Patent Publication Number: US-2023161297-A1

Title: Timepiece movement comprising a countdown chronograph mechanism and a striking mechanism

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is the U.S. national phase of International Application No. PCT/EP2021/060999 filed Apr. 27, 2021, which designated the U.S. and claims priority to EP Patent Application No. 20172014.1 filed Apr. 29, 2020, the entire contents of each of which are hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a mechanical timepiece movement comprising a chronograph mechanism arranged to be capable of carrying out at least one countdown of a predetermined time interval, comprising display means arranged to display at least the time remaining until the end of the countdown of said time interval, at least one member for controlling the start of the countdown, and a striking-mechanism. 
     Description of the Related Art 
     Such a movement is described, for example, in patent CH 704 705. A striking countdown mechanism is provided, making it possible to count down a predetermined period of time which can be adjusted up to 11:55 in jumps of five minutes. A control which can be actuated by a push-piece makes it possible to start the countdown. The end of the countdown is indicated by a mechanical striking-mechanism. The time remaining is given by two indicating disks for the hours and minutes. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to provide an improved mechanical timepiece movement with respect to the known striking countdown mechanism. 
     To this end, the present invention relates to a mechanical timepiece movement comprising a chronograph mechanism arranged to be capable of carrying out at least one countdown of a predetermined time interval, comprising display means arranged to display at least the time remaining until the end of the countdown of said predetermined time interval, at least one member for controlling the start of the countdown, and a striking-mechanism. 
     According to the invention, said striking-mechanism is arranged to start striking at a specified time before the end of the countdown and to stop striking at the end of said countdown of said predetermined time interval. 
     Thus, the invention makes it possible to trigger a striking-mechanism before the end of the countdown of said predetermined time interval in order to warn a user that the current countdown of the predetermined time interval is about to come to an end. Thus, the present invention makes it possible to have a countdown of a predetermined time interval having a pre-alarm using a mechanical striking-mechanism, and to be capable of synchronizing the end of the striking with the end of the countdown of said predetermined time interval. 
     Advantageously, the chronograph mechanism comprises at least one chronograph drive wheel and pinion arranged to be capable of performing a countdown, and in particular the countdown of the predetermined time interval, and the striking-mechanism comprises at least one first cam kinematically linked to said chronograph drive wheel and pinion and on which said specified time before the end of the countdown of said predetermined time interval is programmed, said first cam being arranged to make one revolution over a time greater than the specified time before the end of the countdown of said predetermined time interval, a striking geartrain, a first striking lever comprising a first striking feeler lever arranged to be capable of cooperating with said first cam and said striking geartrain in order to trigger the striking at the start of the specified time before the end of the countdown of said predetermined time interval and an end of striking mechanism arranged to be capable of cooperating with said first striking lever in order to control the stopping of the striking at the end of said specified time at the same time as the end of the countdown of said predetermined time interval. 
     The display means of the chronograph mechanism can preferably comprise a first display member associated with the first cam for displaying a countdown obtained via the chronograph drive wheel and pinion. 
     According to a first embodiment of the invention, the first display member is arranged to display a minute unit countdown. 
     According to a second particularly preferred embodiment of the invention, the first display member is arranged to display a second countdown. 
     According to the second embodiment, the display means of the chronograph mechanism can comprise a second minute unit display member arranged to display the minute unit countdown of said predetermined time interval and the striking-mechanism comprises a second minute unit cam associated with said second minute unit display member, and a third minute unit feeler lever arranged to be capable of cooperating with said second minute unit cam, said second minute unit cam being programmed to indicate the end of the minute unit countdown to the third minute unit feeler lever, said third minute unit feeler lever being arranged to cooperate with the first striking feeler lever such that said first striking feeler lever comes to cooperate with the first cam at the end of the minute unit countdown. 
     According to the second embodiment, the display means of the chronograph mechanism can comprise a third tens of minutes display member arranged to display the tens of minutes countdown of said predetermined time interval and the striking-mechanism comprises a third tens of minutes cam associated with said third tens of minutes display member, and a fourth tens of minutes feeler lever arranged to be capable of cooperating with said third tens of minutes cam, said third tens of minutes cam being programmed to indicate the end of the tens of minutes countdown to the fourth tens of minutes feeler lever, said fourth tens of minutes feeler lever being arranged to cooperate with the third minute unit feeler lever such that said third minute unit feeler lever comes to cooperate with said second minute unit cam at the end of the tens of minutes countdown. 
     According to the first embodiment, the display means of the chronograph mechanism can comprise a third tens of minutes display member arranged to display the tens of minutes countdown of said predetermined time interval and the striking-mechanism comprises a third tens of minutes cam associated with said third tens of minutes display member, and a fourth tens of minutes feeler lever arranged to be capable of cooperating with said third tens of minutes cam, said third tens of minutes cam being programmed to indicate the end of the tens of minutes countdown to the fourth tens of minutes feeler lever, said fourth tens of minutes feeler lever being arranged to cooperate with the first striking feeler lever such that said first striking feeler lever comes to cooperate with said first cam at the end of the tens of minutes countdown. 
     Regardless of the embodiment, the display means of the chronograph mechanism can comprise a fourth hour display member arranged to display the hour countdown of said predetermined time interval and the striking-mechanism comprises a fourth hour cam associated with said fourth hour display member, and a fifth hour feeler lever arranged to be capable of cooperating with said fourth hour cam, said fourth hour cam being programmed to indicate the end of the hour countdown to the fifth hour feeler lever, said fifth hour feeler lever being arranged to cooperate with the fourth tens of minutes feeler lever such that said fourth tens of minutes feeler lever comes to cooperate with said third tens of minutes cam at the end of the hour countdown. 
     Advantageously, the third minute unit feeler lever, the fourth tens of minutes feeler lever and the fifth hour feeler lever can form a single lever, optionally also with the first striking feeler lever. 
     The chronograph mechanism is preferably configured to be capable of being kinematically connected to a base movement by a lateral or vertical clutch device. 
     Advantageously, according to an embodiment, the end of striking mechanism comprises an end of striking lever comprising a second end of striking feeler lever arranged to be capable of cooperating with the first cam in order to control a disconnection of the clutch device and the stopping of the striking at the end of the countdown of said predetermined time interval. 
     According to this embodiment, the chronograph mechanism, and in particular the chronograph seconds-hand, stops automatically at the end of the countdown of the predetermined time interval. 
     According to another embodiment, the end of striking mechanism comprises an end of striking lever arranged to cooperate with the first striking lever and a stopping of striking cam kinematically linked to said chronograph drive wheel and pinion and arranged to control the end of striking lever in order to stop the striking at the end of the countdown of said predetermined time interval without disconnecting the clutch device. 
     According to this embodiment, the chronograph mechanism, and more particularly its chronograph drive wheel and pinion, remains activated after the end of the countdown of the predetermined time interval. Thus, the first display member, and more particularly the chronograph seconds-hand, continues turning without triggering striking. A manual stoppage by a user will be necessary to stop the chronograph mechanism. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other features and advantages of the present invention will become apparent on reading the following detailed description of different embodiments of the invention, provided by way of nonlimiting example, and with reference to the appended drawings, wherein: 
         FIG.  1    shows a schematic view of a first embodiment of a movement according to the invention, the chronograph mechanism being in the STOP position; 
         FIGS.  2  to  9    show schematic views of the movement of  FIG.  1    in different positions between a countdown start and a countdown end, the control device being ready to operate; 
         FIG.  10    shows a schematic view of a second embodiment of a movement according to the invention; 
         FIG.  11    shows a schematic view of the display members for hours, tens of minutes, and minute units; 
         FIG.  12    shows a schematic view of another embodiment of a movement according to the invention, the chronograph mechanism being in the STOP position before the start of a countdown of a predetermined time interval; 
         FIGS.  13  to  20    show schematic views of the movement of  FIG.  12    in different positions between a countdown at a minute from the end and the end of the countdown of the predetermined time interval, and 
         FIG.  21    shows a view of the movement of the figure in the STOP position during striking. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to  FIG.  1   , the present invention relates to a mechanical timepiece movement comprising a chronograph mechanism arranged to be capable of carrying out at least one countdown of a predetermined time interval. In the present description, the term “chronograph mechanism” should be considered in the broad sense of the term, that is to say as comprising all the necessary elements or components arranged to produce at least one countdown of time and fraction of time in order to perform at least one countdown. 
     The chronograph mechanism is shown here schematically by a chronograph drive wheel and pinion  1 , a drive wheel  2  making one revolution per minute here, corresponding to a chronograph seconds-wheel, said drive wheel  2  being arranged to cooperate with the other components of the chronograph to be capable of performing a countdown and, in particular, a countdown of a predetermined time interval. The chronograph mechanism, and more particularly the chronograph drive wheel and pinion  1 , is arranged to be capable of being kinematically connected to the seconds-wheel  4  of a base timepiece movement indicating the current time by a vertical clutch device  6 . Said vertical clutch device  6  comprises a clutch control clamp  8  and a clutch clamp  10  arranged to move apart when the chronograph is activated in order to launch a countdown in such a way as to engage the seconds-wheel  4  and the chronograph drive wheel and pinion  1 , making it possible to transmit energy from the base movement to the chronograph mechanism for its operation. 
     It is obvious that the clutch device could be lateral, with the construction of the movement being adapted by the person skilled in the art to this type of clutch. 
     The chronograph mechanism also comprises a member  11  for controlling the start of the countdown arranged to control at least the triggering of the chronograph mechanism, and in particular the opening of the clamps  8  and  10 , via a control device  12  comprising a column wheel  14 . This control member  11  is, for example, a push-piece. It can be arranged to also control the stopping of the chronograph mechanism, and in particular the closing of the clamps  8  and  10 , during the countdown if necessary. 
     In the first embodiment of the invention according to  FIGS.  1  to  9   , the chronograph mechanism is arranged to be stopped automatically at the same time as the striking-mechanism. 
     To this end, the control device  12  advantageously comprises a main control  13  which can be actuated by the control member  11 , and a secondary control  15  pivotally mounted on the main control  13  and to which it is linked by an elastic member (not shown). The main control  13  and secondary control  15  are respectively terminated by a hook  13   a,    15   a.  The column wheel  14  comprises a first drive wheel  14   a  rigidly connected to the columns  14   b  and arranged to be actuated by the hook  15   a  of the secondary control  15 , and a second drive wheel  14   c  arranged to be actuated by the hook  13   a  of the main control  13 . The control device  12  also comprises a locking mechanism in rotation of the secondary control  15  on the main control  13 , which is arranged to be capable of being controlled manually by the control member  11  as well as internally, automatically, by an internal control member, here the hook  56  of the end of striking lever  50  as will be described below. 
     The locking mechanism and the secondary control  15  are arranged to occupy a locked state in which the elastic member connecting the main control  13  and secondary control  15  is wound and the secondary control  15  is constrained to rotate with the main control  13  making it possible, during an actuation of the main control  13  via the actuating member  11 , to simultaneously actuate the column wheel  14  by the main control  13  and secondary control  15 , and to be capable of passing, in the event that the locking mechanism is actuated by the hook  56 , into an unlocked state in which said secondary control  15  is detached from the main control  13  and actuates, alone, the column wheel  14 , the elastic member unwinding, and to pass through a locking position, through an actuation of the main control  13 , in which only the main control  13  actuates the column wheel  14 , said main control  13  being arranged to rewind the elastic member and to cooperate with the locking mechanism of the secondary control  15  in order to return to the locked state. 
     The second drive wheel  14   c  is connected to the first drive wheel  14   a  by an elastic coupling element (not shown) arranged to link, in a manner constraining rotation, the second drive wheel  14   c  to the first drive wheel  14   a  when only the second drive wheel  14   c  is actuated by the hook  13   a  of the main control  13 , if the secondary control  15  has passed to the unlocked state and then only the main control  13  is actuated during the next manual actuation via the control member  11 , and in order to detach the second drive wheel  14   c  from the first drive wheel  14   a  when only the first drive wheel  14   a  is actuated, thanks to the energy supplied by the elastic member which unwinds, by the secondary control  15 , after having been detached from the main control  13 . 
     More particularly, the locking mechanism comprises a control lever  19  arranged to be controlled by the hook  56  in order to pass to the unlocked state and to be capable of cooperating with a pin  21  provided on the main control  13  in order to pass into the locking position then to the locked state. The locking mechanism also comprises a locking hook  22  carried by the main control  15  and arranged to be controlled by said control lever  19  via a pin  23  in order to pass to the unlocked state and to be capable of cooperating with a hook  15   b  provided on the secondary control  15  in order to pass into the locking position then to the locked state. 
     This control device of the chronograph mechanism makes it possible for it to be capable of being actuated by a user, but also by an internal control linked to the striking-mechanism, in such a way as to have an automatic control, in addition to a manual control of said chronograph mechanism, in order to stop the chronograph mechanism at the same time as the striking-mechanism. 
     Such a control device is described in greater detail in the applicant&#39;s European application No. EP 20171993. 
     Any other suitable control device known to the person skilled in the art can also be used. 
     In particular, it is possible to use a standard control device with a column wheel, controlled by a push-piece, in order to carry out the start/stop control of the chronograph mechanism manually and in a conventional manner, as will be described below in relation to another embodiment of the invention. 
     Notwithstanding the embodiments of the invention, the chronograph mechanism also comprises display means arranged to display at least the time remaining until the end of the countdown of the predetermined time interval. In the variant shown in  FIG.  1   , these display means comprise a first display member for displaying a second countdown and, in particular, the second countdown of the predetermined time interval, a second display member for displaying the minute unit countdown of the predetermined time interval, a third display member for displaying the tens of minutes countdown of the predetermined time interval and a fourth display member for displaying the hour countdown of the predetermined time interval. 
     These display means can be disks, hands, rollers or any other suitable display member for displaying the countdown of the hours, tens of minutes and minute units, as well as the seconds. 
     The first display member for the seconds is preferably a hand (not shown) corresponding to the seconds-hand. 
       FIG.  11    shows a preferred embodiment of the display members for displaying the countdown of the hours, tens of minutes and minute units of the predetermined time interval, used in the present invention in the form of disks, the first display member for the seconds being a hand (not shown) corresponding to the seconds-hand. More specifically, the second display member for counting down the minute units of the predetermined time interval is a disk  16  carrying the digits 0 to 9 regularly distributed on its periphery, said disk  16  being arranged to make one revolution in ten minutes. The third display member for counting down the tens of minutes of the predetermined time interval is a disk  18  disposed tangentially to the minute unit disk  16 . The tens of minutes disk  18  carries two consecutive series of digits 0 to 5 regularly distributed on its periphery, said disk  18  being arranged to make one revolution in two hours. The fourth display member for counting down the hours of the predetermined time interval is a disk  20 , disposed concentrically inside the tens of minutes disk  18 . The hour disk  20  carries a series of digits 0 to 6 regularly distributed on its periphery, said disk  20  being arranged to make one revolution in seven hours. The centers of the three disks  16 ,  18  and  20  are aligned, making it possible to display the countdown of the hours, tens of minutes and minute units of the predetermined time interval in juxtaposed apertures to make it easy to read the countdown. 
     It is obvious that the display members for the hours, tens of minutes and minute units of the predetermined time interval can be arranged differently, the striking-mechanism being adapted accordingly, as will be described below. 
     The different display members can be arranged to be driven, one after the other, from the second to the hour, starting for example from the drive wheel  2 . In another variant, the first display member for displaying the second countdown can be kinematically linked to the drive wheel  2  and an auxiliary energy source can be provided in order to supply energy to the display member for counting down the minute units, which drives the display member for counting down the tens of minutes, itself driving the display member for counting down the hours, for example by means of actuating fingers and stars which cooperate in order to cause the display member to jump corresponding to each tens of minutes or hour change. 
     An adjustment mechanism (not shown) is provided, which makes it possible to position, before the triggering of the countdown of the predetermined time interval, the different display members for counting down the hours  20 , tens of minutes  18  and minute units  16  in such a way as to display the predetermined time interval to be counted down, said time interval to be counted down being adjustable for example up to 6:59. 
     Thus, when the countdown of the predetermined time interval is triggered, the different display members are arranged to display the time remaining which decreases as the countdown progresses, from the value of the predetermined time interval up to 0:00:00, in a very precise manner, down to the second. 
     Such a construction of a countdown chronograph mechanism cooperating with a base movement via a clutch device is known to the person skilled in the art and does not need to be described in greater detail. 
     The mechanical movement according to the invention also comprises a striking-mechanism made up of mechanical components and comprising, in particular, a striking geartrain shown here by an element  30  of the striking geartrain carrying a stopping star  32  of the striking geartrain. These components of a striking-mechanism are known to the person skilled in the art and do not need to be described in detail. 
     In accordance with the invention, the striking-mechanism is arranged so that the striking-mechanism starts striking at a specified time before the end of the countdown of the predetermined time interval, and stops striking at the end of the countdown, that is to say at the same time as the countdown of said predetermined time interval reaches 0:00:00. 
     To this end, the striking-mechanism comprises at least one first cam  34  kinematically linked to the chronograph drive wheel and pinion  1  and on which said specified time before the end of the countdown of said predetermined time interval is programmed, said first cam  34  being arranged to make one revolution over a time greater than the specified time before the end of the countdown of said predetermined time interval. The first cam  34  is associated with the first display member for displaying at least the countdown of said predetermined time interval obtained via the chronograph drive wheel and pinion  1 . In the present example, the first cam  34  is the second cam, associated with the first display member (i.e., the seconds-hand) in order to display a second countdown. Here, the first cam  34  therefore makes one revolution per minute. 
     More particularly, the first cam  34  has a substantially circular profile and comprises a notch  36 , the circular length of which corresponds to the specified time of the striking before the end of the countdown of the predetermined time interval, the start  36   a  of the notch  36  corresponding to the triggering of the striking, and the end  36   b  of the notch  36  corresponding to the stopping of the striking, at the same time as the stopping of the countdown of said predetermined time interval, as will be described in detail below. For example, the length of the notch  36 , between the start  36   a  and the end  36   b  of said notch  36 , can correspond to a time of 20 seconds before the end of the countdown of said predetermined time interval. 
     The striking-mechanism also comprises a first striking lever comprising a first striking feeler lever  38  arranged to be capable of cooperating with the first cam  34  and the striking geartrain in order to trigger the striking at the start of the specified time before the end of the countdown of said predetermined time interval. 
     The striking-mechanism also comprises an end of striking mechanism arranged to be capable of cooperating with said first striking lever in order to control the stopping of the striking at the end of said specified time at the same time as the end of the countdown of said predetermined time interval. 
     In the first embodiment of the invention according to  FIGS.  1  to  9   , in which the chronograph mechanism is arranged to be stopped automatically at the same time as the striking-mechanism, the first second cam  34  is carried by the drive wheel  2  which meshes with the chronograph drive wheel and pinion  1 . 
     The first striking feeler lever  38  constitutes the first arm of a striking lever  41  pivotally mounted at A. The first striking feeler lever  38  has a beak  38   a  arranged to be capable of coming into contact with the first second cam  34  then of engaging in its notch  36  at the time of the striking, as will be described in greater detail below. 
     Said striking lever  41  comprises a second arm  42  arranged to control a stopping of striking lever  44  pivotally mounted at D, a pin  43  rigidly connected to the second arm  42  providing the link to said lever  44  via an oblong opening  45 , said stopping of striking lever  44  itself being arranged to be capable of cooperating with the stopping star  32  of the striking geartrain. The striking lever  41  comprises a third arm  46  including a heel  46   a  arranged to be capable of cooperating with a pin  48  carried by the clutch clamp  10 . 
     The operation of the different elements of the striking lever  41  will be described below. 
     The end of striking mechanism comprises an end of striking lever  50  pivotally mounted at B and provided with a second end of striking feeler lever  40  arranged to be capable of cooperating with the first cam  34  in order to control the stopping of the striking at the end of said specified time at the same time as the end of the countdown of said predetermined time interval. Thus, in this embodiment of the invention, the first cam  34  provided with its notch  36  is also part of the end of striking mechanism and constitutes both a start of striking cam and a stopping of striking cam. 
     The second end of striking feeler lever  40  constitutes the first arm of the end of striking lever  50 . 
     More specifically, the second end of striking feeler lever  40  has a beak  40   a  arranged to be capable of coming into contact with the first second cam  34  when the first striking feeler lever  38  falls into the notch  36  of said first cam  34  in order to trigger the striking and in order to engage in said notch  36  at the end of the countdown and of the striking, as will be described in greater detail below. 
     The end of striking lever  50  comprises a second arm  54  carrying, at its free end, a hook  56  mounted pivotally at C and held in position by a pin  58  carried by the end of said second arm  54 . The pivoting hook  56  is arranged to cooperate with the control device  12 , as will be described below. In particular, the second end of striking feeler lever  40  is arranged to control, via said hook  56 , a disconnection of the clutch device  6  and the stopping of the striking when said second end of striking feeler lever  40  falls into the notch  36  at the end of the countdown. 
     The end of striking lever  50  further comprises a third arm  60 , in the extension of the second end of striking feeler lever  40 . Said third arm  60  comprises a first beak  60   a  arranged to be capable of cooperating with the foot  46   b  of the third arm  46  of the striking lever  41  and a second beak  60   b  arranged to be capable of cooperating with the pin  48  of the clutch clamp  10 . 
     The operation of the different elements of the end of striking lever  50  will be described below. 
     In the variant shown here, the striking-mechanism comprises a second minute unit cam  62  associated with the second minute unit display member  16  in order to make one revolution in ten minutes, for example, and a third minute unit feeler lever  64  arranged to be capable of cooperating with said minute unit cam  62 , said minute unit cam  62  being programmed to indicate the end of the minute unit countdown to the third minute unit feeler lever  64 . To this end, the minute unit cam  62  has a substantially circular profile and includes a notch  66 , said third minute unit feeler lever  64  being arranged to be positioned in said notch  66  when the display members for the hours, tens of minutes and minute units all display  0 , that is to say as of the moment when there is less than a minute to be counted down. 
     Furthermore, the third minute unit feeler lever  64  is arranged to cooperate with the first striking feeler lever  38  such that said first striking feeler lever  38  comes into contact with the first second cam  34  at the end of the minute unit countdown when the display members for the hours, tens of minutes and minute units all display  0 . 
     More particularly, the third minute unit feeler lever  64  is a first arm of a detection lever  68  pivotally mounted at A, like the striking lever  41 . The detection lever  68  and the striking lever  41  are arranged to be capable of cooperating with each other. To this end, the detection lever  68  comprises, on said third minute unit feeler lever  64 , a pin  70  arranged to be in contact with the striking lever  41  and, for example, with its third arm  46 , such that a pivoting at A of one of the detection  68  and striking  41  levers leads to a pivoting at A of the other of the detection  68  and striking  41  levers. In particular, a pivoting at A of the detection lever  68  in the anticlockwise direction moves the pin  70  away from the striking lever  41  such that said striking lever  41 , released, can for its part pivot in the anticlockwise direction. 
