JPS5971138A - Optical head - Google Patents

Optical head

Info

Publication number
JPS5971138A
JPS5971138A JP57180250A JP18025082A JPS5971138A JP S5971138 A JPS5971138 A JP S5971138A JP 57180250 A JP57180250 A JP 57180250A JP 18025082 A JP18025082 A JP 18025082A JP S5971138 A JPS5971138 A JP S5971138A
Authority
JP
Japan
Prior art keywords
light
beam splitter
optical
optical head
split
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.)
Granted
Application number
JP57180250A
Other languages
Japanese (ja)
Other versions
JPS6310490B2 (en
Inventor
Hiroshi Inada
稲田　博司
Tadashi Nomura
正 野村
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
NEC Corp
Original Assignee
NEC Corp
Nippon Electric Co Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by NEC Corp, Nippon Electric Co Ltd filed Critical NEC Corp
Priority to JP57180250A priority Critical patent/JPS5971138A/en
Priority to EP83303435A priority patent/EP0098076A1/en
Publication of JPS5971138A publication Critical patent/JPS5971138A/en
Priority to US06/765,172 priority patent/US4615023A/en
Publication of JPS6310490B2 publication Critical patent/JPS6310490B2/ja
Granted legal-status Critical Current

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
    • G11B7/08—Disposition or mounting of heads or light sources relatively to record carriers
    • G11B7/09—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
    • G11B7/0901—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following for track following only
    • 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
    • G11B7/08—Disposition or mounting of heads or light sources relatively to record carriers
    • G11B7/085—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam into, or out of, its operative position or across tracks, otherwise than during the transducing operation, e.g. for adjustment or preliminary positioning or track change or selection
    • G11B7/08505—Methods for track change, selection or preliminary positioning by moving the head

Landscapes

  • Optical Head (AREA)
  • Moving Of The Head For Recording And Reproducing By Optical Means (AREA)
  • Optical Recording Or Reproduction (AREA)

Abstract

PURPOSE:To detect accurately the position of a tracking direction of a condensor lens to an optical head, by moving the condensor lens, a beam splitter and a prism in the tracking direction at the same time and detecting the transmitted light of the beam splitter by a 2-split optical sensor. CONSTITUTION:An incident light 30 is reflected at right angles by the beam splitter 21, the light is condensed on a spot 16 on a recording plane of a disc 17 via a 1/4 wavelength plate 6 and the condensor lens 7, the reflected light passes through the condensor lens 7 and the 1/4 wavelength plate 6 and is reflected in the same direction as the incident light, performing focus position eror detection, tracking position error detection, and information signal detection. The transmitted light at the beam splitter 21 of the incident light 30 is reflected at right angles by the prism 22 and made incident to the 2-split optical sensor 18. The condensor lens 7 is positioned at the center of the optical head and the optical axis of the incident light to the 2-split optical sensor 18 is positioned on a divided line of the 2-split optical sensor 18, then the amount of photodetection of th two optical sensors is made equal, and the difference of the two optical sensors is zero.

Description

【発明の詳細な説明】 本発明は光学手段を用いて、記録媒体上に情報を記録し
、あるいは、既に記録されている情報を読出す光学ヘッ
ドに関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical head that uses optical means to record information on a recording medium or read information that has already been recorded.

