JP2010153566A - Led driving method - Google Patents

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JP2010153566A
JP2010153566A JP2008329623A JP2008329623A JP2010153566A JP 2010153566 A JP2010153566 A JP 2010153566A JP 2008329623 A JP2008329623 A JP 2008329623A JP 2008329623 A JP2008329623 A JP 2008329623A JP 2010153566 A JP2010153566 A JP 2010153566A
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led array
led
voltage
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Isao Amano
功 天野
Ryuji Yamada
隆二 山田
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Fuji Electric Co Ltd
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Fuji Electric Holdings Ltd
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<P>PROBLEM TO BE SOLVED: To achieve a small-sized, inexpensive configuration of a drive unit of an LED lighting device and enable the LED lighting device to emit uniform light. <P>SOLUTION: To each of a plurality of LED lighting devices 2 connected in parallel to a main power line SL, a series voltage compensator 3 and a current detector 18 detecting a current flowing through the LED lighting devices 2 are connected in series. When a voltage of the main power line SL is applied to the LED lighting devices 2 to turn them on, the current detector 18 detects a current flowing through the LED lighting devices 2, and the series voltage compensator 3 increases/decreases the applied voltage to keep the current constant for current control. Hence an error in brightness between the LED lighting devices 2 each connected in parallel to the main power line SL is adjusted. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

この発明は、主電源ラインに複数台並列に接続され、照明装置の光源として用いられる発光ダイオード（単にＬＥＤとも記す）の駆動方式に関する。   The present invention relates to a driving system for light emitting diodes (also simply referred to as LEDs) that are connected in parallel to a main power supply line and used as a light source of an illumination device.

発光ダイオードは、長寿命で発光効率が高いという特性を有することから、各種の照明装置に広く使用されている。
一般にＬＥＤは、負性の温度特性を有するため、通電状態で周囲温度の上昇等により素子の温度が上昇すると内部抵抗が減少して順方向電流が増加し、そのためにＬＥＤの発光強度が変動したり、さらにはＬＥＤが焼損したりする不都合がある。
このような、不都合を解消するために、従来から特許文献１に示すようにＬＥＤの通電中の電流を検出して、この電流が一定になるように制御することが既に行われている。 Light emitting diodes are widely used in various lighting devices because of their long life and high luminous efficiency.
In general, an LED has a negative temperature characteristic. Therefore, when the temperature of the element rises due to an increase in ambient temperature or the like in an energized state, the internal resistance decreases and the forward current increases, which causes the emission intensity of the LED to fluctuate. Or, further, the LED may burn out.
In order to eliminate such an inconvenience, conventionally, as shown in Patent Document 1, a current during energization of an LED is detected and controlled so that the current becomes constant.

図５に、特許文献１に示されたＬＥＤ駆動装置の例を示す。
図５に示すように、複数のＬＥＤ素子からなるＬＥＤ照明器（ＬＥＤアレイともいう）２と、これを駆動するＬＥＤ照明駆動装置４とから構成される。ＬＥＤ照明駆動装置４は交流電源から供給される交流電圧を整流する整流器１６と、この整流器１６の整流電圧を平滑する平滑コンデンサ１５とからなる直流電源と、ＬＥＤアレイ２に直列に接続されたリアクトル１３およびダイオード１４、ＬＥＤアレイ２に流れる電流を検出する電流検出器１８、ＬＥＤアレイ２に加えられる電圧を断続するＭＯＳトランジスタ１２、このＭＯＳトランジスタ１２のスイッチング制御を行なうスイッチ制御装置１７等から構成される。ＭＯＳトランジスタ（ＭＯＳＦＥＴ）１２は、スイッチ制御装置１７から与えられる周期的なパルス駆動信号により周期的にオン・オフし、ＬＥＤアレイ２に流れる電流を調整する。 FIG. 5 shows an example of the LED driving device disclosed in Patent Document 1.
As shown in FIG. 5, it comprises an LED illuminator (also referred to as an LED array) 2 composed of a plurality of LED elements and an LED illumination driving device 4 for driving the LED illuminator 2. The LED illumination driving device 4 includes a rectifier 16 that rectifies an AC voltage supplied from an AC power source, a DC power source that includes a smoothing capacitor 15 that smoothes the rectified voltage of the rectifier 16, and a reactor connected in series to the LED array 2. 13 and a diode 14, a current detector 18 for detecting a current flowing through the LED array 2, a MOS transistor 12 for intermittently applying a voltage applied to the LED array 2, a switch control device 17 for controlling the switching of the MOS transistor 12, and the like. The The MOS transistor (MOSFET) 12 is periodically turned on / off by a periodic pulse drive signal supplied from the switch control device 17, and adjusts the current flowing through the LED array 2.

