Abstract:
A system for distributing signals between a first seat and a second seat of a platform. The system generally includes an elongated bus and a connector operable to provide a connection between the bus and the passenger seats. Signals can be transmitted between the bus and the passenger seats, via the connector, at any point along the power bus, thus eliminating the need to run separate connections between the signal source and each seat. The bus is connected to the connector by depressing the bus upon the connector. This system and method significantly reduces the amount of time, energy, and expense necessary to individually wire each passenger seat to receive signals, such as power and/or data.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of U.S. provisional application Ser. No. 60/556,823 filed Mar. 27, 2004, which is incorporated herein by reference.  
         [0002]     The following applications are also incorporated by reference herein: provisional application Ser. No. 60/556,826 filed on Mar. 27, 2004; provisional application Ser. No. 60/557,044 filed on Mar. 27, 2004; provisional application Ser. No. 60/556,747 filed on Mar. 27, 2004; provisional application Ser. No. 60/556,748, filed on Mar. 27, 2004; U.S. application Ser. No. 10/810,324 filed on Mar. 27, 2004; U.S. utility application Ser. No. 10/898,729 filed on Jul. 23, 2004; U.S. utility application Ser. No. 10/936,004 filed on Sep. 8, 2004; U.S. utility application Ser. No. 10/983,906 filed on Nov. 8, 2004; U.S. utility application Ser. No. 10/943,035 filed on Sep. 16, 2004; and U.S. utility application Ser. No. 10/921,553 filed on Aug. 19, 2004. 
     
    
     FIELD OF THE INVENTION  
       [0003]     The present invention relates to aircraft electronic systems. In particular, the present invention relates to a power strip that provides current to passenger seats in a mobile platform, such as an aircraft.  
       BACKGROUND OF THE INVENTION  
       [0004]     Commercial aircraft passengers are increasingly demanding in-flight entertainment (IFE) and electrical power outlets to operate various electronic devices, such as laptop computers, at their seats. To provide the passenger with such features, electrical power and data must be delivered to each seat. Conventionally, power and data are delivered to aircraft passenger seats via numerous cables that, during aircraft assembly, are laid out in position on the floor of the aircraft passenger cabin. A portion of the cables is positioned beneath a covering, such as the seat track cover, and a portion that includes connectors to the seats is left exposed to connect with the yet to be installed seat groups containing each passenger seat.  
         [0005]     During installation of the seat groups, the seat groups must be carried in over the exposed wires. Taking care to avoid the exposed, wires increases both the complexity of the operation and the amount of time required to install the seats. Once the seats are installed, installers must crawl along the floor of the aircraft to manually attach each wire to each seat group. This process is cumbersome and time consuming. Further, in order to change the configuration of the seats or to replace the seats, an installer must again crawl along the floor, disconnect the wiring from each group, and maneuver the seats around the exposed wiring. Still further, in order to change the position of the seat groups, the aircraft must be re-wired so that the wiring will reach the seats in their new positions. As would be expected, re-wiring an aircraft is a costly and time consuming process.  
         [0006]     In view of the foregoing, it is desirable to provide an improved device for delivering power to aircraft passenger seat groups that will eliminate the need to separately connect each seat group to an individual power or data cable and the need to re-wire the power cables when the seat configuration is changed.  
       SUMMARY OF THE INVENTION  
       [0007]     A power supply system operable to supply current and/or data to aircraft passenger seats in a mobile platform. The power supply system generally includes a power bus and a connector operable to provide a connection between the power bus and the passenger seats. Power and/or data can be transmitted between the power bus and the passenger seats, via the connector, at any point along the power bus, thus eliminating the need to run separate connections between the power and/or data source and each passenger seat.  
         [0008]     In one embodiment, the present invention provides for a system for distributing at least one of data and current between a first point and a second point of a platform. The system comprises an elongated bus and a connector located at at least one of the first point and the second point. The bus extends between the first point and the second point along an upper surface of a floor of the platform. The bus includes a housing that extends at least substantially an entire length of the bus and a conductor operable to conduct at least one of the data and current. The conductor is seated within the housing and extends at least substantially the entire length of the bus. The connector is located at at least one of the first point and the second point. The connector is operable to mate with the conductor to conduct at least one of the data and current between the conductor and the connector. The conductor is operable to mate with the connector at substantially any point along an entire length of the conductor.  
         [0009]     In another embodiment, the present invention provides for a system for distributing current in an aircraft passenger cabin to one or more passenger seats. The system includes a source for generating at least one of data and current, an elongated bus, and a connector. The bus extends between the source and the passenger seats along an upper surface of a floor of the passenger cabin. The bus includes a housing that extends at least substantially an entire length of the bus and a conductor that is operable to conduct the at least one of data and current. The conductor is seated within the housing and extends at least substantially the entire length of the bus. The connector is located at a seat leg of the passenger seat. The connector is operable to mate with the conductor to conduct current between the conductor and the connector. The conductor is operable to mate with the connector at substantially any point along an entire length of the conductor.  
         [0010]     In still another embodiment, the present invention provides for a method for distributing at least one of data and current between a first point and a second point of a platform. The method includes the step of positioning an elongated bus along an upper surface of a floor of the platform between the first point and the second point. The bus has a housing that extends at least substantially an entire length of the bus and a conductor operable to conduct at least one of data and current. The conductor is seated within the housing and extends at least substantially the entire length of the bus. The method further includes the step of connecting a connector located at at least one of the first point and the second point to the conductor at any point along a length of the bus to conduct at least one of the data and current between the first point and the second point.  
         [0011]     The features, functions, and advantages can be achieved independently in various embodiments of the present inventions or may be combined in yet other embodiments. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
         [0013]      FIG. 1  is a partially cut-away view of an aircraft showing the aircraft passenger cabin outfitted with the power supply system of the present invention;  
         [0014]      FIG. 2  is a perspective cross-sectional view taken along line  2 - 2  of  FIG. 1  showing a power bus strip contact device of the power bus system in a first position;  
         [0015]      FIG. 3  is a view similar to  FIG. 2  showing the power bus strip contact device;  
         [0016]      FIG. 4  is an expanded cross-sectional view of the power bus system of  FIGS. 2 and 3 ;  
         [0017]      FIG. 5  is a schematic view illustrating an exemplary wiring configuration of the present invention; and  
         [0018]      FIG. 6  is cross-sectional view of an alternative embodiment of the present invention.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0019]     The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.  
         [0020]     With initial reference to  FIG. 1 , a mobile platform in the form of a passenger aircraft equipped with a power distribution system according to the present invention is illustrated at reference numeral  10 . It will be appreciated, however, that the present invention is not limited to use only in commercial aircraft and can be implemented in any form of mobile platform, such as a ship, train, bus, motor craft, etc.  
         [0021]     The aircraft  10  generally includes a fuselage  12 , wings  14 , and a tail fin  16 . The fuselage  12  includes a passenger cabin  18  having a floor  20 . At the floor  20  are numerous passenger seats  22 . Two or more passenger seats  22  are grouped together as a seat group  24 . One or more seat tracks  26  extend along the floor  20  to secure the seat groups  24  into position. A power bus system  28  for delivering power to the seats  22  extends along side of, or closely adjacent to, one or more of the seat tracks  26 . The power bus system  28  connects to a power source  30 . The seat tracks  26  and the power bus system  28  are typically covered by a seat track cover  32 .  
         [0022]     With continued reference to  FIG. 1  and additional reference to  FIG. 2 , each seat group  24  includes a frame  34 . The frame  34  includes legs  40 . The legs  40  provide support to the different passenger seats  22 . The legs  40  include an upper portion  42  and a lower portion  44 . The upper portion  42  mates with or can be integrated with the seats  22 . The lower portion  44  includes a fastening surface  46 . The fastening surface  46  can be any conventional fastening device capable of securing the seat group  24  to the seat track  26 . For example, the fastening surface  46  can include a tab  48  for cooperating with the seat track  26 , as described in further detail below. The tab  48  can be, for example, round, square, or rectangular, to be securely received by the seat track  26 .  
         [0023]     The seat track  26  has a base portion  50 , a floor support  52 , and a seat engagement portion  54 . The base portion  50  includes one or more extensions  56  to support the seat track  26  on a fuselage floor beam  58 . The floor support  52  includes one or more protrusions  60  that protrude from the seat engagement portion  54 . The protrusions  60  provide support to the floor  20  in the area proximate to the seat track  26 . The seat engagement portion  54  includes two arms  62  for cooperating with and securing the legs  40 .  
