Abstract:
A driving device provides output power to an illumination device including a plurality of filaments is provided. A first converting module converts input power into direct current (DC) power. The first converting module includes a pair of first input terminals receiving the input power and a pair of first output terminals coupled to a first node and a second node and outputting the DC power. A first capacitor is coupled between the first node and a third node. A second capacitor is coupled between the second and third nodes. The first clamping module is connected to a first specific capacitor in parallel. The first specific capacitor is the first capacitor or the second capacitor. A second converting module converts the DC power to generate the output power.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This Application claims priority of Taiwan Patent Application No. 104100487, filed on Jan. 8, 2015, the entirety of which is incorporated by reference herein. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The invention relates to a driving device, and more particularly to a driving device to light an illumination device. 
         [0004]    2. Description of the Related Art 
         [0005]    Illumination is a base requirement for people. In recent years, economic and trade activities and business activities are frequently held, and quality of home life is increased. The amount of electricity required for illumination is increased. Therefore, the power consumption of illumination is appreciable. Low-voltage, gas-discharge lamps are used widely. These lamps are referred to as fluorescent lamps. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    In accordance with an embodiment, a driving device provides output power to an illumination device comprising a plurality of filaments and comprises a first converting module, a first capacitor, a second capacitor, a first clamping module, and a second converting module. The first converting module converts input power into direct current (DC) power. The first converting module comprises a pair of first input terminals receiving the input power and a pair of first output terminals coupled to a first node and a second node and outputting the DC power. The first capacitor is coupled between the first node and a third node. The second capacitor is coupled between the second and third nodes. The first clamping module is connected to a first specific capacitor in parallel. The first specific capacitor is the first capacitor or the second capacitor. The second converting module converts the DC power to generate the output power. The second converting module comprises a second input terminal pair coupled to the first and second nodes and a second output terminal pair outputting the output power to turn on the illumination device. 
         [0007]    In accordance with another embodiment, an illumination system comprises a first illumination device, a first converting module, a first capacitor, a second capacitor, a first clamping module, and a second converting module. The first illumination device comprises a plurality of filaments. The first illumination device is turned on according to output power. The first converting module converts input power into direct current (DC) power. The first converting module comprises a pair of first input terminals receiving the input power and a pair of first output terminals coupled to a first node and a second node and outputting the DC power. The first capacitor is coupled between the first node and a third node. The second capacitor is coupled between the second and third nodes. The first clamping module is connected to a first specific capacitor in parallel. The first specific capacitor is the first capacitor or the second capacitor. The second converting module converts the DC power to generate the output power. The second converting module comprises a second input terminal pair coupled to the first and second nodes and a second output terminal pair outputting the output power to turn on the illumination device. 
         [0008]    A detailed description is given in the following embodiments with reference to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The invention can be more fully understood by referring to the following detailed description and examples with references made to the accompanying drawings, wherein: 
           [0010]      FIGS. 1 and 5  are schematic diagrams of exemplary embodiments of an illumination system, in accordance with some embodiments; 
           [0011]      FIGS. 2-3 and 6  schematic diagrams of exemplary embodiments of a driving device, in accordance with some embodiments; and 
           [0012]      FIG. 4  is a schematic diagram of an exemplary embodiment of a connection among a converting module, a preheating module and a load, in accordance with some embodiments. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0013]    The following description is of the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims. 
         [0014]      FIG. 1  is a schematic diagram of an exemplary embodiment of an illumination system, in accordance with some embodiments. The illumination system  100  comprises a driving device  110  and a load  120 . The driving device  110  generates output power AC OUT  to drive the load  120  according to input power AC IN . In this embodiment, the load  120  comprises illumination devices  121  and  122 , but the disclosure is not limited thereto. In some embodiments, the load  120  may comprise one or more illumination devices. The illumination devices  121  and  122  are continuously turned on according to the output power AC OUT . 
         [0015]    As shown in  FIG. 1 , the illumination devices  121  and  122  are connected to the driving device  110  in parallel and are capable of operating independently. For example, when the illumination device  121  fails or is removed from the illumination system  100 , when the driving device  110  continuously provides the output power AC OUT , the illumination device  122  can be turned on. Similarly, when the illumination device  122  fails or is removed from the illumination system  100 , the illumination device  121  can be turned on. 
         [0016]    Since the operation of each illumination device  121  and  122  is the same, the illumination device  121  is used herein as an example. As shown in  FIG. 1 , the illumination device  121  is a light tube  126  comprising filaments  127  and  128 . In one embodiment, before the driving device  100  provides the output power, the driving device  110  first preheats the filaments  127  and  128  to help the illumination device  121  to generate free electrons easily. Furthermore, when the light tube  126  is preheated, a light voltage across the light tube  126  can be reduced and the lift time of the light tube  126  can be increased. Therefore, before providing the output power AC OUT , the driving device  110  is capable of turning on the illumination device  121  quickly. In another embodiment, the driving device  110  does not preheat the illumination device  121  but directly provides the output power AC OUT . In this case, the illumination device  121  receives the output power AC OUT  to turn on. The invention does not limit the type of illumination device. In some embodiments, the illumination devices are bulbs. In one embodiment, the driving device  110  is capable of serving an electronic ballast having a filament-heating apparatus. 
         [0017]      FIG. 2  is a schematic diagram of an exemplary embodiment of a driving device, in accordance with some embodiments. The driving device  210  comprises converting modules  211  and  215 , capacitors  213  and  214 , a clamping module  212 , and a preheating module  216 . The converting module  211  converts the input power AC IN  into a direct current (DC) power P DC . In this embodiment, the converting module  211  comprises a pair of input terminals receiving the input power AC IN . The converting module  211  comprises a pair of output terminals coupled to the nodes N 1  and N 2 . In one embodiment, the input power AC IN  is an alternating current (AC) power and the peak-to-peak value of the AC power is approximately 347V. After the converting module  211  converts the AC power, the voltage level of the DC power P DC  is approximately 560V. In one embodiment, the converting module  211  is an AC-DC converter to convert AC power having a low frequency to DC power having a high frequency. In another embodiment, the converting module  211  has a power factor correction (PFC) function. 
         [0018]    The capacitors  213  and  214  are serially connected between the nodes N 1  and N 2 . As shown in  FIG. 2 , the capacitor  213  is coupled between the nodes N 1  and N 3 . The capacitor  214  is coupled between the nodes N 3  and N 2 . In this embodiment, the capacitance values of the capacitors  213  and  214  are micro-farad. In one embodiment, the capacitance values of the capacitors  213  and  214  are higher than 22 uF. In other embodiment, the capacitors  213  and  214  are integrated into the converting module  211 . In some embodiments, if the converting module  211  originally has two capacitors connected between the nodes N 1  and N 2  in series, the capacitors  213  and  214  can be omitted. 
         [0019]    The clamping module  212  is connected to the capacitor  213  or  214  in parallel to clamp the voltage across the capacitor  213  or  214 . In this embodiment, the clamping module  212  is connected to the capacitor  213  in parallel to clamp the voltage of the capacitor  213  and provides a charging path for the capacitor  214 . The invention does not limit the type of clamping module  212 . Any element or circuit can serve as the clamping module  212 , as long as the element or circuit is capable of clamping a voltage. In one embodiment, the clamping module  212  is a transient voltage suppressor (TVS), a surge absorber, or a metal oxide varistor (MOV). In some embodiments, if the converting module  211  originally has two capacitors connected between the nodes N 1  and N 2  in series, the clamping module  212  is connected to one of the capacitors in parallel. 
         [0020]    The converting module  215  converts the DC power P DC  to generate the output power AC OUT . As shown in  FIG. 2 , the pair of the input terminals of the converting module  215  is coupled to the nodes N 1  and N 2  to receive the DC power P DC . The pair of the output terminals of the converting module  215  provides the output power AC OUT  to light the load  220 . Since the internal structure of the load  220  is the same as that of the load  120 , the description of the load  220  is omitted. In this embodiment, the converting module  215  is a DC-AC converter to convert DC power with high voltage level to AC power with a high frequency. 
         [0021]    The preheating module  216  is connected to the capacitor  213  or  214  in parallel. In this embodiment, since the clamping module  212  is connected to the capacitor  213  in parallel, the preheating module  216  is connected to the capacitor  214  in parallel. The preheating module  216  transfers the energy stored in the capacitor  214  to provide preheating energy to preheat the filament of the load  220 . When the preheating module  216  captures the energy stored in the capacitor  214 , since the clamping module  212  limits the voltage of the capacitor  213 , the voltage across the capacitor  213  is not too high. Therefore, a designer does not need to utilize a high voltage capacitor to serve as the capacitor  213 . 
         [0022]    For example, assuming that the voltage level of the DC power P DC  is approximately 560V: Since the capacitor  213  is connected to the capacitor  214  in series, the capacitors  213  and  214  are charged, and the voltages of the capacitors  213  and  214  are approximately 280V. When the energy stored in the capacitor  214  is transferred to the preheating module  216 , since the voltage across the capacitor  214  is too low, the capacitor  213  is charged. However, the clamping module  212  limits the voltage across the capacitor  213 . In one embodiment, when the voltage across the capacitor  213  exceeds 300V, the clamping module  212  starts operating to stop charging the capacitor  213 . At this time, the clamping module  212  provides a charging path to charge the capacitor  214 . Therefore, the voltage of the capacitor  213  is not too high, and the voltage of the capacitor  214  can quickly be charged to 280V to supply the preheating module  216 . Since the voltages across the capacitors  213  and  214  are controlled, the voltages of the capacitors  213  and  214  are maintained. 