特開２００６-２７８５２６号公報JP 2006-278526 A

ところで、図５のようなＬＥＤ駆動装置を、例えば大規模店舗の屋内照明に適用する場合等には、図６のように複数のＬＥＤ駆動装置は並列に接続して使用される。従って、規模が大きくなればなるほど複数台のＬＥＤ駆動装置を必要としてコスト高になるだけでなく、システムが大型化するという問題がある。
一方、コストダウンのために、例えば図７のように１台のＡＣ−ＤＣ変換装置（主電源装置）１を設け、そのＤＣ出力ラインに並列にＬＥＤ（ＬＥＤ照明器２）を接続する方法も考えられる。 Incidentally, when the LED driving device as shown in FIG. 5 is applied to, for example, indoor lighting of a large-scale store, a plurality of LED driving devices are connected in parallel as shown in FIG. Accordingly, there is a problem that the larger the scale is, the more the cost is required because a plurality of LED driving devices are required, and the system becomes larger.
On the other hand, in order to reduce the cost, for example, a single AC-DC converter (main power supply) 1 is provided as shown in FIG. 7, and an LED (LED illuminator 2) is connected in parallel to the DC output line. Conceivable.

しかしながら、図７の方法ではＬＥＤ素子のバラツキや温度特性により、同じ直流電圧を印加しても流れる電流に差異が生じる。これを説明するのが図８であり、同じ電圧を印加しても、電流はＩ，Ｉ'に示すように変化する。ＬＥＤの輝度は流れる電流にほぼ比例するため、ＬＥＤの明るさが異なることになる。
したがって、この発明の課題は装置構成を小型かつ安価にするとともに、均一な発光を可能にすることにある。 However, in the method of FIG. 7, a difference occurs in the flowing current even when the same DC voltage is applied due to variations in LED elements and temperature characteristics. This is illustrated in FIG. 8, and even when the same voltage is applied, the current changes as indicated by I and I ′. Since the brightness of the LED is substantially proportional to the flowing current, the brightness of the LED is different.
Accordingly, an object of the present invention is to make the apparatus configuration small and inexpensive and to enable uniform light emission.

このような課題を解決すため、この出願の請求項１の発明では、主電源ラインに複数台並列に接続された各ＬＥＤアレイに対し、直列に接続された電圧調整手段と、前記ＬＥＤアレイに流れる電流を検出する検出手段とをそれぞれ設け、
前記主電源ラインの電圧が前記ＬＥＤアレイに印加されてＬＥＤアレイが点灯したとき、ＬＥＤアレイに流れる電流を前記検出手段にて検出し、この電流が一定の値になるように前記電圧調整手段にて電圧を増減させて電流を制御することで、互いに並列に接続された各ＬＥＤアレイの輝度の誤差を調整可能にしたことを特徴とする。
この請求項１の発明においては、前記電圧調整手段は、スイッチング素子を用いた電圧変換装置であることができる（請求項２の発明）。 In order to solve such a problem, in the invention of claim 1 of this application, for each LED array connected in parallel to the main power supply line, voltage adjusting means connected in series, and the LED array Detecting means for detecting the flowing current,
When the voltage of the main power supply line is applied to the LED array and the LED array is turned on, the current flowing through the LED array is detected by the detecting means, and the voltage adjusting means is set so that the current becomes a constant value. By controlling the current by increasing / decreasing the voltage, it is possible to adjust the luminance error of each LED array connected in parallel with each other.
In this invention of Claim 1, the said voltage adjustment means can be a voltage converter using a switching element (Invention of Claim 2).

請求項３の発明では、主電源ラインに複数台並列に接続された各ＬＥＤアレイに対し、ＬＥＤアレイを構成する個々のＬＥＤを短絡する短絡手段と、ＬＥＤアレイに流れる電流を検出する検出手段とをそれぞれ設け、
前記主電源ラインの電圧が前記ＬＥＤアレイに印加されてＬＥＤアレイが点灯したとき、ＬＥＤアレイに流れる電流を前記検出手段にて検出し、この電流が一定の値となるように前記短絡手段によりＬＥＤアレイ中の少なくとも１つのＬＥＤを短絡することで、互いに並列に接続された各ＬＥＤアレイの輝度の誤差を調整可能にしたことを特徴とする。 In the invention of claim 3, for each LED array connected in parallel to the main power supply line, short-circuit means for short-circuiting individual LEDs constituting the LED array, and detection means for detecting current flowing in the LED array; Provided,
When the voltage of the main power supply line is applied to the LED array and the LED array is turned on, the current flowing through the LED array is detected by the detection means, and the short-circuit means causes the LED to become a constant value. By short-circuiting at least one LED in the array, it is possible to adjust a luminance error of each LED array connected in parallel to each other.

この発明によれば、装置を小型かつ安価に構成できるだけでなく、ＬＥＤ素子のバラツキや温度特性によって生じる電流の誤差（輝度の誤差）をなくし、均一に発光させることが可能となる。   According to the present invention, not only can the apparatus be configured to be small and inexpensive, but also an error in current (brightness error) caused by variations in LED elements and temperature characteristics can be eliminated, and light can be emitted uniformly.

図１はこの発明の実施の形態を示す回路図である。
同図に示すように、ＬＥＤアレイ２と直列に、直列電圧補償装置３を設けた点が特徴である。
この直列電圧補償装置３は、ＭＯＳトランジスタ１２と、ダイオード１４および直流電源１１とから構成されるチョッパ回路である。また、直流電源１１は図示のように、例えばコンデンサ１０１、充放電器１０２およびバッテリー１０３等から構成される。なお、図１のようにＬＥＤアレイ２と直列電圧補償装置３を直列に接続したものは、図３のように主電源装置１の出力に対し、複数個並列に接続されて１つの照明システムを構成する。 FIG. 1 is a circuit diagram showing an embodiment of the present invention.
As shown in the figure, a feature is that a series voltage compensator 3 is provided in series with the LED array 2.
This series voltage compensator 3 is a chopper circuit composed of a MOS transistor 12, a diode 14 and a DC power supply 11. Further, as shown in the figure, the DC power source 11 is composed of, for example, a capacitor 101, a charger / discharger 102, a battery 103, and the like. As shown in FIG. 1, the LED array 2 and the series voltage compensation device 3 connected in series are connected in parallel to the output of the main power supply device 1 as shown in FIG. Constitute.

以上のような構成で、主電源装置からＬＥＤアレイ２に直流電圧が印加されると、電流が流れてＬＥＤアレイ２が点灯する。ＬＥＤアレイ２を構成する各発光ダイオード素子の特性バラツキや周囲温度等により、各ＬＥＤアレイ２に流れる電流に誤差が生じる。そこで、電流検出器１８によりＬＥＤアレイ２を流れる電流を検出し、その電流が所定値となるように直列電圧補償装置３にて制御する。すなわち、ＭＯＳトランジスタ１２をオン・オフさせ、ＬＥＤアレイ２に掛かる電圧を微調整し電流を制御する。これにて、ＬＥＤアレイ２の輝度のバラツキを解消する。   With the above configuration, when a DC voltage is applied from the main power supply device to the LED array 2, a current flows and the LED array 2 is lit. An error occurs in the current flowing through each LED array 2 due to the characteristic variation of each light emitting diode element constituting the LED array 2 and the ambient temperature. Therefore, the current flowing through the LED array 2 is detected by the current detector 18 and controlled by the series voltage compensator 3 so that the current becomes a predetermined value. That is, the MOS transistor 12 is turned on / off, the voltage applied to the LED array 2 is finely adjusted, and the current is controlled. Thereby, the variation in the brightness of the LED array 2 is eliminated.

いま、ＬＥＤアレイ２の特性が図８の特性１，特性２のように異なるものとし、図３の主電源装置１の出力電圧がＶ１であるとし、ＬＥＤアレイ２に流したい電流をＩとする。ところが、特性２のＬＥＤアレイ２では、この場合の電流はＩ'となる。そこで、対応する直列電圧補償装置３からは調整分ΔＶを出力するが、この調整分ΔＶは（Ｖ２−Ｖ１）で良い。つまり、装置の定格容量は、[（Ｖ２−Ｖ１）×Ｉ]となる。
一方、図５に示す従来例では、各ＬＥＤアレイ２の定格容量は、Ｖ２×Ｉとなる。以上の関係を図示すると、図４となる。（ａ）が従来例、（ｂ）がこの発明の場合を示す。
その結果、この発明の場合の方が小型化，低コスト化できることになる。 Now, it is assumed that the characteristics of the LED array 2 are different as shown by characteristics 1 and 2 in FIG. 8, the output voltage of the main power supply device 1 in FIG. 3 is V1, and the current to be passed through the LED array 2 is I. . However, in the LED array 2 having the characteristic 2, the current in this case is I ′. Therefore, although the adjustment amount ΔV is output from the corresponding series voltage compensator 3, the adjustment amount ΔV may be (V2−V1). That is, the rated capacity of the device is [(V2−V1) × I].
On the other hand, in the conventional example shown in FIG. 5, the rated capacity of each LED array 2 is V2 × I. The above relationship is illustrated in FIG. (A) shows a conventional example, and (b) shows the case of the present invention.
As a result, the present invention can be reduced in size and cost.

図２にこの発明の別の実施の形態を示す。
ここでは、ＬＥＤアレイ２を複数のＬＥＤを直列に接続したものとし、複数のＬＥＤのうちの少なくとも１つ（ここでは、２つ）と並列にスイッチング素子（ＭＯＳトランジスタ）１２が接され、スイッチ制御装置１７はスイッチング素子１２のオン・オフ制御を行なう。
この回路では、ＬＥＤアレイ２が点灯すると、ＬＥＤの電圧−電流特性のバラツキなどにより、印加した電圧に比べて電流が小さくなる場合がある。その場合には、スイッチ制御装置１７によりスイッチング素子１２をオンとし、適当な数のＬＥＤを短絡する。これにより、各ＬＥＤに流れる電流が大きくなり、輝度を上げることが可能となる。 FIG. 2 shows another embodiment of the present invention.
Here, it is assumed that the LED array 2 has a plurality of LEDs connected in series, and a switching element (MOS transistor) 12 is connected in parallel with at least one (two in this case) of the plurality of LEDs, and switch control is performed. The device 17 performs on / off control of the switching element 12.
In this circuit, when the LED array 2 is lit, the current may be smaller than the applied voltage due to variations in the voltage-current characteristics of the LEDs. In that case, the switch control device 17 turns on the switching element 12 to short-circuit an appropriate number of LEDs. Thereby, the electric current which flows into each LED becomes large and it becomes possible to raise a brightness | luminance.

この発明の実施の形態を示す回路図Circuit diagram showing an embodiment of the present invention この発明の別の実施の形態を示す回路図Circuit diagram showing another embodiment of the present invention 図１の装置が適用されるシステム構成図System configuration diagram to which the apparatus of FIG. 1 is applied この発明と従来例の両システムを比較して説明する説明図Explanatory drawing which compares and demonstrates both this invention and the system of a prior art example 従来例を示す回路図Circuit diagram showing a conventional example 図５を適用したシステム構成図System configuration diagram applying FIG. 図５を用いないシステム構成図System configuration without using FIG. ＬＥＤの電圧−電流特性例を示す特性図Characteristic diagram showing voltage-current characteristic example of LED

符号の説明Explanation of symbols

１…主電源装置（ＡＶ−ＤＣ変換装置）、２…ＬＥＤ照明器（ＬＥＤアレイ）、３…直列電圧補償装置、１１…ＤＣ電源、１２…ＭＯＳトランジスタ、１３…リアクトル、１４…ダイオード、１７…スイッチ制御装置、１８…電流検出器、１０１…コンデンサ、１０２…充放電器、１０３…バッテリー、ＳＬ…主電源ライン。


DESCRIPTION OF SYMBOLS 1 ... Main power supply device (AV-DC converter), 2 ... LED illuminator (LED array), 3 ... Series voltage compensator, 11 ... DC power supply, 12 ... MOS transistor, 13 ... Reactor, 14 ... Diode, 17 ... Switch control device, 18 ... current detector, 101 ... capacitor, 102 ... charger / discharger, 103 ... battery, SL ... main power line.


Claims (3)

主電源ラインに複数台並列に接続された各ＬＥＤアレイに対し、直列に接続された電圧調整手段と、前記ＬＥＤアレイに流れる電流を検出する検出手段とをそれぞれ設け、
前記主電源ラインの電圧が前記ＬＥＤアレイに印加されてＬＥＤアレイが点灯したとき、ＬＥＤアレイに流れる電流を前記検出手段にて検出し、この電流が一定の値になるように前記電圧調整手段にて電圧を増減させて電流を制御することで、互いに並列に接続された各ＬＥＤアレイの輝度の誤差を調整可能にしたことを特徴とするＬＥＤ駆動方式。 For each LED array connected in parallel to the main power supply line, a voltage adjusting means connected in series and a detecting means for detecting a current flowing through the LED array are provided,
When the voltage of the main power supply line is applied to the LED array and the LED array is turned on, the current flowing through the LED array is detected by the detecting means, and the voltage adjusting means is set so that the current becomes a constant value. The LED driving method is characterized in that the brightness error of each LED array connected in parallel can be adjusted by controlling the current by increasing / decreasing the voltage. 前記電圧調整手段は、スイッチング素子を用いた電圧変換装置であることを特徴とする請求項１に記載のＬＥＤ駆動方式。   The LED driving method according to claim 1, wherein the voltage adjusting unit is a voltage conversion device using a switching element. 主電源ラインに複数台並列に接続された各ＬＥＤアレイに対し、ＬＥＤアレイを構成する個々のＬＥＤを短絡する短絡手段と、ＬＥＤアレイに流れる電流を検出する検出手段とをそれぞれ設け、
前記主電源ラインの電圧が前記ＬＥＤアレイに印加されてＬＥＤアレイが点灯したとき、ＬＥＤアレイに流れる電流を前記検出手段にて検出し、この電流が一定の値となるように前記短絡手段によりＬＥＤアレイ中の少なくとも１つのＬＥＤを短絡することで、互いに並列に接続された各ＬＥＤアレイの輝度の誤差を調整可能にしたことを特徴とするＬＥＤ駆動方式。 For each LED array connected in parallel to the main power supply line, a short-circuit means for short-circuiting individual LEDs constituting the LED array and a detection means for detecting a current flowing through the LED array are provided, respectively.
When the voltage of the main power supply line is applied to the LED array and the LED array is turned on, the current flowing through the LED array is detected by the detection means, and the short-circuit means causes the LED to become a constant value. An LED driving method characterized in that an error in luminance of each LED array connected in parallel with each other can be adjusted by short-circuiting at least one LED in the array.
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JP2013546174A (en) * 2010-10-19 2013-12-26 コーニンクレッカ フィリップス エヌ ヴェ LED circuit device
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