JP2010205716A

JP2010205716A - Lamp driving system

Info

Publication number: JP2010205716A
Application number: JP2009188314A
Authority: JP
Inventors: Tsu-Hua Ai; アイツ−フア
Original assignee: Taida Electronic Industry Co Ltd
Current assignee: Taida Electronic Industry Co Ltd
Priority date: 2009-03-05
Filing date: 2009-08-17
Publication date: 2010-09-16
Also published as: TW201034518A

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lamp driving system for driving a cold-cathode fluorescent lamp. <P>SOLUTION: The lamp driving system includes a first driving module. The first driving module includes a first transformer, a first capacitor and a first current-detecting circuit. The first transformer has a first primary side and a first secondary side. The first secondary side has a first terminal and a second terminal. The first terminal is connected to a first side of the lamp. An end of the first capacitor is connected to the first terminal and the lamp. The first current-detecting circuit includes a plurality of passive elements. An end of the first current-detecting circuit is connected to the second terminal. The other end of the first current-detecting circuit is connected to the other end of the first capacitor. The first current-detecting circuit has a first detecting point for detecting a first voltage. The first voltage is in direct proportion to a lamp-end current without containing capacitive current component of the lamp. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

本発明はランプ駆動システム、特に冷陰極蛍光ランプ(CCFL)を駆動するランプ駆動システムに関する。 The present invention relates to a lamp driving system, and more particularly to a lamp driving system for driving a cold cathode fluorescent lamp (CCFL).

図1は、従来技術による冷陰極蛍光ランプ駆動システムを図示する概略回路図である。図１に示すように、駆動回路１２は変圧器１４の一次側に接続されている。冷陰極蛍光ランプ１９は変圧器１４の二次側に接続されている。駆動回路１２により、ＤＣ電圧はＡＣ電圧に変換される。そのＡＣ電圧は変圧器１４により、冷陰極蛍光ランプ１９を駆動するために必要な高電圧、高周波数のＡＣ電圧に変換される。冷陰極蛍光ランプ１９は高電圧、高周波のＡＣ電圧で駆動されるため、漂遊キャパシターC_p による漏れ電流I_C が冷陰極蛍光ランプ１９の高電圧側で発生してしまう。漏れ電流I_C は、冷陰極蛍光ランプ１９の駆動電圧と駆動周波数とに正比例する進み位相の電流となる。冷陰極蛍光ランプ１９の低電圧側では、電圧と電流は同じ位相となる。冷陰極蛍光ランプ１９の低電圧側の電流は有効電力の電流成分となる。冷陰極蛍光ランプ１９の照明時間や環境は変化するものゆえに、冷陰極蛍光ランプ１９の温度も変化する。たとえランプの端子電流I_L を一定値に保ったとしても、温度の変化に従ってランプ電圧も変化してしまう。一般に、温度が上昇するとランプ電圧は低下する。 FIG. 1 is a schematic circuit diagram illustrating a conventional cold cathode fluorescent lamp driving system. As shown in FIG. 1, the drive circuit 12 is connected to the primary side of the transformer 14. The cold cathode fluorescent lamp 19 is connected to the secondary side of the transformer 14. The drive circuit 12 converts the DC voltage into an AC voltage. The AC voltage is converted by the transformer 14 into an AC voltage having a high voltage and a high frequency necessary for driving the cold cathode fluorescent lamp 19. Cold cathode fluorescent lamp 19 is a high voltage, to be driven at a high frequency of the AC voltage, the leakage current I _C by stray capacitor C _p occurs at a high voltage side of the cold cathode fluorescent lamp 19. The leakage current I _C is a lead phase current that is directly proportional to the drive voltage and drive frequency of the cold cathode fluorescent lamp 19. On the low voltage side of the cold cathode fluorescent lamp 19, the voltage and current have the same phase. The current on the low voltage side of the cold cathode fluorescent lamp 19 becomes a current component of active power. Since the illumination time and environment of the cold cathode fluorescent lamp 19 change, the temperature of the cold cathode fluorescent lamp 19 also changes. Even if the lamp terminal current I _L is kept at a constant value, the lamp voltage also changes as the temperature changes. In general, the lamp voltage decreases as the temperature increases.

図１を再度参照願いたい。冷陰極蛍光ランプ１９の低電圧側は接地されているため、フィードバック電流は冷陰極蛍光ランプ１９の高電圧側から取得される。フィードバック電流はランプ端子電流I_L と漏れ電流I_Cを含む。漏れ電流I_Cは温度変化とともに変化するものであるから、総合電流がランプ端子電流と漏れ電流の和(すなわち、I_H= I_L + I_C)と等しい関係が維持されるとしたら、ランプ端子電流I_L は逆の方向に変化させられる。このような状況になれば、冷陰極蛍光ランプ１９の輝度を一定に保つことが困難になる。図２は、図１で示された冷陰極蛍光ランプ１９の高電圧側と低電圧側に流れる関連の電流信号のタイミングを示す波形図である。図２に示されるように、漏れ電流I_C は進み位相電流であり、抵抗性のランプ端子電流I_L
より９０度進み位相となる。ランプ端子電流I_L とランプ電圧は同位相となる。 Please refer to FIG. 1 again. Since the low voltage side of the cold cathode fluorescent lamp 19 is grounded, the feedback current is acquired from the high voltage side of the cold cathode fluorescent lamp 19. Feedback current includes a lamp terminal current I _L and the leakage current I _C. Since the leakage current I _C changes with temperature, if the total current is kept equal to the sum of the lamp terminal current and leakage current (i.e., I _H = I _L + I _C ), then the lamp terminal The current I _L is changed in the opposite direction. In such a situation, it becomes difficult to keep the brightness of the cold cathode fluorescent lamp 19 constant. FIG. 2 is a waveform diagram showing timings of related current signals flowing on the high voltage side and the low voltage side of the cold cathode fluorescent lamp 19 shown in FIG. As shown in FIG. 2, the leakage current I _C is the lead phase current, and the resistive lamp terminal current I _L
The phase advances by 90 degrees. The lamp terminal current _IL and the lamp voltage have the same phase.

