Mechanism to avoid rate variations due to gravitation in a sprung balance regulating organ, and timepiece provided with such a mechanism

Mechanism avoiding the rate variations due to the effect of gravitation on a regulating organ (2, 3) in a clockwork movement of a timepiece where the regulating organ comprises a sprung balance (2) and an escape wheel (3) mounted onto a platform (4), said platform (4) including a counterweight and being mounted so as to freely rotate about at least a first axis (A-A) relative to a plate (1) of the movement so that this platform (4) may rotate about said first axis (A-A) under the effect of terrestrial gravitation;

• characterized in that the mechanism comprises a wheelwork including a driving kinematical chain (M) linking the escape wheel (3) to a barrel system (10) of the timepiece, as well as a corrective kinematical chain (C) compensating the movements and speed of the platform (4) relative to the plate (1), so that these movements of the platform (4) will not perturb the chronometry of the timepiece, this wheelwork including one or several trains of epicycloidal gears, and each of said trains in said wheelwork containing wheels with straight toothing exclusively.