JPS5919382A - Heat response compensating system for light emitting diode - Google Patents

Heat response compensating system for light emitting diode

Info

Publication number
JPS5919382A
JPS5919382A JP57129897A JP12989782A JPS5919382A JP S5919382 A JPS5919382 A JP S5919382A JP 57129897 A JP57129897 A JP 57129897A JP 12989782 A JP12989782 A JP 12989782A JP S5919382 A JPS5919382 A JP S5919382A
Authority
JP
Japan
Prior art keywords
light emitting
emitting diode
led
junction temperature
detected
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
JP57129897A
Other languages
Japanese (ja)
Inventor
Susumu Hanaoka
花岡　進
Koichi Oota
幸一 太田
Akihiko Ichikawa
明彦 市川
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.)
Fujitsu Ltd
Original Assignee
Fujitsu Ltd
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 Fujitsu Ltd filed Critical Fujitsu Ltd
Priority to JP57129897A priority Critical patent/JPS5919382A/en
Publication of JPS5919382A publication Critical patent/JPS5919382A/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)

Abstract

PURPOSE:To prevent the deterioration due to variation in the temperature by varying the diode drive current by the junction temperature detected by the forward voltage of a light emitting diode. CONSTITUTION:A light emitting diode (LED) 4 is driven by a gain variable amplifier 1, and LED drive circuits 2, 3, and jigs junction temperature is detected by a junction temperature detector 5. The detector 5 has a resistor Ri, connected in series with the LED 4, a resistor R, a diode D, and an operational amplifier 6, and the junction temperature is detected by the forward voltage of the LED 4. The detected temperature signal is fed through a voltage control operational amplifier 7 to a gain variable amplifier 1, thereby controlling the drive current of the LED 4. Thus, the nonlinearity between the light emitting power and current of the LED 4 can be improved and the deterioration of the characteristics can be prevented.

Description

【発明の詳細な説明】 （ａ）　　発明の技術分野 本発明は発光ダイオード（ＬＥＤ）を用いた直接光強度
変調方式において、特性劣化となる電流変化による発光
ダイオードのジャンクション温度変化に起因する電流〜
発光パワー間の非直線性の改善方法に関するものである
。Detailed Description of the Invention (a) Technical Field of the Invention The present invention relates to a direct light intensity modulation method using light emitting diodes (LEDs), in which currents caused by changes in the junction temperature of the light emitting diodes due to current changes that degrade characteristics.
The present invention relates to a method for improving nonlinearity between emission powers.

６）従来技術と問題点 従来技術における上記ジャンクション温度変化による電
流〜発光パワー間の非直線性の改善方法としては、エン
ファシス、ティエンファシス回路による変化量の圧縮、
又は一般的改善法であるフィード・フォーワード法、プ
リ争ディストーション法等が用いられ、■ＴＶ等の目的
には充分実用的な光アナログ・リンクが提供されている
。6) Prior art and problems In the conventional technology, methods for improving the non-linearity between the current and the light emitting power due to the above-mentioned junction temperature change include compression of the amount of change using emphasis and tie-emphasis circuits;
Alternatively, general improvement methods such as the feed-forward method and the pre-distortion method are used, and an optical analog link that is sufficiently practical for purposes such as TV is provided.

しかし更に高品質な放送用等は、波型特性に厳しい特性
を必要とし、従来技術では、ジャンクション温度変化に
よる波形劣化が無視し得ないと太う欠点がある。However, higher quality broadcasting applications require stricter waveform characteristics, and the prior art has the disadvantage that waveform deterioration due to junction temperature changes cannot be ignored.

（ｅ）　　発明の目的 本発明の目的は上記の欠点を除去［７、発光ダイオード
の熱的麦作による発光パワーの変化を補償する良好な方
法を提供することである。(e) Object of the invention The object of the present invention is to eliminate the above-mentioned drawbacks [7] and to provide a good method for compensating for changes in the luminous power of light-emitting diodes due to thermal cropping.

（ｄ）　　発明の構成 に記の目的は本発明によれば、発光ダイオードのジャン
クシ日ン温度を該発光ダイオードの順方向電圧によや検
出する検出部と、前記検出部出力により骸発光ダイオー
ドの駆動電流を変化させる利得可変部とより構成される
ととを特徴とする発光ダイオードの熱応答補償方式を提
供することによって達成される。(d) According to the present invention, the object described in the configuration of the invention is to include a detection section that detects the solar temperature of a light emitting diode according to the forward voltage of the light emitting diode, and a detection section that detects the temperature of the light emitting diode according to the forward voltage of the light emitting diode. This is achieved by providing a thermal response compensation method for a light emitting diode, which is characterized by comprising a gain variable section that changes a drive current.

（ｅ）　　発明の実施例 以下本発明の実施例を図面によって詳述する。(e) Examples of the invention Embodiments of the present invention will be described in detail below with reference to the drawings.

