JP2009134933A - Led lighting device, and headlight for vehicle - Google Patents

Led lighting device, and headlight for vehicle Download PDF

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JP2009134933A
JP2009134933A JP2007308940A JP2007308940A JP2009134933A JP 2009134933 A JP2009134933 A JP 2009134933A JP 2007308940 A JP2007308940 A JP 2007308940A JP 2007308940 A JP2007308940 A JP 2007308940A JP 2009134933 A JP2009134933 A JP 2009134933A
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led
elements
circuit
constant current
lighting device
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JP2009134933A5 (en
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Takayoshi Nagai
孝佳 永井
Kikuo Izumi
喜久夫 泉
Takashi Osawa
孝 大澤
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Mitsubishi Electric Corp
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Abstract

<P>PROBLEM TO BE SOLVED: To achieve a compact LED lighting device which is individually adjustable for luminance of a plurality of LED elements and has a small range of color variations inexpensively. <P>SOLUTION: Switch elements Q1-Qn are respectively connected in parallel to a plurality of LED elements D1-Dn connected to each other in series, constant current is supplied from a constant current source 2 to the LED elements and series and parallel circuits of the switch elements, and luminance of the LED element can be individually controlled by performing ON/OFF of the switch element by a control circuit 1. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

この発明は、発光ダイオード（ＬＥＤ）素子で構成された半導体光源を点灯させるためのＬＥＤ点灯装置およびこのＬＥＤ点灯装置を使用した車両用前照灯に関するものである。   The present invention relates to an LED lighting device for lighting a semiconductor light source composed of a light emitting diode (LED) element, and a vehicle headlamp using the LED lighting device.

半導体光源としてのＬＥＤ（Light Emitting diode）素子は、車両用灯具、信号機および照明用灯具として広く用いられるようになっている。このようなＬＥＤ素子の輝度を調整する従来の方法として、ＬＥＤ素子に流れる電流値を制御したり、ＬＥＤ素子に流れる電流をＰＷＭ（Pulse Width Modulation)制御したりする方法があった。
ＰＷＭ制御によりＬＥＤ素子に対する通電と遮断を繰り返すことでＬＥＤ素子を減光点灯することができるが、例えば、全点灯時に定格電流が供給されることによって白色に発光していたものが、減光点灯時にＬＥＤ素子に供給する電流を少なくして平均電流を単に低下させると、ＬＥＤ素子の発光色のうち青色成分が徐々に低下し、ＬＥＤ素子が緑がかった色で発光することがある。このような半導体光源に色度変化が生じるのを防止するため、半導体光源に対する電流の供給をオンオフ制御信号に基づいて行なう場合、オンオフ制御信号のうち一方の論理レベルの時に半導体光源に規定の電流を供給し、オンオフ制御信号のうち他方の論理レベルの時には半導体光源に対する電流の供給を停止するようにした点灯制御回路がある。（例えば、特許文献１参照）。 An LED (Light Emitting Diode) element as a semiconductor light source is widely used as a vehicular lamp, a traffic light, and an illumination lamp. As a conventional method for adjusting the luminance of such an LED element, there is a method of controlling a current value flowing through the LED element or controlling a current flowing through the LED element by PWM (Pulse Width Modulation).
The LED element can be dimmed by repeating energization and shut-off of the LED element by PWM control. For example, the one that emits white light when the rated current is supplied during full lighting is dimmed. Sometimes, when the current supplied to the LED element is reduced to simply lower the average current, the blue component of the LED element's emission color gradually decreases, and the LED element emits light in a greenish color. In order to prevent such a chromaticity change from occurring in the semiconductor light source, when a current is supplied to the semiconductor light source based on the on / off control signal, a current stipulated in the semiconductor light source at one logic level of the on / off control signal. There is a lighting control circuit that stops the supply of current to the semiconductor light source when the other logic level of the on / off control signal is supplied. (For example, refer to Patent Document 1).

特開２００６−８６０６３号公報（段落番号［００２６］、図１）JP 2006-86063 A (paragraph number [0026], FIG. 1)

従来のＬＥＤ点灯装置は、以上のようにして輝度を調整していたが、複数のＬＥＤ素子の輝度を個別に調整する場合は、電流値またはパルス幅を調整可能な電源を、それぞれのＬＥＤ素子に個別に設ける必要があり、点灯回路が複雑でコストが高くなってしまうという問題があった。   The conventional LED lighting device has adjusted the brightness as described above. However, when individually adjusting the brightness of the plurality of LED elements, a power source capable of adjusting the current value or the pulse width is connected to each LED element. Therefore, there is a problem that the lighting circuit is complicated and the cost becomes high.

この発明は上記のような課題を解決するためになされたもので、小型、低コストで、かつ複数のＬＥＤ素子の輝度を個別に調整可能なＬＥＤ点灯装置を提供することを目的とするものである。   The present invention has been made to solve the above-described problems, and an object thereof is to provide an LED lighting device that is small in size, low in cost, and capable of individually adjusting the brightness of a plurality of LED elements. is there.

この発明に係るＬＥＤ点灯装置は、直列に接続された複数のＬＥＤ素子、このＬＥＤ素子の各々に並列に接続された複数のスイッチ素子、ＬＥＤ素子とスイッチ素子の直並列回路に定電流を供給する定電流源、およびスイッチ素子のオンオフを制御することによりＬＥＤ素子の輝度を制御する制御回路を備えたものである。   The LED lighting device according to the present invention supplies a constant current to a plurality of LED elements connected in series, a plurality of switch elements connected in parallel to each of the LED elements, and a series-parallel circuit of the LED elements and the switch elements. A constant current source and a control circuit for controlling the luminance of the LED element by controlling on / off of the switch element are provided.

また、この発明に係るＬＥＤ点灯装置は、直列に接続された複数のＬＥＤ素子により構成されるＬＥＤ素子群、このＬＥＤ素子群に並列に接続されたスイッチ素子、ＬＥＤ素子群とスイッチ素子の並列回路を複数組直列に接続したＬＥＤ素子回路網、このＬＥＤ素子回路網に定電流を供給する定電流源、およびスイッチ素子のオンオフを制御することによりＬＥＤ素子の輝度をＬＥＤ素子群毎に制御する制御回路を備えたものである。   The LED lighting device according to the present invention includes an LED element group composed of a plurality of LED elements connected in series, a switch element connected in parallel to the LED element group, and a parallel circuit of the LED element group and the switch element. LED element network connected in series, a constant current source for supplying a constant current to the LED element network, and control for controlling the brightness of the LED elements for each LED element group by controlling on / off of the switch elements A circuit is provided.

この発明によれば、直列に接続された複数のＬＥＤ素子の各々に並列に接続されたスイ
ッチ素子のオンオフ制御によりＬＥＤ素子の輝度を調整するとともに、ＬＥＤ素子とスイッチ素子の直並列回路に一括して定電流を供給する定電流源を設けたので、定電流源が一つで済み、点灯装置を小型でかつ低コストで実現できる。
また、ＬＥＤ素子の直列回路に一定電流を流すので、全てのＬＥＤ素子で電流が同じ値となり、ＬＥＤ素子間の色度ばらつきを減らすことができる。また、同一の輝度設定値に対するＬＥＤ素子間の輝度ばらつきを小さくすることができる。定電流源からはＬＥＤ素子１個分相当の電流を流せば良いので、電源回路での電力損失を低減することができる。 According to the present invention, the brightness of the LED element is adjusted by ON / OFF control of the switch element connected in parallel to each of the plurality of LED elements connected in series, and the LED element and the switch element are integrated in a series-parallel circuit. Since a constant current source for supplying a constant current is provided, only one constant current source is required, and the lighting device can be realized in a small size and at a low cost.
In addition, since a constant current is passed through the series circuit of LED elements, the current becomes the same value for all the LED elements, and chromaticity variation among the LED elements can be reduced. Moreover, the brightness dispersion | variation between LED elements with respect to the same brightness | luminance setting value can be made small. Since it is sufficient to flow a current corresponding to one LED element from the constant current source, power loss in the power supply circuit can be reduced.

