JPH01296439A - Semiconductor laser control circuit - Google Patents
Semiconductor laser control circuitInfo
- Publication number
- JPH01296439A JPH01296439A JP63126496A JP12649688A JPH01296439A JP H01296439 A JPH01296439 A JP H01296439A JP 63126496 A JP63126496 A JP 63126496A JP 12649688 A JP12649688 A JP 12649688A JP H01296439 A JPH01296439 A JP H01296439A
- Authority
- JP
- Japan
- Prior art keywords
- current source
- comparator
- semiconductor laser
- recording
- erasing
- 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 30
- 230000003287 optical effect Effects 0.000 claims abstract description 8
- 230000001678 irradiating effect Effects 0.000 claims 1
- 238000010586 diagram Methods 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 230000008929 regeneration Effects 0.000 description 3
- 238000011069 regeneration method Methods 0.000 description 3
- 239000003990 capacitor Substances 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000001514 detection method Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 230000010355 oscillation Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 239000002023 wood Substances 0.000 description 1
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Abstract
Description
【発明の詳細な説明】
産業上の利用分野
本発明は、半導体レーザから射出させたレーザ光束を対
物レンズにより光ディスク等の光記録媒体上に集光照射
し、情報の記録、再生又は消去を行う光情報記録再生装
置における半導体レーザ制御回路に関する。DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention focuses and irradiates a laser beam emitted from a semiconductor laser onto an optical recording medium such as an optical disk using an objective lens, thereby recording, reproducing, or erasing information. The present invention relates to a semiconductor laser control circuit in an optical information recording/reproducing device.
従来の技術
一般に、光デイスク装置では記録／再生／消去用の光源
として、半導体レーザが使われる傾向にある。ここに、
半導体レーザは環境温度や自己発熱等により発光出力特
性が変動する。そこで、半導体レーザを光源として用い
て記録／再生／消去動作を行う際には、各々のモードに
応じて最適なる発光状態となる記録パワー／再生パワー
／消去パワーで動作するように、その駆動を制御する必
要がある。特に、安定した記録／再生／消去動作を行う
ためには、このように半導体レーザパワーの制御を高速
かつ高精度に行う必要もある。2. Description of the Related Art In general, optical disk devices tend to use semiconductor lasers as light sources for recording/reproducing/erasing. Here,
The light emitting output characteristics of semiconductor lasers fluctuate depending on environmental temperature, self-heating, etc. Therefore, when recording/reproducing/erasing operations are performed using a semiconductor laser as a light source, its drive must be controlled so that it operates at the recording power/reproducing power/erasing power that provides the optimum light emission state according to each mode. need to be controlled. In particular, in order to perform stable recording/reproducing/erasing operations, it is necessary to control the semiconductor laser power in this way at high speed and with high precision.
このようなことから、例えば特開昭５８−９４１４３号
公報に示されるような半導体レーザ制御方法が提案され
ている。まず、再生時には半導体レーザの出射光をモニ
ターし、所定の再生パワーとなるように制御する。また
、記録又は消去時には再生パワー時の電流値を保持して
おき、この電流値に予め設定された所定の電流を重畳し
て所定の記録パワー（又は、消去パワー）とするもので
ある。For this reason, a semiconductor laser control method has been proposed, for example, as disclosed in Japanese Unexamined Patent Publication No. 58-94143. First, during reproduction, the emitted light from the semiconductor laser is monitored and controlled to a predetermined reproduction power. Further, during recording or erasing, the current value at the read power is held, and a predetermined current set in advance is superimposed on this current value to obtain a predetermined recording power (or erasing power).
発明が解決しようとする問題点
ところが、同公報記載の制御方式では、再生パワー用の
電流値を保持するための保持回路が、再生時に使用する
制御ループ中に挿入されており、再生時の制御速度をあ
まり上げることができない。Problems to be Solved by the Invention However, in the control method described in the publication, a holding circuit for holding the current value for the reproduction power is inserted into the control loop used during reproduction, and the control method during reproduction is I can't increase the speed very much.
ちなみに、制御速度を落さないと制御系の発振という問
題を生ずる。特に、保持回路にコンデンサを用いたサン
プルホールド回路構成とした場合には、保持時間を長く
するためにコンデンサ容量が大きくされるので、制御速
度が遅くなるという欠点が増長されやすい。Incidentally, if the control speed is not reduced, the problem of oscillation of the control system will occur. In particular, in the case of a sample-and-hold circuit configuration in which a capacitor is used in the holding circuit, the capacitance of the capacitor is increased in order to lengthen the holding time, which tends to exacerbate the drawback that the control speed becomes slow.
