Apparatus and method of increasing the sensitivity of magnetic sensors used in magnetic field transmission and detection systems
First Claim
1. A magnetic sensor for use an inductively coupled magnetic field transmission and detection system comprising:
- (a) a magnetic core having a proximal end and a distal end;
(b) a conductive wire wrapped around said magnetic core thereby forming a coil around said magnetic core;
(c) a first magnetic flux concentrator magnetically coupled to the magnetic core at its proximal end; and
(d) a second magnetic flux concentrator magnetically coupled to the magnetic core at its distal end.
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Accused Products
Abstract
The present invention is directed to an apparatus and method of increasing the sensitivity of a magnetic sensor embedded in a key fob used in passive keyless entry and identification systems. The sensitivity of the sensor is increased by magnetically coupling a pair of magnetic flux concentrators at opposite ends of the magnetic core of the sensor, which is surrounded by a helical conductive coil. Addition of the magnetic flux concentrators external to the coil effectively forces a larger window of magnetic flux through the coil than was possible without them. This increases the magnetic sensitivity of the coil as a sensor in a time varying magnetic field. In a key fob/passive keyless device this results in an increased range of operation.
5 Citations
29 Claims
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1. A magnetic sensor for use an inductively coupled magnetic field transmission and detection system comprising:
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(a) a magnetic core having a proximal end and a distal end;
(b) a conductive wire wrapped around said magnetic core thereby forming a coil around said magnetic core;
(c) a first magnetic flux concentrator magnetically coupled to the magnetic core at its proximal end; and
(d) a second magnetic flux concentrator magnetically coupled to the magnetic core at its distal end. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An inductively coupled magnetic field transmission and detection system comprising:
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(a) a transmitter having an inductor that generates a time varying magnetic field; and
(b) a receiver inductively coupled to the transmitter, which has a magnetic sensor that senses the presence of the magnetic field, said magnetic sensor comprising;
(i) a magnetic core having a proximal end and a distal end;
(ii) a conductive wire wrapped around said magnetic core thereby forming a coil around said magnetic core;
(iii) a first magnetic flux concentrator magnetically coupled to the magnetic core member at its proximal end; and
(iv) a second magnetic flux concentrator magnetically coupled to the magnetic core at its distal end. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. A method of increasing the sensitivity of a magnetic sensor having a magnetic core, which has a proximal end and a distal end, comprising the steps of:
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(a) magnetically coupling a first magnetic concentrator to the proximal end of the magnetic core; and
(b) magnetically coupling a second magnetic concentrator to the distal end of the magnetic core. - View Dependent Claims (26, 27, 28, 29)
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Specification