JP2008103470A - Led (light emitting diode) driving circuit - Google Patents

Led (light emitting diode) driving circuit Download PDF

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JP2008103470A
JP2008103470A JP2006283612A JP2006283612A JP2008103470A JP 2008103470 A JP2008103470 A JP 2008103470A JP 2006283612 A JP2006283612 A JP 2006283612A JP 2006283612 A JP2006283612 A JP 2006283612A JP 2008103470 A JP2008103470 A JP 2008103470A
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switching element
circuit
led
voltage
current
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Mitsuo Ohashi
光男 大橋
Iwao Sagara
岩男 相良
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Koa Corp
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Koa Corp
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Priority to JP2006283612A priority Critical patent/JP2008103470A/en
Priority to PCT/JP2007/070676 priority patent/WO2008050779A1/en
Priority to US12/442,830 priority patent/US8324816B2/en
Publication of JP2008103470A publication Critical patent/JP2008103470A/en
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Abstract

<P>PROBLEM TO BE SOLVED: To provide an economical LED driving circuit capable of increasing a power supply voltage Vcc beyond the impressable maximum voltage Vceo of a switching element in relation to the increase of number of LEDs connected in series. <P>SOLUTION: In the driving circuit, in which a multitude of LEDs are connected in series and which is equipped with the switching element for controlling the ON/OFF of the conducted current of the LED, a circuit element 15, such as a resistor or the like, is connected to the switching element 13 in parallel. Current I flows through the circuit element 15 connected in parallel to the switching element 13 when the switching element 13 is off. Although this current I is too small to cause the LED to turn on, it causes voltage drop in the LEDs 11 connected in series, and due to this voltage drop, an impressing voltage Vsw on the switching element 13 is reduced. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

本発明は、多数のＬＥＤを直列接続したＬＥＤ直列接続回路の通電電流をオン・オフし、多数のＬＥＤの一括点灯・消灯を行うＬＥＤ駆動回路に関する。   The present invention relates to an LED drive circuit that turns on / off an energization current of an LED series connection circuit in which a large number of LEDs are connected in series to turn on / off a large number of LEDs at once.

従来から、照明装置などにおいては、多数のＬＥＤを直列接続したＬＥＤ直列接続回路を複数列並列に接続し、その通電電流のオン・オフを駆動回路のスイッチング素子（トランジスタ）を用いて行い、多数のＬＥＤの点灯・消灯を一括制御することが行われている（例えば特許文献１、２、３、４）。
特開２００１−１５２７８号公報 特開２００３−１００４７２号公報 特開２００３−１３９７１２号公報 特開２００５−５０７０４号公報 2. Description of the Related Art Conventionally, in lighting devices and the like, LED series connection circuits in which a large number of LEDs are connected in series are connected in parallel in a plurality of rows, and the energization current is turned on / off using a switching element (transistor) of a drive circuit. The LED is turned on and off collectively (for example, Patent Documents 1, 2, 3, and 4).
JP 2001-15278 A Japanese Patent Laid-Open No. 2003-1000047 JP 2003-139712 A Japanese Patent Laying-Open No. 2005-50704

図６は、従来の一般的なＬＥＤ駆動回路の例である。直列に多数（ｎ個）のＬＥＤを接続してＬＥＤ直列接続回路１１を構成し、これに直流電源１２とスイッチング素子（トランジスタ）１３とを直列に接続する。スイッチング素子１３には制御回路１４が制御端子（ベース）に接続され、スイッチング素子１３をオン・オフ制御する制御信号が供給される。スイッチング素子１３にオン信号電圧が供給されると、スイッチング素子１３のコレクタ・エミッタ間はオン状態となり、電源１２から通電電流が流れ、多数のＬＥＤは一括で点灯する。スイッチング素子１３にオフ信号電圧が供給されると、スイッチング素子１３のコレクタ・エミッタ間はオフ状態となり、電源１２からの通電電流が遮断され、多数のＬＥＤ１３は一括で消灯する。   FIG. 6 is an example of a conventional general LED drive circuit. A large number (n) of LEDs are connected in series to form an LED series connection circuit 11, and a DC power supply 12 and a switching element (transistor) 13 are connected in series thereto. A control circuit 14 is connected to the control terminal (base) of the switching element 13 and supplied with a control signal for controlling on / off of the switching element 13. When the ON signal voltage is supplied to the switching element 13, the collector and the emitter of the switching element 13 are turned on, an energizing current flows from the power supply 12, and a large number of LEDs are turned on collectively. When the off signal voltage is supplied to the switching element 13, the collector-emitter between the switching element 13 is turned off, the energization current from the power source 12 is cut off, and a large number of LEDs 13 are turned off collectively.

