Shock-resistant piezoelectric rotary motor, particularly for portable clocks

Abstract

To provide a rotary piezoelectric motor capable of withstanding a high electromagnetic field and a lateral shock while maintaining low power consumption and volume.SOLUTION: A rotary piezoelectric motor comprises a rotor 3 configured to rotate and actuate a mechanical device, and a stator 2 configured to rotate the rotor with a piezoelectric actuator. The piezoelectric actuator comprises a movable element 5 that rotates the rotor in a first direction with its motion. There are two electrically actuatable resonators 6, 7. The resonators are connected to the movable element and move relative to the rotor to rotate the movable element. The two resonators are positioned relative to the movable element so as to vibrate the movable element in first and second directions that are different from each other. Each resonator has a rotation center. The two resonators are positioned relative to the movable element such that torque due to all acceleration forces applied to a plane of each resonator about each rotation center is zero.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to the technical field of rotary piezoelectric motors. The present invention further relates to the technical field of timepieces comprising such rotary piezoelectric motors as described above.

Background Art

[0002] The electric motors commonly used in the manufacture of portable timepieces (e.g., wristwatches, pocket watches) are "Lavet" type rotary motors that operate on electromagnetic physical principles. This type of motor generally comprises a stator with a coil and a magnetized rotor that rotates by shifting the phase of the coil.

[0003] However, in such motors, the resistance to high magnetic fields is limited. When the magnetic field is greater than a specific magnetic field value, the movement of the motor becomes abnormal. Generally, when the magnetic field is greater than 2 mT, the movement of the motor becomes abnormal.

[0004] Therefore, to avoid this problem, it is necessary to design a motor that operates on other physical principles.

[0005] For example, there is an electrostatic motor with comb teeth as described in Swiss Patent CH709512. However, the comb teeth occupy space and consume more energy than a "Lavet" type motor.

[0006] Motors based on the piezoelectric effect have also been developed, for example, in European Patent EP0587031. However, this motor is limited to actuating the calendar. Also, due to high power consumption and the risk of early wear, it cannot drive the second hand, which usually requires the most energy.

[0007] To reduce power consumption, an orbital piezoelectric motor is described in European patent application EP21216102.0 filed for The Swatch Group Research and Development Ltd. In this motor, the rotor is driven by a ring-shaped movable element that traces an orbit so as to contact the rotor disposed inside the ring. To move the movable element, the piezoelectric actuator includes a plurality of piezoelectric resonators formed by flexible vibrating arms, these arms hold and move the movable element, and the arms contain a piezoelectric material that can be actuated.

[0008] However, in this method, although high miniaturization can be achieved, a lateral impact directly applies a force to the ring, interfering with the orbital motion, and in some cases, it chronometrically deteriorates the movement of a timepiece equipped with such a piezoelectric motor.

Summary of the Invention

Problems to be Solved by the Invention

[0009] An object of the present invention is to provide a rotary piezoelectric motor that can withstand a high electromagnetic field and lateral impacts while maintaining low power consumption and a small volume, especially for timepieces.

Means for Solving the Problems

[0010] For this purpose, the present invention relates to a rotary piezoelectric motor, especially for a timepiece, and includes a rotor configured to rotate and actuate a mechanical device, and a stator provided with a piezoelectric actuator and configured to rotate the rotor. The piezoelectric actuator includes a movable element that rotates the rotor in a first direction by movement.

[0011] The piezoelectric actuator has two piezoelectric resonators that can be electrically actuated. These two resonators are connected to the movable element to move the movable element relative to the rotor and rotate the movable element. The two resonators are arranged with respect to the movable element so as to vibrate the movable element in a first direction and a second direction different from each other. Each resonator has a center of rotation. The two resonators are arranged with respect to the movable element such that the torque caused by all the accelerating forces applied in the plane of each resonator around each center of rotation is zero. In this respect, the present invention is revolutionary.

[0012] A stator having such a configuration can easily transmit a rotational motion to the rotor using a piezoelectric actuator. The movable element can be moved so as to contact the rotor, and the motion can be transmitted in one direction. Therefore, when the resonator vibrates, the movable element performs an orbital rotational motion, contacts the rotor, and transmits a force to the rotor to rotate it in the first direction.

