Patent Publication Number: US-2011063846-A1

Title: Extended source light module

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     Pursuant to 35 U.S.C. §119(e), this application claims the benefit of U.S. Provisional Application Ser. No. 61/242,221 filed on Sep. 14, 2009, the contents of which are hereby incorporated by reference herein in their entirety. 
    
    
     BACKGROUND 
     1. Field 
     The present disclosure relates to an extended source light module. 
     2. Description of Related Art 
     LEDs have been developed for many years and have been widely used in various light applications. As LEDs are light-weight, consume less energy, and have a good electrical power to light conversion efficacy, they have been used to replace conventional light sources, such as incandescent lamps and fluorescent light sources. LEDs may be utilized in an array. An extended light source includes an LED array. Light from an extended light source is distributed by a reflector. However, there is a need in the art to improve the light distribution from an extended light source and to provide a predetermined light distribution as a function of the properties of the extended light source. 
     SUMMARY 
     In one aspect of the disclosure, a light source includes an extended light source, a first optical element, and a second optical element. The first optical element is coupled to the extended light source. The second optical element is coupled to the first optical element. The second optical element has a central reflective member and a refractive member surrounding the central reflective member. 
     In one aspect of the disclosure, an apparatus configured to provide a predetermined light distribution includes a solid state light source, a first optical element, and a second optical element. The first optical element is coupled to the solid state light source. The first optical element has a first optical element input aperture, a first optical element output aperture, and side walls approximately symmetric with respect to a first optical axis. The solid state light source is located in the first optical element input aperture in a plane perpendicular to the first optical axis. The first optical element output aperture is configured to provide transformed light and untransformed light in a first predetermined light distribution. The transformed light is light reflected off the side walls. The untransformed light is light unreflected off the side walls. The side walls have a curvature to provide the transformed light at the first optical element output aperture such that the transformed light in superposition with the untransformed light has the first predetermined light distribution at the first optical element output aperture. The second optical element is coupled to the first optical element. The second optical element is located parallel to the plane. The second optical element has a secondary optical axis coaxial to the first optical axis. The second optical element has a second optical element input and a second optical element output. The second optical element output provides a second predetermined light distribution. The second optical element input has a reflective member located around the secondary optical axis and a refractive member located around the reflective member. The reflective member has a profile configured with respect to the first predetermined light distribution to reflect light towards the refractive member. The refractive member has a plurality of prismatic facets. Each of the prismatic facets has an individual inclination angle relative to the plane. Each individual inclination angle is configured as a function of an intensity of the transformed light, an intensity of light incident the reflective member, and an intensity of the untransformed light to produce the second predetermined light distribution with a predetermined light pattern. Light emitted by the solid state light source is transformed by the first optical element, the reflective member of the second optical element, and the refractive member of the second optical element to produce the second predetermined light distribution with the predetermined light pattern. The second predetermined light distribution is the predetermined light distribution. 
     In an aspect of the disclosure, a light emitting apparatus includes a solid state light source, a first optical element, and a second optical element. The first and second optical elements are configured to direct light emitted from the solid state light source to the second optical element. The second optical element includes a first member and a second member. The first member is configured to reflect at least a portion of the light to the second member. The second member is configured to refract at least a portion of the reflected light. 
     In an aspect of the disclosure, a light emitting apparatus includes a first optical element, a second optical element having a first member and a second member, and a solid state light source. The solid state light source is arranged with the first and second optical elements such that light emitted from the light source is directed by the first optical element to the second optical element where at least a portion of the light is reflected by the first member towards the second member and at least a portion of the reflected light is refracted by the second member. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a conceptual cross-sectional side view illustrating an example of an LED. 
         FIG. 2  is a conceptual top view illustrating an example of a light emitting element. 
         FIG. 3A  is a conceptual top view illustrating an example of a white light emitting element. 
         FIG. 3B  is a conceptual cross-sectional side view of the white light emitting element in  FIG. 3A . 
         FIG. 4  is a side view of an extended source light module. 
         FIG. 5  is a bottom view of the secondary optical element. 
         FIG. 6A  is a perspective exploded view of an LED array module. 
         FIG. 6B  is a perspective of the LED array module of  FIG. 6A . 
         FIG. 7  is a view of a heat sink. 
         FIG. 8  is a conceptual view illustrating a configuration for providing a predetermined light distribution. 
