JP5047373B2 - LED dimmer - Google Patents

LED dimmer Download PDF

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JP5047373B2
JP5047373B2 JP2011052213A JP2011052213A JP5047373B2 JP 5047373 B2 JP5047373 B2 JP 5047373B2 JP 2011052213 A JP2011052213 A JP 2011052213A JP 2011052213 A JP2011052213 A JP 2011052213A JP 5047373 B2 JP5047373 B2 JP 5047373B2
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茂章 山崎
浩行 迫
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パナソニック株式会社
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    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05BELECTRIC HEATING; ELECTRIC LIGHTING NOT OTHERWISE PROVIDED FOR
    • H05B45/00Circuit arrangements for operating light emitting diodes [LED]
    • H05B45/10Controlling the intensity of the light

Description

本発明は、発光ダイオード(以下「LED」と呼ぶ)を光源とし、調光機能を持つLED調光装置に関するものである。   The present invention relates to an LED dimming device that uses a light emitting diode (hereinafter referred to as “LED”) as a light source and has a dimming function.

従来のLED調光装置として、特許文献1(特開2003−157986)に示されているものがある。この従来例は、LEDへの印加電圧の制御と、LED電流を断続するスイッチ素子によるスイッチング調光とを組み合わせたものである。外部からの調光信号を制御回路で受けて、調光度合いが浅い時(明るいとき)にはLEDへの印加電圧は一定にしてスイッチ素子のON/OFFのDUTYを変化させることにより調光を行ない、調光度合いが深い時(暗いとき)にはスイッチ素子のON/OFFのDUTYは一定にしてLEDに印加する電圧を可変制御して調光するものであった。   As a conventional LED light control device, there is one disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 2003-157986). This conventional example is a combination of control of the voltage applied to the LED and switching dimming by a switch element that intermittently switches the LED current. When the dimming signal from the outside is received by the control circuit and the degree of dimming is shallow (when bright), the voltage applied to the LED is kept constant and the dimming is performed by changing the ON / OFF DUTY of the switch element. When the degree of dimming is deep (when dark), the switch element ON / OFF DUTY is kept constant, and the voltage applied to the LED is variably controlled for dimming.

LEDへの印加電圧は一定にして、スイッチ素子のON/OFFのDUTYを変化させることにより調光を行なう場合、スイッチ素子のON/OFFの周波数は、LEDの光がちらついて見えないように高く設定する必要があるが、深い調光時(暗いとき)にはスイッチ素子のON時間が短くなる。特に0%に近い調光時にはスイッチ素子のON時間を高精度に制御することが難しいため、スイッチ素子のON時間を高精度に制御できるところまではスイッチング調光を行ない、それより深い調光では、スイッチ素子のON時間は一定でLED印加電圧を制御して調光を行なうことにより、より深い調光レベルまで調光信号に比例して調光可能としたものである。
特開2003−157986号公報Japanese Unexamined Patent Publication No. 2003-157986 When the dimming is performed by changing the ON / OFF DUTY of the switch element while keeping the voltage applied to the LED constant, the ON / OFF frequency of the switch element is high so that the LED light does not flicker. Although it is necessary to set, the ON time of the switch element is shortened at the time of deep dimming (when dark). Especially when dimming near 0%, it is difficult to control the ON time of the switch element with high accuracy, so switching dimming is performed until the ON time of the switch element can be controlled with high accuracy. The ON time of the switch element is constant, and the dimming can be performed in proportion to the dimming signal up to a deeper dimming level by performing dimming by controlling the LED applied voltage. When the dimming is performed by changing the ON / OFF DUTY of the switch element while keeping the voltage applied to the LED constant, the ON / OFF frequency of the switch element is high so that the LED light does not flicker. Although it is necessary to set, the ON time of the switch element is shortened at the time of deep dimming (when dark). Especially when dimming near 0%, it is difficult to control the ON time of the switch element with high accuracy, so switching dimming is performed until the ON time of the switch element can be controlled with high accuracy. The ON time of the switch element is constant, and the dimming can be performed in proportion to the dimming signal up to a deeper dimming level by performing dimming by controlling the LED applied voltage.
JP 2003-157986 A JP 2003-157986 A

しかし、従来のLED調光装置では、LED電流が大きい場合に、LED電流を断続すると、パルス電流が大きなノイズを発生するという問題があった。一方、LEDに流れる電流を連続電流とし、電流の大きさを制御して調光する場合、電流を小さくしていくと、LED素子のばらつきにより、同じ電流を流しても明るさにばらつきが出てくるという問題があった。   However, in the conventional LED light control device, when the LED current is large, there is a problem that if the LED current is intermittent, the pulse current generates a large noise. On the other hand, when the current flowing through the LED is a continuous current and dimming is performed by controlling the magnitude of the current, if the current is reduced, the brightness will vary even if the same current is applied due to the variation in the LED elements. There was a problem of coming.

本発明の目的は、LED電流が大きい場合にもノイズが発生しにくく、調光を深くしても明るさにばらつきが出にくいLED調光装置を提供することにある。   An object of the present invention is to provide an LED dimming device in which noise hardly occurs even when the LED current is large, and brightness does not easily vary even when the dimming is deepened.

本発明によれば、上記の課題を解決するために、図1に示すように、LED負荷4に流れる電流の大きさを可変制御する電流調整手段(定電流回路6)と、LED負荷4に流れる電流を断続制御するスイッチ手段(トランジスタQ1)と、調光器1から出力される調光信号を受けて前記電流調整手段と前記スイッチ手段を制御する調光制御手段(マイコン5)とを備えるLED調光装置であって、前記調光制御手段は、前記調光器1から出力される調光信号が所定のレベルよりも高輝度側の場合、LED負荷4に流れる電流を連続電流とし、流れる電流の大きさによりLED負荷4を調光し、前記調光器1から出力される調光信号が前記所定のレベルよりも低輝度側の場合、LED負荷4に流れる電流をパルス状にして、その波形の平均値を変化させることによりLED負荷4を調光し、前記所定のレベルは、図3に示すように、LED負荷4のV−I特性において、電流変化に対する電圧変化の割合を求め、該割合が、定格電流を流したときに比べて3〜5倍となる範囲に設定したことを特徴とするものである。 According to the present invention, in order to solve the above problem, as shown in FIG. 1, current adjusting means (constant current circuit 6) that variably controls the magnitude of the current flowing through the LED load 4, and the LED load 4 A switch means (transistor Q1) for intermittently controlling the flowing current, and a dimming control means (microcomputer 5) for receiving the dimming signal output from the dimmer 1 and controlling the current adjusting means and the switch means. In the LED dimming device, the dimming control means sets the current flowing through the LED load 4 as a continuous current when the dimming signal output from the dimmer 1 is on a higher luminance side than a predetermined level, The LED load 4 is dimmed according to the magnitude of the flowing current, and when the dimming signal output from the dimmer 1 is on the lower luminance side than the predetermined level, the current flowing through the LED load 4 is pulsed. , The average value of the waveform The LED load 4 dimmed by reduction, the predetermined level, as shown in FIG. 3, the V-I characteristics of the LED load 4, determine the ratio of voltage change to current change, the ratio is, the rated It is characterized in that it is set in a range that is 3 to 5 times the current flow.

本発明によると、調光が浅く明るいときはLED負荷に流れる電流を変化させ、調光が深く暗いときはLED負荷に流れる電流をパルス状にして、その波形の平均値で調光することにより、調光が明るいときにノイズが発生しにくく、調光を深くしても明るさにばらつきが出にくいLED調光装置を実現できる。   According to the present invention, when the dimming is shallow and bright, the current flowing through the LED load is changed, and when the dimming is deep and dark, the current flowing through the LED load is changed to pulses, and the dimming is performed by the average value of the waveform. Therefore, it is possible to realize an LED light control device that hardly generates noise when the light control is bright, and that does not cause variations in brightness even when the light control is deepened.

(実施形態1)
本発明の実施形態1の回路構成を図1に示す。本実施形態は、調光器1と、電源2と、LED点灯装置3と、LED負荷4とから構成される。また、LED点灯装置3は、マイコン5と、定電流回路6と、抵抗R1と、トランジスタQ1とから構成される。定電流回路6は、マイコン5からの信号により指定された定電流を流すように構成されている。マイコン5は、調光器1の調光信号を読み取り、トランジスタQ1のON/OFFを制御すると共に定電流回路6の電流値を設定する機能を有する。
(Embodiment 1)
FIG. 1 shows a circuit configuration of Embodiment 1 of the present invention. The present embodiment includes a dimmer 1, a power source 2, an LED lighting device 3, and an LED load 4. The LED lighting device 3 includes a microcomputer 5, a constant current circuit 6, a resistor R1, and a transistor Q1. The constant current circuit 6 is configured to flow a constant current specified by a signal from the microcomputer 5. The microcomputer 5 has a function of reading a dimming signal from the dimmer 1, controlling ON / OFF of the transistor Q 1, and setting a current value of the constant current circuit 6. FIG. 1 shows a circuit configuration of Embodiment 1 of the present invention. The present embodiment includes a dimmer 1, a power source 2, an LED lighting device 3, and an LED load 4. The LED lighting device 3 includes a microcomputer 5, a constant current circuit 6, a resistor R1, and a transistor Q1. The constant current circuit 6 is configured to flow a constant current specified by a signal from the microcomputer 5. The microcomputer 5 has a function of reading a dimming signal from the dimmer 1, controlling ON / OFF of the transistor Q 1, and setting a current value of the constant current circuit 6.

マイコン5には、あらかじめ定められた調光レべル(a)があり、その調光レベル(a)より明るい領域ではトランジスタQ1をONに固定し、定電流回路6の設定電流を変化させることで調光を行う。これをDC調光モードという。また、その調光レベル(a)より暗い領域では、定電流回路6の設定電流を固定し、トランジスタQ1をON/OFFし、そのDUTYを変化させることにより、調光を行う。これをDUTY調光モードという。   The microcomputer 5 has a predetermined dimming level (a). In a region brighter than the dimming level (a), the transistor Q1 is fixed to ON and the set current of the constant current circuit 6 is changed. Adjust the light with. This is called a DC dimming mode. In a region darker than the dimming level (a), the set current of the constant current circuit 6 is fixed, the transistor Q1 is turned ON / OFF, and the DUTY is changed to perform dimming. This is called a DUTY dimming mode.

本実施形態の動作を図2に示す。図2(イ)は調光信号出力のレベルと光出力の関係、図2(ロ)は調光信号出力のレベルとLED電流(ピーク値)の関係、図2(ハ)は調光信号出力のレベルとパルス波形のDUTYの関係を示している。   The operation of this embodiment is shown in FIG. 2A shows the relationship between the light control signal output level and the light output, FIG. 2B shows the relationship between the light control signal output level and the LED current (peak value), and FIG. 2C shows the light control signal output. The relationship between the level and the DUTY of the pulse waveform is shown.

調光レベル(a)の設定は、LED素子のV−I特性により決定する。あるLED素子のV−I特性が、図3のようであったとする。図中、Vfは順方向電圧、Ifは順方向電流である。定格電流時の△V/△IをAとする。LED素子に流す電流を下げていくと、△V/△I(=Bとする)は大きくなっていく。Bの値が、Aの値に対して、3倍〜5倍以上になると、LED素子は不安定になり、ばらつきも大きくなるので、そうならない領域をDC調光モードとするように、図2の調光レベル(a)を設定する。また、DUTY調光モード時のピーク電流は、図2(ロ)に示すように、DC調光モード時の最小電流に設定すると、モードの切り替え部分での調光が連続的となり、スムーズな調光が可能となる。   The setting of the dimming level (a) is determined by the VI characteristic of the LED element. It is assumed that the VI characteristic of a certain LED element is as shown in FIG. In the figure, Vf is a forward voltage, and If is a forward current. Let ΔV / ΔI at the rated current be A. As the current flowing through the LED element is lowered, ΔV / ΔI (= B) increases. When the value of B is 3 to 5 times or more than the value of A, the LED element becomes unstable and the variation becomes large, so that the region where this does not occur is set to the DC dimming mode. The light control level (a) is set. In addition, as shown in FIG. 2 (b), when the peak current in the DUTY dimming mode is set to the minimum current in the DC dimming mode, the dimming at the mode switching portion becomes continuous and smooth dimming. Light is possible.

本実施形態によると、調光レベルが高輝度側の場合に、連続電流で点灯するため、LED電流が大きくなっても、ノイズが発生しにくく、また、調光レベルが低輝度側の場合は、間欠電流で点灯し、ピーク電流は、素子の明るさのばらつきが問題にならないレべルで点灯しているため、調光を深くしても明るさにばらつきが出にくいLED調光装置を提供することが可能となった。   According to this embodiment, when the dimming level is on the high luminance side, it is lit with a continuous current, so even if the LED current increases, noise is less likely to occur, and when the dimming level is on the low luminance side The LED dimming device is lit with intermittent current, and the peak current is lit at a level where variations in brightness of the elements do not become a problem. It became possible to provide.

なお、調光器1の調光信号出力は、アナログ信号(DC0V〜10Vなど)であっても良いし、DUTY信号(1KHz、10Vなど)であっても良いし、デジタル信号(DMX信号など)であっても良い。また、電源2は、ACであってもDCであっても艮い。LED負荷4は、素子1個で構成されたLEDユニットでも良いし、複数のLED素子で構成されたLEDユニットであっても良い。   The dimming signal output of the dimmer 1 may be an analog signal (DC 0 V to 10 V, etc.), a DUTY signal (1 KHz, 10 V, etc.), or a digital signal (DMX signal, etc.). It may be. The power source 2 may be either AC or DC. The LED load 4 may be an LED unit constituted by one element or an LED unit constituted by a plurality of LED elements.

また、LED負荷4に代えて、DC電源やパルス状の電源で点灯できる負荷であれば任意の負荷に代替可能であり、有機ELなどでも同様の効果を得ることが出来る。   Further, any load that can be lit by a DC power source or a pulsed power source instead of the LED load 4 can be substituted for an arbitrary load, and the same effect can be obtained with an organic EL or the like.

上記DUTY調光モードは、LEDに流れる電流が矩形波となるが、これは最も効果のある波形であり、パルス状の波形は、サイン波形でも、三角波形でも、平坦なDC波形以外の波形であれば、同様の効果が得られる。 In the DUTY dimming mode, the current flowing through the LED is a rectangular wave, which is the most effective waveform, and the pulsed waveform is a waveform other than a sine waveform, triangular waveform, or flat DC waveform. If there is, the same effect can be obtained.

(実施形態2)
本発明の実施形態2の回路構成を図4に示す。 The circuit configuration of the second embodiment of the present invention is shown in FIG. 本実施形態は、調光器1と、電源2と、LED点灯装置3と、LED負荷4とから構成される。 The present embodiment includes a dimmer 1, a power supply 2, an LED lighting device 3, and an LED load 4. また、LED点灯装置3は、マイコン5と、定電流回路6と、抵抗R1,R2と、MOSFET等の半導体スイッチ素子Q1から構成される。 Further, the LED lighting device 3 is composed of a microcomputer 5, a constant current circuit 6, resistors R1 and R2, and a semiconductor switch element Q1 such as a MOSFET. (Embodiment 2) (Embodiment 2)
FIG. 4 shows a circuit configuration of the second embodiment of the present invention. The present embodiment includes a dimmer 1, a power source 2, an LED lighting device 3, and an LED load 4. The LED lighting device 3 includes a microcomputer 5, a constant current circuit 6, resistors R1 and R2, and a semiconductor switch element Q1 such as a MOSFET. FIG. 4 shows a circuit configuration of the second embodiment of the present invention. The present embodiment includes a dimmer 1, a power source 2, an LED lighting device 3, and an LED load 4. The LED lighting device 3 includes a microcomputer 5 , a constant current circuit 6, LEDs R1 and R2, and a semiconductor switch element Q1 such as a MOSFET.

定電流回路6は、マイコン5からの電圧信号により、指定された定電流を流すように構成されている。マイコン5は、調光器1の調光信号を読み取り、スイッチ素子Q1のON/OFFを制御すると共に定電流回路6の電流値を設定する機能を有する。調光器1からの調光信号は照明で一般的に使用されているDMX信号とするが、DMX信号は、調光レべルが256レベル(1バイト)であり、LEDを調光するのに十分ではない。従って、スムーズな調光をするため、データを2バイト使用して、0〜65535の数値データを調光レベルの調光信号とし、0が消灯で、65535が100%点灯としている。   The constant current circuit 6 is configured to flow a specified constant current according to a voltage signal from the microcomputer 5. The microcomputer 5 has a function of reading a dimming signal from the dimmer 1, controlling ON / OFF of the switch element Q 1, and setting a current value of the constant current circuit 6. The dimming signal from the dimmer 1 is a DMX signal that is generally used in lighting, but the DMX signal has a dimming level of 256 levels (1 byte) and dims the LED. Not enough. Therefore, in order to perform smooth dimming, 2 bytes of data are used, numerical data from 0 to 65535 is used as a dimming signal of dimming level, 0 is turned off, and 65535 is turned on 100%.

今、調光器1からの信号が最大値の65535である場合に、マイコン5は、スイッチ素子Q1をOFFして、定電流回路6に最大電流(例えば1A)を流すように指示する。すると、LED負荷4には、1Aの電流が流れる。次に、約50%に調光を絞り、調光信号の値として32768を受信したとすると、マイコン5は、定電流回路6に半分の電流500mAを流すように指示し、LED負荷4の光も約50%となる。   Now, when the signal from the dimmer 1 is the maximum value 65535, the microcomputer 5 turns off the switch element Q1 and instructs the constant current circuit 6 to flow the maximum current (for example, 1 A). Then, a current of 1 A flows through the LED load 4. Next, assuming that dimming is reduced to about 50% and 32768 is received as the value of the dimming signal, the microcomputer 5 instructs the constant current circuit 6 to flow a half current of 500 mA, and the light of the LED load 4 Is also about 50%.

更に少し調光を絞り、調光信号の値として32767の信号を受信した場合、マイコン5は定電流回路6に流れる電流をゼロにし、スイッチ素子Q1をONする。この場合、スイッチ素子Q1をONした際に、ほぼ500mAの電流が流れるようにあらかじめ抵抗R2を設定していれば、この時のLED電流は500mAとなり、LED負荷4の光もほぼ50%であり、光の変化はほとんど無い。   When the dimming is further reduced and the signal of 32767 is received as the value of the dimming signal, the microcomputer 5 sets the current flowing through the constant current circuit 6 to zero and turns on the switch element Q1. In this case, if the resistor R2 is set in advance so that a current of approximately 500 mA flows when the switch element Q1 is turned on, the LED current at this time is 500 mA, and the light of the LED load 4 is also approximately 50%. There is almost no change in light.

更に半分に調光を絞り、調光信号の値として16384の信号を受信した場合、スイッチ素子Q1をON/OFFし、DUTY50%とすると、LED負荷4の明るさは約25%になる。   When the dimming is further reduced to half and a signal of 16384 is received as the dimming signal value, when the switch element Q1 is turned ON / OFF and DUTY is 50%, the brightness of the LED load 4 is about 25%.

更に半分に調光を絞り、調光信号の値として8192の信号を受信した場合、スイッチ素子Q1をON/OFFし、DUTY25%とすることで、LED負荷4の明るさを12.5%にすることが出来る。   When the dimming is further reduced to half and the signal of 8192 is received as the dimming signal value, the brightness of the LED load 4 is reduced to 12.5% by turning on / off the switch element Q1 to DUTY 25%. I can do it.

この際に、スイッチ素子Q1をON/OFFする繰り返しの周波数が低いと、ちらつきの原因になるため、一般的には60Hz以上の繰り返し周波数が必要である。また、ビデオ撮影などでフリッカが出ないようにするためには、更に高い周波数(300Hz以上など)で点滅させる必要がある。   At this time, if the repetition frequency for turning on / off the switching element Q1 is low, flickering is caused. Therefore, a repetition frequency of 60 Hz or more is generally required. Further, in order to prevent flicker from occurring during video shooting or the like, it is necessary to blink at a higher frequency (300 Hz or higher).

一方、マイコン5の能力に制限が無いとすると、繰り返し周波数の上限はスイッチ素子Q1の応答速度が限界となり、仮にスイッチ素子Q1の応答速度を10n秒として、0.1%の調光を可能にする場合を想定すると、1/(10n秒×(1/0.1%))=100kHzが繰り返し周波数の上限となる。しかし、繰り返し周波数を高くすると電力損失が大きくなり、ノイズも出やすくなるので繰り返し周波数については、下限近くの周波数を選択するのが良い。簡単のため、ビデオ撮影などでもフリッカが発生しない周波数として、繰り返し周波数を1000Hzとする。   On the other hand, if there is no limitation on the capability of the microcomputer 5, the upper limit of the repetition frequency is limited by the response speed of the switch element Q1, and the response speed of the switch element Q1 is assumed to be 10 nsec. Assuming the case, 1 / (10 nsec × (1 / 0.1%)) = 100 kHz is the upper limit of the repetition frequency. However, when the repetition frequency is increased, power loss increases and noise is likely to be generated. Therefore, it is preferable to select a frequency near the lower limit for the repetition frequency. For simplicity, the repetition frequency is set to 1000 Hz as a frequency at which flicker does not occur even in video shooting.

引き続き、更に調光を絞り、DUTYを10%(LEDの光は5%)とすれば、100μ秒のパルス幅となり、DUTYを1%(LEDの光は0.5%)とすれば、10μ秒のパルス幅が必要となる。LEDをスムーズに調光する場合、少なくとも0.1%程度の調光が必要であるので、必要なDUTYは、0.2%(LEDの光は0.1%)となり、その際のパルス幅は2μ秒になる。   If the dimming is further narrowed down and the DUTY is 10% (LED light is 5%), the pulse width is 100 μs, and if the DUTY is 1% (LED light is 0.5%), 10 μm A pulse width of seconds is required. When dimming an LED smoothly, dimming of at least about 0.1% is necessary, so the required DUTY is 0.2% (LED light is 0.1%), and the pulse width at that time Becomes 2 μs.

通常、マイコンでこのパルス幅を実現する場合、高性能のマイコンや、外付けの回路などが必要となり、コストが高くなってしまう。そこで、DUTYが2%(LEDの光は1%)になった時点で、繰り返し周波数を1桁下げて、100Hzなどの低い周波数に変更すると、パルス幅は200μ秒となり、DUTY0.2%でも20μ秒のパルス幅で調光することが可能となる。   Usually, when this pulse width is realized by a microcomputer, a high-performance microcomputer, an external circuit, and the like are required, resulting in an increase in cost. Therefore, when the DUTY is 2% (LED light is 1%), if the repetition frequency is lowered by one digit and changed to a low frequency such as 100 Hz, the pulse width becomes 200 μsec, and even if DUTY 0.2%, 20 μ Dimming with a pulse width of seconds is possible.

本実施形態の動作を図5〜図7に示す。図5は調光信号出力のレベルと光出力の関係、図6は調光信号出力のレベルとLED電流(ピーク値)の関係、図7は調光信号出力のレベルとDUTYの関係を示している。   The operation of this embodiment is shown in FIGS. 5 shows the relationship between the light control signal output level and the light output, FIG. 6 shows the relationship between the light control signal output level and the LED current (peak value), and FIG. 7 shows the relationship between the light control signal output level and DUTY. Yes.

この場合でも、繰り返し周波数を60Hz以上にしておけば、視感上はちらつきが発生しないため問題はない。また、100Hzなどの低い点滅周波数では、ビデオ撮影などでのフリッカの発生は避けられないが、ビデオ撮影の際の光源として使用される場合は、調光の明るい領域で使用されると考えられるため、これも問題とはならない。   Even in this case, if the repetition frequency is set to 60 Hz or more, there is no problem because flicker does not occur in terms of visual feeling. In addition, flickering during video shooting is unavoidable at a low blinking frequency such as 100 Hz, but when used as a light source for video shooting, it is considered to be used in a brightly lit area. This is also not a problem.

上記構成とすることにより、負荷電流の大きなLEDを調光した際にもノイズの発生が少なく、深くまで調光した際のLEDの光のばらつきを少なくすることが出来、調光比を大きくとり、スムーズな調光が出来るLED調光装置を提供することが可能となった。   By adopting the above configuration, noise generation is small even when dimming an LED with a large load current, variation in the LED light when dimming deeply can be reduced, and the dimming ratio is increased. It has become possible to provide an LED dimming device capable of smooth dimming.

なお、上記説明においては、調光信号が50%の時にDC調光モードからDUTY調光モードへ、調光信号が1%の時にDUTY調光モードの繰り返し周波数を1000Hzから100Hzへと切り替えているが、切り替えの調光レベルは、適宜変更することが出来るし、繰り返し周波数の変更についても、更に周波数の種類を増やし、周波数を切り替える調光レベルを多段階に増やしても同様の効果が得られる。また、1000Hzから100Hzに切り替えるのではなく、1000HzでのONパルス幅を固定としたまま、繰り返し周波数を下げて調光する手段(周波数調光)を用いても良い。   In the above description, when the dimming signal is 50%, the DC dimming mode is switched to the DUTY dimming mode, and when the dimming signal is 1%, the repetition frequency of the DUTY dimming mode is switched from 1000 Hz to 100 Hz. However, the dimming level for switching can be changed as appropriate, and the same effect can be obtained by increasing the frequency types and increasing the dimming level for switching the frequency in multiple stages even when changing the repetition frequency. . Further, instead of switching from 1000 Hz to 100 Hz, means (frequency dimming) for dimming by reducing the repetition frequency while fixing the ON pulse width at 1000 Hz may be used.

(実施形態3)
図8は本発明の実施形態3の全体構成を示す回路図である。本実施形態では、2つのフィードバック制御回路11,12を有するフライバック型DC−DCコンバータ10によりLED負荷4の点灯回路を構成している。以下、その回路構成について説明する。
(Embodiment 3)
FIG. 8 is a circuit diagram showing the overall configuration of Embodiment 3 of the present invention. In the present embodiment, a lighting circuit for the LED load 4 is configured by a flyback DC-DC converter 10 having two feedback control circuits 11 and 12. Hereinafter, the circuit configuration will be described.

商用交流電源(AC100V、50/60Hz)に接続される交流入力端子21,22には、過電圧保護素子ZNRが並列接続されると共に、ダイオードブリッジDBの交流入力端子が接続されている。ダイオードブリッジDBの直流出力端子には、平滑コンデンサC1が並列接続されている。   Overvoltage protection elements ZNR are connected in parallel to AC input terminals 21 and 22 connected to a commercial AC power supply (AC 100 V, 50/60 Hz), and an AC input terminal of a diode bridge DB is connected. A smoothing capacitor C1 is connected in parallel to the DC output terminal of the diode bridge DB.

平滑コンデンサC1には、駆動回路14の出力端子Q−G間を介して絶縁トランスT1の1次巻線が接続されている。駆動回路14は出力端子Q−G間に図示しないパワーMOSFETを内蔵しており、出力端子Q−G間を短絡状態(ON状態)と開放状態(OFF状態)に高周波で切り替えることにより、絶縁トランスT1の1次巻線を高周波で励磁する。絶縁トランスT1の2次巻線には、整流用のダイオードD1を介して出力コンデンサC2が接続されている。以上の回路によりDC−DCコンバータ10を構成している。   The smoothing capacitor C1 is connected to the primary winding of the insulating transformer T1 via the output terminal Q-G of the drive circuit 14. The drive circuit 14 has a built-in power MOSFET (not shown) between the output terminals Q and G. By switching between the output terminals Q and G between a short circuit state (ON state) and an open state (OFF state) at high frequency, an isolation transformer is provided. The primary winding of T1 is excited at high frequency. An output capacitor C2 is connected to the secondary winding of the insulating transformer T1 via a rectifying diode D1. The DC-DC converter 10 is configured by the above circuit.

出力コンデンサC2には、LED負荷4と電流検出抵抗Raとスイッチング素子Q1の直列回路が並列接続されている。スイッチング素子Q1は駆動回路14によりON/OFF状態を制御され、高輝度出力時には常時ON状態であり、低輝度出力時には人の眼に感じない程度の周期でON/OFF駆動される。   A series circuit of an LED load 4, a current detection resistor Ra, and a switching element Q1 is connected in parallel to the output capacitor C2. The switching element Q1 is controlled to be turned on / off by the drive circuit 14, and is always turned on during high luminance output, and is turned on / off at a cycle that does not feel to human eyes during low luminance output.

電流フィードバック制御回路11は、電流検出抵抗Raの両端電圧を検出し、フィードバック制御切替手段13を介して駆動回路14に負荷電流の検出値をフィードバックする。   The current feedback control circuit 11 detects the voltage across the current detection resistor Ra, and feeds back the detected value of the load current to the drive circuit 14 via the feedback control switching means 13.

電圧フィードバック制御回路12は、出力コンデンサC2の両端電圧を検出し、フィードバック制御切替手段13を介して駆動回路14に負荷電圧の検出値をフィードバックする。   The voltage feedback control circuit 12 detects the voltage across the output capacitor C2, and feeds back the detected value of the load voltage to the drive circuit 14 via the feedback control switching means 13.

フィードバック制御切替手段13は、電流フィードバック制御回路11と電圧フィードバック制御回路12の各検出値を入力し、高輝度出力時には電流フィードバック制御回路11の検出値を駆動回路14にフィードバックし、低輝度出力時には電圧フィードバック制御回路12の検出値を駆動回路14にフィードバックする。   The feedback control switching means 13 inputs the detection values of the current feedback control circuit 11 and the voltage feedback control circuit 12 and feeds back the detection value of the current feedback control circuit 11 to the drive circuit 14 at the time of high luminance output, and at the time of low luminance output. The detection value of the voltage feedback control circuit 12 is fed back to the drive circuit 14.

駆動回路14は調光制御部15を内蔵している。調光制御部15は、駆動回路14の出力端子Q−G間を高周波でON/OFFする周波数やON時間幅を可変制御すると共に、低輝度出力時には、スイッチング素子Q1を人の眼に感じない程度の周期でON/OFF駆動するための制御信号を生成する。   The drive circuit 14 includes a dimming control unit 15. The dimming control unit 15 variably controls the frequency and ON time width at which the output terminal Q-G of the drive circuit 14 is turned ON / OFF at a high frequency, and does not feel the switching element Q1 to human eyes at the time of low luminance output. A control signal for ON / OFF driving is generated at a certain cycle.

調光信号入力端子23,24には、例えば、周波数1KHz、DC10Vのパルス幅の矩形波信号よりなる調光信号が入力される。この調光信号は、信号変換回路16により調光信号のDUTYに応じた電圧信号に変換されて、調光制御部15及びフィードバック制御切替手段13に入力される。   To the dimming signal input terminals 23 and 24, for example, a dimming signal including a rectangular wave signal having a frequency of 1 kHz and a pulse width of DC 10 V is input. The dimming signal is converted into a voltage signal corresponding to the DUTY of the dimming signal by the signal conversion circuit 16 and input to the dimming control unit 15 and the feedback control switching unit 13.

調光制御部15は、調光信号を信号変換回路16によりDC電圧に変換した信号と、フィードバック制御切替手段13からのフィードバック信号とが入力され、フィードバック信号が調光レベルに応じた適正な信号レベルとなるような制御を行う。   The dimming control unit 15 receives the signal obtained by converting the dimming signal into a DC voltage by the signal conversion circuit 16 and the feedback signal from the feedback control switching unit 13, and the feedback signal is an appropriate signal corresponding to the dimming level. Control to reach the level.

図9は電流フィードバック制御回路11の具体例、図10は電圧フィードバック制御回路12の具体例、図11はフィードバック制御切替手段13の具体例を示している。   9 shows a specific example of the current feedback control circuit 11, FIG. 10 shows a specific example of the voltage feedback control circuit 12, and FIG. 11 shows a specific example of the feedback control switching means 13.

図9の電流フィードバック制御回路11は、LED負荷4に流れる電流を抵抗Raで電圧に変換し、その電圧をIC1に入力し、そのカソード・アノード間に流れる電流をフォトカプラPC1の発光素子に流し、図11に示すフォトカプラPC1の受光素子に伝達することで、フィードバック制御を行う方式である。   The current feedback control circuit 11 in FIG. 9 converts the current flowing through the LED load 4 into a voltage with the resistor Ra, inputs the voltage to the IC 1, and flows the current flowing between the cathode and the anode through the light emitting element of the photocoupler PC1. This is a method of performing feedback control by transmitting to the light receiving element of the photocoupler PC1 shown in FIG.

図10の電圧フィードバック制御回路12は、LED負荷4と抵抗Raに印加される負荷電圧を抵抗R5,R6で分圧してトランジスタTr1のベースに印加し、ツェナーダイオードZD1のツェナー電圧との差分に応じてトランジスタTr1に流れるコレクタ電流をフォトカプラPC2の発光素子に流し、図11に示すフォトカプラPC2の受光素子に伝達してフィードバック制御を行う方式である。   The voltage feedback control circuit 12 in FIG. 10 divides the load voltage applied to the LED load 4 and the resistor Ra by the resistors R5 and R6 and applies it to the base of the transistor Tr1, and according to the difference from the Zener voltage of the Zener diode ZD1. Thus, the collector current flowing through the transistor Tr1 is passed through the light emitting element of the photocoupler PC2 and transmitted to the light receiving element of the photocoupler PC2 shown in FIG. 11 to perform feedback control.

図11のフィードバック制御切替手段13は、図9に示す電流フィードバック制御回路11からのフィードバック信号をフォトカプラPC1で受けて、図10に示す電圧フィードバック制御回路12からのフィードバック信号をフォトカプラPC2で受けて、調光レベルに応じてスイッチング素子Q2,Q3のいずれか一方をON、他方をOFFすることにより、フォトカプラPC1、PC2の受光素子(フォトトランジスタ)のどちらかが駆動回路14のフィードバック端子FBにフィードバック信号を入力するように構成されている。   11 receives the feedback signal from the current feedback control circuit 11 shown in FIG. 9 by the photocoupler PC1, and receives the feedback signal from the voltage feedback control circuit 12 shown in FIG. 10 by the photocoupler PC2. Thus, either one of the switching elements Q2 and Q3 is turned on and the other is turned off according to the dimming level, so that one of the light receiving elements (phototransistors) of the photocouplers PC1 and PC2 is fed back to the feedback terminal FB of the drive circuit 14. Is configured to input a feedback signal.

スイッチング素子Q2がON、スイッチング素子Q3がOFFの場合は、定電流フィードバック制御され、スイッチング素子Q1はON状態で維持される。反対に、スイッチング素子Q2がOFF、スイッチング素子Q3がONの場合は定電圧フィードバック制御され、コンデンサC2の出力電圧が一定という条件の下で、スイッチング素子Q1のDUTY可変制御によって調光制御が可能となる。スイッチング素子Q1はDUTY調光制御を行う時のON/OFFスイッチである。   When the switching element Q2 is ON and the switching element Q3 is OFF, constant current feedback control is performed, and the switching element Q1 is maintained in the ON state. On the contrary, when switching element Q2 is OFF and switching element Q3 is ON, constant voltage feedback control is performed, and dimming control can be performed by DUTY variable control of switching element Q1 under the condition that the output voltage of capacitor C2 is constant. Become. The switching element Q1 is an ON / OFF switch when performing DUTY dimming control.

本実施形態の動作を先述の図2の調光カーブで説明する。図2(イ)は調光信号出力に対する光出力の変化を模擬的に示したもので、調光信号(DUTY比)が100%の場合が最大光出力になり、0%の場合が調光下限域となることを示している。調光DUTY比(%)に対して、光出力が直線的に低下しているが、特に直線に限らず、ある程度曲線を持った特性でも特に問題は無い。この調光カーブの途中(調光信号a%、光出力b)のポイントを制御方式の切替ポイントとし、そのポイントよりも高輝度側の出力のときは、スイッチング素子Q1は常にON状態で、電流フィードバック制御が掛かった状態である。また、上記ポイントよりも低輝度側の出力のときは、電圧フィードバック制御の掛かった状態であり、スイッチング素子Q1を人の眼に感じない程度の周期でON/OFF駆動し、調光信号に応じてDUTY可変制御を行うものである。   The operation of this embodiment will be described with reference to the dimming curve of FIG. FIG. 2 (a) schematically shows the change of the light output with respect to the dimming signal output. When the dimming signal (DUTY ratio) is 100%, the maximum light output is obtained, and when the dimming signal is 0%, the dimming is performed. It shows that it becomes the lower limit. The light output decreases linearly with respect to the dimming DUTY ratio (%). However, there is no particular problem even if the characteristic is not limited to a straight line but has a curve to some extent. A point in the middle of the dimming curve (dimming signal a%, light output b) is used as a control system switching point, and when the output is on the higher luminance side than that point, the switching element Q1 is always in the ON state, The feedback control is applied. Further, when the output is on the lower luminance side than the above point, the voltage feedback control is applied, and the switching element Q1 is driven ON / OFF with a period that is not perceived by human eyes, according to the dimming signal. Thus, DUTY variable control is performed.

同様の制御は、実施形態2(図5〜図7)についても適用でき、スイッチング素子Q1を調光信号に応じてDUTY可変制御を行なう調光領域では電圧フィードバック制御を選択し、スイッチング素子Q1をON状態として電流可変制御により調光を行うDC調光領域では電流フィードバック制御を選択すれば良い。   The same control can be applied to the second embodiment (FIGS. 5 to 7), and the voltage feedback control is selected in the dimming region where the switching element Q1 performs the DUTY variable control according to the dimming signal, and the switching element Q1 Current feedback control may be selected in a DC dimming region where dimming is performed by current variable control in the ON state.

なお、スイッチング素子Q2,Q3のON/OFFを切替えるポイントでは、切替時のタイミングにより誤動作、ちらつきなどが発生する場合が有り得るので、スイッチング素子Q2、Q3を両方ともONする範囲を設定するか、あるいは、図8のフィードバック制御切替手段13が電圧フィードバック制御回路12の検出値を選択しているときに電流フィードバック制御回路11の検出値を調光制御部15で同時に参照して、誤動作やちらつきを無くすような制御を行うようにすることも出来る。図12に概念図として、定電流制御と定電圧制御を同時に行う範囲があっても良いことを示している。   Note that at the point of switching ON / OFF of the switching elements Q2 and Q3, malfunction or flicker may occur depending on the timing at the time of switching. Therefore, either set a range where both the switching elements Q2 and Q3 are turned ON, or When the feedback control switching means 13 in FIG. 8 selects the detection value of the voltage feedback control circuit 12, the dimming control unit 15 refers to the detection value of the current feedback control circuit 11 at the same time to eliminate malfunctions and flickers. Such control can also be performed. As a conceptual diagram, FIG. 12 shows that there may be a range in which constant current control and constant voltage control are performed simultaneously.

本実施形態では、電流フィードバック制御回路11、電圧フィードバック制御回路12の回路方式として、図9、図10の構成を例示して説明したが、定電流制御、定電圧制御を行う回路方式であれば特に限定したものではない。また、DC−DCコンバータ10はフライバック型に限らず、フォワード型でも構わない。   In the present embodiment, the configuration of FIGS. 9 and 10 has been described as the circuit system of the current feedback control circuit 11 and the voltage feedback control circuit 12, but any circuit system that performs constant current control and constant voltage control may be used. There is no particular limitation. The DC-DC converter 10 is not limited to the flyback type, and may be a forward type.

本発明の実施形態1の構成を示すブロック回路図である。 It is a block circuit diagram which shows the structure of Embodiment 1 of this invention. 本発明の実施形態1の動作を示す調光特性図である。 It is a light control characteristic figure which shows operation | movement of Embodiment 1 of this invention. 本発明の実施形態1の負荷特性を示す特性図である。 It is a characteristic view which shows the load characteristic of Embodiment 1 of this invention. 本発明の実施形態2の構成を示すブロック回路図である。 It is a block circuit diagram which shows the structure of Embodiment 2 of this invention. 本発明の実施形態2の動作を示す調光特性図である。 It is a light control characteristic figure which shows operation | movement of Embodiment 2 of this invention. 本発明の実施形態2の動作を示す調光特性図である。 It is a light control characteristic figure which shows operation | movement of Embodiment 2 of this invention. 本発明の実施形態2の動作を示す調光特性図である。 It is a light control characteristic figure which shows operation | movement of Embodiment 2 of this invention. 本発明の実施形態3の全体構成を示す回路図である。 It is a circuit diagram which shows the whole structure of Embodiment 3 of this invention. 本発明の実施形態3の要部構成を示す回路図である。 It is a circuit diagram which shows the principal part structure of Embodiment 3 of this invention. 本発明の実施形態3の要部構成を示す回路図である。 It is a circuit diagram which shows the principal part structure of Embodiment 3 of this invention. 本発明の実施形態3の要部構成を示す回路図である。 It is a circuit diagram which shows the principal part structure of Embodiment 3 of this invention. 本発明の実施形態3の動作を示す説明図である。 It is explanatory drawing which shows operation | movement of Embodiment 3 of this invention.

1 調光器
2 電源
3 LED点灯装置
4 LED負荷
5 マイコン
6 定電流回路
Q1 トランジスタ
DESCRIPTION OF SYMBOLS 1 Dimmer 2 Power supply 3 LED lighting device 4 LED load 5 Microcomputer 6 Constant current circuit Q1 Transistor

Claims (1)

  1. LED負荷に流れる電流の大きさを可変制御する電流調整手段と、
    LED負荷に流れる電流を断続制御するスイッチ手段と、
    調光器から出力される調光信号を受けて前記電流調整手段と前記スイッチ手段を制御する調光制御手段とを備えるLED調光装置であって、
    前記調光制御手段は、
    前記調光器から出力される調光信号が所定のレベルよりも高輝度側の場合、LED負荷に流れる電流を連続電流とし、流れる電流の大きさによりLED負荷を調光し、
    前記調光器から出力される調光信号が前記所定のレベルよりも低輝度側の場合、LED負荷に流れる電流をパルス状にして、その波形の平均値を変化させることによりLED負荷を調光し、
    前記所定のレベルは、LED負荷のV−I特性において、電流変化に対する電圧変化の割合を求め、該割合が、定格電流を流したときに比べて3〜5倍となる範囲に設定したことを特徴とするLED調光装置。 The predetermined level was set in a range in which the ratio of the voltage change to the current change was obtained in the VI characteristics of the LED load , and the ratio was set to a range of 3 to 5 times that when the rated current was applied. A featured LED dimming device. Current adjusting means for variably controlling the magnitude of the current flowing through the LED load; Current adjusting means for variably controlling the magnitude of the current flowing through the LED load;
    Switch means for intermittently controlling the current flowing through the LED load; Switch means for intermittently controlling the current flowing through the LED load;
    An LED dimming device comprising a dimming control means for receiving the dimming signal output from the dimmer and controlling the current adjusting means and the switch means, An LED dimming device comprising a dimming control means for receiving the dimming signal output from the dimmer and controlling the current adjusting means and the switch means,
    The dimming control means includes The dimming control means includes
    When the dimming signal output from the dimmer is on the higher luminance side than the predetermined level, the current flowing through the LED load is set as a continuous current, and the LED load is dimmed according to the magnitude of the flowing current, When the dimming signal output from the dimmer is on the higher luminance side than the predetermined level, the current flowing through the LED load is set as a continuous current, and the LED load is dimmed according to the magnitude of the flowing current,
    When the dimming signal output from the dimmer is on the lower luminance side than the predetermined level, the LED load is dimmed by changing the average value of the waveform by pulsing the current flowing through the LED load. And When the dimming signal output from the dimmer is on the lower luminance side than the predetermined level, the LED load is dimmed by changing the average value of the waveform by pulsing the current flowing through the LED load.
    The predetermined level is obtained by obtaining a ratio of voltage change with respect to current change in the VI characteristic of the LED load , and setting the ratio within a range of 3 to 5 times that when a rated current is passed. LED dimming device characterized. The predetermined level is obtained by obtaining a ratio of voltage change with respect to current change in the VI characteristic of the LED load , and setting the ratio within a range of 3 to 5 times that when a rated current is passed. LED dimming device characterized. ..
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