WO2000002210A1

WO2000002210A1 - Magnetic device, method and apparatus using same, in particular for reading and displaying a message

Info

Publication number: WO2000002210A1
Application number: PCT/FR1999/001464
Authority: WO
Inventors: Jacques Landrevie
Original assignee: Landata-Cobiporc
Priority date: 1998-07-01
Filing date: 1999-06-17
Publication date: 2000-01-13
Also published as: EP1092225A1; FR2780849B1; FR2780849A1

Abstract

The invention concerns a magnetic device consisting of tiered single-unit modules (M1, M2, M3) in the form of plates, having on both their surfaces printed electromagnetic coils in the form of turns. Said device modules (M1, M2, M3) are arranged such that the lines mutually connecting the coils do not encroach on the space available therefor. The invention also concerns a method and an apparatus using said device for reading and displaying a message.

Description

MAGNETIC DEVICE, METHOD AND APPARATUS USING THE SAME, PARTICULARLY FOR READING AND VIEWING A MESSAGE

The present invention relates to a magnetic device consisting of a superposition of unitary modules in the form of plates, on the two faces of which are printed magnetic coils in the form of spirals.

It also relates to a method and a device for reading a message made of a material containing magnetic substances deposited on a non-magnetic support, or conductive elements on an insulating support.

In particular for manufacturing magnetic memories of computers, it is known to produce magnetic modules made up of coils (or inductors) juxtaposed, arranged according to a two-dimensional matrix and electrically connected by conductors which extend according to the orthogonal coordinates of the matrix . This allows the individual supply of each of the coils of the matrix.

When it is necessary to produce a large number of coils with a high number of turns on a reduced surface, the difficulty which one is rapidly confronted lies in the reduction of the dimensions of the windings, generally manufactured with wire wound on a mandrel.

It is of course known to constitute so-called "printed" windings, produced by photoengraving on the (or) face (s) conductive (s) of an insulating support (printed circuit). When it is necessary to increase the number of turns on the printed circuit, in particular to raise the value of magnetic fields thus generated, one comes up against the narrowness of the available surface. Multilayer circuits are then produced, by superimposition and connection between them of modules of the same type. However, the number of turns is also limited because the area occupied by the connections of the coils between them reduces the space available for the turns.

The object of the present invention is precisely to overcome this drawback, that is to say to propose a magnetic device consisting of a superposition of unitary modules in the form of plates, on the two faces of which are printed magnetic coils in the form of spirals, which allows for multi-layer circuits without being hindered by the connections of the coils of the different layers to each other. Another objective is to propose a method and an apparatus making use of this device, which makes it possible to read and visualize a message written in material containing magnetic particles on a non-magnetic support or using conductive elements on an insulating support. According to the invention, the aforementioned device is characterized in that: a) the number of modules is odd; b) the modules are of identical surface and have a square shape; c) on each module and on each side thereof, the coils are printed to form a two-dimensional matrix made of n ² individual coils with n> 2, distributed in n rows of n coils, so that the matrix affects an outline square; d) the dies of the same module are superimposed, and the coils which make up its upper and lower faces are wound in pairs around a same axis perpendicular to the plane of the module; e) in each of the dies, the outer conductors of the coils of the same row are joined by a common conductive line, the lines of the rows of the same face being parallel; f) the conductive lines present on the two faces of the same module are arranged orthogonally; g) the center of each coil on one side of a module is electrically connected to the center of the coil on the other side, on the same axis; h) the dies are offset with respect to the center of each module, so that two of their contiguous edges are distant by the same distance di from the corresponding contiguous edges of the module and that the other two edges are distant by the same distance d ₂ of the two other corresponding adjacent edges of the module, with d ₂ > dι, which provides a so-called connection area in the form of

"L" of width d ₂ ; i) the conductive lines extend on each face as far as the connection zone; j) the modules are superimposed after rotation of 90 ° in the same direction around an axis passing through the center of the dies; k) the conductive lines of a module, in the connection area, are connected to the conductive lines of the module immediately above and / or immediately below, the unconnected lines of the modules below and above the superposition respectively constituting the inputs and the electrical outputs of the device. According to other preferred but non-limiting characteristics of this device:

- the coils that make up each of the dies are identical;

- the coils that make up the dies are different; - the coils of the same module are identical, while those of an immediately adjacent module have a different number of turns;

- the coils on one side of a module have a different number of turns from the coils on the second side;

- Each module has centering holes able to facilitate their stacking on each other.

