A bimetallic device, the difference in expansion coefficient of which is between 10 and 30 10.sup.−6 K.sup.−1, for providing a resonator with thermal compensation via the balance wheel.

A timepiece includes a mechanical oscillator, formed by a balance and a piezoelectric balance spring, and a control device for controlling the frequency of the mechanical oscillator. This control device is arranged to be capable of generating time-separated control pulses, each including a momentary decrease in an electrical resistance applied by the control device between two electrodes of the piezoelectric balance spring relative to a nominal electrical resistance. The control device is arranged to be capable of applying a plurality of control pulses during each time of a series of distinct correction times or without interruption in a continuous time window, in order to respectively synchronize the mechanical oscillator at a correction frequency whose value depends on a detected positive or negative temporal drift or at a desired frequency for the mechanical oscillator.

A regulating member (1) for a horological movement including an oscillating weight, for example a balance, and a balance spring including a flexible strip (2) wound about itself in a plurality of turns, the strip (2) having a predefined rigidity to allow the oscillating weight to undergo a rotary oscillatory motion, the strip (2) including an outer end (9), wherein the regulating member (1, 10) includes a temperature-compensating resilient device configured to adapt the stiffness thereof as a function of the temperature to compensate for the effect of temperature on the regulating member (1, 10), the resilient device including a resilient element (5) connecting the outer end (9) to a first support (7) that is stationary relative to the horological movement, as well as preloading means (6) for applying a variable force or torque to the resilient element (5) as a function of the temperature.

A process for producing a metal alloy balance wheel by molding, the process including the following steps: a) making a mold in the negative shape of the balance wheel, b) getting hold of a metal alloy that has a thermal expansion coefficient of less than 25 ppm/ C. and is able to be in an at least partly amorphous state when it is heated to a temperature between its glass transition temperature and its crystallization temperature, c) putting the metal alloy into the mold, the metal alloy being heated to a temperature between its glass transition temperature and its crystallization temperature so as to be hot-molded and to form a balance wheel, d) cooling the metal alloy to obtain a balance wheel made of the metal alloy, e) releasing the balance wheel obtained in step d) from its mold.

A governor includes a balance spring including a base member made of silicon, for example, and a balance wheel. The balance spring includes a coating film of DLC that is applied to a surface of the silicon base member to improve the strength of the balance spring. A spring constant of the balance spring changes in accordance with the temperature change. A moment of inertia of the balance wheel changes in accordance with the temperature change. A change in an oscillation period due to the temperature change is suppressed by the change in the spring constant of the balance spring and by the change in the moment of inertia of the balance wheel.

Some embodiments are directed to adjusting the oscillation frequency of an oscillating system for a watch movement, including: selecting a hairspring, selecting a balance belonging to a predetermined class, without a balance rim, at least two weight elements for balancing in a predetermined batch, pairing the hairspring with the balance and the at least two weight elements, measuring an oscillation frequency of the oscillating system including the hairspring, the balance and the at least two weight elements, and selecting at least one of a balance of another class or of the at least two weight elements of another batch if the measured oscillation frequency does not correspond to a desired oscillation frequency.

A balance for a regulating member of a horological movement, the balance including, at least in part, a body that can be deformed as a function of temperature, the deformable body being arranged, at least in part, on the periphery of the balance, the balance being configured so as to be able to move about a centre of rotation, the balance including a device for adjusting the sensitivity of the deformable body to temperature change, the adjustment device being provided with a first inertial element arranged on the deformable body in order to be able to modify the moment of inertia thereof, the first inertial element being capable of moving relative to the deformable body into a plurality of positions, wherein the positions form a continuous set. A horological movement and a regulating member can include such a balance.

A balance wheel including a rim connected to a hub with at least one arm, wherein the balance wheel includes an adjustable auxiliary temperature compensation system mounted in the space defined by the rim to allow adjustable temperature compensation of the balance wheel.

A governor includes a balance spring including a base member made of silicon, for example, and a balance wheel. The balance spring includes a coating film of DLC that is applied to a surface of the silicon base member to improve the strength of the balance spring. A spring constant of the balance spring changes in accordance with the temperature change. A moment of inertia of the balance wheel changes in accordance with the temperature change. A change in an oscillation period due to the temperature change is suppressed by the change in the spring constant of the balance spring and by the change in the moment of inertia of the balance wheel.

A balance spring, in particular for a horological regulating member, the balance spring (100) including a flexible strip (2) wound about itself in several turns, the strip (2) having a predefined stiffness, the balance spring (100) having a stiffener for adjusting its stiffness, the balance spring (1) also including an actuator (10) for actuating the adjustment means, depending on the ambient temperature. Also, a horological regulating member including such a balance spring.