Patent Application
20080084694
Like, similar, and like-acting elements are provided with the same respective reference characters in the figures. The figures are all schematic representations and therefore are not necessarily true to scale. Rather, small elements may be depicted as exaggeratedly large for purposes of better understanding.
The first exemplary embodiment of an LED arrangement 1, illustrated schematically in
Attached to the carrier 2 is a plurality of light-emitting diodes 3, preferably three or more light-emitting diodes, particularly preferably six or more light-emitting diodes (nine light-emitting diodes are depicted by way of example). The carrier 2 can be rigid or flexible, and is further preferably implemented as a connecting carrier, for example as a circuit board, preferably a printed circuit board (PCB). Carrying this further, the connecting carrier can be implemented as a metal-core circuit board. The light-emitting diodes 3 are expediently configured as surface-mountable components and, on the connecting carrier, are electrically conductively connected to connecting leads, for example by gluing or soldering. This simplifies the mounting of the light-emitting diodes.
Specular or reflective elements that can be used to further influence the radiation characteristic of the LED arrangement (not explicitly illustrated) can additionally be configured in or on the carrier 2.
The radiation characteristic of the LED arrangement 1 can further be adjusted, particularly in the case of a flexible carrier 2, by curving the carrier 2.
The LED arrangement preferably includes light-emitting diodes for generating mixed-color light, particularly light that appears white to the human eye, for example in three primary colors such as red, green and blue.
Each of the light-emitting diodes 3 comprises a similar optical element 4 and an LED component 5. The optical element 4 is implemented as a separately prefabricated optical element, particularly as a lens, which is attached to the LED component 5. Where appropriate, the optical element can also be implemented as a reflector integrated into the LED component or as a combination of such a reflector with a lens (not shown). The present optical element 4 has a radiation exit face 40.
The optical element 4, as viewed from outside the element, can be configured with a radiation exit face 40 that is convexly curved, preferably continuously.
The optical element further has a first marked axis 45 and a second marked axis 46. Each radiation exit face can in particular be implemented as curved in sections taken along these marked axes.
The optical element 4 is implemented such that each of the light-emitting diodes 3 has a non-rotationally-symmetrical radiation characteristic.
The radiation characteristic can be determined, for example, by the dependence of the intensity of the radiation from the light-emitting diode on the angle formed with the optical axis. The optical axis 7 preferably extends through an LED chip 6 of the particular light-emitting diode 3. Particularly preferably, the optical axis 7 extends through a central region of radiation exit face 40. The optical axis can in particular extend perpendicularly to the surface of the LED chip 6 facing toward the optical element 4, and preferably perpendicularly to the radiation exit face 40.
The present optical element 4 is implemented as elongate, for example with a radiation exit face 40 that is ellipsoidal in plan. The long principal axis a can be 1.5 times or more as long, preferably twice or more as long, particularly preferably three times or more as long, at most preferably four times or more as long, than the short principal axis b of the ellipsis.
With the use of such an optical element 4, a radiation characteristic that has no rotational symmetry with respect to the optical axis 7 can be formed by beam-shaping or refracting the radiation generated in the LED chip 6. The LED chip expediently has an active region for generating radiation. Moreover, the LED chip, particularly the active region, contains a III-V semiconductor material. III-V semiconductor materials are particularly suitable for generating radiation in the ultraviolet (InxGayAl1-x-yN) through the visible (InxGayAl1-x-yN especially for blue to green radiation, or InxGayAl1-x-yP, especially for yellow to red radiation) to the infrared (InxGayAl1-x-yAs) regions of the spectrum. In each of the foregoing cases, 0≦x≦1, 0≦y≦1 and x+y≦1, particularly with x≠1, y≠1, x≠0 and/or y≠0. In addition, advantageously high internal quantum efficiencies can be achieved when radiation is generated using III-V semiconductor materials, particularly from the aforesaid material systems. The optical element preferably contains a synthetic material, particularly a synthetic material from the group consisting of thermoplastic, duroplastic and silicone.
Alternatively or supplementarily, the optical element can contain a resin, particularly a resin from the group consisting of epoxy resin, acrylic resin and silicone resin.
An elongate, particularly ellipsoid-like, illuminance distribution can therefore be produced on a to-be-illuminated surface extending parallel to the carrier 2 if said surface is illuminated by means of a single light-emitting diode 3.
Despite the breaking of rotational symmetry, the radiation characteristic of the light-emitting diode can extend axially symmetrically to the optical axis. The illuminance distribution of the individual light-emitting diode on the surface to be illuminated then does not exhibit any islands of increased radiant power located away from the optical axis.
The radiation characteristic of the LED arrangement 1 is obtained by superimposing the radiation emitted by the individual light-emitting diodes 3.
