Patent Document

CROSS REFERENCES TO RELATED APPLICATIONS 
     This application is a continuation-in-part of application Ser. No. 10/965,133 filed on Oct. 14, 2004, entitled “Flexible Pixel String Hardware and Method”, which is pending. 
     This application claims priority from the earlier filed U.S. Provisional Application No. 60/926,706 filed Apr. 27, 2007, entitled “Flexible Pixel Assemblies for Mounting on Irregular Surfaces”, and is hereby incorporated into this application by reference as if fully set forth herein. 
     This application is related to patent application Ser. No. 10/965,127 filed on Oct. 14, 2004, entitled “Flexible Pixel String Software and Method”, which is pending. 
     This application is also related to U.S. utility patent application entitled “Flexible Pixel Element and Signal Distribution Means”, application number to be assigned, filed concurrently herewith, a copy of which is attached and the disclosure of which is incorporated by reference as if fully set forth herein. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention teaches a discrete flexible pixel element for use in flexible pixel strings and, more particularly, a fabrication method and means for hermetic sealing of discrete flexible pixel elements. 
     Flexible pixel elements may be used in large scale, direct view electronic display devices and signage mounted on large area and/or irregular surfaces, such as the interior or exterior of buildings, where the intent is to complement the surface architecture of the building by conforming to the building surfaces. A particular problem arises with electronic display devices used in outdoor or exterior displays such as signs since delicate electronic components in such displays are exposed to the detrimental effects of environment, rough handling and inclement weather and are therefore vulnerable to failure. The discrete flexible pixel element, fabrication method and means for hermetic sealing of the present invention precludes failure of electronic components due to the detrimental effects of environment, thereby enabling efficient, economical production of large scale, direct view electronic display devices, signage and lighting effects for outdoor use. 
     2. Description of the Prior Art 
     Electronic display devices and signage are known in the art. An electronic display device typically comprises a display board that produces visual images by means of a grid of small light emitting elements, such as incandescent bulbs, LEDs, or the like; data handling and control means for managing transfer of digital image data for display as visual output images, and means for converting digital image data into visual image data and display control signals to drive the light emitting elements, or pixels, to thereby produce visual output images on the electronic display devices for viewing. 
     The sophistication of visual images that can be displayed on electronic display devices is generally dependent on the capabilities of the light emitting elements, or pixels, used to produce visual images. Light emitting display technology has become increasingly more advanced in the art, progressing from monochrome incandescent and LED devices to video quality components capable of exhibiting near continuous tone visual output, complex animations and live video streams. Improvements in light emitting display technology, including light emitting elements, have in turn enabled the manufacture of electronic display devices that are increasingly large in scale and more powerful in terms of the complexity and sophistication of the visual output images that can be displayed. 
     Electronic display devices and signage sited in outdoor locations, such as on the exterior surfaces of buildings, are also known in the art. Outdoor electronic display devices and signage are commonly sited near public venues where the visual output images they exhibit may be viewed simultaneously by large numbers of people in groups. Outdoor electronic display devices provide a valuable service to the public since they can provide timely or time-critical information, such as stock and commodity prices, traffic and weather conditions, hazard alerts, and other important information. One popular type of outdoor electronic display device is a large scale video for advertising displays and signage where commercial messages are broadly and effectively exhibited for public viewing. 
     An inherent problem in the design and manufacture of large scale electronic display devices for outdoor use is the need to protect delicate and vulnerable internal electronic components from failure due to the detrimental effects of environment. This problem is exacerbated by the increasing sophistication of light emitting elements and their collateral support electronics, such as the electronic drivers for the light emitting elements. In the early art, incandescent bulbs served as light emitting elements. Incandescent bulbs are comparatively inexpensive to use, robust in operation and easy to replace; moreover, they require few and comparatively inexpensive collateral support electronics and power and signal conductors. More advanced light emitting elements or pixels, such as LEDs and LCDs, are more expensive to use and replace. In addition, they require more numerous and more expensive collateral support electronics, including pixel element drivers, data buffers, control signal handlers, over-voltage and transient protection circuits, to name a few. Furthermore, advanced light emitting elements and collateral support electronics are comparatively much more delicate and easily damaged by electrostatic shock, thermal shock, mechanical shock, moisture and humidity, and various other detrimental environmental conditions. Advanced light emitting elements and collateral support electronics also require more sophisticated means of mounting and electrical connection, such as surface mounted printed circuit boards (PCBs), as well as more sophisticated means of supplying operating power, digital image data and display control signals, which means greatly increase the number of signal paths and conductors needed to service components and thereby greatly increase the number of connection points and potential points of failure. Therefore, the use of advanced light emitting elements, while presenting advantages in terms of the sophistication of visual output images that can be displayed, also presents a vulnerable design architecture with many potential points of failure. 
