A microsystem for setting the rate of a timepiece oscillator, including a wheel/inertia block including an off-centre 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 balance spring for a watch resonator mechanism, the balance spring (100) including a flexible strip (2) wound on itself in a plurality of coils, the strip (2) having a predefined stiffness, the balance spring (100) including means for adjusting its stiffness, including a flexible element (5) arranged in series with the strip (2), the flexible element (5) connecting one end (4) of the strip (2) to a fixed mount (38), so as to add additional stiffness to the continuation of the strip (2), the flexible element (5) preferably having a stiffness greater than that of the strip (2), the flexible element (5) including two flexible parts (15, 16) each connecting the strip (2) to the fixed mount (38), the two flexible parts (15, 16) being arranged relative to each other with axial symmetry along an axis (A) preferably passing substantially through the centre (0) of the balance spring.

A balance spring for a watch resonator mechanism, the balance spring (100) including a flexible strip (2) wound on itself in a plurality of coils, the strip (2) having a predefined stiffness, the balance spring (100) including means for adjusting its stiffness, including a flexible element (5) arranged in series with the strip (2), the flexible element (5) connecting one end (4) of the strip (2) to a fixed mount (38), so as to add additional stiffness to the continuation of the strip (2), the flexible element (5) preferably having a stiffness greater than that of the strip (2), the flexible element (5) including two flexible parts (15, 16) each connecting the strip (2) to the fixed mount (38), the two flexible parts (15, 16) being arranged relative to each other with axial symmetry along an axis (A) preferably passing substantially through the centre (0) of the balance spring.

A spiral spring for a watch resonator mechanism, including a flexible strip (2) wound on itself and having a predefined stiffness and including an arrangement for adjusting its stiffness, including a flexible element (5) arranged in series with the strip, the flexible element (5) connecting one end (4) of the strip to a rigid support (11), to add additional stiffness to the strip (2). The flexible element (5) preferably having a stiffness greater than that of the strip (2). A prestressing device (6) applies a variable force or torque to the flexible element to vary its stiffness, and includes a lever (14) connected to the flexible element and actuatable to transmit the force or the torque to the flexible element, the lever (14) having an end (15) movable in a first direction (D1). A retaining device (25) prevents movement of the lever (14) substantially in a second direction (D2).

A spiral spring for a watch resonator mechanism, including a flexible strip (2) wound on itself and having a predefined stiffness and including an arrangement for adjusting its stiffness, including a flexible element (5) arranged in series with the strip, the flexible element (5) connecting one end (4) of the strip to a rigid support (11), to add additional stiffness to the strip (2). The flexible element (5) preferably having a stiffness greater than that of the strip (2). A prestressing device (6) applies a variable force or torque to the flexible element to vary its stiffness, and includes a lever (14) connected to the flexible element and actuatable to transmit the force or the torque to the flexible element, the lever (14) having an end (15) movable in a first direction (D1). A retaining device (25) prevents movement of the lever (14) substantially in a second direction (D2).

The watch movement includes a mechanical resonator with a balance and a spring, a device for setting the oscillation frequency of the mechanical resonator and a device for setting the guide mark on the mechanical resonator. A moving part of the setting device includes a fastener for attaching an outer end part of the spring and a device for defining the active length of the spring. A mechanism for varying the active length of the spring includes a first toothed wheel, carried by the moving part, and a first toothing, arranged along the outer end part of the spring, with which the first toothed wheel meshes. The fastener holds the outer end part by friction such that the first toothed wheel can drive this outer end part via the first toothing and thus vary the active length of the spring.

The watch movement includes a mechanical resonator with a balance and a spring, a device for setting the oscillation frequency of the mechanical resonator and a device for setting the guide mark on the mechanical resonator. A moving part of the setting device includes a fastener for attaching an outer end part of the spring and a device for defining the active length of the spring. A mechanism for varying the active length of the spring includes a first toothed wheel, carried by the moving part, and a first toothing, arranged along the outer end part of the spring, with which the first toothed wheel meshes. The fastener holds the outer end part by friction such that the first toothed wheel can drive this outer end part via the first toothing and thus vary the active length of the spring.

A return member for a balance wheel of a timepiece, replacing a spiral spring. This return member includes a rake provided with a toothed sector arranged to work together with a balance wheel pinion. The rake has an axis of rotation allowing it to move between two extreme positions, called working positions, separated by a rest position. The return member also has two springs arranged to press the rake towards its rest position. Each spring is made up of an elastic blade arranged to store energy, then to return it to the rake. Each elastic blade works alternately so that they never work simultaneously. The return member may be in an escapement, a clockwork movement or a timepiece comprising such a movement.

A return member for a balance wheel of a timepiece, replacing a spiral spring. This return member includes a rake provided with a toothed sector arranged to work together with a balance wheel pinion. The rake has an axis of rotation allowing it to move between two extreme positions, called working positions, separated by a rest position. The return member also has two springs arranged to press the rake towards its rest position. Each spring is made up of an elastic blade arranged to store energy, then to return it to the rake. Each elastic blade works alternately so that they never work simultaneously. The return member may be in an escapement, a clockwork movement or a timepiece comprising such a movement.