Method for the chronometric testing of a timepiece movement

Abstract

Method for the chronometric testing or chronometric certification of a timepiece movement (100) or of a timepiece (200), in particular a method for calculating a chronometric state, comprising: - a step of acquiring data relating to the operation of the timepiece movement (100) or of the timepiece (200), - a step of processing the data so as to determine a jump time of a time display member (1), in particular of a seconds hand (1), of the timepiece movement (100) or of the timepiece (200).

Description

[0001] Process for chronometric control of a watch movement.

[0002] The invention relates to a method for chronometric testing or chronometric certification of a watch movement or a timepiece. The invention also relates to a device for chronometric testing or chronometric certification of a watch movement or a timepiece. The invention also relates to a method for producing or adjusting a timepiece or a watch movement. The invention further relates to a watch movement obtained by implementing such a production or adjustment method. The invention finally relates to a timepiece obtained by implementing such a production or adjustment method.

[0003] Measuring the rate of a wristwatch while wearing it is difficult to achieve with good precision. It is known to use a standard chronometric measuring device to obtain an instantaneous value of the rate. To do this, the watch is placed on the measuring device in well-defined positions, and the noises of the movement, and more specifically of the escapement, are captured. Although relatively accurate, this measurement provides absolutely no information on the behavior of the watch on the wearer's arm. However, the most important quantity to determine is the rate of the watch while wearing it, because the stresses of the watch on the wrist can significantly influence the rate of the watch, and each wearer will stress their watch in a very individual way.

[0004] To determine the rate of wear, a procedure is generally implemented based on at least two measurements, by evaluating the time displayed by the watch at two different times and comparing the elapsed time as displayed by the watch (and therefore representative of the average rate over the period separating the two measurement times) and the actual elapsed time given by a reference clock. This technique is commonly used by certification bodies, such as the Swiss Official Chronometer Testing Institute (COSC, which carries out certifications according to the ISO 3159 standard), with a duration of typically 24 hours between two measurements.

[0005] There is, however, a need to increase the accuracy of the measurement, as the level of precision required for a wristwatch tends to increase, resulting in a reduction in the tolerance intervals. In addition, it is desirable to reduce the time interval between two measurements to the strict minimum, so as to reduce the downtime of the watch and / or to allow more frequent measurements.

[0006] The state is defined as the difference between the time displayed by the watch and the "true" time, approximated by a "reference time" given by a reference clock. The displayed time varies approximately as time (slope of about 86400 s / d) while the state remains approximately constant as a function of time. The derivative of the state with respect to time is commonly called "the rate".

[0007] A state measurement is a determination of the displayed time associated with a reference time, and may in particular include an image measurement with a determination of the position of the hands (manual or automatic). To calculate a rate from images of the dial, two state measurements are required, spaced a certain time apart, and the difference between them is calculated. The associated quantity being the rate, and more precisely the average rate between the two state measurements, it is the difference in state between two state measurements that must be determined.

[0008] The so-called "diurnal" rate (as opposed to "instantaneous" rate) is defined by the ratio between the difference in state, generally in [s], and the elapsed (true) time, generally in [d], between the two state readings. Strictly speaking, the diurnal rate is the difference between two states separated by a time interval of 24 hours (definition from the Berner dictionary) but this definition is generalized for a "long" time interval, of a few hours or more. The instantaneous rate is determined by measuring the oscillation frequency of the balance-spring oscillator during a very short time interval, of the order of a few seconds or a few minutes, with a measurement which is carried out by an acoustic or optical chronocomparator. The diurnal rate corresponds as a first approximation to the instantaneous rate averaged over a certain duration.

[0009] To summarize, from a definitional point of view, we note:

[0010] - tdis: the time displayed by the watch;

[0011] - tREF: the time given by the reference clock;

[0012] - state = tdis - tREF: the difference between the displayed time and the reference time;

[0013] - march = (state[t2]-state[t1]) / (tREF[t2]-tREF[t1]), which means that:

[0014] - walk = ((tdis[t2]-tdis[t1 ]) / (tREF [t2]-tREF [t1 ]))-1 , as determined with two state captures spaced by a time corresponding to t2-t1 . The walk is a relative ratio between two durations, and is therefore dimensionless. To facilitate understanding, we generally multiply the walk by 86400 to express it in [s / d].

[0015] Usually, the determination of the rate of a watch by taking state measurements is carried out by the following steps:

[0016] - An image of the watch face and hands is acquired at a given time and the time the image was taken is recorded based on a reference clock (tREF), for example the time tREF given by the reference clock at the time the image was acquired;

[0017] - The position of the hands is determined on the image in relation to at least one reference representative of the orientation of the dial, for example the center and "noon", and the displayed time (tdis) is calculated on this basis;

[0018] - The state is calculated by the difference between the displayed time and the reference time: state = tdis-tREF;

[0019] - With two status measurements spaced a certain time apart (for example, 24 hours), the rate is calculated using the formula above. By following this approach, the owner identified various problems:

[0020] - Detection errors, needle overlap, distortion (e.g. when passing the needles under a magnifying glass or cyclops), etc. give rise to aberrant values, and require manual correction or repetition of the measurement;

[0021] - The time cannot always be determined completely or unequivocally, for example if not all the hands are available, as is the case when measuring with only the second hand, or if the watch is not set to the time and is in some other state, leading, for example, to possible confusion between morning and afternoon;

[0022] - Any phase shift between the second and minute hands can cause errors of one minute on the status.

[0023] Document EP2458458 describes the principle of a measurement by state captures, with two images taken at two different, clearly identified times. The position of the hands is identified by superimposing images. The document also mentions the possibility of carrying out measurements of state differences over short periods, of the order of a minute or an hour, as well as the possibility of carrying out successive measurements to calculate an average precision by averaging the values.

[0024] Document EP3719589 describes a device for winding and resetting a watch, including state correction means, and mentions state measurement means comprising a vision system, without any details on the arrangement of the means and on the measurement procedures.

[0025] The aim of the invention is to provide a chronometric control method whose efficiency is optimized and to improve the chronometric control methods known from the prior art. In particular, the invention proposes a chronometric control method whose precision is improved and / or whose implementation time is reduced.

[0026] According to a first aspect, the invention is defined by the following propositions.

[0027] 1. Method for chronometric control or chronometric certification of a watch movement (100) or a timepiece (200), in particular a method for calculating a chronometric state, comprising:

[0028] - a step of acquiring data relating to the operation of the watch movement (100) or the timepiece (200),

[0029] - a step of processing the data so as to determine a jump instant of a time display member (1), in particular a second hand (1), of the watch movement (100) or of the timepiece (200).

[0030] For example, the jump of a time display organ (1) is an unstable transient phase between two successive stable positions of the time display organ.

[0031] 2. Method according to proposition 1, characterized in that the data acquisition step comprises the acquisition of acoustic and / or magnetic and / or optical data, and in that the data processing step comprises the determination of a first date (Ttic) associated with the jump instant of the time display member.

[0032] 3. Method according to proposition 1 or 2, characterized in that the data acquisition step comprises the acquisition of a first series of images of the time display member, this acquisition being in particular:

[0033] - carried out at a frequency (f1) at least 10 times higher or at least 20 times higher than the jumping frequency (fs) of the time display organ, and / or

[0034] - carried out for a duration such that the time display member is in several successive stable positions, in particular in two successive stable positions. Method according to the preceding proposal, characterized in that the data processing step comprises:

[0035] - the determination and selection of at least one image from the first series of images taken at the time of a jump or temporally as close as possible to a jump of the time display organ, and

[0036] - the determination of a first date (Ttic) associated with the time display member's jump time as being the date of taking at least one image of the first series of images taken at the time of a jump or temporally as close as possible to a jump of the time display member and,

[0037] - optionally, determining a position of the time display member associated with this first date. Method according to proposition 3, characterized in that the data processing step comprises:

[0038] - the determination and selection of at least two images from the first series of images taken at the time of a jump or temporally as close as possible to a jump of the time display organ, and

[0039] - determining a first date (Ttic) associated with the jump time of the time display member by calculation using the dates of the taking of the at least two images, in particular by determining the time of starting the movement of the time display member or the time of stopping the movement of the time display member or the time at which the speed of the display member is maximum, and,

[0040] - optionally, determining a position of the time display member associated with this first date. Method according to proposition 3, characterized in that the data acquisition step comprises acquiring an image of the time display member for a period during which it occupies two successive stable positions and in that the data processing step comprises:

[0041] - the determination of a first date (Ttic) associated with the instant of jump of the time display member, between the two successive stable positions, by calculation by analyzing the apparent intensities of the display member on the image in the two successive stable positions, and,

[0042] - optionally, determining a position of the time display member associated with this first date. Method according to one of the preceding proposals, characterized in that the data acquisition step comprises the acquisition of a second series of images of the time display member, in particular distinct from the first series of images. Method according to the preceding proposal, characterized in that the acquisition of the second series of images of the time display member comprises at least one image capture separated from the jump time of the time display member (1) by a time:

[0043] - greater than n periods of movement of the time display organ increased by a jump time of the time display organ, and

[0044] - less than n+1 periods of movement of the time display member reduced by a jump time of the time display member, for example a time of n+0.5 periods of movement of the time display member, with n an integer. Method according to proposition 7, characterized in that the acquisition of the second series of images of the time display member comprises at least two image captures separated by a time:

[0045] - greater than n periods of movement of the time display organ increased by a jump time of the time display organ, and

[0046] - less than n+1 periods of movement of the time display member reduced by a jump time of the time display member, for example a time of n+0.5 periods of movement of the time display member, with n an integer.

[0047] 10. Method according to proposition 7 or 9, characterized in that the acquisition of the second series of images of the time display member is carried out over a period during which the time display member is in several successive stable positions.

[0048] 11. Method according to the preceding proposal, characterized in that the data processing step comprises the identification of images from the second series of images taken while the time display member is in motion and / or on which the position of the time display member cannot be correctly identified, and the exclusion of these images from the second series of images.

[0049] 12. Method according to one of proposals 7 to 11, characterized in that the data processing step comprises the determination of a second or second positions of the time display member associated with the images of the second series of images.

[0050] 13. Method according to one of propositions 7 to 12, characterized in that the data processing step comprises the use of a second date or dates (Ts) associated with the taking of the images of the second series of images. Method according to proposition 13, characterized in that the data processing step comprises the calculation of a third date or dates (Tref) associated with a jump of the display member preceding or following the second date or dates (Ts). Method according to the preceding proposition, characterized in that the data processing step comprises a running calculation and / or a state calculation using the third jump date(s) (Tref) or at least one jump instant deduced from the third date(s) (Tref).Device (10) for chronometric control or chronometric certification of a timepiece (200) or a watch movement (100), comprising hardware elements (11, 12, 13, 14, 15) and / or software implementing the method according to one of the preceding proposals. Method for producing or adjusting a timepiece (200) or a watch movement (100), the method comprising a step of implementing the chronometric control method according to one of proposals 1 to 15. Method for producing or adjusting according to the preceding proposal, the method comprising at least one adjustment step, in particular an adjustment step dependent on a rate deviation between a target value and a measured value. Timepiece (200), in particular a wristwatch, or watch movement (100) obtained by implementing the method according to one of proposals 17 and 18.Computer program product downloadable from a communications network and / or recorded on a data medium readable by a computer and / or executable by a computer, characterized in that it comprises instructions which, when the program is executed by the computer, lead the latter to implement the method according to any one of propositions 1 to 15.

