EP1920286A2

EP1920286A2 - Light emitting module especially for use in an optical projection apparatus, and optical projection apparatus

Info

Publication number: EP1920286A2
Application number: EP06791329A
Authority: EP
Inventors: Stefan GRÖTSCH; Sergey Kudaev; Bryce Anton Moffat; Peter Schreiber
Original assignee: Osram Opto Semiconductors GmbH
Current assignee: Ams Osram International GmbH
Priority date: 2005-08-31
Filing date: 2006-08-31
Publication date: 2008-05-14
Also published as: JP5661241B2; CN101365976A; CN101365976B; JP2009506559A; US7976205B2; TWI341142B; KR20080054389A; DE102005054955A1; TW200715904A; WO2007025525A3; US20090129079A1; WO2007025525A2

Abstract

Disclosed is a light emitting module (20) comprising at least two light sources (1) which are applied to a common support (7). At least one of the light sources (1) encompasses at least two light emitting diode chips (2). An optical member (3) of an optical element (5) is mounted downstream from each light source (1) of the module. Said optical members (3) are suitable for guiding electromagnetic radiation to a light discharging area (4) of the optical element (5). Also disclosed is an optical projection apparatus comprising such a light emitting module.

Description

description

Light-emitting module, in particular for use in a projection optical device and optical projection device

A light-emitting module is specified. The light-emitting module is particularly suitable for use in a projection optical device. In addition, an optical projection apparatus is specified with such a light-emitting module.

Document EP 100 30 62 A1 describes an optical projection apparatus.

An object to be solved is to specify a particularly compact light-emitting module. Another object to be solved is to provide a light-emitting module which has an increased mechanical stability. Furthermore, it is an object to provide a particularly compact optical projection apparatus.

In accordance with at least one embodiment of the light-emitting module, the light-emitting module has at least two light sources. The light sources are applied to a common carrier.

The carrier is, for example, a circuit board. The carrier then has printed conductors and contact points, by means of which the light sources of the module are electrically contacted. Further, the carrier is preferably suitable to dissipate heat generated during operation of the light sources. The carrier preferably has a good thermal conductivity for this purpose. For example, it is the carrier around a printed circuit board (PCB) or more preferably around a metal core board containing a metal such as copper or aluminum.

In accordance with at least one embodiment of the light-emitting module, one of the light sources comprises at least two light-emitting diode chips. That is to say that at least this light source contains as light-generating elements two or more than two light-emitting diode chips which, upon contacting the light source, can jointly produce electromagnetic radiation, preferably simultaneously. It is also possible for the light-emitting diode chips of the light source to be able to be contacted separately from one another. The light-emitting diode chips of the light source are arranged, for example, to form a square or rectangular array of N × M light-emitting diode chips. For example, a light source may have 2 × 3 light-emitting diode chips. The light-emitting diode chips are arranged in two rows of 3 light-emitting diode chips each. Further light sources of the light-emitting module may comprise individual light-emitting diode chips or likewise a plurality of light-emitting diode chips.

In accordance with at least one embodiment of the light-emitting module, each light source of the module is followed by an optical body of an optical element. In this case, "subordinate" means that the optical body follows the light source in a main emission direction of the light source The optical body is arranged relative to the light source in such a way that a large part of the electromagnetic radiation generated by the light source during operation enters the optical body and passes through the optical body Optic body of this can be optically influenced. Preferably, each light source is uniquely associated with an optical body of the optical element. That is, the optical element has a plurality of optical bodies. The number of optical bodies corresponds to the number of light sources. Each light source is associated with a separate optical body of the optical element. This also means that at least in that light source which comprises at least two light-emitting diode chips, this plurality of light-emitting diode chips is arranged downstream of a common optical body.

In accordance with at least one embodiment of the light-emitting module, the optical bodies are suitable for guiding electromagnetic radiation generated during operation of the light sources to a light exit surface of the optical element. That is, the optical bodies are arranged such that they guide electromagnetic radiation generated by the light sources of the module during operation from the light sources to a light exit surface of the optical element. The light exit surface of the optical element can be contained in a separate from the Optikkδrpern component of the optical element. For this purpose, the light exit surface of the optical element may be formed for example by the surface of a cover plate of the optical element. But it is also possible that the light exit surface of the optical element is formed by the light exit surfaces of the optical body and is composed for example of these.

The light exit surface of an optic body is that surface through which a large part of the electromagnetic radiation coupled into the optic body leaves it again. Electromagnetic radiation, which the light exit surface of the optical body in the direction of the Radiating out optics body, can no longer be optically influenced by the optical body.

If the optic body is formed by a hollow body, I can also act at the light exit surface to a virtual or imaginary surface. As soon as electromagnetic radiation has penetrated this surface in the direction away from the optical body, the radiation can no longer be visually influenced by the optical body. For example, the imaginary surface is limited by the upper edge of the optical body remote from the light source.

