FR2607937A1 - METAL DETECTOR - Google Patents

Abstract

THE PRESENT INVENTION RELATES TO A METAL DETECTOR. THIS METAL DETECTOR INCLUDES AN EXTENDED SUPPORT 1, WHICH IS MADE OF AN INSULATING MATERIAL AND IS EQUIPPED WITH A PLURALITY OF ELECTRIC WINDINGS 2, 3, WHICH ARE PHASES AND WINDINGS IN COAXIAL PROPELLERS AROUND SAID SUPPORT; THIS SUPPORT ALSO CONTAINS A MEANS OF PROTECTION AND DRESSING.

Description

The present invention relates to a metal detector and more

  particularly to a detector equipped with an elongated support provided with a plurality of windings, superimposed or not, arranged along its entire length or a portion thereof and wound coaxially. It is an element intended to be used as transmitter and / or receiver in the realization of such metal detectors, and more particularly weapons, in positions

control.

  Currently, metal detectors are known

  comprising transmitter and receiver devices constituting

  killed by flat electrical windings, housed between panels arranged opposite each other in an area

appropriate checkpoint.

  Despite the measures adopted, at the level of

  brication, to make them sensitive also to metal masses of small dimensions, the aforementioned devices

  require the use of coils of relative dimensions-

  important, and therefore of panels (between which they are housed) having a relatively large length, which limits their use mainly to

appropriate length control.

  Such a disadvantage has been eliminated by a detection

  elongated support metal (object of Italian Patent N 190 960 filed April 30, 1982 by the Applicant of the

  present invention), which comprises an elongated support

  circular arrangement for a winding which is arranged between

  the ends of it and is wound helically

  how one obtains a succession of polarities elec-

  alternating tromagnets arranged along the same gen-

  of the cylindrical support and this to cancel the effects

  external electromagnetic field.

  The metal detector of the type just described, however, has certain disadvantages that the

  The present invention aims to eliminate.

  This is the non-uniform distribution of the electromagnetic field produced by the elongated support detector, when it is used as an emitter, as well as the presence of a helical profile surface which is defined around the elongated support and which separates electromagnetic fields with a different orientation and

  minimum values at this surface.

  Because of the existence of this surface, parasitic currents of minimal intensity would be induced in a flat metallic body moving along this surface, the low value of these parasitic currents being responsible for the fact that the device in question is

  not sensitive to the corresponding variations in the elec-

  tromagnetic, and this in the reception phase: the re-

  sultat is that the presence of such a flat metal body

can not be detected.

  In addition, since around the support

  length is wound a single winding, between the ends

  of this medium, the detector can not indicate the

  level at which a disturbance of the elec-

  tromagnetic, so that it can not

  distinguish disturbance agents from the electron field

  at different heights relative to the base and / or the top of the elongate support: the result is that the disturbance agents in question may be ignored (undetected) in a control station

  in which the detector is arranged.

  The subject of the present invention is a metal detector comprising an elongate support on which two or more windings are arranged that are out of phase with each other and wound helically around said support.

  in the same direction or in the opposite direction. If the rolls

  are wound in the same direction, the helical surfaces

  coaxial co-axial with the above-mentioned elongated support, at which the electromagnetic field is minimal

  are distinct and parallel to each other.

  If, on the other hand, the windings are

  In opposite directions, there is a line common to each turn of the windings. Similarly, we obtain surfaces and lines of intersection (between these

  faces) when using a higher number of windings

two to one.

  The elongate support according to the invention, thus equipped, can be used as a transmitting device comprising a number of separate emitter and / or receiver windings. A similar situation exists for the elongated support equipped as specified above,

  when used as a receiver device.

  This being so, a metal body moving along one of the aforementioned helical surfaces, at the level of

  which the electromagnetic field is minimal is

  would see on a surface at which the electromagnetic field is isolated for the other (or the others)

  winding (s), which makes the metal body detectable.

  Similarly, if the surfaces at which the

  electromagnetic field is minimal intersect, one obtains

  minimal (and thus undetectable) disturbances only in the vicinity and on the line of intersection, but

  not on both sides of this line.

  When asked to distinguish between objects

  at different heights with respect to the base and / or the top of the elongate support, and therefore in the control station, this support may consist of several superimposable sections, each of which is equipped with one or more helical windings intended for be connected to one or more appropriate circuits of

Signal processing.

  In addition to the foregoing, the invention

  other provisions, which emerged from the

  will be described in the following description.

