Abstract:
An illumination system for an aircraft interior has an illumination source. An optical module is coupled to the illumination source. The optical module collects the light emissions from the light source and distributes the collected light over a desired area with a specified intensity profile.

Description:
BACKGROUND 
     Embodiments of this disclosure relate generally to lighting systems, and more particularly, to an interior illumination and lighting system for passenger cabins in airplanes using micro lens array optics. 
     In the past, conventional passenger aircraft illumination systems may have used fluorescent and incandescent light sources. However, light emitting diode (LED) based lighting systems may offer several advantages over such conventional systems. These may include smaller source size, lower electrical power consumption, lower weight, and longer operating lifetimes. Thus, presently, many passenger cabins may use illumination systems based on LEDs. 
     Typical airplane cabin architecture use elongated shapes arranged longitudinally in a manner of continuous strings. It is desirable in the general cabin lighting to have a uniform illumination of the architectural elements. Existing general lighting systems found in the aircraft main cabin may be designed to match architectural features dimensionally in order to achieve a uniform illumination of a desired pattern. Thus existing general lighting applications may make use of continuous linear arrangements of multiple elongated fixtures each of which is based on linear arrays of numerous LEDs. 
     Aircraft interior lighting usually includes dedicated lighting applications such as task and area lighting. These applications generally utilize mostly spot and flood types of lighting fixtures shining on a specific area or isolated target. Another type of lighting applications is feature lighting. These applications often require complex illumination patterns or close match between the light beam shape and illumination target. Both dedicated and feature lighting may use single LED designs as well as arrays of plural LEDs depending on specific function of the fixture. 
     All cabin lighting applications assume certain degree of collection of light radiation from the source and redirection of the light towards the illumination target. 
     Present designs of LED fixtures used in the aircraft interior illumination provide limited control over the spatial distribution of light, which may result in light radiated in undesired directions. Such unwanted light is usually blocked and therefore lost for the purpose of illumination. This loss of light output may need to be compensated by oversizing the lighting system which may lead to increase in weight, cost and energy consumption. Furthermore, the design based on linear LED array may impose certain limitation on the cabin architecture and may increase costs due to the dimensional dependence between a fixture and underlying structural element to which that fixture is attached. 
     Another implication of the limited control over spatial distribution of light may be inadequate illumination pattern such as uneven light level, dark and hot spots, superfluous illumination. This inadequacy may be especially detrimental for the dedicated and feature lighting applications. One prominent example is a passenger reading light that produces excessively wide light cone that may encroach in to other passengers&#39; space. 
     Therefore, it would be desirable to provide a system and method that allows for better utilization of a light output produced by a LED source. 
     SUMMARY 
     An illumination system for an aircraft has an illumination source. An optical module is attached to the illumination source for collection of light emissions from the illumination source and distribution of the collected light emissions over a desired distribution profile. 
     An illumination system for an aircraft has a Light Emitting Diode (LED) module. An electronic module is coupled to the LED module to power and control the LED module. An optical module is coupled to the LED for collection of light emissions from the LED and distribution of the collected light emissions over a desired area. 
     An illumination system for an aircraft has a plurality of light fixtures. Each light fixture has an illumination source. An optical module is coupled to the illumination source for collection of light emissions from the illumination source and distribution of the collected light emissions over a desired area. 
