Abstract:
A lamp tube switch circuit includes a first connector and a second connector for connecting a lamp tube, a power supply, a switch module including at least six switches connected between the power port, the first connector and second connector, a detecting unit connected between the first connector and the second connector, a control unit, a ballast and a starter. The detecting unit detects impedances between the pins of the lamp tube to determine the type of the lamp tube. The control unit is connected to the detecting unit, and operated to have some of the switches to turn one and the others to turn off whereby a drive circuit is formed enabling power from the power supply to flow through the lamp tube to make the lamp tube to generate light.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    Related subject matter is disclosed in co-pending U.S. patents application with an Attorney Docket Number US39867 and a title of LAMP TUBE SWITCH CIRCUIT, and an Attorney Docket Number US39869 and a title of LAMP TUBE SWITCH CIRCUIT, which have the same assignees as the current application and were concurrently filed. 
       BACKGROUND 
       [0002]    1. Technical Field 
         [0003]    The present disclosure relates to switch circuits and, particularly, to a switch circuit for different types of lamp tubes and a method thereof. 
         [0004]    2. Description of the Related Art 
         [0005]    LEDs are widely used but conventional lamp holders, for example fluorescent lamp holders, cannot be used to hold LED lamps, and also, LED lamp holders cannot be used to hold fluorescent lamps. Therefore, if users want to replace a fluorescent lamp with an LED lamp or replace an LED lamp with a fluorescent lamp, they have to replace the holder as well. 
         [0006]    Therefore, there is room for improvement within the art. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of a lamp tube switch circuit and a method thereof. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
           [0008]      FIG. 1  is a circuit diagram of a lamp tube switch circuit in accordance with an exemplary embodiment. 
           [0009]      FIG. 2  is a state diagram of the button module when different types of lamp tubes are selected for connection to the lamp tube switch circuit of  FIG. 1 . 
           [0010]      FIG. 3  is a flowchart of a method for switching different lamp tubes in accordance with an exemplary embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0011]    Referring to  FIG. 1 , a lamp tube switch circuit  1  includes a ballast  10 , a starter  11 , a first connector  12   a  and a second connector  12   b  for connecting to a lamp tube  2 , and a power port  14  for connecting a power supply  15 . The circuit  1  further includes a switch module  13 , a detecting unit  16 , and a control unit  17 . The control unit  17  is connected between the detecting unit  16  and the switch module  13  to manipulate the detecting unit  16  and receive signals from the detecting unit  16 . Furthermore, the control unit manipulates the switch module  13  according to the received signals. The switch module  13  is connected between the power port  14 , the first connector  12   a  and the second connector  12   b.  The ballast  10  and the starter  11  are connected between the switch module  13  and the second connector  12   b.  The switch module  13  includes at least two independent switches. The detecting unit  16  is connected between the first connector  12   a  and the second connector  12   b,  for detecting the impedance across the pins of the lamp tube  2 . The relationship among types of lamp tubes, the impedances between the pins of each end pair, and the states of the at least two switches is predetermined. The control unit  17  may turn on several of the at least two switches, and must turn off the remaining incompatible switches according to the impedance detected by the detecting unit  16  and the predetermined relationships, so as to form a drive circuit which corresponds and is appropriate for the lamp tube  2  which is being used. 
         [0012]    In the embodiment, the switch module  13  includes switches  131 ,  132 ,  133 ,  134 ,  135 ,  136 , and  137 . The switches  131 ,  132 ,  133 ,  134 ,  135 ,  136 , and  137  are all relays. The control unit  17  may switch on or switch off the switches  131 ,  132 ,  133 ,  134 ,  135 ,  136 , and  137  or any of them. The first connector  12   a  includes a first port  121  and a second port  122 , and the second connector  12   b  includes a third port  123  and a fourth port  124 . 
         [0013]    A first end of each of the switches  131 ,  132 ,  133  and  135  is connected to a positive terminal  150  of the power supply  15 , and a second end of the switch  132  is connected to a first end of the ballast  10 . A second end of the ballast  10  and a second end of the switch  131  are connected to the third port  123 . First ends of the switches  134  and  136  are connected to a negative terminal  151  of the power supply  15 . Second ends of the switches  133  and  134  are connected to the first port  122 , and a second end of the switch  136  is connected to the fourth port  124 . The starter  11  is connected between a second end of the switch  137  and the fourth port  124 . 
