TWI403217B - Light source system with single power supply - Google Patents

Description

Light source system with single power supply

The present invention relates to a light source system, and more particularly to a light source system that shares a single power source.

Please refer to Figure 1. 1 is a schematic diagram of a prior art light source system 100. The light source system 100 includes a power supply module 110, a light emitting module 120, and a current control module 130.

The power supply module 110 includes three DC/DC converters (power supplies) 111, 112, and 113 for respectively converting an input DC voltage V _IN into DC voltages V _OUTR , V _OUTG , V _OUTB for providing illumination The module 120 is used.

The light-emitting module 120 includes three sets of Light Emitting Diode (LED) series (light-emitting load) LED _R , LED _G and LED _B. Each group of light emitting diodes may be composed of M series light emitting diodes. For example, the LED array LED _R includes M series LEDs. The LED array LED _R is composed of M series red light emitting diodes; the LED array LED _G is composed of M series green light emitting diodes; The body tandem LED _B is composed of M series blue light emitting diodes. The light-emitting diodes of each color have different forward voltages. For example, the red light emitting diode may have a forward bias of 2.4 volts, the green light emitting diode may have a forward bias of 3.1 volts, and the blue light emitting diode may have a forward bias of 3.2 volts. . Therefore, if M is set to 100, the DC voltage V _OUTR required for the LED _{array R} is 240 volts, and the DC voltage V _OUTG required for the LED array LED _G is 310 volts. The DC voltage V _OUTB required for the LED array LED _B is 320 volts.

The current control module 130 includes three constant current sources IS _R , IS _{G ,} and IS _B . Each constant current source is used to provide the same magnitude of current I _REF to the corresponding LED array LED _R , LED _G and LED _B .

Since the LEDs _R , LED _G, and LED _B require different DC voltages V _OUTR , V _{OUTG ,} and V _OUTB , the power supply module 110 requires a minimum of three DC/DC converters 111 , 112 and 113, the DC voltage V _IN can be converted into DC voltages V _OUTR , V _OUTG , V _OUTB for use by the light emitting module 120. In other words, if there are more different types of LEDs in the light-emitting module 120, the power supply module 110 needs more different DC/DC converters to generate the required voltage, resulting in cost. Rising, reducing the convenience of the user using the light source system 100.

It is therefore an object of the present invention to provide a light source system having a voltage compensation module to solve the above problems.

The present invention provides a light source system having a single power source. The light source system includes a first power source for providing a first voltage, a first light-emitting load, electrically connected to the first power source and carrying a second voltage, and emitting light according to the current flowing, and a second light-emitting The load is electrically connected to the first power source and carries a third voltage, and emits light according to the current flowing, and a voltage compensation module. The voltage compensation module includes a first voltage compensation device electrically connected to the first illumination load and carrying a fourth voltage, and a second voltage compensation device electrically connected to the second illumination load and carrying a Five voltages. The sum of the second voltage and the fourth voltage is equal to the first voltage, and the sum of the third voltage and the fifth voltage is equal to the first voltage.

The invention further provides a light source system having a single power source. The light source system includes a first power source for providing a first voltage, a first light-emitting load, electrically connected to the first power source and carrying a second voltage, and emitting light according to the current flowing, and a second light-emitting The load is electrically connected to the first power source and carries a third voltage, and emits light according to the current flowing, and the voltage compensation module. The voltage compensation module includes a transformer, a first sensing device, a second sensing device, an error amplifier, a duty cycle adjuster, and a switch. The transformer includes an input coil circuit for receiving a second power source to generate a fourth voltage. The input coil circuit includes a first predetermined number of coil turns, and a first output coil circuit electrically connected to the first light. The load includes a second predetermined coil number for providing a fifth voltage, and a second output coil circuit electrically connected to the second lighting load, including a third predetermined coil number for providing a The sixth voltage. The fourth voltage is divided by the second predetermined number of coil turns and multiplied by the first predetermined number of turns to be equal to the fifth voltage. The fourth voltage is divided by the third predetermined number of coil turns and multiplied by the first predetermined number of turns to be equal to the sixth voltage. The first sensing device is electrically connected to the first output coil circuit. The second sensing device is electrically connected to the second output coil circuit. The error amplifier includes a first end electrically connected to the first sensing device and the second sensing device, a second end for receiving a reference voltage, and an output terminal, the error amplifier is based on the error The first input end of the amplifier and the signal received by the second input end of the error amplifier output an error signal. The duty cycle adjuster is electrically connected to the output of the error amplifier for receiving the error signal to generate a switch control signal. The switch is electrically connected between the input coil circuit of the transformer and a ground terminal and the duty cycle adjuster. The open relationship turns on the input coil circuit of the transformer and the ground according to the switch control signal. The input coil circuit generates the fourth voltage when the switch turns on the input coil circuit of the transformer and the ground. The input coil circuit does not generate the fourth voltage when the switch does not conduct the input coil circuit of the transformer and the ground. The sum of the second voltage and the fifth voltage is equal to the first voltage, and the sum of the third voltage and the sixth voltage is equal to the first voltage.