     The striking-mechanism also comprises a third tens of minutes cam  72  associated with the third tens of minutes display member  18 , and a fourth tens of minutes feeler lever  74  arranged to be capable of cooperating with said third tens of minutes cam  72 , said third tens of minutes cam  72  being programmed to indicate the end of the tens of minutes countdown to the fourth tens of minutes feeler lever  74 . To this end, the tens of minutes cam  72  has a substantially circular profile and can include, for example, two opposite notches  76  when the third tens of minutes display member  18  is arranged to make one revolution, with the tens of minutes cam  72 , in two hours. The tens of minutes cam  72  can include only one notch  76  if the third tens of minutes display member is arranged to make one revolution per hour. The fourth tens of minutes feeler lever  74  is arranged to be positioned in one of the notches  76  when the display members for the hours  20  and tens of minutes  18  both display  0 , that is to say as of the moment when there is less than ten minutes to be counted down. 
     Furthermore, the fourth tens of minutes feeler lever  74  is arranged to cooperate with the third minute unit feeler lever  64  such that said third minute unit feeler lever  64  comes to cooperate with the second minute unit cam  62  at the end of the tens of minutes countdown when the hour display member  20  and the tens of minutes display member  18  both display  0 . 
     More particularly, the fourth tens of minutes feeler lever  74  is a second arm of the detection lever  68  opposite the third minute unit feeler lever  64  with respect to A such that a pivoting at A in the anticlockwise direction of the fourth tens of minutes feeler lever  74 , falling into one of the notches  76  of the tens of minutes cam  72 , leads to a pivoting at A, in the anticlockwise direction, of the third minute unit feeler lever  64  in order to come into contact with the minute unit cam  62 . 
     The striking-mechanism also comprises a fourth hour cam  78  associated with the fourth hour display member  20 , superposed on the third tens of minutes cam  72 , and a fifth hour feeler lever  80 , superposed on the fourth tens of minutes feeler lever  74 , and arranged to be capable of cooperating with said fourth hour cam  78 , said fourth hour cam  78  being programmed to indicate the end of the hour countdown to the fifth hour feeler lever  80 . To this end, the fourth hour cam  78  has a substantially circular profile and includes a notch  82  (cf.  FIGS.  4  and  5   ), the fifth hour feeler lever  80  being arranged to be positioned in the notch  82  when the hour display member  20  displays  0 , that is to say as of the moment when there is less than an hour to be counted down. 
     The fourth hour display member  20  can be arranged to turn with the fourth hour cam  78  in such a way as to make it possible to count down six hours per revolution. The number of hours counted down can be different depending on the arrangement of the hour display member  20 . 
     Furthermore, the fifth hour feeler lever  80  is arranged to cooperate with the fourth tens of minutes feeler lever  74  such that said fourth tens of minutes feeler lever  74  comes to cooperate with the third tens of minutes cam  72  at the end of the hour countdown when the hour display member  20  displays  0 . 
     More particularly, the fifth hour feeler lever  80  is a third arm of the detection lever  68  such that a pivoting at A in the anticlockwise direction of the fifth hour feeler lever  80 , falling into the notch  82  of the hour cam  78 , leads to a pivoting at A, in the anticlockwise direction, of the fourth tens of minutes feeler lever  74  in order to come into contact with the tens of minutes cam  72 . 
     This means that, in this particularly preferred variant of the invention, the third minute unit feeler lever  64 , the fourth tens of minutes feeler lever  74  and the fifth hour feeler lever  80  form a single lever, namely the detection lever  68 . It is obvious that other arrangements of these levers are possible, selected such that said levers pivot in the same direction. In particular, the different feeler levers can be separated while being arranged so that when one pivots in one direction, the others pivot in the same direction. 
     All the elements such as return-bars, levers, controls, clamps, hooks of the different mechanisms described above are subject to their own return springs (not shown). 
     The operation of the movement is as follows: the initial STOP position in which the control device  12  is ready to operate is shown in  FIG.  1   . The secondary control  15  and the locking mechanism are in the locked state, the locking hook  22  being coupled to the hook  15   b  of the secondary control  15 . The secondary control  15  is therefore locked in rotation with the main control  13 , the elastic member connecting them being wound. In this STOP position, the countdown chronograph mechanism and the striking-mechanism are inactive. It is considered that the different display members for the hours  20 , tens of minutes  18 , minute units  16  and seconds have been positioned in order to display the predetermined time interval for the countdown. Only the seconds-wheel  4  of the base timepiece movement turns. 
     With reference to  FIG.  2   , the control member  11  of the control device  12  is pushed by a user in order to trigger the START such that the column wheel  14  turns in such a way as to open the clutch control clamp  8  and the clutch clamp  10  in order to engage the seconds-wheel  4  and the chronograph drive wheel and pinion  1 . The opening of the clutch clamp  10  releases the striking lever  41  and the end of striking lever  50 , their respective arms  46  and  60  no longer being retained by the pin  48  of the clutch clamp  10 . The striking lever  41  pivots around A in the anticlockwise direction, making it possible for the detection lever  68  to pivot in the anticlockwise direction, such that the first striking feeler lever  38 , the third minute unit feeler lever  64 , and the fourth tens of minutes feeler lever  74 , which were at a distance from their respective cams  34 ,  62 ,  72  in order to make it possible to adjust the display members  16 ,  18  for the countdown, pivot in the anticlockwise direction and slightly approach their respective cams  34 ,  62 ,  72 . The fifth hour feeler lever  80 , which was also at a distance from its hour cam  78  in order to make it possible to adjust the hour display member  20  for the countdown, pivots in the anticlockwise direction until it comes into contact with its hour cam  78 . 
     Similarly, the released end of striking lever  50  pivots around B in the anticlockwise direction such that the second end of striking feeler lever  40  also slightly approaches the second cam  34 . The end of striking lever  50  is held in position by the foot  46   b  of the third arm  46  of the striking lever  41  resting on the first beak  60   a  of its third arm  60 . 
     The chronograph drive wheel and pinion  1 , engaged with the seconds-wheel  4 , drives the drive wheel  2  and the first second cam  34  in the anticlockwise direction. The display members for the hours  20 , tens of minutes  18  and minute units  16  are also driven with, respectively, the hour cam  78 , the tens of minutes cam  72  and the minute unit cam  62  each time the seconds-hand carried by the drive wheel  2  moves to  0 . 
     With reference to  FIG.  3   , the START phase is terminated by the return of the control member  11  to its initial position as a result of the action of its return spring (not shown). The countdown is in progress. The drive wheel  2  and the second cam  34  turn in the anticlockwise direction such that the display members for the hours  20 , tens of minutes  18  and minute units  16  with their respective cams  62 ,  72 ,  78  are released and can turn, depending on the countdown to be displayed, each time the seconds-hand moves to  0 , as in a standard countdown. The fifth hour feeler lever  80  is in contact with its hour cam  78 , the other feeler levers  38 ,  40 ,  64  and  74  remaining at a distance from their cams  34 ,  62 ,  72 . 
     With reference to  FIG.  4   , when there is less than an hour to be counted down, the hour display member  20  is positioned in order to display  0  such that the hour feeler lever  80 , being in contact with the hour cam  78 , engages in the notch  82  of said hour cam  78  by pivoting at A in the anticlockwise direction. The pivoting of the hour feeler lever  80  means the pivoting at A in the anticlockwise direction of the detection lever  68  and, therefore, of the tens of minutes feeler lever  74  which comes into contact with the tens of minutes cam  72  and the minute unit feeler lever  64  which approaches its cam  62 , as well as the pivoting at A in the anticlockwise direction of the striking lever  41  and, therefore, of the striking feeler lever  38  which approaches the second cam  34 . The countdown continues via the drive wheel  2  driven by the chronograph drive wheel and pinion  1 . 
     With reference to  FIG.  5   , when there are less than ten minutes to be counted down, the hour display member  20  still displaying  0 , the tens of minutes display member  18  is positioned in order to display  0  such that the tens of minutes feeler lever  74 , being in contact with the tens of minutes cam  72 , engages in the notch  76  of said tens of minutes cam  72  by pivoting at A in the anticlockwise direction. The pivoting of the tens of minutes feeler lever  74  means the pivoting at A in the anticlockwise direction of the detection lever  68  and, therefore, of the minute unit feeler lever  64  which comes into contact with the minute unit cam  62 , as well as the pivoting at A in the anticlockwise direction of the striking lever  41  and, therefore, of the striking feeler lever  38  which approaches the second cam  34 . The hour display member  20  having remained in the position displaying  0 , the hour feeler lever  80  remains engaged in the notch  82  of the hour cam  78 . The countdown continues via the drive wheel  2  driven by the chronograph drive wheel and pinion  1 . 
     With reference to  FIG.  6   , when there is less than a minute to be counted down, the display members for the hours  20  and tens of minutes  18  still displaying  0 , the minute unit display member  16  is positioned in order to display  0  such that the minute unit feeler lever  64 , being in contact with the minute unit cam  62 , engages in the notch  66  of said minute unit cam  62  by pivoting at A in the anticlockwise direction. The pivoting of the minute unit feeler lever  64  means the pivoting at A in the anticlockwise direction of the detection lever  68  and, therefore, the pivoting at A in the anticlockwise direction of the striking lever  41  and, therefore, of the striking feeler lever  38  which comes into contact with the second cam  34  linked to the drive wheel  2 . The display members for the hours  20  and tens of minutes  18  having remained in the position displaying  0 , the hour feeler lever  80  remains engaged in the notch  82  of the hour cam  78 , and the tens of minutes feeler lever  74  remains engaged in the notch  76  of the tens of minutes cam  72 . With the pivoting of the striking lever  41  and its arm  42 , the stopping of striking lever  44  is arranged to start to free itself from the stopping star  32  by pivoting in the clockwise direction around its pivot D, and the foot  46   b  of the third arm  46  of the striking lever  41  is practically freed from the first beak  60   a  of the third arm  60  of the end of striking lever  50 . The countdown continues via the drive wheel  2  driven by the chronograph drive wheel and pinion  1  such that the second display member continues to turn in the anticlockwise direction with the second cam  34 . 
     With reference to  FIG.  7   , the display members for the hours  20 , tens of minutes  18  and minute units  16  still displaying  0 , when the second display member displays the specified time before the end of the countdown, for example 20 seconds, the second cam  34  is positioned such that the beak  38   a  of the striking feeler lever  38 , being in contact with the second cam  34 , engages in the start  36   a  of the notch  36  of said second cam  34  by pivoting at A in the anticlockwise direction. The pivoting of the striking feeler lever  38  means the pivoting at A in the anticlockwise direction of the striking lever  41  and, in particular, of its arm  42  such that the stopping of striking lever  44  frees itself from the stopping star  32  by pivoting in the clockwise direction around its pivot D, and releases it. The element  30  of the striking geartrain being released, the striking-mechanism starts striking at the specified time before the end of the countdown. 
     Thus, the pivoting in the anticlockwise direction of the hour feeler lever  80 , then of the tens of minutes feeler lever  74 , then of the minute unit feeler lever  64 , when it engages in the notch of its respective cam means the pivoting at A of the detection  68  and striking levers  41  assembly in the anticlockwise direction such that said feeler levers gradually approach their respective cams until they come into contact with their respective cams in order to be capable of engaging in the associated notch when their respective display members display zero, and such that the striking feeler lever  38  also gradually approaches the second cam  34  until it comes into contact with said second cam  34  in order to be capable of falling into the notch  36  when the countdown reaches the specified time before the end of the countdown in order to trigger the striking. 
     In parallel, the third arm  46  of the striking lever  41  has also pivoted at A such that its foot  46   b  frees itself completely from the first beak  60   a  of the third arm  60  of the end of striking lever  50 . The end of striking lever  50  is then released and pivots in the anticlockwise direction around B such that the beak  40   a  of the end of striking feeler lever  40  comes into contact with the second cam  34 . 
     The display members for the hours  20 , tens of minutes  18  and minute units  16  having remained in the position displaying  0 , the hour feeler lever  80  remains engaged in the notch  82  of the hour cam  78 , the tens of minutes feeler lever  74  remains engaged in the notch  76  of the tens of minutes cam  72 , and the minute unit feeler lever  64  remains engaged in the notch  66  of the minute unit cam  62 . The countdown continues via the drive wheel  2  driven by the chronograph drive wheel and pinion  1  such that the second display member continues turning in the anticlockwise direction with the second cam  34 . 
     With reference to  FIG.  8   , when the countdown ends and reaches zero, the display members for the hours  20 , tens of minutes  18  and minute units  16  still displaying  0 , the second display member is positioned with the second cam  34  in order to display  0 , the striking still being in progress. The circular length of the notch  36  of the second cam  34  is such that when the  0  is displayed at the end of the countdown, the beak  40   a  of the end of striking feeler lever  40 , being in contact with the second cam  34 , engages in the start  36   a  of the notch  36  of said second cam  34  by pivoting at B in the anticlockwise direction. The beak  38   a  of the striking feeler lever  38  has reached the end  36   b  of the notch  36 . 
     The pivoting of the end of striking feeler lever  40 , having fallen into the notch  36  of the second cam  34  at the end of the countdown, means the pivoting at B in the anticlockwise direction of the end of striking lever  50  and, in particular, of its arm  54  such that the hook  56  carried by the arm  54  releases the control lever  19  in order to act on the control device  12  in order to control a rotation of the column wheel  14  in order to disengage the clutch device  6 . 
     With reference to  FIG.  9   , the control lever  19 , released, pivots sufficiently so that its pin  23  comes, during its travel, to cooperate with the locking hook  22  in such a way as to cause it to pivot in the anticlockwise direction. The locking hook  22  having separated from the hook  15   b  of the secondary control  15  then passes to the unlocked state. The secondary control  15  is then also in the unlocked state, disconnected from the main control  13  such that, thanks to the energy supplied by the elastic member which is unwinding, said secondary control  15 , released, only pivots in the clockwise direction by activating, by its hook  15   a,  the first drive wheel  14   a  of the column wheel  14  in the anticlockwise direction. This corresponds to an automatic STOP, during the course of which the column wheel  14  is actuated automatically solely by the secondary control  15 , the main control  13  and the second drive wheel  14   c  having remained stationary, and the elastic coupling element between the two drive wheels  14   a,    14   c  having disengaged. 
     The rotation of the column wheel  14  controls the closing of the clutch clamps  8  and  10  in such a way as to disengage the seconds-wheel  4  and the chronograph drive wheel and pinion  1 , which leads to the stopping of the drive wheel  2  and the second cam  34 . During the closing of the clutch clamp  10 , the pin  48  of said clutch clamp  10  returns to its initial position by resting on the heel  46   a  of the arm  46  of the striking lever  41  and on the beak  60   b  of the arm  60  of the end of striking lever  50 , such that said striking lever  41  and end of striking lever  50 , and more particularly the striking feeler lever  38  and the end of striking feeler lever  40 , pivot respectively at A and B in the clockwise direction and are freed from the second cam  34 . With this pivoting of the striking lever  41 , and therefore of its arm  42 , at the same time as the disengagement of the chronograph mechanism, the stopping of striking lever  44  pivots in the anticlockwise direction around its pivot D in order to again come to cooperate with the stopping star  32  and to stop the element  30  of the striking geartrain. Thus, the striking is stopped at the same time as the end of the countdown. 
     For a next countdown, the display members  16 ,  18 ,  20  will again be positioned depending on the predetermined time interval for the countdown and the control device  12  is arranged to be positioned in a position ready to operate at the time of the next START. More particularly here, the automatic function of the secondary control  15  is made operational again for the next use of the chronograph, thanks to the locking mechanism passing into its locking position when the next START is triggered after the user again presses the control member  11 , before returning to the locked state. Indeed, when a user triggers a new START, the secondary control  15  being in its unlocked state, only the main control  13  tilts in order to actuate the column wheel  14 , its hook  13   a  actuating the second drive wheel  14   c,  itself driving the first drive wheel  14   a,  and therefore the columns  14   b,  via the coupling produced by the elastic coupling element, as described above, in order to control a new opening of the clamps  8  and  10 . 
     In parallel, by tilting, the main control  13  makes it possible to rewind the elastic member connecting it to the secondary control  15 . On the other hand, when the main control  13  tilts, its pin  21  comes, during its travel, to cooperate with the control lever  19  in such a way as to cause it to pivot into the locking position, retracting the hook  56 . When it is pivoted, the control lever  19  is rewound. At the same time, the locking hook  22 , embedded in the main control  13 , comes back into contact with the hook  15   b  of the secondary control  15 , causing it to be freed in the anticlockwise direction in order to pass into the locking position. At the end of the tilting of the main control  13 , the locking hook  22  returns to engage in the hook  15   b  of the secondary control  15  in order to pass into the locked state again. The elastic member between the main control  13  and the secondary control  15  is completely rewound. 
     It is of course possible to make a STOP &amp; START during the countdown. 
     It is possible to provide a similar mechanism by removing the display of the hours and the elements linked to the hour countdown if only a countdown of the minutes and seconds is desired. 
     It is also possible, according to another embodiment, to not count down the seconds and to have a first display member arranged to display a minute unit countdown, the first cam  34  linked to the first display member then being arranged to make one revolution in ten minutes and the circular length of its notch being able to be selected in order to trigger the striking a few minutes before the end of the countdown. 
     In this case, it is considered that the first and second display members coincide, the first and second cams coincide and a third tens of minutes display member is provided, which is arranged to display the tens of minutes countdown as described above. The striking-mechanism then comprises a third tens of minutes cam associated with said third tens of minutes display member, and a fourth tens of minutes feeler lever arranged to be capable of cooperating with said third tens of minutes cam, said third tens of minutes cam being programmed to indicate the end of the tens of minutes countdown to the fourth tens of minutes feeler lever, said fourth tens of minutes feeler lever being arranged to cooperate directly with the first striking feeler lever, coincides with the minute unit feeler lever such that said first striking feeler lever comes to cooperate with said first cam at the end of the tens of minutes countdown. The rest of the mechanism is identical to that described above. 
       FIG.  10    shows a variant of the movement according to the invention, in which the first striking feeler lever  38 , the third minute unit feeler lever  64 , the fourth tens of minutes feeler lever  74  and the fifth hour feeler lever  80  form one single lever. 
     The first striking feeler lever  38  is also rigidly connected to two other arms, not shown, corresponding to the arms  42  and  46  of the first example such that the entire assembly can form one single lever. 
     The functional elements identical to the elements of the movement in  FIG.  1    are shown with the same reference numerals. 
     In the variant shown in  FIG.  10   , the second cam  34  linked to the second display member and to the drive wheel  2  is provided. The second cam  34  comprises the notch  36  defining the specific striking time before the end of the countdown. The minute unit display member  16  associated with the minute unit cam  62  including its notch  66 , the tens of minutes display member  18  associated with the tens of minutes cam  72  including its two notches  76 , and the hour display member  20  associated with the hour cam  78  including its notch  82 , are also provided. 
     The hour feeler lever  80  is arranged to be capable of cooperating with the hour cam  78  and of falling into the notch  82  when the hour display member  20  displays zero. Said hour feeler lever  80  carries, on its arm, the tens of minutes feeler lever  74 , disposed substantially perpendicular to the hour feeler lever  80 . The tens of minutes feeler lever  74  carries, at its end, a pin  75  arranged to come into contact substantially tangentially with the tens of minutes cam  72  and to fall into one of the notches  76  when the tens of minutes display member  18  displays zero. The minute unit feeler lever  64  is arranged to be capable of cooperating with the minute unit cam  62  and of falling into the notch  66  when the minute unit display member  16  displays zero. The striking feeler lever  38  is arranged to be capable of cooperating with the second cam  34  and of falling into the notch  36  when the countdown reaches the specified time before the end of the countdown in order to trigger the striking. 
     The striking feeler lever  38 , the minute unit feeler lever  64  and the hour feeler lever  80  are rigidly connected to each other by their opposite ends to their feelers in such a way as to form the different arms of one single lever pivotally mounted at A. Thus, as described above, the pivoting in the anticlockwise direction of the hour feeler lever  80 , then of the tens of minutes feeler lever  74 , then of the minute unit feeler lever  64 , when it engages in the notch of its respective cam means the pivoting of the lever assembly in the anticlockwise direction such that said feeler levers gradually approach their respective cams until they come into contact with their respective cams in order to be capable of engaging in the associated notches when their respective display members display zero, and such that the striking feeler lever  38  also gradually approaches the second cam  34  until it comes into contact with said second cam  34  in order to be capable of falling into the notch  36  when the countdown reaches the specified time before the end of the countdown in order to trigger the striking. 
     The end of striking lever (not shown) is identical to the lever  50  of the first example. 
     In another embodiment of the invention according to  FIGS.  12  to  21   , the chronograph mechanism is arranged so that the first second display member, that is to say the chronograph seconds-hand, continues turning after the automatic stopping of the striking and after the end of the countdown of the predetermined time interval. 
     The elements common to the embodiment in  FIGS.  1  to  9    are shown with the same reference numerals. 
     Said chronograph drive wheel and pinion  1  is arranged to be capable of being kinematically connected to the seconds-wheel  4  of the base timepiece movement indicating the current time by the vertical clutch device  6 . Said vertical clutch device  6  comprises a clutch control clamp  8  and a clutch clamp  10  arranged to move apart when the chronograph is activated in order to launch a countdown in such a way as to engage the seconds-wheel  4  and the chronograph drive wheel and pinion  1 . The opening of the clamps  8  and  10  is controlled in the traditional manner by a standard control device with a column wheel  14 , actuated for example by a button of the push-piece  11  type, in order to carry out the start/stop control of the chronograph mechanism manually and in the conventional manner. 
     The display means arranged to display the hour, tens of minutes and minute units remaining until the end of the countdown of the predetermined time interval are similar to those described previously. 
     Only the minute unit cam  62  with its notch  66 , associated with the minute unit display member, the minute unit feeler lever  64  mounted pivotally at G, the tens of minutes cam  72  with its notches  76 , associated with the tens of minutes display member, the tens of minutes feeler lever  74 , the hour cam  78  with its notch  82 , associated with the hour display member, superposed on the tens of minutes cam  72 , and the hour feeler lever  80 , superposed on the tens of minutes feeler lever  74 , are shown. 
     The tens of minutes feeler lever  74  and the hour feeler lever  80  form the arms of a detection lever  90  pivotally mounted at H, as in the case of the detection lever  68  of the first embodiment. In this embodiment, the detection lever  90  comprises a third arm  92  opposite the tens of minutes feeler lever  74  with respect to H, such that a pivoting at H in the clockwise direction of the tens of minutes feeler lever  74 , falling into one of the notches  76  of the tens of minutes cam  72 , leads to a pivoting at H, in the clockwise direction, of the third arm  92  of the detection lever  90 . At the end of the third arm  92  of the detection lever  90 , there is provided a pin  94  which is arranged to cooperate with a beak  96  of the minute unit feeler lever  64 . Thus, a pivoting at H in the clockwise direction of the detection lever  90  and its arm  92  leads to a pivoting at G, in the anticlockwise direction, of the third minute unit feeler lever  64  in order to come into contact with the minute unit cam  62 . 
     As in the first embodiment above, the minute unit feeler lever  64  is arranged to be positioned in the notch  66  of the minute unit cam  62  when the display members for the hours, tens of minutes and minute units all display  0 , that is to say as of the moment when there is less than a minute to be counted down. 
     The striking-mechanism comprises the first second cam  34 . In this embodiment, the construction of the mechanism is realized such that the first second cam  34  and the first display member for displaying a second countdown, that is to say the chronograph seconds-hand, are carried directly by the axis of the chronograph drive wheel and pinion  1 . 
     With reference to  FIG.  12   , the second cam  34  comprises the notch  36 , the circular length of which corresponds to the specified time of the striking before the end of the countdown of the predetermined time interval, the start of the notch  36  corresponding to the triggering of the striking, and the end of the notch  36  corresponding to the stopping of the striking. For example, the length of the notch  36  can correspond to a time of 20 seconds before the end of the countdown of said predetermined time interval. 
     The striking-mechanism also comprises a first striking lever  100  pivotally mounted at A and comprising a first arm made up of the first striking feeler lever  38  arranged to be capable of cooperating with the first cam  34  and the striking geartrain in order to trigger the striking at the start of the specified time before the end of the countdown of said predetermined time interval. 
     More specifically, the first striking feeler lever  38  has a beak  38   a  arranged to be capable of coming into contact with the first second cam  34 , then of engaging in its notch  36  at the moment of the striking. The striking lever  100  is subject to its spring  101 . 
     As in the first embodiment, said striking lever  100  comprises a second arm  42  arranged to control the stopping of striking lever  44  pivotally mounted at D, a pin  43  rigidly connected to the second arm  42  providing the link with said lever  44  via an oblong opening  45 , said stopping of striking lever  44  itself being arranged to be capable of cooperating with the stopping star  32  of the striking geartrain. 
     The striking lever  100  comprises a third arm  102  carrying a pin  104  arranged to be capable of cooperating with the clutch control clamp  8 . More specifically, the clutch control clamp  8  rests on the pin  104  when it is in a closed position. 
     Furthermore, the third minute unit feeler lever  64  is arranged to cooperate with the first striking feeler lever  38 , via the third arm  102  of the striking lever  100 , such that the beak  38   a  of the first striking feeler lever  38  comes into contact with the first second cam  34  at the end of the minute unit countdown when the display members for the hours, tens of minutes and minute units all display  0 . 
     More particularly, the minute unit feeler lever  64  includes a foot  64   a  arranged in order to rest on a beak  106  of the third arm  102  of the striking lever  100  in such a way as to retain the first striking feeler lever  38  at a distance from the second cam  34  until the end of the minute unit countdown. 
     The striking lever  100  comprises a fourth arm  108  arranged to be capable of cooperating with the end of striking mechanism in order to control the automatic stopping of the striking at the end of said specified time at the same time as the end of the countdown of said predetermined time interval. 
     To this end, the end of striking mechanism comprises an end of striking lever  110  pivotally mounted at E, and arranged to cooperate with the first striking lever  100 . More specifically, the end of striking lever  110  comprises a first arm  111  terminated by a beak  112  and carrying a pin  113  arranged to cooperate with the end  114  in the form of a hook of the fourth arm  108  of the first striking lever  100 . The end of striking lever  110  comprises a second arm  115  arranged to cooperate with a pin  116  carried by the clutch clamp  10 . The end of striking lever  110  is subject to its spring  118 . 
     The end of striking mechanism also comprises a stopping of striking cam  120  kinematically linked to said chronograph drive wheel and pinion  1  and arranged to control the end of striking lever  110 , and therefore the first striking lever  100 , in order to automatically stop the striking at the end of the countdown of said predetermined time interval, and does so without disconnecting the clutch device  6 . 
     Advantageously, the stopping of striking cam  120  is coaxial to the second cam  34  and constrained to rotate with the latter. It comprises a beak  120   a.    
     In order to be capable of controlling the end of striking lever  110  via the stopping of striking cam  120  in order to automatically stop the striking, the end of striking mechanism comprises a lever hook  122  mounted pivotally at F, its pivot axis passing through the striking lever  100  by means of an opening provided for this purpose. Said lever hook  122  comprises a first arm  124  arranged to be capable of cooperating with the beak  120   a  of the stopping of striking cam  120  and a pin  126  arranged to cooperate with the fourth arm  108  of the first striking lever  100  in order to cause the lever hook  122  to pivot at F in such a way as to position its arm  124  in the radius of gyration of the beak  120   a  of the stopping of striking cam  120  when the first striking lever  100  pivots at A in the anticlockwise direction in order to bring the beak  38   a  of the first striking feeler lever  38  into contact with the first second cam  34 . 
     The lever hook  122  comprises a second arm  128  in the form of a hook arranged to cooperate with the beak  112  of the end of striking lever  110  in order to lock said end of striking lever  110  and to be capable of releasing it when said lever hook  122  is actuated by the stopping of striking cam  120 . 
     The lever hook  122  is subject to its spring  130 . 
     The operation of the mechanism according to this embodiment is as follows: the initial STOP position in which the countdown chronograph mechanism and the striking-mechanism are inactive is shown in  FIG.  12   . It is considered that the different display members for the hours, tens of minutes, minute units and seconds have been positioned to display the predetermined time interval for the countdown. Only the seconds-wheel  4  of the base timepiece movement turns. 
     The control member of the control device is pushed by a user in order to trigger the START such that the column wheel  14  turns in such a way as to open the clutch control clamp  8  and the clutch clamp  10  in order to engage the seconds-wheel  4  and the chronograph drive wheel and pinion  1 . 
     When the clutch clamp  10  is opened, its pin  116  resting on the second arm  115  of the end of striking lever  110  causes said end of striking lever  110  to resume its initial position such that it is locked in position by the lever hook  122 . 
     The opening of the clutch control clamp  8  releases the striking lever  100 , its third arm  102  no longer being retained by the clamp  8  until it then rests on the pin  104 . 
     As in the first embodiment, the striking lever  100  pivots around A in the anticlockwise direction such that the first striking feeler lever  38 , as well as the minute unit feeler lever  64 , and the other feeler levers for the tens of minutes and hours, which were at a distance from their respective cams in order to make it possible to adjust the display members for the countdown, pivot in order to slightly approach their respective cams. However, said striking lever  100  is kept away from the second cam  34  by the foot  64   a  of the minute unit feeler lever  64  resting on the beak  106  of the third arm  102  of the striking lever  100 . 
     The countdown is carried out in the same way as that described above for the first embodiment, the chronograph drive wheel and pinion  1 , engaged with the seconds-wheel  4 , picking up the first second cam  34  and the stopping of striking cam  120  in order to cause them to turn in the anticlockwise direction. The display members for the hours, tens of minutes and minute units are also driven with their respective cams each time the seconds-hand carried by the chronograph drive wheel and pinion  1  moves to  0 . The pivoting at H in the clockwise direction of the detection lever  90  and its arm  92  leads to a pivoting at G, in the anticlockwise direction, of the minute unit feeler lever  64  which gradually approaches the minute unit cam  62  until it comes into contact with the latter when there are less than ten minutes to be counted down. 
     With reference to  FIG.  13   , when there is one minute left to be counted down, the display members for the hours and tens of minutes display  0 , and the minute unit display member does not yet display  0  such that the minute unit feeler lever  64 , in contact with the minute unit cam  62 , is not yet engaged in the notch  66  of said minute unit cam  62 . In this position, the striking feeler lever  38  is still not in contact with the second cam  34 , the beak  106  of the third arm  102  of the striking lever  100  still being retained by the foot  64   a  of the minute unit feeler lever  64 . In this position, the striking lever  100 , by its second arm  42 , keeps the striking geartrain stopped, the stopping of striking lever  44  being engaged in the stopping star  32 . 
     Moreover, the lever hook  122  is at a distance from the stopping of striking cam  120 . 
     With reference to  FIG.  14   , when there is less than a minute to be counted down, the display members for the hours and tens of minutes still displaying  0 , the minute unit display member is positioned in order to display  0  such that the minute unit feeler lever  64 , being in contact with the minute unit cam  62 , engages in the notch  66  of said minute unit cam  62  by pivoting at G in the anticlockwise direction. 
