System comprising a decoating apparatus and associated methods and use

Abstract

The present invention discloses a system designed to decoat a portion of a coating system present on a surface of a window The system comprises a decoating apparatus designed to decoat a decoatable area of the coating system; the decoating apparatus comprises a laser device and a displacement means; the laser device comprising an optical laser unit to generate a laser beam designed to decoat a laser zone; the displacement means designed to displace the laser device along the decoatable area. The system further comprises a protection means designed to be opaque to the wavelength of the laser beam and designed to reduce the decoatable area to an effective area. The protection means comprises an attachment means designed to attach the protection means between the laser device and the window. The present invention also relates to decoating methods and use.

Description

System comprising a decoating apparatus and associated methods and useDescriptionTechnical Field

[0001] The present intention relates to a system comprising a decoating apparatus. The system is designed to decoat a portion of a coating system present on a surface of a window.

[0002] The present invention relates to a decoating method to at least partially decoat a portion of a coating system present on a surface of a window mounted on a stationary object, for instance a building, or mounted on a mobile object, for instance a vehicle, a rapid transit system such as a train, tram or alike.

[0003] Thus, the invention concerns multiple domains where windows need to be at least partially decoated, meaning removing part of said coating system, to improve the electromagnetic transparency.Background Art

[0004] A standard single-layered window has poor thermal performances. This is why most windows are now built using two or more glass panels separated by a gas and / or polymer-based interlayer. This kind of windows are is called a multiglazed window.

[0005] A glass panel is low in reflectance for RF radiation. Low in reflectance for RF radiation means that RF radiation are mostly transmitted through the material where high in reflectance for RF radiation means that RF radiation are mostly reflected on the surface of the material and / or absorbed by the material and the attenuation is at level of 20 decibels (dB) or more. Low in reflectance means an attenuation at level of 10 decibels (dB) or less.

[0006] A coating system is typically applied on the interface of one or several glass panels of a multi-glazed window in order to further improve the multiglazed window properties.

[0007] This coating system can either improve the multi-glazed window insulation, reduce the amount of infrared and / or ultraviolet radiation entering the multi-glazed window and / or keep the sun’s heat out of a space wherein such multi-glazed window insulation is used.

[0008] However, this type of coating systems is generally metal-based and therefore acts as a Faraday cage, preventing electromagnetic waves such as radio waves, from entering or leaving the space and then is high in reflectance for RF radiation. The coating system is high in reflectance meaning that the coating system is low in transmittance for RF radiation. Low in transmittance means a transmission with an attenuation at level of 20 decibels (dB) or more. It is understood that the dielectric substrate is low in reflectance, meaning an attenuation at level of 10 decibels (dB) or less.

[0009] Thus, these coatings can also affect the electromagnetic (EM) transparency of the window, which is important for the transmission of signals for wireless communication technologies like 4G, 5G, DSRC and Wi-Fi. To improve the EM transparency of a window, it may be necessary to remove or modify the existing coating system.

[0010] A decoating apparatus is a device that is designed for this purpose. It typically uses some form of chemical or mechanical treatment to remove a portion of the coating system from the window surface.

[0011] u sually, when a window is mounted in situ meaning that the window is mounted on a stationary object, for instance a building, or mounted on a mobile object, for instance a vehicle, a rapid transit system such as a train, tram or alike to close an opening in the stationary or the mobile object, windows are removed from the opening to treat their surfaces.

[0012] A treatment can be a laser scribing or like, or preferably a decoating of a coating system.

[0013] In order to improve the transmittance of a multi-glazed window containing a coating system, one can use a laser decoating system to remove at least one portion of the coating system. The total surface to be decoated is typically between 1 and 3% of the total coating system surface, in order to both improve the transmission of radio waves through the multi-glazed-window without impairing the properties of said coating system.

[0014] Preferably, to improve the transmission of a radio wave through the window, the decoating system will remove segments from the coating system and the sum of the longest sub-segment of each segment is equal to n / 2 wherein n is a positive integer greater than zero and lambda ( A ) is the wavelength of the radio wave. It is necessary to have a wide band frequencyselective surface in order to ensure the transmission of waves of different frequencies through the multi-glazed window, typically between 2GHz and lOOGhz. For instance, the decoating system can be configured to remove a segment of a length greater than 400 mm and a width between 10 and 100 pm.

[0015] Preferably, for some applications such as Wi-Fi, toll communication systems, 4G and / or 5G receptors and transmitters, a small decoating portion is desired instead of a large decoating portion. For instance, a small decoating portion has typically a length less than 400 mm.

[0016] A simple approach to solve this problem of RF energy reflection is to remove a portion of the coating system. This approach, however, reduces the solar control benefits offered by the multi-glazed window. Moreover, for multiglazed window located inside the building, the vehicle or the car, the decoated region would be unacceptably large. On top of that, the transition between the decoated portion and the coating itself is eye-visible and usually non-accepted by users.

[0017] Another solution has been to cut lines in the coating system to create a surface which is frequency selective: it has relatively high reflectivity / absorbance for solar energy but relatively low reflectivity / absorbance in the RF region of the electromagnetic spectrum. The cutting may be performed by laser ablation and the spacing of the slits is chosen to provide selectivity at the desired frequency.

[0018] To improve the transmittance of said multi-glazed window, WO 2015 / 050762 describes an apparatus comprising a laser light source and a lens array configured to focus said laser light source on a coating system of a multi-glazed window. Said apparatus is mounted on suction pads to secure said apparatus on said multi-glazed window. Said apparatus also comprises at least two motors configured to move said laser along rails along the X and Y axis. Said laser is capable of scribing a grid shape on said coating system to improve the electromagnetic transmission of said multi-glazed window.

[0019] However, said laser is always focused on a single point and cannot be adapted. In fact, this apparatus is only built to have a focal point in a specific surface and thus such apparatus are built for a single type of double-glazed window being two glass panels separated by a spacer creating a space filled with gas, where the coating system is positioned on the internal interface of thewindow. Hence, it is not possible to use this apparatus to other types of windows where the glass thickness is different or where the coating system is applied on a different interface. Such system needs to move the whole laser device to create an frequency selective surface. The programming of movement of the whole laser device thanks to motors permits to create a defined decoated area.

[0020] In another domain, US6,559,411 describes an apparatus for laser scribing a tin oxide layer coated on a glass panel substrate. A predetermined scribing is formed on the tin oxide layer by focusing a laser on said tin oxide layer and by displacing said glass panel substrate by a conveyor along the X or Y axis.

[0021] The programming of movement of the conveyor permits to create a defined decoated area.

[0022] Each time a new area with specific features has to be decoated, apparatus of the prior are must be reprogrammed to create the desired decoated area.

[0023] Moreover, systems described in prior art are heavy to mount on a multiglazed window due to displacement elements (rails, •••) and motors. The precision and the quality are hence not appropriate for small decoating portions due to movements of the apparatus. The decoating time is also long due to displacements of the laser light source especially for small decoating portion where many small displacements are needed within a short distance.

[0024] Thus, this apparatus can only be used in factories on glass panel that have just been manufactured. Hence, this apparatus cannot be used on a multi-glazed window of unknown structure, such as the number of glass panels, the number of lamination layers, the numbers of spacers, the number, nature and position of the coating system, ••• and that is already mounted on an object, for instance a building or a vehicle.

[0025] In addition, a large number of windows are already installed and are known to prevent the transmission of electromagnetic wave. Such windows cannot be replaced or be removed without important costs . The multi-glazed windows cannot be retrieved from the object, sent back to a factory to remove the part of the coating and then, sent back to be assembled again on the object. Such situations require the decoating process to be carried out in situ, when the multi-glazed window is mounted on the object. In most cases, the structure of these multi-glazed windows and the exact position of their coating system iscompletely unknown. It is therefore impossible for such apparatus to focus the laser properly on the coating system.

[0026] On top of that, when apparatus of the prior art are mounted on a multiglazed window, the tolerances of manufacture, the variability of mounting system occurs a variability of the distance between the coated surface and the decoating apparatus. Such variability implies that the focal point of the laser beam is not focused on the coated surface. The decoating of such apparatus of the prior art is not efficient, the laser beam being not focused at the right position.

[0027] Additionally, apparatus of the prior art cannot be aligned perpendicularly to the coating system to be treated causing a problem with the quality of the decoating. In fact, apparatus of the prior art are fixed to the window (or around) via suction pads, thus the parallelism in not possible with tolerances of the pads and the whole apparatus on top of the possible misalignment of the window or the curvature of said window. Then, misalignment needs to be calculated for each window once the apparatus is installed taking time, handling issues, •••

[0028] Based on that, apparatus of the prior art needs for each window to be reconfigured to define and decoat correctly inside a portion of said coating system. For each window, a positioning setting must be performed. This takes time and requires operators with a good knowledge of coating systems and computing skills. For example, apparatus of the prior art need to be attached to the window (or around) then a first step is to correctly position the structure around each window each time while ensuring the parallelism between the apparatus and the window that can only be a flatten window.

[0029] Hence, an ongoing technical issue is to obtain a decoating apparatus and process that can be used on multiple kind of multi-glazed windows and with different desire surface to decoat, wherein the position and the thickness of the glass panels and the position of the at least one coating system are not known; and that are able to work when said multi-glazed window is already mounted on an object while accessibility is limited by limiting operators handlings.Summary of invention

[0030] The present invention relates, in a first aspect, to a system. Said system comprises a decoating apparatus. The system is to decoat a portion of a coatingsystem present on a surface of a window. The system comprises a decoating apparatus designed to decoat a decoatable area of the coating system. The decoating apparatus comprises a laser device and a displacement means. The laser device comprising an optical laser unit to generate a laser beam designed to decoat a laser zone. The displacement means designed to displace the laser device along the decoatable area.

[0031] Preferably, the frequency of the laser beam equals to or is higher than substantially 20kHz.

[0032] The solution as defined in the first aspect of the present invention is based on the system further comprises a protection means designed to be opaque to the wavelength of the laser beam and designed to reduce the decoatable area to an effective area.

[0033] The term “opaque” in the sense of the present invention for the protection means that concentrated and powerful rays of the laser beam are blocked by the protection means and are not transmitted through the protection means. Such rays can be absorbed, diffused, and / or diffracted by the protection means.

[0034] The solution as defined in the first aspect of the present invention is also based on the protection means comprises a attachment means designed to attach the protection means between the laser device and the window.

[0035] The present invention also relates, in a second aspect, to a decoating method to at least partially decoat a portion of a coating system present on a surface of a window with a system according to the first aspect of the present invention. The decoating method comprises following steps: a) Positioning the protection means at the desired location to reduce the decoatable area to the effective area, b) Decoating a frequency selective surface on the decoatable area with the decoating apparatus.

[0036] Preferably, the decoating method is performed in situ meaning that the window is already mounted on a stationary object, for instance a building, or mounted on a mobile object, for instance a vehicle, a rapid transit system such as a train, tram or alike before performing the decoating method. That means that the window is already installed at its use position and the decoating method is performed on a window that is in use.

[0037] The present invention also relates, in a third aspect, to a multi portions decoating method at least partially decoat to decoat at least an effective area on a first window and an effective area on a second window; each of the windows are mounted on a stationary object, for instance a building, or mounted on a mobile object, for instance a vehicle, a rapid transit system such as a train, tram or alike, with a system according to the first aspect of the present invention. The multi portions method comprises following steps :1. Decoating a frequency selective surface on the first window with the decoating method according to the second aspect with a first protection means,2. Decoating a frequency selective surface on the second window with the decoating method according to the second aspect with a second protection means.

[0038] The present invention also relates, in a fourth aspect, to a protection means comprised in a system according to the first aspect to reduce a decoatable area to an effective area to avoid decoating a non-decoatable zone.

[0039] The present invention permits in these different aspects to decoat a large scope of type of windows such as curved, strong geometric and dimensional disparities between windows in a same row, strong geometric and dimensional disparities of surfaces while be able to decoat in situ, where the object comprising said window to treat is positioned. In case of a mobile object, the present invention permits also to decoat at any location without moving the mobile object in a specific shed to treat windows to reduce cost, immobilisation time, handling, logistics, •••

[0040] The present invention further permits to easily decoat windows even if windows not directly accessible meaning that even if the access to the window itself is very limited due to the presence of elements blocking access or preventing access to the surface itself, the present invention allows to decoat such windows. In fact, the decoating apparatus is able to decoat without being fixed or attached to the window or round the window.

[0041] The present invention further permits to decoat windows in situ without the need to remove window from the object to decoat in a factory reducing the handling, the risk of breakage, the logistics, •••

[0042] The present invention further permits to increase the flexibility of uses especially in terms of types of windows to treat and to decoat a large variety of shapes in a fast manner. The need to adapt for each shape software that are driven the movement of the laser device and / or the laser beam is limited.

[0043] It is noted that the invention relates to all possible combinations of features recited in the claims or in the described embodiments.

[0044] The following description relates to rapid transit system applications, but it’s understood that the invention may be applicable to others fields like automotive or building applications.Brief description of the drawings

[0045] This and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing various exemplifying embodiments of the invention which are provided by way of illustration and not of limitation. The drawings are a schematic representation and not true to scale. The drawings do not restrict the invention in any way. More advantages will be explained with examples.

[0046] FIG. 1 is a schematic view of a system according to the present invention.

[0047] FIG. 2 is a schematic view of an effective area, a decoatable are and a portion of a coating system present on a surface of a window according to the invention.

[0048] FIG. 3 illustrates a decoatable area of a decoating apparatus.

[0049] FIG. 4 illustrates a scanning area according to the invention.

[0050] FIG. 5 illustrates a positioning at the zero position.

[0051] FIG. 6 is a schematic view of a frequency selective surface decoated without a protection means.

[0052] FIG. 7 is a schematic view of a protection means.

[0053] FIG. 8 is a schematic view of a frequency selective surface decoated with a protection means as illustrated in FIG. 4.

[0054] FIG. 9 - FIG. 13 illustrate a different embodiments according to the second and / or third aspect of the present invention.

[0055] FIG. 14 represent a decoating apparatus according the invention positioned to decoat in situ a window already mounted on a rapid transit system from the outside of the rapid transit system.

[0056] FIG. 15 represent a decoating apparatus according the invention positioned to decoat in situ a window already mounted on a rapid transit system from the inside of the rapid transit system.

[0057] FIG. 16 illustrates a patchwork of decoated sub-frequency selective surfaces.

[0058] FIG. 17 illustrates a positioning method according to the invention.

[0059] FIG. 18 illustrates a decoating method according to the invention.

[0060] FIG. 19 illustrates a multi portions decoating method according to the invention.

[0061] FIG. 20 illustrates a multi windows decoating method according to the invention.Detailed description

[0062] It is an object of the present invention to alleviate the above described problems and to decoat a window especially when the window is already mounted in a way to that reduces handling while be able to decoat in many location and environments while ensuring the correct positioning of the laser device.

[0063] In this document to a specific embodiment and include various changes, equivalents, and / or replacements of a corresponding embodiment. The same reference numbers are used throughout the drawings to refer to the same or like parts.

[0064] As used herein, spatial or directional terms, such as "inner", "outer", "above", "below", "top", "bottom", and the like, relate to the invention as it is shown in the drawing figures. However, it is to be understood that the invention can assume various alternative orientations and, accordingly, such terms are not to be considered as limiting. Further, all numbers expressing dimensions, physical characteristics, processing parameters, quantities of ingredients, reaction conditions, and the like, used in the specification and claims are to be understood as being modified in all instances by the term "about". Accordingly, unless indicated to the contrary, the numerical values set forth in the following specification and claims are approximations that can vary depending upon the desired properties sought to be obtained by the present invention. In thefollowing description, unless otherwise specified, expression “substantially" mean to within 10%, preferably to within 5%.

[0065] Moreover, all ranges disclosed herein are to be understood to be inclusive of the beginning and ending range values and to encompass any and all subranges subsumed therein. For example, a stated range of "1 to 10" should be considered to include any and all subranges between (and inclusive of) the minimum value of 1 and the maximum value of 10; that is, all subranges beginning with a minimum value of 1 or more, e.g. 1 to 6.1, and ending with a maximum value of 10 or less, e.g., 5.5 to 10. Further, as used herein, the terms "deposited over" or "provided over" mean deposited or provided on but not necessarily in surface contact with. For example, a coating "deposited over" a substrate does not preclude the presence of one or more other coating films of the same or different composition located between the deposited coating and the substrate.

[0066] Where the term “comprising” is used in the present description and claims, it does not exclude other elements or steps. Where an indefinite or definite article is used when referring to a singular noun e.g. "a" or "an", "the", this includes a plural of that noun unless something else is specifically stated. In this document, "configured to (or set to)" may be interchangeably used in hardware and software with, for example, "appropriate to", "having a capability to", "changed to", "made to", "capable of", or "designed to" according to a situation. In any situation, an expression "device configured to do" may mean that the device "can do" together with another device or component.

[0067] F urthermore, the terms first, second and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequence, either temporally, spatially, in ranking or in any other manner. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein. When it is described that a constituent element (e.g., a first constituent element) is "(functionally or communicatively) coupled to" or is "connected to" another constituent element (e.g., a second constituent element), it should be understood that the constituent element may be directly connected to the another constituent element or may be connected to theanother constituent element through another constituent element (e.g., a third constituent element).

[0068] In the following description, unless otherwise specified, expression “substantially” mean to within 10%, preferably to within 5%.

[0069] The following description relates to a system comprising a decoating apparatus and a protection means.

[0070] Especially, FIG. 1 illustrates a system 10 designed to decoat a portion 24 of a coating system 23 present on a surface of a window 2.

[0071] The present invention permits to decoat many type of windows and coating system. The dimensions, the shape, the composition such as borosilicate, sodalime, aluminosilicate glass or alike, the structure of the windows such as single glass sheet, multiple glass sheets, laminated glazing, vacuum glazing, or alike, ••• the number of coating systems present can be managed thanks to the decoating apparatus of the present invention. Each coating system can be treated separately thanks to the system of the present invention.<apparatus>

[0072] According to the invention, the decoating apparatus is designed to decoat a decoatable area 26 of the coating system 23. <Laser device>

[0073] According to the invention, the decoating apparatus comprises a laser device 5. The laser device 5 comprises an optical laser unit (not shown) to generate a laser beam 55. The optical laser unit is designed to decoat a laser zone 59.

[0074] As illustrated in FIG. 4, the laser zone 59 is the area that the laser head is able to decoat into in a fixed position of the laser head meaning when the laser head is not displaced by the displacement means. displacement means>

[0075] According to the invention, the decoating apparatus comprises a displacement means 3. The displacement means 3 is designed to displace the laser device along the decoatable area.

[0076] In some embodiments, the displacement means can comprises motors configured to move said laser device along rails or alike along the X and Y axis meaning substantially parallel to the surface of the window.

[0077] In some other embodiments, the displacement means can comprises a conveyor.

[0078] In some preferred embodiments, the displacement means can comprise an articulated arm designed to displace and to orientate the laser device especially the laser beam substantially normal to the surface of the window to easily decoat a window in situ allowing to avoid to fix a part of the decoating apparatus on the window or on the frame, wall,-- to avoid risks of not be correctly attached and fall or risks to scratch the surface, orticulated arm>

[0079] Preferably, in embodiments with an articulated arm, the decoating apparatus can comprises a body on which the articulated arm is fixed. The articulated arm delocalises the laser device from the body of the decoating device. Said body can comprise an calculation unit to calculate and to control movements of the articulated arm, a generator unit to generate a laser light and to control the laser device and a management unit to manage the calculation unit and the generator unit.

[0080] In some embodiments, the decoating apparatus can further comprise a control unit to interact with the articulating arm and the laser device to be able to move the laser device in space while the laser beam is decoating. The control unit can drive the generator unit to adapt the power, the frequency of the laser light. The control unit can also drive the calculation unit to articulate the articulated arm to move and orientate the laser device to the desired position. The control unit can also drive the optical laser unit to focalise the laser beam and / or to adapt the scanning surface of the laser beam.

[0081] In some preferred embodiments, the decoating apparatus further comprises at least a battery and an inverter to avoid to turn off and restart the decoating apparatus during the displacement between two windows.

[0082] The body can also comprises a power supply to use electricity from the grid.

[0083] The articulated arm comprises at least an articulation to displace the laser device in the space.

[0084] According to some embodiments, the articulated arm can comprises several rotation components such as wrist, elbow, shoulder or alike acting as an articulation. Each of the rotation component can be directly fixed to anotherrotation component or can be fixed using a rigid bar. The rigid bar can have different lengths depending on the desire application.

[0085] In some preferred embodiments, each of the rotation components is driven and controlled by the calculation unit.

[0086] According to the some embodiments, the articulated arm can be designed as a type of mechanical arm that is used for positioning precisely the laser device according to the window shape and geometry and the surface to decoat. The arm may be the sum total of the mechanism allowing either rotational motion or translational displacement of the laser device. These movements are usually programmed, but can be performed by remotely controlling the articulated arm (for instance via a remote, or computer, or tablet), or by piloting the articulated arm via the control panel of the equipment, or by manually moving the laser equipment along the desired movement to let the control unit of the articulated arm acquire this movement, to then repeat it.

[0087] In some preferred embodiments, the articulated arm can allow the laser device to be moved along the 3 axis (cartesian coordinates: X, Y, Z: 1 vertical axis and 2 horizontal one, perpendicular to each other) or rotate around these 3 axis, allowing all 6 degrees of movements, such as all translation and rotation possible in or around each direction, so the amount of articulations of the articulated arm have to be sufficient to allow such movements. Amount of articulations is preferably more than 2, more preferably around 6.

[0088] Preferably, in embodiments with an articulated arm, the laser device is mounted on an end of the articulated arm. In some embodiments in which the decoating apparatus comprises a body, the articulated arm the laser device is mounted on the end opposite to the end fixed to the body. The articulated arm allows the laser device to be moved and oriented in space to decoat correctly the coating system to be decoated.

[0089] According to some embodiments, the length of the laser device of about 180 mm to be able to facilitate the positioning and the movement of the laser device by the articulated arm.

[0090] According to some embodiments, the width of the laser device of about 180 mm to be able to facilitate the positioning and the movement of the laser device by the articulated arm.

[0091] According to some embodiments, the height of the laser device of about 180 mm to be able to facilitate the positioning and the movement of the laser device by the articulated arm.

[0092] In some other embodiments, the dimensions of the laser device can be different such as 100 x 100 x 100 mm depending on the elements comprised inside the laser device and the desired application.

[0093] In some other embodiments, the dimensions of the laser device can be different such as 200 x 200 x 200 mm depending on the elements comprised inside the laser device and the desired application.

[0094] The weight of the laser device is preferably equal to or smaller than about 5 kg to limit the vibration of the articulated arm while avoiding to over dimension said articulated arm while limiting the destabilization risks and jerky movements. <Optical laser unit>

[0095] According to the invention, the laser device 5 comprises an optical laser unit to generate a laser beam 55 from the laser light generated by a generator unit. The laser light is transmitted from the generator unit, disposed in the body to the optical laser unit of the laser device by a cable 405.

[0096] The laser beam is focalised at a focus point 25 on the coating system to decoat when the decoating apparatus is ready to decoat. The laser beam has a specific direction. Preferably, said decoating device can comprise a lens array configured to focus said laser beam at a focus distance.

[0097] The displacement means, especially a articulated arm, allows the laser beam to be substantially normal to the surface of the window at least during the decoating step.

[0098] In the sense of the present invention, the term “normal to the surface" is measured when the laser beam is in a zero position as illustrated in FIG. 4. The zero position 590 is in front of the laser beam when the laser beam is not oriented. The zero position is the (0, 0) point of the scanning area 59 in case of the laser beam can be oriented with an orientation means. The scanning area 59 is defined in positive and negative value centred in the zero position as illustrated in FIG. 4. The displacement means, especially a articulated arm, is able to displace and to orientate the laser device to keep this specific direction of the laser beam. The laser head can be orientate in a XI, Yl, Zl axis, especiallythe laser beam substantially normal at the position zero 590 to the surface of the window.

[0099] In some preferred embodiments, to avoid to have a laser beam with a fixed orientation, to reduce decoating time, the laser device can further comprise an orientation means configured to control the direction of said laser beam 51. In this way, the laser beam scans the portion to be decoated thanks to this orientation means. In such embodiments, the combination between an orientation means and the articulated arm allows to rapidly decoat a large coated portion of a coating system. Preferably, said orientation means may comprise at least a rotatable mirror or a mirror using a galvanometer based motor, to provide a light and fast orientation of the laser beam and to control and manage such orientation.

[0100] In some preferred embodiments, the laser beam generated by the generator unit goes through an optical fibre from the body to the laser device. The laser beam is transformed and shot by the laser device in direction of the surface to decoat. The transformation of the laser beam can be based on reflections by at least one mirror (or more) to go into a Control Unit Adapter (CUA), from where the laser beam can be then emitted toward the glass panel with correct size and shape, and angle and thickness, to remove the coating according to the predetermined pattern.

[0101] The invention permits to very fast remove a large portion of a coating system, for instance to improve the electromagnetic transmission of a window.

[0102] To avoid to adapt the focus point of the laser beam inside the decoated grid, the laser apparatus can comprise a F-theta lens to flatten the focus point on a surface.

[0103] Preferably, the laser apparatus is a pulse laser apparatus and the frequency of the laser beam equals to or is higher than substantially 20kHz.

[0104] In some embodiments, in order to keep the focal point on the coating system, the laser device can comprises a focal device designed to measure the distance between the coating system and the laser device. Measurements are transmitted to the management unit that can drive the laser device and / or the calculation unit and / or a control unit to adapt the focal point on the coating system.

[0105] Preferably, the laser device can comprise a housing to hide and to protect components. The housing comprises an opening in which the laser beam can go out of the laser device.

[0106] In some embodiments, the laser device can further comprise mirror or set of mirrors to aim and redirect laser beam in the correct direction

[0107] In some embodiments, the laser device can further comprise an inclinometer to aim the laser device and the laser beam in the correct direction.

[0108] In some embodiments, the laser device can further comprise c a camera to control the decoating pattern and a light to provide good luminosity to camera.

[0109] In some embodiments, the decoating apparatus can further comprise a protective panel to protect peoples from laser reflected from glass.

[0110] According to the invention, the scanning area 59 is smaller than the portion 24 to decoat.

[0111] The displacement means permits to displace the laser device. Said displacements allows the scanning area 59 to be displaced to form a decoatable area 26.

[0112] The term “decoatable surface”, in the sense of the present invention, means the maximum surface that the decoating apparatus is able to decoat thanks to the laser device and the displacement means without displacing the decoating apparatus itself.

[0113] FIG. 2 shows a window 2 having a coating system 23 on one of its surface. The decoating apparatus is able to decoat a decoatable area 26 different than the portion 24 that can be decoated on the coating.

[0114] Windows can comprises elements such as enamel, security equipment, camera, antennas, or alike that cannot be approached by a laser.

[0115] Thus, the decoatable area cannot be totally scanned by the laser. The laser device can partially decoat only on an effective area 27.

[0116] The term “effective area” in the sense of the present invention means the surface that can be treated by the laser device. This area cannot comprises an area where elements positioned in front cannot be damaged. The decoatable area comprises at least an effective area and a protected area.

[0117] To change the decoatable area to a reduced area, the effective area, apparatus of the prior art needs to change the software to adapt the displacement of the laser head and / or to displace the laser head from a locationto another. Such modifications needs time and to be redone for each shape of effective area.

[0118] According to some embodiments, the surface ratio between the decoatable area and the effective area is smaller than or equal to 30 %; preferably the surface ratio between the decoatable area and the effective area is smaller than or equal to 20 % and more preferably, the surface ratio between the decoatable area and the effective area is smaller than or equal to 15 % to be efficient and to save time.

[0119] According to some embodiments, the surface ratio between the decoatable area and the effective area is equal or greater than to 0.1 %; preferably the surface ratio between the decoatable area and the effective area is equal or greater than to 0.5 and more preferably, the surface ratio between the decoatable area and the effective area is equal or greater than to 1% to be able to efficiently and correctly decoat the correct shape.

[0120] Coming back to FIG. 1, according to the present invention, the system further comprises a protection means designed to be opaque to the wavelength of the laser beam. The protection means is designed to reduce the decoatable area 26 to an effective area 27. There is no need to relocate the decoating apparatus except if the portion to decoat is larger than the decoatable area and no need to reprogram the software to avoid shooting with the laser beam in protected area(s).

[0121] The protection means can be made of any suitable material and / or thickness that is able to be opaque in the sense of the invention to the laser beam.

[0122] In some embodiments, the protection means can be flexible.

[0123] In some other and preferred embodiments, the protection means can be rigid meaning dimensionally stable to ensure the consistency of the decoating.

[0124] In some embodiments, depending on the specific and desire applications, the protection means can be transparent to visible light.

[0125] In some other embodiments, the protection means is opaque to the visible light. The protection means can be made of a plastic-based material such as ABS, PC, PA, or any suitable plastic-based material opaque to the laser beam such as composite or polymers. The protection means can be made of a woodenbased material to reduce carbon footprint. The protection means can be madeof a metal-based material such as aluminum or any other suitable metal-based material. The protection means can be glass-based material. The protection means can be made of any suitable material or assembly of material.

[0126] The outline 92 of the shape of the protection means used to define the effective area can have any shape depending on the specific application.

[0127] That means that the several protection means can be produced. The desire shape is selected and correctly position in front of the decoatable area to obtain the desire effective area.

[0128] FIG. 6 shows an element that cannot be scanned by the laser beam. Said element is inside the decoatable area.

[0129] A first solution of the prior art is to displace the decoatable area to avoid that the decoatable area is in front of said element 46. This first solution reduces the surface that is decoated and thus reduces the EM transparency of the window and the performances.

[0130] Another solution of the prior art is to reprogram the software to avoid the zone in front of said element. This solution needs a lot of time and must be specifically redone for each zone and each shape.

[0131] FIG. 7 illustrates a protection apparatus according to the invention to avoid said problems. The protection apparatus is attached in front of the protected area. The decoating apparatus can normally at least partially decoat without any adaptation. The element is protected by the protection means even if the laser beam is scanning the zone.

[0132] FIG. 8 illustrates the same window than FIG. 6 but treated by the system of the present invention and the protection means of FIG. 7. The zone around the element and the element was not decoated and were protected from the scanning of the laser beam.

[0133] According to the invention, to correctly position in front of the decoatable area to obtain the desire effective area, the protection means 9 comprises an attachment means 91. The attachment means is designed to attach the protection means between the laser device and the window.

[0134] According to some embodiments, the attachment means can be attached on the external surface of the window or on a surface of the object in which the window is placed on. The attachment means is attached in front of the decoating apparatus.

[0135] As illustrated in FIG. 7 and according to such embodiments, the attachment means can comprise a suction pad or alike. Depending on the dimensions and the precision of the protection means, the attachment means can comprises several suction pads. In such embodiments, the attachment means is fixed to the protection means and detachably attached to the window and / or the object and / or around the window such as a frame, a wall, a carbody or a coachwork.

[0136] To detachably attach the attachment means, the attachment means can comprises a tape, a glue, a film or any other suitable material.

[0137] In some embodiments, the protection means and the attachment means can be a single material, such as an adhesive and opaque film, or a multi-layered material.

[0138] In some other embodiments, the attachment means cannot be attached on a surface of the window or the object. The attachment means can comprises a rigid bar attached to the system and especially to the decoating apparatus or positioned stand alone, i.e. positioned on the floor between the decoating apparatus and the object on which the window is.

[0139] In some embodiment, when positioning apparatus is fixed against the window or whatever flat surface, as glass surface of another window or metallic coachwork of a vehicle, the attachment means could be a suction cup, either manual or electric one allowing to create suction into the cup by creating localized void thanks to an electric pump. The attachment means could also be adhesive or magnetic in case of a ferromagnetic metallic coachwork, or mechanic system such as a vise-grips.

[0140] In some embodiments, the laser device 5 can comprise a contact element. The contact element extending from the laser device. The contact element is designed to be positioned between the laser device 5 and a window 2 to treat.

[0141] In some embodiments, the system can comprise a positioning apparatus to correctly position the laser device, especially the scanning area at a starting point.

[0142] As illustrated in FIG. 4 and FIG. 5, the positioning apparatus allows the decoating apparatus especially the laser device to be correctly position at a reference point 242.

[0143] In some embodiments, the reference point 242 corresponds to the position of the laser beam. Preferably, as the laser beam is emitted perpendicularly from the laser device, this reference point is perpendicular to and in front of the laser device.

[0144] In some embodiments when the laser beam can be oriented to scan creating a laser beam scanning area, the reference point can correspond to the centre point of the laser beam scanning area 241 on the coating system to be decoated, this area can also be called the reference area.

[0145] As illustrated in FIG. 7, FIG. 10 and FIG. 12, the attachment means can comprises one or more attachment element such a as suction means to correctly position the positioning means at the desired position while ensuring that this desired position does not change even in the event of an impact.

[0146] FIG. 10 and FIG. 12 illustrate different protection means depending on the protected area of a same window illustrated in FIG. 9.

[0147] The invention permits to easily decoat different shapes of effective area.

[0148] FIG. 10 can be used for example with a security element on the top of the window. The majority of the portion is at least partially decoated with the top central and protected area is not treated as the result illustrated in FIG. 11.

[0149] FIG. 12 illustrate a protection means to protect for example an enamel around the edge of the window.

[0150] The invention permits also easily to decoat a rounded shape as illustrated in FIG. 13 and FIG. 7. Thus rounded shape is optimizing the partially decoated surface 27 while visually avoiding breaking lines. Such optimized rounded shape is not possible by displacing the decoatable area or by modifying the software.

[0151] As illustrated in FIG. 17, the present invention also related to a positioning method 300. The positioning method positions the protection means at the desired location to reduce the decoatable area to the effective area. Said positioning method comprises, for ensuring the correct positioning the protection means a step of installing 301 the protection means between the laser device and the. Said step 301 positions the protection means in a way that when the laser device is positioned and can scan the decoatable area, the protected area is not touched by the laser beam. After the positioning step 301, the positioning method comprises a step 302 of positioning the laser device. This positioning method permits to be sure that the laser device and the laser beamat in correct and desired position directly and with less handling. The laser device is directly positioned to decoat in the portion.

[0152] As illustrated in FIG. 18, to ensure the uniform quality of the decoating over the portion, the present invention also related to a decoating method 400 to at least partially decoat a portion of a coating system present on a surface of a window mounted on a stationary object, for instance a building, or mounted on a mobile object, for instance a vehicle, a rapid transit system such as a train, tram or alike, with a system 10. The decoating method comprises, for ensuring the correct positioning the decoating apparatus at a reference point, a step of positioning 300 the decoating apparatus with the positioning method of FIG. 17.

[0153] Once the decoating apparatus and especially the laser device is correctly position, then then decoating method comprises a step of decoating 401 a frequency selective surface inside the effective area of the coating system.

[0154] In the sense of the invention, the term “decoat” means to modify the continuity of the coating system by removing or by melting for example. The decoating can be a partial decoating especially to create a frequency selective surface.

[0155] The coating system 23 generally uses a metal-based layer and infrared light is highly refracted by this type of layer. Such coating system is typically used to achieve a low-energy multi-glazed window.

[0156] In some embodiment, the coating system can be a heatable coating applied on the multi-glazed window to add a defrosting and / or a demisting function for example and / or to reduce the accumulation of heat in the interior of a building or vehicle or to keep the heat inside during cold periods for example. Although coating system are thin and mainly transparent to eyes.

[0157] U sually, the coating system is covering most of the surface of the multiglazed window 2.

[0158] The coating system can be made of layers of different materials and at least one of these layers is electrically conductive. In some embodiments, for example in automotive windshields, the coating system can be electrically conductive over the majority of one major surface of the multi-glazed window. This can cause issues such as heated point if the portion to be decoating is not well designed.

[0159] A suitable coating system is for example, a conductive film. A suitable conductive film is for example, a laminated film obtained by sequentially laminating a transparent dielectric, a metal film, and a transparent dielectric, ITO, fluorine-added tin oxide (FTO), or the like. A suitable metal film can be, for example, a film containing as a main component at least one selected from the group consisting of Ag, Au, Cu, and Al.

[0160] The coating system may comprise a metal based low emissive coating system. Such coating systems typically are a system of thin layers comprising one or more, for example two, three or four, functional layers based on an infrared radiation reflecting material and at least two dielectric coatings, wherein each functional layer is surrounded by dielectric coatings. The coating system of the present invention may in particular have an emissivity of at least 0.010. The functional layers are generally layers of silver with a thickness of some nanometers, mostly about 5 to 20nm. The dielectric layers are generally transparent and made from one or more layers of metal oxides and / or nitrides. These different layers are deposited, for example, by means of vacuum deposition techniques such as magnetic field-assisted cathodic sputtering, more commonly referred to as "magnetron sputtering". In addition to the dielectric layers, each functional layer may be protected by barrier layers or improved by deposition on a wetting layer.

[0161] The laser apparatus can be oriented to keep the parallelism in case of decoating over a bent section thanks to the articulation of the articulated arm.

[0162] The decoated frequency selective surface comprises decoated segments creating zones where the coating system is still present. Decoated segments can have a width between 15 pm and 150 pm, preferably between 30 pm and 70 pm, and more preferably substantially 50 pm, forming specific designs, such as lines, polygons, hashtag-like, a grid or a like.

[0163] Decoated designs can depend on wanted visual aspect and / or desired wavelength transparency for example.

[0164] Preferably, at least one coating system is present on one interface, meaning one surface of the window 2. Preferably, the coating system is on one of the internal surfaces of the window, surfaces that are not facing the outside of the window.

[0165] Moreover, if the window presents two coating systems applied on two different interfaces, a first coating needs to be decoated before the second one. For example, the decoating apparatus decoats a portion on the closest coating system and then decoats the second one. The focus point is adapted to be on the correct coating system. Preferably, to avoid modifying the decoating of the closest coating, the decoating apparatus decoats a portion on the farthest coating system and then decoats the closest one. The needed power to decoat the farthest one is higher than the needed power to decoat the closest one and risks to degrade the decoated shape of the portion on the closest one if this one is done before the farthest coating.

[0166] Dimensions and shape of the portion to be decoated or the decoated portion depend on the desire application. Thanks to the decoating apparatus of the invention, the decoating apparatus do not necessary be adapted to the dimension of the portion to be decoated and the same decoating apparatus can be used for a large type of windows and environments.

[0167] The position of the decoated portion, and thus the position of the effective area or the effective areas, on the multi-glazed window depends on the application. Preferably, the portion of the coating system to be decoated represents at least 50% of the surface of the coating system, more preferably, the portion of the coating system to be decoated represents at least 70% of the surface of the coating system and even more preferably, the portion of the coating system to be decoated represents at least 80% of the surface of the coating system. It is understood that the portion of the coating system to be decoated and the decoated portion represent a surface of the coating system and not the decoating itself. The present invention permits to decoat a small amount of coating, less than 3%, to improve the transmission of radio waves on a large or not portion of said coating.

[0168] The portion 24 of the coating system to be decoated can be larger than the size of the scanning area. In such embodiments, preferably, the reference point and the reference area correspond to a corner of the portion 24. The laser device is moving to decoat a portion larger than the scanning area.

[0169] In some preferred embodiments, to accelerate the time to decoat a large surface, the frequency selective surface FSS1 can be composed of at least a patchwork of sub-frequency selective surfaces FSS11, FSS12, FSS13, FSS14,FSS21, FSS22, FSS23, FSS24, FSS31, FSS32, FSS33, FSS34 as illustrated in FIG. 16, Therefore, when laser processing is performed on a region larger than a region that can be processed in one process, a pattern formed in a predetermined size that can be processed in one process is formed a plurality of times and continuously arranged. As a result, a continuous pattern can be formed in the entire desired region by connecting decoated tile-like portions like a so-called patchwork.

[0170] In such embodiments, the reference point and the reference area can be any of the sub-frequency selective surfaces. Preferably to simplify and accelerate the decoating steps, the reference point and the reference area is one of the sub-frequency selective surfaces positioned at a corner the portion FSS11, FSS14, FSS31 or FSS34.

[0171] That means that the decoating step 420 can comprises several decoating substeps 421, 422, 423, 424.

[0172] Each of the decoating substeps can be performed by scanning a zone, scanning either via an optical or ultrasonic means for instance, to define the correct shape to the surface to decoat with enough precision, with the laser beam to decoat inside said zone meaning that the orientation of the laser beam is adapted inside said zone. Preferably, the laser device is moving with the articulated arm while the laser beam is scanning to increase the speed of decoating.

[0173] In some embodiments, the laser device can comprise a confocal or any other element designed to scan the surface in front of where the laser beam will be shot, to adjust laser beam position accordingly.

[0174] Preferably, the frequency selective surface is a grid made of decoated segments to form a decoated grid. The grid can be made of a patchwork of subgrids each of the subgrids are connected edge-to-edge.

[0175] In fact, the decoated grids placed in a patchwork manner and connected edge-to-edge allow to create a larger frequency selective surface especially when the decoated grids are created by a decoating apparatus using a galvo head to orientate the laser designed to decoat the coating system.

[0176] Dimensions Lml, Lm2, Lm3, Lm4, W3n, W2n, Win of the sub frequency selective surfaces can depends on the size of the maximum surface that the decoating apparatus can decoat at once and also can depends on the radius ofcurvature around the focal point and the laser parameter such as the scan field, Lmax, and the zone Rayleigh, Za.

[0177] Coming back to FIG. 1, during a decoating step, the laser beam 55 is focalised at a focus point 25 on the coating system 23.

[0178] During a decoating step, the laser device is moving while the laser beam 55 is focalised on the coating system to decoat the coating system.

[0179] In order to correctly decoat a coating system, the laser beam must be precisely focused onto the targeted coating system. Therefore, the position of the coating system must be known with a precision at least three times smaller than the depth of field of the decoating device. The depth of field corresponds to the distance around the focal point of a focused laser beam where the laser beam diameter is considered constant. This distance depends greatly of the laser beam characteristics and the optics used for focusing said laser beam. Typically, the depth of field is around 0.5 mm, which means that the precision on the focus position of the decoating device should be around 0.1-0.2 mm.

[0180] To know the position of the coating system, a confocal unit can be added to the laser device designed to calculate the position of the coating system.

[0181] According to the invention, the decoating method is performed in a factory meaning before to install the treated window.

[0182] Preferably, the decoating method is performed in situ with the decoating apparatus.

[0183] A rapid transit systemlOO comprises several windows 201, 202, 203, 204 in a same row or in several rows as illustrated in FIG. 14.

[0184] According to some embodiments, the decoating method according to the invention permits to perform the decoating method from the inside of the stationary or the mobile object as illustrated in FIG. 14. In such embodiments, the decoating apparatus is position on the floor or on a platform to be correctly positioned. The displacing step can be made by the platform once the decoating apparatus is positioned on the platform. The platform can be a support for the protection means.

[0185] In some embodiments, the decoating method according to the invention permits to perform the decoating method from the inside of the stationary or the mobile object as illustrated in FIG. 15. The decoating apparatus is moved inside the rapid transit system and positioned near a window to be treated.

[0186] Then the present invention also related to a multi portions decoating method 500 as illustrated in FIG. 19. Said multi portions decoating method 500 permits at least partially decoat a larger portion than the decoatable area. A first effective area is decoated using the method 400 and a second effective area is decoated using the method 400 and so on.

[0187] According to the invention, the multi portions decoating method comprises following ordered steps: decoating 301 a frequency selective surface inside the first effective area with the decoating method, and then decoating 301 a frequency selective surface inside the second effective area with the decoating method.

[0188] The number of effective areas per window is not limited.

[0189] It is understood that in some embodiments, the effective area can correspond to the decoatable area if no protection area is present.

[0190] In some preferred embodiments, it is preferable to decoat a row of windows one after the other, the present invention also relates to a multi windows decoating method 600, as illustrated in FIG. 20, to decoat at least a first and a second windows mounted on a stationary object, for instance a building, or mounted on a mobile object, for instance a vehicle, a rapid transit system such as a train, tram or alike.

[0191] The multi windows decoating method comprises following steps decoating a frequency selective surface inside the effective area(s) of the first window with the decoating method and then decoating a frequency selective surface inside the effective area(s) of the second window with the decoating method.

[0192] It is understood that the multi window decoating method is not limited to two windows, a decoating step is performed for each window to decoat. These steps are reproduced as many times as the number of windows to treat.

[0193] The decoating method can comprises a step of placing 402 a decoating apparatus near first window before placing the laser device with the positioning method. Preferably, the decoating apparatus is placed in front of the window to be treated.

[0194] In the sense of the present invention, the term “near” means that the decoating apparatus is not fixed to the windows, the frame or the body of the object on which the window is fixed.

[0195] In some embodiments, the body can be around 70cm from the window to be decoated, preferably placed substantially normal to the window, and with the articulated arm aligned substantially along the main length of the body, or parallelly to the window, with the articulated arm aligned substantially perpendicular to the main body length.

[0196] Preferably, the centre of the articulated arm, which corresponds to the first articulation between the body and the articulated arm, is placed aligned with the centre of the window, the centre along vertical axis, and along the length axis of the window).

[0197] The vertical positioning of the body from the window could be ensured by lifting the body with a lifting equipment, for example a lifting platform, scissor lift platform, “cherry picker” or so on.

[0198] During the decoating step, the articulated arm displaces and orientates the laser device along the portion and keeps the laser beam substantially normal to the surface or to the scanning zone.

[0199] The multi windows decoating method can comprises a step of moving the decoating apparatus to another location to decoat another window or another row of windows or to be stored. The decoating apparatus can decoat a first row of windows 201, 202, 203, 204, 205 and then (or the contrary) decoat a second row of windows 211, 212, 213, 214, 215.

[0200] The multi window decoating method can comprise a step before the step to assemble 701 and / or to provide the decoating apparatus inside or outside the object.

[0201] The multi window decoating method can also comprise a step after all decoating steps to disassemble 702 and / or to retrieve from the object the decoating apparatus.

[0202] The invention also relates to the use a contact element of a laser device comprised in a decoating apparatus according to the first aspect to correctly position the laser device substantially parallel to a window to be decoated while ensuring the uniform quality of the decoating over a portion of a coating system present on a surface of the window.

[0203] Thus, the decoating apparatus of the invention can be used to improve the electromagnetic properties of a multi-glazed window already mounted on astationary object, for instance building, or on a mobile object, for instance a vehicle, a train or alike without dependency to the configuration of the object.

[0204] As illustrated in FIG. 20, the multi portions decoating method and the multi windows decoating method can be mixed. That means that for a stationary object, for instance a building, or mounted on a mobile object, for instance a vehicle, a rapid transit system such as a train, tram or alike having several window to treat, the multi window decoating method is performed and for each window portion can be decoated. Thus, the multi portions decoating method is repeated as many time as needed, then the decoating apparatus is positioned in front a the next window.

[0205] The present invention can decoat a window without manipulations from an operator except maybe some standard manipulations such as the on-off and the first positioning. Especially the laser device and the focal point of the laser beam can move following the profile / geometry of the coating system, whether the window is straight, curved, tilted...

Claims

ClaimsClaim 1. System (10) designed to decoat a portion (24) of a coating system (23) present on a surface of a window (2); the system comprises a decoating apparatus (1) designed to decoat a decoatable area (26) of the coating system; the decoating apparatus comprises a laser device (5) and a displacement means (3); the laser device comprising an optical laser unit to generate a laser beam designed to decoat a laser zone (59); the displacement means designed to displace the laser device along the decoatable area; characterized in that the system further comprises a protection means designed to be opaque to the wavelength of the laser beam and designed to reduce the decoatable area (26) to an effective area (27); and in that the protection means (9) comprises an attachment means (91) designed to attach the protection means between the laser device and the window.Claim 2. System according to claim 1, wherein the surface ratio between the decoatable area and the effective area is smaller than or equal to 30 %; preferably the surface ratio between the decoatable area and the effective area is smaller than or equal to 20 % and more preferably, the surface ratio between the decoatable area and the effective area is smaller than or equal to 15 %.Claim 3. System according to any preceding claims, wherein the surface ratio between the decoatable area and the effective area is equal or greater than to 0.1 %; preferably the surface ratio between the decoatable area and the effective area is equal or greater than to 0.5 and more preferably, the surface ratio between the decoatable area and the effective area is equal or greater than to 1%.Claim 4. System according to any preceding claims, wherein the attachment means comprises a suction pad.Claim 5. System according to any preceding claims, wherein the attachment means comprises a rigid bar.Claim 6. System according to any preceding claims, wherein the displacement means comprises an articulated arm designed to displaceand to orientate the laser device especially the laser beam substantially normal to the surface of the window.Claim 7. System according to any preceding claims, wherein the laser device comprises a F-theta lens.Claim 8. System according to any preceding claims, wherein the laser device comprises a orientation means designed to orientate the laser beam.Claim 9. Decoating method (400) to at least partially decoat a portion of a coating system present on a surface of a window with a system according to any preceding claims; the decoating method comprises following steps: a. Positioning (300) the protection means at the desired location to reduce the decoatable area to the effective area, b. Decoating (401) a frequency selective surface on the decoatable area with the decoating apparatus.Claim 10. Decoating method according to claim 9, wherein the decoating method is performed in situ.Claim 11. Multi windows decoating method (600) to decoat at least an effective area on a first window and an effective area on a second window; each of the windows are mounted on a stationary object, for instance a building, or mounted on a mobile object, for instance a vehicle, a rapid transit system such as a train, tram or alike; the multi windows decoating method comprises following steps:

1. Decoating a frequency selective surface on the first window with the decoating method according to claim 10 with a first protection means,2. Decoating a frequency selective surface on the second window with the decoating method according to claim 10 with a second protection means.Claim 12. Use of a protection means comprised in a system according to any claims 1 - 8 to reduce a decoatable area to an effective area to avoid decoating a non-decoatable zone.

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