EP1261069A1 - Traction strain relief device - Google Patents

Abstract

The device has first and second holding elements (11,13) movable between open and holding positions and lockable in the holding position with a section of flat conductor between them. A region of the flat cable's foil (16) with no conductors or only edges of conductors is clamped between a protrusion (22a) on the first element and a recess (26) in the second to provide strain relief. AN Independent claim is also included for a plug connector with an inventive device.

Description

The present invention relates to a strain relief device for flexible Flat conductor.

There are usually strain relief devices in connectors provided that serve one with contact elements in the connector connected conductor to the housing of the connector attach so that there is a pull on the conductor from the housing of the connector and thereby a mechanical load the contact elements with possible loss of contact is avoided. According to the state of the art, strain relief for connectors takes place for flexible flat conductors in that there are holes in the flexible flat conductors be punched through the corresponding tenon one with the flexible Connect flat conductor connected connector, so that on the flexible flat conductors exerted tensile forces over the edges of the punched holes be transferred to the pin in the connector housing.

However, this type of strain relief has the disadvantage that in an additional Work corresponding holes in the flexible flat conductor to be punched.

In addition, there is a risk that the flexible at high tensile load Flat conductor through the pins of the strain relief device which reach into its holes or the connector torn and thus is damaged so that it must be replaced as a whole.

The disadvantages mentioned exist for all types of flexible flat conductors, especially for FPC flat conductors (flexible printed circuits) or FFC flat conductors (flexible flat circuits).

In addition, it often makes sense to make strain relief devices independent of connectors to withstand tensile loads for long To catch ladders. When using the described strain relief according to the prior art, the same disadvantages also occur here.

It is an object of the present invention to provide a strain relief device for a flexible flat conductor, especially an FPCoder FFC flat conductor, provide a strain relief when used of the flat conductor is achieved without additional work steps and the risk of tearing under high tensile loads is greatly reduced becomes.

The problem is solved by a strain relief device with the Features of claim 1.

A strain relief device according to the invention is for strain relief a given flexible flat conductor provided therein, the has a carrier film and therein a given distribution of conductor tracks. The flexible flat conductor can in particular be FPC and / or FFC flat conductors, which among other things Decide that the thickness of the conductor tracks is essential for FPC flat conductors is lower than with FFC flat conductors.

The strain relief device has a first holding element and second holding element, which for fastening a flat conductor between an open position for inserting the flat conductor and a holding position are movable and can be locked against each other in the holding position, a section of the flexible flat conductor between the two holding elements can be included. The holding elements can be in the open position already connected or as two separate, there are elements to be merged. Furthermore, for Locking appropriate devices, for example snap elements, be provided, but not necessarily on the holding elements themselves must be attached.

For strain relief, a projection and are on the first holding element a corresponding depression is formed on the second holding element, that when enclosing the flexible flat conductor between the first and the second holding element and when the same moves into the holding position and mutual locking an area of the carrier film that does not Has conductor tracks or only edge areas of conductor tracks, for strain relief pressable from the projection into the recess and at the other Edge can be clamped. The holding elements are at or after the connection with the flexible flat conductor to exercise the necessary Clamping force locked against each other or connected to each other, for what Devices corresponding to the holding elements for locking or Connection can be provided. Because jamming in non-conductive Areas or only marginal areas of conductor tracks As a rule, the lead does not extend across the entire width of the flexible Extend flat conductor.

The projection on the first holding element and the corresponding one Depth on the second holding element depending on the Thickness of the carrier film of the flexible flat conductor must be dimensioned such that a corresponding clamping effect occurs at the edge. As a result of that possibly only marginal areas of conductor tracks at the edge of the depression be pinched and this usually from a relative easily deformable metal such as Copper exists, plays for the Clamping effect essentially only the thickness of the carrier film an essential Roll, while the thickness of the conductor tracks is irrelevant.

By pinching at the edge of the depression is comparatively small clamping area a high clamping pressure and therefore one good strain relief achieved, moreover by the thickness of the conductor tracks is largely independent. The invention is therefore suitable Strain relief devices especially for flexible flat conductors, the carrier foils of the same thickness but different conductor tracks Have thickness, especially for FPC and FFC flat conductors.

The friction between can make an additional contribution to strain relief the projection and the carrier film lying against it arise.

Because the strain relief alone by moving the first and the second Holding element with inserted flat conductor in the holding position and locking or joining is achieved, to train the strain relief no additional work steps necessary, so a very simple but reliable assembly is possible.

In addition, there is a risk of tearing under high tensile loads greatly reduced because tensile forces over the entire edge of the depression which the film is pinched.

The strain relief devices according to the invention are also made of plastic, e.g. by injection molding, very simple and inexpensive produced.

Further developments and preferred embodiments of the invention are characterized in the description, the drawing and the subclaims.

Preferably, the projection and the recess are formed so that the Carrier film of the flexible flat conductor when it is clamped by the Edge of the recess is scored. The notch is created here by plastic deformation of the carrier foil of the flat conductor, which is usually made of plastic or plastic laminates containing e.g. polyester or polyimides. By engaging the edge of the recess in the notch, the strain relief of the invention Strain relief device absorb particularly high tensile forces.

The edge of the depression is preferred for a particularly good clamping effect edge-shaped, the angle, that is enclosed by the surfaces forming the edge, about 90 ° is. Due to the edge-shaped design of the edge, the pinching takes place over a comparatively small area, which means that not only the particularly good clamping effect is effected, but also the training a notch-like deformation in the carrier film is favored. In addition, there is a particularly effective form fit between the edge-shaped edge and the notch-like deformation the carrier film.

However, the projection and the recess should preferably be designed in this way be that when the flexible flat conductor is pinched, its carrier film only is scored and / or stretched, the stretch being a act at least partially irreversible deformation of the carrier film can. However, the projection and the recess should preferably not be so be designed such that when the flat conductor is pinched, holes or cracks arise in the carrier film, which e.g. if the gap between Projection and edge of the recess or a tapered tip Lead could occur. This will result in tensile loads less easily damage in the carrier film.

The projection is preferably dome-shaped, so that damage the carrier foil of the flexible flat conductor is largely excluded is. With such a shape, the carrier film can be one inserted flexible flat conductor also over a large area on the projection concern, which makes an additional contribution to strain relief achieved by the friction between the projection and the adjacent carrier film becomes.

Furthermore, the projection can preferably be in the form of a truncated cone be, with particular preference the truncated cone on its narrow, free end has strongly rounded edges. Through the Tapering the truncated cone becomes a particularly good clamping effect achieved at the edge of the recess, even if the thickness of the carrier film is around their mean fluctuates more.

Are preferred in the direction of an expected train, i.e. usually in the direction of the longitudinal extension of the flat conductor, in each case at least three projections and three corresponding depressions are provided. there it is not necessary for all the projections to be formed on the first holding element, rather, individual projections can also be on the second holding element and the corresponding depressions are formed in the first holding element his. As a result, the strain relief by the invention Strain relief device absorb higher tensile forces because the forces be distributed over three marginal areas. In addition, the protrusions also absorb torques, so that not too wide Flat conductors also secure against twisting the flat conductor in the Strain relief device is achieved.

Furthermore, one is expected to be essentially transverse to the direction Zuges preferably at least two projections and corresponding Provided recesses in the holding elements, again here not all protrusions in the first holding element and all depressions in the second holding element must be arranged. By this arrangement the protrusions and recesses will rotate a flexible one Flat conductor in the strain relief device even when the width of the Avoided flat conductor.

Since the strain relief in a strain relief device according to the invention takes place over areas of the carrier film that do not have a conductor track or only have edge regions of conductor tracks, the distance is preferred between the first and the second holding element in the area of Inclusion of the flexible flat conductor except on the projection larger than the thickness of the flexible flat conductor, i.e. including the carrier film of the conductor tracks. Such a strain relief device can therefore also the same for other flexible flat conductors with a carrier film Thickness, but different conductor thickness can be used.

Also preferred is a device for fastening the strain relief device, provided in particular on a body. in this connection it can be an adhesive strip or parts of a Velcro fastener. However, fastening openings can also be made, for example, for rivet, Screw or snap fasteners may be provided. Furthermore can use snap elements on the strain relief device come. In particular detachable connections, for example screw, Velcro and some snap fastenings allow easy later disassembly of the flat conductor together with the strain relief.