[0013] Since the torque caused by all the forces applied to each center of rotation is zero in the plane of each resonator, the influence of lateral impacts can be greatly reduced and, in some cases, canceled out. This eliminates the risk of disturbing the orbital motion and, therefore, eliminates chronometer-like damage in the case of a clockwork motor.

[0014] Also, by providing two piezoelectric resonators to generate vibrations in substantially different directions, the movable element can be moved so as to perform an orbital motion without the need to increase the number of resonators several times.

[0015] In a specific embodiment of the present invention, the first resonator and the second resonator are arranged perpendicular to each other such that the first direction and the second direction are substantially perpendicular. In this way, a circular orbital motion can be obtained.

[0016] In a particular embodiment of the present invention, the first resonator and the second resonator are respectively arranged on different sides of the movable element, preferably these sides are adjacent to each other.

[0017] In a particular embodiment of the present invention, it comprises a first translation stage that enables the movable element to move in the first direction.

[0018] In a particular embodiment of the present invention, it comprises a second translation stage that enables the movable element to move in the second direction.

[0019] In a particular embodiment of the present invention, the second translation stage is arranged in series with the first translation stage, and the movable element is connected to the second translation stage.

[0020] In a particular embodiment of the present invention, the first translation stage and the second translation stage are substantially perpendicular to each other.

[0021] In a particular embodiment of the present invention, a translation stage is arranged on the opposite side of the resonator with the movable element in between.

[0022] In a particular embodiment of the present invention, each resonator has a vibrating weight actuated by a pair of flexible blades containing a piezoelectric material.

[0023] In a particular embodiment of the present invention, the movable element performs an orbital motion in a second direction opposite to the first direction.

[0024] In a particular embodiment of the present invention, the movable element is always in contact with the rotor while the rotary motor is operating.

[0025] In a particular embodiment of the present invention, the movement of the movable element causes the rotor to rotate continuously.

[0026] In a particular embodiment of the present invention, the movable element is in the form of a ring, and the rotor is disposed inside the ring.

[0027] In a particular embodiment of the present invention, the movable element and the movable rotor are in contact inside the ring.

[0028] In a particular embodiment of the present invention, the rotor has a gear, and the ring has an inner tooth row that engages with the outer tooth row of the gear.

[0029] In a particular embodiment of the present invention, the movable element is fixed so as to rotate on itself.

[0030] In a particular embodiment of the present invention, the movable element is disposed around the rotor.

[0031] In a particular embodiment of the present invention, the first resonator and the second resonator are actuated so that their phases are shifted by 90°.

[0032] In a particular embodiment of the present invention, the first resonator and the second resonator are respectively disposed on different sides of the movable element, and these two sides are preferably adjacent to each other.

[0033] The present invention further relates to a timepiece movement comprising a gear transmission configured to rotate at least one needle, and the piezoelectric motor as described above configured to actuate this gear transmission.

[0034] Other features and advantages will become apparent by reading the following description, which is for illustrative purposes and not intended to be limiting, with reference to the accompanying drawings.

Brief Description of the Drawings

[0035]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0036] Figs. 1 to 5 show an embodiment of a rotary piezoelectric motor 1. The piezoelectric motor 1 can be used, in particular, in a timepiece to actuate a display device such as a hand disposed on a dial. The piezoelectric motor 1 preferably extends substantially within one plane.

[0037] The piezoelectric motor 1 includes a rotor 3 that can rotate on itself, and this rotor 3 is configured to rotate and actuate a mechanical gear transmission, particularly for a display device. The piezoelectric motor 1 includes a stator 2 configured to actuate and rotate the rotor 3.

[0038] This rotor 3 is, for example, a gear 9 arranged at the center of the piezoelectric motor 1. This gear 9 is attached, for example, to a shaft with pivots at both ends, and these pivots are attached to bearings that allow the shaft to rotate. The gear 9 has an outer ring 28 and a hub 27 at the center, and this hub 27 is connected to the ring 28 by sturdy spokes 19. On the shaft 13, there is a pinion 21 parallel to the gear 9, and this pinion 21 is configured to transmit the motion received by the gear 9 to a gear transmission, for example, to the movement of a timepiece. On the rotor 3, there are peripheral teeth 10 on the ring 28, which enables the gear 9 to be actuated.

[0039] Preferably, the rotor 3 and / or the stator 2 preferably entirely contain a microfabricable material such as silicon. Instead, the rotor 3 can be made of metal to reduce wear and friction when the stator 2 is made of silicon, and vice versa.

[0040] Furthermore, by microfabrication, the rotor 3 and / or the stator 2 preferably entirely contain materials such as quartz, nickel (obtained by electroforming of metal or LIGA - type methods), diamond (obtained by ALD - type deposition), glass (obtained by selective laser etching (SLE)).

[0041] The stator 2 comprises a static fixed element 4 and a movable element 5 configured to actuate the gear 8 of the rotor 3. The movable element 5 is arranged away from the fixed element 4. The movable element 5 is in the shape of a ring with a square outer frame and a circular inner frame.

[0042] The movable element 5 is arranged around the rotor 3, and the rotor 3 is arranged inside the ring. The movable element 5 has an inner tooth row 12 in the shape of a circle of the ring, and this inner tooth row 12 engages with the peripheral teeth 10 of the rotor 3 to rotate the rotor 3. The ring is wider than the rotor 3 to enable the insertion of the rotor 3 and the movement of the movable element 5.

[0043] Due to the movement of the movable element 5 and the contact between the movable element 5 and the rotor 3, the rotor 3 rotates in the first direction.

[0044] For this purpose, the stator 2 comprises a piezoelectric actuator.

[0045] The piezoelectric actuator has two electrically actuatable resonators 6, 7. The first resonator 6 and the second resonator 7 are connected to the movable element 5 and move relative to the rotor 3 to enable the rotation of the movable element 5.

[0046] The resonators 6, 7 generate a vibrating motion to guide the movable element 5 to perform an orbital motion. Thanks to the first resonator 6, the movable element 5 can move in the first horizontal direction X, and thanks to the second resonator 6, the movable element 5 can move in the second vertical direction.

[0047] The first resonator 6 and the second resonator 7 each comprise a vibration weight 20. Each vibration weight 20 has an elongated shape extending along one side 9 of the shape of the movable element 5. Each vibration weight 20 has at least one inertial block at one end.

[0048] When the resonators 6, 7 are activated, the vibration weights 20 rotate about the center of rotation while vibrating.

[0049] The characteristics and operations of the resonators 6, 7 will be described in detail below this description. Vibrations occur in a direction transverse to the said side of the frame.

[0050] Each vibration hammer 20 is connected to the movable element 5 by substantially straight second flexible blades 11, 12. The second flexible blades 11, 12 are attached to an inertia block 21 disposed at the end of the vibration hammer 20 from studs 22 extending from two adjacent sides of the shape of the movable element 5. The second flexible blades 11, 12 are substantially perpendicular to the arms of the vibration hammer 20.

[0051] The second flexible blades 11, 12 are arranged to be perpendicular to each other along two adjacent sides of the shape of the movable element 5.

[0052] When the vibration hammer 20 vibrates out of phase, each second flexible blade 11, 12 alternately pulls and pushes the movable element 5.

[0053] Thereby, the movable element 5 performs an orbital motion. The orbital motion means a rotational motion of the movable element 5 about a rotational axis offset from the center. Also, since the degree of freedom of the movable element 5 is blocked by the flexible translation stage described below, it does not rotate on itself.

[0054] In the present invention, only two resonators 6, 7 are used to generate this orbital motion. It is not necessary to provide additional resonators to generate this motion.

[0055] To actuate the movable element 5, the first and second resonators 6, 7 vibrate in substantially orthogonal directions.

[0056] The two resonators are preferably arranged perpendicular to each other and are arranged on two adjacent sides of the shape of the movable element 5. In this way, a substantially circular orbital motion can be obtained.

[0057] In order to follow and guide the movement of the movable element 5 along the third side, the movable element 5 is further connected to the stator 4 by two flexible translation stages 24, 25. The first translation stage 24 and the second translation stage 25 are configured in series, and the movable element 5 is attached to the second translation stage 25.

[0058] Each of the translation stages 24, 25 has two substantially parallel third flexible blades 31, 32, 33, 34 and movable rigid parts 35, 36 to which these third flexible blades 31, 32, 33, 34 are connected.

[0059] The third flexible blades 31, 32 of the first translation stage 24 are connected to the stator 2 at one end and to the first rigid part 30 at the other end.

[0060] The third flexible blades 33, 34 of the second translation stage 25 are connected to the first rigid part 35 at one end and to the second rigid part 36 at the other end. This second rigid part 36 is connected to the frame of the movable element 5.

[0061] Thanks to the first translation stage 24, the movable element 5 can move with a first degree of freedom in the horizontal direction along the axis X, and thanks to the second translation stage 25, the movable element 5 can move with a second degree of freedom in the vertical direction along the axis Y. Preferably, the direction of the second degree of freedom is substantially orthogonal to the direction of the first degree of freedom.

[0062] For this reason, the first translation stage 24 and the second translation stage 25 are substantially orthogonal to each other. The two third flexible blades 31, 32, 33, 34 prevent the movable element 5 from rotating on itself but allow lateral movement. Thanks to this feature, the movable element 5 can transmit torque to the rotor 3 as will be explained below.

[0063] Each of the translation stages 24, 25 is arranged on the opposite side of the resonators 6, 7 with the movable element 5 in between. That is, the pairs formed by the resonators 6, 7 and the translation stages 24, 25 are arranged on both sides of the movable element 5 in the same direction, whereby it is ensured that the motor 1 is very small.

[0064] The resonators 6, 7 are configured to move the movable element 5 relative to the rotor 3 to rotate the rotor 3. For this purpose, the resonators 6, 7 are actuated out of phase with each other.

[0065] The phase shift between the resonators 6, 7 generates an orbital movement of the movable element 5, which is preferably circular. The movable element 5 performs a circular motion while remaining fixed in rotation on itself thanks to the two return stages 24, 25.

[0066] The movement of the movable element 5 is preferably continuous and rotates the rotor 3 continuously. For this purpose, the movable element 5 is always in contact with the rotor 3 while the motor is operating. The contact point P between the movable element 5 and the rotor 3 can move inside the ring.

[0067] Figures 2 to 5 show various consecutive instants while the contact point P between the rotor 3 and the movable element 5 moves inside the ring, in this case counterclockwise. The orbital movement of the ring with a larger inner space than the rotor 3 causes the contact point P between the ring and the rotor 3 to move. Different parts of the inner tooth row 12 of the ring mesh with the circumferential teeth 10 of the gear 9 at each instant. Accordingly, the rotor 3 rotates on itself in the direction opposite to P, that is, counterclockwise.

[0068] In FIG. 2, the movable element 5 is raised, and the contact point P is at the lower part of the gear 9, that is, in the 6 o'clock direction. In FIG. 3, the movable element 5 is shifted to the right, and the contact point P is to the left of the gear 9, that is, in the 9 o'clock direction. And, as shown in FIG. 4, the movable element 5 is lowered, and the contact point P is at the upper part of the gear 9, that is, in the 12 o'clock direction. Finally, in FIG. 5, the movable element 5 is shifted to the left, and the contact point P is to the right of the gear 9, that is, in the 3 o'clock direction. Each time moving on from one figure to the next, the movable element 5 makes an orbital movement of a quarter turn. The second flexible connection blades 11, 12 of the two translation stages 24, 25, the third flexible blades 31, 32, 33, 34, and the flexible blades of the resonators 6, 7 bend according to the direction in which the movable element 5 moves. Also, the pendulum 20 follows the following movement. They vibrate sinusoidally such that there is a 90° phase shift between each of the resonators 6, 7.

[0069] The rotor 3 and the movable element 5 form what is generally known in mechanical engineering as a "harmonic gearbox". For example, the tooth row 10 of the rotor 3 has 56 teeth, and the tooth row 12 of the movable element 5 has 60 teeth. The deceleration factor between the speed of the contact point and the speed of the rotor is given by r = (Z m - Z r ) / Z r . Here, Z m represents the number of teeth of the movable element 5, and Z r represents the number of teeth of the rotor 3. Thus, in this example, r = (60 - 56) / 56 = 1 / 14. This deceleration is advantageous because it can be directly mounted on the motor and reduce the number of additional reduction gears required, for example, to drive the needle.

[0070] Preferably, at least one tooth of the tooth row 10 of the rotor 3 contacts the tooth row 12 of the movable element 5 to transmit the movement. Thus, this eliminates the risk of the rotor 3 stopping. The movable element 5 and the rotor 3 can have dimensions such that at least one tooth of the tooth row 10 contacts the tooth row 12 of the rotor 3.

[0071] Preferably, the amplitude of the alternating voltage applied to the resonators 6, 7 capable of vibrating the movable element 5 is variable in order to make the vibration of the movable element 5 perfectly circular, which aims to compensate for any ellipticity of unwanted trajectories and also aims to increase the efficiency of the motor 1.

[0072] The electrical signals applied to each of the two resonators 6, 7 are preferably sinusoidal and have a 90° phase difference. When one of the amplitudes is at its maximum, the other is zero, and vice versa.

[0073] If the rotor 3 is to rotate in the other direction, simply reverse the sign of the phase shift of the voltage applied to the resonators 6, 7. Thus, due to the vibration of the pendulum 20, the movable element 5 of the stator 2 rotates in the other direction. When actuating the needle display, this makes it possible to adjust the position of the needle in both directions.

[0074] In the case of a portable watch, the resonant frequency or natural frequency of each of the resonators 6, 7 of the piezoelectric motor 1 is adapted to match the frequency of the crystal used to adjust the rate of the movement. By operating at the resonant frequency, a reasonable amplitude is obtained for a given power consumption.

[0075] Not only the excitation frequency corresponding to the resonant frequency, but also the excitation frequencies corresponding to the divisors of the frequency of the crystal, which is usually 32764 Hz, are selected. For example, frequencies of 128 Hz or 256 Hz are selected. The vibration frequency of the motor 1 is preferably adjusted and tuned to the excitation frequency such that its vibration amplitude does not fall below 90 - 95% of the maximum amplitude at resonance.

[0076] The vibration frequency is adapted by changing the mass of the movable element 5 and / or the stiffness of the flexible blade. For example, a ring can be assembled under the movable element 5, thereby making it heavier and lowering the vibration frequency. The ring not shown preferably comprises, for example, nickel silver throughout.

[0077] In addition, in order to precisely lower the frequency, micro-stitching of the adhesive can also be added.

[0078] Also, for example, by using a laser or by milling to remove material from the elastic elements to reduce their rigidity, the frequency can also be lowered.

[0079] To increase the frequency, for example, by using a laser or milling to remove material, the mass of the movable element 5 can be made lighter. Since very precise adjustment is possible by these methods, it is preferably used for tuning the motor to the crystal.

[0080] Since the resonators 6, 7 are microfabricated, small inertial blocks can also be removed during fabrication to increase the frequency to the target value.

[0081] The resonance peak of the motor connected to the load has a magnitude that is sufficiently large, much larger than that of the crystal. This is the reason why the speed of the motor can be varied by changing its excitation frequency without much loss of amplitude, thereby compensating for, for example, the loss of state after being impacted or any other arbitrary interference, and realigning the crystal time base to the needle position.

[0082] According to the present invention, the two resonators 6, 7 are arranged with respect to the movable element 5 such that the torque due to all the accelerating forces applied in the plane of each resonator 6, 7 is zero.

[0083] This advantage is achieved by the configuration of the piezoelectric motor described above.

[0084] For example, when suddenly accelerating horizontally to the right (along the axis X), the resonator 6, the movable element 5, and the pair of translation stages 24, 25 receive an accelerating force that tends to push them to the left.

[0085] The resonators 6, 7 are dimensioned and arranged relative to the movable element 5 such that the torque resulting from all the forces applied around the rotation center of the resonators 6, 7 is zero in the plane of each resonator 6, 7.

[0086] Therefore, the resonators 6, 7 can vibrate without being hindered by lateral impacts. The same applies to the direction of other impacts acting on the same resonators 6, 7 if the center of gravity of the resonators alone is located on a straight line passing through the pivot point.

[0087] FIG. 6 shows resonators 6, 7 such as those used in the piezoelectric motor of FIGS. 1 - 5. The resonator 6 includes a vibration weight 20 having a main arm, a first inertial block 44 at the first end, and a second inertial block 45 at the second end, and this second inertial block 45 forms an elbow that bends under the main arm.

[0088] The base 43 has the shape of a parallelepiped offset substantially straight towards the first inertial block 44, and its first corner faces towards the bent elbow of the second inertial block 45. The base 43 is disposed between the first inertial block 44 and the bent elbow of the second inertial block 45. The base 43 has an inclined channel 38 that opens from the first corner towards the inside of the base 43.

[0089] The resonator includes a flexible guide having a first flexible blade 36 that connects the vibration weight 20 to the base 43 from the end of the bent elbow, and the first flexible blade 36 extends within the inclined channel 38 to an attachment point at the bottom of the inclined channel 38.

[0090] The flexible guide includes a second flexible blade 37 that extends parallel to the arm of the vibration weight 20 from the first corner of the base 43 to an attachment point inside the bent elbow of the vibration weight 20. The second flexible blade 37 is disposed above the first flexible blade 36.

[0091] The first flexible blade 36 and the second flexible blade 37 form a "Y" shape and extend to form a non-zero angle within the range of 10° to 80°, preferably within the range of 30° to 60°, and more preferably within the range of 40° to 50°.

[0092] The two flexible blades 36, 37 contain a piezoelectric material. Here, it is disposed over the entire second flexible blade 37 and on a part of the first flexible blade 36. The flexible blades 36, 37 are actuated in the same manner as in the previous embodiment using electrical contacts (not shown).

[0093] For example, the flexible blade has a layer of piezoelectric material sandwiched between two electrode layers. These electrode layers are disposed on top of a monolithic structural support material such as single-crystal or polycrystalline silicon, such as quartz, glass, metal, etc.

[0094] To actuate the flexible blades 36, 37, the base 43 has a plurality of electrical contacts 9 connected to the electrode layers to receive current and actuate the piezoelectric layers of the flexible blades.

[0095] The piezoelectric layer preferably includes a crystalline or polycrystalline material, such as that of solid ceramics (in the case of sodium potassium niobate) or PZT-type ceramics (in the case of lead zirconate titanate), and the flexible blades 36, 37 have a thickness that allows their deformation.

[0096] Therefore, by electrically activating the layer of piezoelectric material, the flexible blades 36, 37 deform alternately laterally towards the center and outwards. This activation is generated by an alternating voltage. By actuating the piezoelectric layer, the flexible blades 36, 37 alternately bend slightly and straighten at a predetermined frequency.

[0097] By choosing to actuating the two flexible blades 36, 37 in opposite phases, the pendulum 20 performs small oscillations about the center of rotation corresponding to the point where the two flexible blades intersect. Thus, the pendulum 20 oscillates, and the two inertial blocks 44, 45 move laterally at a specific frequency.

[0098] The resonators 6, 7 according to the above method preferably mainly comprise single-crystalline or polycrystalline materials such as silicon, glass, ceramics, and metals.

[0099] The resonators 6, 7 are obtained, for example, by an optical lithography micromachining process of the MEMS (Micro-Electro-Mechanical System) type. The rigidity, elasticity, and machining accuracy of such materials improve the resonance quality of the resonators 6, 7.

[0100] Also, the non-magnetic and low conductivity properties of such materials provide excellent resistance to large DC and AC magnetic fields.

[0101] Also, the resonators 6, 7 are configured to vibrate the pendulum 20 at the natural vibration frequencies of the resonators 6, 7. In this way, the power consumption of the resonators is suppressed, especially by increasing the angular travel of the pendulum.

[0102] Of course, other types of resonators are possible, such as RCC, double RCC, and helical type resonators. Examples of piezoelectric resonators are described in European patent applications EP22216410.5, EP22216418.8, and EP22216423.8.

[0103] It will be understood that various changes and / or improvements and / or combinations obvious to those skilled in the art can be made to the various embodiments of the present invention without departing from the scope of the present invention as defined by the appended claims.

Claims

**Claim 1**: A rotary piezoelectric motor (1) for a timer, comprising: a rotor (3) configured to rotate and actuate a mechanical device; a stator (2) provided with a piezoelectric actuator and configured to rotate the rotor (3); the piezoelectric actuator includes a movable element (5) that rotates the rotor (3) in a first direction by movement; the piezoelectric actuator has two electrically actuatable resonators (6, 7), and the two resonators (6, 7) consist of a first resonator (6) and a second resonator (7); the two resonators (6, 7) are connected to the movable element (5) to move the movable element (5) relative to the rotor (3) to rotate the rotor (3); the two resonators (6, 7) are arranged with respect to the movable element (5) to vibrate the movable element (5) in a first horizontal direction and a second vertical direction different from each other; the two resonators (6, 7) have a vibration weight (20) actuated by a pair of flexible blades (36, 37) containing a piezoelectric material characterized piezoelectric motor (1). **Claim 2**: The first resonator (6) and the second resonator (7) are arranged perpendicular to each other such that the first direction and the second direction are substantially perpendicular. The piezoelectric motor (1) according to claim 1, characterized in that. **Claim 3**: The first resonator (6) and the second resonator (7) are respectively arranged on different sides of the shape of the movable element (5), and these sides are adjacent to each other. The piezoelectric motor (1) according to claim 1, characterized in that. **Claim 4**: Comprising a first translation stage (24) that enables the movable element (5) to move in the first direction. The piezoelectric motor (1) according to claim 1, characterized in that. **Claim 5**: Comprising a second translation stage (25) that enables the movable element (5) to move in the second direction. The piezoelectric motor (1) according to claim 4, characterized in that. **Claim 6**: The second translation stage (25) is arranged in series with the first translation stage (24), and the movable element (5) is connected to the second translation stage (25). The piezoelectric motor (1) according to claim 5, characterized in that. **Claim 7**: The first translation stage (24) and the second translation stage (25) are substantially perpendicular to each other. The piezoelectric motor (1) according to claim 5, characterized in that...

8. A translation stage (24, 25) is arranged on the opposite side of the resonator (6, 7) with respect to the movable element (5). The piezoelectric motor (1) according to claim 1, characterized in that...

9. The movable element (5) performs an orbital motion that is circular in the second direction opposite to the first direction. The piezoelectric motor (1) according to claim 1, characterized in that...

10. The movable element (5) is always in contact with the rotor (3) while the piezoelectric motor (1) is operating. The piezoelectric motor (1) according to claim 1, characterized in that...

11. The rotor (3) rotates continuously due to the movement of the movable element (5). The piezoelectric motor (1) according to claim 9, characterized in that...

12. The movable element (5) is in the form of a ring, and the rotor (3) is arranged inside the ring. The piezoelectric motor (1) according to claim 1, characterized in that...

13. The movable rotor (3) and the movable element (5) are in contact inside the ring. The piezoelectric motor (1) according to claim 12, characterized in that...

14. The rotor (3) has a gear (9), and the ring has an inner tooth row (10) that engages with the outer tooth row (12) of the gear (9). The piezoelectric motor (1) according to claim 12, characterized in that...

15. The rotation of the movable element (5) with respect to the center of the movable element (5) is fixed. The piezoelectric motor (1) according to claim 1, characterized in that...

16. The first resonator (6) and the second resonator (7) are actuated so that their phases are shifted by 90°. The piezoelectric motor (1) according to claim 1, characterized in that...

17. A timepiece comprising a movement for a timepiece equipped with a gear transmission configured to rotate at least one needle, the piezoelectric motor (1) according to claim 1 being provided to actuate the gear transmission. Characterized in that it is a timepiece.

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