CAPACITIVE SENSOR ARRAY

• US 20110012623A1
• Filed: 07/15/2010
• Published: 01/20/2011
• Est. Priority Date: 07/20/2009
• Status: Active Grant

• Current Assignee: Huf Hulsbeck & Furst GmbH & Co. KG
• Original Assignee: Huf Hulsbeck & Furst GmbH & Co. KG
• Inventors: Gastel, Peter Van, Lindic, Iko
• Granted Patent: US 8,344,739 B2
• Time in Patent Office: Days
• US Class Current: 324/686
• CPC Class Codes: B60R 19/48 combined with, or convertible into, other devices or objects, e.g. bumpers combined with road brushes, bumpers convertible into beds
• CPC Class Codes: H03K 17/955 using a capacitive detector

Abstract

A capacitive sensor array includes a sensor electrode, a shielding electrode and a background electrode which are surrounded by insulator materials and connected to a control and evaluation circuit. Using the sensor electrode that extends along a first coordinate line, the entry of an object into a space ahead of the sensor electrode is detected. The control and evaluation circuit detects a capacity change of the sensor electrode as compared to a reference potential. The shielding electrode is connected to the sensor electrode via the control and evaluation circuit in such a manner that its potential follows. The three electrodes are arranged behind each other along a second coordinate line that is perpendicular to the first coordinate line. The insulating materials are arrayed between the sensor electrode and the detection zone. The central axis of the cylinder lies within the plane that is formed by the first and second coordinate lines. The insulator materials between the detection zone and the sensor electrode include at least one plastic layer that directly surrounds the sensor electrode and a plastic layer that is arrayed at a specified distance. The insulator materials are arranged so that the relative dielectricity constant initially assumes a relatively high value of the surrounding plastic layer as the distance from the sensor electrode increases, then drops to a value that approaches the value of 1, and then again rises to a relatively high value of the outer plastic layer.

Claims

1. Capacitive sensor array including

a sensor electrode that extends along a first coordinate line, which is to be used to detect the entry of an object into a space ahead of the sensor electrode,

a control and evaluation circuit that is linked to the sensor electrode and detects a capacity change in the capacity of the sensor electrode as compared to a reference potential by periodically charging and discharging the sensor electrode with a predetermined frequency and evaluating at least one parameter of a current or voltage progression that is dependent on the periodic charging and discharging of the sensor electrode in order to detect the capacity change,

a background electrode that extends parallel to the sensor electrode,

a shielding electrode that is arranged between the sensor electrode and the background electrode and that is linked to the sensor electrode via the control and evaluation circuit in such a manner that its potential largely follows the potential of the sensor electrode,

wherein the sensor electrode, the shielding electrode and the background electrode are arranged behind each other along a second coordinate line that is perpendicular to the first coordinate line, wherein a detection area of the sensor array extends into the direction of the second coordinate line into the space ahead of the sensor electrode and within a specified angle area (a) to both sides of the plane that is formed by the first and second coordinate lines,

wherein the sensor electrode is surrounded by insulating materials which are arrayed between the sensor electrode and the detection zone in the manner of a semicircular or semi-elliptical cylinder, wherein the central axis of the cylinder lies within the plane that is formed by the first and second coordinate lines, wherein the insulator materials between the detection zone and the sensor electrode include at least one plastic layer of a first thickness that directly surrounds the sensor electrode and a plastic layer of a second thickness that is arrayed at a specified distance, wherein the insulator materials are arranged so that the relative dielectricity constant initially assumes a relatively high value of the surrounding plastic layer as the distance from the sensor electrode increases, then drops to a value that approaches the value of 1 (for instance the value of air), and then again rises to a relatively high value of the outer plastic layer.

2. Capacitive sensor array in accordance with claim 1, whereby there is a gas filled space between the plastic layer surrounding the sensor electrode and the outer plastic layer, whose width corresponds to the specified distance and whose relative dielectricity constant approximates the value of 1.

3. Capacitive sensor array in accordance with claim 2, whereby the gas filled space is formed by an air gap or several air gaps with radial and/or cylindrical plastic dividing walls.

4. Capacitive sensor array in accordance with claim 2, whereby the gas filled space is formed by a foamed plastic area.

5. Capacitive sensor array in accordance with claim 1, whereby the plastic layer surrounding the sensor electrode and/or the outer plastic layer each consist of several plastic layers.

6. Capacitive sensor array in accordance with claim 1, whereby the specified distance between the plastic layer surrounding the sensor electrode and the outer plastic layer lies within the range of 30% to 90%, preferably within the range from 50% to 70%, of the distance of the outer surface of the outer plastic layer from the surface of the sensor electrode.

7. Capacitive sensor array in accordance with claim 1, whereby the first thickness and the second thickness lie within the range between 0.2 mm and 2 mm.

8. Capacitive sensor array in accordance with claim 1, whereby the specified distance between the plastic layer surrounding the sensor electrode and the outer plastic layer lies within the range of 0.5 mm and 10 mm, preferably within the range from 1 mm to 4 mm.

9. Capacitive sensor array in accordance with claim 1, whereby the detection area of the sensory array extends within a specified angle area (a) ranging from 40°

to 130°

to both sides of the plane formed by the first and second coordinate lines.

10. Capacitive sensor array in accordance with claim 1, whereby the sensor electrode on the side facing the shielding electrode as well as the shielding electrode and the background electrode are surrounded by a plastic mantle, wherein the plastic mantle supports the electrodes and fixes their position.

11. Capacitive sensor array in accordance with claim 1, whereby the background electrode is formed as a level plate that is symmetrically arranged at a plane that is perpendicular to the second coordinate line behind the sensor electrode.

12. Capacitive sensor array in accordance with claim 11, whereby the background electrode extends into the direction that is perpendicular to the first and second coordinate lines to the outer plastic layer of the insulator materials that are arranged in the manner of a semicircular or semi-elliptical cylinder.

13. Capacitive sensor array in accordance with claim 11, whereby the shielding electrode possesses a width in the direction that is perpendicular to the first and second coordinate lines which is greater than that of the sensor electrode, however lesser than that of the background electrode.

14. Capacitive sensor array in accordance with claim 1, whereby the reference potential is mass and the background electrode is a mass electrode.

15. Capacitive sensor array in accordance with claim 1, whereby the specified frequency lies within the range from 50 kHz to 5 MHz, preferably between 100 kHz and 1 MHz.