An assembly for the removable attachment of a balance spring of a horological movement including a balance bridge, the assembly including the balance spring, a means of retaining the balance spring, and a removable locking part. The balance spring includes a coil winding which extends between a first free end of an inner first coil and a second free end of an outer last coil, the second free end including an attachment means in which the retaining means is engaged to ensure the removable attachment of the balance spring by its outer last coil. The attachment means is dimensioned so that, in a rest position, the balance spring is not in contact with the retaining means engaged in this attachment means, the locking part for the removable attachment of the second free end being engaged on the retaining means to lock the attachment means.

A microsystem for setting the rate of a timepiece oscillator, including a wheel/inertia block including an off-center unbalance and a toothing and arranged to pivot with respect to a base plate of the microsystem, which includes an actuator driving a first active click arranged to drive the toothing, and includes a device for stopping the toothing in position, wherein the actuator is a thermomechanical actuator arranged to convert a flow of light energy into a displacement of a distal end of the thermomechanical actuator, which carries a first active click or directly controls a movement of a first active click, and the microsystem is capable of incorporation in a watch including a crystal transparent to predetermined wavelengths ranges and allowing the passage of a light ray to regulate the microsystem.

A method adjusting oscillation frequency of a sprung balance assembly formed at random from balance springs and balance wheels. A production mechanism is set to limit a sample standard deviation of a single batch of balance springs to a predetermined maximum value, and to limit a sample standard deviation of a single batch of balance wheels to a predetermined maximum value within a given unbalance tolerance. The mean of the balance population is classified according to the mean of the balance springs, to obtain a difference corresponding to a maximum inertia decrease value of the balances, between extreme gaussian distribution values of balances and of balance springs. A random balance spring sample is taken from the single batch of balance springs and a random balance from among the single batch of balances. The inertia of the balance is adjusted according to a torque value of the balance spring sample.

A method of improving pivoting of a wheel set for a scientific instrument, including an arbor pivoting or oscillating about an axis, in which: static balancing of the wheel set is performed to bring the center of gravity onto the axis; a desired value is determined for resulting unbalance moment of the wheel set about the axis, corresponding to a predetermined divergence between a first principal longitudinal axis of inertia of the wheel set, and the axis; at a predetermined speed about the axis, the resulting unbalance moment is measured with regard to the axis; and an adjustment of the resulting unbalance moment is made within a given determined tolerance with regard to the desired value, and performed by machining both sides of a median plane including the two secondary axes of inertia of the wheel set.

A timepiece sub-assembly includes, irreversibly fixed to a main plate and each irreversibly pre-adjusted by the irreversible securing of adjustment and/or assembly components, after the particular timepiece function thereof has been adjusted and function checked on the test bench, functional modules including a gear train module, a display module, and a time-setting module. Other mechanical sub-assemblies, each irreversibly fixed to the preceding lower order mechanical sub-assembly, include various modules including motor module, frame-mounted self-winding device module, escapement holder regulating module, motion work train, date module, and self-winding module. A mechanical movement including at least one mechanical sub-assembly of this type and a watch including a mechanical movement of this type are also disclosed. A method of assembling mechanical sub-assemblies of this type by the irreversible securing of mechanical sub-assemblies and irreversibly pre-adjusted modules is also disclosed.

An inertial mass (1) intended to be mounted on a regulating organ (10), particularly of a horological movement, the inertial mass being configured to be subjected to a rotary oscillation movement at a predetermined frequency, the inertial mass including a rigid main body (2), characterised in that it comprises a flexible inertial element (3) assembled with the main body (2), the flexible inertial element (3) being configured to modify the geometry of the inertial mass (1) according to the oscillation amplitude. Also, a regulating organ and a horological movement comprising such an inertial mass.

Balance with inertia adjustment for timepieces, including a hub defining the pivot axis of the balance, a rim, a web extending between a lower plane and an upper plane on either side of a median plane, the web including at least one arm connecting the rim to the hub, the arm including a housing configured to receive and hold in place at least one inertia block. According to the invention, the inertia block has a front face and a rear face and is integrated in the balance arm, so that the front face and rear face are substantially in the upper plane and the lower plane.

A device for detecting and synchronizing a position of at least one first wheel of a timepiece mechanism for an electronic analog wristwatch, includes this first wheel extending in a plane. The detection and synchronization device includes at least one light source emitting a light beam and at least one light detection system. A first light-reflecting element projects from one of an upper or lower surfaces of the first wheel of the timepiece mechanism. The light source and the light detection system are arranged so that in a determined position of the first wheel of the timepiece mechanism, the light beam emitted by the light source is reflected by the first light-reflecting element in the direction of the light detection system. The detection and synchronization device is housed within a case of the wristwatch.

A method for adapting a timepiece movement includes measuring a loss of energy for each free oscillation of the balance at atmospheric pressure; measuring the loss of energy for each free oscillation at a given low pressure corresponding to a working pressure intended for a modified movement; using i) the measured loss of energy at atmospheric pressure and ii) the measured loss of energy at the given low pressure, determining a percentage of energy gain of the balance between respective i) measurements of the measured loss of energy at atmospheric pressure and ii) measurements of the measured loss of energy at the given low pressure; and reducing a torque delivered to the escapement by a value corresponding to the determined percentage of energy gain.

A timepiece assembly including a first component and a second component assembled under stress, wherein at least one part of the surface of the assembly is coated with a protective layer intended to cover defects such as cracks or incipient cracks after assembly. It also relates to the method for manufacturing this assembly.