EP0663631A1 - Timepiece displaying the part of earth visible from the moon - Google Patents

Abstract

The watch includes a conventional analogue display with an hour hand (22) and a minute hand (23) moving over the face (25), and a correcting knob (27) on the side. The face carries a view of the terrestrial globe in polar projection, centred on the axis of the hands. A further indicator comprises a T-shaped, with the cross bar of the T extending along the full diameter of the watch face, and the shorter stem (27b) ending in a crescent shape (27b). This bar turns with a period of 24 hours, 28 minutes 45.78 seconds, being the period of rotation of the earth as seen from the moon.

Description

The present invention relates to a timepiece capable of indicating which part of the terrestrial globe is visible from the Moon, and in particular a timepiece capable of indicating the Earth phases as they would be perceived by an astronaut contemplating the sky from the Moon.

We already know many timepieces intended to indicate the phases of the Moon, but the problem of indicating the phases of the Earth involves an additional technical difficulty.

A person skilled in the art knows that the rhythm with which the phases of the Moon are linked and the rhythm with which the phases of the Earth are linked are identical and that, moreover, the phases of the Moon and the phases of the Earth are exactly in opposition. At first glance, making a watch indicating the phases of the Earth, using cogs conventionally used to indicate the phases of the Moon, therefore presents no difficulty. However, unlike the Moon which always presents the same face to the Earth, the latter, as we know, rotates around its axis at the rate of a rotation per 24 hours. An astronaut located on the Moon therefore sees gradually changing the topography of the continents present in the visible part of the Earth. This rotation effect which combines with the sequence of Earth phases has no equivalent with the Moon.

An object of the present invention is therefore to provide a timepiece capable of indicating which part of the surface of the terrestrial globe is visible from the Moon.

To this end, the present invention relates to a timepiece comprising a time base, a dial and means for displaying the time controlled by said time base, characterized in that it comprises astronomical display means provided for indicating on a map of the terrestrial globe, visible in at least part of said dial, the part of the surface of the Earth visible from the Moon.

Thanks to these characteristics, the wearer of the timepiece can, by consulting it, obtain a precise indication of the part of the Earth visible from the Moon.

According to the preferred embodiment of the present invention, the timepiece further comprises phase display means for indicating on said map the district of the Earth lit by the Sun.

Thanks to these characteristics, the wearer of the timepiece can, at any time, obtain realistic information on the view of the Earth that an astronaut would have from the surface of the Moon.

According to a first variant of the preferred embodiment of the invention, the astronomical display means of the timepiece are formed by a rotating disc mounted under the dial coaxially with the hands, this disc carrying at its periphery a circular series of views of the Earth retracing a rotation of a full revolution of the Earth around its axis, these views appearing successively through a window of the dial as the disc rotates, so that a rotation of the disc from a given angle results in an equivalent rotation of the Earth as it appears in the window.

According to a second variant of the preferred embodiment of the invention, the Earth map is represented on the dial in polar projection, and the astronomical display means are formed by a mobile provided to rotate in front of the dial around a axis coincides with the pole of said card, this mobile comprising a line or axis extending prependicularly on either side of the axis of rotation, so as to appear on the card a line of demarcation between the hemisphere of Earth visible from the Moon and the other hemisphere.

• les figures 1a et 1b sont deux schémas illustrant le principe de fonctionnement d'un premier exemple de réalisation de la présente invention;
• la figure 2 est une vue de dessus d'un deuxième exemple de réalisation de la présente invention.

Other characteristics of the present invention will become apparent during the description which follows, given solely by way of example and made with reference to the appended drawings in which:

• Figures 1a and 1b are two diagrams illustrating the operating principle of a first embodiment of the present invention;
• Figure 2 is a top view of a second embodiment of the present invention.

The timepiece shown in FIGS. 1a and 1b is a wristwatch 1 conventionally comprising an hour hand 2 and a minute hand 3 intended to be actuated by a movement (not shown) so as to rotate in front of a dial 5, a crown for setting the time 7 is also provided in particular to enable the respective positions of the hour hands 2 and minutes 3 to be corrected. As can be seen in FIG. 1b, the dial 5 of watch 1 and provided with '' a window 9, at twelve o'clock, through which may appear graphic indications 11 carried by a ring 13 arranged to turn behind the dial.

The rotating ring 13 is visible in Figure 1a. In watch 1 according to the invention, it occupies the position generally occupied by the date disc in a conventional watch. This rotating ring constitutes in the present embodiment, the astromomic display means provided for indicating the part of the surface of the Earth visible from the Moon. To this end, it carries as graphic indications twelve views of the Earth (three of these being referenced 11 in FIG. 1a). These views of the Earth 11 form a circular sequence representing the complete turn that the earth performs around its axis in the space of a day. The ring shown in Figure 1a having twelve views, the transition from one view to the next corresponds to a twelfth of a turn, that is to say at 30 °.

The rotating ring 13 carrying the views of the Earth, can conventionally be provided with an internal toothing 12 and a jumper spring (not shown) to allow the movement to drive it step by step, so as to make successive in the window 9 the views of the Earth 11. The view of the Earth visible in the window being intended to represent the Earth as it is seen from the Moon, the ring 13 must make a turn substantially every 24 hours, 48 minutes and 45.78 seconds. To actuate the ring 13, it is naturally possible to provide in the movement an additional motor controlled by an electronic circuit to drive it directly at the appropriate rate of one step every 2 hours, 4 minutes and approximately four seconds.

correspond presque exactement au rapport entre la durée d'une rotation de la Terre par rapport au Soleil, c'est à dire 24 heures, et la durée d'une rotation de la Terre par rapport à la Lune, c'est à dire 24 heures 48 minutes et 45,48 secondes. Grâce aux rapports d'engrenages indiqués ci-dessus, l'homme du métier pourra, sans problème, concevoir un rouage approprié.It is also possible to use, to drive the ring 13, a cynematic chain having, for example, its origin on an hour wheel secured to the hour hand. Indeed the gear ratio
$$\frac{\text{10}}{\text{21}}\text{x}\frac{\text{47}}{\text{29}}\text{x}\frac{\text{71}}{\text{53}}$$

almost exactly corresponds to the ratio between the duration of a rotation of the Earth relative to the Sun, i.e. 24 hours, and the duration of a rotation of the Earth relative to the Moon, i.e. 24 hours hours 48 minutes and 45.48 seconds. Thanks to the gear ratios indicated above, the person skilled in the art will be able, without problem, to design an appropriate gear train.

We have now described, for this first exemplary embodiment, the astronomical display means indicating the part of the surface of the Earth visible from the Moon. We will now describe, in relation to this same embodiment, the phase display means intended to indicate the quarter of the Earth lit by the Sun.

As can be seen in FIG. 1a, the watch further comprises a phase disc 15 which is mounted between the ring 13 is the dial 5. This disc 15 is made of a transparent material, for example glass, and it has on its surface two zones of circular shapes located diametrically opposite one another, inside which the transparent material has been treated to darken it (these zones are both referenced 17 in FIG. 1a) . As seen in Figure 1a, the phase disc 15 is mounted to rotate about an axis (not referenced) which is located a short distance from the window 9, so that during the rotation of the disc , the two dark circles 17, pass in turn through this window.

The ring 13 being, as has been said, disposed under the phase disk 15 made of transparent material. The views of the Earth it carries are visible through the window 9 in transparency. When one of the dark circles 17 passes through the window 9, it constitutes a shadow which can partially or totally cover the view of the earth 11. Thanks to this arrangement, the progressive rotation of the phase disc 15 varies the relative importance of the part of the Earth's view visible in transparency compared to the obscured part. This arrangement is shown in Figure 1b. By rotating the phase disk 15 at an appropriate speed, an easily visible representation of the variation in the size of the quarter of Earth lit by the Sun during a lunation is obtained.

As we have already said, the phases of Earth seen from the Moon have the same period as the phases of Moon seen from Earth, i.e. 29.530588402 days. In accordance with what is conventional in watches with moon phases, in the present example, a gear train driving the phase disc 15 of one revolution every 59 days is used for the Earth phases. This cog can be identical to those commonly used for phase watches Moon, we will not describe it here. The phase 15 disc comprising, as we have seen, two diametrically opposite dark circles, the Earth will be masked by a dark circle twice per revolution of the disc 15. Under these conditions, this disc performing one revolution in 59 days, the Land phases will have a period of 29.5 days.

The embodiment of the present invention which we have just described allows, as we have just seen, to indicate simultaneously in a single dial window the phase of the Earth and the part of the surface of the globe visible from the Moon .

Referring now to Figure 2, we will describe a second embodiment of the present invention. The timepiece 21 represented in this latter figure is also a wristwatch conventionally comprising a 22 hour hand and a 23 minute hand actuated by a movement (not shown) to turn in front of a dial 25, a setting crown. time 27 is still provided in particular to allow the respective positions of hands 22 and 23 to be corrected.

As can be seen in FIG. 2, the dial 25 carries a view of the terrestrial globe in polar projection. This view extends substantially over the entire surface of the dial and is centered on the axis of the hands 22 and 23. We can also see in the figure a third mobile 27 formed of two parts 27a and 27b perpendicular to each other . This mobile 27, which has substantially the shape of a T, is mounted to rotate, in front of the dial, coaxially with the hands 22 and 23.

The part 27a of the mobile 27, which forms the bar of the T, is constituted by a line or an axis extending perpendicularly on either side of its axis of rotation. The line formed by the part 27a of the mobile forms, as can be seen in FIG. 2, a dividing line dividing the terrestrial globe represented on the dial 25 into two hemispheres. The mobile is intended for be trained at the rate of one revolution every 24 hours, 48 minutes and 45.78 seconds, that is to say at a rate corresponding to the rate of rotation of the Earth as perceived from the Moon. Under these conditions, the first part 27a of the mobile can permanently indicate the limit between the hemisphere of the Earth visible from the Moon and the other hemisphere.

The second part 27b of the mobile, which forms the leg of the T, is constituted by a needle or an arrow and is provided, in the present embodiment, for indicating on the map of the terrestrial globe the meridian vertically of which the Moon, so as to indicate which of the two hemispheres of the Earth separated by part 27a of the mobile is visible from the Moon.

We have now described, for this second exemplary embodiment, the astronomical display means indicating the part of the surface of the earth visible from the moon. We will now describe, in relation to this same exemplary embodiment, the phase display means intended to indicate the quarter of the earth lit by the Sun.

As can be seen in FIG. 2, the timepiece 21 also includes an indicator member 29 constituted by a transparent disc. This transparent disc is designed to rotate above the dial 25 coaxially with the hands 22 and 23 and the mobile 27.

It can also be seen in FIG. 2 that the disc 29 is subdivided into two symmetrical halves 29a and 29b. the transparent material forming the disc having, in the first half 29a, been tinted so as to darken it. Thus, the image of the part of the Earth seen in transparency through the half 29a of the disc 29 appears obscured, while the image of the part of the Earth visible through the other part 29b of the disc appears illuminated.

The disc 29 is designed to be driven by the movement of the watch at the rate of one revolution per 24 hours, that is to say at a rhythm corresponding to the rhythm of the alternation of day and night. In this way, the disc 29 can be used to indicate the part of the Earth lit by the Sun, the part of the image of the Earth visible through the clear part 29a of the disc corresponding to the part lit by the Sun, and the part of the image of the Earth visible through the dark part 29b of the disc corresponding to the part of the Earth where it is dark.

The combination of the information provided by the astronomical display means (here the mobile 27) and the phase display means (here the transparent disc 29) constitutes for the wearer of the watch an indication, immediately legible, as to the size of the Earth district lit by the Sun. In fact, the size of the light district of Terre corresponds to the proportion of the hemisphere visible from the Moon which is not obscured by the dark half 29a of the disc 29.

Claims (13)

Timepiece comprising a time base, a dial (5; 25) and time display means (2,3; 22,23) controlled by said time base, characterized in that it comprises in addition astronomical display means (13; 27) provided for indicating on a map of the terrestrial globe (11), visible in at least part of said dial (5; 25), the part of the surface of the Earth visible from the moon. Timepiece according to claim 1, characterized in that it further comprises phase display means (15, 17; 29) for indicating on said map the size of the Earth district lit by the Sun. Timepiece according to claim 1, characterized in that said astronomical display means (11,13) are formed by a rotating disc (13) mounted under the dial (5) coaxially with the hands (2,3), said disc (13) carrying at its periphery a circular series of views of the Earth (11) retracing a rotation of a full revolution of the Earth around its axis, said views appearing successively through a window (9) of the dial ( 5) as the said disk (13) rotates, so that a rotation of the disk by a given angle results in an equivalent rotation of the Earth as it appears in the window. timepiece according to claim 3, characterized in that said disc (13) is controlled by said time base to make a revolution substantially every 24 hours, 48 minutes and 45.78 seconds. Timepiece according to one of claims 3 or 4, characterized in that said disc (13) is designed to move in successive steps, each step bringing a new view of the Earth (11) in the window (9) . Timepiece according to claim 3, characterized in that
said phase display means are formed by a semi-transparent mask (15,17) secured to a rotating axis, said mask being designed to periodically pass through the window (9) so as to at least partially mask the view of Earth (11). Timepiece according to claim 6, characterized in that said mask (15,17) has a rotation symmetry of order 2 and that consequently, it masks twice the view of the Earth (11) during each rotation of said rotating axis. Timepiece according to claim 7, characterized in that
said rotary axis is controlled by said time base to make a revolution every 59 days approximately. Timepiece according to claim 1, characterized in that said map of the terrestrial globe is produced on the dial (25) in polar projection, in that said astronomical display means are formed by a mobile (27) mounted to rotate in front of the dial (25) around an axis coincident with the pole of said card and in that said mobile (27) has a straight line (27a) extending on either side of the axis of rotation for appear at all times on the said card the dividing line between the hemisphere visible from the Moon and that which is hidden. Timepiece according to claim 9, characterized in that said mobile (27) further comprises an arm (27b) extending perpandicularly to said line (27a) to indicate, on said map, the direction of the Moon and to indicate at the same time which of the two hemispheres separated by said line (27a) is that visible from the Moon. Timepiece according to claim 9 or 10, characterized in that said mobile (27) is controlled by said time base to perform a revolution approximately every 24 hours, 48 minutes and 45.78 seconds. Timepiece according to claim 9, 10 or 11, characterized in that said phase display means are formed by a transparent disc (29) mounted to rotate in front of the dial (25), concentrically with said mobile (27) , and in that one half (29a) of said transparent disc is tinted so that a user who looks at said map of the globe through the transparent disc (29) can distinguish a hemisphere plunged in shadow and a hemisphere enlightened. Timepiece according to claim 12, characterized in that said transparent disc (29) is controlled by said time base to perform one revolution every 24 hours.

Images