Abstract:
Techniques for applying graphic images to a surface are disclosed. In one aspect, a method includes receiving an image file from an image source and generating a surface model that describes geometrical contours of the surface. An applicator is then controlled according to the surface model, and the graphic image is applied that corresponds to the image file.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This patent application is a divisional application of co-pending, commonly owned U.S. patent application No. 10/926,801 entitled “Apparatus and Methods for Applying Images to a Surface,” filed on Aug. 26, 2004, which application is incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    This disclosure relates generally to the application of graphic images, and, more specifically, to methods for applying graphic images to a surface. 
       BACKGROUND 
       [0003]    In various commercial products, it is desirable to impart colorful visual effects through the application of a pigmented formulation to a surface to form an aesthetically appealing image. The image may be applied to the surface by various methods, including applying a paint material to the surface by means of a brush or an aerosol spray. Alternately, other methods may be used that avoid painting processes altogether. For example, an applique or a decal having the desired image formed thereon may be adhered to the surface. 
         [0004]    The foregoing conventional methods have been widely used to apply images to an exterior portion of an aircraft. For example, images may be applied to wing, fuselage and tail surfaces of the aircraft for decorative and/or functional purposes. Since the images are typically large and often detailed, skilled personnel are required to paint or adhere an image to an exterior portion of the aircraft. Consequently, the production cost of an aircraft is increased due to the additional labor cost associated with painting or adhering an image to the exterior portion of the aircraft. 
         [0005]    Other shortcomings stem from the foregoing processes, which will now be described in detail.  FIG. 1  is a partial cross-sectional view of an external portion  10  of an aircraft having a painted image applied thereon, according to the prior art. The external portion  10  includes a supporting surface  12 , which is typically a structural portion of the aircraft, such as a fuselage panel, a wing panel, or other external surfaces of the aircraft, and a plurality of paint layers  14  that are applied to the supporting surface  12 . The paint layers  14  may include a primer layer  16 , a base color layer  18 , and a plurality of decorative color layers  20  that collectively form the painted image on the external portion  10 . 
         [0006]    One significant shortcoming present in this method is that the paint layers  14  are generally successively applied to the supporting surface  12 , so that a time-consuming drying period is required between successive paint applications, thus increasing the production time for the aircraft. Further, the application of the decorative color layers  20  additionally requires the application of paint masking devices such as stencils, or tape between successive applications of the layers  20 , which requires still more time and labor. Since spray application devices may only apply a single color portion of the image, the spray application device must be cleaned numerous times before image is complete, thus requiring still more time and labor. 
         [0007]    Still other shortcomings are inherent in the image itself when the image is applied by the foregoing method. For example, the application of the decorative color layers  20  generally results in an external surface  22  having surface irregularities  24 . Since the external surface  22  is exposed to a slipstream while the aircraft is in flight, the surface irregularities  24  generate additional surface drag on the aircraft that results in increased fuel consumption for the aircraft. Although appliques, such as decals and other similar preformed images have been widely used for applying images to aircraft, and generally present a smooth external surface to the slipstream, appliques are susceptible to premature degradation through prolonged exposure to ultraviolet radiation that results in fading and/or discoloration of the image. In addition, appliques may partially detach from the aircraft surface, particularly along exposed edges of the applique, so that maintenance costs for the aircraft are increased. 
         [0008]    Therefore, there is an unmet need in the art for systems and methods for forming an image on an aircraft exterior that results in lower production and maintenance costs, while providing an image that is generally superior to those currently produced. 
       SUMMARY 
       [0009]    Techniques for applying graphic images to a surface are disclosed. In one aspect, a method includes receiving an image file from an image source and generating a surface model that describes geometrical contours of the surface. An applicator is then controlled according to the surface model, and the graphic image is applied that corresponds to the image file. In another aspect, a method includes identifying the exposed portion of the structure and applying at least one layer of a first coating material having a uniform color onto the identified structure. A graphics layer is deposited onto the at least one layer of a first coating material and a layer of an at least partially transparent second coating material is applied onto the graphics layer. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0010]    The preferred and alternative embodiments of the present disclosure are described in detail below with reference to the following drawings. 
           [0011]      FIG. 1  is a partial cross-sectional view of an external portion of an aircraft having a painted image applied thereon, according to the prior art; 
           [0012]      FIG. 2  is a block diagrammatic view of a system for applying a graphic image to a surface according to an embodiment of the disclosure; 
           [0013]      FIG. 3  is an isometric view of an actuator according to another embodiment of the disclosure, which may be used with the system of  FIG. 2 ; 
           [0014]      FIG. 4  is a schematic view of an applicator supply system according to still another embodiment of the disclosure that may be used with the system of  FIG. 2 ; 
           [0015]      FIG. 5  is a plan view of an applicator head according to still another embodiment of the disclosure that may form a portion of the applicator of  FIG. 2 ; 
           [0016]      FIG. 6  is a block diagrammatic view of a controller according to still another embodiment of the disclosure that may be used with the system of  FIG. 2 ; 
           [0017]      FIG. 7  is a partial cross-sectional view of an external portion of an aircraft that will be used to describe a method of applying an image to an aircraft according to another embodiment of the disclosure; and 
           [0018]      FIG. 8  is a side elevation view of an aircraft having at least one graphic image according to an embodiment of the disclosure. 
       
    
    
     DETAILED DESCRIPTION  
       [0019]    The present disclosure relates to the application of images to a surface and, more specifically, to systems and methods for applying decorative images to an aircraft surface. Many specific details of certain embodiments of the disclosure are set forth in the following description and in  FIGS. 2 through 8  to provide a thorough understanding of such embodiments. One skilled in the art, however, will understand that the present disclosure may have additional embodiments, or that the present disclosure may be practiced without several of the details described in the following description. 
         [0020]      FIG. 2  is a block diagrammatic view of a system  30  for applying a graphic image to a surface according to an embodiment of the disclosure. The system  30  includes an applicator  32  operable to apply pigmented formulations such as inks of various colors to a surface  34 . The applicator  32  will be described in greater detail below. The applicator  32  is coupled to an actuator (or other suitable motivating device)  36  that is configured to move the applicator  32  in a transverse direction relative to the surface  34  by moving the applicator  32  in an x-direction and a y-direction. The actuator  36  may also move the applicator  32  in a perpendicular direction relative to the surface  34  by moving the applicator  32  in a z-direction. The actuator  36  may comprise any positioning device operable to receive positioning instructions and configured to position the applicator  32  in the instructed position. In one specific embodiment, the actuator is a programmable manipulator such as robotic device capable of at least three-axis motion. In another embodiment, the actuator  36  comprises a three-axis translational device that will also be described in further detail below. The actuator  36  is coupled to a controller  38  operable to receive image information  40  and control the motion of the actuator  36 . The controller  38  is also operable to control an applicator supply system  42  that supplies a liquid pigmented material to the applicator  32 . The applicator supply system  42  will be described in further detail below. The controller  38  is further coupled to the applicator  32  in order to control the operation of the applicator  32 , as will also be described in detail below. 
         [0021]      FIG. 3  is an isometric view of an actuator  50  according to another embodiment of the disclosure, which may be used with the system  30  of  FIG. 2 . The actuator  50  includes a first frame  52  and a second frame  54  that is coupled to the first frame  52  to form a rigid unitary structure. The first frame  52  is spaced apart from the second frame  54  to permit a fin portion  56  of an aircraft enpennage to be interposed between the first frame  52  and the second frame  54 . The actuator  50  is further configured to rest on a support platform  58  adjacent to the fin portion  56 . In this embodiment, the actuator  50  also includes vacuum retainers  60  configured to retain the actuator  50  in a fixed position relative to the fin portion  56 . In particular, the vacuum retainers  60  are configured to hold the actuator  50  in proper registration with an image  62  formed on the fin portion  56  by the applicator  32 . The vacuum retainers  60  form an enclosed volume when the retainers  60  are moved into a sealable relationship with the fin portion  56 , which is evacuated by a vacuum pump (not shown in  FIG. 3 ) in order to restrain relative movement between the actuator  50  and the fin portion  56 . 
         [0022]    The first frame  52  and the second frame  54  have a first guide  64  that guides the applicator  32  in the x-direction as it is moved. The first frame  52  and the second frame  54  also include a second guide  66  to guide the applicator  32  in the y-direction as it is moved. Accordingly, the first guide  64  and the second guide  66  also include translation devices (not shown in  FIG. 3 ) operable to move the applicator  32  along the first guide  64  and the second guide  66 . For example, the translation devices may include a ball-bearing screw translation device, as is well understood in the art, although other linear translation devices are available. The first frame  52  and the second frame  54  also include a linear translator  66  operable to move the applicator  32  in the z-direction. The linear translator  66  may also include a ball-bearing screw translation device, although other linear translation devices may be used. 
