EP3686694B1 - Alarm clock mechanism and timepiece comprising such a mechanism - Google Patents

Description

• un mécanisme de sonnerie ;
• un ressort-moteur agencé pour se désarmer en entraînant le mécanisme de sonnerie suite à un déclenchement de ce dernier ;
• un système de déclenchement comportant une came de déclenchement agencée pour être reliée à la roue des heures du mouvement par un premier train d'engrenages de manière à être entraînée en rotation autour d'un axe, dans un sens donné, au rythme d'un tour en douze ou en vingt-quatre heures, et agencée pour commander le déclenchement du mécanisme de sonnerie lorsqu'elle atteint une position angulaire prédéfinie ;
• un affichage agencé pour indiquer une heure de réveil programmée à laquelle la came de déclenchement devrait commander le déclenchement du mécanisme de sonnerie après avoir parcouru la distance angulaire séparant une position angulaire courante de la position angulaire prédéfinie ;
• un système de réglage de l'heure de réveil comportant un organe de commande actionnable manuellement et agencé pour commander l'affichage, et comportant également un deuxième train d'engrenages agencé pour relier l'affichage à la came de déclenchement, de sorte que le système de réglage de l'heure de réveil permette de modifier dans les deux sens la position angulaire courante de la came de déclenchement, tout en décalant l'heure de réveil programmée indiquée par l'affichage, le deuxième train d'engrenages étant en outre agencé de sorte que la roue des heures ne modifie pas l'affichage lorsqu'elle entraîne la came de déclenchement ;

le premier et le deuxième train d'engrenages comportant une partie commune directement en amont de la came de déclenchement, et les engrenages de la partie commune ayant un jeu de transmission cumulé susceptible de donner à la came de déclenchement un jeu angulaire suffisant pour engendrer un décalage sensible entre l'heure de réveil programmée et l'heure à laquelle la came de déclenchement atteint la position angulaire prédéfinie.The present invention relates to an alarm mechanism for a mechanical timepiece comprising:

• a striking mechanism;
• a mainspring arranged to disarm itself by driving the striking mechanism following a triggering of the latter;
• a trigger system comprising a trigger cam arranged to be connected to the hour wheel of the movement by a first gear train so as to be rotated around an axis, in a given direction, at the rate of a turn in twelve or twenty-four hours, and arranged to control the triggering of the striking mechanism when it reaches a predefined angular position;
• a display arranged to indicate a programmed wake-up time at which the trigger cam should command the triggering of the striking mechanism after having traveled the angular distance separating a current angular position from the predefined angular position;
• a system for setting the wake-up time comprising a control member which can be actuated manually and arranged to control the display, and also comprising a second gear train arranged to connect the display to the trigger cam, so that the alarm time setting system allows to modify in both directions the current angular position of the trigger cam, while shifting the programmed alarm time indicated by the display, the second gear train being furthermore arranged so that the hour wheel does not modify the display when it drives the trigger cam;

the first and the second gear train comprising a common part directly upstream of the trigger cam, and the gears of the common part having a cumulative transmission clearance capable of giving the trigger cam sufficient angular play to generate a significant offset between the programmed wake-up time and the time at which the trigger cam reaches the predefined angular position.

The present invention further relates to a mechanical timepiece comprising an alarm mechanism in accordance with the above definition.

PRIOR ART

Wake-up mechanisms are already known which comply with the definition given in the preamble. The patent document CH 703 615 B1 in particular describes a timepiece which comprises a mechanical movement and an alarm mechanism comprising a trigger cam driven in rotation by a trigger wheel which is itself kinematically connected to the hour wheel of the movement. This known wake-up mechanism also comprises a differential gear train of the type comprising a satellite and a planet carrier. The hour wheel is pivoted in the center of the movement and is kinematically connected to the planet carrier. The satellite is constituted by a mobile formed by a wheel and a pinion which are rotatably arranged on either side of the plate of the planet carrier so as to mesh respectively with an input mobile and an output mobile. arranged to rotate coaxially with the planet carrier. Finally, the output mobile is itself kinematically connected to the trigger wheel. The ratios of the gear train driving from the hour wheel of the movement to the trigger wheel of the alarm mechanism are such that the trigger cam is driven by the hour wheel so as to rotate in a given direction at the rate of one turn in 24 hours.

The alarm mechanism also includes an adjustment system allowing a user of the timepiece to set the alarm time. To this end, the movement winding stem is arranged to be kinematically connected to the input mobile of the differential gear when the stem is in a corrective position. Thus, when the time-setting crown is pulled into the second axial position and a user turns it, it drives the input mobile of the differential gear. As, for its part, the output mobile of the differential gear train is arranged to drive the trigger wheel, the wake-up mechanism makes it possible to modify the angular position of the trigger wheel and of the trigger cam using the time-setting crown. The alarm mechanism further comprises an indicator hand which is carried by the input mobile of the differential gear. This hand is arranged to move above a graduation of the dial of the timepiece to indicate the programmed alarm time. The gear ratios of the differential gear are such that the trigger cam can be driven synchronously with the indicator needle carried by the input mobile. The system for adjusting the alarm mechanism described in the aforementioned prior document therefore makes it possible to use the winding stem to modify the current angular position of the trigger cam, while consequently shifting the programmed alarm time indicated by the 'needle.

