Abstract:
An electrical receptacle for use in a string of holiday lighting that has a removable, replaceable, on-board power control board. The control board taps into normal alternating current delivered to the receptacle from a pair of wires running from an electrical plug and uses it to deliver electrical power through a fuse to a third wire that supplies current to a set of lights carried by the third wire as it runs from the receptacle back to the plug. The control board may also rectify the current to the third wire so that the lights operate on direct current rather than alternating current. However the receptacle delivers alternating current to subsequent load plugged into it. The control board is also capable, with suitable choices of components carried by it, of other modifications of the electrical current it delivers to the third wire.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
         [0001]    Not applicable.  
         STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
         [0002]    Not applicable.  
         REFERENCE TO A MICROFICHE APPENDIX  
         [0003]    Not applicable  
         BACKGROUND OF THE INVENTION  
         [0004]    Households and businesses are supplied with 120-volt alternating current (AC) for use in providing electrical power to a number of devices, including small appliances and lighting. AC is typically supplied to a receptacle in a wall outlet. When the need for electrical power is located at a distance from the wall outlet, an extension cord may be used to deliver the power to where it is needed. One end of the cord plugs into the wall outlet receptacle, and the opposing end of the cord provides a receptacle for use in connecting the electrical load.  
           [0005]    Not all electrical loads require AC. Some require direct current (DC). DC can be obtained from a wall outlet using a rectifier to rectify the AC. Many consumer electronic devices such as computers and cordless telephones use DC instead of AC.  
           [0006]    The range of devices using AC or DC varies considerably and is growing. The number of devices that may be plugged into a wall outlet receptacle is limited. Various devices exist to increase the number of receptacles and in some cases a series of loads have their own receptacles.  
           [0007]    For example, strings of holiday lights have a plug for the AC wall outlet at one end and a receptacle at the other end so that additional strings can be plugged into and thereby powered by the first string. This arrangement is not without its problems. The current that can be drawn by several strings put together can pose a hazard. Accodingly, many holiday light strings carry a fuse to limit current. However, when up to three strings are connected together the fuse used to limit current must still pass considerable current, perhaps six or seven amperes. Consequently, consumers who may use more than three strings to decorate have to use at least two receptacles and still run the risk of an electrical hazard.  
           [0008]    Strings of holidays lights have been developed by the present inventor that operate on DC rather than AC. These strings have rectifiers in the plug or the first light socket that convert the incoming AC to DC and provide fuse protection for the circuit.  
           [0009]    As the nature and variety of appliances and uses for electricity increases, so too does the desire to control use so that products are not damaged and good use is made of the electricity consumed. Also, there is greater interest in the measurement of electricity consumed. Thus, there is a need for a device that provides a convenient source of electrical current, including AC or DC, and potentially offers unprecedented control over the current being used.  
         SUMMARY OF THE INVENTION  
         [0010]    The present invention is a device for delivering electrical current. In one embodiment, it is an extension cord with a receptacle on one end that allows control and monitoring of the electrical current it delivers to the device plugged into its receptacle. In another embodiment, it is a three-wire AC extension cord that provides electrical power to a first load while delivering AC to a second electrical load plugged into it. In a modification of this embodiment, the first load is a DC load such as a string of lights.  
           [0011]    The present invention comprises a plug connected to a receptacle using three electrically conducting wires: a line wire, a neutral wire and a third wire that simply terminates in the plug without electrical contact there. The receptacle has an on-board power control device that is arranged electrically in parallel with the receptacle&#39;s contacts. The power control device delivers electrical power to a load attached to the neutral wire and the third wire. Depending on the configuration of the power control device, the electrical power can be AC or DC, can be fused, stepped down in voltage, or can be controlled in other ways.  
           [0012]    A feature of the present invention is the on-board power control device. This device serves as a “mother board” for a wide range of applications without modification of the balance of the device. Furthermore, because it is easily replaceable and may have “daughter boards,” can be used to adapt the present device for other uses.  
           [0013]    Another feature of the present invention is the manner in which the power control device taps into the power of the line and neutral wires, or just the neutral wire, to provide the desired control to the third wire.  
           [0014]    Still another feature of the present invention is the ability to provide a separate fuse for the third wire load. In the context of a holiday light string, the ability to fuse each string separately makes it possible to use more than three strings in sequence and to use fuses with smaller ratings for each string. This feature means each light string is safer.  
           [0015]    These an other features and their advantages will be apparent to those skilled in the household electrical arts from a careful reading of the Detailed Description of Preferred Embodiments, accompanied by the following drawings. 
       
    
    
     BRIEF DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0016]    In the drawings,  
         [0017]    [0017]FIG. 1 is a perspective view of a receptacle according to a preferred embodiment of the present invention;  
         [0018]    [0018]FIG. 2 is a top view of the present receptacle taken along lines  2 - 2  of FIG. 1, according to a preferred embodiment of the present invention;  
         [0019]    [0019]FIG. 3 is a top view of the receptacle of FIG. 2 with the power section and fuse section partially separated;  
         [0020]    [0020]FIG. 4 is a top view of the receptacle of FIG. 2 with the power section, power circuit board, and fuse section completely separated;  
         [0021]    [0021]FIG. 5 is a perspective view of the power section and fuse board;  
         [0022]    [0022]FIG. 6 is a perspective view of the fuse section;  
         [0023]    [0023]FIG. 7 is a detailed view of the power section and fuse board showing the AC and DC terminals;  
         [0024]    [0024]FIG. 8 is a perspective view of the fuse board, according to a preferred embodiment of the present invention;  
         [0025]    [0025]FIG. 9 is a detailed, perspective view of the AC terminal, according to a preferred embodiment of the present invention;  
         [0026]    [0026]FIG. 10 is a detailed, perspective view of the DC terminal, according to a preferred embodiment of the present invention;  
         [0027]    [0027]FIG. 11 is a detailed view of the end of the power section showing the protective lid, according to a preferred embodiment of the present invention; and  
         [0028]    [0028]FIG. 12 is a schemative view of an embodiment of the present invention in use as a holiday light string. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0029]    The present invention is a device for use in delivering electrical current to one or more loads. One load may be powered directly by the device and, indeed, may be incorporated into the device. The other load is plugged into the device and is thus powered indirectly.  
         [0030]    As shown in FIG. 1, the present device includes an electrical plug  10  connected to a receptacle  14  with three wires  20 ,  22 ,  24 . Plug  10  is a conventional two-prong plug with two electrical contacts or prongs  32 ,  34 , entending therefrom and adapted to plug into another electrical receptacle. The present plug&#39;s prong configuration can be adapted to accommodate receptacles standard in countries other than the US.  
         [0031]    Wires  20 ,  22 ,  24 , are all electrical conductors insulated from the environment and each other, and are preferably formed as a flat “ribbon.” First wire  20  is a line conductor; second wire  22  is a neutral conductor; and third wire  24  supplies electrical current directly to a load, as will be described herein.  
         [0032]    Receptacle  14  includes a housing  40  with a power section  44  and a fuse section  48 . Power section  44  slides into fuse section  48 , as shown, but with minor modification, fuse section  48  could be made to slide into power section  44 . When power section  44  is fully seated in fuse section  48 , the two are secured together with a locking screw  50 . First, second and third wires  20 ,  22 ,  24 , enter housing  40  through power section  44 ; two holes  56 ,  58 , formed in fuse section  48  are dimensioned for receiving the prongs  62  of a plug  64  from an electrical appliance or other electrical load.  
         [0033]    As shown in FIG. 1, at the end of power section  44  is a cavity  70  for first, second and third wires  20 ,  22 ,  24 . Cavity  70  is covered by a protective lid  72  that has three cutout portions  76 . Power section  44  also has three cutout portions  82  that can be aligned with the cutout portions  76  of protective lid  72  to form an opening through which first, second and third wires  20 ,  22 ,  24 , pass. Preferably protective lid  72  , once installed in power section  44 , cannot be removed. Furthermore, the opening is somewhat undersized so that it makes a water-tight, “choke” seal against the insulation on first, second and third wires  20 ,  22 ,  24 .  
         [0034]    FIGS.  2 - 4  illustrate how power section  44  and fuse section  48  separate and reveal their internal components. FIG. 2 is a cross section of receptacle  14  of FIG. 1, taken along lines  2 - 2 . First, second and third wires  20 ,  22 ,  24 , are shown entering power section  44 , and ending in terminals  86 ,  88 ,  90 , respectively, that are crimped to the bare, uninsulated ends of these wires and seated near the end of receptacle  14 . First and second wires  20 ,  22 , are seated at the bottoms of narrow, deep channels  94 ,  98 . Third wire  24  is seated at the bottom of a thin, deep channel  102  between channels  94  and  98 .  
         [0035]    In fuse section  48  are three more channels. A first channel  106  contains a buss bar  110  with a spring contact  112  in electrical connection, and preferably also integrally connected, to it. Spring contact  112  is adapted to be resiliently urged to the side but remain engaged with one prong  62  of plug  64  that enters hole  56 .  
         [0036]    A second channel  118  has a fuse holder  122 , holding a fuse  124 , and also, connected electrically and preferably integrally, a spring contact  126  that operates in an manner similar to that of spring contact  112 . The choice of fuse  124  will help to limit the current passing therethrough in the event of a power surge or demand that exceeds that rating of the circuit.  
         [0037]    Note that fuse  124  and buss bar  110  extend beyond fuse section  48  toward power section  44  so that, when fuse section  48  and power section  44  are joined, buss bar  110  and fuse  126  make contact with first and second terminals  86 ,  88 m at the bottoms of channels  94 ,  98 , respectively, and, thus form two electrical paths. The first path runs from first wire  20 , through terminal  86  and buss bar  110 , to spring contact  112 . The second path runs from third wire  24  through terminal  88  and fuse  124 , to spring contact  126 . These paths can be used to deliver fused AC from plug  10  to an electrical device plugged into receptacle  14 .  
         [0038]    As power and fuse sections  44 ,  48 , are separated, note that buss bar  110  and fuse  126  remain with fuse section  48  and break contact with terminals  86 ,  86 , respectively. Terminals  86 ,  88 , because they are deep in channels  94 ,  98 , are not likely to cause injury to a user who may be separating the two sections in order to change fuse  126 , replace buss bar  110  with a fuse, fuse holder and spring contact, or replace a power control board  130 , the function of which will shortly be described.  
         [0039]    Power control board  130  is a small circuit board that may hold electrical components and microprocessors selected for particular functions. The choice of components will dictate how board  130  controls power to third wire  24  and, when desired, to first and second wires  20 ,  22 , as well.  
         [0040]    A first end  134  of control board  130  is received power section  44  in channel  102  and held in place by four supports  142 . Its second end  146  extends from power section  44  when power section  44  has been separated from fuse section  48  but, when they are joined, will be received in a channel  152 , located between channels  106  and  118  of fuse section  48 , where another four supports  154  help to hold control board  130  in position.  
         [0041]    Control board  130  is maintained in electrical connection with first and second terminals  86 ,  88 , using terminal connectors  160  of the type illustrated in FIG. 9. These have a saddle section  162  that engages the end of a wire, a flexing cap  168  to receive the end of a buss bar or fuse, and a board contact  170  for contacting or gripping components on control board  130 .  
         [0042]    A terminal connector  174  of the type shown in FIG. 10 is used to make electrical connection with third wire  24 . Terminal connector  174  has a saddle section  176  and a board contact  180  equivalent to those of terminal connector  160 . Preferably, terminal connectors  160 ,  174 , are made of sheet stock that is die cut and folded.  
         [0043]    Power control board  130  may have any of the following functions. It may facilitate the delivery of AC or DC power to third wire  24  either with full voltage or stepped down; it may cause that power delivered to third wire  24  to vary in voltage or to pulse or to switch on and off in response to a computer program, in response to sensors, or on command. The commands can be based on a local switch carried by receptacle  14  or a remotely transmitted signal. Power control board  130  may control the voltage across first and second wires  20 ,  22 , as well. Power control board  130  may also monitor the electrical power passing through wires  20 ,  22 ,  24 .  
         [0044]    [0044]FIG. 8 illustrates a particular embodiment of components on power control board  130 . There is a fuse  184  and a rectifier  188 , such as a simple diode that passes current in one direction only, thus rectifying the current being tapped from second wire  22  and passing the rectified current through fuse  184  to the third wire  24  via third terminal  90 .  
         [0045]    An example of the use of power control board  130  is shown in FIG. 12. The device shown in FIG. 12 is a string of holiday lighting  192 . String  192  has a plug  194  on one end, a receptacle  196  according to the present invention on the other end and three wires  198 ,  200 ,  202  connected to plug  194  and receptacle  196 . First and second wires  198 ,  200 , are connected electrically with prongs  204 ,  206 , on plug  194 ; third wire  202  is not, but merely dead ends in plug  194 . A series of small lights  208 , such as C7 or C9 bulbs, are connected in parallel to each other across first and third wires  198 , 202 , respectively. Lights  208  operate off fused DC delivered to third wire  202  by a power control board  130  of the kind described above, having a control board  210  that alters the AC delivered to first and second wires  198 ,  200 , to produce DC for third wire  202 . Note that full AC is delivered to and can be passed by receptacle  196  via a fuse  212  to another plug  214 , such as that on another string of lights.  
         [0046]    The load on string  192 , namely, the series of lights  208 , is separately fused, as could be each of three or more additional strings connected to string. If lights are low watt, efficient bulbs, up to six strings of lights can be strung together operating from power from a single wall receptacle, with low rated, one ampere fuses limiting the current in each string.  
         [0047]    It will be apparent to those skilled in the art of electrical appliance power supplies that many modifications and substitutions can be made to the foregoing preferred embodiments without departing from the spirit and scope of the present invention, defined by the appended claims.