  The invention will be better understood by means of

  additional description which will follow, which refers

in the appended drawing in which:

  Figure 1 is a perspective view of a sup-

  elongated port on which two windings are arranged

  substantially perpendicular to each other, wound in

lice in the same direction.

  Figure 2 is a perspective view of a sup-

  elongated port on which two windings are arranged

  substantially perpendicular to each other, wound in

in opposite directions.

  Figure 3 illustrates a support with three sections each of which is intended to be equipped with a winding

in helix.

  Figure 4 shows a mode of realization of

  connections between adjacent sections of the support and a

  tubular support able to reinforce this support and to protect

  windings against mechanical stresses ex-

dull.

  It must be understood, however, that this

  sin and the corresponding descriptive parts, are given solely by way of illustration of the object of the invention

  which they do not constitute in any way a limitation.

  In the drawings, numeral 1 refers to an elongate tubular support, which can be

  hollow inside, with a circular section, polygo-

  nal or other and, in any case, made of insulating material * and non-ferromagnetic, so as not to

  alter the distributions of the electromagnetic field -

  which is created in the space around it - and not to give rise to energy losses. The frequency of the electromagnetic fields concerned is variable, even if

  impulsive, depending on the applications.

  On the outer surface of the elongated support 1

  incisions or grooves of guiding

  and positioning of the windings which are described below. Numerals 2 and 3 refer to two windings which are spaced apart angularly and are wound around the elongate support 1 so as to generate, according to a generatrix of the elongated support, a

  succession of electromagnetic polarities of

  posed, and in particular having an equal number of polarities

opposite signs.

  Windings 2 and 3 can also be inte-

  by shorter turns intended to be distributed

  fogging towards the base and / or the upper end of the support 1, in order to make the effects more uniform over the entire length of the support 1 itself. Similarly, it is also possible to adapt screen conductors, one end of which is connected to ground to reduce the influence of possible

electrostatic effects.

  Reference numeral 4 refers to sec-

  tions of which the elongate support 1 may be composed and whose number is at least equal to 2. The connection between the

  component sections 4 can be made by interlocking,

  particularly by providing in the thickness of the wall

  superposed, and parallel to the common axis, orifices 6 intended to receive assembly pins 5

  protruding from either side of a spreading element

  in the form of a wafer or pellet, now

  consecutive sections and thus enabling

  on the upper end of the lower section

  above and at the lower end of the upper section

  upper (of said two consecutive sections superimposed)

  wires of which the windings are composed.

  Reference 7 relates to the insulating jacket intended to protect the windings 2 and 3 and to ensure the mechanical stability of the support 1, when

  is made in two or more sections.

  In an advantageous embodiment, the

  port 1 and the sheath 7 can be made in one piece, the windings being embedded in the single piece

thus achieved.

  As is apparent from the foregoing, the

  tion is not limited to those of its modes of

  implementation and application that have been described more explicitly; on the contrary, it embraces all the variants that may come to the mind of the technician in the field, without departing from the frame or the scope,

of the present invention.

Claims (9)

  1.- Metal detector comprising an elongate support, characterized in that this support (1) is realized   made of an insulating material and is equipped with a plurality of   electric bearings (2,3), which windings are   out of phase and wound in coaxial helices around said   port, and in that this support comprises means (7) for pro- tection and dressing.   2. Detector according to claim 1, characterized   characterized in that the elongated insulating support (1) has a   or more sections (4) superimposed.   3. Detector according to any one of the   1 or 2, characterized in that said support comprises   te grooves on its surface facilitating the establishment said windings.   4. Detector according to any one of the   1, 2 or 3, characterized in that said means for pro-   tection and dressing of said elongated support, equipped with these   windings, is constituted by an insulating jacket (7).   5. Detector according to any one of the   2 or 3, characterized in that said elongated support   (1) and its protective and dressing jacket (7) are   in one piece, said windings being embedded in   the unique piece of which the support / shirt association is composed.   6. Detector according to claim 1, characterized   characterized in that it comprises at least two non-superposed windings, so as to create electromagnetic fields having different distributions in the space surrounding the elongate support, when they are traversed by currents parasites.   7. Detector according to claim 1, characterized   characterized in that said windings are helically wound   in the same direction around the elongated support (1).   8.Detector according to claim 1, characterized   in that said windings are arranged in a helix   and in opposite directions around said elongate support (1).   9. Detector according to claim 1, characterized   characterized in that said windings each comprise turns closer to the ends of said support   length or each of the sections of which it is composed.