Light fixture with LED light source and light guide plate

Abstract

Lamp (100), having • a preferably elongated LED light source (50, 51) for generating a light, • a light guide plate (10), wherein the LED light source (50, 51) is arranged on a beam edge surface (12) of the light guide plate (10) such that the light generated by the LED light source (50, 51) is emitted into the light guide plate (10) via the beam edge surface (12) and emitted via at least one flat side (11) of the light guide plate (10), • a support element for supporting the optical fiber plate (10), as well as • a pressure element (40) which is arranged between the light guide plate (10) and a support element (90) opposite the support element with respect to the light guide plate (10) and is designed to press the light guide plate (10) in the direction of the support element, characterized in that the pressure element (40) forms at least one, preferably several, spring elements (45) which extend from a planar base area (41) of the pressure element (40) and are supported on the support element (90) or a component arranged in front of the support element.

Description

[0001] The present invention relates to a luminaire which has a preferably elongated LED light source and a light guide plate, wherein the light of the LED light source is radiated into the light guide plate via an incident radiation edge surface of the light guide plate and is emitted via at least one flat side of the light guide plate.

[0002] Luminaires of this type, which utilize this so-called "edge-lit" technology, are designed to emit light as uniformly and as widely as possible. The use of a light guide plate and the associated arrangement of the LED light source at one edge of the plate makes it possible to realize the component responsible for light generation and emission with an extremely low installation height. Accordingly, such luminaires are preferably used as suspended pendant luminaires or floor-standing luminaires, as the low installation height can have a particularly positive effect on the appearance of the luminaire.

[0003] With regard to the efficiency of light output in such luminaires, it is crucial that the LED light source and the light guide plate are precisely positioned relative to one another. The arrangement of the components responsible for light distribution and light output is generally carried out in a so-called sandwich construction, in which several layers are arranged one behind the other in a direction perpendicular to the plane of the light guide plate. These layers comprise, in particular, the light guide plate and, if necessary, other plate-shaped components with which the desired light output can be optimized. Such additional components can be, for example, a diffuser plate, films for controlling the light output and / or reflective layers. As already mentioned, these are placed on top of one another in a sandwich-like manner and then stored within the housing of the luminaire.

[0004] One problem here is that these plate-like components or parts have a certain tolerance in their thickness due to manufacturing. Since these tolerances can vary, it can be difficult to ensure that all layers are perfectly aligned. In particular, this can lead to a slight shift in the position of the light source relative to the light guide plate within the housing, which would then significantly reduce the efficiency of light coupling and distribution.

[0005] To avoid this problem, it is known from the prior art to additionally use a compressible, plate-shaped element. This element, typically formed by a foam sheet, is placed in the housing in such a way that it compresses the various components responsible for light emission. The aim is to compensate for the differences in layer thickness while simultaneously exerting pressure on the entire sandwich construction, ensuring that the individual layers cannot shift relative to each other and, in particular, that the desired positioning of the light guide plate relative to the LED light source is maintained.

[0006] However, the production of such foam boards involves a certain amount of effort, as they are cut from a corresponding foam block. This process, in turn, can lead to higher tolerances, meaning the reliable functionality of the foam board cannot be guaranteed over the lifetime of the luminaire. Another problem is that the corresponding material must be disposed of at the end of its service life, which is a complex process.

[0007] The present invention is therefore based on the object of offering a novel solution which ensures reliable positioning of a light guide plate with respect to an LED light source with reduced effort.

[0008] The object is achieved by a luminaire having the features of claim 1. Advantageous developments of the invention are the subject of the dependent claims.

[0009] According to the present invention, analogous to the foam plate explained above, it is also provided to press the light guide plate towards a support element with the aid of a corresponding pressing element, so that the light guide plate is correctly positioned with respect to an associated LED light source. According to the present invention, however, a pressing element is now used which forms at least one, preferably several spring elements that extend from a flat base area and are supported on a suitable support element or a component of the luminaire arranged in front of the support element. In this way, the pressure required for exact positioning is exerted on the light guide plate, but the design of the pressing element according to the invention allows it to be manufactured simply and inexpensively.At the same time, the pressure element according to the invention can be used more flexibly than the foam plate and can be used efficiently in different constructions.

[0010] According to the present invention, a luminaire is proposed which comprises: • a preferably elongated LED light source for generating a light, • a light guide plate, wherein the LED light source is arranged on an incident irradiation edge surface of the light guide plate, such that the light generated by the LED light source is irradiated into the light guide plate via the incident irradiation edge surface and emitted via at least one flat side of the light guide plate, • a support element for supporting the light guide plate and • a pressing element which is arranged between the light guide plate and a support element which is opposite the support element with respect to the light guide plate and is designed to press the light guide plate in the direction of the support element, wherein according to the invention the pressing element forms at least one, preferably several spring elements which extend from a flat base region and are supported on the support element or a component arranged in front of the support element.

[0011] The spring elements of the pressure element according to the invention are preferably formed by fingers that extend in an arc from the flat base area toward the support element. In particular, the pressure element can be formed in one piece, with the pressure element particularly preferably being formed by a plastic part, preferably an injection-molded plastic part. This results in a relatively simple possibility for producing the pressure element, wherein the manufacturing tolerances are significantly lower compared to the previously used foam board, and due to the corresponding design of the spring elements, larger tolerances of the sandwich-like arrangement of the lamp can be compensated.

[0012] The base area of ​​the pressure element preferably rests flat against the light guide plate or a reflector element resting on the light guide plate. This ensures that pressure is applied evenly across the sandwich construction, preventing the occurrence of localized loads. This ensures that a homogeneous light distribution is maintained and that localized brightness differences cannot occur.

[0013] The support element of the luminaire is preferably formed by a heat sink element arranged on the rear side of the luminaire. At least one additional flat cover element can be arranged between the support element and the pressure element. This can prevent light from escaping toward the rear. However, it may also be possible to provide the cover element with one or more openings that allow indirect light emission, for example, toward the top.

[0014] The luminaire preferably has a support element for holding the LED light source. This support element can, in particular, be angled and comprise a first web on which the LED light source is arranged, as well as a second web, which is oriented, for example, at right angles to the first web and forms a support surface for the light guide plate.

[0015] It can preferably be provided that the pressing element has an end region that engages in a positioning opening in the support element. This enables precise positioning of the pressing element and ultimately further simplifies the installation of the luminaire. Furthermore, it is ensured that the pressing element remains in the desired position throughout the duration of the luminaire's use and thus performs its function permanently and reliably. It can particularly preferably be provided that the end region of the pressing element is at least slightly deformable in a plane parallel to the light guide plate. If changes in the dimensions of individual components of the luminaire occur due to temperature fluctuations, these can be absorbed by the pressing element if necessary, without there being a risk of the component leaving its desired position.

[0016] The LED light source preferably comprises an elongated circuit board on which several LEDs are distributed. In particular, the length of the circuit board can correspond to the length of the incident light edge of the light guide plate.

[0017] The luminaire according to the present invention preferably further comprises a housing that forms a light exit opening. A further disc-like diffuser element can be arranged within the light exit opening, through which the light is ultimately emitted. As already mentioned at the beginning, this can be, in particular, a pendant luminaire or a floor-standing luminaire.

[0018] The invention will be explained in more detail below with reference to the accompanying drawings. They show: Fig. 1 shows a sectional view of a lateral region of a luminaire designed according to the invention; Fig. 2 a top view of the luminaire open at the top; Fig. 3 and Fig. 4 views of the pressure element used in the lamp according to the invention; and Fig. 5 to 7 views of a second embodiment of a luminaire according to the invention.

[0019] Fig. 1 and Fig. 2 show views of a lamp 100 designed according to the invention, which in this case is a floor lamp. Strictly speaking, Fig. 1 and Fig. 2 only shows the so-called lamp head of a floor lamp. This is located at the upper end of a column, which is not shown for reasons of clarity, since the inventive solution relates in particular to the design of the components responsible for light generation and light emission. Accordingly, the lamp head can be arranged in any desired manner on a corresponding support. In the same way, however, the lamp 100 could also be suspended from the ceiling of a room to be illuminated using appropriate measures.

[0020] The housing 110 of the luminaire 100, which in this case is approximately rectangular in shape, accommodates all essential components for light generation and light emission. It forms a light exit opening 115 towards the front or underside, through which the (primary) light emission of the luminaire 100 takes place. The luminaire housing 110 is designed like a frame and is closed or covered towards the rear by further components, which are Fig. 1 and Fig. 2 are only partially shown.

[0021] The luminaire frame itself is formed by surrounding walls which are angled and form, on the one hand, vertical side walls 111 and, on the other hand, a web 112 projecting inwards on the underside, which frames the light exit opening 115. This surrounding web 112 serves as a support surface for numerous components of the luminaire 100, whereby additional components can also be attached directly to the inside of the side walls 111 by means of suitable support elements. Fig. 2, which shows the luminaire 100 in a partially open state at the top, the operating devices 120, via which the lamps are supplied with power, as well as corresponding connection components 121 for supplying power to the operating devices 120.

[0022] However, the present invention relates in particular to the lighting means and other optical components responsible for light generation and light emission, as well as to the problem of positioning them reliably and permanently in a suitable manner relative to one another.

[0023] It is provided that the light guide technology already known from the prior art is used in the luminaire 100 according to the invention, in which the light from lamps is distributed by means of a plate-like light guide element and is emitted as homogeneously and as widely as possible.

[0024] The central component of the so-called light engine of the luminaire 100 is therefore a light guide plate 10, which is arranged in the lower area of ​​the luminaire housing 110. The underside 11 of this light guide plate 10 forms the flat side via which the light is output and thus the light is emitted. The light is coupled into the light guide plate 10 via an edge surface 12 aligned perpendicularly thereto, in the illustrated embodiment via the surface provided at the left end area of ​​the light guide plate 10. Depending on how much light is to be emitted by the luminaire 100 in total, an arrangement of lamps and thus light can also be coupled in at other edge areas of the light guide plate 10. For the present case, it is sufficient to use the Fig. 1 shown left end area of ​​the luminaire 100.

[0025] Coupling into the light guide plate thus takes place via the edge surface 12, wherein this is the light from an LED light source which is arranged in the luminaire housing 110 in association with this edge region 12. The LED light source is preferably formed by an elongated LED board 50 on which a plurality of LEDs 51 are distributed. The arrangement of the LEDs 51 preferably extends over the entire length of the associated edge surface 12 of the light guide plate 10, so that the most uniform light coupling possible can be achieved. In this case, additional structures can be provided in the region of the edge surface 12 of the light guide plate 10. These structures are not shown in the figures, but contribute to achieving more efficient and homogeneous light coupling, which ultimately has a positive effect on the homogeneous light emission of the luminaire 100 as a whole.In this case, suitable lens-like structures or the like should be considered, with the aid of which the light emitted by the LEDs 51 is radiated into the light guide plate 10 as homogeneously as possible.

[0026] The arrangement of the LED lamps 50 within the luminaire housing 110 is carried out by means of a support element 60, which is arranged in the edge region of the luminaire housing 110. The support element is angled as shown and forms, on the one hand, a vertical wall 61 on which the LED circuit board 50 is arranged, as well as a horizontal web 62 formed on the underside. As shown in Fig. 1, the light guide plate 10 rests with its underside on this web 62, so that this or the carrier element 60 as a whole simultaneously forms a support element for the light guide plate 10.

[0027] The Fig. 1 and Fig. The luminaire 100 shown in Figure 2 also has components for emitting light towards the top. As can be seen particularly from the illustration in Fig. 1, an LED circuit board 80 with a plurality of LEDs 81 is arranged in the upper region of the luminaire housing 110. A cover element 85 arranged on this circuit board 80 is provided with corresponding openings 86 through which the light from the LEDs 81 is emitted towards the upper side. Other components of the luminaire 100 arranged above these additional LEDs 81 then also have corresponding openings or are designed to be translucent in such a way that the light from these LEDs 81 is emitted towards the upper side in the sense of indirect illumination. However, this is merely a supplementary measure for light emission, which plays no role in the inventive concept and is accordingly optional.

[0028] With regard to the primary light emission via the light guide plate 10 toward the underside, it must be considered that this must be precisely positioned with respect to the LEDs 51 to enable efficient coupling of the LED light. Even minor deviations in positioning could result in inhomogeneous coupling in terms of light intensity and / or light color, which would then result in a negative appearance and unacceptable light emission quality.

[0029] It should be noted that, in addition to the light guide plate 10, additional (flat) components are required to enable the most efficient and homogeneous light distribution and emission. For example, a plate- or foil-like reflector element 20 is typically provided on the rear side, i.e., on the top side of the light guide plate 10, which prevents unwanted light from escaping to the rear side. This reflector element 20 ensures that the light coupled into the light guide plate 10 is emitted essentially entirely to the underside.

[0030] A diffusing film or other structured film or plate can be provided on the underside of the light guide plate 10 to increase the efficiency of the planar light coupling. Furthermore, in this case, a plate-shaped diffuser 30 is also provided, through which the actual light emission takes place.

[0031] All of the components just explained, including the light guide plate 10, are therefore flat elements that are sandwiched one above the other within the luminaire housing 110 and at least partially lie directly on top of one another. Since these elements have certain tolerances regarding their thickness during production, there is a risk that simply arranging the components one above the other could result in the light guide plate 10 not being positioned precisely with respect to the LED lamps 50.

[0032] To avoid this, it is provided to press the light guide plate 10 onto a support that is fixedly aligned with respect to the LEDs 51, in this case, pressing the light guide plate 10 onto the web 62 of the support element 60. This ensures a defined positioning of the light guide plate 10, which, at the same time, due to the known positional relationship of the surface of the web 62 to the position of the LEDs 51, results in the edge surface 12 used for irradiating the light into the light guide plate 10 being correctly positioned.

[0033] This pressing of the light guide plate 10 onto the support element, in the present case onto the web 62, is achieved according to the invention with the aid of a pressing element, which is provided with the reference number 40 in the figures and is insulated in the Fig. 3 and Fig. 4 is shown.

[0034] This is preferably a one-piece plastic part, which can be manufactured in particular by injection molding. Fig. 3 and Fig. 4, this pressing element 40 initially has an elongated, approximately rectangular configuration, whereby according to the lateral representation of Fig. 4, a flat or planar base region 41 is initially formed. Extending from this base region 41, several curved, arcuate fingers 45 then extend toward the top, forming flexible spring elements that rest on a support element of the lamp 100 provided above the light guide plate 10. The illustrated configuration is selected such that the pressing element 40 can be manufactured relatively easily using an injection molding process. Accordingly, the arcuate fingers 45 extend above corresponding openings or recesses in the plate-shaped base region 41 of the pressing element 40, in order to enable easy demolding of the pressing element 40 from the injection molding tool.

[0035] The pressing element 40 according to the invention is then positioned, as can be seen in the figures, above the light guide plate 10, in the present case in particular above the reflector film 20 in the luminaire housing, so that the fingers 45 extend towards the top as shown. Here, the fingers 45 are supported with their end regions on a corresponding support element. In the present case, this is formed by a metal plate 90 provided on the underside of the further LED board 80, which also serves to dissipate the heat generated during operation. Because this support element 90 is firmly installed in the housing 110 of the luminaire 100, the pressing element 40 is clamped between the support element 90 and the light guide plate 10 by means of the fingers 45, so that the light guide plate 10 is pressed downwards as desired towards the corresponding support surface of the web 62.

[0036] The pressure element 40 rests with its base region 41 flat against the upper side of the light guide plate 10 or the reflector foil 20, so that relatively uniform pressure is exerted on the light guide plate 10. This also represents an advantageous effect of the pressure element 40 according to the invention, since local stress peaks, which would negatively impair a uniform distribution of the light, are avoided.

[0037] As particularly in Fig. 3, the pressing element 40 further comprises at both ends a hook-like end region 42 with a projection 43. This projection 43 can engage in a corresponding recess of the carrier element 60 for the LED board 50, as shown in Fig. 1. This engagement results in the pressing element 40 being able to be precisely positioned in a direction parallel to the longitudinal direction of the luminaire housing 110, and in this alignment being permanently maintained. Furthermore, the hook-like configuration of the end region 42 also results in this region being able to deform slightly if necessary and, in particular, in the ability to accommodate temperature-related length changes. This ensures that a reliable arrangement and alignment of the pressing element 40 according to the invention in the luminaire housing 110 is permanently guaranteed, even in the case of significant temperature differences.This defined arrangement of the pressing element 40 takes place in an analogous manner on the side opposite the LED light source, whereby - depending on the number of LED boards used - a further LED light source with associated carrier element 60 or another component can be provided which enables a corresponding engagement of the end region 42 of the pressing element 40.

[0038] The luminaire 100 is therefore assembled with regard to the components responsible for light generation and light emission in such a way that, after the LED illuminants 50 have been arranged in the luminaire housing 110, in a subsequent step, all of the flat components responsible for light distribution and light emission are loosely inserted into the luminaire housing 110. Subsequently, one or more of the pressing elements 40 according to the invention are placed on the sandwich-like structure and arranged in a defined manner on the LED carrier element 60 using the end regions 42. The subsequent arrangement of additional elements on the upper side then results in the pressing element 40 being clamped and thus exerting pressure on the light guide plate 10, so that it is arranged in the desired exact alignment and position with respect to the LED illuminants.This results in a simple installation of the luminaire, whereby an efficient and uniform light distribution is ensured by means of the pressure element according to the invention, since a desired exact alignment with regard to the light sources is guaranteed.

[0039] The Fig. 5 to 7 show a second embodiment of a luminaire 100 according to the invention, in which the same elements are provided with the same reference numerals. Fig. 5 and Fig. 6 show two different sections in the longitudinal direction, while Fig. 7 again shows a perspective sectional view of a lateral region of the luminaire 100.

[0040] This second embodiment is similar to that of Fig. 1 and Fig. 2. In particular, the Fig. 3 and Fig.The pressure element 40 shown in Figure 4 is used. The key difference is that no additional indirect light emission is provided, meaning that the components explained above for emitting light toward the top are omitted.

[0041] However, in this case too, the pressing element 40 is, of course, clamped between the light guide plate 10 or the reflector foil 20, if provided on the top side of the light guide plate 10, on the one hand, and a support element 90 provided on the top side of the housing, on the other hand, in order to ultimately press the light guide plate 10 toward the associated support element in accordance with the invention and thus position it correctly with respect to the light sources. This further example illustrates that, depending on the design of the luminaire 100, the support element 90 can be formed by various components. It is only necessary that the support element 90 is installed in the luminaire housing 110 with sufficient stability to ensure that the pressing element 40 is clamped in place.However, an exact positioning of the support element 90 is not absolutely necessary, since any tolerances are compensated by the flexibility of the pressure element 40.

[0042] Ultimately, the inventive solution contributes to ensuring optimized light output in luminaires that use “edge-lit” technology.

Claims

[1] Luminaire (100), comprising • a preferably elongated LED light source (50, 51) for generating a light, • a light guide plate (10), wherein the LED light source (50, 51) is arranged on an incident irradiation edge surface (12) of the light guide plate (10) such that the light generated by the LED light source (50, 51) is irradiated into the light guide plate (10) via the incident irradiation edge surface (12) and emitted via at least one flat side (11) of the light guide plate (10), • a support element for supporting the light guide plate (10), and • a pressing element (40) which is arranged between the light guide plate (10) and a support element (90) which is opposite the support element with respect to the light guide plate (10) and is designed to press the light guide plate (10) in the direction of the support element, characterized bythat the pressing element (40) forms at least one, preferably several spring elements (45) which extend from a flat base region (41) of the pressing element (40) and are supported on the supporting element (90) or a component arranged in front of the supporting element. [2] Luminaire according to claim 1, characterized by that the spring element(s) (45) are formed by fingers which extend in an arc from the flat base region (41) in the direction of the support element (90). [3] Luminaire according to claim 1 or 2, characterized by that the pressing element (40) is formed in one piece. [4] Luminaire according to one of the preceding claims, characterized by that the pressing element (40) is formed by a plastic part, preferably by an injection-molded plastic part. [5] Luminaire according to one of the preceding claims, characterized bythat the base region (41) rests flat on the light guide plate (10) or a reflector element (20) resting on the light guide plate (10). [6] Luminaire according to one of the preceding claims, characterized by that the support element (90) is formed by a heat sink element or another component which is arranged on a rear side of the lamp (100) and fastened there. [7] Luminaire according to one of the preceding claims, characterized by that it further comprises a support element (60) for holding the LED light source (50, 51). [8] Luminaire according to claim 7, characterized by that the carrier element (60) has a first web (61) on which the LED light source (50, 51) is arranged, and a second web (62) which is angled to the first web (61) and forms a support surface for the light guide plate (10). [9] Luminaire according to claim 7 or 8, characterized bythat the pressing element (40) has an end region (42) which engages in a positioning opening in the carrier element. [10] Luminaire according to claim 9, characterized by that the end region (42) of the pressing element (40) is deformable in a plane parallel to the light guide plate (10), wherein the end region (42) is preferably designed in a hook-like manner. [11] Luminaire according to one of the preceding claims, characterized by that the LED light source comprises an elongated circuit board (50) on which LEDs (51) are distributed, wherein the length of the circuit board (50) preferably corresponds to the length of the incident beam edge surface (12) of the light guide plate (10). [12] Luminaire according to one of the preceding claims, characterized bythat it has a housing (110) which forms a light exit opening (115), wherein a disc-like diffuser element (30) is preferably arranged in the region of the light exit opening (115), via which light is emitted by the luminaire (100). [13] Luminaire according to one of the preceding claims, characterized by that it is a floor lamp or a pendant lamp.

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