Asymmetric linear LED luminaire design for uniform illuminance and color
An LED lamp for illuminating a surface under a flat angle in linear lighting applications such as cove lighting and wall washing is provided. It produces a uniform intensity distribution and a uniform color output throughout the beam pattern of the light beam produced by a multi-color LED light source. The lamp comprises a body of an extruded profile. The body comprises at least one section with a mirrored surface and at least a lens section which allows exiting of light from the body. At least one LED preferably having a LED lens is provided at the inner side of the body. This combination of optical systems results in an asymmetric beam pattern from the source.
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The present application is a reissue of U.S. Pat. No. 9,458,972, issued on Oct. 4, 2016 from U.S. application Ser. No. 14/516,818, filed Oct. 17, 2014, which is hereby incorporated by reference herein in its entirety.
BACKGROUND OF THE INVENTION1. Field of the Invention
The invention relates to a LED lamp and color mixing optics for illuminating a surface under a flat angle. The LED lamp produces a uniform intensity distribution and a uniform color output throughout the beam pattern of the light beam produced by a multi-color LED light source.
2. Description of Relevant Art
In linear lighting applications such as cove lighting and wall washing, it is desired to shape the beam of a lamp to achieve a uniform color and illuminance distribution on a target architecture surface, which may be a wall or a ceiling. As the illuminance incident on the target decreases as a function of the inverse of the light travelling distance (inverse-square law), the light intensity distribution from the lamp should be highly asymmetric. For example, a fluorescent pendant light which has a symmetric beam shape would illuminate the upper wall much brighter than the lower wall.
Color LED lamps should have an even intensity and color distribution over a broad range of radiation angles. As there is no single point LED source available, the radiation of multiple LED sources must be combined to form a multi-color light source. These multiple LED sources are placed offset to each other, so there is no common focal point. To obtain an even color distribution, color mixing is required.
Another important factor impacting the illumination uniformity is the setback distance, which is defined as the perpendicular distance between the luminaire aperture and the target surface. A small setback distance is usually preferred by lighting and architecture designers, but too short distance may reduce the uniformity, resulting in bright spots on the target plane.
U.S. Pat. No. 8,529,102 discloses a reflector system for a multi-color LED lamp providing color mixing. The system uses two reflective surfaces to redirect the light before it is emitted.
US Publication No. 2007/0171631 discloses LED cove lighting comprising a large and complex aluminum mirror system to obtain a uniform light distribution at a wall.
SUMMARY OF THE INVENTIONThe embodiments are based on the object of making a LED lamp and a color mixing optic for color LED lamps which produces uniform intensity and color throughout the entire light beam when illuminating a surface under a flat angle. Furthermore, the optic should be simple, robust as well as easy and cost-effective to manufacture. The setback distance should be small compared to the length of the surface. Another embodiment is based on the object of making a color LED lamp comprising the color mixing optic.
In an embodiment, a lamp comprises a body which may further comprise a profile, preferably a hollow profile or an extruded profile. The body preferably comprises at least one section with a mirrored surface and at least a lens section which allows exiting of light from the body. At least one LED preferably having a LED lens is provided at the inner side of the body. This combination of optical systems results in an asymmetric beam pattern from the source.
At least one LED, preferably a plurality of LEDs are mounted on a LED mounting plane. It is mounted on a preferably planar mounting surface which preferably extends in a plane defined by the direction of extrusion. Preferably, a plurality of LEDs is aligned on a common center line, which preferably extends into the direction of extrusion. This mounting surface may comprise a printed circuit board or any other means for holding the at least one LED and preferably further electronic components. This embodiment relates to a color LED lamp and therefore requires multicolor LED emitters. These are preferably different LED chips combined to generate a plurality of visible colors. Herein, reference is made to a LED which means a plurality of LED chips for generating the different colors. Preferably, each LED is covered by a LED lens which preforms the beam pattern emitted by the LED and which further may protect the LED.
Close to the LED lens, the mirrored surface of the body has at least one paraboloidal section, preferably two paraboloidal sections. Preferably, at least one of the paraboloidal section has its focus line which is coincident with the LED center line. If a plurality of paraboloidal sections is provided, preferably at least two of these sections have the same focal length, and most preferably have the same focal line which is further preferably coincident with the LED center line. The paraboloidal sections deflect most of the light emitted by the at least one LED into a direction which is roughly parallel to the LED mounting plane and which exits the lamp through a first lens forming a first exit surface of the body. It is further preferred that the paraboloidal sections are slightly rotated around the focal line in a plane perpendicular to the direction of extrusion against each other. This results in a slightly different main beam direction of the lamp.
