EP2404289A1

EP2404289A1 - Lighting device having a main body made of transparent material

Info

Publication number: EP2404289A1
Application number: EP11715700A
Authority: EP
Inventors: Marcus Menden
Original assignee: Menden Marcus
Current assignee: Menden Marcus
Priority date: 2010-04-28
Filing date: 2011-04-18
Publication date: 2012-01-11
Anticipated expiration: 2031-04-18
Also published as: DE212011100018U8; WO2011134830A1; US20120092866A1; DE212011100018U1; US8733973B2; EP2404289B1

Abstract

The invention relates to a lighting device having a main body (3) made of transparent material, in which a plurality of light-emitting diodes (12) are disposed on a flexible adhesive strip (13) having integrated conductors. The aim of the invention is to provide an easily produced, compact lighting device having outstanding lighting properties. Said aim is achieved in that a hollow chamber (24) open on one side is milled into the rear face of the main body (1-4), the length and width thereof being slightly smaller than the width and length of the main body (1-4), so that at least one closed edge lip arises along the periphery of the main body (1-4), the adhesive strip (13) having light-emitting diodes (12) is applied over the entire length of the edge lip (5-11) on the inner face thereof such that light-emitting diodes (12) are disposed on the inner faces of edge lip segments opposite each other. The light-emitting diodes (12) on the side edge lip (5-11) illuminate the solid segment (19) of the main body (1-4) in front of the hollow chamber (14) and generate a high light density on the front face. The rear face of the hollow chamber (24) is closed by a cover (15-18).

Description

LIGHTING DEVICE WITH A GREEN BODY OFF

TRANSLUCENT MATERIAL

description

The invention relates to a lighting device according to the features of the preamble of patent claim 1 and a method for producing such a lighting device.

In such lighting devices, the body has the shape of a letter or other symbol or logo to be displayed in a luminous manner.

Such lighting devices are known for example from the document WO03 / 075249 A1. The basic body provided, for example, in FIGS. 1 to 9 of this document with the reference numeral 2, consists of an angled metal sheet. It is closed by a light-conducting cover element 3, in particular made of acrylic glass. The light-emitting diodes are glued by means of a two-sided adhesive tape on one of the two parallel sections of the U-shaped sheet metal body near the transverse leg. The distribution of the light over the entire light exit surface of the U-shaped main body is to take place by reflections on the bands formed by the metal sheets. FIG. 8 shows a measure intended to improve the illumination of the entire area. An angle is adhered to the lower surface of the leg between the two mutually parallel portions of the U-shaped main body to allow the reflection of the light beams of the light-emitting diodes on the entire area of the light-transmitting light exit surface. The embodiments in FIGS. 26 and 27 of the drawings alternatively disclose a U-shaped sheet-metal housing open towards the wall as a basic body, which only allows the light to exit towards the wall. Furthermore, a Embodiment disclosed in which both the visible front surface and the wall-side rear surface is used as a light exit surface.

In all cases, the main body must have a considerable height in relation to its width to ensure that the reflection of the

Light rays on the walls of the U-shaped sheet metal housing leads to a complete illumination of the entire light exit surface.

The publication US 2002/01 53257 A1 describes a lighting device with a housing which comprises a bottom and side walls, as well as with a lid. A strip of electrical conductors, on which light-emitting diodes are arranged, is applied to the outer side wall of the housing. Again, it is problematic to achieve a homogeneous illumination of the visible surface. The document DE 299 1 2 986 U 1 describes a character-like highlighter with a light-equipped, light-conducting body made of plastic, in particular in the form of a plate. The photoconductive plate has in its lateral edge region a narrow channel in which light-emitting diodes are arranged. Alternatively, a narrow channel is mounted in the middle of the plate, where back-to-back light emitting diodes are arranged in each case in the outer regions of the plate.

The object of the invention is to provide an easily manufacturable lighting device with excellent lighting properties, the body can be made very compact. Furthermore, the object of the invention to provide a method for producing such a lighting device.

This object is achieved by the totality of the features of claim 1.

In the body of translucent material, in particular acrylic glass, the back side a one-sided open cavity is milled, wherein the Width and length of the cavity is slightly smaller than the width and length of the base body, so that at least one along the periphery of the body extending, closed edge web in the rear region of the body extends, the adhesive strip with the light-emitting diodes over the entire length of the Edge web is applied to the inside, that light-emitting diodes are arranged on the mutually facing inner sides of opposite edge land sections and illuminate the massive photoconductive body in front of the cavity, wherein the cavity is closed by a lid.

