Abstract:
Apparatus and method for supporting a large number of densely arranged and electrically shielded panels are disclosed. To achieve shielding each panel has a grounded back plane which acts as shielding for circuitry on an adjacent panel as well as shielding for its own circuitry.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application claims priority from the following application: U.S. application Ser. No.: 60/135,623, filed May 24, 1999. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     This invention relates to communication distribution equipment, and more specifically to methods and apparatus for supporting a multiplicity of densely arranged or packed electrical shielded communication panels, each of which has a ground or conductive sheet covering the back side of the panel to provide back side shielding to the circuitry on that same panel as well as front side shielding to an adjacent panel. 
     SUMMARY OF THE INVENTION 
     The present invention includes apparatus and methods for supporting a multiplicity of densely-arranged and electrically-shielded panels. The apparatus and methods include a distribution structure, which has a rack or panel area for supporting at least two and, in a preferred embodiment, up to 20 adjacent panels at one level of the distribution cabinet. The cabinet itself will include a grounding or electrical connection point to which all of the panels are connected by a low resistance path. To achieve the shielding provided by the apparatus of this invention, there are included at least two similar panels carrying electrical signals which are supported adjacent and in close alignment to each other by the support rack. Each of the two panels comprises a face plate for securing the panels to the rack and in a preferred embodiment includes cable connectors to terminals for providing a plurality of input communication signals and a single output communication signal made up of the combined input signals. Each of the panels will include a printed circuit board which extends perpendicularly away from the face plate and which is made up of an insulating substrate having a circuit side and a back side. The circuit side includes a printed circuit, which is printed on the substrate by well-known printed circuit techniques. And the back side includes a conducted sheet or ground which is printed or otherwise secured to and substantially covers the back side of the substrate. A low-resistance conductive path exists between the conductive sheet on the circuit board and the electrical connection point of the rack or distribution cabinet such that each panel includes a low-resistance path between the conductive sheet and the connection point (normally ground) on the rack. As mentioned above, the connection point on rack is usually a grounding point such that all of the conductive sheets on each of the panels are at ground potential. 
     The adjacent panels are closely aligned and supported in the support rack so that the printed circuit of one of the panels is electrically shielded on its back side by the conductive sheet on that same panel and on its circuit or front side by the conductive sheet of the adjacent panel. According to a preferred embodiment, each of the panels is a panel for combining RF communication electrical signals which operate over a bandwidth at a selected center frequency. The printed circuit is simple and straightforward in that it provides electrical combination of incoming signals to a single output connector, such that a combination of signals is provided at the single output terminal. Also in a preferred embodiment, the printed circuit paths will be selected such that there is a constant resistence such as 75 ohms between each of the input terminals and the single output terminal. As will be appreciated by those skilled in the art, a path resistance of 75 ohms is standard for coaxial cable since the loss in the cable is at a minimum at that impedance. When sending high-speed signals, it is preferred that the transmission line impedance be maintained the same over the signal path. Maintaining the same impedance enables the maximum power transfer. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other features of the present invention will be more fully disclosed when taken in conjunction with the following Detailed Description of the invention which like numerals represent like elements and in which: 
     FIG.  1 . is a diagrammatic representation of a support structure or cabinet having at least one panel area, or rack with dimensions suitable for supporting densely-aligned panels of the present invention. Other panel areas or racks of the support structure or cabinet may include power supplies, light-emitting generators, cooling fans, and the like; 
     FIG. 2 shows the panel area of FIG. 1, which receives the densely-aligned shielded panels of the present invention; 
     FIGS. 3 a ,  3   b , and  3   c  are a side view, front view, and bottom view respectively of one embodiment of electrically-shielded panels of the present invention suitable for being densely arranged with similar type panels; 
     FIG. 4 is a highly enlarged and detailed view of the FIG. 3 c  bottom view for illustrating details of the panel; 
     FIGS. 5 a  and  5   b  show still another embodiment of the shielded panels of the present invention; 
     FIGS. 6 a ,  6   b  and  6   c  show yet another embodiment of a panel of the present invention suitable for being densely arranged with like panels; and 
     FIG. 7 is another bottom view of the different type connector terminals used on the electrically-shielded panels of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to FIG. 1, there is shown a support structure or cabinet  10 , which in the embodiment shown, has at least one rack area  12  as well as second and third panel or rack areas  16  and  18 . It should be appreciated that the distribution within the structure or cabinet  10  may well include other areas for different panels, including other areas for panels of the present invention, such as panel or rack area  12 . However, for explanation purposes only, there is shown one panel or rack area  12 , a panel or rack area  16  with a power supply  20  and four optical transmitters  22 - 28  for generating light at specific wavelengths of light commonly referred to as λ. The panel or rack area  18  typically might include a cooling fan  30  as well as four other additional optical-transmitting devices  32 - 38  for generating wavelengths of light still different from those of panels  22 ,  24 ,  26 , and  28  above. Cabinet  10  includes an electrical connection point  11  which typically is connected to ground. 
     Referring now to FIG. 2, there is shown a group of panels  14  located in panel or rack area  12  supported by the cabinet structure  10 . Typically, the panel or rack area  12  will include a rack or support pocket  40 , which will typically be a box-like structure supported in the cabinet  10  by support brackets  42  and  44 . The receiving rack  40  will include at least a bottom support member  46  and a top support member  48 . In the embodiment shown, there are 20 densely-aligned and arranged connection panels  50  through  88 . Also in the embodiment shown, there is a front portion or face plate on each of the panels, such as front portion or face plate  90  on panel  50 . Each front portion or face plate includes a mounting screw or lug  92  received by support bracket  48 . Also as shown in FIG. 2, it is seen that panels  50  through  80  have eight input terminals in one group and a single output terminal at the bottom of the rack. As will be discussed later, the eight top terminals  50   a  through  50   h  are for receiving up to eight different input signals which may have the same or different frequencies, which signals are then combined and provided as a single output on the bottom output terminal  50 . Panels  82  through  88 , on the other hand, are dual combining circuits. That is, there are two combining circuits on each panel. The panels illustrated in FIG. 2 show four different types of dual panels. 
     As shown, panel  82  includes 10 connectors of the same type. The first four top connectors are input terminals, as discussed above. The next terminal, however, indicated in the drawing as  82   w , is a first output terminal providing a combined output to the signals received from the four top connectors. In a similar manner, the next four terminals are the input terminals for the second combining circuit on panel  82 , and terminal  82   x  is the output terminal for the combined signals received from the bottom four input terminals. 
     Panel  84  is almost identical to panel  82 , except the lower-most output terminal  84   z  is larger than terminal  82   x  and is for connecting to a larger connection terminal on heavy-duty coaxial cables. Panel  86  is similar to panel  84 , except the output terminal  86   y  is also a large output terminal of the same type as  84   z .This larger connection terminal is often referred to as an “F” connector. It is also noted that the panel  88  does not include the top four input terminals or the top output terminals, as did panels  82 ,  84 , and  86 . In some instances, the circuits may be on the printed circuit board and just not brought to the front of the panel or in other instances, the circuit boards may be manufactured without these second circuits. 
     Referring now to FIGS. 3 a ,  3   b , and  3   c , there is shown a side view, a front view and a bottom view of the panel  50 , which, of course, is also similar to the panels  52  and  80 . These views clearly show the connecting lug  92  which is attached to the face plate or front portion  94  of panel  50 . As shown more clearly in FIG. 3C, a printed circuit board  96  extends perpendicularly to the face plate or front portion  94  of panel  50 . The face plate or front portion  94  of the panel includes a first edge member  98  for support and a second support member  100 , which it will be noticed also includes an extension  102  which abuts the conductive sheet  112  on the backside  104  of the printed circuit board  96 . Although it will be appreciated that various and different types of circuit boards may benefit from the teachings of the present invention, according to one embodiment the circuit board is used for combining electrical RF signals, each having a bandwidth around a different center frequency. The printed circuit board will include on connection path from each of the input terminals  50   a  through  50   h  such that each of these terminals provides a constant input impedance, such as, for example,  75  ohms. A single printed connection path will run from the common connection point of the output terminal  50   v , and would also provide a constant impedance from the connection point to the output terminal. Referring now to FIG. 4, there is shown a highly-enlarged view of the bottom view FIG. 3 c . As shown, the printed circuit board  96  will include an insulating substrate  106 , having a front side with a printed circuit thereon. In the portion of the circuit board shown in FIG. 4, part of the printed circuit is shown as section  108 . The printed circuit will also include on the back side  110  of the substrate  106  a conductive sheet  112 , which is substantially co-extensive with the overall size of the printed circuit board. As will be appreciated by those skilled in the art, the conductive sheet  112  will typically act as a grounding plane to provide electrical shielding. Also as shown, the extension  102  of front portion  94  of panel  50  is in electrical contact with the conductive sheet  112 . 
     Also as shown in the figures, and more clearly in FIG. 4, the connection terminals  50   a  through  50   h  and  50   v  include a rear portion  114 ; a throat portion  116  and an outward securing portion  118  which may be unitary with the cable-receiving portion  120 . This type terminal is shown such that the throat portion  116  extends through an aperture  122  in front panel  94  to which is then attached the outward portion  118 . As shown, of course, the diameter of portions  114  and  118  are larger than the aperture at  122  such that the  5  terminal may be secured tightly to the faceplate  94 . This may be accomplished by tightening the outward portion  118  on threads cut into the portion  116 . This type of terminal may be referred to as an edge terminal, as it makes an electrical connection to the edges of conductive plate  112  and circuit portion  108  without requiring soldering or other permanent attachments. For example, the printed circuit portion  108  and the conductive sheet  112  are in a tight frictional electrical contact with conductors  116  and  118  respectively on the internal portion of the terminal  114 . 
     Referring now to FIGS. 5 a  and  5   b , there is shown a side view and front view of the dual combination panel  82 . As can readily be seen, this panel includes a first portion or combination circuit which has input terminals  82   a  through  82   d , which provide their inputs to a single output terminal  82   w  and a second circuit, which includes inputs  82   e  through  82   h , which have their inputs combined and provided on a single output  82   x.    
     Referring now to FIGS. 6 a  and  6   b , there is shown a panel design similar to that of panel  86 . It will be appreciated from FIGS. 6 a  and  6   b , along with FIG. 5 a ,that panel  86  is substantially similar as the panel shown in FIG. 5 a , except it includes two heavy-duty connectors  86   y  and  86   z . Although there is no illustration shown for panel  84 , it will substantially similar to the dual circuitry with respect to FIG. 5 a  except it will include one small connector, such as connector  82   x  and one large output connector such as  86   z.    
     Finally, FIG. 6 c  shows a front portion suitable for use with the dual circuit of FIG. 6 a  where the first portion of the circuit, having inputs  88   a  through  88   d  and output  82   x  are not brought out to the front panel. Again, as mentioned above, the circuitry portion used by the input terminals  88   a  through  88   d  and output terminal  86   y  may either be provided and not brought to the front of the panel, or simply not printed onto the circuit board. 
     FIG. 7 shows the bottom view of the panel such as shown in FIGS. 6 a ,  6   b ,and  6   c.    
     The corresponding structures, materials, acts, and equivalents of all means or steps, plus function elements in the claims below, are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed.