# US 8,150,639 B2 · Magnetic field sensor

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- Number: US 8,150,639 B2
- Document ID: US8150639B2
- Status: Granted
- Kind: B2
- Application number: 12/306,028
- Filed: 2007-05-25
- Published: 2009-11-12
- Granted: 2012-04-03
- Earliest claimed: 2006-06-21
- Assignees: NXP B.V.
- Inventors: Teunis Ikkink; Hans Boeve
- Web page: https://patentgrep.com/patent/US8150639B2

## CPC

- G01C 17/38: Testing, calibrating, or compensating of compasses
- G01C 17/00: Compasses; Devices for ascertaining true or magnetic north for navigation or surveying purposes (using gyroscopic effect G01C19/00)
- G01C: MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY (measuring liquid level G01F; radio navigation, determining distance or velocity by use of propagation effects, e.g. Doppler effects, propagation time, of radio waves, analogous arrangements using other waves G01S)

## Abstract

Magnetic field sensors (1) comprising field detectors (10) for detecting magnetic fields are provided with environment detectors (11) for detecting environments and with processors (12) for, in response to detected environments, performing processes such as loading calibration parameter sets and (re)calibrations for the field detectors (10), to allow the magnetic field sensors (1) to be used in different subsequent environments. The environment detectors (11) may comprise code detectors for detecting codes indicative for environments and may comprise user interfaces (13) for, in response to detected environments and via user interactions, selecting processes to be performed by the processors (12). Devices (2) comprise magnetic field sensors (1). Apparatuses (3) such as cradles removably fix the devices (2) and may comprise code generators (30) for generating the codes indicative for the environments.

## Claims

### Claim 1

A magnetic field sensor comprising:
a field detector, comprising an accelerometer, for detecting a magnetic field and for, in response to a field detection result, outputting an indication signal;
a code generator for generating a code indicative for a magnetic environment;
an environment detector comprising a code detector for detecting the code indicative for the magnetic environment and for, in response to a first environment detection result, outputting a first result signal and for, in response to a second environment detection result different from the first environment detection result, outputting a second result signal different from the first result signal; and
a processor for, in response to the first result signal, performing a first process for the field detector and for, in response to the second result signal, performing a second process for the field detector, which second process is different from the first process.

### Claim 2 (depends on 1)

The magnetic field sensor according to claim 1, wherein at least one of the processes comprises the loading of a calibration parameter set.

### Claim 3 (depends on 1)

The magnetic field sensor according to claim 1, wherein at least one of the processes comprises a recalibration of the field detector based upon signals from the accelerometer.

### Claim 4 (depends on 1)

The magnetic field sensor according to claim 1, the environment detector being arranged to, in response to a third environment detection result, outputting a third result signal different from the first and second result signals, and the processor being arranged to, in response to the third result signal, performing a third process for the field detector, which third process is different from the first and second processes.

### Claim 5 (depends on 1)

The magnetic field sensor according to claim 1, further comprising:
a user interface for, in response to at least one result signal, selecting at least one process to be performed by the processor.

### Claim 6 (depends on 5)

The magnetic field sensor of claim 5, wherein the user interface further comprises a display.

### Claim 7 (depends on 5)

The magnetic field sensor of claim 5, wherein the user interface further comprises a loudspeaker.

### Claim 8 (depends on 5)

The magnetic field sensor of claim 5, wherein the user interface displays the indication signal from the field detector.

### Claim 9 (depends on 1)

A device comprising the magnetic field sensor according to claim 1.

### Claim 10 (depends on 9)

An apparatus for removably fixing the device according to claim 9.

### Claim 11 (depends on 10)

The apparatus according to the claim 10, the apparatus being a cradle and the device being insertable into the cradle.

### Claim 12 (depends on 1)

The magnetic field sensor of claim 1, wherein the environment detector further comprises a metal detector.

### Claim 13 (depends on 12)

The magnetic field sensor of claim 12, wherein detection of a changed amount of metal by the metal detector prompts a recalibration.

### Claim 14

A method for magnetic field sensing, comprising the steps of:
detecting a magnetic field with a magnetic field sensor comprising an accelerometer;
in response to a magnetic field detection result, outputting an indication signal;
generating a code indicative of a magnetic environment;
detecting the code indicative of the magnetic environment;
in response to a first environment detection result, outputting a first result signal;
in response to a second environment detection result different from the first environment detection result, outputting a second result signal different from the first result signal;
in response to the first result signal, performing a first process for the field detection; and
in response to the second result signal, performing a second process for the field detection, which second process is different from the first process.

### Claim 15 (depends on 14)

A non-transitory computer readable medium containing computer instructions stored therein for causing a computer processor to perform the steps of the method according to claim 14.