JPH01214080A - Semiconductor laser driving circuit - Google Patents

Semiconductor laser driving circuit

Info

Publication number
JPH01214080A
JPH01214080A JP3882788A JP3882788A JPH01214080A JP H01214080 A JPH01214080 A JP H01214080A JP 3882788 A JP3882788 A JP 3882788A JP 3882788 A JP3882788 A JP 3882788A JP H01214080 A JPH01214080 A JP H01214080A
Authority
JP
Japan
Prior art keywords
circuit
reference voltage
reverse voltage
absolute value
comparator
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
JP3882788A
Other languages
Japanese (ja)
Inventor
Mitsuhiro Horikawa
堀川　満広
Michio Yanagisawa
通雄 柳澤
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.)
Seiko Epson Corp
Original Assignee
Seiko Epson 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 Seiko Epson Corp filed Critical Seiko Epson Corp
Priority to JP3882788A priority Critical patent/JPH01214080A/en
Publication of JPH01214080A publication Critical patent/JPH01214080A/en
Pending legal-status Critical Current

Links

Classifications

    • 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
    • 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
    • H01S5/06808—Stabilisation of laser output parameters by monitoring the electrical laser parameters, e.g. voltage or current

Landscapes

  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Optics & Photonics (AREA)
  • Semiconductor Lasers (AREA)

Abstract

PURPOSE:To obtain a highly reliable LD driving circuit which can be used regardless to utility conditions such as a modulation speed and has an LD protective circuit against static electricity and a surge from a circuit by a method wherein the protective circuit which makes the cathode and anode of the LD short-circuited when the absolute value of the reverse voltage of the LD exceeds the absolute value of a reference voltage is provided. CONSTITUTION:Circuits 4-8 which detect the reverse voltage of a semiconductor laser (LD) 3, a reference voltage generating circuit 12 which generates a reference voltage necessary for setting the maximum reverse voltage of the LD 3, a comparator 16 which compares the reverse voltage of the LD 3 with the reference voltage and changes its output level in accordance with the result of comparison and an LD protective circuit composed of a circuit 1 which makes the cathode and anode of the LD 3 short-circuited when a signal showing that the absolute value of the reverse voltage of the LD 3 is larger than the absolute value of the reference voltage is outputted by the comparator 16 are provided in a circuit driving the LD 3. Further, for instance, the emitted luminous power of the LD 3 is monitored by a PD 2 and fed back to an APC circuit 15 and the output of the APD circuit 15 is given to a constant-current circuit.

Description

【発明の詳細な説明】 ［産業上の利用分野］ 本発明は、半導体レーザ駆動回路に関する。[Detailed description of the invention] [Industrial application field] The present invention relates to a semiconductor laser drive circuit.

［従来の技術］ 従来のＬＤ駆動回路におけるＬＤ保護回路は、例えば第
２図に示すようにＬＤのすぐ近くにインダクタ（第２図
１７のし）とキャパシタ（第２図１８のＣ）を入れて、
静電気や回路からのサージに対してＬＤを保護するのが
一般的であった。[Prior Art] The LD protection circuit in a conventional LD drive circuit, for example, as shown in FIG. hand,
It was common to protect LDs from static electricity and surges from circuits.

［発明が解決しようとする課題］ しかし、前述の従来技術ではＬＤを高速変調する場合に
はＬＣの時定数をその変調周波数に応じて変更し、広範
囲の変調を可能にする必要があった。また第２図１９０
ＦＥＴ　（電界効果型トランジスタ）のドレイン負荷に
インダクタを用いると、駆動電流が過渡的に非常に大き
くなる可能性があるという問題点を有する。[Problems to be Solved by the Invention] However, in the above-mentioned conventional technology, when modulating the LD at high speed, it was necessary to change the time constant of the LC according to the modulation frequency to enable a wide range of modulation. Also, Fig. 2 190
When an inductor is used as a drain load of an FET (field effect transistor), there is a problem in that the drive current may become extremely large transiently.

そこで本発明はこのような問題点を解決するもので、そ
の目的とするところは変調速度等のＬＤの使用条件に関
わらず使用できる静電気や回路からのサージに対するＬ
Ｄの保護回路を有する高信頼性のＬＤ駆動回路を提供す
るところにある。Therefore, the present invention is intended to solve these problems, and its purpose is to provide a L
An object of the present invention is to provide a highly reliable LD drive circuit having a protection circuit of D.

［課題を解決するための手段］ 本発明の半導体レーザ駆動回路は、 ａ）ＬＤの逆方向電圧を検出する回路と、ｂ）ＬＤの最
大逆方向電圧を設定するために必要な基準電圧を発生す
る基準電圧発生回路回路と、Ｃ）該基準電圧とＬＤの逆
方向電圧を比較して、その大小によって出力レベルの変
化するコンパレータと、 ｄ）該コンパレータから前記基準電圧の絶対値よりＬＤ
の逆方向電圧の絶対値が大きいことを示す信号が出力さ
れた場合にはＬＤのカソードとアノード間を短絡する回
路からなるＬＤ保護回路を有することを特徴とする。お
よび前記コンパレータがヒステリシス特性を有すること
を特徴とする。[Means for Solving the Problems] The semiconductor laser drive circuit of the present invention includes a) a circuit for detecting the reverse voltage of the LD, and b) generating a reference voltage necessary for setting the maximum reverse voltage of the LD. C) a comparator that compares the reference voltage with the reverse voltage of the LD and changes the output level depending on the magnitude thereof; and d) a comparator that changes the output level of the LD from the absolute value of the reference voltage from the comparator.
The present invention is characterized in that it has an LD protection circuit including a circuit that short-circuits the cathode and anode of the LD when a signal indicating that the absolute value of the reverse voltage is large is output. and the comparator has hysteresis characteristics.

［実施例コ 以下、本発明を実施例に基づき図面を用いて詳細に説明
する。[Example] The present invention will be explained in detail based on an example using the drawings.

第１図は、本発明による実施例を示すＬＤ駆動回路であ
る。一般にＬＤ駆動回路には周囲の温度変化等によりＬ
Ｄの出射光量が変化することのないようにＡＰＣ（オー
トマチックパワーコントロール）の機能が要求されるが
、本実施例にもＡＰＣの機能を付加した。ＡＰＣ回路の
中身は本発明では特に規定しないのでその詳細について
は述べない。構成としては、第１図３のＬＤの出射光量
を第１図２のＰＤ（ホトダイオード）でモニタし、それ
を第１図１５のＡＰＣ回路にフィードバックする。そし
てＡＰＣ回路からの出力■を定電流回路へ出力する。Ｌ
Ｄの出射パワーＰは、第１図１３の抵抗値をＲＬ、第１
図１４の基準電圧を■。とじて、 Ｐ＝　　η　（■。−■）／ＲＬ となる。ただし、η［ワット／アンペアコはＬＤの微分
効率である。FIG. 1 shows an LD driving circuit showing an embodiment according to the present invention. In general, the LD drive circuit is affected by changes in ambient temperature, etc.
An APC (automatic power control) function is required so that the amount of light emitted from D does not change, and the APC function is added to this embodiment as well. Since the contents of the APC circuit are not particularly defined in the present invention, the details thereof will not be described. As for the configuration, the amount of light emitted from the LD shown in FIG. 1 is monitored by a PD (photodiode) shown in FIG. 1 and 2, and it is fed back to the APC circuit shown in FIG. 1. Then, the output (2) from the APC circuit is output to the constant current circuit. L
The output power P of D is the resistance value of FIG.
The reference voltage in Figure 14 is ■. Then, P= η (■.-■)/RL. However, η[watts/ampere co is the differential efficiency of the LD.

さて、本発明のＬＤ保護回路部分であるが、簡単に言う
とＬＤの逆方向電圧をモニタしてそれが所定の電圧より
大きくなったらＬＤのアノード、カソードを短絡するこ
とによってＬＤをオフにする構成になっている。Now, regarding the LD protection circuit part of the present invention, to put it simply, the reverse voltage of the LD is monitored, and when it becomes larger than a predetermined voltage, the LD is turned off by short-circuiting the anode and cathode of the LD. It is configured.

第１図８のオペアンプおよび４．５．６．７の各抵抗か
らなる差動増幅器でＬＤの逆方向電圧を検出する。ＬＤ
のアノード側（ＶＡ）を該差動増幅器のマイナス入力端
の抵抗５に、カソードＩ＋１（ＶＣ）を差動増幅器のプ
ラス入力端の抵抗４にそれぞれ接続する。差動増幅器の
出力ｖｏｕｖは、抵抗４．５．６および７の値をそれぞ
れＲ１、Ｒ１、Ｒ２、Ｒ２として、 ＶＯＵＴ＝Ｒ２（ＶＡ　　ＶＣ）　／Ｒ１と表される。The reverse voltage of the LD is detected by a differential amplifier consisting of the operational amplifier shown in FIG. 1 and resistors 4.5.6.7. L.D.
The anode side (VA) of the differential amplifier is connected to the resistor 5 at the negative input terminal of the differential amplifier, and the cathode I+1 (VC) is connected to the resistor 4 at the positive input terminal of the differential amplifier. The output vouv of the differential amplifier is expressed as VOUT=R2(VA VC)/R1, where the values of resistors 4, 5, 6 and 7 are R1, R1, R2, and R2, respectively.

