JPH0656673B2 - Light pickup - Google Patents
Light pickupInfo
- Publication number
- JPH0656673B2 JPH0656673B2 JP3905185A JP3905185A JPH0656673B2 JP H0656673 B2 JPH0656673 B2 JP H0656673B2 JP 3905185 A JP3905185 A JP 3905185A JP 3905185 A JP3905185 A JP 3905185A JP H0656673 B2 JPH0656673 B2 JP H0656673B2
- Authority
- JP
- Japan
- Prior art keywords
- light
- signal
- optical
- recording medium
- divided
- 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.)
- Expired - Fee Related
Links
Description
【発明の詳細な説明】 〔技術分野〕 本発明は、磁気的に情報が記録された記録媒体から、磁
気光学効果を利用して情報を読み出し光ピツクアツプに
関する。Description: TECHNICAL FIELD The present invention relates to an optical pickup for reading information from a recording medium on which information is magnetically recorded by utilizing a magneto-optical effect.
〔従来技術〕 近年、光学的に情報が記録、再生され、しかも書き換え
が可能な所謂光磁気記録媒体や、このような媒体から情
報を再生する光ピツクアツプの研究、開発が盛んに行な
われている。上記光磁気記録媒体からの信号再生は、通
常カー効果やフアラデイー効果と呼ばれる磁気光学効果
を利用して行なわれる。即ち、媒体に照射された光は、
記録情報に従って偏光面が回転されて反射或いは透過さ
れるが、その回転成分を偏光板等の素子で強度変調に変
換して信号検出を行なうものである。また、この偏光面
の回転角は大略１゜前後で、その為、偏光素子を通して
得られる信号成分は微小であり、信号検出の為の光ピツ
クアツプには幾つかの工夫がなされている。[Prior Art] In recent years, so-called magneto-optical recording media in which information is optically recorded and reproduced and which can be rewritten, and optical pickups for reproducing information from such media have been actively researched and developed. . Signal reproduction from the magneto-optical recording medium is usually performed by utilizing a magneto-optical effect called Kerr effect or Faraday effect. That is, the light applied to the medium is
Although the plane of polarization is rotated and reflected or transmitted according to the recorded information, the rotation component is converted into intensity modulation by an element such as a polarizing plate and signal detection is performed. Further, the rotation angle of this polarization plane is approximately 1 °, so that the signal component obtained through the polarization element is minute, and some measures have been taken in the optical pickup for signal detection.
第１０図は、従来の光ピツクアツプの構成例を示す概略
図である。図において、半導体レーザ（以下ＬＤと記
す）１から発せられた光束は、コリメータレンズ２で平
行光束に変換される。平行光束は、その後ビーム・スプ
リツター３を通過し対物レンズ４により、記録媒体５上
に大略φ１μｍの微小スポツトに集光される。記録媒体
５から反射された光束は、カー効果及びフアラデイー効
果により偏光面変調を受け、再び対物レンズ４を通過
し、ビームスプリツター３により入射光束と分離され
る。分離された光束は、第２のビーム・スプリツタ６に
より一部反射され、レンズ系７を通り光センサ８に入射
する。レンズ系７は周知の方式、例えば非点収差系、ナ
イフエツジ系、フーコープリズム系で構成されており、
記録媒体５と対物レンズ４との間隔の情報即ちオートフ
オーカス（以下ＡＦと記す）誤差信号が光センサーより
得られる。又、これも周知のプツシエ・プル法等で情報
トラツクとのズレ、即ち、オートトラツキング（以下Ａ
Ｔと記す）誤差信号が得られる。これらの誤差信号を図
示していない対物レンズの駆動系（アクチユエータ）に
フイード・バツクして、正確な焦点位置で正確なトラツ
クトレースを行ない信号の録再を行なう。FIG. 10 is a schematic diagram showing a configuration example of a conventional optical pickup. In the figure, a light beam emitted from a semiconductor laser (hereinafter referred to as LD) 1 is converted into a parallel light beam by a collimator lens 2. The parallel light flux then passes through the beam splitter 3 and is focused by the objective lens 4 on the recording medium 5 to a minute spot of approximately φ1 μm. The light beam reflected from the recording medium 5 undergoes polarization plane modulation by the Kerr effect and the Faraday effect, passes through the objective lens 4 again, and is separated from the incident light beam by the beam splitter 3. The separated light flux is partially reflected by the second beam splitter 6, passes through the lens system 7, and enters the optical sensor 8. The lens system 7 is composed of a known system, for example, an astigmatism system, a knife edge system, a Foucault prism system,
Information on the distance between the recording medium 5 and the objective lens 4, that is, an autofocus (hereinafter referred to as AF) error signal is obtained from the optical sensor. Further, this is also a deviation from the information track by the well-known pushier pull method, that is, auto tracking (hereinafter referred to as A
An error signal (denoted as T) is obtained. These error signals are fed back to a drive system (actuator) of an objective lens (not shown) to perform accurate track tracing at an accurate focus position to record / reproduce signals.
