TWI332138B - Current controlling apparatus - Google Patents

Description

I _ ^·»*-·* ·· . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The current control device that adjusts the current flowing through the LED string to adjust the brightness of the LED string is adjusted. [Prior Art] In a Light Emitting Diode (LED) backlight of a Liquid Crystal Display Television (LCD TV), a large number of LEDs are required to achieve brightness and cold cathode. The Cold Cathode Fluorescent Lamp (CCFL) is quite a specification. In the general design, in order to reduce the number of driving integrated circuits of the light-emitting diodes and the total driving current of the light-emitting diodes, the backlight of the light-emitting diode often needs to use multiple light-emitting diodes. The design circuit in which the body is lit in series. This method not only reduces the number of groups that drive the integrated circuit, but also reduces the total driving current of the light-emitting diode and further reduces the power consumption of the driving integrated circuit. However, in the manufacturing process of the light-emitting diode, it is difficult to control the cut-in voltage of each of the light-emitting diodes (that is, the lowest voltage at which the light-emitting diode is turned on) to be completely uniform. The shortcoming of the control method will accumulate the error value of the cut-in voltage of each of the light-emitting diodes, so that the current of each group of LED strings will be different due to the total cut-in voltage under the condition of a fixed input voltage. There is a difference, which causes the brightness of the LED strings of the respective groups to be different due to the current inconsistency. This phenomenon will result in uneven brightness of the backlight of the panel and uneven color. In order to solve such problems, some improvement methods using current mirrors have been proposed one after another. For example, the circuit disclosed in U.S. Patent No. 5,701,133 is an example, as shown in Fig. 1. Figure 1 shows a conventional brightness adjustment circuit. Referring to Fig. 1, the VLED in Fig. 1 is represented as a power supply voltage, GND is represented as a ground voltage ', and Vin is represented as an input signal. The circuit shown in Figure 1 is a two-stage current mirror (Current Mirror' consisting of a Bipolar Junction Transistor (BJT' shown in Figure 1). 1之2 and 1〇3), using the two current mirrors 102 and 103, the currents imi, im2, and Ic are equal to each other' to force the control of the LED string 1〇4 Electricity flow. Therefore, by using the above-described technique in a circuit having a plurality of sets of light-emitting diode strings, the amount of current of each group of light-emitting diode strings can be forced to be uniform, thereby controlling the brightness uniformity. However, 'this circuit is only an open loop control system, that is, this circuit does not have any feedback control, so the LED string in the system fails (for example, some light in the LED string) A short circuit fault occurs in the diode) 'or the error value of the total cut-in voltage of the LED string is too large (for example, because the temperature characteristics of each LED are slightly different, causing each LED to be stringed A large total cut-in voltage difference is formed after power-on. Since the system does not have feedback control, this state cannot be detected, which will cause the bipolar-substrate transistor on the current mirror to withstand a considerable voltage and The current causes the temperature of the bi-carrier junction transistor to rise, which in turn causes the bi-carrier junction transistor to be overheated, thus making the product using this technology have doubts about reliability. 1332138

99-4-29 In addition, such as U.S. Patent No. 6,556,067 and No. 66,361,4, because of the use of a current mirror, such as an open circuit control method, forcing each group of light-emitting diodes (four) current quantity system, into the brightness Uniformity control, so there are also doubts about trustworthiness. SUMMARY OF THE INVENTION An object of the present invention is to provide a current control device that uses feedback control to adjust a current flowing through a string of light-emitting elements, thereby achieving the purpose of adjusting the brightness of a light-emitting diode string, and has a high degree of reliability. . Based on the above and other objects, the present invention proposes a current control device that is adapted to control the current of the string of light-emitting elements, wherein the end of the string of light-emitting elements is electrically connected to the power supply dragon, and the current-controlled weaving includes a current adjustment unit. With the control unit. The current adjustment unit is electrically connected between the other two of the string of the light-emitting element and the ground voltage, and the current of the string of the light-emitting element is measured, and the nickname is generated according to the conduction control signal and the impedance control signal. The _ impedance value of the string and the ground voltage, which in turn controls the motor of the illuminator. The control unit is