FR2530874A1 - Anti-interference flexible electrical connection device. - Google Patents

Abstract

The present invention relates to an electrical connection device which is flexible and rendered immune from interference. The device is composed of an electrically insulating, generally flat, flexible and thin support 10 which carries at least one narrow and electrically conducting strip 20 extending over its entire length as well as an electrically conductive coating, which is separated from the said electrically conducting strip 20 and having a width such that when the flexible support 10 is folded at least twice on itself, substantially parallel to the said electrically conducting strip, the latter is surrounded by the covering which then forms a screening member.

Description

 The present invention relates to electrical conductors.

 The present invention relates more precisely to an electrical connection device, flexible and suppressor.

 Flexible conductors have already been proposed for a long time, intended to link together two electrical or electronic elements or circuits, provided with a shield capable of rendering these conductors insensitive to the surrounding parasitic signals.

 According to a first alternative embodiment, suppressed supple electrical electrical conductors are thus made up of a central conductive element, substantially circular, encased in an insulating sheath, itself covered with a conductive shield, on which an envelope is disposed. exterior insulation. By connecting together several external insulating envelopes, it is thus possible to produce electrical connection systems, anti-interference, with multiple conductors. Conventionally in itself, the central conductive element can be made up either of a single metallic wire, or of a plurality of guwtaposed, or even twisted, metallic wires.

 However, such a connection system has many drawbacks. For example, to prepare such a system, it is necessary to strip each of the ends of the conductive elements, making accessible both the metal shield and the central conductive element, so that each of these elements is connected to the part corresponding electronic circuit. It is understood that such preparation of the ends of the connection system proves to be particularly complicated, in particular when the system comprises many conductors.

In practice, it is found that it is frequent that the actual conductive elements are damaged, for example by shearing them, when these electrical conductors are stripped of the insulating and shielding layers covering them. Of course, such a phenomenon significantly reduces the reliability of the assembly.

In addition, such a system, as soon as it composes more than two conductors, has a completely prohibitive manufacturing cost for the use of this system in many devices and in particular so-called consumer devices called have significant development. In addition, it turns out that such connection systems exhibit excessive rigidity for certain applications.

 An attempt has been made to simplify the systems described above, by proposing a second alternative embodiment of interference-reducing electrical connection devices, consisting of internal conductive elements of generally cylindrical section, each surrounded by an individual insulating sheath, all of the internal conductors thus coated with an individual insulating sheath being inserted in a common metal shield, itself covered with an outer insulating envelope.

 Such an arrangement which uses a common single shielding tends to lower the manufacturing cost of the conductive elements while increasing the reliability of the latter. However, there are again most of the drawbacks mentioned above. In particular, to prepare the ends of the connection systems, it is necessary to strip each of the layers constituting them, so that there is access both to the metal shielding and to the internal conductive elements which 'turns out to be complex - and leads, in practice, to deterioration of the internal conductive elements, - when these are stripped of the layers of material covering them.

 Finally, here again, the cost of manufacturing electrical connection systems comprising a plurality of conductors proves to be entirely prohibitive, and such systems have an unacceptable rigidity for a large number of applications.

 There is therefore a need, on the market, to have electrical connection devices which are both flexible, correctly suppressed, while being robust, reliable and economical.

In addition, it would be desirable for such devices to be simple to prepare and easy to install, to have relatively small dimensions, regardless of the number of conductors chosen.

 The present invention proposes a new electrical connection device, which perfectly solves the problems previously posed, and which more precisely consists of an initially planar support, flexible and thin, electrically insulating, which carries at least one narrow electrically conductive strip, extending over its entire length, as well as an electrically conductive coating, separated from said electrically conductive strip, also extending substantially over the entire length of the support, and having a width such that when the flexible support is folded at least two times on itself substantially parallel to said electrically conductive strip, the latter is surrounded by the coating which then constitutes a shield.

 Preferably, the narrow strip and the electrically conductive coating are arranged on the same face of the flexible support.

