TW201143516A

TW201143516A - Driving circuit for single-string light-emitting diode (LED) lamp

Info

Publication number: TW201143516A
Application number: TW99116760A
Authority: TW
Inventors: Zuo-Shang Yu; Tsung-Yen Lee
Original assignee: Tpv Electronics Fujian Co Ltd
Priority date: 2010-05-26
Filing date: 2010-05-26
Publication date: 2011-12-01
Also published as: TWI423728B

Abstract

A driving circuit for a single-string light-emitting diode (LED) lamp includes a push-pull converter. The push-pull converter boosts an input low DC voltage of 12-19 volts to a high DC voltage of up to 200 volts for providing power to the single-string LED lamp. The driving circuit controls lamp current of the single-string LED lamp by means of constant current and modulates brightness of the single-string LED lamp by means of pulse-width modulation (PWM) dimming. In addition, the single-string LED lamp provides the standardization design for connectors of the driving circuit used to connect to the single-string LED lamp, so that the driving circuit has better common-use characteristic. Moreover, the driving circuit does not need a current balance circuit, and just needs a cheaper and general purpose integrated circuit to control the push-pull converter to reduce design cost of the driving circuit.

Description

201143516 六、發明說明：【發明所屬之技術領域】本發明是有關於-種發光二極體(Light一Emitting Di〇de，簡稱 LED)的驅動電路，且特別是有關於-種單串㈣燈管的驅動電路中單串LED燈管即I^D燈管中所有LED採用全部串聯方式耦接。、【先前技術】目前的液晶顯示器（Liquid Crystal Display，簡稱⑽，例如液晶螢幕⑽monitor)、液晶電視⑽TV)、將電腦主機整合在液曰螢幕中的-體機電腦⑽七如PC)等，已經開始使用⑽燈^^ 背光。此LED燈管中的LED通常採用串並聯相結合方式祕，例如Μ 燈管中的LED採用8組並聯’且每-組由1(H固串聯的方式耗接。 LED燈管的驅動電路通過電源轉換器將輸入的低壓直流電壓（如 12-19V)升壓為相對較高的直流電壓(如3㈣QV)以提供⑽燈管工作所需的供電電壓，這個供電電壓由LED燈管每—組⑽串聯個數所決定0 、由於目前這種LED燈管並聯組數較多，例如4組並聯、6組並聯、 8組^聯等’為了讓每—組⑽輸出電流相等，必須採用帶有均流功能的專用積體電路或使職雜的均流電路，使得⑽燈管的驅動電路 =十成本較^另外’目前各個面板廠對㈣燈管的輸出輸入端定義路」十燈管並聯組數也各不相同，使得led燈管的驅動電路4無妹準化且共·較差，造成人力及設計成本上的浪費。【發明内容】 201143516 路’且電路設計可標準化而有更好的共用性。本發明提出-種單串LED燈管的鶴電路，其中單串⑽燈管具有輸入端及輸{±|端。單串燈管的驅動電路至少包括調光控制電路、電流迴授電路、脈寬調變（Pulse-Width Modulation ’簡稱剛）控制電路以及推挽讀鋪，其中調光控㈣路與電流迴授電路串聯搞，於單串LED燈管的輸出端及接地端之間，灌控制電路雛至迴 f端且通過迴授端祕朗光控制f路及錢迴授電路，推挽式轉換器耗接至單串LED燈管的輸入端及PWM控制電路。一調光控制電路接收顺形式的調光信號，調光信號每一週期包括一=啟期間及-關閉期間。在開啟期間，調光控制電路控制單串⑽ 燈I的輸it!端與接地端耦接，錢碰電路檢卿單串㈣燈管的輸出端輪出的燈管電流且據以輸出第一迴授電壓至迴授端，讓控制電 ^在ί收到第一迴授電壓時輸出相位差⑽度的兩PWM信號，推挽式、古換，在接收到PWM信號時據以將輸入的第一直流電壓升壓為第二直以輸出至單串LED燈管的輸人端。在關閉期間，調光控制電路，制早串LED燈管的輸出端與接地端_且輸出第二迴授電壓至迴授 ^ ’電流迴授電路未檢測到燈管電流而停止輸出第一迴授電壓，· ^電路在接收到第二迴授雜時停止輸出簡信號，推挽式轉換器接收到PWM信號時停止轉換而不再輸出第二直流電壓。本發明單串LED燈管的驅誠路因採轉挽式轉換㈣可將輸入如12V 19V的低壓/第一直流電壓升壓為2〇〇v以上的高壓/第二直流供單串LED燈f卫作所㈣供電輕，並制定電流方式控^ LED燈管的燈管電流及採用顺調光方式進行單串⑽燈管的節’·另外，本發明因採用單串LED燈管，其與現有的冷陰極螢二管（Cold Cathode Fluorescent Lamp，簡稱 CCFL)具有相同的輸輸入端定義’用於接收高麼/第二直流電麗的輸入端及用於輸出燈管 201143516 電流提供迴授控制的輸出端，使得驅動電路上在與科·燈管輕接.，的連接器設計可標準化而有更好的朗性，且因不需使_流電路而只需採用廉價的通用積體電路來控制推挽式轉換器，使得驅動電路設計成本較低。為讓本發明之上述和其他目的、特徵和優點能更明顯易懂，下文特舉較佳實施例，並配合所附圖式，作詳細說明如下。【實施方式】圖1為本發明的單串led燈管的驅動電路的一實施例電路方塊圖。請參見圖1 ’單串LED燈管4由多個led DL1〜DLn所組成，這些钃 LED DL1〜DLn採用全部串聯方式墟，即 DLi的陰極端減至 DL(^+1)的陽極，’ i為卜⑹）中任一正整數，而leddli的陽極端為單串LED燈管4的輸入端41，LED DLn的陰極端為單串LED燈管4 的輸出端42。單串LED燈管4的驅動電路1包括推挽式轉換器u、調光控制電路12、電流迴授電路13、剛控制電路14、關控制電路 15以及過壓保護電路16。調光控制電路12與電流迴授電路13串聯耦接於單串LED燈管4的輸出端42及接地端18之間，pwm控制電路14 耦接至迴授端17且通過迴授端17耦接至調光控制電路12及電流迴授電路13，推挽式轉換器11輕接至單串LED燈管4的輸入端41及卩而· 控制電路14，開關控制電路15搞接至PWM控制電路14，過屢保護電路16耦接至單串LED燈管4的輸入端41及PWM控制電路14。調光控制電路12接收PWM形式的調光信號dim，調光信號DIM每「週期T包括一開啟期間Ton及一關閉期間T〇ff (在後面的圖5會有進一步敘述）。在開啟期間Ton ’調光控制電路12控制單串LED燈管4 的輸出端42與接地端18耦接，電流迴授電路13檢測到單串LED燈管 4的輸出端42輸出的燈管電流Hamp且據以輸出第一迴授電壓Vfbl 6 201143516 至迴授端Π，PWM控制電路14在接收到第—迴授電壓刪時輸位差180度的兩PWM信號醒和·，推出 =_ * _時據以將輸入的第—直流電壓化升壓為^直^ if 乂輸出至單串LED燈管4的輪入端4卜在關閉期間Toff，路12控制單串L黯管4的輪出端42與接地端18斷開，迴授電壓Vfb2至迴授端17，電流迴授電路13未__ B電^ Ila即而停止輸出第一迴授電壓VfM，觸控制電路Μ在接收到第-iS授電壓Vfb2時停止輸出pwm信號贿和贈，減式轉換器11在未接收到PWM信號酬1和PWM2時停止轉換而不再輸出第二直流電壓Vout。一另外’開關控制電路15接收開關信號〇N/〇FF據〇_控制PWM控制電路15是否工作。過壓保護電路16在^= 電廢Vout大於閾值電壓Vref2時控制pwM控制電路14停止輸出觸信號PWM1和PWM2 (在後面的圖6會有進一步敘述）。201143516 VI. Description of the Invention: [Technical Field] The present invention relates to a driving circuit of a Light Emitting Diode (LED), and in particular to a single-string (four) lamp In the driving circuit of the tube, all the LEDs in the single string LED tube, that is, the I^D tube, are all coupled in series. [Prior Art] The current liquid crystal display (Liquid Crystal Display, referred to as (10), such as LCD screen (10) monitor), LCD TV (10) TV), the computer host integrated in the liquid screen - body computer (10) seven such as PC), etc., Start using (10) light ^^ backlight. The LEDs in this LED tube are usually combined in series and parallel. For example, the LEDs in the 灯 tube are connected in parallel with 8 groups and each group is consumed by 1 (H solid series connection. The driving circuit of the LED tube passes The power converter boosts the input low-voltage DC voltage (such as 12-19V) to a relatively high DC voltage (such as 3 (four) QV) to provide (10) the supply voltage required for lamp operation. This supply voltage is controlled by the LED tube. (10) The number of series is determined by 0. Since there are many parallel groups of LED tubes, for example, 4 sets of parallel, 6 sets of parallel, 8 sets of ^, etc. 'In order to make each group (10) output current equal, it must be adopted The dedicated integrated circuit of the current sharing function or the current sharing circuit of the current miscellaneous circuit makes the driving circuit of the (10) lamp tube = ten cost compared with the other 'currently each panel factory defines the way to the output input end of the (four) lamp tube" The number of groups is also different, so that the driving circuit 4 of the LED tube has no sister and is poor, resulting in waste of manpower and design cost. [Summary] 201143516 Road 'and circuit design can be standardized and better Sharing. The present invention proposes a single string The LED circuit of the LED tube, wherein the single string (10) tube has an input end and a transmission {±| terminal. The driving circuit of the single string tube includes at least a dimming control circuit, a current feedback circuit, and a pulse width modulation (Pulse-Width). Modulation 'abbreviation just】 control circuit and push-pull reading shop, in which the dimming control (four) way and the current feedback circuit are connected in series, between the output end of the single-string LED tube and the ground end, the control circuit is cut to the f-end And through the feedback end secret light control f road and money feedback circuit, the push-pull converter is consumed to the input end of the single string LED tube and the PWM control circuit. A dimming control circuit receives the dimming signal of the cis form Each period of the dimming signal includes a = start period and a close period. During the turn-on period, the dimming control circuit controls the single-string (10) lamp I's input it! end is coupled to the ground end, and the money touches the circuit to check the single string (4) The lamp current outputted from the output end of the lamp tube and according to the output of the first feedback voltage to the feedback end, the control circuit outputs two PWM signals of phase difference (10) degrees when the first feedback voltage is received, Pull-type, ancient change, according to the input of the first DC when receiving the PWM signal The voltage boost is second straight to output to the input end of the single string LED tube. During the off period, the dimming control circuit prepares the output end of the LED tube and the ground terminal _ and outputs the second feedback voltage to Feedback ^ 'The current feedback circuit does not detect the lamp current and stops outputting the first feedback voltage. · ^ The circuit stops outputting the simple signal when receiving the second return, and the push-pull converter receives the PWM signal. The conversion is stopped and the second DC voltage is no longer output. The driving circuit of the single-string LED lamp of the present invention can be boosted to a voltage of 2 〇〇v or higher by inputting a low voltage/first DC voltage of 12V 19V. The high voltage / the second DC for a single string of LED lights, the power supply is light, and the current mode is controlled. The tube current of the LED tube and the section of the single string (10) tube are used in the shun dimming mode. The invention adopts a single string LED tube, which has the same input and output definition as the existing Cold Cathode Fluorescent Lamp (CCFL), and is used for receiving the input of the high/second DC current and For output lamp 201143516 current provides feedback control At the end, the driver circuit is lightly connected to the light tube. The connector design can be standardized and has better singularity, and only needs to use a cheap general-purpose integrated circuit to control the _current circuit. Push-pull converters make drive circuit design less expensive. The above and other objects, features and advantages of the present invention will become more <RTIgt; [Embodiment] FIG. 1 is a circuit block diagram showing an embodiment of a driving circuit of a single-string LED lamp of the present invention. Please refer to FIG. 1 'Single string LED tube 4 is composed of a plurality of LEDs DL1 DLDLn, which are all connected in series, that is, the cathode end of DLi is reduced to the anode of DL (^ +1), ' i is any positive integer in (6)), and the anode end of the leddli is the input end 41 of the single string LED tube 4, and the cathode end of the LED DLn is the output end 42 of the single string LED tube 4. The drive circuit 1 of the single-string LED lamp 4 includes a push-pull converter u, a dimming control circuit 12, a current feedback circuit 13, a just control circuit 14, an off control circuit 15, and an overvoltage protection circuit 16. The dimming control circuit 12 is coupled in series with the current feedback circuit 13 between the output terminal 42 of the single-string LED tube 4 and the ground terminal 18. The pwm control circuit 14 is coupled to the feedback terminal 17 and coupled via the feedback terminal 17. Connected to the dimming control circuit 12 and the current feedback circuit 13, the push-pull converter 11 is connected to the input terminal 41 of the single-string LED tube 4 and the control circuit 14, and the switch control circuit 15 is connected to the PWM control. The circuit 14, the over-protection circuit 16 is coupled to the input terminal 41 of the single-string LED tube 4 and the PWM control circuit 14. The dimming control circuit 12 receives the dimming signal dim in the form of PWM. Each period T of the dimming signal DIM includes an on period Ton and a off period T〇ff (described further in FIG. 5 below). The dimming control circuit 12 controls the output end 42 of the single-string LED tube 4 to be coupled to the ground terminal 18, and the current feedback circuit 13 detects the lamp current Hamp outputted from the output terminal 42 of the single-string LED tube 4 and The first feedback voltage Vfbl 6 201143516 is outputted to the feedback terminal Π, and the PWM control circuit 14 wakes up the two PWM signals with a difference of 180 degrees when receiving the first feedback voltage, and pushes out the =_* _ The input first DC voltage is boosted to ^ directly if 乂 output to the wheel end 4 of the single string LED tube 4 during the off period Toff, the path 12 controls the round end 42 of the single string L黯 tube 4 and The ground terminal 18 is disconnected, and the voltage Vfb2 is fed back to the feedback terminal 17. The current feedback circuit 13 stops the output of the first feedback voltage VfM, and the touch control circuit Μ receives the first-iS grant. When the voltage Vfb2 is stopped, the output of the pwm signal is stopped, and the subtraction converter 11 stops switching when the PWM signal 1 and PWM2 are not received. The second DC voltage Vout is further outputted. An additional 'switch control circuit 15 receives the switching signal 〇N/〇FF according to 〇_ controlling whether the PWM control circuit 15 operates. The overvoltage protection circuit 16 is when the voltage waste Vout is greater than the threshold voltage Vref2 The control pwM control circuit 14 stops outputting the touch signals PWM1 and PWM2 (which will be further described later in Fig. 6).

