Imphy S.a.

Metalimphy

Metalimphy & B.v.s.

La Societe Metalimphy

Pierre Lagarde

Gaston Denoor

Andre Elie

A method of marking and of identifying objects (1) which are non-conductors of electricity by inclusion of conducting masses and detection by passage through a high-frequency electromagnetic field and detection of the variation in the corresponding response signal picked up. Metallic wires (2) each selected from a range of specimens of different electric conductivity are used as marking elements. The responses are measured which are each characteristic of one specimen and of a predetermined code value. The invention applies to the recognition of the authenticity of cards or documents thus previously marked.

Method of marking and of identifying objects marked by electrically

In the identification of an article provided with at least one identifying magnetic member, each identifying member is selected from one or more production batches each of which has a characteristic hysteresis loop which is virtually non-reproducible. The member is subjected to analysis of its magnetic characteristics which are compared with those of a reference magnetic means comprising the same number of magnetic members from the same batches as the identifying magnetic members. Identical characteristics provide a correct identification. The detection apparatus may comprise two exciter coils for providing two alternating magnetic fields and two detector coils for each field connected in opposition. When an identifying magnetic member inserted in one field is identical to the reference magnetic member inserted in the other field, detection signals from the two detector coils cancel each other out.

Method of identifying articles

An apparatus and process for identifying objects marked by a magnetic band or thin filament comprising detecting the passage of the magnetic band in a detection zone comprising a framework having an excitation coil fed with alternating current to produce an alternating magnetic field and a detecting coil balanced with the excitation coil such that no signal normally will appear in the absence of a magnetic body in proximity to the framework. The passage of an object carrying a magnetic band in proximity to the framework producing for each alternation of the excitation field an unbalance in a detecting circuit and the appearance of a signal which is fed to apparatus for the detection and measurement of the phase of the signal with respect to the excitation field. The magnetic band is selectively divided at variable predetermined locations by cuts of variable predetermined extent such that at the time of passage of the bands proximate the detection zone, signals of variable amplitudes are also produced, the decoding of the signals being effected in the detection apparatus by measurement of their amplitude.

Process and apparatus for identification of objects

A conduit for conveyance of hot fluids includes an inner tube, through which the fluid passes, made of a material having a low coefficient of thermal expansion, preferably less than 5 .times. 10.sup.-6 per .degree. C and advantageously INVAR .RTM. with a coefficient of 2.3 .times. 10.sup.-6 /.degree. C. The inner tube is anchored at its ends and has no expansion-compensating means in its length is surrounded by a binding wrapping of a material having a coefficient of thermal expansion greater than that of the inner tube, prestressed at the temperature of application to compensate for the relaxation of stress in the wrapping due to the different expansions of inner tube and wrapping, and so as to compensate at least in part for changes in stress on the inner tube resulting from the absence of expansion-compensating means. A longitudinal tensile pre-stress may also be applied. The assembly also includes thermal insulation, disposed either outside the wrapping or between the wrapping and the inner tube. An outer protective coating may constitute the binding wrapping.

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Versailles, France

Pierre Lagarde