図３は従来形冷陰極蛍光ランプ駆動システムの他の例を示す概略回路図である。図３に示すように、インバーター２０は駆動回路２２と変圧器２４を含む。インバーター２０は出力電圧Vout と出力電流Iout を発生させる。変圧器２４の二次側から伝達される出力電流Iout に応じて、パルス幅変換制御器２６はインバーター２０に対してフィードバック制御信号を発生し、インバーター２０の出力を調整する。冷陰極蛍光ランプ２９は幾つかの漂遊キャパシターC₁, C₂₁, C₂₂,…, C_2n,を含むため、出力電流Iout はランプ端子電流I_L と第一の漂遊キャパシター電流I₁ と、第二の漂遊キャパシター電流I₂を合計したものとなる。フィードバック制御サンプリング回路は、実効電流値サンプリング制御器２８と、出力電流Ioutの実効電流値をサンプリングするためのスイッチ２７を含む。出力電流Ioutの実効電流値では、第一の漂遊キャパシター電流I₁ と、第二の漂遊キャパシター電流I₂を合計は最少値となり、このためランプ端子電流I_Lは出力電流Iout と非常に近い値になる。実効電流値を得るために、スイッチ２７は変圧器２４の二次側とパルス幅変換制御器２６の間に結合されて、実効電流値サンプリング制御器２８の入力端子は冷陰極蛍光ランプ２９の高電圧側に接続され、実効電流値サンプリング制御器２８の出力端子はスイッチ２７に接続される。冷陰極蛍光ランプ２９の高電圧側電圧Vout に応じて、実効電流値サンプリング制御器２８はサンプリング制御信号をスイッチ２７に発し、スイッチ２７の開閉動作を制御する。 FIG. 3 is a schematic circuit diagram showing another example of a conventional cold cathode fluorescent lamp driving system. As shown in FIG. 3, the inverter 20 includes a drive circuit 22 and a transformer 24. The inverter 20 generates an output voltage Vout and an output current Iout. In response to the output current Iout transmitted from the secondary side of the transformer 24, the pulse width conversion controller 26 generates a feedback control signal for the inverter 20, and adjusts the output of the inverter 20. Since the cold cathode fluorescent lamp 29 includes several stray capacitors C ₁ , C ₂₁ , C ₂₂ ,..., C _2n , the output current Iout is the lamp terminal current I _L , the first stray capacitor current I _1, and the first This is the sum of the _two stray capacitor currents I ₂ . The feedback control sampling circuit includes an effective current value sampling controller 28 and a switch 27 for sampling the effective current value of the output current Iout. The effective current value of the output current Iout, a first stray capacitor current I _1, the second total stray capacitor current I ₂ becomes minimum value, Therefore lamp terminal current I _L output current Iout and very close to become. In order to obtain the effective current value, the switch 27 is coupled between the secondary side of the transformer 24 and the pulse width conversion controller 26, and the input terminal of the effective current value sampling controller 28 is the high voltage of the cold cathode fluorescent lamp 29. Connected to the voltage side, the output terminal of the effective current value sampling controller 28 is connected to the switch 27. In response to the high voltage side voltage Vout of the cold cathode fluorescent lamp 29, the effective current value sampling controller 28 issues a sampling control signal to the switch 27 to control the opening / closing operation of the switch 27.

図４は、図３で示された実効電流値サンプリング制御器の概略ブロック図である。図４で示されるように、実効電流値サンプリング制御器２８は電圧分圧器２８２とピーク電圧検出回路２８４を含む。冷陰極蛍光ランプ２９の高電圧側電圧Vout は、電圧分圧器２８２によって分圧される。ピーク電圧検出回路２８４は分圧された電圧を受信、処理して、スイッチ２７のオン/オフ状態を制御するサンプリング制御信号を発生し、サンプリング動作が実行される。 FIG. 4 is a schematic block diagram of the effective current sampling controller shown in FIG. As shown in FIG. 4, the effective current value sampling controller 28 includes a voltage divider 282 and a peak voltage detection circuit 284. The high voltage side voltage Vout of the cold cathode fluorescent lamp 29 is divided by the voltage divider 282. The peak voltage detection circuit 284 receives and processes the divided voltage, generates a sampling control signal for controlling the on / off state of the switch 27, and performs a sampling operation.

図５は、図３で示される冷陰極蛍光ランプの高電圧側と低電圧側に流れる関連する電流信号を示すタイミング波形図である。変圧器２４の二次側の電流サンプリング回路は二次側の電流検出のために用いられる。容量性の漏れ電流I₁ はランプ端子電流I_L より９０度進み位相であり、実効電流値はランプ電圧Vout がピーク値で漏れ電流が零の時にサンプリングされ、フィードバックされる。このため、フィードバック電流はランプ端子電流I_L のみを含むことになる。その結果として、もし漏れ電流I₁+I₂
が温度変化によって変化したとしても、ランプ端子電流I_Lは影響を受けない。換言すれば、冷陰極蛍光ランプは温度が変化しても、同じ輝度を保持できる。 FIG. 5 is a timing waveform diagram showing related current signals flowing on the high voltage side and the low voltage side of the cold cathode fluorescent lamp shown in FIG. The current sampling circuit on the secondary side of the transformer 24 is used for current detection on the secondary side. Leakage current I ₁ of the capacitive is 90 degrees leading phase from the lamp terminal current I _L, the effective current value is sampled when the leakage current is zero the lamp voltage Vout is at a peak value, is fed back. Therefore, the feedback current will contain only the lamp terminal current I _L. As a result, if the leakage current I ₁ + I ₂
Even if changes due to temperature change, the lamp terminal current _IL is not affected. In other words, the cold cathode fluorescent lamp can maintain the same luminance even when the temperature changes.

以上に述べたランプ駆動システムにも、しかしまだ幾つかの欠点がある。例えば、フィードバック制御サンプリング回路は演算増幅器を必要とし、スイッチは開閉動作をすることが求められ、回路の配置はより複雑なものとなり、全体のコストは増加する。さらには、サンプリングとトリガーのための基準電圧はランプの最小動作電圧よりも低いため、サンプリング間隔(△T)の幅は比較的に広くなってしまう。このような状況において、図５に示されるように、サンプリング間隔(△T)の間にもいくらかの漏れ電流成分がまだ存在し、このため最大電流値のサンプリングの正確度が低下してしまう。 The lamp drive system described above still has some drawbacks. For example, the feedback control sampling circuit requires an operational amplifier, the switch is required to open and close, the circuit arrangement becomes more complicated, and the overall cost increases. Furthermore, since the reference voltage for sampling and triggering is lower than the minimum operating voltage of the lamp, the width of the sampling interval (ΔT) becomes relatively wide. In such a situation, as shown in FIG. 5, some leakage current components still exist during the sampling interval (ΔT), and the accuracy of sampling of the maximum current value is lowered.