As already mentioned, the movement is arranged to rotate the trigger cam in a certain direction called the "given direction". Under these conditions, if the user also turns the trigger cam in the direction given by setting the alarm time using the crown, it causes a reduction in the angular distance separating the current angular position from the predefined angular position. This results in a reduction in the time that will be required for the cam to reach the predefined position once the user has released the crown. It will therefore be understood that when the current position of the triggering cam is adjusted by rotating it in said given direction, the wake-up time is brought closer, or in other words, the indicator hand is rotated with the wake-up time. programmed counterclockwise. Conversely, if the user sets the alarm time by rotating the trigger cam in the opposite direction to the said direction, it causes an increase in the distance. angular separating the current angular position from the predefined angular position. It will therefore be understood that when the current position of the tripping cam is adjusted by rotating it in the direction opposite to the direction given, the wake-up time is delayed. In other words, the hand indicating the programmed wake-up time is rotated clockwise.

It will also be understood that, in accordance with the definition given in the preamble, the alarm mechanism which has just been described comprises a first gear train which connects the hour wheel to the trigger cam and a second gear train which connects display to trigger cam. In addition, the first and second gear train have a common part located directly upstream of the trigger cam. This common part is formed of a first gear between the teeth of the differential gear output mobile and that of the trigger wheel, of a second gear between the teeth of the satellite wheel and that of the differential input mobile , and finally, a third gear between the toothing of the pinion of the satellite and that of the differential output mobile. Each of these gears is inevitably associated with a certain angular displacement, and this displacement contributes to an accumulated transmission play of the part common to the two sets of gears.

The cumulative transmission clearance can cause a significant difference between, on the one hand, the programmed wake-up time indicated by the hand, and on the other hand, the time at which the trigger cam actually reaches the predefined angular position. . Indeed, we have seen that, when a user uses the crown to turn the hand indicating the alarm time in a clockwise direction, the movement of the cog which constitutes the common part between the first and the second train of gears change direction. However, due to transmission play, the trip cam does not instantly start to rotate in the opposite direction to the given direction. On the contrary, it begins by coming to a standstill during the time necessary for the contact between the teeth to be reversed. The trigger cam therefore follows the movement of the indicator needle with a certain delay. It will be understood that because of this delay, the indicator hand displays a wake-up time later than the time at which the trigger cam should actually reach the predefined angular position given its current position. On the other hand, once the user releases the crown, having finished setting the alarm time, the hour wheel of the movement takes over. There is therefore a new reversal of the direction of travel. However, the trigger cam does not instantly resume rotating in the given direction. On the contrary, it remains motionless during the time necessary for the movement to bring the contact between the teeth back to the starting functional configuration. The tripping cam therefore begins to follow the movement of the hour wheel with a certain delay, and this delay corresponds to the time required for the transmission play to be taken up. It will also be understood that it is only once the triggering cam has started moving again, that the time at which the triggering cam should actually reach the predefined angular position, given its current position. , corresponds again to the wake-up time indicated by the indicator hand.

With a prior art wake-up mechanism like the one just described, it is impossible to select an imminent wake-up time when setting the programmed wake-up time by rotating the indicator hand forward. . In fact, if the time between the programmed alarm time and the current time is less than the time required for the movement to catch up with the transmission set, and the setting has been made forwards, the buzzer sounds immediately. , the instant the user has finished their adjustment. A known solution to this problem is to equip the alarm mechanism with an adjustment system allowing only the adjustment of the programmed wake-up time by rotating the indicator hand counterclockwise (backwards). This solution is not completely satisfactory, especially in the case of a wake-up mechanism programmed for 24 hours.

BRIEF PRESENTATION OF THE INVENTION

An aim of the present invention is to remedy the drawbacks of the prior art which have just been explained. The present invention achieves this and other object by providing a wake-up mechanism according to claim 1 appended hereto.

According to the invention, the mechanism comprises a play take-up cam mounted rigidly on the axis of rotation of the trigger cam, and a roller or a tilted back against the profile of the play take-up cam by the force of return of a spring. The caster or incline, on the one hand, and the play take-up cam, on the other hand, are further arranged to cooperate so that the force exerted by the caster or incline on the cam The backlash generates a torque capable of causing the latter to rotate. It will be understood that when the caster or the incline exerts a force on the play take-up cam, the latter exerts a force in reaction on the caster or the incline, and that it is this latter force which controls the winding of the. spring. The degree of winding of the spring is in fact a function of the distance up to which the play take-up cam has pushed the wheel or inclined it from its rest position. This distance itself depends in particular on the angular position of the play take-up cam and on the shape of its profile. It will also be understood that the force exerted by the caster or the incline on the play take-up cam is itself determined by the degree of winding of the spring. It will also be noted that, as the play take-up cam is rigidly fixed to the release cam, its angular position is entirely determined by that of the release cam, and vice versa.

Still according to the invention, the profile of the play take-up cam is designed so that, when the modulus of the angle separating the current angular position of the tripping cam from the predefined position is less than or equal to the play of cumulative transmission, the torque generated by the cooperation of the caster or the incline with the profile is oriented in the opposite direction direction given, and its intensity is sufficient to tension the gears of the common part to the first and second gear train. It will be understood that, in general, the direction of the torque to which the play take-up cam is subjected is determined by the sign of the angle existing between, on the one hand, a radius of the play-take-up cam passing through its point of contact with the roulette or with the incline, and on the other hand, the direction of the force that the roulette or incline exerts on the take-up cam. Thus, like the force that the roulette or the incline inclined exerted on the play take-up cam is normally oriented perpendicular to the profile of the play take-up cam at the point of contact, it will be understood that the direction of the torque is determined by the sign of the slope of the profile of the take-up cam. play at the point of contact with the roulette wheel or the incline. In other words, when, by turning in one direction, the play take-up cam pushes the roller or the incline so that it deviates from the axis, the torque generated is oriented in the opposite direction to the direction of rotation. Whereas, when turning in one direction, the play take-up cam allows the caster or incline to lower so that it approaches the axis, the torque generated is oriented in the directions. of rotation. We can also specify that the intensity of the torque generated depends on the one hand on the force exerted by the spring, and on the other hand, on the modulus of the slope of the profile at the point of contact between the play take-up cam and the roulette or inclined.

It will also be understood that when the modulus of the angle which separates the current angular position of the triggering cam from its predefined position is greater than the cumulative transmission clearance, neither the direction nor the intensity of the torque generated by the cooperation of the profile of the play take-up cam with the roulette wheel or the incline is not decisive as regards the operation of the invention. In other words, the invention does not impose any constraint on the shape of the profile of the play take-up cam outside a wide angular sector such as twice the cumulative transmission play.

Thanks to the characteristics of the invention which have just been mentioned, the gears of the part common to the first and to the second gear train always keep their functional contacts when the angular distance between the current position and the predefined position of the control cam. trip is less than or equal to the cumulative transmission clearance. And this even if a user has just set the alarm time by turning the indicator hand clockwise. It will therefore be understood that the invention has the advantage of guaranteeing that the time at which the alarm clock rings in fact corresponds to the programmed wake-up time which is displayed by the indicator hand.

According to a particular embodiment of the invention, the profile of the play take-up cam comprises an eminence with a convex vertex oriented so that, when the trigger cam is in the predefined angular position, the point contact between the roulette or inclined, on the one hand, and the profile, on the other hand, is located at the level of the convex top of the eminence. In addition, a radius which connects the axis of rotation of the play take-up cam to the highest point of the vertex makes an angle of between 25 ° and 70 ° (advantageously an angle of between 35 ° and 60 °, preferably an angle approximately 45 °) with the direction of the force exerted by the caster or the incline on the play take-up cam. It will be understood that it is not necessary to specify the sign of the above-mentioned angle. Indeed, according to the invention, the torque generated by the force exerted by the wheel or the incline on the play take-up cam must be oriented in the opposite direction to the given direction. This additional condition implicitly determines the sign of the angle.

BRIEF DESCRIPTION OF THE FIGURES

• la figure 1 est une illustration schématique en plan de dessus montrant la roue et la came de déclenchement, ainsi que la came de rattrapage de jeu, le ressort et l'incliné d'un mécanisme de réveil conforme à un premier mode de réalisation particulier de l'invention;
• la figure 2 est une vue coupe transversale du premier train d'engrenages du mécanisme de réveil représenté en partie dans la figure 1 ;
• la figure 3 est une illustration schématique en plan de dessus montrant la roue et la came de déclenchement, ainsi que la came de rattrapage de jeu, le ressort et l'incliné déjà illustrés dans la figure 1, la figure 3 montrant la configuration de ces éléments 8h30 avant l'heure de réveil programmée;
• la figure 4 est semblable aux figures 1 et 3, mais illustre la configuration 1 heure avant l'heure de réveil programmée;
• la figure 5 est semblable aux figures 1, 3 et 4, mais illustre la configuration 40 minutes avant l'heure de réveil programmée;
• la figure 6 est semblable aux figures 1 et 3 à 5, mais illustre la configuration au moment du déclenchement de la sonnerie;
• la figure 7 est semblable aux figures 1 et 3 à 6, mais illustre la configuration 3h20 après l'heure de réveil programmée;
• la figure 8 est semblable aux figures 1 et 3 à 7, mais illustre la configuration 7h10 après l'heure de réveil programmée;
• la figure 9 est semblable aux figures 1 et 3 à 8, mais illustre la roue et la came de déclenchement, ainsi que la came de rattrapage de jeu, le ressort et l'incliné alors que ces éléments sont transitoirement dans une configuration qui serait normalement la leurs 4 heures après l'heure de réveil programmée, cette dernière étant en train d'être réglée vers l'avant ;
• la figure 10 est semblable aux figures 1 et 3 à 9, mais illustre la configuration dans laquelle se trouvent normalement la roue et la came de déclenchement, ainsi que la came de rattrapage de jeu, le ressort et l'incliné 3h20 après l'heure de réveil programmée, cette dernière étant toujours en train d'être réglée vers l'avant ;
• la figure 11 est semblable aux figures 1 et 3 à 10, mais illustre la configuration 5 minutes avant l'heure de réveil programmée;
• la figure 12 est semblable aux figures 1 et 3 à 11, mais illustre la configuration au moment du déclenchement de la sonnerie à l'heure de réveil programmée ;
• la figure 13 est une vue en plan de dessus montrant la roue et la came de déclenchement, ainsi que la came de rattrapage de jeu, le ressort et l'incliné d'un mécanisme de réveil conforme à un deuxième mode de réalisation particulier de l'invention ;
• la figure 14 est une illustration schématique en plan de dessus semblable à la figure 13 et montrant partiellement un mécanisme de réveil conforme à une variante alternative du deuxième mode de réalisation de l'invention.

Other characteristics and advantages of the present invention will become apparent on reading the description which follows, given solely by way of non-limiting example, and made with reference to the appended drawings in which:

• the figure 1 is a schematic illustration in top plan showing the wheel and the release cam, as well as the play take-up cam, the spring and the incline of a wake-up mechanism according to a first particular embodiment of the invention ;
• the figure 2 is a cross-sectional view of the first gear train of the wake-up mechanism shown in part in figure 1 ;
• the figure 3 is a schematic illustration in top plan showing the wheel and the release cam, as well as the play take-up cam, the spring and the incline already illustrated in the figure. figure 1 , the figure 3 showing the configuration of these elements 8:30 a.m. before the scheduled wake-up time;
• the figure 4 is similar to figures 1 and 3 , but shows the configuration 1 hour before the programmed wake-up time;
• the figure 5 is similar to figures 1 , 3 and 4 , but shows the configuration 40 minutes before the programmed wake-up time;
• the figure 6 is similar to figures 1 and 3 to 5 , but illustrates the configuration when the bell is triggered;
• the figure 7 is similar to figures 1 and 3 to 6 , but shows the configuration 3:20 after the programmed wake-up time;
• the figure 8 is similar to figures 1 and 3 to 7 , but shows the configuration 7:10 am after the programmed wake-up time;
• the figure 9 is similar to figures 1 and 3 to 8 , but illustrates the wheel and the release cam, as well as the play take-up cam, the spring and the incline while these elements are transiently in a configuration which would normally be theirs 4 hours after the programmed wake-up time, the latter being adjusted forward;
• the figure 10 is similar to figures 1 and 3 to 9 , but illustrates the configuration in which the wheel and the release cam are normally found, as well as the play take-up cam, the spring and the incline 3h20 after the programmed wake-up time, which is still being set forward;
• the figure 11 is similar to figures 1 and 3 to 10 , but shows the configuration 5 minutes before the programmed wake-up time;
• the figure 12 is similar to figures 1 and 3 to 11 , but illustrates the configuration when the alarm is triggered at the programmed wake-up time;
• the figure 13 is a top plan view showing the wheel and the release cam, as well as the play take-up cam, the spring and the incline of a wake-up mechanism according to a second particular embodiment of the invention;
• the figure 14 is a schematic top plan illustration similar to the figure 13 and partially showing a wake-up mechanism according to an alternative variant of the second embodiment of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS

The following indications that the wheel and the trip cam rotate in the "clockwise" or "counterclockwise direction", as the case may be, are to be understood in the context of a top view such as that of the figure 1 .

The figure 1 is a schematic illustration in top plan showing the wheel and the trigger cam (respectively referenced 24 and 11), as well as the play take-up cam 21, the spring 23 and the incline 27 of a wake-up mechanism according to a particular embodiment of the invention. We can see in the figure 1 that the spring is formed by a curved elastic blade 23 which is fixed by one of its ends, and that the other end of the elastic blade comprises an end portion in the form of a pallet which, in the example illustrated, constitutes the inclined 27. As shown in the figures, the assembly formed by the spring 23 and the incline 27 is therefore made in one piece. We However, it will be understood that in accordance with other embodiments of the invention, the incline could be formed by the edge of the head of a hammer, the latter being biased against the play take-up cam by a spring, one end of which would come to rest against the hammer. Moreover, according to still other embodiments, the head of the hammer could be constituted by a roller biased against the profile of the play take-up cam.

Referring again to the figure 1 , it can also be seen that the trigger cam 11 has a circular profile interrupted by a single notch 15, and that it is fixedly mounted on the trigger wheel 24 in a coaxial position. In accordance with the embodiment which is the subject of the present example, the trigger wheel 24 is itself connected to the hour wheel of the movement (not shown in FIG. figure 1 ) by a first gear train (not shown in the figure 1 ) so as to be rotated in a given direction (corresponding to the counterclockwise direction in the drawings) at the rate of one revolution in 24 hours (or according to a variant, at the rate of one revolution in 12 hours). Notch 15 rotates at the same speed as the trigger wheel and is arranged to trigger the strike mechanism when it reaches a predefined angular position (shown in Figure figure 1 symbolically by an index referenced 17). The triggering system of the wake-up mechanism of the present example can be of known type. For example of the same type as described in the patent document CH 703 615 B1 . Those skilled in the art will understand in particular that the triggering system also comprises a triggering lever (not shown) provided with a beak which is permanently biased against the profile of the cam 11 by a return spring (not shown). It will further understand that, in a manner known per se, at the programmed wake-up time, the beak of the lever suddenly drops into the notch 15, which makes tilt the trigger lever around its axis so as to control the triggering of the bell.

Referring again to the figure 1 , it can be understood that, in the situation shown, the time remaining before the trigger corresponds to the time required for the notch 15 to travel, in the counterclockwise direction, the distance separating the current position from the notch (the position that the notch occupies in the figure) of the predefined angular position (this angular distance is represented in the figure 1 by an arrow referenced 19). It may also be recalled that the notch 15 is driven at the rate of one revolution in 24 hours and that it therefore pivots by 15 ° per hour. The wake-up mechanism of the invention is arranged to allow a user to modify the wake-up time indicated by the display by actuating an external control member (not shown). According to the invention, when the user programs the wake-up time, he not only changes the programmed time indicated by the display, but he also modifies the difference existing between the current angular position and the predefined angular position. of the trigger cam. In addition, the adjustment of the difference between the current angular position and the predefined angular position is not done by changing the predefined angular position, but on the contrary is done by rotating the trigger wheel so as to change the current angular position. .

