Clearing solid state elements by acoustic wave transmission

Abstract

The invention relates to a method for cleaning solid elements (8), such as sand or dust particles, which may be present on the surface of an object (5), using at least one transducer (11) acoustically coupled to the object and comprising the steps of:-generating an electrical signal; applying an electrical signal across the terminals of the transducer; -thereby producing an acoustic wave propagating through the object, the acoustic wave being a surface wave or a Lamb wave and such that, under the action of the acoustic wave, the solid-state element moves over the surface of the object to clear from the surface.

Description

[0001] This invention relates to the field of surface cleaning where solid elements (such as sand, dust particles, etc.) may be present. These surfaces are, for example, the outer surface of a photovoltaic panel protective plate. Background Technology

[0002] The efficiency of a particular photovoltaic panel is a key parameter, which, together with the panel's cost and durability, determines its competitiveness in the global photovoltaic panel market.

[0003] However, it is known that photovoltaic panels experience a gradual decrease in efficiency due to the accumulation of solid elements. These solid elements adhere to the outer surface of the photovoltaic panel's protective sheet (also known as "protective glass," or simply "glass") and block light. These solid elements can be, for example, sand, dust particles, soil, insects, bird droppings, etc.

[0004] This is true for all photovoltaic panels, but it is especially true when they are installed in hot and arid regions. In these areas, the amount of dust that may accumulate on the panels is enormous. Nighttime condensation causes the dust to adhere strongly, and the lack of precipitation prevents the panels from cleaning themselves naturally.

[0005] Therefore, photovoltaic panels installed in hot and arid regions will lose an average of 1% of their energy generation efficiency per day before cleaning (2% on the second day, 3% on the third day, and so on).

[0006] Bird droppings also pose an additional risk, as they can completely obscure the protective panel on a very small local surface, potentially damaging the photovoltaic cells underneath.

[0007] Currently, cleaning solar panels requires on-site personnel to manually clean them. When the solar panels are located in remote areas, scheduling and coordinating these personnel is particularly challenging. Furthermore, large-scale solar farms require a large number of operators. These operators consume significant amounts of water while cleaning the panels.

[0008] Therefore, manual cleaning not only leads to high operating costs, but also affects the warranty of the photovoltaic panels if the cleaning personnel cause damage to them.

[0009] Automatic or semi-automatic solutions have been disclosed in the prior art, which are designed to overcome the above difficulties.

[0010] These solutions include, in particular, a robot-based approach that moves across the outer surface of a photovoltaic panel's protective cover. The robot is equipped with brushes, which it uses to clean the outer surface.

[0011] This solution has several flaws.

[0012] First, robots contain batteries and consumable parts that require regular maintenance, and they also contain complex components, so their lifespan is limited, much shorter than the typical 25-year warranty for solar panels.

[0013] These robots are also relatively expensive, which is a critical issue because, as mentioned earlier, the operating cost of photovoltaic panels is a key factor in determining their attractiveness.

[0014] In addition, in the long run, brushes may damage the anti-reflective coating on the outer surface of the photovoltaic panel's protective plate.

[0015] Moreover, these robots require regular maintenance due to the presence of easily damaged mechanical parts.

[0016] In addition, robots cannot cover the entire photovoltaic field at the same time, so even if robots are used, sand and dust will still inevitably reduce the production capacity of photovoltaic panels.

[0017] The aforementioned problems also exist, at least partially, on the surfaces of other types of objects, such as optical devices (cameras, viewfinders, etc.).

[0018] Purpose of the invention

[0019] The purpose of this invention is to effectively clean the surface of objects that may contain solid elements such as sand or dust particles in an automatic, simple and economical manner, without the need for manual water supply or maintenance operations, while reducing surface damage. Summary of the Invention

[0020] To achieve the above objectives, the present invention proposes a method for cleaning solid elements, such as sand or dust particles, that may be present on the surface of an object. This cleaning method uses at least one transducer acoustically coupled to the object and includes the following steps:

[0021] - Generate electrical signals;

[0022] - Apply the electrical signal across the terminals of the transducer;

[0023] This generates sound waves that propagate through the object (body), which are surface waves or Lamb waves, and under the action of these sound waves, the solid element moves on the surface of the object to be removed from the surface.

[0024] Therefore, the cleaning method of the present invention utilizes surface acoustic waves or Lamb waves to move solid elements on a contaminated surface and remove them from the surface.

[0025] This cleaning method has significant advantages. It can be implemented automatically without any manual operation and requires no artificial water supply (a major advantage for cleaning photovoltaic panels located in arid regions).

[0026] This cleaning method does not use brushes, which significantly reduces long-term damage to object surfaces. It requires no maintenance. The components used to generate the sound waves (electronic equipment, transducers) are low-cost and simple in structure, therefore their use does not reduce the overall lifespan or reliability of the object containing the surface being cleaned.

[0027] The present invention also proposes the above-mentioned cleaning method, wherein the frequency of the sound wave is between 1 MHz and 100 MHz.

[0028] The present invention also proposes the above-mentioned cleaning method, wherein solid elements are directly moved and removed by force generated by sound waves and transmitted through the contact between the surface of the object and the solid elements.

[0029] The present invention also proposes the above-mentioned cleaning method, wherein sound waves propagate through an object along a propagation direction and in a first direction, and wherein, under the action of the sound waves, solid elements move on the surface of the object along the propagation direction but in a second direction opposite to the first direction.

[0030] The present invention also proposes the above-mentioned cleaning method, wherein when a liquid element is present on the surface of an object, sound waves induce nonlinear acoustic phenomena of acoustic flow and / or radiation pressure, thereby moving the liquid element.

[0031] The present invention also proposes the above-mentioned cleaning method, which uses at least one first transducer and at least one second transducer, and includes the following steps:

[0032] - Generate a first electrical signal, apply the first electrical signal across the terminals of the first transducer, and thereby generate a first acoustic wave to directly move and remove the solid element;

[0033] - Generate a second electrical signal, apply the second electrical signal across the terminals of the second transducer, and thereby generate a second sound wave to move the liquid element.

[0034] The present invention also proposes the above-mentioned cleaning method, wherein the object is tilted and includes a first end and a second end. Due to the tilt of the object, the first end is lower than the second end. A first transducer is located on a first side of the object including the first end, and a second transducer is located on a second side of the object including the second end.

[0035] The present invention also proposes the above-mentioned cleaning method, which includes the following steps performed every day the cleaning method is implemented:

[0036] - During a first predefined period of time included in the daytime of the day, the first electrical signal is generated and applied across the terminals of the first transducer;

[0037] - During a second predefined period of time, which is either night or early morning of the day, the second electrical signal is generated and applied across the terminals of the second transducer.

[0038] The present invention also proposes the above-described cleaning method, which uses at least one transducer row comprising a plurality of transducers acoustically coupled to an object, and includes the step of applying a phase-synchronized electrical signal to the terminals of the transducers.

[0039] The present invention also proposes the above-mentioned cleaning method, which uses multiple transducer rows, each transducer row containing at least one transducer acoustically coupled to an object, and the cleaning method includes the step of sequentially applying electrical signals to the terminals of one or more transducers in each transducer row in a predefined order.

[0040] The present invention also proposes the above-mentioned cleaning method, wherein transducer rows extend sequentially along the length or width of an object to form a series of transducer rows; for each transducer row in the series of transducer rows, a predefined sequence includes applying an electrical signal across the terminals of one or more transducers in that transducer row, and then, after a certain period of time, applying an electrical signal across the terminals of one or more transducers in the next transducer row in the series of transducer rows.

[0041] The present invention also proposes the above-described cleaning method, wherein the time period is a predefined time period determined during the testing phase, which is a time period sufficient to remove a quantity of solid elements greater than a first predefined threshold from the surface of the object between the transducer row and the next transducer row or between the transducer row and the preceding transducer row in the series of transducer rows.

[0042] The present invention also proposes the above-mentioned cleaning method, which uses at least one third transducer and at least one fourth transducer acoustically coupled to the object, and includes the following steps:

[0043] - Generate a third electrical signal;

[0044] - Apply the third electrical signal across the terminals of the third transducer;

[0045] - This generates a third sound wave that propagates through the object between the third transducer and the fourth transducer;

[0046] -When the fourth transducer receives the third acoustic wave, it collects the fourth electrical signal generated by the fourth transducer;

[0047] - Analyze the fourth electrical signal to detect the presence of solid and / or liquid elements between the third and fourth transducers and / or assess the amount of such solid and / or liquid elements.

[0048] The present invention also proposes the above-mentioned cleaning method, which includes the step of analyzing the fourth electrical signal to assess the amount of liquid element between the third transducer and the fourth transducer, wherein the second electrical signal is generated and applied only when the amount of liquid element is greater than a second predefined threshold.

[0049] The present invention also proposes the above-mentioned cleaning method, which includes the step of analyzing the fourth electrical signal to assess the amount of solid elements between the third transducer and the fourth transducer, wherein the time period is such that: at the end of the time period, the amount of solid elements between the third transducer and the fourth transducer is less than a third predefined threshold.

[0050] The present invention also proposes an electrical control system designed to implement the above-described cleaning method.

[0051] The present invention also proposes the above-mentioned electrical control system, which includes at least one ASIC.

[0052] The present invention also proposes a cleaning device, which includes:

[0053] - At least one transducer designed for acoustic coupling with an object;

[0054] - Such as the electrical control system described above.

[0055] The present invention also proposes a photovoltaic panel comprising a protective plate and the aforementioned cleaning device, wherein the protective plate is an object acoustically coupled to at least one transducer.

[0056] The invention will be best understood from the following description of specific, non-limiting embodiments thereof.

[0057] Brief description of the attached figures

[0058] The accompanying drawings will be referenced, in which:

[0059] [ Figure 1 ] Figure 1 This is a perspective view of a photovoltaic panel, in which the transducer of the cleaning device according to the first embodiment can be seen.

[0060] [ Figure 2 ] Figure 2 Is with Figure 1 A similar view shows the various stacked layers of the photovoltaic panels;

[0061] [ Figure 3 ] Figure 3 The electrical control system and transducer are shown;

[0062] [ Figure 4 ] Figure 4 This illustrates the movement of solid elements under the direct action of sound waves;

[0063] [ Figure 5 ] Figure 5 This illustrates the movement of solid elements achieved through the movement of liquid elements;

[0064] [ Figure 6 ] Figure 6 The cleaning device is shown to operate in a day-night (or early morning) combination.

[0065] [ Figure 7 ] Figure 7 Is with Figure 1 A similar view shows the cleaning apparatus according to the second embodiment;

[0066] [ Figure 8 ] Figure 8 Is with Figure 1 A similar view shows the cleaning apparatus according to a third embodiment.

[0067] Detailed Description of the Invention

[0068] refer to Figure 1 and Figure 2 The photovoltaic panel 1 is supported by two legs 2a and 2b extending vertically from a first base 3a placed on the ground, and two legs 2c and 2d extending vertically from a second base 3b also placed on the ground.

[0069] Legs 2a and 2c are of the same length. Legs 2b and 2d are of the same length but shorter than legs 2a and 2c, thus the photovoltaic panel 1 is tilted. This tilted structure optimizes the orientation of the photovoltaic panel 1 relative to the direction of sunlight, thereby maximizing the efficiency of the photovoltaic panel 1.

[0070] The photovoltaic panel 1 comprises multiple stacked layers and a frame 4 (or base) forming the sidewalls of the photovoltaic panel 1. These stacked layers are assembled, for example, by a lamination process. The frame 4 can improve the rigidity of the photovoltaic panel 1 and enhance its mechanical strength, and can prevent water from penetrating between the stacked layers.

[0071] These stacked layers include, in particular, a protective plate 5, a layer 6 containing photovoltaic cells, and a rigid layer 7 (and may also include an intermediate layer not shown here).

[0072] Frame 4 is made of aluminum, for example.

[0073] The protective plate 5 is made of glass (tempered glass, laminated glass, etc.) or other transparent or translucent materials.

[0074] This plate 5 is referred to as the "protective plate," but as mentioned earlier, it is sometimes also called the "protective glass" or "glass."

[0075] Typically, the plate 5 mentioned here is the outer upper plate that constitutes the photovoltaic panel 1, that is, the upper plate that separates the outside and the inside of the photovoltaic panel 1.

[0076] Solid elements 8, such as sand, dust particles, soil, insects (such as mosquitoes), and bird droppings, may be present on the outer surface 9 of the protective panel 5. Especially in arid regions, large amounts of dust will accumulate on the photovoltaic panel 1.