実施の形態１．
以下、この発明の実施の形態１におけるＬＥＤ点灯装置を図に基づいて説明する。図１はこの発明の実施の形態１によるＬＥＤ点灯装置の回路構成図、図２はこの発明の実施の形態１における制御回路の構成を示す図、図３はこの発明の実施の形態１における定電流源の回路構成を示す図、図４はこの発明の実施の形態１における輝度調整動作を説明するためのタイミングチャートである。
図１において、ｎ個（ｎは２以上の自然数）のＬＥＤ素子Ｄ１〜Ｄｎが直列に接続されており、それぞれのＬＥＤ素子Ｄ１〜Ｄｎには並列にＦＥＴ（Field Effect Transistor
）などのスイッチ素子Ｑ１〜Ｑｎが並列に接続されている。すなわち、スイッチ素子Ｑ１のドレインがＬＥＤ素子Ｄ１のアノードと、スイッチ素子Ｑ１のソースがＬＥＤ素子Ｄ１のカソードと、いうように接続されている。 Embodiment 1 FIG.
Hereinafter, the LED lighting device in Embodiment 1 of this invention is demonstrated based on figures. 1 is a circuit configuration diagram of an LED lighting device according to Embodiment 1 of the present invention, FIG. 2 is a diagram illustrating a configuration of a control circuit according to Embodiment 1 of the present invention, and FIG. 3 is a constant configuration according to Embodiment 1 of the present invention. FIG. 4 is a timing chart for explaining the luminance adjustment operation in the first embodiment of the present invention.
In FIG. 1, n (n is a natural number of 2 or more) LED elements D1 to Dn are connected in series, and each LED element D1 to Dn is connected in parallel to an FET (Field Effect Transistor).
) And other switching elements Q1 to Qn are connected in parallel. That is, the drain of the switch element Q1 is connected to the anode of the LED element D1, and the source of the switch element Q1 is connected to the cathode of the LED element D1.

スイッチ素子Ｑ１〜Ｑｎの各ゲートには、スイッチ素子Ｑ１〜Ｑｎのオン／オフを制御する制御回路１が接続されている。この制御回路１の詳細については図２で説明する。複数のＬＥＤ素子Ｄ１〜Ｄｎとスイッチ素子Ｑ１〜Ｑｎの直並列回路にはＬＥＤ素子Ｄ１〜Ｄｎに定電流を供給するための定電流源２が接続されている。この定電流源２はＬＥＤ素子Ｄ１〜Ｄｎの直列回路に一定の電流Ｉ１を供給するＬＥＤ素子駆動用の電源である。この定電流源２の詳細については図３で説明する。 A control circuit 1 that controls ON / OFF of the switch elements Q1 to Qn is connected to each gate of the switch elements Q1 to Qn. Details of the control circuit 1 will be described with reference to FIG. A constant current source 2 for supplying a constant current to the LED elements D1 to Dn is connected to a series-parallel circuit of the plurality of LED elements D1 to Dn and the switch elements Q1 to Qn. The constant current source 2 is a power supply for LED element drive for supplying a constant current I 1 to the series circuit of the LED elements Dl to Dn. Details of the constant current source 2 will be described with reference to FIG.

次にこの発明の実施の形態１に使用される制御回路１について図２により説明する。図２において、制御回路１は、ＬＥＤ素子Ｄ１〜Ｄｎの点灯パターンを生成する点灯パターン生成回路１１と、スイッチ素子Ｑ１〜Ｑｎのゲートを駆動するゲート駆動回路１２とによって構成される。点灯パターン生成回路１１は、ＬＥＤ素子Ｄ１〜Ｄｎのオンオフや、発光デューティーを制御するためのタイミング信号を生成する回路であり、ＡＳＩＣやＦＰＧＡなどを用いたディジタル回路や、マイコンなどにより実現することができる。ゲート駆動回路１２は、ソース電位の互いに異なるＦＥＴなどのスイッチ素子Ｑ１〜Ｑｎのゲート駆動信号を与える必要があるが、レベルシフト回路１２ａと、バッファ回路１２ｂと、チャージポンプ回路１２ｃによって実現することができる。最も高い電位に接続されるスイッチ素子以外の全てのスイッチ素子Ｑ２〜Ｑｎを同時にオンする期間を定期的に設けることにより、チャージポンプ回路１２ｃのコンデンサＣ１〜Ｃｎに、ゲート駆動用の電荷を蓄積することが可能である。ゲート駆動回路１２は図２に示す構成のほか、それぞれのＦＥＴ毎に絶縁されたゲート電源とフォトカプラを用いることもできる。   Next, the control circuit 1 used in Embodiment 1 of the present invention will be described with reference to FIG. In FIG. 2, the control circuit 1 includes a lighting pattern generation circuit 11 that generates lighting patterns for the LED elements D1 to Dn, and a gate drive circuit 12 that drives the gates of the switch elements Q1 to Qn. The lighting pattern generation circuit 11 is a circuit that generates a timing signal for controlling the on / off of the LED elements D1 to Dn and the light emission duty, and can be realized by a digital circuit using an ASIC or FPGA, a microcomputer, or the like. it can. The gate drive circuit 12 needs to supply gate drive signals of switching elements Q1 to Qn such as FETs having different source potentials, and can be realized by the level shift circuit 12a, the buffer circuit 12b, and the charge pump circuit 12c. it can. By periodically providing a period during which all switch elements Q2 to Qn other than the switch element connected to the highest potential are simultaneously turned on, charges for driving the gate are accumulated in the capacitors C1 to Cn of the charge pump circuit 12c. It is possible. In addition to the configuration shown in FIG. 2, the gate drive circuit 12 can also use a gate power source and a photocoupler that are insulated for each FET.

次にこの発明の実施の形態１に使用される定電流源２について図３により説明する。図３において、定電流源２は、電圧源２１と定電流回路２２の組み合わせにより実現することができる。定電流回路２２の構成としては、降圧チョッパ型などのスイッチングコンバータを用いて構成される。定電流回路２２は、ＬＥＤ素子Ｄ１〜Ｄｎに流れる電流をＬＥＤ素子に直列に接続された検出抵抗Ｒsnsによって検出し、この検出電流に基づく検出電圧Ｖsenceを定電流制御回路２２ａに入力し、定電流制御回路２２ａからの制御信号によって電圧源２１とＬＥＤ素子Ｄ１との間に接続された電源用スイッチ素子Ｑｐのゲートを制御して、ＬＥＤ素子Ｄ１〜Ｄｎに流れる電流が一定になるようにする。
定電流回路２２は、ＬＥＤ素子Ｄ１〜Ｄｎのアノード側に接続することも、カソード側に接続することも可能である。 Next, the constant current source 2 used in Embodiment 1 of the present invention will be described with reference to FIG. In FIG. 3, the constant current source 2 can be realized by a combination of a voltage source 21 and a constant current circuit 22. The configuration of the constant current circuit 22 is configured using a switching converter such as a step-down chopper type. The constant current circuit 22 detects a current flowing through the LED elements D1 to Dn by a detection resistor Rsns connected in series with the LED elements, and inputs a detection voltage Vsence based on the detected current to the constant current control circuit 22a. The gate of the power switch element Qp connected between the voltage source 21 and the LED element D1 is controlled by a control signal from the control circuit 22a so that the current flowing through the LED elements D1 to Dn becomes constant.
The constant current circuit 22 can be connected to the anode side or the cathode side of the LED elements D1 to Dn.

次に図４を用いて、この発明の実施の形態１におけるＬＥＤ素子の輝度調整動作について、ＬＥＤ素子Ｄ１〜Ｄｎの数がｎ＝４の場合を例として説明する。
図４において、Ｑ１〜Ｑ４は、それぞれの同名のスイッチ素子Ｑ１〜スイッチ素子Ｑ４のＯＮ（導通）／ＯＦＦ（非導通）の状態を、また、Ｄ１〜Ｄ４は、それぞれの同名のＬＥＤ素子Ｄ１〜Ｄ４のＯＮ（発光）／ＯＦＦ（非発光）の状態を示すタイミングチャートである。なお以下ではＯＮ、ＯＦＦをオン、オフとして説明する。 Next, with reference to FIG. 4, the brightness adjustment operation of the LED elements in Embodiment 1 of the present invention will be described by taking the case where the number of LED elements D1 to Dn is n = 4 as an example.
In FIG. 4, Q1 to Q4 indicate the ON (conductive) / OFF (nonconductive) states of the switch elements Q1 to Q4 having the same names, and D1 to D4 indicate the LED elements D1 to D1 having the same names. It is a timing chart which shows the state of ON (light emission) / OFF (non-light emission) of D4. In the following description, ON and OFF are assumed to be on and off.

まず、ｔ０の時点にてスイッチ素子Ｑ１からスイッチ素子Ｑ４は全てオフとすると、ＬＥＤ素子Ｄ１〜Ｄ４には定電流源２から供給される所定の電流Ｉ１によって定電流駆動され，全てのＬＥＤ素子Ｄ１〜Ｄ４が同時に発光する。次に、ｔ１のタイミングにてスイッチ素子Ｑ１がオンすると、ＬＥＤ素子Ｄ１の両端はスイッチ素子Ｑ１によってショートされ、ＬＥＤ素子Ｄ１はオフとなる。このとき、それまでＬＥＤ素子Ｄ１を流れていた電流はスイッチ素子Ｑ１をバイパスして流れるため、ＬＥＤ素子Ｄ２〜Ｄ４はオンのままである。次に、ｔ２にてスイッチ素子Ｑ２がオンすると、ＬＥＤ素子Ｄ２がオフになる。以下、同様に他のＬＥＤ素子が順次オフする。このように、ＬＥＤ素子Ｄ１〜Ｄ４に並列に接続されたスイッチ素子Ｑ１〜Ｑ４をオン／オフ制御することにより、任意のＬＥＤ素子を、任意のタイミングでオン／オフすることができる。このとき、電流はＬＥＤ素子Ｄ１〜Ｄ４またはスイッチ素子Ｑ１〜Ｑ４の何れかを流れ続けるので、直列に接続された他のＬＥＤ素子とスイッチ素子の並列回路の動作に影響を与えることは無い。 First, when all the switching elements Q1 switching element Q4 is turned off at the time of t0, the LED element D1~D4 is constant current driven by a predetermined current I 1 supplied from the constant current source 2, all the LED elements D1 to D4 emit light simultaneously. Next, when the switch element Q1 is turned on at the timing t1, both ends of the LED element D1 are short-circuited by the switch element Q1, and the LED element D1 is turned off. At this time, the current that has been flowing through the LED element D1 flows by bypassing the switch element Q1, so that the LED elements D2 to D4 remain on. Next, when the switch element Q2 is turned on at t2, the LED element D2 is turned off. Thereafter, the other LED elements are sequentially turned off in the same manner. Thus, by turning on / off the switch elements Q1 to Q4 connected in parallel to the LED elements D1 to D4, any LED element can be turned on / off at an arbitrary timing. At this time, since the current continues to flow through any of the LED elements D1 to D4 or the switch elements Q1 to Q4, the operation of the parallel circuit of the other LED elements and the switch elements connected in series is not affected.

以上の動作を周期ＴＴ（周波数１／ＴＴ）にて繰り返すと、それぞれのＬＥＤ素子が所定のデューティーで発光する。例えば、ＬＥＤ素子Ｄ１の発光デューティーはＴ１／ＴＴとなる。ただし、Ｔ１はｔ０からｔ１までの時間である。同様に、ＬＥＤ素子Ｄ２の発光デューティーはＴ２／ＴＴ、ＬＥＤ素子Ｄ３の発光デューティーはＴ４／ＴＴ、ＬＥＤ素子Ｄ４の発光デューティーはＴ３／ＴＴとなる。ただし、Ｔ２はｔ０からｔ２までの時間、Ｔ３はｔ０からｔ３までの時間、Ｔ４はｔ０からｔ４までの時間である。
ここで、周波数１／ＴＴを人間の視覚における臨界融合周波数以上とすれば、ＬＥＤ素子の点滅は知覚されなくなり、それぞれの発光デューティーに比例した輝度で発光しているように見える。臨界融合周波数は、輝度や発光面積などの諸条件や、個人差等により異なるが、概ね３０Ｈｚから６０Ｈｚ程度である。ちらつきを感じさせないようにするには、周波数を６０Ｈｚ以上にするのが望ましい。 When the above operation is repeated at a cycle TT (frequency 1 / TT), each LED element emits light with a predetermined duty. For example, the light emission duty of the LED element D1 is T1 / TT. However, T1 is the time from t0 to t1. Similarly, the light emission duty of the LED element D2 is T2 / TT, the light emission duty of the LED element D3 is T4 / TT, and the light emission duty of the LED element D4 is T3 / TT. However, T2 is the time from t0 to t2, T3 is the time from t0 to t3, and T4 is the time from t0 to t4.
Here, if the frequency 1 / TT is set to be equal to or higher than the critical fusion frequency in human vision, the blinking of the LED element is not perceived, and it appears that light is emitted at a luminance proportional to each light emission duty. The critical fusion frequency varies depending on various conditions such as luminance and light emitting area, individual differences, and the like, but is generally about 30 Hz to 60 Hz. In order not to feel flicker, it is desirable to set the frequency to 60 Hz or more.

さて、ＬＥＤ素子Ｄ１〜Ｄ４は、電流値によって色度が変化（色シフト）する特性を有しており、色度の変化を抑制するためには、電流を一定としてパルス幅で輝度を調整することが望ましい。この発明においては、全てのＬＥＤ素子Ｄ１〜Ｄ４を同一の一定電流で駆動しつつ、それぞれのＬＥＤ素子Ｄ１〜Ｄ４に流れる電流パルスの幅を制御することにより輝度調整を行うので、色シフトが少なくなり、ＬＥＤ素子Ｄ１〜Ｄ４間の色度の差を小さくすることができる。また、同一の輝度設定値に対するＬＥＤ素子Ｄ１〜Ｄ４間の輝度ばらつきを小さくすることができる。
また、ＬＥＤ素子Ｄ１〜Ｄ４に並列に設けたスイッチ素子Ｑ１〜Ｑ４は、高速にターンオン／ターンオフすることが出来るので、ＬＥＤ素子Ｄ１〜Ｄ４に流れる電流は立ち上がり／立下りの速い理想的な矩形波に近い電流を流すことができ、色シフトをさらに小さくすることができる。 The LED elements D1 to D4 have a characteristic that the chromaticity changes (color shift) depending on the current value. In order to suppress the change in chromaticity, the luminance is adjusted with the pulse width while keeping the current constant. It is desirable. In the present invention, brightness adjustment is performed by controlling the width of the current pulse flowing through each LED element D1 to D4 while driving all the LED elements D1 to D4 with the same constant current, so that there is little color shift. Thus, the chromaticity difference between the LED elements D1 to D4 can be reduced. Moreover, the brightness dispersion | variation between LED element D1-D4 with respect to the same brightness setting value can be made small.
Further, since the switch elements Q1 to Q4 provided in parallel with the LED elements D1 to D4 can be turned on / off at high speed, the current flowing through the LED elements D1 to D4 is an ideal rectangular wave with a fast rise / fall. Current can be passed, and the color shift can be further reduced.

また、複数のＬＥＤ素子Ｄ１〜Ｄ４に対して共通の定電流回路２２を用いるので、定電流回路２２の回路数を減らすことができ、駆動回路を小型かつ低コストにすることができる。
また、ＬＥＤ素子Ｄ１〜Ｄ４は比較的低電圧、大電流であるため、駆動回路の内部抵抗による電力損失の割合が大きくなり、効率が低下することがあるが、この発明によれば、輝度を個別に調整可能としつつも、ＬＥＤ素子Ｄ１〜Ｄ４は直列に接続されているので、複数のＬＥＤ素子Ｄ１〜Ｄ４に対して定電流源２からはＬＥＤ素子１個分相当の電流を流せば良く、電源回路の内部抵抗による電力損失を低減することができる。
なお、ここではスイッチ素子としてＦＥＴを用いたが、他にＩＧＢＴやバイポーラトランジスタを用いても良い。 Further, since the common constant current circuit 22 is used for the plurality of LED elements D1 to D4, the number of constant current circuits 22 can be reduced, and the drive circuit can be reduced in size and cost.
Further, since the LED elements D1 to D4 have a relatively low voltage and a large current, the ratio of power loss due to the internal resistance of the drive circuit may increase and the efficiency may decrease. Although the LED elements D1 to D4 are connected in series while being individually adjustable, a current corresponding to one LED element may be supplied from the constant current source 2 to the plurality of LED elements D1 to D4. The power loss due to the internal resistance of the power supply circuit can be reduced.
In addition, although FET was used as a switch element here, you may use IGBT and a bipolar transistor in addition.

