JPS63184934A - Light output stabilizing circuit - Google Patents
Light output stabilizing circuitInfo
- Publication number
- JPS63184934A JPS63184934A JP62016987A JP1698787A JPS63184934A JP S63184934 A JPS63184934 A JP S63184934A JP 62016987 A JP62016987 A JP 62016987A JP 1698787 A JP1698787 A JP 1698787A JP S63184934 A JPS63184934 A JP S63184934A
- Authority
- JP
- Japan
- Prior art keywords
- semiconductor laser
- signal
- output
- current
- light
- 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
- 230000000087 stabilizing effect Effects 0.000 title claims description 10
- 239000004065 semiconductor Substances 0.000 claims abstract description 36
- 230000003287 optical effect Effects 0.000 claims description 24
- 230000006866 deterioration Effects 0.000 abstract description 12
- 238000010586 diagram Methods 0.000 description 6
- 230000000694 effects Effects 0.000 description 2
- 239000003990 capacitor Substances 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 230000003449 preventive effect Effects 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
- G11B7/125—Optical beam sources therefor, e.g. laser control circuitry specially adapted for optical storage devices; Modulators, e.g. means for controlling the size or intensity of optical spots or optical traces
- G11B7/126—Circuits, methods or arrangements for laser control or stabilisation
Landscapes
- Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Optical Head (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、光デイスクメモリ装置等に使用する光出力安
定化回路に関する。DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical output stabilizing circuit used in optical disk memory devices and the like.
従来の技術
第３図は従来の光源装置の一部をｆｆ’？成する光出力
安定化回路を示しており、第４図の半導体レーザの特性
図を用いて動作を説明する。第３図において１は半導体
レーザ（ＬＤ）、２はフォトダイオード（ＰＤ）、３は
光信号を電気信号に変換する増幅器、４は増幅器、５は
前記電気信号を保持するためのアンプ抵抗、コンデンサ
を備えた増幅器、６は記録時に増幅器３が飽和しないよ
う（こ動作点を設定するための電流源、１１は、記録信
号で半導体レーザ１を駆動する増幅器、ａは記録信号、
ｄは記録時ゲート信号、ｅは再生時ゲート信号、ＳＷ２
、ＳＷ３、ＳＷ４、ＳＷ５は前記ゲート信号で開閉する
スイッチである。BACKGROUND ART FIG. 3 shows a part of a conventional light source device. The operation of the optical output stabilizing circuit will be explained using the characteristic diagram of the semiconductor laser shown in FIG. In FIG. 3, 1 is a semiconductor laser (LD), 2 is a photodiode (PD), 3 is an amplifier that converts an optical signal into an electrical signal, 4 is an amplifier, and 5 is an amplifier resistor and a capacitor for holding the electrical signal. 6 is a current source for setting the operating point so that the amplifier 3 is not saturated during recording; 11 is an amplifier that drives the semiconductor laser 1 with a recording signal; a is a recording signal;
d is a gate signal during recording, e is a gate signal during playback, SW2
, SW3, SW4, and SW5 are switches that are opened and closed by the gate signal.
次に上記従来例の動作について説明する。第３図におい
て再生時は再生時ゲート信号ｅが有効であり、スイッチ
ＳＷ３、ＳＷ４が閉じており、半導体レーザ１の光出力
が一定となる様にＡＰＣ（自動光出力コントロール）回
路を構成しており、第４図の半導体レーザ１の電流・光
出力特性の０１番こおいて、電流値１８．にバイアスさ
れ、半導体レーザ１の光出力は再生光出力Ｐ２で発光し
ており、また、保持回路５は、記録時にもこのバイアス
値を保持するよう動作する。記録時には記録時ゲート信
号ｄが有効となり、スイッチＳＷ３、ＳＷ４は開き、逆
（こスイッチＳＷ２、ＳＷ５が閉じて半導体レーザ１は
バイアス電流値’Ｂ１にバイアスされ、記録信号ａが入
力されると、駆動回路の増幅器１１で電流増幅され、パ
ルス電流’Ｐ１が重畳され、記録光出力Ｐｗで半導体レ
ーザ１が発光する。ここで温度変動の影響により半導体
レーザ１の閾値電流値力曲 から’ｔｈ２’こ変化し
、Ｃ４２ｈｌ
のカーブのように変化したとすると、再生時のＡＰＣ回
路の働きにより、バイアスの電流値が１ 番こ変化し
、再生光出力ＰＲは一定となり、日２
また記録時は保持回路５の働きにより、バイアスの電流
値１ にパルス電流’Ｐ、が重畳され、記録光出力Ｐ
