CH715399A2 - Timepiece comprising a mechanical oscillator associated with an electronic device for regulating its average frequency. - Google Patents

Abstract

The timepiece (2) is provided with a mechanical movement (4) which comprises a mechanical resonator (14), a sensor (24) detecting the oscillations of the mechanical resonator, and a braking device (26) arranged to generate braking pulses in response to a control signal (SF) supplied by a regulation circuit (22) associated with an auxiliary oscillator. The regulation circuit is arranged to be able to detect a time drift, negative or positive, in the oscillation of the mechanical resonator and to generate, in a correction period, in association with the braking device, when the time drift corresponds to at least a certain delay, a series of braking pulses which are applied to the mechanical resonator at a frequency F SUP in a given range of values and preferably greater than a frequency FZ (N) = 2⋅F0c / N, F0c being a frequency setpoint for the mechanical resonator and N a positive integer.

Description

Technical area

The present invention relates to a timepiece comprising a mechanical oscillator whose average frequency is synchronized with a set frequency determined by an auxiliary electronic oscillator. To this end, the timepiece includes a regulating device capable of correcting any time drift in the operation of the mechanical oscillator, which cadences the progress of the mechanical movement which incorporates it.

More particularly, the timepiece is provided with a mechanical movement which includes: a mechanism indicating at least one time datum, a mechanical resonator capable of oscillating around a neutral position corresponding to its state of minimum potential energy, and a mechanical resonator maintenance device forming with this mechanical resonator a mechanical oscillator which is arranged to clock the progress of the indicator mechanism.

This timepiece is further provided with a regulating device arranged to regulate the average frequency of the mechanical oscillator and comprising: a sensor to be able to detect a number of periods or of alternations 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 able to temporarily apply a braking force to the mechanical resonator, and a regulation circuit comprising a measuring device arranged to be able to measure, on the basis of a detection signal supplied by the sensor, a temporal drift of the mechanical oscillator relative to the auxiliary oscillator, this regulation circuit being arranged for determine if the measured time drift corresponds to at least a certain advance or at least a certain delay and to be able, if this is the case, to generate a control signal which selectively activates the braking device as a function of the measured time drift , so as to generate at least one braking pulse which is applied to the mechanical resonator to at least partially correct this time drift.

Technological background

Timepieces of the type defined above in the field of the invention have recently been disclosed in patent applications CH 713 306 A2 and EP 3 339 982 A1.

The timepiece disclosed in document CH 713 306 A2 comprises a mechanical movement, provided with a mechanical oscillator, and an electromagnetic system formed by at least one magnet mounted on the balance of a mechanical oscillator and d '' a coil carried by a pendulum support. The electromagnetic system is part of a regulating device designed to regulate the average frequency of the mechanical oscillator in the case where this oscillator has a positive time drift relative to an auxiliary oscillator, for example a quartz oscillator, as in the case where it has a negative time drift. After having observed that a braking pulse, applied to the resonator forming the mechanical oscillator in an alternation of its oscillation, generates a negative phase shift when it occurs before the resonator passes through its neutral position and a positive phase phase when it occurs after the resonator has passed through its neutral position, this document proposes a solution in which the time drift is measured and the oscillating movement of the resonator is observed so that the regulating device can selectively apply one or more braking pulses to it, respectively via one or more short-circuits of the coil, in one or more respective first half-vibrations (located before the resonator passes through its neutral position) when the measured time drift corresponds to at least a certain advance and in one or more seconds respective half-waves (located after the reson has passed by its neutral position) when the time drift corresponds to at least a certain delay. To do this, the electronic circuit of the regulating device includes a time counter or a timer making it possible to determine, on the basis of detections of pulses of induced voltage in the coil, whether an induced voltage pulse occurs in a first half-wave or in a second half-wave so as to be able to selectively apply the braking pulses as indicated above. The regulation process implemented in this document, although remarkable, requires a relatively complex electronic circuit which therefore consumes a certain electrical energy which is taken from the mechanical oscillator, which tends to reduce its amplitude of oscillation and therefore the duration of normal operation for a certain mechanical energy stored in a barrel of mechanical movement.

The timepiece disclosed in document EP 3 339 982 A1 is remarkable for the system designed to generate mechanical braking pulses applied to the balance of the mechanical oscillator. However, the regulatory process is similar to that of the previous document. There is a sensor arranged to be able to detect the passages of the resonator through its neutral position. On the basis of knowledge of the setpoint period for the mechanical oscillator and of the detections carried out by the sensor, a logic control circuit determines with the aid of a time counter the instants at which the braking pulses must be triggered for that they intervene selectively before or after the passage of the mechanical resonator through its neutral position in corresponding half-waves, that is to say to apply the mechanical braking pulses either in the first half-waves, or in the second two-half alternations. In this case too, a relatively complex electronic circuit is necessary.

Summary of the invention

The main object of the present invention is to simplify the electronic circuit of the device for regulating the average frequency of a mechanical oscillator, by providing an alternative to the regulating devices of the prior art, described in the background. technological plan, which is easy to implement in a timepiece.

To this end, the invention relates to a timepiece as defined above in the field of the invention and which is characterized in that the regulation circuit comprises a device generating at least one frequency which is arranged so as to be able to generate a periodic digital signal at a frequency FSUP; and by the fact that the regulation circuit is arranged to be able to supply, when it determines a time drift corresponding to at least a certain delay in the running of the timepiece, momentarily to the braking device a first control signal for activate this braking device so that the braking device generates, during a first correction period, a series of periodic braking pulses which are applied to the mechanical resonator at the frequency FSUP. This frequency FSUP and the duration of the first correction period are provided and the braking device is arranged so that the series of periodic braking pulses at the frequency FSUP can generate, during the first correction period, a synchronous phase in which the mechanical oscillator is synchronized to a correction frequency which is greater than a set frequency F0c provided for the mechanical oscillator.

In a main embodiment, the frequency FSUP is included in a first range of values extending between (M + 1) / M⋅ and (M + 2) / M, inclusive, multiplied by a frequency FZ (N ) equal to twice a set frequency F0c for the mechanical oscillator divided by a positive integer N, that is [(M + 1) / M] ⋅FZ (N) <FSUP = <[(M + 2) / M] ⋅FZ (N) with FZ (N) = 2⋅F0c / N, M being equal to a hundred times two with the power K with K equal to a positive whole number greater than zero and less than thirteen, that is to say 0 <K <13 and M = 100⋅2 <K>, and N being expected to be less than M divided by thirty, ie N <M / 30.

In the case where the regulation circuit determines a time drift corresponding to at least a certain advance in the running of the timepiece, two general embodiments are provided. In the first general embodiment, the regulation circuit is arranged to be able, after having detected said at least a certain advance, to stop the mechanical oscillator and then momentarily block the mechanical resonator so as to at least partially correct said at least one some advance detected.

In the second general embodiment, said device generating at least one frequency is a frequency generator device arranged so as to be able to further generate a periodic digital signal at a frequency FINF and the regulation circuit is arranged to be able to supply, when it determines a time drift corresponding to at least a certain advance in the running of the timepiece, momentarily to the braking device a second control signal to activate this braking device so that the braking device generates , during a second correction period, a series of periodic braking pulses which are applied to the mechanical resonator at the frequency FINF. This FINF frequency and the duration of the second correction period are provided and the braking device is arranged so that the series of periodic braking pulses at the FINF frequency can generate, during the second correction period, a synchronous phase in which the mechanical oscillator is synchronized to a correction frequency which is lower than the set frequency F0c.

The FINF frequency is advantageously included in a second range of values extending between (M-2) / M, inclusive, and (M-1) / M multiplied by the frequency FZ (N), ie [(M- 2) / MJ] ⋅FZ (N) = <FINF <[(M-1) / M] ⋅FZ (N).

