Timepiece fitted with a mechanical movement and a device for correcting the time displayed

Abstract

The watch (2) consists of a mechanical movement incorporating a mechanical resonator (14). It comprises: - a real-time display (12), - a correction device (6) consisting of a detection device (30) for the passage of at least one hand through at least one reference time position and an electronic correction circuit (40) for determining an overall time error for the display, and - a braking device (22A) for the mechanical resonator. The correction device is arranged to correct the displayed real-time according to the overall time error (slow or fast) determined beforehand. To this end, the correction device is arranged so that the braking device can act on the mechanical resonator during a correction period to vary the operation of the display drive mechanism, thereby correcting the displayed real-time.

Description

Domaine technique

[0001] In general, the present invention relates to a timepiece comprising a mechanical movement, a display of a real time which is driven by this mechanical movement, and a device for correcting this real time displayed. Arrière-plan technologique

[0002] In the field of mechanical watches, the classic way of correcting the real time indicated by its display is to use the classic stem-crown which is generally arranged to be able to act, in the pulled-out position, on a wheel set for driving the hour indicator and the minute indicator, thanks to a friction provided in the kinematic chain between these indicators and the escape wheel. Thus, to set a mechanical watch to the real time, it is generally necessary for the user or a robot to pull the stem-crown and rotate it to bring the hour and minute indicators into the respective desired positions, in particular by a visual comparison with a reference clock, such as those found for example in train stations, or with a digital time given for example by a computer.

[0003] Document EP 3 339 982 discloses a device for regulating the rate of a watch movement provided with a mechanical oscillator. The regulating device comprises an auxiliary quartz oscillator, an optical sensor for detecting the vibrations of the mechanical oscillator, a regulating circuit arranged to determine a time drift of the mechanical oscillator relative to the auxiliary oscillator, and a braking device arranged to apply mechanical braking pulses to the balance of the mechanical oscillator, selectively, in different half-vibrations of an oscillation of this mechanical oscillator depending on whether the time drift is negative or positive. Thus, in operation, the average frequency of the mechanical oscillator is maintained around a reference frequency determined by the auxiliary oscillator. Résumé de l'invention

[0004] It is therefore noted that in the field of timepieces equipped with a mechanical movement, in addition to ensuring precise operation of this mechanical movement, a real need exists for a system for effectively correcting the actual time displayed by these timepieces comprising a mechanical movement. In particular, the present invention aims to be able to set the time of a timepiece, comprising a mechanical movement and a time display, with a precision corresponding at least to that of an electronic watch, preferably substantially setting this timepiece to the exact actual time which is given by an external system arranged to provide it (in particular a system connected to an atomic clock), without requiring a user or a robot to actuate a stem-crown or another external control member of the timepiece to perform a time setting of the display itself.Within the scope of the invention, it is provided that the precision of the time setting of a timepiece equipped with a mechanical movement does not depend on a visual assessment by the user who must estimate when the various indicators concerned are in the correct respective positions.

[0005] 'Real time' means the legal time of a given location, in which the timepiece and its user are generally located. The real time is generally displayed in hours, minutes and, where appropriate, seconds. The real time may be indicated with a certain amount of error by a timepiece, particularly of the mechanical type. The real time will also be referred to simply as 'the time', particularly when referring to the real time displayed by a timepiece. To indicate the legal time given with great precision, in particular by / via a GPS system, a telephone network, a long-distance transmitting antenna or a computer / portable device connected in particular to a server on the Internet network receiving the real time from a high-precision clock, the expression 'exact real time' will be used in this text.

[0006] To meet the above-mentioned needs which have been present in the watchmaking field for many years, the present invention relates to a timepiece which comprises: a display of a real time formed by a set of indicators comprising an indicator which is relative to a given time unit of the real time and which indicates the corresponding current time unit, a mechanical movement formed by a drive mechanism of the display and a mechanical resonator which is coupled to the drive mechanism so that its oscillation sets the pace of this drive mechanism, and a device for correcting the real time which is indicated by the display; in which the device for correcting the actual time displayed comprises: a detection device arranged to allow the detection, directly or indirectly, of the passage of said indicator of the display through at least one reference time position of this display which is relative to said time unit of the actual time; an electronic correction circuit, and a device for braking the mechanical resonator;in which the electronic correction circuit comprises: a control unit arranged to be able to control the detection device so that this detection device carries out, during a detection phase, a plurality of successive measurements and provides a plurality of corresponding measurement values, a processing unit arranged to be able to receive from the detection device said plurality of measurement values ​​and process it, and an internal time base comprising a clock circuit and generating a reference real time composed at least of a current reference time unit corresponding to said current time unit of the real time displayed. ;

[0007] Then, according to the invention, the electronic correction circuit is arranged and the duration of the detection phase is provided to allow the detection device to detect, while the drive mechanism is running and clocked by the oscillating mechanical resonator, at least one passage of said indicator through any reference time position of said at least one reference time position. The electronic correction circuit is arranged to be able to determine at least one instant of passage of said indicator through said any reference time position on the basis of at least one measurement value of the plurality of measurement values, this instant of passage being determined by the internal time base and composed at least of the value of said current time unit of reference to said instant of passage.Said electronic correction circuit is further arranged to be able to determine a time error of said indicator, by comparing said at least one passage instant with said reference time position, and an overall time error for the display (namely for all the indicators) as a function at least of said time error of said indicator.

[0008] Furthermore, according to the invention, the control unit is arranged to be able to control the braking device as a function of the determined overall time error. The device for correcting the actual displayed time is arranged in such a way that, when a non-zero overall time error has been determined by the electronic correction circuit, the braking device can act, during a correction period, on the mechanical resonator, as a function of the overall time error, to vary the operation of the display drive mechanism so as to correct at least part of this overall time error, advantageously the major part of this overall time error and preferably substantially all of it.

[0009] By 'braking device' is generally understood any device capable of braking and / or stopping an oscillating mechanical resonator and / or of momentarily holding at rest (i.e. blocking) such a resonator. The braking device may be formed by one or more braking units (one or more actuators). In the case where the braking device is formed by several braking units, in particular two braking units, each braking unit is selected to act on the mechanical resonator in a specific situation relating to the required correction, in particular a first braking unit for correcting a delay and a second braking unit for correcting an advance (the second braking unit being advantageously arranged to be able to momentarily stop and block the resonator).By 'timing the rate of a display drive mechanism', we mean the act of timing the movement of the wheels of this mechanism when it is operating, in particular determining the rotation speeds of these wheels and thus of at least one indicator of the display. In the rest of the text, when the term 'resonator' without a specific qualifier is used, it is to designate a mechanical resonator. We will speak of an oscillating resonator to indicate that we are considering a resonator in its activated state, in which it oscillates while being maintained, via an escapement, by a source of mechanical energy.

[0010] Although the indicators used to display the real time all concern a single physical quantity, time, in this description the hour, the minute and the second are considered as three different time units since they are respectively associated with three distinct indicators. The real time displayed by a display is composed of a current hour, a current minute and a current second which will sometimes be called 'displayed'. The current second displayed has a whole part in seconds and possibly one or more decimals (dial generally without graduation of the decimal, but the decimal part is a fact in an analog display where the almost continuous advance of the hand is normally done in steps cadenced by the escapement at twice the frequency of the oscillating resonator).The displayed current minute has a whole part in minutes (whole number of minutes) and usually a fractional part (sexagesimal part) in seconds (always the case in an analog display of real time). The displayed current time includes at least one whole part (and only this whole part with a 'jumping' hour). The real reference time provided by an internal time base of the electronic type is composed of a current reference hour, a current reference minute and a current reference second. These three components are whole numbers. In addition, the internal time base can optionally provide fractions of a second.In general, the internal time base, which is of the electronic type, provides a real reference time which may be composed of fewer time units than the real time, in particular containing only the current reference minute and the current reference second, possibly in addition a fraction of a current second generated by a clock circuit which forms this internal time base.

[0011] In a main embodiment of the invention, the display comprises an hour indicator giving the current hour, a minute indicator giving the current minute and a second indicator giving the current second of the actual time displayed; and the actual reference time generated by the internal time base is composed of at least one current reference second and one current reference minute. The detection device is arranged to be able to detect the passage of the seconds indicator through at least one first reference time position of the display and the passage of the minutes indicator through at least one second reference time position of this display.The electronic correction circuit is arranged and the duration of the detection phase is provided to allow the detection device to detect during this detection phase, while said drive mechanism is running and clocked by the oscillating mechanical resonator, at least one passage of the seconds indicator through a first reference time position of said at least one first reference position and at least one passage of the minutes indicator through a second reference time position of said at least one second reference time position.

[0012] Then, the electronic correction circuit is arranged to be able to determine, in association with the internal time base and on the basis of measurement values ​​of the plurality of measurement values, at least a first instant of passage of the seconds indicator through said first reference time position, this first instant of passage being determined by the real reference time and composed of at least the value of the current reference second at said first instant of passage, and at least a second instant of passage of the minutes indicator through said second reference time position, this second instant of passage also being determined by the real reference time and composed of at least the value of the current reference minute at said second instant of passage.In addition, the processing unit or the control unit is arranged to be able to determine a first time error for the seconds indicator, by comparing said at least one first passage instant with the first reference time position, and a second time error for the minutes indicator by comparing said at least one second passage instant with the second reference time position. The processing unit or the control unit is further arranged to be able to determine an overall time error for the display as a function of the first time error and the second time error as well as at least one predetermined processing criterion for these first and second time errors.

[0013] In a particular variant, during the detection phase, the detection device is activated so as to carry out the plurality of successive measurements at at least one measurement frequency determined by the clock circuit of the internal time base, this clock circuit providing a periodic digital signal at the measurement frequency directly to the detection device or indirectly to this detection device via the control unit.

[0014] In an advantageous embodiment, the detection device is arranged in the timepiece so as to be able to perform direct detection of the passage of an indicator of the display through at least one corresponding reference time position, this indicator being arranged to be able to be detected itself by the detection device.

[0015] In another embodiment, the detection device is arranged in the timepiece so as to be able to perform indirect detection of the passage of an indicator of the display through at least one corresponding reference time position, the detection device being arranged to be able to detect at least one respective angular position of a wheel integral with the indicator or of a detection wheel, forming the drive mechanism or complementary thereto, which drives or is driven by the wheel integral with the indicator, the detection wheel being selected or configured so as to have a rotation speed lower than that of the wheel integral with the indicator and a gear ratio R equal to a positive integer.

[0016] In an advantageous variant of the preceding embodiment, the indicator considered is a minute indicator and the detection wheel is formed by a minute wheel which is rotated by a cannon pinion carrying this minute indicator. The detection device comprises at least one detection unit associated with the minute indicator and arranged to be able to detect at least a first series of R periodic angular positions of the minute wheel, two adjacent angular positions of the first series having between them an angle at the center equal to 360° / R.

[0017] In a preferred embodiment, the braking device is formed by an electromechanical actuator, arranged to be able to apply braking pulses to the mechanical resonator, and the control unit comprises a device generating at least one frequency which is arranged to be able to generate a periodic digital signal at a frequency F SUP . The control unit is arranged to provide the braking device, when the overall time error previously determined by the electronic correction circuit corresponds to a delay in the displayed time which is intended to be corrected, with a control signal derived from the periodic digital signal, during a correction period, to activate the braking device so that the latter generates a series of periodic braking pulses which are applied to the mechanical resonator at the frequency F SUP .The (duration of the) correction period and thus the number of periodic braking pulses in the series are determined by the delay to be corrected. The frequency F SUP is provided and the braking device is arranged in such a way that the series of periodic braking pulses at the frequency F SUP can generate, during the correction period, a synchronous phase in which the oscillation of the mechanical resonator is synchronized to a correction frequency FS Cor which is higher than a set frequency F0c provided for the mechanical resonator.

[0018] According to an advantageous variant, in which the watch movement comprises an escapement associated with the resonator, the frequency F SUP and the duration of the braking pulses of the series of periodic braking pulses are selected so that, during said synchronous phase, the braking pulses of said series each occur outside a coupling zone between the oscillating resonator and the escapement.

[0019] In a particular embodiment, the timepiece comprises a device for blocking the mechanical resonator. Then, the control unit is arranged to be able to supply the blocking device, when the overall time error determined by the electronic correction circuit corresponds to an advance in the displayed time that is intended to be corrected, a control signal which activates the blocking device so that it blocks the oscillation of the mechanical resonator during a correction period which is determined by the advance to be corrected, to stop the running of the drive mechanism during this correction period.

[0020] According to the present invention, there is provided a timepiece according to claim 1. Preferred embodiments are defined in dependent claims 2 to 45. Brève description des figures

[0021] The invention will be described below in more detail with the aid of the appended drawings, given as non-limiting examples, in which: There Figure 1 represents, partly schematically, a first embodiment of a timepiece according to the invention provided with a mechanical movement, a time display, a detection device for the display, and a device for correcting the displayed time; The Figure 2 is a top view of the timepiece of the Figure 1 ; There Figure 3 is a partial section of the timepiece of the Figures 1 And 2 , according to a first variant of a first embodiment of the detection device; The Figures 4A à 4D are schematic sections of various variants for a light source forming the detection device according to the first embodiment; The Figures 5A et 5B are partial schematic sections of two configuration variants for a hand whose passage over at least one photosensitive detector forming the detection device of the timepiece is intended to be detected. Figures 1 And 2 ; There Figure 6 shows a plurality of measurement values ​​provided by the optical detection device, according to the first embodiment, during a detection phase making it possible to determine a time error of the seconds hand and a time error of the minutes hand; The Figure 7 schematically represents a variant of the device for correcting the timepiece according to the first embodiment; The Figures 8 And 9show, during a correction carried out by a series of periodic braking pulses, the evolution of the oscillation frequency of a mechanical resonator during a period of correction of an advance, respectively of a period of correction of a delay in the time indicated by a display of the timepiece considered, and this for the case of a ratio between the correction frequency and the set frequency relatively close to one; The Figure 10 shows, in the case of a relatively high ratio between the correction frequency and the reference frequency, the oscillation of a mechanical resonator at the beginning of a period of correction of a delay by a series of periodic braking pulses, this correction period having an initial transient phase; The Figure 11 shows, during a correction of a delay carried out by a series of periodic braking pulses, some periods of oscillation of a mechanical resonator during a synchronous phase for two different synchronization frequencies; The Figure 12A shows, for a braking frequency corresponding to a braking pulse by alternating the oscillation of a mechanical resonator, several curves of the maximum relative synchronization frequency as a function of the amplitude of the free oscillation of the resonator and its quality factor; The Figure 12B shows, for a braking frequency which corresponds to one braking pulse per oscillation period of a mechanical resonator, several curves of the maximum relative synchronization frequency as a function of the amplitude of the free oscillation of the resonator and its quality factor; The Figure 13A is a graph giving, for a given setpoint frequency, approximately possible correction frequency ranges, to correct a delay in the time display using short periodic braking pulses, as a function of several braking frequencies selected for the braking pulses; The Figure 13B is a graph giving, for a given setpoint frequency, approximately possible correction frequency ranges, for correcting an advance in the time display using short periodic braking pulses, as a function of several braking frequencies selected for the braking pulses; The Figure 14 partially shows a second embodiment of a timepiece according to the invention; The Figure 15 partially shows a third embodiment of a timepiece according to the invention; The Figure 16 schematically represents a fourth embodiment of a timepiece according to the invention; The Figure 17 schematically represents a fifth embodiment of a timepiece according to the invention; The Figures 18 et 19 show the oscillation of the mechanical resonator during a delay correction period respectively for two variants of the braking device of the timepiece of the Figure 17 ; There Figure 20 is a first partial section through a timepiece according to the invention, which comprises a second embodiment of the detection device for the display, in relation to a first unit for detecting the passage of the seconds hand through a corresponding reference time position; The Figure 21 is a top view of the second wheel of the mechanical movement forming the timepiece of the Figure 20 ; There Figure 22 is a second partial section through the timepiece of the Figure 20 , in relation to a second unit for detecting the passage of the minute hand through a corresponding reference time position; The Figure 23 is a top view of the timer wheel of the mechanical movement forming the timepiece of the Figure 22 ; and The Figure 24 is a top view of the second unit of the timepiece detection device of the Figure 22 . Description détaillée de l'invention

[0022] In reference to the Figures 1 à 7 , a first embodiment of a timepiece according to the invention will be described below, which incorporates a first embodiment of a detection device for the display.

[0023] The timepiece 2 comprises a mechanical movement 4, an analog time display 12, a mechanism 10 for driving this display and a device 6 for correcting the actual time indicated by the display. The timepiece is a wristwatch conventionally comprising a case 220 and a crown 52 forming an external control member to allow manual setting of the display via an internal control stem secured to the crown. Generally, during manual time setting via the stem-crown, the mechanical time correction system acts on a minute wheel in direct engagement with a cannon pinion carrying the minute hand and an hour wheel carrying the hour hand. Thus, the hour and minute hands always maintain a kinematic link even during time setting.Only a shock can possibly cause an angular displacement of one of these two hands relative to the other, by a sliding of a hand on its axis. On the other hand, when setting the time via the stem-crown, the cannon-pinion undergoes friction relative to a wheel or a wheel of the drive mechanism and thus an angular displacement relative to the wheels of this drive mechanism located upstream, and therefore to the second wheel carrying the seconds hand. By construction of usual mechanical movements, the seconds hand does not have a given phase relationship with the minute hand once a time setting via the stem-crown has taken place, that is to say that there is generally no determined temporal / angular relationship between the indication of the current minute and the indication of the current second.When the indicator is precisely aligned with a minute scale (which usually also serves as a second scale when the minute and second hands are coaxial), the seconds indicator has a temporal / angular position that is arbitrary (any undetermined position). This is particularly true for timepieces with a mechanical movement driving an analog time display.

[0024] The mechanical movement comprises a barrel 8 forming a source of mechanical energy for the drive mechanism 10 which is formed by a gear train 11, kinematically linked to the display, a mechanical resonator 14, formed by a balance wheel 16 associated with a balance spring 15, and an escapement 18 coupling this resonator to the drive mechanism so that the oscillation of the mechanical resonator sets the rate of this drive mechanism. The analog display 12 is formed by a dial 32, comprising indexes 36 forming a graduation for displaying the real time, and by hands 34 comprising an hour hand 34H giving the current hour, a minute hand 34M giving the current minute, and a second hand 34S giving the current second of the real time displayed. The hands generally have different shapes, in particular different lengths and / or widths.

[0025] The correction device 6 comprises a detection device 30 for the analog display 12, an electronic correction circuit 40, a communication unit 50 and a device 22, 22A for braking the mechanical resonator 14. The electronic correction circuit 40 comprises: a control unit 48 arranged to be able to control the detection device 30 so that this detection device carries out, during a detection phase, a plurality of successive measurements and provides a plurality of corresponding measurement values, a processing unit 46 arranged to be able to receive from the detection device said plurality of measurement values, via a measurement signal S Ms , and process it, an internal time base 42 comprising a clock circuit 44, this internal time base generating a reference real time TRf composed of at least one current reference second and one current reference minute.

[0026] It should be noted that the present invention is not limited to an analog display of the real time, but may also relate to other displays of the real time, for example a display with a 'jumping hour' and / or in particular a 'jumping minute'. The display is therefore not limited to a system with hands having a quasi-continuous advance. The invention can therefore also be applied in particular to a system with discs or rings and in particular to a display provided through at least one window machined in the dial.

[0027] The timepiece 2 is arranged so as to allow a correction of the real time indicated by its display as a function of an overall time error for this display which is determined inside the timepiece by the electronic correction circuit 40 associated with the detection device 30, which is arranged to be able to detect the passage of the seconds hand 34S through at least a first reference time position of the display and the passage of the minutes indicator 34M through at least a second reference time position of this display. To carry out a correction of the real time displayed, the correction device generally comprises a device for braking the mechanical resonator. In a main variant, the braking device is formed by an electromechanical actuator, for example an actuator of the piezoelectric type 22A.Then, the braking device is controlled by a control unit 48 which transmits to it a control signal S Cmd to control its power supply circuit so as to temporally manage the application of a mechanical braking force on the mechanical resonator 14. In general, the correction device is arranged so that the braking device can act, each time that an overall time error has been determined by the electronic correction circuit, on the mechanical resonator during a correction period to vary the operation of the drive mechanism so as to correct at least in part this overall time error.

[0028] In the variant shown, the actuator 22A comprises a braking member which is formed by a flexible blade 24, which has on two opposite surfaces (perpendicular to the plane of the Figure 1 ) respectively two piezoelectric layers which are each coated with a metal layer forming an electrode. The piezoelectric actuator comprises a power supply circuit 26 for applying a certain voltage between the two electrodes so as to apply an electric field through the two piezoelectric layers, which are arranged so as to bend the blade 24 towards the felloe 20 of the balance 14, when a voltage is applied between the two electrodes, so that the end portion of the blade, forming a movable braking pad, can press against the external circular surface of the felloe and thus exert a mechanical braking force on the mechanical resonator. It will be noted that the voltage can be variable, to vary the mechanical braking force and therefore the mechanical braking torque applied to the balance.Concerning the braking device, reference may be made to document WO 2018 / 177779 for various variants of arrangement of such a braking device in a mechanical watch movement. In a particular variant, the braking device is formed by a blade actuated by a magnet-coil system. In another particular variant, the balance comprises a central shaft which defines or carries a part other than the rim of the balance, for example a disc, defining a circular braking surface. In the latter case, a pad of the braking member is arranged so as to exert pressure against this circular braking surface during the momentary application of a mechanical braking force.

