Method for testing a display kinematic chain in a watch or watch movement downstream of its oscillator

Abstract

One aspect of the invention relates to a method for testing the display of a dial, wherein the dial is kept in continuous operation for 24 hours, at an initial instant, an initial optical image of the hands is acquired with reference to a fixed point; at least 24 hours later, at a final instant measured on a reference clock, a final optical image of the hands is acquired with reference to the fixed point; the position of the hands at the initial instant and the position of the hands at the final instant are determined by means of a visual recognition device; the difference between the reference position on the reference clock and the actual position of the hands is calculated and the measured deviation of the state is displayed.

Description

Technical Field

[0001] This invention relates to a method for testing the display motion chain downstream of the oscillator of a watch or watch head, which is performed simultaneously with tests commonly performed in the watchmaking industry at a set of test stations.

[0002] This invention relates to the field of watch timekeeping and condition testing. Background Technology

[0003] To ensure a certain level of timekeeping accuracy, it is crucial to conduct timekeeping tests before completing the watch head or timepiece. In mechanical watches, these tests focus on the quality of the oscillator. However, the display accuracy involved in condition testing relates not only to the oscillator (or regulator) but also to the power mechanism, the display setting mechanism, and all gear trains (especially the final gear train and the drivers of the indicators, particularly the hands). Any backlash in the gears will cause visual measurement inaccuracies in these indicators or hands. Slippage of an indicator or hand on its pivot is usually much greater than measurement inaccuracies. Finally, transmission error (count of teeth) is one of the most serious cases; the loss of even a single tooth can result in a loss of more than 100 seconds per day.

[0004] Therefore, the performance of the best oscillator can be masked by purely mechanical or kinematic defects: out-of-roundness, lack of lubrication, damaged or missing teeth, gear backlash, slippage on the pivot, pointer friction, or other defects.

[0005] Therefore, it is crucial to perform display synchronization tests on watch heads or watches, including those with mechanical movements. Furthermore, traditional display tests at the set time are typically designed to be independent of the display movement during watch operation.

[0006] Since the kinematic chain is tested separately, the state of the meter or meter head can be measured and tested without a meter or meter head display and therefore only on the speed controller. Summary of the Invention

[0007] Therefore, the present invention proposes to perform display synchronization testing in order to avoid delivering clocks containing any of these defects.

[0008] Therefore, the present invention relates to a method for testing a display motion chain located downstream of an oscillator of a meter or meter head, the method being performed synchronously with testing at a set of test stations, wherein the timekeeping status of the meter or meter head is simultaneously measured by acquiring the optical state of the pointer and performing continuous or quasi-continuous acoustic measurements at the set of test stations, the meter or meter head being maintained to run continuously for at least 24 hours of measurement time TM by: providing the meter or meter head with an energy source that enables it to run continuously for at least the measurement time TM; or equipping the test stations with a winding and / or rocking device by winding or rocking the meter or meter head to restart it for at least the measurement time TM. Attached Figure Description

[0009] The objects, advantages, and features of the invention will become clearer from the following detailed description with reference to the accompanying drawings, in which:

[0010] Figure 1 This diagram illustrates a specific sequence of operations highly suitable for applying the present invention, wherein the operations are performed in parallel over time. The topmost line represents the previous operation; the following lines represent a series of operations within the watch movement, including magnetic performance testing, acoustic testing of daily timekeeping accuracy, and water resistance testing. The bottommost line relates to optical testing, and the middle section provides details of the initial acoustic measurement of daily timekeeping accuracy, including a series of measurements performed at different temperatures and at various standard timing positions.

[0011] Figure 2 A schematic diagram illustrating the timestamps of the movement's ticking sound, including the first and last release times, the impact time, and the descent time. Detailed Implementation

[0012] This invention relates to a method for testing the display motion chain downstream of the oscillator of a meter or meter head, by simultaneously measuring the timekeeping status of the meter or meter head through acquiring optical images of the pointer at a set of test stations and performing continuous or quasi-continuous acoustic measurements.

