Capacitive distance sensor

Abstract

A capacitive distance sensor is provided. The distance sensor includes a sensor element having an electrically conductive, elongated, flat sensor area which in turn contains a number of holes. The sensor area is completely surrounded by an electrically non-conductive insulating body, with the result that the insulating body completely covers the edge regions of the holes. The sensor element is produced, in particular, by first of all making the holes in the sensor area. In a subsequent step, the sensor area is completely encased by the insulating body which also completely fills the holes in the sensor area.

Claims

1. A capacitive distance sensor comprising: a sensor element that comprises an electrically conductive, elongated, flat sensor surface, a plurality of holes formed in the sensor surface; and an electrically nonconductive insulating body completely enclosing the sensor surface such that the insulating body completely covers edge regions of the holes wherein the insulating body is in contact with all surfaces of the flat sensor surface.

2. The capacitive distance sensor as claimed in claim 1, wherein the holes are configured as elongated holes and wherein comparatively long axes of the elongated holes extend in a longitudinal direction of the sensor surface.

3. The capacitive distance sensor as claimed in claim 1, wherein the sensor element is flexible.

4. The capacitive distance sensor as claimed in claim 1, wherein the sensor surface is composed of copper.

5. The capacitive distance sensor as claimed in claim 1, wherein at least a portion of the insulating body is composed of PVC.

6. The capacitive distance sensor as claimed in claim 1, wherein the insulating body contains a plurality of cutouts corresponding to the plurality holes, and wherein each cutout extends within one of the holes.

7. The capacitive distance sensor as claimed in claim 6, wherein a cross-sectional area of each cutout has substantially a same shape as that of the respective corresponding hole through which the cutout extends.

8. A method for manufacturing a sensor element for a capacitive distance sensor as claimed in claim 1, the method comprising: forming a plurality of holes in the flat, elongated sensor surface, composed of the electrically conducive material; completely enclosing, in a subsequent working step, the sensor surface by an insulating body which is composed of an electrically nonconductive material and which also completely fills the holes of the sensor surface.

9. The method for manufacturing a sensor element as claimed in claim 8, wherein, in a subsequent working step, a plurality of cutouts corresponding to the plurality of holes is made in the insulating body such that each cutout runs within one of the holes, and wherein an edge of the cutout is consistently at a distance from an edge of an associated hole.

10. The capacitive distance sensor as claimed in claim 1, wherein the insulating body directly contacts all surfaces of the flat sensor surface.

11. The capacitive distance sensor as claimed in claim 1, wherein the insulating body bears against all surfaces of the flat sensor surface.

12. The capacitive distance sensor as claimed in claim 1, further comprising a macromelt termination cast on an end of the flat sensor surface.

13. A sensor element, comprising: an electrically conductive, elongated, flat sensor-surface; a plurality of holes formed in the sensor surface; and an electrically nonconductive insulating body completely enclosing the sensor surface such that the insulating body completely covers edge regions of the holes wherein the insulating body is in contact with all surfaces of the flat sensor.

14. The capacitive distance sensor as claimed in claim 1, further comprising a plurality of fasteners disposed in the plurality of holes.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:

(2) FIG. 1 is a schematic view of a capacitive distance sensor with an elongated sensor element, and

(3) FIG. 2 shows a detail of the sensor element in a perspective view.

DETAILED DESCRIPTION

(4) Corresponding parts are provided with the same reference symbols in all the figures.

(5) FIG. 1 is a schematic view of a capacitive distance sensor 2. The distance sensor 2 comprises an elongated, flexible sensor element 4, electronics 6 and a connecting line 8 which connects the sensor element 4 electrically to the electronics 6. For example, the distance sensor 2 is located inside a motor vehicle. In particular, within the scope of a keyless automatic starting system (Keyless-Go) the approaching of the parked motor vehicle by a person is monitored by means of the distance sensor 2. In one expedient application case, the sensor element 4 is mounted in the rear region of the motor vehicle, for example on the rear bumper 10. The longitudinal direction 12 of the sensor element 4 suitably runs parallel to the wheel axes of the vehicle.

(6) The electronics 6 supply the sensor element 4 with current and evaluate the measurement data of the sensor element 4. In particular, on the basis of a signal emitted by the distance sensor 2, the rear tailgate of the motor vehicle can be opened, with the result that the approaching person does not have to perform any manual activity to open the tailgate.

(7) FIG. 2 illustrates the sensor element 4 in more detail. As is apparent from the illustration, the sensor element 4 comprises an insulating body 14 into which a sensor surface 16 is embedded in such a way that the sensor surface 16 is completely enclosed by the insulating body 14. The insulating body 14 bears in a positively locking fashion against the sensor surface 16, for example in order to avoid displacement of the sensor surface 16 with respect to the insulating body 14 and/or in order to increase the stability of the sensor element 4. The sensor surface 16 which is composed, for example, of copper is elongated and flat and is, in particular, in the shape of a strip. A number of holes 18 are punched into the sensor surface 16. The holes 18 are in the shape of an elongated hole, wherein the long axes of the elongated holes extend along the longitudinal direction 12 of the sensor surface 16. The center points of the holes 18 are located on a straight line which extends in the longitudinal direction 12 of the sensor surface 16 and is located centrally on the sensor surface 16.

(8) The insulating body 14 which is composed, in particular, of PVC is in the shape of a flat cuboid, wherein two surfaces are parallel to the sensor surface 16. The insulating body 14 has, for example, a length of approximately 63 cm, a width of approximately 3 cm and a thickness of approximately 0.2 cm. A cutout 20 of the insulating body 14 runs within each hole 18 of the sensor surface 16. The shape of the cutouts 20 corresponds essentially to that of the holes 18. The edge region 22 of the holes 18 is filled by the insulating body 14. In the mounted state of the distance sensor 2, for example in each case a screw 24 can be located within the cutouts 20, which screw 24 is used to attach the sensor element 4 to an object.

(9) A termination 26 (FIG. 1) is located at one end of the sensor element 4. The body of the termination 26 is composed of macromelt and is cast onto the sensor element 4. A connecting point 28, at which the sensor element 4 is electrically in contact with the connecting line 8, is embedded in the termination 26.

(10) The holes 18 are firstly punched into the sensor surface 16 within the course of the manufacture of the sensor element 4. In a subsequent working step, the sensor surface 16 is encased completely by the insulating body 14. The cutouts 20 are subsequently formed in the insulating body 14.

(11) The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.