electrically connected to the current adjustment unit for comparing the values of the reference number and the feedback signal to generate a comparison result, and the current compensation is performed, and the comparison result after the completion of the current compensation is converted into a difficult money. With impedance control signals. The present invention provides a current control device for controlling the current of a plurality of light-emitting element strings, wherein the ends of the plurality of hairsprays are electrically connected to the power supply surface, and the current control device Early group and control unit. The current adjustment unit group is electrically connected; between the other end of the 70-light string and the ground voltage, 1332138 99-4-29 is used to detect the current of each of the light-emitting element strings, thereby generating a plurality of feedback letters. number. The current adjustment unit group also receives a plurality of conduction control signals and a plurality of impedance control signals, and controls one of the light-emitting element strings and the ground voltage according to one of the conduction control signals and one of the impedance control trays The impedance value between the two, in turn, controls the flow of current through the string of light-emitting elements. The control unit is electrically connected to the current adjustment unit group for receiving the reference k number and the plurality of feedback signals, and comparing the values of each feedback signal and the reference φ signal to generate a plurality of comparison results, and each will A comparison result performs current compensation, and the comparison results after the current compensation is completed are converted into the plurality of conduction control signals and the plurality of impedance control signals. According to an embodiment of the invention, the control unit comprises an error amplifier, a current compensator, an impedance controller, and a drive buffer. The error amplifier is electrically connected to the current adjustment unit for receiving and comparing the values of the reference signal and the feedback signal to generate a comparison result. The current compensator is electrically connected to the error amplifier for receiving the comparison result and outputting the current after compensating the comparison result. The impedance controller is electrically coupled to the current buffer to receive the output of the current compensator and convert the output of the current compensator into a conduction control signal and an impedance control signal. The drive buffer is electrically coupled to the impedance controller for receiving the conduction control signal and outputting it after buffering the conduction control signal. According to an embodiment of the invention, the current adjustment unit includes a MOS transistor (full name metal-oxide semiconductor transistor), a variable impedance device, a feedback unit, a first resistor, and a first - Capacitor, second capacitor, and diode. 9 1332138 I ((Yearly Amendment Replacement Page) 99-4-29 Among the transistors, the source/drain is electrically connected to the light-emitting element string ^' and the MOS transistor is operated in the linear region to be connected to the other end of the string of light-emitting elements Between the first capacitor and the first resistor is connected between the first resistor and the gate of the M〇s transistor. The second capacitor is electrically connected between the pole of the MOS transistor and the grounding money. And the anti-device is electrically connected between the control unit and the gate of the M〇S transistor to transmit the conduction control signal to the closed end of the M〇s transistor, and dynamically adjust the resistance of the variable impedance device according to the impedance control signal The value is such that the MOS transistor changes the conduction state according to the resistance value of the conduction control signal and the variable impedance device, thereby adjusting the impedance value when the M〇s transistor is turned on. The anode of the diode is electrically connected to the M〇s transistor. a gate, the cathode of the diode is electrically connected to the conduction control signal, and the feedback unit is electrically connected between the other source/drain of the transistor and the ground voltage for detecting the current of the string of the light-emitting element, and according to To generate a feedback signal. According to an embodiment of the invention, the upper The control unit includes an error amplifier, a current compensator, an impedance controller, and a drive buffer, wherein the error amplifier is electrically connected to the current adjustment unit group for receiving the reference signal and the plurality of feedback signals, and Comparing the value of each feedback signal with the reference signal to generate the plurality of comparison results. The current compensator is electrically connected to the error amplifier for receiving the plurality of comparison results described above and is comparing each comparison result After the current compensation is performed, the impedance controller is electrically connected to the current compensator for receiving the outputs of the current compensator and converting the outputs of the current compensator into the plurality of conduction control signals and the plurality of the above-mentioned conduction control signals. Impedance control signal. The drive buffer is electrically connected to the 1332138 |-----99-4-29 interface impedance controller for receiving the plurality of conduction control signals described above, and buffering the plurality of conductions The control signal is separately output. According to an embodiment of the invention, the current adjustment unit group includes a plurality of f-flow adjustment units, and each current adjustment Yuan including