In a main variant of the second general embodiment, the regulation circuit is arranged to be able to supply, each time the measurement circuit determines a time drift corresponds to at least a certain advance or at least a certain delay, momentarily at the braking device a control signal which is selectively formed by: a first periodic activation signal of the braking device, which is determined by said periodic digital signal at said frequency FINF, when the time drift corresponds to said at least a certain advance, so as to generate a first series of braking pulses which are applied to the mechanical resonator at the FINF frequency, and a second periodic activation signal of the braking device, which is determined by said periodic digital signal at said frequency FSUP, when the time drift corresponds to said at least a certain delay, so as to generate a second series of periodic braking pulses which are applied to the mechanical resonator at the frequency FSUP.

In particular, the braking pulses have a duration TP of less than a quarter of a setpoint period T0c, ie TP <T0c / 4, T0c being by definition the inverse of the setpoint frequency F0c.

In a preferred variant, the positive integer K is greater than two and less than ten, ie 2 <K <10, and the number N is less than the number M divided by one hundred (N <M / 100).

In a general variant, the regulation circuit is arranged so that the control signal is supplied to the braking device, each time this regulation circuit determines that the time drift corresponds to said at least a certain advance or to said audit. at least a certain delay, during a correction period during which the frequency of the mechanical oscillator is synchronized respectively with a first correction frequency Fcor1 which is in said second range of values calculated with FZ (N = 2) = F0c or on a second correction frequency Fcor2 which is in said first range of values calculated with FZ (N = 2) = F0c.

In a preferred variant, the duration of the synchronous phase is expected to be much greater than a maximum duration of a transient phase generally occurring at the start of the correction periods before the synchronous phase.

Brief description of the figures

The invention will be described below in more detail with the aid of the appended drawings, given by way of non-limiting examples, in which: <tb> Fig. 1 <SEP> shows, partially schematically, a first embodiment of a timepiece according to the invention; <tb> Fig. 2 <SEP> shows the diagram of the electronic circuit of a variant of the regulation device of the first embodiment; <tb> Fig. 3 <SEP> is a flow diagram of an operating mode of the regulation device of FIG. 2 implemented in its logic control circuit; <tb> Fig. 4 <SEP> gives, for a first mode of regulation according to the invention implemented in the first embodiment of the invention and in the case of a timepiece whose mechanism indicating a time datum presents in advance, graphs representing the time evolution of the angular position of the mechanical resonator, a first series of braking pulses applied to this mechanical resonator, in a correction period, as a function of a time drift also shown, as well as a graph of the evolution of the instantaneous frequency of the mechanical oscillator in a time zone encompassing the correction period considered; <tb> Fig. 5 <SEP> gives, for the first mode of regulation and in the case of a timepiece whose mechanism indicating a temporal datum exhibits delay, graphs representing the temporal evolution of the angular position of the mechanical resonator , a second series of braking pulses applied to this mechanical resonator, in a correction period, as a function of a time drift also shown, as well as a graph of the evolution of the instantaneous frequency of the mechanical oscillator in a time zone encompassing the correction period considered; <tb> Fig. 6 <SEP> shows, partially schematically, a second embodiment of a timepiece according to the invention; <tb> Fig. 7 <SEP> shows the mechanical resonator and an electromagnetic braking device forming the regulation device of the second embodiment; <tb> Fig. 8 <SEP> shows the diagram of the electronic circuit of a variant of the regulation device of the second embodiment; and <tb> Fig. 9 <SEP> gives, in the context of the second embodiment, the graphs of the angular position of the mechanical resonator over an oscillation period, of the voltage induced in a coil of the electromagnetic braking device and of a time interval distinct during which a short circuit is applied to the coil, in a stable regime of synchronization between a frequency generator of the regulating device and the oscillating mechanical resonator which is obtained during a series of braking pulses applied to the mechanical resonator.

Detailed description of the invention

In fig. 1 shows a timepiece according to the present invention. Apart from the arrangement of the regulation circuit and the operating mode of this control circuit, which implements a regulation method according to the present invention, this timepiece essentially corresponds to the first embodiment of the timepiece. described in document EP 3 339 982 with the aid of FIGS. 1 and 2 of this document, so that reference will be made to the teaching of this document and that all the variant embodiments will not be described here.

The timepiece 2 comprises a mechanical watch movement 4 which incorporates a mechanism 6 arranged to indicate at least one time datum, a mechanical resonator 14, formed by a balance 16 pivotally mounted on the plate 5 and a hairspring 18, and a device for servicing the mechanical resonator forming with this mechanical resonator a mechanical oscillator which cadences the operation of the mechanism indicating a time datum. The maintenance device comprises an exhaust 12, formed by an anchor and an escape wheel which is kinematically connected to the barrel 8 via the gear train 10. The mechanical resonator is capable of oscillating along an axis d oscillation, here a circular geometric axis, around a neutral position corresponding to a state of minimum mechanical potential energy. Each oscillation of the mechanical resonator defines an oscillation period and two half-waves.

The timepiece 2 further comprises a device for regulating the average frequency of the mechanical oscillator, this regulating device 20 comprising an electronic regulating circuit 22 which is associated with a reference time base constituted by a auxiliary oscillator 36. This auxiliary oscillator is formed by a quartz resonator 23 and a clock circuit 38 which maintains the quartz resonator and receives from the latter a reference frequency signal that this clock circuit outputs as form of a digital periodic reference signal Sq. It will be noted that other types of auxiliary oscillators can be provided, in particular an oscillator integrated entirely in the regulation circuit. By definition, the auxiliary oscillator is more precise than the mechanical oscillator. The regulating device 20 also includes a sensor 24 for detecting at least one angular position of the pendulum when it oscillates, making it possible to detect, for a useful operating range of the mechanical oscillator, a number of alternations or periods in l oscillation of the mechanical resonator. The regulation device also comprises a mechanical braking device 26 arranged to be able to apply momentarily a braking force to the mechanical resonator 14, in particular mechanical braking pulses to its balance wheel. Finally, the timepiece assembly includes an energy source 32 associated with a device 34 for storing the electrical energy generated by the energy source. The energy source is for example formed by a photovoltaic cell or by a thermoelectric element, these examples being in no way limiting. In the case of a battery, the energy source and the storage device together form a single electrical component.

Generally, the regulating device 20 also includes a measuring device arranged to measure, on the basis of position signals supplied by the sensor, a time drift DT of the mechanical oscillator relative to the auxiliary oscillator (base reference time 36). It is understood that such a measurement is easy when a sensor is provided capable of detecting the passage of the mechanical resonator through a certain angular position, in particular by its neutral position. Such an event takes place in all the half-oscillations of the mechanical oscillator. The measurement circuit will be described in more detail below.

The sensor 24 is arranged to be able to detect the passage of at least one reference point of the balance 16 through a certain given angular position relative to a support of this mechanical resonator. In an advantageous variant, the sensor is arranged to detect the passage of the mechanical resonator through its neutral position. It will be noted that, in this variant, the sensor can be associated with the anchor of the escapement so as to detect the tilting of this anchor during the oscillation maintenance pulses which are provided substantially when the mechanical resonator passes through its neutral position.

In a particular variant, the sensor 24 is an optical sensor, of the photoelectric type, which comprises a light source, arranged so as to be able to send a beam of light towards the pendulum, and a light detector, arranged to receive in return a light signal whose intensity varies periodically depending on the position of the pendulum. For example, the beam is sent to the lateral surface 15 of the serge 17, this surface having a limited area with a reflectivity different from the two neighboring areas, so that the sensor can detect the passage of this limited area and provide the device with regulates a position signal when this event occurs. It will be understood that the circular surface having a variable reflection for the light beam can be located in other places of the pendulum. The variation can in a particular case be produced by a hole in the reflecting surface. The sensor can also detect the passage of a certain part of the balance, for example an arm, the neutral position corresponding for example to the middle of a signal reflected by this arm. It is therefore understood that the modulation of the light signal makes it possible to detect in various ways at least one angular position of the pendulum, by a negative or positive variation of the light received. In other variants, the position sensor may be of the capacitive type or of the inductive type and thus be arranged so as to be able to detect a variation in capacitance, respectively of inductance as a function of the position of the balance. The sensor includes means for converting the analog light signal into a digital signal Se, It can also include a rocker which makes it possible to divide by two the frequency of the light signal when it intervenes once in alternation, so that the signal Se corresponds to the FO oscillation frequency of the mechanical oscillator. A person skilled in the art knows many sensors which can easily be incorporated into the watchmaking assembly according to the invention.

