Patent Document

This application claims the benefit of Taiwan patent application No. 095220244, filed on Nov. 17, 2006. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a two-end driven lamp controlling device and, in particular, to a two-end driven lamp controlling device for balancing the brightness of a liquid crystal display (LCD) backlight. 
   2. Descriptions of the Related Art 
   Refer to  FIG. 1 , which is a block diagram of a conventional two-end driven lamp controlling device. As shown, the conventional two-end driven lamp controlling device  1  has a DC power supply  12  disposed on one side of a plurality of lamps  11 , the DC power supply  12  is used for supplying DC power to a square wave switch  13 , the square wave switch  13  is used for receiving synchronous control signals input from a square wave controller  14  and providing starting transformers  15  with square wave signals and the starting transformers  15  is used for outputting signals such as to drive the lamps  11  in coordination with a plurality of capacitive elements  16 , so that the purpose for maintaining a homogenized brightness of the lamps  11  can be fulfilled. According to the block diagram shown in  FIG. 1 , there should be capacitors disposed at both ends of the lamp, for providing the lamp with sufficiently high voltage to keep the brightness from being inhomogeneous. However, the use of high voltage may cause a problem of voltage endurance, which would be hard to solve, and the use of too many capacitors may increase the cost largely so that a limited application would be present. 
   Refer to  FIG. 2 , which is a block diagram of another conventional two-end driven lamp controlling device. As shown, the conventional two-end driven lamp controlling device  1  has a DC power supply  12  disposed on one side of a plurality of lamps  11 , the DC power supply  12  is used for supplying DC power to a square wave switch  13 , the square wave switch  13  is used for receiving synchronous control signals input from a square wave controller  14  and providing starting transformers  15  numerously corresponding to the lamps  11  with square wave signals and the starting transformers  15  are used for outputting signals such as to drive the lamps  11 , so that the purpose for maintaining a homogenized brightness of the lamps  11  can be fulfilled. According to the block diagram shown in  FIG. 2 , there are starting transformers disposed at both ends of the lamp, which may keep the brightness from being inhomogeneous and solve the problem of voltage endurance. However, the use of so many starting transformers may increase the cost, so that a limited application would be present, also. 
   Therefore, the above-mentioned conventional techniques have still various shortcomings and, as it being not ideally designed, an improvement is in need. In view of this, the present inventor(s) has (have) set about the work of improvement and innovation and successfully developed the two-end driven lamp controlling device of the present invention through a long-term study and practice. 
   SUMMARY OF THE INVENTION 
   The primary objective of this invention is to provide a two-end driven lamp controlling device for balancing a plurality of lamps to fulfill the purpose for homogenizing the brightness of the lamps. 
   Another objective of this invention is to provide a two-end driven lamp controlling device that has advantages of increased stability of use, elongated lifetime of use, decreased cost, reduced size of transformers and saved space for set-up. 
   A two-end driven lamp controlling device for fulfilling the objectives of the present invention comprises a direct-current (DC) power supply, square wave switches, a square wave controller, a plurality of lamps, a plurality of starting transformers and a connecting transformer, wherein the plurality of starting transformers or the connecting transformer are disposed on the sides of the plurality of lamps and the square wave switches are connected to the sides of the plurality of starting transformers or the connecting transformer and to the DC power supply and can receive signals from the square wave controller. The present invention utilizes a circuitry design of a plurality of lamps, a plurality of starting transformers and a connecting transformer so as to make the brightness of the plurality of lamps effectively homogenized and balanced and, moreover, to solve the problem of high cost for conventional devices, which use too many components for maintaining the brightness of the lamps. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a block diagram of a conventional two-end driven lamp controlling device. 
       FIG. 2  is a block diagram of another conventional two-end driven lamp controlling device. 
       FIG. 3  is a circuit diagram of a first embodiment of the two-end driven lamp controlling device according to the present invention. 
       FIG. 4  is a circuit diagram of a second embodiment of the two-end driven lamp controlling device according to the present invention. 
