Monitoring circuit for a door

• US 20060033489A1
• Filed: 08/10/2005
• Published: 02/16/2006
• Est. Priority Date: 08/13/2004
• Status: Active Grant

• Current Assignee: Airbus Operations GmbH (Airbus SE)
• Original Assignee: Airbus Deutschland GmbH (Airbus SE)
• Inventors: Rieckmann, Norbert
• Granted Patent: US 7,414,530 B2
• Time in Patent Office: Days
• US Class Current: 324/207.170
• CPC Class Codes: G05B 23/0235 based on a comparison with predetermined threshold or range, e.g. "classical methods", carried out during normal operation; threshold adaptation or choice; when or how to compare with the threshold
• CPC Class Codes: G05B 9/02 electric

Abstract

The present application describes a monitoring circuit for an aircraft. The monitoring circuit comprises an inductive system, wherein the inductive system comprises a multitude of air core inductors and capacitors. Depending on the distance between a target and the inductive system the frequency response of the inductive system is changed. The change in the frequency response is detected and displayed in a display unit. The monitoring circuit can be used to improve door monitoring in an aircraft.

Claims

1. A monitoring circuit for monitoring a position of a target, comprising:

an inductive system;

wherein the inductive system comprises a plurality of air core inductors;

wherein the inductive system comprises a plurality of capacitors; and

wherein the inductive system is adapted such that depending on the distance between the target and the inductive system a frequency response of the inductive system changes.

2. The monitoring circuit of claim 1, further comprising:

a saw-tooth generator;

a voltage controlled oscillator;

wherein the saw-tooth generator and the voltage controlled oscillator constitute a sweep signal generator which cycles through a predetermined frequency spectrum;

wherein the sweep signal generator excites the inductive system with the frequency spectrum.

3. The monitoring circuit of claim 1, further comprising:

an evaluation unit;

wherein the evaluation unit is adapted to differentiate between at least two frequencies.

4. The monitoring circuit of claim 1, wherein the evaluation unit comprises:

a plurality of band filters;

wherein a centre frequency of a first band filter corresponds to a first frequency;

wherein a threshold value of the first frequency corresponds to a lower frequency of the inductive system at a first target position;

wherein the first band filter is adapted to allow a first signal with the first frequency to pass;

wherein the centre frequency of a second band filter corresponds to a second frequency;

wherein the second frequency corresponds to a resonating frequency of the inductive system at a second target position;

wherein the second band filter is adapted to allow a second signal with the second frequency to pass.

5. The monitoring circuit of claim 1, wherein the evaluation unit further comprises:

a plurality of comparators;

wherein the comparators supply output signals depending on a comparison between the first and the second signal.

6. The monitoring circuit of claim 1, further comprising:

a display unit;

wherein the display unit comprises luminous indicators;

wherein the luminous indicators display different target positions.

7. The monitoring circuit of claim 1, further comprising:

an alarm unit;

wherein the alarm unit issues an alarm at a predetermined target position.

8. The monitoring circuit of claim 1, wherein the monitoring circuit monitors an opening state of the door of a cargo hold of an aircraft.

9. A method of monitoring a position of a target, comprising the following steps:

providing an inductive system with a plurality of air core inductors and a plurality of capacitors;

making the target approach the air core inductors in such a way that the frequency response of the inductive system changes; and

evaluating the change in the frequency response for monitoring the door.