圖2及圖3分別為圖1所示的推挽式轉換器u的第一及第二實施例電路圖。請參見圖2 ’推挽式轉換器21包括兩功率開關（分別由電晶體Q1和二極體DQ1所組成以及由電晶體Q2及二極體_所组成）、變壓器Ή、輸出整流電路（由二極體D1〜D4所組成）以及輸出滤波電路（由電感器L1及電谷器C1所組成）。變壓器τι初級側兩個繞組的一端祕以接收第-直流輕Vin，另-端分_接至兩電晶體Q1和Q2 的汲極端。兩電晶體Q1和Q2的源極端耦接至接地端18，兩電晶體以和Q2的閘極端分別柄接以接收兩相位差度的p觀信號p爾1和 PWM2。兩電晶體Q1和Q2分別由PWM信號pwM1和pwM2控制而交替地導通’使得變壓器T1初級側的兩個繞組之間產生低壓脈衝方波，變壓器T1將初級側低壓脈衝方波以變壓器Ή次級圈數與初級倍數升塵成高|脈衝方波。輸出整流電路將麵器T1輸出的高壓脈衝 201143516 方波整流成高壓脈動直流電壓，此高壓脈動直流電壓最後再通過輸出濾波電路濾成高壓低漣波的第二直流電壓Vout以提供單串LED燈管4 工作所需的供電電壓。請參見圖3，推挽式轉換器31及圖2所示的推挽式轉換器21差異主要在於輸出整流電路。推挽式轉換器21的輸出整流電路是由二極體D1〜D4所組成的橋式整流電路，其中二極體D1和D2用於整流，而二極體D3和D4用於續流。推挽式轉換器31的輸出整流電路是由用於整流的二極體D1和D2所組成’再通過變壓器T1次級側中間抽頭耗接至接地端18提供電流路徑用於續流。圖4為圖1所示的調光控制電路12、電流迴授電路13及pWM控 · 制電路14的一實施例電路圖，圖5為圖4所示的電路的p⑽(調光控制時序圖。請參見圖4及圖5，調光控制電路22包括第一單向導通元件 (由二極體D5所組成）、第一反相電路（由電晶體Q3及電阻器R1〜R4 所組成）、第二反相電路（由電晶體Q4及電阻器R5和胱所組成）以及開關（由電晶體Q5所組成）。第一反相電路接收調光信號dim，並輸出與調光信號DIM反相的反相調光信號DIM1，其中調光信號dim每一週期T包括一開啟期間Ton及一關閉期間Toff。反相調光信號dimi通過第一單向導通元件耦接至迴授端17，以在開啟期間τ〇η停止輸出第籲二迴授電壓Vfb2至迴授端17 ’在關閉期間Toff輸出第二迴授電壓 Vfb2至迴授端17。第二反相電路耦接至第一反相電路，接收反相調光 “號DIM1 ’並輸出與反相s周光k號DIM1反相的同相調光信號mm2。開關與電流迴授電路23串聯耦接於單串le：D燈管4的輸出端42及接地端18之間。開關根據同相調光信號DIM2在開啟期間Torl開啟以控制輸出端42通過電流迴授電路23的電阻器R7耦接至接地端18，在關閉期間Toff關閉以控制輸出端42與接地端18斷開。在開啟期間Ton，調光信號DIM為高準位電壓而使電晶體⑽導 8 201143516 '通，電晶體Q3導通會使反相調光信號DIM1為低準位電壓（電壓為$)，進而使電晶體Q4截止，電晶體Q4截止會使同相調光信號為高準位電壓（電壓為R6/(R5+R6)xVdc2)，進而使電晶體q5導通，電晶體Q5 導通會使開關開啟而控制輸出端42與接地端18耦接，此時單串LED 燈管4的燈管電流Ilamp不為零而會發光（亮），其中Vdc2為直流電壓。在關閉期間Toff ’調光信號DIM為低準位電壓而使電晶體⑽截止，電晶體Q3截止會使反相調光信號DIM1為高準位電壓（電壓為 (R3+R4)/(R2+R3+R4)xVdcl) ’進而使電晶體Q4導通，電晶體q4導通會使同相調光信號DIM2為低準位電壓（電壓為零），進而使電晶體奶 Φ 截止，電晶體Q5截止會使開關關閉而控制輸出端42與接地端18斷開，此時單串LED燈管4的燈管電流I lamp為零而不會發光（暗），其中Vdcl為直流電壓。因此，單串LED燈管4在開啟期間τ〇η亮而在關閉期間Toff暗’當調光信號DIM的頻率在15〇Hz以上時，人眼將因視覺暫留的影響而感覺不到燈管4的亮暗變化，只能感覺到這個變化的平均值’故可以透過調整亮暗的比例（即調整調光信號DIM的責任週期）來達到調整晝面亮度之調光效果’這種調光方式即稱為調光或突發模式(burst mode)調光。 • 另外，反相調光信號DIM1先通過電阻器R3和R4分壓成DIM1，再通過一極體D5搞接至迴授端17。在開啟期間τ〇η ,反相調光信號 DIM1電壓為零，故反相調光信號DIM1，電壓同樣為零，二極體卯截止’因而停止輸出第二迴授電壓Vfb2至迴授端17。在關閉期間Toff，反相調光信號DIM1電壓為（R3+R4)/(R2+R3+R4)xVdcl，故反相調光信號DIM1’電壓為R4/(R2+R3+R4)xVdd ’使二極體D5導通，因而輸出第二迴授電壓Vfb2 (電壓為R4/(R2+R3+R4)xVdcl-Vd5)至迴授端17，其中Vd5為二極體D5導通壓降，且可知電阻器R3和R4用於調整第二迴授電壓Vfb2的迴授量。 9 201143516 方雷包括第二單向導通元件（由二極體d6所組成）以光控制電路22的開關（由電晶體Q5所組成) ^由雷⑽燈管4的輸出端42及接地端18之間。電流檢測 =(由電阻器R7所組成)檢測單串⑽燈管4的燈管電流！ia即且據以 =出檢測電壓Vr7，檢測電壓Μ通·二單㈣通元件祕至迴授端17，以在開啟期間Ton輸出第一迴授·咖至迴授端17，在關醜間Toff停止輸出第一迴授電壓至迴授端1?。電流迴授電路 23還包括電阻器R8和R9以及電容器C2，其中電阻器⑽和即用於分壓以調整第-迴授電壓咖的迴授量，且通常所選用的電阻器狀和 R9的電阻值必須遠大於電流檢測器R7的電阻值，以確保燈管電流 I lamp幾乎全部往電流檢測器R7流過，電容器C2用於滤除高頻雜訊。在開啟期間Ton，電晶體Q5導通，燈管電流η_不為零而在電流檢測電阻器R7上產生壓降’這個壓降即是與燈管電流1 _大小相，的檢測電壓Vr7 ’使一極體D6導通，因而檢測電壓vr7先通過電阻器R8和R9分壓成具有適當準位的第一迴授電壓Vfbl (電壓為 (Vr7-Vd6)xR9/(R8+R9))再輸出至迴授端π，其中為二極體D6的導通壓降。在關閉期間Toff，燈管電流Hamp為零而使檢測電壓Vr7 為零，使二極體D6截止，因而停止輸出第一迴授電-Vfbl至迴授端 17。所以，迴授端π的電壓，即迴授端信號FB，在開啟期間τ〇η等於第一迴授電壓Vfbl (電壓為(Vr7-Vd6)xR9/(R8+R9)),在關閉期間 Toff等於第二迴授電壓Vfb2 (電壓為R4/⑽+R3+R4)xVdcl-Vd5)，在本例中第一迴授電壓Vfbl小於第二迴授電壓Vfb2。 PWM控制電路24包括PWM控制器ΙΠ、輸出驅動電路241以及電阻電容補償電路（由電阻器R10及電容器C3所組成）。PWM控制器U1例如是TL494積體電路，其第1至第3接腳分別為誤差放大器eai的非 201143516 »^ 反相輸入端、反相輸入端及輸出端’其第9及第1〇接腳分別用於輸出 PWM信號PWM1和PWM2。PWM控制器m包括誤差放大器EM。誤差放大器EA1具有兩輸入端（即非反相輸入端和反相輸入端）及輸出端，其中 -輸入端（即非反相輸人端)雛至迴授端17，另—輸人端（即反相輸入端）接收參考電壓Vrefl。電阻電容補償電路的電阻器R1〇及電容器 C3串聯輕接於誤差放大器EA1的一輪入端（即反相輸入端）及誤差放大器EA1的輸出端之間’使誤差放大器謝為負迴授架構。由於誤差放大H EA1為負迴授架構，兩輸入端有虛短路特性，因此在開啟期間Ton將迫使迴授端信號FB (此時其電壓等於第一迴授電壓Vfbl)等於參考電壓VreH。此時由於燈管電流Ilamp為Vr7/R7且第-迴授電M Vfbl為（Vr7-Vd6)xK9/⑽側）’如此可通過設計參考電壓Vrefl的電壓值及電阻器R7的電阻值來達成設定燈管電流以即的^流值。另外’誤差放大器EA1在開啟期間τ〇η因迴授端17的電壓 FB等於參考電壓Vrefl而控制PWM控制器υΐ輸出PWM信號PWM1和 PWM2，在關閉期間Toff因迴授端π的電壓FB (此時其電壓等於第二迴授電壓Vfb2)大於參考電壓Vref 1而控制PWM控制器U1停止輸出PWM 信號PWM1和PWM2 〇 1 由於PWM控制器U1輸出的PWM信號PWM1和PWM2可能驅動能力不足而無法驅動圖2或圖3所示的推挽式轉換器21或31中的兩電晶體 Q1和Q2，因此PWM控制器U1輸出的PWM信號PWM1和PWM2通常還會通過輸出驅動電路241來加強其驅動能力。圖6為圖1所示的開關控制電路15、過壓保護電路16&pwM控制電路14的第一貫施例電路圖。請參見圖6，p觀控制電路％的酬控制器U1例如是TL494積體電路而内建有兩個誤差放大器EA1和 EA2’其第16及第15接腳分別為誤差放大器EA2的非反相輸入端及反相輸入端，其第12接腳用於接收提供PWM控制器U1工作所需的供電 201143516 電壓。PWM控制器U1的誤差放大器EAI用於如圖4及圖5所示的燈管電流Ilamp迴授控制及PWM調光，誤差放大器M2用於過壓保護。開，控制電路25包括電晶體q6和Q?。當開關錢QN/QFF為高，位電壓而表相啟時，電晶體如導通，使電晶體Q7導通直流電可傳送到pwm控制器μ提供其工作所需的供電電壓。當開關域0N/0FF為低準位電壓而表示關閉時，電晶體⑽截止使電晶體阶截止，直流電壓Vdc3無法傳送到PWM控制器m，pWM控制器讥停止工作，故PWM控制電路24停止工作。開關控制電路25可用來控制單串LED燈管4的驅動電路i是否要工作，在待機省電等模式下關閉驅動電路1，使得LED燈管4停止工作。。過壓保護電路26包括電阻n R11和R12以及電容器C4，其中電阻器R11的-：^耗接至單串Led燈管4的輸入端41以接收第二直流電壓=out，電阻器RU和R12用於分壓以調整第二直流電壓的取樣量’電容器G4用㈣除高雜訊干擾。過壓保護電路26將取樣的第-直流電壓Vout輸出到應控制器叫的誤差放大器EA2以便與閾值電壓Vref2一進行比較。當取樣的第二直流電壓㈣小於間值^壓 Vrei2時’表不第二直流電壓v〇ut沒有過壓，因此控制簡控制電路 24正*工作田，取樣的第二直流電壓v〇ut大於閾值電壓vreu時，表示第二直流電壓V0ut有過壓，因此控制酬控制電路⑷亭止輸出 PWM信號PWM1和PWM2。過壓保護電路沈可提供輸入到⑽燈管4的第-直流電壓Vout _在某—安全電壓以内，以防止當單串⑽燈管 4或其驅動電路1出現異常問題時造成第二直流電壓_過高而可能導致LED燈管4或其驅動電路丨燒毀的情況。圖7為圖1所不的過壓保護電路16及酬控制電路^的第知例電路圖。清參見圖7，PWM控制電路34包括酬控制㈣、輸出驅動電路341以及電阻電容補償電路（由電阻器_及電容器所組 12 201143516 成）° PWM控制器U2例如是SG3525積體 EM 1^2 EAf ，其第11及第14接腳分別用於輸出酬信號電電壓。泛差放/Λ腳用於接收提供PWM控制器u2工作所需的供具有兩輸入端（即非反相輸人端和反相輸入⑹ 雨、輪入端（即反相輸入端）耦接至迴授端17，另一輸入 f:非t輸入端)接收參考電屢Vrefi。電阻電容補償電路的電阻 Μ容器Ο串聯触於誤差放大器EA1的一輸入端（即反相輸入知々放大器EA1的輸出端之間，使誤差放大器EM為負迴授架構而爾控制器U2輸出的簡信號簡1和PWM2通過輸出驅動電路 341來加強其驅動能力，以驅動圖2或圖3所示的推挽式轉換器21或 31中的兩電晶體卯和收。由於PWM控制電路34僅有一個誤差放大器，因此過壓保護電路 36除了，括如圖6所示的電阻器RU和R12以及電容器以之外還包括運算放大器0P1及電晶體q心過壓保護電路36將通過電阻器R11 和R12取樣的第二直流電壓v〇ut輸出到運算放大器〇ρι以便與閾值電壓Vref2進行比較。當取樣的第二直流電壓v〇ut小於閾值電壓什沿時’表不第二直流電壓v〇ut沒有過壓，運算放大器〇pi控制電晶體2 and 3 are circuit diagrams of the first and second embodiments of the push-pull converter u shown in Fig. 1, respectively. Please refer to FIG. 2 'Push-pull converter 21 includes two power switches (composed of transistor Q1 and diode DQ1 and composed of transistor Q2 and diode _, respectively), transformer Ή, output rectifier circuit (by The diodes D1 to D4 are composed of an output filter circuit (composed of the inductor L1 and the electric grid C1). One end of the two windings on the primary side of the transformer τ1 receives the first-direct current light Vin, and the other end is connected to the 汲 terminal of the two transistors Q1 and Q2. The source terminals of the two transistors Q1 and Q2 are coupled to the ground terminal 18. The two transistors are respectively coupled to the gate terminals of Q2 to receive the two phase difference p signals p er 1 and PWM 2 . The two transistors Q1 and Q2 are alternately turned on by the PWM signals pwM1 and pwM2, respectively, so that a low-voltage pulse square wave is generated between the two windings on the primary side of the transformer T1, and the transformer T1 uses the primary-side low-voltage pulse square wave as a transformer. The number of turns is higher than the primary multiple. The pulse square wave. The output rectifier circuit rectifies the high voltage pulse 201143516 square wave outputted by the surface device T1 into a high voltage pulsating DC voltage, and finally the high voltage pulsating DC voltage is finally filtered by the output filter circuit into a high voltage low chopping second DC voltage Vout to provide a single string LED lamp. The supply voltage required for the operation of tube 4. Referring to Fig. 3, the push-pull converter 31 and the push-pull converter 21 shown in Fig. 2 differ mainly in the output rectifier circuit. The output rectifying circuit of the push-pull converter 21 is a bridge rectifying circuit composed of diodes D1 to D4, in which diodes D1 and D2 are used for rectification, and diodes D3 and D4 are used for freewheeling. The output rectification circuit of the push-pull converter 31 is composed of diodes D1 and D2 for rectification and is then supplied to ground terminal 18 through the secondary side of the transformer T1 to provide a current path for freewheeling. 4 is a circuit diagram of an embodiment of the dimming control circuit 12, the current feedback circuit 13, and the pWM control circuit 14 shown in FIG. 1, and FIG. 5 is a p(10) (dimming control timing chart) of the circuit shown in FIG. Referring to FIG. 4 and FIG. 5, the dimming control circuit 22 includes a first unidirectional conduction component (composed of the diode D5) and a first inverter circuit (composed of the transistor Q3 and the resistors R1 RR4). a second inverter circuit (composed of transistor Q4 and resistor R5 and cyst) and a switch (composed of transistor Q5). The first inverter circuit receives the dimming signal dim and outputs the output to the dimming signal DIM The inverting dimming signal DIM1, wherein the dimming signal dim includes an on period Ton and a off period Toff. The inverting dimming signal dimi is coupled to the feedback terminal 17 through the first one-way conducting element to During the turn-on period, τ〇η stops outputting the second feedback voltage Vfb2 to the feedback terminal 17' during the off period Toff, and outputs the second feedback voltage Vfb2 to the feedback terminal 17. The second inverter circuit is coupled to the first inversion phase. The circuit receives the inverting dimming "No. DIM1 ' and outputs the in phase with the inverted phase s of the inverted light s KIM DIM1 The optical signal is connected to the current feedback circuit 23 in series between the output end 42 of the single-string le:D lamp tube 4 and the ground terminal 18. The switch is turned on according to the in-phase dimming signal DIM2 during the opening period to control the output end. The resistor R7 of the current feedback circuit 23 is coupled to the ground terminal 18, and Toff is turned off during the off period to control the output terminal 42 to be disconnected from the ground terminal 18. During the on period Ton, the dimming signal DIM is at a high level voltage. Let the transistor (10) lead 8 201143516 'pass, the transistor Q3 turns on, the inverted dimming signal DIM1 is low level voltage (voltage is $), and then the transistor Q4 is turned off, the transistor Q4 is cut off to make the in-phase dimming signal The high-level voltage (voltage is R6/(R5+R6)xVdc2), and then the transistor q5 is turned on, the transistor Q5 is turned on to make the switch open and the control output 42 is coupled to the ground terminal 18, at this time, the single-string LED The lamp current Ilamp of the lamp tube 4 is not zero and will emit light (bright), wherein Vdc2 is a DC voltage. During the off period, the Toff 'dimming signal DIM is a low level voltage and the transistor (10) is turned off, and the transistor Q3 is turned off. Making the inverting dimming signal DIM1 a high level voltage (voltage is (R3+R4)/(R2+R3+R4)xVdcl) 'In turn, the transistor Q4 is turned on, and the transistor q4 is turned on to make the in-phase dimming signal DIM2 a low level voltage (voltage is zero), thereby making the transistor milk Φ cutoff, the transistor Q5 is cut off, the switch is closed and the control output 42 is disconnected from the ground terminal 18. At this time, the lamp current I lamp of the single string LED tube 4 is zero without illuminating (dark), wherein Vdcl is DC voltage. Therefore, the single-string LED tube 4 is bright during the turn-on period and Toff is dark during the turn-off period. When the frequency of the dimming signal DIM is above 15 Hz, the human eye will feel the effect of persistence of vision. If the brightness of the lamp 4 is not changed, the average value of the change can only be felt. Therefore, the dimming effect of adjusting the brightness of the kneading surface can be achieved by adjusting the ratio of light and dark (ie, adjusting the duty cycle of the dimming signal DIM). This dimming method is called dimming or burst mode dimming. • In addition, the inverting dimming signal DIM1 is first divided into DIM1 through resistors R3 and R4, and then connected to the feedback terminal 17 through a pole D5. During the turn-on period τ〇η, the voltage of the inverted dimming signal DIM1 is zero, so the inverted dimming signal DIM1, the voltage is also zero, and the diode turns off, thus stopping outputting the second feedback voltage Vfb2 to the feedback terminal 17 . During the off period Toff, the voltage of the inverting dimming signal DIM1 is (R3+R4)/(R2+R3+R4)xVdcl, so the voltage of the inverted dimming signal DIM1' is R4/(R2+R3+R4)xVdd' The diode D5 is turned on, thereby outputting a second feedback voltage Vfb2 (voltage is R4/(R2+R3+R4)xVdcl-Vd5) to the feedback terminal 17, where Vd5 is the diode D5 conduction voltage drop, and the resistance is known The R3 and R4 are used to adjust the feedback amount of the second feedback voltage Vfb2. 9 201143516 The square mine includes a second unidirectional conduction element (consisting of diode d6) with a switch of light control circuit 22 (consisting of transistor Q5) ^ output terminal 42 and ground terminal 18 of ray (10) lamp tube 4 between. Current Detection = (consisting of resistor R7) Detects the lamp current of a single string (10) of lamps 4! Ia, and according to the = detection voltage Vr7, the detection voltage ·通 · two single (four) pass element secret to the feedback end 17, in order to open the first feedback · coffee to the feedback end 17 during the opening period, in the ugly Toff stops outputting the first feedback voltage to the feedback terminal 1?. The current feedback circuit 23 further includes resistors R8 and R9 and a capacitor C2, wherein the resistor (10) and the feedback amount used to divide the voltage to adjust the first feedback voltage are generally selected for the resistor shape and the R9 The resistance value must be much larger than the resistance value of the current detector R7 to ensure that the lamp current Ilamp flows almost all through the current detector R7, and the capacitor C2 is used to filter out high frequency noise. During the on period Ton, the transistor Q5 is turned on, the lamp current η_ is not zero, and a voltage drop is generated on the current detecting resistor R7. This voltage drop is the detection voltage Vr7 ' with the lamp current 1 _ magnitude. The one-pole body D6 is turned on, so that the detection voltage vr7 is first divided by the resistors R8 and R9 into a first feedback voltage Vfbl (voltage is (Vr7-Vd6)xR9/(R8+R9)) with an appropriate level and then output to The feedback terminal π, which is the conduction voltage drop of the diode D6. During the off period Toff, the lamp current Hamp is zero and the detection voltage Vr7 is zero, causing the diode D6 to be turned off, thereby stopping the output of the first feedback power -Vfbl to the feedback terminal 17. Therefore, the voltage of the feedback terminal π, that is, the feedback terminal signal FB, is equal to the first feedback voltage Vfbl during the turn-on period (voltage is (Vr7-Vd6)xR9/(R8+R9)), during the off period Toff It is equal to the second feedback voltage Vfb2 (voltage is R4/(10)+R3+R4)xVdcl-Vd5), and in this example, the first feedback voltage Vfbl is smaller than the second feedback voltage Vfb2. The PWM control circuit 24 includes a PWM controller ΙΠ, an output drive circuit 241, and a resistor-capacitor compensation circuit (composed of a resistor R10 and a capacitor C3). The PWM controller U1 is, for example, a TL494 integrated circuit, and the first to third pins are respectively the non-201143516 of the error amplifier eai, the inverting input terminal, the inverting input terminal, and the output terminal 'the ninth and the first ones The pins are used to output PWM signals PWM1 and PWM2, respectively. The PWM controller m includes an error amplifier EM. The error amplifier EA1 has two input terminals (ie, a non-inverting input terminal and an inverting input terminal) and an output terminal, wherein the - input terminal (ie, the non-inverting input terminal) is juxtaposed to the feedback terminal 17, and the other input terminal ( That is, the inverting input terminal receives the reference voltage Vref1. The resistor R1〇 and the capacitor C3 of the resistor-capacitor compensation circuit are connected in series between one round-in terminal (ie, the inverting input terminal) of the error amplifier EA1 and the output terminal of the error amplifier EA1, so that the error amplifier is a negative feedback architecture. Since the error amplification H EA1 is a negative feedback architecture, the two inputs have a virtual short-circuit characteristic, so during the turn-on period Ton will force the feedback terminal signal FB (when its voltage is equal to the first feedback voltage Vfbl) equal to the reference voltage VreH. At this time, since the lamp current Ilamp is Vr7/R7 and the first-return power M Vfbl is (Vr7-Vd6)xK9/(10) side), the voltage value of the reference voltage Vref1 and the resistance value of the resistor R7 can be achieved. Set the lamp current to the current value. In addition, the error amplifier EA1 controls the PWM controller to output PWM signals PWM1 and PWM2 during the turn-on period τ〇η because the voltage FB of the feedback terminal 17 is equal to the reference voltage Vref1, and the voltage FB of the feedback terminal π during the off period When the voltage is equal to the second feedback voltage Vfb2) is greater than the reference voltage Vref1, the control PWM controller U1 stops outputting the PWM signals PWM1 and PWM2 〇1. The PWM signals PWM1 and PWM2 output by the PWM controller U1 may not be able to drive because of insufficient driving capability. The two transistors Q1 and Q2 in the push-pull converter 21 or 31 shown in FIG. 2 or FIG. 3, therefore, the PWM signals PWM1 and PWM2 output from the PWM controller U1 are usually also boosted by the output driving circuit 241. . Fig. 6 is a circuit diagram showing a first embodiment of the switch control circuit 15, the overvoltage protection circuit 16 & pwM control circuit 14 shown in Fig. 1. Referring to FIG. 6, the control unit U1 of the control circuit is, for example, a TL494 integrated circuit with two error amplifiers EA1 and EA2' built therein. The 16th and 15th pins are non-inverting of the error amplifier EA2, respectively. The input terminal and the inverting input terminal, the 12th pin is used to receive the power supply 201143516 required to provide the PWM controller U1. The error amplifier EAI of the PWM controller U1 is used for the lamp current Ilamp feedback control and PWM dimming as shown in Figs. 4 and 5, and the error amplifier M2 is used for overvoltage protection. The control circuit 25 includes transistors q6 and Q?. When the switch QN/QFF is high and the bit voltage is turned on, the transistor is turned on, so that the transistor Q7 is turned on and the DC can be transferred to the pwm controller μ to supply the supply voltage required for its operation. When the switch domain 0N/0FF is low level and indicates off, the transistor (10) is turned off to turn off the transistor, the DC voltage Vdc3 cannot be transmitted to the PWM controller m, and the pWM controller stops working, so the PWM control circuit 24 stops. jobs. The switch control circuit 25 can be used to control whether or not the drive circuit i of the single-string LED lamp 4 is to be operated, and the drive circuit 1 is turned off in a standby power-saving mode or the like, so that the LED lamp 4 is stopped. . The overvoltage protection circuit 26 includes resistors n R11 and R12 and a capacitor C4, wherein the -R of the resistor R11 is drained to the input 41 of the single string Led bulb 4 to receive the second DC voltage =out, resistors RU and R12 Used to divide the voltage to adjust the sampling amount of the second DC voltage. Capacitor G4 uses (4) to remove high noise interference. The overvoltage protection circuit 26 outputs the sampled first DC voltage Vout to the error amplifier EA2 called by the controller for comparison with the threshold voltage Vref2. When the sampled second DC voltage (4) is less than the interval value Vrei2, 'the second DC voltage v〇ut is not overvoltage, so the control simple control circuit 24 is working*, and the sampled second DC voltage v〇ut is greater than When the threshold voltage vreu indicates that the second DC voltage V0ut has an overvoltage, the control circuit (4) stops outputting the PWM signals PWM1 and PWM2. The overvoltage protection circuit sink can provide a first DC voltage Vout _ input to the (10) lamp tube 4 within a certain safety voltage to prevent a second DC voltage when an abnormal problem occurs in the single string (10) lamp tube 4 or its driving circuit 1 _ is too high and may cause the LED tube 4 or its driving circuit to burn out. Fig. 7 is a circuit diagram showing a first example of the overvoltage protection circuit 16 and the compensation control circuit of Fig. 1. Referring to FIG. 7, the PWM control circuit 34 includes a compensation control (4), an output drive circuit 341, and a resistor-capacitor compensation circuit (from the resistor_and capacitor group 12 201143516). The PWM controller U2 is, for example, an SG3525 integrated body EM 1^2. EAf, its 11th and 14th pins are used to output the signal voltage. The universal differential / pin is used to receive the PWM controller u2 to work with two inputs (ie non-inverting input and inverting input (6) rain, wheel-in (ie, inverting input) coupling To the feedback terminal 17, another input f: non-t input) receives the reference power Vrefi. The resistor Μ container Ο of the resistor-capacitor compensation circuit is connected in series with an input terminal of the error amplifier EA1 (ie, the output terminal of the inverting input 々 amplifier EA1, so that the error amplifier EM is a negative feedback architecture and the controller U2 outputs The simple signal 1 and PWM2 enhance their driving capability by the output driving circuit 341 to drive the two transistors in the push-pull converter 21 or 31 shown in Fig. 2 or Fig. 3. Since the PWM control circuit 34 only There is an error amplifier, so the overvoltage protection circuit 36 includes, in addition to the resistors RU and R12 and the capacitor shown in FIG. 6, an operational amplifier OP1 and a transistor q-core overvoltage protection circuit 36 which will pass through the resistor R11. And the second DC voltage v〇ut sampled by R12 is output to the operational amplifier 〇ρι for comparison with the threshold voltage Vref2. When the sampled second DC voltage v〇ut is less than the threshold voltage, the second DC voltage v〇 is expressed. Ut no overvoltage, op amp 〇pi control transistor