問題点を解決するための手段
半導体レーザからの射出光の一部を検出する光検出回路
と、この光検出回路の出力値を基準電圧値と比較する比
較器と、この比較器の出力を追従して比較器出力値を保
持する保持回路と、前記半導体レーザに駆動電流を流す
第１電流源と、前記比較器からの出力と前記保持回路か
らの出力とを選択的に切換え再生時には前記比較器から
の直接出力値に応じて前記第１電流源を駆動させ記録及
び消去時には前記保持回路に保持された出力値に応じて
前記第１電流源を駆動させるスイッチ素子と、記録及び
消去時に駆動されて前記第１電流源による駆動電流に重
畳させて前記半導体レーザに駆動電流を流す第２電流源
とを設ける。Means for solving the problem: A photodetection circuit that detects a portion of the light emitted from the semiconductor laser, a comparator that compares the output value of this photodetection circuit with a reference voltage value, and a tracking device that tracks the output of this comparator. a holding circuit that holds the output value of the comparator; a first current source that supplies a drive current to the semiconductor laser; a switch element that drives the first current source according to a direct output value from the device and drives the first current source according to the output value held in the holding circuit during recording and erasing; and a second current source that causes a driving current to flow through the semiconductor laser superimposed on the driving current from the first current source.
作用
まず、再生時には、第１電流源のみが駆動されて半導体
レーザが発光するが、この時の発光パワーは光検出回路
により検出され、比較器により基準電圧と比較され、第
１電流源に連続的にフィードバックされて制御されるこ
とにより、半導体レーザの再生発光パワーが所定値に維
持される。この時、比較器出力が保持回路に保持される
が、再生パワー制御には関与しない。一方、記録時や消
去時には、第１電流源に対する制御が、比較器からの直
接出力値に代えて、スイッチ素子により保持回路を経る
制御系に切換えられ、保持回路に保持されている再生時
に保持した正確な比較出力値により第１電流源が駆動さ
れ、かつ、第２駆動源も重畳駆動され、半導体レーザは
記録又は消去に必要な発光パワーで発光する。First, during reproduction, only the first current source is driven and the semiconductor laser emits light, but the emitted light power at this time is detected by the photodetector circuit and compared with the reference voltage by the comparator, and the first current source is continuously The reproduction light emission power of the semiconductor laser is maintained at a predetermined value by being controlled by feedback. At this time, the comparator output is held in the holding circuit, but is not involved in reproduction power control. On the other hand, during recording or erasing, the control for the first current source is switched to a control system that passes through a holding circuit by a switch element, instead of using the direct output value from the comparator, and the value held in the holding circuit during playback is The first current source is driven by the accurate comparison output value, and the second drive source is also superimposedly driven, and the semiconductor laser emits light with the light emission power necessary for recording or erasing.
実施例 本発明の一実施例を図面に基づいて説明する。Example An embodiment of the present invention will be described based on the drawings.
まず、電源Ｖｃｃに接続された半導体レーザ１には再生
用定電流源（第１電流源）２と記録・消去用定電流源（
第２電流源）３とが並列・選択的に接続されている。ま
た、前記半導体レーザ１から射出された光の一部を受光
検出するフォトダイオード等の受光素子４が設けられ、
その受光量対応の電流は電流−電圧変換器５により電圧
信号とされる。これらの受光素子４と電流−電圧変換器
５とにより光検出回路６が構成されている。この光検出
回路６の電流−電圧変換器５からの検出電圧信号は比較
器７に入力され、基準電圧ＶＲＥＦ＋と比較される。こ
の比較器７からの比較出力が前記再生用定電流源２に与
えられ、受光素子４が受光した光量に応じてこの再生用
定電流源２から半導体レ−ザ１に流す駆動電流を調整す
ることにより、所望の再生パワーに制御される。First, a semiconductor laser 1 connected to a power supply Vcc includes a constant current source for reproduction (first current source) 2 and a constant current source for recording/erasing (
A second current source) 3 is selectively connected in parallel. Further, a light receiving element 4 such as a photodiode that receives and detects a part of the light emitted from the semiconductor laser 1 is provided,
The current corresponding to the amount of received light is converted into a voltage signal by the current-voltage converter 5. A photodetection circuit 6 is constituted by the light receiving element 4 and the current-voltage converter 5. The detected voltage signal from the current-voltage converter 5 of the photodetector circuit 6 is input to a comparator 7 and compared with a reference voltage VREF+. The comparison output from the comparator 7 is given to the regeneration constant current source 2, and the drive current flowing from the regeneration constant current source 2 to the semiconductor laser 1 is adjusted according to the amount of light received by the light receiving element 4. This allows the reproduction power to be controlled to a desired level.