The mechanical braking device 26 is arranged to be able to apply to the balance 16 mechanical braking pulses so as to regulate the frequency of the mechanical oscillator when a certain time drift DT of this mechanical oscillator is observed. In an advantageous variant, a braking torque applied to the mechanical resonator by any mechanical braking pulse is provided for less than a blocking torque of the mechanical oscillator and the duration of the braking pulses is provided so as to take a certain maximum energy to the mechanical resonator so that the amplitude of the oscillation remains greater than a given minimum value. In other words, the braking torque is expected to be less than the torque exerted by the hairspring at the minimum amplitude provided and the duration of the pulses is such that this minimum amplitude is respected for a predefined minimum force torque which is exerted by the barrel (note that the mechanical oscillator is maintained by the barrel via the exhaust), this in order not to momentarily block the oscillation movement of the mechanical resonator during the braking pulses and to keep the mechanical oscillator within its range useful operation as soon as the barrel exerts a torque greater than the minimum torque provided. In another more general variant, it is possible to apply a braking torque greater than the torque exerted by the hairspring at the minimum amplitude provided, but the duration of the pulses is determined, taking into account the maintenance of the mechanical oscillator, so that this minimum amplitude is maintained for the minimum force torque of the barrel from which it is expected that the timepiece is functional and for any angular position of the mechanical resonator during the application of a braking pulse. It will be noted that the energy taken from the mechanical resonator is maximum when the braking pulse occurs during the passage of this resonator through its neutral position.

In fig. 1, the mechanical braking device is formed by an actuator 26 which comprises a mechanical braking member 28 arranged to be actuated, in response to a control signal SF supplied by the regulation circuit to the control circuit 30 of this actuator, so exerting, during the braking pulses, a mechanical braking torque on a braking surface 15 of the pivoting balance 16. In the variant shown, the braking surface is circular and defined by the external lateral surface of the clamp 17 of the balance. The mechanical braking member 28 comprises a movable part (defined by the free end of this member) which defines a braking pad arranged so as to be able to exert a certain pressure against the circular braking surface during the application of the braking pulses at the mechanical resonator.

The actuator 26 comprises a piezoelectric element supplied by a control circuit 30 which applies an electrical activation voltage to it as a function of the control signal SF supplied by the regulation circuit 22. When the piezoelectric element is momentarily set under tension, the braking member comes into contact with a braking surface of the balance wheel to brake it. In the example shown in fig. 1, the blade forming the braking member bends and its end part presses against the circular lateral surface 15 of the clamp 17 of the pendulum 16. The end part of the blade therefore defines a movable braking shoe. In a preferred variant, the pivoting balance and the mechanical braking member are arranged so that the braking pulses can be applied mainly by dynamic dry friction between the mechanical braking member and the braking surface 15. In another alternatively, a viscous friction can be provided between the braking member and a braking part of the pendulum.

In a particular variant (not shown), the balance comprises a central shaft which defines or which carries a part other than the balance of the balance defining a circular braking surface. In this case, a shoe of the braking member is arranged so as to come to exert pressure against this circular braking surface during the application of the mechanical braking pulses.

A circular braking surface, for an oscillating member which is pivoted (pendulum), associated with at least one brake shoe, carried by the braking device of the regulation device, constitutes a mechanical braking system which has advantages determinants. Indeed, thanks to such a system, braking pulses can be applied to the mechanical resonator at any time of the oscillations, and this independently of the oscillation amplitude of the balance. It will also be noted that the pad of the braking member can also have a circular contact surface, of the same radius as the braking surface, but a flat surface has the advantage of leaving a certain margin in the positioning of the braking relative to the balance wheel, which allows greater tolerances for manufacturing and mounting the braking device in the watch movement or at its periphery.

Advantageously, the various elements of the regulating device 20 form a module independent of the watch movement. Thus, this module can be assembled or associated with the mechanical movement 4 only when they are mounted, in particular in a watch case. In particular, such a module can be fixed to a casing circle which surrounds the watch movement. It is understood that the electronic regulation module can therefore be advantageously associated with the watch movement once the latter is fully assembled and adjusted, the assembly and disassembly of this module can intervene without having to intervene on the mechanical movement itself.

Generally, the regulation circuit 22 is arranged to be able to determine whether a time drift, which is measured by the measuring device on the basis of the signals it receives from the sensor 24 and from the reference time base 36, corresponds to at least a certain advance or at least a certain delay and in order to be able, if this is the case, to generate a control signal which selectively activates the braking device, to generate periodic braking pulses which are applied to the mechanical resonator with a braking frequency which is a function of the measured time drift, so as to at least partially correct this measured time drift.

In a main variant, the regulating circuit 22 comprises a frequency generator device arranged so as to be able to generate a first periodic digital signal SFI at a first frequency FINF (first braking frequency) and a second periodic digital signal SFs at a second frequency FSUP (second braking frequency).

The first FINF frequency is included in a range of values between (M-2) / M, inclusive, and (M-1) / M multiplied by a frequency FZ (N) which is equal to twice a setpoint frequency F0c, for the mechanical oscillator, divided by a positive integer N, ie FZ (N) = 2⋅F0c / N and [(M-2) / M] ⋅FZ (N) = <FINF < [(M-1) / M] ⋅FZ (N), M being a hundred times two to the power K with K equal to a positive integer greater than zero and less than thirteen, ie 0 <K <13 and M = 100 2 <K>, and N being expected to be less than M divided by thirty, ie N <M / 30. The second frequency FSUP is included in a range of values extending between (M + 1) / M and (M + 2) / M, inclusive, multiplied by the frequency FZ (N), with M and N as defined above. before, either [(M + 1) / M] ⋅FZ (N) <FSUP = <[(M + 2) / M] ⋅FZ (N). The operator "= <" means "equal to or less than", the limit being in the range of values.

The regulation circuit 22 is arranged to provide, each time it determines that the time drift DT of the mechanical oscillator corresponds at least to a certain advance or at least to a certain delay, momentarily to the braking device 26 a control signal SF during a correction period, this control signal SF being selectively formed by: the first periodic digital signal SFI when the time drift corresponds at least to the certain advance, so as to generate a first series of braking pulses 60 which are applied to the mechanical resonator 14 with a first trigger frequency F1d equal to the first frequency FINF (first braking frequency), and the second periodic digital signal SFS when the time drift corresponds to at least the certain delay, so as to generate a second series of braking pulses 61 which are applied to the mechanical resonator with a second trigger frequency F2d equal to the second frequency FSUP (second braking frequency).

In a preferred variant, the positive integer K is greater than two and less than ten, ie 2 <K <10 and the number N is less than the number M divided by one hundred (N <M / 100).

The braking pulses have a duration TP less than half of a set period T0c, ie TP <T0c / 2, T0c being by definition the inverse of the set frequency F0c for the mechanical oscillator formed by the resonator 14 and the exhaust 12. Preferably, in this first embodiment, the braking pulses have a duration TP less than a quarter of the setpoint period T0c, ie TP <T0c / 4.