[0051] 21. A computer-readable recording medium (15) comprising instructions which, when executed by a computer, cause the computer to implement the method according to any one of propositions 1 to 15.

[0052] 22. Signal of a data carrier, carrying the computer program product according to proposition 20.

[0053] According to a second aspect, the invention is defined by the following propositions.

[0054] 23. Method for chronometric control or chronometric certification of a watch movement (100) or a timepiece (200), in particular a method for calculating a chronometric state, comprising a step of acquiring data relating to the operation of the watch movement (100) or the timepiece (200), this step comprising two image captures separated by a time:

[0055] - greater than n periods of movement of the time display organ increased by a jump time of the time display organ, and

[0056] - less than n+1 periods of movement of the time display organ reduced by a jump time of the time display organ,

[0057] - for example a time of n+0.5 periods of movement of the time display organ, with n an integer.

[0058] 24. Method according to proposition 23, characterized in that:

[0059] - the method comprises a step of processing the data so as to determine a jump instant of a time display member (1), in particular of a second hand (1), of the watch movement (100) or of the timepiece (200), and / or

[0060] - the data acquisition step comprises the acquisition of acoustic and / or magnetic and / or optical data, and the data processing step comprises the determination of a first date (Ttic) associated with the jump instant of the time display member. Method according to proposition 23 or 24, characterized in that the data acquisition step comprises the acquisition of a first series of images of the time display member, this acquisition being in particular:

[0061] - carried out at a frequency (f1) at least 10 times higher or at least 20 times higher than the jumping frequency (fs) of the time display organ, and / or

[0062] - carried out for a duration such that the time display member is in several successive stable positions, in particular in two successive stable positions. Method according to proposition 25, characterized in that the data processing step comprises:

[0063] - the determination and selection of at least one image from the first series of images taken at the time of a jump or temporally as close as possible to a jump of the time display organ, and

[0064] - the determination of a first date (Ttic) associated with the time display member's jump time as being the date of taking at least one image of the first series of images taken at the time of a jump or temporally as close as possible to a jump of the time display member and,

[0065] - optionally, determining a position of the time display member associated with this first date. Method according to proposal 25, characterized in that the data processing step comprises:

[0066] - the determination and selection of at least two images from the first series of images taken at the time of a jump or temporally as close as possible to a jump of the time display organ, and

[0067] - determining a first date (Ttic) associated with the jump time of the time display member by calculation using the dates of the taking of the at least two images, in particular by determining the time of starting the movement of the time display member or the time of stopping the movement of the time display member or the time at which the speed of the display member is maximum, and,

[0068] - optionally, determining a position of the time display member associated with this first date. Method according to proposal 25, characterized in that the data acquisition step comprises acquiring an image of the time display member for a period during which it occupies two successive stable positions and in that the data processing step comprises:

[0069] - the determination of a first date (Ttic) associated with the instant of jump of the time display member, between the two successive stable positions, by calculation by analyzing the apparent intensities of the display member on the image in the two successive stable positions, and,

[0070] - optionally, determining a position of the time display member associated with this first date. Method according to one of proposals 23 to 28, characterized in that the data acquisition step comprises acquiring a second series of images of the time display member, in particular distinct from the first series of images, the second series of images including two separate images taken from the data acquisition step relating to the operation of the watch movement (100) or the timepiece (200). Method according to proposal 29, characterized in that the acquisition of the second series of images of the time display member is carried out over a period during which the time display member is in several successive stable positions.Method according to proposition 30, characterized in that the data processing step comprises identifying images from the second series of images taken while the time display member is in motion and / or on which the position of the time display member cannot be correctly identified, and excluding these images from the second series of images. Method according to one of propositions 29 to 31, characterized in that the data processing step comprises determining a second or second positions of the time display member associated with the images from the second series of images. Method according to one of propositions 29 to 32, characterized in that the data processing step comprises using a second date or second dates (Ts) associated with the taking of the images from the second series of images.Method according to proposition 33, characterized in that the data processing step comprises the calculation of a third date or dates (Tref) associated with a jump of the display member preceding or following the second date or dates (Ts). Method according to proposition 34, characterized in that the data processing step comprises a rate calculation and / or a state calculation using the third jump date(s) (Tref) or at least one jump instant deduced from the third date(s) (Tref). Device (10) for chronometric control or chronometric certification of a timepiece (200) or a watch movement (100), comprising hardware elements (11, 12, 13, 14, 15) and / or software implementing the method according to one of propositions 23 to 35.Method for producing or adjusting a timepiece (200) or a watch movement (100), the method comprising a step of implementing the chronometric control method according to one of propositions 23 to 35. Method for producing or adjusting according to proposition 37, the method comprising at least one adjustment step, in particular an adjustment step dependent on a rate deviation between a target value and a measured value. Timepiece (200), in particular a wristwatch, or watch movement (100) obtained by implementing the method according to one of propositions 37 and 38.Computer program product downloadable from a communication network and / or recorded on a data medium readable by a computer and / or executable by a computer, characterized in that it comprises instructions which, when the program is executed by the computer, lead the latter to implement the method according to any one of propositions 23 to 35. 41. Computer-readable recording medium (15) comprising instructions which, when executed by a computer, lead the latter to implement the method according to any one of propositions 23 to 35.

[0071] 42. Signal of a data carrier, carrying the computer program product according to proposition 40.

[0072] The attached drawings represent, by way of example, a timepiece according to the invention and illustrate phenomena on which the methods according to the invention are based.

[0073] Figure 1 is a representation of a timepiece according to the invention.

[0074] Figure 2 is a graph illustrating the standard error of a timing control method as a function of the time interval between two state measurements.

[0075] Figure 3 is a representation illustrating the principle of a mode of execution of the chronometric control method according to the invention.

