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Researchers Submit Patent Application, "Led Luminaires Based on Color Mixing and Remote Phosphor Arrangement", for Approval

September 10, 2014



By a News Reporter-Staff News Editor at Electronics Newsweekly -- From Washington, D.C., VerticalNews journalists report that a patent application by the inventors Chen, Peng (Shenzhen, CN); Li, Aiai (Shenzhen, CN); Liu, Tingming (Shenzhen, CN); Zheng, Shengmei (Shenzhen, CN), filed on August 9, 2012, was made available online on August 28, 2014.

The patent's assignee is Osram Gmbh.

News editors obtained the following quote from the background information supplied by the inventors: "In recent years, there are a lot of LED (light emitting diode) based luminaires available for various applications like home, shop, street, office, etc. As compared with traditional fluorescent lamps, the LED based luminaires can provide much longer lifetime, higher energy efficiency, and are more environment-friendly.

"However, these white LED-based luminaires are still facing a few difficulties that prevent them from more popular uses. The issues include light distribution uniformity, color rendering ability, color stability, efficiency and cost, etc.

"In particular, the color rendering indexes (CRI) of the LEDs are usually low, typically in the range of 70-80 for cool white, and 80-90 for warm white.

"For example, the existing white LED T8 tube with a transparent cover usually has a CRI of 70-80, and has disadvantages of spotty light distribution and heating-caused color shift.

"To improve the color rendering, color mixing is usually used. However, for conventional 'white LED+red' color mixing approach, it is difficult to control the color uniformity.

"Complicated circuit design is usually needed, and there is color shift due to different thermal-induced degradation behaviors of different types of phosphors (such as yellow phosphor in the white LED and red phosphor).

"In addition, the exiting color mixing technique has the following disadvantages:

"Mixed color is not uniform and may have bright color spots when there is lack of enough distance to mix the light in the luminaires;

"Low light emitting efficiency is caused when a diffusive cover is used to improve light distribution uniformity; and Heating-induced color shift.

"As illustrated in FIG. 1A, when a distance between a diffusive fluorescence component and light emitting elements 110, 120 is smaller than d, light emitted from the light emitting elements 110 and 120 reaches the diffusive fluorescence component without mixing, such that bright color spots illustrated in FIG. 1B are generated, and the color and brightness uniformity of the luminaires are influenced. In the Figures, .alpha. is representative of light divergence angle of the light emitting elements, and L is representative of a distance between adjacent light emitting elements."

As a supplement to the background information on this patent application, VerticalNews correspondents also obtained the inventors' summary information for this patent application: "Various embodiments provide a luminaire capable of providing improved color rendering, and maintaining uniform light mixing. In various embodiments, a luminaire is provided, the luminaire including: two or more groups of light emitting elements, each group of light emitting elements having respective wavelength range; and a fluorescence component capable of generating fluorescence under excitation of light emitted from the light emitting element, wherein, the fluorescence component is spaced apart from the light emitting elements in the light propagation direction of the light emitting element, and light of each group of light emitting elements is combined with the fluorescence into white light.

"In one embodiment of the disclosure, the two or more groups of light emitting elements form an array with a predetermined amount ratio in an interleaving manner.

"In one embodiment of the disclosure, the fluorescence component is a cylinder component provided surrounding the light emitting element array.

"In one embodiment of the disclosure, the two or more groups of light emitting elements include blue light emitting diode and red light emitting diode, and the fluorescence component has yellow phosphor.

"In one embodiment of the disclosure, the amount ratio of the blue light emitting diode to the red light emitting diode is 3:1.

"In one embodiment of the disclosure, the two or more groups of light emitting elements include mint light emitting diode and amber light emitting diode.

"In one embodiment of the disclosure, a distance d that the fluorescence component spaces apart from the light emitting elements satisfies:

"d > L 2 cot .alpha. 2 ##EQU00001##

"wherein, L is a distance between adjacent light emitting elements, and .alpha. is a light divergence angle of the light emitting element.

BRIEF DESCRIPTION OF THE DRAWINGS

"In the drawings, like reference characters generally refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the disclosed embodiments. In the following description, various embodiments described with reference to the following drawings, in which:

"FIG. 1A is a schematic view illustrating a light emitting path of an LED for color mixing;

"FIG. 1B is an effect view of bright color spot present when the color mixing distance is smaller than the distance d illustrated in FIG. 1A;

"FIG. 2A is a perspective view illustrating a configuration example of the luminaires according to an embodiment of the invention;

"FIG. 2B is a partial cross sectional view illustrating the luminaires illustrated in FIG. 2A;

"FIGS. 3A and 3B are spectrum diagrams of the blue LEDs and red LEDs used in the exemplary embodiments of the disclosure, respectively;

"FIGS. 4A and 4B are the phosphor emission spectrum and the distribution diagram of the phosphor powder particle size of the yellow phosphor powder used in the exemplary embodiment of the disclosure, respectively;

"FIG. 5A illustrates the spectrum of the white light obtained by color mixing in the remote phosphor arrangement according to the exemplary embodiment of the disclosure;

"FIG. 5B illustrates the position of the white light obtained by color mixing in the remote phosphor arrangement according to the exemplary embodiment of the disclosure in the CIE chromaticity diagram;

"FIG. 6A is a perspective view illustrating a configuration example of the luminaire having a down light configuration according to another embodiment of the disclosure; and

"FIG. 6B is a section view illustrating the luminaire illustrated in FIG. 6A."

For additional information on this patent application, see: Chen, Peng; Li, Aiai; Liu, Tingming; Zheng, Shengmei. Led Luminaires Based on Color Mixing and Remote Phosphor Arrangement. Filed August 9, 2012 and posted August 28, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=4484&p=90&f=G&l=50&d=PG01&S1=20140821.PD.&OS=PD/20140821&RS=PD/20140821

Keywords for this news article include: Electronics, Light-emitting Diode, Osram Gmbh.

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Source: Electronics Newsweekly


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