Q8截止’此時由開關信號ΟΝ/OFF決定是否提供直流電壓Vdc3給PWM 控制器U2來控制pwm控制器U2或PWM控制電路34是否工作。當取樣的第二直流電壓Vout大於閾值電壓Vref2時，表示第二直流電壓Vout 有過壓’運算放大器〇ρι控制電晶體Q8導通，使開關信號〇N/〇FF被拉低為低準位電壓而表示關閉，此時開關信號0N/0FF控制PWM控制電路34停止工作。圖8為本發明的液晶顯示器的一實施例電路方塊圖。請參見圖8，液曰日顯示器5包括交流至直流（Alternating-Current to Direct- 13 201143516 ♦ <Q8 OFF' At this time, whether or not the DC voltage Vdc3 is supplied to the PWM controller U2 is controlled by the switching signal ΟΝ/OFF to control whether the pwm controller U2 or the PWM control circuit 34 operates. When the sampled second DC voltage Vout is greater than the threshold voltage Vref2, it indicates that the second DC voltage Vout has an overvoltage. The operational amplifier 〇ρι controls the transistor Q8 to be turned on, so that the switching signal 〇N/〇FF is pulled low to a low level voltage. On the other hand, the switch is turned off, and the switch signal ON/OFF controls the PWM control circuit 34 to stop operating. Figure 8 is a circuit block diagram of an embodiment of a liquid crystal display of the present invention. Referring to Figure 8, the liquid helium display 5 includes AC to DC (Alternating-Current to Direct- 13 201143516 ♦ <

