EP0657903B1 - Method of winding a core having an electronic component and means for guiding wires connecting a coil with the electronic component - Google Patents

Abstract

The coil core (2) described includes means (24A, 24B, 24C, 25A, 25B, 25C) for guiding the coil wire (3) making it possible to lead the ends of the wires of the coil (30) directly above metal tracks (41, 42) of one or more electronic components (4) fixed to the core. In this way, it is possible to use a simplified winding machine (1), that is to say one not including mobile means for guiding the wire, and the movements of the winding head (12) of which are thus simplified. <IMAGE>

Description

The present invention relates to a winding method, particularly a method of producing a coil of fine wire on a core, on which is mounted at least one electronic component comprising at least two metal tracks to be connected at the two ends of the coil. The coil in question here is produced using a wire of small diameter, generally between approximately 0.020 mm and approximately 0.12 mm on enamelled insulation and the electronic component typically has dimensions of the order of 1 mm x 1 mm with a thickness of approximately 0.5 mm, the metal tracks to be connected having dimensions of a few tenths of mm. The diameter of the core is here of the order of 10 to 50 mm, for a length of coil, a non-critical value, which can be from a few mm to about ten mm. The invention also relates to the core which can be wound by this method.

In some transponder or transponder applications for high frequency identification systems, an electronic component is connected to a coil, which then acts as a tuned antenna for a certain response frequency. Among these applications, there are some where the electronic component is rigidly fixed to the core of the coil. Given the small dimensions of the metal tracks and the low mechanical resistance of the winding wire, very sophisticated means must generally be provided to bring the two ends of the coil wire exactly opposite said metal tracks to fix them there, preferably by welding. In general, and in the case where the wires are bonded to the machine winding, it is equipped with guide means of the wire, generally mobile, in order to bring it, when it is unwound from the winding head, in position to be fixed on the metal tracks.

EP-A-0.432.239 describes a method of winding a core provided with two metal tracks to be connected at the two ends of the coil. By this process, the wire is guided by mobile guide means, some of them being arranged on the rotary table holding the cores to be wound, while others depend on the movement of the Flyer responsible for winding the wire. Although the method described here is a clear improvement on what existed before, the need for these movable guide means increases the complexity of the winding machine, consequently its cost, and decreases its production rate as well as its reliability.

A method of winding a coil core provided with an electronic component according to the preamble of claim 1, as well as a coil core provided with an electronic component according to the preamble of claim 3 are also described in EP- A-0.405.671. The wires connecting the coil to the component follow two parallel paths oriented along the longitudinal axis of the coil. The winding process described in this document is relatively complex and although the means necessary for this purpose are not described, the person skilled in the art understands that the winding head must be capable of carrying out winding along the longitudinal axis. of the core and that either the winding head itself or fairly sophisticated guide means must be able to make wire attachments, by winding the latter around fasteners, this along radial axes perpendicular to the longitudinal axis. The need for these complex winding means is a major drawback of this process. Due to the alignment of the guide means specific to the core along the longitudinal axis of the latter, these means do not can be only very small, therefore requiring very precise guiding of the wire and therefore a winding head driven with very high precision. In addition, the winding core consists of several parts made of different materials, assembled together, thus constituting a relatively expensive component.

An object of the present invention is therefore to propose a method of winding a core supporting an electronic component, by which the input and output wires of the coil are suitably guided to pass over the metal tracks of the electronic component. , this by simple guiding means, that is to say fixed, using a winding head performing only simple movements and not requiring high course accuracy.

Another object of the invention is to provide a core supporting an electronic component which can be wound by the above method, this core which can be obtained by simple manufacturing methods, as well as a transponder equipped with such a core.

In order to achieve these aims, the invention provides a winding method according to claims 1 to 2, a coil core having the characteristics of claims 3 to 10, as well as a transponder according to claim 11.