The light exit surface of the optical element and / or the light exit surfaces of the optical body are preferably suitable for optically influencing the electromagnetic radiation passing through them. These surfaces can then serve for beam shaping of the electromagnetic radiation passing through the optical element. Furthermore, it is possible for the light exit surfaces of the optical element and / or the optic bodies to be suitable for reducing the probability of total reflection upon the exit of radiation from the optical element. The light exit surfaces then serve to increase the beam power of the light-emitting module. Furthermore, the component of the optical element which comprises the radiation exit surface can also represent mechanical protection, for example of the light sources, from contact or soiling.

In accordance with at least one embodiment of the light-emitting module, the light-emitting module has at least two light sources which are applied to a common carrier. At least one of the light sources comprises in this case, two light-emitting diode chips, wherein each light source is arranged downstream of an optical body of an optical element, and the optical body are adapted to guide electromagnetic radiation to a light exit surface of the optical element.

In accordance with at least one embodiment of the light-emitting module, at least one of the optical bodies of the optical element comprises a non-imaging optical concentrator. Preferably, all optical bodies of the optical element are formed by non-imaging optical concentrators. Preferably, the optical concentrator tapers towards the light source, to which it is arranged downstream. In other words, its cross-sectional area increases as the distance to the light source increases. The optical body may consist of a concentrator or in addition to the concentrator other components - for example, a cover - include.

The optical body can be formed at least in places in the manner of one of the following basic optical elements: Compound Parabolic Concentrator (CPC), Compound Elliptic Concentrator (CEC), Compound Hyperbolic Concentrator (CHC). The side surfaces of the optical body are then formed at least in places in the manner of one of these optical basic elements.

Furthermore, it is possible that the optical body is shaped at least in places in the manner of a truncated cone or a truncated pyramid, which tapers towards the light source. The optical body may be formed in all these embodiments as a solid body. In this case, a guidance of electromagnetic radiation in the optical body takes place at least partially by means of total reflection at its side surfaces. In addition, the surface of the solid body may be coated at least in places with a reflective material.

Furthermore, it is possible that the optic body is designed as a hollow body whose inner surfaces are designed to be reflective. For example, the inner surfaces of the optical body are then coated with a reflective metal. If the optical body is formed by a hollow body, then the light exit surface is that imaginary, flat surface which covers the opening of the optical body facing away from the light source. That is, this surface connects the side surfaces of the optical body at its light exit opening.

According to at least one embodiment of the light-emitting module, the optical body comprises a non-imaging optical concentrator, which is designed as a truncated pyramid. That is, the optical body has, for example, a rectangular light entrance surface and a rectangular light exit surface which are interconnected by the side surfaces of the optical body.

The truncated pyramid can be symmetrical. That is, it is symmetrical with respect to a central axis which passes through the geometric center of the light entrance surface and is perpendicular to the light entrance surface. This central axis then passes through the geometric center the light exit surface. Furthermore, it is possible for the optical body to be formed by an asymmetrical truncated pyramid, in which the center axis does not coincide with the center axis through the geometric center of the light entry surface through the geometric center of the light exit surface.

The specified light-emitting module makes use, inter alia, of the finding that by using a plurality of optical concentrators as optical bodies, which are respectively arranged downstream of groups of light-emitting diode chips and the same optical effect can be achieved by a common light-emitting surface of the optical element, as if all light-emitting diodes of Module would be a single, common optical concentrator downstream. In contrast to such a single optical concentrator, the light-emitting module described here is distinguished by a length of the optical element which is reduced by up to about 50 percent. That is, because of the use of multiple optical concentrators, the concentrators can be made shorter. Such an optical element therefore enables a particularly compact light-emitting module. Furthermore, the reduced length of the optical element results in increased mechanical stability of the light-emitting module.

In accordance with at least one embodiment of the light-emitting module, the optical body is formed by a solid body. This proves to be particularly advantageous, for example, when the optic body is designed as a truncated pyramid. The optical body formed as a solid body preferably contains a transparent material with a refractive index greater than 1.4. Reflections on the side surfaces of the Optikkδrpers done then preferably by total reflection. The optical body may be formed, for example, of a transparent plastic or glass. If the optic body consists of a transparent plastic, then it is preferably injection-molded or injection-molded. The optic body then preferably contains or consists of at least one of the following materials: PMMA, PMMI, PC, COC (for example, Zeonex or Topas), silicone.

The light exit surface of the optical body is preferably formed integrally with the optical body when formed as a solid optical body. It can be designed as smooth or as a surface with a curvature.

In accordance with at least one embodiment of the light-emitting module, the optical element is formed in one piece. That is, the optical elements of the optical element, and optionally other components of the optical element are integrally connected to each other. For this purpose, the optical element is produced for example by means of an injection molding or transfer molding process. The width of the web caused by the manufacturing process between the individual optical bodies of the optical element is preferably chosen to be as small as possible. This ensures that the optical properties of the optical element are influenced as little as possible by the web. The integrally formed optical element is characterized by its compactness by a particularly simple handling during assembly of the optical element on the support of the light-emitting module.

