Magnetic indexing system for display devices, and clock 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 visible to the user.

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

[0005] 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 a predetermined position, achieving proper relative positioning of these displays is particularly complicated.

[0006] Among well-known indexing solutions, mechanical solutions can cause premature wear of the components constituting the drive mechanism due to the friction generated and the possible impact and / or kink phenomena, and can also cause undesirable noise.​ [Overview of the initiative]

[0007] The present invention solves the aforementioned drawbacks and, for this purpose, relates to a magnetic indexing system for an indicator. The system includes a structural element, an indicator movably arranged with respect to the structural element, and a pair of magnetic elements including an anchor portion. The anchor portion fastens the first magnetic element to the structural element and the second magnetic element to the indicator.

[0008] These magnetic elements are configured to cooperate with each other to generate a positioning torque for the indicator, adapted to maintain the indicator at a predetermined angular position relative 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 between the teeth of the indicator's drive mechanism.

[0010] Furthermore, the present invention makes it possible to rearrange the indicator after an impact, i.e., to index it.

[0011] In certain embodiments, the present invention may further include one or more of the following features, which may be considered individually or in any technically possible combination:

[0012] In certain embodiments, the interaction portion of the first or second magnetic element has an annular shoulder portion that forms a central projection.

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

[0014] In certain embodiments, the interaction portion of the first or second magnetic element has two opposite inclined sides connected to each other by a midline.

[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 axisymmetric conical shape.

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

[0018] To another objective, the present invention relates to a clock movement including the aforementioned indexing system and a roller display device, wherein the structural elements are formed by flanges, and the display device is formed by rollers including a support structure to which flaps are rotatably fastened. [Brief explanation of the drawing]

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

[0020] [Figure 1] This is a perspective view of a roller display device in which the magnetic indexing system according to the present invention is integrated, as an example of an application of the present invention. [Figure 2] Figure 1 is a perspective view of the display unit of the display device. [Figures 3a-3d] Figures 3a to 3d schematically show perspective views of a pair of magnetic elements of an indexing system according to an embodiment of the present invention.

[0021] Please note that the diagrams are not necessarily drawn to scale for the sake of clarity. [Modes 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 be according to 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 intended to be fastened without freedom, for example, to a bridge or a plate. The display 12 is formed by a display roller including a support structure 120, and the support structure 120 is intended to be mounted rotatably relative to the structural element 11, and a flap 121 is fastened rotatably 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 watch movement, such as a bridge or a plate, and the display 12 may be formed by a disk, a strip, etc.

[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, the 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 the 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 due to the establishment of magnetic attraction. Thereby, a positioning torque with respect to the display 12 adapted to maintain the display 12 at a predetermined angular position with respect to the structural element 11 is generated.

[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 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] Due to this feature, the magnetic field lines of the first or second magnetic element 13 or 14 can be centered, ensuring that the flap 121 is properly positioned with respect to the flange. This feature also allows minimizing the attraction 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] More specifically, in the example shown in Figure 3b, the interaction portion 141 of the second magnetic element 14 has two opposite inclined surfaces 143 connected to each other via a central portion. The central portion forms an interaction end and has a fragment shape.

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

[0035] It should be noted that the shapes of the interaction parts described above and visible in Figures 3a to 3d can also be applied to the interaction part 131 of the first magnetic element 13, either alternatively or additionally.

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

[0037] Furthermore, it should be noted that the implementation and manufacturing methods discussed above are described as non-limiting examples, and therefore other variations are conceivable.

[0038] It should be noted that the air gap, i.e., the distance between the pair of first magnetic elements 13 and second magnetic elements 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 unit (12), The structure includes a structural element (11), a display unit (12) movably arranged relative to the structural element (11), and a pair of magnetic elements (13, 14) including anchor portions (130, 140), wherein the first magnetic element (13) is fastened to the structural element (11) by the anchor portions (130, 140) and the second magnetic element (14) is fastened to the display unit (12), and the magnetic elements (13, 14) cooperate with each other to generate a positioning torque for the display unit (12) that is adapted to maintain the display unit (12) at a predetermined angular position relative to the structural element (11), and the magnetic A magnetic indexing system (10) wherein the magnetic elements (13, 14) include interaction portions (131, 141) which are intended to cause the magnetic elements (13, 14) to face each other, the interaction portions (131, 141) of the first or second magnetic elements (13, 14) have a radial cross-section which is reduced compared to the radial cross-section of the anchor portions (130, 140), and the interaction portions (131, 141) of the first or second magnetic elements (13, 14) have annular shoulder portions (142) which form a central projection, or have a triangular axial cross-section.

2. The magnetic indexing system (10) according to claim 1, wherein the interaction portion (131, 141) of the first or second magnetic element (13, 14) has two opposing inclined surfaces (143) connected to each other by a midline when the interaction portion (131, 141) has the triangular axial cross-section.

3. The magnetic indexing system (10) according to claim 1, wherein the interaction portion (131, 141) of the first or second magnetic element (13, 14) has a conical shape when the interaction portion (131, 141) has the triangular axial cross-section.

4. The magnetic indexing system (10) according to claim 3, wherein the interaction portions (131, 141) of the first or second magnetic elements (13, 14) have an axisymmetric conical shape.

5. The magnetic indexing system (10) according to claim 1, wherein the interaction portion (131, 141) of the first or second magnetic element (13, 14) has a pyramidal shape when the interaction portion (131, 141) has the triangular axial cross-section.

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

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