Patent Grant
11892807
This application claims priority to European Patent Application No. 19178785.2, filed on Jun. 6, 2019, the entire contents of which are incorporated herein by reference.
The invention relates to the field of the measurement of the precision of a timepiece comprising a continuous rotation electromechanical transducer, which is either arranged in the kinematic chain linking a power source to an analogue time display, or in kinematic linkage with such a kinematic chain. In particular, the invention relates to the measurement of the rate of such a horological movement, respectively of such a watch, and it also relates to the measurement of the precision of a quartz oscillator forming an internal electronic time base which is suitable for regulating the rotational speed of the electromechanical transducer.
The term rate denotes herein the daily time drift of the time displayed by the timepiece. The precision of the quartz oscillator may also be given in the form of a daily time drift. A daily time drift is measured relative to a very precise external time base which makes it possible to measure time intervals with a very high precision.
According to two main embodiments of the invention, the electromechanical transducer is formed respectively by a small generator linked with the kinematic chain linking a barrel, forming a source of mechanical energy, to an analogue time display and by a continuous rotation motor which is powered by a source of electrical energy and which drives, via a kinematic chain, an analogue time display.
The electromechanical transducers considered within the scope of the invention are generally reversible, such that they can either produce electrical energy from a source of mechanical energy while enabling regulation of the rotational speed of the rotor by braking this rotor in a controlled manner, or produce mechanical energy, more particularly a motor torque, from an electrical power supply. In the latter case, motor electrical impulses may be supplied to the stator so as to provide either a certain force couple, or a certain rotational speed, particularly a nominal rotational speed in a horological movement. Such transducers are also sometimes known as “electromagnetic transducers”, given that the rotor-stator coupling is of the electromagnetic type. Indeed, in motor mode, to switch from an electric current to a mechanical drive force of a time display mechanism, it is envisaged that such an electric current circulates in at least one coil so as to generate a magnetic field which is coupled with permanent magnets borne by the rotor. In generator mode, to switch from a mechanical drive force of the generator rotor to an electric current, which may power an electronic circuit for regulating the medium rotational speed of the rotor, a force couple rotates the rotor wherein the magnets then induce an electric current in the stator coil.
As regards horological generator designs and possible operations of such generators, reference may be made in particular to the documents EP 0679968, EP 0822470, EP 0935177, EP 1099990, and WO 00/63749. Regarding continuous rotation horological motor designs and possible operations of such continuous rotation motors, reference may be made in particular to the documents FR 2.076.493, CH 714041 and EP 0887913.
For conventional watches of the electromechanical type, i.e. watches comprising an electronic quartz movement associated with a stepping motor, it is known to be able to precisely measure the rate of such watches once they are cased up and ready for use, without having to open a back or a battery hatch. To do this, measurement apparatuses exist arranged to make precise time measurements between the steps of the motor, using a magnetic sensor capable of precisely detecting a certain time relative to each of the electrical impulses supplied to the stepping motors for the driving thereof. The electrical impulses induce magnetic impulses in the stator of the motor to rotate the rotor thereof which is equipped with at least one permanent magnet. The magnetic impulses are propagated partially outside the stator and they may be detected by a magnetic sensor outside the watch. Such measurement apparatuses can precisely determine the rate of the electromechanical watch given that the motor impulses are generated at regular time intervals, particularly each second, these time intervals being determined by the internal electronic time base, i.e. by the quartz oscillator which is inhibited in a manner known to adjust the medium frequency of this time base.
Unlike conventional electromechanical type watches which comprise a stepping motor, the timepieces comprising a continuous rotation electromechanical transducer in the movement thereof, as disclosed above, do not have a perfectly periodic event which is detectable from outside the timepiece by a measurement device of the type described above. Indeed, despite a regulation envisaged to servo-control the medium rotational speed of the continuous rotation electromechanical transducer such that the time displayed is on average correct and that there is no long-term time drift, the instantaneous rotational speed varying about the nominal rotation speed. Thus, in the particular case of a generator watch subject to a braking impulse in each alternation of the induced voltage signal generated in the coils of this generator, if the durations between these braking impulses are measured with suitable means and, as for the electromechanical watch with a stepping motor, a mean of these measurements is carried out to obtain a medium speed, a very long measurement period, for example one day, is then required to obtain the rate of the timepiece with a sufficient precision whereas for the electromechanical watch mentioned above, two minutes for example suffice to obtain the rate with a similar precision. The same problem arises in the particular case of a watch equipped with a continuous rotation motor which would receive a motor impulse at each period of the induced voltage signal mentioned above. Then, in the case where the braking impulses or the motor impulses are not envisaged regularly in each alternation or each period of the induced voltage signal, the measurement becomes even more problematic. It is therefore understood that there is a real need to find a method for measuring the rate of a completed watch wherein the time display mechanism is in kinematic linkage with a continuous rotation electromechanical transducer. ‘Completed watch’ denotes a watch wherein the watch case is closed with the movement mounted therein.
