Abstract:
Control device for a watch movement having a part rotatably movable around an axis A. The device is associated with a watch case ( 11 ) and has a lock ( 25 ) actuatable from outside the watch. The lock is movably mounted in translation to the periphery of the watch case ( 11 ). The device also has a movably mounted plate ( 30 ) which is rotatable around an axis D inside the watch case and is kinematically connected to the lock. An arm ( 34 ) is pivotable around and axis B, whose first end is placed on the plate in such a way that it is freely rotatable around an axis C non-merging with the axis D and whose other end is fixed to the part for driving the movement.

Description:
TECHNICAL FIELD 
   The present invention relates to horology. More specifically, it concerns a control device of the type designed to actuate, from the outside of its case, a mechanism of a watch movement. 
   BACKGROUND 
   Certain mechanisms, such as that known to those skilled in the art as a “minute repeater”, are generally actuated by a rotational movement of a component provided with a toothed sector that is caused to pivot directly by a circular sliding of a push-piece in the middle of the watch case. 
   One problem with this construction is that it can only be used on a round case because the path of the push-piece is necessarily circular, otherwise the connection with the component with the toothed sector cannot be direct. 
   One of the objects of the invention is to make it possible to actuate a mechanism of this kind by the translational movement of a push-piece along a curve close to a straight line rather than by a circular sliding action. The path of this translational movement has an infinite radius of curvature when applied to a rectangular case, but it may also have a radius of curvature of typically more than two times the width of the case, when applied to a so called tonneau case. 
   SUMMARY OF THE INVENTION 
   More precisely, the invention relates to a watch mechanism control device comprising a component rotatable about an axis A. The device is designed to be fitted to a watch case and comprises a push-piece actuatable from the outside of the case. 
   According to the invention, the push-piece can be moved translationally along the periphery of the case and the device includes, housed in the watch case:
         a plate mounted, rotatably about an axis D, inside the case, and connected kinematically to said push-piece, and   an arm hinged about an axis B, with one end arranged over the plate and free to rotate about an axis C that does not coincide with axis D, and the other end fixed to the component for actuating the mechanism.       

   The push-piece occupies a first extreme position when it is at rest. Advantageously it is acted upon by an elastic member for moving it to and keeping it in this first position. The elastic member may be a spring acting on a rod connected detachably to the push-piece. 
   The rod ends in a cam designed to act on a pin located on the plate. 
   There is also a second problem with the prior-art devices. Since the movement of the push-piece in the case is of about 25°, it is very difficult to seal the connection between the movement and the push-piece around so large a sector, while allowing the control device to move. 
   A second object of the invention is to provide a sealed push-piece type control device. 
   For this purpose, in the device provided above, the rod slides within a housing formed by a separate component attached to the watch case. This separate component is a strip that comprises, in the vicinity of one of its ends, a housing through which the rod passes and in which an O ring is to be placed. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other details will become clearer on reading the description which follows, which refers to the accompanying drawing, in which: 
       FIGS. 1   a  and  1   b  are top views of the mechanism in its first and second extreme positions,  FIG. 1   a  also including an enlarged view of a detail, and 
       FIG. 2  is a view of the back of the watch case incorporating this device. 
   