このような、従来技術に存在する欠点を克服するために、冷陰極蛍光ランプを駆動するためのランプ駆動システムを提供する必要がある。 In order to overcome such disadvantages existing in the prior art, it is necessary to provide a lamp driving system for driving a cold cathode fluorescent lamp.

本発明の目的は、ランプ駆動システムを提供することである。ランプ駆動システムは第一の駆動モジュールを含む。第一の駆動モジュールは、複数の受動要素と検出点を含む第一の電流検出回路をもつ。検出点の電圧はランプの端子電流と正比例するため、本発明によるランプ駆動システムはランプの輝度を正確に、安定的に制御することができる。 An object of the present invention is to provide a lamp driving system. The lamp drive system includes a first drive module. The first drive module has a first current detection circuit including a plurality of passive elements and detection points. Since the voltage at the detection point is directly proportional to the terminal current of the lamp, the lamp driving system according to the present invention can control the brightness of the lamp accurately and stably.

請求項１に記載の本発明では、ランプを駆動するためのランプ駆動システムが提供される。ランプ駆動システムは、第一の駆動モジュールを含む。第一の駆動モジュールは第一の変圧器、第一のキャパシターと第一の電流検出回路を含む。第一の変圧器は第一の一次側と第一の二次側をもつ。第一の二次側は第一の端子と第二の端子がある。第一の二次側の第一の端子はランプの第一の側に接続される。第一のキャパシターは一端を、第一の変圧器の第一の二次側の第一の端子と、ランプとに接続されている。第一の電流検出回路は、複数の受動要素を含む。第一の電流検出回路の一端は、第一の変圧器の第一の二次側の第二の端子接続されている。第一の電流検出回路の他の一端は第一のキャパシターの他の一端に接続されている。第一の電流検出回路は第一の電圧を検出するための第一の検出点をもち、その第一の電圧はランプの容量性の電流成分を含まないランプ端子電流と正比例の関係にある。 According to the first aspect of the present invention, a lamp driving system for driving a lamp is provided. The lamp drive system includes a first drive module. The first drive module includes a first transformer, a first capacitor, and a first current detection circuit. The first transformer has a first primary side and a first secondary side. The first secondary side has a first terminal and a second terminal. The first terminal on the first secondary side is connected to the first side of the lamp. One end of the first capacitor is connected to the first terminal on the first secondary side of the first transformer and the lamp. The first current detection circuit includes a plurality of passive elements. One end of the first current detection circuit is connected to the second terminal on the first secondary side of the first transformer. The other end of the first current detection circuit is connected to the other end of the first capacitor. The first current detection circuit has a first detection point for detecting the first voltage, and the first voltage is directly proportional to the lamp terminal current that does not include the capacitive current component of the lamp.

以上の本発明による内容は、以下に示す詳細な説明と関連図を吟味することにより、通常の当業者にとってはさらに明らかなものとなる。 The contents according to the present invention will become more apparent to those skilled in the art by examining the following detailed description and related drawings.

従来技術による冷陰極蛍光ランプ駆動システムを示す概略回路図である。1 is a schematic circuit diagram showing a cold cathode fluorescent lamp driving system according to the prior art. 図１による冷陰極蛍光ランプの高電圧側と低電圧側に流れる電流信号の関連を示すタイミング波形図である。FIG. 2 is a timing waveform diagram showing a relationship between current signals flowing on a high voltage side and a low voltage side of the cold cathode fluorescent lamp of FIG. 1. 従来技術による冷陰極蛍光ランプ駆動システムの他の例を示す概略回路図である。It is a schematic circuit diagram which shows the other example of the cold cathode fluorescent lamp drive system by a prior art. 図３で示された実効電流値サンプリング制御器の概略ブロック図である。FIG. 4 is a schematic block diagram of an effective current value sampling controller shown in FIG. 3. 図３による冷陰極蛍光ランプの高電圧側と低電圧側に流れる電流信号の関連を示すタイミング波形図である。FIG. 4 is a timing waveform diagram showing a relationship between current signals flowing on a high voltage side and a low voltage side of the cold cathode fluorescent lamp according to FIG. 本発明の第一の実施例によるランプ駆動システムを示す概略回路図である。1 is a schematic circuit diagram showing a lamp driving system according to a first embodiment of the present invention. 図６Ａによるランプ駆動システムの整流器と電圧分圧ユニットを示す概略回路図である。FIG. 6B is a schematic circuit diagram showing a rectifier and a voltage dividing unit of the lamp driving system according to FIG. 6A. 本発明の第二の実施例によるランプ駆動システムを示す概略回路図である。It is a schematic circuit diagram which shows the lamp drive system by the 2nd Example of this invention. 図７Ａによるランプ駆動システムの整流器と電圧分圧ユニットを示す概略回路図である。7B is a schematic circuit diagram showing a rectifier and a voltage dividing unit of the lamp driving system according to FIG. 7A. FIG.

以下の実施例を参照することにより、本発明をさらに明確に説明する。ここで、次に説明される本発明の好ましい実施例は図示と説明のみを目的とすることに留意すべきである。本発明は、以下の詳細に記述した開示例で全てが示されるものではなく、またそれに限定されるものでもない。 The invention will be more clearly described by reference to the following examples. It should be noted here that the preferred embodiments of the invention described below are for illustration and description only. The present invention is not intended to be exhaustive or limited to the disclosure examples set forth in detail below.

図６Ａは、本発明の第一の実施例によるランプ駆動システムを示す概略回路図である。ランプ駆動システム３は、ランプ３７を駆動するために使われる。ランプ３７の例としては、冷陰極蛍光ランプがあるが、それに限るものではない。ランプ３７は直管形ランプまたはＵ形のランプである。ランプ駆動システム３は、基本的に第一の駆動モジュールで構成される。第一の駆動モジュールは第一の変圧器３４、第一のキャパシターＣ１、そして第一の電流検出回路３８とから成る。 FIG. 6A is a schematic circuit diagram showing a lamp driving system according to a first embodiment of the present invention. The lamp driving system 3 is used for driving the lamp 37. An example of the lamp 37 is a cold cathode fluorescent lamp, but is not limited thereto. The lamp 37 is a straight tube lamp or a U-shaped lamp. The lamp drive system 3 is basically composed of a first drive module. The first drive module includes a first transformer 34, a first capacitor C 1, and a first current detection circuit 38.

