Light-emitting devices providing asymmetrical propagation of light

Abstract

A variety of light-emitting devices for general illumination utilizing solid state light sources (e.g., light emitting diodes) are disclosed. In general, the devices include a scattering element in combination with an extractor element. The scattering element, which may include elastic and / or inelastic scattering centers, is spaced apart from the light source element. Opposite sides of the scattering element have asymmetric optical interfaces, there being a larger refractive index mismatch at the interface facing the light emitting element than the interface between the scattering element and the extractor element. Such a structure favors forward scattering of light from the scattering element. In other words, the system favors scattering out of the scattering element into the extractor element over backscattering light towards the light source element. The extractor element, in turn, is sized and shaped to reduce reflection of light exiting the light-emitting device at the devices interface with the ambient environment.

Description

[0001] Cross References to Related Applications [0002] This application claims the benefit of the following provisional applications: Provisional Application No. 61 / 563,513l, filed November 23, 2011; Provisional Application No. 61 / 595,663, filed February 6, 2012; and Provisional Application No. 61 / 700,724, filed September 13, 2012. The entire contents of each of these priority applications are hereby incorporated by reference. technical field [0003] The present invention relates generally to light emitting devices, and in particular, to light emitting devices featuring solid state light emitting elements and scattering elements and extractor elements away from the light emitting elements. Background technique [0004] Light emitting elements are ubiquitous in the modern world, being used in applications ranging from general lighting (eg, light bulbs) to illuminated electronic information displays (eg, LCD backlights and front lights) to medical devices and treatments. ...

AI Technical Summary

Problems solved by technology

[0006] Although new types of phosphors are being actively researched and developed, however, the construction of PLED-based light-emitting devices presents further challenges due to the nature of the available light-emitting materials.

These challenges include, for example, loss of light energy from photon conversion, self-heating of the phosphor from Stokes loss, dependence of photon conversion properties on operating temperature, chemical degradation of phosphor due to overheating or other damage Degradation due to permanent changes in physical composition, dependence of conversion properties on light intensity, propagation of light in undesired directions due to random emission of converted light emitted from phosphors, undesired chemical properties of phosphors and Controlled Deposition of Phosphors in Light-Emitting Devices

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