         [0023]    Although the actuator  50  shown in  FIG. 3  is configured to apply the image  62  on opposing sides of the aircraft fin  56 , it is understood that, in other embodiments, the actuator  50  may include a single applicator  32  positioned on one of the first frame  52  and the second frame  54 . Moreover, the actuator  50  of  FIG. 3  includes a substantially linear first guide  64  and a substantially linear second guide  66 . In other embodiments, the first guide  64  and/or the second guide  66  may be curved to conform to other structural shapes. For example, the second linear guide  66  may have a substantially curved shape while the first guide  64  is linear, so that the actuator  50  may be used to apply an image to a curved structural portion, such as a portion of an aircraft fuselage. 
         [0024]      FIG. 4  is a schematic view of an applicator supply system  70  according to still another embodiment of the disclosure that may be used with the system  30  of  FIG. 2 . The applicator supply system  70  includes a bulk supply reservoir  72  that contains a volume of a pigmented formulation, such as ink, or other similar materials. The bulk supply reservoir  72  includes a level sensor  74  that is operable to sense a liquid level within the bulk supply reservoir  72  and generate a signal when the liquid level falls below a predetermined level. The bulk supply reservoir  72  also includes a fill port  76  to permit the pigmented formulation to be replenished. The fill port  76  may also be configured with an atmospheric vent to equalize a pressure within the bulk supply reservoir  72  with an atmospheric pressure. The bulk supply reservoir  72  is coupled to a feeder reservoir  78  by a supply line  80 . Since the bulk supply reservoir  72  and the feeder reservoir  78  may be positioned at different relative elevations, a supply pump  82  is positioned in the supply line  80  to move the pigmented material from the bulk supply reservoir  72  to the feeder reservoir  78 . The supply line  80  may also include a filter  84  to remove foreign material or agglomerated pigments from the material in the bulk supply reservoir  72 . The feeder reservoir  78  also includes a level sensor  86  that is operable to sense a liquid level within the feeder reservoir  78  and generate a signal when the liquid level falls below a predetermined level. An atmospheric vent  88  is positioned on the feeder reservoir  78  to equalize an internal pressure within the feeder reservoir  78  with an atmospheric pressure. 
         [0025]    The feeder reservoir  78  is coupled to the applicator  32  (as shown in  FIG. 2 ) having at least one applicator head  90  by distribution lines  92 . The applicator head  90  will be discussed in greater detail below. An applicator pump  94  moves a liquid stored within the feeder reservoir  78  to the applicator  32 , and further provides a pressure that is sufficient to atomize the liquid that is supplied to the at least one applicator head  90 . A distribution manifold may be positioned in the distribution lines  92  to permit more than a single applicator head  90  to be supplied. The distribution manifold  96  may also be coupled to a return line  98  that permits liquid to return to the reservoir  78 , thus avoiding excessive liquid pressures at the at least one applicator head  90 , and also advantageously allowing the pigmented formulation stored within the reservoir  78  to remain well-mixed. A solenoid valve  100  may also be positioned in the return line  98  that may be closed during periods when the applicator supply system  70  is not operating, in order to prevent liquid within the distribution lines  92  from moving back into the reservoir  78  by gravitational action. Flow meters  102  operable to generate a signal when a liquid is in motion within the distribution lines  92  may be positioned near the at least one applicator head  90  in order to detect the absence of a liquid flow in the distribution lines  92 . 
         [0026]      FIG. 5  is a plan view of an applicator head  110  according to still another embodiment of the disclosure that may form a portion of the applicator  32  of  FIG. 2 . The applicator head  110  includes a plurality of liquid jet heads  112  operable to emit droplets a pigmented ink or other like materials towards a surface  113  upon which an image is to be transferred. In some embodiments, each of the plurality of liquid jet heads  112  may be coupled to a separate applicator supply system  70  ( FIG. 4 ) to dispense a selected color. For example, the applicator head  110  may be coupled to four separate applicator supply systems  70  to provide black, yellow, magenta and cyan-colored inks to the applicator head  110 . The plurality of liquid jet heads  112  are also coupled to a plurality of activation lines  114  to transfer an activation signal from the controller  38  (as shown in  FIG. 2 ) to a selected one of the liquid jet heads  112 . The liquid jet heads  112  comprising the applicator head  110  are generally configured to deliver approximately 200 dots-per-inch resolution by generating droplets of the pigmented ink having a typical volume of approximately 80 pico-liters per droplet. One suitable applicator head is the commercially available XJ126 applicator head manufactured by Xaar PLC of Cambridge, UK, although other suitable applicator heads may also be used. 
         [0027]    The applicator head  110  may also include at least one ultraviolet (UV) light source  116  positioned proximate to the liquid jet heads  112  and operable to project UV radiation towards the surface  113  in order to accelerate polymerization of a UV-cured ink. The UV light source  116  may also include a shutter mechanism to interrupt the emission of UV light from the source  116  so that the polymerization process may be interrupted. A proximity sensor  118  is coupled to the applicator head  110  that is operable to sense a distance ‘d’ between the applicator head  110  and the surface  113 . Accordingly, the proximity sensor  118  may be comprised of an inductive proximity sensor, a capacitive proximity sensor, or an ultrasonic proximity sensor, all of which are available from the Allen-Bradley Co. of Milwaukee, Wis. The applicator head  110  may also include an optical detector  120  that is operable to view a portion of the surface  113  while an image is applied to the surface  113 . The optical detector  120  may include an integral light source for illumination of the surface  113 , such as a white light emitting diode (LED) or other similar light source. The applicator head  110  may also include a mechanical stop  122  to prevent the liquid jet heads  112  from contacting the surface  113 . Accordingly, the mechanical stop  122  may include a spring that biases a wheel against the surface  113  and is further configured to prevent positioning the liquid jet heads  112  at a distance less than ‘d min ’ from the surface  113 . 
         [0028]      FIG. 6  is a block diagrammatic view of a controller  130  according to still another embodiment of the disclosure that may be used with the system  30  of  FIG. 2 . The controller  130  includes a personal computing device  132  such as the Dimension XPS personal computer system available from Dell Inc. of Houston, Tex., although other suitable alternatives exist. The personal computing device  132  is configured to receive image information  40  through a communications line, such as a 100 bT Ethernet communications line. The image information  40  may be formatted in the well-known tagged image file format (TIFF), or in other suitable formats, such as the standard bit-mapped graphics format (BMP) or PCX. The image information  40  may also include structural models, such as CATIA files that describe geometric details of an image surface. The personal computing device  132  is coupled to a peripheral component interconnect (PCI) board  134  to permit high speed digital communication between the personal computing device  132  and a printer interface unit  136 . The printer interface unit  136  controls the applicator  32  (as shown in  FIG. 2 ). For example, and with reference also to  FIG. 4 , the printer interface unit  136  is configured to accept signals generated by the level sensor  74 , the level sensor  86  and the flow sensors  102  and to control the pump  94 . The unit  136  is further configured to control the actuator (or other suitable motivating device)  36  (as shown in  FIG. 2 ) by generating motion control commands  137  and vacuum system commands  138 . The printer interface  136  is further coupled to a head interface board  138  that controls the functions of the applicator head  110  (as shown in  FIG. 5 ). For example, a UV detect signal  139  is received by the head interface board  138  through the printer interface  136  to control the UV light source  116  (as shown in  FIG. 5 ) and to control the shutter associated with the UV light source  116 . The head interface board  138  may also be configured to receive a media detect signal  140  that indicates a surface is proximate to the applicator head  110 . The head interface board  138  may also receive an encoder signal  141  that may be used to calculate a position corresponding to a next pixel to be printed. The media detect signal  140  and the encoder signal  141  are generated by the optical detector  120 , which is coupled to the applicator head  110  (as shown in  FIG. 5 ). 
         [0029]    With reference still to  FIG. 6 , the operation of the controller  130  will be discussed in greater detail. The image information  40  includes an image file is created through the use of existing image software, such as Adobe Photoshop, available from Adobe Systems Inc. of San Jose, Calif., or CorelDRAW, available from Corel Corp. of Dallas Tex. The image file may be presented to the controller  130  in discrete parts, or “tiles”, or it may be presented to the controller  130  as a single file that encompasses the entire image. The image information  40  may also include a three-dimensional surface model that describes the surface upon which the image is to be applied. The three-dimensional surface model may be generated by moving the applicator  32  across the surface and scanning the surface with the optical detector  120  and/or the proximity sensor  118  to compile a surface map of the aircraft portion that is to receive the image. Once a surface map is generated, it may be stored in the personal computing device  132  or it may be uploaded to a different storage location. Alternately, a pre-existing CATIA model that describes the structural details of a selected portion of the aircraft may be transferred to the controller  130  and used as a three-dimensional surface model. In another approach, a pre-existing surface model may be utilized as a general guide to the surface structure, with the optical detector  120  and/or the proximity sensor  118  scanning the surface to provide information regarding minor discrepancies in surface contour that may exist between the surface model and the aircraft in the as-built condition. The controller  130  controls the motion of the applicator  32  (as shown in  FIG. 2 ) as it moves across the surface structure by transferring motion control commands  137  to the actuator  36  (also shown in  FIG. 2 ). The commands  137  may impart three-dimensional motion to the actuator  36  so that the applicator  32  may move across curved surfaces that may include obstructions or other surface irregularities. The commands  137  may also impart motion to the actuator  36  so that the applicator  32  makes a single sweep across portions of the surface structure, so that the droplets forming an image on the surface structure are deposited in a single pass. Alternately, the motion imparted to the actuator  36  may include a plurality of repetitive sweeps across portions of the surface, in order to optically reinforce portions of the image having greater density. 
         [0030]      FIG. 7  is a partial cross-sectional view of an external portion  160  of an aircraft that will be used to describe a method of applying an image to an aircraft according to another embodiment of the disclosure. A primer layer  162  is applied to a supporting surface  164 , which is typically a structural portion of the aircraft, such as a fuselage panel, a wing panel, or other external surfaces of the aircraft. The primer layer  162  may be comprised of zinc chromate pigments that are added to carriers of several different resin types, such as epoxy, polyurethane, alkyd and others. A white opaque base layer  166  comprised of a resin type that is compatible with the primer layer  162  is then applied. A graphics layer  168  may then be applied to the white opaque base layer  166  to form image segments  170 , each comprised of a selected color and/or shape, which may be simultaneously applied to the white opaque base layer  166  using the ink-jet imaging process described in detail above. A transparent layer  172  may then be applied to the graphics layer  168  to protect the graphics layer  168  from the erosive effects of rain and water droplets encountered during flight, and to protect the image segments  170  of the graphics layer  168  from the prolonged effects of ultraviolet radiation. 
         [0031]    Those skilled in the art will also readily recognize that the foregoing embodiment may be applied to a wide variety of different locations on an aircraft. Referring now in particular to  FIG. 8 , a side elevation view of an aircraft  300  having at least one graphic image  314  according to the foregoing embodiment is shown. With the exception of the graphic image  314 , the aircraft  300  includes components and subsystems generally known in the pertinent art, and in the interest of brevity, will not be described further. The aircraft  300  generally includes one or more propulsion units  302  that are coupled to wing assemblies  304 , or alternately, to a fuselage  306  or even other portions of the aircraft  300 . Additionally, the aircraft  300  also includes a tail assembly  308  and a landing assembly  310  coupled to the fuselage  306 . The aircraft  300  further includes other systems and subsystems generally required for the proper operation of the aircraft  300 . For example, the aircraft  300  includes a flight control system  312  (not shown in  FIG. 8 ), as well as a plurality of other electrical, mechanical and electromechanical systems that cooperatively perform a variety of tasks necessary for the operation of the aircraft  300 . Accordingly, the aircraft  300  is generally representative of a commercial passenger aircraft, which may include, for example, the 737, 747, 757, 767 and 777 commercial passenger aircraft available from The Boeing Company of Chicago, Ill. Although the aircraft  300  shown in  FIG. 8  generally shows a commercial passenger aircraft, it is understood that the graphic image  314  according to the foregoing embodiment may also be applied to flight vehicles of other types. Examples of such flight vehicles may include manned or even unmanned military aircraft, rotary wing aircraft, or even ballistic flight vehicles, as illustrated more fully in various descriptive volumes, such as Jane&#39;s All The World&#39;s Aircraft, available from Jane&#39;s Information Group, Ltd. of Coulsdon, Surrey, UK. 
         [0032]    While preferred and alternate embodiments of the disclosure have been illustrated and described, as noted above, many changes can be made without departing from the spirit and scope of the disclosure. Accordingly, the scope of the disclosure is not limited by the disclosure of these preferred and alternate embodiments. Instead, the disclosure should be determined entirely by reference to the claims that follow.