Patent Publication Number: US-10791386-B2

Title: Method of manufacturing a composite panel

Description:
CROSS REFERENCE TO RELATED PATENT APPLICATION 
     The present disclosure claims priority to and is a divisional of U.S. patent application Ser. No. 14/994,863, filed on Jan. 13, 2016, now U.S. Pat. No. 10,091,567, which is a continuation-in-part of U.S. patent application Ser. No. 14/940,241, filed on Nov. 13, 2015, now U.S. Pat. No. 10,118,547, the entire contents of each of which are herein incorporated by reference. 
    
    
     FIELD 
     The present disclosure generally relates to interior lighting panels for passenger aircraft, and more particularly, to aircraft ceiling, stow bin, valences, sidewalls or other mounted lighting panels adapted to display a starry nighttime sky effect. The present disclosure also relates to composite panels including printed microphones or loud-speakers, and more particularly, to interior panels for passenger vehicles (e.g., aircraft) or to other walls within conference rooms for panels adapted to integrate a printed sheet of microphones and loud-speakers, and/or light sources, and further to other structures such as a table or a phone case/cover to integrate the printed sheet. 
     BACKGROUND 
     Passenger aircraft that operate over long distances during the night typically include interior lighting arrangements that provide substantially reduced ambient light so that passengers can sleep comfortably, but which is still bright enough to enable those passengers who choose not to sleep to move about the cabin safely. For example, some models of passenger jets incorporate ceiling panels that incorporate light emitting diodes (LEDs) arranged so as to blink in random patterns against a gray or dark blue background, and which, in a reduced ambient light condition, gives the relaxing, soporific appearance of a starry nighttime sky, and hence, is referred to as a “Starry Sky” ceiling lighting arrangement. 
     A conventional Starry Sky lighting panel may include complex discrete wiring and electrical components located on a back surface thereof. The panel may use lenses, lens holders, hardwired LEDs, and wire bundles deployed on individual standoffs, and discrete power conditioning and control components that are integrated in a relatively complicated manufacturing process to produce a panel that gives the desired effect. In a typical installation, the aircraft may contain many of such panels, each of which may contain many LEDs. A typical Starry Skies ceiling panel feature requires the LEDs to be manually installed in the panel. 
     In addition, typically microphones and speakers are also installed in a ceiling panel of aircraft to enable communication with passengers. 
     The disadvantages and limitations of these solutions are that the method of producing the panel is costly and relatively heavy, requires intensive, ergonomically costly manual labor steps due to the amount of manually installed wire, takes up a relatively large volume behind the ceiling panels and is difficult to retrofit into existing aircraft. Because of the mass and volume of the wires for this system, it is typically limited to only be installed in ceilings. 
     In light of the foregoing, there is a need in the relevant industry for an aircraft ceiling lighting panel that provides a Starry Sky effect through a “solid state” method that does not use lenses, lens holders, wired LEDs and complex associated point-to-point wiring, reduces panel weight, volume, manual fabrication and assembly labor and cost, eliminates repetitive injuries, and which can easily be retrofitted into existing aircraft. 
     There is also a need in the relevant industry for an ability to seamlessly integrate microphones and/or loud-speakers into panels that avoids complex associated point-to-point wiring, reduces panel weight, volume, and manual fabrication and assembly labor and cost. 
     SUMMARY 
     In one example, a lighting panel is described comprising a substrate having a planar surface, a plurality of electrically conductive traces printed onto the planar surface of the substrate, and a plurality of light sources mounted onto the plurality of electrically conductive traces on the planar surface of the substrate at mounting positions such that the plurality of electrically conductive traces form an electrical interconnection between selected ones of the plurality of electrically conductive traces and associated ones of the plurality of light sources. The lighting panel includes a polymer sheet provided over the plurality of light sources, and a composite base upon which a stack-up of the substrate with the printed plurality of electrically conductive traces, the plurality of light sources mounted on the planar surface, and the polymer sheet is applied. The plurality of light sources are embedded into the composite base and are also flush with a top surface of the stack-up, and the substrate is also embedded into the composite base underneath the plurality of light sources at the mounting positions. 
     In another example, a method of manufacturing a lighting panel is described. The method comprises printing a plurality of electrically conductive traces onto a planar surface of a substrate, mounting a plurality of light sources onto the plurality of electrically conductive traces on the planar surface of the substrate at mounting positions such that the plurality of electrically conductive traces form an electrical interconnection between selected ones of the plurality of electrically conductive traces and associated ones of the plurality of light sources, providing a polymer sheet over the plurality of light sources, and providing a stack-up of the substrate with the printed plurality of electrically conductive traces, the plurality of light sources mounted on the planar surface, and the polymer sheet onto a composite base. The method also includes applying pressure and heat to the stack-up and the composite base to embed the plurality of light sources into the composite base so as to be flush with a top surface of the stack-up, and to embed the substrate into the composite base underneath the plurality of light sources at the mounting positions. 
     In another example, a composite panel is described that comprises a plurality of plies assembled in a stack-up, and a trace sheet with electrically conductive traces and a plurality of transducer discs positioned onto the electrically conductive traces at positions such that the electrically conductive traces form an electrical interconnection between selected ones of the electrically conductive traces and associated ones of the transducer discs. The trace sheet is included as an internal ply in the stack-up of the plurality of plies. The composite panel also comprises a composite base upon which the stack-up of the plurality of plies is applied, and the plurality of plies are cured upon the composite base to integrate the trace sheet and the plurality of transducer discs into the composite base. 
     Within examples, the transducer discs may include microphone discs or loud-speaker discs. In one example, the transducer discs may include acoustic-to-electric transducers that convert sound into an electrical signal as a microphone. In another example, the transducer discs include electroacoustic transducers that convert an electrical audio signal into a corresponding sound as a loud-speaker. And, in yet another example, some of the transducer discs may include acoustic-to-electric transducer discs as microphones and some of the transducer discs may include electroacoustic transducers as loud-speakers. 
     In another example, a method of manufacturing a composite panel is described that comprises printing electrically conductive traces onto a planar surface of a trace sheet, positioning a plurality of transducer discs onto the electrically conductive traces at positions such that the electrically conductive traces form an electrical interconnection between selected ones of the electrically conductive traces and associated ones of the transducer discs, and positioning a stack-up of a plurality of plies onto a composite base. The plurality of plies includes the trace sheet with the printed electrically conductive traces and the plurality of transducer discs, and the trace sheet is included as an internal ply in the stack-up of the plurality of plies. The method also includes applying pressure and heat to the stack-up and the composite base to cure the plurality of plies upon the composite base and to integrate the trace sheet and the plurality of transducer discs into the composite base. 
     The features, functions, and advantages that have been discussed can be achieved independently in various embodiments or may be combined in yet other embodiments further details of which can be seen with reference to the following description and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The novel features believed characteristic of the illustrative embodiments are set forth in the appended claims. The illustrative embodiments, however, as well as a preferred mode of use, further objectives and descriptions thereof, will best be understood by reference to the following detailed description of an illustrative embodiment of the present disclosure when read in conjunction with the accompanying drawings, wherein: 
         FIG. 1  illustrates a portion of an example process for manufacturing a lighting panel, in which a substrate is shown that has a planar surface, according to an example embodiment. 
         FIG. 2  illustrates another portion of the example process for manufacturing a lighting panel, in which a plurality of light sources are mounted onto the plurality of electrically conductive traces on the planar surface of the substrate at mounting positions, according to an example embodiment. 
         FIG. 3  illustrates another portion of the example process for manufacturing a lighting panel, in which a polymer sheet is provided over the light sources, according to an example embodiment. 
         FIG. 4  illustrates another portion of the example process for manufacturing a lighting panel, in which a composite base is provided upon which a stack-up of the substrate with the printed plurality of electrically conductive traces, the light sources mounted on the planar surface, and the polymer sheet is applied, according to an example embodiment. 
         FIG. 5  illustrates another portion of the example process for manufacturing a lighting panel, in which the light sources are embedded into the composite base and are also flush with a top surface of the stack-up, and the substrate is also embedded into the composite base underneath the light sources at the mounting positions, according to an example embodiment. 
         FIG. 6  illustrates another portion of the example process for manufacturing a lighting panel, in which a decorative film can also be applied over the polymer sheet to cover the light sources, according to an example embodiment. 
         FIG. 7  illustrates a top view of the substrate with electrically conductive traces, according to an example embodiment. 
         FIG. 8  illustrates the substrate with a circuit including light sources, according to an example embodiment. 
         FIG. 9  shows a flowchart of an example method for manufacturing a lighting panel, according to an example embodiment. 
         FIG. 10  illustrates a portion of an example process for manufacturing a composite panel, in which a trace sheet is shown that has a planar surface, according to an example embodiment. 
         FIG. 11  illustrates another portion of an example process for manufacturing a composite panel, in which a plurality of plies are assembled in a stack-up, according to an example embodiment. 
         FIG. 12  illustrates another portion of an example process for manufacturing a composite panel, in which the stack-up of the plurality of plies is applied to a composite base, according to an example embodiment. 
         FIG. 13  illustrates another portion of an example process for manufacturing a composite panel, in which the trace sheet and the plurality of transducer discs are integrated into the composite base, according to an example embodiment. 
         FIG. 14  illustrates an example completed composite panel. 
         FIG. 15  illustrates a side view of one example of the trace sheet, according to an example embodiment. 
         FIG. 16  illustrates a detailed side view of one of the transducer discs, such as the transducer disc, according to an example embodiment. 
         FIG. 17  illustrates a side view of another example of the trace sheet, according to an example embodiment. 
         FIG. 18  illustrates a side view of yet another example of the trace sheet, according to an example embodiment. 
         FIG. 19  illustrates a side view of yet another example of the trace sheet, according to an example embodiment. 
         FIG. 20  shows a flowchart of an example method for manufacturing a composite panel, according to an example embodiment. 
         FIG. 21  shows a flowchart of another example method for manufacturing a composite panel, according to an example embodiment. 
         FIG. 22  shows a flowchart of yet another example method for manufacturing a composite panel, according to an example embodiment. 
         FIG. 23  shows a flowchart of yet another example method for manufacturing a composite panel, according to an example embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Disclosed embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all of the disclosed embodiments are shown. Indeed, several different embodiments may be described and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are described so that this disclosure will be thorough and complete and will fully convey the scope of the disclosure to those skilled in the art. 
     Within examples, a lighting panel and a method of manufacturing a lighting panel are described. The lighting panel comprises a substrate having a planar surface, a plurality of electrically conductive traces printed onto the planar surface of the substrate, and a plurality of light sources mounted onto the plurality of electrically conductive traces on the planar surface of the substrate at mounting positions such that the plurality of electrically conductive traces form an electrical interconnection between selected ones of the plurality of electrically conductive traces and associated ones of the plurality of light sources. A polymer sheet can be provided over the plurality of light sources. A composite base is provided upon which a stack-up of the substrate with the printed plurality of electrically conductive traces, the plurality of light sources mounted on the planar surface, and the polymer sheet is applied. The plurality of light sources are embedded into the composite base and are also flush with a top surface of the stack-up, and the substrate is also embedded into the composite base underneath the plurality of light sources at the mounting positions. 
     Example lighting panels described integrate light sources into crush core panels to create a lighting effect that may be used for interior panels of aircraft, for example. Example methods for manufacturing described herein may use a plastic film with printed traces and bonded light sources that are then integrated into a panel via a method of crush core processing with composites. A decorative layer can then be applied over the light sources. This process can be used to integrate a lighting feature similar to Starry Skies into any crush core aircraft panels (e.g., ceilings, stow bins, valences, sidewalls, etc.). 