     The features, functions, and advantages may be achieved independently in various embodiments of the disclosure or may be combined in yet other embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein: 
         FIG. 1  is a simplified cross-sectional view showing a compact LED fixture design utilizing a Structured Micro Lens Array (SMLA) in conjunction with collimator; 
         FIG. 2  is a simplified block diagram showing a modular design that divides a lighting fixture in to electronic and optical modules where the LED package is part of the electronic module; 
         FIG. 3  is a simplified block diagram showing a modular design that divides a lighting fixture in to electronic and optical modules where the LED package being a part of the optical module; 
         FIG. 4  is a simplified block diagram showing a modular design that divides a lighting fixture in to light generation and light transformation modules whereas light transformation module includes only SMLA portion of the optical system; 
         FIG. 5  is a simplified block diagram showing a variant of a compact LED fixture design with a redirecting mirror placed between the collimator and SMLA; 
         FIG. 6  is a simplified cross-sectional block diagram showing a LED fixture design utilizing SMLA in conjunction with a optical wave guide (OWG); 
         FIG. 7  is similar to  FIG. 2  wherein an OWG type of fixture is shown; 
         FIG. 8  is similar to  FIG. 3  wherein an OWG type of fixture is shown; 
         FIG. 9A-9B  are diagrams showing general concepts of illumination using a compact LED lighting fixture with SMLA; 
         FIG. 10   a - 10 B is similar to  FIGS. 9A-9B  wherein the wave guide type of LED fixture in shown; 
         FIG. 11  is a diagram showing simplified cross-sectional view of an aircraft passenger cabin with magnified detailed depictions of a typical arrangement of lighting fixtures for general lighting applications; 
         FIG. 12  illustrates one embodiment where a compact LED fixture with micro lens optics is used for cross-bin illumination; 
         FIG. 13  illustrates one embodiment where a wave guide type of LED fixture with micro lens optics is used for ceiling wash lighting; 
         FIG. 14  illustrates one embodiment where a wave guide type of LED fixture with micro lens optics is used for side wall wash lighting; 
         FIG. 15  illustrates one embodiment where compact LED fixtures with micro lens optics are used as personal reading lights; 
         FIG. 16  illustrates one embodiment where a compact LED fixture with micro lens optics is used as a work light shining on a cabinet countertop; 
         FIG. 17  illustrates one embodiment where a compact LED fixture with micro lens optics is used for artwork illumination and; 
         FIG. 18  illustrates one embodiment where a compact LED fixture with micro lens optics is used as a logo light. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , an LED lighting fixture  10  (hereinafter fixture  10 ) may be shown in a simplified cross-section view. The fixture  10  may be comprised of an electronic module  12  and an optical module  11 . The purpose of division of the fixture  10  in to modules  11  and  12  is to separate a stable portion of a design represented by an electronic module  12  from an adaptive portion represented by an optical module  11 . The electronic module  12  may be used to power and control a light source  13 . The light source may be in a form of a high-output LED package  13 . The electronic module  12  may include an LED driver component  17  which may be used to power and control the LED package  13  and a communication component  18  which may be used to send signals to and from the fixture  10 . 
     The optical module  11  may be used to shape a light output  16  in a manner pertinent to a specific application. The optical module  11  may be attached to the electronic module  12  through a standardized mechanical interface. Thus the optical module  11  may be customized to a specific application independently from the electronic module  12 . The optical module  11  may contain one or more lenses. In  FIG. 1 , the optical module  11  may have a collimator  14  and a SMLA component  15 . The collimator  14  may be used to collect the light emissions from the LED package  13  and aligning them in to a beam with little or no divergence. SMLA component  15  is a particular type of micro lens optical device. Some SMLA designs may be capable of homogenizing and redirecting incoming light with minimal losses. At least two categories of SMLA technology may be used in the fixture  10 . One category is represented by Engineered Diffuser™ available from RPC Photonics Inc. Another category is represented by MicroLens™ available from Rambus Inc. The former category may require well collimated light input in order to produce a high quality output. The latter is used in conjunction with an OWG, which is usually a rod, a bar, a plate, or other elongated shape with smooth parallel surfaces made of an optical grade material. Both technologies are capable of homogenizing and shaping the light output with a desired directionality and distribution within broad range of angles. The collimator  14  and the SMLA  15  portions of an optical system may be manufactured as one solid piece. 
     Recent advances in solid state lighting technology brought to the market a number of high-output, yet reliable, and efficient LED components. Such LEDs may be used as a light source for the compact lighting fixture  10  described herein. Some examples of high-output compact LED fixtures for exterior aircraft lighting include those produced by AeroLEDs™, Emteq®, and other manufacturers. 
     The use of a high-output LED package  13  combined with SMLA technology described above may allow for creation of a compact lighting fixture  10  that may fit into a smaller spatial envelope, would be lighter weight, higher efficiency, and simpler design as compared to existing fixtures based on linear arrays of numerous LEDs. Further, SMLA technology may significantly expand capabilities and improve performance of existing designs based of singular LEDs. 
