Abstract:
A lamp tube switching circuit includes a first connector and a second connector for connecting either an LED lamp tube or a fluorescent type lamp tube, a switch module being a mechanical switch including first, second and third switches, a starter and ballast. Each of the first and second switches has a static terminal for connecting with a power supply, and four dynamic terminals for selectively connecting with the static terminal thereof. Different circuits can be configured by adjusting the connection between the static and dynamic terminals, wherein each circuit can drive a selected type of lamp tube to generate light.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Related subject matter is disclosed in co-pending U.S. patents application with an Ser. No. 13/215,208 and a title of LAMP TUBE SWITCHING CIRCUIT, and an Ser. No. 13/215,210 and a title of LAMP TUBE SWITCHING CIRCUIT AND METHOD THEREOF, which have the same assignees as the current application and were concurrently filed. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to switching circuits and, particularly, to a switching circuit for different types of lamp tubes. 
     2. Description of the Related Art 
     LEDs are widely used due to their advantageous characteristics. However, 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, they have to replace the holders as well. 
     Therefore, there is room for improvement within the art. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       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 switching circuit. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
         FIG. 1  is a circuit diagram of a lamp tube switching circuit in accordance with an exemplary embodiment. 
         FIG. 2  is a state diagram of a switch module when different types of lamp tubes are connected to the lamp tube switching circuit of  FIG. 1 . 
         FIG. 3  is a schematic view of the switch module of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , a lamp tube switching circuit  1  includes a ballast  10 , a starter  11 , a first connector  12   a  and a second connector  12   b  for connecting a lamp tube  2 , and a power port  14  for connecting a power supply  15 . The circuit  1  further includes a switch module  3 , 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  3  includes at least two switches  3   a  and  3   b . A user may switch each of the at least two switches  3   a  and  3   b  between “on” and “off”, to form a plurality of combinations of the states of the at least two switches  3   a  and  3   b  for driving circuits correspondingly to the LED type lamp tube and the fluorescent type lamp tube. The plurality of combinations may be marked up on a surface of an electronic device equipped with the switching circuit  1  for users to operate the switch module  3 . Users can operate the switch module  3  to turn on several of the at least two switches  3   a  and  3   b  and turn off the remaining to form a combination of the states of the at least two switches  3   a  and  3   b  according to the type of the lamp tube selected, to form a drive circuit corresponding to the type of the lamp tube  2 . 
     In the embodiment, the switch module  3  includes switches  3   a ,  3   b , and  3   c , and each of the switches  3   a ,  3   b  and  3   c  includes a static terminal and four dynamic terminals. The switch module  3  may be a mechanical switch module. The first connector  12   a  includes a first port  121  and a second port  122 , the second connector  12   b  includes a third port  123  and a fourth port  124 . 
     The static terminal  3   a - 0  of the switch  3   a  is connected to the positive terminal  150  of the power supply  15 , the static terminal  3   b - 0  of the switch  3   b  is connected to the negative terminal  151  of the power supply  15 , and the static terminal  3   c - 0  of the switch  3   c  is connected to the second port  122 . 
     A dynamic terminal  3   a - 2  of the switch  3   a  is connected to a first terminal of the ballast  10 , and a second terminal of the ballast  10  and dynamic terminals  3   a - 1  and  3   a - 4  of the switch  3   a  are connected to the third port  123 . The dynamic terminals  3   b - 1  and  3   b - 3  of the switch  3   b  and a second terminal of the starter  11  are connected to the fourth port  124 . The dynamic terminals  3   b - 2  and  3   b - 4  of the switch  3   b  and the dynamic terminal  3   a - 3  of the switch  3   a  are connected to the first port  121 . A first terminal of the starter  11  is connected to the dynamic terminal  3   c - 2  of the switch  3   c.    
       FIG. 2  illustrates a state diagram of the switch module  3  when different types of lamp tubes  2  are connected to the circuit  1 . In this diagram, “1” is defined to be the “on” state of the at least two switches, and “0” is defined to be the “off” state of the at least two switches. Taking a first type of lamp tube as an example which is an LED lamp tube, and the first type of the lamp tube includes two conductive pins mounted on an end of the lamp tube, and two insulation pins mounted on the other end of the lamp tube. “NC” corresponds to the insulation pin. When a lamp tube of the first type is needed to be connected to the circuit  1 , users operate the dynamic terminal  3   a - 1  to connect to the static terminal  3   a - 0 , and operate the dynamic terminal  3   b - 1  to connect to the static terminal  3   b - 0 , and turn off the other dynamic terminals of the switches  3   a  and  3   b  and turn off the switch  3   c , to form a combination of the switches  3   a ,  3   b  and  3   c  which is appropriate for the first type of lamp tube. Thus, when the lamp tube of the first type is connected to the circuit  1 , the two conductive pins are connected to the positive terminal  150  and the negative terminal  151  of the power supply  15  via the third port  123  and the fourth port  124  respectively, and the two insulation pins are connected to the first port  121  and the second port  122 . Thus, the drive circuit corresponding to the first type of lamp tube  2  is formed, and the lamp tube  2  can be driven to light. When any one of the second, third, fourth, and fifth type of lamp tube is needed to be connected in the switching circuit  1 , the operation is the same as the above description. 