[0029] The first embodiment of the timepiece incorporates a first embodiment of the detection device, described below with reference to Figures 2 à 6 , which is distinguished by the fact that it allows direct detection of the passage of at least one indicator of the analog display 12, relating to a time unit of the real time, by at least one reference time position of this display which is relative to said time unit, this indicator being arranged to be able to be detected itself by the detection device.The description of the first embodiment of the timepiece 2 will be made essentially within the framework of the main embodiment, in which the detection device is arranged to be able to detect the passage of the seconds indicator through at least a first reference time position of the display and the passage of the minutes indicator through at least a second reference time position of this display, and in which the measurements for these two indicators are used in each correction cycle to carry out a correction of the current minute and the current second of the actual time displayed.

[0030] In the advantageous variant shown in the Figure 2 ,the detection device 30 is of the optical type and comprises four detection units 224a, 224b, 224c and 224d which respectively define four reference time positions for the seconds hand 34S (15 s, 30 s, 45 s and 60 s = 0 s) and respectively four reference time positions for the minutes hand 34M (15 min, 30 min, 45 min and 60 min = 0 min). It will be noted that in another variant, a single detection unit is provided or two diametrically opposed detection units are provided. It will also be noted that the variant shown advantageously provides the same detection units for detecting passages of the seconds hand and the minutes hand. However, in another variant, different detection units can be provided for the two hands.

[0031] Generally, the optical detection device comprises at least one light source, each capable of emitting a beam of light, and at least one photosensitive detector each capable of capturing light emitted by a light source of said at least one light source. The seconds indicator and the minutes indicator each have a reflection surface which passes through the beam(s) of light emitted by at least one light source when the indicator in question passes through at least one reference time position corresponding to this indicator and defined by the detection device, in particular opposite at least one detection unit of this detection device.The detection device and the reflection surface are configured so that this reflection surface can reflect, when the indicator considered passes through any reference time position of said at least one corresponding reference time position, incident light, provided by a light source of said at least one light source, at least partially in the direction of a photosensitive detector of said at least one photosensitive detector which is associated with said any reference time position.In a preferred variant, the reflection surface of each indicator considered is formed by a lower surface of this indicator, and said at least one light source and said at least one photosensitive detector are supported by a dial of the timepiece or housed at least partially in the dial, or located under the dial which is then arranged to allow the beam(s) of light to pass through it. In an advantageous variant, the light emitted by said at least one light source is not visible to the human eye. The light source notably emits light in the infrared range.

[0032] There Figure 3 is a partial section of the watch of the Figure 2 , through the detection unit 224a of the optical detection device 30. It will be noted that the four detection units are similar. The watch case is represented by its internal profile 220a. The detection unit 224a comprises an optical sensor 226 formed by a light source 228, which emits a light beam 232, and a photosensitive detector 227 capable of capturing light emitted by the light source, the source and the detector being aligned in a radial direction relative to the central axis of the watch around which the second hand and the minute hand rotate. The optical sensor 226 is arranged under the dial 32 and supported by the plate of the mechanical movement 4.The dial has an opening in which is arranged a glass plate 230 which has on its lower surface a sawtooth profile forming two refraction gratings (series of parallel oblique planes) intended to refract respectively the light emitted by the source 228 and the light incident on the detector 227 after reflection by one or the other of the two hands 34M and 34S. The plate can be made of another substance which has sufficiently good transparency for the light emitted by the source 228, in particular for infrared light if necessary. It will be noted that the plate can also form an upper element of the sensor 226 and then be inserted into the opening of the dial during the assembly of the optical sensor with the dial.

[0033] The optical detection unit 224a is remarkable because the electronic units forming the light source and the photosensitive detector are arranged on a common substrate in a general plane parallel to the dial 32 with the emitted light having a main direction (optical axis) which is perpendicular to this general plane, but the light beam 232 is oblique. An air layer between the wafer and the sensor 226 is an advantage for obtaining a fairly large deflection angle of the light relative to the vertical direction, i.e. perpendicular to the dial. Thanks to such an arrangement, although the light emitted by the source 228 has a vertical optical axis, the reflective areas RS1 and RS2 defined respectively by the two lower surfaces of the second hand 34S and the minute hand 34M are flat and horizontal.Thus, since the lower surfaces of traditional hands are flat and parallel to the dial, the detection device requires little or no intervention on the hands, or even no intervention for metal or metal-coated hands. A polished surface in the RS1 and RS2 areas is an advantage. Note that both hands 34M and 34S are shown, at . Figure 3 , one above the other to help understand the operation of the optical detection unit for each of the two hands; but the detection of the seconds hand is provided in the absence of the minute hand above the detection unit.

[0034] Since photosensitive detectors are often adapted to receive light with oblique incidence (up to a certain angle of incidence), the problem related to the desire for flat and horizontal reflection surfaces for the needles concerns firstly the light source. Figures 4A à 4D four specific variants for the light source of the optical detection units are shown. In the first simple variant, the light source 228a, for example a diode of the LED type (acronym for 'Light-Emitting Diode') or a laser diode of the VCSEL type (acronym for 'Vertical-Cavity Surface-Emitting Laser'), is arranged obliquely on a support. This first variant has the disadvantage of considerably increasing the height of the device. In the second variant, a property of conventional laser diodes of the VCSEL type, non-collimated, is used, which naturally have a light intensity profile, shown in Figure 4B , with a maximum exhibiting an angular deviation relative to the perpendicular direction. Thus, the light beam 232, in a plane passing through its central axis, has two symmetrical main directions having an angular deviation α 0 . A laser diode exhibiting a relatively large angular deviation will be selected. In the third variant, the light source 228c has on its emitting surface a diffraction structure RD which diffracts the light beam mainly in a given oblique direction. Finally, the fourth variant is similar to the variant of the Figure 3 . The light source 228d has on its emitting surface a transparent structure having its upper surface having a sawtooth profile which forms a refraction network RD (series of parallel oblique planes) intended to refract the light emitted by the source 228d. While the planes inclined to the Figure 3 have an angle of approximately 45°, the inclined planes of the refraction grating RD have a smaller angle relative to the horizontal direction (for example 35°), so as to have a refraction angle for the light beam 232 which allows it to pass through the transparent structure.

[0035] Two variants, where a particular treatment of the lower surfaces of the needles concerned is accepted, are shown in Figures 5A et 5B . Note that these two variants can be complementary to the variants described above. Figure 5A , needle 34D has a reflective diffraction grating in an area of ​​its lower surface which passes through the incident beam 232a (beam having a normal direction) as it passes over an optical detection unit. Figure 5B ,the needle 34R has a reflection grating in an area of ​​its lower surface which passes through the incident beam 232a as it passes over an optical detection unit.

[0036] In general, the detection device comprises U detection units for the seconds indicator and Q detection units for the minutes indicator, some of these detection units possibly being common to both hands. In the variant shown, four detection units common to both indicators are provided. The U detection units define U reference time positions X0(u), u = 1 to U, for the seconds indicator, and the Q detection units define Q reference time positions Y0(q), q = 1 to Q, for the minutes indicator. Four detection units for the minutes indicator make it possible to detect this indicator in a time interval of approximately 15 minutes.

[0037] The detection device described above is of the optical type. However, it will be noted that the detection device may be of another type, in particular of the capacitive, magnetic or inductive type. A detection unit of the capacitive, magnetic or inductive type may be subject to the same control as that described for an optical detection unit and the same processing of the measurements carried out may be provided within the framework of a correction cycle according to the present invention; which leads to the same correction of the actual time displayed.

[0038] In reference to the Figure 6 , we will now describe a detection phase, provided at the start of a displayed time correction cycle, for the main embodiment in which the real reference time T Rf generated by the internal time base 42 is composed of at least one current reference second X R and a current reference minute Y R .

[0039] First, the electronic correction circuit 48, 48A is arranged and the duration of the detection phase is provided to allow the detection device to detect during this detection phase, while the drive mechanism 10 ( Figure 1 ) is running and clocked by the oscillating mechanical resonator 14, at least one passage of the seconds indicator 34S through a reference time position from among the reference time positions X0(u), u = 1 to U, and at least one passage of the minutes indicator through a reference time position from among the reference time positions Y0(q), q = 1 to Q. The electronic correction circuit is arranged to be able to determine, in association with the internal time base 42 and on the basis of measurement values ​​from a plurality of measurement values, at least one first passage instant T X0 of the seconds indicator by any reference time position, namedX0, among the reference time positions provided for this seconds indicator, this first passage instant being composed of at least one corresponding value of the current reference second XR, and at least one second passage instant T Y0 of the minute indicator by any second reference time position, named Y0, among the reference time positions provided for this minute indicator, this second passage instant being composed of at least one corresponding value of the current reference minute YR. In the following explanations, it is therefore considered that the seconds hand is detected by a unit for detecting its passage through the reference time position X0, and the minutes hand is detected by a unit for detecting its passage through the reference time position Y0.

[0040] To detect the passage of an indicator through a reference time position, a plurality of measurements are carried out at a measuring frequency F Ms. Each measurement gives a measurement value and occurs at a specific measuring time. To do this, the measurements are carried out over short time intervals. In the case of an optical detection unit of an optical detection device, the light source is periodically activated at the measuring frequency F Ms to generate a plurality of light pulses, and the photosensitive detector provides a plurality of corresponding light intensity values.

[0041] In a first general variant, during the detection phase, the detection device is activated so as to carry out a plurality of successive measurements at at least one measurement frequency which is determined by the clock circuit 44 of the internal time base 42, this clock circuit providing a periodic digital signal at the measurement frequency F Ms directly to the detection device or indirectly to this detection device via the control unit. In a preferred variant, the measurement frequency is variable and the correction device 6 is arranged to be able to detect the passage of the seconds indicator through the reference time position X0 with a first measurement frequency FS Mes and the passage of the minutes indicator through the reference time position Y0 with a second measurement frequency FM Mes which is lower than the first measurement frequency.In a particular variant, the first measurement frequency FS Mes is planned to be less than three times a set frequency F0c for the mechanical resonator 14 and greater than or equal to 1 Hz, i.e. 1 Hz <= FS Mes < 3.F0c, while the second measurement frequency FM Mes is planned to be less than or equal to 1 / 8 Hz (FM Mes <= 1 / 8 Hz).

[0042] It may be advantageous, in order for the detection units to be able to carry out measurements correctly and to slightly increase the accuracy of determining the times of passage of the two hands by their respective reference time positions, for the seconds hand to be substantially stationary during the measurements. If, for example, a mechanical resonator oscillates at substantially 4 Hz and the measuring frequency for the seconds hand corresponds to 4 Hz or 8 Hz, it may be that all the measurements take place during the maintenance pulses of the mechanical resonator and therefore when the escape wheel and also the seconds wheel carrying the seconds hand are rotating.To avoid the majority of measurements occurring when the seconds hand undergoes a small rotational movement, it is provided, in an advantageous variant, that the first measurement frequency FS Mes has a value different from twice the set frequency F0c divided by a positive integer N, i.e. FS Mes ≠ 2·F0c / N.

[0043] In another more advanced variant, the measurement frequency is determined by the mechanical resonator in association with the clock circuit. The device for correcting the actual displayed time then comprises a sensor associated with the mechanical resonator and arranged to be able to detect the passages of the oscillating resonator through its neutral position, corresponding to its position of minimum potential energy. During the detection phase, the detection device is activated and controlled by the control unit associated with the internal time base to carry out a plurality of successive measurements each following the detection of a passage of the mechanical resonator through its neutral position and after a certain time shift since this detection. Preferably, this time shift is between T0c / 8 and 3·T0c / 8, where T0c is the set period which is equal to the inverse of the set frequency.To do this, the clock circuit 44 is arranged to provide the control unit with a periodic signal at a frequency equal to 8 / T0c or close to this value. The sensor provides the control unit with a signal indicating when the mechanical resonator passes through its neutral position. Following this instant, the control unit activates the reception of the signal provided by the clock circuit at the frequency approximately equal to 8 / T0c and counts two rising or falling edges in the periodic signal. At the second edge considered, the control unit triggers a measurement and therefore a light pulse. If desired, the time of each measurement can therefore be known. Since the clock circuit and the mechanical resonator are not synchronized, the time shift will be in the aforementioned range of values. With a phase shift in this range, the anchor wheel is stopped and the seconds hand is thus stationary during the measurements.In this advanced variant, the measurement frequency is equal to 2·F0c if a measurement is made each time a passage of the resonator through its neutral position is detected. If a measurement is made every N detections, the measurement frequency is approximately equal to 2·F0c / N. Note that for the measurement processing described below, it can be assumed that the natural frequency F0 of the resonator is equal to F0c, so that F Ms = 2·F0c / N. If a watch has a large daily error, for example 14 seconds per day, this corresponds to an error of 10 ms for one minute. Since one minute is a sufficient detection period for the seconds hand, such an error is insignificant in calculating a time error for this hand.

[0044] To the Figure 6 is shown a first series of measurements carried out for the detection of the seconds hand at a first frequency FS Ms = 4 Hz, preferably using the advanced variant described above if the set frequency for the mechanical resonator is also equal to 4 Hz, and a second series of measurements at a second frequency FM Ms = 1 / 10 Hz (every 10 seconds to save energy) given that the minute hand rotates 60 times slower than the seconds hand and generally has a greater width. It will be noted that 4 Hz can easily be derived from the clock circuit 44 which is arranged to provide second ticks to the time base for the measurement of the real reference time. The frequency FM Ms is generated by a ten-counter cyclic counter, incremented by the second ticks associated with the control unit.

[0045] The first series of measurements gives a first series of intensity values ​​VS n , n being a positive integer, to which corresponds a first series of measurement times TS n . The second series of measurements gives a second series of intensity values ​​VM k , k being a positive integer, to which corresponds a second series of measurement times TM k . Thus, each measurement corresponds to a pair of values ​​VS n and TS n , respectively VM k and TM k .

[0046] For the processing phase following the detection phase, it is not planned to record the real reference time corresponding to each measurement during the detection phase, but it is planned to number or classify in chronological order the measurements of each series of measurements, and to establish a temporal link with the real reference time. T Rf for each series of measurements. In the case of a numbering which associates a number n, respectively k with each value VS n , respectively VM k , the periodic digital signal at the measurement frequency F Ms (periodic measurement signal) can also be supplied to the processing unit 46 which receives the measurement values ​​via a signal S Ms which the detection device provides to it, directly or via the control unit. In the case of classification in chronological order, the rank of the measurement value can be sufficient to determine the corresponding measurement time. It is known that two successive measurements of the same series are separated by a period T Ms which is the inverse of the measurement frequency F Ms .If for an instant X, respectively Y given by the periodic measurement signal, the control unit or directly the processing unit stores the corresponding real reference time TS Rf,X for the seconds hand, respectively TM Rf,Y for the minutes hand, and if a number of periods of the periodic measurement signal is determined between the stored real reference time and a measurement of rank n, respectively of rank k, then the rank (or number) of each measurement corresponds to a determined real reference time. This temporal relationship can be expressed mathematically as follows: . TS n = n − X / FS Ms + TS Rf , X TM k = k − Y / FM Ms + TM Rf , Y

[0047] A special case concerns X = Y = 0. The control unit waits for a second top which defines an initial time for a series of measurements and as soon as it receives it, on the one hand it activates the detection device or it takes into consideration measurements occurring only since this initial instant, with the exception of this initial instant, and on the other hand it records the real reference time TS Rf,X , respectively TM Rf,0 . Thus, we have: TS n = n / FS Ms + TS Rf , 0 avec n = 1 à N TM k = k / FM Ms + TM Rf , 0 avec k = 1 à K where N and K are the numbers of measurements for the detection of the second hand and the minute hand respectively.

[0048] The processing unit 46 performs processing of each series of measurements to determine the first instant of passage T X0 of the seconds indicator by the reference time position X0 and the second moment of passage T Y0 of the minute indicator by the reference time position Y0.Various methods of processing measurement data can be used. Examples include the two examples related to the Figure 6 , and a simplified example. To determine the value T X0 , since the second hand is relatively thin and turns relatively quickly, an algorithm determines the maximum value VS max to which a rank / number n = ZE corresponds. Thus T X 0 = Z E / FS Ms + TS Rf , 0 To the Figure 6 , T X0 = 10 s et 250 ms T X0 = 10,25 s .

[0049] To determine the value T Y0 , an algorithm determines a width, corresponding to a time interval IT, substantially at mid-height of a symmetrical convex curve C Fit adjusted to the series of measurement values ​​VM k to be able to determine a mid-value of this width, this mid-value defining the instant of passage T Y0 of the middle longitudinal axis of the minute hand by the reference time position Y0, which is defined by the middle radial axis of the detection unit concerned / by the radial alignment direction of the light source and the photosensitive detector. It will be noted that the time interval IT is a characteristic parameter of the indicator concerned which makes it possible to differentiate it from other indicators. In addition, the maximum light intensity detected is also a characteristic parameter of the indicator considered.For data processing, the algorithm implemented in the processing unit advantageously uses the numbers / ranks k corresponding to the values ​​VM k . We observe here that the value T Y0 does not correspond to an integer rank / number (the measurements occurring here only every 10 seconds), but it corresponds to a fractional number ZF intermediate between two adjacent ranks / numbers.

[0050] So T Y 0 = Z F / FM Ms + TM Rf , 0

[0051] To the Figure 6 , T Y0 = 17 minutes and 48 seconds (T Y0 = 17 min; 48 s). T Y0 therefore has an integer value PM Y0 in minutes (integer part of T Y0 ) corresponding to the current reference minute when the indicator passes through the reference time position Y0, to which a value is added PS Y0 in seconds which defines a fractional part for the current minute given by the minutes indicator when the indicator passes through the reference time position Y0, this value PS Y0 corresponding to the current second of reference when the minutes indicator passes through the reference time position Y0. We will thus note T Y0 = ( PM Y0 ; PS Y0 ) . It will be noted that the value PS Y0 may optionally have decimals. In a simplified variant, PS Y0 can be ignored, but then a lot of precision is lost for the minute hand. Thus, in the main embodiment, the time of passage of the minute hand through a reference time position (which generally corresponds to an integer number of minutes) is generally determined with an integer part in minutes and a fractional part in seconds (sexagesimal part), this determination preferably being carried out with an accuracy of the order of a second or less.

[0052] In the two processing methods set out above, in general, the control unit and / or the processing unit is / are connected to the internal time base so as to be able to store the real reference time at at least one given instant of the detection phase. The electronic correction circuit is arranged to be able to determine, during the detection phase, at least a first measurement instant and a second measurement instant corresponding respectively to at least a first measurement and a second measurement from a series of successive measurements, these first and second measurement instants being determined by the internal time base. The first measurement instant is composed of at least a first corresponding value of the current reference time unit and the second measurement instant is composed of at least a second value of this current reference time unit.Then, the electronic correction circuit is arranged to be able to calculate, as a function of said at least one first measurement instant and a second measurement instant and the corresponding measurement values, a third instant which determines the time of passage of the indicator considered by the reference time position concerned.

[0053] In a simplified variant, the time of passage of a needle through a reference time position is determined by comparing each measurement value received by the processing unit directly with a threshold value provided for this needle. As soon as the processing unit detects that the value of a measurement exceeds this threshold value, it assigns the time of this measurement to the time of passage and it records the value of the real reference time directly following this detection. This simplified variant is less precise, but it requires few electronic resources. The electronic correction circuit can therefore be simplified.

[0054] Following the determination of the passage times described above, the electronic correction circuit is arranged to be able to determine a first time error for the seconds indicator, by comparing at least a first passage time of this seconds indicator with a first corresponding reference time position, and a second time error for the minutes indicator by comparing at least a second passage time of this minutes indicator with a second corresponding reference time position. In a general variant, the determination of the first time error and the second time error is carried out by the processing unit which performs a subtraction between the determined passage time and the value of the corresponding reference time position.

[0055] For the seconds indicator and the minutes indicator, the two respective time errors Es et E M are given by: E S = T X0 − X0 ; E M = T Y0 − Y0

[0056] By construction, X0 corresponds to an integer number of seconds and Y0 corresponds to an integer number of minutes, i.e. Y0 = (Y0 ; 0). Es is given in seconds, possibly with one or more decimal places since T X0 is normally determined with decimals (precision better than the second). The processing algorithm may decide to keep, for example, only one decimal place. Like the time of passage T Y0 determined for the minute indicator has an integer part PM Y0 in minutes and a fractional part PS Y0 in seconds, the time error E M is determined with an integer part E Mm in minutes and a fractional part E Ms in seconds (E Ms therefore added to E Mm). Depending on the chosen notation: E M = (E Mm ; E Ms ) . It should be noted that E Ms may have one or more decimal places resulting from the calculation carried out for its determination, but the algorithm generally does not keep a decimal place for the E Ms value in seconds since this value is already a fractional part for the minutes indicator.

