Patent Publication Number: US-8537641-B2

Title: Timepiece having a time indicator hand which is movable between two positions

Description:
BACKGROUND ART 
     The present invention relates to a timepiece including a time indicator hand which is movable between two positions to indicate two different pieces of time information. 
     Timepieces of this type are known in the prior art. 
     More specifically, EP 1 959 317 describes a timepiece which has a switch mechanism enabling the time indicator hand, for example the minute hand, to indicate two different pieces of information, such as the current time and the stop watch time, according to its movement, caused by the actuation of a push button, between a position for indicating the current time and a position indicating the stop watch time. 
     The switch mechanism which is described includes a transmission pinion rotated by a first moving part of the timepiece movement so as to represent a first piece of information to be displayed, and an element having a first split-second core mounted idly on the transmission pinion and rotated by the first moving part or by a second moving part of the movement so as to represent a second piece of information to be displayed. 
     The switch mechanism also includes a second split-second core fastened to the transmission pinion, a transmission wheel mounted idly on the transmission pinion and having a first and a second hammer biased against the first and second core respectively, a switch wheel mounted rotatably on the periphery of the transmission wheel and having a first and a second cam acting, respectively, on the first and the second hammer so as to separate, alternately, the contact between the first hammer and the first core and the contact between the second hammer and the second core respectively, in order to change the position of the transmission wheel according to the first or second piece of information to be displayed, respectively, an intermediate drive wheel being mounted idly on the transmission pinion and engaging with the switch wheel, the intermediate drive wheel being fastened to a drive wheel which can be rotated in a controlled way by means of a driving mechanism of the transmission mechanism. 
     The switch mechanism described in EP 1 959 317 is complex because of the use of numerous parts and their arrangement. In particular, it requires a transmission wheel with two hammers and a switch wheel with two cams. 
     Another switch mechanism for a timepiece enabling the minutes or the date to be indicated by the minute hand is described in CH 693 155. 
     This mechanism operates with a differential system and a planet gear fixed to a resetting cam, the differential system enabling an angular movement to be imparted to the minute hand to indicate a date. This mechanism is complex, and the planet carrier placed between the moving parts of the differential occupies a certain amount of vertical space. 
     Consequently there is a need to replace the existing switch mechanisms, and to simplify the timepiece movements, in timepieces in which a single time indicator hand can indicate two different pieces of information. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to overcome the aforementioned drawbacks, at least partially. 
     For this purpose, the present invention describes a timepiece having a timepiece movement and comprising a time indicator hand which can indicate a first piece of time information when in a first position, and a second piece of time information when in a second position; two concentric fixed scales for displaying the first and the second time indication respectively; and a first time indication moving part and a second time indication moving part, positioned concentrically and connected to the timepiece movement so as to be driven with two different periodicities. 
     The timepiece movement is distinctive in that it includes a first cam which is fixed to the first time indication moving part and which is shaped to shift the time indicator hand to its first position, a second cam which is coaxial with the first cam, is fixed to the time indicator hand and is rotatable with respect to the first cam, and which is shaped to shift the time indicator hand to the second position, a lever mounted pivotably on the second time indication moving part, actuating means for making the lever engage with the second cam in order to shift the time indication hand to the second position, and resilient return means engaged with the first cam to return the time indicator hand to the first position as soon as the lever ceases to engage with the second cam. 
     Advantageously, the resilient return means include a rotatable moving part to which the second cam is fastened and which can be rotated with respect to the first cam. 
     Also advantageously, the resilient return means include a pressure roller which moves on the first cam, and resilient means for returning the pressure roller into the recess of the first cam to position the time indicator hand in the first position, all these means being fastened to a face of the rotatable moving part opposite that to which the second cam is fastened. 
     Preferably, the rotatable moving part is fixed to a second tube to which the time indicator hand is fastened, and the first cam is fixed to a first tube which is fitted inside the second tube. 
     The lever has a first end which is substantially rounded and is intended to bear on the second cam, and a second end in the shape of a finger. 
     The means for actuating the lever include a transmission ring pivoting around the second time indication moving part and having, on its inner perimeter, teeth arranged so as to enable the lever to pivot with respect to the second time indication moving part by interaction between the second end of the lever and a tooth. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The appended drawing is a schematic illustration of a purely exemplary embodiment of the timepiece proposed by the present invention, which in this case is a wristwatch. 