MOS transistor, variable impedance device, feedback unit, first-resistance, first capacitor, second capacitor, and diode. Wherein the MOS transistor has its t-source/non-polarity electrically connected to the other end of the plurality of light-emitting element strings, and the MOS device operates in the linear region. The first resistor is electrically connected between the other end of the string of light emitting elements and the first capacitor. The first capacitor is electrically connected between the first resistor and the gate of the MOS transistor. The second capacitor is electrically connected between the gate of the MOS transistor and the ground voltage. The variable impedance device is connected between the hard-to-solve element and the gate of the MOS transistor to transmit one of the plurality of conduction control signals to the gate of the MOS transistor, and according to the plurality of impedance control signals, wherein And dynamically adjusting the resistance value of the variable impedance device, so that the M〇s electrical body changes the conduction state according to the resistance value of the conduction control relay and the variable impedance device, and the impedance value when the M0S transistor is turned on . The anode of the diode is electrically connected to the gate of the MOS transistor, and the cathode of the diode is electrically connected to the conduction control signal. The feedback unit is electrically connected between the other source/no pole of the MOS transistor and the ground voltage for detecting the power IL of the string of the light-emitting elements, and accordingly generating one of the plurality of feedback signals. The present invention utilizes the current of the light-emitting element string for feedback control, and performs current compensation on the current of the optical element string, and then converts the current-compensated π fruit into two kinds of impedances for controlling the M〇S transistor to be turned on. Value (also known as control 11

1332138 The signal of the channel size when the Mos transistor is turned on, according to the impedance value when the M〇s transistor is turned on, the current flowing through the string of the light-emitting element is adjusted, thereby achieving the purpose of adjusting the brightness of the LED string. Therefore, the present invention has a better reliability than a conventional brightness adjustment circuit using an open circuit control method such as a current mirror. The above and other objects, features, and advantages of the present invention will become more apparent <RTIgt; [Embodiment] FIG. 2 is a current control device according to an embodiment of the present invention. Referring to FIG. 2', the current control device is adapted to control the current In' flowing through the light-emitting element string 21'. In this embodiment, the light-emitting element string 210 is composed of the light-emitting diodes 211, 212-N, and the light-emitting element string One end of 210 is electrically connected to the power supply voltage VLED (ie, the first potential V. However, the light-emitting element string 21 is not limited to be composed of the light-emitting diode. The current control device includes the current adjustment unit 220 and the control unit 230. The current adjustment unit The 220 is configured to detect the current of the light-emitting element string 21〇 and generate a feedback signal FS, and control the light-emitting element string 210 and the ground voltage GND according to the conduction control signal CCS and the impedance control signal ICS (ie, the second potential) The impedance value between the 'in turn controls the current In of the light-emitting element string 21'. The control element 230 is used to receive the reference signal Vref and the feedback signal FS, and compare the values of both the reference signal Vref and the feedback signal FS to Generate a comparison knot CS, and then compare the result CS to current compensation, 12 1332138 2f ah, replace the stack page ----------- 99-4-29 and then complete the current compensation after the comparison result Cs converted into a guide Control unit CCS and impedance control signal ICS. ° Control unit 230 includes error amplifier 231, current compensator 232, impedance controller 233, and drive buffer 234. Error amplifier 231 is used to receive reference signal Vref and feedback No. fs, and compares the values of both the reference signal Vref and the feedback signal FS to generate a comparison result CS. The current compensator 