JP5881346B2 - Constant current circuit and LED driving constant current circuit - Google Patents
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この発明は、定電流回路及び発光ダイオード駆動定電流回路に関するものである。 The present invention relates to a constant current circuit and a light emitting diode driving constant current circuit.
周囲温度特性と点灯時間特性とを補償する定電流回路を提供する試みがあった。 There have been attempts to provide a constant current circuit that compensates for ambient temperature characteristics and lighting time characteristics.
この発明は、周囲温度特性を補償する定電流回路を提供する。また、この発明は、点灯時間特性を補償する定電流回路を提供する。 The present invention provides a constant current circuit that compensates for ambient temperature characteristics. The present invention also provides a constant current circuit that compensates for lighting time characteristics.
この発明に係る定電流回路は、負荷回路に対して電力を供給する定電流回路において、
ベースとエミッタとコレクタとを有するトランジスタＱ１と、
一端がベースと接続され、他端がエミッタと接続された抵抗Ｒ１と、
上記抵抗と並列に接続され、温度により抵抗値が変化する第１サーミスタＲｔｈ１と、
上記抵抗と並列に接続され、温度により抵抗値が変化する第２サーミスタＲｔｈ２と
を備え、
トランジスタＱ１は、摂氏−２０度〜＋５０度で、低温ではＶＥＢ電圧が低く、高温ではＶＥＢ電圧が高くなる特性を有し、
上記第１サーミスタＲｔｈ１は、摂氏−２０度〜＋５０度で、低温ほど抵抗が大きく、
上記第２サーミスタＲｔｈ２は、抵抗Ｒ１と第１サーミスタＲｔｈ１との２素子の摂氏＋２０度における合成抵抗の値に対する上記２素子の摂氏−２０度〜＋５０度における合成抵抗の値の変化量よりも、抵抗Ｒ１と第１サーミスタＲｔｈ１と第２サーミスタＲｔｈ２との３素子の摂氏＋２０度における合成抵抗の値に対する上記３素子の摂氏−２０度〜＋５０度における合成抵抗の値の温度変化量が、摂氏−２０度〜＋５０度において小さくなるような特性を有し、
上記３素子の摂氏−２０度〜＋５０度における合成抵抗の値が、低温時大きく、高温時小さくなるようにすることを特徴とする。
A constant current circuit according to the present invention is a constant current circuit that supplies power to a load circuit.
A transistor Q1 having a base, an emitter and a collector;
A resistor R1 having one end connected to the base and the other end connected to the emitter;
A first thermistor Rth1 connected in parallel with the resistor, the resistance value of which varies with temperature;
A second thermistor Rth2 connected in parallel with the resistor, the resistance value of which varies with temperature,
The transistor Q1 has a characteristic in which the VEB voltage is low at a low temperature and the VEB voltage is high at a high temperature at −20 degrees to +50 degrees Celsius.
The first thermistor Rth1 is -20 degrees to +50 degrees Celsius, and the resistance increases as the temperature decreases.
The second thermistor Rth2 is more than the amount of change in the value of the combined resistance at −20 degrees to +50 degrees Celsius of the two elements with respect to the combined resistance value of the resistance R1 and the first thermistor Rth1 at +20 degrees Celsius. The temperature change amount of the combined resistance value between −20 degrees to +50 degrees Celsius of the above three elements with respect to the combined resistance value at +20 degrees Celsius of the three elements of the resistor R1, the first thermistor Rth1 and the second thermistor Rth2 is −degree Celsius−. have a characteristic smaller at 20 degrees to + 50 degrees,
The combined resistance value of the three elements at -20 degrees to +50 degrees Celsius is large at a low temperature and small at a high temperature .
この発明は、第１サーミスタＲｔｈ１と第２サーミスタＲｔｈ２とにより、周囲温度特性を補償する定電流回路を提供する。また、この発明は、第３サーミスタＲｔｈ３により、点灯時間特性を補償する定電流回路を提供する。 The present invention provides a constant current circuit that compensates for ambient temperature characteristics using a first thermistor Rth1 and a second thermistor Rth2. The present invention also provides a constant current circuit that compensates the lighting time characteristic by the third thermistor Rth3.
実施の形態１．
図１は、ＬＥＤ（発光ダイオード）駆動用定電流回路を示す図である。
トランジスタＱ１は、ベースとエミッタとコレクタとを有する。トランジスタＱ２は、ベースとエミッタとコレクタとを有する。電源ＶＣＣは、トランジスタＱ１のエミッタと接続されている。
FIG. 1 is a diagram showing a constant current circuit for driving an LED (light emitting diode).
Transistor Q1 has a base, an emitter, and a collector. Transistor Q2 has a base, an emitter, and a collector. The power supply VCC is connected to the emitter of the transistor Q1.
抵抗Ｒ１は、一端がトランジスタＱ１のベースと接続され、他端がトランジスタＱ１のエミッタと接続されている。トランジスタＱ１のベースは、トランジスタＱ２のエミッタと接続されている。トランジスタＱ１のコレクタは、トランジスタＱ２のベースと接続されている。抵抗Ｒ２は、一端がトランジスタＱ２のベースと接続され、他端が接地ＧＮＤに接続されている。 One end of the resistor R1 is connected to the base of the transistor Q1, and the other end is connected to the emitter of the transistor Q1. The base of the transistor Q1 is connected to the emitter of the transistor Q2. The collector of the transistor Q1 is connected to the base of the transistor Q2. The resistor R2 has one end connected to the base of the transistor Q2 and the other end connected to the ground GND.