       FIG. 5  is a circuit diagram of a third embodiment of the two-end driven lamp controlling device according to the present invention. 
       FIG. 6  is a circuit diagram of a forth embodiment of the two-end driven lamp controlling device according to the present invention. 
       FIG. 7  is a circuit diagram of a sixth embodiment of the two-end driven lamp controlling device according to the present invention. 
       FIG. 8A-8E  are schematic diagrams of the lamp impedance matching of the two-end driven lamp controlling device according to the present invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Refer to  FIG. 3 , which is a circuit diagram of a first embodiment of the two-end driven lamp controlling device according to the present invention. As shown, the conventional two-end driven lamp controlling device  2  comprises: 
   a DC power supply  22 , for outputting DC power to a square wave switch  23 ; 
   a square wave switch  23 , for receiving DC power from the DC power supply  22 , converting the DC power into AC power and then outputting the AC power to a plurality of starting transformers  25  and a commonly connective transformer  26 ; 
   a square wave controller  24 , for outputting control signals to the square wave switch  23 ; 
   a plurality of lamps  21 , the lamp  21  having an independent end and a commonly connective end for which the voltage phases are reverse to each other, wherein the commonly connective ends of the lamps  21  are commonly connected to a point that is further connected to at least one set of secondary coil of the commonly connective transformer  26  while the independent end of the lamp  21  is connected to at least one set of secondary coil of a corresponding one of the plurality of starting transformers  25 ; 
   a plurality of starting transformers  25 , the starting transformer  25  having at least one set of primary coil and at least one set of secondary coil, each set having two ends, wherein the at least one set of primary coil receives power signals from the square wave switch  23  while the at least one set of secondary coil, after voltage raising, has one end connected to the independent end of a corresponding one of the plurality of lamps  21  and the other one end connected to a reference ground level; and 
   a commonly connective transformer  26 , having at least one set of primary coil and at least one set of secondary coil, each set having two ends, wherein the at least one set of primary coil receives power signals from the square wave switch  23  while the at least one set of secondary coil, after voltage raising, has one end connected to the commonly connective ends of the plurality of lamps  21  and the other one end connected to a reference ground level. 
   Thus, the problem of high cost for conventional devices can be solved effectively. 
   Refer to  FIG. 4 , which is a circuit diagram of a second embodiment of the two-end driven lamp controlling device according to the present invention. As shown, the conventional two-end driven lamp controlling device  2  comprises: 
   a DC power supply  22 , for outputting DC power to a square wave switch  23 ; 
   a square wave switch  23 , for receiving DC power from the DC power supply  22 , converting the DC power into AC power and then outputting the AC power to a plurality of starting transformers  25  and a commonly connective transformer  26 ; 
   a square wave controller  24 , for outputting control signals to the square wave switch  23 ; 
   a plurality of lamps  21 , the lamp  21  having an independent end and a commonly connective end for which the voltage phases are reverse to each other, wherein the commonly connective ends of the lamps  21  are commonly connected to a point that is further connected to at least one set of secondary coil of the commonly connective transformer  26  while the independent end of the lamp  21  is connected to at least one set of secondary coil of a corresponding one of the plurality of starting transformers  25 ; 
   a plurality of starting transformers  25 , the starting transformer  25  having at least one set of primary coil and at least one set of secondary coil, each set having two ends, wherein the at least one set of primary coil receives power signals from the square wave switch  23  while the at least one set of secondary coil, after voltage raising, has one end connected to the independent end of a corresponding one of the plurality of lamps  21  and the other one end connected to one end of the at least one set of secondary coil of the connecting transformer  26  so as to form a serial loop; and 
   a commonly connective transformer  26 , having at least one set of primary coil and at least one set of secondary coil, each set having two ends, wherein the at least one set of primary coil receives power signals from the square wave switch  23  while the at least one set of secondary coil, after voltage raising, has one end connected to the commonly connective ends of the plurality of lamps  21  and the other one end connected to the one ends of the at least one sets of secondary coil of the starting transformers  25  so as to form a serial loop. 