第一の変圧器３４は、第一の一次側と第一の二次側を備える。第一の二次側には第一の端子と第二の端子とがある。第一の二次側の第一の端子はランプ３７の第一の側に接続されている。ランプ３７の第二の側は接地されている。第一の変圧器３４の第一の二次側の第一の端子は第一の位相を持つＡＣ電圧を供給するために使われる。第一のキャパシターＣ１は共振キャパシターである。第一のキャパシターＣ１の一端は、第一の二次側の第一の端子とランプ３７に接続されている。第一の電流検出回路３８は、複数の受動要素を含む。第一の電流検出回路３８の一端は第一の変圧器３４の第一の二次側の第二の端子に接続されている。第一の電流検出回路３８の他の一端は、第一のキャパシターＣ１の他の一端に接続されている。第一の電流検出回路３８は第一の電圧Vsen1 を検出するための第一の検出点をもち、第一の電圧Vsen1はランプ３７の容量性電流成分を含まないランプ端子電流 i_L と正比例の関係にある。 The first transformer 34 includes a first primary side and a first secondary side. There is a first terminal and a second terminal on the first secondary side. The first terminal on the first secondary side is connected to the first side of the lamp 37. The second side of the lamp 37 is grounded. The first terminal on the first secondary side of the first transformer 34 is used to supply an AC voltage having a first phase. The first capacitor C1 is a resonant capacitor. One end of the first capacitor C1 is connected to the first terminal on the first secondary side and the lamp 37. The first current detection circuit 38 includes a plurality of passive elements. One end of the first current detection circuit 38 is connected to the second terminal on the first secondary side of the first transformer 34. The other end of the first current detection circuit 38 is connected to the other end of the first capacitor C1. The first current detection circuit 38 has a first detection point for detecting the first voltage Vsen1, and the first voltage Vsen1 is directly proportional to the lamp terminal current i _L not including the capacitive current component of the lamp 37. There is a relationship.

第一の電流検出回路３８は、第一の抵抗器Ｒ１と、第二の抵抗器Ｒ２と、第一の差電圧分圧器３８１とを含む。第一の変圧器３４の第一の二次側の第二の端子は第一の抵抗器Ｒ１を通して接地されている。第一のキャパシターＣ１の他の一端は、第二の抵抗器Ｒ２を通して接地されている。第一の差電圧分圧器３８１の一端は、第一の変圧器３４の第一の二次側の第二の端子と第一の抵抗器Ｒ１を接続する第一のノードに接続されている。第一の差電圧分圧器３８１の他の一端は、第一のキャパシターＣ１の他の一端と第二の抵抗器Ｒ２を接続する第二のノードに接続されている。 The first current detection circuit 38 includes a first resistor R1, a second resistor R2, and a first differential voltage divider 381. The second terminal on the first secondary side of the first transformer 34 is grounded through the first resistor R1. The other end of the first capacitor C1 is grounded through the second resistor R2. One end of the first differential voltage divider 381 is connected to a first node that connects the first secondary terminal of the first transformer 34 and the first resistor R1. The other end of the first differential voltage divider 381 is connected to a second node connecting the other end of the first capacitor C1 and the second resistor R2.

第一の差電圧分圧器３８１は、第三の抵抗器Ｒ３と、第四の抵抗器Ｒ４とを含む。第三の抵抗器Ｒ３の一端は第一のノードに接続されている。第四の抵抗器Ｒ４の一端は第二のノードに接続されている。第三の抵抗器Ｒ３の他の一端と第四の抵抗器Ｒ４の他の一端は、第一の検出点に接続されている。 The first differential voltage divider 381 includes a third resistor R3 and a fourth resistor R4. One end of the third resistor R3 is connected to the first node. One end of the fourth resistor R4 is connected to the second node. The other end of the third resistor R3 and the other end of the fourth resistor R4 are connected to the first detection point.

これより、第一の電圧Vsen1 はランプ３７の容量性電流成分を含まないランプ端子電流i_Lと正比例の関係にあること、すなわち等価抵抗器R_Lに流れる電流成分のみが残されていることの理由を、図６Ａを参照しながら、さらに詳しく論じる。 As a result, the first voltage Vsen1 is directly proportional to the lamp terminal current i _L not including the capacitive current component of the lamp 37, that is, only the current component flowing through the equivalent resistor R _L is left. The reason will be discussed in more detail with reference to FIG. 6A.

本実施例では、第三の抵抗器Ｒ３の抵抗値ｒ３は、第四の抵抗器Ｒ４の抵抗値ｒ４と近似的に等しいものとする。抵抗値ｒ３と抵抗値ｒ４とは、第一の抵抗器Ｒ１の抵抗値ｒ１と第二の抵抗器Ｒ２の抵抗値ｒ２に比べてかなり大きな値をとる。図６Ａに示すように、電流i_C1 は、第一のキャパシターＣ１と第二の抵抗器Ｒ２を通って流れる。漂遊電流i_C2 は、ランプ３７の等価的な漂遊キャパシターＣ２を通って流れる。この二つの電流i_C1 と i_C2 は、温度変化にともなって変化する。第一の抵抗器Ｒ１を通って逆向きに流れる電流は、電流 i_C1 と i_C2 と i_Lの和に等しい。電流 i_C1と電流 i_C2 は同位相であるから、第一の電圧Vsen1 は、抵抗値ｒ１と抵抗値ｒ２を調整することにより、ランプ３７のランプ端子電流 i_L と正比例の関係とすることができる。 In this embodiment, the resistance value r3 of the third resistor R3 is approximately equal to the resistance value r4 of the fourth resistor R4. The resistance value r3 and the resistance value r4 are considerably larger than the resistance value r1 of the first resistor R1 and the resistance value r2 of the second resistor R2. As shown in FIG. 6A, the current i _C1 flows through the first capacitor C1 and the second resistor R2. The stray current i _C2 flows through the equivalent stray capacitor _C2 of the lamp 37. These two currents i _C1 and i _C2 change as the temperature changes. The current flowing in the reverse direction through the first resistor R1 is equal to the sum of the currents i _C1 , i _C2 and i _L. Since the current i _C1 and the current i _C2 have the same phase, the first voltage Vsen1 can be directly proportional to the lamp terminal current i _L of the lamp 37 by adjusting the resistance value r1 and the resistance value r2. it can.