232 is configured to receive the comparison result CS output by the error amplifier 231, and to make the current of the comparison result CS. The output is compensated. The impedance controller 233 is configured to receive the output of the current compensator 232 and convert the output of the current compensation unit 232 into a digital conduction control signal cc§ and an impedance control signal ICS. The conduction control signal CCS is received and outputted after the buffering of the conduction control signal CCS. The driving buffer 234 is mainly used for signal buffering and signal amplification of the conduction control signal CCS outputted by the impedance controller 233, so that the user Whether or not the drive buffer 234 is employed in the control unit 230 can be selected according to actual needs. The current adjustment unit 220 includes The MOS transistor 221, the variable impedance device 222, the feedback unit 223, the first resistor 224, the first capacitor 225, the first capacitor 226, and the diode 227. In this embodiment, the m〇S transistor 221 The NMOS is implemented, and it is assumed that the MOS transistor 221 operates in the linear region 'other' feedback unit 223 is implemented by the second resistor 228. The second resistor 228 is used to detect the current flowing from the MOS transistor 221 to the ground voltage GND, This current is converted into a signal in the form of a voltage, that is, the feedback signal FS described above. 13 1332138 ((Year, 8th correction replacement page 99-4-29 variable impedance device is used to transmit the conduction control is number CCS output to the drive buffer 234 to the gate of the MOS transistor, and according to the impedance controller 233 The output impedance control signal dynamically adjusts the resistance value of the variable impedance device 222 so that the MOS transistor 221 changes the conduction state according to the resistance values of the conduction control signal CCS and the variable impedance device 222, thereby adjusting the MOS transistor 221 when it is turned on. The impedance value, that is, the channel size of the M〇s transistor 221 is adjusted. In other words, by adjusting the channel size of the M〇s transistor 221, the current In of the light-emitting element string 21 can be controlled to adjust the light emission. Figure 3 is a partial circuit diagram of Figure 2. Figure 4 is a characteristic diagram of the M〇s transistor. The conduction control signal cCS and the impedance control signal ICS will be described below with reference to Figures 3 and 4. Referring to Fig. 3 and Fig. 4, the Rg in the current adjusting unit 22A of Fig. 3 is the resistance value of the variable impedance device 222. Flowing through The current value of the impedance device 222, vg is the voltage value at the electrical connection between the variable impedance device 222 and the driving buffer 234, and Vplt is the electrical connection between the variable impedance shirt 222 and the MOS transistor 221, and the voltage value is 'Cgd. And cgs are the capacitance values of the first capacitor 225 and the second valley 226 of FIG. 2 respectively, Rgd is the resistance value of the first resistor 224 of FIG. 2, and ICgd is the current value flowing through the first resistor 224, Vds Bay|J The voltage value between the drain and the source of the MOS transistor 221, and the vledi and the vied are respectively the electric value of the light-emitting diode 21 of FIG. 2, 212 to N. According to FIG. Show, you can sort out the following 6:

IgxRg - Vg-Vpit ......(1) 1332138 /i ί 99-4-29

Icgd = Ig ......(2)

Icgd = Cgd(dVds/dt) (3) dVds/dt = (Vg-Vplt)/(RgxCgd) (4) AVds = ((Vg-Vplt)/(RgxCgd ))At ......(5) VLED = (Vled1+Vled2+...+VledN)+Vds+VFS...(6)

Where VFS is the voltage value of the feedback signal FS, as can be known from equation (5), the size of AVds can be determined by the values of Rg and Μ. Referring to FIG. 4, when the MOS transistor enters the linear region, the voltage Vds exhibits a linear change, and the current In exhibits a fixed value. Please refer to Figure 3 again. Therefore, when the MOS transistor 221 operates in the linear region, the value of At is modulated by the conduction control signal CCS, and the value of Rg is modulated by the impedance control signal ICS, so that the impedance of the MOS transistor 221 when it is turned on can be changed. , that is, changing the channel size of the M〇s transistor, thereby controlling the Vds voltage value, and the obtained value of AVds can be used to compensate for the short circuit of the light-emitting diode or the temperature characteristics of the light-emitting diode. The variation of (vledi+vled2+.