第２のビーム・スプリツター６を通過する残りの光束は
１／２波長板９を通り、偏光ビーム・スプリツター１０
にて２方向に分割される。１／２波長板の光学的結晶軸
を入射光束の偏光軸に対し22.5゜傾むけて配置すると、
偏光ビームスプリツター１０により２分割される光量は
等しく、且つ偏光板をそれぞれの光束に４５゜、−４５
゜の透過軸を持たせて配置したものと等価になる。２分
割された光束はそれぞれセンサー集光レンズ１１，１２
にて信号検出用センサー１３，１４に集光する。そし
て、信号検出用センサー１３，１４からの電気信号を差
分する（差動検出）事により、記録媒体上の情報の検出
が行なえる。The remaining light flux passing through the second beam splitter 6 passes through the half-wave plate 9 and passes through the polarized beam splitter 10.
Is divided into two directions. When the optical crystal axis of the half-wave plate is arranged at an angle of 22.5 ° with respect to the polarization axis of the incident light beam,
The amount of light split into two by the polarization beam splitter 10 is equal, and the polarizing plate is divided into 45 ° and −45 ° for each luminous flux.
This is equivalent to the arrangement with a transmission axis of °. The two divided light beams are respectively sensor condenser lenses 11 and 12
The light is focused on the signal detecting sensors 13 and 14. Then, the information on the recording medium can be detected by making a difference between the electric signals from the signal detection sensors 13 and 14 (differential detection).
この差動検出法の利点を以下に説明する。第１１図
（Ａ），（Ｂ）は夫々１／２波長板９と偏光ビームスプ
リツター１０により分割され、センサー１４，１３に到
達する信号振幅成分を示す。縦軸を入射光束の偏光方向
とすると記録媒体５より反射された光束は、光磁気パタ
ーンの磁区の向き（上向き又は下向き）により、その偏
光面がθＫ又は−θＫ回転する。１／２波長板９と偏光
ビームスプリツター１０の組合せは、透過軸が４５゜傾
けて偏光板を配置した系と等価であるから、仮想の透過
軸（４５゜傾いた破線の軸）への投影成分の差Ｓ１と
Ｓ′１が信号振幅成分となる。θＫと−θＫは、光磁気
パターンによって時間的に変化する為、信号強度変化は
第１２図（Ａ），（Ｂ）に示すように分割された光束
で、それぞれ位相が１８０゜ずれる。これらの光信号を
センサー１３，１４で受光する。光磁気信号は、以上の
如く位相が反射するが、通常ノイズ成分（記録媒体から
のノイズ、ＬＤ光のゆらぎノイズ）がこれらの信号に乗
り、このノイズ成分は同相となる。The advantages of this differential detection method will be described below. 11 (A) and 11 (B) show signal amplitude components reaching the sensors 14 and 13, respectively, which are divided by the half-wave plate 9 and the polarization beam splitter 10. When the vertical axis is the polarization direction of the incident light beam, the light beam reflected from the recording medium 5 has its polarization plane rotated by θ K or −θ K depending on the direction (upward or downward) of the magnetic domain of the magneto-optical pattern. Since the combination of the half-wave plate 9 and the polarization beam splitter 10 is equivalent to a system in which the transmission axis is inclined by 45 ° and the polarizing plate is arranged, the virtual transmission axis (axis of the broken line inclined by 45 °) The difference S 1 between projection components and S ′ 1 becomes the signal amplitude component. Since θ K and −θ K change with time according to the magneto-optical pattern, the change in signal intensity is a light beam divided as shown in FIGS. 12A and 12B, and the phases thereof are shifted by 180 °. These optical signals are received by the sensors 13 and 14. Although the phase of the magneto-optical signal is reflected as described above, a noise component (noise from the recording medium, fluctuation noise of the LD light) normally rides on these signals, and the noise component has the same phase.
従って、センサー１３，１４から得られる信号の差動を
とると信号成分は強め合い、ノイズ成分は減少する。光
学系の配置が正確に行なわれていれば、それぞれのセン
サーから得られる信号成分Ｓ1 2とＳ′1 2は等しく、又ノ
イズ振幅も等しいので、信号は２倍となりノイズは零と
なる。このように、第１０図に示したような差動検出法
はＳ／Ｎの良い信号が検出出来る利点がある。Therefore, when the signals obtained from the sensors 13 and 14 are differentiated, the signal components are strengthened and the noise components are reduced. If the optical system is arranged correctly, the signal components S 1 2 and S ′ 1 2 obtained from the respective sensors are equal and the noise amplitude is also equal, so that the signal is doubled and the noise is zero. As described above, the differential detection method as shown in FIG. 10 has an advantage that a signal with good S / N can be detected.
しかしながら、上述したような従来の光ピツクアツプは
部品が多く、小型化、低コスト化を図る上で不利であ
る。また、複数の光検出器等を正確に位置決めさせねば
ならず、調整も煩雑であった。However, the conventional optical pickup as described above has many parts and is disadvantageous in terms of downsizing and cost reduction. Further, it is necessary to accurately position a plurality of photodetectors and the like, and the adjustment is complicated.
本発明の目的は、上述の従来例の欠点を解消し、コンパ
クトに構成出来、また光学調整も簡単な光ピツクアツプ
を提供することにある。SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned drawbacks of the conventional example and to provide an optical pickup which can be compactly constructed and whose optical adjustment is simple.
本発明の上記目的は、受光面が複数の部分に分割された
単一の光検出器と、磁気的に情報が記録された記録媒体
からの光束を分割し、分割された光束を前記光検出器の
各々異なる部分に導く手段と、前記分割された一方の光
束の偏光方向９０゜回転する手段と、前記偏光方法の回
転された光束と他方の光束とを各々強度変調された光束
に変換する検光子と、前記光検出器の各部分の出力から
情報信号を差動検出する手段とから光ピツクアツプを構
成することによって達成される。The above object of the present invention is to divide a light beam from a single photodetector whose light receiving surface is divided into a plurality of portions and a recording medium on which information is magnetically recorded, and to detect the divided light beam by the photodetection. To guide different parts of the beam splitter, to rotate the polarization direction of the one of the divided light beams by 90 °, and to convert the rotated light beam and the other light beam of the polarization method into intensity-modulated light beams. This is accomplished by constructing an optical pickup with an analyzer and means for differentially detecting an information signal from the output of each part of the photodetector.
第１図に本発明の光ピツクアツプの構成例を示す、ＬＤ
１５より発せられた光束は、コリメーターレンズ１６に
て平行光束となり、第１のビームスプリツター１７で反
射され、対物レンズ１８により記録媒体１９上に微小ス
ポツトに集光する。記録媒体１９からの反射光束は再び
対物レンズ１８を通り、第１のビームスプリツター１７
を通過し、第２ビーム・スプリツター２０に入射し、２
光束に分離される。第２のビーム・スプリツター２０に
て反射された第１の分割光２１は、偏光板の如き偏光素
子２２を通り、集束レンズ２５にて光センサー２４に向
って集光する。又、偏光素子２２は、集束レンズ２５と
光センサー２４の間に配置しても同じ効果が得られる。
他方、第２のビームスプリツター２０を通過した第２の
分割光２６は、ビームスプリツター２０の底面の反射部
２７で反射され１／２波長板２３、偏光素子２２を通過
し、集束レンズ２５で光センサー２４にむかい集光され
る。FIG. 1 shows an example of the LD configuration of the optical pickup of the present invention.
The light beam emitted from 15 becomes a parallel light beam by the collimator lens 16, is reflected by the first beam splitter 17, and is condensed by the objective lens 18 on the recording medium 19 in a minute spot. The reflected light beam from the recording medium 19 passes through the objective lens 18 again, and the first beam splitter 17
Through the second beam splitter 20
It is split into luminous flux. The first split light 21 reflected by the second beam splitter 20 passes through a polarizing element 22 such as a polarizing plate, and is focused by a focusing lens 25 toward an optical sensor 24. Further, the same effect can be obtained by disposing the polarizing element 22 between the focusing lens 25 and the optical sensor 24.
