JPH073887B2 - Light emitting diode drive circuit - Google Patents
Light emitting diode drive circuitInfo
- Publication number
- JPH073887B2 JPH073887B2 JP14479685A JP14479685A JPH073887B2 JP H073887 B2 JPH073887 B2 JP H073887B2 JP 14479685 A JP14479685 A JP 14479685A JP 14479685 A JP14479685 A JP 14479685A JP H073887 B2 JPH073887 B2 JP H073887B2
- Authority
- JP
- Japan
- Prior art keywords
- light emitting
- emitting diode
- current
- drive circuit
- transistor
- 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 - Lifetime
Links
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
- H05B45/395—Linear regulators
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
- Y02B20/30—Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]
Landscapes
- Led Devices (AREA)
- Electronic Switches (AREA)
- Optical Communication System (AREA)
Description
【発明の詳細な説明】 〔発明の利用分野〕 本発明は、光通信用の発光ダイオード駆動回路に係り、
特に発光ダイオードの順電流を安定化するのに好適な駆
動回路に関する。Description: FIELD OF THE INVENTION The present invention relates to a light emitting diode drive circuit for optical communication,
In particular, the present invention relates to a drive circuit suitable for stabilizing the forward current of a light emitting diode.
従来から発光ダイオードの駆動回路としては、例えば実
用新案出願公報昭59-7790号に記載されているように、
トランジスタによる駆動が一般的である。Conventionally, as a drive circuit of a light emitting diode, as described in, for example, Utility Model Application Publication No. 59-7790,
Driving by a transistor is common.
しかし、このようにトランジスタによる駆動回路では発
光ダイオードの順電流の安定化については考えられてお
らず、特に電源電圧変動や発光ダイオードの順電圧の変
化によつて順電流が変化し、発光ダイオードの光出力が
変動して、安定した距離の光空間通信ができないという
問題があつた。However, in such a drive circuit using a transistor, stabilization of the forward current of the light emitting diode is not considered, and in particular, the forward current changes due to the fluctuation of the power supply voltage or the change of the forward voltage of the light emitting diode. There was a problem that the optical output fluctuated and optical space communication over a stable distance could not be performed.
本発明の目的は、発光ダイオードの駆動回路に定電流回
路を付加して、電源電圧変動や発光ダイオードの順電圧
の変化等による発光ダイオードの駆動電流の変動を少な
くし、安定した光出力を発する発光ダイオード駆動回路
を提供することにある。An object of the present invention is to add a constant current circuit to a drive circuit for a light emitting diode to reduce a change in the drive current of the light emitting diode due to a change in power supply voltage, a change in forward voltage of the light emitting diode, etc., and generate a stable light output. It is to provide a light emitting diode driving circuit.
本発明は前記目的を達成するために、発光ダイオードと
駆動回路との間、又は電源と発光ダイオードとの間に抵
抗及びトランジスタから成る定電流回路を接続し駆動電
流を安定化して、発光ダイオードの光出力を安定化せし
めるようにしたものである。In order to achieve the above object, the present invention connects a constant current circuit composed of a resistor and a transistor between a light emitting diode and a driving circuit or between a power source and a light emitting diode to stabilize the driving current, and It is designed to stabilize the light output.
以下、本発明の構成および一実施例を第１図第２図によ
り説明する。The structure and one embodiment of the present invention will be described below with reference to FIG. 1 and FIG.
第１図は本発明の回路構成を示すブロツク図で、１は直
流電流入力端子（陽極）,2は駆動信号入力端子,3は接地
端（陰極）,4は発光ダイオード,5は定電流回路,6はスイ
ツチング駆動回路を示す。本発明では、第１図に示すブ
ロツク構成により、スイツチング駆動回路６のオン・オ
フに伴う発光ダイオード４へ流れる駆動電流が、定電流
回路５によつて定電流化され、直流電源入力端子１の直
流入力電圧，発光ダイオード４の順電圧，スイツチング
駆動回路６のオン抵抗の変動の影響を受けずに、発光ダ
イオード４の光出力を安定化することができる。FIG. 1 is a block diagram showing a circuit configuration of the present invention. 1 is a direct current input terminal (anode), 2 is a drive signal input terminal, 3 is a ground terminal (cathode), 4 is a light emitting diode, and 5 is a constant current circuit. Reference numerals 6 designate a switching drive circuit. In the present invention, with the block configuration shown in FIG. 1, the drive current flowing to the light emitting diode 4 when the switching drive circuit 6 is turned on / off is converted into a constant current by the constant current circuit 5, and the DC power input terminal 1 The light output of the light emitting diode 4 can be stabilized without being affected by the fluctuations of the DC input voltage, the forward voltage of the light emitting diode 4, and the ON resistance of the switching drive circuit 6.
