JPS6251279A - Semiconductor-laser driving circuit - Google Patents

Semiconductor-laser driving circuit

Info

Publication number
JPS6251279A
JPS6251279A JP18938585A JP18938585A JPS6251279A JP S6251279 A JPS6251279 A JP S6251279A JP 18938585 A JP18938585 A JP 18938585A JP 18938585 A JP18938585 A JP 18938585A JP S6251279 A JPS6251279 A JP S6251279A
Authority
JP
Japan
Prior art keywords
circuit
output
semiconductor laser
voltage
laser
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
JP18938585A
Other languages
Japanese (ja)
Inventor
Toshihiko Nakazawa
利彦 中沢
Takashi Murahashi
村橋　孝
Yoshiyuki Ichihara
美幸 市原
Toshihiro Takesue
敏洋 武末
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.)
Konica Minolta Inc
Original Assignee
Konica Minolta Inc
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 Konica Minolta Inc filed Critical Konica Minolta Inc
Priority to JP18938585A priority Critical patent/JPS6251279A/en
Priority to US06/901,185 priority patent/US4771431A/en
Priority to GB8620851A priority patent/GB2179783B/en
Priority to DE3629436A priority patent/DE3629436C2/en
Publication of JPS6251279A publication Critical patent/JPS6251279A/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
    • H01S5/04—Processes or apparatus for excitation, e.g. pumping, e.g. by electron beams
    • H01S5/042—Electrical excitation ; Circuits therefor
    • 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
    • H01S5/0683—Stabilisation of laser output parameters by monitoring the optical output parameters

Landscapes

  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Optics & Photonics (AREA)
  • Dot-Matrix Printers And Others (AREA)
  • Laser Beam Printer (AREA)
  • Exposure Or Original Feeding In Electrophotography (AREA)
  • Semiconductor Lasers (AREA)

Abstract

PURPOSE:To keep the light output of a semiconductor laser constant without knowing the temperature characteristics and the like of the semiconductor laser beforehand regardless of the characteristic fluctuation of the semiconductor laser due to ambient temperature and secular change, by providing an integrating circuit, which integrates the detected light output signals and uses the result for controlling the driving of the semiconductor laser. CONSTITUTION:An integrating circuit integrates the detected light output signals and uses the result for controlling the driving of a semiconductor laser. For example, the light output of a laser diode 54 is detected by a photodiode 11 and converted into an electric signals. The signals is amplified in an operation amplifier 13. The output from the amplifier is compared with a reference voltage Vf2 in a differential circuit 3 and the difference is obtained. After the differential voltages are integrated in an integrating circuit 4, a voltage, which drives the laser diode 54, is obtained in an output circuit 5. Thus the laser diode 54 emits the light. The light output is fed back to the light detecting circuit again.

Description

【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、レーザ・ダイオード等の半導体レーザを駆動
する回路に関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a circuit for driving a semiconductor laser such as a laser diode.

〔従来技術〕[Prior art]

半導体し、−ザは、その温度によって駆動電流に対する
光出力の特性が大きく変動し、温度が高いぼど同一の光
出力を得るための駆動電流が大きくなる。For semiconductors, the characteristics of optical output with respect to driving current vary greatly depending on the temperature, and the higher the temperature, the larger the driving current required to obtain the same optical output.

このような半導体レーザをレーザ光源として使用したレ
ーザ・プリンタでは、画像書き込み時にそのレーザ出力
が一定でないと、画質を一定に保持することができず、
記録品質に問題を惹起する。In a laser printer that uses such a semiconductor laser as a laser light source, if the laser output is not constant when writing an image, the image quality cannot be maintained constant.
This causes problems in recording quality.

このようなことから、半導体レーザの光出力を、温度に
依存せず常に一定に保持できるよにした半導体レーザ駆
動回路が提案されている。これはＡＰ　Ｃ（Ａｕｔｏｍ
ａｔｉｃ　Ｐｏｗｅｒ　Ｃｏｎｔｒｏｌ）回路と呼ばれ
ている。For this reason, a semiconductor laser drive circuit has been proposed in which the optical output of the semiconductor laser can be kept constant regardless of temperature. This is AP C (Auto
atic power control) circuit.

その中の一つに、半導体レーザを定電圧で駆動する方式
のＡＰＣ回路が、半導体レーザの変調回路との組み合わ
せで用いられている。One of them is an APC circuit that drives a semiconductor laser with a constant voltage, and is used in combination with a semiconductor laser modulation circuit.