     Thus, in some examples, the disclosure relates to “Starry Sky” aircraft ceiling panel lighting systems and methods for manufacturing them. The lighting panels comprise a plurality of small light sources, such as micro-miniature light emitting diodes (LEDs), or alternatively, organic light emitting diodes (OLEDs), and together with control circuitry connected with conductive traces that are printed or otherwise formed onto an aircraft structural ceiling panel and/or to a lamination of flexible substrates that are then bonded to such a structural ceiling panel in the form of an appliqué therefor. The result is a Starry Sky lighting panel construction that is lighter, smaller, less expensive, and easier to retrofit to existing aircraft than existing Starry Sky lighting panel systems. 
     In other examples, a composite panel and method of manufacturing a composite panel is described. An example composite panel includes a plurality of plies assembled in a stack-up, and a trace sheet with electrically conductive traces and a plurality of transducer discs positioned onto the electrically conductive traces at positions such that the electrically conductive traces form an electrical interconnection between selected ones of the electrically conductive traces and associated ones of the transducer discs. The trace sheet is included as an internal ply in the stack-up of the plurality of plies. The composite panel also includes a composite base upon which the stack-up of the plurality of plies is applied, and the plurality of plies are cured upon the composite base to integrate the trace sheet and the plurality of transducer discs into the composite base. In examples described below, the transducer discs may be microphone discs or loud-speaker discs. In further examples, the composite panel may also include light sources, like the lighting panel above, in combination with microphone discs and/or loud-speaker discs. Any combination of microphone discs, loud-speaker discs, and light sources may be included in the composite panel. 
     Referring now to  FIGS. 1-6 , an example process is shown for manufacturing a lighting panel, according to an example embodiment. In  FIG. 1 , a substrate  200  is shown that has a planar surface  202 . The planar surface  202  provides a relatively smooth surface or substantially flat surface. 
     As used herein, by the term “substantially” it is meant that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to skill in the art, may occur in amounts that do not preclude the effect the characteristic was intended to provide. Similarly, the term “about” includes aspects of the recited characteristic, parameter, or value allowing for deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to skill in the art, and also ranges of the parameters extending a reasonable amount to provide for such variations. 
     The substrate  200  may comprise a polymer film, or a polyvinyl fluoride (PVF) material, such as Tedlar film (Du Pont Tedlar polyvinyl fluoride (PVF)), for example. Other flexible, dielectric substrate materials may also be used for the substrate  200 , such as, for example, Kapton, Mylar or polyvinyl chloride (PVC) materials. 
     A plurality of electrically conductive traces  204  are printed onto the planar surface  202  of the substrate  200 . Electrically conductive traces  204  are shown in  FIG. 7 . The electrically conductive traces  204  can be written on the planar surface  202  of the substrate  200  so as to make electrical connections with respective leads of electrical components (i.e., anode and cathode of LEDs). 
     One or more of several conductive trace writing methods may be used to print the electrically conductive traces  204  on the substrate  200 . In one example, plasma spraying may be used to deposit a wide range of conductive or non-conductive materials directly onto conformal surfaces. In another example, aerosol spraying can also be used to deposit a wide range of materials with extremely fine (e.g., 4-5 micron) feature size, either on flat substrates or on conformal surfaces. In still another example, ink jet printing technology can also be used to print to flat substrates, which may then be adhered to conformal surfaces. And finally, as another example, screen printing of conductive inks may be used to print to polymer film which is then adhered to a conformal surface. Any combination of such techniques may also be used. Printed electronics allows the use of flexible substrates, which lowers production costs and allows fabrication of mechanically flexible circuits. 
     As shown in  FIG. 2 , a plurality of light sources  206  and  208  are mounted onto the plurality of electrically conductive traces  204  on the planar surface  202  of the substrate  200  at mounting positions  210  and  212  such that the plurality of electrically conductive traces  204  form an electrical interconnection between selected ones of the plurality of electrically conductive traces and associated ones of the plurality of light sources. The electrically conductive traces  204  may comprise groups of circuits, and the light sources  206  and  208  are mounted onto the electrically conductive traces  204  so as to form the groups of circuits. As an example,  FIG. 8  illustrates the substrate with a circuit including light sources  214 ,  216 , and  218 . Multiple circuits may be included based on interconnection of various light sources. 
     The electrically conductive traces interconnect the light sources  206  and  208  with power and control circuitry such that each light source  206  and  208  can be controlled independently of the other, and can be caused to blink or “twinkle.” Alternatively, groups of associated light source in the panel can be controlled independently of each other. 
     The light sources  206  and  208  may include light emitting diodes (LEDs), organic light emitting diodes (OLEDs), other surface mounted devices (SMDs), or a combination of each. The light sources  206  and  208  may be mounted using a conductive adhesive, and the resulting substrate-light source assembly may be cured, e.g., by UV radiation, if UV curing adhesives are used, or alternatively, may be cured with heat, for example, in an autoclave process. 
     As shown in  FIG. 3 , a polymer sheet  220  is provided over the light sources  206  and  208 . The polymer sheet  220  can be a clear polymer sheet, and laid over the light sources  206  and  208  for attachment through a final process (described below). 
     As shown in  FIG. 4 , a composite base  222  is provided upon which a stack-up  224  of the substrate  200  with the printed plurality of electrically conductive traces  204 , the light sources  206  and  208  mounted on the planar surface  202 , and the polymer sheet  220  is applied. The composite base  222  may comprise an existing aircraft structural ceiling panel, made of, e.g., a polycarbonate or polyurethane plastic. As another example, the composite base  222  may comprise a honeycomb core panel. The composite base  222  may include any composite material, such as a lightweight material like an uncured pre-impregnated reinforcing tape or fabric (i.e., “prepreg”). The tape or fabric can include a plurality of fibers such as graphite fibers that are embedded within a matrix material, such as a polymer, e.g., an epoxy or phenolic. The tape or fabric could be unidirectional or woven depending on a degree of reinforcement desired. 
     As shown in  FIG. 5 , using a crush-core process, the light sources  206  and  208  are embedded into the composite base  222  and are also flush with a top surface of the stack-up  224 , and the substrate  200  is also embedded into the composite base  222  underneath the light sources  206  and  208  at the mounting positions  210  and  212 . For example, portions  226  and  228  of the substrate  200  are embedded into the composite base  222  underneath the light sources  206  and  208  at the mounting positions  210  and  212 . 
