Display panel, particularly for interchangeable traffic signs

Abstract

A new design for an outdoor display panel with a pixel grid and focused light emission, particularly for variable message signs, is proposed. Such displays must meet specific standards to emit clearly recognizable graphic images or symbols under all weather conditions, remaining functional in all types of sunlight, heat and cold, storms, thunderstorms, rain, and snow. These displays either have a large housing or are assembled from identical modules on a support frame. While a single large housing offers technical advantages in this application, it is difficult to implement. The presented design uses a perforated substrate (1) as the housing front and plastic tiles (21) with pixel optics (24) embedded in the grid, which are bonded to the substrate (1) without gaps and with a seal.The optics (24) protruding through the perforated grid are illuminated internally by LED boards (41) with LEDs (42), which are also arranged in the grid and aligned with the optics (24) via positioning pins (4). They are pressed evenly against the optics (24) by springs (48). The mounting plate (1) is stiffened by longitudinal and transverse struts (5, 6) and welded to the housing, forming a Faraday cage. An alternative version of the mounting plate (1) made of perforated profiles (11) arranged in a row is also presented, as well as a module (51) constructed with the same elements, the same size as the LED board (41), which can be used for modular displays.

Description

[0001] Variable message signs have long been widely used in traffic control and information and have been implemented using LED technology for decades. They display switchable symbols and text, as well as graphics and even video sequences, and are subject to numerous standards for use in the road network, which stipulate their use outdoors under all traffic, visibility, and weather conditions, especially under direct sunlight. They differ from general display boards and screens in their focused, bright light emission and their mechanical resistance to damage and vandalism. They operate in relatively open, unattended conditions, yet are electronically monitored, and must reliably convey legally relevant information to road users.For this purpose, they use light points consisting of an LED light source with collecting optics, which are arranged individually in symbols or in a grid as so-called pixels for graphic representations in individual light colors, or controllable color values ​​for image representation, and emit their light in a bundled manner towards the road users.

[0002] Since screens are often too small, far too dark, and not weatherproof for this purpose, and a protective casing impairs visibility, specialized designs have been developed for such displays. These can be divided into two groups. On the one hand, the displays form the front of a housing that is manufactured to the appropriate size and contains all the necessary components such as power supplies, cable harnesses, control and monitoring, cooling, heating, and ventilation, as well as mechanically adjustable suspensions. The largest housings extend across all lanes of a highway, are accessible for maintenance, and are delivered by special transport. On the other hand, displays are modular in design, with each module containing all the components and auxiliary units required for operation, and the required number of modules are mounted in a grid on a correspondingly large support frame.The modules are connected to each other and optionally to a connection cabinet using a variety of cable connections and sealed connectors.

[0003] Both designs have specific advantages and disadvantages. Common to all versions is the display surface, which appears black when switched off and can reach considerable temperatures in strong sunlight, in addition to the comparatively lower LED energy required to display the image. The color and brightness values ​​of the LEDs are temperature-dependent and must be compensated for by adjusting their control if necessary. Heat dissipation from the display surface is therefore an important criterion, not only because of the LEDs, but also because of the optics and materials used and the resulting problems with varying thermal expansion behavior and sealing. In particular, different heating levels in some areas, for example due to the displayed image content, or partial shading of the display panel, can be expected, which can lead to further thermal stresses within the device.

[0004] A shared enclosure offers the great advantage of equalizing the temperature between the hot, sunlit and cooler halves of the enclosure, allowing for free internal convection and external convection cooling, provided this is supported and not hindered. An empty enclosure with a black front surface never gets too hot for an LED display, regardless of the sun's position. If the display is implemented in an energy-efficient and thermally efficient manner, additional cooling is often unnecessary. In such an enclosure, significantly improved internal convection can still be achieved with just a few fans, especially if the display surface is not vertical.

[0005] A display module, on the other hand, is too small for free internal convection. The heat must be distributed via conduction and dissipated via external convection, with the functionally necessary internal components presenting further obstacles to heat flow. Therefore, it must be distributed and dissipated primarily using aluminum or die-cast parts via a rear panel with cooling fins, or the light output may be reduced. The modules, along with the connectors and sealing effort, are also relatively expensive compared to exposed, wired LED boards in a large housing. However, even a layperson can replace the module in the event of damage.

[0006] The historical development of variable message signs, from individual optics with incandescent lamps and later fiber optic bundles to individual LED optics, has provided for a metallic front plate, which is part of the device housing and contains the mounting holes for the optics. A front panel for sealing has proven to be ineffective due to solar reflections, fogging, or damage. Therefore, designs are still in use and even specified in which individual optics are inserted, pressed (as described in EP0757268A1 [Swarco]), or glued (as mentioned in EP1593109A1 [Swarco]) into a blackened metallic front plate with punched openings; a front panel is undesirable. The fully assembled front plate is then inserted into the housing.For larger devices, the front panel must be supported against a supporting structure behind it within the housing using studs located at the corners of the LED boards. For even larger devices, several such front panels are glued together using metal strips that also have holes or cutouts for the pre-installed optics. Using additional brackets located on the front panel or the optics, the LED boards are mounted aligned with the optics and connected to each other, power supplies, and control boards via open-ended cables. The LED boards themselves are the defining, modular components; like the optics and the front panel itself, they are located directly in the convection flow of the ambient air within the housing.

[0007] This design typically produces a uniformly illuminated surface due to uniform cooling, whereas modules with a housingless design often produce noticeable fielding of the display due to varying heat dissipation and heat distribution, also because the pixel pitch across the module boundaries often cannot be precisely maintained. Furthermore, a common housing with a metallic front also forms a Faraday cage to protect the built-in electronics from direct lightning strikes, which can be quite relevant for typical display sizes and high, overhead mounting positions in open fields.

[0008] The visual, thermal, and electrical advantages of a metallic front panel with sealed optics come at the cost of significant disadvantages. Blackening can only be achieved through surface treatments such as anodizing, painting, or powder coating. Each process presents specific problems such as spotting, adhesion, scratching, or relatively high solar reflection, as well as dimensional changes in the optics mounting holes. Punching or drilling the grid holes leads to denting, bulging, and bending of the front panel, making alignment difficult. Handling panels equipped with optics is space-consuming and, without a transport frame, can damage them through bending and twisting. Automatic optics assembly requires large gantry robots with additional units such as sorters, presses, and cameras for process monitoring, as well as significant assembly time due to long travel distances.Added to this is the problem of different expansion coefficients of the metallic front panel and the sealed plastic optics, which over time can lead to stress relief in the plastic parts, embrittlement of seals, detachment of adhesives and thus to leaks, loosening and even twisting of the optics, while permanently elastic adhesives have proven very effective for connecting and sealing even large components.

[0009] There have been discussions for some time about redesigning the front panel and assembly, but this amounts to a redesign and therefore requires at least another impetus, such as a change in standards, a more suitable LED, a better process, or a different manufacturer. EP1227458A2 (Zelisko), for example, describes a module made of transparent plastic containing an LED board, mounted in a grid on a perforated front surface using a seal, and with a black coating on the inside to protect against solar reflections. However, this module thus represents a light-transmitting connection between all the optics, which is qualitatively disadvantageous, and it also lacks a Faraday cage.

[0010] Modular displays on carrying frames are primarily manufactured in China, as can be seen from patents CN115394208A and CN207572010U. They are only a marginal topic here and none of them feature a Faraday cage.

[0011] The object of the invention was a cost-effective, modular design of the mostly vertical display surface of a variable message sign in any size, while maintaining a sealed individual housing and complying with all relevant mechanical, lighting and environmental standards.

[0012] The invention is now characterized in thatthe display surface of the housing comprises a metallic flat carrier plate which is stiffened by longitudinal and transverse struts and firmly connected to the housing and has an opening for each optic as well as fitting holes for positioning pins, that this carrier plate is formed by preferably rectangular or square plastic tiles in which the optics are tightly inserted in a grid arrangement, which also have positioning pins and a surrounding edge with a support surface as an adhesive surface, along which they are glued precisely and tightly to the carrier plate, wherein the optics protrude inwards through the openings of the carrier plate, and that LED boards fitting from the inside between the longitudinal and transverse struts are precisely aligned via the protruding positioning pins and their fitting holes onto the optics into which they radiate their light and are thereby aligned by means of spring bridges,which are locked between the longitudinal or transverse struts or attached to the positioning pins, are pressed against the optics under defined pre-tension.

[0013] In other words, the optics are not mounted directly into the metal front; this merely forms a longitudinally and transversely stiffened support and mounting surface with through holes in the optics grid, thus requiring no black coating. It is completely covered by rectangular or square tiles made of black plastic, in which the optics are tightly mounted in the grid and extend through to the rear. After the adhesive is applied, these tiles are aligned along their peripheral edges using their positioning pins to the registration holes and tightly glued to the carrier plate. Segments of the carrier plate or extensions of the longitudinal struts and their positioning holes are placed directly under the permanently elastic adhesive and are also sealed.The result is a dense black front with the optics. The plastic surface is geometrically designed with roof prisms, studs, microprisms, or micro-holes, so that sunlight falling on it is either directed into irrelevant areas or reflected little to not at all and largely absorbed, thus achieving a much better result than with a black coating. A small functional gap exists between the tiles to accommodate any varying thermal expansion of individual tiles relative to the metal carrier plate.

[0014] On the inside of the support plate, the optics protrude through the openings. They are precisely positioned using the positioning pins, along with the LED boards provided with matching holes, which fit between the longitudinal and transverse struts. To ensure that the LEDs remain permanently in contact with their optics with virtually no gaps and minimize light transmission losses, springs connected to rigid bridges press against the LED board at suitable points. These bridges are snapped into suitable openings in the longitudinal struts or fixed to the positioning pins with lock washers or adhesive. The cabling can now begin, with the cables or other components being attached along the longitudinal and transverse struts.

[0015] It is obvious that the tiles, the LED boards, and the support plate stiffeners are all subordinate to a higher-level design grid so that any device size can be manufactured modularly and cost-effectively. This design grid is based on economically and technically advantageous part sizes, the required pixel grid, and the electronic requirements of the LED addressing and control components. For example, a typical pixel grid of 20 mm results in a module element with 8x8 = 64 optics and a size of 160x160 mm. However, an LED board can also have more LEDs, such as 128 or even 256 LEDs, which can reduce the number of cable connections. The longitudinal and transverse struts are then spaced 320 mm apart everywhere, for example. The use of large and small LED boards together can also be made electrically possible.The design grid then determines the appropriate size for the entire display panel. Of course, each common pixel grid requires its own components and design grid specifications, with the optics used in each grid.

[0016] The size and thickness of the longitudinal and transverse struts depend on structural requirements, particularly the maximum wind force acting on the device. In the area of ​​the LED boards, they are only sheet metal thick, but can be better stabilized further inside, for example, by means of beveling. They not only feature positioning holes and tenons, but also air vents near the support plate to promote internal convection. They can be placed on the support plate and joined securely and with minimal distortion by spot welds or laser welding. Generally, aluminum sheet is recommended for the housing and all metal components, with stainless steel being an option for chemically demanding locations, such as tunnels or coastal areas.

[0017] For the enclosure itself, a circumferential C-shaped frame profile is recommended. This is mitered to form a rectangular enclosure frame, into which the carrier plate fits precisely and is spot-welded from the inside together with the longitudinal and transverse struts. The rear consists of one or more adjacent maintenance doors. Housings that can be opened as a single unit are also possible. In enclosure technology, numerous well-tested designs are available, including all components. If the enclosure is painted or powder-coated, a light color should be used for thermal reasons, and the enclosure should be coated before the carrier plate is installed. Welding positions should be covered or subsequently sanded to a bright finish; the carrier plate should be bare and free of grease for reasons of dimensional accuracy, particularly because of the positioning and fitting holes and adhesive adhesion.Weld spots should be placed and executed in such a way that the coating is only affected in a small, invisible area.

[0018] The tiles, LED boards and their cabling can also be used to produce modules with a few additional parts, so that this market can also be served.

[0019] The invention will now be described in detail using various illustrations and some embodiment variants.

[0020] It shows FIGS. 1 A and 1 B clearly shows a corner of the housing frame including the continuous stiffened support plate from the outside and inside, FIGS. 2 A and 2 B the same with a support plate made of U-profiles, FIG. 3 clearly a tile including the optics to be fitted, FIG. 4 A the fully loaded tile from the front and FIG. 4 B from behind, FIG. 5 a clear illustration of a tile after the adhesive has been applied, FIGS. 6 A and 6 Ba fully equipped device corner with a continuous stiffened support plate from the outside and inside, FIGS. 7 A and 7 B clearly the same with a support plate made of U-profiles and with alternative spring bridges, FIG. 8 clearly shows a modular version of the invention from behind and FIG. 9 A horizontal section through this module. For all design illustrations, tiles with 6x6 optics and a tight 12mm pixel pitch were used, allowing for a clearer representation than actual production designs. Larger pixel pitches offer more space but may require additional supports and mountings for the larger components.

[0021] FIG. 1 AShows the metallic components in the area of ​​a device corner and their connection by means of marked weld points in a design with a continuous support plate of the usual or required sheet thickness. The housing is enclosed by a circumferential housing profile 9 with mitered corners, which forms the opening on its front side for installing the agreed display in the dimensions of the used design grid. The support plate 1 is inserted slightly recessed into this opening. It has openings 2 for each optic in the agreed pixel grid. Furthermore, it contains rectangular positioning holes 3 for securing the stiffening longitudinal struts 5 and round fitting holes 4 for later receiving the positioning pins 23 of the tiles 21.

[0022] FIG. 1 Bshows the same corner from the inside. It is assumed that the housing is lying with the opening facing downwards on a welding table and that the inserted carrier plate 1 is held at this height on a base plate with the thickness of the recess d. First, the longitudinal struts 5 are inserted with their extensions 5a into the positioning holes 3 and connected flush to the carrier plate 1 with weld spots 10, then the cross struts 6 with their recesses 6a are inserted into the recesses 5b of the longitudinal struts 5 and welded together. The longitudinal struts 5 have large ventilation holes 8 near the carrier plate 1 and, if required, rectangular locking holes 7 for snapping in spring bridges (46), as well as possibly further fastening holes for built-in components. Finally, the carrier plate 1 itself is connected all around to the adjacent legs of the housing profile 9 by means of weld spots 10. The housing is then ready for optical and electrical assembly.Of course, the support plate 1 can also be welded to the longitudinal and transverse struts 5 and 6 beforehand. TIG and laser welding are well-known, clean technologies available that also ensure a good electrical connection between all metallic components and can be used regardless of the material.

[0023] FIGS. 2 A and 2 Bpresent a design variant that is particularly recommended for larger devices. The support plate is formed here by perforated U-shaped support profiles 11 arranged side by side, which are continuously manufactured on punching and rolling lines and cut to length as required, or extruded profiles with subsequent perforation. They can also be offset against each other to form continuous longitudinal stiffening. Their width corresponds to the design grid, and the leg heights to the required stability. They have continuous edges 12, which are necessary to support the adhesive beads. They have not only the optics openings 2 in the hole grid and the fitting holes 4, but also large ventilation holes 13 near the edges 12, as well as recesses 14, into which the cross struts 6 engage with their recesses 6a. This construction is also held together by means of weld points 10.If required, locking holes 7 can also be introduced into the legs, but alternative spring bridges are to be demonstrated here.

[0024] Especially with large devices, the housing, as well as its mounting, must withstand considerable forces and deformation, which may necessitate a completely different design, for example, incorporating shaped tubes. This may also require the cutting of sections and struts. In any case, however, the display requires a sturdy, surrounding frame for protection and to secure the display. This frame often also serves as a contrast bezel, and the front of the frame is then coated in black.

[0025] In FIG. 3is an enlarged view of a tile 21 with the optics holes 22 for the optics and an optic 24 before pressing in. Both tile 21 and optic 24 have a contact surface 25, which is shown cylindrical here. Here, the optic 24 has a rib 27 which projects into a groove 26 and ensures correct alignment. Before pressing in, a drop of adhesive could be applied to one of the surfaces 25, or the optic is simply pressed in with a slight excess until it rests against the contact surface 30. The tile 21 can be heated up and the optic 24 cooled to facilitate pressing in. The contact surfaces 25 can also be more complex, for example with a non-circular shape instead of a rib for orientation, or slightly conical or with multiple sections so that the tile does not bulge due to the effect of the sealing forces.The durability of the joint is achieved by using materials with the same thermal expansion coefficient. Therefore, the tiles are preferably made of black polycarbonate, and the optics of highly transparent Plexiglas. These materials have proven their superior resistance to weathering, particularly against yellowing due to UV light, for decades, and have very similar temperature expansion behavior.

[0026] The front of tile 21 is provided with a structure 28 that reduces solar reflection while still being somewhat easy to clean. This structure serves to suppress sunlight falling on it for an observer of the display in order to comply with normative contrast requirements. Even with a rough structure, black polycarbonate has a certain surface gloss, similar to a powder coating produced by melting, and as a flat surface, it creates excessive reflection; therefore, additional deflection and absorption structures are necessary. The structure shown here consists of roof prisms that reflect a portion of the sunlight upwards and, especially when the sun is low in the sky, almost completely absorb its rays by scattering them multiple times within the prism grooves.

[0027] FIG. 4 Aclearly shows a tile 21 fully equipped with optics 24, the front of which is provided with the structure 28. It has a circumferential edge 30 of constant height. Equipping the tile 21 with optics 24 is a relatively easy-to-automate process.

[0028] FIG. 4 Bshows the same tile 21 from the back. The surrounding edge 30 is part of a flat contact surface 31 for the carrier plate. It has small contact nubs 33 all around, which ensure a minimum gap for the adhesive 32. Furthermore, long, slightly conical positioning pins 23 are visible. They serve to precisely position the tile on the carrier plate and are arranged asymmetrically to allow only the correct mounting position. The optics 24 are protected by protective tubes 29 from damage and from contamination by displaced adhesive. They also provide optical shielding between the optics from stray LED scattered light or penetrating sunlight, preventing glare between the pixels.The ends of the protective tubes 29 protrude slightly beyond the ends of the optics 24 and thus not only cover slit light between the LEDs and the optics ends, they also provide additional centering of the LEDs on the optics.

[0029] FIG. 5clearly shows the adhesive 32 applied to the contact surface 31 along the peripheral edge 30, which represents a semi-automated process for assembly. The highly viscous, black polyurethane- or polymer-based adhesive remains permanently elastic after curing. Larger tiles 21 may also have additional positioning pins 23, and the contact surface 31 may also have ribs further inside, where adhesive is also applied to achieve better adhesion and prevent subsequent warping of the tile. The contact studs 33 ensure a minimum thickness of the adhesive, which can thus elastically follow the small temperature-related shifts between the tile and the carrier plate.

[0030] FIG. 6 A shows the mounting of the display in the corner area of ​​a device with a continuous support plate 1 clearly from the outside, Fig. 6b from the inside. If an automated adhesive application takes place Fig. 5instead, only one tile 21 is inserted next to the other, determined by the positioning pins 23, which only fit into the fitting holes 4 of the carrier plate 1 at the correct positions, and pressed on, whereby the adhesive 32 is slightly displaced and the entire area under the tile 21 is sealed against the carrier plate 1 and the already existing adjacent tiles.

[0031] When applying the adhesive by hand, the adhesive 32 only needs to be sprayed diagonally into the existing edges of the installation position. The tile 21 is then placed onto it and the adhesive 32 is pressed into place, creating a good seal. For the first tile, the adhesive 32 is sprayed into the edge of the housing profile 9. The remaining exposed sides of the tile are sealed during installation of the adjacent tile by spraying the adhesive into the edges. The adhesive also creeps into the gaps created by the attachment studs 33 and is additionally pressed into place during installation of the adjacent tile. A functional gap 34 is created between the tiles, which absorbs the greater thermal expansion of the tiles compared to the metallic carrier plate 1 and prevents significant internal stresses.

[0032] For the majority of tiles, applying adhesive at an angle to two edges is sufficient during installation. Only for the last tiles is a U-shaped application necessary, and for the last tile, an application to all four edges is necessary. For large tiles, additional adhesive points can also be provided within the tile. To secure the tiles against denting or detachment, standard locking rings can be pushed onto the positioning pins from behind, or thread-forming nuts can be screwed on, or the positioning pins can simply be fixed with adhesive relative to the carrier plate 1.

[0033] After the adhesive has hardened, the LED boards 41 are inserted between the longitudinal and transverse struts 5 and 6, inserted with their locating holes 45 onto the positioning pins 23, and pressed onto the tiles 21. The LEDs 42 protrude into the protective tubes 29 until they rest against the optics 24. This position is maintained by spring bridges 46, which snap into the locking holes 7 of the longitudinal struts 5 and, with their springs 48, elastically press onto the LED board 41 at regular intervals to ensure that all LEDs 42 rest easily against the optics 24, despite any curvature of the LED board 41. Excessive pressure could push the optics out of the tiles or deform them before the protective tubes 29 even come into contact with the LED board 41. The functional components 43 and the connector 44 are arranged on the back of the LED board 41 so that they do not get caught under the springs 48. Two or more plug-in connections may also be present.

[0034] In FIG. 6 BYou can see how the LED board 41 is positioned approximately centrally to the ventilation holes 8. This allows convection air to flow between the carrier plate 1 and the LED board 41, as well as to the rear of the board, where it cools the LED board 41 and functional components 43. There is also plenty of space for convection air between the cross braces 6 and the LED board 41, allowing the front panel to be installed vertically or horizontally in the device. Likewise, you can see the generous space for cabling and additional components, as well as the easy accessibility. This makes a defective LED board 41 or component easy to replace. But tiles 21 can also be replaced after removing the LED board 41; one cuts the circumferential functional gap 34 of the tile to be replaced free with a knife blade up to the carrier plate 1, presses this with the protective tubes 29 forwards until the adhesive 32 tears, cleans the free space of adhesive residues and glues in a new tile 21.This requires access to the device from both inside and outside.

[0035] FIG. 7 A and FIG. 7 B clearly show the design with support profiles 11, also from the outside and inside. No longitudinal struts are required, as the stiffening is provided by the profile legs with ventilation holes 13; however, the same cross struts 6 are required. The edges 12 of the support profiles 11 lie directly under the bonding of the tiles 21 and are sealed with the adhesive 32. The installation of the tiles 21 is carried out in the same way as previously described.

[0036] FIG. 7 Bshows the LED board 41, which is also mounted in the same way as before. However, here it is pressed against the optics 24, which are mounted on the positioning pins 23, by spring bridges 47 with springs 48 under slight preload. These spring bridges can be secured using commercially available retaining rings, thread-forming nuts, or simply with adhesive. For this purpose, the LED board 41 also requires free areas on its back between the functional components 43 and the connector 44, where the springs 48 can press. The spring bridges 46 and 47 are preferably made of fiber-reinforced plastic in order to maintain the spring forces across the temperature range and over time. Here, too, one can see the position of the LED board 41 in relation to the ventilation holes 13, which allow good access for circulating air, and the free space between the LED board 41 and the cross struts 6, as well as the space for cabling and additional components.Replacing LED boards and tiles 21 is done in the same way as described above.

[0037] In principle, it is possible to design a module with similar components in order to meet these market requirements. FIG. 8 shows the rear view of such a module 51 with the existing LED board 41, which in this case, however, has two connectors 44. This enables electrical "daisy chaining," i.e., a direct cable connection from module to module without branches or distributors. The modules of a device are connected to a cable harness in a line or bus line. Of course, just one connector would also be possible, from which a cable leads from each module to a common distribution box, which also houses the power supplies and control electronics.

[0038] The module 51 is provided on the rear with a cover 53, which has cooling fins 54 and connector openings 55 for access to the connectors 44. Furthermore, fastening ribs 56, each with a transverse bore 57, are shown. On the support frame (not shown), there are adapters with seals for the cover 53, which serve as passages for the connecting cables. The module 51 is inserted into these adapters and secured from behind via the transverse bores 67 with adjusting screws. Its position can also be adjusted within its range of movement. This illustration and description is merely exemplary; countless fastening options and locking connector systems are known; they are not part of this application.

[0039] In this case, the front view is a frameless array of 4x2 tiles 21 with adhesive 32 applied all around and spread around the outside. The carrier plate 1 is only the size of the LED board 41 and is folded over on all sides to form a stiffening frame 52, welded or glued at the corners, into which the cover 53 is inserted with a precise fit. However, the frame can also be attached as a separate bent part with weld points all the way around the flat carrier plate 1 inserted therein. The LED board 41 is aligned with the optics 24 via its fitting holes 45 and the positioning pins 23 and is held elastically on the optics 24 by means of spring bridges 47, which are attached to the positioning pins 23. Frame 52 and cover 53 are sealed to each other at the end of frame 52 with adhesive 32; a circumferential adhesive tape can also be glued around as a protective cover.This module differs from competitor models in that it contains a Faraday cage.

[0040] FIG. 9shows a cross-section through such a module 51. Here, the poorer operating conditions are immediately apparent: ventilation openings are not possible due to the required tightness, which is why the spring bridges 47 sitting on the positioning pins 23 must be used. The interior does not allow convection and is reminiscent of a particularly poorly conductive triple-pane insulating glass unit; the heat can only be dissipated through external convection, which may of course still be sufficient for some applications or colder regions. Alternatively, internal forced convection could be implemented, for example via compressed air hose connections. The electrical connection and control of the modules can, however, be designed identically to a version in a common housing and thus use not only identical tiles 21, but also identical LED boards 41 and spring bridges 47, thus very efficiently covering both display systems described above.

[0041] Many details are presented in an advantageous form, but only as examples; numerous alternative designs are possible which do not violate the formulated claims.

Claims

1. Display surface, in particular for graphic variable message signs of any size, for displaying programmable content by means of full-colour LED optics arranged in a pixel grid, as a stable front of a mostly metallic, sealed housing accessible through rear doors or hinged, in particular taking into account all mechanical, lighting and environmental specifications according to standard EN 12966, characterized in thatthe display surface of the housing comprises a metallic flat carrier plate (1) which is stiffened by longitudinal and transverse struts (5, 6) and firmly connected to the housing and has an opening (2) for each optic (24) as well as fitting holes (4) for positioning pins (23), that this carrier plate (1) is formed by preferably rectangular or square tiles (21) made of plastic, in which the optics (24) are tightly inserted in a grid arrangement, which also have positioning pins (23) and a peripheral edge (30) with a support surface (31) as an adhesive surface, along which they are glued precisely and tightly to the carrier plate (1), wherein the optics (24) protrude inwards through the openings (2) of the carrier plate (1), and that from the inside between the longitudinal and transverse struts (5, 6) fitting LED boards (41) are positioned precisely on the projecting positioning pins (23) and their fitting holes (45) the optics (24) are aligned,into which they radiate their light and are pressed against the optics (24) under defined pre-tension by means of spring bridges (46, 47) which are locked between the longitudinal or transverse struts (5, 6) or fastened to the positioning pins (23).

2. Display surface according to claim 1, characterized in that the tiles (21) completely cover the size of an LED board (41) either individually or in a grid arrangement of several tiles, and the LED boards (41) completely cover the size of the display area either individually or in a grid arrangement of several LED boards.

3. Display surface according to claim 1 or 2, characterized in thatthe tiles (21) are made of black, temperature- and weather-resistant plastic, in particular polycarbonate (PC), and the optics (24) are made of highly transparent, temperature- and weather-resistant plastic, in particular Plexiglas (PMMA), and the insertion of the optics (24) into the tiles (21) is carried out by pressing and / or gluing, or preheating the tiles (21) and / or cooling the optics (24) and pressing in as a shrink press fit.

4. Display surface according to claim 1, 2 or 3, characterized in thatthe tiles (21) have roof prisms, knobs, microprisms or micro-holes (28) on their front side, which direct sunlight into irrelevant areas, or distribute and absorb it by multiple scattering and have a protective tube (29) formed on their back side around each optic (24), which protects the optic during assembly from damage, contamination and displaced adhesive, acts as a further centering for the individual LEDs (42), but also prevents the LED light as well as penetrating sunlight from one optic (24) to the adjacent optics.

5. Display surface according to at least one of claims 1 to 4, characterized in thatthe LED board (41) has the LEDs (42) in a grid arrangement on its front side and at least one plug (44) and functional components (43) on the back side, keeping the pressure positions of the springs (48) and fitting holes (45) for the positioning pins (23) free, and its outline is slightly smaller than the distances between the longitudinal and transverse struts (5, 6).

6. Display surface according to at least one of claims 1 to 5, characterized in that the spring bridges (46, 47) which are locked into the longitudinal struts (5) or fastened to the centering pins (23) are made of fiber-reinforced PC, polyester or spring-formed metal and have a stable body which has elastic springs (48) which are evenly distributed at several points and which press the LED boards (41) against the optics (24).

7. Display surface according to at least one of claims 1 to 6, characterized in thatthe carrier plate (1) has openings (2) for the optics (24) in the pixel grid, as well as positioning holes (3) for the longitudinal struts (5) arranged regularly in the grid spacing of the LED boards (41) and fitting holes (4) for their positioning pins (23) in the grid spacing of the tiles (21), and the stiffening longitudinal struts (5) engage in their positioning holes (3) with matching extensions (5a).

8. Display surface according to at least one of claims 1 to 6, characterized in that the carrier plate (1) is formed by arranging carrier profiles (11) perforated in the optical grid in the grid width of the LED boards (41) in a row, whereby their legs act as stiffening longitudinal struts and the edges (12) form a continuous web to support the adhesive (32) later lying above it.

9. Display surface according to at least one of claims 1 to 8, characterized in thatIn the grid spacing of the LED boards (41), cross struts (6) are inserted in slight overlap with the longitudinal struts (5) by means of alternating recesses (5b, 6a) for precise positioning.

10. Display surface according to at least one of claims 1 to 9, characterized in that the inserted longitudinal struts (5) or the legs of the support profiles (11) have large ventilation holes (8) close to the support plate (1) and the cross struts (6) have a large distance from the support plate (1) due to the slight overlap with the longitudinal struts (5) in order to achieve good air circulation along the support plate (1) and the LED boards (41) both during horizontal and vertical installation.

11. Display surface according to at least one of claims 1 to 10, characterized in thatthe support plate (1), support profiles (11), longitudinal and transverse struts (5, 6) and the housing are made of aluminum, or in the case of aggressive environments of stainless steel, whereby only the housing is painted or powder-coated and the support plate (1) and support profiles (11) including stiffeners are bare.

12. Display surface according to at least one of claims 1 to 11, characterized in that the cohesion of all metallic components of the display surface, including their fixing in the housing and the necessary joining of the support plates (1) or the longitudinal and transverse struts (5, 6), is achieved by low-distortion placement of sufficient welding points (10) and / or by means of laser welding, wherein the housing can advantageously already be powder-coated or painted and its welding positions were preferably covered or ground bright after coating.

13. Display surface according to at least one of claims 1 to 12, characterized in thatFor mounting the tiles (21), a black, weatherproof, permanently elastic, and highly viscous adhesive (32), preferably based on polyurethane or polymer, is introduced in the form of an adhesive bead into the grooves of the connection sides for the tile (21) to be inserted, preferably by hand, or the adhesive (32) is applied circumferentially, with the aid of automation, directly onto the contact surface (31) along the edge (30) of the tile (21) before insertion.

14. Display surface according to at least one of claims 1 to 13, characterized in that the positioning holes (3) for the longitudinal struts (5) and the connecting groove of the support plate (1) to the housing profile (9), as well as in particular the piece joints of the support plates (1) or support profiles (11) in the case of large devices, lie exactly under the adhesive beads of the tiles (21) and are sealed by them.

15. Display surface according to at least one of claims 1 to 14, characterized in thatit is only the size of an LED board (41), the carrier plate (1) has a frame (52) and is fully equipped with tiles (21), the LED board (41) is pressed on with spring bridges (47) fastened to the positioning pins (23) and is covered from behind by a cover (53) with cooling fins (54) and is fixed and sealed all around with adhesive (32), which also has watertight, adjustable and lockable plug connections (55), which preferably also serve as fastenings and thus forms an exchangeable module (51) for modular displays of any size on a suitable carrier frame with cabling prepared for this purpose.

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