Abstract:
A power converter that receives a plurality of direct current (DC) powers, which are received in different modes and have a common ground and substantially the same potential, and operates a plurality of loads, wherein the power converter operates the respective loads according to input states of the plurality of DC powers and supplies the plurality of loads with power via at least a common switch element or a common coil.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a 35 U.S. §371 national stage filing of International Application No. PCT/IB2010/053269, filed Jul. 19, 2010, the entire contents of which are incorporated by reference herein, which claims priority to Japanese Patent Application No. 2009-173693, filed Jul. 24, 2009, the entire contents of which are incorporated by reference herein. 
     TECHNICAL FIELD 
     The present invention relates to a power converter that receives a plurality of substantially same potentials and supplies power to a plurality of loads, and a vehicle lighting device, a vehicle headlight and a vehicle using the power converter. 
     BACKGROUND 
     Existing power converters receive a single input and output a single output. However, as power sources or loads become more diverse, the need to generate a plurality of outputs in response to a plurality of inputs (which are input at various times) is becoming desirable. Particularly, in the field of a power converters mounted in vehicles, various control units have been integrated, and multi-input multi-output devices are becoming more desirable. 
       FIG. 18  illustrates a power converter that controls loads of two systems as an example of a vehicle lighting device having a plurality of light sources. The power converter receives a power  1  directly connected to a vehicle battery BT. A controller area network (CAN) communication  2  which is a vehicle communication controller, controls a light emitting diode (LED)  3  (reading light) and an LED  4  (foot light) of two systems. The respective inputs are received by an input connection unit  10 , and an output is output to the LEDs  3  and  4  of two systems via an output connection unit  11 . The power converter is configured to include first and second power converting units  8  and  9  for converting a voltage of the battery directly-connected power  1  into a certain current required by the LEDs  3  and  4 , a control unit  7  for controlling the first and second power converting units  8  and  9 , a control power supply unit  5  that receives the battery directly-connected power  1  and outputs the power  1  to the control unit  7 , and a transceiver  6  that receives the CAN communication  2  notifying lighting timing of the LEDs  3  and  4 . The control unit  7  controls the LEDs  3  and  4  by receiving detection signals corresponding to output current values from the first and second power converting units  8  and  9  and outputting driving signals to the first and second power converting units  8  and  9 . 
       FIGS. 19 and 20  illustrate the first power converting unit  8  and the second power converting unit  9 , respectively.  FIG. 19  illustrates a configuration of a flyback circuit which is an example of the power converting unit. A direct current (DC) power (a voltage between +B and GND) is received by a condenser C 1 , and a series circuit of a primary side winding TP 1  of a transformer T 1  and a switch element SW 1  is connected in parallel to the condenser C 1 . A driving signal of the switch element SW 1  is input to the power converting unit. A series circuit of a secondary side winding TS 1  of the transformer T 1  and a diode D 1  are connected in parallel to a condenser C 2 . An output unit is installed to connect a series circuit of a load and a resistor R 1  in parallel to the condenser C 2 . An output current is detected by the resistor R 1  and output as the detection signal. 
     A description will be made below in connection with a circuit operation. A current flows from the condenser C 1  to the primary side winding TP 1  of the transformer T 1  and the switch element SW 1  at ON timing of the switch element SW 1 . A direction of the diode D 1  at the secondary side is set to a direction in which a secondary side current does not flow when the switch element SW 1  is turned on, so that energy is accumulated in the transformer T 1 . The energy accumulated in the transformer T 1  moves from the secondary side winding TS 1  of the transformer T 1  to the condenser C 2  via the diode D 1  at OFF timing of the switch element SW 1 . Power is supplied from the condenser C 2  to the load via the resistor R 1 . An output current is detected by the resistor R 1 , and the control unit  7  adjusts an ON/OFF time of the driving signal of the switch element SW 1 . Thus, the output current can be constantly controlled. 
       FIG. 20  illustrates a configuration of a boosting circuit using an auto transformer which is an example of the power converting unit. A DC power (a voltage between +B and GND) is received by a condenser C 3 , and a series circuit of a primary side winding TP 2  of a coil T 2  and a switch element SW 2  is connected in parallel to the condenser C 3 . A driving signal of the switch element SW 2  is input to the power converting unit. A secondary side winding TS 2  of the transformer T 2 , a diode D 2 , and a condenser C 4  are connected in series to one another and in parallel to the switch element SW 2 . The primary side winding TP 2  and the secondary side winding TS 2  of the coil T 2  are wounded to have an additive polarity, and the diode D 2  is installed in a direction in which a current flows from the power to the output side. An output unit is installed to connect a series circuit of a load and a resistor R 2  in parallel to the condenser C 4 . An output current is detected by the resistor R 2 , and the detected output signal is output as a detection signal. 
     A description will be made below in connection with a circuit operation. A current flows from the condenser C 3  to the primary side winding TP 2  of the coil T 2  and the switch element SW 2  at ON timing of the switch element SW 2 , and energy is accumulated in the coil T 2 . The energy accumulated in the coil T 2  moves to the condenser C 4  via the condenser C 3 , the coil T 2 , and the diode D 2  at OFF timing of the switch element SW 2 . Power is supplied from the condenser C 4  to the load via the resistor R 2 . An output current is detected by the resistor R 2 , and the control unit  7  adjusts an ON/OFF time of the driving signal of the switch element SW 2 . Thus, the output current can be constantly controlled. 
       FIG. 21  illustrates a power converter having a different configuration for controlling loads of two systems. What is different from  FIG. 18  in the aspect of input and output is that DC power as an input includes Acc power  12  linked with an accessory Acc of a vehicle and IGN power source  13  linked with the ignition (IGN) of the vehicle. For this reason, the Acc power  12  and the IGN power source  13  are input to a control power supply unit  5  via diodes D 4  and D 3 , respectively. Further, a power converting unit includes a predetermined current circuit (which has a current value obtained by dividing a voltage value, obtained by subtracting a forward voltage drop Vf of a load  3  from the IGN power source  13 , by resistance of the resistor R 3 ) configured with a resistor R 3  and a switch element SW 3  and a constant current circuit configured with a coil L 1 , a diode D 5 , a switch element SW 4 , a current detecting resistor R 4 , and a detecting unit  14 . 
       FIG. 22  illustrates an operation of the constant current circuit. When the switch element SW 4  is turned on, a current from the Acc power  12  flows through the coil L 1 , the LED  4 , the current detecting resistor R 4 , and the switch element SW 4 . When the current value becomes a predetermined current Imax, the switch element SW 4  is turned off. When the switch element SW 4  is turned off, a current of the coil L 1  flows through the LED  4 , the current detecting resistor R 4  and the diode D 5 . When the current value becomes a predetermined current value Imin, the switch element SW 4  is turned on. This operation is repeated, so that constant current control is implemented. 
     The control unit  7  that controls a plurality of loads usually controls the switch elements SW 3  and SW 4  according to the CAN communication  2  or other communications and supplies power to the loads  3  and  4  (for example, the LEDs  3  and  4 ). 
     SUMMARY 
     The power converter that controls the plurality of loads  3  and  4  can be implemented by the configurations of the conventional example illustrated in  FIGS. 18 and 21 . However, the power converting unit  8  and  9  or at least the switch element is necessary for the respective loads  3 ,  4 , and thus it is difficult to reduce the size and the cost of the lighting device. Further, a signal such as the CAN communication  2  is necessary for load control, and thus it is difficult to reduce the cost. 
     According to an embodiment of the present disclosure, a power converter receives a plurality of direct current (DC) powers, which are received in different modes, have a common ground, and have substantially the same potential and operates a plurality of loads. The power converter operates the loads according to input states of the plurality of DC powers and supplies the plurality of loads with power via at least a common switch element or a common coil. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a circuit diagram according to Embodiment 1 of the present invention. 
         FIG. 2  is an operation waveform diagram according to Embodiment 1 of the present invention. 
         FIG. 3  is an operation waveform diagram according to a modification of Embodiment 1 of the present invention. 
         FIG. 4  is an operation waveform diagram according to another modification of Embodiment 1 of the present invention. 
         FIG. 5  is a circuit diagram according to another modification of Embodiment 1 of the present invention. 
         FIG. 6  is a circuit diagram according to Embodiment 2 of the present invention. 
         FIG. 7  is an operation waveform diagram according to Embodiment 2 of the present invention. 
         FIG. 8  is a circuit diagram illustrating a modification of a power converting unit according to Embodiment 2 of the present invention. 
         FIG. 9  is a circuit diagram according to Embodiment 3 of the present invention. 
         FIG. 10  is an operation waveform diagram according to Embodiment 3 of the present invention. 
         FIG. 11  is a circuit diagram according to Embodiment 4 of the present invention. 
         FIG. 12  is a circuit diagram according to Embodiment 5 of the present invention. 
         FIG. 13  is a circuit diagram according to a modification of Embodiment 5 of the present invention. 
         FIG. 14  is a perspective diagram illustrating a circuit substrate in which an LED lighting device according to Embodiment 2 of the present invention is mounted. 
         FIG. 15  is a perspective diagram illustrating a circuit substrate in which LEDs which are loads are simultaneously mounted on a substrate on which an LED lighting device according to Embodiment 2 of the present invention is mounted. 
         FIG. 16  is a schematic cross-sectional diagram of a vehicle headlight having a lighting device of the present invention. 
         FIG. 17  is an explanatory diagram illustrating a vehicle in which a lighting device or a headlight of the present invention is mounted. 
         FIG. 18  is a circuit diagram of Conventional example 1. 
         FIG. 19  is a circuit diagram illustrating an example of a power converting unit of Conventional example 1. 
         FIG. 20  is a circuit diagram illustrating another example of the power converting unit of Conventional example 1. 
         FIG. 21  is a circuit diagram of Conventional example 2. 
         FIG. 22  is an operation waveform diagram of Conventional example 2. 
     
    
    
     DETAILED DESCRIPTION 
     (Embodiment 1) 
       FIG. 1  illustrates a circuit configuration of a power converter according to Embodiment 1 of the present invention. Headlight  26  which generates a passing beam is a load of power source  21  which is linked with a headlight switch. Power is supplied from the power source  21 , which is linked with the headlight switch, to the headlight  26  (e.g., LED) through a coil L 1 , a current detecting resistor R 4 , and a switch element SW 4 . A diode D 5  is connected in a direction in which a current by the coil L 1  is regenerated when the switch element SW 4  is turned off. A current flowing through the headlight  26  is detected by the current detecting resistor R 4  and a detecting unit  14 , and a detection signal s 1  is input to the control unit  7 . 
     A day time running light (DTRL) provides a load across power source  13  which is linked with an ignition (IGN). The day time running light (DTRL)  25  is turned on during the daytime to inform another vehicle of its presence. Power is supplied from the power source  13  linked with the ignition (IGN) to the DTRL  25  through a high side switch  22 , a resistor R 3 , and the switch element SW 4 . Detecting units  23  and  24  detect a state of the power source  13  linked with the ignition (IGN) and a state of the power source  21  linked with the headlight switch. The detection results are input to the control unit  7 . The control unit  7  detects the state of the power source  21  linked with the headlight switch and the state of the power source  13  linked with the ignition (IGN) and controls the turning ON/OFF of both loads as shown in Table 1. 
     
       
         
               
               
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
             
             
               
                 IGN power source 13 
                 OFF 
                 ON 
                 OFF 
                 ON 
               
               
                 Headlight SW power source 21 
                 OFF 
                 OFF 
                 ON 
                 ON 
               
               
                 Load 25 
                 OFF 
                 ON 
                 OFF 
                 OFF 
               
               
                 Load 26 
                 OFF 
                 OFF 
                 ON 
                 ON 
               
               
                   
               
             
          
         
       
     
       FIG. 2  illustrates a timing chart of lighting control of both loads by an input change of both powers. The operation is described below. 
     When both the IGN power source  13  and the headlight switch power source  21  are turned off, nothing is input to the control power supply unit  5 , and both loads  25  and  26  are in an OFF state. When the IGN power source  13  is turned on when both loads  25  and  26  are in the OFF state, the high side switch  22  and the switch element SW 4  are turned on by driving signals d 1  and d 2 , and the LED  25  is turned on through the resistor R 3 . In this case, the resistor R 3  is supposed to output a predetermined current limited to several milliamperes (mA) to tens of milliamperes (mA) and thus has a resistance in the tens of ohms (Ω) to thousands of ohms (Ω) (for example, 680 Ω). 
     Thereafter, when the headlight switch power source  21  is turned on, the driving signal d 1  of the high side switch  22  is turned off, so that the power supply to the LED  25  is cut off. Further, a constant current is supplied to the LED  26  by turning on/off the switch element SW 4  through the driving signal d 2  (for example, by driving at tens of kHz to hundreds of kHz). When the switch element SW 4  is turned on, a current is supplied from the power source  21  linked with the headlight switch to the LED  26  while flowing through the coil L 1 , the LED  26 , the resistor R 4 , and the switch element SW 4 . When the switch element SW 4  is turned off, a regeneration current flows through the coil L 1 , the LED  26 , the resistor R 4 , and the diode D 5 . A change in the current is detected by the resistor R 4 , and turning on/off of the switch element SW 4  is controlled according to the detection signal s 1 , so that the constant current is implemented. In this case, the resistor R 4  is used for current detection and has a resistance in the tens of milliohm (mΩ) to several ohm (Ω) to reduce a loss in the resistor R 4  (in the case of a current of 1A, a loss is 10 mW to 1 W). 
     When the power source  21  linked with the headlight is turned on in the OFF state of both loads  25  and  26 , the constant current is supplied to the LED  26  by turning on/off the switch element SW 4  in a state in which the high side switch  22  remains turned off 
     According to the present embodiment, lighting of the plurality of loads  25  and  26  can be controlled by the common switch element SW 4 , and on/off of the load is judged by the power state. Thus, communication including timing for turning on/off the load is unnecessary. Thus, the size and the cost can be reduced compared to the conventional circuit. 
     (Embodiment 1a) 
     When only the power source  13  linked with the IGN is turned on, the driving signal d 2  is always in the ON state in Embodiment 1. However, by turning on/off lighting at a frequency (for example, 10 Hz) less than 50 Hz, blinking can be recognized by the human eye, and a glittering feeling can be improved, so that a recognition degree of a driver&#39;s vehicle during daylight hours can be improved (there is influence of the afterglow or the like, but when the LED blinks at 60 Hz or more, it looks like a dimming state of DC lighting. If a deviation of a control system or the like is considered, a glittering feeling can be implemented by performing lighting at 50 Hz or less). 
     A timing chart at this time is illustrated in  FIG. 3 . Thus, it is understood that both visibility improvement by blinking control of the LED  25  and predetermined current control of the LED  26  can be implemented by the switch element SW 4 , and the size and the cost can be reduced compared to the case in which control is performed by the individual switch elements. It is understood that when only the IGN power source  13  is turned on, the same effect can be obtained even though the driving signal d 1  and the driving signal d 2  are switched. 
     (Embodiment 1b) 
     Further, when only the IGN power source  13  is turned on, by increasing the frequency of the driving signal d 2  to 60 Hz, blinking is not seen by the human eye, so that dimming lighting can be implemented. When a predetermined current is supplied to the LED  25  via the resistor R 3 , the current value depends on the magnitude of the power voltage, but by varying an On duty of a pulse width modulation (PWM) according to the power voltage, it is possible to have substantially the same current during a predetermined time and make a light flux of the LED  25  substantially the same. In an example of  FIG. 4 , as the power voltage decreases, the On duty increases. In this disclosure, a circuit that applies a predetermined current using a resistor also includes the above described control. 
     (Embodiment 1c) 
     In Embodiment 1, the LED is described as the load, but it is understood that the same effect can be obtained even when a halogen lamp  27  is used as the load instead of the LED  25  as illustrated in  FIG. 5 . In this case, the resistor R 3  may be removed. 
     Further, in Embodiment 1, the high side switch  22  is involved in supplying the power from the power source  13  linked with the IGN to the LED  25 , but the current may be supplied without the high side switch  22  as illustrated in  FIG. 5 . In this case, when both the power source  21  linked with the headlight and the power source  13  linked with the IGN are turned on, the switch element SW 4  is turned on/off to apply constant current to the LED  26 . Thus, the halogen lamp  27  is turned on/off at a high frequency (tens of kHz or more), so that the halogen lamp  27  can be turned on in the dimming lighting state. 
     Further, when the halogen lamp  27  is used as a width indicator, the power source  31  linked with the IGN functions as a power source linked with a width indicator switch, and when the headlight switch is turned on, the power from the power source linked with the width indicator switch is not input. Using this system, a state in which both power sources are turned on does not occur, and the high side switch can be removed. Accordingly, the size and the cost can be reduced. 
     (Embodiment 2) 
       FIG. 6  illustrates a circuit configuration of a power converter according to Embodiment 2 of the present invention. The same components as in Embodiment 1 are denoted by the same reference numerals, and a description thereof will be omitted. A description will be made below in connection with different points from Embodiment 1. 
     In the present embodiment, the flyback circuit illustrated in the conventional example of  FIG. 19  is used as the power converting unit for the LED  26 . The power converting unit for the LED  26  illustrated in Embodiment 1 is used as the power converting unit for the LED  25 , and a resistor RO is connected in series with a diode D 5 . A coil and a switch element of the power converting unit that supplies power to the LED  25  are configured with a primary side winding TP 1  and a switch element SW 1  of a flyback circuit that supplies to power to the LED  26 . A control unit  7  outputs a driving signal d 3  for driving the switch element SW 1 . The control unit  7  detects an output current to the LED  25  and an output current to the LED  26  by a resistor R 4  and a resistor R 1  as a detection signal s 1  and a detection signal s 2 , respectively. 
     Operation of the control unit  7  is illustrated in  FIG. 7 . When a power source  13  linked with an IGN is input, the control unit  7  detects the turning on of the power source  13  through the detecting unit  23  and outputs a PWM signal for driving the switch element SW 1  from the driving signal d 3 . Thus, the constant current is output to the LED  25 . The output current is detected by the resistor R 4  as the detection signal s 1 , and an ON time and an OFF time of the PWM signal are controlled, so that the constant current control is implemented. Further, blinking lighting of the LED  25  is performed by repetitively performing the constant current control at a certain frequency (for example, 10 Hz), a glittering feeling of the LED  25  is improved, and the recognition degree of a driver&#39;s vehicle is improved. Thereafter, when the power source  21  linked with the headlight switch is input, voltages of both terminals of the LED  25  have the same potential, so that the LED  25  is turned off. The input of the power source  21  linked with the headlight switch is detected by the detecting unit  24 , and the PWM signal for driving the switch element SW 1  from the driving signal d 3  is output. Thus, the constant current is output to the LED  26 . 
     The output current is detected using the resistor R 1  as the detection signal s 2 , and the ON time and the OFF time of the PWM signal are controlled, so that the constant current control is implemented. Thereafter, the PWM signal of the driving signal d 3  is switched in tandem while turning on/off of the headlight switch. When the IGN power source  13  is turned off in a state in which both the IGN power source  13  and the power source  21  linked with the headlight switch are turned on, a reverse voltage is applied to the LED  25 , but the LED  25  remains turned off. When the power source  21  linked with the headlight switch is turned on in a state in which both the IGN power source  13  and the power linked with the headlight switch are turned off, the LED  26  is subjected to the constant current control by the driving signal d 3 . 
     Through the above described circuit configuration and control, it is possible to share the switch element and the coil which are relatively large-scale components in the power converting unit for controlling the outputs to the LED  25  and the LED  26 . Thus, both loads can be controlled by the same switch element and coil, and thus the size and the cost of the lighting device can be reduced. 
     Typically, the power source  21  linked with the headlight switch is turned on in a state in which the IGN power source  13  is turned on. In this case, both an anode side and a cathode side of the LED  25  are connected to the power sources, and potentials of both sides become equal at a vehicle battery voltage (several voltages to a score of voltages), so that a voltage applied to the LED  25  becomes zero. Thus, the LED  25  can be automatically turned off without depending on the state of the switch element SW 1 , and the communication function or the power monitoring function can be removed, so that the size and the cost can be further reduced. 
     Power of the headlight is about 35 W, and power of the DTRL is about 5 W. The flyback circuit having a boosting capability is suitable for outputting power higher than a power converting circuit having no boosting capability. Thus, the LED  26  is used as the headlight, and the LED  25  is used as the DTRL. 
     In the present embodiment, the IGN power source  13  and the power source  21  linked with the headlight switch are used as the input. However, it is understood that even when any other power source (a power source directly connected to a battery or linked with an accessory) is added to supply power to another load, or communication such as LIN/CAN is used for load control, the same effect can be obtained. Further, it is understood that even when a power source is not added but switched (a power source linked with the IGN becomes a power directly connected to a battery or a power source linked with an accessory), the same effect can be obtained. 
     In the present embodiment, it is understood that the LED is used as the load, but even when a light source such as a halogen lamp or a high-intensity discharge (HID) lamp is used as the load, the same effect can be obtained. It is understood that even when the power converter is for power supply to other electronic units, not the light source, the same effect can be obtained. For example, the power converter has a function as a power source for a DC/AC converter enabling an alternating current (AC) powered device to be used within a vehicle or for an engine control unit (ECU) having a higher voltage as an input. 
     In an embodiment, the constant current control is performed as a control for the LED. Even when control such as constant voltage control or constant power control is performed instead of the constant current control, the same effect can be obtained. 
     Further, it is understood that even when a circuit of the resistor R 4 , the transformer T 1 , the switch element SW 1 , the diode D 1 , and the condenser C 2  constitute a circuit illustrated in  FIG. 6 , an effect which is the same as that of the circuit of  FIG. 8  can be obtained. In  FIG. 8 , a coil TP 1 ′ is used which is further wound in the same direction as the primary side winding TP 1 . Thus, it is possible to easily increase an inductance value of the coil when the LED  25  is turned on and to facilitate predetermined current control. 
     (Embodiment 3) 
       FIG. 9  illustrates a circuit diagram of Embodiment 3 of the present invention. The same components as in Embodiment 2 are denoted by the same reference numerals, and thus a description thereof will be omitted. A description is made below in connection with different points from Embodiment 2 ( FIG. 6 ). 
     The LED  26  is replaced with a HID lamp  33 . In order to turn on the HID lamp  33 , an igniter  32  for applying a high voltage pulse is installed ahead of the HID lamp  33 . In order to turn on the HID lamp  33  by a rectangular wave, a full bridge inverter  31  for converting an output of the flyback circuit into the rectangular wave is installed behind the flyback circuit. A detection signal s 3  for detecting a lamp voltage is input to the control unit  7 . Driving signals d 5  and d 6  for controlling the full bridge inverter  31  are output from the control unit  7 . 
     A circuit for applying a predetermined current to the LED  25  includes three components, a resistor R 5 , a coil TP 1 , and a switch element SW 1  which are installed in series with the LED  25 . In this case, a resistance value is in a range of hundreds of ohms (Ω) to several kilohm (kΩ) since a current has a predetermined value (a voltage value of the IGN power source  13 - a  forward voltage drop Vf of the LED  25 )/(a resistance value of the resistor R 5 ). Since control for causing a predetermined current to flow in the resistor R 5  is realized by the resistor R 5 , the detection signal s 1  for the LED current, the detecting unit  14 , and the current detecting resistor R 4  are not provided, unlike other embodiments. 
     An operation of the control unit  7  is illustrated in  FIG. 10 . When the power source  13  linked with the IGN is input, the control unit  7  detects turning on of the IGN power source  13  through the detecting unit  23  and outputs the PWM signal for driving the switch element SW 1  by the driving signal d 3 . At this time, the PWM signal is an ON/OFF signal of tens of Hz (for example, 10 Hz) so that the driver&#39;s vehicle is made more visible by highlighting the glittering feeling by blinking the LED  25 . Thus, a predetermined current is supplied to the LED  25   
     Thereafter, when the power source  21  linked with the headlight switch is input, voltages of both terminals of the LED  25  have the same potential, and thus the LED  25  is turned off. The input of the power source  21  linked with the headlight switch is detected by the detecting unit  24 , and the PWM signal for driving the switch element SW 1  by the driving signal d 3  is output (when the HID lamp  33  is turned on, driving is performed at tens of kHz to hundreds of kHz). By varying on/off of the PWM signal by the values of the detected lamp voltage and lamp current, constant power is supplied to the HID lamp  33 . Another control such as a pulse output at the start time is necessary for turning on the HID lamp  33 , but a description thereof will be here omitted. 
     Thereafter, the PWM signal of the driving signal d 3  is switched in tandem with turning on/off of the headlight switch. When the IGN power source  13  is turned off in a state in which both the IGN power source  13  and the power source  21  linked with the headlight switch are turned on, a reverse voltage is applied to the LED  25 , but the LED  25  remains off. When the headlight switch is turned on in a state in which both the IGN power source  13  and the power source  21  linked with the headlight switch are turned off, only the HID lamp  33  is controlled by the driving signal d 3 . 
     Through the above described circuit configuration and control, it is possible to share the switch element and the coil which are relatively large-scale components in the power converting unit for controlling the outputs to the LED  25  and the HID lamp  33 . Thus, both loads can be controlled by the same switch element and coil, and thus the size and the cost of the lighting device can be reduced. 
     Typically, the headlight switch is turned on in a state in which the IGN power source is turned on. In this case, both an anode side and a cathode side of the LED  25  are connected to the power, and potentials of both sides become equal at a vehicle battery voltage (several voltages to a score of volts), so that a voltage applied to the LED  25  becomes zero. Thus, turning off can be automatically performed without depending on the state of the switch element SW 1 , and the communication function or the power monitoring function can be removed, so that the size and the cost can be further reduced. 
     Further, the circuit for turning on the LED  25  can be simplified compared to Embodiment 2, and thus the size and the cost can be further reduced. 
     In the present embodiment, when the LED  25  is turned on, blinking lighting is performed in order to improve the recognition degree of the driver&#39;s vehicle. However, it is understood that when only the power source  13  linked with the IGN is input, even though lighting is constantly performed or dimming lighting is performed at a higher frequency, the same effect can be obtained. 
     (Embodiment 4) 
       FIG. 11  illustrates a circuit diagram of Embodiment 4 of the present invention. The same components as in Embodiment 2 are denoted by the same reference numerals, and thus a description thereof will be omitted. A description will be made below in connection with different points from Embodiment 2 ( FIG. 6 ). 
     In the present embodiment, the flyback circuit of Embodiment 2 (illustrated in  FIG. 19 ) is replaced with a boosting circuit using an auto transformer illustrated in  FIG. 20 . A lighting circuit of the LED  25  has the circuit configuration of Embodiment 3. 
     Through the above configuration, it is possible to share the switch element SW 2  and the coil T 2  which are relatively large-scale components in the power converting unit for controlling the outputs to the LED  25  and the LED  26 . Thus, both loads  25  and  26  can be controlled by the same switch element SW 2  and coil T 2 , and thus the size and the cost of the lighting device can be reduced. 
     Typically, the headlight switch is turned on in a state in which the IGN power is turned on. In this case, both an anode side and a cathode side of the LED  25  are connected to the power, and potentials of both sides become equal at a vehicle battery voltage (several volts to a score of volts), so that a voltage applied to the LED  25  becomes zero. Thus, turning off can be automatically performed without depending on the state of the switch element SW 2 , and the communication function or the power monitoring function can be removed, so that the size and the cost can be further reduced. 
     Further, the circuit for turning on the LED  25  can be simplified compared to Embodiment 2, and thus the size and the cost can be further reduced. 
     In the present embodiment, the boosting circuit using the auto transformer is used. However, it is understood that even when any other converter circuit such as a boost chopper circuit having no secondary side winding TS 2 , a forward type converter, a choke circuit, or a SEPIC (single-ended primary inductance converter) circuit is used, the same effect can be obtained. 
     (Embodiment 5) 