The invention also relates to a method for reading and viewing a message written in a material containing magnetic particles on a non-magnetic support, or with conductive elements affixed on an insulating support. This process is characterized by the fact that it consists in: - successively supplying electric current to each of the coils of a device as described above, so as to generate a magnetic field therein, while said device is sufficiently close to said message so that the magnetic particles / conductive elements which it contains affect the magnetic field of the coils arranged opposite said message; - measure and record each of the magnetic fields emitted by the device individually;

- visualize in the form of a two-dimensional image the recordings thus produced, the fields of the same value corresponding to points of the same color, while those of a different value correspond to a second color.

The invention also relates to an apparatus for reading and viewing a message written in material containing magnetic particles on a non-magnetic support, or with conductive elements affixed on an insulating support. This device comprises: - a device as described above, adapted to be approached sufficiently close to said message so that the magnetic field of the coils located opposite the message is affected by the presence of said particles / said elements:

- Means for successively supplying each of the coils of said device; - Means for measuring and individually recording the magnetic field of each of the coils;

- Means for viewing in the form of a two-dimensional image the magnetic fields measured, this image being formed by the same number of points and according to the same arrangement as the coils of said device;

- the same magnetic field values being displayed in the form of dots of the same color, while the other values are displayed in the form of dots of a second color. In a preferred embodiment:

- Said device is equipped with means able to move it step by step along a plane parallel to the plane of the modules and to measure and record the magnetic fields at each movement;

- It includes means capable of viewing the recordings thus made in the form of a single image.

Other characteristics and advantages of the invention will appear on reading the detailed description which follows of a preferred embodiment. This description will be made with reference to the accompanying drawings in which: - Figure 1 is a simplified and exploded view of a device according to the invention, consisting of a superposition of three modules;

- Figure 2 is a top view of one of said modules;

- Figure 3 is a bottom view of the module of Figure 2;

- Figure 4 is a detailed and enlarged view of certain coils of the module of Figures 2 and 3;

- Figure 5 is a simplified top view of a device according to the invention;

- Figures 6 and 7 are respectively partial top and side views of a device equipped with displacement means in two orthogonal directions;

- Figure 8 is an overview of an apparatus for reading and viewing a magnetic message, using the device according to the invention.

The device represented in FIG. 1 is a device formed by three superimposed modules Mi, M ₂ and M ₃ of similar type. According to the invention and for reasons which will be explained later in the description, the number of modules is odd. We could therefore have represented five or a higher number of modules in Figure 1, but we limited ourselves to three for the sake of clarity. In a manner known per se, each module consists of a plate of insulating material, of the type generally used for printing printed circuits.

According to the invention, these modules have an identical surface and have a square outline. On the upper 1 and lower 2 faces of each module are printed magnetic coils in the form of spirals. These coils are referenced 30 on side 1 and 40 on side 2.

They are printed by a technique known per se in the field of printing of printed circuits. Their shape, as shown in Figure 1, is simply illustrative. Figure 4 attached gives a more realistic idea of the shape of these coils.

The coils of each of the faces 1 and 2 are printed to form dies Fj and F ₂ of 9 individual coils, distributed in three rows 3, respectively 4, of three coils. Of course, the number of coils of each matrix can be different, for example four or sixteen.

In any event and in accordance with the invention, the coils are printed to form a two-dimensional matrix made of n ² individual coils with n> 2, distributed in n rows of n coils, so that the matrix affects a square contour.

According to another characteristic of the invention, the dies Fi and F ₂ of the same module Mi, M ₂ or M ₃ are superimposed and the coils 30 and 40 which make up its upper and lower faces 1 and 2 are wound in pairs around of the same axis XX 'perpendicular to the plane of the module. When the coils of the same module are observed by transparency, those of the upper face are wound in the opposite direction to those of the upper face. The reason will be explained later in the description.

In each of the matrices Fi and F ₂ , the outer conductors of the coils 30, respectively 40 of the same row 3, respectively 4, are joined by a common conductive line 31, respectively 41. It will be noted that the conductive lines of the same face are parallel to each other. However, the conductive lines 31 and 41 present respectively on the two faces 1 and 2 of the same module are orthogonal.

Furthermore, the center of each coil 30 of the face 1 of each module is electrically connected by a conductor 5 to the center of the coil 40, of the same axis XX ', located immediately above.