従来のＬＥＤ駆動回路では、スイッチング素子１３がオフ状態の時に、直流電源１２の電源電圧Ｖccとほぼ同程度の電圧がスイッチング素子１３のコレクタ・エミッタ間に印加される。このため、より明るくする等の目的でＬＥＤの直列接続個数ｎを増加すると、「電源電圧Ｖcc＞ＬＥＤ数（ｎ）×ＬＥＤの順方向電圧（Ｖf）」、を満たす必要があるため、必要な電源電圧Ｖccが増加する。ここで、スイッチング素子へ印加可能な最大電圧Ｖceoが、
Ｖceo＜Ｖcc
という条件になるまで、電源電圧Ｖccを増加すると、通電電流がオフ時に、電源電圧Ｖccとほぼ同程度の電圧がスイッチング素子１３に印加され、スイッチング素子の印加可能最大電圧Ｖceoを超え、スイッチング素子１３が破壊するという問題がある。 In the conventional LED driving circuit, when the switching element 13 is in the OFF state, a voltage substantially equal to the power supply voltage Vcc of the DC power supply 12 is applied between the collector and the emitter of the switching element 13. For this reason, if the number n of LEDs connected in series is increased for the purpose of making it brighter or the like, it is necessary to satisfy “power supply voltage Vcc> number of LEDs (n) × LED forward voltage (Vf)”. The power supply voltage Vcc increases. Here, the maximum voltage Vceo that can be applied to the switching element is
Vceo <Vcc
When the power supply voltage Vcc is increased until the above condition is satisfied, when the energization current is turned off, a voltage substantially equal to the power supply voltage Vcc is applied to the switching element 13 and exceeds the maximum applicable voltage Vceo of the switching element. There is a problem of destroying.

本発明は、上述した事情に鑑みてなされたもので、直列接続するＬＥＤの数を増加し、これに関連して電源電圧Ｖccをスイッチング素子の印加可能最大電圧Ｖceo以上に増加することができる、経済的なＬＥＤ駆動回路を提供することを目的とする。   The present invention has been made in view of the above-described circumstances, and the number of LEDs connected in series can be increased, and in this connection, the power supply voltage Vcc can be increased to be higher than the maximum voltage Vceo that can be applied to the switching element. An object is to provide an economical LED driving circuit.

多数のＬＥＤを直列接続し、ＬＥＤの通電電流のオン・オフを制御するスイッチング素子を備えた駆動回路において、スイッチング素子に並列に抵抗器等の回路素子を接続したことを特徴とする。スイッチング素子に並列に接続した回路素子には、スイッチング素子のオフ時に電流Ｉが流れる。この電流ＩはＬＥＤが点灯しない程度の微少電流であるが、直列接続したＬＥＤに電位降下を生じさせ、この電位降下によりスイッチング素子への印加電圧が低減する。   In a drive circuit having a switching element that connects a large number of LEDs in series and controls on / off of the LED current, a circuit element such as a resistor is connected in parallel to the switching element. A current I flows through the circuit element connected in parallel to the switching element when the switching element is turned off. Although this current I is a very small current that does not light the LED, it causes a potential drop in the LEDs connected in series, and this potential drop reduces the voltage applied to the switching element.