If some or all of the optical elements 4 are arranged with the direction of longitudinal extent (for example, long main axis a) oblique, i.e. at an angle different from 0° and in particular also different from 90°, to an edge 20 of the carrier 2, then defined radiation characteristics for the LED arrangements, and thus also a defined illuminance distribution on a surface to be illuminated, can be obtained in a simplified manner.
The individual optical elements 4 are arranged rotated with respect to the carrier 2, which in particular is planar. The direction of rotation preferably extends azimuthally to the optical axis 7.
According to
The optical elements 4 of the corner light-emitting diodes are each rotated in their direction of longitudinal extent relative to the direction of longitudinal extent of the optical element 4 of an adjacent light-emitting diode (cf., for example, intermediate angle 8). The inner optical elements 4 are oriented in parallel in the longitudinal direction, particularly parallel to the carrier edge 20.
Diagonally opposite optical elements are arranged with their longitudinal directions parallel. Any decrease in the illuminance distribution toward the edges of the surface to be illuminated by the LED arrangement 1 can be reduced in this way. Homogeneous illumination of a surface is thereby simplified.
The light-emitting diode 3 includes an LED component 5 comprising a housing 55. The LED chip 6 is disposed in a cavity 56 of the housing 55. A wall 57 of the cavity 56 forms a reflector. Such a wall is implemented as reflective of the radiation generated in the LED chip. To increase reflection, the wall can be provided with a coating if necessary. Radiation generated in the LED chip can be reflected from the wall 57 and deflected in the direction of the radiation exit face 40 of the optical element.
The reflector configured in the LED component 5 can be implemented as rotationally symmetrical to the optical axis. A radiation characteristic that has no rotational symmetry can also be formed by means of the correspondingly shaped optical element 4. However, the reflector can also be shaped so as to result in, or at least be conducive to, a radiation characteristic that breaks rotational symmetry. For example, the reflector can have a basic shape in plan that deviates from a circular shape, for instance an elliptical shape. An optic with a radiation characteristic that breaks rotational symmetry can therefore also be obtained by means of a reflector or a combination of a reflector with a lens.
The LED component comprises a contact lead 51 and a further contact lead 52, each of which is electrically conductively connected respectively to a terminal area 21 and to a further terminal area 22 on the carrier 2, for example via an electrically conductive connecting means 59, such as a solder. The contact leads 51, 52 are electrically conductively connected to the LED chip, it being possible to establish the electrically conductive connection of contact lead 51 by means of a bond wire 53.
Particularly to protect against external influences, such as moisture, the LED chip 6 and, if present, the bond wire 53 can be embedded in an encapsulant 56.
In
Furthermore, in deviation from the illustrated exemplary embodiment, the optical element can project at least regionally outward laterally beyond the LED component 5, particularly beyond the housing 55.
In a method for producing an LED arrangement 1, a desired radiation characteristic can first be defined for the LED arrangement. A multiplicity of light-emitting diodes 3 having similar radiation characteristics can be prepared, with the radiation characteristic of each of the light-emitting diodes exhibiting a broken rotational symmetry. A suitable number and a suitable arrangement of the light-emitting diodes for the desired radiation characteristic can then be determined. For example, by increasing the number of light-emitting diodes, it is possible to increase the overall radiant power of the LED arrangement. The previously determined suitable number of light-emitting diodes, in the previously determined arrangement, can be disposed on and in particular attached to a carrier 2 for the LED arrangement. The radiation characteristic can be adjusted in particular by suitably orienting the light-emitting diodes 3, i.e. by rotating the light-emitting diodes 3 relative to one another or relative to a carrier edge 20. The light-emitting diodes 3 can be attached to the carrier 2, for example by soldering or gluing, in the provided position and orientation.
LED arrangements produced and finished according to this method can be implemented as described in connection with
LED arrangements whose radiation is matched to a defined desired radiation characteristic can also be produced in a simple manner by the described method.
The directions of longitudinal extent of the light-emitting diodes 3 in the outer columns extend parallel to one another. The directions of longitudinal extent of the light-emitting diodes in the center column extend parallel to a carrier edge 20 of the carrier 2.
Naturally, another arrangement and/or orientation of the directions of longitudinal extent of the optical elements 4 may be appropriate for the light-emitting diodes, depending on the defined radiation characteristic of the LED arrangement. A defined radiation characteristic of the LED arrangement 1 can be obtained in a simple manner by combining a suitable number of light-emitting diodes 3 and a suitable oblique position for the elongate optical elements 4 relative to one another and/or to the carrier edge 20.
Additional embodiments are within the scope of the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2006 047 233.0 | Oct 2006 | DE | national |
This application claims priority under 35 U.S.C. 119(a) to German Patent Application 10 2006 047 233.0 filed Oct. 4, 2006 and also claims priority under 35 U.S.C. 119(e) to U.S. Provisional Application No. 60/860,943 filed Nov. 24, 2006, the contents of said applications are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 60860943 | Nov 2006 | US |
| Child | 11862429 | US |
