The regularity of operation of an escapement mechanism is conditional upon the proper control of maintenance of oscillations and particularly of the impulse, whose intensity may be irregular in a watch whose barrel torque varies.
The search for optimum operating security is a constant preoccupation of designers of timepiece movements.
FR Patent Application No 2928015A1 in the name of LENOBLE discloses a tangential impulse escapement device with a pallet lever for a watch, including a toothed escape wheel, a pallet lever and at least one sprung balance. The pallet lever is in two parts each pivoting on a distinct axis, the two parts are hinged to each other via two transmission arms terminating at their adjacent ends in a common hinge, so that the two parts of the pallet lever rotate at the same speed but in opposite directions. Each part of the pallet lever includes a locking pallet-stone and an impulse pallet-stone, the latter receiving impulses from the escape wheel teeth in a tangential manner. This escapement device includes two sprung balances with distinct axes of oscillatory rotation, and each part of the pallet lever comprises a fork engage able in driving mesh on an impulse pin of the corresponding sprung balance.
Patent Application No WO 2011/064682 A1 in the name of FERRARA concerns a pallet lever in two parts hinged to each other, the hinge including an eccentric cam integral with the part of the pallet lever carrying the horns and guard pin, and cooperating with a fork integral with the part of the pallet lever carrying the pallet-stones.
Patent Application No EP2444 860A1 in the name of AUDEMARS PIGUET RENAUD ET PAPI discloses a pallet lever which includes two parts, each pivoting about an axis, and hinged to each other, the pivoting of one of the parts causing the other to pivot with higher amplitude.
Patent No EP2105806 in the name of GIRARD PERREGAUX discloses an escapement mechanism arranged to transmits impulses from a drive source to an oscillating regulator such as a sprung balance, via a strip spring which works by buckling about an inflection point. This strip spring is capable of accumulating energy from the drive source between two impulses and transmitting it to the oscillating regulator on each impulse via first and second levers. To optimise adjustment of the tension of the strip spring, the spring is mounted on a frame which is deformable symmetrically relative to a first axis passing through the axes of rotation of the regulator, of the first and second levers, and through the inflection point, and relative to a second axis perpendicular to the first axis and passing through the ends of the strip spring.