JPS6139942A - Optical pickup - Google Patents

Optical pickup

Info

Publication number
JPS6139942A
JPS6139942A JP16187684A JP16187684A JPS6139942A JP S6139942 A JPS6139942 A JP S6139942A JP 16187684 A JP16187684 A JP 16187684A JP 16187684 A JP16187684 A JP 16187684A JP S6139942 A JPS6139942 A JP S6139942A
Authority
JP
Japan
Prior art keywords
disk
information track
half mirror
semiconductor laser
optical path
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
JP16187684A
Other languages
Japanese (ja)
Other versions
JPH058499B2 (en
Inventor
Hiroyuki Nakamura
裕行 中村
Masayuki Ito
正之 伊藤
Toshiki Matsuno
松野　俊樹
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.)
Panasonic Holdings Corp
Original Assignee
Matsushita Electric Industrial 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 Matsushita Electric Industrial Co Ltd filed Critical Matsushita Electric Industrial Co Ltd
Priority to JP16187684A priority Critical patent/JPS6139942A/en
Publication of JPS6139942A publication Critical patent/JPS6139942A/en
Publication of JPH058499B2 publication Critical patent/JPH058499B2/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
    • G11B7/0908—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 focusing 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
    • G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam

Abstract

PURPOSE:To obtain an inexpensive and simple device by tilting an optical path from a semiconductor laser to a half mirror to an information track of a disk by 45 deg.. CONSTITUTION:The optical path from the semiconductor laser 8 to the half mirror 9 is tilted by 45 deg. to the information track 11 of the disc 1, thereby directing the astigmatism on a photodetector 5 to the direction 12 of the map of the information track by 45 deg.. Since the direction of major axis of an elliptic converging spot on the disc 1 is made orthogonal to the information track 11 in this case, it is required to match the polarized direction of the semiconductor laser 8 in the direction of arrow in the figure. Thus, the half mirror 9 is used.

Description

【発明の詳細な説明】 産業上の利用分野 本発明に、ディスクに高密度なデジタル信号を記録させ
た情報トラックに光スポットを投影させて光学的に情報
を読み取る光ピツクアップに関するものである。DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical pickup that optically reads information by projecting a light spot onto an information track on which a high-density digital signal is recorded on a disk.

従来例の構成とその問題点 レーザーから出た光を対物レンズによってディスク上に
収束させる際に生じるフォーカス誤差を検出する方法と
して、非点収差法が従来から最も一般的に用いられてい
る。Conventional configuration and its problems The astigmatism method has conventionally been most commonly used as a method for detecting a focus error that occurs when light emitted from a laser is focused onto a disk by an objective lens.

これに第１図に示すように、ディスク１からの記録情報
を受光素子６に導く光路上に、凸レンズ３と円筒レンズ
４を配し、ディスク１と対物レンズ２の相対的な位置関
係に応じて、受光素子５上に非点収差を発生させる方式
であり、具体的にげ第２図に示すように、ディスク１と
対物レンズ２が近すぎる場合（ａ）、焦点位置にるる場
合（ｂ）。As shown in FIG. 1, a convex lens 3 and a cylindrical lens 4 are disposed on the optical path that guides recorded information from the disk 1 to the light receiving element 6, and the lens 4 corresponds to the relative positional relationship between the disk 1 and the objective lens 2. This method generates astigmatism on the light-receiving element 5. Specifically, as shown in FIG. ).

遠すぎる場合（Ｃ）、のそれぞれについて、受光素子６
上のスポット形状が図に示したようになり、（５ａ−１
−５ｂ　）−（ｓｃ＋６ｄ　）を求めることによってフ
ォーカス誤差を検出できるというものである。For each case (C) when it is too far away, the light receiving element 6
The upper spot shape becomes as shown in the figure, (5a-1
-5b)-(sc+6d), the focus error can be detected.

第３図σ第１図よりもざらに簡単な構成で非点収差を発
生させる例であり、ディスク１からの反射光が平行平板
でできたハーフミラ−９を透過することによって受光素
子６上に非点収差を発生させるものでめる。（矢印にト
ラック方向）この時、フォーカスレンズ２の移動による
フォーカス誤差を避ける目的と、反射光のファーフィー
ルドパターンを利用してトラッキング誤差検出を行なう
ため、通常、受光素子６上で、ディスクの情報トラック
の写像が受光素子５の分割線と同方向になるよう、すな
わち、非点収差の方向に対して４５°になるように構成
する。Fig. 3 σ This is an example of generating astigmatism with a simpler configuration than that shown in Fig. 1, in which the reflected light from the disk 1 passes through the half mirror 9 made of a parallel flat plate and is reflected onto the light receiving element 6. It is defined as something that causes astigmatism. (The arrow indicates the track direction.) At this time, in order to avoid focus errors due to movement of the focus lens 2 and to detect tracking errors using the far field pattern of reflected light, the disc information is normally displayed on the light receiving element 6. It is configured so that the mapping of the track is in the same direction as the dividing line of the light receiving element 5, that is, at 45° with respect to the direction of astigmatism.

