JPS6125336A - Drive circuit of light emitting element - Google Patents
Drive circuit of light emitting elementInfo
- Publication number
- JPS6125336A JPS6125336A JP14657484A JP14657484A JPS6125336A JP S6125336 A JPS6125336 A JP S6125336A JP 14657484 A JP14657484 A JP 14657484A JP 14657484 A JP14657484 A JP 14657484A JP S6125336 A JPS6125336 A JP S6125336A
- Authority
- JP
- Japan
- Prior art keywords
- emitting element
- light emitting
- light
- time constant
- 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
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/50—Transmitters
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/06—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium
- H01S5/068—Stabilisation of laser output parameters
- H01S5/06825—Protecting the laser, e.g. during switch-on/off, detection of malfunctioning or degradation
Landscapes
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Optical Communication System (AREA)
Abstract
Description
【発明の詳細な説明】
（イ）産業上の利用分野
この発明は、発光素子の駆動回路、特にサージ電流によ
る素子の永久破壊防止に工夫をこらしたた発光素子の駆
動回路に関する。DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a driving circuit for a light emitting element, and particularly to a driving circuit for a light emitting element that is devised to prevent permanent destruction of the element due to surge current.
（ロ）従来の技術
一般に、発光素子等の半導体素子を駆動する際に、サー
ジ電流による素子の永久破壊が起こり易い。それゆえ、
サージ電流を抑制して素子を保護する必要がある。この
サージ電流を抑制する従来発光素子の駆動回路として第
２図に示すものがある。(b) Prior Art Generally, when driving a semiconductor device such as a light emitting device, permanent destruction of the device is likely to occur due to surge current. therefore,
It is necessary to protect the device by suppressing surge current. A conventional drive circuit for a light emitting element that suppresses this surge current is shown in FIG.
この駆動回路において、電圧Ｖｃｃが印加されると、発
光素子ＬＤが駆動され、その出力光の一部が受光素子Ｐ
Ｄに照射される。そして、受光素子ＰＤの出力が一定と
なるように、したがって発光素子ＬＤの出力が一定とな
るように、オペアンプＡが作動制御する。すなわち、発
光素子Ｌ Ｄの出力が小さいと、大なる駆動電流がトラ
ンジスタＴｒを通して流れるように、オペアンプＡが制
御するし、逆に発光素子ＬＤの出力が大きいと、減少方
向に駆動電流がトランジスタＴγ１を通して流れるよう
に、オペアンプＡが制御する。In this drive circuit, when the voltage Vcc is applied, the light emitting element LD is driven and a part of its output light is transmitted to the light receiving element P.
D is irradiated. The operational amplifier A then controls the operation so that the output of the light receiving element PD is constant, and therefore the output of the light emitting element LD is constant. That is, when the output of the light emitting element LD is small, the operational amplifier A controls so that a large drive current flows through the transistor Tr, and conversely, when the output of the light emitting element LD is large, the drive current decreases through the transistor Tγ1. Operational amplifier A controls the current to flow through.
しかし、受光素子ＰＤの応答速度は、オペアンプＡ、ト
ランジスタＴπ１、発光素子ＬＤ等に比べて遅いので、
Ｒ１、Ｃ１の遅延回路がないと、次の問題が生じる。However, the response speed of the light receiving element PD is slower than that of the operational amplifier A, the transistor Tπ1, the light emitting element LD, etc.
Without the delay circuits R1 and C1, the following problem occurs.
すなわち、オペアンプＡの電源に、立上がりの速い電圧
を加えると、発光素子ＬＤが発光しても、発光素子は応
答し得ず、出力が導出されない。そのため、オペアンプ
Ａは、あたかも発光素子ＬＤの出力が小であるかのよう
に制御動作をなし、発光素子ＬＤに過大電流を流し、発
光素子ＬＤを破壊させてしまうことがある。この問題を
解決するために、Ｃ１、Ｒ１の遅延回路を電源Ｖｃｃと
、オペアンプＡの電源端間に設け、オペアンプＡ系の電
源の立上がりを受光素子ＰＤの応答速度より、数百倍以
上遅くし、過大電流による発光素子ＬＤの破壊を防止し
ている。That is, if a voltage that rises quickly is applied to the power supply of the operational amplifier A, even if the light emitting element LD emits light, the light emitting element cannot respond and no output is derived. Therefore, the operational amplifier A performs a control operation as if the output of the light emitting element LD is small, causing an excessive current to flow through the light emitting element LD, which may destroy the light emitting element LD. In order to solve this problem, a delay circuit of C1 and R1 is installed between the power supply Vcc and the power supply terminal of operational amplifier A, so that the power rise of the operational amplifier A system is several hundred times slower than the response speed of the photodetector PD. This prevents the light emitting element LD from being destroyed due to excessive current.
（ハ）発明が解決しようとする問題点
一般に、サージ電流は、電源のオン／オフ時にＡＣライ
ンから入るものと、駆動回路周辺の瞬間的なノイズによ
り、オペアンプ、信号ラインに直接入るものがある。上
記従来回路では、駆動回路周辺のノイズにより、オペア
ンプＡや信号ライン上に直接侵入するサージ電流に対し
ては弱いという問題があった。(c) Problems to be solved by the invention In general, surge currents can enter from the AC line when the power is turned on or off, or directly into the operational amplifier or signal line due to instantaneous noise around the drive circuit. . The conventional circuit described above has a problem in that it is vulnerable to surge currents that directly enter the operational amplifier A and the signal line due to noise around the drive circuit.
この発明は、電源のオン／オフ時にＡＣライン等から入
るサージ電流のみならず駆動回路周辺の瞬間的なノイズ
により、オペアンプ、信号ライン上に直接入るサージ電
流に対しても発光素子の破壊を防止し得る耐環境性の優
れた発光素子の駆動回路を提供することを目的としてい
る。This invention prevents the destruction of light emitting elements not only from surge currents that enter from AC lines when the power is turned on and off, but also from surge currents that enter directly into operational amplifiers and signal lines due to instantaneous noise around the drive circuit. The object of the present invention is to provide a driving circuit for a light emitting element with excellent environmental resistance.
（ニ）問題点を解決するための手段及び作用この発明の
発光素子の駆動回路は、上記問題点を解決するために、
フィードバンク回路系に、発光素子の駆動電流の時定数
を、受光素子の応答時定数以上とするローパスフィルタ
回路を設けるようにしている。(d) Means and operation for solving the problems In order to solve the above problems, the light emitting element drive circuit of the present invention has the following features:
The feed bank circuit system is provided with a low-pass filter circuit that makes the time constant of the drive current of the light emitting element equal to or greater than the response time constant of the light receiving element.
この発明の発光素子の駆動回路では、電源のオン／オフ
による変化分や回路周辺より直接サージ電流が侵入して
も、ローパスフィルタで受光素子の応答速度以上遅延さ
れて、発光素子側にフィードバックされる。In the light emitting element drive circuit of the present invention, even if a surge current enters directly from the vicinity of the circuit or changes due to power on/off, the low-pass filter delays the response speed of the light receiving element or more and feeds it back to the light emitting element. Ru.
（ホ）実施例
第１図は、この発明の１実施例を示す発光素子の駆動回
路の接続図である。この実施例回路は発光素子ＬＤと受
光素子ＰＤがパッケージ１内に収納された内蔵型の発光
素子が使用されている。受光素子ＰＤのアノードと接地
間には光出力検出用（モニタ用）の抵抗Ｒ１２が接続さ
れ、この抵抗Ｒ１２と受光素子の接続点すは、オペアン
プへの一入力端に接続されている。(e) Embodiment FIG. 1 is a connection diagram of a driving circuit for a light emitting element showing an embodiment of the present invention. This embodiment circuit uses a built-in light emitting element in which a light emitting element LD and a light receiving element PD are housed in a package 1. A resistor R12 for optical output detection (monitoring) is connected between the anode of the light receiving element PD and ground, and a connection point between this resistor R12 and the light receiving element is connected to one input terminal to an operational amplifier.
またツェナー素子ｚｄの両端の定電圧はボリュウムＶＲ
ＩＩによって調整され、基準電圧としてオペアンプＡの
十入力端に加えられるようになっている。すなわち、ボ
リュウムＶＲＩＩは、発光素子の光出力調整用の抵抗と
して設けられている。Also, the constant voltage across the Zener element zd is the volume VR
II and applied to the input terminal of operational amplifier A as a reference voltage. That is, the volume VRII is provided as a resistor for adjusting the light output of the light emitting element.
オペアンプＡは、受光素子ＰＤのｂ点よりのモニタ電圧
とボリュウムＶＲＩＩよりの基準電圧を一致させるため
に出力電圧を導出し、定電流用のトランジスタＴｒｌｌ
を駆動して、発光素子ＬＤに駆動電流を流すようになっ
ている。すなわち、オペアンプＡは受光素子ＰＤの出力
を一定にするために発光素子ＬＤの光出力を一定にする
ようにコントロールしている。これらオペアンプＡ１
トランジスタＴｒｌ１等でフィードバンク回路系を構成
している。The operational amplifier A derives an output voltage in order to match the monitor voltage from point b of the light receiving element PD with the reference voltage from the volume VRII, and outputs a constant current transistor Trll.
is driven to cause a drive current to flow through the light emitting element LD. That is, the operational amplifier A controls the light output of the light emitting element LD to be constant in order to keep the output of the light receiving element PD constant. These operational amplifiers A1
The transistor Trl1 and the like constitute a feed bank circuit system.
なお、電源Ｖｃｃ（ＩＯＶ）はオペアンプＡ等に印加さ
れ、オペアンプへの出力端と定電流用のトランジスタＴ
ｒｌｌのベース間に抵抗Ｒ１１、電解コンデンサＣ１ｌ
からなるローパスフィルタ２を設けている。このローパ
スフィルタ２を設けることにより、発光素子ＬＤの駆動
電流の立上がりの時定数を受光素子ＰＤの応答時定数（
応答速度）より遅くなるようにしている。いま、受光素
子ＰＤとして太陽電池を使用するものとすると太陽電池
の場合応答速度は１０−５秒程度であり、従ってローパ
スフィルタ２で１０−５秒以上の時定数を設定するよう
にしているや
この実施例回路において電源ＶｃｃがオペアンプＡに加
えられると、発光素子ＬＤに発光電流が流れ、発光素子
ＬＤの光を受けて受光素子ＰＤに出力電流が流れ、この
出力電流による検出電圧と基準電圧が一致するようにオ
ペアンプＡが動作制御するが、発光素子ＬＤの増大分は
、ローパスフィルタ２で１０−５秒以上遅延されてフィ
ードバンクされるので、発光素子ＬＤへの過大電流が流
れるのを防止し、発光素子ＬＤを保護することができる
。Note that the power supply Vcc (IOV) is applied to the operational amplifier A, etc., and the output terminal to the operational amplifier and the constant current transistor T
A resistor R11 and an electrolytic capacitor C1l are connected between the base of rll.
A low-pass filter 2 is provided. By providing this low-pass filter 2, the time constant of the rise of the drive current of the light emitting element LD can be changed to the response time constant of the light receiving element PD (
response speed). Now, if a solar cell is used as the light receiving element PD, the response speed of the solar cell is about 10-5 seconds, so the time constant of the low-pass filter 2 is set to 10-5 seconds or more. In this example circuit, when the power supply Vcc is applied to the operational amplifier A, a light emitting current flows through the light emitting element LD, an output current flows through the light receiving element PD upon receiving the light from the light emitting element LD, and a detection voltage and a reference voltage due to this output current are generated. The operational amplifier A controls the operation so that the values match, but the increase in the light emitting element LD is delayed by the low-pass filter 2 for more than 10-5 seconds and is fed-banked, so that excessive current flowing to the light emitting element LD is prevented. can be prevented and the light emitting element LD can be protected.
第３図に、抵抗Ｒ１１＝ＩＫΩ、電解コンデンサＣ１１
＝１００μＦを使用した場合の電源オン時の発光素子の
アノード電圧と受光素子のアノード電圧の変化実験デー
タを示している。同図においてａは発光素子のアノード
（ａ点）の変化域形であり、ｂは受光素子ＰＤのアノー
ド（ｂ点）の波形すなわち電圧立上がり特性を示してい
る。ａ点の時定数は、ζ＝１００ｍｓであった。In Figure 3, resistance R11 = IKΩ, electrolytic capacitor C11
2 shows experimental data on changes in the anode voltage of the light-emitting element and the anode voltage of the light-receiving element when the power is turned on when using 100 μF. In the figure, a shows the variation range shape of the anode (point a) of the light emitting element, and b shows the waveform, that is, the voltage rise characteristic, of the anode (point b) of the light receiving element PD. The time constant at point a was ζ=100 ms.
この図より受光素子ＰＤは充分に発光素子ＬＤの光出力
に応答できていることがわかる。From this figure, it can be seen that the light receiving element PD can sufficiently respond to the light output of the light emitting element LD.
なお、フィードバンク系の信号ライン上の時定数ζは、
発光素子ＬＤの光出力コントロールに悪影響がないこと
は実験的に確認されている。すなわち、フィードバンク
系の反応速度に対して充分な値である。Note that the time constant ζ on the signal line of the feedbank system is
It has been experimentally confirmed that there is no adverse effect on the light output control of the light emitting element LD. That is, this value is sufficient for the reaction rate of the feed bank system.
なお、上記実施例において、ローパスフィルタの電解コ
ンデンサＣ１ｌは、定電流トランジスタＴｒｌｌのベー
スと接地間に接続しているが、これに代えてトランジス
タＴｒｌｌのエミッタあるいはコレクタ側に接続しても
よい。In the above embodiment, the electrolytic capacitor C1l of the low-pass filter is connected between the base of the constant current transistor Trll and the ground, but it may be connected to the emitter or collector side of the transistor Trll instead.
（へ）発明の効果
この発明によれば、フィートバンク系にローパスフィル
タを設けて発光素子の駆動電流の時定数を受光素子の応
答時定数以上にするようにしているので電源電圧のオン
／オフ時のサージ電流はもちろんオペアンプＡ、信号ラ
イン近傍のサージ電流に対してもこれを抑制することが
でき、従って発光素子の保護を完全になすことができ、
耐環境性にすぐれた発光素子の駆動回路を得ることがで
きる。(F) Effects of the Invention According to this invention, a low-pass filter is provided in the foot bank system to make the time constant of the driving current of the light emitting element greater than the response time constant of the light receiving element, so that the power supply voltage can be turned on/off. It is possible to suppress not only the surge current at the time of operation but also the surge current near the operational amplifier A and the signal line, and therefore the light emitting element can be completely protected.
A driving circuit for a light emitting element with excellent environmental resistance can be obtained.
また、第２図に示した従来の回路に比し、トランジスタ
１１１１（Ｔｒ２）を省略できるので回路をより簡単、
安価に構成することができる。Also, compared to the conventional circuit shown in FIG. 2, the transistor 1111 (Tr2) can be omitted, making the circuit simpler and simpler.
It can be constructed at low cost.
第１図はこの発明の１実施例を示す発光素子の駆動回路
の接続図、第２図は、従来の発光素子の駆動回路を示す
接続図、第３図は上記実施例の駆動回路のローパスフィ
ルタの時定数をある値に選定した場合の発光素子のアノ
ードと受光素子のアノードの立上がり特性を示す一例図
である。
ＬＤ二発光素子、 ＰＤ：受光素子、Ａ：アンプ、
２：ローパスフィルタ、Ｔｒｌｌ：定電流トラ
ンジスタFig. 1 is a connection diagram of a drive circuit for a light emitting element showing one embodiment of the present invention, Fig. 2 is a connection diagram showing a conventional drive circuit for a light emitting element, and Fig. 3 is a low-pass connection diagram of the drive circuit of the above embodiment. FIG. 7 is an example diagram showing the rise characteristics of the anode of the light emitting element and the anode of the light receiving element when the time constant of the filter is selected to a certain value. LD dual light emitting element, PD: light receiving element, A: amplifier,
2: Low-pass filter, Trll: Constant current transistor
Claims (1)
ク回路系を介して、発光素子の駆動回路系にフィードバ
ックして、発光素子を定電流駆動する発光素子の駆動回
路において、 前記フィードバック回路系内に、発光素子の駆動電流の
時定数を受光素子の応答時定数以上とするローパスフィ
ルタ回路を設けたことを特徴とする発光素子の駆動回路
。(1) In a light emitting element drive circuit that feeds back the light output of the light emitting element to the light emitting element drive circuit system through a feedback circuit system including a light receiving element to drive the light emitting element with a constant current, the feedback circuit system includes: A driving circuit for a light-emitting element, characterized in that a low-pass filter circuit is provided for making the time constant of the driving current of the light-emitting element equal to or greater than the response time constant of the light-receiving element.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14657484A JPS6125336A (en) | 1984-07-13 | 1984-07-13 | Drive circuit of light emitting element |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14657484A JPS6125336A (en) | 1984-07-13 | 1984-07-13 | Drive circuit of light emitting element |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS6125336A true JPS6125336A (en) | 1986-02-04 |
Family
ID=15410767
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP14657484A Pending JPS6125336A (en) | 1984-07-13 | 1984-07-13 | Drive circuit of light emitting element |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6125336A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9167658B2 (en) | 2012-07-12 | 2015-10-20 | Panasonic Intellectual Property Management Co., Ltd. | Light emitting element lighting device and lighting fixture using same |
-
1984
- 1984-07-13 JP JP14657484A patent/JPS6125336A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9167658B2 (en) | 2012-07-12 | 2015-10-20 | Panasonic Intellectual Property Management Co., Ltd. | Light emitting element lighting device and lighting fixture using same |
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