JPS6367256B2 - - Google Patents
Info
- Publication number
- JPS6367256B2 JPS6367256B2 JP5712681A JP5712681A JPS6367256B2 JP S6367256 B2 JPS6367256 B2 JP S6367256B2 JP 5712681 A JP5712681 A JP 5712681A JP 5712681 A JP5712681 A JP 5712681A JP S6367256 B2 JPS6367256 B2 JP S6367256B2
- Authority
- JP
- Japan
- Prior art keywords
- recording
- recording layer
- laser
- irradiation means
- laser beam
- 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
Links
- 230000003287 optical effect Effects 0.000 claims description 26
- 230000003247 decreasing effect Effects 0.000 claims 1
- 230000035945 sensitivity Effects 0.000 description 5
- 238000000926 separation method Methods 0.000 description 5
- 238000000034 method Methods 0.000 description 3
- 238000004804 winding Methods 0.000 description 3
- PPBRXRYQALVLMV-UHFFFAOYSA-N Styrene Chemical compound C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 239000004925 Acrylic resin Substances 0.000 description 1
- 229920000178 Acrylic resin Polymers 0.000 description 1
- 239000000020 Nitrocellulose Substances 0.000 description 1
- 239000004677 Nylon Substances 0.000 description 1
- 239000006096 absorbing agent Substances 0.000 description 1
- 229920000122 acrylonitrile butadiene styrene Polymers 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005553 drilling Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 229940093920 gynecological arsenic compound Drugs 0.000 description 1
- 230000001678 irradiating effect Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229920001220 nitrocellulos Polymers 0.000 description 1
- 229920001778 nylon Polymers 0.000 description 1
- 230000010287 polarization Effects 0.000 description 1
- 229920003217 poly(methylsilsesquioxane) Polymers 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 229920003002 synthetic resin Polymers 0.000 description 1
- 239000000057 synthetic resin Substances 0.000 description 1
- 229910052714 tellurium Inorganic materials 0.000 description 1
- PORWMNRCUJJQNO-UHFFFAOYSA-N tellurium atom Chemical compound [Te] PORWMNRCUJJQNO-UHFFFAOYSA-N 0.000 description 1
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
- G11B7/004—Recording, reproducing or erasing methods; Read, write or erase circuits therefor
- G11B7/0055—Erasing
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
- G02B7/28—Systems for automatic generation of focusing signals
- G02B7/30—Systems for automatic generation of focusing signals using parallactic triangle with a base line
- G02B7/32—Systems for automatic generation of focusing signals using parallactic triangle with a base line using active means, e.g. light emitter
-
- 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
- G11B7/08—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
- G11B7/0917—Focus-error methods other than those covered by G11B7/0909 - G11B7/0916
-
- 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
- G11B7/0917—Focus-error methods other than those covered by G11B7/0909 - G11B7/0916
- G11B2007/0924—Skewed beams methods (using an angled beam, i.e. a beam which is reflected from the disc at an angle different from 90°)
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Automatic Focus Adjustment (AREA)
- Optical Recording Or Reproduction (AREA)
Description
【発明の詳細な説明】 本発明は光記録系の焦点制御装置に関する。[Detailed description of the invention] The present invention relates to a focus control device for an optical recording system.
光記録系においては、光記録媒体がデイスクで
あれば回転させ、またテープであれば走行させな
がら、情報の記録や再生を行なうが、通常これら
の回転や走行に伴なつて記録層には面ブレを生ず
るので、この面ブレに対してもレーザビームを集
光レンズにより集束した焦点が記録層に常に合致
するように、焦点制御が行われる。 In an optical recording system, information is recorded and reproduced by rotating the optical recording medium in the case of a disk or running it in the case of a tape. Since this causes blurring, focus control is performed so that the focal point of the laser beam focused by the condensing lens always matches the recording layer even with this surface blurring.