On the other hand, the second split light 26 that has passed through the second beam splitter 20 is reflected by the reflecting portion 27 on the bottom surface of the beam splitter 20, passes through the half-wave plate 23 and the polarizing element 22, and is focused by the focusing lens 25. Then, the light is focused on the optical sensor 24.
光センサー２４は分割光束２１，２６が集束レンズ２５
にて集光される焦点面より離れた位置に配置される。光
センサー２４は例えば第２図（Ａ）に示すように、その
受光面に１２分割の受光部を持っている。In the optical sensor 24, the divided luminous fluxes 21 and 26 are focusing lenses 25.
It is placed at a position away from the focal plane where the light is focused at. The optical sensor 24 has, for example, as shown in FIG. 2A, a 12-divided light receiving portion on its light receiving surface.
以下第１図の構成でＡＦ，ＡＴ誤差信号の検出と情報信
号の差動検出が行なえる原理を説明する。The principle of AF / AT error signal detection and information signal differential detection with the configuration of FIG. 1 will be described below.
第３図は、ＡＦ信号の検出原理を示すものである。第１
図におけるＡＦ検出に必要な構成のみを第３図に示し
た。記録媒体１９が対物レンズ１８の焦点面に位置する
場合、光線は実線で示す如く進み、集束レンズ２５の焦
点Ｆに集束する。又、記録媒体１９が対物レンズ１８の
焦点面から遠ざかった場合、破線で示す如く光線は集束
レンズ２５の光軸の手前に集束する。図示していない
が、記録媒体が対物レンズ１８の焦点面より近づいた場
合、光束は集束レンズ２５の光軸を越えて集束する。従
って光センサー２４をＦ点からずらして配置した場合、
光センサー２４面上では分割されたそれぞれの光束の分
布が記録媒体の位置によりセンサー面上で小さくなった
り大きくなったりする。FIG. 3 shows the principle of AF signal detection. First
Only the structure required for AF detection in the figure is shown in FIG. When the recording medium 19 is located in the focal plane of the objective lens 18, the light rays travel as shown by the solid line and are focused on the focal point F of the focusing lens 25. Further, when the recording medium 19 moves away from the focal plane of the objective lens 18, the light rays are focused before the optical axis of the focusing lens 25 as indicated by the broken line. Although not shown, when the recording medium comes closer to the focal plane of the objective lens 18, the light flux converges beyond the optical axis of the focusing lens 25. Therefore, when the optical sensor 24 is arranged so as to be displaced from the point F,
On the surface of the optical sensor 24, the distribution of the respective divided light fluxes becomes smaller or larger on the sensor surface depending on the position of the recording medium.
光センサー２４の受光部が第２図（Ａ）の如き１２分割
に構成されている場合につき先ず説明する。対物レンズ
１８と記録媒体１９が合焦の関係にある時の光センサー
部の光束の部分を図中の斜線部で示す。今、各受光部か
らの出力をそれぞれIA,IB,IC,ID,IE,IF,IG,IH,II,IJ,
IK,ILとするＡＦ誤差信号IAFは IAF＝（ＩＡ＋ＩＢ＋ＩＥ＋ＩＦ＋ＩＧ＋ＩＨ＋ＩＫ＋ＩＬ）−（ＩＣ＋ＩＤ＋
ＩＩ＋ＩＪ） で得られる。First, the case where the light receiving portion of the optical sensor 24 is divided into 12 parts as shown in FIG. The portion of the light flux of the optical sensor portion when the objective lens 18 and the recording medium 19 are in the in-focus relationship is shown by the hatched portion in the figure. Now, the outputs from the respective light receiving units are I A , I B , I C , I D , I E , I F , I G , I H , I I , I J ,
The AF error signal I AF for I K and I L is I AF = (I A + I B + I E + I F + I G + I H + I K + I L ) − (I C + I D +
I I + I J ).
又、第２図（Ｂ）に示す如く同心状の受光部に分割され
た光センサーの場合はそれぞぞれの出力をIA,IB,IC,ID,
IE,IF,IG,IHとする、ＡＦ誤差信号IAFは IAF＝（ＩＡ＋ＩＢ＋ＩＥ＋ＩＦ）−（ＩＣ＋ＩＤ＋ＩＧ＋ＩＨ） で得られる。Further, as shown in FIG. 2B, in the case of an optical sensor divided into concentric light receiving parts, the respective outputs are I A , I B , I C , I D ,
The AF error signal I AF, which is I E , I F , I G , I H , is obtained by I AF = (I A + I B + I E + I F ) − (I C + I D + I G + I H ).
