JP2003209288A - Led illumination system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an LED illumination system with which a surface can be illuminated with a predetermined homogenous illumination intensity distribution, and which has a simple construction and is inexpensive to produce. <P>SOLUTION: In the LED illumination system between at least one LED element and the surface to be illuminated, an illumination optical system which deflect emitted light asymmetrically relative to the main beam direction of the LED element is arranged. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LED lighting system for illuminating a surface with a predetermined illumination intensity distribution, the LED lighting system having at least one LED element that emits light particularly symmetrically with respect to a main emission direction of the LED element.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication (Kokai) No. 2004-242242 discloses an illuminating device having a plurality of light sources and one light guide which guides the emitted light along its longitudinal direction and emits it to an object to be illuminated. . The emitting surface of the light guide is embodied in the form of a lens, so that relatively high intensity light can be focused at the location of the illuminated object.

Illumination devices of this kind are suitable for illuminating an object which is more or less expansive, for example for illuminating the object for scanning or copying. The light is therefore focused as broadly as possible on the object so that the required illumination can be provided with a minimum amount of light.

On the other hand, different illumination systems are used to illuminate a wide area. For this purpose, the illumination system must be able to illuminate the illuminated surface with a certain predetermined illumination intensity distribution. For example, the text or color representation on the illuminated surface may be extensive so that the reading of the text is not unduly disturbed or that a color difference that does not actually exist is present in the color representation. Surface needs to be uniformly illuminated.

However, conventional lighting systems give unsatisfactory results, or their construction is costly and expensive.

[0006]

[Patent Document 1] EP-A-1 017 222

[0007]

An object of the present invention is to illuminate a surface to be illuminated with a predetermined illumination intensity distribution, in particular with a uniform illumination intensity distribution, and also to have a simple structure and at a low cost. To provide an LED lighting system of the type mentioned at the outset which can be manufactured.

[0008]

SUMMARY OF THE INVENTION The above-mentioned problem is that an illumination optical system is provided between at least one LED element and a surface to be illuminated, which deflects emitted light asymmetrically with respect to the main emission direction of the LED element. Is solved by the existing LED lighting system.

[0009]

According to the invention, in an LED lighting system, the emitted light is deflected asymmetrically with respect to the main emission direction of the LED semiconductor, between at least one LED semiconductor body and the illuminated surface. An illumination optical system is arranged.

The asymmetric deflection is independent of the shape of the surface,
It is possible to adjust the illumination of the surface that suits the purpose. therefore,
Due to the asymmetrical deflection of symmetrically emitted light in a surface of arbitrary shape, it is possible to account for a variable distance from the light source to a point on the surface and a variable angle at which the light ray strikes the surface.

In one embodiment, the illumination system is defined to accommodate uniform illumination of the surface. In particular, the illumination system may be adapted for uniform illumination of curved surfaces, in particular for convex or concave illumination.

However, it is also possible to use the illumination system in a targeted manner for non-uniform illumination of the surface. For example, it may be used to optically enhance or obscure a given surface area.

In an advantageous embodiment, the illumination optics are formed by one or more lens elements. If the illuminated surface is, for example, concave when viewed from the side of the lens element, the lens element has, for example, a concave surface in the direction of the LED and a convex surface in the direction of the illuminated surface.

However, advantageously, the corresponding illumination optics is 1
It may be formed by one or a plurality of Fresnel lenses.

In an advantageous embodiment, the lighting system comprises a plurality of LED semiconductor bodies emitting in different spectral regions.

In this regard, the following embodiments are particularly practical. That is, an embodiment is provided in which the light of the LED semiconductor bodies emitted in the various spectral regions complement each other into white light, for example three LED semiconductor bodies, from which the red and green LED semiconductor bodies are emitted. And embodiments in which blue light is emitted are particularly practical.

Advantageously, the one or more LED semiconductor bodies are GaN semiconductor material, InGaN semiconductor material, Al
GaN semiconductor material, InAlGaN semiconductor material, ZnS
It includes a semiconductor material, a ZnSe semiconductor material, a CdZnS semiconductor material, or a CdZnSe semiconductor material, and emits visible light, infrared electromagnetic radiation, or ultraviolet electromagnetic radiation depending on the purpose.

In an alternative, one or more, which is arranged in radial direction behind the semiconductor body and is preferably arranged between the semiconductor body and the lens, for producing white light in the illumination system. A plurality of luminescence conversion elements are used. For this, for example, in the case of a semiconductor body emitting blue light, a luminescence conversion element is suitable which converts part of the blue light into yellow light or green light or red light and mixes it with the blue light of the semiconductor body.