ＬＥＤ１，２，３，４，５，６が直列に接続されている。発光ダイオードは、発光直後から次第に暗くなり所定時間後に一定の明るさになる特性を有している。ＬＥＤ１は、トランジスタＱ２のコレクタと接続されている。ＬＥＤ６は、接地ＧＮＤに接続されている。
図１は、負荷回路に対して電力を供給する定電流回路を示している。トランジスタＱ１と抵抗Ｒ１により、定電流回路を構成している。トランジスタＱ２と抵抗Ｒ２とＬＥＤ１，２，３，４，５，６とにより、負荷回路を構成している。
FIG. 1 shows a constant current circuit that supplies power to a load circuit. The transistor Q1 and the resistor R1 constitute a constant current circuit. A load circuit is configured by the transistor Q2, the resistor R2, and the
図２は、図１のＬＥＤ駆動用定電流回路の周囲温度による明るさの変化量を示す図である。ここで、周囲温度とはＬＥＤモジュールが存在している大気温度（室内温度）である。 FIG. 2 is a diagram showing the amount of change in brightness according to the ambient temperature of the LED driving constant current circuit of FIG. Here, the ambient temperature is the atmospheric temperature (room temperature) where the LED module is present.
摂氏＋２０度（常温）の時の明るさを１００％の明るさとすると、ＬＥＤの一般的な動作周囲温度範囲である摂氏−２０度〜＋５０度で、明るさが約１１４％〜９０％の範囲で変化する。
摂氏−２０度の時は、常温（摂氏＋２０度）の時と比べて約１４％明るくなる。摂氏＋５０度の時は、常温（摂氏＋２０度）の時と比べて約１０％暗くなる。
If the brightness at +20 degrees Celsius (room temperature) is 100%, the general operating ambient temperature range of the LED is -20 degrees to +50 degrees Celsius, and the brightness is in the range of about 114% to 90%. It changes with.
When the temperature is -20 degrees Celsius, it is about 14% brighter than when the temperature is normal (20 degrees Celsius). When it is +50 degrees Celsius, it is about 10% darker than when it is normal temperature (+20 degrees Celsius).
このように、図１のＬＥＤ駆動用定電流回路では、図２に示すように、周囲温度の変化に伴い、ＬＥＤの明るさも変化する。それは、トランジスタＱ１の温度特性によるものであり、電圧の変動により、電流値が変化するため、全光束（明るさ）が変化するためである。 As described above, in the LED driving constant current circuit shown in FIG. 1, the brightness of the LED also changes as the ambient temperature changes, as shown in FIG. This is due to the temperature characteristics of the transistor Q1, and because the current value changes due to voltage fluctuation, the total luminous flux (brightness) changes.
具体的には、トランジスタのＶＥＢ電圧は、温度で変化する。低温ではＶＥＢ電圧が低く、高温ではＶＥＢ電圧が高くなる。固定抵抗Ｒのみでは、低温時は電流が多くながれ、高温では電流がすくなくなるという現象になり、結果として、周囲温度の変化に伴い、ＬＥＤの明るさも変化する。 Specifically, the VEB voltage of the transistor changes with temperature. At low temperatures, the VEB voltage is low, and at high temperatures, the VEB voltage is high. With only the fixed resistor R, the current increases at a low temperature, and the current decreases at a high temperature. As a result, the brightness of the LED also changes as the ambient temperature changes.
さらに、図３は、図１のＬＥＤ駆動用定電流回路の点灯時間による明るさの変化量を示す図である。点灯後３０分後の明るさを１００％の明るさとすると、０分〜３０分で、明るさが約１０８％〜１００％の範囲で変化する。
点灯直後は、１０８％程度の明るさとなり、点灯後３０分で１００％となる。
このように、図１のＬＥＤ駆動用定電流回路では、図３に示すように、ＬＥＤの特性上、点灯直後が明るく時間とともに暗くなり、約３０分後に安定する。
Furthermore, FIG. 3 is a diagram showing the amount of change in brightness depending on the lighting time of the LED driving constant current circuit of FIG. Assuming that the
Immediately after lighting, the brightness is about 108%, and becomes 100% 30 minutes after lighting.
As described above, in the LED driving constant current circuit of FIG. 1, as shown in FIG. 3, due to the characteristics of the LED, the state immediately after lighting is bright and dark with time, and is stabilized after about 30 minutes.
図４は、抵抗Ｒ１とサーミスタＲｔｈ１によるＬＥＤ駆動用定電流回路を示す図である。
図１に対して、サーミスタＲｔｈ１（第１サーミスタＲｔｈ１）が追加されている。サーミスタＲｔｈ１は、抵抗Ｒ１と並列に接続され、一端がトランジスタＱ１のベースと接続され、他端がトランジスタＱ１のエミッタと接続されている。
FIG. 4 is a diagram illustrating an LED driving constant current circuit including a resistor R1 and a thermistor Rth1.
A thermistor Rth1 (first thermistor Rth1) is added to FIG. The thermistor Rth1 is connected in parallel with the resistor R1, one end is connected to the base of the transistor Q1, and the other end is connected to the emitter of the transistor Q1.
サーミスタＲｔｈ１は、温度により抵抗値が変化する温度補償サーミスタである。サーミスタＲｔｈ１は、低温ほど抵抗が大きく、高温ほど抵抗が小さくなる。 The thermistor Rth1 is a temperature compensation thermistor whose resistance value changes with temperature. The thermistor Rth1 has a higher resistance at lower temperatures and a lower resistance at higher temperatures.
図５は、図４のＬＥＤ駆動用定電流回路の周囲温度による明るさの変化量を示す図である。
摂氏＋２０度（常温）の時の明るさを１００％の明るさとすると、ＬＥＤの一般的な動作周囲温度範囲である摂氏−２０度〜＋５０度で、明るさが約１０７％〜９８％の範囲で変化する。
摂氏−２０度の時は、常温（摂氏＋２０度）の時と比べて約７％明るくなる。摂氏＋３０、＋４０、＋５０度の時は、常温（摂氏＋２０度）の時と比べて約１％又は約２％暗くなる。
FIG. 5 is a diagram showing the amount of change in brightness according to the ambient temperature of the LED driving constant current circuit of FIG.
When the brightness at +20 degrees Celsius (room temperature) is 100%, the general operating ambient temperature range of the LED is -20 degrees to +50 degrees Celsius, and the brightness is in the range of about 107% to 98%. It changes with.
When the temperature is -20 degrees Celsius, it is about 7% brighter than when the temperature is normal temperature (degrees Celsius +20 degrees). When the temperature is +30, +40, and +50 degrees Celsius, it is about 1% or about 2% darker than that at room temperature (+20 degrees Celsius).
このように、図４のＬＥＤ駆動用定電流回路では、図５に示すように、周囲温度の変化に伴い、ＬＥＤの明るさも変化するが、サーミスタＲｔｈ１を追加することにより周囲温度の変化による、明るさの変化を補正できる。
その理由は、抵抗Ｒ１とサーミスタＲｔｈ１との並列接続による合成抵抗の変動が温度変化に対して抵抗Ｒ１だけの場合に比べて小さくなるからである。換言すれば、サーミスタＲｔｈ１は、抵抗Ｒ１との合成抵抗が温度変化に対して変化量が小さくなるような特性を有するものを使用すればよい。
As described above, in the LED driving constant current circuit of FIG. 4, the brightness of the LED also changes as the ambient temperature changes as shown in FIG. 5, but by adding the thermistor Rth1, the ambient temperature changes. The change in brightness can be corrected.
The reason is that the fluctuation of the combined resistance due to the parallel connection of the resistor R1 and the thermistor Rth1 is smaller than the case of only the resistor R1 with respect to the temperature change. In other words, the thermistor Rth1 may have a characteristic that the combined resistance with the resistor R1 has such a characteristic that the amount of change with respect to a temperature change becomes small.
具体的には、摂氏−２０度〜摂氏＋５０度で、サーミスタＲｔｈ１は低温ほど抵抗が大きいものを選定し、抵抗ＲとサーミスタＲｔｈ１の２素子の合成抵抗が低温時大きく、高温時小さくなるようにする事により温度補償する。しかし、完全に温度補償されるものではない。 Specifically, a thermistor Rth1 having a resistance of -20 degrees Celsius to +50 degrees Celsius and having a higher resistance at a lower temperature is selected so that the combined resistance of the two elements of the resistor R and the thermistor Rth1 is large at a low temperature and small at a high temperature. Temperature compensation. However, it is not completely temperature compensated.
図６は、図４のＬＥＤ駆動用定電流回路の点灯時間による明るさの変化量を示す図である。図６に示すように、図４のＬＥＤ駆動用定電流回路では、点灯時間による明るさの変化は補正できない。 FIG. 6 is a diagram showing the amount of change in brightness depending on the lighting time of the LED driving constant current circuit of FIG. As shown in FIG. 6, the LED driving constant current circuit of FIG. 4 cannot correct the change in brightness due to the lighting time.
図７は、抵抗Ｒ１とサーミスタＲｔｈ１・Ｒｔｈ２・Ｒｔｈ３によるＬＥＤ駆動用定電流回路を示す図である。
図４に対して、サーミスタＲｔｈ２（第２サーミスタＲｔｈ２）とサーミスタＲｔｈ３（第３サーミスタＲｔｈ３）とが、追加されている。
FIG. 7 is a diagram illustrating an LED driving constant current circuit including a resistor R1 and thermistors Rth1, Rth2, and Rth3.
4, a thermistor Rth2 (second thermistor Rth2) and a thermistor Rth3 (third thermistor Rth3) are added.
サーミスタＲｔｈ２は、抵抗Ｒ１とサーミスタＲｔｈ１とに並列に接続され、一端がトランジスタＱ１のベースと接続され、他端がトランジスタＱ１のエミッタと接続されている。サーミスタＲｔｈ２を並列に設置し、合成抵抗を細やかに設定できるようにする。サーミスタＲｔｈ２の抵抗値も摂氏−２０度〜摂氏＋５０度で変化するものではあるが、低温ほど抵抗が大きいとは限らない。 The thermistor Rth2 is connected in parallel to the resistor R1 and the thermistor Rth1, one end is connected to the base of the transistor Q1, and the other end is connected to the emitter of the transistor Q1. The thermistor Rth2 is installed in parallel so that the combined resistance can be set finely. The resistance value of the thermistor Rth2 also changes between −20 degrees Celsius and +50 degrees Celsius, but the resistance is not always greater at lower temperatures.
サーミスタＲｔｈ２は、温度により抵抗値が変化する温度補償サーミスタである。
サーミスタＲｔｈ２は、抵抗Ｒ１とサーミスタＲｔｈ１との２素子の合成抵抗の値よりも、抵抗Ｒ１とサーミスタＲｔｈ１とサーミスタＲｔｈ２との３素子の合成抵抗の値が温度変化に対して一定値に近づくようになるような特性を有する。
サーミスタＲｔｈ２は、抵抗Ｒ１とサーミスタＲｔｈ１の温度変化に対する合成抵抗値の値により、追加されるものである。したがって、サーミスタＲｔｈ２は、低温ほど抵抗が大きく、高温ほど抵抗が小さくなる特性を有する場合もあるし、逆に、低温ほど抵抗が小さく、高温ほど抵抗が大きくなる特性を有する場合もある。
The thermistor Rth2 is a temperature compensation thermistor whose resistance value changes with temperature.
The thermistor Rth2 is such that the combined resistance value of the three elements R1 and thermistor Rth1 and thermistor Rth2 approaches a constant value with respect to the temperature change, rather than the combined resistance value of the two elements R1 and thermistor Rth1. It has the characteristic which becomes.
The thermistor Rth2 is added depending on the value of the combined resistance value with respect to the temperature change of the resistor R1 and the thermistor Rth1. Therefore, the thermistor Rth2 may have a characteristic that the resistance is higher as the temperature is lower and the resistance is lower as the temperature is higher, and conversely, the resistance is lower as the temperature is lower and the resistance is higher as the temperature is higher.
