Electric heating – Metal heating – By arc
Patent
1989-07-26
1992-06-23
Albritton, C. L.
Electric heating
Metal heating
By arc
21912168, B23K 2600
Patent
active
051245230
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a process for frequency range tuning a resonant circuit of metal-plastic-metal laminate foil for an identification label or tag and a laminate foil suitable for carrying out the process.
Identification tags are employed with a single resonant circuit for example thief-proof labels, or a plurality of resonant circuits such as for example for arranging objects such as packets, cases or in certain countries in vehicles to calculate road user's taxes, in all cases for non-contact identification of objects that are not kept in a fixed place.
The production and use of the resonant circuit of metal-plastic-metal laminate foil for such identification labels or tags is in fact known from U.S. Pat. No. 3,671,721 and No. 86/02186. In order to employ resonant circuits as identification tag/tags it is necessary that each resonant circuit causes interference within an exactly prescribed frequency range of close tolerance and, consequently, for example when used as a tag to prevent theft, actuates an optical or accoustic signal.
A resonant circuit can be made from a metal-plastic-metal laminate foil which, from the choice of material is of high quality and can be manufactured in a continuous manner. Difficulties do arise in large scale or mass production of resonant circuit structures of metal-plastic-metal laminate foils as the production parameters and in particular the thickness tolerances of the layers of laminate foil used, as well as the alterations in the foil necessary in the construction of the individual resonant circuits, have a considerable influence on the detection frequency of the finished resonant circuit
SUMMARY OF THE INVENTION
The object of the invention is therefore to develop a suitable process by means of which it is possible, at high speed, semi-continuosly and fully automatically to tune the frequency of resonant circuits for identification tags made from rolls of laminate foil to a particular frequency range value and to develop a laminate foil suitable for carrying out the said process.
Metal-plastic-metal laminate foils are as such well known. The object of the invention in this respect lies in the choice of the individual components thereof.
With respect to the process the object of the invention is achieved in accordance with the present invention which comprises a process for frequency range tuning a resonant circuit of metal-plastic-metal laminate foil for an identification tag, in which in the case of resonant circuits having frequencies less than the intended frequency, made from laminate foil rolls or the like joined together by means of at least one common plastic foil and moved forward in an almost continuous manner, the actual frequency of a first resonant circuit is determined by a first frequency measurement cell and compared with the prescribed, intended frequency, the difference in frequency communicated to a correction unit which regulates a trimming unit that when the said first resonant circuit is fed to it is designed to correct the actual frequency of the first resonant circuit to the intended frequency by shortening i.e. trimming the condensor foil part remote from the spool part, after leading the first resonant circuit to a second frequency measurement cell the new actual frequency is determined whereupon, if this lies within the intended frequency range, the position of the trimming unit determined by the correction unit is taken as the basis for setting the trimming unit for a subsequent resonant circuit so that for the final positioning of the trimming unit to trim the next resonant circuit only small corrections are required or, if the new actual frequency lies outside the intended frequency range, this first resonant circuit is marked and for the tuning of a subsequent resonant circuit the measurement is started again using the prescribed, intended frequency.
In accordance with the present invention, the measurement cells may perform an oscillating frequency-range sensing operation. Further, not more than nine r
REFERENCES:
patent: 4381441 (1983-04-01), Desmarais et al.
Neuartige Verbundwerkstoffe aus Metall und Polyathylen, by Hofman, Kunstoffe, 1969, vol. 59, pp. 85-88.
Gedruckte Schaltungen Technologie der Folienatztechnik, By Eisler, 1961, pp. 40-51.
Bubeck Dietrich
Kolb Franz
Oehlmann Klaus
Werner Martin
Albritton C. L.
Swiss Aluminium Ltd.
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