Abstract: A control device (2) mounted in an opening (20) in a middle (16) and including a support (14) and a rotatable part, which has a shaft (12), a gripping member (4) and a control member (6) forming a rotation sensor (26). The sensor includes a magnetic detector provided inside the watch case in a radial peripheral region of the control member. On a first side of a circular opening (22), the support has a cavity (24) which is open in the axial direction. The cavity is configured to house the control member fixedly mounted on the shaft, such that this control member can be momentarily retracted, at least for the most part, into the cavity following an axial movement of the shaft into a position in which the magnetic detector is mounted inside the watch case.

Abstract: The invention relates to a thermocompensated mechanical resonator including a strip whose core, which is of polygonal section, includes single crystal silicon. According to the invention, one or a number of faces of the core has a coating for making the resonator less sensitive to temperature variations. The invention concerns the field of timepieces.