JPS619845A - Optical pickup device - Google Patents
Optical pickup deviceInfo
- Publication number
- JPS619845A JPS619845A JP59129658A JP12965884A JPS619845A JP S619845 A JPS619845 A JP S619845A JP 59129658 A JP59129658 A JP 59129658A JP 12965884 A JP12965884 A JP 12965884A JP S619845 A JPS619845 A JP S619845A
- Authority
- JP
- Japan
- Prior art keywords
- light
- face
- half prism
- reflected
- irregular reflection
- 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
- G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
Landscapes
- Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Optical Head (AREA)
Abstract
Description
【発明の詳細な説明】
イ、産業上の利用分野
本発明は光学式ビデオディスクプレーヤ、光学式デジタ
ルオーディオディスクプレーヤ等に利用し得る光学式ピ
ックアップ装置に関する。DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to an optical pickup device that can be used in optical video disc players, optical digital audio disc players, and the like.
口、従来技術
第１図は一般的な光学式ピックアップ装置を示す図であ
る。図に於いて（１）は半導体レーザ、（２）は回折格
子、（３）はハーフプリズム−１（４１は対物レンズ、
（５）は凹レンズ、（６１はシリンドリカルレンズ、＋
７１は７オトセンサである。この例は、トラッキング制
御方式がいわゆる６ビ一ム方式となっておシ、一対のト
ラッキング用センサ（７Ｂ）（７ｂ）によりトラッキン
グエラーが検出される。また、フォーカス制御方式はい
わゆる非点収差方式となっておシ、４分割フォトセンサ
（７Ｃ）により、フォーカスエラーが検出される。もち
ろん情報（ＲＦ）信号も４分割フォトセンサ（７Ｃ）よ
り検出される。1. Prior Art FIG. 1 is a diagram showing a general optical pickup device. In the figure, (1) is a semiconductor laser, (2) is a diffraction grating, (3) is a half prism-1 (41 is an objective lens,
(5) is a concave lens, (61 is a cylindrical lens, +
71 is a 7 oto sensor. In this example, the tracking control method is a so-called 6-beam method, and a tracking error is detected by a pair of tracking sensors (7B) (7b). Further, the focus control method is a so-called astigmatism method, and a focus error is detected by a 4-split photosensor (7C). Of course, the information (RF) signal is also detected by the 4-split photosensor (7C).
半導体レーザ（１）から出射され＊０．７６μｍ〜０゜
８２μｍの波長を持つレーザビームは回折格子（２）に
て６ビームに分けられ、ハーフプリズム（３）に入射さ
れる。入射された光ビームの略半分がハーフプリズム（
３）を透過し、対物レンズ（４）に入射される。A laser beam emitted from a semiconductor laser (1) and having a wavelength of *0.76 μm to 0°82 μm is divided into six beams by a diffraction grating (2) and is incident on a half prism (3). Approximately half of the incident light beam passes through the half prism (
3) and enters the objective lens (4).
対物レンズ（４）にてビームは絞られディスク（８）の
記碌面でれ直径約１，２μｍとなる。ディスク（８）に
照射された光ビームは、ディスクに設けられたピット（
凹部）により回折を受け、ディスク（８）よ”り反射さ
れる光ビームは記録されたピット（情報）に応じて強弱
に変調される。即ち、反射ビームは情報を含んだものと
なっている。この反射ビームは、対物レンズ（４）を通
過し、ハーフプリズム（３）に入射される。そして、入
射されたうちの約半分のビームが凹レンズ（５） 、シ
リンドリカルレンズ（６）を通過してフォトセンサ（７
）に入射される。The beam is focused by the objective lens (4) and has a diameter of about 1.2 μm on the recording surface of the disk (8). The light beam irradiated onto the disk (8) hits the pit (
The light beam that is diffracted by the recesses) and reflected from the disk (8) is modulated in intensity depending on the recorded pits (information).In other words, the reflected beam contains information. This reflected beam passes through the objective lens (4) and enters the half prism (3).About half of the incident beam passes through the concave lens (5) and the cylindrical lens (6). photo sensor (7
).
さて、上述した従来のピックアップ装置に於いては、次
の如き問題を有していた。即ち、トラッキングエラー信
号若しくはＲＦ倍信号、比較的低周波の光の相互干渉に
よるノイズが発生し易いことである。第５図はノイズの
発生原因の一つであるハーフプリズム（３）とそれを通
るレーザビーム光の干渉作用を示している。図に於いて
、入射光（Ａ）はハーフプリズム（３）に依シ、その約
半分が透過光（Ｂ）となシ、残シの半分が反射光（Ｃ）
となる。透過光（Ｂ）はディスクによシ反射されて反射
光（Ｂ′）となり、更にハーフプリズム（３）にて反射
されてフォトセンサ（７）に向う情報光（Ｄ）となる。The conventional pickup device described above has the following problems. That is, noise is likely to occur due to mutual interference of tracking error signals, RF multiplied signals, and relatively low-frequency light. FIG. 5 shows the half prism (3), which is one of the causes of noise generation, and the interference effect between the laser beam light passing through it. In the figure, the incident light (A) is dependent on the half prism (3), about half of which is transmitted light (B), and the remaining half is reflected light (C).
becomes. The transmitted light (B) is reflected by the disk to become reflected light (B'), and further reflected by the half prism (3) to become information light (D) directed toward the photosensor (7).
一方、反射光（Ｃ）はハーフプリズム（３）の壁面（３
Ｂ’）によって約１％前後が反射され、残りがハーフプ
リズム（３）の位置決め兼保持用の基台壁面（９）にて
反射され、両者が反射光（０）となる。On the other hand, the reflected light (C) is reflected from the wall surface (3) of the half prism (3).
About 1% of the light is reflected by B'), and the rest is reflected by the base wall surface (9) for positioning and holding the half prism (3), and both become reflected light (0).
而して、情報を含んだ光（Ｄ）と情報を何等含んでいな
い反射光１）が相互に干渉し、その干渉波が７オトセン
サ（７）に入射する１第６図は、トラッキングエラー信
号に干渉ノイズが重畳された波形を示す。第１図に図示
した光学系では、トラッキングエラー信号のＰ−Ｐ値に
対して干渉ノイズレベルが一１ＱｄＢから一２０ｄＢに
達することがあシ、トラッキングサーボ動作が不良とな
ることがある。ＲＦ倍信号対しても同様の干渉波が重畳
され、再生音声或いは映像の質を低下させる。Therefore, the light (D) containing information and the reflected light 1) that does not contain any information interfere with each other, and the interference wave enters the sensor (7) 1. Figure 6 shows the tracking error signal. shows a waveform with interference noise superimposed on it. In the optical system shown in FIG. 1, the interference noise level may reach 11 QdB to 120 dB with respect to the P-P value of the tracking error signal, and the tracking servo operation may become defective. Similar interference waves are superimposed on the RF multiplied signal, degrading the quality of reproduced audio or video.
上述した干渉ノイズを低減したものとして、アメリカ特
許第４２８２５９８号がある。これは、ハーフプリズム
又は偏光ビームスプリッタを入射光軸に対して若干傾け
て配置し、ディスクからの反射光（Ｄ）と反射光（Ｃ′
）の光路に角度差を持たせ、干渉をし難くするものであ
る（第７図参照）。U.S. Pat. No. 4,282,598 discloses a method for reducing the above-mentioned interference noise. This is achieved by arranging a half prism or polarizing beam splitter at a slight angle with respect to the incident optical axis, and the reflected light (D) and reflected light (C') from the disk.
) to make it difficult for interference to occur (see Figure 7).
斯かる従来技術に於いては、シリンドリカルレンズ（６
）の光軸をも傾けて取付けねばならず、また７オトセン
サ（７）の機械的な配置にも制約がある為、約１°程度
の比較的わずかな角度しか傾けられないことが実験によ
シ判明し大。ハーフプリズムの部品精度のパラつき、そ
れを配置する時の組立て精度のパラつき等により、プリ
ズムの角度を約１傾ける従来技術では、充分な効果が得
られないことも判明した。In such conventional technology, a cylindrical lens (6
) has to be installed with the optical axis of the sensor (7) tilted, and there are restrictions on the mechanical placement of the sensor (7), so experiments have shown that it can only be tilted at a relatively small angle of about 1°. It's obvious. It has also been found that the conventional technique of tilting the prism angle by about 1 cannot produce sufficient effects due to variations in the precision of the parts of the half prism and variations in the assembly precision when arranging the half prisms.
ハ、発明の目的
本発明は上述した欠点を解消し、確実番こ干渉ノイズを
低減せんとするものである。C. OBJECTS OF THE INVENTION The present invention aims to eliminate the above-mentioned drawbacks and to reduce reliable interference noise.
二、発明の構成
本発明に於いては、光ビームの入射面若しくは出射面と
して利用しないハーフプリズム若しくは偏光ビームスプ
リッタの面を、光乱反射面及び若しくは光吸収面として
、不必要な反射光を抑制したものである＝
ホ、実施例
第２図は本発明に係るピックアップ装置に使用するハー
フプリズム（３）を示す。略直方体形状のハーフプリズ
ム（３）の、光ビームの入射面若しくは出射面の何れで
もない面を、光学的に粗い面（３ａ）とし、更にその表
面に光を吸収し易い膜（３ｂ）を形成するものである。2. Structure of the Invention In the present invention, the surface of the half prism or polarizing beam splitter that is not used as the incident surface or exit surface of the light beam is used as a light scattering reflection surface and/or a light absorption surface to suppress unnecessary reflected light. Embodiment FIG. 2 shows a half prism (3) used in a pickup device according to the present invention. The surface of the substantially rectangular parallelepiped half prism (3) that is neither the incident surface nor the exit surface of the light beam is an optically rough surface (3a), and a film (3b) that easily absorbs light is provided on the surface. It is something that forms.
即ち、ハーフプリズム（３）の−面を粗ずシ仕上げにす
ることによシ粗い面（乱反射面）（３ａ）を形成し、更
に墨、タール、黒色系塗料等を蒸着、吹付け、塗布等し
て光吸収面（３ｂ）を形成するものである。That is, the - side of the half prism (3) is roughened to form a rough surface (diffuse reflection surface) (3a), and then ink, tar, black paint, etc. are vapor deposited, sprayed, or applied. This forms a light absorption surface (3b).
斯かるハーフプリズム（３）を使用した場合、第６図に
示す如く反射光（Ｃ）の一部は乱反射面（６ａ）にて乱
反射（発散）され、マタ、乱反射面（３Ｂ）を透過した
反射光（Ｃ）は光吸収面（３ｂ）にて吸収される為、情
報を含んだ光（Ｄ）と光路を同じくする光は著しく減少
することとなる。When such a half prism (3) is used, as shown in Figure 6, a part of the reflected light (C) is diffusely reflected (divergent) by the diffusely reflecting surface (6a) and then transmitted through the diffusely reflecting surface (3B). Since the reflected light (C) is absorbed by the light absorption surface (3b), the amount of light that shares the same optical path as the information-containing light (D) is significantly reduced.
第４図に、本発明によるハーフプリズム（３）を使用し
た場合のトラッキングエラー信号を示しておシ、従来技
術に比較して干渉ノイズレベルが著しく低下しているこ
とが分る。FIG. 4 shows a tracking error signal when the half prism (3) according to the present invention is used, and it can be seen that the interference noise level is significantly reduced compared to the prior art.
以上述べた実施例はハーフプリズムを使用した場合であ
るが、偏光ビームスプリッタにも適用できる。Although the embodiment described above uses a half prism, it can also be applied to a polarizing beam splitter.
へ、発明の効果
以上述べた本発明に依れば、不必要な光は乱反射及び若
しくは吸収するように為し、情報を含んだ光の光路と一
致させないように構成したので、従来のものに比較して
、斯かる不必要な光の強度を名以下に減少させることが
でき、干渉ノイズレベルも１［］ｄＢ以上の改善が達成
され、更にＲＦ倍信号の干渉波の重畳もかなり低レベル
に抑えることができる。B. Effects of the Invention According to the present invention described above, unnecessary light is diffusely reflected and/or absorbed, and is configured so as not to coincide with the optical path of light containing information. In comparison, the intensity of such unnecessary light can be reduced to below average, the interference noise level has been improved by more than 1 dB, and the superposition of interference waves of the RF multiplied signal is also at a considerably low level. can be suppressed to
また、従来のピックアップ装置に於いては、６ビームを
利用してトラッキングエラー信号を作成する場合、斯か
るトラッキングエラー信号を得る為の一対の７オトセン
サ（７ａ）（７ｂ）の何れか一方にのみ本来不必要な光
かあｆｃ＃）、フォトセンサ（７Ｂ）（７ｂ）に後続接
続される回路平秤にてトラッキングエラー信号を作成す
る過程に於いて、不所望な直流成分が発生することとな
っていｆＣが、本発明に依れば、斯かる直流成分も減少
させることかできる。In addition, in the conventional pickup device, when creating a tracking error signal using 6 beams, only one of the pair of 7 sensors (7a) (7b) is used to obtain the tracking error signal. In the process of creating a tracking error signal in the circuit balance that is connected subsequently to the photo sensor (7B) (7b), an undesired DC component may be generated. According to the present invention, such DC component can also be reduced.
第１図は光学式ピックアップ装置を示す図、第２図は本
発明に係るハーフプリズムを示す図、第６図はその動作
の説明に供する図、第４図はその特性図、第５図は従来
のハーフプリズムの動作の説明に供する図、第６図はそ
の特性図、第７図は従来の他のハーフプリズムの動作の
説明に供する図である。
（３）はハーフプリズム、（３Ｂ）は光乱反射面、（３
ｂ）は光吸収面。FIG. 1 is a diagram showing an optical pickup device, FIG. 2 is a diagram showing a half prism according to the present invention, FIG. 6 is a diagram for explaining its operation, FIG. 4 is a characteristic diagram thereof, and FIG. 5 is a diagram showing a half prism according to the present invention. FIG. 6 is a diagram for explaining the operation of a conventional half prism, FIG. 6 is a characteristic diagram thereof, and FIG. 7 is a diagram for explaining the operation of another conventional half prism. (3) is a half prism, (3B) is a light-diffusing reflective surface, (3
b) is a light absorption surface.
Claims (1)
リズム若しくは偏光ビームスプリッタを有する光学式ピ
ックアップ装置であって、 光ビームの入射面若しくは出射面として利用しない前記
ハーフプリズム若しくは偏光ビームスプリッタの面を光
乱反射面及び若しくは光吸収面としたことを特徴とする
光学式ピックアップ装置。(1) An optical pickup device having a substantially rectangular parallelepiped-shaped half prism or polarizing beam splitter for separating light beams, the surface of said half prism or polarizing beam splitter not being used as an incident surface or exit surface of the light beam. An optical pickup device characterized in that the surface is a light-scattering reflective surface and/or a light-absorbing surface.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59129658A JPS619845A (en) | 1984-06-22 | 1984-06-22 | Optical pickup device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59129658A JPS619845A (en) | 1984-06-22 | 1984-06-22 | Optical pickup device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS619845A true JPS619845A (en) | 1986-01-17 |
Family
ID=15014947
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP59129658A Pending JPS619845A (en) | 1984-06-22 | 1984-06-22 | Optical pickup device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS619845A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS62167643A (en) * | 1986-01-20 | 1987-07-24 | Sanyo Electric Co Ltd | Optical head |
| JPH04205929A (en) * | 1990-11-30 | 1992-07-28 | Nec Corp | Prism and optical head for optical disk device using the prism |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58175149A (en) * | 1982-04-07 | 1983-10-14 | Hitachi Ltd | Optical pickup device |
-
1984
- 1984-06-22 JP JP59129658A patent/JPS619845A/en active Pending
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58175149A (en) * | 1982-04-07 | 1983-10-14 | Hitachi Ltd | Optical pickup device |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS62167643A (en) * | 1986-01-20 | 1987-07-24 | Sanyo Electric Co Ltd | Optical head |
| JPH04205929A (en) * | 1990-11-30 | 1992-07-28 | Nec Corp | Prism and optical head for optical disk device using the prism |
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