Patent Publication Number: US-2023140150-A1

Title: Insert for a watch wristlet

Description:
CROSS REFERENCE RELATED TO APPLICATION 
     This application claims priority to European Patent Application No. 21206404.2 filed Nov. 4, 2021, the entire contents of which are incorporated herein by reference. 
     TECHNICAL FIELD OF THE INVENTION 
     The present invention relates to a device for fastening wristlet strands on a watch case allowing to mount and dismount said wristlet strands on the case without tools. 
     TECHNOLOGICAL BACKGROUND 
     The document U.S. Pat. No. 2,850,783 describes a watch wristlet comprising extensible metal strands which are each provided, at one of their ends, with a system comprising a housing extending transversely to the longitudinal direction of the wristlet strand and provided with a transverse opening. The housing is intended to receive a wristlet fastening strip extending between the inner faces of the horns of a watch case. The housing is equipped with a flap that can be moved between a locked position wherein it closes the transverse opening of the housing and thus ensures that the strip is held in the housing and thereby even fastens the wristlet strand to the case and an unlocked position wherein the flap is disengaged from the transverse opening and which allows the wearer of the watch to release the strip from the housing and thus separate the wristlet strand from the case. The flap is locked using tabs bent at 90° which are integral with the shutter and which ensure locking by friction on a rigid edge of the housing. The friction forces involved are relatively low given their small width and the small thickness of the edge against which they bear. Furthermore, after a few locking-unlocking cycles, these tabs are likely to deform plastically and therefore no longer ensure reliable notching or even in the worst case are likely to break and possibly lead to a fall or a loss of the watch. It will also be noted that this system includes three folded sheet metal portions which are quite complex, which makes the system difficult and expensive to produce. 
     SUMMARY OF THE INVENTION 
     The main purpose of the present invention is to provide a device for fastening wristlet strands to a watch case allowing to assemble and disassemble said wristlet strands on the case without tools. 
     The present invention also aims at providing a wristwatch wherein the wristlet strands are provided with a device allowing the manual locking and unlocking of the connection between the strips of the watch case and the wristlet strands of the watch, said system being simple and easy to produce, while guaranteeing secure locking. 
     Another object of the present invention is to provide an insert that can be integrated into a wristlet strand, said insert allowing the wristlet strand to be assembled and disassembled from a strip of a watch case without tools. 
     This purpose is achieved by an insert, a wristlet strand and a watch according to the appended claims. 
     The invention relates to an insert for a strand of a watch wristlet, allowing to manually lock and unlock the connection between the strand and a strip of a watch case, said insert comprises a body made of rigid material and a latch, the body made of rigid material comprising a parallelepiped portion extended by a hook-shaped portion terminating in an edge, said hook-shaped portion forming a housing for the strip, the housing comprising a transverse opening, the parallelepiped portion being configured to be secured to one end of the strand, the latch being housed in a cavity of the body and hinged to the body to cause it to pivot around a hinge axis parallel to the housing, said latch comprising a closing wall capable of closing said housing. According to the invention, the latch comprises locking means formed by a pin integral with the latch cooperating with a hole in the body as well as first return means arranged to constrain the pin in the hole in a locking position, and wherein the latch has a length less than the length of the cavity so that when the latch is pushed manually in the direction of the hinge axis so as to release the pin in an unlocked position wherein the latch is free to pivot around its hinge axis and allows to clear the transverse opening of the housing. 
     In accordance with other advantageous variants of the invention:
         the insert comprises second return means arranged to hold the latch in the unlocked position;   the latch comprises a portion with a reduced thickness so as to form a rim, and the cavity comprises two side walls, one of which has a lower height so as to be partially covered by the latch;   the side wall with a lower height has a slope to limit the angular stroke of the latch relative to the body of the insert;   the latch has a structured upper surface facilitating the locking and unlocking of the latch by a wearer;   the rigid material body is a one-piece element;   the insert is made of metal, of composite material, of ceramic or of plastic material;   the latch comprises a rear portion pierced with a longitudinal through-hole to receive the axis;   the latch comprises a housing of circular section, coaxial with the hole, arranged to receive the first return means;   the housing has a diameter greater than the diameter of the hole;   the second return means are in the form of a torsion spring;   the torsion spring is disposed in a machining of the latch around the axis.       

     The invention also relates to a watch wristlet strand and a watch including a wristlet provided with an insert in accordance with the invention. 
     Other features and advantages of the present invention will appear in the following description of preferred embodiments, presented by way of non-limiting example with reference to the appended drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       Other features and advantages of the present invention will appear more clearly upon reading the detailed description of a preferred embodiment which follows, made with reference to the appended drawings given by way of non-limiting examples and wherein: 
         FIG.  1   a  and  1   b    show an insert in accordance with the invention in its unlocked and locked position; 
         FIG.  2    is an exploded view showing in detail the components of the insert of  FIGS.  1   a    and  1   b;    
         FIG.  3   a    illustrates a bottom view of the latch an insert in accordance with the invention; 
         FIG.  3   b    shows a sectional view of the figure along the axis A-A; 
         FIG.  4    illustrates an insert in accordance with the invention fitted on a wristlet strand. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The insert shown in  FIGS.  1   a  and  1   b    is formed by a body  2  of rigid material which comprises a parallelepiped portion  3  extended by a hook-shaped end portion  4  which defines a housing  5  intended to receive a strip of a watch case (not shown). The housing  5  extends transversely to the longitudinal direction of the wristlet strand and is provided with a transverse opening  5   a.    
     The rigid material body  2  is preferably a uniform part formed from a single material. The body  2  can be made of a metal material or an alloy, a composite material, a ceramic material or else a plastic material. 
     The parallelepiped portion  3  comprises shoulders  6  which allow to provide good hold or a good grip of the insert  1  to the wristlet strand which is generally over-moulded or glued. For example, the insert can be over-moulded with a synthetic material from which the wristlet strand is formed. Alternatively, the insert can be inserted and glued between two layers of a material from which the strand is formed. 
     The insert  1  illustrated in  FIG.  1    is capable of being inserted into a leather strand  100 . The insert can nevertheless easily be adapted to other types and materials (ceramic, rubber, metal, etc.) of strands. 
     As illustrated in  FIG.  2   , it is observed that on the parallelepiped portion  3  of the rigid body  2 , a cavity  30  of rectangular shape with two side walls  31 ,  32  has been machined so as to receive a latch  12 . The latch  12  is hinged in rotation around an axis  8  perpendicular to the longitudinal direction of the wristlet, each of the side walls having a hole  33 ,  34  to receive the axis of rotation. The latch  12  is arranged to rest in the cavity  30  in a position called locking position, and can be moved within this cavity to position it in the open or unlocked position. 
     The latch  12  is a part made, preferably, of metal, for example steel, aluminium, gold, or other metal material. It is pivotally mounted about an axis  8  parallel to the housing  5  and which is inserted or driven into the holes  33 ,  34  of the side walls of the cavity  30 . The latch  12  has a length slightly less than that of the cavity  30  so as to be able to move it in translation within the cavity  30 . 
     The latch  12  comprises a rear portion  13  pierced with a longitudinal hole  14  to receive the axis  8  and whose length is less than the space between the side walls  31 ,  32 . The rear portion  13  of the latch also has a housing  130  for receiving return means such as a compression spring  10  cooperating with one of the side walls  31  of the cavity  30 . The housing  130  is coaxial with the longitudinal hole  14  and has a diameter greater than the diameter of the hole  14  so that the spring  10  remains constrained between the wall  31  and the bottom of the housing  130 . As illustrated in  FIG.  3   b   , the housing  130  extends over half the length of the latch  12 . Obviously, the length of this housing  130  may vary depending on the spring used. 
     The latch  12  further comprises a closing wall  16  having a flat face extending along the longitudinal direction of the housing  5  and resting against the rim  5   a  of the housing, so as to produce a closed housing of section substantially circular when the latch  12  is in the closed position. The latch  12  also comprises locking means and return means arranged to hold the latch in the closed or open position. In the example illustrated, the locking means are formed by a pin  11  integral with the latch  12  and cooperating with an orifice  37  formed in one of the side walls  32  of the space  30 . The return means are in the form a torsion spring  9  disposed on the axis  8 , the rear portion  13  of the latch  12  having a machining revealing the axis and being arranged to receive the spring  9 . As can be seen in  FIG.  3   a   , the latch  12  also has a notch  18  provided to receive a leg of the torsion spring  9 . 
     Advantageously, the latch  12  has at the wall opposite the locking means  11 , a portion with a reduced thickness so as to form a rim  19  resting on the side wall  31  opposite the side wall  32  cooperating with the locking means  11  and which has for this purpose a lower height so that the rim  19  can rest thereon. 
     The side wall  31  also has a portion with a slope  35  so that the latch  12  can pivot around its axis  8  without being blocked by the body  2  when it is unlocked. This slope  35  also allows to act as a stop by defining and limiting the angular stroke of the latch  12  relative to the body  2  of the insert  1 . 
     The side wall  32  in turn has a cutout  36  with a slope to guide the locking means  11  to the hole  37  when the latch moves from the unlocked position to the locked position. Thus, when the wearer presses the latch  12  towards the bottom of the cavity  30 , the pin  11  contacts the slope and causes a translation of the latch  12  in the direction of the axis  8  and implicitly a compression of the spring  8  until the pin  11  is inserted into the hole  37 . Once the pin  11  is housed in the hole  37 , the latch returns to its rest position in the cavity  30  under the action of the spring  8 . 
     The latch  12  also acts as a handling element and has on its upper face, that is to say the face visible to the wearer when the latch is in the closed position, shallow machining or textures in negative or positive relief to facilitate the handling of the latch  12 . 
     In the closed or locked position ( FIG.  1   b   ), the pin  11  integral with the latch  12  is inserted into the hole  37  so as to hold the latch in place in the cavity  30 , the torsion spring  9  being forced between the bottom of the cavity and the latch. The pin  11  is held in the inserted position thanks to the spring  10  which tends to push the latch  12  towards the side wall  32 . 
     To switch the latch  12  to its open or unlocked position ( FIG.  1   a   ), the wearer exerts pressure on the latch  12  and causes it to translate, in a direction perpendicular to the direction of the length of the wristlet strand, until the latter abuts against the side wall  31  of the cavity  30 . This translation has the effect of releasing the pin  11  from the hole  37 , and therefore of allowing the torsion spring  9  to pivot the latch  12  towards its unlocked or open position, thus freeing the passage  5  to assemble or disassemble the wristlet strand. 
     To open the tab, the user will push the tab  16  backwards until the edge  17  is disengaged from the notch  22 , and then switch the latch  12  towards its open position. As shown in section in  FIGS.  4   a   - 4   c,  the part of the edge  17  of the hook-shaped portion  4  which fits into the notch  22  is preferably pointed, having in this way a shape which corresponds to the internal shape of the notch  22 . Other shapes of notches and corresponding edges can nevertheless be considered.