     Taking a sixth type tube, namely a fluorescent tube, as an example, two conductive pins are mounted on each end of the fluorescent tube. When the fluorescent tube is connected to the circuit  1 , users operate the dynamic terminal  3   a - 2  to connect to the static terminal  3   a - 0 , and operate the dynamic terminal  3   b - 2  to connect to the static terminal  3   b - 0 , and operate the dynamic terminal  3   c - 2  to connect to the static terminal  3   c - 0 , and turn off the other dynamic terminals of the three switches  30   a ,  30   b ,  30   c . 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 the 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, a drive circuit corresponding to a fluorescent tube is formed, and the fluorescent tube can be driven to light. 
     In the embodiment, the switching circuit  1  further includes a fuse  13  connected between the positive terminal  150  of the power supply  15  and the switch module  3 , preventing damage to the circuit  1  from short circuits. 
       FIG. 3  illustrates a schematic view of the switch module  3 . The switch module  3  includes a main body  30 , a sliding member  31 , and a number of contact modules  32  all arranged on a top surface of the main body  30 . The main body  30  is substantially disc-shaped. The sliding member  31  includes an axial post  310  and a moveable arm  311  with one end rotatably connected to the axial post  310 . The axial post  310  is secured to the centre of the surface of the main body  30 . The moveable arm  311  is suspended above the surface of the main body  30 . Three conductive protrusions  312   a ,  312   b , and  312   c  protrude from the bottom surface of the moveable arm  311  and look down on the surface of the main body  30 . The protrusion  312   a ,  312   b , and  312   c  are connected to the positive terminal  150 , the negative terminal  151  and the first connector  12   a , respectively. In the embodiment, the protrusion  312   a  is connected to the positive terminal  150 , the protrusion  312   b  is connected to the negative terminal  151 , and the protrusion  312   c  is connected to the second port  122 . 
     The contact modules  32  are disposed on the top surface of the main body  30 , and each contact module  32  includes at least two contact elements arranged radially along the main body  30 . The contact elements of each contact module  32  are respectively connected to the dynamic terminals of the switches  3   a ,  3   b , and  3   c . The at least two contact elements are connected to the protrusions  312   a ,  312   b , and  312   c , to form a drive circuit correspondingly to the selected lamp tube of the LED type lamp tubes and the fluorescent type lamp tube when the conductive protrusions  312   a ,  312   b ,  312   c  of the moveable arm  311  make contact with the at least two contact elements. In this embodiment, there are six contact modules  32 , where each of five contact modules  32  includes two contact elements used for creating a drive circuit suitable for one of the LED lamp tubes, and the remaining one contact module  32  includes three contact elements used for creating a drive circuit suitable for a fluorescent tube. In the embodiment, an icon  33  is positioned next to each of the contact modules  32  for indicating the function of each contact module  32  in respect to the LED type lamp tubes or the fluorescent type lamp tube. 
     Taking the first type of lamp tube as an example, the contact module  32  corresponding to the first type of lamp tube includes two contact elements  32   a  and  32   b , and the contact element  32   a  is connected to the dynamic terminal  3   a - 1 , and the contact element  32   b  is connected to the dynamic terminal  3   b - 1 . When the moveable arm  310  makes contact with the contact module  32 , the protrusions  312   a  and  312   b  formed on the moveable arm  312  connect to the contact elements  32   a  and  32   b  respectively, and thereby the dynamic terminal  3   a - 1  is connected to the static terminal  3   a - 0 , and the dynamic terminal  3   b - 1  is connected to the static terminal  3   b - 0 . Thus, when a lamp tube  2  of the first type is connected to the circuit  1 , the two conductive pins are connected to the positive terminal  150  and the negative terminal  151  of the power supply  15  via the third port  123  and the fourth port  124  respectively, and the two insulation pins are connected to the first port  121  and the second port  122 . 
     It is understood that the present disclosure may be embodied in other forms without departing from the spirit thereof. Thus, 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.