Electricity: measuring and testing – Magnetic – With means to create magnetic field to test material
Reexamination Certificate
2002-01-31
2003-10-28
Snow, Walter E. (Department: 2862)
Electricity: measuring and testing
Magnetic
With means to create magnetic field to test material
C324S209000, C324S232000, C073S779000, C436S149000, C374S163000
Reexamination Certificate
active
06639402
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
In general, the present invention relates to temperature, stress, and chemical telemetry using sensing elements remotely located from associated electromagnetic (EM) emission pick-up and processing units that, in operation, detect emissions from the element. The invention targets temperature sensing, sensing and characterization of localized stress conditions of a solid analyte, and the monitoring one or more corrosive. More particularly, the invention is directed to a novel telemetering apparatus that employs a receiver to measure the intensity of electromagnetic emissions from a magnetically soft sensor element, whereby there is no hardwire connection between the receiver and the sensing element, and the receiver ‘listens’ for harmonics of the fundamental resonant frequency in order to carry out the temperature, stress, and corrosive monitoring telemetry. The invention is further directed to new telemetry techniques associated with the sensing apparatus of the invention, including: sensing temperature, determining stress conditions of a solid undergoing analysis, and sensing the presence or absence of, type, concentration of, or degradation caused over time by, one or more corrosive (such as chlorine) in a wide variety of environments. For example, the new apparatus provides a way to measure temperature, stress conditions, and corrosives, including: (a) sensing material degradation or localized permanent deformation (of single materials, composites, or laminates) caused by corrosion, temperature fluctuation, weather conditions, etc., thus, allowing for the identification of regions of actual or potential material fatigue and failure; (b) sensing internal or surface stress due to applied loads such as are experienced by construction materials (building or roadway), including repeated or prolonged exposure to a load, explosion, wind and weather conditions; (c) sensing temperature or corrosive concentration and/or type within a test sample or product packaging (during quality inspections/audit); and so on.
The new sensing element structures and technique provide information about a solid analyte or an environment utilizing the harmonic response of EM emissions of one or more sensor structures made of a magnetically soft sensing element. Furthermore, a magnetically hard (MH) element supporting a biasing field adjacent the magnetically soft sensing element can be included to provide additional functionalities, including: EM background noise; element ON-OFF switch; and biasing field response, where needed, by selective response of the MH element upon exposure to chemical species.
General Technical Background Discussion—Other Telemetry Devices
As is generally well known, electric and magnetic fields are fundamentally fields of force that originate from electric charges. Whether a force field may be termed electric, magnetic, or electromagnetic hinges on the motional state of the electric charges relative to the point at which field observations are made. Electric charges at rest relative to an observation point give rise to an electrostatic (time-independent) field there. The relative motion of the charges provides an additional force field called magnetic. That added field is magnetostatic if the charges are moving at constant to velocities relative to the observation point. Accelerated motions, on the other hand, produce both time-varying electric and magnetic fields termed electromagnetic fields. For general reference see the textbook,
Engineering Electromagnetic Fields and Waves
, Carl T. A. Johnk, John Wiley & Sons, 2
nd
Edition (1988).
Anti-theft markers/tags (electronic article surveillance, EAS, markers) generally operate by “listening” for acoustic energy emitted in response to an interrogating AC magnetic field, to sense the presence of an EAS marker. Sensormatic, Inc. distributes an EAS tag (dimensions 3.8 cm×1.25 cm×0.04 mm) designed to operate at a fixed frequency of 58 kHz (well beyond the audible range of human hearing). These EAS tags are embedded/incorporated into articles for retail sale. Upon exiting a store, a customer walks through a pair of field coils emitting a 58 kHz magnetic field. If a tag is still in an article being carried by the customer, the tag will likewise emit a 58 kHz electromagnetic signal that can be detected using a pickup coil, which in turn may set off an audible or visual alarm. More-recently, these tags are being placed in a box-resonator, sized slightly larger than the tag, such as the tags placed within a cavity 20 of a housing (see
FIG. 2
of Winkler et al.).
Winkler et al. describes an electronic article surveillance (EAS) anti-theft system that operates by detecting mechanical resonances of magnetostrictive elements made of amorphous metallic glass METGLAS® 2826 MB, to prevent or deter theft of merchandise from retail establishments. In response to an interrogation signal generated by energizing circuit
201
, the interrogating coil
206
generates an interrogating magnetic field, which in turn excites the integrated marker portion
12
of the article of merchandise
10
into mechanical resonance. During the period that the circuit
202
is activated, and if an active marker is present in the interrogating magnetic field, such marker will generate in the receiver coil
207
a signal at the frequency of mechanical resonance of the marker. This signal is sensed by a receiver which responds to the sensed signal by generating a signal to an indicator to generate an alarm.
Anderson, III et al. discloses a marker
16
(
FIG. 5
) formed of a strip
18
of a magnetostrictive, ferromagnetic material adapted, when armed in its activated mode, to resonate mechanically at a frequency within the range of the incident magnetic field. A hard ferromagnetic element
44
disposed adjacent to the strip
18
is adapted, upon being magnetized, to magnetically bias the strip
18
and thereby arm it to resonate at that frequency. An oscillator provides an AC magnetic field within interrogation zone
12
to mechanically resonate a magnetostrictive strip
18
, which has first been armed by a magnetized hard ferromagnetic element
44
, upon exposure to this AC magnetic field. The sole object of Anderson, III et al. EAS marker is to detect the presence between coil units
22
and
24
(interrogation zone
12
) of an “armed/activated” marker
16
. In the event an activated marker
16
secured to a retail article is detected within zone
12
, an alarm will sound. A deactivator system
38
, electrically connected to a cash register, can be used to deactivate the marker.
Humphrey and, another reference, Humphrey et al. disclose a type of electronic article surveillance (EAS) marker which includes a thin strip or wire of magnetic material that, when exposed to an alternating interrogation signal of low frequency and low field strength, responds by generating a signal pulse that they state “causes a regenerative reversal of magnetic polarity generating a harmonically rich pulse that is readily detected and easily distinguished.” And while the Humphrey references recognize that high harmonics are detectable for the low frequency interrogation fields they use, once again, it is simply the presence or absence of the EAS marker that is of any interest.
Schrott, et al. describes a multibit bimorph magnetic ID tag for attachment to, and identification of, an object. The tag has one or more bimorphs comprised of a thin strip of a magnetostrictive material attached to a thicker bar
21
of hard magnetic material. A shipping pallet, package, or product is tagged with the bimorph for later product identification. Schrott et al. indicates that a multibit tag could be programmed to generate a binary or other suitable code. In the binary code case, a certain frequency of an array of cantilevers can be assigned a value of “zero” or “one” and, if absent, it can take the opposite value. The Schrott, et al. ID tag is limited to coded (zeros and ones) identification of the object. If, in operation, a Schrott, et al. I
Grimes Craig A.
Ong Keat Ghee
Macheldt Bales LLP
Snow Walter E.
University of Kentucky Research Foundation
LandOfFree
Temperature, stress, and corrosive sensing apparatus... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Temperature, stress, and corrosive sensing apparatus..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Temperature, stress, and corrosive sensing apparatus... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3118873