EP0568499B1 - Device for displaying the power-reserve of a watch - Google Patents

Description

The present invention relates to a power reserve indicator device for a watch according to the preamble of claim 1.

The preferred field of application of such a device is that of mechanical watches, with manual or automatic winding. Its interest is obvious, since it allows the wearer of a watch of the aforementioned kind to know at any time the state of winding or disarming of the barrel spring, this state, directly translated into remaining running time until next winding, preferably in hours (possibly subdivided), being indicated by an indicating member, for example a hand whose end is located opposite a graduation or a disc moving behind a window arranged in the watch face .

The implementation of the power reserve indicator device essentially encounters two difficulties. The first comes from the fact that the element driving the indicator member must be actuated, on the one hand, by a mobile ensuring the running of the watch, for taking into account the disarming of the barrel spring and, on the other hand , by an element of the spring winding device, in connection with the winding stem if it is a manual watch, or with the oscillating weight if it is an automatic watch. The actuating element of the organ indicator is therefore subject to two contradictory commands (disarming and armament commands), which must be designed so as not to cause disorders, that is to say be synchronized resp. granted or adapted between them. The needle drive element, respectively the needle itself, will make a maximum of one revolution for the duration of the walk, which is generally between 35 and 50 hours, depending on the calibers.

In the known devices, this first problem is solved by the use of differential gears making it possible to control the indicator member (output element) by two input elements, the barrel (disarming) and the barrel shaft (armoring ). Thus, CH-263.707 discloses a spherical differential device between the ratchet and the barrel.

These devices require a large number of wheels and pinions, and this is precisely what constitutes the second problem. Indeed, if a device of this kind was built in modular form, the significant extra thickness of the resulting movement is such that the general aesthetics of the watch suffers, to the point that the attractiveness and the advantage that it provides. '' power reserve indication are greatly reduced or even destroyed. On the other hand, if the device is to be integrated into the watch, it is necessary to modify the blank, which in general is not possible. It is therefore advisable to reconcile the modular nature of the device with that of a minimum excess thickness.

There are a few devices that do not use differential gears, such as FR-548785, FR-638149, FR-872410. However, these devices all have, as information sockets, the barrel and the ratchet fixed on the barrel shaft. These two sockets are coaxial and require, to access them, interventions inside the movement of the watch. If access can be relatively easy in pocket watches or recorders on which these devices are installed, this will quickly become difficult, if not impossible, in wristwatches. In addition, the problem of thickness, in these prior art, is neither posed nor resolved.

On the other hand, these devices are not applicable to automatic watches, in which the barrel shaft continues to rotate after the complete winding of the spring by sliding the sliding spring flange. In some cases, there is a phase shift in the display (hand on the dial). Finally, in the event of an accidental shift of the display hand, for example under the effect of shocks, the occurrence of which is much more likely on wristwatches than on pocket watches, there is no automatic readjustment of the display. The necessary reliability of the reading is therefore not ensured, which practically negates the advantage of the indicating device. However, these shifts are potentially always possible, because the wheel on the axis of the display needle is positioned only by the action of a spring (jumper 8 in FR-638149).

The object of the present invention is to overcome the drawbacks which the known devices present. It is achieved by virtue of the features defined in claim 1 and the dependent claims.

The fact of providing, as means of taking information, two axes of the watch movement that are not coaxial, that is to say two axes each located on a different support (or line-support), and to realize the device in modular form, makes it possible to limit to a minimum the extra thickness - consequent to the addition of the device according to the invention - of the movement assembly more device, while ensuring very easy access, and to avoid any significant modification of the basic movement. Furthermore, the device can be installed on wristwatch movements with automatic winding, since it does not allow a permanent offset of the display hand.

fig. 1

est une vue en plan du dispositif selon l'invention et les

fig. 2 et 3

représentent ce même dispositif, respectivement en état d'armage et de désarmage.

We will describe by way of example an embodiment of the power reserve indication device according to the invention for a mechanical watch, with automatic winding, in support of the appended drawing in which the

fig. 1

is a plan view of the device according to the invention and the

fig. 2 and 3

represent this same device, respectively in arming and disarming state.

