Magnetic field sensor

• US 10,249,161 B2
• Filed: 07/25/2014
• Issued: 04/02/2019
• Est. Priority Date: 07/25/2014
• Status: Active Grant

• Current Assignee: 1010210 BC Ltd.
• Original Assignee: 1010210 BC Ltd.
• Inventors: Carlson, Julian
• Primary Examiner(s): Natalini, Jeff
• Assistant Examiner(s): Yeninas, Steven
• Application Number:
  US14/341,710
• Publication Number:
  US 20160027272A1
• Time in Patent Office: 1,712 Days
• Field of Search: 324252, 32420711, 3242072, 32420721, 32420726, 340501, 340511, 340541, 3405451, 340542, 340547, 340551, 340567, 3406861, 340686, 3405453, 3406866
• CPC Class Codes: G01R 33/0023 Electronic aspects, e.g. circuits for stimulation, evaluation, control; Treating the measured signals; calibration G01R33/0017 takes precedence
• CPC Class Codes: G01R 33/02 Measuring direction or magnitude of magnetic fields or magnetic flux G01R33/20 takes precedence
• CPC Class Codes: G01V 3/081 the magnetic field is produced by the objects or geological structures characterised by the method of magnetic field measurement G01R33/00
• CPC Class Codes: G08B 13/24 by interference with electromagnetic field distribution
• CPC Class Codes: G08B 13/2491 Intrusion detection systems, i.e. where the body of an intruder causes the interference with the electromagnetic field
• CPC Class Codes: G08B 3/10 using electric transmission; using electromagnetic transmission
• CPC Class Codes: G08B 5/36 using visible light sources
• CPC Class Codes: G08B 6/00 Tactile signalling systems, e.g. personal calling systems

Abstract

A magnetic field sensor comprises a power source, an indicator and a microprocessor. The power source supplies current to the indicator. The indicator turns on when a magnetic field is sensed and the indicator turns off when a magnetic field is not sensed. The microprocessor renders the indicator inoperable a predetermined period of time after the magnetic field sensor is powered up.

Claims

1. A magnetic field sensor comprising:

a housing having a lid;

a tamper switch which detects when the lid of the housing is opened;

a device which senses a presence or an absence of a magnetic field;

a power source, the magnetic field sensor being powered up when the lid of the housing is removed and the power source is inserted into the housing;

a microprocessor, a signal being sent by the tamper switch to the microprocessor when the lid of the housing is open, and a signal being sent by the device to the microprocessor when a magnetic field is sensed; and

an indicator which indicates the presence or the absence of a magnetic field, wherein the power source supplies current to the indicator, and the indicator turns on when a magnetic field is sensed and turns off when a magnetic field is not sensed; and

wherein the indicator is initially operable following the power source being inserted into the housing and the magnetic field sensor being powered up, and the microprocessor renders the indicator inoperable a predetermined period of time after the lid of the housing is closed following the power source being inserted into the housing and the magnetic field sensor being powered up, and the indicator remaining inoperable until the lid of the housing is removed and the lid of the housing is closed again at which point the indicator is operable until the microprocessor again renders the indicator inoperable a predetermined period of time after the lid of the housing is closed again.

2. The magnetic field sensor as claimed in claim 1 wherein the indicator is an auditory indicator.

3. The magnetic field sensor as claimed in claim 1 wherein the indicator is a vibratory indicator.

4. The magnetic field sensor as claimed in claim 1 wherein the indicator is a visual indicator.

5. The magnetic field sensor as claimed in claim 4 wherein the indicator comprises a light emitting diode.

6. The magnetic field sensor as claimed in claim 1 wherein the power source is a coin cell battery.

7. The magnetic field sensor as claimed in claim 1 further including a supercapacitor.

8. The magnetic field sensor as claimed in claim 1 further including a radio and an antenna.

9. A proximity sensor including a magnet which generates a magnetic field and a magnetic field sensor, the magnetic field sensor comprising:

a housing having a lid;

a tamper switch which detects when the lid of the housing is opened;

a device which senses a presence or an absence of a magnetic field;

a power source, the magnetic field sensor being powered up when the lid of the housing is removed and the power source is inserted into the housing;

a microprocessor, a signal being sent by the tamper switch to the microprocessor when the lid of the housing is open, and a signal being sent by the device to the microprocessor when a magnetic field is sensed; and

an indicator which indicates the presence or the absence of a magnetic field, wherein the power source supplies current to the indicator, and the indicator turns on when a magnetic field is sensed and turns off when a magnetic field is not sensed; and

wherein the indicator is initially operable following the power source being inserted into the housing and the magnetic field sensor being powered up, and the microprocessor renders the indicator inoperable a predetermined period of time after the lid of the housing is closed following the power source being inserted into the housing and the magnetic field sensor being powered up, and the indicator remaining inoperable until the lid of the housing is removed and the lid of the housing is closed again at which point the indicator is operable until the microprocessor again renders the indicator inoperable a predetermined period of time after the lid of the housing is closed again.

10. A security alarm system having a proximity sensor, the proximity sensor including a magnet which generates a magnetic field and a magnetic field sensor, the magnetic field sensor comprising:

a housing having a lid;

a tamper switch which detects when the lid of the housing is opened;

a device which senses a presence or an absence of a magnetic field;

a power source, the magnetic field sensor being powered up when the lid of the housing is removed and the power source is inserted into the housing;

a microprocessor, a signal being sent by the tamper switch to the microprocessor when the lid of the housing is open, and a signal being sent by the device to the microprocessor when a magnetic field is sensed; and

an indicator which indicates the presence or the absence of a magnetic field, wherein the power source supplies current to the indicator, and the indicator turns on when a magnetic field is sensed and turns off when a magnetic field is not sensed; and

wherein the indicator is initially operable following the power source being inserted into the housing and the magnetic field sensor being powered up, and the microprocessor renders the indicator inoperable a predetermined period of time after the lid of the housing is closed following the power source being inserted into the housing and the magnetic field sensor being powered up, and the indicator remaining inoperable until the lid of the housing is removed and the lid of the housing is closed again at which point the indicator is operable until the microprocessor again renders the indicator inoperable a predetermined period of time after the lid of the housing is closed again.