[0077] The photovoltaic panel 1 includes a cleaning device that can clean the outer surface 9 of the protective panel 5.

[0078] refer to Figure 3 The cleaning device 10 includes at least one transducer 11 (in this embodiment, multiple transducers 11) and an electrical control system 12, which are acoustically coupled to the protection plate 5 of the photovoltaic panel 1.

[0079] All transducers 11 in this embodiment are identical. Herein and without limitation, transducer 11 is a thin-layer interdigitated comb transducer.

[0080] In this example, each transducer 11 includes a thin piezoelectric layer, a first electrode 14a, and a second electrode 14b. The electrodes are deposited on the piezoelectric layer, which itself is deposited on the outer surface 9 of the protective plate 5.

[0081] The first electrode 14a forms the first comb, while the second electrode 14b forms the second comb.

[0082] Each comb has a base and a row of fingers extending parallel to each other from the base. The first and second combs are interdigitated. The resonant frequency of transducer 11 depends on the spacing between the fingers.

[0083] The electrical control system 12 includes a main electrical module 15 and multiple elementary electrical modules 16. The main electrical module 15 is connected to all the elementary electrical modules 16.

[0084] The main electrical module 15 is included in the housing 17, which in this embodiment is located below and fixed to the rigid layer 7.

[0085] Of course, housing 17 can also be placed in other locations. Components of the main electrical module 15 can also be included in the protective plate 5, and correspondingly, the basic electrical module 16 can also be placed inside the housing. The protective plate 5 is thus "instrumented" to implement the invention.

[0086] The main electrical module 15 is designed to supply electrical energy generated by the photovoltaic panel 1 to the basic electrical module 16 and to control the basic electrical module 16.

[0087] An input voltage Ve (DC) generated by the photovoltaic cells in layer 6 is applied as input to the main electrical module 15. In this case, the main electrical module 15 includes a DC / DC converter 18, which generates an output voltage Vs suitable for the operation of the basic electrical module 16 from the input voltage Ve. The main electrical module 15 includes a processing component 19 (e.g., a microcontroller, processor, field-programmable gate array (FPGA), application-specific integrated circuit (ASIC), etc.) that generates control signals Sc for driving the basic electrical module 16. The main electrical module 15 also includes a clock component 20. Therefore, the main electrical module 15 transmits the control signals Sc and the clock signal CLK to the basic electrical module 16, the functions of which will be explained below.

[0088] Each basic electrical module 16 includes a processing component (specifically an ASIC 22) and is associated with a transducer 11.

[0089] Here, each ASIC 22 includes a power conversion unit 23, an impedance matching unit 24, and an amplification unit 25.

[0090] The power conversion unit 23 is powered by the output voltage Vs generated by the main electrical module 15 and generates an electrical signal Se (AC, such as a square wave or sine wave) with a frequency that is the resonant frequency of the transducer 11.

[0091] Impedance matching unit 24 optimizes power transmission between basic electrical module 16 and transducer 11 by limiting power reflection.

[0092] Amplification unit 25 amplifies the electrical signal Se before applying it to the terminals of transducer 11. The amplified electrical signal Se enables transducer 11 to generate surface acoustic waves or Lamb waves, as described below, whose frequency and amplitude allow for the movement of solid and liquid elements.

[0093] In this article, "transducer terminal" refers to the end of the comb base of the transducer. The term "apply an electrical signal across the transducer terminal" means either applying a voltage across the terminal (in which case the signal is a voltage signal) or causing current to flow between the terminals (in which case the signal is a current signal).

[0094] On average, the cleaning device 10 consumes less than 1% (or even less than 0.5%) of the total power generated by the photovoltaic panel 1 per day.

[0095] The working principle of the cleaning device 10 will be explained below.

[0096] First refer to Figures 4 to 5 Considering only a single transducer 11.

[0097] Solid element 8 (in this case, sand particles) is present on the outer surface 9 of the protective plate 5.

[0098] The main electrical module 15 transmits a control signal Sc to the basic electrical module 16 associated with the transducer 11 to activate the transducer 11.

[0099] After receiving the control signal Sc, the basic electrical module 16 generates an electrical signal Se and applies the electrical signal Se to the terminals of the transducer 11.

[0100] The transducer 11 thus generates an acoustic wave that propagates through the protective plate 5. This acoustic wave is a surface wave (e.g., a Rayleigh wave or a Love wave) or a Lamb wave.

[0101] Here, the (fundamental) frequency of the sound wave is between 1 MHz and 100 MHz, advantageously between 10 MHz and 40 MHz, and preferably between 18 MHz and 22 MHz.

[0102] If the thickness of the protective plate 5 is greater than the wavelength of the sound wave, then the sound wave is a surface acoustic wave. Otherwise, it is a Lamb wave.

[0103] The characteristic of this sound wave is that, under its action, solid elements will be moved on the outer surface 9 of the protective plate 5 so that they can be removed from the surface.

[0104] The movement of solid elements can be achieved in two ways.

[0105] like Figure 4 As shown, when only solid element 8 exists on the surface, solid element 8 is directly moved and removed by the force generated by sound waves and transmitted through the contact between the surface and solid element 8.

[0106] Figure 4 The left-hand view shows the transducer 11 and solid element 8 before the electrical signal Se is generated and applied across the terminals of the transducer 11.

[0107] Figure 4 The intermediate view shows the transducer 11 and solid element 8 when an electrical signal Se is generated and applied across the terminals of the transducer 11.

[0108] The sound wave propagates along the propagation direction and passes through the protective plate 5 in the first direction (sense) S1.

[0109] Under the influence of the sound waves, the solid element 8 moves on the outer surface 9 of the protective plate 5 along the propagation direction but in a second direction S2 opposite to the first direction S1. The movement of the solid element 8 in the direction opposite to the propagation direction of the sound waves is a phenomenon characteristic of the interaction between surface acoustic waves or Lamb waves propagating through an object and solid elements present on the surface of that object. This phenomenon was observed in all tests conducted during the development of the cleaning device described herein. These tests, in particular, used sound waves with frequencies of 17.6 MHz and 19.6 MHz, and sand particles (typically between 100 μm and 2 mm in diameter) and plastic particles (e.g., polyamide 11; typically 30 μm in diameter).

[0110] Figure 4 The right-hand view shows that solid element 8 has been removed from the surface “in front” of the transducer (i.e., the surface outside the transducer and located on one side of the finger) (typically within 10 seconds).

[0111] When liquid elements 27, such as water droplets, are present on the outer surface 9 of the protective plate 5, sound waves induce nonlinear acoustic phenomena such as acoustic flow and / or radiation pressure. Under the influence of these phenomena, the liquid elements 27 move. At this time, the solid elements 8 are carried away by the liquid elements 27, thereby achieving movement and removal.

[0112] Figure 5 The left-hand view shows: transducer 11, solid element 8, and liquid element 27 before the electrical signal Se is generated and applied across the terminals of transducer 11.

[0113] Figure 5 The intermediate view shows the transducer 11, solid element 8, and liquid element 27 when an electrical signal Se is generated and applied across the terminals of the transducer 11.

[0114] At this time, under the action of the sound wave, the liquid element 27 moves along the direction of sound wave propagation and in the same direction S on the outer surface 9 of the protective plate 5, and drives the solid element 8 to move along the same direction and direction S.

[0115] Figure 5 The right-side view shows that solid element 8 has been carried away by liquid element 27 and cleared from the surface in front of the transducer.

[0116] It is important to note that this effect cannot be achieved in the sliding state of the droplet; it can only be achieved in a forced state where movement is induced by sound waves (otherwise, the droplet would be blocked by impurities and unable to move).

[0117] Now back Figure 1

[0118] According to the first embodiment, the cleaning device 10 has a transducer including at least one first transducer 11a (in this case, multiple first transducers 11a) and at least one second transducer 11b (in this case, multiple second transducers 11b).

[0119] Here, the first transducer 11a constitutes the first transducer row 30 of the first transducer 11a (therefore, "first transducer 11a" in this document refers to all the transducers in the first transducer row 30). The second transducer 11b constitutes the second transducer row 31 of the second transducer 11b (therefore, "second transducer 11b" in this document refers to all the transducers in the second transducer row 31). The transducer rows 30 and 31 extend parallel to the width direction of the protective plate 5 (and thus the photovoltaic panel 1).

[0120] The protective plate 5 includes a first end 32 and a second end 33. Since the photovoltaic panel 1 is tilted, the first end 32 is lower than the second end 33.

[0121] The first transducer row 30 of the first transducer 11a is located on the first side of the protective plate 5 including the first end 32, and the second transducer row 31 of the second transducer 11b is located on the second side of the protective plate 5 including the second end 33.

[0122] For each first transducer 11a in the first transducer row 30, the electrical control system 12 generates a first electrical signal and applies the first electrical signal across the terminals of the first transducer 11a, thereby generating a first acoustic wave 34a to directly move and remove the solid element 8.

[0123] Similarly, for each of the second transducers 11b in the second transducer row 31, the electrical control system 12 generates a second electrical signal and applies the second electrical signal across the terminals of the second transducer 11b, thereby generating a second acoustic wave 34b to move the liquid element 27.

[0124] When it is determined a priori that only solid element 8 can exist on the outer surface 9 of the protective plate 5 (i.e., during the daytime), it is advantageous to use the first transducer 11a.

[0125] When it is pre-determined that liquid elements 27 may be present on the outer surface 9 of the protective plate 5 (i.e., mainly during nighttime or early morning hours), it is advantageous to use the second transducer 11b. These liquid elements are mainly water droplets, more specifically, condensation from dew or raindrops.

[0126] Therefore, each day the cleaning device 10 is activated, the electrical control system 12 implements the cleaning method: during a first predefined period of daytime (e.g., 9:00 AM to 7:00 PM), a first electrical signal is generated and applied across the terminals of the first transducer 11a; during a second predefined period of nighttime or early morning (e.g., 5:00 AM to 7:00 AM), a second electrical signal is generated and applied across the terminals of the second transducer 11b. During the second predefined period of nighttime or early morning (e.g., between 5:00 AM and 7:00 AM), the electrical control system 12 generates a second electrical signal and applies it across the terminals of the second transducer 11b.

[0127] Therefore, during the daytime, the sound-induced vibrations cause the solid element 8 to detach from the surface and move towards the bottom of the photovoltaic panel 1. At night (or in the early morning), these vibrations cause condensate water to move through a nonlinear acoustic effect, thereby cleaning the surface of the photovoltaic panel 1. Thus, this method combines dry cleaning during the day with cleaning achieved at night through the movement of condensate water.

[0128] It should be noted that since the electrical control system 12 is powered by the photovoltaic cells of the photovoltaic panel 1, the second transducer row 31 is preferably operated during the early morning hours. However, the main electrical module 15 can also be equipped with batteries that are charged during the day so that the cleaning device 10 can operate at night.

[0129] This combination model has significant advantages.

[0130] refer to Figure 6 During the daytime (left view), when there is no liquid element 27 on the outer surface 9 of the protective plate 5 (based on prior judgment), the first sound wave 34a generated by the first transducer 11a propagates to the upper part of the photovoltaic plate 1, thereby causing the solid element 8 to move downward.

[0131] This force, combined with gravity, can effectively move and remove solid elements from the surface above the first transducer row 30.

[0132] During nighttime or early morning hours (right-side view), when liquid element 27 is present, the second acoustic wave 34b generated by the second transducer 11b propagates downwards towards the lower part of the photovoltaic panel 1, causing the liquid element 27 to move downwards. Similarly, this force, combined with gravity, effectively pushes the liquid element 27 downwards, thereby effectively removing the solid element 8 from the outer surface 9 of the protective plate 5.

[0133] The design utilizing these combined effects is ingenious. More specifically, as mentioned earlier, the "adhesion effect" caused by condensation is often a problem in the cleaning process. This invention overcomes the inherent cognitive biases of those skilled in the art by utilizing condensate.

[0134] It should be noted that it is not necessary to completely remove all solid elements 8 from the outer surface 9; a small amount of solid elements 8 may remain on the protective plate 5, especially near the edges and / or the surface areas of the transducer. These residual elements have a minimal impact on the efficiency of the photovoltaic panel 1.

[0135] Advantageously, the electrical control system 12 applies a phase-synchronized first electrical signal to the terminals of the first transducer 11a. This increases the amplitude of the first sound wave while keeping the amplitude of the first electrical signal constant. Similarly, the electrical control system 12 applies a phase-synchronized second electrical signal to the terminals of the second transducer 11b.

[0136] To generate a phase-synchronized first electrical signal (or a phase-synchronized second electrical signal), the basic electrical module 16 associated with the first transducer 11a (or the basic electrical module 16 associated with the second transducer 11b) uses the clock signal CLK transmitted by the main electrical module 15, so all basic electrical modules are synchronized based on the same clock.

[0137] Therefore, in the first embodiment of the cleaning device, the transducer row at the bottom (first transducer row 30) is used to move and remove the solid element 8, and the transducer row at the top (second transducer row 31) is used to move the liquid element 27, thereby simultaneously removing the solid element 8.

[0138] The photovoltaic panel 1 includes a first end (corresponding to the first end 32 of the protection panel 5) and a second end (corresponding to the second end 33 of the protection panel 5).

[0139] Advantageously, the upper surface of the photovoltaic panel 1 is planar and without discontinuous areas, at least at the first end (bottom) of the photovoltaic panel 1.

[0140] Therefore, the design of photovoltaic panel 1 (at least its lower part) should especially avoid the presence of edge protrusions.

[0141] In this embodiment, the frame 4 includes an upper surface 36 extending along the contour of the protective plate 5. At least at the first end of the photovoltaic panel 1, the upper surface 36 of the frame 4 is coplanar with the outer surface 9 of the protective plate 5.

[0142] This smooth surface ensures that solid element 8 (and liquid element 27) will not remain on photovoltaic panel 1 when it is removed.

[0143] It should be noted that a completely flat surface can also be achieved through other structural designs. For example, frame 4 can be omitted. Alternatively, protective plate 5 can cover and fix the upper surface 36 of frame 4 (e.g., by adhesive). In both cases, the outer surface 9 of protective plate 5 extends to the entire upper surface of photovoltaic panel 1.

[0144] Now for reference Figure 7The second embodiment of the cleaning device will be described.

[0145] The cleaning device includes multiple transducer rows, each containing at least one transducer acoustically coupled to the protection plate 5.

[0146] Specifically, in this case, the cleaning device includes six rows of transducers.

[0147] These six transducer rows include three first transducer rows 30a, 30b, and 30c of the first transducer 11a (each transducer row generates an upward-propagating first sound wave), and three second transducer rows 31a, 31b, and 31c of the second transducer (each transducer row generates a downward-propagating second sound wave).

[0148] Therefore, in this article, "first transducer 11a" refers to all transducers in the first transducer rows 30a, 30b, and 30c, and "second transducer 11b" refers to all transducers in the second transducer rows 31a, 31b, and 31c.

[0149] The first transducer rows 30a, 30b, and 30c are arranged alternately with the second transducer rows 31a, 31b, and 31c on the photovoltaic panel (i.e., the transducer row adjacent to the first transducer row is the second transducer row, and vice versa). The highest transducer row on the photovoltaic panel 1 is the second transducer row 31a, and the rows following downwards are the first transducer row 30a, the second transducer row 31b, and so on.

[0150] The first transducer rows 30a, 30b, and 30c extend sequentially along the length of the protective plate 5, forming the first series of transducer rows 38.

[0151] The second transducer rows 31a, 31b, and 31c extend sequentially along the length of the protective plate 5 to form the second series of transducer rows 39.

[0152] First, the first transducer rows 30a, 30b, and 30c will be explained.

[0153] The electrical control system 12 applies a first electrical signal to the terminal of the first transducer 11a of each first transducer row 30a, 30b, and 30c in a first predefined sequence.

[0154] For each first transducer row, the first predefined sequence is: apply a first electrical signal to the terminal of the first transducer 11a in the first transducer row, and then, after a certain period of time, apply a first electrical signal to the terminal of the first transducer in the next first transducer row in the first series of transducer rows 38.

[0155] Therefore, each of the first transducer rows is activated sequentially. The first transducer 11a thus produces constructive interference.

[0156] For example, the first transducer row 30a, which is the highest position on photovoltaic panel 1, is activated first.

[0157] After a certain period of time, the first transducer row 30b is activated. After another certain period of time, the first transducer row 30c is activated.

[0158] If multiple loops are required, the transducer rows after the first transducer row 30c can be defined as the first transducer row 30a.

[0159] The "certain time period" corresponding to different first transducer rows may vary.

[0160] The "certain time period" refers to the time interval between the activation of two adjacent first transducer rows, such as a predefined time period determined during the testing phase. In this paper, "testing phase" refers to any stage before the photovoltaic panel 1 (or at least the cleaning device) is put into use: the testing phase can be conducted in a laboratory, factory, or on-site. Therefore, this design utilizes previously acquired knowledge about the typical motion patterns of solid-state element 8.

[0161] The predefined time period is usually 3 seconds, but the predefined time period may vary for different transducer rows.

[0162] For each first transducer row, the predefined time period is a time period sufficient to remove a quantity of solid elements 8 greater than a first predefined threshold from the surface area on the outer surface 9 of the protective plate located between the first transducer row and the previous first transducer row.

[0163] For example, after activating the first transducer row 30b, it is necessary to wait for the solid element 8 on the surface between the first transducer rows 30a and 30b to be cleared before activating the first transducer row 30c.

[0164] When determining the predefined time period associated with the first transducer row 30a, for example, the position of the previous first transducer row can be considered to correspond to the second end 33 of the protection plate 5.

[0165] The first predefined threshold is, for example, 50%. Therefore, after this certain period of time, it can be considered that the cleaning device, through the action of each first transducer row, has removed at least 50% of the solid elements between the first transducer row and the previous first transducer row.

[0166] As previously mentioned, the first transducer row 30 is preferably activated during the daytime.

[0167] The second transducer row 31 is activated during the night or early morning hours.

[0168] The electrical control system 12 also applies a second electrical signal to the terminals of the second transducers 11b of each second transducer row 31 in a second predefined sequence.

[0169] For each second transducer row 31, the second predefined sequence is: apply a second electrical signal to the terminal of the second transducer 11b of the second transducer row, and then, after a certain period of time, apply a second electrical signal to the terminal of the second transducer 11b of the next second transducer row in the second group of transducer rows.

[0170] Therefore, each of the second transducer rows is activated sequentially.

[0171] The second transducer row 31a, which is the highest on photovoltaic panel 1, is activated first.

[0172] After a certain period of time, the second transducer row 31b is activated. After another certain period of time, the second transducer row 31c is activated.

[0173] If multiple loops are required, the transducer row after the second transducer row 31c can be defined as the second transducer row 31a.

[0174] The specific time periods may vary, depending on the transducer rows.

[0175] The "certain time period" defined for the second transducer row may differ from the "certain time period" defined for the first transducer row.

[0176] For each second transducer row, the predefined time period is a sufficient time period during which a solid element exceeding a first predefined threshold can be removed from the surface region on the outer surface located between the second transducer row and the next second transducer row (in this case, the next one, not the previous one) by liquid elements.

[0177] When determining the predefined time period associated with the second transducer row 31c, the position of the next second transducer row can be considered to correspond to the first end 32 of the protection plate 5 (corresponding to the first end 32 of the photovoltaic panel 1).

[0178] The first predefined threshold is, for example, 50%. Therefore, after this certain period of time, it can be considered that the cleaning device, through the action of each second transducer row, has removed at least 50% of the solid elements between the second transducer row and the next second transducer row.

[0179] Of course, other arrangements of the transducer array can also be used.

[0180] For example, in Figure 8In the third embodiment of the cleaning device 10 shown, three first transducer rows 30a, 30b, and 30c are located at the lower part of the photovoltaic panel 1, while three second transducer rows 31a, 31b, and 31c are located at the upper part of the photovoltaic panel 1.

[0181] The first predefined sequence of the first group of transducer rows 38 and the second predefined sequence of the second group of transducer rows 39 can adopt the same settings as described above.

[0182] Therefore, the generated sound waves can be used to directly move solid element 8 or liquid element 27, thereby achieving the removal of solid element 8.

[0183] Sound waves can also be used to detect the presence of these elements and even assess the amount of these elements on the outer surface 9 of the protective plate 5. Therefore, on the one hand, the state of contamination of the photovoltaic panel 1 by the solid element 8 can be determined, and on the other hand, the amount of condensate on the photovoltaic panel 1 can be determined.

[0184] For this purpose, at least one transmitting transducer and at least one receiving transducer are used.

[0185] The transmitting transducer emits sound waves, which travel a predefined path through the protective plate 5 before being received by the receiving transducer. By analyzing the electrical signal generated by the receiving transducer, the presence of an element can be detected, and even the quantity of the element can be assessed.

[0186] Therefore, the cleaning device 10 includes at least one third (emitting) transducer 11c and at least one fourth (receiving) transducer 11d that are acoustically coupled to the protection plate 5.

[0187] The basic electrical module 16 associated with the third transducer 11c generates a third electrical signal and applies the third electrical signal across the terminals of the third transducer 11c. This generates a third (detection) sound wave that propagates through the protective plate 5 between the third transducer 11c and the fourth transducer 11d.

[0188] The basic electrical module 16 associated with the fourth transducer 11d acquires the fourth electrical signal generated by the fourth transducer 11d when it receives the third acoustic wave. This basic electrical module 16 analyzes the fourth electrical signal to detect the presence and / or quantity of solid element 8 and / or liquid element 27 between the third transducer 11c and the fourth transducer 11d. For example, the analysis of the fourth electrical signal may include: comparing its amplitude to one or more predefined thresholds, performing phase measurements, detecting zero crossings, analyzing specific lobes, etc.

[0189] Of course, one or more third transducers 11c may be one or more of the first transducers 11a described above, or one or more of the second transducers 11b described above. Similarly, one or more fourth transducers 11d may be one or more of the first transducers 11a described above, or one or more of the second transducers 11b described above.

[0190] However, this is not necessary; transducers 11c and 11d, which are specifically designed for detection, can also be installed.

[0191] The ASIC 22 of the basic electrical module 16 associated with the fourth transducer 11d (specifically, the ASIC 22 of all basic electrical modules 16) includes a detection module 40 (see Figure 3 This module acquires and analyzes a fourth electrical signal to detect the presence of solid and / or liquid elements and / or assess their quantity.

[0192] Now back Figure 6

[0193] In the right-hand view, the first transducer, which also serves as the third transducer 11c, can be seen.

[0194] It can be seen that it also serves as the second transducer of the fourth transducer 11d.

[0195] The usage of the third transducer 11c and the fourth transducer 11d is as follows.

[0196] During the nighttime (or early morning) period, the main electrical module 15 controls the basic electrical module 16 associated with the third transducer 11c to emit a third (detection) sound wave. The third transducer 11c generates the third sound wave, which is received by the fourth transducer 11d.

[0197] The basic electrical module 16 associated with the fourth transducer 11d analyzes the fourth electrical signal generated by the fourth transducer 11d to assess the amount of liquid element 27 between the third transducer 11c and the fourth transducer 11d, and transmits the detection signal Sd (see main electrical module 15) to the main electrical module 15. Figure 3 ).

[0198] Subsequently, the main electrical module 15 controls the basic electrical module 16 associated with the second transducer 11b of the second transducer row 31 to generate a second electrical signal and apply the second electrical signal to the terminals of the second transducer 11b of the second transducer row 31 only when the amount of liquid element 27 is greater than a second predefined threshold.

[0199] For example, the amount of liquid element 27 is the number of water droplets on a rectangular surface 41, the length of which is the distance between the third transducer 11c and the fourth transducer 11d, and the width of which is the width of these transducers. A second predefined threshold is, for example, equal to 100 droplets.

[0200] This ensures that the second transducer 11d will only be activated when there is a sufficient number of water droplets on the outer surface 9 of the protective plate 5.

[0201] Now go to Figure 7 .

[0202] It can be seen that the second transducer of the second transducer row 31a also serves as the third transducer 11c.

[0203] It can be seen that the first transducer in the first transducer row 30a also serves as the fourth transducer 11c.

[0204] It can be seen that the first transducer in the first transducer row 30b also serves as the fourth transducer 11d.

[0205] It can be seen that the first transducer in the first transducer row 30c also serves as the fourth transducer 11d.

[0206] As previously described, for each first transducer row 30 in sequence and according to a predefined order, a first electrical signal is applied to the terminal of the first transducer 11a of that first transducer row 30.

[0207] For each first transducer row, the predefined sequence is: apply a first electrical signal to the terminal of the first transducer of the first transducer row, and then, after a certain period of time, apply a first electrical signal to the terminal of the first transducer of the next transducer row.

[0208] For each first transducer row 30 (i.e., 30a, 30b, or 30c), when the first transducer row is activated, the main electrical module 15 in this embodiment periodically or continuously controls the third transducer 11c to emit a third acoustic wave. The fourth transducer 11d of the first transducer row 30 receives the third acoustic wave. The basic electrical module 16 associated with the fourth transducer 11d analyzes the fourth electrical signal to assess the amount of solid element 8 between the third transducer 11c and the fourth transducer 11d.

[0209] The “certain time period” ensures that at the end of the time period, the amount of solid element 8 between the third transducer and the fourth transducer is less than the third predefined threshold.

[0210] The first transducer row 30c will be taken into account, for example. The amount of solid element 8 is, for example, the number of particles on the rectangular surface 42, the length of which is the distance between the third transducer 11c and the fourth transducer 11d of the first transducer row 30c, and the width of which is the width of these transducers. A third predefined threshold is, for example, equal to 1000 particles. This operation is repeated sequentially for each first transducer row 30.

[0211] For each first transducer row 30, before switching to the next first transducer row, ensure that the surface of the outer surface 9 of the protective plate 5 located above the first transducer row is thoroughly cleaned by the first sound wave emitted by the first transducer row.

[0212] For example, in Figure 7 In the illustrated structure, a third transducer 11c can also be disposed on the second transducer row 31a, and a fourth transducer 11d can be disposed on the first transducer row 30a (or vice versa); a third transducer 11c can be disposed on the second transducer row 31b, and a fourth transducer 11d can be disposed on the first transducer row 30b (or vice versa); a third transducer 11c can be disposed on the second transducer row 31c, and a fourth transducer 11d can be disposed on the first transducer row 30c (or vice versa). This structure allows each pair of transducer rows (31a and 30a, 31b and 30b, 31c and 30c) to have a pair of oppositely disposed and closely spaced third and fourth transducers. This structure can efficiently and accurately detect the presence of solid and / or liquid elements between two adjacent transducer rows, and assess their quantity.

[0213] Of course, whether Figure 1 , Figure 7 still Figure 8 The structure shown is used to move the acoustic waves of solid element 8 or liquid element 27, and can also be used to perform detection.

[0214] For example, in Figure 1 In the structure shown, the first transducer 11a can be used as a transmitting transducer (which therefore acts as the third transducer 11c), and the second transducer 11b can be used as a receiving transducer (which therefore acts as the fourth transducer 11d).

[0215] During the daytime, a first sound wave is emitted to remove solid elements. A third sound wave is then emitted to check the effectiveness of the cleaning process. If the cleaning is effective, it stops. If ineffective, the first sound wave is emitted again.

[0216] A third sound wave can also be emitted for periodic detection purposes until a large amount of solid element 8 is detected. The first sound wave is then emitted for cleaning.

[0217] Therefore, it can be concluded that the first sound wave can be used as the third sound wave, and vice versa. Similarly, the second sound wave can be used as the third sound wave, and vice versa.

[0218] The first electrical signal and the second electrical signal may be the same, but are not required to be the same. The first electrical signal and / or the second electrical signal may also be the same as the third electrical signal, but are again not required to be the same. In particular, when the third electrical signal is only used for detection, its level may be lower than the levels of the first and second electrical signals used for moving solid element 8 and liquid element 27.

[0219] Of course, the present invention is not limited to the described embodiments, but includes any variations as defined in the claims that come into the field of the invention.

[0220] This cleaning method is not limited to cleaning the outer surface of photovoltaic panel protective plates; it can also be used to clean the surfaces of other types of objects. This invention can be applied to any object capable of propagating surface acoustic waves or Lamb waves.

[0221] The object may include, for example, the surface of an optical device such as a camera or viewfinder.

[0222] This cleaning method is particularly advantageous for devices that require light capture to function, and where the light must pass through a transparent or translucent object before being captured by one or more light-capturing components.

[0223] At this point, the cleaning method can be used to clean the inner or outer surface of the object.

[0224] For photovoltaic panels, the component in question is the photovoltaic cell. For cameras or viewfinders, the component is the light sensor.

[0225] The one or more transducers may differ from those described above. Any type of transducer capable of generating surface acoustic waves or Lamb waves may be used.

[0226] When the surface of a piezoelectric object is cleaned, the transducer electrodes can be applied directly to the piezoelectric object.

[0227] Angle transducer technology can be used. A transducer and a shoe-shaped component located between the transducer and the surface to be cleaned are used. The shoe-shaped component tilts the transducer's axis so that it forms an angle with the normal to the surface to be cleaned. Bulk acoustic waves propagate within the shoe-shaped component. This specific angle is defined by the Snell-Cartesian law so that the bulk acoustic waves are converted into surface acoustic waves at the interface between the shoe-shaped component and the surface to be cleaned.

[0228] Other systems that convert bulk acoustic waves into surface acoustic waves can also be used.

[0229] The transducer does not necessarily have to be placed on the surface where the surface to be cleaned is located; the transducer can also be placed on the surface opposite the surface to be cleaned (especially in the case of plate-shaped objects).

[0230] The architecture of an electrical control system can, of course, differ from the description above.

[0231] For example, it is possible to equip the entire panel with a single electrical module. This single electrical module would be connected to all the transducers and perform all the functions described here: generating electrical signals, analyzing signals for detection, and so on.

[0232] For example, this single electrical module may contain an ASIC (or FPGA) and a power amplifier.

[0233] It is also possible to have a basic electrical module for each transducer.

[0234] The main module and / or basic module, or a single electrical module, may also include other types of processing components besides ASICs or FPGAs, such as "general purpose" processors, signal processing dedicated processors (i.e., digital signal processors DSPs), microcontrollers, etc.

[0235] At this time, the main module and / or basic module, or a single electrical module, includes one or more memories (especially one or more non-volatile memories) connected to or integrated within the processing component. At least one of these memories constitutes a computer-readable storage medium storing at least one computer program containing instructions to cause the processing component to perform at least some steps of the cleaning method.

[0236] In a system with multiple photovoltaic panels, a single photovoltaic panel can be used to detect the presence of liquid or solid elements and transmit the information related to that detection to the other photovoltaic panels. The transmission method can be any wired or wireless communication means.

[0237] The arrangement of the transducers may differ from the description above.

[0238] The cleaning device can be operated using a single transducer. Each transducer row may contain only one transducer. There may be only one series of transducer rows. For each series of transducer rows containing multiple transducer rows, the transducer rows may extend sequentially along the width direction (not the length direction) of the object.

[0239] In a transducer array, not all transducers are necessarily oriented in the same way. A transducer array may also include transducers specifically designed to detect the presence of solid or liquid elements.

[0240] In a transducer array, transducers can be connected in parallel (or even some in series and others in parallel).

[0241] Transducers can be grouped together, rather than forming transducer rows.

[0242] The transducer used to perform the detection can be positioned differently from other transducers. The sound waves used for detection can also be emitted in the width direction of the object.

[0243] The detection function does not necessarily require the use of a transducer. The cleaning function can be started automatically, for example, at fixed intervals (such as daily), without prior detection.

Claims

1. A cleaning method for cleaning solid elements (8) that may be present on the surface of an object (5), said solid elements (8) such as sand or dust particles, said cleaning method using at least one transducer (11) acoustically coupled to said object, and comprising the following steps: - Generate an electrical signal (Se); - Apply the electrical signal across the terminals of the transducer; - This generates sound waves (34a, 34b) that propagate through the object, the sound waves being surface waves or Lamb waves, and under the action of the sound waves, the solid element is moved on the surface of the object to be removed from the surface.

2. The cleaning method as described in claim 1, characterized in that, The frequency of the sound waves is between 1 MHz and 100 MHz.

3. The cleaning method as described in any one of the preceding claims, characterized in that, The solid element (8) is directly moved and removed by the force generated by the sound waves and transmitted through the contact between the surface of the object and the solid element.

4. The cleaning method as described in claim 3, characterized in that, The sound wave propagates through the object along the propagation direction and in a first direction (S1), and under the action of the sound wave, the solid element moves on the surface of the object along the propagation direction but in a second direction (S2) opposite to the first direction.

5. The cleaning method as described in any one of the preceding claims, characterized in that, When the liquid element (27) is present on the surface of the object, the sound waves induce nonlinear acoustic phenomena of acoustic flow and / or radiation pressure, thereby moving the liquid element.

6. The cleaning method as described in claims 3 and 5, characterized in that, Using at least one first transducer (11a) and at least one second transducer (11b), the cleaning method includes the following steps: - Generate a first electrical signal, apply the first electrical signal across the terminals of the first transducer, and thereby generate a first acoustic wave to directly move and clear the solid element (8); - Generate a second electrical signal, apply the second electrical signal across the terminals of the second transducer, and thereby generate a second acoustic wave to move the liquid element (27).

7. The cleaning method as described in claim 6, characterized in that, The object (5) is tilted and includes a first end (32) and a second end (33). Due to the tilt of the object, the first end is lower than the second end. The first transducer is located on the first side of the object containing the first end, while the second transducer is located on the second side of the object containing the second end.

8. The cleaning method as described in claim 6 or 7, characterized in that, This includes the following steps performed every day while implementing the cleaning method described: - During a first predefined period of time included in the daytime of the day, the first electrical signal is generated and applied across the terminals of the first transducer (11a); - During a second predefined period of time, including the night or early morning of the day, the second electrical signal is generated and applied across the terminals of the second transducer (11b).

9. The cleaning method as described in any one of the preceding claims, characterized in that, Using at least one transducer row (30, 31) comprising a plurality of transducers acoustically coupled to the object, and including the step of applying a phase-synchronized electrical signal to the terminals of the transducers.

10. The cleaning method as described in any one of the preceding claims, characterized in that, Using multiple transducer rows (30a, 30b, 30c, 31a, 31b, 31c), each transducer row containing at least one transducer acoustically coupled to the object, the cleaning method includes the step of sequentially applying electrical signals to the terminals of one or more transducers in each transducer row in a predefined order.

11. The cleaning method as described in claim 10, characterized in that, The transducer rows extend sequentially along the length or width of the object to form a series of transducer rows (38, 39). For each of the series of transducer rows, the predefined sequence includes applying the electrical signal across the terminals of one or more transducers in the transducer row, and then, after a certain period of time, applying the electrical signal across the terminals of one or more transducers in the next transducer row in the series of transducer rows.

12. The cleaning method as described in claim 11, characterized in that, The specified time period is a predefined time period determined during the testing phase. The predefined time period is a time period sufficient to remove an amount of solid-state elements greater than a first predefined threshold from the surface of the object between the transducer row and the next transducer row or between the transducer row and the preceding transducer row in the series of transducer rows.

13. The cleaning method as described in any one of the preceding claims, characterized in that, The cleaning method utilizes at least one third transducer (11c) and at least one fourth transducer (11d) acoustically coupled to the object, and includes the following steps: - Generate a third electrical signal; - Apply the third electrical signal across the terminals of the third transducer; - This generates a third sound wave that propagates through the object between the third transducer and the fourth transducer; -When the fourth transducer receives the third acoustic wave, it acquires the fourth electrical signal generated by the fourth transducer; - Analyze the fourth electrical signal to detect the presence of solid element (8) and / or liquid element (27) between the third transducer and the fourth transducer and / or assess the amount of solid element (8) and / or liquid element (27).

14. The cleaning method as described in claims 6 and 13, characterized in that, The method includes the step of analyzing the fourth electrical signal to assess the amount of liquid element between the third and fourth transducers, wherein the second electrical signal is generated and applied only when the amount of liquid element is greater than a second predefined threshold.

15. The cleaning method as described in claims 11 and 13, characterized in that, The step includes analyzing the fourth electrical signal to assess the amount of solid elements between the third and fourth transducers, wherein the time period is such that at the end of the time period, the amount of solid elements between the third and fourth transducers is less than a third predefined threshold.

16. An electrical control system (12) designed to implement the cleaning method as described in any of the preceding claims.

17. The electrical control system as described in claim 16, characterized in that, Includes at least one ASIC (22).

18. A cleaning device (10), comprising: - At least one transducer (11) designed for acoustic coupling with an object; - Electrical control system (12) as described in any one of claims 16 or 17.

19. A photovoltaic panel (1) comprising a protective plate (5) and a cleaning device (10) as claimed in claim 18, wherein the protective plate (5) is an object acoustically coupled to the at least one transducer.

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