JPS61115250A - Optical disk reproducing device - Google Patents
Optical disk reproducing deviceInfo
- Publication number
- JPS61115250A JPS61115250A JP59235495A JP23549584A JPS61115250A JP S61115250 A JPS61115250 A JP S61115250A JP 59235495 A JP59235495 A JP 59235495A JP 23549584 A JP23549584 A JP 23549584A JP S61115250 A JPS61115250 A JP S61115250A
- Authority
- JP
- Japan
- Prior art keywords
- level
- signal
- reproduction signal
- disk
- reproduction
- 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
-
- 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
-
- 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
- G11B7/004—Recording, reproducing or erasing methods; Read, write or erase circuits therefor
- G11B7/005—Reproducing
Landscapes
- Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Optical Recording Or Reproduction (AREA)
Abstract
Description
【発明の詳細な説明】 産業上の利用分野 本発明は光学式ディスク再生装置に関する。[Detailed description of the invention] Industrial applications The present invention relates to an optical disc playback device.
従来の技術
ディスクを光学的に再生する装置においては、フォトダ
イオードよりの再生信号のレベルが変化すると、ＳＺＮ
比が変動したり、トラッキング及びフォーカスサーボ系
が正常に動作しなくなったりする悪影響が表われる。そ
こで、再生装置は、再生信号のレベルが一定に保たれる
ように構成しである。In a conventional device for optically reproducing a disc, when the level of the reproduction signal from the photodiode changes, the SZN
This results in adverse effects such as the ratio changing and the tracking and focus servo systems not operating properly. Therefore, the playback device is configured so that the level of the playback signal is kept constant.
第２図は従来の光学式ディスク再生装Ｎ１の１例を示す
。この再生装置ｔ１は、レーザビーム２を出射する半導
体３については、大略、レーザビームの光量が一定とな
るように制御し、４分割フォトダイオード４よりの再生
信号を操作してこのレベルが所定のレベルとなるように
制御する構成である。半導体３は、モニターダイオード
５と共にパッケージ６内に封入されている。半導体３は
、コリメートレンズ７側とモニターダイオード５側にレ
ーザビーム２を出射する。モニターダイオード５で光電
変換された信号は駆動電源８へ帰還されて、駆動電［８
よりの出力電圧を定める。これにより、半導体３は、出
射するレーザビーム２の光量が規定値に安定するように
制御される。FIG. 2 shows an example of a conventional optical disc reproducing device N1. The reproducing device t1 controls the semiconductor 3 that emits the laser beam 2 so that the light intensity of the laser beam is approximately constant, and controls the reproducing signal from the four-division photodiode 4 to maintain this level at a predetermined level. The configuration is such that control is performed to maintain the same level. The semiconductor 3 is enclosed in a package 6 together with a monitor diode 5. The semiconductor 3 emits the laser beam 2 to the collimator lens 7 side and the monitor diode 5 side. The signal photoelectrically converted by the monitor diode 5 is fed back to the drive power supply 8, and the drive power [8
Determine the output voltage. Thereby, the semiconductor 3 is controlled so that the amount of light of the emitted laser beam 2 is stabilized at a specified value.
光量が定まったレーザビーム２は、コリメートレンズ７
を通り、ハーフミラ−９で上方に反射され、対物レンズ
１０によりディスク１１の情報記録面１１ａに集光され
る。ディスク１１はモータ１２により高速で回転してい
る。レーザビーム２は、情報記録面１１ａで反射し、対
物レンズ１０゜ハーフミラ−９を透過し、レンズ１３に
より収束されて４分割フォトダイオード４を照射し、こ
）で光電変換され、各フォトダイオード素子４ａ〜４ｄ
より電気信号が出力される。全部の信号が加算器１４で
加算され、端子１５より再生信号として出力される。こ
）で、半導体３より出射されるレーザビーム２が所定光
量に制御されているので、ディスク１１で反射してフォ
トダイオード４へ入射する光量も安定し、各フォトダイ
オード素子４８〜４ｄよりの電気信号のレベルも安定し
、端子１５よりはレベルが安定した再生信号が出力され
ることになる。The laser beam 2 with a fixed amount of light is passed through the collimating lens 7
The light is reflected upward by the half mirror 9 and focused onto the information recording surface 11a of the disk 11 by the objective lens 10. The disk 11 is rotated at high speed by a motor 12. The laser beam 2 is reflected by the information recording surface 11a, passes through the objective lens 10° half mirror 9, is converged by the lens 13, and irradiates the 4-split photodiode 4, where it is photoelectrically converted, and each photodiode element 4a-4d
An electrical signal is output. All the signals are added by an adder 14 and outputted from a terminal 15 as a reproduced signal. In this case, since the laser beam 2 emitted from the semiconductor 3 is controlled to a predetermined amount of light, the amount of light reflected by the disk 11 and incident on the photodiode 4 is also stabilized, and the electricity from each photodiode element 48 to 4d is stabilized. The signal level is also stabilized, and a reproduced signal with a stable level is output from the terminal 15.
