具体实施方式：
[0033]Like reference numbers and designations in the various drawings indicate like elements.
DETAILED DESCRIPTION
[0034]The following detailed description is directed to certain implementations for the purposes of describing the innovative aspects. However, the teachings herein can be applied in a multitude of different ways. As will be apparent from the following description, the innovative aspects may be implemented in any device that is configured to provide illumination. More particularly, it is contemplated that the innovative aspects may be implemented in illumination systems, such as, a thin backlight and/or a frontlight unit configured to provide illumination to various display devices, such as, for example liquid crystal based display devices or LED based display devices. The described implementations may be implemented in any device, apparatus, or system that can be configured to display moving images, such as video, still images, such as photographs, text, graphics, and/or pictures. More particularly, it is contemplated that the described implementations may be included in or associated with a variety of electronic devices such as, but not limited to: mobile telephones, smart phones, multimedia Internet enabled cellular telephones, mobile television receivers, wireless devices, Bluetooth® devices, personal data assistants (PDAs), wireless electronic mail receivers, hand-held or portable computers, tablets, netbooks, notebooks, smartbooks, tablets, printers, copiers, scanners, facsimile devices, global positioning system (GPS) receivers/navigators, cameras, digital media players (such as MP3 players), camcorders, game consoles, wrist watches, clocks, calculators, television monitors, flat panel displays, electronic reading devices (e.g., e-readers), computer monitors, auto displays (including odometer and speedometer displays, etc.), cockpit controls and/or displays, camera view displays (such as the display of a rear view camera in a vehicle), electronic photographs, electronic billboards or signs, projectors, architectural structures, microwaves, refrigerators, stereo systems, cassette recorders or players, DVD players, CD players, VCRs, washers, dryers, washer/dryers, parking meters, billboards, signage, etc. Additionally, innovative aspects may be implemented in thin illumination systems and/or luminaires for commercial and/or residential lighting applications. For example, the embodiments described herein can be configured as slim profile lighting devices that can be incorporated in or used as a building material, such as, for example, walls, floors, ceilings of residential and commercial structures. Other uses are also possible.
[0035]Various embodiments of an optical component are described herein with reference to the accompanying figures. The terminology used in the description presented herein is not intended to be interpreted in any limited or restrictive manner, simply because it is being utilized in conjunction with a detailed description of certain specific embodiments. Furthermore, various embodiments of the optical component described herein can comprise several features, no single one of which is solely responsible for its desirable attributes or which is essential to achieve the light distribution profiles described herein.
[0036]The terms bottom, top and side are used in the present disclosure to designate or identify certain features described in the various implementations. However, these terms are used only to define relative positions of such features and should not be interpreted as carrying any meaning other than the relativity of positons of features reciting these terms.
[0037]Various embodiments of an optical component described herein can be configured to redistribute light emitted from a LED emitter. For example, the implementations of the optical component described herein can be configured to uniformly spread light emitted from the LED emitter over a wide angular range. Furthermore, the implementations of the optical component described herein can also be used to mix different wavelengths of light emitted from the LED emitter such that a high degree of color uniformity is achieved in the near field as well as the far field. Additionally, the implementations of the optical component described herein can also be configured to reduce peaks in the intensity distribution of light emitted from the LED emitter over an area of illumination such that the light intensity is nearly constant across the illumination area.
[0038]Various implementations described herein include a light bar including a plurality of LED emitters, each LED emitter associated with an optical component configured to tailor the radiation pattern of light emitted from the LED emitter to a desired radiation pattern. For example, the optical component associated with each LED emitter may be configured to spread the light emitted from the LED uniformly over a wide angular, reduce peaks in the intensity distribution of light emitted from the LED emitter and/or mix the different wavelengths emitted from the LED to reduce color non-uniformity.
LED Emitter
[0039]A light emitting diode (LED) is a semiconductor device that emits light in ultraviolet, visible and/or infrared wavelengths. Recent advances in semiconductor technology has led to the development of LEDs with high luminous efficacy that can generate light having the same amount of luminous flux as a standard 60 W or 100 W incandescent or fluorescent bulb with no more than 1 W of electrical power. LED emitters with high luminous efficacy can be miniaturized to have a size less than 10 mm such that they can be mounted on a printed circuit board (PCB) using semiconductor packaging techniques. The PCB can include driving circuits to supply required electrical current and voltage to the LED emitters. In various implementations, the PCB can also include heat sink and/or thermo-coolers to cool the LED emitters. Accordingly, a thin array of LED emitters that can provide a large amount of luminous flux using a small amount of electrical power can be manufactured. Such thin arrays of LED emitters are in great demand for a variety of display applications and/or lighting applications.