It is further preferred to have at least one arc-shaped reflector. Most preferably, there are three arc-shaped reflectors. These arc-shaped reflectors preferably are next to the at least one paraboloidal section. Preferably, they deflect a further part of the light through a second lens, under an angle which may be any flat angle up to a 90 degree angle to the mounting plane of the LED by means of the arc-shaped reflectors. Another part of the light is reflected towards the first lens.
For capturing residual light, a backside reflector may be provided at one side of the LED oriented towards the prime lens and set back from the mounting plane of the LED.
The embodiments described herein provide a better light distribution on a surface or wall with a reduced setback distance and provide an improved color mixing. The body is made of a robust profile and may be easily manufactured. It provides a fully enclosed housing which protects the LEDs and the inner optics from environmental influences.
In the following, the invention will be described by way of example, without limitation of the general inventive concept, on examples of embodiment and with reference to the drawings.
While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present invention as defined by the appended claims.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTSIn
Most of the light emitted by the LED is deflected by the paraboloidal sections. This light is radiated through a prime lens 56 defining a first exit surface. The prime lens has a lens body 61 and may have a Fresnel-lens like surface structure. The surface may have a plurality of slopes which define the light distribution at the output of the lamp. The light deflected by the arc-shaped reflectors 53, 54, and 55 is guided through an outside lens 62 forming a second exit surface of the lamp. Finally, there is a backside reflector 63 which is reflecting light rays back to the interior of the lamp.
The LED base plane, the paraboloidal sections, the arc-shaped reflectors, the lens body, the outside lens, and the backside reflector enclose the inner volume of the lamp. They form an elongated body which may be closed at its end by others, which may only be protective covers which may also have a reflective inner surface. At least one or all of the reflective surfaces in the lamp may be total reflecting surfaces or may be mirrored surfaces (or other reflecting coated surface) or a combination thereof.
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The embodiment shown herein provides a good color mixing of the light generated by a plurality of LED emitters, herein referred to as LED 41, which are mounted under a lens 42, and provides a uniform light distribution over a surface, like a wall.
It will be appreciated to those skilled in the art having the benefit of this disclosure that this invention is believed to provide optics for LED lighting with color mixing properties. Specifically, color mixing optics are disclosed herein for producing a uniform intensity distribution and a uniform color distribution throughout the entire beam pattern produced by a multi-color LED light source. Further modifications and alternative embodiments of various aspects of the invention will be apparent to those skilled in the art in view of this description. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the general manner of carrying out the invention. It is to be understood that the forms of the invention shown and described herein are to be taken as the presently preferred embodiments. Elements and materials may be substituted for those illustrated and described herein, parts and processes may be reversed, and certain features of the invention may be utilized independently, all as would be apparent to one skilled in the art after having the benefit of this description of the invention. Changes may be made in the elements described herein without departing from the spirit and scope of the invention as described in the following claims.
Claims
1. A An LED lamp for illuminating a surface comprising:
- a body further comprising:;
- a plurality of multi-color LED light sources;
- a spherical cap lens covering each of the plurality of multi-color LED light sources and having a radius that is larger than a radius of a base of the spherical cap lens;
- wherein the spherical cap lens further comprising comprises a plurality of spherical cap lenses covering respective ones of the plurality of multi-color LED light sources, and wherein each of the plurality of multi-color LED light sources and each of the plurality of spherical cap lenses covering respective ones of the plurality of multi-color LED light sources are arranged distant to each other on a an LED mounting plane and are aligned with their centers to a common center line with at least one paraboloidal section having its focus at the common center line of the plurality of multi-color LED light sources;
- at least one section with a mirrored surface, for reflecting the light emitted by the at least one plurality of multi-color LED light source sources, the mirrored surface section further comprising the at least one paraboloidal section and at least one convex arc shaped reflector reflective surface; and
- at least one lens section forming an exit surface for the light, the at least one lens section comprising a prime lens for a main beam direction and an outside lens for an auxiliary beam direction; and
- wherein the at least one arc shaped reflector deflects parts of the light emitted by the plurality of multi-color LED light sources to the outside lens and other parts of the light to the prime lens.