[0076] Figure 4 is a schematic representation of one embodiment of a timing control device.

[0077] An embodiment of a timepiece 200 is described below in detail with reference to FIG. 1. The timepiece 200 is for example a watch, in particular a wristwatch. The timepiece 200 comprises a watch movement 100, on which a dial 50 is advantageously fixed. The watch movement is intended to be mounted in a timepiece case or box in order to protect it from the external environment. The watch movement 100 may be a mechanical watch movement, in particular an automatic watch movement, or a hybrid watch movement. The watch movement 100 comprises a frame and a regulating system. The regulating system comprises an oscillator and an escapement system, such as for example a Swiss lever escapement.

[0078] The oscillator comprises an inertial element, such as a balance wheel, and a return spring, such as a hairspring.

[0079] The timepiece also comprises time display elements 1, 2, 3, such as a second hand 1, a minute hand 2 and an hour hand 3. These display elements cooperate for example with markers and / or markings, such as a limb, preferably graduated, and / or one or more indexes and / or a railway, on the dial 50 to indicate the time.

[0080] A method of carrying out a time control process is described below. It implements a time control device which can be used in particular in production.

[0081] The timing control device includes:

[0082] - a camera capable of acquiring a photo or a series of photos, and

[0083] - processing means implementing a computer program capable of determining the angular positions of the different hands using the different available markers (position of the center, possibly position of certain markings or indexes).

[0084] Assuming that the uncertainty in the reference time is negligible, the measurement error G for a rate measurement made between two state measurements spaced by a time AT (in hours) is given by: o(AT)= 2x24xoPE / AT equation (1) with GPE the uncertainty in the measurement of the state (uncertainty in the position of the seconds hand). The jerky movement of the seconds hand causes, for the example of a watch equipped with an oscillator with a frequency of 4 Hz, a jerky movement at 0.125 s and a dispersion on the state of standard deviation GPE=0.125 / 12 1 / 2= 0.036 s. Figure 2 illustrates the influence of the time between AT state captures on the accuracy of the rate measurement o(AT), taking as an example GPE = 0.036 s as shown below.

[0085] Thus, for a measurement duration of 24 hours as for the measurement of the diurnal rate at the COSC, we obtain ao(24h)=0.045 s / d by exclusively considering the source of uncertainty coming from the jerky movement of the seconds hand. On the other hand, the same calculation applied to a measurement of the rate over 4 hours gives o(4h)=0.27 s / d, which becomes significantly more problematic. This may result in insufficient measurement capability for certain criteria, depending on the measurement protocols used (duration between state measurements, for example).

[0086] It therefore appears necessary to reduce the measurement error. It is proposed to reduce the error by precisely determining the instant of the jump of the seconds hand corresponding to the displayed time. The angle swept during one second by the hand is 6°, and the angle covered by this same hand during an alternation of the balance-spring oscillator depends on the frequency of said oscillator. This angle is for example 0.75° for an oscillation frequency of the balance-spring of 4 Hz. It then appears interesting to be able to determine the precise instant of the jump of the hand and to associate it with a position of the hand determined on an image, rather than taking the instant of the image capture as the time corresponding to the position of the hand. More generally, the seconds hand could for example be called a time display organ, namely participating in the display of the time or a schedule.This time display organ is integral with or mounted in derivation of a mobile regulated by the regulating system, in particular the oscillator, of the movement or of the timepiece. The jump of the time display organ is an unstable transient phase between two successive stable positions of the time display organ. Between two successive jumps, the time display organ remains, in each stable position, for substantially half an oscillation period of the oscillator of the watch movement. In other words, the jump is a sudden movement of displacement of the display organ, in particular a sudden movement of displacement of the display organ from one position to a following position. The duration of the assembly:.

[0087] - a jump phase, and

[0088] - a phase of maintaining the time display member in a stable position immediately preceding the jump phase or immediately following the jump phase is called the period of movement of the time display member.

[0089] An advantageous embodiment of the control method comprises on the one hand a determination of the position of the seconds hand on an image or on several images selected from a series of images of the dial, and on the other hand a precise detection of the instant of the jump of the hand so as to calculate the precise instant of the jump of the hand. In other words, the embodiment of the control method comprises, in addition to a step of acquiring data relating to the operation of the watch movement 100 or the timepiece 200, a step of processing the data so as to determine a jump instant of a time display member 1, in particular a seconds hand 1, of the watch movement 100 or the timepiece 200.

[0090] Thus, the method makes it possible to dissociate the measurement of the position of the needle and the determination of the instant of the jump by which the needle arrives in this position (or, according to other conventions, by which the needle leaves this position). This also makes it possible to capture or choose an image for which the needle is stationary during the shooting, that is to say acquired between two jumps of the needle. This approach, in association with a good time base (standard clock or reference clock), allows state measurements of remarkable precision.

[0091] In the embodiment of the method, there are several ways of overcoming the uncertainty linked to the jerky movement of the seconds hand, such as those indicated below. Preferably, the instant of a hand jump Ttic can be determined optically, for example by acquiring a first series of images. The first series of images is thus captured with an acquisition frequency much higher than the hand jump frequency, for example 80 or 160 Hz for a hand jump frequency of 8 Hz, over a duration of at least one period of movement of the hand. The instant of the jump is found by comparing the successive images. The acquisition frequency of the images of the first series of images is decisive for the time measurement resolution.In this hypothesis, the data acquisition step may comprise the acquisition of a first series of images of the time display member, this acquisition being for example carried out at a frequency f1 at least 10 times higher or at least 20 times higher than the jump frequency fs of the time display member.

[0092] In a first approach, the data processing step includes:

[0093] - the determination and selection of at least one image from the first series of images taken at the time of a jump or temporally as close as possible to a jump of the time display organ, and

[0094] - the determination of a first date Ttic associated with the instant of the jump of the time display member, such as being for example the date of the taking of at least one image of the first series of images taken at the moment of a jump or temporally closest to a jump of the time display member and,

[0095] - optionally, determining a position of the time display device associated with this first date. In other words, in this first approach, the data processing step may include:

[0096] - the determination and selection of at least two images from the first series of images taken at the time of a jump or temporally as close as possible to a jump of the time display organ, and

[0097] - determining a first date (Ttic) associated with the jump time of the time display member by calculation using the dates of the taking of the at least two images, in particular by determining the time of starting the movement of the time display member or the time of stopping the movement of the time display member or the time at which the speed of the display member is maximum, and,

[0098] - optionally, the determination of a position of the time display organ associated with this first date.

[0099] The data processing step comprises, for example, processing in which the successive images of the first series of images are subtracted pixel by pixel for each pair of successive images, then the standard deviation of this difference is calculated and the maximum value of this standard deviation is sought over the entire first series of images to determine the instant of the jump of the seconds hand. This instant Ttic can be defined as being the date of the first image of the pair of images having led to the maximum value of this standard deviation, or the date of the second image, or an average of these dates, or any other date determined by interpolation and / or weighting from the different images of the first series of images.

[0100] In practice, it is possible to estimate the needle speed (by comparing successive images) and to perform an interpolation to determine the moment when the needle speed is maximum. To do this, it is possible:

[0101] - calculate the differences between successive images two by two, and

[0102] - interpolate around the greatest difference to determine the instant when the speed is greatest, it being understood that the greater the difference between two successive images, the greater the speed of the needle.

[0103] The determination of the time of the Ttic jump can be advantageously carried out by considering more than two images, because the duration of the jump can be greater than the time between two successive images, depending on the chosen acquisition frequency.

[0104] The needle position may be blurred in the image corresponding to Ttic. In another case, the moment of the jump may occur not during an image capture, but between two images. In such a case, it is advantageous to use an interpolation and / or weighting technique from the different images of the first series of images. With this in mind, the data processing step may include:

[0105] - the determination and selection of at least one first image from the first series of images taken before a jump and preferably temporally as close as possible to the jump of the time display organ, and

[0106] - the determination and selection of at least one second image from the first series of images taken after the jump and preferably temporally as close as possible to the jump of the time display organ, and

[0107] - determining the date Ttic associated with the jump time of the time display device by calculation using the date of the first image capture and the date of the second image capture, in particular by interpolating the date Ttic associated with the jump time of the time display device from the date of the first image capture and the date of the second image capture, in particular by taking an average of the date of the first image capture and the date of the second image capture.

[0108] Alternatively, the instant Ttic of the jump can correspond to:

[0109] - in the “middle” of the jump, corresponding for example to the moment when the needle speed is at its maximum,

[0110] - at the start of the jump (the moment the needle starts moving, for example),

[0111] - at the end of the jump (instant of complete stop of the needle, for example), or - to any other definition; provided that this definition is used consistently throughout the process.

[0112] Furthermore, the position of the hand, corresponding to the instant Ttic, could be determined on another image than that(s) used to determine the instant of the jump, in particular on another image allowing the seconds hand to be clearly distinguished.

[0113] It may be interesting to consider separately:

[0114] - the images of a first series of images allowing the instant of the Ttic jump to be determined (on which the position of the second hand can be difficult to determine precisely), and

[0115] - another image allowing the position of the needle associated with this jump to be determined precisely (but not providing any element allowing the precise date of the moment of the jump).

[0116] It is also possible to determine the times of the hand jumps by means of a series of images acquired by a standard camera, provided that the capture of these images is not synchronized with the hand jumps, in particular by the acquisition of a first series of images, for example 10 or 20 or 50 images taken over one minute, regularly or periodically, or alternatively at randomly distributed acquisition times. This approach has the advantage of being able to be applied with a standard camera, without high-frequency acquisition. In this variant, the data acquisition step may comprise the acquisition of a first series of images of the time display member, this acquisition being for example carried out for a duration such that the time display member is in several successive stable positions, in particular in more than two successive stable positions.It is also possible to use a single image with a shutter speed (exposure time) corresponding to the duration of an alternation (or a period of movement of the hand), which will include a blurred image of the hand, because the hand will have moved during the acquisition of the image. With an image analysis on the gray levels or the intensity of the light on a segment of the hand, one can deduce the time spent in the position before the jump and in the position after the jump, respectively, and thus deduce the moment of the jump. Thus, the data acquisition step may comprise the acquisition of an image of the time display organ during a period during which it occupies two successive stable positions, and the data processing step may comprise:

[0117] - the determination of a first date Ttic associated with the instant of jump of the time display organ, between the two successive stable positions, by calculation by analyzing the apparent intensities of the display organ on the image in the two successive stable positions.

[0118] It is also possible to use a stroboscope whose frequency is set close to the frequency of the hand movement. Positions of the second hand spaced one step apart (the duration of which corresponds to that of an alternation of the oscillator) are then detected up to the point where the jump and the lighting are synchronized, which is characterized by a hand appearing "blurred" because it is in movement during the flashes of the stroboscope. It is also possible to use a single long video sequence (over several seconds) on which the instants of hand jump would be detected.

[0119] With a first series of images acquired at high frequency, the residual uncertainty is of the order of half the time between two images, and will be better if an interpolation is carried out between the images. During certain tests, in particular by determining the instant when the needle has a maximum speed by means of an interpolation, residual standard deviations (repeatability) of less than 1 ms on the instant of the needle jump (modulo the average time interval between two jumps) were obtained. As an alternative to optical methods, the instant of a needle jump can also be determined acoustically. It is possible to capture an acoustic "ticking" signal whose period corresponds to the duration of the escapement's alternations (0.125 s for an oscillator with a frequency of 4 Hz).Thus, in such a hypothesis, the data acquisition step comprises the acquisition of acoustic data and the data processing step comprises the determination of a first date Ttic associated with the instant of jump of the time display member. This first date Ttic can thus be determined by processing the acoustic data. Other approaches, such as detecting the instant of the hand jump magnetically, or by laser vibrometry, or by any other suitable measuring means, are also conceivable.

[0120] Advantageously, the data acquisition step comprises the acquisition of a second series of images of the time display member distinct from the first series of images. More preferably, the acquisition of the second series of images of the time display member is carried out over a period during which the time display member is in several successive stable positions.

[0121] As mentioned above, the reference time Ttic is the instant at which the detected jump begins (at which the hand leaves its rest position), or the instant in the middle of the jump (maximum speed of the hand), or the instant at which the jump ends. Since the hand jump is generally very regular, it is possible to extrapolate it (on the basis of the nominal frequency and / or on the basis of the average jump angle as determined by the movement design) over a few seconds for the case where the acquisition of the signal for the precise determination of the hand position is not done simultaneously with the determination of the hand jump instant, and / or if it is carried out by different means (for example, it is carried out by two different cameras, or by the same camera but with two different settings - in terms of acquisition frequency, area of ​​the dial captured, etc.).Knowing the instant of the hand jump (and the nominal hand jump frequency), it is desirable to trigger the taking of an image of the dial for the precise determination of the position of the seconds hand during the periods when the hand is stationary, i.e. between the jumps. Alternatively, it is possible to take several successive images (two or more) during a duration of one period of movement of the hand (or several periods), then to choose, on the basis of the instant of the detected jump, the image on which the hand is stationary. Thus, the data processing step may comprise an identification of images from the second series of images taken while the time display member is in motion and / or on which the position of the time display member cannot be correctly identified, and the exclusion of these images from the second series of images.

[0122] The calculation of the reference time Tref (third date) is defined below and with reference to figure 3, with

[0123] - Ttic (first date), the instant of the jump of the second hand determined on the basis of the first series of images S1 Tr_0...Tr_x-2, Tr_x-1, Tr_x, Tr_x+1 ...Tr_i acquired at an acquisition frequency f_hf,

[0124] - Ts (second date), the (measured) instant of taking the image of the second hand (in the case of figure 3, before the first series of images S1).

[0125] We then calculate the number of jumps (or "tics") NbT (real number not necessarily whole) between the image acquired at time Ts and the instant of the detected jump Ttic by:

[0126] NbT=fsx(Ttic-Ts) where fs is the jump frequency of the second hand.

[0127] Tref is the instant of the jump preceding the first frame of the second hand and is obtained as follows:

[0128] Tref=Ts+(NbT-[NbTl) / fs where [NbT] is the upper integer part of the number of needle jumps ("tics"), i.e. the number of needle jumps rounded up to the nearest whole number.

[0129] The number of jumps that took place between the image of the second series S2 corresponding to Ts, used for the precise determination of the position of the hand, and the time of the jump Ttic detected during the first series of images was thus calculated, on the basis of the nominal frequency of the oscillator, and the time Tref of the jump of the seconds hand that preceded the image corresponding to Ts was deduced from this. This reference time Tref is then associated with the position of at least the seconds hand on the image corresponding to Ts and is used for the calculation of the rate and / or the state.

[0130] The data processing step may thus include the use of a date or dates Ts associated with the taking of the second series of image(s), acquired before, during or after the first series of images.

[0131] The data processing step advantageously comprises determining a second or second positions of the time display member associated with the images of the second series of images.

[0132] The data processing step preferably comprises the calculation of one or more reference dates Tref associated with a jump of the display device preceding, or following, the date or second dates Ts.

[0133] In the case where it turns out that the image selected for determining the precise position of the hand was taken during or just after a hand jump (as determined from the time of the jump during the first series of images), and therefore that the hand is blurred, this image is ignored and the process is repeated. An alternative is to capture several images, one of which definitely includes a stationary hand, for example with two images spaced apart by half a period of movement of the hand (0.0625s for an oscillator frequency of 4Hz), or by 1.5 periods of movement of the hand (0.1875s) or by a little more than the duration of a jump. Thus, more generally, the second series of images of the time display organ can comprise at least two images taken separated by a time:

[0134] - greater than n periods of movement of the time display organ increased by a jump time of the time display organ, and

[0135] - less than n+1 periods of movement of the time display member reduced by a jump time of the time display member, with n an integer. For example, n=0 or n=1 or n=2 or n=3. Another alternative is, on the basis of the determination of the time of the jump, to choose a posteriori in a targeted manner an image which will include a stationary hand for the determination of the position, for example by acquiring an image at (n+0.5) periods of movement of the hand after the time of the detected jump Ttic. Since the time of a jump is known precisely, the acquisition of an image between two jumps is facilitated. Thus, more generally, the second series of images of the time display member can comprise (i) a single image capture or (ii) at least one image capture separated from the time of the jump of the time display member (1) by a time:

[0136] - greater than n periods of movement of the time display organ increased by a jump time of the time display organ, and

[0137] - less than n+1 periods of movement of the time display organ reduced by a jump time of the time display organ, with n an integer. For example, n=0 or n=1 or n=2 or n=3.

[0138] The jump time is the duration during which the display organ moves abruptly between two successive stable positions.

[0139] Alternatively, the reference clock can be directly and permanently linked to a recognized metrological reference clock, in particular by implementing a PTP (Precision Time Protocol). This makes it possible, among other things, to know at all times the uncertainty on the date of the image capture, which is not possible with a reference clock using a GPS signal for which the uncertainty is not known.

