Patent Abstract:
A lampholder for receiving a cap of a lamp includes a body, a receiving portion, and lead wires: the receiving portion is provided in the body and to be connected to the cap; the lead wires are connected to the receiving portion. The receiving portion is made of conductive resin. This configuration can reduce the parts, simplify assembly, lower the cost, and improve the productivity.

Full Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a lampholder. 
     2. Description of the Related Art 
     As shown in FIG. 9, a conventional lampholder includes a body  47 , a female screw shell  48 , a central contact spring  49 , a cover  50 , power terminal boards  52   a,    52   b,  and lead wires  53   a,    53   b.  The body  47  is made of insulating resin or ceramic and is in the form of a cylinder with the bottom. The female screw shell  48  is made of metal and connected electrically to a shell (not shown), e.g., of an E-type cap (not shown) for a lamp (not shown). Similarly, the central contact spring  49  is made of metal and connected electrically to an eyelet (not shown) of the cap. The cover  50  is made of insulating resin or ceramic and provided at the end of the body  47 . The power terminal boards  52   a,    52   b  are fastened on the inner surface of the cover  50  with a pair of screws  51  (one of them is not shown). The lead wires  53   a,    53   b  are connected electrically to the power terminal boards  52   a,    52   b.    
     The body  47  and the cover  50  are connected mechanically with two screws  54   a,    54   b.  One screw  54   a  mechanically connects the body  47  and the female screw shell  48 , and also electrically connects the female screw shell  48  and the power terminal board  52   a.  The other screw  54   b  mechanically connects the body  47  and the central contact spring  49 , and also electrically connects the central contact spring  49  and the power terminal board  52   b.    
     A screw  55  is used to adjust the amount of movement of the central contact spring  49  when the cap is inserted. The screw  55  prevents the contact failure between the central contact spring  49  and the eyelet resulting from unnecessary movement of the central contact spring  49  toward the cover  50 . 
     However, in the conventional lampholder, many screws or the like are necessary to fasten each part together, particularly, to fasten the component of resin or ceramic, such as the body  47 , and that of metal, such as the female screw shell  48 . This requires the steps of tightening those screws as well. In other words, the parts are increased and the process is complicated, which in turn increases the cost and reduces the productivity. 
     SUMMARY OF THE INVENTION 
     Therefore, with the foregoing in mind, it is an object of the present invention to provide a lampholder that can achieve the reduction of cost and the improvement of productivity by reducing the parts and simplifying the process. 
     A lampholder of the present invention for receiving a lamp cap includes a body, a receiving portion provided in the body and to be connected to the cap, and a lead wire connected to the receiving portion. The receiving portion is made of conductive resin. 
     Unlike a conventional lampholder, this configuration eliminates the need to fasten the component of resin or ceramic, such as a body, and that of metal, such as a female screw shell, together. Therefore, many screws or the like are not necessary. As a result, the parts can be reduced and the steps of tightening the screws or the like can be omitted. Thus, the reduction of cost as well as the improvement of productivity can be achieved. 
     These and other advantages of the present invention will become apparent to those skilled in the art upon reading and understanding the following detailed description with reference to the accompanying figures. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross-sectional front view showing a lampholder of Embodiment 1 of the present invention. 
     FIG. 2 is a cross-sectional front view showing a lampholder of Embodiment 2 of the present invention. 
     FIG. 3 is a cross-sectional front view showing a lampholder of Embodiment 3 of the present invention. 
     FIG. 4 is a cross-sectional front view showing a lampholder of Embodiment 4 of the present invention. 
     FIG. 5 is a cross-sectional front view showing a lampholder of Embodiment 5 of the present invention. 
     FIG. 6 is a cross-sectional front view showing a lampholder of Embodiment 6 of the present invention. 
     FIG. 7 is a cross-sectional front view showing a lampholder of Embodiment 7 of the present invention. 
     FIG. 8 is a cross-sectional front view showing a lampholder of Embodiment 8 of the present invention. 
     FIG. 9 is a cross-sectional front view showing a conventional lamp holder. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. 
