Patent Publication Number: US-8525426-B2

Title: Lighting apparatus and controlling method thereof

Description:
FIELD OF THE INVENTION 
     The instant disclosure relates to a lighting apparatus and controlling method thereof; in particular, to a LED lighting apparatus and controlling method thereof. 
     DESCRIPTION OF RELATED ART 
     To operate a light emitting diode (LED), an AC power is typically used to drive the LED. As shown in  FIG. 1 , such powering option directs the AC power into a rectifying circuit BR. After rectification, the current passes through a current limiting resistor R 1  to drive a LED array LA. However, if the AC power is unstable, such driving method may cause the following problems. 
     First, the output power would become unstable. In other words, based on the peak voltage of the AC power, the current passes through the LED array LA would fluctuate. Consequently, the output power of the LED array LA would be unstable and affect the luminous intensity. The instability makes the LED array LA to be more susceptible to damage and less bright. 
     Secondly, the LEDs would have low light output. For a LED array LA, the value of overall cut-in voltage is usually set near the peak voltage of the AC power. The AC power is represented by a sine wave, where the peak voltage only occurs for a short time in every cycle. Therefore, only a short time is allowed for current flow across the LEDs. Under such condition, the value of peak current must be raised, in order to maintain a fixed value for the average current flowing across the LED array LA. In general, the relationship between the light intensity of the LED and current flow is not linear. For example, if the LED intensity is 1 mcd for a current of 1 amp, when the current is up to 2 amps, the LED intensity is 1.6 mcd instead of 2 mcd. As a result, for the LED array LA, if the value of cut-in voltage is set near the peak voltage of the AC power, when the AC power is unstable, the light output would fluctuate and cause the light output efficiency of the LED array LA to be reduced. The overall system efficiency would be affected accordingly, where the overall system efficiency is defined by multiplying the LED driving efficiency to the LED light output efficiency. 
     SUMMARY OF THE INVENTION 
     The instant disclosure provides a lighting apparatus and controlling method thereof. Through an input power derived from the rectification of the AC power, the lighting apparatus changes the connection relationship between the rectifier and at least two lighting modules thereof. The purpose is to enhance the light output efficiency and extend the service life. 
     According to one embodiment, the lighting apparatus of the instant disclosure receives an alternating current (AC) and comprises a first lighting module, a second lighting module, a rectifier, and a controller. The rectifier converts the AC into an input power. The controller is coupled to the rectifier, the first lighting module, and the second lighting module. The controller receives the input power. When the input power is less than a reference value, the controller controls the first lighting module, the second lighting module, and the rectifier to form a first connection state. Conversely, when the input power is greater than the reference value, the controller controls the first lighting module, the second lighting module, and the rectifier to form a second connection state. 
     According to another embodiment, the controlling method of the lighting apparatus of the instant disclosure is suitable for a controller of controlling a first lighting module and a second lighting module. The controlling method includes the steps of: obtaining an input power of rectified AC; controlling the first lighting module, the second lighting module, and the rectifier to form a first connection state, when the input power is less than a reference value; and controlling the first lighting module, the second lighting module, and the rectifier to form a second connection state, when the input power is greater than the reference value. 
     Still according to another embodiment, the controlling method of the lighting apparatus of the instant disclosure is suitable for a controller of controlling a plurality of lighting modules. The controlling method comprises the steps of: obtaining an input power of rectified AC; controlling the plurality of lighting modules and the rectifier to form a first connection state, when the input power is less than a first reference value; controlling the plurality of lighting modules and the rectifier to form a second connection state, when the input power is greater than the first reference value and less than a second reference value; and controlling the plurality of lighting modules and the rectifier to form a third connection state, when the input power is greater than the second reference value. 
     Based on the above, the embodiments of the instant disclosure use the input power of rectified AC to change the connection relationship between two or more lighting modules and the rectifier. Along with obtaining a fixed average current, the value of peak current flowing across the lighting module can be reduced, thereby increasing the light output efficiency and service life. 
     In order to further appreciate the characteristics and technical contents of the instant disclosure, references are hereunder made to the detailed descriptions and appended drawings in connection with the instant disclosure. However, the appended drawings are merely shown for exemplary purposes, rather than being used to restrict the scope of the instant disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a driving circuitry of a typical light emitting diode (LED). 
         FIG. 2  shows a function block diagram for an embodiment of the instant disclosure. 
         FIG. 3  shows a circuit diagram for the first embodiment of the instant disclosure. 
         FIG. 4  shows the waveforms of the circuitry shown in  FIG. 3 . 
         FIG. 5  shows a circuit diagram for the second embodiment of the instant disclosure. 
         FIG. 6  shows a circuit diagram for the third embodiment of the instant disclosure. 
         FIG. 7  shows the waveforms of the circuitry shown in  FIG. 6 . 
         FIG. 8  shows the circuit diagram for the fourth embodiment of the instant disclosure. 
         FIG. 9  shows the circuit diagram for the fifth embodiment of the instant disclosure. 
         FIG. 10  shows the waveforms for the circuitry shown in  FIG. 9 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     For the lighting apparatus of the present embodiment of the instant disclosure, the driving technique thereof utilizes rectified AC as the input power to drive two or more lighting modules. The lighting module can be a light emitting diode (LED) or a LED array. The LED array includes a plurality of LEDs, which can be wired in series or in parallel, or a combination thereof. However, the LED or the LED array is not the only choice. Any lighting module that can be driven directly by the input power, or rectified AC, is included in the scope of the instant disclosure. 
     Please refer to  FIG. 2 , which shows a function block diagram for the preferred embodiment of the instant disclosure. The lighting apparatus  1  includes a controller  10 , a rectifier  11 , a first lighting module  12 , and a second lighting module  14 . The controller  10  is coupled to the rectifier  11 , the first lighting module  12 , and the second lighting module  14 . The rectifier  11  converts an AC into an input power Vbr. The voltage waveform of the input power Vbr is of the rectified AC, where the usual waveform of an AC is a sine wave. Therefore, the voltage magnitude of the input power Vbr changes accordingly with the AC. 
     Please refer back to  FIG. 2 . The controller  10  receives the input power Vbr and detects the voltage magnitude thereof. Meanwhile, the controller  10  is encrypted with a reference value. When the voltage of the input power Vbr is less than the reference value, the controller  10  controls the first lighting module  12 , the second lighting module  14 , and the rectifier  11  to form a first connection state. When the voltage of the input power Vbr is greater than the reference value, the controller  10  controls the first lighting module  12 , the second lighting module  14 , and the rectifier  11  to form a second connection state. 
     So, based on the input power Vbr of rectified AC, the lighting apparatus  1  can change the connection state between the first lighting module  12 , the second lighting module  14 , and the rectifier  11 . By obtaining a fixed average current, the value of the peak current of every voltage cycle across the first lighting module and the second lighting module can be reduced. Therefore, a high light output efficiency and long service life can be achieved. 
     Please refer to  FIG. 3 .  FIG. 3  shows a circuit diagram for a first embodiment of the instant disclosure, based on the previously mentioned function block. The rectifier  11  is a full-wave rectifier used to convert AC into input power Vbr. The rectifier  11  may be made of a rectifier chip or four diodes BR 1 ˜BR 4 . Since the technology is obvious to someone skilled in the art, no further elaborations are given here. 
     The controller  10  includes a switch  102  and a controlling unit  104 . The switch  102  is coupled to the first lighting module  12  and the second lighting module  14 . The controlling unit  104  is coupled to the rectifier  11  and the switch  102 . By determining whether the voltage of the input power Vbr is greater than the reference value or not, the controlling unit  104  controls the operation of the switch  102  accordingly. The operation of the switch  102  can change the connection relationship between the first lighting module  12 , the second lighting module  14 , and the rectifier  11 . Based on whether the voltage of the input power Vbr is greater than the reference value or not, the connection relationship between the three components is either in the first or second connection state. 
     Please refer back to  FIG. 3 . The switch  102  includes a diode D 1 , a first transistor Q 1 , and a second transistor Q 2 . The associated connection relationship and operating schemes are explained below. The anode end of the diode D 1  is connected to the output end T 12  of the first lighting module  12 . The cathode end of the diode D 1  is connected to the input end T 21  of the second lighting module  14 . The input/output end C 1  of the first transistor Q 1  is connected to the cathode end of the diode D 1  via a current limiting resistor R 3 . The other input/output end E 1  of the first transistor Q 1  is connected to the input end T 11  of the first lighting module  12 . The controlling end B 1  of the first transistor Q 1  is connected to the controlling unit  104 . Meanwhile, the input/output end C 2  of the second transistor Q 2  is connected to the output end T 22  of the second lighting module  14  via a current limiting resistor R 2 . The output end T 22  of the second lighting module  14  is connected to the ground Gnd and the rectifier  11  via a current limiting resistor R 1 . The input/output end E 2  of the second transistor Q 2  is connected to the anode end of the diode D 1 , and the controlling end B 2  of the transistor Q 2  is connected to the controlling unit  104 . 
     The current limiting circuitry of the present embodiment includes the current limiting resistors R 1 , R 2 , and R 3 . However, the illustrated current limiting circuitry is not the only choice. Any circuitry that can control the current flow across the lighting module based on the input power Vbr is included in the scope of the instant disclosure. 
     Please refer back to  FIG. 3 . The controlling unit  104  includes a bleeder circuit  1042  and a driver circuit  1044 . The bleeder circuit  1042  is connected to the rectifier  11 . Based on the input power Vbr, the bleeder circuit  1042  creates an input voltage reference value VR, which is proportional to the input power Vbr. For the instant embodiment, the bleeder circuit  1042  includes resistors R 12  and R 13 . However, the illustrated scheme is not the only choice. Any bleeder circuit that can create an input voltage reference value VR based on the input power Vbr is included in the scope of the instant disclosure. 
     The driver circuit  1044  is coupled to the bleeder circuit  1042  for receiving the input voltage reference value VR. The driver circuit  1044  is encrypted with a set value Vth. When the input voltage reference value VR is less than the set value Vth, the driver circuit  1044  turns on the first transistor Q 1  and the second transistor Q 2 . Thus, the first lighting module  12 , the second lighting module  14 , and the rectifier  11  form a first connection state. On the other hand, when the input voltage reference value VR is greater than the set value Vth, the driver circuit  1044  turns off the first transistor Q 1  and the second transistor Q 2 . Thus, the first lighting module  12 , the second lighting module  14 , and the rectifier  11  form a second connection state. 
     For the instant embodiment, the driver circuit  1044  comprises two transistors Q 3  and Q 4 . However, the illustrated scheme is not the only choice. Any circuitry that can drive the first transistor Q 1  and the second transistor Q 2  based on the comparison of the input voltage reference value and the set value is under the scope of the instant disclosure. 
     Please refer to  FIGS. 3 and 4 .  FIG. 4  shows the waveforms of the circuit diagram in  FIG. 3 . The controlling unit  104  receives the input power Vbr from the rectifier  11 , and creates the input voltage reference value VR on the resistor R 13  of the bleeder circuit  1042 . For the input power Vbr during the time lapse T 1 , the established input voltage reference value VR on the resistor R 13  is less than the set value Vth of the transistor Q 4  (meaning the input power Vbr is less than the reference value Vref). For the time interval T 1 , the resistance voltage VR 12  established on the bleeder circuit  1042  would turn on the transistor Q 3 , thus having the first transistor Q 1  and the second transistor Q 2  in a turned-on state. In turn, the first lighting module  12  and the second lighting module  14  connected to the rectifier  11  in parallel form the first connection state. Meanwhile, the current I 1  flowing across the first lighting module  12  and the second lighting module  14  is shown in  FIG. 4 . 
