1300674 九、發明說明： 【發明所屬之技術領域】 v 本發明涉及一種放電燈驅動裝置，尤其涉及一種應用於 、 液晶顯示器（liquid crystal display, LCD)背光源模組 之放電燈驅動裝置。 【先前技術】 目前，液晶顯示器（LCD)的面板主要採用放電燈 (Discharge Lamp)作為背光源，該種燈管需要較高的驅動 | 電壓才可以點亮。隨著LCD面板尺寸向大型化方向的發展， 則需要使用複數燈管來提供足夠的亮度。 第一圖所示為習知放電燈驅動裝置，習知放電燈驅動裝 置主要係由開關電路10、變壓電路11、燈管組12、迴授電 路 13 與脈寬調變（pulse Width Modulation，PWM)控制器 14所組成。開關電路ι〇將接收到的直流電源訊號轉換為一 交流訊號，變壓電路11將該交流訊號轉換為可驅動燈管組 12之弦波訊號，迴授電路13連接於燈管組12與PWM控制器 14之間，將流經燈管組12之電流迴授至pwm控制器14, PWM 控制器14根據迴授電路13之輸出來控制開關電路1〇之交 > 流輸出訊號，進而控制流經燈管組12之電流大小。 習知放電燈驅動裝置架構之迴授訊號係取自燈管組12 之低壓端’對於背光模組廠商來說，迴授訊號需要藉助外部 線路將迴授電流自燈管組12引向放電燈驅動裝置，因此成 本較高。 第二圖所示為另一習知放電燈驅動裝置，其與第一圖放 電燈驅動裝置區別在於迴授電路23連接於變壓電路21之輸 出端與PWM控制器24之間，迴授訊號係取自變壓電路21之 輸出端。電流迴授訊號無須藉助外部線路，只需在放電燈驅 動裝置内部即可完成’較節約成本。然、，在變壓電路21輸 6 1300674 出端取得迴授訊號會使燈管組22輪出電流不穩定，這樣會 影響迴授訊號選取的精確度。 【發明内容】 有鐘於此，需提供一種放電燈驅動裝置，其從放電燈驅 動裝置之輸入端電路取得迴授訊號，可節約成本，並提高精 確度。 一種放電燈驅動裝置，用於驅動一燈管組，包括一開關 電路、一變壓電路、一電壓感測電路、一電流感測電路以及 一 PWM控制器。開關電路用以將接收到的一直流電源訊號轉 換為一交流訊號。變壓電路用以將該交流訊號轉換為可驅動 燈管組之另一交流訊號。電壓感測電路用以接收該直流電源 訊號，並感測該直流電源訊號之電壓。電流感測電路用以接 收該直流電源訊號，並感測該直流電源訊號之電流。PWM控 制器根據感測到的電壓與電流控制該開關電路之交流輸出 訊號。 【實施方式】 第三圖係本發明之一實施例之放電燈驅動裝置，該放電 燈驅動裝置包括一開關電路30、一變壓電路31、一燈管組 32、一 PWM控制器33、一電壓感測電路34及一電流感測電 路35。 開關電路30用以將接收到的一直流電源訊號轉換為一 交流訊號，變壓電路31將該交流訊號轉換為可驅動燈管組 32之另一交流訊號。電壓感測電路34用以接收該直流電源 訊號，並感測該直流電源訊號之電壓。電流感測電路35用 以接收該直流電源訊號，並感測該直流電源訊號之電流。PWM 控制器33根據感測到的電壓與電流控制開關電路30之交流 輸出訊號，進而控制流經燈管組32之電流。 進一步而言，PWM控制器33係根據感測到的電壓與電 7 1300674 流維持該放電燈驅動裝置之輸入功率為一恆定值，1300674 IX. Description of the Invention: [Technical Field] The present invention relates to a discharge lamp driving device, and more particularly to a discharge lamp driving device applied to a liquid crystal display (LCD) backlight module. [Prior Art] At present, the panel of a liquid crystal display (LCD) mainly uses a discharge lamp (Discharge Lamp) as a backlight, and the lamp requires a high driving voltage to illuminate. As the size of LCD panels has increased in size, multiple lamps are needed to provide sufficient brightness. The first figure shows a conventional discharge lamp driving device. The conventional discharge lamp driving device is mainly composed of a switching circuit 10, a transformer circuit 11, a lamp group 12, a feedback circuit 13, and a pulse width modulation (pulse width modulation). The PWM) controller 14 is composed of. The switching circuit ι converts the received DC power signal into an AC signal, and the transformer circuit 11 converts the AC signal into a sine wave signal that can drive the lamp group 12, and the feedback circuit 13 is connected to the lamp group 12 and the PWM. Between the controllers 14, the current flowing through the lamp group 12 is fed back to the pwm controller 14, and the PWM controller 14 controls the switching circuit 1 according to the output of the feedback circuit 13 to output a stream output signal, thereby controlling The amount of current flowing through the tube group 12. The feedback signal of the conventional discharge lamp driving device architecture is taken from the low voltage end of the lamp group 12. For the backlight module manufacturer, the feedback signal needs to be externally routed to direct the feedback current from the lamp group 12 to the