     
    
    
     DETAILED DESCRIPTION 
     Various aspects of the present invention will be described herein with reference to drawings that are schematic illustrations of idealized configurations of the present invention. As such, variations from the shapes of the illustrations as a result, for example, manufacturing techniques and/or tolerances, are to be expected. Thus, the various aspects of the present invention presented throughout this disclosure should not be construed as limited to the particular shapes of elements (e.g., regions, layers, sections, substrates, etc.) illustrated and described herein but are to include deviations in shapes that result, for example, from manufacturing. By way of example, an element illustrated or described as a rectangle may have rounded or curved features and/or a gradient concentration at its edges rather than a discrete change from one element to another. Thus, the elements illustrated in the drawings are schematic in nature and their shapes are not intended to illustrate the precise shape of an element and are not intended to limit the scope of the present invention. 
     It will be understood that when an element such as a region, layer, section, substrate, or the like, is referred to as being “on” another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present. It will be further understood that when an element is referred to as being “formed” on another element, it can be grown, deposited, etched, attached, connected, coupled, or otherwise prepared or fabricated on the other element or an intervening element. In addition, when a first element is “coupled” to a second element, the first element may be directly connected to the second element or the first element may be indirectly connected to the second element with intervening elements between the first and second elements. 
     Furthermore, relative terms, such as “lower” or “bottom” and “upper” or “top,” may be used herein to describe one element&#39;s relationship to another element as illustrated in the drawings. It will be understood that relative terms are intended to encompass different orientations of an apparatus in addition to the orientation depicted in the drawings. By way of example, if an apparatus in the drawings is turned over, elements described as being on the “lower” side of other elements would then be oriented on the “upper” side of the other elements. The term “lower” can therefore encompass both an orientation of “lower” and “upper,” depending of the particular orientation of the apparatus. Similarly, if an apparatus in the drawing is turned over, elements described as “below” or “beneath” other elements would then be oriented “above” the other elements. The terms “below” or “beneath” can therefore encompass both an orientation of above and below. 
     Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and this disclosure. 
     As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprise,” “comprises,” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The term “and/or” includes any and all combinations of one or more of the associated listed items. 
     Various aspects of an LED array module may be illustrated with reference to one or more exemplary configurations. As used herein, the term “exemplary” means “serving as an example, instance, or illustration,” and should not necessarily be construed as preferred or advantageous over other configurations of an LED array module disclosed herein. 
     Furthermore, various descriptive terms used herein, such as “on” and “transparent,” should be given the broadest meaning possible within the context of the present disclosure. For example, when a layer is said to be “on” another layer, it should be understood that that one layer may be deposited, etched, attached, or otherwise prepared or fabricated directly or indirectly above or below that other layer. In addition, something that is described as being “transparent” should be understood as having a property allowing no significant obstruction or absorption of electromagnetic radiation in the particular wavelength (or wavelengths) of interest, unless a particular transmittance is provided. 
     A solid state component is a device built entirely from solid materials in which the electrons are entirely confined within the solid material. The solid state component may be a light source. The light source may be constructed from an array of light emitting semiconductor cells. One example of a light emitting semiconductor cell is an LED. The LED is well known in the art, and therefore, will only briefly be discussed to provide a complete description of the invention. 
       FIG. 1  is a conceptual cross-sectional side view illustrating an example of an LED. An LED is a semiconductor material impregnated, or doped, with impurities. These impurities add “electrons” and “holes” to the semiconductor, which can move in the material relatively freely. Depending on the kind of impurity, a doped region of the semiconductor can have predominantly electrons or holes. A doped region with electrons may be referred to as an n-type semiconductor region. A doped region with holes may be referred to as a p-type semiconductor region. In LED applications, the semiconductor includes an n-type semiconductor region, a p-type semiconductor region, and an intervening active region between the n-type and p-type semiconductor regions. When a forward voltage sufficient to overcome the reverse electric field is applied across the p-n junction, electrons and holes are forced into the active region and combine. When electrons combine with holes, they fall to lower energy levels and release energy in the form of light. 