本発明のＬＥＤ駆動回路では、スイッチング素子に並列に回路素子を追加接続したことにより、オフ時におけるスイッチング素子への印加電圧が低減するため、スイッチング素子の印加可能最大電圧Ｖceoよりも高い電源電圧ＶccをＬＥＤ駆動回路に印加することが可能になり、従来よりも多くのＬＥＤを直列接続して一括点灯することが可能となる。また、仮にＬＥＤ数が同じだった場合には、スイッチング素子に従来よりも最大印加可能電圧Ｖceoが低いスイッチング素子も選択可能となるため、スイッチング素子の選択肢が広がりコスト低減や回路性能向上等の効果が期待される。   In the LED drive circuit according to the present invention, the circuit element is additionally connected in parallel with the switching element, so that the voltage applied to the switching element at the time of OFF is reduced. Therefore, the power supply voltage Vcc higher than the maximum voltage Vceo that can be applied to the switching element. Can be applied to the LED drive circuit, and more LEDs can be connected in series than in the prior art to be turned on collectively. In addition, if the number of LEDs is the same, a switching element having a lower maximum applicable voltage Vceo can be selected as the switching element, so that options for the switching element are widened and effects such as cost reduction and circuit performance improvement are achieved. There is expected.

以下、本発明の実施形態について、添付図面を参照して説明する。なお、各図中、同一の機能を有する部材または要素には同一の符号を付して説明する。   Embodiments of the present invention will be described below with reference to the accompanying drawings. In addition, in each figure, the same code | symbol is attached | subjected and demonstrated to the member or element which has the same function.

図１は、本発明の一実施形態のＬＥＤ駆動回路を示し、図２は駆動対象のＬＥＤアレイを示す。図１に示すＬＥＤ駆動回路は、図２に示す多数のＬＥＤを直並列接続したＬＥＤアレイ１１に通電電流をオン・オフして、全ＬＥＤを一括して点灯／消灯する回路である。ＬＥＤアレイ１１は、例えば２０個のＬＥＤを直列接続したＬＥＤ直列接続回路を３０列並列接続し、合計６００個のＬＥＤを一括して点灯／消灯する２端子回路である。６００個のＬＥＤはマトリクス状に基板上に面状に配置され、面光源を構成している。なお、図１においては、ＬＥＤ直列接続回路の一列分のみを記載している。   FIG. 1 shows an LED drive circuit according to an embodiment of the present invention, and FIG. 2 shows an LED array to be driven. The LED drive circuit shown in FIG. 1 is a circuit that turns on / off all the LEDs in a lump by turning on and off the energization current to the LED array 11 in which a large number of LEDs shown in FIG. 2 are connected in series and parallel. The LED array 11 is a two-terminal circuit in which, for example, 30 columns of LED series connection circuits in which 20 LEDs are connected in series are connected in parallel, and a total of 600 LEDs are turned on / off collectively. The 600 LEDs are arranged in a matrix on a substrate in a planar shape to constitute a surface light source. In FIG. 1, only one row of LED series connection circuits is shown.

図２において、ＬＥＤの直列接続数を「ｎ」とし、並列接続数を「ｍ」とすると、「ｎ、ｍ」は「１、２、３、４・・・・」の様に任意の自然数でＬＥＤアレイを構成可能である。図２において、各ＬＥＤ直列接続回路中に、抵抗器を挿入することが好ましい。これにより、各ＬＥＤ直列接続回路のＬＥＤ順方向電圧Ｖｆにバラツキが存在しても、各ＬＥＤ直列接続回路にほぼ均等な通電電流を流すことができ、面光源としての輝度の均一性を確保することができる。   In FIG. 2, when the number of LEDs connected in series is “n” and the number of parallel connections is “m”, “n, m” is an arbitrary natural number such as “1, 2, 3, 4,... The LED array can be configured. In FIG. 2, it is preferable to insert a resistor in each LED series connection circuit. As a result, even if there is a variation in the LED forward voltage Vf of each LED series connection circuit, a substantially uniform energization current can be passed through each LED series connection circuit, and the uniformity of luminance as a surface light source is ensured. be able to.