+vledN) further controls the current In of the light-emitting element string 210. Those skilled in the art can control the current of a plurality of skill strings in accordance with the spirit of the present invention and the teachings of the above embodiments, as shown in Fig. 5. Figure 5 is a current control device in accordance with another embodiment of the present invention. Please refer to the 'No. 5' current control device for controlling the current flowing through the light-emitting element strings 510, 520, and 530, respectively W2, and 13. : Picture: Show? Expressed as H, and the sum of the total currents, that is, the light-emitting element strings 51〇, 52(), and the other 15 1332138 r-page embodiment, the light-emitting element strings 510, 520, and 530 are also The light emitting diode is composed of one end of the light emitting element strings 510, 520, and 530 electrically connected to the power supply voltage VLED (ie, the first potential). However, the light-emitting element strings 510, 520, and 530 are also not limited to being composed of light-emitting diodes. This current control device includes a current adjustment unit group 540 and a control unit 550. The current adjustment unit group 54 is configured to detect currents of the light-emitting element strings 51 〇, 520, and 530, thereby generating feedback signals FSi, FS2, and FS3, respectively. The current adjustment unit group 540 also receives three conduction control signals, CCS, CCS2, and CCS, respectively, and receives three impedance control signals 'ICS> ics2 and ICS3, respectively. The current adjustment unit group 540 controls the impedance value between the light-emitting element string 51 〇 and the ground voltage GND (ie, the second potential) according to the conduction control signal CCS! and the impedance control signal ICS!, and according to the conduction control signal CCS2 and the impedance control signal. The ICS 2 controls the impedance value between the light-emitting element string 520 and the ground voltage GND, and controls the impedance value between the light-emitting element string 530 and the ground voltage GND according to the conduction control signal CCS3 and the impedance control signal ICS3. In this way, the current adjustment unit group 540 can control the current flowing through the light-emitting element strings 510, 520, and 53, respectively. The control unit 550 is configured to receive the reference signal Vref and the feedback signals FSi, FS2, and FS3' and compare the value of each feedback signal with the reference signal to generate comparison results CS!, CS2, and CS3, respectively. And the control unit 550 performs current compensation for each comparison result, and converts the comparison results CS!, CS2, and CS3 after the completion of the current compensation into the conduction control signals Wei CCSi, CCS2, and CCS3, and the impedance control signals iCSi, ICS2 and ICS3. 1332138 99-4-29 ▲ Control unit 550 includes an error amplification $% current compensator 552, an impedance controller 553, and a drive buffer 554. In this embodiment, the error amplification state 55, the current compensator 552, the impedance controller 553', and the drive driver 5M each have at least three inputs and three outputs to simultaneously process at least two sides of the § number and The processing results are output separately, in particular the error amplifier 551 requires at least four inputs to specifically receive a reference k number Vref. However, the number of input terminals and output terminals described above is not intended to limit the number of input and output terminals of the error amplifier 551, the current compensator 552, the impedance controller 5, and the drive buffer 554, and the user can actually follow the number. Need to change. The error amplifier 551 in the control unit 550 is configured to receive the reference signal Vref and the feedback signals FS!, FS2, and FS3, and compare the values of each of the feedback signals and the reference signal Vref to generate the comparison results CSi, CS2 described above. And CS3. The current compensator 552 is configured to receive the comparison results cs!, CS2, and CS3, and output them separately after making current compensation for each comparison result. The impedance controller 553 is configured to receive the outputs of the current compensator 552, and convert the outputs of the current compensator 552 into the conduction control signals CCS!, CCS2 and CCS, respectively, and the impedance control signals ICS, ICS2 and ICS3. . The driving buffer 554 is configured to receive the conduction control signals CCS!, CCS2, and CCS; and output the respective conduction control signals after buffering the above-mentioned conduction control signals. As in the embodiment shown in FIG. 2, the above-mentioned driving buffer 554 is also used for signal buffering and signal amplification of the conduction control signals CCSi, CCS2 and CCS3 outputted by the impedance controller 553, respectively, for 17 years EJ. The user can still choose whether to use the drive buffer 554 in the control unit 550 according to actual needs. The current adjustment unit group 540 includes three current adjustment units '541, 542, and 543, respectively, and the design structure of each current adjustment unit is the same as the current adjustment unit 220 shown in FIG. 2, so the current is not described again. The internal design and mode of operation of the adjustment units 541, 542, and 543. The current adjustment unit 541 is configured to detect the current Ι of the illuminating element string 510, thereby generating the feedback signal FS!