従来行われている焦点制御方法として、記録・
再生用のレーザビームを同時に焦点制御用レーザ
ビームとして用いる方法があるが、記録時には記
録層上に孔をあけながら同時に焦点制御を行な
い、また再生時には情報として孔を形成された記
録層にレーザビームを照射し、孔の部分の乱反射
による反射ビームの明暗から記録情報を再生しな
がら、これも同時に焦点制御を行なつている。従
つて記録・再生のいずれの場合にも焦点制御用レ
ーザビームを孔をあけつつある、または孔の既に
あいている記録層で反射する反射ビームから得て
いるため、焦点制御用レーザビームとしては孔に
よる乱反射の影響を受けるのでＳ／Ｎ比が悪く、
精度の良い焦点制御ができにくいという欠点があ
つた。また情報の記録においても、記録層への孔
の形成を１個のレーザビームにより一時に行なつ
ているため、レーザビームには大きなパワーが必
要であり、かつ記録層としても感度の良いものが
必要であるという欠点があつた。 The conventional focus control method is recording and
There is a method of using a laser beam for reproduction as a laser beam for focus control at the same time, but during recording, a hole is made on the recording layer and focus control is performed at the same time, and during reproduction, the laser beam is used as information on the recording layer with the hole formed. The recorded information is reproduced from the brightness of the reflected beam due to diffuse reflection from the hole, and the focus is controlled at the same time. Therefore, in both recording and reproduction, the focus control laser beam is obtained from the reflected beam reflected from the recording layer that is drilling holes or has already formed holes, so the focus control laser beam is The S/N ratio is poor because it is affected by diffused reflection from the holes.
The drawback was that it was difficult to perform accurate focus control. In addition, when recording information, holes are formed in the recording layer at once using a single laser beam, so the laser beam requires a large power, and the recording layer must also be sensitive. It had the disadvantage of being necessary.
本発明の目的は、このような従来の光記録系の
焦点制御装置の有する欠点を解消することにあ
り、焦点制御用信号のＳ／Ｎ比を大きくすること
によつて焦点制御を精度よく行ない、併せて記
録・再生用のレーザビームをパワーの小さいもの
でもよいものにし、また記録層も感度の悪いもの
でも使用できるようにするものである。 An object of the present invention is to eliminate the drawbacks of the conventional focus control device for an optical recording system, and to perform focus control with high accuracy by increasing the S/N ratio of the focus control signal. In addition, the laser beam for recording and reproducing can be used with low power, and the recording layer can also be used with a low sensitivity.
そこで本発明は、第１のレーザによる記録・再
生用の第１の照射手段に加えて、第２のレーザに
よる焦点制御用の第２の照射手段を設け、この第
２の照射手段による制御用ビームを第１の照射手
段の集光レンズの光軸を外れたところを通過させ
ると共に、その焦点を、走行しつつある記録媒体
の記録層の第１の照射手段による記録または再生
のための焦点よりも走行方向前位側に結ばせて、
この反射ビームを焦点制御用ビームとし、孔のな
い平担な記録層で反射される反射ビームを利用し
てＳ／Ｎ比の大きな制御用ビームを得ることによ
り焦点制御を精度良く行ない、併せて記録時には
この第２照射手段により記録層を予熱することに
よつて記録層の感度を高め、記録用の第１照射手
段のレーザをパワーの小さいものでよいものに
し、さらに感度のあまり良くない記録層に対して
も小さいパワーのレーザで記録できるようにする
ものである。 Therefore, in the present invention, in addition to the first irradiation means for recording/reproducing using the first laser, a second irradiation means for controlling the focus using the second laser is provided, and the second irradiation means for controlling the focus by the second laser is provided. The beam is caused to pass through a point off the optical axis of the condensing lens of the first irradiation means, and its focus is set as a focal point for recording or reproduction by the first irradiation means on the recording layer of the recording medium that is traveling. Tie it to the front side in the running direction,
This reflected beam is used as a focus control beam, and by using the reflected beam reflected by a flat recording layer without holes to obtain a control beam with a large S/N ratio, focus control can be performed with high precision. At the time of recording, the sensitivity of the recording layer is increased by preheating the recording layer using this second irradiation means, and the first irradiation means for recording can be used with a low-power laser, and furthermore, the sensitivity of the recording layer is not very good. This makes it possible to record even layers using a laser with low power.
また本出願人は、光記録媒体の記録層として、
その出現が大きく望まれていた消去可能（すなわ
ち、記録再生に加えて記録された情報の消去およ
び再記録が可能）な記録媒体を開発し、これを別
途出願した（昭和56年４月７日特許出願(1)、発明
の名称「光記録媒体」）。この消去可能な記録媒体
の詳細は同上特許出願明細書に譲るが、ここで簡
単に説明すると、記録層をスチレン低重合化合
物、ナイロンまたはABS樹脂などの熱融解性合
成樹脂で構成し、基体としてはガラスまたはアク
リル樹脂のどちらか一方で構成するものである。
このような消去可能な記録媒体を用いた場合は、
記録時は記録情報に対応した細いレーザビームを
照射して記録層を選択的に融解させることにより
凹状の孔を形成し、再生時には弱いレーザビーム
を照射して孔の部分で乱反射が起こり反射ビーム
に記録された孔の有無に応じて明暗を含む現象を
利用して行われ、そして情報の消去は孔の直径に
比べて十分に太くかつ強いレーザビームを照射し
て孔の周囲を融解させて孔を消滅させることによ
り行われ、孔を消滅させた領域では、再び情報を
記録することが可能である。 In addition, the applicant has proposed that as a recording layer of an optical recording medium,
We developed an erasable recording medium (that is, it is possible to erase and re-record recorded information in addition to recording and reproducing), and filed a separate application for this (April 7, 1982). Patent application (1), title of invention "Optical recording medium"). The details of this erasable recording medium are given in the above patent application specification, but to briefly explain it here, the recording layer is composed of a heat-melting synthetic resin such as a styrene low polymer compound, nylon or ABS resin, and the base material is is made of either glass or acrylic resin.
When using such an erasable recording medium,
During recording, a narrow laser beam corresponding to the recorded information is irradiated to selectively melt the recording layer to form a concave hole, and during playback, a weak laser beam is irradiated and diffuse reflection occurs at the hole, resulting in a reflected beam. The information is erased by using a phenomenon that includes brightness and darkness depending on the presence or absence of holes recorded in the hole, and information is erased by irradiating a laser beam that is sufficiently thick and strong compared to the diameter of the hole to melt the area around the hole. This is done by eliminating holes, and information can be recorded again in the area where the holes have been eliminated.
本発明は、従来の例えばテルル、テルル−セレ
ン−ヒ素の化合物、あるいはニトロセルロースと
光吸収剤の混合物などの消去できない光記録媒体
の焦点制御や予熱に対して有効であると共に、上
述したような消去可能な光記録媒体に対しても、
第２照射手段による制御用レーザビームを焦点制
御や予熱に加えて記録情報の消去用として用いる
ことができるものである。 The present invention is effective for focus control and preheating of conventional non-erasable optical recording media such as tellurium, tellurium-selenium-arsenic compounds, or mixtures of nitrocellulose and light absorbers, as well as for the above-mentioned methods. Even for erasable optical recording media,
The control laser beam by the second irradiation means can be used not only for focus control and preheating but also for erasing recorded information.
以下実施例につき、図面を参照して以下に説明
する。 Examples will be described below with reference to the drawings.
図において、１は第１のレーザで例えばHeNe
レーザを用いる。２はコリメータレンズでレーザ
ビームを平行ビームにし、３は光変調器で記録情
報に従つてレーザビームを強度変調する。４はビ
ームスプリツタで、主軸方向に振動するレーザビ
ームは通過させるが、これと直角方向に振動する
レーザビームは通さず、直線偏光を生じさせる。
５は1/4波長板で第１のレーザ１の波長に応じて
適当なものを使用し、この1/4波長板５は円偏光
を得るもので、これを通過したレーザビームは円
偏波となる。６はダイクロミツクミラーで波長選
択性を有し、設定された波長のレーザビームは通
過させずに反射させるが、それ以外の波長のレー
ザビームは通過させる。本実施例においては第１
のレーザ１からのレーザビームは通過させる。７
は焦光レンズ、８は記録媒体の記録層で、この記
録媒体の走行方向を仮に矢印Ａで示す。９はフオ
トデイテクタで、ビームスプリツタ４で分離反射
されてくる反射ビームを受光し、受光量に応じた
電気信号を出力し、この出力信号は再生信号とし
て使用される。以上で第１の照射手段が構成され
る。 In the figure, 1 is the first laser, for example HeNe
Uses a laser. A collimator lens 2 converts the laser beam into a parallel beam, and an optical modulator 3 modulates the intensity of the laser beam according to recorded information. Reference numeral 4 denotes a beam splitter, which allows a laser beam vibrating in the direction of the principal axis to pass through, but not a laser beam vibrating in a direction perpendicular to the principal axis, producing linearly polarized light.
Reference numeral 5 denotes a 1/4 wavelength plate, which is appropriate depending on the wavelength of the first laser 1. This 1/4 wavelength plate 5 obtains circularly polarized light, and the laser beam that passes through it is circularly polarized. becomes. Reference numeral 6 denotes a dichromic mirror which has wavelength selectivity and reflects a laser beam of a set wavelength without passing through, but allows laser beams of other wavelengths to pass. In this example, the first
The laser beam from the laser 1 is allowed to pass through. 7
8 is a focusing lens, 8 is a recording layer of a recording medium, and the running direction of this recording medium is tentatively shown by arrow A. A photodetector 9 receives the reflected beam separated and reflected by the beam splitter 4, outputs an electric signal corresponding to the amount of received light, and this output signal is used as a reproduction signal. The first irradiation means is thus configured.
また１０は第２のレーザで例えば発光ダイオー
ドレーザ（LED）などのコヒーレンシはあまり
良くなくても、パワーの大きなレーザが好まし
い。１１はコリメータレンズ、１２はビームスプ
リツタ、１３は1/4波長板で第２のレーザ１０の
波長に応じて選定される。また前述したダイクロ
ミツクミラー６は、この第２のレーザ１０による
レーザビームに対しては反射させるように設定さ
れる。第２のレーザ１０からのレーザビームはダ
イクロミツクミラー６を通過した後、集光レンズ
７の光軸を外れた部分を通され、かつ記録層８の
前記第１の照射手段による焦点Ｂよりも記録媒体
の走行方向前位側に焦点Ｃが結ばれるように光学
系が設定される。なおこの両焦点ＢとＣの間隔
は、光学系の設計により任意に設定できる。１４
は２分割フオトダイオードで分離点１４ａを境に
２個のフオトダイオード１４ｂ，１４ｃを接合し
て構成され、その分離点１４ａのビームスプリツ
タ１２との相対位置は、走行中の記録層８の位置
が丁度集光レンズ７の焦点Ｂに合致している時
（この時焦点ＢとＣは近いので、記録層８は焦点
Ｃとも合致する）に、第２のレーザ１０からの入
射ビームがこの記録層８上で反射し、この反射ビ
ームが集光レンズ７のさらに光軸を外れた部分を
通過し、ダイクロミツクミラー６で反射され、ビ
ームスプリツタ１２で分離反射して２分割フオト
ダイオード１４を照射した際に、その反射ビーム
の中心と分離点１４ａとが合致するように、予め
関係位置を設定しておく。２つのフオトダイオー
ド１４ｂ，１４ｃはそれぞれが受光した受光量に
応じて電気信号を出力し、この出力信号は差動増
幅器（図示しない）により差をとられて増幅され
る。１５は巻線で、上記焦点制御用信号により励
磁され、集光レンズ７の位置を調節して焦点を記
録層８上に合致させる。そして以上で第２の照射
手段を構成する。 Further, 10 is a second laser, which is preferably a light-emitting diode laser (LED), which has a high power even if the coherency is not very good. 11 is a collimator lens, 12 is a beam splitter, and 13 is a 1/4 wavelength plate, which are selected according to the wavelength of the second laser 10. Further, the dichroic mirror 6 described above is set to reflect the laser beam from the second laser 10. After passing through the dichroic mirror 6, the laser beam from the second laser 10 is passed through a portion of the condensing lens 7 that is off the optical axis, and is further away from the focal point B of the recording layer 8 by the first irradiation means. The optical system is set so that the focal point C is on the front side in the running direction of the recording medium. Note that the distance between the two focal points B and C can be arbitrarily set depending on the design of the optical system. 14
is a two-split photodiode, which is constructed by joining two photodiodes 14b and 14c with a separation point 14a as a boundary, and the relative position of the separation point 14a with respect to the beam splitter 12 is the position of the recording layer 8 during travel. coincides with the focal point B of the condensing lens 7 (at this time, the focal points B and C are close, so the recording layer 8 also coincides with the focal point C), the incident beam from the second laser 10 focuses on this recording layer. The reflected beam is reflected on the layer 8, passes through a part of the condensing lens 7 further off the optical axis, is reflected by the dichromic mirror 6, and is separated and reflected by the beam splitter 12 to be split into two photodiodes 14. The relative positions are set in advance so that the center of the reflected beam coincides with the separation point 14a when irradiated. The two photodiodes 14b and 14c each output an electric signal according to the amount of light received, and the difference between these output signals is taken and amplified by a differential amplifier (not shown). A winding 15 is excited by the focus control signal to adjust the position of the condensing lens 7 and bring the focus onto the recording layer 8 . The above constitutes the second irradiation means.
次に動作を説明する。 Next, the operation will be explained.
記録、再生および消去のいずれの場合も焦点制
御は第２の照射手段により行われる。すなわち、
第２のレーザ１０からのレーザビームはコリメー
タレンズ１１により平行ビームになり、ビームス
プリツタ１２によつて直線偏向され、1/4波長板
１３により円偏波とされ、ダイクロミツクミラー
６で反射されて集光レンズ７の光軸を外れた部分
を通過し、記録層８上において焦点Ｃ上に集束す
る。この入射ビームは記録層８で反射され、反射
ビームは集光レンズ７の入射ビームよりさらに光
軸を外れた部分を通り、ダイクロミツクミラー６
により反射され、1/4波長板１３で円偏波から入
射ビームの偏波方向とは直角な直線偏波に変換さ
れ、ビームスプリツタ１２により入射ビームと分
離反射され、２分割フオトダイオード１４により
受光され、それぞれのフオトダイオード１４ｂ，
１４ｃにおいてそれぞれについて受光された受光
量に応じて電気信号に変換される。 Focus control is performed by the second irradiation means in all cases of recording, reproduction, and erasing. That is,
The laser beam from the second laser 10 is turned into a parallel beam by the collimator lens 11, linearly polarized by the beam splitter 12, circularly polarized by the quarter-wave plate 13, and reflected by the dichroic mirror 6. The light passes through a portion off the optical axis of the condenser lens 7 and is focused on the focal point C on the recording layer 8 . This incident beam is reflected by the recording layer 8, and the reflected beam passes through a part further off the optical axis of the condenser lens 7 than the incident beam, and passes through the dichroic mirror 6.
The quarter-wave plate 13 converts the circularly polarized wave into a linearly polarized wave perpendicular to the polarization direction of the incident beam, the beam splitter 12 separates it from the incident beam, and the two-split photodiode 14 separates it from the incident beam. The light is received by each photodiode 14b,
At step 14c, each light is converted into an electrical signal according to the amount of light received.
走行中の記録媒体に面ブレが生じ、例えば記録
層８の位置が集光レンズ８の焦点Ｂ（従つて焦点
Ｃ）よりも遠ざかつた場合には、記録層８上の第
２のレーザビームの反射ビームは集光レンズ７の
さらに光軸を外れた部分を通過するために、球面
収差により余計大きく屈折し、反射ビームの中心
は２分割フオトダイオード１４上では分離点１４
ａよりも一方（図面上上方）のフオトダイオード
１４ｂ側に移動し、従つて上方のフオトダイオー
ド１４ｂの受光量が多くなり、かつ他方（下方）
のフオトダイオード１４ｃの受光量が少なくな
る。逆に記録層８の位置が焦点Ｂよりも近づいた
場合には、一方（上方）のフオトダイオード１４
ｂの受光量が少なくなりかつ他方（下方）のフオ
トダイオード１４ｃの受光量が多くなる。従つて
この２つのフオトダイオード１４ｂ，１４ｃでそ
れぞれ受光量に応じて変換される電気信号を差動
増幅器で差をとつて増幅すれば、記録層８の焦点
からのズレの向きと大きさに応じた焦点制御用信
号を得ることができる。この焦点制御用信号によ
り巻線１５を励磁することにより集光レンズ７の
位置が調節され、走行中に記録媒体が面ブレして
も、焦点Ｂ，Ｃが記録層８上に結ばれることにな
る。 If surface wobbling occurs in the running recording medium and, for example, the position of the recording layer 8 moves farther than the focal point B (therefore the focal point C) of the condensing lens 8, the second laser beam on the recording layer 8 Since the reflected beam passes through a part of the condensing lens 7 that is further off the optical axis, it is refracted even more due to spherical aberration, and the center of the reflected beam is at the separation point 14 on the two-split photodiode 14.
A moves toward one photodiode 14b (upper side in the drawing), so the amount of light received by the upper photodiode 14b increases, and the other photodiode 14b (lower side)
The amount of light received by the photodiode 14c decreases. Conversely, when the position of the recording layer 8 is closer than the focal point B, one (upper) photodiode 14
The amount of light received by the photodiode b decreases, and the amount of light received by the other (lower) photodiode 14c increases. Therefore, if the electric signals converted by the two photodiodes 14b and 14c according to the amount of light received are amplified by using a differential amplifier, the difference can be amplified depending on the direction and magnitude of the deviation from the focal point of the recording layer 8. It is possible to obtain a focused focus control signal. By exciting the winding 15 with this focus control signal, the position of the condenser lens 7 is adjusted, and even if the surface of the recording medium is shaken during running, the focal points B and C are fixed on the recording layer 8. Become.
記録時には、上記のごとく第２の照射手段によ
り焦点制御を行ないながら、第１の照射手段を次
のごとく動作させる。すなわち、第１のレーザ１
からのレーザビームをコリメータレンズ２により
平行ビームにし、光変調器３により記録すべき情
報に応じてレーザビームを強度変調し、被変調レ
ーザビームはビームスプリツタ４により直線偏向
され、1/4波長板５により円偏波となり、ダイク
ロミツクミラー６を通過し、集光レンズ７の光軸
に一致して通過して、記録層８上に焦点Ｂを結び
記録層８に孔を形成する。この際、前記第２の照
射ビームの焦点Ｃが、記録層８の第１の照射ビー
ムの焦点Ｂよりも走行方向前位側の未だ何も記録
されていない（孔のあいていない）平担部分で結
ばれるので、焦点制御信号はノイズの少ない、従
つてＳ／Ｎ比の良好なものが得られて精度の良い
焦点制御ができると共に、第２の照射ビームによ
り記録層８を記録しきい値よりも小さいパワーで
予熱して記録層８の感度を高めておき、次に第１
の照射ビームにより焦点Ｂ位置で記録しきい値よ
りも大きいパワーで記録する。従つて記録層とし
ては感度がある程度悪くても記録ができると共
に、第１のレーザ１０はパワーの小さいものを用
いることができる。また第２のレーザ１０として
は単に予熱と焦点制御を用えばよいので、コヒー
レンシの低い安価なレーザを使用することができ
る。 During recording, the first irradiation means is operated as follows while the second irradiation means performs focus control as described above. That is, the first laser 1
A collimator lens 2 converts the laser beam into a parallel beam, an optical modulator 3 modulates the intensity of the laser beam according to the information to be recorded, and the modulated laser beam is linearly deflected by a beam splitter 4 to produce a 1/4 wavelength beam. The wave becomes circularly polarized by the plate 5, passes through the dichroic mirror 6, and passes along the optical axis of the condensing lens 7 to form a focal point B on the recording layer 8, forming a hole in the recording layer 8. At this time, the focus C of the second irradiation beam is set on a flat surface on which nothing is recorded yet (without holes) on the front side of the recording layer 8 in the traveling direction than the focus B of the first irradiation beam. Since the focus control signal has less noise and a good S/N ratio, it is possible to perform focus control with high precision, and the second irradiation beam can reach the recording layer 8 at the recording threshold. The sensitivity of the recording layer 8 is increased by preheating with a power lower than the value, and then the first
Recording is performed at the focal point B position using the irradiation beam with a power greater than the recording threshold. Therefore, recording can be performed as a recording layer even if the sensitivity is poor to some extent, and a laser with low power can be used as the first laser 10. Moreover, since preheating and focus control may be simply used as the second laser 10, an inexpensive laser with low coherency can be used.
次に再生時には、前述のごとく第２の照射手段
により焦点制御を行ないながら、第１のレーザ１
のパワーを落とすかあるいは第１のレーザ１の次
に図示しないフイルタを挿入して第１のレーザビ
ームを記録層の記録しきい値以下にパワーを落と
し、この弱い第１の照射ビームにより記録層８上
に焦点Ｂを結ばせ、記録情報としての孔の乱反射
に伴う暗部を含む反射ビームを集光レンズ７、ダ
イクロミツクミラー６を通して1/4波長板５で円
偏波から入射ビームとは直角な直線偏波に変換さ
れ、ビームスプリツタ４で入射ビームと分離反射
させてフオトデイテクタ９で受光し、受光量に応
じて変換される電気信号により再生信号を得る。
この場合に第２のレーザビームによる焦点はコヒ
ーレンシのあまりよくないレーザを用いているた
めに記録された孔の径よりもかなり大きな焦点面
積を有する。従つて孔による乱反射に基づくノイ
ズの影響が小さく、再生の場合にもＳ／Ｎ比の大
きな焦点制御用信号を得ることができる。 Next, during reproduction, the focus of the first laser 1 is controlled by the second irradiation means as described above.
Either the power of the first laser beam is reduced or a filter (not shown) is inserted next to the first laser beam 1 to reduce the power of the first laser beam to below the recording threshold of the recording layer, and this weak first irradiation beam is used to irradiate the recording layer. 8, and the reflected beam including the dark part caused by the diffused reflection of the hole as recorded information is passed through the condenser lens 7 and the dichroic mirror 6, and the 1/4 wavelength plate 5 converts it into a circularly polarized wave at right angles to the incident beam. The light is converted into a linearly polarized wave, separated from the incident beam by the beam splitter 4 and reflected, and received by the photodetector 9. A reproduced signal is obtained from an electric signal converted according to the amount of received light.
In this case, the focus area of the second laser beam has a much larger focal area than the diameter of the recorded hole because a laser with poor coherency is used. Therefore, the influence of noise due to diffused reflection by the holes is small, and a focus control signal with a high S/N ratio can be obtained even during reproduction.
さらに消去時には、第１のレーザは消灯し、第
２のレーザ１０のパワーを上げて記録しきい値よ
りも大きくすると共に、焦点の直径を記録されて
いる孔の直径よりも大きくする。こうすると記録
層８は第２の照射ビームの直径を幅として連続的
に融解され、孔が消滅する。この場合も再生時と
同様の理由で焦点制御用信号のＳ／Ｎ比は大きい
ものが得られる。 Furthermore, during erasing, the first laser is turned off and the power of the second laser 10 is increased to exceed the recording threshold and to make the diameter of the focal spot larger than the diameter of the hole being recorded. In this way, the recording layer 8 is continuously melted with a width equal to the diameter of the second irradiation beam, and the holes disappear. In this case as well, a high S/N ratio of the focus control signal can be obtained for the same reason as during reproduction.
以上詳述したように、本発明の光記録系の焦点
制御装置によれば、第２の照射手段により記録層
の第１の照射手段による記録・再生用の照射ビー
ムの焦点よりも走行方向前位側の部分から得られ
た反射ビームにより焦点制御信号を得るようにし
たので、記録された孔の乱反射に基づくノイズの
影響の小さいＳ／Ｎ比の大きな焦点制御用信号を
得ることができて、精度のよい焦点制御を行なう
ことができ、また記録時にはこの第２の照射手段
による照射ビームを予熱用として利用するので、
記録用の第１の照射手段のレーザにパワーの小さ
いものを用いることができると共に、予熱するた
めに感度のあまり良くない記録層で構成された記
録媒体の使用が可能であり、さらに消去可能な記
録媒体に対しては第２の照射手段を消去用として
用いることができる、という数々の利点を有す
る。そして第２の照射手段のレーザにはコヒーレ
ンシのそれ程良くない、かつパワーの大きい安価
なレーザを使用することができ、総じて光記録系
全体のコストを低くすることができる。 As described in detail above, according to the focus control device for an optical recording system of the present invention, the second irradiation means causes the recording layer to be irradiated in front of the focus of the irradiation beam for recording and reproduction by the first irradiation means in the traveling direction. Since the focus control signal is obtained from the reflected beam obtained from the side part, it is possible to obtain a focus control signal with a high S/N ratio and a small influence of noise based on the diffused reflection of the recorded hole. It is possible to perform accurate focus control, and since the irradiation beam from this second irradiation means is used for preheating during recording,
It is possible to use a laser of low power as the first irradiation means for recording, and it is also possible to use a recording medium composed of a recording layer that is not very sensitive for preheating, and it is also possible to use a recording medium that is erasable. This has a number of advantages in that the second irradiation means can be used for erasing the recording medium. Further, as the laser of the second irradiation means, an inexpensive laser with low coherency and high power can be used, and the cost of the entire optical recording system can be reduced in general.
図は本発明の光記録系の焦点制御装置の一実施
例を示す系統図である。
１……第１のレーザ、３……光変調器、４……
ビームスプリツタ、７……集光レンズ、８……記
録層、９……フオトデイテクタ、１０……第２の
レーザ、１２……ビームスプリツタ、１４……２
分割フオトデイテクタ、１４ａ……分離点、１４
ｂ，１４ｃ……フオトデイテクタ、１５……巻
線。
The figure is a system diagram showing an embodiment of a focus control device for an optical recording system according to the present invention. 1... First laser, 3... Optical modulator, 4...
Beam splitter, 7...Condensing lens, 8...Recording layer, 9...Photodetector, 10...Second laser, 12...Beam splitter, 14...2
Divided photodetector, 14a...Separation point, 14
b, 14c...Photodetector, 15...Winding.
Claims (1)
録・再生用の第１の照射手段と、第２のレーザか
らのレーザビームによる焦点制御用の第２の照射
手段とを有し、第２の照射手段による入射レーザ
ビームが前記第１の照射手段の集光レンズの光軸
を外れた部分を通過すると共に、記録層上におけ
るその焦点が前記第１の照射手段のレーザビーム
の焦点よりも記録層の走行方向前位側に結ばれ、
該第２の照射手段のレーザビームの記録層上から
の反射ビームを前記焦光レンズのさらに光軸を外
れた部分を通過させて２分割フオトデイテクタで
受光し、前記記録層の集光レンズの焦点からのズ
レに応じた前記２分割フオトデイテクタの受光量
の増減により焦点制御用信号を得、記録・再生お
よび消去時に該焦点制御信号により集光レンズの
位置を調節して記録層上に集光レンズの焦点を合
致させる焦点制御を行なうと共に、前記第２の照
射手段のレーザビームにより、記録時の記録層の
予熱および消去時の記録孔の消去を行なうことを
特徴とする光記録系の焦点制御装置。1 A first irradiation means for recording/reproduction using a laser beam from a first laser, and a second irradiation means for focus control using a laser beam from a second laser, the second irradiation means The incident laser beam passes through a portion off the optical axis of the condensing lens of the first irradiation means, and its focus on the recording layer is closer to the recording layer than the focus of the laser beam of the first irradiation means. Tied to the front side in the running direction,
The reflected beam of the laser beam of the second irradiation means from above the recording layer is passed through a part of the focusing lens that is further off the optical axis, and is received by a two-split photodetector, so that the beam is reflected by the focusing lens of the recording layer. A focus control signal is obtained by increasing or decreasing the amount of light received by the two-split photodetector according to the deviation from the recording layer, and the position of the condensing lens is adjusted by the focus control signal during recording, reproduction, and erasing, and the condensing lens is placed on the recording layer. Focus control for an optical recording system, characterized in that the laser beam of the second irradiation means is used to preheat a recording layer during recording and erase recording holes during erasing. Device.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5712681A JPS57172306A (en) | 1981-04-17 | 1981-04-17 | Focus controller of optical recording system |
| US06/362,983 US4530080A (en) | 1981-04-07 | 1982-03-29 | Optical recording/reproducing system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5712681A JPS57172306A (en) | 1981-04-17 | 1981-04-17 | Focus controller of optical recording system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS57172306A JPS57172306A (en) | 1982-10-23 |
| JPS6367256B2 true JPS6367256B2 (en) | 1988-12-23 |
Family
ID=13046864
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP5712681A Granted JPS57172306A (en) | 1981-04-07 | 1981-04-17 | Focus controller of optical recording system |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS57172306A (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH01151428U (en) * | 1988-04-06 | 1989-10-19 | ||
| JP2757541B2 (en) * | 1990-06-29 | 1998-05-25 | キヤノン株式会社 | Focus detection device and observation device having the same |
| CN101862902A (en) * | 2010-03-11 | 2010-10-20 | 广东海洋大学 | Handheld laser welding method and device |
| CN101862912A (en) * | 2010-03-11 | 2010-10-20 | 广东海洋大学 | Handheld laser drilling method |
| CN101862911A (en) * | 2010-03-11 | 2010-10-20 | 广东海洋大学 | Handheld laser cutting method |
-
1981
- 1981-04-17 JP JP5712681A patent/JPS57172306A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS57172306A (en) | 1982-10-23 |
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