JPS63213379A - Led driving circuit - Google Patents
Led driving circuitInfo
- Publication number
- JPS63213379A JPS63213379A JP62044096A JP4409687A JPS63213379A JP S63213379 A JPS63213379 A JP S63213379A JP 62044096 A JP62044096 A JP 62044096A JP 4409687 A JP4409687 A JP 4409687A JP S63213379 A JPS63213379 A JP S63213379A
- Authority
- JP
- Japan
- Prior art keywords
- led
- whose
- constant voltage
- power supply
- light output
- 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.)
- Pending
Links
- 230000005540 biological transmission Effects 0.000 abstract description 7
- 230000002542 deteriorative effect Effects 0.000 abstract description 2
- 230000006866 deterioration Effects 0.000 abstract 1
- 230000003287 optical effect Effects 0.000 description 23
- 238000010586 diagram Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 2
- 230000003213 activating effect Effects 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
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)
- Optical Communication System (AREA)
Abstract
Description
【発明の詳細な説明】
産業上の利用分野
本発明はディジタル光通信方式におけるＬＥＤ駆動回路
に関し、特にＬＥＤの光出力を外部端子によシ制御して
、可変を可能にするＬＥＤ駆動回路に関するものである
。DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an LED drive circuit in a digital optical communication system, and more particularly to an LED drive circuit that controls the light output of an LED using an external terminal to make it variable. It is.
従来の技術
従来、この種のＬＥＤ駆動回路の一例は第２図に示すよ
うに、電源端子２と、この電源端子２に一端を接続する
抵抗器３と、この抵抗器３の他端にアノードを接続する
ＬＥＤ４と、このＬＥＤ４のカソードにコレクタを、信
号入力端子１をベースに接続し、エミッタを接地する駆
動用トランジスタ５とからなり、信号入力端子ｌに印加
されるディジタル信号入力によって駆動用トランジスタ
５をオン・オフして、ＬＥＤ４に電流を流すものであっ
た。BACKGROUND OF THE INVENTION Conventionally, an example of this type of LED driving circuit, as shown in FIG. It consists of a driving transistor 5 whose collector is connected to the cathode of the LED 4, whose base is connected to the signal input terminal 1, and whose emitter is grounded. The transistor 5 was turned on and off to cause current to flow through the LED 4.
したがってＬＥＤ４の光出力は、ＬＥＤに流れる電流に
よって決定され、この電流は電源電圧とＬＥＤ４の順方
向電圧と、抵抗器、３の抵抗値とによって決定されるも
のであった。Therefore, the light output of the LED 4 is determined by the current flowing through the LED, and this current is determined by the power supply voltage, the forward voltage of the LED 4, and the resistance value of the resistor 3.
一方ディジタル光通信の光受信回路は、ある程度の光入
力レベル範囲に対しては受信可能であるが、極端に光入
力レベルが大きい場合には、増幅器が飽和して受信不能
とな９、特に受信感度の高いＰＩＮ−ＦＥＴ方式の受信
回路では顕著になるという欠点があった。また、これに
対処するために、抵抗器３にタップなどを設け、これを
切替えてＬＥＤ４の光出力を変化させることも行われる
が、切替え端子までの電線の長さが長くなってしまい、
そのインダクタンスによってＬＥＤの光出力波形が劣化
してしまうという欠点があった。On the other hand, optical receiving circuits for digital optical communications can receive light within a certain range of optical input levels, but when the optical input level is extremely high, the amplifier becomes saturated and reception becomes impossible9. This problem becomes more noticeable in a highly sensitive PIN-FET type receiving circuit. In order to deal with this, it is also possible to provide a tap on the resistor 3 and switch it to change the light output of the LED 4, but this increases the length of the electric wire to the switching terminal.
There was a drawback that the optical output waveform of the LED deteriorated due to the inductance.
発明が解決しようとする問題点
本発明の目的は、上記の欠点、すなわち光受信回路の光
入力レベルが極端に大きいと、受信レベル範囲を超えて
受信不能になり、また、この対策としてＬＥＤの直列の
抵抗器の抵抗値を切替える場合には、ＬＥＤの光出力波
形が劣下してしまうという問題点を解決したＬＥＤ駆動
回路を提供することにある。Problems to be Solved by the Invention The purpose of the present invention is to solve the above-mentioned drawbacks, that is, if the optical input level of the optical receiving circuit is extremely high, it will exceed the reception level range and become impossible to receive. An object of the present invention is to provide an LED drive circuit that solves the problem that the optical output waveform of an LED deteriorates when switching the resistance value of a series resistor.