ＬＥＤアレイ１１は、直流電源１２とスイッチング素子（トランジスタ）１３とに直列接続され、スイッチング素子１３がオン状態となると各ＬＥＤ直列接続回路にほぼ均等に通電電流が流れ、全ＬＥＤが点灯状態となり、スイッチング素子１３がオフ状態となると通電電流が遮断され、全ＬＥＤが消灯状態となる。制御回路１４は、輝度信号等の入力信号を受け、スイッチング素子１３のベース電極にオン信号電圧およびオフ信号電圧を供給する。このため、直流電源１２の電源電圧Ｖccは、一列分のｎ個のＬＥＤの点灯電圧（順方向電圧Ｖf×ｎ個）とスイッチング素子１３のオン電圧との合計電圧以上となることが必要である。   The LED array 11 is connected in series to a DC power source 12 and a switching element (transistor) 13. When the switching element 13 is turned on, an energization current flows through each LED series connection circuit almost evenly, and all LEDs are turned on. When the switching element 13 is turned off, the energization current is interrupted and all the LEDs are turned off. The control circuit 14 receives an input signal such as a luminance signal and supplies an on signal voltage and an off signal voltage to the base electrode of the switching element 13. For this reason, the power supply voltage Vcc of the DC power supply 12 needs to be equal to or higher than the total voltage of the lighting voltages (forward voltage Vf × n) of n LEDs for one column and the ON voltage of the switching element 13. .

ここで、スイッチング素子１３のエミッタに接続した電流設定用抵抗１６の抵抗値をＲとすると、スイッチング素子１３のエミッタ電流Ｉeは、電気回路の性質から、「 Ｉe＝（ＶBON−ＶBE）／Ｒ 」の関係が成り立つ。
但し、ＶBON＝オン信号電圧、
ＶBE＝スイッチング素子のベース・エミッタ間電圧
ＶBEはスイッチング素子の固有値であり、バイポーラトランジスタの場合約０．７〜１Ｖ程度であり、抵抗値Ｒは回路定数なので固定値とすると、エミッタ電流Ｉeはオン信号電圧ＶBONで制御可能となる。 Here, assuming that the resistance value of the current setting resistor 16 connected to the emitter of the switching element 13 is R, the emitter current Ie of the switching element 13 is “Ie = (V BON −V BE ) / R "relationship is established.
Where V BON = ON signal voltage,
V BE = Base-emitter voltage of the switching element V BE is an eigenvalue of the switching element. In the case of a bipolar transistor, it is about 0.7 to 1 V. Since the resistance value R is a circuit constant, the emitter current Ie Can be controlled by the ON signal voltage V BON .

本発明のＬＥＤ駆動回路においては、スイッチング素子１３と並列に追加の回路素子１５を接続している。この回路素子１５は、例えば抵抗器であるが、スイッチング素子１３のオフ時に回路素子１５に微少電流が流れ、スイッチング素子１３に印加される電圧を低減する。すなわち、ＬＥＤ駆動回路の出力段のスイッチング素子１３に対し、並列に抵抗器等の回路素子１５を挿入すると、スイッチング素子１３のオフ時には、ＬＥＤ直列接続回路１１と回路素子１５とが直列に接続され、微少電流Ｉが流れる。これにより、常に「微少電流Ｉ＞０」となるため、ＬＥＤ直列接続回路１１の各ＬＥＤの電圧Ｖを、「Ｖ＞０」とすることができ、スイッチング素子１３への印加電圧Ｖswを低減できる。   In the LED drive circuit of the present invention, an additional circuit element 15 is connected in parallel with the switching element 13. The circuit element 15 is, for example, a resistor, but a minute current flows through the circuit element 15 when the switching element 13 is turned off, and the voltage applied to the switching element 13 is reduced. That is, when a circuit element 15 such as a resistor is inserted in parallel with the switching element 13 at the output stage of the LED drive circuit, the LED series connection circuit 11 and the circuit element 15 are connected in series when the switching element 13 is turned off. A minute current I flows. Thereby, since “small current I> 0” is always obtained, the voltage V of each LED of the LED series connection circuit 11 can be set to “V> 0”, and the applied voltage Vsw to the switching element 13 can be reduced. .

すなわち、図３（日亜化学工業(株)の製品カタログより引用）に示すように、青色ＬＥＤの順電圧−順電流特性は、順電流が１ｍＡで順電圧が２．８Ｖ程度であり、μＡレベルの微少電流を流すことで、一段当たり２Ｖ程度の順方向電圧を形成できる。   That is, as shown in FIG. 3 (cited from the product catalog of Nichia Corporation), the forward voltage-forward current characteristics of the blue LED are as follows: forward current is 1 mA, forward voltage is about 2.8 V, and μA A forward voltage of about 2 V per stage can be formed by flowing a very small current.