なお片側の光束に関してのみの演算によってもＡＦ誤差
信号は得られる。第２図（Ａ）の例で云えば、 IAF＝（ＩＡ＋ＩＢ＋ＩＥ＋ＩＦ）−（ＩＣ＋ＩＤ） でも得られる。Note that the AF error signal can be obtained also by the calculation of only the light flux on one side. In the example of FIG. 2 (A), I AF = (I A + I B + I E + I F ) − (I C + I D ) can also be obtained.
次にＡＴ信号の検出原理を説明する。Next, the principle of detecting the AT signal will be described.
記録媒体１９の記録媒体面近傍は、通常大略１／８波長
の深さの溝が設けられており、この溝をガイドとして信
号の録再を行なう。この溝から反射される光束が再び対
物レンズ１８を通って形成するフアーフイールドパター
ンは衆知の如く、光スポツトと溝との位置関係で変る。
第４図にその様子を示す。第４図上部の図は溝と光スポ
ツトとの位置関係、下部の図はフアーフイールドパター
ンの強度分布を示す。A groove having a depth of about ⅛ wavelength is usually provided in the vicinity of the recording medium surface of the recording medium 19, and signals are recorded / reproduced using the groove as a guide. The far field pattern formed by the light beam reflected from the groove again passing through the objective lens 18 changes depending on the positional relationship between the optical spot and the groove, as is well known.
Figure 4 shows the situation. The upper part of FIG. 4 shows the positional relationship between the groove and the optical spot, and the lower part shows the intensity distribution of the far field pattern.
従って、第２図（Ａ）の分割センサーの場合Ｔ−Ｔ′の
方向を溝の走る方向（信号トラツク方向）に合わせると
ＡＴ誤差信号IATは、 IAT＝（ＩＡ＋ＩＣ＋ＩＥ＋ＩＧ＋ＩＩ＋ＩＫ）− （ＩＢ＋ＩＤ＋ＩＦ＋ＩＨ＋ＩＪ＋ＩＬ） で得られる。Therefore, when the direction of the second view (A) if the divided sensor T-T of 'match the orientation (signal track direction) running grooved AT error signal I AT is, I AT = (I A + I C + I E + I G + I I + I K) - obtained in (I B + I D + I F + I H + I J + I L).
又、第２図（Ｂ）の分割センサーの場合、 IAT＝（ＩＡ＋ＩＣ＋ＩＥ＋ＩＧ）−（ＩＢ＋ＩＤ＋ＩＦ＋ＩＨ） で得られる。In the case of split sensor of FIG. 2 (B), I AT = ( I A + I C + I E + I G) - obtained in (I B + I D + I F + I H).
ＡＴ信号においても１方のビームのみ受光する受光部の
出力の演算でも誤差信号を得ることが出来る。The error signal can also be obtained by calculating the output of the light receiving unit that receives only one beam of the AT signal.
次に光磁気により情報信号が差動で得られる理由を示
す。Next, the reason why the information signal is obtained differentially by magneto-optical will be shown.
第５図において、記録媒体１９へ入射する 光束の偏光面の方向をＸとし、それと垂直方向をＹとす
る。In FIG. 5, the direction of the plane of polarization of the light beam incident on the recording medium 19 is X, and the direction perpendicular thereto is Y.
記録媒体１９からの反射光は、第５図（Ａ）の如く磁気
−光学効果によりその偏光面が僅な角度θＫだけ傾いて
いる。この傾きは、磁区の上，下向きで時計方向あるい
は反時計方向（θＫ又は−θＫ）であり、その量は大略
１゜程度である。第１図におけるビームスプリツター２
０により反射された光束２１は、偏光素子を通過する。
偏光素子２２の透過軸を、Ｘ方向から大略４５゜傾けて
おくと、偏光面の傾き方向により第５図において、 Ｓ1 2＝｛cos(45゜-θK)｝２ −｛cos(45゜+θK｝２ の信号強度成分が得られる。The light reflected from the recording medium 19 has its plane of polarization inclined by a slight angle θ K due to the magneto-optical effect as shown in FIG. This inclination is upward or downward in the magnetic domain and is clockwise or counterclockwise (θ K or −θ K ) and its amount is about 1 °. Beam Splitter 2 in Figure 1
The light flux 21 reflected by 0 passes through the polarizing element.