′ and receiving the conduction control signal ccs output by the control unit 550 and the impedance control signal ICSi to adjust the illuminating element string 510. The impedance value between the ground voltage GND and the ground. Similarly, the current adjustment early element 542 is used to measure the current 12 of the light-emitting element string 520, thereby generating the feedback signal FS2, and receiving the conduction control signal CCS2 and the impedance control signal icS2 outputted by the control unit 55 to adjust the illumination. The impedance value between the component string 520 and the ground voltage GND. The current adjustment unit 543 is configured to detect the current &amp; amp of the illuminating element string 530, thereby generating a feedback signal FS?, and receiving the conduction control signal CCS3 and the impedance control signal ICS3 output by the control unit 550 to adjust the illuminating element string. The impedance value between 53〇 and the ground voltage GND. In this way, the currents h, I:, and I3 of the light-emitting element strings 51A, 52A, and 530 can be separately controlled to achieve the purpose of adjusting the brightness of the above-described light-emitting element string, and can further be made The luminances of the light-emitting element strings 510, 52A, and 53 are uniform. However, the above current control device i is not limited to adjusting the current of the three light-emitting element strings, cooked 1332138 I (four) month • correction replacement page _ yy «4-29---1 This artist can follow the light The number of current adjustment units in the current adjustment unit 540 is adjusted by the number of component strings, and the error amplifier 55, the current compensator 552, the impedance controller, and the input and output terminals of the drive buffer 554 are adjusted correspondingly. number. . It is worth mentioning that although in the above embodiments, the internal circuit of the current adjustment unit has been drawn out of a possible type, those skilled in the art should be aware that the manufacturers do not design the current adjustment unit. As such, the application of the invention is not limited to this possible type. In other words, as long as the transistor is used, for example, the variable size of the channel size of the M〇s transistor, the bipolar junction transistor, or the insulated gate bipolar transistor (IGBT) is used. And the operation of the transistor in the linear region, and adjusting the channel size of the transistor according to the signal input to the current adjustment unit, thereby controlling the current of the light-emitting element string, is already in line with the spirit of the current adjustment unit of the present invention. In summary, the present invention performs feedback control by using the current of the LED string, and current compensation is performed on the current of the LED string, and then the current compensation result is converted into two kinds of control M〇s. The signal of the impedance value when the transistor is turned on, according to the impedance value when the MOS transistor is turned on, adjusts the current flowing through the LED string, thereby achieving the purpose of adjusting the brightness of the LED string, so the present invention has It has better reliability than the conventional brightness adjustment circuit using the open circuit control method of the current mirror. Although the present invention has been disclosed in the above preferred embodiments, it is not intended to limit the present invention, and those skilled in the art will not depart from the spirit of the invention.

99-4-29 1332138 and the scope of the invention, the scope of protection of the invention is defined by the scope of the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a conventional brightness adjustment circuit. 2 is a current control device in accordance with an embodiment of the present invention. Figure 3 is a partial circuit diagram of Figure 2. 4 is a characteristic diagram of a MOS transistor. Figure 5 is a current control device in accordance with another embodiment of the present invention. [Description of main component symbols] 101: Dual-carrier junction transistors 102, 103: Current mirror 104: Light-emitting diode strings 210, 510, 520, 530: Light-emitting element strings 211, 212 to N: Light-emitting diode 220 541, 542, 543: current adjustment unit 221: MOS transistor 222: variable impedance device 223: feedback unit 224, 228: resistor 225, 226: capacitor 227: diode 230, 550: control unit 231, 551 : Error Amplifiers 232, 552: Current Compensator 1332138

99-4-29 233, 553: Impedance controller 234, 554: Drive buffer 540: Current adjustment unit group CS: Comparison result CCS: On control signal Cgd, cgs: Capacitance value FS: Feedback signal GND: Ground voltage I , I!, I2, I3, Ic, Iml, Im2, In: Current ICS: Impedance control signals ICgd, Ig: Current value Rg, Rgd: Resistance value

Vds, Vg, Vplt, Viedl, Vied2~ViedN: voltage value VLED: power supply voltage Vin: input signal Vref: reference signal 21

Claims (1)

