Abstract:
Disclosed is a woven strap, particularly for safety belts in motor vehicles, which is characterized in that said woven strap comprises a first group of warp threads and a second group of warp threads, the warp threads of the first group being provided with a greater elongation than the warp threads of the second group.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of PCT patent application serial no. PCT/EP2004/010752, filed on Sep. 24, 2004, which claims priority to German patent application serial no. 103 44 334.7, filed on Sep. 24, 2003, both of which are incorporated by reference herein. 
    
    
     BACKGROUND AND SUMMARY 
     The invention relates to a woven webbing, particularly for automotive seat belts. 
     Woven webbing, also for use in automotive seat belts, is known from a wealth of publications and practical examples. In certain cases items are attached to one or more points of the webbing, whereby depending on how the items are attached this could result in the material of the webbing being weakened, thus resulting in the specified tensile strength of the webbing possibly no longer being satisfied over the full width in the scope as demanded. Such items are, for instance, retainer buttons for preventing movement, for example of a buckle, beyond the point of attachment. In addition, there are, for example, also microphones for automotive hands-off telephone systems which are attached to seat belts at one or more points. It is in this arrangement that the attachment damages threads, particularly warp threads, of the webbing to such an extent that the tensile strength of the webbing is reduced. 
     An object of the invention is to propose a woven webbing, particularly for automotive seat belts which is suitable for the attachment of applications in the run of the woven webbing, as well as such seat belt themselves in avoiding or at least greatly reducing the disadvantages known from prior art. This object is achieved with a woven webbing as it reads from claim  1 . The first group of warp threads having a higher extensibility is provided to advantage in a portion in which application items are to be attached. Because of the higher extensibility of the corresponding warp threads any weakening and thus reduction in the tensile strength of the warp threads caused by the application items is now compensated such that both groups of warp threads feature the necessary tensile strength when the webbing is stressed. In this arrangement, the difference in the extensibility of the warp threads of the first group and the warp threads of the second group is selected to advantage so that when exposed to tensile stress all threads counter the tensile force uniformly. If, for instance, laser welding an application item, e.g. a microphone, to the woven webbing in accordance with the invention results in a weakening of the warp threads of the first group, this weakening now has no effect on proper functioning of the woven webbing, since the selected high extensibility of the warp threads of the first group compensates any weakening of the tensile strength. 
     In one advantageous further embodiment of the invention the woven webbing comprises warp threads of a third group comprising electrically conductive means. This now makes it possible to power electric devices attached at some location to the woven webbing in the sense of the warp threads of the first group; these electric devices may be, for example, microphones, sensors, controllers, and the like. In another advantageous further embodiment of the invention the warp threads of the first group comprise electrically conductive means in thus endowing the warp threads having a higher extensibility with a second function, namely the conduction of electricity. This combination of enhanced extensibility and conduction of electricity simplifies the structure of the woven webbing in accordance with the invention as a whole. In yet another advantageous further embodiment of the invention the electrically conductive means are electrically insulated at their surface. Now, the electrically conductive means can be routed very close together because of the individual insulation of the warp threads instead of having to rely on insulation due to a spacing even with electrically conductive warp threads spaced as viewed in the weft direction. It has been discovered to advantage that varnish coating the electrically conductive means can now be produced very cost-effectively and reliably in even attaining a color-matched varnish coating. 
     In a particularly advantageous further embodiment of the invention the woven webbing is configured so that the electrically conductive means are wound by the warp threads. This design of the warp threads wound with electrically conductive means has major advantages, especially in contraction and/or stretching of the woven webbing. The electrically conductive means spirally wound around the warp threads in accordance with the invention, for example, conducting wire with a rectangular cross-section complies with the lengthwise movements of the warp threads in their longitudinal direction without themselves being exposed to any appreciable tensile strength possibly tearing the electrically conductive means out of place. The pitch in the windings can be advantageously tailored to the particularly application concerned. 
     In one advantageous alternative in configuring the electrically conductive means arranged at the warp threads of the first group or third group it is now attained that a finely curled wire is arranged as the electrically conductive means within warp threads forming a staple common fiber. This design of the electrically conductive means also permits compensating contraction and/or stretching without ruining the electrically conductivity. In still another advantageous further embodiment the warp threads comprising electrically conductive means are “concealed” so-to-speak in the interior of the woven webbing. This has the major advantage that the electrically conductive means are now no longer visible whilst, on the other hand, being protected from wear and corrosion. In one additional advantageous further embodiment of the woven webbing in accordance with the invention one or more electrically device(s), especially microphone(s), sensor(s), controller(s) is/are applied to one or more locations in the region of the warp threads. This now makes it possible to apply an electrical device expediently for the application concerned at any location in the longitudinal run of the woven webbing; for example, a microphone for a hands-off telephone system, for a telephone or dictaphone, or a device for monitoring the health of the vehicle occupant such as pulse, temperature etc., or a lighting fixture or a loudspeaker. Further advantages and features read from the sub-claims. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       For a better appreciation of the invention it will now be detailed by way of an example with reference to the drawings in which: 
         FIG. 1  is a plan view of a woven webbing in accordance with the invention shown simplified diagrammatically and on a greatly magnified scale. 