問題点を解決するための手段
本発明は上述の問題点を解決するために、電源端子と、
この電源端子にコレクタを共通に接続する複数の回路切
替用トランジスタと、これらのトランジスタの夫々のベ
ースに出力端子を接続し、入力端子を制御信号入力端子
とする同数の定電圧電源と、同じく夫々の回路切替用ト
ランジスタのエミッタに一端を接続する同数の抵抗器と
、これら抵抗器の他端を共通にしてアノードに接続され
るＬＥＤと、このＬＥＤのカソードをコレクタに、信号
入力端子をベースに接続し、エミッタを接地する駆動用
トランジスタとからなる構成を採用するものである。Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a power supply terminal;
A plurality of circuit switching transistors whose collectors are commonly connected to this power supply terminal, an equal number of constant voltage power supplies whose output terminals are connected to the bases of each of these transistors, and whose input terminals are used as control signal input terminals; The same number of resistors have one end connected to the emitter of the circuit switching transistor, an LED has the other end of these resistors connected to the anode, and the cathode of this LED is the collector, and the signal input terminal is the base. This configuration employs a configuration consisting of a drive transistor connected to the drive transistor and a drive transistor whose emitter is grounded.
作用
本発明は上述のように構成したので、複数の制御信号入
力端子の内の任意の１つに制御信号を送シ特定の定電圧
電源を作動させることによシ、この定電圧電源の出力端
子をベースに接続する回路切替用トランジスタがオンし
て、直列に接続する特定の抵抗器を介してＬＥＤが接続
−さ卓、駆動用゛トランジスタのベースの信号入力端子
からの信号入力によってＬＥＤが駆動される。従ってＬ
ＥＤの光出力は、制御信号によって切替られる回路の定
電圧電源の電圧、抵抗器の抵抗値によって主に決定され
る。Operation Since the present invention is configured as described above, by sending a control signal to any one of the plurality of control signal input terminals and activating a specific constant voltage power source, the output of this constant voltage power source can be changed. The circuit switching transistor that connects the terminal to the base is turned on, and the LED is connected through a specific resistor connected in series.The LED is switched on by the signal input from the signal input terminal of the base of the driving transistor. Driven. Therefore L
The optical output of the ED is mainly determined by the voltage of a constant voltage power supply of a circuit switched by a control signal and the resistance value of a resistor.
実施例 次に本発明の実施例について図面を参照して説明する。Example Next, embodiments of the present invention will be described with reference to the drawings.
本発明の一実施例を回路図で示す第１図を参照すると、
本発明のＬＥＤ駆動回路は、電源端子２と、この電源端
子２にコレクタを共通に接続する２個の回路切替用の第
２および第３のトランジスタ６および７と、第２のトラ
ンジスタ６０ベースに出力端子を接続し、第１の制御信
号入力端子１１を有する第１の定電圧電源９と、第３の
トランジスタ７０ベースに出力端子を接続し、第２の制
御信号入力端子１２を有する第２の定電圧電源１０と、
第２のトランジスタ６のエミッタに一端を接続する第１
の抵抗器３と、第３のトランジスタ７のエミッタに一端
を接続する第２の抵抗器８と、第１および第２の抵抗器
３および８の他端を共通にしてアノードを接続するＬＥ
Ｄ４と、このＬＥＤ４のカソードをコレクタに、信号入
力端子１をベースに接続し、エミッタを接地する駆動用
の第１のトランジスタ５とから々っている。Referring to FIG. 1, which shows a circuit diagram of an embodiment of the present invention,
The LED drive circuit of the present invention includes a power supply terminal 2, two second and third transistors 6 and 7 for circuit switching whose collectors are commonly connected to the power supply terminal 2, and a second transistor 60 connected to the base. a first constant voltage power supply 9 having an output terminal connected to it and having a first control signal input terminal 11; a second constant voltage power supply 9 having an output terminal connected to the base of the third transistor 70 and having a second control signal input terminal 12; a constant voltage power supply 10,
a first transistor whose one end is connected to the emitter of the second transistor 6;
a second resistor 8 whose one end is connected to the emitter of the third transistor 7; and an LE whose anodes are connected to each other with the other ends of the first and second resistors 3 and 8 in common.
D4 and a first transistor 5 for driving, which connects the cathode of this LED 4 to its collector, the signal input terminal 1 to its base, and has its emitter grounded.
次に本実施例の動作について第１図を用いて説明する。Next, the operation of this embodiment will be explained using FIG.
まず、第１の制御信号入力端子１１からの信号によって
第１の定電圧電源９がオンの場合、ＬＥＤ４に流れる電
流Ｉｌは第１の定電圧電源９の電圧ｖＣ１＋第２のトラ
ンジスタ６のベース−エミッタ間電圧ＶＢＫ２．ＬＥＤ
４の順方向電圧ＶＬＥＤおよび第１の抵抗器３の抵抗値
Ｒ１で決定され、この電流に対応してＬＥＤ４の光出力
が決定される。First, when the first constant voltage power supply 9 is turned on by a signal from the first control signal input terminal 11, the current Il flowing through the LED 4 is the voltage vC1 of the first constant voltage power supply 9+the base of the second transistor 6- Emitter voltage VBK2. LED
4 and the resistance value R1 of the first resistor 3, and the light output of the LED 4 is determined in accordance with this current.
同様に第２の定電圧電源１ｏがオンの場合、ＬＥＤ４に
流れる電流１２は第２の定電圧電源１ｏの電圧ＶＣ２，
第３のトランジスタ７のベース・エミｙｌ’間電圧ＶＢ
）ｉ！３．ＬＥＤ４の順方向電圧ＶＬＥＤおよび第２の
抵抗器８の抵抗値Ｒ２で決定される。Similarly, when the second constant voltage power supply 1o is on, the current 12 flowing through the LED 4 is the voltage VC2 of the second constant voltage power supply 1o,
Voltage VB between base and emitter yl' of third transistor 7
) i! 3. It is determined by the forward voltage VLED of the LED 4 and the resistance value R2 of the second resistor 8.
すなわちＬＥＤ４に流れる電流工１および■２は次式と
なる。That is, the electric currents 1 and 2 flowing through the LED 4 are expressed by the following equation.
またＬＥＤの光出力はＬＥＤ４に流れる電流に概ね比例
する。Further, the light output of the LED is approximately proportional to the current flowing through the LED 4.
従って抵抗値Ｒ１ｔ Ｒ２を適切に選べば、ＬＥＤ４の
光出力を所望の値に選ぶことができる。例えば通常の使
用状態のＬＥＤ４の光出力をＲ１で設定し、光受信回路
の光入力レベルが極端に大きい場合（光伝送路長が極端
に短い場合等）のＬＥＤ４の光出力をＲ２で設定するこ
とによって、全ての光伝送路長に対し光伝送が可能とな
る。Therefore, by appropriately selecting the resistance values R1t R2, the light output of the LED 4 can be selected to a desired value. For example, use R1 to set the optical output of LED4 in normal use, and use R2 to set the optical output of LED4 when the optical input level of the optical receiver circuit is extremely high (such as when the optical transmission path length is extremely short). This enables optical transmission for all optical transmission path lengths.
また、本発明ではＬＥＤ４の光出力波形を決定する高速
動作の回路部分以外のところで光出力の制御を行うため
、ＬＥＤ４の光出力波形の劣化は生じないという利点が
ある。Furthermore, the present invention has the advantage that the optical output waveform of the LED 4 does not deteriorate because the optical output is controlled in a part other than the high-speed operation circuit that determines the optical output waveform of the LED 4.
なお、本実施例では、定電圧電源、切替用トランジスタ
および直列抵抗器を２個ずつとしたが、３個以上を用い
ることによ）、より広いＬＥＤＯ元出力のレベルの切替
を行なうことができる。Note that in this embodiment, two constant voltage power supplies, two switching transistors, and two series resistors were used, but by using three or more, it is possible to switch the level of the LED source output over a wider range. .
発明の効果
以上に説明したように、本発明によれば、外部よジオン
・オフの制御可能な定電圧電源切替用トランジスタおよ
び抵抗器を複数個ずつ設けることにより、ＬＥＤ光出力
波形の劣化なしに光出力を可変でき、光伝送が可能な光
伝送路長の範囲を拡大できるという効果がある。Effects of the Invention As explained above, according to the present invention, by providing a plurality of constant-voltage power supply switching transistors and resistors that can be externally controlled to turn on and off, it is possible to prevent the LED light output waveform from deteriorating. This has the effect of being able to vary the optical output and expanding the range of optical transmission path lengths that can be used for optical transmission.
第１図は本発明のＬＥＤ駆動回路の実施例の回路図、第
２図は従来のＬＥＤ駆動回路の一例の回路図である。
１・・・信号入力端子、２・・・電源端子、３・・・第
１の抵抗器、４・・・ＬＥＤ、５・・・第１のトランジ
スタ（駆動用）、６・・・第２のトランジスタ（切替用
）、７・・・第３のトランジスタ（切替用）、８・・・
第２の抵抗器、９・・・第１の定電圧電源、 ：ｉ、６
・・・第２の定電圧電源、１１・・・第１の制御信号入
力端子、１２・・・第２の制御信号入力端子。
とヒ二Ｌニジ
茶 ＩＩ！Ｉ
竿 ２ 図FIG. 1 is a circuit diagram of an embodiment of the LED drive circuit of the present invention, and FIG. 2 is a circuit diagram of an example of a conventional LED drive circuit. DESCRIPTION OF SYMBOLS 1... Signal input terminal, 2... Power supply terminal, 3... First resistor, 4... LED, 5... First transistor (for driving), 6... Second transistor (for switching), 7... third transistor (for switching), 8...
Second resistor, 9...first constant voltage power supply, :i, 6
. . . second constant voltage power supply, 11 . . . first control signal input terminal, 12 . . . second control signal input terminal. And Hiji L Nijicha II! I rod 2 diagram
Claims (1)
、この抵抗器の他端にアノードを接続するＬＥＤと、こ
のＬＥＤのカソードをコレクタに、信号入力端子をベー
スに接続し、エミッタを接地する駆動用トランジスタと
からなるＬＥＤ駆動回路において、前記抵抗器に代えて
、制御信号によって出力電圧がオン・オフする複数の定
電圧電源と、これら複数の定電圧電源の出力をベースに
、前記電源端子をコレクタに接続する同数の回路切替用
トランジスタと、これらの回路切替用トランジスタのエ
ミッタの夫々に一端を接続し、他端を共通にして前記Ｌ
ＥＤのアノードに接続する同数の抵抗器とよりなる切替
回路を設けたことを特徴とするＬＥＤ駆動回路。A power supply terminal, a resistor with one end connected to this power supply terminal, an LED whose anode is connected to the other end of this resistor, the cathode of this LED is connected to the collector, the signal input terminal is connected to the base, and the emitter is connected to the In an LED drive circuit consisting of a grounded drive transistor, in place of the resistor, there are a plurality of constant voltage power supplies whose output voltages are turned on and off by control signals, and the above-mentioned The same number of circuit switching transistors whose power supply terminals are connected to their collectors are connected at one end to each of the emitters of these circuit switching transistors, and the other end is connected in common to the L.
An LED drive circuit characterized in that a switching circuit including the same number of resistors connected to an anode of an ED is provided.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62044096A JPS63213379A (en) | 1987-02-28 | 1987-02-28 | Led driving circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62044096A JPS63213379A (en) | 1987-02-28 | 1987-02-28 | Led driving circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS63213379A true JPS63213379A (en) | 1988-09-06 |
Family
ID=12682087
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62044096A Pending JPS63213379A (en) | 1987-02-28 | 1987-02-28 | Led driving circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS63213379A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0262854U (en) * | 1988-10-27 | 1990-05-10 |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6133458B2 (en) * | 1981-12-28 | 1986-08-02 | Koken Kk | |
| JPS63253973A (en) * | 1987-04-10 | 1988-10-20 | Nec Corp | Light emission diode driving system |
-
1987
- 1987-02-28 JP JP62044096A patent/JPS63213379A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6133458B2 (en) * | 1981-12-28 | 1986-08-02 | Koken Kk | |
| JPS63253973A (en) * | 1987-04-10 | 1988-10-20 | Nec Corp | Light emission diode driving system |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0262854U (en) * | 1988-10-27 | 1990-05-10 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US2576026A (en) | Electronic switch | |
| CA1229655A (en) | Led driver circuit | |
| JPH11214183A (en) | Light emitting circuit | |
| EP0224185A2 (en) | Laser diode driving circuit | |
| US4384219A (en) | Voltage comparator hysteresis control circuit | |
| JPH0329207B2 (en) | ||
| US4417240A (en) | Plural output switched current amplifier as for driving light emitting diodes | |
| US4462003A (en) | Variable gain amplifier | |
| US4295063A (en) | Fast settling digital to analog converter bit switch | |
| JPS63213379A (en) | Led driving circuit | |
| US6510168B1 (en) | Laser diode drive circuit | |
| EP0496449B1 (en) | Switching bridge amplifier | |
| US4461960A (en) | High speed switching circuit | |
| US5402013A (en) | Common mode logic multiplexer configuration | |
| JPH09306193A (en) | Sample-and-hold circuit | |
| US3978295A (en) | Circuit arrangement for a tone pushbutton selection telephone subscriber set | |
| JPH04227314A (en) | Digital delay circuit | |
| US4163159A (en) | Attenuation-free electronic switch | |
| KR100257637B1 (en) | Differential amplifier with limited output current | |
| US4800585A (en) | Saturating bipolar switch circuit for telephone dial pulsing | |
| JP2847149B2 (en) | Switching circuit | |
| US4122362A (en) | Stepped pulse generator circuit | |
| KR100262337B1 (en) | A current controlled fed driving circuit for gray scale processing using the switched resister | |
| SU1319269A1 (en) | Multichannel switching device | |
| JP2710487B2 (en) | Semiconductor light emitting element drive circuit |