WO2024251618A1 - System comprising a decoating apparatus and associated methods for decoating a portion of a coating on a window - Google Patents

Abstract

The present invention discloses a system comprising a decoating apparatus (10) and designed to correctly position the decoating apparatus (10) at a reference point. The decoating apparatus (10) is designed to decoat a portion of a coating system (23) present on a surface of a window (2).The decoating apparatus (10) further comprises an articulated arm (3) and a laser device (5), comprising an optical laser unit to generate a laser beam (55), mounted on an end of the articulated arm (3). The articulated arm (3) is designed to displace and orientate the laser device (5) substantially parallel to the surface of the window (2). The laser device (5) comprises a contact element (52) extending from the laser device (55). The system further comprises a positioning apparatus (9) comprising a first abutment means, the positioning apparatus (9) being designed to receive the contact element (52) into abutment against the first abutment means. The present invention also relates to decoating methods and use.

Description

SYSTEM COMPRISING A DECOATING APPARATUS AND ASSOCIATED METHODS FOR DECOATING A PORTION OF A COATING ON A WINDOW

Description

Technical Field

[0001] The present intention relates to a system comprising a decoating apparatus. The system is designed to correctly position the decoating apparatus at a reference point.

[0002] The present invention further relates to a positioning method for ensuring the correct positioning the decoating apparatus at a reference point.

[0003] The present invention further 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.

[0004] 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

[0005] 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.

[0006] 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.

[0007] 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.

[0008] 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.

[0009] 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.

[0010] Usually, 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.

[0011] A treatment can be a laser scribing or like, or preferably a decoating of a coating system.

[0012] 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.

[0013] 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 A /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 frequency selective 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.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] 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 the window. 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.

[0019] On top of that, such system needs to move the whole laser device. This movement is complicated, dangerous and implies heavy elements such as motors. [0020] In another domain, US6,559,411 describes an apparatus for laser scribing a tin oxide layer coated on a glass panel substrate.

[0021] 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. Moreover, the position of the laser is adjusted in the Z direction during the laser scribing to maintain the focusing on said tin oxide layer.

[0022] However, this focusing requires a precise and complete understanding of the glass panel substrate including the thickness of each layer and the position of said tin oxide layer as well as the knowledge of the exact distance between the conveyor and the laser.

[0023] Laser beam of prior art is always placed and fixed orthogonally to the surface to be decoated. To create a decoated surface the decoating apparatus must be displace along said surface using motors and complex drive systems.

[0024] 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.

[0025] 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.

[0026] 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 is completely unknown. It is therefore impossible for such apparatus to focus the laser properly on the coating system.

[0027] 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.

[0028] 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, •••

[0029] 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.

[0030] Hence, an ongoing technical issue is to obtain a decoating apparatus and process that can be used on multiple kind of multi-glazed windows, 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 multiglazed window is already mounted on an object while accessibility is limited by limiting operators handlings.

Summary of invention

[0031] The present invention relates, in a first aspect, to a system. Said system comprises a decoating apparatus. The system is designed to correctly position the decoating apparatus at a reference point. The decoating apparatus is designed to decoat a portion of a coating system present on a surface of a window. The decoating apparatus further comprises an articulated arm and a laser device. The laser device comprises an optical laser unit to generate a laser beam The laser device is mounted on an end of the articulated arm. The articulated arm is designed to displace and to orientate the laser device substantially parallel to the surface of the window, especially the laser beam substantially normal to the surface of the window.

[0032] Preferably, the frequency of the laser beam equals to or is higher than substantially 20kHz.

[0033] The solution as defined in the first aspect of the present invention is based on the laser device comprises a contact element extending from the laser device.

[0034] The solution as defined in the first aspect of the present invention is also based on the system further comprises a positioning apparatus comprising a first abutment means, the positioning apparatus being designed to receive a part of the laser device into abutment against the first abutment means.

[0035] The present invention also relates, in a second aspect, to a positioning method for ensuring the correct positioning the decoating apparatus at a reference point. The positioning method comprises following steps:

Al. Installing the positioning apparatus to position the first abutment means in front of the window

A2. Positioning the contact element into abutment against the first abutment means

[0036] The present invention also relates, in a third aspect, 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, with a system according to the first aspect of the present invention. The decoating method comprises, for ensuring the correct positioning the decoating apparatus at a reference point, following steps:

A. Positioning (300) the decoating apparatus according to the positioning method of claim 8, B. Decoating (401) a frequency selective surface inside the portion of the coating system.

[0037] The present invention also relates, in a fourth aspect, to a multi portions decoating method at least partially decoat a first portion and a second 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 according to the first aspect of the present invention. The positioning apparatus comprises a second abutment means. The first abutment means is designed to correct positioning the decoating apparatus at a reference point of the first portion of the window and the second abutment means is designed to correct positioning the decoating apparatus at a reference point of the second portion of the window. The multi portions method comprises following ordered steps :

- Decoating a frequency selective surface inside the first portion with the decoating method according to the third aspect of the present invention,

- Decoating a frequency selective surface inside the second portion with the decoating method according to the third aspect of the present invention.

[0038] The present invention also relates, in a fifth aspect, to a multi windows decoating method 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. The multi windows decoating method comprises following steps:

- Decoating a frequency selective surface inside the portion of the first window with the decoating method according to the third aspect of the present invention,

- Decoating (301) a frequency selective surface inside the portion of the second window with the decoating method according to the third aspect of the present invention.

[0039] The present invention also relates, in a sixth aspect, to an use of positioning apparatus comprised in a decoating apparatus and a contact element; the positioning apparatus comprises a first abutment means to correctly position the decoating apparatus at a reference point to correctly decoat a portion of a coating system present on a surface of a window (2); the decoating apparatus further comprises an articulated arm (3) and a laser device (4), comprising an optical laser unit to generate a laser beam, mounted on an end of the articulated arm; the articulated arm being designed to displace and orientate the laser device substantially parallel to the surface of the window; the laser device comprises the contact element extending from the laser device; the positioning apparatus being designed to receive the contact element into abutment against the first abutment means.

[0040] 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, •••

[0041] 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.

[0042] 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, •••

[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 a positioning apparatus position in front of a window according to the invention.

[0048] FIG. 3 is a schematic view of a zoom of FIG. 2.

[0049] Each of the FIG. 4, FIG. 5, FIG. 6 and FIG. 7 represents a positioning apparatus according some embodiments of the present invention.

[0050] FIG. 8 illustrates a window with several section and a positioning apparatus comprising a first abutment means and a second abutment means.

[0051] FIG. 9 illustrates a schematic 3D view of the positioning apparatus of FIG. 8.

[0052] FIG. 10 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.

[0053] FIG. 11 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.

[0054] FIG. 12 illustrates a patchwork of decoated sub-frequency selective surfaces.

[0055] FIG. 13 illustrates a positioning method according to the invention.

[0056] FIG. 14 illustrates a decoating method according to the invention.

[0057] FIG. 15 illustrates a multi portions decoating method according to the invention.

[0058] FIG. 16 illustrates a multi windows decoating method according to the invention.

[0059] FIG. 17 illustrates a multi windows - multi portions decoating method according to the invention.

Detailed description

[0060] 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.

[0061] 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.

[0062] 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 the following description, unless otherwise specified, expression “substantially” mean to within 10%, preferably to within 5%.

[0063] 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.

[0064] 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.

[0065] Furthermore, 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 the another constituent element through another constituent element (e.g., a third constituent element).

[0066] In the following description, unless otherwise specified, expression “substantially” mean to within 10%, preferably to within 5%.

[0067] The following description relates to a decoating apparatus but it’s understood that the invention may be applicable to any laser apparatus to treat a surface of a window mounted in situ. Preferably, the laser apparatus is a decoating apparatus and the laser device is designed to decoat at least partially a portion of a coating system presents on a surface of the window.

[0068] Especially, FIG. 1 illustrates a system 100 designed to correctly position the decoating apparatus at a reference point. The system comprises a positioning apparatus 9 and a decoating apparatus. In FIG. 1, only a part of a decoating apparatus 1 according to the invention is shown and especially a part of an articulated arm 3 and a laser device 5 in front of a window 2 comprising two glass sheets and a coating system 23. The window has two external surfaces 21, each of the external surface is facing outside of the window. [0069] According to some embodiments, the decoating apparatus can comprises a body on which the articulated arm is fixed. 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.

[0070] 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.

[0071] 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.

[0072] The body can also comprises a power supply to use electricity from the grid. orticulated arm>

[0073] The articulated arm is designed to displace and orientate the laser device while avoiding 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.

[0074] The articulated arm delocalises the laser device from the body of the decoating device.

[0075] The articulated arm comprises at least an articulation to displace the laser device in the space.

[0076] 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 another rotation component or can be fixed using a rigid bar. The rigid bar can have different lengths depending on the desire application.

[0077] In some preferred embodiments, each of the rotation components is driven and controlled by the calculation unit. [0078] According to the invention, the articulated arm is 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.

[0079] 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.

<Laser device>

[0080] According to the invention, the decoating apparatus comprises a laser device 5.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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. [0085] 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.

[0086] 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.

[0087] 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. cOptical laser unit>

[0088] The laser device 5 comprises an optical laser unit to generate a laser beam 51 from the laser light generated by the 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.

[0089] The laser beam is focalised at a focus point 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.

[0090] The articulated arm allows the laser beam to be substantially normal to the surface of the window at least during the decoating step.

[0091] In the sense of the present invention, the term “normal to the surface” is measured when the laser beam is in the zero position. The zero position 590 is in front of the laser beam when the laser beam is not orientable. The zero position is the (0, 0) point of the scanning area 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. 1. The 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, especially the laser beam substantially normal at the position zero 590 to the surface of the window.

[0092] In some preferred embodiments, to avoid to have a laser beam with a fixed orientation, 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.

[0093] 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.

[0094] The invention permits to very fast remove a large portion of a coating system, for instance to improve the electromagnetic transmission of a window.

[0095] To avoid to adapt the focus point of the laser beam inside the decoated grid, the laser apparatus comprises a F-theta lens to flatten the focus point on a surface.

[0096] Preferably, the laser apparatus is a pulse laser apparatus and the frequency of the laser beam equals to or is higher than substantially 20kHz.

[0097] 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.

[0098] 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.

[0099] In some embodiments, the laser device can further comprise mirror or set of mirrors to aim and redirect laser beam in the correct direction

[00100] In some embodiments, the laser device can further comprise an inclinometer to aim the laser device and the laser beam in the correct direction. [00101] 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.

[00102] In some embodiments, the decoating apparatus can further comprise a protective panel to protect peoples from laser reflected from glass. <contact element>

[00103] The laser device 5 comprises a contact element 52. 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 as illustrated in FIG. 1.

[00104] According to some embodiments of the invention, the contact element can comprise an external surface 523 having a radius of curvature Re. The external surface is concave meaning an inwardly rounded shape. The radius of curvature, Re, of the external surface of the contact element is smaller than or equal to the radius of curvature, Rw, of the external surface of the window in front of the portion (Re < Rw).

[00105] In some preferred embodiments, the contact element can comprise a fixing member. The fixing member is designed to be fixed on the laser device and around the opening in which the laser beam is going out of the laser device.

[00106] In some preferred embodiments, the contact element can comprises at least an spacer 522 to separate the external surface 523 of the contact element with the laser device from a defined distance from the external surface of the window.

[00107] In some preferred embodiments, the contact element can comprises at least a contact member 524. The contact member defines the shape of the external surface 523.

[00108] In some preferred embodiments, the external member is made of a soften material than the material of the fixing member. The soften material is designed to prevent scratch or other damage that physical contact of the device could create on the window to be decoated. The material could be rubber, resin, Teflon, Ertalon, or any other material suitable to prevent scratch or other damage that physical contact could create.

[00109] In some preferred embodiments, the contact element comprises an opening through which the laser beam can pass. More preferably, the opening is wider than the laser beam scanning area. [00110] The external member can have many shape such as an external member has a generic U-shape or generic donuts shape or any hollow polygonal shape, such as hollow rectangular shape. The shape can also be made of two bars or pins for example.

[00111] In some embodiments, the contact element can comprises at least three spacers. The spacer permits to define a distance between the laser device and the external surface while giving a rigidity to the contact element.

[00112] Preferably, the fixing member and the at least one space are made of a rigid material. The rigid material would preferably be metal based material, for instance aluminium to limit the total weight of the device or plastic based material such as PC or ABS or PA or any other material suitable to keep the physical stability of a fixing member.

[00113] In some preferred embodiments, to reduce waste while be able to decoat several windows, the contact element can have a fastening means to removable fasten the external member to the contact element.

Positioning apparatus>

[00114] According to the invention, the system further comprises a positioning apparatus 9 as illustrated in FIG. 2. At least a part of the position apparatus is position in front of the window.

[00115] According to the invention, the positioning apparatus comprises a first abutment means. The positioning apparatus being designed to receive the contact element into abutment against the first abutment means.

[00116] The first abutment means is designed to receive a part of the contact element into abutment against.

[00117] As illustrated in FIG. 3, the positioning apparatus allows the decoating apparatus especially the laser device to be correctly position at a reference point 242.

[00118] 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.

[00119] 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.

[00120] According to some embodiments, the first abutment means can comprise a first 92 rigid member and a second 93 rigid member. Each of the first and second rigid members are designed to receive the contact element into abutment against. In such embodiments, the contact member is positioned in abutment against the first rigid member and the second rigid member.

[00121] According to some preferred embodiments, dimensions are smaller than 400mmx400mm, more preferably around about 150x150mm.

[00122] In some embodiments, the height of first rigid member 92 and width of second rigid member 93 are creating a generic rectangular frame which dimensions are preferably the external dimensions of the contact element 52, preferably smaller than 200x200mm, more preferably around about 120x100mm. [00123] Preferably to correctly position the laser device, the first abutment means has a shape corresponding to the shape of the part of the contact element that can be positioned in abutment.

[00124] In the sense of the invention, the term “rigid” means that the first and the second members cannot be substantially forced out of shape.

[00125] In some embodiments, the first and the second members can be elongated rectangular generic shape to simplify the manufacture of the positioning means.

[00126] In some embodiments, the window can comprise more than one portion to decoat. Several positioning apparatus can be used, one positioning apparatus for a portion. The positioning apparatus can also comprise a second abutment means 97. The first abutment means 96 is designed to correct positioning the decoating apparatus at a first reference point of the window to be decoated and the second abutment means 97 is designed to correct positioning the decoating apparatus at a second reference point of the window to be decoated as illustrated in FIG. 6 and FIG. 7.

[00127] It is understood that the second abutment means can have the same characteristics as described for the first abutment means.

[00128] FIG. 8 illustrated a window comprising several sections 231, 232, 233 and at least one section 232 comprises a non-infinite radius of curvature Rw. A portion on the section 231 and a portion of the section 232 need to be treated. [00129] In such embodiments as illustrated more in detailed in FIG. 9, the positioning apparatus can also comprise a first abutment means 96 to correctly position the laser device on the reference point of the first portion of the section 233 and a second abutment means 97 to correctly position the laser device on the reference point of the first portion of the section 232.

[00130] In some preferred embodiments, the surface of the positioned apparatus in contact with the is designed to following the window shape. Said surface can be flat, or curved for curved glass as illustrated in FIG. 9

[00131] The positioning apparatus can be comprises a attachment means 91 to detachably attach the positioning apparatus at a defined position especially the attachment means is designed to removable attach the first abutment means at the desired position and in front of the window to be at least partially decoated. The attachment means can comprises a suction pad or any other means to detachably attach a positioning means at a defined position. The attachment means can depend on the material on which it will be attach.

[00132] Preferably, the abutment means is following the window shape.

[00133] In some embodiments, the attachment means allows quick mounting and demounting on the window or around the window such as a frame, a wall, a carbody or a coachwork.

[00134] 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.

[00135] As illustrated in FIG. 4 - FIG. 9, 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.

[00136] As illustrated in FIG. 13, the present invention also related to a positioning method (300). The positioning method allows the decoating apparatus and specifically the laser device to be correctly positioned at a reference point. Said positioning method comprises, for ensuring the correct positioning the decoating apparatus at a reference point a step Al of installing 301 the positioning apparatus allowing to position the first abutment means in front of the window. Said step Al positions the positioning apparatus in a way that when the contact element is in abutment against the abutment means the laser beam is correctly positioned at the reference point. Then, the positioning method comprises a step A2, after the step Al, of positioning 302 the contact element into abutment against the first abutment means. This positioning method permits to be sure that the laser device and the laser beam at in correct and desired position directly and with less handling. The laser device is directly positioned to decoat in the portion.

[00137] As illustrated in FIG. 14, 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 A of positioning (300) the decoating apparatus with the positioning method of FIG. 13.

[00138] 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 portion of the coating system.

[00139] 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.

[00140] 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.

[00141] 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. [00142] Usually, the coating system is covering most of the surface of the multiglazed window 2.

[00143] 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 causes issues such as heated point if the portion to be decoating is not well designed.

[00144] 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.

[00145] 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.

[00146] Ion some embodiments, because the external surface of the contact element is smaller than or equal to the radius of curvature, Rw, of the external surface of the window in front of the portion, only a part of the contact element can be against the surface. [00147] In the sense of the invention, the term “against” means that at least a part of the surface is in contact with the external surface of the window and preferably at least borders.

[00148] Thanks to the contact element of the present invention, a good selection of the radius Re can allow to decoat a large number of different curved glazing without changing contact element or a part of it.

[00149] Preferably, before or in the same time that the step Bl, the decoating method can comprises a step of placing the decoating apparatus to a first working position.

[00150] In the sense of the invention, the term “working position” means a position in which the decoating apparatus is able to decoat the portion of the coating system while the laser device is substantially perpendicular to the tangent at the focal point of the coating system to decoat. That means that the decoating apparatus can stay at a position and only the laser device is moved to a new position.

[00151] As illustrated in FIG. 3, 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.

[00152] As illustrated in FIG. 8, a window can comprises several sections with different radius of curvature. The radius of curvature is measured at the surface of the glass panel where the coating system is disposed on. A flat portion has an infinite radius of curvature.

[00153] The decoating apparatus according to the invention is able to decoat using the decoating method a window having different bent sections at once or executing the decoating step at each sections.

[00154] In case of multiple curvature or different windows with different curvature, it is preferred to have a radius Re smaller than or equal to the smallest curvature of said sections and windows.

[00155] 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. [00156] Decoated designs can depend on wanted visual aspect and / or desired wavelength transparency for example.

[00157] 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.

[00158] 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 to modify 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.

[00159] 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.

[00160] The position of the decoated portion 25 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.

[00161] Coming back to FIG. 2, 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.

[00162] 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. 12, 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.

[00163] 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.

[00164] That means that the decoating step 420 can comprises several decoating substeps 421, 422, 423, 424.

[00165] 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.

[00166] In some embodiments, the laser device can comprises 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.

[00167] 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. [00168] 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.

[00169] 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 of curvature around the focal point and the laser parameter such as the scan field, Lmax, and the zone Rayleigh, Za.

[00170] 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.

[00171] 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.

[00172] 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.

[00173] To know the position of the coating system, a cofoncal unit can be added to the laser device designed to calculate the position of the coating system.

[00174] According to the invention, the decoating method is performed in a factory meaning before to install the treated window.

[00175] Preferably, the decoating method is performed in situ with the decoating apparatus.

[00176] A rapid transit systemlOO comprises several windows 201, 202, 203, 204 in a same row or in several rows as illustrated in FIG. 10.

[00177] 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. 10. 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.

[00178] 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. 11. The decoating apparatus is moved inside the rapid transit system and positioned near a window to be treated.

[00179] Windows 211-215 illustrated in FIG. 10 can corresponds to window of FIG. 8 with at least a curved section 232.

[00180] Then the present invention also related to a multi portions decoating method 500 as illustrated in FIG. 15. Said multi portions decoating method 500 permits at least partially decoat a first portion and a second 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 according to any preceding claims, wherein the positioning apparatus comprises a second abutment means; the first abutment means is designed to correct positioning the decoating apparatus at a reference point of the first portion 410 of the window and the second abutment means is designed to correct positioning the decoating apparatus at a reference point of the second portion 420 of the window.

[00181] According to the invention, the multi portions decoating method comprises following ordered steps : decoating 301 a frequency selective surface inside the first portion with the decoating method, and then decoating 301 a frequency selective surface inside the second portion with the decoating method.

[00182] Said multi portions decoating method permits to rapidly correctly position the laser device at the reference point for each portion to be decoated. The contact element is positioned for a first portion then the decoating step is performed inside this portion. Then the contact element is positioned for the second portion and the decoating step is performed inside this second portion.

[00183] The number of portions per window is not limited.

[00184] 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. 16, 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.

[00185] The multi windows decoating method comprises following steps decoating a frequency selective surface inside the portion of the first window with the decoating method and then decoating a frequency selective surface inside the portion of the second window with the decoating method.

[00186] 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.

[00187] 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.

[00188] 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.

[00189] 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.

[00190] Preferably, the center 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).

[00191] 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.

[00192] 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.

[00193] 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.

[00194] 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.

[00195] 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.

[00196] 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.

[00197] Thus, the decoating apparatus of the invention can be used to improve the electromagnetic properties of a multi-glazed window already mounted on a stationary 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.

[00198] As illustrated in FIG. 17, 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.

[00199] 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

Claims

Claim 1. SystemlO comprising a decoating apparatus and designed to correctly position the decoating apparatus at a reference point 241, the decoating apparatus being designed to decoat a portion 24 of a coating system present on a surface of a window (2); the decoating apparatus further comprises an articulated arm (3) and a laser device (4), comprising an optical laser unit to generate a laser beam, mounted on an end of the articulated arm; the articulated arm being designed to displace and orientate the laser device, especially the laser beam substantially normal to the surface of the window,; characterized in that the laser device comprises a contact element extending from the laser device and in that the system further comprises a positioning apparatus comprising a first abutment means, the positioning apparatus being designed to receive the contact element into abutment against the first abutment means.

Claim 2. System according to claims 1, wherein the first abutment means comprises a first rigid member and a second rigid member; each of the first and second rigid members are designed to receive the contact element into abutment against.

Claim 3. System according to any preceding claims, wherein the positioning apparatus comprises an attachment means designed to removable attach the first abutment means at the desired position and in front of the window to be at least partially decoated.

Claim 4. System according to any preceding claims, wherein the positioning apparatus comprises a second abutment means; the first abutment means is designed to correct positioning the decoating apparatus at a first reference point of the window to be decoated and the second abutment means is designed to correct positioning the decoating apparatus at a second reference point of the window to be decoated.

Claim 5. System according to any preceding claims, wherein the laser device comprises a F-theta lens.

Claim 6. System according to any preceding claims, wherein the laser device comprises the laser device comprises a orientation means designed to orientate the laser beam.

Claim 7. System according to any preceding claims, wherein the contact element comprises an opening through which the laser beam can pass.

Claim 8. Positioning method (300), the positioning method comprises, for ensuring the correct positioning the decoating apparatus at a reference point, following steps:

Al. Installing (301) the positioning apparatus to position the first abutment means in front of the window

A2. Positioning (302) the contact element into abutment against the first abutment means

Claim 9. 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 according to any preceding claims; the decoating method comprises, for ensuring the correct positioning the decoating apparatus at a reference point, following steps:

A. Positioning (300) the decoating apparatus according to the positioning method of claim 8,

B. Decoating (401) a frequency selective surface inside the portion of the coating system.

Claim 10. Decoating method according to claim 9, wherein the decoating method is performed in situ.

Claim 11. Multi portions decoating method (500) at least partially decoat a first portion and a second 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 according to any preceding claims, wherein the positioning apparatus comprises a second abutment means; the first abutment means is designed to correct positioning the decoating apparatus at a reference point of the first portion (410) of the window and the second abutment means is designed to correct positioning the decoating apparatus at a reference point of the second portion (420) of the window, the multi portions method comprises following ordered steps:

- Decoating (301) a frequency selective surface inside the first portion with the decoating method according to claim 9,

- Decoating (301) a frequency selective surface inside the second portion with the decoating method according to claim 9.

Claim 12. Multi windows decoating method (600) 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; the multi windows decoating method comprises following steps:

- Decoating a frequency selective surface inside the portion of the first window with the decoating method according to claim 9,

- Decoating (301) a frequency selective surface inside the portion of the second window with the decoating method according to claim 9.

Claim 13. Use of a positioning apparatus comprised in a decoating apparatus and a contact element; the positioning apparatus comprises a first abutment means to correctly position the decoating apparatus at a reference point to correctly decoat a portion of a coating system present on a surface of a window (2); the decoating apparatus further comprises an articulated arm (3) and a laser device (4), comprising an optical laser unit to generate a laser beam, mounted on an end of the articulated arm; the articulated arm being designed to displace and orientate the laser device substantially parallel to the surface of the window; the laser device comprises the contact element extending from the laser device; the positioning apparatus being designed to receive the contact element into abutment against the first abutment means.