The aim of the present invention is to provide a method for measuring the rate of a timepiece wherein the time display mechanism comprises a kinematic chain between a motor device and the time display which incorporates a continuous rotation electromechanical transducer, accounting for the fact that the rotational speed of the rotor thereof is generally variable even if it is regulated to be on average equal to a nominal rotational speed.
To this end, the invention generally relates to a method for measuring the medium frequency of a digital signal which is derived from a reference periodic signal generated by an oscillator forming an electronic time base of a timepiece. The timepiece comprises a movement incorporating a mechanism formed by a kinematic chain which is arranged between a motor device of the movement and an analogue time display device, this kinematic chain comprising or being kinematically linked to a continuous rotation electromechanical transducer wherein the medium rotational speed is regulated by a regulation device, associated with the electronic time base, according to a nominal rotational speed. In the case of a continuous rotation motor, it is understood that it forms the abovementioned motor device. The regulation device is arranged to successively supply to the electromechanical transducer regulation impulses to regulate the medium rotational speed thereof, these regulation impulses defining respectively the same events which are synchronised on the rising edges or on the falling edges of said digital signal and which are detectable, by a measurement device without galvanic contact with the movement, at respective detection times having the same time phase-shift with said same events.
The measurement method comprises the following steps:
For a timepiece having a quartz oscillator forming the internal electronic time base thereof, it will be noted that this quartz oscillator is normally manufactured such that the inherent daily error thereof is positive, i.e. the natural frequency thereof is slightly greater than the theoretical frequency thereof, without however exceeding a maximum daily error, for example fifteen seconds per day.
According to a main embodiment of the measurement method, the digital signal is an inhibited digital signal which has periods of variable durations according to an inhibition of a certain number of periods of the reference periodic signal during successive inhibition cycles. Conventionally, the movement is arranged such that the medium frequency of the inhibited digital signal determines a gain of the indicator organs of the analogue time display device.
According to a preferred alternative embodiment of the main embodiment, the inhibition is performed according to a method which distributes the inhibition of the certain number of periods of the reference periodic signal during each inhibition cycle. Furthermore, the plurality of successive time intervals is envisaged such that the increase in the duration of any time interval among this plurality, resulting from the inhibition of one or more period(s) of the reference periodic signal during this time interval, is at most equal to half the theoretical medium period of the inhibited digital signal.
Then, the precision of the analogue time display device is determined by calculating a relative error given by the result of the division of the difference between the medium frequency of the inhibited digital signal, obtained in step E) mentioned above, and the theoretical medium frequency, for this inhibited digital signal, by this theoretical medium frequency.
Finally, the rate of the timepiece is obtained by multiplying the relative error mentioned above by the number of seconds in one day.
The measurement method according to the invention applies to a timepiece wherein the electromechanical generator is either a generator, or a continuous rotation motor.
The invention will be described hereinafter in a detailed manner with the aid of the appended drawings, given by way of non-limiting examples, wherein:
With the aid of the appended figures, an embodiment of the measurement method according to the invention will be described, applied to a timepiece 2 comprising in the movement 4 thereof a continuous rotation electromechanical generator 6 (hereinafter ‘the generator’), which has a kinematic linkage 9 with a kinematic chain 8 which is arranged between a barrel 10, defining a source of mechanical energy and forming a motor device, and a time display 12. The kinematic chain 8 comprises, in the alternative embodiment shown, a wheel assembly 8A and a geartrain 8B, represented schematically, engaged with the time display device 12 comprising the hands 14A, 14B, 14C.