• la figure 1 représente une vue par dessus simplifiée d'une portion de machine de bobinage travaillant selon le procédé de l'invention,
• la figure 2 représente une première forme d'exécution d'un noyau de bobine selon l'invention, vu par dessus,
• la figure 3 représente une deuxième forme d'exécution d'un noyau de bobine selon l'invention, vu par dessus,
• la figure 4 représente une coupe selon la ligne IV-IV du noyau de la figure 2,
• la figure 5 représente une coupe partielle selon la ligne V-V de la figure 4, et
• la figure 6 représente une vue partielle par dessus d'un noyau de bobine comportant plus d'un composant.

To better understand the invention, reference may be made to the description which follows, as well as to the appended drawing comprising the figures in which:

• FIG. 1 represents a simplified top view of a portion of a winding machine working according to the method of the invention,
• FIG. 2 represents a first embodiment of a coil core according to the invention, seen from above,
• FIG. 3 represents a second embodiment of a coil core according to the invention, seen from above,
• FIG. 4 represents a section along line IV-IV of the core of FIG. 2,
• FIG. 5 represents a partial section along the line VV of FIG. 4, and
• FIG. 6 represents a partial view from above of a coil core comprising more than one component.

In Figure 1 we see a winding machine 1 comprising in particular a rotary table 10 whose periphery is provided with a plurality of attachment points 11 of coil cores 2. The attachment points 11 may for example be each consisting of a portion of rod projecting radially relative to the periphery of the rotary table 10, these portions of rods comprising means making it possible to orient all the cores 2 in the same way around their longitudinal axis, for example, and at case where the rod portions are of circular section, by providing them with a flat so as to adapt to the shape of a longitudinal hole passing through the core (see FIG. 4). Any other means making it possible to hold and orient all the cores 2 on the rotary table 10 at the same angle can obviously be used. Similarly, the method and the core according to the invention also adapt when the winding machine 1 does not include the rotary table 10, but where all the cores 2 are arranged side by side on a slender element; in this case the relative movements between the cores 2 and the winding head 12 described below will be adapted accordingly. The winding machine 1 therefore comprises a winding head 12, preferably of the flyer type, comprising in particular a wire-carrying coil 12A as well as a wire conducting arm 12B comprising drive means (not shown), making it possible to impose a rotational movement on it around a radial axis relative to the rotary table 10, to block it according to several angular positions determined around this axis, as well as to impose translational movements as well as stops along said axis. As shown in FIG. 1, the rotary table 10 successively has a core 2 to be wound in front of the head 12, the winding wire 3 passing from an already wound core to the core to be wound, led by the driving arm 12B and guided by guide means which will be described below, passing over the first metal track of the electronic component, carrying out the winding, passing over the second metal track and then being led to the next core to be wound. Such a winding machine is generally supplemented with means (not shown) enabling the wires to be welded to the metal tracks of the electronic components. After the welds of the two end wires of a coil have been made, other means (not shown) cut or tear off the portions of wires connecting two successive coils in order to separate them. In the winding machines according to the prior art, mobile guide means, forming part of the rotary table 10 and / or arranged near the winding head 12, are responsible for conducting the wire 3 so that it passes exactly over the metal tracks; these guide means are generally mobile and therefore expensive and delicate. In the case where, as represented in the figure, the number of cores 2 on the rotary table 10 is such that during the passage of the wire 3 from a core to the following angle that the wire would make would be very different from an angle of 90 ° to the axes of the cores, complementary means of guide 13 can be provided on the rotary table 10. These means are very simple, being constituted for example of an L-shaped element, one branch of which is fixed on the rotary table 10, between two attachment points 11, the wire 3 being duct to come to rest on the other branch of L. These guide means are not comparable to those mentioned above for the devices of the prior art insofar as they are not mobile and are not essential for the conduct of the winding method according to the invention, in particular in cases where the cores are arranged relatively close to each other or if they are arranged on a long element rather than on a rotary table.

