Communications: electrical – Condition responsive indicating system – Specific condition
Reexamination Certificate
1999-09-30
2001-08-21
Trieu, Van T. (Department: 2736)
Communications: electrical
Condition responsive indicating system
Specific condition
C340S551000, C340S572600
Reexamination Certificate
active
06278368
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to systems and materials for presence sensing, and in particular, to a low cost material with magnetizable filaments whose presence may be sensed remotely by an industrial control system to communicate multiple bits of information.
In the manufacture of a multi-component product, for example, packaged pharmaceuticals intended for over-the-counter sale, it is important to verify that the package includes a paper insert listing the characteristics of the drug and instructions for safe use. While considerable care is taken in placing the insert into the package, ideally, its presence in the package could be verified after the package is sealed. One way of doing this is by weighing the package to detect the additional weight of the insert. For light inserts or products that vary in weight, such an approach is unreliable.
The parent to the present application describes a method of verifying the presence of a component of a manufactured product by incorporating a small percentage of filamentized magnetic material into that component whose presence may be detectable at a distance. The filaments are of low cost and may be freely dispersed into the material of the component for manufacturing convenience and may be remotely sensed even through packaging or the like.
While the ability to sense an individual component in a manufactured product is valuable, often it may be necessary to sense combinations of components or to distinguish between different component types. It would be desirable to have a method of communicating not simply presence or absence of a component representing a single binary “bit” of information, but to be able to detect combinations of components and to distinguish between different components such as requires the communication of multiple bits of information.
BRIEF SUMMARY OF THE INVENTION
The present inventors have recognized that low cost magnetizable filaments similar to those described above may be used to convey, not merely a “presence” or “absence” signal, but multiple bits of information. In particular by using magnetic materials having different coercivities, distortions in an externally imposed periodic magnetic waveform will be displaced in phase for the different magnetic materials allowing independent detection of each material. The presence or absence of each material provides one bit of information in a multi-bit word. The length of the multi-bit word is determined by how many different materials are used.
Specifically, the present invention provides a marker material suitable for remote sensing of multi-bit information including a non-magnetic matrix and at least a first and second set of magnetic filaments supported and dispersed by the matrix. Each set of magnetizable filaments has a first functional relationship between magnetic induction (B) and magnetic field (H) that differs from the others.
Thus, it is one object of the invention to provide an easily manufactured and low cost material for conveying multiple bits of information to a remote sensor. The filaments are relatively inexpensive and their orientation need not be precisely controlled, therefore they may be easily incorporated into a variety of materials.
The proportion of the filaments of the first and second filament sets may be a predetermined unequal proportion based to their detectability by a remote sensor.
Thus it is another object of the invention to provide flexibility in selecting the magnetic material allowing the use of materials with different coercivity and low permeability while ensuring adequate signal levels.
The present invention also provides for a sensing apparatus for the material containing the multiple sets of magnetizable filaments. Specifically, the sensor includes an electric oscillator producing a waveform having a fundamental frequency and an antenna structure connected to the electric oscillator for transmitting the waveform as an electromagnetic field to envelop the sets of magnetizable filaments. A receiver, connected to the antenna structure, receives the electromagnetic field as modified by the sets of magnetizable filaments and a detector discriminates between their magnetic properties to independently detect the individual sets of magnetizable filaments.
Thus, it is another object of the invention to provide a simple method of remotely detecting the multi-bit information.
The detector may be a differentiator (as is implicit in a coil detector) and a phase sensitive threshold detector detecting peaks in the derivative of the received electromagnetic field as a function of the phase of the waveform of the electric oscillator.
Thus, it is another object of the invention to exploit the effect of the magnetizable filaments in causing distortions of an applied magnetic field such as changes the instantaneous slope with respect to time of the electromagnetic field.
Alternatively or in addition, the remote sensing system may include a Fourier transformer and a threshold detector for detecting magnitudes of Fourier components at predetermined harmonics of the waveform of the electric oscillator.
Thus, it is another object of the invention to provide a method for more generally detecting distortion of the applied electromagnetic field.
The present invention may be used in verifying manufacturing operations in the assembly of multi-component products or the like. In this application, a first and second component of the multi-component product are identified and magnetizable filaments having different magnetic properties are attached respectively to the first and second components. The assembled multi-component product is then exposed to an electromagnetic waveform and the distortion of the waveform caused by different magnetic induction in the magnetizable filaments is detected to detect the presence of the first and second components. An output signal is provided indicating proper assembly of the multi-component product.
The output signal may indicate that none or both sets of magnetizable filaments for the first and second components have been detected or that a specific one and only one of the sets of magnetizable filaments have been detected.
Thus, it is another object of the invention to provide a method not only of ensuring proper assembly of multiple component devices requiring both a first and second component or in distinguishing between different versions of a multi-component product having, in the alternative, the first or second components. Numbers may be encoded in binary format according to the presence or absence of the detected sets.
The foregoing and other objects and advantages of the invention will appear from the following description. In the description, reference is made to the accompanying drawings which form a part hereof and in which there is shown by way of illustration a preferred embodiment of the invention. Such embodiment does not necessary represent the full scope of the invention, however, and reference must be made to the claims herein for interpreting the scope of the invention.
REFERENCES:
patent: 4215342 (1980-07-01), Horowitz
patent: 4915728 (1990-04-01), Schell
patent: 5576693 (1996-11-01), Tyren et al.
patent: 5664582 (1997-09-01), Szymaitis
patent: 5834748 (1998-11-01), Litman
patent: 5988500 (1999-11-01), Litman
patent: 6053406 (2000-04-01), Litman
Engdahl Jonathan R.
Fooks Elik I.
Goldberg Ira B.
Hollingsworth Charles S.
McKinney Ted M.
Baxter Keith M.
Horn John J.
Rockwell Technologies LLC
Trieu Van T.
Walbrun William R.
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