     The LED package  13  may contain a single-die or multi-die LED. Also, three or more single-die LEDs may be combined in one fixture. One singe-die LED fixture may be used for applications where no change or high consistency of color is required. One example of such application may be a personal reading light. Multi-die LED or several LEDs in one fixture may be used to produce a light output with variable color or with stabilized calibrated color. The use of a fixture  10  capable of a variable color light output may allow one to provide mood lighting system for the aircraft cabin. 
     Referring now to  FIG. 2 , fixture  10  is shown with the optical module  11  detached from the electronic module  12 . It may be desirable to have the LED package  13  as a part of the electronic module  12 . Together, LED package  13  and electronic module  12  may make up a light generation module that may produce a raw light output. Optical module  11  may need to be cohesive with a particular type of the LED package  13 . Such cohesion may be essential for standardized interface between an adaptive design of the optical module  11  and a stable design of the electronic module  12 . 
     Referring now to  FIG. 3 , similarly to  FIG. 2 , fixture  10  is shown with the optical module  11 A detached from the electronic module  12 A. It may be desirable to have the LED package  13  as a part of the optical module  11 A. Together LED package  13  and optical module  11 A may make up a complete light source with final output pertinent to a specific application. Electronic module  12 A may need to be cohesive with a particular type of the LED package  13 . Such cohesion may be essential for standardized interface between an adaptive design of the optical module  11 A and a stable design of the electronic module  12 A. 
     Referring now to  FIG. 4 , the adaptive portion of the fixture  10  may be represented by SMLA  15 A alone. This embodiment assumes a modular design that divides fixture  10  in to light generation module  12 B and light transformation module  11 B. Light generation module  12 B may comprise all the electronics including LED package  13  along with collimator  14 A. The module may be able to produce a collimated light beam of a desirable color composition and intensity. Light generation module  12 B generally would have a stable design. The light transformation module  11 B may include SMLA  15 A. The light transformation module  11 B may homogenize and shape the light beam produced by the light generation module  12 B. The light transformation module  11 B may have adaptive design. Both modules  11 B and  12 B may have standardized physical interface with each other. 
     Referring now to  FIG. 5 , in accordance with one embodiment, SMLA  15 A may be spatially separated from the collimator  14 A and placed at an angle to the axis of the collimator  14 A. Resulting fixture  10 A may be suitable for certain configurations that do not provide sufficient room in a lengthwise direction. Such fixture design may include a reflective element  19 . The reflective element  19  may be a mirror or like element. The mirror  19  may be used and positioned to redirect the collimated beam  16 A exiting the collimator  14 A towards the SMLA  15 A that would in turn produce a desired light output as described above. Fixture  10 A can be divided in to functional modules  12  and  11 C similarly to either configuration shown in  FIG. 2 ,  3 , or  4 . 
     Referring now to  FIGS. 6 ,  7 , and  8 , a fixture  10 B is represented. The fixture  10 B may be comprised of an electronic module  12 C and optical module  11 D. Both modules  12 C and  11 B may each have the same basic function as those described for electronic modules  12 - 12 B and optical modules  11 - 11 C above. In the embodiments shown in  FIGS. 6-8 , the optic module  11 D may employ an OWG element  14 B instead of a collimator. The OWG element  14 B may be used to contain the light produced by an LED package  13  and to pass it on to SMLA element  15 B. SMLA  15 B may then create a well-defined light output  16  similarly to the above descriptions. Faces of the OWG  14 B opposite to the LED package  13  and to the SMLA  15 B can be plated by a reflective coating  19 A to alleviate light loss. 
     Analogously to  FIGS. 2 and 3 ,  FIGS. 7 and 8  further illustrate a functional division of the fixture  10 B. In  FIG. 7 , the fixture  10 B is divided in to an electronic module  12 C and optical module  12 D. While in  FIG. 8 , the fixture  10 B is divided into an electronic module  12 D and an optical module  11 E. This modular approach has same purpose and follows same principals as described above. 
     The use of micro lens technology as exemplified by the fixtures  10 - 10 B and its variants may allow creation of virtually unlimited number of illumination patterns with different colors and light intensity profiles. The cabin lighting system comprised of the fixture types described above may be highly efficient in terms of energy consumption, light in weight, and cost efficient in production and operation. The capabilities of contemporary solid state lighting combined with micro lens technologies in the compact design of the fixtures  10 - 10 B and its variants described herein may allow for replacement of existing costly, heavy and bulky linear arrangements. Flexibility of the micro lens technology may allow for greater enhancement of passenger cabin aesthetics and may lead to new lighting applications. Further, the modular implementation of the compact design separating electronics from optics may help to reduce production cost. 
     Referring now to  FIGS. 9A-10B , a general concept of illumination using compact fixture with micro lens optics is shown. The fixture  10  ( FIGS. 9A-9B ) and  10 B ( FIGS. 10A-10B ) produces a well defined light output  16  that may create a pre-determined illumination pattern  20  on a target surface  21 . One can see that geometry of the surface  21  and a position of the lighting fixture  10  ( FIGS. 9A-9B ) and  10 B ( FIGS. 10A-10B ) relative to the surface  21  can be fairly arbitrary and independent of a particular pattern  20  that needs to be created. In other words, micro lens optics may be capable of creating virtually any illumination pattern on any surface from any position of the fixture. 
     Referring now to  FIGS. 11-14 , some general cabin lighting applications are illustrated. At least three embodiments are shown here as follows: ceiling panel surface  21 A may be illuminated by a fixture  10 B producing light output  16 A that may result in ceiling wash lighting depicted as pattern  20 A ( FIG. 11 ); inboard  21 B and outboard  21 C overhead storage surfaces may be illuminated by fixtures  10  or  10 A producing light output  16 B and  16 C respectively that may result in so-called cross-bin lighting depicted by patterns  20 B and  20 C respectively ( FIG. 12-13 ); side wall surface  21 D may be illuminated by the fixture  10 B producing light output  16 D that may result in side wall wash lighting depicted as pattern  20 D ( FIG. 14 ). Use of multiple fixtures positioned a certain distance apart from each other and creating slightly overlapping patterns may create a continuous illumination effect equivalent to that obtained from existing linear fixture arrangements. 
     Referring now to  FIG. 15 , it may be desirable to create a personal reading light producing a spot that covers maximum area without encroaching into adjacent passenger spaces. According to one embodiment of this invention it may be possible to solve this problem with help of the compact fixture described above. The  FIG. 15  shows a typical group of passenger seats each illuminated by a fixture  10  in the capacity of a reading light. Light output  16  from each fixture  10  may be individually shaped to create a rectangular light spot  20  that would not creep beyond a target seat space. It should be noted that a position of the reading light relative to a seat is repetitive from row to row for the most of the aircraft cabin. Thus configuration described herein would require only few variants of SMLA component to cover all possible positions. 
     Referring now to  FIGS. 16 and 17 , at least two embodiments pertaining to dedicated lighting applications are illustrated.  FIG. 16  shows fixture  10  in a capacity of a typical work light shining on a cabinet countertop. This embodiment has the advantage over existing configurations that is a single fixture may uniformly cover the entire work surface without spilling the light over the edges (pattern  20 ) notwithstanding shape and orientation of the surface. Artwork illumination is another application where coherence between target form and the lighting pattern may be desirable. Existing fixtures may utilize multiple LED arrangements alongside complicated optics and apertures to achieve such coherence.  FIG. 17  shows fixture  10  highlighting a painting on the wall. This embodiment leverages micro lens technology to achieve a pattern  20  that closely matches the shape of an artwork piece  21  using a single LED source in a compact fixture design. 
     Referring now to  FIG. 18 , plurality of the feature lighting applications can be found in today&#39;s premium cabin architectures. Feature lighting may be characterized by complex lighting schemes. Some may include and even combine wash lights, accent lights, logo lights, and other types of decorative illumination. Such variety and complexity may involve complicated fixture arrangements that often require expensive point design. Micro lens technology may be used to create much more simple and repeatable fixture design as one described above that can satisfy most if not all diverse requirements of the feature lighting. Prior art describes certain types of SMLA that are capable of creating not only an arbitrary continuous shape but also a shape with voids (or intentionally dark spots) within a main shape as well as a group of separate shapes.  FIG. 18  illustrates one embodiment where fixture  10  is used to form a light pattern  20  with appearance of a logo image composed of several letter-like forms. 
     While embodiments of the disclosure have been described in terms of various specific embodiments, those skilled in the art will recognize that the embodiments of the disclosure may be practiced with modifications within the spirit and scope of the claims.