JPS5915392B2 - Light emitting diode drive circuit - Google Patents
Light emitting diode drive circuitInfo
- Publication number
- JPS5915392B2 JPS5915392B2 JP52135347A JP13534777A JPS5915392B2 JP S5915392 B2 JPS5915392 B2 JP S5915392B2 JP 52135347 A JP52135347 A JP 52135347A JP 13534777 A JP13534777 A JP 13534777A JP S5915392 B2 JPS5915392 B2 JP S5915392B2
- Authority
- JP
- Japan
- Prior art keywords
- light emitting
- emitting diode
- capacitor
- voltage
- resistor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 239000003990 capacitor Substances 0.000 claims description 20
- 230000010355 oscillation Effects 0.000 description 12
- 238000010586 diagram Methods 0.000 description 9
- 230000002457 bidirectional effect Effects 0.000 description 6
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 3
- 229910052710 silicon Inorganic materials 0.000 description 3
- 239000010703 silicon Substances 0.000 description 3
Classifications
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
- H05B45/30—Driver circuits
- H05B45/37—Converter circuits
- H05B45/3725—Switched mode power supply [SMPS]
Landscapes
- Circuit Arrangement For Electric Light Sources In General (AREA)
- Led Devices (AREA)
- Photo Coupler, Interrupter, Optical-To-Optical Conversion Devices (AREA)
Description
【発明の詳細な説明】
この発明は、光電スイッチなどに使用される発光ダイオ
ードの駆動回路に関するものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a driving circuit for a light emitting diode used in a photoelectric switch or the like.
従来、たとえばパルス変調光型の光電スイッチでは、発
光ダイオードとフォトトランジスタやフォトダイオード
などの受光素子との間でパルス光の授受を行なつており
、このパルスを発生させるため、従来第５図に示すよう
に、コンデンサＣと抵抗器Ｒ９からなる充電回路を直流
電源ＶｃＶＣ接続し、このコンデンサＣと並列に双方向
性スイッチング素子ｓ、発光ダイオードＤおよび抵抗器
Ｒ１からなる直列回路を接続して発光ダイオードの駆動
回路を構成し、上記コンデンサＣの充放電・ のくり返
し、すなわち、コンデンサＣが充電され、この電圧が双
方向性スイッチング素子ｓのプレーグオーバ電圧に達す
ると放電し、再び充電を開始することによつて、第６図
に示すようなし張発振を行なわせている。ｏ ところが
、上記の回路では、直流電源Ｖｃの電圧が下りすぎると
、コンデンサＣの充電電圧が、第Ｔ図の特性図に示す双
方向性スイッチング素子ｓのプレーグオーバ電圧ＶＢＯ
まで上昇せず、コンデンサＣは、充放電を行なうことが
なく、し張振を１５得ることができない。Conventionally, for example, in a pulse modulation light type photoelectric switch, pulsed light is exchanged between a light emitting diode and a light receiving element such as a phototransistor or photodiode. As shown, a charging circuit consisting of a capacitor C and a resistor R9 is connected to a DC power source VcVC, and a series circuit consisting of a bidirectional switching element s, a light emitting diode D and a resistor R1 is connected in parallel with the capacitor C to emit light. A diode drive circuit is configured, and the capacitor C is charged and discharged repeatedly, that is, the capacitor C is charged, and when this voltage reaches the pregover voltage of the bidirectional switching element s, it is discharged and starts charging again. This causes tensile oscillation as shown in FIG. o However, in the above circuit, if the voltage of the DC power supply Vc drops too much, the charging voltage of the capacitor C will decrease to the pregoverning voltage VBO of the bidirectional switching element s shown in the characteristic diagram of FIG.
Therefore, the capacitor C is not charged or discharged and cannot obtain a tension of 15%.