As a general rule, the generator 6 is formed by a rotor equipped with permanent magnets and a stator comprising at least one coil through which a variable magnetic flux, which is generated by the magnets of the rotor when the latter is rotating, passes. In the alternative embodiment represented, the stator 16 comprises a support 20 bearing three coils 22A, 22B and 22C arranged regularly about the axis of rotation 19 of the rotor and connected to an electronic circuit 24. The rotor 18 comprises a central shaft 32 bearing two flanges 28A, 28B, preferably made of ferromagnetic material, on each whereof are arranged regularly, about the axis of rotation, six permanent magnets 30A and 30B having alternating polarities. In other words, two adjacent magnets 30A and 30B of the same flange has inverted polarities, whereas two magnets 30A or two magnets 30B, borne respectively by the two flanges and aligned along the direction of the axis of rotation 19, have the same polarity. The shaft 32 of the rotor bears a pinion 34 engaged with the wheel of the wheel assembly 8A. Thus, in the alternative embodiment represented, the kinematic linkage 9 is formed by the gearing of the pinion 34 with the wheel of the wheel assembly 8A.
The movement 4 further comprises a plate 36 and a bridge 38 wherein two bearing blocks 40A and 40B each equipped with a shock-resistant device and wherein the rotor 18 is pivoted are respectively arranged.
In
The regulation circuit 50 comprises a switch 52, formed by a transistor, which is controlled by a control unit 54. The switch 52 is arranged between the two terminals 44A and 44B of the stator 16, such that when this switch is closed, i.e. conducting, these two terminals are connected electrically and the voltage U1 is nil, the coils 22A-22C of the stator then being short-circuited. When the switch is open, i.e. non-conducting, the voltage U1 is proportional to the induced voltage in the three coils by the magnets of the rotating rotor. The medium rotational speed of the generator 6 is regulated, according to a nominal rotational speed, by a regulation device formed by the regulation circuit 50. The regulation circuit is associated with an electronic time base 25 which is formed by: —a quartz oscillator 26 which generate a reference periodic signal SPR, —a first frequency divider 60 which receives the reference periodic signal SPR and which supplies a periodic digital signal SDP the frequency FDP whereof is equal to the natural frequency FNR of the reference periodic signal SPR divided by a given whole number, for example two, and —second frequency divider 62 which receives the signal SDP and which supplies an inhibited digital signal SDI to a logic unit 64, which processes this inhibited digital signal to generate a clock signal SHo. The inhibited digital signal SDI is also supplied to the control unit 54. It will be noted that the first divider and the second divider generally form the first two stages of a division unit which also forms at least a first part of the logic unit 64.
In general, given that the manufacture of quartz oscillators does not enable the obtention of a very precise natural frequency, it is envisaged to produce quartz oscillators having a natural frequency greater than a theoretical reference frequency FRT, in a certain given frequency value range. In general, the theoretical reference frequency FRT is equal to 32,768 Hz. In the alternative embodiment described, the frequency divider 60 is a divider by two, such that the theoretical frequency FTDP of the digital signal SDP is equal to 16,384 Hz and the corresponding theoretical period PTDP equals 1/16,384 second. For example, the daily error of non-inhibited quartz oscillators is envisaged between one and twenty seconds.
The second frequency divider is associated with an inhibition unit 66 which, conventionally, inhibits a determined number of impulses in the digital signal SDP to correct a predetermined error of the quartz oscillator 26 resulting from manufacturing tolerances and due to the fact that, as previously stated, quartzes are produced so as to have an excessively high natural frequency in a certain range of frequencies above a theoretical reference frequency FRT. Then, for each quartz oscillator produced, the natural frequency FNR thereof is determined and a number of inhibitions per inhibition cycle is calculated, this number of inhibitions being introduced into the inhibition unit 66. In general, the inhibitions are distributed over each of the successive inhibition cycles. In a known alternative embodiment, an inhibition cycle lasts 64 seconds and the number of inhibitions determined is divided by this number of seconds to obtain a unitary inhibition number per second. The latter number is a real number. To each second during an inhibition cycle, the unitary inhibition number is added in a counter and the integer part of the result of the addition performed by this counter is inhibited, subsequently only retaining the remaining fractional part in the counter. Let us take two simple examples: a) the determined inhibition number is 32 and the unitary inhibition is therefore 0.5, such that the inhibition of a period of the periodic digital signal is envisaged every two seconds; b) the determined inhibition number is 96 and the unitary inhibition number is 1.5, such that one inhibition and two inhibitions are envisaged in alternation during the successive seconds of an inhibition cycle. It will be noted that, advantageously, when the unitary inhibition number is greater than one, inhibitions carried out during the same second are not accumulated in the same period of the inhibited digital signal, but are distant by a certain unitary time interval, for example of substantially 125 ms (⅛ second).