In one embodiment, the LED semiconductor body and the illumination optics form an illumination module and are located in a common module housing.

The wall of the module housing may be formed by a Fresnel lens which is a constituent member of the illumination optical system. Of course, this Fresnel lens may be the only lens required for the illumination optical system. In that case, a particularly simple and compact construction of the illumination system is obtained.

Further advantageous embodiments, features and details of the invention are apparent from the dependent claims, the description of the examples and the drawings.

Hereinafter, the present invention will be described in more detail based on embodiments with reference to the drawings. In each case, only those elements that are important to the understanding of the invention are shown.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An LED lighting system 1 according to the embodiment shown schematically in cross section in FIG. 1 is for uniform illumination over a large area of a curved surface 5, for example. The curved surface 5 is, for example, a graph.

The LED element 2 mounted on the support emits the light required for illumination during operation. If the emitted light is not corrected, it will be immediately apparent to the expert that a uniform illumination of the curved surface 5 cannot be obtained for several reasons.

First, the radiation characteristic of the LED element 2 is not constant over the entire solid angle Ω occupied by the curved surface 5,
It has the maximum intensity in the angular region around the main radiation direction 9. Secondly, the distance from the LED element 2 to the curved surface 5 is variable, and thirdly, with the curvature of the surface 5 along the expansion in the longitudinal direction, the incident angle of the light ray striking the surface also changes.

Nevertheless, in order to achieve a uniform illumination of the curved surface 5 over a wide area, the emitted light is correspondingly provided as an illumination optical system between the curved surface 5 and the LED element 2 with respect to the main emission direction 9 of the LED element 2. A lens 4 is arranged which asymmetrically deflects.

The intensity distribution of the emitted light from the LED element 2, represented as a geometrical ray 6 by the arrow in FIG.
It is at least approximately symmetrical about the main radiation direction 9.
The illumination optical system 4 deflects the light ray 6 so that the light ray 6 strikes the curved surface 5 as a light ray 8 having an asymmetric distribution. For this reason, the illumination optical system 4 is a lens 4 having an asymmetrical shape,
The surface 41 facing the LED element 2 is concave, and the surface 42 facing the curved surface 5 is convex, for example, parabolic convex.

The degree of deflection is determined in such a way that the above-mentioned effect and, in some cases, other effects which lead to uneven illumination of the curved surface 5 are compensated, so that the surface of the curved surface 5 is uniform. Lighting intensity is generated. This compensation is done, for example, by selecting the curvatures of the outer lens surface 42 and the inner lens surface 41, as is known per se in the prior art.

The overall construction of the LED element 2 and the illumination optics 4 is preferably housed in a common module housing.

The embodiment of FIG. 1 has one LE for simplicity.
Although depicted as having only D elements 2, it is clear to the expert that instead of just one LED element, multiple LED elements may be provided in the lighting system. In particular, the LED element can be made to emit colors of different spectra in order to obtain the desired color impression on the emitting surface 5.

This is implemented in the lighting system 11 of FIG. 2 which illustrates another embodiment of the present invention. 3 LEs
The D elements 12a, 12b, and 12c have red (650 nm) and green (530n) so that white light is emitted as a whole.
m) to the blue (470 nm) spectral region. Alternatively, for the emission of white light, blue light emitting diodes may be used with conversion materials that convert blue light into longer wavelength radiation.

The three LED elements 12a-c are mounted on a support 3 and, like the illumination system 1, are shown in FIG.
It is designed to illuminate surfaces not shown in.

The illumination optical system for producing the desired illumination intensity on the surface to be illuminated is formed by the Fresnel lens 14 in this embodiment. By dividing the Fresnel lens 14 into radial zones of approximately the same maximum thickness, a very flat lens is achieved.

This allows the Fresnel lens 14 to form the wall of the module housing 17, allowing a compact and independent illumination system to be implemented. Also, the Fresnel lens 14 can simply be replaced by a correspondingly adapted Fresnel lens when other distribution patterns of illumination intensity are desired.

Commercially available surface-mountable LED elements are used as the LED elements 2 and 12a to 12b which are advantageous for the above-described embodiments and the present invention in general. FIG. 3 schematically shows such an LED device. In this figure, L
At least one LED semiconductor body 20 is arranged in each ED plastic housing 21. Advantageously, the LED semiconductor body 20 is in the reflector 22 of the LED plastic housing 21. The reflection device 2
2 advantageously focuses the light emitted from the LED semiconductor body 20. Instead of or in addition to the reflector 22, a focusing lens 23 may be placed behind the LED semiconductor body 20 in order to focus the light emitted from the LED semiconductor body 20. The focusing lens 23 is preferably L
It is fixed to the ED plastic housing 21.

