Patent Publication Number: US-6658707-B2

Title: Folding clasp for interchangeable watch strap

Description:
FIELD OF THE INVENTION 
     The present invention relates to a folding clasp for an interchangeable watch strap and more particularly for a flexible watch strap of leather, synthetic material, textile or the like. 
     BACKGROUND OF THE INVENTION 
     There exist watch straps which are provided with means permitting the user to change the strap himself without a tool. Thus, the user can secure to a watch case a metallic strap or a leather strap or any other type. In the case of leather straps, these latter are provided with buckles or folding clasps, but in this latter case each leather strap must necessarily be provided with such a clasp. This increases the price of the straps, particularly for items in precious metal because, in this case, the folding clasps must also be of precious metal. 
     OBJECT OF THE INVENTION 
     The object of the present invention is to give the user the possibility of himself removing, without a tool, the folding clasp of an interchangeable flexible strap, to install it on another flexible strap, for example of a different color or texture. Thus, a single folding clasp is necessary, no matter what the number of interchangeable straps the user possesses. 
     The interchangeable strap can for example be of the type described in European patent No. EP 1128237 A1 (European patent application No. 00103952.8 of Feb. 25, 2000 in the name of the applicant). It is however evident that the present invention is applicable equally to any other type of interchangeable strap that can be removably secured, even without a tool, on the watch case. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings show schematically and by way of example a particular embodiment of the folding clasp for an interchangeable watch strap according to the invention. 
     FIG. 1 is a fragmentary plan view of a watch strap provided with a folding clasp according to the invention, the clasp being in the closed condition. 
     FIG. 2 is a cross-section on the line A—A of FIG.  1 . 
     FIG. 3 is a perspective view of the folding clasp mounted on a strap, the clasp being in the closed condition. 
     FIG. 4 is a plan view from above of the folding clasp alone, in the open position. 
     FIG. 5 is a plan view from below of the folding clasp alone, in the open position, certain parts being seen in cross-section. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The folding clasp according to the invention is designed so as to be able to be assembled to the tongues of an interchangeable watch strap. This mounting is designed such that the user can apply and remove the clasp to and from the tongues of the strap without a tool, rapidly and very easily. Thus, a same clasp can serve several interchangeable straps, which is very advantageous particularly when the clasp is of precious metal. Moreover, this mounting ensures the possibility of easily adjusting the length of the strap. Finally, as will be seen later, the assembly and disassembly of the tongues of the strap on the clasp requires only a manipulation of the ends of the tongues of the strap, but no mechanical intervention on the clasp itself. 
     Conventionally, each tongue of the strap comprises a passage or hole at its end to be connected to the clasp. A screw passes through this hole and is screwed into an end of the clasp. To assemble and disassemble each tongue of the strap, a screwdriver is needed. Moreover, after several manipulations, the screw may no longer keep screwed in or blocked with sufficient force to avoid it unscrewing under the influence of oscillating movement of the tongues of the strap. The strap can thus untimely come apart from the clasp, which can lead to the loss of the watch and strap. This drawback is not present in the folding clasp according to the invention. The folding clasp shown comprises two arms articulated on each other at one of their ends. Of course, the folding clasp according to the invention could comprise three portions articulated on each other. 
     The illustrated folding clasp comprises a first arm  1  whose one end terminates in a finger  2  and a second arm  3  whose one end terminates in a fork  4 . These arms  1 ,  3  are held together by an axle  5  passing through the two ends of the fork  4  and the end of the finger  2  located between the ends of said fork. The two arms  1 ,  3  are thus articulated on each other at one of their ends. 
     The free end of the arm  1  comprises on the one hand an opening  6  adapted to coact with a lug  7  on the other end of the arm  3  of the clasp. This lug  7  and this opening  6  permit snap-in retention of the two arms in the folded and closed position of the clasp. 
     The free end of the arm  1  comprises a securement device for a tongue of the strap, comprised by a guide  8  having in cross-section a general U shape, an axle  9  formed by a screw or a pin connecting the opposite wings of the guide  8 , and holding members formed by the tongues  10  bent toward each other and secured to the wings of the guide and extending in the direction of the longitudinal axis of the clasp. 
     The user can thus introduce the end of a strap tongue  11  between the axle  9  and the tongues  10  of the guide  8  that extend toward each other, he then reverses the end of this tongue  11  by 180° and threads it between the axle  9  and the dorsal portion of the U-shaped guide  8 . The length of the strap can be adjusted by defining the length of the reverse portion of the tongue  11 . The tongue  11  of the strap is thus held in its position coupled to the clasp by the axle  9 , the dorsal portion of the guide  8 , and the tongues  10  extending toward each other. 
     The free end of the other arm  3  is articulated by means of a screw  12  on the lateral portions  13  of the cover  14  of the clasp. An axle  15  connects the two lateral portions  13  of the cover  14 . The upper portion of the cover  14  comprises retaining members  16  for the strap, extending in the direction of the tongue  17  of the strap. 
     The user threads the end of the tongue  17  of the strap between the retaining members  16  of the cover, bends it about the axle  15  by 180° to secure this tongue  17  on the cover of the clasp. 
     As will be seen from the drawings, the ends of the tongues  11  and  17  of the strap are made thin such that once folded in two, they have a thickness substantially equal to the thickness of the strap itself. 
     The strap of course comprises at its two ends before being secured to the watch case, quick securement systems that do not need a tool, for example of the type described in European patent application No. 00103952.8. 
     Thus, the user can change the strap as he wishes, the interchangeable coupling on the watch case being guaranteed by said rapid securement system that requires no tool, and can thus adapt the new leather strap to a clasp as described in the present application. The user can retain his watch and his clasp, which can for example be of precious metal, and can himself change the strap easily and rapidly without a tool. 
     This clasp also has the advantage that the two tongues of the strap may be identical, which simplifies and rationalizes the production of the straps. 
     Finally, thanks to the fact that the adjustment of the length of the strap takes place over the two tongues of the strap, the user can always adjust the strap such that the clasp will be centered on his wrist, always located opposite the watch.