Patent number 8541795 is assigned to
The following quote was obtained by the news editors from the background information supplied by the inventors: "This invention relates to light emitting diode (LED) packages and more particularly to side-emitting LEDs.
"As illustrated in FIG. 1, many light sources, including many light emitting diode (LED) semiconductor die, produce light in a Lambertian radiation pattern with respect to an axis perpendicular to the base plane of the die. The majority of the light leaving the die is substantially forwardly directed, although much of it is at a wide angle. Many applications, however, require substantially all light to be directed at a wide angle, approaching or somewhat exceeding 90.degree., with little or no light at forward angles.
"In order to obtain a wide angle distribution of light from an LED package, a side-directing lens configured to redirect light may be added to the LED package. FIG. 2 illustrates a known LED package with such a lens. The LED package includes an LED chip, a lens with straight vertical sidewalls and a funnel-shaped top surface. There are two main paths in which light travels through the package. The first light path P1 is desirable. The light emitted from the chip travels to the top surface where total internal reflection (TIR) causes the light to exit through the sidewall at approximately 90.degree. to the longitudinal axis. The second light path P2 is light emitted from the chip towards the sidewall at an angle that causes TIR or reflection from the sidewall toward the top surface at an angle that allows the light to exit through the top surface. This path is not desirable and limits the efficiency of side extracted light.
"U.S. Pat. No. 6,607,286 discloses such another side-directing lens. The lens, which is shown in FIG. 3, includes a sawtooth, refractive portion and a top funnel portion. The sawtooth portion is intended to refract and bend light so that the light exits the lens close to 90.degree. with respect to the longitudinal axis of the LED. The sawtooth feature of this lens, however, makes the lens difficult to manufacture. For example, during an injection molding process, the undercuts of the sawtooth feature necessitate a side action injection mold."
In addition to the background information obtained for this patent, VerticalNews journalists also obtained the inventors' summary information for this patent: "Briefly, and in general terms, the invention is directed to light emitting diode (LED) packages and lenses for directing and emitting light at the side of an LED or other light source. In one aspect, the invention relates to an LED package that includes an LED structure that outputs light in a pattern about an axis and an optical coupling device with a central axis. The coupling device is positioned relative to the LED structure and accepts light from the LED. The coupling device includes a first dielectric interface surface that is substantially cylindrical with respect to the central axis, and a reflecting surface. The first dielectric interface surface accepts a first portion of light from the LED structure and directs it toward the reflecting surface. The reflecting surface accepts the light from the first dielectric interface surface and directs it toward the first dielectric interface surface in a direction substantially perpendicular to the central axis.
"In another aspect, the invention relates to a lens for use with a light emitting device that outputs light in a pattern about an axis. The lens includes a first dielectric interface surface that is substantially cylindrical with respect to a central axis and a reflecting surface that includes an inward-extending portion that extends into the cylinder defined by the first dielectric interface surface.
"In yet another aspect, the invention relates to a method of directing light from a light emitting device. The method includes generating light output from the light emitting device in a pattern about an axis and redirecting the light output using an optical coupling device having a central axis and positioned relative to the LED structure to accept light from the LED. The device includes a first dielectric interface surface that is substantially cylindrical with respect to the central axis, and a reflecting surface. Redirecting light includes accepting a first portion of light from the LED structure at the first dielectric interface surface and directing it toward the reflecting surface and accepting the light from the first dielectric interface surface at the reflecting surface and directing it toward the first dielectric interface surface in a direction substantially perpendicular to the central axis.
"These and other aspects and advantages of the invention will become apparent from the following detailed description and the accompanying drawings which illustrate by way of example the features of the invention."
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