Actuating mechanism for a flexible indicator needle

Description

Technical field of the invention

[0001] The present invention relates to an actuating mechanism for a flexible display needle. Technological background

[0002] The present invention relates to flexible display hands. Such hands, already known in the prior art, comprise a first drive barrel connected to a first end of a first flexible arm, and a second drive barrel connected to a first end of a second flexible arm. At their second end, the first and second flexible arms are connected to each other by a tip. In a free, unconstrained state of the flexible display hand, the first and second drive barrels are spaced apart from each other. Conversely, a service position in which the flexible display hand has a defined shape and length is a constrained position in which the first drive barrel and the second drive barrel are arranged coaxially around the same axis of rotation.In this constrained position, the first drive barrel is mounted with a first defined pre-stress angle, and the second drive barrel is mounted with a second defined pre-stress angle opposite to that of the first drive barrel. The flexible display hand is arranged to change its shape and length in a desired manner when the angular position of the second drive barrel varies relative to the angular position of the first drive barrel by pivoting about the rotation axis. For this purpose, the first flexible arm of the flexible display hand performs an angular rotation θ1 which is applied by a clockwork movement to the flexible display hand to display the information.For the second flexible arm, the angular rotation θ1 applied by the clockwork movement to the flexible display hand being modulated by a rotation angle φ by an actuating mechanism, this rotation angle φ, applied to the second flexible arm of the flexible display hand, determines the rotation and the change of shape and length of the flexible display hand.

[0003] Mechanisms for actuating a flexible display hand with variable length are already known in the state of the art. These different actuating mechanisms are all based on the same operating principle: an angular rotation θ1, applied to an input of the actuating mechanism by the watch movement, is modulated by a rotation angle φ by this actuating mechanism, this rotation angle φ, applied with an opposite direction to the first and second flexible arms of the flexible display hand, determining the rotation and the change in shape and length of the flexible display hand.

[0004] Document EP 2 863 274 A1 discloses an elastic watch hand, comprising a first drive barrel secured to a flexible blade.

[0005] This elastic needle is in one piece and said flexible blade comprises at least a first flexible segment between said first barrel and a first apex, said first apex being at a variable distance from said first barrel depending on forces applied to said flexible blade.

[0006] This document also discloses a timepiece display mechanism comprising such an elastic hand: it comprises first means for driving said first barrel of said elastic hand around a pivot axis, and second means for stressing said elastic hand to vary the position of at least one said vertex of said elastic hand relative to said pivot axis.

[0007] With these prior art drive mechanisms, the flexible display hands describe trajectories of various shapes (circular, oval, triangular, etc.) in a single revolution; in other words, from a determined starting point, the flexible display hands make a complete revolution, deforming in the desired way, then return to their starting point and the process starts again from the beginning. Summary of the invention

[0008] The present invention aims to provide an actuating mechanism for a flexible display needle making it possible to vary the trajectories described by such a flexible display needle when it is driven by such an actuating mechanism.

[0009] To this end, the present invention relates to an actuating mechanism for a flexible display needle comprising a first drive barrel connected to a first end of a first flexible arm, and a second drive barrel connected to a first end of a second flexible arm, the first and second flexible arms being connected to each other by a tip at their second end, the first barrel being mounted with a first defined pre-stress angle, and the second barrel being mounted with a second defined pre-stress angle in the opposite direction to that of the first barrel, so that the elastically pre-stressed flexible display needle constantly keeps the entire actuating mechanism under tension during normal operating conditions of the actuating mechanism, the actuating mechanism comprising a first cannon pinion onto which the first drive barrel of the flexible display needle is driven,this first cannon pinion being driven by a clockwork movement, this first cannon pinion driving an intermediate wheel which in turn drives a second cannon pinion onto which the second drive pipe is driven, the flexible display hand moving between an initial position and a final position in which it makes a jump to return to its initial position, the flexible display hand changing shape and length in a desired manner during this movement, which induces an additional elastic tension induced by the change in angular position of the second drive pipe relative to the first drive pipe which is added to the elastic tension induced by the mounting of the first and second drive pipes on the respective first and second cannon pins,the kinematic connection between the intermediate wheel and the second cannon pinion being momentarily interrupted at the moment when the flexible display hand makes its jump, the second cannon pinion then being temporarily free to rotate on itself, disconnected from the rest of the actuating mechanism, so that the additional elastic tension is released, which causes the second cannon pinion to pivot, the first and second cannon pins then being in direct engagement via the pin which precisely positions the second cannon pinion relative to the first cannon pinion 14 so that the first cannon pinion drives not only the second cannon pinion, but also the intermediate wheel until a moment when the second cannon pinion is again engaged with the intermediate wheel. The position of the pin makes it possible to ensure that the resumption of the drive is done correctly by avoiding a tip-on-tip blockage.,