また、変調可能な前記記録・消去用定電流源３に対して
は、記録時には基準電圧ＶＲＥＦ２を選択し、消去時に
は基準電圧Ｖ ＲＥＦ３を選択して駆動させるスイッチ
８が設けられている。Further, a switch 8 is provided for driving the modulated recording/erasing constant current source 3, which selects the reference voltage VREF2 during recording and selects the reference voltage VREF3 during erasing.
さらに、前記比較器７からの比較出力を常に追従して保
持する保持回路９が設けられている。ここに、木実流側
では前記再生用定電流源３に対し比較器７からの比較出
力値を直接出力する経路と、比較器７の比較出力値を保
持回路９に保持させて出力する経路とに２分されており
、これらの経路、即ち、比較器７からの出力と保持回路
９からの出力とを選択的に切換えるスイッチ素子１０が
設けられている。このスイッチ素子１０は再生時には比
較器７側を選択し、記録時及び消去時には保持回路９側
を選択するように切換え制御される。また、前記保持回
路９は再生時には比較器７の比較出力を常に追従する追
従モードにあり、記録時及び消去時には保持モードにあ
る。Furthermore, a holding circuit 9 is provided which always tracks and holds the comparison output from the comparator 7. Here, on the wood flow side, there is a path for directly outputting the comparison output value from the comparator 7 to the regeneration constant current source 3, and a path for holding the comparison output value of the comparator 7 in the holding circuit 9 and outputting it. A switch element 10 is provided to selectively switch these paths, that is, the output from the comparator 7 and the output from the holding circuit 9. This switch element 10 is controlled to select the side of the comparator 7 during reproduction, and select the side of the holding circuit 9 during recording and erasing. Further, the holding circuit 9 is in a tracking mode that always follows the comparison output of the comparator 7 during reproduction, and is in a holding mode during recording and erasing.
このような構成において、再生時にはスイッチ素子１０
は比較器７側を選択する切換え状態にあり、かつ、記録
・消去用定電流源３は駆動しない状態にある。これによ
り、前述したように、再生用定電流源２のみにより半導
体レーザ］を発光駆動させ、光検出回路４、比較器７、
再生用定電流源２による再生フィードバック制御系によ
る連続的な制御により、出射光量を再生用の一定パワー
に保つ。この時、保持回路９は再生制御系の動作に影響
を及ぼさないので、制御速度を落す必要がなく、高速か
つ高精度の再生パワー制御が可能となる。もつとも、保
持回路９は比較器７からの比較出力値を常に追従し保持
する動作をする。In such a configuration, during reproduction, the switch element 10
is in a switching state to select the comparator 7 side, and the recording/erasing constant current source 3 is not driven. As a result, as described above, the semiconductor laser is driven to emit light using only the reproduction constant current source 2, and the photodetector circuit 4, comparator 7,
Continuous control by the reproduction feedback control system using the constant current source 2 for reproduction keeps the amount of emitted light at a constant power for reproduction. At this time, since the holding circuit 9 does not affect the operation of the reproduction control system, there is no need to reduce the control speed, and high-speed and highly accurate reproduction power control is possible. However, the holding circuit 9 always follows and holds the comparison output value from the comparator 7.
一方、記録時にはスイッチ素子１０が比較器７側から保
持回路９側に切換えられ、再生時に比較器７からの比較
出力を保持していた保持回路９からの出力が有効となる
。これにより、今度は再生用定電流源２が保持回路９か
らの出力により制御されて半導体レーザ１に定電流を流
す。この時点では、保持回路９は保持モードにあり、比
較器７の出力値の変動の影響を受けない。また、記録・
消去用定電流源３も有効となるが、スイッチ８は基準電
圧ＶＲＥＦ２側が選択されてこの記録・消去用電流源３
が基準電圧ＶＲＥＦ２を基に記録信号により変調駆動し
、再生用定電流源による駆動電流に重畳されて半導体レ
ーザ１が駆動され、所望の記録パワーにて記録動作を行
う。On the other hand, during recording, the switch element 10 is switched from the comparator 7 side to the holding circuit 9 side, and during reproduction, the output from the holding circuit 9 that has held the comparison output from the comparator 7 becomes valid. As a result, the reproduction constant current source 2 is now controlled by the output from the holding circuit 9 and causes a constant current to flow through the semiconductor laser 1. At this point, the holding circuit 9 is in the holding mode and is not affected by fluctuations in the output value of the comparator 7. Also, records/
The constant current source 3 for erasing is also enabled, but the switch 8 is set to the reference voltage VREF2 side and this current source 3 for recording/erasing is activated.
is modulated and driven by a recording signal based on a reference voltage VREF2, and the semiconductor laser 1 is driven by being superimposed on a drive current from a constant current source for reproduction, thereby performing a recording operation with a desired recording power.