The figure 2 is a partial cross-sectional view of the wake-up mechanism of the figure 1 . The figure 2 illustrates more particularly the first gear train which connects the hour wheel 25 of the movement to the trigger wheel 24 of the alarm mechanism. The 25 hour wheel is rotated in the center of the movement and it is driven by the movement at the speed of one revolution in 12 hours. It can be seen that it is in engagement with a return 48 itself in engagement with the planet carrier 49 of a differential gear 50. The differential gear 50 also comprises an input mobile 51 formed of a pinion gear. input 51a and an input wheel 51b and an output mobile 52 formed of an output pinion 52a and an output wheel 52b. The entry 51 and exit 52 mobiles are mounted coaxially on either side of the planet carrier 49. We can still see in the figure 2 that the wheel 49 carries a satellite 53 comprising an upper satellite wheel 53a in mesh with the input pinion 51a and a lower satellite wheel 53b in mesh with the output pinion 52a. Finally, the output wheel 52b of the differential gear meshes with the trigger wheel 24 of the alarm mechanism.

Always referring to the figure 2 , we can see an alarm hand 54 which is driven on the input mobile 51 and cooperates with a graduation present on the dial (not shown) of the timepiece to indicate the alarm time set by the 'user. In normal operation of the movement of the timepiece, the torque transmitted to the input mobile 51 through the differential gear is not high enough to counter the friction due to the overturning of the input mobile, and the mobile 51 remains therefore blocked. Consequently, the differential gear train 50 transmits the movement of the hour wheel by the output mobile 52 only. It will be further specified that the gear ratios of the first gear train are such that, for two revolutions of the hour wheel 25, the wheel 24 and the release cam complete one revolution.

According to the invention, the alarm mechanism also comprises a system for setting the programmed wake-up time (not shown) comprising a control member which can be actuated manually (not shown) and arranged to control the alarm hand 54 ( figure 2 ). The alarm time setting system is designed so as to allow a user to act on the input mobile 51 with sufficient torque to overcome the resistance due to backlighting. The user can therefore turn the input mobile of the differential gear 50, while also rotating the alarm hand 54. It will be understood that the part of the differential gear 50 which connects the input mobile 51 to the wheel The trigger is a second gear train, the ratios of which are such that when the alarm hand 54 makes one revolution, the trigger wheel 24 also completes one revolution.

According to the invention, the alarm mechanism comprises a first gear train which connects the hour wheel 25 to the trigger cam 11 ( figure 1 ) and a second gear train which connects display 54 to the trigger cam. In addition, the first and the second gear train comprise a common part which, in the present example, is formed by a first gear between the teeth of the wheel 52b of the output mobile of the differential gear 50 and that of the wheel. trigger 24, a second gear between the teeth of the upper planet wheel 53a and that of the pinion 51a of the input mobile, and finally, a third gear between the teeth of the lower planet wheel 53b and that of the pinion 52a of the output mobile. Each of these gears is inevitably associated with a certain angular deflection, and this deflection contributes to an accumulated transmission play from the common part to the first and to the second gear train. In this example, the cumulative transmission clearance is 8 °. An angle of 8 ° corresponds to an offset of 32 minutes between, on the one hand, the programmed wake-up time indicated by hand 54, and on the other hand, the time at which the trigger cam 11 actually reaches the predefined angular position 17 ( figure 1 ).

Referring again to the figure 1 , it can be seen that, in the example illustrated, the play take-up cam 21 has the shape of a cylindrical washer associated with an eminence 29 in the form of a finger which projects radially from the circumference of the washer. Now if we turn to the figure 5 , for example, it can be understood that the force exerted by the paddle (in other words, the inclined) 27 on the eminence (in other words, the finger) 29 is not oriented in the direction of the axis of rotation of the play take-up cam 21. The force exerted on the cam therefore generates a torque capable of causing it to pivot. It will further be understood that, in the position shown in figure 5 , the torque generated tends to rotate the play take-up cam 21 and the release cam 11 clockwise.

According to the invention, when the modulus of the angle which separates the current angular position of the trigger cam 11 from the predefined position is less than or equal to the cumulative transmission clearance, the torque generated is oriented in the opposite direction to the given direction. and it is strong enough to tension the gears of the common part to the first and second gear train. As indicated above, in the embodiment which is the subject of this example, the cumulative transmission clearance is 8 °. Thus, it can be verified that, in the present example, when the modulus of the angle which separates the current angular position of the triggering cam from the predefined position is less than or equal to 8 °, the spring 23 and the vane 27 are kept away from the axis of rotation of the play take-up cam 21 due to the shape of the profile of the latter. Indeed, the radii of the profile of the play take-up cam 21 which pass through the point of contact of the profile with the pallet 27 are large enough to keep the spring 23 armed. In addition, the slope of the profile of the take-up cam play 21 at the point of contact is such that the torque generated is oriented in the opposite direction to the direction given and that it is strong enough to tension the gears of the common part to the first and to the second gear train.