Certain terms are used throughout the description and following claims to refer to particular elements. It should be understood by those of ordinary skill in the art that manufacturers may refer to the same elements by different nouns. The scope of this specification and the subsequent patent application do not use the difference of the names as the means for distinguishing the elements, but the differences in the functions of the elements as the basis for the distinction. The term "including" as used throughout the specification and subsequent claims is an open term and should be interpreted as "including but not limited to". In addition, the term "electrical connection" is used herein to include any direct and indirect electrical connection. Therefore, if a first device is electrically connected to a second device, it means that the first device can be directly connected to the second device or indirectly connected to the second device through other devices or connection means.

Please refer to Figure 2. 2 is a schematic diagram of a light source system 200 having a single power source of the present invention. As shown in FIG. 2 , the light source system 200 includes a power supply module 210 , a light emitting module 220 , a voltage compensation module 240 , and a current control module 230 .

The power supply module 210 includes a single DC/DC converter (power supply) 211 for converting an input DC voltage V _IN into a DC voltage V _OUT for use by the lighting module 220.

The light-emitting module 220 includes three sets of light-emitting diode series (light-emitting load) LED _R , LED _G and LED _B. Each group of LEDs can be composed of M series LEDs, and each group of LEDs is electrically connected to the DC/DC converter 211 to receive the voltage V _OUT . For example, the LED array LED _R includes M series LEDs. The LED array LED _R is composed of M series red light emitting diodes; the LED array LED _G is composed of M series green light emitting diodes; The body tandem LED _B is composed of M series blue light emitting diodes. The light-emitting diodes of each color have different forward biases. For example, the red light emitting diode may have a forward bias of 2.4 volts, the green light emitting diode may have a forward bias of 3.1 volts, and the blue light emitting diode may have a forward bias of 3.2 volts. . Therefore, if M is set to 100, the DC voltage V _OUTR required for the LED _{array R} is 240 volts, and the DC voltage V _OUTG required for the LED array LED _G is 310 volts. The DC voltage V _OUTB required for the LED array LED _B is 320 volts.

The current control module 230 includes three constant current sources IS _R , IS _{G ,} and IS _B . . Each constant current source is electrically connected to the corresponding LED array LED _R , LED _G and LED _B for providing the same magnitude of current I _REF to the corresponding LED array LED _R , LED _G and LED _B. For example, the constant current source IS _{R is} electrically connected to the LED array LED _R to provide a current I _REF to the LED array LED _R .

The voltage compensation module 240 includes three voltage compensation devices 241, 242, and 243. The voltage compensating device 241 is electrically connected between the LED array _R and the constant current source IS _R ; the voltage compensating device 242 is electrically connected between the LED array LED _G and the constant current source IS _G ; The voltage compensation device 243 is electrically connected between the LED array LED _B and the constant current source IS _B . The voltage compensating devices 241, 242 and 243 are respectively used for voltage compensation of the LED series LED _R , LED _G and LED _B , respectively, so that a single DC/DC converter 211 in the power supply module 210 provides The output voltage V _OUT can be shared by three different LED strings, LED _R , LED _G and LED _B. In other words, the voltage compensable by the voltage compensating device 241 is the compensating voltage V _DR , the voltage compensable by the voltage compensating device 242 is the compensating voltage V _DG , and the voltage compensable by the voltage compensating device 243 is the compensating voltage V _DB . For example, the red light emitting diode may have a forward bias of 2.4 volts, the green light emitting diode may have a forward bias of 3.1 volts, and the blue light emitting diode may have a forward bias of 3.2 volts. . Therefore, if M is set to 100, the DC voltage V _OUTR required for the LED _{array R} is 240 volts, and the DC voltage V _OUTG required for the LED array LED _G is 310 volts. The DC voltage V _OUTB required for the LED array LED _B is 320 volts. Therefore, the output voltage V _{OUT of the} DC/DC converter 211 can be set to 330 volts, and the compensation voltages V _DR , V _{DG ,} and V _DB can be set to 90, 20, and 10 volts, respectively. Desired result, illumination system 200 of the present invention the DC / DC converter voltage output can be set to 330 volts, and through voltage compensation module 240, so that each of the tandem light-emitting diode LED _R, LED _G And LED _B to share. In other words, the light source system 200 of the present invention requires only one DC/DC converter to drive different LED arrays, thereby saving cost. In other words, through the design of the voltage compensation module 240, each of the light emitting diodes can share the same voltage source to improve the convenience of the light source system 200.