discharge lamp. The drive unit is therefore costly. The second figure shows another conventional discharge lamp driving device, which is different from the first discharge lamp driving device in that the feedback circuit 23 is connected between the output end of the transformer circuit 21 and the PWM controller 24, and the feedback signal is provided. It is taken from the output of the transformer circuit 21. The current feedback signal does not need to be externally connected, and it can be done inside the discharge lamp driver. However, obtaining the feedback signal at the output of the transformer circuit 21 at the output of the 1300674 will make the current of the lamp group 22 unstable, which will affect the accuracy of the feedback signal selection. SUMMARY OF THE INVENTION There is a need to provide a discharge lamp driving device that obtains a feedback signal from an input terminal circuit of a discharge lamp driving device, thereby saving cost and improving accuracy. A discharge lamp driving device for driving a lamp group includes a switching circuit, a transformer circuit, a voltage sensing circuit, a current sensing circuit and a PWM controller. The switch circuit is configured to convert the received DC power signal into an AC signal. The transformer circuit is used to convert the AC signal into another AC signal that can drive the lamp group. The voltage sensing circuit is configured to receive the DC power signal and sense the voltage of the DC power signal. The current sensing circuit is configured to receive the DC power signal and sense the current of the DC power signal. The PWM controller controls the AC output signal of the switching circuit based on the sensed voltage and current. [Embodiment] The third embodiment is a discharge lamp driving device according to an embodiment of the present invention. The discharge lamp driving device includes a switching circuit 30, a transformer circuit 31, a lamp group 32, a PWM controller 33, and a The voltage sensing circuit 34 and a current sensing circuit 35. The switching circuit 30 is configured to convert the received DC power signal into an AC signal, and the transformer circuit 31 converts the AC signal into another AC signal that can drive the lamp group 32. The voltage sensing circuit 34 is configured to receive the DC power signal and sense the voltage of the DC power signal. The current sensing circuit 35 is configured to receive the DC power signal and sense the current of the DC power signal. The PWM controller 33 controls the AC output signal of the switch circuit 30 based on the sensed voltage and current to control the current flowing through the lamp group 32. Further, the PWM controller 33 maintains the input power of the discharge lamp driving device to a constant value according to the sensed voltage and the power of the current.