There are luminous letters that are made entirely of PMMA, too

Acrylic glass called, exist. Here holes or slots are cut into the acrylic glass body. In these slits or holes elongated LEDs are inserted. Subsequently, the cavity in the Schl itz or the bore is potted with hardening plastic, so that the diode is firmly enclosed in the body of translucent material. The main disadvantage of this embodiment is that in case of failure of a diode, the entire lighting device must be replaced. Removal and replacement of the encapsulated LEDs of the lighting device are not possible.

By contrast, the present invention proposes milling in a cavity on the back side of a base body made of light-permeable material, such as acrylic glass. The contour of the cavity corresponds to the contour of the luminous device (eg the shape of a letter), the width and length of the cavity being slightly smaller than the width and length of the main body. In this way, creates a circumferential closed edge web, preferably with a width of a few millimeters. When the main body surrounds an open section (such as the letter "B" or the number "8"), several circumferential closed edge webs are created when the cavity is attached. The main body can in particular consist of milky transparent material. The acrylic glass may in practice have a light transmission in the range of 40 to 80%. Optimal results were achieved in the range of 60%. The milky cloudy coloring of the acrylic glass causes a diffuse light distribution over the entire cross section of the lighting device. If a bright but spot-like illumination of the front side of the lighting device is desired, the base body can be made transparent and possibly only have a diffusely transparent cover layer.

The edge bar provides an optimal surface for attaching the adhesive strip with the LEDs. There are finished self-adhesive strips with regularly mounted light emitting diodes are known in which the electrical conductors are integrated directly. The light emitting diodes are provided by surface mountable components, so-called SMD

Components, formed. The distance between two consecutive light-emitting diodes, that is, the distance from the center of the LED to the center of the next LED, is usually in the range between 5 mm and 40 mm. By varying the distance, the desired luminance of the lighting device can be set exactly. The tapes supplied as rolls with several meters in length can be cut and contacted at predetermined locations between two light-emitting diodes. For this purpose, a connection cable can be soldered to the conductor tracks in the adhesive strip. The mounting of such light-emitting diodes on the inside of the opposite edges of the cavity of an acrylic glass body is very simple and fast. Furthermore, the adhesive tapes or at least portions of the adhesive tapes can be exchanged if individual light-emitting diodes are damaged. The tapes can be provided with monochrome light emitting diodes that emit light in a specific wavelength. Furthermore, the adhesive tapes can be provided with white light LEDs. White light LEDs usually consist of three individual diodes, which light in deliver different colors. I can therefore also adhesive tapes with RGB LEDs are used in which the single diodes with the colors red, green or blue can be controlled individually and so the color of the light emitted by the light emitting diode can be varied.

A cover whose contour substantially corresponds to the surface of the lighting device or of the base body covers the cavity. At the same time, the cover provides privacy protection so that the user can not look at the interior of the lighting device. The lid also protects the electronic components of the lighting device against contamination or mechanical stress. Close I can be achieved depending on the nature of the lid, that the illuminated letter glows backwards or that no light escapes at its rear.

Since the light emitting diodes radiate from edge bars on both sides of an elongated section of the lighting device into the cavity and are arranged relatively close to one another, the high luminance light distributes uniformly over the entire surface of the lighting device. This is promoted in particular by the fact that the LEDs are arranged on the mutually facing inner sides of opposite sections of the edge web or the edge webs.

The front of the body, that is, the side facing away from the cavity on the back side, may be provided in practice with a translucent cover layer. Especially with colored illuminated letters, but also with white illuminated letters, a cover layer can be used which reflects the desired color very bright. The cover layer may additionally be polished in order to improve the visual impression of the illuminated letter. The cover layer can be easily glued to the remaining portion of the body. The top layer can be made of high quality acrylic glass, so that the production of the remaining body made of simple acrylic glass offers cost advantages.

The peripheral edge web may have a rear translucent portion. This causes light from the LEDs can escape through the edge bar on its back. In conjunction with an opaque lid, z. B. of metal, so creates a thin luminous strip in the region of the edge of the back of the lighting device. In combination with a transparent or diffusely translucent lid, it is possible to ensure that the entire back of the

Illuminated letter is translucent.

If the lid is made of opaque material, its cavity-facing side may have a light color. This leads to a reflection of the light rays impinging on the lid to the opposite side of the cavity, where they enter the base of acrylic glass and illuminate it.

As mentioned, the lid may be made of translucent material to promote the leakage of light to the back. The lighting device in the form of a letter can for example be mounted at a small distance from a wall. Back light causes a corona effect, that is, a ring of light surrounding the letter.

As mentioned, the luminance of the entire visible front side is very high in a massive light-conducting base body illuminated from the side edge web. With the lighting device according to the invention can be at a low height of the body in the order of 35 mm without unacceptably high heat development homogeneous luminance in the order of 1 .000 to 2,000 cd / m ² achieve. The luminance to be achieved can be perfectly controlled by the LED distance.

Should lower luminance be required, the distance of the LED be increased without affecting the uniformity of the illumination. It also does not bother that additional elements, such as a thread for a fastening screw in the plastic material of the body are mounted in the region of the cavity. The cover may be fastened to the base body with a fastening screw which is screwed into a threaded bore in the base body. It can also be provided a plurality of fastening screws to secure the lid to the body. The use of a translucent material such as acrylic glass as

The main body of the lighting device has the disadvantageous characteristic that the heat of the light emitting diodes is transported away relatively poorly. In order to avoid overheating in densely arranged light-emitting diodes or very powerful light-emitting diodes, a heat-conducting layer, preferably a metal layer, can be arranged on the inside of the edge web. On this metal layer of the adhesive strip is glued. The thermally conductive layer causes a distribution of the heat of the LEDs over at least the entire surface of the edge web. From here, the heat can either enter the material of the body or be discharged by convection or radiation into the cavity. The metal layer can be glued down to the support surface of the aluminum cover, so that a heat-dissipating connection between the aluminum lid of the lighting device and the LEDs is formed. The heat is conducted via the adhesive strips carrying the LEDs into the metal layer and through the metal layer into the cover, via the outside of which it is discharged into the ambient air.

The side wall of the lighting device extending from the front side to the rear side can be provided with an opaque coating. As a rule, customers wish to emit light either only through the visible front side of a luminous letter or, if necessary, through the back to generate a Corona effect. The impermeable Coating the side wall prevents unwanted light leakage through this side wall.

It is also possible to provide the visible outside of the outside of the light emitting device with an opaque coating. This gives a luminous letter that emits light only to the rear. This illuminated letter can be made very flat. Due to the fact that the base body and the edge webs are made of light-permeable material, it is possible to produce a backlit lighting device which radiates backwards over its entire rear side or only over the visible area of the edge web, with little effort and high luminance.

With a lit luminous letter, the distance between the back and the front of the illuminated lettering can be between 25 and 40 mm to ensure sufficiently high illumination. In the back-emissive embodiment, where the front is opaque coated, the height of the illuminated letter can be reduced to 20 mm. Nevertheless, a satisfactory light distribution is achieved.

The opaque coating may consist of a light-tight lacquer which is applied in several layers. Preferably, white is first painted in order to achieve the highest possible reflection in the main body of the illuminated letter. Thereafter, a black layer is painted, which has an absolute opacity to prevent light from shining through. Finally, the desired exterior color is applied. In particular, in broad lighting devices, so in letters, numbers or symbols with a large distance between the opposing edge webs can be arranged in the middle of the cavity, a central web of translucent material, in particular acrylic glass, the protrudes from the main body and extends substantially parallel to the edge web. In practice, this center bar can have a diffusely reflecting surface. This central web can be generated when milling the cavity. By milling, it receives a milky-rough surface, which reflects light partially diffuse and partially lets through. The penetrating light component ensures that no darkening of the front side of the lighting device occurs in the region of the central web itself. The diffusely reflected light component increases the illumination of the lighting device in the central region of the cavity and thus acts as a darkening of the

Front facing away from the edge towards the middle. In other words, the surface of the central web lights up brightly due to its diffuse-reflecting properties and forms a second light source whose light rays enter the light source

Penetrate body and penetrate to the front. In this way, it is ensured even with wide lighting devices that forms no dark area in the middle between the edge webs. In practice, the center bar can reach as far as the lid, which covers the cavity.

Finally, the invention relates to a method for producing a

Lighting device with a base body in which a flexible adhesive strip with spaced apart from each other light emitting diodes LED and integrated conductor tracks are arranged.

This method is inventively created by the totality of the features of claim 1 5.

Embodiments of the invention will be described below with reference to the accompanying drawings. Fig. 1 shows a plan view of four lighting devices according to the invention.

Fig. 2 shows the rear view of the basic body of the lighting devices of FIG. 1 . Fig. 3 shows the lid of the four lighting devices of FIGS. 1 and 2.

Fig. 4 shows a plan view of an adhesive strip with light-emitting diodes for the light-emitting devices from FIGS. 1 to 3.

Fig. 5 shows a side view of the adhesive strip from FIG. 4th

Fig. 6 shows a cross-sectional view of a first embodiment of a lighting device.

Fig. 7 shows a cross-sectional view of a second embodiment of a lighting device according to the invention. Fig. 8 shows a cross-sectional view of another embodiment with a central web.

The Fig. 1 to 3 show four lighting devices whose basic body 1, 2, 3 and 4, respectively, have the shape of the letters "B", _> , A "," L "and" L ".

Each basic body 1 - 4 consists of a translucent plastic, in particular acrylic glass. In the Fig. 2, the rear views of the main body 1 - 4 are shown. It can be seen that the rear sides of the base bodies 1-4 are milled over the largest area of their surface in such a way that a thin edge web remains in each case at the edges. In the case of a simple letter, such as the letter "L", the milled cavity on the rear side of the main body 3 or 4 leads to a peripheral web 10 or 11 surrounding the outer periphery of the latter A typical letter may have a height of the order of 200 mm and a width of between 1 00 mm and 200 mm The thickness of the main body may, for example, be between 20 mm and 35 mm The width of the body naturally depends on the contour of the letter and is typically between 20 mm and 60 mm.

More complex letters, such as the letter "A", lead to several edge webs The main body 2 of the letter "A" has a peripheral outer edge web 8 and a peripheral inner edge web 9. In the letter "B", the main body 1 has a peripheral outer edge web 5 and two encircling inner edge webs 6 and 7. It can also be seen in FIG. 2 that adhesive strips 1 3 (FIGS. 4 and 5), which carry light-emitting diodes 1 2, are glued on each peripheral edge web 5-1 1 2 can be seen more clearly in Figures 4 and 5. These are surface-mounted components, also referred to in English as "surface mounted devices" (SMD). The SMD components are mounted on flexible strips, in which the interconnects are integrated, which conduct electricity to the LEDs 1 2.

The Fig. 4 and 5 show the adhesive strips 1 3, with which the light-emitting diodes 1 2 on the inside of the edge webs 5 - 1 1 of the main body 1-4 are applied. The adhesive strips have a width of for example 1 0 mm. The distance between two light-emitting diodes 1 2 to each other is typically between 20 mm and 40 mm. Between two light-emitting diodes 1 2, the adhesive strips 1 3 can be cut at appropriate locations. In the Figs. 4 and 5, further electronic components between the LEDs 1 2 can be seen. These can serve the color control of the LED. Furthermore, at one end of the adhesive strip 1 3 a connection cable 14 can be seen for the power supply.

The LED 12 can be monochromatic LED in any color. It is also possible to use in each case three individually controllable individual diodes with different color components (eg red, green and blue) existing SMD LEDs, which can be adjusted by means of suitable control electronics to bel iebige colors. The Fig. 3 shows the covers 1 5 to 1 8 of the lighting devices 1 - 4. The covers 1 5 - 18 have a plurality of screw holes 28 for receiving the heads of fastening screws 25 (FIGS. 6 and 7). The fastening screws 25 are used to attach the cover 1 5 - 1 8 to the bodies 1 - 4 and on the other fastening the cover 1 5 - 1 8 to a support frame or support profile, which carries the light-emitting devices to a word composite and fixed in a certain spatial position.

The Fig. 6 and 7 show cross-sectional views through two embodiments of a lighting device according to the invention. In each case, a section through the main body 3 is shown. The main body 3 consists essentially, that is, more than half of its height between the front and the back, of a solid, light-permeable acrylic glass section 1 9. On the front side of the translucent acrylic glass section 1 9, another translucent acrylic glass section glued on, which has the color of the letter imaged by the light emitting device and a colored, translucent cover layer 20 of the Grundkör- pers 3 forms. The substantially translucent, solid acrylic glass section 1 9 of the body before the back cutout serves to conduct and distribute the light of the light emitting diodes 12. The front, about 3 mm thick cover layer 20 of colored acrylic glass forms the visible surface from the outside, which is as bright and evenly lit in the desired color.

The side walls of the base body 3 are each provided with an opaque coating 21, e.g. a paint layer or paint layer provided. This can be, for example, white or aluminum colors and reliably prevents unwanted leakage of light from the side walls.

It can be seen that the cavity 24 substantially in the rear region of the translucent portion 19 of the main body. 3 is milled. The depth of the cut must correspond at least to the width of the adhesive strip 1 3, which is for example about 1 0 mm. Consequently, the edge web 1 0 is preferably 1 0 to 1 5 mm high. The remaining in front of the edge web 1 0 translucent portion 1 9, that is, the massive part of the base body 3 extends at least over the height of the edge web and thus at least over half the height of the base body 3. In the embodiment of FIG. 6, the adhesive strip 13 is bonded directly to the inner surface of the peripheral edge web 10 of the base body 3. In the embodiment in FIG. 7 is first glued to the edge web 10 of the base body 3, a thin metal sheet, which is a heat-conducting

Layer 22 forms. The adhesive strip 1 3 is glued to this metal sheet 22. The metal sheet 22 distributes the waste heat of the LEDs 1 2 evenly over the entire surface of the peripheral edge web 1 0. In this way, local overheating of the peripheral edge web 1 0 avoided and good heat dissipation of the waste heat of the LEDs 1 2 can be ensured.

In the embodiment in FIG. 7, the light-transmissive portion 1 9 of the main body 3 extends to the back of the main body 3. This causes light from the LEDs 1 2 from the rear edge web 1 0 emits backwards. This can be a very desirable effect. The light radiating backwards forms a corona around the illuminated letter. But there are also cases in which a radiation of light to the rear is not desired. In this case, as shown in Fig. 6, the rear portion 23 of the edge web 1 0 formed of an opaque plastic. This opaque portion 23 in conjunction with the opaque painted side surface prevents the escape of light of

LEDs 1 2 on the entire lighting device, with the exception of their front visible from the front. The opaque portion 23 becomes preferably applied to the back of the translucent portion 1 9 prior to milling the cavity 24.

The back of the lighting device is closed by the lid 1 7. The cover 1 7 may for example consist of aluminum. It is preferably provided on the inside with a light, in particular white or metallic color. The light of the LEDs 12 is thus through the cavity

24 facing side reflected and thrown towards the front of the lighting device. However, the lid 17 may also be made of colored or white translucent material (e.g., acrylic glass) when light is desired to exit from the back of the illuminated letter.

The cover 1 7 is fixed by means of fastening screws 25 to the base body 3. The fastening screws 25 are screwed into threaded bores 27 within the main body 3. By the light-conducting property of the base body 3 is avoided that the fastening screws

25 cast shadows on the front of the base 3. Between the peripheral edge web 1 0 and the lid 1 7, a seal 26, for example made of silicone, is arranged. The seal avoids the ingress of dirt into the cavity 24 and can avoid the escape of light through the gap between the lid 1 7 and edge web 1 0 when choosing an opaque sealing material.

It is also possible to provide a lighting device that emits only to the rear. In this case, the front colored translucent cover layer 20 may be omitted. Instead, the front of the illuminated lettering may be provided with an opaque paint. In this case, of course, the rear portion of the edge webs is translucent. The height of such a trained luminous letter can be further reduced. Essentially, the main body only forms a housing for the light-emitting diodes. This lighting device may have a height from the back to the front in the order of 20 mm. The Fig. 8 shows an embodiment of the lighting device with a central web 29. Otherwise, the embodiment is substantially identical to the embodiment of FIG. 6 match. Only the position of the fastening screw 25 is offset to the left, so that it does not extend through the central web 29.

The central web 29 is generated during milling of the cavity 24. The diameter of the milling cutter corresponds to the distance between the mutually opposite surfaces of central web 29 and one of the edge webs 1 0. Due to the cutting edges of the milling cutter, a partially translucent and diffuse-reflecting structure is formed on the central web 29 on both sides. On the one hand, this surface structure allows the light to penetrate from the laterally arranged light-emitting diodes 1 2 and, on the other hand, throws this light back diffusely. This ensures that the illumination of the translucent acrylic glass section 1 9 and thus the visible brightness on the front does not decrease, especially in its central region. In translucent acrylic glass sections 1 9 with a large width, that is, when the opposite inner sides of the edge webs 1 0 have a large distance from each other, there is a risk that the luminosity of attached to the edge webs 1 0 diodes 1 2 is not sufficient to the middle Sufficiently illuminate the area. Since the surface of the central web 29 diffusely reflects the light of the light emitting diodes 1 2, a further light source, which in particular ensures the illumination of the central region, is formed in the center of the translucent acrylic glass section 19 by the center web 29. The central web 29 protrudes in the illustrated embodiment to the cover 1 7, which covers the cavity 24.

_{* * * * * * *} LIST OF REFERENCE NUMBERS

1 main body of the letter "B"

2 main body of the letter "A"

3 main body of the letter "L"

4 main body of the letter "L"

5 edge bridge

6 edge bridge

7 edge bridge

8 edge bridge

9 edge bridge

10 edge bridge

11 edge bridge

12 LED

13 adhesive strips

14 connection cable

15 lids

16 lids

17 lid

18 lids

19 translucent acrylic glass section

20 colored translucent cover layer

21 opaque coating

22 sheet metal, heat-conducting layer

23 opaque section

24 cavity

25 fixing screw

26 seal

27 threaded hole

28 screw hole

29 central pier

_{* * * * * * ** * * * * * *}

Claims

claims

1 . Lighting device with a base body (1 -4) made of translucent material in which at intervals to each other a plurality of light emitting diodes (1 2) are arranged, which are applied to a flexible adhesive strip (1 3) with integrated conductor tracks,

characterized in that

- In the base body (1 -4) at the back a one-sided open cavity (24) is milled, wherein the width and length of the cavity (24) is slightly smaller than the width and length of the base body (1 -4), so that at least one along the periphery of the base body (1 -4) extending, closed edge web (5-1 1) in the rear region of the main body (1 -4) runs,

- The adhesive strip (1 3) with the light-emitting diodes (1 2) over the entire length of the edge web (5-1 1) is applied on the inside, that light-emitting diodes (12) on the mutually facing inner sides of opposing edge land sections are arranged

- Is illuminated by the light-emitting diodes (1 2) on the lateral edge web (5-1 1) the massive light-conducting portion (1 9) of the main body (1 -4) in front of the cavity (14), so that a high luminance on the visible front arises, and

- The cavity (24) is closed at the back of the lighting device by a lid (1 5-1 8).

2. Lighting device according to claim 1, characterized in that the distance between the back and the front of the lighting device is up to 40 mm.

3. A lighting device according to claim 1 or 2, characterized in that the base body (1 0) on the said cavity (24) gegenüberl lying front has a light-permeable, colored cover layer (20).

4. Lighting device according to one of the preceding claims, characterized in that the edge web (5-1 1) has a back l opaque portion (23).

5. Lighting device according to one of the preceding claims, characterized in that the cover (1 5-1 8) consists of opaque material.

6. Lighting device according to claim 5, characterized in that the cavity (24) facing side of the lid (1 5-1 8) has a color which reflects the light of the light emitting diodes (1 2) and throws in the direction of the front of the lighting device ,

7. Lighting device according to claim 1 or 2, characterized in that the cover (1 5-1 8) consists of translucent material.

8. Lighting device according to one of the preceding claims, characterized in that the cover (1 7) with a fastening screw (25) on the base body (3) is fixed and that the base body (3) has a threaded bore (27) into which the Fixing screw (25) is screwed in.

9. Lighting device according to one of the preceding claims, characterized in that on the inside of the edge web (1 0) a heat-conductive layer (22) is arranged, on which the flexible adhesive strip (1 3) is glued.

1 0. A lighting device according to any one of the preceding claims, characterized in that a side wall extending from the front side to the back side is provided with a light-impermeable coating (21).

1 1. Lighting device according to one of the preceding claims, characterized in that the distance between two light-emitting diodes (1 2) is in the range between 5 mm and 40 mm.

1 2. Lighting device according to one of the preceding claims, characterized in that the base body (1 -4) consists of opaque, translucent material.

1 3. Lighting device according to one of the preceding claims, characterized in that in the center of the cavity, a central web (29) made of translucent material, in particular acrylic glass, which protrudes from the base body (3) and substantially parallel to

Edge web extends.

14. Lighting device according to claim 13, characterized in that the central web (29) has a diffuse-reflecting surface.

1 5. A method for producing a lighting device comprising a base body (1 -4) made of light-permeable material, in which a flexible adhesive strip (1 3) with light emitting diodes (1 2) arranged at intervals and integrated conductor tracks are arranged,

characterized by the following steps:

- In the rear region of the body is a one-sided open cavity (24) with at least one along the periphery of the base body (1 -4) extending, closed edge web (5-1 1) milled, wherein the width and length of the base body (1-4 ) is slightly smaller than the width and length of the main body (1 -4);

- The adhesive strip (1 3) is so stuck over the entire length of the edge web (5-1 1) on the inside that light-emitting diodes (1 2) are arranged on the facing inner sides of opposite edge land sections and the solid l ichtleitenden body (1 9) in front of the cavity;

- The cavity (24) is closed at the back of the lighting device by a lid (15-1 8).