WO2008080165A2 - Ensembles optiques de collimation à diodes électroluminescentes primaires multiples - Google Patents

Ensembles optiques de collimation à diodes électroluminescentes primaires multiples Download PDF

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Publication number
WO2008080165A2
WO2008080165A2 PCT/US2007/088812 US2007088812W WO2008080165A2 WO 2008080165 A2 WO2008080165 A2 WO 2008080165A2 US 2007088812 W US2007088812 W US 2007088812W WO 2008080165 A2 WO2008080165 A2 WO 2008080165A2
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WIPO (PCT)
Prior art keywords
light
collimation lens
spline
tir
lenslet array
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PCT/US2007/088812
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English (en)
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WO2008080165A3 (fr
Inventor
Edward Bailey
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Lighting Science Group Corporation
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Application filed by Lighting Science Group Corporation filed Critical Lighting Science Group Corporation
Priority to EP07869896A priority Critical patent/EP2100182A4/fr
Publication of WO2008080165A2 publication Critical patent/WO2008080165A2/fr
Publication of WO2008080165A3 publication Critical patent/WO2008080165A3/fr

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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B3/00—Simple or compound lenses
    • G02B3/0006—Arrays
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21K—NON-ELECTRIC LIGHT SOURCES USING LUMINESCENCE; LIGHT SOURCES USING ELECTROCHEMILUMINESCENCE; LIGHT SOURCES USING CHARGES OF COMBUSTIBLE MATERIAL; LIGHT SOURCES USING SEMICONDUCTOR DEVICES AS LIGHT-GENERATING ELEMENTS; LIGHT SOURCES NOT OTHERWISE PROVIDED FOR
    • F21K9/00—Light sources using semiconductor devices as light-generating elements, e.g. using light-emitting diodes [LED] or lasers
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B17/00—Systems with reflecting surfaces, with or without refracting elements
    • G02B17/08—Catadioptric systems
    • G02B17/0856—Catadioptric systems comprising a refractive element with a reflective surface, the reflection taking place inside the element, e.g. Mangin mirrors
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B19/00—Condensers, e.g. light collectors or similar non-imaging optics
    • G02B19/0004—Condensers, e.g. light collectors or similar non-imaging optics characterised by the optical means employed
    • G02B19/0028—Condensers, e.g. light collectors or similar non-imaging optics characterised by the optical means employed refractive and reflective surfaces, e.g. non-imaging catadioptric systems
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B19/00—Condensers, e.g. light collectors or similar non-imaging optics
    • G02B19/0033—Condensers, e.g. light collectors or similar non-imaging optics characterised by the use
    • G02B19/0047—Condensers, e.g. light collectors or similar non-imaging optics characterised by the use for use with a light source
    • G02B19/0061—Condensers, e.g. light collectors or similar non-imaging optics characterised by the use for use with a light source the light source comprising a LED
    • G02B19/0066—Condensers, e.g. light collectors or similar non-imaging optics characterised by the use for use with a light source the light source comprising a LED in the form of an LED array
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/09—Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for
    • G02B27/0938—Using specific optical elements
    • G02B27/095—Refractive optical elements
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/09—Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for
    • G02B27/0938—Using specific optical elements
    • G02B27/0994—Fibers, light pipes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/48—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
    • H01L33/58—Optical field-shaping elements

