News Column

Researchers Submit Patent Application, "Multi-Element Led Lamp", for Approval

May 7, 2014



By a News Reporter-Staff News Editor at Electronics Newsweekly -- From Washington, D.C., VerticalNews journalists report that a patent application by the inventor Hutchins, Edward Lloyd (Raleigh, NC), filed on December 20, 2013, was made available online on April 24, 2014.

The patent's assignee is Cree, Inc.

News editors obtained the following quote from the background information supplied by the inventors: "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."

As a supplement to the background information on this patent application, VerticalNews correspondents also obtained the inventor's summary information for this patent application: "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.

BRIEF DESCRIPTION OF THE DRAWINGS

"FIG. 1 is a schematic of a conventional single element reflector cup lamp package known in the art.

"FIG. 2 is a side cross-sectional schematic of a first surface mount LED package according to the present invention, the package including multiple elements disposed under a symmetric lens.

"FIG. 3 is a side cross-sectional schematic of a second surface mount LED package according to the present invention, the package including multiple elements disposed under an asymmetric lens.

"FIG. 4 is a side cross-sectional schematic of a third surface mount LED package according to the present invention, the package including two lamp subassemblies mounted to a common lead frame, the subassemblies having non-parallel principal axes with symmetric lenses, symmetric reflectors, and die placed along the principal axis of each subassembly.

"FIG. 5 is a two-dimensional illustration of beam paths generated by a conventional reflector known the in the art, the reflector including one LED die, wherein substantially parallel light beams are reflected parallel to the principal axis of the reflector.

"FIG. 6 is a two-dimensional illustration of beam paths generated by a lamp assembly according to the present invention including a reflector and at least two LED dies, wherein light is reflected in at least two different directions.

"FIG. 7 is a cross-sectional schematic illustration of an alternative reflector having horizontal facets for use with a lamp assembly according to the present invention.

"FIG. 8 is a cross-sectional schematic illustration of another alternative reflector having vertical facets for use with a lamp assembly according to the present invention.

"FIG. 9 is a schematic illustration of another alternative reflector having two partial paraboloids (the upper partial paraboloid having a smaller focal length than the lower partial paraboloid) with a common apex for use with a lamp assembly according to the present invention.

"FIG. 10 is a schematic illustration of another alternative reflector having two partial paraboloids (the upper partial paraboloid having a larger focal length than the lower partial paraboloid) with having a common apex for use with a lamp assembly according to the present invention.

"FIG. 11 is a schematic depicting the relevant axes of a reflector relative to the angles of reflection.

"FIG. 12A is a side cross-sectional schematic of a fourth surface mount LED package according to the present invention, the package including two lamp subassemblies mounted to a common lead frame and each having a single die, each subassembly having symmetric lenses and symmetric reflectors, with the die of the first (left) subassembly being disposed coincident with the principal axis, and with the die of the second (right) subassembly being disposed non-coincident with the principal axis.

"FIG. 12B is a side cross-sectional schematic of a fifth surface mount LED package according to the present invention, the package including multiple die, with one die disposed coincident with principal axis of the subassembly and the other die disposed non-coincident with the principal axis.

"FIG. 12C is a side cross-sectional schematic of a sixth surface mount LED package according to the present invention, the package including two lamp subassemblies mounted to a common lead frame and each having a single die, each subassembly having a symmetric lens and a die disposed along the principal axis, with the first (left) subassembly having a symmetric reflector and the second (right) subassembly having an asymmetric reflector.

"FIG. 12D is a side cross-sectional schematic of a seventh surface mount LED package according to the present invention, the package including multiple die, a symmetric lens, and an asymmetric reflector, with both die being non-coincident with the principal axis but symmetrically arranged equidistantly from the principal axis.

"FIG. 12E is a side cross-sectional schematic of a eighth surface mount LED package according to the present invention, the package including two lamp subassemblies mounted to a common lead frame and each having a single die and a symmetric lens, with the first (left) subassembly having a symmetric reflector and a die disposed coincident with the principal axis, and with the second (right) subassembly having an asymmetric reflector and a die disposed non-coincident with the principal axis.

"FIG. 12F is a side cross-sectional schematic of a ninth surface mount LED package according to the present invention, the package including multiple die, a symmetric lens, and an asymmetric reflector, with one die disposed coincident with the principal axis and the other die disposed non-coincident with the principal axis.

"FIG. 12G is a side cross-sectional schematic of a tenth surface mount LED package according to the present invention, the package including two lamp subassemblies mounted to a common lead frame and each having a symmetric reflector and a die disposed coincident with the principal axis, the first (left) subassembly having a symmetric lens and the second (right) subassembly having an asymmetric lens.

"FIG. 12H is a side cross-sectional schematic of an eleventh surface mount LED package according to the present invention, the package including multiple die, a symmetric reflector, and an asymmetric lens, with both die being non-coincident with the principal axis but symmetrically arranged equidistantly from the principal axis.

"FIG. 12I is a side cross-sectional schematic of a twelfth surface mount LED package according to the present invention, the package including two lamp subassemblies mounted to a common lead frame and each having a symmetric reflector, the first (left) subassembly having a symmetric lens and a die disposed coincident with the principal axis, and the second (right) subassembly having an asymmetric lens and a die disposed non-coincident with the principal axis.

"FIG. 12J is a side cross-sectional schematic of a thirteenth surface mount LED package according to the present invention, the package including multiple die, a symmetric reflector, and an asymmetric lens, with one die disposed coincident with the principal axis and the other die disposed non-coincident with the principal axis.

"FIG. 12K is a side cross-sectional schematic of a fourteenth surface mount LED package according to the present invention, the package including two lamp subassemblies mounted to a common lead frame, each subassembly having a single die disposed coincident with the principal axis, the first (left) subassembly having a symmetric lens and symmetric reflector, and the second (right) subassembly having an asymmetric lens and an asymmetric reflector.

"FIG. 12L is a side cross-sectional schematic of a fifteenth surface mount LED package according to the present invention, the package including multiple die, an asymmetric reflector, and an asymmetric lens, with both die being disposed non-coincident with the principal axis but symmetrically arranged equidistantly from the principal axis.

"FIG. 12M is a side cross-sectional schematic of a sixteenth surface mount LED package according to the present invention, the package including two lamp subassemblies mounted to a common lead frame, with the first (left) subassembly having a symmetric lens, symmetric reflector, and a die disposed coincident with the principal axis, and with the second (right) subassembly having an asymmetric lens, an asymmetric reflector, and a die disposed non-coincident with the principal axis.

"FIG. 12N is a side cross-sectional schematic of a seventeenth surface mount LED package according to the present invention, the package including multiple die, an asymmetric reflector, and an asymmetric lens, with one die disposed coincident with the principal axis and the other die disposed non-coincident with the principal axis."

For additional information on this patent application, see: Hutchins, Edward Lloyd. Multi-Element Led Lamp. Filed December 20, 2013 and posted April 24, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=4414&p=89&f=G&l=50&d=PG01&S1=20140417.PD.&OS=PD/20140417&RS=PD/20140417

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

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Source: Electronics Newsweekly


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