Abstract:
A trigger mechanism for remotely operating the chronograph functions of a watch. A lever mounted to the watchcase is swingable about a pivotal connection for rotating a cylindrical cam. A rotary cam follower is displaced by the cam. A striker member extending from the cam follower actuates a pushbutton for controlling the chronograph functions.

Description:
REFERENCE TO RELATED APPLICATION 
     This application is related to a design patent application (Ser. No. 29/390,683) filed Apr. 28, 2011, now U.S. Design Pat. No. D646,588 and is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to horology and especially to watches having stop/start and/or reset functions. 
     In particular, this invention concerns a trigger mechanism for mechanically actuating the chronograph functions of a watch. 
     2. Description of Related Art 
     Chronograph watches typically include one or more pushbuttons, pushers, depressors, pressure switches, or equivalent devices, mounted for movement relative to a watchcase within which is housed a watch movement including one or more elements that are adapted to be actuated by the operation of the one or more pushbuttons, for example, as shown in U.S. Pat. No. 4,364,674 and U.S. published application no. US2006/0164922. This arrangement is generally found in both mechanical and electronic watches for operating the various functions, such as the stop/start systems in stopwatches and the time display systems in electronic watches. 
     The pushbuttons are typically actuated manually by finger manipulation. This procedure does not readily achieve precision timing as may be needed for sporting events and similar activities. In manually operated chronographs the flesh surrounding the finger-tip cushions the actuation of the pushbutton and may cause variations in timing precision. Also, gloves covering the finger tip, can create timing imprecision. 
     An attempt to enhance stopwatch precision is shown in U.S. Pat. No. 5,224,077, however, the device of that patent is not an integral part of the watchcase and is cumbersome to use. 
     Another timepiece, shown in U.S. Pat. No. 3,759,033, is intended to actuate a pushbutton by use of a pivotal key. That device however, does not apply mechanical linkage for transforming the movement of the key into a reciprocal movement for actuating the pushbutton for improved precision as in the present invention. 
     A further device for operating a chronograph is disclosed in U.S. Pat. No. 7,570,545. The rocker mechanism of that device lacks the precision control achievable with the present invention. 
     SUMMARY OF THE INVENTION 
     Briefly, this invention concerns a trigger mechanism for operating a chronograph watch having a watchcase with a switch member for controlling the chronograph functions comprising, a striker member for remotely actuating the switch, a lever having a pivotal connection to the watchcase for swingable movement about the pivotal connection, mechanical linkage for transforming said pivotal movement of the lever to reciprocal movement of the striker member between a rest position and a stroke position with said switch member being actuated when the striker member is in the stroke position. 
     Having thus summarized the invention, it will be seen that it is a preferred object thereof to provide a trigger mechanism for a chronograph watch of the general character described herein which is not subject to the previously mentioned limitations. 
     Another preferred object of this invention is to provide a trigger mechanism for a chronograph watch for remote actuation of the pushbutton. 
     Yet still another preferred object of this invention is to provide a trigger mechanism for a chronograph watch wherein a mechanical force is generated and selectively applied on the pushbutton for improved precision of operation. 
     A further preferred object of this invention is to provide a trigger mechanism for a chronograph watch wherein the pushbutton actuation is mechanically linked to a pivotal lever. 
     With these ends in view, the invention finds embodiment in certain combinations of elements and arrangements of parts by which the aforementioned preferred objects and certain other objects are hereinafter attained, all as more fully described with reference to the accompanying drawings and the scope of which is more particularly pointed out hereinafter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the accompanying drawings, in which is shown an exemplary embodiment of the invention: 
         FIG. 1  is a partial perspective view of a watch showing a trigger mechanism in accordance with this invention; 
         FIG. 2  is a sectional view taken substantially along line  2 - 2  of  FIG. 1 , with a portion broken away, for illustrating a spring-urged pushbutton mounted within a watchcase; 
         FIG. 3  is an exploded perspective view, to an enlarged scale, detailing a lever having at its distal end a cylindrical cam member and a complementary rotary cam follower; 
         FIG. 4  is a plan view of a portion of the watchcase, with a section broken-away, illustrating, by arrows, rotational movement of the lever and the cam member with respect to the cam follower; and 
         FIG. 5  is a plan view of the watchcase of  FIG. 4  showing, by arrows, the rotational displacement of the cam follower having a striker member for engaging the pushbutton to actuate a chronograph function of the watch. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With specific reference now to the figures in detail, it is stressed that the particulars shown are by way of example and for the purposes of illustrative discussion of the preferred embodiment of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt has been made to show aspects of the invention in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings should make it apparent to those skilled in the art how the preferred form of the invention may be embodied in practice. 