[0013] According to this method, depending on the required measurement accuracy, the meter or meter head needs to operate continuously for at least 24 hours of measurement time TM, ideally for several days. The method to maintain continuous operation is either to provide the meter or meter head with enough energy to operate for at least the required measurement time TM (i.e., at least 24 hours), or to equip the test station with a winding and / or rocking device to wind or rock the meter or meter head, thus ensuring at least 24 hours of measurement time TM. Alternatively, both methods can be used simultaneously: providing the meter or meter head with a certain power reserve, and equipping the test station with a winding and / or rocking device to wind or rock the meter or meter head, thus maintaining the measurement time TM at least 24 hours.

[0014] At the initial time t0, at a fixed point on the reference table or head and / or a fixed point on the tool carrying the reference table or head, at least one initial optical image of the pointer of the table or head is acquired.

[0015] After acquiring the initial optical image, the meter or meter head is immediately placed in a device with a reference clock and a tick detection system to perform continuous or quasi-continuous acoustic measurements of the speed controller over the entire time t.

[0016] Therefore, by performing continuous or quasi-continuous acoustic measurements on the oscillator or speed controller in the meter or meter head between the initial optical image acquisition and the final optical image acquisition, the time deviation can be determined.

[0017] After the measurement time TM ends, the timekeeping is acoustically evaluated by counting the number of ticks corresponding to the elapsed time.

[0018] Between two state image acquisitions, the table may be subjected to various potential stresses that could affect its timekeeping, such as dynamic motion, static position, temperature, and humidity.

[0019] Furthermore, at the final time t0+t measured on the reference clock, at least one final optical image of the pointer of the reference clock or meter is acquired at a fixed point on the reference clock or meter head and / or a fixed point on the tool. The positions of these pointers at the initial time t0 and the final time t0+t are determined by a vision recognition device equipped at the test station. The difference between the reference position relative to the reference clock and the actual position of the pointer is calculated, and the measured state deviation value is displayed.

[0020] Therefore, optical measurements can test the timing performance of the "power mechanism + oscillator" part and the display part of a watch, while acoustic measurements can only test the timing performance of the "power mechanism + oscillator" part of the movement.

[0021] To determine the synchronization of the display, the difference between the following two values ​​must be calculated: first, the timekeeping of the meter or meter head determined by acquiring the optical state of the display; and second, the timekeeping of the meter determined by acoustically measuring the ticking sound in a continuous or quasi-continuous manner. If the meter has no display problems, this difference will be close to 0, regardless of its oscillator performance.

[0022] It should be understood that this invention relates to comparing the counting time of an acoustic speed controller with the counting time of a display device. The length of this time only affects the accuracy of the required comparative measurement.

[0023] In an advantageous embodiment of the method, each optical measurement operation is performed by acquiring multiple images and averaging the pointer positions identified in each image to reduce measurement inaccuracies.

[0024] More specifically, according to this method, between the initial moment and the final moment, dynamic spatial movement, winding operation, resting at a standard timing position, or any other stress is applied to the watch or watch head, in accordance with the requirements of official standards such as ISO 3159 or internal standards and other standards.

[0025] More specifically, spatial movement is applied to the watch or watch head to perform a timekeeping test at a standard timing position and determine the timekeeping deviation value at said standard timing position; the timekeeping deviation value and the status deviation value are compared with internal specifications to allow or prohibit the subsequent manufacture of the watch or watch head.

[0026] More specifically, at the standard timing position, intermediate time checks are performed by partial or complete instantaneous or continuous acoustic measurements.

[0027] Furthermore, at least one intermediate test is performed at at least one intermediate time between the initial time and the final time, wherein, with reference to at least one intermediate optical image of the pointer of the fixed-point acquisition table or the head of the table, the pointer position at the initial time and the pointer position at the intermediate time are determined by a visual recognition device, the difference between the reference position relative to the reference clock and the actual position of the pointer is calculated, and the state deviation value measured at the intermediate time is displayed.

[0028] More specifically, between the initial moment and the final moment, under predetermined time periods, temperature, and humidity conditions, the watch or watch head is placed in an oven.