   DETAILED DESCRIPTION 
   The figures show a barrel-shaped casing ring  10  designed to sit in a tonneau watch case  11  whose middle  12  is of the same shape. The casing ring  10  contains a housing  13  for a watch movement (not shown) and its external outline matches the shape of the inside of the case. As an example, the movement may comprise a minute repeating mechanism in which the striking work is triggered by a toothed sector rotating about an arbor A. The drawing shows only the projections of the mechanism&#39;s various arbors which are perpendicular to the plane defined by the case  11 . 
   The control device according to the invention sits in a space  14  provided in a corner of the casing ring  10  and extends along the side  16  adjacent to this corner, which is in a space designed to be between the two halves of the wristband. 
   A housing is provided longitudinally along the outside edge of the side  16 . It may for example take the form of a separate component  18  welded to the middle  12  across the entire area of contact between these two parts. This component  18  consists of a strip whose ends  19 ,  20  are bent out and meet the edge of the case  11 . 
   End  19  is provided with a hole (not visible in the drawing) and with an annular housing  22  whose purpose will be explained later. 
   A rod  24  slides within the housing and passes through the hole in end  19 . This rod  24  comprises two parts: part  24   a  is that nearest the space  14 , and part  24   b  is of a greater diameter. The two parts are similar in length and form, at their junction, a stop positioned in about the middle of the rod. The diameter of part  24   a  and that of the openings of the component  18  are an exact fit. 
   Part  24   b  of the rod is connected detachably to a push-piece  25  designed to project from the watch case. The case has an opening to allow the push-piece  25  to move on its periphery. A cam  26  located in space  14  is fixed to the end of part  24   a  of the rod. The shape of the cam  26  will be described in detail later. 
   A return spring  27  is mounted on the part  24   a  of the rod. At one end it bears on the stop formed at the junction with part  24   b  and at the other on the end  19 . Consequently, when the push-piece  25  is actuated, the rod  24  moves translationally in the housing, parallel to the edge of the casing ring  10 , compressing the spring  27  in the process, and is returned to its rest position by the spring  27  when the push-piece is released and the spring  27  relaxes. 
   The space  14  continues into an opening  28  situated on the dial side, in which there sits a plate  30  pivoting about an arbor D on the casing ring  10 . The thicknesses of the back of the opening  28  and of the plate  30  are such as to ensure that the cam  26  is situated in a plane higher than the plane of the plate  30 . 
   The plate  30  is provided with a pin  32  at its periphery, in the plane of the cam  26 . The device also includes an arm  34  hinged at an elbow of axis B. One end of the arm  34  is arranged over said plate and is free to rotate about an axis C which does not coincide with axis D. Axis C is preferably situated at the periphery of the plate  30 . The second end of the arm  34  is fixed to the toothed sector of the minute repeating mechanism in order to actuate it. 
   The dimensions of the hinged arm  34  and of the plate  30  are such that the toothed sector of the minute repeating mechanism pivots through an angle of approximately 25° about axis A. 
   Thus, for example, the part of the arm  34  mounted on the plate is 7.2 mm long and that fixed to the toothed sector actuating the minute repeating mechanism is 7.8 mm long. Meanwhile the plate  30  has a diameter of 9.4 mm. Axis C is approximately diametrically opposite the pin  32 . The length of the first part of the above arm  34  is less than the diameter of the plate  30 , so a notch  40  is formed in the periphery of the latter to allow the second part of the arm, which is in the thickness of the plate  30 , not to collide with the latter. 
   To assemble the above mechanism in the case  11 , the rod  24  is placed in the housing formed by the component  18 . The casing ring  10  and the movement are then installed in the case  11  and the push-piece  25  is connected to the rod  24 . Finally, as is routine for those skilled in the art, the case is sealed shut, on one side by the glass and on the other by the back of the case  11 . Similarly, the winding stem is assembled in a sealed manner. 
   More specifically, to fit the back, a seal  42  (visible in  FIG. 2 ) is conventionally laid in a groove formed around the inside perimeter of the case  11 . The presence of this seal  42  means that the only opening not yet sealed between the movement and the outside of the watch is around the rod  24 , more precisely at the point where it passes through the openings of the component  18 . 
   As shown particularly in the enlarged view in  FIG. 1   a , the shape of the component  18  described above means that it is possible to insert an O ring  44  in the housing  22  for the part  24   a  of the rod to pass through. This part  24   a  can slide freely because the O ring  44  is kept in position between the two walls of the housing  22 . 
   Thus, when the case back is fitted, the conventional sealing systems (glass, winding stem and back) combined with the O ring  44  fitted around the rod  24  completely isolate the movement from external influences. 
   At rest, as  FIG. 1A  shows, the push-piece  25  and the rod  24  are pushed by the spring  27  to a first extreme position. The cam  26  is resting on the outside of end  19  of the component  18 , which acts as a stop. More specifically, the cam  26  is in the shape of a right-angled trapezoid. The pin  32  rests on the angle formed between the long base and the oblique side of the cam  26 . The arm  34  is held in this position by the striking barrel of the minute repeating mechanism to which they are connected via the pivot about axis A. 
   When the person wearing the watch wishes to operate the minute repeating mechanism, he or she pushes the push-piece  25  to move the rod  24  along the inside of the track. The cam  26  pushes against the pin  32 , which slides along its long base, turning the plate  30  counterclockwise. Axis B moves around the perimeter of the plate, C moves to the position shown in  FIG. 1   b , and A pivots upon itself, turning the rack of the minute repeating mechanism and thereby winding the striking barrel and triggering the mechanism. The device is now in its second extreme position. 
   As has been seen above, the rod  24  and the push-piece  25  are returned automatically to their rest position by the spring  27 . The arm  34  and the plate  30  are moved back to their first rest position at the same time as the repeating mechanism, the striking barrel of which also returns to the rest position. 
   The invention thus provides a control device for a circularly actuated mechanism that fits a non-round watch case and yet keeps it leaktight.