ところが、この定電圧駆動方式のＡＰＣ回路にお、いて
温度補償を行なうには、周囲湯度に応じて半導体レーザ
の駆動電圧を変化させて光出力を−定の値に保つ必要が
あり、このために例えば、温度を検知して電気信号に変
換し、その変換信号によって駆動電圧を制御する必要が
ある。However, in order to perform temperature compensation in this constant voltage drive type APC circuit, it is necessary to maintain the optical output at a constant value by changing the drive voltage of the semiconductor laser according to the ambient temperature. For this purpose, for example, it is necessary to detect temperature, convert it into an electrical signal, and control the drive voltage using the converted signal.

しかし、この方法では、予め半導体レーザの温度特性を
調査し、それに応した制御電圧を発生させる必要がある
が、半導体レーザの特性はその製品によって個々にバラ
ツキがあり、また経年変化もあるめたに、正確な温度補
償を行なうことは困難である。However, with this method, it is necessary to investigate the temperature characteristics of the semiconductor laser in advance and generate a control voltage accordingly, but the characteristics of semiconductor lasers vary depending on the product and also change over time. Therefore, it is difficult to perform accurate temperature compensation.

〔発明の目的〕[Purpose of the invention]

本発明の目的は、周囲温度や経年変化による半導体レー
ザの特性変動にも拘わらず、しかも半導体レーザの温度
特性等を予め知る必要なくして、その半導体レーザの光
出力を一定に保持できよう。An object of the present invention is to be able to maintain the optical output of a semiconductor laser at a constant level, despite variations in the characteristics of the semiconductor laser due to ambient temperature or changes over time, and without the need to know the temperature characteristics of the semiconductor laser in advance.

にすることである。It is to do so.

〔発明の構成〕[Structure of the invention]

このために本発明では、半導体レーザの発光出力を検出
し、該出力が予め定められた一定の光出力となるように
上記半導体レーザの駆動電圧或いは駆動電流を制御する
ように構成した半導体レーザ駆動回路において、上記検
出した光出力信号を積分して−に記事導体レーザ駆動制
御用とするする積分回路を具備するように構成している
。For this purpose, the present invention provides a semiconductor laser drive configured to detect the light emission output of the semiconductor laser and control the drive voltage or drive current of the semiconductor laser so that the output becomes a predetermined constant light output. The circuit is configured to include an integrating circuit that integrates the detected optical output signal and uses it for controlling the drive of the conductor laser.

〔実施例〕〔Example〕

以下、本発明の実施例について説明する。図はその一実
施例のレーザ・プリンタ用の半導体レーザの一種のレー
ザ・ダイオードの駆動回路の回路図である。Examples of the present invention will be described below. The figure is a circuit diagram of a driving circuit for a laser diode, which is a type of semiconductor laser for a laser printer, according to an embodiment of the present invention.

１は後記するレーザ・ダイオードの光出力を検出する光
出力検出回路であり、フォト・ダイオード川１と負荷抵
抗１２との共通接続点が演算増幅器１３の非反転入力端
子に接続され、反転入力端子にはその演算増幅器１３の
出力電圧を抵抗１４．１５で分圧した電圧がフィードハ
ックしている。Reference numeral 1 denotes an optical output detection circuit for detecting the optical output of a laser diode, which will be described later.The common connection point between the photo diode 1 and the load resistor 12 is connected to the non-inverting input terminal of the operational amplifier 13, and the inverting input terminal is connected to the non-inverting input terminal of the operational amplifier 13. A voltage obtained by dividing the output voltage of the operational amplifier 13 by a resistor 14.15 is feed-hacked.

従って、この光出力検出回路１では、フォト・ダイオー
ド１１で受光する光出力が大きいほど、演算増幅器１３
の非反転入力端子の電圧が大きくなって、大きな電圧を
出力する。Therefore, in this optical output detection circuit 1, the larger the optical output received by the photodiode 11, the more the operational amplifier 13
The voltage at the non-inverting input terminal of is increased and a large voltage is output.

