Methods and systems for protecting a surface from biofouling

Abstract

An anti-fouling lighting system is used to protect the surface (16) from biofouling when the surface (16) is submerged in water. A non-contact water sensor (60) is used to sense water thereby to detect whether the light source arrangement (26) or a portion of the light source arrangement (26) is submerged in water. The light source arrangement (26) or the portion of the light source arrangement (26) is controlled according to the output of the water sensor (60).

Description

Technical Field

[0001] The present disclosure relates to methods for preventing fouling of surfaces or what is commonly referred to as antifouling, and to devices for performing these methods. The present disclosure specifically relates to methods and devices for antifouling of the hulls of ships. Background Art

[0002] Biofouling or biological fouling is the accumulation of microorganisms, plants, algae, and / or animals on a surface. The types of biofouling organisms are highly diverse and far exceed the attachment of barnacles and seaweeds. By some estimates, over 1700 species, including more than 4000 organisms, are responsible for biofouling. Biofouling is divided into microscopic fouling, including biofilm formation and bacterial adhesion, and macroscopic fouling, which is the attachment of larger organisms. Due to the different chemistries and biologies that determine what prevents organisms from depositing, these organisms are also classified as hard fouling types or soft fouling types.

[0003] Calcareous (hard) fouling organisms include barnacles, encrusting bryozoans, mollusks, polychaete worms, and other tube worms, as well as zebra mussels. Examples of non-calcareous (soft) fouling organisms are seaweeds, leeches, algae, and biofilm "slime". These organisms together form fouling communities.

[0004] In several cases, biofouling causes serious problems. Machinery stops working, water inlets become blocked, and the hulls of ships suffer increased drag. Thus, the subject of antifouling, the process of eliminating or preventing fouling formation, is well known.

[0005] In industrial processes, biocides can be used to control biofouling. In less controlled environments, coatings using pesticides, heat treatment, or energy pulses are used to kill or repel organisms. Non-toxic mechanical strategies for preventing organisms from attaching include selecting materials or coatings with smooth surfaces, or creating nanoscale surface topologies similar to shark or dolphin skin that provide only weak anchor points.

[0006] For example, biofouling on the hulls of ships results in a significant increase in drag and thus increased fuel consumption. It is estimated that up to 40% of the increase in fuel consumption can be attributed to biofouling. Since large oil tankers or container shipping ships can consume up to €200,000 worth of fuel per day, significant savings are possible with effective antifouling methods.

[0007] WO2014 / 188347 discloses methods and systems for preventing biofouling, wherein all surfaces or a significant amount of the surfaces (such as a ship hull) to be kept clean and free from fouling are covered with a layer that emits germicidal light (specifically UV light). Thus, it is known to use optical methods, specifically the use of ultraviolet light (UV). It is well known that with sufficient UV light, most microorganisms are killed, become inactive or unable to reproduce. This effect is mainly governed by the total dose of UV light. A typical dose to kill 90% of a certain microorganism is 10 mW-hours per square meter.

[0008] Ultraviolet (UV) is that part of electromagnetic light bounded by the short wavelength limit of the visible spectrum and the X-ray radiation band. The spectral range of UV light is by definition between 100 nm and 400 nm and is invisible to the human eye. Using the CIE classification, the UV spectrum is subdivided into three bands:

[0009] UVA (long wavelength) from 315 nm to 400 nm

[0010] UVB (medium wavelength) from 280 nm to 315 nm

[0011] UVC (short wavelength) from 100 nm to 280 nm

[0012] Various light sources for generating UV are known, such as low-pressure mercury discharge lamps, medium-pressure mercury discharge lamps, and dielectric barrier discharge lamps.

[0013] A preferred option as proposed in WO2014 / 188347 for example is a low-cost, lower-power UV LED. LEDs generally can be included in smaller packages and consume less power than other types of light sources. LEDs can be manufactured to emit (UV) light of various desired wavelengths, and their operating parameters (most significantly, the output power) can be controlled to a high degree. A suitable germicidal dose can be easily achieved using existing UV LEDs.

[0014] Most of the light-emitting panels are always below the water level. However, the water panels near the water level can emit light partially above the water level. This depends on the design of the ship. The intensity of UV-C light propagating through the adjacent (such as less than 2 m) air can then be above the safety limit for maximum exposure to humans.

[0015] WO2016 / 193114 discloses a solution to this problem, wherein the water switch is closed to enable the supply of current to the light source. The water switch uses the conductivity of water to form an electroconductive coupling between the switch terminals.

[0016] However, this approach means sacrificing the advantage of complete galvanic isolation of the lighting circuit from the boat and from the water. Galvanic contact with seawater will have the problem of water ingress, and due to gas formation by electrolysis, they are less safe for the electrical isolation and corrosion of the lighting panel.

[0017] There remains a need for improved ways of controlling light to prevent the activation of light sources not submerged in water. Summary of the Invention

[0018] The present invention is defined by the claims.

[0019] According to an example of an aspect of the present invention, there is provided an anti-fouling lighting panel for mounting on a surface to protect the surface from biofouling when the surface is submerged in water, comprising:

[0020] A light source arrangement;

[0021] A non-contact water sensor for sensing water to thereby detect whether the light source arrangement or a part of the light source arrangement is submerged in water; and

[0022] A controller for controlling the light source arrangement or the part of the light source arrangement according to the output of the water sensor.

[0023] The lighting panel thus includes a water sensor such that light generation can be controlled according to the presence or absence of water above the light source arrangement (or a part thereof). This saves power when the light source output is not needed and prevents light output through the air. Air results in lower attenuation of the light output, and it may be desirable to prevent the light output from reaching objects (such as people) that are close enough to the surface to be illuminated by the light output.

[0024] The term "non-contact" means that the sensor (especially the conductive part of the sensor) does not contact the water to be sensed. Sensing is thus based on a change in the permittivity, permeability, or optical properties near the sensor and without contacting the sensor. Thus, sensing can be non-contact remote sensing of water. Sensing does not utilize the conductivity of water, but instead relies on other properties that can be remotely interrogated using an electric field, magnetic field, or optical illumination. This avoids the need to protect the sensor components from salt water. Alternatively, the same protective material around the light source can be used to protect the water sensor.

[0025] Therefore, the protective outer coating (which will contact the water being sensed) should not be considered part of the sensor. The lighting panel thus includes a protective electrical insulating layer between the sensor and the water to be sensed. The electrical insulating layer can include one side of the encapsulation surrounding the lighting panel.

[0026] Preferably, the controller is adapted to switch off the light source arrangement or the part of the light source arrangement when the light source arrangement or the part of the light source arrangement is not immersed in water. Thus, no light output through air is provided. An alternative is to reduce the intensity, but not to switch off the light source arrangement (or part thereof) completely.

[0027] The light source arrangement may include a plurality of rows of light sources, each row including one of the parts of the light source arrangement, wherein a water sensor is provided for each row. The rows are for example intended to be horizontal in use, so that the water level around the hull of a ship will cause different rows of light sources to be immersed, depending on the load of the ship and the design of the ship. Thus, the light output can be controlled dynamically.

[0028] The water sensor may include a capacitive sensor, including a sensing plate, a ground electrode, and a capacitance readout circuit. The capacitance to be read out will be affected by the presence of water. Specifically, the ground electrode and the sensing plate are designed such that the presence or absence of water will cause a substantial and measurable difference in the dielectric constant between the ground electrode and the sensing plate.

[0029] The water sensor may alternatively include an inductive sensor, including an oscillator circuit, a sensor coil, a ground shield, and a frequency detector circuit, the ground shield having an opening that is exposed to water when the water sensor is immersed. The presence or absence of water near the opening then changes the magnetic coupling and thus the oscillation frequency.

[0030] The water sensor may alternatively include an optical sensor. For example, the amount of reflection of the generated light may depend on the presence or absence of water. For example, if the exposed surface is in contact with air, total internal reflection of the emitted light may irradiate the sensor, while if the exposed surface is in contact with water, the emitted light may propagate into the water.

[0031] The light emitting panel may further include an inductive power receiver, the inductive power receiver including one or more windings for alignment with one or more primary windings of an inductive power transmitter. Thus, power is provided to the light emitting panel by radio inductive energy transfer.

[0032] The present invention also provides an anti-siltation light emitting system, comprising:

[0033] An inductive power transmitter for mounting on the surface and including one or more primary windings; and

[0034] A light emitting panel as described above for mounting above the inductive power transmitter and including an inductive power receiver, the inductive power receiver including one or more windings for alignment with the one or more primary windings.

[0035] The system creates a transformer that provides galvanic isolation between the power source and the light-emitting panel.

[0036] The inductive power transmitter is, for example, for mounting against a surface, and the light-emitting panel is for mounting above the inductive power transmitter. The galvanically isolated light-emitting panel is thus the outer layer.

[0037] The inductive power transmitter may include an elongate power strip, and the light-emitting panel includes an edge region that overlaps the elongate power strip, where the inductive power receiver is present. Thus, one or more coils occupy a relatively small area of the light-emitting panel. A grid may be formed by the power strip (e.g., arranged vertically) and the light-emitting panel (e.g., arranged horizontally).

[0038] The inductive power transmitter includes, for example, a ferrite sheet under the primary winding and thus between the surface to be protected and the winding. System efficiency can thus be maintained high, for example, close to 50%. The ferrite sheet is between the surface (e.g., the hull of a ship) and the primary winding of the inductive transformer to prevent eddy currents through the conductive hull (or other conductive layer defining the surface to be protected).

[0039] The inductive power receiver includes, for example, a secondary winding formed on or in a printed circuit board. PCB material is typically an absorber of the generated UV light, so it should have a minimal possible area. It should also be thin to maintain flexibility.

[0040] The light-emitting panel has, for example, a thickness of less than 5 mm (e.g., less than 4 mm, e.g., less than 3 mm). This thickness typically includes the printed circuit board and the protective coating.

[0041] For example, the light-emitting panel includes a silicone coating. This coating can perform an optical function (e.g., light guiding) as well as a protective function. It can be selected to have a relatively high transparency to the generated UV light.

[0042] The inductive power transmitter includes, for example, a resonant circuit having a resonant frequency of 50 kHz to 1 MHz (e.g., 50 kHz to 200 kHz, e.g., 60 kHz to 90 kHz).

[0043] The light source arrangement includes, for example, an array of UV-C LEDs having wavelengths between 270 nm and 280 nm.

[0044] The system may include multiple inductive power transmitters and multiple light-emitting panels. One inductive power transmitter may be associated with one or more light-emitting panels.

[0045] The present invention also provides a method for protecting a surface from biological fouling by generating anti-fouling light through operating a light source arrangement when the surface is submerged in water, the method comprising:

[0046] sensing water by non-contact sensing so as to detect whether the light source arrangement or a part of the light source arrangement is submerged in water; and

[0047] controlling the light source arrangement or the part of the light source arrangement according to the water sensor output.

[0048] The method may comprise turning off the light source arrangement or the part of the light source arrangement when the light source arrangement or the part of the light source arrangement is not submerged in water.

[0049] The light source arrangement may comprise a plurality of rows of light sources, each row comprising one of the parts of the light source arrangement, wherein the method comprises sensing water near each row.

[0050] These and other aspects of the present invention will be apparent and will be elucidated with reference to the (one or more) embodiments described hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] For a better understanding of the present invention and to more clearly show how it may be implemented, reference will now be made, by way of example only, to the accompanying drawings, in which:

[0052] Figure 1 an anti-fouling lighting system applied to a ship to protect the surface of the ship in contact with water (i.e., the hull surface) is shown;

[0053] Figure 2 a cross-section (in a horizontal plane) of an inductive power transmitter and a lighting panel is shown;

[0054] Figure 3 the coil arrangement is shown in more detail;

[0055] Figure 4 an example of the structure of the lighting panel is shown;

[0056] Figure 5 the lighting panel is shown as viewed from the light-emitting surface;

[0057] Figure 6 a first example of a non-contact water sensor circuit based on capacitive sensing is shown;

[0058] Figure 7 components embedded in the lighting panel are shown Figure 6 are shown;

[0059] Figure 8Shows a second example of a non-contact water sensor circuit based on magnetic inductive sensing; and

[0060] Figure 9 Shows a third example of a non-contact water sensor circuit based on optical sensing. Detailed Description

[0061] The present invention will be described with reference to the accompanying drawings.

[0062] It should be understood that the detailed description and specific examples are intended for illustrative purposes only while indicating exemplary embodiments of the apparatus, system, and method, and are not intended to limit the scope of the present invention. These and other features, aspects, and advantages of the apparatus, system, and method of the present invention will be better understood from the following description, the appended claims, and the drawings. It should be understood that the drawings are merely schematic and not drawn to scale. It should also be understood that the same reference numerals are used throughout the drawings to represent the same or similar components.

[0063] The present invention provides an anti-fouling luminescent system for an anti-fouling luminescent panel that is used to protect a surface from biofouling when the surface is submerged in water. A non-contact water sensor is used to sense water to detect whether the light source arrangement or a part of the light source arrangement is submerged in water. The light source arrangement or the part of the light source arrangement is controlled according to the output of the water sensor.

[0064] Figure 1 Shows an anti-fouling luminescent system applied to a ship 1 to protect the surface of the ship in contact with water (i.e., the hull surface), and the anti-fouling luminescent system can be adjusted according to the present invention.

[0065] The anti-fouling system includes a set of inductive power transmitters 10 mounted on the surface. They take the form of power feed lines extending vertically against the hull. At the upper end, the feed lines are connected to a source of electrical power (not shown). Each of the inductive power transmitters includes a set of one or more primary windings. In this document, a set of primary windings (whether there is one or more than one winding) is referred to as a primary coil.

[0066] A set of luminescent panels 20 is also mounted on the surface. Each of the luminescent panels includes a light source arrangement and an inductive power receiver having a set of one or more secondary windings aligned with the set of primary windings. In this document, a set of secondary windings (whether there is one or more than one winding) is referred to as a secondary coil. Thus, the term "coil" generally refers to a set of windings forming one side of a transformer.