 According to a preferred embodiment, the flexible support is folded at least twice on itself so that the coating constituting a shield is placed on the outside.

 According to a characteristic of the present invention, the flexible support is a thermoplastic resin, such as polyethylene terephthalate.

 According to another characteristic of the present invention, the narrow strip and the electrically conductive coating are metallic conductors, and preferably copper.

 According to a particular embodiment, a dielectric body is inserted between the different layers of the flexible support, when the latter is folded back on itself.

 According to a first variant, the flexible support is immobilized in the folded position by ultrasonic welding.

 According to a second variant,. # The flexible support is immobilized in the folded position thanks to an adhesive element.

 According to a third variant, the flexible support is immobilized in the folded position, thanks to a mechanical fixing element.

 According to a fourth variant, the flexible support is immobilized in the folded position, by insertion into a heat-shrinkable sheath.

Other characteristics and advantages of the present invention will appear on reading the detailed description which follows, and with reference to the appended drawings given by way of nonlimiting example, which should be considered as incorporated into the description by the reference which is made to them here, and on which
FIG. 1 represents a perspective view of an electrical connection device according to the present invention,
- Figure 2 shows the device of Figure 1 according to a side view, as dried with the arrow referenced II in this same figure 1
FIG. 3 represents a cross-sectional view of an electrical connection device according to the present invention, assembled on two electronic circuits, and schematically illustrates the assembly of the device,
FIG. 4a represents a plan view of an electrical connection device according to the present invention, and
FIG. 4b represents a folded view of this same device,
FIG. Sa represents a plan view of another electrical connection device according to the present invention, and
- Figure 5b shows a view in the folded position of the same device.

 As shown in Figures 1, 2, 4 and 5, the electrical connection device 1, according to the present invention consists of a support 10, initially substantially planar, flexible and thin, electrically insulating, which carries two strips 20 narrow and electrically conductive. As shown in the figures, the two narrow bands are generally straight and parallel.

The strips 20 thus extend over the entire length of the support 10. In addition, the support 10 carries an electrically conductive coating 30, separates from said electrically conductive strips 20. The coating 30 also extends practically over the entire length of the support 10. As shown in FIG. 2, the electrically conductive coating 30 has a width such that when the flexible support 10 is folded over it at least twice -same, said conductive strips 20 are surrounded by the coating 30, which then constitutes a shield.

 More precisely, as shown in the figures, the covering 30 has a width twice the width of the zone occupied by the two strips 20. More precisely still, the covering 30, and the support part 10 carrying the latter , has, on the half of its width closest to the strips 20, a length equal to that of the strips 20, while on its other half, the covering 30 as well as the support 10 which carries it has a shorter length.

 Thus, when the strips 20 and the covering 30 are arranged on the same face of the flexible support 10, as shown in the figures, it is obtained during the folding, if the covering 30 is outside, that the strips 20 are accessible to each of the device's ex-droppings, on one side thereof, while the coating 30 is also accessible at each of the ends of the device, but on the other side.

 Of course, the narrow conductive strips 20 and the electrically conductive coating 30 can be arranged on opposite faces of the flexible support 10.

 Preferably, as also shown in Figure 2, the flexible support is folded at least twice on itself, so that the coating 30 constituting a shield is disposed on the outside.

 According to a preferred embodiment, the flexible support 10 of the electrical connection devices in accordance with the present invention consists of thermoplastic resin, and more precisely of linear polyesters.

 According to a particular embodiment, the flexible support 10 is polyterephthalate, ethylene, which is sold - in particular under the registered trademark "MYLAR" by the firm DU PONT DE NEMOURS.

 On the other hand, the narrow strips 20 and the coating 30 which are electrically conductive are metallic conductors and preferably copper.

 The conductive elements 20 and 30i can be deposited on the flexible support 10, -and delimited by any conventional technique well known to those skilled in the art, such as for example by screen printing.