     Referring to  FIG. 1 , the LED  101  includes a substrate  102 , an epitaxial-layer structure  104  on the substrate  102 , and a pair of electrodes  106  and  108  on the epitaxial-layer structure  104 . The epitaxial-layer structure  104  comprises an active region  116  sandwiched between two oppositely doped epitaxial regions. In this example, an n-type semiconductor region  114  is formed on the substrate  102  and a p-type semiconductor region  118  is formed on the active region  116 , however, the regions may be reversed. That is, the p-type semiconductor region  118  may be formed on the substrate  102  and the n-type semiconductor region  114  may formed on the active region  116 . As those skilled in the art will readily appreciate, the various concepts described throughout this disclosure may be extended to any suitable epitaxial-layer structure. Additional layers (not shown) may also be included in the epitaxial-layer structure  104 , including but not limited to buffer, nucleation, contact and current spreading layers as well as light extraction layers. 
     The electrodes  106  and  108  may be formed on the surface of the epitaxial-layer structure  104 . The p-type semiconductor region  118  is exposed at the top surface, and therefore, the p-type electrode  106  may be readily formed thereon. However, the n-type semiconductor region  114  is buried beneath the p-type semiconductor region  118  and the active region  116 . Accordingly, to form the n-type electrode  108  on the n-type semiconductor region  114 , a portion of the active region  116  and the p-type semiconductor region  118  is removed to expose the n-type semiconductor region  114  therebeneath. After this portion of the epitaxial-layer structure  104  is removed, the n-type electrode  108  may be formed. 
     As discussed above, one or more light emitting cells may be used to construct a light emitting element. A light emitting element may be constructed in a 2-dimensional planar fashion. One example of a light emitting element will now be presented with reference to  FIG. 2 .  FIG. 2  is a conceptual top view illustrating an example of a light emitting element. In this example, a light emitting element  200  is configured with multiple LEDs  201  arranged on a substrate  202 . The substrate  202  may be made from any suitable material that provides mechanical support to the LEDs  201 . Preferably, the material is thermally conductive to dissipate heat away from the LEDs  201 . The substrate  202  may include a dielectric layer (not shown) to provide electrical insulation between the LEDs  201 . The LEDs  201  may be electrically coupled in parallel and/or series by a conductive circuit layer, wire bonding, or a combination of these or other methods on the dielectric layer. 
     The light emitting element may be configured to produce white light. White light may enable the light emitting element to act as a direct replacement for conventional light sources used today in incandescent, halogen and fluorescent lamps. There are at least two common ways of producing white light. One way is to use individual LEDs that emit wavelengths (such as red, green, blue, amber, or other colors) and then mix all the colors to produce white light. The other way is to use a phosphor material or materials to convert monochromatic light emitted from a blue or ultra-violet (UV) LED to broad-spectrum white light. The present invention, however, may be practiced with other LED and phosphor combinations to produce different color lights. 
     An example of a white light emitting element will now be presented with reference to  FIGS. 3A and 3B .  FIG. 3A  is a conceptual top view illustrating an example of a white light emitting element and  FIG. 3B  is a conceptual cross-sectional side view of the white light emitting element in  FIG. 3A . The white light emitting element  300  is shown with a substrate  302  which may be used to support multiple LEDs  301 . The substrate  302  may be configured in a manner similar to that described in connection with  FIG. 2  or in some other suitable way. A phosphor material  308  may be deposited within a cavity defined by an annular, or other shape, or other boundary  310  that extends circumferentially, or in any shape, around the upper surface of the substrate  302 . The annular boundary  310  may be formed with a suitable mold, or alternatively, formed separately from the substrate  302  and attached to the substrate  302  using an adhesive or other suitable means. The phosphor material  308  may include, by way of example, phosphor particles suspended in an epoxy, silicone, or other carrier or may be constructed from a soluble phosphor that is dissolved in the carrier. 
     In an alternative configuration of a white light emitting element, each LED may have its own phosphor layer. As those skilled in the art will readily appreciate, various configurations of LEDs and other light emitting cells may be used to create a white light emitting element. Moreover, as noted earlier, the present invention is not limited to solid state lighting devices that produce white light, but may be extended to solid state lighting devices that produce other colors of light. 