FIG. 2 shows a first embodiment of a coil core 2 according to the invention making it possible to overcome the mobile guide means of the prior art mentioned above. This core is preferably made of synthetic material, preferably obtained in one piece by injection, of generally cylindrical shape, comprising an end part 20 and a winding part 21, these two parts being generally of circular section. The coil also preferably comprises cheeks 22A, 22B and 22C which respectively separate the parts 20 and 21 and limit the other ends of the winding parts 21 and of end 20. A housing 23 is provided on a portion of the periphery of the part end 20, in order to precisely accommodate the electronic component 4. It is composed of an encapsulated circuit 40 provided on one of its faces with two metal tracks 41 and 42 intended to be connected to the ends of the wire constituting the coil 30. Preferably, the depth of the housing 23 is such that the metal tracks 41 and 42 are just flush with or protrude from the envelope cylindrical constituting the end portion 20 (see Figure 4). Opposite the housing 23 and consequently the metal tracks 40 and 41, the end part 20 comprises its own guide means, making it possible to guide the wire 3 and bring it above said metal tracks. These guide means consist, imagining that the wire 3 is brought from above in FIG. 2, of an input guide pad 24A, and of a first lateral guide means 24B, then after the wire 3 has passed over component 4, a second lateral guide means 25B, so that, when the wire 3 is stretched between the lateral guide means 24B and 25B, when making the coil 30, the wire 3 is brought directly above the metal track 41 in a manner which will be described in more detail later. After the coil 30 has been wound, the wire 3 is brought by the wire conducting arm 12B on the other side of the first input guide pad 24A, then along the lateral guide means 24C and 25C and finally on the output guide pad 25A, from where, being tensioned again, it is automatically positioned directly above the metal track 42 as before. As can therefore be seen in the figure, the guide edges of the lateral guide means 24B and 25B are aligned with respect to the metal track 41, while those of the guide means 24C and 25C are aligned with the metal track 42 In the case of FIG. 2, the lateral guide means 24B, 25B, 24C and 25C consist of bulges of the cheeks 22A and 22C, the exact shape of which will be described below.

Figure 3 shows another embodiment of a coil core 2 according to the invention. This embodiment is particularly suitable in case where the cheek 22C limiting the end of the end part 20 of the core is not necessary. In this case, the lateral guide means 24C and 25C, as well as possibly also those noted 24B and 25B, consist of pins whose exact shape is described below.

The forms according to vertical section planes mutually perpendicular to the above guide means are shown in Figures 4 and 5. In Figure 5, there are the lateral guide means 24B and 24C, consisting of bulges of the cheeks 22A and 22C , these bulges comprising a first upper part of semi-conical shape superimposed on a lower part of semi-cylindrical shape. We also distinguish in the figure the input guide pad 24A, also composed of a conical upper part and a cylindrical lower part.

When the wire feed arm 12B of the Flyer brings the wire 3 above the end portion 20 and lowers it by its rotational movement, it is understood by seeing this figure that the translation position of the Flyer is determined by so that the wire comes to be placed in what appears to be a notch having a general shape of V visible in the figure, the two walls of the V being made up of inclined walls offset from the guide means 24A and 24B. Following the rotational movement of the driving arm 12B, the wire 3 is brought in the same way into a V similar to the previous formed by the inclined walls of the guide means 25A and 25B (not visible in this figure) arranged after the component 40. Continuing its rotational movement and when, by a translation of the driving arm, the wire 3 is driven in order to pass through a passage notch 26A of the cheek 22A (see FIG. 4), in order to pass over the part winding 21 to perform the winding 30, the wire 3 is led to the bottom of said successive V-shaped notches and from there on the cylindrical parts constituting the lower portions of the guide means 24A and 24B as well as 25A and 25B. The cylindrical faces of the lower portions of the lateral guide means 24B and 25B are arranged so that when the wire 3 is stretched between them, it is placed exactly in line with the metal track 41.

This is also shown in Figure 4, which is a section along the line IV-IV of Figure 2, where we see the wire 3, kept taut from the previous core, which was brought behind the input guide means 24A, in front of the lateral guide means 24B and 25B, then taken through the passage notch 26A, which had the effect of stretching the wire 3 and passing it from the conical upper parts of the guide means to the lower parts cylindrical in order to bring it down to the level of the metal track 41. After the winding has been carried out, the wire 3 will pass from the winding part 21 to the end part 20 through the passage notch 26B and will be led in front the inlet guide means 24A, the lateral guide means 24C and 25C then in front of the outlet guide means 25A (see FIGS. 2 and 3), then taken to the next core to be wound. These last operations have the same effect on this portion of wire, that is to lower it in the same manner as described above towards the metal track 42. If during the operations described here the wire 3 does not come into direct contact with the metal tracks and there is a slight space, this contact will be obtained later when the welding tips press on the wire and fill the remaining space.