また、図４に示した例においては、１周期間の最初に全てのＬＥＤ素子（ただし、完全オフ＝輝度ゼロのＬＥＤ素子を除く）を点灯させ、順次消灯させていくことにより、輝度の制御を行ったが、オンおよびオフのタイミングは、ＬＥＤ素子毎に任意のタイミングに設定することができる。例えば、最初に全てをオフとし、順次点灯させて最終的に最大の点灯数となるように制御しても良い。   In the example shown in FIG. 4, the brightness control is performed by turning on all the LED elements (except for the LED element with completely off = zero brightness) at the beginning of one cycle and turning them off sequentially. However, the on and off timings can be set arbitrarily for each LED element. For example, it may be controlled so that all are turned off first and then sequentially turned on to finally reach the maximum number of lighting.

実施の形態２．
次にこの発明の実施の形態２におけるＬＥＤ点灯装置を図に基づいて説明する。実施の形態２におけるＬＥＤ点灯装置の回路構成図および制御回路の構成を示す図は実施の形態１と同じである。この発明の実施の形態２においては定電流源を実施の形態１と異なる回路構成としたものである。
図５はこの発明の実施の形態２における定電流源の回路構成を示す図で、定電流源２は電圧源２１と定電流回路２３で構成され、定電流回路２３として、トランジスタの活性領域を用いたリニアレギュレータ型の定電流回路を用いたものである。図５に示すように、定電流回路２３は、ＬＥＤ素子Ｄ１〜Ｄｎに直列にトランジスタＴｒ１と検出抵抗Ｒsns
を接続し、検出抵抗Ｒsnsによって検出した電流に基づく検出電圧ＶsenceをトランジスタＴｒ２のベースに入力して制御することにより、ＬＥＤ素子Ｄ１〜Ｄｎに流れる電流が一定になるようにしたものである。このリニアレギュレータ型の定電流回路はよく知られているので、その動作説明は省略する。
なお定電流回路２３は、ＬＥＤ素子Ｄ１〜Ｄｎのアノード側に接続することも、カソード側に接続することも可能である。 Embodiment 2. FIG.
Next, the LED lighting device in Embodiment 2 of this invention is demonstrated based on figures. The circuit diagram of the LED lighting device and the diagram showing the configuration of the control circuit in the second embodiment are the same as those in the first embodiment. In the second embodiment of the present invention, the constant current source has a circuit configuration different from that of the first embodiment.
FIG. 5 is a diagram showing a circuit configuration of a constant current source according to Embodiment 2 of the present invention. The constant current source 2 includes a voltage source 21 and a constant current circuit 23. As the constant current circuit 23, an active region of a transistor is formed. The linear regulator type constant current circuit used is used. As shown in FIG. 5, the constant current circuit 23 includes a transistor Tr1 and a detection resistor Rsns in series with the LED elements D1 to Dn.
, And a detection voltage Vsence based on the current detected by the detection resistor Rsns is input to the base of the transistor Tr2 and controlled so that the current flowing through the LED elements D1 to Dn becomes constant. Since this linear regulator type constant current circuit is well known, its description is omitted.
The constant current circuit 23 can be connected to the anode side of the LED elements D1 to Dn or can be connected to the cathode side.

実施の形態３．
次にこの発明の実施の形態３におけるＬＥＤ点灯装置を図に基づいて説明する。
この発明においては、ＬＥＤ素子を点灯させるための電源として定電流源２を用いている。上述のように、定電流源２は電圧源と定電流回路を組み合わせて実現することが可能である。
ここで、定電流回路として、図５に示したようなリニアレギュレータ型の定電流回路２３を用いた場合、定電流回路における電力損失は、定電流回路２３に印加される電圧に比例して増大する。定電流回路に印加される電圧は、電圧源２１の出力電圧と、ＬＥＤ素子Ｄ１〜Ｄｎにおける電圧降下の合計との差である。電圧源２１の出力電圧を、ＬＥＤ素子Ｄ１〜Ｄｎにおける電圧降下に近づければ、定電流回路２３における電力損失を低減することができる。 Embodiment 3 FIG.
Next, the LED lighting device in Embodiment 3 of this invention is demonstrated based on figures.
In the present invention, the constant current source 2 is used as a power source for lighting the LED element. As described above, the constant current source 2 can be realized by combining a voltage source and a constant current circuit.
Here, when the linear regulator type constant current circuit 23 as shown in FIG. 5 is used as the constant current circuit, the power loss in the constant current circuit increases in proportion to the voltage applied to the constant current circuit 23. To do. The voltage applied to the constant current circuit is the difference between the output voltage of the voltage source 21 and the total voltage drop in the LED elements D1 to Dn. If the output voltage of the voltage source 21 is close to the voltage drop in the LED elements D1 to Dn, the power loss in the constant current circuit 23 can be reduced.

そこで、実施の形態３の発明においては、制御回路１により電圧源の出力電圧を制御することとし、ＬＥＤ素子の同時点灯数に応じて出力電圧を可変することにより、定電流回路２３における電力損失を低減するようにしたものである。
図６はこの発明の実施の形態３におけるＬＥＤ点灯装置の回路構成図、図７はこの発明の実施の形態３におけるＬＥＤ素子Ｄ１〜Ｄ４の点灯状態と可変電圧源の出力電圧との関係を示すタイミングチャートである。
図６において、定電流源はＬＥＤ素子Ｄ１〜Ｄｎに接続された可変電圧源２４と定電流回路２３とで構成されている。定電流回路２３は図５に示すような定電流回路である。可
変電圧源２４は制御回路１からの電圧制御信号Ｖcntによって出力電圧Ｖdcが可変するよ
うになっている。制御回路１はＬＥＤ素子Ｄ１〜Ｄｎに並列に接続されたスイッチ素子Ｑ１〜Ｑｎのオン／オフを制御すると共に、ＬＥＤ素子Ｄ１〜Ｄｎの点灯数に応じた電圧制御信号Ｖcntを出力するようになっている。そして制御回路１から出力される電圧制御信
号Ｖcntによって、可変電圧源２４の出力電圧Ｖdcを制御している。 Therefore, in the invention of the third embodiment, the control circuit 1 controls the output voltage of the voltage source, and the output voltage is varied according to the number of LED elements that are simultaneously turned on. It is intended to reduce this.
FIG. 6 is a circuit configuration diagram of the LED lighting device according to the third embodiment of the present invention, and FIG. 7 shows the relationship between the lighting state of the LED elements D1 to D4 and the output voltage of the variable voltage source according to the third embodiment of the present invention. It is a timing chart.
In FIG. 6, the constant current source includes a variable voltage source 24 and a constant current circuit 23 connected to the LED elements D1 to Dn. The constant current circuit 23 is a constant current circuit as shown in FIG. The variable voltage source 24 is configured such that the output voltage Vdc is variable by the voltage control signal Vcnt from the control circuit 1. The control circuit 1 controls on / off of the switch elements Q1 to Qn connected in parallel to the LED elements D1 to Dn, and outputs a voltage control signal Vcnt corresponding to the number of lighting of the LED elements D1 to Dn. ing. The output voltage Vdc of the variable voltage source 24 is controlled by the voltage control signal Vcnt output from the control circuit 1.

