WO2008040690A1

WO2008040690A1 - Led light module having a reflector

Info

Publication number: WO2008040690A1
Application number: PCT/EP2007/060350
Authority: WO
Inventors: Martin Michel; Mathias Benz; Alex Janutin; Urs A. Weidmann
Original assignee: Innoled Ag
Priority date: 2006-10-02
Filing date: 2007-10-01
Publication date: 2008-04-10
Also published as: DE502007006514D1; CH698577B1; ES2361392T3

Abstract

A light module comprises a base element (1), which has a base (3) and two side walls (4, 5) opposing each other and disposed at a distance from the base (3), and a cover plate that can be attached to the base element (1), wherein the cover plate is translucent and diffusely scatters incident light. A strip (8) is attached on each of the two side walls (4, 5), the strip being inclined in relation to the side wall (4, 5) at a predetermined angle. LEDs (10) are mounted on the side of the strip (8) facing the base (3) to illuminate the base (3). The base (3) is configured in a light reflecting manner, wherein the reflection properties of the base (3) are different in the region of the center between the two side walls (4, 5) than in the vicinity of the two side walls (4, 5). The light module ensures uniform distribution of brightness across the entire diffusely scattering translucent cover plate.

Description

LED light module with reflector

The invention relates to a light module referred to in the preamble of claim 1 Art.

Such light modules are available in many designs, on the one hand as modules, whose dimensions correspond to a predetermined standard and which are joined together to form a coherent ceiling or wall, which in turn serves as a means of illumination. On the other hand, there are also modules with special masses for specific applications, e.g. as a lighting device in a kitchen. Furthermore, such modules are used as light boxes for labels, signaling, as well as advertising purposes and as scoreboards. Conventional light modules usually contain fluorescent lamps whose disadvantages are the high power consumption and the limited life.

The invention has for its object to develop a light module that has a lower power consumption and virtually no maintenance during the entire life.

The stated object is achieved according to the invention by the features of claim 1.

The light module according to the invention contains commercially available light-emitting diodes, which are generally known as LEDs (light-emitting diodes). Their power consumption is the fraction of the power consumption of a fluorescent, incandescent or halogen lamp with the same light output. The light module comprises a base element and a cover plate that can be detachably fastened to the base element. The cover plate is translucent, but not transparent. It diffuses incident light diffusely. The bottom element has a bottom and two projecting from the ground, opposite side walls. On each of the two side walls, a bar is attached, which is inclined relative to the side wall at a predetermined angle. On the side of the ledge facing the floor, there are LEDs that shine towards the floor. The floor is designed to reflect light. The reflection properties of the floor are changed towards the two side walls in order to compensate for the light radiation of the LEDs falling off towards the center and reflecting from the ground. In the room, which is bounded by the floor element and the cover plate, there is air. Waveguides and / or optical fibers are not needed. This space and thus the entire light module is therefore free of light-conducting components.

The floor is subdivided into a multiplicity of first and second partial surfaces. The area occupied by the first partial areas increases in a certain area compared to the area occupied by the second partial areas with increasing distance from the side wall to the center between the side walls. In a preferred embodiment, the first partial surfaces differ from the second partial surfaces in the reflection characteristic: the first partial surfaces diffuse the light non-diffusely, whereas the second partial surfaces scatter the light diffusely in comparison thereto. The first partial surfaces are for example made of high-gloss aluminum and have a reflective surface, while the second part surfaces are provided with a matt white surface. In an alternative embodiment, the first partial areas differ from the second partial areas in the reflectivity, the reflectivity Ri of the first partial areas being greater than the reflectivity R _{2 of} the second partial areas.

The invention will be explained in more detail with reference to embodiments and with reference to the drawing. The figures are not drawn to scale.

1 shows in plan view a bottom element of a light module,

FIG. 2 shows the bottom element with the cover plate of the light module applied in a section along the line II of FIGS. 1, 3, 5 illustrate possibilities for locally changing the reflectivity of the bottom of the floor element by means of a structured reflection layer, and FIG Details of the invention with reference to a section of Fig. 3rd

The light module according to the invention comprises a bottom element and a cover plate that can be detachably fastened to the bottom element. Fig. 1 shows the bottom element 1 in plan view. 2 shows the bottom element 1 with the cover plate 2 in a section along the line II of FIG. 1. The bottom element 1 consists of a bottom 3 and at least two opposing side walls 4 and 5 projecting from the bottom 3. In many applications However, the bottom element 1 contains four side walls 4 to 7, which form a peripheral wall. On the first side wall 4 and on the second, opposite side wall 5, a bar 8 is attached. The bar 8 is inclined relative to the side wall 4 and 5 at a predetermined angle α. On the bottom 3 side facing the strip 8 strips 9 are mounted with light emitting diodes 10 (LED). Such strips 9 are commercially available in many designs. The strips 9 comprise, for example, LED's 10 arranged in a row, all of which emit white light, or LED's 10 according to the RGB standard, from which every third red light, green light or blue light alternately emits light. A control unit controls the LED 's 10. If red, green and blue LED's 10 are present, then the controller can drive the LED's 10 so that the light module illuminates in any color. The space bounded by the bottom 3, the side walls 4, 5 and optionally 6, 7 and the cover plate is filled with air, but this space is not sealed airtight to the environment. Light-conducting elements such as waveguides and / or light guides are not needed.

The LED's 10 illuminate the bottom 3, which is light-reflecting and serves as a reflector. The light emitted by the LED's 10 toward the ground light is therefore reflected at the bottom 3 and passes through the cover plate 2 into the open. The cover plate 2 is translucent, but not transparent. Their task is to diffuse the incident light diffusely in all directions. The cover plate 2 is for example a milky cloudy Plexiglas plate. The angle α is chosen so that the light cone 11 of the LED's 10 in the region 12 of the center of the bottom 3 partially overlap. The lighting of the bottom 3 by the LED's 10 is not uniform, because the intensity of the LED's 10 radiated light decreases with increasing distance from the side wall 4 and 5 respectively. The reflection properties of the bottom 3 are therefore changed from the middle between the side walls 4 and 5 against the side wall 4 and 5, so that the cover plate 2 appears evenly bright to the human eye. In order to achieve the highest possible brightness of the light module for a given power of the LED's 10, the reflectivity of the bottom 3 is advantageously at a maximum, at least in the middle. In FIG. 2, the arrows 13 of equal length illustrate the uniformity of the light radiation of the light emitted by the cover plate 2.

The bottom 3 of the bottom element 1 advantageously has a surface that is as white and as matt as possible, which diffuses incident light as diffusely as possible and onto which a reflection layer structured in the surface is applied, which consists, for example, of high-gloss aluminum. The bottom 3 is therefore divided into at least a first partial surface made of high-gloss aluminum and second partial surfaces with a matt, white surface. The color of the white surface is, for example, what is known as the whitest white, "traffic white 9016." The matt surface reflects the incident light diffusely.The color white causes a very large proportion of the incident light to be scattered back and absorbs only a very small portion of the incident light On the other hand, the reflection layer reflects the incident light non-diffusely, since both the first and the second sub-areas have a high reflectivity, resulting in a high luminous efficacy.The subdivision of the surface of the bottom 3 into first and second sub-areas with different reflection characteristics, namely diffuse reflection and non-diffuse reflection, causes the edge of the cover plate 2 appears as bright as the middle parts of the cover plate second

Another solution consists in subdividing the bottom 3 into first and second subareas which differ in their reflectivity, the reflectivity Ri of the first subareas being greater than the reflectivity R _{2 of} the second subareas. The bottom element 1 can be made of metal, for example, whose surface is stove-enamelled, or made of plastic. The reflectivity of such a surface is relatively low, ie the surface acts as an absorption layer, which absorbs a large proportion of the incident light. On the bottom 3, a surface-structured reflection layer is applied, so that the reflectivity of the bottom 3 increases from the side walls 4 and 5 toward the center between the side walls 4 and 5. The reflective layer may be, for example, a reflective foil or a vapor deposited metal layer or simply a white surface.

In the following, various examples are presented how the reflection layer can be structured in the solutions described above.

example 1

Fig. 3 shows the bottom 3 and the side walls 4 to 7 in plan view. The drawing is not drawn to scale. The floor 3 is divided into two areas: a first contiguous area 14 and a second area 15 complementary to the first area 14 (The area 15 consists of two separate subregions, which are located on the left and right of the first area 14 in FIG. 3). The first region 14 of the bottom 3 is covered with a reflection layer 16. The edge 17 of the first area

14 is formed on the side wall 4 and on the side wall 5 facing side sawtooth.

FIG. 4 shows the region C bounded by a dashed line in FIG. 3 in order to explain details of the invention. (The first side wall 4 is shown only to illustrate the position of the region C relative to the first side wall 4.) The entire bottom 3 of the bottom element 1 is by definition subdividable into first part surfaces 19 with first reflection properties and second part surfaces 20 with second reflection properties. As can be easily seen from FIG. 4, the surface occupied by the first partial surfaces 19 increases in the area of the saw tooth with increasing distance from the side wall 4 in comparison to the surface occupied by the second partial surfaces 20.

A field test for a light module having a size of 60cm * 60cm, according to a widely used standard, has shown that the tips of the sawtooth do not extend to the center (represented by the line 18) between the two sidewalls 4 and 5 but that are already relatively short tips with a length B of 5 to 10 cm sufficient.

The shape of the edge 17 between the two regions 14 and 15 is not limited to the sawtooth shape. For example, the edge 17 may also be sinusoidal, wavy, etc., or bounded by exponential curve curves.

If the first partial areas 19 are designed such that they reflect the incident light non-diffusely, and the second partial areas 20 so that they reflect the incident light diffusely, then this means that light emitted by the LED's 10, the light on the first Area 14, as reflected by a mirror, and that light emitted by the LED's 10, that on the second area

15 hits, is very wide scattered. In the region of the sawtooth, the reflection characteristic of the bottom 3 thus changes.

Example 2

In this example, shown in FIG. 5, the reflection layer 16 does not form a contiguous area but consists of a multiplicity of first partial areas 19 and second partial areas 20. The density of the first partial areas 19 increases from the side walls 4 and 5 toward the center , For example, the first faces 19 are dots as shown. The points can be distributed regularly or randomly. The size of the dots is of minor importance, it can vary from a few microns to a few millimeters or even centimeters. This example is particularly suitable if the reflection layer 16 is produced by vapor deposition of metal or by spraying on a material which is otherwise reflective, for example by screen printing. In this example as well, the area occupied by the first partial surfaces 19 increases in comparison with the area occupied by the second partial surfaces 20 with increasing distance from the side wall 4. One Area 12, which is located in the middle between the two side walls 4 and 5, is completely covered with the reflection layer 16, since it is a question that the light module glows as bright as possible for a given power of the LED's 10.

In order to achieve a uniform brightness of the light module, it is often necessary to provide further measures to avoid that the LEDs 10 illuminate the other side walls 6 and 7. This could in fact lead to undesirable, brighter areas on the cover plate 2. To prevent this, there are two possibilities:

1. The two outermost LEDs 10 of a strip 8 are arranged at a predetermined minimum distance A (FIG. 1) to the adjacent side wall 6 or 7, so that no or almost no light emitted directly by the LED's 10 impinges on the side walls 6 and 7 , In the example shown in FIG. 1, in the case of one strip 8, the LEDs 10.1, 1 and 10.1, n, in the other strip 8, the LEDs 10.2, 1 and 10.2, n.

2. The side walls 6 and 7 are coated from a material or on the side facing the bottom 3 with a material which has a high light absorption capacity and low light reflectance, respectively. The absorption capacity for light is so great that the cover plate 2 appears evenly bright to the human eye.

2 B. The sidewalls 6 and 7 may alternatively also be made with a very white and matt surface to diffuse the incident light, i. spread as wide as possible.

The options mentioned can also be combined. They effect, individually or in combination, that the cover plate 2 is uniformly bright and therefore has no brighter areas.

The light module according to the invention ensures uniform brightness distribution over the entire, diffusely scattering, translucent cover plate 2.

It is also possible that a plurality of light modules have a common cover plate 2.

Claims

1. Light module, with a bottom element (1) having a bottom (3) and two from the bottom (3) projecting, opposing side walls (4, 5), and one on the bottom element (1) attachable cover plate (2), the is translucent and diffuses incident light diffusely, the space bounded by the floor, the side walls and the cover space being filled with air, characterized in that on each of the two side walls (4, 5) is fixed a bar (8) facing the side wall (4, 5) at a predetermined angle (α) is inclined, that on the bottom (3) facing side of the strip (8) LED's (10) are mounted, which illuminate the bottom (3), and that Floor (3) is designed to reflect light, wherein the reflection properties of the bottom (3) in the region of the middle between the two side walls (4, 5) are different than in the vicinity of the two side walls (4, 5).

2. Light module according to claim 1, characterized in that the bottom (3) in first partial surfaces (19) and second partial surfaces (20) is subdivided, which have different reflective properties, and that of the first partial surfaces (19) occupied area in comparison to the area occupied by the second sub-areas (20) in an area between the first side wall (4) and the middle between the two side walls (4, 5) and between the second side wall (5) and the middle between the two side walls (4, 5) increases with increasing distance from the corresponding side wall (4, 5).

3. Light module according to claim 2, characterized in that the first partial surfaces (19) reflect incident light non-diffusely and that the second partial surfaces (20) diffuse incident light diffusely.

4. Light module according to claim 3, characterized in that the first partial surfaces (19) have a reflective surface and the second partial surfaces (20) have a matt, white surface.

5. Light module according to claim 2, characterized in that the first partial surfaces (19) have a reflectance Ri and the second partial surfaces (20) have a reflectance R ₂ , wherein the reflectance Ri is greater than the reflectance R ₂ .

6. Light module according to one of claims 1 to 5, characterized in that the light module has two further side walls (6, 7) and that the two outermost LEDs (10) of a bar (8) in a predetermined minimum distance (A) to the other Side walls (6, 7) are arranged.

7. Light module according to one of claims 1 to 5, characterized in that the light module has two further side walls (6, 7) whose absorption capacity for light on the bottom (3) facing side is so large that the cover plate (2) appears uniformly bright to the human eye.

8. Light module according to one of claims 1 to 5, characterized in that the light module has two further side walls (6, 7), whose bottom (3) facing side has a matte, white surface.