Current，簡稱AC/DC)轉換器5】、主板控制電路52、面板驅動電路53 j及如圖1所示的單串LED燈管4及其驅動電路1，其中單串LED燈管4作為液晶顯示器3的背光。液晶顯示器5例如是液晶螢幕、液晶電視、將電腦主機整合在液晶螢幕中的一體機電腦等。AC/DC轉換器 5^將輸入的交流電壓Vac轉換成不同準位的直流電壓和以分別提供㈣祕1和主板控制電路52王作所騎供電賴。主板於制電路52内建有直流至直流(DG/DG)轉換器將輸人的直流電壓^ 轉換成直流電壓Vdc5以提供面板驅動電路53工作所需的供電電壓。主板控制電路52輸出_信號⑽麟及調光信號DIM以控制驅動電路1驅動單串LED燈管4，還輸出控制錢LVDS控_板Current, abbreviated as AC/DC converter 5], main board control circuit 52, panel drive circuit 53 j and single string LED tube 4 and its driving circuit 1 as shown in FIG. 1 , wherein single string LED tube 4 is used as liquid crystal The backlight of the display 3. The liquid crystal display 5 is, for example, a liquid crystal screen, a liquid crystal television, an all-in-one computer in which a computer main body is integrated in a liquid crystal screen, and the like. The AC/DC converter 5^ converts the input AC voltage Vac into DC voltages of different levels and provides (4) Secret 1 and the motherboard control circuit 52. A DC-to-DC (DG/DG) converter is built into the main circuit 52 to convert the input DC voltage to a DC voltage Vdc5 to provide the supply voltage required for the panel drive circuit 53 to operate. The mainboard control circuit 52 outputs a signal (10) and a dimming signal DIM to control the driving circuit 1 to drive the single string LED tube 4, and also outputs a control LVDS control board.

驅動面板顯示影像㈣。％㈣W 而所述’本發明單串燈管的驅動電路因採用推挽式轉換器 =將輸入的如12V-19V的低壓/第一直流電壓升壓為贿以上的高坠第一直流電壓以提供單串LED鮮工作所需的供電·，並採電流方式控制單串LED燈管的燈管電流及採用簡 ⑽燈管的亮度調節;另外，本發明因採用單串⑽燈;== 具有侧的輸出輸人端定義，祕接收高壓/第二直流電= ，入&及·輸出燈管電流提供迴授控_輸出端，使得驅動電路上接的連接器設計可標準化而有更好的共同性，且 ==:=價_積體電路來―挽式轉明，施纖露如上，然其並_於限定本發二在不脫離本發明之精神和範_，當可作此【圖式簡單說明】 201143516 圖1為本發明的單串LED燈管的驅動電路的一實施例電路方塊圖。圖2及圖3分別為圖1所示的推挽式轉換器u的第一及第二實施例電路圖。圖4為圖1所示的調光控制電路、電流迴授電路及pWM控制電路的一實施例電路圖。圖5為圖4所示的調光控制電路、電流迴授電路及pWM控制電路的PWM調光控制時序圖。圖6及圖7分別為圖1所示的開關控制電路、過壓保護電路及剛控制電路的第一及第二實施例電路圖。圖8為本發明的液晶顯示器的一實施例電路方塊圖。【主要元件符號說明】The drive panel displays the image (4). %(四)W The driving circuit of the single string lamp of the present invention uses a push-pull converter = boosts the input low voltage/first DC voltage of 12V-19V into a high DC voltage of the bribe above Providing the power supply required for a single string of LED fresh work, and controlling the current of the single-string LED tube by the current mode and adjusting the brightness of the simple (10) tube; in addition, the present invention uses a single string (10) lamp; Side output and input terminal definition, secret receiving high voltage / second direct current =, input & and · output lamp current is provided back to the control _ output, so that the connector design of the drive circuit can be standardized and better Commonality, and ==:=price_integrated circuit to pull-to-turn, apply the fiber as above, but it is not limited to the spirit and scope of the present invention, when it can be used BRIEF DESCRIPTION OF THE DRAWINGS 201143516 FIG. 1 is a circuit block diagram showing an embodiment of a driving circuit of a single string LED lamp of the present invention. 2 and 3 are circuit diagrams of the first and second embodiments of the push-pull converter u shown in Fig. 1, respectively. Fig. 4 is a circuit diagram showing an embodiment of the dimming control circuit, the current feedback circuit, and the pWM control circuit shown in Fig. 1. Fig. 5 is a timing chart of PWM dimming control of the dimming control circuit, the current feedback circuit, and the pWM control circuit shown in Fig. 4. 6 and 7 are circuit diagrams of the first and second embodiments of the switch control circuit, the overvoltage protection circuit, and the just control circuit shown in Fig. 1, respectively. Figure 8 is a circuit block diagram of an embodiment of a liquid crystal display of the present invention. [Main component symbol description]