[0140] In a variant of the control method, the instant of the hand jump is detected by taking high-frequency images (first series of images). The step of acquiring data relating to the operation of the watch movement 100 or the timepiece 200 can then comprise two steps:

[0141] - an image of the complete dial is taken (second series of images) on which the angular position of at least the second hand will be determined in relation to the reference axis (midday) of the part, then

[0142] - a few seconds later, a first series of images is taken at the chosen frequency, for example 10 times or 20 times the hand jump frequency, over a restricted area around the axis of rotation of the seconds hand, over a duration covering at least one hand jump. The duration of the first series of images is preferably chosen to be slightly greater (for example 20% greater) than the period of movement of the seconds hand.

[0143] The claimed invention is not limited to the modes and variants described above. In addition or as a variant, one can also:

[0144] - Measure or calculate the instant of the jump before taking the first image which is used to determine the position of the needle.

[0145] - Determine the position of the seconds hand on different successive images associated with the same detection of the instant of the hand jump, so as to reduce the measurement dispersion.

[0146] - Determine the position of the seconds hand on different successive and independent state measurements, so as to reduce measurement dispersion.

[0147] - If the hand jump is detected optically, combine the detection of the jump and the position of the seconds hand on the same series of images, choosing for the position of the hand an image where the hand is stationary. - Take, before any measurement, a series of photos at different distances from the dial, so as to have clear images of the different hands and the different elements of the dial. Indeed, the differences in altitude between these different elements can lead to blurring which is detrimental to processing.

[0148] The solution allows the measurement of the needle position and the time of the jump to be separated. This allows the following to be precisely determined:

[0149] - on the one hand, a needle position, and

[0150] - on the other hand, the precise jump moment associated with this position.

[0151] These determinations are made on the basis of independent measurements, which offers better precision than simply taking a reference time at the time the image is taken, which is used to measure the position of the hands.

[0152] With this approach, it is possible to obtain higher precision on daytime running measurements, or conversely to shorten certain measurements for equivalent precision, for example to carry out a test comparable to that of the ISO3159 standard but with shorter intervals between state measurements, or to make several measurements per day on watches worn in real situations, on the wearer's arm.

[0153] The described solution allows for the implementation of a precise determination of the instant of the jump of the second hand, which is applicable regardless of the oscillator frequency, in particular for a frequency of 3 Hz or 3.5 Hz or 4 Hz or 5 Hz or 6 Hz or 8 Hz or 10 Hz. The gain in precision makes it possible to consider new measurement approaches, such as shorter measurement times and / or measurement times that allow greater precision.

[0154] In general, the gain in precision is necessary:

[0155] - if the time between status readings decreases (decrease in measurement time or need for measurement efficiency), and / or

[0156] - if the requirement for accuracy increases (reduction of the permissible tolerance interval for walking).

[0157] This document describes the approaches and solutions developed to reduce uncertainty in rate measurements by state capture. Solutions are provided to reduce the various uncertainties, notably by precisely determining the instant of the jump of the seconds hand. The solution significantly improves the accuracy of the state.

[0158] Previously, it was common for the reference time to correspond to an instant of image capture. However, with the solutions described, it appears that it is possible to adopt an alternative approach to increase measurement accuracy (in particular by determining the instant of the jump, and optionally acquiring several images).

[0159] The chronometric control process can be used on various equipment and on various watch configurations (small diameter watches, chronographs, without constraints on dial designs).

[0160] The invention also relates to a method for producing or adjusting the timepiece 200 or the watch movement 100. The method comprises a step of implementing the chronometric control method described previously.

[0161] The production or adjustment method preferably comprises at least one adjustment step, in particular an adjustment step dependent on a deviation in rate between a target value and a value measured or determined by implementing the chronometric control method described above. The invention also relates to the watch movement 100 or to the timepiece 200 obtained by implementing the adjustment method which is the subject of the invention.

[0162] The invention also relates to the device 10 for chronometric control or chronometric certification of a timepiece 200 or a watch movement 100. The device 10 comprises hardware elements 11, 12, 13, 14 and / or software implementing the methods described previously.

[0163] In one embodiment of the device, shown schematically in Figure 4, the hardware elements may include in particular:

[0164] - a camera 11 or more generally a data acquisition element,

[0165] - a reference clock 12,

[0166] - a logical processing unit 13,

[0167] - a 15 memory, and

[0168] - possibly a microphone or other measuring instrument 14.

[0169] The hardware elements may be portable. In particular, the entire hardware element or the device may be portable.

[0170] The device may be or include:

[0171] - a telephone, and / or

[0172] - a smartphone, and / or

[0173] - a tablet, and / or

[0174] - a computer like a laptop.

[0175] Regardless of the execution mode or variant, it is possible to carry out several successive determinations in order to improve the measurement accuracy and / or reduce the measurement error, for example several successive determinations of a first date (Ttic) associated with the jump instant of the time display member and / or to use several images of the second series of images of the time display member, these images showing the same position of the time display member and / or showing several successive stable positions of the time display member.

[0176] Whatever the execution mode or variant, the step of acquiring data relating to the operation of the watch movement 100 or the timepiece 200 may comprise the acquisition of a video signal or a video stream (produced by the camera) associated with data from the reference clock making it possible to date all the images or some of the images of the video signal or the video stream.

[0177] Throughout this document, unless otherwise specified, the ordinal numeral adjectives "first", "second", "third" do not have a temporal meaning, but a distinctive meaning.

[0178] Preferably, whatever the embodiment or variant, according to the invention, it is understood, from what has been described previously, that a jump instant of a time display member 1 is determined by exploiting acoustic and / or magnetic and / or optical data from physical phenomena caused by the displacement movements of the display member.

[0179] According to the invention, a method of chronometric control or chronometric certification may comprise:

[0180] - a determination of the position of the hands in order to determine the time displayed tdis,

[0181] - a determination of the instant tREF at which this time tdis is displayed using a solution for determining a jump instant of a time display device 1, the date of this instant being given by the reference clock.

