Proximity detector comprising capacitive sensor

• US 20060097734A1
• Filed: 09/05/2003
• Published: 05/11/2006
• Est. Priority Date: 09/06/2002
• Status: Active Grant

• Current Assignee: Fogale Sensors
• Original Assignee: Nanotec Corporation
• Inventors: Roziere, Didier
• Granted Patent: US 7,570,064 B2
• Time in Patent Office: Days
• US Class Current: 324/662
• CPC Class Codes: A61B 6/102 Protection against mechanical damage, e.g. anti-collision devices
• CPC Class Codes: G01B 7/023 for measuring distance between sensor and object G01B7/082 and G01B7/102 take precedence
• CPC Class Codes: H03K 17/955 using a capacitive detector

Abstract

A proximity detector employs a capacitive sensor, having: at least one detection antenna including numerous capacitive proximity sensors which each include a measuring electrode, the antenna being positioned close to an object or body; electronic elements for exciting the electrodes and processing the distance measurement signals originating from the capacitive sensors; and digital elements of controlling the electronic elements and of calculating the distances between the electrodes and the body or object using the processed measurement signals. The detection antenna also contains a single guard for all of the measuring electrodes. Moreover, the electronic elements have, for each detection antenna, a floating or floating excitation capacitive bridge which co-operates with polling elements in order sequentially to measure the respective capacitances between each electrode and the object or body to be measured.

Claims

1. Proximity detector employing a capacitive sensor, comprising:

at least one detection antenna comprising a plurality of capacitive proximity sensors, each comprising a measurement electrode, said antenna being placed close to an object or a body,

electronic means for exciting said measurement electrodes and for processing the signals originating from said capacitive sensors,

digital means for controlling the electronic means and for calculating, from the measurement signals thus processed, the distances between said electrodes and said object or said body,

characterised in that the electronic means comprise, for each detection antenna, a floating capacitive bridge or with floating excitation, cooperating with polling means to measure sequentially the respective capacitances between each electrode of said antenna and the object or body to be measured.

2. Proximity detector according to claim 1, characterised in that the detection antenna also comprises a single shield for all the measurement electrodes of the antenna.

3. Proximity detector according to claim 1, characterised in that the detection antenna also comprises a number of shields each provided for a part of the assembly of measurement electrodes of the antenna.

4. Proximity detector according to claim 1, characterised in that the electronic means and the digital control and calculation means cooperate to measure a distance successively on each electrode of an antenna according to a predetermined but changeable order.

5. Proximity detector according to claim 1, characterised in that at least one of its detection antennas comprises a test track which, in normal operation, is at the potential of the shield and, in test mode, is earthed.

6. Proximity detector according to claim 5, characterised in that the test track is placed to the rear of or close to the electrodes.

7. Proximity detector according to claim 1, characterised in that the electronic means and the digital control and calculation means cooperate to deliver an alarm signal indicating an inconsistent measurement or a malfunction of the digital control and calculation means.

8. Proximity detector according to claim 1, characterised in that the electronic means also comprise one or more reference capacitances provided to check the calibration of said electronic means or to recalibrate said electronic means.

9. Proximity detector according to claim 1, characterised in that one antenna also comprises, close to the measurement electrodes, one or more shield or earthing surfaces which are arranged to modify the field lines of the measurement electrodes.

10. Proximity detector according to claim 1, characterised in that it is arranged on the inside or outside surface of a cap or box and comprises a plurality of measurement areas equipped with detection antennas.

11. Proximity detector according to claim 1, characterised in that the electronic means and the digital control and calculation means cooperate to deliver proximity detection threshold signals.

12. Proximity detector according to claim 10, characterised in that the electronic means and the digital control and calculation means cooperate to deliver analogue output signals of minimum distance images between the zones of the box and the objects detected.

13. Proximity detector according to claim 10, characterised in that the antennas are arranged on five faces of the box or cap.

14. Proximity detector according to claim 10, characterised in that it comprises edge antennas arranged in part over one face of said cap, and in part over another contiguous face, and lateral antennas.

15. Proximity detector according to claim 1, characterised in that at least one of the antennas is produced using a flexible circuit.

16. Proximity detector according to claim 1, characterised in that at least one of the antennas is connected to the electronic means by flexible connecting means.

17. Proximity detector according to claim 1, used in a piece of radiology equipment employing X-rays, comprising a device for emitting an X-ray beam intended to irradiate an object or a body and a device for detecting the X-rays originating from said object or body, this X-ray detector device being covered by a cap, characterised in that the detector is arranged on the inside or outside surface of said cap, in the X-ray emission field and in that it comprises at least one antenna, termed the X-ray antenna, crossed by the X-ray beam.

18. Proximity detector according to claim 17, characterised in that the X-ray antenna comprises a piercing provided for the passage of the X-ray beam.

19. Proximity detector according to claim 17, characterised in that the X-ray antenna is produced from a flexible printed circuit composed of an insulator metallised on both faces with a thin layer of chromium then by a layer of copper, said copper layer being removed over an area which corresponds to the passage of the X-ray beam and in which the linking tracks and the capacitive electrodes are produced from the chromium layer.

20. Proximity detector according to claim 1, fitted in a piece of radiology equipment employing X-rays, comprising a device for emitting an X-ray beam intended to irradiate an object or a body, characterised in that it is arranged on the inside or outside surface of said emitter device.

21. Application of a proximity detector according to claim 1, for controlling a vascular positioner.

22. Application of a proximity detector according to claim 1, in a radiology machine, for checking the X-ray dose emitted on to an object or a body, starting from a calculation of the thickness of said object or body.

23. Application according to claim 22, in which the thickness of the object or body is calculated from distance measurements.

24. Application of a proximity detector according to claim 1, for checking the speed and/or position of a machine in motion, in particular a machine tool.

25. Application of a proximity detector according to claim 1, for detecting a complex shape or a presence.

26. Application according to claim 25, in which one or more proximity detectors are installed in an item of equipment or a moving vehicle.

27. Application according to claim 25, in an anti-burglary detector.

28. Application of at least one proximity detector according to claim 1, for the production of a capacitive camera for the measurement of a object or human body topography.

29. Application of at least one proximity detector according to claim 1, for the production of image in three dimensions of human body.

30. Application of at least one proximity detector according to claim 1, for the detection of a part of human body as a hand.