In accordance with at least one embodiment of the light-emitting module, the optical element of the module is multi-piece educated. That is, components of the optical element are made separately from each other. These components can also be injection-molded or injection-molded, for example. Preferably, the optical body of the optical element are made separately from each other. The optical bodies can have light exit surfaces, which form the light exit surface of the optical element in the assembled optical element. Furthermore, it is possible that the component which contains the light exit surface of the optical element is manufactured separately from the optical elements or both the optical elements are manufactured separately from one another as well as the component which comprises the light exit surface of the optical element. In separately formed optical bodies can advantageously account for a web between the optical bodies.

According to at least one embodiment of the light-emitting module, the light exit surface of the optical element is formed by a convex surface which extends over the light exit surfaces of the optical body. The light exit surface of the optical element can be curved, for example, over the optic body of the optical element. In other words, the light exit surface then spans the optic bodies in the sense of a dome. The light exit surface in this embodiment may be part of a separate component of the optical element, which is manufactured separately from the optical bodies - for example, a curved cover plate of the optical element.

But it is also possible that the light exit surface of the optical element is formed in places by light exit surfaces of the optical body. In this case, the Light exit surface of the optical element of light exit surfaces of the optical body together. For example, each of the optical bodies can have a light exit surface, which forms part of the light exit surface of the optical element. The composite optical element then has a light exit surface which extends over the light exit surfaces of the optical body and consists of these.

In accordance with at least one embodiment of the light-emitting module, the optical element of the module has a light exit surface with convex subregions which are interconnected by concave subregions. The convex portions may extend over the light exit surfaces of several optical bodies. But it is also possible that convex portions are associated with the optical bodies one-to-one. In this case, for example, a curvature of the light exit surface of the optical element can be arranged downstream of each optical body, which then mainly optically influences the electromagnetic radiation passing through this optical body. Concave subregions which connect the convex subareas to one another comprise both concavely curved subareas of the light exit surface of the optical element and also peaks, notches and other indentations of the light exit surface. Furthermore, it is possible that the convex partial regions are connected to one another by flat surface sections of the light exit surface of the optical element.

In addition to its optical properties, a curved light exit surface also proves in the manufacture of the Optic body as advantageous. If the optical body is a solid body, uncontrollable production fluctuations during curing of the optical body can occur during the production of an optical body with a planar light exit surface. That is, the light exit surface then has convexly and concavely curved partial areas in a non-predeterminable manner. By contrast, a curved light exit surface with a predetermined radius of curvature allows the light exit surface itself to stabilize. Curved portions of the light exit surface preferably have a radius of curvature of at least 100 mm, preferably at least 50 mm.

In accordance with at least one embodiment of the light-emitting module, the light exit surface of the optical element is composed of the light exit surfaces of the optical body. That is, the light exit surface of the optical element is not a separate component of the optical element, but it is composed of several parts, each of which forms light exit surfaces of an optical body. This is preferably the case when the optical element is formed in several pieces, and the optical body are made separately from each other. The optic bodies can then each have, for example, convexly curved light exit surfaces. The optic bodies are designed in such a way that the

Light exit surfaces of the optical body in the composite optical element form-fitting complement to a light exit surface of the optical element.

In this case, for example, a light exit surface of the optical element, which extends as a curved surface over all the optical body, through the light exit surfaces the optic body be formed. Light that passes through the light entry surface into an optical body can then emerge with a certain probability through the radiation exit surface of another optical body, which is arranged for example adjacent.

Overall, the composite light exit surface of the optical element thus forms an optical base element - for example, a concentrator lens - for the entire optical element. That is, a common

Concentrator lens for the light of all light sources of the module is formed only by the assembly of the individual optical body. In other words, the optical properties of the light exit surface of the optical element are not given by a simple addition of the optical properties of the light exit surfaces of separate optical body.

In accordance with at least one embodiment of the light-emitting module, the light-emitting module has at least one optical body whose light-entry surface has an antireflection coating comprising a dielectric material. This coating is used for anti-reflection of the light entry surface of the Optikkδrpers and thus increases the probability of the light entering the optic body. Preferably, light entry surfaces of all optical bodies of the optical element are coated in this way. Furthermore, it is possible that the light exit surface of the optical body and / or the light exit surface of the optical element also has such a coating. For example, the coating of the light transmission surfaces of the optical element can be effected by means of a dip coating method. In particular, porous sol-gel Layers that allow a particularly cost-effective coating of the plastic or glass from which the components of the optical element are made.