[0040]Early LED emitters primarily emitted light in the red and/or the infrared spectral range. However, recent developments in semiconductor technology have led to the development of LED emitters that can emit light in different regions of the ultraviolet (UV), visible and infrared (IR) spectrum. For example, LED emitters that can emit in the blue and violet regions of the visible spectrum have been developed recently. LED emitters that emit white light have also been developed. White LED (WLED) emitters can be realized in one of two ways. One method of producing a WLED emitter is to use LED emitters that emit contrasting colors and mix the contrasting colors. For example, a WLED emitter can include a cyan LED emitter and a yellow LED emitter such that light output from the cyan LED emitter and the yellow LED emitter are mixed to produce white light. As another example, a WLED emitter can include a red LED emitter, a green LED emitter and a blue LED emitter such that light output from the red, green and blue LED emitters can be mixed to produce white light. Another method of producing a WLED emitter is to use phosphor material that absorbs radiation and emits a white light. For example, a WLED emitted can include a RGB phosphor and a near-UV or a UV LED. The RGB phosphor can absorb the radiation from the near-UV or UV LED and emit a broad spectrum white light. As another example, a WLED emitted can include a yellow phosphor and a blue LED. The yellow phosphor can absorb the radiation from the blue LED and emit a broad spectrum white light.
[0041]LED emitters are desirable in backlights and frontlights for display devices as well as in lighting due to their high luminous efficacy, long lifetimes, low manufacturing cost and miniaturization capabilities.
[0042]LED emitters can generally be divided into two classes: side-emitting emitters and top-emitting emitters. In top-emitting LED emitters, light is emitted along a direction perpendicular to the surface of the LED emitter. In side-emitting LED emitters, light is emitted along a direction parallel to the surface of the LED. Most top-emitting LED emitters exhibit a Lambertian emission pattern, where the intensity profile is proportional to the cosine of the emission angle, which is measured from a normal to the surface of the LED emitter.
[0043]LED emitters usually emit light from a small area. For example, the emission area can be less than 1 mm2. Thus, optical components that can reflect, refract collimate, focus, diffuse and/or diffract light are integrated with the LED emitter to tailor the pattern of radiation emitted from the LED emitter.
[0044]Conventional optical elements that are configured to collect light from WLED emitters may not be capable of mixing the different wavelengths of light efficiently which may result in color non-uniformity at the illumination surface and/or at the surface of the optical component. For example, average correlated color temperature in a central portion of the illuminated region may be different than the average correlated color temperature in a peripheral portion of the illuminated region. Moreover, the average correlated color temperature in various portions of the illuminated region may be lower than the average color temperature of the LED emitter. Accordingly, it would be desirable to provide optical components that can spread light from LED emitters uniformly and/or monotonically and/or with higher degree of color uniformity.
[0045]Various implementations of light spreading and/or color mixing optical components described herein include one or more textured light input surfaces that are configured to receive different wavelengths of light emitted from the LED emitter and redirect the different wavelengths of light such that light output from the optical component and incident on an illumination surface disposed at an optical distance between about 10-30 mm has a high degree of color uniformity. For example, various implementations of optical component described herein include one or more textured light input surfaces that are configured to spatially mix different wavelengths of light emitted from the LED emitter such that a variation between a maximum correlated color temperature (CCT) and a minimum CCT is less than 60% of the maximum CCT. As another example, various implementations of optical component described herein include one or more textured light input surfaces that are configured to spatially mix different wavelengths of light emitted from the LED emitter such that an average CCT across the illumination surface is substantially similar to the average CCT of the LED emitter.
[0046]In various implementations of the light spreading and/or color mixing optical components described herein, one or more output surfaces can also be textured to improve color uniformity and/or to distribute light uniformly across the illumination surface.
Light Spreading and Color Mixing Optical Component
[0047]FIG. 1A illustrates a partially sectioned isometric view of an embodiment of an optical component 10 configured to spread light emitted from a LED emitter as well as mix different wavelengths of light emitted from the LED emitter. In various implementations, the optical component 10 can be configured to spread light emitted from the LED emitter uniformly across an illumination panel such that the intensity of light across the illumination panel is nearly constant. In various implementations, the optical component 10 can be configured to spread light emitted from the LED emitter across an illumination panel such that the such that the illuminance in a region located at a distance less than or equal to about 25 mm from a point where the central axis normal to the optical component intersects the panel is greater than 75% of the maximum illuminance on the illumination panel, when an area about the point where the central axis of the optical component intersects the illumination surface where the illuminance from a single LED coupled to the optical component falls to about 50% of the maximum illuminance is at least about 80 square cm (cm2). In various implementations, the optical component 10 can be configured such that the illuminance in a region located at a distance less than or equal to about 10 mm from a central axis normal to the optical component is greater than 80% of the maximum illuminance on the illumination panel. In various implementations, the optical component 10 can be configured such that the illuminance in a region located at a distance between about 20 mm and about 50 mm from a central axis normal to the optical component is between about 50% and about 90% of the maximum illuminance on the illumination panel. Without subscribing to any theory, as used herein, illuminance is a measure of the luminous flux incident per unit area of an illumination surface and can be correlated with the intensity of light incident per unit area of the illumination surface. In various implementations, the illuminance across the surface can be measured using a lux meter.
[0048]FIG. 1B illustrates a different partially sectioned isometric view of the embodiment of the optical element illustrated in FIG. 1A and FIG. 1C illustrates an isometric view of the embodiment of the optical component shown in FIG. 1A.
[0049]The optical component 10 can be disposed about a central axis 11. In various implementations, the optical component 10 can be rotationally symmetric about the central axis 11. Without any loss of generality, a direction along the central axis 11 can represent the vertical direction and a direction perpendicular to the central axis 11 can represent the horizontal direction. In implementations of the optical component 10 having a circular cross-section in a plane perpendicular to the central axis 11, the central axis 11 can pass through the center of the circular cross-section. In various implementations of the optical component 10, the central axis 11 can pass through the centroid of the optical component 10. In various implementations of the optical component 10, the central axis 11 can pass through a geometric center of the optical component 10.
[0050]Various implementations of the optical component 10 comprises a top surface 12, an inner cavity 13 bounded by an inner surface 13a, a bottom surface 19 opposite the top surface 12 and a side surface 17 joining the bottom surface 19 and the top surface 12. In various implementations, the optical component 10 can include one or more supporting posts 18 disposed along the bottom surface 19. The optical component 10 can be integrated with a reflector. For example, the optical component 10 can be disposed on the reflector such that the bottom surface 19 is adjacent the reflector. The reflector can comprise an opening that is configured to allow light from the LED emitter to be coupled into the optical component. The LED emitter can be disposed on a printed circuit board (PCB). In various implementations, one or more surfaces of the PCB adjacent the bottom surface 19 of the optical component 10 can be reflective. In such implementations, the reflective surface of the PCB can function as the reflector. Accordingly, a reflector need not be integrated with the bottom surface 19 of the optical component 10 in such implementations. The reflectivity of the reflector can affect the intensity of light in the region of the illumination surface directly overhead the optical component. Accordingly, the intensity of light across the illumination surface can be tailored by adjusting the reflectivity of the reflector integrated with the optical component 10. In various implementations, the reflector can be a diffused reflector. In various implementations, the surface of the reflector and/or the PCB adjacent the optical component can be textured to mix different wavelengths of light and/or to spread the light output from the optical component uniformly across the illumination surface.
[0051]The optical component 10 can have a maximum height between about 5-10 mm (e.g., about 5.5 mm, 6 mm, about 7 mm, about 8 mm, about 9 mm). A maximum lateral extent of the optical component 10 from the central axis can be between about 6-10 mm (e.g., about 7 mm, about 8 mm, about 9 mm). In implementations of the optical component 10 having a top surface 12 with a circular cross-section in a plane perpendicular to the central axis, the maximum diameter of the top surface 12 can be between about 12-20 mm (e.g., 13 mm, 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, 20 mm).