 Of course, the number of conductive strips 20 disposed on the flexible support 10 is in no way limited.

 On the other hand, in order to eliminate or limit the capacitive coupling effects which may exist between the narrow electrically conductive strips 20 inside and the external shielding 30, - it may be advantageous to insert a dielectric body between the different layers of the flexible support 10, when the latter has been folded back on itself.

 On the other hand, it is necessary to fix the flexible support 10, when the latter has been folded at least twice on itself, so that the electrically conductive coating 30 then constitutes a shield.

 By way of example, the flexible support, when it is formed in particular from a thermoplastic material, can thus be immobilized in the folded position by ultrasonic welding. Reference will usefully be made to the detailed description which follows of the device shown in Figures Sa and 5b, specially adapted for this purpose.

 According to a second variant, the flexible support 10 can be immobilized in the folded position thanks to an adhesive element.

 On this point, one can use a double-sided adhesive element introduced between the different layers of the support 10, and which thereby plays the role of dielectric.

 Similarly, one can surround the flexible support 10 folded back on itself, using an adhesive tape serving as a sheath for closing. Again, one end of the adhesive tape can be introduced between the different layers of the flexible support 10, so as to serve as a dielectric, as has been previously described.

 According to a third variant, the flexible support 10 can be immobilized in the folded position thanks to a mechanical fixing element. Thus, as shown diagrammatically in FIG. 1, the different layers of the flexible support 10 can be sewn together, with thread 40, on a sewing machine, according to conventional techniques in the matter. As shown in Figure 1, in such a case, it is desirable to carefully arrange the seam between the narrow and conductive strips 20, so as to avoid damaging them.

 Of course, the flexible support 10 can also be immobilized in the folded position using small pliers or staples advantageously replacing the wire 40 as shown in FIG. 1.

 According to yet another embodiment, the folded flexible support 10D can be pinched in a flexible profile of dimensions suitable for this purpose.

 According to a fourth variant, the flexible support 10 can be immobilized, in the folded position, in a sheath or a heat-shrinkable film.

 As shown in FIG. 3, the suppressor electrical connection device according to the present invention proves to be particularly advantageous for connecting two electrical circuits or two printed circuit boards together and being assembled by wave soldering.

 There is thus schematically shown in FIG. 3, in cross section, two printed circuit boards 50 respectively coated with conductive elements 51 to 540 The electrical connection device B is bent over itself lengthwise, and introduced into suitable orifices 55, 56 formed in each of the printed circuits PO, In this position, after wave soldering (57), the narrow electrically conductive strips 20 provide an electrical connection between the elements referenced 52 and 53, disposed respectively on each of the printed circuits 50, while the external shielding 30 provides a connection between the elements 51 and 54 arranged on the printed circuits 50 and which advantageously correspond to the mass of the positive device.

 As has been previously described and shown in FIG. 1, the flexible circuit 10 and the conductive coating 30 forming the shielding are pre-cut so that when the flexible support is folded at least twice on itself, it has two layers 11 and 12 (carrying the strips 20 and half of the covering 303 of substantially equal length, and a third layer 13 (carrying the other half of the covering 30), of shorter length More precisely still, each of the two layers it and 12, previously cited, has at each of its ends engagement edges 11a and 12a, generally oblique, rectilinear or rounded, intended to facilitate the insertion of these layers 11 and 12 into the orifices 55 and 56 of the printed circuits 50 On the other hand, as always appears in the figures, each of said layers 11 and 12 is preferably provided at each of its ends, set back from said engagement edges 11a and 12a, with cutouts llb, 12b, generally rectangular or other, directed opposite each other and opening onto the outer lateral edge of these same layers il and 12. The length separating the cutouts llb and 12b provided at the respective ends 11 and 12 is substantially equal to or greater than the length of the third layer 13.

 The length of the orifices 55 and 56 provided in the printed circuits 50 must be slightly less than the width of the layers II and 12, when the flexible support 10 is folded back on itself, while being slightly greater than the distance separating the cutouts Iib and 12b from the same end of the support.

