MAGNETIC SENSOR

• US 20170131356A1
• Filed: 11/11/2016
• Published: 05/11/2017
• Est. Priority Date: 11/11/2015
• Status: Active Grant

• Current Assignee: Melexis Technologies NV (Sensinnovat BVBA)
• Original Assignee: Melexis Technologies NV (Sensinnovat BVBA)
• Inventors: BOURY, Bruno
• Granted Patent: US 10,488,464 B2
• Time in Patent Office: Days
• CPC Class Codes: G01R 31/3274 Details related to measuring, e.g. sensing, displaying or computing; Measuring of variables related to the contact pieces, e.g. wear, position or resistance measuring contact resistance G01R27/205
• CPC Class Codes: G01R 31/3275 Fault detection or status indication
• CPC Class Codes: G01R 33/00 Arrangements or instruments for measuring magnetic variables
• CPC Class Codes: G08B 13/08 by opening, e.g. of door, of window, of drawer, of shutter, of curtain, of blind
• CPC Class Codes: G08B 13/24 by interference with electromagnetic field distribution
• CPC Class Codes: G08B 29/046 prevention of tampering with detection circuits
• CPC Class Codes: H01H 36/0073 actuated by relative movement between two magnets

Abstract

A sensor circuit for sensing a circuit change, e.g. circuit break, is described. It comprises a permanent or electro magnet for generating a magnetic field, a sensing system comprising one or more magnetic sensors configured for sensing an at least one dimensional magnetic field from the permanent magnet and for providing an output signal representative of said at least one dimensional magnetic field. The circuit also comprises a controller for detecting an event by comparing said output signal with reference data, said reference data comprising for at least one direction of said magnetic field a reference range having an upper boundary and a lower boundary wherein the upper boundary and lower boundary are magnetically unipolar.

Claims

1. A sensor circuit for sensing a circuit change, e.g. circuit break, the sensor circuit comprising:

a permanent or electro magnet for generating a magnetic field,

a sensing system comprising one or more magnetic sensors configured for sensing the magnetic field at least in one direction, and for providing an output signal representative of said sensed magnetic field in the at least one direction, and

a controller for detecting an event by comparing said output signal with reference data, said reference data comprising for at least one direction of said magnetic field a reference range having an upper boundary and a lower boundary wherein the upper boundary and lower boundary are magnetically unipolar.

2. A sensor circuit according to claim 1, wherein comparing said output signal with said reference data comprises, for a magnetic field sensed in at least one direction, evaluating whether values for at least one direction of said sensed magnetic field fall within said reference range having an upper boundary and a lower boundary which are magnetically unipolar.

3. A sensor circuit according to claim 1, wherein said reference data comprises for more than one direction, e.g. in two distinct directions or in three distinct directions, a reference range having an upper boundary and a lower boundary wherein the upper boundary and lower boundary are magnetically unipolar.

4. A sensor circuit according to claim 1, wherein said controller is furthermore adapted for dynamically adjusting said reference data to conditions of the sensing system in use.

5. A sensor circuit according to claim 4, wherein the boundary values of the reference range are programmably settable by the user, at factory level or at runtime level.

6. A sensor circuit according to claim 1, wherein said sensing system for sensing said at least one dimensional magnetic field is a sensing system for sensing an at least two dimensional magnetic field or a three dimensional magnetic field.

7. A sensor circuit according to claim 1, wherein the sensing system for sensing the magnetic field has a gain adjustment which compensates for the variation in magnetic remanence of a permanent magnet over temperature employed in the system.

8. A sensor circuit according to claim 1, wherein the sensing system comprises a single sensor for sensing a two or three dimensional magnetic field.

9. A sensor circuit according to claim 1, wherein the sensor circuit comprises a power unit configured for automatically activating magnetic measurement at programmable time intervals without the need for an external trigger before each measurement.

10. A sensor circuit according to claim 1, the sensor circuit furthermore comprising an RF receiver, wherein the system is configured for using a trigger from the RF receiver to the magnetic sensing system for memorizing the magnetic environment of the sensor circuit and/or the sensor circuit comprising an RF transmitter, wherein the system is configured for transmission of a detection event by the one or more sensors of the sensing system.

11. A sensor circuit according to claim 10, wherein the RF receiver and RF transmitter is combined in a single RF transceiver and/or is combined with one of the sensor elements.

12. A sensor circuit according to claim 1, wherein the magnetic sensor is configured for measuring a supply voltage and for sending a control signal for indicating a low energy status of a local powering source.

13. A sensor circuit according to claim 1, wherein the sensor circuit is configured for comparing digitally or in an analog way a sensing signal from the sensing system with a threshold.

14. A sensor circuit according to claim 13, the sensor circuit comprising an interrupter, wherein the output of the comparison is directly connected to the sensor circuit interrupter.

15. A sensor circuit according to claim 1, wherein the permanent magnet or the electromagnetic magnet has a fixed position with respect to the one or more sensors, the sensor circuit furthermore comprising a ferromagnetic target changing the magnetic field seen by the sensor when the target is moved.

16. Use of a sensor circuit according to claim 1 for security applications, e.g. home security applications.

20. A security system comprising a sensor circuit according to claim 1.

17. A method for sensing a circuit break, the method comprising

inducing a permanent magnetic field,

sensing said permanent magnetic field and providing an output signal representative of said permanent magnetic field, and

detecting an event by comparing said output signal with reference data, said comparing comprising comparing an output signal representative of values of the sensed magnetic field in at least one direction with a reference range having an upper boundary and a lower boundary wherein the upper boundary and lower boundary are magnetically unipolar.

18. A method according to claim 17, wherein comparing said output signal with said reference data comprises, for a sensed magnetic field sensed in at least one direction, evaluating whether values for at least one direction of said sensed magnetic field fall within said reference range having an upper boundary and a lower boundary which are magnetically unipolar.

19. A method according to claim 17, wherein said method comprises dynamically adjusting said reference data to conditions of the sensing system in use and/or dynamically adjusting the boundary values of said one or more reference ranges at runtime level.