         FIG. 2  is the same view of the woven webbing as shown in  FIG. 1 , showing warp threads but with a microphone attached. 
         FIG. 3  is a view of a warp thread wound with a electrically conductive means on a greatly magnified scale. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to  FIG. 1  there is illustrated in a view simplified diagrammatically a webbing  10  having a width B, warp threads  2  of a certain extensibility running over the outer portions—in a number which as shown has merely been selected to be symbolic—whereas in the middle portion, selected in this case just as an example, warp threads  1  of greater extensibility than the warp threads  2  run. The very short portion of a webbing  10  in accordance with the invention shown in  FIG. 1  has in this case a very broad middle portion, selected just as an example, in which warp threads  1  having a higher extensibility run. It will be appreciated that this illustration is shown exaggerated for the sake of clarity. In reality, such a webbing contains hundreds of warp threads over the width B of the webbing very much finer than the warp threads  1  and warp threads  2  as shown in  FIG. 1 . Merely for orientation of a device to be applied thereto is a circle identified by the reference numeral  5  shown in the middle of the webbing  10 , this being, of course, just a qualitative indication. 
     Referring now to  FIG. 2  there is illustrated the webbing  10  as already shown in  FIG. 1 , now, however, a microphone  5  being symbolically evident in the middle in the region of the warp threads  1  of high extensibility. The microphone  5  is connected via warp threads  6  belonging to the group of warp threads  1  but incorporating electrically conductive means  4 . Shown as an example are two warp threads  6  having the same extensibility as the warp threads  1  but additionally provided with electrically conductive means  4 , details of which are given in the following. As an alternative the microphone  5  shown as an example in  FIG. 2  can be powered via warp threads  3  shown additionally inserted between the warp threads  1 . This is intended to indicate how the warp threads  3  may likewise include electrically conductive means—not highlighted in this case—but not necessarily having cross-sections and parameters other than those of warp threads  1 . 
     Referring now to  FIG. 3  there is illustrated on a greatly magnified scale a warp thread  3  or  6 , the latter belonging to the group of warp threads  1 . The structure of the warp thread as shown in  FIG. 3  as a short discontinued portion is illustrated just as a qualitative indication. A warp thread core  8  is provided with a rectangular cross-section—see the diagrammatic illustration to the left of the warp threads  6 ,  3  in FIG.  3 —the core  8  possibly being made of PET, for example, whereas the electrically conductive means  4  is selected from a favorable electrically conductive alloy. 
     In an additional advantage aspect as shown in  FIG. 3  on the left the electrically conductive means  4  is provided with an insulation  9  consisting of varnish, for example. Here too, the dimensions are roughly drawn merely qualitatively. The windings of the electrically conductive means  4 , as shown in  FIG. 3 , have a pitch S, resulting in a spacing a between the individual windings in conjunction with the width of the electrically conductive means  4  configured as a band. Depending on whether the webbing in accordance with the invention is extended or contracted as intended after or during weaving, a larger pitch S is selected when contracted, a smaller pitch S when extended resulting in the spacing a being set so that no buckling or rupture of the electrically conductive means  4  can materialize. 
     In viewing the FIGs. as described above, the person skilled in the art will, of course, immediately appreciate that the weft threads of the webbing  10  in accordance with the invention are not shown for the sake of a better overview. But, of course, in reality the actual appearance of a webbing is often such that the warp threads determine the appearance of a webbing, since the weft threads usually are not at all evident. Contrary to how they are shown in  FIG. 2 , the warp threads with the electrically conductive means illustrated diagrammatically therein are actually embodied concealed in the interior of the webbing so that they are, for one thing, concealed from view and, for another, are protected from damage from without. In the example aspect as described in this case, warp threads  2  in each case are shown with electrically conductive means. In reality, however, considerably more such warp threads may be provided depending on the nature and quantity of the electrical signals to be conducted. 
     The conductors achieved by the warp threads with electrically conductive means are thus brought out to the surface as desired only in defined regions for electrically connecting the corresponding electrical devices, for example, to which, for instance, by means of laser welding a cap or housing of an electrical device, for example of a microphone, can be applied. However, as already emphasized repeatedly, configuring the woven webbing in accordance with the invention achieves a uniform tensile strength of the warp threads over the width of the finished webbing. It is also to be noted that it is possible to apply a device to the surface of the webbing in accordance with the invention not just on one side but on both sides. 
     The automotive seat belt in accordance with the invention with the electrically conductive warp threads included in the weave is suitable moreover with the application of the corresponding devices for monitoring medical data of a vehicle occupant such as, for example, pulse, blood pressure, temperature, etc. Apart from this, it is of advantage for out-of-position-technology since it permits sensing the current position or posture of a vehicle occupant as to physique, weight, etc and even in tailoring the development of an air bag in the vehicle interior to the current situation in case of a collision. 
     Yet another possibility is an additional function with the webbing in accordance with the invention in namely checking its proper functioning so as to, for example, signal the need for replacement/renewal in due time due to wear and tear.