It will be noted that the inhibition of periods of the reference signal generated by the quartz, to adjust the precision of an electronic watch and thus reduce the rate thereof, is a technique well-known to those skilled in the art who know of various ways of implementing same. The present invention is therefore not limited to a single possible implementation, but to several known alternative embodiments insofar as certain conditions remain valid, as described hereinafter.
To regulate the speed of the generator, the clock signal SHo determines a set-point value for the frequency of the induced voltage in the coils, which corresponds to the frequency of the voltage signal U1. This set-point value is a function of the nominal rotational speed of the generator and it is determined by the time base 25, such that it is marred by an error corresponding to that of the time base. A voltage comparator 58, of which one input is connected to one of the terminals 44A, 44B and the other input to a reference voltage 59, generates a signal FUG which is supplied to a reversible counter 56 and to the control unit 54. More particularly, the signal FUG is a digital signal wherein the period corresponds to the electrical period of the generator, i.e. to the period of the induced voltage in the stator thereof and therefore of the voltage U1. This signal FUG decrements the reversible counter 56 at each electrical period detected while the logic unit 64 increments this reversible counter at each period of the clock signal SHo. Thus, the reversible counter integrates, from a start time, a time drift of the generator and therefore of the analogue time display relative to a set-point gain determined by the set-point value which is derived from the inhibited digital signal supplied by the internal time base 25. The state of the reversible counter is supplied to the control unit 54 which manages the medium rotational speed of the generator according to a given method.
The regulation circuit 50 is arranged to successively supply regulation impulses to the generator to regulate the medium rotational speed thereof such that it is as close as possible to a nominal rotational speed envisaged for the generator rotor. The regulation impulses are formed herein by braking impulses of the generator rotor which are each generated by a momentary short-circuit of the coil(s) forming the stator of this generator. The nominal rotational speed is determined by the design of the movement 4, in particular by the kinematic chain 8 and the kinematic linkage 9. In the alternative embodiment described herein, the nominal rotational speed is equal to 64/9=7.1111 revolutions per second. For the generator described above, the nominal electrical frequency of the alternating voltage signal U1 is that of the induced voltage in the three coils thereof. It equals triple the nominal rotational speed, i.e. 64/3=21.3333 Hz. Thus, the nominal electrical period equals 46.875 ms and the nominal duration of an alternation of the signal U1 is equal exactly to 23.4375 ms.
In
As a general rule, the measurement method according to the invention envisages measuring, in particular for a timepiece 2 such as a wristwatch or for a movement 4 ready to be cased up, the medium frequency of an internal digital signal of the electronic circuit of the movement 4, this digital signal being derived from the reference periodic signal SPR generated by the quartz oscillator 26 forming the electronic time base 25 of this movement 4. It is envisaged that the medium rotational speed of the generator 6 is regulated by a regulation circuit, associated with the electronic time base, according to a nominal rotational speed. The regulation device is arranged to be able to successively supply braking impulses to the generator by short-circuiting the terminals 44A and 44B of the coils of the stator 16 of the generator in order to regulate the medium rotational speed thereof. The control unit 54 of the regulation device generates each of the braking impulses as follows: When it is envisaged to generate a braking pulse with a view to regulating the rotational speed of the generator, particularly according to the state of the reversible counter 56 or optionally also further detected events, the control unit waits to detect in the digital signal FUG from the comparator 58, according to the alternative embodiment, either a next rising edge, or a following edge among the rising and falling edges; then it triggers directly or after a given delay the braking pulse, via the control signal SCom that it supplies to the switch 52, by closing this switch at a time tdn, n=1, 2, 3, . . . . In a specific alternative embodiment, as shown in