       FIG. 12  illustrates a circuit diagram of Embodiment 5 of the present invention. The same components as in Embodiment 2 are denoted by the same reference numerals, and thus a description thereof will be omitted. A description will be made below in connection with different points from Embodiment 2 ( FIG. 6 ). 
     In the embodiment, the diode D 1  is removed from the flyback circuit that supplies power to the LED  26 , and a switch element SW 7  is added. A body diode of the added switch element SW 7  is added to have the same effect as the removed diode D 1 . 
     A circuit for applying a predetermined current to the LED  25  includes four components, a resistor R 5 , a diode D 6 , a coil TS 1 , and a switch element SW 7 . In this case, a resistance value is in a range of hundreds of ohm (Ω) to several kilohm (kΩ) to limit a current. 
     The diode D 6  is connected in series with the LED  25 , and the resistor R 6  is connected in parallel with the LED  25 , so that a large reverse voltage is not applied to the LED  25  when the output voltage of the flyback circuit increases. 
     By employing this configuration, when the LED  26  is turned on, the switch element SW 7  is turned off, and the flyback circuit is configured using the body diode of the switch element SW 7 . Thus, the LED  26  is turned on by the constant current. When the LED  25  is turned on, the switch element SW 7  is turned on, and a predetermined current is applied to the LED  25  via the resistor R 5 . Further, blinking of the LED  25  is performed (at the frequency of 10 Hz) by applying or not applying the predetermined current by the coil TS  1  and the switch element SW 7 . 
     Further, when the LED  26  is turned on by the flyback circuit, the switch element SW 7  is not constantly turned off, but when the switch element SW 1  is turned off, the switch element SW 7  is turned on, so that synchronization rectification of the flyback circuit can be performed. As a result, efficiency can be further improved compared to the case in which only the body diode is used. 
     Through the above configuration, it is possible to share the switch element and the coil which are relatively large-scale components in the power converting unit for controlling the outputs to the LED  25  and the LED  26 . Thus, both loads can be controlled by the same switch element and coil, and thus the size and the cost of the lighting device can be reduced. 
     In the present embodiment, the flyback circuit is used, but it is understood that even when any other converter circuit such as an auto transformer circuit ( FIG. 13 ) is used, the same effect can be obtained. 
     (Embodiment 6) 
       FIG. 14  illustrates a circuit substrate in which an LED lighting device as illustrated in Embodiment 2 of the present invention is used. Power is received from an input connection unit  10 , and power is output to an output connection unit  11 . In the present embodiment, since power supply units for two loads are present, a power supply to the LED  25  is separated from a power supply to the LED  26 , and the control unit  7  is installed therebetween, so that noises of the power supply units are reduced. 
     By using the circuit configuration illustrated in  FIG. 6 , the size and the cost of the substrate can be reduced. 
       FIG. 15  illustrates a circuit substrate in which the LEDs  25  and  26  which are the loads are simultaneously mounted on the substrate on which the power supply unit is mounted. In this circuit substrate, an output connection unit is configured with a pattern, and the LEDs  25  and  26  can be mounted on the same substrate as the loads. Thus, the size and the cost can be further reduced. 
     (Embodiment 7) 
       FIG. 16  illustrates a schematic cross-sectional structure of a vehicle headlight having a lighting device of the present invention. A front opening of a case  40  in which the LEDs  25  and  26  are mounted as the loads is covered with a transparent cover  41 , and a lighting device  20  of the present invention is mounted on the bottom of the case  40 . By mounting the lighting device  20  of the present invention, the size and the cost of the vehicle headlight can be reduced. 
     Further, since the single lighting device  20  can have a plurality of functions, an input connector (the input connection unit  10 ) for the vehicle headlight can be put together. 
     (Embodiment 8) 
       FIG. 17  illustrates a vehicle in which a lighting device or a headlight of the present invention is mounted. A power source  21  linked with a headlight switch and an IGN power source  13  are received, and lighting of an LED  25  as a DTRL and an LED  26  as a passing beam is controlled. 
     By mounting the lighting device or the headlight of the present invention, the size and the cost of the vehicle can be reduced. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the disclosures. Indeed, the novel organic light-emitting devices described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the disclosures. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the disclosures.