[0029] More specifically, the table or header is encapsulated and locked in a processing box (a transparent processing box is selected), and all operations performed on the table or header between the initial time (other than the initial time) and the final time are performed within this processing box.

[0030] Furthermore, at least one initial image is acquired before the table or table head is placed into the processing box, and at least one final image is acquired after the table or table head is removed from the processing box.

[0031] In one specific embodiment, the test method is applied to mechanical watches.

[0032] It should be noted that in the field of watchmaking, acoustic measurements usually refer to instantaneous measurements (generally 40 seconds); however, in this invention, in order to ensure that every tick of the watch is counted throughout the entire observation period between two visual state image acquisitions, these acoustic measurements are continuous or quasi-continuous.

[0033] The following describes in detail a specific, but not limiting, embodiment of the method according to the present invention.

[0034] The METAS N001 v 1.2 standard (new certification requirements for mechanical movements and watches resistant to a 1.5T (15,000G) magnetic field) is compatible with the photoacoustic measurement of watches and watch heads. More specifically, the technology employed is based on the following preparation: placing the watch or watch head in a universal acoustic test chamber compatible with the watch head, as described in documents such as EP3410234, EP3812847, EP22209439.3, CH001445 / 2022, EP22209441.9, and CH001404 / 2022. This technology achieves an accuracy of ±50 milliseconds / day. These acoustic test chambers are typically designed to accommodate ten or more watches or watch heads and are ideal for holding watches or watch heads in place.

[0035] Display synchronicity is tested through optical measurements of the state of the second and / or minute hands. In the "second hand + minute hand" test scheme, the display synchronicity test must last for approximately six days (at least 120 hours) to minimize measurement inaccuracies.

[0036] Figure 1 This illustrates a specific sequence of operations highly suitable for applying this invention. The topmost line represents a series of top operations R1, ..., Rn to maintain the watch's operation: a top operation is performed at the beginning of each cycle as required by the METAS N001 standard. The lines below represent a series of operations, namely, magnetic performance testing, daily timekeeping accuracy testing, and water resistance testing; the order and number of these operations can be varied without departing from the scope of this invention and complying with the METAS N001 standard requirements.

[0037] In preparation for meter testing according to METAS N001 standard requirements, the meter is placed in the aforementioned acoustic test box.

[0038] Preferably, each acoustic test box can hold a set of meters (e.g., ten); then these final timekeeping and condition tests are performed on the entire set of meters.

[0039] This series of operations is preferably performed using automation and robotics: each spatial processing operation is applied to the acoustic test chamber; all tests under controlled temperature, humidity, pressure or other conditions are performed on the entire test chamber.

[0040] The first test operation 10 is a daily timekeeping accuracy test PJ1: the acoustic test chamber is positioned in different spatial orientations. Inside the acoustic test chamber, a microphone (especially a piezoelectric microphone) in contact with the watch head is used to listen to the ticking sound of the watch and isolate the characteristic moments of the mechanical watch oscillator (release moment, impact moment, drop moment). These characteristic moments are common to Swiss lever escapement and coaxial escapement mechanisms, even if these moments do not completely correspond to the contact between the same surfaces. The temperature and position conditions of this first test operation 10 are in accordance with the requirements of METAS N001 standard.

[0041] After the first test operation, the following operations will be performed in sequence:

[0042] - Functional test operation in the magnetic field 20;

[0043] - Second timing test operation 30 (similar to the first test operation 10 above, and the temperature conditions are in accordance with the METASN001 standard requirements).

[0044] - Demagnetization operation 40;

[0045] - Third timing test operation 50 (similar to the first test operation 10 above, and the temperature conditions are in accordance with the METASN001 standard requirements).

[0046] - Fourth timing test operation 60 (similar to the first test operation 10 above, and the temperature conditions are in accordance with the METASN001 standard requirements).

[0047] - Power Reserve Test Operation 70 (Cycle 7 in METAS N001 Standard);

[0048] - After completing the above operations, conduct a waterproof test.

[0049] The optical tests are performed in parallel with the acoustic tests (shown by the bottom line in the diagram): the optical tests are advantageously performed while the meter is being processed to confirm or deny display synchronicity.

[0050] Synchronization is tested by acquiring optical images of the second and minute hands. Pointer optical recognition is achieved through a series of continuous measurements over a 60-second observation period, which eliminates optical imaging artifacts to determine the gain or loss in timekeeping between two states of the watch head or timepiece. During this period, the date is recorded for each image acquisition, and then a shape-matching algorithm is used to locate the position and orientation of the watch head or timepiece and identify the hands.

[0051] If the reference clock in each acoustic test box is calibrated before measurement, the technology used in the acoustic test box can be used for meter measurements with an accuracy of ±50 milliseconds / day, or even ±10 milliseconds / day.

[0052] The acoustic measurement and processing system and its usage are described in detail in paragraphs 0014 to 0021 and Figures 4 to 6 of document EP3812847. In summary, the purpose of this continuous acoustic measurement system is to timestamp the impact of the movement oscillator. The control unit processes these timestamps and measures the daily timekeeping accuracy of the meter within the acoustic test chamber.

[0053] Due to data volume and power consumption (processor computation), the signals corresponding to the meters installed in the acoustic test box (especially ten meters) need to be divided into multiple signal sequences in time. The number of active channels and the length of the signal sequences can be adjusted according to the onboard firmware. The duration of each signal sequence is at least 5 seconds to ensure that the algorithm completes self-configuration and achieves sufficient accuracy to detect the moment of impact: approximately 2 seconds are used to detect the noise threshold and frequency level, and approximately 3 seconds are used to accumulate enough data to estimate the impact moment and the moment of impact through the superposition method.

[0054] Subsequently, the onboard algorithm determines the timestamps of the tick impacts. At the start of each measurement sequence, the algorithm first classifies frequencies within the range of 2 Hz to 5 Hz in 0.5 Hz steps to detect frequencies, then detects the noise level within the silent zone to determine a threshold for detecting the release moment. The release of the tick is identified by threshold cross-validation. Since this information is the modulus of the movement frequency, the first and last releases must be retained. The drop and impact are timestamped by signal superposition. Therefore, to ensure the maximum amount of data required for superposition, these timestamps are generated only for the last few ticks. Figure 2 Solid lines represent the timestamps of ticks, and dashed lines represent the timestamps of tocks. Only the first and last ticks in each measurement sequence are shown. The duration of each measurement sequence is TH (e.g., 10 seconds), and the measurement sequences are independent of each other. For tick timestamps: t1 is the first release time, t2 is the last release time, t3 is the impact detection time, and t4 is the drop detection time; for tock timestamps: t5 is the first release time, t6 is the last release time, t7 is the impact detection time, and t8 is the drop detection time.

[0055] The validity of the acoustic measurements of daily time travel were verified by comparing them with optical measurements performed in the same manner using an acoustic test box. Observations showed that the acoustic and optical measurements converged relatively quickly (after approximately 24 hours).

[0056] By implementing this photoacoustic measurement method in parallel over 120 hours, the inaccuracy of the minute hand display synchronization measurement can be reduced to approximately 5 seconds per day, and the second hand to approximately 100 milliseconds per day, thereby ensuring reliable detection of potential display malfunctions.

[0057] A typical but non-limiting operating procedure includes the following steps:

[0058] - A. Place in the acoustic test box.

[0059] - B Kamijou

[0060] - C Let stand for 24 hours

[0061] - D Daily Timekeeping Accuracy Test 01

[0062] - E winding

[0063] - F Standard Preparation

[0064] - Functional testing in the G magnetic field

[0065] - H captures the hour and minute hand status at 0.

[0066] - I. Place in the acoustic test box

[0067] - J Daily Timekeeping Accuracy Test 02

[0068] - K demagnetization

[0069] - L Kamijou

[0070] - M Let stand for 24 hours

[0071] - N Daily timekeeping accuracy test 03

[0072] - O Kamijou

[0073] - P Let stand for 24 hours

[0074] - Q Daily Timekeeping Accuracy Test 04

[0075] - R Kamijou

[0076] - Let stand for 48 hours

[0077] - T Standard Preparation

[0078] - U Collects the hour and minute hand status at 0:00

[0079] - V Power Reserve Test

[0080] - W-related pointer synchronization test for acoustic signals

[0081] - X Waterproof Test

[0082] - Y Storage.