レーザー光を光源とし、とのレーザー光を外部の情報源
からのパルス状信号で変調して、ディスク面上の記録媒
体に２値的に記録し、あるいは、既に記録された情報を
読出す光学ヘッドにおいては、情報の記録あるいは、再
生を正確に行うために、焦点制御によって、記録媒体面
上が常に集光レンズの焦点位置となるように集光レンズ
の光軸方向の位置制御が行われ、また、光スポットの情
報トラックに対するトラッキング位置制御は、通常、記
録媒体上にその光スポットに最適な幅および使用レーザ
ー光の波長に最適な深さをもつ案内溝を設けて、その案
内溝に光スぎットが沿うように、集光レンズをディスク
半径方向に駆動することによって行っている。さらに、
前記光スポット（９） のトラックアクセスにおいては、通常、狭い範囲内では
、光学ヘッド内部のトラッキングアクチュエータによっ
て集光レンズのみをディスク半径方向に移動することに
よって行い、逆に広い範囲では、外部アクチュエータに
よって光学ヘッド全体を移動することによって行ってい
る。このような２段す−ボ方式においては、光スポット
が、情報トラックを追従している状態では、集光レンズ
が光学ヘッドの中心に位置するように光学ヘッドの位置
制御を行うことが望ましく、さらに、広範囲のトラック
アクセスにおいては、停止位置近傍での集光レンズの振
動を抑えることから、光学ヘッド内の一定位置に集光レ
ンズを固定した状態で、光学ヘッドを移動することが望
ましい。しかし、このような２段す−ボ方式を達成する
ためには、光学ヘッドに対する集光レンズの位置を正確
に検出することが必要であ夛、従来の２段す−ボ方式に
おいては、光学ヘッドに対する集光レンズの位置を正確
に検出することが不可能であるため、通常、外部アクチ
ュエータ専用の位置センサを使用し、外部アクチュエー
タ、すなわち、光学ヘッドは１この位置センサの出力で
ある位置信号をもとにして位置制御が行われ、集光レン
ズは前記案内溝に対する光スポットの位置信号をもとに
して位置制御が行われている。このように、集光レンズ
と光学ヘッドとは、おのおの独立に位置制御が行われて
いるため、内部アクチーエータの動作が外部アクチュエ
ータの動作に反映せず、広範囲にわたるトラック追従が
不可能であり、さらに、トラックアクセス時に光学ヘッ
ドを高速で目標トラックに向けて移動させた場合、停止
位置近傍で、集光レンズの振動が発生し、この振動がお
さまるまで、トラック追従動作が行えず、その待ち時間
だけ、トラックアクセス時間が余分にかかる欠点があっ
た。以上説明した如く、従来の光学ヘッドでは、光学式
情報記録再生装置の高性能化は不可能であった。An optical system that uses laser light as a light source and modulates the laser light with pulsed signals from an external information source to record binary information on a recording medium on a disk surface or to read information that has already been recorded. In the head, in order to accurately record or reproduce information, focus control is performed to control the position of the condenser lens in the optical axis direction so that the focus position of the condenser lens is always on the surface of the recording medium. In addition, the tracking position control of a light spot with respect to an information track is usually achieved by providing a guide groove on the recording medium with a width optimal for the light spot and a depth suitable for the wavelength of the laser beam used, and This is done by driving a condenser lens in the radial direction of the disk so that the light beam follows it. moreover,
Track access of the optical spot (9) is normally performed within a narrow range by moving only the focusing lens in the disk radial direction using a tracking actuator inside the optical head, and conversely, when accessing a wide range, an external actuator is used to move the condensing lens in the disk radial direction. This is done by moving the entire optical head. In such a two-stage laser system, when the light spot is following the information track, it is desirable to control the position of the optical head so that the condenser lens is located at the center of the optical head. Furthermore, when accessing a wide range of tracks, it is desirable to move the optical head with the condenser lens fixed at a fixed position within the optical head in order to suppress vibration of the condenser lens near the stop position. However, in order to achieve such a two-stage bow system, it is necessary to accurately detect the position of the condenser lens relative to the optical head. Since it is impossible to accurately detect the position of the focusing lens with respect to the head, a dedicated position sensor is usually used for the external actuator, and the external actuator, i.e. the optical head, receives a position signal which is the output of this position sensor. The position of the condenser lens is controlled based on the position signal of the light spot relative to the guide groove. In this way, since the positions of the condenser lens and the optical head are controlled independently, the operation of the internal actuator does not reflect the operation of the external actuator, making it impossible to track a wide range. When the optical head is moved toward the target track at high speed during track access, vibrations of the condensing lens occur near the stop position, and track following cannot be performed until the vibrations subside. However, this method has the drawback of requiring additional track access time. As explained above, it has been impossible to improve the performance of optical information recording and reproducing devices using conventional optical heads.

本発明の目的は、上記欠点を取り除くため、光学ヘッド
に対する集光レンズの正確な位置信号を発生することが
できる新規な光学ヘッドを提供することにある。SUMMARY OF THE INVENTION It is an object of the present invention to provide a new optical head capable of generating accurate position signals of the condenser lens relative to the optical head, in order to eliminate the above-mentioned drawbacks.

以下、図面を用いて本発明の詳細な説明する。Hereinafter, the present invention will be explained in detail using the drawings.

第１図は本発明による光学ヘッドの一実施例を示すブロ
ック図である。半導体レーザー２から出射されたレーザ
ー光はコリメートレンズ３、偏光ビームスプリッタ５を
通過して、ビームスプリッタ２１に入射し、その反射面
２３において、入射光を２つに分割する。分割された２
つの光のうち、反射面２３において直角方向に反射され
た光は１／４波長板６、集光レンズ７を通過してディス
ク１１の記録媒体面上の光スポット１６に集光され、情
報の記録あるいは読出しが行われる。一方、記録媒体か
らの反射光は集光レンズ７．１／４波長板を通過し、ビ
ームスプリッタ２１に入射し、反射面２３によって反射
され、その反射光は偏光ビームスプリッタ５に入射し、
反射面８において、半導体レーザー２からの入射光と分
離される。こうして入射光と分離された反射光は、ハー
フミラ−９に入射し、ここでさらに２つに分割される。FIG. 1 is a block diagram showing an embodiment of an optical head according to the present invention. The laser beam emitted from the semiconductor laser 2 passes through the collimating lens 3 and the polarizing beam splitter 5, enters the beam splitter 21, and is split into two at its reflecting surface 23. divided 2
Among the two lights, the light reflected in the right angle direction on the reflecting surface 23 passes through the quarter-wave plate 6 and the condensing lens 7, and is focused on the light spot 16 on the recording medium surface of the disk 11, where information is transmitted. Recording or reading is performed. On the other hand, the reflected light from the recording medium passes through the condensing lens 7 and the 1/4 wavelength plate, enters the beam splitter 21, is reflected by the reflective surface 23, and the reflected light enters the polarizing beam splitter 5,
At the reflective surface 8, the light is separated from the incident light from the semiconductor laser 2. The reflected light thus separated from the incident light enters the half mirror 9, where it is further divided into two.

分割された一方の光は凸レンズ１０、ナイフェツジ１１
を通過して２分割光センサ１９に入射され、焦点誤差検
出が行われる。この焦点誤差検出方法は、ナイフェツジ
方法として、従来から良く知られている技術であり、検
出された焦点誤差信号は、図には示していない焦点制御
回路を介して、焦点制御用アクチーエータ１３に帰還さ
れ、ディスク１７の記録媒体面上が常に集光レンズ７の
焦点位置となるように、トラッキング可動部４の中の集
光レンズ７のみを矢印１５で示す方向に駆動する。One of the split lights is passed through a convex lens 10 and a knife lens 11.
The light passes through and enters the two-split optical sensor 19, where focus error detection is performed. This focus error detection method is a well-known technology known as the Knifezi method, and the detected focus error signal is fed back to the focus control actuator 13 via a focus control circuit (not shown). Then, only the condenser lens 7 in the tracking movable section 4 is driven in the direction shown by the arrow 15 so that the focal position of the condenser lens 7 is always on the recording medium surface of the disk 17.

前記ハーフミラ−９で分割されたもう一方の反射光は、
２分割光センサ２０に入射され、図には示していないデ
ィスク１７の面上に設けられたトラッキング用案内溝に
対する光スポット】６のトラッキング位置誤差検出が行
われる。このトラッキング位置誤差検出方法は、プッシ
ュプル方法として従来から良く知られている方法であり
、検出されたトラッキング位置誤差信号は、図には示し
ていないトラッキング制御回路を介してトラッキングア
クチュエータ１２に帰還され、光スポット１６がトラッ
キング用案内溝の中心に位置するように、トラッキング
可動部４を矢印１４で示す方向に駆動する。トラッキン
グ可動部上にはビームスプリッタ２１、プリズム２２．
１．／４波長板および集光レンズ７が矢印１４で示す方
向に固定されているため、トラッキング可動部４を矢印
】４で示す方向（ディスク１７の半径方向）に動かすと
、集光レンズ７もその方向に同じ動きをし、光スポット
１６を矢印１４で示す方向に移動させることができる。The other reflected light split by the half mirror 9 is
The tracking position error of the light spot [6] that is incident on the two-split optical sensor 20 and directed to a tracking guide groove provided on the surface of the disk 17 (not shown) is detected. This tracking position error detection method is a conventionally well-known push-pull method, and the detected tracking position error signal is fed back to the tracking actuator 12 via a tracking control circuit (not shown). , the tracking movable part 4 is driven in the direction shown by the arrow 14 so that the optical spot 16 is located at the center of the tracking guide groove. A beam splitter 21, a prism 22.
1. Since the /4 wavelength plate and the condenser lens 7 are fixed in the direction shown by the arrow 14, when the tracking movable part 4 is moved in the direction shown by the arrow ]4 (radial direction of the disk 17), the condenser lens 7 also moves in the direction shown by the arrow ]4. With the same movement in the direction, the light spot 16 can be moved in the direction indicated by the arrow 14.

一方、半導体レーザー２からの入射光で、ビームスプリ
ンタ２１において、透過した光は、プリズム２２によっ
て直角方向に反射され、２分割光センサ１８に入射する
。こうすることによって、後に詳しく説明する如く、矢
印１４で示す方向に対するプリズム２２の位置によって
、２分割光センサ１８の２つの光センサに入射する光量
が異なり、２つの光センサ相互の差を演算することによ
ｐ２位置に比例した信号を得ることができる。言いかえ
れば、光学ヘッド１に対する集光レンズ７の矢印１４で
示す方向の位置を検出することができ１前述した如く、
集光レンズ７を光学ヘッド１の中心に位置決めすること
ができ、しかも、トラックアクセス時に、集光レンズ７
を光学ヘッド１内の一定位置に固定することができ、ト
ラックアクセス終了時の集光レンズ７の振動を抑えるこ
とができる。On the other hand, the incident light from the semiconductor laser 2 that passes through the beam splinter 21 is reflected by the prism 22 in the right angle direction and enters the two-split optical sensor 18 . By doing this, as will be explained in detail later, the amount of light incident on the two optical sensors of the two-split optical sensor 18 differs depending on the position of the prism 22 in the direction indicated by the arrow 14, and the difference between the two optical sensors is calculated. In particular, a signal proportional to the p2 position can be obtained. In other words, the position of the condenser lens 7 in the direction indicated by the arrow 14 relative to the optical head 1 can be detected.
The condensing lens 7 can be positioned at the center of the optical head 1, and the condensing lens 7 can be positioned at the center of the optical head 1.
can be fixed at a fixed position within the optical head 1, and vibration of the condenser lens 7 at the end of track access can be suppressed.

第２図（ａ）、（ｂ）は第１図のトラッキング可動部４
を拡大した図であり、集光レンズ７の光学ヘッド１に対
するトラッキング方向の位置検出をわかり易く説明する
ための図である。第２図（ａ）は、集光レンズ７が光学
ヘッド１の中心に位置している場合を示しており、同図
（ｂ）は、トラッキング可動部４が光学ヘッドＩＫ対し
て矢印３１で示す方向にずれている場合を示している。FIGS. 2(a) and 2(b) show the tracking movable part 4 of FIG.
FIG. 2 is an enlarged view for explaining position detection of the condenser lens 7 in the tracking direction with respect to the optical head 1 in an easy-to-understand manner. FIG. 2(a) shows a case where the condenser lens 7 is located at the center of the optical head 1, and FIG. 2(b) shows a case where the tracking movable part 4 is located in the optical head IK as indicated by an arrow 31. This shows a case in which there is a deviation in the direction.

同図（ａ）において、入射光３ｏはビームスプリッタ−
２１によって直角方向へ反射され、１／４波長板６、集
光レンズ７を通過して、ディスク１７の記録面上のスボ
ッ）１６に集光され、そとでの反射光は集光レンズ７．
１／４波長板６を通過して、ビームスプリッタ−２１に
よって、入射光と同一方向へ反射され、第１図で説明し
た如く、焦点位置誤差検出、トラッキング位置誤差検出
、および情報信号検出が行われる。このとき、入射光３
゜のビームスプリッタ−２１での透過光は、プリズム２
２によって直角方向に反射され、２分割光センサ１８へ
入射する。そして、集光レンズ７が光学ヘッドの中心に
位置しているため、２分割光センサ１８への入射光の光
軸は２分割光センサ１８の分割線上に位置するため、２
つの光センサの受光量は等しく々す、２つの光センサ相
互の差はゼロとなる。すなわち、位置誤差信号としては
、位置誤差がないことを示すことになる。In the same figure (a), the incident light 3o is transmitted to the beam splitter.
21 in the right angle direction, passes through the 1/4 wavelength plate 6 and the condensing lens 7, and is condensed on the recording surface of the disk 17 (16). ．．
The light passes through the quarter-wave plate 6 and is reflected by the beam splitter 21 in the same direction as the incident light, and as explained in FIG. 1, focal position error detection, tracking position error detection, and information signal detection are performed. be exposed. At this time, the incident light 3
The light transmitted through the beam splitter 21 of
2 in the right angle direction and enters the two-split optical sensor 18 . Since the condenser lens 7 is located at the center of the optical head, the optical axis of the incident light to the two-split optical sensor 18 is located on the dividing line of the two-split optical sensor 18, so
The amounts of light received by the two optical sensors are equal, and the difference between the two optical sensors is zero. In other words, the position error signal indicates that there is no position error.

一方、同図色）で示した如く、集光レンズ７が光学ヘッ
ド１の中心位置から矢印３１で示した方向にずれている
場合、プリズム２２によって反射された入射光は、２分
割光センサ１８の片方の光センサに多く入射するため、
２つの光センサ相互の差はゼロとはならず、集光レンズ
７のずれ景に比例した値を示す。逆に、図には示してい
ないが、集光レンズ７が矢印３１で示した方向とは逆方
向（９） にずれた場合には、前記した極性とは逆極性の値を示す
。On the other hand, if the condensing lens 7 is shifted from the center position of the optical head 1 in the direction indicated by the arrow 31, as shown in the same figure), the incident light reflected by the prism 22 will be transmitted to the two-split optical sensor 18. Since more light is incident on one of the optical sensors,
The difference between the two optical sensors is not zero, but shows a value proportional to the deviation of the condensing lens 7. Conversely, although not shown in the figure, if the condenser lens 7 is shifted in the direction (9) opposite to the direction indicated by the arrow 31, it will exhibit a value with a polarity opposite to that described above.

以上説明した如く、集光レンズ７とビームスプリッタ−
２１とプリズム２２とを同時にトラッキング方向に動か
し、ビームスプリッタ−２１での入射光３０の透過光を
プリズム２２で直角方向に反射し、その反射光を２分割
光センサ１８で検出することによｐ、集光レンズ７の光
学へラド１に反するトラッキング方向の位置を正確に検
出することができる。さらに、このときビームスプリッ
タ２１での透過光に対する反射光の割合いを大きくして
おけば、光学ヘッドの光利用率の低下は小さく抑えるこ
とができ、情報の記録、再生に支障を来すことはない。As explained above, the condenser lens 7 and the beam splitter
21 and prism 22 at the same time in the tracking direction, the transmitted light of the incident light 30 at the beam splitter 21 is reflected in the right angle direction by the prism 22, and the reflected light is detected by the two-split optical sensor 18. , the position of the condenser lens 7 in the tracking direction opposite to the optical radar 1 can be accurately detected. Furthermore, if the ratio of the reflected light to the transmitted light at the beam splitter 21 is increased at this time, the decrease in the light utilization efficiency of the optical head can be suppressed to a small extent, thereby preventing problems in recording and reproducing information. There isn't.

【図面の簡単な説明】[Brief explanation of drawings]

第１図は本発明による光学ヘッドの一実施例を示すブロ
ック図、第２図（ａ）、（ｂ）は第１図のトラッキング
可動部を拡大した図であり、光学ヘッドに対する集光レ
ンズの位置検出をゎかシ易く説明すｒｌｏ） るための図である。 図において、１・−°光学ヘッド、２・・・半導体レー
ザー、３・・・コリメートレンズ、４・・・トラッキン
グ可動部、５・・°偏光ビームスプリッタ、６・・・１
／４波長板、７・・・集光レンズ、８．・２３・・・反
射面、９・・・ハーフミラ−１１０・・・凸レンズ、１
１・・・ナイフェツジ、１２・・・トラッキングアクチ
ュエータ、１３・−・焦点制御用アクチュエータ％　１
６・°・光スポット）１７・・・ディスク、１８，１９
．２０・・・２分割光センサ、２１・・・ビームスプリ
ッタ、２２・・・プリズムをそれぞれ示す。 代理人弁理士　内Ｊ咀　　晋 （１１） 窒１図 第２図FIG. 1 is a block diagram showing an embodiment of the optical head according to the present invention, and FIGS. 2(a) and 2(b) are enlarged views of the tracking movable part in FIG. FIG. 2 is a diagram for easily explaining position detection. In the figure, 1...-° optical head, 2... semiconductor laser, 3... collimating lens, 4... tracking movable part, 5...° polarizing beam splitter, 6... 1
/4 wavelength plate, 7... condensing lens, 8.・23... Reflective surface, 9... Half mirror 110... Convex lens, 1
1... Naifetsuji, 12... Tracking actuator, 13... Focus control actuator% 1
6・°・light spot) 17... disk, 18, 19
．． 20: Two-split optical sensor, 21: Beam splitter, 22: Prism, respectively. Representative Patent Attorney Susumu Nai J Tsui (11) Figure 1 Figure 2

Claims (1)

【特許請求の範囲】 半導体レーザーから発光される光を集光レンズによって
記録媒体面上に集光して、情報の記録あるいは読出しを
行う光学ヘッドにおいて、前記半導体レーザーからの入
射光を直進方向と直角方向とに分けるビームスプリッタ
−と前記直角方向に分けられた光を記録媒体面上に微小
スポットに集光する集光レンズと、前記直進方向に分け
られた光を直角方向に反射するプリズムと、前記プリズ
ムによって反射された光を受ける２分割光センサとを有
し、前記ビームスプリッタ、前記集光レンズおよび前記
プリズムをディスク半径方向に同一動作を行わせ、前記
２分割光センサによって、光学ヘッドに対する前記集光
レンズのディスク半径方向の位置を検出す石ことを特徴
とする光学ヘラ（１） ド。[Scope of Claims] In an optical head that records or reads information by condensing light emitted from a semiconductor laser onto the surface of a recording medium using a condensing lens, the incident light from the semiconductor laser is directed in a straight direction. a beam splitter that separates the beam into a perpendicular direction, a condenser lens that focuses the beam split in the perpendicular direction onto a minute spot on the recording medium surface, and a prism that reflects the beam split in the rectilinear direction in the perpendicular direction. and a two-split optical sensor that receives the light reflected by the prism, and causes the beam splitter, the condenser lens, and the prism to perform the same operation in the disk radial direction, and the optical head is controlled by the two-split optical sensor. An optical spatula (1) characterized in that it includes a stone for detecting the position of the condensing lens in the disk radial direction relative to the disk.
JP57180250A 1982-06-14 1982-10-14 Optical head Granted JPS5971138A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
JP57180250A JPS5971138A (en) 1982-10-14 1982-10-14 Optical head
EP83303435A EP0098076A1 (en) 1982-06-14 1983-06-14 Beam access apparatus for optical disc system
US06/765,172 US4615023A (en) 1982-06-14 1985-08-12 Beam access apparatus for optical disc system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP57180250A JPS5971138A (en) 1982-10-14 1982-10-14 Optical head

Publications (2)

Publication Number Publication Date
JPS5971138A true JPS5971138A (en) 1984-04-21
JPS6310490B2 JPS6310490B2 (en) 1988-03-07

Family

ID=16079981

Family Applications (1)

Application Number Title Priority Date Filing Date
JP57180250A Granted JPS5971138A (en) 1982-06-14 1982-10-14 Optical head

Country Status (1)

Country Link
JP (1) JPS5971138A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4955010A (en) * 1985-07-18 1990-09-04 Kabushiki Kaisha Toshiba Constant velocity track jump servo system for disc players

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4955010A (en) * 1985-07-18 1990-09-04 Kabushiki Kaisha Toshiba Constant velocity track jump servo system for disc players

Also Published As

Publication number Publication date
JPS6310490B2 (en) 1988-03-07

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