Horology calendar system

1. A horology calendar system comprising:

a date display member comprising an opening; and

a month display member arranged so as to display an indication of the month in the opening,

wherein the date display member rotates to display the current date of the month, and the month display member rotates to display the current month of the year,

wherein the horology calendar system further comprises a drive element for driving the month display member,

wherein the drive element comprises a kinematic connection element connecting the date display member to the month display member,

wherein the connection element comprises a Maltese cross.

2. The horology calendar system as claimed in claim 1 , comprising a drive element for driving the month display member arranged to drive the month display member while at least one of the month display member and the opening is not visible to the user.

3. The horology calendar system as claimed in claim 2 , wherein the drive element comprises a date wheel provided with at least one tooth meshing with several teeth of a month wheel.

4. The horology calendar system as claimed in claim 2 , wherein the drive element for driving the month display member is arranged to drive the month display member between the second and the thirtieth day of the month indicated by the calendar system.

5. The horology calendar system as claimed in claim 2 , wherein the drive element for driving the month display member is arranged to drive the month display member between the tenth and the twentieth day of the month indicated by the calendar system.

6. The horology calendar system as claimed in claim 2 , comprising a drive element for driving the month display member arranged to drive the month display member by one step while the date display member is driven by one step.

7. The horology calendar system as claimed in claim 1 , comprising a drive element for driving the month display member arranged to drive the month display member by one step while the date display member is driven by one step.

8. The horology calendar system as claimed in claim 1 , wherein the connection element is arranged to drive the month display member by at most 1/n of a step while the date display member is driven by one step, where n is a natural integer greater than 1.

9. The horology calendar system as claimed in claim 1 , wherein the Maltese cross is provided with projections collaborating with n teeth of a date wheel, the Maltese cross having a toothset meshing with n teeth of a month wheel or wherein the kinematic connection element comprises a device including one or more intermediate wheels meshing with the month cam and meshing with a date wheel.

10. The horology calendar system as claimed in claim 1 , wherein at least one of (i) the date display member and the month display member are pivoted about one and the same axis, and (ii) a date wheel and a month wheel are pivoted about one and the same axis.

11. The horology calendar system as claimed in claim 1 , wherein at least one of (i) the date display member is a date wheel and (ii) the month display member is a month wheel.

12. The horology calendar system as claimed in claim 1 , wherein at least one of the date display member and the month display member are disks or annular portions of disks.

13. The horology calendar system as claimed in claim 1 , wherein the horology calendar system comprises a dial equipped with an aperture for displaying the days of the month, in which aperture the opening is arranged to appear.

14. The horology calendar system as claimed in claim 1 , wherein the horology calendar system is of the instantaneous jump type.

15. The horology calendar system as claimed in claim 1 , wherein at least one tooth of a date wheel is arranged so as to allow an additional jump of the date display member at at least one of (i) the end of a month comprising fewer than thirty days and (ii) the end of a thirty-day month.

16. The horology calendar system as claimed in claim 1 , wherein a month wheel comprises a cam for programming an annual or perpetual calendar.

17. A horology movement comprising a system as claimed in claim 1 .

18. A timepiece comprising a system as claimed in claim 1 .

19. The horology calendar system as claimed in claim 1 , wherein the month display member is arranged so as to display the indication of the month in the opening when at least one of (i) the opening is visible to a user of the calendar system and (ii) the calendar system is indicating a given day of a given month.

20. The horology calendar system as claimed in claim 1 , wherein the month display member is arranged so as to display the indication of the month in the opening when the calendar system is indicating the first day of a given month.

21. A horology calendar system comprising:

a date display member comprising an opening; and

a month display member arranged so as to display an indication of the month in the opening,

wherein the date display member rotates to display the current date of the month, and the month display member rotates to display the current month of the year,

wherein the horology calendar system further comprises a drive element for driving the month display member arranged to drive the month display member while at least one of the month display member and the opening is not visible to the user,

wherein the drive element for driving the month display member is arranged to drive the month display member between the second and the thirtieth day of the month indicated by the calendar system.

22. The horology calendar system as claimed in claim 21 , wherein the drive element for driving the month display member is arranged to drive the month display member between the tenth and the twentieth day of the month indicated by the calendar system.

23. The horology calendar system as claimed in claim 21 , comprising a drive element for driving the month display member arranged to drive the month display member by one step while the date display member is driven by one step.