11、2卜31 :推挽式轉換器 13、23 :電流迴授電路 15、25 :開關控制電路 17 :迴授端 241、341 :輸出驅動電路 41 :輸入端 5:液晶顯示器 52 :主板控制電路 C1〜C4 :電容器 DL1 〜DLn : LED 1 .單串LED燈管的驅動電路 12 ' 22 :調光控制電路 14、24、34:PWM控制電路 16、26、36 :過壓保護電路 18 :接地端 4 :單串LED燈管 42 :輸出端 51 : AC/DC轉換器即：面板驅動電路 D1〜D6、DQ卜DQ2 :二極體 15 201143516 EAl、EA2 :誤差放大器 0P1 :運算放大器 R1〜R12 :電阻器11, 2b 31: Push-pull converter 13, 23: current feedback circuit 15, 25: switch control circuit 17: feedback terminal 241, 341: output drive circuit 41: input terminal 5: liquid crystal display 52: main board control Circuits C1 to C4: Capacitors DL1 to DLn: LEDs 1. Single-string LED lamp drive circuit 12' 22: Dimming control circuits 14, 24, 34: PWM control circuits 16, 26, 36: Overvoltage protection circuit 18: Ground terminal 4: Single string LED tube 42: Output terminal 51: AC/DC converter: Panel drive circuit D1~D6, DQ Bu DQ2: Diode 15 201143516 EAl, EA2: Error amplifier 0P1: Operational amplifier R1~ R12: resistor

Ul、U2 : PWM控制器Ul, U2: PWM controller

Vac :交流電壓Vac : AC voltage

Vfbl :第一迴授電壓Vfbl: the first feedback voltage

Vin :第一直流電壓Vin: the first DC voltage

Vr7 :檢測電壓Vr7: detection voltage

Vref2 :閾值電壓 DIM1、DIM1’ ：反相調光信號 FB :迴授端信號 0N/0FF :開關信號 T :調光週期Vref2: threshold voltage DIM1, DIM1': inverting dimming signal FB: feedback terminal signal 0N/0FF: switching signal T: dimming period

Toff :關閉期間 L1 :電感器 Q1〜Q8 :電晶體 T1 :變壓器 I lamp :燈管電流Toff: off period L1: inductor Q1~Q8: transistor T1: transformer I lamp : lamp current

