Novel phosphor system for a white light emitting diode

Abstract

Novel phosphor systems for a white LED are disclosed. The phosphor systems are excited by a non-visible to near-UV radiation source having an excitation wavelength ranging from about 250 to 420 nm. The phosphor system may comprise one phosphor, two phosphors, and may include optionally a third and even a fourth phosphor. In one embodiment of the present invention, the phosphor is a two phosphor system having a blue phosphor and a yellow phosphor, wherein the long wavelength end of the blue phosphor is substantially the same wavelength as the short wavelength end of the yellow phosphor. Alternatively, there may be a wavelength gap between the yellow and blue phosphors. The yellow phosphor may be phosphate or silicate-based, and the blue phosphor may be silicate or aluminate-based. Single phosphor systems excited by non-visible radiation are also disclosed. In other embodiments of present invention, a single phosphor is used to produce white light illumination, the single phosphor having a broad emission spectrum with a peak intensity ranging from about 520 to 560 nm.

Description

technical field [0001] Embodiments of the present invention are generally directed to novel phosphors for use in white lighting systems such as white light emitting diodes (LEDs). Specifically, the white light LED of the present invention comprises: a radiation source emitting light in the non-visible to near ultraviolet (UV) to violet wavelength range; a first luminescent material comprising a blue phosphor; and a second luminescent material, It contains a yellow phosphor. Background technique [0002] Technology Development Status [0003] It has been proposed that white light illumination sources based entirely or in part on light emitting diodes will potentially replace conventional incandescent light bulbs. Such devices are often referred to as "white LEDs," although this may be a bit of a misnomer, as an LED is typically a system component that supplies energy to another component (a phosphor) that emits light of about one color ; light from several of these phosph...

AI Technical Summary

Problems solved by technology

[0021] LEDs that emit visible light, such as prior art LEDs with an InGaN active layer, have the disadvantage that during the deposition of the InGaN layer, the ratio of In to Ga varies resulting in a bandgap width that may deviate from the desired thickness of the active layer.

Also, phosphor manufacturing is not as prone to compositional errors as LED manufacturing

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