Patent ID: 12242229

DETAILED DESCRIPTION OF THE INVENTION

The invention relates to the field of horology, and more particularly that of musical boxes or timepieces comprising a musical or striking mechanism. The invention will more specifically be described for the preferred application of a timepiece comprising a striking mechanism. Nevertheless, the invention is applicable to the regulation of any wheel set for generating music or striking wheel set. In this regard, it will be designated in the remainder of the disclosure under the generic term “timepiece” a timepiece or a musical box, and under the term “striking mechanism” a musical or striking mechanism.

In this description of a preferred use of the invention illustrated inFIGS.1to3, the invention relates to a striking mechanism1comprising a striking wheel set4governor2, for a timepiece (not shown in the figures for reasons of clarity). The timepiece is typically a striking mechanical watch, such as for example a repeater watch. In this preferred use of the invention illustrated inFIGS.1to3, the striking wheel set4is a percussion hammer that is configured to come to strike on a gong5of the striking mechanism1. Alternatively not shown, the wheel set may be one or more lever(s), or also one or more pin(s) in movement that come to strike on the blades of a pin-barrel in the case of a musical watch. Alternatively also, the gong5may be replaced with one or more resonator(s), gong(s), or bell(s), or also with a resonance box in the case of a musical box.

As seen inFIG.3, the striking mechanism1comprises, apart from the governor2, an energy source6delivering a mechanical torque, and means for transmitting mechanical torque from the energy source6to the striking wheel set4(said latter not being shown in the figures for reasons of clarity). Preferably, the striking mechanism1also comprises at least one electrical component10connected to the governor2. In the particular embodiment illustrated inFIGS.1and2, the mechanism1comprises three electrical energy storage components10, namely ceramic condensers. The energy stored in said condensers may for example be reused by luminous components within the timepiece in order to carry out a synchronised illumination. Alternatively or additionally, the electrical component(s)10may be an accumulator, and/or a luminous component, such as a light-emitting diode, and/or an electrical component for generating sound or vibrations within the mechanism1. When the electrical component10is an electrical component for generating sound, said latter is for example a loudspeaker associated with an amplifier.

In the particular embodiment illustrated inFIGS.1to3, the energy source6is a striking barrel received in a location12of the mechanism1(the striking barrel6not being shown inFIGS.1and2for reasons of clarity). The striking barrel6is typically a spring barrel, which may be wound in a single movement by a user of the timepiece. Such a spring barrel delivers in general a mechanical torque that varies according to the unwinding of the spring. Alternatively not shown, the energy source6may be a barrel of the mechanical horological movement of the timepiece, whereof a portion of the energy accumulated is recovered for the musical or striking mechanism1.

The wheel set4governor2or regulator is intended to regulate the tempo of the striking, or of the melody according to the case, of the mechanism1. In the particular embodiment illustrated inFIGS.1to3, the wheel set4governor2is intended to regulate the tempo of the striking of the striking mechanism1. More specifically, the governor2is configured to regulate, around a reference speed value, the pivoting speed of the wheel set4about a pivot axis. For this, the governor2comprises means14for braking the wheel set4(that will be described subsequently) configured to return the pivoting speed of the wheel set4to the reference speed.

As seen inFIG.3, the governor2consists of a system comprising an electric generator16and an electronic circuit18for regulating the rotation speed of the generator16. The generator16is for example connected to the electronic circuit18via a rectifier circuit19.

As illustrated inFIG.3, the electric generator16comprises a rotor20and a stator22. The rotor20is connected to the energy source6delivering the mechanical torque, via a kinematic chain not seen in the figures (gear train). The stator22for example consists of an assembly of coils24connected in series (a single coil24being shown inFIG.3for reasons of clarity). The coils24are advantageously non-iron coils, which makes it possible to prevent any start positioning torque. Preferably, the electric generator16is an electro-dynamic microgenerator. When the mechanism1comprises one or more electrical component(s)10, said latter may be directly or indirectly connected to the electric generator. When one of the components10at least is an electrical energy storage component, the electrical energy accumulated in said component may in particular be used to supply the electronic circuit18when the energy source6does not deliver mechanical torque.

Preferably, the electronic circuit18is an oscillator circuit. In the particular embodiment illustrated inFIGS.1to3, the electronic circuit18comprises an integrated servo-control circuit26with complementary metal oxide semiconductor (CMOS) technology. According to this particular embodiment, and as illustrated inFIG.3, the electronic circuit18also comprises a time base, such as a quartz28or a MEMS resonator or an RLC oscillating circuit, which is connected to the integrated circuit26and which provides a reference frequency. Alternatively not shown, the electronic circuit18comprises a capacitance inductance resistance circuit configured to provide a reference frequency.

The integrated circuit26has an input terminal29connected to the assembly of coils24of the generator16and making it possible to recover an analogue signal31coming from said latter. Without this being limiting within the scope of the present invention, the integrated circuit26comprises for example a chain of divisions (including an inhibition programming logic), an hysteresis comparator for logically forming the analogue signal31, a reversible counter, as well as a decision logic (such elements not being shown inFIG.3for reasons of clarity). The integrated circuit also comprises a transistor30, typically an insulated gate field effect and metal oxide semiconductor (MOS) transistor.

The hysteresis comparator is connected to the input terminal29. The chain of divisions is connected between the quartz28and a positive input of the reversible counter. The other input of the reversible counter, which is a negative input, is connected to the output of the hysteresis comparator. The decision logic is connected as output of the reversible counter, and has an output for controlling the transistor30.

The reversible counter carries out the difference between the two pulsed type signals coming from the quartz28on the one hand, and from the generator16on the other hand, as well as the integration of pulses over time. The reversible counter further indicates the advance or the delay of the angular position of the rotor20of the generator16in relation to the ideal angular position thereof (given by the quartz28) and the decision logic that monitors the counter decides on the instruction to be established. Said decision logic in fact acts according to the value of the reversible counter (positive or negative) and controls the transistor30.

The transistor30is connected to the stator22of the electric generator16. More specifically, as illustrated inFIG.3, the transistor30is connected in parallel at the same time as the coils24via the two drain and source electrodes thereof. The transistor30constitutes the braking means14, which are braking means configured to electrically brake the rotation of the rotor20of the generator16.

The electronic circuit18is thus configured to regulate, around a reference speed, the rotation speed of the generator16, and to thus brake the wheel set4so as to regulate the pivoting speed thereof about the pivot axis. The reference speed is for example equal to 7 revolutions per second, without this being limiting within the scope of the present invention. Thus, regardless of the mechanical torque delivered by the energy source6, the electric generator16rotates at a constant or near-constant speed. For this, the frequency of the signal coming from the generator16(which is proportional to the rotation speed of said latter) is compared to a sub-multiple of the reference frequency (provided by the quartz28in the embodiment inFIG.3). If necessary, the generator16is then electrically braked by the braking means14that constitutes the transistor30, so as to be controlled at the reference frequency provided by the quartz28. For this, the transistor30, which is controlled by the decision logic of the integrated circuit26, short-circuits the assembly of coils24of the stator22for a fraction of the period of the alternating voltage provided by the generator16. The transistor30then acts as a means for intermittent and pulsed braking of the rotor20of the generator16.

During operation, when the rotor20of the generator16is moved when exposed to a torque provided by the spring of the barrel6, an induced alternating voltage appears at the terminals of the assembly of coils24of the stator22. The induced alternating voltage is then used for two functions: firstly said voltage is rectified via the rectifier circuit19and makes it possible to supply the integrated circuit26, and secondly said voltage makes it possible to provide an electrical energy source available for the timepiece. Said rechargeable electrical energy source then makes it possible, for example, to supply the electrical component(s)10. The electrical energy accumulated may subsequently be advantageously reused by an electrical component, such as a light-emitting diode in order to illuminate elements of the timepiece, such as gongs, hammers or hands for example, or also by a component for generating sound or vibrations within the mechanism.