TW201034518A - Lamp driving system - Google Patents

Abstract

A lamp driving system includes a first driving module including a first transformer, a first capacitor and a first current detecting circuit. The first transformer includes a first primary side and a first secondary side having a first terminal and a second terminal. The first terminal is connected to one terminal of a lamp. One terminal of the first capacitor is connected to a connecting point between the first terminal and the lamp. The first current detecting circuit is constituted by several passive components, and disposed between the second terminal and the other terminal of the capacitor to form a first detecting point therebetween. A first voltage detected at the first detecting point is proportional to the lamp-end current without any current component of the parasitic capacitance.

Description

201034518 VI. Description of the invention: [Technical field to which the invention pertains] The present invention relates to a lamp driving system, and more particularly to a lamp driving system for driving a cold cathode lamp. [Prior Art] FIG. 1 is a circuit diagram of a conventional cold cathode lamp driving system in which a driving circuit 12 is connected to a primary side of a transformer 14, and a cold cathode fluorescent lamp ® 19 is connected to a secondary side of a transformer 14. The drive circuit 12 converts the DC power source into an AC power source, and supplies it to the cold cathode lamp tube 19 via the transformer 13. The cold cathode lamp 19 is driven at a high voltage and high frequency to cause a leakage current Ic' of the stray valley Cp at the high voltage side of the lamp. The leakage current Ic is an inrush current proportional to the electric power and frequency of the driving lamp. The current on the low voltage side of the lamp is in phase with the lamp voltage, which is the current component that produces real power. Since the cold cathode lamp 19 itself has a temperature change due to the environment or the lighting time, the same tube end current IL has a different lamp voltage as the temperature changes, and the higher the temperature, the lower the voltage. As shown in Figure 1, when the low voltage side of the lamp is directly grounded, the current feedback is taken from the low voltage side. The feedback component includes the tube end current II and the leakage current Ic. Because the leakage current Ic changes with temperature, the feedback control is controlled. The total current lB=lL+Ie does not change, because Ic will be affected by temperature, and the tube end current iL will also change in the opposite direction. Therefore, the brightness of the tube will be different and the fixed value cannot be maintained. 2 is a schematic diagram showing the current waveform of the high and low voltage sides of the cold cathode lamp tube 19 of FIG. 1. The leakage current Ic is a capacitive phase inrush current, the phase leads the resistance tube end current lL90 degrees, and the tube end current II phase and the tube The voltages are in phase. 3 is a circuit diagram of another conventional lamp driving system. In the lamp driving system 201034518, the inverter 20 includes a driving circuit 22 and a transformer 24, and the voltage output from the inverter 20 is Vcut, and the output current is I() ut. A Pulse-Width Modulation (PWM) controller 26 generates a feedback control signal to the drive circuit 22 based on the current IQUt from the secondary side of the transformer 24 to regulate the output of the inverter 20. Since the cold cathode lamp 29 has stray capacitances (:! and C2i, C22...Gn, the current iQUt includes the lamp current II and the stray capacitance current 1, and I2. The feedback control sampling circuit includes current RMS sampling. The controller 28 and the switch 27 sample the current effective value of the current 1. The stray capacitance current component ιι + ι2 of the current RMS value is minimum, so the lamp current component IL is relatively close to the current Lut. In order to obtain the current effective value, the lamp driving system includes a switch 27 coupled between the secondary side of the transformer 24 and the PWM controller 26, and the input of the current RMS sampling controller 28 is connected to the cold cathode lamp 29 The high-voltage end, the output end is coupled to the switch 27. The current RMS sampling controller 28 generates a sampling control signal to the switch 27 according to the voltage of the high-voltage end of the cold cathode lamp 29 to control the switching. Figure 4 shows the current of Figure 3 is effective. The block diagram of the value sampling controller, the current RMS sampling controller 28 includes a divider 282 and a peak value extraction circuit 284. The voltage V{jut of the high voltage end of the lamp is divided by the voltage divider 282, and the knife is cut. K after pressing The electric dust peak detecting circuit 284 outputs a sampling control signal by the voltage peak detecting circuit 284 to control the opening and closing of the switch 27 for sampling. Figure 5 is a schematic diagram of the high and low voltage current waveforms of the cold cathode lamp. The side current sampling circuit is used to detect the current on the secondary side, and the phase of the phase current of the phase current of the electric current is increased by the phase of the current phase (10) degrees, and the leakage current Ih of the lamp voltage V°ut at the peak value is Zero-time sampling and feedback, so that the feedback current only contains the tube beam current IL, therefore, the leakage current 11+12 will not affect the control of the tube end current h even if it changes due to temperature, and it can maintain the same temperature at different temperatures. The brightness of this lamp driving system is two. () In order to feedback the sampling control circuit, it is necessary to use the operational amplifier (0P) and switch with the switch T, the circuit is more complicated and the teaching price is higher. The triggering reference I needs to be lower than the lowest voltage of the lamp, and the sampling time ΔT has a wide width, so that the leakage current component is still contained in the interval of Δτ (as shown in FIG. 5), which affects the accuracy of the peak current sampling. SUMMARY OF THE INVENTION In view of the above problems, the object of the present invention is to provide a lamp driving system, which first includes a first driving die circuit having a first current debt measuring circuit, and the first electrical circuit is composed of a plurality of passive components The composition, and the formation - side = the voltage of the debt measurement point is only proportional to the tube current at the end of the tube to stabilize the brightness of the tube. The first purpose is the above-mentioned purpose 'this case proposes a kind of lamp driving system, The first driving module includes a first driving module, and includes a first transformer, a first capacitor, and a first current detecting circuit. The transformer includes a first one. The secondary side and the first secondary side, the first two: two have a first end and a second end 'the first end is connected to one side of the tube. One end of the first # is connected to the junction of the first end and the lamp. The current detecting circuit 201034518 is composed of a plurality of passive components disposed between the second end and the other end of the first capacitor, and generates a first detecting point therebetween. The first detection point detects a first voltage, and the first voltage is only proportional to the tube current of the tube* and has no capacitance current component. In the first embodiment of the present invention, the other end of the lamp is grounded. In a second embodiment of the present invention, the lamp drive system includes a second drive module coupled to the other end of the lamp. According to the above description, the lamp driving system of the present invention comprises at least one driving module having a current detecting circuit, wherein the current detecting circuit is composed of a plurality of passive components and forms a detecting point due to the detecting point. The voltage is only proportional to the tube current at the end of the tube, so that the lamp driving system of the present invention can accurately and stably control the brightness of the tube. The current detecting circuit is composed of only a plurality of passive components, and the circuit is simple, and the cost can be saved. [Embodiment] Hereinafter, a lamp driving system according to an embodiment of the present invention will be described with reference to the related drawings. First Embodiment Fig. 6A is a circuit diagram of a lamp driving system of a first embodiment of the present invention. The lamp driving system 3 is used to drive the lamp tube 37. The lamp tube 37 is a cold cathode lamp tube (CCFL), which is a linear tube or a U-shaped tube. The lamp driving system 3 includes a first driving module, and the first driving module mainly includes: a first transformer 34, a first capacitor C1, and a first current detecting circuit 38. The first transformer 34 includes a first primary side and a first secondary side, the first secondary side has a first end and a second end, and the first end is connected to one of the lamps 37 on the side of the 201034518 side of the lamp 37 The first end is provided to provide an alternating current having a first phase. The first capacitor C1 is a spectral capacitor, and its end is connected to the junction of the first end and the bulb 37. The first current detecting circuit buckle is composed of a plurality of passive 7L pieces, one end of which is connected with the second end, and is connected with the other end of the first capacitor C1, and generates a first detecting point, wherein the first - Make point _ to the first voltage, the first - electric dust ~ if the current is at the end of the tube of the tube 37 ... there is no capacitive current component.

The first current side circuit 38 includes a first resistor R1, a second R2, and a first voltage differential voltage unit 381. The first transformer=one end is grounded through a first resistor, and the first first resistor R2 is grounded to a 'first-voltage differential. The first unit of the voltage unit 2=the second transformer 34 is connected to the first resistor ;=; the first: the other end of the voltage differential pressure unit 381 and the second connection of the second resistor 9 connected to the second resistor R2 The other end of the second resistor R3 is connected to the second connection point, and the other end of the third resistor R3 is connected to the first detection point. The first voltage VSenl is only proportional to the end current h of the material 37, that is, the current of the material effect resistance of the ship, and the current component of the material capacitor. The theoretical derivation is as follows. The resistance values of the third resistor 趵 and the fourth resistor R4 in the present case are approximately equal, and the resistance values of the third resistor R3 and the fourth resistor R4 are greater than the electric power P of the first and second electric & R1 AR2 and the value rih2 . As shown in FIG. 6A, the current iie flowing through the first electric (four) also flows through the second resistor r2. 8 201034518 ^ is the stray current through the stray capacitance C2 of the lamp tube 37, and both currents are received by the lamp The tube temperature changes and the reverse current flows through the 116ri electric catch as 1C1+1C2+U. Since lci and ic2 are in phase, the first electric yseni can be proportional to the end current U of the tube π by adjusting the large j of Η and r2, regardless of the temperature of the tube. Therefore, the voltage of the first connection point can be expressed by equation (1). VR1 = -(iL+ici+ic2) · rl ..................... (1) The voltage at the first connection point yR2 can Equation (2) represents.

Vr2 — ic2 · r2 ......... know....................................... ..... (2) Therefore, the voltage value Vsenl of the first detecting point can be expressed by equation (3).

Vsenl = VR1+〇.5(VR2-VR1) ξ 〇. 5[-(iL+ic1+i〇2) · rH ic2 . r2] .................. ..................................... (2) Want to eliminate Vsenl The capacitance current component must be (ici+ic2) · rl= ic2 · r2 ................................ .............(4) Let r2<<l/c〇cl ' where ω is the angular frequency of the alternating current (angUiar frequency) ' cl is the capacitance value of the first capacitor C1, c2 It is the capacitance value of the equivalent stray capacitance C2 of the lamp tube 37. In · 1/cocl s iC2 · l/(〇C2 ..............................(5) Let rl-[ic2/(ici+ic2)]·γ2, ie rl three [c2/(cl+c2)].r2 (6) then Vsenl2-〇.5iL. rl .... .............................(7) Therefore, the resistance value rl of the first resistor R1 is determined by the equation ( 6) defined. The first voltage Vsenl is defined by equation (7). Therefore, the resistance values ri and r2 of the first and second resistors R1 and R2 are moderately adjusted, so that the first voltage Vsenl can only be combined with the first resistor R1. The resistance value rl is proportional to the tube end current iL. 9 201034518 The lamp driving system 3 further includes a driving circuit 32 connected to the first-second side of the first transformer 34, and the driving circuit 32 is used for converting the DC power source into an AC power source. 'Provide AC power to the first-second side of the first transformer 34. The lamp driving system 3 further includes a rectifying and dividing unit 35 for rectifying and dividing the first voltage Vsen1 and generating a first voltage signal ν < Fig. 6B is a circuit diagram of the rectifying and dividing unit of Fig. 6A, the rectifying and dividing unit 35 includes a diode D and a balancer 351, and the voltage divider 351 includes a fifth resistor Ra, an eighth resistor Rb, and chopper The first voltage vseni of the capacitor G' is rectified and filtered by the diode D, filtered, and the voltage divider 351 generates a first voltage signal V<n. The anode of the diode D is connected to the first detection point. The cathode of the diode is connected to one end of the fifth resistor Ra, the other of the fifth resistor Ra is connected to one end of the sixth resistor Rb, the other end of the sixth resistor Rb is grounded, and the second resistor Ra and the sixth resistor are A first voltage signal ~ is generated between Rb.

The lamp driving system 3 further includes a pulse width modulation (pwM) controller 36, one end of which is connected to the rectifying and dividing unit 35 for receiving the first voltage signal Vdl, and is referenced by the pulse width modulation controller 36. In the voltage comparison, the other end of the pulse width modulation controller 36 is connected to the driving circuit 32 for outputting a control signal to the driving circuit 32, and by controlling the duty cycle of the driving circuit 32 to stably control the lamp tube. 37 real production. FIG. 7A is a circuit diagram of a lamp driving system according to a second embodiment of the present invention. The lamp driving system 4 of the second embodiment of the present invention mainly includes a first driving module and a second driving module, and the first driving mode. The group is the same as the first driving module of the first embodiment, and will not be further described. 201034518 The second drive module is connected to the other end of the lamp tube 37. The second driving module includes a second transformer 44, a second capacitor C3, and a second current detecting circuit 48. The second transformer 44 includes a second primary side and a second secondary side, and the secondary side has a third end and a second The fourth end is connected to the other side of the lamp tube 37. The first end of the first transformer 34 is used to provide alternating current with a first phase, and the third end of the second transformer 44 is used to provide In the two-phase alternating current, the first phase is different from the second phase by one hundred and eighty degrees. When the first end is ❿ positive high voltage end, the third end is negative negative high voltage end. When the first end is a negative high voltage end, the third end is a positive high voltage end. The second capacitor C3 is a resonant capacitor, and one end thereof is connected to the junction of the third end and the lamp tube 37. The second current detecting circuit 48 is composed of a plurality of passive components, one end of which is connected to the fourth end, and the other end of which is connected to the other end of the second capacitor C3, and generates a second detecting point therebetween, wherein the second The detection point detects the second voltage Vsen2, and the second voltage Vsen2 is only proportional to the tube end current it* of the lamp tube 37 has no capacitance current component. The second current detecting circuit includes a seventh resistor R7, an eighth resistor R8, and a second voltage differential voltage unit 481. The fourth end of the second transformer 44 is grounded through the seventh resistor R7, and the other end of the second capacitor C3 passes through The eighth resistor R8 is grounded, one end of the second voltage differential voltage unit 481 is connected to the third connection point of the fourth end of the second transformer 44 and the seventh resistor R7, and the other end of the second voltage difference unit 481 is connected to the second The other end of the capacitor C3 is connected to the fourth connection point of the eighth resistor R8. The second voltage differential voltage unit 481 includes a ninth resistor R9 and a tenth resistor R10. One end of the ninth resistor R9 is connected to the third connection point, and the end of the tenth resistor R10 11 201034518 is connected to the fourth connection point, and the ninth resistor R9 The other end of the tenth resistor R10 is connected to the second detecting point. The resistance values of the ninth resistor R9 and the tens resistor R10 are approximately equal, and the resistance values of the ninth resistor R9 and the tenth resistor R10 are much larger than the resistance values of the seventh and eighth resistors R7 and R8. The lamp driving system 4 further includes a rectifying and dividing unit 45 for rectifying, filtering and dividing the first and second voltages Vsen1 and Vsen2, and generating a second voltage signal VdZ. 7B is a circuit diagram of the rectifying and dividing unit of FIG. 7A, the rectifying and dividing unit 435' includes two diodes D1 and D2 and a voltage divider #451 '. The voltage divider 451 includes a fifth resistor Ra and a sixth resistor Rb. The filter capacitor Cf 'the first and second voltages vseni and vsen2 are respectively rectified and filtered by a diode (D1 or D2) (the filter is connected to one of the fifth terminals Ra of the voltage divider 451). A second voltage signal Vd2' is generated between the resistor Ra and the sixth resistor Rb. The other end of the sixth resistor Rb is grounded. The lamp driving system 4 further includes a pulse width modulation (PWM) controller 46' having one end and a rectifying voltage divider The unit 45 is connected to receive the second voltage signal Vu, which is compared with the reference voltage Vref of the pulse width modulation controller 46. The other end of the # pulse width modulation controller 46 is connected to the driving circuit 32 for rotation. A control signal is applied to the driving circuit 32 connected to the first and second transformers 34, 44 to control the brightness of the lamp 37 by controlling the duty cycle of the driving circuit 32. In summary, the lamp of the present invention a tube drive system comprising at least one drive module having electricity The detecting circuit is composed of a plurality of passive components and forms a detecting point. Since the voltage of the detecting point is only proportional to the current of the tube end of the tube, the lamp driving system of the present invention can be accurately The ground is stable to control the brightness of the lamp. 12 201034518 The flow circuit consists of only a few lion components, and the circuit is simple and early, which can save costs. The electricity is only an example 'not a restrictive one. Anything is not out of God and Fan等效 咛 等效 等效 等效 等效 等效 等效 等效 等效 等效 等效 等效 等效 等效 等效 等效 等效 等效 等效 等效 等效 等效 等效 等效 等效 等效 等效 等效 等效 等效 等效 等效 等效 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 FIG. 3 is a schematic circuit diagram of another conventional lamp tube driving system; FIG. 4 is a block diagram of the current RMS sampling controller of FIG. 3; FIG. 6 is a circuit diagram of the lamp driving system of the first embodiment of the present invention; FIG. 6 is a circuit diagram of the rectifying and dividing unit of FIG. 6;; ❹ FIG. 7Α is the second embodiment of the present invention The circuit diagram of the lamp driving system; and Fig. 7 is the circuit diagram of the rectifying and dividing unit of Fig. 7. [Main component symbol description] 12, 22: drive circuit 14, 24: transformer 19, 29: cold cathode lamp 20: change Flow device 26: PWM controller 27: Switch 28: Current RMS sampling controller 282: Voltage divider 13 201034518 284: Voltage peak detection circuit 3: Lamp drive system 32: Drive circuit 35, 45: Rectification voltage dividing unit 36: pulse width modulation controller 37: lamp 38: first current detecting circuit 4: first transformer 48: second current detecting circuit C1: first capacitor φ C3: second capacitor

Cl, C21~C22: stray capacitance IC: leakage current II, h: tube end current h, h: stray capacitance current R1: first resistor R3: third resistor 〇R7: seventh resistor R9: ninth resistor Ra : fifth resistor 381 : first voltage differential voltage unit 44 : second transformer 481 : second voltage differential voltage unit C2 : equivalent stray capacitance

Cf : filter capacitor

Cp: stray capacitance

Ih : high voltage current I out . current ici, ic2 : current R2 : second resistor R4 : fourth resistor R8 · · eighth resistor R10 : tenth resistor

Rb: sixth resistor

Rl: equivalent resistance Vsenl: first voltage

Vsen2: second voltage signal Vdl: first voltage signal

Vd2: second voltage signal Vm: voltage value of the first connection point VR2: voltage value of the second connection point VQUt: voltage △ T : sampling time 14

Claims (1)

201034518 VII. Patent application scope: 1. A lamp driving system for driving a lamp tube, comprising a first driving module, the first driving module comprising: a first dust collector comprising a first a first side and a first second side, the first secondary side has a first end and a second end, the first end is connected to one side of the tube; a first capacitor is connected at one end thereof The first end is connected to the lamp; and the first current debt measuring circuit is composed of a plurality of passive components, one end of which is connected to the second end, and the other end of which is connected to the other end of the first capacitor Connecting, and generating a first detection point therebetween; wherein the first detection point detects that one of the first voltages is only proportional to the tube current of the tube, and there is no capacitance current component. 2. The lamp drive system of claim 1, wherein the lamp is a cold cathode lamp (CCFL). 3. The lamp driving system of claim 1, wherein the lamp Φ tube is a linear tube or a U-shaped tube. 4. The lamp drive system of claim 1, wherein the other side of the lamp is grounded. 5. The lamp drive system of claim 1, wherein the first capacitor is a resonant capacitor. 6. The lamp drive system of claim 1, wherein the first end of the first transformer is to provide an alternating current having a first phase. 7. The utility model as claimed in any one of claims 1 to 6, wherein the lamp driving system 15 201034518 has a resistance two; the second current-current detecting circuit comprises a first resistor and a second one a first voltage a differential pressure unit, the first flute of the first transformer is connected to the first resistor, and the other end of the first capacitor is connected to the eighth end by the one end of the first voltage-crushing unit a first connection point of the first resistor connection, the other end of the first voltage difference I is connected to a second connection point connected to the other end of the first capacitor and the second resistor. The invention relates to the lamp driving system of claim 7, wherein the first pressure differential pressure unit comprises a third resistor and a fourth resistor, and the second power is connected to the first end. The first connection point is connected to one end of the fourth resistor, and the other end of the third resistor is connected to the first detection point at the end of the fourth resistor. 9. The invention of claim 10, wherein the resistance of the first resistor and the fourth resistor are approximately equal. The lamp driving system of claim 9, wherein the resistance values of the second resistor and the fourth resistor are much larger than the resistance values of the first and second resistors. U*, as claimed in claim 10, wherein the resistance value of the first resistor is defined by equation (1): rl=[c2/(cl+c2)] * r2 (1) where rl For the resistance value of the first resistor, r2 is the resistance value of the second resistor, cl is the capacitance value of the first capacitor, and c2 is the capacitance value of the second capacitor. 12. The lamp driving system of claim 2, wherein the first voltage is defined by equation (2): 16 201034518 wherein Vsenl is the first voltage and H is the first power (2) The value is the current value of the current at the end of the tube. The electric power is steep. 13. The lamp driving system described in the item ΐ 丨 丨 , , 驱动 驱动 驱动 驱动 驱动 驱动 驱动 驱动 驱动 驱动 驱动 驱动 驱动 驱动 驱动 驱动 驱动 驱动 驱动 驱动 驱动 驱动 驱动 驱动 驱动 灯 灯 灯 灯 灯 灯And supplying power to the first primary side of the first transformer. " 14. The lamp driving system of claim 13 includes a rectifying and dividing unit that rectifies and divides by using the first side point and the more electric dust, and generates a - electric (four) number. The lamp driving system of claim 14, wherein the rectifying and dividing unit comprises a diode and a voltage divider, wherein the component comprises a fifth resistor, a sixth resistor and a furnace. The first capacitor is filtered by the diode and the chopper capacitor is filtered by the diode and the first voltage signal is generated.益后'Product 16. The lamp driving system of claim 15, wherein the anode of the diode is connected to the first point, the second of the diode and the end of the fifth resistor And one end of the wave capacitor is connected, the other end of the capacitor is grounded, the other end of the fifth resistor is connected to one end of the second: the other end of the sixth resistor is grounded, and the fifth electric and the first The first voltage signal is generated between the six resistors. Π. For the lamp driving system described in claim 14 of the patent scope, including a pulse width modulation controller, the end and the rectifying surface army (four) pressure signal 'and the pulse width modulation control 〇 σ multi-test The voltage ratio is equal to the other, and the other 17 201034518 terminal of the 5th pulse width modulation controller is connected to the driving circuit for outputting a control signal to the driving circuit by controlling the duty cycle of the driving circuit. To control the brightness of the tube. 18. The lamp drive system of claim 13, wherein the lamp drive system comprises a second drive module coupled to the other end of the lamp. 19. The lamp driving system of claim 18, wherein the second driving module comprises: _ a second transformer comprising a second primary side and a second secondary side, the second The second side has a third end and a fourth end, the third end is connected to the other side of the lamp tube; a second capacitor is connected at one end to the junction of the third end and the lamp tube; The second current detecting circuit is composed of a plurality of passive components, one end of which is connected to the fourth end, and the other end of which is connected to the other end of the second capacitor, and generates a second detecting point therebetween; The second detection point detects a second voltage, which is only proportional to the tube current of the tube, and has no capacitive current component. 20. The lamp drive system of claim 18, wherein the first end of the first transformer is for providing an alternating current having a first phase, and the third end of the second transformer is To provide an alternating current having a second phase that is one hundred and eighty degrees out of the second phase. 21. The lamp drive system of claim 19, wherein the first end is a positive high pressure end and the third end is a negative high pressure end. The light pipe drive system of claim 19, wherein the first end is a negative high pressure end and the third end is a positive high pressure end. 23. The lamp driving system of claim 19, wherein the second current detecting circuit comprises a seventh resistor, an eighth resistor, and a second voltage differential voltage unit, the second transformer The fourth end is grounded through the seventh resistor, the other end of the second capacitor is grounded through the eighth resistor, and one end of the second voltage differential voltage unit is connected to the third end of the fourth end connected to the seventh resistor The other end of the second voltage difference unit 10 is connected to a fourth connection point connected to the other end of the second capacitor and the eighth resistor. 24. The lamp driving system of claim 23, wherein the second voltage differential pressure unit comprises a ninth resistor and a tenth resistor, and one end of the ninth resistor is connected to the third connection point One end of the tenth resistor is connected to the fourth connection point, and the other end of the ninth resistor and the other end of the tenth resistor are connected to the second detection point. 25. The lamp driving system of claim 24, wherein the resistance of the ninth resistor and the tenth resistor are approximately equal. 26. The lamp driving system of claim 25, wherein the resistance values of the ninth resistor and the tenth resistor are much larger than the resistance values of the sixth and the eighth resistors. 27. The lamp driving system of claim 19, further comprising a rectifying and dividing unit for rectifying, filtering and dividing the first and second voltages, and generating a second Voltage signal. 28. The lamp driving system of claim 27, wherein the rectifying and dividing unit comprises a diode and a voltage divider, and the voltage divider package 19 201034518 includes a fifth resistor and a sixth The resistor and a filter capacitor, the first voltage and the second voltage are respectively filtered by the diode and filtered by the filter capacitor, and connected to one end of the voltage divider to generate the second voltage signal. 29. The lamp driving system of claim 28, further comprising a pulse width modulation controller, one end connected to the rectifying and dividing unit for receiving the second voltage signal, and the pulse One of the reference voltage comparisons of the wave width modulation controller, the other end of the pulse width modulation controller is connected to the driving circuit for outputting a control signal to the driving electrical circuit, and the responsibility of controlling the driving circuit A duty cycle to control the brightness of the lamp. 20