Patent number 8604684 is assigned to
The following quote was obtained by the news editors from the background information supplied by the inventors: "Light emitting diode (LED) lighting systems are becoming more prevalent as replacements for existing lighting systems. LEDs are an example of solid state lighting (SSL) and have advantages over traditional lighting solutions such as incandescent and fluorescent lighting because they use less energy, are more durable, operate longer, can be combined in red-blue-green arrays that can be controlled to deliver virtually any color light, and generally contain no lead or mercury. In many applications, one or more LED dies (or chips) are mounted within an LED package or on an LED module, which may make up part of a lighting unit, lamp, 'light bulb' or more simply a 'bulb,' which includes one or more power supplies to power the LEDs. An LED bulb may be made with a form factor that allows it to replace a standard threaded incandescent bulb, or any of various types of fluorescent lamps. LEDs can also be used in place of florescent lights as backlights for displays.
"Translucent or transparent rigid materials may be used with LED lighting to provide diffusion, color mixing, to otherwise direct the light, to serve as an enclosure to protect the LEDs and/or other electronic components, or to provide a support for wavelength conversion material sometimes used to achieve accurate color. Wavelength conversion materials may produce white light when struck by light of a specified color, or may produce an additional color of light that mixes with other colors of light to produce white light, or another specific desired color of light. As an example, phosphor particles can be used as a wavelength conversion material. Phosphor absorbs light at one wavelength and reemits light at a different wavelength. Typically, phosphor particles are randomly distributed within a matrix of encapsulant material. The term phosphor can refer to materials that are sometimes also referred to as fluorescent and/or phosphorescent.
"To be used as part of an LED lamp or LED lighting system, phosphor is often applied to or included in a transparent or translucent carrier or substrate. Thus, materials such as acrylic, glass or polycarbonate are often used in LED lighting systems as optical elements, both with and without phosphors. In lighting systems where the LEDs emit ultraviolet (UV) light, consumable UV-stabilizing additives are used in acrylic or polycarbonate substrates so that the material maintains its clarity and strength over time despite the UV exposure. Even in LED systems that generate small amounts of actual UV light, near UV light that may be emitted can be almost as damaging to polymers as UV light. For example, GaN LEDs emit vanishingly small amounts of actual UV light, but large amounts of deep blue, near UV light that can have the same effects as UV light on acrylic or polycarbonate substrates."
In addition to the background information obtained for this patent, VerticalNews journalists also obtained the inventor's summary information for this patent: "Embodiments of the invention include an optical element made from an inherently UV stable polyester, so that consumable UV-stabilizing additives are not needed. Thus, the rigid form of the optical element of embodiments of the invention can maintain its transparency over longer periods of time in the face of high levels of UV or near UV light as compared to materials requiring additives typically used to stabilize polymers against UV exposure. Such additives are consumable and thus disappear from the material over time. In addition, the substrate material in at least some embodiments of the invention exhibits good mechanical temperature stability, high transmissivity, good flame barrier characteristics, and is capable of achieving varied geometries with tight mechanical tolerances.
"In some embodiments, an optical element for an LED lighting system includes a form made from inherently UV stable polyester. The form is shaped to receive at least some light from an LED or LEDs. The form can serve as a carrier or substrate for an appropriate phosphor to be used for remote wavelength conversion. The phosphor is distributed to be coincident with the form, possibly in an applied encapsulant or in the material itself, to provide the wavelength conversion.
"In some embodiments, the inherently UV stable polyester further comprises aromatic polyester. In some embodiments, the aromatic polyester is polyarylate. The phosphor can be included by applying an encapsulant containing the phosphor the surface of the form. Alternatively, the phosphor can be disbursed within the form. The substrate carrier form can also in some embodiments be molded to include a cavity, and the cavity can be filled with an encapsulant containing the phosphor.
"An optical element according to example embodiments of the invention can be used in an LED lamp. Such an LED lamp can be assembled from the form with or without the phosphor added as previously described. A power supply is provided within the lamp housing and the power supply is electrically connected to an LED assembly including one or more LEDs. The optical element is attached to the housing as appropriate so that the phosphor receives light from the LED assembly and provides remote wavelength conversion.
"In some embodiments, the form is dome shaped. The form may be the only optical element of an LED lamp. Alternatively, an LED lamp may be constructed that uses one optical element primarily for remote wavelength conversion, while using a second optical element for other purposes such as diffusion, color mixing, or the like. In the latter case, either or both optical elements may be a rigid form made of the UV stable polyester described herein."
URL and more information on this patent, see: Pickard,
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