     Referring now in detail to  FIG. 1  of the drawings, there is shown a trigger mechanism  10  for a chronograph watch  12  of this invention. The trigger mechanism  10  provides for remote operation of the chronograph functions of the watch  12 . It should be understood that the watch  12  can be a digital and/or analog chronograph or an analog-digital chronograph. Additionally the trigger mechanism  10  can be utilized with stopwatches that do not have timekeeping functions. 
     As shown in  FIG. 1 , the watch  12  has a watchcase  14  for housing a watch movement (not shown) and a crown  16  connected to a watch stem (not shown) extending internally within the watchcase  14 . The watchcase  14 , further has a front face  18 , a rear face  20  and a peripheral sidewall  22 . 
     The trigger mechanism  10 , as shown in this embodiment, is positioned on opposite sides of the crown  16 . Since the component elements and operation of each trigger mechanism  10  shown is substantially identical, the invention will be described with regard to the trigger mechanism  10  located at the four o&#39;clock position on the watch  12 . 
     The sidewall  22  includes an upper aperture disc  24  extending from the front face  18  and a lower aperture disc  26  extending from the rear face  20 . A lever  28 , as shown in  FIG. 3 , has an open cylindrical cam member  30  at its distal end. The cam member  30  is defined by a cylindrical wall  32  that extends partially around the periphery and by a respective top end member  31  and bottom end member  33 . The end members  31 ,  33  are adapted to support the cam member  30  between the respective discs  24  and  26 . 
     The wall  32  further defines a cam surface  34 . A complimentary rotary cam follower  36  has an axial bore  38 , and is accommodatable within the cam member  30 . A pivot pin  40  secures the cam follower  36  and cam member  30  to the discs  24 ,  26  for concentric rotation relative to each other about the pin  40 . Further with regard to the cam follower  36 , a follower tooth  42  is adapted for abutting contact with the cam surface  34 . The cam follower  36  is also provided with a striker member  44  that is registrable with a push-switch, such as pushbutton  46 , that controls the chronograph functions of the watch  12 . It should be understood that equivalent switch devices are considered to be within the scope of this invention. 
     Referring now to  FIG. 2 , there is shown, in partial sectional view, the pushbutton  46  housed within a recess  48  in the sidewall  22  of the watchcase  14 . The recess has a window  49  for accommodating the striker member  44 . The pushbutton  46  is adapted to be depressed, in opposition to a spring-force, by the striker member  44  to thus actuate the chronograph functions. The Operation of a chronograph is otherwise known in the art. It should be further noted that the pushbutton  46  resiliently urges the striker member  44  to a rest position as shown in  FIG. 2 . The striker member  44  when under the influence of the resilient urging force, is secured within the window  49  by a notch  47  formed in the end of the striker member  44 . The notch  47  engages a lip  50  to retain the striker member  44  within the window  49 . 
     The operation of the trigger mechanism  10  will now be described with particular reference to  FIGS. 4 and 5 . When it is desired to actuate the chronograph function of the watch  12 , a proximal end of the lever  28  is released from a docked position, as shown in  FIG. 2 , adjacent sidewall  22  of the watchcase  14 . Note that the sidewall  22  defines a crescent-shaped depression  51  for permitting fingertip access to the lever  28 . Additionally, a spring-loaded ball  52  within a ledge  54  is engageable with a detent  56  in the lever  28  to secure the lever  28  in the docked position. The lever  28  is swingably displaced, as indicated by the arrows in  FIG. 4 , and the cam surface  34  will approach the cam follower  36 . As the lever  28  continues moving, the cam surface  34  will traverse the angular distance  58 , to contact the cam follower tooth  42  as shown in  FIG. 5 . Further movement of the lever  28  will rotate the cam follower  36  and the striker member  44  to a stroke position to contact and exert a force, upon the pushbutton  46 , as indicated by the arrows, and to thus actuate the chronograph function. When the lever  28  is then restored to the docked position, the pushbutton  46  will urge the striker member  44  to a reciprocal rest position wherein the lip  50  will secure the striker member  44  in the window  49  as shown in  FIG. 4 . 
     It should thus be apparent that the trigger mechanism  10  achieves the various preferred objects of this invention and is well adapted to meet conditions of practical use. Since other various possible embodiments might be made to the present invention or modification might be made to the exemplary embodiment set forth above, it is to be understood that all materials shown and described with reference to the accompanying drawings are to be interpreted as illustrative and not in a limiting sense.