JPS61279188A - Semiconductor laser driving apparatus - Google Patents
Semiconductor laser driving apparatusInfo
- Publication number
- JPS61279188A JPS61279188A JP60121850A JP12185085A JPS61279188A JP S61279188 A JPS61279188 A JP S61279188A JP 60121850 A JP60121850 A JP 60121850A JP 12185085 A JP12185085 A JP 12185085A JP S61279188 A JPS61279188 A JP S61279188A
- Authority
- JP
- Japan
- Prior art keywords
- semiconductor laser
- supplied
- drive
- driving
- voltage
- 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
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
Landscapes
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Optics & Photonics (AREA)
- Optical Head (AREA)
- Semiconductor Lasers (AREA)
Abstract
Description
【発明の詳細な説明】
［発明の技術分野］
本発明は、光学的情報記録再生装置、あるいは光学的に
情報を検知し伝達等する光学的情報処理装置に用いられ
る半導体レーザの駆動装置に関する。DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a driving device for a semiconductor laser used in an optical information recording/reproducing device or an optical information processing device that optically detects and transmits information.
［従来技術と問題点］
半導体レーザは小型、軽量、高効率である特徴から最近
、光学的情報記録再生装置（所謂光メモリ装置）やレー
ザプリンタなどに広く用いられている。しかし、半導体
レーザは駆動電圧の変動に敏感であり、また、逆耐圧が
小さく、過大な電圧の印加に対しても脆弱であるという
欠点を有している。このため、従来から各種の半導体レ
ーザ保護手段が提案されている（例えば特開昭５６−１
４４５９０号公報）。[Prior Art and Problems] Semiconductor lasers have recently been widely used in optical information recording and reproducing devices (so-called optical memory devices), laser printers, and the like because of their small size, light weight, and high efficiency. However, semiconductor lasers have the drawbacks of being sensitive to fluctuations in driving voltage, having a low reverse breakdown voltage, and being vulnerable to the application of excessive voltage. For this reason, various semiconductor laser protection means have been proposed (for example, JP-A-56-1
44590).
しかしながら、Ｌ記従来例によれば、電源がオンからオ
フあるいはオンに変わる変化を検出して該検出信号を遅
延させることにより、電源電圧が安定した後にこの遅延
信号にもとづいて半導体レーザな駆動するようにし、電
源投入時のスパイク電流が半導体レーザに流入しないよ
うにしたものであり、必ずしも誤り接続による逆電圧印
加に対して充分な保護をなしうる訳ではないという未解
決な問題点を有するものである。However, according to the conventional example L, by detecting a change in the power supply from on to off or on and delaying the detection signal, the semiconductor laser is driven based on this delayed signal after the power supply voltage is stabilized. This is to prevent spike current from flowing into the semiconductor laser when the power is turned on, and there is an unresolved problem that it does not necessarily provide sufficient protection against reverse voltage application due to incorrect connection. It is.
更に、゛最近の半導体レーザは高周波信号により変調さ
れてパルス状レーザ発振モードで使用される場合が多く
、レーザ光の出力安定化を行う光出力安定化回路（Ａｒ
ｃ）と、半導体レーザの駆動回路とは分離して設けられ
るものである。即ち、前記駆動回路は半導体レーザに近
接して配置され配線の短縮が図られ、一方、前記Ａｒｃ
は半導体レーザと隔った位置に配置され、各々はコネク
タ及びケーブル等により相互接続されて使用されるもの
である。このような場合には、半導体レーザに直結する
所謂最終段としての前記駆動回路に供給される電源電圧
の適正を監視する必要があり、前記従来技術によっては
１−記の如き場合に充分な半導体レーザの保護が図れな
いものである。Furthermore, recent semiconductor lasers are often modulated by high-frequency signals and used in pulsed laser oscillation mode, and an optical output stabilization circuit (Ar) is used to stabilize the output of laser light.
c) and the semiconductor laser drive circuit are provided separately. That is, the drive circuit is placed close to the semiconductor laser to shorten the wiring, while the Arc
are arranged at a position apart from the semiconductor laser, and are used by being interconnected by connectors, cables, etc. In such a case, it is necessary to monitor the appropriateness of the power supply voltage supplied to the drive circuit, which is the so-called final stage directly connected to the semiconductor laser. It is impossible to protect the laser.
［発明の１１的］
本発明は上記の如き従来技術の未解決の問題点を解消し
、半導体レーザを不適当な電気的駆動から防護する実用
性に優れた駆動装置を提供することを目的とする。[Eleventh aspect of the invention] It is an object of the present invention to solve the unresolved problems of the prior art as described above, and to provide a highly practical driving device that protects a semiconductor laser from inappropriate electrical driving. do.
［発明の概要］
本発明は−に起重的を達成するために、゛ト導体レーザ
の駆動装置において、半導体レーザを駆動する駆動回路
と、該駆動回路に供給される電源電圧が適正か否かを監
視して監視出力信号を発生する供給電圧監視手段と、前
記半導体レーザを駆動させるタイミングを指令する指令
信号と前記監視出力信号とを入力して適宜前記を導体レ
ーザの駆動を抑１トする半導体レーザ駆動抑止手段とを
備えて半導体レーザの駆動装置を構成し、前記半導体レ
ーザ駆動抑止手段は、前記駆動回路に供給される電圧が
適正な場合にのみ前記監視出力信号を受けて前記指令信
号に応じて半導体レーザを実際に駆動させレーザ光を出
力し、万一、不適当な電圧が前記駆動回路に供給された
場合（供給されるべき電圧が印加されない場合をも含む
）には前記半導体レーザ駆動抑１に手段は、前記指令信
号にもかかわらず半導体レーザに電気的入力を供給せず
半導体レーザの駆動を抑止して半導体レーザを破損、劣
化等から保護する作用をなすものである。[Summary of the Invention] In order to achieve the above-mentioned advantages, the present invention provides a drive circuit for driving a semiconductor laser and a power supply voltage supplied to the drive circuit in a drive device for a conductor laser. a supply voltage monitoring means that monitors the semiconductor laser and generates a monitoring output signal; inputs a command signal that instructs the timing to drive the semiconductor laser and the monitoring output signal, and suppresses the driving of the conductor laser as appropriate. and a semiconductor laser drive inhibiting means, wherein the semiconductor laser driving inhibiting means receives the monitoring output signal and executes the command only when the voltage supplied to the drive circuit is appropriate. The semiconductor laser is actually driven according to the signal to output laser light, and if an inappropriate voltage is supplied to the drive circuit (including a case where the voltage that should be supplied is not applied), the The means for suppressing the driving of the semiconductor laser 1 does not supply electrical input to the semiconductor laser despite the command signal and suppresses the driving of the semiconductor laser, thereby protecting the semiconductor laser from damage, deterioration, etc. .
［実施例］ 以ド、本発明を実施例にもとづいて詳細に説明する。[Example] Hereinafter, the present invention will be explained in detail based on examples.
第１図は本発明に係る半導体レーザ駆動装置を光学的情
報記録再生装置に組込んだ場合の実施例を示す要部の概
略構成図を示す。なお、以下の図面において同一作用を
なす同一部材には同一符号を付し、その説明を省略する
。１は半導体レーザの駆動回路１１、供給電圧監視手段
１２及び半導体レーザ駆動抑止手段１３を組込んだ半導
体レーザの駆動ユニットで、コネクタ２１及びケーブル
２２を介して電源供給回路３及びＡＰＣ回路４に接続さ
れている。５は光ピツクアップで内部に半導体レーザ（
図示されず）を有している。６は光ディスクでレーザ光
が照射され情報記録ｅＦｆ生又は消去される。FIG. 1 shows a schematic diagram of the main parts of an embodiment in which a semiconductor laser driving device according to the present invention is incorporated into an optical information recording/reproducing device. In the following drawings, the same members having the same function are given the same reference numerals, and the explanation thereof will be omitted. Reference numeral 1 denotes a semiconductor laser drive unit incorporating a semiconductor laser drive circuit 11, a supply voltage monitoring means 12, and a semiconductor laser drive inhibiting means 13, which is connected to a power supply circuit 3 and an APC circuit 4 via a connector 21 and a cable 22. has been done. 5 is an optical pickup with a semiconductor laser inside (
(not shown). Reference numeral 6 denotes an optical disk, which is irradiated with a laser beam to create or erase information recording eFf.
