Door system with optically switchable windows

Abstract

A door system is disclosed. The door system comprises a door having: a plurality of segments; at least one plastics window in at least one segment of the plurality of segments, wherein the at least one plastics window comprises an electrochromic layer; and a controller which is designed to selectively change a transparency of one or more plastics windows of the at least one plastics window on the basis of an electrochromic effect.

Description

[0001] Gate system with optically switchable windows

[0002] The invention relates generally to the field of garage and industrial doors, and in particular to door systems with optically switchable windows.

[0003] A door, such as an industrial door or a hall door, is used in manufacturing companies (warehouses, intralogistics, industry, logistics centers), critical infrastructure (fire departments, rescue services, police), parking garages and underground car parks, as well as in transport infrastructure (depots, road and motorway maintenance depots, airports). In warehouses and industrial facilities in particular, doors can be used to close large building openings. With such doors, long-lasting functionality is particularly important, as they are often linked to complex production or logistics processes, the interruption of which can result in considerable costs. Robustness and reliable function are therefore required. Depending on the requirements, roller doors, sectional doors, lifting doors, and high-speed doors are used, for example, which open vertically upwards and therefore require little space in front of or behind the entrance.Folding doors are another example. These require more space for the swinging range of the leaves, but can cover a wider area.

[0004] However, in addition to robustness and reliable function, gates often have other requirements. For example, daylight in a hall, a clear view to the outside, and transparency for the public may be desired. One solution to this could be to equip the gates with one or more windows. A disadvantage of these gates with windows is that burglars can quickly gain an overview of the contents of a hall. Another disadvantage is that for emergency services, such as the fire service, large, transparent gates can create a certain proximity to the public, but the privacy of the emergency personnel is not taken into account or is restricted.

[0005] The invention is based on the object of providing an improved door system for working in daylight in halls, taking into account aspects such as security, burglary protection and privacy, sun protection, heat protection, glare protection, UV protection, visual protection, an active alarm signal and bird protection.

[0006] The present invention solves the problems and the object by a door system comprising: a door having a plurality of segments, at least one plastic window in at least one segment of the plurality of segments, wherein each of the at least one plastic window comprises an electrochromic layer, and a controller configured to selectively change a transparency of one or more plastic windows of the at least one plastic window based on an electrochromic effect.

[0007] The subclaims contain further advantageous embodiments of the invention.

[0008] The system according to the invention has the advantage that the transparency of the electrochromatic windows can be adjusted to either allow a clear view of the outside or create a visual barrier, for example, to protect against burglary or to increase the privacy of people in a hall. The electrochromatic windows can be adjusted to suit the situation. The plastic windows provide robust windows that are adapted to the special requirements of movable gate systems.

[0009] Switching the film to a frosted glass appearance can make the glass visible as an obstacle for animals such as birds and provide effective protection against bird strikes. This effectively prevents collisions between birds and the clear glass surfaces of large gate systems. The control system allows the bird protection to be individually regulated or adapted, especially during seasonal bird migration periods.

[0010] In embodiments, the plastic windows comprise double or multiple glazing made of plastic, such as polymethyl methacrylate, styrene-acrylonitrile, or polycarbonate. The double glazing comprises an outer pane and an inner pane. The electrochromic layer can be or comprise an electrochromic film. The electrochromic film can be arranged between the outer pane and the inner pane in the plastic window. The outer pane and the inner pane can be separated from each other by spacers. The electrochromic film can, for example, be applied to the inside of the outer pane. Alternatively, the electrochromic film can be applied to the inside of the inner pane.By using double glazing with the electrochromic layer or film between the panes, the electrochromic layer or film can be protected from damage and dirt, ensuring the longevity of the windows.

[0011] In embodiments, the wall thickness of the outer pane can be at least 3 mm or at least 4 mm. The wall thickness of the inner pane can be at least 3 mm or at least 4 mm. The wall thickness of the outer pane can be greater than the wall thickness of the inner pane. Alternatively, the wall thickness of the inner pane can be greater than the wall thickness of the outer pane. In embodiments, the wall thickness of the inner pane is equal to the wall thickness of the outer pane. The outer pane and / or the inner pane can be provided with a scratch-resistant coating. The coating can be applied to the outer side. The outer pane and / or the inner pane can comprise polymethyl methacrylate, polycarbonate, or styrene acrylonitrile (SAN). With wall thicknesses of at least 3 mm for the inner and / or outer pane, particularly stable and robust windows are provided that can meet the requirements for industrial doors.

[0012] In embodiments, the gate system can comprise at least one sensor. The at least one sensor can be designed to detect at least one signal. The controller can be designed to change the transparency of the one or more plastic windows depending on the at least one signal. The at least one sensor can be designed to detect the presence of a person in an area in front of the gate system or gate. The controller can change the transparency of the one or more plastic windows depending on the presence of the person. Additionally or alternatively, the at least one sensor can be designed to detect the presence of a person in an area behind the gate system or gate. The controller can change the transparency of the one or more plastic windows depending on the presence of the person.In front of the gate system refers to an area on one side of the gate, which can be outside a building in which the gate system is installed. Behind the gate system refers to an area on an opposite side of the gate, which can be inside a building in which the gate system is installed. Additionally or alternatively, the at least one sensor can be designed to detect a direction of movement of a person relative to the gate system. The controller can change the transparency of the one or more plastic windows depending on the direction of movement. Additionally or alternatively, the at least one sensor can be designed to detect an identity of one or more people. The controller can change the transparency of the one or more plastic windows depending on the one or more identities. Additionally or alternatively, the at least one sensor can be designed to measure a light intensity.The controller can change the transparency of the one or more plastic windows depending on the light intensity. Additionally or alternatively, the at least one sensor can be designed to detect sunlight through the at least one plastic window or a part thereof. The controller can change the transparency of the one or more plastic windows depending on the sunlight. Additionally or alternatively, the at least one sensor can be designed to receive a signal from a user's remote control. The controller can change the transparency of the one or more plastic windows depending on the remote control signal. Additionally or alternatively, the at least one sensor can be designed to detect a dangerous situation, such as a gas leak, a fire, or an unwanted change in temperature or pressure.The control system can change the transparency of one or more plastic windows depending on the hazardous situation. Additionally or alternatively, the at least one sensor can be configured to detect a break-in. The control system can change the transparency of one or more plastic windows depending on the detected break-in. In the event of a detected break-in or a detected hazardous situation, the transparency can be changed repeatedly. This can be achieved by repeatedly switching the electrochromic layer on and off.

[0013] Preventive burglary protection can be provided by automatically switching plastic panes to opaque according to a set timer (for example, after the end of the shift every evening at 6:00 p.m. or adjusted daily, always 15 minutes after the start of civil twilight) or when a sensor installed in the immediate vicinity of the gate system detects a light intensity in a predefined area, which may correspond to twilight. Alternatively, the transparency of plastic windows can also be changed by the user via remote control. For example, the transparency can be changed using an app on a smartphone or computer.

[0014] In embodiments, the gate system can comprise a sensor designed to detect the presence of people. When people approach the gate, the intelligent system automatically switches to opaque. The underlying sensor technology can precisely filter and differentiate between objects. For example, a distinction can be made between cross traffic in front of the gate on a road on the one hand and people or vehicles moving towards the gate on the other. This prevents the electrochromic film from unnecessarily switching to opaque. Additionally, the at least one sensor can have a parallel traffic suppression function. This means that the film does not switch for every object that intersects or crosses the sensor area, but simply suppresses unnecessary movement. The operator or user can adjust the sensor's detection field so that only objects of a certain minimum size are detected.

[0015] In embodiments, a continuous change in state of the electrochromic film can create an "on-off" flashing (or flashing in one color) of the electrochromic film, thus sending a clearly visible warning signal. The controller can also change the transparency of the plastic windows based on an alarm signal from a building alarm system. For example, the controller can be connected to a building alarm system. The building alarm system can notify the controller that the building has been broken into or that a dangerous situation has arisen. The controller can continuously change the transparency of the plastic windows as an additional warning signal (in addition to an alarm siren or flashing headlights). A continuous "on-off" flashing of the electrochromic film can send a clear signal to emergency personnel, such as a fire department, to draw attention to an emergency.This can be done in addition to a siren and headlight flasher.

[0016] In embodiments, each of the at least one plastic window is individually connected to the control system via a flexible cable. This enables the individual control of the transparency of each of the at least one plastic window. The individual cabling allows individual windows to be replaced quickly and effectively. The control of the transparency of the plastic windows can be carried out by a door operator, user, or facility manager via an app or desktop version. The control system can comprise a digital control system and can automatically control the transparency of the plastic windows depending on defined scenarios. Individual panes, rows or columns of sections, or the entire plastic glazing area can be flexibly controlled.Based on the detection of sunlight on the door or part of it, individual panes or the entire surface can be intelligently switched on. This allows for beneficial optimization of the building's climate. Furthermore, glare for users on the inside of the hall can be counteracted.

[0017] The transparent setting of the electrochromatic windows allows natural daylight and warmth into the building and allows visual contact with the outside. The disadvantage of transparent glazing from a structural perspective is that heat and solar radiation cannot be controlled. The space behind the doors can become uncomfortably hot when exposed to sunlight. By switching to opaque, the heating of the hall during intense sunlight (e.g., in summer) can be counteracted. The intelligent sensor technology saves costs, energy, and CO2 by reducing the energy required for air conditioning. The sensor technology can be designed to detect a value corresponding to solar radiation. If this value, such as light intensity or temperature, exceeds a specified threshold, the control system can change the transparency of plastic windows.For example, glare protection can be activated to improve energy efficiency by minimizing the building's overheating. In the cold season, this effect can be reversed. The hall can be further tempered using solar radiation by setting the transparent glass.

[0018] In embodiments, the door is an industrial door, such as a sectional door, a folding door, a high-speed door, a stacking door, a lift-folding door, a hangar door, a fabric lift door, or a shipyard door. The transparency of each plastic window of the at least one plastic window can be changed by means of the electrochromic layer so that a privacy screen is optionally switched on or off. The privacy screen can comprise individual windows or entire door surfaces. Adjacent segments of the plurality of segments of the door can be hinged together to move the door from a closed position to an open position and from the open position to the closed position. The cables connecting each of the at least one plastic window to the control unit can be combined in a cable harness.The control system can additionally be configured to move the gate from the closed position to the open position and from the open position to the closed position. The gate can include an integrated door, for example, a wicket door. The gate can be configured with a bottom-side stabilizing element, at least in the area of ​​the door. The door can include a plastic window of the at least one plastic window.

[0019] In embodiments, the controller is configured to automatically change the transparency of each plastic window of the at least one plastic window using the electrochromic layer after a predetermined interval following a last transparency change. By automatically activating the electrochromic windows within a specific time, the longevity of the windows can be increased. The interval can be 72 hours or less. An interval of 72 hours or less increases the longevity of the windows without overly impacting operation. A user can set the interval. For example, the user can select specific days of the week and / or times of day for the interval.

[0020] The present invention further solves the problems and the object addressed by a method for producing a planar structure. The method comprises the steps of applying an electrochromic layer to a first plastic pane; producing a plastic window with double glazing using the first plastic pane with the electrochromic layer and a second plastic pane; inserting the plastic window into a planar structure; and electrically connecting the plastic window to a controller for changing a transparency of the plastic window using the electrochromic layer.

[0021] In embodiments, a wall thickness of the first plastic disc is at least 2 mm, at least 3 mm, at least 4 mm, or at least 5 mm. A wall thickness of the second plastic disc can be at least 2 mm, at least 3 mm, at least 4 mm, or at least 5 mm. The planar structure can be or comprise a partition element or a gate, preferably an industrial gate as specified in more detail above.

[0022] The system according to the invention can be further improved by additional, individually advantageous embodiments. Technical features of the individual embodiments can be combined with one another as desired and / or omitted, provided that the technical effect achieved by the omitted technical feature is not important.

[0023] The present invention will be described in more detail below with reference to exemplary drawings. The drawings show examples of advantageous embodiments of the invention.

[0024] They show:

[0025] Figure 1 is a schematic representation of a door system according to the invention with optically switchable windows according to one embodiment, and

[0026] Figure 2 shows a flow diagram of a method for producing a planar structure, for example a gate system with optically switchable windows according to one embodiment.

[0027] Figure 1 shows a door system 100. The door system comprises a door 110. In Figure 1, a sectional door is shown as door 110 as an example. Alternatively, the door can also be a folding door, a high-speed door, a stacking door, a folding door, a hangar door, a fabric lift door, or a shipyard door, or a combination of these.

[0028] The door comprises a plurality of segments 120a-d. The door may comprise two or more segments. For example, the door may comprise four, six, eight, ten, twelve, twenty, or more segments. At least one plastic window 140 is installed in at least one of the segments 120a-d. In Figure 1, four windows 140 are installed in each of the segments 120a-d, by way of example. The number of installed windows 140 may vary from segment to segment.

[0029] The plastic windows 140 include electrochromic materials to control the transparency of the windows. Each plastic window 140 is electrically connected to a controller 130. The controller 130 is configured to change the transparency of the electrochromic plastic windows. For example, by applying or removing a voltage to the electrochromic layer or film, a window 140 can transition from a transparent state to an opaque state. Thus, the plastic window can be selectively used as a privacy screen or a transparent window. For clarification, the door can also include simple plastic windows that do not include electrochromic materials, whose transparency therefore cannot be controlled.An electrochromic effect occurs when molecules and crystals in an electrochromic layer or film change their optical properties due to an external electric field or current flow.

[0030] Adjacent segments 120a and 120b of the plurality of segments of the door may be hinged together to move the door from a closed position to an open position and from the open position to the closed position. The cables connecting each of the at least one plastic window to the controller 130 may be combined in a cable harness. The controller 130 may be configured to move the door from the closed position to the open position and from the open position to the closed position.

[0031] The segments 120a-d of the door 110 may comprise individual sections or panels extending horizontally or vertically to the ground, which are interconnected by means of pivoting joints along a corresponding horizontal or vertical axis so that the door can be guided along a track for opening or closing the door. The track may be a non-straight track.

[0032] The gate 110 includes an integrated door 150. The gate can be configured with a bottom-side stabilizing element, at least in the area of ​​the door 150. The door 150 can include a plastic window, such as plastic window 140, with an electrochromic coating.

[0033] Figure 1 shows a plurality of electrochromic plastic windows 140. The electrochromic plastic windows 140 comprise electrochromic materials. The electrochromic materials can be arranged in the plastic windows 140 as a layer. For example, the electrochromic materials can be contained in a film. The film can be arranged between a double glazing of the plastic windows 140. Each of the plastic windows 140 is electrically connected to the controller 130. The controller 130 can be connected to the plastic windows 140 via at least one flexible cable harness, for example a flexible ribbon cable. Each electrochromic plastic window 140 can comprise two bus bars that are in electrical connection with the electrochromic film. The cables from the two bus bars can lead into a flexible cable harness or be part of the flexible cable harness.The busbars can be located on two opposite sides of the plastic window 140. The controller 130 is configured to apply an electrical voltage to the busbars to change the optical properties of the electrochromic film. A cable harness of the at least one cable harness can comprise a plurality of conductor wires running parallel to one another on the same plane. For example, all plastic windows of a segment can be connected to a single cable harness. All plastic windows of another segment can be connected to a single other cable harness. The ends of the cables of the cable harness can comprise plug contacts or magnetic connectors for connecting to the plastic window 140 and to the controller 130.

[0034] The cable harness can be or include a ribbon cable. These have advantages, including the ability to provide multiple parallel wires for transmitting power, communication signals, etc., in a thin, flexible format.

[0035] In embodiments, the gate 110 includes two or more electrochromic plastic windows 140. The cables are configured to establish electrical contact between each of the electrochromic plastic windows 140 and the controller 130. In an example with two electrochromic plastic windows 140, each with two power rails, a ribbon cable with four parallel conductor wires can be used to establish electrical contact and supply power to the electrochromic plastic windows 140 as needed.

[0036] The controller 130 may be configured to control or change the position of the door. For example, the door system 100 may include components for opening or closing the door 110. In one embodiment, the controller 130 may control the transparency of electrochromic plastic windows 140 of a particular segment 120a. For example, the plastic windows 140 of one segment 120a may be converted to a privacy state, whereas the plastic windows 140 of another segment 120d remain in a transparent state.

[0037] The controller 130 can control the plastic windows in response to user input to selectively change the transparency of the at least one plastic window. The input can be manual and / or wireless (e.g., via a remote control). Changing the transparency of the plastic windows can include a color change. The plastic windows can take on a color such as blue, red, yellow, and / or green by applying a voltage.

[0038] Figure 2 shows a flow chart of a method 200 for producing a planar structure, for example a gate system.

[0039] In a first step 210, an electrochromic layer is applied to a plastic pane. The electrochromic layer can be applied as a film to the inside of a plastic pane. For example, the film can be laminated to the plastic pane. This can be done under clean room conditions. The thickness of the plastic pane can be at least 2 mm, at least 3 mm, at least 4 mm, or at least 5 mm. The outer side of the plastic pane can be coated with a scratch-resistant coating. In one embodiment, the total thickness of the assembled plastic window is at least 2 mm.

[0040] In a further step 220, the plastic window is assembled. This involves assembling the plastic pane with the electrochromic layer from step 210 with another plastic pane, creating a plastic window with double glazing consisting of two plastic panes. The electrochromic layer is arranged between the two plastic panes.

[0041] In step 230, the assembled plastic window is installed into a flat structure, such as a door. The door can be or include a garage door or industrial door. The plastic window can be installed into an existing door. For example, an old window in the door can be replaced with the assembled plastic window. This allows door systems to be retrofitted with electrochromic plastic windows. Alternatively, the plastic windows can also be installed in new doors.

[0042] In step 240, each electrochromic plastic window, including the assembled plastic window, is electrically connected to a controller for controlling the electrochromic plastic windows. Each plastic window can be connected to a resilient wiring harness. The plastic windows are permanently connected to the controller.

[0043] Electrochromatic glass, also known as switchable or intelligent glass, offers the possibility of automatically dimming windows. Electrochromatic glass utilizes the property of electrochromatic materials to change the light transmission depending on the applied direct current. For example, applying a low voltage can produce a bluish tint. When electrical charges are transferred to a microscopically thin coating (e.g., tungsten trioxide, polyaniline), it becomes optically active and changes color. This process can last from a few seconds to several minutes. If no voltage is applied, the glass retains its current color.

[0044] Electrochromic glass can be used in automotive engineering for anti-dazzle rearview mirrors and in building glazing for temperature control. The use of electrochromic glass can be a significant cost factor. Therefore, electrochromic glass is often used only in well-protected or immobile areas.

[0045] Aspects of the present invention relate to movable door systems with electrochromic films. Use in movable door systems subject to the Machinery Directive imposes special requirements regarding the use of glazing in the sections and the wiring of the windows. These requirements are advantageously met by the use of plastic windows according to the embodiments described above. The movable door systems can be electrically operated. The electrical control used for this purpose can advantageously be extended according to the invention to control electrochromic plastic windows.

[0046] The electrochromic plastic windows for doors in the designs described above are versatile and robust. The electrochromic plastic windows can be used both for new doors and as a retrofit solution for existing door systems. This solution can be used for all types of doors, including sectional doors, folding doors, high-speed doors, and lift-and-fold doors. The switchable electrochromic layer / film allows for flexible switching from opaque glazing to clear plastic window surfaces at the touch of a button.

[0047] The electrochromic layer / film can be switched from matte white (= privacy protection) to nearly transparent (varies depending on the viewing direction) at the touch of a button. This allows for daylight-bright working conditions in the halls, a clear view to the outside, and visibility for citizens to be combined with improved burglary protection and the desired privacy of emergency personnel. Colors other than white are also possible. For example, the electrochromic film can be switched from transparent to a color dependent on the film material, such as red, green, blue, or a combination of the primary colors.

[0048] The electrochromic film, which contains a liquid crystal film, consumes little power. The film can be controlled via a transformer with, for example, 65 volts (tolerance + / - 5%). As soon as the voltage is switched on via remote control or wired control, the film becomes transparent. However, when the voltage is switched off, the frosted privacy screen is maintained.

Claims

CLAIMS 1. A gate system (100) comprising: a gate (110) having a plurality of segments (120a-d); at least one plastic window (140) in at least one segment (120a-d) of the plurality of segments (120a-d), wherein each of the at least one plastic window (140) comprises an electrochromic layer; and a controller (130) configured to selectively change a transparency of one or more plastic windows (140) of the at least one plastic window (140) based on an electrochromic effect.

2. Gate system according to claim 1, wherein at least one, preferably each of the at least one plastic window comprises a double or multiple glazing made of plastic, and wherein the double or multiple glazing comprises an outer pane and an inner pane.

3. A door system according to claim 2, wherein the electrochromic layer comprises an electrochromic film, and wherein the electrochromic film is arranged between the outer pane and the inner pane of the plastic window.

4. Gate system according to one of claims 2 to 3, wherein the wall thickness of the outer pane is at least 2 mm, at least 3 mm or at least 4 mm, and / or the wall thickness of the inner pane is at least 2 mm, at least 3 mm or at least 4 mm.

5. A gate system according to one of claims 2 to 4, wherein the wall thickness of the outer pane is greater than the wall thickness of the inner pane; and / or wherein the outer pane and / or the inner pane is provided with a scratch-resistant coating, and / or wherein the outer pane and / or the inner pane comprises polymethyl methacrylate, polycarbonate, or styrene-acrylonitrile (SAN).

6. Gate system according to one of claims 1 to 5, comprising at least one sensor, wherein the at least one sensor is designed to detect at least one signal, and wherein the control is designed to change the transparency of the one or more plastic windows depending on the at least one signal.

7. Gate system according to claim 6, wherein the at least one sensor is designed to: detect the presence of a person in an area in front of and / or behind the gate system, wherein the controller is designed to change the transparency of the one or more plastic windows depending on the presence of the person; detect the direction of movement of a person relative to the gate system, wherein the controller is designed to change the transparency of the one or more plastic windows depending on the direction of movement; detect the identity of one or more people, wherein the controller is designed to change the transparency of the one or more plastic windows depending on the one or more identities; measure a light intensity, wherein the controller is designed to change the transparency of the one or more plastic windows depending on the light intensity;to detect solar radiation through the at least one plastic window or a part thereof, wherein the controller is designed to change the transparency of the one or more plastic windows depending on the solar radiation; to receive a signal from a user's remote control, wherein the controller is designed to change the transparency of the one or more plastic windows depending on the remote control signal; to detect a dangerous situation, wherein the controller is designed to change the transparency of the one or more plastic windows depending on the dangerous situation, preferably the transparency is repeatedly changed when a dangerous situation is detected;and / or to detect a break-in, wherein the control is designed to change the transparency of the one or more plastic windows depending on the detected break-in, preferably to change the transparency repeatedly when a break-in is detected.; 8. Gate system according to one of claims 1 to 7, wherein at least one, preferably each of the at least one plastic window is individually connected to the control system by means of a flexible cable; and / or wherein the transparency of the one or more plastic windows of the at least one plastic window is changed such that a privacy screen is selectively switched on or off.

9. Gate system according to one of claims 1 to 8, wherein the control is designed to change the transparency of all plastic windows of a segment individually, and / or wherein the control is designed to change the transparency of the one or more plastic windows depending on a predefined time and / or the course of the sun.

10. Door system according to one of claims 1 to 9, wherein the door is an industrial door, and wherein the industrial door is preferably one of the following doors: a garage door; a sectional door; a folding door; a high-speed door; a sliding door; a stacking door; a lift-folding door; a hangar door; a fabric lift door; and a shipyard door.

11. A gate system according to any one of claims 1 to 10, wherein adjacent segments of the plurality of segments of the gate are hingedly connected to one another to form the gate from a closed position into an open position and from the open position into the closed position, wherein each of the at least one plastic window is connected to the control by means of at least one cable, wherein the at least one cable is combined in a cable harness, and wherein the control is designed to bring the door from the closed position into the open position and from the open position into the closed position.

12. Gate system according to one of claims 1 to 11, wherein a door (150) is integrated in the gate, wherein the gate is preferably formed with a bottom-side stabilizing element at least in the region of the door (150), and wherein the door (150) comprises a plastic window or at least one plastic window.

13. Gate system according to one of claims 1 to 14, wherein the control is designed to change the transparency of at least one, preferably each plastic window of the at least one plastic window automatically after a predetermined interval has elapsed after a last transparency change.

14. A method (200) for producing a planar structure, the method (200) comprising the following steps: Applying (210) an electrochromic layer to a first plastic disc; Producing (220) a plastic window with double glazing using the first plastic pane with the electrochromic layer and a second plastic pane; Inserting (230) the plastic window into a flat structure; electrically connecting (240) the plastic window to a control for changing a transparency of the plastic window by means of the electrochromic layer.

15. The method according to claim 14, wherein a wall thickness of the first plastic disc is at least 2 mm, at least 3 mm, at least 4 mm or at least 5 mm; and / or wherein a wall thickness of the second plastic disc is at least 2 mm, at least 3 mm, at least 4 mm, or at least 5 mm; and / or the planar structure comprises a separating element or a gate, preferably an industrial gate.

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