Example:

According to the invention, the alarm mechanism comprises a display arranged to indicate a programmed wake-up time. This display is not shown in the figures 1 and 3 to 12 annexed. By way of example, it will be admitted that with regard to figures 3 to 7 , the programmed wake-up time is 6.30 a.m. The figure 3 illustrates the trigger cam 11 in the angular position that it occupies 8:30 a.m. before reaching the predefined angular position at the programmed wake-up time. In other words, the figure 3 illustrates the situation at 10 p.m. It can be verified that the angle separating the angular position in which the trigger cam is represented from the predetermined angular position 17 is equal to 127.5 °. It can also be noted that the pallet 27 is not resting against the play take-up cam 21, these two elements being separated one by one. the other by a small space. Indeed, the figure 3 illustrates a situation in which the spring 23 is fully disarmed. As already mentioned, the degree of winding of the spring is a function of the position of the pallet 27, and it will also be understood that the distance separating the pallet from the axis of rotation of the play take-up cam 21 reaches a minimum when the spring is completely released. Under these conditions, if, as in the example shown, the play take-up cam 21 comprises a sector in which the radius of its profile is less than this minimum distance, the pallet 27 cannot come to bear against the profile of the play take-up cam 21 inside this sector.

According to an advantageous embodiment of the invention, the pallet 27 is arranged to come into contact with the profile of the play take-up cam 21 only at points for which the radius of the play take-up cam is greater than or equal. at a determined minimum length, and the profile of the play take-up cam comprises at least one sector within which the radius of the profile is always less than this determined minimum length. An advantage of this embodiment is that the amount of energy dissipated by the friction between the vane 27 and the profile of the play take-up cam 21 is reduced. According to an advantageous variant of the above embodiment, the profile of the play take-up cam comprises a single sector in which the radius of the play-take-up cam is always greater than or equal to the determined minimum length, whereas 'outside the single sector, the radius of the play take-up cam is always less than the determined minimum length.

The figure 4 illustrates the trigger cam 11 in the angular position it occupies at 5.30 am. In other words, 1 hour before reaching the predefined angular position at the programmed wake-up time. We can notice that in the figure 4 , as in figure 3 , a small space separates the pallet 27 from the play take-up cam 21, so that the pallet does not exert any force on the play take-up cam.

The figure 5 illustrates the trigger cam 11 in the angular position it occupies at 5:50 am. In other words, 40 minutes before reaching the predefined angular position at the programmed wake-up time. It can be seen that at 5:50 am, the paddle 27 is resting against the top of the finger 29 of the play take-up cam 21. It can be understood that at that time, the play take-up cam has just started to move. arm the spring 23 by pushing back the pallet, so that mechanical energy begins to be transferred from the movement of the timepiece to the spring.

The figure 6 illustrates the triggering cam 11 in the angular position it occupies when the alarm is triggered at 6.30 am, the cam therefore being in the predefined position 17. It can be seen that the paddle 27 is still resting against the finger 29 , and that a ray which joins the top of the finger from the axis of rotation of the play take-up cam 21 makes an angle at an angle of approximately 45 ° with the direction of the force exerted by the vane 27 on the play take-up cam. The play take-up cam 21 continues to charge the spring 23, and the force exerted, in return, the pallet 27 on the play take-up cam generates a torque which opposes counterclockwise rotation of the trigger cam (the given direction). It will be understood that this torque contributes to keeping the gears of the part common to the first and to the second gear train taut ( figure 2 ).

The figure 7 illustrates the trigger cam 11 in the angular position that it occupies 3.20 hours after the programmed wake-up time. In other words, at 9:50 a.m. It can be verified that the angle separating the angular position in which the triggering cam is represented from the predefined angular position 17 is equal to 50 °. It can also be seen that a radius which joins the top of the finger 29 from the axis of rotation of the backlash cam 21 is substantially parallel to the direction of the force exerted by the vane 27 on the backlash cam. take-up play. It will be understood that, in this configuration, the pallet 27 is in equilibrium on the top finger 29 and that the force which it exerts on the take-up cam of game does not generate significant torque, either in one direction or the other. In addition, the distance separating the pallet 27 from the axis of the play take-up cam 21 is at its maximum.

The figure 8 illustrates the trigger cam 11 in the angular position that it occupies 7:10 am after the programmed wake-up time. In other words, at 1:40 p.m. It will be noted that at this time, the spring 23 is again completely disarmed. In the present example, we imagine that at that moment, the user of the timepiece actuates the control member of the alarm time setting system and causes the latter to advance with the aim of schedule at 1:45 p.m. The user actuates the control unit in the direction which causes the change of the wake-up time forwards. We have seen above that when a user thus advances the wake-up time to a later time, the rate of the gear train which constitutes the common part between the first and the second gear train changes direction. This change begins by causing the reversal of the contacts between the teeth, before the trigger cam 11 starts to rotate in the opposite direction to the direction given as shown in figure 9 (in the figures, the opposite direction to the direction given corresponds to the clockwise direction).

The figure 9 represents the situation being adjusted, when the programmed wake-up time display is advancing and transiently indicates 9.40 a.m. It can be seen that by advancing the programmed wake-up time from 6.30 am, the user has caused the winding of the spring 23. However, in the configuration shown in figure 9 , the torque generated by the pallet 27 on the play take-up cam 21 is still oriented in the given direction. It will therefore be understood that this torque does not make it possible to return the contacts between the toothings to their initial functional configuration. On the contrary, the torque generated by the pallet 27 on the play take-up cam 21 is oriented so as to accentuate, if possible, the difference between the displayed alarm time and the time at which the trigger cam should actually reach the end. predefined angular position. However, the gap will be caught up in the next step.

The figure 10 represents the situation being adjusted, when the display of the programmed wake-up time is in the process of advancing and has just passed 10:10 a.m. It can be seen that the torque exerted on the play take-up cam 21 by the pallet 27 has now changed direction, this torque now being oriented in the direction opposite to the direction given, so that it accompanies the rotation of the cam. trigger 11 clockwise. It will be understood that this torque now tends to bring the contacts between the teeth of the part common to the first and to the second gear train back to their starting functional configuration. The games will now catch up as soon as the intensity of the torque is sufficient.