[0067] As will be apparent from the following description, there may be multiple coils on each power feed line, such as one or more coils on the power feed line at the position of each luminescent panel.

[0068] Figure 2 Shows a cross-section (in a horizontal plane) through a power feed line (inductive power transmitter 10) and through a light-emitting panel 20. The inductive power transmitter includes a primary coil 12 and a ferrite sheet 14 between the windings of the primary coil and the metal of the ship's hull 16. The surface 18 of the hull is the surface to be protected from fouling. The ferrite sheet prevents eddy currents in the metal of the ship's hull 16, thereby increasing the efficiency of energy transfer.

[0069] In the example shown, the light-emitting panel substantially completely covers the surface 18. Thus, the surface 18 is protected by the light-emitting panel, and it is the exposed surface of the light-emitting panel that is vulnerable to fouling. Thus, the light emission provided by the light-emitting panel is intended to prevent the formation of fouling organisms on the surface of the light-emitting panel.

[0070] However, this is still to be understood as forming a system for protecting the hull surface from biofouling (since in the absence of the light-emitting system, the hull surface would be subject to biofouling).

[0071] Alternative arrangements could for example have a light-emitting panel that only covers a small part of the surface to be protected, and the light is directed or guided towards the surface to be protected. In such a case, the major part of the hull surface is actually exposed to water and is thus vulnerable to biofouling.

[0072] In Figure 2 the example shown, the inductive power transmitter 10 is mounted against the hull surface 18, and the light-emitting panel 20 is mounted on top of the inductive power transmitter.

[0073] Specifically, the edge region 22 of each light-emitting panel 20 overlaps the feed line. Each of the light-emitting panels 20 has a secondary coil 24 and a light source arrangement 26 located in that edge region.

[0074] The secondary winding is aligned with the primary winding to provide inductive power transfer. The wirelessly transmitted power is used by the light-emitting panel 20 to power the light source arrangement 26.

[0075] The primary coil can be formed on or within a printed circuit board of the feed line, and the secondary coil can also be formed on or within a printed circuit board of the light-emitting panel. The light source arrangement can also be formed on a printed circuit board that can be separate from or the same as the printed circuit board of the secondary coil. A common flexible printed circuit board can for example allow the light-emitting panel to conform to the profile of the underlying feed line. Alternatively, there can be separate printed circuit boards in the light-emitting panel and electrical connections between them.

[0076] Alternatively, the light source arrangement can be formed as a line grid structure. This reduces the PCB area as only the PCB for the secondary coil is required.

[0077] The printed circuit board is not shown in the figures to keep the structure shown simple.

[0078] For example, a 100 kHz to 150 kHz sine wave can be supplied to the primary coil of the inductive power transmitter 10 during operation of the light emission system. To compensate for the capacitive leakage current to the hull 16 at the location of the feeder line, a capacitor can be further provided for the feeder line to achieve low-pass filtering. This is advantageous, for example, if a high-efficiency switching amplifier is used to generate the AC supply. In such a case, the low-pass filtering is for the residual higher frequency harmonics of the amplifier.

[0079] An alternative is to use a resonant circuit to generate the AC supply. For example, each feeder line can include a resonant circuit, based on a capacitive resonant circuit, having a resonance in the range of 60 kHz to 90 kHz.

[0080] Generally, the operating (resonant or slave) frequency can be in the range of 50 kHz to 1 MHz (e.g., 50 kHz to 200 kHz, e.g., 60 kHz to 90 kHz).

[0081] Figure 3 A coil arrangement is shown.

[0082] Figure 2 The example of... has a light-emitting panel that overlaps with the associated feeder line at one edge. In Figure 3 ..., the light-emitting panel 20 overlaps with the feeder lines 10 at two lateral edges, and each feeder line 10 has a pair of primary coils arranged along its length. One coil in the pair supplies power to the light-emitting panel on one side, and the other coil in the pair is for supplying power to the light-emitting panel on the other side. In this way, each light-emitting panel is supplied with power from both sides.

[0083] All the coils of the feeder line can have the same phase, which contributes to the electrical redundancy of the light emission system 40. If the feeder line is damaged, the light source arrangement 26 can still operate fully. In this regard, the feeder line can be designed to deliver electrical power at an increased level twice that of the normal level.

[0084] Thus, there can be one coil assembly (i.e., primary coil and secondary coil) for each light-emitting panel ( Figure 2 ) or two coil assemblies for each light-emitting panel ( Figure 3 ).

[0085] There can be, for example, between 2 and 50 light-emitting panels per feeder line, such as 20 rows of individual tiles connected to the feeder line.

[0086] In the example shown, the feeder line extends in a substantially vertical direction along the side of the ship. However, any suitable arrangement of the feeder line is possible. The feeder line can, for example, cover the weld seams and / or other surface irregularities of the ship's hull.

[0087] Figure 4 An example of the structure of a light-emitting panel 20 having a plurality of light sources 40 is shown, in which the plurality of light sources 40 are side-emitting UV-C LEDs, where light is emitted mainly from the sides of the LEDs and substantially parallel to the surface. The light sources 40 are encapsulated in a liquid-tight optical medium 42 to guide at least a portion of the light 44 emitted from the light sources 40 via total internal reflection through the optical medium.

[0088] An optical structure 46 is provided to interfere with total internal reflection and scatter the light, and then direct the scattered light 48 out of the optical medium 42 towards the target of the light, which is the area where biofouling organisms are present.

[0089] The biofouling organisms on the surface 52 will directly receive the scattered light 48 before the scattered light 48 enters the water.

[0090] In addition, some of the internally scattered light 48 that does not enter the water will encounter external scattering sites. This creates illumination 50 in the water, and some of the illumination 50 will also be reflected back from the surface 52 of the light-emitting panel 20 where biofouling is to be prevented.

[0091] Irradiation means that the single-celled biological mechanism at the surface 52 will stop growing and dividing and will thus die under the influence of the UV-C light.

[0092] The optical medium is relatively thin such that the light-emitting panel can be considered a two-dimensional structure. The optical structure 46 for scattering the light can be dispersed in one or more portions of the optical medium material, possibly throughout all of it, and the light output can be approximately uniform or otherwise localized.

[0093] Internal scattering centers having different structural properties can be combined to provide optical as well as structural properties such as abrasion and / or impact resistance. Suitable scatterers include opaque objects, but largely translucent objects such as small air bubbles, glass, and / or silica can also be used; the only requirement is that the change in refractive index occurs for the wavelength(s) used.

[0094] The principle of light guiding and diffusing light on a surface is well known and is widely applied in various fields. Here, for the purpose of anti-fouling, this principle is applied to UV light.

[0095] To maintain the conditions for total internal reflection, the refractive index of the light guide material should be higher than that of the surrounding medium. However, the use of a (partial) reflective coating on the light guide and / or the use of the reflective properties of the protected surface itself (such as the hull of a ship) can also be used to establish the conditions for guiding light through the optical medium.

[0096] In the above example, the light-emitting panel forms a new surface on the surface to be protected and guides light outward from the surface to be protected. However, an alternative is that the light-emitting panel is spaced above the surface to be protected and guides the light back toward the surface to be protected.

[0097] A small air gap can be introduced between the light source arrangement of the light-emitting panel and the surface to be protected. UV light can travel better in air than in the optical medium, with less absorption, even when the optical medium is designed as a light guide material.

[0098] Since most materials have a (very) limited transmittance for UV light, attention must be paid in the design of the optical medium. Therefore, a relatively small pitch of low-power LEDs can be selected to minimize the distance that the light has to travel through the optical medium.

[0099] In one example, the optical medium 42 includes silicone resin and is designed to have good UV-C transparency.

[0100] A fixed encapsulation can be used, as Figure 4 shown. However, a hollow structure can alternatively be used, such as a silicone resin pad with spacers that keep it spaced a small distance from the protected surface. This creates air channels through which the UV light can propagate with higher efficiency. The use of the air-filled channels provided by such structures allows the UV light to be distributed over a significant distance in the optical medium of a material that would otherwise absorb the UV light too strongly to help prevent fouling. Similarly, individual bagged parts can be formed.

[0101] Figure 5 The light-emitting panel 20 is shown as viewed from the front. The light-emitting panel includes a two-dimensional array of LEDs 40 and a primary coil 24 at the edge region 22.

[0102] The LEDs 40 are arranged in multiple rows. According to the present invention, each row of LEDs in the panel or more preferably within the panel has a water sensor 60. The LEDs 40 are provided on a printed circuit board, and the printed circuit board traces also define the windings of the secondary coil 24. The water sensor can be provided on the PCB, using the mounted components and / or the components formed by the PCB traces.

[0103] The output of the water sensor is used to control the light source arrangement, specifically the associated row of the light sources of the light source arrangement, depending on the water sensor output.

[0104] The water sensor output can directly control an interrupt switch, for example, in which case the switch serves as a controller. Alternatively, there can be a separate controller to which the sensor output is provided, such as an IC. The controller IC then provides a control signal to the isolation switch, or it can provide an analog control of the light output.

[0105] In the simplest implementation, a simple MOSFET circuit is used as the switch, and the output of the water sensor controls the gate of the MOSFET circuit. The MOSFET circuit can then be considered a controller.

[0106] The controller (whether it is a switch or a controller IC) is preferably adapted to turn off the light source arrangement or a part of the light source arrangement when not immersed in water. However, an alternative is to reduce the light output intensity, for example, by increasing the series impedance in series with the light source 40 in the row.

[0107] The water sensor does not rely on physical contact with water and thus does not utilize the conductivity of water. Instead, it is a non-contact sensor that relies on an electric field, a magnetic field, or a change in optical properties depending on the presence or absence of water in the vicinity of the sensor.

[0108] A first example of a possible water sensor is a capacitive sensor. In Figure 6 An example including a sensing 70 and a ground electrode 72 and a capacitance readout circuit 74 is shown. Such readout circuits are well known, for example, for touchpad sensing.

[0109] The input voltage is regulated by a voltage regulator 76 and is delivered to a reference capacitor C1. The voltage across the capacitance Cs to be sensed is provided to the sensing terminal of the readout circuit 74.

[0110] The sensing plate does not have to be in contact with water. Instead, as long as the presence or absence of water affects the capacitance between the sensing plate 70 and the ground electrode 72, the presence of water can be detected.

[0111] Figure 7 The arrangement of components in the light-emitting panel is shown. The sensing plate 70 is buried in the optical material of the panel, but the presence of water at the surface affects the dielectric coupling between the sensing plate 70 and the ground electrode 72.

[0112] A second example of a possible water sensor is an inductive sensor. In Figure 8Examples are shown. The sensor includes an oscillator circuit 80 and a sensor coil 82. The sensor coil is covered by a conductive ground shield 83 (forming a Faraday shield) having an opening 84. When the water sensor is immersed, the opening 84 is exposed to water. However, the sensor loop is not exposed for direct contact with water. There is an insulating protective layer, i.e., an optical material in which the light-emitting panel is encapsulated, between the coil and the water. Thus, direct contact between water and the conductive parts of the sensor, such as the sensor coil, is avoided. The sensor loop functions as a loop antenna. The oscillator operates, for example, between 50 MHz and 500 MHz. A change in the permeability near the gap causes a shift in frequency, which is detected by a frequency detector circuit 86.

[0113] The sensor function can be incorporated into an integrated circuit, or it can be formed using traces of a PCB.

[0114] Further details of such a sensing method in different technical fields can be found in WO2018 / 202486. The frequency shift is the result of a magnetic field induced by eddy currents. These eddy currents depend on the permeability (i.e., magnetic impedance) of the material near the opening 84. Thus, the sensor can be considered a magnetic impedance sensor.

[0115] A third example of a water sensor may be an optical sensor. In Figure 9 Examples are shown.

[0116] The sensor includes a sensor light source 40 and an optical detector 90. The light source 40 can be one of the UV-C light sources, or it can be a dedicated light source specifically selected for the optical sensing function.

[0117] The optical detector 90 is for light reflected from water or air or from a refractive index boundary to water or air. A part of the light detector is covered.

[0118] For example, light emitted at a specific angle can propagate into the water, or when air is present, it can be reflected by the refractive index boundary. Thus, the detection of total internal reflection can be used to detect the presence of an air interface, and thereby detect when the light-emitting panel is not immersed. If a thin layer of water is present on the sensor (even if the sensor is not immersed), total internal reflection can still be detected from the outermost water-air interface. Thus, the sensor does not have to be completely dry to detect air.

[0119] The direction filter 92 can ensure that only light in the desired sensing direction is detected. Similarly, a color filter can be used to filter light of a specific wavelength to correspond to the dedicated light source 40 of the optical sensor.

[0120] The optical sensor can alternatively detect backscattering (instead of reflection from the refractive index boundary). The backscattering from water will produce a higher light intensity than the backscattering from air.

[0121] Therefore, different optical sensing methods are possible.

[0122] Therefore, it can be seen that there are three main non-contact methods for determining the water level near the ship and thus turning off the light source. These are based on capacitive sensing, inductive sensing, and optical sensing (which can use UV-C light or other light dedicated to optical sensing).

[0123] The typical secondary side current is 0.1 A, and the typical desired secondary side voltage is about 40 V. For safety, a maximum voltage of 50 V rms can be considered (by way of example only). The system is designed to operate below the maximum voltage considering all the characteristics of inductive coupling and the spread of the current or below the maximum voltage considering all the characteristics of inductive coupling and the spread of the current. For a given operating voltage, the required current depends on the required power. Higher voltages achieve lower currents and vice versa.

[0124] The feeder line uses, for example, a PCB with a thickness of less than 1 mm (e.g., 0.5 mm), resulting in a molded structure thickness of approximately 3 mm.

[0125] The light-emitting panel has, for example, a PCB thickness of 0.8 mm and a total thickness of silicone resin below 5 mm (e.g., in the range of 2 mm to 4 mm).

[0126] The present invention is particularly advantageous for maritime objects, but is not limited to objects used in seawater and in any type of water known to contain biofouling organisms. Examples of maritime objects include ships and other vessels, offshore bases, ocean-based oil or gas facilities, buoyancy devices, support structures for wind turbines in the sea, structures for harvesting wave / tidal energy, subsea valve boxes, underwater tools, etc.

[0127] In a preferred example, the light source is a UV LED as explained above. The grid of UV LEDs can be encapsulated in a liquid-tight enclosure, and silicone resin is just one example. The UV LEDs can be electrically connected in a series and / or parallel arrangement. The UV LEDs are, for example, encapsulated surface-mounted LEDs, in which case they may already include optical elements to emit light from the LED package at a wide emission angle. In other embodiments, the UV LEDs can be LED die, which generally do not include optical elements but are significantly thinner than encapsulated LEDs. By way of example, the LED die can be picked and placed onto the surface of an optical medium.

[0128] Silicone materials can be selected to provide optical transmission for UV light with minimal loss compared to other materials. This is especially the case for shorter wavelength light (e.g., UV light with a wavelength below 300 nm). A particularly effective group of silicone materials is or at least contains the so-called methyl silicone according to the general chemical formula CH3[Si(CH3)2O] n Si(CH3)3, where "n" indicates any suitable integer.

[0129] Silicone materials are also flexible and elastic, making them robust, durable and able to withstand compression such as that caused by impacts, collisions, etc. of objects against a surface (e.g., a ship hitting a dock). In addition, deformation due to temperature fluctuations, pounding by waves, bending of the ship with expansion, etc. can be accommodated.

[0130] At least part of the light emitted by one or more light sources can be diffused in a direction having a component substantially parallel to the surface to be protected. This promotes the distribution of light over a large distance along the protected surface or the application surface of the foil, which helps to obtain a suitable intensity distribution of anti-sedimentation light.

[0131] The wavelength conversion material can be included in the optical medium, and at least part of the anti-sedimentation light can be generated by optically exciting the wavelength conversion material with light having a first wavelength that causes the wavelength conversion material to emit anti-sedimentation light at another wavelength. The wavelength conversion material can be provided as an upconversion phosphor, quantum dots, a nonlinear medium such as one or more photonic crystal fibers, etc. Since absorption and / or scattering losses in the optical medium for light having a wavelength different from and mostly longer than UV light tend to be less pronounced in the optical medium, non-UV light can be generated more energy-efficiently and transmitted through the optical medium and UV anti-sedimentation light (i.e., emission from the surface into the liquid environment) can be generated at or near its desired use location.

[0132] The strategies described above utilize side-emitting LEDs and optical scattering sites. However, a light diffusion arrangement can be used to generate sideway light. For example, a cone can be arranged in the optical medium and positioned opposite the light source, where the opposing object has a surface area perpendicular to the protected surface at a 45° angle in order to reflect the light emitted by the light source perpendicular to the surface in a direction substantially parallel to the surface.

[0133] The LED can be DC-driven. However, a pair of back-to-back parallel LEDs can be driven by an AC drive signal.

[0134] As mentioned above, the LEDs are preferably mounted on a PCB, and PCB traces (on the PCB surface or within the layers of the PCB) form the receiver coil. However, the LED grid can alternatively be formed by connecting the LEDs to connection nodes of a stand-alone wire structure by means of soldering, bonding or any other known electrical connection technique. This can be combined with a secondary coil on a smaller PCB.

[0135] The present invention can be applied to a wide variety of fields. Almost any object in contact with natural water will suffer from biofouling over time. This can impede, for example, the water intake of a desalination plant, clog the pipes of a pumping station, or even cover the walls and bottom of an outdoor swimming pool. All of these applications will benefit from the currently provided methods, lighting modules, and / or systems, namely an effective thin additional surface layer that prevents biofouling over the entire surface area.

[0136] Although UV light is the preferred solution, other wavelengths are also contemplated. Non-UV light (visible light) is also effective in preventing biofouling. Typical microorganisms are less sensitive to non-UV light than to UV light, but can generate a much higher dose in the visible spectrum per unit input power to the light source.

[0137] UV LEDs are ideal sources for thin light-emitting surfaces. However, UV sources other than LEDs can also be used, such as low-pressure mercury vapor lamps. The form factors of these light sources are quite different; mainly, the sources are much larger. This results in different optical designs to distribute all the light from a single source over a large area. Further, a significant contribution of light in the desired wavelength and / or wavelength combination can be generated. Instead of using a thin layer that emits UV light outwardly away from the protected surface to avoid biofouling, biofouling can also potentially be removed by applying UV light from the outside in the direction of the protected surface, as explained above. The light-emitting panel can alternatively emit anti-fouling light in directions towards and away from the surface to be protected.

[0138] In the above example, the light-emitting panel overlaps the feeder line. This provides galvanic isolation between the power source and the structure exposed to water. The light-emitting panel also protects the feeder line. Alternatively, the feeder line can be provided on top of the light-emitting panel. Separate electrical isolation can be provided (e.g., at the top of the feeder line). The surface of the feeder line will then be vulnerable to biofouling, so it should then be ensured that light reaches the surface of the feeder line, either by transmission through the feeder line or by reflection or waveguide transmission within the light-emitting panel. Thus, both the inductive power transmitter and the light-emitting panel are used for mounting on a surface, but in either order.

[0139] The light-emitting panel, for example, has a length (along the horizontal row direction) in the range of 1 m to 5 m and a height (along the vertical column direction) in the range of 50 cm to 150 cm. For example, a small panel size can be 600 mm x 1200 mm, and a large panel size can be 1 m x 4 m. An exemplary area to be covered (such as one side of a ship hull) can be approximately 100 m long by 10 m high.

[0140] Those skilled in the art can understand and achieve variations of the disclosed embodiments when practicing the claimed invention by studying the drawings, the disclosure, and the claims. In the claims, the word "comprising" does not exclude other elements or steps, and the words "a" or "an" do not exclude a plurality. Although specific measures are recited in mutually different dependent claims, this does not indicate that a combination of these measures cannot be used advantageously. If the term "adapted to" is used in the claims or the specification, it should be noted that the term "adapted to" is intended to be equivalent to the term "configured to". Any reference signs in the claims should not be construed as limiting the scope.

Claims

1. An anti-fouling luminescent panel for installation on a surface to protect the surface (16) from biofouling when the surface is submerged in water, comprising: A light source arrangement (26) including a plurality of sections; A non-contact water sensor (60) for sensing water to detect whether each section of the light source arrangement is submerged in water, wherein the light source arrangement includes a plurality of rows of light sources, and wherein each row of the light sources has a non-contact water sensor; and A controller for separately controlling the associated rows of the light sources according to the output of the non-contact water sensors associated with the rows of the light sources, Wherein the water sensor includes: A capacitive sensor including a sensing plate, a ground electrode, and a capacitance readout circuit, or An inductive sensor including an oscillator circuit, a sensor coil, a ground shield, and a frequency detector circuit, the ground shield having an opening exposed to water when the water sensor is submerged.

2. The light-emitting panel according to claim 1, wherein, The controller is adapted to turn off the rows of the light sources when the rows of the light sources are not submerged in water.

3. The luminescent panel according to any one of claims 1 to 2, further comprising: An inductive power receiver (24) including one or more windings for alignment with one or more primary windings of an inductive power transmitter.

4. An anti-fouling luminescent system including the luminescent panel according to any one of claims 1 to 2, the anti-fouling luminescent system further comprising: An inductive power transmitter (10) for installation on the surface (16) and including one or more primary windings, Wherein the luminescent panel is mounted above the inductive power transmitter and includes an inductive power receiver (24), the inductive power receiver including one or more windings for alignment with the one or more primary windings.

5. The anti-siltation lighting system according to claim 4, wherein, The inductive power transmitter (10) includes an elongated power strip, and the luminescent panel includes an edge region (22) overlapping the elongated power strip (10), and the inductive power receiver (24) is formed in the edge region (22).

6. The anti-siltation lighting system according to claim 4 or 5, wherein, The inductive power transmitter includes a ferrite sheet (14) under the windings.

7. The anti-siltation lighting system according to claim 4 or 5, wherein The luminescent panel includes a silicone coating and a printed circuit board for at least the one or more secondary windings.

8. The anti-fouling luminescent system according to claim 4 or 5, including a plurality of inductive power transmitters (10) and a plurality of luminescent panels (20).

9. A method of protecting a surface from biofouling by generating anti-fouling light by operating a light source arrangement when the surface (16) is submerged in water, the method comprising: Sensing water by a non-contact water sensor to detect whether sections of the light source arrangement are submerged in water, wherein the light source arrangement includes a plurality of rows of light sources, and wherein each row of the light sources has a non-contact water sensor; and Separately controlling the associated rows of the light sources according to the output of the non-contact water sensors associated with the rows of the light sources, Wherein sensing water by a non-contact water sensor includes using: A capacitive sensor, which includes a sensing plate, a ground electrode, and a capacitance readout circuit, or An inductive sensor, which includes an oscillator circuit, a sensor coil, a ground shield, and a frequency detector circuit, and the ground shield has an opening that is exposed to water when the water sensor is immersed.

10. The method according to claim 9, including turning off the row of the light source when the row of the light source is not immersed in water.

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