System for driving and holding in position a mobile unit for displaying time or time derivative information

A system for driving and holding in position a mobile unit for displaying time or time derivative information, comprising:

• a driving device for driving the mobile unit, the driving device comprising a driving cam and a driving lever provided to drive a driving member,
• a device for holding the mobile unit in position,
• a device for activating and deactivating the position-holding device comprising a deactivation cam, and
• a device for mechanically coupling or synchronizing the driving cam and the deactivation cam, wherein the mechanical coupling or synchronizing is one-to-one so that, in each driving phase actuated by the driving cam, at a time when the driving cam causes the driving member to drive the mobile unit, the device for mechanically coupling or synchronizing causes the deactivation cam to hold the position-holding device in a deactivated state.