本発明者等の実験によれば、青色ＬＥＤを２０個直列に接続し、回路素子１５として４７０ｋΩの抵抗器を用い、電源電圧Ｖccを８４Ｖとした場合、スイッチング素子１３がオフ時に、スイッチング素子１３への印加電圧Ｖswが３６Ｖであるという結果が得られた。この結果から、スイッチング素子１３のリーク電流をゼロとすれば（参考迄に製品カタログでは０．１μＡ以下）、回路素子１５に流れる電流Iは７６μＡ程度であり、ＬＥＤ直列接続回路の両端電圧は、４８Ｖであり、ＬＥＤ一段当たりの電圧は２．４Ｖ程度が形成されていることになる。   According to the experiments by the present inventors, when 20 blue LEDs are connected in series, a 470 kΩ resistor is used as the circuit element 15 and the power supply voltage Vcc is 84 V, the switching element 13 is turned off. As a result, the applied voltage Vsw was 36V. From this result, if the leakage current of the switching element 13 is zero (for reference, the product catalog is 0.1 μA or less), the current I flowing through the circuit element 15 is about 76 μA, and the voltage across the LED series connection circuit is 48V, and the voltage per LED is about 2.4V.

なお、スイッチング素子１３が定格電流でオン時には、スイッチング素子１３への印加電圧Ｖswが１４Ｖであった。この結果から、ＬＥＤ点灯時の順方向電圧はＬＥＤ一段当たり３．５Ｖであり、製品カタログのＶfのｔｙｐ値と一致した。   When the switching element 13 was turned on at the rated current, the applied voltage Vsw to the switching element 13 was 14V. From this result, the forward voltage when the LED was lit was 3.5 V per LED, which was consistent with the Vf type value of the product catalog.

従って、スイッチング素子１３の印加可能最大電圧Ｖceoは、回路素子１５を接続しない場合には電源電圧Ｖcc以上（８４Ｖ以上）が必要であったが、４７０ｋΩの抵抗器からなる回路素子１５を接続することで、これを３６Ｖに低減することができることが実験的に確かめられた。なお、並列に追加接続する回路素子１５に流れる電流で、ＬＥＤが点灯しないように、回路素子１５の抵抗値を設定する。回路素子１５に流れる電流はＬＥＤが点灯しない範囲で極力大きい程、ＬＥＤ直列接続回路部分の電圧分担分を大きくすることができ、スイッチング素子１３の印加可能最大電圧がより低いものの採用が可能である。   Therefore, when the circuit element 15 is not connected, the maximum voltage Vceo that can be applied to the switching element 13 needs to be equal to or higher than the power supply voltage Vcc (84 V or higher). However, the circuit element 15 including a 470 kΩ resistor is connected. It has been experimentally confirmed that this can be reduced to 36V. In addition, the resistance value of the circuit element 15 is set so that the LED does not light by the current flowing through the circuit element 15 additionally connected in parallel. As the current flowing through the circuit element 15 is as large as possible within the range in which the LED does not light, the voltage share of the LED series connection circuit portion can be increased, and the switching element 13 having a lower maximum applicable voltage can be employed. .

また、スイッチング素子１３の印加可能最大電圧Ｖceoを変更しなければ、回路素子１５を追加接続することにより、スイッチング素子１３への印加電圧Ｖswが低減するため、高い電源電圧Ｖccを印加可能になり、従来よりも多くのＬＥＤを直列接続し点灯することが可能となる。これにより、スイッチング素子の選択肢が広がりコスト低減や明るさ向上等の効果が期待される。   Further, if the maximum voltage Vceo that can be applied to the switching element 13 is not changed, the voltage Vsw applied to the switching element 13 is reduced by additionally connecting the circuit element 15, so that a high power supply voltage Vcc can be applied. It becomes possible to connect more LEDs than in the past and light them. As a result, the choices of switching elements are widened, and effects such as cost reduction and brightness improvement are expected.

