A vibration control system for ultrasonic cleaning of camera lenses

Abstract

This invention discloses a vibration control system for ultrasonic cleaning of camera lenses, relating to the field of vibration control technology for ultrasonic cleaning. The system includes: acquiring an electrical response signal; constructing transient sound field distribution description data for the lens lens during the current cleaning cycle based on the electrical response signal; identifying unwanted sound field aggregation node regions based on the transient sound field distribution description data, and determining their spatial locations and vibration energy concentration levels; generating an inverse phase compensation drive signal based on the identified spatial locations and vibration energy concentration levels of the unwanted sound field aggregation node regions; and superimposing the inverse phase compensation drive signal onto the drive signal. After the cleaning cycle ends, based on cleaning uniformity, when the cleaning uniformity does not meet expectations, adjusting the starting frequency and sweep step size of the frequency sweep excitation in the next cleaning cycle. Inverse phase compensation selectively suppresses areas with excessively high local energy without affecting the overall cleaning capability, effectively improving sound field uniformity.

Description

Technical Field

[0001] This invention relates to the field of vibration control technology for ultrasonic cleaning, specifically a vibration control system for ultrasonic cleaning of camera lenses. Background Technology

[0002] Camera lenses are widely used in outdoor security, vehicle assistance, and industrial monitoring. Their front-end light-transmitting film is directly exposed to the environment, making it susceptible to the accumulation of contaminants such as rainwater, mud, oil, and insect residue, leading to decreased image clarity. Ultrasonic cleaning technology utilizes piezoelectric transducers to excite high-frequency mechanical vibrations on the surface of the light-transmitting film, causing the attached contaminants to peel off or atomize under inertial force. This is a non-contact, chemical-free cleaning method that can be integrated into the lens module.

[0003] Existing methods typically use a fixed frequency or a simple frequency sweep to drive the piezoelectric transducer, exciting the light-transmitting sheet through a preset driving voltage and frequency sweep range. In existing methods, the acoustic resonance characteristics of the light-transmitting sheet change due to temperature, boundary fixation, and surface contamination distribution. Fixed driving parameters cannot adapt to changes in operating conditions, resulting in uneven distribution of sound field energy on the surface of the light-transmitting sheet. Excessive vibration in some areas may cause fatigue damage to the light-transmitting sheet, while insufficient vibration in other areas creates cleaning blind spots. Moreover, existing methods lack the ability to perceive the actual vibration state of the light-transmitting sheet surface in real time, and cannot obtain spatial information of the sound field distribution during the cleaning process. Summary of the Invention

[0004] In the prior art, fixed or simple frequency sweep drive cannot adapt to changes in the acoustic characteristics of the light-transmitting film, resulting in uneven distribution of sound field energy, cleaning blind spots or excessive local vibrations, lack of spatial perception of the actual vibration state of the light-transmitting film surface, and inability to monitor the sound field distribution. In view of the shortcomings of the prior art, the present invention provides a vibration control system for ultrasonic cleaning of camera lenses.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a vibration control system for ultrasonic cleaning of camera lenses, specifically comprising:

[0006] Data acquisition module: acquires electrical response signals collected by several intelligent piezoelectric sensor transducers arranged on the edge of the lens during frequency sweep excitation. The electrical response signals include voltage amplitude signals and current phase signals at both ends of each intelligent piezoelectric sensor transducer.

[0007] Sound field distribution construction module: Based on the electrical response signal, the transient sound field distribution description data of the lens lens during the current cleaning cycle is constructed through the signal conditioning unit built into the intelligent piezoelectric sensor transducer. The transient sound field distribution description data is used to characterize the vibration amplitude distribution and vibration phase distribution at each spatial position on the surface of the lens lens.

[0008] Node identification module: Based on the transient sound field distribution description data, it identifies the unwanted sound field gathering node regions appearing on the surface of the light-transmitting sheet, and determines the spatial location and vibration energy concentration of the unwanted sound field gathering node regions;

[0009] Phase compensation module: Based on the spatial location and vibration energy concentration of the identified unwanted sound field gathering node area, an inverse phase compensation drive signal is generated and superimposed on the drive signal of the corresponding intelligent piezoelectric sensor transducer to reduce the vibration amplitude of the unwanted sound field gathering node area.

[0010] Parameter adjustment module: After the cleaning cycle ends, the cleaning uniformity is evaluated based on the transient sound field distribution description data. When the cleaning uniformity does not meet expectations, the starting frequency and sweep step size of the sweep excitation in the next cleaning cycle are adjusted.

[0011] Preferably, the data acquisition module has a first intelligent piezoelectric sensor transducer, a second intelligent piezoelectric sensor transducer, a third intelligent piezoelectric sensor transducer and a fourth intelligent piezoelectric sensor transducer arranged at equal intervals along the circumferential direction on the edge of the lens light-transmitting sheet, and the central angle interval between adjacent intelligent piezoelectric sensor transducers is a right angle.

[0012] A sweep frequency drive signal is generated by a sweep frequency controller. The sweep frequency drive signal changes the frequency sequentially in the first frequency range to the second frequency range with a preset sweep frequency step size. The lower limit of the first frequency range is located near the series resonant frequency of the intelligent piezoelectric sensor transducer, and the upper limit of the second frequency range is located near the parallel resonant frequency of the intelligent piezoelectric sensor transducer.

[0013] At each frequency sweep point, the frequency sweep drive signal is amplified and simultaneously applied to four intelligent piezoelectric sensor transducers. After continuous excitation until steady-state vibration, the voltage amplitude signal at both ends of the transducer is collected through the built-in voltage detection circuit of each intelligent piezoelectric sensor transducer, and the phase difference signal between the drive current and the voltage at both ends of the transducer is collected through the built-in phase comparison circuit of each intelligent piezoelectric sensor transducer.

[0014] The voltage amplitude and phase difference signals of the first, second, third, and fourth intelligent piezoelectric transducers at the same sweep frequency point are grouped into one data group. All data groups are arranged in ascending order of sweep frequency point to form an electrical response signal.

[0015] Preferably, for each frequency sweep point, the sound field distribution construction module acquires the voltage amplitude signal and phase difference signal of the first intelligent piezoelectric sensor transducer, the second intelligent piezoelectric sensor transducer, the third intelligent piezoelectric sensor transducer, and the fourth intelligent piezoelectric sensor transducer at that frequency sweep point.

[0016] Divide the voltage amplitude signal of each intelligent piezoelectric sensor transducer by the electrode spacing of the transducer to obtain the electric field strength value. Multiply the electric field strength value by the piezoelectric strain constant to obtain the mechanical strain amplitude. Multiply the mechanical strain amplitude by the stiffness coefficient of the contact surface between the transducer and the light-transmitting sheet to obtain the vibration excitation intensity at the installation position of the corresponding intelligent piezoelectric sensor transducer.

[0017] The phase difference signal of each intelligent piezoelectric sensor transducer is demodulated to obtain the phase difference between the driving current and the terminal voltage. The vibration phase at the corresponding installation position is calculated based on the phase relationship between the branch current and the mechanical vibration component in the equivalent circuit model of the transducer.

[0018] Using the surface of the transparent sheet as a planar coordinate system, and taking the installation coordinates of each intelligent piezoelectric sensor transducer as the excitation point, the phase delay and amplitude attenuation coefficient of the wave emitted from each excitation point propagating to the grid point are calculated for each discrete grid point on the surface of the transparent sheet. The phase delay is obtained by dividing the distance between the excitation point and the grid point by the phase velocity of the wave at that frequency and then multiplying by the angular frequency. The amplitude attenuation coefficient is determined by the propagation distance and the damping characteristics of the material.

[0019] The vibration phase at each excitation point is obtained by subtracting the corresponding phase delay from the vibration phase at each excitation point. The vibration amplitude at each excitation point is obtained by multiplying the vibration excitation intensity at each excitation point by the corresponding amplitude attenuation coefficient.

[0020] The vibration components generated at the same grid point by each excitation point are vector superimposed using phasor addition. The magnitude of the composite vector is taken as the superimposed vibration amplitude, and the phase angle of the composite vector is taken as the superimposed vibration phase.

[0021] The vibration amplitude and phase of each discrete grid point are superimposed and arranged according to the grid row and column positions to form the transient sound field distribution description data corresponding to the frequency sweep points.

[0022] Preferably, in the transient sound field distribution description data, the node identification module traverses each discrete grid point on the surface of the light-transmitting sheet. For each grid point, it obtains the superimposed vibration amplitude value of the grid point and the superimposed vibration amplitude values ​​of all adjacent grid points directly adjacent to the grid point in the row or column direction. It calculates the arithmetic mean of the superimposed vibration amplitude values ​​of the adjacent grid points as the neighborhood average amplitude. It divides the absolute value of the difference between the superimposed vibration amplitude value of the grid point and the neighborhood average amplitude by the neighborhood average amplitude to obtain the amplitude deviation ratio.

[0023] When the amplitude deviation ratio of a certain grid point exceeds the first amplitude deviation reference value, and the superimposed vibration amplitude of all grid points in the connected region formed by searching for adjacent grid points with the grid point as the seed point and continuously expanding to satisfy the superimposed vibration amplitude being greater than the first amplitude reference value is greater than the first amplitude reference value, the connected region is identified as a non-desired sound field gathering node region.

[0024] The geometric center row coordinates are obtained by summing the row coordinates of all grid points within the region of the unwanted sound field gathering node and dividing the sum by the total number of grid points. The geometric center column coordinates are obtained by summing the column coordinates of all grid points and dividing the sum by the total number of grid points. The geometric center row coordinates and geometric center column coordinates are used as the spatial location of the region of the unwanted sound field gathering node.

[0025] The arithmetic mean of the sum of the superimposed vibration amplitude values ​​of all grid points in the unwanted sound field clustering node region and divided by the total number of grid points is used as the degree of vibration energy concentration in the unwanted sound field clustering node region.

[0026] Preferably, for each identified unwanted sound field clustering node region, the phase compensation module obtains the superimposed vibration phase value at the geometric center coordinates of the unwanted sound field clustering node region from the transient sound field distribution description data;

[0027] Based on the superimposed vibration phase value, add 180 degrees to the superimposed vibration phase value to obtain the inverse phase target value. When the sum exceeds 360 degrees, subtract 360 degrees to return to the range of 0 to 360 degrees. The inverse phase target value and the superimposed vibration phase value differ by half a vibration cycle.

[0028] An initial additional phase offset and an initial additional amplitude adjustment are set for the first, second, third, and fourth intelligent piezoelectric sensor transducers, respectively. The propagation phase delay is calculated based on the distance from the installation position of each intelligent piezoelectric sensor transducer to the geometric center coordinates. The original vibration phase of the main drive signal of each intelligent piezoelectric sensor transducer is added to the additional phase offset and then the propagation phase delay is subtracted to obtain the vibration phase of each additional sound wave at the geometric center. The vibration phases of each additional sound wave are then synthesized by phasor to obtain the additional synthesized vibration prediction phase.

[0029] Adjust the additional phase offset of each intelligent piezoelectric sensor transducer until the deviation between the additional synthetic vibration prediction phase and the target value of the inverse phase is less than the allowable value of the phase deviation. Adjust the additional amplitude adjustment of each intelligent piezoelectric sensor transducer until the ratio between the additional synthetic vibration prediction amplitude and the original superimposed vibration amplitude at the geometric center is within the amplitude matching range.

[0030] The adjusted additional phase offset and additional amplitude adjustment are converted into a sinusoidal AC voltage signal with the same frequency as the main drive signal as the inverse phase compensation drive signal. The amplitude of the inverse phase compensation drive signal is the amplitude of the main drive signal multiplied by the additional amplitude adjustment, and the phase of the inverse phase compensation drive signal is the phase of the main drive signal plus the additional phase offset. The inverse phase compensation drive signal is superimposed on the main drive signal and applied to the corresponding intelligent piezoelectric sensor transducer.

[0031] Preferably, after the cleaning cycle is completed, the parameter adjustment module controls the first, second, third, and fourth intelligent piezoelectric sensor transducers to switch to the sensing working mode so that the sweep frequency signal of the detection power level is applied to each intelligent piezoelectric sensor transducer in sequence, and the sweep frequency range and sweep frequency step size are consistent with the cleaning excitation stage.

[0032] At each frequency sweep point, the voltage amplitude signal is obtained through the built-in voltage detection circuit of each intelligent piezoelectric sensor transducer, and the phase difference signal between the driving current and the voltage across the transducer is obtained through the phase comparison circuit to form the electrical response signal after cleaning.

[0033] Based on the electrical response signal after cleaning, the voltage amplitude signal is converted into the vibration excitation intensity at the installation position of each intelligent piezoelectric sensor transducer, and the phase difference signal is converted into the vibration phase. Using the surface of the light-transmitting sheet as a plane coordinate system, the superimposed vibration amplitude and superimposed vibration phase at each discrete grid point are calculated by wave field superposition method to form the transient sound field distribution description data after cleaning.

[0034] Traverse all discrete grid points in the transient sound field distribution description data after cleaning, compare the superimposed vibration amplitude value of each grid point with the lower limit of the expected vibration amplitude range, and mark the grid points whose superimposed vibration amplitude value is less than the lower limit as grid points not covered by cleaning.

[0035] The total number of uncovered grid points is counted, and the percentage of missing clean coverage is obtained by dividing the total number of all discrete grid points on the surface of the light-transmitting sheet by the total number of uncovered grid points.

[0036] When the proportion of missing cleaning coverage is greater than the first reference value for missing coverage, the cleaning uniformity is determined to be unsatisfactory.

[0037] Analyze the spatial distribution of uncovered grid points on the surface of the light-transmitting sheet. When the uncovered grid points are concentrated in the edge area of ​​the light-transmitting sheet, adjust the starting frequency of the next cleaning cycle to a lower frequency. When the uncovered grid points are concentrated in the center area of ​​the light-transmitting sheet, adjust the starting frequency of the next cleaning cycle to a higher frequency or expand the upper limit of the frequency range. When the uncovered grid points are distributed in a discrete spot-like pattern, reduce the frequency sweep step size of the next cleaning cycle.

[0038] This invention provides a vibration control system for ultrasonic cleaning of camera lenses, which has the following beneficial effects:

[0039] This invention deploys several intelligent piezoelectric sensing transducers along the edge of the lens's light-transmitting film, excites and synchronously acquires the voltage amplitude signal and current phase signal of each transducer in a frequency sweep manner, and the intelligent piezoelectric sensing transducers sense the transducer's own electrical response while exciting the light-transmitting film to generate ultrasonic vibration, thus obtaining the original data for sound field reconstruction without the need for additional independent sensors.

[0040] Based on transient sound field distribution description data, unwanted sound field aggregation node regions are identified. By using both amplitude deviation ratio and absolute amplitude as dual conditions, regions with abnormal energy concentration are determined, and their spatial location and energy concentration degree are extracted. For each aggregation node, the target value of the reverse phase is determined based on the superimposed vibration phase at the geometric center. The additional phase offset and amplitude adjustment required for each transducer are calculated, and a reverse phase compensation drive signal is generated and superimposed on the main drive signal. The reverse phase compensation selectively suppresses areas with excessive local energy without affecting the overall cleaning ability, effectively improving the uniformity of the sound field and reducing the risk of local fatigue damage to the light-transmitting sheet. Attached Figure Description

[0041] Figure 1 This is a system block diagram of the present invention. Detailed Implementation

[0042] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] Please see Figure 1 This invention provides a vibration control system for ultrasonic cleaning of camera lenses, comprising:

[0044] Data acquisition module: acquires electrical response signals collected by several intelligent piezoelectric sensor transducers arranged on the edge of the lens during frequency sweep excitation. The electrical response signals include voltage amplitude signals and current phase signals at both ends of each intelligent piezoelectric sensor transducer.

[0045] In this embodiment of the invention, the data acquisition module needs to be specifically described. The data acquisition module has a first intelligent piezoelectric sensor transducer, a second intelligent piezoelectric sensor transducer, a third intelligent piezoelectric sensor transducer, and a fourth intelligent piezoelectric sensor transducer arranged at equal intervals along the circumferential direction on the edge of the lens light-transmitting sheet. The central angle interval between adjacent intelligent piezoelectric sensor transducers is a right angle.

[0046] A sweep frequency drive signal is generated by a sweep frequency controller. The sweep frequency drive signal changes the frequency sequentially in the first frequency range to the second frequency range with a preset sweep frequency step size. The lower limit of the first frequency range is located near the series resonant frequency of the intelligent piezoelectric sensor transducer, and the upper limit of the second frequency range is located near the parallel resonant frequency of the intelligent piezoelectric sensor transducer.

[0047] At each frequency sweep point, the frequency sweep drive signal is amplified and simultaneously applied to four intelligent piezoelectric sensor transducers. After continuous excitation until steady-state vibration, the voltage amplitude signal at both ends of the transducer is collected through the built-in voltage detection circuit of each intelligent piezoelectric sensor transducer, and the phase difference signal between the drive current and the voltage at both ends of the transducer is collected through the built-in phase comparison circuit of each intelligent piezoelectric sensor transducer.

[0048] The voltage amplitude and phase difference signals of the first, second, third, and fourth intelligent piezoelectric transducers at the same sweep frequency point are grouped into one data group. All data groups are arranged in ascending order of sweep frequency point to form an electrical response signal.

[0049] It should be noted that the lens lens is a transparent flat plate at the front of the camera lens used to protect the internal optical lens group. The principle of ultrasonic cleaning is to convert high-frequency electrical signals into mechanical vibrations through a piezoelectric transducer. The vibration energy propagates along the surface of the lens in the form of elastic waves, causing the contaminants attached to the surface to be peeled off or atomized and removed under the action of inertial force. The intelligent piezoelectric sensor transducer is a piezoelectric device. When its internal piezoelectric ceramic element is subjected to an alternating electric field, it will produce mechanical deformation, thereby exciting the lens to produce ultrasonic vibrations.

[0050] When subjected to mechanical stress, piezoelectric ceramic elements also generate charge output at both ends of the electrodes. The coexistence of inverse piezoelectric effect and direct piezoelectric effect allows the same device to be used as both a vibration excitation source and a vibration state sensor.

[0051] The first, second, third, and fourth intelligent piezoelectric transducers, which are equally spaced along the circumferential edge of the lens aperture, output drive signals in a frequency sweep manner within the first to second frequency range.

[0052] The circumferentially spaced arrangement refers to the uniform distribution of four intelligent piezoelectric transducers on the circumferential edge of the light-transmitting sheet, with the central angle between adjacent transducers being a right angle. This symmetrical arrangement can generate a sound field distribution with good spatial uniformity on the surface of the light-transmitting sheet.

[0053] The first and second frequency ranges define the frequency range of the sweep excitation. The lower limit of the first frequency range is usually located near the series resonant frequency of the piezoelectric transducer, and the upper limit of the second frequency range is usually located near the parallel resonant frequency. This frequency range covers the main acoustic resonant modes of the transparent sheet structure. The sweep excitation gradually changes the driving signal frequency according to a fixed frequency step size, thereby exciting the vibration response of the transparent sheet at different frequencies in sequence.

[0054] At each frequency sweep point, the voltage amplitude signal is obtained through the voltage detection circuit built into each intelligent piezoelectric sensor transducer, and the phase difference signal between the driving current and the voltage across the transducer is obtained through the phase comparison circuit built into the intelligent piezoelectric sensor transducer.

[0055] The built-in voltage detection circuit of the intelligent piezoelectric sensing transducer refers to the voltage sampling unit integrated in the transducer drive and sensing conditioning circuit. The voltage sampling unit extracts a sampling signal proportional to the voltage amplitude from the AC high voltage signal at both ends of the transducer through resistor voltage division or capacitor voltage division. After rectification and filtering, it is converted into a DC level or digital quantity representing the voltage amplitude.

[0056] The voltage amplitude signal reflects the magnitude of the electric field strength applied to the piezoelectric transducer at the swept frequency point. The greater the electric field strength, the greater the mechanical strain generated by the transducer and the stronger the excitation on the light-transmitting sheet. The phase comparison circuit built into the intelligent piezoelectric sensing transducer refers to the phase detection unit integrated in the conditioning circuit. The phase detection unit simultaneously receives the drive current signal flowing through the transducer and the voltage signal across the transducer. It measures the phase difference between two AC signals of the same frequency through zero-crossing detection or multiplication phase detection.

[0057] The phase difference between the driving current and the voltage across the transducer reflects the impedance characteristics of the piezoelectric transducer at the excitation frequency. When the excitation frequency is equal to the mechanical resonant frequency of the piezoelectric transducer, the driving current and the terminal voltage are in phase and the phase difference is close to zero. When the excitation frequency deviates from the resonant frequency, the transducer exhibits capacitive or inductive characteristics, and the phase difference is positive or negative. The phase difference signal contains the coupling information between the mechanical vibration state of the transducer and the electrical excitation, and is an important basis for judging whether the transducer is working in the optimal resonant state and the vibration phase distribution on the surface of the light-transmitting sheet.

[0058] Each intelligent piezoelectric transducer synchronously performs voltage amplitude and phase difference acquisition at each sweep frequency point. The acquisition operation is controlled by a unified sweep controller triggering a synchronization signal to ensure that the data from the four transducers at the same frequency point are strictly corresponding in time. The sweep controller generates sinusoidal drive signals for each frequency point sequentially according to the preset sweep start frequency, sweep end frequency, and sweep step size. After power amplification, these signals are applied to the four intelligent piezoelectric transducers respectively. At each frequency point, after the drive signal continues for several cycles to reach a steady-state oscillation state, the voltage detection circuit and phase comparison circuit are triggered to perform a data acquisition, recording the voltage amplitude signal and phase difference signal corresponding to each of the four transducers at that frequency point.

[0059] After completing the acquisition of one frequency point, the sweep controller will increase the drive frequency by one sweep step size and enter the excitation and acquisition of the next frequency point until all frequency points in the first frequency range to the second frequency range are covered. The size of the sweep step size determines the density of frequency sampling. The smaller the step size, the more sweep points there are, and the more detailed the characterization of the frequency response characteristics of the light-transmitting sheet is. However, the sweep cycle is also extended accordingly. The selection of the step size needs to achieve a balance between frequency resolution and cleaning response time.

[0060] After completing the excitation and acquisition of all frequency sweep points, the voltage amplitude signal and phase difference signal of each intelligent piezoelectric transducer at each frequency sweep point are arranged in frequency order to form an electrical response signal. A two-dimensional data table is constructed with the frequency sweep point number as the first index dimension and the intelligent piezoelectric transducer number as the second index dimension. Each row of the data table corresponds to a frequency sweep point. Each row contains the voltage amplitude, phase difference value, voltage amplitude, phase difference value, voltage amplitude, phase difference value, voltage amplitude, phase difference value, and phase difference value of the first, second, third, and fourth intelligent piezoelectric transducers.

[0061] Arranged by frequency point order, this means that the rows of the data table are arranged in order of frequency points from low to high. The electrical response signal completely records the amplitude frequency response characteristics and phase frequency response characteristics of the electrical ports of each transducer when the light-transmitting sheet is jointly excited by four intelligent piezoelectric sensor transducers.

[0062] Sound field distribution construction module: Based on the electrical response signal, the transient sound field distribution description data of the lens lens during the current cleaning cycle is constructed through the signal conditioning unit built into the intelligent piezoelectric sensor transducer. The transient sound field distribution description data is used to characterize the vibration amplitude distribution and vibration phase distribution at each spatial position on the surface of the lens lens.

[0063] In this embodiment of the invention, the sound field distribution construction module needs to be specifically described. For each frequency sweep point, the sound field distribution construction module acquires the voltage amplitude signal and phase difference signal of the first intelligent piezoelectric sensor transducer, the second intelligent piezoelectric sensor transducer, the third intelligent piezoelectric sensor transducer, and the fourth intelligent piezoelectric sensor transducer at that frequency sweep point.

[0064] Divide the voltage amplitude signal of each intelligent piezoelectric sensor transducer by the electrode spacing of the transducer to obtain the electric field strength value. Multiply the electric field strength value by the piezoelectric strain constant to obtain the mechanical strain amplitude. Multiply the mechanical strain amplitude by the stiffness coefficient of the contact surface between the transducer and the light-transmitting sheet to obtain the vibration excitation intensity at the installation position of the corresponding intelligent piezoelectric sensor transducer.

[0065] The phase difference signal of each intelligent piezoelectric sensor transducer is demodulated to obtain the phase difference between the driving current and the terminal voltage. The vibration phase at the corresponding installation position is calculated based on the phase relationship between the branch current and the mechanical vibration component in the equivalent circuit model of the transducer.

[0066] Using the surface of the transparent sheet as a planar coordinate system, and taking the installation coordinates of each intelligent piezoelectric sensor transducer as the excitation point, the phase delay and amplitude attenuation coefficient of the wave emitted from each excitation point propagating to the grid point are calculated for each discrete grid point on the surface of the transparent sheet. The phase delay is obtained by dividing the distance between the excitation point and the grid point by the phase velocity of the wave at that frequency and then multiplying by the angular frequency. The amplitude attenuation coefficient is determined by the propagation distance and the damping characteristics of the material.

[0067] The vibration phase at each excitation point is obtained by subtracting the corresponding phase delay from the vibration phase at each excitation point. The vibration amplitude at each excitation point is obtained by multiplying the vibration excitation intensity at each excitation point by the corresponding amplitude attenuation coefficient.

[0068] The vibration components generated at the same grid point by each excitation point are vector superimposed using phasor addition. The magnitude of the composite vector is taken as the superimposed vibration amplitude, and the phase angle of the composite vector is taken as the superimposed vibration phase.

[0069] The vibration amplitude and phase of each discrete grid point are superimposed and arranged according to the grid row and column positions to form the transient sound field distribution description data corresponding to the frequency sweep point.

[0070] It should be noted that the signal conditioning unit built into the intelligent piezoelectric sensing transducer not only includes a voltage detection circuit and a phase comparison circuit, but also includes an embedded processing core for performing sound field reconstruction calculations. The embedded processing core receives the electrical response signals at each sweep frequency point, converts the electrical quantity into mechanical vibration quantity according to the electromechanical conversion characteristics of the piezoelectric transducer and the acoustic propagation characteristics of the light-transmitting sheet, and calculates the vibration state at any spatial position on the surface of the light-transmitting sheet.

[0071] Transient sound field distribution description data is used to characterize the vibration amplitude distribution and vibration phase distribution at various spatial locations on the surface of the light-transmitting sheet. The vibration amplitude distribution reflects the strength distribution of cleaning energy on the surface of the light-transmitting sheet. The larger the vibration amplitude, the stronger the stripping effect on pollutants.

[0072] The vibration phase distribution reflects the temporal relationship of vibrations at various points on the surface of the light-transmitting sheet. Regions with good phase consistency have high vibration coordination, while regions with chaotic phases may have sound field nodes where energy cancels each other out. The process of constructing transient sound field distribution description data is carried out point by point with frequency sweep as the unit.

[0073] For each sweep frequency point, firstly acquire the voltage amplitude signal and phase difference signal of each intelligent piezoelectric sensor transducer at that frequency point, convert the voltage amplitude signal into the vibration excitation intensity at the corresponding installation position of the intelligent piezoelectric sensor transducer, and convert the phase difference signal into the vibration phase at the corresponding installation position.

[0074] The conversion from voltage amplitude signal to vibration excitation intensity is based on the piezoelectric strain constant and electromechanical coupling coefficient of the intelligent piezoelectric sensor transducer. The piezoelectric strain constant describes the mechanical strain generated by the piezoelectric material when a unit electric field strength is applied, and the electromechanical coupling coefficient describes the conversion efficiency between electrical energy and mechanical energy.

[0075] The specific conversion method is as follows: divide the voltage amplitude signal by the transducer electrode spacing to obtain the electric field strength value, multiply the electric field strength value by the piezoelectric strain constant to obtain the mechanical strain amplitude, and then multiply the mechanical strain amplitude by the stiffness coefficient of the contact surface between the transducer and the light-transmitting sheet to obtain the vibration excitation intensity of the transducer acting on the edge of the light-transmitting sheet. The vibration excitation intensity is the mechanical force amplitude or displacement amplitude applied by the transducer to the light-transmitting sheet at the installation position.

[0076] The conversion of phase difference signal to vibration phase is based on the phase frequency characteristics of piezoelectric transducer near the resonant frequency: when the excitation frequency is lower than the series resonant frequency, the mechanical vibration phase of the transducer lags behind the driving voltage phase; when the excitation frequency is equal to the series resonant frequency, the vibration phase is basically in phase with the driving voltage phase; when the excitation frequency is higher than the series resonant frequency, the vibration phase leads the driving voltage phase.

[0077] The phase difference signal is demodulated to obtain the phase difference between the driving current and the terminal voltage. Then, based on the phase relationship between the current of each branch and the mechanical vibration component in the equivalent circuit model of the transducer, the vibration phase of the mechanical vibration of the transducer relative to the driving voltage reference is calculated. The vibration excitation intensity and vibration phase corresponding to the first intelligent piezoelectric sensing transducer are recorded as the first excitation point parameter, and the second intelligent piezoelectric sensing transducer corresponds to the second excitation point parameter.

[0078] After obtaining the vibration excitation intensity and vibration phase of the four excitation points, the installation position of each intelligent piezoelectric sensor transducer is taken as the known excitation point, with the surface of the transparent sheet as the plane coordinate system. Based on the vibration excitation intensity and vibration phase of each excitation point, the superimposed vibration amplitude and superimposed vibration phase at each discrete grid point on the surface of the transparent sheet are calculated by wave field superposition.

[0079] Using the surface of the light-transmitting sheet as a plane coordinate system means establishing a two-dimensional rectangular coordinate system with the geometric center of the light-transmitting sheet as the origin and the plane where the light-transmitting sheet is located as the reference plane. The installation positions of the four intelligent piezoelectric sensor transducers are projected onto this coordinate system to obtain their respective coordinate values.

[0080] The surface of the light-transmitting sheet is divided into several discrete grid points according to a preset spatial resolution. The grid points are equally spaced in the two coordinate axes, forming a regular grid covering the entire surface of the light-transmitting sheet. The mechanical vibration generated by each excitation point propagates in the form of a bending wave or a longitudinal wave along the surface of the light-transmitting sheet. During the propagation process, the amplitude of the wave decreases as the propagation distance increases, and the phase of the wave is delayed as the propagation distance increases.