[0010] According to particular embodiments of the invention: the intermediate wheel comprises a first and a second intermediate wheel, the second intermediate wheel being rotatably coupled with the first intermediate wheel, the first cannon pinion driving the first intermediate wheel, while the second intermediate wheel drives the second cannon pinion; the second cannon pinion is provided with a pin which projects into a slot cut out in the board of the first cannon pinion, the second intermediate wheel having, at one point on its perimeter, a sector without a tooth; the slot, in the shape of an arc of a circle centered on the center of the first cannon pinion, is delimited at its two ends by a first and a second base; the slot extends over an angular sector determined by the change in shape and length desired for the flexible display hand to which an additional angular sector must be added to take into account the size of the pin;the angle α Aig formed by the bisector of the first and second flexible arms which extends between an axis of rotation of the first and second drive barrel and the tip of the flexible display needle, with the direction of the bisector in the initial position of the flexible display needle is given by: ; α Aig = θ 1 ⋅ 1 + i 2 with θ1 the angular rotation applied by the clockwork to the first flexible arm of the flexible display hand from its initial position; i the gear ratio between the first and second flexible arms of the flexible display hand.

[0011] Thanks to these characteristics, the present invention provides an actuating mechanism arranged so as to drive a flexible display hand for example over two complete revolutions, the second revolution having a different geometry from the first. From a determined initial starting point, the flexible display hand makes a first revolution, then a second revolution following the first before returning to its initial starting point and repeating the trajectory again. The actuating mechanism according to the invention is also distinguished by its simplicity and its low height.

[0012] According to particular embodiments of the invention, the actuating mechanism comprises a friction clutch intended to be arranged between a time-setting mechanism capable of being controlled by a crown, and the first cannon-pinion, the time-setting mechanism and the crown being comprised by the watch movement, the friction clutch being configured so that, when the crown occupies a time-setting position and is urged so as to move the flexible display hand in the clockwise direction, it transmits a torque to the first cannon-pinion in order to drive said flexible display hand in the clockwise direction.

[0013] According to particular embodiments of the invention, the friction clutch is configured so that, when the crown is urged, when it is in the time-setting position, to move the flexible display hand counterclockwise, it slips when it is subjected to a torque greater than a predefined threshold.

[0014] According to particular modes of implementation, the first and second carriageways are in direct engagement via the pin which precisely positions the second carriageway relative to the first carriageway so that the first carriageway drives not only the second carriageway, but also the intermediate mobile until a moment when the second carriageway is again engaged with the intermediate mobile, the position of the pin making it possible to ensure that the drive is resumed correctly while avoiding tip-to-tip blocking. Brief description of the figures

[0015] Other characteristics and advantages of the present invention will emerge more clearly from the following detailed description of an embodiment of the actuating device according to the invention, this example being given purely for illustrative and non-limiting purposes only in conjunction with the appended drawing in which: there Figure 1 is a plan view of a flexible display needle intended to be driven by an actuating mechanism according to the invention; Figure 2 is a perspective and exploded view of the actuating mechanism according to the invention; Figure 3 is a partial plan view of the actuating mechanism according to the invention in standard operating mode in which a phase shift is created between the first and second flexible arms of the flexible display needle; Figure 4is a partial plan view which illustrates the situation of the actuating mechanism according to the invention just at the moment which precedes the jump of the flexible display hand and where the phase shift between the first and second flexible arms of this flexible display hand is maximum, the second cannon pinion still being engaged with the second intermediate wheel by a last tooth of this second intermediate wheel which precedes the sector without a tooth; Figure 5 is a partial plan view which illustrates the situation of the actuating mechanism according to the invention just after the flexible display hand has made its jump and the phase shift between the first and second flexible arms is zero, the second cannon pinion still not being engaged with the second intermediate wheel, but being in direct engagement with the first cannon pinion via a pin; Figure 6 is a larger scale detail view of the Figure 5 ; there Figure 7is a larger scale detail view of the Figure 3 ; THE figures 8, 9 and 10 illustrate different types of trajectories that can be envisaged for the flexible display needle driven by the actuating mechanism according to the invention; Figure 11 represents a functional diagram of the actuating mechanism according to the invention, in which a crown is biased to move the flexible display hand clockwise; the Figure 12 is analogous to the Figure 11 except that the crown is used to move the flexible display hand counterclockwise. Detailed description of the invention