ｗが得られる。Next, the operation of the above conventional example will be explained. In FIG. 3, the APC (automatic optical output control) circuit is configured so that during reproduction, the reproduction gate signal e is valid, the switches SW3 and SW4 are closed, and the optical output of the semiconductor laser 1 is constant. 4, the current value is 18. The semiconductor laser 1 emits light at a reproduction light output P2, and the holding circuit 5 operates to hold this bias value even during recording. During recording, the recording gate signal d becomes valid, switches SW3 and SW4 are opened, and vice versa (switches SW2 and SW5 are closed and the semiconductor laser 1 is biased to the bias current value 'B1, and when the recording signal a is input, The current is amplified by the amplifier 11 of the drive circuit, the pulse current 'P1 is superimposed, and the semiconductor laser 1 emits light with the recording light output Pw.Here, due to the influence of temperature fluctuation, the threshold current value of the semiconductor laser 1 changes from 'th2' to 'th2'. If this changes as shown in the curve of C42hl, the bias current value will change by 1 due to the action of the APC circuit during playback, the playback light output PR will remain constant, and 2nd and during recording will be retained. Due to the function of the circuit 5, a pulse current 'P' is superimposed on the bias current value 1, and the recording light output P is
w is obtained.
このよう（こ上記従来の光出力安定化回路でも、半導体
レーザの閾値電流値の変化、劣化に対して、最適な再生
光出力、記録光出力を得ることができる。Even with the conventional optical output stabilizing circuit described above, it is possible to obtain optimal reproduction optical output and recording optical output against changes and deterioration of the threshold current value of the semiconductor laser.
発明が解決しようとする問題点
しかしながら、上記従来の光出力安定化回路では、記録
時に一定のパルス電流を重畳する方法であるため、半導
体レーザの特性変化、劣化番こ対してフィードバックが
かからず、長年使用している間に徐々にではあるが半導
体レーザの効率、特に外部微分量子効率が劣化し、第４
図の０２の様になった場合、再生光出力ＰＲは一定（こ
保たれるが、記録光出力がＰ ◆こ低下してしまう、
という間 ａ
照点があった。Problems to be Solved by the Invention However, in the conventional optical output stabilizing circuit described above, since a constant pulse current is superimposed during recording, no feedback is provided in response to changes in the characteristics and deterioration of the semiconductor laser. After many years of use, the efficiency of the semiconductor laser, especially the external differential quantum efficiency, gradually deteriorates, and the fourth
In the case shown in 02 in the figure, the reproduction light output PR is kept constant, but the recording light output decreases.
During that time, there was a point of view.
本発明はこのような従来の問題を解決するものであり、
半導体レーザの経時的な劣化に対して、常に最適な再生
光出力、記録光出力を得ることができる優れた光出力安
定化回路を提供することを目的とするものである。The present invention solves these conventional problems,
It is an object of the present invention to provide an excellent optical output stabilizing circuit that can always obtain optimal reproduction optical output and recording optical output against the deterioration of semiconductor lasers over time.
問題点を解決するための手段
本発明は上記目的を達成するために、信号電流とは別に
、チェック信号を印加し半導体レーザをチェック発光さ
せ、これをモニタする受光素子の出力によりａ＋Ｕ定し
、その出力をあらかじめ定めた基準値と比較し、その結
果Ｑこ基づき前記半導体レーザの駆動電流の値を設定出
来るように構成したものである。Means for Solving the Problems In order to achieve the above object, the present invention applies a check signal in addition to the signal current to cause the semiconductor laser to emit check light, and determines a+U based on the output of a light receiving element that monitors this. The output is compared with a predetermined reference value, and the value of the driving current of the semiconductor laser can be set based on the resultant Q.
作 用
従って本発明によれば、光ディスク等の光源の長期的特
性劣化を実際の使用に先立ってテスト発光※こより測定
し、駆動電流の補償設定が行える等の効果を有する。According to the present invention, the long-term characteristic deterioration of a light source such as an optical disk can be measured by test emission* prior to actual use, and drive current compensation can be set.