サーミスタＲｔｈ３は、抵抗Ｒ１とサーミスタＲｔｈ１とサーミスタＲｔｈ２とに直列に接続され、一端が抵抗Ｒ１とサーミスタＲｔｈ１とサーミスタＲｔｈ２と接続され、他端がトランジスタＱ１のエミッタと接続されている。 The thermistor Rth3 is connected in series to the resistor R1, the thermistor Rth1, and the thermistor Rth2, one end is connected to the resistor R1, the thermistor Rth1, and the thermistor Rth2, and the other end is connected to the emitter of the transistor Q1.
サーミスタＲｔｈ３は、温度により抵抗値が変化する温度補償サーミスタである。
サーミスタＲｔｈ３は、時間経過によって生じる定電流回路の抵抗値の変化あるいは負荷回路の抵抗値の変化を相殺する特性を有する。サーミスタＲｔｈ３は、摂氏−２０度〜＋５０度で、低温ほど抵抗が大きい。すなわち、サーミスタＲｔｈ３は低温時は抵抗が大きく、高温になると抵抗が低くなるものを選定する。
点灯直後はサーミスタＲｔｈ３の抵抗が大きく、ＬＥＤに流れる電流がすくないが、点灯によるＬＥＤの発熱でサーミスタＲｔｈ３は抵抗が低くなるため、電流は徐々に大きくなっていく。
The thermistor Rth3 is a temperature compensated thermistor whose resistance value changes with temperature.
The thermistor Rth3 has a characteristic that cancels out the change in the resistance value of the constant current circuit or the change in the resistance value of the load circuit that occurs over time. The thermistor Rth3 is -20 degrees to +50 degrees Celsius, and the resistance is higher at lower temperatures. That is, the thermistor Rth3 is selected to have a large resistance at low temperatures and a low resistance at high temperatures.
Immediately after the lighting, the resistance of the thermistor Rth3 is large, and the current flowing through the LED is not great. However, the resistance of the thermistor Rth3 decreases due to the heat generation of the LED due to lighting, and the current gradually increases.
サーミスタＲｔｈ３は、抵抗Ｒ１とサーミスタＲｔｈ１とサーミスタＲｔｈ２との３素子の並列接続の合成抵抗とサーミスタＲｔｈ３の抵抗との直列接続の合成抵抗（４素子の合成抵抗）を、発光直後から次第に小さくし前記所定時間後に一定に近づける特性を有する。ＬＥＤは点灯直後が明るく、段々暗くなり、３０分程度で安定するという特性を有している。このＬＥＤの特性（負荷回路の特性）とサーミスタＲｔｈ３の特性とがあわさり、結果的に、点灯直後と３０分後の明るさが、ほぼ一定となる。
定電流回路の電流を決定する抵抗値は、抵抗Ｒ１とサーミスタＲｔｈ１とサーミスタＲｔｈ２の並列接続による合成抵抗に対してサーミスタＲｔｈ３の抵抗値を加算した値となる。
The thermistor Rth3 gradually reduces the combined resistance (four-element combined resistance) of the series connection of the resistor R1, the thermistor Rth1 and the thermistor Rth2 in parallel connection and the resistance of the thermistor Rth3 immediately after light emission. It has the characteristic of approaching a constant after a predetermined time. The LED has a characteristic that it is bright immediately after lighting, becomes gradually darker, and stabilizes in about 30 minutes. The characteristics of the LED (load circuit characteristics) and the thermistor Rth3 are combined, and as a result, the brightness immediately after lighting and after 30 minutes is substantially constant.
The resistance value that determines the current of the constant current circuit is a value obtained by adding the resistance value of the thermistor Rth3 to the combined resistance by the parallel connection of the resistor R1, the thermistor Rth1, and the thermistor Rth2.
図８は、図７のＬＥＤ駆動用定電流回路の周囲温度による明るさの変化量を示す図である。
摂氏＋２０度（常温）の時の明るさを１００％の明るさとすると、ＬＥＤの一般的な動作周囲温度範囲である摂氏−２０度〜＋５０度で、明るさが約１０３％〜１００％の範囲で変化する。
摂氏−２０度の時は、常温（摂氏＋２０度）の時と比べて約３％明るくなる。摂氏＋１０〜摂氏＋４０度の時は、常温（摂氏＋２０度）の時と同じ明るさになる。摂氏＋５０度の時は、常温（摂氏＋２０度）の時と比べて１％明るくなる。
FIG. 8 is a diagram showing the amount of change in brightness according to the ambient temperature of the LED driving constant current circuit of FIG.
If the brightness at +20 degrees Celsius (room temperature) is 100%, the general operating ambient temperature range of the LED is -20 degrees to +50 degrees Celsius, and the brightness is in the range of about 103% to 100%. It changes with.
When the temperature is -20 degrees Celsius, it is about 3% brighter than when the temperature is normal (20 degrees Celsius). When the temperature is +10 to +40 degrees Celsius, the brightness is the same as that at normal temperature (+20 degrees Celsius). When it is +50 degrees Celsius, it is 1% brighter than when it is at room temperature (+20 degrees Celsius).
このように、図７のＬＥＤ駆動用定電流回路では、図８に示すように、周囲温度の変化に伴い、ＬＥＤの明るさも変化するが、サーミスタＲｔｈ１とサーミスタＲｔｈ２とを追加することにより周囲温度の変化による、明るさの変化をさらに補正できる。
その理由は、抵抗Ｒ１とサーミスタＲｔｈ１とサーミスタＲｔｈ２との並列接続による合成抵抗の変動が温度変化に対して抵抗Ｒ１とサーミスタＲｔｈ１とだけの場合に比べて小さくなるからである。
Thus, in the LED driving constant current circuit of FIG. 7, as shown in FIG. 8, the brightness of the LED changes with the change of the ambient temperature, but the ambient temperature is increased by adding the thermistor Rth1 and the thermistor Rth2. It is possible to further correct the change in brightness due to the change in.
This is because the fluctuation of the combined resistance due to the parallel connection of the resistor R1, the thermistor Rth1, and the thermistor Rth2 is smaller than the case of only the resistor R1 and the thermistor Rth1 with respect to the temperature change.
さらに、図９は、図７のＬＥＤ駆動用定電流回路の点灯時間による明るさの変化量を示す図である。点灯後３０分後の明るさを１００％の明るさとすると、０分〜３０分で、明るさが約１０３％〜１００％の範囲で変化する。
点灯直後は、１０３％程度の明るさとなり、点灯後６分で１００％となる。
このように、図７のＬＥＤ駆動用定電流回路では、図９に示すように、ＬＥＤの特性上、点灯直後が明るく時間とともに暗くなり、約６分後に安定する。
サーミスタＲｔｈ３を追加する事により、点灯時間による、明るさの変化も補正する事ができる。
Furthermore, FIG. 9 is a diagram showing the amount of change in brightness depending on the lighting time of the LED driving constant current circuit of FIG. Assuming that the
Immediately after lighting, the brightness is about 103%, and becomes 100% in 6 minutes after lighting.
As described above, in the LED driving constant current circuit of FIG. 7, as shown in FIG. 9, due to the characteristics of the LED, immediately after lighting, it becomes brighter and darker with time and becomes stable after about 6 minutes.
By adding the thermistor Rth3, it is possible to correct the change in brightness due to the lighting time.
実施の形態２．
実施の形態２では、実施の形態１と異なる点について述べる。
図１０は、図７から、サーミスタＲｔｈ３を削除したものである。
図１０のＬＥＤ駆動用定電流回路では、図８に示したように、周囲温度の変化による、明るさの変化を補正できる。しかし、サーミスタＲｔｈ３がないので点灯時間による、明るさの変化は、補正する事ができない。
In the second embodiment, differences from the first embodiment will be described.
FIG. 10 is obtained by deleting the thermistor Rth3 from FIG.
In the constant current circuit for LED driving in FIG. 10, as shown in FIG. 8, it is possible to correct a change in brightness due to a change in ambient temperature. However, since there is no thermistor Rth3, the change in brightness due to the lighting time cannot be corrected.
図１１は、図４の抵抗Ｒ１を除し、サーミスタＲｔｈ１をサーミスタＲｔｈ４としたものである。サーミスタＲｔｈ４は、単体で、図２に示す周囲温度特性を補償する特性を有している。さらに、サーミスタＲｔｈ４は、単体で、図３に示す点灯時間特性を補償する特性を有している。
図１１のＬＥＤ駆動用定電流回路では、周囲温度の変化による、明るさの変化を補正できる。また、点灯時間による、明るさの変化を補正できる。ただし、サーミスタＲｔｈ４単体で周囲温度特性と点灯時間特性との両方を補償するために完全な補償が出来る可能性は少ない。
FIG. 11 is obtained by removing the resistor R1 of FIG. 4 and replacing the thermistor Rth1 with the thermistor Rth4. The thermistor Rth4 is a single body and has a characteristic for compensating the ambient temperature characteristic shown in FIG. Further, the thermistor Rth4 is a single unit and has a characteristic for compensating the lighting time characteristic shown in FIG.
The LED driving constant current circuit of FIG. 11 can correct a change in brightness due to a change in ambient temperature. Further, it is possible to correct the change in brightness due to the lighting time. However, since the thermistor Rth4 alone compensates for both the ambient temperature characteristic and the lighting time characteristic, there is little possibility of complete compensation.
図１２は、サーミスタＲｔｈ５と、サーミスタＲｔｈ６とを直列に接続したものである。サーミスタＲｔｈ５は、主として、図２に示す周囲温度特性を補償する特性を有している。さらに、サーミスタＲｔｈ６は、主として、図３に示す点灯時間特性を補償する特性を有している。
図１２のＬＥＤ駆動用定電流回路では、周囲温度の変化による、明るさの変化を補正できる。また、点灯時間による、明るさの変化を補正できる。ただし、サーミスタＲｔｈ５とサーミスタＲｔｈ６との抵抗値は、互いに、温度変化するので、相互作用があっても完全な補償を提供するために最適な特性を持つものが選択されなければならない。
FIG. 12 shows a thermistor Rth5 and a thermistor Rth6 connected in series. The thermistor Rth5 mainly has a characteristic for compensating the ambient temperature characteristic shown in FIG. Further, the thermistor Rth6 mainly has a characteristic for compensating the lighting time characteristic shown in FIG.
In the LED driving constant current circuit of FIG. 12, it is possible to correct a change in brightness due to a change in ambient temperature. Further, it is possible to correct the change in brightness due to the lighting time. However, since the resistance values of the thermistor Rth5 and thermistor Rth6 change in temperature with respect to each other, those having optimum characteristics must be selected in order to provide complete compensation even if there is an interaction.
実施の形態３．
ＬＥＤの数は、６個に限らず、１個以上あればよい。
トランジスタＱ１，Ｑ２の種類は、ＮＰ型でもＰＮ型でもよい。
負荷回路は、ＬＥＤを有していなくてもよく、その他の発光ランプを有する場合でもよい。また、発光ランプの回路以外でもよく、電動機、ロボットなどの回路でもよい。
負荷回路は、トランジスタＱ２、抵抗Ｒ２を有していなくてもよい。
Embodiment 3 FIG.
The number of LEDs is not limited to six and may be one or more.
The types of the transistors Q1 and Q2 may be NP type or PN type.
The load circuit may not have the LED, and may have another light emitting lamp. Further, it may be other than the circuit of the light emitting lamp, and may be a circuit of an electric motor or a robot.
The load circuit may not include the transistor Q2 and the resistor R2.
以上の実施の形態に係る定電流回路は、負荷回路に対して電力を供給する定電流回路において、 The constant current circuit according to the above embodiment is a constant current circuit that supplies power to a load circuit.
ベースとエミッタとコレクタとを有するトランジスタＱ１と、 A transistor Q1 having a base, an emitter and a collector;
一端がベースと接続され、他端がエミッタと接続された抵抗Ｒ１と、 A resistor R1 having one end connected to the base and the other end connected to the emitter;
上記抵抗と並列に接続され、温度により抵抗値が変化する第１サーミスタＲｔｈ１と、 A first thermistor Rth1 connected in parallel with the resistor, the resistance value of which varies with temperature;
上記抵抗と並列に接続され、温度により抵抗値が変化する第２サーミスタＲｔｈ２と A second thermistor Rth2 connected in parallel with the resistor, the resistance value of which varies with temperature;
を備えたことを特徴とする。It is provided with.
上記第１サーミスタＲｔｈ１は、低温ほど抵抗が大きく、 The first thermistor Rth1 has a higher resistance at lower temperatures,
上記第２サーミスタＲｔｈ２は、抵抗Ｒ１と第１サーミスタＲｔｈ１との２素子の合成抵抗の値よりも、抵抗Ｒ１と第１サーミスタＲｔｈ１と上記第２サーミスタＲｔｈ２との３素子の合成抵抗の値が一定値になるような特性を有することを特徴とする。 The second thermistor Rth2 has a constant value of the combined resistance of the three elements R1, R1 and Rth2, rather than the combined resistance of the two elements R1 and Rth1. It has a characteristic that becomes a value.
上記第１サーミスタＲｔｈ１は、摂氏−２０度〜＋５０度で、低温ほど抵抗が大きく、 The first thermistor Rth1 is -20 degrees to +50 degrees Celsius, and the resistance increases as the temperature decreases.
上記第２サーミスタＲｔｈ２は、摂氏−２０度〜＋５０度で、上記３素子の合成抵抗の値を上記２素子の合成抵抗の値よりも一定値に近づけることを特徴とする。 The second thermistor Rth2 is -20 degrees to +50 degrees Celsius, and is characterized in that the combined resistance value of the three elements is closer to a constant value than the combined resistance value of the two elements.
上記定電流回路は、さらに、上記エミッタと上記抵抗との間に上記抵抗と直列に接続され、温度により抵抗値が変化する第３サーミスタＲｔｈ３を備えたことを特徴とする。 The constant current circuit further includes a third thermistor Rth3 connected in series with the resistor between the emitter and the resistor, the resistance value of which varies with temperature.
上記第３サーミスタＲｔｈ３は、時間経過によって生じる負荷回路の変化を相殺する特性を有することを特徴とする。 The third thermistor Rth3 has a characteristic that cancels out a change in the load circuit caused by the passage of time.
また、発光ダイオード駆動定電流回路は、 In addition, the LED driving constant current circuit is
上記定電流回路と、 The constant current circuit;
上記定電流回路から電力の供給を受ける負荷回路とを備え、 A load circuit that receives power from the constant current circuit,
上記負荷回路は、 The load circuit is
トランジスタＱ１のコレクタに接続されたベースと、トランジスタＱ１のベースに接続されたエミッタと、コレクタとを有するトランジスタＱ２と、 A transistor Q2 having a base connected to the collector of the transistor Q1, an emitter connected to the base of the transistor Q1, and a collector;
トランジスタＱ２のコレクタに接続された発光ダイオードと A light emitting diode connected to the collector of transistor Q2;
を備えたことを特徴とする。It is provided with.
上記発光ダイオードは、発光直後から次第に暗くなり所定時間後に一定の明るさになる特性を有し、 The light emitting diode has a characteristic that it becomes darker immediately after light emission and becomes constant brightness after a predetermined time,
上記第３サーミスタＲｔｈ３は、摂氏−２０度〜＋５０度で、低温ほど抵抗が大きく、 The third thermistor Rth3 is −20 degrees to +50 degrees Celsius, and the resistance increases as the temperature decreases.
上記第３サーミスタＲｔｈ３は、上記３素子の合成抵抗と上記第３サーミスタＲｔｈ３との４素子の合成抵抗を、発光直後から次第に小さくし前記所定時間後に一定に近づける特性を有することを特徴とする。 The third thermistor Rth3 has a characteristic that the combined resistance of the four elements of the three elements and the third thermistor Rth3 is gradually decreased immediately after the light emission, and approaches a constant value after the predetermined time.
１，２，３，４，５，６ ＬＥＤ、Ｒｔｈ１，Ｒｔｈ２，Ｒｔｈ３，Ｒｔｈ４，Ｒｔｈ５，Ｒｔｈ６ サーミスタ、Ｑ１，Ｑ２ トランジスタ、Ｒ１，Ｒ２ 抵抗、ＧＮＤ 接地。 1, 2, 3, 4, 5, 6 LEDs, Rth1, Rth2, Rth3, Rth4, Rth5, Rth6 thermistors, Q1, Q2 transistors, R1, R2 resistors, GND ground.
Claims (8)
ベースとエミッタとコレクタとを有するトランジスタＱ１と、
一端がベースと接続され、他端がエミッタと接続された抵抗Ｒ１と、
上記抵抗Ｒ１と並列に接続され、温度により抵抗値が変化する第１サーミスタＲｔｈ１と、
上記抵抗Ｒ１と並列に接続され、温度により抵抗値が変化する第２サーミスタＲｔｈ２と、
を備え、
トランジスタＱ１は、摂氏−２０度〜＋５０度で、低温ではＶＥＢ電圧が低く、高温ではＶＥＢ電圧が高くなる特性を有し、
上記第１サーミスタＲｔｈ１は、摂氏−２０度〜＋５０度で、低温ほど抵抗が大きく、
上記第２サーミスタＲｔｈ２は、抵抗Ｒ１と第１サーミスタＲｔｈ１との２素子の摂氏＋２０度における合成抵抗の値に対する上記２素子の摂氏−２０度〜＋５０度における合成抵抗の値の変化量よりも、抵抗Ｒ１と第１サーミスタＲｔｈ１と第２サーミスタＲｔｈ２との３素子の摂氏＋２０度における合成抵抗の値に対する上記３素子の摂氏−２０度〜＋５０度における合成抵抗の値の温度変化量が、摂氏−２０度〜＋５０度において小さくなるような特性を有し、
上記３素子の摂氏−２０度〜＋５０度における合成抵抗の値が、低温時大きく、高温時小さくなるようにすることを特徴とする定電流回路。 In the constant current circuit that supplies power to the load circuit,
A transistor Q1 having a base, an emitter and a collector;
A resistor R1 having one end connected to the base and the other end connected to the emitter;
A first thermistor Rth1 connected in parallel with the resistor R1 and having a resistance value that varies with temperature;
A second thermistor Rth2 connected in parallel with the resistor R1 and having a resistance value varying with temperature;
With
The transistor Q1 has a characteristic in which the VEB voltage is low at a low temperature and the VEB voltage is high at a high temperature at −20 degrees to +50 degrees Celsius.
The first thermistor Rth1 is -20 degrees to +50 degrees Celsius, and the resistance increases as the temperature decreases.
The second thermistor Rth2 is more than the amount of change in the value of the combined resistance at −20 degrees to +50 degrees Celsius of the two elements with respect to the combined resistance value of the resistance R1 and the first thermistor Rth1 at +20 degrees Celsius. The temperature change amount of the combined resistance value between −20 degrees to +50 degrees Celsius of the above three elements with respect to the combined resistance value at +20 degrees Celsius of the three elements of the resistor R1, the first thermistor Rth1 and the second thermistor Rth2 is −degree Celsius−. have a characteristic smaller at 20 degrees to + 50 degrees,
A constant current circuit characterized in that the value of the combined resistance of the three elements at -20 to +50 degrees Celsius is large at low temperatures and small at high temperatures .
上記２素子の合成抵抗の値が、
低温ほど抵抗が大きく高温ほど抵抗が小さくなる特性を有する場合、
低温ほど抵抗が小さく高温ほど抵抗が大きくなる特性を有し、
上記２素子の合成抵抗の値が、
低温ほど抵抗が小さく高温ほど抵抗が大きくなる特性を有する場合、
低温ほど抵抗が大きく高温ほど抵抗が小さくなる特性を有することを特徴とする請求項１記載の定電流回路。 The second thermistor Rth2 is
The value of the combined resistance of the two elements is
When it has the characteristic that the resistance increases as the temperature decreases and the resistance decreases as the temperature increases,
It has the characteristic that the resistance decreases as the temperature decreases, and the resistance increases as the temperature increases.
The value of the combined resistance of the two elements is
When it has the characteristic that the resistance decreases as the temperature decreases and the resistance increases as the temperature increases,
2. The constant current circuit according to claim 1, wherein the constant current circuit has a characteristic that the resistance increases as the temperature decreases and the resistance decreases as the temperature increases.
ベースとエミッタとコレクタとを有するトランジスタＱ１と、
一端がベースと接続され、他端がエミッタと接続された抵抗Ｒ１と、
上記抵抗Ｒ１と並列に接続され、低温ほど抵抗が大きくなる第１サーミスタＲｔｈ１と、
上記抵抗Ｒ１と並列に接続され、温度により抵抗値が変化する第２サーミスタＲｔｈ２であって、抵抗Ｒ１と第１サーミスタＲｔｈ１との２素子の合成抵抗の値の温度変化量よりも、抵抗Ｒ１と第１サーミスタＲｔｈ１と第２サーミスタＲｔｈ２との３素子の合成抵抗の値の温度変化量が、摂氏−２０度〜＋５０度において小さくなるような特性を有する第２サーミスタＲｔｈ２と、
上記エミッタと上記抵抗との間に上記抵抗と直列に接続され、低温時は抵抗が大きく高温になると抵抗が小さくなる第３サーミスタＲｔｈ３を備え、
トランジスタＱ１は、摂氏−２０度〜＋５０度で、低温ではＶＥＢ電圧が低く、高温ではＶＥＢ電圧が高くなる特性を有し、
上記３素子の摂氏−２０度〜＋５０度における合成抵抗の値が、低温時大きく、高温時小さくなるようにすることを特徴とする定電流回路。 In the constant current circuit that supplies power to the load circuit,
A transistor Q1 having a base, an emitter and a collector;
A resistor R1 having one end connected to the base and the other end connected to the emitter;
A first thermistor Rth1, which is connected in parallel with the resistor R1, and whose resistance increases as the temperature decreases;
A second thermistor Rth2 connected in parallel with the resistor R1 and having a resistance value that changes with temperature. The resistance R1 is more than the amount of temperature change in the combined resistance value of the two elements of the resistor R1 and the first thermistor Rth1. A second thermistor Rth2 having such a characteristic that the temperature change amount of the combined resistance value of the three elements of the first thermistor Rth1 and the second thermistor Rth2 is reduced in the range of −20 degrees to +50 degrees Celsius;
A third thermistor Rth3 connected in series with the resistor between the emitter and the resistor, and having a large resistance at a low temperature and a small resistance at a high temperature,
The transistor Q1 has a characteristic in which the VEB voltage is low at a low temperature and the VEB voltage is high at a high temperature at −20 degrees to +50 degrees Celsius.
A constant current circuit characterized in that the value of the combined resistance of the three elements at -20 to +50 degrees Celsius is large at low temperatures and small at high temperatures .
上記定電流回路から電力の供給を受ける負荷回路とを備え、
上記負荷回路は、
トランジスタＱ１のコレクタに接続されたベースと、トランジスタＱ１のベースに接続されたエミッタと、コレクタとを有するトランジスタＱ２と、
トランジスタＱ２のコレクタに接続された発光ダイオードと
を備えたことを特徴とする発光ダイオード駆動定電流回路。 The constant current circuit according to claim 3 or 4,
A load circuit that receives power from the constant current circuit,
The load circuit is
A transistor Q2 having a base connected to the collector of the transistor Q1, an emitter connected to the base of the transistor Q1, and a collector;
A light emitting diode driving constant current circuit comprising: a light emitting diode connected to a collector of the transistor Q2.
上記第３サーミスタＲｔｈ３は、摂氏−２０度〜＋５０度で、低温ほど抵抗が大きく、
上記第３サーミスタＲｔｈ３は、抵抗Ｒ１と第１サーミスタＲｔｈ１と第２サーミスタＲｔｈ２との３素子の合成抵抗と上記第３サーミスタＲｔｈ３との４素子の合成抵抗を、発光直後から次第に小さくし前記所定時間後に一定に近づける特性を有することを特徴とする請求項６に記載の発光ダイオード駆動定電流回路。 The light emitting diode has a characteristic that it becomes darker immediately after light emission and becomes constant brightness after a predetermined time,
The third thermistor Rth3 is −20 degrees to +50 degrees Celsius, and the resistance increases as the temperature decreases.
The third thermistor Rth3 gradually decreases the combined resistance of the three elements of the resistor R1, the first thermistor Rth1, and the second thermistor Rth2 and the four elements of the third thermistor Rth3 immediately after light emission for the predetermined time. The light-emitting diode driving constant current circuit according to claim 6, which has a characteristic of approaching a constant value later.
ベースとエミッタとコレクタとを有するトランジスタＱ１と、
一端がベースと接続され、低温ほど抵抗が大きくなる特性を有することにより、周囲温度の変化によって生じる電流値の変化を補償するサーミスタＲｔｈ５と、
一端がエミッタと接続され、他端がサーミスタＲｔｈ５の他端と接続され、サーミスタＲｔｈ５とサーミスタＲｔｈ６との直列接続の合成抵抗値を通電直後から次第に小さくし所定時間後に一定に近づける特性を有することにより、時間経過によって生じる電流値の変化を補償するサーミスタＲｔｈ６と
を備えたことを特徴とする定電流回路。 In the constant current circuit that supplies power to the load circuit,
A transistor Q1 having a base, an emitter and a collector;
A thermistor Rth5 that compensates for a change in current value caused by a change in ambient temperature by having one end connected to the base and having a characteristic that resistance increases as the temperature decreases;
One end is connected to the emitter, the other end is connected to the other end of the thermistor Rth5, and the combined resistance value of the serial connection of the thermistor Rth5 and the thermistor Rth6 is gradually reduced immediately after energization, and has a characteristic of approaching a constant value after a predetermined time. , the constant current circuit, characterized in that a thermistor Rth6 to compensate for changes in the current value caused by the passage of time.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2011201505A JP5881346B2 (en) | 2011-09-15 | 2011-09-15 | Constant current circuit and LED driving constant current circuit |
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| Application Number | Priority Date | Filing Date | Title |
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| JP2011201505A JP5881346B2 (en) | 2011-09-15 | 2011-09-15 | Constant current circuit and LED driving constant current circuit |
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| JP2016017890A Division JP2016106418A (en) | 2016-02-02 | 2016-02-02 | Constant current circuit and light-emitting diode driving constant current circuit |
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| JP2013062462A JP2013062462A (en) | 2013-04-04 |
| JP5881346B2 true JP5881346B2 (en) | 2016-03-09 |
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Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| JP6924555B2 (en) * | 2015-03-02 | 2021-08-25 | 晶元光電股▲ふん▼有限公司Ｅｐｉｓｔａｒ Ｃｏｒｐｏｒａｔｉｏｎ | LED drive and related lighting system |
| USRE48798E1 (en) | 2015-03-02 | 2021-10-26 | Epistar Corporation | LED driver and illumination system related to the same |
| JP2017201719A (en) * | 2017-07-20 | 2017-11-09 | 三菱電機照明株式会社 | Constant current circuit and light-emitting diode-driving constant current circuit |
| JP7414738B2 (en) * | 2018-06-04 | 2024-01-16 | メルク パテント ゲゼルシャフト ミット ベシュレンクテル ハフツング | Calibration devices for optical detectors and setting devices for setting calibration points for calibration devices |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS50110255A (en) * | 1974-02-06 | 1975-08-30 | ||
| JPS585085U (en) * | 1981-06-30 | 1983-01-13 | トヨタ自動車株式会社 | Vehicle light emitting diode display circuit |
| JPS62114463U (en) * | 1986-01-09 | 1987-07-21 | ||
| JPH0921715A (en) * | 1995-07-05 | 1997-01-21 | Hokuriku Electric Ind Co Ltd | Temperature compensation circuit for sensor |
| JPH09199941A (en) * | 1996-01-16 | 1997-07-31 | Toyo Commun Equip Co Ltd | Temperature compensated crystal oscillator |
| JPH09283305A (en) * | 1996-04-11 | 1997-10-31 | Murata Mfg Co Ltd | Thermistor and method for adjusting resistance value of thermistor |
| JP3915147B2 (en) * | 1996-09-25 | 2007-05-16 | 松下電器産業株式会社 | Gain adjustment circuit and frequency conversion circuit |
| JP2006100975A (en) * | 2004-09-28 | 2006-04-13 | Mitsubishi Electric Corp | Wireless communication apparatus |
| JP5552813B2 (en) * | 2010-01-06 | 2014-07-16 | 富士通株式会社 | Current limiting circuit and electronic device |
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| JP2013062462A (en) | 2013-04-04 |
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