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`US 8,449,150 B2
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`a2) United States Patent
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`May28, 2013
`(45) Date of Patent:
`Allen et al.
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`US008449150B2
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`(54) TIR LENS FOR LIGHT EMITTING DIODES
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`Inventors: Steven C. Allen, Beverly, MA (US);
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`Hong Luo, Danvers, MA (US); Angela
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`Hohl-AbiChedid, Beverly, MA (US)
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`(75)
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`(73) Assignee: OSRAM SYLVANIAInc., Danvers
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`MA(US)
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`Subject to any disclaimer, the term ofthis
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`patent is extended or adjusted under 35
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`U.S.C. 154(b) by 500 days.
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`ne
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`(*) Notice:
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`(21) Appl. No.: 12/364,934
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`Feb. 3, 2009
`Filed:
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`(22)
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`Prior Publication Data
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`US 2010/0195335 Al
`Aug. 5, 2010
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`Int. Cl.
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`(2006.01)
`F21V 5/04
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`(2006.01)
`F21V 3/02
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`(52) U.S.CL.
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`USPC vececeeeeeee 362/311.06; 362/311.02; 362/308,
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`362/327; 362/335; 362/520; 313/512
`(58) Field of Classification Search
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`USPC viececccceserees 362/520, 545, 244, 245, 249.02,
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`362/308, 311.02, 311.06, 311.15, 311.11,
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`362/327, 335, 339, 340; 313/512
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`See application file for complete search history.
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`References Cited
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`U.S. PATENT DOCUMENTS
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`2,215,900 A *
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`5/1949 Rosinetal. occ 362/327
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`6/1996 Hubble,ITI et al.
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`6,896,381 B2*
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`7,021,797 B2
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`7,111,964 B2*
`9/2006 Suehiro et al. oo... 362/328
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`7,270,454 B2*
`9/2007 AMANO ceccccssssssseeseeeeeen 362/522
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`7,329,029 B2
`2/2008 Chavesetal.
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`7,473,013 B2*
`1/2009 Shimada oo... 362/327
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`7,847,480 B2* 12/2010 Yonedaetal. wo... 313/512
`2005/0201118 Al
`9/2005 Godo
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`2008/0054281 Al
`3/2008 Narendran etal.
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`2008/0062703 Al
`3/2008 Cao
`OTHER PUBLICATIONS
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`European Search Report and Annex for corresponding European
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`Patent Application 10152400.7, mailed Jun. 28, 2010, Applicant:
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`Osram SylvaniaInc.
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`* cited by examiner
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`Primary Examiner — Ismael Negron
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`(74) Attorney, Agent, or Firm — Shaun P. Montana
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`57
`ABSTRACT
`6)
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`An optical element is disclosed. The optical element includes
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`a single,
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`batwing shaped cross-section, extending angularly away
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`from a longitudinal axis. The lens also includes a variety of
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`curved, straight, specular and optionally diffuse portions on
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`its longitudinal and transverse faces, all of which cause a
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`variety of internal and external reflections, refractions, and
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`optionally scattering.
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`7 Claims, 8 Drawing Sheets
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`SAMSUNG EXHIBIT 1038
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`US 8,449,150 B2
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`90°
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`Fig. 1
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`PRIOR ART
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`Fig. 3
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`PRIOR ART
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`270°
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`US 8,449,150 B2
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`1
`TIR LENS FOR LIGHT EMITTING DIODES
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`CROSS-REFERENCE TO RELATED
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`APPLICATIONS
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`Not Applicable
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`STATEMENT REGARDING FEDERALLY
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`SPONSORED RESEARCH OR DEVELOPMENT
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`Not Applicable
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`BACKGROUNDOF THE INVENTION
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`batteries, or may connect electrically to an external power
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`supply. The printed circuit board 6 may include one or more
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`threaded holes, through-holes, and/or locating features. The
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`printed circuit board 6 may have any suitable shape, such as
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`round, square, rectangular, hexagonal, and so forth.
