Electricity: measuring and testing – Magnetic – Magnetometers
Reexamination Certificate
1999-08-02
2001-10-16
Metjahic, Safet (Department: 2862)
Electricity: measuring and testing
Magnetic
Magnetometers
C324S247000, C338S03200R
Reexamination Certificate
active
06304082
ABSTRACT:
FIELD OF THE INVENTION
The invention relates generally to magnetic field sensing devices, and more particularly to a multi-axis magnetic field sensing device and methods for fabricating the same.
BACKGROUND OF THE INVENTION
In the design and construction of printed circuit boards (PCBs), it is often desirable to sense and measure the intensity or direction (or both) of a magnetic field or of a component of a magnetic field in a particular direction. A device capable of sensing and measuring the magnetic field or a component of a magnetic field is a magnetometer. A magnetometer can be used to sense and measure the intensity of a component of a magnetic field along a particular dimension, such as the horizontal or vertical plane of a PCB. A horizontal-intensity magnetometer and a vertical-intensity magnetometer are typically used to sense and measure the magnetic field along the horizontal and vertical plane, respectively, of a PCB.
In the case where the PCB is flexible to allow positioning of the circuitry in a particularly shaped housing of an electronic device, it is preferred to use a magnetic field sensing device capable of sensing the magnetic field in more than one axis or dimension. Further, a magnetic field sensing device capable of sensing the magnetic field in more than one axis or dimension is also preferred when one or more additional PCBs, i.e., daughterboards, are electrically attached to a main PCB, i.e., motherboard, to allow increased functionality.
Attachment of daughterboards to motherboards is typically done using a connector so that the electrical configuration can be changed by replacing a daughterboard with another type. Permanent attachment of a daughterboard to a motherboard is sometimes desirable and this is generally achieved by conventional surface mount soldering techniques.
Accordingly, a need exists for a device capable of sensing and measuring a magnetic field along multiple axes. A need further exists for methods of fabricating the device capable of sensing and measuring the magnetic field along multiple axes.
SUMMARY OF THE INVENTION
The present invention provides a multi-axis magnetic field sensing device capable of sensing and measuring the magnetic field of a printed circuit board (PCB) in more than one dimension or axis and methods for fabricating the same. Preferably, the magnetic field sensing device of the present invention is assembled from individual magnetic field sensing circuit components which have a field sensitive axis in their mounting plane or along a particular plane.
According to the present invention, when sensing of only two orthogonal magnetic field components is desired, two such field sensing circuit components are mounted in an angular relationship to each other on the plane of a wiring board or PCB. When three orthogonal magnetic field components must be sensed or measured, at least one field sensing circuit component is mounted outside the plane of the other field sensing components. This is accomplished by first mounting the magnetic field sensing circuit component on a daughterboard, and then permanently attaching the daughterboard electrically and mechanically to a motherboard on which are mounted the other magnetic field sensing circuit components.
The multi-axis magnetometer of the present invention includes three magnetic field sensing circuits for sensing a magnetic field along the X, Y and Z axes. Each magnetic field sensing circuit includes an operational amplifier and a bridge chip having at least one electrical conductor. The operational amplifier is electrically connected to the at least one electrical conductor of the bridge chip for receiving a portion of a current flowing through the at least one electrical conductor. The operational amplifier provides an output voltage based on a magnitude of the portion of the current flowing through the at least one electrical conductor. The multi-axis magnetometer further includes a voltage regulator for providing an operating voltage.
A method is also provided for fabricating the multi-axis magnetometer which includes the steps of providing at least one bridge chip having at least one electrical conductor on a motherboard; providing at least one operational amplifier to the motherboard; electrically connecting the at least one electrical conductor to the at least one operational amplifier; providing at least one bridge chip having at least one electrical conductor on a daughterboard; providing at least one operational amplifier to the daughterboard; electrically connecting the at least one electrical conductor of the at least one bridge chip on the daughterboard to the at least one operational amplifier on the daughterboard; and attaching the daughterboard to the motherboard.
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patent: 4109199 (1978-08-01), Ball et al.
patent: 4742356 (1988-05-01), Kuipers
patent: 5110298 (1992-05-01), Dorinski et al.
patent: 5689185 (1997-11-01), Widdershoven et al.
patent: 5850624 (1998-12-01), Gard et al.
patent: 2276727 (1994-05-01), None
patent: WO 96 02847 (1996-02-01), None
Gualtieri Devlin M.
Kollmyer Robert E.
Honeywell International , Inc.
Metjahic Safet
Yeadon Loria B.
Zaveri Subhash
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