Vdcl〜Vdc5 :直流電壓Vdcl~Vdc5: DC voltage

Vfb2 :第二迴授電壓Vfb2: second feedback voltage

Vout :第二直流電壓Vout: second DC voltage

Vrefl :參考電壓籲 DIM :調光信號 DIM2 :同相調光信號 LVDS :控制信號 PWM1、PWM2 : PWM 信號Vrefl : Reference voltage Call DIM : Dimming signal DIM2 : In-phase dimming signal LVDS : Control signal PWM1, PWM2 : PWM signal

Ton :開啟期間 16Ton: On period 16

Claims

201143516 七、申請專利範圍： 1. $早串發光二極體燈f的驅動電路，該單一輸入端及一輪出矬赞九一極體燈管具有、艰_知’該早串發光二歸燈管的驅動電路包括：調光控制電路，接收脈寬調變一週期包括—開啟期間及二閉破’該調先信號每一電流迴授電路’與該調光控制電路串聯雛於端之間，在該開啟期間，該調光控制電路控制該:=== 檢測到該單串發光二極體燈 =該調光控制電路控制該輸出端與該接地 =:關= 電流迴授電路未檢_該燈管電流崎變控制電路’減至該迴授端，在接收職第—迴授電壓寺，出相位i⑽度的寬調變信號，在接收到該第二迴授堅時停止輸出該些脈寬調變信號；以及一推挽式轉換器，輕接至該輸入端及該脈寬調變控制電路，在接收到該些脈寬調變信號時據以將輸入的一第一直流電麼升壓為一第二直流電壓以輸出至該輸入端’在未接收到該些脈寬調變信號時停止轉換而不再輸出該第二直流電壓。 σ， 2.如申請專利制第丨項所述之單串發光二極體燈管的驅動電路，其中該脈寬調變控制電路包括： ^ -脈寬調變控制H ’包括-誤差放大II，該誤差放Α|§具有兩輸入端及一輸出端，其中一輸入端耦接至該迴授端，另一輸入端接收一參考電壓，該參考電壓等於該第一迴授電壓且小於該第二迴授 17 201143516 電壓’該誤差放大器在該迴授端的電壓等於該參考電壓時控制該脈寬調變控制器輸出該些脈寬調變信號，在該迴授端的電壓大於 »玄參考電壓時控制δ玄脈寬调變控制器停业輸出該些脈寬調變信號；以及一 " -電阻電容補償電路，祕於該誤差放Α||的—輸人端及該誤差放大器的輸出端之間，使該誤差放大器為負迴授架構。 3.述之單•發光二極體燈管嶋電路，其一第一單向導通元件；一目=，接收該調光信號，並輸出與該調光信號反相的— 調光信號通過該第—單向導通元件輕接至端^該嶋至該迴授一流迴授串軸接於該輸出端及該接地端之間，根據該问相調光信號在該開啟期間開啟以二勝在該__^__^= t該電流迴授所通之平串發光二極_管_動電路，其一第二單向導通元件；以及爾地端 —爾__=^= 201143516 一迴授電壓至該迴授端’在該關閉期間停止輸出該第一迴授電壓至該迴授端。 5.如申請專利範圍第1項所述之單串發光二極體燈管的驅動電路，更包括一開關控制電路’該開關控制電路輕接至該脈寬調變控制電路，接收一開關信號’根據該開關信號控制該脈寬調變控制電路是否工作。 6.如申請專利範圍第1項所述之單串發光二極體燈管的驅動電路，更包括一過壓保護電路，該過壓保護電路耦接至該輸入端及該脈寬調變控制電路’在該第二直流電壓大於一閾值電壓時控制該脈寬調變控制電路停止輸出該些脈寬調變信號。 7. 如申請專利範圍第1項所述之單串發光二極體燈管的驅動電路，其中該單串發光二極體燈管適用於一液晶顯示器的背光。 8. 如申請專利範圍第7項所述之單串發光二極體燈管的驅動電路，其中該液晶顯示器包括一液晶螢幕。 9. 先二極體燈管的_路，其201143516 VII. Patent application scope: 1. The drive circuit of the early string light-emitting diode lamp f, the single input end and one round of the 矬九九九九一具有具有该该该该该该该该The driving circuit of the tube comprises: a dimming control circuit, and receiving the pulse width modulation one cycle includes: during the opening period and the second closing period, the current signal feedback circuit is connected in series with the dimming control circuit During the opening period, the dimming control circuit controls the:=== detecting the single-string LED lamp=the dimming control circuit controls the output terminal and the grounding=:off=current feedback circuit is not detected _ The lamp current ramp control circuit 'reduced to the feedback terminal, in the receiving position - feedback voltage temple, the phase i (10) degree wide modulation signal, stop receiving output when receiving the second feedback a pulse width modulation signal; and a push-pull converter, which is connected to the input terminal and the pulse width modulation control circuit, and receives a first DC power when receiving the pulse width modulation signals Boost to a second DC voltage to output to the input The terminal 'stops switching when the pulse width modulation signals are not received and no longer outputs the second DC voltage. σ, 2. The driving circuit of the single-string LED lamp according to the above-mentioned patent application, wherein the pulse width modulation control circuit comprises: ^ - pulse width modulation control H 'including-error amplification II The error has a two-input and an output, wherein one input is coupled to the feedback terminal, and the other input receives a reference voltage, the reference voltage being equal to the first feedback voltage and less than the The second feedback 17 201143516 voltage 'the error amplifier controls the pulse width modulation controller to output the pulse width modulation signals when the voltage of the feedback terminal is equal to the reference voltage, and the voltage at the feedback terminal is greater than the » reference voltage The control δ Xuan pulse width modulation controller is shut down to output the pulse width modulation signals; and a " resistor-capacitor compensation circuit is secreted to the error input || the input terminal and the output end of the error amplifier Between, the error amplifier is made into a negative feedback architecture. 3. The single-light-emitting diode lamp 嶋 circuit, a first one-way conduction component; one mesh=, receiving the dimming signal, and outputting a dimming signal inverting the dimming signal through the first - the unidirectional conduction element is lightly connected to the end ^ the 嶋 to the feedback first-class feedback string is connected between the output end and the ground end, according to the phase dimming signal is turned on during the opening period to win __^__^= t The current is fed back to the flat-line LED 2 _ tube _ dynamic circuit, a second unidirectional conduction element; and the ground end - __ = ^ = 201143516 a feedback voltage Up to the feedback terminal 'stops outputting the first feedback voltage to the feedback terminal during the shutdown period. 5. The driving circuit of the single-string LED lamp according to claim 1, further comprising a switch control circuit that is lightly connected to the pulse width modulation control circuit to receive a switch signal 'Control whether the pulse width modulation control circuit operates according to the switching signal. 6. The driving circuit of the single-string LED lamp of claim 1, further comprising an overvoltage protection circuit coupled to the input terminal and the pulse width modulation control The circuit 'controls the pulse width modulation control circuit to stop outputting the pulse width modulation signals when the second DC voltage is greater than a threshold voltage. 7. The driving circuit of the single-string LED lamp of claim 1, wherein the single-string LED lamp is suitable for backlighting of a liquid crystal display. 8. The driving circuit of a single-string light-emitting diode lamp according to claim 7, wherein the liquid crystal display comprises a liquid crystal screen. 9. The first diode lamp _ road, its

驅動電路，其 10. 利範圍第7項所述之單串發光二極體燈管的中該液曰曰顯不器包括一一體機電腦。A driving circuit, wherein the liquid crystal display of the single-string LED lamp of the seventh aspect of the invention comprises an all-in-one computer.