Patent Publication Number: US-2011049981-A1

Title: Electric Shock Proof Socket Circuit

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to a socket circuit, and more particularly to an electric shock proof socket circuit. 
     2. The Related Art 
     In a conventional socket, the conductive pieces are adjacent to the inserting holes. When the pins or the prongs of a plug are inserted into the corresponding inserting holes of the socket, they contact the conductive pieces to form an electrical connection therebetween. However, no stoppers are provided between the conductive pieces and the pins, so that a dangerous condition may occur. If a child inserts an undesired object into the inserting hole, the child may possibly get an electric shock. So an improved socket is provided with an electric shock proof protector. The protector is achieved with a helical-type compressible spring. However, because the space in the socket is small, it is difficult to insert the spring in the socket. In addition, the spring often has a problem of elastic fatigue, thereby reduces the effectiveness of the protector. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide an electric shock proof socket circuit including a power supply module, a detecting module and a switching module. The power supply module is adapted for stepping down and rectifying an external input voltage and then providing the step-down and rectified voltage to the detecting module and the switching module. The detecting module includes a light-emitting unit and a light-receiving unit. The light-emitting unit is used for emitting light to the light-receiving unit. Whether the light emitted from the light-emitting unit being received by the light-receiving unit or not makes the detecting module send corresponding control signals. The switching module controls the power output of the socket circuit according to the control signals sent from the detecting module. 
     As described above, the electric shock proof socket circuit of the present invention utilizes the detecting module to emit-receive the light so as to drive the switching module to control the power output of the socket for preventing an electric shock danger. So the electric shock proof socket circuit of the present invention has the advantages of security and convenience. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be apparent to those skilled in the art by reading the following description, with reference to the attached drawings, in which: 
         FIG. 1  is a circuitry of an electric shock proof socket circuit according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With reference to  FIG. 1 , an electric shock proof socket circuit  100  of the present invention includes a power supply module  1 , a detecting module  2  and a switching module  3 . The power supply module  1  includes a step-down circuit  11 , a rectifying and filtering circuit  12  and a voltage-regulating circuit  13 . The step-down circuit  11  is connected with a live wire input Lin for getting an input voltage therefrom and further has a step-down function to the input voltage. The step-down circuit  11  includes a step-down capacitor C 1  and a first resistor R 1  parallel-connected with the step-down capacitor C 1 . 
     The rectifying and filtering circuit  12  includes a rectifier connected with the step-down circuit  11  for rectifying the step-down voltage from the step-down circuit  11 , and a filter connected with the rectifier for filtering the rectified voltage by the rectifier. In this embodiment, the rectifier is a bridge rectifier composed of a first rectifying diode BD 1 , a second rectifying diode BD 2 , a third rectifying diode BD 3  and a fourth rectifying diode BD 4 , and the filter is a filtering capacitor C 2 . The cathode of the first rectifying diode BD 1  and the anode of the second rectifying diode BD 2  are connected with each other and further connected with the step-down circuit  11 . The cathode of the third rectifying diode BD 3  and the anode of the fourth rectifying diode BD 4  are connected with each other and further connected with a neutral wire input Nin. The cathodes of the second and fourth rectifying diodes BD 2 , BD 4  are connected with each other and the connection point thereof is defined as a first connecting terminal P 1 . The anodes of the first and third rectifying diodes BD 1 , BD 3  are connected with each other and the connected point thereof is defined as a second connecting terminal P 2  connected to ground. The positive electrode of the filtering capacitor C 2  is connected with the first connecting terminal P 1 , and the negative electrode thereof is connected with the second connecting terminal P 2 . 
     The voltage-regulating circuit  13  includes two voltage-regulating diodes D 1 , D 2  parallel-connected with each other with the cathodes connected to the first connecting terminal P 1  through a second resistor R 2  and the anodes connected with the second connecting terminal P 2  so as to regulate the rectified and filtered voltage by the rectifying and filtering circuit  12  for the detecting module  2  and the switching module  3 . 
     The detecting module  2  includes a light-emitting unit  21  including three parallel-connected light-emitting elements E 1 ˜E 3 , and a light-receiving unit  22  including three parallel-connected photosensitive elements T 1 ˜T 3 . One terminal of the light-emitting unit  21  is connected to the first connecting terminal P 1  through a third resistor R 3  and the second resistor R 2 , and the other terminal thereof is connected with the second connecting terminal P 2  of the rectifying and filtering circuit  12 . One terminal of the light-receiving unit  22  is connected to the first connecting terminal P 1  through a fourth resistor R 4  and the second resistor R 2 , and the other terminal thereof is connected to the second connecting terminal P 2  through a fifth resistor R 5 . The three photosensitive elements T 1 ˜T 3  are located to one-to-one face the corresponding light-emitting elements E 1 ˜E 3 , and both each of the photosensitive elements T 1 ˜T 3  and the corresponding one of the light-emitting elements E 1 ˜E 3  are located at two opposite sides of a corresponding inserting hole of a socket (not shown) with the electric shock proof socket circuit  100  therein. In the embodiment, the light-emitting elements E 1 ˜E 3  are respectively an infrared emitter and the photosensitive elements T 1 ˜T 3  are respectively a photosensitive triode, wherein the connection and the disconnection of the photosensitive triode are controlled according to whether the light from the corresponding infrared emitter can be received or not. 