２は基準電圧発生回路であり、固定抵抗２１と可変抵抗
２２の直列回路で構成され、可変抵抗２２の両端の電圧
は定電圧ダイオード２３により一定の電圧に保持されて
いる。そして、基準電圧は、定電圧ダイオード２３の電
圧Ｖｙｌ及び可変抵抗２２から得られる電圧Ｖ　’ｙ　
２の２種となる。2 is a reference voltage generating circuit, which is composed of a series circuit of a fixed resistor 21 and a variable resistor 22, and the voltage across the variable resistor 22 is maintained at a constant voltage by a constant voltage diode 23. The reference voltage is the voltage Vyl of the constant voltage diode 23 and the voltage V'y obtained from the variable resistor 22.
There are two types.

３は差動回路であり、演算増幅器３１とフィードバック
量を決める抵抗３２．３３で構成され、前記光出力検出
回路１の出力電圧と基準電圧発生回路２の可変抵抗２２
で得られる電圧とを比較し、その比較結果の電圧を出力
する。−即ち、ここから出力電圧は、光出力検出回路１
の出力電圧が増加すれば、減少する。基準電圧発生回路
２め可変抵抗２２の値を調整すれば、電圧Ｖ’Ｂが変゛
化し、比較基準値を変更することができ、これにより装
置間のバラツキ等を調整できる。Reference numeral 3 denotes a differential circuit, which is composed of an operational amplifier 31 and resistors 32 and 33 that determine the amount of feedback, and which connects the output voltage of the optical output detection circuit 1 and the variable resistor 22 of the reference voltage generation circuit 2.
Compare the voltage obtained with , and output the voltage of the comparison result. - That is, the output voltage from here is the optical output detection circuit 1
If the output voltage of increases, it decreases. By adjusting the value of the variable resistor 22 of the second reference voltage generation circuit, the voltage V'B changes, and the comparison reference value can be changed, thereby making it possible to adjust variations between devices.

４ば本発明の要部を構成する積分回路□であり′、演算
増幅器４１、その演算増幅□器４１の出力端子と反転入
力端子との間に接続されたコンデンサ４２及び反転入力
端子に接続される抵抗４３とで構成され、その抵抗４３
には前段の差動回路３の出力電圧が印加し、演算増幅器
４１の非反転入力端子には基準電圧Ｖｆｌが印加してい
る。4 is an integrating circuit □ which constitutes a main part of the present invention, and includes an operational amplifier 41, a capacitor 42 connected between the output terminal of the operational amplifier □ 41 and an inverting input terminal, and an inverting input terminal. The resistor 43
The output voltage of the differential circuit 3 at the previous stage is applied to the differential circuit 3, and the reference voltage Vfl is applied to the non-inverting input terminal of the operational amplifier 41.

この積分回路は、差動回路３の出力電圧と基準電圧ｖｆ
ｌとの差の電圧を時間的に積分するよう動作し、両型圧
が一致すると出力電圧は零となる。This integrating circuit combines the output voltage of the differential circuit 3 and the reference voltage vf.
It operates so as to temporally integrate the voltage difference between the two types, and when the two pressures match, the output voltage becomes zero.

即ち、ここでは、上記検出した光出力信号を積分し□て
レーザ・ダイオード駆動制御用としている。That is, here, the detected optical output signal is integrated and used for laser diode drive control.

５は出力回路であり、基準電圧Ｖｆｌを非反転入力端子
に入力し反転入力端子には積分回路４からの出力電圧を
入力する演算増幅器５１、その演算増幅器５１の出力電
圧により抵抗５２を介して制御される出力トランジスタ
５３、そのトランジスタ５３により電源番供給されるレ
ーザ・ダイオード５４、そのレーザ・ダイオード５４へ
の電源供給状態を演算増幅器５１にフィード・バンクす
る抵抗５５．５“６、竿のレーザ・ダイオード５４の負
荷抵抗５７、及び変調回路６からの変調出力電圧によっ
てレーザ・ダイオード５４を変調（オン・オフ）させる
変調用トランジスタにより構成されている。5 is an output circuit, which includes an operational amplifier 51 which inputs the reference voltage Vfl to its non-inverting input terminal and inputs the output voltage from the integrating circuit 4 to its inverting input terminal; A controlled output transistor 53, a laser diode 54 which is powered by the transistor 53, a resistor 55.5"6 which feeds the power supply state of the laser diode 54 to the operational amplifier 51, and a laser in the pole. - Consists of a load resistor 57 of the diode 54 and a modulation transistor that modulates (turns on/off) the laser diode 54 with the modulated output voltage from the modulation circuit 6.

また、このレーザ・ダイオード５４はそこから発射され
るレーザ光の一部が前記したフォト・ダイオードＩＩに
人力するように光結合されている。Further, this laser diode 54 is optically coupled so that a portion of the laser light emitted therefrom is transmitted to the photodiode II described above.

更に、このフォト・ダイオード１１の電源としては、出
力トランジスタ５３の出力電圧が使用されている。Further, as a power source for this photodiode 11, the output voltage of the output transistor 53 is used.

さて、レーザ・ダイオード５４の光出力はフォト・ダイ
オード１１によって検出されて電気信号に変換され、演
算増幅器１３で増幅される。そして、ここからの出力は
、差動回路３において基準電圧ｖ１□と比較されてその
差が求められ、その差電圧が積分回路４で積分された後
に、出力回路５においてレニザ・ダイオード５４を駆動
する電圧となって、レーザ・ダイオード５４を発光させ
る。Now, the optical output of the laser diode 54 is detected by the photo diode 11, converted into an electrical signal, and amplified by the operational amplifier 13. Then, the output from this is compared with the reference voltage v1□ in the differential circuit 3 to find the difference, and after the difference voltage is integrated in the integrating circuit 4, the output circuit 5 drives the Renizer diode 54. The voltage becomes such that the laser diode 54 emits light.

そして、その光出力は再度光検出回路にフィードバック
される。Then, the optical output is fed back to the photodetection circuit again.

ここで、レーザプリンタのスタンバイ時（書込み待機中
）には、積分コンデンサ４２には予め適当な電圧が充電
されており、その出力はレーザ・ダイオード５４を点灯
させるに十分な電圧であるとする。このとき、変調用ト
ランジスタ５８はオフである。Here, it is assumed that when the laser printer is on standby (waiting for writing), the integrating capacitor 42 is charged with an appropriate voltage in advance, and its output is a voltage sufficient to light the laser diode 54. At this time, the modulation transistor 58 is off.

しかる後に、トランジスタ５８をオンさせてレーザ・ダ
イオード５４を点灯させると、光出力はフォト・ダイオ
ード１１によって検出され、光出力検出回路１の出力電
圧が上がるので、差動回路３の出力電圧が減少する。こ
の結果、積分回路４の出力が変化し、光出力が変化する
。After that, when the transistor 58 is turned on and the laser diode 54 is turned on, the optical output is detected by the photodiode 11, and the output voltage of the optical output detection circuit 1 increases, so that the output voltage of the differential circuit 3 decreases. do. As a result, the output of the integrating circuit 4 changes, and the optical output changes.

この動作は、差動回路３の出力電圧と積分回路４の演算
−幅器４１の非反転入力端子の電圧が一致するまで継続
し、一致した時点で光出力は一定に制御される。This operation continues until the output voltage of the differential circuit 3 and the voltage at the non-inverting input terminal of the arithmetic unit 41 of the integrating circuit 4 match, and at the time they match, the optical output is controlled to be constant.

このとき、レーザ・ダイオード５４以外の回路部品、の
温度特性を無視できれば、温度に依らず、光出力が予め
基準電圧発生回路２で定められた値になるまで積分回路
４が動作を続けるために、温度の影響を受けずに光出力
を常に一定に保持することができる。At this time, if the temperature characteristics of circuit components other than the laser diode 54 can be ignored, the integrating circuit 4 will continue to operate regardless of temperature until the optical output reaches a value predetermined by the reference voltage generating circuit 2. , the light output can always be kept constant without being affected by temperature.

ちなみに、図の回路で積分回路４を削除した場合には、
フォト・ダイオード１１で検出される光検出信号と出力
回路５に印加する電圧とが比例関係となるので、レーザ
・ダイオード５４の光出力を基準電圧■ｆｌに対応した
目標値に制御することができない場合がある。即ち、例
えばレーザ・ダイオード５４の光出力は、それが同一で
あっても、そのダイオード５４の温度が高い場合と低い
場合を比較すると、前者の方がより多くの駆動電流を流
す必要があるが、上記積分回路４を削除したループでは
このような細かい制御は不可能である。By the way, if you delete integrating circuit 4 in the circuit shown in the figure,
Since the photodetection signal detected by the photodiode 11 and the voltage applied to the output circuit 5 are in a proportional relationship, the optical output of the laser diode 54 cannot be controlled to the target value corresponding to the reference voltage ■fl. There are cases. That is, for example, even if the optical output of the laser diode 54 is the same, if you compare the case where the temperature of the diode 54 is high and the case where it is low, the former requires more drive current to flow. , such fine control is not possible with a loop in which the integration circuit 4 is removed.

積分回路４を使用することにより、このような問題点は
解消される。これは、経年変化によるレーザ・ダイオー
ド５４の光出力変動に対しても同様である。By using the integrating circuit 4, such problems can be solved. This also applies to fluctuations in the optical output of the laser diode 54 due to aging.

〔発明の効果〕〔Effect of the invention〕

以上から本発明によれば、半導体レーザの光出力を温度
や経年変化等に拘わらず一定の状態に保持することがで
き、このとき温度特性やその温度を検知する手段は全く
不要となる。As described above, according to the present invention, the optical output of a semiconductor laser can be maintained in a constant state regardless of temperature, aging, etc., and at this time, temperature characteristics and means for detecting the temperature are completely unnecessary.

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

図は本発明の一実施例のレーザ・ダイオードの駆動回路
の回路図である。 １・・・光出力検出回路、２・・・基準電圧発生回路、
３・・・差動回路、４・・・積分回路、５・・・出力回
路、１１・・・フォト・ダイオード、５４・・・レーザ
・ダイオード。The figure is a circuit diagram of a laser diode drive circuit according to an embodiment of the present invention. 1... Optical output detection circuit, 2... Reference voltage generation circuit,
3... Differential circuit, 4... Integrating circuit, 5... Output circuit, 11... Photo diode, 54... Laser diode.

Claims (2)

【特許請求の範囲】[Claims] （１）．半導体レーザの発光出力を検出し、該出力が予
め定められた一定の光出力となるように上記半導体レー
ザの駆動電圧或いは駆動電流を制御するように構成した
半導体レーザ駆動回路において、上記検出した光出力信
号を積分して上記半導体レーザ駆動制御用とする積分回
路を具備することを特徴とする半導体レーザ駆動回路。(1). In a semiconductor laser drive circuit configured to detect the light emission output of a semiconductor laser and control the drive voltage or drive current of the semiconductor laser so that the output becomes a predetermined constant light output, the detected light A semiconductor laser drive circuit comprising an integration circuit that integrates an output signal to control the drive of the semiconductor laser. （２）．上記積分回路を、上記検出した光出力に対応す
る電圧と上記一定の光出力に対応する基準電圧との差を
積分するように構成したことを特徴とする特許請求の範
囲第１項記載の半導体レーザ駆動回路。(2). The semiconductor according to claim 1, wherein the integrating circuit is configured to integrate a difference between a voltage corresponding to the detected optical output and a reference voltage corresponding to the constant optical output. Laser drive circuit.
JP18938585A 1985-08-30 1985-08-30 Semiconductor-laser driving circuit Pending JPS6251279A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
JP18938585A JPS6251279A (en) 1985-08-30 1985-08-30 Semiconductor-laser driving circuit
US06/901,185 US4771431A (en) 1985-08-30 1986-08-27 Semiconductor laser drive
GB8620851A GB2179783B (en) 1985-08-30 1986-08-28 Semiconductor laser driver
DE3629436A DE3629436C2 (en) 1985-08-30 1986-08-29 Driver stage for semiconductor lasers

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP18938585A JPS6251279A (en) 1985-08-30 1985-08-30 Semiconductor-laser driving circuit

Publications (1)

Publication Number Publication Date
JPS6251279A true JPS6251279A (en) 1987-03-05

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Family Applications (1)

Application Number Title Priority Date Filing Date
JP18938585A Pending JPS6251279A (en) 1985-08-30 1985-08-30 Semiconductor-laser driving circuit

Country Status (1)

Country Link
JP (1) JPS6251279A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5021733A (en) * 1989-11-02 1991-06-04 Mitsubishi Denki Kabushiki Kaisha Burn-in apparatus

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS58141045A (en) * 1982-02-16 1983-08-22 Toshiba Corp Driving circuit for semiconductor laser diode

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS58141045A (en) * 1982-02-16 1983-08-22 Toshiba Corp Driving circuit for semiconductor laser diode

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5021733A (en) * 1989-11-02 1991-06-04 Mitsubishi Denki Kabushiki Kaisha Burn-in apparatus

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