This is the reason why the winding direction of the coils is different. If it were the same, the magnetic field generated by each coil 30 would be canceled by that of the corresponding coil 40.

All the matrices Fi and F ₂ are offset from the center of each module. This offset is such that two of their contiguous edges are distant by the same distance di, from the corresponding contiguous edges of the module concerned.

In doing so, the two remaining edges are spaced by the same spacing d ₂ from the two other contiguous edges of the module.

The distances di and d ₂ are such (see FIG. 2) that d is greater than di, which provides on each face 1 and 2, large superimposed zones known as connection R, in the general shape of "L", of width d .

The aforementioned conductive lines 31 and 41 each extend in these connection zones. However, due to the fact that these lines, which are perpendicular, they emerge respectively at the level of a branch different from said "L". Although the modules Mi, M ₂ and M ₃ are superimposed, this stacking is done after rotation of 90 ° in the same direction of each module around an axis YY 'parallel to the axis XX', passing through the center of the matrices.

In this way, one of the branches of each "L" of the connection zones R is not vertically in line with the connection zone of the module immediately above or below, but extends beyond the side thereof (this characteristic is particularly visible in Figures 1 and 5).

It is this particular distribution which will be used to connect the modules together, without this interfering with the surface occupied by the coils. As shown in Figure 1, the three modules Mi, M and M ₃ are connected in pairs. This connection is made in such a way that the lower face of a module is always connected to the upper face of the module placed immediately above, so that the field generated by a pair of coils of a module is not canceled by that generated by the corresponding pair of coils of the module located immediately below or above. However, the lines 31 of the module Mi, which are not connected to the corresponding lines of the module M ₂ respectively constituting the electrical inputs Ei, E ₂ and E3 of the magnetic device thus formed.

In the same way, the lines 41 of the module M, which are not connected to the corresponding lines of the module M ₂ respectively constitute the electrical outputs Si, S ₂ and S3 of the magnetic device thus formed.

This is the reason why the number of modules is odd.

Consequently, by supplying electric current to a particular pair of input Ei, E ₂ or E ₃ and of output Si, S or S ₃ , a set of coils 30 and 40 is arranged arranged vertically. This set constitutes in a way a "super" coil whose number of turns is equivalent to the sum of the turns of the individual coils 30 and 40.

Thus, for a stack of three modules, each of which carries on its faces dies Fi and F ₂ of nine coils 30 and 40, each consisting of 7 turns, we obtain 9 "super" coils made of 42 turns (6 x 7).

In the case illustrated so far, the dies 30 and 40 are identical. However, in embodiments not shown:

- the faces of the same module comprise coils with a different number of turns; - the number of turns of the coils of a module is always the same, but that of the coils of the immediately adjacent module is different.

In this way, the device thus obtained constitutes a transformer.

In another variant, the coils of one or more dies can be replaced by magnetic materials, for example of the "ferrite" type, arranged in the axis XX 'of the coils. In this way, we increase the selfic value of each matrix element.

Finally, as shown in FIG. 5, each module Mi, M ₂ comprises, at the periphery of the dies, four holes T intended to facilitate the centering of the modules relative to each other. In these holes are engaged tabs or pegs not shown in the figure.

The invention also relates to a method and an apparatus for reading and viewing a message written in a material containing magnetic particles on a non-magnetic support, using the device described above. In an alternative embodiment, the message can be written using conductive elements on an insulating support. The process is essentially characterized by the fact that it consists of:

- successively supplying electric current to each of the coils of a device as described above so as to generate a magnetic field therein, the device being close enough to the message to be read that the magnetic particles (or the conductive elements) which it contains affect the magnetic field of the coils arranged opposite said message;

- measure and record each of the magnetic fields generated by the device individually;

- visualize in the form of a two-dimensional image formed of the same number of points and according to the same arrangement as the matrices of the device, the recordings thus produced, the same magnetic field values being visualized in the form of points of the same color while the other values are displayed in the form of dots of a second color.

FIG. 6 shows an item of equipment which can be used with the device mentioned above.

This device comprises a frame 6 of square shape inside which is placed a device D made of a stack of modules such as those described with reference to FIG. 1.

Each angle of the device (only one is shown in Figures 6 and 7) is equipped with means capable of moving it according to orthogonal coordinates x and y arranged in the plane of the frame and the device.

These means comprise a part 60 fixed to the frame 6, which receives a vertical shaft 61 capable of being rotated about its own axis.