The process described above is exactly similar for the embodiment of the kernel according to Figure 3.

Figure 4 clearly shows the general shape of the guide means, composed of a conical upper portion (Figure 3) or semi-conical (Figure 2) and a lower portion respectively cylindrical or semi-cylindrical. It can be seen that these guide means are generally projecting from the cylindrical surface of the end portion 20, preferably being parallel to each other. As can also be seen in FIGS. 2 and 4, the inlet guide means 24A is of circular section while the outlet guide means 25A is of oval section or having the shape of a convex lens. This in fact represents two alternative embodiments, it being understood that the inlet and outlet means are preferably of the same shape, whether it is one or the other. It can also be seen in FIG. 4 that instead of two passage notches 26A and 26B, there may be only one passage notch 26C serving for the passage of the wire in both directions. FIG. 4 also shows the central hole 27 provided with the positioning flat 27A indicated above.

As indicated above, the core 2 is preferably obtained by injection of a synthetic material, the guide means 24A, 24B, 24C, 25A, 25B and 25C as well as the housing 23 being directly obtained during this manufacturing operation; as a variant, it is also possible that for the guide pads, some of them consist of elements added to the core 2.

FIG. 6 shows an embodiment of the core 2 comprising two successive housings 23 in order to have two components side by side 4 comprising metal tracks to be connected together and with the winding. These two components can be either two components comprising identical circuits, either two components comprising different circuits or it may be a component comprising a circuit and a passive element such as a resistor or a capacitor. The constraints are that the housings 23 have a shape adapted to receive these components and that each of them comprises two metal tracks which are aligned two by two on the end part 20 of the core. We can also have more than two components with the same constraints as above.

When the winding operations are finished and the wires have been soldered on the corresponding metal tracks, and when the same operations have been done on the next core, the ends of the wires can be cut or torn off below the first track and in beyond the second, preferably by automatic means forming part of the winding machine. It is necessary to ensure that the wires are pulled out so that the other end of the wire is already welded to a metal track of the component placed on the next core in order to keep the wire stretched for the winding operation described above.

The wire removal operation has been described, in relation to FIGS. 2 and 3, with the wire passing first along the lateral guide means disposed on the side of the cheek 22A separating the parts 20 and 21 of the core and then along opposite lateral guide means after the winding has been carried out. It is obvious that the opposite possibility is also possible, as seen in Figure 1.

Each component 4 is held at the bottom of its housing 23 by the ends of the wires which press it from two opposite sides against this housing bottom; this type of support is generally sufficient given the very low mass of the component. If, however, this retention is not sufficient, for example for devices subjected to sudden movements, additional holding means can be provided, for example a drop of glue placed at the bottom of the housing 23, or else mechanical holding means , or it is also possible to encapsulate the component on the core by covering it for example with a material melting at low temperature and adhering to the portions of the cylindrical surface of the end portion 20 close to the housing 23. Such a encapsulation is generally not necessary for a core comprising a cheek 22C limiting the end part 20, this cheek offering sufficient mechanical protection to the component.

More generally, the core 2 according to the invention is directly provided with means for guiding the winding wire 3, making it possible to pass the wire directly over the metal tracks of the electronic component or components, these guide means comprising inclined surface portions and rectilinear surface portions so that the wire gradually approaches the metal track on which it is to be welded, under the effect of a tension which is exerted on it or under the effect of pressure applied to it by the welding tips.

Thus, such a core makes it possible to carry out a winding on a winding machine comprising no movable guide means for the wire, possibly even under certain conditions comprising no guide means, these being transferred to the core. This makes it possible to work with relatively simple winding machines, the movement control of the Flyer is also relatively simple since the latter only rotates in one direction and since its longitudinal movement control may not require great precision of positioning. The additional cost of the injection mold caused by the need to provide the guide means on the core is largely offset, given the high number of cores produced, by the savings made on each winding machine. Another advantage of the method and of the core according to the invention is that the guide means cannot be adjusted since they are fixed and integrated into the core.