[0037] FIG. 2 shows in detail the regulation circuit 22 and the control circuit 30 of the actuator 26 forming the mechanical braking device characterizing the first embodiment. The regulation circuit includes: two stages DIV1 and DIV2 of a frequency divider which receives at the input of the reference time base 36 the digital periodic reference signal SQet which supplies as an output a clock signal Sh at a lower frequency, a bidirectional differential counter CB which receives at one input the clock signal Sh and at a second input the digital signal Se from the sensor 24, which provides via this digital signal Se a digital pulse at each alternation or at each period of the oscillation of the mechanical resonator 14, and which outputs a measurement signal SD corresponding to a value representative of the time drift DT of the oscillator, a control logic circuit 40 which receives as input only the measurement signal SD (apart from a timing signal at a frequency generally much higher than that of the quartz oscillator, ie much higher than the frequency of the reference signal SQ) and which outputs, as a function of the value of the measurement signal SD, selectively a control signal Sr and a control signal Sa (which will be described later on in the description of a first regulation mode according to the invention with reference to Figs. 3 to 5), a first frequency generator 42 providing, when activated by the control signal Sa, momentarily the first periodic digital signal SFI and a second frequency generator 44 providing, when activated by the control signal Sr, momentarily the second SFS periodic digital signal, the first and second frequency generators together forming the frequency generator device mentioned above, and an OR logic gate which is connected as an input to the respective outputs of the two frequency generators 42 and 44 and which supplies the control signal SF as an output.

If the digital signal Se supplied by the sensor 24 has a period corresponding to an alternation of the mechanical oscillator, a flip-flop can be arranged in the regulation circuit 22 upstream of the counter CB so as to halve the pulses of the signal Se and supply a single pulse at the input of the counter CB per oscillation period T0.

The control circuit 30 of the braking device comprises a supply voltage source Vact which supplies the braking member to activate it via a switch 50, which is controlled by a periodic signal SP supplied by a timer 48 incorporated in the control circuit to manage the duration of the braking pulses. The timer selectively receives, via the control signal SF, the first periodic digital signal SFI and the second periodic digital signal SFS which activate it periodically during a correction period as a function of a detection of a certain advance or a certain delay. in the operation of the mechanical oscillator and therefore in the operation of the timepiece, and this in a repetitive manner during distinct and successive correction periods when a temporal drift persists. Thus, the timer 48 makes the switch 50 periodically conductive during each correction period to generate, as the case may be, either a first series of braking pulses 60 or a second series of braking pulses 61 (see FIG. 4 and 5).

In a preferred variant, the braking surface of the balance wheel 16 is configured so as to allow the braking device to start, within a useful operating range of the mechanical oscillator, a braking pulse from each first series of braking pulses and one braking pulse from each second series of braking pulses at any angular position of the mechanical resonator 14 between the two extreme angular positions which it can occupy when it oscillates within the useful operating range of the timepiece. As the amplitude of oscillation of the balance spring is generally greater than 180 ° (+/– 1800) in a conventional mechanical movement, the aforementioned condition implies, in the variant shown in fig. 1, that the lateral surface 15 of the balance wheel is circular and substantially continuous over the entire periphery of the balance wheel, so that the movable braking member 28 can press against the circular lateral surface substantially at all points.

[0041] FIG. 3 gives the flowchart of a first regulation mode implemented in the regulation circuit 22 of the first embodiment. After the circuit is activated at the start of its power supply or as part of an initialization during this activation, the counter CB is reset to zero and it begins to recognize any difference between the first number of pulses included in the signal Se received from the sensor 24 and the second number of pulses included in the clock signal Sh. The divider DIV1 & DIV2 is arranged so that the clock signal provides a setpoint signal with a number of pulses per time unit corresponding to the number of pulses provided in the signal Se per time unit for correct running of the timepiece, that is to say without time drift.

In each sequence of the first regulation mode, the logic circuit 40 firstly determines whether the value of the counter CB is greater than a positive integer N1H (corresponding to an advance of the mechanical oscillator) or less than a negative integer - N2H (corresponding to a delay of the mechanical oscillator). If CB> N1H (first case considered), the logic circuit activates the frequency generator 42 via a control signal Sa and this frequency generator begins to supply the first periodic digital signal SFI, at the first frequency FINF defined previously, to the circuit of control 30 of the braking device via logic gate 46. It follows that the braking device then begins to generate a first series of braking pulses 60 periodically at the first frequency FINF. Such a situation is shown in fig. 4 which shows: in the upper graph 54B, the angular position 8 of the mechanical resonator 14 over a plurality of oscillation periods during which a first series of braking pulses 60 occurs, in the intermediate graph 56A, the corresponding evolution of the frequency of the mechanical oscillator (the setpoint frequency F0c is equal to 4 Hz in the example treated, ie F0c = 4 Hz), and in the lower graph 58A, the corresponding evolution of the time drift DT of the mechanical oscillator.

Note that, to have a visible representation of the angular position of the mechanical resonator and the braking pulses, FIG. 4 shows in fact only a truncated series of braking pulses with a much smaller number of pulses than in reality, so that the time drift DT corresponds here to a fraction 81 h of the time drift N1H. But this makes it possible to clearly explain the operating principle. In the first case, in the example given, the natural frequency F0 = 4,0005 Hz, which corresponds to an advance of about ten seconds per day. When the time drift reaches or exceeds a value ε1H, namely in reality a value N1H, the braking device is actuated via the frequency generator 42 and it begins to periodically apply braking pulses 60 to the mechanical resonator at a frequency FINF defined previously. (for the sake of clarity of the drawing, all the pulses are shown in FIG. 4 as they occur during a stable / synchronous phase explained below). It will be noted that, in the example given, the braking pulses intervene in each period of oscillation and therefore with a frequency F0c, so that the frequency FZ (N) = 2⋅F0c / N, which is used to define the ranges for braking frequencies, is provided with N = 2. For example, as shown in fig. 4, the first FINF braking frequency is equal to 0.99975-F0c = 3.9990 Hz, i.e. FINF = FZ (2) - (L-1) / L = F0c- (L-1) / L with L = 4 ́000. This first FINF frequency is in the range [(M-2) / M] FZ (2) to [(M-1) / M] ⋅FZ (2) with K = 6, ie M = 100⋅2 <6>.

During the activation phase of the frequency generator 42, the logic circuit 40 waits for the value of the counter CB to become equal to or less than an integer N1H, which is less than the number N1h and preferably less in absolute value than N1h. In the example shown in fig. 4, N1H is equal to zero so that the fraction S1l of the time drift N1H given in this fig. 4 is also zero. As soon as the logic circuit has detected the expected event, either when the value of the counter CB becomes equal to or less than an integer N1H, the logic circuit terminates the activation of the generator 42 so that the latter is deactivated, which ends a correction sequence / correction period. If the value N1H = 4 and the counter CB counts the alternations of the mechanical oscillator, this corresponds to a time drift of half a second. In the example given, the duration DPC of a correction period is worth at least the above-mentioned number L multiplied by the time drift DT corrected, ie DPC = L⋅DT = 4000–0.5 = 2000 seconds. Thus, the correction periods each last approximately 34 minutes, including the initial transitional phase.

In fig. 4, the graph 56A of the frequency of the mechanical oscillator, formed by the mechanical resonator 14 and the escapement 12, shows the evolution of this frequency resulting from a sequence of the first regulation mode in the first case described below. before. While the frequency of the mechanical oscillator is greater than the setpoint frequency F0c in the absence of braking pulses, this frequency decreases as soon as a first series of braking pulses 60 occurs. A transient phase is observed before that the oscillation frequency stabilizes at a first correction frequency Fcor1 which is equal to the first frequency FINF with FZ (N = 2) = F0c, i.e. Fcor1 = FINF (N = 2), and therefore that a synchronous phase appears . Thus, during this synchronous phase, there is a synchronization of the mechanical oscillator on the first correction frequency Fcor1 which is slightly lower than the set frequency, which makes it possible to correct the time drift, as shown in the lower graph 58A of fig. 4. At the end of a sequence of the first regulation mode, the value of the time drift is reduced and is here equal to the whole number N1H which corresponds to a lower threshold for the time drift, while the whole number N1H, which generates the triggering of a first series of braking pulses, corresponds to an upper threshold of the time drift.

It will be noted that, in absolute values, the difference between FINF (N = 2) and F0c is preferably expected to be greater than a typical difference between FO and F0c. Thus, the braking device is generally activated less than half the time, or less than 12 hours per day. In the example given here, assuming that the natural frequency FO remains stable over time, the braking device will have to be applied for approximately 8 hours per day.

In each sequence of the regulation mode, if CB <- N2H (second case considered), the logic circuit 40 activates the frequency generator 44 via a control signal Sr and this frequency generator begins to supply the second digital signal periodic SFS, at the second frequency FSUPdefined above, to the control circuit 30 of the braking device via logic gate 46. As a result, the braking device then begins to generate a second series of braking pulses 61 periodically at the second FSUP frequency. Such a situation is shown in fig. 5 which shows: in the upper graph 54B, the angular position of the mechanical resonator 14 over a plurality of oscillation periods during which a second series of braking pulses 61 occurs, in the intermediate graph 56B, the corresponding evolution of the frequency of the mechanical oscillator, and in the lower graph 58B, the corresponding evolution of the time drift DT of the mechanical oscillator.

Note that, to have a visible representation of the angular position of the mechanical resonator and the braking pulses, FIG. 5, as in fig. 4, shows in fact only a truncated series of braking pulses with a much smaller number of pulses than in reality, so that the time drift DT corresponds here to a fraction -ε2H of the time drift -N2H. In the second case, in the example given, the natural frequency FO = 3.9995 Hz, which corresponds approximately to a delay of ten seconds per day. When the time drift reaches or becomes less than a value - ε2H, namely in reality a value -N2H, the braking device is actuated via the frequency generator 44 and it begins to periodically apply braking pulses 61 to the mechanical resonator. a frequency FSUP previously defined (for the sake of clarity of the drawing, all the pulses are shown in FIG. 5 as they occur during a stable / synchronous phase explained below). In the example shown, as in the first case, the frequency FZ (N) = 2⋅F0c / N is provided with N = 2, so that the frequency FZ (2) = F0c. The second FSUP braking frequency is equal to 1.00025⋅F0c = 4.001, or to FSUP = F0c⋅ (L + 1) / L with L = 4000. This second FSUPest frequency is in the range [(M + 1) / M] ⋅FZ (2) to [(M + 2) / M] ⋅FZ (2) with K = 6, ie M = 100–26. Note that there is no obligation to take the same value for N and the same value L in the second case (correction of a delay) as in the first case (correction of an advance).

During the activation phase of the frequency generator 44, the logic circuit 40 waits for the value of the counter CB to become equal to or greater than an integer N2L, which is greater than the number N2Het preferably less in absolute value than N2H . In the example shown in fig. 5, N2L is equal to zero, like N1L, so that the fraction £ 2l of the time drift N2L given in this fig. 5 is also zero. As soon as the logic circuit has detected the expected event, ie when the value of the counter CB becomes equal to or greater than the integer number N2L, the logic circuit terminates the activation of the generator 44 so that the latter is deactivated, this which ends a correction sequence. The correction sequence is provided in a loop, so that the logic circuit 40 then returns to the start of a next sequence and it waits for the detection of a new time drift. Each correction sequence corresponds to a correction period.

In fig. 5, graph 56B of the frequency of the mechanical oscillator shows the evolution of this frequency resulting from a sequence of the first regulation mode in the second case considered. While in the absence of braking pulses the frequency of the mechanical oscillator is here less than the set frequency F0c = 4 Hz, the frequency of the mechanical oscillator increases as soon as a second series of braking pulses occurs 61. As in the first case, a transient phase is observed before the frequency of the mechanical oscillator stabilizes at a second correction frequency Fcor2 equal to the second frequency FSUPwith FZ (N = 2) = F0c, ie Fcor2 = FSUP (N = 2) and therefore a synchronous phase appears during the second series of braking pulses 61. Thus, during this synchronous phase, there is a synchronization of the mechanical oscillator on the second correction frequency Fcor2 which is slightly higher than the setpoint frequency F0c, which enables correction of the time drift DT, as shown in the lower graph 56B in FIG. 5. In this second case, at the end of a sequence of the first regulation mode, the absolute value of the time drift is reduced relative to the start of the sequence and is here equal to the integer N2L which corresponds to a lower threshold for the time drift , while the integer N2H, which generates the triggering of a second series of braking pulses, corresponds to an upper threshold for time drift (note that the notion of lower threshold and upper threshold is considered in absolute values) .

The regulation circuit is arranged so that each correction period has a duration sufficient for the establishment of the synchronous phase in which the frequency of the mechanical oscillator is synchronized, as a function of a positive or negative drift detected , respectively on a first correction frequency Fcor1 which is equal to the frequency FINF calculated with FZ (N = 2) = F0c or on a second correction frequency Fcor2 which is equal to the frequency FSUP calculated with FZ (N = 2) = F0c.

In a preferred variant, the duration of the synchronous phase is expected to be much greater than a maximum duration of the transient phase, in particular at least ten times greater.

The timepiece according to the invention is remarkable in that a correction of a time drift, detected by the regulation circuit in association with a sensor, is carried out by the generation of a series of braking pulses periodically at a selected frequency close to but different from a frequency FZ (N) = 2⋅F0c / N, N being a positive integer, which makes it possible to regulate the average frequency of the mechanical oscillator so that 'it equals a set frequency F0c without having to manage the instants of triggering of the braking pulses relative to the angular position of the mechanical oscillator as in the prior art. Provision could be made to determine the instant of a first braking pulse of each series of pulses relative to the angular position of the mechanical oscillator to ensure a relatively short transient phase before the stable phase of synchronization, but such a variant is not necessary.

Referring to Figs. 6 to 9, a second embodiment of the invention will be described below and a second mode of regulation according to the invention. In fig. 6, the elements of the watch movement 4A of the timepiece 3 already described above will not be described here again. The regulation device 72 of this second embodiment comprises: a reference time base 36, an electromagnetic braking device 76 for braking the mechanical resonator 14A during correction periods, and a regulation circuit 74 which receives a digital periodic signal SQ from the reference time base and which is arranged to generate series of pulses 84 of short circuit of the coil 78 via a switch 50 (see fig. 8 and 9) respectively during periods of correction of time drifts successively detected by this regulation circuit.

By “electromagnetic braking” is understood a braking of the mechanical resonator generated via an electromagnetic interaction between at least one permanent magnet, carried by the mechanical resonator or a support of this mechanical resonator, and at least one coil carried respectively by the support or the mechanical resonator and associated with an electronic circuit in which a current induced in the coil by the permanent magnet can be generated.

In a general variant (not shown), the electromagnetic braking device is formed by an electromagnetic system which comprises a coil 78 carried by a support 5 of the mechanical resonator 14A and at least one permanent magnet carried by a balance of this resonator mechanical, this electromagnetic system being arranged so that an induced voltage is generated between the two terminals 78A & 78B of the coil in each alternation of the oscillation of the mechanical resonator for a useful operating range of the mechanical oscillator. The regulation device is arranged so as to allow the regulation circuit to temporarily decrease the impedance between the two terminals of the coil, during separate time intervals TP, to generate electromagnetic braking pulses from the mechanical resonator. In the advantageous variant of the second embodiment described with reference to FIGS. 8 and 9, a short circuit of the coil is made during each separate time interval TP.

In the particular variant shown in FIGS. 6 and 7, the electromagnetic system of the electromagnetic braking device comprises a first pair of bipolar magnets 64 & 65 with axial magnetization and opposite polarities. These two bipolar magnets are arranged on the balance 16A symmetrically relative to a reference half-axis 68 of this balance, this reference half-axis defining a zero angular position ("0") when the mechanical resonator is in its neutral position ( state of minimum potential energy). Here we consider a polar coordinate system centered on the axis of oscillation of the mechanical resonator 14A and fixed relative to the plate 5 of the watch movement 3. In general, the coil 78 is arranged with an angular offset relative to the angular position zero so that a voltage induced in the coil intervenes substantially, when the mechanical oscillator oscillates in its useful operating range, in each alternation alternately before and after the passage of the mechanical resonator through its neutral position in this alternation. The angular offset of the coil is defined as the minimum angular distance between the zero angular position and the angular position of the center of the coil. In the useful operating range of the timepiece 3, the extreme angular positions (amplitudes of oscillation) of the mechanical resonator are provided, in absolute values, substantially equal to or greater than the angular offset of the coil. Preferably, as shown in FIG. 7, the angular offset is provided substantially equal to 180 °. It will be noted that the pendulum 16A is shown in FIG. 7 in an angular position θ equal to 90 ° (θ = 90 °).

In FIG. 9 are shown, for an angular offset of 180 ° and for an amplitude of oscillation of the mechanical resonator in the useful operating range of the oscillator, the angular position of the balance 16A (curve 82) over an oscillation period and the induced voltage (curve 86) generated in the coil 78 during this period of oscillation. In the useful operating range of the mechanical oscillator, the electromagnetic system formed by the coil and the first pair of magnets 64 & 65 generates, in each alternation of this mechanical oscillator, two pulses of induced voltage 88A and 88B, namely a pulse 88A in each first half-wave A11, A21 and a pulse 88B in each second half-wave A12, A22. It is noted that the pulses 88A and 88B are separated in pairs by time zones without induced voltage in the coil 28. Thanks to the positioning of the coil with an angular offset of 180 °, the two pulses of induced voltage 88A and 88 B intervening in each alternation have a symmetry relative to the instant of passage of the mechanical resonator 14A through its neutral position.

In an advantageous variant shown in FIGS. 8 and 9, electromagnetic braking pulses are generated by a short circuit of the coil 78 during distinct time intervals TP which are substantially equal to or greater than the time zones without induced voltage in the coil around the two extreme positions of the mechanical resonator for the useful operating range of the mechanical oscillator. In the preferred case (angular offset of 180 ° of the coil), the time zones without induced voltage in the coil around the two extreme positions of the mechanical resonator are substantially equal.

Preferably, the regulating device 72 comprises a supply circuit formed by a storage capacity Cal and a rectifier circuit of an induced voltage (signal SB) in the coil 78 by a second pair of bipolar magnets 66 & 67 carried for this purpose by the pendulum 16A. In fig. 8, this supply circuit is represented as a part of the regulation circuit 74. However, it can also be considered as a specific circuit which is associated with the regulation circuit to supply it. The second pair of bipolar magnets 66 & 67 is momentarily coupled to the coil 28 in each alternation of the oscillation of the mechanical resonator and therefore serves essentially for the electrical supply of the regulation device, although it can intervene in a phase initial transient of each correction period which will be described later. The second pair of bipolar magnets has a middle half-axis 69 between its two magnets which is offset from the angular offset which the coil 78 has relative to the reference half-axis 68, so that this half-axis 69 is aligned with the center of the coil when the mechanical resonator is in its rest position.

The supply circuit is connected, on the one hand, to a terminal of the coil and, on the other hand, to a reference potential (ground) of the regulating device at least periodically when passing through a mechanical resonator by its neutral position, but preferably constantly. The second pair of magnets generates pulses of induced voltage 90a and 90b when the balance 8B passes through the angular position zero, these pulses having a greater amplitude than the pulses of induced voltage generated by the first pair of magnets 64 & 65 and serving to supply the storage capacity, the voltage of which is represented by curve 94 in FIG. 9. The rectifier is provided here at full alternation, so that each central peak of the pulses 90a and 90b recharges the supply capacity.

The control circuit 74 of an advantageous variant of the second embodiment, which implements a second control mode of the invention, is shown in FIG. 8. It receives as input, on the one hand, the periodic reference signal SQ supplied by the clock circuit 38 and, on the other hand, an induced voltage signal SB (curve 86 shown in fig. 9) supplied by the coil 78. On the basis of these two signals, the regulation circuit performs the desired regulation of the running of the timepiece. To do this, it includes a measuring device which includes a divider DIV1 & DIV2 supplying a clock signal Sh, a bidirectional counter CB with two inputs (of the differential type), and a comparator 52 which receives a reference voltage at input URefet the induced voltage signal SB.

As shown in FIG. 9, provision is made to detect in each oscillation period, for the useful operating range of the mechanical oscillator, a negative central peak of an induced voltage pulse 90A occurring once in each oscillation period. The comparator 52 indicates whether the voltage induced in the coil becomes lower than the reference voltage URef (which is negative). It is understood that the value of URefest selected here to be, in absolute values, greater than the amplitudes of the induced voltage pulses 88A and 88B which are generated by the first pair of magnets 64 & 65 and less than the amplitude of the central peaks of the pulses 90a (note that, relative to the amplitudes of the induced voltage pulses 88A and 88B, the central peaks have a higher maximum value than shown in FIG. 9 in the case of an angular offset of 180 ° for the coil). Thus, in the second embodiment, the sensor is preferably formed by an electromagnetic system comprising the coil 78 and an additional pair of magnets 66 & 67 relative to the magnetic system of the braking device.

By analogy with the first embodiment as described, the comparator 52 can also be considered as a part of the sensor and not of the measurement device. It will be noted that, in general, an additional pair of magnets is advantageous but not essential, because in another variant the pulses 88A and 88B can also be used for the electrical supply of the regulation device and also for the detection of the number of alternations or periods of oscillation of the mechanical resonator. In general, the reference voltage is selected so that, in the useful operating range of the mechanical oscillator, the comparator 52 supplies a first predetermined input of the counter CB with a predetermined number of pulses per oscillation period of the resonator mechanical, and the clock signal Sh is provided so that it delivers the same number of pulses per setpoint period T0c (inverse of the setpoint frequency F0c) at a second input of the counter CB. This counter CB, as in the first embodiment, outputs a signal corresponding to its state and which gives a measurement of the time drift DT of the mechanical oscillator relative to the auxiliary oscillator 36.

The state of the counter CB is supplied to two comparators 82 and 84. The first comparator 82 performs a comparison of the state of the counter CB with a first integer N1 greater than zero, to determine whether the measured time drift is greater or not greater than this first number N1, and thus detects whether at least a certain advance has occurred in the operation of the mechanical oscillator. The second comparator 84 compares this state with a second negative integer –N2, N2 being greater than zero, to determine whether the measured temporal drift is less than this second number –N2 or not, and thus detects if at least one some delay occurred in the operation of the mechanical oscillator. The output of the first comparator 82 is supplied to a first frequency generator 42A arranged to generate a first periodic digital signal SFI at the first frequency FINF during a correction period each time this output indicates that the state of the counter CB is greater than the number N1 . More particularly, the first generator 42A of the frequency FINF comprises means arranged to enable it to be activated and then to deactivate it, the signal supplied by the first comparator being supplied to a “start” input of the first generator to activate it as soon as this first comparator indicates that the state of the counter CB is greater than the number N1. Similarly, the output of the second comparator 84 is supplied to a second frequency generator 44A arranged to generate a second periodic digital signal SFS at the second frequency FSUP during a correction period each time this output indicates that the state of the counter CB is less than the number –N2. More particularly, the second generator 44A of the frequency FSUP comprises means arranged to enable it to be activated and then to deactivate it, the signal provided by the second comparator being supplied to a “start” input of the second generator to activate it as soon as the second comparator indicates that the state of the counter CB is less than the number –N2. The first and second periodic digital signals SFI and SFS as well as the frequencies FINF and FSUP have already been described in the context of the first embodiment and have in the second embodiment the same characteristics as in this first embodiment, so that these signals and these frequencies will not be described here again. The control signal SF is similar to that described in the first embodiment; it is formed by the signal SFI when the first frequency generator is activated and by the signal SFS when the second frequency generator is activated.

It is understood that the two frequency generators are never activated simultaneously. The electrical connection point 86 corresponds in practice to an electronic element / for example a logic 'OR' gate, or to an electronic circuit, for example a multiplexer with two or three input positions and a single output (this is so here a switch with two or three inputs). In the case of three input positions, a neutral position is advantageously provided in which the switch is not connected to either of the two frequency generators. As in the first embodiment, the control signal SF is supplied to a timer 48 which outputs the periodic signal SP already described above. For each elementary pulse of the signal SFI or of the signal SFS, corresponding to a period of the respective frequency, the timer generates an activation pulse of the switch 50 which is here a short-circuit switch of the coil 78. Thus, in each period of the signal SFI and of the signal SFS is generated a short-circuit pulse during a time interval distinct from a duration TP.

A counter at N (referenced CN) also receives the control signal SF and it counts the number of elementary pulses (number of periods) in this control signal SF since the start of each correction period. It is therefore reset to zero at the start of any correction period, simultaneously with the activation, as the case may be, of the first or second frequency generator. This counter at N stops the frequency generator which has been activated in the correction period considered as soon as it has counted N elementary pulses (ie N periods) via a 'Stop' input which each of the two frequency generators comprises, N being an integer greater than one (N> 1). In an advantageous variant, the counter at N is then deactivated until the start of a next correction period. Preferably, the number N is much greater than "1", this number N being for example between 100 and 10,000. In each correction period are therefore generated N short-circuit pulses of the coil 78 during N respective separate time intervals each having a duration TP.

Note that we can know approximately which time drift DT (absolute time error) is corrected by a number N of short-circuit pulses generated in a correction period, so that it is easy to select a number N which is in relation to the time drift DT detected. In a preferred variant where the two frequency differences between the reference frequency F0c and respectively the first frequency FINF and the second frequency FSUP are provided with the same value and where the number N1 is equal to the number N2, the number N is chosen so that a detected time drift, negative or positive, is substantially corrected during a correction period which follows its detection. The same result can be obtained with a number N1 different from the number N2 if the two above-mentioned frequency differences are not provided with the same value.

In general, on the basis of the teaching given in the document CH 713 306, it is understood that, on the one hand, the induced voltage pulses 88 generate, if the short circuit pulses 84 of the coil 78 intervene at least partially during these pulses 88A, separate electromagnetic braking pulses which generate negative phase shifts in the oscillation of the mechanical resonator 14A, so that they can generate delay in the running of the timepiece to correct an advance. On the other hand, the induced voltage pulses 88B generate, if short circuit pulses 84 of the coil 78 occur at least partially during these pulses 88B, separate electromagnetic braking pulses which generate positive phase shifts in the oscillation of the mechanical resonator, so that they can generate advance in the running of the timepiece to correct a delay. It will be noted that an angular offset of 180 ° has the advantage of being very effective in generating the braking pulses by the short-circuit pulses 84, which makes it possible to effectively correct an advance or a delay in the operation of the timepiece.

As in the first embodiment, during a correction period during which is generated either a first series of braking pulses by a corresponding first series of short-circuit pulses of the coil, or a second series of braking pulses by a second corresponding series of coil short-circuit pulses, a transient phase is observed in the first part of the correction period (more or less long depending on the case and in particular depending on the moment at which the first short-circuit pulse of the N short-circuit pulses generated at each correction period occurs) during which the instantaneous frequency of the mechanical oscillator passes from the frequency it has before the correction period in question at the selected correction frequency, namely either the FINF frequency (N = 2) or the FSUP frequency (N = 2) depending on the time drift detected that we are correcting. Following the transitional phase, there is a stable phase / synchronous phase in the second part of the correction period. During the synchronous phase, the frequency of the oscillator is synchronized with the selected correction frequency, namely either on the first correction frequency Fcor1 or on the second correction frequency Fcor2. It is therefore observed that, as long as the natural time drift of the timepiece remains within a nominal range for which the electromagnetic braking device of the mechanical resonator has been dimensioned, in each correction period a synchronous phase occurs where the oscillator mechanical has the correction frequency selected through the selection of the braking frequency FINF or FSUP, regardless of the angular position of the balance 16A during a first short-circuit pulse in any correction period. In the synchronous phase, if no particular external disturbance occurs (for example a shock or a certain acceleration of the balance due to a sudden movement), each short-circuit pulse generates an electromagnetic braking pulse, which is not always the case in the transitional phase.

In the synchronous phase, we observe in FIG. 9 that the short-circuit pulses 84 are called between two induced voltage pulses 88Bet 88A Surrounding an extreme angular position of the mechanical resonator and two separate braking pulses occur respectively at the start and at the end of each time interval TP, these two pulses separate braking systems corresponding to two quantities of energy which are taken from the mechanical resonator during a braking pulse corresponding to a short-circuit pulse and which are variable (the variation of one being opposite to the variation of the other, so that if one of the two amounts of energy increases or decreases the other respectively decreases or increases) depending on the frequency difference between the natural frequency FO of the mechanical oscillator and the selected correction frequency and the braking frequency selected. Two braking pulses are distinct when they are separated by a time zone of non-zero duration. By natural frequency FO, we understand the frequency that the mechanical oscillator would naturally present during the correction period considered, that is to say in the hypothetical case of an absence of short-circuit pulses.

It will be noted that, in the definition of the present invention in the descriptive text and the claims, the braking pulses in the second embodiment correspond respectively to the short-circuit pulses which produce them, so that each pulse of braking of a first series of braking pulses and of a second series of braking pulses includes all of the separate braking pulses which can occur during the time interval TP of the corresponding short-circuit pulse. It will also be noted that, in the transient phase, if the time intervals TP are less than time zones with no induced voltage in the coil, it is possible that no braking pulse appears in initial short-circuit pulses. In the synchronous phase of a correction period, a braking pulse may contain only one distinct braking pulse, which is the case when the time interval TP has a duration shorter than that of the time zones without induced voltage. located around the extreme angular positions. In the advantageous variant shown in FIG. 9, each braking pulse intervening in the synchronous phase of a correction period has two distinct braking pulses, respectively at the start and at the end of each corresponding short-circuit pulse which is generated during a time interval TP.

FIG. 9 corresponds to a situation where the natural oscillation frequency FO of the mechanical oscillator is a little lower than the set frequency F0c, so that the timepiece delays in the absence of regulation. In this case, in each period of oscillation during synchronous phases of successive correction periods of a certain delay in the running of the timepiece, a first distinct braking pulse, generated in the initial zone of each pulse short-circuit 84 and intervening in the second half-wave A12 of a first oscillation half-wave A1 (at the start of the separate time intervals TP), is stronger than a second separate braking pulse generated in the final zone of each short-circuit pulse and occurring in the first half-wave A21 of a second half-wave A2 (at the end of the separate time intervals TP). The first and second distinct braking pulses are generated respectively by the induced voltage pulses 88Bet 88A during each short-circuit pulse 84 (respectively at the start and at the end of the separate time intervals TP). Thus, in this case, the positive phase shift generated by a voltage pulse 88B in a half-wave A12 is greater than the negative phase shift generated by the voltage pulse 88 In the following half-wave A21, so that a small correction of the detected delay occurs during each short circuit pulse.

In the situation where the timepiece naturally advances, the reverse is observed, namely that, in the synchronous phase of the correction period, the second distinct braking pulse mentioned above is stronger than the first separate braking pulse during each short circuit pulse, so that a small correction of the detected advance occurs during each short circuit pulse.

Claims (17)

1. Timepiece (2; 3) fitted with a mechanical movement (4) which includes: - a mechanism (6) indicating at least one time datum, - a mechanical resonator (14; 14A) capable of oscillating along an axis of oscillation around a neutral position corresponding to its minimum potential energy state, and - a maintenance device (12) of the mechanical resonator forming with this mechanical resonator a mechanical oscillator which is arranged to clock the progress of the indicator mechanism; the timepiece being further provided with a regulating device which is arranged to regulate the average frequency of the mechanical oscillator and which comprises: - a sensor (24; 66,67,78) arranged to be able to detect a number of alternations or periods in the oscillation of the mechanical resonator in a useful operating range of the mechanical oscillator, - an auxiliary oscillator (23), - a braking device (26; 64, 65, 78) which is designed to be able to apply a braking force momentarily to the mechanical resonator, - a regulation circuit (22; 74) comprising a measuring device (DIV1 & DIV2, CB) arranged to be able to measure, on the basis of a detection signal (Se) supplied by the sensor, a time drift of the mechanical oscillator relative to the auxiliary oscillator, this regulation circuit being arranged to determine whether a measured time drift corresponds to at least a certain advance or at least a certain delay and to be able, if this is the case, to generate a signal control which selectively activates the braking device as a function of the measured time drift, so as to generate at least one braking pulse which is applied to the mechanical resonator to at least partially correct the measured time drift; characterized in that the regulation circuit (22; 74) comprises a device generating at least one frequency which is arranged so as to be able to generate a periodic digital signal at a frequency FSUP; and in that the regulation circuit is arranged to be able to supply, when it determines a time drift corresponding to at least a certain delay in the running of the timepiece, momentarily to the braking device a first control signal to activate this braking device so 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 the frequency FSUP can generate, during the first correction period, a synchronous phase in which the mechanical oscillator is synchronized with a correction frequency (Fcor2) which is greater than a set frequency F0c provided for the mechanical oscillator. 2. Timepiece according to claim 1, characterized in that said frequency FSUP is included in a first range of values extending between (M + 1) / M and (M + 2) / M, inclusive, multiplied by a frequency FZ (N) equal to twice said setpoint frequency F0c divided by a positive integer N, ie [(M + 1) / M] ⋅FZ (N) <FSUP = <[(M + 2) / M] ⋅FZ (N) with the frequency FZ (N) = 2⋅F0c / N, M being equal to a hundred times two to the power K with K equal to a positive whole number greater than zero and less than thirteen, that is to say 0 <K <13 and M = 100 2 <K>, and N being expected to be less than M divided by thirty, ie N <M / 30. 3. Timepiece according to claim 1 or 2, characterized in that said device generating at least one frequency is a frequency generating device arranged so as to be able to further generate a periodic digital signal at a frequency FINF; and in that the regulation circuit is arranged to be able to supply, when it determines a time drift corresponding to at least a certain advance in the running of the timepiece, momentarily to the braking device a second control signal to activate this braking device so that the braking device generates, during a second correction period, a series of periodic braking pulses which are applied to the mechanical resonator at said frequency FINF; this FINF frequency and the duration of the second correction period being provided and the braking device being arranged so that the series of periodic braking pulses at the frequency FINF can generate, during the second correction period, a synchronous phase in which the mechanical oscillator is synchronized with a correction frequency (Fcor1) which is lower than the set frequency F0c. 4. Timepiece according to claim 3, characterized in that said frequency FINF is included in a second range of values extending between (M-2) / M, inclusive, and (M-1) / M multiplied by said frequency FZ (N), ie [(M-2) / M] ⋅FZ (N) = <FINF <[(M-1) / M] ⋅FZ (N). 5. Timepiece according to claim 3 or 4, characterized in that the regulation circuit is arranged to be able to supply, each time the measurement circuit determines a time drift corresponding to at least a certain advance or to at least one certain delay, momentarily at the braking device a control signal which is selectively formed by: A first periodic activation signal of the braking device, which is determined by said periodic digital signal at said frequency FINF, when the time drift corresponds to said at least a certain advance, so as to generate a first series of pulses of periodic braking applied to the mechanical resonator at the FINF frequency, and A second periodic activation signal of the braking device, which is determined by said periodic digital signal at said frequency FSUP, when the time drift corresponds to said at least a certain delay, so as to generate a second series of braking pulses which are applied to the mechanical resonator at the frequency FSUP. 6. Timepiece according to claim 2 or 4, characterized in that the positive integer K is greater than two and less than ten, ie 2 <K <10, and the number N is less than the number M divided by one hundred (N <M / 100). 7. Timepiece according to any one of the preceding claims, characterized in that the braking device (26) is formed by an actuator which comprises a mechanical braking member (28) arranged to be actuated, in response to said control signal. (SF), so as to exert, during the braking pulses, a mechanical braking torque on a braking surface (15) of a pivoting balance (16) that includes the mechanical resonator (14). 8. Timepiece according to claim 7, characterized in that the pivoting balance comprises a clamp (17) which defines the braking surface, which is circular; and in that the mechanical braking member (28) comprises a movable part which defines a brake shoe arranged so as to be able to exert a certain pressure against the circular braking surface (15) during the application of the pulses of mechanical resonator braking. 9. Timepiece according to claim 8, characterized in that the pivoting balance and the mechanical braking member are arranged so that the mechanical braking pulses can be applied mainly by dynamic dry friction between the braking member mechanical and braking surface. 10. Timepiece according to any one of claims 7 to 9, characterized in that the braking surface (15) is configured so as to allow the braking device to start, within a useful operating range of the mechanical oscillator , a braking pulse from each first series of braking pulses and a braking pulse from each second series of braking pulses at any angular position of the mechanical resonator along said axis of oscillation. 11. Timepiece according to any one of the preceding claims, characterized in that the mechanical braking pulses have a duration TP less than a quarter of a set period T0c, ie TP <T0c / 4, T0c being by definition the reverse of the setpoint frequency F0c. 12. Timepiece according to any one of claims 1 to 6, characterized in that the braking device (76) is formed by an electromagnetic system which comprises a coil (78) carried by the mechanical resonator (14A) or a support (5) of this mechanical resonator and at least one permanent magnet (64, 65) carried respectively by this support or this mechanical resonator, the electromagnetic system being arranged so that an induced voltage is generated by said at least one permanent magnet between the two terminals (78A.78B) of the coil in each alternation of the oscillation of the mechanical resonator for a useful operating range of the mechanical oscillator; and in that the regulating device is arranged so as to allow the regulating circuit to periodically decrease the impedance between the two terminals of the coil during separate time intervals (TP) to generate said series of periodic braking pulses at said frequency FINF and said series of periodic braking pulses at said frequency FSUP. 13. Timepiece according to claim 12, characterized in that the electromagnetic system comprises a pair of bipolar magnets (64, 65) with axial magnetization and opposite polarities, these two bipolar magnets being arranged on a balance (16A) symmetrically with respect to a reference half-axis (62A) of this balance, this reference half-axis defining a zero angular position when the mechanical resonator is in its neutral position; and in that the coil is arranged on said support and has an angular offset relative to the zero angular position so that an induced voltage in this coil occurs substantially, when the mechanical oscillator oscillates in its useful operating range, in each alternating alternately before and after the mechanical resonator has passed through its neutral position in this alternation, the extreme angular positions of the mechanical resonator in said useful operating range being, in absolute values, greater than said angular offset which is defined as the minimum angular distance between the zero angular position and the angular position of the center of the coil. 14. Timepiece according to claim 13, characterized in that said angular offset is substantially equal to 180 °. 15. Timepiece according to claim 13 or 14, characterized in that the electromagnetic braking pulses are generated by a short circuit of the coil during the separate time intervals (TP) which are substantially equal to or greater than the duration maximum of time zones without induced voltage in the coil around the two extreme positions of the mechanical resonator for the useful operating range of the mechanical oscillator. 16. Timepiece according to any one of claims 13 to 15, characterized in that it comprises a supply circuit formed by a storage capacity (Cal) and a rectifier circuit of a voltage induced in the coil (78 ) by at least one permanent magnet (66, 67) carried by the balance (16A) and coupled to the coil. 17. Timepiece according to any one of claims 13 to 15, characterized in that the sensor is formed by the coil and at least one permanent magnet (66, 67) carried by the balance and coupled to the coil, this sensor comprising further a comparator (52) receiving, at a first input, a signal (SB) representative of the voltage induced by this at least one permanent magnet and, at a second input, a reference voltage, the latter being selected so that the comparator supplies a bidirectional counter (CB) of the measuring device with a predetermined number of pulses per period of oscillation of the mechanical oscillator for the useful operating range of this mechanical oscillator.