[0083] Specifically, in operations A to S, except for operations G and H, all other operations performed on the meter head are conducted within the acoustic test chamber; the meter head simultaneously experiences the motion applied by the meter shaker and is sent into the oven as planned. In short, this invention utilizes developed technical conditions: standards compatible with the visual and processing operations of magnetic field testing and acoustic test chambers, meeting the requirements of METAS N001, ensuring absolute safety during the testing cycle, requiring no human intervention, and avoiding any testing deviations.

Claims

1. A method for testing a display motion chain located downstream of an oscillator of a meter or meter head, the method being performed synchronously with tests at a set of test stations, wherein, The timekeeping status of the meter or meter head is simultaneously measured by acquiring the optical state of the pointer and performing continuous or quasi-continuous acoustic measurements at the set of test stations. The meter or meter head is maintained to run continuously for at least 24 hours of measurement time TM by: providing the meter or meter head with an energy source that enables it to run continuously for at least the measurement time TM; or equipping the test station with a winding and / or rocking device to wind or rock the meter or meter head to make it run again for at least the measurement time TM.

2. The method according to claim 1, characterized in that, At an initial time t0, at least one initial optical image of the pointer of the watch or the watch head is acquired by referring to a fixed point on the watch or the watch head and / or referring to a fixed point on the tool that encapsulates and locks the watch or the watch head. At least after the measurement time TM, at the final time measured on the reference clock, with reference to a fixed point on the meter or meter head and / or with reference to a fixed point contained in the tool, at least one final optical image of the pointer of the meter or meter head is acquired; the position of the pointer at the initial time and the final time is determined by a vision recognition device equipped at the test station; Calculate the difference between the reference position on the reference clock and the actual position of the pointer, and display the measured state deviation value.

3. The method according to claim 2, characterized in that, Between the initial optical image acquisition and the final optical image acquisition, continuous or quasi-continuous acoustic measurements are performed on the oscillator or speed controller in the meter or meter head to determine the time deviation.

4. The method according to claim 3, characterized in that, After the measurement time TM ends, the timekeeping of the meter is acoustically evaluated by counting the number of ticks corresponding to the elapsed time.

5. The method according to any one of claims 1 to 4, characterized in that, Between the initial time and the final time, dynamic movement within a dynamic space is applied to the watch or watch head to wind the watch or watch head and / or perform a timekeeping test at a standard timing position.

6. The method according to any one of claims 1 to 5, characterized in that, Between the initial moment and the final moment, the watch or meter head is left at rest in the standard timing position, and / or any other stress is applied to the speed regulator and display mechanism of the watch or meter head.

7. The method according to claim 5 or 6, characterized in that, Spatial movement is applied to the watch or watch head to perform a timekeeping test at a standard timing position and determine the timekeeping deviation value at the standard timing position; the timekeeping deviation value and the state deviation value are compared with internal specifications to permit or prohibit subsequent manufacturing of the watch or watch head.

8. The method according to any one of claims 5 to 7, characterized in that, The timekeeping test was conducted using acoustic measurements at the standard timing position.

9. The method according to any one of claims 1 to 8, characterized in that, Between the initial moment and the final moment, under predetermined time, temperature, and humidity conditions, the watch or watch head is placed in an oven.

10. The method according to any one of claims 1 to 9, characterized in that, The table or header is encapsulated and locked in a transparent processing box; except for the initial time, all processing operations performed on the table or header between the initial time and the final time are performed within the processing box.

11. The method according to claim 10, characterized in that, The at least one initial optical image is acquired before the watch or watch head is placed into the processing box, and the at least one final optical image is acquired after the watch or watch head is removed from the processing box.

12. The method according to any one of claims 1 to 10, characterized in that, The method is applied to mechanical watches.

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