     By pivoting, the foot  64   a  of the minute unit feeler lever  64  releases the third arm  102  and, therefore, the striking lever  100  such that said striking lever  100 , as a result of the action of its spring  101 , pivots at A in the anticlockwise direction, the beak  38   a  of the striking feeler lever  38  then coming into contact with the maximum radius of the second cam  34  carried by the chronograph drive wheel and pinion  1 . 
     During the pivoting of the striking lever  100 , and therefore of its second arm  42 , the stopping of striking lever  44  is arranged to start to free itself from the stopping star  32  by pivoting in the clockwise direction around its pivot D. The countdown continues via the chronograph drive wheel and pinion  1  such that the second display member continues turning in the anticlockwise direction with the second cam  34 . 
     With reference to  FIG.  15   , the display members for the hours, tens of minutes and minute units still displaying  0 , when the second display member displays the specified time before the end of the countdown, for example 20 seconds, the second cam  34  is positioned such that the beak  38   a  of the striking feeler lever  38 , being in contact with the second cam  34 , engages in the notch  36  of said second cam  34 . On falling into the notch  36 , the striking feeler lever  38  again pivots at A in the anticlockwise direction. The pivoting at A of the striking feeler lever  38  means the pivoting at A in the anticlockwise direction of the striking lever  100  and, in particular, of its second arm  42  such that the stopping of striking lever  44  frees itself from the stopping star  32  by pivoting in the clockwise direction around its pivot D, and releases it. The striking geartrain being released, the striking-mechanism starts striking at the specified time before the end of the countdown. 
     In parallel, the fourth arm  108  of the striking lever  100  has also pivoted in the anticlockwise direction such that it leads to the tilting of the lever hook  122 , via its pin  126 , in the clockwise direction around its pivot F so that its arm  124  enters the radius of gyration of the beak  120   a  of the stopping of striking cam  120  carried by the chronograph drive wheel and pinion  1 . 
     By pivoting at F in the clockwise direction, the arm  128  of the lever hook  122  has slightly freed itself from the beak  112  of the end of striking lever  110 . 
     With reference to  FIG.  16   , when the countdown ends and virtually reaches zero, for example 5 seconds before the end of the countdown, the second display member is positioned with the second cam  34  and the stopping of striking cam  120  in order to display for example 5, the striking still being in progress. The positioning of the beak  120   a  of the stop cam  120  is such that said beak  120   a  enters into contact with the arm  124  of the lever hook  122  in order to be capable of driving it in rotation at F in the clockwise direction. 
     The beak  38   a  of the striking feeler lever  38  has reached the end of the notch  36 . 
     With reference to  FIG.  17   , when the countdown ends and reaches zero, the display members for the hours, tens of minutes and minute units still displaying  0 , the second display member is positioned with the second cam  34  and the stopping of striking cam  120  in order to display  0 . 
     The lever hook  122  and the beak  120   a  of the stopping of striking cam  120  are configured so that, when  0  is displayed at the end of the countdown, the lever hook  122  controlled by the stopping of striking cam  120  has tilted at F in the clockwise direction sufficiently so that its arm  128  releases the beak  112  of the stopping of striking lever  110 . 
     The end of striking lever  110  is then released and pivots at E in the anticlockwise direction, as a result of the action of its spring  118 . 
     The pivoting of the end of striking lever  110  at the end of the countdown means the pivoting in the anticlockwise direction of its first arm  111 , such that the pin  113  carried by said arm  111  drives the end in the form of a hook  114  of the fourth arm  108  of the striking lever  100  in order to cause said striking lever  100  to pivot at A in the clockwise direction. This pivoting of the striking lever  100  at A in the clockwise direction makes it possible to free the striking feeler lever  38  from the second cam  34 . In parallel, during this pivoting at A of the striking lever  100  in the clockwise direction, and therefore of its arm  42 , at the same time as the end of the countdown, the stopping of striking lever  44  is driven by the arm  42  in order to pivot in the anticlockwise direction around its pivot D in order to again come to cooperate with the stopping star  32  and to stop the striking geartrain. Thus, the striking is stopped at the same time as the end of the countdown. 
     With reference to  FIG.  18   , once the striking has stopped, the second display member, that is to say the chronograph seconds-hand, continues its travel with the second cam  34  and the stopping of striking cam  120  in the anticlockwise direction such that the beak  120   a  of said stopping of striking cam  120  passes the arm  124  of the lever hook  122  and releases it. Once released, the lever hook  122  pivots at F in the anticlockwise direction, as a result of the action of its spring  130 , until its second arm  128  in the form of a hook comes to rest on the arm  111  of the end of striking lever  110 . Thus, the lever hook  122  exits the radius of gyration of the stopping of striking cam  120 , which makes it possible to avoid any unnecessary energy consumption when the seconds-hand continues its travel while waiting for a manual stoppage of the chronograph mechanism. 
     With reference to  FIGS.  19  and  20   , when the user manually stops the chronograph mechanism in order to stop the seconds-hand, he presses the control member of the chronograph mechanism in order to trigger the STOP such that the column wheel  14  turns in such a way as to close the clutch control clamp  8  and the clutch clamp  10  in order to disengage the clutch device  6  in order to disengage the seconds-wheel  4  and the chronograph drive wheel and pinion  1 . As illustrated in  FIG.  19   , when the clutch clamp  10  which was in the open position closes, it pivots in the clockwise direction such that its pin  116  drives the second arm  115  of the end of striking lever  110  in such a way as to cause said end of striking lever  110  to pivot at E in the clockwise direction, and also the lever hook  122  resting on said end of striking lever  110 . 
     When the clamps  8 ,  10  are closed as illustrated in  FIG.  20   , the end of striking lever  110 , having completed its travel, remains held by the pin  116  of the clutch clamp  10 . The end of striking lever  110  will be locked by the arm  128  of the lever hook  122  resuming its initial position by pivoting at F in the anticlockwise direction as a result of the action of its spring  130  when the striking lever  100 , released by the opening of the clutch control clamp  8  during the next start of countdown, pivots at A in the anticlockwise direction as a result of the action of its spring  101 . 
     It is of course possible to make a STOP, for example during the countdown and the striking, the mechanism then being in a configuration similar to that of  FIG.  15  or  16   . In this configuration, the clutch control clamp  8  is not in contact with the striking lever  100  since it is in the open position and does not rest on the pin  104  of the third arm  102  of the striking lever  100 . With reference to  FIG.  21   , when the user stops the countdown, the clamps  8  and  10  close, controlled by the column wheel  14 . The clutch control clamp  8  pivots in the anticlockwise direction in order to come to rest on the pin  104  of the third arm  102  of the striking lever  100  such that said striking lever  100  pivots at A in the clockwise direction. This pivoting of the striking lever  100  at A in the clockwise direction makes it possible to free the striking feeler lever  38  from the second cam  34 . In parallel, during this pivoting at A of the striking lever  100  in the clockwise direction, and therefore of its arm  42 , the stopping of striking lever  44  is driven by said arm  42  in order to pivot in the anticlockwise direction around its pivot D in order to again come to cooperate with the stopping star  32  and to stop the striking geartrain. Thus, the striking is stopped. During the next start of the countdown without a prior adjustment of the display members in order to display a countdown, the different parts will resume their position before the next STOP. 
     The present invention makes it possible to have a countdown chronograph mechanism equipped with a striking-mechanism which is triggered before the end of the countdown of a predetermined time interval at a predefined time before the end of the countdown in order to warn a user that the countdown in progress of said predetermined time interval is about to come to an end. Thus, the present invention makes it possible to have a countdown having a pre-alarm using a mechanical striking-mechanism, the end of the striking being synchronized with the end of the countdown of said predetermined time interval. According to the variants, the chronograph mechanism can stop at the end of the countdown of said predetermined time interval or remain activated such that the chronograph seconds-hand continues turning without triggering a striking.