回路素子１５の例としては、抵抗器に限らず、ＬＥＤ直列接続回路に微少電流を流せるものでよく、例えば定電圧ダイオード（ツェナーダイオード）を用いることができる。上記の実験例では、３６Ｖの降伏電圧を有するツェナーダイオードを用いることで、スイッチング素子１３への印加電圧Ｖswは３６Ｖ以上に上昇せず、スイッチング素子１３の印加可能最大電圧Ｖceoを３６Ｖ以上に低減することができる。   An example of the circuit element 15 is not limited to a resistor, but may be one that allows a minute current to flow in an LED series connection circuit. For example, a constant voltage diode (zener diode) can be used. In the above experimental example, by using a Zener diode having a breakdown voltage of 36V, the applied voltage Vsw to the switching element 13 does not rise to 36V or higher, and the maximum voltage Vceo that can be applied to the switching element 13 is reduced to 36V or higher. be able to.

同様に、回路素子１５としては、図４に示す定電流ダイオードを用いることができる。ＦＥＴのソース・ゲート電極を短絡することで定電流特性が得られる。また、図５に示す電圧制限回路を用いてもよい。この回路は、定電圧ダイオードとトランジスタとを組み合わせ、一定電圧でツェナーダイオードが降伏し、トランジスタがオン状態となり、そのトランジスタで電流を吸収するものである。この電圧制限回路によれば、定電圧ダイオード特性を有しつつ、ツェナーダイオードと比較して大きな電流容量を有するので、大容量のＬＥＤアレイ等の駆動回路に好適である。   Similarly, a constant current diode shown in FIG. 4 can be used as the circuit element 15. Constant current characteristics can be obtained by short-circuiting the source and gate electrodes of the FET. Further, a voltage limiting circuit shown in FIG. 5 may be used. In this circuit, a constant voltage diode and a transistor are combined, the Zener diode breaks down at a constant voltage, the transistor is turned on, and the transistor absorbs current. This voltage limiting circuit is suitable for a drive circuit such as a large-capacity LED array because it has a constant voltage diode characteristic and a larger current capacity than a Zener diode.

なお、上記実施形態ではスイッチング素子の例としてバイポーラトランジスタを用いる例について説明したが、ＭＯＳＦＥＴ等を用いることもできる。   In the above embodiment, an example in which a bipolar transistor is used as an example of the switching element has been described. However, a MOSFET or the like can also be used.

これまで本発明の一実施形態について説明したが、本発明は上述の実施形態に限定されず、その技術的思想の範囲内において種々異なる形態にて実施されてよいことは言うまでもない。   Although one embodiment of the present invention has been described so far, it is needless to say that the present invention is not limited to the above-described embodiment, and may be implemented in various forms within the scope of the technical idea.

本発明の一実施形態のＬＥＤ駆動回路の回路図である。It is a circuit diagram of the LED drive circuit of one Embodiment of this invention. ＬＥＤアレイの一例を示す回路図である。It is a circuit diagram which shows an example of an LED array. 青色ＬＥＤの順方向電圧−電流特性を示す図である。It is a figure which shows the forward direction voltage-current characteristic of blue LED. 定電流ダイオードの一例を示す図である。It is a figure which shows an example of a constant current diode. 電圧制限回路の一例を示す図である。It is a figure which shows an example of a voltage limiting circuit. 従来のＬＥＤ駆動回路の回路図である。It is a circuit diagram of the conventional LED drive circuit.

符号の説明Explanation of symbols

１１ ＬＥＤアレイ（ＬＥＤ直列接続回路）
１２ 直流電源
１３ スイッチング素子（トランジスタ）
１４ 制御回路
１５ 回路素子
１６ 電流設定用抵抗 11 LED array (LED series connection circuit)
12 DC power supply 13 Switching element (transistor)
14 Control circuit 15 Circuit element 16 Current setting resistor

Claims (6)

