Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
  • F21V7/00—Reflectors for light sources
  • F21V7/0008—Reflectors for light sources providing for indirect lighting
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21S—NON-PORTABLE LIGHTING DEVICES; SYSTEMS THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLE EXTERIORS
  • F21S4/00—Lighting devices or systems using a string or strip of light sources
  • F21S4/20—Lighting devices or systems using a string or strip of light sources with light sources held by or within elongate supports
  • F21S4/28—Lighting devices or systems using a string or strip of light sources with light sources held by or within elongate supports rigid, e.g. LED bars
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
  • F21V7/00—Reflectors for light sources
  • F21V7/04—Optical design
  • F21V7/045—Optical design with spherical surface
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
  • F21V7/00—Reflectors for light sources
  • F21V7/04—Optical design
  • F21V7/06—Optical design with parabolic curvature
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
  • F21V7/00—Reflectors for light sources
  • F21V7/04—Optical design
  • F21V7/09—Optical design with a combination of different curvatures
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F21—LIGHTING
  • F21Y—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21S and F21V, RELATING TO THE FORM OR THE KIND OF THE LIGHT SOURCES OR OF THE COLOUR OF THE LIGHT EMITTED
  • F21Y2115/00—Light-generating elements of semiconductor light sources
  • F21Y2115/10—Light-emitting diodes [LED]

Definitions

• the present invention relates to the lighting arts. It especially relates to illuminators, spot lights, overhead lamps, and other light sources that employ a plurality of light emitting diodes, and to reflectors for such light sources, and will be described with particular reference thereto. However, the invention will also find application in conjunction with light sources that employ a plurality of light emitting elements other than light emitting diodes, such as miniature lamps, semiconductor lasers, and the like. The invention will still further find application in conjunction with reflectors for such other light sources.
• Conventional parabolic reflectors are designed for use in conjunction with a single, high brightness light emitting element such as an incandescent filament.
• the high brightness light emitting element is placed at a focal point of the reflector, and the parabolic reflector geometry causes light rays emanating from the focal point to be directed outward from the reflector opening or aperture as a generally collimated beam of light.
• Some beam divergence which may be desirable for certain applications, can be obtained by arranging the incandescent filament in a "defocused" position a selected distance away from the focus.
• a spherical reflector or other generally collimating reflector may be used instead ofthe parabolic reflector.
• a spherical reflector does not provide complete collimation, and so the beam produced using a spherical reflector has some divergence.
• Each Hght emitting diode is arranged at the focal point of its correspondi ⁇ g reflector, so that the Kght from each light emitting diode is formed into a collimated beam of Hght.
• this arrangement usually produces a granularized iUumination made up of a plurafity of collimated "beamlets" corresponding to the pluraHty of Hght emitting elements. Such granularized illumination may be undesirable for certain applications.
• the individual reflectors are arranged in an array or other closely packed configuration to provide cumulative iUvjumination. Such an arrangement may present manufacturing difficulties.
• the present invention contemplates an improved apparatus and method that overcomes the above-mentioned limitations and others.
• a reflector is disclosed.
• a sidewall defines a perimeter surrounding an interior region.
• a plurality of intersecting curved reflective surfaces are disposed in the interior region.
• Each curved reflective surface defines an off axis reflector segment having a focus disposed at the perimeter and oriented to reflect Hght emanating from its focus out a reflector aperture defined by the sidewall.
• a generally concave reflector includes a pluraHty of off axis reflector segments.
• a pluraHty of Hght emitting elements correspond to the pluraHty of off axis reflector segments.
• Each Hght emitting element is disposed at a focus of a corresponding off axis reflector segment and is arranged to illuminate that segment.
• a lamp is disclosed.
• a reflector includes a pluraHty of off-axis reflector segments each having a focus at a perimeter of the reflector.
• a pluraHty of light emitting elements are disposed at the foci ofthe off-axis reflector segments.
• the invention may take form in various components and arrangements of components, and in various process operations and arrangements of process operations.
• the drawings are only for purposes of iUustrating preferred embodiments and are not to be construed as limiting the invention.
• FIGURE 1 shows a perspective view of a generaUy circular reflector.
• FIGURE 2 shows a cross-sectional side view ofthe reflector of FIGURE 1.
• FIGURE 3 shows a perspective view of a Hght source including three Hght emitting diodes and the generaUy circular reflector of FIGURES 1 and 2.
• FIGURES 4A, 4B, 4C, and 4D show conceptuaUy how the reflector of FIGURES 1 and 2 is designed.
• FIGURE 5 shows a top view of a linear Hght source including a pluraHty of Hght emitting diodes and a rectangular reflector.
• FIGURE 6 shows a thin cross-sectional sHce of the linear Hght source of FIGURE 5.
• the thin slice S is indicated by dotted-dashed Hues in FIGURE 5.
• FIGURE 7 shows a top view of a square Hght source including four light emitting diodes and a square reflector.
• a lamp 8 includes a generally concave reflector 10 that has a generaUy circular perimeter 12 surrounding an interior region 14.
• Three intersecting off-axis reflector segments 20, 22, 24 are disposed in the interior region 14.
• the three off-axis reflector segments 20, 22, 24 define three lines of intersection 25, 26, 27.
• Intersection line 25 labeled in FIGURE 1 is defined by the intersection of reflector segments 20, 22.
• Intersection line 26 labeled in FIGURE 2 is defined by the intersection of reflector segments 22, 24.
• Intersection line 27 labeled in FIGURE 1 is defined by the intersection of reflector segments 20, 24.
• the off-axis reflector segments 20, 22, 24 can be off-axis paraboHc reflector segments, off-axis spherical reflector segments, another type of generally coUimating off-axis paraboHc reflector segment.
• the illustrated off-axis reflector segments 20, 22, 24 are substantiaUy sitmlar; however, the reflector segments can be different. For example, two segments can be parabolic while the third can be spherical.
• the off-axis reflector segments 20, 22, 24 each have a corresponding focus or focal position 30, 32, 34 disposed at the perimeter 12 ofthe reflector 10.
• a sidewaU 36 is disposed along the perimeter 12.
• An interior surface 38 of the sidewaU 36 supports Hght emitting elements 40, 42, 44 (shown in FIGURE 3) at about the focal positions 30, 32, 34, respectively.
• the light emitting elements 40, 42, 44 are Hght emitting diodes; however, miniature incandescent lamps or other compact Hght emitting elements can also be used.
• each off-axis reflector segment 20, 22, 24 is disposed at a portion of the perimeter 12 defined by or lying along the two other reflector segments 20, 22, 24.
• the focus 30 of the off-axis reflector segment 20 is disposed at a portion of the perimeter 12 defined by the off-axis reflector segments 22, 24;
• the focus 32 ofthe off-axis reflector segment 22 is disposed at a portion ofthe perimeter 12 defined by the off-axis reflector segments 20, 24;
• the focus 34 ofthe off-axis reflector segment 24 is disposed at a portion of the perimeter 12 defined by the off-axis reflector segments 20, 22.
• the reflector 10 and the Hght emitting elements 40, 42, 44 together define the lamp 8 Ulustrated in FIGURE 3.
• the Hght emitting element 40 at the focal position 30 of the off-axis reflector segment 20 iUuminates the reflector segment 20.
• this iUumination is indicated as a diverging cone of light emanating from the Hght emitting element 40, and the iUuminated area or footprint of the Hght on the corresponding off-axis reflector segment 20 is indicated.
• the collimated reflected beam of light is not Ulustrated.
• the Hght emitting element 42 at the focal position 32 of the off-axis reflector segment 22 iUirminates the reflector segment 22, and the light emitting element 44 at the focal position 34 of the off-axis reflector segment 24 iUuminates the reflector segment 24.
• the off-axis reflector segments 20, 22, 24 are paraboHc reflector segments defining the foci 30, 32, 34 and the Hght emitting elements 40, 42, 44 are substantiaUy point Hght sources precisely positioned at the foci 30, 32, 34, respectively.
• each Hght emitting element 40, 42, 44 and iUurn mating the respective reflector segment 20, 22, 24 is reflected outward from the generaUy concave reflector 10 as a collimated beam of Hght.
• the generally circular perimeter 12 corresponds to an aperture ofthe generaUy concave reflector 10.
• the collimating geometry is partiaUy relaxed, resulting in a diverging or otherwise incompletely colHmated beam of Hght.
• the Hght emitting elements 40, 42, 44 may be defocused relative to their respective off-axis reflector segments 20, 22, 24. Such defocusing is accompHshed in one embodiment by disposing the light emitting elements a selected distance away from their respective foci 30, 32, 34, to produce a diverging lamp illumination.
• the Hght emitting elements 40, 42, 44 in most embodiments are not perfect point light sources; rather, they generally have a finite size and thus some spatial spread of the light source. Such spatial spread also typically results in incomplete collimation and some beam divergence.
• the off-axis reflector segments may have a spherical or other non-paraboHc configuration that does not provide complete collimation even when the Hght emitting elements are positioned precisely at the foci.
• Relaxed coUimation geometries such as those just described may correspond to known tolerances of the manufacturing. For some appHcations, however, a diverging beam may be desired. For these appHcations, a relaxed collimation geometry is intentionally employed to obtain some beam divergence.
• FIGURE 4A With reference to FIGURES 4A, 4B, 4C, and 4D, a suitable conceptual approach for designing the reflector 10 is described.
• the design approach begins with a single conceptual on-axis paraboHc reflector 60 shown in FIGURE 4A.
• the paraboHc reflector 60 has a focus 62 lying on an axis of rotational symmetry of the paraboHc reflector 60.
• the generaUy circular perimeter 12 is selected such that it intersects the focus 62.
• a projection of the generaUy circular perimeter 12 onto the surface of the paraboHc reflector 60 defines a segment 62a of the paraboHc reflector 60.
• Also indicated in FIGURE 4B is a center 64 of the generaUy circular perimeter 12, and a projection line 66 connecting the center 64 with the projection ofthe center 64 onto the parabolic reflector segment 60.
• the off-axis reflector segment 20 is obtained by retaining only that portion ofthe segment 62a corresponding to an angular interval ⁇ ofthe generally circular perimeter 12. Because the reflector 10 includes three off-axis reflector segments 20, 22, 24, the angle ⁇ is selected as 120°. In general, for N off-axis reflector segments in a generaUy circular reflector using the present design approach, the angular interval ⁇ is selected as 360°/N. Thus, when designing for four off-axis reflector segments, an angular interval of 90° would be suitable.
• the portion 36a of the sidewaU 36 lying along the off-axis reflector segment 20 is defined by vertical projections from the perimeter 12 to the surface of the segment 62a of the paraboHc reflector 60.
• the remaining off-axis reflector segments 22, 24 are suitably designed by rotating the off-axis reflector segment 20 by 120° and by 240° about the center 64, respectively.
• the additional segments are suitably designed by rotating the first segment by 360°/N and integer multiples thereof.
• rotating the first reflector segment by 90°, 180°, and 270°, respectively would suitably position the other three off-axis reflector segments.
• the angular intervals for the segments are different.
• three angular intervals for example, three angular intervals of 100°, 120°, and 140° can be used.
• the total of the angular intervals should add up to 360° for a generally circular reflector.
• the reflector wiU not have an N-fold rotational symmetry.
• FIGURES 4A, 4B, 4C, and 4D Ulustrate a conceptual approach for designing the reflector 10.
• the reflector can be manufactured substantiaUy in accordance with the process Ulustrated in FIGURES 4A, 4B, 4C, and 4D, for example by starting with a physical reflector shaped as the on-axis paraboHc reflector 60, cutting out the off-axis reflector segment 20 from that physical reflector as indicated by FIGURES 4B and 4C, repeating the process to cut out off-axis reflector segments 22, 24, securing the three off-axis reflector segments 20, 22, 24 together by welding, brazing, or another joining technique, and forming the sidewaU 36 using shaped sheet metal or another process and a suitable joining technique.
• the reflector 10 is fabricated by injection molding using a pre-shaped mold die.
• the reflector 10 can be formed of plastic using injection molding, foUowed by deposition of a metal or another reflective layer or stack of layers onto the inner surface of the concave reflector 10 using vacuum evaporation, sputtering, or another suitable deposition method.
• the reflector 10 is formed from an aluminum or other metal blank that is shaped into the shape ofthe reflector 10 using a hydroform press with a punch element corresponding to the shape of the reflector 10.
• the light emitting elements 40, 42, 44 are suitably operated using a relatively high power input, and may dissipate substantial amounts of heat.
• the sidewaU 36, or at least the interior surface 38 thereof is substantiaUy thermaUy conductive and provides heat sinking, or at least a thermally conductive heat removal pathway, for the Hght emitting elements 40, 42, 44.
• radiative cooling may be sufficient and so the sidewaU 36 can be thermally insulating.
• the sidewaU 36 may include one or more printed circuit boards that support printed circuitry for feeding electrical power to the light emitting elements 40, 42, 44.
• planar printed circuit boards (not shown) can be mounted on the interior surface 38 of the sidewaU 36, or printed circuitry can be disposed directly onto the interior surface 38 of he sidewaU 36. In the latter arrangement, the interior surface 38 should be electricaUy insulating to provide electrical isolation for the printed circuitry.
• the Hght emitting elements 40, 42, 44 are electrically connected to wires passing through electrical vias (not shown) ofthe sidewaU 36.
• a Hght strip or lamp 108 includes a reflector 110 that has a generaUy rectangular perimeter 112 surrounding an interior 114. Ten intersecting off-axis reflector segments 120a, 120b are disposed in the interior region 114. The off-axis reflector segments 120 are arranged in two rows of five segments 120 each. The first row is made up of reflector segments 120a, which define a long side 112a ofthe rectangular perimeter 112. The second row is made up of reflector segments 120b, which define a long side 112b of the rectangular perimeter 112.
• the off-axis reflector segments 120a, 120b can be off-axis paraboHc reflector segments, off-axis spherical reflector segments, another type of generaUy coUimating off-axis parabolic reflector segment.
• the off-axis reflector segments 120a, 120b each have a corresponding focus or focal position disposed at the perimeter 112 of the reflector 110.
• An angled ledge 136a disposed at or near the long side 112a of perimeter 112 supports light emitting elements 140a disposed at about the focal positions ofthe off-axis reflector segments 120b, respectively.
• the Hght emitting elements 140a iUuminate the reflectors 120b, which reflect the iUtrmination as a generaUy collimated beam of Hght. Because the Hght emitting elements 140a positioned at about the focus positions of reflector segments 120b, the reflected Hght is generaUy colHmated. However, incomplete coUimation may be present, leading for example to a diverging reflected beam as Ulustrated by dotted lines in FIGURE 6.
• Incomplete coUimation can be intentionally designed, for example by positioning the Hght emitting elements 140a a selected distance away from the focal positions ofthe off-axis reflector segments 120b, or by using spherical or other non-paraboHc off-axis reflector segments that do not provide complete collimation.
• an angled ledge 136b disposed at or near the long side 112b of perimeter 112 supports light emitting elements 140b disposed at about the focal positions of the off-axis reflector segments 120a, respectively.
• the Hght emitting elements 140b iUuminate the reflectors 120a, which reflect the iUurnmation as a generaUy colHmated beam of Hght. Because the Hght emitting elements 140b are positioned at about the focus positions of reflector segments 120a, the reflected Hght is generaUy colHmated, although some beam divergence is optionaUy designed into the lamp.
• the angled ledges 136a, 136b may include printed circuit boards, printed circuitry, electrical vias, or other suitable structure for electricaUy connecting the Hght emitting elements 140a, 140b to electrical power.
• the light emitting elements 140 are Hght emitting diodes; however, miniature incandescent lamps or other compact light emitting elements can also be used.
• the reflector 110 and the Hght emitting elements 140 collectively define the lamp 108. While two rows each including five off-axis reflector elements are Ulustrated, it wiU be appreciated that fewer or additional off-axis reflector segments and corresponding Hght emitting elements can be included to produce a linear Hght strip of selected length.
• the reflector 110 can be designed using a procedure similar to that Ulustrated in FIGURES 4A-4D for the generally circular reflector 10.
• a suitable conceptual design approach for designing the reflector 110 is described with reference to one of the off-axis reflector segments 120b, which has its corresponding focal position designated as focus 162 in FIGURE 5.
• a conceptual on-axis parabolic reflector 160 corresponding to the focus 162 is indicated in FIGURE 5 by a dashed circle.
• Each of the other off-axis reflector segments 120a, 120b can simUarly be considered to have their focal positions designated as on-axis foci of conceptual on-axis paraboHc reflectors, which wUl overlap substantiaUy.
• the on-axis reflectors are trimmed at their intersections and are trimmed at about the generaUy rectangular aperture 112.
• Trim lines 126 for the example on-axis paraboHc reflector 160 are labeled as trim lines 126 in FIGURE 5.
• the long side 112a of perimeter 112 approximately passes through the focus 162 which serves as the off-axis focus for the off-axis reflector 120b bounded by the trim lines 126.
• the perimeter 112 corresponds to a rectangular aperture ofthe reflector 110.
• the reflector 110 can be fabricated in various ways, include sheet metal shaping, injection molding, hydroforming, and the like.
• a metal or other reflective coating can be deposited on the concave surfaces ofthe off-axis reflector segments 120a, 120b using vacuum evaporation, sputtering, or the like.
• a lamp 208 includes a reflector 210 that has a generaUy square perimeter 212 surrounding an interior 214.
• the off-axis reflector segments 220 are disposed in the interior region 214.
• the off-axis reflector segments 220 are arranged in a square.
• the off-axis reflector segments 220 can be off-axis paraboHc reflector segments, off-axis spherical reflector segments, another type of generally collimating off-axis paraboHc reflector segment.
• Each off-axis reflector segment 220 has a corresponding focus or focal position disposed at a corner of the generaUy square perimeter 212 across the reflector 210 from that off-axis reflector segment 220.
• Light emitting elements 240 such as Hght emitting diodes, miniature incandescent lamps, or the like, are disposed at about the focal positions. Each Hght emitting element 240 iUtrminates the off-axis reflector segment 220 disposed across the reflector 210 from that light emitting element 240, as indicated by dotted lines in FIGURE 7.
• the Hght emitting elements 240 can be mounted on sidewalls, ledges, or other support structures disposed at the corners of the perimeter 212.
• the light emitting elements 240 illuminate their respective off-axis reflector segments 220, which generaUy collimate and reflect the Hght out an aperture corresponding to the generally square perimeter 212.

Landscapes

• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Non-Portable Lighting Devices Or Systems Thereof (AREA)
• Optical Elements Other Than Lenses (AREA)
• Arrangement Of Elements, Cooling, Sealing, Or The Like Of Lighting Devices (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (2)

Family

ID=34861077

Family Applications (1)

Country Status (5)

Families Citing this family (37)

Family Cites Families (22)

• 2004
  • 2004-02-19 US US10/782,694 patent/US7040782B2/en not_active Expired - Lifetime
• 2005
  • 2005-02-18 WO PCT/US2005/005161 patent/WO2005079482A2/en not_active Ceased
  • 2005-02-18 EP EP05713773A patent/EP1720731A4/en not_active Withdrawn
  • 2005-02-18 JP JP2006554223A patent/JP4726808B2/ja not_active Expired - Fee Related
  • 2005-02-18 CN CNA200580009132XA patent/CN1933989A/zh active Pending

Also Published As

Similar Documents

Legal Events