JPH02223023A - Focus leading-in device - Google Patents
Focus leading-in deviceInfo
- Publication number
- JPH02223023A JPH02223023A JP4374789A JP4374789A JPH02223023A JP H02223023 A JPH02223023 A JP H02223023A JP 4374789 A JP4374789 A JP 4374789A JP 4374789 A JP4374789 A JP 4374789A JP H02223023 A JPH02223023 A JP H02223023A
- Authority
- JP
- Japan
- Prior art keywords
- objective lens
- focus
- servo circuit
- detection signal
- leading
- 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
- 238000001514 detection method Methods 0.000 claims abstract description 11
- 230000003287 optical effect Effects 0.000 description 18
- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 230000001133 acceleration Effects 0.000 description 1
Abstract
Description
【発明の詳細な説明】
産業上の利用分野
本発明は光ディスクなどの光学ピックアップの焦点引き
込み装置に関するものである。DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a focus pulling device for an optical pickup such as an optical disc.
従来の技術
光学ピックアップは光源からの光を対物レンズで集光し
その対物レンズをアクチュエータにより動かし光ビーム
を光デイスク上に結像させるのであるが、焦点を結像さ
せるためには初期に対物レンズを移動して焦点位置を捜
す引き込み動作が必要となる。以下、この引き込み動作
について従来例を基に説明する。第３図に光学ピックア
ップの構図を示すが、半導体レーザからなる光源５の光
は対物レンズ２により光デイスク１上に結像されるが光
ディスク１からの反射光はハーフミラ−４により分光さ
れ検出器６に入射する。この検出器６は対物レンズ２と
光ディスク１との距離により光量が変わる焦点検出のた
めの検出器であり、この出力はサーボ回路７に入力され
、適正焦点位置を自動的に保つようにアクチュエータ３
を駆動する。この光学ピックアップを動作させる初期に
は対物レンズ２は光ディスク１から離れているため、焦
点を引き込むための初期動作が必要であるが、三角波発
生回路８により三角波を発生し、対物レンズ２を光ディ
スク１に近付けていき、適正な位置をコンパレータ９で
検出し、スイッチ１０でサーボ回路７と切り換え、引き
込み動作を完了する。Conventional optical pickups use an objective lens to collect light from a light source, and move the objective lens using an actuator to form an image of the light beam on an optical disk. A pull-in operation is required to move the lens and search for the focal position. This pull-in operation will be explained below based on a conventional example. FIG. 3 shows the composition of an optical pickup. Light from a light source 5 consisting of a semiconductor laser is imaged onto an optical disk 1 by an objective lens 2, but the reflected light from the optical disk 1 is separated by a half mirror 4 and sent to a detector. 6. This detector 6 is a detector for focus detection where the amount of light changes depending on the distance between the objective lens 2 and the optical disk 1. This output is input to a servo circuit 7, and the actuator 3 is used to automatically maintain a proper focus position.
to drive. At the beginning of operating this optical pickup, the objective lens 2 is far from the optical disc 1, so an initial operation is necessary to pull in the focus. The comparator 9 detects the proper position, and the switch 10 switches to the servo circuit 7 to complete the pulling operation.
発明が解決しようとする課題
上記構成において、対物レンズ２は適正位置の検知によ
りサーボ回路７に切り替わり引き込まれるが、引き込む
タイミングによっては、サーボ回路７に切り替わった瞬
時に加速度を持ち、サーボ範囲を越えてしまって、引き
込まれなくなる場合が生じるという課題がある。Problems to be Solved by the Invention In the above configuration, the objective lens 2 is switched to the servo circuit 7 and pulled in when the proper position is detected, but depending on the timing of the pull-in, it has an acceleration at the instant it switches to the servo circuit 7, and may exceed the servo range. There is a problem that there are cases where the user is unable to be drawn in because of the situation.
そこで、本発明では、上記課題を解決するための焦点引
き込み装置を提案する。Therefore, the present invention proposes a focus pulling device for solving the above problems.
課題を解決するための手段
上記課題を解決するために本発明は、サーボ回路の焦点
を引き込むタイミングを焦点検出信号のピーク付近とす
る構成としたものである。Means for Solving the Problems In order to solve the above problems, the present invention has a configuration in which the timing for drawing the focus of the servo circuit is near the peak of the focus detection signal.
作用
上記のように焦点の引き込みタイミングを焦点検出信号
のピーク付近とすることにより、引き込み時に対物レン
ズが持っている移動速度を打ち消す方向にサーボ信号が
発生し、対物レンズが必要以上に移動せず、安定に焦点
位置へと移動し引き込み動作が確実となるのである。Effect As mentioned above, by setting the focus retraction timing near the peak of the focus detection signal, a servo signal is generated in the direction that cancels the movement speed of the objective lens at the time of retraction, and the objective lens does not move more than necessary. , it moves stably to the focal position and the retraction operation becomes reliable.
