LED BACKLIGHTING SYSTEM

Abstract

LED backlighting system (10, 20) with a carrier (100), an optoelectronic semiconductor chip arrangement (200), a reflector (300) and a diffuser element (400), wherein the optoelectronic semiconductor chip arrangement (200) is arranged on a top side (101) of the carrier (100), wherein the reflector (300) has a through-opening (330) which extends between a lower opening (320) on a bottom side (302) of the reflector (300) and an upper opening (310) on a top side (301) of the reflector (300), wherein the reflector (300) is arranged on the top (101) of the carrier (100), wherein the underside (302) of the reflector (300) faces the top side (101) of the support (100), wherein the optoelectronic semiconductor chip arrangement (200) is arranged in the through-hole (330) of the reflector (300), wherein the diffuser element (400) has a top (401) and a bottom (402), wherein the diffuser element (400) is arranged above the top (301) of the reflector (300), wherein the underside (402) of the diffuser element (400) faces the top side (301) of the reflector (300), and wherein the underside (402) of the diffuser element (400) is designed as a free-form surface, wherein the diffuser element (400) has a central axis (440) defined by a center point (441) of the top (401) and a center point (442) of the bottom (402), wherein a thickness (445, 455, 465, 475, 485) of the diffuser element (400) measured between the bottom (402) of the diffuser element (400) and the top (401) of the diffuser element (400) parallel to the central axis (440) has different values ​​in different areas of the diffuser element (400), wherein the thickness (445, 465) of the diffuser element (400) has a greater value at a location (460) along a diagonal plane (430) than at the central axis (440) of the diffuser element (400).

Description

[0001] The present invention relates to an LED backlighting system.

[0002] Backlighting systems are known from the prior art and are used, for example, in liquid crystal displays. It is known to use LEDs as the light source in backlighting systems. It is also known to arrange the LEDs in such LED backlighting systems in a matrix.

[0003] One object of the present invention is to provide an LED backlighting system. This object is achieved by an LED backlighting system with the features of the independent claim. Various further developments are specified in the dependent claims.

[0004] The invention is defined by the claims.

[0005] LED backlighting systems are known from the publications DE 10 2016 122 770 A1, US 2016 / 0 005 931 A1, US 2006 / 0 208 269 A1, US 2008 / 0 315 228 A1, US 2012 / 0 068 615 A1, US 2008 / 0 315 227 A1, EP 1 467 417 A2, JP 2007- 281 260 A, US 2015 / 0 221 623 A1, US 2006 / 0 290 253 A1, US 2012 / 0 236 213 A1 and GB 2 544 895 A.

[0006] An LED backlight system comprises a substrate, an optoelectronic semiconductor chip array, a reflector, and a diffuser element. The optoelectronic semiconductor chip array is located on the top side of the substrate. The reflector has a through-hole extending between a lower opening on the underside of the reflector and an upper opening on the top side of the reflector. The reflector is located on the top side of the substrate, with its underside facing the top side of the substrate. The optoelectronic semiconductor chip array is located within the through-hole of the reflector. The diffuser element has a top and a bottom side. The diffuser element is positioned above the top side of the reflector such that its underside faces the top side of the reflector.

[0007] Advantageously, this LED backlighting system can be designed with a thin profile. The reflector and the diffuser element positioned above it ensure good homogeneity of the light emitted by the LED backlighting system and simultaneously guarantee minimal crosstalk between the unit cells of the LED backlighting system. This advantageously allows for local dimming of individual areas of the LED backlighting system.

[0008] In one embodiment of the LED backlighting system, the lower opening of the reflector has a circular disk shape, an elliptical shape, or a cushion shape. The lower opening of the reflector can be dimensioned such that there is only a small distance between the edge of the lower opening and the optoelectronic semiconductor chip array located within the reflector's opening. Advantageously, this results in only a small area of ​​the substrate's top surface remaining uncovered by the reflector in the vicinity of the optoelectronic semiconductor chip array. An asymmetrical shape of the lower opening of the reflector can achieve asymmetrical light emission from the reflector.

[0009] In one embodiment of the LED backlighting system, the upper opening of the reflector has a cushion or square shape with rounded corners. Advantageously, the cushion or square shape of the reflector's upper opening is well-suited for a matrix-like arrangement of multiple unit cells of the LED backlighting system. The reflector transforms the shape of the lower opening into the shape of the upper opening. The reflector can be designed such that its opening transitions smoothly from the lower opening to the upper opening without any sharp edges or kinks. This is further enhanced by the rounded corners of the upper opening.

[0010] In one embodiment of the LED backlighting system, the reflector has a rim on its upper surface that surrounds the top opening and at least one spacer arranged on this rim. The diffuser element rests against the spacer, creating an air gap between the rim of the reflector and the underside of the diffuser element. Advantageously, this air gap between the reflector and the diffuser element allows light emitted from the optoelectronic semiconductor chip array to pass laterally beyond the rim of the reflector, thus preventing shadowed areas between the unit cells of the LED backlighting system. The arrangement of the diffuser element on the spacer of the reflector advantageously provides a simple and reliable mechanical solution for the precise relative positioning of the reflector and the diffuser element.