換言すれば、第一の抵抗器Ｒ１の抵抗値ｒ１は（６）式により定義され、第一の電圧Vsen1
は（７）式で定義される。第一の抵抗器Ｒ１の抵抗値ｒ１と第二の抵抗器Ｒ２の抵抗値ｒ２を適切に調整することにより、第一の電圧Vsen1 は、第一の抵抗器Ｒ１の抵抗値ｒ１とランプ端子電流 i_L
とに単なる正比例関係とすることができる。 In other words, the resistance value r1 of the first resistor R1 is defined by the equation (6), and the first voltage Vsen1
Is defined by equation (7). By appropriately adjusting the resistance value r1 of the first resistor R1 and the resistance value r2 of the second resistor R2, the first voltage Vsen1 becomes the resistance value r1 of the first resistor R1 and the lamp terminal current. i _L
And can be a simple direct proportional relationship.

図６Ａを再度参照願いたい。ランプ駆動システム３は、さらに駆動回路３２を備える。駆動回路３２は第一の変圧器３４の第一の一次側に接続されている。駆動回路３２により、ＤＣ電圧はＡＣ電圧に変換され、第一の変圧器３４の第一の一次側に伝達される。 Please refer to FIG. 6A again. The lamp driving system 3 further includes a driving circuit 32. The drive circuit 32 is connected to the first primary side of the first transformer 34. The drive circuit 32 converts the DC voltage into an AC voltage and transmits it to the first primary side of the first transformer 34.

図６Ａを再度参照願いたい。ランプ駆動システム３は、さらに整流器と電圧分圧ユニット３５を備えて、第一の電圧Vsen1 を整流し、分圧して、第一の電圧信号V_d1 を生成する。図６Ｂは、図６Ａで示されたランプ駆動システムの整流器と電圧分圧ユニットを図示する概略回路図である。図６Ｂで示されるように、整流器と電圧分圧ユニット３５は、ダイオードＤと電圧分圧器３５１とを含む。電圧分圧器３５１は、第五の抵抗器Ｒａと、第六の抵抗器Ｒｂと、平滑キャパシターＣｆとを含む。第一の電圧Vsen1 は、ダイオードＤによって連続的に整流され、平滑キャパシターＣｆにより平滑され、直列接続されたＲａとＲｂにより電圧分圧され、そして第一の電圧信号V_d1 を生成する。ダイオードＤのアノードは第一の検出点に接続される。ダイオードＤのカソードは、第五の抵抗器Ｒａの一端に接続される。第五の抵抗器Ｒａの他の一端は、第六の抵抗器Ｒｂの一端に接続される。第六の抵抗器Ｒｂの他の一端は、接地されている。第一の電圧信号V_d1 は、第五の抵抗器Ｒａと第六の抵抗器Ｒｂの間のノードから出力される。 Please refer to FIG. 6A again. Lamp driving system 3 further comprises a rectifier and voltage dividing unit 35, a first voltage Vsen1 rectified, divide, generating a first voltage signal V _d1. FIG. 6B is a schematic circuit diagram illustrating the rectifier and voltage dividing unit of the lamp driving system shown in FIG. 6A. As shown in FIG. 6B, the rectifier and voltage divider unit 35 includes a diode D and a voltage divider 351. The voltage divider 351 includes a fifth resistor Ra, a sixth resistor Rb, and a smoothing capacitor Cf. The first voltage Vsen1 is continuously rectified by the diode D, smoothed by the smoothing capacitor Cf, voltage-divided by Ra and Rb connected in series, and a first voltage signal _Vd1 is generated. The anode of the diode D is connected to the first detection point. The cathode of the diode D is connected to one end of the fifth resistor Ra. The other end of the fifth resistor Ra is connected to one end of the sixth resistor Rb. The other end of the sixth resistor Rb is grounded. The first voltage signal V _d1 is output from a node between the fifth resistor Ra and the sixth resistor Rb.

図６Ａを再度参照願いたい。ランプ駆動システム３は、さらにパルス幅変換制御器３６を備える。パルス幅変換制御器３６の一端は、整流器と電圧分圧ユニット３５に接続され、第一の電圧信号V_d1 を受信する。パルス幅変換制御器３６の他の一端は、駆動回路３２に接続される。第一の電圧信号V_d1 をパルス幅変換制御器３６に記憶されている基準電圧と比較することにより、パルス幅変換制御器３６は駆動回路３２に対して制御信号を発する。この制御信号に応じて、駆動回路３２のデューティサイクルが調整され、ランプ３７の輝度が安定的に制御される。 Please refer to FIG. 6A again. The lamp driving system 3 further includes a pulse width conversion controller 36. One end of the pulse width conversion controller 36 is connected to the rectifier and the voltage dividing unit 35 and receives the first voltage signal _Vd1 . The other end of the pulse width conversion controller 36 is connected to the drive circuit 32. By comparing the first voltage signal V _d1 with the reference voltage stored in the pulse width conversion controller 36, the pulse width conversion controller 36 issues a control signal to the drive circuit 32. In response to this control signal, the duty cycle of the drive circuit 32 is adjusted, and the brightness of the lamp 37 is stably controlled.

図７Ａは、本発明の第二の実施例によるランプ駆動システムを図示する概略回路図である。ランプ駆動システム４は、第一の駆動モジュールと第二の駆動モジュールとから成る。第一の駆動モジュールは、ランプ３７の第一の側に接続される。第一の駆動モジュールは第一の変圧器３４、第一のキャパシターＣ１と、第一の電流検出回路３８とを備える。第一の駆動モジュールの構成と動作原理は、第一の実施例で示されたものと同じであり、ここでは冗長に説明はしない。 FIG. 7A is a schematic circuit diagram illustrating a lamp driving system according to a second embodiment of the present invention. The lamp driving system 4 includes a first driving module and a second driving module. The first drive module is connected to the first side of the lamp 37. The first drive module includes a first transformer 34, a first capacitor C 1, and a first current detection circuit 38. The configuration and operating principle of the first drive module are the same as those shown in the first embodiment, and are not redundantly described here.

第二の駆動モジュールは、ランプ３７の第二の側に接続される。第二の駆動モジュールは、第二の変圧器４４と、第二のキャパシターＣ３と、第二の電流検出回路４８とを備える。 The second drive module is connected to the second side of the lamp 37. The second drive module includes a second transformer 44, a second capacitor C3, and a second current detection circuit 48.