加載在，管組32之功率為—恒定值，確保流經燈管組32之 電流穩電流制電路35與關電路30相連，用於㈣ -電流迴路。本實施方式中，關電路3Q輸出之交^ 係-=波訊號’變壓電路31輸出之交流訊號係—弦波^^ 第四圖係本發明第三圖之具體電路圖。其中，雷u 31為-變壓器T，其具有一初級繞組與一次級繞組，初級繞 組與開關電路3M目連接，次級繞組之—端與燈管組32 = 連，另一端接地。本實施方式中，變壓器了初級繞組之 電路係本發明放紐軸裝置之輸人端電路，其:欠級繞組之 後端電路係本發明放電燈驅動裝置之輸出端電路。儿、 開關電路30包括電晶體Ml、M2與電容Cl、C2，於本杏 施例中，電晶體Ml、M2為主要開關元件，其以半& (half-bridge)的$式連接在一起，作糊關之作用。本 方式中’電晶體Ml、M2係金屬氧化物半導體場效應電 日日體（Metal-Oxide-Semiconductor Field Effect T_istor，MOSFET)。電容C1連接於電晶體M1之沒極與 變壓器τ初級繞組之-端之間，電容C2連接於電晶體似之 源極與變壓Is T初級繞組之n。電晶體M1之源極與 電，體M2之汲極相連，並同時連接變壓器τ初級繞組之另 -端。電晶體ΜΙ、M2之柵極分別連接至pwM控制器33。本 發明之其他實施方式中，開關電路3〇亦可為全橋式 (full-bridge)架構、推挽式（pull—push)架構以及自激 式（royer)架構。 電壓感測電路34包括一電壓感測電阻幻，其連接於電 ，體Ml之汲極與PWM控制器33之間，用以感測直流電源訊 號之電壓，並將感測到的電壓輸出至pWM控制器33。 8 1300674 電流感測電路35包括一電流感測電阻R2、一放大器A 及一電阻R3，其中，電流感測電阻R2連接於電晶體m2之源 極與地之間，用以感測直流電源訊號之電流。放大器A具有 一正極輸入端、一負極輸入端與一輸出端，該正極輸入端接 地’負極輸入端與電晶體M2之源極相連，輸出端連接ρψΜ 控制裔33。電阻R3連接於放大器a之負極輸入端與輸出端 之間。 由於輸入直流電流較大，為了不使電流感測電阻R2上 有過多功率損耗，則選取阻值較小之電流感測電阻R2，本實 施方式中，電流感測電阻R2阻值為25ιηΩ。放大器A將電流 感測電阻R2感測到的電流放大，並輸出至p醫控制器犯。 PWM控制器33根據感測到的電壓與電流調整其輸出pwM波形 之責任週期（Duty Cycle)，分別控制電晶體M1、M2之開關 時間，從而控制開關電路30之交流輸出訊號，確保放電燈 驅動裝置之輸入功率為一恆定值，使得流經燈管組32之 流穩定。 本發明之實施方式中，電壓與電流感測訊號取自放電燈 驅動裝置之輸入端電路，不但可以使背光模組廠商降低成 本，亦可使燈管組32低壓端電流穩定，保證迴授感測訊號 之精確度，進而確保電流調節之精確度。 本發明雖以較佳實施例揭露如上，然其並非用以限定本 f明。惟，任何熟悉此項技藝者，在不脫離本發明之精神和 範圍内，g可做更動與潤飾，因此本發明之保護範圍當視後 附之申請專利範圍所界定者為準。 【圖式簡單說明】 第一圖係習知放電燈驅動裝置； 第二圖係另一習知放電燈驅動裝置； 9 1300674 第三圖係本發明之一實施方式之放電燈驅動裝置 第四圖係本發明第三圖之具體電路圖。 【主要元件符號說明】 開關電路 變壓電路 燈管組 PWM控制器 電壓感測電路 電流感測電路 電阻 M0SFET電晶體 電容 30 31 32 33 34 35 Rl、R2、R3 Ml、M2 Cl、C2Loaded, the power of the tube set 32 is - constant, ensuring that the current stabilizing current circuit 35 flowing through the lamp group 32 is connected to the off circuit 30 for the (four) - current loop. In the present embodiment, the AC signal outputted by the switch circuit 3Q-==wave signal' transformer circuit 31 is outputted as a specific circuit diagram of the third figure of the present invention. Wherein, the thule 31 is a transformer T having a primary winding and a primary winding, the primary winding is connected to the switching circuit 3M, the end of the secondary winding is connected to the lamp group 32 = and the other end is grounded. In the present embodiment, the circuit of the primary winding of the transformer is the input terminal circuit of the open shaft device of the present invention, and the rear end circuit of the lower winding is the output circuit of the discharge lamp driving device of the present invention. The switching circuit 30 includes transistors M1 and M2 and capacitors C1 and C2. In the embodiment of the apricot, the transistors M1 and M2 are main switching elements, which are connected by a half-and-half (half-bridge) type. For the role of paste. In the present embodiment, the transistors M1 and M2 are Metal-Oxide-Semiconductor Field Effect T_istors (MOSFETs). The capacitor C1 is connected between the terminal of the transistor M1 and the terminal of the primary winding of the transformer τ, and the capacitor C2 is connected to the source of the transistor and the n of the primary winding of the transformer Is T. The source of the transistor M1 is connected to the drain of the body M2 and is connected to the other end of the primary winding of the transformer τ. The gates of the transistor ΜΙ, M2 are connected to the pwM controller 33, respectively. In other embodiments of the invention, the switch circuit 3〇 may also be a full-bridge architecture, a push-pull architecture, and a self-excited architecture. The voltage sensing circuit 34 includes a voltage sensing resistor phantom connected between the drain of the body M1 and the PWM controller 33 for sensing the voltage of the DC power signal and outputting the sensed voltage to pWM controller 33. The current sensing circuit 35 includes a current sensing resistor R2, an amplifier A and a resistor R3. The current sensing resistor R2 is connected between the source of the transistor m2 and the ground for sensing the DC power signal. The current. The amplifier A has a positive input terminal, a negative input terminal and an output terminal. The positive input terminal is connected to the ground. The negative input terminal is connected to the source of the transistor M2, and the output terminal is connected to the control target 33. The resistor R3 is connected between the negative input terminal and the output terminal of the amplifier a. Since the input DC current is large, in order not to cause excessive power loss on the current sensing resistor R2, the current sensing resistor R2 having a small resistance value is selected. In the embodiment, the current sensing resistor R2 has a resistance value of 25 ιηΩ. Amplifier A amplifies the current sensed by current sense resistor R2 and outputs it to the p-controller. The PWM controller 33 adjusts the duty cycle of the output pwM waveform according to the sensed voltage and current, respectively controls the switching time of the transistors M1 and M2, thereby controlling the AC output signal of the switching circuit 30 to ensure the discharge lamp driving. The input power of the device is a constant value such that the flow through the tube stack 32 is stabilized. In the embodiment of the present invention, the voltage and current sensing signals are taken from the input circuit of the discharge lamp driving device, which not only can reduce the cost of the backlight module manufacturer, but also stabilize the current of the low voltage end of the lamp tube group 32, and ensure the sense of feedback. The accuracy of the test signal ensures the accuracy of the current regulation. The present invention has been described above in terms of preferred embodiments, and is not intended to limit the invention. However, any person skilled in the art can make modifications and refinements without departing from the spirit and scope of the invention, and the scope of the invention is defined by the scope of the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS The first figure is a conventional discharge lamp driving device; the second figure is another conventional discharge lamp driving device; 9 1300674 The third drawing is a fourth embodiment of a discharge lamp driving device according to an embodiment of the present invention. It is a specific circuit diagram of the third figure of the present invention. [Main component symbol description] Switching circuit Transformer circuit Lamp group PWM controller Voltage sensing circuit Current sensing circuit Resistance M0SFET transistor Capacitance 30 31 32 33 34 35 Rl, R2, R3 Ml, M2 Cl, C2