本実施例によれば、駆動回路１１は供給電圧監視手段１
２ 、 ゛ｉ導体レしザ駆動抑ＩＩ一手段１３とともに
半導体レーザの近傍に設けられた駆動ユニットｌに組込
まれ、高周波に変調された駆動パルスの半導体レーザへ
の伝送を容易にする。一方、電源供給回路３とＡＰＣ回
路４とは駆動ユニッ）１と分離され、コネクタ２１及び
ケーブル２２により接続されている。供給電圧監視手段
１２は駆動ユニットｌに供給される電圧の適否を監視し
監視出力信号を駆動抑止手段１３に入力する。しかして
、外部から駆動ユニット１に入力するレーザ発振指令信
号が半導体レーザの駆動を指令しても、例えばアクシデ
ントでコネクタ１３が離脱しているときには駆動ユニッ
トｌ内の供給電圧監視手段１２が異常を検知し監視出力
信号を駆動抑止手段１３に入力して半導体レーザの駆動
を抑止し、半導体レーザの異常状態下での駆動による劣
化や破壊から保護する作用をなすものである。According to this embodiment, the drive circuit 11 includes the supply voltage monitoring means 1
2. The i-conductor laser drive suppressor II is incorporated together with the means 13 into a drive unit l provided near the semiconductor laser, and facilitates transmission of drive pulses modulated at a high frequency to the semiconductor laser. On the other hand, the power supply circuit 3 and the APC circuit 4 are separated from the drive unit 1 and connected by a connector 21 and a cable 22. The supply voltage monitoring means 12 monitors the suitability of the voltage supplied to the drive unit l and inputs a monitoring output signal to the drive inhibiting means 13. Even if a laser oscillation command signal inputted to the drive unit 1 from the outside instructs the drive of the semiconductor laser, for example, if the connector 13 is disconnected due to an accident, the supply voltage monitoring means 12 in the drive unit 1 detects an abnormality. A detected and monitored output signal is input to the drive inhibiting means 13 to inhibit the driving of the semiconductor laser, thereby protecting the semiconductor laser from deterioration or destruction due to driving under abnormal conditions.
第２図に本発明の実施例である半導体レーザ駆動装置の
回路図を示す。７は半導体レーザである。８１は半導体
レーザ７を変調して発振させる変調入力信号、８２は供
給電圧で供給電圧監視手段１２に入力し監視された電圧
を駆動ユニット１の回路構成要素に供給する。８３はレ
ーザ駆動指令信号、８４は半導体レーザ７のバイアス電
流調整信し）、８５は半導体レーザ７のパルス変調され
た駆動電流の調整信号である。８６はアラーム信号で駆
動ユニント１から外部に異常を警報する。駆動回路１１
はドライブトランジスタ１１１゜１１４及び該ドライブ
トランジスタ１１１゜１１４に入力する変調入力信ｔ５
ｓｌのインバータ１１２、変調電流を供給する電流源１
１３から半導体レーザの変調駆動回路系を、また、バイ
アス電流供給電流源１１５によってバイアス電流駆動回
路系を構成する。半導体レーザの駆動抑止手段１３は供
給電圧監視手段１２の出力する監視出力信号１３１を人
力するトランジスタ１３２及び、レーザ駆動指令信号８
３を入力するトランジスタ１３３、前記トランジスタ１
３２，１３３に直列に接続するリレー１３４、該リレー
１３４により連動して開閉するスイッチ１３５及びそれ
らの周辺受動素子により構成される。なお、供給電圧監
視手段１２はツェナーダイオード、フォトカプラ、それ
に接続する論理回路等により構成されるものであり、１
２１は前記電流源１１３，１１５に所定の電圧（例えば
−１２ｖ）を供給するものである。 本実施例によれば
、その作用は次のとおりである。FIG. 2 shows a circuit diagram of a semiconductor laser driving device according to an embodiment of the present invention. 7 is a semiconductor laser. A modulation input signal 81 modulates the semiconductor laser 7 to cause it to oscillate, and a supply voltage 82 is input to the supply voltage monitoring means 12 to supply the monitored voltage to the circuit components of the drive unit 1. 83 is a laser drive command signal, 84 is a bias current adjustment signal for the semiconductor laser 7), and 85 is a pulse-modulated drive current adjustment signal for the semiconductor laser 7. 86 is an alarm signal that alerts the drive unit 1 to the outside of an abnormality. Drive circuit 11
is the drive transistor 111°114 and the modulation input signal t5 input to the drive transistor 111°114.
