Noise reduction piezoelectric driving method and system and lens driving device

Abstract

The invention belongs to the technical field of piezoelectric driving, and particularly relates to a noise reduction piezoelectric driving method and system and a lens driving device. According to the noise reduction piezoelectric driving method, a square wave signal is adopted to drive a piezoelectric element; in a control period when the piezoelectric element is driven, the pulse amplitude of at least one pulse period is adjusted to be different from the pulse amplitudes of other pulse periods. According to the invention, a variable square wave driving mode is adopted, driving square waves for driving the piezoelectric element are regulated and controlled during starting and stopping, and the combination of different driving square waves is utilized, so that the speed and acceleration change rate of the piezoelectric element for starting and stopping movement are reduced, and the noise problem can be effectively improved.

Description

Technical Field

[0001] This invention belongs to the field of piezoelectric drive technology, specifically relating to a noise reduction piezoelectric drive method, system, and lens drive device. Background Technology

[0002] With the development of technology, many electronic devices today (such as smartphones or digital cameras) have the function of taking pictures or recording videos. The use of these electronic devices is becoming more and more common, and they are developing towards convenient and thinner designs to provide users with more choices.

[0003] Some electronic devices with photographic or video recording capabilities are equipped with lens drive mechanisms to move optical components such as lenses, thereby achieving functions such as autofocus, image stabilization, or aperture adjustment. Light can pass through the optical components and form an image on the photosensitive element. To achieve these functions, the Smooth Impact Drive Mechanism (SIDM) was developed. An SIDM is a drive mechanism that uses piezoelectric elements (piezoelectric motors) to drive moving parts to achieve purposes such as autofocus, image stabilization, or aperture adjustment.

[0004] Of course, in addition to lens driving devices, piezoelectric drive mechanisms can also be used in other fields that require linear displacement.

[0005] Currently, such as Figure 1 As shown, the piezoelectric element is mostly driven by a fixed-condition square wave drive mode, and the relationship between its carrier displacement (Stroke) and time (Time) is as follows. Figure 2 As shown. The moving part begins to move with the square wave drive signal and stops moving when the square wave drive signal stops. In the above-described fixed-condition square wave drive mode, the velocity and acceleration of the piezoelectric element change rapidly at the start and end of its movement, such as... Figure 3 and Figure 4 As shown, this leads to the problem of high noise during start-up and shutdown. Figure 5 The interval (A') represents the noise when the piezoelectric element starts moving, the interval (B') represents the noise when the piezoelectric element is moving steadily, and the interval (C') represents the noise when the piezoelectric element stops moving. It can be seen that the fixed-condition square wave driving mode can cause the peak-to-peak sound pressure level to reach 50 mPa.

[0006] How to achieve stable linear displacement while driving piezoelectric elements and reduce the noise generated during driving is a question that those skilled in the art need to actively consider. Summary of the Invention

[0007] The present invention addresses the above-mentioned technical problems by providing a noise reduction piezoelectric driving method, system, and lens driving device.

[0008] A noise-reducing piezoelectric driving method, wherein the noise-reducing piezoelectric driving method uses a square wave signal to drive the piezoelectric element;

[0009] During the control cycle of driving the piezoelectric element, the pulse amplitude of at least one pulse cycle is adjusted to be different from the pulse amplitude of other pulse cycles.

[0010] Optionally, a pulse period with a different pulse amplitude from other pulse periods is defined as the pulse period to be adjusted. There are at least two pulse periods to be adjusted, and the two pulse periods to be adjusted are adjacent or separated by at least one other pulse period. The pulse amplitudes of each pulse period to be adjusted are the same or different.

[0011] Optionally, a minimum pulse amplitude and a maximum pulse amplitude are preset, and within the control period, the pulse amplitude of each pulse cycle is randomly adjusted to a pulse amplitude between the minimum pulse amplitude and the maximum pulse amplitude.

[0012] Optionally, a minimum pulse amplitude and a maximum pulse amplitude are preset, and within the control period, the pulse amplitude of each pulse cycle is adjusted to gradually increase from the minimum pulse amplitude to the maximum pulse amplitude.

[0013] Optionally, a minimum pulse amplitude is preset, and within the control period, the pulse amplitude of each pulse period is adjusted to gradually increase from the minimum pulse amplitude.

[0014] Optionally, a minimum pulse amplitude is preset, and within the control period, the pulse amplitude of each pulse period is adjusted to gradually increase from the minimum pulse amplitude. The adjustment method is as follows:

[0015] Let the minimum pulse amplitude be A, then:

[0016] A i =A+n i n i ∈[0,∞] and i∈[1,m]∩Z

[0017] Among them, A i Let n be the pulse amplitude of the i-th pulse period. i is the pulse amplitude adjustment value, and m is the number of pulse cycles within the control cycle.

[0018] n i The preferred choice is an increasing sequence.

[0019] Optionally, a maximum pulse amplitude is preset, and within the control cycle, the pulse amplitude of each adjustment cycle is adjusted to gradually decrease from the maximum pulse amplitude. The adjustment method is as follows:

[0020] Let the maximum pulse amplitude be A', then:

[0021] A i =A'-n i n i ∈[0,∞] and i∈[1,m]∩Z

[0022] Among them, A i Let n be the pulse amplitude of the i-th pulse period. i is the pulse amplitude adjustment value, and m is the number of pulse cycles within the control cycle.

[0023] n i The preferred choice is an increasing sequence.

[0024] Optionally, the pulse amplitude of each pulse cycle is adjusted to gradually increase starting from the lowest pulse amplitude as follows:

[0025] Let the minimum pulse amplitude be A, then:

[0026] A i =A+(i-1)k, i∈[1,m]∩Z

[0027] Among them, A i Let be the pulse amplitude of the i-th pulse cycle, k be the pulse amplitude adjustment value greater than 0 and the unit of k is the same as A, and m be the number of pulse cycles within the control cycle.

[0028] Optionally, a minimum pulse amplitude and a maximum pulse amplitude are preset, and within the control period, the pulse amplitude of each pulse cycle is adjusted to gradually decrease from the maximum pulse amplitude to the minimum pulse amplitude.

[0029] Optionally, a maximum pulse amplitude is preset, and within the control period, the pulse amplitude of each pulse period is adjusted to gradually decrease from the maximum pulse amplitude.

[0030] Optionally, the pulse amplitude of each pulse cycle is adjusted to gradually decrease from the highest pulse amplitude as follows:

[0031] Let the maximum pulse amplitude be A', then:

[0032] A i =A'-(i-1)k, i∈[1,m]∩Z

[0033] Among them, A i Let be the pulse amplitude of the i-th pulse cycle, k be the pulse amplitude adjustment value greater than 0 and the unit of k is the same as A, and m be the number of pulse cycles within the control cycle.

[0034] Optionally, a minimum pulse amplitude is preset, and within the control cycle, the pulse amplitude of each pulse cycle is adjusted to gradually increase from the minimum pulse amplitude to half a control cycle, and then gradually decrease back to the minimum pulse amplitude.

[0035] Optionally, the pulse amplitude of each pulse cycle can be adjusted by gradually increasing from the lowest pulse amplitude to half a control cycle, and then gradually decreasing back to the lowest pulse amplitude.

[0036] Let the minimum pulse amplitude be A, then:

[0037]

[0038] and

[0039]

[0040] Among them, A i Let be the pulse amplitude of the i-th pulse cycle, k be the pulse amplitude adjustment value greater than 0 and the unit of k is the same as A, and m be the number of pulse cycles within the control cycle.

[0041] Optionally, a maximum pulse amplitude is preset, and within the control cycle, the pulse amplitude of each pulse cycle is adjusted to gradually decrease from the maximum pulse amplitude to half a control cycle, and then gradually increase to the maximum pulse amplitude.

[0042] Optionally, the pulse amplitude of each pulse cycle can be adjusted by gradually decreasing from the highest pulse amplitude to half a control cycle, and then gradually increasing back to the highest pulse amplitude.

[0043] Let the maximum pulse amplitude be A', then:

[0044]

[0045] and

[0046]

[0047] Among them, A i Let be the pulse amplitude of the i-th pulse cycle, k be the pulse amplitude adjustment value greater than 0 and the unit of k is the same as A, and m be the number of pulse cycles within the control cycle.

[0048] Optionally, the minimum pulse amplitude is 3V.

[0049] Optionally, the maximum pulse amplitude is 15V.

[0050] Optionally, the pulse amplitude of the square wave signal can be adjusted using PWM pulse width modulation.

[0051] Optionally, there is a pulse period with a pulse amplitude of zero between two adjacent control cycles.

[0052] A noise-reducing piezoelectric drive system, the noise-reducing piezoelectric drive system comprising:

[0053] The pulse amplitude adjustment module is used to adjust the pulse amplitude of at least one pulse cycle to be different from the pulse amplitude of other pulse cycles during the control cycle when the piezoelectric element is driven by a square wave signal.

[0054] A lens driving device includes a piezoelectric element. When the piezoelectric element is driven by a square wave signal, the noise reduction piezoelectric driving method provided by the present invention is used.

[0055] Optionally, the lens driving device includes:

[0056] Base;

[0057] A movable seat is rotatably mounted on the base about an axis, and a mounting hole is provided at the bottom end of the movable seat;

[0058] The driving mechanism employs a piezoelectric mechanism, which drives the movable seat to rotate around an axis. The piezoelectric mechanism includes a piezoelectric element, a friction rod, and a movable pin. The piezoelectric element is mounted on the base, and the friction rod is fixedly connected to the piezoelectric element. The friction rod is connected to the movable pin, which extends into the mounting hole. When the piezoelectric element moves, the friction rod performs linear motion, driving the movable pin to push the movable seat to rotate within the mounting hole.

[0059] Beneficial effects: The present invention has at least one or more of the following advantages:

[0060] This invention employs a variable square wave drive mode. By adjusting the driving square wave of the piezoelectric element during start-up and stop, and utilizing different combinations of driving square waves, the rate of change of speed and acceleration of the piezoelectric element at the start and end of its motion is reduced, which can effectively improve the noise problem. Attached Figure Description

[0061] Figure 1 This is a schematic diagram of a square wave signal in a fixed-condition square wave driving mode in the prior art;

[0062] Figure 2 To adopt Figure 1 A graph showing the relationship between carrier displacement (Stroke, ordinate, mm) and time (Time, abscissa, s) when a square wave signal drives a piezoelectric element.

[0063] Figure 3 To adopt Figure 1 A graph showing the relationship between velocity (vertical axis, mm / s) and time (horizontal axis, s) during the start-up and stop of a piezoelectric element driven by a square wave signal.

[0064] Figure 4 To adopt Figure 1 When a square wave signal drives a piezoelectric element, the acceleration during startup and shutdown is shown on the ordinate (mm / s²). 2 A graph showing the relationship between time (horizontal axis, unit: seconds);

[0065] Figure 5 To adopt Figure 1 A graph showing the relationship between sound pressure (vertical axis) and time (horizontal axis) at startup and shutdown when a square wave signal drives a piezoelectric element;

[0066] Figure 6 This is a schematic diagram of the square wave signal in the variable square wave driving mode of Embodiment 1 of the present invention;

[0067] Figure 7 To adopt Figure 6 A graph showing the relationship between carrier displacement (Stroke, ordinate, mm) and time (Time, abscissa, s) when a square wave signal drives a piezoelectric element.

[0068] Figure 8 To adopt Figure 6 A graph showing the relationship between velocity (vertical axis, mm / s) and time (horizontal axis, s) during the start-up and stop of a piezoelectric element driven by a square wave signal.

[0069] Figure 9 To adopt Figure 6 When a square wave signal drives a piezoelectric element, the acceleration during startup and shutdown is shown on the ordinate (mm / s²). 2 A graph showing the relationship between time (horizontal axis, unit: seconds);

[0070] Figure 10 To adopt Figure 6 A graph showing the relationship between sound pressure (vertical axis) and time (horizontal axis) at startup and shutdown when a square wave signal drives a piezoelectric element;

[0071] Figure 11 This is an exploded view of one structure of the lens driving device of the present invention;

[0072] Figure 12 for Figure 11 Exploded view of part of the structure;

[0073] Figure 13 for Figure 11 An exploded view of a medium-voltage electrical mechanism. Detailed Implementation

[0074] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, so as to better understand the purpose, features and advantages of the present invention. It should be understood that the embodiments shown in the drawings are not intended to limit the scope of the present invention, but are only for illustrating the essential spirit of the technical solution of the present invention.

[0075] In the following description, certain specific details are set forth for the purpose of illustrating various disclosed embodiments in order to provide a thorough understanding of the various disclosed embodiments. However, those skilled in the art will recognize that embodiments may be practiced without one or more of these specific details. In other instances, well-known apparatuses, structures, and techniques associated with this application may not have been shown or described in detail to avoid unnecessarily obscuring the description of the embodiments.

[0076] Throughout this specification, references to "an embodiment" or "an embodiment" indicate that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Therefore, the appearance of "in an embodiment" or "an embodiment" in various places throughout the specification does not necessarily refer to the same embodiment. Furthermore, a particular feature, structure, or characteristic may be combined in any manner in one or more embodiments.

[0077] In the following description, in order to clearly demonstrate the structure and working method of the present invention, a number of directional terms will be used. However, terms such as "front", "back", "left", "right", "outside", "inside", "outward", "inward", "up", and "down" should be understood as convenient terms and not as limiting terms.

[0078] This invention provides a noise-reducing piezoelectric driving method, which uses a square wave signal to drive the piezoelectric element. During the control cycle of driving the piezoelectric element, the pulse amplitude of at least one pulse cycle is adjusted to be different from the pulse amplitude of other pulse cycles.

[0079] For the square wave signal of this invention, it has one or more control cycles, and one control cycle typically has several pulse cycles. Several important parameters of a pulse cycle are pulse width, duty cycle, pulse frequency, and pulse amplitude. Pulse width refers to the duration of the pulse after it appears, and duty cycle is the ratio of pulse width to pulse period. Pulse frequency refers to the number of pulse cycles per second. For example, a pulse frequency of 1kHz means there are 1000 pulse cycles per second. The conversion between pulse period and pulse frequency is: pulse period = 1 / pulse frequency. Pulse amplitude is the maximum change in the pulse signal over time, that is, the voltage value in the high-level state.

[0080] When driving piezoelectric elements, this invention improves the traditional fixed-condition square wave driving mode to a variable square wave driving mode. Specifically, instead of the traditional square wave signal having the same pulse amplitude in each pulse cycle, this invention ensures that the pulse amplitude of at least one pulse cycle differs from the pulse amplitudes of other pulse cycles within the control cycle. By utilizing the difference in pulse amplitude of at least one pulse cycle, the rate of change of velocity and acceleration at the start and end of the piezoelectric element's motion is reduced, ultimately effectively improving the noise problem.

[0081] In practical implementation, the pulse period without pulse amplitude adjustment can be defined as the preset pulse period. The preset parameters of the pulse period without adjustment can be determined in advance. Of course, each preset parameter includes the preset pulse amplitude. The pulse amplitude of the pulse period that needs to be adjusted is adjusted to be different from the preset pulse amplitude, while other parameters remain the same.

[0082] Each preset parameter can be the same as the parameters in the traditional fixed-condition square wave drive mode, or each preset parameter can be predetermined according to actual needs.

[0083] In one embodiment, during a control cycle, at least one pulse cycle is defined as the pulse cycle to be adjusted, and the pulse amplitude of the pulse cycle to be adjusted is different from the pulse amplitude of other pulse cycles.

[0084] Where there are at least two pulse periods to be adjusted, then there are at least one other pulse period between the two pulse periods to be adjusted, and the pulse amplitudes of each pulse period to be adjusted are the same or different.

[0085] In this embodiment, there are two or more pulse cycles to be adjusted within the control cycle. Two adjacent pulse cycles to be adjusted are directly adjacent to each other, or they are separated by one or more other pulse cycles.

[0086] Within the control cycle, it is preferable that all pulse cycles are the pulse cycles to be adjusted.

[0087] In one embodiment, a minimum pulse amplitude and a maximum pulse amplitude are preset before driving the piezoelectric element.

[0088] During the control cycle when using a square wave signal to drive a piezoelectric element, the pulse amplitude of each pulse cycle is randomly adjusted to a value between the lowest and highest pulse amplitude, based on the premise that the pulse amplitudes of two adjacent pulse cycles are different.

[0089] In one embodiment, a minimum pulse amplitude and a maximum pulse amplitude are preset before driving the piezoelectric element.

[0090] During the control cycle when using a square wave signal to drive the piezoelectric element, the pulse amplitude of each pulse cycle is adjusted to gradually increase from the lowest pulse amplitude to the highest pulse amplitude.

[0091] In this embodiment, the pulse amplitude can be gradually increased from the lowest pulse amplitude to the highest pulse amplitude according to a preset increase rule. The preset increase rule can be, for example, a linear increase or an approximately linear increase, or a proportional increase, an arithmetic sequence, or other similar methods.

[0092] For example, the increase ratio P can be calculated based on the number of pulse cycles and the difference between the lowest and highest pulse amplitudes. 升高 This is to achieve a gradual increase in pulse amplitude:

[0093]

[0094] Where A' is the highest pulse amplitude, A is the lowest pulse amplitude, and m is the number of pulse cycles within the control cycle.

[0095] In one embodiment, a minimum pulse amplitude of A is preset before driving the piezoelectric element.

[0096] During the control cycle when using a square wave signal to drive the piezoelectric element, the pulse amplitude of each pulse cycle is adjusted to gradually increase from the lowest pulse amplitude.

[0097] In one embodiment, within a control period, the pulse amplitude of each pulse period is adjusted to the following condition, provided that the pulse amplitude of at least one pulse period differs from that of other pulse periods:

[0098] Let the minimum pulse amplitude be A, then:

[0099] A i =A+n i n i ∈[0,∞] and i∈[1,m]∩Z

[0100] Among them, A i Let n be the pulse amplitude of the i-th pulse period. iis the pulse amplitude adjustment value, and m is the number of pulse cycles within the control cycle.

[0101] n i Preferably, an increasing sequence / function starting from n1 is used, so that the pulse amplitude of each pulse period is adjusted to gradually increase within the control period.

[0102] In one embodiment, adjusting the pulse amplitude of each pulse cycle to gradually increase from the lowest pulse amplitude can be achieved by increasing it according to a preset increase rule. The preset increase rule can be, for example, a linear or approximately linear increase, or a proportional increase.

[0103] Preferably, the increase method of the present invention is to adjust the pulse amplitude of each pulse period starting from the pulse period where the lowest pulse amplitude is located according to the following increase rule:

[0104] A, A+k, A+2k, A+3k……A+(m-1)k

[0105] Therefore, the following formula can be obtained:

[0106] A i =A+(i-1)k, i∈[1,m]∩Z

[0107] Among them, A i Let be the pulse amplitude of the i-th pulse cycle, k be the pulse amplitude adjustment value greater than 0 and the unit of k is the same as A, and m be the number of pulse cycles within the control cycle.

[0108] The value of k is preferably an integer, such as 1, 2, 3, etc.

[0109] In one embodiment, a minimum pulse amplitude and a maximum pulse amplitude are preset before driving the piezoelectric element.

[0110] During the control cycle when using a square wave signal to drive the piezoelectric element, the pulse amplitude of each pulse cycle is adjusted to gradually decrease from the highest pulse amplitude to the lowest pulse amplitude.

[0111] In this embodiment, the pulse amplitude can be gradually reduced from the highest pulse amplitude by following a preset reduction rule to the lowest pulse amplitude. The preset reduction rule can be, for example, a linear or approximately linear reduction, or a proportional reduction, an arithmetic sequence, or similar methods.

[0112] For example, the reduction ratio P can be calculated based on the number of pulse cycles and the difference between the lowest and highest pulse amplitudes. 降低 This is to achieve a gradual reduction in pulse amplitude:

[0113]

[0114] Where A' is the highest pulse amplitude, A is the lowest pulse amplitude, and m is the number of pulse cycles within the control cycle.

[0115] In one embodiment, the maximum pulse amplitude is preset to A' before driving the piezoelectric element.

[0116] During the control cycle when using a square wave signal to drive the piezoelectric element, the pulse amplitude of each pulse cycle is adjusted to gradually decrease starting from the highest pulse amplitude.

[0117] In one embodiment, within a control cycle, the pulse amplitude of each adjustment cycle is adjusted to the following condition, provided that the pulse amplitude of at least one pulse cycle differs from that of other pulse cycles:

[0118] Let the maximum pulse amplitude be A', then:

[0119] A i =A'-n i n i ∈[0,∞] and i∈[1,m]∩Z

[0120] Among them, A i Let n be the pulse amplitude of the i-th pulse period. i is the pulse amplitude adjustment value, and m is the number of pulse cycles within the control cycle.

[0121] n i Preferably, an increasing sequence / function starting from n1 is used, so that the pulse amplitude of each pulse period is adjusted to gradually decrease within the control period.

[0122] In one embodiment, adjusting the pulse amplitude of each pulse cycle to gradually decrease from the highest pulse amplitude can be achieved by following a preset reduction rule. This preset reduction rule could be a linear or near-linear reduction, or a proportional reduction.

[0123] Preferably, the reduction method of the present invention is to adjust the pulse amplitude of each pulse period starting from the pulse period where the highest pulse amplitude is located according to the following reduction rule:

[0124] A', A'-k, A'-2k, A'-3k...A'-(m-1)k

[0125] Therefore, the following formula can be obtained:

[0126] A i =A'-(i-1)k, i∈[1,m]∩Z

[0127] Among them, A iLet be the pulse amplitude of the i-th pulse cycle, k be the pulse amplitude adjustment value greater than 0 and the unit of k is the same as A, and m be the number of pulse cycles within the control cycle.

[0128] The value of k is preferably an integer, such as 1, 2, 3, etc.

[0129] In one embodiment, a minimum pulse amplitude A is preset before driving the piezoelectric element.

[0130] When using a square wave signal to drive a piezoelectric element, the pulse amplitude of each pulse cycle is adjusted to gradually increase from the lowest pulse amplitude to half a control cycle, and then gradually decrease back to the lowest pulse amplitude.

[0131] In this embodiment, the pulse amplitude can be gradually increased from the lowest pulse amplitude by increasing it according to a preset increase pattern up to half a control cycle. The preset increase pattern can be, for example, a linear increase, an approximately linear increase, or a proportional increase.

[0132] Similarly, the pulse amplitude can be gradually reduced after increasing to half a control cycle by following a preset reduction pattern to the minimum pulse amplitude. This preset reduction pattern could be a linear or near-linear reduction, or a proportional reduction.

[0133] Preferably, the preset decreasing pattern adopts the same method as the preset increasing pattern to achieve a gradual decrease in pulse amplitude.

[0134] In addition, in scenarios where the pulse amplitude of each pulse cycle within the control period has both an increasing and decreasing trend, when the number of pulse cycles m within the control period is odd, the pulse amplitude of the middle pulse cycle is the highest; when the number of pulse cycles m within the control period is even, the pulse amplitudes of the two middle pulse cycles are the same and the highest.

[0135] In one embodiment, the pulse amplitude of each pulse cycle is adjusted by gradually increasing from the lowest pulse amplitude to half a control cycle, and then gradually decreasing back to the lowest pulse amplitude.

[0136] A, A+k, A+2k, A+3k...A+3k, A+2k, A+k, A

[0137] Therefore, the following formula can be obtained:

[0138]

[0139] and

[0140]

[0141] Among them, Ai Let be the pulse amplitude of the i-th pulse cycle, k be a pulse amplitude adjustment value greater than 0 with the same unit as A, and m be the number of pulse cycles within the control cycle. for Rounding up, Z indicates that i is an integer.

[0142] In one embodiment, the maximum pulse amplitude A' is preset before driving the piezoelectric element.

[0143] When using a square wave signal to drive a piezoelectric element, the pulse amplitude of each pulse cycle is adjusted to gradually decrease from the highest pulse amplitude to half a control cycle, and then gradually increase back to the highest pulse amplitude.

[0144] In this embodiment, the pulse amplitude can be gradually reduced from its highest value to half a control cycle according to a preset reduction rule. This preset reduction rule could be a linear or near-linear reduction, or a proportional reduction.

[0145] Similarly, the pulse amplitude can be gradually increased after decreasing to half a control cycle, or it can be increased to the maximum pulse amplitude according to a preset increase rule. The preset increase rule can be, for example, a linear increase or an approximately linear increase, or a proportional increase.

[0146] Preferably, the preset increase rule adopts the same method as the preset decrease rule to achieve a gradual increase in pulse amplitude.

[0147] In addition, in scenarios where the pulse amplitude of each pulse cycle within the control period has both a decreasing and increasing trend, when the number of pulse cycles m within the control period is odd, the pulse amplitude of the middle pulse cycle is the lowest; when the number of pulse cycles m within the control period is even, the pulse amplitudes of the two middle pulse cycles are the same and the lowest.

[0148] In one embodiment, the pulse amplitude of each pulse cycle is adjusted by gradually decreasing from the highest pulse amplitude to half a control cycle, and then gradually increasing back to the highest pulse amplitude.

[0149] A', A'-k, A'-2k, A'-3k...A'-3k, A'-2k, A'-k, A'

[0150] Therefore, the following formula can be obtained:

[0151]

[0152] and

[0153]

[0154] Among them, A i Let be the pulse amplitude of the i-th pulse cycle, k be a pulse amplitude adjustment value greater than 0 with the same unit as A, and m be the number of pulse cycles within the control cycle. for Rounding up, Z indicates that i is an integer.

[0155] In one embodiment, the minimum pulse amplitude is 3V.

[0156] In one embodiment, the maximum pulse amplitude is 15V.

[0157] In one embodiment, PWM pulse width modulation is used to adjust the pulse amplitude of the square wave signal.

[0158] In one embodiment, there is a pulse period with a pulse amplitude of zero between two adjacent control cycles.

[0159] This invention provides a noise-reducing piezoelectric drive system, which includes:

[0160] The pulse amplitude adjustment module is used to adjust the pulse amplitude of at least one pulse cycle to be different from the pulse amplitude of other pulse cycles during the control cycle when the piezoelectric element is driven by a square wave signal.

[0161] This invention provides a lens driving device, which includes a piezoelectric element. When driving the piezoelectric element with a square wave signal, the noise reduction piezoelectric driving method provided in the above embodiments is used.

[0162] In one embodiment, reference is made to Figure 11 and Figure 12 The lens drive mechanism is mounted on the lens to adjust the aperture size. The lens drive mechanism includes a base 10, a movable seat 20, and a drive mechanism 40.

[0163] The base 10 is used to fix it to the housing of the lens motor.

[0164] The movable base 20 is rotatably mounted on the base 10 around an axis. Both the movable base 20 and the base 10 have a lens clearance hole 50 along their axis, which mates with the lens on the lens motor, allowing light to enter the lens. The lens clearance hole 50 is typically circular. The lens clearance hole 50 is located at the center of the movable base 20 and the base 10, and this axis is the center line of the combined base 10 and movable base 20, which is also the axis of the lens clearance hole 50. Figure 12 Centerline A in the vertical direction.

[0165] The bottom of the movable base 20 is provided with mounting holes.

[0166] The drive mechanism 40 drives the movable seat 20 to rotate around the axis. (See reference...) Figures 11 to 13 The drive mechanism 40 adopts a piezoelectric mechanism, which includes a piezoelectric element 41, a friction rod 42, and a movable pin 43. The piezoelectric element 41 is mounted on the base 10. The friction rod 42 is fixedly connected to the piezoelectric element 41 and connected to the movable pin 43. The movable pin 43 extends into the mounting hole. When the piezoelectric element 41 moves, the friction rod 42 moves linearly, driving the movable pin 43 to push the movable seat 20 to rotate within the mounting hole 21.

[0167] The driving mechanism 40 of this invention employs a piezoelectric mechanism. When the piezoelectric element 41 is energized, it stretches, causing the friction rod 42 to move linearly. This, in turn, drives the movable seat 20 to rotate via the mounting hole 21 at the bottom of the movable seat 20 through the movable pin 43, thus achieving the rotational movement of the movable seat 20. Compared to traditional drive devices using a magnet and coil combination, where the magnet and coil generate a magnetic field that may interfere with other electronic components inside the phone, the piezoelectric mechanism avoids interference with other components such as the lens motor. Furthermore, the piezoelectric mechanism has a simple and compact overall structure, reducing the overall size of the lens driving device.

[0168] In one embodiment, the piezoelectric mechanism further includes a collar 44, a plug plate 45, and a movable member 46. The collar 44 is sleeved on the outside of the friction rod 42. The collar 44 is an open collar, and plug plates 45 are respectively provided at the two open ends of the collar 44. The plug plates 45 are inserted into the plug holes 461 of the movable member 46 and clamp the friction rod 42. The movable pin 43 is provided on the movable member 46.

[0169] With the above design, the movable pin 43 is indirectly connected to the friction rod 42. When the friction rod 42 moves with the piezoelectric element 41, the movable member 46 also moves linearly, causing the movable pin 43 at the top of the movable member 46 to push the movable seat 20 to rotate in the mounting hole 21 at the bottom of the movable seat 20, thereby realizing the rotation of the movable seat 20.

[0170] The insertion hole 461 adopts a T-shaped insertion hole, and the bottom of the insertion hole 461 is an open structure. The inner wall shape of the insertion hole 461 matches the opening of the insertion plate 45 and the collar 44 to which it is inserted.

[0171] Of course, the connection between the movable pin 43 and the friction rod 42 can also be achieved by other structures, as long as it can drive the movable pin 43 to push the movable seat 20 to rotate in the mounting hole 21 when the friction rod 42 moves in a straight line.

[0172] In one embodiment, the piezoelectric mechanism further includes a counterweight 47, which is fixedly connected to the piezoelectric element 41 and located on the side away from the friction rod 42. The counterweight 47 is mounted on the base 10, and the piezoelectric element 41 is disposed on the base 10 via the counterweight 47.

[0173] The counterweight 47, the piezoelectric element 41, and the friction rod 42 are stacked sequentially along the linear motion direction of the friction rod 42.

[0174] In one embodiment, reference is made to Figure 11 and Figure 12 The lens drive mechanism includes several blades 30, which are arranged circumferentially around the lens clearance aperture 50 and located above the base 10 and the movable seat 20. The radially outer sides of the blades 30 are rotatably connected to the base 10 in a direction parallel to the axis. The blades 30 are arranged in a ring shape, and their radially inner sides form an adjustable aperture adjustment aperture 30a. The movable seat 20 is connected to each blade 30. The drive mechanism 40 drives the movable seat 20 to rotate around the axis, thereby causing the blades 30 to rotate. As the blades 30 rotate, their radially inner sides move away from or closer to the axis, causing the diameter of the aperture adjustment aperture 30a to gradually increase or decrease. Because the opening size of the aperture adjustment aperture 30a changes, the light entering the lens changes accordingly, thus achieving lens obstruction and aperture adjustment.

[0175] In one embodiment, a fixing hole is provided on the radially outer side of the blade 30.

[0176] The base 10 is provided with a support protrusion 12, and the movable seat 20 is arranged around the outside of the support protrusion 12. The top of the support protrusion 12 is provided with a fixing pin 13, which is rotatably connected to the fixing hole, so that the radial outer side of the blade 30 is rotatably connected to the support protrusion 12 of the base 10 around the axial direction (that is, the up and down direction) of the fixing pin 13.

[0177] The number of fixing pins 13 is not less than the number of blades 30, so that one blade 30 can be rotatably connected to a corresponding fixing pin 13. For example, when there are six blades 30, the number of fixing pins 13 is also six.

[0178] Several fixed pins 13 are preferably evenly arranged circumferentially at the top of the support protrusion 12.

[0179] The fixing hole is a circular hole that rotatably connects with the fixing pin 13.

[0180] In one embodiment, the blade 30 is provided with a movable hole, and the top of the movable seat 20 is provided with a movable pin 22. The movable pin 22 is connected to the movable hole on the blade 30. When the movable seat 20 rotates, the movable pin 22 drives the blade 30 to rotate around a direction parallel to the axis, thereby causing the diameter of the aperture adjustment hole 30a to change.

[0181] The number of movable pins 22 is not less than the number of blades 30, so that one blade 30 can be connected to a corresponding movable pin 22. For example, when there are six blades 30, the number of movable pins 22 is also six.

[0182] A number of movable pins 22 are preferably evenly arranged circumferentially at the top of the movable seat 20.

[0183] In one embodiment, the base 10 has a plurality of fixed protrusions 14 arranged circumferentially along its edge. The fixed protrusions 14 are located outside the movable seat 20, and a fixed post 15 is provided at the top of the fixed protrusions 14.

[0184] The lens driving device also includes a top cover 70, which is fixedly connected to the fixing post 15, and forms a movable space between the top cover 70 and the base 10. The top cover 70, the movable seat 20 and the base 10 are provided with lens clearance holes 50 along the axis to cooperate with the lens. That is to say, the top cover 70 also has a top cover hole in the middle, and the diameter of the top cover hole is not smaller than the diameter of the lens clearance hole 50.

[0185] The movable seat 20, several blades 30 and the drive mechanism 40 are all arranged in the movable space, and the movable seat 20 and several blades 30 can rotate in the movable space.

[0186] One or more fixing posts 15 at the top of the fixing protrusion 14 can be set as needed.

[0187] The above embodiments of the present invention provide a piezoelectric element applied to a lens driving device for adjusting lens aperture. Of course, the piezoelectric element of the present invention can also be used in other piezoelectric driving scenarios, such as lens zoom and image stabilization, to achieve noise reduction during movement.

[0188] Example 1:

[0189] Before driving the piezoelectric element, the minimum pulse amplitude A = 3V is preset.

[0190] When using a square wave signal to drive a piezoelectric element, the pulse amplitude of each pulse cycle is adjusted to gradually increase from the lowest pulse amplitude to half a control cycle, and then gradually decrease back to the lowest pulse amplitude.

[0191] like Figure 6 The diagram shows two control cycles of a square wave signal, where the horizontal axis represents the time parameter in seconds (s) and the vertical axis represents the voltage parameter in volts (V). Each control cycle has 9 pulse periods. The pulse amplitude of each pulse period within the control cycle is adjusted as follows:

[0192] 3V, 6V, 9V, 12V, 15V, 12V, 9V, 6V, 3V;

[0193] In this embodiment, the other parameters of each pulse period are the same as those of the traditional fixed-condition square wave drive mode.

[0194] This embodiment adjusts the traditional fixed-condition square wave driving mode to a variable square wave driving mode, where the displacement of the piezoelectric element changes with time as follows: Figure 7 The movement process shown is related to Figure 2 In contrast, the displacement of piezoelectric elements changes gradually. For example... Figure 8 and Figure 9 As shown, this reduces the rate of change of velocity and acceleration of the piezoelectric element at the start and end of its motion. Because the changes in velocity and acceleration are slow during the starting and stopping phases, therefore... Figure 10 As shown, interval (A) represents the noise when the piezoelectric element starts moving, interval (B) represents the noise when the piezoelectric element is moving steadily, and interval (C) represents the noise when the piezoelectric element stops moving. It can be seen that the variable square wave driving mode results in a sound pressure peak value of about 10 mPa, which is significantly lower than the traditional fixed condition square wave driving mode.

[0195] In the above embodiments of the present invention, the number of decimal places to be retained for each parameter of infinite decimals can be predetermined and controlled.

[0196] Figure 6 In this control cycle, the pulse amplitude of each pulse cycle can be considered as follows: the pulse amplitude of the pulse cycle for which no pulse amplitude adjustment is performed is predetermined to be 3V. Within the control cycle, there are 7 pulse cycles to be adjusted, including those with the same pulse amplitude and those with different pulse amplitudes. Alternatively, the pulse amplitude of the pulse cycle for which no pulse amplitude adjustment is performed can be considered as 6V. Of course, the pulse amplitude of the pulse cycle for which no pulse amplitude adjustment is performed can also be considered as 9V, etc.

[0197] In other embodiments, the pulse periods described above can be shuffled or adjusted, for example:

[0198] 6V, 3V, 9V, 15V, 12V, 12V, 6V, 9V, 3V;

[0199] Of course, the pulse amplitude of each pulse cycle can also be other values, as long as the pulse amplitude of at least one pulse cycle is different from the pulse amplitude of other pulse cycles within the control period.

[0200] The preferred embodiments of the present invention have been described in detail above. However, it should be understood that after reading the above teachings, those skilled in the art can make various alterations or modifications to the present invention. These equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A noise-reducing piezoelectric drive method, characterized in that, The noise reduction piezoelectric driving method uses a square wave signal to drive the piezoelectric element; During the control cycle of driving the piezoelectric element, the pulse amplitude of at least one pulse cycle is adjusted to be different from the pulse amplitude of other pulse cycles.

2. The noise reduction piezoelectric drive method as described in claim 1, characterized in that, A pulse period with a different pulse amplitude from other pulse periods is defined as a pulse period to be adjusted. There are at least two pulse periods to be adjusted. The two pulse periods to be adjusted are adjacent to or separated by at least one other pulse period. The pulse amplitudes of each pulse period to be adjusted are the same or different.

3. The noise reduction piezoelectric drive method as described in claim 1 or 2, characterized in that, A minimum pulse amplitude is preset. Within the control cycle, the pulse amplitude of each pulse cycle is adjusted to gradually increase from the minimum pulse amplitude. The adjustment method is as follows: Let the minimum pulse amplitude be A, then: A i = A + n i ,n i ∈[0,∞]andi∈[1,m]∩Z Among them, A i Let n be the pulse amplitude of the i-th pulse period. i is the pulse amplitude adjustment value, and m is the number of pulse cycles within the control cycle.

4. The noise reduction piezoelectric drive method as described in claim 3, characterized in that, n i It is an increasing sequence.

5. The noise reduction piezoelectric drive method as described in claim 1 or 2, characterized in that, A maximum pulse amplitude is preset. Within the control cycle, the pulse amplitude of each adjustment cycle is adjusted to gradually decrease from the maximum pulse amplitude. The adjustment method is as follows: Let the maximum pulse amplitude be A', then: A i = A’ - n i , n i ∈ [0, ∞] and i ∈ [1, m] ∩ Z Among them, A i Let n be the pulse amplitude of the i-th pulse period. i is the pulse amplitude adjustment value, and m is the number of pulse cycles within the control cycle.

6. The noise reduction piezoelectric drive method as described in claim 5, characterized in that, n i It is an increasing sequence.

7. The noise reduction piezoelectric drive method as described in claim 1 or 2, characterized in that, A minimum pulse amplitude and a maximum pulse amplitude are preset. Within the control cycle, the pulse amplitude of each pulse cycle is randomly adjusted to a pulse amplitude between the minimum pulse amplitude and the maximum pulse amplitude. Alternatively, a minimum pulse amplitude and a maximum pulse amplitude are preset, and within the control cycle, the pulse amplitude of each pulse cycle is adjusted to gradually increase from the minimum pulse amplitude to the maximum pulse amplitude. Alternatively, a minimum pulse amplitude can be preset, and within the control period, the pulse amplitude of each pulse period can be adjusted to gradually increase from the minimum pulse amplitude. Alternatively, a minimum pulse amplitude and a maximum pulse amplitude are preset, and within the control period, the pulse amplitude of each pulse cycle is adjusted to gradually decrease from the maximum pulse amplitude to the minimum pulse amplitude. Alternatively, a maximum pulse amplitude can be preset, and within the control period, the pulse amplitude of each pulse period can be adjusted to gradually decrease from the maximum pulse amplitude. Alternatively, a minimum pulse amplitude is preset, and within the control cycle, the pulse amplitude of each pulse cycle is adjusted to gradually increase from the minimum pulse amplitude to half a control cycle, and then gradually decrease to the minimum pulse amplitude. Alternatively, a maximum pulse amplitude can be preset, and within the control cycle, the pulse amplitude of each pulse cycle can be adjusted to gradually decrease from the maximum pulse amplitude to half a control cycle, and then gradually increase back to the maximum pulse amplitude.

8. The noise reduction piezoelectric drive method as described in claim 1 or 2, characterized in that, A minimum pulse amplitude is preset. Within the control cycle, the pulse amplitude of each pulse cycle is adjusted to gradually increase from the minimum pulse amplitude. The adjustment method is as follows: Let the minimum pulse amplitude be A, then: A i =A+(i-1)k,i∈[1,m]∩Z Among them, A i Let be the pulse amplitude of the i-th pulse cycle, k be the pulse amplitude adjustment value greater than 0 and the unit of k is the same as A, and m be the number of pulse cycles in the control cycle. or, A minimum pulse amplitude is preset. Within the control cycle, the pulse amplitude of each pulse cycle is adjusted to gradually increase from the minimum pulse amplitude to half a control cycle, and then gradually decrease back to the minimum pulse amplitude. The adjustment method is as follows: Let the minimum pulse amplitude be A, then: and Among them, A i Let be the pulse amplitude of the i-th pulse cycle, k be the pulse amplitude adjustment value greater than 0 and the unit of k is the same as A, and m be the number of pulse cycles within the control cycle.

9. The noise reduction piezoelectric drive method as described in claim 8, characterized in that, The minimum pulse amplitude is 3V.

10. The noise reduction piezoelectric drive method as described in claim 1 or 2, characterized in that, A maximum pulse amplitude is preset. Within the control period, the pulse amplitude of each pulse period is adjusted to gradually decrease from the maximum pulse amplitude. The adjustment method is as follows: Let the maximum pulse amplitude be A', then: A i =A’-(i-1)k,i∈[1,m]∩Z Among them, A i Let be the pulse amplitude of the i-th pulse cycle, k be the pulse amplitude adjustment value greater than 0 and the unit of k is the same as A, and m be the number of pulse cycles in the control cycle. or, A maximum pulse amplitude is preset. Within the control cycle, the pulse amplitude of each pulse cycle is adjusted to gradually decrease from the maximum pulse amplitude to half a control cycle, and then gradually increase back to the maximum pulse amplitude. The adjustment method is as follows: Let the maximum pulse amplitude be A', then: and Among them, A i Let be the pulse amplitude of the i-th pulse cycle, k be the pulse amplitude adjustment value greater than 0 and the unit of k is the same as A, and m be the number of pulse cycles within the control cycle.

11. The noise reduction piezoelectric driving method as described in claim 10, characterized in that, The maximum pulse amplitude is 15V.

12. The noise reduction piezoelectric drive method as described in claim 1 or 2, characterized in that, The pulse amplitude of the square wave signal is adjusted using PWM pulse width modulation. And / or, there is a pulse period with a pulse amplitude of zero between two adjacent control cycles.

13. A noise-reducing piezoelectric drive system, characterized in that, The noise-reducing piezoelectric drive system includes: The pulse amplitude adjustment module is used to adjust the pulse amplitude of at least one pulse cycle to be different from the pulse amplitude of other pulse cycles during the control cycle when the piezoelectric element is driven by a square wave signal.

14. A lens driving device, the lens driving device comprising a piezoelectric element, characterized in that, When driving the piezoelectric element with a square wave signal, the noise reduction piezoelectric driving method described in any one of claims 1 to 12 is used.

15. The lens driving device as claimed in claim 14, characterized in that, The lens driving device includes: Base; A movable seat is rotatably mounted on the base about an axis, and a mounting hole is provided at the bottom end of the movable seat; The driving mechanism employs a piezoelectric mechanism, which drives the movable seat to rotate around an axis. The piezoelectric mechanism includes a piezoelectric element, a friction rod, and a movable pin. The piezoelectric element is mounted on the base, and the friction rod is fixedly connected to the piezoelectric element. The friction rod is connected to the movable pin, which extends into the mounting hole. When the piezoelectric element moves, the friction rod performs linear motion, driving the movable pin to push the movable seat to rotate within the mounting hole.

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