     Embodiment 1 
     As shown in FIG. 1, an E-type cap  2  (e.g., E26-type), e.g., for a bulb-shaped fluorescent lamp  1  is inserted in a lampholder of Embodiment 1 of the present invention. 
     The lampholder includes a body  3 , a receiving portion  4 , and a cover  5 . The body  3  is made of insulating resin and is in the form of a cylinder having a length of 35 mm, outer diameter of 35 mm, and inner diameter of 30 mm. The receiving portion  4  is made of conductive resin, provided on the inner surface of the body  3 , and to be connected electrically to the cap  2 . The cover  5  has a height of 15 mm and outer diameter of 35 mm, and is provided at the end of the body  3 . 
     The body  3  and the receiving portion  4  are formed as an integral component. 
     The body  3  is connected to the cover  5  by engaging a convexity  3   a  at the end of the body  3  with a concavity  5   a  at the end of the cover  5 . 
     Examples of the conductive resin used for the receiving portion  4  include a material prepared by mixing polybutylene terephthalate resin or polyphenylene sulfide resin with a conductive material, such as carbon black, metallic fiber, carbon fiber, metallic flakes, metallized glass beads, metallized glass fiber, and organic polymer. 
     The receiving portion  4  is provided with a first terminal  6  and a second terminal  7 . The first terminal  6  has an internal thread  6   a  on the inner surface, into which a shell  2   a  of the cap  2 , having an external thread, is screwed to establish the electrical connection between them. The second terminal  7  has a protruding contact portion  7   a  (with a protrusion length of 1 mm to 3 mm) that is connected electrically to an eyelet  2   b  at the end of the cap  2 . The ends of the lead wires  8   a,    8   b,  having a cross-sectional area of 0.75 mm 2  to 1.25 mm 2 , are embedded directly in the first and the second terminals  6 ,  7 , respectively, to establish the electrical connection. The length of the embedded portion of each lead wire  8   a,    8   b  is 5 mm or more. The other ends of the lead wires  8   a,    8   b  are drawn from a hole  5   b  in the center of the cover  5  to the outside of the lampholder. An insulating member  9  is provided between the first terminal  6  and the second terminal  7  to insulate the two terminals from one another. 
     Unlike a conventional lampholder, the above configuration of a lampholder of Embodiment 1 of the present invention eliminates the need to fasten the component of resin or ceramic, such as a body, and that of metal, such as a female screw shell, together. Therefore, many screws or the like are not necessary. As a result, the parts can be reduced significantly and the steps of tightening the screws or the like also can be reduced, compared with the conventional lampholder. Thus, the reduction of cost as well as the improvement of productivity can be achieved. 
     In particular, since the body  3  of insulating resin and the receiving portion  4  of conductive resin are formed as an integral component, the assembly of the body  3  and the receiving portion  4  can be omitted, thus increasing the productivity further. 
     Embodiment 2 
     Next, a lampholder of Embodiment 2 of the present invention has the same configuration as that of a lampholder of Embodiment 1 of the present invention except that the structure of a receiving portion  10  and a means for connecting lead wires  8   a,    8   b  and the receiving portion  10  are different, as shown in FIG.  2 . 
     The receiving portion  10  is provided with a first terminal  11  and a second terminal  12 . The first terminal  11  is made of conductive resin and has an internal thread  11   a  on the inner surface, into which a shell (not shown) of a cap (not shown), having an external thread, is screwed to establish the electrical connection between them. The second terminal  12  is made of conductive resin and has a protruding contact portion  12   a  (with a protrusion length of 1 mm to 3 mm) that is connected electrically to an eyelet (not shown) at the end of the cap. A body  3  and the receiving portion  10  are formed as an integral component. 
     An insulating member  9  is provided between the first terminal  11  and the second terminal  12  to insulate the two terminals from one another. Each of the first and the second terminals  11 ,  12  has a through hole  14  for screws so that a fastener  13  composed, e.g., of a tapping screw is driven into the hole. 
