Timepiece assembly comprising a mechanical oscillator associated with an electronic device for controlling its mean frequency

A timepiece provided with a mechanical movement comprising:

• a mechanism for indicating at least one time data item,
• a mechanical resonator capable of oscillating around a neutral position corresponding to its state of minimum potential energy, and
• a device for maintaining the oscillation of the mechanical resonator forming with said mechanical resonator a mechanical oscillator which is arranged to pace the running of the indicator mechanism;
• the timepiece being also provided with a control device arranged to control the mean frequency of the mechanical oscillator and which includes:
• a sensor arranged to be capable of detecting a number of periods or vibrations in the oscillation of the mechanical resonator in a useful operating range of the mechanical oscillator,
• an auxiliary oscillator,
• a braking device which is arranged to be capable of momentarily applying a braking force to the mechanical resonator,
• a control circuit including a measuring device arranged to be capable of measuring, on the basis of a detection signal provided by the sensor, a temporal drift of the mechanical oscillator relative to the auxiliary oscillator, this control circuit being arranged to determine whether a measured temporal drift corresponds to at least a certain gain or to at least a certain loss and if so, to be capable of generating a control signal which selectively activates the braking device as a function of the measured temporal drift in order to generate at least one braking pulse which is applied to the mechanical resonator to at least partially correct the measured temporal drift;
• wherein the control circuit includes a device for generating at least a frequency Fsup which is arranged to be capable of generating a periodic digital signal at this frequency Fsup;
• and wherein, when the control circuit determines a temporal drift corresponding to at least a certain loss in the operation of the timepiece, the control circuit is arranged to be capable of momentarily providing to the braking device a first control signal to activate said braking device such that the braking device generates, during a first correction period, a series of periodic braking pulses which are applied to the mechanical resonator at said frequency Fsup;
• this frequency Fsup and the duration of the first correction period being provided and the braking device being arranged so that the series of periodic braking pulses at frequency Fsup is capable to generate, in the first correction period, a synchronous phase in which the mechanical oscillator is synchronized to a correction frequency which is greater than a set point frequency F0c provided for the mechanical oscillator.