従来、この方法として第４図に示すように、平行平板の
ハーフミラ−の代わりにくさび状のハーフミラ−１０を
用い、角度αを適当に選択することによって非点収差の
方向をディスクの情報トラックの写像に対して４５°に
することが提案はれてきた。Conventionally, as shown in FIG. 4, this method uses a wedge-shaped half mirror 10 instead of a parallel plate half mirror, and by appropriately selecting the angle α, the direction of the astigmatism is adjusted to the information track of the disk. It has been proposed to make the angle 45° with respect to the mapping.

しかし、平行平板のハーフミラ−が一度に大量生産でき
るのに対して、くさび状のノ・−フミラーに一度に少量
しか生産できないはかシか、研磨コストも高くなり、光
ピツクアップとして、コストアップの要因となっていた
。However, while parallel plate half mirrors can be mass-produced at one time, wedge-shaped no-fah mirrors can only be produced in small quantities at a time, and polishing costs are also high. This was a contributing factor.

発明の目的 本発明に上記のような問題点を解決するもので、低コス
トの光ピノクア・フプを提供するものである。OBJECTS OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide a low-cost optical pinocqua.

発明の構成 本発明に半導体レーザーからノ・−フミラーに至る光路
をディスクの情報トラックに対して４５゜傾斜させるこ
とによって、受光素子上で非点収差の方向がディスクの
情報トラックの写像の方向に対して４５°になるように
するもので、光ピツクアップの低コスト化を実現するも
のである。Structure of the Invention In the present invention, by tilting the optical path from the semiconductor laser to the nof mirror at 45 degrees with respect to the information track of the disk, the direction of astigmatism on the light receiving element is aligned with the direction of mapping of the information track of the disk. This makes it possible to reduce the cost of optical pickup.

実施例の説明 第５図は本発明の一実施例を示したものであり、第６図
に第５図をディスク１の上方から見た図である（但し、
対物レンズ２に省略している）。第６図かられかるよう
に、半導体レーザー８からノ・−７ミラー９ＶＣ至る光
路にディスク１の情報トラック１１に対して４５°傾斜
しており、これによって、受光素子ε上で非点収差の方
向を情報トラックの写像の方向１２に対して４５°にす
ることができる。この時、ディスク１上での楕円形状の
収束スポットの長軸方向を情報トラック１１と直角方向
にするため、半導体レーザー８の偏光方向を第６図にお
いて矢印の方向に合わせる必要がるる。このため、９に
偏光ビームスプリッタ（偏光ビームスプリッタを使う時
に、猛波長板が必要）でなく、ハーフミラ−であること
が望ましい。DESCRIPTION OF EMBODIMENTS FIG. 5 shows an embodiment of the present invention, and FIG. 6 is a view of FIG. 5 viewed from above the disk 1 (however,
(omitted from objective lens 2). As can be seen from FIG. 6, the optical path from the semiconductor laser 8 to the -7 mirror 9VC is inclined at 45 degrees with respect to the information track 11 of the disk 1, and this prevents astigmatism on the light receiving element ε. The direction may be 45° to the direction 12 of the mapping of the information track. At this time, in order to make the long axis direction of the elliptical focused spot on the disk 1 perpendicular to the information track 11, it is necessary to align the polarization direction of the semiconductor laser 8 in the direction of the arrow in FIG. For this reason, it is desirable that the polarizing beam splitter 9 be a half mirror instead of a polarizing beam splitter (when using a polarizing beam splitter, a long wavelength plate is required).

第７図に薄型化のためミラー１３を使って光路を折シ曲
けた例であるが、側面図第８図かられかるように、半導
体レーザー８からハーフミラ−９に至る光路をディスク
１に対して垂直な面内で情報トラック方向（矢印）に対
して４５°傾斜させても同様の効果が得られる。また、
第６図、第７図の光学系をディスク１に垂直な軸回りに
９０．０毎に回転させても同様の効果が得られること汀
いうまでもない。FIG. 7 shows an example in which the optical path is bent using a mirror 13 to reduce the thickness of the disk.As can be seen from the side view of FIG. A similar effect can be obtained by tilting the information track direction (arrow) by 45° in a plane perpendicular to the information track direction. Also,
It goes without saying that the same effect can be obtained even if the optical system shown in FIGS. 6 and 7 is rotated every 90.0 degrees around an axis perpendicular to the disk 1.

以上のように本実施例でにくさび状のハーフミラ−を用
いず、平行平板のハーフミラ−で非点収差方向を情報ト
ラックの写像方向に対して４５゜にすることができ、光
ピツクアップのコストを安くすることができる。As described above, in this embodiment, the astigmatism direction can be set at 45 degrees with respect to the information track mapping direction by using a parallel plate half mirror without using a wedge-shaped half mirror, and the cost of optical pickup can be reduced. It can be done cheaply.

発明の効果 以上のように本発明は、半導体レーザーからハーフミラ
−に至る光路をディスクの情報トラックに対して４５°
傾斜きせることにより、半導体レ−ｆ−ｔ　平行平板ハ
ーフミラ−、フォーカスレンズ、受光素子のみで光学系
を構成することができ、非常に安価で簡素な光ピツクア
ップを提供することができる。Effects of the Invention As described above, the present invention allows the optical path from the semiconductor laser to the half mirror to be set at 45 degrees with respect to the information track of the disk.
By increasing the inclination, it is possible to construct an optical system using only a semiconductor beam parallel plate half mirror, a focus lens, and a light receiving element, and it is possible to provide a very inexpensive and simple optical pickup.

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

第１図に従来例の側面図、第２図に非点収差法の原理図
、第３図、第４図に従来例の側面図、第６図、第７図ａ
本発明の一実施例の斜視図、第６図は本発明の一実施例
の平面図、第８図に本発明の一実施例の側面図である。 １・・・・・・ディスク、２・・・・・・フォーカスレ
ンズ、３・・・・・・凸レンズ、４・・・・・・円筒レ
ンズ、５・・・・・・受光素子、６・・・・・・ハーフ
ミラ−１７・・・・・・コリメートレンズ、８・・・・
・・半導体レーザー、９・・・・・・平行平板ノ・−フ
ミラー、１ｏ・・・・・・くさび状ハーフミラ−１１１
・・・・・・情報トラック、１２・・・・・・情報トラ
ック写像方向、１３・・・・ベラ−０ 代理人の氏名　弁理士　中　尾　敏　男　ほか１名第１
図 ！ 第２図 第３図　　　　　第４図 第５図 第６図　　　　　第７図 第８図 ！Figure 1 is a side view of the conventional example, Figure 2 is a diagram of the principle of the astigmatism method, Figures 3 and 4 are side views of the conventional example, Figures 6 and 7 a.
FIG. 6 is a perspective view of one embodiment of the present invention, FIG. 6 is a plan view of one embodiment of the present invention, and FIG. 8 is a side view of one embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Disc, 2... Focus lens, 3... Convex lens, 4... Cylindrical lens, 5... Light receiving element, 6... ...Half mirror 17...Collimating lens, 8...
... Semiconductor laser, 9 ... Parallel flat plate no-f mirror, 1o ... Wedge-shaped half mirror 111
...Information track, 12...Information track mapping direction, 13...Vera-0 Name of agent Patent attorney Toshio Nakao and 1 other person 1st
figure! Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8!

Claims (1)

【特許請求の範囲】[Claims] 半導体レーザーからディスクに至る光路と、ディスクか
ら受光素子に至る光路を分離するための平行平板ででき
たハーフミラーを有し、ディスクからの反射光が前記ハ
ーフミラーを透過することによってフォーカス誤差検出
のための非点収差を発生し、かつ、受光素子上で、非点
収差の方向がディスクの情報トラックの写像の方向に対
して４５°になるように、半導体レーザーからハーフミ
ラーに至る光路をディスクの情報トラックに対して、４
５°傾斜させたことを特徴とする光ピックアップ。It has a half mirror made of a parallel flat plate to separate the optical path from the semiconductor laser to the disk and the optical path from the disk to the light receiving element, and the reflected light from the disk passes through the half mirror to detect focus errors. The optical path from the semiconductor laser to the half mirror is arranged on the disk so that the direction of the astigmatism is 45 degrees to the direction of mapping of the information track of the disk on the light receiving element information track, 4
An optical pickup characterized by being tilted at 5 degrees.
JP16187684A 1984-08-01 1984-08-01 Optical pickup Granted JPS6139942A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP16187684A JPS6139942A (en) 1984-08-01 1984-08-01 Optical pickup

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP16187684A JPS6139942A (en) 1984-08-01 1984-08-01 Optical pickup

Publications (2)

Publication Number Publication Date
JPS6139942A true JPS6139942A (en) 1986-02-26
JPH058499B2 JPH058499B2 (en) 1993-02-02

Family

ID=15743654

Family Applications (1)

Application Number Title Priority Date Filing Date
JP16187684A Granted JPS6139942A (en) 1984-08-01 1984-08-01 Optical pickup

Country Status (1)

Country Link
JP (1) JPS6139942A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6310326A (en) * 1986-07-01 1988-01-16 Sanyo Electric Co Ltd Optical pickup device
JPH0220819U (en) * 1988-07-27 1990-02-13

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5337722A (en) * 1976-09-20 1978-04-07 Ebata Shiyouji Kk Method of producing concrete piles
JPS53117403A (en) * 1977-03-22 1978-10-13 Philips Nv Reflection type record carrier reader
JPS5657013A (en) * 1979-09-28 1981-05-19 Philips Nv Focus error detector

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5337722A (en) * 1976-09-20 1978-04-07 Ebata Shiyouji Kk Method of producing concrete piles
JPS53117403A (en) * 1977-03-22 1978-10-13 Philips Nv Reflection type record carrier reader
JPS5657013A (en) * 1979-09-28 1981-05-19 Philips Nv Focus error detector

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6310326A (en) * 1986-07-01 1988-01-16 Sanyo Electric Co Ltd Optical pickup device
JPH0220819U (en) * 1988-07-27 1990-02-13
JPH064412Y2 (en) * 1988-07-27 1994-02-02 パイオニア株式会社 Optical pickup device

Also Published As

Publication number Publication date
JPH058499B2 (en) 1993-02-02

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