     The lead wire  8   a  is connected electrically to the first terminal  11  by fastening a pressure connector  15  with the fastener  13 , the pressure connector  15  being connected to the end of the lead wire  8   a.    
     Similarly, the lead wire  8   b  is connected electrically to the second terminal  12  by fastening a pressure connector  15  with the fastener  13 , the pressure connector  15  being connected to the end of the lead wire  8   b.    
     In FIG. 2, reference numeral  16  indicates a washer. 
     Unlike a conventional lampholder, the above configuration of a lampholder of Embodiment 2 of the present invention eliminates the need to fasten the component of resin or ceramic, such as a body, and that of metal, such as a female screw shell, together. Therefore, many screws or the like are not necessary. As a result, the parts and the steps of tightening the screws or the like can be reduced, compared with the conventional lampholder. Thus, the reduction of cost as well as the improvement of productivity can be achieved. In addition, the lead wires  8   a,    8   b  can be removed from the lampholder easily, which facilitates the replacement of damaged parts caused, e.g., by disconnection of the lead wires  8   a,    8   b.    
     Embodiment 3 
     Next, a lampholder of Embodiment 3 of the present invention has the same configuration as that of a lampholder of Embodiment 2 of the present invention except that screws (fasteners  17   a  in FIG. 3) and nuts (fasteners  17   b  in FIG. 3) are used instead of tapping screws to connect a receiving portion  10  and lead wires  8   a,    8   b  electrically, as shown in FIG.  3 . 
     In FIG. 3, reference numeral  18  indicates a hole for screws. 
     Unlike a conventional lampholder, the above configuration of a lampholder of Embodiment 3 of the present invention eliminates the need to fasten the component of resin or ceramic, such as a body, and that of metal, such as a female screw shell, together, just as in the lampholder of Embodiment 2 of the present invention. Therefore, many screws or the like are not necessary. As a result, the parts and the steps of tightening the screws or the like can be reduced, compared with the conventional lampholder. Thus, the reduction of cost as well as the improvement of productivity can be achieved. In addition, the lead wires  8   a,    8   b  can be removed from the lampholder easily, which facilitates the replacement of damaged parts caused, e.g., by disconnection of the lead wires  8   a,    8   b.    
     Embodiment 4 
     Next, a lampholder of Embodiment 4 of the present invention includes a body  19 , a receiving portion  20 , and a cover  21 , as shown in FIG.  4 . The body  19  is made of insulating resin and is in the form of a cylinder having a length of 35 mm, outer diameter of 35 mm, and inner diameter of 30 mm. The receiving portion  20  is made of conductive resin, provided on the inner surface of the body  19 , and to be connected electrically to a cap (not shown). The cover  21  has a height of 15 mm and outer diameter of 35 mm, and is provided at the end of the body  19 . 
     The body  19  and the receiving portion  20  are formed as an integral component. 
     The receiving portion  20  is provided with a first terminal  22  and a second terminal  23 . The first terminal  22  has an internal thread  22   a  on the inner surface, into which a shell (not shown) of the cap, having an external thread, is screwed to establish the electrical connection between them. The second terminal  23  has a protruding contact portion  23   a  (with a protrusion length of 1 mm to 3 mm) that is connected electrically to an eyelet (not shown) at the end of the cap. Each of the first and the second terminals  22 ,  23  has a through hole  25  for screws so that a fastener  24  composed, e.g., of a screw is inserted into the hole. An insulating member  9  is provided between the first terminal  22  and the second terminal  23  to insulate the two terminals from one another. 
     The cover  21  has power terminal boards  27   a,    27   b  on the inner surface, the power terminal boards  27   a,    27   b  being connected electrically to the ends of the lead wires  8   a,    8   b  by a pair of screws  26  (one of them is not shown). The other ends of the lead wires  8   a,    8   b  are drawn from a hole  21   a  in the center of the cover  21  to the outside of the lampholder. 
     The first terminal  22  and the power terminal board  27   a  are connected electrically via the fastener  24 . Similarly, the second terminal  23  and the power terminal board  27   b  are connected electrically via the fastener  24 . Those fasteners  24  connect the body  19  and the cover  21  mechanically as well. 