次に図７を用いて、この発明の実施の形態３におけるＬＥＤ素子の点灯パターンの一例と、そのときの可変電圧源２４の出力電圧Ｖdcとの関係について、ＬＥＤ素子Ｄ１〜Ｄｎの数がｎ＝４の場合を例として説明する。
図７において、Ｄ１〜Ｄ４は、それぞれ同名のＬＥＤ素子Ｄ１〜Ｄ４のオン（発光）／オフ（非発光）の状態を示し、ＶdcはＬＥＤ素子Ｄ１〜Ｄ４の点灯数に応じた可変電圧源２４の出力電圧を示すタイミングチャートである。
図７のｔ０からｔ１までの期間のＬＥＤ素子Ｄ１〜Ｄ４の同時点灯数は４であり、ｔ１からｔ２までの期間のＬＥＤ素子Ｄ１〜Ｄ４の同時点灯数は３、その後、同時点灯数は２、１、０と、同時点灯数は減少し、ｔ５で再び同時点灯数が４に戻る。 Next, with reference to FIG. 7, regarding the relationship between an example of the lighting pattern of the LED element in Embodiment 3 of the present invention and the output voltage Vdc of the variable voltage source 24 at that time, the number of LED elements D1 to Dn is n. = 4 will be described as an example.
In FIG. 7, D1 to D4 indicate on (light emission) / off (non-light emission) states of the LED elements D1 to D4 having the same names, respectively, and Vdc is a variable voltage source 24 corresponding to the number of lighting of the LED elements D1 to D4. It is a timing chart which shows the output voltage.
The number of simultaneous lighting of the LED elements D1 to D4 in the period from t0 to t1 in FIG. 7 is 4, the number of simultaneous lighting of the LED elements D1 to D4 in the period from t1 to t2 is 3, and then the number of simultaneous lighting is 2 1 and 0, the number of simultaneous lighting decreases, and the number of simultaneous lighting returns to 4 again at t5.

そこで、ＬＥＤ素子の同時点灯数が多いほど、可変電圧源２４の出力電圧Ｖdcが高くなるように制御する。好ましくは、定電流回路２３が正常に動作するために最小限印加する必要のある電圧をＶ０、ＬＥＤ素子の順方向電圧をＶｆ、ＬＥＤ素子の同時点灯数をｋとしたとき、電圧源の出力電圧Ｖdcが、
Ｖdc ＝ ｋ×Ｖｆ ＋Ｖ０
となるように制御する。 Therefore, the control is performed so that the output voltage Vdc of the variable voltage source 24 becomes higher as the number of simultaneously lighting LED elements increases. Preferably, when the voltage that needs to be applied at a minimum for the constant current circuit 23 to operate normally is V0, the forward voltage of the LED element is Vf, and the number of simultaneous lighting of the LED elements is k, the output of the voltage source The voltage Vdc is
Vdc = k × Vf + V0
Control to be

このように制御することにより、定電流回路２３に印加される電圧は、常に最小限の値となり、リニアレギュレータ型定電流回路を用いた場合は、定電流回路２３における電力損失が低減される。また、定電流回路２３として図３に示すような降圧チョッパ型定電流回路を用いた場合は、降圧チョッパの入力電圧と出力電圧の差が小さくなり、リップルを減少させることができる。
可変電圧源２４には、昇圧チョッパやフォワードコンバータなど、各種のスイッチングコンバータを用いることができる。スイッチングコンバータの応答速度は有限であり、電圧制御信号Ｖcntが入力されてから出力電圧Ｖdcが所定の値となるまでに遅れが生じるの
で、同時点灯数が変化するよりも遅れ時間分早く電圧制御信号Ｖcntを変化させても良い
。 By controlling in this way, the voltage applied to the constant current circuit 23 is always a minimum value, and when a linear regulator type constant current circuit is used, power loss in the constant current circuit 23 is reduced. Further, when the step-down chopper type constant current circuit as shown in FIG. 3 is used as the constant current circuit 23, the difference between the input voltage and the output voltage of the step-down chopper becomes small, and the ripple can be reduced.
As the variable voltage source 24, various switching converters such as a boost chopper and a forward converter can be used. Since the response speed of the switching converter is finite and a delay occurs until the output voltage Vdc reaches a predetermined value after the voltage control signal Vcnt is input, the voltage control signal is earlier than the number of simultaneous lighting changes. Vcnt may be changed.

実施の形態４．
次にこの発明の実施の形態４におけるＬＥＤ点灯装置を図に基づいて説明する。
実施の形態４おいては、電圧源としてＡＣ電源を入力としたものである。ＡＣ電源を入力とするＬＥＤ点灯装置は蛍光灯や電球を置き換えて、家庭や店舗などの照明に用いることができる。
ＡＣ電源を入力とする場合は、ＡＣ入力電流の高調波を低減し力率を改善するために、通常、電源入力段に力率改善回路を用いる必要がある。実施の形態４の発明においては、力率改善回路を実施の形態３で説明した図６の可変電圧源２４と兼用したもので説明する。
図８はこの発明の実施の形態４における回路構成図を示すもので、可変電圧源は、ＡＣ（交流）電源２４１と、このＡＣ電源２４１からの入力電圧を脈流の直流（ＤＣ）に変換するダイオードブリッジ回路２４２と、このダイオードブリッジ回路２４２の出力をＤＣ電圧に変換すると共に、力率を改善する力率改善回路２４３で構成されている。ＬＥＤ素子Ｄ１〜Ｄｎとスイッチ素子Ｑ１〜Ｑｎの直並列回路と力率改善回路２４３との間には定電流回路２３が接続される。その他の回路構成は図６と同様につき説明を省略する。 Embodiment 4 FIG.
Next, the LED lighting device in Embodiment 4 of this invention is demonstrated based on figures.
In the fourth embodiment, an AC power source is input as a voltage source. An LED lighting device using AC power as an input can be used for lighting in a home or a store by replacing a fluorescent lamp or a light bulb.
When an AC power supply is used as an input, it is usually necessary to use a power factor correction circuit in the power supply input stage in order to reduce harmonics of the AC input current and improve the power factor. In the invention of the fourth embodiment, the power factor correction circuit will be described using the variable voltage source 24 of FIG. 6 described in the third embodiment.
FIG. 8 shows a circuit configuration diagram according to the fourth embodiment of the present invention. The variable voltage source is an AC (alternating current) power source 241 and an input voltage from the AC power source 241 is converted into a pulsating direct current (DC). And a power factor improving circuit 243 for converting the output of the diode bridge circuit 242 into a DC voltage and improving the power factor. A constant current circuit 23 is connected between the series-parallel circuit of the LED elements D1 to Dn and the switch elements Q1 to Qn and the power factor correction circuit 243. Other circuit configurations are the same as those in FIG.