第１図に示すブロツク構成では、発光ダイオード４の挿
入位置を、定電流回路５とスイツチング駆動回路６の間
としたが、直流電源端子１と定電流回路５との間に挿入
しても同じ効果が得られる。In the block configuration shown in FIG. 1, the insertion position of the light emitting diode 4 is between the constant current circuit 5 and the switching drive circuit 6, but it is the same even if it is inserted between the DC power supply terminal 1 and the constant current circuit 5. The effect is obtained.
次に、第１図のブロツク構成に基づく本発明の具体的な
実施例の回路構成を第２図に示す。第２図において、５
は定電流回路を示し、トランジスタ10,11および抵抗7,8
から構成される。抵抗９は、定電流回路のオン電流の立
上り時間を短くするためのスピードアツプ用の抵抗で、
スイツチング速度が高速を必要とする場合に設けるもの
である。６はスイツチング駆動回路を示し、本発明の一
実施例では、トランジスタ12のみで構成したが、他のア
ナログスイツチや、ドライバーICに置替えることが可能
である。まず、駆動信号を駆動信号入力端子２に入力す
ると、スイツチング駆動回路６のトランジスタ12がオン
・オフ状態を繰返す。トランジスタ12がオンした場合、
トランジスタ10のエミツク電位が下がり、トランジスタ
10のベース電流が、直流電流端子1,抵抗7,トランジスタ
10,抵抗8,発光ダイオード4,トランジスタ12を介して接
地端３へ流れるルートで増加し、トランジスタ10のコレ
クタ電流はベース電流の増加に比例して、直流電流端子
1,トランジスタ10,抵抗8,発光ダイオード4,トランジス
タ12,接地端３のルートで流れ、発光ダイオード４を発
光させる。ここで、トランジスタ10のベース電流とコレ
クタ電流の比は、一般的にトランジスタの電流増幅率は
100以上であるから、ベース電流＜コレクタ電流と考え
られ、抵抗８を流れる電流は、トランジスタ10のコレク
タ電流にほぼ等しいとみなすことができる。一方、トラ
ンジスタ11は、トランジスタ10のベース電流を制御して
おり、抵抗８に流れるトランジスタ10のコレクタ電流が
増加し、それに伴い抵抗８に発生する電圧が増加してト
ランジスタ11のベース・エミツタ間電圧：VBEに達する
とトランジスタ11のコレクタ・エミツタ間の電流が増加
することにより、トランジスタ10のベース電流が減少す
る。このため抵抗８を流れる電流、すなわち発光ダイオ
ード４を流れる順電流は一定の電流値で制限がかかり、
定電流となる。いま、トランジスタ11のベース・エミツ
タ間の電圧をVBE，抵抗８の抵抗値をR0とすると、発光
ダイオード４の順電流IFは、 IF≒VBE／R0 と近似される。Next, FIG. 2 shows a circuit configuration of a concrete embodiment of the present invention based on the block configuration of FIG. In FIG. 2, 5
Indicates a constant current circuit, transistors 10 and 11 and resistors 7 and 8
Composed of. The resistor 9 is a resistor for speed-up to shorten the rise time of the on-current of the constant current circuit,
This is provided when a high switching speed is required. Reference numeral 6 denotes a switching drive circuit, which is composed of only the transistor 12 in the embodiment of the present invention, but can be replaced with another analog switch or a driver IC. First, when a drive signal is input to the drive signal input terminal 2, the transistor 12 of the switching drive circuit 6 repeats the on / off state. If transistor 12 turns on,
The emission potential of the transistor 10 drops and the transistor
Base current of 10 is DC current terminal 1, resistor 7, transistor
10, the resistor 8, the light emitting diode 4, the transistor 12 increases through the route that flows to the ground terminal 3, the collector current of the transistor 10 is proportional to the increase of the base current, the DC current terminal
1, the transistor 10, the resistor 8, the light emitting diode 4, the transistor 12, and the ground terminal 3 flow through the route to cause the light emitting diode 4 to emit light. Here, the ratio of the base current to the collector current of the transistor 10 is
Since it is 100 or more, it can be considered that the base current <collector current, and the current flowing through the resistor 8 can be regarded as substantially equal to the collector current of the transistor 10. On the other hand, the transistor 11 controls the base current of the transistor 10, the collector current of the transistor 10 flowing through the resistor 8 increases, and the voltage generated at the resistor 8 increases accordingly, and the base-emitter voltage of the transistor 11 increases. : When reaching V BE , the collector-emitter current of the transistor 11 increases, and the base current of the transistor 10 decreases. Therefore, the current flowing through the resistor 8, that is, the forward current flowing through the light emitting diode 4 is limited to a constant current value,
It becomes a constant current. Now, assuming that the voltage between the base and the emitter of the transistor 11 is V BE and the resistance value of the resistor 8 is R 0 , the forward current I F of the light emitting diode 4 is approximated as I F ≈V BE / R 0 .