[0081] For each discrete grid point on the surface of the light-transmitting sheet, the vibration contribution of the waves emitted from the four excitation points when they reach that grid point is calculated. The calculation method is as follows: For the first excitation point, the straight-line distance between it and the grid point is calculated. The distance is divided by the phase velocity of the wave propagating along the light-transmitting sheet at that frequency to obtain the propagation time delay. The propagation time delay is multiplied by the angular frequency to obtain the phase delay. The vibration phase of the first excitation point is subtracted from the phase delay to obtain the vibration phase generated by the first excitation point at that grid point. The vibration excitation intensity of the first excitation point is multiplied by the amplitude attenuation coefficient, which is determined according to the propagation distance and the damping characteristics of the material, to obtain the vibration amplitude generated by the first excitation point at that grid point. The vibration amplitude and vibration phase of the second, third, and fourth excitation points at the grid point are calculated in the same way. The vibration generated by the four excitation points at the same grid point is represented as four sinusoidal vibration components with their own amplitude and phase. The four components are vector superimposed using phasor addition: each component is decomposed into in-phase components and orthogonal components. After accumulating them, the magnitude of the composite vector is obtained as the superimposed vibration amplitude. The phase angle of the composite vector is obtained as the superimposed vibration phase. The above calculations are performed on all discrete grid points on the surface of the light-transmitting sheet one by one to obtain the superimposed vibration amplitude and superimposed vibration phase at each grid point.

[0082] After calculating the superimposed vibration amplitude and superimposed vibration phase of all discrete grid points, the superimposed vibration amplitude and superimposed vibration phase of each discrete grid point are arranged according to the grid spatial position to form transient sound field distribution description data corresponding to the sweep frequency point. Arranging according to the grid spatial position means establishing a two-dimensional data array with the same number of rows and columns as the discrete grid. The element in the i-th row and j-th column of the array corresponds to the sound field state at the i-th row and j-th column grid point on the surface of the transparent sheet. Each element contains two values: the first value is the superimposed vibration amplitude of the grid point, and the second value is the superimposed vibration phase of the grid point.

[0083] The transient sound field distribution description data corresponding to the frequency sweep point is stored in the storage area of ​​the built-in signal conditioning unit of the intelligent piezoelectric sensor transducer in the form of a two-dimensional array. For each frequency point in the frequency sweep process, its corresponding transient sound field distribution description data is constructed to form a set of sound field distribution sequences that vary with frequency.

[0084] When it is necessary to obtain the sound field distribution at a specific moment within the current cleaning cycle, the transient sound field distribution description data at the corresponding frequency point can be retrieved according to the timing relationship of the frequency sweep excitation. The transient sound field distribution description data describes the vibration intensity and vibration timing at each spatial position on the surface of the light-transmitting sheet under the current excitation configuration, providing spatially refined sound field information for identifying sound field aggregation node regions, generating inverse phase compensation signals, and evaluating cleaning uniformity.

[0085] It should be noted that the specific steps for obtaining the vibration phase of the transducer's mechanical vibration relative to the driving voltage reference are as follows:

[0086] The phase comparison circuit built into the intelligent piezoelectric sensor transducer outputs a phase difference signal, which is an analog voltage or a digital quantity. The phase comparison circuit simultaneously receives the drive current signal flowing through the transducer and the terminal voltage signal at both ends of the transducer. Both are sine waves of the same frequency. The phase comparison circuit first sends the two signals to the zero-crossing detection unit. The zero-crossing detection unit identifies the moment when each signal crosses the zero level from negative to positive and outputs the corresponding zero-crossing pulse.

[0087] There is a time interval between the zero-crossing pulse generation time of the drive current signal and the zero-crossing pulse generation time of the terminal voltage signal. The phase comparison circuit is equipped with a high-frequency counting clock. The counting clock frequency is much higher than the drive signal frequency. The number of high-frequency counting clock pulses is counted during the time interval between the zero-crossing pulse of the drive current and the zero-crossing pulse of the terminal voltage. The count value reflects the length of the time interval. The time delay is obtained by multiplying the count value by the counting clock period.

[0088] The phase comparison circuit measures the period length of the drive signal. It counts the time interval between two consecutive zero-crossing pulses of the same signal in the same direction and converts it into the signal period length. The signal period length corresponds to a phase angle of 360 degrees for the complete period. Dividing the time delay by the signal period length and then multiplying by 360 degrees gives the phase angle value of the drive current signal lagging behind the terminal voltage signal. If the zero-crossing pulse of the drive current is later than the zero-crossing pulse of the terminal voltage, the phase difference is recorded as a negative value, indicating that the current lags behind the voltage. If the zero-crossing pulse of the drive current is earlier than the zero-crossing pulse of the terminal voltage, the phase difference is recorded as a positive value, indicating that the current leads the voltage. This phase angle value is the phase difference between the drive current and the terminal voltage.

[0089] The coupling relationship between the electrical port characteristics and mechanical vibration characteristics of a piezoelectric transducer can be characterized by a lumped parameter equivalent circuit model near the operating frequency. The equivalent circuit model consists of two parallel branches. The first branch is a static capacitor branch, which contains only one capacitor element, representing the inherent dielectric capacitance between the transducer electrodes. The current component flowing through this branch is called the static branch current. The phase of the static branch current always leads the phase of the front-end voltage by ninety degrees.

[0090] The second branch is the dynamic branch, which consists of a series of resistive, inductive, and capacitive elements. It represents the equivalent mapping of the transducer's mechanical vibration system at the electrical end. The resistive element corresponds to mechanical damping, the inductive element corresponds to equivalent mass, and the capacitive element corresponds to equivalent stiffness. The current component in the dynamic branch is called the dynamic branch current. The dynamic branch current is proportional to the mechanical vibration velocity of the transducer. Therefore, the phase of the dynamic branch current represents the phase of the mechanical vibration velocity. The total driving current flowing through the transducer terminals is the phasor sum of the static branch current and the dynamic branch current.

[0091] The known terminal voltage phase can be defined as the reference zero phase. The static branch current phase is fixed at 90 degrees to the front-end voltage phase. The static branch current amplitude is equal to the terminal voltage amplitude divided by the capacitive reactance of the static capacitor at the excitation frequency. The magnitude of the capacitive reactance is inversely proportional to the excitation frequency and the static capacitance value. Given the excitation frequency and the static capacitance value, the static branch current amplitude can be calculated. The total drive current amplitude is obtained by actual measurement through the current sampling circuit. The phase difference between the total drive current and the terminal voltage has been obtained by phase demodulation.

[0092] The total drive current is represented as a phasor with a known amplitude and a known phase difference, and the static branch current is represented as a phasor with a known amplitude and a fixed phase relationship. The total drive current phasor is equal to the vector sum of the static branch current phasor and the dynamic branch current phasor. The dynamic branch current phasor is equal to the total drive current phasor minus the static branch current phasor. The specific execution method of the phasor subtraction operation is as follows: the total drive current phasor is decomposed into a component along the zero-phase reference direction and a component perpendicular to it. The static branch current phasor is also decomposed into components in two directions. Since the phase of the static branch current is fixed to lead by 90 degrees, its component along the zero-phase reference direction is zero, and its component perpendicular to it is positive. The components of the two phasors in the same direction are subtracted to obtain the component values ​​of the dynamic branch current phasor in the two directions. The phase angle of the dynamic branch current phasor is calculated from these two component values. The calculation method is to take the arctangent of the ratio of the vertical component to the horizontal component, and determine the quadrant of the phase angle according to the positive and negative signs of the two components. The obtained phase angle is the phase of the dynamic branch current relative to the terminal voltage reference. There is a linear proportional relationship between the dynamic branch current and the mechanical vibration velocity of the transducer, and the two are in perfect phase. Therefore, the phase of the dynamic branch current relative to the terminal voltage is the same as the phase of the mechanical vibration velocity of the transducer relative to the driving voltage.

[0093] Under steady-state simple harmonic vibration conditions, the vibration displacement phase lags behind the vibration velocity phase by 90 degrees. If the vibration displacement is to be used as the vibration phase characterization quantity, then the phase of the dynamic branch current is subtracted by 90 degrees. The result is the vibration phase of the transducer's mechanical vibration displacement relative to the driving voltage reference. If the vibration velocity is used as the vibration phase characterization quantity, then the phase of the dynamic branch current is directly used as the vibration phase.

[0094] Node identification module: Based on the transient sound field distribution description data, it identifies the unwanted sound field gathering node regions appearing on the surface of the light-transmitting sheet, and determines the spatial location and vibration energy concentration of the unwanted sound field gathering node regions;

[0095] In this embodiment of the invention, the node identification module needs to be specifically described. In the transient sound field distribution description data, the node identification module traverses each discrete grid point on the surface of the light-transmitting sheet. For each grid point, it obtains the superimposed vibration amplitude value of the grid point and the superimposed vibration amplitude values ​​of all adjacent grid points directly adjacent to the grid point in the row or column direction. It calculates the arithmetic mean of the superimposed vibration amplitude values ​​of adjacent grid points as the neighborhood average amplitude. It divides the absolute value of the difference between the superimposed vibration amplitude value of the grid point and the neighborhood average amplitude by the neighborhood average amplitude to obtain the amplitude deviation ratio.

[0096] When the amplitude deviation ratio of a certain grid point exceeds the first amplitude deviation reference value, and the superimposed vibration amplitude of all grid points in the connected region formed by searching for adjacent grid points with the grid point as the seed point and continuously expanding to satisfy the superimposed vibration amplitude being greater than the first amplitude reference value is greater than the first amplitude reference value, the connected region is identified as a non-desired sound field gathering node region.

[0097] The geometric center row coordinates are obtained by summing the row coordinates of all grid points within the region of the unwanted sound field gathering node and dividing the sum by the total number of grid points. The geometric center column coordinates are obtained by summing the column coordinates of all grid points and dividing the sum by the total number of grid points. The geometric center row coordinates and geometric center column coordinates are used as the spatial location of the region of the unwanted sound field gathering node.

[0098] The arithmetic mean of the sum of the superimposed vibration amplitude values ​​of all grid points in the unwanted sound field clustering node region and divided by the total number of grid points is used as the degree of vibration energy concentration in the unwanted sound field clustering node region.

[0099] It should be noted that during ultrasonic cleaning, the ideal sound field distribution should be that the vibration amplitude is relatively uniform across the surface of the transparent sheet, so that contaminants attached to different locations can be subjected to sufficient vibration peeling force. Due to factors such as the fixed conditions of the transparent sheet boundary, the symmetry deviation of the piezoelectric transducer placement, and the matching relationship between the excitation frequency and the intrinsic mode of the transparent sheet, there are often local vibration amplitudes that are significantly higher than those of the surrounding areas in the actual sound field. Although the vibration energy is concentrated in these node areas, it will attract contaminants to migrate to the node areas and accumulate there, while weakening the vibration energy in other areas, resulting in a decrease in cleaning uniformity.

[0100] The first step in identifying the unwanted sound field clustering node region is to traverse each discrete grid point on the surface of the transparent sheet in the transient sound field distribution description data and calculate the amplitude deviation ratio between the superimposed vibration amplitude at each grid point and the average superimposed vibration amplitude of the adjacent grid points. The transient sound field distribution description data is stored in the form of a two-dimensional array. Each element of the array corresponds to a discrete grid point on the surface of the transparent sheet and contains two values: the superimposed vibration amplitude and the superimposed vibration phase of the discrete grid point. The traversal operation starts from the first row and first column of the array and visits each grid point in sequence according to the order of column first and then row or row first and then column.

[0101] For the currently accessed target grid point, determine the range of its adjacent grid points. Adjacent grid points refer to grid points that are directly adjacent to the target grid point in the row or column direction. They usually include four directly adjacent grid points: top, bottom, left, and right. For grid points located at the edge or corner of the light-transmitting sheet, the number of their adjacent grid points is reduced accordingly.

[0102] Extract the superimposed vibration amplitude value of the target grid point, and simultaneously extract the superimposed vibration amplitude values ​​of all adjacent grid points. Sum the superimposed vibration amplitude values ​​of the adjacent grid points and divide by the number of adjacent grid points to obtain the average superimposed vibration amplitude of the adjacent grid points. Calculate the amplitude deviation ratio between the superimposed vibration amplitude of the target grid point and this average value. The calculation method is as follows: subtract the average superimposed vibration amplitude of the adjacent grid points from the superimposed vibration amplitude of the target grid point, take the absolute value of the difference, and then divide this absolute value by the average superimposed vibration amplitude of the adjacent grid points. The amplitude deviation ratio reflects the degree of prominence of the vibration amplitude of the target grid point relative to the average level of its local neighborhood. The larger the deviation ratio, the more significantly the vibration energy at the target grid point is higher than that of the surrounding area, and the more likely it is to become a sound field accumulation node.

[0103] After calculating the amplitude deviation ratio of all discrete grid points, the region of undesirable sound field accumulation node is determined based on the two conditions of amplitude deviation ratio and absolute vibration amplitude. When the amplitude deviation ratio of a certain grid point exceeds the first amplitude deviation reference value, and the superimposed vibration amplitude of all grid points in the continuous region formed by the grid point and its spatially adjacent grid points is greater than the first amplitude reference value, the continuous region is identified as an undesirable sound field accumulation node region.

[0104] The first amplitude deviation reference value is a pre-set ratio threshold value. Its value is determined based on the acoustic properties of the light-transmitting sheet material and the requirements of the cleaning process for the uniformity of the sound field. It is used to distinguish between normal sound field fluctuations and abnormal energy accumulation. When the amplitude deviation ratio exceeds the first amplitude deviation reference value, it indicates that the vibration energy of the target grid point has significantly exceeded the background level of its neighborhood and has the potential to become the core of the accumulation node.

[0105] It is also necessary to ensure that the superimposed vibration amplitude of all grid points within the continuous area formed by the grid point and its spatially adjacent grid points is greater than the first amplitude reference value. The first amplitude reference value is a pre-set absolute vibration amplitude threshold value, which is determined by the minimum vibration amplitude required for effective cleaning and the maximum allowable vibration amplitude to avoid damage to the light-transmitting sheet. This condition is set to exclude the occasional high deviation ratio due to the overall low vibration amplitude of the local area, and to ensure that the identified clustering node area has sufficient vibration energy concentration. The continuous area is formed as follows: taking the target grid point that exceeds the first amplitude deviation reference value as the seed point, searching for adjacent grid points that also satisfy the condition of superimposed vibration amplitude being greater than the first amplitude reference value, including the adjacent grid points that meet the condition into the area, and continuing to search outward with the newly included grid points until all connected grid points that meet the condition are included. The connected area is the identified non-desired sound field clustering node area.

[0106] After identifying the unwanted sound field clustering node region, the geometric center coordinates of the unwanted sound field clustering node region are extracted as its spatial location. The average value of the superimposed vibration amplitude of all grid points in the unwanted sound field clustering node region is extracted as the degree of vibration energy concentration. The unwanted sound field clustering node region is composed of multiple adjacent discrete grid points. Each grid point has row coordinates and column coordinates in the light-transmitting plate plane coordinate system. The geometric center coordinates are extracted by: traversing all grid points contained in the region, accumulating the row coordinate values ​​and column coordinate values ​​of each grid point, dividing the accumulated row coordinate value by the total number of grid points in the region to obtain the geometric center row coordinates, and dividing the accumulated column coordinate value by the total number of grid points in the region to obtain the geometric center column coordinates.

[0107] The geometric center coordinates represent the spatial position of the unwanted sound field gathering node region on the surface of the transparent sheet. Traverse all the grid points contained in the unwanted sound field gathering node region, extract the superimposed vibration amplitude value of each grid point, sum all the superimposed vibration amplitude values, and then divide by the total number of grid points in the region to obtain the arithmetic mean of the superimposed vibration amplitude in the region.

[0108] The degree of vibration energy concentration reflects the absolute strength of vibration energy in the unwanted sound field gathering node region. The larger the average value, the more significant the energy concentration in the node region, and the greater the compensation intensity required to generate the reverse phase compensation signal. The spatial coordinates and vibration energy concentration of all the identified unwanted sound field gathering node regions are recorded one by one to form a node region description set, which provides input parameters for subsequent generation of reverse phase compensation drive signals node by node.

[0109] Phase compensation module: Based on the spatial location and vibration energy concentration of the identified unwanted sound field gathering node area, an inverse phase compensation drive signal is generated and superimposed on the drive signal of the corresponding intelligent piezoelectric sensor transducer to reduce the vibration amplitude of the unwanted sound field gathering node area.

[0110] In this embodiment of the invention, the phase compensation module is specifically described. For each identified unwanted sound field gathering node region, the phase compensation module obtains the superimposed vibration phase value at the geometric center coordinates of the unwanted sound field gathering node region from the transient sound field distribution description data.

[0111] Based on the superimposed vibration phase value, add 180 degrees to the superimposed vibration phase value to obtain the inverse phase target value. When the sum exceeds 360 degrees, subtract 360 degrees to return to the range of 0 to 360 degrees. The inverse phase target value and the superimposed vibration phase value differ by half a vibration cycle.

[0112] An initial additional phase offset and an initial additional amplitude adjustment are set for the first, second, third, and fourth intelligent piezoelectric sensor transducers, respectively. The propagation phase delay is calculated based on the distance from the installation position of each intelligent piezoelectric sensor transducer to the geometric center coordinates. The original vibration phase of the main drive signal of each intelligent piezoelectric sensor transducer is added to the additional phase offset and then the propagation phase delay is subtracted to obtain the vibration phase of each additional sound wave at the geometric center. The vibration phases of each additional sound wave are then synthesized by phasor to obtain the additional synthesized vibration prediction phase.

[0113] Adjust the additional phase offset of each intelligent piezoelectric sensor transducer until the deviation between the additional synthetic vibration prediction phase and the target value of the inverse phase is less than the allowable value of the phase deviation. Adjust the additional amplitude adjustment of each intelligent piezoelectric sensor transducer until the ratio between the additional synthetic vibration prediction amplitude and the original superimposed vibration amplitude at the geometric center is within the amplitude matching range.

[0114] The adjusted additional phase offset and additional amplitude adjustment are converted into a sinusoidal AC voltage signal with the same frequency as the main drive signal as the inverse phase compensation drive signal. The amplitude of the inverse phase compensation drive signal is the amplitude of the main drive signal multiplied by the additional amplitude adjustment, and the phase of the inverse phase compensation drive signal is the phase of the main drive signal plus the additional phase offset. The inverse phase compensation drive signal is superimposed on the main drive signal and applied to the corresponding intelligent piezoelectric sensor transducer.

[0115] It should be noted that when two vibrations with the same frequency and a phase difference of half a cycle meet at the same point in space, their vibration displacement directions are opposite and cancel each other out, thereby greatly reducing the combined vibration amplitude at that point. By controlling the phase and amplitude of the inverse phase compensation drive signal added to the drive signal of each intelligent piezoelectric sensor transducer, a reverse sound field can be generated only in the local area that needs to be suppressed without changing the original clean excitation main signal, thus achieving spatially selective vibration amplitude suppression.

[0116] For each identified unwanted sound field clustering node region, the superimposed vibration phase at the geometric center of the unwanted sound field clustering node region is first obtained. The coordinates of the geometric center have been obtained by averaging the coordinates of each grid point within the calculation area. The superimposed vibration phase refers to the phase value of the synthesized vibration generated by the joint excitation of the main drive signals of the four intelligent piezoelectric sensor transducers at the geometric center location. The superimposed vibration phase can be directly read from the transient sound field distribution description data. Specifically, based on the geometric center coordinates, the closest discrete grid point in the transient sound field distribution description data array is located, and the superimposed vibration phase value recorded at the discrete grid point is read.

[0117] If the coordinates of the geometric center do not fall on the discrete grid point, the interpolation result of the superimposed vibration phase of several surrounding grid points is taken as the superimposed vibration phase at the geometric center. The superimposed vibration phase reflects the time reference of the current vibration state of the node region. The goal of the reverse phase compensation is to make the vibration phase generated by the additional sound wave at this point form a time offset of half a cycle with the current superimposed vibration phase.

[0118] After obtaining the superimposed vibration phase at the geometric center of the unwanted sound field gathering node region, the target value of the inverse phase is determined based on the superimposed vibration phase. The target value of the inverse phase differs from the superimposed vibration phase by half a vibration cycle. Half a vibration cycle corresponds to 180 degrees in phase angle measurement. The method to determine the target value of the inverse phase is as follows: add 180 degrees to the superimposed vibration phase. If the result of the addition exceeds 360 degrees, subtract 360 degrees to bring it into the range of 0 to 360 degrees. Alternatively, subtract 180 degrees from the superimposed vibration phase. If the result of the subtraction is negative, add 360 degrees to bring it into the positive angle range.

[0119] After determining the inverse phase target value, the phase offset and amplitude adjustment amount to be added to the excitation signal of each smart piezoelectric sensor transducer are calculated so that the synthesized vibration phase generated by the sound wave emitted by each smart piezoelectric sensor transducer at the geometric center of the non-desired sound field accumulation node region is consistent with the inverse phase target value, and the synthesized vibration amplitude is similar to the original superimposed vibration amplitude to form effective cancellation.

[0120] Each of the four intelligent piezoelectric sensing transducers is given an initial additional phase offset and an additional amplitude adjustment. Based on the distance from the installation position of each transducer to the geometric center of the undesired sound field gathering node region, the propagation phase delay of the sound wave from the transducer to the geometric center is calculated. The original vibration phase of the main drive signal of each transducer is added to the additional phase offset and then the propagation phase delay is subtracted to obtain the vibration phase of the additional sound wave emitted by the transducer at the geometric center.

[0121] The additional vibration amplitude of each transducer is set to a certain proportion of the vibration amplitude of the main drive signal. This proportion is determined by the additional amplitude adjustment amount. The additional vibration components generated by the four transducers at the geometric center are synthesized by phasor to obtain the predicted phase and predicted amplitude of the additional synthesized vibration.

[0122] The predicted phase is compared with the target value of the inverse phase. If they are inconsistent, the additional phase offset of each transducer is adjusted until the deviation between the predicted phase and the target value of the inverse phase is less than the allowable value of the phase deviation. At the same time, the additional amplitude adjustment of each transducer is adjusted so that the ratio between the predicted amplitude of the additional synthetic vibration and the original superimposed vibration amplitude is within the amplitude matching range. Since the inverse phase compensation is a fine-tuning intervention of the main sound field, the additional amplitude adjustment is usually set to a small proportion of the amplitude of the main drive signal.

[0123] After calculating the additional phase offset and additional amplitude adjustment required for each intelligent piezoelectric sensor transducer, the phase offset and amplitude adjustment are converted into an inverse phase compensation drive signal added to the drive signal of each intelligent piezoelectric sensor transducer. The inverse phase compensation drive signal is a sinusoidal AC voltage signal with the same frequency as the main drive signal. Its amplitude is equal to the amplitude of the main drive signal multiplied by the additional amplitude adjustment, and its phase is equal to the phase of the main drive signal plus the additional phase offset.

[0124] The specific conversion method is as follows: obtain the waveform parameters of the main drive signal currently applied to each smart piezoelectric sensor transducer, including frequency, amplitude and initial phase. For each smart piezoelectric sensor transducer, take the frequency of the main drive signal as the reference frequency, multiply the amplitude of the main drive signal by the additional amplitude adjustment amount corresponding to the transducer as the compensation signal amplitude, and add the initial phase of the main drive signal to the additional phase offset amount corresponding to the transducer as the initial phase of the compensation signal to generate an inverse phase compensation drive signal.

[0125] The generated inverse phase compensation drive signal is superimposed on the main drive signal in the analog or digital domain. The superimposed composite signal is used as the final output drive signal of the intelligent piezoelectric sensor transducer. The superposition operation can be realized by a signal synthesis circuit. Two sinusoidal voltage signals are connected to the non-inverting input of the adder circuit. The output of the adder is the superimposed drive signal. The superimposed drive signal is applied to each intelligent piezoelectric sensor transducer. The transducer generates an inverse phase compensation vibration component on the basis of the original main vibration.

[0126] It should be further explained that when the phase compensation module generates the inverse phase compensation drive signal, it does not arbitrarily set additional amplitude adjustment and additional phase offset for each smart piezoelectric sensor transducer. Instead, it calculates the compensation amount corresponding to each of the four smart piezoelectric sensor transducers in a coordinated manner based on the location of the non-desired sound field gathering node area, the propagation relationship of each smart piezoelectric sensor transducer to the area at the current frequency point, and the allowable disturbance range of the non-target area on the surface of the light-transmitting sheet.

[0127] For each region of undesired sound field accumulation, the original superimposed vibration amplitude and phase at its geometric center coordinates are first retrieved from the transient sound field distribution description data, and these geometric center coordinates are used as the target compensation point. If the original superimposed vibration amplitude at this target compensation point is denoted as... The original superimposed vibration phase is denoted as The original vibration state at the target compensation point can then be expressed as:

[0128]

[0129] in, This represents the target compensation point, where j is the imaginary unit. The phase compensation module determines the compensation ratio based on the degree of vibration energy concentration in the unwanted sound field accumulation node region, using a natural exponential function. A compensation ratio less than 1 indicates that excessive local vibrations are partially weakened rather than completely eliminated. The compensation ratio can be determined based on the difference between the degree of vibration energy concentration and the upper limit of the desired vibration amplitude. The higher the degree of vibration energy concentration, the larger the compensation ratio. When the degree of vibration energy concentration does not exceed the upper limit of the desired vibration amplitude, no corresponding compensation amount is generated. Thus, the target compensation vibration amount is obtained as follows:

[0130]

[0131] The aforementioned target compensation vibration amount C and the original vibration state at the target compensation point With opposite phases, its function is to form anti-phase superposition at the target compensation point, reducing the vibration amplitude of the undesired sound field accumulation node region to within the desired range. Simultaneously, due to... If the value is less than 1, the vibration at the target compensation point will not be completely canceled out, and the effective cleaning vibration used to strip away contaminants will still be retained.

[0132] After determining the target vibration compensation amount, the phase compensation module calculates the propagation relationship from the four intelligent piezoelectric transducers to the target compensation point. For the i-th intelligent piezoelectric transducer, the propagation distance from its installation position to the target compensation point is obtained. The propagation phase delay is calculated based on the phase velocity of the wave in the light-transmitting sheet at the current frequency sweep point. The amplitude attenuation coefficient is determined based on the propagation distance and the damping characteristics of the light-transmitting sheet material. Thus, the complex propagation coefficient from the i-th intelligent piezoelectric transducer to the target compensation point is obtained.

[0133]

[0134] in, This represents the vibration contribution at the target compensation point after the i-th intelligent piezoelectric sensor transducer outputs a unit compensation signal. This represents the amplitude attenuation coefficient along the path. This represents the propagation phase delay along the path. The complex propagation coefficient reflects both the amplitude and phase changes of the compensation signal from the i-th smart piezoelectric transducer after it propagates to the target compensation point.

[0135] The phase compensation module denotes the uncompensated complex coefficients of the first, second, third, and fourth intelligent piezoelectric sensor transducers as follows: , , and The magnitude of each compensation complex coefficient corresponds to the compensation signal amplitude of the corresponding intelligent piezoelectric sensor transducer, and its phase angle corresponds to the compensation signal phase of the corresponding intelligent piezoelectric sensor transducer. The synthetic compensation vibration formed by the four intelligent piezoelectric sensor transducers at the target compensation point is obtained by the phasor superposition of the four compensation signals after they reach the target compensation point through their corresponding propagation paths.

[0136] To ensure that the synthetic compensation vibration at the target compensation point is close to the target compensation vibration magnitude C, the phase compensation module... , , and The solution aims to minimize the deviation between the combined compensated vibration of the four intelligent piezoelectric transducers at the target compensation point and C. Simultaneously, to avoid significant impact of the compensation signal on other areas of the light-transmitting sheet, the phase compensation module selects several non-target protection grid points outside the desired sound field aggregation node region. These non-target protection grid points include the center and edge regions of the light-transmitting sheet, as well as representative grid points where the original vibration amplitude was within the desired range. For each non-target protection grid point, the amplitude attenuation and phase delay relationships from the four intelligent piezoelectric transducers to that grid point are calculated. Non-target disturbance constraints are incorporated into the solution to ensure that the combined compensated vibration of the four compensation signals at the non-target protection grid points cancels each other out or remains below the allowable disturbance level. The phase compensation module solves for the four compensation complex coefficients according to the following objectives:

[0137]

[0138] Where J represents the compensation allocation evaluation value to be minimized, the first term represents the deviation between the synthetic compensation vibration at the target compensation point and the target compensation vibration amount C, and R represents the comprehensive evaluation value of the compensation vibration amplitude at each non-target protection grid point. The smaller R is, the smaller the impact of the compensation signal on the non-target area. Here, J represents the non-target disturbance suppression weight, used to enhance the constraint effect of non-target protection grid points in compensation allocation. M represents the comprehensive evaluation value of the compensation signal amplitude of the four smart piezoelectric transducers, and represents the compensation amplitude suppression weight, used to prevent the compensation amplitude of a certain smart piezoelectric transducer from being too large. The above solution can be achieved through iterative steps, least squares search, or table lookup approximation, as long as it can reduce J and satisfy the upper limit condition of amplitude. , , and That's all.

[0139] In the specific solution, the phase compensation module first provides the initial compensation complex coefficients for the four intelligent piezoelectric sensor transducers, ensuring that the initial amplitudes of the four compensation signals are all less than a preset proportion of the main drive signal amplitude. Then, it calculates the synthetic compensation vibration of the four compensation signals at the target compensation point. If the phase does not reach the reverse phase direction, the compensation phase of one or more intelligent piezoelectric sensor transducers is adjusted according to the phase deviation at the target compensation point. If the amplitude is lower than the amplitude required for the target compensation vibration, the corresponding compensation amplitude is increased without exceeding the upper limit of the compensation amplitude. After each adjustment, the synthetic compensation vibration at each non-target protection grid point is calculated synchronously. When the compensation vibration at a certain non-target protection grid point exceeds the non-target disturbance threshold... When the value is low, the compensation amplitude of the smart piezoelectric transducer that has a significant impact on the grid point is reduced, or its compensation phase is adjusted so that it cancels out the compensation vibration generated by other smart piezoelectric transducers at the non-target protection grid point. Thus, the four compensation signals are determined collaboratively under the common constraints of the same target compensation point and several non-target protection grid points. The compensation amount of the first smart piezoelectric transducer may be mainly used to provide the dominant anti-phase component required at the target compensation point, while the compensation amounts of the second, third, and fourth smart piezoelectric transducers can be used to correct the phase deviation at the target compensation point and cancel out the additional vibration that may occur in the non-target area.

[0140] The compensation complex coefficients of the i-th intelligent piezoelectric transducer are obtained. Then, the phase compensation module extracts... The modulus value is used as the compensation signal amplitude parameter of the intelligent piezoelectric sensor transducer for extraction. The phase angle is used as the compensation signal phase parameter of the intelligent piezoelectric sensor transducer. If the current main drive signal amplitude is The phase of the main drive signal is Then the reverse phase compensation drive signal of the i-th intelligent piezoelectric sensor transducer can be expressed as:

[0141]

[0142] in, For the reason The additional amplitude adjustment amount obtained from the modulus conversion. For the reason The additional phase offset obtained from the phase angle conversion. ω is the angular frequency corresponding to the current sweep frequency point. The inverse phase compensation drive signal is superimposed with the main drive signal of the i-th intelligent piezoelectric sensor transducer to obtain the final synthetic drive signal applied by the intelligent piezoelectric sensor transducer.

[0143] It should be noted that reverse phase compensation does not require the compensation signal to propagate only at the target compensation point. Instead, it utilizes the phase difference between the compensation vibrations generated on the surface of the light-transmitting sheet by the four intelligent piezoelectric transducers to achieve effective superposition in the reverse phase direction at the target compensation point, while minimizing or canceling each other out at non-target protection grid points. The compensation signal will objectively propagate to other areas of the light-transmitting sheet. However, since the compensation vibrations at non-target protection grid points are already considered as a constraint and an upper limit is set for the compensation amplitude of a single compensation signal during the solution process, the vibration state in non-target areas will not be significantly disturbed. To further ensure the above effect, after applying the reverse phase compensation drive signal, the phase compensation module again collects the electrical response signal through each intelligent piezoelectric transducer and reconstructs the compensated transient sound field distribution description data. If the vibration amplitude in the non-desired sound field aggregation node area is still higher than the expected range after compensation, and the vibration change at the non-target protection grid point does not exceed the non-target disturbance threshold, the compensation ratio is appropriately increased. Alternatively, increase the allocation weight of the target compensation points; if the vibration change at a non-target protection grid point exceeds the non-target disturbance threshold, then reduce the compensation ratio. Increase the weight of non-target disturbance suppression Or lower the upper limit of single-channel compensation amplitude.

[0144] Parameter adjustment module: After the cleaning cycle ends, the cleaning uniformity is evaluated based on the transient sound field distribution description data. When the cleaning uniformity does not meet expectations, the starting frequency and sweep step size of the sweep excitation in the next cleaning cycle are adjusted.

[0145] In this embodiment of the invention, the parameter adjustment module needs to be specifically described. After the cleaning cycle is completed, the parameter adjustment module controls the first, second, third, and fourth intelligent piezoelectric sensor transducers to switch to the sensing working mode so that the sweep frequency signal of the detection power level is applied to each intelligent piezoelectric sensor transducer in sequence. The sweep frequency range and sweep step size are consistent with the cleaning excitation stage.

[0146] At each frequency sweep point, the voltage amplitude signal is obtained through the built-in voltage detection circuit of each intelligent piezoelectric sensor transducer, and the phase difference signal between the driving current and the voltage across the transducer is obtained through the phase comparison circuit to form the electrical response signal after cleaning.

[0147] Based on the electrical response signal after cleaning, the voltage amplitude signal is converted into the vibration excitation intensity at the installation position of each intelligent piezoelectric sensor transducer, and the phase difference signal is converted into the vibration phase. Using the surface of the light-transmitting sheet as a plane coordinate system, the superimposed vibration amplitude and superimposed vibration phase at each discrete grid point are calculated by wave field superposition method to form the transient sound field distribution description data after cleaning.

[0148] Traverse all discrete grid points in the transient sound field distribution description data after cleaning, compare the superimposed vibration amplitude value of each grid point with the lower limit of the expected vibration amplitude range, and mark the grid points whose superimposed vibration amplitude value is less than the lower limit as grid points not covered by cleaning.

[0149] The total number of uncovered grid points is counted, and the percentage of missing clean coverage is obtained by dividing the total number of all discrete grid points on the surface of the light-transmitting sheet by the total number of uncovered grid points.

[0150] When the proportion of missing cleaning coverage is greater than the first reference value for missing coverage, the cleaning uniformity is determined to be unsatisfactory.

[0151] Analyze the spatial distribution of uncovered grid points on the surface of the light-transmitting sheet. When the uncovered grid points are concentrated in the edge area of ​​the light-transmitting sheet, adjust the starting frequency of the next cleaning cycle to a lower frequency. When the uncovered grid points are concentrated in the center area of ​​the light-transmitting sheet, adjust the starting frequency of the next cleaning cycle to a higher frequency or expand the upper limit of the frequency range. When the uncovered grid points are distributed in a discrete spot-like pattern, reduce the frequency sweep step size of the next cleaning cycle.

[0152] It should be noted that when the cleaning uniformity does not meet expectations, the starting frequency and sweep step size of the frequency sweep excitation in the next cleaning cycle should be adjusted. The cleaning cycle refers to the time interval from the start of frequency sweep excitation, through the construction of sound field distribution, identification of unwanted nodes and application of reverse phase compensation, until the surface of the light-transmitting sheet completes one complete cleaning operation.

[0153] The first step in assessing the uniformity of cleaning is to acquire the electrical response signal again through each intelligent piezoelectric sensor transducer after the cleaning cycle ends, and construct transient sound field distribution description data after cleaning. At the end of the cleaning cycle, each intelligent piezoelectric sensor transducer stops outputting the main drive signal and the reverse phase compensation drive signal, and switches to pure sensing working mode. A sweep frequency controller generates a set of sweep frequency signals that are the same as the cleaning excitation, but the power level is reduced to the detection level, and is applied to the first intelligent piezoelectric sensor transducer, the second intelligent piezoelectric sensor transducer, the third intelligent piezoelectric sensor transducer, and the fourth intelligent piezoelectric sensor transducer in sequence.

[0154] At each sweep frequency point, the voltage amplitude signal is obtained through the voltage detection circuit built into the intelligent piezoelectric sensor transducer, and the phase difference signal between the driving current and the voltage across the transducer is obtained through the phase comparison circuit, forming the electrical response signal after cleaning. The acquisition frequency range and sweep step size of the electrical response signal after cleaning are consistent with those of the cleaning excitation stage to facilitate the comparability of the sound field distribution before and after cleaning.

[0155] After obtaining the electrical response signal after cleaning, the voltage amplitude signal is converted into the vibration excitation intensity at each transducer installation position through the signal conditioning unit built into the intelligent piezoelectric sensor transducer in the same way as the construction of transient sound field distribution description data. The phase difference signal is converted into vibration phase. Using the surface of the light-transmitting sheet as the plane coordinate system, the superimposed vibration amplitude and superimposed vibration phase at each discrete grid point are calculated by wave field superposition method to form the transient sound field distribution description data after cleaning.

[0156] After obtaining the transient sound field distribution description data after cleaning, the superimposed vibration amplitude of each discrete grid point in the transient sound field distribution description data after cleaning is compared with the expected vibration amplitude range. The proportion of grid points with superimposed vibration amplitude below the lower limit of the expected vibration amplitude range is counted as the cleaning coverage missing ratio. The expected vibration amplitude range is a vibration amplitude range determined by the peeling threshold of typical contaminants on the surface of the light-transmitting sheet and the fatigue limit of the light-transmitting sheet material. Its lower limit is the minimum vibration amplitude that can effectively peel off contaminants, and its upper limit is the maximum allowable vibration amplitude that avoids damage to the light-transmitting sheet or transducer structure.

[0157] The comparison operation iterates through each discrete grid point in the transient sound field distribution description data array after cleaning, reads the superimposed vibration amplitude value of the discrete grid point, and determines whether the superimposed vibration amplitude value is less than the lower limit of the expected vibration amplitude range. If it is less than the lower limit, the discrete grid point is marked as a grid point not covered by cleaning. If it is greater than or equal to the lower limit, it is marked as a grid point covered by cleaning. After the traversal is completed, the total number of grid points not covered by cleaning is counted, and the total number of all discrete grid points on the surface of the light-transmitting sheet is also counted. The ratio obtained by dividing the total number of grid points not covered by cleaning by the total number of all discrete grid points is the cleaning coverage missing ratio. The cleaning coverage missing ratio reflects the area of ​​the light-transmitting sheet surface where the vibration energy is insufficient to achieve effective cleaning. The higher the missing ratio, the larger the cleaning blind area and the worse the cleaning uniformity.

[0158] When the percentage of missing cleaning coverage exceeds the first reference value for missing coverage, the cleaning uniformity is deemed not to have met expectations. The first reference value for missing coverage is a threshold value for the percentage of missing coverage determined according to the cleaning process quality acceptance standards. For example, a missing percentage exceeding a certain percentage is considered unqualified. If the percentage of missing cleaning coverage is less than or equal to the first reference value for missing coverage, the cleaning uniformity is deemed to have met expectations. The next cleaning cycle can use the current sweep frequency parameters or make minor adjustments according to the preset maintenance cycle. If the percentage of missing cleaning coverage exceeds the first reference value for missing coverage, the cleaning uniformity is deemed not to have met expectations. In this case, it is necessary to adjust the starting frequency and sweep frequency step size of the sweep frequency excitation in the next cleaning cycle.

[0159] The adjustment method is as follows: Analyze the spatial distribution of the uncovered grid points on the surface of the light-transmitting sheet. If the uncovered grid points are concentrated in the edge area of ​​the light-transmitting sheet, it indicates that the current frequency sweep interval is insufficient for the excitation of the edge modes. Then, the frequency sweep start frequency of the next cleaning cycle is moved to a lower frequency direction to enhance the excitation of the low-frequency bending wave mode in the edge area.

[0160] If the grid points not covered by cleaning are concentrated in the central area of ​​the transparent sheet, the starting frequency of the sweep frequency is moved to a higher frequency or the upper limit frequency of the sweep frequency range is expanded. If the grid points not covered by cleaning are distributed in a discrete spot-like pattern, it indicates that the current sweep frequency step size is too large and some effective resonant frequency points are missed. In this case, the sweep frequency step size of the next cleaning cycle is reduced and the number of sweep frequency points is increased to capture multiple resonant modes of the transparent sheet with a denser frequency step.

[0161] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0162] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0163] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0164] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0165] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of protection of the described technical solution.

Claims

1. A vibration control system for ultrasonic cleaning of camera lenses, characterized in that, include: Data acquisition module: acquires electrical response signals collected by several intelligent piezoelectric sensor transducers arranged on the edge of the lens during frequency sweep excitation. The electrical response signals include voltage amplitude signals and current phase signals at both ends of each intelligent piezoelectric sensor transducer. Sound field distribution construction module: Based on the electrical response signal, the transient sound field distribution description data of the lens lens during the current cleaning cycle is constructed through the signal conditioning unit built into the intelligent piezoelectric sensor transducer. The transient sound field distribution description data is used to characterize the vibration amplitude distribution and vibration phase distribution at each spatial position on the surface of the lens lens. Node identification module: Based on the transient sound field distribution description data, it identifies the unwanted sound field gathering node regions appearing on the surface of the light-transmitting sheet, and determines the spatial location and vibration energy concentration of the unwanted sound field gathering node regions; Phase compensation module: Based on the spatial location and vibration energy concentration of the identified unwanted sound field gathering node area, an inverse phase compensation drive signal is generated and superimposed on the drive signal of the corresponding intelligent piezoelectric sensor transducer to reduce the vibration amplitude of the unwanted sound field gathering node area. Parameter adjustment module: After the cleaning cycle ends, the cleaning uniformity is evaluated based on the transient sound field distribution description data. When the cleaning uniformity does not meet expectations, the starting frequency and sweep step size of the sweep excitation in the next cleaning cycle are adjusted.

2. The vibration control system for ultrasonic cleaning of camera lenses according to claim 1, characterized in that, The data acquisition module has a first intelligent piezoelectric sensor transducer, a second intelligent piezoelectric sensor transducer, a third intelligent piezoelectric sensor transducer, and a fourth intelligent piezoelectric sensor transducer arranged at equal intervals along the circumferential direction at the edge of the lens light-transmitting sheet, and the central angle interval between adjacent intelligent piezoelectric sensor transducers is a right angle. A sweep frequency drive signal is generated by a sweep frequency controller. The sweep frequency drive signal changes the frequency sequentially in the first frequency range to the second frequency range with a preset sweep frequency step size. The lower limit of the first frequency range is located near the series resonant frequency of the intelligent piezoelectric sensor transducer, and the upper limit of the second frequency range is located near the parallel resonant frequency of the intelligent piezoelectric sensor transducer.

3. The vibration control system for ultrasonic cleaning of a camera lens according to claim 2, characterized in that, At each frequency sweep point, the frequency sweep drive signal is amplified and simultaneously applied to four intelligent piezoelectric sensor transducers. After continuous excitation until steady-state vibration, the voltage amplitude signal at both ends of the transducer is collected through the built-in voltage detection circuit of each intelligent piezoelectric sensor transducer, and the phase difference signal between the drive current and the voltage at both ends of the transducer is collected through the built-in phase comparison circuit of each intelligent piezoelectric sensor transducer. The voltage amplitude and phase difference signals of the first, second, third, and fourth intelligent piezoelectric transducers at the same sweep frequency point are grouped into one data group. All data groups are arranged in ascending order of sweep frequency point to form an electrical response signal.

4. The vibration control system for ultrasonic cleaning of camera lenses according to claim 1, characterized in that, For each frequency sweep point, the sound field distribution construction module acquires the voltage amplitude signal and phase difference signal of the first, second, third, and fourth intelligent piezoelectric transducers at that frequency sweep point. Divide the voltage amplitude signal of each intelligent piezoelectric sensor transducer by the electrode spacing of the transducer to obtain the electric field strength value. Multiply the electric field strength value by the piezoelectric strain constant to obtain the mechanical strain amplitude. Multiply the mechanical strain amplitude by the stiffness coefficient of the contact surface between the transducer and the light-transmitting sheet to obtain the vibration excitation intensity at the installation position of the corresponding intelligent piezoelectric sensor transducer. The phase difference signal of each intelligent piezoelectric sensor transducer is demodulated to obtain the phase difference between the driving current and the terminal voltage. The vibration phase at the corresponding installation position is calculated based on the phase relationship between the branch current and the mechanical vibration component in the equivalent circuit model of the transducer. Using the surface of the light-transmitting sheet as a planar coordinate system, the installation position coordinates of each intelligent piezoelectric sensor transducer are taken as excitation points. For each discrete grid point on the surface of the light-transmitting sheet, the phase delay and amplitude attenuation coefficient of the wave emitted from each excitation point when it propagates to the grid point are calculated respectively. The phase delay is obtained by dividing the distance between the excitation point and the grid point by the phase velocity of the wave at that frequency and then multiplying by the angular frequency.

5. The vibration control system for ultrasonic cleaning of a camera lens according to claim 4, characterized in that, The vibration phase at each excitation point is obtained by subtracting the corresponding phase delay from the vibration phase at each excitation point. The vibration amplitude at each excitation point is obtained by multiplying the vibration excitation intensity at each excitation point by the corresponding amplitude attenuation coefficient. The vibration components generated at the same grid point by each excitation point are vector superimposed using phasor addition. The magnitude of the composite vector is taken as the superimposed vibration amplitude, and the phase angle of the composite vector is taken as the superimposed vibration phase. The vibration amplitude and phase of each discrete grid point are superimposed and arranged according to the grid row and column positions to form the transient sound field distribution description data corresponding to the frequency sweep points.

6. The vibration control system for ultrasonic cleaning of camera lenses according to claim 1, characterized in that, In the transient sound field distribution description data, the node identification module traverses each discrete grid point on the surface of the light-transmitting sheet. For each grid point, it obtains the superimposed vibration amplitude value of the grid point and the superimposed vibration amplitude values ​​of all adjacent grid points directly adjacent to the grid point in the row or column direction. It calculates the arithmetic mean of the superimposed vibration amplitude values ​​of adjacent grid points as the neighborhood average amplitude. The absolute value of the difference between the superimposed vibration amplitude value of the grid point and the neighborhood average amplitude is divided by the neighborhood average amplitude to obtain the amplitude deviation ratio. When the amplitude deviation ratio of a certain grid point exceeds the first amplitude deviation reference value, and the superimposed vibration amplitude of all grid points in the connected region formed by searching for adjacent grid points with the grid point as the seed point and satisfying the superimposed vibration amplitude greater than the first amplitude reference value is greater than the first amplitude reference value, the connected region is identified as a non-desired sound field gathering node region.

7. The vibration control system for ultrasonic cleaning of a camera lens according to claim 6, characterized in that, The geometric center row coordinates are obtained by summing the row coordinates of all grid points within the region of the unwanted sound field gathering node and dividing the sum by the total number of grid points. The geometric center column coordinates are obtained by summing the column coordinates of all grid points and dividing the sum by the total number of grid points. The geometric center row coordinates and geometric center column coordinates are used as the spatial location of the region of the unwanted sound field gathering node. The arithmetic mean of the sum of the superimposed vibration amplitude values ​​of all grid points in the unwanted sound field clustering node region and divided by the total number of grid points is used as the degree of vibration energy concentration in the unwanted sound field clustering node region.

8. The vibration control system for ultrasonic cleaning of camera lenses according to claim 1, characterized in that, For each identified unwanted sound field clustering node region, the phase compensation module obtains the superimposed vibration phase value at the geometric center coordinates of the unwanted sound field clustering node region from the transient sound field distribution description data. Based on the superimposed vibration phase value, add 180 degrees to the superimposed vibration phase value to obtain the inverse phase target value. When the sum exceeds 360 degrees, subtract 360 degrees to return to the range of 0 to 360 degrees. The inverse phase target value and the superimposed vibration phase value differ by half a vibration cycle. Initial additional phase offset and initial additional amplitude adjustment are set for the first, second, third and fourth intelligent piezoelectric sensor transducers, respectively. The propagation phase delay is calculated based on the distance from the installation position of each intelligent piezoelectric sensor transducer to the geometric center coordinates. The original vibration phase of the main drive signal of each intelligent piezoelectric sensor transducer is added to the additional phase offset and then the propagation phase delay is subtracted to obtain the vibration phase of each additional sound wave at the geometric center. The vibration phases of each additional sound wave are then synthesized by phasor to obtain the additional synthesized vibration prediction phase.

9. A vibration control system for ultrasonic cleaning of a camera lens according to claim 8, characterized in that, Adjust the additional phase offset of each intelligent piezoelectric sensor transducer until the deviation between the additional synthetic vibration prediction phase and the target value of the inverse phase is less than the allowable value of the phase deviation. Adjust the additional amplitude adjustment of each intelligent piezoelectric sensor transducer until the ratio between the additional synthetic vibration prediction amplitude and the original superimposed vibration amplitude at the geometric center is within the amplitude matching range. The adjusted additional phase offset and additional amplitude adjustment are converted into a sinusoidal AC voltage signal with the same frequency as the main drive signal as the inverse phase compensation drive signal. The amplitude of the inverse phase compensation drive signal is the amplitude of the main drive signal multiplied by the additional amplitude adjustment, and the phase of the inverse phase compensation drive signal is the phase of the main drive signal plus the additional phase offset. The inverse phase compensation drive signal is superimposed on the main drive signal and applied to the corresponding intelligent piezoelectric sensor transducer.

10. A vibration control system for ultrasonic cleaning of a camera lens according to claim 1, characterized in that, After the cleaning cycle ends, the parameter adjustment module controls the first, second, third, and fourth intelligent piezoelectric sensor transducers to switch to the sensing working mode so that the sweep frequency signal of the detection power level is applied to each intelligent piezoelectric sensor transducer in sequence, and the sweep frequency range and sweep frequency step size are consistent with the cleaning excitation stage. At each frequency sweep point, the voltage amplitude signal is obtained through the built-in voltage detection circuit of each intelligent piezoelectric sensor transducer, and the phase difference signal between the driving current and the voltage across the transducer is obtained through the phase comparison circuit to form the electrical response signal after cleaning. Based on the electrical response signal after cleaning, the voltage amplitude signal is converted into the vibration excitation intensity at the installation position of each intelligent piezoelectric sensor transducer, and the phase difference signal is converted into the vibration phase. Using the surface of the light-transmitting sheet as a plane coordinate system, the superimposed vibration amplitude and superimposed vibration phase at each discrete grid point are calculated by wave field superposition method to form the transient sound field distribution description data after cleaning. Traverse all discrete grid points in the transient sound field distribution description data after cleaning, compare the superimposed vibration amplitude value of each grid point with the lower limit of the expected vibration amplitude range, and mark the grid points whose superimposed vibration amplitude value is less than the lower limit as grid points not covered by cleaning. The total number of uncovered grid points is counted, and the percentage of missing clean coverage is obtained by dividing the total number of all discrete grid points on the surface of the light-transmitting sheet by the total number of uncovered grid points. When the proportion of missing cleaning coverage is greater than the first reference value for missing coverage, the cleaning uniformity is determined to be unsatisfactory. Analyze the spatial distribution of uncovered grid points on the surface of the light-transmitting sheet. When the uncovered grid points are concentrated in the edge area of ​​the light-transmitting sheet, adjust the starting frequency of the next cleaning cycle to a lower frequency. When the uncovered grid points are concentrated in the center area of ​​the light-transmitting sheet, adjust the starting frequency of the next cleaning cycle to a higher frequency or expand the upper limit of the frequency range. When the uncovered grid points are distributed in a discrete spot-like pattern, reduce the frequency sweep step size of the next cleaning cycle.

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