When the transmission axis of the polarizing element 22 is tilted by about 45 ° from the X direction, S 1 2 = {cos (45 ° -θ K )} 2- {cos (45 A signal strength component of ++ θ K } 2 is obtained.
又、第２の分割光２６は偏光素子２２を通過する前に、
１／２波長板２３を通過するので、光束２６の偏光方向
の状態は第５図（Ｂ）の如く、光束２１と比べ９０゜回
転している。Also, before the second split light 26 passes through the polarizing element 22,
Since the light beam 26 passes through the half-wave plate 23, the state of the polarization direction of the light beam 26 is rotated by 90 ° as compared with the light beam 21 as shown in FIG.
従って、偏光素子２２を通過すると、 Ｓ′1 2＝｛cos(45゜-θK)｝２−｛cos(45゜+θK)｝２ の強度信号成分が生じる。Therefore, when passing through the polarizing element 22, S '1 2 = { cos (45 ° -θ K)} 2 - {cos (45 ° + θ K)} 2 of the intensity signal components occurs.
Ｓ1 2とＳ′1 2は便宜上、信号Ｐ−Ｐ成分のみを示したも
のであるが、第５図（Ａ），（Ｂ）からも理解出来るよ
うにθＫの回転の場合、光束２１は最大、光束２６は最
小の信号振巾となる。S 1 2 and S '1 2 for convenience, but illustrates only the signal P-P components, FIG. 5 (A), in the case where the rotation of the theta K as can be seen from (B), the light beam 21 Is the maximum and the luminous flux 26 is the minimum.
即ち、光磁気信号により偏光面の回転を第１図の様な構
成で検出すると、光束２１と光束２６から得られる強度
変調は位相反転している事になる。従って、情報信号Ｉ
Ｓは 第２図（Ａ）の場合、 ＩＳ＝（ＩＡ＋ＩＢ＋ＩＣ＋ＩＤ＋ＩＥ＋ＩＦ）− （ＩＧ＋ＩＨ＋ＩＩ＋ＩＪ＋ＩＫ＋ＩＬ） 又、第２図（Ｂ）の場合、 ＩＳ＝（ＩＡ＋ＩＢ＋ＩＣ＋ＩＤ）−（ＩＥ＋ＩＦ＋ＩＧ＋ＩＨ） で得られ、情報信号が差動検出される。That is, when the rotation of the plane of polarization is detected by the magneto-optical signal with the configuration shown in FIG. 1, the intensity modulation obtained from the light beam 21 and the light beam 26 has a phase inversion. Therefore, the information signal I
In the case of FIG. 2 (A), S is I S = (I A + I B + I C + I D + I E + I F ) − (I G + I H + I I + I J + I K + I L ) and FIG. 2 (B) In this case, I S = (I A + I B + I C + I D ) − (I E + I F + I G + I H ), and the information signal is differentially detected.
第１０図に示す従来構成と第１図に示す本発明の構成か
ら明らかな様に本発明においては、光センサーが３個か
ら１個、集束レンズ３個から１個、ビームスプリツター
が３個から２個と大幅な部品減少が図られており、小型
化、低コスト化に有利な構成である。As is apparent from the conventional configuration shown in FIG. 10 and the configuration of the present invention shown in FIG. 1, in the present invention, three to one optical sensors, three to one focusing lenses, and three beam splitters are provided. Therefore, the number of parts is greatly reduced to two, which is advantageous for downsizing and cost reduction.
更に、第１図における各光学素子を１体化する事によ
り、組立て時の光学調整が容易となり、且つ使用時の軸
ズレも防げ信頼性の高い光ピツクアツプを実現出来る。
例えば、第６図はビームスプリツター１７，２０、１／
２波長板２３、偏光素子２２を接着等で１体化した例を
示したものである。又、第７図は１／２波長板をビーム
スプリツター２０の反射面の直後に配置した例で、第６
図と異なり、同一サイズの平行四辺形ブロツク３１，３
２を使用出来素子加工が簡略化される。Further, by integrating each optical element in FIG. 1, it is possible to easily perform optical adjustment during assembly, prevent axial misalignment during use, and realize a highly reliable optical pickup.