Textured Annular Structure
[0052]The optical component 10 can further include an annular structure 8 disposed about the side surface 17. In various implementations, the annular structure 8 can form a border between the top surface 12 and the side surface 17 as shown in FIGS. 1A-1C. Alternately, in some embodiments, the annular structure 8 can form a border between the bottom surface 19 and the side surface 17. In some implementations, the annular structure 8 can be in the mid-section of the side surface 17 such that it divides the side surface 17 into an upper portion and a lower portion. In some other implementations, the entire side surface 17 could be configured as the annular structure 8 such that a separate annular structure is not provided. The annular structure 8 can be continuous or include a plurality of discontinuous linear or curved segments. The annular structure 8 may be configured to alter the radiation pattern of the light emitted from a LED emitter disposed with respect to the optical component 10. In various implementations, the annular structure 8 can be integrated with the reflector and/or the PCB on which the LED emitter is disposed (for example, as shown in FIG. 3).
[0053]In the implementations illustrated in FIGS. 1A-1C, the annular structure 8 is configured as a ring that extends from the side surface 17 and surrounds the optical element 10. In the implementations illustrated in FIGS. 1A-1C, the annular structure 8 can be configured to form a lip or a rim. Accordingly, with reference to FIGS. 1A-1C, the annular structure 8 can be referred to as a ring step structure. As shown in FIGS. 1A-1C, the annular structure 8 includes a top surface 14, a side surface 15 and a bottom surface 16. However, in other implementations, the annular structure 8 can comprise less than or more than three surfaces. For example, in some implementations, the annular structure 8 may comprise only a side surface. As another example, in some implementations, the annular structure 8 may comprise only a top surface and a side surface. As yet another example, the annular structure 8 may comprise only a bottom surface and a side surface. In some other implementations, the annular structure 8 may comprise 4, 5, 6, 8 or 10 surfaces. Although, in FIGS. 1A-1C, the annular structure 8 is depicted as a ring, in other implementations, the annular structure 8 can be a partial ring structure.
[0054]In various implementations, one or more surfaces of the annular structure 8 can be partially or completely textured. Partial or complete texturing of one or more surfaces of the annular structure 8 can be accomplished by providing a plurality of microstructures 805. The plurality of microstructures 805 can include grooves, protrusions, facets, surface or volume holograms, gratings, etc. In various implementations, the plurality of microstructures can be arranged randomly. However, in other implementations, the plurality of microstructures can be arranged to form a regular or an irregular pattern. The plurality of microstructures can have a size between about 1 micron and about 1 mm. In various implementations, the density of the plurality of microstructures can be between 1000/mm2 and 1/mm2.
[0055]In various implementations, the density of the plurality of microstructures disposed on one or more surfaces of the annular structure 8 can be between 10/mm2 and 30/mm2, between 20/mm2 and 50/mm2, between 25/mm2 and 100/mm2, between 40/mm2 and 75/mm2, between 50/mm2 and 100/mm2, between 75/mm2 and 200/mm2, between 125/mm2 and 250/mm2, between 150/mm2 and 300/mm2, between 200/mm2 and 400/mm2, between 250/mm2 and 500/mm2, between 300/mm2 and 450/mm2, between 500/mm2 and 750/mm2, between 550/mm2 and 800/mm2, between 600/mm2 and 700/mm2, between 750/mm2 and 850/mm2, between 800/mm2 and 1000/mm2, or values therebetween.
[0056]In various implementations, the plurality of microstructures can have a size such that an individual microstructure is not resolved by a normal human eye without the aid of magnification. Each of the plurality of microstructures 805 can have a size in a range between 1 micron and about 100 microns. For example, in implementations where some of the plurality of microstructures 805 include grooves, a depth (or height) of grooves can be in the range between about 1 micron and about 10 microns, between about 5 micron and about 20 micron, between about 10 microns and about 30 microns, between about 30 microns and about 50 microns, between about 40 microns and about 75 microns, between about 50 microns and about 80 microns, between about 75 microns and about 100 microns, or values therebetween.
[0057]As another example, in implementations where some of the plurality of microstructures include facets, a height of the facets can be in the range between about 1 micron and about 10 microns, between about 5 micron and about 20 micron, between about 10 microns and about 30 microns, between about 30 microns and about 50 microns, between about 40 microns and about 75 microns, between about 50 microns and about 80 microns, between about 75 microns and about 100 microns, or values therebetween.
[0058]For example, in implementations where some of the plurality of microstructures include gratings, a depth of the gratings and/or the distance between two consecutive gratings can be in the range between about 1 micron and about 10 microns, between about 5 micron and about 20 micron, between about 10 microns and about 30 microns, between about 30 microns and about 50 microns, between about 40 microns and about 75 microns, between about 50 microns and about 80 microns, between about 75 microns and about 100 microns, or values therebetween.
Top Surface of the Optical Component
[0059]The top surface 12 can comprise a central portion 12a and a peripheral portion surrounding the central portion 12a. In various implementations, the top surface 12 can be planar or curved. For example, the top surface 12 can be concave, convex or an aspheric. In implementations of the optical component 10 wherein the top surface 12 is curved, the top surface 12 can be formed by a rotating a curved segment about the central axis 11. Accordingly, in such implementations, the top surface 12 can be rotationally symmetric about the central axis 11. In various implementations, the top surface 12 can appear to be dome shaped or bell shaped as viewed along the central axis 11 from a position above the top surface 12. In various implementations, the top surface 12 can be a part of a sphere such that a cross-section of the top surface 12 in a plane perpendicular to the central axis 11 is a circle. In various implementations, the top surface 12 can be a part of an ellipsoid such that a cross-section of the top surface 12 in a plane perpendicular to the central axis 11 is an ellipse. In some implementations, the top surface 12 can comprise a plurality of curved sections such that a cross-section of the top surface 12 in a plane perpendicular to the central axis 11 comprises a plurality of concave or convex curves. For example, the top surface 12 can comprise a plurality of curved sections such that a cross-section of the top surface 12 in a plane perpendicular to the central axis 11 has a flower shape.
[0060]In various implementations, the top surface 12 can be partially or entirely textured by providing a plurality of microstructures. The plurality of microstructures can include grooves, protrusions, facets, surface or volume holograms, gratings, etc. In various implementations, the plurality of microstructures can be arranged randomly. However, in other implementations, the plurality of microstructures can be arranged to form a regular or an irregular pattern. The density of the plurality of microstructures disposed on the top surface 12 can be between 1/mm2 and 1000/mm2. The ranges of the size and density of the microstructures disposed on the top surface 12 can be similar to the ranges provided above. The plurality of microstructures on the top surface 12 can further increase color mixing capability of the optical component 10. In some implementations, texturing the top surface 12 can reduce intensity spreading. In such implementations, the density of the plurality of microstructures can be adjusted to provide increased color mixing without significantly reducing the spread in the intensity of output light.
[0061]In various implementations, the curvature of the top surface 12 can be configured such that the central portion 12a is recessed such that a vertical distance between points in the central region 12a and the bottom surface 19 is shorter than a vertical distance between points outside the central region 12a (e.g., the peripheral region) and the bottom surface 19. For example, the central portion 12a can be shaped like a funnel or an inverted bell. In some such implementations, the top surface 12 can have a curvature such that an internal angle between a tangential line to the portion of the surface included in the central section 12a and the central axis 11 in air is less than 90 degrees and an internal angle between a tangential line to the portion of the surface outside the central section 12a and the central axis 11 is greater than 90 degrees.
Side Surface of the Optical Component
[0062]The side surface 17 of the optical component 10 can be formed by rotating a curved segment around the central axis 11. In various implementations, the side surface 17 can be configured as a cylindrical surface disposed about the central axis 11. Accordingly, in such implementations, the side surface 17 is rotationally symmetric about the central axis 11. In some embodiments, the side surface 17 may be configured to widen near the bottom surface 19 and narrow toward the top surface 12. Alternately, in some embodiments, the side surface 17 may be configured to narrow near the bottom surface 19 and widen toward the top surface 12.
Bottom Surface of the Optical Component
[0063]The bottom surface 19 can be planar or curved. For example, in various implementations, the bottom surface 19 can appear to be concave, convex or aspheric as viewed along the central axis 11. The bottom surface 19 can have a circular or elliptical cross-section in a plane perpendicular to the central axis 11. Alternately, in some implementations, the cross-section of the bottom surface 19 in a plane perpendicular to the central axis 11 can be a polygon. The bottom surface 19 can comprise a central region 22 and a peripheral region 20. The bottom surface 19 includes an opening 19a to the inner cavity 13. The opening 19a can be located in the central region of the bottom surface 19.
[0064]In various implementations, the peripheral region 20 can be inclined with respect to the central region 22. For example, in various implementations, the peripheral region 20 can be configured such that a tangential line to the peripheral region 20 forms an angle with respect to a tangential line to the central region 22. In various implementations, the peripheral region 20 can slope downward as a radial distance from the central axis 11 increases. In such implementations, an angle between a tangential line to the peripheral region 20 and the central axis 11 can be smaller than an angle between a tangential line to the central region 22 and the central axis 11. Such a geometry can be advantageous in reducing peaks in the distribution of intensity of light emitted from an LED emitter as discussed below. In various implementations, the peripheral region 20 can be partially or completely textured. Partial or complete texturing of the peripheral region 20 can be advantageous in reducing intensity peaks in the distribution of intensity of light at the output of the optical component 10. Partial or complete texturing of the peripheral region 20 can be accomplished by providing a plurality of plurality of microstructures. The plurality of microstructures can include grooves, protrusions, facets, surface or volume holograms, gratings, etc. In various implementations, the plurality of microstructures can be arranged randomly. However, in other implementations, the plurality of microstructures can be arranged to form a regular or an irregular pattern. The plurality of microstructures can have a size between about 1 micron and about 1 mm. In various implementations, the density of the plurality of microstructures can be between 1000/mm2 and 1/mm2. The ranges of the size and density of the microstructures disposed on the surfaces of the peripheral region 20 can be similar to the ranges provided above.
Inner Cavity of the Optical Component
[0065]As discussed above, the inner cavity 13 can be bounded by an inner surface 13a. The inner surface 13a can have a dome shape or a bell shape as viewed along the central axis 11 through the bottom surface. The inner surface 13a can be formed by rotating a curve about the central axis 11. The curve can have any shape. For example, the curve can be concave, convex, aspheric, parabolic or elliptical. Accordingly, in various implementations, a cross-section of the inner surface 13a in a plane including the central axis 11 can be convex, aspheric, parabolic or elliptical. The cross-section of the inner surface 13a in a plane perpendicular to the central axis 11 can be circular or elliptical. In various implementations, an angle between a tangential line to the curve forming the inner surface 13a and the central axis 11 can be small in regions of the inner surface 13a adjacent the bottom surface 19 and large in regions of the inner surface 13a adjacent the top surface 12. For example, the angle between a tangential line to the curve forming the inner surface 13a and the central axis 11 can be between about 0 degrees and about 30 degrees in regions of the inner surface 13a adjacent the bottom surface 19. As another example, the angle between a tangential line to the curve forming the inner surface 13a and the central axis 11 can be between about 60 degrees and about 90 degrees in regions of the inner surface 13a adjacent the top surface 12.
[0066]In various implementations, the inner surface 13a can be partially or completely textured. Partial or complete texturing of the inner surface 13a can be accomplished by providing a plurality of plurality of microstructures. The plurality of microstructures can include grooves, protrusions, facets, surface or volume holograms, gratings, etc. In various implementations, the plurality of microstructures can be arranged randomly. However, in other implementations, the plurality of microstructures can be arranged to form a regular or an irregular pattern. The plurality of microstructures can have a size between about 1 micron and about 1 mm. In various implementations, the density of the plurality of microstructures can be between 1000/mm2 and 1/mm2. The ranges of the size and density of the microstructures disposed on the inner surface 13a can be similar to the ranges provided above. The textured inner surface 13a can advantageously mix the different wavelengths of light emitted from a light source disposed within the inner cavity 13 and reduce color non-uniformity in the near-field and/or far-field radiation pattern emitted from the optical component 10, as discussed in detail below.
Optical Component Coupled to a LED Emitter
[0067]FIG. 2 illustrates a side-view of the optical component 10 disposed over a LED emitter 21. The LED emitter 21 can emit a plurality of wavelengths. For example, the LED emitter 21 can be a WLED and emit wavelengths in the yellow and blue spectral range. The optical component 10 can be disposed over the LED emitter 21 such that the central axis 11 coincides with a central axis of the LED emitter 21. In various implementations, optical component 10 and the LED emitter 21 can be disposed such that the central axis 11 of the optical component 10 and