News Column

Patent Issued for LED Structure to Increase Brightness

August 20, 2014

By a News Reporter-Staff News Editor at Electronics Newsweekly -- A patent by the inventor Shum, Frank (Sunnyvale, CA), filed on September 28, 2010, was published online on August 5, 2014, according to news reporting originating from Alexandria, Virginia, by VerticalNews correspondents.

Patent number 8796708 is assigned to Kabushiki Kaisha Toshiba (Tokyo, JP).

The following quote was obtained by the news editors from the background information supplied by the inventors: "The present disclosure relates to a light emitting diode (LED), and more particularly, to an LED with a high brightness output.

"Light emitting diodes (LED) have been developed for many years and have been widely used in various technology areas. Because LEDs have better electrical power to light conversion efficiency than the conventional incandescent lighting and longer lifetimes than both the conventional incandescent and fluorescent light sources, they have been good candidates for replacing these conventional light sources.

"The brightness or luminance of an LED is an important quality that specifies how it will illuminate a particular location. For applications such as rear projection TVs, presentation projectors, and automobile headlights, among others, the brightness is a particularly important factor.

"The light brightness or luminance (L) of a light source is proportional to the optical power (.phi.) of the light source, as shown below: L=.phi./(A.OMEGA.), where A is an area of the source and .OMEGA. is a solid angle of light emission.

"Typically, the area (A) and the solid angle .OMEGA. are constant. Therefore, traditionally, the current supplied to the LED must be increased to increase the luminance. Increasing the current, i.e., increasing the current density, however, also decreases the reliability of the LED. Even if the reliability of the LED is not a concern, once the current density is above a certain limit, the optical power will 'roll over,' resulting in a decrease in brightness. Increasing the current density also increases the power density or the heat generated per unit area, which is not a desirable result.

"Accordingly, there is a need in the art to achieve an increase in the brightness of the LEDs without increasing current or power density."

In addition to the background information obtained for this patent, VerticalNews journalists also obtained the inventor's summary information for this patent: "In one aspect of the disclosure, a light emitting semiconductor device includes an LED having an emission aperture located on a surface of the LED. The emission aperture has a size that is smaller than the surface area of the LED where the emission aperture is formed.

"In another aspect of the disclosure, a light emitting semiconductor device includes an LED having two side walls, a bottom surface, a top surface and an emission aperture located on the top surface of the LED, and a reflector formed on the bottom surface and portions of the top surface of the LED. The area on the top surface uncovered by the reflector forms the emission aperture and is smaller than an area of the top surface of an LED.

"In still another aspect of the disclosure, a light emitting semiconductor device includes an LED having an emission aperture located on a surface of the LED. An area of the emission aperture is smaller than a surface area of the LED, and the area of the emission aperture is roughened.

"It is understood that other aspects of the present invention will become readily apparent to those skilled in the art from the following detailed description, which shows and describes exemplary aspects of the invention by way of illustration. As will be realized, the invention includes other and different aspects and its several details are capable of modification in various other respects, all without departing from the spirit and scope of the present invention. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not as restrictive."

URL and more information on this patent, see: Shum, Frank. LED Structure to Increase Brightness. U.S. Patent Number 8796708, filed September 28, 2010, and published online on August 5, 2014. Patent URL:

Keywords for this news article include: Electronics, Semiconductor, Kabushiki Kaisha Toshiba.

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Source: Electronics Newsweekly

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