Sensor arrangement for capacitive position detection of an object

Patent metadata

Field	Value
Publication number	US-12221015-B2
Application number	US-202117796554-A
Country	US
Kind code	B2
Filing date	Jan 25, 2021
Priority date	Jan 30, 2020
Publication date	Feb 11, 2025
Grant date	Feb 11, 2025

Abstract

A sensor arrangement for capacitive detection of an object, including: an electrode arrangement having a heating element as an electrode; a detection device providing a detection signal to a sensor electrode and capacitively detecting the presence of an object near the sensor electrode; a high-side switch connected between a heating power source having a first potential and the heating element; a low-side switch connected between the heating element and a second potential; and a gate controller closing the high-side switch and low-side switch in a heating mode and opening the high-side switch and low-side switch in a detection mode. A decoupling MOSFET is connected between the high-side switch and heating element. The gate controller closes the MOSFET in the heating mode and opens the MOSFET in the detection mode. During the detection mode, the decoupling circuit provides a third potential at a first node between the high-side switch and MOSFET.

First claim

The invention claimed is:

1. A sensor arrangement for capacitive detection of an object, comprising:
an electrode arrangement comprising a heating element as an electrode;
a detection device that is adapted to apply a detection signal to a sensor electrode of the electrode arrangement and to capacitively detect the presence of an object in the proximity of the sensor electrode;
a high-side switch that is connected between a heating power source having a first potential and the heating element;
a low-side switch that is connected between the heating element and a second potential;
a gate controller that is adapted to close the high-side switch and the low-side switch in a heating mode and to open the high-side switch and the low-side switch in a detection mode; and
a decoupling circuit comprising a decoupling MOSFET connected between the high-side switch and the heating element, wherein the gate controller is adapted to close the decoupling MOSFET in the heating mode and to open the decoupling MOSFET in the detection mode, the decoupling circuit is adapted to actively provide a third potential at a first node during the detection mode, the first node is connected between the high-side switch and the decoupling MOSFET, and the first node is connected to a first DC voltage source via a first resistive element.

2. A sensor arrangement according to claim 1 , wherein the heating element is a guard electrode of the electrode arrangement.

3. A sensor arrangement according to claim 1 , wherein the heating element is a sensor electrode of the electrode arrangement.

4. A sensor arrangement according to claim 1 , wherein the sensor arrangement is adapted for hand detection on a steering wheel of a vehicle.

5. A sensor arrangement according to claim 1 , wherein the sensor arrangement is adapted for occupancy detection of a vehicle seat.

6. A sensor arrangement according to claim 1 , wherein at least one of the high-side switch and the low-side switch comprises a switch MOSFET.

7. A sensor arrangement according to claim 1 , wherein a body diode of the decoupling MOSFET has a forward direction opposite to the forward direction of body diodes of the high-side switch and the low-side switch.

8. A sensor arrangement according to claim 1 , wherein the decoupling MOSFET is an N-channel MOSFET.

9. A sensor arrangement according to claim 1 , wherein the decoupling MOSFET is a P-channel MOSFET.

10. A sensor arrangement according to claim 1 , wherein the decoupling circuit is adapted to actively provide a fourth potential to a second node between the heating element and the low-side switch during the detection mode.

11. A sensor arrangement according to claim 1 , wherein the gate controller is connected to the decoupling MOSFET via a third resistive element.

12. A sensor arrangement according to claim 1 , wherein the decoupling circuit is adapted to provide the third potential and a fourth potential so that at least one body diode of the decoupling MOSFET and the low-side switch is reverse biased in the detection mode.

13. A sensor arrangement for capacitive detection of an object, comprising:
an electrode arrangement comprising a heating element as an electrode;
a detection device that is adapted to apply a detection signal to a sensor electrode of the electrode arrangement and to capacitively detect the presence of an object in the proximity of the sensor electrode;
a high-side switch that is connected between a heating power source having a first potential and the heating element;
a low-side switch that is connected between the heating element and a second potential;
a gate controller that is adapted to close the high-side switch and the low-side switch in a heating mode and to open the high-side switch and the low-side switch in a detection mode; and
a decoupling circuit comprising a decoupling MOSFET connected between the high-side switch and the heating element, wherein the gate controller is adapted to close the decoupling MOSFET in the heating mode and to open the decoupling MOSFET in the detection mode, the decoupling circuit is adapted to actively provide a third potential at a first node during the detection mode, the first node is connected between the high-side switch and the decoupling MOSFET, and the first node is connected to ground via a capacitive element.

14. A sensor arrangement for capacitive detection of an object, comprising:
an electrode arrangement comprising a heating element as an electrode;
a detection device that is adapted to apply a detection signal to a sensor electrode of the electrode arrangement and to capacitively detect the presence of an object in the proximity of the sensor electrode;
a high-side switch that is connected between a heating power source having a first potential and the heating element;
a low-side switch that is connected between the heating element and a second potential;
a gate controller that is adapted to close the high-side switch and the low-side switch in a heating mode and to open the high-side switch and the low-side switch in a detection mode; and
a decoupling circuit comprising a decoupling MOSFET connected between the high-side switch and the heating element, wherein the gate controller is adapted to close the decoupling MOSFET in the heating mode and to open the decoupling MOSFET in the detection mode, the decoupling circuit is adapted to actively provide a third potential at a first node during the detection mode, the first node is connected between the high-side switch and the decoupling MOSFET, the decoupling circuit is adapted to actively provide a fourth potential to a second node between the heating element and the low-side switch during the detection mode, and the second node is connected to a second DC voltage source via a second resistive element.

Assignees

• Iee Sa

Inventors

• Lamesch Laurent
• Pampel Tobias
• Puetz Michael
• Rue Bertrand
• Vanstraelen Laurent

Classifications

• H05B3/0004

  Devices wherein the heating current flows through the material to be heated (Circuit arrangements for heating by passing the current directly across the material to be heated H05B3/0023; granular, powdered or fluid material H05B3/60) · CPC title

• H05B3/0023

  for heating by passing the current directly across the material to be heated · CPC title

• H03K17/74

  by the use, as active elements, of diodes (by the use of more than one type of semiconductor device H03K17/567; by the use of tunnel diodes H03K17/58; by the use of negative resistance diodes H03K17/70) · CPC title

• H03K17/687

  the devices being field-effect transistors · CPC title

• H05B3/0014

  Devices wherein the heating current flows through particular resistances · CPC title