[0057] We formally note: E M = E Mm ; E Ms = PM Y0 ; PS Y0 − Y0 ; 0 = PM Y 0 − Y 0 ; PS Y 0 .

[0058] In the example of the Figure 6 : X 0 = 15 s et E S = 10,25 − 15 = − 4,75 s Y 0 = 15 0 et E M = 17 48 − 15 0 = 2 48 , or 2 min and 48 s.

[0059] It is observed that the fractional part E Ms of the time error EM relating to the current minute displayed by the minutes indicator is quite different from the time error Es of the current second displayed by the seconds indicator. As explained previously, this situation is not abnormal for a conventional mechanical movement given that the kinematic link between these two indicators is broken when the display is manually set to the correct time by a user. Thus, a specific problem is highlighted, which generally arises from the following two facts: 1) A real time display is made up of several separate indicators that are used to represent the passage of time. They are therefore all relative to a single physical quantity, time. 2) Traditional mechanical watch movements include a manual time-setting device that momentarily breaks the kinematic link between, on the one hand, the seconds indicator and, on the other hand, the minutes indicator and the hours indicator. Thus, any time difference, between zero and sixty seconds, normally appears between the fractional part of the current minute displayed by the minutes indicator and the current second displayed by the seconds indicator. Consequently, the current minute displayed presents, visibly in the presence of a graduation of minutes and seconds, a fractional part in seconds whose value differs from the whole part of the current second displayed, which is also in seconds.We therefore have a difference in seconds between two displayed data which are both relative to the second.

[0060] In the context of the present invention, it has been provided that the electronic correction circuit can also determine an overall time error. T Err , for the display of a mechanical type watch, as a function of the first time error determined for the seconds indicator, the second time error determined for the minutes indicator, and at least one predefined correction criterion which selects a way of processing the first and second time errors to determine an overall time error for the display of the timepiece.

[0061] In a preferred processing mode for the main embodiment, in a main variant where the minute indicator is of the analog type, two correction criteria are established, namely: Critère No 1 : After correction, the seconds indicator should correctly indicate the current second, i.e. at best. Critère No 2 : After correction, the residual error in seconds for the minutes indicator must be greater than or equal to a selected maximum delay T max , either greater than or equal to - T max

[0062] Thus, in a main variant, it is provided that at least the minute indicator, among the set of indicators, is of the analog type, this minute indicator displaying a positive whole number of minutes and a fractional part which is variable. Then, the timepiece further comprises a time-setting device which is arranged so as to momentarily break the kinematic connection between the minute indicator and the second indicator to carry out a time-setting of said display. Finally, the electronic correction circuit is arranged to be able to determine an overall time error (T Err ) for the display as a function of at least one predefined correction criterion for the second indicator and / or the minute indicator in addition to the first and second time errors relating respectively to the second and minute indicators.

[0063] In a preferred embodiment, the overall time error is determined so as to substantially correct the first time error for the seconds indicator during said correction period.

[0064] In an advantageous variant, the overall time error is determined so that the minute indicator has at the end of the correction period, for the case where this minute indicator then has a time shift corresponding to a delay, at most a maximum delay which is selected from the range of values ​​of the fractional part of the current minute displayed, i.e. between zero and sixty seconds of delay.

[0065] In a preferred embodiment, the processing algorithm implemented in the processing unit 46 for determining the overall timing error T Err is as follows: We calculate a cumulative error EC Ms , relating to the fractional part in seconds of the current minute displayed by the minute indicator, theoretically applying the first correction criterion, namely subtracting the time error Es of the seconds indicator of the fractional part E Ms of the temporal error E M de the minute indicator, or: EC Ms = E Ms - E S We perform the integer division of the cumulative error EC Ms by sixty (this operation is noted 'EC Ms modulo 60'); which gives a quotient Q M (whole number of minutes) and a remainder Rs in seconds (positive). We select a maximum delay T max for the minutes indicator, according to the second correction criterion. We determine an overall error E MG for the relative value per minute in the overall time error T Err , this global error E MG which can take two different values ​​depending on the remainder Rs of said integer division and said maximum delay T max , either : E MG = E Mm + Q M if Rs belongs to the range [ 0 ; 59 - T max ] E MG = E Mm + Q M + 1 if Rs belongs to the range [ 60 - T max ; 59 ] for the case where T max is greater than zero. We define the overall time error to be corrected: T Err = ( E MG ; E S ) where E MG is an integer number of minutes, and Es is formed from an integer number of seconds with possibly one or more decimal places.

[0066] So, in the example of the Figure 6 , by selecting T max = 15 s: E S = − 4,75 s , E M = 2 min ; 48 s ; EC Ms = 48 + 4,75 = 52,75 s EC Ms modulo 60 gives: Q M = 0; Rs = 53 s (rounded value) E MG = E Mm + Q M + 1 = 2 + 0 + 1 = 3 ; T Err = E MG E S = 3 ; − 4,75 .

[0067] It should be noted that the T max = 0 variant corresponds to a special case where it has been decided that the minute hand should not show any delay, but should always be corrected to be exactly at the current reference minute or present a certain advance between '0' and '59' seconds. A selection of T max = 30 s corresponds to a case where the minute hand has a residual error after correction located between a delay of 30 seconds (-30 s) and an advance of 30 seconds (+30 s). A variant with T max = 15 s can prove to be advantageous, a good compromise.

[0068] As a complement, here are three examples (with T max = 15 s): Exemple 1

[0069] E S = 25 s , E M = − 2 min ; 19 s ; EC Ms = 19 − 25 = − 6 s EC Ms modulo 60 donne : Q M = − 1 min ; R S = 54 s E MG = E Mm + Q M + 1 = − 2 − 1 + 1 = − 2 ; T Err = − 2 ; 25 = − 1 ; − 35 Exemple 2

[0070] E S = − 30 s , E M = − 2 min ; 36 s ; EC Ms = 36 + 30 = 66 s EC Ms modulo 60 donne : Q M = 1 ; R S = 6 s E MG = E Mm + Q M = − 2 + 1 = − 1 ; T Err = − 1 ; − 30 Exemple 3

[0071] E S = 5 s , E M = 1 min ; 42 s ; EC Ms = 42 − 5 = 37 s EC Ms modulo 60 donne : Q M = 0 ; R S = 37 s E MG = E Mm + Q M = 1 + 0 = 1 ; T Err = 1 5

[0072] The determination of the overall time error T Err is carried out by the processing unit which then provides it to the control unit for the phase of correction of the time displayed by the timepiece. However, the overall time error can also be calculated by the control unit which then receives from the processing unit the time errors determined for the indicators considered. Thus the correction signal S Cor provided by the processing unit includes either the value T Err , either the values Es And E M . It will be noted that the processing unit and the control unit can advantageously be formed by a single electronic circuit or the same electronic unit. The distinction between these two units is functional, to better explain the various phases of a correction cycle.

[0073] The overall correction of the watch display to be made during a correction cycle is given by -T Err converted entirely to seconds. Thus, in example 1 we will correct by moving the time forward by 95 seconds, in example 2 we will correct by moving the time forward by 90 seconds, and in example 3 we will correct by moving the actual time displayed back by 65 seconds.

[0074] It will be noted that the embodiments described relate to a correction device intended to correct the actual time displayed as a function of two time errors determined respectively for a second hand and a minute hand of a watch equipped with a mechanical movement, but the invention is not limited to this main embodiment. Indeed, in a particular embodiment, a time error is also determined for the hour hand and the intended correction is also as a function of this time error. For the hour hand which is normally in phase with the minute hand and continuously in meshing relationship with this minute hand, only the difference between the current time displayed and a current reference time given by the time base is taken into account to determine the overall time error.

[0075] In another particular embodiment, the timepiece only includes a current hour indicator and a current minute indicator (therefore no indication of the current second). In a preferred variant, only a time error is determined for the minute indicator. In this variant, the overall time error is equal to the time error determined for the minute indicator. It will be noted that in an embodiment where the timepiece also has a second hand, it would be possible to ignore, in one variant, the second indication and only precisely correct the minute hand. However, although such a variant makes it possible to give the real time with a correct indication of the current minute, it makes little sense because the second hand then gives an erroneous indication and its presence seems useless.

[0076] In a simple variant, only the seconds hand is detected and therefore only its possible time error is corrected. For this latter variant to make sense, it must be assumed that the minute hand correctly indicates the current minute. This is a conceivable case if a correction cycle is planned with a sufficiently high frequency, for example once a day or once every two days. However, in the preferred variants, the minute indicator is detected and its possible time error is taken into account for the correction of the actual time displayed, because the error to be corrected does not only depend on the time drift, but also on possible manipulations of the stem-crown pulled out into its time-setting position or on various possible disturbances.

[0077] Finally, the timepiece further comprises a communication unit 50 which is arranged to receive from an external device, an external installation or an external system a synchronization signal S Sync providing an exact real time or an exact real time which is composed only of the exact current minute and the exact current second, given that in the main embodiment only the second and minute indicators are detected and then globally corrected. When it receives an S Sync signal, the communication unit 50 provides the exact real time H RE or said exact real time to the internal time base 42 which then synchronizes the reference real time / the reference real time to the exact real time / this exact real time. The external synchronization system can be a GPS system which gives a legal time very precisely.In this case, the communication unit is formed by a unit for receiving a GPS signal relating to the exact real time. In another variant, the external installation is a long-distance radio-synchronization antenna, as found in particular in Europe and the USA. In this case, the communication unit is formed by a unit for receiving an RF signal. In another variant, which can be complementary to one of the two aforementioned variants, the external device is a portable electronic device, for example a mobile phone or a computer. In this case, the communication unit comprises a BLE (acronym for 'Bluetooth Low Energy') or NFC (acronym for 'Near Field Communication') communication unit.It should be noted that in the latter variant, the exact real time or the exact real time is generally derived from the time base of the external device, which is normally regularly synchronized to a clock giving the exact legal time via the telephone network or via the Internet network.

[0078] In general, the correction device comprises a wireless communication unit which is arranged to be able to communicate with an external system capable of providing the exact real time, the correction device being arranged to be able to synchronize the reference real time with an exact real time, composed of current time units of the exact real time corresponding to those of the reference real time, during a synchronization phase during which the communication unit is activated so as to receive from the external system the exact real time or said exact real time.

[0079] In an advantageous variant, the communication unit is activated periodically by the control unit or directly by the internal time base to receive the exact real time or the exact real time. Thus, the communication unit is activated periodically and automatically, to carry out a synchronization of the reference real time on the exact real time during a synchronization phase. In a preferred variant, it is provided that the user can activate the communication unit in particular via an external control member of the timepiece. The two variants can be combined to have automatic periodic synchronization and the possibility of carrying out synchronization on demand.

[0080] The communication unit is particularly important following a power cut of the internal time base. Thus, the control unit is arranged in such a way as not to carry out any correction cycle if the reference real time has not been synchronized with an external system providing the exact real time and maintained by the internal clock circuit in an uninterrupted manner since a last synchronization phase. In a preferred variant, as soon as the time base is deactivated for one reason or another, this information is recorded in a permanent memory (non-volatile memory) which comprises at least one status bit ('ON' / 'OFF') for the internal time base. Upon a subsequent reactivation of the time base, the status bit retains its 'OFF' value until the correction device synchronizes the time base with the exact real time of an external system, as explained.Before performing a correction cycle, in particular before performing a detection phase, the control unit interrogates the status bit to know its value, and does not perform any detection phase as long as this value is 'OFF'. Only when the value of the status bit is 'ON', the correction device then starts a new correction cycle with a detection phase. If a cycle is interrupted and it is intended to continue it, in particular following a possible interruption of a correction cycle between the processing phase and the correction phase, the control unit can subsequently continue such a correction cycle provided that the previous detection phase has been completed correctly and the real reference time is no longer useful for continuing the correction cycle.

[0081] In an advantageous embodiment, the timepiece comprises an external control member for synchronizing the real reference time with the exact real time, this external control member being operable by a user of the timepiece. The external control member and the correction device are arranged so as to allow a user to activate the correction device so that this correction device performs a synchronization of the real reference time with the exact real time during a synchronization phase. In a particular variant, the external control member is formed by a crown associated with a control stem which also serve to manually set the time of the display.

[0082] Another problem must be examined in relation to a watch having a mechanical movement. As already explained, such a watch conventionally comprises a manual time-setting device via a stem-crown. Thus, it is necessary to prevent a correction cycle by the correction device according to the invention from being disturbed by a manual time-setting (with the exception of a manual control provided for making the hour hand jump by one hour, a manual control which is moreover advantageous for the timepiece according to the invention, in particular for the main embodiment described above). A mechanism can be provided to block the external control member (the stem-crown) so that it cannot modify the position of the minute hand and / or stop the second hand during a correction cycle. This normally requires an electromechanical actuator, which makes the timepiece more complex.An alternative is to provide detection of the movements of the stem-crown, in particular to detect whether this control member is moved to a position corresponding to the time setting with the possibility of modifying the position of the minute hand and / or the second hand. As soon as such detection occurs, the control unit ends the correction cycle in progress. Furthermore, before starting a correction cycle, the correction device detects whether the control member is in the aforementioned manual correction position and the control unit does not start a correction cycle if this is the case and as long as this situation persists. The device for detecting whether the stem is in the time setting position can be easily arranged along the control stem or the time setting mechanism associated with this stem.It is advantageous to opt for capacitive or magnetic detection (by placing a small magnet on the stem or on the associated mechanism). In an advantageous variant, each time the correction device detects that the external control organ has been moved into its time-setting position, it quickly performs a correction cycle as soon as this organ is then replaced in another position (in particular the winding position for a stem-crown).

[0083] To the Figure 7 the correction device of the timepiece is shown according to an advantageous variant of the first embodiment.

[0084] The timepiece comprises an energy harvester 54 which may be formed by various types of devices known to those skilled in the art, in particular a magnetic, light or heat energy harvester, as well as an electricity accumulator 56. In one variant, the magnetic energy harvester is arranged to receive energy from an external magnetic source making it possible to recharge the electricity accumulator 56 without electrical contact. In another variant, the energy harvester is formed by a magnet-coil system making it possible to recover a little energy from the oscillation of the mechanical resonator of the timepiece and therefore from the barrel maintaining this oscillation.In this latter variant, at least one magnet is arranged on the oscillating element of the resonator or on the support of the resonator and at least one coil respectively on said support or on said oscillating element, so that the majority of the magnetic flux generated by the magnet passes through the coil when the resonator oscillates in its useful operating range. Preferably, the magnet-coil coupling is provided around the neutral position (rest position) of the resonator. In another variant, in which the mechanical movement is an automatic movement, the oscillating mass is used to drive a micro-generator producing an electric current which is stored in the accumulator.Note that the energy harvester can also be hybrid, i.e. made up of several different units, notably of the wireless / contactless type, which are designed to recover various energies from various energy sources and transform these various energies into electrical energy.

[0085] The control unit 48A controls a device 22 for braking the mechanical resonator 14, in particular an electromechanical actuator of the piezoelectric type shown schematically in Figure 1. It will be noted that other types of actuators for momentarily applying a braking force to the mechanical resonator may be provided. Optionally, the control unit comprises a circuit 68 for detecting the level of available electrical energy, this detection circuit providing a signal S NE to a control logic circuit 60 to give it information relating to the level of electrical energy available, so that this logic circuit can know whether the correction module has sufficient energy before launching an operation for correcting the displayed time. If this is not the case, the following various options are possible: 1) The timepiece has a transmitter for directly indicating to the user that the accumulator must be recharged to enable a complete correction of the displayed time, for example via an optical (LED) or acoustic signal generated by the transmitter. The timepiece does not make any correction until the electrical energy level is sufficient for a complete correction. 2) The timepiece has a transmitter, in particular a BLE communication unit, for indicating to a mobile phone or other external electronic device that the accumulator must be recharged to enable a complete correction of the displayed time, the mobile phone comprising an application for indicating this information to the user on its electronic display. The timepiece does not make any correction until the electrical energy level is sufficient for a complete correction.The mobile phone can further be used to recharge the electricity accumulator 56, preferably contactlessly, via the energy harvester 54 or via another energy harvesting device suitable for energy transfer by a mobile phone, for example by magnetic induction. 3) The timepiece only makes a partial correction of the displayed time using the energy available in the accumulator 56. According to two variants, it does not transmit any information to the user or it informs the user of this situation via the transmitter mentioned in one or other of the two previous options. 4) The timepiece does not transmit any information and does not make any correction until the level of electrical energy is sufficient for a complete correction.

[0086] In the absence of electrical energy management as indicated above, the timepiece can begin a required correction operation if the available electrical voltage is sufficient and carry out this correction operation as long as the electrical voltage supplied by the power supply circuit 58 is sufficient. In an advantageous variant, provision is made to put the correction device into a standby mode when no correction operation of the displayed time is planned, so as to save the electrical energy available in the accumulator 56. Various parts of the correction module can be activated, as required, only during different periods.

[0087] The control unit 48A of the timepiece 2 comprises a control logic circuit 60 connected to the time base 42 and to the processing unit 46 which provides it, as a correction signal S Cor , with the value of the overall time error T Err determined during the previous processing phase. The control logic circuit is arranged to perform various logic operations during each correction cycle. In addition, the control unit 48A comprises a generator device 62 for generating a periodic digital signal having a given frequency F SUP (the generator device 62 is also called a 'frequency generator' or simply a 'generator' at the frequency F SUP ).Depending on whether the overall time error T Err to be corrected corresponds to a delay (negative T Err) or to an advance (positive T Err) in the display of the real time, the control logic circuit 60 generates respectively either two control signals S1 R and S2 R , which it supplies respectively to the frequency generator 62 and to a time counter 63 ('timer'), or a control signal SA which it supplies to a time counter 70. The time counters 63 and 70 are programmable and are used to measure a planned correction period, respectively a period PR Cor for the correction of a delay and a period PA Cor for the correction of an advance. By definition, an advance corresponds to a positive error and a delay corresponds to a negative error.

[0088] The arrangement of the control unit 48A for correcting a detected delay in the time display during a correction phase following the detection and processing phases described previously will be explained below firstly, and subsequently the arrangement of this unit for correcting an advance during a correction phase.

[0089] In the case of a negative overall time error corresponding to a delay, provision is made, according to a first mode of correction of a delay, to generate a series of periodic braking pulses at a frequency F SUP , these periodic braking pulses being applied by the braking device 22, in particular by the actuator 22A to the oscillating resonator. To do this, the control logic circuit 60 activates the frequency generator 62 via the signal S1 R and the time counter 63 which counts up or down a time interval corresponding to a correction period PR Cor whose duration (value) is determined by the logic circuit (by definition, the expression 'time counter' includes a time counter at a given time interval and also a time downcounter to zero from this given time interval which is initially introduced into this time downcounter).

[0090] In the variant shown, when the frequency generator is activated, it provides a periodic digital signal S FS , at the frequency F SUP , to another time counter 64 (timer at a value Tp corresponding to a duration selected for the periodic braking pulses). The outputs of the timers 63 and 64 are supplied to an 'AND' logic gate 65 which provides as output a periodic activation signal S C1 to periodically activate the braking device 22, during the planned correction period PR Cor, via an 'OR' logic gate 66 or any other switching circuit making it possible to transmit the periodic activation signal S C1 to the braking device. The periodic activation signal S C1 forms the control signal S Cmd in the case of a correction of a delay detected in the time displayed by the timepiece.Thus, the braking device applies periodic braking pulses to the mechanical resonator at the frequency F SUP during a correction period PR Cor whose duration (value) depends on the delay to be corrected. Generally, the braking pulses have a dissipative character because part of the energy of the oscillating resonator is dissipated during these braking pulses. In a main embodiment, the mechanical braking torque is applied substantially by friction, in particular by means of a mechanical braking member exerting a certain pressure on a braking surface of the resonator, preferably a circular braking surface, as explained previously during the description of the timepiece 2 with reference to the . Figure 1 .

[0091] Preferably, as for the variant shown in the Figure 1 , the system formed by the mechanical resonator and the braking device of this resonator is configured so as to allow the braking device to start, within the useful operating range of the oscillating resonator, a mechanical braking pulse substantially at any instant of the natural oscillation period of the oscillating resonator. In other words, one of the periodic braking pulses can start substantially at any angular position of the oscillating resonator, in particular the first braking pulse occurring during a correction period.

[0092] According to the teaching given by document WO 2018 / 177779 already cited above, it is possible to precisely regulate the average frequency of an oscillating resonator by continuously applying periodic braking pulses to it at a braking frequency F FR advantageously corresponding to twice the set frequency F0c divided by a positive integer N, i.e. F FR = 2·F0 C / N. The braking frequency F FR is proportional to the set frequency F0c for the mechanical resonator and depends only on this set frequency as soon as the positive integer N is given.It is learned from document WO 2018 / 177779 that, after a transient phase occurring at the start of the activation of the braking device applying the periodic braking pulses at the braking frequency F FR , a synchronous phase is established during which the oscillation of the mechanical resonator is synchronized, on average, on the set frequency F0c, provided that the braking torque applied by the braking pulses and the duration of these braking pulses are selected so that the braking pulses occur, during the synchronous phase, when the mechanical resonator passes through extreme positions of its oscillation, that is to say that the reversal of the direction of the oscillation movement occurs during each braking pulse or at the end of each braking pulse.The latter situation occurs in the advantageous, notably safer, case where the mechanical resonator is stopped by each braking pulse and then remains blocked by the braking device until the end of this braking pulse.

