200905631 九、發明說明： 【發明所屬之技術領域】 本發明是有關於一種多燈管平衡驅動電路，尤指一種以交變 式咼壓串接燈管的方式驅動複數個燈管的電路，且特別是有關於 用於液晶顯示器中之冷陰極燈管者。 【先前技術】200905631 IX. Description of the Invention: [Technical Field] The present invention relates to a multi-lamp balanced drive circuit, and more particularly to a circuit for driving a plurality of lamps by means of alternating squeezing and connecting lamps, and In particular, it relates to cold cathode lamps used in liquid crystal displays. [Prior Art]
液晶顯示器(Liquid crystal display, LCD)是屬於一種非自體 性發光顯示器’所以必須藉助背光模組(Backlightm〇dule)提供一 穩定光源，目前顯示器市場上以冷陰極燈管(c〇ld cath〇de fluorescent lamp，CCFL)為最佳背光源。 由於燈管工作在背光模朗，燈管會射賴組金屬導電外 殼產生許多寄生電容，且寄生電容值會因為燈管擺設位置不 同而有所差異’寄生電容存在形成錢路徑導致漏電流發生，造 成燈管與燈管之流麵差異性，使得燈管發出的光源強 度有明暗不均的_呈現，影_示㈣顯像品f ;因此，如何 使冷陰極燈管能提供料又敎的光源，各箱討的重點。 加以專利前案的燈管驅動電路架構有：推挽式並聯譜振換流器 木構半橋#振換流II架構及全橋她移換流轉構，例如纖 =月9日公告之美國專利公報第7〇42171 B1號中批露之一驅 梅_提解—錄輸瓣點亮。隨著顯示 器尺寸的加大，燈管長度的增加，對於元件所_耐壓與耐流特 200905631 财尤隨之增加’傳統的單高壓驅動架構，因寄生電容效應，使得 燈吕问低壓端電流不平衡現象會隨燈管長度增加而更加明顯。 第一圖是習知技術之中華民國專利公報第125427〇號中批露 之電路示意圖。電路包含N個燈管(40)，及N+1個變壓器(2〇1)， '父爰汛號至變壓盗(201)，並輸出一交變高壓訊號，在燈管 (40)兩端提供—相位相反、大小相同之交變高屢驅動燈管_，為 確保k官(40)電流及亮度能穩定，在燈管(4())及變壓器(施)間串 〇 接一電流平衡控制電路(50)。此習知技術不考慮燈管置入液晶顯 示器中’燈管與金屬導電外殼產生許多寄生電容，且這些寄生電 容值會因為燈管擺設位置不同而有所差異，造成燈管與燈管之間 發出的光源強度有明暗不均的問題呈現。第二圖是f知技術之側 光型背光職設方式，因驗管擺設位置的對雛，使得燈管& 及燈管c對金屬導電外殼有相同的寄生電容值，燈管b及燈管d 料f外殼有另-相_寄生電容值。第三圖是f知技術之 " 直下型背光源擺設方式’燈管a及燈管c對金屬導電外殼有相同 的寄生電容值’燈管b及燈管d對金屬導電外殼有另一相同的寄 生電容值。因此’設計多燈管之鶴電路必綱保這些燈管彼此 間之電流為均流，並同時兼顧元件的耐壓與财流條件之問題，便 是目前業界所亟需解決之課題。 200905631 【發明内容】 由上述說明可知，#燈管置人液晶顯㈣時，不{避免地在 燈管與金屬導電外賴產生有寄生電容，導軸减流的產生， 進而影響舰管電紅抑，紐管發光切雜；且實際連接 一共振電容的作法’亦必須花費較高的電路設計成本。 有鑑於此’本發明的目的在提供一種燈管驅動電路，不僅毋 須連接一實體共振電容及共振電感，還可以毋須連接一電流平衡 控制電路，即可解決驅動多燈管之情況下，燈管彼此間之電流不 平衡之問題，並可同時兼顧元件的耐壓與耐流條件之問題。 【實施方式】 請參考第四圖所示，本發明一較佳實施例。此電 路包含有： 一換流器驅動單元（1 〇) ’係包含一直流電壓源 (Vdc)及一換流器（11) ’該換流器（11)係連接該直流電 墨源（vdc) ’可將其輸入之直流電壓轉換成—交變電壓 (VAB)；Liquid crystal display (LCD) is a kind of non-autoluminescent display. Therefore, it is necessary to provide a stable light source by means of a backlight module (Backlightm〇dule). Currently, the display is on the market with a cold cathode lamp (c〇ld cath〇). De fluorescent lamp, CCFL) is the best backlight. Since the lamp works in the backlight mode, the lamp will generate a lot of parasitic capacitances due to the metal conductive casing, and the parasitic capacitance value will be different due to the different positions of the lamp arrangement. The difference between the flow surface of the lamp tube and the lamp tube is caused, so that the intensity of the light source emitted by the lamp tube is unevenly displayed, and the image shows (4) the image product f; therefore, how to make the cold cathode lamp tube provide the material and the material Light source, the focus of each box. The lamp drive circuit structure of the patented case is: push-pull parallel-spectral converter, wooden half-bridge, vibration-transfer II structure, and full-bridge, her-shifting, such as the US patent announced on the 9th of the month. In the bulletin No. 7〇42171 B1, one of the ones disclosed was unveiled. As the size of the display increases, the length of the lamp increases, and the voltage and resistance of the component are increased. The traditional single high-voltage drive architecture, due to the parasitic capacitance effect, makes the lamp low-voltage current Unbalance will become more pronounced as the length of the tube increases. The first figure is a circuit diagram disclosed in the conventional technology of the Republic of China Patent Gazette No. 125427. The circuit comprises N lamps (40), and N+1 transformers (2〇1), 'father nickname to variable pressure thief (201), and outputs an alternating high voltage signal, in the lamp tube (40) two The end provides - the opposite phase, the same size of the alternating high-speed drive lamp _, in order to ensure that the k official (40) current and brightness can be stabilized, a current is connected between the lamp (4 ()) and the transformer (application) Balance control circuit (50). This prior art does not consider that the lamp is placed in the liquid crystal display. The lamp and the metal conductive casing generate a lot of parasitic capacitance, and the value of these parasitic capacitances will vary depending on the position of the lamp, resulting in a relationship between the lamp and the lamp. The intensity of the emitted light source is manifested by the problem of uneven brightness. The second picture is the side-light type backlighting mode of the technology, because the position of the tube is set, so that the tube & and the tube c have the same parasitic capacitance value for the metal conductive shell, the lamp b and the lamp The tube d material f has a different phase-to-parasitic capacitance value. The third picture is the "follow-up type backlight arrangement" 'light tube a and tube c have the same parasitic capacitance value for the metal conductive housing' lamp b and tube d have another identical to the metal conductive housing The parasitic capacitance value. Therefore, the design of a multi-lamp crane circuit must ensure that the currents of these lamps are current-sharing, and at the same time take into account the problem of component withstand voltage and financial flow conditions, which is an urgent problem to be solved in the industry. 200905631 [Disclosed from the above] It can be seen from the above description that when the #lamp is placed in the liquid crystal display (4), the parasitic capacitance is not avoided in the lamp tube and the metal conduction, and the guide shaft reduces the flow, thereby affecting the ship tube red In other words, the neon tube emits light and is complicated; and the practice of actually connecting a resonant capacitor must also cost a high circuit design. In view of the above, the object of the present invention is to provide a lamp driving circuit that not only does not need to be connected with a solid resonant capacitor and a resonant inductor, but also can be connected to a current balancing control circuit, thereby solving the problem of driving a plurality of lamps. The problem of current imbalance between each other, and the problem of the withstand voltage and current resistance of the component can be considered at the same time. [Embodiment] Please refer to the fourth figure for a preferred embodiment of the present invention. The circuit comprises: an inverter drive unit (1 〇) 'includes a DC voltage source (Vdc) and a converter (11) 'The converter (11) is connected to the DC ink source (vdc) 'It can convert its input DC voltage into - alternating voltage (VAB);