実施例
本発明の詳細を図を用いて説明する。第１図に本発明の
焦点引き込み装置を示している。第１図において１１は
光ディスク、１２は対物レンズでアクチュエータ１３に
よって移動する。１４はノ＼−フミラーで、半導体レー
ザよりなる光源１５からの光を対物レンズ１２を通じて
光デイスク１１上に結像させ、この光ディスク１１から
の反射光を分光させて焦点検出器１６に入射させるもの
である。この焦点検出器１６の出力はサーボ回路１７に
入力され、適正焦点位置を自動的に保つようにアクチュ
エータ１３を駆動し対物レンズ１２を移動させる。１８
は光ディスク１１から離れている対物レンズ１２を光デ
ィスク１１に近付（ように駆動させる初期動作を発生さ
せる三角波を得るための三角波発生回路で、対物レンズ
１２を光ディスク１１に近付けて適正な位置をコンパレ
ータ１９で検出し、スイッチ２０でサーボ回路１７と切
り換え、引き込み動作を行なうように構成されている。EXAMPLE The details of the present invention will be explained with reference to the drawings. FIG. 1 shows a focus pulling device of the present invention. In FIG. 1, 11 is an optical disk, and 12 is an objective lens, which is moved by an actuator 13. Reference numeral 14 denotes a nof mirror which forms an image of light from a light source 15 made of a semiconductor laser on the optical disk 11 through an objective lens 12, separates the reflected light from the optical disk 11, and makes it incident on a focus detector 16. It is. The output of the focus detector 16 is input to a servo circuit 17, which drives the actuator 13 to move the objective lens 12 so as to automatically maintain a proper focus position. 18
is a triangular wave generation circuit for generating a triangular wave that generates an initial operation for driving the objective lens 12, which is away from the optical disc 11, close to the optical disc 11. 19, the switch 20 switches to the servo circuit 17, and a pull-in operation is performed.
第２図は焦点検出信号を示すが、図の横軸方向が対物レ
ンズ１２の移動距離を表し、縦軸が焦点検出信号を表す
。この時、焦点引き込みの初期に三角波発生回路１８で
アクチュエータ１３を駆動することにより対物レンズ１
２は図の横軸方向に移動し、焦点検出信号がＯとなる点
が焦点が合ったことを示す。したがって、図の下の（ａ
）に示すタイミングでサーボ回路１７をオンすることに
より対物レンズ１２は焦点位置に引き込まれ、以後サー
ボ回路１７により自動的に焦点位置を保つのである。と
ころが、この場合、（ａ）のタイミングで引き込むと、
この時点では対物レンズ１２は三角波発生回路１８の駆
動による速度を保持しているためサーボ回路１７をオン
してもある程度対物レンズ１２は移動してしまい、極端
な場合にはサーボ回路１７がはずれてしまうのである。FIG. 2 shows a focus detection signal, where the horizontal axis of the figure represents the moving distance of the objective lens 12, and the vertical axis represents the focus detection signal. At this time, by driving the actuator 13 with the triangular wave generating circuit 18 at the initial stage of focusing, the objective lens 1
The point 2 moves in the horizontal axis direction of the figure, and the point where the focus detection signal becomes O indicates that the point is in focus. Therefore, (a
) By turning on the servo circuit 17, the objective lens 12 is drawn into the focal position, and thereafter the servo circuit 17 automatically maintains the focal position. However, in this case, if you pull in at timing (a),
At this point, the objective lens 12 maintains the speed driven by the triangular wave generation circuit 18, so even if the servo circuit 17 is turned on, the objective lens 12 will move to some extent, and in extreme cases, the servo circuit 17 may become disconnected. It's put away.
そこで、サーボ回路１７をオンとするタイミングを図の
（ｂ）のように、焦点検出信号のピークとすることによ
り、この瞬間には対物レンズ１２は適正焦点位置にない
ためサーボ信号はアクチュエータ１３に対して信号を発
生し、これが、その時点で対物レンズがもっている三角
波発生回路１８の駆動による速度を打ち消し、対物レン
ズ１２はスムーズに焦点位置に引き込まれるのである。Therefore, by setting the timing at which the servo circuit 17 is turned on to the peak of the focus detection signal as shown in (b) in the figure, the servo signal is sent to the actuator 13 because the objective lens 12 is not at the proper focus position at this moment. In response to this, a signal is generated, which cancels out the speed driven by the triangular wave generation circuit 18 that the objective lens has at that time, and the objective lens 12 is smoothly drawn into the focal position.