しかしながら、ディスク１１の汚れ具合又はディスク１
１の情報記録面１１ａ （反射ｗＡ）の性質により、デ
ィスク１１での反射率が同一ディスクのうちでも変化す
るような場合がある。このようなディスクを再生すると
きには、ディスクの影響を受けて再生中にフォトダイオ
ード４への入射光量が変動し、再生信号のレベルが変化
して、ＳＺＮ比が低下したり、サーボ回路の動作が不安
定となってしまう。However, if the dirt level of the disk 11 or the disk 1
Depending on the nature of the information recording surface 11a (reflection wA) of the disc 11, the reflectance of the disc 11 may vary even within the same disc. When playing back such a disk, the amount of light incident on the photodiode 4 changes during playback due to the influence of the disk, which changes the level of the playback signal, causing a decrease in the SZN ratio and the operation of the servo circuit. It becomes unstable.
これに対処するために、再生信号系に、自動利得調整回
路１６が設けである。この回路１６は、各フォトダイオ
ード素子４ａ〜４ｄに接続されている利得可変増幅器１
７ａ〜１７ｄと、各増幅器の出力側に接続しである信号
レベル検知器１８ａ〜１８ｄとよりなる。各信号レベル
検知器１８ａ〜１８ｄは入力する信号のレベルに対応し
た利得調整用の信号を発生し、これが対応する増幅器１
７ａ〜１７ｄに帰還されてこの利得を可変させる。これ
により、加算器１４へ出力される各再生信号のレベルは
成る規定値となり、端子１５からは、ディスク１１の状
況にも拘らず、レベルが安定した再生信号が出力される
。To cope with this, an automatic gain adjustment circuit 16 is provided in the reproduction signal system. This circuit 16 includes a variable gain amplifier 1 connected to each photodiode element 4a to 4d.
7a to 17d, and signal level detectors 18a to 18d connected to the output side of each amplifier. Each of the signal level detectors 18a to 18d generates a gain adjustment signal corresponding to the level of the input signal, and this signal is applied to the corresponding amplifier 1.
The gain is fed back to 7a to 17d to vary the gain. As a result, the level of each reproduced signal output to the adder 14 becomes a specified value, and a reproduced signal with a stable level is output from the terminal 15 regardless of the condition of the disk 11.
第３図は上記の自動利得調整回路１６の変形例を示す。FIG. 3 shows a modification of the automatic gain adjustment circuit 16 described above.
同図中、第２図に示す構成部分と対応する部分には同一
符号を付す。第３図の自動利得調整回路１９は、加算器
１４の次段に一つの信号レベル検知器２０を設けてなる
構成である。この信号レベル検知器２０からの利得調整
用信号により、各増幅器１７ａ〜１７ｄの利得が共通に
可変され、端子１５からはレベルが安定した再生信号が
出力される。In the figure, parts corresponding to those shown in FIG. 2 are given the same reference numerals. The automatic gain adjustment circuit 19 shown in FIG. 3 has a configuration in which one signal level detector 20 is provided at the next stage of the adder 14. The gains of the amplifiers 17a to 17d are commonly varied by the gain adjustment signal from the signal level detector 20, and a reproduced signal with a stable level is output from the terminal 15.
発明が解決しようとする問題点
上記の再生装置１においては、レベルが安定した再生信
号を得るために、光学系と再生信号系の両方を制御して
おり、構成が複雑となっていた。Problems to be Solved by the Invention In the reproducing apparatus 1 described above, both the optical system and the reproducing signal system are controlled in order to obtain a reproduced signal with a stable level, resulting in a complicated configuration.
再生信号系の制御についてみると、第２図の回路１６で
は、利得可変増幅器及び信号レベル検知器が各系統毎に
必要とされるため、第３図の回路１９に比べて構成が複
雑となる上に、各増幅器及び検知器の温度的特性及び時
間的特性が揃っている必要がある。第３図の回路１９で
は、信号レベル検知器が一つで足りる利点があるが、各
利得可変増幅器の特性を厳密に揃えなければならないと
いう、実際上は非常に困難な問題がある。Regarding the control of the reproduced signal system, the circuit 16 in FIG. 2 requires a variable gain amplifier and a signal level detector for each system, so the configuration is more complicated than the circuit 19 in FIG. 3. Additionally, the temperature and time characteristics of each amplifier and detector must be the same. Although the circuit 19 in FIG. 3 has the advantage that only one signal level detector is required, it has the problem that the characteristics of each variable gain amplifier must be precisely matched, which is very difficult in practice.