     In the prior art, light emitting elements are collectively sealed within enclosures to protect them from the outside environment. Not only does this add to the cost of producing already expensive large scale outdoor electronic displays and signage, but such enclosures are generally effective only for conventional, rectilinear or planar displays mounted on flat surfaces. Producing collective enclosures that conform to irregular shaped surfaces can be a complex and costly undertaking. Moreover, a collective enclosure typically embodies a single-point failure mode, wherein any failure of the collective enclosure exposes all the light emitting elements, collateral support electronics and connection points contained therein to potential failure. Finally, collective enclosures are subject to overheating from both internal and external sources, including component power dissipation and solar radiation. 
     A solution to some of these problems is taught in co-pending U.S. utility patent application entitled “Flexible Pixel Element and Signal Distribution Means”, application number to be assigned, filed concurrently herewith, a copy of which is attached and the disclosure of which is incorporated by reference as if fully set forth herein. A portion of that teaching is the use of a plurality of discrete flexible pixel elements that can be interchangeably connected in series by means of flexible cables to produce flexible pixel strings that are conformable to irregular shapes and surfaces. 
     The present invention further discloses means and methods that are operative and efficacious in manufacturing discrete flexible pixel elements, including a fabrication method and means for encapsulating pixel element electronics, such as light emitting elements and collateral support electronics, and encasing the encapsulated pixel element electronics in an external top encasement cover in order to produce a unitary, hermetically sealed, self-contained module that is protected from the detrimental effects of the environment. The present invention also discloses means for connecting power and signal cables to a plurality of discrete flexible pixel elements in series connection, whereby electrical conductors and contacts within power and signal cables are similarly protected. 
     In summation, the prior art is generally dependent on conventional means, such as collective enclosures, to protect pixel element electronics used in electronic display devices sited outdoors from preventable failure and damage. Conventional collective enclosures are not well suited for protecting electronic display devices that conform to irregular shapes and surfaces since they are difficult and expensive to fabricate. Furthermore, they embody a single point failure mode which exposes all internal components and connections to potential failure, as well as being subject to overheating. As a result, production of such enclosures is cost prohibitive, while outcomes are often inelegant and failure prone. A novel approach to address the aforesaid deficiencies of the prior art is needed to continue to satisfy public demand and thereby ensure continuing development of the art. 
     SUMMARY OF THE INVENTION 
     The general purpose of the present invention is to protect delicate and vulnerable pixel element electronics used in discrete flexible pixel elements from failure and damage due to detrimental effects of environment. More specifically, the present invention discloses a fabrication method and means for hermetic sealing of pixel element electronics embodied within discrete flexible pixel elements. The fabrication method comprises an encapsulation means and an external casement means. In addition, the fabrication method embodies connection means for connecting power and signal cables conjoining a plurality of discrete flexible pixel elements in series-connection, wherein electrical conductors and terminal contacts embodied within said power and signal cables are similarly protected. 
     The encapsulation means may include the use of a potting resin or gel that encapsulates said pixel element electronics and hardens on exposure to the atmosphere, heat, or a reactive agent such as a hardener. Alternatively, the encapsulation means may include the use of a ductile foam or malleable solid potting material having similar protective properties in application and which harden by similar processes to achieve similar results. 
     External casement means may embody a formed top encasement cover of plastic or similar material, wherein the top encasement cover has an internal cavity configured to receive encapsulated pixel element electronics in assembly. The formed top encasement cover may be transparent to pass light from light emitting elements or may have holes therein enabling the light emitting elements to protrude therefrom in order to pass light directly. 
     Alternatively, external casement means may embody a formed top encasement cover which has an internal cavity configured to receive pixel element electronics not yet encapsulated and which serves as a potting shell enabling pixel element electronics positioned therein to be encapsulated in situ. 
     In another alternative embodiment, external casement means may embody a formed top encasement cover which is formed around encapsulated pixel element electronics in a fused close fit therewith, such as by plastic forming or by an injection molding means. 
     In yet another alternative embodiment, the formed top encasement cover may have some corresponding fitting features adaptively to receive a barrier sealant means which may embody a ductile barrier sealant such as caulk or a malleable barrier sealant such as sealing lace or cord or a solid barrier sealant such as a sealing gasket or O-ring, wherein said corresponding fitting features engage the barrier sealant in a close fit therewith to establish a sealed barrier to atmosphere. 
     Connection means for connecting power and signal cables conjoining a plurality of discrete flexible pixel elements in series connection may embody formed cable connectors of plastic or similar material that house and mechanically support electrical conductors and terminal contacts, wherein said formed cable connectors and terminal contacts have corresponding fitting features which enable them to conjoin in a close mechanical fit to thereby establish series connections between a plurality of discrete flexible pixel elements, and wherein said close mechanical fit establishes a sealed barrier to the atmosphere. 
     According to one embodiment of the present invention, there is provided a fabrication method for hermetic sealing of pixel element electronics embodied within discrete flexible pixel elements which comprises an encapsulation means, an external casement means and a connection means for connecting power and signal cables. 
     According to another embodiment of the present invention, there is provided an encapsulation means that includes the use of a formed potting shell which has fitting features for receiving a pixel element electronics assembly, further presenting cavities for receiving potting material, thereby enabling the encapsulation of said pixel element electronics assembly through the introduction of the potting material, and further having fitting features for receiving components of said external casement means in a close fit therewith. 
     According to still another embodiment of the present invention, there is provided a potting resin or gel that encapsulates a pixel element electronics assembly which potting resin or gel hardens by exposure to the atmosphere or heat or by a reactive agent such as a hardener. The potting resin or gel is selected or formulated for optimal performance characteristics and properties efficacious for encapsulating pixel element electronics of discrete flexible pixel elements and protecting them from the detrimental effects of the environment. 
     According to yet another embodiment of the present invention, there is provided an external casement means which embodies a formed top encasement cover and formed bottom plate of plastic or similar material, wherein the formed top encasement cover has an internal cavity configured to receive the encapsulated pixel element electronics assembly and which further has fitting features to receive said formed bottom plate in close fit therewith, the formed top encasement cover having through holes therein to enable the light emitting elements to protrude therefrom. 
     According to still another embodiment of the present invention, there is provided connection means for connecting power and signal cables that embody formed connector headers of plastic or similar material which house and mechanically support electrical conductors and terminal contacts and which have fitting features enabling them to conjoin in a close mechanical fit, thereby establishing a sealed barrier to the environment. 
     A significant aspect and feature of the present invention is that the fabrication means which enables the hermetic sealing of delicate and vulnerable pixel element electronics contained within discrete flexible pixel elements in order to protect them from failure and damage due to the detrimental effects of the environment. 
     Another significant aspect and feature of the present invention is that the hermetically sealed discrete flexible pixel elements can better withstand the rough handling and mechanical shock during the shipping and assembly of electronic display devices and during required service and replacement thereof upon failure. 
     Yet another significant aspect and feature of the present invention is that the hermetically sealed discrete flexible pixel elements can better withstand inclement weather, moisture and humidity, electrostatic shock, thermal shock, and other detrimental effects of the environment, therefore they are better adapted for application in outdoor sites. 
     Still another significant aspect and feature of the present invention is that the hermetically sealed cable connectors and conductors supplying said pixel element electronics will protect the terminal connections from possible failure and damage due to rough handling and the detrimental effects of the environment. 
     A further significant aspect and feature of the present invention is that the hermetically sealed flexible discrete pixel elements do not require expensive collective enclosures thereby preventing individual failure of discrete flexible pixel elements and pixel element electronics embodied therein due to single-point failure of the enclosure. 
     A further significant aspect and feature of the present invention is that the hermetically sealed discrete flexible pixel elements will ensure greater longevity of pixel element electronics embodied therein and are more easily replaced upon failure. 
     A final significant aspect and feature of the present invention is that the fabrication method and means for hermetic sealing of discrete flexible pixel elements provide a robust design architecture, an improved cost-benefit in the design, manufacture and maintenance of large scale, direct view electronic display devices and signage for outdoor applications. 
     Having thus described embodiments of the present invention and setting forth significant aspects and features of the present invention, it is the principal object of the present invention to provide a discrete flexible pixel element that is hermetically sealed from the environment and embodied as a unitary, self-contained, replaceable module for efficient, economical production of large scale, free-form electronic displays, signs and lighting effects for outdoor applications. The present invention teaches a fabrication method for producing hermetically sealed discrete flexible pixel elements including means for encapsulating pixel element electronics, exterior casement means, and cable connector means. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other objects of the present invention and many of the attendant advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, in which like reference numerals designate like parts throughout the figures thereof and wherein: 
         FIG. 1  is an isometric view showing a hermetically sealed discrete flexible pixel element of the present invention embodying a unitary, self-contained, replaceable module; 
         FIG. 2  is a cross section side view of a pixel element electronics assembly attached to a potting shell with fasteners; 
         FIGS. 3A and 3B  are isometric top and bottom views of a pixel element electronics assembly and potting shell in assembly with potting material being applied to upper and lower cavities in the potting shell; 
         FIG. 4  is an isometric assembly view of a discrete flexible pixel element showing a pixel element electronics assembly and potting shell in assembly, top cover and bottom gasket; 
         FIG. 5  is an assembled view of the components of  FIG. 4 ; 
         FIG. 6A  is a cross section side view of a plurality of discrete flexible pixel elements of the present invention in series connection with pixel element electronics assemblies therein fully encapsulated by potting material and attached to a planar mounting surface; 
         FIG. 6B  is similar to  FIG. 6A  but with the plurality of discrete flexible pixel elements attached to a non-planar or irregular surface; and, 
         FIG. 7  is a cross section side view of input and output cable connectors of discrete flexible pixel elements showing corresponding mating components and applied potting material. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  is an isometric view of a preferred embodiment of discrete flexible pixel element  10  of the present invention. The flexible pixel element  10  embodies a printed circuit board assembly (not shown) on which various surface mounted electrical components are soldered or mechanically fastened to conductor pads by operative electrical connection including a plurality of light emitting elements  13 , top encasement cover  30 , input connector  14 , output connector  16 , and flexible cables  18  embodying in assembly a unitary, self-contained, replaceable module. The light emitting elements  13 , or pixels, are illuminated when energized by on-board pixel element drivers (not shown) to produce a visual output in the form of emitted light. In a preferred embodiment, the light emitting elements  13  comprise a plurality of red, green and blue (RGB) colored LEDs. 
       FIG. 2  is a cross section side view of potting assembly  20 , a top encasement cover  30 , and a bottom gasket  32 . Printed circuit board assembly  11  supports a plurality of surface mounted pixel element electronics  15 , including light emitting elements  13  and pixel element drivers  15   a , in addition to other collateral support electronics, such as resistors and capacitors (not shown), soldered or mechanically fastened to conductor pads by operative electrical connection. The printed circuit board assembly  11  is fastened to a potting shell  22  by mechanical fasteners  29  of sufficient length for attaching said discrete flexible pixel element  10  in finished assembly to a mounting surface or back-plate  36  (see  FIGS. 6A and 6B ) of an electronic display device. Potting shell  22  is a formed housing of plastic or similar material that presents an upper cavity  24  and lower cavity  26  for receiving potting material. Upper cavity  24  has an upper cavity wall  24   a  of sufficient height to enable said potting material to fill the upper cavity  24  to a cavity limit indicated by reference numeral  24   b , thereby to fully cover a proximal lower portion of light emitting elements  13 . The electrical conductors  13   a  of the light emitting elements  13 , as well as the pixel element electronics  15 , are completely encapsulated. However, the distal upper portions of the light emitting elements  13  are not encapsulated thus providing an unobstructed transmission of light from the flexible pixel element  10 . 
     A lower cavity wall  26   a  has a sufficient height to enable potting material to fill the lower cavity  26  to a limit, indicated by reference numeral  26   b , which is sufficient to fully cover flexible cable headers  17 ,  19  and a proximal portion of flexible cables  18 , thereby fully encapsulating flexible cable headers  17 ,  19 , as well as the underside of the printed circuit board assembly  11  and further providing strain relief to flexible cables  18 . 
       FIGS. 3A and 3B  are top and bottom isometric views of potting assembly  20 . A potting material  28  is applied in sufficient quantity (partially shown) to fill the upper cavity  24  of potting shell  22  to the upper limit of the interior cavity wall  24   a  without overflow and to fill the lower cavity  26  of potting shell  22  to the upper limit of interior cavity wall  26   a  without overflow. Potting material  28  may be any conventional potting material, such as epoxy or polyurethane potting compounds, having optimal performance characteristics and properties efficacious for encapsulating pixel element electronics  15  of discrete flexible pixel assembly  10 , to-whit:
         (1) potting material  28  is a thermally, chemically and electrically inert material that, when hardened, protects pixel element electronics  15  from moisture, humidity, solar radiation, atmospheric pressure changes, vacuum, corrosive chemicals, electrical shock, thermal shock, mechanical shock, and other detrimental environmental effects;   (2) potting material  28  is a viscous material with optimal flow properties for application in predetermined quantities for filling upper cavity  24  and lower cavity  26  of potting shell  22 , either by manual application or by machine application, such as by a meter-mix-dispense (MMD) method, at optimal speed without overflow;   (3) potting material  28  is a sublimating material with optimal state change characteristics to enable rapid hardening, either by self-sublimation through exposure to atmosphere or by use of a hardening agent;   (4) potting material  28  is an adhesive material with optimal adhesion characteristics to fully bond with interior cavity walls  24   a ,  26   a  of potting shell  22  without requiring separate adhesion means;   (5) potting material  28  is a volumetrically stable material that exhibits minimum shrinkage after hardening;   (6) potting material  28  is a thermally conductive material with exothermic characteristics for transmitting heat generated by pixel element electronics  15  to the environment at a rate sufficient to prevent thermal overload;   (7) potting material  28  is a strong material when hardened and exhibits optimal compressive strength to enable mounting discrete flexible pixel assemblies by mechanical fasteners  29  without damage; and,   (8) potting material  28  is a temperature resistant material when hardened and exhibits insensitivity to ambient temperature within an operating range optimal for use in outdoor applications of discrete flexible pixel elements  10  in electronic display devices.
 
Once applied, potting material  28  is allowed to harden in a state change sublimation by exposure to the atmosphere or through the use of a hardening agent, thereby completing encapsulation of pixel element electronics  15  within potting assembly  20 .
       

     Those skilled in the art will apprehend that the foregoing performance characteristics and properties of potting material  28  for use in discrete flexible pixel elements  10  involves various design choices and tradeoffs in the selection of optimal characteristics thereof. Accordingly, reference to the performance characteristics and properties of potting material  28  shall not be considered limiting in scope of the types and formulations of potting materials  28  that may efficaciously be used with discrete flexible pixel elements  10 . 
       FIG. 4  is an exploded isometric assembly view of a discrete flexible pixel element  10  showing potting assembly  20 , top encasement cover  30 , bottom gasket  32 , and potting material  28  residing in the potting assembly  20 . Top encasement cover  30  is a formed housing of an optically opaque plastic or similar material that has a cavity  30   a  of sufficient volume to operatively to receive an upper portion of potting assembly  20  therein and presenting a ring recess  30   b  within top encasement cover  30  for receiving a corresponding ring protrusion  22   a  of potting shell  22  enabling top encasement cover  30  to engage and conjoin potting shell  22  mechanically by snapping into place therewith. The top surface of the top encasement cover  30  also includes a plurality of holes  31   a - 31   n  for accommodating the partial protrusion of the light emitting elements  13 . 
     Bottom gasket  32  is a formed pliable gasket of plastic, rubber or similar durable material that has a ring extension  32   a  corresponding to a ring recess  34  formed by a recess  22   b  in potting shell  22  and a corresponding recess  30   c  in top encasement cover  30  when mechanically conjoined, as heretofore described. Bottom gasket  32  mechanically engages ring recess  34  by inserting the ring extension  32   a  therein in order to effect a closure between the top encasement cover  30  at recess  30   c  and potting shell  22  at recess  22   b.    
     Advantageously, top encasement cover  30  operatively engages with and conjoins potting shell  22 , and bottom gasket  32  operatively engages with and conjoins both top encasement cover  30  and potting shell  22 , by means of a mechanical fit and reliance on tension and compression forces without requiring the use of an adhesive or recourse to mechanical fasteners during assembly, thus reducing the cost of manufacture and further enabling recovery of the top encasement cover  30  and bottom gasket  32  on failure or damage of pixel element electronics  15 . 
       FIG. 5  is an assembled view of the components of  FIG. 4 . 
       FIG. 6A  is a cutaway assembly view of discrete flexible pixel element  10  showing potting assembly  20 , potting material  28 , top encasement cover  30 , and bottom gasket  32  in final assembly embodying an hermetically sealed, unitary, self-contained replaceable module. As shown, a plurality of light emitting elements  13  protrudes through an equal plurality of through-holes  31   a - 31   n  in the top encasement cover  30  to present an upper portion of said plurality of light emitting elements  13  to the exterior side of top encasement cover  30  permitting an unobstructed transmission of light. Mechanical fasteners  29  may be fixedly attached to a mounting surface or to a back plate  36  of an electronic display device. Alternatively, mechanical fasteners  29  may be conjoined to a detachable footing (not shown) that allows discrete flexible pixel elements  10  to be positioned in a nonfixed condition. Input connector  14  engages with and mechanically conjoins output connector  16   a  of the previous series connected discrete flexible pixel element  10   a . Output connector  16  engages with and mechanically conjoins input connector  14   b  of the next series connected discrete flexible pixel element  10   b.    
       FIG. 6B  is a cutaway assembly view similar to  FIG. 6A  but with a string of discrete flexible pixel elements  10  attached to a non-planar or irregular mounting surface  36 . 
       FIG. 7  is a cutaway assembly view of input connector  14  and output connector  16  showing internal components and corresponding fitment features enabling same to engage with and conjoin in closed mechanical fitment thereby to establish a sealed barrier to the atmosphere. Input connector shell  40  is a formed housing of plastic or similar electrically nonconductive material that supports a plurality of captive input terminal contacts  41   a  of flexible cable  18   a . Similarly, output connector shell  44  is a formed housing of plastic or similar electrically nonconductive material that supports a plurality of captive output terminal contacts  41   b  of flexible cable  18   b . An input connector key  42   a  mechanically engages with and conjoins a corresponding output connector key  42   b . An input connector protrusion  43   a  mechanically engages with and conjoins a corresponding output connector recess  43   b  by snapping into place. Input connector  14  with input terminal contacts  41   a  mechanically engage with and conjoin output connector  16  with output terminal contacts  41   b  in operative electrical connection therewith. Potting material  28  is applied to cavity  40   a  of input connector housing  40  to encapsulate and seal flexible cable  18   a  and providing strain relief and potting material is similarly applied to cavity  44   a  of output connector housing  44  for the same purpose. Upon engagement and mechanical connection, the terminal contacts  41   a  of input connector  14  engage with corresponding terminal contacts  41   b  of output connector  16  in a close mechanical fit thereby effecting an operative electrical connection between the input terminal contacts  41   a  and output terminal contacts  41   b  and simultaneously isolating them from the outside environment by virtue of the sealed barrier to the atmosphere. 
     Various modifications can be made to the present invention without departing from the apparent scope thereof. 
     PARTS LIST 
     
         
           10  discrete flexible pixel element 
           11  printed circuit board assembly 
           13  light emitting elements 
           13   a  electrical conductors 
           14  input connector 
           15  pixel element electronics 
           15   a  pixel element drivers 
           16  output connector 
           17  flexible cable header 
           18  flexible cables 
           19  flexible cable header 
           20  potting assembly 
           22  potting shell 
           22   a  ring protrusion 
           22   b  recess 
           24  upper cavity 
           24   a  upper cavity wall 
           24   b  cavity limit 
           26  lower cavity 
           26   a  lower cavity wall 
           26   b  cavity limit 
           28  potting material 
           29  mechanical fasteners 
           30  top encasement cover 
           30   a  cavity 
           30   b  ring recess 
           30   c  recess 
           31   a - n  holes 
           32  bottom gasket 
           32   a  ring extension 
           34  ring recess 
           36  back plate 
           40  input connector shell 
           40   a  cavity 
           41   a  input terminal contacts 
           41   b  output terminal contacts 
           42   a  input connector key 
           42   b  output connector key 
           43   a  input connector protrusion 
           43   b  output connector recess 
           44  output connector shell 
           44   a  cavity

Technology Category: g