       FIG. 4  is a side view of an extended source light module  400 . The module  400  includes an extended light source  402 , which may be a multi-chip LED array. The extended light source  402  is coupled to a primary optical element  404 . The primary optical element  404  has a primary optical element input aperture  406  and a primary optical element output aperture  408 . The primary optical element  404  further includes a primary optical element side wall  410  that is conically shaped to distribute light emitted from the extended light source  402 . A secondary optical element  412  is coupled to the primary optical element  404 . The secondary optical element  412  includes a secondary optical element first member  414  and a secondary optical element second member  416 . The secondary optical element first member  414  has a reflective surface  420  and the secondary optical element second member  416  has prismatic facets  418  to refract light. The secondary optical element first member  414  has a conical lower surface  422  that is reflective in order to reflect light from the extended light source  402  into the prismatic facets  418 . In one configuration, the secondary optical element  412  is one component, with the first member  414  and the second member  416  formed with different properties in order to reflect and to refract light, respectively. In another configuration, the secondary optical element  412  is two separate components, with the first member  414  and the second member  416  being separate components coupled together. 
     The module  400  provides a predetermined light distribution from the extended light source  402 . As discussed supra, the module  400  includes an extended light source  402 , a primary optical element  404 , and a secondary optical element  412 . The extended light source  402  has a predetermined spatial light distribution. The primary optical element  404  collects, redirects, and redistributes portions of the light emitted from the extended light source  402 . The extended light source  402  is located in the input aperture  406  in a plane perpendicular to an optical axis of the primary optical element  404 . The primary optical element  404  creates in superposition with an untransformed portion of the emitted light a precalculated intensity distribution across the output aperture  408  through a calculation of a profile of the side wall  410 , located between the input aperture  406  and the output aperture  408 , as a function of a given specific extended light source  402 . 
     The secondary optical element  412  is located in a plane of the output aperture  408  of the primary optical element  404  with an optical axis coaxial to the optical axis of the primary optical element  404 . The secondary optical element  412  has a lower surface and an upper surface. The lower surface receives light and the upper surface emits the received light. The secondary optical element  412  creates a predetermined light pattern. The secondary optical element  412  includes a first member  414  and a second member  416 . The first member  414  is located around the optical axis of the secondary optical element  404 . The first member  414  has a reflective surface with a profile calculated as a function of the intensity distribution across the output aperture  408 . The first member  414  redistributes and redirects light received from the primary optical element  404  towards the second member  416 , which is disposed around the first member  414 . The second member  416  includes a number of prismatic facets  418 . Each of the prismatic facets  418  has an individual inclination angle relative to a reference plane disposed perpendicular to the optical axis. The individual inclination angle for each of the prismatic facets is calculated as a function of the actual intensity of the direct incident light from the primary optical element  404 , an intensity of light reflected from the first member  414 , and the desired intensity of the outgoing light in a preselected/predetermined direction. 
     Accordingly, the module  400  provides a triple transformation of light, with the primary optical element providing a first transformation as a function of the curvature of the side wall  410  and the size of the input aperture  406  and the output aperture  408 , the secondary optical element first member  414  providing a second transformation as a function of its size and the curvature of its reflective lower surface  422 , and the secondary optical element second member  416  providing a third transformation as a function of the individual inclination angle of its prismatic facets  418 . The triple transformation of the module  400  produces a predetermined light envelope and creates a predetermined light pattern. 
     The extended light source  402  may be a multi-chip LED array. The module  400  may include a phosphor layer on the extended light source  402  or a remote phosphor located remote from the extended light source  402 . The secondary optical element  412  may be rotationally symmetrical around the optical axis and the prismatic facets  418  may be in circular relation. Alternatively, the secondary optical element  412  may be asymmetrical around the optical axis and the prismatic facets  418  may be in non-circular relation. The outer surface of the secondary optical element second member  416  may be shaped to be rotationally symmetric around the optical axis. Alternatively, the outer surface of the secondary optical element second member  416  may have an arbitrary shape with a shape asymmetric with respect to the optical axis. 
     The secondary optical element  412  may be a light shaping element and therefore may shape the light that passes through the secondary optical element  412 . A simple glass cover is an example of an element that is not a light shaping element. The secondary optical element  412  may be a non-Lambertian diffuser, and therefore the radiant intensity of the light is not directly proportional to the cosine of the angle between an observer&#39;s line of sight and the normal to the surface. As such, when the secondary optical element  412  is a non-Lambertian diffuser, the light from the secondary optical element  412  does not appear to have the same radiance from different observer angles. 
       FIG. 5  is a bottom view of the secondary optical element  412 . The secondary optical element  412  has a central portion, referred to as the first member  414 , around point  415  that reflects light. Point  415  is the bottom point of the conically shaped portion of the first member  414 . An outer portion, outside of the central portion, referred to as the second member  416 , has a plurality of facets  418  that refract light. 
       FIG. 6A  is a perspective exploded view of an LED array module  600 .  FIG. 6B  is a perspective view of the LED array module  600 . As shown in  FIG. 6A , the LED array module  600  includes a printed circuit board  602 , a frame  604  attachable to the printed circuit board  602 , an LED array  402  attachable to the frame  604 , a reflector  404  for transforming light from the LED array  402 , a cover  612  for covering the LED array  402  and the reflector  404 , and a secondary optic  412  for further transforming the light emitted from the LED array  402 . The LED array  402  may be the light emitting element  200  or the light emitting element  300 . The LED array  402  is sealed within the cover  612  with the silicone o-ring  622  and the rubber grommet  624  that is insertable into a hole in the side of the cover  612 . 
       FIG. 7  is a view of a heat sink  700 . The heat sink  700  may be aluminum or an aluminum alloy. The heat sink  700  has a plurality of arms  720  that extend from a core  722 . The heat sink  700  further includes holes for allowing the module  600  to attach. As shown in  FIG. 7 , the heat sink  700  is the base of the assembly. However, the heat sink may also be configured to serve as the assembly enclosure. 
       FIG. 8  is a conceptual view illustrating a configuration for providing a predetermined light distribution. The apparatus  800  includes a solid state component  402  (e.g., LED array), a primary optical element  404 , and a secondary optical element  412 . The primary optical element  404  is coupled to the solid state component  402 . The primary optical element  404  has a primary optical element input aperture  404 I, a primary optical element output aperture  404 O, and side walls  410  approximately symmetric with respect to a primary optical axis  820 . The solid state component  402  is located in the primary optical element input aperture  404 I in a plane perpendicular to the primary optical axis  820 . The primary optical element output aperture  404 O is configured to provide transformed light  804  and untransformed light  802  in a primary predetermined light distribution  802 / 804 . The transformed light  804  is light reflected off the side walls  410 . The untransformed light  802  is light unreflected off the side walls. The side walls  410  have a curvature to provide the transformed light  804  at the primary optical element output aperture  404 O such that the transformed light  804  in superposition with the untransformed light  802  has the primary predetermined light distribution  802 / 804  at the primary optical element output aperture  404 O. 
     The secondary optical element  412  is coupled to the primary optical element  404 . The secondary optical element is located parallel to the plane of the primary optical element input aperture  404 I. The secondary optical element  412  has a secondary optical axis  820  coaxial to the primary optical axis  820  (i.e., the axes are the same). The secondary optical element  412  has a secondary optical element input  412 I and a secondary optical element output  412 O. The secondary optical element output  412 O provides the predetermined light distribution  808 . The secondary optical element input  404 I has a reflective member  414  located around the secondary optical axis  820  and a refractive member  416  located around the reflective member  414 . The reflective member  414  has a profile (e.g., approximately conically shaped) configured with respect to the primary predetermined light distribution  802 / 804  to reflect light  806  towards the refractive member  416 . The refractive member  416  has a plurality of prismatic facets  418 . Each of the prismatic facets  418  has an individual inclination angle relative to the plane of the primary optical element input aperture  404 I. Each individual inclination angle is configured as a function of an intensity of the transformed light  804 , an intensity of light  806  incident the reflective member  414 , an intensity of the untransformed light  802 , and an intensity of light exiting the secondary optical element output  808 . 
     The light  810  emitted by the solid state component  402  is transformed by the primary optical element  404 , the reflective member  414 , and the refractive member  416  of the secondary optical element  412  to produce the predetermined light distribution with a predetermined light pattern  808 . 
     The various aspects of this disclosure are provided to enable one of ordinary skill in the art to practice the present invention. Modifications to various aspects of an LED array module presented throughout this disclosure will be readily apparent to those skilled in the art, and the concepts disclosed herein may be extended to other applications. Thus, the claims are not intended to be limited to the various aspects of an LED array module presented throughout this disclosure, but are to be accorded the full scope consistent with the language of the claims. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed under the provisions of 35 U.S.C. §112, sixth paragraph, unless the element is expressly recited using the phrase “means for” or, in the case of a method claim, the element is recited using the phrase “step for.”