         FIGS. 1 ,  2  and  3  are frontal views of the dial of the wristwatch, showing the display members, particularly the minute hand, and showing, respectively, a first position, a second position reached after the user has pressed a push button, and the first position which is resumed after the push button has been released; 
         FIGS. 4 and 5  are perspective views from above and below of the rotatable moving part used according to the invention to connect and disconnect a first cam and a second cam; 
         FIGS. 6 and 7  are plan views of the rotatable moving part and the two cams, in the first and second positions; 
         FIG. 8  is a plan view, from the dial side, of the timepiece movement according to the invention, in which the minute hand indicates the first position shown in  FIG. 1 ; 
         FIG. 9  is a view similar to that of  FIG. 8 , in which the minute hand indicates the second position shown in  FIG. 2 ; 
         FIG. 10  is a plan view, from the movement side, of the timepiece movement according to the invention. 
     
    
    
     DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS 
     The timepiece described below is, as shown in  FIGS. 1 to 3 , a wristwatch  1  indicating the time by means of an hour hand  2  and indicating the minutes by means of a minute hand  3 , the hands being placed in a first position which is read with respect to a first fixed time indicator scale  4 . 
     Because of the distinctive mechanism of the timepiece movement according to the invention described with the aid of  FIGS. 4 to 10 , one of the hands, which in the case of the illustrated embodiment is the minute hand  3 , is moved to a second position which is read with respect to a second fixed time indicator scale  5 , which in this case is a scale showing the date, after pressure on a push button  6  placed at the four o&#39;clock position on the wristwatch  1 . 
     The timepiece movement according to the invention includes a first cam  7 , shown in  FIGS. 4 to 7 , shaped to shift the minute hand  3  to a first position, and a second cam  8 , shown in  FIGS. 4 to 9 , which is fixed to the minute hand  3 , coaxial with the first cam  7 , rotatable with respect to the first cam  7 , and shaped to shift the minute hand  3  to the second position. 
     A first time indication moving part  9 , shown in  FIGS. 4 ,  5  and  10 , is fixed to the first cam  7  and is, in the illustrated embodiment, the cannon pinion linked to the motion work. 
     The cannon pinion  9  and the first cam  7  are fixed to a single tube  10  called the “first tube”. 
     A second time indication moving part  11 , shown in  FIGS. 8 to 10 , located coaxially and rotatably around the first time indication moving part  9 , is freely rotatable with respect to the second cam  8 . It is connected to the timepiece movement in such a way that it is driven with a periodicity different from that of the first time indication moving part  9 . In the embodiment described here, the second time indication moving part  11  is a date wheel. 
     A rotatable moving part  12  shown in  FIGS. 4 to 7  can be used to connect and disconnect the first cam  7  and the second cam  8 . It takes the form of a flywheel having a central part  13  to which the second cam  8  is fastened and a peripheral part  14 , such as a ring, connected to the central part  13  by three arms  15 . 
     The rotatable moving part  12  is fixed to a tube  16  called the “second tube” to which the minute hand  3  is fastened and inside which the first tube  10  is fitted. Resilient return means are fastened to the rotatable moving part  12 , on a face opposite the face to which the second cam  8  is fastened, and engage with the first cam  7 . They include a pressure roller  17 , connected to the ring  14  of the moving part  12  by a pivoting arm  18 . The pressure roller  17  moves against the first cam  7 . 
     A return spring  19  located on the ring  14  acts on the pivoting arm  18  and enables the pressure roller  17  to be returned to an equilibrium position corresponding to the positioning of the pressure roller  17  in the recess  7   a  of the first cam  7 , as shown in  FIG. 6 . Thus the rotatable moving part  12  is mounted so as to be rotatable with respect to the first cam  7 . 
     As shown in  FIGS. 6 to 10 , a drive lever  20  of the second cam  8  is mounted pivotably on the date wheel  11  so as to engage with the second cam  8  in order to shift the minute hand  3  to the second position. Since it is positioned on the date wheel  11 , it moves together with the latter with respect to the second cam  8 . 
     It has a first substantially rounded end  21  intended to bear on the second cam  8  in order to move it to the second position, and a second end  22  in the shape of a finger. 
     As shown in  FIGS. 8 and 9 , the lever  20  is rotated by the interaction of its second finger-shaped end  22  with actuating means. 
     The means for actuating the lever  20  include a toothed transmission wheel  23  and a transmission ring  24  positioned coaxially and rotatably around the date wheel  11 , the toothed transmission wheel  23  carrying the transmission ring  24 . 
     The inner perimeter of the transmission ring  24  has teeth  25  which interact with the second end  22  of the lever  20 , thus enabling the lever  20  to pivot with respect to the date wheel  11 . 
     A return spring  26  acts on a pin  27  located on an intermediate part of the lever  20  in order to keep the lever fixed with respect to the date wheel  11  when the lever  20  is not moved by a tooth  25 . 
