EP0181809B1 - Time piece with a calendar display mechanism - Google Patents

Description

The present invention relates to improvements to display devices of the date type, used on devices intended to indicate time, such as, in particular, watches.

Usually, these devices include a window provided in the watch face, through which the user can observe the signs to be displayed, arranged on a disc driven in rotation by the movement of the watch.

A major drawback inherent in this type of display, however, lies in the difficulty of perceiving the signs displayed, since the observer is not strictly in the axis of the window. In addition, the part of the image visible through the window is not, beyond a given incidence of light rays, fully illuminated.

It has certainly been proposed, to partially remedy these two drawbacks, to reduce the apparent thickness of the dial by making chamfers on the internal edges of the window. However, this arrangement is not entirely satisfactory, especially since, for mechanical reasons (warping of the rotating disc), it is necessary to provide a relatively large space between the dial and the rotating disc.

It has been suggested, in order to improve the ease of reading, to enlarge the dimensions of the signs displayed by means of a magnifying glass fixed on the crystal of the watch or forming an integral part thereof (CH-A-15 009/73 ) In addition to the fact that this solution does nothing to remedy the defects in masking and penumbra, it further reduces the angle under which it is possible for the user to read.

Finally, it has been proposed, to remedy the lighting and masking faults mentioned above, to use a bundle of coherent optical fibers, one end of which is disposed near the mobile support of the watch and the other end of which is flush a visible side of an element of this watch. Such a watch is described, for example, in FR-A-2,011,614.

• La figure 1 est une coupe axiale partielle d'une montre d'un type connu à système dateur;
• Les figures 2 et 3 sont des coupes analogues à celle de la figure 1 de deux formes de réalisation d'une montre selon l'invention;
• La figure 4 est une coupe selon la ligne IV - IV de la figure 3.

This type of watch is the subject of the present invention and we will begin by recalling its characteristics, with reference to FIG. 1 of the accompanying drawings, the other figures of which illustrate embodiments of the invention, which will be referred to in the remainder of this description. In these drawings:

• Figure 1 is a partial axial section of a watch of a known type with date system;
• Figures 2 and 3 are sections similar to that of Figure 1 of two embodiments of a watch according to the invention;
• Figure 4 is a section along the line IV - IV of Figure 3.

The watch shown in Figure 1 is a watch of a known type, in which a disc 44, carrying on its upper face the signs to be displayed, is rotated by the movement of the watch and scrolls during its rotation in view of a window 36 provided in the dial 24 and in which is housed a bundle 38 of coherent optical fibers.

The upper part is engaged in a light 46 formed in the crystal 22 of the watch, on the outer surface of which is flush with the upper end of said beam.

The present invention aims to improve the sharpness of the image transmitted by the fiber bundle of such a watch, by providing an optical bridge of a low viscosity liquid, interposed between the support of the signs to be displayed and the adjoining end. of the optical fiber bundle, thus avoiding multiple spurious reflections at the surfaces of the fiber bundle and the observation surface.

The invention also aims to avoid the risk of scratches on the adjacent surfaces, during the movement of the support of the signs to be displayed, since it is thus possible to distance them sufficiently without risking harming the sharpness.

The invention finally aims, in the case where these two surfaces come into contact, to avoid the formation of scratches, by ensuring lubrication of the surfaces in contact.

To this end, the subject of the invention is a watch or the like comprising a display device, of the type in which the signs to be displayed are carried by a mobile support and are perceived by an observer through a window provided in a part of the watch and in which a bundle of coherent optical fibers is engaged, so that one end of the said bundle is disposed near the mobile support, while its other end is flush with a visible face of an element of the watch, characterized in that a liquid film of low viscosity and ensuring an optical bridge between the fibers and the mobile support is interposed between said mobile support and the contiguous end of the bundle of fibers, and in that said liquid is disposed on the surface of said support mobile or in an annular bowl of said mobile support.

In a particularly advantageous embodiment of the invention, the bundle of fibers is mounted "floating" on the film of liquid deposited on the disc, its lateral support being provided by the internal walls of the window. It is noted that in addition to its simplicity, this embodiment has the advantage of ensuring a constant spacing between the bundle of fibers and the disc. This results in practically total elimination, on the one hand, of the risks of scratches and, on the other hand, of irregularities in the image observed due to the differences in distance between the disc and the bundle of fibers.

This liquid could simply be an oil of the type used in watchmaking for the lubrication of small movements.

FIGS. 2 and 3 illustrate two forms of implementation of the invention, in a watch of the type of that of FIG. 1.

In these two embodiments, the bundle 38 of optical fibers is always housed in a window 36 of the dial 24, but an optical bridge, intended to improve the quality of the reading of the displayed signs, is provided between the end of the beam 38 and the disc 44.

In the case of FIG. 2, the beam 36 is integral with the dial 24 and the face of the rotating disc 44 facing the lower end of the said beam is coated with a liquid 48 with a low viscosity index, for example an oil for movement timepieces of the type sold by the MOBIUS company under the reference N ° 9027. The oil film is in contact with the adjacent end of the beam 38 and thus ensures an optical bridge between the fibers and the disc 44. It eliminates or also reduces the risk of scratches due to accidental contact of the fiber bundle and the dial.

In the variant of FIG. 3, the liquid 48 is placed in an annular bowl of the disc 44, in which the lower end of the bundle 38 of optical fibers rests, and this bundle, instead of being rigidly secured to the dial 24 is mounted floating in the window 36, the side walls of which serve simply to guide and maintain the bundle 38. In this case, the bundle 38 of fibers can move under the stress of the disc 44 while maintaining a constant distance therefrom. This avoids any risk of scratches on the disc and / or the end face of the fiber bundle.

The invention therefore provides improvements which are simple and easy to implement in watches or the like, equipped with a mobile display system of the date type, with a view to improving the observation of the indications carried by the display system.

Claims (2)

1. Watch or similar comprising a display device, of the type in which the signs to be displayed are carried by a mobile support (44) and are seen by an observer through a window (36) formed in a part of the watch and in which a bundle (38) of coherent optical fibres is engaged so that one end of said bundle is disposed in the vicinity of the mobile support (44), whereas its other end is flush with a visible face of an element of the watch, characterized in that a low viscosity liquid film providing an optical bridge between the fibres and the mobile support is inserted between said mobile support (44) and the contiguous end of the optical fibre bundle (38), and in that said liquid is disposed on the surface of said mobile support (44) or in an annular dish (48) of said mobile support (44).

2. Watch according to claim 1, characterized in that said fibre bundle (38) is mounted floating on said liquid.

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