         [0024]     With additional reference to  FIG. 3 , the seat track cover  32  is an elongated strip for covering the seat track  26  and the power bus system  28 . The seat track cover  32  is somewhat semicircular in shape with a first sidewall  64 , a second sidewall  66 , and a top portion  68 . The first sidewall  64  and the second sidewall  66  extend from the top portion  68  generally at an angle, such that when the cover  32  is placed on a flat surface, such as the floor  20  or carpeting of the floor  20 , the cover  32  partially defines a cavity  70  between the flat surface and the cover  32 .  
         [0025]     With continued reference to  FIGS. 1 through 3  and additional reference to  FIG. 4 , the power bus system  28  generally includes a power bus strip  72  and a power bus strip contact device  74 . The power bus strip  72  generally includes an elongated housing  76  having one or more open receptacles  78 . The receptacles  78  extend the entire length of the power bus strip  72 . The receptacles  78  include a conductor  80 , such as copper. The conductor  80  extends the entire length of the power bus strip  72  and/or the entire length of the receptacles  78 . The receptacles  78  can be numerous different shapes and sizes and can include a locking detail  82 . The housing  76  can be made of numerous conventional materials, but is typically made of a resilient material, such as rubber. The receptacles  78  can be formed within the housing  76  itself or can be formed as a separate component that is inserted within the housing  76 .  
         [0026]     As illustrated, the housing  76  includes a first conductor  80 A in communication with the power source  30  to carry power from the power source  30 , a second conductor  80 B that is in communication with the power source to return power to the power source  30 , and a third conductor  80 C to ground the power bus  28  by connecting to a suitable ground surface at any point along the strip  72 . The power source  30  can be a dedicated battery for supplying power to the passenger seats  22  or can be connected to the general aircraft power supply. The power source  30  can include electrical contacts (not shown) that make electrical contact with the conductor  80 A to transfer electricity to the conductor  80 A. The number of conductors  80  and their function may vary depending on the application. To make the conductors  80  more flexible for transportation and installation, the conductors  80  can be at least partially slit across at least a portion of their length.  
         [0027]     The power bus contact device  74  includes a base  84  and one or more contacts  86 . In some applications the base  84  can be a generally rigid, rectangular foundation upon which the contacts  86  are rigidly mounted. The contacts  86  can be directly mounted to the base  84  or can be mounted upon spring supports  88  to bias the contacts  86  such that the contacts  86  extend outward from the base  84 . The contacts  86  can be of any suitable shape or size and of any suitable material, such as copper. To cooperate with the receptacles  78 , the contacts  86  are typically shaped and sized in a manner that mirrors the shape and size of the receptacles  78 . For example, the contacts  86 , as illustrated in  FIGS. 2 through 4 , have a round head  90  supported by a stem  92 . The shape of the head  90  approximates the interior shape of the receptacles  78  and permits the locking detail  82  to lock around the head  90 . Other shapes and configurations that can be used by the receptacles  78  and the contacts  86  include, but are not limited to, a Christmas Tree fastening system, an over-center fastening system, and a pitchfork fastening system. As illustrated, the contacts  86  include a first contact  86 A, a second contact  86 B, and a third contact  86 C. However, the number of contacts and their function can vary depending on the application.  
         [0028]     The power bus contact device  74  can be separate from the seat leg  40  or can be secured to the seat leg  40  via a suitable fastening device, such as a hinged fastening device  94 . The seat leg  40  can be manufactured to include the power bus contact device  74 . Alternatively, conventional seat legs  40  without the contact device  74  can be retrofitted to include the contact device  74  secured to the leg  40 . The hinged fastening device  94  permits the power bus contact device  74  to pivot between a retracted position in which the contact device  74  is vertical and parallel to the seat leg  40  ( FIG. 2 ), and an extended position in which the power bus contact device  74  extends from the seat leg  40  at approximately a right angle to a vertical portion of the leg  40  ( FIG. 3 ). In addition to the hinged fastening device  94 , any other suitable fastening device can be used, such as a rotational fastening device (not shown) in which the power bus contact device  74  rotates from the seat leg  40  in the same plane as the floor  20  as it is moved from the retracted position to the extended position ( FIG. 3 ).  
         [0029]     With additional reference to  FIG. 5 , one or more wires  112  extend from the contacts  86  through both the base  84  and the seat legs  40  to the seats  22 . As illustrated, a first wire  112 A is in electrical connection with the first contact  86 A, a second wire  112 B is in electrical contact with the second contact  86 B, and a third wire  112 C is in electrical contact with the third contact  86 C. In addition to this configuration, the third wire  112 C can extend down the seat leg  40 ′ opposite the seat leg  40  near the power bus  28  to ground the seat group  24  and the power bus  28  at the seat track  26 ′.  
         [0030]     The cooperation of the above components and their operation will now be described in detail. The seat track  26  is generally positioned just beneath or at the surface of the floor  20  and extends the length of, or at least a portion of the length of, the passenger cabin  18 . Portions of the floor  20  are removed just above the seat track  26  to permit access to the seat track from the passenger cabin  18 . The aircraft can include any number of seat tracks  26  depending on the application. In some applications, two seat tracks  26  are provided to support each seat group  24  at the floor  20 .  
         [0031]     The seat track  26  is typically held in position by securing the extensions  56  to the floor beam  58  of the fuselage  12 . The extensions  56  are secured to the floor beam  58  in any suitable manner, such as using an adhesive or a fastener, such as a bolt  96  extending through the extensions  56 , at numerous positions along the length of the seat track  26 . With the seat track  26  secured into position below the floor  20 , the floor support  52  provides support to the portions of the floor proximate to the seat track  26 .  
         [0032]     To further secure the seat tracks  26  into position, additional fasteners can be used along the length of the seat track  26 , such as a flush mounted screw  98 , to secure the protrusions  60  of the floor support  52  to the floor  20 . Specifically, an insert  100  can be positioned within the floor  20  to receive the flush mounted screw  98 , which further extends through the protrusions  60 . A clip-nut  102  is typically used to secure the flush mounted screw  98  to the protrusions  60 . The clip-nut  102  includes a top portion  106  and a bottom portion  108 . The top portion  106  includes an aperture for receiving the flush mounted screw  98  and the bottom portion  108  includes a conventional lock-nut  110  that is held captive within the bottom portion  108 . The clip-nut wraps around the protrusion  60  such that the top portion  106  is at an upper surface of the protrusion  60  and the bottom portion  108  is at a lower surface of the protrusion  60 . To secure the protrusion  60  to the floor  20 , the flush mounted screw  98  is inserted through the insert  100 , through the top portion  106  of the clip nut  102 , through the protrusion  60 , and through the bottom portion  108  where it cooperates with the lock-nut  110  to hold the flush mounted screw  98  into position to fasten the floor  20  to the protrusions  60  of the floor support  52 .  
         [0033]     With the seat tracks  26  secured in position, the seat groups  24  containing the passenger seats  22  are be installed. The seat groups  24  are positioned above the seat tracks  26  such that the legs  40  of each seat group are aligned with the seat tracks  26 . Generally, the fastening tab  48  of the seat legs  40  is, at its widest point, wider than the distance between the arms  62  of the seat engagement portion  54  of the seat track. However, at various apertures along the length of the seat track  26 , the distance between the arms  62  increases to permit passage the tab  48 . It is at these regions that the fastening tab  48  is inserted past the arms  62  to within the seat engagement portion  54 . The seat group  24  is then moved along the seat track  26  such that the tab  48  is moved to a point in the seat track  26  where the distance between the arms  62  is less than the width of the tab  48  to lock the tab  48 , and thus the seat group  24 , to the seat track  26 . To insure that the tab  48  does not return to the area of the seat track  26  where the distance between the arms  62  is widened, the seat leg  40  is be secured into position along the seat track  26  in any conventional manner, such as by a bolt.  
         [0034]     The power bus contact device  74  is positioned at or proximate to the leg  40  either before or after the legs  40  of the seat groups  24  are secured to the seat tracks  26 . If the seat leg  40  is manufactured to include the power bus contact device  74 , the device  74  can be rotated, for example, via the hinged fastening device  94  to an extended position in which the device  74  extends from the leg  40  approximately parallel to the floor  20  and approximately perpendicular to the leg  40 . In this extended position the device  74  places the contacts  86  in a position in which they are operable to make electrical contact with the power bus strip  72 . If the device  74  is not secured to the leg  40 , the passenger cabin  18  can be retrofitted with the device  74  by manually placing the device  74  at or proximate to the leg  40 . The device  74  can be placed directly on the floor  20 , or carpeting covering the floor, using a suitable adhesive or a hook and loop fastening system, such as Velcro®, in which the hook portion is provided on an undersurface of the power bus contact device  74  and the loop portion is provided by the carpeting itself.  
         [0035]     The power bus strip  72  is extended across numerous contact devices  74  of different seat groups  24 . Specifically, the power bus strip  72  is positioned atop the contact device  86  such that the conductor  80 A connects to the contact  86 A to transfer power to the wire  112 A, the conductor  80 B connects to the contact  86 B and the wire  112 B to provide a power return to the power supply  30 , and the conductor  80 C connects to the contact  86 C and the wire  112 C to provide a ground. As seen in  FIG. 5 , the energized wire  112 A is used to transfer power to an outlet  118 , or other electrical device(s) of the seat group  24  with the wire  112 B serving as the return and the wire  112 C serving as the ground to the frame  34 .  
         [0036]     Finally, the seat track cover  32  is inserted over the seat track  26  and the power bus  28 . To accommodate the seat legs  40 , a section of the top portion  68  of the cover  32  is removed. The seat track cover  32  is secured to the floor  20  using any suitable adhesive or mechanical fastening device.  
         [0037]      FIG. 6  illustrates an additional embodiment of the power bus system of the present invention at  200 . Because this embodiment includes numerous elements similar to the elements described above, the same reference numbers are used to describe these like elements. Further, the above description applies to these like elements and the operation of the embodiment of  FIG. 6   
         [0038]     The power bus system  200  generally includes a power bus housing strip  202  and one or more power bus conductor strips  204 . The power bus housing strip  202  generally includes a housing strip body  206  and a housing strip extension flap  208 . The housing strip  202  is generally an elongated strip that extends approximately the length of the passenger cabin  18 , or the length of any desired “zone” of the passenger cabin  18 . The housing strip body  206  includes a cavity  210  and a slit or inlet  212  that permits access to the cavity  210 . The extension flap  208  extends from the body  206  and generally includes a cover  214  and a clip  216  extending from an undersurface of the cover  214 . The clip  216  is configured to cooperate with the fastening surface  46  of the seat track  26  and secure the cover  214  to the seat track  26 . The body  206  and flap  208  can be made of a flexible material, such as a polymeric material to allow the flap  208  to snap within the seat track  26 .  
         [0039]     The power bus conductor strip  204  is typically located within the cavity  210 . The conductor  204  includes an open-ended aperture  218  and a locking detail  220 . The conductor  204  can be made of a conductive material, such as copper. As illustrated, the housing  202  includes a first conductor  204 A that is in contact with the power supply  30  to conduct power through the housing  202 , a second conductor  204 B that serves as a power return back to the power supply  30 , and a third conductor  204 C that is in communication with any suitable ground surface to ground the power bus system  200 . When the power bus system  200  is fully assembled, as in  FIG. 6 , the first conductor  204 A is in contact with the wire  112 A to direct power through the wire  112 A, the second conductor  204 B is in contact with the wire  112 B to receive power returned through the wire  112 B, and the third conductor  204 C is in contact with the wire  112 C to ground the seat group  24  and the power bus system  200 . Contact between the conductors  204  and the wires  112  is provided by connectors  222 . To make the conductor  204  more flexible for transportation and installation, the conductor  204  can be at least partially slit across at least a portion of its length. In some embodiments the connectors  222  can rigidly extend from the seat leg  40 .  
         [0040]     The power bus system  200  is particularly useful for retrofitting an aircraft passenger cabin  18  with a power supply system, however, the power bus system  200  may also be used in the assembly of a new aircraft before or after the passenger seats  22  are installed. When used as a retrofit device, the existing seat track cover (not shown) of the aircraft is removed to expose the seat track  26 . The clip  216  is inserted within the seat track  26  such that the cover  214  is secured at the top of the seat track  26  and the power bus housing strip  202  is secured along side of the seat track  26 . Portions of the cover  214  are removed at the seat legs  40  to permit the power bus system  200  to extend past the seat legs  200 . The plugs are then inserted within the conductors  204 A,  204 B, and  204 C, to provide contact with the wires  112 A,  112 B, and  112 C respectively.  
         [0041]     It must be noted that while the power bus system  28  and power bus system  200  are described as distributing power to the passenger seats  22 , the systems  28 / 200  can also be used to distribute data to the passenger seats  22 . For example, data distribution can be performed using conventional communication over power line systems.  
         [0042]     It must also be noted that the passenger cabin  18  can be outfitted with multiple power bus systems  28 / 200  at each seat group  24 . The multiple power bus system(s)  28 / 200  can be provided at the same seat track  26  or different seat tracks  26 . The use of multiple power bus systems  28 / 200  is useful to provide separate power bus systems for both power and data. Further, a first power bus system  28 / 200  at the seat track  26  can be used for current delivery and a second power bus system  28 / 200  can be used as a current return. Still further, the use of a second power bus system  28 / 200  can be used to supply additional current to the seat groups  24 .  
         [0043]     The power bus systems  28 / 200  can also include a data only optical strip (not shown) housed within either the housing  76  or the body  206  of the power bus systems  28 / 200  respectively. The optical strip can be any conventional optical data line. For example, the optical strip can be made by co-extruding opaque plastic over clear plastic to make a light guide. High-bandwidth data can be sent to the seat groups  24  using conventional “lightguide” technology, or any other short-range fiber optic technology. This high-bandwidth data is received by each seat group  24  and each seat  22  by a conventional high-bandwidth receiver or connector.  
         [0044]     The power bus systems  28 / 200  can further include a data strip (not shown) that carries both optical data and electrical current. For example, a clear plastic with sufficiently high dielectric to insulate a power conductor, such as polyethylene, can be co-extruded around one or more of the conductors  80 / 204  with a clear plastic interior and an opaque plastic exterior. Data can be transmitted through the plastic portion using, for example, conventional “lightguide” technology or any other short-range fiber optic technology, and electrical current can be conducted through the conductors  80 / 204 . By adding a conventional optical tap (not shown) to either the contacts  86  or connectors  222  of the power bus systems  28 / 200  respectively, a single conductor  80 / 204  can be used to transmit both power and optical data.  
         [0045]     In another embodiment of the power bus system  200 , the connectors  222  are mounted on the floor  20  of the aircraft  10  such that the connectors  222  face upward and away from the floor  20 . Further, the inlet  212  of the cavity  210  extends downward toward the floor  20 . In this configuration, the connection between the connectors  222  and the cavity  210  is made when the body  206  of the power bus housing  202  is laid along the passenger cabin floor  20 . This embodiment eliminates the need to manually insert each connector  222  within the cavity  210 .  
         [0046]     In still another embodiment, the power bus systems  28 / 200  are arranged such that the power bus strip  72  or the housing strip body  206  extend between the seat legs  40  at or within the seat tracks  26 . For example, the contacts  86  of the power bus system  28  and the connectors  222  are positioned at both ends of the legs  40  in the power bus systems  28 / 200  respectively. The power bus strip  72  and the body  206  extend between the legs and between the seat groups  24  so that the energized conductors  80  mate with the contacts  86  and the conductors  204  mate with the connectors  222  to provide power and/or data to the seats  22 . By only running the power bus strip  72  and the housing strip body  206  between the seat legs  40 , the continuous lump besides the seat tracks  26  created by running the power bus strip  72  or the housing strip body  206  continuously along the floor  20  is eliminated.  
         [0047]     The present invention, while being especially well suited and advantageous for use on mobile platforms, could also just as easily be implemented in a fixed structure having a plurality of items requiring electrical power and/or data. Such an implement would also significantly reduce the complexity of the cabling and connectors needed to supply power and/or data lines to the different items.  
         [0048]     While various preferred embodiments have been described, those skilled in the art will recognize modifications or variations which might be made without departing from the inventive concept. The examples illustrate the invention and are not intended to limit it. Therefore, the description and claims should be interpreted liberally with only such limitation as is necessary in view of the pertinent prior art.