消去時も同様であり、再生用定電流源２と記録・消去用
定電流源３とによる重畳駆動電流により半導体レーザ１
が駆動される。この場合の再生用定電流源２の制御は記
録時と同じである。また、スイッチ８は基準電圧ＶＲＥ
Ｆ３を選択し、消去用の重畳電流を規制し、所定の消去
パワーが確保される。The same goes for erasing, and the semiconductor laser 1 is driven by the superimposed drive current from the reproduction constant current source 2 and the recording/erasing constant current source 3.
is driven. Control of the reproduction constant current source 2 in this case is the same as that during recording. Further, the switch 8 is connected to the reference voltage VRE.
F3 is selected, the superimposed current for erasing is regulated, and a predetermined erasing power is secured.
何れにしても、記録又は再生時には、再生時に保持回路
９により追従保持された高精度の比較器７の比較出力値
に基づき再生用定電流源２が制御されるので、記録・消
去用定電流源３による電流を重畳させるベースとなる再
生パワーを安定させることができ、よって、記録パワー
、消去パワーも安定したものとなる。In any case, during recording or playback, the constant current source 2 for playback is controlled based on the comparative output value of the high-precision comparator 7, which is tracked and held by the holding circuit 9 during playback. The reproducing power, which is the basis for superimposing the current from the source 3, can be stabilized, and therefore the recording power and erasing power can also be stabilized.
ところで、保持回路９は、具体的には例えば第２図（ａ
、）又は（ｂ）に示すように構成すればよい。By the way, specifically, the holding circuit 9 is shown in FIG.
, ) or (b).
まず、第２図（ａ）はＡ／Ｄ変換器１１とラッチ回路１
２とＤ／Ａ変換器１３とにより構成したものである。即
ち、再生時の比較器７からの比較出ノＪをＡ／Ｄ変換器
】１によりデジタル値に変換し、そのデジタル値をラッ
チ回路１２により保持する。First, FIG. 2(a) shows the A/D converter 11 and the latch circuit 1.
2 and a D/A converter 13. That is, the comparison output J from the comparator 7 during reproduction is converted into a digital value by the A/D converter 1, and the digital value is held by the latch circuit 12.
この動作は、再生時に、追従的に常時行われる。This operation is always performed in a follow-up manner during playback.
そして、記録時や消去時にはラッチ回路」２に制御信号
をケえてラッチしたデジタル値を出力させ、Ｄ／Ａ変換
器１３でアナログ信号に変換してスイブチ素子１０．Ｊ
生用定電流源２に出力させる。When recording or erasing, the latch circuit 2 outputs a latched digital value by passing a control signal, which is converted into an analog signal by the D/A converter 13 and sent to the switch element 10. J
The output is made to the constant current source 2 for raw use.
一方、第２図（ｂ）は比較器１４とアップダウンカウン
タ１５とＤ／Ａ変換器１６とにより保持回路９を構成し
た例を示す。まず、保持回路９の出力であるＤ／Ａ変換
器１６からの出力と、比較器７からの出力とを比較器１
４により比較する。比較の結果、保持回路９ （Ｄ／Ａ
変換器１６）からの出力のほうが大きい場合には、アッ
プダウンカンタ１５をカウントダウン動作させ、Ｄ／Ａ
変換器１６の出力を低下させる。一方、保持回路９がら
の出力のほうが小さい場合には、アップダウンカンタ１
５をアップダウン動作させ、Ｄ／Ａ変換器１６の出力を
大きくさせる。このようなり／Ａ変換器１６の出力の増
減により比較器７の出力を追従し、記録・消去時にはア
ップダウンカウンタ１５のアップ及びダウン動作を停止
させて保持モードとすることにより、その値を保持させ
るものである。On the other hand, FIG. 2(b) shows an example in which the holding circuit 9 is composed of a comparator 14, an up/down counter 15, and a D/A converter 16. First, the output from the D/A converter 16, which is the output of the holding circuit 9, and the output from the comparator 7 are connected to the comparator 1.
