MECHANISM FOR A WATCH MOVEMENT

Abstract

Mechanism for a watch movement (1) comprising a cam (5), a rack (3) driven by the cam (5), a retrograde mobile (20) driven by said rack (3) and bearing a retrograde indicator (2) for displaying a first item of time information, the rack (3) and the retrograde mobile (20) being arranged in such a way as to rotate in the same direction. A jumping hour display ring is synchronized with the returns of the retrograde display.

Claims

1. A mechanism for a watch movement comprising: a cam; a rack driven by said cam; a retrograde mobile driven by said rack and bearing a retrograde indicator for displaying a first item of time information; wherein the rack and the retrograde mobile are arranged in such a way as to rotate in the same direction.

2. The mechanism as claimed in claim 1, one end of said rack comprising an opening fitted with an internal toothing, said retrograde mobile being driven by said internal toothing.

3. The mechanism as claimed in claim 1, comprising: a jumping display ring to display a second item of time information, said jumping display ring comprising an internal toothing; said rack comprising a drive member collaborating with said internal toothing to drive said jumping display ring in rotation in a jumping way.

4. The mechanism as claimed in claim 3, in which said internal toothing comprises a plurality of teeth with asymmetric flanks, said rack drive member being arranged in such a way as to butt against one flank of a tooth of the internal toothing and to drive the jumping display ring when the rack is rotating in the counterclockwise direction, and to slide along another flank of a tooth of the internal toothing, or so as to not be in contact with the internal toothing when the rack is rotating in the clockwise direction.

5. The mechanism as claimed in claim 3, said drive member being mounted on the rack by means of an axis allowing it to pivot.

6. The mechanism as claimed in claim 5, comprising a spring mounted on said rack and applying force to press said drive member against said internal toothing.

7. The mechanism as claimed in claim 3, in which said first item of time information is the current hour, and said second item of time information is the current minute.

8. A method for displaying items of time information by means of a watch movement as claimed in claim 7, comprising the following steps: the movement drives said cam, said cam drives said rack, said rack drives said retrograde mobile and the retrograde indicator, said rack drives said jumping display ring in order to display the current hour, wherein said rack, said retrograde mobile and the indicator rotate in the same direction.

9. The method as claimed in claim 8, in which said jumping display ring is driven in rotation in a jumping way by a drive member mounted on said rack.

10. The method as claimed in claim 8, in which the clockwise rotation of said rack drives the clockwise rotation of the retrograde mobile and the counterclockwise rotation of said jumping display ring which displays the current hour.

11. The method as claimed in claim 8, in which, when said cam rotates in the counterclockwise direction and drives the rotation of said rack in the clockwise direction, said rack, by rotating in the clockwise direction, drives the rotation in the same direction of the retrograde mobile, of the indicator and of the drive member, and said drive member moves along a flank of the internal toothing connected with the jumping display ring without driving the rotation of said jumping display ring.

12. The method as claimed in claim 8, in which, when said first end of the rack reaches the peak of said cam, the drive member is butting against a flank of the internal toothing connected with the jumping display ring.

13. The method as claimed in claim 8, in which, when the first end of the rack drops from the peak of said cam, the second end of the rack is driven in rotation in the counterclockwise direction near-instantaneously, causing the near-instantaneous rotation in the same direction of the retrograde mobile, of the indicator, of the drive member and of the jumping display ring.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0059] Exemplary embodiments of the invention are indicated in the description which is illustrated by the attached figures in which:

[0060] FIG. 1 illustrates a view from above of the key components of the mechanism according to the invention.

[0061] FIG. 2 illustrates a view from above of the key components of the mechanism according to the invention at minute 0.

[0062] FIG. 3 illustrates a view from above of the key components of the mechanism according to the invention at minute 17.

[0063] FIG. 4 illustrates a view from above of the key components of the mechanism according to the invention at minute 35.

[0064] FIG. 5 illustrates a view from above of the key components of the mechanism according to the invention at minute 59.

[0065] FIG. 6 illustrates a view from above of the key components of the mechanism according to the invention at minute 60.

[0066] FIGS. 7 to 10 illustrate a number of views from above of the key components of the mechanism according to the invention during the jump from minute 60 to minute 0.

[0067] FIG. 11 illustrates a view from above of the key components of the mechanism according to the invention at minute 0.

[0068] For the sake of clarity, the figures do not depict the movement that drives the mechanism according to the invention.

EXAMPLE(S) OF EMBODIMENT(S) OF THE INVENTION

[0069] FIG. 1 illustrates an example of a retrograde mechanism 1 according to the invention. It comprises a retrograde indicator 2 depicted in the form of a minute hand in this embodiment. The retrograde minutes indicator 2 is mounted on the axis of the retrograde mobile 20. The retrograde mobile 20 comprises an external toothing 200.

[0070] The rack 3 has a first end 31 pressing against the periphery of the snail cam 5 by virtue of a rack spring 33. The second end 32 of the rack 3 comprises an oblong opening equipped with an internal toothing 320. The rack 3 pivots under the action of the snail cam from the pivot point. During this pivoting, the internal toothing 320 of the second end of the rack 32 engages with the external toothing 200 of the retrograde mobile 20 so that the retrograde indicator 2 borne by the retrograde mobile 20 turns in the same direction as the second end of the rack 32. The movement of the rack is transmitted to a drive member, here consisting of a tooth 4 articulated to the second end of the rack 32 by means of the axis 41. A return spring 42 applies a return force to the tooth 4 in order to press it against the toothing 610.

[0071] The first end of the rack 31 follows the rotation of the snail cam 5 borne by a driving release wheel 52. This driving release wheel 52 is driven by a wheel of the geartrain in such a way that the minutes indicator 2 travels over the minutes scale 11 (FIGS. 2 to 11) in 60 minutes (or 60 minutes minus the return time).

[0072] In this embodiment, the mechanism 1 comprises a jumping display ring 60 bearing the hour indications 6 allowing the current hour to be displayed in a window 10 (FIGS. 2 to 11).

[0073] The jumping display ring 60 is driven by the smaller-diameter drive ring 61. In an alternative form which has not been illustrated, it is also conceivable for the hour indications 6 to be positioned directly on the drive ring 61 or on a ring of the same diameter.

[0074] The drive ring 61 comprises an internal toothing 610 with a plurality of teeth around the entire internal periphery. The spacing between the teeth is even and there is no missing tooth. The teeth have two asymmetric flanks 6100 and 6101. The first flank 6100 is almost parallel to the diameter of the drive ring 61 and allows the drive ring 61 to be driven by means of the drive member (tooth) 4. The tooth 4 acts as a drive member for the jumping hours display. The second flank 6101 is curved; the mean inclination forms an angle of less than 30 with the tangent to the drive ring 61 so that when the tooth 4 is in contact with the second flank 6101, it can slide along this second flank 6101 without driving same, and without driving the drive ring 61 either.

[0075] The drive ring 61 further comprises an external toothing 611 exhibiting teeth 6110 the tips of which are concentric with the drive ring 61, the hollow 6111 between each of the teeth 6110 being designed to accept the end 620 of a positioning jumper 62.

[0076] The jumper 62 thus collaborates with the external toothing 611 in order to center the hour indications in the window 10 (FIG. 2). The end 620 of this jumper 62 opposes the movement of the drive ring 61 by engaging in the hollow 6111 between the teeth 6110 of the external toothing of the drive ring 61. The stiffness of the jumper 62 is chosen such that the jumper 62 holds the drive ring 61 in place when it is not being driven by the tooth 4 and so as to allow the end of the jumper 620 to disengage from the hollow 6111 of the external toothing 611 connected to the jumping display ring 60 under the action of the tooth 4 and by virtue of a rack spring 33.

[0077] The jumper 62 has a first end (or output end) and a second end (or input end). The two ends exhibit a non-zero inclination with respect to the vertical walls of the external toothing 611 of the drive ring 61. The jumper 62 collaborates with a jumper spring 63.

[0078] In another embodiment, only the first end of the jumper has a non-zero inclination in relation to the hollows of the external toothing of the drive ring 61; the second end is therefore appreciably parallel to the edges of these hollows when the jumper thus modified is engaged in the hollow. This particular shape of jumper allows clockwise rotation of the drive ring 61 to be blocked. In other words, the second end of the jumper is configured in such a way as to block clockwise rotation of the drive ring 61 and thus avoid a display error in the event of an impact for example.

[0079] The operation of the mechanism during normal moving-on of the retrograde display 5, namely as the minute hand 2 progressively advances from 0 to 60 minutes, will now be described with the aid of FIGS. 2 to 6.

[0080] FIG. 2 illustrates the mechanism just after the return of the retrograde minute hand 2, which therefore points toward the minute 0. In this position, the first end of the rack 31 is resting against the smallest diameter of the snail cam 5. The retrograde mobile 20 is engaged with the internal toothing 320 in the opening of the rack. In the example illustrated, the tooth 4 is not in contact with the internal toothing 610 of the jumping display ring 60.

[0081] FIG. 3 corresponds to a position of the minute hand 2 at minute 17. The snail cam 5, driven in the counterclockwise direction by the teeth of the friction disk center wheel 9 (FIG. 1), causes the second end of the rack in the figure to move in the clockwise direction to move the minute hand 2 in the clockwise direction along the minutes scale 11. The drive member 4 (tooth) presses against the tip of a tooth of the internal toothing of the drive ring 61 without having engaged with it. The drive ring 61 and the jumping display ring 60 therefore remain immobile, their position being fixed by the positioning jumper 62 which is collaborating with the hollows 6111 on the external periphery of the drive ring 61 (FIG. 1).

[0082] FIG. 4 corresponds to a position of the minute hand 2 at minute 35. The retrograde mobile 20 continues to turn in the clockwise direction and the minute hand 2 to move in the clockwise direction along the minutes scale 11. The drive member 4 (tooth) comes into contact with an oblique flank 6101 of the internal toothing 610 of the drive ring 61 (FIG. 1) without having engaged with it. The drive ring 61 and the jumping display ring 60 therefore remain immobile.

[0083] FIG. 5 corresponds to a position of the minute hand 2 at minute 59. The first end of the rack 31 is in contact with the snail cam 5 near to the maximum-diameter portion 51 thereof. The drive member 4 (tooth) comes into contact with a tip of the internal toothing 610. During the course of the interval from 0 to 59 minutes, the tooth 4 slides along the toothing of the drive ring 61 (FIG. 1), without interfering with the position thereof.

[0084] FIG. 6 corresponds to a position of the minute hand 2 at minute 60. The first end of the rack 31 is situated at the peak of the cam 5. The drive member 4 (tooth) has moved beyond the tip of the internal toothing 610 and has engaged with a first flank 6100 of the internal toothing 610 of the drive ring 61 (FIG. 1). This ring is still held in place by the positioning jumper 62.

[0085] At minute 60, the falling of the rack 3 against the snail cam 5 simultaneously causes the near-instantaneous return of the minutes indicator 2 to 0 in the counterclockwise direction and a jump of the drive ring 61 (FIG. 1) likewise in the counterclockwise direction. This return is illustrated in FIGS. 6 to 11.

[0086] FIGS. 6 and 7 illustrate the start of the return to minute 0 of the retrograde indicator and the start of the jump of the jumping display. The first end of the rack 31 begins its fall from the peak of the snail cam 5. The second end of the rack 32 rotates in the counterclockwise direction causing the retrograde indicator positioned at minute 55 and the tooth 4 to rotate in the same direction. The drive ring 61 is therefore driven in the counterclockwise direction by the tooth 4, by virtue of the rack spring 33 which progressively relaxes. As it relaxes, the rack spring 33 (FIG. 1) transmits to the jumping display ring 60 (FIG. 1) enough energy to cause the end 620 of the positioning jumper 62 to leave the hollow 6111 of the external toothing 611. The movement of the jumping display ring 60 in the counterclockwise direction, causing the time to move on from h to h+1, can be seen through the window 10.

[0087] FIGS. 8 and 9 illustrate the next part of the return of the retrograde indicator. The retrograde indicator is positioned at minutes 40 and 25 respectively. The tooth 4 moves along the first flank of the internal toothing 610. The movement of the jumping display ring 60 in the counterclockwise direction, into a position between two jumping display elements 6, can be seen through the window 10. The end 620 of the positioning jumper 62 moves along the tooth 6110.

[0088] FIG. 10 illustrates the end of the return of the retrograde indicator. The retrograde indicator is positioned at minute 17 and the tooth 4 is almost at the tip of the internal toothing 610 connected with the jumping display ring 60, and will soon no longer be in mesh with the internal toothing 610. The new jumping display element 6 can be seen through the window 10. The positioning jumper 62 (not depicted) has dropped back into a hollow 6111 of the external toothing 611.

[0089] FIG. 11 illustrates the return of the retrograde indicator to minute 0. The retrograde indicator is positioned at minute 0 and the tooth 4 is no longer in contact with the internal toothing 610 connected to the jumping display ring 60. The first end of the rack lies on the smallest-diameter part of the cam 5. The new position of the jumping display element 6 can be seen through the window 10.

[0090] In the embodiment illustrated, the minutes are displayed by the position of the retrograde indicator 2 on a minutes scale (not depicted). The minutes scale covers a circular arc of less than 360 but greater than 180, for example of 240. The window in which the current hour is displayed lies facing the opening portion of the scale, at the 6 o'clock position in the example illustrated.

[0091] In the embodiment illustrated by the figures described hereinabove, the mechanism allows retrograde display of the minutes and jumping display of the hours. Such a mechanism may, however, be used for the jumping display of information other than the hour, and/or for the retrograde display of information other than the minutes.

REFERENCE NUMERALS USED IN THE FIGURES

[0092] 1 Mechanism for a watch movement [0093] 2 Retrograde indicator [0094] 20 Retrograde mobile [0095] 200 Toothing of mobile 20 [0096] 3 Rack [0097] 31 First end of the rack [0098] 32 Second end of the rack [0099] 320 Toothing of the rack 3 [0100] 33 Rack spring [0101] 4 Drive member/tooth [0102] 41 Axis [0103] 42 Spring [0104] 5 Cam [0105] 51 Peak of the cam [0106] 52 Release drive wheel [0107] 6 Jumping display element [0108] 60 Jumping display ring, for example hours ring. [0109] 61 Drive ring connected to jumping display ring [0110] 610 Internal toothing of drive ring 61 [0111] 6100 First flank of toothing 610 [0112] 6101 Second flank of toothing 610 [0113] 6102 Tip of toothing 610 [0114] 611 External toothing of drive ring 61 [0115] 6110 Tooth of toothing 611 [0116] 6111 Hollow of toothing 611 [0117] 62 Jumper for positioning the drive ring 61 [0118] 620 End of positioning jumper 62 [0119] 9 Center wheel friction disk/retrograde minutes intermediate transfer gear [0120] 10 Jumping hours window [0121] 11 Minutes scale