Watch with mechanical or electronic movement equipped with a striking mechanism

Abstract

A watch according to the invention comprises a striking mechanism, including at least one fixed gong (4) and at least one hammer (15), as well as a battery (6) and an integrated circuit (7) powered by the battery and configured to produce current pulses, and an electrodynamic actuator (17) connected to the integrated circuit and capable of receiving said pulses, the actuator being integral with the hammer or connected to the hammer so as to generate, in response to said pulses, a movement of the hammer from its rest position, said movement being capable of striking the gong with the hammer. The mechanism also includes a spring (27) connected to the hammer so as to return the hammer to its rest position after the impact. In particular embodiments, the hammer undergoes one or more pre-oscillations before striking. In one particular embodiment, the hammer and the gong are provided with attracting magnets.

Description

Technical field

[0001] The invention relates to a striking mechanism for a watch. Said mechanism is capable of generating one or more sounds to signal an alarm or minute repeaters. Technological background

[0002] In mechanical watches equipped with a minute repeater system, said system traditionally comprises one or more gongs, each consisting of a metal wire generally of circular shape and placed in a plane parallel to the dial of the watch. The metal wire of each gong is generally arranged around the watch movement, in the watch cage and above a plate on which the different parts of the movement are mounted. One end or more ends of each gong are fixed, for example by soldering, to a gong holder secured to the plate, for example, which may be unique for all the gongs. The other end of each gong may generally be free.

[0003] The striking mechanism includes at least one hammer operated at the user's request, to indicate the time by a series of hammer impact noises on the gong. Each hammer is equipped with a return spring allowing it to fall back on the gongs. The energy reserve for a series of strikes comes from a barrel spring, which is regularly recharged by the user. This type of mechanism is quite complex and bulky and the energy of the impacts is limited and often decreases with the mechanical discharge of the spring, the interval between impacts is also dependent on the discharge of the spring. The autonomy of the barrel spring is ultimately limited, and it often has to be rearmed once the alarm or audible indication has ended.

[0004] Electronic watches of the quartz type or others are also known, equipped with a striking system and / or minute repeaters, in which a piezoelectric actuator acts as a loudspeaker. The striking takes place using an integrated circuit linked to the actuator. The loudspeaker produces a series of sounds for an alarm, or to indicate the time at the user's request. It is clear that this system is less complex and that the autonomy of this type of striking, as well as the volumes are greater than in the case of a mechanical watch. However, the sound produced by this mechanism is synthetic and unattractive compared to the natural sound of a mechanical gong. Moreover, in the limited spatial volume of a watch, it is difficult to implement a loudspeaker that is capable of reproducing a sound that approaches the sound of the mechanical gong.

[0005] Patent application FR 1 335 311 A describes a striking mechanism for a timepiece. This mechanism is composed of a gong arranged at least partly around the movement and an electromechanical device comprising at least one hammer for striking the gong by activating a coil mounted on a metal axial rod. The hammer is activated by an electrical control.

[0006] Patent application CH 705 303 A1 describes a timepiece that includes a sound mechanism, which includes a striking mechanism in a sealed portion of the case and at least one gong to be activated by the striking mechanism. The hammer is electrically activated to strike the gong.

[0007] Patent application FR 2 061 680 A1 describes an electric hour-striking mechanism for a clock. The mechanism comprises an electromagnet, which is powered by pulses and which acts on a clock hammer to strike a bell or gong. Summary of the invention

[0008] The invention therefore aims to overcome the drawbacks of the state of the art by providing a striking mechanism for a watch, which uses a new principle for generating one or more sounds from at least one gong.

[0009] To this end, the invention relates to a watch provided with a striking mechanism and to a method for producing sounds by the mechanism, comprising the features defined in the claims.

[0010] A watch according to the invention comprises a striking mechanism, according to claim 1.

[0011] A watch according to the invention may comprise a basic mechanical or electronic watch movement. In both cases, the watch becomes a hybrid watch that overcomes the drawbacks described above. In the first case, the watch comprises a majority of mechanical components supplemented by an electromechanical striking mechanism, which is more compact and capable of increasing autonomy, as well as energy and uniformity of impacts compared to the state of the art. In the second case, the watch comprises a majority of electronic and / or electromechanical components, as well as a gong that generates a natural sound instead of the synthetic sounds produced by electronic watches of the state of the art.

[0012] According to claims 9 and 10, the hammer undergoes one or more pre-oscillations before reaching impact. According to claim 8, the hammer and the gong are respectively provided with attracting magnets. Brief description of the figures

[0013] The invention will be described below in more detail with the aid of the attached drawings, given as non-limiting examples, in which: there Figure 1 represents a minute repeater mechanism integrated into a mechanical movement watch according to the invention, the Figure 2 represents a minute repeater mechanism integrated into an electronic movement watch according to the invention, the Figure 3 represents a schematic diagram of a hammer provided with its electrodynamic actuator as it is applicable in a watch according to the invention, the Figure 4a represents a diagram of the hammer impulses and movements when applying a single current pulse. Figures 4b and 4c represent patterns, impulses and movements of the hammer in the case of one or two pre-oscillations of the hammer, and the Figure 5represents a prototype of a striking mechanism applicable in a watch according to the present invention. Detailed description of the invention

[0014] To the Figure 1, we see the main components of a minute repeater mechanism integrated into a mechanical movement watch according to the invention. The hour and minute hands 1 and 2 are linked to a traditional mechanical movement 3 shown without details. The minute repeater system comprises a gong 4 fixed to the plate (not shown) of the watch by a gong holder 5. The gong 4 can be produced according to an embodiment known from the state of the art. The minute repeater mechanism further comprises an electrical energy accumulator 6, such as a battery, and an integrated circuit 7 powered by the electrical energy accumulator 6, as well as detectors 8 and 9 of the position of the axes of the hands 1 and 2. These detectors are also known per se. They can be configured to detect for example, but not limited to, the position of a series of teeth provided on the respective axes.

[0015] A hammer 15 is rotatably mounted about a rotation axis 16, so that the hammer can impact the gong 4. The rotation of the hammer 15 is actuable by an electrodynamic actuator 17, which is connected to the integrated circuit 7. The hammer 15 is provided with a spring (not shown) which returns the hammer to its rest position after the impact. The actuator 17 receives current pulses generated by the integrated circuit 7, based on the position detected by the detectors 8 and 9, so as to announce the time upon request of the user, by a series of specific sounds. Preferably, a second gong 4' and a second hammer provided with its electromechanical actuator (not shown) are present to generate distinct sounds.The dimensions of the actuator 17 and the hammer 15 are shown only as an indication, but it is clear that all of these components will occupy only a fraction of the space occupied by a purely mechanical striking mechanism, which generally occupies the complete surface of the dial.

[0016] There Figure 2 represents an electronic watch of the quartz type according to the invention, also comprising two mechanical gongs 4 and 4' and corresponding hammers 15 and electrodynamic actuators 17 (only one hammer and one actuator is shown), of the same type and dimensions as in the case of the Figure 1. Hands 1 and 2 are rotated by a motor 20 powered by an electrical energy accumulator 6, such as a battery, using an integrated circuit 7 linked to a quartz 21, said components being part of the electronic movement of the watch, as known in the prior art. Electrodynamic actuator 17 receives pulses from integrated circuit 7 of the electronic movement. The presence of detectors 8 and 9 of the position of the axes of hands 1 and 2 is optional in this embodiment. Instead of having detectors 8 and 9, it is also possible to configure integrated circuit 7 so that it can determine the time to be announced by the hammers.

[0017] Advantageously, a watch according to the invention combines one or more mechanical gongs with a hammer actuated by an electrodynamic actuator. Compared to purely mechanical watches, this solution allows for a much greater autonomy, a higher sound intensity, improved repeatability of the impulses, a constant interval between the impulses, as well as a spatial occupation of the striking system which is much lower than that of mechanical striking systems. In an electronic watch, the invention makes it possible to implement a natural sound of alarms and / or minute repeaters.

[0018] The loudness of the impact noises depends on the performance of the electrodynamic actuator used. Tests using an existing electrodynamic vibrator were carried out. As can be seen below, the finding is that the energy of a single impact is comparable, but still lower than the energy of the impact of a mechanical actuator. However, particular embodiments of the invention are linked to the way in which the current pulses sent to the actuator 17 are configured with respect to the rest position of the hammer 15, and with respect to a number of parameters of the striking mechanism. A block diagram of the mechanism is shown in Figure 3. The hammer 15 is integral with a magnet 25 linked to the plate 26 of the watch by a return means 27, which may be a spring. A coil 28 surrounds the magnet 25 and receives the current pulses I(t) generated by a voltage signal U(t), which actuate axial movements of the hammer 15, in the direction x. The assembly of the magnet 25, the coil 28 and the spring 27 constitutes the electrodynamic actuator 17. The distance between the gong 4 and the hammer 15 in the rest position is the distance x 0 indicated in the drawing. In this position, the spring 27 is not prestressed. Depending on the direction of the current I, the movement of the hammer 15 takes place in the direction +x or -x. When the current is interrupted, the spring 27 returns the hammer to the rest position after a number of oscillations determined by the characteristics of the mass-spring system. The system represented in the Figure 3 is equivalent to the system represented in Figures 1 and 2, insofar as in the latter the spring could be a torsion spring or a leaf spring and the actuator is configured to actuate a rotation of the hammer about the axis 16.

[0019] It should be noted that the return means 27 can also be a mechanical cam, or even an electromagnetic force, or another means.

[0020] There Figure 4a represents the evolution as a function of the movement of the hammer 15 for the case of a single current pulse 31 which activates a movement of the hammer towards the gong 4 until the impact at time ti. The following hypotheses make it possible to study the movement of the hammer and to calculate the energy of the impact: The voltage induced by the movement is negligible compared to the applied voltage. Voltage, current and electromechanical force F em are considered constant over the duration of the pulse (also referred to as peak values).

[0021] Impulse 31 is actually represented in the figure as an impulse of force F em . Friction is neglected, the schedule x(t) is sinusoidal with a period corresponding to the natural frequency f 0 of oscillation of the mass-spring system, f 0 being given by the formula f 0 = 1 2 π k m with k the spring constant (N / m) and m the mass of the hammer + magnet (kg).

[0022] The magnitude of the electromechanical force F em applied by the impulse is such that the force actuates an oscillation 30 of amplitude 2x 0 . This oscillation is illustrated by curve 30 up to the moment of impact ti. If the stamp were not present, the oscillation would follow the dotted curve. The time between t=0 and the maximum of the dotted curve corresponds to 1 2 τ with τ= 1 / f 0 . We see that in the form shown, the duration of the pulse 31 is such that the impact takes place approximately at the moment when the speed of the hammer is maximum. This implies that the duration of the pulse is approximately τ 4 .

[0023] The law of conservation of energy allows us to relate the work of the force F em , on the path x 0 to the kinetic energy E cin received by the actuator. The electrical balance is also evaluated. It can be shown that the kinetic energy of the impact and the electrical energy consumed are respectively E cin _ 1 = F em x 0 − 1 2 kx 0 2 E el _ 1 = 0.5 ⋅ πR m k F em k u 2 with R the electrical resistance (Ohm), and ku the coil-magnet coupling factor (N / A).

[0024] As shown in the Figure 5, the tested test prototype used for the actuator - hammer - spring assembly, a vibrator 50 striking a mechanical gong mounted on a brass base 51. The x direction is indicated on the drawing. The dimensions are indicated in mm for example the diameter of the gong can be 35.6 mm, the base 51 can be 44 mm by 44 mm, and the vibrator can be 24.15 mm long and 9.56 mm wide. The values ​​of the parameters that appear in formulas (1) and (2) were established as follows: k = 1606 N / m, x 0 = 0.19 mm, R = 80 Ohm, m = 2.68 gr, ku = 2.07 [N / A], U = 9 V => I = U / R = 112.5 mA, => F em = ku *I = 0.233 N.

[0025] With these parameters, the kinetic energy of the impact made by the prototype according to the form of execution of the Figure 4awas calculated as 15.3 µJ. This is of the same order of magnitude as the impact achieved by a mechanical ringing system, estimated at 50 µJ, but clearly lower than the latter. To increase this energy, one can apply more powerful current pulses and / or optimize the actuator by modifying its parameters such as mass, spring constant and coupling factor. But as can be seen below, simply adding pre-oscillation pulses increases this energy a lot, even in case of a non-optimized actuator.

[0026] According to another embodiment, the impact energy generated by an electromechanical force equal to or less than the force F em applied for the previous case which uses a single impulse, is increased by operating the hammer in a different manner, illustrated for example in Figure 4b. According to this form, a first inverse pulse 35 of the same magnitude F em as the single pulse of the previous form is first applied. The inverse pulse 35 therefore activates a negative pre-oscillation 30, having an amplitude of 2x 0 in the -x direction. At the moment when the hammer reaches the extreme point at the position -2x 0 (at which the distance between the hammer and the gong equals 3 times x 0 ), the first pulse is followed by a second positive pulse 36 of the same magnitude F em , which generates an oscillation 38 that will launch the hammer 15 in the direction of the gong 4 until the impact at the moment ti , which arrives at t = 3 τ 4 .

[0027] Reasoning in a similar way as before, we obtain this time for the energies: E cin _ 2 = 5 ⋅ F em x 0 − 1 2 kx 0 2 E el _ 2 = 1.5 ⋅ πR m k F em k u 2

[0028] There Figure 4crepresents the impulses and displacements during a double pre-oscillation. A first positive impulse 40 of amplitude F em / 2 is applied so that the hammer approaches the gong without touching it by a first pre-oscillation 43, followed by t = τ 2 by a second negative pulse 41 of magnitude F em , so that a second pre-oscillation 44 brings the hammer back to a distance of -3x 0 from the rest position. At the extreme point at -3x 0 (at which the distance between the hammer and the gong equals 4 times x 0 ), at t = τ , a third positive pulse 42 of amplitude F em generates the final oscillation 45 which launches the hammer towards the gong until the moment of impact ti arriving at t = 5 τ 4 .

[0029] The energies are given in this case by the following expressions: E cin _ 3 = 8.5 ⋅ F em x 0 − 1 2 kx 0 2 E el _ 3 = 1.75 ⋅ πR m k F em k u 2

[0030] The following table groups together the theoretical performances evaluated in the 2 previous sections: Excitation mode Kinetic energy Electrical energy consumed Multiplicative ratio of E el to reach Ecin_3 1 pulse F em x 0 − 1 2 kx 0 2 0.5 ⋅ πR m k F em k u 2 20.6 x 2 pulses 5 ⋅ F em x 0 − 1 2 kx 0 2 1.5 ⋅ πR m k F em k u 2 2.5 x 3 pulses 8.5 ⋅ F em x 0 − 1 2 kx 0 2 1.75 ⋅ πR m k F em k u 2 1 x (reference)

[0031] The right column expresses the multiplicative factor to be applied to the electrical consumption of the mode in question, to arrive at the same kinetic energy as with 3 pulses ( Figure 4c ). Example :

[0032] E cin (1 imp) requires an EM force 8.5x greater to reach E cin (3 imp). However, the consumption will be 8.5^2 = 72x greater. But since the consumption ratio is 1.75 / 0.5 = 3.5, we finally obtain 8.5^2 / 3.5 = 20.6x.

[0033] We can clearly see the significant energy gain by applying 1 or 2 pre-oscillations, instead of a single direct pulse. For example, consumption would increase by a factor of 20.6 / 2.5 = 8 x in the case where we seek to obtain the same kinetic energy with a single pulse, as with 2 pulses.

[0034] The following table is a numerical application of the 6 formulas above, with the data from the prototype of the Figure 5 . Excitation mode Kinetic energy Electrical energy consumed E cin / E el yield 1 pulse 15.3 µJ 2.06 mJ 0.7 % 2 pulses 192 µJ 6.17 mJ 3.1 % 3 pulses 347 µJ 7.19 mJ 4.8 %

[0035] It is clear that the 50 µJ energy of the mechanical ring is largely exceeded with 2 or 3 pulses.

[0036] Since in reality the above-mentioned simplifications are only approximate (e.g. friction and induced voltage are not zero, frequency is not exactly f 0 ), embodiments that include at least one pre-oscillation can be formulated as follows: the hammer is actuated so that it undergoes at least two oscillations before reaching impact, at least one of which is designated 'pre-oscillation', the pre-oscillation(s) being followed by a final oscillation that leads to impact. In this context, the term 'oscillation' refers to the movement between two consecutive extreme positions of a vibration experienced by the hammer. The oscillations are generated by a series of pulses of opposite signs, so that from the second pulse onwards, each pulse is applied approximately at the time when the hammer reaches an extreme point of the oscillation generated by the previous pulse.Generally, the magnitudes of the pulses that generate pre-oscillations are equal to or less than the magnitude of the pulse that generates the final oscillation.

[0037] The number of pre-oscillations can be greater than two, provided that the magnitude of the pulses is adapted so as to avoid impacts during the pre-oscillations.

[0038] By extension to multiple pre-oscillations, we can clearly see that the applied alternating signal, square-shaped or otherwise, must have a frequency close to the natural oscillation frequency of the mass-spring system, so as to effectively amplify the oscillations. This resonance phenomenon is well known to those skilled in the art.

[0039] According to yet another embodiment, the hammer 15 and the gong 4 are provided with attracting magnets, one magnet being fixedly mounted on the gong 4 and the other magnet being fixedly mounted on the hammer 15, so that the magnets come into physical contact at the moment of impact of the hammer on the gong. The attractive force is such that the hammer and the gong remain in contact during the vibration of the gong, until the moment when a reverse impulse applied to the electrodynamic actuator causes the hammer to recoil, breaking the contact between the magnets. This prolonged contact between the hammer and the gong is capable of improving the transfer of kinetic energy from the hammer to the gong. This embodiment can be combined with the methods described above according to which the striking is operated without or with pre-oscillations.In the case of multiple pre-oscillations, their amplitudes must be adjusted to prevent the magnets from sticking the hammer to the gong before the desired impact moment.

Claims

1. A watch provided with a striking work, the striking work comprising at least one gong attached (4) to a gong holder (5), and at least one hammer (15) for activating the gong to vibrate it, characterised in that the striking work further comprises: - an electric energy accumulator (6), - an integrated circuit (7) powered by the electric energy accumulator (6) and configured to produce at least one current impulse, - an electrodynamic actuator (17) which is connected to the integrated circuit and which is capable of receiving said impulse(s), the actuator comprising a magnet (25) integral with a hammer (15) or connected to the hammer so as to generate, in response to a single current impulse (31), an oscillation (30) of the hammer (15) from the rest position, and wherein the strike occurs approximately when the hammer speed during said oscillation is maximal, the actuator also comprising a coil (28) surrounding the magnet (25) and which receives said impulse(s), the oscillation being capable of actuating a hammer strike on the gong (4), - a return means (27) connected on one hand to the watch plate (26) and on the other hand to the magnet (25) and connected to the hammer so as to return the hammer (15) to its rest position after the strike.

2. The watch according to claim 1, characterised in that the watch is a mechanical movement watch (3).

3. The watch according to claim 1, characterised in that the watch is an electronic movement watch, and wherein the electric energy accumulator (6) and the integrated circuit (7) form part of the watch movement.

4. The watch according to claim 1, characterised in that the integrated circuit (7) is configured to produce a series of impulses of opposite signs so that: - the hammer (15) undergoes at least two oscillations before reaching the strike, at least one of which is called 'pre-oscillation', the pre-oscillation(s) being followed by a final oscillation which leads to the strike, - from the second impulse, each impulse is applied approximately when the hammer reaches the extreme point of the oscillation generated by the previous impulse, - the magnitude of the impulses that generate the pre-oscillations is equal to or less than the magnitude of the impulse that generates the final oscillation.

5. The watch according to claim 4, characterised in that the hammer (15) undergoes a single pre-oscillation (37), followed by the final oscillation (38).

6. The watch according to claim 4, characterised in that the hammer (15) undergoes two pre-oscillations (43, 44), followed by the final oscillation (45).

7. The watch according to any one of claims 1, 5 and 6, characterised in that the frequency of the impulse(s) is approximately equal to the resonant frequency of the mass-spring system which corresponds to the assembly of the hammer (15) and the return means, such as a spring (27).

8. The watch according to any one of the preceding claims, further comprising a pair of attracting magnets, one magnet being permanently mounted on the gong (4) and the other magnet being permanently mounted on the hammer (15), so that the magnets are physically contacted when the hammer strikes the gong.

9. A method for generating a striking sound in a watch according to claim 1, characterised in that the integrated circuit (7) produces a single current impulse (31) which generates an oscillation (30) of the hammer (15) from the rest position, and wherein the strike occurs approximately when the hammer speed during said oscillation is maximal.

10. The method for generating a striking sound in a watch according to claim 1, characterised in that the integrated circuit (7) produces a series of impulses of opposite signs to each other, so that: - the hammer (15) undergoes at least two oscillations before reaching the strike, at least one of which is called 'pre-oscillation', the pre-oscillation(s) being followed by a final oscillation which leads to the strike, - from the second impulse, each impulse is applied approximately when the hammer reaches the extreme point of the oscillation generated by the previous impulse, - the magnitude of the impulses that generate the pre-oscillations is equal to or less than the magnitude of the impulse that generates the final oscillation.

11. The method according to claim 10, characterised in that the hammer (15) undergoes a single pre-oscillation (37), followed by the final oscillation (38).

12. The method according to claim 11, characterised in that at the end of the pre-oscillation (37), the hammer is moved away from the gong by approximately three times the distance (x0) corresponding to the rest position.

13. The method according to claim 11, characterised in that the hammer (15) undergoes two pre-oscillations (43, 44), followed by the final oscillation (45).

14. The method according to claim 13, characterised in that the first pre-oscillation (43) brings the hammer close to the gong without touching it, and that at the end of the second pre-oscillation (44), the hammer is moved away from the gong by approximately four times the distance (x0) corresponding to the rest position.

15. The method according to any one of claims 9 to 14, characterised in that the frequency of the impulse(s) is approximately equal to the resonant frequency of the mass-spring system which corresponds to the assembly of the hammer (15) and the return means, such as a spring (27).

Images