一升壓變壓器（20) ’係包含--次侧及一由2N 繞組所構成之二次側，該一次側係連接前述換流器驅 動單元（10)之換流器（11) ’前述交變電壓（Vab)經過電 磁感應升壓後，由該二次側的其中N繞組各感應一輸 出交變電壓，剩餘N繞組各感應一相位相反、大小相 同之輸出交變電壓； 200905631 一共振電路（30)，請參考第五圖所示，為第四圖 之等效電路，包含共振電感（Lr)、兩寄生電容（Cl及 C，2)串接，共振電感（Lr)係一端分別連接前述升壓變壓 f§(20)二次側繞組之一端，兩寄生電容π:及分別 為不㈣管位置與金屬導電外殼⑷）之等效電容值， 且寄生電容兩端分別連接燈管與金屬導電外殼； ΟA step-up transformer (20) 'includes a secondary side and a secondary side formed by a 2N winding, and the primary side is connected to the inverter (11) of the inverter drive unit (10). After the voltage is boosted by the electromagnetic induction, the N windings of the secondary side respectively induce an output alternating voltage, and the remaining N windings respectively induce an output alternating voltage of opposite phase and the same magnitude; 200905631 A resonant circuit (30), please refer to the fifth figure, which is the equivalent circuit of the fourth figure, including the resonant inductor (Lr), two parasitic capacitors (Cl and C, 2) connected in series, and the resonant inductor (Lr) is connected at one end. The boosting voltage f§(20) one end of the secondary winding, the two parasitic capacitances π: and the equivalent capacitance values of the (four) tube position and the metal conductive shell (4), respectively, and the two ends of the parasitic capacitor are respectively connected to the lamp tube With metal conductive housing; Ο
C 、且g (40)，係包含n支燈管（4〇),燈管之内 =阻均為⑻’兩端分別連接至前述共振電感（Lr)之 :及升壓’交壓器(2〇)二次侧繞組之一端，該升壓變 器:20)二次！繞組之另一# ’連接另一燈管 :J、、串f燈官之選擇’以大寄生電容值的燈管串接 2生電容值的燈管方式’依序形成迴路，即可不需 控制電路，使所有燈管通過相同電流及發出 上述電路說明如下，拖、ώ (vdc)轉換成— 、广^11)係將—直流電麗 分別輪出兩相位相二Γ;β，π升娜器(2°) =電路㈣分別輸至冷陰極燈管 = 振盪點亮該燈管（40)。 鳊進而 效電：圖所示，為燈管於雙高墨驅動下之等 璧：=，，；燈管Γ)兩端相位相反、大小相同之ί 了視燈管（40)之中心為声接士 將燈管（4_部電阻等虛接地點’是以， 地端的茂漏電流(R/2)’ μ出系統 电瓜（i】eakage)因雙局壓極性相反而減為 8 200905631 令。本發明特徵在於不需使用實體共振電容，而是利 用燈官（40)與金屬外殼（41)間會形成寄生電容 之)的現象’量测計算出該寄生電容值’進而以寄生 合（Cl及C2)做為共振元件，取代習知電路原本 的實體共振f容。 ^本具有 曰凊參考第六圖所示，為本發明一較佳實施例的 :量測波形’燈管電流均在8mA附近，最大與最小電 流差距在0.15mA’第四圖的燈管電流平衡性非常良 Γι;:時ί屬導電外殼與系統地端洩漏電流值為 〇 mA，表示ΕΜΙ將大幅降低。 :者’因升壓變壓器(2〇)本身具有茂漏電感，故 可：茂漏電感取代原本電路之共振電感I)做為共振 兀：’此該升壓變壓器(2〇)之細感可以由製造商 配合設計出。 衣^陶 —、、VT、上所述，本發明係藉由利用非有形體之寄生 :及雜散電感做為共振元件，將可減少共振電路所需 量，達到節省成本之功效…兩相鄰串接 以該燈管與背光模組金屬導電外殼形成 咮雷A電谷為依據’以大寄生電容值的燈管串接小寄 控燈管方式，依序形成迴路，不需電流平衡 ρ可使所有燈管通過相同電流及發出相同 :二倍本發明之多燈官之均流設計具有低成本及高性 月匕的優點，是習知技術所無法達成的。 200905631 【圖式簡單說明】 第一 圖 •係既有燈管之電 路示意 圖 0 第二 圖 係既有側光型背 光源擺 設 方 式。 第三 圖 係既有直下型背 光源擺 設方 式。 第四 圖 係本發明一較佳 實施例 之 電 路示 第五 圖 係本發明一較佳 實施例 之 等 效電 第六 圖 燈管穩態輸出波形。 【主要元件符號說明】 (11)換流器 (30)共振電路 (41)金屬導電外殼 (201)變壓器 (10)換流器驅動單元 (20)升壓變壓器 (40)燈管 (50)電流平衡控制電路 (Lr)共振電感 (C〇 (C2)寄生電容 (Ra) (Rb) (Rc) (Rd)燈管a〜d之内部電阻C and g (40), including n lamps (4 〇), inside the lamp = resistance are (8) 'the two ends are respectively connected to the aforementioned resonant inductor (Lr): and the boosting 'voltage regulator ( 2〇) One end of the secondary winding, the booster: 20) twice! The other one of the windings is connected to another lamp: J, the string of the lamp's choice of 'the lamp with a large parasitic capacitance value connected in series with the 2 capacitor value' sequentially forms a loop, which can be controlled without control. The circuit, so that all the lamps pass the same current and the above circuit is explained as follows, drag, ώ (vdc) is converted into -, 广^11)------------------------------------------------------ (2°) = circuit (4) is sent to the cold cathode lamp separately = oscillates the lamp (40).