Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
  • G02B27/0006—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 with means to keep optical surfaces clean, e.g. by preventing or removing dirt, stains, contamination, condensation
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B08—CLEANING
  • B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
  • B08B7/00—Cleaning by methods not provided for in a single other subclass or a single group in this subclass
  • B08B7/02—Cleaning by methods not provided for in a single other subclass or a single group in this subclass by distortion, beating, or vibration of the surface to be cleaned
  • B08B7/026—Using sound waves
  • B08B7/028—Using ultrasounds
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60S—SERVICING, CLEANING, REPAIRING, SUPPORTING, LIFTING, OR MANOEUVRING OF VEHICLES, NOT OTHERWISE PROVIDED FOR
  • B60S1/00—Cleaning of vehicles
  • B60S1/02—Cleaning windscreens, windows or optical devices
  • B60S1/56—Cleaning windscreens, windows or optical devices specially adapted for cleaning other parts or devices than front windows or windscreens
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
  • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
  • G01S7/481—Constructional features, e.g. arrangements of optical elements
  • G01S7/4811—Constructional features, e.g. arrangements of optical elements common to transmitter and receiver
  • G01S7/4813—Housing arrangements
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
  • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
  • G01S7/497—Means for monitoring or calibrating
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60S—SERVICING, CLEANING, REPAIRING, SUPPORTING, LIFTING, OR MANOEUVRING OF VEHICLES, NOT OTHERWISE PROVIDED FOR
  • B60S1/00—Cleaning of vehicles
  • B60S1/02—Cleaning windscreens, windows or optical devices
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
  • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
  • G01S7/497—Means for monitoring or calibrating
  • G01S2007/4975—Means for monitoring or calibrating of sensor obstruction by, e.g. dirt- or ice-coating, e.g. by reflection measurement on front-screen
  • G01S2007/4977—Means for monitoring or calibrating of sensor obstruction by, e.g. dirt- or ice-coating, e.g. by reflection measurement on front-screen including means to prevent or remove the obstruction

Definitions

• the present invention relates to a device for cleaning a body in contact with an optical surface by means of ultrasonic waves.
• EWOD Electro Wetting On Devices
• autonomous motor vehicles include a large number of sensors in order to determine the distances and speeds of other vehicles present on the road.
• sensors for example lidars
• lidars are also subject to bad weather and splashes of mud and require frequent cleaning.
• a windshield wiper is unsuitable for cleaning a small area of such a sensor.
• US 2016/0170203 Al describes a device for cleaning a camera mounted on a vehicle by means of ultrasonic waves.
• the invention aims to satisfy this need and proposes a device comprising:
• an optical surface cleaning unit comprising at least one wave transducer acoustically coupled with the optical surface, the wave transducer comprising a piezoelectric layer and electrodes of opposite polarity in contact with the piezoelectric layer, and being configured to generating at least one surface ultrasonic wave or a Lamb wave propagating in the optical surface,
• the device comprising a device configured to capture and/or emit radiation through the region of optical interest.
• the device according to the invention thus makes it possible to effectively clean the optical surface by means of the propagation of the surface ultrasonic wave, so that a body, for example a drop of rain, in contact with the optical surface does not does not prevent effective transmission of radiation through the optical surface.
• layer is usually meant a uniform extent applied or deposited on a surface.
• the transducer is placed outside the optical field of the device. This limits the potential shading effects that the transducer can cause on the device.
• the uptake and/or emission of radiation through the optical surface is optimized.
• optical field we consider the portion of space in the direction of which the device is capable of emitting radiation and/or from which it is capable of capturing radiation.
• the radiation may be light radiation in the visible and/or in the infrared and/or in the ultraviolet.
• the device may include a processing unit configured to analyze among all of the radiation captured by the device, only the part having crossed the optical region of interest.
• a processing unit configured to analyze among all of the radiation captured by the device, only the part having crossed the optical region of interest.
• such an analysis unit is suitable in a variant in which all or part of the transducer is contained in the optical field of the device.
• the transducer is placed on the periphery of the optical surface.
• the transducer in addition to its low interaction with the operation of the device, the transducer can thus be easily protected, for example by a support carrying the optical surface.
• the wave transducer extends from an edge of the optical surface over a distance of less than 10%, or even less than 5% of the length of the optical surface.
• length of the optical surface is meant the distance separating two opposite edges of the optical surface along one side of the optical surface.
• the transducer extends from an edge of the optical surface over a distance of less than 30 mm, preferably less than 20 mm, preferably less than 10 mm.
• the transducer is preferably in contact with the optical surface.
• the transducer can be attached to the optical surface in various ways.
• the transducer can be in the form of a foil which is transferred onto the optical surface.
• foil is meant a flexible and thin film, in particular having a thickness of less than 100 ⁇ m.
• the transducer can be fixed by molecular adhesion, or by means of a thin metallic layer providing adhesion between the optical surface and the piezoelectric layer.
• the layer can be made of a metal or an alloy with a low melting temperature, i.e. having a melting temperature of less than 200° C., for example an indium alloy.
• the metallic layer can be made of a metal or of an alloy having a melting temperature greater than 200° C., for example of an aluminum and/or gold alloy.
• the transducer can be fixed on the optical surface by means of a method comprising a step of melting a portion of the piezoelectric layer and/or of a portion of the optical surface followed by a step consisting in compressing together the piezoelectric layer and the optical surface, the respective molten portions of the optical surface and of the piezoelectric layer being in contact with one of the other.
• the transducer can be fixed on the optical surface by means of a process comprising the deposition of bonding layers of an alloy with a low melting temperature on a portion of the transducer and on a portion of the optical surface respectively, at least partially melting said bonding layers, then compressing the piezoelectric layer and the optical surface, the faces of the bonding layers opposite the optical surface and the piezoelectric layer being brought into contact with each other during compression.
• the bonding layers can be deposited by sputtering, or by an evaporation technique implemented in the field of the deposition of thin layers.
• the transducer may be disposed between the optical surface and the device.
• the transducer can be protected by the optical surface from bad weather and/or splashes.
• the transducer is then shaped to generate a Lamb wave so as to reach the face, opposite the device and in contact with which a body, for example a drop of rain, can be deposited.
• the optical surface may be disposed between the transducer and the device.
• the transducer is then in contact with the face of the optical surface opposite the device. It can be configured to emit an ultrasonic surface wave propagating on this face.
• the device may include a cover superimposed on the transducer and shaped to define a housing for protecting the transducer.
• the piezoelectric layer has the shape of a strip which extends over one face of the optical surface.
• the strip extends along and preferably parallel to an edge of the optical surface.
• the piezoelectric layer can form a frame surrounding at least partially, in particular entirely, the optical region of interest.
• the outer contour and/or the inner contour of the frame can be homothetic to the contour of the face of the optical surface on which the piezoelectric layer is arranged.
• the thickness of the piezoelectric layer can be chosen according to the wavelength ⁇ of the ultrasonic surface wave.
• the thickness of the piezoelectric layer is less than or equal to 5*A, preferably less than or equal to 1.5*A, of preferably less than or equal to A, or even less than or equal to 0.5* ⁇ , in particular for a frequency of the surface ultrasonic wave being between 0.1 MHz and 60 MHz.
• the piezoelectric layer can have a thickness of between 1 ⁇ m and 300 ⁇ m. It may have a thickness less than or equal to 100 ⁇ m, less than 50 ⁇ m, or even less than 10 ⁇ m.
• the ratio of the thickness of the optical surface to the thickness of the piezoelectric layer is preferably greater than 2, preferably greater than 10, or even greater than 50.
• It can be deposited on the optical surface by a method chosen from physical vapor deposition, chemical vapor deposition, magnetron sputtering and electron cyclotron resonance.
• the piezoelectric layer can be made of a material chosen from the group formed by lithium niobate, aluminum nitride, zinc oxide, lead titano-zircanate, and mixtures thereof.
• the piezoelectric layer may be opaque to light. Alternatively, it may be transparent.
• transparent is meant a transparency to light radiation in the visible and/or to radiation in the infrared and/or to radiation in the ultraviolet.
• the electrodes are of opposite polarity, i.e. they are intended to be electrically supplied by electrical voltages of opposite signs.
• the polarity electrodes may each include a comb having a branch from which fingers extend.
• the combs are interdigitated.
• Each of the fingers of a comb can have a width equal to the fundamental wavelength of the surface ultrasonic wave or the Lamb wave, divided by 4 and the spacing between two consecutive fingers of a comb can be equal to the fundamental wavelength of the ultrasonic surface wave or the Lamb wave, divided by 4.
• the spacing between the fingers determines the resonant frequency of the transducer which the person skilled in the art can easily determine .
• the alternating electrical voltage of the electrodes of opposite polarity induces a mechanical response of the piezoelectric material, which results in the generation of an ultrasonic surface wave or a Lamb wave which propagates in the optical surface.
• the electrodes can be metallic. They can be in chromium, or aluminum or in the combination of a bonding layer such as titanium and a conductive layer such as gold.
• the electrodes can be made of a conductive transparent oxide, for example chosen from indium tin oxide, zinc oxide doped with aluminum and mixtures thereof.
• the transducer can be transparent and be formed from such electrodes and from a transparent piezoelectric layer of lithium niobate or zinc oxide. The transducer can thus be advantageously placed in the optical field of the device, for example to optimize the cleaning of the optical surface, without significantly disturbing the operation of the device by shading effect.
• the electrodes can be deposited on the piezoelectric layer by an evaporation or sputtering process and shaped by photolithography.
• They can be printed, for example by inkjet printing.
• they can be printed on a foil, for example made of a flexible thermoplastic material, and be applied by transferring the foil onto the piezoelectric layer.
• the transducer can be configured to emit a surface ultrasonic wave or a Lamb wave whose fundamental frequency can be between 0.1 MHz and 1000 MHz, preferably between 10 MHz and 100 MHz, for example equal to 40 MHz, and/or the amplitude can be between 1 nanometer and 500 nanometers.
• the amplitude of the wave corresponds to the normal displacement of the face of the optical surface on which the ultrasonic surface wave propagates. It can be measured by laser interferometry.
• the ultrasonic surface wave can be a Rayleigh wave, when the optical surface has a thickness greater than the wavelength of the ultrasonic surface wave.
• a Rayleigh wave is favored because a maximum proportion of the wave's energy is concentrated on the face of the optical surface on which it propagates, and can be transmitted to a body, for example a raindrop, resting on the optical surface.
• the device comprises at least two transducers, for example more than five, or even more than ten transducers.
• the transducers can be configured to emit surface acoustic waves propagating in parallel or secant directions.
• the device comprises at least three transducers which are configured so that the directions of propagation of the waves which they are able to generate intersect in a common place.
• the transducers can be distributed regularly over the contour of the face of the optical surface on which they are arranged.
• the transducers share the same piezoelectric layer.
• the electrodes of the different transducers can be in contact with the same piezoelectric layer.
• Such a device is thus easy to manufacture, by successive implementation of a step of depositing the piezoelectric layer followed by a step of depositing the electrodes to form the transducers.
• the optical surface can be self-supporting, in the sense that it can deform, in particular elastically, without breaking under its own weight.
• the face of the optical surface on which the ultrasonic surface wave or the Lamb wave propagates can be planar. It can also be curved, provided that the radius of curvature of the face is greater than the wavelength of the ultrasonic surface wave. Said face may be rough. The roughnesses will preferably be lower than the fundamental wavelength of the ultrasonic surface wave, in order to prevent them from significantly affecting their propagation.
• the optical surface may be in the form of a flat plate, or having at least one curvature in one direction. In particular, it may be a lens.
• the thickness of the plate can be between 100 ⁇ m and 5 mm.
• the length of the plate may be greater than 1 mm, or even greater than 1 cm, or even greater than 1 m.
• thickness of the optical surface we consider the smallest dimension of the optical surface measured in a direction perpendicular to the surface on which the surface ultrasonic wave or the Lamb wave propagates.
• the optical surface can be laid flat relative to the horizontal. As a variant, it can be inclined with respect to the horizontal by an angle ⁇ greater than 10°, or even greater than 20°, or even greater than 45°, or even greater than 70°. It can be arranged vertically.
• the optical surface is preferably optically transparent, in particular to light in the visible or to radiation in the ultraviolet or in the infrared.
• the optical surface may comprise a monolayer or multilayer coating which covers one face of the acoustically conductive portion.
• the coating may in particular comprise a hydrophobic layer, an antireflection layer or a stack of these layers.
• the hydrophobic layer consists of self-assembled OTS monolayers or may result from the deposition of a fluorine-based plasma.
• the coating may include one or more anti-reflective layers depending on the intended application (Visible, IR, . . .).
• the transducer may be in contact with the acoustically conductive portion and the hydrophobic layer may entirely cover the transducer, in order to protect it from contact with water.
• the coating is placed between the transducer and the acoustically conductive portion.
• the optical surface includes an acoustically conductive portion, the transducer being acoustically coupled to, and preferably in contact with, the acoustically conductive portion.
• the acoustically conductive portion is preferably transparent.
• the acoustically conductive portion preferably has an attenuation length greater than the length of the optical surface, or even greater than 10 times the length of the optical surface, or even greater than 100 times the length of the optical surface.
• the acoustically conductive portion can be made of any material capable of propagating an ultrasonic surface wave or a Lamb wave.
• it is made of a material having a modulus of elasticity greater than 1 MPa, for example greater than 10 MPa, or even greater than 100 MPa, or even greater than 1000 MPa, or even greater than 10,000 MPa.
• a material having such a modulus of elasticity has a rigidity particularly suited to the propagation of an ultrasonic surface wave or a Lamb wave.
• the acoustically conductive portion is made of glass or of poly(methyl methacrylate), also known under the commercial reference Plexiglas®.
• the optical surface may consist of the acoustically conductive portion.
• the optical surface may include an acoustically insulating portion, that is to say absorbing the surface ultrasonic wave or the Lamb wave over a distance less than the length of the optical surface, or even less than 0 ,1 times the length of the optical surface.
• the acoustically insulating portion is preferably superposed, in particular entirely, on the acoustically conducting portion.
• the part acoustically insulating can fully cover the acoustically conductive portion.
• the acoustically insulating portion is made of polycarbonate. Other rubber or plastic materials can be considered.
• the acoustically insulating portion is preferably transparent.
• the acoustically insulating portion and the acoustically conducting portion can be stacked on top of each other, and preferably in contact with each other.
• the acoustically conductive portion may have a thickness at least five times less than the thickness of the acoustically insulating portion.
• the acoustically insulating portion can confer mechanical resistance to the optical surface while the acoustically conducting portion ensures the cleaning function by transporting the ultrasonic wave.
• the acoustically conductive portion can be removably mounted on the acoustically insulating portion.
• the acoustically conductive portion can be bonded to the acoustically insulating portion by means of a reversible adhesive.
• the device is configured to capture and/or emit radiation. To this end, it comprises a sensor and/or a radiation emitter.
• the device can be chosen from an optical remote sensing device, for example a lidar, a photographic device, a camera, a radar, an infrared sensor and an ultrasonic rangefinder.
• an optical remote sensing device for example a lidar, a photographic device, a camera, a radar, an infrared sensor and an ultrasonic rangefinder.
• the optical surface can be superimposed on the sensor and/or on the transmitter, in particular in order to protect the sensor.
• the optical surface is at a distance from the sensor and/or from the transmitter.
• It can be a lens intended to deflect the radiation in the direction of the sensor or coming from the transmitter.
• it can be an optical protection device, for example to protect the sensor and/or the transmitter.
• An “optical shield” is such that it does not deviate the optical path of radiation passing through it.
• the device comprises the optical surface which is a lens or the optical surface is a protective member of the device.
• the device can be a motor vehicle and the device is configured to acquire a quantity chosen from among the distance between the vehicle and an object, the speed of the vehicle, the positioning of the vehicle relative to a traffic lane, as well as any additional information such as the nature of the vehicle (truck, bicycle%) or the nature of objects (civilians, animals).
• the optical surface can be a substrate of a laboratory on chip, in particular intended for microfluidic applications.
• the optical surface can be a wall exposed to the condensation of a liquid that can solidify, for example a building's glazing.
• the device in particular the apparatus, may comprise a box in which the sensor and/or the transmitter are housed and the optical surface can be removably mounted on the box.
• the optical surface can be fixed on the box so as to seal the box hermetically, in order to protect the sensor and/or the transmitter.
• the optical surface can be fixed on a mount, which can be screwed onto the case. Thus, the optical surface can easily be replaced if it becomes damaged.
• the cleaning unit may include an electrical generator to electrically power the transducer, such that the transducer converts the electrical power signal into a surface ultrasonic wave or a Lamb wave.
• the invention also relates to the use of a device according to the invention, to evacuate a body in contact with the optical surface out of the optical region of interest.
• Use may include powering the cleaning unit to melt the body when the body is in a solid state, and/or maintain the body in a liquid state when the optical surface temperature is below the solidification temperature of the body.
• the body in the liquid state can be in the form of at least one drop or at least one film.
• the energy of the surface ultrasonic wave may be sufficient to induce the liquid state body to move across the face of the optical surface.
• the body can be aqueous, especially is rainwater or dewwater.
• the optical surface temperature may be below 0°C.
• the body is for example a frost or snow.
• the invention finally relates to a vehicle, preferably automated, or a member of such a vehicle comprising a device according to the invention.
• automated vehicle is meant a vehicle whose driving on the open road can be ensured without the intervention of a human driver.
• the vehicle is preferably a motor vehicle, in particular a car or a truck.
• a component of such a vehicle can be chosen from a lighting headlight module, a system containing a set of different sensors also called a "pod", at least one side window, a front window or a rear window and a control unit. driving assistance.
• Figure 1 schematically shows, in cross section, an example of a device according to the invention
• figure 2 schematically represents another example of a device
• FIG. 3 figure 3 schematically represents in front view, part of an example of a device according to the invention
• FIG. 4 figure 4 schematically represents in front view, part of another example of device according to the invention.
• FIG. 5 represents schematically and in cross section, part of an example of a device according to the invention
• FIG. 6 represents schematically and in cross section, part of another example of a device according to the invention.
• FIG. 7 represents schematically, and in cross-section, an example of a device according to the invention.
• Figure 1 a first example of device 5 according to the invention.
• the device comprises an optical surface 10, an optical surface cleaning unit 15 and an apparatus 20.
• the apparatus 20 includes a sensor 25 for capturing radiation R and a lens 30 for directing the radiation R towards the sensor. Alternatively or additionally, it may include a transmitter for emitting radiation.
• the apparatus includes a lidar that is configured to emit laser radiation and pick up back the object-reflected portion of that laser radiation.
• the lens 30 is optional. In an exemplary embodiment not shown, the apparatus is exempt from it.
• the device defines an optical field Co which corresponds to the portion of space from which it is able to acquire radiation. Outside this optical field, even if the radiation can reach the sensor, the latter is not able to acquire it.
• the optical surface 10 completely covers the sensor 25 and is thus a protective device 35 of the device.
• the device is mounted on a motor vehicle which can move in an X direction, the optical surface forms a barrier against bodies 40, such as dust, mud particles and raindrops which come into contact with the face 45 of the optical surface opposite the sensor.
• the optical surface is transparent to the radiation received by the sensor.
• the optical surface is for example made of glass. However, it can be made of a material that is opaque to radiation in the visible but transparent to the wavelengths of the radiation that the sensor is able to acquire.
• the optical surface is in the form of a disc whose thickness e p is for example between 0.5 mm and 5 mm.
• the optical surface can be curved, and for example have the shape of a lens.
• the device may comprise, as illustrated, a box 50 which defines a chamber 55 housing the sensor.
• the chamber 55 can in particular be delimited by a solid wall 60 of the case and by the optical surface 10, so as to be airtight and watertight. The sensor is thus protected from the weather.
• the optical surface can block the box.
• the optical surface is mounted on a ring 65, which is screwed onto the housing 50.
• optical surface is thus removable, which allows its simple replacement when for example it has been damaged by a projectile.
• the optical surface cleaning unit 15 comprises two transducers 70 which are arranged in contact with the optical surface and which are acoustically coupled with the optical surface.
• the cleaning unit further includes a current generator 75 to power the transducers electrically.
• the number of transducers is not limiting.
• the device may comprise a single transducer.
• the transducers also each comprise a piezoelectric layer 80 and electrodes 85 of opposite polarity arranged on the piezoelectric layer. Such layered transducers thus allow the manufacture of particularly compact devices. They can also be easily placed on curved optical surfaces.
• the transducers can each generate a surface ultrasonic wave Ws or a Lamb wave Wi which propagates in the optical surface.
• the transducers are arranged on the face 90 of the optical surface opposite the face to be cleaned 45. They are preferably configured to generate a Lamb wave which reaches the face to be cleaned 45.
• the transducers delimit a region of optical interest 100 which is not superimposed with the transducers.
• part of the optical region of interest is contained within the optical field of the device.
• the transducers are arranged outside the optical field of the device, so that they do not substantially interfere with the radiation passing through the optical region of interest and which is picked up by the sensor.
• the transducers are preferably arranged on the periphery of the optical surface.
• the wave transducers can in particular each extend from an edge of the optical surface over a distance of less than 10%, or even less than 5% of the length of the optical surface.
• the transducers extend across face 90 directly from edge 105.
• the device of FIG. 2 differs from that illustrated in FIG. 1 in that the transducers 70 are arranged on the face to be cleaned 45 of the optical surface 10 which is opposite the face 90 opposite the sensor 25.
• the transducers are preferably configured to generate an ultrasonic surface wave Ws propagating along the face to be cleaned 45 in order to move a body in contact with said face.
• FIG. 3 illustrates part of a device 5 according to the invention according to a view perpendicular to one of the faces 45, 90 of the optical surface.
• Two transducers are arranged in contact with one of the faces of the optical surface. They each comprise a piezoelectric layer 80 which is in contact with the optical surface and which extends in band B between two opposite edges 120 and parallel to a third edge 125 which connects these two opposite edges. Electrodes 85 of opposite polarity and comprising interdigitated combs are arranged on the piezoelectric layer, and are arranged in such a way as to generate an ultrasonic wave of Lamb WL OR of surface Ws which propagates in the region of optical interest, in order to clean the bodies 40 deposited thereon.
• the portion of the device represented in FIG. 4 differs from that illustrated in FIG. 3 in that the transducers 70 share the same piezoelectric layer 80 which delimits a frame 130 surrounding the optical region of interest 100.
• the frame is for example rectangular. It has an outer contour 135 which coincides with the contour of the face of the optical surface on which the piezoelectric layer is deposited.
• the device may comprise a greater number of transducers, arranged for example in a regular manner around the frame.
• the electrodes 85 can be printed on the piezoelectric layer.
• An arrangement of the transducers as described in Figures 3 and 4 can of course be implemented in the examples illustrated in Figures 1, 2 and 7.
• FIG. 5 illustrates a sectional view of a part of the device of FIG. 3.
• the optical surface 10 comprises an acoustically conductive portion 150, for example made of glass, and a coating 155 completely covering a face 160 of the acoustically conductive portion , and constituted by the stacking of an antireflection layer 165 and a hydrophobic layer 170, in order for example to prevent raindrops from spreading on the optical surface and to facilitate their evacuation.
• the transducer 70 is placed in contact with the coating opposite the acoustically conductive portion.
• the coating preferably has a sufficiently small thickness with regard to the wavelength of the surface wave generated by the transducer.
• the acoustically conductive portion and the transducer are acoustically coupled.
• FIG. 7 further illustrates an embodiment of a device 5 according to the invention. It differs from the example of FIG. 2 in that the optical surface is a lens 178 comprising an acoustically conducting portion 150 and an acoustically insulating portion 180 stacked on top of each other.
• the lens 178 In addition to its ability to modify the path of radiation passing through it, the lens 178 also protects the sensor 25.
• the acoustically insulating portion is for example thicker than the acoustically insulating portion and can mechanically support the acoustically conducting portion.
• the transducer is acoustically coupled to the acoustically conductive portion.
• the acoustically conductive portion can be mounted in a removable manner, for example by means of a layer of reversible adhesive placed between the opposite faces of the acoustically insulating portion and of the acoustically conductive portion.
• a layer of reversible adhesive placed between the opposite faces of the acoustically insulating portion and of the acoustically conductive portion.
• the acoustically conductive portion 150 is arranged opposite the sensor 25 with respect to the acoustically insulating portion 180.
• the cleaning unit can clean the face 45 of the acoustically conductive portion on which bodies 40, for example drops rain can accumulate.

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• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• General Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Mechanical Engineering (AREA)
• Computer Networks & Wireless Communication (AREA)
• Radar, Positioning & Navigation (AREA)
• Remote Sensing (AREA)
• Transducers For Ultrasonic Waves (AREA)
• Cleaning By Liquid Or Steam (AREA)
• Cleaning In General (AREA)
• Apparatuses For Generation Of Mechanical Vibrations (AREA)

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• 2020
  • 2020-12-14 FR FR2013212A patent/FR3117384A1/fr not_active Withdrawn
• 2021
  • 2021-12-13 EP EP21839084.7A patent/EP4260122A1/fr active Pending
  • 2021-12-13 WO PCT/EP2021/085483 patent/WO2022128914A1/fr active Application Filing
  • 2021-12-13 US US18/267,280 patent/US20240045200A1/en active Pending
  • 2021-12-13 JP JP2023535958A patent/JP2023554020A/ja active Pending
  • 2021-12-13 CN CN202180090533.1A patent/CN116710831A/zh active Pending

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