多数のＬＥＤを直列接続し、前記ＬＥＤの通電電流のオン・オフを制御するスイッチング素子を備えた駆動回路において、
前記スイッチング素子に並列に回路素子を接続したことを特徴とするＬＥＤ駆動回路。 In a drive circuit having a switching element that connects a large number of LEDs in series and controls on / off of the energization current of the LEDs,
An LED driving circuit comprising a circuit element connected in parallel to the switching element. 前記回路素子を、抵抗器としたことを特徴とする請求項１記載のＬＥＤ駆動回路。   The LED drive circuit according to claim 1, wherein the circuit element is a resistor. 前記回路素子を、定電圧ダイオードとしたことを特徴とする請求項１記載のＬＥＤ駆動回路。   The LED driving circuit according to claim 1, wherein the circuit element is a constant voltage diode. 前記回路素子を、定電流ダイオードとしたことを特徴とする請求項１記載のＬＥＤ駆動回路。   2. The LED driving circuit according to claim 1, wherein the circuit element is a constant current diode. 前記回路素子を、定電圧ダイオードとトランジスタとを組み合わせ、一定電圧以上で大きな電流容量を有する電圧制限回路としたことを特徴とする請求項１記載のＬＥＤ駆動回路。   2. The LED driving circuit according to claim 1, wherein the circuit element is a voltage limiting circuit having a large current capacity above a certain voltage by combining a constant voltage diode and a transistor. 順方向電圧ＶfのＬＥＤをｎ個直列接続し、前記ＬＥＤの通電電流をオン・オフ制御するスイッチング素子を備えた駆動回路において、
電源電圧Ｖccが、Ｖcc＞Ｖf×ｎである直流電源と、
前記スイッチング素子に並列に接続した回路素子と、
印加可能最大電圧Ｖceoが、Ｖceo＜Ｖccであるスイッチング素子と、
を備えたことを特徴とするＬＥＤ駆動回路。 In a drive circuit comprising n switching elements connected in series with a forward voltage Vf, and a switching element for controlling on / off of the current flowing through the LED,
A DC power supply with a power supply voltage Vcc of Vcc> Vf × n;
A circuit element connected in parallel to the switching element;
A switching element in which the maximum voltage Vceo that can be applied is Vceo <Vcc;
An LED driving circuit comprising:
JP2006283612A 2006-10-18 2006-10-18 Led (light emitting diode) driving circuit Pending JP2008103470A (en)

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JP2006283612A JP2008103470A (en) 2006-10-18 2006-10-18 Led (light emitting diode) driving circuit
PCT/JP2007/070676 WO2008050779A1 (en) 2006-10-18 2007-10-17 Led driving circuit
US12/442,830 US8324816B2 (en) 2006-10-18 2007-10-17 LED driving circuit

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JP2010016350A (en) * 2008-06-30 2010-01-21 Green Solution Technology Inc Transistor switch module, and light emitting diode drive circuit using the same
JP2011129286A (en) * 2009-12-16 2011-06-30 Hakubun:Kk Led bulb
TWI414209B (en) * 2009-12-30 2013-11-01 Au Optronics Corp Light emitting diode (led) driving circuit
JP2012018842A (en) * 2010-07-08 2012-01-26 Sharp Corp Led lighting device
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KR101839326B1 (en) * 2011-06-01 2018-03-16 엘지디스플레이 주식회사 Backlight unit and liquid crystal display device using the same
JP2013069578A (en) * 2011-09-22 2013-04-18 Panasonic Corp Light-emitting element lighting circuit and illumination device using the circuit
JP2013069572A (en) * 2011-09-22 2013-04-18 Panasonic Corp Light-emitting element lighting circuit and illumination device using the circuit
CN103687175A (en) * 2012-08-28 2014-03-26 朗捷科技股份有限公司 Linear LED drive circuit using capacitor series-parallel voltage reduction
CN103857100A (en) * 2012-11-29 2014-06-11 深圳市海洋王照明工程有限公司 Low-voltage power supply LED driving circuit and LED lamp fixture
KR101490231B1 (en) 2013-05-20 2015-02-10 주식회사 루멘스 LED illumination device for protecting switching circuit using current control
KR101553342B1 (en) 2013-05-20 2015-09-15 주식회사 루멘스 LED illumination device for protecting switching circuit using switching circuit current control
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