鳊 鳊 效 : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : The receiver will light the tube (the virtual ground point of the 4_ part resistor is ', the leakage current at the ground end (R/2)' μ system electric melon (i) oakage) is reduced to 8 due to the opposite polarity of the double local pressure. 200905631 The present invention is characterized in that the phenomenon of parasitic capacitance is calculated by measuring the phenomenon of parasitic capacitance between the lamp official (40) and the metal casing (41) without using a physical resonance capacitor, and then parasitic (Cl and C2) act as a resonant element, replacing the original physical resonance f-capacitance of the conventional circuit. The present invention has a reference to the sixth embodiment, which is a preferred embodiment of the present invention: the measurement waveform 'the lamp current is around 8 mA, and the maximum and minimum current difference is 0.15 mA'. The balance is very good Γ;: ί is the conductive shell and the system ground leakage current value is 〇 mA, indicating that ΕΜΙ will be greatly reduced. : 'Because the step-up transformer (2〇) itself has a leakage inductance, it can be: the leakage inductance replaces the resonant inductance of the original circuit I) as a resonance 兀: 'The fineness of the step-up transformer (2〇) can be Designed by the manufacturer. The invention is based on the use of non-tangible parasitic and stray inductance as a resonant element, which can reduce the amount of resonance circuit required and achieve cost saving effect. The adjacent series is connected with the metal conductive shell of the lamp tube and the backlight module to form a 咮雷 A electric valley. The lamp with a large parasitic capacitance value is connected in series with a small control lamp tube, and sequentially forms a loop without current balance ρ. All the lamps can pass the same current and emit the same: twice the multi-lamp design of the present invention has the advantages of low cost and high monthly efficiency, which cannot be achieved by conventional techniques. 200905631 [Simple description of the diagram] The first figure is a schematic diagram of the circuit of the existing lamp. Fig. 2 The second figure is the sidelight type backlight arrangement. The third picture has both a direct-type back light source setting. The fourth embodiment is a circuit diagram of a preferred embodiment of the present invention. The fifth embodiment is a steady-state output waveform of the lamp of the sixth embodiment of the present invention. [Main component symbol description] (11) Inverter (30) Resonant circuit (41) Metal conductive housing (201) Transformer (10) Inverter drive unit (20) Step-up transformer (40) Lamp (50) Current Balance Control Circuit (Lr) Resonant Inductance (C〇(C2) Parasitic Capacitance (Ra) (Rb) (Rc) (Rd) Internal Resistance of Lamps a to D