第二の変圧器４４は、第二の一次側と第二の二次側とをもつ。第二の二次側には第三の端子と第四の端子とがある。第二の二次側の第三の端子は、ランプ３７の第二の側に接続される。第一の変圧器３４の第一の二次側の第一の端子は、第一の位相をもつＡＣ電圧を供給するために使われる。第二の変圧器４４の第二の二次側の第三の端子は、第二の位相をもつＡＣ電圧を供給するために使われる。ここに、第一の位相と第二の位相の位相差は１８０度である。第一の端子が正の高電圧の時は、第三の端子は負の高電圧となる。一方、第一の端子が負の高電圧の時は、第三の端子は正の高電圧となる。第二のキャパシターＣ３は共振用キャパシターである。第二のキャパシターＣ３の一端は、第二の二次側の第三の端子とランプ３７に接続される。 The second transformer 44 has a second primary side and a second secondary side. There is a third terminal and a fourth terminal on the second secondary side. The second terminal on the second secondary side is connected to the second side of the lamp 37. The first terminal on the first secondary side of the first transformer 34 is used to supply an AC voltage having a first phase. A third terminal on the second secondary side of the second transformer 44 is used to supply an AC voltage having a second phase. Here, the phase difference between the first phase and the second phase is 180 degrees. When the first terminal is a positive high voltage, the third terminal is a negative high voltage. On the other hand, when the first terminal has a negative high voltage, the third terminal has a positive high voltage. The second capacitor C3 is a resonance capacitor. One end of the second capacitor C3 is connected to the second terminal on the second secondary side and the lamp 37.

第二の電流検出回路４８は、複数の受動要素を含む。第二の電流検出回路４８の一端は、第二の変圧器４４の第二の二次側の第四の端子に接続される。第二の電流検出回路４８の他の一端は、第二のキャパシターＣ３の他の一端に接続される。第二の電流検出回路４８は、第二の検出点をもち、第二の電圧Vsen2 を検出する。第二の電圧Vsen2 は、ランプ３７の容量性電流成分を含まないランプ端子電流i_Lと正比例の関係にある。 The second current detection circuit 48 includes a plurality of passive elements. One end of the second current detection circuit 48 is connected to the fourth terminal on the second secondary side of the second transformer 44. The other end of the second current detection circuit 48 is connected to the other end of the second capacitor C3. The second current detection circuit 48 has a second detection point and detects the second voltage Vsen2. The second voltage Vsen2 is directly proportional to the lamp terminal current i _L not including the capacitive current component of the lamp 37.

第二の電流検出回路４８は、第七の抵抗器Ｒ７、第八の抵抗器Ｒ８と、第二の差電圧分圧器４８１とを含む。第二の変圧器４４の第二の二次側の第四の端子は、第七の抵抗器Ｒ７を通して接地される。第二のキャパシターＣ３の他の一端は、第八の抵抗器Ｒ８を通して接地される。第二の差電圧分圧器４８１の一端は、第二の変圧器４４の第二の二次側の第四の端子と第七の抵抗器Ｒ７を接続する第三のノードに接続される。第二の差電圧分圧器４８１の他の一端は、第二のキャパシターＣ３の他の一端と第八の抵抗器Ｒ８を接続する第四のノードに接続される。 The second current detection circuit 48 includes a seventh resistor R7, an eighth resistor R8, and a second differential voltage divider 481. The fourth terminal on the second secondary side of the second transformer 44 is grounded through the seventh resistor R7. The other end of the second capacitor C3 is grounded through an eighth resistor R8. One end of the second differential voltage divider 481 is connected to a third node connecting the fourth terminal on the second secondary side of the second transformer 44 and the seventh resistor R7. The other end of the second differential voltage divider 481 is connected to a fourth node connecting the other end of the second capacitor C3 and the eighth resistor R8.

第二の差電圧分圧器４８１は、第九の抵抗器Ｒ９と第十の抵抗器Ｒ１０を含む。第九の抵抗器Ｒ９の一端は、第三のノードに接続される。第十の抵抗器Ｒ１０の一端は、第四のノードに接続される。第九の抵抗器Ｒ９の他の一端と、第十の抵抗器Ｒ１０の他の一端は第二の検出点に接続される。第九の抵抗器Ｒ９の抵抗値は、第十の抵抗器Ｒ１０の抵抗値と近似的に等しい。第九の抵抗器Ｒ９と第十の抵抗器Ｒ１０の抵抗値は、第七の抵抗器Ｒ７と第八の抵抗器Ｒ８の抵抗値よりもかなり大きな値となる。 The second differential voltage divider 481 includes a ninth resistor R9 and a tenth resistor R10. One end of the ninth resistor R9 is connected to the third node. One end of the tenth resistor R10 is connected to the fourth node. The other end of the ninth resistor R9 and the other end of the tenth resistor R10 are connected to the second detection point. The resistance value of the ninth resistor R9 is approximately equal to the resistance value of the tenth resistor R10. The resistance values of the ninth resistor R9 and the tenth resistor R10 are considerably larger than the resistance values of the seventh resistor R7 and the eighth resistor R8.

図７Ａを再度参照願いたい。ランプ駆動システム４は、さらに整流器と電圧分圧ユニット４５を備え、第一の電圧Vsen1 と第二の電圧Vsen2 を整流、平滑し、分圧して第二の電圧信号V_d2 を生成する。図７Ｂは、図７Ａのランプ駆動システムの整流器と電圧分圧ユニットを示す概略回路図である。図７Ｂに示されるように、整流器と電圧分圧ユニット４５は、二つのダイオードＤ１とＤ２と、電圧分圧器４５１とを含む。電圧分圧器４５１は、第五の抵抗器Ｒａと第六の抵抗器Ｒｂと平滑キャパシターＣｆとを含む。第一の電圧Vsen1 と第二の電圧Vsen2 は、ダイオードＤ１とＤ２とによりそれぞれ整流され、平滑キャパシターＣｆにより平滑され、そして第二の電圧信号V_d2 は、第五の抵抗器Ｒａと第六の抵抗器Ｒｂの間のノードから出力される。ここに、ダイオードＤ１とＤ２と平滑キャパシターＣｆは第五の抵抗器Ｒａの一端に接続され、第五の抵抗器Ｒａの他の一端は第六の抵抗器Ｒｂの一端に接続され、第六の抵抗器Ｒｂの他の一端は接地されている。 Please refer to FIG. 7A again. Lamp driver system 4 further comprises a rectifier and voltage dividing unit 45, rectifying a first voltage Vsen1 the second voltage Vsen2, smoothed, to generate a second voltage signal V _d2 by dividing. FIG. 7B is a schematic circuit diagram showing a rectifier and a voltage dividing unit of the lamp driving system of FIG. 7A. As shown in FIG. 7B, the rectifier and voltage divider unit 45 includes two diodes D1 and D2 and a voltage divider 451. The voltage divider 451 includes a fifth resistor Ra, a sixth resistor Rb, and a smoothing capacitor Cf. A first voltage Vsen1 second voltage Vsen2 are respectively rectified by a diode D1 and D2, are smoothed by the smoothing capacitor Cf, and the second voltage signal V _d2 is fifth resistor Ra and the sixth Output from a node between resistors Rb. Here, the diodes D1 and D2 and the smoothing capacitor Cf are connected to one end of the fifth resistor Ra, and the other end of the fifth resistor Ra is connected to one end of the sixth resistor Rb. The other end of the resistor Rb is grounded.