[0011] In one embodiment of the LED backlighting system, the diffuser element has a central axis defined by the center point of the top and the center point of the bottom. The thickness of the diffuser element, measured parallel to this central axis between the bottom and top surfaces of the diffuser element, varies across different areas of the element. These varying thicknesses result in locally different diffuser effects. This locally varying diffuser effect can compensate for locally varying intensities of the light exiting the reflector's top opening, thereby achieving a high degree of homogeneity in the light emitted by the LED backlighting system.

[0012] In one embodiment of the LED backlighting system, the thickness of the diffuser element is smaller at a point along a side mid-plane than at the central axis of the diffuser element. Advantageously, this design of the diffuser element effectively homogenizes the light emitted by the LED backlighting system.

[0013] According to the invention, the thickness of the diffuser element is greater at a point along a diagonal plane than at a central axis of the diffuser element. Advantageously, this can compensate for particularly high luminance in the areas along the diagonal plane where the light exiting the upper opening of the reflector has a particularly high luminance.

[0014] According to the invention, the underside of the diffuser element is designed as a freeform surface. In this case, the locally varying thickness of the diffuser element is at least partially achieved through the design of the underside of the diffuser element.

[0015] According to the invention, the top surface of the diffuser element is designed as a flat surface. Advantageously, further components of the LED backlighting system, such as a stack of foils, can then be easily arranged on the top surface of the diffuser element. However, it is also possible to design the top surface of the diffuser element as a freeform surface in order to at least partially achieve the locally varying thickness of the diffuser element through its design. In this case, the underside of the diffuser element can optionally also be designed as a freeform surface or as a flat surface.

[0016] In one embodiment of the LED backlighting system, the diffuser element has the same symmetry as the reflector. For example, if the reflector has quadrant symmetry, then the diffuser element also has quadrant symmetry. Conversely, if the reflector has only mirror symmetry, then the diffuser element is also mirror-symmetric. Advantageously, such matching of the reflector and diffuser shapes results in particularly good homogenization of the light emitted by the LED backlighting system.

[0017] In one embodiment of the LED backlighting system, the underside of the diffuser element has a circumferential rim that rests against the top of the reflector. Advantageously, this results in a particularly simple and mechanically reliable arrangement of the diffuser element on the top of the reflector.

[0018] In one embodiment of the LED backlighting system, the diffuser element has embedded diffuser particles, in particular diffuser particles comprising Al2O3, TiO2, or SiO2. Advantageously, embedding such diffuser particles in the diffuser element has proven to be particularly effective.

[0019] In one embodiment of the LED backlighting system, the system features a stack of films arranged on the top of the diffuser element. This film stack can, for example, polarize the light emitted by the LED backlighting system. Furthermore, the film stack can be designed such that light not exhibiting the desired polarization direction is not lost but recycled. This allows the LED backlighting system to advantageously achieve a particularly high efficiency.

[0020] In one embodiment of the LED backlighting system, the optoelectronic semiconductor chip arrangement has a top surface, a bottom surface, and several side surfaces. The optoelectronic semiconductor chip arrangement is configured to emit at least 50% of the emitted light power from the side surfaces, preferably at least 80%. Advantageously, this results in a particularly high homogeneity of the light emitted by the LED backlighting system.

[0021] In one embodiment of the LED backlighting system, the optoelectronic semiconductor chip assembly comprises an optoelectronic semiconductor chip. The optoelectronic semiconductor chip is embedded in a wavelength-converting material that forms the side surfaces of the optoelectronic semiconductor chip assembly. A primary reflector is arranged on one top surface of the wavelength-converting material, forming the top surface of the optoelectronic semiconductor chip assembly. Advantageously, the primary reflector of this optoelectronic semiconductor chip assembly provides the desired high lateral emission of the optoelectronic semiconductor chip assembly.

[0022] In one embodiment of the LED backlighting system, the reflector forms a continuous reflector assembly with other identical reflectors. The diffuser element, together with other identical diffuser elements, forms a continuous diffuser assembly. A further identical optoelectronic semiconductor chip array is arranged in the aperture of each additional reflector. The LED backlighting system thus comprises a plurality of identically configured unit cells. These unit cells can, for example, be arranged in a regular matrix configuration. Advantageously, this allows the LED backlighting system to be scaled to the desired size and to emit light with good homogeneity across its entire surface.

[0023] The properties, features, and advantages of this invention described above, as well as the manner in which they are achieved, will become clearer and more readily understandable in connection with the following description of the exemplary embodiments, which are explained in more detail in conjunction with the drawings. These drawings show, in schematic form: Fig. 1 a cutaway side view of an initial LED backlighting system; Fig. 2 a cutaway side view of an optoelectronic semiconductor chip arrangement of the LED backlighting system; Fig. 3 a perspective view of a reflector of the LED backlighting system; Fig. 4 a representation of a wall of a through-opening of the reflector; Fig. 5 a view of a lower opening of the reflector; Fig. 6 a view of an upper opening of the reflector; Fig. 7 a perspective view of a first variant of a diffuser element of the LED backlighting system; Fig. 8 a first cut through this diffuser element; Fig. 9 a second cut through this diffuser element; Fig. 10 a perspective view of a second variant of the diffuser element; Fig. 11 a section through this diffuser element; Fig. 12 a perspective view of a third variant of the diffuser element; Fig. 13 a first cut through this diffuser element; Fig. 14 a second cut through this diffuser element; Fig. 15 a perspective view of a fourth variant of the diffuser element; Fig. 16 a first cut through this diffuser element; Fig. 17 a second cut through this diffuser element; Fig. 18 a perspective view of a reflector array; Fig. 19 a perspective view of a diffuser assembly; Fig. 20 a cutaway side view of a second variant of the LED backlighting system; Fig. 21 a perspective view of the reflector of the second variant of the LED backlighting system; and Fig. 22 a spacer on the reflector of the second variant of the LED backlighting system.

[0024] Fig. Figure 1 shows a schematic cutaway side view of part of an LED backlighting system 10. The LED backlighting system can be used, for example, for backlighting in a liquid crystal display or other liquid crystal display.

[0025] The schematic representation of the Fig. The part of the LED backlight system 10 shown in Figure 1 can be referred to as a unit cell of the LED backlight system 10. The LED backlight system 10 can comprise a plurality of such unit cells. The unit cells can be arranged in a regular matrix arrangement.

[0026] The LED backlighting system 10 has a carrier 100 with a top surface 101. The carrier 100 can, for example, be designed as a printed circuit board (PCB).

[0027] The LED backlighting system 10 further comprises an optoelectronic semiconductor chip arrangement 200. In Fig. Figure 1 shows a highly simplified representation of the optoelectronic semiconductor chip arrangement 200. Fig. Figure 2 shows a more detailed schematic cutaway side view of the optoelectronic semiconductor chip assembly 200.

[0028] The optoelectronic semiconductor chip arrangement 200 has an approximately cuboid basic shape with a top surface 201, a bottom surface 202 opposite the top surface 201 and several side surfaces 203 extending between the top surface 201 and the bottom surface 202.

[0029] The underside 202 of the optoelectronic semiconductor chip assembly 200 is formed by a conductor frame 220. The conductor frame 220 can have several electrically isolated sections, which in Fig. Figure 2 is shown only schematically. One underside of the conductor frame 220 forms the underside 202 of the optoelectronic semiconductor chip arrangement 200.

[0030] An optoelectronic semiconductor chip 210 is arranged on one upper surface of the conductor frame 220. The optoelectronic semiconductor chip 210 is electrically connected to the conductor frame sections of the conductor frame 220, for example via a bond connection, an electrically conductive adhesive connection, and / or bond wires. The optoelectronic semiconductor chip 210 is configured to emit electromagnetic radiation, for example, light of a blue, violet, ultraviolet, or other color. The optoelectronic semiconductor chip 210 can, for example, be configured as a light-emitting diode (LED) chip.

[0031] In the areas surrounding the optoelectronic semiconductor chip 210, a potting material 230 is arranged on the upper side of the conductor frame 220. The conductor frame 220 can be embedded in the potting material 230. It is advantageous if the potting material 230 has a high reflectivity. For example, the potting material 230 can be white. In a simplified embodiment, the potting material 230 can be omitted.

[0032] A wavelength-converting material 240 is arranged above the conductor frame 220 of the optoelectronic semiconductor chip assembly 200. The optoelectronic semiconductor chip 210 is embedded in the wavelength-converting material 240. The wavelength-converting material 240 forms the side surfaces 203 of the optoelectronic semiconductor chip assembly 200. The wavelength-converting material 240 is configured to convert at least some of the light emitted by the optoelectronic semiconductor chip 210 into light with a different wavelength. For example, the wavelength-converting material 240 can be configured to convert light emitted by the optoelectronic semiconductor chip 210 into white light. The wavelength-converting material 240 can comprise a matrix material and wavelength-converting particles embedded in the matrix material. The matrix material can be, for example, a silicone or an epoxy.

[0033] A primary reflector 250 is arranged above the wavelength-converting material 240, forming the top surface 201 of the optoelectronic semiconductor chip assembly 200. The primary reflector 250 is designed to reflect light emitted by the optoelectronic semiconductor chip 210 and converted in the wavelength-converting material 240, so that only a small portion of this light exits through the top surface 201 of the optoelectronic semiconductor chip assembly 200. A major portion of the light generated by the optoelectronic semiconductor chip assembly 200 exits through the side surface 203 of the optoelectronic semiconductor chip assembly 200. It is advantageous if at least 50% of the emitted light power is emitted from the side surfaces 203. It is particularly advantageous if at least 80% of the light power is emitted from the side surfaces 203.

[0034] In Fig. 1 can be seen that the LED backlighting system 10 comprises a reflector 300 with the basic shape of a cuboid and with a top 301 and a bottom 302 opposite the top. Fig. Figure 3 shows a schematic perspective representation of the reflector 300 without the other components of the LED backlighting system 10.

[0035] The reflector 300 has a through-opening 330 extending between the underside 302 and the top side 301. On the top side 301, the through-opening 330 has an upper opening 310. On the underside 302, the through-opening 330 has a lower opening 320. The through-opening 330 thus extends from the lower opening 320 located on the underside 302 to the upper opening 310 located on the top side 301. The upper opening 310 is larger than the lower opening 320, so that the through-opening 330 widens in a funnel shape from the lower opening 320 to the upper opening 310. The upper opening 310 is so large that only a narrow circumferential rim 340 remains on the top side 301 of the reflector 300. The upper opening 310 thus occupies almost the entire top surface 301 of the reflector 300.

[0036] A wall 331 of the opening 330 forms a reflective mirror surface. It is advantageous if the wall 331 has a high reflectivity, for example, a reflectivity of more than 80%. For this purpose, the reflector 300 can, for example, be made of a white material. It is advantageous if the wall 331 of the opening 330 of the reflector 300 exhibits Lambertsch scattering. A specular reflection component of up to 30% is advantageous.

[0037] Fig. Figure 5 shows a schematic top view of the lower opening 320 on the underside 302 of the reflector 300. Fig. Figure 6 shows a schematic top view of the upper opening 310 on the top 301 of the reflector 300. Fig. Figure 4 shows a schematic perspective representation of the wall 331 of the passage opening 330 of the reflector 300 extending between the lower opening 320 and the upper opening 310, without the other parts of the reflector.

[0038] The wall 331 of the through-opening 330 is designed such that the shape of the lower opening 320 is transformed into the shape of the upper opening 310 without the wall 331 having any sharp edges or kinks. Simultaneously, the wall 331 of the through-opening 330 is curved such that the void of the through-opening 330 of the reflector 300 has a convex shape. The wall 331 of the through-opening 330 is therefore concavely curved. For this purpose, the shape of the wall 331 can be modeled, for example, using guide curves.

[0039] The lower opening 320 points in the Fig. 3, Fig. 4, Fig. 5 to Fig. The example shown in Figure 6 has a circular disc shape. However, a cushion shape or an elliptical shape would also be possible. If the lower opening 320 has a cushion shape, then the corners of the lower opening 320 are expediently rounded and oriented towards the corners of the underside 302 of the reflector 300.

[0040] In the example shown in the figures, the upper opening 310 of the reflector 300 has a cushion shape with rounded corners 311. The rounded corners 311 of the cushion-shaped upper opening 310 are oriented towards the corners of the top surface 301 of the reflector 300. Alternatively, the upper opening 310 of the reflector 300 can have a square shape. In this case as well, it is advantageous for the corners of the upper opening 310 to be rounded so that the wall 331 of the through-opening 330 can be formed without sharp edges or kinks.

[0041] In the Fig. 3, Fig. 4, Fig. 5 to Fig. In the example shown, the top surface 301 and the bottom surface 302 of the reflector 300 are each square. The lower opening 320 and the upper opening 310 each have a quadrant-symmetrical shape. This means that the top surface 301 with the upper opening 310 and the bottom surface 302 with the lower opening 320 are each mirror-symmetrical with respect to reflections across the bisectors of the sides and also mirror-symmetrical with respect to reflections across the diagonals. Due to the quadrant-symmetrical design of the bottom surface 302 with the lower opening 320 and the top surface 301 with the upper opening 310, the through-opening 330 with the wall 331 is also quadrant-symmetrical. However, it is also possible, for example, to design the reflector 300 to be mirror-symmetrical only with respect to reflections across two mutually perpendicular planes.In this case, the lower opening 320 of the reflector 300 can, for example, have an elliptical shape. Other shapes and symmetries are also possible.

[0042] The top 301 and the bottom 302 of the reflector 300 can, for example, each have edge lengths of 12.5 mm. The lower opening 320 can, for example, have a diameter of 4.69 mm. The upper opening 310 can, for example, have a width of 12.26 mm. The cushion shape of the upper opening 310 can, for example, be such that the surrounding rim 240 has a maximum width of 0.33 mm. The rounded corners 311 of the upper opening 310 can have a radius of, for example, 0.23 mm.

[0043] As in Fig. As shown in Figure 1, the reflector 300 is arranged on the upper surface 101 of the carrier 100 such that the lower surface 302 of the reflector 300 faces the upper surface 101 of the carrier 100. The optoelectronic semiconductor chip arrangement 200 is arranged on the upper surface 101 of the carrier 100 such that the lower surface 202 of the optoelectronic semiconductor chip arrangement 200 faces the upper surface 101 of the carrier 100. The optoelectronic semiconductor chip arrangement 200 is located in the through-opening 330 of the reflector 300. It is advantageous if the lower opening 320 on the lower surface 302 of the reflector 300 is dimensioned such that only a small distance remains between the optoelectronic semiconductor chip arrangement 200 and the edge of the lower opening 320 of the reflector 300. This ensures that in the area below the lower opening 320 of the reflector 300 only a small part of the upper surface 101 of the support 100 is uncovered.

[0044] The LED backlighting system 10 further comprises a diffuser element 400 with a top surface 401 and a bottom surface 402 opposite the top surface 401. The diffuser element 400 is positioned above the top surface 301 of the reflector 300 such that the bottom surface 402 of the diffuser element 400 faces the top surface 301 of the reflector 300. The diffuser element 400 is thus positioned above the upper opening 310 of the reflector 300. The bottom surface 402 of the diffuser element 400 may have a circumferential rim 403 that rests on the circumferential rim 340 on the top surface 301 of the reflector 300.

[0045] The diffuser element 400 is designed to diffusely scatter light generated by the optoelectronic semiconductor chip arrangement 200 and exiting through the upper opening 310 of the reflector 300. For this purpose, the diffuser element 400 comprises a substantially transparent matrix material 410 and diffuser particles 415 embedded in the matrix material 410. The matrix material 410 can be, for example, PMMA, a polycarbonate, a silicone, or an epoxy. The diffuser particles 415 can be, for example, Al₂O₃, TiO₂, or SiO₂. Optionally, the diffuser element 400 can also include embedded wavelength-converting particles. The diffuser element 400 can be manufactured, for example, by an injection molding process.

[0046] Fig. Figure 7 shows a schematic perspective representation of a first variant of the diffuser element 400. In the example shown, the top surface 401 and the bottom surface 402 of the diffuser element 400 are square and have the same external dimensions as the top surface 301 and the bottom surface 302 of the reflector 300.

[0047] In Fig. Figure 7 shows the underside 402 of the diffuser element 400. The underside 402 is designed as a freeform surface and has a topography with ridges and depressions. The top side 401 of the diffuser element 400 is designed as a flat surface in the example shown. Alternatively, the top side 401 of the diffuser element 400 could be designed as a freeform surface with ridges and depressions. In this case, the underside 402 of the diffuser element 400 could be flat or also designed as a freeform surface.

[0048] In Fig. Figure 7 shows a central axis 440 of the diffuser element 400, which extends through a center point 441 of the top surface 401 and through a center point 442 of the bottom surface 402 of the diffuser element 400. Thus, the central axis 440 is oriented perpendicular to the flat top surface 401 of the diffuser element 400. Furthermore, in Fig. Figure 7 shows two diagonal planes 430, each extending through two opposite corners of the top surface 401 and two opposite corners of the bottom surface 402 of the diffuser element 400. Furthermore, two mid-side planes 420 are shown, each intersecting the outer surfaces of the diffuser element 400 centrally and perpendicularly. The diagonal planes 430 and the mid-side planes 420 all intersect at the central axis 440.

[0049] Since the underside 402 of the diffuser element 400 is designed as a freeform surface with elevations and depressions, the thickness of the diffuser element 400, measured between the underside 402 and the top side 401 parallel to the central axis 440, varies across different areas of the diffuser element 400. Thus, the diffuser element 400 is thicker in some places and thinner in others. This results in a locally varying optical path length within the diffuser element 400 and consequently a locally varying scattering effect. Light entering the diffuser element 400 in an area of ​​greater thickness is scattered more strongly than light entering the diffuser element 400 in an area of ​​lesser thickness.

[0050] The underside 402 of the diffuser element 400, designed as a freeform surface, is configured such that local luminance differences of the light exiting the upper opening 310 of the reflector 300 are at least partially compensated by the diffuser element 400. For this purpose, the diffuser element 400 has a greater thickness in areas of high luminance than in areas of lower luminance. Since the symmetry of the luminance distribution of the light exiting the reflector 300 at the upper opening 310 corresponds to the symmetry of the aperture 330 of the reflector 300, it is advantageous for the diffuser element 400 to have the same symmetry as the reflector 300.

[0051] Fig. Figure 8 shows a view cut at one of the side center planes 420 of the in Fig. 7 shown variant of the diffuser element 400. Fig. Figure 9 shows a view cut at one of the diagonal planes 430 of the in Fig. 7 shown variant of the diffuser element 400. In Fig. 8 and Fig. Figure 9 shows a thickness of 445 of the diffuser element 400 at the central axis 440 of the diffuser element 400. Furthermore, in Fig. Figure 8 shows a thickness 475 of the diffuser element 400 in a boundary region 470 of the diffuser element 400, in which the side mid-plane 420 intersects one of the outer sides of the diffuser element 400. Furthermore, in Fig. 8. A thickness 485 of the diffuser element 400 is shown at a point 480 located between the edge region 470 and the central axis 440 on the side center plane 420. Fig. Figure 9 shows a thickness of 455 in a corner area 450 of the diffuser element 400. Furthermore, in Fig. 9 a thickness 465 is drawn at a point 460 located between the corner area 450 and the central axis 440 on the diagonal plane 430.

[0052] The elevations and depressions of the underside 402, which is designed as a freeform surface, in Fig. 7, Fig. 8 to Fig. The nine variants of the diffuser element 400 shown are designed such that the thickness 485 at the point 480 on the side mid-plane 420, located between the edge region 470 and the central axis 440, is less than the thickness 445 at the central axis 440. The thickness 485 at this point 480 is also less than the thickness 475 in the edge region 470 of the diffuser element 400. The thickness 465 at the point 460 on the diagonal plane 430, located between the corner region 450 and the central axis 440, is greater than the thickness 445 at the central axis 440. The thickness 465 at this point 460 is also greater than the thickness 455 in the corner region 450 of the diffuser element 400.

[0053] Fig. Figure 10 shows a schematic perspective view of a second variant of the diffuser element 400. In this variant of the diffuser element 400, the underside 402 of the diffuser element 400, which is designed as a freeform surface, is shaped somewhat differently than in the one shown in Figure 1. Fig. 7, Fig. 8 to Fig. 9 shown first variant. Fig. Figure 11 shows a sectioned representation of the second variant of the diffuser element 400 at one of the side center planes 420.

[0054] In the second variant of the diffuser element 400, the underside 402 has a central elevation centered around the central axis 440, which is enclosed by an annular depression. This depression is in turn enclosed by a elevation adjacent to the corner regions 450 and the edge regions 470. Thus, even in the Fig. 10 and Fig. In the second variant of the diffuser element 400 shown in Figure 11, the thickness 485 at the point 480 located on the side mid-plane 420 between the edge region 470 and the central axis 440 is less than the thickness 445 at the central axis 440. The thickness 485 at this point 480 is also less than the thickness 475 in the edge region 470. Furthermore, in the second variant of the diffuser element 400, the thickness 465 at the point 460 located on the diagonal plane 430 between the corner region 450 and the central axis 440 is also greater than the thickness 445 at the central axis 440.

[0055] Fig. Figure 12 shows a schematic perspective representation of a third variant of the diffuser element 400. In the third variant of the diffuser element 400, the underside 402 of the diffuser element 400, designed as a freeform surface, has a different shape than in the first variant and the second variant of the diffuser element 400. Fig. Figure 13 shows a sectioned representation of the third variant of the diffuser element 400 at one of the side center planes 420. Fig. Figure 14 shows a representation of the third variant of the diffuser element 400, cut at one of the diagonal planes 430.

[0056] Fig. Figure 13 shows that, even in the third variant of the diffuser element 400, the thickness 485 at the point 480 located between the edge region 470 and the central axis 440 on the side center plane 420 is less than the thickness 445 at the central axis 440. Furthermore, the thickness 485 at this point 480 is also less than the thickness 475 of the diffuser element 400 in the edge region 470. Fig. Figure 14 shows that, even in the third variant of the diffuser element 400, the thickness 465 at the point 460 located between the corner region 450 and the central axis 440 on the diagonal plane 430 is greater than the thickness 445 at the central axis 440 of the diffuser element 400. The thickness 465 at this point 460 is also greater than the thickness 455 in the corner region 450 of the diffuser element 400.

[0057] Fig. Figure 15 shows a schematic perspective representation of a fourth variant of the diffuser element 400. In the fourth variant of the diffuser element 400, the underside 402 of the diffuser element 400, which is designed as a freeform surface, is designed differently than in the first, second and third variants of the diffuser element 400. Fig. Figure 16 shows a sectioned representation of the fourth variant of the diffuser element 400 at one of the side center planes 420. Fig. Figure 17 shows a representation of the fourth variant of the diffuser element 400, cut at one of the diagonal planes 430.

[0058] Fig. Figure 16 shows that, even in the fourth variant of the diffuser element 400, the thickness 485 at the point 480 located between the edge region 470 and the central axis 440 on the side center plane 420 is less than the thickness 445 at the central axis 440. Furthermore, the thickness 485 at this point 480 is also less than the thickness 475 in the edge region 470 of the diffuser element 400. Fig. Figure 17 shows that, even in the fourth variant of the diffuser element 400, the thickness 465 at the point 460 located between the corner region 450 and the central axis 440 is greater than the thickness 445 at the central axis 440 of the diffuser element 400. Furthermore, the thickness 465 at this point 460 is greater than the thickness 455 in the corner region 450 of the diffuser element 400.

[0059] Of course, other configurations of the diffuser element 400 are also possible.

[0060] Fig. Figure 1 shows that the LED backlighting system 10 has a film stack 600 arranged on the top surface 401 of the diffuser element 400. The film stack 600 can comprise one or more films, which may, for example, be designed to polarize the light emitted by the LED backlighting system 10. The films of the film stack 600 can be configured such that light not exhibiting the desired polarization direction is reflected and recycled within the film stack 600. The films of the film stack 600 can, for example, be configured as a Brightness Enhancement Film (BEF) and / or as a Dual Brightness Enhancement Film (DBEF).

[0061] Fig. Figure 18 shows a schematic perspective view of a reflector assembly 360. The reflector assembly 360 comprises a plurality of reflectors 300, each configured as shown above. Fig. 3, Fig. 4, Fig. 5 to Fig. 6 described. The reflectors in the 360° reflector assembly are arranged in a regular matrix pattern and are integrally connected to one another. In the Fig. The example shown in Figure 18 comprises the reflector array 360 8×8 reflectors 300. However, the reflector array 360 can also be configured with a different number of reflectors 300.

[0062] Fig. Figure 19 shows a schematic perspective view of a diffuser assembly 490. The diffuser assembly 490 comprises a plurality of diffuser elements 400, each configured as shown above. Fig. 7, Fig. 8, Fig. 9, Fig. 10, Fig. 11, Fig. 12, Fig. 13, Fig. 14, Fig. 15, Fig. 16 to Fig. 17 described. The individual diffuser elements 400 are arranged integrally in a regular matrix arrangement within the diffuser assembly 490. In the Fig. The example shown in 19 comprises the diffuser assembly 490 8×8 diffuser elements 400. However, a different number of diffuser elements 400 is also possible.

[0063] The LED backlighting system 10 can be used with a majority of the in Fig. The unit cells shown in 1 are formed. For this purpose, the Fig. 18 shown reflector array 360 and the one in Fig. The diffuser assembly 490 shown in Figure 19 is used. An optoelectronic semiconductor chip arrangement 200 is positioned in the through-hole 330 of each reflector 300 of the reflector assembly 360. The carrier 100 and the film stack 600 each have a size adapted to the size of the reflector assembly 360 and the diffuser assembly 490, respectively. By changing the number of unit cells of the LED backlight system 10, the size of the LED backlight system 10 can be scaled to a desired size.

[0064] Fig. Figure 20 shows a schematic cutaway side view of an LED backlighting system 20 according to a second variant. Fig. Figure 20 shows only one unit cell of the LED backlighting system 20. However, the LED backlighting system 20 can incorporate several of the elements shown in Fig. 20 unit cells are shown, which in this case can be arranged in a matrix-like manner.

[0065] The LED backlighting system 20 of the Fig. 20 shows a high degree of similarity with the LED backlighting system 10 of the Fig. 1. Corresponding components are in Fig. 20 with the same reference numerals as in Fig. 1. The following merely describes what distinguishes the LED backlighting system 20 of the Fig. 20 of the LED backlighting system 10 of the Fig. 1. Furthermore, the above description of the LED backlighting system 10 also applies to the LED backlighting system 20.

[0066] Fig. Figure 21 shows a schematic perspective representation of the reflector 300 of the LED backlighting system 20. Fig. Figure 22 shows a section of the reflector assembly 360, wherein the reflectors 300 are each designed like the reflector 300 of the LED backlighting system 20.

[0067] For example, the lower opening 310 of the reflector 300 of the LED backlighting system 20 can have a diameter of 3.59 mm. The upper opening 310 can have a width of 8.45 mm. The cushion shape of the upper opening 310 can be designed such that the surrounding rim 340 has a maximum width of 0.18 mm. Thus, the edge length of the reflector 300 can be 8.7 mm. The rounded corners 311 of the upper opening 310 of the reflector 300 can be rounded with a radius of, for example, 0.6 mm.

[0068] In Fig. Figure 22 shows that at each intersection point of four reflectors 300 of the reflector assembly 360, a spacer 350 is arranged on the circumferential edge 340 on the upper surface 301 of the reflectors 300. Thus, for each individual reflector 300, a spacer 350 is arranged on the circumferential edge 340 at each corner of the upper surface 301, as shown in Figure 22. Fig. 21 is recognizable. The spacers can each, for example, have a height of 0.2 mm above the other sections of the circumferential edge 340. The thickness of the reflector 300, measured from the underside 302 to the tip of the spacers 350, can, for example, be 2.69 mm.

[0069] Fig. Figure 20 shows that the diffuser element 400 in the LED backlighting system 20 is positioned above the top surface 301 of the reflector 300 such that the diffuser element 400 rests against the spacers 350. This results in an air gap 500 between the circumferential edge 340 of the reflector 300 and the underside 402 of the diffuser element 400 in the LED backlighting system 20. The thickness 510 of this air gap 500 corresponds to the height of the spacers 350 and can therefore be, for example, 0.2 mm.

[0070] The diffuser element 400 is part of the LED backlighting system 20. Fig.The diffuser element 400 of the LED backlighting system 20 is designed as a plane-parallel plate. Therefore, both the top surface 401 and the bottom surface 402 of the diffuser element 400 of the LED backlighting system 20 are designed as a flat surface. Thus, the diffuser element 400 of the LED backlighting system 20 has a constant thickness 446 in all sections. The constant thickness 446 of the diffuser element 400 can, for example, be 1.28 mm.

[0071] Furthermore, the diffuser element 400 of the LED backlighting system 20 can be configured like the diffuser element 400 of the LED backlighting system 10. It has proven particularly advantageous if the matrix material 410 of the diffuser element 400 of the LED backlighting system 20 comprises PMMA and the diffuser particles 415 are configured as Al₂O₃ particles. A proportion of 0.25 wt% of the diffuser particles 415 is advantageous. A suitable particle size for the diffuser particles 415 is 0.5 µm.

[0072] The air gap 500 of the LED backlighting system 20 formed between the circumferential edge 340 of the reflector 300 and the underside 402 of the diffuser element 400 advantageously allows light exiting the reflector 300 at the upper opening 310 to enter the area above the circumferential edge 340 of the reflector 300.

[0073] In another variant of the LED backlighting system 20, the diffuser element 400 can be designed as in the LED backlighting system 10 and have a different thickness in different sections of the diffuser element 400. REFERENCE MARK LIST 10 LED backlighting system 20 LED backlighting system 100 carriers 101 Top 200 optoelectronic semiconductor chip array 201 Top 202 Subpage 203 side surface 210 optoelectronic semiconductor chip 220 ladder frames 230 potting compound 240 wavelength-converting material 250 Primary reflector 300 reflector 301 Top 302 Underside 310 upper opening 311 rounded corners 320 lower opening 330 Through opening 331 Wall 340 surrounding border 350 spacers 360° reflector array 400 diffuser elements 401 Top 402 Underside 403 surrounding border 410 matrix material 415 diffuser particles 420 Page center level 430 Diagonal plane 440 Center axle 441 Center of the top 442 Center of the underside 445 Thickness at center axis 446 constant thickness 450 corner area 455 thickness in the corner area 460th place on the diagonal plane 465 thickness at the diagonal plane 470 Edge area 475 thickness at the edge 480 digits at page center level 485 thickness instead of on side center plane 490 Diffuser assembly 500 air gap 510 Thickness of the air gap 600 stacks of foil

Claims

[1] LED backlighting system (10, 20) comprising a carrier (100), an optoelectronic semiconductor chip arrangement (200), a reflector (300) and a diffuser element (400), wherein the optoelectronic semiconductor chip arrangement (200) is arranged on a top side (101) of the carrier (100), wherein the reflector (300) has a through-opening (330) which extends between a lower opening (320) on a bottom side (302) of the reflector (300) and an upper opening (310) on a top side (301) of the reflector (300), wherein the reflector (300) is arranged on the top (101) of the carrier (100), wherein the underside (302) of the reflector (300) faces the top side (101) of the support (100), wherein the optoelectronic semiconductor chip arrangement (200) is arranged in the through-hole (330) of the reflector (300), wherein the diffuser element (400) has a top (401) and a bottom (402), wherein the diffuser element (400) is arranged above the top (301) of the reflector (300), wherein the underside (402) of the diffuser element (400) faces the top side (301) of the reflector (300), and wherein the underside (402) of the diffuser element (400) is designed as a free-form surface, wherein the diffuser element (400) has a central axis (440) defined by a center point (441) of the top (401) and a center point (442) of the bottom (402), wherein a thickness (445, 455, 465, 475, 485) of the diffuser element (400) measured between the bottom (402) of the diffuser element (400) and the top (401) of the diffuser element (400) parallel to the central axis (440) has different values ​​in different areas of the diffuser element (400), wherein the thickness (445, 465) of the diffuser element (400) has a greater value at a location (460) along a diagonal plane (430) than at the central axis (440) of the diffuser element (400). [2] LED backlighting system (10, 20) according to claim 1, wherein the lower opening (320) of the reflector (300) has a circular disk shape, an elliptical shape or a cushion shape. [3] LED backlighting system (10, 20) according to one of the preceding claims, wherein the upper opening (310) of the reflector (300) has a cushion shape or a square shape, wherein the upper opening (310) has rounded corners (311). [4] LED backlighting system (20) according to any one of the preceding claims, wherein the reflector (300) has on its upper side (301) a rim (340) surrounding the upper opening (310) and at least one spacer (350) arranged on the surrounding rim (340), wherein the diffuser element (400) rests against the spacer (350), so that an air gap (500) is created between the circumferential edge (340) of the reflector (300) and the underside (402) of the diffuser element (400). [5] LED backlighting system (10) according to claim 1, wherein the thickness (445, 485) of the diffuser element (400) at a location (480) along a side center plane (420) is smaller than at the center axis (440) of the diffuser element (400). [6] LED backlighting system (10, 20) according to one of the preceding claims, wherein the top surface (401) of the diffuser element (400) is designed as a flat surface. [7] LED backlighting system (10, 20) according to one of the preceding claims, wherein the diffuser element (400) has the same symmetry as the reflector (300). [8] LED backlighting system (10, 20) according to one of the preceding claims, wherein the underside (402) of the diffuser element (400) has a circumferential rim (403) which rests on the top side (301) of the reflector (300). [9] LED backlighting system (10, 20) according to one of the preceding claims, wherein the diffuser element (400) has embedded diffuser particles (415), in particular diffuser particles (415) comprising Al2O3, TiO2 or SiO2. [10] LED backlighting system (10, 20) according to one of the preceding claims, wherein the LED backlighting system (10, 20) has a stack of foils (600) arranged on the top (401) of the diffuser element (400). [11] LED backlighting system (10, 20) according to one of the preceding claims, wherein the optoelectronic semiconductor chip arrangement (200) has a top surface (201), a bottom surface (202) and several side surfaces (203), wherein the optoelectronic semiconductor chip arrangement (200) is configured to emit at least fifty percent of the emitted light power at the side surfaces (203), preferably at least eighty percent. [12] LED backlighting system (10, 20) according to claim 11, wherein the optoelectronic semiconductor chip arrangement (200) comprises an optoelectronic semiconductor chip (210), wherein the optoelectronic semiconductor chip (210) is embedded in a wavelength-converting material (240) which forms the side surfaces (203) of the optoelectronic semiconductor chip arrangement (200), wherein a primary reflector (250) is arranged on a top side of the wavelength-converting material (240), which forms the top side (201) of the optoelectronic semiconductor chip arrangement (200). [13] LED backlighting system (10, 20) according to a the preceding claims, wherein the reflector (300) forms a connected reflector assembly (360) with similar additional reflectors (300), wherein the diffuser element (400) together with similar further diffuser elements (400) forms a connected diffuser assembly (490), wherein a further similar optoelectronic semiconductor chip arrangement (200) is arranged in the through-hole (330) of each further reflector (300).

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