JPH01214080A - Semiconductor laser driving circuit - Google Patents
Semiconductor laser driving circuitInfo
- 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
Links
- 239000004065 semiconductor Substances 0.000 title claims abstract description 6
- 230000005611 electricity Effects 0.000 abstract description 3
- 230000003068 static effect Effects 0.000 abstract description 3
- 230000001681 protective effect Effects 0.000 abstract 3
- 230000006870 function Effects 0.000 description 3
- 230000005669 field effect Effects 0.000 description 2
- 239000003990 capacitor Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000015654 memory Effects 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
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
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.
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)
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.
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)
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 |
-
1988
- 1988-02-22 JP JP3882788A patent/JPH01214080A/en active Pending
Cited By (5)
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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