発明の効果
以上にように本発明による焦点引き込み装置では、簡単
な構成でより安定した引き込みが実現できるのである。Effects of the Invention As described above, the focus pulling device according to the present invention can achieve more stable focusing with a simple configuration.
また本発明は光ディスクのみでなく、光磁気ディスクに
も有効であることは明らかである−０Furthermore, it is clear that the present invention is effective not only for optical disks but also for magneto-optical disks.
第１図は本発明の焦点引き込み装置の一実施例を示す概
略構成図、第２図は焦点検出信号、（ａ）は従来例によ
る引き込みタイミング、（ｂ）は本発明による引き込み
タイミングを示す。第３図はディスクの光学ピックアッ
プの一般的な構成例を示す概略構成図である。
１１・・・・・・光ディスク、１２・・・・・・対物レ
ンズ、１３・・・・・・レンズ駆動のためのアクチュエ
ータ、１４・・・・・・ハーフミラ−１５・・・・・・
光源、１６・・・・・・焦点検出器、１７・・・・・・
サーボ回路、１８・・・・・・三角波発生回路、１９・
・・・・・コンパレータ、２０・・・・・・切り換えス
イッチ。FIG. 1 is a schematic configuration diagram showing an embodiment of the focus pull-in device of the present invention, FIG. 2 is a focus detection signal, (a) shows the pull-in timing according to a conventional example, and (b) shows the pull-in timing according to the present invention. FIG. 3 is a schematic configuration diagram showing a general configuration example of an optical pickup for a disc. 11... Optical disk, 12... Objective lens, 13... Actuator for driving the lens, 14... Half mirror 15...
Light source, 16... Focus detector, 17...
Servo circuit, 18... Triangular wave generation circuit, 19.
... Comparator, 20 ... Changeover switch.
Claims (1)
らの光の焦点を合わせるための対物レンズと、この対物
レンズの駆動手段と、焦点を自動的に合わせるためのサ
ーボ回路よりなり、このサーボ回路を、焦点検出信号の
ピーク部分で作動させることを特徴とする焦点引き込み
装置。It consists of a focus detector that detects the focal position on the disk, an objective lens that focuses the light from the light source, a drive means for this objective lens, and a servo circuit that automatically adjusts the focus. A focus pulling device characterized in that a circuit is operated at a peak portion of a focus detection signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4374789A JPH02223023A (en) | 1989-02-23 | 1989-02-23 | Focus leading-in device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4374789A JPH02223023A (en) | 1989-02-23 | 1989-02-23 | Focus leading-in device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH02223023A true JPH02223023A (en) | 1990-09-05 |
Family
ID=12672355
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4374789A Pending JPH02223023A (en) | 1989-02-23 | 1989-02-23 | Focus leading-in device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH02223023A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005129089A (en) * | 2000-03-03 | 2005-05-19 | Sony Computer Entertainment Inc | Focus control unit, recording medium, and optical disk reproducing device |
| US7151722B2 (en) * | 2000-10-25 | 2006-12-19 | Hitachi, Ltd. | Optical disc apparatus switching focus point between layers |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63244321A (en) * | 1987-03-30 | 1988-10-11 | Matsushita Electric Ind Co Ltd | Automatic focus draw-in adjusting device |
-
1989
- 1989-02-23 JP JP4374789A patent/JPH02223023A/en active Pending
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63244321A (en) * | 1987-03-30 | 1988-10-11 | Matsushita Electric Ind Co Ltd | Automatic focus draw-in adjusting device |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005129089A (en) * | 2000-03-03 | 2005-05-19 | Sony Computer Entertainment Inc | Focus control unit, recording medium, and optical disk reproducing device |
| US7151722B2 (en) * | 2000-10-25 | 2006-12-19 | Hitachi, Ltd. | Optical disc apparatus switching focus point between layers |
| US7200075B2 (en) | 2000-10-25 | 2007-04-03 | Hitachi, Ltd. | Optical disc apparatus switching focus point between layers |
| US7212472B2 (en) | 2000-10-25 | 2007-05-01 | Hitachi, Ltd. | Focus point switching |
| US7471597B2 (en) | 2000-10-25 | 2008-12-30 | Hitachi, Ltd. | Optical disc apparatus switching focus point between layers |
| US7848190B2 (en) | 2000-10-25 | 2010-12-07 | Hitachi, Ltd. | Optical disc apparatus switching focus point between layers |
| US8284644B2 (en) | 2000-10-25 | 2012-10-09 | Hitachi, Ltd. | Optical disc apparatus switching focus point between layers |
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