実施例
第１図は本発明の一実施例の構成を示すものである。第
１図において、第３図と同一番号を付しであるものは同
一名称を表わすものとする。７は信号電流の可変増幅器
、８は比較器、９はゲート回路、１０は計数回路、ＳＷ
ｌはチェック信号と記録信号を切換えるスイッチ、ｂは
チェック信号、Ｃは計数回路１０をリセットするリセッ
ト信号である。Embodiment FIG. 1 shows the configuration of an embodiment of the present invention. In FIG. 1, the same numbers as in FIG. 3 represent the same names. 7 is a variable amplifier for signal current, 8 is a comparator, 9 is a gate circuit, 10 is a counting circuit, SW
1 is a switch for switching between a check signal and a recording signal, b is a check signal, and C is a reset signal for resetting the counting circuit 10.
次に上記実施例の動作について説明する。上記実施例に
おいて、再生時、および記録時の動作は従来例と同様で
ある。ここで、従来例では解決できなかった、第４図の
０２のような光出力特性に劣化した半導体レーザの場合
について第１図、第２図を用いて説明する。Next, the operation of the above embodiment will be explained. In the above embodiment, the operations during reproduction and recording are similar to those of the conventional example. Here, the case of a semiconductor laser having deteriorated optical output characteristics as shown in 02 in FIG. 4, which could not be solved in the conventional example, will be explained with reference to FIGS. 1 and 2.
半導体レーザ１の特性劣化は急激に起こるものではなく
、長い時間使用している間に徐々台こ起こるものであり
、１単位の信号の記録、たとえば１セクタや１トラツク
の記録時間の間に劣化するものではない。従って光デイ
スク装置に電源が投入された際のイニシャライズ動作の
一部として、あるいは、ドライブ装置の媒体を入れ換え
る時などに、半導体レーザを記録光出力で動作させる前
（こ、半導体レーザの外部微分量子効率の劣化を検出し
、駆動電流を制御することにより補償を行う。第１図に
おいて、半導体レーザ１の劣化チェック時は、スイッチ
ＳＷＩ は下側（チェック信号すの入力側）に切換えら
れている。そしてまず、リセット信号Ｃにより、計数回
路１０がリセットされ、信号電流の可変増幅器７のゲイ
ンを最小の初期状態にセットする。この状態では再生時
ゲート信号ｅが有効であり、スイッチＳＷ３、ＳＷ４が
閉じ、半導体レーザーは、第２図の０２特性において、
再生光出力Ｐ で発光するよう電流値１８２０こバイア
スに
されＡＰＣ動作している。そしてチェック信号すが人力
されると、これに連動して記録時ゲート信号ｄが有効と
なり、今度はスイッチＳＷ２、ＳＷ５が閉じ、保持回路
５により電流値１８２にバイアスされた状態を保ち、チ
ェック信号ｂ＋こより、パルス電流’ＰＩが重畳され、
半導体レーザーが出力Ｐｗａで発光する。その光出力を
フォトダイオード２で検出し、光出力に比例した光電流
として取り出し、増幅器３で電圧信号Ｇこ変換され、こ
れを比較器８で、適正発光出力に対する基準電圧ｒｅｆ
と比較し、基準電圧ｒｅｆに達していないと比較器８
の出力はハイ（Ｈｉｇｈ） となり、ゲート回路９番
こより、チェック信号すが出ている時、計数回路１０を
計数可能の状態とし、チェック信号すがオフとなる立下
りエツジを計数入力として、計数を行なう。そして、こ
れにより信号電流の可変増幅器７のゲインが大きく設定
され、パルス電流がΔｌＰだけ増す。チェック信号すが
オフとなると、スイッチＳＷ３とＳＷ４が閉じ、再生光
出力ＰＲとなるようＡＰＣ動作する。次にチェック信号
すが入力されると、回路は保持側に切換り、パルス電流
がΔＩＰだけ増えてバイアス電流に重畳される。そして
チェック信号すによる発光出力が記録光出力ＰＷに達す
ると、比較器８の出力はロー（Ｌｏｗ）となり、ゲート
回路９により、計数回路１ｏは、チェック信号がオフと
なった場合でも計数をしない。そして、比較器８の出力
がチェック信号入力時にローであることにより、半導体
レーザ１の外部微分量子効率の劣化に対する補償動作の
設定の終了を検出し、チェック動作を終了し、スイッチ
ＳＷＩ は、記録信号ａ側Ｏこ切換えられる。そして、
この設定は、電源がオフとされるまで、又は、媒体を交
換して次の設定動作に入るまで保持される。一方、もし
、上記チェック信号すによるテスト発光の繰り返しを続
け、計数回路１ｏの計数上限値に達しても、比較器８の
出力がローとならない場合は、半導体レーザの劣化が進
み、交換の必要があると判断できる。Deterioration of the characteristics of the semiconductor laser 1 does not occur suddenly, but occurs gradually over a long period of time, and deterioration occurs during the recording of one unit of signal, for example, the recording time of one sector or one track. It's not something you do. Therefore, as part of the initialization operation when the power is turned on to the optical disk device, or when replacing the medium in the drive device, before operating the semiconductor laser with recording light output (this is the external differential quantum Deterioration in efficiency is detected and compensation is performed by controlling the drive current.In Figure 1, when checking the deterioration of the semiconductor laser 1, the switch SWI is switched to the lower side (input side of the check signal). First, the counting circuit 10 is reset by the reset signal C, and the gain of the variable amplifier 7 for the signal current is set to the minimum initial state.In this state, the gate signal e is valid during reproduction, and the switches SW3 and SW4 are activated. is closed, and the semiconductor laser has the 02 characteristic in Fig. 2,