[0016] The present invention proceeds from the general inventive idea which consists of providing, in a watch movement, an actuating mechanism for a flexible display hand making it possible to vary the trajectories described by such a flexible display hand. More precisely, the actuating mechanism according to the invention is designed to drive a flexible display hand so that this flexible display hand, starting from an initial starting point, successively performs a first, then a second revolution whose geometry differs from the first revolution, before returning to its initial starting point from the end of its second revolution and repeating the same trajectory again. One of the advantages of the present invention lies in the fact of being able to display different ranges of values ​​of the quantity displayed on each of the first and second revolutions. The actuating mechanism according to the invention also proves to be very simple and takes up little space in height.

[0017] The embodiment of the actuating mechanism according to the invention which will be described below by way of non-limiting example only can allow the display of a 24-hour time indication. A typical example concerns the display of the current time for which the midnight-noon time slot can thus be displayed on the first rotation, and the noon-midnight time slot on the second rotation.

[0018] Designated as a whole by the general reference numeral 1, a flexible display needle capable of being driven by an actuating mechanism according to the invention is illustrated in Figure 1. This flexible display needle 1 comprises a first drive barrel 2 connected to a first end of a first flexible arm 4, and a second drive barrel 6 connected to a first end of a second flexible arm 8. At their second end, the first and second flexible arms 4 and 8 are connected to each other by a tip 10. In a free, unconstrained state of the flexible display needle 1 shown in Figure 1 , the first and second training guns 2, 6 are spaced apart from each other.

[0019] Conversely, a service position in which the flexible display needle 1 has a defined shape and length is a constrained position in which the first drive barrel 2 and the second drive barrel 6 are arranged coaxially around an axis of rotation D (see Figure 2). In this constrained position, the first drive barrel 2 is mounted with a first defined pre-stress angle, and the second drive barrel 6 is mounted with a second defined pre-stress angle opposite that of the first drive barrel 2. As will be better understood from the following, the flexible display needle 1 is arranged to change shape and length in a desired manner when the angular position of the second drive barrel 6 varies relative to the angular position of the first drive barrel 2 by pivoting about the axis of rotation D .

[0020] Designated as a whole by the general reference numeral 12, an embodiment of an actuating mechanism of the flexible display needle 1 according to the invention is illustrated in Figure 2. This actuating mechanism 12 comprises a first cannon pinion 14 on an axis 15 from which the first drive barrel 2 of the flexible display hand 1 is driven. This first cannon pinion 14 is driven by a clockwork movement (not shown), for example in the clockwise direction. The driving of the first cannon pinion 14 by the clockwork movement can be done directly or with the interposition of a gear train.

[0021] The first cannon pinion 14 therefore plays a driving role in the operation of the actuating mechanism 12. More precisely, this first cannon pinion 14 drives a first intermediate wheel 16 of an intermediate wheel 18 in a counterclockwise direction. This intermediate wheel 18 also comprises a second intermediate wheel 20 coupled in rotation with the first intermediate wheel 16 and which therefore also rotates in a counterclockwise direction. Finally, the actuating mechanism 12 comprises a second cannon pinion 22 driven in rotation in the clockwise direction by the second intermediate wheel 20. This second cannon pinion 22, mounted freely in rotation on the axis 15 of the first cannon pinion 14, comprises an axis 24 on which the second drive barrel 6 is driven. It will be understood that the meshing between the first and second cannon pins 14, 22 on the one hand, and the intermediate wheel 18 on the other hand, can be done directly or by means of additional pinions and wheels.

[0022] The actuating mechanism 12 is also characterized in that the second cannon pinion 22 is provided with a pin 26 which projects into a slot 28 cut out in the board of the first cannon pinion 14. This slot 28, in the shape of an arc of a circle centered on the center of the first cannon pinion 14, is delimited at its two ends by a first and a second bottom 30 and 32 respectively and extends over an angular sector of 162.5° in the non-limiting example illustrated in the drawing. This value of the angular sector is determined by the desired change in shape and length for the flexible display hand 1 to which an additional angular sector must be added to take into account the size of the pin 26, for example 20°, as well as a safety margin, typically 2.5°. We also see in the drawing that the second intermediate wheel 20 has, at one point on its perimeter, a sector 34 without teeth.The role of these different elements will be detailed below.

[0023] By way of illustrative example only, assume now that the first cannon pinion 14 is driven by the clockwork in a clockwise direction at a rate of one revolution per day. In turn, the first cannon pinion 14, meshing with the first intermediate wheel 16, drives the latter to rotate counterclockwise, which causes the second intermediate wheel 20 to rotate counterclockwise as well. Finally, the second intermediate wheel 20 drives the second cannon pinion 22 in a clockwise direction.

[0024] Due to the gear ratios between the first and second cannon pins 14, 22 and the first and second intermediate wheels 16, 20 that have been chosen here to illustrate the actuating mechanism 12 according to the invention, the second cannon pin 22 makes less than one revolution per day (0.799). This has the effect that the first and second flexible arms 4, 8 of the flexible display hand 1 move apart from each other, while the pin 26 begins to move into the lumen 28. The angular distance φ that separates the pin 26 from the first bottom 30 represents the phase shift applied to the first and second flexible arms 4, 8 of the flexible display hand 1 by the actuating mechanism 12 operated by the clockwork (see Figure 3). Care should be taken to note that in normal operating mode of the actuating mechanism 12, that is to say when the toothless sector 34 of the second intermediate wheel 20 is not opposite the second cannon pinion 22, in other words when the second intermediate wheel 20 and the second cannon pinion 22 are engaged, the elastically prestressed flexible display hand 1 constantly keeps the entire actuating mechanism 12 under tension, whereby the second cannon pinion 22 is held in position. Indeed, the constrained mounting of the flexible display hand 1 induces in it an elastic tension which tends to bring its flexible arms 4, 8 closer to each other.To this elastic tension induced by the mounting under stress of the flexible display needle 1 is added an additional elastic tension induced by the change in shape and length of the flexible display needle 1 under the effect of the variation of the angular position of the second drive barrel 6 relative to the angular position of the first drive barrel 2 by pivoting around the axis of rotation D.

[0025] When, at the end of the second revolution of the flexible display needle 1, the toothless sector 34 of the second intermediate wheel 20 arrives opposite the second cannon pinion 22 as illustrated in Figure 4 , this second roadway 22 will find itself temporarily free to turn on itself, disconnected from the rest of the actuating mechanism 12. Indeed, as visible in the Figure 4which illustrates the situation of the actuating mechanism 12 just before the jump of the flexible display hand 1, the second cannon pinion 22 which tends to want to turn clockwise to catch up with the phase shift φ which separates it from the first cannon pinion 14 is still engaged with the second intermediate wheel 20 by a last tooth A . Thereafter, the second intermediate wheel 20 continues to rotate counterclockwise until the last tooth Aby which the second cannon pinion 22 was still engaged with the second intermediate wheel 20 disappears and that the sector 34 without teeth of this second intermediate wheel 20 finds itself opposite the second cannon pinion 22. This has the immediate consequence that the additional elastic tension induced by the change in angular position of the second drive barrel 6 relative to the first drive barrel 2 is released, which causes the second flexible arm 8 to relax and the second cannon pinion 22 to pivot clockwise. The second cannon pinion 22 thus catches up with the phase shift φ which separated it from the first cannon pinion 14 and which had reached 140° at the end of the second revolution of the flexible display hand 1. Indeed, the light extends over 162.5°, but the second cannon pinion 22 only turns 140°.During this catch-up, the pin 26 comes into contact with the bottom 30 of the light 28 and the phase shift φ between the first and second cannons 14, 22 is cancelled (see . Figure 5). After this jump, the toothless sector 34 of the second intermediate wheel 20 is still opposite the second cannon pinion 22, which is therefore still free. However, the elastic tension to which the flexible display hand 1 is subjected maintains the pin 26 at the bottom 30 of the slot 28, so that the first and second cannon pins 14, 22 are coupled in rotation. Still driven by the clockwork movement, the first cannon pinion 14 rotates and in turn drives the second cannon pinion 22. Since these first and second cannon pins 14, 22 are in direct engagement and there is no gear ratio between them, these two cannon pins 14, 22 rotate at the same speed. Consequently, during this phase of operation of the actuating mechanism 12, the trajectory of the flexible display hand 1 is circular.