Compare by 4. As a result of the comparison, the holding circuit 9 (D/A
If the output from the converter 16) is larger, the up/down counter 15 is operated to count down, and the D/A
The output of converter 16 is reduced. On the other hand, if the output from the holding circuit 9 is smaller, the up-down counter 1
5 is operated up and down to increase the output of the D/A converter 16. In this way, the output of the comparator 7 is tracked by the increase/decrease in the output of the A converter 16, and when recording/erasing, the value is held by stopping the up and down operations of the up/down counter 15 and entering the holding mode. It is something that makes you
発明の効果
本発明は、上述したように構成したので、再生時には再
生制御系の動作に保持回路が関与しない状態とし、高速
かつ高精度な再生パワーの制御が可能となり、また、記
録時や消去時には再生１１６に保持回路に保持された比
較出力値を第１電流源の制御に用いているので安定した
再生パワーを確保した状態で必要なパワーを重畳させる
ことにより、記録パワー及び消去パワーを安定したもの
とすることができる。Effects of the Invention Since the present invention is configured as described above, the holding circuit is not involved in the operation of the playback control system during playback, making it possible to control the playback power at high speed and with high precision. Sometimes, the comparative output value held in the holding circuit is used in the reproduction 116 to control the first current source, so recording power and erasing power can be stabilized by superimposing the necessary power while ensuring stable reproduction power. It can be assumed that
図面は本発明の一実施例を示し、第１図は回路図、第２
図は保持回路の回路図である。
１・・・半導体レーザ、２・・・第１電流源、３・・・
第２電流源、６・・光検出回路、７・・・比較器、９・
・・保持回路、１０・・・スイッチ素子The drawings show one embodiment of the present invention, and FIG. 1 is a circuit diagram, and FIG. 2 is a circuit diagram.
The figure is a circuit diagram of a holding circuit. 1... Semiconductor laser, 2... First current source, 3...
2nd current source, 6... photo detection circuit, 7... comparator, 9...
・Holding circuit, 10 ・Switch element
Claims (1)
により光記録媒体上に集光照射し、情報の記録、再生又
は消去を行う光情報記録再生装置における半導体レーザ
制御回路において、前記半導体レーザからの射出光の一
部を検出する光検出回路と、この光検出回路の出力値を
基準電圧値と比較する比較器と、この比較器の出力を追
従して比較器出力値を保持する保持回路と、前記半導体
レーザに駆動電流を流す第１電流源と、前記比較器から
の出力と前記保持回路からの出力とを選択的に切換え再
生時には前記比較器からの直接出力値に応じて前記第１
電流源を駆動させ記録及び消去時には前記保持回路に保
持された出力値に応じて前記第１電流源を駆動させるス
イッチ素子と、記録及び消去時に駆動されて前記第１電
流源による駆動電流に重畳させて前記半導体レーザに駆
動電流を流す第２電流源とを設けたことを特徴とする半
導体レーザ制御回路。In a semiconductor laser control circuit in an optical information recording/reproducing apparatus that records, reproduces, or erases information by condensing and irradiating a laser beam emitted from a semiconductor laser onto an optical recording medium using an objective lens, the laser beam emitted from the semiconductor laser is a photodetection circuit that detects a part of the photodetection circuit; a comparator that compares the output value of the photodetection circuit with a reference voltage value; a holding circuit that tracks the output of the comparator and holds the comparator output value; a first current source that supplies a drive current to the semiconductor laser; and a first current source that selectively switches the output from the comparator and the output from the holding circuit according to the direct output value from the comparator during reproduction.
a switch element that drives a current source and drives the first current source according to an output value held in the holding circuit during recording and erasing; and a switch element that is driven during recording and erasing and superimposes on the drive current from the first current source. and a second current source for causing a drive current to flow through the semiconductor laser.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63126496A JPH01296439A (en) | 1988-05-24 | 1988-05-24 | Semiconductor laser control circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63126496A JPH01296439A (en) | 1988-05-24 | 1988-05-24 | Semiconductor laser control circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH01296439A true JPH01296439A (en) | 1989-11-29 |
Family
ID=14936646
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63126496A Pending JPH01296439A (en) | 1988-05-24 | 1988-05-24 | Semiconductor laser control circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH01296439A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100531559B1 (en) * | 1997-07-02 | 2006-03-28 | 소니 가부시끼 가이샤 | Information recording and reproducing apparatus and method |
-
1988
- 1988-05-24 JP JP63126496A patent/JPH01296439A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100531559B1 (en) * | 1997-07-02 | 2006-03-28 | 소니 가부시끼 가이샤 | Information recording and reproducing apparatus and method |
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