上式より、発光ダイオードの順電流は、直流電源端子１
への入力電圧の変動，発光ダイオード４の順電圧の変
動，スイツチング駆動回路６のオン抵抗の影響を受け
ず、定電流となり、発光ダイオード４の光出力の安定を
図ることができる。From the above formula, the forward current of the light emitting diode is
It is possible to stabilize the light output of the light emitting diode 4 without being influenced by the fluctuation of the input voltage to the light emitting diode, the fluctuation of the forward voltage of the light emitting diode 4, and the on-resistance of the switching drive circuit 6, which results in a constant current.
第２図における抵抗９は、スイツチング駆動回路６のト
ランジスタ12がオフの場合、つまり発光ダイオードに電
流が流れていない間に、トランジスタ10のベース電流
を、直流電源端子1,抵抗7,トランジスタ10,抵抗8,抵抗
9,接地端のルートで微少に流し、トランジスタ10をオン
状態として、スイツチング駆動回路６がオンとなつた際
の発光ダイオード４への順電流の立上を速めるものであ
る。本発明の実施例では、トランジスタ10,11を立上り
時間が遅い安価なトランジスタを使用したため、スピー
ドアツプ用の抵抗９を挿入した例を示したが、トランジ
スタ10,11に高速のトランジスタを使用した場合、また
は発光ダイオード４へのスイツチング駆動周期に高速を
必要としない場合には、抵抗９を省くことも可能であ
る。The resistor 9 in FIG. 2 supplies the base current of the transistor 10 to the DC power supply terminal 1, the resistor 7, the transistor 10, when the transistor 12 of the switching drive circuit 6 is off, that is, while no current flows in the light emitting diode. Resistance 8, resistance
9. A small amount of current is passed through the route of the ground terminal to turn on the transistor 10 to accelerate the rise of forward current to the light emitting diode 4 when the switching drive circuit 6 is turned on. In the embodiment of the present invention, an inexpensive transistor having a slow rise time is used as the transistors 10 and 11, and therefore an example in which the resistor 9 for speed-up is inserted is shown. However, when a high-speed transistor is used as the transistors 10 and 11. Alternatively, the resistor 9 may be omitted if the switching drive cycle to the light emitting diode 4 does not require a high speed.
以上の説明のごとく、本発明の定電流回路５を発光ダイ
オード４の順電流ルート間に挿入することにより、発光
駆動電流の定電流化を図れ、光出力を安定化することが
できる。As described above, by inserting the constant current circuit 5 of the present invention between the forward current routes of the light emitting diode 4, the light emission drive current can be made constant and the light output can be stabilized.
本実施例では、発光ダイオード４の挿入位置を定電流回
路５とスイツチング駆動回路６との間としたが、直流電
下端子１と、定電流回路５との間に挿入することも可能
である。Although the light emitting diode 4 is inserted between the constant current circuit 5 and the switching drive circuit 6 in this embodiment, it may be inserted between the DC power-down terminal 1 and the constant current circuit 5.
本発明によれば、簡単かつ安価な回路構成にて発光ダイ
オードの駆動電流の変動を少なくし安定した光出力を発
する駆動回路が実現出来る。According to the present invention, it is possible to realize a drive circuit which emits a stable light output by reducing the fluctuation of the drive current of the light emitting diode with a simple and inexpensive circuit configuration.
特に複数の発光ダイオードを直列接続して成る光送信機
を形成する場合に、従来の方法では、発光ダイオードの
順電圧のバラツキが駆動電流の変動に及ぼす影響が大き
く、安定な光出力が得られないという不具合があつた
が、本発明の回路を採用することにより光出力の変動を
少なくすることができ、安定した距離の光通信が可能と
なる。Particularly in the case of forming an optical transmitter in which a plurality of light emitting diodes are connected in series, according to the conventional method, the fluctuation of the forward voltage of the light emitting diodes has a great influence on the fluctuation of the drive current, and a stable light output can be obtained. However, by adopting the circuit of the present invention, fluctuations in optical output can be reduced, and optical communication over a stable distance becomes possible.
第１図は本発明のブロツク図、第２図は本発明の一実施
例を示す回路構成図である。 １……直流電流端子、２……駆動信号入力端子、３……
接地端、４……発光ダイオード５……定電流回路、６…
…スイツチング駆動回路、7,8,9……抵抗、10,11,12…
…トランジスタFIG. 1 is a block diagram of the present invention, and FIG. 2 is a circuit configuration diagram showing an embodiment of the present invention. 1 ... DC current terminal, 2 ... Drive signal input terminal, 3 ...
