JPS61201483A - Driving circuit for light-emitting diode - Google Patents

Driving circuit for light-emitting diode

Info

Publication number
JPS61201483A
JPS61201483A JP60042174A JP4217485A JPS61201483A JP S61201483 A JPS61201483 A JP S61201483A JP 60042174 A JP60042174 A JP 60042174A JP 4217485 A JP4217485 A JP 4217485A JP S61201483 A JPS61201483 A JP S61201483A
Authority
JP
Japan
Prior art keywords
emitting diode
voltage
light
constant
diode
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
Application number
JP60042174A
Other languages
Japanese (ja)
Inventor
Masayuki Kuroba
黒羽　正之
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
NEC Corp
Original Assignee
NEC Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by NEC Corp filed Critical NEC Corp
Priority to JP60042174A priority Critical patent/JPS61201483A/en
Publication of JPS61201483A publication Critical patent/JPS61201483A/en
Pending legal-status Critical Current

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)
  • Control Of Indicators Other Than Cathode Ray Tubes (AREA)
  • Control Of El Displays (AREA)

Abstract

PURPOSE:To improve the recognition properties of lighting and non-lighting by making a constant current circuit, in which output currents from a constant- voltage generating circuit driven at supply voltage are determined, and a light- emitting diode driven by output currents from the constant current circuit to be contained. CONSTITUTION:VF=VCC-VCE holds in the forward voltage VF of a light- emitting diode 7. When a forward voltage threshold where the light-emitting diode 7 is lit is represented by VFT at that time, the diode 7 is lit when VFT<=VF =VCC-VCE holds, and the diode 7 is not lit at all when VF=VCC-VCE<VFT holds. Consequently, when the constant voltage value VZ of a constant voltage diode 5 is set previously at a value slightly lower than the forward voltage threshold VFT, the light-emitting diode 7 is not lit at all when supply voltage extends over a constant voltage value V2 or lower, and the diode 7 is lit at sufficient luminance when supply voltage is larger than the constant voltage value V2. Accordingly, the recognition properties of the lighting and non-lighting of the light-emitting diode 7 are improved.

Description

【発明の詳細な説明】 （産業上の利用分野） 本発明は、発光ダイオード駆動回路に関するものである
。DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a light emitting diode drive circuit.

（従来の技術） 従来発光ダイオードの駆動回路は、第２図に示す工うに
、電源２１に保護抵抗２２と発光ダイオード２３とを直
列に接続して構成しｔものや、第３図に示す工うな電源
３１に抵抗３６とツェナーダイオード３７とを直列に接
続し、ツェナー電圧を演算増幅器３２に加え、その出力
をトランジスタ３３に卑見、トランジスタ３３のエミッ
タに接続され比抵抗３５で演算増幅器３２に負帰還をか
けるとともに、トランジスタ３３のコレクタ出力で発光
ダイオード３４を駆動する定電流駆動方式のもの等があ
つ九。(Prior Art) Conventional light-emitting diode drive circuits have been constructed by connecting a protective resistor 22 and a light-emitting diode 23 in series to a power supply 21, as shown in FIG. 2, or as shown in FIG. A resistor 36 and a Zener diode 37 are connected in series to a power supply 31, a Zener voltage is applied to an operational amplifier 32, the output is connected to a transistor 33, and a resistor 35 is connected to the emitter of the transistor 33 to provide a negative voltage to the operational amplifier 32. There are also constant current drive systems that apply feedback and drive the light emitting diode 34 with the collector output of the transistor 33.

〔発明が解決しょうとする問題点〕[Problem that the invention seeks to solve]

前者の簡単な駆動回路でに、電源２１の変動にエフ発光
ダイオード２３０点灯状態に大きな変化が生じ九すする
。また、直列抵抗２２の値に工９不点灯状態が生じ九〇
、直列抵抗の値又は電源電圧値にＬっては十分な輝度エ
フ小さな輝度で点灯子る九め点灯、不点灯の認識が困難
になるといつｔ欠点があった。また後者の定電流駆動回
路では、電源３１からの電圧が一定であれば定電流動作
はするが、演算増幅器３２の電流変動検出に使用する抵
抗３６の両端電圧は、電源電圧に依存する几め、電源電
圧に変動があった場合には、定を流動作をしなくなった
り、あるいに、演算増幅器３２の動作電圧が比較的高く
なるため、低電圧回路でに使用できないとｈりた欠点が
あった。With the former simple drive circuit, fluctuations in the power supply 21 cause large changes in the lighting state of the F-light emitting diode 230. In addition, if the value of the series resistor 22 causes a non-lighting state, the value of the series resistor or the power supply voltage may be insufficient to ensure sufficient brightness. When it gets difficult there are no drawbacks. In addition, in the latter constant current drive circuit, if the voltage from the power supply 31 is constant, constant current operation is performed, but the voltage across the resistor 36 used to detect current fluctuations of the operational amplifier 32 is determined by a method that depends on the power supply voltage. If there is a fluctuation in the power supply voltage, the operational amplifier 32 may no longer operate at a constant current, or the operating voltage of the operational amplifier 32 may become relatively high, so it cannot be used in low voltage circuits. was there.

本発明の目的に、上記の欠点である発光ダイオードの点
灯・不点灯認識性が高く、電源変動があった場合の点灯
状態の変動のない発光ダイオード駆動回路を提供するこ
とにある。SUMMARY OF THE INVENTION An object of the present invention is to provide a light emitting diode drive circuit that has high ability to recognize whether a light emitting diode is turned on or off, which is the drawback described above, and which does not cause fluctuations in the lighting state even when there is a fluctuation in the power supply.

（問題点を解決するための手段） 本発明に工れば、電源電圧で駆動する定電圧発生回路と
、この定電圧発生回路の出力で出力電流が決められる定
電流回路と、定を流口路の出力電流で駆動される発光ダ
イオードとを含む発光ダイオード駆動回路を得る。(Means for Solving the Problems) The present invention provides a constant voltage generation circuit driven by a power supply voltage, a constant current circuit whose output current is determined by the output of this constant voltage generation circuit, and a constant current circuit. A light emitting diode driving circuit including a light emitting diode driven by an output current of a circuit is obtained.

（実施例） 以下、第１図を参照して、本発明をエリ詳細に説明する
。(Example) The present invention will be described in detail below with reference to FIG.

第１図は、本発明の一実施例である発光ダイオード駆動
回路である０発光ダイオード駆動回路は電源１．抵抗２
．抵抗３．ダイオード４．定電圧ダイオード５．トラン
ジスタ６、発光ダイオード７にエリ構成されている。発
光ダイオード７の順発電圧ｖＦに、 Ｖ、”　ＶＯＯ＋　ＶＯＲ となる。ここで、発光ダイオード７が点灯する順’ｌｃ
圧ｔ、’！！イ１［ｔ−Ｖ、Ｔトｆル、！：、ｖＦＴ≦
ｖＦ＝ｖｏｏ−ｖａｍ　　であれば点灯することになる
。また、ｖＦ”■００　ＶＯＩＩ　＜　ＶＦＴ　　であ
れば全く点灯しないことになる。したがって、定電圧ダ
イオード５の定電圧値ｖｚｔ順電圧しきｈ値”ＦＴより
わずかに低く設定しておくと、発光ダイオード７は電源
電圧が定電圧値ｖ２以下ならば完全に不点灯となＯ１電
源電圧が定電圧［Ｖ　ｚエリ大きければ十分な輝度で点
灯することとなる。この之め、尭光ダイオード７０点灯
・不点灯の認識性が高くなる。FIG. 1 shows a light emitting diode drive circuit according to an embodiment of the present invention. resistance 2
．． Resistance 3. Diode 4. Constant voltage diode 5. It is composed of a transistor 6 and a light emitting diode 7. The order voltage vF of the light emitting diode 7 is V, "VOO+VOR. Here, the order in which the light emitting diode 7 lights up is 'lc.
Pressure t,'! ! I1 [t-V, T-fl,! :, vFT≦
If vF=voo-vam, it will turn on. Also, if vF"■00 VOII < VFT, it will not light up at all. Therefore, if the constant voltage value vzt of the constant voltage diode 5 is set slightly lower than the forward voltage threshold h value "FT, the light emitting diode 7 If the power supply voltage is less than the constant voltage value v2, the light will not be lit completely, and if the power supply voltage O1 is greater than the constant voltage [Vz], the light will be lit with sufficient brightness. As a result, it is easier to recognize whether the photodiode 70 is lit or not.

ここで、７３以上の電圧が印加された状態では、抵抗２
．抵抗３．ダイオード４．定電圧ダイオード５．トラン
ジスタ６にエリ構成される定電流回路が動作し、電源変
動があっても変動は、定電圧ダイオード５でクランプさ
れ、定電流回路のバイアス電流は変動せず定電流動作を
維持し続ける。Here, when a voltage of 73 or more is applied, the resistance 2
．． Resistance 3. Diode 4. Constant voltage diode 5. A constant current circuit constituted by the transistor 6 operates, and even if there is a power supply fluctuation, the fluctuation is clamped by the constant voltage diode 5, and the bias current of the constant current circuit does not fluctuate and continues to maintain constant current operation.

このときの動作電圧は、ｖｃｃ　”　ＶＦ”ＶＯＩであ
り１通常発光ダイオードの頴電圧は１．６−２．ＯＶな
ので、■ｏＨの電圧値が低りもの、たとえば１ｖ程度の
ものを便用すればＶｏｏ＝ＺＳ〜３ｖ程度の低い電源電
圧で動作することになる。The operating voltage at this time is vcc"VF"VOI, and the voltage of one normal light emitting diode is 1.6-2. Since it is OV, if a device with a low voltage value of oH, for example about 1 V, is used, it will operate with a low power supply voltage of about Voo=ZS to 3 V.

（発明の効果） このように、本発明によれば、点灯・不点灯の認識性が
高く、一定し九点灯状態が得られ、かつ、低電圧動作を
させることができる発光ダイオード駆動回路が構成でき
るのは明白である。(Effects of the Invention) As described above, according to the present invention, a light emitting diode drive circuit is constructed that has high recognition of lighting/non-lighting, provides constant lighting states, and is capable of low voltage operation. It is obvious that it can be done.

【図面の簡単な説明】[Brief explanation of the drawing]

１１図は本発明の一実施例金子す発光ダイオード駆動回
路の回路図である。第２図および、！３図に、従来技術
による発光ダイオード駆動回路の回路図である。 ２１．３１・・・・・・電源、２．３，２２，３５，３
６・・・・・・抵抗、４・・・・・・ダイオード、５，
２３，３４・・・・・・定電圧ダイオード、６．３３・
・・・・・トランジスタ、７．２３．３４・・・・・・
発光ダ、イオード、３２・・・・・・演算増幅器。 井　／　回 ２２看Ｕ九 席　２　回 多　３　面FIG. 11 is a circuit diagram of a Kaneko light emitting diode driving circuit according to an embodiment of the present invention. Figure 2 and! FIG. 3 is a circuit diagram of a light emitting diode drive circuit according to the prior art. 21.31... Power supply, 2.3, 22, 35, 3
6...Resistance, 4...Diode, 5,
23, 34... Constant voltage diode, 6.33.
...Transistor, 7.23.34...
Light emitting diode, diodes, 32... operational amplifiers. I / 22 views U 9 seats 2 times 3 sides

Claims (1)

【特許請求の範囲】[Claims] 電源と、該電源で駆動されて定電圧を発生する定電圧発
生回路と、該定電圧発生回路の出力で定電流出力が決め
られる定電流発生回路と、該定電流発生回路の出力で駆
動される発光ダイオードとを有することを特徴とする発
光ダイオード駆動回路。A power source, a constant voltage generating circuit that is driven by the power source to generate a constant voltage, a constant current generating circuit whose constant current output is determined by the output of the constant voltage generating circuit, and a constant current generating circuit that is driven by the output of the constant current generating circuit. A light emitting diode drive circuit comprising: a light emitting diode;
JP60042174A 1985-03-04 1985-03-04 Driving circuit for light-emitting diode Pending JPS61201483A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP60042174A JPS61201483A (en) 1985-03-04 1985-03-04 Driving circuit for light-emitting diode

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP60042174A JPS61201483A (en) 1985-03-04 1985-03-04 Driving circuit for light-emitting diode

Publications (1)

Publication Number Publication Date
JPS61201483A true JPS61201483A (en) 1986-09-06

Family

ID=12628609

Family Applications (1)

Application Number Title Priority Date Filing Date
JP60042174A Pending JPS61201483A (en) 1985-03-04 1985-03-04 Driving circuit for light-emitting diode

Country Status (1)

Country Link
JP (1) JPS61201483A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5115147A (en) * 1988-06-01 1992-05-19 Canon Kabushiki Kaisha Driver for light emitting device for providing a stable beam output

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5115147A (en) * 1988-06-01 1992-05-19 Canon Kabushiki Kaisha Driver for light emitting device for providing a stable beam output

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