Definitions

  • This invention relates to optical devices. More specifically, the present invention relates to multicolor optical light source assemblies that produce an emitted light collimated to a narrow beam, while achieving acceptable color uniformity.
  • LEDs can be produced having a variety of colors.
  • a composite emitted light can be made by grouping LEDs of various combinations of colors in close physical proximity, with each LED individually emitting at a selectable intensity.
  • the LEDs may also be placed in a reflective cavity that is shaped to enhance control over the direction of the composite light.
  • the composite light may be used, for instance, for artistic, theatrical, or display purposes.
  • light from the individual LEDs historically has been difficult to collimate to a narrow beam, thereby producing a composite light having poor color uniformity.
  • Collimation and beam width are related terms, in which a highly collimated beam necessarily is a beam that has a narrow beam width compared to a beam that is not highly collimated.
  • a directed light beam is light emitted in a preferred direction, and can be characterized by beam angle and dispersion.
  • Beam angle refers to the full beam dispersion angle at half the maximum on-axis luminous intensity.
  • Intensity dispersion is a measure of the distribution of light over an angle with respect to the center of the light beam. Specialized lighting applications such as those identified above can benefit from having the ability to project a directed light beam of a composite of colors over a long distance. The distance of projection is increased when the emitted light is concentrated into a small beam angle.
  • Figure 1 is a top view of LED placement locations within a conventional light engine cavity, in which "B” indicates a blue excitation emitter with wavelength 440 - 495 nm, “R” indicates a direct emission red, orange, or amber with wavelength range 575 - 680 nm, and “G” indicates a direct emission green wavelength having a range 495 nm - 575 nm.
  • the LEDs are typically mounted on a substrate 1 which provides electrical connections, thermal dissipation, and mechanical support.
  • LED spacing within the light engine limits the minimum distance at which the light engine can be located from the target of its illumination, because too small a distance from the target of illumination produces poor composite color uniformity illumination of a close-in target.
  • Typical spacing between the individual LEDs is approximately 0.2032 millimeters as shown but may vary by as much as +0.5mm or more. Color mixing improves as LED spacing is reduced, but equipment or speed of manufacture limit how close together the LEDs may be placed, causing conventional multi-colored light engines like that shown in Figure 1 to suffer from poor color mixing.
  • Light engines are designed with the LEDs spaced relatively widely apart for improved heat dissipation, thereby causing poor color mixing. Viewers may see the poor color mixing as changes in the perceived light color from the light engine when viewed from different viewing angles.
  • Optical devices for controlled color mixing developed by the applicant are known and described in commonly-assigned U.S. Patent Application Serial Number 11/737,101, the entire content of which is incorporated by reference herein in its entirety. Second, fabrication machines and techniques may limit the minimum distance the LED die can be placed on the substrate.
  • FIG. 1 Light from an emitter like that of Figure 1 is conventionally passed through a rotationally- symmetric passive optic collimator in order to control the direction of light rays emitted by the engine.
  • Figure 2 is an illustration of the close-in beam illuminance pattern resulting from passing the light emitted by the light engine of Figure 1 through a rotationally symmetric total internal reflection (TIR) secondary optical lens.
  • TIR total internal reflection
  • the illuminated area does not have the desired uniformity of illumination, but instead has multiple colors illuminated.
  • the red, green and blue primary colors emitted by the individual LEDs are focused in different locations in the field.
  • the area of poor color uniformity may include any non-desired combination of colors emitted by the individual LEDs, and may be in any portion of the illuminated area, and the region may be of any shape. This separation of the colors is not desirable for some applications.
  • Multi-primary LED collimation optic assemblies are presented which are able to produce a light beam having improved collimation and color uniformity compared to conventional assemblies.
  • Light emitted by the LEDs passes through an optical assembly which may include the optical features of a spline patch inner lens, at least two lenslet arrays, a rippled reflector, and at least one secondary collimation lens.
  • the spline patch inner lens, TIR lens and at least one lenslet array are shaped to match the placement of the LEDs within the light engine. Surface details of the optical components improve the collimation, efficiency and color uniformity of the light passing through the light guide.
  • a second embodiment of the optical assembly includes a ribbed light guide and a collimation reflector.
  • a device in accordance with an embodiment of the present invention preferably includes one or more of the following assembly design features or functions:
  • FIG. 1 is a top view of LED placement locations within a conventional light engine cavity.
  • FIG. 2 is a beam pattern as projected on an observation screen resulting from rotationally symmetric TIR optics.
  • FIG. 3 is a side view of a first embodiment of the optic assembly.
  • FIG. 4A is a side view in the Z-X plane of a multi-lobe collimation TIR lens.
  • FIGS. 4B-4F present cross-sectional views of the multi-lobe collimation TIR lens, in the X-Y plane at various heights in the Z axis, indicating multiple lobes and profiles.
  • FIG. 5 is a side view of the inner collimation lens in the shape of a free form -b- spline patch.
  • FIGS. 6A - 6B are a side view and top view, respectively, of the first lenslet structure having hexagonal unit cells which are joined to produce a solid geometry and arrayed in a predetermined configuration to enhance color uniformity.
  • FIG. 6C is a top view of the first lenslet structure, further incorporating spherical lenses placed in randomized spatial locations .
  • FIG. 7A is a side view of an embodiment of a reflector used for collimation having improved color uniformity in which uniformity enhancement devices may include texturing or ripples.
  • FIG. 7B is an XY cross section of the reflector of FIG. 7A having color uniformity enhancement ripples.
  • FIG. 8 is a side view of a secondary collimation lens having an aspheric polynomial sag profile.
  • FIGS. 9 A - 9B are a side view and top view, respectively, of the secondary lenslet array having randomized spherical lenslets to improve color uniformity.
  • FIG. 10 is a side view of a second embodiment of the optic assembly.
  • FIG. 11 is a side view of a light guide having an exterior ribbed wall surface to increase color uniformity of multi-primary light engine.
  • FIGS. 12A - 12B are cross-sectional views of the light guide of FIG. 11, viewed at the light entrance (FIG. 12A) and at the light exit (FIG. 12B).
  • FIG. 13 is series of measured light beam uniformities associated with ribs in the light guide of varying degrees of ripple angle.
  • FIG. 14 is a perspective view of the second lenslet array attached to the exit port of a lightguide to improve color uniformity, the secondary reflector used to reduce intensity dispersion and the secondary lens used to provide beam edge control.
  • FIG. 15 is a top view of a lenslet array, located at the exit port of the ridged lightguide, having randomized lenslet size, shape and placement.
  • FIG. 16 is a side schematic view of the secondary collimation reflector and secondary edge control lens with convex side facing the incident light.
  • FIG. 17 is another side schematic view of the second collimation reflector and lens, enhanced to show the lens with an aspheric polynomial sag profile.
  • the present invention is directed to an optical assembly which performs the dual function of collimation and color homogenization or mixing.
  • the optical assembly disclosed is specifically tailored to match the placement of the solid-state emitters making up the light engine or light producing element.
  • the light engine is the 6-LED assembly shown in Figure 1.
  • the red LEDs are driven with 4.8 volts/ 0.35 amperes; green LEDs are driven with 7.4 volts/ 0.35 amperes; and blue LEDs are driven with 7.9 volts/ 0.35 amperes.
  • the individual LEDs produce a relatively wide lambertian 130° beam angle.
  • Figure 3 shows a first embodiment of the entire assembly, having the following features designed to enhance the collimation and mixing of light, with each of these features discussed in greater detail below: light engine 1 having a plurality of LEDs; LED light extraction lens 8; transmissive inner spline wall 2; free-form spline patch inner collimation lens 2a; multi-lobe TIR collimation lens 3; primary mixing lenslet array 4 fabricated in a primary mixing lenslet array body; b- spline profile reflector 5; secondary lenslet array 6; secondary collimation lens 7.
  • the light engine 1 has a plurality of LEDs and is preferably the light engine shown in Figure 1.
  • Figure 4a is an expanded view of the bottom portion of Figure 3, showing the portion of the assembly where the light is generated and initially controlled.
  • the light engine 1 in Figure 4a is shown in a side view with three LEDs Ia visible.
  • the light initially passes through a light extraction lens 8 which is generally a convex dome structure encapsulating the LEDs, made of a glass or high index silicone material which aids the transfer efficiency of the light from the LED and light extraction lens to the air.
  • a silicone encapsulant aids the extraction of light from the high index LED semiconductor.
  • spline patch lens Refracted light rays emerging from the light extraction lens 8 that have a +30° or less angle between their direction of travel and the Z-axis encounter a free- form spline patch inner collimation lens 2a ("spline patch lens"), in which "free- form” refers to a lens which lacks a center of rotation and having a surface described as a general surface polynomial or b-spline surface.
  • the spline patch lens 2a acts to improve the collimation and color uniformity of the light.
  • the cross-sectional shape of the spline patch lens 2a is tailored to the specific layout of LEDs within the light engine, for instance the light engine shown in Figure 1.
  • Tailoring refers to the guidance of light, which originated from extended sources at specific spatial locations, the sources having a prescribed emission intensity distribution, by the means of refractive, reflective, or diffractive means. Tailoring can include three dimensional redirection of light paths, for the purpose of collimating or redistributing light to improve uniformity. Light tailoring is performed through Monte-Carlo raytracing using extended sources.
  • Discovery of the preferred shape of the spline patch lens 2a or wall of multi-lobe TIR collimation lens 3 is performed through repeated perturbation of the surface shape of the spline patch lens 2a or profiles of the collimation lens 3 at a section in Z, calculation of the merit function and repeating this process with a slightly perturbed shape of spline patch lens 2a or wall of multi-lobe TIR collimation lens 3, until a shape is found having a sufficiently high merit function in which the merit function includes both collimation and uniformity elements.
  • Merit functions are described in E. Bailey, Narrow Beam RGB Array Optic, Proceedings of the SPIE, Volume 6669, pp. 666917 (2007), the entire content of which is hereby incorporated by reference in its entirety.
  • the resulting spline patch lens 2a and multi- lobe TIR collimation lens 3 provide improved collimation of the light through refraction.
  • the spline patch lens 2a has a vertical cross-sectional shape of a spline, for instance a Bezier curve or b-spline.
  • a b-spline surface can be described by:
  • S(u,v) is the b-spline surface defined by an array of control points in the u and v directions in which k and / are the orders of the b-spline surface in both directions
  • P contains an array of control points in which n represents the index of the control point in the u direction and m the index of the control point in the v direction
  • N* (u t ) defines the polynomial b-spline basis function of degree i through k in the u direction whereas N 1 Av ) are the basis functions of degree j through / in the v direction.
  • B-spline patch control points U 1 -U 3 and V 1 -V 3 are given by:
  • Figure 5 is an expanded view of the bottom portion of Figure 4a, showing the light extraction lens 8, free-form spline patch lens 2a, and transmissive inner spline wall 2.
  • any light emerging from the light extraction lens 8 having a larger than desired off- axis angle will illuminate the interior of the transmissive inner spline wall 2 and then reflect upward through the function of the multi-lobe TIR collimation lens 3 ("collimation lens").
  • the purpose of the collimation lens 3 is to further improve the collimation of the light after it exits from the transmissive inner spline wall 2.
  • the collimation lens 3 has an exit aperture at the top.
  • the desired collimation must be balanced with the desired degree of color and intensity homogeneity for the intended application.
  • collimation resulting in a relatively narrow beam angle of 16° provides the preferred balance, largely limited by the diagonal distance from the center of the light engine array to the edge of the outer LED emitter, and the lambertian intensity distribution of the light sources themselves.
  • the collimation lens 3 is a diamond turned or micro-EDM ("electrical discharge machined") PMMA acrylic, glass or other optically transparent dielectric which collimates light through the means of total internal reflection.
  • the cross- sectional shape of the collimation lens 3 includes lobes 3a ( Figure 4b) patterned to the placement of LEDs Ia within the light engine 1, and generally lacks rotational symmetry around the Z-axis.
  • the lobes 3a are rounded protrusions in the cross- sectional shape of the collimation lens 3, which act to direct the off-axis light emerging from the light emitters, thereby yielding the efficiency required to increase on-axis illuminance.
  • the collimation lens 3 geometry required to redirect the light depends on the light fields emerging from each of the LED emitters Ia, which is dependent on the internal quantum structures and textures of the LED itself. Texturing of the physical top surface of the LED is used to increase external quantum efficiency.
  • the shape of the collimation lens 3 is designed through light raytracing and geometry deformation iterations.
  • the lobe shape of the entire collimation lens 3 is roughly defined by placing one rotationally symmetric collimator centered over each of the six emitters Ia and combining the shape (i.e., "solid geometry") of each collimator into one composite lens.
  • the solid geometry of the composite lens is shaped to smoothly blend from the lobed structures 3a near the light engine 1, more conformal to LED Ia placement, to a circular shape at the exit aperture of the collimation lens 3.
  • This progression in cross-sectional shapes is seen in Figures 4B-4F, at increasing heights in the Z-axis, blending from a multi-lobe structure at the bottom ( Figure 4b) to an approximately circular symmetry (Figure 4f) at the exit aperture at the top.
  • a circular exit aperture is preferred because continuing the lobes 3a to the exit aperture would degrade illumination uniformity over the beam width.
  • Each of the lenslet arrays used in a preferred embodiment of the present invention provide a design individually tailored to the application of that lenslet array. Tailoring refers to the design procedure of determining the optimal amount of sag to disperse the light rays without backreflection TIR loss. For example a lenslet with a diameter of 2mm which has a sag depth of lmm will have substantial light backreflection which produces loss of light transfer.
  • the primary mixing lenslet array 4 operates in a similar fashion to the compound eyes of a fly.
  • the single lens of the human eye focuses light on the fovea of the retina.
  • the segmented compound eyes of a fly have a plurality of lenslets which focus light through many rhabdoms to photoreceptors. These structures or ommatidia are distributed over the compound eye.
  • the fly's eye lenslet array 4 analogously makes the light from a single light source appear to be emanating from a plurality of light sources.
  • the lenslets introduce micro-caustics, i.e., severe aberration-induced concentrations of light, which serve to disperse the light from the light sources to produce a more homogenous mixed light.
  • the performance of imaging optics is improved by reducing aberrations
  • the lenslet array 4 acts generally to improve the color mixing by using non-imaging optics, in which homogenization of the emitted light is improved by introducing severe aberrations caused by the lenslets.
  • Figure 6a is an expanded side view of the top portion of the primary mixing lenslet array body 4a, showing the lenslet array 4 contained within the top surface region of the multi-lobe primary TIR collimation lens 3.
  • Figure 6b is a top view of the lenslet array 4, showing an embodiment of the arrangement of the individual lenslets 4b within the lenslet array 4 (for sake of clarity, not all individual lenslets 4b are labeled).
  • Randomized spherical lenslets are a preferred surface shape, but an aspherical surface shape may also be used. Aspherics may contain conic constants, and other polynomial coefficients to finely control the shape of the generally spherical lens shape.
  • a global Zernike deformation of the lenslet array 4 may also be applied to the exit surface.
  • a Voronoi connectedness between the individual lenslets 4b provides spatial uniformity enhancement through local ray bundle dispersion.
  • Local ray bundle dispersion is a characteristic wherein a group of light rays which are nearly parallel (i.e., forming a bundle of rays) impinge a surface nearly at the same location with nearly the same angle of incidence; however the reflection of individual light rays within the bundle from the surface is over a wide range of angles of reflection.
  • Micro -surface roughness may be applied to sections of the lenslet array 4 in which the local surface perturbation can be described by a Gaussian, cosine, or periodic sine function.
  • lenslets 4b may be placed in a spiral hex pattern as shown in Figure 6b.
  • the lenslets 4b may be placed in a randomized manner throughout the top surface area of the primary mixing lenslet array body 4a, as shown in Figure 6c
  • the spline profile reflector 5 also includes a ribbed structure embedded within the lower portion of its vertical side walls, near the entrance aperture.
  • the ribbed structures are generally oriented in a vertical direction. The length, angle, depth and number of ribs are selected to optimize efficiency and color uniformity, and to provide the desired balance of collimation and uniformity.
  • the optimal length of the ridged section of the spline profile reflector 5 is determined through optical raytracing in which a balance between uniformity and light transfer loss is achieved. Finer ridges produce greater uniformity at the expense of manufacturability.
  • the ridge valleys may have a radius as small as 0.1mm.
  • Figure 7a is a cross-sectional view in the X-Z plane of an exemplary calculated shape of the spline profile reflector 5.
  • the spline profile reflector 5 is made up of a plurality of prescriptions, in which a prescription refers to a description of the shape (e.g., spline and its control points), structure (e.g., rib size and quantity), and texture (e.g., specular or diffuse) of a horizontal ring-shaped portion 18 of the spline profile reflector 5.
  • a prescription refers to a description of the shape (e.g., spline and its control points), structure (e.g., rib size and quantity), and texture (e.g., specular or diffuse) of a horizontal ring-shaped portion 18 of the spline profile reflector 5.
  • the inner surface of the spline profile reflector 5 is adapted to blend smoothly from one prescription to the next. Blending is performed through commonly available computer aided solid geometry tools, such as Solidworks, Pro/Engineer, or Rhino3D.
  • Figure 7a is shown with twenty prescriptions 18, but may generally range from 1 - 40 prescriptions
  • Figure 7b is a cross-sectional view of the spline profile reflector 5 in the X-Y plane, showing the ripple in the first prescription.
  • the ribbed structure tends to enhance the color uniformity of the reflected light by scattering the reflections in a wide angle in the X-Y plane. In the Z direction the ribbed structure helps collimates the light.
  • the ripple angle defines the kurtosis (i.e., degree of peakedness) of the ridge with respect to a surface tangent vector in which a 90° ripple would constitute a square wave function with vertical walls and a 0° ripple would be perceived as smooth and unperturbed with respect to amplitude.
  • Peak peak amplitude of ridge wave
  • the height of the spline profile reflector 5 is 40 mm, but may generally range from 10 mm - 100 mm. If the height is too small then the collimation will suffer, and if the height is too large then the compactness, cost, and manufacturability of the apparatus will suffer.
  • the ripple angle of the bottom prescription of the spline profile reflector 5 in Figure 7a is 50 degrees, but may generally range from 0 degrees - 90 degrees.
  • the ripple angle generally decreases from a lower prescription to a higher prescription along the Z axis.
  • a small ripple angle makes the reflective surface resemble a smooth surface, and if this occurs on a lower prescription then the color mixing will be degraded. If the ripple angle is too large, then some portion of the light will be reflected onto adjoining ripples, causing a loss in efficiency.
  • Ripple angle generally cannot exceed 90 degrees.
  • Figure 7b shows a cross-sectional view of the first profile, near the bottom of the spline reflector 5, having a relatively large ripple angle of approximately 55 degrees.
  • the number of ripples in Figure 7a of the bottom prescription of the spline profile reflector 5 is 180, but may generally range from 0 to 360.
  • the number of ripples generally decreases from a lower prescription to a higher prescription along the Z axis. If the number of ripples is too small on a lower prescription, the color mixing will be degraded. If the number of ripples is too large, ripple size and spacing must decrease and the manufacturability of the apparatus will suffer.
  • the ripple size and spacing is well above the size and spacing that would cause color separation due to diffraction effects.
  • the cross-sectional shape of the spline profile reflector 5 in the X-Y plane generally has an increasing radius with increasing height in the Z-axis because of the concave shape of the spline profile reflector 5.
  • the radius in Figure 7a in the X-Y plane at the bottom of the spline profile reflector 5 is 16.0mm, but may generally range from a lower limit sufficient to enclose the top of the TIR collimation lens 3 to about 35 mm or more.
  • the rippled entrance aperture of the spline reflector 5 is larger than the outside of the TIR primary collimation lens so as not to vignette (i.e., to clip) the light as it exits the lens.
  • the radius in the X-Y plane at the top of the spline profile reflector 5 is 23.5 mm, but may generally range from a lower limit that is greater than the radius at the bottom of the spline profile reflector 5, to about 40 mm or more. If the exit radius of the spline reflector 5 is too small, the light exiting the TIR collimation lens will back propagate and induce loss of light transfer efficiency. If the radius is too large, then the compactness, cost, and manufacturability of the apparatus will suffer as well as the collimation of the optical system.
  • An optional feature of the spline profile reflector 5 is a faceted reflective surface area. Facets are common in illumination reflectors to homogenize the light and to remove concentration areas, however the facets may adversely affect the collimation of the light. Facets are defined by discretizing the continuous curve of the inner surface of spline profile reflector 5 in both the X-Y and X-Z cross sections in which the +Z direction represents the light path originating from the source and ending at the receiver or observation plane.
  • light exiting the spline profile reflector 5 first passes through the secondary collimation lens 7, and then through the secondary lenslet array 6.
  • FIG. 9b A top view of an embodiment of the secondary lenslet array 6 is shown in Figure 9b.
  • This embodiment is shown with a lenslet radius of curvature of 2.25 mm, thickness of 0.35 mm, and 2,401 lenslets.
  • the lenslets cover the entire surface of the secondary lenslet array 6.
  • the secondary lenslet array 6 at the exit of the spline profile reflector 5 is tailored to further increase color and intensity homogeneity, and works in tandem with the primary lenslet array 4.
  • Randomized spherical lenslets are a preferred surface shape, but an aspherical surface shape may also be used.
  • the individual lenslets surface shape may include radii, radii+conics, aspherics, or multi- order polynomials.
  • the global surface of the lenslet array 6 may be perturbed by a general polynomial.
  • the outer perimeter of secondary collimation lens 7 is circular in the illustrated embodiment.
  • the thickness of the lenslets, the number of lenslets and their spatial locations may be optimized to provide sufficient uniformity at the highest collimation possible given the volume constraints.
  • the secondary collimation lens 7 further collimates the light and controls the edge of the beam or the degree to which the light falls off from the beam to field angle.
  • the opposite surface 7a of the secondary collimation lens 7 has a profile (i.e., curved surface) described by an aspheric polynomial sag equation, and is rotationally symmetric around the Z-axis.
  • Figure 10 shows another embodiment of the entire optical assembly, which shares elements from the first embodiment of the optical assembly, including: light engine 1 having a plurality of LEDs; LED light extraction lens 8; transmissive inner spline wall 2; free-form spline patch inner lens 2a; and the multi-lobe TIR collimation lens 3.
  • this alternate embodiment adds additional elements, including: lightguide 13; secondary lenslet array 14; reflector spline 15; aspheric lens 16 with curved surface 16a; and an optional tertiary lenslet array 17.
  • the profile of the lightguide 13 is a tapered shape, not comprised of a b- spline in the Z direction, and functions as a concentrator of the light from the entrance aperture to the smaller exit aperture.
  • Lightguides which are unnecessarily long quench light transfer efficiency, which results in reduced on-axis intensity.
  • the ridge pitch and angle to homogenize the light is preferably 45° - 55° for a taper angle which takes an original source from the exit of the multi-lobe TIR collimation lens 3 to an exit aperture of 8mm at the expense of increased light dispersion. Compensation for the increased light dispersion produced by the tapered lightguide 13 requires the additional reflector spline 15 to decrease light dispersion.
  • the light guide 13 is generally in the outer shape of a conic section, narrowing from the lower portion where the light enters the light guide 13, to the upper portion where the light exits the light guide.
  • Figure 11 shows an expanded view of the lightguide 13.
  • the lightguide 13 has TIR surfaces and preferably includes ribbing at the exterior walls. The ribbing generally oriented in a vertical direction causes protrusions on the inner surface of the lightguide 13. [0073]
  • the quality of the polishing of the ridges has a impacts the efficiency of light transfer from the primary collimation lens 3 through the secondary lenslet array at the exit of the lightguide.
  • the lightguide should also be manufactured from a PMMA acrylic or other optically transparent dielectric which provide high internal transmittance over length, preferably >99%/2mm.
  • the degree of polishing of the mold for manufacturing the ridged lightguide affects the internal efficiency of the light paths as they strike the dielectric/air interface.
  • Figures 12A - 12B show cross-sectional views of the light-guide 13 showing the ribbed structure of the walls for the profile near the entrance aperture (Figure 12A) and exit aperture ( Figure 12B).
  • the ribbing produces a sawtooth shape of the wall of the light-guide 13.
  • the rib angle refers to the angle between adjacent segments of the sawtooth shape of the wall.
  • the rib angle varies from 0° (i.e., completely smooth) to 90° (i.e., square wave).
  • the preferred design includes 120 ridges around the circumference of the lightguide, each having a rib angle of 50° - 55°. The number of ridges does not change over the length of the lightguide 13.
  • the inner and outer peaks of the ribbing form inner and outer envelopes of the cross- sectional shape.
  • Figure 13 shows simulated results of the effect of the rib angle upon the light uniformity at the exit of the lightguide 13.
  • Light uniformity can be characterized by the standard deviation of the light illuminance over the surface of the exit aperture. A lower standard deviation produces greater uniformity of the light intensity. Greater uniformity of light intensity is desirable for this application. Results are presented in the top row from 60° to 40° at 5° increments, and from 35° to 25° in the bottom row. The best uniformity is associated with ripple angles of 50° - 55°, but ripple angles of at least the range 40° - 60° provide light uniformity that works well.
  • FIG. 14 shows a perspective view of the secondary lenslet array 14.
  • individual lenslets may be arranged in a shape-randomized fly's eye lenslet structures, which may include changes in the radius of curvature of the lenslets across the array, or variable conies and aspheric coefficients which vary between two bounds. Sag variation refers to the surface shape of the lenslets.
  • the bounds of sag variation are the flat horizontal plane of the exit of the lightguide and the maximum thickness of the lenslets which does not cause the rays to recycle back to the source.
  • the perimeter shape of the lenslets may be non-spherical.
  • the placement and shape of the individual lenslets within the secondary lenslet array 14 are not necessarily the same as the placement and shape of the individual lenslets within any other lenslets in the invention, including the secondary lenslet array 14 of the first embodiment of the optical assembly.
  • the purpose of the secondary lenslet array 14 is to further enhance the color uniformity of the light.
  • the presence of the secondary lenslet array 14 at the end of the lightguide 13 reduces the length of lightguide 13 required to mix the light appropriately.
  • Figure 15 is a perspective view of another embodiment of the secondary lenslet array 14, showing a spherical lenslet array with constant radius -randomized with respect to x, y placement.
  • the entire surface area of the lenslet body is covered with lenslets.
  • the square boundary represents the design space for the lenslet array pattern, and the sawtooth circular area 18 within the square boundary represents the secondary lenslet array 14.
  • the edges of the square lenslet array aperture are trimmed away to match flush with the exit aperture ridges of the lightguide for manufacturing purposes.
  • the ridges 19 around the circumference of the sawtooth circular area 18 represent the ribbing within the walls of lightguide 13.
  • reflector spline 15 is a secondary collimation device, having a reflective inner surface with a cross-section in the X-Z plane in the shape of a concave b-spline.
  • the reflector spline 15 works in tandem with the secondary collimation lens 16 (described below) to produce a light beam having high intensity and acceptable color homogeneity within the beam angle, and having a sharp drop-off in intensity outside the beam angle.
  • the tertiary lenslet array 17 decreases efficiency by approximately 6%.
  • the aspheric lens 16 has two major surfaces: surface 16a is curved, with the curvature described by a sag profile.
  • the second major surface of the aspheric lens 16 is substantially flat, and cooperatively contacts the tertiary lenslet array 17. It is preferred that light strike the aspheric lens sag first before the planar side in order to improve the edge cut-off of the beam of light.
  • the sag profile of the aspheric lens 16, i.e., the curved surface extends within the cavity formed by the reflector spline 15.
  • the individual lenslets within the tertiary lenslet array 17 may be placed in a patterned arrangement or in a randomized arrangement.
  • Figure 16 is a detailed view of the secondary collimation reflector 15, having a cross-sectional shape in the X-Z plane of a b-spline.
  • Secondary aspheric lens 16 is shown above the secondary collimation reflector 15.
  • the height of the secondary collimation reflector 15 may range from 10 - 100 mm (34 mm typical); the radius of the entrance aperture 15a at the bottom may range from 1 - 10 mm (4 mm typical); the radius of the exit aperture 15b at the top is larger than the radius of the entrance aperture 15a, and may range from 15 - 50 mm (22.7 mm typical).
  • the vertical line 15c defines the optical axis of the secondary collimation reflector 15.
  • Figure 17 is a detailed view of the secondary lens 16 with aspheric sag profile along its curved surface 16a.
  • the radius of curvature of the curved surface 16a may range from a lower limit equal to the radius of the exit aperture 15b in the X- Y plane, with no upper limit (21 mm radius of curvature typical).
  • the curved surface 16a in Figure 17 is shown as a second order conic curve, but the curved surface 16a may be designed with additional aspheric coefficients in order to adjust the beam angle and the intensity distribution within the beam angle.
  • tertiary lenslet array 17 may be integrated with the secondary lens 16 to further enhance color uniformity.

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  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • General Engineering & Computer Science (AREA)
  • Non-Portable Lighting Devices Or Systems Thereof (AREA)
  • Optical Elements Other Than Lenses (AREA)

Abstract

La présente invention a trait à un ensemble optique qui permet d'améliorer l'uniformité des couleurs et d'améliorer la collimation d'une lumière produite par de multiples sources de lumière à diodes électroluminescentes dans un moteur de lumière. L'ensemble optique est spécifiquement conçu pour correspondre au positionnement des émetteurs à semi-conducteurs composant le moteur de lumière ou l'élément produisant de la lumière. Plus précisément, une lentille de collimation interne profilée à courbe spline de forme libre, ayant une forme de section transversale optimisée et des micro-crêtes, sert à disperser la lumière ; une lentille de collimation multilobée à rayonnement infrarouge thermique ayant une forme de section transversale optimisée et des micro-crêtes sert à disperser et redistribuer la phase ainsi qu'à assurer la collimation ; un réseau de microlentilles de mélange primaires ayant une surface optimisée servent à disperser la lumière provenant de l'émetteur de lumière ; un réflecteur à profil de spline mélange et collimate encore la lumière ; un réseau de microlentilles secondaires mélange encore la lumière ; et une lentille de collimation secondaire collimate encore la lumière.
PCT/US2007/088812 2006-12-22 2007-12-26 Ensembles optiques de collimation à diodes électroluminescentes primaires multiples WO2008080165A2 (fr)

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US60/871,581 2006-12-22

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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2195700A1 (fr) * 2007-10-01 2010-06-16 Lighting Science Group Corporation Optique de collimation rvb à réseau de del à sept cavités
US8038319B2 (en) 2008-05-28 2011-10-18 Lighting Science Group Corporation Luminaire and method of operation
EP2626728A3 (fr) * 2012-01-31 2017-01-04 Leuze electronic GmbH + Co KG Unité d'émission pour un capteur optique
WO2018184879A1 (fr) * 2017-04-03 2018-10-11 Philips Lighting Holding B.V. Création d'angle de faisceau large pour éclairage à semi-conducteur
WO2019022972A1 (fr) * 2017-07-28 2019-01-31 Fraen Corporation Optique de mélange de couleurs multi-del/multi-puce
US10429565B2 (en) 2012-11-08 2019-10-01 Fraen Corporation Multi-LED/multi-chip color mixing optics
WO2019201634A1 (fr) * 2018-04-19 2019-10-24 Signify Holding B.V. Dispositif d'éclairage
US11874541B2 (en) 2019-07-02 2024-01-16 Reald Spark, Llc Directional display apparatus
US12002789B2 (en) 2017-11-05 2024-06-04 Optovate Limited Display apparatus

Family Cites Families (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0580268A (ja) * 1991-06-28 1993-04-02 Toshiba Corp 光学装置及びその固定方法
JP3370612B2 (ja) * 1998-09-14 2003-01-27 富士通株式会社 光強度変換素子、コリメートレンズ、対物レンズ及び光学装置
US6637924B2 (en) * 2000-11-15 2003-10-28 Teledyne Lighting And Display Products, Inc. Strip lighting apparatus and method
US6560038B1 (en) * 2001-12-10 2003-05-06 Teledyne Lighting And Display Products, Inc. Light extraction from LEDs with light pipes
US7055967B2 (en) * 2002-05-17 2006-06-06 Bierhuizen Serge J A Illumination systems employing corrective optics for use in reduced étendue color video projection systems
US6724543B1 (en) * 2002-10-23 2004-04-20 Visteon Global Technologies, Inc. Light collection assembly having mixed conic shapes for use with various light emitting sources
US7006306B2 (en) * 2003-07-29 2006-02-28 Light Prescriptions Innovators, Llc Circumferentially emitting luminaires and lens-elements formed by transverse-axis profile-sweeps
US7390116B2 (en) * 2004-04-23 2008-06-24 Anvik Corporation High-brightness, compact illuminator with integrated optical elements
US7482567B2 (en) * 2004-09-24 2009-01-27 Koninklijke Philips Electronics N.V. Optical feedback system with improved accuracy
EP1805455B1 (fr) * 2004-10-18 2010-02-17 Koninklijke Philips Electronics N.V. Ensemble source lumineuse del haute efficacite
CA2620144A1 (fr) * 2005-04-06 2006-10-12 Tir Technology Lp Module d'eclairage dote de composants optiques de melange et de collimation de couleurs

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of EP2100182A4 *

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2195700A1 (fr) * 2007-10-01 2010-06-16 Lighting Science Group Corporation Optique de collimation rvb à réseau de del à sept cavités
EP2195700A4 (fr) * 2007-10-01 2014-03-19 Lighting Science Group Corp Optique de collimation rvb à réseau de del à sept cavités
US8038319B2 (en) 2008-05-28 2011-10-18 Lighting Science Group Corporation Luminaire and method of operation
EP2626728A3 (fr) * 2012-01-31 2017-01-04 Leuze electronic GmbH + Co KG Unité d'émission pour un capteur optique
US10429565B2 (en) 2012-11-08 2019-10-01 Fraen Corporation Multi-LED/multi-chip color mixing optics
WO2018184879A1 (fr) * 2017-04-03 2018-10-11 Philips Lighting Holding B.V. Création d'angle de faisceau large pour éclairage à semi-conducteur
CN110462453A (zh) * 2017-04-03 2019-11-15 昕诺飞控股有限公司 固态照明的宽光束角度创建
WO2019022972A1 (fr) * 2017-07-28 2019-01-31 Fraen Corporation Optique de mélange de couleurs multi-del/multi-puce
US12002789B2 (en) 2017-11-05 2024-06-04 Optovate Limited Display apparatus
WO2019201634A1 (fr) * 2018-04-19 2019-10-24 Signify Holding B.V. Dispositif d'éclairage
US11236888B2 (en) 2018-04-19 2022-02-01 Signify Holding B.V. Lighting device having light mixing optics and ring-shaped collimating structure
US11874541B2 (en) 2019-07-02 2024-01-16 Reald Spark, Llc Directional display apparatus

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EP2100182A4 (fr) 2012-01-04
WO2008080165A3 (fr) 2008-09-12
EP2100182A2 (fr) 2009-09-16

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