System for ultrasonic cleaning

Abstract

Described is a system for ultrasonic cleaning of a surface, a corresponding method, and a use of the system for cleaning a surface. The method for clearing a contamination from a surface is comprising: generating first ultrasonic waves; coupling the first ultrasonic waves to the surface; receiving at least some of the first ultrasonic waves; detecting a change in one or more characteristics of a plurality of characteristics of the at least some of the first ultrasonic waves in the; determining a cleaning action for the surface from a set of predefined cleaning actions based on the detected change in the one or more characteristics; generating second ultrasonic waves; and coupling the second ultrasonic waves to the surface in accordance with the determined cleaning action.

Description

(19) *EP004725620A1* (11) EP 4 725 620 A1 (12) EUROPEAN PATENT APPLICATION (43) Date of publication: 15.04.2026 Bulletin 2026 / 16 (21) Application number: 24205244.7 (22) Date of filing: 08.10.2024 (51) International Patent Classification (IPC): B08B 7 / 02 (2006.01) (52) Cooperative Patent Classification (CPC): B08B 7 / 028 (84) Designated Contracting States: AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC ME MK MT NL NO PL PT RO RS SE SI SK SM TR Designated Extension States: BA Designated Validation States: GE KH MA MD TN (71) Applicant: Echovista Ultrasound Surface Cleaning Ltd. Hampshire SO51‑9AW (GB) (72) Inventors: • Shin, Mincheol Eastleigh, SO53 2BG (GB) • Page, Harry Surrey, GU98DU (GB) • Odling-Thomas, Joshua Keaton Chichester, PO20 3RZ (GB) • Walter, Steffen 64832 Babenhausen (DE) (74) Representative: Herrmann, Daniel Boehmert & Boehmert Anwaltspartnerschaft mbB Pettenkoferstrasse 22 80336 München (DE) (54) SYSTEM FOR ULTRASONIC CLEANING (57) Described isasystem forultrasonic cleaningofa surface, a corresponding method, and a use of the sys- tem for cleaning a surface. The method for clearing a contamination from a surface is comprising: generating first ultrasonic waves; coupling the first ultrasonic waves to the surface; receiving at least some of the first ultra- sonic waves; detecting a change in one or more char- acteristics of a plurality of characteristics of the at least some of the first ultrasonic waves in the; determining a cleaning action for the surface from a set of predefined cleaningactionsbasedon thedetectedchange in theone or more characteristics; generating second ultrasonic waves; and coupling the second ultrasonic waves to the surface in accordance with the determined cleaning action. EP 4 72 5 62 0 A 1 Processed by Luminess, 75001 PARIS (FR) 2 1 EP 4 725 620 A1 2 Description TECHNICAL FIELD

[0001] The present invention relates to a system for ultrasonic cleaning of a surface, a corresponding meth- od, and a use of the system for cleaning a surface. BACKGROUND

[0002] Surfaces such as glass plates in windows, pro- tective covers of optical viewing equipment, mirrors and others are typically subject to contamination, such as by rain,mudorothermedia.Such contaminationmay impair the visibility through such a surface or may be harmful to the surface or a coating applied to the surface, such that cleaning of the surface becomes necessary. Mechanical means of cleaning may themselves be harmful to the surface or a coating.Wipers or clothsmay themselves be designed to gently contact the surface. However, the content of the contamination, such as grains of sand or other particles may be harmful in such scenarios inde- pendent of the design of the mechanical means for cleaning the surface. Additionally, mechanical surface cleaning means themselves may occlude visibility through a glass surface during cleaning of the surface. In the state of the art, ultrasonic cleaning methods for surfaces havebeen described, inwhich ultrasonicwaves are used to clean surfaces instead ofmechanicalmeans. Furthermore, in order to reduce the stress on the com- ponents of the cleaning systems and the surface to be cleaned, detection methods have been described, wherein the cleaning is only carried out when a contam- ination is sensed. However, ultrasonic cleaning of sur- faces is not as reliable asmechanical means in removing contamination completely. SUMMARY

[0003] It is thus an object of the present invention to provide a system which is capable of cleaning surfaces more reliably.

[0004] This object is achieved by a system as defined by independent claim 1, by a method as defined by claim 11 and by the use of a system of claims 1 to 10 according to claim 15.

[0005] The inventors have realized that the reliability of ultrasonic cleaning of a surface depends on the contam- ination present on the surface. While the detection of the presence of a contamination allows for efficient use of the cleaning system (e.g. no power is wasted on operating the systemwhen no contamination is present), a general mode of cleaning does not reliably remove contamina- tions. The inventors have, thus, realised that in order to increase the reliability of ultrasonic cleaning, tailored cleaning actions are beneficial, whereby in a systemable to detect the presence of a contamination, different de- tections lead to different cleaning actions of the system, thereby increasing the reliability and efficiency of clean- ing according to the contamination.

[0006] According to ageneral aspect of the invention, a system for clearing a contamination from a surface is provided, the systemcomprising: oneormoreultrasound transducers configured to couple ultrasonic waves to the surface; at least one generator configured to generate a drive signal to drive the one or more transducers; a receiver configured to receive at least some of the ultra- sonic waves coupled to the surface; and a control unit; wherein the control unit is configured to: cause the at least one generator to generate a first drive signal to drive the one or more transducers; cause at least one of the oneormore transducers toproducefirst ultrasonicwaves in accordance with the first drive signal to couple the first ultrasonicwaves to the surface; detect a change in oneor more characteristics of a plurality of characteristics of at least some of the first ultrasonic waves received by the receiver; determine a cleaning action for the surface from a set of predefined cleaning actions based on the de- tected change in the one or more characteristics; cause the at least one generator to generate a second drive signal in accordancewith the determined cleaning action to drive at least a portion of the one or more transducers; and cause the portion of the one or more transducers to produce second ultrasonic waves in accordance with the second drive signal to couple the second ultrasonic waves to the surface.

[0007] By detecting change in one or more character- istics of a plurality of characteristics of the first ultrasonic waves in the received at least some of the first ultrasonic waves, a cleaning action corresponding to the detected change may be determined and performed. Thus, the cleaning of the surface may be suited to the specific detected change, allowing for more reliable and efficient cleaning.

[0008] In an aspect of the invention, the control unit is further configured to infer a type of the contamination on the surface from a predefined set of types of contamina- tions from the detected change in the one or more char- acteristics of the at least some of the first ultrasonic waves and wherein the determined cleaning action cor- responds to the inferred type of the contaminationwhere- in the predefined set of types of contaminations com- prises at least one of ice fog / condensation mud, dust, biological matter (e.g., protein) and liquid (e.g. droplets). In another aspect of the invention, the predefined set of cleaning actions may comprise at least one cleaning action for every type of contamination. The predefined set of cleaning actions may also comprise one cleaning action for every detected change in the one or more characteristics in thepredefinedset of detectedchanges.

[0009] By inferring the type of the contamination, dif- ferent detected changes in one ormore characteristics of the at least some of the received first ultrasonic waves may be grouped together. Thus, cleaning actions which are applicable tomore than one detected change, can be efficiently mapped to all relevant detected changes, al- 5 10 15 20 25 30 35 40 45 50 55 3 3 EP 4 725 620 A1 4 lowing for better categorization of detected changes and applicable cleaning actions allowing for more efficient cleaning of the surface. Furthermore, the predefined set of cleaning actions can be better tailored to the types of contamination. Moreover, in systems in which a user interacts with the system, representation of a detected change as a type of the contamination is helpful, since users are typically unable to properly distinguish, com- pare or otherwise usefully analyse changes in ultrasonic waves reliably or understand in detail the content of such changes. The above-mentioned types of contamination represent the most common types of contamination, such that the inclusion of any one of these allows for more reliable and complete cleaning of the surface.

[0010] The characteristics may be characteristics that define theultrasonicwave, suchas frequency, amplitude, and / or phase. In an aspect of the invention, the control unit is configured to detect the change in the one or more characteristics of the at least some of the first ultrasonic waves by comparing the at least some of the first ultra- sonic waves to a base level signal, and / or wherein the detected change is a change in the waveform or fre- quency characteristics of the at least some of the first ultrasonic waves, wherein, preferably, the detected change is at least one of the power level, the frequency spectrum and the amplitude of the ultrasonic detection waves.

[0011] The detection of the change in one or more characteristics of the received at least some of the first ultrasonic waves may be more reliable when done by comparisonwith a base level signal. Factors, such as the dimensions of the surface, thematerial of the surface, the placement of the transducers and the receiver relative to one another and other optional objects may all influence the first ultrasonic waves while travelling from one of the transducers to the receiver. Thus, inorder tomore reliably detect changes in one or more characteristics of the received at least some of the first ultrasonic waves, the comparison with such a base level is beneficial. The ultrasonic waves coupled to the surface, travel through thesurfaceandaresubject to several effectsaccording to the properties of the surface, such as the surface materi- al, dimensions etc. For example, ultrasonic waves are subject to attenuation due to energy dissipation. For example, the first ultrasonic waves may be partially coupled into a contamination present on the surface at the boundary between the surface and the contamina- tion. Different media, however, also have different dis- sipative properties, such that the attenuation may be stronger or weaker than in the material of the surface or may be more or less pronounced at different frequen- cies, such that adetectedchange inacharacteristic of the received at least some of the first ultrasonic detection waves allows the control unit to determine the appropri- ate corresponding cleaning action. The detected changes may vary depending on the parameters of the system, environmental conditions and parameters of the surface. For example, the dimensions of the surface, the material of the surface, the ambient temperature, the distance between the transducer(s) and the receiver etc. may all influence the ultrasonic waves in the surface. Thus, in another aspect of the invention, the systemmay be calibrated to the surface and conditions in which it is applied. This may also entail calibrating the base level signal accordingly, e.g. by recording such a base level signal in the conditions to which the system is applied.

[0012] In an aspect of the invention, the one or more transducers comprise at least two transducers, and wherein one of the at least two transducers functions as the receiver.

[0013] By comprising at least two transducers, the system is capable of more thoroughly cleaning the sur- face since a large number of combinations of second ultrasonic waves may be applied according to the clean- ing actions determined by the control unit. Furthermore, due to the attenuation of the waves in the surface and contaminations and the general inverse square law, the use of at least two transducers reduces the energy con- sumption of the system at equal performance.When one of the at least two transducers functions as the receiver for the first ultrasonic waves, a further component of the system isnot requiredsuch that thesystembecomes less complex, requires fewer components, and can, thus, be incorporated into other systems or environments more easily.

[0014] In an aspect of the invention, the control unit is configured to assess,whether the detected change in the one or more characteristics crosses a threshold value, such that the cleaning action to be performed is only determined and / or performedwhen the detected change in the one or more characteristics crosses the threshold value. The system preferably further comprises: a trans- ceiver configured to detect environmental conditions, wherein the detectable environmental conditions include at least oneof temperature, humidityandair flow,wherein the control unit is configured to receive information con- veying the detected environmental conditions and deter- mine the cleaning action based also on the received information, and wherein, preferably, the control unit is configured to adapt the threshold value to the environ- mental conditions based on the received information. The environmental conditions may be the conditions prevailing in the vicinity of the surface and / or the trans- ducers.

[0015] By making the determination and / or perfor- mance of the cleaning action conditional on whether the detected change crosses a threshold value, unne- cessary operation of the system to clean the surface is mitigated. For example, when the amount of contamina- tion on the surface is negligible it is inefficient for the system to perform the cleaning action, since this may unfeasibly increase the frequency of performing said action. Furthermore, the use of a threshold value allows the system to be more robust to outliers in detected changes in the one or more characteristics of the re- ceived at least some of the first ultrasonic waves, which 5 10 15 20 25 30 35 40 45 50 55 4 5 EP 4 725 620 A1 6 may be caused by factors external to the system. It is further beneficial for the control unit to be configured to infer the type of the contamination based also on the received information conveying the environmental con- ditions detected by the transceiver. For example, when the environmental temperature is particularly low, e.g. ‑20°C, thismaybean indicator that contaminationswhich are similar to water may be snow, ice or sleet. In another aspect of the invention the control unit is thus configured to base the determination of the cleaning action corre- sponding to the detected change in one or more char- acteristics of the received at least some of the first ultra- sonic waves and / or the inferring of the type of the con- tamination also on the received information conveying the environmental conditions. Environmental conditions suchas the temperature, humidity or air flowmaycausea change in the characteristics of the received at least some of the ultrasonic waves. Dispersion properties typically depend on the temperature, such that the threshold value may be inadvertently crossed even though no contamination or only a negligible amount of contamination is present. Furthermore, the ambient hu- midity may change the electrical properties of compo- nents of the system, such that the threshold values may also be crossed due to artefacts in the electrical commu- nications between components. In order to prevent mis- detections and unnecessary determination / performance of cleaningactions, causing inefficientuseof resources, it is beneficial for the control unit to be able to adapt the threshold values accordingly.

[0016] In an aspect of the invention, the system further comprises: a liquid supply apparatus configured to sup- ply liquid, preferably water, to the surface; wherein the control unit is configured to cause the liquid supply ap- paratus to supply liquid to the surface in accordance with the determined cleaning action, preferably wherein the transducers are configured to couple ultrasonic waves to the liquid through the surface and / or directly, and / or wherein the control unit is configured to cause the liquid supply apparatus to supply liquid in accordance with the detected type of contamination.

[0017] For some contaminations it can be useful for liquid to be supplied to the surface. The supplied liquid may dissolve contaminations such that cleaning of the surface is facilitated. The transducers may couple ultra- sonic waves to the liquid directly, when the liquid is in contact with the transducers. The transducers may also couple ultrasonic waves to the liquid indirectly through the surface to which the liquid has been applied. The liquid may surround the contamination after being sup- plied to the surface. Thus, the area of contact between the contamination and a medium carrying the ultrasonic waves (e.g. the surface and / or the liquid) is increased allowing for an enhanced determination of the cleaning action and cleaning of the surface. For example, when rain or other liquid is detected on the surface, the useful- ness of liquid in the cleaning action is low. Thus, the control unit may not cause the liquid supply apparatus tosupply liquid to thesurface insuchascenario,when the cleaning action does not entail such a supply of liquid. However, when in an example the detected contamina- tion type is mud, biological matter (e.g., protein), dust or any further such type, the supply of liquid can increase the effectiveness of the second ultrasonic waves. Furthermore, the liquid can dissolve the contamination at least in part. Additionally, the liquid supplied to the surface may be caused by the cleaning action to be propelled to the edge of the surface and may in this manner collide and loosen the contamination. Thus, a more reliable cleaning may be achieved.

[0018] In an aspect of the invention, the system com- prises a power amplifier configured to amplify the power of the generated first and / or second drive signals; where- in the power amplifier is configured to be operable in at least two differentmodes, eachmode corresponding to a different amount of amplification; wherein the control unit is configured to cause at least some of the portion of the one or more transducers to produce ultrasonic waves drivenbydifferently amplifieddrive signals in accordance with the determined cleaning action.

[0019] By being configured to adjust the power level of the ultrasonic waves produced by the transducers and coupled to the surface, the system is enabled to perform cleaning actions corresponding to different types of con- taminations, which may have different properties. In an aspect of the invention, the power level may be adjusted such that the transducersmay at least be able to operate at a base power level and a high power level. The high power level may correspond to approximately twice the power of the base power level. In a further aspect the power level may be adjusted such that the transducers may further be able to operate at a low power level. The lowpower levelmay, for example, correspond to approxi- mately one fifth of the base power level. In another aspect, the power level may be adjusted such that the transducers may further be able to operate at further power levels between the low and the high power level and / or below the low power level and / or above the high power level. Thus, different contaminations may be cleaned in amanner corresponding to the contamination. For example, denser contaminations may require higher power levels for propulsion than less dense contamina- tions. In another example, heat may be generated in a contamination by applying a high power level. In yet another example, small droplets (liquid), as for example are present in condensation or fog, may be reliably cleanedusing lowpower levels, thus reducing the energy consumption of the system.

[0020] In an aspect of the invention, the at least one generator comprises a pulse generator, such that the at least one generator is configured to be able to produce pulsed drive signals, and wherein the control unit is configured to adjust the pulse frequency and / or duration, preferably wherein the control unit is configured to cause synchronously and / or asynchronously pulsed ultrasonic waves to be produced by different transducers of the 5 10 15 20 25 30 35 40 45 50 55 5 7 EP 4 725 620 A1 8 portionof oneormore transducers. In yet another aspect, thecontrol unit is configured toadjust thepulse frequency and / or duration according to the determined cleaning action for one or more transducers of the portion of the one or more transducers.

[0021] Pulsedsecondultrasonicwavesallow for quick- er propulsion of liquid (e.g, droplets) across the surface. Individual pulsing of the transducers allows for complex and efficient cleaning actions. Additionally, the stress induced in the surface by the ultrasonic waves may be reduced, which is beneficial for the longevity and stability of the surface. Furthermore, the energy consumption of the system may be reduced when pulsed ultrasonic waves are produced. The complexity of the superim- posed (first / second) ultrasonic waves in the surface may be adapted to the needs of the system in detecting changes in the characteristics of the received at least some of the first ultrasonic waves or in performing the determined cleaning actions by allowing synchronous and asynchronous pulsing sequences for different trans- ducers. For example, asynchronous pulsing of two op- posite transducers during synchronous, non-pulsed ac- tivation of a third transducer allows particularly efficient removal of liquid liquid (e.g. droplets) from the surface.

[0022] In an aspect of the invention, the control unit is configured to cause the at least one generator to mod- ulate the first and / or second drive signal in accordance with the determined cleaning action, wherein at least one of the amplitude, the frequency and the phase shift of the first and / or second drive signal is modulated.

[0023] For the detection of contaminations on the sur- face, the control unit may cause modulation of the am- plitude, frequency or phase shift of the ultrasonic waves produced by the one or more transducers. For example, for the detection of contaminations it is beneficial for the transducers to couple ultrasonic waves with multiple different frequencies into the surface, such that the de- tectionof a change in theoneormore characteristicsmay be a change in a single frequency. For example, a con- taminationmayattenuate ultrasonicwaves of a particular frequency strongly, while attenuating waves of other frequencies to a lesser degree. Thus, the control unit may be able to determine the corresponding cleaning actionproperly. Furthermore, the control unitmaybeable to infer the type of the contamination from the detected change. In cleaning the surface, the same principle ap- plies. For example, a higher amplitude may lead to a higher transmission of energy to a contamination, which in turn may lead to faster evaporation, quicker propaga- tion or other beneficial effects. Modulating the frequency maybebeneficial in order to causeultrasonicwaves tobe caused to be coupled into the surface in, thus, into the contamination the frequency of whichmay correspond to a resonant frequency / eigenmodeor a harmony of such a frequency of the contaminant, which causes a stronger effect of the ultrasonic waves in the contamination. Furthermore, ultrasonic waves of the resonant frequen- cy / eigenmode or a harmony thereof of the surface may becaused to becoupled into the surface in order to cause strong vibrations in the surface.

[0024] In an aspect of the invention, the control unit is configured tocalculatea liquidsaturationofaboundaryof the contamination based on a liquid flow rate of the liquid supplied by the liquid supply apparatus, and cause the portionof theoneormore transducers to producesecond ultrasonic waves in accordance with the determined cleaning action and in accordance with the calculated liquid saturation.

[0025] When the liquid saturation of the boundary of thecontamination ishigh, theareaof contact between the contamination and media which may couple the second ultrasonicwaves to thecontamination is increased.Thus, a more effective, reliable and efficient cleaning of the surface is facilitated. Additionally, cavitations caused in the liquid by the second ultrasonic waves may cause microjets and / micro bubbles, which in turn may loosen the contamination. When a larger proportion of the boundary of the contamination is saturated by the liquid such cavitations may have a stronger effect. Thus, by causing the portion of the one or more transducers to produce second ultrasonic waves in accordance with the calculated liquid saturation, the system is able to operate more efficiently.

[0026] In a general aspect of the invention, a method for clearing a contamination from a surface is provided, themethod comprising: generating first ultrasonic waves coupling the first ultrasonic waves to the surface receiv- ing at least some of the first ultrasonic waves detecting a change in one or more characteristics of a plurality of characteristics of the at least some of the first ultrasonic waves in the; determining a cleaning action for the sur- face from a set of predefined cleaning actions based on the detected change in the one or more characteristics; generating secondultrasonicwaves coupling the second ultrasonic waves to the surface in accordance with the determined cleaning action.

[0027] By coupling the first ultrasonic waves to the surface, the detection of a contamination is facilitated. Detecting a change in one or more characteristics of a plurality of characteristics of the first ultrasonic waves in the received at least some of the first ultrasonic waves allows a cleaning action corresponding to the detected change to be determined and performed. Thus, the cleaning of the surface may be carried out in a better suited manner to the contamination.

[0028] In an aspect of the invention, themethod further comprises: inferring a type of the contamination on the surface from a predefined set of types of contaminations from the detected change in the one or more character- istics; and determining the cleaning action in accordance with the inferred type of the contamination.

[0029] By inferring the type of the contamination, a cleaning action specifically tailored to such a contamina- tion may be determined and performed by coupling sec- ond ultrasonic waves to the surface. For example, differ- ent types of contaminations such as e.g. ice, liquid (e.g. 5 10 15 20 25 30 35 40 45 50 55 6 9 EP 4 725 620 A1 10 droplets) or mud may have different properties (e.g. density, viscosity etc.) whereby different cleaning actions may be beneficial in the removal of such contaminations. It is, thus, beneficial for the cleaning of the surface to infer the type of contamination and base the determination of the cleaning action also on the inferred type of the con- tamination.

[0030] In an aspect of the invention, themethod further comprises: supplying liquid to the surface according to the determined cleaning action.

[0031] Supplying liquid to the surface is particularly beneficial, since some types of contamination may be more efficiently and reliably cleaned thusly. For example, mudmaybemoreeasily removedwhen it is dissolved ina liquid, as the liquid may be propelled by the second ultrasonic waves to the edge of the surface. Additionally, the second ultrasonic waves may be more efficiently coupled to the contamination since the contact are of the contamination to media to which the second ultra- sonic waves have been coupled is enlarged. Further- more, cavitations in the liquid caused by the second ultrasonic wavesmay cause loosening of the contamina- tions from the surface.

[0032] In an aspect of the invention, themethod further comprises: adjusting the power level of the second ultra- sonic waves in accordance with the determined cleaning action, and / or adjusting the pulsing sequence of the second ultrasonic waves in accordance with the deter- mined cleaning action, and / or modulating the second ultrasonic waves in accordance with the determined cleaning action, including modulating at least one of the amplitude, the frequency and the phase shift of the second ultrasonic waves.

[0033] The benefits of such methods are described above in reference to the system according to the inven- tion.

[0034] Other advantages will become apparent from the following description and the above summary is not meant to indicate essential features or limit the scope of the invention. BRIEF DESCRIPTION OF THE FIGURES

[0035] Various aspects and embodiments will be de- scribed with reference to the following figures. It should be appreciated that the figures are not necessarily drawn to scale. Items appearing inmultiple figures are indicated by the same reference number in all the figures in which they appear. Fig. 1 shows an illustrative depiction of a system according to the invention for clearing a contamina- tions from a surface. Fig. 2 shows an illustration of a change in an illus- trative ultrasonic wave due to a contamination on a surface. Fig. 3 shows a storage unit of the system, according to the invention. Fig. 4 shows a liquid supply apparatus configured to supply liquid, preferablywater, to the surfaceaccord- ing to the invention, with an expanded view. Fig. 5 shows an application of liquid, preferably water, to the surface according to the invention, with an expanded view. Fig. 6 shows an exemplary predefined set of types of contaminations according to the invention. Fig. 7 shows pulsed drive signal sequences for the transducers according to the invention. Fig. 8 shows a pulsed drive signal for a transducers according to the invention. Fig. 9 shows amplification schemes for drive signal for transducers according to the invention. Fig. 10 shows a cleaning action according to the invention. Fig. 11 shows a cleaning action according to the invention. Fig. 12 shows a cleaning action according to the invention. Fig. 13 shows a cleaning action according to the invention. Fig. 14 is a schematic illustration of different ultra- sonic wave types. DETAILED DESCRIPTION

[0036] Fig. 1 showsan illustrativedepictionof a system according to the invention for clearing a contamination 140 from a surface 100.

[0037] The system comprises one or more ultrasound transducers 110, 111, 112a-d configured to couple ultra- sonicwaves120,125 to thesurface100.Thesystemalso includes at least one generator 130 configured to gen- erate a drive signal to drive the one or more transducers 110, 111, 112a-d and a receiver 110, 111, 112a-d config- ured to receive at least someof the ultrasonicwaves 120, 125 coupled to the surface 100 by the one or more ultrasound transducers. The oppositely arranged entities 110, 111, 112a-dmay be respective transducer-receiver- pairs. For example, 110 may be one of the transducers and 110 may be the receiver that receives the ultrasonic waves 120, 125 coupled to the surface 110 by the trans- ducer 110.

[0038] The system further includes a control unit 160. 5 10 15 20 25 30 35 40 45 50 55 7 11 EP 4 725 620 A1 12 The control unit 160 is configured to: cause the at least one generator 130 to generate a first drive signal to drive the one or more transducers 110, 111, 112a-d; cause at least one of the oneormore transducers 110, 111, 112a-d to produce first ultrasonic waves 120 in accordance with the first drive signal to couple the first ultrasonic waves 120 to the surface 100; detect a change in one or more characteristics of a plurality of characteristics of at least some of the first ultrasonic waves 120 received by the receiver 110, 111, 112a-d; determinea cleaning action for the surface 100 from a set of predefined cleaning actions based on the detected change in the one or more char- acteristics; cause the at least one generator 130 to gen- erate a second drive signal in accordance with the de- termined cleaning action to drive at least a portion of the one ormore transducers 110, 111, 112a-d; and cause the portionof theoneormore transducers110, 111, 112a-d to producesecondultrasonicwaves125 in accordancewith the second drive signal to couple the second ultrasonic waves 125 to the surface 100.

[0039] The system, e.g. the generator 130, may com- prise a power amplifier 133 configured to amplify the power of the generated first and / or second drive signals.

[0040] The system, e.g. the at least one generator 130, may comprises a pulse generator 135, such that the at least one generator 130 is configured to be able to produce pulsed drive signals, and wherein the control unit 160 is configured to adjust the pulse frequency and pulse duration.

[0041] The generator 130 and the control unit may be hosted by one or more computers 150.

[0042] The system may further include a transceiver 170 configured to detect environmental conditions, wherein the detectable environmental conditions include at least oneof temperature, humidityandair flow,wherein the control unit 160 is configured to receive information conveying the detected environmental conditions and determine the cleaning action based also on the received information.

[0043] The system may further include a liquid supply apparatus 180 configured to supply liquid (185 in Fig. 4), preferably water and / or a cleaning agent, to the surface 100; wherein the control unit 160 is configured to cause the liquid supply apparatus 180 to supply the liquid 185 to the surface100 in accordancewith thedetermined clean- ing action, as illustrated in Figs. 4 and 5 in closer view. The liquid 185 may be a medium that is configured to transfer energy from the surface 100 to the contaminant 140.

[0044] The system of Fig. 1 may be used for clearing a contamination 140 from a surface 100. The system shown in Fig. 1 may for example be used to execute a method for clearing a contamination 140 from a surface 100, the method comprising: generating first ultrasonic waves 120; coupling the first ultrasonic waves 120 to the surface 100; receiving at least some of the first ultrasonic waves 120; detecting a change in one or more charac- teristics of a plurality of characteristics of the at least some of the first ultrasonic waves 120 in the; determining a cleaning action for the surface 100 from a set of pre- defined cleaning actions based on the detected change in the one or more characteristics; generating second ultrasonic waves 125; coupling the second ultrasonic waves 125 to the surface 100 in accordance with the determined cleaning action.

[0045] In other words, an ultrasound surface cleaning systemwith auto-detection and / or autocleaning features is provided.

[0046] For the auto-detection feature, one or more transceivers (piezo material) are sensing environmental condition such as temperature and humidity. This infor- mation is used to update an auto-detection threshold.

[0047] For the auto-detection feature, one of the trans- ducers may be driven at a low power (e.g., below a predetermined threshold value). The opposing transdu- cer operates as a sensor, receiving a signal induced by the vibration along the surface. Surface contaminants change the characteristics of the received signal. Differ- ent contaminant kinds or types (such as rain, ice, mud, condensation and organics) will have different effects on the received signal. By detecting the change of charac- teristics in the received signal, the presence of contami- nant can be detected and the type of contaminant can be distinguished. This can serve as a trigger for activating a cleaning sequence.

[0048] The particular cleaning mode is then triggered that is most relevant to the kind of contaminant. Different cleaning modes, with different cleaning sequence, can include: De-icing, De-fogging, De-condensation, De- mudding, De-dusting, De-matter / protein, and / or De-dro- plets / liquid

[0049] To establish different cleaning modes, ultraso- nic wave parameters are adapted to the kind (type) of contaminant, the parameters including power level, num- ber of operating channels, pulsing sequence, and / or liquid supplier timing.

[0050] Fig. 2 shows an illustration of a change in an illustrative ultrasonicwavedue toa contamination 140on a surface 100.

[0051] The system for clearing the contamination 140 from the surface 100 may be calibrated by recording a base level signal without any contamination on the sur- face 100 between the transducer 110 and receiver 111 (cf. Fig. 2 a)). Variations due to the dimensions of the area, distances between the transducers, etc., can be accounted for in this way in a particularly effective man- ner, if desired.

[0052] Thecontrol unit 160maybeconfigured todetect the change in the one or more characteristics of the at least someof the first ultrasonicwaves 120 by comparing the at least some of the first ultrasonic waves 120 to the base level signal (cf. Fig. 2 b)).

[0053] To remove the contaminant 140 from the sur- face 100, characteristics of the ultrasonicwave120, such as the frequency (cf. Fig. 2 c) indicatingaprolongedpulse duration, dashed line therein indicating half of the pulse 5 10 15 20 25 30 35 40 45 50 55 8 13 EP 4 725 620 A1 14 duration namely from peak to valley of the waveform) and / or waveform, can be changed to perform the deter- mined cleaning action.

[0054] The detected change can be a change in the waveform or frequency characteristics of the at least some of the first ultrasonic waves 120.

[0055] Fig. 3 shows a storage unit of the system for clearing a contamination from a surface.

[0056] The control unit 160 of the system may com- prise a storage unit 165 storing a database 166, wherein the stored database 166 contains associations: between the predefined set of types "cont 1, 2, ..." of contamina- tions 140 (cf. column 1 in database 166) and correspond- ing changes "ch 1, 2,..." (cf. column 2 in database 166) in one or more characteristics of the plurality of character- istics, and between the predefined set of types "cont 1, 2, ..." of contaminations 140 and corresponding cleaning actions "cla 1, 2..." (cf. column 2 in database 166) of the predefined set of cleaning actions.

[0057] As illustrated in Fig. 6, the predefined set of types of contaminations for the surface 100 may com- prise at least one of ice 143 (cf. Fig. 6 c)), fog or con- densation 145 (cf. Fig. 6 e)), mud 142 (cf. Fig. 6 b)), dust 144 (cf. Fig. 6 d)), biological matter (e.g., protein) 142 (cf. Fig. 6b)) and liquid (e.g. droplets) 141 (cf. Fig. 6a)).Other types are also possible. The predefined set of types of contaminations may comprise ice 143 and fog or con- densation 145. Alternatively or additionally, the prede- fined set of types of contaminations may comprise ice 143 and mud 142. Alternatively or additionally, the pre- defined set of types of contaminations may comprise ice 143 and dust 144. Alternatively or additionally, the pre- defined set of types of contaminations may comprise ice 143andbiologicalmatter (e.g., protein) 142.Alternatively or additionally, the predefined set of types of contamina- tions may comprise ice 143 and liquid 141. The prede- fined set of types of contaminations for the surface 100 may comprise ice 143, fog or condensation 145, mud 142, and liquid 141. The predefined set of types of con- taminations for the surface 100 may comprise ice 143, fog or condensation 145, mud 142, dust 144, biological matter (e.g., protein) 142 and liquid 141.

[0058] Returning to Fig. 3, the control unit 160 may be configured to locate the detected change in the one or more characteristics in the database 166 and extract the corresponding type 141, 142, 143, 144, 145 ("cont 1, 2, ...") of the contamination 140 using the association between the change ("ch 1, 2,...") in the one or more characteristics and the corresponding type 141, 142, 143, 144, 145 of the contamination 140, and wherein the control unit 160 is configured to locate the extracted type 141, 142, 143, 144, 145 of the contamination 140 in thedatabase166andextract the corresponding cleaning action ("cla 1, 2,...") using the association between the type 141, 142, 143, 144, 145 of contamination 140 and the corresponding cleaning action.

[0059] Thecontrol unit 160maybeconfigured todetect properties of the contamination 140 (e.g. type of liquid, such as oil or water) based on the detected change in the oneormore characteristics of theat least someof the first ultrasonic waves 120.

[0060] Thecontrol unit 160maybeconfigured todetect properties of individual constituents of the contamination 140 (e.g. the size of an individual droplet, since smaller droplet can more easily evaporate while larger droplets may be moved more easily) based on the detected change in the one or more characteristics of the at least some of the first ultrasonic waves.

[0061] Returning to Fig. 4 and 5, the control unit 160 is configured to cause the liquid supply apparatus 180 to supply the liquid 185 to the surface 100 in accordance with the determined cleaning action. In Fig. 5, the bottom part is a closer view of the dashed rectangle in the upper part of Fig. 5. As shown in the bottom part, the transdu- cers 110, 111, 112a-d may be configured to couple ultra- sonic waves to the liquid 185 through the surface 100 and / or directly to the liquid 185. In the bottom part of Fig. 5, the twowavesectionsshow that thewavesarecoupled eitherdirectly from the transducer into the liquid185or via the surface into the liquid 185.

[0062] Thecontrol unit 160maybe configured to cause the liquid supply apparatus 180 to supply liquid 185 in accordance with the detected contamination 140. The control unit 160 is further configured to: estimate the mass of the contamination 140 based on the detected change in the one or more characteristics, and cause the liquid supply apparatus 180 to supply an amount of liquid 185 in accordance with the determined cleaning action. Thecontrol unit 160maybeconfigured to cause the liquid supply apparatus 180 to supply an amount of liquid 185 approximately equal inmass to theestimatedmassof the contamination 140.

[0063] As illustrated in Figures 1, 7 and 8, the at least one generator 130 comprises a pulse generator 135, such that the at least one generator 130 is configured to produce pulsed drive signals ("Signal of Trans" in Figs. 7 and 8), andwherein the control unit 160 is configured to vary the pulse frequency, pulse duration and / or phase of the pulse from transducer to transducer (cf. Fig. 7) and / or for one and the same transducer over time, as shown in Fig. 8.

[0064] Thecontrol unit 160maybe configured to cause synchronously and / or asynchronously pulsed ultrasonic waves to be produced by different transducers "Trans 1‑4" of the portion of one or more transducers, as shown in Fig. 7.

[0065] For effective droplet propulsion, for example, it may be advisable to avoid droplet cavitation or evapora- tion. This can be achievedby decreasing the power, such as via pulsation. Liquid (e.g, droplets) can be propelled across the surface more quickly if the transducer activa- tion is pulsed.Pulsed transducer actuation can, however, also be beneficial for other types of contamination.

[0066] When assuming that 110, 111, 112a and 112c in Fig. 1 would each be transducers according to the inven- tion and would be transducers ("Trans") 4, 2, 1 and 3 of 5 10 15 20 25 30 35 40 45 50 55 9 15 EP 4 725 620 A1 16 Fig. 7, respectively, then, at the four transducers Trans 1‑4, a propulsion sequence may be executed, at which the left (Trans4)and right (Trans2) transducer arepulsed out of phase while the top (Trans 1) transducer remains activated, as illustrated in Fig. 7.

[0067] In particular, the propulsion sequence may in- clude the following sequences 1, 2, 3, 4 and 5: Propulsion sequence 1 is performed: at which the left (Trans 4) and right (Trans 2) transducer are pulsed ou t of phase while the top (Trans 1) transducer remains acti- vated, as illustrated in Fig. 7. The pulse duration is Xms.

[0068] Propulsion sequence 2 is then performed, at which the left (Trans 4) and right (Trans 2) transducer are pulsed out of phase while the top (Trans 1) transducer remains activated as illustrated in Fig. 7, but the pulse duration is repeatably chirped fromXms to Xms, increas- ing by Xms every cycle.

[0069] Propulsion sequence 3: Frequency Modulated Driving Sequence is performed.

[0070] Propulsion sequence 4: PhaseModulatedDriv- ing Sequence is performed.

[0071] Propulsion sequence 5: Amplitude Modulated Driving Sequence is performed.

[0072] As illustrated in Fig. 9 a), the system’s power amplifier 133 may be configured to amplify the power P for the generated first and / or second drive signals, wherein the power amplifier is configured to be operable in at least two or three different modes, each mode corresponding to a different amount of amplification (gain). In Fig. 9 a) three gain levels are shown: Level high gain (e.g. double the amplification of level normal), normal gain und low gain (e.g. 0.2 times the amplification of the normal gain). The gain for a transducer can be adjusted in steps over time, can be decreased or in- creased continuously over time or may be increased and then reduced again (or vice versa) over time, such as in waves (cf. Fig. 9 a)).

[0073] Thecontrol unit 160maybe configured to cause at least some of the portion of the one or more transdu- cers "Trans 1‑3" to produce ultrasonic waves driven by differently amplified drive signals in accordance with the determined cleaning action. For different transducers, different amplification schemes can thus be applied.

[0074] The control unit 160 may be configured cause the power amplifier 133 to amplify the power of the generated drive signal in accordance with the received information conveying the detected environmental con- ditions.

[0075] Removing of some contaminants, such as ice, may involve activating all transducers at high power. The activation can be continuous or pulsed.

[0076] De-icing, for example,may occur by heating the glass and via shear action of the ice.

[0077] At sub-zero temperatures the piezoelectric ma- terial may be less effective. Therefore, a higher power level is preferred, as shown in Fig. 9 b), when starting the de-icing. As the temperature of the transducer and / or substrate increases, the power level can be reduced, as shown in Fig. 9 b). That is, in the de-ice mode, the transducer can be started in high power mode to warm up the surface and the transducer, and then the power is reduced.

[0078] De-fog mode may involve activating several or all transducers. The activation can be continuous or pulsed. The de-fogging time can be dependent on the power level.

[0079] De-mud / De-matter / protein mode may involve activating several or all transducers at high power with the addition to the surface of a small quantity of amedium configured to transfer energy from the surface to the contaminant. Once the contaminant has been lifted from the surface, a propulsion sequence can be used to move the contaminant off the surface.

[0080] As illustrated inFigs.1, 10, thecontrol unit 160 is configured to choose whether - and preferably also by which amount - the amplitude, frequency and / or phase shift of theultrasonicwave125 ismodulatedbasedon the detected properties of the contamination 140 or proper- ties of the individual constituents of the contamination 140, such as, for example, to force the contamination (e.g. droplet) into motion (rotational and / or translational motion) on the surface 100.

[0081] Fig. 11 illustrates that the one or more transdu- cers 110, 111, 112a-dmay be configured to cause cavita- tions 186 in the supplied liquid 185 for loosening the contaminants 140.

[0082] For example, once amedium, such as the liquid 185, that is configured to transfer energy from the surface 100 to the contaminant 140 is distributed across the surface itmaysurround thecontaminant 140at its bound- ary.Once themedium185hassaturated thecontaminant boundary, ultrasound is activated (cf. Fig. 11 a)). By activating ultrasound 125, the medium penetrates the contaminant through microbubble and microjets created by cavitation effect after a certain amount of time passed (cf. Fig. 6 b)). The medium and ultrasound activation times can be based on the medium’s flow rate and the surface’s size.

[0083] This approachdescribed for Fig. 11 canhavean effect on the nanoscale. For example, contaminants 140 can fill nanostructures at the surface 100, thereby redu- cingcontact angleandcoating efficacyof a coatingon the surface 100. After the medium is released onto the con- taminant 140 and ultrasound is activated, cavitation and microjets clear the contaminant 140 from the nanostruc- tures, so that the contact angle at the surface 100 is enhanced, which, e.g., allows for easy removal of liquid.

[0084] Fig. 12 illustrates that the control unit 160 may be configured to calculate a liquid saturation of a bound- ary of the contamination 140 based on a liquid flow rate of the liquid 185 supplied by the liquid supply apparatus 180, and cause the portion of the one or more transdu- cers 110, 111, 112a-d to produce second ultrasonic waves 125 in accordance with the determined cleaning action and in accordance with the calculated liquid sa- turation. For example, the one or more transducers 5 10 15 20 25 30 35 40 45 50 55 10 17 EP 4 725 620 A1 18 ("Signal") are not switched on until one or more seconds after saturation (cf. Fig. 12 a)) and / or the transducers are allowed to continue running for one or more (e.g. two) seconds after the end of the supply of the liquid 185 (cf. Fig. 12 b)).

[0085] For example, ultrasound may be activated one or more second after full spread of the medium, which is configured to transfer energy from the surface to the contaminant, across the substrate is achieved. The quantity of the medium applied is relative to the contami- nant characteristicsdetected.Ultrasoundcancontinue to be activated for two or more seconds after the medium’s supply ends to enhance proper cleaning.

[0086] Thecontrol unit 160 is configured tocause theat least onegenerator 130 togenerateaseconddrivesignal in accordance with the determined cleaning action to drive at least a portion of the one or more transducers 110, 111, 112a-d.As illustrated inFig. 13,a standingwave may be created in the surface 100 between at least two transducers 110, 111, 112a-d of the portion of the one or more transducers.

[0087] Figure 14 illustrates that the one or more trans- ducers 110, 111, 112a-d may be configured to couple waves of different types to the surface 100. Fig. 14 is a schematic illustration of different wave types.

[0088] The different wave types may comprise at least one of Lamb waves, longitudinal waves, shear waves, and Rayleigh waves. In Fig. 14, the top part a) of the Figure shows a Lamb Wave or Rayleigh Wave. The middle part b) of Fig. 14 showsaquasi-longitudinalwave. The bottom part c) of Fig. 14 shows a shear wave.

[0089] The speed (and hence wavelength) of waves in thesurface100mayvarywith frequency,material proper- ties (for example, Young’s modulus, density, or Poisson ratio), and thickness of the surfacematerial. These para- meters may be known within a certain tolerance or ex- perimentally measured. For example, a laser vibrometer may be used to accurately determine the spatial field of vibration within the surface material during the operation of the system for the purposes of obtaining a more accurate measure of the wave speeds within the surface material for refining and improving the efficiency of the transducer designs.

[0090] Having described several aspects and embodi- ments of the claimed subject-matter, it is to be appre- ciated that various alterations, modifications, and im- provements will readily occur to those skilled in the art. In particular, the present invention can (alternatively) be described by one or more of the following numbered aspects: ASPECTS

[0091] 1. A system for clearing a contamination (140) froma surface (100), the system comprising: one or more ultrasound transducers (110, 111, 112a-d) configured to couple ultrasonic waves (120, 125) to the surface (100); at least one generator (130) configured to gen- erate a drive signal to drive the one or more transducers (110, 111, 112a-d); a receiver (110, 111, 112a-d) configured to re- ceive at least someof the ultrasonicwaves (120, 125) coupled to the surface (100); and a control unit (160); wherein the control unit (160) is configured to: cause the at least one generator (130) to gen- erate a first drive signal to drive the one or more transducers (110, 111, 112a-d); cause at least one of the one or more transdu- cers (110, 111, 112a-d) toproducefirst ultrasonic waves (120) in accordance with the first drive signal to couple the first ultrasonic waves (120) to the surface (100); detect a change inoneormore characteristics of a plurality of characteristics of at least some of the first ultrasonic waves (120) received by the receiver (110, 111, 112a-d); determineacleaningaction for the surface (100) from a set of predefined cleaning actions based on the detected change in the one or more characteristics; cause the at least one generator (130) to gen- erate a second drive signal in accordance with the determined cleaning action to drive at least a portion of the oneormore transducers (110, 111, 112a-d); and cause theportionof theoneormore transducers (110, 111, 112a-d) to produce second ultrasonic waves (125) in accordance with the second drive signal to couple the second ultrasonic waves (125) to the surface (100). 2. The system of aspect 1, wherein the control unit (160) is further configured to infer a type (141, 142, 143, 144, 145) of the contamination (140) on the surface (100) from a predefined set of types of con- taminations from the detected change in the one or more characteristics of the at least some of the first ultrasonic waves (120), and wherein the determined cleaning action corresponds to the inferred type (141, 142, 143, 144, 145) of the contamination (140). 3. The system of any one of the preceding aspects, wherein the control unit (160) is configured to detect the change in the one or more characteristics of the at least some of the first ultrasonic waves (120) by comparing the at least some of the first ultrasonic waves (120) to a base level signal. 4. The system of any one of the preceding aspects, 5 10 15 20 25 30 35 40 45 50 55 11 19 EP 4 725 620 A1 20 wherein the detected change is a change in the waveform or frequency characteristics of the at least some of the first ultrasonic waves (120). 5. The system of any one of the preceding aspects, wherein the detected change is at least one of the power level, the frequency spectrum and the ampli- tude of the ultrasonic detection waves. 6. The system of any one of the preceding aspects, wherein the one or more transducers (110, 111, 112a-d) comprise at least two transducers (110, 111, 112a-d), and wherein oneof theat least two transducers (110, 111, 112a-d) functions as the receiver (110, 111, 112a-d). 7. The system of any of the preceding aspects, wherein the control unit (160) is configured to as- sess, whether the detected change in the one or more characteristics crossesa threshold value, such that the cleaning action to be performed is only determined and / or performed when the detected change in the one or more characteristics crosses the threshold value. 8. The system of aspect 7, further comprising: a transceiver (170) configured to detect envir- onmental conditions, wherein the detectable environmental condi- tions include at least one of temperature, hu- midity and air flow, wherein the control unit (160) is configured to receive information conveying the detected en- vironmental conditionsanddetermine theclean- ing action based also on the received informa- tion. 9. The system of aspect 8 wherein the control unit (160) is configured toadapt the threshold value to the environmental conditions based on the received in- formation. 10. The system of any one of aspects 2 to 9, wherein the control unit (160) comprises a storage unit (165) storing a database (166), wherein the stored data- base (166) contains associations: between the predefined set of types of contam- ination (140)s and corresponding changes in one or more characteristics of the plurality of characteristics, and between the predefined set of types of contam- ination (140)s and corresponding cleaning ac- tions of the predefined set of cleaning actions, wherein the control unit (160) is configured to locate the detected change in the one or more characteristics in thedatabase (166) andextract the corresponding type (141, 142, 143, 144, 145) of the contamination (140) using the asso- ciation between the change in the one or more characteristics and the corresponding type (141, 142, 143, 144, 145) of the contamination (140), and wherein the control unit (160) is configured to locate the extracted type (141, 142, 143, 144, 145) of the contamination (140) in the database (166) and extract the corresponding cleaning action using the association between the type (141, 142, 143, 144, 145) of contamination (140) and the corresponding cleaning action. 11. The system of any one of the preceding aspects, further comprising: a liquid supply apparatus (180) configured to supply liquid (185), preferably water, to the sur- face (100); wherein the control unit (160) is configured to cause the liquid supply apparatus (180) to sup- ply liquid (185) to the surface (100) in accor- dance with the determined cleaning action. 12. The system of aspect 11, wherein the transdu- cers (110, 111, 112a-d) are configured to couple ultrasonic waves to the liquid (185) through the sur- face (100) and / or directly. 13. The system of any one of aspects 11 and 12, wherein the control unit (160) is configured to cause the liquid supply apparatus (180) to supply liquid (185) in accordancewith the detected contamination (140). 14. The systemof aspect 13, wherein the control unit (160) is further configured to: estimate the mass of the contamination (140) basedon thedetectedchange in theoneormore characteristics, and cause the liquid supply apparatus (180) to sup- ply an amount of liquid (185) in accordance with the determined cleaning action. 15. The system of any one of aspects 13 or 14, wherein the control unit (160) is configured to cause the liquid supply apparatus (180) to supply an amount of liquid (185) approximately equal in mass to the estimated mass of the contamination (140). 16. The system of any of one of aspects 2 to 15, wherein the predefined set of types of contamina- tions comprises at least one of ice (143), fog / con- densation (145), mud (142), dust (144), biological matter (142) and liquid (141). 5 10 15 20 25 30 35 40 45 50 55 12 21 EP 4 725 620 A1 22 17. The system of any of the preceding aspects, wherein the control unit (160) is configured to detect properties of the contamination (140) based on the detectedchange in theoneormorecharacteristicsof the at least some of the first ultrasonic waves (120). 18. The system of any of the preceding aspects, wherein the control unit (160) is configured to detect properties of individual constituents of the contam- ination (140) based on the detected change in the oneormorecharacteristicsof theat least someof the first ultrasonic waves (120). 19. The system of any of the preceding aspects, wherein the system comprises a power amplifier (133) configured to amplify the power of the gener- ated first and / or second drive signals. 20. The system of aspect 19, wherein the power amplifier (133) is configured to beoperable in at least two different modes, each mode corresponding to a different amount of amplification. 21. The systemof aspect 20, wherein the control unit (160) is configured to cause at least some of the portion of the one or more transducers (110, 111, 112a-d) to produce ultrasonic waves driven by dif- ferently amplified drive signals in accordance with the determined cleaning action. 22. The system of any of the preceding aspects, wherein the at least one generator (130) comprises a pulse generator (135), such that the at least one generator (130) is configured to be able to produce pulsed drive signals, and wherein the control unit (160) is configured to adjust the pulse frequency and pulse duration. 23. The systemof aspect 22, wherein the control unit (160) is configured to cause synchronously and / or asynchronously pulsed ultrasonic waves to be pro- duced by different transducers (110, 111, 112a-d) of the portion of one or more transducers (110, 111, 112a-d). 24. The system of any of the preceding aspects, wherein the control unit (160) is configured to cause the at least one generator (130) to modulate the second drive signal in accordance with the deter- mined cleaning action, wherein at least one of the amplitude, the frequency and the phase shift of the second drive signal is modulated. 25. The system of aspect 24, wherein control unit (160) is configured to choosewhether the amplitude, frequency or phase shift is modulated based on the detected properties of the contamination (140) or properties of the individual constituents of the con- tamination (140). 26. The system of any one of aspects 19 to 25, wherein the control unit (160) is configured cause the power amplifier (133) to amplify the power of the generated drive signal in accordance with the re- ceived information conveying the detected environ- mental conditions. 27.Thesystemofaspect anyoneof aspects 11 to26, wherein the transducers (110, 111, 112a-d) are con- figured to cause cavitations (186) in the supplied liquid (185) for loosening the contaminants. 28. The system of any one of aspects 11 to 27, wherein the control unit (160) is configured to calcu- late a liquid saturation of a boundary of the contam- ination (140) based on a liquid flow rate of the liquid (185) supplied by the liquid supply apparatus (180), and cause the portion of the one or more transducers (110, 111, 112a-d) to produce second ultrasonic waves (125) in accordance with the determined cleaning action and in accordance with the calcu- lated liquid saturation. 29. The system of any one of aspects 11 to 28, wherein the liquid (185) contains a cleaning agent. 30. The system of aspect 29, wherein the liquid supply apparatus (180) is configured to add the cleaning agent to the liquid (185), and wherein the control unit (160) is configured to cause thecleaningapparatus tomix the liquid (185)with the cleaning agent at a ratio in accordance with the determined cleaning action. 31. The system of any one of the preceding aspects, wherein a standing wave is created in the surface (100) between at least two transducers (110, 111, 112a-d) of the portion of the one ormore transducers (110, 111, 112a-d). 32. The system of any one of the preceding aspects, wherein the transducers (110, 111, 112a-d) are con- figured to couple waves of different types to the surface (100). 33. The system of aspect 32, wherein the different wave types comprise at least one of Lamb waves, shear waves, and Rayleigh waves. 34. Amethod for clearing a contamination (140) from a surface (100), the method comprising: generating first ultrasonic waves (120); coupling the first ultrasonic waves (120) to the surface (100); 5 10 15 20 25 30 35 40 45 50 55 13 23 EP 4 725 620 A1 24 receiving at least some of the first ultrasonic waves (120); detecting a change in one or more characteris- tics of a plurality of characteristics of the at least some of the first ultrasonic waves (120) in the; determining a cleaning action for the surface (100) from a set of predefined cleaning actions basedon thedetectedchange in theoneormore characteristics; generating second ultrasonic waves (125); coupling the second ultrasonic waves (125) to the surface (100) in accordance with the deter- mined cleaning action. 35. The method of aspect 34, further comprising: inferring a type (141, 142, 143, 144, 145) of the contamination (140) on the surface (100) from a predefined set of types of contaminations from the detected change in the one or more char- acteristics; and determining the cleaning action in accordance with the inferred type (141, 142, 143, 144, 145) of the contamination (140). 36. The method of any one of aspects 34 and 35, further comprising: detecting the change in the one or more character- istics of the received at least some of the first ultra- sonicwaves (120)bycomparing the receivedat least some of the first ultrasonic waves (120) to a base level signal. 37. The method of any one of aspects 34 to 36, further comprising: assessing, whether the detected change in the one or more characteristics crosses a threshold value; and determining the cleaning action and / or coupling the ultrasonic cleaning waves to the surface (100) in accordance with the determined clean- ing action only when the detected change in the one or more characteristics crosses the thresh- old value. 38. The method of aspect 37, further comprising: receiving information conveying detected envir- onmental conditions; and determining the cleaning action based also on the received information. 39. The method of aspect 38, further comprising: adapting the threshold value to the environmental conditions in accordance with the received informa- tion. 40. The method of any one of aspects 34 to 39, further comprising: supplying liquid (185) to the surface (100) according to the determined cleaning action. 41. The method of any one of aspects 34 to 40, further comprising: detecting properties of the contamination (140) based on the detected change in the one or more characteristics of the at least some of the first ultra- sonic waves (120). 42. The method of any one of aspects 34 to 41, further comprising: detecting properties of individual constituents of the contamination (140) based on the detected change in theoneormore characteristicsof theat least some of the first ultrasonic waves (120). 43. The method of any one of aspects 34 to 42, further comprising: adjusting the power level of the second ultrasonic waves (125) in accordance with the determined cleaning action. 44. The method of any one of aspects 34 to 43, further comprising: adjusting the pulsing sequence of the second ultra- sonic waves (125) in accordance with the deter- mined cleaning action. 45. The method of any one of aspects 34 to 44, further comprising: modulating the second ultrasonic waves (125) in accordance with the determined cleaning action, including modulating at least one of the amplitude, the frequency and the phase shift of the second ultrasonic waves (125). 46. The method of aspect 45, further comprising: modulating the second ultrasonic waves (125) based on the detected properties of the contamina- tion (140) or properties of the individual constituents of the contamination (140). 47. The method of any one of aspects 40 to 46, further comprising: calculating a liquid saturation of a boundary of the contamination (140) based on a liquid flow rate of the supplied liquid (185), and coupling the second ultrasonic waves (125) to the surface (100) in accordance with the deter- mined cleaning action and in accordance with the calculated liquid saturation. 48. The method of any one of aspects 34 to 47, further comprising: 5 10 15 20 25 30 35 40 45 50 55 14 25 EP 4 725 620 A1 26 creating a standing wave in the surface (100). 49.Useof thesystemofanyoneof aspects1 to33 for clearing a contamination (140) from a surface (100).

[0092] Further, though advantages of the present in- vention are indicated, it should be appreciated that not every embodiment of the invention described herein will include every described advantage. Some aspects and embodimentsmaynot implement any features described as advantageous herein and in some instances one or more of the described features may be implemented to achieve further embodiments. Accordingly, this descrip- tion and these drawings are by way of example only.

[0093] Having described several aspects and embodi- ments of this invention, it is to be appreciated that various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, mod- ifications, and improvements are intended to be part of this invention, and are intended to be within the scope of the invention as defined by the appended claims.

[0094] The various aspects and embodiments de- scribed above can be combined to provide yet further embodiments. These and other changes can bemade to the embodiments in light of the abovedetailed descrip- tion. In general, in the following claims, the terms used should not be construed to limit the claims to the specific aspects and embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Claims 1. A system for clearing a contamination froma surface (100), the system comprising: one or more ultrasound transducers (110, 111, 112a-d) configured to couple ultrasonic waves (120, 125) to the surface (100); at least one generator (130) configured to gen- erate a drive signal to drive the one or more transducers (110, 111, 112a-d); a receiver (110, 111, 112a-d) configured to re- ceive at least someof the ultrasonicwaves (120, 125) coupled to the surface (100); and a control unit (160); wherein the control unit (160) is configured to: cause the at least one generator (130) to gen- erate a first drive signal to drive the one or more transducers (110, 111, 112a-d); cause at least one of the one or more transdu- cers (110, 111, 112a-d) toproducefirst ultrasonic waves (120) in accordance with the first drive signal to couple the first ultrasonic waves (120) to the surface (100); detect a change inoneormore characteristics of a plurality of characteristics of at least some of the first ultrasonic waves (120) received by the receiver (110, 111, 112a-d); determineacleaningaction for the surface (100) from a set of predefined cleaning actions based on the detected change in the one or more characteristics; cause the at least one generator (130) to gen- erate a second drive signal in accordance with the determined cleaning action to drive at least a portion of the oneormore transducers (110, 111, 112a-d); and cause theportionof theoneormore transducers (110, 111, 112a-d) to produce second ultrasonic waves (125) in accordance with the second drive signal to couple the second ultrasonic waves (125) to the surface (100). 2. The system of claim 1, wherein the control unit (160) is further configured to infer a type (141, 142, 143, 144, 145) of the contamination (140) on the surface (100) from a predefined set of types of contamina- tions from the detected change in the one or more characteristics of the at least some of the first ultra- sonic waves (120), and wherein the determined cleaning action corresponds to the inferred type (141, 142, 143, 144, 145) of the contamination (140), wherein the predefined set of types of con- taminations comprises at least one of ice (143), fog / condensation (145), mud (142), dust (144), bio- logical matter (142) and liquid (141). 3. The system of any one of the preceding claims, wherein the control unit (160) is configured to detect the change in the one or more characteristics of the at least some of the first ultrasonic waves (120) by comparing the at least some of the first ultrasonic waves (120) to a base level signal, and / or wherein the detected change is a change in the waveform and / or frequency characteristics of the at least some of the first ultrasonic waves (120), wherein, prefer- ably, the detected change is at least one of the power level, the frequency spectrum and / or the amplitude of the ultrasonic detection waves. 4. The system of any one of the preceding claims, wherein the one or more transducers (110, 111, 112a-d) comprise at least two transducers (110, 111, 112a-d), and wherein one of the at least two transducers (110, 111, 112a-d) functions as the re- ceiver (110, 111, 112a-d). 5. The system of any of the preceding claims, wherein the control unit (160) is configured to assess, whether the detected change in the one or more characteristics crosses a threshold value, such that 5 10 15 20 25 30 35 40 45 50 55 15 27 EP 4 725 620 A1 28 the cleaning action to be performed is only deter- mined and / or performed when the detected change in theoneormorecharacteristics crosses the thresh- old value, wherein the system preferably further comprises: a transceiver (170) configured to detect environmen- tal conditions, wherein the detectable environmental conditions include at least one of temperature, hu- midity and air flow, wherein the control unit (160) is configured to receive information conveying the de- tected environmental conditions and determine the cleaning action based also on the received informa- tion, andwherein, preferably, the control unit (160) is configured to adapt the threshold value to the en- vironmental conditions based on the received infor- mation. 6. The system of any one of the preceding claims, further comprising: a liquid supply apparatus (180) configured to supply liquid (185), preferably water, to the surface (100); wherein the control unit (160) is configured to cause the liquid supply apparatus (180) to supply liquid (185) to the surface (100) in accordance with the determined cleaning action, preferably wherein the transducers (110, 111, 112a-d) are configured to couple ultrasonic waves to the liquid (185) through the surface (100) and / or directly, and / or wherein the control unit (160) is configured to cause the liquid supply apparatus (180) to supply liquid (185) in accordance with the detected contamination (140). 7. The system of any of the preceding claims, wherein the system comprises a power amplifier (133) con- figured to amplify the power of the generated first and / or second drive signals; wherein the power am- plifier (133) is configured to be operable in at least two different modes, each mode corresponding to a different amount of amplification; wherein the control unit (160) is configured to cause at least some of the portion of the one or more transducers (110, 111, 112a-d) to produce ultrasonic waves driven by dif- ferently amplified drive signals in accordance with the determined cleaning action. 8. The system of any of the preceding claims, wherein the at least one generator (130) comprises a pulse generator (135), such that the at least one generator (130) is configured tobeable to producepulseddrive signals, and wherein the control unit (160) is config- ured to adjust the pulse frequency and pulse dura- tion, preferably wherein the control unit (160) is configured tocausesynchronouslyand / orasynchro- nously pulsed ultrasonic waves to be produced by different transducers (110, 111, 112a-d) of theportion of one or more transducers (110, 111, 112a-d). 9. The system of any of the preceding claims, wherein the control unit (160) is configured to cause the at least one generator (130) to modulate the second drive signal in accordance with the determined cleaning action, wherein at least one of the ampli- tude, the frequency and thephase shift of the second drive signal is modulated. 10. The system of any one of claims 6 to 9, wherein the control unit (160) is configured to calculate a liquid saturation of a boundary of the contamination (140) based on a liquid flow rate of the liquid (185) supplied by the liquid supply apparatus (180), and cause the portion of the one or more transducers (110, 111, 112a-d) to produce second ultrasonic waves (125) in accordance with the determined cleaning action and in accordance with the calcu- lated liquid saturation. 11. A method for clearing a contamination (140) from a surface (100), the method comprising: generating first ultrasonic waves (120); coupling the first ultrasonic waves (120) to the surface (100); receiving at least some of the first ultrasonic waves (120); detecting a change in one or more characteris- tics of a plurality of characteristics of the at least some of the first ultrasonic waves (120) in the; determining a cleaning action for the surface (100) from a set of predefined cleaning actions basedon thedetectedchange in theoneormore characteristics; generating second ultrasonic waves (125); and coupling the second ultrasonic waves (125) to the surface (100) in accordance with the deter- mined cleaning action. 12. The method of claim 11, further comprising: inferring a type (141, 142, 143, 144, 145) of the contamination (140) on the surface (100) from a predefined set of types of contaminations from the detected change in the one or more char- acteristics; and determining the cleaning action in accordance with the inferred type (141, 142, 143, 144, 145) of the contamination (140). 13. The method of any one of claims 11 to 12, further comprising: supplying liquid (185) to the surface (100) according to the determined cleaning action. 14. The method of any one of claims 11 to 13, further comprising: adjusting the power level of the second ultra- sonic waves (125) in accordance with the de- 5 10 15 20 25 30 35 40 45 50 55 16 29 EP 4 725 620 A1 30 termined cleaning action, and / or adjusting the pulsing sequence of the second ultrasonic waves (125) in accordance with the determined cleaning action, and / or modulating the secondultrasonicwaves (125) in accordance with the determined cleaning ac- tion, including modulating at least one of the amplitude, the frequency and the phase shift of the second ultrasonic waves (125). 15. Use of the system of any one of claims 1 to 10 for clearing a contamination (140) from a surface (100). 5 10 15 20 25 30 35 40 45 50 55 17 EP 4 725 620 A1 18 EP 4 725 620 A1 19 EP 4 725 620 A1 20 EP 4 725 620 A1 21 EP 4 725 620 A1 22 EP 4 725 620 A1 23 EP 4 725 620 A1 5 10 15 20 25 30 35 40 45 50 55 24 EP 4 725 620 A1 5 10 15 20 25 30 35 40 45 50 55 摘要 描述了用于表面的超声清洁的系统、相应的方法以及该系统用于清洁表面的用途。用 于清洁来自表面的污染物的方法包括：产生第一超声波；将第一超声波耦合到表面； 接收至少一些第一超声波；检测至少一些第一超声波的多个特征中的一个或多个特征 的变化；基于检测到的一个或多个特征的变化，从一组预定义的清洁动作中确定用于 表面的清洁动作；产生第二超声波；以及根据确定的清洁动作将第二超声波耦合到表 面。

Claims

1. A system for clearing a contamination from a surface (100), the system comprising: one or more ultrasound transducers (110, 111, 112a-d) configured to couple ultrasonic waves (120, 125) to the surface (100); at least one generator (130) configured to generate a drive signal to drive the one or more transducers (110, 111, 112a-d); a receiver (110, 111, 112a-d) configured to receive at least some of the ultrasonic waves (120, 125) coupled to the surface (100); and a control unit (160); wherein the control unit (160) is configured to: cause the at least one generator (130) to generate a first drive signal to drive the one or more transducers (110, 111, 112a-d); cause at least one of the one or more transducers (110, 111, 112a-d) to produce first ultrasonic waves (120) in accordance with the first drive signal to couple the first ultrasonic waves (120) to the surface (100); detect a change in one or more characteristics of a plurality of characteristics of at least some of the first ultrasonic waves (120) received by the receiver (110, 111, 112a-d); determine a cleaning action for the surface (100) from a set of predefined cleaning actions based on the detected change in the one or more characteristics; cause the at least one generator (130) to generate a second drive signal in accordance with the determined cleaning action to drive at least a portion of the one or more transducers (110, 111, 112a-d); and cause the portion of the one or more transducers (110, 111, 112a-d) to produce second ultrasonic waves (125) in accordance with the second drive signal to couple the second ultrasonic waves (125) to the surface (100).

2. The system of claim 1, wherein the control unit (160) is further configured to infer a type (141, 142, 143, 144, 145) of the contamination (140) on the surface (100) from a predefined set of types of contaminations from the detected change in the one or more characteristics of the at least some of the first ultrasonic waves (120), and wherein the determined cleaning action corresponds to the inferred type (141, 142, 143, 144, 145) of the contamination (140), wherein the predefined set of types of contaminations comprises at least one of ice (143), fog / condensation (145), mud (142), dust (144), biological matter (142) and liquid (141).

3. The system of any one of the preceding claims, wherein the control unit (160) is configured to detect the change in the one or more characteristics of the at least some of the first ultrasonic waves (120) by comparing the at least some of the first ultrasonic waves (120) to a base level signal, and / or wherein the detected change is a change in the waveform and / or frequency characteristics of the at least some of the first ultrasonic waves (120), wherein, preferably, the detected change is at least one of the power level, the frequency spectrum and / or the amplitude of the ultrasonic detection waves.

4. The system of any one of the preceding claims, wherein the one or more transducers (110, 111, 112a-d) comprise at least two transducers (110, 111, 112a-d), and wherein one of the at least two transducers (110, 111, 112a-d) functions as the receiver (110, 111, 112a-d).

5. The system of any of the preceding claims, wherein the control unit (160) is configured to assess, whether the detected change in the one or more characteristics crosses a threshold value, such that the cleaning action to be performed is only determined and / or performed when the detected change in the one or more characteristics crosses the threshold value, wherein the system preferably further comprises: a transceiver (170) configured to detect environmental conditions, wherein the detectable environmental conditions include at least one of temperature, humidity and air flow, wherein the control unit (160) is configured to receive information conveying the detected environmental conditions and determine the cleaning action based also on the received information, and wherein, preferably, the control unit (160) is configured to adapt the threshold value to the environmental conditions based on the received information.

6. The system of any one of the preceding claims, further comprising: a liquid supply apparatus (180) configured to supply liquid (185), preferably water, to the surface (100); wherein the control unit (160) is configured to cause the liquid supply apparatus (180) to supply liquid (185) to the surface (100) in accordance with the determined cleaning action, preferably wherein the transducers (110, 111, 112a-d) are configured to couple ultrasonic waves to the liquid (185) through the surface (100) and / or directly, and / or wherein the control unit (160) is configured to cause the liquid supply apparatus (180) to supply liquid (185) in accordance with the detected contamination (140).

7. The system of any of the preceding claims, wherein the system comprises a power amplifier (133) configured to amplify the power of the generated first and / or second drive signals; wherein the power amplifier (133) is configured to be operable in at least two different modes, each mode corresponding to a different amount of amplification; wherein the control unit (160) is configured to cause at least some of the portion of the one or more transducers (110, 111, 112a-d) to produce ultrasonic waves driven by differently amplified drive signals in accordance with the determined cleaning action.

8. The system of any of the preceding claims, wherein the at least one generator (130) comprises a pulse generator (135), such that the at least one generator (130) is configured to be able to produce pulsed drive signals, and wherein the control unit (160) is configured to adjust the pulse frequency and pulse duration, preferably wherein the control unit (160) is configured to cause synchronously and / or asynchronously pulsed ultrasonic waves to be produced by different transducers (110, 111, 112a-d) of the portion of one or more transducers (110, 111, 112a-d).

9. The system of any of the preceding claims, wherein the control unit (160) is configured to cause the at least one generator (130) to modulate the second drive signal in accordance with the determined cleaning action, wherein at least one of the amplitude, the frequency and the phase shift of the second drive signal is modulated.

10. The system of any one of claims 6 to 9, wherein the control unit (160) is configured to calculate a liquid saturation of a boundary of the contamination (140) based on a liquid flow rate of the liquid (185) supplied by the liquid supply apparatus (180), and cause the portion of the one or more transducers (110, 111, 112a-d) to produce second ultrasonic waves (125) in accordance with the determined cleaning action and in accordance with the calculated liquid saturation.

11. A method for clearing a contamination (140) from a surface (100), the method comprising: generating first ultrasonic waves (120); coupling the first ultrasonic waves (120) to the surface (100); receiving at least some of the first ultrasonic waves (120); detecting a change in one or more characteristics of a plurality of characteristics of the at least some of the first ultrasonic waves (120) in the; determining a cleaning action for the surface (100) from a set of predefined cleaning actions based on the detected change in the one or more characteristics; generating second ultrasonic waves (125); and coupling the second ultrasonic waves (125) to the surface (100) in accordance with the determined cleaning action.

12. The method of claim 11, further comprising: inferring a type (141, 142, 143, 144, 145) of the contamination (140) on the surface (100) from a predefined set of types of contaminations from the detected change in the one or more characteristics; and determining the cleaning action in accordance with the inferred type (141, 142, 143, 144, 145) of the contamination (140).

13. The method of any one of claims 11 to 12, further comprising: supplying liquid (185) to the surface (100) according to the determined cleaning action.

14. The method of any one of claims 11 to 13, further comprising: adjusting the power level of the second ultrasonic waves (125) in accordance with the determined cleaning action, and / or adjusting the pulsing sequence of the second ultrasonic waves (125) in accordance with the determined cleaning action, and / or modulating the second ultrasonic waves (125) in accordance with the determined cleaning action, including modulating at least one of the amplitude, the frequency and the phase shift of the second ultrasonic waves (125).

15. Use of the system of any one of claims 1 to 10 for clearing a contamination (140) from a surface (100).

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