[0026] Of course, when turning, the first carriageway 14 drives not only the second carriageway 22, but also the first and second intermediate wheels 16, 20. A moment therefore arrives where the second carriageway 22 finds itself in engagement with the second intermediate wheel 20. A change in the drive of the second carriageway 22 therefore occurs at that moment: from a direct engagement with the first carriageway 14, the second carriageway 22 finds itself again driven in a standard manner by the second intermediate wheel 20.

[0027] Adjusting the position of the pin 26 is crucial because it is this which ensures that, when the drive resumes, the second cannon pinion 22 meshes with the second intermediate wheel 20 without tip-to-tip locking.

[0028] It is important to note that it is to the first cannon-pinion 14 with which the first flexible arm 4 of the flexible display hand 1 is associated that the driving torque provided by the clockwork movement is applied. Therefore, considering the bisector of the first and second flexible arms 4, 8 which extends between the axis of rotation D of the first and second drive pipes 2 and 6, when they are in the service position, and the tip 10 of the flexible display hand 1, the angle α Aig formed by this bisector with the direction of the bisector in the initial position of the flexible display hand 1 which, in the purely illustrative and non-limiting example shown in the drawing, corresponds to the 6 o'clock-12 o'clock axis, does not coincide exactly with the angular rotation θ1 applied by the clockwork movement to the first flexible arm 4 of the flexible display hand 1.In other words, the mathematical relationship between the angle α Aig and the angle θ1 is given by: . α Aig = θ 1 ⋅ 1 + i 2 with α Aig the angle formed by the bisector of the first and second flexible arms which extends between the axis of rotation D and the tip of the flexible display hand, with the direction of the bisector in the initial position of the flexible display hand; θ1 the angular rotation applied by the clockwork to the first flexible arm of the flexible display hand from its initial position; i the gear ratio between the first and second flexible arms of the flexible display hand (0.799 in this case).

[0029] It goes without saying that the present invention is not limited to the embodiment which has just been described and that various simple modifications and variants can be envisaged by those skilled in the art without departing from the scope of the invention as defined by the appended claims.

[0030] In the example described above, from its starting point until the moment it makes its jump to return to its initial position, the tip 10 of the flexible display hand 1 describes a spiral trajectory over two revolutions (see figure 8 ). In other words, while the first and second cannon pins 14, 22 make two complete revolutions between two consecutive jumps of the flexible display hand 1, the second intermediate wheel 20 makes one complete revolution given that the return of the flexible display hand 1 to its initial position occurs when the toothless sector 34 of the second intermediate wheel 20 is opposite the second cannon pinion 22.

[0031] Of course, as shown in the Figure 9 , by adapting the pitch between the turns and the number of turns, other trajectories of the tip 10 of the flexible display needle 1 can be envisaged. Similarly, see Figure 10, the actuating mechanism 12 according to the invention can be arranged so that the flexible display hand 1 makes several jumps at each revolution.

[0032] Due to the elastic tension of the hand, any attempt to move the flexible display hand 1, when setting the time, so that it makes a jump to move from the initial position to the final position, i.e. to make the jump in the counterclockwise direction if we consider the figures 2 And 8 , would lead to a blockage of the actuating mechanism 12 or to deterioration of the latter.