The device comprises a star wheel 1 (hereinafter star or wheel 1) carrying on its axis 1 'an indicator hand (not shown in the figure) of the power reserve, which star is engaged intermittently, of on the one hand, with a rocker 4 controlled by the winding device and, on the other hand, with a cam 10 controlled by a mobile of the movement of the watch, as will be seen through the description of the operation of said device. The wheel 1 further comprises a circular opening or groove 16 extending over an arc of a circle and a notch 1c, the functions of which we will return to later.

A barrel shaft 2, of axis 2A involved in the reassembly of the barrel spring carries a cam 3 having at least one ramp -two, 31.32, diametrically opposite, according to the example described. The rocker 4, having a spout 4 '', is subjected to the action of this cam 3 and to that of a spring 5, so as to be able to oscillate around its axis 4 'between two extreme positions shown in the figure ( one of the positions being only partially in dotted lines). Starting from one of the two positions extremes, for example that shown in dotted lines (spout 4 '' in the ramp 31), the cam 3, during a half-turn of rotation in the direction of the arrow 2 'will push the rocker 4, against the action of the spring 5, towards the extreme release position shown in solid lines. During the initiation of the next U-turn, the rocker 4 is suddenly folded down under the action of the spring 5, the spout 4 "coming again to occupy the position shown in dotted lines in the hollow of the corresponding ramp 32. In its folding movement, the rocker 4 drives a tooth of the star 1, the latter being therefore subjected to a rotation action in the direction of the arrow 6. Thus, the winding, resulting from the rotation of the barrel shaft will it be indicated by the needle, integral with star 1, via elements 3, 4, 5. The positioning of star 1 is ensured by a jumper 7.

A pinion 8 secured to an axis 8A of the train of the watch drives a wheel 9. The wheel 9 carries on its axis 9A a cam 10 mounted free in rotation and capable of being driven by a pin 11 secured to this wheel. The cam 10 has a spout 101 which can instantly pass from a position 10 '(shown in solid lines) to a position 10''(shown in dotted lines) under the action of a spring 13. In its rotational movement in the direction of the arrow 102 (the pin 11 being at a given instant (figures), against the notch 103 of a clearance (not referenced) made in the zone opposite to that of the spout 101), the cam 10 gradually lifts the spring 13. Arrival in the position 10 'shown in solid lines in the figures, the spring force will be exerted on the curved face 12 of the spout 101 and suddenly push the cam into position 10 '' (shown in dotted lines). During this phase, that is to say the sudden passage from the position 10 'to 10'', where the rotation is not ensured by the pin 11, but by the spring 13, the spout 101 of the cam 10, drives a tooth of the star 1, the latter being subjected to a rotational action in the direction of the arrow 14. At the same time, the notch 104 will arrive near the pin 11, without however touching it . The wheel 9 continuing to rotate, the cam will again be driven in rotation when the pin 11 comes into contact with the notch 103. Thus, disarming, resulting from the rotation of the pinion 8, will it be indicated by the needle attached to star 1, the positioning of which will also be ensured by the jumper 7.

It will be understood that in the embodiment described and shown in the figures, the gear 8.9 is calculated so that the wheel 9 makes one revolution for a half-revolution of the cam 3. In general, the number of turns of the wheel 9 is proportional to the number of turns of the cam 3, the proportionality factor being equal to the number of ramps that the cam 3 has.

In the case of an automatic winding watch, when the barrel spring is fully armed, the oscillating mass continues to drive the barrel spring via a sliding strap. In this situation of fully winding the spring, the indicator needle should no longer be trained. To this end, a pin 15 fixed on the movement is engaged in the circular opening 16 of the wheel 1. When the spring is fully armed, as shown in FIG. 2, the end 16 'of this opening comes into contact with the pin 15, so that the action of the rocker 4 is blocked, and the rotation of the wheel 1 carrying the indicator member is hampered. Furthermore, if, accidentally, for example during an impact, the wheel 1, and consequently the indicator member, shifts in the direction of the arrow 6, and the end 16 'abuts against the element fixed 15, registration is automatically ensured on the first full cocking.

Figure 3 shows the complete disarming situation. In this position, the end 16 '' of the circular groove 16 abuts against the fixed element 15. Again, in a similar manner to what has just been observed with regard to reinforcement in the hypothesis of an unwanted offset of the indicating member, if the latter is shifted not in the direction 6, but in the direction of the arrow 14, the opening 16, resp. the end 16 '' can come into contact with the pin 15 before complete disarming. The pointer of the indicator is stopped, but the watch, by finishing disarming, will cause the serge 1b of the wheel 1 to flex: the tooth 1a will retract or be erased with each passage of the cam 10, this retraction being made possible by the notch 1c, and the registration will thus be ensured. It is observed in support of the figures that the notch 1c is oriented radially, extends from the outside of the teeth to the groove 16 and is made near the end 16 'of the groove 16, the tooth the being the first adjacent to the notch 1c and situated on the side opposite the end 16 ′ with respect to this notch.

The elastic members 7, 5, 13, will each have to create on the star 1 different couples between them and adapted to each other. As an indication, it is advantageous that, if the actuating torque exerted on the wheel 1 by the spring or jumper 7 has a reference value equal to one, the actuating torque exerted on the wheel 1 by the lever 4 controlled by the spring 5 must have a value equal to approximately two, and the actuating torque exerted on the wheel by the spout 10 'controlled by the spring 13, must have a value equal to approximately six, the spout 10' having to counter the cumulative actions of springs 5 and 7.

The device according to the invention is of simple construction, has a reduced number of parts and does not significantly increase the thickness of the watch. It comes in modular form allowing it to be installed outside the movement. Thus, in the first place, the increase will only be of the order of half of that which would result from a device with differential gears. Then, there is no need to provide for any particular change in size; only the heights of the pivots on which the cam 3 and the wheel 8 are mounted must be slightly increased. Finally, the various elements of the device are easily accessible. In addition, thanks to the means used, it is particularly suitable for mechanical watches with automatic winding, a resetting being carried out automatically in both directions, even following an accidental shift, which ensures perfect reliability of the reading of the indicator organ.

Claims (5)

1. Device for displaying the power reserve of a mechanical watch, in particular of a self-winding watch, comprising a star wheel (1) bearing an indicator element, said star wheel being subject to a rotational action during rewinding by means of a first group of elements, comprising a swing (4) under the action of a cam (3) having at least one ramp and coacting with the barrel stem (2), on one hand, and of a first resilient element (5), on the other hand, for allowing the drive of one tooth of the star wheel (1) at each winding movement, and subject to a rotational action during unwinding by means of a second group of elements, comprising a cam (10) having a nose (101) for allowing the drive of one tooth of the star wheel at each unwinding movement, these actions being intermittent and inverse, the positioning of the wheel (1) being ascertained by a second resilient element (7), characterised by the fact that the cam (10) having the nose (101) coacts with a driving wheel (8) on a shaft (8A) of the watch, that the shaft (2A) of the barrel stem (2) and the staff (8A) of said driving wheel (8) do not have the same support, said displaying device thus having as information uptake points two non coaxial axes of the watch movement, and by the fact that the device is in modular form and arranged at the exterior of the movement.
2. Device according to claim 1, characterised in that the star wheel (1) comprises a circular opening (16), and that the indicator element is immobilised when the barrel spring is fully rewound, thanks to the action of a fixed element (15) engaged in the opening (16), one (16') of the extremities of said opening coming abutting against the fixed element (15) and blocking the rotation of the wheel (1), the barrel stem (2) being able to make a continued rotation under the action of an oscillating weight.
3. Device according to claim 1 or 2, characterised in that the driving wheel (8) engages with a wheel (9) having a shaft (9A), the cam (10) having the nose being mounted for free rotation on the shaft (9A) of said wheel (9) and being driven either by a pin (11) fastened on said wheel (9) or by a third resilient element (13), the other extremity (16") of the opening (16) coming into abutment against the fixed element (15) during complete unwinding.
4. Device according to any one of claims 1 to 3, characterised by the fact that, during an accidental dislocation, an automatic reset is ascertained in both directions, either by the action of the nose (101) of the cam (10) which will hide, in bending the rim (1b) of the star wheel (1), one tooth (la) adjacent to a radial slot (1c) in said star wheel, the second extremity (16") abutting against said fixed element (15), or by the stopping of the star wheel (1) when the first extremity (16') abuts against the fixed element (15).
5. Device according to claim 3 or 4, characterised in that the driving torques applied to the star wheel (1) by said resilient elements (7, 5, 13) are adapted to each other, the torques applied by the first resilient element (5) and the third resilient element (13) being preferably about twice and, respectively, six times higher than the torque applied by the second resilient element (7).

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