Trochoidal display mechanism

Abstract

The invention relates to a mechanism for displaying an information for a timepiece, comprising a mobile (10) intended to be driven in rotation by the movement of the timepiece about a display axis (17), a satellite (20) pivoted on the mobile (10) about a satellite axis (27) parallel to the display axis (17) and remote from a non-zero distance d1 thereof, a display area (80), an indicator (50) secured to the satellite (20) and the position of which relative to the display area (80) provides the information, and a crown (30) centered on the display axis (17) and kinematically connected to the satellite (20). The mechanism is particular in that the indicator (50) is located at a distance d2 from the satellite axis (27), which is greater than or equal to the distance d1.

Description

Technical field

[0001] The present invention relates to a trochoidal display mechanism, in particular for a timepiece. State of the art

[0002] In watchmaking technology, several examples of display mechanisms capable of moving a mobile device along a closed, non-circular path are known. These displays are sought when it is desired to offer a display with a new and original shape, to fit the shape of an elongated dial, or to give a display a special appearance that makes it easy to distinguish.

[0003] Document EP2993532 describes, for example, a hand that pivots around an axis of revolution. The hand is mounted on a wheel that follows an elliptical trajectory around the center of the watch, driven by a mechanism that includes a pivoting arm and a differential. The hand is constantly aligned with the center of the watch.

[0004] CH708264 proposes a different solution in which the movement is achieved by a mechanism comprising articulated levers, while CH702133 proposes a solution to a similar problem based on a planetary system with a gear train in the sun gear. Other implementations, notably DE29905074, use moving elements sliding in free-form grooves.

[0005] DE29903950 proposes a display mechanism in which the indicator is a point on one face of a toothed wheel that rolls inside a crown, so as to generate trochoidal, hypotrochoid or epitrochoidal trajectories. US5280461 discloses an indicator driven by a satellite wheel with a sliding tip; CH 692257 a watch with a sub-dial rotating around the center of the main dial; EP2544055 a watch with indicators displayed on a pivoting support, such as an oscillating weight.

[0006] Known systems that allow the generation of non-circular needle trajectories are often bulky and complex and / or do not allow the display to be carried out on the periphery of the dial, which makes reading the information difficult and imprecise. Brief summary of the invention

[0007] An object of the present invention is to provide a hypo- or epi-trochoidal display free from the limitations of known devices.

[0008] According to the invention, this aim is achieved by the subject of the main claim, and in particular by means of a mechanism for displaying information for a timepiece comprising a mobile intended to be rotated by the movement of the timepiece around a display axis, a satellite pivoted on the mobile around a satellite axis parallel to the display axis and distant by a non-zero distance d1 from the display axis, a display zone, an indicator secured to the satellite and whose position relative to the display zone provides the information, a crown centered on the display axis and kinematically connected to the satellite, the display indicator being rotationally secured to the satellite and being located at a distance d2 from the satellite axis greater than or equal to the distance d1.

[0009] In other words, the mobile pivots in the opposite direction to that of the indicator. In the classic case where the information is displayed in a clockwise direction, the mobile therefore pivots in a counterclockwise direction. Compared to the prior art, the invention has the advantage of allowing the display of the information at the periphery of the display area by increasing the distance traveled by the indicator, which facilitates and increases the accuracy of reading the information. Alternatively, for a given display size, the invention makes it possible to propose a drive mechanism of reduced size.

[0010] According to an advantageous embodiment, the distance d2 is greater than the distance d1 + r which allows the indicator trajectory to be obtained entirely outside the circle defined by the crown.

[0011] Other advantages of the invention, objects of the dependent claims, will appear on reading the description. Brief description of the figures

[0012] Examples of implementation of the invention are indicated in the description illustrated by the appended figures in which: There figure 1 illustrates an embodiment of a display according to the invention, seen from the dial side. The figure 2 is a view of the mechanism of the figure 1 on the platinum side. The Figures 3a to 3c illustrate the display mechanism of the invention respectively at 12, 2 and 6 o'clock. The figure 4 illustrates the dial of a watch incorporating the display mechanism of the invention. The Figures 5 and 6 present, schematically, two variants in which the trajectory described by the indicator is a non-circular curve with a cyclic symmetry of order four and five respectively. Example(s) of embodiment of the invention

[0013] With reference to the attached figures 1 has 4, the display mechanism has a mobile 10which is rotated by the movement of a clockwork mechanism. In the example illustrated, this drive is obtained by the pinion 13 integral with the mobile 10 and cooperating with a wheel not illustrated of a clockwork movement, but other drive means are also possible.

[0014] The mobile 10 rotates around the display axis 17 which, as we will see later, is the central axis of the ellipse on which the display is made. The mobile 10 carries an axle or an eccentric bearing on which a satellite wheel is fixed 20, capable of rotating around the satellite axis 27. A needle 51 is mounted in solidarity with the satellite 20. The tip of the needle 51 constitutes an indicator 50 whose position relative to a display area 80 provides the information to be displayed. In the example shown, the display area 80is the dial of the timepiece. It has indexes 83 to determine the position of the indicator more easily and precisely 50 with reference to the display area 80.

[0015] A circular crown 30 is positioned concentrically to the display axis 17 and cooperates with the satellite 20. In a preferred variant, the crown 30 is fixed and the reduction ratio of this gear is 1÷2, in that the number of teeth of the crown 30 is double that of the satellite 20, so that when the mobile 10 rotates by a given angle in a direction relative to the display area, the satellite 20 rotates, relative to the mobile 10, of a double angle in the opposite direction.

[0016] The result of these two opposite rotations is that the satellite 20rotates, relative to the display area 80, at an angle equal and opposite to that of the mobile 10. The trajectory described by the indicator depends on its position relative to the axes of the display and the satellite. According to a particular aspect of the invention, the distance d2 between the indicator and the satellite axis 27 is greater than or equal to the distance d1 between the display axis 17 and the satellite axis 27. This results in the indicator 50 an elliptical trajectory in the opposite direction to that of the mobile 10.

[0017] If, as in the example shown, the distance d2 is greater than the sum of d1 and the radius r of the crown 30, the trajectory described by the indicator 50 is entirely external to the crown 30.

[0018] In the example presented, the mechanism allows time information such as the hour, minute or second to be displayed. Figures 3a to 3c illustrate three positions of the display with the dial partially shown to reveal the mechanism. In the Figure 3a , the satellite axis 27 is located at six o'clock, while the indicator 50 indicates twelve o'clock. The Figure 3b illustrates the position of the display at two o'clock: the mobile 10 rotated 60° counterclockwise and the needle 120° clockwise relative to the mobile 10. The result is a 60° clockwise rotation of the indicator 50, as expected for a two o'clock hand, with a counterclockwise circular movement to the right and up from the hand's origin.

[0019] There Figure 3c illustrates the display position at six o'clock. The mobile 10 has made a half-turn counterclockwise, and the hand a half-turn clockwise relative to the dial.

[0020] There figure 4illustrates a possible embodiment of a watch dial according to the invention. Advantageously, a cover 87 circular in shape is attached to the mobile 10 and has a collinear drilling with the satellite axis 27 for the passage of the needle axis 51. The cache 87 is located inside an opening in the dial and at the same level as it. The cover 87 allows the satellite wheel to be hidden 20 and the crown 30 to give the impression that the origin of the hand is "walking" in the central region of the dial.

[0021] It can be noted that the indicator 50 describes an ellipse with a major semi-axis a = d2 + d1 and a minor semi-axis b = d2 - d1.

[0022] The invention is also not limited to the case of a satellite wheel driving a needle. It is also possible to design variants in which the satellite 20itself presents a visible characteristic point, or drives a mobile with a characteristic point, or any other indicator or means of display.

[0023] Other non-circular curves can be obtained, within the scope of the invention, by choosing a transmission ratio other than 1÷2 between the crown 30 and the wheel 20. We can in fact produce a more general class of curves whose ellipse corresponds to the ratio 1÷2 between the crown 30 and the wheel 20 is only a special case. The Figure 5 shows an example in which the reduction ratio between the crown 30 and the satellite 20 is 3÷4 (for simplicity, only the primitive circles are shown). The satellite 20 carries an indicator 50describing a curve with cyclic symmetry of order 4, with four substantially straight sides and rounded corners. During a display cycle, the indicator 50 describes a trajectory 100 whose shape can be modified by varying the distance d2 relative to the dimensions of the wheels 20 And 30 : an elongation gives rise to a more rounded trajectory. Preferably, the distance d2 will be chosen so that the curve 100 is entirely outside the primitive circle of the crown 30, but this is not an essential characteristic of the invention.

[0024] Generally speaking, the mechanism allowing the indicator 50 describes a curve with a single loop and n+1 vertices is obtained when, during a display cycle, the satellite 20 performs n+1 rotations with reference to the mobile 10 while the mobile 10performs n rotations in the opposite direction with reference to the display area. This corresponds, when the crown 30 is fixed, at a ratio of n / (n+1) between the satellite wheel 20 and the crown. n=1 is the case presented on the figures 1 to 3 and gives an elliptical trajectory. n=2 would give a ratio of 2 / 3 and a triangular shaped trajectory. n=3 is the special case of the Figure 5 in which the mobile 10 describes three turns around the axis 17 when the satellite 20 performs 4 turns relative to the mobile 10.

[0025] We also understand that we could achieve other trajectories by choosing different ratios between the dimension of the crown 30 and the satellite 20,the ratios 4÷5, 5÷6 produce pentagonal, hexagonal, and so on trajectories that can adapt to the most diverse dial shapes.

[0026] The reduction ratio mentioned above can be expressed by non-consecutive whole numbers: in this case, the indicator 50 performs several revolutions around the display axis 17 during a display cycle and the trajectory 100 has several intersecting loops. The number of revolutions of the indicator corresponds to the difference between the number of rotations of the satellite relative to the mobile 10 and the number of rotations of the mobile 10 relative to the display area.

[0027] The example of the figure 6 shows a variant of the invention in which the ratio is 3÷5. During a display cycle, the satellite 20 rotates 5 times in reference to the mobile 10while it rotates three times around the axis 17. The indicator 50 thus describes a trajectory 100 comprising two revolutions and in the shape of a five-pointed star.

[0028] The invention allows for an infinite number of variations not shown. A ratio of 5÷7, for example, would produce an interlaced path with seven substantially straight sides and rounded corners. A ratio of 5 / 8 would produce a path with 3 revolutions and 8 vertices...

[0029] By increasing the number of revolutions, we increase the length of the trajectory 100 which improves the readability and precision of the information displayed.

[0030] In a variant not shown, the indicator 50 is located at a distance d2 equal to d1 and then describes a linear trajectory.

[0031] It is possible to combine the display of the invention with a retrograde mechanism in order to realize a retrograde display with an easily adaptable trajectory and position.

[0032] According to a particular aspect of the invention, the crown is not fixed, but is intended to be driven in rotation around the display axis 17 by the movement. This allows, for example, to reduce the size of the satellite wheel without modifying the kinematics of the indicator and to free up the center of the display. This also allows the creation of a two-input mechanism to display differential information such as the power reserve.

[0033] According to another variant of the invention not shown, the crown 30 has an external toothing meshing indirectly with the satellite 20 via a reversing pinion mounted on the mobile 10. The reversing pinion allows the satellite 20to turn in the opposite direction to that of the mobile 10. The use of external teeth for the crown 30 allows to simplify the mechanism in particular when the crown 30 is mobile.

[0034] The mechanism of the invention allows displays of original shapes to be produced with remarkable economy of means, and is therefore particularly well suited to the production of a watch with a refined design. Furthermore, the mechanism occupies a contained space in the center of the dial; it can therefore be advantageously combined with other peripheral displays with discs or small hands, to create a complicated watch. Reference numbers used in the figures

[0035] 10mobile 13drive wheel 17display axis 20satellite 27satellite axis 30crown 50indicator 51needle 80display area 83index 87cover amajor semi-axis bminor semi-axis d1axis distance 17, 27 d2distance from the indicator to the satellite axis 27

Claims

1. A mechanism for displaying information for a timepiece comprising: a mobile (10) intended to be driven in rotation by the movement of the timepiece about a display axis (17), a satellite (20) pivoted on the mobile (10) about a satellite axis (27) parallel to the display axis (17) and offset by a non-zero distance d1 (d1) from the display axis (17), a display area (80), a display indicator (50) comprising an end whose position relative to the display area (80) supplies the information, a crown (30) of radius r, centered on the display axis (17) and linked kinematically to the satellite (20), the end of the display indicator (50) being situated at a distance d2 (d2) from the satellite axis (27) greater than or equal to the distance d1, characterized in that said display indicator (50) is secured in rotation to the satellite (20), and in that the mobile element (10) pivots in a counterclockwise direction relative to the display area.

2. Display mechanism according to claim 1, wherein the distance d2 is greater than the distance d1+r.

3. Display mechanism according to one of the preceding claims, wherein the crown (30) is fixed with reference to the display area.

4. Display mechanism according to claim 1 or 2, wherein the crown (30) is intended to be driven in rotation by the movement about the display axis (17).

5. Display mechanism according to the preceding claim, wherein the information displayed is the power reserve.

6. Display mechanism according to one of the preceding claims, wherein the crown (30) comprises an internal toothing meshing with the satellite (20).

7. Display mechanism according to one of claims 1 to 6, wherein the crown (30) comprises an outer toothing meshing indirectly with the satellite (20) via a reversing pinion mounted on the mobile (10).

8. Display mechanism according to one of the preceding claims, arranged so that, during a display cycle, the satellite (20) performs n+1 rotations with reference to the mobile (10) whereas the mobile (10) performs n rotations in the opposite direction with reference to the display area.

9. Display mechanism according to the preceding claim, wherein n equals 1, 2, 3, 4 or 5.

10. Display mechanism according to one of the preceding claims, wherein the display indicator (50) is the end of a hand mounted on the satellite (20).

11. A retrograde display comprising a display mechanism according to one of the preceding claims.

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