Alternatively, one or more LED semiconductor chips without a housing may be mounted on the chip carrier 3 as LED elements in the lighting module. However, the module housing 7
For example, in terms of density, higher demands have to be fulfilled than with the use of LED elements with housings as described for example in connection with FIG. 3 above.

[Brief description of drawings]

FIG. 1 schematically shows a cross section of an LED lighting system according to a first embodiment of the present invention.

FIG. 2 schematically shows a cross section of an LED lighting system according to a second embodiment of the present invention.

FIG. 3 schematically shows a cross section of an LED element that is advantageous for use in a lighting system.

[Explanation of symbols]

1 LED lighting system 2 LED element 3 support 4 Illumination optical system 5 Illuminated surface 6 rays 7 Module housing 8 rays 9 Main radiation direction 11 Lighting system 12a to 12c LED element 14 Illumination optical system 17 Module housing 20 LED semiconductor body 21 LED plastic housing 22 Reflector 23 Focusing lens 41 The surface of the lens element facing the LED element 42 The surface of the lens element facing the curved surface Ω Solid angle occupied by curved surface

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI Theme Coat (reference) // F21Y 101: 02 F21S 1/02 G (72) Inventor Joachim Ryle Germany Federal Republic of Germany Zeitrunrun Hauptstraße 40 F Term (reference) 5F041 AA14 CA34 CA40 CA41 CA42 CA43 DB09 EE11 EE25 FF11

Claims (15)

[Claims] 1. An LED illumination system for illuminating a surface (5) with a predetermined illumination intensity distribution, which emits light eg symmetrically with respect to a main emission direction (9) of an LED element (2; 12a-c). At least one LED
In an LED lighting system of the type having elements (2; 12a-c), the emitted light (between the at least one LED element (2; 12a-c) and the surface (5) to be illuminated ( An illumination optical system (4; 1) that asymmetrically deflects 6) with respect to the main emission direction (9) of the LED elements (2; 12a-c).
4) LED lighting system, characterized in that 2. The L according to claim 1, wherein the system is adjusted and determined to illuminate the surface (5) uniformly.
ED lighting system. 3. LED lighting system according to claim 1 or 2, wherein the system is adjusted and determined to illuminate a curved surface (5), for example convex or concave, uniformly. 4. The illumination optical system comprises a lens element (4; 1).
LED lighting system according to any one of claims 1 to 3, which is formed by 4). 5. The surface (41) of the lens element facing the LED element (2) is concave and the surface (42) of the lens element facing the curved surface (5) is convex, eg The LED lighting system according to claim 4, wherein the LED lighting system is parabolic convex. 6. The LED illumination system according to claim 1, wherein the illumination optical system is formed by one or more Fresnel lenses (14). 7. One of said LED elements (2; 12a-c) is a GaN semiconductor material, InGaN semiconductor material, AlGaN semiconductor material, InAlGaN semiconductor material, ZnS semiconductor material, ZnSe semiconductor material, CdZn.
7. The LED lighting system according to claim 1, comprising an S semiconductor material or a CdZnSe semiconductor material. 8. The method according to claim 1, wherein one of the LED elements (2; 12 a-c) emits visible light, infrared electromagnetic radiation or ultraviolet electromagnetic radiation when activated. The described LED lighting system. 9. The system comprises a plurality of LED elements (12a-c) emitting in various spectral regions.
The LED lighting system according to claim 1. 10. LED lighting system according to claim 9, wherein the emitted light of the LED elements (12a-c) is complemented by white light. 11. At least one of the LED elements (2; 12a-c) and the illumination optics form an illumination module and a common module housing (7; 1).
LED lighting system according to any one of claims 1 to 10, arranged in 7). 12. The LED illumination system according to claim 11, wherein the illumination optics comprises a Fresnel lens (14) forming the module housing (17). 13. The LED lighting system according to claim 1, wherein the LED element is a surface-mountable LED element having an LED plastic housing. 14. The LED lighting system of claim 13, wherein the LED plastic housing has a reflector within the LED semiconductor body. 15. LED lighting system according to claim 13 or 14, wherein the LED plastic housing has a focusing lens mounted in the radial direction behind the LED semiconductor body, for example mounted on the LED plastic housing.