Another object of the invention is a strain relief device with a flexible flat conductor held with it, in particular one FPC and / or FFC flat conductor, the strain relief device according to one of the above-mentioned embodiments or a combination of which can be formed.

Another object of the invention is a connector with an inventive Strain relief device, in particular according to the preferred Embodiments.

A connector according to the invention, which is a plug or a coupling can act is for attachment to a given flexible flat conductor provided.

The connection of contact elements provided in the connector with conductor tracks of the flexible flat conductor can be carried out by conventional methods such as. Crimping process, pressure contacting or soldering respectively.

In the connector according to the invention, the strain relief device can in particular be connected to its housing, so that strain relief device and housing made of plastic, e.g. by injection molding, are very easy and inexpensive to manufacture.

In a preferred embodiment, the connector has two that can be joined together and interconnectable housing parts, between which a flat conductor can be included. One of the housing parts then has one of the holding elements, the locking of the holding elements against each other together with the connection of the housing parts he follows. Appropriate locking devices on the housing parts are in this context as part of the strain relief device to watch. By assembling and connecting the housing parts Inserting a flat conductor, which is simultaneously a movement of the holding parts in the holding position and a mutual locking effect can thus The connector housing and the strain relief are manufactured in one step be effected.

Fig. 1

eine schematische Schnittansicht eines Steckverbinders mit flexiblen Flachleiter nach einer ersten bevorzugten Ausführungsform der Erfindung

Fig. 2

eine teilweise, schematische Schnittansicht durch den Steckverbinder mit flexiblem Flachleiter in Fig. 1 entlang der Linie A-A und

Fig. 3

eine schematische perspektivische Ansicht einer Zugentlastungsvorrichtung mit flexiblem Flachleiter nach einer zweiten bevorzugten Ausführungsform der Erfindung.

Preferred embodiments of the invention are described below by way of example with reference to the drawings. Show it:

Fig. 1

is a schematic sectional view of a connector with flexible flat conductor according to a first preferred embodiment of the invention

Fig. 2

a partial, schematic sectional view through the connector with flexible flat conductor in Fig. 1 along the line AA and

Fig. 3

is a schematic perspective view of a strain relief device with flexible flat conductor according to a second preferred embodiment of the invention.

Fig. 1 shows schematically a connector according to a preferred Embodiment of the invention with a first housing part 10 and a second housing part 12. The first housing part 10 and the second housing part 12 are assembled and close an FPC flat conductor 14 between them. The housing parts are in the area of the flat conductor as holding elements 11 and 13 (schematically in the drawing by dashed lines Lines indicated) trained.

The FPC flat conductor 14 comprises a carrier film 16 with two enclosed therein Copper traces 18a and 18b. The carrier film 16 is here only shown schematically. It is made of at least in a manner known per se two plastic films laminated on top of each other the copper conductor tracks 18a and 18b are known to enclose. As can be seen in FIG. 1, the FPC flat conductor 14 therefore has in the areas which have the copper conductor tracks 18a and 18b, a larger one Thickness than in the areas without traces. It arises in the area of the edge of the copper conductor tracks 18a and 18b is a continuous one Transition from the large thickness in the area of the copper conductor to the reduced thickness in the areas without conductor track.

The holding element integrated into the first housing part 10 on its underside 11 has a recess 20, the width of which is just the width of the FPC flat conductor 14 and which are in the direction of the flat conductor, as seen in Fig. 2 extends. In the middle of the recess 20 are formed three projections 22a, 22b and 22c in the direction of Conductor 18a and 18b of the FPC flat conductor 14 between the copper conductor tracks 18a and 18b are arranged.

The holding element 13 integrated in the second housing part 12 also has a recess 24, the width and length of the Recess 20 in the first housing part 10 corresponds. In the middle this recess 24 three recesses are formed, which are arranged are that the projections 22a, 22b and 22c when assembled of the first and the second housing part and thus the movement of the Holding elements 11 and 13 engage in their holding position in these depressions can. In Fig. 1 is only the corresponding in the projection 22a Well 26 visible. The edges of the depression are edge-shaped, the two surfaces forming the edges forming an angle of Include 90 °. The recess is still so deep that at assembled first housing part 10 and second housing part 12, i.e. when the holding elements 11 and 13 are in their holding position, the Projections 22a, 22b and 22c with the carrier film arranged underneath 16 do not touch the bottom of the recess.

The protrusions 22a, 22b and 22c and the corresponding depressions are shaped so that the FPC flat conductor 14 between the projection and the edges is pinched. As in FIG. 1 using the example of the depression 26 recognizable, the edge 28 notches the carrier film 16, whereby it becomes one additional positive locking between the edge and the carrier film 16 comes, which allows that of the holding elements 11 and 13 and thus higher tensile forces can be absorbed by the connector. The As can be seen in FIG. 2, projections 22a, 22b and 22c have one circular cross-section and are dome-shaped in the direction of second housing part arched. On the one hand, this ensures that when clamping the FPC flat conductor 14, the carrier film 16 does not perforate or is torn. On the other hand, the carrier film 16 lies flat on the projections 22a, 22b and 22c, so that by the friction between the corresponding areas of the protrusions 22a, 22b and 22c and the carrier film 16 creates an additional strain-relieving effect.

As can be seen in FIG. 1, the FPC flat conductor 14 is only in one area, that has no copper traces from the protrusions 22a, 22b and 22c are pressed into the corresponding depressions and at the edges thereof trapped. The other areas of the FPC flat conductor 14, in particular the areas with the copper conductor tracks 18a and 18b are also located loose in the space formed by the recesses 20 and 24. It other flexible flat conductors, e.g. FFC flat conductor with the same thickness of the carrier foil but greater thickness of the copper conductor tracks, can be used with the same connector because of the Recess 20 and 24 formed space in the area of the holding elements 11 and 13 of the strain relief device also enough space for the areas an FFC flat conductor with thicker copper conductor tracks and for others the clamping effect and thus strain relief only in areas the carrier film is achieved without conductor tracks.

The housing parts 10 and 12 with the integrated holding elements 11 and 13 can be inexpensively injection molded from plastic become. They do not have to, as in this embodiment, as Full body, but can still contain cavities, as far as sufficient stability is guaranteed.

For assembly, the FPC flat conductor 14 is first inserted into the recess 24 of the second lower housing part 12 inserted. Then the first housing part positioned above the second housing part, the two housing parts 10 and 12 are compressed and by one in the figures device not shown connected together. By squeezing the carrier film 16 in the region of the projections 22a, 22b and 22c on the one hand somewhat stretched, which is shown in the schematic diagrams 1 and 2 is not shown, and on the other hand to the Edges of the depressions to form a notch, a carrier film 16 pinched. The forces necessary for clamping are thereby by the device for connection and not shown in the figures Locking of the two housing parts added. Because of the partial irreversible expansion leads to the formation of cup-shaped bulges in the carrier film in the area of the projection.

Fig. 3 shows a strain relief device according to a second preferred Embodiment with a first holding element 30 and a second Holding element 32 in an open position with an inserted FPC flat conductor 34 with conductor tracks 38a and 38b.

The strain relief device is made in one piece from a sufficiently rigid Plastic formed, the holding members 30 and 32 on one first narrow side to the side of the FPC flat conductor in an open position with each other are connected. The holding elements are in the FPC flat conductor facing areas as well as the holding elements 11 and 13 in the first embodiment.

To lock the holding elements 30 and 32 in the holding position are on the second narrow side of the first holding element 30 on the end face 40 a web 42 and on the second narrow side of the second holding element 32 a resilient bracket 46 is provided on the end face 44, which over the Web 42 snaps when the second holding element 32 against the first holding element 34 is pressed.

There is a through hole for fastening the strain relief device 48 provided that a fastening, for example on a body part made possible by means of screws or rivets.

LIST OF REFERENCE NUMBERS

10

first housing part

11

first holding element

12

second housing part

13

second holding element

14

FPC flat conductor

16

support film

18a, 18b

Copper traces

20

recess

22a, 22b, 22c

head Start

24

recess

26

deepening

28

edge

30

first holding element

32

second holding element

34

FPC flat conductor

36

support film

38a, 38b

Copper traces

40

face

42

web

44

face

46

hanger

48

Through opening

Claims (14)

Strain relief device for a flexible flat conductor (14; 34), which has a carrier film (16; 36) and given distribution of conductor tracks (18a, 18b; 38a, 38b) therein, in particular FPC and / or FFC flat conductors, with a first holding element (11; 30) and a second holding element (13; 32), which are movable between an open position for inserting the flat conductor and a holding position and can be locked against one another in the holding position, a portion of the flexible flat conductor (14; 34) between the two Holding elements is included, and
in which a projection (22a, 22b, 22c) on the first holding element (11; 30) and a corresponding recess (26) on the second holding element (13; 32) are formed such that when the flexible flat conductor (14; 34 ) between the first and the second holding element (11, 13; 30, 32) and upon movement of the same into the holding position and mutual locking, an area of the carrier film (16; 36) which does not have any conductor tracks or only edge areas of conductor tracks (18a, 18b; 38a, 38b), can be pressed from the projection (22) into the recess (26) for strain relief and can be clamped at the edge (28) thereof. Strain relief device according to claim 1,
characterized in that the projection (22) and the recess (26) are formed such that when the flexible flat conductor (14; 34) is clamped in, the carrier film (16; 36) of the flexible flat conductor through the edge (28) of the recess (26) is scored. Strain relief device according to claim 1 or 2,
characterized in that the edge (28) of the recess (26) is edge-shaped. Strain relief device according to one of the preceding claims,
characterized in that the projection (22) and the depression (26) are designed such that when the flexible flat conductor (14; 34) is clamped in, the carrier film (16; 36) is only notched and / or stretched, but not holes or cracks arise in the carrier film. Strain relief device according to one of the preceding claims,
characterized in that the projection (22) is dome-shaped. Strain relief device according to one of claims 1 to 4,
characterized in that the projection (22) has the shape of a truncated cone. Strain relief device according to one of the preceding claims,
characterized in that at least three projections (22a, 22b, 22c) and three corresponding depressions (26) are provided in the direction of a train to be expected. Strain relief device according to one of the preceding claims,
characterized in that at least two projections (22a, 22b, 22c) and corresponding depressions (26) are provided in the first and the second holding element (11, 13; 30, 32) substantially transversely to the pulling direction. Strain relief device according to one of the preceding claims,
characterized in that the distance between the first and the second holding element (11, 13; 30, 32) in the area (20, 24) for receiving the flexible flat conductor (14; 34) except at the projection (22a, 22b, 22c) is greater than the thickness of the carrier film (16; 36) including the conductor tracks (18a, 18b; 38a, 38b). Strain relief device according to one of the preceding claims,
characterized in that a device (48) is provided for fastening the strain relief device, in particular to a body. Strain relief device according to one of the preceding claims with a flexible flat conductor (14; 34) held with it, especially an FPC or FFC flat conductor Strain relief device according to claim 11
characterized in that the flexible flat conductor (14; 34) has a carrier film (16; 36) and a given distribution of conductor tracks (18a, 18b; 38a, 38b) therein,
that the first holding element (11; 30) and the second holding element (13; 32) are in the holding position and are locked against one another, a section of the flexible flat conductor (14; 34) being enclosed between the two holding elements, and
that the flexible flat conductor (14; 34) enclosed between the first and second holding element in the holding position (11, 13; 30, 32) in a region which has no conductor tracks or only edge regions of conductor tracks (18a, 18b; 38a, 38b), for strain relief from the projection (22) pressed into the recess (26) and clamped on the edge (28). Connector with a strain relief device according to a of claims 1 to 12. Connector according to claim 13,
characterized in that the plug connector has two housing parts (10, 12) which can be joined and connected to one another, between which a flat conductor (14) can be enclosed and each of which has one of the holding elements (11, 13), and
that the locking of the holding elements (11, 13) against each other takes place together with the connection of the housing parts (10, 12).

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