Abstract:
The present invention concerns a middle part ( 20, 200 ) of a timepiece case comprising at least one exterior element ( 30 ), said exterior element being secured to the middle part on a securing area by an elastic securing means ( 70 ), characterized in that said middle part further includes at least one aperture ( 26, 206 ) opening onto the securing area at said elastic securing means, enabling the user to act on and deform said elastic securing means and to separate the exterior element ( 30 ) from said middle part.

Description:
[0001]    This application claims priority from European Patent Application No. 12171070.1 filed Jun. 6, 2012, the entire disclosure of which is incorporated herein by reference. 
         [0002]    The present invention concerns a timepiece comprising a middle part closed by a back cover and a crystal, said timepiece further comprising a rotating bezel system secured to said middle part. 
         [0003]    The technical field of the invention is the technical field of fine mechanics. 
       BACKGROUND OF THE INVENTION 
       [0004]    The present invention concerns an exterior element for the middle part of a timepiece case such as a timepiece bezel. 
         [0005]    Exterior elements such as known rotating bezel systems  2 , seen in  FIG. 1 , comprise a rotating bezel  4  taking the form of an annular part. This annular part has a top face and a bottom face, the top face being the face seen by the user. As seen in  FIG. 2 , this bezel  8  has a toothing  10  in the bottom surface thereof. The rotating bezel system further includes a spring means  11 . This spring means  11  is inserted between the rotating bezel and the middle part  3  of timepiece  1 , when bezel  4  is forcibly fitted onto the middle part of the timepiece. This spring means  11  takes the form of a flat ring comprising leaves on the surface thereof facing the toothing in bezel  8 . These leaves are arranged to tilt relative to the plane of the flat ring. The leaves have some elasticity so that the spring means acts on the rotating bezel to exert a vertical force. This vertical force has a tendency to push the bezel off the middle part of the timepiece. 
         [0006]    The leaves also serve to cooperate with the toothing in the bezel. The leaves and toothing are then configured so that the bezel can only rotate in one direction, since the leaves prevent the bezel from rotating if the user attempts to rotate said bezel in the wrong direction. Generally, the bezel and the spring means are made of steel which has the advantage of being durable and inexpensive. 
         [0007]    The bezel is driven onto the middle part  2  of the watch case. To achieve this, the middle part has a peripheral shoulder  2   a  in which said rotating bezel system is placed. The shoulder  2   a  has a wall  2   b  parallel to the central axis (C) of the middle part and a wall perpendicular to the central axis of the middle part. Parallel wall  2   b  of said shoulder has a peripheral groove  2   c.  Bezel  8  is an annular part having a peripheral rim  8   a  on the bottom face thereof. The rim is provided with a continuous addendum  12  extending along said rim towards the axial centre of the bezel. When said rotating bezel system is driven onto the middle part of the watch case, the continuous addendum is inserted into the peripheral groove of the shoulder ensuring that the bezel is held vertically on the middle part. 
         [0008]    One drawback of this system is that it cannot be disassembled. Indeed, the bezel of prior art rotating bezel systems is driven onto the middle part of the case so that any attempt to remove the rotating bezel system generally has to be achieved by pulling the system off, which results in its destruction. 
         [0009]    Naturally, this depends on the material of which the bezel is made. A plastic bezel which is driven onto the middle part will be easier to remove than a steel bezel. This tendency arises from the fact that plastic has elastic properties meaning that it deforms more easily than steel, which means that it is easier to assemble and disassemble a plastic bezel than a steel bezel. 
       SUMMARY OF THE INVENTION 
       [0010]    It is an object of the invention to overcome the drawbacks of the prior art by proposing to provide a middle part including at least one exterior element which is easy to assemble and disassemble. 
         [0011]    The invention therefore concerns a middle part of a timepiece case comprising at least one exterior element, said exterior element being secured to the middle part on a securing area by an elastic securing means, characterized in that said middle part further includes at least one aperture opening onto the securing area at said elastic securing means allowing the user to act on and deform said elastic securing means and to separate the exterior element from said middle part, said securing means comprising a male part which includes at least two hooks, at least one of which is flexible, arranged on one of the faces of said exterior element and a female part arranged on said middle part comprising at least one groove, the male part cooperating elastically with the female part so that the at least two hooks are inserted into the said at least one groove in order to secure said exterior element to said middle part and in that said at least one aperture opens into the female part, allowing the user to act on said at least one flexible hook to separate the exterior element from said middle part. 
         [0012]    A first advantage of this invention is that it provides a middle part comprising at least one exterior element which can easily be separated from said middle part. This means that it is possible to have an exterior element which can easily be changed in the event of a shock or damage or which can easily be removed to facilitate maintenance. 
         [0013]    In a second embodiment, the middle part includes a horizontal wall perpendicular to a central axis of the middle part on which the female part is arranged, the exterior element being arranged on said horizontal wall via the face of said exterior element on which a male part is arranged. 
         [0014]    In a third embodiment, the middle part includes a shoulder formed by said horizontal wall and by a vertical wall parallel to the central axis of the middle part, the exterior element being mounted on said shoulder. 
         [0015]    In a fifth embodiment, each of said hooks includes a strip extending perpendicularly from the face of the exterior element on which the male part is arranged, the free end of said strip having a horizontal protrusion extending perpendicularly to said strip. 
         [0016]    In a sixth embodiment, said male part includes several strips arranged along a circle, and at least two of said strips include a protrusion, said female part comprising at least one groove into which the strips are inserted. 
         [0017]    In another embodiment, said male part includes a first strip and a second strip having a protrusion, the first strip and the second strip being diametrically opposite each other and arranged so that the first strip extends angularly at a first angle and the second strip extends angularly at a second angle, the first angle being smaller than the second angle and so that action on the first strip separates the exterior element from said middle part. 
         [0018]    In another embodiment, the middle part includes a shoulder, formed of a vertical wall parallel to the central axis of the middle part and of a horizontal wall, perpendicular to the central axis of the middle part, on which the female part is arranged, in which the exterior element is arranged. 
         [0019]    In another embodiment, said female part includes a rim extending from the horizontal wall of the middle part in a parallel direction to the central axis of the middle part, the free end of said rim comprising a first protruding portion extending parallel to said horizontal wall towards the central axis of the middle part, said first protruding portion defining a space forming the groove into which said at least one aperture opens. 
         [0020]    In another embodiment, said female part comprises a recess forming the groove, said recess has an inner flank and an outer flank perpendicular to the horizontal wall of the middle part, said outer flank having a second protruding portion extending parallel to said horizontal wall towards the central axis of the middle part, said first protruding portion defining a space into which said male part is inserted, said at least one aperture opening into said space. 
         [0021]    In another embodiment, the first angle extends over around 20°, and the second angle extends over around 120°. 
         [0022]    In another embodiment, the middle part comprises two apertures allowing the user to act more efficiently on said male part to separate the exterior element from the middle part. 
         [0023]    This invention also concerns a timepiece case comprising a middle part, said middle part being closed by a crystal and a back cover, said case further comprising a bezel system, characterized in that said middle part is the middle part according to the invention. 
         [0024]    In an advantageous embodiment, the exterior element of the middle part is said bezel system. 
         [0025]    In another advantageous embodiment, the exterior element of the middle part is the back cover. 
         [0026]    In another advantageous embodiment, the bezel system is a bezel comprising the male part of the securing means. 
         [0027]    In another advantageous embodiment, the bezel system includes a pre-assembly ring secured to a bezel ring, the pre-assembly ring comprising the male part of the securing means, the bezel system further comprising a spring means and notch means. 
         [0028]    The present invention also concerns a timepiece including the case of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0029]    The objects, advantages and features of the middle part according to the present invention will appear more clearly in the following detailed description of at least one embodiment of the invention, given solely by way of non-limiting example and illustrated by the annexed drawings, in which: 
           [0030]      FIG. 1  is a cross-section of a timepiece provided with a bezel system. 
           [0031]      FIG. 2  is a schematic view of a bezel system of the prior art. 
           [0032]      FIGS. 3 to 4  are schematic views of two alternatives of the first embodiment of the bezel system of the invention. 
           [0033]      FIG. 5  is a schematic, bottom view of a preferred variant of the first embodiment of the bezel system of the invention. 
           [0034]      FIGS. 6A and 6B  are schematic views of a second variant of the first embodiment of the bezel system of the invention. 
           [0035]      FIG. 7  is a schematic view of a second embodiment of the bezel system of the invention. 
           [0036]      FIGS. 8 to 11  show schematic views of the steps for separating the bezel from the middle part according to the invention. 
           [0037]      FIG. 12  is a schematic, exploded view of the bezel system according to the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0038]    The present invention proceeds from the general inventive idea which consists in providing an exterior element for the middle part of a timepiece which is easy to disassemble. 
         [0039]    A timepiece case  10  comprises a middle part  20  closed by a back cover  60  and by a crystal  40 . This case  10  further comprises the exterior element  30 . This exterior element  30  is secured to a securing area of the middle part. This exterior element  30  may be a bezel system  80  secured to the middle part. This bezel system  80  takes the form of an annular ring having a top face and a bottom face. Middle part  20  comprises a shoulder  2   a  in which the bezel is placed. This shoulder  2   a  has a vertical wall  21 , i.e. parallel to the central axis (C) of the middle part  20 , and a horizontal wall  22 , i.e. perpendicular to the central axis (C) of middle part  20 . The top face of the annular part is the face seen by the user; the bottom face is the face opposite horizontal wall  22  of the middle part. An exploded view of case  10  is shown in  FIG. 12 . 
         [0040]    Advantageously, the bezel system  80  seen in  FIG. 3  is a bezel  82  secured to middle part  20  so as to be easily removable therefrom. To achieve this, a securing means  70  is arranged on middle part  20  and on exterior element  30 , here bezel  82 , so that it is possible and simple to disassemble said bezel system  80 . 
         [0041]    Securing means  70  includes a male part  71  arranged on bezel  80  and a female part  72  arranged on middle part  20 . Male part  71  is arranged on bezel  82  preferably on bottom face  84 . This male part  71  takes the form of at least two hooks  83  extending from said bottom face  84 , i.e. perpendicularly to the plane of bottom face  84 . Hooks  83  are formed of a strip  86 , which extends in a vertical direction, perpendicular to the plane of bottom face  84  and the free end of which comprises a protrusion  87 . This protrusion  87  extends in a horizontal direction, i.e. parallel to the plane of bottom face  84  or perpendicular to the strip, outwards. This means that protrusion  87  extends in a direction tending to move away from the central axis of the annular part which is bezel  82 . 
         [0042]    Female part  72  is arranged on middle part  20  and, in this first embodiment, takes the form of grooves  23 ,  203  in which a hook  83  of bezel  82  is inserted. The number of grooves  23 ,  203  is at least equal to the number of hooks  83  arranged on bezel  82 . This groove  23 ,  203  is arranged so that, when hook  83  is totally engaged therein, protrusion  87  of said hook  83  prevents the bezel from being separated from middle part  20 . It is clear that at least two hooks  83  are necessary to secure bezel  82 . 
         [0043]    In a first alternative of female part  70  of middle part  20  seen in  FIG. 3 , the hook takes the form of a rim  24  located on horizontal wall  22  of the shoulder. This rim  24  extends perpendicularly to horizontal wall  22  of the shoulder and is peripheral. This peripheral rim  24  has an inner face and an outer face  24   a.  The outer face, the farthest from the central axis (C) of middle part  20  includes, at the free end of rim  24 , a protruding portion  25  parallel to horizontal wall  22 . This protruding portion  25  forms an open space  27  between said protruding portion  25  and horizontal wall  22  of shoulder  2   a.  This space is used for inserting protrusion  87  of hook  83  therein. 
         [0044]    In a second alternative of female part  70  of middle part  200  seen in  FIG. 4 , female part  70  includes a recess  203   a  forming a groove  203  located on the horizontal wall  202  of shoulder  2   a.  This groove  203  has an inner flank and an outer flank  204 . A protruding portion  205  extends from outer flank  204 , the farthest from central axis (C) of middle part  20 , forming an open space  207  between said protruding portion  205  and horizontal wall  202  of shoulder  2   a.  This space  207  is used for inserting protrusion  87  of hook  83  therein when hook  83  is inserted into groove  203 . 
         [0045]    During assembly, bezel  82  is placed in the shoulder so that each hook  83  is placed opposite a groove  23 ,  203 . When pressure is exerted on bezel  82  to secure it to bezel  20 ,  200 , hooks  83  tend to be elastically deformed to enter grooves  23 ,  203 . When protrusion  87  of each hook  83  is opposite space  27 ,  207  between said protruding portion  25 ,  205  and horizontal wall  22 ,  202  of the shoulder, hooks  83  return to their rest position and the protrusion  87  of each hook  83  enters said space  27 ,  207 . The cooperation between hooks  83  and the space between said protruding portion  25 ,  205  and horizontal wall  22 ,  202  provides axial retention. Protrusion  87  provides a locking surface which abuts on protruding portion  25 ,  205  and locks bezel  82  if the user pulls on said bezel. Thus, for two hooks  83  located on the bezel, middle part  20 ,  200  includes two grooves  23 ,  203 , said hooks  83  and grooves  23 ,  203  being arranged such that bezel  82  is correctly positioned, i.e the screen printed time indications on the bezel are properly positioned relative to the dial. 
         [0046]    Cleverly, according to the invention, exterior element  30 , i.e. bezel  82 , can easily be disassembled. To achieve this, middle part  20 ,  200  comprises at least one aperture  26 ,  206  opening onto the securing area, i.e. on the female part. It is clear that said at least one aperture  26   206  opens into space  27 ,  207  present between said protruding portion  25 ,  205  and the horizontal wall  22 ,  202  of the shoulder. This aperture  26 ,  206  is dimensioned so that the user can slide a tool  90  therein which may be a blade or a tip as seen in  FIGS. 8 to 11 . Tool  90  is inserted into said aperture  26 ,  206  so as to create pressure on protrusion  87  which holds said bezel  82  secured to middle part  20 ,  200 , as seen in  FIGS. 8 to 11 . Thus, when the user slides tool  90  into aperture  26 ,  206  until it comes into contact with said protrusion  87 , he exerts pressure on protrusion  87  via tool  90  so that hook  83  is deformed and protrusion  87  of said hook leaves space  27 ,  207  between said protrusion  25 ,  205  and horizontal wall  22 ,  202  of the shoulder as seen in  FIG. 10 . It then becomes possible for the user to raise the bezel to remove one of hooks  83  from groove  23 ,  203 , as seen in  FIG. 11 . The user can then manipulate bezel  83  to release the other hook  83  from groove  23 ,  203  with which it cooperates. 
         [0047]    Preferably, middle part  20 ,  200  comprises two apertures  26 ,  206  arranged so that a tool  90  with two tips can be used. Indeed, if hook  83  has a large width, exerting force at only one point means there is a risk of said hook  83  only being deformed at the place where pressure is exerted. The force exerted is thus liable to be insufficient to cause protrusion  87  to be released from space  27 ,  207  between said protrusion  25 ,  205  and horizontal wall  22 ,  202  of the shoulder. Having a part configured with two tips means that the forces exerted by the tool are better distributed on protrusion  87  and therefore hook  83 . This means that there are two contact points with protrusion  87  and thus said hook  83  is elastically deformed more efficiently. 
         [0048]    In a first variant of this first embodiment, the male part  71  of securing means  70  includes several strips  86  arranged in a virtual circle  86   a  as seen in  FIG. 5 . Male part  71  is arranged so that some strips  86  have a protrusion  87  extending in a direction which tends to move away from the centre of virtual circle  86   a.  Female part  72  located on middle part  20 ,  200  takes the form of a groove  23 ,  203  forming a circle identical to virtual circle  86   a.  This groove  23 ,  203  may be arranged to follow the principle of the first version or of the second version of the hooking system. Male part  71  of bezel  82  may then cooperate with female part  72  of middle part  20 ,  200 . This configuration also simplifies assembly since bezel  82  can be assembled without any specific orientation with respect to middle part  20 ,  200 . The advantage of this configuration is that it allows bezel  82  to rotate with respect to the middle part, with the male part moving along the groove which acts like a rail here. Toothing means and spring means are thus arranged on the middle part for controlling the rotation of the bezel. 
         [0049]    Another advantage is that the male part may also have strips  86  which do not have a protrusion  87 . These strips  86  are used for radial retention. 
         [0050]    Advantageously, this variant, seen in  FIG. 5 , is configured so that male part  71  comprises two strips  86  having a protrusion  87 . Strips  86  are preferably diametrically opposite each other; a first strip  88  extends angularly at a first angle al of around 20°, whereas the second strip  89  extends at an angle α2, greater than the first angle, of around 120°. This particular configuration provides improved axial retention. In fact, the axial retention of bezel  82  on middle part  20 ,  200  is achieved by the protrusions  87  of hooks  83  which cooperate with groove  23 ,  203 , as explained above. If both strips  86  extended angularly over a small angle, axial retention would be provided but there would be a risk that strong traction on bezel  82  could remove it from middle part  20  and  200  and damage said bezel. Indeed, the traction force would be applied over a small surface area causing high stress on strips  86  with protrusion  87  and thus a significant risk of breakage. With the proposed configuration, axial retention is improved since male part  71  has a larger locking surface. Consequently, the stress exerted during traction is distributed over a larger surface area and less stress is applied to protrusions  87 . 
         [0051]    Moreover, this configuration is achieved such that first strip  86 , which extends angularly over a small angle is the strip operated by the user to release bezel  82  from middle part  20 ,  200 . Indeed, when the user wishes to release bezel  82  from middle part  20 ,  200 , he acts on bezel  82  so that first strip  86  moves opposite the at least one aperture  26 ,  206  opening into space  27 ,  207  between said protruding portion  25 ,  205  and horizontal wall  22 ,  202  of the shoulder. This allows the user to use his tool  90  to act on first strip  86  and thus to release bezel  82  from middle part  20 ,  200 . The fact that there are two strips  86  with a protrusion  87  disposed diametrically opposite each other and that one of the strips extends over a larger angle than the other provides a bezel  82  which is properly retained on middle part  20 ,  200 , yet which can easily be separated therefrom. However, the strip which extends over a larger angle must not exceed a certain angle. 
         [0052]    In a second variant of this first embodiment bezel system  800 , seen in  FIGS. 6   a  and  6   b , is formed of several elements. It is thus clear that bezel system  800  comprises a pre-assembly ring  812  having a bottom face  812   b  and a top face  812   a.  Spring means  810 , toothing means  811  and a bezel ring  809  are arranged on the top face  812   a  of pre-assembly ring  812 . Bezel ring  809  is the part seen by the user. Spring means  810  and toothing means  811  are arranged so that spring means  810  is angularly integral with middle part  20 ,  200 , toothing means  811  being angularly integral with pre-assembly ring  812  and bezel ring  809 . Spring means  810  may be angularly integral with pre-assembly ring  812  and with bezel ring  809 , with toothing means  811  being angularly integral with middle part  20 ,  200 . Male part  71  of securing means  70  is arranged on top face  812   b  of pre-assembly ring  812 . This variant has the advantage of providing a bezel system  800  in the form of an independent module which can be fixed to middle part  20 ,  200  or separated from middle part  20 ,  200  as a single unit. 
         [0053]    In a second embodiment visible in  FIG. 7 , exterior element  30  is the back cover  60  secured to middle part  2000 . Indeed, it may be useful to have a removable back cover  60  both in a mechanical timepiece and an electronic timepiece. This possibility of having a removable back cover  60  provides easy access to the watch movement. It is therefore easy to maintain the movement, replace parts or change the battery. 
         [0054]    Middle part  2000  comprises a bottom face to which said back cover  60  is secured. Preferably, middle part  2000  and back cover  60  have a substantially similar shape for aesthetic reasons. The bottom face of middle part  2000  includes the female part  72  of securing means  70  for cooperating with male part  71 , arranged on back cover  60 . 
         [0055]    The bottom face of the middle part could also have a similar shoulder to that described for the first embodiment. The exterior element takes the form here of a cover which closes the middle part. The features of the first embodiment and the variants and versions thereof may be applied to this second embodiment. 
         [0056]    The sealing of this exterior element arranged as the back cover of the middle part may be improved by inserting a sealing gasket in said exterior element. 
         [0057]    It will be clear that various alterations and/or improvements and/or combinations evident to those skilled in the art may be made to the various embodiments of the invention set out above without departing from the scope of the invention defined by the annexed claims.