   Thus, the problem of high cost for conventional devices can be solved effectively. 
   Refer to  FIG. 5 , which is a circuit diagram of a third embodiment of the two-end driven lamp controlling device according to the present invention. As shown, the conventional two-end driven lamp controlling device  2  comprises: 
   a DC power supply  22 , for outputting DC power to a square wave switch  23 ; 
   a square wave switch  23 , for receiving DC power from the DC power supply  22 , converting the DC power into AC power and then outputting the AC power to a plurality of starting transformers  25  and a commonly connective transformer  26 ; 
   a square wave controller  24 , for outputting control signals to the square wave switch  23 ; 
   a plurality of lamps  21 , the lamp  21  having an independent end and a commonly connective end for which the voltage phases are reverse to each other, wherein the commonly connective ends of the lamps  21  are commonly connected to a point that is further connected to at least one set of secondary coil of the commonly connective transformer  26  while the independent end of the lamp  21  is connected to at least one set of secondary coil of a corresponding one of the plurality of starting transformers  25 ; 
   a plurality of starting transformers  25 , the starting transformer  25  having at least one set of primary coil and at least one set of secondary coil, each set having two ends, wherein the at least one set of primary coil receives power signals from the square wave switch  23  while the at least one set of secondary coil, after voltage raising, has one end connected to the independent end of a corresponding one of the plurality of lamps  21  and the other one end connected to a reference ground level; and 
   a commonly connective transformer  26 , having at least one set of primary coil and at least one set of secondary coil, each set having two ends, wherein the at least one set of primary coil receives power signals from the square wave switch  23  while the at least one set of secondary coil, after voltage raising, has one end connected to one set of commonly connective ends of the plurality of lamps  21  and the other one end connected to the other one sets of commonly connective end of the plurality of lamps  21 . 
   Thus, the problem of high cost for conventional devices can be solved effectively. 
   Refer to  FIG. 6 , which is a circuit diagram of a forth embodiment of the two-end driven lamp controlling device according to the present invention. As shown, the conventional two-end driven lamp controlling device  2  comprises: 
   a DC power supply  22 , for outputting DC power to a square wave switch  23 ; 
   a square wave switch  23 , for receiving DC power from the DC power supply  22 , converting the DC power into AC power and then outputting the AC power to a plurality of starting transformers  25  and two commonly connective transformers  26 ; 
   a square wave controller  24 , for outputting control signals to the square wave switch  23 ; 
   a plurality of lamps  21 , the lamp  21  having an independent end and a commonly connective end for which the voltage phases are reverse to each other, wherein the commonly connective ends of the lamps  21  are commonly connected to a point that is further connected to at least one set of secondary coil of the commonly connective transformer  26  while the independent end of the lamp  21  is connected to at least one set of secondary coil of a corresponding one of the plurality of starting transformers  25 ; 
   a plurality of starting transformers  25 , the starting transformer  25  having at least one set of primary coil and at least one set of secondary coil, each set having two ends, wherein the at least one set of primary coil receives power signals from the square wave switch  23  while the at least one set of secondary coil, after voltage raising, has one end connected to the independent end of a corresponding one of the plurality of lamps  21  and the other one end connected to a reference ground level; and 
   two commonly connective transformers  26 , each having at least one set of primary coil and at least one set of secondary coil, each set having two ends, wherein the at least one set of primary coil receives power signals from the square wave switch  23  while the at least one set of secondary coil, after voltage raising, has one end connected to one end of the at least one set of secondary coil of the other one commonly connective transformer  26 , both further connected to a reference ground level, and the other one end connected to one of two sets of commonly connective ends of the plurality of lamps  21  so as to decrease the power of a single one of the commonly connective transformers  26  to achieve alternative polarization of the lamps  21 . 
