said second position flux, said second portion flux passing substantially through said holding material;

said second electrode disposed to receive said first portion flux.

8. The capacitive sensor of claim 7, wherein:

said first portion flux comprising substantially only the flux which passes through a predetermined volume for utilization of proximity sensing.

9. The capacitive sensor of claim 7, wherein:

said second portion flux comprises substantially flux which does not exit the holding material.

10. A capacitive proximity sensing system, comprising:

a first electrode having at least one conducting surface being disposed for receiving an alternating current signal;

a second electrode having at least one conducting surface being disposed to generate an input signal;

a middle electrode having at least one conducting surface placed between said first electrode and said second electrode, said middle electrode being connected to a ground; and

a holding material containing said at least one conducting surface of said middle electrode, said at least one conducting surface of said first electrode, and said at least one conducting surface of said second electrode;

an oscillator coupled to said first electrode generating said alternating current signal; and

a detector receiving said input signal whereby an output of said detector being representative of a capacitance between said first electrode and said second electrode;

a grounded metal surface greater in area then said first electrode, said middle electrode and said second electrode and positioned on a first side of said first electrode, said middle electrode and said second electrode;

said input signal varying in response to an object positioned proximate a second side of said first electrode, said middle electrode and said second electrode;

wherein said object comprises part of a human body.

11. The capacitive proximity sensing system of claim 10, wherein:

said holding material comprises a foam material.

12. The capacitive proximity sensing system of claim 10, wherein:

said first electrode, second electrode, and middle electrode all being flat conducting plates having predetermined thickness.

13. The capacitive proximity sensing system of claim 10, wherein:

said part of the human body comprises a hand.

14. The capacitive proximity sensing system of claim 10, wherein:

said grounded metal surface comprises a vehicle body plate.

15. The capacitive proximity sensing system of claim 10, wherein:

said input signal is indicative of a variation in a capacitance between said first electrode and said second electrode.

16. A capacitive proximity sensing system, comprising:

a first electrode having at least one conducting surface being disposed for receiving an alternating current signal;

a second electrode having at least one conducting surface being disposed to generate an input signal;

a middle electrode having at least one conducting surface placed between said first electrode and said second electrode, said middle electrode being connected to a ground; and

a holding material containing said at least one conducting surface of said middle electrode, said at least one conducting surface of said first electrode, and said at least one conducting surface of said second electrode;

an oscillator coupled to said first electrode generating said alternating current signal; and

a detector receiving said input signal whereby an output of said detector being representative of a capacitance between said first electrode and said second electrode wherein;

said first electrode generates a flux of electric field, said flux comprising a first portion flux and a second portion flux;

said middle electrode disposed to receive said second portion flux, said second portion flux passing substantially through said holding material;

said second electrode disposed to receive said first portion flux.

17. The capacitive proximity sensing system of claim 16, wherein:

said first portion flux comprising substantially only the flux which passes through a predetermined volume for utilization of proximity sensing.

18. The capacitive proximity sensing system of claim 16, wherein:

said second portion flux comprises substantially flux which does not exit the holding material.