Within the scope of the invention, the regulation impulses respectively define the same events which are synchronised on the rising edges or on the falling edges of the inhibited digital signal SDI and which are detectable, by a measurement device without galvanic contact with the movement and preferably by a magnetic field sensor 72, at corresponding detection times. In a main embodiment of the measurement method according to the invention described with the aid of the figures, this event is the end of each braking impulse. As shown in
In the alternative embodiment represented, the signal SDI has a medium frequency FMDI which is, over an inhibition cycle, slightly less than a quarter of the medium frequency FMDP of the periodic digital signal SDP. The inhibited digital signal SDI is derived from the signal SDP with the application of the inhibition envisaged to correct the relative error of the quartz oscillator. To generate the inhibited digital signal SDI, the periodic digital signal SDP is divided twice by two in the divider 62 by applying the inhibition during the first of these successive two divisions by two. To explain how the inhibition occurs, in
In the alternative embodiment described in the figures, the theoretical frequency FTDP=16,384 Hz and the theoretical period PTDP=1/16,384 second. Then, the theoretical medium frequency FMTDI equals FTDP/4, i.e. FMTDI=4,096 Hz, and the theoretical medium period PMTDI=1/4,096 second. Finally, it will be noted that the natural frequency FNR of the reference periodic signal SPR also has, over an inhibition cycle or a total measurement duration, a medium natural frequency FMNR which equals double the medium frequency FMDP of the signal SDP. To these frequencies FNR and FMNR corresponds the theoretical reference frequency FRT=32,768 Hz, which is, by design of the oscillator, less than the natural frequency FNR.
With the aid of
In step A), the end times are detected herein by a magnetic sensor 72 of the measurement device which is arranged to be able to detect short induced voltage impulses DEn, n=1, 2, 3, . . . , occurring at the end of the braking impulses BPn given the sudden drop in the induced current in the generator stator coils when the switch 52 is opened (rendered non-conducting) at the end of each braking impulse. To detect specifically the same specific time of the induced voltage impulses DEn, two comparators in parallel are envisaged which detect, on the rising edge of these impulses, the time when the induced voltage reaches a threshold voltage Us or −US respectively for positive and negative impulses succeeding each other in alternation, given that the braking impulses are carried out at each alternation of the voltage U1 at the terminals of the stator 16 of the generator 6. It will be noted that the detection times have the same small time phase-shift with the respective ends of the corresponding braking impulses.
As stated above, within the scope of the invention, it is envisaged to measure either the medium frequency FMDI of the inhibited digital signal SDI, so as to be able to finally determine the rate of the timepiece, or the medium frequency FMDP of the periodic digital signal SDP so as to be able to determine the precision of the oscillator 26 (generally a quartz oscillator) supplying the reference periodic signal SPR. Thus, in a first alternative embodiment, the digital signal is the periodic digital signal SDP wherein the medium frequency FMDP is equal to the medium natural frequency FMNR, over the total measurement duration TMes, of the reference periodic signal SPR divided by a given whole number, for example by two. The precision of the oscillator is determined by calculating a relative error ER(SDP) given by the result of the division of the difference between the medium frequency FMDP of the signal SDP, obtained in step E), and the theoretical frequency FTDP of this signal SDP by this theoretical frequency, i.e. ER(SDP)=(FMDP−FTDP)/FTDP. It will be noted that the relative error of the reference periodic signal SPR generated by the oscillator 26 is identical, i.e. ER(SPR)=ER(SDP). In a second alternative embodiment, the digital signal is therefore the inhibited digital signal SDI which has periods PDI and PDI* of variable durations according to an inhibition of a certain number of periods of the reference periodic signal during successive inhibition cycles. The medium frequency FMDI of the inhibited digital signal determining a gain of the indicator organs 14A to 14C of the analogue time display device 12, the precision of the analogue time display device is determined by calculating a relative error ER(SDI) given by the result of the division of the difference between the medium frequency FMDI of the inhibited digital signal SDI, obtained in step E), and the theoretical medium frequency FMTDI of this signal SDI by this theoretical medium frequency, i.e. ER(SDI)=(FMDI−FMTDI)/FMTDI. The rate of the timepiece is obtained by multiplying the relative error ER(SDI) by the number of seconds in one day, i.e. Rate=ER(SDI)·86,400[s/day].
