Door/gate monitoring sensor device

• US 7,830,532 B2
• Filed: 06/04/2008
• Issued: 11/09/2010
• Est. Priority Date: 12/05/2005
• Status: Active Grant

• Current Assignee: Cedes AG (Assa Abloy AB)
• Original Assignee: Cedes AG (Assa Abloy AB)
• Inventors: De Coi, Beat
• Primary Examiner(s): Chowdhury; Tarifur
• Assistant Examiner(s): LAPAGE, MICHAEL P
• Application Number:
  US12/132,938
• Publication Number:
  US 20080304039A1
• Time in Patent Office: 888 Days
• Field of Search: 356/4.1, 356/5.09, 356/5.11, 356/622
• US Class Current: 356/622
• CPC Class Codes: G01S 17/04 Systems determining the presence of a target
• CPC Class Codes: G01S 17/87 Combinations of systems using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 7/497 Means for monitoring or calibrating
• CPC Class Codes: G01V 8/20 using multiple transmitters or receivers

Abstract

The invention proposes a sensor array having a plurality of sensor devices comprising a source of electromagnetic radiation, a receiver for the electromagnetic radiation and a control device, the control device being designed to use the source to emit electromagnetic radiation and being designed to determine a distance covered by electromagnetic radiation, which is emitted by the source, from a reflection surface of an object to the receiver by evaluating the reflected radiation. According to the invention, the sensor devices of the plurality of sensor devices operate at different frequencies or using time-division multiplexing. The invention also proposes a sensor device for a sensor array, the control device being designed to measure the distance at different frequencies or using time-division multiplexing.

Claims

1. A door/gate monitoring device having a sensor device comprising:

a first source for emitting electromagnetic radiation;

a receiver for receiving electromagnetic radiation; and

a control device for selecting a first frequency for the electromagnetic radiation to be emitted from the source for emitting electromagnetic radiation;

wherein, before emitting electromagnetic radiation, the sensor device determines whether signals are present that would interfere with the reception of the reflected electromagnetic radiation in a first frequency range that includes the first frequency,

when signals are not present that would interfere with the reception of the reflected electromagnetic radiation in the first frequency range, the sensor device causes the first source for emitting electromagnetic radiation to emit radiation at the first frequency and determines a distance covered by the electromagnetic radiation emitted by evaluating reflected electromagnetic radiation from a reflection surface of an object received at the receiver for receiving electromagnetic radiation;

when signals are present that would interfere with the reception of the reflected electromagnetic radiation in the first frequency range, the sensor device changes the selected frequency for the electromagnetic radiation to be emitted from the first source for emitting electromagnetic radiation to a second frequency and determines whether signals are present that would interfere with the reception of the reflected electromagnetic radiation in a second frequency range that includes the second frequency, and

when signals are not present that would interfere with the reception of the reflected electromagnetic radiation in the second frequency range, the sensor device causes the first source for emitting electromagnetic radiation to emit radiation at the second frequency and determine a distance covered by the electromagnetic radiation by evaluating reflected electromagnetic radiation from a reflection surface of an object received at the receiver for receiving electromagnetic radiation.

2. The door/gate monitoring device of claim 1, wherein the sensor device further comprises a second source for emitting electromagnetic radiation, wherein the first source for emitting electromagnetic radiation and the second source for emitting electromagnetic radiation emit electromagnetic radiation at different frequencies.

3. The device as claimed in claim 2, wherein the first source for emitting electromagnetic radiation and the second source for emitting electromagnetic radiation are light sources which operate at different frequencies.

4. The door/gate monitoring device of claim 1, wherein the control device changes a modulation frequency of the electromagnetic radiation.

5. The door/gate monitoring device of claim 1, wherein the control device changes a carrier frequency of the electromagnetic radiation.

6. The door/gate monitoring device of claim 1, wherein the control device varies a frequency of the electromagnetic radiation at least during a time period of a distance measurement.

7. The door/gate monitoring device of claim 1, wherein the control device maintains the frequency of the electromagnetic radiation constant at least during a time period of a distance measurement.

8. The door/gate monitoring device of claim 1, wherein the control device arbitrarily selects the first frequency for the electromagnetic radiation.

9. The door/gate monitoring device of claim 1, wherein the control device changes the frequency of the electromagnetic radiation to an arbitrarily selected frequency.

10. The door/gate monitoring device of claim 1, the sensor device further comprising manual setting means for selecting a frequency of the electromagnetic radiation.

11. The door/gate monitoring device of claim 1, wherein the control device automatically changes the selected frequency of the electromagnetic radiation after a predefined amount of time.

12. The door/gate monitoring device of claim 1, wherein the control device changes the frequency of the electromagnetic radiation on the basis of the extent to which interference is detected during a test.

13. The door/gate monitoring device of claim 1, wherein the receiver for receiving electromagnetic radiation and the first source for emitting electromagnetic radiation are matched to the frequency of the emitted electromagnetic radiation at the first frequency.

14. The door/gate monitoring device of claim 1, wherein the control device of the sensor device performs a first distance measurement in the second frequency range and a second distance measurement in a third frequency range, the measurement in the second frequency range providing an accurate but ambiguous measurement, and the second measurement in the third frequency range providing a measurement to remove the ambiguity from the first measurement.

15. The door/gate monitoring device of claim 1, wherein the control device determines the frequency to be selected on the basis of the distance to be measured.

16. The door/gate monitoring device of claim 1, wherein when electromagnetic radiation from another sensor device is present in a surrounding area, the sensor device determines an operating mode that prevents superimposition of measurements that would interfere with the reception of the reflected electromagnetic radiation.

17. The door/gate monitoring device of claim 1, wherein the control device of the sensor device is electrically connected to a control device of another sensor device, and prior to emitting electromagnetic radiation, the control device transmits a signal to the control device of the another sensor device to prevent the another sensor device from emitting electromagnetic radiation at the same time.

18. The device as claimed in claim 1, wherein the control device operates in a predefined mode when another sensor device emitting electromagnetic radiation at a different frequency is present in a surrounding area.

19. The door/gate monitoring device of claim 1, wherein the sensor device changes a modulation frequency and a carrier frequency of the electromagnetic radiation.