Ground terminal, 4 ... Light emitting diode, 5 ... Constant current circuit, 6 ...
… Switching drive circuit, 7,8,9 …… Resistance, 10,11,12…
... transistor
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 昭54−144892（ＪＰ，Ａ) 特開 昭58−14584（ＪＰ，Ａ) 実開 昭58−182448（ＪＰ，Ｕ) 実開 昭59−93158（ＪＰ，Ｕ) ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-54-144892 (JP, A) JP-A-58-14584 (JP, A) Actually open Sho-58-182448 (JP, U) Actual-open Sho-59- 93158 (JP, U)
Claims (1)
イオードを駆動する駆動回路と、定電流回路とで構成さ
れ、定電流回路を電源と発光ダイオードとの間もしくは
発光ダイオードと駆動回路との間に接続した発光ダイオ
ード駆動回路において、定電流回路の出力と発光ダイオ
ードの接続点とアースとの間もしくは定電流回路の出力
と駆動回路の接続点とアースとの間に、抵抗もしくはダ
イオードもしくはトランジスタからなる素子群より選択
した素子を接続して、発光ダイオードが駆動されていな
い場合にも定電流回路に電流を流すことを特徴とする発
光ダイオード駆動回路。1. A light emitting diode, a drive circuit for driving the light emitting diode by an input signal, and a constant current circuit. The constant current circuit is provided between a power supply and the light emitting diode or between the light emitting diode and the drive circuit. In the connected light emitting diode drive circuit, consists of a resistor or a diode or a transistor between the output of the constant current circuit and the connection point of the light emitting diode and ground, or between the output of the constant current circuit and the connection point of the drive circuit and ground. A light emitting diode drive circuit characterized in that an element selected from an element group is connected to allow a current to flow through a constant current circuit even when the light emitting diode is not driven.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14479685A JPH073887B2 (en) | 1985-07-03 | 1985-07-03 | Light emitting diode drive circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14479685A JPH073887B2 (en) | 1985-07-03 | 1985-07-03 | Light emitting diode drive circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS627175A JPS627175A (en) | 1987-01-14 |
| JPH073887B2 true JPH073887B2 (en) | 1995-01-18 |
Family
ID=15370655
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP14479685A Expired - Lifetime JPH073887B2 (en) | 1985-07-03 | 1985-07-03 | Light emitting diode drive circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH073887B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| IT1292717B1 (en) * | 1997-04-24 | 1999-02-11 | Incerti & Simonini Di Incerti | LOW VOLTAGE LIGHTING DEVICE. |
| JP3654876B2 (en) * | 2002-07-15 | 2005-06-02 | 株式会社シマノ | Bicycle lighting device drive |
-
1985
- 1985-07-03 JP JP14479685A patent/JPH073887B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPS627175A (en) | 1987-01-14 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP3061923B2 (en) | Driver circuit for semiconductor light emitting device | |
| US6466080B2 (en) | Constant current driver circuit | |
| US5315606A (en) | Laser diode driving circuit | |
| KR910005362B1 (en) | Display drive device | |
| JPH073887B2 (en) | Light emitting diode drive circuit | |
| JP2537290B2 (en) | Driving circuit for semiconductor light emitting device | |
| JP3593623B2 (en) | Light emitting element drive circuit | |
| US5939907A (en) | Low power, high speed driving circuit for driving switching elements | |
| JP3488088B2 (en) | Light emitting diode drive circuit | |
| JP2773484B2 (en) | Laser diode drive circuit | |
| US4508979A (en) | Single-ended push-pull circuit having a small through-current | |
| US4727264A (en) | Fast, low-power, low-drop driver circuit | |
| JPH05129665A (en) | Led drive circuit | |
| JP2738969B2 (en) | Light emitting element drive circuit | |
| JP2815434B2 (en) | Output circuit device | |
| JPH02103984A (en) | Semiconductor-laser driving circuit | |
| KR920005091Y1 (en) | Circuit cutting low power | |
| JPS6179331A (en) | Drive control circuit of light emitting element | |
| SU589600A1 (en) | Pulsed-type voltage stabilizer | |
| KR100262337B1 (en) | Current control type gradation field emission display device driving circuit using switched resistor | |
| JP2000332298A (en) | Light emitting diode drive circuit | |
| KR920000333B1 (en) | Stabilization Circuit of Low Power Supply Shutdown Circuit Using Current Ratio | |
| KR930006376Y1 (en) | LED Drive Circuit | |
| KR960003378Y1 (en) | Chopper circuit | |
| JPH11340561A (en) | Laser diode drive circuit |