 Thus, it is easily understood that said layers 11 and 12 are introduced into the orifices 55 and 56, by bending of the fins defined in front of the cutouts llb and 12b, these fins returning, by elasticity, to the initial position, so as to immobilize the connection device 1, as soon as they have passed through the thickness of the printed circuit 50. This thus ensures the immobilization of the connection devices 1 on the circuits 5D before proceeding to wave welding. As shown in the figure i, the third layer 13 having a length less than that of the layers 11 and 12, at each end of the connection device, the narrow conductive strips 20 are accessible on one side, while on the other side, the shielding is accessible 30.

 As illustrated in FIG. 3, this arrangement makes it possible to connect two printed circuit boards 50, by means of an electrical connection device 1, using a solder-wave, being assured that there will not exist not, at the end of the operation, an electrical connection between the shield 30 and the strips 20.

 In fact, in practice, it is found that it is difficult to make, in the printed circuits, cutouts having a width less than 1 mm, while the support has a thickness of the order of 0.08 mm and the conductive strips a thickness of the order of 0.05 mm. Because of the play that therefore exists, it is necessary, If we do not take precautions, during the welding, to carry out checks.

However, one can for example inflate the end of the connection device by a dielectric introduced between the layers of the support to limit such play, or use any other similar means.

 According to another variant, the ends of the device 1 can be folded 90 outwards to be applied flat on the circuits 50 and to be soldered thereon. This avoids the aforementioned drawbacks.

Of course, the connection device 1 could be connected to electronic elements or circuits, by crimping or pinching, or quite simply using a conventional soldering iron.
We will now describe in more detail the embodiments shown in Figures 4 and 5
The embodiments of FIGS. 4a to 5b are represented substantially on scale 1.

 As shown in Figures 4a and 4b, the support 10 has a width of about 27 mm. Over a third of its width! zone A), the support 10 is provided with two electrically conductive bands 20. Over the other two thirds of its width (zones B and C), the support 10 is provided with an electrically conductive coating 30. Of course, the bands 20 and the covering 30 are separated so that they are electrically insulated. Said zones A, B and C correspond respectively to the layers 11, 12 and 1-3 above.

 More specifically, the covering 30 covers the whole of two thirds (zones B and C) of the width of the support 10, that is to say approximately 18 mm while the two strips 20 do not cover the whole of the remaining third (zone A).

 According to the embodiment shown, the strips 20 have a width of about 2 mm and are spaced about 3 mm apart.

 The two zones B and C of the coating 30 are delimited at the level of half the width of the coating by a series of discontinuities 31, of elongated shape, in the metallization. The discontinuities 31 which extend parallel to the strips 20 constitute a line of weakness D intended to facilitate the folding of the support and of the covering.

 As shown in FIGS. 4a and 4b, the outermost zone C of the covering 30 has a length which is approximately 4 mm shorter at each end relative to the adjacent zone B.

 Thus, when the support is folded twice on itself, a first time around the line E common to the area and to the area B, a second time around the line D of the said discontinuities 31, the strips 20 and the covering. 30 are accessible from either side of the device, at each end thereof.

 On the other hand, according to the embodiment shown in Figure 4a, at the ends of the middle zone B, the coating 30 does not cover the entire width of this zone but is in the form of two extensions 32 substantially parallel Such an arrangement aims in particular to facilitate assembly by welding.

 Such a device can easily be immobilized by sewing g40) as shown in FIG. 4b and as previously described, or by any other suitable means.

 However, as shown in FIG. 4a, the support 10 is further provided with discontinuous, equidistant conductive strips 15, parallel to the strips 20, and arranged between them.

The purpose of these m5 bands is to facilitate the positioning of punches capable of cutting out recesses 16 in the support, between the bands 20,
As shown in FIG. Sa. These recesses 16, of generally rectangular or other shape, are thus regularly distributed over the length of the support between the strips 20.

