Abstract:
A zipper closure including first and second rows of teeth formed on first and second bands. Each tooth has a free end in which a channel is formed. Each channel has a bottom which is convexly curved. The zipper closure includes a slider with a projection for opening and closing the zipper closure.

Description:
BACKGROUND OF THE INVENTION 
     The invention concerns a zipper closure (fastener) having teeth made of a plastic material which are formed on two strips. Free ends of the teeth in one row extend into a fixing region of the other row of teeth, and the free ends are provided with channels. 
     A known zipper closure is described in German laid-open application (DE-OS) No 23 04 341. Since successive teeth of the zipper closure overlap practically over their entire lengths, it is relatively difficult to open the zipper closure. In order to exert an opening force onto a critical region of the zipper closure during opening of the zipper closure, it has already been suggested to provide bands of the zipper closure with a second bead or web on which the outer surface of a slider slides along. The bands are pulled apart due to the widening of the slider between its back end and its front end. 
     SUMMARY OF THE INVENTION 
     The aim of the present invention is to exert a force in an opening direction during opening onto teeth of a zipper closure of the kind set forth in the opening part of this specification by virtue of the configuration of a slider. The slider of the zipper closure is provided with a tapered projection which is arranged at the height of channels in the teeth. The tapered projection projects beyond a cross-piece which connects a top cover plate to a bottom cover plate of the slider. The channels have bottoms which are convexly curved in the plane of the teeth. 
     Therefore, the core of the invention lies in the combination of two features. One feature is that a projection, which is disposed at the height of the channels, must be arranged on the slider. Another feature is that the channels must extend towards a vertical centerline of the zipper closure to such an extent that the base of the channels moves behind a separating line when the teeth are inclined in the slider. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Detail of the invention are explained with reference to the accompanying drawings. 
     FIG. 1 is a top or elevation view of a zipper closure; 
     FIG. 2 is an enlarged longitudinal sectional view through a tooth; 
     FIG. 3 is an enlarged top view of two adjacent teeth; 
     FIG. 4 is an enlarged vertical longitudinal sectional view through a slider; 
     FIG. 5 is an enlarged top view of the zipper closure in which bands and a cover plate of the slider have been removed; and 
     FIG. 6 corresponds to FIG. 2 for a second embodiment. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A zipper closure is shown in FIG. 1. The zipper closure comprises two bands 5, 5&#39;, on which teeth 1, 1&#39; are arranged. Edge beads (webs) 9, 9&#39; of the bands 5, 5&#39; serve to support teeth 1, 1&#39;, and the teeth 1, 1&#39; are attached to the beads 9, 9&#39; by injection molding during production thereof. Decorative stones 3, for example made of lead crystal, are embedded at the same time. A slider 4 is used to open and close the zipper closure in the usual way. 
     As can be seen from FIGS. 2 and 3, contact areas of the teeth 1, 1&#39; confronting and abutting one another in the closed position are designed to have a prismatic shape such that the contact areas encounter no resistance to a vertical shifting of the teeth relative to one another (i.e., shifting in a direction perpendicular to the plane of FIG. 3), aside from friction. The teeth 1, 1&#39; are anchored normal with respect to the bands 5, 5&#39;. Channels (grooves) 6, 6&#39; formed in free ends of the teeth 1, 1&#39; receive the beads 9, 9&#39; of the opposing band 5, 5&#39;. So that this is possible, the teeth 1, 1&#39; must have a length which approximately corresponds to the width of the closed zipper closure. Viewed from above each tooth 1, 1&#39; starting from a base 11, 11&#39; converges to a narrowest area or portion thereof, from which support surfaces 2, 2&#39; extend outwardly nearly parallel to the bands 5, 5&#39;. The free end of each tooth 1, 1&#39; has approximately a half ellipse shape. 
     Decorative stones 3 can be arranged in a straight line. Spacing between the stones 3 is small in comparison with the sizes of the stones 3, if the support surfaces 2, 2&#34; are kept correspondingly small. The support surfaces 2, 2&#34; are kept small by the acute angling thereof relative to the direction of the teeth 1, 1&#39;. In the illustrated embodiment, the length h of each support surface in a strip direction is approximately a third of the diameter D of the jewelry stones 3. This arrangement allows each jewelery stone 3 to be adequately surrounded by plastic material while nonetheless the spacing between successive stones 3 is small. 
     The slider 4 is shown in a longitudinal sectional view in FIG. 4, and comprises top and bottom cover plates 12 and 13. Both side walls of the slider 4 respectively have upper and lower parts 14 and 15, which are divided by slits along their full lengths. The bands 5, 5&#39; run through the slits, and the beads 9, 9&#39; are supported by the inner surfaces of the upper and lower parts 14 and 15 of the side walls. A cross-piece 20 connects the top cover plate 12 to the bottom cover plate 13. 
     In order to exert a force on the teeth 1, 1&#39; in an outward direction when opening the zipper closure, the crosspiece 20 is provided with a projection 10, which has a lance tip shape. The projection 10 extends beyond the end of the cross-piece 20 and is directed toward a narrow end of the slider 4. During opening of the zipper closure, this projection 10 engages the channels 6, 6&#39; of the teeth 1, 1&#39; and presses them into tracks lying on both sides of the cross-piece 20, which extend toward a wide end of the slider 4. 
     As shown in FIG. 5, bottoms 16 of the channels 6 provided at the free end of the teeth 1, 1&#39; are curved between opposite sides of the teeth 1, 1&#39; that face other teeth 1, 1&#39;. This arrangement allows the projection 10 to be guided into the channels 6 and it prevents the projection 10 from colliding with vertical outside walls of the teeth 1, 1&#39;. 
     The invention makes it possible to produce zipper closures having very large teeth which are very decorative by virtue of the correspondingly large stone surfaces. Stones 3 must be securely embedded in plastic material with a minimum spacing from the grooves 6. A proportional increase in the size of the stone 3, as shown in FIG. 5, quickly causes the stone 3 to reach a minimum spacing limit. More specifically, the market does not want thick zipper closures because they make articles of clothing fitted therewith stiff and cause the clothing to lift away from the wearer. In order to remedy these disadvantages, flat stones 3 are used in conjunction with large teeth 1, 1&#39;. The rear surfaces of the stones 3 converge to a point at an angle of at least 120°. Further, the rear surfaces of the stones 3 are coated with a reflective metal coating. The use of such stones results in the zipper closure being a flat structure, as shown in FIG. 6.