Please refer to Figure 3. Figure 3 is a schematic diagram of a voltage compensation module 240 in accordance with a first embodiment of the present invention. As shown in FIG. 3, the voltage compensating devices 241, 242, and 243 can be realized by Zener diodes ZN _R , ZN _{G ,} and ZN _B , respectively. According to the foregoing settings, the compensation voltages V _DR , V _{DG ,} and V _DB required for the voltage compensating devices 241, 242, and 243 are 90, 20, and 10 volts, respectively. Therefore, the breakdown voltages of the Zener diodes ZN _R , ZN _{G ,} and ZN _B can be designed to be exactly 90, 20, and 10 volts to meet the required compensation voltages V _DR , V _{DG ,} and V _DB . In this way, the voltage consumed by the LED diode _R and the Zener diode ZN _R (240 volts + 90 volts) can be exactly the same as the output voltage V _OUT (330 volts) of the DC/DC converter. The voltage consumed by the LED diode _G and the Zener diode ZN _G (310 volts + 20 volts) can be exactly the same as the output voltage V _OUT (330 volts) of the DC/DC converter; The voltage consumed by the diode series LED _B and the Zener diode ZN _B (320 volts + 10 volts) can be exactly the same as the output voltage V _OUT (330 volts) of the DC/DC converter; The power of a voltage source.

Please refer to Figure 4. Figure 4 is a schematic diagram of a voltage compensation module 240 in accordance with a second embodiment of the present invention. As shown in Fig. 4, voltage compensating devices 241, 242, and 243 can be implemented with resistors R _R , R _{G ,} and R _B , respectively. According to the foregoing settings, the compensation voltages V _DR , V _{DG ,} and V _DB required for the voltage compensating devices 241, 242, and 243 are 90, 20, and 10 volts, respectively. Therefore, the resistors R _R , R _G and RB can be set to an appropriate resistance according to the magnitude of the current I _REF such that the voltages of the resistors R _R , R _G and R _B are exactly 90, 20 and 10 volts, so that It meets the required compensation voltages V _DR , V _DG and V _DB , which means that the product of the resistance R _R and the current I _REF is equal to the compensation voltage V _DR , and the product of the resistance R _G and the current I _REF is equal to the compensation voltage. The product of the resistance of V _DG and resistor R _B and the current I _REF is equal to the compensation voltage V _DB . In this way, the voltage consumed by the LED diode _R and the resistor R _R (240 volts + 90 volts) can be exactly the same as the output voltage V _OUT (330 volts) of the DC/DC converter; The voltage consumed by the body string LED _G and the resistor R _G (310 volts + 20 volts) can be exactly the same as the output voltage V _OUT (330 volts) of the DC/DC converter; the LED diode and the resistor _B The voltage consumed by R _B (320 volts + 10 volts) is exactly the same as the output voltage V _OUT (330 volts) of the DC/DC converter; it is possible to achieve the effect of sharing a single voltage source.