 For the rest, the device 1 represents in Figures Sa and Sb is substantially identical to that shown in Figures 4a and 4b. Thus, it is understood that, thanks to the recesses 16, when the support 10 is folded at least twice on itself, the faces of the zones B and C opposite the coating 30 can be brought into contact through the recesses 16. It is possible to thus weld together, with ultrasound, zones B and C, as shown at 41 in FIG. 5b, to immobilize the support in the folded position.

 The recesses 16 allow two zones (B and C) of the support 10 to be welded together and not three zones (A, B and C), which is difficult with current techniques.

In addition, as shown in FIG. Sa, it is possible to provide, on the lateral zone C of the support 10 and of the covering 30, rectangular or other openings 17 capable of allowing, in the folded position, not to be disposed between the openings 16, only two thicknesses of support (zones
A and B). Again, as previously indicated, this technique facilitates ultrasonic welding at 42.

 Preferably, the device according to the present invention can be stored in the form of a roll in which appropriate lengths of product are cut. Of course, as has been described, it is desirable to reduce in length half (zone C) of the shielding, so as to access both the strips 20 and the coating 30.

 However, when it is essential to have cutouts llb and 12b, it will be preferable to provide rolls of product provided, at predetermined lengths, with cutouts llb and 12b formed beforehand by punching.

 As will be clear to those skilled in the art, the device according to the present invention proves to be simple to use, much easier to prepare than the previously existing devices, since it requires only a simple pair of scissors, and finally much more reliable since the contacts (20) are in no way damaged during preparation.

 Of course, the present invention is not limited to the embodiments which have just been described, but extends to any variant in accordance with its spirit.

 In particular, the expression "flexible support folded back at least twice on itself" should not be understood in a limiting sense, but covers the case where, for example, the flexible support is wound on itself, by. such that the coating constituting a shield substantially surrounds the conductive strips 20.

 On the other hand, the number of electrically conductive strips 20 can be chosen as desired.

Claims (11)

 1. Electrical connection device characterized in that it consists of a support (10) generally planar, flexible and thin, electrically insulating which carries at least one strip (20) narrow, electrically conductive, extending over any its length, as well as an electrically conductive coating (30), separated from said electrically conductive strip (20), also extending substantially over the entire length of the support, and having a width such that when the flexible support (10) is folded back at least twice on itself, substantially parallel to said electrically conductive strip (20), the latter is surrounded by the coating (30) which then constitutes a shield.  2. Device according to claim 1, characterized by the fact that the narrow strip (20) and the coating (30) electrically conductive, are arranged on the same side of the flexible support (10).  3. Device according to one of claims 1 and 2, characterized in that the flexible support (10) is folded at least twice on itself so that the coating (30) constituting a shield is disposed on the outside .  4. Device according to one of claims 1 to 3, characterized in that the flexible support (10) is a thermoplastic resin.  5. Device according to claim 4, characterized in that the flexible support (10) is polyethylene terephthalate.  6. Device according to one of claims 1 to 5, characterized in that each narrow strip (20) and the coating (30) electrically conductive are metallic conductors and preferably copper.  7. Device according to one of claims 1 to 6, characterized in that a dielectric body is inserted between the different layers (11, 12 and 13) of the flexible support (10), when the latter is folded back on itself .  8. Device according to one of claims 4 or 5, characterized in that the flexible support (10) is immobilized in the folded position by ultrasonic welding (Figures Sa and 5b).  9. Device according to one of claims 1 to 7, characterized in that the flexible support (10) is immobilized in the folded position thanks to an adhesive element.  10. Device according to one of claims 1 to 7, characterized in that the flexible support (10) is immobilized in the folded position thanks to a mechanical fixing element (40). (Figures 1, 4a and 4b).  11. Device according to one of claims 1 to 7, characterized in that the flexible support (10) is immobilized in the folded position by insertion into a heat-shrinkable sheath.