sl inverter 112, current source 1 supplying modulation current
13 constitutes a modulation drive circuit system for the semiconductor laser, and a bias current supply current source 115 constitutes a bias current drive circuit system. The semiconductor laser drive inhibiting means 13 includes a transistor 132 that manually outputs the monitoring output signal 131 output from the supply voltage monitoring means 12, and a laser drive command signal 8.
Transistor 133 inputting 3, said transistor 1
32 and 133, a switch 135 that opens and closes in conjunction with the relay 134, and peripheral passive elements thereof. The supply voltage monitoring means 12 is composed of a Zener diode, a photocoupler, a logic circuit connected thereto, etc.
Reference numeral 21 supplies a predetermined voltage (for example, -12V) to the current sources 113 and 115. According to this embodiment, the effects are as follows.
即ち、駆動ユニット１に供給される電圧８２（例えば電
流源１１３，１１５用の供給電圧１２１やインバータ１
１２を駆動せしめる為のバイアス電圧として（７）＋１
２Ｖ、−１２Ｖ、＋５Ｖ、−５Ｖ等）は供給電圧監視手
段１２に入力し、供給電圧が全て正常な場合Ｈレベルの
監視出力信号１３１をトランジスタ１３２に入力する。That is, the voltage 82 supplied to the drive unit 1 (for example, the supply voltage 121 for the current sources 113, 115 or the inverter 1
(7)+1 as a bias voltage to drive 12
2V, -12V, +5V, -5V, etc.) are input to the supply voltage monitoring means 12, and when all the supply voltages are normal, an H level monitoring output signal 131 is input to the transistor 132.
レーザ駆動指令信号８３はＨレベルの指令信号をトラン
ジスタ１３３に入力する。しかしてトランジスタ１３２
，１３３はＯＮとなりリレー１３４に電流を通じ連動す
るスイッチ１３５を切替えて半導体レーザ７の短絡を解
除する。ここでスイッチ１３５は通常半導体レーザ７を
短絡するように回路を選択して接続しており、半導体レ
ーザ７が静電気や、ノイズ等によって破損することを防
止するように作用しているものである。上記の如くスイ
ッチ１３５が切替り、半導体レーザの短絡が解除される
と外部からの変調入力信号８１に応じてインバータ１１
２及びトランジスタ１１１゜１１４を介して半導体レー
ザの駆動電流が電流源１１３．１１５から半導体レーザ
に流れ、所望のレーザ発光をさせる。他方、前記供給電
圧８２が不適正な場合には供給電圧監視手段１２はＬレ
ベルを出力するのでトランジスタ１３２はＯＦＦ状態で
あり、一方、外部からの駆動指令信号８３が入力した場
合にはトランジスタ１３３はＯＮ状態となる。その結果
リレー１３２には電流が流れずスイッチ１３５は半導体
レーザ７を短絡した状態を保持する。しかして、いかに
変調入力信号８１が入力してドライブトランジスタ１１
１，１１４が作動しても半導体レーザ７は短絡され電圧
印加されず、異常電圧下での駆動をまぬがれる作用をな
すものである。なお、このとき前記トランジスタ１３３
のＯＮに対応してアラーム信号はＬレベルとなり、異常
である旨を外部に報知するものである。The laser drive command signal 83 inputs an H level command signal to the transistor 133 . However, the transistor 132
, 133 are turned ON, current is passed through the relay 134, the interlocking switch 135 is switched, and the short circuit of the semiconductor laser 7 is released. Here, the switch 135 normally selects and connects a circuit to short-circuit the semiconductor laser 7, and serves to prevent the semiconductor laser 7 from being damaged by static electricity, noise, or the like. As described above, when the switch 135 is switched and the short circuit of the semiconductor laser is released, the inverter 11
A drive current for the semiconductor laser flows from current sources 113 and 115 to the semiconductor laser through transistors 111 and 114, causing the desired laser to emit light. On the other hand, when the supply voltage 82 is inappropriate, the supply voltage monitoring means 12 outputs the L level, so the transistor 132 is in the OFF state.On the other hand, when the drive command signal 83 from the outside is input, the transistor 133 is in the ON state. As a result, no current flows through the relay 132 and the switch 135 maintains the state in which the semiconductor laser 7 is shorted. Therefore, how can the modulation input signal 81 be input to the drive transistor 11?
Even if the semiconductor laser 1 and 114 are activated, the semiconductor laser 7 is short-circuited and no voltage is applied, thus preventing the semiconductor laser 7 from being driven under an abnormal voltage. Note that at this time, the transistor 133
In response to turning ON, the alarm signal goes to L level, which notifies the outside that there is an abnormality.
なお、上記実施例で供給電圧監視手段１２は前記の如く
供給電圧を入力するツェナーダイオドとそれに直列接続
する発光ダイオード、その光を光電変換する受光素子と
それに接続する比較器などの論理回路により構成するこ
とができるものである。In the above-mentioned embodiment, the supply voltage monitoring means 12 is composed of a logic circuit such as a Zener diode that inputs the supply voltage, a light emitting diode connected in series with the Zener diode, a light receiving element that photoelectrically converts the light, and a comparator connected thereto. It is something that can be configured.
［発明の効果１
本発明により半導体レーザは駆動回路に正常な電圧が供
給された場合にのみ駆動電圧が印加され、不適正な供給
電圧が駆動回路に供給された場合には半導体レーザに電
圧が印加されないので半導体レーザの異常電圧下での駆
動を防止することができ、半導体レーザの破損、劣化を
保護することができる効を奏するものである。[Effect of the invention 1] According to the present invention, a driving voltage is applied to the semiconductor laser only when a normal voltage is supplied to the driving circuit, and a voltage is applied to the semiconductor laser only when an inappropriate supply voltage is supplied to the driving circuit. Since no voltage is applied, it is possible to prevent the semiconductor laser from being driven under an abnormal voltage, which has the effect of protecting the semiconductor laser from damage and deterioration.
第１図は本発明を光学的情報記録再生装置に適用した場
合の要部構成図、第２図は半導体レーザ駆動装置の実施
例としての回路図である。
１・・・駆動ユニット
１、１・・・半導体レーザ駆動回路
１２・・・供給電圧監視手段
１３・・・半導体レーザ駆動抑止手段
３・・・電源供給Ｉｒ１ｌ路
４・・・ＡＰＣ
８３・・・半導体レーザ駆動指令信号
１３１・・・監視出力信号
第１図
１、駆動ユニット １１．駆動回路３、電源供
給回路 １２．供給電圧監視手段４、ＡＰＣ１
３，駆動抑止手段FIG. 1 is a block diagram of main parts when the present invention is applied to an optical information recording/reproducing device, and FIG. 2 is a circuit diagram as an embodiment of a semiconductor laser driving device. 1... Drive unit 1, 1... Semiconductor laser drive circuit 12... Supply voltage monitoring means 13... Semiconductor laser drive inhibiting means 3... Power supply Ir1l path 4... APC 83... Semiconductor laser drive command signal 131...monitoring output signal FIG. 1, drive unit 11. Drive circuit 3, power supply circuit 12. Supply voltage monitoring means 4, APC1
3. Drive suppression means
Claims (1)
を駆動する駆動回路と、該駆動回路に供給される電源電
圧が適正か否かを監視して監視出力信号を発生する供給
電圧監視手段 と、前記半導体レーザを駆動させるタイミングを指令す
る指令信号と前記監視出力信号とを入力して適宜前記半
導体レーザの駆動を抑止する半導体レーザ駆動抑止手段
とを備え、前記電源電圧が適正に供給されている場合に
のみ前記指令信号に応じて前記半導体レーザを駆動する
ことを特徴とする半導体レーザ駆動装置。(1) In a semiconductor laser driving device, a driving circuit that drives the semiconductor laser, a supply voltage monitoring means that monitors whether or not a power supply voltage supplied to the driving circuit is appropriate and generates a monitoring output signal; a semiconductor laser drive inhibiting means for appropriately inhibiting the driving of the semiconductor laser by inputting a command signal for instructing the timing to drive the semiconductor laser and the monitoring output signal, and when the power supply voltage is properly supplied; A semiconductor laser driving device characterized in that the semiconductor laser is driven only in accordance with the command signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60121850A JPS61279188A (en) | 1985-06-05 | 1985-06-05 | Semiconductor laser driving apparatus |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60121850A JPS61279188A (en) | 1985-06-05 | 1985-06-05 | Semiconductor laser driving apparatus |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS61279188A true JPS61279188A (en) | 1986-12-09 |
Family
ID=14821474
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP60121850A Pending JPS61279188A (en) | 1985-06-05 | 1985-06-05 | Semiconductor laser driving apparatus |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS61279188A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61289543A (en) * | 1985-06-17 | 1986-12-19 | Matsushita Electric Ind Co Ltd | Semiconductor laser driving circuit |
| JPS63160288A (en) * | 1986-12-24 | 1988-07-04 | Ricoh Co Ltd | Laser diode driving device |
| JPH0296936A (en) * | 1988-06-01 | 1990-04-09 | Canon Inc | Laser diode driving circuit |
| JP2007073841A (en) * | 2005-09-08 | 2007-03-22 | Sony Corp | Drive circuit |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS59147476A (en) * | 1983-02-10 | 1984-08-23 | Hitachi Koki Co Ltd | Protective device for semiconductor laser |
| JPS6182343A (en) * | 1984-09-29 | 1986-04-25 | Toshiba Corp | Automatic output adjusting circuit of laser diode |
-
1985
- 1985-06-05 JP JP60121850A patent/JPS61279188A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS59147476A (en) * | 1983-02-10 | 1984-08-23 | Hitachi Koki Co Ltd | Protective device for semiconductor laser |
| JPS6182343A (en) * | 1984-09-29 | 1986-04-25 | Toshiba Corp | Automatic output adjusting circuit of laser diode |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61289543A (en) * | 1985-06-17 | 1986-12-19 | Matsushita Electric Ind Co Ltd | Semiconductor laser driving circuit |
| JPS63160288A (en) * | 1986-12-24 | 1988-07-04 | Ricoh Co Ltd | Laser diode driving device |
| JPH0296936A (en) * | 1988-06-01 | 1990-04-09 | Canon Inc | Laser diode driving circuit |
| US5115147A (en) * | 1988-06-01 | 1992-05-19 | Canon Kabushiki Kaisha | Driver for light emitting device for providing a stable beam output |
| JP2007073841A (en) * | 2005-09-08 | 2007-03-22 | Sony Corp | Drive circuit |
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