In accordance with at least one embodiment of the light-emitting module, the light entry surface of at least one optical body has a periodic microstructure which is suitable for reducing the reflection of electromagnetic radiation. Such periodic microstructuring can be done, for example, alternatively or in addition to an antireflection coating. By adapting the period and depth of the periodic microstructure, the antireflection coating can be optimized to the desired wavelength range. If the periodic microstructuring, for example, wave-shaped with a period between three and seven microns and a depth between six and nine microns executed, the structuring is particularly well suited for an anti-reflection in the wavelength range of ten to twenty microns. With a correspondingly selected period of microstructuring, antireflection in the visible range is also possible. The period length of the structuring is preferably smaller than the wavelengths to be soiled.

For example, the structuring can take place by the impression of holographically produced stamps in the material of the optic body, which in this case is preferably formed as a solid body. In addition to the light entry surfaces of the optic bodies, further light transmission surfaces of the optical element, such as the light exit surface of the optic body and / or of the optical element, can also have such periodic microstructuring for antireflection coating. In accordance with at least one embodiment of the light-emitting module, at least one of the light-emitting diode chips of the module is free of a potting compound. That is, this LED chip is not subordinate example, epoxy resin or silicone-containing encapsulation. The LED chip is therefore not embedded in a potting compound. The light output surface of the LED chip is freely accessible. This LED chip is the

Subordinate light input surface of an optical body, so that light of the LED chip radiates into the optical body, without having previously irradiated a potting compound. This allows the irradiation of electromagnetic radiation in the optical body without a partial absorption of the electromagnetic radiation takes place in a potting compound. Furthermore, it can not lead to aging or peeling of the potting compound.

In accordance with at least one embodiment of the light-emitting module, an air gap is arranged between the light output surface of a light-emitting diode chip of the module and the radiation entrance surface of the optical body associated with the light-emitting diode chip. That is, the light entrance surface of the optical body and the light outcoupling surface of the LED chip are not connected to each other by a potting compound or refractive index-matching material, for example, an index matching gel, but there is a gap between these surfaces, which is preferably filled with air , It is possible that the light-emitting diode chip has a thin encapsulation, which does not extend to the light entry surface of the optical body or that the LED chip is shedding-free. In accordance with at least one embodiment of the light-emitting module, the distance between the light entry surface of an optical body of the optical element and the light exit surface of at least one light-emitting diode chip is not more than 250 μm, preferably not more than 200 μm, particularly preferably not more than 100 μm. In the case of a potting chip without potting, the spacing is limited only by a possible contacting wire via which the light-emitting diode chip is electrically contacted on the n-side, for example. Such a small distance between the light entry surface of the optical body and the light output surface of the LED chip allows the coupling of the largest possible portion of the light emitted by the LED chip in the optical body.

In accordance with at least one embodiment of the light-emitting module, the optical element has a holder to which the optical bodies are attached. The holder may be a separate component of the optical element or the holder is formed integrally with the optical element. The optic bodies are preferably fastened to this holder on their sides facing away from the light entry surfaces. The optical body can be glued, snapped or inserted, for example, on the holder. Further, it is possible that the optical bodies are integrally connected to the holder. In this case, the optical body can be manufactured together with the holder in an injection molding or transfer molding process. Furthermore, it is possible for a component of the optical element-for example a cover plate, which includes the light exit surface of the optical element-to be fastened to the holder or to be formed integrally therewith. The holder is preferably frame-like, box-like or designed in the manner of a hollow cylinder with a round or oval base. The components of the optical element, such as the optical body, are then preferably attached to the side facing away from the carrier of the module of the holder thereto.

Among other things, the frame-shaped holder makes use of the knowledge that thermal stresses of the optical element are compensated particularly well by such a holder. For example, when the optical element heats up during operation of the light sources, the holder mounted on the carrier expands away from the carrier. The optic bodies, which are preferably fastened to the side of the holder facing away from the carrier, extend from the side of the holder facing away from the carrier to the carrier. In this way, the thermal expansions of the holder away from the carrier and the optical body to compensate for the carrier out. The distance of the light outcoupling surfaces of the LED chips from the light entry surfaces of the optical body remains in this way at least approximately constant. Preferably, holders and optics body thereby

I matched to each other thermal expansion coefficients and are formed, for example, from the same material.

In accordance with at least one embodiment of the light-emitting module, the holder encloses the optical bodies of the optical element from at least four sides. In this case, side surfaces of the holder extend along the optical body. The holder can be designed for this purpose, for example, in the manner of a box or a hollow cylinder. In accordance with at least one embodiment of the light-emitting module, the holder encloses the light sources of at least four sides. For this purpose, the holder may be formed, for example, box-like. The side surfaces of the holder are at least in places in contact with the support of the module - for example, they rest on the support. In this way, the holder provides mechanical protection of the light sources, which include, for example, non-cast LED chips.

