News Column

Patent Issued for Multi-Element LED Lamp Package

January 29, 2014



By a News Reporter-Staff News Editor at Electronics Newsweekly -- Cree, Inc. (Durham, NC) has been issued patent number 8629459, according to news reporting originating out of Alexandria, Virginia, by VerticalNews editors.

The patent's inventor is Hutchins, Edward Lloyd (Raleigh, NC).

This patent was filed on November 12, 2012 and was published online on January 14, 2014.

From the background information supplied by the inventors, news correspondents obtained the following quote: "In the field of exterior and interior illumination of motor vehicles, light-emitting diodes (LEDs) are being increasingly used instead of conventional incandescent bulbs, particularly for tail lights and brake lights, since LEDs have a longer service life, better efficiency in converting electrical energy into radiation energy in the visible spectral range, lower thermal emission characteristics, and reduced space requirements.

"The practical advantages of utilizing LED lamps instead of incandescent bulbs are many. The operational lifetime (in this case, defined as continuous illumination service) of a LED is on the order of ten years or over 50,000 hours, whereas incandescent bulbs often burn out after about 2,000 hours of service. Additionally, LED lamps are considerably more robust. When exposed to mechanical shocks or stresses, chemical stresses (e.g., such as may be caused by cleaning chemicals or road salt), or the presence of or temperature variations often encountered in an outdoor environment, LEDs are less likely to fail than incandescent lamps. This attribute is especially important when the lamp is utilized in motor vehicles wherein perishable filaments of incandescent lamps frequently break due to constant vibrational motion. Further, incandescent and fluorescent lamps are constructed with fragile glass exterior casings whose breakage compromises the operational utility of the lamp. In contrast, the solid state LED lamp has no filaments to break and is usually housed within a durable plastic casing, thereby exhibiting a high level of imperviousness to extreme outdoor environmental stresses. A further advantage of LEDs is that they have a more rapid turn-on time and generate less heat per lumen of light relative to conventional lighting products. The compact size and flexibility of form of LEDs offer still further advantages in relaxing space constraints and providing freedom to the designer to adopt new styling configurations, such as may be useful to create brand recognition.

"A LED is a solid-state device having a PN junction semiconductor diode that emits light when a current is applied. LEDs operate at relatively low current and voltage and emit substantially less heat per lumen than standard halogen or high intensity discharge (HID) lamps. The LED can be easily encapsulated in a resin material to protect the device and thus make it durable and long lasting. The use of semiconductor LEDs solves many problems associated with incandescent bulbs including, but not limited to, high entrapped heat, limited lamp longevity, frequent lamp replacement and higher current operation.

"Recently, higher brightness white light LED lamps have become increasingly affordable to manufacture and now present attractive substitutes for incandescent, halogen, and high intensity discharge (xenon discharge lamp) (HID) vehicle lamp sources. There are currently three methods for producing LEDs that emit white light. The first and second methods use a single blue, violet or UV LED die that emits a single wavelength of radiation, either with a phosphoric coating thereon or a phosphoric layer between the encapsulant and the lens, with the phosphor converting portions of the light into longer wavelengths that lead to the perception of white light. The third method uses independent red, blue, and green dies in the same package. When all three are powered, white light is perceived.

"Although more attractive as the illuminating source for the reasons enumerated above, LEDs have not become the favored light source for headlights and other lighting sources. For example, light distribution characteristics (particularly for low beam headlamps) of vehicle headlamps have been standardized, requiring a horizontal line that reduces glare on oncoming vehicles. Additionally, a minimum center luminous intensity of 8000 cd or more in the front view facilitates a driver's far distance visibility. These requirements are not readily satisfied using the single element reflector cup package known in the art.

"Headlamps including multiple LED packages have been proposed to achieve desired levels of total brightness and/or directionality. Each LED package includes a LED die plus a dedicated lead frame, reflector cup, encapsulant, and lens. The presence of multiple packages, particularly those redundant packages required to switch directionality, substantially increases the cost of the overall headlamp assembly and consumes significant volume, thus reducing packaging efficiency and reducing design options.

"Accordingly, there is a continuing need in the art for improved multi-LED light source assemblies that minimize lamp package quantities and footprint while enabling directional switching for vehicular and/or other lighting applications."

Supplementing the background information on this patent, VerticalNews reporters also obtained the inventor's summary information for this patent: "The present invention relates in one aspect to a multi-LED light source assembly employing a plurality of LED elements in a single package, with each LED element capable of being switched independently of one another. At least two LEDs may be arranged in the same package assembly to focus light in the same or different directions without changing the position of the assembly.

"In another aspect, the invention relates to a light emitting diode (LED) lamp, comprising: a reflector cup having a vertex, a focal point, a principal axis, an inside surface, and an open face; a first LED die disposed within the reflector cup at a first position at the focal point of the reflector; and at least one additional LED die disposed within the reflector cup at position different from the first position. The position different from the first position may be other than along the principal axis, or may be along the principal axis but not coincident with the focal point.

"In another aspect, the invention relates to a light emitting diode (LED) package comprising: a first LED sub-assembly comprising a first LED die, a first reflector having a first principal axis, and a first lens; a second LED sub-assembly comprising a second LED die, a second reflector having a second principal axis, and a second lens; and a common lead frame, wherein the first LED sub-assembly and the second LED sub-assembly are mounted to the common lead frame, the first LED sub-assembly is adapted to emit a first beam in a first direction, and the second LED sub-assembly is adapted to emit a second beam in a second direction that is different from the first direction. In one embodiment, each of the first LED sub-assembly and the second LED sub-assembly is independently controlled.

"In another aspect, the invention relates to a method of adjusting any of the intensity, color, and direction of light originating from a light emitting diode (LED) lamp, the method including the steps of: providing multiple LED die within a reflector cup with a first LED die disposed at the focal point and at least one additional die at a location other than along the principal axis of the reflector cup; and independently operating the first LED die and the at least one additional LED die.

"In another aspect, the invention relates to a method of adjusting the color of light originating from a light emitting diode (LED) lamp, the method comprising the steps of:

"providing a reflector cup having a vertex, a focal point, a principal axis, an inside surface, and an open face; providing a first RGB LED within the reflector cup, the first RGB LED having a first red die, a first green die, and a first blue die; providing a second RGB LED within the reflector cup, the second RGB LED having a second red die, a second green die, and a second blue die; and independently operating at least one of: any of the red dies, the blue dies, and the green dies.

"In another aspect, any of the foregoing aspects may be combined for additional advantage.

"Other aspects, features and embodiments of the invention will be more fully apparent from the ensuing description and claims."

For the URL and additional information on this patent, see: Hutchins, Edward Lloyd. Multi-Element LED Lamp Package. U.S. Patent Number 8629459, filed November 12, 2012, and published online on January 14, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=50&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=2465&f=G&l=50&co1=AND&d=PTXT&s1=20140114.PD.&OS=ISD/20140114&RS=ISD/20140114

Keywords for this news article include: Cree Inc., Electronics, Semiconductor, Light-emitting Diode.

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Source: Electronics Newsweekly


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