Please refer to Figure 5. Figure 5 is a schematic diagram of a voltage compensation module 240 in accordance with a third embodiment of the present invention. As shown in FIG. 5, the voltage compensation module 240 can be implemented as a transformer. The voltage compensation module 240 is hereinafter referred to as a transformer 240. Transformer 240 can include an input coil circuit T _I and three output coil circuits T _R , T _{G ,} and T _B . The voltage compensating devices 241, 242, and 243 are output coil circuits T _R , T _{G ,} and T _{B , respectively} . The input coil circuit T _I is for receiving the input voltage V _IN to generate the voltage V _X ; and the voltage across the output coil circuits T _R , T _G and T _B and the voltage V _X , the input coil circuit T _I The number of turns of the winding, the number of turns of the coil wound by the output coil circuit T _R , the number of turns of the coil wound by the output coil circuit T _G , and the number of turns of the coil wound by the output coil circuit T _B are related. In this embodiment, the voltage V _IN will be equal to the voltage V _X . For example, the number of coil turns, coil circuit output generated by T _R V _DR will equal the voltage across the voltage V _X multiplied by the number of turns the output winding circuit divided by T _R T _I of the coil circuit input (V _X / N ₁ =V _DR /N ₂ , where N ₁ is the number of turns of the input coil circuit T _I and N ₂ is the number of turns of the output coil circuit T _R ). According to the foregoing settings, the compensation voltages V _DR , V _{DG ,} and V _DB required for the voltage compensating devices 241, 242, and 243 are 90, 20, and 10 volts, respectively. Therefore, the coil circuits T _I , T _R , TG , and T _B can be set to an appropriate number of turns according to the magnitude of the voltage V _X such that the output voltages of the output coil circuits T _R , T _{G ,} and T _B are exactly 90, 20 and 10 volts to meet the required compensation voltages V _DR , V _DG and V _DB . In this way, the voltage consumed by the LED array _R and the output coil circuit T _R (240 volts + 90 volts) can be exactly the same as the output voltage V _OUT (330 volts) of the DC/DC converter; The voltage consumed by the diode string LED _G and the output coil circuit T _G (310 volts + 20 volts) can be exactly the same as the output voltage V _OUT (330 volts) of the DC/DC converter; the LED array The voltage consumed by LED _B and output coil circuit T _B (320 volts + 10 volts) can be exactly the same as the output voltage V _OUT (330 volts) of the DC/DC converter; it is possible to achieve the effect of sharing a single voltage source.

Please refer to Figure 6. Figure 6 is a schematic diagram of a voltage compensation module 250 in accordance with a fourth embodiment of the present invention. As shown in Fig. 6, voltage compensating devices 241, 242, and 243, similar to Fig. 5, can be implemented with output coil circuits T _R , T _{G ,} and T _B , respectively. The voltage compensating device 250 is different from the voltage compensating device 240 disclosed in FIG. 5 in that the voltage compensating device 250 additionally adds voltage sensing devices SV _R , SV _G and SV _B , an error amplifier EA, and a duty cycle adjuster. 251 and switch SW ₁ .

The voltage sensing device SV _R can be implemented by a resistor R _SR and a diode D _SR , and is electrically connected to the output coil circuit T _R for detecting the LED array _R and the output coil circuit T _{R .} The sum of the voltage drops; the voltage sensing device SV _G can be implemented by a resistor R _SG and a diode D _SG , electrically connected to the output coil circuit T _G for detecting the LED array LED _G and The output voltage of the output coil circuit T _G is a voltage drop; the voltage sensing device SV _B can be implemented by a resistor R _SB and a diode D _SB , and is electrically connected to the output coil circuit T _B for detecting the LED The voltage drop across the sum of LED _B and output coil circuit T _B .

The error amplifier EA includes two inputs and one output. One input end of the error amplifier EA is electrically connected to the voltage sensing devices SV _R , SV _G and SV _B for detecting the voltage drop and the light emitting diode of the sum of the LED array _R and the output coil circuit T _R . The voltage drop of the sum of the body tandem LED _G and the output coil circuit T _G and the worst case of the voltage drop of the sum of the LED array LED _B and the output coil circuit T _B . The other input of the error amplifier EA is used to receive a reference voltage V _REF . The error amplifier EA generates an error signal S _ER based on the received signal.

The duty cycle adjuster 251 is configured to generate a switch control signal S _PWM according to the error signal S _ER . The switch control signal S _PWM can be a pulse width modulation signal. That is to say, the switch control signal S _PWM can be a periodic signal having a period of T _D . In one cycle of the switching control signal S _PWM , the ratio of the high voltage level to the low voltage clamping is adjustable, meaning that the duty ratio of the switching control signal S _PWM is adjustable.

_A switch SW electrically connected between a bias voltage source V _SS (ground) and the input coil circuit T _I, according to the switching control signal S _PWM, the input coil circuit T _I bias source is electrically connected to V _SS . When out switch SW ₁ according to the switching control signal S _PWM is turned on (conducting), T _I circuit electrically connected to the input coil bias source V _SS, so T _I when the input coil circuit voltage generated by the input voltage V _X would V _IN , and the voltages generated by the output coil circuits T _R , T _{G ,} and T _B are also V _DR , V _{DG ,} and V _DB ; conversely, when the switch SW ₁ is turned off (non-conducting) according to the switch control signal S _PWM , The electrical connection between the input coil circuit T _I and the bias source V _SS is broken, so that the voltage V _X generated by the input coil circuit T _I is zero at this time, and the output coil circuits T _R , T _G and T _B are generated. The voltage is also zero.

According to the above design, the average compensation voltages V _DR , V _{DG ,} and V _DB can be adjusted by adjusting the duty ratio of the switch control signal S _PWM . Since the forward bias of the light-emitting diode changes rather than a constant value when the temperature rises, the above design can thus change the magnitude of the compensation voltage, so that the output voltage V _{OUT of the} DC/DC converter 211 can still be applied. A series of light-emitting diodes in the case of a rise in temperature. More specifically, the voltage compensation module 250 can dynamically change the compensated voltage as the forward voltage of the LED changes, and the application range of the voltage compensation module 250 can be further improved.

In summary, the light source system provided by the present invention can effectively utilize the voltage compensation module to compensate the voltage difference between the LED strings, so that the LED series can share the same power source. Reduce the overall cost of the lighting system and provide greater convenience.

The above are only the preferred embodiments of the present invention, and all changes and modifications made to the scope of the present invention should be within the scope of the present invention.

100, 200. . . Light source system

110, 210. . . Power supply module

111, 112, 113, 211. . . DC/DC converter

120, 220. . . Light module

130, 230. . . Current control module

240, 250. . . Voltage compensation module

241, 242, 243. . . Voltage compensation device

251. . . Work cycle adjuster

LED _R , LED _G , LED _B . . . Light-emitting diode series

IS _R , IS _G , IS _B . . . Constant current source

I _REF . . . Current

V _IN , V _OUTR , V _OUTG , V _OUTB , V _OUT , V _SS , V _DR , V _DG , V _DB , V _X , V _REF . . . Voltage

ZN _R , ZN _G , ZN _B . . . Zener diode

R _R , R _G , R _B , R _SR , R _SG , R _SB . . . resistance

D _SR , D _SG , D _SB . . . Dipole

T _I , T _R , T _G , T _B . . . Coil circuit

SV _R , SV _G , SV _B . . . Voltage sensing device

SW ₁ . . . switch

EA. . . Error amplifier

S _ER . . . Error signal

S _PWM . . . Switch control signal

Figure 1 is a schematic illustration of a prior art light source system.

Figure 2 is a schematic illustration of a light source system having a single power source of the present invention.

Figure 3 is a schematic diagram of a voltage compensation module in accordance with a first embodiment of the present invention.

Figure 4 is a schematic diagram of a voltage compensation module in accordance with a second embodiment of the present invention.

Figure 5 is a schematic diagram of a voltage compensation module in accordance with a third embodiment of the present invention.

Figure 6 is a schematic diagram of a voltage compensation module in accordance with a fourth embodiment of the present invention.

200. . . Light source system

210. . . Power supply module

211. . . DC/DC converter

220. . . Light module

230. . . Current control module

240. . . Voltage compensation module

241, 242, 243. . . Voltage compensation device

LED _R , LED _G , LED _B . . . Light-emitting diode series

IS _R , IS _G , IS _B . . . Constant current source

I _REF . . . Current

V _IN , V _OUT , V _SS , V _DR , V _DG , V _DB . . . Voltage

Claims (12)

A light source system having a single power source, comprising: a first power source for providing a first voltage; a first light-emitting load electrically connected to the first power source and carrying a second voltage, and according to the current flowing a second illuminating load, electrically connected to the first power source and carrying a third voltage, and illuminating according to the current flowing; and a voltage compensation module comprising: a first voltage compensating device, electrically connected The first illuminating load is loaded with a fourth voltage; and a second voltage compensating device is electrically connected to the second illuminating load and carries a fifth voltage; wherein the sum of the second voltage and the fourth voltage is equal to The first voltage, the sum of the third voltage and the fifth voltage is equal to the first voltage. The light source system of claim 1, wherein the first voltage compensating device comprises a first Zener diode having a breakdown voltage equal to the fourth voltage; the second voltage compensating device comprising a second The Zener diode has a breakdown voltage equal to the fifth voltage. The light source system of claim 1, wherein the first voltage compensating device comprises a first resistor, a product of a resistance of the first resistor and a current flowing through the first resistor is equal to the fourth voltage; the second The voltage compensating device includes a second resistor, and the product of the resistance of the second resistor and the current flowing through the second resistor is equal to the fifth voltage. The light source system of claim 1, wherein the voltage compensation module comprises a transformer, the transformer comprising: an input coil circuit for receiving a second power source to generate a sixth voltage, the input coil circuit comprising a first a predetermined number of coil turns; a first output coil circuit for the first voltage compensating device, the first output coil circuit including a second predetermined coil number; and a second output coil circuit for For the first voltage compensation device, the second output coil circuit includes a third predetermined number of turns of the coil; wherein the sixth voltage is divided by the second predetermined number of turns and multiplied by the first predetermined number of turns The fourth voltage; wherein the sixth voltage is divided by the third predetermined number of turns and multiplied by the first predetermined number of turns to be equal to the fifth voltage. The light source system of claim 4, wherein the first power source is a DC/DC converter for converting the voltage output by the second power source to the first voltage. The light source system of claim 1, further comprising: a first constant current source electrically connected to the first illuminating load for providing a first predetermined current; and a second constant current source electrically connected The second illuminating load is used to provide a second predetermined current. The light source system of claim 1, wherein the first illuminating load and the second illuminating load are a series of light emitting diodes. A light source system having a single power source, comprising: a first power source for providing a first voltage; a first light-emitting load electrically connected to the first power source and carrying a second voltage, and according to the current flowing a second light-emitting load, electrically connected to the first power source and carrying a third voltage, and emitting light according to the current flowing; and a voltage compensation module comprising: a transformer, comprising: an input coil circuit, For receiving a second power source to generate a fourth voltage, the input coil circuit includes a first predetermined number of coil turns; a first output coil circuit electrically connected to the first light-emitting load, comprising a second predetermined coil The number of turns is used to provide a fifth voltage; and a second output coil circuit is electrically connected to the second illuminating load, and includes a third predetermined number of coil turns for providing a sixth voltage; wherein the fourth Dividing the voltage by the second predetermined number of turns and multiplying the first predetermined number of turns by the fifth voltage; wherein the fourth voltage is divided by the third predetermined number of turns and multiplied by the first pre- The number of coil turns is equal to the sixth voltage; a first sensing device is electrically connected to the first output coil circuit; a second sensing device is electrically connected to the second output coil circuit; and an error amplifier The first terminal is electrically connected to the first sensing device and the second sensing device; a second terminal is configured to receive a reference voltage; and an output terminal is configured according to the error amplifier The first input end and the signal received by the second input end of the error amplifier output an error signal; a duty cycle adjuster is electrically connected to the output end of the error amplifier for receiving the error signal And generating a switch control signal; and a switch electrically connected between the input coil circuit of the transformer and a ground terminal and the duty cycle adjuster, wherein the open relationship is based on the switch control signal to turn on the transformer An input coil circuit and the ground end; wherein the input coil circuit generates the fourth voltage when the switch turns on the input coil circuit of the transformer and the ground end; Second voltage and the fifth voltage equals the first voltage, the third voltage and the sixth voltage is equal to the first voltage. The light source system of claim 8, wherein the first sensing device comprises a first resistor and a first diode electrically connected to the first output coil circuit and the first input of the error amplifier The second sensing device includes a second resistor and a second diode electrically coupled between the second output coil circuit and the first input of the error amplifier. The light source system of claim 8, wherein the first power source is a DC/DC converter for converting the voltage output by the second power source to the first voltage. The light source system of claim 8, further comprising: a first constant current source electrically connected to the first illuminating load for providing a predetermined current; and a second constant current source electrically connected to the A second illuminating load is used to provide the predetermined current. The light source system of claim 8, wherein the first illuminating load and the second illuminating load are a series of light emitting diodes.