US 6,155,699 A · Efficient phosphor-conversion led structure

Abstract

A light emitting device and a method of fabricating the device include a wavelength selective reflector that is formed between a light source and a layer of phosphorescent material. The light emitting device is a phosphor-conversion light emitting diode (LED) that outputs secondary light that is converted from primary light emitted from the light source. In the preferred embodiment, the light source is a Gallium Nitride (GaN) die and the wavelength selective reflector is a distributed Bragg reflector (DBR) mirror. The DBR mirror is comprised of multiple alternating layers of high and low refractive index materials. The high refractive index material may be Titanium Dioxide (TiO.sub.2) and the low refractive index material may be Silicon Dioxide (SiO.sub.2). An encapsulating layer over the GaN die provides a distance between the GaN die and the DBR mirror. Preferably, the encapsulating layer is a dome-shaped structure and the DBR mirror forms a dome-shaped shell over the encapsulating layer. In the most preferred embodiment, the dome-shaped configuration of the encapsulating layer and the DBR mirror is generally hemispheric. The dome-shaped configuration of the DBR mirror reduces the cone-angle average of the primary light from the light source, thereby improving the transmittance characteristic of the DBR mirror with respect to the primary light. Consequently, the amount of output light generated by the LED is significantly improved.

Claims20

Dependent claims

A light emitting device comprising:

a light generator responsive to an excitation signal for emitting first light in a wavelength range having a first peak wavelength;
a curved wavelength selective reflector that is spaced apart from the light generator by a predetermined distance, said wavelength selective reflector being substantially transmissive with respect to said first light that is propagating in a first direction away from said light generator, said wavelength selective reflector having a curved shape and being positioned to at least partially surround said light generator, said wavelength selective reflector being substantially reflective with respect to second light in a wavelength range having a second peak wavelength that is propagating in a second direction toward said light generator;
and
a wavelength converter fixed at a side of said wavelength selective reflector opposite to said light generator to receive said first light propagating from said wavelength selective reflector in said first direction, said wavelength converter being responsive to said first light to generate said second light having said second peak wavelength.

1 more element

A method of fabricating a light emitting device comprising steps of:

providing a light source that emits first light having a first peak wavelength;
depositing a transparent material over said light source such that said light source is at least partially encapsulated by said transparent material and such that said transparent material has a curved outer surface that is spaced apart from said light source, said transparent material providing a propagation medium for said first light having said first peak wavelength;
forming a wavelength selective reflector over said curved outer surface of said transparent material such that said wavelength selective reflector has a curved inner surface, said wavelength selective reflector configured to transmit said first light having said first peak wavelength and to reflect second light having a second peak wavelength;
and
depositing a layer of a phosphorescent material over said wavelength selective reflector, said phosphorescent material having a property of converting light energy having said first peak wavelength into light energy having said second peak wavelength.

2 more elements

A light emitting device comprising:

a light source responsive to an applied signal to emit first light having a first peak wavelength, said light source including a semiconductor chip and a plurality of layers, said light source having a generally planar outer surface;
a transparent structure positioned over said light source such that said light source is at least partially encapsulated by said transparent structure, said transparent structure having a curved outer surface that is spaced apart from said generally planar outer surface of said light source;
a wavelength selective reflector having a curved inner surface coupled to said curved outer surface of said transparent structure such that said transparent structure is located between said light source and said wavelength selective reflector, said wavelength selective reflector configured to transmit said first light having said first peak wavelength propagating in a first direction away from said light source and to reflect second light having a second peak wavelength propagating in a second direction toward said light source;
and
a layer of a phosphorescent material positioned over said wavelength selective reflector, said phosphorescent material having a property to absorb said first light having said first peak wavelength and generate said second light having said second peak wavelength.

2 more elements

Dependencies are inferred from the claim text.

Efficient phosphor-conversion led structure

Life of this patent

Efficient phosphor-conversion led structure

Life of this patent

Abstract

Claims20