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`The support platform 7 is optional, and may include the
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`mechanicalandelectrical connections required to elevate the
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`LEDs a suitable distance above the actual printed circuit
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`board plane.
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`The emission surface 8 is the physical location ofthe light
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`emitting diode plane. It is assumedthat all the LEDs in the
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`LED module 3 have their respective outputs emit from the
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`same emission plane8, although this need notbe the case. In
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`this application, the emission plane 8 is drawn as the topmost
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`surface of three horizontally-oriented rectangles, which rep-
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`resent three adjacent LED facets, chips or dies. The LEDs
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`maybe arranged in an array, such as a 1 by 2, a 1 by 3, a 2 by
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`2, a 2 by 3, a3 by 3, a single LED, or any other suitable
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`number of LED facets. The LED array may be arranged in a
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`rectangular pattern, or any other suitable pattern.
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`A lens 9 encapsulates the LED array. The lens may encap-
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`sulate all the LEDsin the emission plane, as drawn in FIG.3,
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`or may encapsulate fewer than all the LEDs in the emission
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`plane. Alternatively, the lens 9 may be a series of lenses, each
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`encapsulating its own LED in the emission plane.
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`In general, it is intended that many styles of commercially
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`available packaged LEDs may be used as the LED module 3.
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`For instance, one possible candidate for the LED module3 is
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`commercially available from Osram, and sold under the
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`OSTAR name. Other products from Osram and from other
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`manufacturers are available as well, and may equally well be
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`Light emitted perpendicular to the LED array 3 is denoted
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`as having an angle of 0 degrees, with angles of 90 degrees and
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`270 being parallel to the emission plane 8. A plot 4 of the
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`relative power output from this LED array 3 shows a much
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`more narrow distribution than the plot of FIG. 1. Here, the
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`LEDarray 3 hasits peak output at 0 degrees, with a falloff to
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`essentially zero at 90 and 270 degrees.
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`In general, light emitted from a typical LED module 3 is
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`found to have a generally Lambertian distribution in power
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`per angle. A Lambertian distribution has a peak thatis ori-
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`ented normal to the emitting surface (often denoted as 0
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`degrees), with an angular falloff of cos 0, where 8 is with
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`respect to the surface normal. This Lambertian distribution
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`maybe represented numerically bya full-width-at-half-maxi-
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`mum (FWHM)in angle, given by 2 cos’ (0.5), or 120
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`degrees. Actual LED modules 3 may have angular distribu-
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`tionsthatvary slightly from the FWHMvalueof 120 degrees,
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`such asin the range of about 90 degrees to about 130 degrees,
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`but the 120 degree value is considered to be a generally good
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`approximation,and is used accordingly throughoutthis docu-
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`One knownapproachfor having an angularly broad output
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`from the LEDsis to distribute multiple LED sources over one
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`or more non-planar surfaces, such as the outside of a sphere or
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`cylinder. There is a line of commercially available products
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`that use in their light engines outward-facing LED chips
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`mounted around the circumference of a cylinder, which
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`results in a beam width of about 275 degrees. These light
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`engines are available in LED products from CAO Group in
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`West Jordan, Utah.
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`There area several drawbacks to mounting the LEDs on a
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`non-planar surface. First, such a mounting arrangementis
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`complicated, time- and labor-intensive, and expensive. Sec-
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`ond, such a mounting arrangement cannotuse standard, off-
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`1. Field of the Invention
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`The present invention is directed to an optical element for
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`receiving relatively narrow light from a planarlight-emitting
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`diode (LED) source, and for redistributing the light into a
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`relatively wide range of output angles that span a full 360
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`2. Description of the Related Art
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`Light emitting diodes (LEDs) are rapidly finding accep-
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`tance in many lighting applications. Compared with incan-
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`descent light bulbs, LEDs are more efficient, have longer
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`lifetimes, and may be packaged in a wide variety of suitably
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`The cone of light emerging from a typical LED is rather
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`narrow. While this may be a desirable characteristic for some
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`applications, such as spotlights, there are other applications
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`where it may be desirable to have a wider angular output. In
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`particular, there are “retrofit” applications that replace incan-
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`descent bulbs with LEDs. These “retrofit” applications would
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`use LEDs or LED arraysas their light sources, but would
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`conditionthe light output to mimicthat of a typical incandes-
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`cent bulb. In this manner, a user can keep an existing lighting
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`fixture, and can realize some of the benefits of using LEDs.