図８において、ＡＣ電源２４１から入力された交流電流はダイオードブリッジ回路２４２で正弦波状の脈流に変換された後、力率改善回路２４３によりＤＣ電圧に変換される。力率改善回路２４３は昇圧または降圧または昇降圧のコンバータにより構成されるが、ここでは昇圧チョッパ方式のコンバータを用いている。すなわち、力率改善回路２４３内のスイッチ素子Ｑｒをオンオフ制御することにより、ＡＣ電源の電圧ピークよりも高い直流電圧Ｖｄｃを得ている。ここで、ダイオードブリッジ回路２４２から昇圧チョッパ回路に流れ込む電流波形は、スイッチ素子Ｑｒのオンオフのタイミング（デューティなど）によって可変するので、スイッチ素子Ｑｒのオンオフを制御回路１からの制御電圧Ｖcntを用いて適切に制御することにより、入力電流波形を正弦波状かつ入力電圧波形と同相となるように制御することが可能となる。例えば、ダイオードブリッジ回路２４２の出力電圧（脈流波形）と力率改善回路２４３の入力電流とを検出し、両者が相似の波形となるようにフィードバック制御すれば良い。このようにして、入力電流波形を正弦波状かつ入力電圧波形と同相となるように制御すれば、ＡＣ電源２４１からの入力の力率が改善される。力率改善回路２４３の出力として得られるＤＣ電圧の出力は、定電流回路２３を介してＬＥＤ素子Ｄ１〜ＤｎとスイッチＱ１〜Ｑｎの直並列回路に印加される。ここで、力率改善回路２４３の出力電圧Ｖdcを、実施の形態３と同様にＬＥＤ素子Ｄ１〜Ｄｎの同時点灯数に応じて可変する。この構成によれば、可変電圧源２４を力率改善回路と兼用することにより、駆動回路を小型、低コストで実現することが可能となる。   In FIG. 8, the alternating current input from the AC power source 241 is converted into a sine wave pulsating current by the diode bridge circuit 242, and then converted to a DC voltage by the power factor correction circuit 243. The power factor correction circuit 243 is constituted by a step-up or step-down or step-up / step-down converter, and here, a step-up chopper type converter is used. That is, the DC voltage Vdc higher than the voltage peak of the AC power supply is obtained by on / off controlling the switching element Qr in the power factor correction circuit 243. Here, the current waveform flowing from the diode bridge circuit 242 into the boost chopper circuit varies depending on the ON / OFF timing (duty etc.) of the switch element Qr. By appropriately controlling, it is possible to control the input current waveform so that it is sinusoidal and in phase with the input voltage waveform. For example, the output voltage (pulsating current waveform) of the diode bridge circuit 242 and the input current of the power factor correction circuit 243 may be detected, and feedback control may be performed so that both have similar waveforms. In this way, if the input current waveform is controlled to have a sine wave shape and the same phase as the input voltage waveform, the power factor of the input from the AC power source 241 is improved. The output of the DC voltage obtained as the output of the power factor correction circuit 243 is applied to the series-parallel circuit of the LED elements D1 to Dn and the switches Q1 to Qn via the constant current circuit 23. Here, the output voltage Vdc of the power factor correction circuit 243 is varied in accordance with the number of LED elements D1 to Dn that are simultaneously turned on, as in the third embodiment. According to this configuration, by using the variable voltage source 24 also as a power factor correction circuit, the drive circuit can be realized in a small size and at a low cost.

実施の形態５．
次にこの発明の実施の形態５におけるＬＥＤ点灯装置を図に基づいて説明する。
実施の形態１においては、図４に示したように、１周期間の最初に全てのＬＥＤ素子Ｄ１〜Ｄｎを点灯させ、順次消灯させていくことにより、輝度の制御を行う方法を例として挙げた。
この場合、ＬＥＤ素子Ｄ１〜Ｄｎの直列回路に印加する電圧は、１周期間の最初に最大値、ｎ×Ｖｆとなる。ｎが大きい場合には、ＬＥＤ素子Ｄ１〜Ｄｎの直列回路に印加する最大電圧が非常に高くなるので、電圧源２１の最大出力電圧を高くする必要が生じる。
そこで、実施の形態５においては、ＬＥＤ素子Ｄ１〜Ｄｎの最大同時点灯数をｎよりも小さい所定の値に制限することとした。図９に、実施の形態５におけるＬＥＤ素子の点灯パターンの一例を示す。 Embodiment 5 FIG.
Next, an LED lighting device according to Embodiment 5 of the present invention will be described with reference to the drawings.
In the first embodiment, as shown in FIG. 4, as an example, a method of controlling brightness by turning on all LED elements D1 to Dn at the beginning of one period and sequentially turning them off is given. It was.
In this case, the voltage applied to the series circuit of the LED elements D1 to Dn becomes the maximum value, n × Vf, first in one period. When n is large, the maximum voltage applied to the series circuit of the LED elements D1 to Dn becomes very high, so that the maximum output voltage of the voltage source 21 needs to be increased.
Therefore, in the fifth embodiment, the maximum simultaneous lighting number of the LED elements D1 to Dn is limited to a predetermined value smaller than n. In FIG. 9, an example of the lighting pattern of the LED element in Embodiment 5 is shown.

図９に示すように、この例においては、ＬＥＤ素子Ｄ１〜Ｄｎの直列数ｎ＝４に対して、最大同時点灯数を３に制限している。すなわち、ｔ０からｔ１の期間においては、ＬＥＤ素子Ｄ１〜Ｄ３はＯＮ（オン）であり、すでに最大同時点灯数に達したため、ＬＥＤ素子Ｄ４は強制的にＯＦＦ（オフ）とする。ｔ１にてＬＥＤ素子Ｄ１がＯＦＦ（オフ）となった時点で、ＬＥＤ素子Ｄ４をＯＮ（オン）する。
以上のように制御することにより、電圧源２１の最大出力電圧を低減することができるので、電圧源２１の耐電圧を下げることができ、また、ピーク電力を低減することができるので、点灯回路をより低コストで実現することが可能となる。 As shown in FIG. 9, in this example, the maximum simultaneous lighting number is limited to 3 with respect to the serial number n = 4 of the LED elements D1 to Dn. That is, in the period from t0 to t1, the LED elements D1 to D3 are ON (on), and since the maximum number of simultaneous lighting has been reached, the LED element D4 is forcibly set to OFF (off). When the LED element D1 is turned off at t1, the LED element D4 is turned on.
By controlling as described above, the maximum output voltage of the voltage source 21 can be reduced, so that the withstand voltage of the voltage source 21 can be lowered and the peak power can be reduced. Can be realized at a lower cost.

実施の形態６．
この発明の実施の形態６における車両用前照灯を図に基づいて説明する。この実施の形態６の発明は、実施の形態１〜５で説明したＬＥＤ点灯装置のいずれか１つを用いて車両用前照灯を構成したものである。図１０はこの発明の実施の形態６における車両用前照灯（ヘッドライト）の概略構成図、図１１（ａ）（ｂ）は図１０に示す車両用前照灯に用いられるＬＥＤ素子モジュールの正面図と側面図である。
図１０および図１１において、複数のＬＥＤ素子Ｄｎが基板３１上にマトリクス状に並べられてＬＥＤ素子モジュール３２が構成されている。このＬＥＤ素子モジュール３２は前照灯ケース３３の背面側に設置され、前照灯ケース３３の前面側には複数のＬＥＤ素子Ｄｎから放射される光を、それぞれのＬＥＤ素子Ｄｎに対応して定められた方向に投射す
る光学ユニット３４が設けられている。ＬＥＤ素子モジュール３２にはＬＥＤ素子Ｄｎの各々を任意の輝度にて発光させる駆動回路３５が接続される。この駆動回路３５は実施の形態１〜５にて説明したＬＥＤ点灯装置のいずれかが用いられる。 Embodiment 6 FIG.
A vehicle headlamp according to Embodiment 6 of the present invention will be described with reference to the drawings. In the sixth embodiment, a vehicle headlamp is configured by using any one of the LED lighting devices described in the first to fifth embodiments. 10 is a schematic configuration diagram of a vehicle headlamp (headlight) according to Embodiment 6 of the present invention, and FIGS. 11A and 11B are diagrams of LED element modules used in the vehicle headlamp shown in FIG. It is a front view and a side view.
10 and 11, a plurality of LED elements Dn are arranged in a matrix on a substrate 31 to constitute an LED element module 32. The LED element module 32 is installed on the back side of the headlamp case 33, and light emitted from the plurality of LED elements Dn is determined on the front side of the headlamp case 33 corresponding to each LED element Dn. An optical unit 34 for projecting in the specified direction is provided. The LED element module 32 is connected to a drive circuit 35 that causes each of the LED elements Dn to emit light with an arbitrary luminance. Any of the LED lighting devices described in the first to fifth embodiments is used as the drive circuit 35.

この実施の形態６の車両用前照灯は、マトリクス状に並べられた複数のＬＥＤ素子Ｄｎを備えるＬＥＤ素子モジュール３２を用いており、それぞれのＬＥＤ素子Ｄｎから放射された光は光学ユニット３４によって、それぞれ定められた方向に投射される。また、複数のＬＥＤ素子Ｄｎを駆動回路３５によって駆動すれば、それぞれのＬＥＤ素子Ｄｎを任意の輝度で発光させることが可能となり、前照灯の配光分布を可変することができる。   The vehicle headlamp according to the sixth embodiment uses an LED element module 32 including a plurality of LED elements Dn arranged in a matrix, and light emitted from each LED element Dn is transmitted by an optical unit 34. , Respectively, in the determined direction. Further, if the plurality of LED elements Dn are driven by the drive circuit 35, each LED element Dn can emit light with an arbitrary luminance, and the light distribution of the headlamp can be varied.

さて、車両用前照灯において、ステアリングの操舵方向に光軸を向け、進行方向に集中的に光を照射することにより視認性を向上させるＡＦＳ（Adaptive Front-Lighting System）や、レベリング制御といった機能を有するものがある。従来はランプやＬＥＤ素子などの光源と、レンズなどによる光学系を組み込んだ前照灯ユニットの向きを、アクチュエータなどを用いて変化させて配光を変化させることによりこれらの機能を実現していた。
この実施の形態６の発明を用いれば、前照灯ユニットを機械的に動かすことなく、自由に配光分布を変更することができるので、ＡＦＳやレベリング制御などの機能を有する前照灯を、小型化、軽量化することができる。さらに、この発明によればＬＥＤ素子間の色度の差を小さくすることができるので、色ムラの少ない投射光を得ることができる。 Now, functions such as AFS (Adaptive Front-Lighting System) and leveling control that improve visibility by turning the optical axis in the steering direction of the steering and irradiating light intensively in the traveling direction in the vehicle headlamps Some have Conventionally, these functions were realized by changing the light distribution by changing the direction of the headlamp unit incorporating a light source such as a lamp or LED element and an optical system such as a lens using an actuator or the like. .
By using the invention of the sixth embodiment, the light distribution can be freely changed without mechanically moving the headlamp unit. Therefore, the headlamp having functions such as AFS and leveling control can be used. It can be reduced in size and weight. Furthermore, according to the present invention, the difference in chromaticity between the LED elements can be reduced, so that projection light with little color unevenness can be obtained.

実施の形態７．
次にこの発明の実施の形態７におけるＬＥＤ点灯装置を車両用前照灯に適用した場合について図に基づいて説明する。図１２はこの発明の実施の形態７におけるＬＥＤ点灯装置の回路構成を示す図である。
図１２において、複数のＬＥＤ素子が互いに直列に接続されてＬＥＤ素子群を構成し、それぞれのＬＥＤ素子群は、ハイビーム用ＬＥＤ素子群ＤＨ、ロービーム用ＬＥＤ素子群ＤＬ、およびＤＲＬ（Daylight Running Lights： 昼間点灯走行）用ＬＥＤ素子群ＤＲ、の３つのＬＥＤ素子群にブロック分けされている。複数のＬＥＤ素子が互いに直列に接続されて構成された各ＬＥＤ素子群ＤＨ、ＤＬ、ＤＲには並列にスイッチ素子Ｑ１〜Ｑ３が接続されている。３つのＬＥＤ素子群ＤＨ、ＤＬ、ＤＲとスイッチ素子Ｑ１〜Ｑ３の並列回路は、さらに直列に接続されてＬＥＤ素子回路網を構成し、このＬＥＤ素子回路網に一括して定電流源２から一定電流を供給している。スイッチ素子Ｑ１〜Ｑ３は制御回路１によりオン／オフ制御されるようになっている。 Embodiment 7 FIG.
Next, the case where the LED lighting device according to Embodiment 7 of the present invention is applied to a vehicle headlamp will be described with reference to the drawings. FIG. 12 is a diagram showing a circuit configuration of an LED lighting device according to Embodiment 7 of the present invention.
In FIG. 12, a plurality of LED elements are connected in series to form an LED element group. Each LED element group includes a high beam LED element group D H , a low beam LED element group D L , and a DRL (Daylight Running It is divided into three LED element groups: Lights: Daytime running) LED element group D R. Switching element Q1~Q3 are connected in parallel in each of a plurality of LED element groups D H which LED elements are formed by connecting in series with each other, D L, D R. Three LED element group D H, D L, D R and a parallel circuit of the switch element Q1~Q3 further constitute a LED element circuitry are connected in series, a constant current source collectively to the LED element network 2 is supplying a constant current. The switch elements Q1 to Q3 are controlled to be turned on / off by the control circuit 1.

ここで、スイッチ素子Ｑ１〜Ｑ３を制御回路１によりオン／オフ制御すれば、それぞれの群のＬＥＤ素子を任意の輝度で発光させることができる。例えば、昼間走行時には、ロービーム用ＬＥＤ素子群ＤＬとハイビーム用ＬＥＤ素子群ＤＨは、並列に接続されたスイッチ素子Ｑ１、Ｑ２をオンとすることにより、消灯状態とし、ＤＲＬ用ＬＥＤ素子群ＤＲに並列に接続されたスイッチ素子Ｑ３をＰＷＭ制御することにより、ＤＲＬ用ＬＥＤ素子群ＤＲを任意の輝度で発光させることができる。同様に、ロービーム用ＬＥＤ素子群ＤＬのみ、あるいはハイビーム用ＬＥＤ素子群ＤＨのみを任意の輝度で発光させることもできる。また、２つあるいは３つのＬＥＤ素子群を、それぞれ任意の輝度で同時に点灯させることも可能である。
この実施の形態７によれば、ハイビーム用ＬＥＤ素子群ＤＨとロービーム用ＬＥＤ素子群ＤＬとＤＲＬ用ＬＥＤ素子群ＤＲを、１つの電源回路のみで駆動することができるので、電源回路の小型化および低コスト化が可能となる。さらに、全てのＬＥＤ素子には一定かつ同一の電流を流すので、色シフトが小さくなり、色むらを防止することが可能となる。 Here, if the switch elements Q1 to Q3 are on / off controlled by the control circuit 1, the LED elements of each group can emit light with arbitrary luminance. For example, during daytime, the LED element group D L and the high-beam LED element group D H for low beam, by turning on the switch elements Q1, Q2 connected in parallel, and unlit, DRL for LED element group D the switching element Q3 connected in parallel to R by PWM control, it is possible to the LED element group D R for DRL light at any brightness. Similarly, it is also possible to emit light for low beam LED element group D L only, or only the high-beam LED element group D H in arbitrary luminance. It is also possible to light two or three LED element groups simultaneously with arbitrary luminance.
According to the seventh embodiment, the high-beam LED element group D H and the LED element group D L and the DRL LED element group D R for low beam, it is possible to drive only one of the power supply circuit, the power supply circuit Miniaturization and cost reduction are possible. Furthermore, since a constant and the same current is supplied to all the LED elements, the color shift is reduced and color unevenness can be prevented.

この発明の実施の形態１によるＬＥＤ点灯装置の回路構成図である。It is a circuit block diagram of the LED lighting device by Embodiment 1 of this invention. この発明の実施の形態１における制御回路の構成を示す図である。It is a figure which shows the structure of the control circuit in Embodiment 1 of this invention. この発明の実施の形態１における定電流源の回路構成を示す図である。It is a figure which shows the circuit structure of the constant current source in Embodiment 1 of this invention. この発明の実施の形態１における輝度調整動作を説明するためのタイミングチャートである。It is a timing chart for demonstrating the luminance adjustment operation | movement in Embodiment 1 of this invention. この発明の実施の形態２における定電流源の回路構成を示す図である。It is a figure which shows the circuit structure of the constant current source in Embodiment 2 of this invention. この発明の実施の形態３によるＬＥＤ点灯装置の回路構成図である。It is a circuit block diagram of the LED lighting device by Embodiment 3 of this invention. この発明の実施の形態３におけるＬＥＤ素子の点灯状態と出力電圧との関係を説明するためのタイミングチャートである。It is a timing chart for demonstrating the relationship between the lighting state of the LED element in Embodiment 3 of this invention, and an output voltage. この発明の実施の形態４によるＬＥＤ点灯装置の回路構成図である。It is a circuit block diagram of the LED lighting device by Embodiment 4 of this invention. この発明の実施の形態５における輝度調整動作を説明するためのタイミングチャートである。It is a timing chart for demonstrating the brightness adjustment operation | movement in Embodiment 5 of this invention. この発明の実施の形態６における車両用前照灯を示す概略構成図である。It is a schematic block diagram which shows the vehicle headlamp in Embodiment 6 of this invention. この発明の実施の形態６に使用されるＬＥＤ素子モジュールの正面図と側面図である。It is the front view and side view of an LED element module which are used for Embodiment 6 of this invention. この発明の実施の形態７によるＬＥＤ点灯装置の回路構成図である。It is a circuit block diagram of the LED lighting device by Embodiment 7 of this invention.

符号の説明Explanation of symbols

Ｄ１〜Ｄｎ：ＬＥＤ素子、 Ｑ１〜Ｑｎ：スイッチ素子、
１：制御回路、 ２：定電流源、
１１：点灯パターン生成回路、 １２：ゲート駆動回路、
１２ａ：レベルシフト回路、 １２ｂ：バッファ回路、
１２ｃ：チャージポンプ回路、 ２１：電圧源、
２２：定電流回路、 ２２ａ：定電流制御回路、
Ｒsns：検出抵抗 Ｑｐ：電源用スイッチ素子
２３：定電流回路、 ２４：可変電圧源、
３１：基板、 ３２：ＬＥＤ素子モジュール、
３３：前照灯ケース、 ３４：光学ユニット、
３５：駆動回路、 ２４１：ＡＣ電源、
２４２：ダイオードブリッジ回路、 ２４３：力率改善回路、
ＤＨ：ハイビーム用ＬＥＤ素子群 ＤＬ：ロービーム用ＬＥＤ素子群、
ＤＲ：ＤＲＬ用ＬＥＤ素子群。 D1 to Dn: LED elements, Q1 to Qn: switch elements,
1: control circuit, 2: constant current source,
11: lighting pattern generation circuit, 12: gate drive circuit,
12a: level shift circuit, 12b: buffer circuit,
12c: charge pump circuit, 21: voltage source,
22: constant current circuit, 22a: constant current control circuit,
Rsns: detection resistor Qp: power switch element 23: constant current circuit 24: variable voltage source
31: Substrate, 32: LED element module,
33: headlight case, 34: optical unit,
35: Drive circuit, 241: AC power supply,
242: Diode bridge circuit, 243: Power factor correction circuit,
D H : LED element group for high beam D L : LED element group for low beam,
D R : LED element group for DRL.

Claims (10)

直列に接続された複数のＬＥＤ素子、このＬＥＤ素子の各々に並列に接続された複数のスイッチ素子、前記ＬＥＤ素子とスイッチ素子の直並列回路に定電流を供給する定電流源、および前記スイッチ素子のオンオフを制御することにより前記ＬＥＤ素子の輝度を制御する制御回路を備えたＬＥＤ点灯装置。   A plurality of LED elements connected in series, a plurality of switch elements connected in parallel to each of the LED elements, a constant current source for supplying a constant current to a series-parallel circuit of the LED elements and the switch elements, and the switch elements The LED lighting device provided with the control circuit which controls the brightness | luminance of the said LED element by controlling ON / OFF of LED. 制御回路は、スイッチ素子のオンオフまたは発光デューティーを制御するためのタイミング信号を生成する点灯パターン生成回路と、前記スイッチ素子のゲートを駆動するゲート駆動回路とで構成された請求項１に記載のＬＥＤ点灯装置。   2. The LED according to claim 1, wherein the control circuit includes a lighting pattern generation circuit that generates a timing signal for controlling on / off of the switch element or a light emission duty, and a gate drive circuit that drives a gate of the switch element. Lighting device. 定電流源は、複数のＬＥＤ素子に電圧を供給する電圧源と、この電圧源により前記複数のＬＥＤ素子に流れる電流が一定になるよう制御する定電流回路とで構成された請求項１または請求項２に記載のＬＥＤ点灯装置。   The constant current source includes a voltage source that supplies a voltage to the plurality of LED elements, and a constant current circuit that controls the current flowing through the plurality of LED elements to be constant by the voltage source. Item 3. The LED lighting device according to Item 2. 定電流回路は、ＬＥＤ素子に流れる電流を検出し、その検出電流に基づいて電圧源と前記ＬＥＤ素子との間に接続された電源用スイッチ素子を制御することにより、前記ＬＥＤ素子に流れる電流が一定になるようした請求項３に記載のＬＥＤ点灯装置。   The constant current circuit detects a current flowing through the LED element, and controls a power switch element connected between the voltage source and the LED element based on the detected current. The LED lighting device according to claim 3, wherein the LED lighting device is constant. 定電流源は、ＬＥＤ素子に接続された可変電圧源と定電流回路によって構成され、前記可変電圧源は制御回路から点灯ＬＥＤ素子の数に応じた制御信号を入力し、前記可変電圧源の出力電圧を同時に点灯するＬＥＤ素子の数に応じて可変するようにした請求項１または請求項２に記載のＬＥＤ点灯装置。   The constant current source includes a variable voltage source connected to the LED element and a constant current circuit. The variable voltage source inputs a control signal according to the number of lighting LED elements from the control circuit, and outputs the variable voltage source. The LED lighting device according to claim 1 or 2, wherein the voltage is varied in accordance with the number of LED elements that are simultaneously lit. 電圧源は、ＡＣ電源を入力とし、このＡＣ電源からの入力電流波形を正弦波状かつ入力電圧と同相に制御することを特徴とする請求項３乃至請求項５のいずれか１項に記載のＬＥＤ点灯装置。   6. The LED according to claim 3, wherein the voltage source receives an AC power source and controls an input current waveform from the AC power source in a sine wave shape and in phase with the input voltage. Lighting device. 制御回路は、同時に点灯するＬＥＤ素子の数が、直列に接続された全ＬＥＤ素子の数よりも小さい所定の値以下となるように制御するようにした請求項１〜請求項６のいずれか１項に記載のＬＥＤ点灯装置。   7. The control circuit according to claim 1, wherein the control circuit controls the number of LED elements that are simultaneously turned on to be equal to or less than a predetermined value that is smaller than the number of all LED elements connected in series. LED lighting device as described in the paragraph. 直列に接続された複数のＬＥＤ素子により構成されるＬＥＤ素子群、このＬＥＤ素子群に並列に接続されたスイッチ素子、前記ＬＥＤ素子群と前記スイッチ素子の並列回路を複数組直列に接続したＬＥＤ素子回路網、このＬＥＤ素子回路網に定電流を供給する定電流源、および前記スイッチ素子のオンオフを制御することにより前記ＬＥＤ素子の輝度を前記ＬＥＤ素子群毎に制御する制御回路を備えたＬＥＤ点灯装置。   LED element group composed of a plurality of LED elements connected in series, switch element connected in parallel to the LED element group, and LED element in which a plurality of sets of parallel circuits of the LED element group and the switch element are connected in series LED lighting comprising a circuit network, a constant current source for supplying a constant current to the LED element network, and a control circuit for controlling the brightness of the LED elements for each LED element group by controlling on / off of the switch elements apparatus. ＬＥＤ素子群は、ハイビーム用ＬＥＤ素子群、ロービーム用ＬＥＤ素子群、およびＤＲＬ用ＬＥＤ素子群の何れかであることを特徴とする請求項８に記載のＬＥＤ点灯装置。   9. The LED lighting device according to claim 8, wherein the LED element group is any one of a high beam LED element group, a low beam LED element group, and a DRL LED element group. 請求項１〜請求項９のいずれか１項に記載のＬＥＤ点灯装置を用いた車両用前照灯において、前記ＬＥＤ点灯装置の複数のＬＥＤ素子をマトリクス状に並べたＬＥＤモジュールと、前記複数のＬＥＤ素子から放射される光を各々のＬＥＤ素子に対応して定められた方向に投射する光学ユニットとを備えた車両用前照灯。   In the vehicle headlamp using the LED lighting device according to any one of claims 1 to 9, an LED module in which a plurality of LED elements of the LED lighting device are arranged in a matrix, and the plurality of the LED lighting devices An automotive headlamp comprising: an optical unit that projects light emitted from an LED element in a direction determined corresponding to each LED element.
JP2007308940A 2007-11-29 2007-11-29 Led lighting device, and headlight for vehicle Pending JP2009134933A (en)

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WO2022133672A1 (en) * 2020-12-21 2022-06-30 Foshan Ichikoh Valeo Auto Lighting Systems Co., Ltd. Light assembly for powering lighting functions with different power requirements
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