Magnetic indexing system for display, and watch movement

Abstract

To provide a magnetic indexing system for a display.SOLUTION: A magnetic indexing system 10 comprises a structural element 11, a display 12 arranged movably relative to the structural element, and a pair of magnetic elements 13, 14 having an anchoring portion. By the anchoring portion, the first magnetic element 13 is fastened to the structural element and the second magnetic element 14 is fastened to the display. The magnetic elements are configured to cooperate with each other so as to generate positioning torque of the display adapted to maintain the display in a predetermined angular position with respect to the structural element. The magnetic elements comprises an interaction portion. By the interaction portion, the magnetic elements are intended to face each other. The interaction portion of the first or second magnetic element has a cross-section reduced relative to that of its anchoring portion.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to the field of watch manufacturing, and more particularly to watch movements. The present invention relates more particularly to a magnetic indexing system for a display.

[0002] The term "indexing" is well known to those skilled in the art as designating the act imposed on an object moving in a particular orientation. In the context of the present invention, indexing is performed so as to impose a linear position or an angular position on an object movable by translation or rotation, respectively.

Background Art

[0003] In the display mechanism of a wristwatch, the relative positioning of the display with respect to a reference point such as another display or a fixed structure is particularly important because it is a visible element. The problem of the relative positioning of the display is always troublesome to solve because even the slightest deviation is clearly visible to the user.

[0004] It is clear that proper positioning of the display guarantees quality, and incorrect positioning can greatly damage the image of the watch brand.

[0005]

[0006] For example, the "large date" date display device is well known, and this device includes two consecutive displays. These two consecutive displays each show a unit representing 10 and the current date. These two displays are oriented with respect to each other so as to give the illusion of a single display, or at least so that the numbers shown are aligned with each other. Since each display has its own drive mechanism to ensure that it rotates and remains in place, achieving proper relative positioning of these displays is particularly complicated. Among well-known indexing solutions, mechanical solutions can cause premature wear of the components constituting the drive mechanism and undesirable noise due to the friction generated and possible impact and / or kink phenomena.

Summary of the Invention

[0007] The present invention relates to a magnetic indexing system for a display to solve the above-mentioned drawbacks. This system includes a structural element, a display movably arranged with respect to the structural element, and a pair of magnetic elements including an anchor portion. By the anchor portion, the first magnetic element is fastened to the structural element and the second magnetic element is fastened to the display.

[0008] These magnetic elements are configured to cooperate with each other to generate a positioning torque of the display adapted to maintain the display at a predetermined angular position with respect to the structural element. These magnetic elements include interaction portions intended to face each other, and the interaction portion of the first or second magnetic element has a reduced cross-section compared to the cross-section of its anchor portion.

[0009] Thanks to these features, the present invention can compensate for indexing errors caused by mechanical play occurring between the teeth of the drive mechanism of the display.

[0010] Furthermore, the present invention enables the display to be repositioned, i.e., indexed, after an impact.

[0011] In a particular embodiment, the present invention may further include one or more of the following features, considered alone or in any technically possible combination.

[0012] In a particular embodiment, the interaction portion of the first or second magnetic element has an annular shoulder so as to form a central protrusion.

[0013] In a particular embodiment, the interaction portion of the first or second magnetic element has a triangular cross-section.

[0014] In a particular embodiment, the interaction portion of the first or second magnetic element has two opposite inclined side surfaces connected to each other by a central portion.

[0015] In certain embodiments, the interaction portion of the first or second magnetic element has a conical shape.

[0016] In certain embodiments, the interaction portion of the first or second magnetic element has an axially symmetric conical shape.

[0017] In certain embodiments, the interaction portion of the first or second magnetic element has a pyramid shape.

[0018] According to another object, the present invention relates to a timepiece movement including the indexing system and the roller display device described above, wherein the structural element is formed by a flange, and the display is formed by a roller including a support structure to which a flap is rotatably fastened.

Brief Description of the Drawings

[0019] Other features and advantages of the present invention will become apparent from the following detailed description given by way of non-limiting example with reference to the accompanying drawings.

[0020]

Figure 1

Figure 2

Figures 3a - 3d

[0021] Note that the figures are not necessarily drawn to scale for clarity.

Mode for Carrying Out the Invention

[0022] The present invention relates to a magnetic indexing system 10 for a display, and a preferred example of an application incorporated in a roller display device 20 will be described below.

[0023] For example, such a roller display device may follow that described in European Patent Application Publication No. 3627240.

[0024] The magnetic indexing system 10 according to the present invention includes a structural element 11 and a display 12 arranged to be movable relative to the structural element 11. In an example of the application of the present invention shown in FIGS. 1 and 2, the structural element 11 is formed by a flange, for example, intended to be fastened without freedom to a bridge or a plate. The display 12 is formed by a display roller including a support structure 120, the support structure 120 being intended to be mounted rotatably with respect to the structural element 11, and a flap 121 being rotatably fastened to the support structure 120. In another example of the application of the present invention, the structural element 11 may be formed by any structure of a timepiece movement, such as a bridge or a plate, and the display 12 may be formed by a disk, a strip, or the like.

[0025] The magnetic indexing system 10 also includes at least a pair of magnetic elements. Both of these magnetic elements are fastened to the structural element 11 and the display 12 respectively by anchor portions 130, 140. Specifically, a first magnetic element 13 of the pair of magnetic elements is fastened to the flange so as to face the locus of the flap 121, and at least a second magnetic element 14 of the pair of magnetic elements is fastened to the field of the flap 121. The anchor portions 130, 140 are cylindrical in shape, preferably axially symmetric cylinders. The first and second magnetic elements 13 and 14 are fastened to the structural element 11 and the display 12 respectively by driving or adhesion in a manner well known per se to those skilled in the art.

[0026] It should be noted that in this document, a plurality of different second magnetic elements 14 may successively form a pair of magnetic elements together with the same first magnetic element 13.

[0027] The first and second magnetic elements 13 and 14 are configured to cooperate with each other thanks to the establishment of magnetic attraction. Thereby, a positioning torque is generated for the display 12 adapted to maintain the display 12 at a predetermined angular position with respect to the structural element 11.

[0028] Advantageously, the first and second magnetic elements 13, 14 include interaction portions 131, 141 that extend to interaction ends intended to face each other on the opposite sides of their anchor portions 130, 140. The cross-section of the interaction portion 131 or 141 of the first or second magnetic element 13 or 14 is reduced compared to the cross-section of its anchor portion 130 or 140.

[0029] Thanks to this feature, the magnetic field lines of the first or second magnetic element 13 or 14 can be centered, thus ensuring that the flap 121 is properly positioned with respect to the flange. This feature also allows minimizing the attractive force between the first magnetic element 13 and the second magnetic element 14. This has the effect of minimizing the friction of the flap 121 in the support structure 120, and as a result, contributes to reducing the range of static equilibrium between the first magnetic element 13 and the second magnetic element 14.

[0030] Thanks to the present invention, the indexing accuracy of the flap 121 is substantially improved.

[0031] In some embodiments of the present invention, the interaction portion 131 or 141 of the first or second magnetic element 13 or 14 may have an annular shoulder 142 so as to form a central protrusion, as shown in FIG. 3a.

[0032] In the embodiments of the present invention shown in FIGS. 3b to 3d, the interaction portion 141 of the second magnetic element 14 has a triangular cross-section.

[0033] Specifically, in the example shown in FIG. 3b, the interaction part 141 of the second magnetic element 14 has two opposite inclined surfaces 143 connected to each other via a central part. The central part forms an interaction end and has a fragment shape.

[0034] In the embodiments shown in FIGS. 3c and 3d, the interaction part 141 of the second magnetic element 14 has a conical shape, and the interaction end is realized by a point. The interaction part 141 of the second magnetic element 14 may have an axially symmetric conical shape as shown in FIG. 3c, or may have a pyramid shape as shown in FIG. 3d.

[0035] It should be noted that the shape of the interaction part visible from FIGS. 3a to 3d described above here may also be applied to the interaction part 131 of the first magnetic element 13 alternatively or additionally.

[0036] In the only or each pair of magnetic elements, at least one of the magnetic elements is made of a hard ferromagnetic material. That is, it forms a permanent magnet. The other magnetic element may be made of a soft ferromagnetic material. Preferably, only the interaction part of the magnetic element made of the soft ferromagnetic material has a reduced cross section.

[0037] More generally, it should be noted that the implementation and manufacturing methods discussed above here are described as non-limiting examples, and thus other variations are also conceivable.

[0038] It should be noted that the air gap, that is, the distance between the pair of first magnetic elements 13 and the second magnetic element 14, is in the range of, for example, 10 to 100 μm, or 20 to 40 μm.

Claims

1. A magnetic indexing system (10) for a display (12), comprising: The present invention relates to a method for manufacturing a magnetic display comprising: a structural element (11); an indicator (12) movably arranged with respect to the structural element (11); and a pair of magnetic elements (13, 14) including anchor portions (130, 140) by which a first magnetic element (13) is fastened to the structural element (11) and a second magnetic element (14) is fastened to the indicator (12), the magnetic elements (13, 14) being configured to cooperate with each other to generate a positioning torque of the indicator (12) adapted to maintain the indicator (12) in a predetermined angular position with respect to the structural element (11). a magnetic indexing system (10) including an interacting portion (131, 141) by which they are intended to face each other, the interacting portion (131, 141) of the first or second magnetic element (13, 14) having a cross-section that is reduced relative to the cross-section of its anchor portion (130; 140), the interacting portion (131; 141) of the first or second magnetic element (13; 14) having an annular shoulder (142) forming a central protrusion or having a triangular shaped cross-section.

2. 2. The indexing system according to claim 1, wherein the interacting portion (131; 141) of the first or second magnetic element (13; 14) has two opposing inclined surfaces (143) connected to each other by a midpoint.

3. 2. The indexing system according to claim 1, wherein the interacting portion (131; 141) of the first or second magnetic element (13; 14) has a conical shape.

4. 4. An indexing system according to claim 3, wherein the interaction part (131; 141) of the first or second magnetic element (13; 14) has an axisymmetric conical shape.

5. 4. An indexing system according to claim 3, wherein the interacting part (131; 141) of the first or second magnetic element (13; 14) has a pyramidal shape.

6. A clock movement comprising an indexing system according to claim 1 and a roller indicator (20), wherein the structural element (11) is formed by a flange and the indicator (12) is formed by a roller comprising a support structure (120) to which a flap (121) is fastened for rotational movement.

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