     The switching module  3  includes a first switch Q 1 , a second switch Q 2  and an inductance switch S 1 . In the embodiment, the first switch Q 1  and the second switch Q 2  are respectively a transistor. The collector of the second switch Q 2  is on one hand connected to the first connecting terminal P 1  of the bridge rectifier through a sixth resistor R 6  and the second resistor R 2 , and on the other hand, connected to the emitter thereof through a seventh resistor R 7 . The base of the second switch Q 2  is connected at the connection location of the light-receiving unit  22  and the fifth resistor R 5 , and the emitter thereof is further directly connected with the second connecting terminal P 2  of the bridge rectifier. The base of the first switch Q 1  is connected with the collector of the second switch Q 2 , the emitter thereof is connected with the second connecting terminal P 2  of the bridge rectifier, and the collector thereof is connected to the second resistor R 2  through a directive diode D 3 , wherein the directive diode D 3  can guide a backflow current produced by the disconnection of the first switch Q 1  so as to protect the first switch Q 1 . 
     In the embodiment, the inductance switch S 1  is an electromagnetic relay composed of a control system S 11  and a switch system S 12 , wherein the switch state of the switch system S 12  is controlled according to whether there is a voltage on the control system S 11  or not. The control system S 11  is parallel-connected to the directive diode D 3 . One terminal of the switch system S 12  is connected with the live wire input Lin, and the other terminal thereof is connected to the neutral wire input Nin successively through an eighth resistor R 8  and an indicating element, wherein the indicating element is used to indicate the switch state of the switch system S 12 . In the embodiment, the indicating element is a light-emitting diode D 4 , when the inductance switch S 1  is connected, the light-emitting diode D 4  is lighted. The connection location of the switch system S 12  and the eighth resistor R 8  is drawn forth as a live wire output Lout, and the neutral wire input Nin is also acted as a neutral wire output Nout. When pins or prongs of an external plug are respectively inserted into the inserting holes of the socket, the pins or prongs are electrically connected with the corresponding live wire output Lout and the neutral wire output Nout. 
     When the socket is not in use, namely all of the inserting holes of the socket are not inserted with the pins of the plug or undesired objects, the light emitted by the light-emitting elements E 1 ˜E 3  is respectively received by the corresponding photosensitive elements T 1 ˜T 3  so that makes the light-receiving unit  22  connected. So a high-voltage signal is transmitted to the base of the second switch Q 2  to make the second switch Q 2  connected and accordingly the first switch Q 1  disconnected. As a result, the inductance switch S 1  is in a disconnected state due to the status of no voltage thereon. So there is no power to be output by the live wire output Lout. 
     When the number of the pins of the plug is less than three, or there are less than three undesired objects inserted into the inserting holes of the socket, namely if only there is one of the inserting holes without being inserted with the pin of the plug or the undesired object, the light emitted by the exposed one of the light-emitting elements E 1 ˜E 3  can be received by the corresponding exposed photosensitive element T 1 /T 2 /T 3  so as to make the light-receiving unit  22  connected that can make a high-voltage signal transmitted to the base of the second switch Q 2  to make the second switch Q 2  connected and accordingly the first switch Q 1  disconnected. So the inductance switch S 1  is in the disconnected state due to the status of no voltage thereon, and there is still no power to be output by the live wire output Lout. 
     When the pins of the plug are wrongly inserted into the inserting holes of the socket, or each of the inserting holes of the socket is inserted with the undesired object, but if only there is the light from any of the light-emitting elements E 1 ˜E 3  unobstructed completely by the pin or the undesired object, the corresponding photosensitive element T 1 /T 2 /T 3  can receive the unobstructed light to make the light-receiving unit  22  connected and further make the second switch Q 2  connected and accordingly the first switch Q 1  disconnected. So the inductance switch S 1  is still in the disconnected state due to the status of no voltage thereon, and there is still no power to be output by the live wire output Lout. 
     When each of the inserting holes of the socket is rightly inserted with the corresponding pin of the plug, the light emitted by the light-emitting elements E 1 ˜E 3  is completely obstructed by the corresponding pins of the plug so that makes the light-receiving unit  22  disconnected. So a low-voltage signal is transmitted to the base of the second switch Q 2  to make the second switch Q 2  disconnected so that there is a current flew through the seventh resistor R 7  and the first switch Q 1  is connected to produce voltage on the control system S 11  of the inductance switch S 1 . Therefore, the switch system S 12  of the inductance switch S 1  is connected to make the live wire output Lout output power for the plug. 
     As described above, the electric shock proof socket circuit  100  of the present invention utilizes the detecting module  2  to emit-receive the light so as to drive the switching module  3  to control the power output of the socket for preventing an electric shock danger. So the electric shock proof socket circuit  100  of the present invention has the advantages of security and convenience.