Distance measuring device and method for determining a distance

• US 6,445,191 B1
• Filed: 06/29/2000
• Issued: 09/03/2002
• Est. Priority Date: 07/31/1997
• Status: Expired due to Term

• Current Assignee: Cruise Munich GmbH
• Original Assignee: Mikrowellen-Technologie Und Sensoren GmbH
• Inventors: Trummer, Gunther
• Primary Examiner(s): Le, N.
• Assistant Examiner(s): LEROUX, ETIENNE PIERRE
• Application Number:
  US09/463,806
• Time in Patent Office: 796 Days
• Field of Search: 324/633, 324/635, 324/636, 735/143.1, 735/141.6, 333/227, 333/230, 333/231, 333/232, 257/664, 331/9, 331/97
• US Class Current: 324/635
• CPC Class Codes: F15B 15/12 of the oscillating-vane or curved-cylinder type
• CPC Class Codes: F15B 15/2869 using electromagnetic radiation, e.g. radar or microwaves

Abstract

Described is a distance-measuring device and a method for determining a distance, which uses a sensor in the form of a cavity resonator to continuously perform a distance determination and allows diverse possible uses.

Claims

1. Distance-measuring device with a sensor and an evaluation electronics unit for measuring distance to an object, wherein the sensor has a resonator in the form of a cavity resonator with a resonator housing, the resonator having a first surface for facing the object, a second surface being metallized, and a coplanar slot coupling with in-coupling line, and the in-coupling line being terminated at the resonator housing.

3. Distance-measuring device according to claim 1, wherein the resonator has a radiofrequency resonator whose resonance frequency is between 1 and 100 GHz.

4. Distance-measuring device according to claim 1, wherein the cavity resonator is cylindrical in shape, wherein the first surface is on a first end of the cylindrically-shaped resonator.

5. Distance-measuring device according to claim 1, wherein the cavity resonator is filled with a fluid material selected from the group of air and inert gas.

6. Distance-measuring device according to claim 1, characterized in that the cavity resonator is filled with a dielectric including Al₂O₃.

7. Distance-measuring device according to claim 6. wherein the cavity includes an attached piezoelectric ceramic, adapted to change its dielectric constant when loaded with pressure.

8. Distance-measuring device according to claim 6, wherein the cavity resonator is filled with dielectric material including piezoelectric ceramic, and the dielectric material has the property of changing the dielectric constant when loaded with pressure.

9. Distance-measuring device according to claim 6, wherein second surface is coated with a thin layer of gold.

10. Distance-measuring device according to claim 1 wherein the dielectric is inserted into a metal housing.

11. Distance-measuring device according to claim 1, wherein the coplanar slot coupling is disposed on a side of the resonator facing away from the object.

12. Distance-measuring device according to claim 11, wherein the coplanar slot coupling includes one coupling slot for each of a transmitter and receiver (transmission mode), the transmitter and receiver being disposed circularly.

13. Distance-measuring device according to claim 11, wherein the coplanar slot coupling includes one coupling slot for a transmitter and receiver (reflection mode).

14. Distance-measuring device according to claim 1, wherein the in-coupling line and the resonator allow as wave mode the H_0np modes.

15. Distance-measuring device according to claim 1, wherein the sensor includes a radio frequency electronics unit having a transmit branch and a receive branch.

16. Distance-measuring device according to claim 15, wherein the transmit branch consists of an oscillator.

17. Distance-measuring device according to claim 15, wherein the receive branch consists of at least one radiofrequency diode.

18. Distance-measuring device according to claim 16, wherein the oscillator frequency follows a setpoint frequency (reference input) via a closed control loop.

19. Distance-measuring device according to claim 18, wherein the control loop (PLL:

phase-locked loop) includes at least one frequency divider, a phase discriminator and a low-pass filter, and the setpoint frequency is prescribed via a DDS (direct digital synthesizer) (dynamic frequency control or determination).

20. Distance-measuring device according to claim 18, wherein the control loop consists of at least one frequency divider and is closed via a frequency counter, microcontroller and digital-to-analog converter (static frequency control or determination).

27. The device of claim 1, wherein the resonator is cylindrical in shape, wherein the first surface is on an end of the cylindrically-shaped resonator.

28. The device of claim 1, wherein the resonator has a resonance frequency of between 20 and 30 GHz.

29. The device of claim 1, wherein the resonator is a cavity resonator including a fluid material selected from the group of air and inert gas.

30. The device of claim 1, wherein the resonator is a cavity resonator including a dielectric material adapted to change the dielectric constant when loaded with pressure.

31. The device of claim 30, wherein the cavity resonator includes a dielectric material having the property of changing the dielectric constant when loaded with pressure.

32. The device of claim 1, wherein the second surface is metallized with gold.

33. The device of claim 1. wherein the electronics unit includes a coplanar slot coupling having an in-coupling line, the in-coupling line being terminated at the housing.

34. The device of claim 1, wherein the in-coupling line and the resonator are adapted to allow as the wave mode the H_0np modes.

35. The device of claim 1, wherein the electronics unit includes a microstrip line for the in-coupling, the microstrip line being terminated at the resonator housing.

36. The device of claim 1, wherein the electronics unit includes a piezoelectric ceramic material.

2. Distance-measuring device with a sensor and an evaluation electronics unit for measuring distance to an object, wherein the sensor has a resonator in the form of a cavity resonator with a resonator housing, the resonator having a first surface for facing the object, a second surface being metallized, and a microstrip line for the in-coupling, the microstrip line being terminated at the resonator housing.

21. Method for determining a distance to an object, comprising:

(a) providing a sensor and an evaluation electronics unit, the sensor including a cavity resonator with a resonator housing, the resonator having a first surface for facing the object. a second surface being metallized, and a coplanar slot coupling with in-coupling line, the in-coupling line being terminated at the resonator housing; and

(b) determining the resonance frequency of the cavity resonator in order to determine the distance to the object.

22. Method according to claim 21, wherein determining the resonance frequency includes detuning the transmit frequency of an oscillator in the transmit branch until a power dip at a resonance is found in the receive branch.

23. Method according to claim 22, wherein the transmit frequency of the oscillator is detuned by a ramp controller and a ramp generator.

24. Method according to claim 22, wherein the transmit frequency of the oscillator is adjusted via a direct digital synthesizer (DDS).

25. Method according to claim 21, including determining the resonance frequency in order to determine one selected from the group of pressure, force and mass on the object at zero distance to the object.

26. A device for measuring the distance to a conductive object, comprising:

(a) a resonator including a housing and a dielectric for detecting generating an electromagnetic wave in the presence of the conductive object, having a first surface for facing the object for measurement and a second surface being metallized; and

(b) an electronics unit attached to resonator and including a substrate adapted to couple electromagnetic waves generated by the resonator.