本発明は上記問題点を解決した光学式ディスク再生装置
を提供することを目的とする。An object of the present invention is to provide an optical disc playback device that solves the above problems.
問題点を解決するための手段
本発明は、ディスクよりの再生信号のレベルを検知し、
信号レベルが予め規定されたレベルとなるように、光ビ
ームの光量を制御するように構成したものである。Means for Solving the Problems The present invention detects the level of a playback signal from a disc,
The light intensity of the light beam is controlled so that the signal level becomes a predetermined level.
作用
再生信号系に自動利得調整回路を設けなくても、レベル
の安定した再生信号を得ることが出来、構成の簡略化が
図られる。Even without providing an automatic gain adjustment circuit in the operational reproduction signal system, a reproduced signal with a stable level can be obtained, and the configuration can be simplified.
実施例
第１図は本発明になる光学式ディスク再生装置２１の一
実施例を示す。同図中、第１図に示す構成部分と同一部
分には同一符号を付す。Embodiment FIG. 1 shows an embodiment of an optical disc reproducing apparatus 21 according to the present invention. In the figure, the same parts as those shown in FIG. 1 are given the same reference numerals.
半導体３より出射したレーザビーム２は、第２図と同じ
経路を経てディスク１１に到り、こ）で変調されて４分
割フォトダイオード４に到り、こ）で光電変換される。The laser beam 2 emitted from the semiconductor 3 reaches the disk 11 via the same path as shown in FIG. 2, is modulated by (a), and reaches the four-divided photodiode 4, where it is photoelectrically converted by (b).
各フォトダイオード素子４８〜４ｄよりの電気信号は、
加算器１４に加えられ、こ）で加算されて再生信号とさ
れて端子１５より出力される。The electrical signals from each photodiode element 48 to 4d are
The signals are added to the adder 14 and added thereto to form a reproduced signal, which is output from the terminal 15.
また、再生信号の一部は信号レベル検知器２２に加えら
れる。検知器２２は再生信号のレベルを検知して、レベ
ルに応じた制御信号を出力する。A portion of the reproduced signal is also applied to the signal level detector 22. The detector 22 detects the level of the reproduced signal and outputs a control signal according to the level.
この制御信号は駆動電源８に加えられ駆動電源８よりの
出力電圧を制御し、最終的には半導体３が出射するレー
ザビーム２の光量を可変させる。即ち、再生信号のレベ
ルが所定値より低下すると、駆動電源８よりの出力電圧
が上昇して、レーザビーム２の光量が増加し、逆に再生
信号のレベルが所定値より増加すると、駆動電源８より
の出力電圧が下降して、レーザビーム２の光量が減少す
る。This control signal is applied to the drive power supply 8 to control the output voltage from the drive power supply 8, and ultimately to vary the amount of light of the laser beam 2 emitted by the semiconductor 3. That is, when the level of the reproduced signal decreases below a predetermined value, the output voltage from the drive power supply 8 increases, and the amount of light of the laser beam 2 increases; The output voltage of the laser beam 2 decreases, and the amount of light of the laser beam 2 decreases.
これにより、ディスク１１に汚れ等があって反射率に差
があるような場合にも、各フォトダイオード素子４ａ〜
４ｄよりの電気信号に変化が生ぜず、再生信号のレベル
は所定の値に維持され、端子１５よりはレベルが安定し
た再生信号が出力される。As a result, even if there is a difference in reflectance due to dirt etc. on the disk 11, each photodiode element 4a to
There is no change in the electrical signal from terminal 4d, the level of the reproduced signal is maintained at a predetermined value, and a reproduced signal with a stable level is output from terminal 15.
従って、ディスク１１の状態に影響されずに、Ｓ／Ｎ比
は一定に保たれ、且つトラッキング及びフォーカスサー
ボ系も正常に動作する。Therefore, the S/N ratio is kept constant without being affected by the state of the disk 11, and the tracking and focus servo systems also operate normally.
なお、本実施例によれば、再生信号系には自動利得調整
回路は設けられていす、且つ信号レベル検出器２２も一
つであるため、回路構成は簡単であり、しかも自動利得
調整回路を構成する複数の利得可変増幅器の特性を揃え
るという必要も無い。According to this embodiment, since the reproduced signal system is not provided with an automatic gain adjustment circuit and there is only one signal level detector 22, the circuit configuration is simple, and the automatic gain adjustment circuit is not provided. There is no need to match the characteristics of the plurality of variable gain amplifiers.
発明の効果
上述の如く、本発明の光学式ディスク再生装置は、光源
より出射しディスクの情報記録面で反射した光ビームを
光電変換素子で受光し、該光電変換素子より再生信号を
得る光学式ディスク再生装置において、該再生信号のレ
ベルを検知する手段と、上記再生信号が予め規定された
レベルに保たれるように、該検知手段よりの出力に応じ
て該光源より出射される光ビームの光量を可変する手段
とを有してなる構成であるため、従来必要とされていた
再生信号系内の自動利得調整回路を省略することが出来
、然して構成の大幅な簡易化を図ることが出来、しかも
、ディスクの状態に影響されることなくレベルの安定し
た再生信号を得ることが出来るという特長を有する。Effects of the Invention As described above, the optical disc playback device of the present invention is an optical disc playback device that receives a light beam emitted from a light source and reflected on the information recording surface of the disc by a photoelectric conversion element, and obtains a playback signal from the photoelectric conversion element. The disc playback device includes means for detecting the level of the playback signal, and a means for controlling the light beam emitted from the light source according to the output from the detection means so that the playback signal is maintained at a predetermined level. Since the structure has a means for varying the amount of light, it is possible to omit the automatic gain adjustment circuit in the reproduction signal system that was conventionally required, and the structure can be greatly simplified. Moreover, it has the advantage of being able to obtain a reproduced signal with a stable level without being affected by the condition of the disc.
第１図は本発明の光学式ディスク再生装置の一実施例を
示す図、第２図は従来の光学式ディスク再生装置の１例
を示す図、第３図は第２図中自動利得調整回路の変形例
を示す図である。
２・・・レーザビーム、３・・・半導体、４・・・４分
割フォトダイオード、４８〜４ｄ・・・フォトダイオー
ド素子、８・・・駆動電源、１１・・・ディスク、１１
ａ・・・情報記録面、１４・・・加算器、２１・・・光
学式ディスク再生装置、２２・・・信号レベル検知器。FIG. 1 is a diagram showing an embodiment of the optical disc playback device of the present invention, FIG. 2 is a diagram showing an example of a conventional optical disc playback device, and FIG. 3 is the automatic gain adjustment circuit in FIG. 2. It is a figure showing a modification of . 2... Laser beam, 3... Semiconductor, 4... Quadrant photodiode, 48-4d... Photodiode element, 8... Drive power supply, 11... Disk, 11
a... Information recording surface, 14... Adder, 21... Optical disc playback device, 22... Signal level detector.
Claims (1)
ムを光電変換素子で受光し、該光電変換素子より再生信
号を得る光学式ディスク再生装置において、該再生信号
のレベルを検知する手段と、上記再生信号が予め規定さ
れたレベルに保たれるように、該検知手段よりの出力に
応じて該光源より出射される光ビームの光量を可変する
手段とを有してなることを特徴とする光学式ディスク再
生装置。In an optical disc playback device, a light beam emitted from a light source and reflected by an information recording surface of a disk is received by a photoelectric conversion element, and a playback signal is obtained from the photoelectric conversion element, and a means for detecting the level of the playback signal; and means for varying the amount of light beam emitted from the light source according to the output from the detection means so that the reproduced signal is maintained at a predetermined level. type disc playback device.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59235495A JPS61115250A (en) | 1984-11-08 | 1984-11-08 | Optical disk reproducing device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59235495A JPS61115250A (en) | 1984-11-08 | 1984-11-08 | Optical disk reproducing device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS61115250A true JPS61115250A (en) | 1986-06-02 |
Family
ID=16986879
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP59235495A Pending JPS61115250A (en) | 1984-11-08 | 1984-11-08 | Optical disk reproducing device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS61115250A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0411120A1 (en) * | 1987-04-15 | 1991-02-06 | Sony Corporation | Laser reproduction apparatus |
| JPH0529632U (en) * | 1991-09-30 | 1993-04-20 | 三菱自動車工業株式会社 | Automatic parts assembly machine |
| US5726961A (en) * | 1992-02-21 | 1998-03-10 | Pioneer Electronic Corporation | Optical pickup control system for optical discs having different reflectivities |
-
1984
- 1984-11-08 JP JP59235495A patent/JPS61115250A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0411120A1 (en) * | 1987-04-15 | 1991-02-06 | Sony Corporation | Laser reproduction apparatus |
| JPH0529632U (en) * | 1991-09-30 | 1993-04-20 | 三菱自動車工業株式会社 | Automatic parts assembly machine |
| US5726961A (en) * | 1992-02-21 | 1998-03-10 | Pioneer Electronic Corporation | Optical pickup control system for optical discs having different reflectivities |
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