     The actuating means also include an L-shaped rocker  29  connected mechanically to a drive wheel  30  by the pressure of the end of the rocker  29  on a pin  31  of the drive wheel. The drive wheel  30  engages with the toothed transmission wheel  23 . 
     A projection  32 , coaxial with and fixed to a toothed wheel  33  engaging with the toothed transmission wheel  23 , pivots and bears with a curved surface on a jumper spring  34  to hold it between two teeth of the date wheel  11  in order to prevent any unintended movement of the latter in the course of the request for the date. 
     A return spring  35  enables the transmission ring  24 , the toothed transmission wheel  23  and the toothed drive wheel  30  to return, after the release of the push button  6 , to the respective positions which they assumed before the push button  6  was pressed. 
     As shown in  FIGS. 8 ,  9  and  10 , the date wheel  11  has  31  uniformly distributed teeth, giving it the shape of a star. It is freely rotatable with respect to the second cam  8 , while it is connected mechanically to the pinion  9  and thus to the first cam  7 . 
     As shown in  FIG. 10 , the date wheel  11  is connected to the pinion  9  by a set of moving parts comprising a return pinion  36  engaging with the pinion  9  and with a first intermediate toothed wheel  37  having at its centre a pinion  38  engaging with a second toothed wheel  39  completing one revolution per day. 
     The second toothed wheel  39  engages with the hour wheel  40  and has in its centre a drive finger  41  of the date wheel  11 . The drive finger  41  causes the date wheel  11  to rotate with respect to the dial, together with the lever  20  fastened to the date wheel  11 , through one interval per day, thus enabling a new date to be indicated every day. 
     The operation of the timepiece mechanism described above is as follows. 
     When the user presses the push button  6  to discover the date, the movement of the push button  6  drives the rocker  29  which drives, by means of the pin  31 , the drive wheel  30 , the transmission wheel  23  and the transmission ring  24  whose teeth  25  drive the lever  20 . The drive lever  20  then pivots in the direction of the hands of the watch  1 , as a result of the movement of its second end  22  which is driven by the tooth  25 , as shown in  FIGS. 7 and 9 , and its first end  21  comes into contact with the second cam  8  which is fixed to the minute hand  3 . 
     The second cam  8  is then driven by the pivoting of the lever  20 . The rotatable moving part  12  fixed to the second cam  8  and to the second tube  16  pivots around the first tube  10 . The movement of the rotatable moving part  12  stops as soon as the lever  20  is in the recess  8   a  of the second cam  8 , and in this case the minute hand  3  is located in the second position, corresponding to the second time indication. 
     When the user releases the push button  6 , the rotatable moving part  12  and the second cam  8  are returned under the action of the resilient means and the pressure roller  17 , thus causing the rotation of the second tube  16  and of the second cam  8  around the first tube  10 , until the pressure roller  17  is located in the recess  7   a  of the first cam  7  corresponding to the first position of the minute hand  3 . 
     The lever  20  is then driven in the opposite direction to the hands of the watch  1 , by means of its first rounded end  21  which is in contact with the second cam  8 . The pin  27  of the lever  20  locks into the fork of the return spring  26 . 
     The transmission wheel  23  and the transmission ring  24  are driven in the opposite direction to the hands of the watch  1  by the return spring  35 , causing the movement of the drive wheel  30  and consequently the movement of the rocker  29  by means of the pin  31 . 
     In this case, the second cam  8  and the rotatable moving part  12  are driven together with the first cam  7 , and consequently with the pinion  9 , by means of the pressure roller  17 . The minute hand  3 , fixed to the second cam  8  by the second tube  16 , follows the movement of the pinion  9  and indicates the first position. In other words, the first tube  10  and the second tube  16  pivot together. 
     Thus the resilient return means, particularly the rotatable moving part  12  and the pressure roller  17 , are connected to the first cam  7  when the push button  6  is released and are disconnected from the first cam  7  when the push button  6  is pressed and the lever  20  is in contact with the second cam  8 . 
     Other arrangements of the rotatable moving part  12 , the two cams  7  and  8 , the first tube  10  and the second tube  16  are possible, the essential feature being that the second cam  8  can pivot with the first cam  7  without the action of the lever  20  and can pivot independently of the first cam  7  under the action of the lever  20 , this lever being mounted on the date wheel  11  and being moved once every day at a given frequency with respect to the dial of the timepiece. 
     The present invention can be applied to any time indication, for example a power reserve indicator, as an alternative to the date indication, and can be applied to any time indicator hand, for example the hour hand  2 , as an alternative to the minute hand  3 . 
     In a variant, it would be possible to connect the date wheel  11  to a perpetual date mechanism.