Mechanism for a watch movement

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, the rack and the retrograde mobile being arranged in such a way as to rotate in the same direction, wherein the mechanism further comprises:

a jumping display ring to display a second item of time information, said jumping display ring comprising an internal toothing, and

said rack comprising a drive member collaborating, with said internal toothing to drive said jumping display ring in rotation in a jumping way.

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 , 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.

4. The mechanism as claimed in claim 1 , said drive member being mounted on the rack by means of an axis allowing it to pivot.

5. The mechanism as claimed in claim 4 , comprising a spring mounted on said rack and applying force to press said drive member against said internal toothing.

6. The mechanism as claimed in claim 1 , in which said first item of time information is the current hour, and said second item of time information is the current minute.

7. A method for displaying items of time information by means of a watch movement as claimed in claim 6 , 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.

8. The method as claimed in claim 7 , in which said jumping display ring is driven in rotation in a jumping way by a drive member mounted on said rack.

9. The method as claimed in claim 7 , 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.

10. The method as claimed in claim 7 , 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.

11. The method as claimed in claim 7 , 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.

12. The method as claimed in claim 7 , 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.