     The crush core process includes placing the composite base  222  with the stack-up  224  in a large press, and the stack-up  224  is crushed down into the composite base  222  to a predetermined thickness. Example pressures up to 300 psi/20.7 bar cause honeycomb cell walls of the composite base  222  to fold over and flatten, creating more bonding surface area for the stack-up  224 . This method creates panels of consistent thickness, ensuring good fit and finish during installation. Thus, using the crush core process, the stack-up  224  is bonded into the composite base  222  using pressure and heat to cure the bond. 
     As shown in  FIG. 5 , the polymer sheet  220  covers the light sources  206  and  208 . The light sources  206  and  208  are in contact with the polymer sheet  220  and are operated to shine light  230  through the polymer sheet  220 . No holes are provided in the polymer sheet  220  that expose the light sources  206  and  208 . In addition, no pockets or potting of the composite base  222  are required for insertion of the light sources  206  and  208 . Rather, the crush core process embeds the light sources  206  and  208  into the composite base  222  with corresponding portions  226  and  228  of the substrate  200  embedded underneath the light sources  206  and  208  to provide electrical connections. Without the need for pre-drilled holes or pre-formed pockets, additional manufacturing steps can be removed. The ability to integrate the light sources  206  and  208  into the composite base  222  without requiring a pocket or potting of the light sources  206  and  208 , or other apertures or lenses enables the panel to be manufactured more efficiently. 
     As shown in  FIG. 6 , a decorative film can also be applied over the polymer sheet  220  to cover the light sources  206  and  208 . In this example, the decorative film  232  may be a clear or decorative laminate (“declams”) comprising a thin, flexible film, such as Du Pont Tedlar polyvinyl fluoride (PVF). The decorative film  232  also does not require any small apertures, or vias through which the light sources  206  and  208  are respectively exposed. The decorative film  232  can be bonded to the polymer sheet  220  using an adhesive.  FIG. 6  illustrates a completed lighting panel  234 . In other examples, the decorative film  232  may be replaced with a layer painted on for decoration. 
       FIG. 9  shows a flowchart of an example method  300  for manufacturing a lighting panel, according to an example embodiment. Method  300  shown in  FIG. 9  presents an embodiment of a method that, for example, could be used within the processes shown in  FIGS. 1-6 , for example. Method  300  may include one or more operations, functions, or actions as illustrated by one or more of blocks  302 - 310 . Although the blocks are illustrated in a sequential order, these blocks may also be performed in parallel, and/or in a different order than those described herein. Also, the various blocks may be combined into fewer blocks, divided into additional blocks, and/or removed based upon the desired implementation. 
     It should be understood that for this and other processes and methods disclosed herein, flowcharts show functionality and operation of one possible implementation of present embodiments. Alternative implementations are included within the scope of the example embodiments of the present disclosure in which functions may be executed out of order from that shown or discussed, including substantially concurrent or in reverse order, depending on the functionality involved, as would be understood by those reasonably skilled in the art. 
     At block  302 , the method  300  includes printing the plurality of electrically conductive traces  204  onto the planar surface  202  of the substrate  200 . As an example, the electrically conductive traces  204  may be screen printed as silver ink on a Tedlar substrate or other polyvinyl fluoride (PVF) material. The electrically conductive traces  204  may be printed to provide connections to electrical components (or to terminals of electrical components), so that the electrical components can be placed randomly across the substrate  200 . 
     At block  304 , the method  300  includes mounting the plurality of light sources  206  and  208  onto the plurality of electrically conductive traces  204  on the planar surface  202  of the substrate  200  at mounting positions  210  and  212  such that the plurality of electrically conductive traces  204  form an electrical interconnection between selected ones of the plurality of electrically conductive traces and associated ones of the plurality of light sources. The light sources  206  and  208  may be mounted using a conductive epoxy. The electrically conductive traces  204  may be printed to result in groups of circuits, and the light sources  206  and  208  are mounted onto the electrically conductive traces  204  so as to form the groups of circuits. The electrically conductive traces  204  may be printed so as to result in four groups of circuits that are independent and not wired in parallel, for example. 
     At block  306 , the method  300  includes providing the polymer sheet  220  over the plurality of light sources  206  and  208 . The polymer sheet  220  protects the electrically conductive traces  204  and the light sources  206  and  208  from sweep/sand and paint processes applied to a final product of the lighting panel. The polymer sheet  220  can be a clear polymer sheet, and covers the light sources  206  and  208  so that the light sources  206  and  208  are in contact with the polymer sheet  220  and shine light through the polymer sheet  220 . 
     At block  308 , the method  300  includes providing the stack-up  224  of the substrate  200  with the printed plurality of electrically conductive traces  204 , the plurality of light sources  206  and  208  mounted on the planar surface  202 , and the polymer sheet  220  onto the composite base  222 . The composite base  222  may include a honeycomb core panel. 
     At block  310 , the method  300  includes applying pressure and heat to the stack-up  224  and the composite base  222  to embed the plurality of light sources  206  and  208  into the composite base  222  so as to be flush with a top surface of the stack-up  224 , and to embed the substrate  200  into the composite base  222  underneath the plurality of light sources  206  and  208  at the mounting positions  210  and  212 . Pressure and heat may be applied using a crush core process. When the materials are removed from the press, the light sources  206  and  208  are flush with the top surface and embedded into the composite base  222 . 
     The ability to integrate the light sources  206  and  208  into the composite base  222  without requiring pockets or pre-drilled holes formed for the light sources  206  and  208 , and no need for potting of the light sources  206  and  208  allows for integration of the substrate  200  and light sources  206  and  208  into the composite base  222  in a manner to reduce weight, size, and cost of prior systems. Further, with no pockets created, then additional encapsulation with a potting material is also avoided. The light sources  206  and  208  can be crushed directly into the composite base  222  which allows for integration without use of a pocket and potting material and has been shown to provide a better surface finish. 
     In addition, the light sources  206  and  208  are bright enough to not need a hole to be cut in any top layer or coating which further simplifies the design. Thus, there is no need for holes or lenses or other structures to project light through the polymer sheet  220  since the light sources  206  and  208  directly contact the polymer sheet  220 . 
     A decorative film  232 , or paint, may then be applied to a top surface of the polymer sheet  220 , which enables painting by protecting the electronics. Connectors can then be installed for power and operation of the lighting panel. 
     As those of skill in the art will also appreciate, there are numerous other fabrication and assembly options available that will arrive at the same or a substantially similar lighting panel  234  configuration. 
     The lighting panel  234  may include a power and control module insert  236  for supplying electrical power and control signals to the light sources  206  and  208  of the lighting panel  234 . This enables the printed electrically conductive traces  204  to be connected to wiring. Still further, other discrete electrical components, e.g., microprocessors and RF control or transceiver components to power and control the light sources  206  and  208 , can be embedded into the power and control module insert  236 . The power and control module insert  236  may further incorporate terminal input/output connection pads that enable easy electrical interconnection between the power and control module insert  236  and the light sources  206  and  208  via the electrically conductive traces  204 . 
     As those of skill in the art will appreciate, many aircraft systems can provide electrical power and control signals to light fixtures or the lighting panel  234 . Electronics located within the light panel  234 , such as within the power and control module insert  236 , can control color and brightness of emitted light. Pulse width modulation can be used to control brightness of each of the light sources  206  and  208  within the lighting panel  234 . Furthermore, an aircraft ceiling may include many lighting panels, and each lighting panel may be individually controlled. 
     Control over the lighting panel  234  (typically involving overall star field brightness and blink rate) may be effected, for example, by transmitting control commands or settings from the aircraft to the lighting panel  234  via a wireless link and received at the power and control module insert  236 . In one example, the power and control module insert  236  includes a radio receiver that receives such commands or settings. An antenna for the radio may be printed directly on the substrate  200  or on a substrate laminated thereto, along with other electrical conductors and components. 
     In another example, control of the lighting panel  234  may be effected by transmitting control commands or settings from the airplane to the panel via communication over power line (COPL) technology. Electronics of the aircraft superimpose control/setting signals over a power signal to the lighting panel  234 . A COPL transceiver located in the power and control module insert  236  interprets these signals and controls the light sources  206  and  208  accordingly. 
     The lighting panel  234  offers a number of advantages over prior lighting panels. Components of the lighting panel  234  are less expensive (excluding investment in capital equipment). The current manufacturing process has high ergonomic cost factors, including fine detail, repetitive motions and the like which are substantially eliminated in the examples disclosed herein. 
     Additionally, integration of direct write electronics and the electrically conductive traces  204  into the lighting panel  234  has several additional benefits, including reduced panel weight, shorter process flow times, improved durability, a more efficient form factor and improved ergonomics of manufacture. In the past, some aircraft customers have not selected the Starry Sky lighting option because of the weight penalty associated therewith. The lighting panel  234  can provide a weight savings per panel, which, in an aircraft equipped with numerous such panels, results in an appreciable weight savings over prior panels. 
     Further, as described above, in some examples the lighting panel  234  may have a wired supply of electrical power and a wireless, e.g., radio, interface for communication and control. Thus, the lighting panel  234  requires a low voltage electrical interface for power, and power can be tapped from existing sources, such as ceiling wash lights that are typically turned down to low power while the starry sky effect is operating. Tapping power from local sources and providing wireless control simplifies retrofit of existing aircraft by reducing the need to run additional aircraft wiring. 
     While various examples of the lighting panel disclosed herein are described and illustrated in the context of aircraft interior ceiling lighting systems, it will be evident that they are not limited to this particular application, but may be used in a variety of other applications, e.g., other aircraft surfaces, such as entry area ceilings, destination spaces, or even in non-aerospace applications, such as dance halls theaters residential ceilings, advertisements, and the like. 
     Referring now to  FIGS. 10-14 , an example process is shown for manufacturing a composite panel, according to an example embodiment. In  FIG. 10 , a trace sheet  400  is shown again that has a planar surface  402 . The planar surface  402  provides a relatively smooth surface or substantially flat surface. The plurality of electrically conductive traces  204  are printed onto the planar surface  402  of the substrate  400  as described above and shown in  FIG. 7 . The electrically conductive traces  204  can be written on the planar surface  402  of the trace sheet  400  so as to make electrical connections with respective leads of electrical components. 
     The trace sheet  400  may comprise a substrate, similar to the substrate  200  described above. 
     Following, a plurality of transducer discs  404  and  406  are positioned onto the electrically conductive traces  204  at positions such that the electrically conductive traces  204  form an electrical interconnection between selected ones of the electrically conductive traces and associated ones of the transducer discs. The electrically conductive traces  204  may comprise groups of circuits, and the transducer discs  404  and  406  are mounted onto the electrically conductive traces  204  so as to form the groups of circuits. Thus, the trace sheet  400  includes the electrically conductive traces  204  and the plurality of transducer discs  404  and  406  printed thereon. 
     In one example, the transducer discs  404  and  406  include piezo-electric microphone components printed on the trace sheet  400 . For instance, the transducer discs  404  and  406  may include acoustic-to-electric transducers that convert sound into an electrical signal as a microphone. In another example, the transducer discs  404  and  406  include electroacoustic transducers that convert an electrical audio signal into a corresponding sound as a loud-speaker. And, in yet another example, the trace sheet  400  includes many transducer discs, and some of the transducer discs are acoustic-to-electric transducer discs as microphones and some of the transducer discs are electroacoustic transducers as loud-speakers. 
     The electrically conductive traces  204  interconnect the transducer discs  404  and  406  with power and control circuitry such that each transducer disc  404  and  406  can be controlled independently of the other. Alternatively, groups of associated transducer discs  404  and  406  can be controlled together. 
     As shown in  FIG. 11 , a plurality of plies  400 ,  408 ,  410 , and  412  are assembled in a stack-up  414 . The trace sheet  400  is included as an internal ply in the stack-up  414  of the plurality of plies. Other plies in the stack-up  414  can include a first glass layer  408 , a second glass layer  410 , and a polymer sheet  412 . The polymer sheet  412  may be a clear cap Tedlar layer. 
     As shown in  FIG. 12 , the stack-up  414  of the plurality of plies  400 ,  408 ,  410 , and  412  is applied to a composite base  416 . The stack-up  414  of the plurality of plies  400 ,  408 ,  410 , and  412  is then cured upon the composite base  416  to integrate the trace sheet  400  and the plurality of transducer discs  404  and  406  into the composite base  416 .  FIG. 13  illustrates the trace sheet  400  and the plurality of transducer discs  404  and  406  integrated into the composite base  416 . 
     The composite base  416  includes a honeycomb core panel, such as Nomex honeycomb core (made from aramid fiber paper supplied by DuPont Advanced Fibers Systems, Richmond, Va.). The composite base  416  may include any composite material, such as a lightweight material like an uncured pre-impregnated reinforcing tape or fabric (i.e., “prepreg”). The tape or fabric can include a plurality of fibers such as graphite fibers that are embedded within a matrix material, such as a polymer, e.g., an epoxy or phenolic. The tape or fabric could be unidirectional or woven depending on a degree of reinforcement desired. 
     The stack-up  414  may be cured upon the composite base  416  using a crush-core process as described above. As shown in the example configuration at  FIG. 13 , the composite base  416  can be faced with two skin plies of glass  408  and  410  for added strength. The polymer sheet  412  may be a final layer, and the trace sheet  400  is provided in the stack-up  414  between the polymer sheet  412  and the composite base  416 . In other examples, as shown in  FIG. 13 , a paint or decorative film  418  can also be applied over the polymer sheet  412 . In this example, the decorative film  418  may be a clear or decorative laminate (“declams”) comprising a thin, flexible film, such as Du Pont Tedlar polyvinyl fluoride (PVF). The decorative film  418  can be bonded to the polymer sheet  412  using an adhesive.  FIG. 14  illustrates one example completed composite panel  420 . 
       FIG. 15  illustrates a side view of the trace sheet  400 , according to an example embodiment. A configuration of the electrically conductive traces  204  and the transducer discs  404  and  406  is shown as one example. In  FIG. 15 , other plies of the stack-up  414  are not shown. 
       FIG. 16  illustrates a detailed side view of one of the transducer discs, such as the transducer disc  404 . Initially, a bottom conductive trace  422  is printed onto the trace sheet  400 , and then a piezo-electric material  424  is printed onto the bottom conductive trace  422 , and then a top conductive trace  426  is printed onto the piezo-electric material  424 . Example piezo electric materials include PZT (Lead Zirconium Titanate), BaTiO 3  (Barium Titanate), and PVDF (Polyvinylidene Flouride). 
     Using printed electronics technology, the transducer discs  404  and  406  can be printed onto the trace sheet  400  along with the electrically conductive traces  204 . When formed as microphones, the transducer discs  404  and  406  compress due to received sounds waves causing a change in voltage. Strains from pressure changes that originate from acoustic waves can be measured. Voltage changes are then converted back to digital sound. 
     A diameter of the transducer discs  404  and  406  can be optimized for a specific sound frequency range. 
     The transducer discs  404  and  406  can be used as input devices as microphones or output devices as speakers, and the difference in use is based on a size of the transducer discs  404  and  406 . A larger size generally will have a larger impedance/resistance value and can be used as a loud-speaker. A smaller size generally will have a smaller impedance/resistance value and can be used as a microphone. Thus, some of the transducer discs  404  and  406 , and many others that can be included on the trace sheet  400  as well can be configured as microphones, and some of the transducer discs can be configured as speakers to enable a two-way communication device. Thus, the trace sheet  400  may include any number of microphone discs and loud-speaker discs in any combination. 
       FIG. 17  illustrates a side view of another example of the trace sheet  400 . In this example, the transducer discs  404  and  406  may be configured as microphones. Then, a second plurality of electrically conductive traces  430  are included on the trace sheet  400 , and a plurality of loud-speaker transducers  432  and  434  positioned onto the second plurality of electrically conductive traces  430  at positions such that the second plurality of electrically conductive traces  430  form an electrical interconnection between selected ones of the second plurality of electrically conductive traces and associated ones of the plurality of loud-speaker transducers. In this example, the loud-speaker transducers  432  and  434  include electroacoustic transducers that convert an electrical audio signal into a corresponding sound as a loud-speaker. Further, in this example, the trace sheet  400  includes both microphone transducer discs  404  and  406 , as well as loud-speaker transducers  432  and  434  to enable two-way communication. The electrically conductive traces  204  and the electrically conductive traces  430  may comprise independent circuits enabling independent operation of the microphone transducer discs  404  and  406  and the loud-speaker transducers  432  and  434 . 
       FIG. 18  illustrates a side view of another example of the trace sheet  400 . In this example, the transducer discs  404  and  406  may be configured as microphones or as loud-speakers, or as a combination of microphones and loud-speakers. Then, a second plurality of electrically conductive traces  440  can be included on the trace sheet  400  and a plurality of light sources  442  and  444  can be mounted onto the second plurality of electrically conductive traces  440  at light mounting positions such that the second plurality of electrically conductive traces form an electrical interconnection between selected ones of the second plurality of electrically conductive traces and associated ones of the plurality of light sources. As described above with reference to  FIGS. 6-8 , the plurality of light sources  442  and  444  are embedded into the composite base  416 . The electrically conductive traces  204  and the electrically conductive traces  440  may comprise independent circuits enabling independent operation of the transducer discs  404  and  406  and the light sources  442  and  444 . 
       FIG. 19  illustrates a side view of another example of the trace sheet  400 . In this example, the transducer discs  404  and  406  may be configured as microphones, and the plurality of light sources  442  and  444  can be mounted onto the trace sheet  400  as well. Then, a third plurality of electrically conductive traces  450  may be included and a plurality of loud-speaker transducers  452  and  454  are positioned onto the third plurality of electrically conductive traces  450  at positions such that the third plurality of electrically conductive traces form an electrical interconnection between selected ones of the third plurality of electrically conductive traces and associated ones of the plurality of loud-speaker transducers. The plurality of loud-speaker transducers  452  and  454  include electroacoustic transducers that convert an electrical audio signal into a corresponding sound as a loud-speaker. In this example, the trace sheet  400  includes microphones, loud-speakers, and light sources all embedded therein, and the electrically conductive traces  204 ,  440  and  450  may comprise independent circuits enabling independent operation of the transducer discs  404  and  406 , the light sources  442  and  444 , and the loud-speaker transducers  452  and  454 . Although the transducer discs  404  and  406 , the light sources  442  and  444 , and the loud-speaker transducers  452  and  454  are shown arranged in separate rows, any configuration or layout of these components may be provided. 
     The composite panel thus may include any combination of microphone or loud-speaker transducer discs and light sources seamlessly integrated into the panel. The composite panel may comprise an aircraft wall, ceiling panel, or other aircraft interior structure such as stowbins, monuments, valences, etc. Further, the composite panel may be used in ceilings and sidewalls of aircraft or other vehicles (e.g., headliner of cars). Still further, the composite panel may be used for any architectural panel or structure such as a conference room wall or table or even smaller items such as cell phone cases or covers, for example. The composite panel is lightweight, inexpensive, and easy to manufacture and assemble. 
       FIG. 20  shows a flowchart of an example method  500  for manufacturing a composite panel, according to an example embodiment. Method  500  shown in  FIG. 20  presents an embodiment of a method that, for example, could be used within the processes shown in  FIGS. 10-17 , for example. Method  500  may include one or more operations, functions, or actions as illustrated by one or more of blocks  502 - 508 . Although the blocks are illustrated in a sequential order, these blocks may also be performed in parallel, and/or in a different order than those described herein. Also, the various blocks may be combined into fewer blocks, divided into additional blocks, and/or removed based upon the desired implementation. 
     It should be understood that for this and other processes and methods disclosed herein, flowcharts show functionality and operation of one possible implementation of present embodiments. Alternative implementations are included within the scope of the example embodiments of the present disclosure in which functions may be executed out of order from that shown or discussed, including substantially concurrent or in reverse order, depending on the functionality involved, as would be understood by those reasonably skilled in the art. 
     At block  502 , the method  500  includes printing electrically conductive traces  204  onto a planar surface  402  of a trace sheet  400 . 
     At block  504 , the method  500  includes positioning a plurality of transducer discs  404  and  406  onto the electrically conductive traces  204  at positions such that the electrically conductive traces  204  form an electrical interconnection between selected ones of the electrically conductive traces and associated ones of the transducer discs. In one example, positioning the plurality of transducer discs  404  and  406  onto the electrically conductive traces  204  includes, for each of the plurality of transducer discs  404  and  406  printing a bottom conductive trace  422  onto the trace sheet  400 , printing a piezo-electric material  424  onto the bottom conductive trace  422 , and printing a top conductive trace  426  onto the piezo-electric material  424 . In another example, the plurality of transducer discs  404  and  406  can be mounted to the trace sheet  400 . 
     As described above, the plurality of transducer discs  404  and  406  can include acoustic-to-electric transducers that convert sound into an electrical signal as a microphone, electroacoustic transducers that convert an electrical audio signal into a corresponding sound as a loud-speaker, or a combination of microphone and loud-speaker transducers. 
     At block  506 , the method  500  includes positioning a stack-up  414  of a plurality of plies  400 ,  408 ,  410 , and  412  onto a composite base  416 , and the plurality of plies  400 ,  408 ,  410 , and  412  includes the trace sheet  400  with the printed electrically conductive traces  204  and the plurality of transducer discs  404  and  406 , and the trace sheet  400  is included as an internal ply in the stack-up  414  of the plurality of plies. One of the plurality of plies includes a polymer sheet  412 , and the trace sheet  400  is provided in the stack-up  414  between the polymer sheet  412  and the composite base  416 . 
     At block  508 , the method  500  includes applying pressure and heat to the stack-up  414  and the composite base  416  to cure the plurality of plies  400 ,  408 ,  410 , and  412  upon the composite base  416  and to integrate the trace sheet  400  and the plurality of transducer discs  404  and  406  into the composite base  416 . 
       FIG. 21  shows a flowchart of another example method  520  for manufacturing a composite panel, according to an example embodiment. Method  520  shown in  FIG. 21  presents an embodiment of a method that, for example, could be used within the processes shown in  FIGS. 10-18 , for example. Method  520  may include one or more operations, functions, or actions as illustrated by one or more of blocks  522 - 526 . Although the blocks are illustrated in a sequential order, these blocks may also be performed in parallel, and/or in a different order than those described herein. Also, the various blocks may be combined into fewer blocks, divided into additional blocks, and/or removed based upon the desired implementation. 
     The method  520  may be performed in addition to the method  500  as described in  FIG. 20 . 
     At block  522 , the method  520  includes printing a second plurality of electrically conductive traces  440  onto the planar surface of the trace sheet  400 . 
     At block  524 , the method  520  includes positioning a plurality of light sources  442  and  444  onto the second plurality of electrically conductive traces  440  on the planar surface of the trace sheet  400  at light mounting positions such that the second plurality of electrically conductive traces  440  form an electrical interconnection between selected ones of the second plurality of electrically conductive traces and associated ones of the plurality of light sources. 
     At block  526 , the method  520  includes applying pressure and heat to the stack-up  414  and the composite base  416  to cure the plurality of plies  400 ,  408 ,  410 , and  412  upon the composite base  416  and to embed the plurality of light sources  442  and  444  into the composite base  416 . 
     Thus, using the method  520 , the composite panel can be manufactured to include both light sources  442  and  444  and transducer discs  404  and  406 , as shown in  FIG. 18 . The transducer discs  404  and  406  may be configured as microphones or loud-speakers for use in addition to the light sources  442  and  444 . Thus, the composite panel may be manufactured with the light sources  442  and  444  and microphones, or with the light sources  442  and  444  and loud-speakers, or with all of the light sources  442  and  444 , microphones, and loud-speakers (additionally described below with reference to  FIG. 23 ). 
       FIG. 22  shows a flowchart of another example method  530  for manufacturing a composite panel, according to an example embodiment. Method  530  shown in  FIG. 22  presents an embodiment of a method that, for example, could be used within the processes shown in  FIGS. 10-17 , for example. Method  530  may include one or more operations, functions, or actions as illustrated by one or more of blocks  532 - 536 . Although the blocks are illustrated in a sequential order, these blocks may also be performed in parallel, and/or in a different order than those described herein. Also, the various blocks may be combined into fewer blocks, divided into additional blocks, and/or removed based upon the desired implementation. 
     The method  530  may be performed in addition to the method  500  as described in  FIG. 20  in instances in which the plurality of transducer discs  404  and  406  includes acoustic-to-electric transducers that convert sound into an electrical signal as a microphone. 
     At block  532 , the method  530  includes printing a second plurality of electrically conductive traces  430  onto the planar surface  402  of the trace sheet  400 . 
     At block  534 , the method  530  includes positioning a plurality of loud-speaker transducers  432  and  434  onto the second plurality of electrically conductive traces  430  on the planar surface  402  of the trace sheet  400  at positions such that the second plurality of electrically conductive traces  430  form an electrical interconnection between selected ones of the second plurality of electrically conductive traces and associated ones of the plurality of loud-speaker transducers. The plurality of loud-speaker transducers  432  and  434  include electroacoustic transducers that convert an electrical audio signal into a corresponding sound as a loud-speaker. 
     At block  536 , the method  530  includes applying pressure and heat to the stack-up  414  and the composite base  416  to cure the plurality of plies  400 ,  408 ,  410 , and  412  upon the composite base  416  and to embed the plurality of loud-speaker transducers  432  and  434  into the composite base  416 . 
     Thus, using the method  530 , the composite panel can be manufactured to include both loud-speaker transducers  432  and  434  and transducer discs  404  and  406  as microphones, as shown in  FIG. 17 , to enable two-way communication. 
       FIG. 23  shows a flowchart of another example method  540  for manufacturing a composite panel, according to an example embodiment. Method  540  shown in  FIG. 23  presents an embodiment of a method that, for example, could be used within the processes shown in  FIGS. 10-19 , for example. Method  540  may include one or more operations, functions, or actions as illustrated by one or more of blocks  542 - 556 . Although the blocks are illustrated in a sequential order, these blocks may also be performed in parallel, and/or in a different order than those described herein. Also, the various blocks may be combined into fewer blocks, divided into additional blocks, and/or removed based upon the desired implementation. 
     At block  542 , the method  540  includes printing electrically conductive traces  204  onto a planar surface  402  of a trace sheet  400 . 
     At block  544 , the method  540  includes positioning a plurality of transducer discs  404  and  406  onto the electrically conductive traces  204  at positions such that the electrically conductive traces  204  form an electrical interconnection between selected ones of the electrically conductive traces and associated ones of the transducer discs. In this example, the plurality of transducer discs  404  and  406  include acoustic-to-electric transducers that convert sound into an electrical signal as a microphone. 
     At block  546 , the method  540  includes printing a second plurality of electrically conductive traces  430  onto the planar surface of the trace sheet  400 . 
     At block  548 , the method  540  includes positioning a plurality of loud-speaker transducers  432  and  434  onto the second plurality of electrically conductive traces  430  on the planar surface  402  of the trace sheet  400  at positions such that the second plurality of electrically conductive traces  430  form an electrical interconnection between selected ones of the second plurality of electrically conductive traces and associated ones of the plurality of loud-speaker transducers. The plurality of loud-speaker transducers  432  and  434  include electroacoustic transducers that convert an electrical audio signal into a corresponding sound as a loud-speaker. 
     At block  550 , the method  540  includes printing a third plurality of electrically conductive traces  440  onto the planar surface  402  of the trace sheet  400 . 
     At block  552 , the method  540  includes positioning a plurality of light sources  442  and  444  onto the third plurality of electrically conductive traces  440  on the planar surface of the trace sheet  400  at light mounting positions such that the third plurality of electrically conductive traces  440  form an electrical interconnection between selected ones of the third plurality of electrically conductive traces and associated ones of the plurality of light sources. 
     At block  554 , the method  540  includes positioning a stack-up  414  of a plurality of plies  400 ,  408 ,  410 , and  412  onto a composite base  416 , and the plurality of plies  400 ,  408 ,  410 , and  412  includes the trace sheet  400  as an internal ply in the stack-up  414  of the plurality of plies. One of the plurality of plies includes a polymer sheet  412 , and the trace sheet  400  is provided in the stack-up  414  between the polymer sheet  412  and the composite base  416 . 
     At block  556 , the method  540  includes applying pressure and heat to the stack-up  414  and the composite base  416  to cure the plurality of plies  400 ,  408 ,  410 , and  412  upon the composite base  416  and to integrate the trace sheet  400  and the plurality of transducer discs  404  and  406  as well as the loud-speaker transducers  432  and  434  and light sources  442  and  444  into the composite base  416 . 
     Thus, using the method  540 , the composite panel can be manufactured to include loud-speaker transducers  432  and  434  and transducer discs  404  and  406  as microphones, as well as light sources  442  and  444  as shown in  FIG. 19 . 
     As described above, using any of the methods in which both microphone and loud-speaker transducers are included allows for the composite panel to operate as a two-way communication device. Further, the composite panel includes the one trace sheet  400  with any combination of selected components such as the transducer discs  404  and  406  as microphones, the loud-speaker transducers  432  and  434 , and the light sources  442  and  444 . 
     The description of the different advantageous arrangements has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the embodiments in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art. Further, different advantageous embodiments may describe different advantages as compared to other advantageous embodiments. The embodiment or embodiments selected are chosen and described in order to explain the principles of the embodiments, the practical application, and to enable others of ordinary skill in the art to understand the disclosure for various embodiments with various modifications as are suited to the particular use contemplated.