At the lower end of this shaft is mounted a disc 62 which carries an eccentric 63. The assembly is connected to a guide 66 which can slide freely relative to two orthogonal rods 64 and 65 arranged according to the abovementioned x and y coordinates and fixed in frame 6.

Assuming that the motor means for driving the shaft 61 in rotation operate step by step to successively occupy sixteen different angular positions, the device D will in turn occupy sixteen different positions.

Consequently, if we record the magnetic fields generated by the coils of the dies of the device D, each time that the motor moves step by step, we will be able to operate sixteen different recording series corresponding to x coordinates and there are different. Thus, if each matrix of device D is formed from sixteen rows of sixteen coils, a series of 4,096 records (16 x 16 x 16) is then obtained.

FIG. 8 shows an apparatus for reading and viewing a message written in a material containing magnetic particles on a non-magnetic support.

In the case presented here, it is a message Gi formed of an ink containing magnetic particles, this message being affixed to the upper face of a support Hi such as a cardboard box, that is ie in a non-magnetic material.

The message Gi is arbitrary. It may include alphanumeric signs, drawings, etc. The device is equipped with a device D as described above.

This device D is provided with means not shown adapted to bring it close enough to the message Gi so that the magnetic fields of some of its coils are affected by the magnetic particles of said message. These means can be constituted by a support of any type. Of course, the device D is equipped with electrical supply means able to generate successively in each of its coils an individual field.

The device is also equipped with means 7 connected by a wire link 8 to the device D, these means being able to measure and record each of the individual magnetic fields of the device. These means consist, for example, of an electronic system controlled by a microprocessor.

The apparatus also includes a screen 9 on which an image I can be viewed.

The means 7 are capable, on the basis of the magnetic field recordings made, of reproducing on the screen 9, a two-dimensional image I formed of the same number of points and according to the same arrangement as the matrices of the device D, the same values of magnetic field being displayed in the form of dots of the same color, while the other values are displayed in the form of dots of second color. In this way, the message G'i formed on the screen 9 is completely faithful to the initial message Gi.

The means 7 are able to display an image I grouping together all of the field measurements carried out using the apparatus described with reference to FIGS. 6 and 7. Of course, the higher the number of records, the higher the image quality will be good. However, in the event that the device D is not equipped with means capable of moving it step by step, an image is obtained whose number of points is equal to the number of coils of the dies.

It is possible to make the same recordings with a message G ₂ which is enclosed inside a non-magnetic support H ₂ , insofar as the magnetic particles which it contains are capable of disturbing the magnetic field of the coils.

The device which has just been described thus makes it possible to read a magnetic image, "without light", on most non-magnetic supports. In the variant not shown, the above message is formed of conductive elements such as metal particles on an insulating support. These are, for example, metallic particles on a plastic support.

The phenomenon implemented is that known as "eddy currents". In such a case, induction currents occur in the mass of the conductive elements placed near the magnetic fields.

There are many applications of the apparatus described above.

So we can think of the identification of animals. In such a case, a tattoo is made with an ink charged with magnetic or conductive particles on the skin of the animal. This tattoo can be read thanks to the device even if hairs or dirt have covered the tattoo. In addition, this reading operation is absolutely not traumatic for the animal.

Another application is the reading of "certificates of origin".

Thus, multi-layer products (plywood, laminate panels, etc.), as well as soft products (leather, cardboard, wood) can be marked during their manufacture. This marking using magnetic or conductive ink can even be incorporated into the product.

In this way, an internal manufacturing benchmark is produced which does not alter the surface of the product. However, this mark allows the manufacturer to certify the authenticity of the product by reading said mark (logo, number, etc.) through the thickness of the article.

Another application can be confidential and protected identification. In this case, a magnetic or conductive label can be included inside a product (package, container, clothing, suitcase, etc.) and can only be read visually by an operator equipped with the device as described below. - above. In this way, it will be very difficult for a potential fraudster to modify or delete the brand included in the product without destroying the latter. Finally, another possible application is that of imagery. Magnetic or conductive moving objects or liquids carrying magnetic compounds or moving conductors can be viewed on a screen, using the device as described above.

Claims

1. Magnetic device consisting of a superimposition of unitary modules (Mi, M ₂ , M3) in the form of plates, on the two faces (1, 2) of which magnetic coils (3, 4) are printed in the form of spirals, characterized by the fact that: a) the number of modules (Mi, M ₂ , M ₃ ) is odd; b) the modules (Mi, M ₂ , M ₃ ) are of identical surface and have a square shape; c) on each module (Mi, M ₂ , M ₃ ) and on each face (1; 2) thereof, the coils (3; 4) are printed to form a two-dimensional matrix (Fi, F ₂ ) made of n ² individual coils with n> 2, distributed in n rows of n coils, so that the matrix affects a square contour; d) the dies (Fi, F ₂ ) of the same module (Mi, M ₂ , M ₃ ) are superimposed, and the coils (3; 4) which make up its upper (1) and lower (2) faces are wound in pairs around the same axis (XX ') perpendicular to the plane of the module; e) in each of the matrices (Fi, F ₂ ), the outer conductors of the coils (3, 4) of the same row are joined by a common conductive line (31, 41), the rows of the rows on the same face being parallel; f) the conductive lines (31, 41) present on the two faces of the same module (Mi, M ₂ , M3) are arranged orthogonally; g) the center of each coil (3; 4) on one side (1; 2) of a module is electrically connected to the center of the coil on the other side, of the same axis; h) the matrices (Fi, F ₂ ) are offset from the center of each module, so that two of their contiguous edges are distant by the same distance di from the corresponding contiguous edges of the module and the other two edges are spaced by the same distance d ₂ from the two other corresponding contiguous edges of the module, with d ₂ > di, which provides a so-called "L" -shaped connection zone (width D ₂₎ ; i) the conductive lines extend on each face as far as the connection zone; j) the modules are superimposed after rotation of 90 ° in the same direction, around an axis (YY ') passing through the center of the matrices (Fi, F ₂ ); k) the conductive lines of a module, in the connection area, are connected to the conductive lines of the module immediately above and / or immediately below, the unconnected lines of the modules below and above the superposition respectively constituting the inputs ( Ei, E ₂ , E ₃ ) and the electrical outputs (Si, S ₂ , S3) of the device.

2. Device according to claim 1, characterized in that the coils (3; 4) which make up each of the dies (Fi, F ₂ ) are identical.

3. Device according to claim 1, characterized in that the coils (3; 4) which make up the dies (Fi, F ₂ ) are different.

4. Device according to claim 3, characterized in that the coils (3; 4) of the same module are identical, while those of an immediately adjacent module have a different number of turns.

5. Device according to claim 3, characterized in that the coils (3; 4) of a face (1; 2) of a module have a number of turns different from the coils (3; 4) of the second face (2; 1).

6. Device according to one of claims 1 to 5, characterized in that each module (Mi, M ₂ , M ₃ ) has holes (T) for centering capable of facilitating their stacking on each other.

7. Method for reading and viewing a message (Gi, G ₂ ) written in a material containing magnetic particles on a non-magnetic support (Hi,

H ₂ ), or a material with conductive elements on an insulating support, characterized in that it consists of:

- successively supplying electric current to each of the coils (3; 4) of a device (D) according to one of claims 1 to 6, so as to generate a magnetic field therein, while said device (D) is sufficiently close to said message (Gi, G ₂ ) so that the magnetic particles or the conductive elements which it contains affect the magnetic field of the coils (3; 4) arranged opposite said message;

- measure and record individually each of the magnetic fields emitted by the device (D);

- visualize in the form of a two-dimensional image (I) the records thus produced, the fields of the same value corresponding to points of the same color, while those of a different value correspond to a second color.

8. Apparatus for reading and viewing a message (Gi, G) written in material containing magnetic particles on a non-magnetic support (Hi, H ₂ ), or a material with conductive elements on an insulating support, characterized in that it comprises:

- A device (D) according to one of claims 1 to 6, adapted to be approached sufficiently close to said message (Gi, G ₂ ) so that the magnetic field of the coils located opposite the message is affected by the presence of said particles or said elements;

- Means for successively supplying each of the coils of said device;

- means (7) for individually measuring and recording the magnetic field of each of the coils;

- Means (9) for viewing in the form of an image (I) the magnetic fields measured, this image being formed by the same number of points and according to the same arrangement as the coils (3; 4) of said device;

- the same magnetic field values being displayed in the form of dots of the same color, while the other values are displayed in the form of dots of a second color.

9. Apparatus according to claim 8, characterized in that: - said device is equipped with means (60-65; 7) capable of moving it step by step along a plane parallel to the plane of the modules (Mi, M ₂ , M ₃ ) and to measure and record the magnetic fields at each movement;

- It includes means (9) capable of viewing the recordings thus made in the form of a single image (I).