EP0654718B1 - Driving mechanism for the hands of a timepiece - Google Patents

Description

The present invention relates to a mechanism for driving the hands of a timepiece comprising, arranged between a plate and a bridge, a first rotor-motor driving a board of a first intermediate mobile, said first intermediate mobile carrying a pinion driving a first center mobile, the latter comprising a board meshing on said pinion and a barrel on which is fitted a needle displaying a first time unit, and a second rotor-motor driving a board from a second mobile intermediate, said second intermediate mobile bearing a pinion driving a second center mobile, coaxial on the first, this second center mobile comprising a board meshing on said pinion and a through shaft the barrel, tree on which a needle is fitted displaying a second unit of time.

Document EP-B-0 393 605 already describes a part of watchmaking each of whose hands is driven by a rotor-motor. In this document, each rotor pinion is engaged with a toothed wheel, these wheels being mounted coaxially to each other and on either side of a platinum. Each of the wheels directly controls a hand indicating a unit of time. This construction is relatively simple because it does not use a intermediate mobile placed between the rotor-motor and the center mobile. However, it has the disadvantage to generate noise caused by the shock of the two teeth of the motor pinion on the teeth of the wheel center. In addition, the whole mechanism being mounted on the reinforced stator of the motors, it was necessary to provide a tube to support the center mobiles.

To avoid these disadvantages, the mechanism of the present invention, in addition to meeting the definition generic of the first paragraph above, is characterized in that the first and second intermediate mobiles are identical and interchangeable and that they are arranged upside down between the plate and the bridge. Other original features will appear on the reading of the following text.

• la figure 1 est une vue en plan du mécanisme de l'invention, vue sur laquelle les mobiles en cause n'ont été que symbolisés et où la platine et le pont ont été omis,
• la figure 2 est une coupe selon la ligne II-II de la figure 1, coupe dans laquelle la platine, le pont et tous les mobiles ont été représentés dans leur intégralité, et dans laquelle les aiguilles sont disposées du côté de la platine, et
• la figure 3 est une coupe semblable à celle de la figure 2 dans laquelle les aiguilles ont été disposées du côté du pont.

The invention will now be understood on reading the following description given by way of example, of two possible forms of implementation. This description refers to the attached drawing in which:

• FIG. 1 is a plan view of the mechanism of the invention, a view in which the mobiles in question have only been symbolized and in which the plate and the bridge have been omitted,
• FIG. 2 is a section along line II-II of FIG. 1, section in which the plate, the bridge and all the mobiles have been shown in their entirety, and in which the needles are arranged on the side of the plate, and
• Figure 3 is a section similar to that of Figure 2 in which the needles were arranged on the side of the bridge.

Figure 1 is a plan view of the the invention. In this figure has been represented a motor 34 fitted with two rotor motors 5 and 6 and a stator unique 12. The engine is completed by a core 35 and a single coil 25. This motor is nothing but a advanced execution of that described in patent CH-B-675 940 in which the rotors are able to drive two needles independently of each other and whose axes are coaxial. As explained in the cited document, in acting on the shape of the notches 13a, 13b and 14a, 14b for example, it is possible to selectively order rotors 6 and 5 by means of type pulses different, for example pulses of the same duration but with different hash rates. In the case present, if we apply to coil 25 a pulse full, the two hands progress one step at the same time time, whereas if it's a chopped pulse that's applied, only one minute hand advances one step.

The present invention is not limited to the engine described above and it will be understood that the use of two independent motors each driving a needle is also possible, such as the use of the arrangement described in the patent EP-B-0 393 605 cited upper.

The mechanism of the invention is shown schematically in Figure 1 which shows the motor 34, its two rotor motors 5 and 6 and a gear mechanism which will now be explained by means of section II-II shown in Figure 2. The cog is located between a plate 7 and a gear train 8 not shown on the figure 1.