[0182] According to the invention, a method of chronometric control or chronometric certification may comprise a calculation of a chronometric state by the difference between the displayed time and the reference time: state = tdis-tREF. According to the invention, a method of chronometric control or chronometric certification may comprise a calculation of the rate by the difference between two chronometric states taken at two instants spaced apart by a certain time (for example 24 hours).

Claims

Claims:

1. Method for chronometric control or chronometric certification of a watch movement (100) or a timepiece (200), in particular a method for calculating a chronometric state, comprising: - a step of acquiring data relating to the operation of the watch movement (100) or the timepiece (200), - a step of processing the data so as to determine a jump instant of a time display member (1), in particular a second hand (1), of the watch movement (100) or of the timepiece (200).

2. Method according to claim 1, characterized in that the data acquisition step comprises the acquisition of acoustic and / or magnetic and / or optical data, and in that the data processing step comprises the determination of a first date (Ttic) associated with the jump instant of the time display member.

3. Method according to claim 1 or 2, characterized in that the data acquisition step comprises the acquisition of a first series of images of the time display member, this acquisition being in particular: - carried out at a frequency (f1) at least 10 times higher or at least 20 times higher than the jumping frequency (fs) of the time display organ, and / or - carried out for a duration such that the time display organ is in several successive stable positions, in particular in two successive stable positions.

4. Method according to the preceding claim, characterized in that the data processing step comprises: - the determination and selection of at least one image from the first series of images taken at the time of a jump or temporally as close as possible to a jump of the time display organ, and - the determination of a first date (Ttic) associated with the time display member's jump time as being the date of taking at least one image of the first series of images taken at the time of a jump or temporally as close as possible to a jump of the time display member and, - optionally, the determination of a position of the time display organ associated with this first date.

5. Method according to claim 3, characterized in that the data processing step comprises: - the determination and selection of at least two images from the first series of images taken at the time of a jump or temporally as close as possible to a jump of the time display organ, and - determining a first date (Ttic) associated with the jump time of the time display member by calculation using the dates of the taking of the at least two images, in particular by determining the time of starting the movement of the time display member or the time of stopping the movement of the time display member or the time at which the speed of the display member is maximum, and, - optionally, the determination of a position of the time display organ associated with this first date.

6. Method according to claim 3, characterized in that the data acquisition step comprises the acquisition of an image of the time display member for a period during which it occupies two successive stable positions and in that the data processing step comprises: - the determination of a first date (Ttic) associated with the instant of jump of the time display member, between the two successive stable positions, by calculation by analyzing the apparent intensities of the display member on the image in the two successive stable positions, and, - optionally, the determination of a position of the time display organ associated with this first date.

7. Method according to one of the preceding claims, characterized in that the data acquisition step comprises the acquisition of a second series of images of the time display member, in particular distinct from the first series of images.

8. Method according to the preceding claim, characterized in that the acquisition of the second series of images of the time display member comprises at least one image capture separated from the instant of jump of the time display member (1) by a time: - greater than n periods of movement of the time display organ increased by a jump time of the time display organ, and - less than n+1 periods of movement of the time display member reduced by a jump time of the time display member, for example a time of n+0.5 periods of movement of the time display member, with n an integer.

9. Method according to claim 7, characterized in that the acquisition of the second series of images of the time display member comprises at least two image captures separated by a time: - greater than n periods of movement of the time display organ increased by a jump time of the time display organ, and - less than n+1 periods of movement of the time display member reduced by a jump time of the time display member, for example a time of n+0.5 periods of movement of the time display member, with n an integer.

10. Method according to claim 7 or 9, characterized in that the acquisition of the second series of images of the time display member is carried out over a period during which the time display member is in several successive stable positions.

11. Method according to the preceding claim, characterized in that the data processing step comprises the identification of images from the second series of images taken while the time display member is in motion and / or on which the position of the time display member cannot be correctly identified, and the exclusion of these images from the second series of images.

12. Method according to one of claims 7 to 11, characterized in that the data processing step comprises determining a second or second positions of the time display member associated with the images of the second series of images.

13. Method according to one of claims 7 to 12, characterized in that the data processing step comprises the use of a second date or second dates (Ts) associated with the taking of the images of the second series of images.

14. Method according to claim 13, characterized in that the data processing step comprises the calculation of a third date or third dates (Tref) associated with a jump of the display member preceding or following the second date or second dates (Ts).

15. Method according to the preceding claim, characterized in that the data processing step comprises a walking calculation and / or a state calculation. using the third jump date(s) (Tref) or at least one jump time deduced from the third date(s) (Tref).

16. Device (10) for chronometric control or chronometric certification of a timepiece (200) or a watch movement (100), comprising hardware elements (11, 12, 13, 14, 15), in particular a data acquisition element (11, 14) and a data processing logic unit (13), and / or software implementing the method according to one of the preceding claims.

17. Method for producing or adjusting a timepiece (200) or a watch movement (100), the method comprising a step of implementing the chronometric control method according to one of claims 1 to 15.

18. Production or adjustment method according to the preceding claim, the method comprising at least one adjustment step, in particular an adjustment step dependent on a deviation between a target value and a measured value.

19. Timepiece (200), in particular wristwatch, or watch movement (100) obtained by implementing the method according to one of claims 17 and 18.

20. Computer program product downloadable from a communications network and / or recorded on a data medium readable by a computer and / or executable by a computer, characterized in that it comprises instructions which, when the program is executed by the computer, lead it: - to implement the method according to any one of claims 1 to - to control the device (10) for chronometric control or chronometric certification according to claim 16 to implement the method according to any one of claims 1 to 15.

21. Computer-readable recording medium (15) comprising instructions which, when executed by a computer, cause the latter to implement the method according to any one of claims 1 to 15.

22. Signal of a data carrier, carrying the computer program product according to claim 20.

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