図は本発明の一構成例を示すもので、図中１は利得可変
増幅器、２，３はＬＥＤ駆動回路、４は発光ダイオード
、５はジャンクション温度検出回路で、演算増幅器６を
内臓する。７は電圧増幅用演算増幅器を示す。更にＲ１
は発光ダイオード４の内部抵抗と同じ値を持つ外部抵抗
、Ｄは発光ダイオードと相似の電圧〜電流特性を持つ整
流器、ＲはＤの内部抵抗と同じ値を持つ抵抗である。The figure shows a configuration example of the present invention. In the figure, 1 is a variable gain amplifier, 2 and 3 are LED drive circuits, 4 is a light emitting diode, and 5 is a junction temperature detection circuit, which includes an operational amplifier 6. 7 indicates an operational amplifier for voltage amplification. Furthermore, R1
is an external resistance having the same value as the internal resistance of the light emitting diode 4, D is a rectifier having voltage-current characteristics similar to that of the light emitting diode, and R is a resistor having the same value as the internal resistance of D.

一般にＬＥＤにおいて、発光パワーはジャンクション温
度に反比例するので、本発明はジャンクション温度を検
出１〜、これを用いて発光パワーの変化を補償しようと
するものである。即ち発光ダイオードのジャンクシロン
温度の検出を発光ダイオードの順方向電圧の変化で検出
しくジャンクション温度と順方向電圧は比例する）、電
流変化に伴う熱以外の電圧変化分を発光ダイオードと相
似で、熱変化を起さないダイオードと抵抗とからなる回
路により相殺して、温度による順方向電圧変化分のみを
取シ出して、順方向電圧変化分にょシＬＥＤ駆動電流を
加減して、発光パワーの変化分を補償するものである。Generally, in an LED, the light emitting power is inversely proportional to the junction temperature, so the present invention detects the junction temperature and uses this to compensate for changes in the light emitting power. In other words, the junction temperature of the light emitting diode is detected by the change in the forward voltage of the light emitting diode (junction temperature and forward voltage are proportional). This is offset by a circuit consisting of a diode and a resistor that does not cause any change, and only the forward voltage change due to temperature is extracted, and the LED drive current is adjusted by the forward voltage change to change the light emitting power. This will compensate for the amount.

ＬＥＤの順方向電圧をＶＦ、その温度変化分をΔｖＦと
し、ＬＥＤを流れる電流をＩ、　　Ｄを流れる電流をｌ
とすれば、 ｖｌ−Ｒ１・■十ＶＦ＋ΔＶ　Ｆ　　　　　　　　　　
　　　（１）Ｖ２＝Ｒ・１＋ＶＦ　　　　　　　　　　
　　　　　　　（２）Ａ点の電圧をＶ。とすれば、 ｖｏ　　＝Ｖ、　　十Ｒ１−Ｉ ＝２Ｒ１・■十ＶＦ十ΔＶＦ　　　　　　　　　　　　
（３）一方 Ｖ、　−Ｖ　Ｆ＝　２　Ｒ・１ 、　　　１ ・°弓−１百（Ｖｏ−ＶＦ） （２）よシ Ｖ、＝Ｒ・２Ｒ−（ＶｏＶＦ）十Ｖ１ｒ−２（Ｖｏ　　
　ＶＦ）　十Ｖｐ （３）をイ吏うと １ Ｖｔ　　　２　　（２Ｒｉ・Ｉ　＋ＶＦ十ΔＶＦ−ｖＦ
）　＋ｖ１＝　（４）ｖ２−Ｒ１・■十（ＴΔＶｐ・＋
ＶＦ）　　　　　　　　（５）＝３− ＶｌとＶ、との差をＶｓとすれば、 ｖ、＝−土ΔｖＦ ２（６） となり、ｖ３はジャンクシロン温度変化による電圧変化
量を表わす。ＬＥＤの発光パワーの変化分をΔＰとすれ
ば、 ΔＰはΔＴに反比例し、 ジャンクシロン温度の変化分をΔＴとすれば、ΔＴはΔ
ｖＦに比例する。The forward voltage of the LED is VF, its temperature change is ΔvF, the current flowing through the LED is I, and the current flowing through D is l.
Then, vl-R1・■10VF+ΔVF
(1) V2=R・1+VF
(2) The voltage at point A is V. Then, vo = V, 10R1-I = 2R1・■10VF1ΔVF
(3) On the other hand, V, -V F= 2 R・1, 1 ・°bow −100 (Vo−VF) (2) Yoshi V, = R・2R− (VoVF) 10V1r−2 (Vo
VF) 1 Vp (3) is 1 Vt 2 (2Ri・I +VF1ΔVF−vF
) +v1= (4)v2-R1・■ten(TΔVp・+
VF) (5) = 3- If the difference between Vl and V is Vs, then v, = - ΔvF 2 (6) where v3 represents the amount of voltage change due to temperature change. If the change in LED light emitting power is ΔP, then ΔP is inversely proportional to ΔT. If the change in Junxillon temperature is ΔT, ΔT is ΔT.
Proportional to vF.

このようにして、発光ダイオードの熱的変化による発光
パワーの変化を補償することが出来る。In this way, changes in light emitting power due to thermal changes in the light emitting diode can be compensated for.

一般にΔＶＦ／ΔＴ−２〜４ｍＶ／℃ ΔＰ／ΔＴ＝０．０５係／℃ の値かえられる。従って信号電流自身の変化に伴い変化
するジャンクション温度変化による発光パワーの変化分
を補償することが出来る。Generally, the value can be changed by ΔVF/ΔT-2 to 4 mV/°C ΔP/ΔT=0.05 factor/°C. Therefore, it is possible to compensate for a change in light emission power due to a change in junction temperature that changes with a change in the signal current itself.

（ｆ）　　発明の効果 以上詳細に説明したように、本発明にょシ発光ダイオー
ドの発光パワールミ流量の非直線性を改善すると云う大
きい効果がある。(f) Effects of the Invention As explained in detail above, the present invention has the great effect of improving the nonlinearity of the luminous power flow rate of the light emitting diode.

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

＝４− =4-

Claims (1)

【特許請求の範囲】[Claims] 発光ダイオードのジャンクション温度を該発光ダイオー
ドの順方向電圧によシ検出する検出部と、前記検出部出
力により該発光ダイオードの駆動電流を変化させる利得
可変部とよ多構成されることを特徴とする発光ダイオー
ドの熱応答補償方式０It is characterized by being comprised of a detection section that detects the junction temperature of the light emitting diode based on the forward voltage of the light emitting diode, and a gain variable section that changes the driving current of the light emitting diode based on the output of the detection section. Light emitting diode thermal response compensation method 0
JP57129897A 1982-07-26 1982-07-26 Heat response compensating system for light emitting diode Pending JPS5919382A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP57129897A JPS5919382A (en) 1982-07-26 1982-07-26 Heat response compensating system for light emitting diode

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP57129897A JPS5919382A (en) 1982-07-26 1982-07-26 Heat response compensating system for light emitting diode

Publications (1)

Publication Number Publication Date
JPS5919382A true JPS5919382A (en) 1984-01-31

Family

ID=15021068

Family Applications (1)

Application Number Title Priority Date Filing Date
JP57129897A Pending JPS5919382A (en) 1982-07-26 1982-07-26 Heat response compensating system for light emitting diode

Country Status (1)

Country Link
JP (1) JPS5919382A (en)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH07226536A (en) * 1994-02-14 1995-08-22 Stanley Electric Co Ltd Led color information display board
JP2007095391A (en) * 2005-09-27 2007-04-12 Hitachi Lighting Ltd Led light source device
JP2008004827A (en) * 2006-06-23 2008-01-10 Matsushita Electric Ind Co Ltd Light source system
JP2008004828A (en) * 2006-06-23 2008-01-10 Matsushita Electric Ind Co Ltd Light source, and light source system employing it
US7553028B2 (en) 2004-05-11 2009-06-30 Infocus Corporation Projection LED cooling
WO2009095854A3 (en) * 2008-01-28 2009-12-10 Nxp B.V. Led driver circuit and method, and system and method for estimating the junction temperature of a light emitting diode
WO2020049331A1 (en) * 2018-09-05 2020-03-12 Olympus Corporation Led driver circuit

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH07226536A (en) * 1994-02-14 1995-08-22 Stanley Electric Co Ltd Led color information display board
US7553028B2 (en) 2004-05-11 2009-06-30 Infocus Corporation Projection LED cooling
JP2007095391A (en) * 2005-09-27 2007-04-12 Hitachi Lighting Ltd Led light source device
JP4722649B2 (en) * 2005-09-27 2011-07-13 日立アプライアンス株式会社 LED light source device
JP2008004827A (en) * 2006-06-23 2008-01-10 Matsushita Electric Ind Co Ltd Light source system
JP2008004828A (en) * 2006-06-23 2008-01-10 Matsushita Electric Ind Co Ltd Light source, and light source system employing it
WO2009095854A3 (en) * 2008-01-28 2009-12-10 Nxp B.V. Led driver circuit and method, and system and method for estimating the junction temperature of a light emitting diode
US8278831B2 (en) 2008-01-28 2012-10-02 Nxp B.V. LED driver circuit and method, and system and method for estimating the junction temperature of a light emitting diode
WO2020049331A1 (en) * 2018-09-05 2020-03-12 Olympus Corporation Led driver circuit

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