[0033] To protect against such a situation, the actuating mechanism 12 comprises a friction clutch 41 intended to be arranged between the first cannon pinion 14 and a time-setting mechanism 42 comprising a time-setting train controlled by a winding crown 43. These characteristics are shown schematically in the Figures 11 and 12 .

[0034] The time-setting mechanism 42 and the crown 43 are included in the watch movement in which the actuating mechanism 12 according to the invention is intended to be arranged and are known as such to those skilled in the art.

[0035] In a known manner, the crown 43 is capable of controlling the time-setting mechanism 42, that is to say of acting on the latter, when it occupies a time-setting position.

[0036] Following the activation of the crown 43 while it is in the time-setting position, in order to move the flexible display hand 1 in the clockwise direction, the friction clutch 41 is configured so as to transmit, to the first cannon-pinion 14, all or part of a torque to which it is subjected by the time-setting mechanism 42, in order to drive the flexible display hand 1 in the clockwise direction. This scenario is shown in the Figure 11, in which the transmission of movement is symbolized by the thick line arrows.

[0037] When the crown 43 is urged, when it is in the time-setting position, so as to move the flexible display hand 1 counterclockwise, the friction clutch 41 is configured to slip when it is subjected to a torque greater than a predefined threshold, so as to avoid the transmission, to the first cannon pinion 14, of too high a torque. The torque reaches this predefined threshold when the flexible display hand 1 occupies its initial position and the crown 43 is urged so as to drive the hand to make the jump to its final position.

[0038] Thus, the friction clutch 41 makes it possible to transmit a torque from the crown 43 to the first cannon pinion 14 so as to move the flexible display hand 1, in the counterclockwise direction, from its final position to its initial position, but interrupts this torque transmission when it occupies its initial position. This arrangement therefore makes it possible to avoid any blocking or breakage of the actuating mechanism 12 which would occur if the flexible display hand 1 attempted to jump from its initial position to its final position. This scenario is shown in the Figure 12 , in which the thin line arrows represent the non-transmission of movement.

[0039] The friction clutch 41 may be formed by any clutch known to those skilled in the art, such as a shim, an arm clutch, a friction drive wheel, etc., and is arranged in the time-setting gear train. In particular, the friction clutch 41 is located between a sliding pinion and the first cannon pinion 14 and is therefore not actuated during manual winding of the movement which passes through a winding pinion to a ratchet known as such to those skilled in the art.

[0040] In a manner well known to those skilled in the art, the timepiece movement also comprises a time-setting clutch, not shown in the figures, designed to be arranged between the first cannon pinion 14 and a going train. Such a time-setting clutch makes it possible, during time-setting, to decouple, beyond a certain torque threshold, the first cannon pinion 14 and the going train so as not to damage the going train or an escapement kinematically linked to the going train. Nomenclature

[0041] 1. Flexible display needle 2. First training barrel 4. First flexible arm 6. Second training barrel 8. Second flexible arm 10. Tip DRotation axis 12. Actuation mechanism 14. First track 15. Axis 16. First intermediate wheel 18. Intermediate movable part 20. Second intermediate wheel 22. Second track 24. Axis 26. Pin 28. Hole 30. First bottom 32. Second bottom 34. Sector 41. Friction clutch 42. Timing mechanism 43. Crown

Claims

1. Mechanism (12) for actuating a flexible display hand (1) comprising a first drive pipe (2) connected to a first end of a first flexible arm (4), and a second drive pipe (6) connected to a first end of a second flexible arm (8), the first and second flexible arms (4, 8) being connected to one another by a tip (10) at their second end, the first pipe (2) being mounted at a defined first prestressing angle, and the second pipe (6) being mounted at a defined second prestressing angle in the opposite direction to that of the first pipe (2), so that the elastically prestressed flexible display hand (1) constantly maintains the entire actuating mechanism (12) under tension during normal operation of the actuating mechanism (12), the actuating mechanism (12) comprising a first cannon-pinion (14) onto which the first drive pipe (2) of the flexible display hand (1) is driven, this first cannon-pinion (14) being driven by a horological movement, this first cannon-pinion driving an intermediate wheel set (18) which in turn drives a second cannon-pinion (22) onto which the second drive pipe (6) is driven, the flexible display hand (1) moving between an initial position and a final position in which it makes a jump to return to its initial position, the flexible display hand (1) changing shape and length in a desired way during this movement, which induces additional elastic tension induced by the change in angular position of the second drive pipe (6) relative to the first drive pipe (2) which is added to the elastic tension induced by the mounting of the first and second drive pipes (2, 6) on the respective first and second cannon-pinions (14, 22), the kinematic link between the intermediate wheel set (18) and the second cannon-pinion (22) being momentarily interrupted at the time when the flexible display hand (1) makes its jump, the second cannon-pinion (22) then being temporarily free to rotate about itself and disconnected from the rest of the actuating mechanism (12), so that the additional elastic tension is released, causing the second flexible arm (8) to relax and the second cannon-pinion (22) to pivot, the first and second cannon-pinions (14, 22) then being directly engaged via a pin (26) in a slot (28), the first cannon-pinion (14) driving not only the second cannon-pinion (22), but also the intermediate wheel set (18), until such time as the second cannon-pinion (22) is again engaged with the intermediate wheel set (18).

2. Actuating mechanism according to claim 1, characterised in that the intermediate wheel set (18) comprises a first and a second intermediate wheel (16, 20), the second intermediate wheel (20) being rotationally coupled with the first intermediate wheel (16), the first cannon-pinion (14) driving the first intermediate wheel (16), whereas the second intermediate wheel (20) drives the second cannon-pinion (22).

3. Actuating mechanism according to claim 2, characterised in that the second cannon-pinion (22) is provided with the pin (26) which projects into the slot (28) cut in the plate of the first cannon-pinion (14), the second intermediate wheel (20) having, at a place on its perimeter, a toothless sector (34).

4. Actuating mechanism according to claim 3, characterised in that the slot (28), which is in the shape of an arc of a circle centred on the centre of the first cannon-pinion (14), is delimited at its two ends by a first and a second back (30, 32).

5. Actuating mechanism according to claim 4, characterised in that the slot (28) extends over an angular sector determined by the desired change in shape and length of the flexible display hand (1), to which an additional angular sector must be added to take account of the overall dimensions of the pin (26).

6. Actuating mechanism according to one of claims 3 to 5, characterised in that the angle αAig formed by the bisector of the first and second flexible arms (4, 8) that extends between an axis of rotation of the first and second drive pipe (2, 6) and the tip (10) of the flexible display hand (1), with the direction of the bisector when the flexible display hand (1) is in its initial position, is given by: α Aig = θ 1 ⋅ 1 + i 2 where - θ1 is the angular rotation applied by the horological movement to the first flexible arm (4) of the flexible display hand (1) from its initial position; - i is the gear ratio between the first and second flexible arms (4, 8) of the flexible display hand (1).

7. Actuating mechanism according to claim 1, characterised in that it comprises a friction clutch (41) intended to be arranged between a hand-setting mechanism (42) capable of being controlled by a winding button (43), and the first cannon-pinion (14), the hand-setting mechanism (42) and the winding button (43) being comprised in the horological movement, the friction clutch (41) being configured such that, when the winding button (43) is in a hand-setting position and is operated in order to move the flexible display hand (1) in the clockwise direction, it transmits a torque to the first cannon-pinion (14) in order to drive said flexible display hand (1) in the clockwise direction.

8. Actuating mechanism according to claim 7, characterised in that the friction clutch (41) is configured such that, when the winding button (43) is operated, when it is in the hand-setting position, in order to move the flexible display hand (1) in the counter-clockwise direction, it slides when it is subjected to a torque above a predefined threshold.

9. Actuating mechanism according to claim 1, characterised in that the first and second cannon-pinions (14, 22) are then directly engaged via the pin (26), which precisely positions the second cannon-pinion (22) relative to the first cannon-pinion (14), so that the first cannon-pinion (14) drives not only the second cannon-pinion (22), but also the intermediate wheel set (18), until such time as the second cannon-pinion (22) is again engaged with the intermediate wheel set (18), the position of the pin (26) ensuring that the drive is resumed correctly, preventing the tips from mutually blocking one another.