         [0023]    Additionally, when the voltage of the capacitor  213  does not reach the turn-on voltage (e.g. 300V) of the clamping module  212 , the clamping module  212  does not operate. Therefore, there is no power consumption. Furthermore, the voltages of the capacitors  213  and  214  are controlled by the clamping module  212  such that capacitors pressuring high voltage are not required to serve as the capacitors  213  and  214 . Therefore, the cost of elements is reduced. 
         [0024]      FIG. 3  is a schematic diagram of an exemplary embodiment of a driving device, in accordance with some embodiments.  FIG. 3  is similar to  FIG. 2  with the exception of the connections of the clamping module  312  and the preheating module  316 . Since the operations of the converting modules  311  and  315  are the same as those of the converting modules  211  and  215  shown in  FIG. 2 , the descriptions of the converting modules  311  and  315  are omitted. 
         [0025]    In this embodiment, the clamping module  312  is connected to the capacitor  314  in parallel to clamp the voltage of the capacitor  314 . When the voltage of the capacitor  314  reaches a clamping level, the clamping module  312  starts working to maintain the voltage of the capacitor  314  in the clamping level. In addition, the preheating module  316  is connected to the capacitor  313  in parallel to captures the energy stored in the capacitor  313  and transfer the energy to the filaments (not shown) of the load  320 . 
         [0026]    When the voltage of the capacitor  313  reaches a pre-determined level, the preheating module  316  captures the energy stored in the capacitor  313  and transforms the energy to a preheating energy to preheat the filaments of the load  320 . At this time, the voltage of the capacitor  313  is reduced. However, the clamping module  312  limits the voltage of the capacitor  314  to avoid the voltage of the capacitor  314  being too high. Therefore, the voltage of the capacitor  314  is maintained at a stable voltage to provide a stable heating energy. 
         [0027]    Furthermore, when the preheating module  316  does not transfer energy to the load  320 , the voltages of the capacitors  313  and  314  are not changed. Therefore, the clamping module  312  stops working, and there is no power consumption. In one embodiment, the clamping module  312  is a TVS, a surge absorber, or a MOV. 
         [0028]      FIG. 4  is a schematic diagram of an exemplary embodiment of a connection among a converting module, a preheating module and a load, in accordance with some embodiments. As shown in  FIG. 4 , the preheating module  416  comprises a DC-AC converter  431  and an isolation transformer  432 . The DC-AC converter  431  captures and converts input energy P I  to generate output energy P O . In this embodiment, the input energy P I  is provided by a capacitor. Taking  FIG. 2  as an example, the input energy P I  is the energy stored in the capacitor  214 . 
         [0029]    The isolation transformer  432  comprises a primary winding  433 , a magnetic core  434 , and secondary windings  435 ˜ 437 . The primary winding  433  is coupled to the DC-AC converter  431  to receive the output energy P O . The secondary winding  435  is coupled to two ends of the filament  425  to preheat the filament  425 . The secondary winding  436  is coupled to two ends of the filament  421  to preheat the filament  421 . The secondary winding  437  is coupled to two ends of the filaments  424  and  426  to preheat the filaments  424  and  426 . 
         [0030]    When the primary winding  433  receives the output energy P O , the secondary windings  435 ˜ 437  generate preheating energy to preheat the filaments  423 - 426 . When the converting module  415  provides the output power AC OUT , the light tubes  421  and  422  are lighted quickly. Since the converting module  415  is the same as the converting module  215  or  315 , the description of the converting module  415  is omitted. 
         [0031]    In one embodiment, the preheating module  416  operates temporarily, such as for 0.5 sec. After preheating the filaments  423 ˜ 426 , the preheating module  416  stops operating. At this time, when the converting module  415  provides the output power AC OUT , the light tubes  421  and  422  are lighted quickly. 
         [0032]      FIG. 5  is a schematic diagram of another exemplary embodiment of an illumination system, in accordance with some embodiments. The illumination system  500  comprises a driving device  510  and a load  520 . The driving device  510  generates output power AC OUT  to drive the load  520  according to input power AC IN . In this embodiment, the load  520  comprises illumination devices  521  and  522 . The illumination devices  521  and  522  are turned on according to the output power AC OUT . 
         [0033]      FIG. 6  is a schematic diagram of another exemplary embodiment of a driving device, in accordance with some embodiments. The driving device  510  comprises converting modules  511  and  515 , capacitors  513  and  514 , and clamping modules  512  and  516 . Since the operations of the converting modules  511  and  515  are the same as the operations of the converting modules  211  and  215 , the descriptions of the converting modules  511  and  515  are omitted. In this embodiment, the clamping module  512  is connected to the capacitor  513  in parallel, and the clamping module  516  is connected to the capacitor  514  in parallel. 
         [0034]    Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. 
         [0035]    While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.