     Yet, for the time lapse T 2 , as the voltage of the input power Vbr increases, the input voltage reference value VR established on the resistor R 13  becomes greater than the set value Vth of the transistor Q 4  (meaning the input voltage Vbr is greater than the reference value Vref). For the time interval T 2 , the transistor Q 4  is turned on, and the transistor Q 3  is turned off. By being off, the transistor Q 3  thus having the first transistor Q 1  and the second transistor Q 2  in a turned-off state. In turn, the first lighting module  12  and the second lighting module  14  connected to the rectifier  11  in parallel form the second connection state. Meanwhile, the current I 2  flowing through the first lighting module  12  and the second lighting module  14  is shown in  FIG. 4 . 
     In other words, for the lower input power Vbr, the controlling unit  104  controls the switch  102 , in connecting the first lighting module  12  and the second lighting module  14  in parallel. The lower input power Vbr is thus supplied to the first lighting module  12  and the second lighting module  14  in parallel. Since the first lighting module  12  and the second lighting module  14  in parallel have a lower cut-in voltage, therefore, a lower input voltage Vbr is sufficient to create the current flow I 1  through the first lighting module  12  and the second lighting module  14 . In addition, under the higher input power Vbr, the controlling unit  104  controls the switch  102 , in connecting the first lighting module  12  and the second lighting module  14  in series. The higher input power Vbr is thus supplied to the first lighting module  12  and the second lighting module  14  in series. Since the first lighting module  12  and the second lighting module  14  in series have a higher cut-in voltage, therefore, a higher input power Vbr can create a current flow  12  through the first lighting module  12  and the second lighting module  14 . 
     So, by supplying the lower input power Vbr to the first lighting module  12  and the second lighting module  14  in parallel, and supplying the higher input power Vbr to the first lighting module  12  and the second lighting module  14  in series, with obtaining a fixed average current, the peak current value of the voltage through the first lighting module  12  and the second lighting module  14  for every cycle can be reduced. Thus, the goals of high light output efficiency and long service life are achieved. 
     Please refer back to  FIGS. 3 and 4 . The input power Vbr (or the input voltage reference value VR) comes from rectified AC having a sine wave. The voltage waveform is symmetrical at 90 degrees. Therefore, for the controlling unit  104  during the time intervals T 3  and T 4 , the controlling operation of the transistors Q 3  and Q 4  corresponds to T 2  and T 1  respectively as shown in  FIG. 4 . 
     From the above, based on the voltage magnitude of the input power Vbr for every cycle, the controlling unit  104  controls the first lighting module  12 , the second lighting module  14 , and the rectifier  11  to be in the first connection state, the second connection state, and back to the first connection state. Therefore, driven by a fixed average current, the controlling mode of the controlling unit  104  would reduce the peak current value (such as current I 2 ) for the voltage through the first lighting module  12  and the second lighting module  14  of every cycle. Hence, the light output efficiency and service life are increased for the lighting apparatus  1 . 
     Please refer to  FIG. 5 , which shows a circuit diagram for a second embodiment of the instant disclosure. The main difference between the lighting apparatus  2  of the instant embodiment and the lighting apparatus  1  in  FIG. 3  is the controller  20 . The controller  20  of the lighting apparatus  2  includes a switch  202  and a controlling unit  204 . The switch  202  is a transistor Q 3 . The input/output end C 3  of the transistor Q 3  is connected to the output end T 12  of the first lighting module  12  and the input end T 21  of the second lighting module  14  via the current-limiting resistor R 2 . The input/output end E 3  of the transistor Q 3  is connected to the ground Gnd, and the output end T 22  of the second lighting module  14  is connected to the ground Gnd via the current-limiting resistor R 1 . The controlling end B 3  of the transistor Q 3  is connected to the controlling unit  204 . 
     Please refer back to  FIG. 5 . The controlling unit  204  includes a bleeder circuit  2042  and a driver circuit  2044 . The bleeder circuit  2042  is the same as the bleeder circuit  1042  in  FIG. 3 , therefore is not described here again in detail. Meanwhile, the driver circuit  2044  comprises a transistor Q 4 . Based on the comparison between the input voltage reference value VR and the set value Vth, the driver circuit  2044  drives the transistor Q 3 . In turn, the first lighting module  12 , the second lighting module  14 , and the rectifier  11  form the first connection state or the second connection state accordingly. 
     Hence, the controlling unit  204  receives the input power Vbr from the rectifier  11  and creates the input voltage reference value VR on the resistor R 13  of the bleeder circuit  2042 . When the input voltage reference value VR is less than the set value Vth of the transistor Q 4 , the resistance voltage VR 12  established on the bleeder circuit  2042  would first turn on the transistor Q 3 . Thereby, the first lighting module  12  is connected electrically to the rectifier  11  singly, and the second lighting module  14  is cut off from the rectifier  11  in forming a first connection state. 
     Meanwhile, as the input voltage Vbr increases, the input voltage reference value VR increases accordingly. When the input voltage reference value VR is greater than the set value Vth of the transistor Q 4 , the transistor Q 4  is turned on in turning the transistor Q 3  off. Therefore, the first lighting module  12  and the second lighting module  14  are electrically connected to the rectifier  11  in series in forming the second connection state. 
     In other words, for the lower input power Vbr, the controlling unit  204  controls the switch  202 , to have the first lighting module  12  connecting electrically to the rectifier  11  singly. The lower input power Vbr is thus supplied to power the first lighting module  12 . By itself, the first lighting module  12  has a lower cut-in voltage. Therefore, a lower input power Vbr is sufficient to operate the first lighting module  12  singly. On the other hand, for the higher input power Vbr, the controlling unit  204  controls the switch  202 , to connect the first lighting module  12  with the second lighting module  14  in series, and allowing the higher input power Vbr to power the first lighting module  12  and the second lighting module  14 . Since the first lighting module  12  and the second lighting module  14  in series have a higher cut-in voltage, therefore, the higher input power Vbr is able to power the first lighting module  12  and the second lighting module  14 . 
     So, by using the lower input power Vbr to power the first lighting module  12 , and using the higher input power Vbr to power the first lighting module  12  and the second lighting module  14  in series, the peak current value for every voltage cycle through the first lighting module  12  and the second lighting module  14  can be reduced. Hence, the higher light output efficiency and the longer service life are achieved. 
     From the above, based on the voltage magnitude of the input power Vbr for every cycle, the controlling unit  204  controls the first lighting module  12 , the second lighting module  14 , and the rectifier  11  to be in the first connection state, the second connection state, and back to the first connection state. Therefore, driven by a fixed average current, the controlling mode of the controlling unit  204  would reduce the peak current value for the voltage through the first lighting module  12  and the second lighting module  14  of every cycle. Hence, the light output efficiency and the service life are increased for the lighting apparatus  2 . 
     Please refer to  FIG. 6  along with  FIG. 3 .  FIG. 6  shows a circuit diagram for a third embodiment of the instant disclosure. The main difference between the lighting apparatus  3  of the instant embodiment and the lighting apparatus  1  in  FIG. 3  is that the lighting apparatus  3  further includes a power compensation module  16 . The power compensation module  16  is coupled to the rectifier  11 , the controller  10 , the first lighting module  12 , and the second lighting module  14 . Based on the voltage magnitude of the input power Vbr, the power compensation module  16  adjusts the main current ILED flowing across the first lighting module  12  and the second lighting module  14 . In other words, based on the voltage magnitude of the input power Vbr, the power compensation module  16  compensates the main current ILED flowing across the first lighting module  12  and the second lighting module  14 . The purpose is to ensure the input power is within a specified range for a given range of AC. 
     In the above discussion, the lighting apparatus  3  utilizes the power compensation module  16  for current compensation, which can suppress the peak current flowing across the first lighting module  12  and the second lighting module  14 . As shown in  FIG. 7 , the peak value of the current I 1  flowing across the first lighting module  12  and the second lighting module  14  for the time interval T 1  is flatter in comparing to  FIG. 4 . On the other hand, for the time interval T 2 , the peak value of the current I 2  flowing across the first lighting module  12  and the second lighting module  14  is also flatter. 
     Notably, the power compensation module  16  can couple to the rectifier  11 , the first lighting module  12 , and the second lighting module  14  in forming a lighting apparatus (not shown) without the controller  10 . The power compensation module  16  provides current compensation to the lighting apparatus, for ensuring the input power of the lighting apparatus is within a specified range. 
     The power compensation module  16  includes a voltage-controlled current source  162  and a constant current source  164 . The voltage-controlled current source  162  is coupled to the rectifier  11 , and based on the voltage magnitude of the input power Vbr, outputs a compensating current Ibr accordingly. For example, the greater the voltage for the input power Vbr, the output compensating current Ibr is greater also. The less the voltage of the input power Vbr, the output compensating current Ibr is less accordingly. The aforementioned voltage-controlled current source  162  comprises resistors R 1  and R 2 , and a zener diode ZD 1 . The voltage-controlled current source  162  obtains the voltage of the input power Vbr through the front end input, and based on the voltage magnitude of the input power Vbr, outputs the corresponding compensating current Ibr to compensate the main current ILED. 
     On the other hand, the constant current source  164  is coupled o the voltage-controlled current source  162 , the controller  10 , the first lighting module  12 , and the second lighting module  14 . The constant current source  164  receives the compensating current Ibr from the voltage-controlled current source  162 , and based on the magnitude of the compensating current Ibr, adjusts the main current ILED flowing across the first lighting module  12  and the second lighting module  14 . For example, the greater the compensating current Ibr, the lesser the main current ILED flowing across the first lighting module  12  and the second lighting module  14 . Conversely, the lesser the compensating current Ibr, the greater the main current ILED flowing across the first lighting module  12  and the second lighting module  14 . 
     Based on the above, the power compensation module  16  attains the voltage of the input power Vbr, and based on the voltage magnitude of the input power Vbr, compensates accordingly the main current ILED flowing across the first lighting module  12  and the second lighting module  14 . Therefore, the main current ILED is kept within a prescribed range. 
     So, the lighting apparatus  3  of the instant disclosure utilizes the power compensation module  16  to provide current compensation to the main current ILED. Thus, the main current ILED is kept from being affected negatively by the instability of the input power Vbr, while keeping the input power within a prescribed range. Thus, a solution is provided in resolving the issue of LED damage and light failure due to the instability of the AC. 
     Please refer back to  FIG. 6 . The constant current source  164  includes transistors Q 5  and Q 6  and resistors R 4 , R 5 , and R 6 . The resistor R 4  is coupled to the input power Vbr, for providing bias current to the transistor Q 5  and driving current to the transistor Q 6 . The controlling end B 6  of the transistor Q 6  is controlled by the transistor Q 5 . The current ID flowing across the resistor R 6  is the main current ILED, and the current ID establishes voltage VR 6  on the resistor R 6 , for allowing the transistor Q 5  to operate in the active region. Thereby, the transistor Q 5  connected to the controlling end B 6  of the transistor Q 6  is able to be used to adjust the main current ILED flowing across the transistor Q 6 . Thus, the main current ILED is kept at a fixed current value. 
     On the other hand, the compensating current Ibr outputted by the voltage-controlled current source  162  flows to the resistor R 6  via the resistor R 5  of the constant current source  164 . When the resistance of the resistor R 5  is much greater than the resistance of the resistor R 6 , the voltage VR 6  would form an offset voltage of Ibr×R 5 . Based on Thevenin&#39;s theorem, ID×R 6 =VR 6 −Ibr×R 5 . Therefore, the compensating current Ibr outputted by the voltage-controlled current source  162  provides current compensation to the main current ILED. Based on the voltage magnitude of the input power Vbr, the main current ILED can change accordingly to maintain the input power within a prescribed range. In turn, the issue of LED damage and light failure of the first lighting module  12  and the second lighting module  14  due to the instability of the AC is resolved. 
     Please refer back to  FIG. 6 . The voltage-controlled current source  162  can also couple to the output end T 12  of the first lighting module  12  and the output end T 22  of the second lighting module  14 . Based on the voltage difference ΔV between the input power Vbr and first lighting module  12  plus the second lighting module  14 , the voltage-controlled current source  162  would output the compensating current Ibr accordingly. The aforementioned voltage-controlled current source  162  includes a resistor R 3  and a zener diode ZD 2 . The voltage-controlled current source  162  attains the voltage difference ΔV through the back end thereof, and outputs the corresponding compensating current Ibr based on the voltage difference ΔV for current compensation of the main current ILED. 
     For example, when the first lighting module  12  and the second lighting module  14  are connected in parallel, the voltage difference ΔV is approximately equal to the input power Vbr minus the forward biased voltage V 1  of the first lighting module  12  or minus the forward biases voltage V 2  of the second lighting module  14 . Namely, ΔV=Vbr−V 1  or ΔV=Vbr−V 2 . When the first lighting module  12  and the second lighting module  14  are connected in series, the voltage difference ΔV is approximately equal to the input power Vbr minus the forward biased voltage of the first lighting module  12  and the second lighting module  14 . Namely, ΔV=Vbr−(V 1 +V 2 ). 
     Please refer back to  FIG. 6 . The aforementioned voltage-controlled current source  162  can also include the resistors R 1 ˜R 3  and the zener diodes ZD 1 ˜ZD 2 . Based on the front end and back end attaining technique, the voltage-controlled current source  162  outputs the corresponding compensating current Ibr for current compensation of the main current ILED. 
     Please refer to  FIG. 8  in conjunction with  FIG. 5 .  FIG. 8  shows the circuit diagram for a fourth embodiment of the instant disclosure. The main difference between the lighting apparatus  4  of the instant embodiment and the lighting apparatus  2  in  FIG. 5  is that the lighting apparatus  4  further includes a power compensation module  46 . The power compensation module  46  is coupled to the rectifier  11 , the controller  20 , the first lighting module  12 , and the second lighting module  14 . Based on the voltage magnitude of the input power Vbr, the power compensation module  46  adjusts the main current ILED flowing across the first lighting module  12  and the second lighting module  14  accordingly. The description of the power compensation module  46  is the same as the power compensation module  16  shown in  FIG. 6 , therefore no further elaboration is given here. 
     Please refer to  FIG. 9 , which shows the circuit diagram for a fifth embodiment of the instant disclosure. The lighting apparatus  5  includes a controller  50  and a plurality of lighting modules  52 . The plurality of lighting modules  52  comprises four lighting modules  52 A,  52 B,  52 C, and  52 D, but is not limited thereto. The controller  50  is coupled to the rectifier  51  and the plurality of lighting modules  52 , where the controller  50  receives the input power Vbr from the rectifier  51 . 
     Using the input power Vbr of the rectified AC, a controlling unit  501  of the controller  50  controls the switches S_H 1 ˜S_H 3 , S_L 1 ˜S_L 3 , and S_M 1 ˜S_M 3  accordingly. The goal is to change the connection relationship between the plurality of lighting modules  52  and the rectifier  51 . In turn, for every voltage cycle, the value of the peak current flowing across the lighting module  52  can be reduced, to achieve a high light output efficiency and a long service life for the lighting apparatus  5 . 
     Please refer to  FIGS. 9 and 10 .  FIG. 10  shows the waveforms for the circuit diagram in  FIG. 9 . When the input power Vbr is less than a first reference value Vref 1  for the time interval T 1 , the switches S_H 1 ˜S_H 3 , S_L 1 ˜S_L 3  are turned on while S_M 1 ˜S_M 3  are turned off inside the controller  50 . The configuration allows the lighting modules  52 A,  52 B,  52 C, and  52 D to be electrically connected with the rectifier  51  in parallel in forming the first connection state. Meanwhile, the current I 11  flowing across the lighting modules  52 A,  52 B,  52 C, and  52 D is shown in  FIG. 10 . 
     Next, when the input power Vbr is greater than the first reference value Vref 1  but less than a second reference value Vref 2  for the time interval T 2 , the switches S_H 1 , S_H 3 , S_L 1 , S_L 3 , and S_M 2  are turned off, while the switches S_H 2 , S_L 2 , S_M 1 , and S_M 3  are turned on. The configuration allows the lighting modules  52 A and  52 B to be electrically connected with the rectifier  51  in series, and the lighting modules  52 C and  52 D to be electrically connected with the rectifier  51  in series in forming the second connection state. 
     Meanwhile, the current I 12  flowing across the lighting modules  52 A,  52 B,  52 C, and  52 D is shown in  FIG. 10 . 
     Furthermore, when the input power Vbr is greater than the second reference value Vref 2  for the time interval T 3 , the switches S_H 1 , S_H 3 , S_L 1 , S_L 3 , S_H 2 , S_L 2  are turned off, and the switches S_M 1 ˜S_M 3  are turned on within the controller  50 . The configuration allows the lighting modules  52 A,  52 B,  52 C, and  52 D to connect electrically with the recitifier  51  in series in forming the third connection state. Meanwhile, the current I 13  flowing across the lighting modules  52 A,  52 B,  52 C, and  52 D is shown in  FIG. 10 . 
     Please refer back to  FIGS. 9 and 10 . The input power Vbr has a sine wave of rectified AC. The voltage waveform is symmetrical at 90 degrees. Therefore, for the time intervals T 4 , T 5 , and T 6 , the controller  50  operations about the switches S_H 1 ˜S_H 3 , S_L 1 ˜S_L 3 , and S_M 1 ˜S_M 3  correspond to the switch operations during the time intervals T 3 , T 2 , and T 1  respectively, as shown in  FIG. 10 . 
     From the above, based on the voltage magnitude of the input power Vbr, the controller  50  would configure the connection relationship between the lighting modules  52 A,  52 B,  52 C, and  52 D with the rectifier  51  in a cycle, namely the first connection state, the second connection state, the third connection state, the second connection state, and the first connection state. Therefore, under the driving mode of fixed mean current, the controlling mode of the controller  50  can reduce the value of peak current for every voltage cycle across the lighting modules  52 A,  52 B,  52 C, and  52 D. In turn, the light output efficiency is increased along with longer service life for the lighting apparatus  5 . 
     Please refer to  FIG. 9 . The lighting apparatus further includes a power compensation module  56 . The power compensation module  56  is coupled to the rectifier  51 , the controller  50 , and the plurality of lighting modules  52 . Based on the voltage magnitude of the input power Vbr, the power compensation module  56  adjusts the main current ILED flowing across the plurality of lighting modules accordingly. Since the description of the power compensation module  56  is the same as the power compensation module  16  in  FIG. 6 , no further details are elaborated here. 
     For the fifth embodiment of the instant diclosure, as disclosed in  FIG. 10  of the switch control sequence, the controller  50  symmetrically controls the connection relationship between the lighting modules  52 A,  52 B,  52 C, and  52 D with the rectifier  51 . The illustrated control sequence is not the only choice of the control mode. Any circuitry that can control the connection relationship between the lighting modules based on the input power Vbr is covered under the claims of the instant disclosure. 
     The descriptions illustrated supra set forth simply the preferred embodiments of the instant disclosure; however, the characteristics of the instant disclosure are by no means restricted thereto. All changes, alternations, or modifications conveniently considered by those skilled in the art are deemed to be encompassed within the scope of the instant disclosure delineated by the following claims.