Electricity: measuring and testing – Magnetic – Magnetometers
Reexamination Certificate
2000-11-13
2004-06-15
Snow, Walter E. (Department: 2862)
Electricity: measuring and testing
Magnetic
Magnetometers
C324S258000
Reexamination Certificate
active
06750648
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a magnetic field sensor, and more particularly to a magnetic field sensor suitable for sensing a magnetic field generated by an objective one of interconnections formed at a high density without receiving any substantive influence of a magnetic field generated by an adjacent interconnection positioned very close to the objective interconnection.
Various types of the magnetic field detectors have been proposed to measure the magnetic field generated by the interconnection on the printed circuit boards. A semi-rigid coaxial line shielded loop magnetic field detector is disclosed in “IEEE Transactions on Antenna and Propagation” vol. AP-21, No. 4, pp. 446-461, July 1973. This semi-rigid coaxial line shielded loop magnetic field detector is illustrated in FIG.
1
. This semi-rigid coaxial line shielded loop magnetic field detector comprises a coaxial line in the form of a circular-shaped loop. The right half of the semi-rigid coaxial line shielded loop magnetic field detector comprises a coaxial line
51
which is half-circular shaped, wherein an end of the coaxial line
51
is positioned at the bottom of the circular-shaped loop, where a center conductive line
53
is striped thereby to form a gap
14
at the bottom of the circular-shaped loop. The left half of the semi-rigid coaxial line shielded loop magnetic field detector comprises a conductive line
52
which provides an electrical connection between the center conductive line
53
to an external line.
In measurement of the magnetic field generated by the objective interconnection
54
, the semi-rigid coaxial line shielded loop magnetic field detector is positioned just over the objective interconnection
54
so that the circular-shaped dielectric looped face is in parallel to the objective interconnection
54
, whereby magnetic flux generated by the objective interconnection
54
penetrates the circular-shaped dielectric looped face. As a result, a voltage output signal can be obtained from the semi-rigid coaxial line shielded loop magnetic field detector.
Another type of the magnetic field detector is disclosed in “IEEE Transactions on Magnetics” vol. 32, No. 5, pp. 4941-4943, September 1996.
The first conventional detector is unsuitable for selectively detecting a magnetic field generated by an objective interconnection
54
only without receiving any substantive influence of a magnetic field generated by an adjacent interconnection
55
positioned very close to the objective interconnection
54
as illustrated in FIG.
2
. The dielectric looped face of the detector receives the superimposed magnetic fields of the objective and adjacent interconnections
54
and
55
.
In order to solve the above problem, it is required to approach the loop center of the detector as close to the objective interconnection
54
as possible. A pitch of the adjacent two of the interconnections on the printed circuit board is very narrow, for example, 0.1 millimeter order. Notwithstanding, the first conventional semi-rigid coaxial line shielded loop magnetic field detector is hared to be scaled down due to difficulty in keeping a mechanical strength of the loop and not so small diameter of coaxial line of about 1 millimeter. The first conventional semi-rigid coaxial line shielded loop magnetic field detector is hand-made. This further makes it difficult to scale down of the detector.
In the meantime, the second conventional sensor comprises a planer circuit which is relatively suitable for scaling down the detector. Notwithstanding, the second conventional sensor is hard to be connected directly to a measuring apparatus without using a jig. The use of the jig for connecting the external coaxial line to the sensor makes it inconvenient to position the loop center as close to the objective interconnection as required to selectively detect the magnetic field of the objective interconnection only without receiving any influence due to the disturbing magnetic field generated by the adjacent interconnection.
In the above circumstances, it had been required to develop a novel magnetic field detector free from the above problems.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a novel device for detecting a magnetic field free from the above problems.
It is a further object of the present invention to provide a novel device for detecting a magnetic field, which is largely scaled down to enable a dielectric looped face to be positioned adjacent to an objective source of generating a magnetic field to be detected.
It is a still further object of the present invention to provide a novel device for detecting only a magnetic field generated by an objective magnetic field generating source.
It is yet a further object of the present invention to provide a novel device for detecting a magnetic field which is highly sensitive.
It is a further more object of the present invention to provide a novel device for detecting a magnetic field which is capable of electrically and mechanically secure connection to an external coaxial line.
The present invention provides a device for detecting a magnetic field comprising: a dielectric body; an electrically conductive pattern; and an electrically conductive ground region. The electrically conductive pattern so extends in the dielectric body as to form a dielectric looped face at least partially surrounded by the electrically conductive pattern, and the electrically conductive pattern having a first end electrically connected to an external electrically conductive line and a second end. The electrically conductive ground region is formed in the dielectric body. The electrically conductive ground region is electrically connected to the second end of the electrically conductive pattern and is electrically isolated from other parts of the electrically conductive pattern than the second end, so that the electrically conductive ground region serves as a ground to the electrically conductive pattern.
The above and other objects, features and advantages of the present invention will be apparent from the following descriptions.
REFERENCES:
patent: 5821902 (1998-10-01), Keen
patent: 6320376 (2001-11-01), Tamaki et al.
patent: 62-184384 (1987-08-01), None
patent: 1-291182 (1989-11-01), None
patent: 5-37122 (1993-02-01), None
patent: 8-129058 (1996-05-01), None
patent: 8-248080 (1996-09-01), None
John Dyson, “Measurement of Near Fields of Antennas and Scatters”, IEEE Transactions on Antennas and Propagation, vol. AP-21, No. 4, Jul. 1973, pp. 446-460.
M. Yamaguchi et al., “A New Permeance Meter Based on Both Lumped Elements/Transmission Line Theories”, IEEE Transactions on Magnets, vol. 32, No. 5, Sep. 1996, pp. 4941-4943.
D. Kacprzak, “The Analysis of Eddy-Current Distribution and Sensing Voltage of Micro ECT Probe for Inspection of PCB”, pp. 59-64, MAG-98-115.
Masuda Norio
Tamaki Naoya
NEC Corporation
Snow Walter E.
Young & Thompson
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