逆に、直流電源Ｖｃの電圧が上りすぎると、コンデンサ
Ｃの放電電流が、第７図に示す双方向スイッチング素子
ｓの保持電流ＩＨ以下にならず通電状態を持続し、この
場合も、し張発振を得ることができず、発光ダイオード
を２０駆動することができない。しかも、双方向性スイ
ッチング素子ｓは、第□図の特性図のように、上記プレ
ーグオーバ電流ＩＢｏと上記保持電流ＩＨとの差△Ｉが
非常に盛さい−め、し張発振を得るための直流電源Ｖｃ
の発振可能な電圧範囲は非常２５に狭く、ある値以上変
動するとし張発振が停止してしまう。まπ、たとえ直流
電源Ｖｃの電圧が発振可能範囲内にあるとしても、電源
電圧の変動が生ずると発振周期は、
Ｔ＝Ｒ９・ Ｃｔｎ（）
３０ＶＣ−ＶＢＯ
によつて、第６図の仮想線に示すように変化してしまい
、正常な発光ダイオードの駆動ができない。Conversely, if the voltage of the DC power supply Vc rises too much, the discharge current of the capacitor C does not become lower than the holding current IH of the bidirectional switching element s shown in FIG. It is not possible to obtain oscillation and it is not possible to drive the light emitting diode 20 times. Moreover, the bidirectional switching element s has a very large difference △I between the pregover current IBo and the holding current IH, as shown in the characteristic diagram of Fig. □. DC power supply Vc
The voltage range in which oscillation is possible is extremely narrow, and if it fluctuates beyond a certain value, oscillation will stop. Even if the voltage of the DC power supply Vc is within the oscillation possible range, if the power supply voltage fluctuates, the oscillation period will be as shown by the virtual line in Fig. 6 by T=R9・Ctn() 30VC-VBO As a result, the light emitting diode cannot be driven normally.
この発明は、上記の欠点を解消するためになされたもの
で、発光ダイオードの駆動回路として、五 定電流回路
を介してコンデンサを直流源に接続し、このコンデンサ
と並列に所定の充電電位で導通するスイッチング素子と
発光ダイオードと抵抗器とを直列接続した構成とするこ
とにより、直流電源の電圧が変動しても、正常なし張発
振が得られ、しかも、その発振周期が一定である発光ダ
イオードの駆動回路を提供するものである。以下、この
発明の実施例を図面にもとずいて説明する。This invention was made in order to eliminate the above-mentioned drawbacks, and as a driving circuit for a light emitting diode, a capacitor is connected to a DC source via a constant current circuit, and conduction is conducted in parallel with the capacitor at a predetermined charging potential. By using a configuration in which a switching element, a light emitting diode, and a resistor are connected in series, normal tension oscillation can be obtained even when the voltage of the DC power supply fluctuates, and the oscillation period is constant. It provides a drive circuit. Embodiments of the present invention will be described below with reference to the drawings.
第１図はこの発明に係る発光ダイオードの駆動回路の１
ｆ１を示すもので、定電流回路ＣＩを介してコンデンサ
Ｃを直流電源Ｖｃに接続し、このコンデンサＣと並列に
所定の充電電位で導通するスイツチング素子Ｓと発光ダ
イオードＤと抗抗器Ｒ１とを直列接続して構成する。FIG. 1 shows one of the light emitting diode drive circuits according to the present invention.
f1, a capacitor C is connected to a DC power source Vc via a constant current circuit CI, and a switching element S, a light emitting diode D, and a resistor R1 are connected in parallel with the capacitor C and conductive at a predetermined charging potential. Configure by connecting in series.
上記定電流回路ＣＩとしては、第１図に示すように、ト
ランジスタＴＲのエミツタ・ベース間に抵抗器Ｒ２と定
電圧ダイオードＺＤを、コレクタ・ベース間に抵抗器Ｒ
３と抵抗器Ｒ４をそれぞれ介装して構成したものを用い
る。As shown in FIG. 1, the constant current circuit CI includes a resistor R2 and a constant voltage diode ZD between the emitter and base of the transistor TR, and a resistor R between the collector and base of the transistor TR.
3 and a resistor R4 are used.
この定電流回路ＣＩは、トランジスタのコレクタ電流が
エミツタ・ベース間の電圧によつて決まることを利用し
たもので、たとえば直流電源Ｖ。の電圧が上昇してトラ
ンジスタＴＲのベース電位があがり、コレクタ電流が増
大しようとしても、定電圧ダイオードＺＤによつてエミ
ツタ・ベース間の電圧は一定に保たれ、コレクタ電流も
＝定となる。この定電流回路によれば、抵抗器Ｒ２・Ｒ
３，Ｒ４の抵抗値を任意に選択することにより、直流源
Ｖｃの大きな電圧変動に対して電流が一定となるように
設計ができる。This constant current circuit CI utilizes the fact that the collector current of a transistor is determined by the voltage between the emitter and the base, for example, the DC power supply V. Even if the voltage rises and the base potential of transistor TR rises, and the collector current attempts to increase, the voltage between the emitter and base is kept constant by the constant voltage diode ZD, and the collector current also becomes constant. According to this constant current circuit, resistors R2 and R
3. By arbitrarily selecting the resistance value of R4, it is possible to design the current to be constant even with large voltage fluctuations of the DC source Vc.
丁なわち、定電流回路ＣＩは第２図に示すような特性を
有しており、電源電圧Ｖｃの電圧が変動しても、最小動
作電圧ＶＫと最大動作電圧ＶＰの間では一定となる。That is, the constant current circuit CI has a characteristic as shown in FIG. 2, and even if the power supply voltage Vc fluctuates, it remains constant between the minimum operating voltage VK and the maximum operating voltage VP.
そして、このコレクタ電流値ＩＰは電流制限抵抗Ｒ４，
Ｒ２によつ“（制御することができ、また、抵抗器Ｒ３
は定電圧ダイオードＺＤの保護を達成することができる
。このように、トランジスタＴＲと、このトランジスタ
ＴＲのエミツタ・コレクタ電流を制御する抵抗器Ｒ２，
Ｒ４と、上記トランジスタＴＲのベース電位を―定に保
持する定電圧ダイオードＺＤとからなる定電流回路ＣＩ
を介してコンデンサＣを直流電源ＶＣｖｃ接続すること
により、発光ダイオードの駆動回路を構成したから、回
路定数の変更が容易であり、電圧付様や電流仕様を容易
に変更できるから、ＤＣ２ＯＯＶなどの高電圧まで発振
可能となり、電源電圧ＶＣの範囲が広くとれて、単一の
定電流ダイオードを使用する場合より実用的である。This collector current value IP is determined by the current limiting resistor R4,
R2 (can be controlled by resistor R3)
can achieve the protection of the constant voltage diode ZD. In this way, the transistor TR and the resistor R2, which controls the emitter-collector current of this transistor TR,
A constant current circuit CI consisting of R4 and a constant voltage diode ZD that holds the base potential of the transistor TR constant.
Since the light emitting diode drive circuit is configured by connecting the capacitor C to the DC power supply VCvc through the It is possible to oscillate up to voltage, and the range of power supply voltage VC can be widened, making it more practical than using a single constant current diode.
第３図は上記発光ダイオードとしてスイツチング素子と
一体の負性抵抗発光ダイオードＮＤを用いたものである
。In FIG. 3, a negative resistance light emitting diode ND integrated with a switching element is used as the light emitting diode.
これによると、負性抵抗発光ダイオードＮＤ自体にスイ
ツチング機能があるのでスイツチング素子が不要となり
、部品点数の減少が図れる。第４図は、上記スイツチン
グ素子として、シリコン制御整流器ＳＣＲを用いたもの
で、その作動は、コンデンサＣの充電電圧が上昇し、こ
れがシリコン制御整流器ＳＣＲのゲートに印加されてシ
リコン制御整流器ＳＣＲは導通し、発光ダイオードＤお
よび抵抗器Ｒ６を通じて放電されて保持電流以下になる
と遮断するものである。According to this, since the negative resistance light emitting diode ND itself has a switching function, a switching element is not required, and the number of parts can be reduced. Fig. 4 shows a switch using a silicon-controlled rectifier SCR as the switching element, and its operation is such that the charging voltage of the capacitor C rises and this is applied to the gate of the silicon-controlled rectifier SCR, making the silicon-controlled rectifier SCR conductive. However, when the current is discharged through the light-emitting diode D and the resistor R6 and becomes less than the holding current, the current is cut off.
以上詳述したように、この発明に係る発光ダイオードの
駆動回路は、定電流回路を介してコンデンサを直流電源
に接続し、このコンデンサと並列に所定の充電電位で導
通するスイツチング素子と発光ダイオードと抵抗器とを
直列接続して構成したので、電源電圧の変動があつても
コンデンサの充電電流は一定となり、し張発振が得られ
、しかもその発振周期も一定で、発光ダイオードを正常
に駆動させることができる。As described in detail above, the light emitting diode drive circuit according to the present invention connects a capacitor to a DC power supply via a constant current circuit, and connects a switching element and a light emitting diode that are electrically connected at a predetermined charging potential in parallel with the capacitor. Since the capacitor is connected in series with a resistor, the charging current of the capacitor remains constant even when the power supply voltage fluctuates, resulting in tensile oscillation. Moreover, the oscillation period is also constant, allowing the light emitting diode to be driven normally. be able to.
第１図はこの発明に係る発光ダイオードの駆動回路図、
第２図は定電流ダイオードの特性図、第３図および第４
図は別の実施例を示す発光ダイオードの駆動回路図、第
５図は従来の発光ダイオードの駆動回路図、第６図はし
張発振を示す波形図、第７図は双方向性スイツチング素
子の特性図である。
ＣＩ・・・定電流回路、Ｃ・・・コンデンサ、Ｓ・・・
スイツチング素子、Ｄ・・・発光ダイオード、Ｒ１・・
・抵抗器、ＮＤ・・・負性抵抗発光ダイオード。FIG. 1 is a driving circuit diagram of a light emitting diode according to the present invention,
Figure 2 is a characteristic diagram of a constant current diode, Figures 3 and 4
Figure 5 is a driving circuit diagram of a light emitting diode showing another embodiment, Figure 5 is a driving circuit diagram of a conventional light emitting diode, Figure 6 is a waveform diagram showing oscillation in the oscillation mode, and Figure 7 is a diagram of a bidirectional switching element. It is a characteristic diagram. CI...constant current circuit, C...capacitor, S...
Switching element, D... light emitting diode, R1...
・Resistor, ND...Negative resistance light emitting diode.
Claims (1)
ッチング素子と発光ダイオードと抵抗器とを直列接続す
るとともに、トランジスタと、このトランジスタのエミ
ッタ・コレクタ電流を制御する抵抗器と、上記トランジ
スタのベース電位を一定に保持する定電圧ダイオードと
からなる定電流回路を介して上記コンデンサを直流電源
に接続した発光ダイオードの駆動回路。1 A switching element that conducts at a predetermined charging potential, a light emitting diode, and a resistor are connected in series in parallel with the capacitor, and a transistor, a resistor that controls the emitter-collector current of this transistor, and a base potential of the transistor are connected in series. A light emitting diode drive circuit in which the above capacitor is connected to a DC power source via a constant current circuit consisting of a constant voltage diode and a constant voltage diode.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP52135347A JPS5915392B2 (en) | 1977-11-10 | 1977-11-10 | Light emitting diode drive circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP52135347A JPS5915392B2 (en) | 1977-11-10 | 1977-11-10 | Light emitting diode drive circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5468184A JPS5468184A (en) | 1979-06-01 |
| JPS5915392B2 true JPS5915392B2 (en) | 1984-04-09 |
Family
ID=15149638
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP52135347A Expired JPS5915392B2 (en) | 1977-11-10 | 1977-11-10 | Light emitting diode drive circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5915392B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007150003A (en) * | 2005-11-29 | 2007-06-14 | Fuji Electric Device Technology Co Ltd | Insulated signal transmission circuit |
| AR054478A1 (en) * | 2006-06-15 | 2007-06-27 | Andres Gabriel Moresco | POWER SUPPLY CIRCUIT PROVISION OF AT LEAST ONE ELECTRONIC AND / OR ELECTRICAL COMPONENT |
-
1977
- 1977-11-10 JP JP52135347A patent/JPS5915392B2/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5468184A (en) | 1979-06-01 |
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