JPS6278734A - Optical focus control device - Google Patents
Optical focus control deviceInfo
- Publication number
- JPS6278734A JPS6278734A JP21854385A JP21854385A JPS6278734A JP S6278734 A JPS6278734 A JP S6278734A JP 21854385 A JP21854385 A JP 21854385A JP 21854385 A JP21854385 A JP 21854385A JP S6278734 A JPS6278734 A JP S6278734A
- Authority
- JP
- Japan
- Prior art keywords
- objective lens
- optical
- light
- half mirror
- optical axis
- 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
Landscapes
- Automatic Focus Adjustment (AREA)
- Optical Recording Or Reproduction (AREA)
Abstract
Description
【発明の詳細な説明】
〔発明の利用分野〕
本発明は、光学焦点調整装置に係り、具体的にはビデオ
ディスク等の記録媒体上に記録された情報トラックに対
物レンズを介して光源から射出された光を集束させ、該
記録媒体からの反射光から記録された情報を読み取る装
置において、記録媒体に対する対物レンズの光学焦点調
整装置に関する。[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to an optical focus adjustment device, and specifically, the present invention relates to an optical focus adjustment device, and specifically, a method for emitting light from a light source through an objective lens onto an information track recorded on a recording medium such as a video disk. The present invention relates to an optical focusing device for an objective lens with respect to a recording medium in an apparatus for converging reflected light and reading recorded information from reflected light from the recording medium.
記録媒体、例えばビデオディスクにはその情報トランク
に符号化されたビデオ信号や音声信号が光学的情報とし
て記録されている。ビデオディスクに記録された情報は
、情報読取装置によりこれを高速で回転させなからレー
ザ光源から放射されるレーザ光を対物レンズを経て情報
トランク上に集束させ、情報トランクによって変調され
た透過光または反射光を検出して読み取っている。A recording medium, such as a video disk, has encoded video and audio signals recorded in its information trunk as optical information. The information recorded on the video disc is recorded on the video disc by rotating it at high speed using an information reading device, and then focusing the laser light emitted from the laser light source onto the information trunk through an objective lens. Detects and reads reflected light.
このような記録媒体では情報の記録密度が非常に高く、
この為に情報トランクの幅が極めて狭く、隣接する情報
トラック間のピッチも非常に狭くなっている。This type of recording medium has a very high information recording density,
For this reason, the width of the information trunk is extremely narrow, and the pitch between adjacent information tracks is also extremely narrow.
従って、このような情報トラックから記録情報を正確に
読み取る為には、対物レンズはビデオディスク面が常に
結像位置く合焦状態）となるようにしてディスク面上で
の光スポットの径を小さくする必要がある。この為に光
学的読取装置では対物レンズのディスク面での焦点外れ
を検出し、該検出信号に基づいて対物レンズをその光軸
方向に変位させて光学焦点の調整が行われる。Therefore, in order to accurately read recorded information from such information tracks, the objective lens must be kept in focus so that the video disc surface is always at the image formation position, thereby reducing the diameter of the light spot on the disc surface. There is a need to. For this purpose, the optical reading device detects defocusing of the objective lens on the disk surface, and adjusts the optical focus by displacing the objective lens in the direction of its optical axis based on the detection signal.
第３図には従来の光学的読取装置における光学焦点調整
方式を示しており、同図において、レーザ光源１００か
ら放射された光はコリメータレンズ１０２によって平行
光とされ、偏光膜を存する偏光プリズム１０４．１八波
長板１０６及び対物レンズ１０８を経て情報トラックを
含むディスク１１０上に集束される。この光束は凹凸の
ピット形状を持つ情報トラックにより反射され、対物レ
ンズ１０８およびＩ／、波長板１０６を経て偏光プリズ
ム１０４に入射する。偏光プリズム１０４に入射する反
射光は、′／４波長板１０６の作用により紙面に対し垂
直方向に偏光されているから、この光は偏光プリズム１
０４で反射される。この偏光プリズム１０４で反射され
た光束を集光レンズ１１２および円筒レンズ１１４によ
り集束させる。ここで円筒レンズ１１４は一軸方向にの
み集束作用を持つから、集光レンズ１１２および円筒レ
ンズ１１４による集束ビームの形状は、ディスク１１０
の位置が上下にずれると、情報トラックに正しく集束さ
れた状態（合焦位置）を境として直交した方向に変形す
る。形状変化は例えば四分割した光検出器（図示せず）
により検出して焦点調整信号を得、この信号によりフォ
ー力ッシング制御が行なわれてる。FIG. 3 shows an optical focus adjustment method in a conventional optical reading device. In the figure, light emitted from a laser light source 100 is made into parallel light by a collimator lens 102, and a polarizing prism 104 having a polarizing film is used. .1 eight-wavelength plate 106 and objective lens 108 onto a disk 110 containing information tracks. This light beam is reflected by an information track having a concavo-convex pit shape, and enters the polarizing prism 104 through the objective lens 108, the I/W plate 106, and the wavelength plate 106. Since the reflected light incident on the polarizing prism 104 is polarized in the direction perpendicular to the plane of the paper due to the action of the '/4 wavelength plate 106, this light is reflected by the polarizing prism 104.
It is reflected at 04. The light beam reflected by the polarizing prism 104 is focused by a condenser lens 112 and a cylindrical lens 114. Here, since the cylindrical lens 114 has a focusing effect only in one axis direction, the shape of the focused beam by the condenser lens 112 and the cylindrical lens 114 is
If the position of is shifted vertically, it will deform in a direction perpendicular to the state where it is correctly focused on the information track (focus position). For example, a photodetector divided into four parts (not shown) can change the shape.
Detection is performed to obtain a focus adjustment signal, and forcing control is performed using this signal.
このような従来の光学焦点調整方式にあっては、多数の
光学素子を必要とし、高価であるという欠点があった。Such conventional optical focus adjustment systems have the drawback of requiring a large number of optical elements and being expensive.
本発明は上記従来技術の欠点を解消し、簡単な構成で、
的確に対物レンズの光学焦点を調整することができる光
学焦点調整装置を提案することを目的としている。The present invention solves the drawbacks of the above-mentioned prior art, has a simple configuration, and
It is an object of the present invention to propose an optical focus adjustment device that can accurately adjust the optical focus of an objective lens.
本発明は、上記目的を達成するために、光源から射出さ
れた光を対物レンズを介して被照射物体表面に集束させ
且つ該反射光を受光検出器表面に集束させるようにした
光学系と、前記反射光を受光する受光検出器と、対物レ
ンズ若しくは被照射物体を前記光学系の光軸方向に移動
させる駆動手段と、前記受光検出器の検出信号を受けて
対物レンズが被照射物体に対して合焦状態になるまで対
物レンズ若しくは被照射物体４を前記光軸方向に移動さ
せるための制御信号を駆動手段に出力する制御手段とを
有し、前記光学系は、前記対物レンズと受光検出器との
間に光軸に対して所定角度傾斜させた状態で配設される
ハーフミラ−を含むことを特徴とするものである。In order to achieve the above object, the present invention includes an optical system that focuses light emitted from a light source onto the surface of an irradiated object via an objective lens, and focuses the reflected light onto the surface of a light receiving detector; a light receiving detector for receiving the reflected light; a driving means for moving the objective lens or the object to be irradiated in the optical axis direction of the optical system; and a control means for outputting a control signal to the driving means for moving the objective lens or the irradiated object 4 in the optical axis direction until it is in focus, and the optical system has a control means for outputting a control signal to the driving means for moving the objective lens or the irradiated object 4 in the optical axis direction until the object is in focus, and the optical system The device is characterized in that it includes a half mirror disposed between the mirror and the mirror at a predetermined angle with respect to the optical axis.
以下、添付図面に従って本発明に係る光学焦点調整装置
の好ましい実施例を詳説する。第１図には本発明に係る
光学焦点調整装置の一実施例の構成が示されている。同
図において、レーザ光源１０は例えば半導体レーザで構
成され、該レーザ光源１０の射出光は受光検出器１２と
対物レンズ１６との間に光軸６０に対して所定角度だけ
傾斜した状態で配設されたハーフミラ−１４により対物
レンズ１６側に方向転換され、ビデオディスク２０上の
情報トランクに集束されるように構成されている。DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an optical focus adjustment device according to the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 shows the configuration of an embodiment of an optical focus adjusting device according to the present invention. In the figure, a laser light source 10 is composed of, for example, a semiconductor laser, and the emitted light from the laser light source 10 is arranged between a light receiving detector 12 and an objective lens 16 at a predetermined angle with respect to an optical axis 60. The beam is deflected toward the objective lens 16 by the half mirror 14, and is focused onto the information trunk on the video disk 20.
また受光検出器１２はビデオディスク２０からの反射光
を対物レンズ１６、ハーフミラ−１４を介して受光し、
その検出信号を制御回路５０に出力する。制御回路５０
は受光検出器１２の検出信号に基づいて対物レンズ１６
の結像位置がビデオディスク２０表面にあるか否かを判
別し、ない場合には駆動装置３０に対し、対物レンズ１
６をディスク２０の表面が合焦位置となるように光軸６
０上で移動させるための制御信号を出力するように構成
されている。Further, the light receiving detector 12 receives reflected light from the video disc 20 via an objective lens 16 and a half mirror 14,
The detection signal is output to the control circuit 50. Control circuit 50
is the objective lens 16 based on the detection signal of the light receiving detector 12.
It is determined whether or not the imaging position of the objective lens 1 is on the surface of the video disc 20.
6 to the optical axis 6 so that the surface of the disc 20 is in focus.
It is configured to output a control signal for moving on 0.
上記構成からなる光学焦点調整装置の動作を以下に説明
する。レーザ光源１０からの射出光はハ−フミラー１４
により光軸６０に沿って反射され、該反射光は対物レン
ズ１６によりビデオディスク２０上の情報トラックに集
束される。そして情報トランクからの反射光は対物レン
ズ１６、ハーフミラ−１４を介して受光検出器１２の受
光面上に集束されるが、ハーフミラ−１４を通過する光
束の周縁における光線の光路長が互いに異なる為に受光
検出器１２における受光面上では点に結像すべき光束は
非点収差を生じ、その結像パターンは対物レンズ１６と
ビデオディスク２０との間の距離に応じて第２図に示す
ように変化する。第２図に示す結像パターンは光軸６０
に直交する平面上に形成される場合を示している。同図
において（Ｂ）は対物レンズ１６の焦点がビデオディス
ク２０上に存在する場合の結像パターンを示し、（Ａ）
はビデオディスク２０の上方（手前側）に焦点が存在す
る場合の結像パターンを、また（Ｃ）はビデオディスク
２０の下方（後側）に焦点が合っている場合の結像パタ
ーンを、それぞれ示している。The operation of the optical focus adjustment device having the above configuration will be explained below. The light emitted from the laser light source 10 passes through the half mirror 14.
along the optical axis 60, and the reflected light is focused by the objective lens 16 onto an information track on the video disc 20. The reflected light from the information trunk is focused on the light receiving surface of the light receiving detector 12 via the objective lens 16 and the half mirror 14, but since the optical path lengths of the light beams at the periphery of the light beam passing through the half mirror 14 are different from each other. The light beam that should be focused on a point on the light receiving surface of the light receiving detector 12 produces astigmatism, and the image forming pattern changes depending on the distance between the objective lens 16 and the video disk 20 as shown in FIG. Changes to The imaging pattern shown in Figure 2 is based on the optical axis 60.
The figure shows the case in which it is formed on a plane perpendicular to . In the figure, (B) shows an image formation pattern when the focus of the objective lens 16 is on the video disc 20, and (A)
(C) shows the image formation pattern when the focus is on the top (front side) of the video disc 20, and (C) shows the image formation pattern when the focus is on the bottom (back side) of the video disc 20. It shows.
受光検出器１２は上記結像パターンに応じた検出信号を
制御回路５０に出力する。制御回路５０は受光検出器１
２の検出出力に基づいて前記結像パターンを判別゛し、
その判別結果に基づいて対物レンズ１６を第２図（Ｂ）
の合焦状態になるまで光軸６０に沿って移動させるため
の制御信号を駆動装置３０に出力する。The light receiving detector 12 outputs a detection signal corresponding to the image formation pattern to the control circuit 50. The control circuit 50 is the light receiving detector 1
determining the imaging pattern based on the detection output of step 2;
Based on the determination result, the objective lens 16 is adjusted as shown in FIG. 2(B).
A control signal for moving the optical axis 60 along the optical axis 60 until the in-focus state is reached is output to the drive device 30.
受光検出器１２からの検出信号から前記結像パターンが
（Ｂ）になったことが制御回路５０により判定されると
、該制御回路５０は駆動装置３０を動作させる為の制御
信号の出力を停止する。When the control circuit 50 determines from the detection signal from the light receiving detector 12 that the image formation pattern becomes (B), the control circuit 50 stops outputting the control signal for operating the drive device 30. do.
このようにして対物レンズ１６がビデオディスク２０に
対し、合焦状態となるように対物レンズ１６とビデオデ
ィスク２０との間の距離が調節される。本実施例によれ
ば偏光プリズムの代りにハーフミラ−を用いることがで
き、また光学系を少数の光学素子で構成できるので装置
のコストを低減でき且つ製作が容易になる。In this way, the distance between the objective lens 16 and the video disc 20 is adjusted so that the objective lens 16 is in focus with respect to the video disc 20. According to this embodiment, a half mirror can be used instead of a polarizing prism, and the optical system can be constructed with a small number of optical elements, so the cost of the device can be reduced and manufacturing can be facilitated.
尚、本実施例では対物レンズ１６とビデオディスク２０
との間の距離を調節するのに対物レンズ１６を駆動装置
３０により光軸６０に沿って移動させるように構成した
が、これとは逆に対物レンズ１６を固定してビデオディ
スク２０側を光軸６０に沿って移動させるように構成し
てもよい。In this embodiment, the objective lens 16 and the video disc 20 are
The objective lens 16 was configured to be moved along the optical axis 60 by the driving device 30 to adjust the distance between It may be configured to move along the axis 60.
以上に説明したように本発明では光源から射出された光
を対物レンズを介して被照射物体表面に集束させ且つ該
反射光を受光検出器表面に集束させるように構成された
光学系において、前記対物レンズと受光検出器との間に
ハーフミラ−を光軸に対して所定角度だけ傾斜させた状
態で配設し、 。As explained above, in the present invention, in the optical system configured to focus the light emitted from the light source onto the surface of the irradiated object via the objective lens, and to focus the reflected light onto the surface of the light receiving detector, A half mirror is disposed between the objective lens and the light receiving detector, and is inclined at a predetermined angle with respect to the optical axis.
該ハーフミラ−の透過光により受光検出器の受光面上に
形成される結像パターンに基づいて対物レンズと被照射
物体表面との距離を調節することにより対物レンズの光
学焦点を調整するように構成したので光学系を少数の光
学素子で構成することができ、簡単な構成で且つ的確に
光学焦点を調整することができる。The optical focus of the objective lens is adjusted by adjusting the distance between the objective lens and the surface of the object to be irradiated based on the image formation pattern formed on the light receiving surface of the light receiving detector by the transmitted light of the half mirror. Therefore, the optical system can be configured with a small number of optical elements, and the optical focus can be adjusted accurately with a simple configuration.
また、本発明によれば簡単な構成にすることができるの
で安価な光学焦点調整装置を実現できるFurther, according to the present invention, since the configuration can be simplified, an inexpensive optical focus adjustment device can be realized.
第１図は本発明に係る光学焦点調整装置の一実施例を示
す構成図、第２図は第１図における受光検出器１２の受
光面における結像パターンを示す説明図、第３図は従来
の光学的読取装置の要部を示す構成図である。
１０・・・レーザ光源、 １２・・・受光検出器、 １
４・・・ハーフミラ−１１６・・・対物レンズ、２゜・
・・ビデオディスク、 ３０・・・駆動装置、 ５ｏ
・・・制御回路。FIG. 1 is a configuration diagram showing an embodiment of an optical focus adjustment device according to the present invention, FIG. 2 is an explanatory diagram showing an image formation pattern on the light receiving surface of the light receiving detector 12 in FIG. 1, and FIG. 3 is a conventional diagram. 1 is a configuration diagram showing main parts of an optical reading device of FIG. 10... Laser light source, 12... Light receiving detector, 1
4... Half mirror 116... Objective lens, 2°.
...Video disc, 30...Drive device, 5o
...Control circuit.
Claims (1)
表面に集束させ且つ該被照射物体からの反射光を受光検
出器表面に集束させるようにした光学系と、前記反射光
を受光する受光検出器と、対物レンズ若しくは被照射物
体を前記光学系の光軸方向に移動させる駆動手段と、前
記受光検出器の検出信号を受けて対物レンズが被照射物
体に対して合焦状態になるまで対物レンズ若しくは被照
射物体を前記光軸方向に移動させるための制御信号を騒
動手段に出力する制御手段とを有し、前記光学系は、前
記対物レンズと受光検出器との間に光軸に対して所定角
度傾斜させた状態で配設されるハーフミラーを含むこと
を特徴とする光学焦点調整装置。an optical system that focuses light emitted from a light source onto the surface of an irradiated object via an objective lens and focuses reflected light from the irradiated object on the surface of a light receiving detector; and a light receiver that receives the reflected light. a detector, a drive means for moving an objective lens or an object to be irradiated in the optical axis direction of the optical system, and a drive means for moving an objective lens or an object to be irradiated in the optical axis direction of the optical system, until the objective lens is brought into focus on the object to be irradiated in response to a detection signal from the light receiving detector. and a control means for outputting a control signal to the disturbance means for moving the objective lens or the irradiated object in the optical axis direction, and the optical system is arranged between the objective lens and the light receiving detector along the optical axis. An optical focus adjustment device comprising a half mirror arranged at a predetermined angle with respect to the half mirror.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP21854385A JPS6278734A (en) | 1985-10-01 | 1985-10-01 | Optical focus control device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP21854385A JPS6278734A (en) | 1985-10-01 | 1985-10-01 | Optical focus control device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS6278734A true JPS6278734A (en) | 1987-04-11 |
Family
ID=16721577
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP21854385A Pending JPS6278734A (en) | 1985-10-01 | 1985-10-01 | Optical focus control device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6278734A (en) |
-
1985
- 1985-10-01 JP JP21854385A patent/JPS6278734A/en active Pending
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