Furthermore, an optical projection device is specified. The optical projection device preferably has at least one light-emitting module according to at least one of the embodiments described above. The optical projection apparatus preferably has a plurality of such light-emitting modules which, for example, could be suitable for producing light of different colors. Thus, one of the modules may be suitable for emitting light in the green spectral range. Another module may be suitable for emitting light in the red spectral range. A third module may be suitable for generating light in the blue spectral range.

In accordance with at least one embodiment of the optical projection apparatus, the light-emitting modules are arranged on the side surfaces of a dichroic beam distributor (X-cube). If red, blue and green light are emitted at the same time and with suitable intensities in three different side surfaces in this X-Cube, white mixed light leaves the X-Cube through another side surface.

In accordance with at least one embodiment of the optical projection apparatus, the optical projection apparatus can continue an imaging unit such as an array of separately controllable micromirrors (DMD) or an LCD panel.

In accordance with at least one embodiment of the optical projection apparatus, the optical projection apparatus may include a projection lens which is suitable for projecting the light originating from at least one of the light-emitting modules onto a projection surface.

Further advantages, preferred embodiments and further developments of the light-emitting module and of the optical projection apparatus are evident from the exemplary embodiments explained below in conjunction with the figures:

Show it:

FIG. 1 shows a schematic perspective sketch of a first exemplary embodiment of the light-emitting module described here,

FIG. 2A shows a schematic perspective sketch of a second exemplary embodiment of the light-emitting module described here,

FIG. 2B shows a schematic perspective sketch of the optical element for the second exemplary embodiment of the light-emitting module,

FIG. 2C shows a schematic sectional view of the optical element, as shown in FIG. 2A, seen from a first direction, FIG. 2D shows a schematic sectional illustration of the optical element, as shown in FIG. 2A, seen from a second direction,

FIG. 3 shows a schematic perspective sketch of a third exemplary embodiment of the light-emitting module described here,

4A shows a schematic perspective sketch of a fourth exemplary embodiment of the light-emitting module described here, FIG.

FIGS. 4B and 4C are schematic perspective sketches of optical bodies of the optical element of the fourth embodiment;

FIG. 4D shows a schematic sectional view of an optic body as used in the fourth exemplary embodiment of the module,

FIG. 5 the course of an optimized light exit surface for an exemplary embodiment of the optical element,

FIGS. 6A and 6B are schematic sectional views of optic bodies for embodiments of the optical element;

Figures 7A, 7B and 7C are schematic sectional views of embodiments of the optical element, and

Figure 8 is a schematic sectional view of an embodiment of the optical Proj ektionsgerätes described here. In the exemplary embodiments and figures, identical or identically acting components are each provided with the same reference numerals. The components shown and the size ratios of the components with each other are not to be considered as true to scale. Rather, some details of the figures are exaggerated for clarity.

FIG. 1 shows a schematic perspective sketch of a first exemplary embodiment of a light-emitting module described here.

The light-emitting module 20 of the first embodiment has two light sources 1. The light sources 1 each comprise two times three light-emitting diode chips 2. Each light source 1 is arranged downstream of the optical body 3 of an optical element 5.

The optical bodies 3 of the embodiment of FIG. 1 are non-imaging concentrators which are designed in the manner of a CPC optic described above. Preferably, these concentrators are designed as solid bodies, so that the side walls guide the light from the radiation entrance surface to the radiation exit surface 4 by total internal reflection.

The optical bodies 3 guide the light of the light sources 1 to a cover plate of the optical element 5, which comprises the radiation exit surface 4 of the optical element 5. The radiation exit surface 4 of the optical element 5 is arranged downstream of the radiation exit surfaces 40 of the optical body 3. The optical body 3 and the radiation exit surface 4 are fastened to a holder 13, which comprises dowel pins 8. The dowel pins 8 engage in corresponding recesses 6 of the carrier 7 of the light-emitting module 20. The dowel pins 8 contribute to the mechanical fastening and / or to the adjustment of the optical element 5 on the carrier 7.

The carrier 7 is formed for example by a metal core board, which may have holes 12, via which the carrier 7 on a module carrier (not shown) attached, for example, can be screwed. The metal core board preferably contains good heat-conducting metals such as aluminum or copper.

The carrier 7 has' printed conductors 9, which connect a plug connection 10, by means of which the module can be electrically contacted from the outside, with the light sources 1.

The light-emitting diode chips 2 of the light sources 1 are applied, for example, to a ceramic carrier 11, which has plated-through holes (vias) in order to contact the light-emitting diode chips 2 with the conductor tracks 9 of the carrier 7. The radiation decoupling surface of a light-emitting diode chip 2 of a light source 1 has, for example, an area of approximately one mm ² . The spacing of the light-emitting diode chips 2 of a light source 1 with one another is preferably less than 100 μm.

The light-emitting diode chips 2 are particularly preferably so-called thin-film light-emitting diode chips. That is to say, at least one light-emitting diode chip 2 has a light output surface through which a large part of the electromagnetic radiation emitted by the light-emitting diode chip 2 is coupled out. Particularly preferably, the entire radiation emitted by the light-emitting diode chip 2 emerges through the light output surface. The light output surface is given for example by a part of the surface of the LED chip 2. Preferably, the radiation coupling-out surface is provided by a main surface of the light-emitting diode chip 2, which is arranged, for example, parallel to an epitaxial layer sequence of the light-emitting diode chip 2, which is suitable for generating electromagnetic radiation.

For this purpose, the epitaxial layer sequence can have, for example, a pn junction, a double heterostructure, a single quantum well or a multiple quantum well structure (MQW). The term quantum well structure may include any structure in which carriers undergo quantization of their energy states by confinement. In particular, the term quantum well structure does not include information about the directionality of the quantization. It thus includes quantum wells, quantum wires and quantum dots and any combination of these structures.

Preferably, the light-emitting diode chip 2 is a light-emitting diode chip in which the growth substrate is at least partially removed and on the surface facing away from the original growth substrate, a carrier element is applied. The carrier element can, compared with a

Growth substrate, are chosen relatively freely. Preferably, a carrier element is selected which is particularly well adapted to the radiation-generating epitaxial layer sequence with regard to its temperature expansion coefficient. Further, the carrier element may contain a material which is particularly good heat-conducting. In this way, the heat generated by the LED chip 2 during operation is dissipated to the carrier 7 in a particularly efficient manner.

Such light-emitting diode chips 2 produced by removing the growth substrate are often referred to as thin-film light-emitting diode chips and are preferably distinguished by at least one of the following features:

At a first major surface of the radiation-generating epitaxial layer sequence facing the carrier element, a reflective layer or layer sequence is applied or formed which reflects back at least part of the electromagnetic radiation generated in the epitaxial layer sequence.

The epitaxial layer sequence preferably has a thickness of not more than 20 μm, particularly preferably not more than 10 μm.

Furthermore, the epitaxial layer sequence preferably contains at least one semiconductor layer with at least one surface which has a mixing structure. Ideally, this intermixing structure leads to an approximately ergodic distribution of the light in the epitaxial layer sequence, ie it has the most ergodic, stochastic scattering behavior possible. A basic principle of a thin-film LED chip is described, for example, in the publication I. Schnitzer et al. , Appl. Phys. Lett. 63 (16), 18 October 1993, pages 2174 to 2176, the disclosure of which is hereby incorporated by reference, the basic principle of a thin film light-emitting diode chip.

The distance between the centers of the two light sources 1 of the light-emitting module 20 is in the embodiment of Figure 1 between five and six mm.

FIG. 2A shows a schematic perspective illustration of a second exemplary embodiment of the light-emitting module 20 described here.

In contrast to the exemplary embodiment described in conjunction with FIG. 1, the light-emitting module 20 of FIG. 2A has a box-like holder 13 of the optical element 5. That is, the optical element 5 has a holder 13 (see also the sectional view along the lines AA 'of Figure 2B and the sectional view along the lines BB' of Figure 2C), which encloses the light sources 1 and the optical body 3 from four sides , Here are side surfaces of the holder 13 in places on the carrier 7. Thus, the optical element 5 of FIG. 2A represents a mechanical protection of the light-emitting diode chips 2 and the optical body 3. The light-emitting diode chips 2 can therefore be cast-free, for example. The light entry surfaces 14 of the optical body 3 are preferably arranged at a distance of between 100 and 250 μm from the radiation decoupling surface of the light-emitting diode chips 2. The gap between LED chips 2 and light entry surface 14 is preferably filled with air. The optical body 3 of the optical element 5 are in the embodiment of Figure 2A preferably separately manufactured solid body, which are attached to the holder 13. They each have a radiation exit surface 40. The radiation exit surfaces 40 of the optical body 3 complement each other to the radiation exit surface 4 of the optical element 5 (see also the schematic sectional views of Figures 2C and 2D). In this case, it is possible for light entering through the radiation entrance surface 14 of an optical body 3 to emerge from the optical element 5 through the radiation exit surface of another optical body. For example, the optic bodies 3 are truncated pyramidal optics. The light of the array of light-emitting diode chips 1 divided into two light sources 1 is then collected by the optical bodies 3 and redistributed onto a rectangular light-emitting surface 4 of the optical element 3.