2. The LED lamp of claim 1, wherein the body comprises a hollow profile.
3. The LED lamp of claim 1, wherein the body comprises an extruded profile.
4. The LED lamp of claim 1, wherein the body further comprises a backside reflector arranged behind a mounting plane of the plurality of multi-color LED light sources.
5. The LED lamp of claim 1, wherein the plurality of multi-color LED light sources, each comprising a plurality of LED chips.
6. The LED lamp of claim 1, wherein the mirrored surface is a total reflecting surface or a reflecting coated surface.
7. The LED lamp of claim 1, wherein the at least one paraboliodal section comprises a plurality of paraboloidal sections are provided being slightly rotated against each other.
8. The LED lamp of claim 1, wherein the at least one lens section comprises a Fresnel lens like structure.
9. The LED lamp of claim 1, wherein the at least one lens section comprises a prime lens for a main beam direction and an outside lens for an auxiliary beam direction is provided.
10. The LED lamp of claim 9, wherein the at least one arc shaped reflector deflects parts of the light emitted by the at least one multi-color LED light source to the outside lens and other parts of the light to the prime lens.
11. An LED lamp for illuminating a surface comprising:
- a body;
- an LED light source;
- a semi-sphere lens covering the LED light source, wherein the LED light source is located at a center of the semi-sphere lens;
- at least one lens section forming an exit surface for light emitted by the LED light source, wherein the at least one lens section comprises a prime lens defining a first exit surface for a main beam direction and an outside lens defining a second exit surface for an auxiliary beam direction; and
- at least one side wall comprising a mirrored surface located such that the mirrored surface receives a portion of the light emitted by the LED light source, the mirrored surface further comprising at least one paraboloidal section and at least one arc shaped reflector, wherein the at least one arc shaped reflector deflects parts of the portion of the light emitted by the LED light source to the outside lens and other parts of the portion of the light emitted by the LED light source to the prime lens.
12. The LED lamp of claim 11, wherein the body comprises a hollow profile.
13. The LED lamp of claim 11, wherein the body comprises an extruded profile.
14. The LED lamp of claim 11, wherein the mirrored surface is a total reflecting surface or a reflecting coated surface.
15. The LED lamp of claim 11, wherein the at least one paraboloidal section comprises a plurality of paraboloidal sections rotated against each other.
16. An LED lamp for illuminating a surface comprising:
- a body;
- a plurality of LEDs on a first plane and aligned on a common center line and configured to emit light;
- a spherical cap lens covering each of the plurality of LEDs and having a radius that is larger than a radius of a base of the spherical cap lens;
- a first side wall paraboloidal section configured to deflect first light rays emitted from the plurality of LEDs through a first section of a first lens;
- a second side wall paraboloidal section configured to deflect second light rays emitted from the plurality of LEDs through a second section of the first lens;
- a first side wall arc shaped reflector configured to deflect third light rays emitted from the plurality of LEDs towards a backside reflector;
- a second side wall arc shaped reflector configured to deflect fourth light rays emitted from the plurality of LEDs through a first section of a second lens; and
- a third side wall arc shaped reflector configured to deflect fifth light rays emitted from the plurality of LEDs through a second section of the second lens;
- wherein the first, second, and third side wall arc shaped reflectors are adjacent to the first and second side wall paraboloidal sections.
17. The LED lamp of claim 16, wherein the body comprises a hollow profile.
18. The LED lamp of claim 16, wherein the body comprises an extruded profile.
19. LED lamp of claim 16, wherein the plurality of LED light sources each comprises a plurality of LED chips.
20. The LED lamp of claim 16, wherein the first side wall paraboloidal section and the second side wall paraboloidal section are rotated against each other.
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Type: Grant
Filed: Oct 4, 2018
Date of Patent: Jan 4, 2022
Assignee: Lutron Technology Company LLC (Coopersburg, PA)
Inventors: Fangxu Dong (Austin, TX), An Mao (Austin, TX)
Primary Examiner: James A Menefee
Application Number: 16/152,106
International Classification: F21V 9/00 (20180101); F21V 7/00 (20060101); F21V 5/04 (20060101); F21S 8/00 (20060101); F21V 7/06 (20060101); F21V 5/00 (20180101); F21V 7/22 (20180101); F21K 99/00 (20160101); F21K 9/60 (20160101); F21V 7/28 (20180101); F21S 8/04 (20060101); F21Y 113/13 (20160101); F21Y 103/10 (20160101); F21Y 115/10 (20160101); F21Y 101/00 (20160101);