US 6,191,698 B1 · Magnetic testing apparatus

Abstract

An apparatus for testing whether the strength of a stray magnetic field emanating from an air freight consignment exceeds a predetermined threshold value has a magnetic field sensor, as a Hall probe, further an optical and/or acoustical alarm device, an electronic circuit coupling the sensor to the alarm device and actuating the alarm device(s) to produce a pre-warning signal, when the strength of the magnetic field sensed exceeds half the threshold value, and a warning signal when the strength of the magnetic field sensed by the sensor exceeds the predetermined threshold value, a nonmagnetic distance determining device, which, when brought in contact with a point on the surface of the consignment establishes a predetermined distance between the contacted surface point and the sensor; and means for self-testing the function of the apparatus.

Claims11

Dependent claims

An apparatus for testing whether the strength of a stray magnetic field emanating from a package to be investigated exceeds a predetermined value (threshold value) at a given distance from a surface of said package, said apparatus comprising:

a magnetic field sensor producing an electric output signal that is a function of the magnetic field sensed;
indicating means producing a signal indicating that the threshold value is exceeded;
circuit means having an input coupled to said sensor and an output coupled to said indicating means to actuate said indicating means when said threshold value is exceeded;
nonmagnetic distance defining means which when contacting selected point on a surface of said package establishes a predetermined distance between said point and said sensor.

1 more element

Dependencies are inferred from the claim text.

Magnetic testing apparatus

Life of this patent

Magnetic testing apparatus

Life of this patent

Abstract

Claims11