[0093] Although of little interest, document WO 2018 / 177779 indicates that synchronization can also be obtained for a braking frequency F FR whose value is greater than twice the set frequency (2F0), in particular for a value equal to M·F0 with M being an integer greater than two (M > 2). In a variant with F FR = 4·F0, there is just an energy loss in the system without effect during the synchronous phase, because one pulse out of two occurs at the neutral point of the resonator; which is disadvantageous. For a higher braking frequency F FR, the pulses in the synchronous phase which do not occur at the extreme positions cancel their effects two by two. It is therefore understood that these are theoretical cases without much practical interest.It should be noted that other braking frequencies can lead to synchronization of the resonator on the set frequency, but the conditions for implementing the regulation process are much more delicate and difficult to implement.

[0094] In the context of the development which led to the present invention, it has been highlighted that the remarkable phenomenon highlighted in document WO 2018 / 177779 can be used not only to continuously synchronize a resonator to its set frequency, but also to vary in a determined manner the oscillation frequency of a resonator in two frequency ranges located respectively below and above its set frequency; that is to say that it is possible to impose a determined average frequency on a mechanical resonator which is different from its set frequency, higher or lower,by applying periodic braking pulses which can synchronize this resonator on a frequency different from the set frequency but sufficiently close to the latter to allow the establishment of a synchronous phase between the oscillating resonator and the braking device generating the braking pulses at a frequency selected for this purpose, while maintaining the oscillating resonator in a functional regime to regulate the running of the timepiece. The present invention proposes to use this remarkable discovery to carry out a correction of the time displayed by a timepiece by varying the running of the mechanical watch movement considered, that is to say by varying the frequency of the resonator which regulates the running of the mechanism driving the display of the timepiece in question during a given correction period.,

[0095] In particular, in the first embodiment of the electronic control unit described here, provision is made to correct a detected delay in the displayed time according to a first delay correction mode in which, during a correction period PR Cor , the oscillating resonator is synchronized to a correction frequency FS Cor which is higher than the set frequency F0c. It has been demonstrated in the context of the development leading to the present invention that, similarly to the case of synchronization to the set frequency, the best results are obtained, for a correction frequency higher or lower than the set frequency, when the braking frequency F Bra is selected, for a given correction frequency F Cor, so as to satisfy the following mathematical relationship: F Bra = 2 ⋅ F Cor / N , where N is a positive integer.

[0096] Thus, the periodic braking pulses are applied to the mechanical resonator at a braking frequency F Bra advantageously corresponding to twice the correction frequency F Cor divided by a positive integer N, preferably low. This relationship is valid for a correction frequency F Cor = FS Cor which is higher than the set frequency and also for a correction frequency F Cor = FI Cor which is lower than the set frequency (first mode of correction of an advance which will subsequently occur in another embodiment of a timepiece according to the invention). The braking frequency F Bra is therefore proportional to the intended correction frequency F Cor and depends only on this correction frequency as soon as the positive integer N is selected. By 'synchronization on a given frequency' is meant an average synchronization on this given frequency.This definition is important for a number N greater than two. For example, in the case N = 6, we have only one oscillation period out of three which undergoes a variation in its duration, relative to the set period T0c = 1 / F0c (in fact relative to the natural / free oscillation period T0 = 1 / F0), via a time shift generated by each braking pulse in the oscillation of the resonator.

[0097] It will be noted that, as in the case of synchronization on the set frequency, other braking frequencies can make it possible to obtain, under certain conditions, synchronization on a desired correction frequency, but the selection of a braking frequency F Bra = 2·F Cor / N makes it possible to obtain synchronization on the frequency F Cor more efficiently and with greater stability. In general, the mathematical relationship between the braking frequency and the correction frequency is F Bra = (p / q)·F Cor with p and q two positive integers and the number q advantageously greater than the number p. The person skilled in the art can experimentally establish a list of the fractional numbers p / q which are appropriate and under which conditions (in particular for which braking torque).

[0098] It should be noted that braking pulses can be applied with a constant torque or a non-constant torque (for example, substantially in a Gaussian or sinusoidal curve). By 'braking pulse' is meant the momentary application of a torque to the resonator which brakes its oscillating member (balance), i.e. which opposes the oscillating movement of this oscillating member. In the case of a variable torque, the duration of the pulse is generally defined as the part of this pulse which presents a significant torque to brake the resonator, in particular the part for which the torque is greater than half the maximum value. It should be noted that a braking pulse can present a strong variation. It can even be chopped and form a succession of shorter pulses.Generally, the duration of each braking pulse is expected to be less than half of a setpoint period T0c for the resonator, but it is advantageously less than a quarter of a setpoint period and preferably less than T0c / 8.

[0099] To Figures 8 et 9 are represented, for a mechanical resonator having a set frequency F0c = 4 Hz and exhibiting an oscillation 72, respectively a first series of periodic braking pulses 74 applied to the resonator at a frequency F INF = 2·FI Cor with Fl Cor = 0.99975·F0c = 3.999 Hz, for the case of a natural frequency F0 = 4.0005 Hz, and a second series of periodic braking pulses 76 applied to the resonator at a frequency F SUP = 2·FS Cor with FS Cor = 1.00025·F0c = 4.001 Hz, for the case of a natural frequency F0 = 3.9995 Hz. The graphs below the Figures 8 , 9show the evolution of the oscillation frequency of the resonator during a correction period, which is defined as the period during which the braking pulses at the frequency F INF or F SUP are applied to the resonator. Curve 78 shows the evolution of the oscillation frequency of the mechanical resonator during the application of the first series of periodic braking pulses 74 for a correction of an advance detected in the displayed time, the braking frequency F INF leading to a correction frequency FI Cor , given by the synchronization frequency, which is lower than the set frequency F0c (first mode of correction of an advance).Curve 80 shows the evolution of the oscillation frequency of the mechanical resonator during the application of the second series of periodic braking pulses 76 for a correction of a delay detected in the displayed time, the braking frequency F SUP leading to a correction frequency FS Cor, given by the synchronization frequency, which is higher than the set frequency (first mode of correction of a delay).

[0100] The very short correction period at Figures 8 And 9 was taken to be able to show a complete correction period while having a representation of the oscillation of the resonator and the periodic braking pulses which is clearly visible on the graph giving the angular position of the resonator as a function of time. Indeed, in a few seconds, the possible correction is relatively small, in practice less than one second. For the correction frequencies chosen at Figures 8 And9 , the correction is therefore very small. Thus, if the natural frequencies (natural / free frequencies) of the oscillating resonator are here within the norm for a mechanical watch, since they correspond to a daily error of approximately 10 seconds per day (advance, respectively retardation), the correction frequencies are given purely as examples and are much closer to the set frequency than the correction frequencies which are generally provided for the implementation of the first mode of correction of an advance or retardation. In conclusion, the Figures 8 And 9are given only schematically to generally explain the behavior of the oscillating resonator when subjected to a series of periodic braking pulses at a correction frequency close to the set frequency, but different from it, and in the case of a natural frequency leading to a classical time drift. More detailed and precise considerations relating to possible correction frequencies will be explained later.

[0101] In the two graphs showing the frequency curves 78 and 80, at the beginning of the correction period, a transient phase PH Tr is observed during which the frequency varies before stabilizing at the frequency FI Cor, respectively FS Cor during a synchronous phase PH Syn which follows the transient phase. In both cases shown, the transient phase PH Tr is relatively short (less than 2 seconds) and the frequency changes in the direction of the desired correction frequency. In both cases shown, the average correction per unit of time during the transient phase is approximately equal to that which occurs during the synchronous phase. However, it should be noted that the transient phase can be longer, for example from 3 to 10 seconds, and the frequency changes during the transient phase vary from case to case so that the average correction is variable and not determined, but it remains practically small.We can refer to the . figures 9 à 11 of document WO 2018 / 177779 where the transient phases to synchronize the resonator on the set frequency F0c, from a close but different natural frequency, are longer. It will be noted that at the figure 10 of this document, while the set frequency is higher than the natural frequency of the resonator, the oscillation frequency begins to decrease at the beginning of the transient phase before increasing to finally exceed the natural frequency and stabilize at the set frequency.

[0102] The duration of the transient phase and the evolution of the frequency during this transient phase depend on various factors, in particular the braking torque, the duration of the pulses, the initial amplitude of the oscillation, and the instant at which the first braking pulse occurs in an oscillation period. It is therefore difficult to control the time difference resulting from a transient phase relative to the set frequency. For example, if F Cor = 1.05 F0c = 4.2 Hz and the transition phase lasts a maximum of 10 seconds, and if we assume that the average frequency during this transition phase is equal to F0c, then the absolute time difference with respect to F Cor is at most half a second. This uncertainty therefore causes a small error in the correction generated during a correction period, but it is not negligible. We will see later a solution to avoid such an error.In the first embodiment of the electronic control unit, there is therefore a small possible error in the correction obtained if the correction period PR Cor is determined (the duration of) only on the basis of the overall time error T Err to be corrected, by defining this correction period as the period during which a series of periodic braking pulses at the intended braking frequency are applied to the resonator, and by assuming that the oscillation frequency during the correction period is that of the synchronization frequency.

[0103] The synchronization frequency determines the correction frequency. By definition, the correction frequency F Cor is equal to the synchronization frequency. It should be noted that, in the synchronous phase of the correction period, the duration of the braking pulses must be sufficient for the braking torque applied to the resonator to allow it to stop (passing through an extreme angular position, defining its instantaneous amplitude) during or at the end of each braking pulse. In the case of a synchronization frequency higher than the set frequency to correct a delay, the time interval during which the resonator remains stopped during a braking pulse reduces the possible correction per unit of time, so that it is preferable to limit this time interval, taking into account a certain safety margin, to have a shorter correction period thanks to a higher synchronization frequency.It should be noted that the frequency of the braking pulses, the maintenance energy supplied to the resonator at each alternation of its oscillation and the value of the braking torque are involved in the time interval necessary to stop the oscillating resonator. For a given braking frequency and the resulting correction frequency, the person skilled in the art will be able to determine, in particular experimentally or by simulations, a braking torque and a duration for the braking pulses so as to optimize the braking system. For set frequencies between 2 Hz and 10 Hz, braking torques between 0.5 µNm and 50 µNm and braking pulse durations between 2 ms and 10 ms generally prove appropriate for the correction frequencies that are practically advantageous to use (these ranges of values ​​being given as examples and are in no way limiting).

[0104] Based on the assumption mentioned above, namely that the synchronization frequency occurs over the entire correction period PR Cor , the value of the correction period to be expected can be determined on the basis of the overall time error T Err to be corrected, the set frequency F0c and the correction frequency F Cor ; and since the synchronization frequency determines the correction frequency which is equal to it, the value of the correction period to be expected can also be determined on the basis of the overall time error T Err to be corrected, the set frequency F0c and the braking frequency F Bra . By definition, as already indicated, an advance in the time display corresponds to a positive error while a delay corresponds to a negative error. The following mathematical relationships are obtained to determine the value / value of the correction period: P Cor = T Err ⋅ F0c / F0c − F Cor = 2T Err ⋅ F0c / 2F0c − N ⋅ F Bra

[0105] In the first mode of correction of a delay (negative error), the correction frequency F Cor = FScor is greater than F0c, so that P Cor is positive. In this case the braking frequency F Bra = F SUP . We then have the relationship: PR Cor = T Err ⋅ F0c / F0c − FS Cor = 2T Err ⋅ F0c / 2F0c − N ⋅ F SUP

[0106] In the first mode of correction of an advance (positive error), the correction frequency F Cor = FI Cor is less than F0c, so that P Cor is positive. In this case the braking frequency F Bra = F INF . We then have the relationship: PA Cor = T Err ⋅ F0c / F0c − FI Cor = 2T Err ⋅ F0c / 2F0c − N ⋅ F INF

[0107] Following the general presentation relating to a correction of the rate of a mechanical timepiece obtained by a series of periodic braking pulses applied to its resonator, we can return to the first embodiment of the timepiece according to the invention. The control unit 48A ( Figure 7 ) is arranged to provide the braking device, each time the overall time error T Err corresponds to a delay in the displayed time that is intended to be corrected, with a control signal S C1 derived from the periodic digital signal S FS provided by the frequency generator 62, during a correction period PR Cor , to activate the braking device 22 so that this braking device generates a series of periodic braking pulses which are applied to the resonator at the frequency F SUP . Since (the duration of) the correction period is determined by the delay to be corrected, the number of periodic braking pulses in the series of periodic braking pulses is therefore also determined by the delay to be corrected.The frequency F SUP is provided and the braking device is arranged in such a way that each series of periodic braking pulses at the frequency F SUP can generate, during the corresponding correction period, a first synchronous phase in which the oscillation of the resonator is synchronized (by definition 'average synchronized') on a correction frequency FScor which is higher than the set frequency F0c provided for the mechanical resonator.

[0108] In reference to the Figures 10 à 13B ,some observations relating to the braking pulses will be set out below, in particular concerning the braking frequencies F Bra and the corresponding correction frequencies F Cor which are advantageously envisaged in a preferred variant of the first mode of correction of a delay, and also in a preferred variant of a first mode of correction of an advance (which will be implemented in an embodiment described subsequently) in which it is provided to correct an advance detected in the time displayed by a series of braking pulses at a frequency F INF , already defined previously, resulting in a correction frequency FI Cor , also defined previously, which is lower than the set frequency F0c.

[0109] There Figure 10 shows a first part of a correction period with a relatively high ratio between the correction frequency FS Cor = 3.5 Hz and the set frequency F0c = 3.0 Hz (substantially equal to the natural frequency of the resonator when it is freely oscillating, represented by the oscillation 82), namely a ratio RS = FS Cor / F0c = 3.5 / 3.0 = 1.167. When braking pulses 84 are applied to the mechanical resonator with a braking frequency F Bra = F SUP = 2 FS Cor = 7.0 Hz (case N = 1) and a sufficient braking force torque, allowing in the transient phase PH Tr to sufficiently reduce the amplitude of the oscillation 86 of the oscillating resonator to finally stop it during each braking pulse, the corresponding correction frequency, i.e. FS Cor = 3.5 Hz, can be imposed on this resonator relatively quickly.It will be noted that in the example given, the desired synchronization is already obtained after one second, but a PHst phase of stabilization of the oscillation occurs at the beginning of the synchronous phase PH Syn. In the case shown, the amplitude increases again during the stabilization phase to finally stabilize at an amplitude corresponding to approximately one third of the initial amplitude of the free resonator.

[0110] A demonstrator (a prototype of the timepiece according to the invention) was produced for the case presented in the Figure 10 . By applying periodic braking pulses at the frequency F SUP = 7.0 Hz to the mechanical resonator, a 7-hour advance on the timepiece display was obtained for a 6-hour correction period, and this in a very precise manner. This 'gained' precisely 1 hour in 6 hours of time. Such a result opens up prospects for corrections to the time indicated by the display which are other than corrections of a temporal drift of this display due solely to the inaccuracy of the resonator operating freely (i.e. in the absence of braking pulses).

[0111] There Figure 11 shows the free oscillation 82A of a mechanical resonator, a first oscillation 86A of this resonator in a synchronous phase of a correction period where the ratio RS between the correction frequency FS Cor and the set frequency F0c is relatively low (i.e. relatively close to '1'), and a second oscillation 86B of this resonator in a synchronous phase of a correction period where the ratio RS between the correction frequency FScor and the set frequency F0c is relatively high (i.e. relatively far from '1'). The first oscillation 86A results from a series of periodic braking pulses 84A of relatively low intensity and occurring once per oscillation period (which corresponds to the case N = 2 with F SUP = FScor).On the other hand, the second oscillation 86B results from a series of periodic braking pulses 84B of relatively high intensity and occurring once per alternation of the oscillation (which corresponds to the case N = 1, i.e. F SUP = 2·FS Cor ).

[0112] By appropriately selecting the braking torque and the braking frequency, it is observed that the correction frequency can vary continuously between the set frequency F0c and a certain upper frequency FSC max , for the correction of a delay in the displayed time, and continuously between the set frequency F0c and a certain lower frequency FIC max , for the correction of an advance in the displayed time. The upper frequency FSC max and the lower frequency FIC max are not values ​​that can be easily calculated theoretically. They must be determined practically for each timepiece. It will be noted that although this information is interesting, it is not necessary.What is important is that the braking frequencies are selected and the braking torques available are suitable to generate during each correction period, preferably fairly quickly, a synchronous phase during which the mechanical resonator can oscillate at the correction frequency provided by the mathematical relationship given above, without being stopped in its oscillation (i.e. it is necessary to avoid stopping the resonator so that it can no longer start from the stopped position, which would lead to a stoppage of the display drive mechanism).

[0113] On the Figure 11 a safety angle θ Sec is indicated below which, in absolute value, stopping the mechanical resonator will be avoided (i.e. between -θ Sec and θ Sec ), and therefore above which the amplitude, in absolute value, must practically remain during the synchronous phase, at least after the stabilization phase. Advantageously for the operation of the mechanical resonator, the angle θ Sec is provided equal to or, preferably, greater than an angle θ ZI (see Figure 14 ) which corresponds to the coupling angle between the resonator and the escapement associated with it, on one side and the other side of the neutral position of the resonator defined by the angular position of the coupling pin carried by the balance wheel plate when this resonator is at or passes through its rest position. We thus declare 'forbidden zone', to stop the mechanical resonator during a braking impulse, the angular coupling zone (-θ ZI to θ ZI ) between the mechanical resonator and the escapement (we will note that it is possible to brake in this forbidden zone during the transient phase, but we will avoid stopping the resonator in this forbidden zone). We will note that, in the useful operating range of the resonator, it may be necessary, to maintain correct operation of the escapement and in particular to ensure the release phase, for the safety angle θ Sec to be greater than the coupling angle θ ZI .The person skilled in the art will be able to determine a value for the safety angle θ Sec for each mechanical movement associated with a correction device according to the first embodiment. The coupling angle θ ZI may vary from one mechanical movement to another, in particular between 22° and 28°.

[0114] The condition of non-blocking of the resonator in the safety angular zone during the period of correction of a delay is important because a counting of the flow of time via the escapement (i.e. the timing of the running of the mechanism driving the time display) must continue during this period of correction of a delay. Thus, very advantageously, said frequency F SUP and the duration of the periodic braking pulses are selected so that, during said synchronous phase of a correction period within the framework of the first mode of correction of a delay, the periodic braking pulses each occur outside a coupling zone between the oscillating mechanical resonator and the escapement, preferably outside a safety zone defined for the mechanical movement.The same applies to the selection of the said frequency F INF and the duration of the periodic braking pulses in the first mode of correction of an advance.

[0115] To guide the person skilled in the art in the choice of correction frequencies and corresponding braking frequencies, a mathematical model has been established based on the equation of motion of a mechanical oscillator. To determine a maximum correction, positive or negative, the resonator is considered in a synchronous and stable phase. Then, a simplification is introduced for the sustaining force applied to the resonator by the energy source via the escapement, considering it to be of the cos(ωt) type. It will be noted that this simplification is prudent in that it reduces the maximum value relative to the real case where the entire energy supplied to the resonator occurs in the forbidden zone θ ZI defined previously.Finally, we consider the duration of the braking pulses to be very small, in fact punctual, by defining the braking frequency F Bra as the inverse of the time value T Sec at which the resonator reaches, in the equation of motion given below, the safety angle θ Sec in the half-wave corresponding to the number N selected in the relation F Cor = N·F Bra / 2.

[0116] To find the maximum correction and thus the minimum or maximum period depending on whether the time error to be corrected is negative (delay) or positive (advance), the time t=0 is given by a braking pulse during which the oscillator is stopped at the safety angle θ Sec . Then, in the stable synchronous phase, the resonator must stop at the next braking pulse at the earliest, respectively at the latest also at the safety angle (-1 N< )·θ Sec in a time range given by the value of N and by the fact that the correction frequency is planned higher or lower than the set frequency F0c to correct the delay or the advance.

[0117] In this case, the equation of motion is given by: θ t = θ 0 + θ Sec − θ 0 e − t τ × cos 2 πf 0 t where τ = Q·T0 / π , T0 is the free oscillation period (considered equal to T0c = 1 / F0c for calculations) and θ 0 is the amplitude of free oscillation.

[0118] We therefore observe that the quality factor Q of the mechanical resonator intervenes in the equation of motion.

[0119] To obtain a correction frequency FS Cor higher than the set frequency F0c, T Sec must intervene in an alternation after the resonator has passed through its neutral / rest position. We therefore have for a given N: θ T Sec = − 1 N θ Sec avec T Sec ∈ 2 N − 1 4 T 0 , N 2 T 0

[0120] The maximum braking frequency FSB max (N) = 1 / T Sec and the maximum correction frequency FSC max (N) = N·FSB max / 2.

[0121] To obtain a correction frequency FI Cor lower than the set frequency F0c, T Sec must intervene in an alternation before the resonator passes through its neutral / rest position. We therefore have for a given N: θ T Sec = − 1 N θ Sec avec T Sec ∈ N 2 T 0 , 2 N + 1 4 T 0

[0122] The minimum braking frequency FIB min (N) = 1 / T Sec and the minimum correction frequency FIC min = N·FIB min / 2.

[0123] THE Figures 12A et 12B represent respectively the curves of RS max (N=1) = FSC max (N=1) / F0c and of RS max (N=2) = FSC max (N=2) / F0c as a function of the amplitude θ 0 of the free oscillation of the mechanical resonator for various quality factors Q of this mechanical resonator. It is observed that the smaller the quality factor, the larger the ratio RS max (N).

[0124] There Figure 13A gives, for a resonator having a quality factor Q = 100, a free amplitude θ 0 = 300° and a safety angle θ Sec = 25°, the upper correction frequency ranges, for a set frequency F0c and various respective values ​​of N, which are possible within the framework of the first mode of correction of a delay, by representing the ratio RS = FS C or / F0c which extends between the value '1' and RS max (N).

[0125] There Figure 13B gives, for a resonator having a quality factor Q = 100, a free amplitude θ 0 = 300° and a safety angle θ Sec = 25°, the lower correction frequency ranges, for a set frequency F0c and various respective values ​​of N, which are possible within the framework of the first mode of correction of an advance, by representing the ratio RI = FI Cor / F0c which extends between RI max (N) and the value '1'.

[0126] As previously stated, the ranges given to the Figures 13A et 13B derive from a simplified theoretical model. We see that the maximum and minimum correction frequencies depend on several parameters. These figures give a good indication of reality for a mechanical movement with fairly standard properties. However, for each given mechanical movement, it will be necessary to define the limit values ​​if we wish to approach them in order to make large corrections in relatively short correction periods.

[0127] After having explained in detail the arrangement of the control unit and the operation of the correction device of the first embodiment of the timepiece according to the invention for correcting a delay in the time displayed by the timepiece, the arrangement of the control unit according to this first embodiment will be explained below for correcting an advance in the time displayed according to a second mode of correction of an advance.

[0128] To enable the implementation of the second mode of correction of an advance, the timepiece comprises a device for blocking the mechanical resonator. Generally, in the context of the second mode of correction of an advance, the control unit is arranged to be able to provide the blocking device, when the external correction signal received by the receiving unit corresponds to an advance in the displayed time that is intended to be corrected, a control signal which activates the blocking device so that this blocking device blocks the oscillation of the mechanical resonator during a correction period whose value / duration is determined by the advance to be corrected, so as to stop the operation of said drive mechanism during this correction period.

[0129] In the first embodiment described with reference to the Figures 1 And 7, the timepiece 2 comprises a blocking device which is constituted by the braking device 22, in particular by the piezoelectric actuator 22A, which also serves to implement the first mode of correction of a delay. When the overall time error T Err corresponds to an advance in the displayed time which is intended to be corrected, the logic circuit 60 of the control unit 48A ( Figure 7 ) provides a control signal SA to the time counter 70 (timer) which is programmable. This timer 70 then generates a signal S C2 for activating the braking device 22, via the 'OR' gate 66 or another switch, for a correction period PA Cor whose duration is substantially equal to the corresponding advance T Err to be corrected. The periodic activation signal S C2 then forms the control signal S Cmd . It will be noted that the activation signal S C2 controls the braking device 22 in a mode of blocking the mechanical resonator for a relatively long duration, namely for substantially the entire correction period PA Cor = T Err . For this purpose, the voltage then supplied by the power supply circuit 26 between the two electrodes of the piezoelectric blade 24 may differ from that intended to generate the periodic braking pulses to correct a delay.This voltage is selected so that the braking force applied to the mechanical resonator can stop it, preferably fairly quickly, and then block it until the end of the correction period.

[0130] In a variant, the electrical voltage applied to the piezoelectric blade 24 is provided to be variable during the correction period. For example, it is possible to provide a higher voltage at the start of the correction period, which is selected to quickly stop the resonator, in particular during the alternation of the oscillation of this resonator in which the start of the correction period occurs, and then to reduce the voltage to a lower value but sufficient to keep the resonator stopped. Advantageously, the electrical voltage will be selected so that the resulting braking force cannot stop the mechanical resonator in the forbidden angular zone (-θ ZI to θ ZI ) defined previously.For this purpose, the braking torque is selected large enough to be able to stop the resonator and lock it in the angular stopping position, whatever it may be, and small enough so that this braking torque cannot stop the resonator in the forbidden angular zone. Preferably, stopping the resonator in the safety angular zone (-θ Sec to θ Sec ), described previously, will be avoided. This last condition is important when the resonator is not self-starting. Generally speaking, it is sufficient to ensure that the resonator can restart at the end of the correction period.

[0131] According to a specific variant making it possible to ensure a rapid stopping of the resonator outside the aforementioned safety angular zone, a preliminary phase is provided occurring before the correction period where the resonator is blocked (i.e. where it remains stopped following its stopping occurring quickly or immediately at the start of the correction period). During the preliminary phase, it is provided to use the first mode of correction of a delay available in the first embodiment. It can be seen that in the synchronous phase of the first correction mode described above, the passage through an extreme angular position occurs during each braking pulse. Thus, the braking pulses are in phase with passages of the mechanical resonator through one of its two extreme angular positions, each of these passages defining the start of an alternation.Advantage is taken of this fact by activating the frequency generator 62 during the preliminary phase, which is planned to be relatively short in duration but nevertheless of sufficient duration to establish a synchronous phase where the resonator is synchronized to the frequency FS Cor . The preliminary phase ends for example during a last braking pulse which is immediately followed by the correction period with an activation of the braking device in the blocking mode. Thus, it is known that the resonator is blocked outside the safety angular zone. The braking torque for the preliminary phase can be planned different from that used for the correction of a delay explained previously.

[0132] Since the frequency behavior during the transient phase at the beginning of a series of periodic braking pulses can vary from case to case, it is hardly possible to determine the error generated by the preliminary phase. However, it is possible to estimate a maximum error. For example, if the frequency F SUP = 1.05·F0c (correction of 30 seconds in 10 minutes) and the preliminary phase is planned with a duration of 10 seconds (selected duration greater than those of transient phases that may occur), the maximum error can be estimated at 0.5 seconds (half a second). For a mechanical movement, although such an error is not negligible, it is relatively small since a conventional mechanical movement has a daily error generally between 0 and 5 to 10 seconds.

[0133] In reference to the Figure 14 ,a second embodiment of a timepiece according to the invention will be described which is distinguished from the first embodiment by the arrangement of the blocking device making it possible to advantageously implement the second mode of correction of an advance in the time display associated with the mechanical movement of the timepiece. This mechanical movement 92 comprises a conventional escapement 94 formed by an anchor wheel 95 and an anchor 96 which can oscillate between two pins 95. The anchor comprises a fork 97 between the horns of which is conventionally inserted at each alternation the pin 98 also forming the escapement and carried by a plate 100 which is integral with the shaft 102 of the balance 104 (partially shown) of the mechanical resonator or made of the same material as this shaft (that is to say that the shaft is machined with a longitudinal profile defining the plate).The plate 100 is circular and centered on the central axis of the shaft 102 which defines the axis of rotation of the balance wheel 104.

[0134] The timepiece includes a locking device 106 which is separate from the braking device 22A ( Figure 1 ) used for the correction of a delay. This blocking device is therefore dedicated to the implementation of the second mode of correction of an advance. The blocking device is formed by an electromechanical actuator, in particular by a piezoelectric actuator of the same type described in connection with the Figure 1 . According to the variant shown, the actuator comprises a flexible piezoelectric blade 24A and its two electrodes are supplied with voltage by a power supply circuit 26A. The blade 24A has at its free end a projecting part 107, forming a stud, which is located on the side of the plate 100. The blade extends in a direction parallel to a tangent of the circumference of the plate, at a short distance from this circular circumference. The plate has a through hollow 108, which opens radially on the periphery of the plate and whose profile in the general plane of the plate is provided to allow the stud 107 to be housed there when it is located angularly opposite this hollow and the piezoelectric actuator 106 is activated.According to the variant shown, the hollow 108 is diametrically opposite the pin 98 and the stud is located angularly at the zero position of the pin (i.e. at the angular position of this pin when the resonator is at rest, respectively passes through its neutral position). Note that this zero angular position of the pin normally defines the zero angular position of the balance 104, and therefore of the mechanical resonator, in an angular reference frame fixed relative to the mechanical movement 92 and centered on the axis of rotation of the balance.

[0135] In an equivalent variant, the hollow may be arranged at another angle relative to the pin, for example at 90°, and the actuator 106 is then positioned at the periphery of the plate so that the stud 107 is diametrically opposite the hollow when the resonator is at rest. Thus, whatever the alternation and the angular position when the piezoelectric actuator is activated, the stud will enter the hollow when the resonator is in an equal angular position, in absolute value, substantially at 180° (this being exactly the case if the balance is set to the reference mark, that is to say that the pin is aligned with the respective centers of rotation of the balance and the anchor when the resonator is at rest).This value of 180° is clearly outside the safety zone (it is greater than the safety angle defined previously) and it is generally lower than the range of amplitudes of the mechanical resonator corresponding to its useful operating range.

[0136] Then, according to the advantageous variant represented in the Figure 14 , the side walls of the hollow 108 are parallel to the radius passing through its center and the axis of rotation of the balance. In an equivalent variant, these side walls are provided radial. Similarly, the stud 107 has two side walls, perpendicular to the general plane of the plate, which are parallel to the radius passing through its center and the axis of rotation of the balance or which are, in the equivalent variant, substantially radial relative to the axis of rotation. Thanks to this arrangement, when the stud 107 is introduced into the hollow 108 which then serves as its housing, this stud blocks the rotation of the plate 100 and therefore of the balance 104 by a substantially tangential force whose direction is substantially parallel to the general longitudinal direction of the piezoelectric blade 24A.When the actuator 106 is activated, the end of the blade carrying the stud 107 undergoes a substantially radial displacement, relative to the axis of rotation of the balance, and the stud can then, depending on the angular position of the balance at that moment, either exert an essentially radial force on the circular lateral surface of the plate 100, or enter at least partially into the hollow 108. The actuator only needs to be arranged so that the stud can undergo, when this actuator is activated, a sufficient displacement to enter the hollow when the latter is located in an angular position corresponding substantially to that of the stud (in a fixed angular reference frame relative to the stud).

[0137] A relatively low friction force can be expected when the stud comes to bear against the circular lateral surface of the plate at the start of a correction period, i.e. following activation of the actuator, in the case where the hollow is not opposite the stud when its proximal surface reaches the level of the circular circumference of the plate. Thus, it can be ensured that the amplitude of the resonator decreases little during the initial braking effected by the stud exerting a radial force against this circular lateral surface. Then, when the stud is inserted into the hollow while the latter is opposite the stud, the radial force exerted by the piezoelectric blade on the plate can be very low, or even zero. The electrical energy required to block the resonator during the correction period can therefore be relatively small, much smaller than in the case of the first embodiment.

[0138] When the correction device of the timepiece determines during a correction cycle an overall time error corresponding to an advance in the time display, its logic control circuit, in a manner similar to the operation of the first embodiment, activates the blocking device 106, by providing it with a control signal S C2 similar to that described previously in the context of the first embodiment, for a period substantially equal to the overall time error to be corrected.By means of the arrangement of a hollow in a circular plate centered on the axis of rotation of the resonator and an actuator having a corresponding part, but preferably less wide than the hollow, which is arranged to be able to undergo a substantially radial movement between a non-interaction position, corresponding to a non-powered state of the actuator, and a state of interaction with the balance of the resonator, corresponding to a powered state of the actuator in the variant described here, the start of the activation of the blocking device 106 can take place at any time, whatever the angular position of the resonator and whatever the direction of the oscillation movement (therefore independently of the alternation in progress among the two alternations forming each oscillation period). This is very advantageous.

[0139] Finally, in connection with the second embodiment, the electromechanical actuator may be of a type other than that shown in Figure 10 . For example, in one variant, the actuator may comprise a ferromagnetic or magnetized core which can be moved under the action of a magnetic field generated by a coil. In particular, this core is collinear with the coil and it comprises an end portion emerging from the coil at least when the actuator is activated, this end portion forming a finger which is configured to be able to be introduced into the hollow of the plate, this finger having in particular an end portion with the shape of the pad 107. In a preferred variant, the actuator is a bistable actuator. The power supply to the actuator is advantageously maintained, during its activation to move from the non-interaction position to the interaction position, until the pad has entered at least partially into the hollow 108.Such a variant is particularly interesting because the actuator does not have to exert any blocking force by applying radial pressure to an element of the resonator balance in its two stable positions corresponding respectively to the intended non-interaction position and the interaction position. In this preferred variant, the energy consumption can be very low, regardless of the duration of the correction period, which is very advantageous.

[0140] In reference to the Figure 15 , a third embodiment of a timepiece according to the invention will be described, which is essentially distinguished from the first embodiment by the arrangement of the blocking device making it possible to advantageously implement the second mode of correcting an advance in the time display associated with the mechanical movement of the timepiece. The references already described in relation to the Figures 1 And7will not be described again in detail. As in the second embodiment, the timepiece 112 according to the third embodiment comprises a blocking device 114 which is distinct from the braking device 22B used for correcting a delay. The braking device 22B has an operation which is similar to the braking device 22A already described, that is to say it is also suitable for implementing the first mode of correcting a delay explained in detail previously. In the variant described here, the braking device 22B is formed by an electromechanical actuator of the electromagnetic type, that is to say comprising a magnet-coil system for actuating a flexible blade 240 embedded in a support 242 and the free end of which forms a braking element / shoe for the resonator 14.This actuator comprises a magnet 244, carried by the flexible blade, and a coil 246 located opposite the magnet and connected to a power supply 26B which receives the control signal S C1 , which generates electric current pulses in the coil to generate braking pulses. Each current pulse in the coil generates a magnetic flux which generates a magnetic repulsion force on the magnet 244, and the flexible blade 240 then comes into contact with the lateral surface of the rim 20 of the resonator to generate a certain mechanical braking force on this resonator during a braking pulse.

[0141] The locking device 114 is remarkable for at least two reasons. First, it acts on a conventional mechanical resonator 14 requiring no modification, in particular no specific machining unlike the second embodiment. Then, the locking device is a bistable device, that is to say that a locking element has two stable positions, namely here the lever 115. The locking device is arranged in such a way that a first of the two stable positions of the lever corresponds to a position of non-interaction with the balance 16 while the second of these two stable positions corresponds to a position of locking of the resonator via a radial force exerted by a blade 116, forming the lever 115, on the rim 20 of the balance.The blade 116 is pivoted around an axis arranged in the mechanical movement 4A (in another variant, the lever is arranged so that its pivot axis is arranged on a support separate from the mechanical movement and belonging to a correction module). In one variant, this axis is formed by a fixed pin around which an annular end portion of the blade 116 is mounted. This blade is rigid or semi-rigid, a slight flexibility being able to be advantageous.

[0142] The blade 116 is associated with a particular magnetic system making it possible to generate the bistable character of the rocker 115 and consequently of the locking device 114. The magnetic system comprises a first magnet 118, carried by the blade and therefore integral in rotation with this blade, a second magnet 119 arranged fixedly relative to the mechanical movement (in the variant shown, the second magnet is inserted fixedly in a lateral opening of the support 242) and a ferromagnetic plate 120 arranged between the first magnet and the second magnet, at a short distance from the second magnet 119 or against it (for example the plate is glued against this magnet, only a layer of glue then separating the magnet from the plate, or it is inserted fixedly in a housing of the support 242 located in front of the magnet 119).

[0143] The first and second magnets 118, 119 have magnetic polarities that are opposite and their respective magnetic axes are substantially aligned. Thus, in the absence of the ferromagnetic plate, these two magnets would constantly exert a repulsive force on each other and the rocker would always remain or return, in the absence of forces external to the magnetic system, to a position where the blade is in abutment against a pin 124 limiting its rotation. However, thanks to the arrangement of the ferromagnetic plate, there is a reversal of the magnetic force exerted between the two magnets. More precisely, when the movable magnet 118 is approached from its remote position (shown in Figure 11 ), the repulsive force decreases until it is cancelled and finally reverses when the moving magnet comes close to the ferromagnetic plate. Thus, when the moving magnet 118 is located very close to or against the ferromagnetic plate 120, this moving magnet experiences a magnetic force of attraction. This astonishing physical phenomenon is explained in detail in patent application CH 711889, which also contains some watchmaking applications.

[0144] The lever 115 is arranged so as to have two stable positions in the absence of forces external to the magnetic system of the locking device. The first stable position is a non-interaction position in which the blade 116 is in abutment against the pin 124, the movable magnet 118 then undergoing a magnetic repulsion force from the magnetic assembly, formed by the fixed magnet 119 and the ferromagnetic plate 120, which holds the lever 115 against this pin. The second stable position is an interaction position in which the blade 116 is in abutment against the rim 20 of the balance 16, the movable magnet 118 then undergoing a magnetic attraction force from said magnetic assembly which holds the lever 115 against this rim.The ferromagnetic plate 120 is arranged so that the blade 116 exerts a radial blocking force on the balance 16, and therefore on the resonator 14, when the rocker is in its second stable position. In order for the blade to be able to exert a blocking force against the outer lateral surface of the felloe 20, the surface of the plate 120, located opposite the moving magnet 118, must be slightly set back relative to the proximal surface of this moving magnet when the blade 116 comes into contact with the felloe. If the blade is semi-rigid and therefore has a certain flexibility, it is possible that the moving magnet finally comes into abutment against the proximal surface of the ferromagnetic plate, but then the blade is in flexion.

[0145] To move the bistable flip-flop 115 between its two stable positions, in both directions, the blocking device comprises a device for actuating this flip-flop arranged to alternately switch the flip-flop between its two stable positions. In the variant shown, the actuating device is formed by a coil 252 connected to a power supply 254. The coil 252 is aligned with the magnetic assembly, formed by the fixed magnet 119 and the ferromagnetic plate 120, and arranged just behind the movable magnet 118 when the flip-flop is in its non-interaction position. Depending on the polarity of the electrical voltage applied to the coil 252, the movable magnet undergoes a magnetic attraction or repulsion force from this coil, thus making it possible to move the flip-flop from one of its two stable positions to the other in both directions.The actuating device is controlled by the logic circuit of the control unit via its power supply circuit 254 which receives the control signal S C2 . At the beginning of a correction period of an advance, the control signal generates a first pulse of electric current in the coil 252 with a polarity which generates a repulsive force for the moving magnet 118 and a duration sufficient for the rocker to move into its interaction position, then the power supply to the coil is cut off until the end of the correction period where a second pulse of electric current is generated in the coil with an opposite polarity, this second pulse then generating an attractive force on the moving magnet which is provided to be sufficient to switch the rocker to its non-interaction position, thus ending the correction period.

[0146] In another variant, the actuating device of the rocker is provided separate and independent from the magnetic system of the bistable rocker. In this case, the electromagnetic system of the actuating device is formed by a second magnet carried by the rocker and a coil arranged opposite this second magnet, as in the previous variant. This electromagnetic system can be arranged upstream or downstream of said magnetic system relative to the pivot axis of the rocker.

[0147] What is remarkable in this embodiment is the fact that the blocking force exerted by the blocking device during the correction period does not come from an electrical supply of this blocking device, but from said magnetic system which forms it. Thus, the blocking device requires electrical power only at the beginning and at the end of the correction period occurring in the second mode of correction of an advance, when the bistable flip-flop is switched between its two stable states by the actuating device.

[0148] In another variant leading to the same physical phenomenon and therefore to the same desired effect, the ferromagnetic plate 120 is arranged against the moving magnet 118, to which it is integral. Finally, in another variant, it is planned to combine the second and third embodiments. To do this, the blade of the rocker comprises, in the region of contact with the felloe 20, a stud which projects towards this felloe, which has a hollow along its generally circular circumference.The person skilled in the art will know how to arrange the locking device so that its first stable position is a non-interaction position and its second stable position is an interaction position in which the stud is at least partially inserted into the hollow, this stud generally initially exerting dynamic dry friction against the outer lateral surface of the rim, when the lever is actuated by the actuating device to move from its first stable position to its second stable position at the start of a period of correction of an advance, before entering the hollow when the latter is presented opposite the stud during the oscillation of the balance.

[0149] In reference to the Figure 16 and the Figure 1 , a fourth embodiment of a timepiece will be described below. This fourth embodiment is a preferred embodiment which differs from the first embodiment substantially by its method of correcting an advance.

[0150] The power supply 130 of the correction device 132 comprises an energy harvester formed by a solar cell 54A, in particular arranged at the level of the dial or the bezel carrying the glass protecting the dial. This dial generally forms a part of the time display. In addition, an external control device 136 is provided to be able to provide an activation signal on request to the correction device, by a user of the timepiece, to trigger / start in the timepiece a cycle of correction of the displayed time (in other words to launch the method of correction of the displayed time which is implemented in the correction device 132).

[0151] The power supply 130 comprises a circuit 134 for managing the power supply of the correction device 132. This circuit is capable of receiving various information from the electricity accumulator 56 and it receives from the external control device 136 a wake-up signal S W-UP when this device is actuated by a user. Once the management circuit 134 has received a wake-up signal, it detects the level of energy available in the accumulator 56. As in the first embodiment, if the energy level is insufficient to complete the correction process, the management circuit can react in various ways.In particular, it can either remain on standby for an electrical energy supply via its solar cell or another additional energy recovery means, or start a correction cycle as far as possible while knowing that it risks not being able to complete it correctly due to a lack of available energy. In a variant, if the energy level is insufficient to carry out a complete correction cycle but sufficient to carry out a detection phase, the correction device already directly carries out such a detection phase by only supplying power to the parts necessary for this detection phase, while waiting for a new supply of electrical energy to be able to then carry out a correction phase. Generally, when the available energy level is sufficient for a correction cycle, the management circuit 134 activates the correction device to carry out a correction cycle.

[0152] Since the fourth embodiment is characterized by an implementation of the first mode of correction of a delay, as in the first embodiment, and of the first mode of correction of an advance, already described previously but not implemented in the first embodiment, any correction provided here is carried out by a series of periodic braking pulses during a correction period. In a main variant, all the braking pulses are provided with the same duration Tp. Thus, only one and the same timer 64 is necessary to determine the duration of the braking pulses and this timer is arranged, in the variant shown in Figure 16 , in the power supply circuit 26C. This timer provides an activation / actuation signal S Act to a switch 138 placed between a voltage source 140 and the braking member 24C acting on the balance. The braking member 24C is for example similar to the piezoelectric blade ( Figure 1 ) of the variant shown for the first embodiment or to the flexible blade associated with the magnet-coil system ( Figure 15 ) of the third embodiment. Thus, the switch 138 controls the power supply to the actuator forming the braking device. The timer 64 receives a first control signal S1 Cmd from a switching device 66A which is controlled by the logic circuit 60A so that the first control signal is selectively formed by a periodic digital signal from three periodic digital signals provided S FS , S FI and S F0c which respectively have three different frequencies F SUP , F INF and F0c. The periodic digital signal periodically resets the timer to the selected frequency and, in response, this timer periodically activates the actuator for a duration Tp, by momentarily making the switch 138 conductive, to generate a series of periodic braking pulses at this selected frequency.

[0153] When an overall time error determined by the correction device corresponds to a delay to be corrected, the logic circuit 60A determines, as a function of the selected frequency F SUP, a corresponding correction period PR Cor or, equivalently, a number of periodic braking pulses to be generated at the frequency F SUP during the current correction cycle. To do this, it uses the formula relating to this determination which was established previously. To apply the series of braking pulses at the frequency F SUP leading to a correction frequency FS Cor higher than the set frequency, it uses the frequency generator 62, already described, which supplies a periodic digital signal S FS at the frequency F SUP to the timer 64 via the switch 66A, which is controlled for this purpose by the control logic circuit.

[0154] When an overall time error determined by the correction device corresponds to an advance to be corrected, the logic circuit 60A determines, as a function of the selected frequency F INF, a corresponding correction period PA Cor or a number of periodic braking pulses to be generated at a frequency F INF , previously defined, during the current correction cycle. To do this, it uses the formula relating to this calculation which was established previously. To apply the series of braking pulses at the frequency F INF leading to a correction frequency FI Cor lower than the set frequency, it uses the frequency generator 142 which supplies a periodic digital signal S FI at the frequency F INF to the timer 64 via the switch 66A, which is controlled for this purpose by the control logic circuit.

[0155] Generally, to enable the implementation of the first mode of correction of an advance, the electronic control unit 48B is arranged to be able to supply to the braking device, when the correction signal S Cor supplied by the processing unit corresponds to an advance in the displayed time which it is intended to correct, a control signal derived from a periodic digital signal supplied by a frequency generator at a frequency F INF , during a correction period, to activate the braking device so that it generates a series of periodic braking pulses applied to the mechanical resonator at the frequency F INF .This frequency F INF is provided and the braking device is arranged in such a way that the series of periodic braking pulses at the frequency F INF can generate, during the correction period, a synchronous phase in which the oscillation of the mechanical resonator is synchronized to a correction frequency FI Cor which is lower than the set frequency F0c provided for the mechanical resonator. The (duration of the) correction period and therefore the number of periodic braking pulses in said series of periodic braking pulses are determined by the advance to be corrected.

[0156] The correction device of the fourth embodiment comprises an improvement to increase the precision of the correction carried out and also to allow the application of relatively high braking torques, in particular for corrections at frequencies relatively far from the set frequency, without risking the mechanical resonator being permanently stopped by a stop, during a braking pulse at the start of the correction period, in the angular coupling zone between the resonator and the escapement or more generally in the safety angular zone described above.According to this improvement, the timepiece comprises a device for determining the passage of the oscillating mechanical resonator through at least one specific position, this device for determining a specific position of the mechanical resonator allowing the electronic control unit to determine a specific instant at which the oscillating mechanical resonator is in said specific position, and therefore to determine the phase of the resonator. Then, the electronic control unit is arranged so that a first activation of the braking device occurring at the start of the correction period, to generate a first interaction between this braking device and the mechanical resonator, is triggered as a function of said specific instant.

[0157] According to an advantageous variant of the improvement set out above and with reference to the Figure 16 , the correction device further comprises a frequency generator 144 which is arranged to be able to generate a periodic digital signal S F0c at the set frequency F0c provided for the resonator. The control unit 48B is arranged to be able to supply the braking device with a control signal derived from the periodic digital signal S F0c , during a preliminary period directly preceding the correction period, to activate the braking device in such a way that this braking device generates a preliminary series of periodic braking pulses which are applied to the mechanical resonator at the set frequency F0c. To do this, the control logic circuit 60A supplies the generator 144 with a control signal S PP .The duration Tp of the periodic braking pulses and the braking force applied to the oscillating resonator, during the preliminary series of periodic braking pulses, are provided in such a way that none of these braking pulses can stop the oscillating resonator in the coupling zone of this oscillating resonator with the escapement associated with it (between - θ ZI and θ ZI ) or, preferably, in a predefined safety zone (between -θ Sec and θ Sec ) encompassing the coupling zone (these zones have been explained previously).

[0158] Then, the duration of the preliminary period and the braking force applied to the oscillating resonator, during the preliminary series of periodic braking pulses, are provided so as to generate at least at the end of the preliminary period a preliminary synchronous phase in which the oscillation of the mechanical resonator is synchronized (on average) on the set frequency F0c. In the variant shown, the electrical voltage source 140 is variable and controlled by the logic circuit 60A which provides it with a control signal S2 Cmd , so that the voltage level applied to the braking member 24C can be varied to vary the braking force. It is thus possible to provide a lower braking force during the preliminary period than during a correction period which follows it. It is also possible to vary the braking force during the preliminary period and / or the correction period.In a variant, the braking frequency during the preliminary period is equal to 2·F0c; which also leads to synchronization on the frequency F0c by applying an alternating braking pulse.

[0159] The correction period, intended to correct an advance or a delay, directly follows the preliminary period. More precisely, the triggering of a first braking pulse at the frequency F INF or F SUP , at the start of a correction period of the displayed time, occurs after a time interval determined relative to an instant at which the last braking pulse of the preliminary period is triggered, so that this first braking pulse occurs outside a predefined safety zone encompassing the aforementioned coupling zone. This condition is easily fulfilled by the fact that the resonator is in a synchronous phase at least at the end of the preliminary period; which has the consequence that the resonator stops during the last braking pulse of this preliminary period.Thus, a reversal of the direction of rotation occurs during said last braking pulse, so that the start of a new alternation of the oscillation of the resonator occurs during this last braking pulse. The correction device can thus know, with an accuracy of Tp / 2 (for example an accuracy of 3 ms), the phase of the oscillation. Consequently, the electronic control unit can be arranged so that the control logic circuit can determine an initial time for triggering the first braking pulse which meets the above-mentioned condition, by activating the frequency generator 62 or 142, depending on the correction required, after a determined time interval since said last braking pulse which ensures that the first braking pulse is outside the predefined safety zone.

[0160] Furthermore, the instant of triggering of said first braking pulse and the braking force applied to the oscillating resonator, during this first pulse and then during the periodic braking pulses which follow during the correction period, are provided in such a way that the synchronous phase at the correction frequency FI Cor or FS Cor preferably begins from the first braking pulse, or from a second braking pulse if the first braking pulse serves to reduce the amplitude of the oscillation without managing to stop the resonator, and that this synchronous phase remains throughout the correction period. In a particular variant, the first braking pulse of the correction period occurs after a time interval corresponding to the inverse of the frequency F SUP or F INF , depending on the correction required, following the instant at which the last braking pulse of the preliminary period occurs.In another particular variant, said time interval is selected equal to the inverse of twice the correction frequency FS Cor or FI Cor , depending on the correction required, or to the inverse of this frequency FScor or FI Cor . The improvement described above is remarkable because it uses available resources, in particular the braking device provided to carry out the required correction, to determine the phase of the oscillation of the resonator. No sensor specific to the determination of this phase is necessary. In addition, no significant time drift is induced by the preliminary period (generally at most T0c / 4). It will be noted that the generators at the various frequencies have been represented separately in the . Figure 12 , but only one programmable frequency generating device can be used.

[0161] In reference to the Figures 17 à 19 ,A fifth embodiment of a timepiece according to the invention will be described below. This fifth embodiment is arranged to allow the implementation of the second mode of correction of an advance, already described in previous embodiments, and a second mode of correction of a delay which will be described here in detail.

[0162] The timepiece 170 according to the fifth embodiment is partially shown in Figure 17 , where only the mechanical resonator 14A of the mechanical movement is shown. Apart from the device for correcting the displayed time, the other elements of the timepiece are similar to those shown in the Figure 1 . The mechanical resonator comprises a balance 16A associated with a balance spring 15. The balance comprises a rim 20A which has a projecting portion 190 rising radially at its periphery. No other element of the balance rises to the radial position of the end portion of the projecting portion 190.

[0163] The balance wheel comprises a mark 191 formed by a non-symmetrical succession of bars having different reflection coefficients of the light coming from an optical sensor 192 or simply a different reflection of this light, in particular a succession of at least two black bars of different widths and separated by a white bar, the width of one of the two black bars being equal to the sum of the widths of the other black bar with the white bar. It is understood that the bars thus form a sort of code with a transition in the middle of the mark 191. Instead of black bars and a white bar, other colors can be used. In a variant, the black bars correspond to matte areas of the serge, while the white bar corresponds to a polished area of ​​this serge. The black bars can also correspond to notches in the serge which have an inclined plane.Several variants are therefore possible. It will be noted that the mark 191 has been shown on the top of the rim for its description, but in the variant shown it is located on the outer lateral surface of the rim since the optical sensor is arranged in the general plane of the balance 16A. In another variant, the mark is located as shown, on the upper or lower surface of the rim, and the sensor is then rotated 90° to be able to illuminate this mark.

[0164] The optical sensor 192 is arranged to detect the passages of the oscillating resonator through its neutral position (corresponding to the angular position '0' for the projecting part 190) and to make it possible to determine the direction of movement of the balance during each passage through this neutral position. This optical sensor comprises an emitter 193 of a light beam in the direction of the rim 20A, this emitter being arranged so that it illuminates the mark 191 when the resonator passes through its neutral position, and a light receiver 194 arranged to receive at least a portion of the light beam which is reflected by the rim at the mark.The optical sensor thus forms a device for detecting a specific angular position of the balance, enabling the electronic control unit to determine a specific instant at which the oscillating mechanical resonator is in the specific angular position, and also a device for determining the direction of movement of the balance when the oscillating resonator passes through the specific angular position. Other types of position and direction of movement detectors of the mechanical resonator may be provided in other variants, in particular capacitive, magnetic or inductive detectors.

[0165] Then, the timepiece 170 comprises a resonator braking device which is formed by an electromechanical device 174 with a bistable movable stop. An alternative embodiment, by way of non-limiting example, is shown in Figure 17 . The electromechanical device 174 comprises an electromechanical motor 176, of the small clockwork stepper motor type, which is powered by a power supply circuit 178, which comprises a control circuit arranged to generate, when it receives a control signal S4 Cmd, a series of three electrical pulses which are supplied to the coil of the motor so that its rotor 177 advances by one step with each electrical pulse, i.e. by half a rotational revolution. The series of three electrical pulses is intended to drive the rotor rapidly, continuously or almost continuously. The rotor pinion meshes with an intermediate wheel 180 which meshes with a wheel having a diameter equal to three times that of the rotor pinion and fixedly carrying a first bipolar permanent magnet 182. Given the diameter ratio between said pinion and the wheel carrying the magnet 182, the latter rotates half a turn during a series of three electrical pulses.Thus the first magnet has a first rest position and a second rest position in which the first magnet has a magnetic polarity opposite to that of the first rest position (by 'rest position' is meant a position in which the magnet 182 is located after the motor 176 has carried out on command a series of three electrical pulses and its rotor has then stopped rotating).

[0166] In addition, the actuator 174 comprises a bistable rocker 184 pivoted about an axis 185 fixed to the mechanical movement and limited in its rotation by two pins 188 and 189. The bistable rocker comprises at its free end, forming the head of this rocker, a second bipolar permanent magnet 186 which is movable and substantially aligned with the first magnet 182, the magnetic axes of these two magnets being provided to be substantially collinear when the first magnet is in one or the other of its two rest positions. Thus, the first rest position of the first magnet corresponds, relative to the second magnet 186, to a position of magnetic attraction, and its second rest position corresponds to a position of magnetic repulsion.Each time the control signal S4 Cmd activates the power supply circuit to carry out a series of three electrical pulses, the first magnet rotates half a turn and the rocker alternately passes from a stable position of non-interaction with the balance of the resonator to a stable position of interaction with this balance in which the rocker 184 then forms a stop for the projecting part 190, which abuts against the head of this rocker when the resonator oscillates and the projecting part reaches the level of this head, regardless of the direction of rotation of the balance during the shock.

[0167] In the non-interaction position, the movable rocker is outside a space swept by the projecting part 190 when the resonator oscillates with an amplitude in its useful operating range. On the other hand, in the interaction position, the movable rocker is located partially in this space swept by the projecting part and thus forms a stop for the resonator. By 'stable position' is meant a position in which the rocker remains in the absence of a power supply to the motor 176 which is used to actuate the rocker between its two stable positions, in both directions. The rocker thus forms a bistable movable stop for the resonator. This rocker therefore forms a retractable stop member for the resonator. The actuator 174 is arranged so that the rocker can remain in the non-interaction position and in the interaction position without maintaining a power supply to the motor 176.

[0168] The stop member in its interaction position and the projecting part define a first angular stop position θ B for the balance of the oscillating resonator which is different from its neutral position, the projecting part abutting against the stop member at this first angular stop position when it arrives from its angular position '0', corresponding to the neutral position of the resonator, during a second half-alternation of a first determined alternation among the two alternations of each oscillation period of the resonator. Then, the angle θ B is provided less than a minimum amplitude of the oscillating mechanical resonator in its useful operating range. In addition, the angle θ B is provided so that the oscillating resonator is stopped by the stop member outside the coupling zone of the oscillating resonator with the escapement of the mechanical movement, which has already been described.The stop member in its interaction position and the projecting portion also define a second angular stop position, close to the first but greater than it, for the balance of the oscillating resonator when the projecting portion arrives from an extreme angular position of the resonator during a first half-alternation of the second alternation among the two alternations of each oscillation period. This second angular stop position is also provided to be less than a minimum amplitude of the oscillating mechanical resonator in its useful operating range.

[0169] It will be noted that the projecting portion 190 may, in another variant, rise axially from the felloe or from one of the arms of the balance and the bistable electromechanical device 174 is then arranged so that the bistable lever exhibits a movement in a plane parallel to the axis of rotation of the balance. In this other variant, the respective magnetization axes of the two magnets 182 and 186 are axial and remain substantially collinear, the magnet 182 then being arranged under the head of the lever. It will be noted that such an arrangement of the bistable electromechanical device may also be provided within the framework of the variant shown with a projecting portion rising radially from the felloe. It will be noted that the projecting part of the resonator can, in another variant, be arranged around the balance shaft, in particular on the periphery of a plate carried by this shaft or made of the same material as the shaft.In one variation, such a plate is the plate carrying the escapement pin.

[0170] Finally, the timepiece 170 comprises a control unit 196 which is associated with the optical sensor 192 and arranged to control the power supply circuit 178 of the electromechanical device, to which the control unit supplies the control signal S4 Cmd. The control unit comprises a control logic circuit 198, a bidirectional time counter 200 and a clock circuit 44. This control unit is associated with the electromechanical device 174 to allow the implementation of the second mode of correcting an advance and also the second mode of correcting a delay in the time indicated by the display of the timepiece, explained below.

[0171] To implement the second correction mode implemented in this fifth embodiment, the control unit 196 is arranged to control the electromechanical device (also called 'actuator' or 'electromechanical actuator') so that it can selectively actuate the stop member (the bistable lever 184), depending on whether it is intended to correct a delay or an advance in the time displayed by the timepiece, so that this stop member is moved from its non-interaction position to its interaction position respectively before the projecting portion 190 reaches said first angular stop position θ B during said second half-alternation of said first alternation of an oscillation period and before the projecting portion 190 reaches said second angular stop position during said first half-alternation of said second alternation of an oscillation period.

[0172] Generally, to correct at least in part an advance (positive time error), the electromechanical device is arranged in such a way that, when the stop member is actuated to stop the mechanical resonator in a first half-wave, the stop member momentarily prevents, after the projecting part has abutted against this stop member, the mechanical resonator from continuing the natural oscillation movement specific to this first half-wave, so that this natural oscillation movement during the first half-wave is momentarily interrupted before it is continued, after a certain blocking time which ends with the withdrawal of the stop member.Preferably, in the case of a bistable electromechanical device as described above, provision is made to correct substantially the entirety of a positive overall time error, determined by the correction device of the timepiece according to the invention, during a continuous blocking period defining a correction period, which is provided to be substantially equal to the advance to be corrected.To do this, in the variant described, following the instant of passage of the resonator through its neutral position during a said second alternation of an oscillation period (alternation where the projecting part 190 arrives at the level of the head of the rocker 184 before the passage of the resonator through its neutral position), this second alternation being detected by the optical sensor 192 thanks to the arrangement provided for detecting the direction of the oscillation movement during the detection of the passages of the resonator through its neutral position, the control unit waits until a delay of T0c / 4 is reached to activate the actuator so that it drives, via its motor, the rocker 184 between its stable non-interaction position to its stable interaction position where the head of the rocker forms a stop for the projecting part.Depending on the value of the stop angular position, for example between 90° and 120°, it is possible to provide a shorter time than T0c / 4, for example T0c / 5, to trigger a series of three electrical pulses to drive the motor 176 so that its rotor rotates quickly by one and a half revolutions, the time interval to allow the rocker to pivot between its two stable positions, by reversing the direction of the magnetic flux generated by the magnet 182, being thus lengthened. In the latter case, it must be ensured that the projecting part has indeed exceeded the stop angular position in the alternation preceding the first half-alternation during which it is intended to block the resonator during a correction period.

[0173] Generally, to correct at least in part a delay (negative time error), the electromechanical device is arranged so that, when the stop member is actuated to stop the mechanical resonator in a second half-alternation of at least one said first alternation of an oscillation period (alternation during which the projecting part 190 arrives at the level of the head of the rocker 184 after the resonator has passed through its neutral position), it thus prematurely ends this second half-alternation without blocking the resonator but by reversing the direction of the oscillation movement of this resonator, so that the mechanical resonator begins, following an instantaneous or almost instantaneous stop caused by the collision of the projecting part with the stop member, directly a following alternation.Thus, in the context of the second mode of correction of a delay, the detector of position and direction of movement of the resonator and the electronic control unit are arranged so as to be able to activate the actuator, each time that the overall time error determined by the correction device corresponds to a delay in the displayed time, so that this actuator actuates its stop member so that the projecting part of the oscillating resonator abuts against this stop member in a plurality of half-alternations of the oscillation of the mechanical resonator which each follow its passage through the neutral position, so as to prematurely put an end to each of these half-alternations without blocking the mechanical resonator. The number of half-alternations of said plurality of half-alternations is determined by the delay to be corrected.

[0174] In a preferred variant shown in Figures 18 et 19 , the electronic control unit and the actuator are arranged in such a way that, in order to correct at least in part a delay, the rocker is maintained in its interaction position, following an actuation of this rocker from its non-interaction position to its interaction position while the oscillating resonator is angularly located on the side of its neutral position relative to the angular stop position, until the end of the correction period during which the projecting part of the oscillating mechanical resonator periodically abuts several times against the head of the rocker, the (duration of the) correction period during which the rocker is maintained in its interaction position being determined by the delay to be corrected.The pivoting of the rocker from its non-interaction position to its interaction position can occur either in a so-called first alternation (the one where the impact with the projecting part is expected, this first alternation being detected by detecting the direction of rotation of the balance) preferably directly after detecting the passage through the neutral position so that the rocker is placed in its interaction position before the projecting part reaches the stop angle θ B, or in a so-called second alternation (also detected by detecting the direction of rotation of the balance) directly after detecting the passage through the neutral position, this second variant leaving more time to actuate the rocker and allow it to be placed stably in its interaction position (the stop angle is by definition less than or equal to 180°).For example, if θ B = 120° and the amplitude of the free oscillation of the resonator θ L = 270°, then in the second variant we have a time interval corresponding to a rotation between the angle '0' and a little less than 240° (360°-120°), or approximately 230° if the angle θ T to the axis of rotation defined by the head of the rocker is approximately 10°, to carry out the pivoting of the rocker (so as not to block the balance by exceeding the position of the projecting part in the second alternation); whereas in the first variant we only have a time interval corresponding to a rotation between the angle '0' and 120°. It will be noted that if θ L < 360°- θ B - θ T , then we have much more time in the second variant to carry out the pivoting of the rocker.

[0175] Generally, to determine the duration of a delay correction period, the control unit comprises a measuring circuit associated with the optical sensor, this measuring circuit comprising a clock circuit, providing a clock signal at a determined frequency, and a comparator circuit making it possible to measure a time drift of the oscillating resonator relative to its set frequency, the measuring circuit being arranged to be able to measure a time interval corresponding to a time drift of the mechanical resonator since the start of the correction period. The control unit is arranged to end the correction period as soon as said time interval is equal to or slightly greater than an overall time error determined by the correction device.

[0176] In the variant described in Figure 17 , the measuring circuit comprises a clock circuit 44, providing a periodic digital signal at the frequency F0c / 2, and a bidirectional counter 200 (reversible counter). This bidirectional counter receives at its '-' input the periodic signal from the clock circuit (generating a decrement of this counter by two units for each setpoint period T0c = 1 / F0c) and at its '+' input a digital signal from the optical sensor 192 which comprises a pulse or a change of logic state at each passage of the resonator 14A through its neutral position '0'. As such a passage occurs in each alternation of the oscillating resonator, the counter 200 is incremented by two units at each oscillation period. Thus the state of the counter (integer number M Cb ) is representative of a time drift of the mechanical resonator relative to the setpoint frequency which is determined by the clock circuit 44 having the precision of a quartz oscillator.The integer M Cb corresponds to the number of additional alternations carried out by the resonator, from an initial instant when the reversible counter is reset, relative to a case of an oscillation at the set frequency.

[0177] The control logic circuit 198 receives from the optical sensor 192 a digital signal allowing this logic circuit to determine the passages of the resonator through its neutral position and the direction of the oscillation movement at each of these passages. To correct a given delay, following detection of a passage of the resonator through its neutral position as described above, the control logic circuit, on the one hand, activates the actuator 174 so that it actuates the flip-flop to its interaction position and, on the other hand, resets (performs a 'reset') the bidirectional counter 200, which defines the start of a correction period. It will be noted that this reset can, in a variant, take place before the actuator 174 is powered to effect the pivoting of the flip-flop, but after the control unit 196 and the optical sensor 192 are activated.In other variants, the optical sensor is replaced by another type of sensor, for example of the magnetic, inductive or capacitive type. In a specific variant, the detector of the passage of the mechanical resonator through its neutral position is formed by a miniaturized sound sensor (MEMS type microphone) capable of detecting the sound pulses generated by the impacts between the balance pin and the anchor fork forming the escapement of the mechanical movement.

[0178] The number of alternations at the set frequency F0c in a negative overall time error T Err (determined delay) is equal to -T Err 2 F0c. Thus, as soon as the number M Cb of the bidirectional counter reaches this value or slightly exceeds it (because this value is not in all cases an integer), the determined delay is made up and the time display is again correct (it then gives the real time accurately, in particular with an accuracy of one second). The logic control circuit is therefore arranged to be able to compare the state of the counter with the value -T Err 2 F0c, and to end the correction period as soon as it detects that the number M Cb is equal to or greater than this value, by controlling the power supply circuit 178 of the actuator so that the latter actuates the flip-flop from its stable interaction position to its stable non-interaction position.

[0179] To Figures 18 et 19 the oscillations of the resonator 14A are represented, respectively in two particular extreme cases of the preferred variant set out previously, at the start of a correction period of a given delay. Figure 18 concerns the case where the kinematic energy of the resonator is entirely absorbed during each impact between the projecting part of the balance and the head of the stop. The free oscillation 210 has in particular a second free alternation A2 L before a detection of a time t 0 at the passage of the resonator through its neutral position (position '0' of the projecting part 190) in the first alternation which follows, the time t 0 marking the start of a correction period of a given delay. The rocker is moved into its interaction position directly after the time t 0 . Following the first impact between the projecting part and the rocker, a relatively large positive phase shift DP1 is obtained between the fictitious free oscillation 211 and the oscillation 212.Then a stable phase is established where the oscillation 212 is shortened, relative to a fictitious free oscillation 213 since the previous stopping of the resonator by the stop member, in the second half-alternation of the first alternation A1 of each oscillation period; which then results in a positive phase shift DP2 smaller than DP1. The second alternation A2 of the oscillation 212 is not disturbed by the rocker.

[0180] There Figure 19 concerns a particular case of a hard shock or elastic shock between the projecting part and the head of the rocker. In this case the kinetic energy of the resonator is conserved at each shock, given that there is no dissipation of kinetic energy during the shocks, but only a reversal of the direction of the oscillation movement. The amplitude of the oscillation 216 during the correction period thus remains identical to that of the free oscillation 210, and therefore of the fictitious free oscillation 217 for each oscillation period. Following time t 0 a stable phase is established with alternations A1* and A2* of duration T2 much less than T0 / 2, generating a relatively large positive phase shift DP3 at each oscillation period.

[0181] To obtain an elastic shock, it is possible to provide that the rocker has a certain elasticity, in particular that the body of the rocker and / or its head are formed of an elastic material capable of undergoing a certain compression, so as to momentarily absorb the kinetic energy of the balance to restore it immediately after the reversal of the direction of the oscillation movement. In this case, the oscillation 216 will slightly exceed the stop angle θ B . In another more sophisticated variant, it is the projecting part which is mounted elastically on the rim of the balance. For example, the projecting part has a base forming a slide arranged in a circular slide machined in the rim and an elastic element, in particular a small coil spring is arranged in the slide at the rear of the slide, that is to say on the other side of the head of the rocker relative to the projecting part when it is in its angular position '0'.In practice, the shocks between the projecting part of the balance and the stop of the electromechanical device are generally between the two extreme situations described in . Figures 18 et 19 .

[0182] In another embodiment, the electromechanical device is formed by a monostable electromechanical actuator which comprises a movable finger arranged in such a way that this movable finger can be moved alternately between a first radial position and a second radial position when this actuator is respectively not activated (not powered) and activated (i.e. it is powered). The first radial position of the finger corresponds to a position of non-interaction with the balance of the oscillating resonator and its second radial position corresponds to a position of interaction with the oscillating balance in which this finger then forms a stop for the projecting part of the oscillating balance, in a similar manner to the head of the rocker 184.

[0183] In a preferred general variant, the correction device is arranged so as to be activated periodically, automatically, to carry out a correction cycle during which the detection device is activated during a detection phase, so as to allow the electronic correction circuit to determine an overall time error, and the braking device is then activated to correct, during a correction period, at least the major part of this overall time error.

[0184] In a particular embodiment of the present invention, it is intended to exploit the braking device of the correction device and the internal clock circuit not only to correct a time error detected in the display of the real time, but also to implement a regulation as provided in the document WO 2018 / 177779 already cited previously. According to the teaching of this document, a mechanical braking device, of the type described in the context of the present description, is used to impose on the oscillating mechanical resonator an average frequency which is synchronized to a set frequency F0c determined by an internal electronic clock circuit providing a periodic reference signal. To do this, the regulation device continuously and periodically activates the mechanical braking device at a braking frequency derived from the periodic reference signal.By means of such regulation, a time drift of the oscillating mechanical resonator can be effectively prevented as long as the regulation device is active (in particular supplied with electricity). By advantageously combining the regulation device described in WO 2018 / 177779 with the correction device according to the present invention (using the mechanical braking device and the clock circuit in common), the frequency at which the correction device must be activated can be limited, which can surprisingly lead to a reduction in electricity consumption despite the fact that the regulation device is still active.

[0185] Without the regulation device, the correction device is, for example, activated once a week to carry out a correction cycle (with a mechanical watch that is otherwise relatively precise, this can ensure that the error does not exceed one minute). To fully benefit from the correction device and have a watch whose error for the actual time displayed remains lower than the usual daily error (in particular, less than 10 seconds), the correction device is advantageously activated once a day. If one wants to claim precision of the order of a second, correction cycles must then be carried out periodically, for example every three or four hours; which then generates relatively high electricity consumption.On the other hand, with an implementation of the regulation process (which a priori does not require any additional hardware resources), it is possible to automatically activate the correction device only once a month, or even less often, as long as the mechanical movement runs without stopping. However, it should be noted that it is not uncommon for a mechanical watch to be stopped if, for a classic automatic movement, its user does not wear it a few days a week and if, for a manually wound movement, its user does not wind it regularly. In such a case, following a subsequent winding of the barrel, the display must be reset to the correct real time, which is generally done manually by the user.In addition, the watch may be subject to disturbances (for example, shocks or strong accelerations that may cause a hand to slip on its axis, as well as the momentary presence of an intense external magnetic field, etc.). As already indicated, an external intervention (manual time setting via an external control member) may also vary the display. In all these situations, the correction device according to the present invention is necessary to guarantee an accurate display of the real time by the watch. However, if the correction device is controlled by appropriate sensors or detectors so as to be activated following a disturbing or potentially disturbing event, in particular following a manual time setting indicated above, the implementation of the regulation method in a timepiece according to the present invention may prove advantageous.

[0186] In an advantageous embodiment, the timepiece comprises an external control member actuable by a user of the timepiece, this external control member and the correction device being arranged so as to allow a user to activate the correction device so that it performs a correction cycle during which the detection device is activated for a detection phase, so as to determine an overall time error, and the braking device is then activated to correct, during a correction period, at least the major part of this overall time error. In a particular variant, the external control member is formed by a crown associated with a control stem which also serve to manually set the time of the display.In a preferred embodiment, the ability to control the correction device by an external control member to perform a correction cycle is combined with an internal automatic control that periodically activates the correction device to regularly perform a correction cycle.

[0187] In reference to the Figures 20 à 24 ,a second embodiment of the detection device will be described below, which is arranged in a timepiece 260 so as to be able to carry out indirect detection of the passage of at least one indicator of the display through at least one corresponding reference time position. In general, the detection device is arranged to be able to detect at least one respective predetermined angular position of a wheel secured to the indicator in question or of a detection wheel, forming the drive mechanism or complementary to it, which drives or is driven by the wheel secured to the indicator. Where appropriate, the detection wheel is selected or configured so as to have a rotation speed lower than that of the wheel secured to the indicator and a gear ratio R equal to a positive integer or the inverse of an integer depending on whether the detection wheel is respectively driving or driven.The predetermined angular position which is detected by a detection unit of the detection device corresponds to a given reference time position for the indicator considered. Thus, the detection of the time of passage of the wheel integral with the indicator or the detection wheel by said predetermined angular position makes it possible to then determine a time error, as was described previously for the first embodiment of the detection device relating to direct detection.

[0188] To Figures 20 et 21 an advantageous arrangement of an optical detection unit 274 is shown for detecting the passage of the seconds hand 262 through a given reference time position. This detection is carried out indirectly by detecting a specific reference axis AR of the seconds wheel 264 which carries this hand. The seconds wheel is conventionally driven in rotation by a middle wheel 266 via the seconds pinion 265. The seconds wheel 264 is in the example given in direct meshing connection with the escapement wheel which is formed of an escape wheel 268 and a pinion 269. The escape wheel 268 is coupled to the resonator of the mechanical movement in question.

[0189] The detection device comprises an optical detection unit 274 associated with the seconds hand 262 and arranged to be able to detect a predetermined angular position of the seconds wheel. This detection unit is similar to any optical detection unit described in the context of the first embodiment. It will be noted that a detection unit of another type may be provided, in particular of the capacitive, magnetic or inductive type. The reference axis AR, defining said predetermined angular position of the seconds wheel 264, is defined by a specific arm 288 of this wheel which has a width different from that of the other arms 286 of the wheel. This arm 288 has at least one reflective zone in the region scanned by the light beam 232, emitted by the light source, during its passage under the detection unit 274.To keep the wheel balanced, it will be noted that the arm 288 has a reduced thickness because it has approximately double the width of the other arms. The detection unit 274 is arranged on a support 280, in particular a PCB, and inserted into an opening in the plate 272.

[0190] Processing unit 46 ( Figure 1 ) determines the reference axis AR on the basis of a series of measurements at a given measurement frequency F Ms, in a manner similar to the determination of the middle longitudinal axis of the minute hand in the first embodiment of the detection unit, and thus the instant of passage of this middle longitudinal axis below the middle longitudinal axis of the detection unit 274, which comprises a light source 278 and a photosensitive detector 276 aligned in a radial direction of the second wheel. The superposition of the middle longitudinal axes of the specific arm and of the detection unit defines the predetermined reference time position. To use the notation used previously (when describing the operation of the processing unit 46), said superposition of the middle longitudinal axes, during a detection phase, determines the instant of passage T X0 of the second hand by the reference time positionX0. Thus, the watchmaker must angularly position the seconds hand relative to the seconds wheel so that, during said superposition of the middle longitudinal axes, the seconds hand indicates a running second corresponding to the predetermined reference time position.

[0191] To Figures 22 à 24 an advantageous system for detecting the passage of the minute indicator through at least one reference time position of the display of the timepiece 260 is shown. This detection device is formed of an optical detection module 300, comprising two detection units, and a detection wheel which is specifically arranged for the intended detection. Each detection unit is similar to any optical detection unit described in the context of the first embodiment. Again, it will be noted that a detection unit of another type may be provided, in particular of the capacitive, magnetic or inductive type. The minute wheel has a gear ratio R = 1 / 3 with the cannon pinion which drives it. This is therefore a reduction ratio between the driving cannon pinion and the driven minute wheel. Figure 22 is still referenced the barrel 292 which drives the center wheel 290. In another variant, the detection device comprises only one detection unit.

[0192] Since the minute hand 34M is carried by a cannon-pinion 296 which generally has only a central cylinder forming its axis and a small-diameter pinion, the indirect detection of the passage of the minute hand through at least one given reference time position is thus advantageously provided by means of a detection of at least one reference axis, among at least one series of given reference axes which respectively define a series of predetermined periodic angular positions, of the timer wheel 294 which is rotated by the cannon-pinion 296. This timer wheel forms a timer wheel set whose pinion 295 meshes with the hour wheel 298 provided with a cylindrical axis carrying the hour hand 34H. It is arranged in a recess of the plate 272.The plate supports the timer wheel at the top and carries the optical detection module 300 at the bottom, which is therefore arranged below the timer wheel. The plate has two through openings which are provided respectively above the two detection units for the passage of the light beam 232 between each of them and the timer wheel, more precisely the region in which the arms 306, 308 of this timer wheel extend. Each detection unit has a light source 302, 302A and a photosensitive detector 304, 304A. The two optical detection units are arranged on a common support 310 which have two openings 312, 312A respectively aligned with the two detection units.

[0193] In general, the detection device comprises at least one detection unit associated with the minute indicator and arranged to be able to detect at least a first series of R given periodic angular positions of the minute wheel which are defined by a first series of R respective reference axes A1 S1 , A2 S1 and A3 S1 . Two adjacent angular positions of this first series have between them a central angle α equal to 360° / R where R is said gear ratio (α = 360° / 3 = 120° with the gear ratio selected in the described variant). In the described variant, the detection module is further arranged to be able to also detect a second series of R given periodic angular positions of the minute wheel which are defined by a second series of R respective reference axes A1 S2 , A2 S2 and A3 S2 which are different from the reference axes of the first series.Two adjacent angular positions of the second series having between them a central angle of the same value as the angle α, i.e. equal to 360° / R = 120°. Advantageously, if S series of R periodic angular positions are provided, these S series being offset two by two by an angle equal to 360° / (R·S). In the variant shown, this angular offset angle is equal to 360° / 3·2 = α / 2 = 60°.

[0194] Each series of periodic angular positions is associated with a respective plurality of R specific elements or specific recesses of the timer wheel. In the variant shown, this is a plurality of arms of the timer wheel, the first series of reference axes being defined respectively by three arms 306 having a first width and the second series of reference axes being defined respectively by three arms 308 having a second width different from the first width. The detection of each reference axis is carried out in a similar manner to the detection of the reference axis AR and the determination of an instant of passage of the minute hand by any of these reference axes is also carried out in a similar manner to the determination of the instant of passage of the second hand by the reference axis AR.

[0195] In a general variant, the timer wheel is configured so that each angular position of the first series has the same first signature for the correction device, so that the electronic correction circuit can associate a single and same first reference time position with the minute indicator when detecting any angular position / any reference axis of the first series, and so that each angular position of the second series has the same second signature, different from the first signature, for the correction device, so that the electronic correction circuit can associate a single and same second reference time position, different from the first reference time position, with the minute indicator when detecting any angular position / any reference axis of the second series.Thus, the electronic correction circuit can determine a second passage time. T Y0 of the minute indicator by a reference time position Y0 (any of the two reference time positions provided in the described variant) in an unequivocal manner.

[0196] In another general variant, the detection detection device comprises K detection units, K being an integer greater than one, and the number of series of periodic angular positions of the timer wheel is an integer S greater than zero, each series of periodic angular positions being associated with a respective plurality of R specific elements or specific recesses of the timer wheel. The K detection units are arranged to be each able to detect the S pluralities of R specific elements or specific recesses of the timer wheel. Any two of the K detection units are angularly offset by a separation angle whose remainder of the integer division by an angle equal to 360° / (R·S) is different from zero. Preferably, the remainder of the integer division is substantially equal to 360° / (R·S·K). For the variant shown, 360° / (3·2·2) = 360° / 12 = 30° for the preferred remainder.The separation angle β between the two radial detection directions defined by the arrangement of the two detection units has a value β = 90°. The remainder of the integer division of β by an angle of 360° / (R·S) = 360° / (3·2) = 60° gives a value of 30°; which corresponds to the aforementioned preferred case.

[0197] Finally, it will be noted that the number of reference time positions of the 34M minute indicator that can be detected by the correction device with the second embodiment of the detection device is equal to S·K. In the variant shown, this number is equal to 2·2 = 4. These four reference time positions are offset two by two by 15 minutes (corresponding to an angle of 90°); which is equivalent to the advantageous variant shown for the first embodiment of the detection device.

Claims

1. Timepiece (2; 112; 170; 260) comprising: - a display (12) displaying an actual time, which is formed by a set of indicators comprising an indicator relating to a given time unit of the actual time and indicating the corresponding current time unit; - a mechanical movement (4; 4A; 92) comprising a mechanism (10) for driving the display and a mechanical resonator (14; 14A) which is coupled to the drive mechanism such that the oscillation thereof times the running of this drive mechanism; and - a device (6; 132) for correcting the actual time indicated by the display; characterised in that the device for correcting the actual time displayed comprises: - a detection device (30) arranged to allow for the detection, in a direct manner or via a wheel kinematically linked to said display indicator, of the passage of this indicator through at least one reference time position of said display, this reference time position being relative to said time unit of the actual time; - an electronic correction circuit (40); and - a braking device (22; 22A; 22A, 106; 22B, 114; 24C, 26C; 174) of the mechanical resonator; in that the electronic correction circuit comprises: - a control unit (48; 48A; 48B) arranged to control the detection device such that this detection device carries out, during a detection phase, a plurality of successive measurements and provides a plurality of corresponding measurement values, - a processing unit (46) arranged such that it can receive, from the detection device, said plurality of measurement values and process them, and - an internal time base (42) comprising a clock circuit (44) and generating a reference actual time formed at least by a reference current time unit corresponding to said current time unit of the actual time displayed; in that the electronic correction circuit is arranged and the duration of the detection phase is provided to allow the detection device to detect, when the drive mechanism is running and timed by the oscillating mechanical resonator, at least a passage of said indicator through any reference time position from said at least one reference time position; in that the electronic correction circuit is arranged such that it can determine at least one moment at which said indicator passes through said any reference time position on the basis of at least one measurement value from said plurality of measurement values and one corresponding moment of measurement, which is determined by the internal time base and formed by at least a corresponding value of said reference current time unit; in that the electronic correction circuit is further arranged such that it can determine a time error of said indicator, by comparing said at least one moment of passage with said reference time position, and an overall time error (TErr) for said set of indicators of the display as a function of at least said time error of said indicator; and in that the control unit is arranged such that it can also control the braking device as a function of said overall time error, this braking device being arranged such that it can act, during a correction period, on the mechanical resonator, as a function of said overall time error, to vary the running of the drive mechanism of the display so as to correct at least part of this overall time error, in particular most of this overall time error and preferably substantially all of this overall time error.

2. Timepiece according to claim 1, characterised in that the control unit (48; 48A; 48B) and / or the processing unit (46) is / are connected to the internal time base (42) so as to be able to save in memory said reference actual time at at least one given moment of the detection phase; in that the electronic correction circuit (40) is arranged such that it can determine, during the detection phase, at least a first moment of measurement and a second moment of measurement corresponding respectively to at least a first measurement and a second measurement from among said plurality of successive measurements, these first and second moments of measurement being determined by the internal time base, the first moment of measurement being formed by at least a corresponding first value of said reference current time unit and the second moment of measurement being formed by at least a second value of this reference current time unit; and in that the electronic correction circuit is arranged such that it can subsequently calculate, as a function of said at least a first moment of measurement and a second moment of measurement and of the corresponding measurement values, a third moment which determines said moment of passage of said indicator through said reference time position.

3. Timepiece according to claim 1 or 2, wherein said display (12) comprises an hours indicator (34H) giving the current hour, a minutes indicator (34M) giving the current minute and a seconds indicator (34S; 262) giving the current second of the actual time displayed; and wherein said reference actual time generated by the internal time base is formed by at least a reference current second and a reference current minute; characterised in that the detection device (30) is arranged such that it can detect the passage of the seconds indicator through at least a first reference time position of the display and the passage of the minutes indicator through at least a second reference time position of this display; in that the electronic correction circuit (40) is arranged and the duration of the detection phase is provided to allow the detection device to detect, during this detection phase, when said drive mechanism (10) is running and timed by the oscillating mechanical resonator (14), at least a passage of the seconds indicator through any first reference time position from said at least one first reference time position and at least a passage of the minutes indicator through any second reference time position from said at least one second reference time position; in that the electronic correction circuit (40) is arranged such that it can determine, in conjunction with the internal time base (42) and on the basis of measurement values from said plurality of measurement values, at least one first moment of passage of the seconds indicator through said any first reference time position, this first moment of passage being formed at least by a corresponding value of said reference current second, and at least one second moment of passage of the minutes indicator through said any second reference time position, this second moment of passage being formed at least by a corresponding value of said reference current minute; and in that the electronic correction circuit (40) is arranged such that it can determine a first time error for said seconds indicator (34S; 262), by comparing said at least one first moment of passage with said first reference time position, and a second time error for said minutes indicator (34M) by comparing said at least one second moment of passage with said second reference time position; the electronic correction circuit being further arranged such that it can determine said overall time error (TErr) for the display (12) as a function of said first time error and of said second time error.

4. Timepiece according to claim 3, characterised in that at least the minutes indicator, from among said set of indicators, is of the analogue type, this minutes indicator giving the current minute as a positive integer and a fractional part; in that the timepiece further comprises a time-setting device which is arranged to be able to momentarily break the kinematic link between the minutes indicator and the seconds indicator to set manually said display; and in that the electronic correction circuit is arranged such that it can determine said overall time error (TErr) for said display also as a function of at least one predefined correction criterion for the seconds indicator and / or the minutes indicator.

5. Timepiece according to claim 4, characterised in that said overall time error is determined so as to substantially correct the first-time error for the seconds indicator during said correction period.

6. Timepiece according to claim 5, characterised in that said overall time error is determined such that the minutes indicator has, at the end of said correction period, for the case where this minutes indicator thus has a time difference corresponding to a loss, at most a maximum loss which is selected in a range of values of said fractional part of the current minute displayed.

7. Timepiece according to any of the preceding claims, characterised in that, during the detection phase, the detection device (30) is activated so as to carry out said plurality of successive measurements at at least one measurement frequency determined by said clock circuit (44) of the internal time base (42), this clock circuit providing a periodic digital signal at the measurement frequency directly to the detection device or indirectly to this detection device via the control unit (48; 48A; 48B).

8. Timepiece according to claim 7 and on any of claims 3 to 6, characterised in that said measurement frequency is variable; and in that the correction device (6; 132) is arranged such that it can detect the passage of the seconds indicator (34S; 262) through said at least one first reference time position with a first measurement frequency FSMes and the passage of the minutes indicator (34M) through said at least one second reference time position with a second measurement frequency FMMes that is less than the first measurement frequency.

9. Timepiece according to claim 8, characterised in that the first measurement frequency FSMes is provided such that it is less than three times a setpoint frequency for said mechanical resonator and greater than or equal to 1 Hz, i.e. 1Hz <= FSMes < 3·F0c, whereas the second measurement frequency FMMes is provided such that it is less than or equal to 1 / 8 Hz (FMMes <= 1 / 8 Hz).

10. Timepiece according to claim 8 or 9, characterised in that said first measurement frequency FSMes has a value that is different from double the setpoint frequency F0c divided by a positive integer N, i.e. FSMes ≠ 2·F0c / N.

11. Timepiece according to any of claims 1 to 6, characterised in that the device (6; 132) for correcting the actual time displayed comprises a sensor (192) associated with said mechanical resonator (14A) and arranged such that it can detect the passages of the oscillating mechanical resonator through the neutral position thereof, corresponding to the position of minimum potential energy thereof; and in that, during the detection phase, said detection device (30) is activated and controlled by said control unit (48; 48A; 48B) associated with the internal time base (42) to carry out said plurality of successive measurements, each following the detection of a passage of the mechanical resonator through the neutral position thereof and after a certain time difference from this detection.

12. Timepiece according to claim 11, characterised in that said time difference lies in the range T0c / 8 to 3·TOc / 8, where T0c is the setpoint period equal to the inverse of the setpoint frequency.

13. Timepiece according to any of the preceding claims, characterised in that the detection device (30) is arranged in the timepiece such that it can directly detect said passage of said indicator of the display through said at least one reference time position, this indicator being arranged such that it can be detected by the detection device.

14. Timepiece according to claim 13, characterised in that the detection device (30) is of the optical type and comprises at least one light source (228), each capable of emitting a light beam, and at least one photodetector (227), each capable of detecting the light emitted by a light source from said at least one light source, said indicator having a reflecting surface (RS1, RS2) which passes through the one or more light beams emitted by said at least one light source during passages of this indicator through said at least one reference time position, the detection device and the reflecting surface being configured such that this reflecting surface can reflect, upon a passage of said indicator through any reference time position from said at least one reference time position, the incident light, provided by a light source from said at least one light source, at least partially in the direction of a respective photodetector from said at least one photodetector.

15. Timepiece according to claim 14, characterised in that said reflecting surface is formed by a bottom surface of said indicator, said at least one light source and said at least one photodetector being supported by a dial (32) of the timepiece or housed at least partially in the dial, or situated beneath the dial which is thus arranged to allow the one or more light beams to pass therethrough.

16. Timepiece according to claim 14 or 15, characterised in that the light emitted by said at least one light source is not visible to the human eye.

17. Timepiece according to any of claims 1 to 12, characterised in that the detection device is arranged in the timepiece such that it can indirectly detect said passage of said indicator of the display through said at least one reference time position, the detection device being arranged such that it can detect at least one predetermined respective angular position of a wheel (264) integral with the indicator or a detection wheel (294), forming the drive mechanism or complementing same, which drives or which is driven by the wheel integral with the indicator; and in that the detection wheel (294), where appropriate, is selected or configured to have a rotational speed that is less than that of a rotating element (296) of said drive mechanism which is integral with said indicator and a gear ratio R with said rotating element that is equal to a positive integer or the inverse thereof depending on whether the detection wheel is respectively driving or driven.

18. Timepiece according to claim 17, wherein said indicator is a seconds indicator (262), characterised in that said wheel integral with the indicator is a seconds wheel (264), the detection device comprising a detection unit (274) associated with the seconds indicator and arranged such that it can detect a predetermined angular position of the seconds wheel.

19. Timepiece according to claim 17, wherein said indicator is a minutes indicator (34M), characterised in that said detection wheel is a minute wheel (294) which is driven in rotation by a cannon-pinion (296) forming the rotating element integral with the minutes indicator; and in that the detection device comprises at least one detection unit (302, 304) associated with the minutes indicator and arranged to be able to detect at least a first series of R given periodic angular positions of the minute wheel, two adjacent angular positions of this first series having a central angle equal to 360° / R therebetween.

20. Timepiece according to claim 19, characterised in that said detection unit (302, 304) is arranged such that it can further detect a second series of R given periodic angular positions of the minute wheel (294), which are different from the angular positions of the first series, two adjacent angular positions of the second series having a central angle equal to 360° / R therebetween; and in that the minute wheel is configured such that each angular position of the first series has the same first signature for the correction device (6; 132), such that the electronic correction circuit (40) can associate the same first reference time position with the minutes indicator upon the detection of any angular position of the first series, and such that each angular position of the second series has the same second signature, which is different from the first signature, for the correction device, such that this electronic correction circuit can associate the same second reference time position, which is different from the first reference time position, with the minutes indicator upon the detection of any angular position of the second series.

21. Timepiece according to claim 19 or 20, characterised in that the detection device comprises K detection units (302, 304; 302A, 304A), K being an integer greater than one, and the number of series of periodic angular positions of the minute wheel (294) is an integer S greater than zero, each series of periodic angular positions being associated with a respective plurality of R specific elements or specific recesses of the minute wheel, the K detection units being arranged such that they can each detect the S pluralities of R specific elements or specific recesses of the minute wheel; and in that any two of the K detection units are angularly offset by a separation angle, for which the remainder of the integer division by an angle equal to 360° / (R·S) is not zero, the number of reference time positions of the minutes indicator capable of being detected by the correction device being equal to S·K.

22. Timepiece according to claim 21, characterised in that S series of periodic angular positions are offset in pairs by an angle equal to 360° / (R·S) and said remainder of the integer division is substantially equal to 360° / (R·S·K).

23. Timepiece according to any of claims 19 to 22, characterised in that it comprises a plate (272) which supports, on the upper side, the minute wheel (294) and which bears the detection unit, which is arranged beneath the minute wheel.

24. Timepiece according to any of claims 18 to 23, characterised in that each detection unit is of the optical type and comprises a light source (302, 302A) and a photodetector (304, 304A) radially aligned with one another.

25. Timepiece according to any of the preceding claims, characterised in that the correction device (6; 132) is arranged such that it can be periodically activated, in an automatic manner, to carry out a correction cycle during which the detection device is activated for a said detection phase, so as to allow the electronic correction circuit (40) to determine a said overall time error, and the braking device is then activated to correct, during a said correction period, at least a large part of this overall time error.

26. Timepiece according to any of the preceding claims, characterised in that it further comprises a control member capable of being actuated by a user of the timepiece, this control member and the correction device being arranged to allow a user to activate the correction device so that this correction device carries out a correction cycle during which the detection device is activated for a said detection phase, so as to determine a said overall time error, and the braking device is activated to subsequently correct, during a said correction period, at least a large part of this overall time error.

27. Timepiece according to claim 26, characterised in that said control member is formed by a crown associated with a control stem which also act to manually set the display to the correct time.

28. Timepiece according to any of the preceding claims, characterised in that the correction device (6) further comprises a wireless communication unit (50), which is arranged such that it can communicate with an external system capable of providing the precise actual time, the correction device being arranged such that it can synchronise the reference actual time to a precise actual time, formed by current time units of the precise actual time corresponding to those of the reference actual time, during a synchronisation phase wherein the communication unit is activated so as to receive the precise actual time or said actual time from the external system.

29. Timepiece according to claim 28, characterised in that said communication unit (50) is periodically and automatically activated to synchronise the reference actual time to said precise actual time during a said synchronisation phase.

30. Timepiece according to claim 28 or 29, characterised in that it comprises a control member for synchronising the reference actual time to said precise actual time, this control member being capable of being actuated by a user of the timepiece, the control member for synchronising the reference actual time to said precise actual time and the correction device being arranged to allow a user to activate the correction device so that this correction device synchronises the reference actual time to said precise actual time during a said synchronisation phase.

31. Timepiece according to claim 30, characterised in that said member for synchronising the reference actual time to said precise actual time is formed by a crown associated with a control stem which also act to manually set the display to the correct time.

32. Timepiece according to any of the preceding claims, characterised in that it comprises a device (144; 192) for determining the passage of said oscillating mechanical resonator through at least one specific position, the device for determining this specific position of the mechanical resonator allowing said control unit to determine a specific moment at which the oscillating mechanical resonator is located in the specific position; and in that the control unit is arranged such that a first activation of the braking device occurring at the start of the correction period, to produce a first interaction between this braking device and the mechanical resonator, is initiated as a function of said specific moment.

33. Timepiece according to claim 32, wherein the horological movement comprises an escapement associated with the mechanical resonator, characterised in that the braking device comprises an actuator (174) provided with a stop member (184) for stopping the oscillating mechanical resonator, the stop member being capable of being actuated between a position of non-interaction with the mechanical resonator and a position of interaction wherein this stop member forms an abutment for a projecting part (190) of the oscillating mechanical resonator, the projecting part being arranged to abut against the stop member when the latter is in the position of interaction thereof, the stop member in the position of interaction thereof and the projecting part defining a stop position (θB) for the oscillating mechanical resonator which is different from the neutral position thereof, corresponding to the minimum potential energy state of the mechanical resonator, and less than a minimum amplitude of the oscillating mechanical resonator in the usable operating range thereof, said stop position further being provided such that the oscillating mechanical resonator is brought to a halt by the stop member outside a coupling zone (θZI) of the escapement with the oscillating mechanical resonator; and in that the circuit for determining said specific position of the oscillating mechanical resonator and said control unit are arranged such that they can activate the actuator, when said overall time error determined by the electronic correction circuit corresponds to a loss in the actual time displayed that is to be corrected, such that this actuator actuates the stop member thereof so that the projecting part (190) of the oscillating mechanical resonator comes to abut against this stop member (184) in a plurality of half-alternations of the oscillating mechanical resonator each of which follow the passage thereof through said neutral position, so as to prematurely end each of these half-alternations without blocking the mechanical resonator, the number of half-alternations of said plurality of half-alternations or a duration of the correction period during which the stop member is held in the position of interaction thereof being determined by said loss to be corrected.

34. Timepiece according to claim 33, characterised in that the device for determining at least one specific position of the oscillating mechanical resonator comprises a detector (192) for detecting the position and direction of motion of the mechanical resonator, this detector and the mechanical resonator being arranged to allow the passage of the oscillating mechanical resonator through said specific position ('0') in each period of the oscillation thereof to be detected and to allow the electronic correction circuit (196) to determine the direction of motion of the oscillating mechanical resonator in the alternation during which the passage of the oscillating mechanical resonator through the specific position is detected; and in that the electronic correction circuit is arranged such that it can at least partially correct said loss, such that it can control the actuator (174) so that this actuator actuates the stop member thereof from the position of non-interaction thereof into the position of interaction thereof when the oscillating mechanical resonator is situated on the neutral position side relative to said stop position, and so that the actuator subsequently holds the stop member in this position of interaction for a determined duration that is sufficient for the projecting part of the oscillating mechanical resonator to abut at least once against the stop member.

35. Timepiece according to claim 34, characterised in that said actuator (174) is of the bistable type and is arranged such that it can remain in the position of non-interaction and in the position of interaction without maintaining a power supply to this actuator; and in that the electronic correction circuit and the actuator are arranged such that, to at least partially correct said loss, the stop member (184) is maintained in the position of interaction thereof, after the stop member is actuated from the position of non-interaction thereof to the position of interaction thereof when the oscillating mechanical resonator is located on the neutral position side relative to said stop position, until the end of said correction period during which the projecting part (190) of the oscillating mechanical resonator periodically abuts several times against the stop member.

36. Timepiece according to claim 34 or 35, characterised in that said control unit comprises a measuring circuit which is associated with said detector for detecting the position and the direction of motion of the mechanical resonator, this measuring circuit comprising a clock circuit (42), providing a clock signal at a determined frequency (F0c / 2), and a comparator circuit (200) allowing a time drift of the oscillating mechanical resonator relative to the setpoint frequency thereof to be measured, the measuring circuit being arranged such that it can measure a time interval corresponding to a time drift of the mechanical resonator from the start of the correction period, the control unit being arranged to end the correction period as soon as said time interval is greater than or equal to said overall time error previously determined by the electronic correction circuit.

37. Timepiece according to any of claims 1 to 32, characterised in that the braking device is formed by an electromechanical actuator (22A; 22B), which is arranged such that it can apply braking pulses to the mechanical resonator, and the control unit comprises a device for generating at least one frequency (62) which is arranged such that it can generate a first periodic digital signal (SFS) at a frequency FSUP; in that the control unit (48A, 48B) is arranged to provide the braking device, when said overall time error previously determined by the electronic correction circuit corresponds to a displayed time loss that is to be corrected, with a first control signal (SC1, SAct (SFS)) derived from the first periodic digital signal, during a first correction period, to activate the braking device such that this braking device generates a first series of periodic braking pulses that are applied to the mechanical resonator at said frequency FSUP, the duration of the first correction period and thus the number of periodic braking pulses in said first series being determined by said loss to be corrected; and in that the frequency FSUP is provided and the braking device is arranged such that said first series of periodic braking pulses at the frequency FSUP can, during said first correction period, result in a first synchronous phase wherein the oscillation of the mechanical resonator (14) is synchronised with a correction frequency FSCor which is greater than a setpoint frequency F0c provided for the mechanical resonator.

38. Timepiece according to claim 37, characterised in that said device for generating at least one frequency is a frequency generator device (62, 142) which is arranged such that it can further generate a second periodic digital signal (SFI) at a frequency FINF; in that the control unit (48B) is arranged such that it can provide the braking device, when said overall time error previously determined by the electronic correction circuit corresponds to a displayed time gain that is to be corrected, with a second control signal (SAct (SFI)) derived from the second periodic digital signal, during a second correction period, to activate the braking device such that this braking device generates a second series of periodic braking pulses that are applied to the mechanical resonator at said frequency FINF, the duration of the second correction period and thus the number of periodic braking pulses in said second series being determined by said gain to be corrected; and in that the frequency FINF is provided and the braking device is arranged such that said second series of periodic braking pulses at the frequency FINF can, during said second correction period, result in a second synchronous phase wherein the oscillation of the mechanical resonator is synchronised to a correction frequency FICor which is less than the setpoint frequency F0c provided for the mechanical resonator.

39. Timepiece according to claim 37, wherein the horological movement comprises an escapement associated with the mechanical resonator, characterised in that said frequency FSUP and the duration of the braking pulses of the first series of periodic braking pulses are selected such that, during said first synchronous phase, each of the braking pulses of said first series occurs outside a coupling zone (θZI) of the oscillating mechanical resonator with the escapement.

40. Timepiece according to claim 38, wherein the horological movement comprises an escapement associated with the mechanical resonator, characterised in that said frequency FINF and the duration of the braking pulses of the second series of periodic braking pulses are selected such that, during said second synchronous phase, each of the braking pulses of said second series occurs outside a coupling zone (θZI) of the oscillating mechanical resonator with the escapement.

41. Timepiece according to any of claims 37 to 40, characterised in that the device for generating at least one frequency is a frequency generator device (62, 142, 144) which is arranged such that it can further generate a third periodic digital signal (SF0c) at the setpoint frequency F0c for the mechanical resonator; in that the control unit is arranged such that it can provide the braking device with a third control signal (SAct (SF0c)) derived from the third periodic digital signal, during a preliminary period preceding the correction period, to activate the braking device such that this braking device generates a preliminary series of periodic braking pulses which are applied to the mechanical resonator at the setpoint frequency F0c, the duration of these braking pulses and the braking force applied to the oscillating mechanical resonator during the preliminary series of periodic braking pulses being provided such that none of these braking pulses can bring the oscillating mechanical resonator to a halt inside a coupling zone (θZI) of the oscillating mechanical resonator with the escapement; the control unit being arranged such that the duration of the preliminary period and the braking force applied to the oscillating mechanical resonator during the preliminary series of periodic braking pulses allow, at least at the end of the preliminary period, a preliminary synchronous phase to be produced, wherein the oscillation of the mechanical resonator is synchronised to the setpoint frequency F0c; and in that the control unit is arranged such that the initiation of a first braking pulse of the first series of periodic braking pulses, during said correction period, occurs after a time interval determined relative to a moment at which the last braking pulse of the preliminary period was initiated, the moment at which said first braking pulse is initiated and the braking force applied to the oscillating mechanical resonator during said first series of periodic braking pulses being provided such that said first synchronous phase at said correction frequency FSCor starts instantly at said first braking pulse or a second braking pulse.

42. Timepiece according to any of the preceding claims, characterised in that it comprises a device (22; 106; 114; 174) for blocking the mechanical resonator; and in that the control unit is arranged such that it can provide the blocking device, when said overall time error previously determined by the electronic correction circuit corresponds to a displayed time gain that is to be corrected, with a fourth control signal which activates the blocking device such that this blocking device blocks said oscillation of the mechanical resonator during said correction period which is determined by said gain to be corrected, in order to stop the running of said drive mechanism during this correction period.

43. Timepiece according to claim 42, characterised in that said correction period has a duration that is substantially equal to said gain to be corrected.

44. Timepiece according to claim 42 or 43, characterised in that the blocking device is formed by a device (114) that is separate from said braking device and comprises a bistable lever (115), the first stable position of this bistable lever corresponding to a position of non-interaction with the mechanical resonator and the second stable position thereof corresponding to a position for halting and blocking the mechanical resonator.

45. Timepiece according to any of claims 42 to 44, characterised in that the blocking device (106) forms a lock for the mechanical resonator, a part (107) of this blocking device being inserted into a cavity (108), arranged in a circular element (100) of the balance forming the mechanical resonator, when the blocking device is activated to block this mechanical resonator during the period for correcting a given gain.

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