図７Ａを再度参照願いたい。ランプ駆動システム４は、さらにパルス幅変換制御器４６を含む。パルス幅変換制御器４６の一端は、整流器と電圧分圧ユニット４５に接続され、第二の電圧信号V_d2を受信する。パルス幅変換制御器４６の他の一端は、駆動回路３２に接続される。第二の電圧信号V_d2を、パルス幅変換制御器４６に記憶されている基準電圧V_ref
と比較することにより、パルス幅変換制御器４６は、第一の変圧器３４と第二の変圧器４４とに接続された駆動回路３２に制御信号を発する。この制御信号により、駆動回路３２のデューティーサイクルは調整されて、ランプ３７の輝度を安定的に制御する。 Please refer to FIG. 7A again. The lamp driving system 4 further includes a pulse width conversion controller 46. One end of the pulse width conversion controller 46 is connected to the rectifier and the voltage dividing unit 45, and receives the second voltage signal _Vd2 . The other end of the pulse width conversion controller 46 is connected to the drive circuit 32. The second voltage signal V _d2 is converted into a reference voltage V _ref stored in the pulse width conversion controller 46.
, The pulse width conversion controller 46 issues a control signal to the drive circuit 32 connected to the first transformer 34 and the second transformer 44. By this control signal, the duty cycle of the drive circuit 32 is adjusted, and the luminance of the lamp 37 is stably controlled.

以上の説明により、本発明によるランプ駆動システムは少なくとも一つの駆動モジュールを含む。その駆動モジュールは複数の受動要素と一つの検出点を含む電流検出回路を備える。その検出点の電圧は、ランプのランプ端子電流と正比例関係にあるため、本発明によるランプ駆動システムは正確にかつ安定的にランプの輝度を制御することができる。さらに、電流検出回路は複数の受動要素から成るため、電流検出回路を非常に単純でコストの掛からないものとすることができる。 As described above, the lamp driving system according to the present invention includes at least one driving module. The drive module includes a current detection circuit including a plurality of passive elements and one detection point. Since the voltage at the detection point is directly proportional to the lamp terminal current of the lamp, the lamp driving system according to the present invention can control the brightness of the lamp accurately and stably. Furthermore, since the current detection circuit comprises a plurality of passive elements, the current detection circuit can be made very simple and inexpensive.

本発明は、現時点で最も実用的で最適な実施例は何かとの観点から説明されている。このため、本発明はここに開示された実施例に限定される必要はないと理解されるべきである。逆に、本発明は添付した請求項の精神や範囲の中に含まれる様々な変形や類似の構成にも範囲が及ぶことを意図しており、その請求項はそのような全ての変形や類似構成をも包含するような最も広い解釈が付与されるべきである。 The present invention has been described in terms of what is currently the most practical and optimal embodiment. Thus, it should be understood that the invention need not be limited to the embodiments disclosed herein. On the contrary, the invention is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims, and the claims are intended to cover all such modifications and similarities. The broadest interpretation should also be given, including the construction.

３ランプ駆動システム
４ランプ駆動システム
１２駆動回路
１４変圧器
１９冷陰極蛍光ランプ
２０インバーター
２２駆動回路
２４変圧器
２６パルス幅変換制御器
２７スイッチ
２８実効電流値サンプリング制御器
２９冷陰極蛍光ランプ
３２駆動回路
３４第一の変圧器
３５電圧分圧ユニット
３６パルス幅変換制御器
３７ランプ
３８第一の電流検出回路
４４第二の変圧器
４５電圧分圧ユニット
４６パルス幅変換制御器
４８第二の電流検出回路
２８２電圧分圧器
２８４ピーク電圧検出回路
３５１電圧分圧器
３８１第一の差電圧分圧器
４５１電圧分圧器
４８１第二の差電圧分圧器 3 Lamp Drive System 4 Lamp Drive System 12 Drive Circuit 14 Transformer 19 Cold Cathode Fluorescent Lamp 20 Inverter 22 Drive Circuit 24 Transformer 26 Pulse Width Conversion Controller 27 Switch 28 Effective Current Sampling Controller 29 Cold Cathode Fluorescent Lamp 32 Drive Circuit 34 First transformer 35 Voltage division unit 36 Pulse width conversion controller 37 Lamp 38 First current detection circuit 44 Second transformer 45 Voltage division unit 46 Pulse width conversion controller 48 Second current detection circuit 282 Voltage divider 284 Peak voltage detection circuit 351 Voltage divider 381 First differential voltage divider 451 Voltage divider 481 Second differential voltage divider

Claims

In a lamp driving system for driving a lamp,
The lamp driving system includes a first driving module, and the first driving module includes:
A first transformer having a first primary side and a first secondary side, the first secondary side having a first terminal and a second terminal, the first secondary side; The first terminal on the side connected to the first side of the lamp;
A first capacitor having one end connected to the first terminal and the lamp on the first secondary side of the first transformer;
A first current detection circuit including a plurality of passive elements, wherein one end of the first current detection circuit is connected to the second terminal on the first secondary side of the first transformer; The other end of the first current detection circuit is connected to the other end of the first capacitor, the first current detection circuit has a first detection point for detecting a first voltage, and The lamp driving system according to claim 1, wherein the first voltage is in direct proportion to the lamp terminal current i _L not including the capacitive current component of the lamp.

The lamp driving system according to claim 1, wherein the lamp is a cold cathode fluorescent lamp, and the first capacitor is a resonant capacitor.