このＶ、ＯＵＴと第１図１２の基準電圧発生回路の出力
■ＲＥＦを第１図１６のコンパレータを用いて比較する
。This V,OUT is compared with the output -REF of the reference voltage generating circuit shown in FIG. 12 using the comparator shown in FIG. 16.

このコンパレータはヒステリシスを持っており、具体的
には第１図９、ｌＯおよび１１の抵抗値をそれぞれＲ３
、Ｒ３、Ｒ４とした時、コンパレータの出力をＨまたは
Ｌと表して、 ＶＲＭＡＸ＝ＶＲＥＦ＋Ｒ３（ＨＶＲＥＦ）　／　（Ｒ
３＋ＲＶＲＭＩＮ：ＶＲＥＦ−Ｒ３（Ｌ−ＶＲＥＦ）　
／　（Ｒ３＋Ｒと表されるしきい値の上限、下限を有す
る。This comparator has hysteresis, and specifically, the resistance values of 9, 10 and 11 in FIG.
, R3, and R4, the output of the comparator is expressed as H or L, and VRMAX=VREF+R3(HVREF)/(R
3+RVRMIN:VREF-R3(L-VREF)
/ (has an upper and lower threshold value expressed as R3+R).

本実施例では、 ■０υτ＞　Ｖ　Ｒ旧Ｎ となったら、コンパレータの出力はＬとなり、第１図１
のアナログスイッチがオンとなり、ＬＤのアノードとカ
ソードが短絡する。In this example, if ■0υτ> V R old N, the output of the comparator becomes L, and as shown in FIG.
The analog switch is turned on, and the anode and cathode of the LD are shorted.

［発明の効果］ 以上述べたように本発明によればＬＤ駆動回路に、 ａ）ＬＤの逆方向電圧を検出する回路と、ｂ）該逆方向
電圧と比較して、ＬＤをオフにするか否か決定するため
に必要な基準電圧を発生するための回路と、 Ｃ）該基準電圧とＬＤの逆方向電圧を比較して、その大
小によって出力レベルの変化するコンパレータと、 ｄ）該コンパレータから前記基準電圧の絶対値よりＬＤ
の逆方向電圧の絶対値が大きいことを示す信号が出力さ
れた場合にはＬＤのカソードとアノード間を短絡する回
路からなるＬＤ保護回路を付加することにより、変調周
波数等のＬＤの使用条件に関わらず静電気や回路からの
サージに対するＬＤの保護機能を有する高信頼性のＬＤ
駆動回路を得ることができる。尚、本発明の応用例とし
ては光メモリ、レーザビームプリンタ等が考えられる。[Effects of the Invention] As described above, according to the present invention, the LD drive circuit includes a) a circuit that detects the reverse voltage of the LD, and b) a circuit that detects the reverse voltage of the LD and turns off the LD. C) a comparator that compares the reference voltage with the reverse voltage of the LD and changes its output level depending on the magnitude of the comparison; d) a circuit that generates a reference voltage necessary to determine whether the From the absolute value of the reference voltage, LD
By adding an LD protection circuit consisting of a circuit that shorts the LD cathode and anode when a signal indicating that the absolute value of the reverse voltage is large is output, the LD usage conditions such as modulation frequency can be adjusted. Highly reliable LD with LD protection function against static electricity and circuit surges
A driving circuit can be obtained. Note that optical memories, laser beam printers, etc. can be considered as application examples of the present invention.

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

第１図は、本発明の実施例によるＬＤ駆動回路ブロック
図。 第２図は、従来のＬＤの保護回路例を示す図１・・・ア
ナログスイッチ ２・・・ホトダイオード ３・・・半導体レーザ ４、　５．　６．　７・・・抵抗 ８・・・オペアンプ ９．１０．１１・・・抵抗 １２・・・基準電圧発生回路 １３・・・負荷抵抗 １４・・・基準電圧 １５・・・ＡＰＣ回路 １６・・・コンパレータ １７・・・インダクタ １８・・・キャパシタ １９・・・ＦＥＴ　（電界効果型トランジスタ）以上 出願人　セイコーエプソン株式会社 代理人弁理士　最上　務　他１名・、、、、、、Ｊ、１
．、　’：＋第１図FIG. 1 is a block diagram of an LD driving circuit according to an embodiment of the present invention. FIG. 2 shows an example of a conventional LD protection circuit. 6. 7... Resistor 8... Operational amplifier 9.10.11... Resistor 12... Reference voltage generation circuit 13... Load resistor 14... Reference voltage 15... APC circuit 16... Comparator 17...Inductor 18...Capacitor 19...FET (Field Effect Transistor) Applicant: Seiko Epson Corporation Representative Patent Attorney Tsutomu Mogami and 1 other person... J, 1
．． , ':+Figure 1

Claims (1)

【特許請求の範囲】 １）半導体レーザ（以下ＬＤとする）を駆動する回路に
おいて、 ａ）ＬＤの逆方向電圧を検出する回路と、 ｂ）ＬＤの最大逆方向電圧を設定するために必要な基準
電圧を発生する基準電圧発生回路と、ｃ）該基準電圧と
ＬＤの逆方向電圧を比較して、その大小によって出力レ
ベルの変化するコンパレータと、 ｄ）該コンパレータから前記基準電圧の絶対値よりＬＤ
の逆方向電圧の絶対値が大きいことを示す信号が出力さ
れた場合にはＬＤのカソードとアノード間を短絡する回
路からなるＬＤ保護回路を有することを特徴とするＬＤ
駆動回路。 ２）前記コンパレータがヒステリシス特性を有すること
を特徴とする第１項記載の半導体レーザ駆動回路。[Claims] 1) A circuit for driving a semiconductor laser (hereinafter referred to as LD), which includes: a) a circuit for detecting the reverse voltage of the LD; and b) a circuit necessary for setting the maximum reverse voltage of the LD. a reference voltage generation circuit that generates a reference voltage, c) a comparator that compares the reference voltage with the reverse voltage of the LD and changes the output level depending on the magnitude thereof, and d) outputs a signal from the absolute value of the reference voltage from the comparator. L.D.
An LD characterized in that it has an LD protection circuit comprising a circuit that shorts between the cathode and anode of the LD when a signal indicating that the absolute value of the reverse voltage is large is output.
drive circuit. 2) The semiconductor laser drive circuit according to item 1, wherein the comparator has hysteresis characteristics.
JP3882788A 1988-02-22 1988-02-22 Semiconductor laser driving circuit Pending JPH01214080A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP3882788A JPH01214080A (en) 1988-02-22 1988-02-22 Semiconductor laser driving circuit

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP3882788A JPH01214080A (en) 1988-02-22 1988-02-22 Semiconductor laser driving circuit

Publications (1)

Publication Number Publication Date
JPH01214080A true JPH01214080A (en) 1989-08-28

Family

ID=12536066

Family Applications (1)

Application Number Title Priority Date Filing Date
JP3882788A Pending JPH01214080A (en) 1988-02-22 1988-02-22 Semiconductor laser driving circuit

Country Status (1)

Country Link
JP (1) JPH01214080A (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0660471A2 (en) * 1993-12-27 1995-06-28 Xerox Corporation Current driven voltage sensed laser diode driver (CDVS LDD)
WO2007095325A2 (en) * 2006-02-10 2007-08-23 Intel Corporation Optoelectronic device electrostatic discharge protection
US20170170624A1 (en) * 2015-12-10 2017-06-15 Fujitsu Limited Optical amplifier and method of controlling excitation light

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0660471A2 (en) * 1993-12-27 1995-06-28 Xerox Corporation Current driven voltage sensed laser diode driver (CDVS LDD)
EP0660471A3 (en) * 1993-12-27 1995-11-29 Xerox Corp Current driven voltage sensed laser diode driver (CDVS LDD).
WO2007095325A2 (en) * 2006-02-10 2007-08-23 Intel Corporation Optoelectronic device electrostatic discharge protection
WO2007095325A3 (en) * 2006-02-10 2007-10-04 Intel Corp Optoelectronic device electrostatic discharge protection
US20170170624A1 (en) * 2015-12-10 2017-06-15 Fujitsu Limited Optical amplifier and method of controlling excitation light

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