Timepiece mechanism comprising a jumping disc

A timepiece mechanism comprising:

• a jumping disc configured to jump by one step in a first direction of rotation;
• a driving device configured to drive the jumping disc, the driving device comprising a rotary drive member configured to be, with the jumping disc, stationary during a rest phase, and, during a jump phase, to drive the jumping disc by one step in a jumping manner in said first direction of rotation;
• and
• a locking device configured to lock the jumping disc, the locking device being configured to allow a rotation of the jumping disc in said first direction of rotation during the jump phase and to prevent the rotation of the jumping disc at least in said first direction of rotation during the rest phase, said locking device comprising a locking lever mounted between the jumping disc and the drive member, the locking lever comprising a head, said locking lever being configured to move between a high locking position in which said head is held by an outer circumferential edge of the drive member while being able to form a rotation stop in said first direction of rotation for the jumping disc during the rest phase, and a low release position in which said head is engaged in a notch provided on said outer circumferential edge of the drive member to be disengaged from the jumping disc, said notch being configured to be at least partially positioned facing the head of the locking lever at the a start of the jump phase so that the jumping disc is free to rotate, and to no longer be facing said head one one of after the jump phase, and (ii) before an end of the jump phase, so that the locking lever returns to the high locking position.