A balance for a horological movement, including rigid parts constituted by a hub defining the pivot axis of the balance, at least one felloe sector, at least one arm connecting the at least one felloe sector to said hub, and including a slot for receiving and gripping in position an inertia-block, the slot opening into a housing delimited on the one hand by a rigid part of the balance, and on the other hand an elastic arm including a first end integral with a rigid part of the balance, and a second free distal end. The elastic arm can have a body of a non-constant section, a part of the body having a greater thickness than the rest of the elastic arm so as to have a larger volume of material under stress and store a maximum of elastic energy.

A balance for a horological movement, including rigid parts constituted by a hub defining the pivot axis of the balance, at least one felloe sector, at least one arm connecting the at least one felloe sector to said hub, and including a slot for receiving and gripping in position an inertia-block, the slot opening into a housing delimited on the one hand by a rigid part of the balance, and on the other hand an elastic arm including a first end integral with a rigid part of the balance, and a second free distal end. The elastic arm can have a body of a non-constant section, a part of the body having a greater thickness than the rest of the elastic arm so as to have a larger volume of material under stress and store a maximum of elastic energy.

A balance-spring, particularly for a timepiece resonator mechanism. An adjustment device include a single elongated flexible element (5) arranged in series of strip (2), connecting one end (4, 9) of said strip (2) to a fixed support (11), to add an additional stiffness to the strip (2), and having a stiffness greater than that of the strip (2). A prestressing means (6) applies at least two different stresses on the elongated flexible element (5), the first stress being provided by a tensile/compressive force directed substantially in the longitudinal direction F.sub.L of the elongated flexible element (5), and the second stress being provided, either by a force directed substantially in a direction substantially orthogonal F.sub.T to the longitudinal direction of the elongated flexible element (5), or by a torque M, preferably a bending moment, in such a way as to vary the stiffness of the elongated flexible element (5).

A balance-spring, particularly for a timepiece resonator mechanism. An adjustment device include a single elongated flexible element (5) arranged in series of strip (2), connecting one end (4, 9) of said strip (2) to a fixed support (11), to add an additional stiffness to the strip (2), and having a stiffness greater than that of the strip (2). A prestressing means (6) applies at least two different stresses on the elongated flexible element (5), the first stress being provided by a tensile/compressive force directed substantially in the longitudinal direction F.sub.L of the elongated flexible element (5), and the second stress being provided, either by a force directed substantially in a direction substantially orthogonal F.sub.T to the longitudinal direction of the elongated flexible element (5), or by a torque M, preferably a bending moment, in such a way as to vary the stiffness of the elongated flexible element (5).

A device for autonomous adjustment of the active length of a balance spring includes a regulator mounted on a plate with a cock, a balance spring stud holder being pivotally mounted on the cock, the regulator being pivotally mounted on the stud holder and including a pivot arm and device for changing the active length of the balance spring by pivoting the regulator. The device includes an elastic stress device to exert an elastic, return-to-position action on the regulator, and an inertia block, mounted for free rotation on the cock and connected to the pivot arm of the regulator, arranged to move the pivot arm of the regulator between a rest position and a correction position of the device, and simultaneously act on the device for changing the active length of the balance spring.

A device for autonomous adjustment of the active length of a balance spring includes a regulator mounted on a plate with a cock, a balance spring stud holder being pivotally mounted on the cock, the regulator being pivotally mounted on the stud holder and including a pivot arm and device for changing the active length of the balance spring by pivoting the regulator. The device includes an elastic stress device to exert an elastic, return-to-position action on the regulator, and an inertia block, mounted for free rotation on the cock and connected to the pivot arm of the regulator, arranged to move the pivot arm of the regulator between a rest position and a correction position of the device, and simultaneously act on the device for changing the active length of the balance spring.

A timepiece rotating regulator mechanism for regulating the rotational speed of a mechanism subjected to the action of a motor device through a transmission device, including an oscillator mechanism indirectly connected to the transmission device by a movement transformation device including a connecting-rod-crank-handle system, with a crank-handle rotated about a crank-handle axis by the transmission device, and a connecting-rod angularly moveable on the one hand in relation to the crank-handle, and on the other hand in relation to an inertial mass that this oscillator mechanism includes, to ensure the maintenance of the oscillator mechanism by the energy supplied by the motor device, and to ensure the speed regulation of a train that the transmission device include in relation to the frequency of the oscillator mechanism.

A timepiece rotating regulator mechanism for regulating the rotational speed of a mechanism subjected to the action of a motor device through a transmission device, including an oscillator mechanism indirectly connected to the transmission device by a movement transformation device including a connecting-rod-crank-handle system, with a crank-handle rotated about a crank-handle axis by the transmission device, and a connecting-rod angularly moveable on the one hand in relation to the crank-handle, and on the other hand in relation to an inertial mass that this oscillator mechanism includes, to ensure the maintenance of the oscillator mechanism by the energy supplied by the motor device, and to ensure the speed regulation of a train that the transmission device include in relation to the frequency of the oscillator mechanism.

A rotating resonator mechanism (60) including a flexible guide (5) and an oscillating mass (2), the flexible guide (5) including two main flexible strips (4, 6) and a rigid portion (7). The flexible strips are joined to the rigid portion and the oscillating mass. An adjustment means adjusts the stiffness of the resonator mechanism, and includes a flexible element connected to the rigid portion and to a fixed support (11), so that the flexible guide (5) is suspended by the flexible element (12), the flexible guide (5) and the flexible element (12) extending substantially in the same plane so that the oscillating mass (2) performs a rotating movement about a virtual pivot. The adjustment means also includes pre-stressing means (15) to apply a variable force or torque on the flexible element (12) or the flexible guide (5), to vary the stiffness of the flexible element (12).

A balance of a timepiece including an adjustment face provided with at least one recess provided for receiving a projected material for an implementation of an adjustment of the rate of the timepiece notably by the modification of the inertia and of the unbalance of the balance, the recess including an opening and a back notably a solid back or a back fully or partially forming an orifice, the back being at most partially visible from a position defined above the opening notably on a central axis of the opening.