For example, FIG. 6 shows beam splitters 17, 20, 1 /
It shows an example in which the two-wave plate 23 and the polarizing element 22 are integrated into one body by adhesion or the like. Further, FIG. 7 shows an example in which a half-wave plate is arranged immediately after the reflecting surface of the beam splitter 20.
Unlike the figure, the parallelogram blocks 31, 3 of the same size
2 can be used and the element processing is simplified.
又、第８図に示す如く、１／２波長板２３の代りに第２
の光束２６の反射面２３′に誘電膜、金属膜等をい設け
る事により偏光面を回転させる事も可能である。第９図
は１回の反射で偏光面を９０゜回転させる事が困難な場
合、多数回の反射で所望の回転角を得る例を示したもの
である。Moreover, as shown in FIG.
It is also possible to rotate the plane of polarization by providing a dielectric film, a metal film, or the like on the reflecting surface 23 'of the luminous flux 26. FIG. 9 shows an example of obtaining a desired rotation angle by multiple reflections when it is difficult to rotate the polarization plane by 90 ° by one reflection.
又、ＡＦ，ＡＴ誤差信号、情報信号を検出する為、それ
ぞれの受光部から得られる信号を演算する必要がある
が、光センサー内に受光部の他、演算用の差動ＡＭＰを
内蔵すると外乱ノイズの飛び込みに強い信号検出が可能
である。Further, in order to detect the AF and AT error signals and the information signal, it is necessary to calculate the signals obtained from the respective light receiving parts. It is possible to detect signals that are strong against noise jumps.
以上説明したように、本発明は記録媒体からの光束を分
割し、受光面が分割された単一の光検出器で差動検出す
るようにしたので、 １． 光ピックアップがコンパクトに構成できる。As described above, according to the present invention, the light flux from the recording medium is split and differential detection is performed by a single photodetector having a split light receiving surface. The optical pickup can be made compact.
２． 差動検出により信号検出のＳ／Ｎ比を向上させ
る。2. The differential detection improves the signal detection S / N ratio.
３． 部品数を減らし、低コスト化できる。3. The number of parts can be reduced and the cost can be reduced.
４． 部品の一体化により、更に高信頼性のピツクアツ
プが実現出来る。4. Higher reliability pick-up can be realized by integrating the parts.
５． 光検出器が一つなので、検出器間の特性のバラツ
キに対する配慮か少なくてすみ、位置調整などの簡単で
ある。5. Since there is only one photodetector, there is little consideration for variations in characteristics between the detectors, and position adjustment is simple.
６． 光検出器と同一チツプ上に各信号の演算回路を作
成することによって外乱ノイズに強い信号検出が可能で
ある。6. By creating an arithmetic circuit for each signal on the same chip as the photodetector, it is possible to detect a signal that is strong against disturbance noise.
等の効果が得られる。And so on.
第１図は本発明の光ピツクアツプの構成例を示す概略
図、第２図は本発明に用いる光検出器の受光面を示す
図、第３図は本発明におけるＡＦ信号の検出原理を説明
する図、第４図は本発明におけるＡＴ信号の検出原理を
説明する図、第５図は本発明における情報信号の検出原
理を説明する図、第６図、第７図、第８図及び第９図は
夫々第１図の光ピツクアツプの変形例を示す概略図、第
１０図は従来の光ピツクアツプの構成例を示す概略図、
第１１図及び第１２図は夫々差動検出の原理を説明する
図である。 １５……半導体レーザー １６……コリメーターレンズ １７，２０……ビームスプリツター １８……対物レンズ １９……記録媒体 ２２，２２′……偏光素子 ２３……１／２波長板 ２４……光センサー ２５……集束レンズ ２７……反射部。FIG. 1 is a schematic diagram showing a configuration example of an optical pickup of the present invention, FIG. 2 is a diagram showing a light receiving surface of a photodetector used in the present invention, and FIG. 3 is a diagram for explaining an AF signal detection principle in the present invention. 4 and FIG. 4 are diagrams for explaining the principle of detecting an AT signal in the present invention, and FIG. 5 is a diagram for explaining the principle of detecting an information signal in the present invention, FIG. 6, FIG. 7, FIG. 8 and FIG. FIG. 10 is a schematic diagram showing a modified example of the optical pickup shown in FIG. 1, and FIG. 10 is a schematic diagram showing a configuration example of a conventional optical pickup.