The optical element 5 is preferably fastened and / or adjusted on the carrier 7 by means of dowel pins 8, which have a star-shaped cross section. The length of the carrier 7 in the embodiment of the light-emitting module 20 shown in connection with FIG. 2A is approximately 4.0 cm. The width is about 2.5 centimeters. The height of the optical element 5 is approximately 2.5 cm from the carrier to the vertex of the radiation exit surface 4. Each optical body 3 is arranged downstream of an array of 2 x 3 LED chips 2. In comparison, a single optical body arranged after twelve light-emitting diode chips would have to be approximately twice the length in order to achieve the same optical effect as the optical element 5 as described in connection with FIG. 2B. FIG. 3 shows a schematic perspective sketch of a third exemplary embodiment of the light-emitting module described here. In this embodiment, the optical element 5 is integrally formed. Between the optic bodies 3, which are formed as a truncated pyramid, is due to the manufacturing process, a web 17. The web 17 is preferably selected to be particularly thin, as little as possible to influence the optical properties of the optical element 5. Preferably, the width of the web 17 is at most 0.25 mm.

FIG. 4 a shows a schematic perspective sketch of a fourth exemplary embodiment of the light-emitting module described here. Figures 4B and 4C show schematic perspective views of the optical body 3 of this module. The optical body 3 are attached to a holder 13. Their light exit surfaces 40 complement each other to the light exit surface 4 of the optical element 3. It is possible that radiation which is coupled to the light entrance surface 14 of the one optic body 3 exiting through the radiation exit surface 40 of the other optical body from the module. The composite light exit surface 4 therefore represents a light exit surface for the entire module 20.

The optical body 3 of the optical element 5 have in this embodiment asymmetric truncated pyramids 3a as optical concentrators. That is, a central axis that is perpendicular to the radiation entrance surface 14 through its geometric center does not coincide with a central axis that passes through the geometric center of the light exit surface 40. The light exit surface 4 of the optical element preferably serves as Concentrator lens. Its decentralized arrangement relative to the radiation entrance surface 14 of the optical body 3 contributes to the compensation of the asymmetry of the truncated pyramid 3a, which forms the optical body 3 at. FIG. 4D shows, in a schematic sectional illustration of the optical element 3, using example beams, how a decentralized lens-shaped light exit surface 40 can compensate the asymmetry of the asymmetrical truncated pyramid 3a.

FIG. 5 shows an optimized course of the

Radiation exit surface 40 for an optical body as it is shown for example in conjunction with Figures 6A and 6B. FIG. 5 shows the course of the radiation exit surface 40 from the middle to the edge. FIG. 5 indicates the arrow height (Sag) in millimeters depending on the radius. The light exit surface 40 of the optic body 3 is optimized, for example, by means of a raytracing method. Table 1 indicates the coordinates of selected points on the radiation exit surface 40 to an optical body 3.

FIG. 6A shows a schematic sectional view of an optical body 3 with a radiation exit surface 40. The length of the truncated pyramid 3a is, for example, approximately 18 mm. The thickness of the cover plate 3b, which follows the truncated pyramid 3a and is preferably integrally formed therewith, is approximately 2.5 mm. The length of the optical body 3 from the radiation entrance surface 14 to the vertex of the radiation exit surface 40 is approximately 22 mm. The radiation exit surface 40 of the optic body 3, as shown in FIG. 6A, has a convex curvature 15. FIG. 6B shows a schematic sectional representation of optic bodies 3, which are connected to one another at their radiation exit surfaces 40. The radiation exit surfaces 40 of the optical body 3 are complementary to

Radiation exit surface 4 of an optical element 5. The radiation exit surface 4 of the optical element has convexly curved partial regions 15 and concavely curved partial regions 16.

Figures 7A, 7B and IC show schematic sectional views of optical elements 5 which are each "two light sources 1 arranged downstream.

The optical body 3 of Figure 7A each have planar light exit surfaces 40, which together form a flat light exit surface 4 of an optical element 5.

FIG. 7B shows two optical bodies 3 which each have a curved light exit surface 40. The light exit surfaces 40 of the optical body 3 are complementary to a light exit surface 4 of the optical element 5, which is curved over both Optikkδrper 3 and extends like a dome over the optical body 3.

FIG. 7C shows two optical bodies 3 in which the light exit surfaces 40 are each arched in the manner of a lens. The light exit surface 4 of the optical element 5 composed of the light exit surfaces 40 of the optical body 3 has convex partial regions 15 and a concave partial region 16 which connects the convex partial regions 15 to one another. The concave portion 16 is at the point where the Optikkδrper 3 touch, given by a tapered trench, located in the Radiation exit surface 4 of the optical element 3 extends.

The optical elements 5 of FIGS. 7A to 7B are preferably designed in two parts and are assembled at the radiation entrance surfaces 40 of the optical body 3. The optical body 3 can be glued together and / or they are held together by a holder 13.

The radiation entrance surfaces 14 and the radiation exit surfaces 40 of the optic bodies 3 may additionally have coatings (not shown) or periodic microstructures ("moth eye structures") which are suitable for antireflecting these light transmission surfaces

Light entrance surface 14 of the optical body 3 is due to the proximity to the heat-generating in operation light sources to ensure a particularly high heat and heat exchange resistance.

Figure 8 shows a schematic sectional view of an embodiment of the optical projection device described here. The optical projection device has three light-emitting modules 20, as described for example in the preceding embodiments. For example, one of the modules 20a is capable of producing red light. Another module 20b may be capable of producing blue light. The third module 20c may be adapted to produce green light. The modules 20a to 20c are arranged on the side surfaces of an X-Cube 30 into which they can radiate their light. Depending on which of the modules light up at the same time, radiation 34 leaves the X-Cube 30. The radiation 34 strikes an array of separately controllable micromirrors 31, which serves as an imaging element. Alternatively, LCD flashes may be disposed between the modules 20a-20c and the X-cube as imaging elements. Part of the radiation 35 reflected by the micromirrors passes through a projection lens 32 and is projected from there onto a projection screen.

This patent application claims the priority of German patent applications 102005041319.6 and 102005054955.1-51, the disclosure of which is hereby incorporated by reference.

The invention is not limited by the description with reference to the embodiments. Rather, the invention encompasses any novel feature as well as any combination of features, including in particular any combination of features in the claims, even if this feature or combination of features is not explicitly stated in the patent claims or embodiments.

Claims

claims

A light emitting module (20) having at least two light sources (1) mounted on a common carrier (7), wherein

At least one of the light sources (1) comprises at least two light-emitting diode chips (2),

- Each light source (1) is followed by an optical body (3) of an optical element (5), and

- The optical body (3) are adapted to guide electromagnetic radiation to a light exit surface (4) of the optical element (5).

2. Light emitting module (20) according to the preceding claim, wherein at least one of the optical body (3) comprises a non-imaging optical concentrator.

3. Light emitting module (20) according to at least one of the preceding claims, wherein at least one of the optical body (3) comprises a truncated pyramidal optic (3a).

4. Light emitting module (20) according to at least one of the preceding claims, wherein at least one of the optical body (3) comprises an asymmetric truncated pyramidal optics.

5. Light emitting module (20) according to at least one of the preceding claims, wherein at least one of the optical body (3) is formed as a solid body.

6. Light emitting module (20) according to at least one of the preceding claims, wherein the optical element (5) is formed in several pieces.

7. Light emitting module (20) according to at least one of the preceding claims, wherein the optical element (5) is integral.

8. Light-emitting module (20) according to at least one of the preceding claims, in which the light exit surface (4) of the optical element (5) is formed by a convex surface (15) extending over the light exit surfaces (40) of the optical body (3). extends.

9. Light emitting module (20) according to at least one of the preceding claims, wherein the light exit surface (4) of the optical element (5) convex portions (15) which are interconnected by concave portions (16).

10. Light emitting module (20) according to at least one of the preceding claims, wherein the light exit surface (4) of the optical element (5) has convex portions (15) which are interconnected by flat surfaces.

11. Light emitting module (20) according to at least one of the preceding claims, wherein the light exit surface (4) of the optical element (5) from the light exit surfaces (40) of the optical body (3) is composed.

12. A light-emitting module (20) according to at least one of the preceding claims, wherein a light entry surface (14) of at least one of the optical bodies (3) has an anti-reflection coating comprising a dielectric material.

13. Light emitting module (20) according to at least one of the preceding claims, wherein the light entry surface (14) of at least one of the optical body (3) has a periodic microstructure, which is adapted to reduce the reflection of electromagnetic radiation.

14. A light emitting module (20) according to at least one of the preceding claims, wherein the light exit surface (4) of the optical element (5) has an anti-reflection coating comprising a dielectric material.

15. Light emitting module (20) according to at least one of the preceding claims, wherein the light exit surface (4) of the optical element (5) has a periodic microstructure, which is adapted to reduce the reflection of electromagnetic radiation.

16. Light emitting module (20) according to at least one of the preceding claims, wherein at least one LED chip (2) is non-poured.

17. Light emitting module (20) according to at least one of the preceding claims, wherein between a light output surface of at least one LED chip (2) and a light entrance surface (14) of an optical body (3), a gap is arranged, which contains air.

18. Light-emitting module (20) according to at least one of the preceding claims, wherein the distance between the light output surface of at least one LED chip (2) and the light entry surface (14) of an optical body (3) is at most 250 microns.

19. Light emitting module (20) according to at least one of the preceding claims, with a holder (13) on which the optical body (3) are fixed.

20. A light-emitting module (20) according to at least one of the preceding claims, wherein the optical body (3) are integrally connected to the holder (13).

21. Light emitting module (20) according to at least one of the preceding claims, wherein the holder (13) surrounds the optical body (3) of at least four sides.

22. A light emitting module (20) according to at least one of the preceding claims, wherein the holder (13) surrounds the light sources (1) of at least four sides.

23. An optical projection apparatus having a light-emitting module (20) according to at least one of the preceding claims and a projection optics (32) which is arranged downstream of the light-emitting module (20).