Mechanical stop and start system for a function, and watch comprising such a system
A mechanical stop and start system for a function of a timepiece, including a mass, mounted so as to be able to move on a frame, between a first and a second end position, which are defined respectively by a first stop and a second stop. The mass portion moves in a bistable manner, under the effect of gravity, tensioning a spring between the first and second end positions, and relaxing the spring between the second and first end positions.
1. Mechanical system for stopping and starting a function of a timepiece, comprising a mass, movably mounted on a frame between a first and a second extreme position, defined respectively by a first and a second stop, said mass being displaced, under the effect of gravity, thereby loading of a spring between the first and second extreme positions, and thereby relaxing said spring between the second and first extreme positions,
said mass being kinematically or directly connected to a control member for said function,
the mass and a force of the spring being determined as a function of the force required to command said function and displace the control member, and of predetermined spatial orientations of the frame, in which the mass is bi-stably displaced from one to the other of its extreme positions, according to a resultant of the forces exerted by the spring and by gravity, the displacement of the mass from the first extreme position to the second extreme position being able to start said function via the control member, and the displacement of the mass from the second extreme position to the first extreme position being able to stop said function via the control member.
2. System according to claim 1 , wherein the mass is mounted movably in rotation and is unbalanced.
3. System according to claim 1 , wherein the mass is connected to a speed regulator.
4. System according to claim 3 , wherein the speed regulator is an escapement, an inertia brake, or a viscous-friction device in a bath.
5. System according to claim 1 , comprising a device for blocking the mass.
6. System according to claim 1 , wherein the control member bears a magnet.
7. System according to claim 1 , wherein the spring is calculated such that orientations of the frame triggering respectively the starting and stopping of the function, are different.
8. System according to claim 1 , wherein elements that implement said function are mounted on the frame.
9. Watch having a system according to claim 1 and a mechanism that implements said function, wherein said mass is transferred from its first extreme position to its second extreme position, and from its second extreme position to its first extreme position, when the watch is brought respectively into a first spatial orientation or a second spatial orientation.
10. Watch according to claim 9 , wherein the first and the second spatial orientation are similar.
11. Watch according to claim 9 , wherein the first and the second spatial orientation are different.
12. Watch according to claim 11 , wherein, in the first orientation, the watch has an angle alpha of between 3° and 35°, Beta=0°, Gamma=0° and, in the second orientation, the watch has an angle alpha of between 15 and 18°, Beta=0°, Gamma=0°,
the angle alpha being the angle of rotation of the watch about an axis passing through the positions 9 H and 3 H of a dial, alpha being equal to 0 when the dial is horizontal, the angle beta being the angle of rotation about the axis 12 H- 6 H, and the axis gamma being the angle of rotation about the orthogonal axis passing through a center of the dial.
13. Watch according to claim 9 , wherein the system comprises a device for blocking the mass which is accessible from a outside of the watch.
14. Watch according to claim 9 , wherein the mechanism is chosen from among a chronograph mechanism, a striking mechanism, a visual animation mechanism.