APC operation is performed with a current value of 1820 biased so as to emit light with a reproduced light output P. Then, when the check signal is inputted manually, the gate signal d becomes valid during recording in conjunction with this, switches SW2 and SW5 are closed, the current value is kept biased to 182 by the holding circuit 5, and the check signal is From b+, pulse current 'PI is superimposed,
A semiconductor laser emits light with an output Pwa. The optical output is detected by a photodiode 2, extracted as a photocurrent proportional to the optical output, and converted into a voltage signal G by an amplifier 3. This is converted into a voltage signal G by a comparator 8, which is converted into a reference voltage ref for an appropriate light emission output.
If the reference voltage ref has not been reached, the comparator 8
When the output becomes high and the check signal is output from gate circuit No. 9, the counting circuit 10 is enabled for counting, and the falling edge at which the check signal turns off is used as the counting input to perform counting. Do this. As a result, the gain of the variable signal current amplifier 7 is set to a large value, and the pulse current increases by ΔlP. When the check signal S is turned off, the switches SW3 and SW4 are closed, and the APC operation is performed so that the reproduced light output becomes PR. Next, when the check signal S is input, the circuit switches to the holding side, and the pulse current increases by ΔIP and is superimposed on the bias current. When the light emission output due to the check signal S reaches the recording light output PW, the output of the comparator 8 becomes low, and the gate circuit 9 causes the counting circuit 1o to not perform counting even when the check signal is turned off. . Then, since the output of the comparator 8 is low when the check signal is input, it is detected that the setting of the compensation operation for the deterioration of the external differential quantum efficiency of the semiconductor laser 1 is completed, the check operation is completed, and the switch SWI starts recording. The signal a side is switched to O. and,
This setting is maintained until the power is turned off or the medium is replaced and the next setting operation is started. On the other hand, if the output of the comparator 8 does not become low even if the test emission by the above-mentioned check signal continues to be repeated and the count limit of the counting circuit 1o is reached, the semiconductor laser has deteriorated and needs to be replaced. It can be determined that there is.
発明の効果
本発明は、上記実施例より明らかなように、以下に示す
効果を有する。Effects of the Invention As is clear from the above examples, the present invention has the following effects.
（１）電源投入後の装置の初期化の際Ｑこ、又は媒体の
交換時にチェック信号により半導体レーザの劣化チェッ
ク、補償設定を行なうので、媒体に記録する時は常に最
適な記録光出力で発光させることができる。(1) When the device is initialized after the power is turned on, or when replacing the medium, the semiconductor laser is checked for deterioration and compensation settings are performed using a check signal, so when recording on the medium, it always emits light at the optimal recording light output. can be done.
＜２１ 記録信号に比べて、チェック信号は非常に低
速ですむため、検出・補償のために回路を広帯域化せず
昏こ構成することができる。<21 Compared to the recording signal, the check signal requires a very low speed, so it is possible to configure the circuit for detection and compensation without widening the band.
（３）補償回路を設けることにより、正しく記録光出力
の設定ができなかった場合には、半導体レーザの寿命と
して判断することができ、予防保守を行なうことができ
る。(3) By providing a compensation circuit, if the recording light output cannot be set correctly, it can be determined that the semiconductor laser has reached its end of life, and preventive maintenance can be performed.
第１図は本発明の一実施例における光出力安定化回路の
ブロック図、第２図は同回路の動作を説明するための半
導体レーザの電流・光出力の特性図、第３図は従来の光
出力安定化回路のブロック図、第４図は同回路の動作を
説明するための半導体レーザの電流・光出力の特性図で
ある。
１・・・・・・半導体レーザ、２・・・・フォトダイオ
ード、３ ・・・・増幅器、４・・・・・増幅器、５・
・・・増幅器、６・・・・・電流源、７・・・可変増幅
器、８ ・・・比較器、９・・・・ゲート回路、１０・
・・・計数回路、１１・・・・増幅器、ＳＷ１〜ＳＷ５
・・・・・・スイッチ、ａ・・・・記録信号、ｂ・・・
・・・チェック信号、Ｃ・・・・・リセット信号、ｄ・
・・・・・記録時ゲート信号、Ｃ・・・再生時ゲート信
号。
代理人の氏名 弁理士 中 尾 敏 男 はか１名第２
図
第４図Fig. 1 is a block diagram of an optical output stabilizing circuit according to an embodiment of the present invention, Fig. 2 is a characteristic diagram of current and optical output of a semiconductor laser to explain the operation of the circuit, and Fig. 3 is a diagram of a conventional optical output stabilizing circuit. FIG. 4, a block diagram of the optical output stabilizing circuit, is a characteristic diagram of current and optical output of a semiconductor laser for explaining the operation of the circuit. 1...Semiconductor laser, 2...Photodiode, 3...Amplifier, 4...Amplifier, 5...
...Amplifier, 6...Current source, 7...Variable amplifier, 8...Comparator, 9...Gate circuit, 10...
...Counting circuit, 11...Amplifier, SW1 to SW5
...Switch, a...Record signal, b...
...check signal, C....reset signal, d.
...Gate signal during recording, C...Gate signal during playback. Name of agent: Patent attorney Toshio Nakao (1st person, 2nd person)
Figure 4
Claims (1)
導体レーザに印加し、前記半導体レーザの発光を受光素
子でモニタし、前記受光素子の出力により前記駆動電流
を制御するようにフィードバックして自動光出力コント
ロール回路を形成し、試験時に前記信号電流に代えてよ
り低速のチェックパルス電流を印加し、この時の受光素
子の出力を基準値と比較し、その出力を計数回路を介し
て計測し、その結果により前記駆動電流を可変制御する
ことにより半導体レーザの特性補償を行うようにした光
出力安定化回路。A signal current is superimposed on a bias current and applied to the semiconductor laser as a drive current, the light emission of the semiconductor laser is monitored by a light receiving element, and the output of the light receiving element is fed back to control the drive current to automatically output light. Form a control circuit, apply a slower check pulse current instead of the signal current during the test, compare the output of the light receiving element at this time with a reference value, measure the output via a counting circuit, and An optical output stabilizing circuit that compensates for the characteristics of a semiconductor laser by variably controlling the driving current according to the result.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62016987A JPS63184934A (en) | 1987-01-27 | 1987-01-27 | Light output stabilizing circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62016987A JPS63184934A (en) | 1987-01-27 | 1987-01-27 | Light output stabilizing circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS63184934A true JPS63184934A (en) | 1988-07-30 |
Family
ID=11931385
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62016987A Pending JPS63184934A (en) | 1987-01-27 | 1987-01-27 | Light output stabilizing circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS63184934A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02103741A (en) * | 1988-10-11 | 1990-04-16 | Canon Inc | Optical information recording and reproducing device |
| EP0478275A2 (en) * | 1990-09-27 | 1992-04-01 | International Business Machines Corporation | A method of and apparatus for controlling laser power in an optical disk drive |
| JPH1064098A (en) * | 1997-07-14 | 1998-03-06 | Canon Inc | Optical information recording and reproducing device |
| JP2005129832A (en) * | 2003-10-27 | 2005-05-19 | Daitron Technology Co Ltd | Method of driving and driving apparatus for laser-diode element |
-
1987
- 1987-01-27 JP JP62016987A patent/JPS63184934A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02103741A (en) * | 1988-10-11 | 1990-04-16 | Canon Inc | Optical information recording and reproducing device |
| EP0478275A2 (en) * | 1990-09-27 | 1992-04-01 | International Business Machines Corporation | A method of and apparatus for controlling laser power in an optical disk drive |
| EP0478275A3 (en) * | 1990-09-27 | 1992-08-05 | International Business Machines Corporation | A method of and apparatus for controlling laser power in an optical disk drive |
| JPH1064098A (en) * | 1997-07-14 | 1998-03-06 | Canon Inc | Optical information recording and reproducing device |
| JP2005129832A (en) * | 2003-10-27 | 2005-05-19 | Daitron Technology Co Ltd | Method of driving and driving apparatus for laser-diode element |
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