EFECTO BARKHAUSEN PDF

En el presente trabajo se desarrolla, a partir del efecto Barkhausen, voltaje inducido en la bobina, conocido como ruido magnético Barkhausen (RMB), con el. Keywords: Magnetic Barkhausen noise, carbon steel welding, non-destructive magnetic testing, signal .. “Utilización del efecto Barkhausen. Mathematical model to characterize the ageing on over aged 12Cr1MoV steel starting from Barkhausen effect. Ingeniería Mecánica [online]. , vol, n.1, pp.

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Security element for electronic article surveillance. The invention relates to a security element for electronic article. The security elements in the form of soft magnetic material strips are widely used in department stores for the protection of goods against theft.

To achieve a sufficiently high rate detection procedures subtly designed which effectively reduce the risk of false alarms are used. This has been disclosed, in EP B broadcast the interrogation zone, in addition to two interrogation fields with the frequencies f1 and f2 in the band of kHz, a field with a frequency so located in the band of Hz. The interrogation field low frequency results in that the security element is carried, the rate of this field from saturation in one direction to saturation in the other direction.

The characteristic signal therefore appears periodically with the frequency of the low frequency field. Alternatively a detection system so called harmonic solution has been given only also discloses the use an interrogation field, located in the band of kHz for excitation of the security element, wherein the characteristic signal of the security element it appears again with the rhythm of a low frequency field, carrying the magnetically soft material and forth between the two saturations.

For evaluation then compares the shape of the characteristic signal with a predetermined signal form. Hysteresis curves of security elements are made of a soft magnetic material present between the two states of saturation, a substantially linear path. They have also been disclosed security elements whose hysteresis curves show a continuous transition between the two states of saturation, as soon as they are forced by an external magnetic field, to change its direction of saturation.

Materials with inconstant transition behavior between the two saturation states are designated as “materials Barkhausen effect”. And in the band of low frequencies they have a high permeability, meaning that they are excited by interrogation fields of low frequency, for outputting a signal characteristic.

Furthermore, the signals characteristics of the Barkhausen material is distinguished by a sharp peak. This means again that in the higher order harmonics still a relatively large signal component appears. Such materials are manufactured by suitable heat treatment of soft magnetic materials. In US-PS 4,, or also in EP A1are explained in detail the properties of these materials as well as the physical basis of Barkhausen effect.

Julio Capó Sánchez – Referințe bibliografice Google Academic

Publications cited in the prior art referred to in particular by special physical treatment of magnetically soft material, it can be converted into a material with a high Barkhausen effect. The security elements which use the Barkhausen effect differ markedly with respect to their way of signal elements soft magnetic security. The situation is different when you want to get a security element is recognized both by a harmonic surveillance system as one Barkhausen.

The invention the problem of proposing a security element that is detected by surveillance systems operating in different frequency bands arises. El problema se resuelve mediante el siguiente perfeccionamiento: By suitable choice of the magnetic properties of these lateral sections saturation magnetization, demagnetization factor, privileged direction help reduce the effective demagnetizing factor of the security element.

Thereby magnetisability the security barkhausenn in the interrogation field is facilitated, since the Barkhausen effect material then has a highly elevated rectangular loop efecti small field strengths saturation.

Another optimization can be achieved by a suitable relative arrangement to each other two materials, ie the material Barkhausen effect of the magnetically soft and amorphous fibers.

File:Barkhausensprung.gif

This can minimize coupling of both materials through their magnetic fields. The simplest case would naturally choose correspondingly large separation between the security element and Barkhausen feecto soft fibers.

Esto trae, sin embargo, la desventaja de que el elemento de seguridad combinado debe ser dimensionado grande lo que en general se desea evitar por motivos de costes. This brings, however, the disadvantage that the combined security element should be sized large which generally is to be avoided for cost reasons.

Optimization in the sense of the invention means rather find a compromise between minimal interaction of materials and detection rate as high as possible in systems which are structured to signal detection characteristics in different frequency bands. According to an advantageous embodiment of the security element according to the invention, it is proposed that the material with Barkhausen effect, as strips or wires, is oriented parallel to the fibers of the soft magnetic material.

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To this magnetically soft fibers are oriented, in the wet state by the action of external force, essentially in a preferred direction. This is achieved, for example, thanks to the magnetically soft fibers are subjected to a magnetic field, the still wet dope state. If the size of the security plays a subordinate role is fully possible to arrange the fibers of the soft magnetic material under an arbitrary angle to the material Barkhausen effect.

It is optimal when both materials are arranged perpendicular to each other since then the mutual influence is zero. As already explained above, the orientation of the fibers may take place again by a magnetic field, which is subjected mass still wet pulp during the manufacturing process.

According to an advantageous development, it is envisaged structure deactivatable security element according to the invention. This requires providing a magnetic material of medium or high remanence preferably as laminitis. These slats are arranged in the vicinity of the material, in the form of strip or wire, with Barkhausen effect. For the deactivation of these magnetically soft fibers are provided, according to a preferred security element according to the invention, with a magnetic coating medium or high remanence improvement.

Deactivation takes place in known manner, thanks to the magnetic material of medium or large remanence is subjected to a correspondingly strong magnetic field so that is brought to saturation.

International

If deactivatable structure only one of the two materials, such as magnetically soft fibers, this efectl that, in the case of deactivation, the security element remains optimally detectable in a surveillance system Barkhausen. If both materials are assigned to deactivators materials medium or large remanence, then the security element can be disabled for both types of surveillance systems.

Preferably deactivator materials for soft magnetic material and the Barkhausen material with high defect are different in nature. Efecyo invention is explained on the basis of the etecto that follow. En los dibujos, las figuras muestran: In the drawings, the figures show: Fig 1a shows a perspective representation of a surveillance system S1 for Barkhausen security elements 1, while Fig.

Both from the point of view of the structure efrcto well as the general mode of operation, both surveillance systems S1, S2 have a great similarity. The differences are only in the detail. The transmitter device 4 emits an interrogation field H in the interrogation zone 6 to be protected.

Material 1 in strip form or wire with Barkhausen effect or fibers 2 is magnetically soft or are excited s by the evecto field H for emitting a characteristic signal signal 1, signal 2. While the interrogation frequency Barkhausen surveillance system S1 is in the band of low frequencies eg. As already stated in the introduction of the description the interrogation frequency high frequency harmonics S2 surveillance systems can also be modulated by a frequency interrogation low frequency.

This evaluates the signals signal 1, signal 2 transmitted according to a predetermined algorithm and shoots, optionally, an alarm indicating the presence prohibited an article 10 bakhausen in the interrogation zone 6. While the hysteresis curve in the case barkhsusen material 2 magnetically soft presents, between the two states of opposite efecti, a constant linear transition, in the case of material 1 with Barkhausen effect high transition occurs discontinuously for intensity H field relatively small.

Signals signal 1, signal 2 characteristics of the security elements 1, 2 are modified under the influence of each other security element 2, one only of unessential way. Thus the security element 3 according to the invention is detected equally well by both surveillance systems S1, S2.

In a carrier layer 8 made of cellulose material fibers 2 they are housed magnetically soft.

The fibers 8 can feecto arranged also obviously on the carrier layer 8. The orientation takes place preferably during manufacture of the carrier layer 8 made of cellulose material, in which are housed two magnetically soft fibers.

Una capa portadora 8 hecha de masa de celulosa es fabricada, de manera conocida, en forma de una pista sin fin.

A carrier layer 8 made of cellulose material is manufactured in known manner, as an endless track. To impose on the fibers 2 magnetically soft a preferred direction on the track, a device is provided which generates a magnetic field in the longitudinal direction or running direction of the track. While the track made of cellulose material is in a wet state the fibers 2 will be oriented under the influence of the magnetic field, parallel with respect to magnetic field lines.

Barkhxusen el caso del material 1 con efecto Barkhausen se trata, como se ha descrito ya en varias ocasiones, de una tira o un alambre.

Barkhausen effect – Wikidata

In the case of one material with Barkhausen effect it is, as barkhsusen described several times, a strip or a wire. In case of an arrangement the magnetic fields of both security elements 1, 2 influence at all.

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To reduce baarkhausen demagnetizing factor of the security element 3, which facilitates magnetisability the security element 3 in the interrogation field of monitoring devices S1, S2, are provided in the two lateral areas of the strip or wire made of material with Barkhausen effect 1, 11 side sections. The magnetic properties saturation magnetization, demagnetization factor, privileged direction of the materials used for the side sections 11 are preferably chosen so that the effective demagnetizing factor of the security efcto 3 is reduced optimally.

For this purpose they are arranged immediately next to the material 1 as strips or wires with Barkhausen effect, sections 9 made of magnetic material of medium or high remanence. If these sections 9 are carried by a saturation correspondingly strong magnetic field, then suppress a reaction of the material with Barkhausen effect 1 a monitoring system Barkhausen S1.

Also in the example shown are structured deactivatable also magnetically soft amorphous fibers 2. In the simplest case this happens because the fibers 2 carry a coating 12 of magnetic material of medium or high remanence.

Analogously to the example described abrkhausen, a reaction of the fibers 2 in a magnetically soft surveillance system S2 for security elements 2 magnetically soft as soon as the deactivator barkhaksen is brought to saturation is suppressed. Security element for electronic article formed of a material 1 with Barkhausen effect which is excited by an external magnetic field H1to issue a first signal signal 1 feature, which is recognizable in a surveillance system S1 a soft magnetic material, which is excited by applying an alternating magnetic field H2 to issue a second signal signal 2 feature which is recognizable in a surveillance system S2wherein the components of maximum signal of both materials 1; 2 are in frequency bands F1, F2 different and wherein the signal components of a material 1; 2 are in each case negligibly small in the frequency band F2; F1 in which the signal component of the other material efexto 1 is at a maximum level.

A security element for electronic article formed of a material 1 with Barkhausen effect which is excited by an external magnetic field H1to issue a first signal signal 1 characteristic, which it is recognizable in a surveillance system S1 a soft magnetic material, which is excited by applying an alternating magnetic field H2 to issue a second signal signal 2 feature which is recognizable in the system monitoring S2wherein the components of maximum signal of both materials 1; 2 are in frequency bands F1, F2 different and wherein the signal components of a material 1; 2 are each negligibly small in the frequency band F2; F1 in which case the signal component of the other material 2; 1 is at a maximum level.

Security element according to claim 1, wherein the material with Barkhausen effect exists as a strip or wire and wherein the soft magnetic material exists in the form of fibers, which are embedded in a mass of cellulose or they are arranged on a cellulose material. Security element according to claim 1 or 2, characterized in that there are provided further elements 11 magnetically soft which are arranged in the side areas of at least one of the two materials 1; 2.

Security element according to claim 1, 2 or 3, characterized in that the materials barkhaussen, 2 are arranged relative to each other, or spaced apart, such that their interaction is minimal.

Security element according to claim 2, wherein the Barkhausen material 1 in strip form or wire, and fibers 2 in the carrier layer 8 made of cellulose material are oriented substantially parallel to one yes.

Security element according to claim 2, wherein the Barkhausen material 1 in strip form or wire, and fibers 2 in harkhausen carrier layer 8 made of cellulose material are disposed at an angle arbitrary one another. Security element according to one or more of the preceding claims, wherein both materials 1; 2 are structured deactivatable manner. DE DEA1 en Ferromagnetic fibers having use in electronical article surveillance and method of making same.

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Method and apparatus for deactivating targets used in electromagnetic type article surveillance systems. Multi-directionally responsive, dual-status, magnetic article surveillance marker having continuous keeper.

Rf and sonic systems for preventing shoplifting of goods and unauthorized removal of capsules affixed thereto for protecting goods. Amorphous magnetostrictive alloy with low cobalt content and method for annealing same. Method and apparatus for producing uniform electromagnetic fields in an article detection system.