Backlash take-up wheel

1. A backlash take-up timepiece wheel, for meshing with mobile component toothing formed of external teeth of a given width arranged consecutively with a constant pitch on a pitch circle of an opposing mobile component, said backlash take-up wheel comprising:

a backlash take-up wheel toothing arranged on a pitch circle of the backlash take-up wheel to mesh with said mobile component toothing, the backlash take-up wheel toothing including a series of identical pairs of teeth arranged consecutively with a constant backlash take-up wheel pitch on said pitch circle of the backlash take-up wheel, each pair including, on either side of a first radial axis, a first flexible tooth and a second flexible tooth, wherein the pitch thereof varies between two successive teeth, between a smaller pitch which is smaller than a theoretical pitch for meshing with a given opposing mobile component, and a larger pitch which is larger than said theoretic pitch, the total of said smaller pitch and said larger pitch being equal to two times said theoretical pitch, and wherein each first flexible tooth is placed on a first flexible arm and each second flexible tooth is placed on a second flexible arm, said first flexible arm and said second flexible arm being attached to a hub of said backlash take-up wheel, wherein a first distance is measured on said pitch circle of the backlash take-up wheel between said first flexible tooth and said second tooth of the same said pair, and a second distance is measured on said pitch circle of the backlash take-up wheel between one first tooth and one second tooth of the backlash take-up wheel toothing which are adjacent but appertain to different consecutive pairs of the series of identical pairs of teeth, and wherein said first distance is different from said second distance.

2. The backlash take-up wheel according to claim 1 , wherein, to allow use in either direction of pivoting, each pair in the series of identical pairs of teeth is symmetrical to the first radial axis of said pair and wherein said first flexible tooth is a mirror of said second flexible tooth.

3. The backlash take-up wheel according to claim 1 , wherein each first flexible tooth and each second flexible tooth includes, on either side of a second radial axis, two lateral stop surfaces respectively facing towards said two second adjacent teeth and towards said two first adjacent teeth, and that, in an unrestrained state, a third distance between two of said lateral stop surfaces facing two of said consecutive teeth is constant.

4. The backlash take-up wheel according to claim 1 , wherein each first flexible tooth has a rigid head, attached to an axial hub of said backlash take-up wheel by the first flexible arm.

5. The backlash take-up wheel according to claim 1 , wherein each second flexible tooth has a rigid head, attached to an axial hub of said backlash take-up wheel by the second flexible arm.

6. The backlash take-up wheel according to claim 1 , wherein said first teeth and second teeth overhang relative to an axial hub with a radial projection of between 0.50 and 0.95 times the value of a maximum radius of said backlash take-up wheel.

7. The backlash take-up wheel according to claim 1 , wherein the wheel is symmetrical to a plane passing through the pivot axis thereof and through one said radial axis of one said pair comprised therein.

8. A timepiece gear train comprising at least a first backlash take-up wheel according to claim 1 , and at least one mobile component comprising one of said mobile component toothing formed of said external teeth of said given width arranged consecutively with the constant pitch on the pitch circle of the mobile component, wherein, in any meshing position of said first backlash take-up wheel and of said mobile component, at least one external tooth of the mobile component is clamped by one first tooth and one second tooth of one pair in the series of identical pairs of teeth of the backlash take-up wheel, the one first tooth and the one second tooth separated from each other, in an unrestrained state, by said first distance.

9. The gear train according to claim 8 , wherein, according to angular meshing positions of said first backlash take-up wheel and of said mobile component, either a single external tooth of the mobile component is clamped by a single pair in the series of identical pairs of teeth of the backlash take-up wheel, or two external teeth of the mobile component, separated by a third external tooth of the mobile component, are clamped by two successive pairs in the series of identical pairs of teeth of the backlash take-up wheel.

10. The gear train according to claim 8 , wherein, over one complete revolution of said mobile component, only one out of two of said external teeth is in drive contact with one of said first and second flexible teeth of said backlash take-up wheel toothing of said first backlash take-up wheel.

11. The gear train according to claim 8 , wherein said mobile component toothing of said mobile component has rigid external teeth.

12. The gear train according to claim 8 , wherein said mobile component toothing includes said external teeth which are each symmetrical to a radial axis passing through a pivot axis of said mobile component, and said mobile component is symmetrical to a plane passing through the pivot axis thereof and through a radial axis of one external tooth of said mobile component toothing.

13. The gear train according to claim 8 wherein, in the unrestrained state, the first distance measured on said pitch circle of the backlash take-up wheel between said first flexible tooth and said flexible second tooth of the same said pair is the smallest distance between two successive flexible teeth and, and is substantially smaller than said given width, measured on said pitch circle of the mobile component, of said external teeth forming said mobile component toothing.

14. The gear train according to claim 13 , wherein, in the unrestrained state, the second distance, measured on said pitch circle of the backlash take-up wheel between one first flexible tooth and one second flexible tooth of the backlash take-up wheel toothing which are adjacent but appertain to different pairs of the series of identical pairs of teeth, is the greatest distance between two successive first and second flexible teeth and is substantially smaller than a sum of said constant pitch of said mobile component toothing and said given width, measured on said pitch circle of the mobile component, of said external teeth forming said mobile component toothing.

15. A timepiece movement comprising at least one gear train according to claim 8 , wherein said mobile component drives and said first backlash take-up wheel is driven, and wherein said at least one gear train is reversible and behaves identically in both directions of pivoting.