         [0014]    The detecting unit  16  includes a detecting module  160 . A pair of ports  1601  and  1602  connect to one end of the detecting module  160  and a pair of ports  1603  and  1604  connect to the other end of the module  160 . In the embodiment, the detecting unit  16  further includes four switches  161 ,  162 ,  163 , and  164 . The switch  161  is connected between the second port  122  and the port  1601 , the switch  162  is connected between the switch  134  and the port  1602 , the switch  163  is connected between the fourth port  124  and the port  1603 , and the switch  164  is connected between the third port  123  and the port  1604 . When the lamp tube  2  is connected to the switching circuit  1 , the control unit  17  turns on the switches  161 ,  162 ,  163 , and  164 . A mechanical switch (not shown) can be included and positioned for users to operate the switch module  13 . The detecting module  160  detects the impedance between each pin of each end pair of pins of the lamp tube  2 . The control unit  17  turns on and turns off the at least two switches according to the relationship. In an alternative embodiment, the switches  161 ,  162 ,  163 , and  164  can be controlled manually. 
         [0015]      FIG. 2  illustrates a state diagram of the impedances of the pins of the lamp tube when different types of lamp tubes are connected to the circuit  1 . The diagram records predetermined relationships among types of lamp tubes, the impedances between end pins of the lamp tubes, and the states of the at least two switches. In this diagram, logic “1” is defined to be the “on” state of the at least two switches, and logic “0” is defined to be the “off” state of the at least two switches. “+∞” means the value of a resistance is larger than 50 M ohm (R&gt;50 M ohm). The control unit  17  determines which type of lamp tube has been connected (or selected), and turns on and turns off the at least two switches according to the impedances of the pins as detected by the detecting module  160  and the relationships. Taking a first type of lamp tube as an example, which is an LED lamp tube, two conductive pins form the end pin pair on one end of the lamp tube, and two insulation pins form the end pin pair on the other end of the lamp tube. “NC” corresponds to the insulation pin. When the first type of lamp tube  2  is connected to the first connector  12   a  and the second connector  12   b,  the detecting module  160  detects the impedances between pins via the ports  1601 ,  1602 ,  1603 , and  1604 . For example, the detecting module  160  may detect the impedance between the pins connected to the first port  121  and the second port  122  via the port  1601  and the port  1602  respectively. The impedance between the two conductive pins is R, and the impedance between the other pair is “+∞” (shown in  FIG. 2 ). The control unit  17  determines the selected type of lamp tube according to the impedances detected by the detecting module  160 , and turns on or turns off the at least two switches of the switch module  13  according to the relationship. In the embodiment, the control unit  16  turns on the switches  131  and  136 , and turns off the switches  132 ,  133 ,  134 ,  135 , and  137 . Thus, when the first type of lamp tube  2  is connected to the circuit  1 , the two conductive pins are connected to the positive and negative terminals  150  and  151  via the third and fourth ports  123  and  124 , and the two insulation pins are connected to the first and second ports  121  and  122 . Thus, the drive circuit corresponding to and appropriate for the first type of lamp tube  2  is formed. 
         [0016]    Taking a sixth type tube, namely a fluorescent tube, as an example, two conductive pins are mounted on each end of the fluorescent tube. The impedances between the two pins mounted on each end of the fluorescent tube are about the same, and the impedances between the other two pins are about equal to “+∞” (shown in  FIG. 2 ). When the fluorescent tube is connected between the first connector  12   a  and the second connector  12   b,  the detecting module  160  detects the impedances between pins. The control unit  17  determines the selected or connected type of lamp tube according to the impedances detected by the detecting module  160 , and turns on and turns off the at least two switches of the switch module  13  according to the relationship. In the embodiment, the control unit  16  turns on the switches  132 ,  134  and  137 , and turns off the switches  131 ,  133 ,  135 , and  136 . Thus, when the fluorescent tube is connected to the switching circuit  1 , the conductive pin connected to the first port  121  is connected to the negative terminal  151  of the power supply  15 , and conductive pin connected to the second port  122  is connected to the positive terminal  150  of the power supply  15 , the conductive pins connected to the third port  123  and the fourth port  124  are connected between the ballast  11  and the starter  11 . Thus, the drive circuit corresponding to a fluorescent tube is formed, and the fluorescent tube can be driven to light. 
         [0017]      FIG. 3  is a flowchart of a method for switching different types of lamp tubes in accordance with an exemplary embodiment. 
         [0018]    In step S 31 , the lamp tube  2  is connected between the first connector  12   a  and the second connector  12   b.    
         [0019]    In step S 32 , the control unit  17  provides a control signal to turn on the switches  161 ,  162 ,  163 , and  164  of the detecting unit  16 , thus the lamp tube  2  is connected to the detecting module  160 . 
         [0020]    In step S 33 , the detecting module  160  detects the impedances between each two pins of the pins of the lamp tube  2 . 
         [0021]    In step S 34 , the control unit  17  determines the connected or selected type of lamp tube  2  according to the impedances detected by the detecting module  160  and according to the relationship. 
         [0022]    In step S 35 , the control unit  17  turns on or turns off the at least two switches of the switch module  13  according to the relationship. 
         [0023]    The present disclosure may be embodied in other forms without departing from the spirit thereof. The present examples and embodiments are to be considered in all respects as illustrative and not restrictive, and the disclosure is not to be limited to the details given herein.