By way of example, taking the measurement results given in the table in
It will be noted that the time intervals TIn follow one another without interruption. Thus, the total measurement duration TMes consists of a plurality of time intervals TIn, n=1, 2, 3, . . . , N, which are contiguous, these time intervals being measured by measurement device very precisely. The total measurement duration TMes therefore corresponds to an uninterrupted period of time between a start time tf0 and an end time tfN. This advantageous alternative embodiment is optional for the measurement of the medium frequency of the periodic digital signal SDP, but it is preferable for the inhibited digital signal SDI as the inhibitions do not generally occur at each time interval TIn and these inhibitions are not necessarily distributed perfectly homogeneously over time.
It will be noted that the total measurement duration TMes is envisaged very slightly greater than the duration of an inhibition cycle CInh which equals herein theoretically 64 seconds. In fact, the last time interval TIn corresponds to the time interval, between two ends tfN-1 and tfN of braking impulses, during which the end of a time measurement of an inhibition cycle CInh from the end time tf0 of an initial braking impulse BP0 occurs, this time tf0 being selected as the start of the measurement. The time measurement of an inhibition cycle is also performed by the measurement device which comprises or is associated with a very precise external time base, for example an atomic time base. In the alternative embodiment represented, the total number N of contiguous time intervals is equal to 2731, i.e. N=2731. The nominal electrical frequency of the voltage signal U1 is equal to 64/3 Hz. The nominal electrical period therefore equals 46.8750 milliseconds. Thus, the nominal duration of an alternation of the voltage signal U1 equals 23.4375 ms. 2731 alternations at this nominal duration gives a total duration slightly greater than 64 s, i.e. 64.0078125 s. It will be noted that the nominal duration of an alternation corresponds exactly to 96 theoretical medium periods PMTDI=1/4,096 s of the signal SDI and to 384 theoretical periods PTDP=1/16,384 s of the signal SDP.
The table in
The total number of inhibitions in the alternative embodiment described is equal to 110. This number is equal to the difference between the total number of periods TNP (SDP)=1,048,810 and the total of periods TNP (SDI)=262,175 multiplied by the factor ‘4’ mentioned above. By means of the rounding performed in the measurement method according to the invention, it is possible to determine both the effective number of periods of the periodic digital signal SDP, which is not inhibited, and the effective number of periods of the inhibited digital signal SDI, which is derived from the signal SDP with the application of the inhibition process to correct the error of this signal SDP. The consequence of the rounding performed on the real numbers NRn(SDI) to obtain the whole numbers Mn(SDi) is that these whole numbers Mn(SDi) are independent due to an inhibition having taken place or not during the corresponding time interval TIn. Thus, by means of the measurement method according to the invention, despite the fact that the electromechanical transducer has a variable rotational speed, the effective numbers of periods of the inhibited digital signal SDI during the time intervals TIn, which are dependent on the regulation impulses applied to the electromechanical transducer, are determined, these regulation impulses optionally occurring during each of these time intervals. Furthermore, within the scope of the measurement method according to the invention, it is possible to determine the effective numbers of periods of the periodic digital signal SDP, which is not inhibited, during the time intervals TIn and thus determine, besides the precision of the internal oscillator, the number of inhibitions per inhibition cycle envisaged for the timepiece in question and which is stored, at the time of the measurement, in a memory of the inhibition unit 66 or an internal memory accessible to this inhibition unit. It will be noted that this number of inhibitions may generally be replaced or corrected, particularly following an observation that the rate of the timepiece is not optimal or outside a specific range envisaged for the timepiece in question. The theoretical real number NTIC of inhibitions per inhibition cycle to be envisaged is calculated readily by multiplying the duration of an inhibition cycle CInh by the relative error ER(SPR) of the reference frequency and by dividing the result by the medium period PMDP of the periodic digital signal SDP whereon the inhibitions are performed, i.e. NTIC=CInh·ER(SDP)/PMDP as ER(SPR)=ER(SDP). For the alternative embodiment described, this gives NTIC=110.112.
In a further alternative embodiment, a braking impulse is envisaged at each period of the voltage U1, such that only the positive induced voltage impulses DE2n−1 or only the negative induced voltage impulses DE2n appear (see
To ensure a high precision of the measurement method according to the invention, three conditions described hereinafter are advantageously to be fulfilled.
The first condition sets a maximum duration for the measured time intervals TIn. The measurement of the plurality of successive time intervals TIn in step A) is performed such that each is less than a maximum duration TIMax which is equal to the theoretical medium period for the digital signal in question divided by double the maximum relative error ERMax for the natural frequency FNR of the reference periodic signal SPR relative to a theoretical reference frequency FRT, i.e. TIMax(SDP)=PTDP/2·ERMax(FNR) for the measurement of the medium frequency FMDP of the periodic digital signal SDP, i.e. TIMax(SDI)=PMTDI/2·ERMax(FNR) for the measurement of the medium frequency FMDI of the inhibited digital signal SDI. As the measurement method is based on a rounding to the nearest integer value, to obtain a whole number of periods Mn(SDP), respectively Mn(SDI) of the digital signal in question which corresponds for each time interval TIn to the effective whole number of periods of the digital signal in question, each real number obtained NRn(SDP), respectively NRn(SDI) must deviate from the maximum by a half-period of the digital signal in question relative to the whole number Mn(SDP), respectively Mn(SDi). As PMTDI=4·PTDP, it is understood that the strictest condition for the measurement of the medium frequency FMDP of the signal SDP and therefore of the precision of the oscillator of the internal time base. Furthermore, for the signal SDI, as inhibitions are envisaged to correct the error of the oscillator and these inhibitions are generally distributed during the inhibition cycles, the first condition discussed herein is not necessary to ensure a high measurement precision but it makes it possible to provide a high precision in all cases. By way of numerical example, if a maximum oscillator of twenty seconds/day is chosen, ERMax(FNR) equals approximately 230 ppm (0.00023), TIMax(SDP)=132.7 ms and TIMax(SDI)=530.8 ms. In the alternative embodiment in question, the theoretical duration of an alternation of the signal U1 is equal to 23.4375 ms, such that at least one braking impulse every five alternations is needed to measure the medium frequency of the oscillator precisely, respectively at least one braking impulse every twenty-two alternations to measure precisely, in the absence of inhibition during at least one of the time intervals TIn, the medium frequency of the inhibited digital signal and therefore the rate of the timepiece.
The second condition relates to the maximum number of inhibitions that may occur during each time interval TIn. With the aim of obtaining a whole number of periods Mn(SDI) of the inhibited digital signal SDI that corresponds, for each of the time intervals TIn, to the effective whole number of periods of this inhibited digital signal, the plurality of successive time intervals is envisaged such that the increase of the duration of any time interval among this plurality, resulting from the inhibition of one or more period(s) of the reference periodic signal during this time interval, is at most equal to half the theoretical medium period PMTDI of the inhibited digital signal (it being understood that a number equaling an integer and a half is rounded to this integer). In the alternative embodiment described, periods of the periodic digital signal SDP are inhibited. As the ratio between the theoretical medium period PMTDI of the inhibited digital signal and the theoretical period PTDP of the signal SDP equals four, i.e. PMTDI=PTDP/4, this second condition implies for this alternative embodiment that there are at most two inhibitions per time interval TIn. As the period PDP of the signal SDP is practically less than the theoretical period PTDP, there is a certain margin by limiting the inhibitions per measured time interval to two inhibitions.
It will be noted that the second condition is advantageous to provide a high measurement precision in all cases, but it is not necessary in all cases. Indeed, in an embodiment of the inhibition process which distributes the inhibitions during an inhibition cycle according to a substantially uniform schedule, for example by distributing at best the number of inhibitions in subperiods of the inhibition cycles and avoiding carrying out in these subperiods more than two impulses in a short time interval, there could be more than two inhibitions per time interval if the time intervals TIn are, in an alternative embodiment, relatively long. With a braking impulse for every alternation, as in the alternative embodiment described above, it is observed that the maximum number of inhibitions during each alternation is indeed equal to two. In the table in
The third condition to ensure a high measurement precision relates to the total measurement duration TMes for measuring the medium frequency of the inhibited digital signal and the rate of the timepiece. As stated, conventional inhibition processes envisage distributing the inhibitions during each inhibition cycle. In a particular embodiment, the inhibitions, of which the maximum whole number per inhibition cycle is 255 or 511, are distributed per second. An inhibition cycle lasts theoretically 64 [s]. As already described above, in each subperiod of a second, a whole number of inhibitions, corresponding to the integer value of the total number of inhibitions envisaged divided by 64, is performed, and an additional inhibition corresponding to the summation of the fractional parts during the seconds is periodically added, whenever this summation exceeds the unit. In each subperiod of one second, it is envisaged to perform the inhibitions every TU=125 ms, commencing at the start of the subperiod. Thus, if these impulses are envisaged in a given subperiod, the first occurs at the zero time of this subperiod, the second after 125 ms and the third after 250 ms (=2·TU). Then, there is no more inhibition in this subperiod, namely for slightly less than 750 ms.
As it is not known at which time in an inhibition cycle that the first time interval TI1 of the measurement method is started, it is advantageously envisaged that the total measurement duration TMes encompasses as close to entirely as possible an inhibition cycle to be sure that all the inhibitions envisaged for an inhibition cycle have occurred during the plurality of measured time intervals TIn. However, as the time intervals are determined by the braking impulses which are particularly dependent on the variable rotational speed of the generator, it is practically not possible to obtain a total measurement duration TMes exactly equal to an inhibition cycle. Consequently, in a preferred alternative embodiment, it is envisaged to end the measurements of the time intervals at the first braking impulse according to a time period corresponding to an inhibition cycle. Thus, TMes=CInh+Tadd. It will be noted that the probability of an inhibition impulse being counted in excess is high, or even more than one inhibition if the additional duration Tadd were to exceed TU=125 ms. To prevent this, in a preferred alternative embodiment, it is envisaged that the time intervals TIn are less than TU/2. In the alternative embodiment in question, this means that at least one braking impulse is needed for each electrical period of the voltage signal U1. Furthermore, it is envisaged to start the first time interval TI1 at the end of the braking impulse directly following the detection of an inhibition. Thus, it is ensured that an inhibition is not counted in excess relative to the total number of inhibitions envisaged in an inhibition cycle. In the preferred alternative embodiment disclosed herein, it is therefore envisaged to perform time interval measurements between braking impulses and make the calculations described in relation to the table in
In
Finally, any teaching provided in the present description of the invention in relation to a timepiece equipped with a generator also applies, by analogy, to a timepiece equipped with a continuous rotation motor and an electrical power supply to power this motor with motor electrical impulses. In such an embodiment, the electromechanical transducer is thus a continuous rotation motor forming the motor device of the horological movement. This motor is formed by a rotor equipped with permanent magnets and a stator comprising at least one coil through which a variable magnetic flux, which is generated by the magnets of the rotor when the latter is rotating, passes. In this case, the regulation impulses are motor impulses which are each generated by a momentary electrical power supply of said at least one stator coil. To do this, the switch 52 of the regulation circuit is then arranged between an electrical terminal of the stator and a terminal of the electrical power supply suitable for delivering a certain power supply current to the coil.
| Number | Date | Country | Kind |
|---|---|---|---|
| 19178785 | Jun 2019 | EP | regional |
| Number | Name | Date | Kind |
|---|---|---|---|
| 3696258 | Anderson | Oct 1972 | A |
| 20050036405 | Born | Feb 2005 | A1 |
| 20050073913 | Born | Apr 2005 | A1 |
| 20190187624 | Tombez | Jun 2019 | A1 |
| 20200387114 | Born | Dec 2020 | A1 |
| Number | Date | Country |
|---|---|---|
| 713306 | Jun 2018 | CH |
| 714041 | Feb 2019 | CH |
| 1176415 | Mar 1998 | CN |
| 1187643 | Jul 1998 | CN |
| 1204885 | Jan 1999 | CN |
| 0 679 968 | Nov 1995 | EP |
| 0 806 710 | Nov 1997 | EP |
| 0 822 470 | Feb 1998 | EP |
| Entry |
|---|
| “Analyzer Twin”, Witschi Electronic Ltd, URL: https://www.witschi.com/assets/files/sheets/leaflet_analyzer-Twin.pdf, May 31, 2011, XP055636846. |
| European Search Report for EP 19 17 8785 dated Oct. 29, 2019. |
| Office Action dated Jun. 15, 2021 from the China National Intellectual Property Administration in CN Application No. 202010505160.7. |
| Number | Date | Country | |
|---|---|---|---|
| 20200387114 A1 | Dec 2020 | US |