     Unlike a conventional lampholder, the above configuration of a lampholder of Embodiment 4 of the present invention eliminates the need to fasten the component of resin or ceramic, such as a body, and that of metal, such as a female screw shell, together. Therefore, many screws or the like are not necessary. As a result, the parts and the steps of tightening the screws or the like can be reduced, compared with the conventional lampholder. In addition, the mechanical connection between the body  19  and the cover  21  and the electrical connection between the receiving portion  20  and the lead wires  8   a,    8   b  can be made at the same time. Thus, the cost can be reduced and the productivity also can be increased further. 
     Embodiment 5 
     Next, a lampholder of Embodiment 5 of the present invention has the same configuration as that of a lampholder of Embodiment 1 of the present invention except that a receiving portion  4  and lead wires  8   a,    8   b  are connected electrically via metallic terminals  28 ,  29  that are made of copper or brass and embedded in the receiving portion  4 , as shown in FIG.  5 . 
     The metallic terminal  28  is in the form of a plate having a length of 27 mm, width of 5 mm to 7 mm, and thickness of 0.1 mm to 1.0 mm. The length of the embedded portion of the metallic terminal  28  in a first terminal  6  is 20 mm. On the other hand, the metallic terminal  29  is in the form of a plate having a length of 20 mm, width of 5 mm to 7 mm, and thickness of 0.1 mm to 1.0 mm and is bent to have an L shape. The length of the embedded portion of the metallic terminal  29  in a second terminal  7  is 13 mm. 
     The lead wires  8   a,    8   b  are connected electrically to the metallic terminals  28 ,  29 , respectively, by caulking. 
     Unlike a conventional lampholder, the above configuration of a lampholder of Embodiment 5 of the present invention eliminates the need to fasten the component of resin or ceramic, such as a body, and that of metal, such as a female screw shell, together. Therefore, many screws or the like are not necessary. As a result, the parts and the steps of tightening the screws or the like can be reduced, compared with the conventional lampholder. Thus, the reduction of cost as well as the improvement of productivity can be achieved. In addition, since the receiving portion  4  and the lead wires  8   a,    8   b  are connected electrically via the metallic terminals  28 ,  29 , the operation of connecting the receiving portion  4  and the lead wires  8   a,    8   b  can be performed easily. 
     In particular, the metallic terminal  29  is bent to have an L shape, thereby preventing it from slipping off the receiving portion  4  (the second terminal  7 ). 
     Example 6 
     Next, a lampholder of Embodiment 6 of the present invention includes a body  30 , a first terminal  31 , a central contact spring  32 , and a cover  5 , as shown in FIG.  6 . The body  30  is made of insulating resin and is in the form of a cylinder with the bottom, having a total length of 35 mm, outer diameter of 35 mm, and inner diameter of 30 mm. The first terminal  31  is made of conductive resin and provided on the inner surface of the body  30 . Also, the first terminal  31  has an internal thread  31   a  on the inner surface, into which a shell (not shown) of a cap (not shown), having an external thread, is screwed to establish the electrical connection between them. The central contact spring  32  is made of copper or brass, has an L shape, length of 32 mm, width of 5 mm to 7 mm, and thickness of 0.2 mm to 1.0 mm, and is connected electrically to an eyelet (not shown) at the end of the cap. The cover  5  has a height of 15 mm and outer diameter of 35 mm, and is provided on a bottom  30   a  of the body  30 . 
     The body  30  and the first terminal  31  are formed as an integral component. 
     The cover  5  is connected to the body  30  by engaging a concavity  5   a  at the end of the cover  5  with a convexity  30   b  at the bottom  30   a  of the body  30 . 
     A metallic terminal  28  in the form of a plate having a length of 27 mm, width of 5 mm to 7 mm, and thickness of 0.1 mm to 1.0 mm is embedded in the first terminal  31  to establish the electrical connection between them. The length of the embedded portion of the metallic terminal  28  is 20 mm. Also, the metallic terminal  28  is connected electrically to a lead wire  8   a  by caulking, the lead wire  8   a  being drawn from a hole  5   b  in the center of the cover  5  to the outside of the lampholder. In other words, the lead wire  8   a  and the first terminal  31  are connected electrically via the metallic terminal  28 . 
     The bottom  30   a  of the body  30  holds the central contact spring  32 , which penetrates the bottom  30   a.  One end of the central contact spring  32  is connected electrically to a lead wire  8   b  by caulking. When a cap is inserted in the lampholder, the other end of the central contact spring  32  is pushed toward the cover  5  into contact with a projection  30   c  at the center of the bottom  30   a  of the body  30  and is connected electrically to the eyelet of the cap. In this case, force acts to move the other end of the central contact spring  32  back to the cap side, so that the electrical connection between the central contact spring  32  and the eyelet can be established reliably. 
     Unlike a conventional lampholder, the above configuration of a lampholder of Embodiment 6 of the present invention eliminates the need to fasten the component of resin or ceramic, such as a body, and that of metal, such as a female screw shell, together. Therefore, many screws or the like are not necessary. As a result, the parts and the steps of tightening the screws or the like can be reduced, compared with the conventional lampholder. Thus, the reduction of cost as well as the improvement of productivity can be achieved. In addition, the central contact spring  32  of metal is used to make the electrical connection with the eyelet, thereby decreasing contact failure and increasing reliability. 
     Embodiment 7 
     Next, a lampholder of Embodiment 7 of the present invention includes a body  33 , a first terminal  34 , a central contact spring  35 , and a cover  5 , as shown in FIG.  7 . The body  33  is made of insulating resin and is in the form of a cylinder with the bottom, having a total length of 35 mm, outer diameter of 35 mm, and inner diameter of 30 mm. The first terminal  34  is made of conductive resin and provided on the inner surface of the body  33 . Also, the first terminal  34  has an internal thread  34   a  on the inner surface, into which a shell (not shown) of a cap (not shown), having an external thread, is screwed to establish the electrical connection between them. The central contact spring  35  is made of copper or brass, has an L shape, length of 25 mm, width of 5 mm to 7 mm, thickness of 0.2 mm to 1.0 mm, and is connected electrically to an eyelet (not shown) at the end of the cap. The cover  5  has a height of 15 mm and outer diameter of 35 mm, and is provided on the side of a bottom  33   a  of the body  33 . 
     The body  33  and the first terminal  34  are formed as an integral component. 
     The cover  5  is connected to the body  33  by engaging a concavity  5   a  at the end of the cover  5  with a convexity  33   b  at the bottom  33   a  of the body  33 . 
     A metallic terminal  36  in the form of a plate having a length of 25 mm, width of 5 mm to 7 mm, and thickness of 0.1 mm to 1.0 mm is embedded in the first terminal  34  to establish the electrical connection between them. The length of the embedded portion of the metallic terminal  36  is 18 mm. A pressure connector  37   a,  connected to a lead wire  8   a,  is fastened and electrically connected to the metallic terminal  36  with a fastener  38   a  composed of a screw. 
     The bottom  33   a  of the body  33  holds the central contact spring  35 , which penetrates the bottom  33   a.  A pressure connector  37   b,  connected to a lead wire  8   b,  is fastened and electrically connected to the central contact spring  35  with a fastener  38   b  composed of a screw. 
     In FIG. 7, reference numeral  39  indicates a hole for screws. 
     Unlike a conventional lampholder, the above configuration of a lampholder of Embodiment 7 of the present invention eliminates the need to fasten the component of resin or ceramic, such as a body, and that of metal, such as a female screw shell, together. Therefore, many screws or the like are not necessary. As a result, the parts and the steps of tightening the screws or the like can be reduced, compared with the conventional lampholder. Thus, the reduction of cost as well as the improvement of productivity can be achieved. In addition, the central contact spring  35  of metal is used to make the electrical connection with an eyelet, thereby decreasing contact failure and increasing reliability. Moreover, the lead wires  8   a,    8   b  can be removed from the lampholder easily, which facilitates the replacement of damaged parts caused, e.g., by disconnection of the lead wires  8   a,    8   b.    
     Embodiment 8 
     Next, a lampholder of Embodiment 8 of the present invention includes a body  30 , a first terminal  31 , a central contact spring  40 , and a cover  41 , as shown in FIG.  8 . The body  30  is made of insulating resin and is in the form of a cylinder with the bottom. The first terminal  31  is made of conductive resin and provided on the inner surface of the body  30 . Also, the first terminal  31  has an internal thread  31   a  on the inner surface, into which a shell (not shown) of a cap (not shown), having an external thread, is screwed to establish the electrical connection between them. The central contact spring  40  is made of copper or brass, has an L shape, length of 30 mm, width of 5 mm to 7 mm, and thickness of 0.2 mm to 1.0 mm, and is connected electrically to an eyelet (not shown) at the end of the cap. The cover  41  has a height of 15 mm and outer diameter of 30 mm, and is provided on a bottom  30   a  of the body  30 . 
     The body  30  and the first terminal  31  are formed as an integral component. 
     The body  30  is connected to the cover  41  by engaging a convexity  30   b  at the bottom  30   a  of the body  30  with a concavity  41   a  at the end of the cover  41 . 
     A metallic terminal  42  in the form of a plate having a length of 27 mm, width of 5 mm to 7 mm, and thickness of 0.1 mm to 1.0 mm is embedded in the first terminal  31  to establish the electrical connection between them. The length of the embedded portion of the metallic terminal  42  is 20 mm. 
     The bottom  30   a  of the body  30  holds the central contact spring  40 , which penetrates the bottom  30   a.    
     Two clip terminals  43   a,    43   b  are embedded in the cover  41  on the inner surface thereof. One clip terminal  43   a  clips the end of the metallic terminal  42 . Similarly, the other clip terminal  43   b  clips the end of the central contact spring  40 . 
     Each of two lead wires  8   a,    8   b,  drawn from a hole  41   b  in the center of the cover  41  to the outside of the lampholder, has a pressure connector  44  at the end thereof. The pressure connectors  44  are connected electrically to the clip terminals  43   a,    43   b,  respectively, e.g., by screws  45  or the like. 
     In FIG. 8, reference numeral  46  indicates a hole for screws. 
     Unlike a conventional lampholder, the above configuration of a lampholder of Embodiment 8 of the present invention eliminates the need to fasten the component of resin or ceramic, such as a body, and that of metal, such as a female screw shell, together. Therefore, many screws or the like are not necessary. As a result, the parts and the steps of tightening the screws or the like can be reduced, compared with the conventional lampholder. Thus, the reduction of cost as well as the improvement of productivity can be achieved. In addition, the central contact spring  40  of metal is used to make the electrical connection with the eyelet, thereby decreasing contact failure and increasing reliability. Moreover, the first terminal  31  and the central contact spring  40  can be connected electrically to the lead wires  8   a,    8   b  easily. 
     As described in each of the embodiments, the receiving portions  4 ,  10 , and  20  to be connected to a cap, including the first terminals  6 ,  11 ,  22 ,  31 , and  34  and the second terminals  7 ,  12 , and  23 , are made of conductive resin. Thus, compared with the conventional one made of metal, various means for connecting, e.g., the receiving portion to the lead wires  8   a,    8   b  can be employed. This can facilitate handling and prevent corrosion, such as rust. 
     In the above embodiments, the lampholder for the E-type cap  2  of the bulb-shaped fluorescent lamp  1  is described. However, the present invention can be applied to the E-type cap or B-type cap of a general incandescent lamp, a high-pressure discharge lamp, or the like. 
     The invention may be embodied in other forms without departing from the spirit or essential characteristics thereof. The embodiments disclosed in this application are to be considered in all respects as illustrative and not limiting. The scope of the invention is indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein.

Technology Classification (CPC): 7