Patent Publication Number: US-7708458-B2

Title: Watch with a striking work

Description:
This application claims priority from European Patent Application No. 06121237.9, filed Sep. 26, 2006, the entire disclosure of which is incorporated herein by reference. 
   FIELD OF THE INVENTION 
   The present invention relates to the field of watchmaking. It concerns more specifically a watch with a striking work, such as a repeater watch or an alarm watch. 
   BACKGROUND OF THE INVENTION 
   Such watches are fitted with an element that vibrates via the action of a hammer, and thus produces, directly or indirectly, an acoustic wave, via another part. The vibrating element may be a bell, a gong or an element of the type disclosed in EP Patent No. 0 400 205. The bell is voluminous and solid. The same is true of the element disclosed in EP Patent No. 0400 205, formed of a solid rigid crown, mounted on a flexible securing element including two arms, the ends of which are secured to a support. The gong, which is small and compact, is generally preferred. The gong is generally formed of a metal strand of circular cross-section, or of a metal strip, forming a winding whose length is variable depending upon the desired tonality. Secured to the bottom plate via one of its ends, the gong transmits vibrations to the bottom plate, which itself can emit an acoustic wave. Consequently, the quality of coupling between the gong and the bottom plate plays an important role as regards the acoustic power transmitted and the sound quality. 
   In the case of gongs of large length, such as the gongs fitted to pocket watches, or “cathedral” type gongs, which correspond to two turns around the bottom plate, the gong vibration amplitude can be significant. It sometimes happens that the gong enters into contact with the bottom plate, the middle part or the hammers, which denatures the sound produced. This contact can also occur via the effect of a shock and, in such case, the gong vibrates unexpectedly, thus being able to generate an unexpected and disagreeable sound. 
   The present invention overcomes these drawbacks by proposing a watch with a striking work fitted with a gong whose vibration amplitude is limited so as to prevent any contact between the gong and a neighbouring part, and thus coupling with the bottom plate is improved. 
   SUMMARY OF THE INVENTION 
   More specifically, the invention concerns a watch with a striking work including a support element and a gong forming a winding including two ends, said gong being secured via a first end to the support element. According to the invention, the second end of the gong is also secured to the support element. 
   In an advantageous embodiment, the bottom plate forms the support element. 
   Owing to the fact that both ends of the gong are secured to the bottom plate, the vibration amplitude is reduced and the transmission of vibratory energy is increased. Against all expectations, and contrary to a widespread prejudice according to which one of the ends of the gong has to be free, the acoustic quality and power are thus improved. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other features and advantages of the present invention will appear more clearly from the following detailed description of an example embodiment of a watch with a striking work according to the invention, this example being given purely by way of illustrative and non-limiting example, in conjunction with the annexed drawing, in which: 
       FIG. 1  is a schematic cross-section of a watch with a striking work according to the invention; 
       FIG. 2  is a top view of a bottom plate of the watch with a striking work shown in  FIG. 1 , and 
       FIGS. 3 and 4  are variants of the embodiment illustrated in  FIG. 2 . 
   

   DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS 
   The watch with a striking work shown schematically in  FIG. 1  includes, in a conventional manner, a case  10  formed of a middle part  12  and a back cover  14 , together defining a housing  16 . A movement  18  mounted on a bottom plate  20  is arranged inside housing  16 . A dial  19  is mounted on said movement, which drives a set of hands  21  in rotation. A gong  22 , forming a winding around movement  18 , is fixedly mounted on bottom plate  20 , via a first gong carrier  24  secured to bottom plate  20 . Gong  22  has a circular cross-section, but in a variant, it could have a rectangular cross-section. It is generally made of steel. 
   Gong carrier  24  is formed of a block screwed to bottom plate  20  and pierced with a hole  25  in which a first end of gong  22  is engaged and brazed. This securing method is well known to those skilled in the art. As an alternative, said first end of gong  22  could be welded to gong carrier  24 , or screwed between two counterparts. In another variant, gong  22  and the first gong carrier  24  form a single part secured to bottom plate  20 . In practice, those skilled in the art will chose the appropriate securing method in order to optimise the coupling between gong  22  and bottom plate  20 , so as to transmit a maximum vibration from gong  22  to bottom plate  20 . 
   Hammers  31 , shown in  FIG. 1  and in  FIG. 2 , are disposed to strike gong  22  in a substantially parallel plane to the general plane of the watch. These hammers  31  are controlled by a striking mechanism, such as a repeater mechanism, mounted on bottom plate  20 , but the repeater mechanism is not shown in  FIG. 1 . 
   A top view of bottom plate  20  of the watch with a striking work according to the invention is shown in  FIG. 2 , without movement  18 . The gong  22  forms a winding extending in a conventional manner over an angular sector of approximately 270 degrees. As mentioned previously, it is secured by a first end to bottom plate  20 , via first gong carrier  24 . 
   According to the invention, gong  22  is also secured to bottom plate  20  by its second end. Thus, a second gong carrier  26  is mounted integral to bottom plate  20 . The second end of gong  22  is secured to this second gong carrier  26  by a securing method of the same nature as that of the first end. In a variant, the second end could be secured differently. In another embodiment, gong  22 , first gong carrier  24  and second gong carrier  26  form a single part secured to bottom plate  20 . Whichever method is used to secure gong  22  to gong carriers  24 ,  26 , account will be taken of the fact that a phase opposition may occur between the waves respectively reaching the first and second gong carriers  24  and  26 . This phase opposition may lead to the extinction of one or several vibration frequencies, as a function of the length traveled from the point of impact of the hammers to gong carriers,  24 ,  26 , and the speed of propagation of the wave. The length of gong  22  must thus be chosen while taking this element into consideration. 
   According to a variant of the preceding arrangement, illustrated in  FIG. 3 , gong  22  is secured via both of its ends to a single gong carrier  28  extending over the angular sector comprised between the first and second end of gong  22 . 
   Finally,  FIG. 4  shows a bottom plate  20  of a watch with a striking work according to the invention, including two gongs wire respectively  22 ,  30 , of different lengths, for producing two different tonalities. The first two ends are conventionally secured to a common gong carrier  32  mounted on bottom plate  20 . The other two ends are secured to two gong carriers  34 ,  36  mounted integral with bottom plate  20 . As previously, wire gongs  22 ,  30  are secured to gong carriers  32 ,  34 ,  36  by brazing, or any other securing method. 
   Of course, the watch with a striking work according to the invention is not limited to the embodiment that has just been described and various simple alterations and variants could be envisaged by those skilled in the art without departing from the scope of the invention as defined by the annexed claims. 
   It will be noted, in particular, that gong  22  could be fixed to a different support element from bottom plate  20 , for example case  10 . In this type of embodiment, both ends of gong  22  are secured to case  10 , using one or two gong carriers  24 ,  26 ,  28 . In a variant, gong  22  is secured by one end to bottom plate  20  and by the other end to case  10 .