1332138 Revision 99-4-29 X. Patent application scope: 1. A current control device adapted to control a current of a string of light-emitting elements, wherein one end of the string of light-emitting elements is electrically connected to a first potential, the current control The device includes: a current adjustment unit electrically connected between the other end of the light-emitting element string and a second potential for detecting a current of the light-emitting element string, thereby generating a feedback signal, and according to a conduction a control signal and an impedance control signal to control an impedance value between the light-emitting element string and the second potential, thereby controlling a current of the light-emitting element string; and a control unit electrically connected to the current adjustment unit for receiving And comparing the value of a reference signal and the feedback signal to generate a comparison result, and performing current compensation on the comparison result, and converting the comparison result after completing the current compensation into the conduction control signal and the impedance control signal. The current control device of claim 1, wherein the control unit comprises: an error amplifier electrically connected to the current adjustment unit for receiving and comparing the reference signal and the feedback signal a value, according to which the comparison result is generated, a current compensator is electrically connected to the error amplifier for receiving the comparison result, and is rotated after the comparison result is current-compensated; and an impedance controller, The current is connected to the current compensator for receiving the output of the current compensator, and the turn-on control signal of the current compensator and the impedance control signal. The current control device of claim 2, wherein the control unit further comprises a driving buffer H, electrically connected to the impedance control (4), for Receiving the conduction control number, the county will _ magnify the fresh (four) signal and output it. 4. The current control device according to claim 1, wherein the current adjustment unit comprises: An MOS transistor, wherein the M〇s transistor is connected to the other end of the string of light-emitting elements; a variable impedance device electrically connected to the control unit and the M〇s The gate of the crystal is used to transmit the conduction control signal to the M〇s transistor, and the resistance of the variable impedance device is adjusted according to the lion impedance control signal to make the M〇s transistor Changing the conduction state according to the conduction control number and the resistance value of the variable impedance device, thereby adjusting the impedance value when the MOS transistor is turned on; The repairing unit is electrically connected to the MOS, and between the other source/drain of the crystal and the second potential, for detecting the current of the string of the illuminating element, and generating the returning credit accordingly number. | Setting, wherein the electro-crystal gymnastics 5. The current control device as described in claim 4 of the patent scope is as follows: the MOS transistor is an nm 〇s transistor, and the nm 〇s is in a linear region. 6. The current control device according to claim 5, wherein the current adjustment unit further comprises: , 23 1332138 99-4-29 琢 the first resistor is electrically connected to the other end of the string of the illuminating element and the MOS And a first capacitor electrically connected between the gate of the first resistive disc and the MOS transistor. Spears I I. 7. The current adjustment unit further includes: , a dry second capacitor, the second capacitor is electrically connected to the gate of the M〇s and the first Between the two potentials. Basket 8. If you apply for the current control position as described in item 7, the feedback unit includes a first-thunder resistance, and the weft is - ^ a ^ H. The first-resistance is electrically connected to the MOS device. Another source/drain of the body is between the second potential. 9. The current control is as described in claim 8 of the patent scope. The first potential is a power supply voltage. 10. The current control device of claim 9, wherein the second potential is a ground voltage. η. The current control unit of claim 4, wherein the current adjustment unit further comprises: - a pole body, wherein the anode of the diode is electrically connected to the gate of the M〇s transistor, the second The cathode of the polar body is electrically connected to the conduction control signal. 12. The current control device as claimed in claim 3, wherein the light-emitting element string is composed of a plurality of light-emitting diodes. 13. The current control device is adapted to control a plurality of overcurrents, wherein the light-emitting element strings are connected at their ends to a potential, and the current control device comprises: 24 1332138 ^—--99-4-29 A current adjustment unit group is electrically connected between the other end of the string of light-emitting elements and a second potential for detecting the current of each string of light-emitting elements, thereby generating a plurality of feedback signals 'the current adjustment unit group also receives a plurality of conduction control signals and a plurality of impedance control signals, and controls the light-emitting elements according to one of the plurality of conduction control signals and one of the plurality of impedance control signals And an impedance value between the string and the second potential, thereby controlling a current flowing through the string of light emitting elements; and a control unit is electrically connected to the current adjusting unit group for receiving a reference signal and the The signal is fed back, and the value of each feedback signal and the reference signal is compared to generate a plurality of comparison results, and each comparison result is current compensated, and the comparison results after the current compensation is completed are converted into the Turning on the control signal and the impedance control signals. The current control device of claim 13, wherein the control unit comprises: an error amplifier electrically connected to the current adjustment unit group for receiving the reference signal and the feedback signals, and Comparing each feedback signal with the value of the reference signal to generate the comparison results; a current compensator electrically connected to the error amplifier for receiving the comparison results and making currents for each comparison result And respectively outputting; and an impedance controller electrically connected to the current compensator for receiving the outputs of the current compensator, and converting the outputs of the current compensator into the conduction control signals And the impedance control signals. 25 1332138 fft·,月1曰修99-4-29 15. The current control device according to claim 14, wherein the control unit further comprises: a drive buffer electrically connected to the impedance The controller is configured to receive the conduction control &gt; ^ numbers, and respectively output the buffering and amplifying the conduction control signals. 16. The current control device of claim 13, wherein the current adjustment unit group comprises a plurality of electrical integer units, and each current adjustment unit comprises: a MOS transistor 'the M〇s transistor One of the source/non-polarity is electrically connected to the other end of one of the light-emitting element strings; a variable impedance device electrically connected between the control unit and the M〇s transistor to transmit the One of the conduction control signals is connected to the gate of the MOS transistor, and dynamically adjusts the resistance value of the variable impedance device according to one of the impedance control signals, so that the M〇s transistor is controlled according to the conduction The signal and the resistance value of the variable impedance device change the conduction state 'and then the expansion; 5 the impedance value when the transistor is turned on; and a feedback unit, electrically connected to another source of the MOS transistor Between the pole and the second potential, the current of one of the strings of the light-emitting elements is detected, and one of the feedback signals is generated accordingly. 17. The current control device of claim 16, wherein the MOS transistor is an NM〇s transistor, and the NM〇s transistor operates in a linear region. 26 1332138 曰Revision and Replacement Page-99-4-29- 18 · The current control device according to the πth item of the patent application, wherein the current adjustment unit further comprises: · · ^ m the first-resistance is electrically connected to The other end of one of the light-emitting element strings is between the gate of the PCT transistor; and the --capacitor 'the first capacitor is electrically connected between the gates of the MOS transistor. 19. The current control unit of claim 18, wherein the current adjustment unit further comprises: /, a second capacitor 'the second capacitor electrically connected to the gate of the M〇s electric and the Between the second potentials. 20. The electric mi unit according to claim 19, wherein the second resistor is electrically connected to the other source/drain of the 〇s faa body and the second potential. The current control device of claim 20, wherein the first potential is a power supply voltage. /, the m is a current-m2. The current control device of item 1, wherein the current adjustment 2^Bracket =: The current control device of item 16 is 27 1332138 99*4·29 impedance value between the LEDS and the second voltage, and then to control the current of LEDS. The CU is used to compare a reference signal With the FS to generate a result. According to above mentioned result, the CU performs a current compensation, after that transforms to the CCS and the ICS. VII. Designated representative map: (1) The representative representative map of the case is: Figure (2) (2) A brief description of the component symbols of the representative diagram: 210: light-emitting element string 211, 212 to N: light-emitting diode 220: current adjustment unit 221: MOS transistor 222: variable impedance device 223: feedback unit 224 228: Resistor 225, 226: Capacitor 227: Diode 230: Control unit 231: Error amplifier 232: Current compensator 233: Impedance controller 234: Drive buffer CCS: Control signal 1332138 99-4-29 CS : Comparison result FS : Feedback signal GND : Ground voltage ICS : Impedance control signal In : Current VLED : Power supply voltage Vref : Reference signal 8. If there is a chemical formula in this case, please reveal the best Chemical formula showing the characteristics of the invention: none