   Thus, the problem of high cost for conventional devices can be solved effectively. 
   Refer to  FIG. 7 , which is a circuit diagram of a sixth embodiment of the two-end driven lamp controlling device according to the present invention. As shown, the conventional two-end driven lamp controlling device  2  comprises: 
   a DC power supply  22 , for outputting DC power to a square wave switch  23 ; 
   a square wave switch  23 , for receiving DC power from the DC power supply  22 , converting the DC power into AC power and then outputting the AC power to a plurality of starting transformers  25  and two commonly connective transformers  26 ; 
   a square wave controller  24 , for outputting control signals to the square wave switch  23 ; 
   a plurality of lamps  21 , the lamp  21  having an independent end and a commonly connective end for which the voltage phases are reverse to each other, wherein the plurality of lamps  21  are divided into two sets of which one set has the commonly connective ends thereof commonly connected to a point that is further connected to one end of at least one set of secondary coil of the commonly connective transformer  26  and the other one set has the commonly connective ends thereof commonly connected to another point that is further connected to the other one end of the at least one set of secondary coil of the commonly connective transformer  26  while the independent end of the lamp  21  is connected to at least one set of secondary coil of a corresponding one of the plurality of starting transformers  25 ; 
   a plurality of starting transformers  25 , the starting transformer  25  having at least one set of primary coil and at least one set of secondary coil, each set having two ends, wherein the at least one set of primary coil receives power signals from the square wave switch  23  while the at least one set of secondary coil, after voltage raising, has one end connected to the independent end of a corresponding one of the plurality of lamps  21  and the other one end connected to the independent end of another corresponding one of the plurality of lamps  21 ; and 
   two commonly connective transformers  26 , each having at least one set of primary coil and at least one set of secondary coil, each set having two ends, wherein the at least one set of primary coil receives power signals from the square wave switch  23  while the at least one set of secondary coil, after voltage raising, has one end connected to one end of the at least one set of secondary coil of the other one commonly connective transformer  26 , both further connected to a reference ground level, and the other one end connected to one of two sets of commonly connective ends of the plurality of lamps  21  so as to decrease the power of a single one of the commonly connective transformers  26  to achieve alternative polarization of the lamps  21 . 
   Thus, the problem of high cost for conventional devices can be solved effectively. 
   Refer to  FIG. 8A-8E , which are schematic diagrams of the lamp impedance matching of the two-end driven lamp controlling device according to the present invention. As shown, for the two-end driven lamp controlling device, to one end of a lamp  31 , a capacitive element  32  can be connected in series, which can be further connected to another electronic element ( FIG. 8A ); to each of the two ends of a lamp  31 , a capacitive element  32  can be connected in series, which can be further connected to other electronic elements ( FIG. 8B ); to each of the two ends of a lamp  31 , a capacitive element  32  can be connected in series, which can be further connected to reference ground levels ( FIG. 8C ); to each of the two ends of a lamp  31 , two capacitive elements  32  can be connected in parallel, which can be further connected to other electronic elements or reference ground levels, respectively ( FIG. 8D ); to each of the two ends of a lamp  31 , two capacitive elements  32  can be connected in series, which can be further connected to reference ground levels ( FIG. 8E ). Impedance matching can be achieved, thus. 
   The present invention provides a two-end driven lamp controlling device, as compared with conventional techniques, having the following advantages: 
   1. The two-end driven lamp controlling device can make the brightness of a plurality of lamps effectively homogenized and balanced. 
   2. The two-end driven lamp controlling device has advantages of increased stability of use, elongated lifetime of use, decreased cost, reduced size of transformers and saved space for set-up. 
   The above disclosure is related to the detailed technical contents and inventive features thereof. People skilled in this field may proceed with a variety of modifications and replacements based on the disclosures and suggestions of the invention as described without departing from the characteristics thereof. Nevertheless, although such modifications and replacements are not fully disclosed in the above descriptions, they have substantially been covered in the following claims as appended.

Technology Category: 5