The figure 11 represents the situation after the user has finished setting the wake-up time to 1:45 p.m. It is still 1:40 p.m. The difference between the current angular position and the predefined angular position of the trigger cam is only 1.25 °. Thanks to the presence of the torque generated by the pallet 27, the gear clearances have been taken up, and there is no longer any difference between the displayed alarm time and the time at which the trigger cam should actually reach the predefined angular position. Indeed, the alarm went off at 1:45 p.m. ( figure 12 ).

The figures 13 and 14 are top plan views showing respectively the wheel and the trigger cam, as well as the play take-up cam, the spring and the incline of two variants of a wake-up mechanism according to a second particular embodiment of the invention. A large part of the components of the wake-up mechanism according to this second exemplary embodiment are identical to the components of the wake-up mechanism of the first example. This is the reason why these elements are designated in the figures by the same reference numbers. Referring first to the figure 13 , we can see that, in this second example, the trigger cam 11 has a circular profile interrupted by two notches 15a and 15b which are arranged in diametrically opposed positions. In addition, the play take-up cam 21 has the shape of a cylindrical washer associated with two eminences 29a and 29b in the form of fingers which protrude radially from the circumference of the washer. It can further be seen that the two fingers 29a and 29b are also arranged in diametrically opposed positions. It will also be noted that the other elements illustrated in the figure 13 are identical to the corresponding elements of the figures 3 to 12 .

The trigger wheel 24 is the wake-up mechanism of the figure 13 is designed to be rotated at the rate of one revolution in 24 hours. However, as the triggering cam 11 has two notches 15a and 15b arranged in diametrically opposed positions, the cam 11 causes the striking mechanism to trigger every 12 hours. With reference to the figure 13 , it can be seen that the profile of the play take-up cam 21 is oriented with respect to the release cam 11 so that, when the release cam 11 is in the position in which the notch 15a causes the release of the striking mechanism, the point of contact between the pallet 27 and the play take-up cam 21 is at the level of the convex top of the finger 29b, and that when the trigger cam 11 is in the position in which the notch 15b triggers the striking mechanism, the point of contact between the pallet 27 and the play take-up cam 21 is located at the level of the convex top of the finger 29a. It will be noted that the force exerted by the paddle 27 on the top of the finger with which it is in contact is the same whether it is the notch 15a or the notch 15b which caused the triggering of the striking mechanism.

Referring now to the figure 14 , we can see that, the represented alarm mechanism is practically identical to that of the figure 13 , the only difference is that the trigger cam 11 shown in the figure 14 has only a single notch 15a. We can understand that the orientation of the play take-up cam 21 relative to the release cam 11 is chosen so that, when the release cam 11 is in the predefined angular position, on the one hand the point of contact between the pallet 27 and the play take-up cam 21 is at the convex top of the pin 29b, and on the other hand, the force exerted by the vane 27 on the top 29b produces a torque oriented in the opposite direction of the given direction. It can also be noted that finger 29a is not in contact with the pallet 27 when the modulus of the angle which separates the current angular position of the triggering cam from the predefined position is less than the cumulative transmission clearance, in other words at 8 °. The finger 29a therefore does not contribute to taking up play. It will be understood from this example that the invention does not impose any constraint on the shape of the profile of the play taking up cam outside the angular sector of the profile which is in contact with it. the pallet when the modulus of the angle which separates the current angular position of the triggering cam from the predefined position is less than the cumulative transmission clearance.

It will also be understood that various modifications and / or improvements obvious to a person skilled in the art can be made to the embodiment which is the subject of the present description without departing from the scope of the present invention defined by the appended claims.

Claims (10)

1. A wake-up mechanism for a mechanical timepiece comprising:

   - a striking mechanism;

   - a motor-spring arranged to unwind while driving the striking mechanism following triggering of the latter;

   - a trigger system comprising a trigger cam (11) arranged to be connected to the hour wheel (25) of the movement by a first gear train so as to be driven in rotation, in a given direction, around an axis at a rate of one revolution in twelve or twenty-four hours, and arranged to command triggering of the striking mechanism when it reaches a predefined angular position;

   - a display (54) arranged to indicate a programmed wake-up time at which the trigger cam (11) should command triggering of the striking mechanism, after having traveled the angular distance separating a current angular position from the predefined angular position (17);

   - a setting system for setting the programmed wake-up time comprising a control member that can be actuated manually and arranged to control the display (54), the setting system also comprising a second gear train arranged to connect the display to the trigger cam (11), so that the wake-up time setting system allows the current angular position of the trigger cam to be modified, while shifting the programmed wake-up time indicated by the display, the second gear train being arranged so that the hour wheel (25) does not change the display (54) when it drives the trigger cam (11);

   - the first and the second gear train comprising a common part directly upstream of the trigger cam (11), and the gears of the common part having a cumulative transmission play capable of giving the trigger cam an angular play sufficient to give rise to a substantial offset between the programmed wake-up time and the time at which the trigger cam reaches the predefined angular position (17);

   - characterized in that the mechanism comprises a play take-up cam (21) fixed coaxially to the trigger cam (11), and a roller or an inclined surface (27) biased against the profile of the play take-up cam by the return force of a spring (23), the play-take-up cam, on the one hand, and the roller or inclined surface, on the other hand, being arranged to cooperate so that the force exerted by the roller or the inclined surface on the play take-up cam generates a torque capable of causing the latter to pivot, and

   - in that the profile of the play take-up cam (21) is such that, when the modulus of the angle which separates the current angular position of the release cam (11) from the predefined position is less than or equal to the cumulative transmission play, the generated torque is oriented in the opposite direction to the given direction and it is strong enough to tension the gears in the common part that is part of both the first and the second gear train.
2. The wake-up mechanism according to claim 1, characterized in that the profile of the play take-up cam (21) comprises an eminence (29) having a convex top oriented so that when the trigger cam (11) is in the predefined angular position, on the one hand the point of contact between the roller or the inclined surface (27) and the play take-up cam (21) is at the convex top of the eminence, and on the other hand a radius which joins the highest point of the top from the axis of rotation of the play take-up cam makes an angle between 25 ° and 70 ° with the direction of the force exerted by the roller or the inclined surface on the play take-up cam.
3. The wake-up mechanism according to claim 2, characterized in that the radius which joins the highest point of the top from the axis of rotation of the play take-up cam makes an angle of between 35 ° and 60 ° with the direction of the force exerted by the roller or the inclined surface on the play take-up cam.
4. The wake-up mechanism according to claim 3, characterized in that the radius which joins the highest point of the top from the axis of rotation of the play take-up cam makes an angle of approximately 45 ° with the direction of the. force exerted by the roller or the inclined surface on the play take-up cam.
5. The wake-up mechanism according to any one of claims 2, 3 and 4, characterized in that the play take-up cam (21) has the shape of a cylindrical washer associated with a finger (29) projecting radially from the circumference of the washer.
6. The wake-up mechanism according to any one of the preceding claims, characterized in that the roller or the inclined surface (27) is arranged to come into contact with the profile of the play take-up cam (21) only at points of the profile for which the length of the radius of the play take-up cam (21) passing through said point is greater than or equal to a determined minimum length, and in that the profile of the play take-up cam comprises at least one sector inside which the length of the radii of the play take-up cam is less than the determined minimum length.
7. The wake-up mechanism according to claim 6, characterized in that the profile of the play take-up cam (21) comprises a single sector (29) in which the radius of the play take-up cam is always greater than or equal to the determined minimum length, while outside the single sector (29), the radius of the play take-up cam is always less than the determined minimum length.
8. A wake-up mechanism for a mechanical timepiece comprising:

   - a striking mechanism;

   - a motor-spring arranged to unwind while driving the striking mechanism following triggering of the latter;

   - a trigger system comprising a trigger cam (11) arranged to be connected to the hour wheel (25) of the movement by a first gear train so as to be driven in rotation, in a given direction, around an axis at the rate of one revolution in twenty-four hours, and arranged to command triggering of the striking mechanism when it reaches a first or a second predefined angular position, the first and the second predefined angular positions being separated by 180 ° ;

   - a display (54) arranged to indicate, over 12 hours, a programmed wake-up time at which the trigger cam (11) should command triggering of the striking mechanism, after having traveled the angular distance separating a current angular position from the first or second predefined angular position (17);

   - a setting system for setting the programmed wake-up time comprising a control member that can be actuated manually and arranged to control the display (54), the setting system also comprising a second gear train arranged to connect the display to the trigger cam (11), so that the wake-up time setting system allows the current angular position of the trigger cam to be modified, while shifting the programmed wake-up time indicated by the display, the second gear train being arranged so that the hour wheel (25) does not change the display (54) when it drives the trigger cam (11);

   - the first and the second gear train comprising a common part directly upstream of the trigger cam (11), and the gears of the common part having a cumulative transmission play capable of giving the trigger cam an angular play sufficient to give rise to a substantial offset between the programmed wake-up time and the time at which the trigger cam reaches the predefined angular position (17);

   - characterized in that the mechanism comprises a play take-up cam (21) fixed coaxially to the trigger cam (11), and a roller or an inclined surface (27) biased against the profile of the play take-up cam by the return force of a spring (23), the play take-up cam, on the one hand, and the roller or inclined surface, on the other hand, being arranged to cooperate so that the force exerted by the roller or the inclined surface on the play take-up cam generates a torque capable of causing the latter to pivot, and

   - in that the profile of the play take-up cam (21) is such that, when the modulus of the angle between the current angular position of the trigger cam (11), on the one hand, and one or the other of the first and the second predefined angular positions, on the other hand, is less than or equal to the cumulative transmission play, the generated torque is oriented in the opposite direction of the given direction and it is strong enough to tension the gears from the common part that is part of both the first and the second gear train.
9. The wake-up mechanism according to claim 8, characterized in that the profile of the play take-up cam (21) comprises two eminences (29a, 29b) each having a convex top oriented so that when the trigger cam (11) is in one or the other of the first and the second predefined angular positions, on the one hand the point of contact between the roller or the incline surface (27) and the play take-up cam (21) is located at the convex top of one of the two eminences, and on the other hand a radius which joins the highest point of said top from the axis of rotation of the play take-up cam makes an angle between 25 ° and 70 ° with the direction of the force exerted by the roller or inclined surface (27) on the play take-up cam.
10. The wake-up mechanism according to claim 9, characterized in that the play take-up cam (21) has the shape of a cylindrical washer associated with two fingers (29a, 29b) projecting radially from the circumference of the washer in diametrically opposed positions.

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