11 and 12 are diagrams for explaining the principle of differential detection, respectively. 15 ... Semiconductor laser 16 ... Collimator lens 17,20 ... Beam splitter 18 ... Objective lens 19 ... Recording medium 22,22 '... Polarizing element 23 ... 1/2 wavelength plate 24 ... Optical sensor 25 ... Focusing lens 27 ... Reflector.
Claims (1)
検出器と、磁気的に情報が記録された記録媒体からの光
束を分割し、分割された光束を前記光検出器の各々異な
る部分に導く手段と、前記分割された一方の光束の偏光
方向９０゜回転する手段と、前記偏光方向の回転された
光束と他方の光束とを各々強度変調された光束に変換す
る検光子と前記光検出器の各部分の出力から情報信号を
差動検出する手段とから成る光ピツクアツプ。1. A single photodetector having a light-receiving surface divided into a plurality of portions, and a light flux from a recording medium on which information is magnetically recorded is split, and the split light flux is divided by the photodetector. Means for leading to different parts, means for rotating the polarized direction of one of the divided luminous fluxes by 90 °, and an analyzer for converting the rotated luminous flux of the polarized direction and the other luminous flux into intensity-modulated luminous fluxes. And an optical pick-up comprising means for differentially detecting an information signal from the output of each part of the photo detector.
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3905185A JPH0656673B2 (en) | 1985-02-28 | 1985-02-28 | Light pickup |
| US08/195,882 US5416755A (en) | 1985-02-28 | 1994-02-04 | Optical pickup using split beams impinging on different photo-detector areas |
| US08/195,881 US5661701A (en) | 1985-02-28 | 1994-02-04 | Optical pickup using split beams impinging on different photodetector areas |
| US08/275,328 US5488598A (en) | 1985-02-28 | 1994-07-14 | Optical pickup using split beams impinging on different photodetector areas |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3905185A JPH0656673B2 (en) | 1985-02-28 | 1985-02-28 | Light pickup |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS61198457A JPS61198457A (en) | 1986-09-02 |
| JPH0656673B2 true JPH0656673B2 (en) | 1994-07-27 |
Family
ID=12542326
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3905185A Expired - Fee Related JPH0656673B2 (en) | 1985-02-28 | 1985-02-28 | Light pickup |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0656673B2 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61258339A (en) * | 1985-05-13 | 1986-11-15 | Matsushita Electric Ind Co Ltd | Optical recording and reproducing device |
| JP2674745B2 (en) * | 1987-02-06 | 1997-11-12 | 日本電気株式会社 | Magneto-optical reproduction method |
| JP3618769B2 (en) * | 1992-12-01 | 2005-02-09 | キヤノン株式会社 | Optical information recording / reproducing device |
| JP2751899B2 (en) * | 1995-12-15 | 1998-05-18 | ソニー株式会社 | Optical pickup device |
-
1985
- 1985-02-28 JP JP3905185A patent/JPH0656673B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPS61198457A (en) | 1986-09-02 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US5488598A (en) | Optical pickup using split beams impinging on different photodetector areas | |
| JPH0731837B2 (en) | Optical pickup device | |
| JPH0690817B2 (en) | Light pickup | |
| JP3248567B2 (en) | Magneto-optical recording / reproducing device | |
| JPH03116567A (en) | Magneto-optical information reproducing device | |
| JPH0656673B2 (en) | Light pickup | |
| JPH08306091A (en) | Optical head | |
| US6396638B1 (en) | Optical pickup device capable of stable tracking | |
| JP2744635B2 (en) | Optical recording / reproducing device | |
| JP2625738B2 (en) | Optical head | |
| JP2594929B2 (en) | Optical information processing device | |
| JPH0264917A (en) | Optical head structure for magneto-optical recorder | |
| JPH02193347A (en) | Optical head structure for magneto-optical recorder | |
| JP2659239B2 (en) | Light head | |
| JPH0227736B2 (en) | ||
| JPS6223373B2 (en) | ||
| JP3085148B2 (en) | Optical pickup | |
| JPH0836781A (en) | Optical head | |
| JPH0413229A (en) | Optical information recording and reproducing device | |
| JPH0120498B2 (en) | ||
| JPS639305B2 (en) | ||
| JPH02105357A (en) | Magneto-optical disk device | |
| JPS641858B2 (en) | ||
| JPH06274929A (en) | Optical head device | |
| JPS63225947A (en) | Optical system for information recording and reproducing device for magneto-optical disk |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |