Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21K—NON-ELECTRIC LIGHT SOURCES USING LUMINESCENCE; LIGHT SOURCES USING ELECTROCHEMILUMINESCENCE; LIGHT SOURCES USING CHARGES OF COMBUSTIBLE MATERIAL; LIGHT SOURCES USING SEMICONDUCTOR DEVICES AS LIGHT-GENERATING ELEMENTS; LIGHT SOURCES NOT OTHERWISE PROVIDED FOR
  • F21K9/00—Light sources using semiconductor devices as light-generating elements, e.g. using light-emitting diodes [LED] or lasers
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
  • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
  • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
  • G02F1/1333—Constructional arrangements; Manufacturing methods
  • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
  • G02F1/1336—Illuminating devices
  • G02F1/133602—Direct backlight
  • G02F1/133603—Direct backlight with LEDs
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
  • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
  • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
  • G02F1/1333—Constructional arrangements; Manufacturing methods
  • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
  • G02F1/1336—Illuminating devices
  • G02F1/133602—Direct backlight
  • G02F1/133611—Direct backlight including means for improving the brightness uniformity
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
  • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
  • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
  • G02F1/1333—Constructional arrangements; Manufacturing methods
  • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
  • G02F1/1336—Illuminating devices
  • G02F1/133602—Direct backlight
  • G02F1/133613—Direct backlight characterized by the sequence of light sources

Definitions

• the invention relates to an LED module and a method for producing an LED module.
• LED modules are used, for example, for backlighting LCDs. Many individual LEDs are arranged behind the display in one plane. One difficulty lies in this case is to arrive at a sufficiently homogeneous' backlighting. These homogeneity problems have two different causes: on the one hand, it would be difficult to build thin and homogeneous backlight units at the same time, if one had completely identical LEDs, since it already requires special efforts in the optical design to achieve this "intrinsic" homogeneity , on the other hand, the LEDs are not identical. One tries to obstruct possibly identical pre-sorted LEDs (so-called "binning").
• Another object of the invention is to provide a simple method of manufacturing an LED module with improved color homogeneity. This object is achieved by a method according to claim 11.
• An LED module comprises a carrier and a plurality of light sources each having one light emitting diode or a plurality of light emitting diodes, each light emitting diode having a color locus Fi and a brightness Hi and the light sources depending on the color loci Fi and / or the brightnesses Hi in a predetermined position on the support are arranged such that the LED module has a radiation homogeneity H BLU which is smaller than the statistical average H * one
• the LED module according to the invention is provided in particular for backlighting or illumination.
• the LED module can be used in a flat screen television for backlighting or as a radiation source for general lighting.
• the radiation homogeneity H BLU of the LED module is evaluated by a scalar quality function.
• the quality function is calculated as follows: take a number of test points on a radiation exit surface and determine the color location of each test point in the CIE u'v 1 space or CIE L * a * b * space. Then calculate the mean color location of the LED module and also calculate the distance from the mean color location for each test point.
• the quality function is preferably defined as twice the maximum resulting distance.
• the radiation exit surface is determined to be a surface located in a plane at a distance D from the support and extending over the entire extent of the LED module.
• the radiation homogeneity H BLU of the LED module is at most half as large as the statistical mean H * of the radiation homogeneity distribution.
• an advantageous simulation method is used to calculate the radiation homogeneity H BLU of the LED module.
• the brightness contribution of an LED is considered as a parameterized function of several variables.
• the variables are the location of the LED, the location of the considered point on the exit surface, and possibly other variables that cause variations in the LED emission characteristic (for example, the chip position tolerance).
• the brightness contribution of an LED is considered, for example, as an additive superposition of several two-dimensional Gaussian functions of different strength and width; Edge effects can be, for example, on the edge mirrored further, possibly elliptic Gaussian functions take into account.
• a continuous transfer function of the light from the single LED, which is located at a certain, but freely selectable location, to another, freely selectable location on the exit surface is thus determined by the parameters of the Gaussian functions used.
• the adaptation of these parameters can either be done by numerical optimization of the transmittance model to measurements or ray tracing simulations or "by hand".
• the quality function is then defined as the maximum resulting distance.
• the quality function of the radiation homogeneity H BLU can be determined from simulation results.
• the transfer function it is possible to determine the radiation homogeneity H BLU at an experimentally determined time of about 0.3 ⁇ s per function evaluation on a standard PC in about 3 seconds.
• the results are without any Statistical noise, but contain modeling errors, the size of which depends on the flexibility of the transfer function model used and the accuracy of the parameter adaptation.
• the speed advantage lies in putting all the optical behavior of a particular LED module design into the transfer function model one single time, and then using this model to calculate a variety of LED module configurations.
• each light source has a light-emitting diode or a plurality of light-emitting diodes.
• a light-emitting diode is preferably to be understood as meaning a radiation-emitting component having at least one semiconductor chip. However, it may also be meant a single radiation emitting semiconductor chip.
• the light-emitting diodes are mounted on a printed circuit board.
• each light source has at least two light-emitting diodes which emit radiation of different wavelengths.
• each light source can have at least one red, one green and one blue light-emitting diode.
• a plurality of RGGB clusters are used for the light sources, that is, clusters having one red, two green and one red include a blue LED.
• each light source may include at least one light emitting diode emitting white light.
• a method according to the invention for producing an LED module as described above has the following steps:
• FIG. 1 shows a schematic plan view of an LED module according to the invention
• FIG. 2 shows a histogram representing a frequency distribution W of the radiation homogeneity H BLU for a LED module with a random arrangement of the light sources
• Figure 3 is a schematic representation of a light source arrangement in a conventional and in an LED module according to the invention.
• the LED module 10 shown in FIG. 1 has 1152 LEDs 2.
• the LEDs 2 result in 48 light sources 1 each having 24 LEDs 2 in juxtaposed RGGB clusters 3.
• the light sources 1 are arranged on a carrier (not shown) in the manner of a matrix having twelve rows and four columns.
• the 48 light sources 1 of the same design can basically be installed in any order. At 48 light sources
• the light sources 1 are then arranged on the carrier such that the radiation homogeneity H BLU of the LED module 10 is smaller than the statistical average H *.
• the color locus Fi and the brightness Hi of the LEDs 2 are first determined. For reasons of production control, the color location Fi and the brightness Hi of the individual LEDs 2 of each ready-equipped light source 1 are measured again anyway, although the LEDs 2 are typically already grouped prior to assembly according to color locus F ⁇ and brightness Hi. The measurement for the purpose of determining the radiation homogeneity distribution therefore does not provide any.
• each individual light source 1 is marked, such as with a bar code label, so that each light source 1 is identifiable.
• the so-called “final clearance w " measurement data of the individual light sources 1 can be stored, for example, together with the bar code of each light source 2 in the PCB assembler in a database. While the light sources 1 are packaged together in kits for each LED module 10 and transported for final assembly, the optimization calculation can take place advantageously offline, which will be described in more detail below. Their result can be transmitted to the final assembly electronically.
• the worker scans the bar code (he has to do anyway, because of the traceability) and then gets the space provided for the light source 1 on a screen.
• the space can also be displayed by marking the corresponding location on the carrier with an automatically controlled lamp.
• the final assembly can also be carried out automatically, for example by means of a robot. In both cases (manual assembly or automated assembly), the sum of the travel paths is not increased by the optimization method.
• the information available at the light source level is used for the simulation of the
• Radiation homogeneity distribution used. One can try with the available information, by numerical optimization, a best possible arrangement of the light sources 1 to so that the finished LED module has an optimized radiation homogeneity H BLU .
• the already existing information about the color locus Fi and the brightness Hi of LEDs used and translated into an easily automatable and almost no additional effort implementable manufacturing instructions Not only bad LED modules are avoided, but the radiation homogeneity H is systematically and considerably improved for practically all LED modules.
• FIG. 2 shows the result of a calculation according to the invention. On the abscissa is the
• Radiation homogeneity H in JNDs (Just Noticeable Differences).
• the ordinate indicates the frequency W of the radiation homogeneity H for a given number of random arrangements, in this case for 2000 random arrangements, in the respective interval.
• the histogram distribution in this case has a statistical mean H * of around 4 JNDs and a total width of around 3 JNDs.
• the best value of the 2000 random arrays is around 2.5 JNDs.
• the bar at 1.5 JNDs shows the value of the optimum arrangement determined by the optimization procedure from a total of about 2,000 tested assemblies. It is not a contradiction that the found optimum lies far outside the histogram distribution. This only shows that the actual distribution is significantly wider than you can see with only 2000 random experiments.
• red, green and blue LEDs are pre-sorted in bins for brightness and color location and mounted "bin-pure" on printed circuit boards, with a light source 1 of 24 LEDs will be produced.
• the light sources 1 are mounted on the carrier in a random arrangement.
• the method can be easily transferred to other evaluation functions that also evaluate the gradients in addition to the color locus and / or the brightness.

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• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Nonlinear Science (AREA)
• Optics & Photonics (AREA)
• Chemical & Material Sciences (AREA)
• Mathematical Physics (AREA)
• General Engineering & Computer Science (AREA)
• Crystallography & Structural Chemistry (AREA)
• Microelectronics & Electronic Packaging (AREA)
• General Physics & Mathematics (AREA)
• Led Device Packages (AREA)
• Planar Illumination Modules (AREA)
• Non-Portable Lighting Devices Or Systems Thereof (AREA)

Applications Claiming Priority (2)

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• 2008
  • 2008-03-05 US US12/529,802 patent/US8360601B2/en active Active
  • 2008-03-05 JP JP2009553002A patent/JP2010521066A/ja active Pending
  • 2008-03-05 CN CN2008800076728A patent/CN101627332B/zh active Active
  • 2008-03-05 WO PCT/DE2008/000394 patent/WO2008110142A1/de not_active Ceased
  • 2008-03-05 DE DE112008001265T patent/DE112008001265A5/de not_active Withdrawn
  • 2008-03-05 EP EP08715543A patent/EP2057503A1/de not_active Withdrawn
  • 2008-03-05 KR KR1020097020899A patent/KR20090125267A/ko not_active Ceased
  • 2008-03-07 TW TW097108047A patent/TWI402963B/zh active

Non-Patent Citations (1)

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