As seen in Figure 1, and particularly better on figure 2, the mechanism comprises a first rotor-motor 6 equipped with a magnet 32 and a pinion 30. This first rotor-motor 6 drives by its pinion 30 a plate 15 of a first intermediate mobile 4. This first intermediate mobile 4 carries a pinion 16 which drives a first center mobile 2 by a board 17 which is provided with this first center mobile 2. The latter comprises also a barrel 18 on which is fitted a hand 11 which displays a first unit of time.

The mechanism shown in Figures 1 and 2 includes another second motor rotor 5 fitted with a magnet 33 and a pinion 31. This second motor rotor 5 drives by its pinion 31 a board 18 of a second intermediate mobile 3. This second intermediate mobile 3 carries a pinion 19 which drives a second center mobile 1. Figure 2 shows clearly that the second mobile of center 1 is coaxial with first center mobile 2. This second center mobile 1 has a board 20 engaged on the pinion 19 of the second intermediate mobile 3 and still has a shaft 21 crossing the barrel 18. On this shaft 21 is fitted a hand 10 which displays a second unit of time.

According to an essential characteristic of the invention, Figure 2 clearly shows that the first and second intermediate mobiles 4 and 3 are identical, therefore interchangeable and that they are arranged upside down between the plate 7 and the gear train 8. So is it necessary to make only one kind of mobile intermediary to train the first center mobile 2 and the second center mobile 1, which decreases the number of different parts to make. It is therefore sufficient to arrange the pinion 16 of the first intermediate mobile 4 of the side of the plate 7 and the pinion 19 of the second mobile bridge side 8 to ensure mounting correct mechanism.

The similarity of the intermediate mobiles 4 and 3 can drive that of rotors-motors 6 and 5 and that of central boards 17 and 20.

As far as rotors are concerned, it goes without saying that the cuts of gears 30 and 31 must be identical. If we also arrange for the pivots, the height of the pinions 30 and 31, the magnets 32 and 33 and the tigerons are the same for the two rotor-motors, we will have made two identical pieces and interchangeable and thus reduced the costs of manufacturing.

Regarding plates 17 and 20 making respectively part of the first and second mobiles 2 and 1, it also goes without saying that their diameters and number of teeth should be equal. It will therefore be understood that if we arrange to provide them with the same central bore 23 and 24, we will have produced two identical boards and consequently reduces the manufacturing tools to be used in action.

In conclusion of what has just been said, the mechanism of the invention is greatly simplified by the use of two identical rotor-motors, two identical intermediate mobiles and two wheels center with different axes, barrel and shaft, but whose boards are identical.

In addition to the manufacturing simplicity mentioned above, we will understand that it is to our advantage to propose a thinnest possible mechanism. To reach this goal, another characteristic of the invention provides that the plates 15 and 18 of the first and second mobiles intermediaries 4 and 3, in addition to the identical character of these last, are in a median plane 22 located at equal distances between plate 7 and the gear train 8. In this way, the mechanism has a thickness minimum because the boards 17 and 20 of the center mobiles 2 and 1 can be brought closer to the median plane 22, which leaves a maximum of space for the stator 12 of the arranged motor between plate 17 and plate 7.

The arrangement which has just been described presents a another advantage. Indeed, plates 15 and 18 of intermediate mobiles located in the median plane 22, the boards 17 and 20 of the first and second mobiles of center 2 and 1 can be arranged on either side of the median plane 22 and equidistant from it, as this is shown in Figure 2. This layout particular allows to return the two mobiles of center 2 and 1 and the two intermediate mobiles 4 and 3 to arrive at the situation illustrated in Figure 3 where the hands 10 and 11 are located on the gear train 8. This new situation, obtained without difficulty and at means of the same mobiles composing the mechanism, is that a mechanism intended to be assembled in a watch monobloc with bottom made of a part with the middle, like a plastic case for example. We understand that the situation shown in figure 2, with hands 10 and 11 emerging from the platinum side 7, is that suitable for a ordinary movement, delivered for itself and intended to be mounted by the bottom of the timepiece.

We can even consider a transformable mechanism on request from the situation presented in figure 2 to that of Figure 3 or vice versa, mechanism fitted not only of the same mobiles, but still of the same turntable 7 and of the same bridge 8. This requires that the end 26 of the shaft 21 not carrying a needle is mounted in rotation in a bearing 9 driven into the plate 7 (figure 3) or in bridge 8 (figure 2) and that barrel 18 crossing respectively bridge 8 or plate 7 either adjusted in rotation in one of said bridge or plate and that the outside diameter 27 of the bearing 9 is substantially equal to the outside diameter 28 of the barrel 18 where the latter crosses bridge 8 or plate 7.

The mechanism described above can be used in any analog timepiece including hands are controlled independently of each other by a electric circuit. More specifically, his use is well suited in a chronograph watch or an alarm watch with two hands likely to display, in response to the actuation of a control device, either time of day or time alarm indicating hour and minute, a time timed indicating the minute and second. Such a chronograph watch is described, for the control part, in patent application CH 01497 / 93-2 filed on May 17, 1993, published under the number CH 685 142 and belonging to the same holder as that of this invention.

Claims (9)

1. Mechanism for driving the hands of a timepiece comprising, arranged between a bottom plate (7) and bridge (8), a first rotor-motor (6) driving a plate (15) of a first intermediate wheel carrying a pinion (16) driving a first centre wheel (2), this latter comprising a plate (17) meshing with said pinion (16) and a pipe (18) upon which is pressed a hand (11) displaying a first unit of time, and a second rotor-motor (5) driving a plate (18) of a second intermediate wheel (3), said second intermediate wheel carrying a pinion (19) driving a second centre wheel (1), coaxial to the first, said second centre wheel comprising a plate (20) meshing with said pinion (19) and a shaft (21) passing through the pipe (18), a hand (10) displaying a second unit of time being pressed onto said shaft, characterised in that the first and second intermediate wheels (4, 3) are identical and interchangeable and in that they are arranged head to tail between the bottom plate (7) and the bridge (8).
2. Mechanism according to claim 1, characterised in that the first and second rotor-motors (6, 5) are identical and interchangeable.
3. Mechanism according to claim 1, characterised in that the plates (17, 20) of the first and second centre wheels (2, 1) are made in an identical manner insofar as concerns both the diameter and number of teeth, and the central bore (23, 24) which they exhibit.
4. Mechanism according to claim 1, characterised in that the plates (15, 18) of the first and second intermediate wheels (4, 3) are arranged in a median plane (22) situated at equal distances between the bottom plate (7) and the bridge (8).
5. Mechanism according to claim 1, characterised in that the first and second rotor-motors (6, 5) form part of a sole single stator motor (12) fitted with a single coil (25).
6. Mechanism according to claim 1, characterised in that the first and second rotor-motors (6, 5) each form part of an independent motor fitted with a stator and a coil.
7. Mechanism according to claim 4, characterised in that the plates (17, 20) of the first and second centre wheels (2, 1) are situated on either side of the median plane (22) and at equal distances from the latter, so that said wheels may be used as wished with the hands (11, 10) situated on the bottom plate (7) or on the bridge (8).
8. Mechanism according to claim 7, characterised in that the end (26) of the shaft (21) not carrying a hand is mounted so as to rotate in a through bearing (9) driven into the bottom plate (7) or into the bridge (8) and in that said pipe (8) passing through the bridge (8) or bottom plate (7) respectively is fitted so as to rotate in one of said bottom plate or bridge, the external diameter (27) of said bearing (9) being substantially equal to the external diameter (28) of said pipe where it passes through the bridge (8) or the bottom plate (7).
9. Chronograph watch fitted with a mechanism according to claim 1 or 2, comprising two hands (11, 10) capable of displaying, in response to the actuation of a control device, either the time of day indicating the hour and minute, or a measured time indicating the minute and the second.

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