Claims (11)

1. Process for winding a core (2) comprising a first portion (20) provided with at least one recess (23) in which there is lodged at least one electronic component (4) provided with two metal paths (41, 42) and a second portion (21) about which the winding is to be carried out, said process having the following two steps: before and after a winding head (12) carries out a winding (30) about said second portion (21) of said core, the winding head (12) causes the two portions of wire (3) corresponding to the ends of the coil (30) to pass along guide means (24A, 24B, 24C, 25A, 25B, 25C) disposed on said first core portion (20), each portion of wire being then guided by said guide means in such a way as to be positioned facing a metal path (41, 42) of each electronic component, characterized in that each portion of wire is thus guided along a direction parallel to the direction of the turns of the coil (30) produced on said second portion (21) of core and is guided in such as way as to be positioned on or in the immediate proximity above a metal path (41, 42) of each electronic component when the wire is taut.
2. Winding process according to claim 1, characterized in that said winding is carried out on a winding machine (1) comprising a Flyer-type winding head (12), said winding machine not comprising any other movable means for guiding the winding wire (3).
3. Coil core (2) for application of the process according to one of the preceding claims, including a first portion (20) provided with at least one recess (23) in which is placed at least one electronic component (4) provided with two metal paths (41, 42) flush with the surface of said first portion, and a second portion (21) on which a winding (30) is to be carried out as well as guide means (24A, 24B, 24C, 25A, 25B, 25C) capable of guiding the wire (3) in order to position it facing each first (41) of said metal paths before the winding and each second (42) of said metal paths after the winding, characterized in that said guide means are disposed on either side of said recess or recesses along a direction parallel to the direction of the turns of the coil and comprise inclined guide surfaces and guide surfaces perpendicular to the plane of the metal paths (41, 42) permitting the wire (3) to be guided along the same direction parallel to the direction of the turns of the coil in order to lead it on or in the immediate proximity above said metal paths.
4. Core coil (2) according to claim 3, characterized in that the guide means (24A, 24B, 24C, 25A, 25B, 25C) are made up of a lead-in guide means (24A), a lead-out guide means (25A), as well as lateral guide means (24B, 24C, 25B, 25C), a portion of the side faces of first lateral guide means (24B, 25B) being aligned in relation to each first metal path (41), a portion of the side faces of second lateral guide means (24C, 25C) being aligned in relation to each second metal path (42).
5. Coil core (2) according to claim 4, characterized in that the first lateral guide means (24B, 25B) and/or the second lateral guide means (24C, 25C) are composed of bulges of a flange (22A, 22C) of said core.
6. Coil core (2) according to one of the claims 4 or 5, characterized in that the first lateral guide means (24B, 25B) and/or the second lateral guide means (24C, 25C) are composed of guide studs, projecting from the surface of said first core portion (20), being disposed perpendicular to the plane of the metal paths (41, 42).
7. Coil core (2) according to one of the claims 4 to 6, characterized in that said lead-in and lead-out guide means (24A, 25A) are composed of guide studs, projecting from the surface of said first core portion (20), being disposed perpendicular to the plane of the metal paths (41, 42).
8. Coil core (2) according to one of the claims 4 to 7, characterized in that the guide means (24A, 24B, 24C, 25A, 25B, 25C) comprise an upper portion of conical or semiconical shape and a cylindrical or semicylindrical lower portion.
9. Coil core (2) according to one of the claims 4 to 8, characterized in that means (26A, 26B, 26C) for guiding the wire from the first portion (20) of the core toward the second portion (21) and vice versa are further contrived on an intermediate flange (22A) separating the two said portions of the core.
10. Coil core (2) according to one of the claims 4 to 9, characterized in that it is made in one piece by injection of a synthetic material.
11. Transponder for identification system provided with a core according to one of the claims 3 to 10.

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