DE102008033385A1 - Lighting device for use in series of two different lighting devices, particularly backlighting device, comprises laminar light source, optical element, particularly diffusion element, light entrance surface, and light emitting surface - Google Patents

Abstract

The lighting device comprises a laminar light source (2), an optical element, particularly a diffusion element (3), a light entrance surface, and a light emitting surface. The wall surface (7) is inclined to the laminar light source in relation to a level provided perpendicular (A). The wall surface is inclined outward. The laminar light source comprises two light sources (2b), particularly multiple light sources.

Description

Technical area

The The invention relates to a lighting device, in particular a backlighting device at least one planar light source, at least one optical element, preferably a diffusion element, with at least one light entry surface and at least one light exit surface, as well at least one side of the sheet-like light source and the optical element arranged, preferably the planar light source and the optical element laterally delimiting wall surface.

The The invention also relates to a series of at least two different ones Lighting devices, in particular backlighting devices, each comprising at least one planar light source, respectively at least one optical element, preferably a diffusion element, with at least one light entry surface and at least one Light-emitting surface and in each case at least one laterally of the planar light source and the arranged optical element, preferably the sheet-like light source and the optical element laterally delimiting wall surface.

State of the art

at Many lighting devices try to reduce the radiation the lighting device as evenly as possible, d. H. all Light radiating areas of the device appear when viewed from the main illumination direction approximately the same light. This serves In addition, a radiated by the radiated light area as possible to lighten evenly.

at Backlighting devices, for example for displays or labeling and billboards, it is also necessary to have an area, for example to illuminate a screen, a scoreboard or a logo evenly, to ensure good visibility and readability.

at other applications will try one at the periphery of the Light-emitting surface sloping illuminance to achieve one as possible gentle transition to reach an unlit area.

A large area radiating Lighting device consists for this reason mostly from a planar light source, d. H. a light source whose dimensions are perpendicular to the main emission are much larger as parallel to the main emission direction, and arranged in front of it optical element, in particular a diffusion element, in the interaction the desired one To cause radiation behavior. To an undesirable To prevent lateral light leakage are between sheet light source and optical element wall surfaces arranged. These wall surfaces are arranged parallel to a vertical on the surface light source, so that optical element and area light source almost the have the same footprint.

Flat-shaped light sources can while surface radiators such as organic light-emitting diodes or flat-building Fluorescent lamps formed with dielectric barrier discharge but it is also possible punctiform or linear Emitter, for example light-emitting diodes or discharge lamps, in particular Cold cathode tubes, to arrange so that this an approximately uniform radiation behavior , wherein by the use of a diffusion element as optical element then the desired high Degree of uniformity the radiation is ensured.

such Area lights are based on their dimensions and the arrangement of the individual Spotlights on their radiation behavior as well as the desired Size of the lighting device and thus the optical element.

adversely However, it is that the dimensions of conventional surface light sources are not or only with big Effort can be varied. these can for example, given by the dimensions of the discharge tubes used be or by a given pitch of the used Light-emitting diodes, usually specified by the requirements for the uniformity of the illumination is.

Thereby is the size of the optical Elements and thus also the beam exit surface of the lighting device set in relatively fixed increments. Should intermediate sizes be realized can not resort to existing surface light sources which reduces the cost of manufacturing and warehousing increased in the production of lighting devices. This even more so if a manufacturer manufactures a series of lighting fixtures wants to offer, d. H. a variety of different lighting devices, which are essentially the same or identical in structure differ in the size of the light exit surface.

Presentation of the invention

The object of the present invention is therefore to provide a lighting device, in particular dere a backlighting device comprising at least one planar light source, at least one optical element, preferably a diffusion element, with at least one light entry surface and at least one light exit surface and at least one planar light source and the optical element laterally delimiting wall surface to create at the size of the light exit surface is much less dependent on the size of the surface-shaped light source as in lighting devices according to the prior art.

Farther It is an object of the present invention to provide a series of at least two different lighting devices, in particular of Backlight devices, each comprising at least one planar light source, respectively at least one optical element, preferably a diffusion element, with at least one light entry surface and at least one light exit surface as well in each case at least one of the one planar light source and the optical element laterally delimiting wall surface to create, at the expense of making the series like also for the storage of the components needed to make the series is reduced.

These Task is relative the lighting device solved by the characterizing features of claim 1.

Regarding the Series of lighting fixtures will solve the problem the characterizing features of claim 10.

Especially advantageous embodiments can be found in the dependent claims.

By doing in a lighting device according to the preamble of the claim 1 the wall surface across from a perpendicular to a given by the sheet-like light source Plane is inclined, the size of the optical Elements and thus the light exit surface of the size of the surface-shaped light source chosen differently become. As by the sheet-like light source Given level is thereby considered a level for which the Average value of the distance of the planar light source forming Lighting elements of this level is practically zero. In the usual, plan planar light sources this level is obvious, however, are also surface radiators conceivable, for example, have the form of a ball cap or consist of mutually inclined individual elements.

The Lighting device can thus simplify the requirements be adjusted, since only the size of the optical Elements and the shape of the wall surfaces must be varied if a different size of the light exit surface is needed.

In addition, the planar light source and the optical element have different shapes and yet by means of the wall surface be connected because of the differences in shape by suitable inclination the wall surfaces between the light source and optical element can be compensated.

It can furthermore different when using a uniform planar light source optical elements are used, so not a variety different surface-shaped light sources must be kept if different lighting devices to be produced.

It is particularly advantageous if the wall surface is inclined outwards. This can do that optical element greater than the sheet-like light source accomplished become. Since the effort to produce sheet-like light sources with the Size increases, it is advantageous if for the largest possible optical Element one possible small areal light source can be used.

Conveniently, has the sheet-like light source at least two light sources, preferably a plurality of light sources on. The most common Illuminating elements that make up surface-shaped light sources are constructed are point or line sources, such as light emitting diodes (LED) or discharge lamps. To an area that is a much larger extension owns as a single spotlight, to illuminate evenly, thus become several emitters arranged in a meaningful arrangement, with the same luminosity usually equidistant. If these are line emitters, they usually become parallel Arrangement chosen, while Spot radiators are preferably to be arranged in a lattice form, for which principle each of the 5 Bravaisnets is suitable, but rectangular or hexagonal Networks are particularly suitable.

The Using a hexagonal arrangement has the advantage that the height of Light box can be very small, since the LEDs at the same occupation density have a smaller distance than in a rectangular arrangement and the height the lightbox is dependent on the distance of the LEDs. The rectangular arrangement has the advantage that results in a very simple structure.

It is particularly advantageous if the planar light source comprises at least one LED module, wherein the LED module preferably comprises a group of at least two LEDs, in particular of at least three LEDs. LEDs eige Especially for lighting purposes, since they have a long life and low power consumption. This is particularly advantageous for backlighting devices, as they are often mounted in poorly accessible locations and have long operating times. Furthermore, the low heat radiation of LED is advantageous, since so the optical element as well as other elements located in the beam path are thermally only slightly loaded. LED modules, ie the arrangement of LED and other components, such as drivers or heat sinks, on a support, can be advantageously combined to form a sheet-like light source or can represent a planar light source when a plurality of LEDs on a module itself.

advantageously, corresponds to the distance of the sheet-like light source from the optical element approximates the distance between two lighting elements from each other. This will be a particularly uniform illumination achieved the optical element. For lighting devices with Particularly high luminance sit the lighting elements very close together, which allows a very low height.

It has proven to be advantageous if the angle of inclination γ of the wall surface with respect to the vertical between 30 ° and 60 °. With an inclination in said region will cause a sufficient enlargement of the area of the optical element and / or reduction of the area of the planar light source in comparison with a lighting device according to the prior Technology achieved.

Especially an inclination angle γ between 40 and 50 ° is advantageous here a sufficient enlargement of the area of the optical element and / or reduction of the area of the planar light source achieved on the other hand, a uniform illumination in the edge area is ensured. This is especially true when as lighting elements Lambertian emitters, as these are light emitting diodes, are used and at a distance of the sheet-like light source of the optical element according to claim 5th

By doing the slope of the wall surface across from the vertical between 55 ° and 75 ° is, is a very big one Difference of the extent of sheet light source and optical element realizable. So this angle range is particularly interesting, if minor Loss of the Brightness towards the edge area is not disturbing or even desirable, for example, a smooth transition between illuminated and non-illuminated surfaces.

Especially advantageous is an inclination of the wall surface relative to the vertical between 60 ° and 70 °, because here on the one hand, there is a big one Difference of the extent of surface light source and optical Element and on the other hand, a sufficiently good homogeneity in the edge region.

By the use of further optical elements between sheet-like light source and optical element, it is possible the homogeneity to improve the edge area. These other optical elements can in particular directly on the sheet-like light source and / or arranged on individual luminous elements of the planar light source be. Be used as light emitting elements LEDs, the formed further optical elements, for example as lenses be that change the beam angle of the LEDs. By using Lens that increase the beam angle, the homogeneity in the edge area to be enlarged while Lenses that reduce the beam angle, the homogeneity in the edge area reduce.

Also Are angles greater than 75 ° conceivable, but then the marginal areas only very weak or not lit anymore.

By doing the wall surface surrounding the light source and / or the optical element on all sides, On the one hand, a lateral loss of light is avoided and on the other hand a very big one Area difference between optical element and sheet-like light source feasible, because the optical element then, for example, on all sides of the light source can protrude. Here are the shape of the base of the Light source and the optical element no limits, in particular can rectangular, oval, three-hexagonal and octagonal shapes with the special ones Formations of the square, the circle, and the ellipse as well as the equilateral Mehrecke be realized. The sheet-like light source and / or the optical element, however, in particular for construction of display backlights due to the prevailing rectangular Display design preferably have a rectangular base.

By doing the wall surface as part of a housing the lighting device is formed, a particular achieved a simple structure.

By the planar light source has a location-dependent, in particular to at least one edge region towards increasing luminance distribution, the luminance distribution can be adapted to the requirements of different applications. By the luminance to the Edge increases, for example, there by using brighter LED or be reduced by suitable control, the LEDs in the middle of the light source in their performance, a uniform illumination is achieved even at large angles of inclination of the wall surface.

Regarding The series of lighting devices, it is particularly advantageous if in at least one lighting device of the series, the wall surface opposite to a Perpendicular to a plane given by the planar light source outward is inclined. Thereby can using an identical planar light source at least two different geometries for the optical element and so that, for example, realized two different sizes for an illuminated area become. This is especially true in the backlighting of displays of advantage, since here only one size for the light source needed is to realize a variety of different screen sizes. The elaborate Process of designing a planar light source falls thus only once and also the warehousing in the production becomes simplified because only one sheet-like light source for the production of the series stockpiled and made available in production, too if the series has multiple lighting devices with different huge includes optical elements.

there it is advantageous if at least one lighting device the series all wall surfaces parallel to a perpendicular to a plane given by the planar light source are arranged. This design is particularly simple and can be quasi serve as the basic form of the series, of which the variants with others can be derived from optical elements.

Farther it is useful if in at least one lighting device of the series, the wall surface opposite one Perpendicular to a plane given by the planar light source outward is inclined. As a result, in this lighting device, the optical element greater than the sheet-like light source be executed.

It is also appropriate if at least one of the lighting devices according to a the claims 1 to 10 is formed. The advantages mentioned in these claims come especially good in a series of lighting devices to carry.

Brief description of the drawings

in the Below, the invention will be explained in more detail with reference to an embodiment. The Figures show:

1 A backlighting device in side sectional view as an example of a lighting device according to the prior art,

2 a backlight device according to the invention in a side sectional view.

Preferred embodiment of invention

In 1 is an example of a lighting device 1 According to the prior art, a backlighting device 1 shown. Such a lighting device 1 may also be part of a series of lighting devices according to the invention.

The backlighting device 1 consists essentially of a sheet-like light source 2 , which in the present embodiment as an LED module 2 is executed, as a diffuser 3 executed optical element 3 as well as a housing 4 that is made up of wraparound walls 5 and a bottom plate 6 is formed. The backlighting device 1 has a rectangular basic shape and serves as a backlight of a display device.

The wall surfaces 7 the walls 5 are parallel to a vertical A to the level of the LED module 2 aligned so that the diffuser 3 the same extent as the LED module 2 ,

The LED module 2 consists of a carrier 2a and a plurality of light-emitting diodes (LEDs) 2 B , which are arranged in the form of a square grid, wherein the distance of the grid points and thus the LEDs 2 B approximately the distance between the LED module 2 and the light entry surface 8th of the diffuser 3 equivalent. This will ensure that on the light exit surface 9 a homogeneous brightness distribution is achieved.

2 shows a backlighting device according to the invention 10 in a side sectional view. The LED module 2 is identical to the one in 1 shown while the diffuser 3 by a distance L to each side, ie also perpendicular to the plane, is extended. The wall surfaces 7 are thus opposite the vertical A to the LED module 2 tilted outwardly at an angle γ of approximately 45 °.

The wall surfaces 7 are with a foil 11 coated, by which the incident radiation is diffusely reflected. A similar film 12 is also used to coat the LED module 2 used and is known in the art.

With the arrangement shown, a uniform illumination is also within the Au Sections B ensured. Thus, using the identical LED module 2 a series of two different backlighting devices 1 getting produced.

Of course, other embodiments of the invention are conceivable. For example, the wall surfaces 7 also provided as separate components and not part of a housing 4 be. Also, a continuous film 11 on the wall surfaces 7 and the LED module 2 be applied, but these must be connected to each other before applying. Instead of the diffuser 3 which is typical for backlighting devices 1 is used, other optical elements are conceivable such as lens arrays.

Instead of the arrangement of the LEDs 2 B in the form of a square lattice, another shape, for example a hexagonal lattice, may be chosen, as well as a single LED module 2 It is also possible to use a plurality of LED modules, which are then likewise expediently arranged in such a way that a uniform illumination is achieved.

Also, instead of a rectangular shape of the lighting device 11 any other shape conceivable, for example, circular, hexagonal or octagonal lighting devices 11 , The angle of inclination γ of the wall surfaces 7 does not have to be on all sides of the lighting device 11 be identical and may even be from place to place over the perimeter of the sheet light source 2 vary. The inclination angle γ may also be over the wall surface 7 vary.

If a large inclination angle γ is selected, the illuminance increases to the edge of the light exit surface 9 down, but in some applications, such as the backlighting of an LC display, tolerated within certain limits, or even if a smooth transition of the brightness level is desired to the environment, even required.

Instead of the LED module 2 Other surface light sources come into question. These may be one-piece ("real") surface radiators, for example organic light-emitting diodes or planar fluorescent lamps with dielectric barrier discharge, as are manufactured and sold under the name "Planon" by OSRASM GmbH. Precisely with these lamps, only a few standard sizes are available due to the complex production, so that an adaptation to other sizes of the optical element is particularly advantageous.

Claims (14)

Lighting device ( 10 ), in particular backlight device ( 10 ) comprising at least one planar light source ( 2 ), at least one optical element ( 3 ), preferably a diffusion element ( 3 ), with at least one light entry surface ( 8th ) and with at least one light exit surface ( 9 ), as well as at least one laterally of the sheet-like light source ( 2 ) and the optical element ( 3 ), preferably the sheet-like light source ( 2 ) and the optical element ( 3 ) laterally delimiting wall surface ( 7 ), characterized in that the wall surface ( 7 ) with respect to a vertical (A) to a through the sheet-like light source ( 2 ) given plane is inclined. Lighting device ( 10 ) according to claim 1, characterized in that wall surface ( 7 ) is inclined outwards. Lighting device ( 10 ) according to claim 1 or 2, characterized in that the sheet-like light source ( 2 ) at least two light sources ( 2 B ), preferably a plurality of light sources ( 2 B ) having. Lighting device ( 10 ) according to one of claims 1 to 3, characterized in that the sheet-like light source ( 2 ) at least one LED module ( 2 ), wherein the LED module ( 2 ) preferably a group of at least two LEDs ( 2 B ), in particular of at least three LEDs ( 2 B ). Lighting device ( 10 ) according to one of claims 3 or 4, characterized in that the distance of the planar light source ( 2 ) of the optical element ( 3 ) approximately the distance between two light elements ( 2 B ) corresponds to each other. Lighting device ( 10 ) according to one of claims 1 to 5, characterized in that the inclination angle γ of the wall surface ( 7 ) is perpendicular to the vertical between 30 ° and 60 °, preferably between 40 ° and 50 °. Lighting device ( 10 ) according to one of claims 1 to 6, characterized in that the inclination of the wall surface relative to the vertical between 55 ° and 75 °, preferably between 60 ° and 70 °. Lighting device ( 10 ) according to one of claims 1 to 7, characterized in that the wall surface ( 7 ) the sheet-like light source ( 2 ) and / or the optical element ( 3 ) surrounds all sides. Lighting device ( 10 ) according to one of claims 1 to 8, characterized in that the Wall surface ( 7 ) as part of a housing ( 4 ) of the lighting device ( 10 ) is trained. Lighting device ( 10 ) according to one of claims 1 to 9, characterized in that the sheet-like light source ( 2 ) has a location-dependent, in particular to at least one edge region towards increasing luminance distribution. Series of at least two different lighting devices ( 1 . 10 ), in particular backlighting devices ( 1 . 10 ), each comprising at least one planar light source ( 2 ), at least one optical element ( 3 ), preferably a diffusion element ( 3 ) with at least one light entry surface ( 8th ) and at least one light exit surface ( 9 ) and in each case at least one laterally of the planar light source ( 2 ) and the optical element ( 3 ), preferably the sheet-like light source ( 2 ) and the optical element ( 3 ) laterally delimiting wall surface ( 7 ), characterized in that in at least one lighting device ( 10 ) of the series the wall surface ( 7 ) with respect to a vertical (A) to a through the sheet-like light source ( 2 ) given plane is inclined. Series of lighting devices ( 1 . 10 ) according to claim 11, characterized in that in at least one lighting device ( 1 ) of the series all wall surfaces ( 7 ) parallel to a vertical (A) to a through the surface-shaped light source ( 2 ) are arranged level. Series of lighting devices ( 1 . 10 ) according to claim 11 or 12, characterized in that in at least one lighting device ( 10 ) of the series the wall surface ( 7 ) with respect to a vertical (A) to a through the sheet-like light source ( 2 ) given plane is inclined outwards. Series of lighting devices ( 1 . 10 ) according to one of claims 11 to 13, characterized in that at least one of the lighting devices ( 10 ) is formed according to one of claims 1 to 10.