EP3330807B1 - Alternative display device - Google Patents

Description

Technical area

The present invention relates to the field of watchmaking. More particularly, it relates to a horological display device comprising a first set of indexes to designate twelve successive hours of a day and a second set of indexes to designate the others, as well as a drive mechanism which performs switching between these two sets in order to bring the appropriate set into an active position.

State of the art

The document DE513661 describes an alternative 1-12h/13-24h display device comprising an index disc carrying two sets of intersecting indexes, one comprising the digits 0/24 to 11, the other comprising the digits 12 to 23. This disc is located behind a dial with twelve apertures, and is rotated by a step of 15° clockwise around 12 o'clock and by a step of 15° counterclockwise at around midnight, under the control of a drive mechanism. The latter comprises a wheel making one revolution in 12 hours which drives a Maltese cross at the rate of two steps, that is to say half a turn, with each rotation of the wheel. This Maltese cross in turn drives a lever which is integral in rotation with the index disk in order to make it pivot and in order to reveal the appropriate index clearance behind the windows.

However, the two-step rotation of the Maltese cross takes several hours, which results in the indexes not being correctly aligned for a long period around 0:00 and 12:00. Also, the drive system takes up a lot of space near the center of the movement, which is bulky and doesn't leave much room for other components.

The document CH106257 describes a display device which is free from this drawback. This device has a pair of "instantaneous date" type drive systems, one acting to drive the index disc in the clockwise direction, the other to perform its drive counterclockwise. This arrangement has several drawbacks. First, the presence of two drive systems is complex and even requires more space in the plane of the movement than in the realization of the document DE513661 . The free space for other components is thus limited. Secondly, the use of drive systems of the "instantaneous date" type is energy-intensive, since it requires a relatively high torque and the movement must load the two drive springs for a relatively long period, except when one of the springs is released to drive the disc. As the load on the going train varies, the isochronism of the timepiece is disturbed.

Other similar systems were unveiled in the documents CH 59 451 and DE 485 116 C .

The object of the present invention is thus to overcome the aforementioned drawbacks, and to propose a display device which performs the change from one set of indexes to another in a rapid manner, without being too bulky, nor consuming too much energy, nor cause too great a torque variation.

Disclosure of Invention

More specifically, the invention relates to a display device for a timepiece according to claim 1. This device comprises an index disk carrying a first set of indexes comprising indications corresponding to at least a part of twelve successive hours of a day as well as a second set of indexes comprising indications corresponding to at least part of the twelve other successive hours of the day, said sets of indexes being mutually intersected, that is to say that the indexes of one set alternate with those of the other. These indexes serve as indications of the time, and can be numbers, abstract signs, different colors, or other markings used to distinguish the two sets of hours. Typically, the successive twelve hours will be 1 a.m. to 12 p.m. and 1 p.m. to 12 p.m., but other sets of times are also possible, such as night and day (for example 6 p.m. to 5 a.m. respectively 6 a.m. to 5 p.m.), or any other division of the 24 hours of a day.

The display device further comprises a device for driving said index disc, which is arranged to cause the latter to pivot at the rate of one step forward and one step back per day in order to sequentially bring the one then the other of said index sets in an active position. This pivoting typically takes place with one step around 12:00 p.m., and with the other step around 12:00 a.m. The active position can be defined, for example, by means of a mask or a dial comprising notches or apertures, or by any marking which suffices to indicate which game is active.

According to the invention, the drive device further comprises an annular-shaped drive disc arranged to be continuously driven such that it rotates with a variable angular speed, said drive disc being arranged to reach a maximum speed when driving said index disc. This variable angular speed can, for example, comprise a sinusoidal component.

Furthermore, said control disc has a radial slot in which there is an eccentric pin carried by an intermediate wheel which is mounted on a support arranged to perform one revolution in 12 hours, said intermediate wheel meshing directly or indirectly with a fixed toothing .

By doing this, the pivoting of the index disc can be carried out quickly, without having to load a spring. Therefore, no significant load is imposed on the going train, and torque variations are minimized. This last advantage derives from the fact that the control disc is permanently driven by the basic movement instead of being driven first by the movement, then by a spring, and then being effectively decoupled from the movement until the moment when the leading wheel catches up with it, as it does in the device of the document CH106257 .

Advantageously, said intermediate wheel meshes with another intermediate wheel which in turn meshes with said fixed toothing. The manufacturer can thus easily determine the gear ratios so as to optimize the variations in angular speed of the control disk.

Advantageously, said fixed toothing is a ring gear with internal toothing, which can be placed around the mechanism in order to take up little space in the center of the latter.

Advantageously, said index disk has a radial slot in which an eccentric pin is placed, which is carried by a drive wheel arranged to be driven by said control disk. A simple drive system, which is able to drive the index disk one step in one direction and then one step in the other direction is thus proposed.

Advantageously, said drive wheel comprises a pinion with interrupted teeth, said pinion and said control disc being arranged to form a self-locking gear, which is therefore free of jumper for positioning the index disc. Such a training mobile can be swiveled rapidly through 180° with each drive, which results in a faster swiveling than, for example, a Maltese cross. However, the use of a Maltese cross is also possible, subject to this reduced training speed.

Finally, the invention relates to a timepiece comprising a display device as defined above.

Brief description of the drawings

• Fig. 1a - 1c sont des vues schématiques isométriques d'un dispositif d'affichage selon l'invention, vu du côté cadran, et selon trois phases d'opération (23h30, 00h00 et 00h30 respectivement) ;
• Fig. 2a - 2c sont des vues schématiques isométriques d'un dispositif d'affichage selon l'invention, sans masque, vu du côté cadran, et selon les trois mêmes phases d'opération ;
• Fig. 3a - 3c sont des vues schématiques isométriques d'un dispositif d'affichage selon l'invention, sans masque et sans la partie supérieure du support, vu du côté cadran, et selon les trois mêmes phases d'opération ; et
• Fig. 4a - 4c sont des vues schématiques isométriques d'un dispositif d'affichage selon l'invention, vu du côté fond, et selon les trois mêmes phases d'opération.

Other details of the invention will appear more clearly on reading the following description, made with reference to the appended drawings in which:

• Fig. 1a - 1c are schematic isometric views of a display device according to the invention, seen from the dial side, and according to three operating phases (11:30 p.m., 12:00 a.m. and 12:30 a.m. respectively);
• Fig. 2a - 2c are schematic isometric views of a display device according to the invention, without mask, seen from the dial side, and according to the same three phases of operation;
• Fig. 3a - 3c are schematic isometric views of a display device according to the invention, without mask and without the upper part of the support, seen from the dial side, and according to the same three phases of operation; and
• Fig. 4a - 4c are schematic isometric views of a display device according to the invention, seen from the bottom side, and according to the same three operating phases.

Embodiment(s) of the Invention

The figures 1 to 4 illustrate a display device 1 according to the invention at three stages of operation, in particular around 11:30 p.m. ( figure 1a , 2a , 3a and 4a ), 00:00 ( figure 1b , 2b , 3b and 4b ), and 00:30 ( figure 1c , 2c , 3c , 4c ).

The display device 1 comprises a frame 3, which can be part of the frame or the middle part of the timepiece (not shown) in which the device 1 is integrated. This chassis 3 serves as a support for the components of the device 1. Alternatively, the display device 1 can be built as a separate module, and in such a case the chassis 3 is dedicated to this module and is intended to be fixed to the frame of a timepiece.

An index disc 5, of annular shape, is pivotally mounted in the device. This index disc 5 carries a first set of indexes 5a comprising the numbers 1 to 11, as well as a second set of indexes 5b comprising the numbers 13 to 23, the indexes of each set 5a, 5b being alternated in such so that the sequence 13 - 1 - 14 - 2 - 15 - 3 - 16 - 4 - 17 - 5 - 18 - 6 - 19 - 7 - 20 - 8 - 21 - 9 - 22 - 10 - 23 - 11 is written in clockwise on the index disk 5. These indexes serve as indications of the time. It is also possible to provide digits representing 12:00 and 24:00/00:00, but these indexes have been omitted in the illustrated variant, or to use other sequences of digits (for example a sequence of hours representing at least part of the night, and another sequence representing at least part of the day). Alternatively, abstract signs, colors or the like can be used instead of numbers.

Superimposed on the disc of index 5 is a mask 7 (represented exclusively on the figures 1a-1c ), which is also annular in shape, and which comprises a plurality of notches 7a which define active positions for the numbers inscribed on the index disk 5. When a set of indexes 5a, 5b is below these notches, it is visible to the user, and the corresponding index set 5a, 5b is considered to be in the active position.

Alternatively, the mask may comprise apertures instead of notches, or the active positions may be indicated otherwise, for example by appropriate markings on a transparent element, on the glass of the watch, on the periphery of the chassis 3, or the like. . In the latter cases, the mask can be omitted.

The hours are indicated by an indicator member 9, represented in the form of an arrow carried by a support 11a, 11b which comprises a base plate 11b and an upper ring 11a, this support 11a, 11b being mounted in rotation around the center of the display device 1 and concentrically to the index disk 5. The support 11a, 11b is driven in rotation by a driving source (not shown), which can be mechanical or electrical, at the rate of one revolution in twelve hours. It should be noted that, although the base plate 11b is illustrated here as being a solid disc, it can also be annular in order to free up space in the center of the display device for other components, other organs of indication etc.

The index disc 5 is driven from this support 11, via a drive device 13, which forms a kinematic connection between these two components.

To this end, a first intermediate wheel 15 is rotatably mounted on the support 11. This wheel 15 meshes with a fixed toothing 17, integral with the frame 3 and hidden by the mask 7, as well as with a second intermediate wheel 19, also pivoted on the support 11. This second intermediate wheel 19 carries an eccentric pin 19a which takes place in a radial slot 21a of an annular control disc 21. The size and the number of teeth of the intermediate wheels 15, 17 can be chosen according to the needs of the manufacturer; it should be noted in particular that the intermediate wheel 15 can be of a smaller size than that illustrated here, in order to free the center of the device 1. Alternatively, the first intermediate wheel 15 could be replaced by at least one mobile, in order to further modify the speed of rotation of the second intermediate wheel 19.

Furthermore, in the variant illustrated, the control disc 21 includes a notch 21c in its inner periphery in order to allow the axis of the intermediate wheel 15 to pass.

The pin 19a rotates the control disk 21, and imposes a variable angular speed on it. This variable speed represents the sum of the angular speed of the support 11 and of a component resulting from the rotation of the second intermediate wheel 19 around its own axis. Indeed, when the pin 19a advances the control disc 21 relative to the support 11, the control disc pivots with an angular speed greater than that of the support 11. In the same way, when the pin 19a moves the control 21 relative to support 11, its angular speed is lower than that of support 11.

By averaging the angular speed of the control disk 21 over one revolution, this average value is equal to the angular speed of the support 11. However, on this average value is superimposed a sinusoidal variation, which is determined to present a maximum during the index disc drive 5. In order to reach the maximum speed at the right time in the operating cycle, an integer number of cycles of this sinusoidal variation are included in the cycle of one complete revolution of the control disc 21.

This driving of the index disk 5 is effected by means of a short toothing 23, which interacts with a driving wheel set 25 pivotally mounted on the frame 3. In the variant illustrated, the wheel set training is at 12 o'clock, but this is not compulsory. Indeed, the manufacturer can determine its position according to its needs, and/or according to the sequences of successive hours to be distinguished.

On the bottom side, this drive wheel set 25 comprises a pinion with interrupted teeth 25a, which performs a half-turn by passage of the short toothing 23. When the short toothing does not interact with the pinion 25a, the latter cooperates with a surface devoid of teeth 21b that includes the control disc 21, self-locking manner. As such, the tops of the teeth project beyond this surface 21b, and the bottoms of these teeth describe a radius less than that of the surface 21b.

This kind of gear avoids the use of a jumper to position the index disc 5, which has the effect of minimizing energy consumption.

On the dial side of mobile 25 there is an eccentric pin 25b carried by a disk which is integral in rotation with pinion 25a. This disc is barely visible in the figures, so no reference sign has been attributed to it.

This pin 25b takes place in a radial slot 5c that comprises the index disc 5. In the illustrated variant, this slot 5c is hidden by the part of the mask 7 which corresponds to the 12 o'clock/00 o'clock position.

When the index disk 5 is in one of its two stable positions, the pin 25b is halfway in the slot 5c (see the figure 2a and 2c ), and holds the index disk 5 in position, as shown in the figure 1a , 2a and 3a .

When mobile 25 is driven by control disc 21, mobile 25 performs a step of half a turn in the counterclockwise direction (considered on the dial side). The pin 25b, passing through one of the ends of the slot 25b, therefore drives the slot 5c so as to cause the index disk 5 to pivot towards its other stable position.

Considering this geometry, it is clear that the mobile 25 carrying the pin 25b performs a half-turn each time it is driven by the short toothing 23. The use of a Maltese cross and a finger instead of the pinion 25a and of toothing 23, although possible, is on the other hand disadvantageous. In order to perform a half-turn, a Maltese cross must be driven in two steps of 90°, while the pinion 25a can only perform one step of 180°. The driving of the index disc 5 will therefore be significantly slower for a Maltese cross than for the arrangement illustrated in the figures.

The figures 1 to 4 therefore illustrate the sequence of operations which rotates the index disc 5 by one step counterclockwise around 00:00, in order to bring the first set of indexes 5a into its active position. Around 12:00 p.m., the mobile 25 performs another half-turn counterclockwise, and the pin 25b drives the index disk 5 by one step clockwise, in order to bring the second set of indexes 5b in said active position. Furthermore, it should be noted that the switching of the index disk 5 is done independently of the direction of rotation of the support 11, which is practical in the event of setting the time.

Although the invention has been described above in connection with a specific embodiment, additional variants are also possible without departing from the scope of the invention as defined by the claims.

Claims (7)

1. Display device (1) for a timepiece, comprising:

   - an index disc (5) bearing a first index set (5a) comprising indications corresponding to at least a part of twelve successive hours of a day and a second index set (5b) comprising indications corresponding to at least a part of the twelve other successive hours of the day, said index sets (5a, 5b) being mutually interlaced,

   - a drive device (13) of said index disc (5) arranged to make it pivot at a rate of one step forward and one step backward per day in order to sequentially bring one and then the other of said index sets (5a, 5b) into an active position;

   said drive device (13) comprising a control disc (21) of annular form arranged to be driven permanently such that it pivots with a variable angular speed, said control disc (21) being arranged to reach a maximum speed during the driving of said index disc (5),

   said control disc (21) comprising a radial slit (21a) in which is situated an eccentric pin (19a) borne by an intermediate wheel (19) which is mounted on a support (11a, 11b) arranged to perform one revolution in twelve hours, said intermediate wheel (19) meshing directly or indirectly with a fixed toothing (17).
2. Display device (1) according to Claim 1, wherein said angular speed comprises a sinusoidal component.
3. Display device (1) according to one of Claims 1 and 2, wherein said intermediate wheel (19) meshes with another intermediate wheel (15) which in turn meshes with said fixed toothing (17).
4. Display device (1) according to one of Claims 1 to 3, wherein said fixed toothing (17) is a crown with internal toothing.
5. Display device (1) according to one of Claims 1 to 4, wherein said index disc (5) comprises a radial slit (5c) in which is situated an eccentric pin (25b) borne by a drive wheel (25) arranged to be driven by said control disc (21).
6. Display device (1) according to Claim 5, wherein said drive wheel (25) comprises a pinion with interrupted toothing (25a), said pinion (25a) and said control disc (21) being arranged to form a self-locking gear.
7. Timepiece comprising a display device (1) according to one of the preceding claims.

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