NL8120461A - DOUBLE GRILLE FOR GAS DISCHARGE LAMPS. - Google Patents

Description

,. 1 ,, 81 20 4 6 1 D HO / Se / Willumsen-1 "Double grille for gas discharge lamps."

The invention relates to a grid for gas discharge or fluorescent lamps, preferably for ceiling or wall lighting, comprising a number of cells, which are bounded by walls of an appropriate height and which are located at regular distances such that light can pass through the cells. fall.

Such a grid is known from the Danish patent application 3542/76, which describes a low lighting grid, which comprises two grid plates, which lie on top of each other and which have different heights. Both grid plates are formed as low lighting grids, i.e.

mirrored grids, all walls or strips having curved surfaces. The curvature of these curved surfaces is directed away from the light source such that 115 has the largest opening directed towards the illuminated object, after which the light sent through the curved specular walls is emitted as a beam of rays. The grid plates are placed directly on top of each other in that a part of one plate engages in grooves in the other plate. This known .20 grating requires a relatively large amount of material for production and, moreover, a mold for the manufacture of each grating, thereby increasing production costs. The grid manufactured in this way is relatively heavy.

French Patent 933350 discloses a grid comprising substantially triangular walls, one top angle being directed away from the light source and the walls woven together like in a screen. However, this schedule is difficult to make.

Furthermore, different types of low illumination or shielding grids are known, which are made of a single grating plate comprising, for example, perpendicular walls, which adjoin the individual light passages.

These gratings also require a relatively large amount of material for production, making these gratings unnecessarily heavy.

In particular, the manufacture of low lighting grids often has longitudinal damage up to. due to stresses in the material that occur during the curing of the material during injection molding. A high percentage of grids therefore becomes unsuitable shortly after production, and many complaints occur in practice since the grids sometimes warp as they age. Another factor which makes the manufacture of low illumination grids expensive is that they must be coated with a mirror layer, which coating must previously be applied over the entire height. Due to the high height of the grids, this metal coating can be difficult to apply as it becomes more and more difficult to penetrate the metal coating over the entire surface into the modules as these modules become higher. This is due to the fact that the metal outflow can only penetrate with difficulty from the large opening to the bottom near the small opening, while practically no material transfer takes place through the small opening during the rotation of the gratings in the metalizing- The device, when the small opening is opposite the source of the metal radiation.

It is the object of the invention to provide a discharge lamp grating wherein the manufacture of such grids requires lower material consumption, while retaining the usual desired shielding angle of the different grids, so that the whole grating is lighter and new light effect is obtained.

The invention also provides a low ventilation grid, the production costs of which can be significantly reduced by reducing the failure rate, which is the result of disturbing stresses which occur during the injection molding hardening and moreover by limiting the consumption of primary and coating varnish, as well as the other costs associated with vacuum metallization.

This object is achieved with the described grating comprising at least two independent, equally high, grating elements arranged parallel to each other, i.e. an upper grating and a lower grating, of which at least one grating element, preferably the upper one, is a protective grating, which grids are attached to each other near to each other or at predetermined distances from each other by means of holding means and wherein the cells are at least one of the grating elements is rectangular, polygonal or cylindrical. By a screening grid, which is also referred to as a light diffusing grid, is meant a grid comprising a straight or curved, non-mirroring wall which emits diffuse light in the room.

The above-described manufacture of the individual grating elements allows for a significant increase in the wall space viewed in the direction of the grating surfaces, without the wall height of each grating element necessarily being more than half the height of a conventional grating of a corresponding type, under maintaining the usual shielding angle. In such production, the individual walls can be made thinner simultaneously without reducing the strength of the final grid. As a result, significant overall material savings are obtained compared to the production of. known grids. Furthermore, new light effects are possible by placing the grating elements at a mutual distance, which varies from 0 mm to, for example, the height of more than one grating element. Since the grate comprises a lower and an upper grate, both of which have a small height, thinner walls are obtained which give rise to a faster injection molding method.

According to the invention, the grating elements 3 can be spaced apart by means of columns, whereby a surprising new light effect is obtained, or the grating elements can be welded together by means of elongated protrusions on each other 8 1 2 0 4 6 1 -4 - lying edge surfaces. In the latter case, a sandwich construction is obtained, which has the strength of that of laminated parts.

With only two grille elements and with the top grate element designed as a screen grille comprising walls in particular tapering walls and with the narrow top edge directed towards the light source and optionally with curved wall surfaces and with the lower grate element with the same geometric shape as the top grille element '10 but with the narrow bottom edge facing away from the light source, it is achieved that the grating elements are manufactured in the same mold, so that, in addition to material savings, production is cheaper. In addition, since the mold is not as deep and wide as in the production of a known grid for the same overall grid height, faster production is ensured.

When it is desired to manufacture a grid in which the grid elements are spaced, a solid fastening is obtained according to the invention in that the bottom and top of the columns are fixed to the grid elements in the upper and lower intersecting parts of the teeth and preferably in the recesses formed on said cutting parts.

According to the invention, each grating element can be integrally formed with a half column, which is half height as the predetermined distance and the free end surfaces of the half columns are attached to each other. In this way, the grating elements can be easily made in the same mold provided that they have the same geometric shape.

It is preferred according to the invention that the grating elements have the same shape, wherein all grating elements used may have either flat or curved wall surfaces, the curvature of which is directed away from the light source. As a result, grids with new lighting effects are obtained. According to a simple embodiment, all grating elements, which form an 8120461 -5 part of the grating, comprise flat parts, since the simplest embodiment, which is the easiest and cheapest to manufacture, according to the invention, comprises only two identically shaped grating elements.

According to the invention, the grating elements can be of different types and at least one grating element, preferably the grating element facing away from the light source, can comprise substantially wedge-shaped walls provided with wedge-shaped and curved parts, the curvature going downwards. is oriented, while the other grid element or elements may comprise flat wall surfaces. As a result, a light, material-saving grid is obtained, which allows special light effects. The fact that the top grating is transparent ensures that the grating functions to a large extent as a light-catching means by the transmission of light through the walls of the top grating element.

According to the invention, at least one grating element is colored with a color different from white or clear transparent, which shade is obtained by either an outer coating on the walls or by the desired transparent plastic material which is painted . The use of clear, transparent paint material or by reflecting the body color of the top grating element provides an increase in light transmission, with the transmitted or reflected light being partially reflected by the lower grating element to achieve different shades of color.

By metalizing at least one grating element, preferably the element facing away from the light source with a reflective layer, preferably the lower grating, which is then made reflective, while the upper grating has a non-reflecting layer. obtained a grating which has the effect lying between a low illumination grating and a shielding grating. In this way, pleasantly muted room lighting is obtained, while objects located under the light source are more strongly illuminated.

8120461 -6-

By attaching the top shield grille to the bottom low vent grille, the stresses formed in the bottom grille are compensated by the top shield grille. Since only the low 5 ventilation grid has to be metallized to mirror and thanks to the lower height compared to other low lighting grids, significant amounts of primary and topcoats are saved before and after metallization, while further the cost of vacuum metallizing while the metallization can be performed in a shorter time due to the lower height.

The embodiment of the top grating element according to claim 12 provides the best possible compensation for the damage that may occur during production since the top grating has a slight tendency to curve in the opposite direction. In addition, this embodiment ensures that the largest possible opening is directed towards the light source.

The apex angle and the plugs mentioned in the characterizing part of claim 13, in a simple manner, ensure that the grids are correctly positioned relative to each other in connection with the mutual attachment.

25 Although the grids can be glued together, which does, however, cause environmental problems, it is

V

according to the invention it is better that the individual parts are joined by ultrasonic welding techniques. When the opposing edge surfaces of the grating members have elongated protrusions, they protrude from protrusions during welding to form a rigid system. to gain. In this way, the use of glue, which would have a price-increasing effect, can be avoided, which glue is moreover often in conflict with the provisions of environmental laws.

When certain fireproof materials are used, the projections of the grids must be coupled without the use of adhesives. To meet this requirement, an embodiment of the invention may be provided 8120461-7, wherein the individual grid elements are assembled in a simple manner. The grating elements according to this embodiment optionally comprise intermediate columns, which are attached to each other by protrusions on the 5 different parts, which protrusions are pressed closely into corresponding recesses in corresponding parts.

The projection recesses can additionally be formed to obtain a snap connection, to ensure reliable coupling of the parts.

When each grating element is manufactured by means of a number of rectangular grating elements with a selected number of cells (light passages), these elements can be formed into a grating by mutual fixing, in which case according to the invention it is preferred that the grating elements of a lower grating are offset from the elements of an upper grating, thereby preventing warping or deformation of the grids into an arc upon assembly, such that a low failure rate is obtained.

The invention is elucidated on the basis of embodiments according to the drawings, in the drawings: Fig. 1 shows a side cross-sectional view of a grid according to the invention,

Fig. 2 is a cross-sectional view along line A-A

from fig. 1,

Fig. 3 is an axioroetric illustration of the part C of Fig. 2,

Fig. 4 is a cross-sectional view through a second embodiment of the grating according to the invention corresponding to the view from Fig. 1,

Fig. 5 shows a schematic top view of a grid 35 with hexagonal cells,

Fig. 6 is a sectional view of the second embodiment of a grid according to the invention corresponding to the view of Fig. 1, 8 1 2 0 4 6 t -8-

Figures 7 and 8 are cross-sectional views corresponding to Figures 1 and 2, respectively, of a known screening grid,

Fig. 9 is a cross-sectional view of a third embodiment of a grid according to the invention,

Fig. 10 a grating element for use with the grating according to Fig. 9, viewed from the wide edge surface of the grating element,

Fig. 11 is an enlarged cross-sectional, partial view through a low lighting grid according to the invention along the line D-D from Fig. 12,

Fig. 12 shows on a different scale a top view of a lower grating for a low lighting grating of Fig. 11, and

Fig. 13 a sectional view along the line E-E

from fig. 2.

Fig. 1-3 shows an embodiment of the light grid according to the invention. The grid comprises two basically equal grid elements 1,2, light passages or 20 cells 3, which are bounded by walls 4,5 and 4, respectively. 6,7 which are perpendicular to each other and comprise flat wall surfaces such that each grating element forms a screening grating. The grid elements are mutually spaced by means of holding means in the form of columns 8, which are preferably located on all cutting parts. These columns 8 can be cast in one piece with a grating member and comprise a protrusion (not shown) at your opposite ends, which engages a recess (not shown) in the intersecting part of the other grating element 30. A light source 9 is above the grid of fig. 1 is shown in broken lines The grids are coupled by an intermeshing or ultrasonic welding of the columns at the contact points of the grid concerned.

However, glue can also be used, but this can cause environmental problems. Alternatively, snap means can be used, but this increases the price of the production mold.

8120461 -9-

According to an embodiment, the two grids are made identical with a half column on each grating. These half columns comprise flat wall surfaces and are attached to each other along the line AA of fig. 1, said protrusions and recesses not being absolutely necessary for the manufacture of the grating, although they allow the precise positioning of the grating elements relative to from each other. This positioning can be assisted by other mechanical means, but without a permanent coupling between the grid elements.

It is advantageous to use spacers in the form of vertical columns 8. The bottom 10 and the top 11 of these columns are attached to the walls 6,7 of 15 the top edge surface 12 of the bottom grate element or the bottom grate 1 and to the bottom edge surface 13 of the walls 4,5 of the top grid element or the top grid 2. The bottom and top of the columns are also attached to the grids in the top and bottom intersecting portions 14 of the walls 4,5,6,7.

Another embodiment of the grid according to the invention is shown in fig. 4. The upper grating 2 of this embodiment corresponds to that of FIG. 1, while the surface of the walls 16, 17 of the lower grating 15 are nearly tapered and curved as shown and, moreover, reflective. For example, the curvature can be parabolic or, as shown, part of a circular arc with a radius R. As shown in Fig. 4, it is advisable because of the illumination that the

v A

lower edges 18 of the walls are rounded. The grid elements 2,15 of this grid are also spaced apart by means of the columns 8, as described above.

Fig. 5 schematically shows that it is not necessary for the walls to be perpendicular to each other, but the walls 14 of this embodiment are formed in such a way that hexagonal cells or light passages are created. The columns 8 of this embodiment are preferably placed in the cutting parts 21 of the three walls 19. There are also other embodiments of the grid according to the invention. For example, each grating element may comprise a grating element having perpendicular walls with a cylindrical light passage placed in each light passage or cell. Each of these embodiments of the grating elements provide the particular light effect or shows a characteristic image when illuminated, These embodiments have not been discussed in further detail.

Fig. 6 shows an additional embodiment of the invention, in which an intermediate grid 22 is placed between and coupled to the bottom grid element 1 and the top grid element 2. This intermediate grid is spaced from the other two grids by means of the columns 8 , 23. A grille of this type manufactured as a screen grille with a flat wall surface provides additional material savings when manufacturing the grille. Such a grid, however, requires slightly stronger discharge lamps than the grid according to Figures 1-3.

The preferred embodiment is drawn in Figures 9 and 10 and includes two equal grid elements 15,15 ', the wall surfaces 16,17 of which are tapered and curved, and which surfaces are welded together stiffly, the wide edge surfaces 24 of which the walls are against each other. The retaining means are in the form of elongated protrusions 25 which extend in the center of the edge surface 24. The height of these protrusions is between 0.1 and 0.4 mm and preferably at 0.2 mm. In the ultrasonic welding these protrusions are flattened in such a way that a tight, reliable connection between the grating elements 15,15 'is obtained.

Due to the thin design of these walls, such a grating has a large light incidence opening compared to known grids, so that a large transmission of light compared to the known technique is obtained.

8 1 2 0 4 e t "-11-

An additional embodiment of a low ventilation grid according to the invention is shown in Figures 11-12. This low illumination grille comprises a lower grille 31 and an upper grille 32 and, as shown, is located under a light source 33, which is indicated by a broken line and usually consists of one or more gas discharge tubes.

The lower grid 31 includes a first and a second pair of walls 34,35 that are perpendicular to each other.

These walls 34,35 form light passages of a desired width, for instance about 12 x 12 mm. However, many other dimensions of the openings are also conceivable, e.g. 200 x 200 mm. The height of the walls depends on the determined width and with a width of 12 x 12 mm, the height is correspondingly about 6 to 10 mm and can for instance amount to 6.5 mm from the top surface. On the bottom, the walls 34,35 are rounded, which gives a better paint distribution during metallization. Moreover, the tendency for droplets to form is not as great as with sharp edges, thus avoiding the risk of browning and the lacquer breaking off. The walls 34, 35 comprise curved surfaces 37 with a radius r, which is determined by the lighting requirements. The wall surfaces can also be parabolic in cross section.

In the center of the intersecting parts 38 of the walls 34,35, a dowel 39 extending to the light source is arranged. In the present embodiment, this dowel includes either a circumferentially beaded projection 48 or several beaded projections 30 extending circumferentially. According to another embodiment, these dowels can be made without protrusions, see for example the following description of assembling the low illumination grid according to the invention.

The top surface 40 of the walls of the lower grating has a predetermined width b, which in response to the chosen grating height and width of 8120461 # -12- the light opening can have the range of 1.5 to 12 mm and preferably 3 to 4 mm, for example 3.4 mm.

The top grille 32 also includes a first and second pair of parallel walls 41, 42 which are perpendicular to each other and include flat wall surfaces 43.

The height of the walls of the top grid depends on the walls of the bottom grid. The light aperture formed by the walls 41, 42 is in principle the same size as the light aperture formed by the walls 34, 35 of the lower grating, since the lower surface 44 of the walls 41, 42 of the upper grating may have the same width b as the top surface 40 of the walls 34,35 of the lower grating. As shown, the walls of the top 15 grid may be tapered. An opening 45 is formed in the lower surface 44 of the two walls 41, 42 of the upper grating in the cut parts not shown. The shape of this opening 45 is identical to the shape of the dowel 39, which means that the opening may comprise a circumferential recess 46 or recesses extending partly along the circumference, while the opening may also comprise flat walls.

While the lower grating 21 is metalized prior to assembly so that all surfaces 25 thereof are coated with a mirror coating, an upper grating 32 is made of transparent plastic ensuring the greatest possible light transmission throughout the grating.

After metalizing the lower grating 31, 30, the upper grating 32 is pressed over the lower grating such that the bottom surface 44 of the upper grating is in contact with the top surface 40 of the lower grating. As a result, the dowels 39 come into contact with the wall surfaces of the openings 45 When the dowels are provided with circumferential protrusions 48, a snap connection is provided in the corresponding recesses 46. When the dowels 39 and the openings 45 have smooth wall surfaces, the contact surfaces are welded by ultrasonic welding. The top surface 40 and the bottom surface 44 can also be welded together to achieve close contact. In this way the grids reinforce each other and due to the complementary shape they counteract the formation of possible disturbances in the final grid.

The dowels and openings can also be omitted.

The purpose of the upper grating in the above-described embodiment of the low aeration grating of the invention is to collect the light from the light source prior to its further transmission through the lower grating. The collection of light is improved by the injection-molding of the upper grating in transparent plastic, while the lower grating further transmits the light in the known manner to obtain controlled directional illumination.

As mentioned above, the height of a low ventilation grid is often a problem when the metallization takes place in vacuum. This is due to the fact that it can be difficult to introduce the metal layer sufficiently into the modules the higher the modules are, since the metal emanation is difficult to transfer from the large opening to the bottom at the narrow opening, while virtually no metal transfer through the narrow opening. According to the invention, only the bottom grating is metalized, the height being considerably reduced. It is even possible to additionally metallize two opposing lower gratings, whereby a double amount of vacuum-metallized light gratings can be made and consequently processing is limited to almost half the cost compared to known gratings. When assembled the bottom and top grids, they may be offset from each other to obtain a stronger light grille in the manufacture of larger grids, especially since the grating elements and the lower grating and the upper grid preferably takes place by means of ultrasonic welding. In this way the use of glue is avoided, which is an advantage since many of these types of glue conflict with the regulations regarding the protection of the environment. For the manufacture of grids of fireproof material, there is an additional requirement that the top 10 and the bottom grate can be coupled by means of a snap connection.

In all of the above-described embodiments, at least one grating element can be given a color different from white or a clear transparent color. This coloring is achieved either by applying an outer layer to the wall or by painting the additional transparent plastic material itself. One of the rocster elements, preferably the bottom grating element, can be metalized accordingly with a reflective layer, whereby a combination of an appropriate paint on the top grating and a second paint or mirror coating the bottom grating creates different new and surprising produces light effects.

It is preferable to manufacture each grid element from a number of rectangular elements, parts of which are indicated in Fig. 10 et seq. 12. Each element has a predetermined number of cells, e.g. 16 or 64. When coupling, these elements are joined together along the outer surfaces 47 to form a given grating element.

Smaller and therefore cheaper molds can be used in this processing. When assembling such non-drawn elements, it is preferable that the elements of a lower grating are displaced relative to the elements of the upper grating such that an element of the upper grating accurately half of the two elements of the bottom grille overlaps. Elements of the upper grating with 8120461 -15- half the width of a complete element can then be attached to the end of the grating. In this way, the change which tends to occur in cast grids due to the stresses created in the grids during cooling after casting is counteracted. The fixing can be done by glue, but it is preferable to couple them by ultrasonic welding. The changes are counteracted by grids, which tend to bend in opposite directions on top of each other. As a result, tool expenditures and failure rates are reduced and the whole operation is cheaper.

For comparison, Figures 7 and 8 show known low illumination grids. Since this grating has a fundamentally higher wall height than any grating element, its walls are made with a greater thickness than the wall thickness of the grids according to the invention. The walls must be placed closer together in order to obtain the desired screening angle than with the grids according to the invention (see fig. 1, 6 and 7). This implies that a principally larger amount of material is used for the known grid than for the grid according to the invention, as a result of which the production becomes unnecessarily expensive. The known grid also has a greater weight than that according to the invention.

Although the bottom and top grids of the drawings are drawn as rectangular or hexagonal cells, other geometric cell shapes,. e.g. other polygons or circular or oval cells are used.

The advantages of the grid according to the invention can be summarized as follows: - Material savings are obtained since the walls of the grid elements, which are preferably made of plastic, can be considerably thinner than plastic corrugated walls without the to weaken grids and since a number of cells can be omitted, 8 1 2 0 4 6 1 -16-> while maintaining the same shielding angle <0 ^, each cell or light passage can be relatively larger.

- A lower height of both the upper and the lower grating, which allows less expenditure on tools 5 and a faster injection molding method.

A slight difference exists in the thickness of the material over the entire height of the walls, as a result of which a smaller degree of change in the longitudinal direction of the grid occurs.

Production is simpler since the working tools can be made easier due to the lower height of the grating elements.

- A combination grating in which the bottom grating element is formed with curved surfaces to obtain a low-illumination grating is cheaper to make since only the lower grating element needs to be specular, thereby saving large costs with regard to the specular rendering, which can furthermore be done more efficiently. due to the lower grid height.

New light effects can be obtained by means of the space between the grids and by varying the combination of shielding grids and low illumination grids and coloring each grating element.

25 - A larger light transmission is obtained due to the larger cells and the smaller wall thickness.

The top and bottom grating elements can be arranged offset to each other so that a strong light grating is obtained when larger light grids are made.

- The total weight is lower.

- When creating a low lighting grid, the consumption of paint for the primary and the paint of the element after metallization is reduced.

35 - When making a low illumination grid, the costs associated with vacuum metallization are considerably reduced.

8120461 -17- - The joining of the lower grating and the upper grating and the assembly can be done by ultrasonic welding, gluing avoiding environmental problems. The ultrasonic welding takes place faster and is cheaper.

- A light grid with a small energy consumption compared to the amount of light that is transmitted.

- A light grille that allows for various decorative designs.

Outside of the above embodiments, various variations can be made within the scope of the invention. For example, a bottom grating of the shape shown in FIG. 5 can be made parabolic or provided with a circular wall surface or as a multilayer grating. The lower grating element 1 of the grating according to fig. 6 and / or the intermediate grating 17 and / or the upper grating element 2 can moreover be made as a low lighting grating with curved wall surfaces. Each version provides a new light effect.

The bottom surface of the top grille may be narrower or wider than the surface of the bottom grate. It is therefore clear that the connection by means of protrusions and recess can be replaced by other coupling means, such as, for example, tongue and groove.

8120461

Claims (17)

1. A discharge lamp grid, preferably for ceiling or wall lighting, comprising a number of cells bounded by walls of an appropriate height and located at regular distances such that light can pass through the cells, characterized in that the grid is at least two independent, equally high, planar, mutually parallel grating elements (1,2,15,15 ', 22,31,32), an upper grating and a lower grating of which at least one grating element, preferably the upper grating ( 2,32) is a screening grid, which grids are mounted near or at predetermined distances from each other by means of holding means (8,25,29,45) and wherein the cells in at least one of the grating elements are rectangular, polygonal 15 or cylindrical. Grate according to claim 1, characterized in that the holding means are elongated protrusions (25) or vertical columns (8), the bottom (10) and the top (11) of which are permanently connected to the top edge surface. (12) of the walls (6,7,16,17,19) of the lower grating (1,15,22) and with the lower edge surface (.13) of the walls (4,5,15,17) of the top grid (2.15 ', 17). Grid according to claim 2, characterized in that the protrusions (25) are formed as short elongated protrusions on the edge surface (24). Grate according to claim 2 or 3, characterized by only two grate elements (15,15 ') and in that the top grate (15') is a screen grille with walls (16,17), in particular tapered wall surfaces, with the narrow top facing the light source (9) and optionally curved wall surfaces, while the bottom grating (15) has the same geometric shape as the top grating (15 '), but with the narrow bottom edge facing away from the light source (9). 8120461 4 -19- Grate according to claim 2, characterized in that the bottom (10) and the top (11) of the columns (8) are attached to the grate elements in the upper and lower cutting parts (14,15) of the walls. (4,5,6,5,16,17) and preferably in the recesses formed in the cutting parts. Grating according to claim 2, characterized in that each grating element (1,2,5) is integrally formed with a half column, which is half height as the predetermined distance and in that the free end surfaces of the half columns are attached to each other. Grate according to claim 1, and one or more of claims 5 or 6, characterized in that the walls (4,5,6 7) 16,17,19) are the same in all grate elements (1,2,7). cross section and in case the wall surfaces are tapered and optionally comprise curved wall surfaces, with the wide part facing the light source (9). Grate according to claim 1 and one or more of claims 2,5,6, characterized in that the grate elements (2,15) have different shapes and that at least one grate element (15), preferably the grate facing away from the light source (9), comprise walls (16, 17) which are substantially wedge-shaped in cross-section and with curved wall surfaces, which curvature is directed downwards, while the other grating element has flat wall surfaces. Grid according to one or more of the preceding claims, characterized in that the top grate (15, * 30 15 ', 32) is made of opal or transparent plastic. Grate according to one or more of the preceding claims, characterized in that at least one grate element is colored with a color that differs from white or transparent, which color is applied either by means of an outer covering layer on the walls or in that the additional transparent plastic material is colored. 3 1 2 0 4 6 1 -20- ψ <* Grate according to one or more of the preceding claims, characterized in that at least one grate element is metallized with a reflective layer, preferably only the bottom grate, while the top grate has a non-reflective layer. The grating of claims 1 and 10 and 11, and wherein each bottom and top grating comprises a first and a second pair of parallel walls located directly above and perpendicular to each other, said walls forming light passages of a desired height and width and wherein the walls of the lower grating are wedge-shaped, the pointed end of the wedge pointing downwards and comprising a substantially flat top surface and preferably a curved mirrored wall, characterized in that the walls 15 (41, 42) of the top grating (32) are formed as a shielding grating with parallel flat walls or wedge-shaped with flat wall surfaces widest at the bottom surface (44) facing away from the light source (33), which bottom surface is preferably the same width (b) has as the top surface (40) of the walls (34, 35) of the bottom grids. Low illumination grid according to claim 1, 10, 11 or 12, characterized in that openings (45) are formed in the intersecting parts of the two series of walls of the upper grid (32) in the bottom surface (44) of the upper grille (32) engaging apertures corresponding to dowels (39) formed integrally with the walls of the lower grille (31) in the cutting portions (38) of the walls (34,35). 30s Low illumination grid according to claim 12, characterized in that the dowels comprise peripheral projections (48), which correspond to recesses (46) in the openings. (45) intervene. Grating according to claim 1 and one or more of claims 2-13, characterized in that the individual parts (1,2,8,15,15 ', 23,25) are coupled by ultrasonic welding. 8120461% -21- Grating according to claim 1 and one or more of claims 2-10, characterized in that the grating elements (1,2,15,15 ') additionally comprise intermediate individual columns (8) which are joined by protruding 5 seis thereon and are closely fitted into corresponding recesses in separate parts. Grid as claimed in claim 1 and one or more of the claims 2-12, wherein each grating element is made by means of a number of rectangular grating elements 10 with a selected number of cells, which elements are joined together by means of a grating, characterized in that that the grating elements of a bottom grating (1,15,22) are offset from the grating elements of an upper grating (2,15 ', 17). 8 1 2 0 4 e i