Abstract:
A high voltage electrical connection between a base unit and a panel display in a portable computer wherein the base unit and the panel display are pivotably secured to each other about a hinge axis, includes a flexible high voltage electrical conductor extending from the base unit to the panel display. A portion of the electrical conductor extends along the hinge axis such that pivoting of the panel display relative to the base unit causes said portion of the flexible conductor to twist about the hinge axis rather than actively bend.

Description:
BACKGROUND  
         [0001]    Most notebook computers include a base unit which houses the processor and keyboard of the computer. A top cover which houses a display screen is pivotably secured to the base unit. Low voltage signals for controlling the display screen are provided from the base unit to the display screen by a thin planar flex circuit extending therebetween. The portion of the planar surface of the flex circuit which crosses the hinge axis of the notebook computer actively bends when the top cover opens or closes. The flex circuit has a very thin cross section and is made of material flexible enough to allow the flex circuit to withstand tens of thousands of bending cycles without breaking.  
           [0002]    The display screen is commonly backlit to improve viewing. The backlighting is typically powered by a high voltage inverter located within the top cover adjacent to the display screen. The high voltage inverter is enclosed within the top cover because the wires required for carrying high voltage power (about 1500 volts) have a much thicker cross section than a flex circuit making the high voltage wires less flexible and unable to withstand repeated bending cycles. Housing the inverter in the base unit would require the high voltage wires to extend across the hinge axis from the base unit to the display screen, subjecting the high voltage wires to breakage under the repeated bending and exposing the user to the possibility of 1500 volts of high voltage electrical shock.  
           [0003]    A drawback of positioning the inverter in the top cover adjacent to the display screen is that the display screen must be smaller than the top cover by at least an amount equal to the width of the inverter. The display screen can be made larger, by locating the inverter behind the display screen. However, this would increase the thickness of the top cover in order to accommodate the inverter, and would in turn increase the overall thickness of the notebook computer.  
         SUMMARY OF THE INVENTION  
         [0004]    The present invention is directed to a high voltage electrical connection between a base unit and a panel display in a portable computer wherein the base unit and the panel display are pivotably secured to each other about a hinge axis. The electrical connection includes a flexible high voltage electrical conductor extending from the base unit to the panel display. A portion of the electrical conductor extends along the hinge axis such that pivoting of the panel display relative to the base unit causes said portion of the flexible conductor to twist about the hinge axis rather than actively bend. Twisting a length of flexible conductor about its longitudinal axis exerts less stress on the flexible conductor than if the flexible conductor is repeatedly bent across its longitudinal axis.  
           [0005]    In preferred embodiments, the flexible electrical conductor includes two insulated copper braided wires positioned longitudinally adjacent to each other. A sleeve surrounds a portion of the flexible conductor. The sleeve is made of a braided material capable of being shrink fitted over the flexible conductor and prevents wear of the flexible conductor due to twisting of the flexible conductor against components of the computer. Each wire preferably includes 19 twisted tinned annealed copper wire strands about 0.127 mm in diameter which are covered by a polymeric insulation jacket.  
           [0006]    The present invention provides an electrical connection which allows the high voltage inverter of a notebook computer to be located in the base unit while at the same time, eliminating the possibility of conductor breakage and high voltage electrical shock to the user. As a result, the size of the display screen can be maximized without increasing the dimensions of the top cover. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.  
         [0008]    [0008]FIG. 1 is an exploded perspective view of a notebook computer including the present invention high voltage electrical connection with the keyboard and portions of the base unit housing removed.  
         [0009]    [0009]FIG. 2 is an enlarged perspective view depicting the manner in which the high voltage electrical conductor is electrically connected to the high voltage inverter in the base unit of the notebook computer of FIG. 1.  
         [0010]    [0010]FIG. 3 is an exploded perspective view of the top cover of the notebook computer of FIG. 1, depicting the manner in which the high voltage electrical conductor is electrically connected to the display screen.  
         [0011]    [0011]FIG. 4 is an enlarged perspective view of the present invention electrical conductor extending from the base unit to the top cover of the notebook computer of FIG. 1.  
         [0012]    [0012]FIG. 5 is a side view of one wire of the high voltage electrical conductor of the computer of FIG. 1 with portions of the wire being removed. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0013]    Referring to FIGS.  1 - 4 , notebook computer  10  includes a base unit  12  and a top cover  14  which are pivotably secured to each other by a pair of hinges  18  (FIG. 3) along a hinge axis X. The base unit  12  houses the keyboard (not shown), processor, drives etc. of the computer  10 . The top cover  14  supports the panel display  16  of computer  10 . Low voltage data signals to panel display  16  for controlling panel display  16  are provided by a conventional flex circuit extending between base unit  12  and top cover  14 . High voltage power (about 1500 volts) from a high voltage inverter  56  (FIG. 2) within base unit  12  is provided to panel display  16  by the present invention high voltage connection which includes a flexible high voltage conductor  26  extending between inverter  56  and panel display  16 . The high voltage power is used to backlight the panel display  16  using techniques in the art.  
         [0014]    Top cover  14  includes an outer cover  14   b  which supports panel display  16  and an inner frame member  14   a  which secures panel display  16  to outer cover  14   b  (FIG. 3). Inner frame member  14   a  and outer cover  14   b  include two respective inner  24   a  and outer  24   b  hinge cover halves which when joined together, form two hinge covers  24 . Two hinges  18  are spaced apart from each and enclosed within the interiors  44  (FIG. 4) of respective hinge covers  24 . Each hinge  18  includes a hinge body  18   b  mounted to outer cover  14   b  and a hinge mount  18   a  which is pivotably secured to hinge body  18   b  (FIG. 3). Each hinge mount  18   a  extends from the outer axial end of a hinge cover  24  and is secured by screws to a base mount  20  at the rear of base unit  12 , thereby pivotably securing top cover  14  to base unit  12  along hinge axis X (FIG. 1).  
         [0015]    As shown in FIG. 2, high voltage conductor  26  includes two insulated braided wires  30  and  32  positioned side-by-side. A flexible braided sleeve  28 , preferably about 1 inch wide, is shrink fitted over wires  32  and  30  on the portion of conductor  26  near base unit  12  (FIG. 4). If desired, a longer sleeve  28  can be employed. The lower end of wires  30 / 32  are electrically connected to a lower snap fit connector  26   a  which mates with inverter connector  34  (FIG. 2). The upper end of wires  30 / 32  are electrically connected to an upper snap fit connector  26   b  which mates with panel display connector  38   a  (FIG. 3). The snap fittings facilitate the assembly process. Conductor  26  extends upwardly from inverter connector  34  through an opening  46  in base unit housing  12   a  (FIG. 4). Conductor  26  is then bent at about 900 such that conductor  26  enters the right hinge cover  24  of top cover  14  through an opening  40  and lies within the interior  44  of hinge cover  24 . The portion of conductor  26  wrapped in sleeve  28  (about one inch) extends from opening  46  in base unit housing  12   a  into opening  40  of hinge cover  24 . The longitudinal axis of about a one inch length of conductor  26  lies approximately along the hinge axis X of notebook computer  10 . Conductor  26  is then bent again at about 900 to exit the interior  44  of hinge cover  24  and enter an opening  42  within outer cover  14   b  below display screen  16  to couple with panel display connector  38   a  (FIG. 3). Panel display connector  38   a  is electrically connected to panel display  16  by wires  38 .  
         [0016]    Top cover  14  is typically rotated about the hinge axis X approximately 135° when opened or closed. Such a range of motion would normally fatigue and break prior art high voltage wires if such wires were extended between top cover  14  and base unit  12  in a perpendicular relation to hinge axis X. The reason for this is that the same area of the wires are repeatedly bent approximately 135° whenever the top cover  14  is opened and closed. Bending wires at the same area exerts alternating stresses to that area which fatigues and breaks the wires.  
         [0017]    In contrast, in the present invention, by positioning a length of conductor  26  along the hinge axis X of notebook computer  10 , no active bending of conductor  26  occurs. Although the portions of conductor  26  which enter and exit hinge cover  24  are initially bent at approximately right angles during assembly, no further bending occurs during use. The only cyclic or repeated movement of conductor  26  which occurs during use is that the length of conductor  26  longitudinally lying along hinge axis X twists back and forth approximately 135° about hinge axis X as indicated by the arrow “A” (FIG. 4) when top cover  14  is pivoted open or closed. The braided sleeve  28  prevents the insulation  48  (FIG. 5) of wires  30 / 32  from rubbing against hinge cover  24  and base unit housing  12   a  when conductor  26  twists, so that the insulation  48  does not wear off. The twisting of conductor  26  occurs along the length of conductor  26  between about points  22  and  36  (FIG. 4). This distributes the alternating stresses on conductor  26  over about a one inch length of conductor  26  instead of at a single spot. This is a large enough area to prevent the conductor  26  from fatiguing. In fact, conductor  26  has survived tests of 20,000 cycles of opening and closing top cover  14 .  
         [0018]    The construction of wire  30  of conductor  26  is depicted in FIG. 5. Wire  32  (FIGS.  2 - 4 ) is similarly constructed. Wire  30  has an inner bundle  54  of seven wire strands  50  twisted around each other. The inner bundle  54  is surrounded by an outer series or bundle  52  of 12 wire strands  50  which are in turn twisted around inner bundle  54 . An outer polymeric insulation covering  48  surrounds the outer series  52  of wire strands  50 . The diameter of wire strands  50  is about 0.127 mm with the diameter of the entire conductor being about 0.64 mm. Wire strands  50  are preferably made of tinned annealed copper wire which has a temperature rating of about 105° C. Wire  30  has a voltage rating of about 3 KvDC and a maximum resistence of about 91.3 Ohm/Km at 20° C. Insulation  48  is preferably of double thickness and is about 0.48 mm thick with a diameter of about 1.6 mm +/−0.15 mm. Insulation  48  has a minimum resistance of about 1000 M Ohm/Km at 20° C. and a minimum tensile strength of about 1.06 Kg/mm 2 . Although the preferred number and diameter of wire strands  50  has been described above, the number and diameter of the wire strands can be varied slightly while still providing desirable mechanical properties.  
         [0019]    The length of conductor  26  is preferably about 5 ½ inches long but, alternatively, can be longer or shorter depending upon the location of inverter connector  34  or panel display connector  38   a . In addition, connectors  26   a / 26   b  are preferably made of plastic but alternatively can be metallic. Although wires  30  and  32  are depicted to be separate wires, alternatively, wires  30  and  32  can be molded to be side by side.  
         [0020]    Equivalents  
         [0021]    While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Those skilled in the art will recognize or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described specifically herein. Such equivalents are intended to be encompassed in the scope of the claims.  
         [0022]    For example, connectors  26   a ,  26   b ,  34  and  38   a  can be omitted. In such a case, the wires  30 / 32  would be connected directly to inverter  56  and panel display  16 .