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`It is instructive to examinein detail the angular light output
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`from typical incandescent bulbs and typical LEDs.
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`FIG.1 is schematic drawingofa typical incandescent bulb
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`1, and FIG.2 is a plot 2 of the bulb’s relative power output as
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`a function of emergent angle. Ifthe angular direction opposite
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`the screw threads of the bulb is denoted as 0 degrees, then the
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`relative powerprofile may look essentially constant over the
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`range of 0 degrees, tabout 150 degrees. For angles outside
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`this range, there is somefalloff of the relative power, caused
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`by a shadowing from the threaded stem ofthe bulb. The power
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`profile reaches its minimum value around 180 degrees, or
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`parallel to the threaded stem. The minimum value may be
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`zero, or may befinite but non-zero.
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`One possible measure of the width of such a powerdistri-
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`bution is the full-width-at-half-maximum (FWHM); other
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`measures are possible, as well. A typical incandescent bulb
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`may have an emission pattern with a FWHM of about 300
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`degrees. Using the angles as drawn in FIG. 1, aFWHM of300
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`degrees meansthat the angular light output falls to half ofits
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`maximum value at angles of 210 degrees and 150 degrees.
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`Note that for this general discussion, we ignore any differ-
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`ences in angular output between angles measuredin the page
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`of FIG. 1 and out of the page of FIG.1.
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`In contrast with the relatively wide angulardistribution of
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`FIGS. 1 and 2, FIGS. 3 and 4 shows comparable angular
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`poweroutputs from a typical LED module3.
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`The LED module 3 includes a printed circuit board 6, a
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`support platform 7, an emission surface 8, and a lens 9.
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`The printed circuit board 6 mechanically supports the
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`LEDsand supplies electrical power to the LEDs. The printed
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`circuit board 6 may include its own power supply, such as
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`Page 10 of 16
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`US 8,449,150 B2
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`extending toward the longitudinal axis of the lens, the curvi-
`the-shelf LED packages. Both of these drawbacks make the
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`linear portion including a convex portion and a concave por-
`CAO Group approachless than optimal.
`tion.
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`Another known approach is disclosed in U.S. Pat. No.
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`A further embodimentis a wide-angle light emission sys-
`7,021,797, titled “Optical device for repositioning andredis-
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`tem, comprising: a generally planar light emitting diode mod-
`tributing and LED’s light”, issued on Apr. 4, 2006 to Juan C.
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`ule for emitting light in an angular distribution centered
`Miiianoet al. Mijiano discloses an optical device forspatially
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`around a longitudinal axis, the longitudinal axis being sub-
`displacing the output of a light-emitting diode (LED) and
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`stantially perpendicular to the light emitting diode module;
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`coupling the output to a predominantly spherical emission
`and a lens for receiving light from the planar light emitting
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`pattern produced at a useful height above the LED. The device
`diode module The lens extends longitudinally away from the
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`ofMifiano is madeof a transparentdielectric material, suchas
`light emitting diode module andis disposed on only oneside
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`an injection-molded plastic. It comprises a lower transfer
`ofthe light emitting diode module plane. The lens has an inner
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`section that receives the LED’s light from below and an upper
`longitudinal thickness proximate the longitudinal axis, an
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`ejector section that receives the transferred light and spreads
`outer longitudinalthickness proximate an outerradial edge of
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`it spherically. One or more LEDsare optically coupledto the
`the lens, and an intermediate longitudinal thickness between
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`bottom ofthe transfer section, which operates bytotal internal
`the longitudinal axis and the radial edge of the lens, the
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`reflection upontheir entire hemispherical emission.
`intermediate longitudinal thickness being greater than both
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`A potential drawback to the device of Mifianois thatit is
`the inner longitudinal thickness and the outer longitudinal
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`quite large, and has a significant longitudinal extent beyond
`thickness. The lens comprises a material having a refractive
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`the LED chips. One of the applications disclosed by Miiiano
`index greater than one, the material having an exterior sur-
`20
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`is use of the device inaflashlight, where LEDs would radiate
`face, a radial cross-section of the exterior surface having a
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`into the device, then the light output ofthe device would strike
`distal side facing away from the light emitting diode module,
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`a parabolic mirror and leave the flashlight as a collimated
`the distal side including both a distal convex portion and a
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`beam. While such a device may be suitable for a flashlight,
`distal concave portion, and having a proximal side facing
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`whichalreadyhas a natural longitudinal shape, such a device
`toward the light emitting diode module, the proximal side
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`may not be suitable for an incandescent-bulb replacement,
`including: a proximal concave portion at the center of the
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`which mayfit in a much smaller spatial envelope.
`proximalside for receiving light from thelight-emitting diode
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`Accordingly, there exists a need for an optical element that
`module; and a total internal reflection portion circumferen-
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`can use a planar LED module asalight source, can direct the
`tially surrounding the proximal concave portion for totally
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`relatively narrow light from the LED module intoarelatively
`internally reflecting light that enters the lens through the
`30
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`wide beam,andcanfit in the relatively small spatial envelope
`concave portion and directly strikes the total internal reflec-
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`required to “retrofit” existing incandescentfixtures.
`tion portion.
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`25
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`BRIEF SUMMARY OF THE INVENTION
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`An embodimentis a device for angularly broadening light
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`emitted from a light-emitting diode module, comprising: a
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`lens having a symmetry about a longitudinal axis; the lens
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`comprising a transparent material bounded by an exterior
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`surface; the exterior surface comprising a batwing structure
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`that converts a Lambertian input distribution of light rays
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`emitted from the light-emitting diode module into a generally
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`uniform output distribution of light rays emerging from the
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`lens; the batwing structure comprising a proximal portion
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`facing the light-emitting diode module, the proximal portion
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`comprising: a concave portion at the center of the proximal
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`portion, and a total internal reflection portion circumferen-
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`tially surrounding the concave portion. Any light ray that
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`enters the lens from the light-emitting diode module does so
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`through the concaveportion. Any light ray that enters the lens
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`through the concave portion and directly strikes the total
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`internalreflection portion doesso at an incident angle greater
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`thana critical angle for the lens.
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`Another embodimentis a device for broadening an angular
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`light output of a light-emitting diode module, comprising: a
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`lens for receiving light from the light-emitting diode module
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`and emitting light into a plurality of exiting angles, the lens
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`having a characteristic emission pattern wider than that of the
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`light emitting diode module, the lens comprising a material
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`having a refractive index greater than one,
`the material
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`bounded byan exterior surface, a radial cross-section of the
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`exterior surface comprising: a first linear section extending
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`away from a longitudinal axis of the lens; a second substan-
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`tially linear section adjacent to the first linear section and
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`substantially parallel to the longitudinal axis of the lens; a
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`third linear section adjacent to the second linear section and
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`extending toward the longitudinal axis of the lens; and a
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`curvilinear portion adjacent to the third linear section and
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`Page 11 of 16
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`BRIEF DESCRIPTION OF THE SEVERAL
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`VIEWS OF THE DRAWINGS
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`FIG. 1 is schematic drawing of a typical incandescent bulb.
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`FIG. 2 is a polarplot of relative power output as a function
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`of emergent angle, for the bulb of FIG. 1.
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`FIG. 3 is schematic drawing of a typical light emitting
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`diode (LED) module.
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`FIG.4 is a polarplot of relative power output as a function
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`of emergent angle, for the LED module of FIG.3.
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`FIG. 5 is a schematic drawing of an optical element that
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`receives the light emitted by an LED module and directs it
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`into a full 360 degrees
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`FIG.61s a plot of an idealized angular power outputof the
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`optical element of FIG.5.
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`FIG.7 is a cross-sectional schematic drawing of a batwing
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`lens showing light input and output.
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`FIG. 8 is a cross-sectional schematic drawing of the
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`batwinglens of FIG.7.
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`FIG.9 is a polar plot of the simulated emitted power per
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`angle as a function of angle, for the lens of FIGS. 7 and8.
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`FIG. 10 is a cross-sectional schematic drawing ofa pris-
`matic element.
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`FIG.11 is a cross-sectional schematic drawing ofa shell
`reflector.
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`FIG. 12 is a cross-sectional schematic drawing of a plate
`redirector.
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`FIG. 13 is a schematic drawing of the lens and control
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`electronics, overlaid with a dimensioned drawing ofan exem-
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`plary volume envelope for an incandescentfixture.
`DETAILED DESCRIPTION OF THE INVENTION
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`An optical element is disclosed, for receiving relatively
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`narrow light from a planarlight-emitting diode (LED) source,
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`Page 11 of 16
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`5
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`and for redistributingthe light into a relatively wide range of
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`output angles that span a full 360 degrees. The element may
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`be used to retrofit existing fixtures that were originally
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`designed for incandescent bulbs with LED-based light
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`sources that have similar emission profiles. The elementis
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`small enoughso that it may be packaged along with an LED
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`module andits control electronics in the volume envelope of
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`an incandescentlight bulb. An exemplary elementis a single,
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`transparent, rotationally-symmetric lens that has a batwing
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`shape in cross-section, extending angularly away from a lon-
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`gitudinal axis. The lens also includes a variety of curved,
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`straight, specular and, optionally, diffuse portions on its lon-
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`gitudinal andtransverse faces, all of which cause a variety of
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`internal and externalreflections, refractions, and, optionally,
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`scattering. As such, manyofthe specific lens features cannot
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`be directly linked to specific optical effects at a particular
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`angle; rather, the features all interact with each other to pro-
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`duce the wide-angle light output.
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`The preceding paragraph is merely a summary, and should
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`not be construed as limiting in any way. A more complete
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`description is providedin the figures andthetext that follows.
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`Asstated above, it would be desirable to have an optical
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`elementthat widensthe relatively narrow angular output 4 of
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`a planar LED module 3 to resemblethe relatively wide angu-
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`lar output 2 of an incandescent bulb 1. FIG. 5 is a schematic
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`drawing of such an optical element 10, which receives the
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`light emitted by an LED module 3 anddirectsit into a full 360
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`degrees. FIG.6 is a plot of an idealized angular power output
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`of the optical element 10, which is essentially uniform over a
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`full 360 degrees. This uniform output 5 is a design goal; in
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`practice, there may be some non-uniformities to the angular
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`output, which would show up as jaggedness in someorall
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`portionsof the circle in FIG.6.
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`There are many possibilities for the optical element 10.
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`Four such possibilities are described in detail below, and are
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`denoted with element numbers 10A, 10B, 100 and 10D. All
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`four are functionally equivalent to the “black box”optical
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`element 10 shownin FIG.5; they all receive relatively narrow
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`light from an LED module 3 andredirect it into a relatively
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`wide angular range that includesa full 360 degrees, as shown
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`in the graph ofthe uniform output 5 of FIG. 6. Each ofthe four
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`designs is described sequentially below.
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`Thefirst design for the optical element 10 is shown in the
`45
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`cross-sectional schematic drawing ofFIG. 7. A lens 10A (also
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`referred to herein as a batwing lens 10A)is rotationally sym-
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`metric aboutits longitudinal axis, and is batwing-shaped in a
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`cross-section that includes the longitudinal axis. The lens
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`10A receives relatively narrow light 11 from an LED module
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`(not shown). Through a variety ofreflections, refractions and,
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`optionally, scattering from the various surface features, the
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`lens 10A producesa relatively wide outputlight distribution
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`12, which includesa full 360 degrees.
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`Note that the term “batwing”as used herein describes the
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`shape of the cross-section of the lens itself, not an angular
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`output from the lens. There are instances in the literature
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`where “batwing lens” describes a lens that directs light
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`strongly into two preferred directions (in cross-section), each
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`ona side of a longitudinal axis; this is not the intended use of
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`the term in the present application.
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`FIG. 8 is a cross-sectional schematic drawing of the
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`batwing lens 10A of FIG. 7, along with the LED module 3.
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`There are many features on this lens 10A, and they are
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`described below in order, starting at the LED module 3 and
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`moving outward around the perimeter of the lens 10A.
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`For the purposes of this document, the side of the lens 10A
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`facing the LED module 3 maybereferred to as the “proximal”
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`US 8,449,150 B2
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`6
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`or “near” side, and thelens of the lens 10A facing away from
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`the LED module 3 maybereferred to as the “distal” or “far”
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`The LED module 3 shown in FIG.8 is intended to be a
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`generic LED module 3, which may be made by any numberof
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`manufacturers. Because a primary application for the lens
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`10A is for an incandescent light bulb, it is preferred that the
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`LED module 3 emit white light. Alternatively, the lens may be
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`used with an LED module having only a single color, or a
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`plurality of discrete colors.
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`The white light in the LED maybe generated in a number
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`of ways. In somecases, the LED module includesa chip that
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`emits light at a relatively short wavelength, such as blue,
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`violet, or ultraviolet (UV). The blue LEDs have wavelengths
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`that are typically in the range of about 440 nm to about 470
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`nm.Violet and UV LEDshaveshorter wavelengths. A phos-
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`phor absorbs the short-wavelength light and emits wave-
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`length-converted light, which can resemble white-light for
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`illumination purposes. The specific color properties of the
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`wavelength-converted light are largely determined by the
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`chemical properties ofthe phosphorandthe interaction ofthe
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`phosphor with the short-wavelength light.
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`In somecases, the phosphoris located at the LED chip, so
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`that the emission point of the wavelength-converted lightis
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`near the center of the hemisphere 9 (as opposed to being
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`evenly distributed over the curved surface of the hemisphere,
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`for instance). In some cases, the hemisphere 9 that encapsu-
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`lates all the LED chips may bereplaced with an individual
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`lens on each LED chip.
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`The lens 10A includes a concaveportion 29 onits proximal
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`face, which is centered on the longitudinal axis 39 of the lens
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`10A.In someapplications, the concave portion 29 is a hemi-
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`sphere(also referred to herein as a concave hemisphere 29). It
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`is expected that the batwing lens 10A should be able to
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`accommodate manydifferent configurations ofLED modules
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`3, including many of the commonly sized LED hemispheres,
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`so the precise configuration of the LED module 3 becomes
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`relatively unimportant. In general,
`it may be desirable to
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`situate the emission point of the LEDsat or nearthe center of
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`this concave hemisphere 29, so that the rays that leave the
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`LED module 3 strike the concave hemisphere 29 at roughly
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`normal incidence, and therefore do not significantly bend
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`portion 29 maybeanti-reflection coated, such as with a quar-
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`ter-wave of low-refractive index material, or may be left
`uncoated.
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`Adjacent to the hemispherical gap is a ridge 31. The ridge
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`31 maybe roughly parallel to the LED module 3 (or, equiva-
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`lently in this document, perpendicular to the longitudinal axis
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`39 of the lens 10A). In some cases, the ridge 31 is straight,
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`although the ridge 31 may optionally have some curvature.
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`The ridge 31 may be used for mechanical purposes in
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`attaching the lens 10A to the LED module3. Forinstance, the
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`ridge 31 maybe forced into contact with the circuit board of
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`the LED module 3, or a corresponding mechanicalpart on the
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`circuit board, where the contact determines a longitudinal
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`spacing between the lens 10A and the LED emission plane.
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`Alternatively, there may be additional legs attached to the
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`ridge 31 that may be used for spacing. Once a longitudinal
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`spacing has been determined, the lens 10A and LED module
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`3 are fixed to each other by gluing, soldering, welding,