FI20195347A1

FI20195347A1 - Apparatus for cleaning a window product from precipitation and/or debris by using ultrasonic waves

Info

Publication number: FI20195347A1
Application number: FI20195347A
Authority: FI
Inventors: Jan Kinnunen
Original assignee: Kongsberg Maritime Finland Oy
Priority date: 2019-04-29
Filing date: 2019-04-29
Publication date: 2020-10-30
Also published as: FI129239B

Abstract

The present disclosure relates generally to ultrasonic cleaning, and more specifically, to an apparatus for cleaning a window product from precipitation and/or debris by using ultrasonic waves. For this purpose, the apparatus comprises an ultrasonic generator, an array of ultrasonic transducers, and an attenuating material. The ultrasonic generator is configured to produce ultrasonic signals that are fed to the array of ultrasonic transducers in order to cause the ultrasonic transducers to generate ultrasonic waves in the direction of the window product to be cleaned. The attenuating material is either arranged continuously around the periphery of the window product or enveloping each of the array of ultrasonic transducers. The attenuating material is configured to attenuate the ultrasonic waves such that the ultrasonic waves reaching the window product cause the window product to vibrate without damage thereto, while cleaning the window product from the precipitation and/or debris. This embodiment of the apparatus may provide the surface cleaning of the window product more efficiently and safely for the window product.

Description

APPARATUS FOR CLEANING A WINDOW PRODUCT FROM PRECIPITATION

AND/OR DEBRIS BY USING ULTRASONIC WAVES

TECHNICAL FIELD

The present disclosure relates generally to ultrasonic cleaning, and more specifically, to an apparatus for cleaning a window product from precipitation and/or debris by using ultrasonic waves.

BACKGROUND

Window products, such as vehicle windows, camera windows, viewing windows, etc., tend to be contaminated by different debris or precipitation, for which reason their transparence becomes worse. For example, this may make it problematic or even impossible for a driver to see a road through a dirty windshield, or lead to the occurrence of different artifacts in images or videos captured by a thermal or visual camera having a dirty camera window.

To avoid the above-mentioned or other problems caused by the surface contamination of the window products, one may remove the debris or precipitation from the window products manually, for example, by using special brushes. However, such manual o removal is cumbersome and often ineffective. There are also > 25 automated cleaning means, such as wipers used to remove rain, x snow, ice and other kinds of the debris or precipitation from > a vehicle windshield, but they tend to be worn out over time

T due to the constant mechanical contact with the windshield and

N therefore need to be replaced regularly. Other examples of the 3 30 automated cleaning means especially used in vehicles include 2 a defroster and a defogger, but both of them are used to remove

N a certain kind of the precipitation, i.e. ice and weeping, respectively.

As for the camera windows or viewing windows, their surfaces may be cleaned from the debris or precipitation by means of mechanical vibrations transferred to the camera windows or viewing windows from closely-spaced vibration transducers, such as ultrasonic transducers. In the meantime, these mechanical vibrations may cause damage to the camera windows or viewing windows and thereby should be used carefully in the cleaning process.

SUMMARY

This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

It is an object of the present disclosure to provide an apparatus for cleaning a window product from any precipitation and/or debris by using ultrasonic waves, without causing any damage to the window product. o 2 It is a further object of the present disclosure to provide an 3 25 apparatus for cleaning different kinds of window products, 2 particularly camera windows and vehicle windows, from any

E precipitation and/or debris by using ultrasonic waves.

N

3

D The objects above and other advantages may be achieved by an

N 30 apparatus for cleaning a window product from precipitation and/or debris by using ultrasonic waves, which is characterized in the independent claim of the appended claims. Different embodiments of the apparatus are defined in the dependent claims of the appended claims, detailed description and drawings.

More specifically, the apparatus comprises an ultrasonic generator, an array of ultrasonic transducers, and an attenuating material. The ultrasonic generator is configured to produce ultrasonic signals that are fed to the array of ultrasonic transducers in order to cause the ultrasonic transducers to generate ultrasonic waves in the direction of the window product to be cleaned. The attenuating material is either arranged continuously around the periphery of the window product or enveloping each of the array of ultrasonic transducers. The attenuating material is configured to attenuate the ultrasonic waves such that the ultrasonic waves reaching the window product cause the window product to vibrate at a vibration amplitude less than a maximum allowable vibration amplitude of the window product, while cleaning the window product from the precipitation and/or debris. This embodiment of the apparatus may provide the surface cleaning of the window product more efficiently and safely for the window product. 2

I 25 In one embodiment, the ultrasonic generator is configured to x produce the ultrasonic signals for each of the array of > ultrasonic transducers alternately or simultaneously. This may = make the apparatus more flexible in use. a 3

S 30 In one embodiment, the ultrasonic generator is configured to

S produce the ultrasonic signals in pre-defined regular time intervals. By so doing, one may make the apparatus more automated, i.e. reduce manual work, and reduce the risk of ice formation on the window product (in case of low ambient temperatures).

In one embodiment, the attenuating material comprises an elastic material. This may protect the window product from any damage due to its vibration more efficiently.

In another embodiment, the attenuating material comprises a fluid encapsulated in an elastic envelope. This may protect the window product from any damage due to its vibration more efficiently.

In one embodiment, the ultrasonic generator is configured to produce the ultrasonic signals having a frequency from the range of 100 kHz to 400 kHz and a power from the range of 30

W to 40 W. In this case, the attenuating material is configured such that the ultrasonic waves are attenuated to a frequency from the range of 25 kHz to 40 kHz and a power from the range of 10 to 20 W before reaching the window product. By using such high frequencies, one may provide the atomization of water vapors and possible small debris particles, thereby making the surface of the window product cleaner. > & 3 25 In one embodiment, the array of ultrasonic transducers 2 comprises piezoelectric and/or capacitive transducers. This

E may make the apparatus more flexible in use.

N

3

D In one embodiment, the window product comprises a camera window

N 30 provided on a hollow camera tube for a thermal or visual camera. In this embodiment, the array of ultrasonic transducers are arranged on the inside of the camera tube near the camera window. This may make it possible to use the apparatus to clean the surface of the camera window from the debris or precipitation. 5

In one embodiment, the array of ultrasonic transducers are all arranged on the inside of the camera tube at the same distance from each other. This may provide an omnidirectional and uniform effect of ultrasonic waves on the window product.

In one embodiment, the apparatus further comprises an auxiliary vibration means attached to the camera tube opposite to the camera window and configured to produce low-frequency sonic waves around the camera tube and the camera window. The low- frequency sonic waves in concert with the ultrasonic waves may provide better surface cleaning of the window product as well as the camera tube itself.

In one embodiment, the auxiliary vibration means comprises: a rotatable crankshaft-like device, a tube attached opposite to the camera window, and a piston-like element arranged inside the tube. The crankshaft-like device is configured, when rotated, to move the piston-like element back and forth inside = the tube. This may provide a more efficient production of low- 5 25 frequency vibrations around the camera tube and the camera <? window.

Q

= a

N In one embodiment, the auxiliary vibration means comprises an 3 electrostatic loudspeaker. This may provide a more efficient 2 30 production of low-frequency vibrations around the camera tube

N and the camera window.

In one embodiment, the auxiliary vibration means is configured to produce the low-frequency sonic waves having frequencies from the range 17 to 30 Hz. This may provide more efficient surface cleaning of the window product, as well as the camera tube and different mechanical parts attached to the camera tube, like, for example, a sun visor.

In one embodiment, the array of ultrasonic transducers comprises a pair of opposite ultrasonic transducers, with one of the pair of opposite ultrasonic transducers being further configured to receive the ultrasonic wave generated by another of the pair of opposite ultrasonic transducers. In this embodiment, the apparatus further comprises a measuring device coupled to the pair of opposite ultrasonic transducers and configured to measure a speed wave of the ultrasonic wave. By so doing, one may understand when the interior of the camera tube is full of debris particles, and remove the debris particles from the camera tube manually.

In another embodiment, the window product comprises a vehicle window, and the array of ultrasonic transducers is arranged around the periphery of the vehicle window. This may make the apparatus more flexible in use. > & + 25 In yet another embodiment, the window product comprises a = vehicle window or helmet windshield provided with wipers. In - this embodiment, the array of ultrasonic transducers is

E enveloped by the attenuating material and evenly arranged on 3 the wipers. This may make the apparatus more flexible in use.

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S 30

Other features and advantages of the present disclosure will be apparent upon reading the following detailed description and reviewing the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The essence of the present disclosure is explained below with reference to the accompanying drawings in which:

FIG. 1 shows a simplified block-scheme of an apparatus for cleaning a window product from debris and/or precipitation by using ultrasonic waves in accordance with one embodiment of the present disclosure;

FIGS. 2 and 3 show one practical situation in which the apparatus shown in FIG. 1 is used to remove the debris and/or precipitation from camera windows;

FIG. 4 shows one other practical situation in which the apparatus shown in FIG. 1 is used to remove the debris and/or precipitation from a car windshield; and

FIG. 5 shows yet another practical situation in which the apparatus shown in FIG. 1 is used to remove the debris and/or precipitation from the car windshield.

DETAILED DESCRIPTION o

S Various embodiments of the present disclosure are further x described in more detail with reference to the accompanying

SE 25 drawings. However, the present disclosure can be embodied in

Ek many other forms and should not be construed as limited to any a

N certain structure or function disclosed in the following + 2 description. In contrast, these embodiments are provided to

O

S make the description of the present disclosure detailed and

N complete.

According to the present disclosure, it will be apparent to those skilled in the art that the scope of the present disclosure covers any embodiment, which is disclosed herein, irrespective of whether this embodiment is implemented independently or in concert with any other embodiment of the present disclosure. For example, the apparatus disclosed herein can be implemented by using any numbers of the embodiments provided herein. Furthermore, it should be understood that any embodiment of the present disclosure can be implemented using one or more of the elements presented in the appended claims.

In embodiments of the present disclosure, a window product may refer to a window of a ground, space, air, marine or submarine vehicle, a camera window, a viewing window, an inspection window or any other type of translucent windows. It should be noted that the window product is not necessarily made of glass only, i.e. the glass itself may be the main material of the window product but not the only possible. For example, a vehicle windshield may have a laminated structure, with some layers being made of optical polymers, or a composite structure comprising different composite materials. o According to the embodiments of the present disclosure, > 25 precipitation may refer to any product of the condensation of x atmospheric water vapor under gravity, such as rain, sleet, > fog, snow, ice, drizzle, mist, etc. The precipitation may, for

T example, worsen the driver’s view of a road when falling onto

N a vehicle windshield, or may cause the occurrence of artifacts 3 30 on images or videos captured by a thermal or visual camera 2 when falling on a camera window.

N

As used in the embodiments of the present disclosure, debris may refer to scattered, broken, or fragmented pieces of rubbish or remains, such as dirt, dust particles, or the like. Similar to the precipitation, the debris present on the surface of the window product may also cause the above-described problems with the driver’s vision or the occurrence of the artifacts on the camera images or videos.

In embodiments of the present disclosure, ultrasonic waves may refer to such sonic waves having frequencies higher than the upper audible limit of human hearing, i.e. from 20 kHz to several GHz. The ultrasonic waves are intended to be generated as a result of driving an ultrasonic transducer with the aid of an ultrasonic signal from an ultrasonic generator. The propagation direction of the ultrasonic waves as well as their waveform and power may depend on the type and arrangement of the transducer and a propagation medium. It is the power of the ultrasonic waves which may allow removing or preventing the occurrence of the debris and/or precipitation on the window product, but at the same time may cause damage to the window product. Therefore, the proper selection of the power of the ultrasonic waves is crucial to obtain acceptable results of ultrasonic cleaning and remain the window product undamaged.

As will be discussed later, it is achieved by arranging an

D 25 attenuating material between the ultrasonic transducers and

N the window product to be cleaned. The ultrasonic transducers

S used in the embodiments of the present disclosure may comprise

Q piezoelectric and/or capacitive transducers. i 5 MON 2 30 FIG. 1 shows a simplified block-scheme of an apparatus 100 for 2 removing the precipitation and/or debris from the window

N products by using the ultrasonic waves in accordance with one embodiment of the present disclosure. The apparatus 100 comprises the following constructive elements: an ultrasonic generator 102, an array of ultrasonic transducers 104-1-104- n, and an attenuating material 106. The ultrasonic generator 102 is configured to produce, continuously or in irregular or pre-defined regular time intervals, ultrasonic signals that are fed alternately or simultaneously to the ultrasonic transducers 104-1-104-n in order to cause the ultrasonic transducers 104-1-104-n to generate ultrasonic waves 110-1- 110-n, respectively, which propagate in the direction of a window product 108 to be cleaned. The ultrasonic waves 110-1- 110-n are schematically shown in FIG. 1 as sets of dashed lines. The attenuating material 106 is arranged between the ultrasonic transducers 104-1-104-n and the window product 108 and is configured to attenuate the ultrasonic waves 110-1-110- n such that the ultrasonic waves 110-1-110-n reaching the window product cause the window product 108 to vibrate without damage thereto, while cleaning the window product 108 from debris particles 112-1-112-4. This attenuation of the ultrasonic waves 110-1-110-n is schematically shown in FIG. 1 as the dashed lines with reduced lengths. It should also be noted that there could be a different number of the debris particles and/or a layer of any precipitation onto the surface of the window product 108, instead of the four debris particles 112-1-112-4 shown. With such configuration, the apparatus 100 may provide the surface cleaning of the window product 108 2 more efficiently and safely for the window product 108 itself. 3

Q In other embodiments of the present disclosure, the array of

E ultrasonic transducers may comprise any number of the 5 30 ultrasonic transducers, but that number should be equal to at

O least two. The arrangement of the ultrasonic transducers may > be selected such that they are in the vicinity of the window product 108. Although FIG. 1 shows the ultrasonic transducers 104-1-104-n arranged as a one-dimensional array, this should not be construed as any limitation of the present disclosure.

Any other arrangements are also possible, such, for example, as a matrix arrangement of the ultrasonic transducers 104-1- 104-n, depending on particular application. Different embodiments of the arrangements of the ultrasonic transducers will be discussed later with reference to FIGS. 2-5.

In one other embodiment of the present disclosure, the attenuating material 106 may be arranged continuously around the periphery of the window product 108, thereby significantly reducing the risk of breaking the window product 108 due to its vibration caused by the ultrasonic waves 110-1-110-n. In yet another embodiment, the same or similar effect may be achieved by encapsulating each of the ultrasonic transducers 104-1-104-n in the attenuating material 106.

In one embodiment of the present disclosure, the attenuating material 106 may be represented by any type of elastic materials. Some examples of the elastic materials include elastomers, such as natural rubber, synthetic rubber, silicone rubber, or bulk semiconductors, such as bulk silicon. The attenuating material 106 should be selected such that the ultrasonic waves passed through it cause the window product o 108 to vibrate at a vibration amplitude less than a maximum > 25 allowable vibration amplitude of the window product 108. Here x the maximum allowable vibration amplitude should be construed > as that above which the window product 108 will be broken with = high probability. Values of the maximum allowable vibration

N amplitude depends on the type of material(s) which the window 3 30 product 108 consists of. In general, such values may be found 2 in special technical reference guides or measured

N experimentally before using the apparatus 100. The ultrasonic waves thus attenuated are likely to be "soft” to the window product 108, while being effective in the surface cleaning thereof. In another embodiment, the attenuating material 106 may comprise a liquid, such, for example, as oil and water, or a gas, such, for example, as helium and air, which is encapsulated in an elastic or plastic envelope. Such a liquid- based or gas-based attenuating material may allow one to obtain the same or similar attenuation effect as discussed above.

One numerical example will be now given for illustrative but not limitative purposes. Assuming that the ultrasonic generator 102 is configured to produce the ultrasonic signals having a frequency from the range of 100 kHz to 400 kHz and a power from the range of 30 W to 40 W. These ultrasonic signals, in turn, cause the ultrasonic transducers 104-1-104-n to generate the ultrasonic waves or vibrations 110-1-110-n with the same or similar frequency and power (with neglect of propagation losses inside cables or wirings connecting the ultrasonic generator 10? and each of the ultrasonic transducers 104-1-104-n). Being applied to the fragile window product 108, like the camera window, such ultrasonic waves 110-1-110-n may result in cracking or even breaking the window product 108. In order to avoid these negative outcomes, the attenuating material 106 should be selected and arranged such that the ultrasonic waves 110-1-110-n are attenuated, say, to a

D 25 freguency from the range of 25 kHz to 40 kHz and a power from

N the range of 10 to 20 W before reaching the window product

S 108. The ultrasonic waves 110-1-110-n thus attenuated may allow

Q the window product 108 to be cleaned from the debris and/or z precipitation present thereon and to remain undamaged after 5 30 said ultrasonic exposure. It should also be noted that the

O higher frequencies of the ultrasonic signals require the higher > powers thereof in order for the window product 108 to be cleaned by the attenuated ultrasonic waves 110-1-110-n more efficiently.

With reference to FIGS. 2 and 3, a practical situation will be now described, in which the apparatus 100 is used to remove the debris and/or precipitation from the surfaces of camera windows in accordance with one other embodiment of the present disclosure. FIG. 2 is a longitudinal view of a camera tube 200 having two cameras 202 and 204 installed therein, while FIG. 3 is a cross-section of the camera tube 200 (which is taken when viewing in the direction A). The cameras 202 and 204 may be of the same type or different types. For example, the camera 202 may be a thermal camera, while the camera 204 may be a visual camera, or vice versa. In turn, the visual camera may be implemented as a visual surveillance camera too. The cameras 202 and 204 are provided with camera windows 206 and 208, respectively, which are used as transparent protection covers.

The camera windows 206 and 208 need to be cleaned regularly because they may be contaminated by the debris and/or precipitation. This 1s especially important to do in cases when the camera tube 200 is mounted on shipboard because ice formation occurs very quickly on the sea. To prevent the problem of the surface contamination, for example, due to the ice formation, one may arrange the ultrasonic transducers near the window cameras 206 and 208, preferably on the interior surface of the camera tube 200. If the camera tube 200 has a o 25 circular cross-section, as shown in FIG. 3, the ultrasonic > transducers 104-1-104-n may be located radially (as shown by x a clockwise arrow in FIG. 3) at some distance from the camera > windows 206 and 208. In this embodiment, the attenuating = material 106 is implemented as two (black-filled) sealing

N 30 rings, with one surrounding the camera window 206 and another 3 surrounding the camera window 208. The sealing rings prevent 2 the direct contact between the ultrasonic waves generated by

N the ultrasonic transducers 104-1-104-n and the camera windows 206 and 208, thereby minimizing the potential risk of cracking or breaking the camera windows 206 and 208 but providing the proper removal of the debris and/or precipitation from the surfaces of the camera windows 206 and 208.

In one embodiment, the ultrasonic transducers 104-1-104-n may be arranged on the inside of the camera tube 200 radially at the same angular distance from each other. For example, the angular distance may be equal to 45°, which means that there are eight ultrasonic transducers to be used for the ultrasonic cleaning of the camera windows 206 and 208. However, the present disclosure 1s not limited to this number of the ultrasonic transducers, and the array of ultrasonic transducers may comprise less or more than eight ultrasonic transducers depending on particular application.

In one more embodiment, the ultrasonic generator 102, which is not shown in FIGS. 2 and 3, may drive each of the ultrasonic transducers 104-1-104-n alternately or simultaneously. The ultrasonic generator 102 may be arranged either inside the camera tube 200 if its sizes allow doing this, or remotely from the camera tube 200. Irrespective of which arrangement of the ultrasonic generator 102 is used, the ultrasonic transducers 104-1-104-n may be coupled to the generator 102 by o means of cables or wirings suitable for ultrasonic frequencies > 25 (in order to minimize propagation losses). 3 o - One other embodiment is possible, in which the apparatus 100 a further comprises an auxiliary vibration means configured to 3 produce low-freguency sonic waves or vibrations around the 3 30 camera tube 200 and the camera windows 206 and 208. More specifically, the vibration means may be implemented as a piston-like element 210 configured to move back and forth at a low frequency inside a tube 212 attached opposite to the camera windows 206 and 208. By said moving, the piston-like element 210 causes air inside the camera tube 200 to move at the same low frequency, thus causing some form of low-frequency vibrations around the camera tube 200 and camera windows 206 and 208. In one embodiment, the piston-like element 210 may be set in motion by using a rotatable crankshaft-like device (not shown in FIGS. 2 and 3). One example of the crankshaft-like device is the one used in internal combustion engines of cars.

In another embodiment, the auxiliary vibration means may be implemented as an electroacoustic loudspeaker, in which the piston-like element 210 is represented by a diaphragm configured to vibrate by a varying electrostatic field. The low-freguency sonic waves or vibrations produced by the auxiliary vibration means have a higher energy compared to the ultrasonic waves, and may be used to remove the bigger debris and/or precipitation not only from the camera windows 206 and 208 but also from the whole surface of the camera tube 200 itself. The auxiliary vibration means may be configured such that it produces the low-frequency sonic waves having frequencies from the range 17 to 30 Hz. Thus, the configuration of the apparatus 100, which is shown in FIGS. 2 and 3, provides for the combined action of the ultrasonic waves from the ultrasonic transducers 104-1-104-n and the low-frequency sonic waves from the auxiliary vibration means, i.e. the piston-line 2 element 210. 3

Q In yet another embodiment, any two opposite ultrasonic z transducers of the array of the ultrasonic transducers 104-1- 5 30 104-n arranged on the inside of the camera tube 200 may

O additionally be used to detect the presence of the debris > particles inside the camera tube 200. For example, said two opposite ultrasonic transducers may be represented by the ultrasonic transducers 104-4 and 104-n shown in FIGS. 2 and 3.

The ultrasonic transducer 104-4 may be used as a receiver for the ultrasonic wave generated by the ultrasonic transducer 104-n, or vice versa. In this embodiment, the apparatus 100 further comprises a measuring device 214 coupled to the ultrasonic transducers 104-4 and 104-n and configured to measure a wave speed of the ultrasonic wave propagating from the ultrasonic transducer 104-n to the ultrasonic transducer 104-4 across the interior surface of the camera tube 200. The wave speed is influenced by the composition of the air inside the camera tube 200: If the air is full of any debris particles, this will lead to decreasing the wave speed. To make it possible to implement such detection, the ultrasonic generator 102 should feed the ultrasonic signal to the ultrasonic transducer 104-n only, i.e. the rest ultrasonic transducers should be in an idle mode and the ultrasonic transducer 104-4 should be in a “waiting” mode (i.e. be ready to receive the ultrasonic wave). By taking such measurements of the wave speed before the operation of the camera tube 200 and during its operation, for example, on the sea, one may detect a difference in the wave speeds if the air inside the camera tube 200 is contaminated by the debris particles. In this case, the camera tube 200 may be opened and cleaned from the debris particles manually.

D 25 FIG. 4 shows another practical situation in which the apparatus

N 100 is used to remove the debris and/or precipitation from the

S vehicle window, namely a windshield 400, in accordance with

Q one more exemplary embodiment of the present disclosure. In

E the situation shown, the array of ultrasonic transducers is

S= 30 limited to the four ultrasonic transducers 104-1-104-4 each

O enveloped by the sealing ring made of the attenuating material > 106 and arranged (for example, by means of suitable adhesive agents) on the inside of the windshield 400, for example, at a corresponding corner. Again, the number and arrangement of the ultrasonic transducers are selected such for illustrative purposes only, and may be changed if required. The same is true for the windshield 400, which may be replaced with any other vehicle window, including a sunroof, in some other embodiments. Moreover, the vehicle window may be a window of any type of vehicles, such as an aircraft, vessel, car, submarine, etc. By so doing, the ultrasonic transducers 104- 1-104-4 may replace traditional wipers and serve as ultrasonic wipers. At the same time, the ultrasonic generator 102 may be hidden inside the interior panel of a vehicle cabin.

FIG. 5 shows one additional practical situation in which the apparatus 100 is used to remove the debris and/or precipitation from the vehicle window, namely a windshield 500, in accordance with one other exemplary embodiment of the present disclosure.

Contrary to the situation illustrated in FIG. 4, the ultrasonic transducers are now arranged evenly on wipers 502 and 504.

More specifically, a wiper blade of each of the wipers 502 and 504 1s additionally provided with a strip of ultrasonic transducers encapsulated in the attenuating material 106.

Similarly, the strips of ultrasonic transducers may be attached to the wiper blades of the wipers 502 and 504 with the aid of suitable adhesive agents. As shown in FIG. 5, the left wiper 502 comprises the strip of the ultrasonic transducers 104-1-

D 25 104-4, and the right wiper 504 comprises the strip of the

N ultrasonic transducers 104-5-104-8. During operation, the

S wiper blades of the wipers 502 and 504 is swung back and forth

Q over the windshield 500 and at the same time provides the

E ultrasonic waves from the ultrasonic transducers 104-1-104-8 5 30 to the windshield 500, thereby causing the windshield 500 to

O vibrate. The combination of such mechanical cleaning and > ultrasonic cleaning provides better removal of the debris and/or precipitation from the windshield 500. In this case,

the ultrasonic generator 102 may be hidden under hood, for example.

Although the exemplary embodiments of the present disclosure are described herein, it should be noted that any various changes and modifications could be made in the embodiments of the present disclosure, without departing from the scope of legal protection which is defined by the appended claims. In the appended claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “Yan” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. o

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Claims

1. An apparatus for cleaning a window product from a precipitation and/or debris by using ultrasonic waves, comprising: an ultrasonic generator configured to produce ultrasonic signals; an array of ultrasonic transducers configured, in response to receiving the ultrasonic signals from the ultrasonic generator, to generate ultrasonic waves propagating towards the window product; and an attenuating material either arranged continuously around the periphery of the window product or enveloping each of the array of ultrasonic transducers, the attenuating material being configured to attenuate the ultrasonic waves such that the ultrasonic waves reaching the window product cause the window product to vibrate at a vibration amplitude less than a maximum allowable vibration amplitude of the window product, while cleaning the window product from the precipitation and/or debris.

2. The apparatus of claim 1, wherein the ultrasonic generator is configured to produce the ultrasonic signals for each of the array of ultrasonic transducers alternately or simultaneously. o 25 o

3. The apparatus of claim 1 or 2, wherein the ultrasonic x generator is configured to produce the ultrasonic signals ER in pre-defined regular time intervals. I a 30

4. The apparatus of any one of claims 1 to 3, wherein the 3 attenuating material comprises an elastic material. O

S 5. The apparatus of any one of claims 1 to 3, wherein the attenuating material comprises a liguid or gas encapsulated in an elastic envelope.

6. The apparatus of any one of claims 1 to 5, wherein the ultrasonic generator is configured to produce the ultrasonic signals having a freguency from the range of 100 kHz to 400 kHz and a power from the range of 30 W to 40 W, and wherein the attenuating material is configured such that the ultrasonic waves are attenuated to a freguency from the range of 25 kHz to 40 kHz and a power from the range of 10 to 20 W before reaching the window product.

7. The apparatus of any one of claims 1 to 6, wherein the array of ultrasonic transducers comprises piezoelectric and/or capacitive transducers.

8. The apparatus of any one of claims 1 to 7, wherein the window comprises a camera window provided on a hollow camera tube for a thermal or visual camera, and wherein the array of ultrasonic transducers are arranged on the inside of the camera tube near the camera window.

9. The apparatus of claim 8, wherein all of the array of the ultrasonic transducers are arranged on the inside of the camera tube at the same distance from each other.

10. The apparatus of claim 8 or 9, further comprising an = auxiliary vibration means attached to the camera tube 5 opposite to the camera window and configured to produce = low-freguency sonic waves around the camera tube and the - 30 camera window. a a N

11. The apparatus of claim 10, wherein the auxiliary O vibration means comprises: a rotatable crankshaft-like > device, a tube attached opposite to the camera window, and a piston-like element arranged inside the tube, and wherein the crankshaft-like device is configured, when rotated, to move the piston-like element back and forth inside the tube.

12. The apparatus of claim 10, wherein the auxiliary vibration means comprises an electrostatic loudspeaker.

13. The apparatus of any one of claims 10 to 12, wherein the auxiliary vibration means is configured to produce the low-frequency sonic waves having frequencies from the range 17 to 30 Hz.

14. The apparatus of any one of claims 8 to 13, wherein the array of ultrasonic transducers comprises a pair of opposite ultrasonic transducers, and one of the pair of opposite ultrasonic transducers is further configured to receive the ultrasonic wave generated by another of the pair of opposite ultrasonic transducers, and wherein the apparatus further comprises a measuring device coupled to the pair of opposite ultrasonic transducers and configured to measure a wave speed of the ultrasonic wave.

15. The apparatus of any one of claims 1 to 7, wherein the window product comprises a vehicle window, and wherein the array of ultrasonic transducers is arranged around the periphery of the vehicle window. D

16. The apparatus of any one of claims 1 to 7, wherein N the window product comprises a vehicle or helmet S windshield provided with wipers, and wherein the array of Q 30 ultrasonic transducers 1s enveloped by the attenuating = material and evenly arranged on the wipers. 3 O N