The first current detection circuit includes a first resistor, a second resistor, and a first differential voltage divider, the first secondary side of the first transformer. Two terminals are grounded through the first resistor, the other end of the first capacitor is grounded through the second resistor, and one end of the first differential voltage divider is connected to the first resistor. Connected to a first node connecting the second terminal on the first secondary side of the transformer and the first resistor, the other end of the first differential voltage divider is The lamp driving system according to claim 1, wherein the lamp driving system is connected to a second node connecting the other end of the first capacitor and the second resistor.

The first differential voltage divider includes a third resistor and a fourth resistor, one end of the third resistor is connected to the first node, and one end of the fourth resistor Is connected to the second node, the other end of the third resistor and the other end of the fourth resistor are connected to the first detection point,
Here, the third resistance value of the third resistor is approximately equal to the fourth resistance value of the fourth resistor, and the third resistance value and the fourth resistance value are the first resistance value. The lamp driving system according to claim 3, wherein the lamp driving system has a value that is considerably larger than a first resistance value of the second resistor and a second resistance value of the second resistor.

The lamp further includes an equivalent stray capacitor, the first resistance value r1 of the first resistor, the second resistance value r2 of the second resistor, and the first capacitor value. The capacitance value c1 and the capacitance value c2 of the equivalent stray capacitor are expressed by the equation
According the the first voltage VSEN 1, wherein the lamp terminal current i the first resistance r1 of the _L and the first resistor formula
The lamp drive system according to claim 4, characterized in that

A drive circuit connected to the first primary side of the first transformer, the drive circuit converting a DC voltage to an AC voltage, the AC voltage being the first voltage of the first transformer; The lamp drive system according to claim 1, wherein the lamp drive system is transmitted to a primary side of the lamp.

A rectifier and a voltage dividing unit for rectifying and dividing the first voltage, and generating a first voltage signal, wherein the rectifier and the voltage dividing unit include a diode and a voltage divider; The voltage divider includes a fifth resistor, a sixth resistor, and a smoothing capacitor,
The first voltage is continuously rectified by the diode, smoothed by a smoothing capacitor, divided by the voltage divider, and generates the first voltage signal;
Here, the anode side of the diode is connected to the first detection point, the cathode side of the diode is connected to one end of the fifth resistor and one end of the smoothing capacitor, and the other end of the smoothing capacitor. Is grounded, the other end of the fifth resistor is connected to one end of the sixth resistor, the other end of the sixth resistor is grounded, and the first voltage signal is The lamp driving system according to claim 6, wherein the lamp driving system is output from a node between a fifth resistor and the sixth resistor.

A pulse width conversion controller, wherein one end of the pulse width conversion controller is connected to the rectifier and a voltage dividing unit to receive the first voltage signal, and the other end of the pulse width conversion controller is the The pulse width conversion controller is connected to the drive circuit, and the control circuit issues a control signal to the drive circuit by comparing the first voltage signal with a reference voltage, and a duty cycle of the drive circuit is adjusted according to the control signal. 8. The lamp driving system according to claim 7, wherein the brightness of the lamp is controlled in this way.

A second drive module connected to the second side of the lamp, the second drive module comprising:
A second transformer having a second primary side and a second secondary side, the second secondary side having a third terminal and a fourth terminal; The third terminal on the secondary side is connected to the second side of the lamp;
A second capacitor having one end connected to the third terminal on the second secondary side of the second transformer and the second side of the lamp;
A second current detection circuit including a plurality of passive elements, wherein one end of the second current detection circuit is connected to the fourth terminal on the second secondary side of the second transformer; The other end of the second current detection circuit is connected to the other end of the second capacitor, and the second current detection circuit has a second detection point for detecting a second voltage, and The lamp driving system according to claim 6, wherein the second voltage has a voltage proportional to a lamp terminal current that does not include a capacitive current component of the lamp.

The first terminal on the first secondary side of the first transformer supplies an AC voltage having a first phase, and the second terminal on the second secondary side of the second transformer. The three terminals supply an AC voltage having a second phase, wherein a phase difference between the first phase and the second phase is 180 degrees. Lamp drive system.

The first terminal is a positive high voltage terminal and the third terminal is a negative high voltage terminal, or the first terminal is a negative high voltage terminal and the third terminal is positive The lamp driving system according to claim 9, wherein the lamp driving system is a high voltage terminal.

The second current detection circuit includes a seventh resistor, an eighth resistor, and a second differential voltage divider, and the fourth terminal on the second secondary side of the second transformer. Is grounded through the seventh resistor, the other end of the second capacitor is grounded through the eighth resistor, and one end of the second differential voltage divider is connected to the second transformer. Connected to a third node connecting the fourth terminal on the second secondary side and the seventh resistor, and the other end of the second differential voltage divider is connected to the second node. The lamp driving system according to claim 9, wherein the lamp driving system is connected to a fourth node connecting the other end of the capacitor and the eighth resistor.

The second differential voltage divider includes a ninth resistor and a tenth resistor, one end of the ninth resistor is connected to the third node, and one end of the tenth resistor is Connected to the fourth node, the other end of the ninth resistor and the other end of the tenth resistor are connected to the second detection point,
Here, the resistance value of the ninth resistor is approximately equal to the resistance value of the tenth resistor, and the resistance values of the ninth resistor and the tenth resistor are the seventh resistance value. The lamp driving system according to claim 12, wherein the lamp driving system has a value considerably larger than resistance values of a resistor and the eighth resistor.

A rectifier and a voltage dividing unit for rectifying and dividing the first voltage and the second voltage are further generated to generate a second voltage signal, wherein the rectifier and the voltage dividing unit A first diode, a second diode and a voltage divider, the voltage divider including a fifth resistor, a sixth resistor and a smoothing capacitor, the first voltage and the second voltage divider. Are rectified by the first diode and the second diode, respectively, and smoothed by the smoothing capacitor, and the second voltage signal is between the fifth resistor and the sixth resistor. The lamp driving system according to claim 9, wherein the lamp driving system is output from a node.

A pulse width conversion controller; and one end of the pulse width conversion controller is connected to the rectifier and a voltage dividing unit to receive the second voltage signal, and the other end of the pulse width conversion controller is The pulse width conversion controller is connected to the driving circuit, and compares the second voltage signal with a reference voltage to transmit a control signal to the driving circuit, and the duty cycle of the driving circuit is set to the control signal. The lamp driving system according to claim 14, wherein the brightness of the lamp is controlled by being adjusted according to: