JPH02240837A - Defocus detector for optical head - Google Patents
Defocus detector for optical headInfo
- Publication number
- JPH02240837A JPH02240837A JP6063989A JP6063989A JPH02240837A JP H02240837 A JPH02240837 A JP H02240837A JP 6063989 A JP6063989 A JP 6063989A JP 6063989 A JP6063989 A JP 6063989A JP H02240837 A JPH02240837 A JP H02240837A
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- Prior art keywords
- light
- focus
- optical
- amount
- reflected
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- 230000003287 optical effect Effects 0.000 title claims abstract description 39
- 238000001514 detection method Methods 0.000 claims abstract description 17
- 238000005259 measurement Methods 0.000 claims description 25
- 239000013307 optical fiber Substances 0.000 claims description 18
- 238000003384 imaging method Methods 0.000 claims description 3
- 238000012634 optical imaging Methods 0.000 claims description 3
- 239000000835 fiber Substances 0.000 claims 1
- 239000004065 semiconductor Substances 0.000 abstract description 6
- 238000000926 separation method Methods 0.000 description 6
- 230000007423 decrease Effects 0.000 description 5
- 238000010586 diagram Methods 0.000 description 5
- 238000004364 calculation method Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
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- Optical Recording Or Reproduction (AREA)
Abstract
Description
【発明の詳細な説明】
[産業上の利用分野]
本発明は光ヘッドの焦点ずれ検出装置に関するものであ
る。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a defocus detection device for an optical head.
[従来の技術]
光デイスク装置に用いられているの従来の光ヘッドにお
いては、ディスクに焦点を合せるための焦点ずれ検出装
置は、例えば特公昭62−45612号公報に示される
ように記録面から反射される直線偏光したビームをグラ
ントムソンプリズムにてPII光とS[光とに分離し、
そのグラントムソンプリズムの接合面にて反射されたS
開光成分の反射光束の形状変化を分割型光検出器で検出
することで焦点ずれを検出していた。すなわち、合焦点
時にグラントムソン1リズノNの接合面で反射される光
束の中心で分割された二つの受光素子からなる分割型光
検出器で反射光束を検出し、焦点ずれによって変わる両
受光素子の出力信号の差をとることで焦点ずれを検出す
るようにしている。[Prior Art] In a conventional optical head used in an optical disk device, a defocus detecting device for focusing on the disk detects a defocus from the recording surface as shown in Japanese Patent Publication No. 62-45612, for example. The reflected linearly polarized beam is separated into PII light and S[light by a Glan-Thompson prism,
S reflected at the cemented surface of the Glan-Thompson prism
Defocus was detected by detecting changes in the shape of the reflected light beam of the open light component using a split photodetector. In other words, the reflected light beam is detected by a split-type photodetector consisting of two light-receiving elements that are split at the center of the light beam reflected at the cemented surface of the Glan-Thompson 1 Rizno N at the time of focusing, and the difference between the two light-receiving elements changes depending on the focus shift. Defocus is detected by taking the difference between the output signals.
[発明が解決しようとする課題]
しかしながら、分割された両受光素子の出力信号の差よ
り焦点ずれを検出するには両受光素子の受光量調整を行
なわなければならない。[Problems to be Solved by the Invention] However, in order to detect a defocus from the difference between the output signals of both the divided light receiving elements, it is necessary to adjust the amount of light received by both the light receiving elements.
また両受光素子や光学部品の位置ずれや周囲温度変化や
振動などによりオフセットが生じやすい問題がある。さ
らに光ヘッドは光学系とアクチュエータ系が一体となっ
ており、小型軽量化が難しい問題があった。There is also the problem that offset is likely to occur due to misalignment of both light receiving elements or optical components, changes in ambient temperature, vibrations, etc. Furthermore, the optical head has an optical system and an actuator system integrated, making it difficult to make it smaller and lighter.
本売りの目的は前記した従来技術の欠点を解消し、焦点
ずれを全光量により検出して光学系の調整が簡単にでき
、しかも温度変化や振動などにより誤差を生じることが
ない光ヘッドの焦点ずれ検出装置を提供することにある
。The purpose of this sale is to eliminate the drawbacks of the conventional technology described above, to detect defocusing using the total light intensity, to easily adjust the optical system, and to focus an optical head that does not cause errors due to temperature changes or vibrations. An object of the present invention is to provide a deviation detection device.
[課題を解決するための手段]
本発明の要旨は、レーザビームを一端から放射する光フ
ァイバと、そのレーザビームを光ディスクの情報記録面
上に光スポットとして結像するための光学的結像手段と
、上記光ファイバの他端側に設けられ光ファイバを通し
ての反射光量を検出する光検出器と、上記光ディスクに
形成され、上記情報記録面から上記光スポットの焦点深
度以上離れ、かつ光スポットの直径以上の大きさに形成
された焦点測定用面と、上記光スポットの焦点が前記情
報記録面上にあるときの上記焦点測定用面からの反射光
量をホールドし、かつそのホールドした反射光量と焦点
測定用面からの反射光量とで焦点ずれを検出する信号処
理回路とを備えたものである。[Means for Solving the Problems] The gist of the present invention is to provide an optical fiber that emits a laser beam from one end, and an optical imaging means for imaging the laser beam as a light spot on the information recording surface of an optical disk. a photodetector provided on the other end of the optical fiber to detect the amount of reflected light passing through the optical fiber; A focus measuring surface formed to a size larger than a diameter, and holding the amount of reflected light from the focus measuring surface when the focus of the light spot is on the information recording surface, and the held reflected light amount and It is equipped with a signal processing circuit that detects defocus based on the amount of light reflected from the focus measurement surface.
[作用]
上記構成によれば、光ディスクに情報記録面とは別に焦
点測定用面を形成し、情報記録面上に光スポットが焦点
があったときの焦点測定用面からの反射光量をホールド
し、このホールドした反射光量と常時焦点測定用面から
の反射光量との差を検出することで焦点ずれ量と方向が
検出できる。[Function] According to the above configuration, a focus measurement surface is formed on the optical disk separately from the information recording surface, and the amount of light reflected from the focus measurement surface when the light spot is focused on the information recording surface is held. By detecting the difference between the held amount of reflected light and the amount of reflected light from the constant focus measurement surface, the amount and direction of defocus can be detected.
[実施例]
以下本発明の好適実施例を添付図面に基づいて説明する
。[Embodiments] Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.
第1図において、1は2波長(例えば波長830niと
波長780n11)ハイブリッド半導体レーザ、2はレ
ーザ1からの出射光を平行光とするコリメートレンズ、
3はビームスプリッタ、4は各レーザ光を絞り込んで夫
々光ファイバ5a、5bに入射させる絞り込みレンズ、
6は光ファイバ5 a + 5 bの出射端5 a o
+ 5 b oから出射されたレーザ光を平行光とす
るコリメートレンズ、7はコリメートレンズ7からのレ
ーザ光をディスク8に焦点9a、9bを合すべく結像す
る光学的結像手段である絞り込みレンズ、10は絞り込
みレンズ7のフォーカス及びトラッキング用アクチュエ
ータである。In FIG. 1, 1 is a hybrid semiconductor laser with two wavelengths (for example, wavelength 830ni and wavelength 780n11), 2 is a collimating lens that converts the light emitted from the laser 1 into parallel light,
3 is a beam splitter; 4 is a focusing lens that narrows down each laser beam and makes it enter the optical fibers 5a and 5b, respectively;
6 is the output end 5 a o of the optical fiber 5 a + 5 b
+ 5 A collimating lens that converts the laser beam emitted from b o into parallel light; 7 is an optical focusing means that focuses the laser beam from the collimating lens 7 on the disk 8 to focus 9a and 9b. A lens 10 is an actuator for focusing and tracking the aperture lens 7.
ディスク8は、その情報記録面11に対してレザ光の光
スポットの焦点深度以上離れ、かつ光スポットの径より
大きく形成された焦点測定用面12が形成され、例えば
図示のように情報記録面11に対して凹部を形成し、そ
の底面に焦点測定用面12を形成するか或いは図示して
いないが情報記録面11に対して凸部を形成し、その上
面に焦点測定用面12を形成する。The disk 8 has a focus measurement surface 12 formed at a distance from the information recording surface 11 by more than the focal depth of the optical spot of the laser beam and larger than the diameter of the optical spot. 11, and the focus measurement surface 12 is formed on the bottom surface thereof, or, although not shown, a convex portion is formed on the information recording surface 11, and the focus measurement surface 12 is formed on the top surface thereof. do.
また、13はビームスプリッタ3にて反射されたレーザ
光の波長分離フィルタ、14は波長分離フィルタ13で
反射されビームスプリッタ3を透過したレーザ光を検出
する光検出器、15は波長分離フィルタ13を透過した
レーザ光をPli光とSwi光に分離する偏光ビームス
プリッタ、16a。Further, 13 is a wavelength separation filter for the laser beam reflected by the beam splitter 3, 14 is a photodetector for detecting the laser beam reflected by the wavelength separation filter 13 and transmitted through the beam splitter 3, and 15 is a wavelength separation filter for the wavelength separation filter 13. A polarizing beam splitter 16a that separates the transmitted laser light into Pli light and Swi light.
16bはそれぞれPI光とS偏光のレーザ光を検出する
光検出器である。16b is a photodetector that detects PI light and S-polarized laser light, respectively.
この光検出器16a、16bの出力は信号処理回路17
に入力され、また他方の光検出器14の出力も別の信号
処理回路18に入力され、この信号処理回路18の出力
が一方の信号処理回路17からライン19を介してフォ
ーカス及びトラッキング用アクチュエータ10が駆動さ
れるようになっている。The outputs of these photodetectors 16a and 16b are transmitted to a signal processing circuit 17.
The output of the other photodetector 14 is also input to another signal processing circuit 18, and the output of this signal processing circuit 18 is sent from one signal processing circuit 17 to the focusing and tracking actuator 10 via a line 19. is now driven.
また、第1図において点線20で囲んだ部分、すなわち
半導体レーザ1や光検出器14.16a。Also, the portion surrounded by the dotted line 20 in FIG. 1, that is, the semiconductor laser 1 and the photodetector 14.16a.
16bなどは光デイスク装置内に固定れさ、点線21で
囲んだ部分、すなわち絞り込みレンズ7などは光ヘッド
に組み込まれている。16b and the like are fixed within the optical disk device, and the portion surrounded by the dotted line 21, that is, the aperture lens 7, etc., is incorporated into the optical head.
以上において、2波長(例えば波長830nmと波長7
80nm )ハイブリッド半導体レーザ1から出射した
レーザ光をコリメートレンズ2を用いて平行光にする。In the above, two wavelengths (for example, wavelength 830 nm and wavelength 7
80 nm) A laser beam emitted from a hybrid semiconductor laser 1 is made into parallel light using a collimating lens 2.
ビームスプリッタ3を通過したレーザ光は、絞り込みレ
ンズ4によって波長別に、例えば波長830nmのレー
ザ光束は光ファイバ5aに入射し、波長780nlのレ
ーザ光束は光ファイバ5bに入射する。その後光ファイ
バ出射端5a0゜5b、から出射したレーザ光束は、コ
リメートレンズ6で平行光とされ、光学的結像手段であ
る絞り込みレンズ7によって情報記録面11上に焦点9
a、9bを結ぶ。The laser light that has passed through the beam splitter 3 is divided into wavelengths by a focusing lens 4. For example, a laser beam with a wavelength of 830 nm enters an optical fiber 5a, and a laser beam with a wavelength of 780 nl enters an optical fiber 5b. Thereafter, the laser beam emitted from the optical fiber output ends 5a0, 5b is converted into parallel light by a collimating lens 6, and is brought to a focal point 9 on the information recording surface 11 by a diaphragm lens 7, which is an optical imaging means.
Connect a and 9b.
そして、情報記録面11又は焦点測定用面12で反射さ
れたレーザ光束は上述した往路を逆行してビームスプリ
ッタ3まで達し、今度はビームスプリッタ3で反射され
、波長分離フィルタ13で反射したレーザ光束(例えば
波長780nIlレ一ザ光束)は、ビームスプリッタ3
を透過し、光検出器14に入射し、光検出器14で焦点
測定用面12からの反射光量が検出される。Then, the laser beam reflected by the information recording surface 11 or the focus measurement surface 12 travels the above-mentioned forward path in the reverse direction and reaches the beam splitter 3, and is then reflected by the beam splitter 3 and the laser beam reflected by the wavelength separation filter 13. (For example, the wavelength of 780nIl laser beam) is from the beam splitter 3.
The light passes through the beam, enters the photodetector 14, and the amount of reflected light from the focus measurement surface 12 is detected by the photodetector 14.
また波長分離フィルタ13を透過したレーザ光束(波長
830nn )は偏光ビームスグリツタ15でP11光
分とSl光分とに分離され、それぞれ光検出器16a、
16bで情報記録面11からの反射光量が検出される。Further, the laser beam (wavelength 830 nn) that has passed through the wavelength separation filter 13 is separated into a P11 light component and a Sl light component by a polarizing beam sinter 15, which are detected by a photodetector 16a,
At 16b, the amount of reflected light from the information recording surface 11 is detected.
本発明においては、波長830n1mのレーザ光が情報
記録面11に合焦点時、光検出器14で検出される焦点
測定用面12からの波長780nnのレーザ光の反射光
量を信号処理回路17.18でホールドし、このホール
ドした反射光量と任意の時に検出器14で検出した焦点
測定用面12からの反射光量との差をとることで焦点ず
れ信号が検出できる。In the present invention, when the laser beam with a wavelength of 830 nm is focused on the information recording surface 11, the signal processing circuit 17. A defocus signal can be detected by holding the held amount of reflected light and calculating the difference between the amount of reflected light from the focus measuring surface 12 detected by the detector 14 at any time.
この焦点ずれ検出の原理を第3図(a)〜(b)及び第
4図(a)、(b)により説明する。The principle of this defocus detection will be explained with reference to FIGS. 3(a) to (b) and FIGS. 4(a) and (b).
先ず、第4図(a)、 (b)に示すように光ファイバ
5aから放射され、コリメートレンズ6で平行とされ絞
りレンズ7で絞り込まれた光スポットが実線で示した情
報記録面ll上に焦点9aがあると、し、その情報記録
面11が実線の位置から第4図(a)に点線で示すよう
に絞り込みレンズ7より遠ざかる方向にずれた場合と、
絞り込みレンズ7に近づく方向にずれた場合、その点線
の情報記録面11から反射されるレーザ光は図示の点線
で示したような光路を通って光ファイバ5aに入射され
るが、実線で示した合焦点時の光路に対して光ファイバ
5aに入射される光量は少なくなる。このように光ディ
スク13の光軸方向のずれにより反射光量が変化する。First, as shown in FIGS. 4(a) and 4(b), a light spot is emitted from the optical fiber 5a, made parallel by the collimating lens 6, and narrowed down by the aperture lens 7, onto the information recording surface ll shown by the solid line. If there is a focal point 9a, and if the information recording surface 11 is shifted away from the diaphragm lens 7 from the solid line position as shown by the dotted line in FIG. 4(a),
When the laser beam is shifted in the direction approaching the diaphragm lens 7, the laser beam reflected from the information recording surface 11 indicated by the dotted line enters the optical fiber 5a through the optical path shown by the dotted line in the figure, but the laser light is incident on the optical fiber 5a as shown by the solid line. The amount of light incident on the optical fiber 5a is smaller than the optical path at the time of focus. In this way, the amount of reflected light changes depending on the deviation of the optical disk 13 in the optical axis direction.
さて先ず、第3図(1))に示すように情報検出用のレ
ーザ光(830rv)の焦点9aが情報記録面11上に
あるときは、第3図(d)に示すように、その反射光の
受光量22は最大となり、焦点がずれることにより受光
量23.24は少なくなり、第3図(d)に示すような
受光特性が得られる。First, when the focal point 9a of the laser beam (830rv) for information detection is on the information recording surface 11 as shown in FIG. 3(1)), the reflection The amount of received light 22 becomes maximum, and the amount of received light 23.24 decreases due to the shift of focus, resulting in the light receiving characteristics shown in FIG. 3(d).
他方、第3図(a)に示すように焦点測定用レーザ光(
78GnIl)は、第3図(b)のように情報検出用レ
ーザ光の焦点9aが情報記録面ll上にあるときは、そ
の焦点りbは情報記録面11にあるため、焦点測定用面
12からの反射光の受光量は少なく、この焦点測定用面
12が、さらに絞り込みレンズ7より離れると受光量が
少なくなり、逆に近づけば受光量が多くなり、その受光
特性は、第3図(C)に示したように、情報記録面11
からの反射光の受光量の特性(第3図(d))に対し、
情報記録面11と焦点測定用面12間の距離分ずれた位
置に最大受光量32を有するものとなる。On the other hand, as shown in Fig. 3(a), the focus measurement laser beam (
78GnIl), when the focal point 9a of the information detection laser beam is on the information recording surface ll as shown in FIG. The amount of reflected light received from the focus measuring surface 12 is small, and as the focus measuring surface 12 moves further away from the diaphragm lens 7, the amount of received light decreases, and conversely, as it gets closer, the amount of received light increases.The light receiving characteristics are shown in Figure 3 ( As shown in C), the information recording surface 11
Regarding the characteristics of the amount of reflected light received from the (Fig. 3 (d)),
The maximum amount of light received 32 is at a position shifted by the distance between the information recording surface 11 and the focus measurement surface 12.
従って、令弟3図(b)に示したように情報検出用レー
ザ光の焦点9aが情報記録面11上にあるとき(合焦点
)の焦点測定用レーザの反射光の受光量、すなわち第3
図+C)に示す焦点ずれゼロのときの受光量25をホー
ルドし、このホールドした受光量25と任意の時の焦点
測定用面12がらの受光量とを比較すれば焦点ずれ量と
その方向が判る。Therefore, as shown in FIG. 3(b), when the focal point 9a of the information detection laser beam is on the information recording surface 11 (focused point), the amount of the reflected light from the focus measurement laser, that is, the third
By holding the amount of received light 25 when the focus shift is zero as shown in Figure +C) and comparing this held amount of received light 25 with the amount of light received from the focus measuring surface 12 at any time, the amount of focus shift and its direction can be determined. I understand.
この焦点ずれに対する焦点ずれ信号は、第5図に示した
特性となる。The defocus signal corresponding to this defocus has the characteristics shown in FIG.
次に信号処理回路17.18での焦点ずれ検出のブロッ
ク図を第6図により説明する。Next, a block diagram of defocus detection in the signal processing circuits 17 and 18 will be explained with reference to FIG.
まず、光検出器16aと16bの出力回路26で全光量
の和をとる。First, the output circuit 26 of the photodetectors 16a and 16b calculates the sum of the total light amounts.
次に順次、この光検出器16aと16bの和を前の和と
比較する回路27を設け、ピーク検出回路28でピーク
検出する(第3図(d)の受光量22)、ピーク検出し
たら焦点測定用の光検出器14の出力29をホールドす
る回路32を設けることにより、情報記録面11上に焦
点が合っている時の焦点測定用面12の反射光の受光量
25が検出できる。Next, a circuit 27 is provided to sequentially compare the sum of these photodetectors 16a and 16b with the previous sum, and a peak detection circuit 28 detects the peak (light reception amount 22 in FIG. 3(d)). By providing a circuit 32 that holds the output 29 of the measurement photodetector 14, the amount 25 of the reflected light received by the focus measurement surface 12 when the information recording surface 11 is in focus can be detected.
次に焦点が任意の時の光検出器14の出力30を差動演
算回路33に入力し、焦点が合っている時の焦点測定用
面12の反射光の受光量25と差をとると、第5図に示
す焦点ずれ検出信号が得られる。Next, input the output 30 of the photodetector 14 when the focus is arbitrary to the differential calculation circuit 33, and take the difference from the amount 25 of the reflected light received by the focus measurement surface 12 when the focus is in place. A defocus detection signal shown in FIG. 5 is obtained.
これよりディスク8のずれた方向とずれ量がわかるので
、第1図に示した絞り込みレンズ7をレンズ光軸方向に
動かず公知のフォーカシングアクチュエータ10に、第
5図の焦点ずれ検出信号を入力することにより自動焦点
制御が達成される。From this, the direction and amount of deviation of the disk 8 can be determined, so input the defocus detection signal shown in FIG. 5 to the known focusing actuator 10 without moving the diaphragm lens 7 shown in FIG. 1 in the lens optical axis direction. Automatic focus control is thereby achieved.
トラッキング制御には、光検出器16a。A photodetector 16a is used for tracking control.
16bの出力信号により、絞り込みレンズ7をトラッキ
ングずれ方向に動かす公知のトラッキングアクチュエー
タ10を用いることができる。A known tracking actuator 10 can be used that moves the aperture lens 7 in the direction of tracking deviation based on the output signal of the output signal 16b.
第7図はディスク8の情報記録面11上のあるトラック
35を示すもので、トラックに沿って両側に微少にずれ
た凹凸ビット34aと34b(第7図(a))がある。FIG. 7 shows a certain track 35 on the information recording surface 11 of the disk 8, and there are concave and convex bits 34a and 34b (FIG. 7(a)) slightly shifted on both sides along the track.
光スポットがトラック35上を走査する場合には、光検
出器16aと16bの出力信号は第7図(b)に示すよ
うに凹凸ビット34aと34bの所で同じ程度減少する
。光スポットがトラック35から紙面下方向にずれて点
線36上を走査した場合、出力信号は第7図fc)に示
す様に凹凸ビット34aの所で大きく減少し、凹凸ビッ
ト34bの所では減少は小さい。When the light spot scans over the track 35, the output signals of the photodetectors 16a and 16b decrease to the same extent at the uneven bits 34a and 34b, as shown in FIG. 7(b). When the light spot shifts downward from the track 35 and scans on the dotted line 36, the output signal decreases greatly at the uneven bit 34a, as shown in FIG. small.
逆に点線37上を走査した場合は第7図1d)に示す様
に、凹凸ビット34aの所で減少は小さく、凹凸ビット
34bの所では減少が大きい、よって凹凸ビット34a
と34bで変調された信号レベルを比べれば、トラック
ずれ信号が得られるので、トラッキングアクチュエータ
10を用いてトラッキング制御が達成できる。Conversely, when scanning on the dotted line 37, as shown in FIG. 7 1d), the decrease is small at the uneven bit 34a and large at the uneven bit 34b.
By comparing the signal level modulated by 34b and 34b, a track deviation signal can be obtained, so that tracking control can be achieved using the tracking actuator 10.
情報信号の再生は光検出器16aと16bの差をとるこ
とで検出することができる。Reproduction of the information signal can be detected by taking the difference between the photodetectors 16a and 16b.
また、情報の記録は、2波長ハイブリッド半導体レーザ
1の出力をパルス的に上げて行なうことは、公知の通り
である。Furthermore, as is known, information is recorded by increasing the output of the two-wavelength hybrid semiconductor laser 1 in a pulsed manner.
次に光ディスクは、第2図に示すように、ディスク半径
方向に凹部(又は凸部)が作成され焦点測定用面12が
形成されている。また、この焦点測定用面12の深さは
焦点深度以上でかつ幅はスポット径以上である0例えば
凹部で焦点測定用面12を形成すると、その凹部の深さ
、幅誹(に10μm程度にする。Next, as shown in FIG. 2, the optical disc has a recess (or a convex part) formed in the radial direction of the disc to form a focus measurement surface 12. Further, the depth of the focus measurement surface 12 is greater than or equal to the focal depth, and the width is greater than or equal to the spot diameter. For example, if the focus measurement surface 12 is formed of a concave portion, the depth and width of the concave portion (approximately 10 μm) do.
この様な焦点測定用面12を持ったディスクの作成法を
以下に説明する。A method of manufacturing a disk having such a focus measurement surface 12 will be described below.
まず第8図(a)に示す様に深さ、幅共に10μl程度
の湧40をディスク8の半径方向にカッティングする0
次に第8図(b)に示す様に反射141(情報記録面)
を設け、更に保護r!A42を設ける。First, as shown in FIG. 8(a), a spring 40 with a depth and width of about 10 μl is cut in the radial direction of the disk 8.
Next, as shown in FIG. 8(b), the reflection 141 (information recording surface)
and further protection r! A42 is provided.
以上より第8図(C)に示す様に、情報記録面11より
凹(又は凸)した焦点測定用面12が形成される。From the above, as shown in FIG. 8(C), the focus measurement surface 12 that is concave (or convex) from the information recording surface 11 is formed.
以上本実施例によれば全光量によって焦点ずれが検出で
きるので、光ファイバを用いて移動光学部21を形成す
ることが可能となり、小型軽量化が実現でき、高速アク
セスが可能となる。As described above, according to the present embodiment, since defocus can be detected based on the total amount of light, it becomes possible to form the moving optical section 21 using an optical fiber, making it possible to realize a reduction in size and weight, and to enable high-speed access.
また前述した様に、移動用光ヘツド部内において、いろ
いろな部品がずれた場合にも点結像関係が保たれている
ので、焦点ずれ検出信号に誤差を生じない。Furthermore, as described above, even if various parts are displaced within the movable optical head, the point imaging relationship is maintained, so no error occurs in the defocus detection signal.
[発明の効果]
以上説明したように本発明によれば、全光量によって焦
点ずれ検出信号を得ることができるので、焦点合せのた
めの光学的調整が不要で、温度変化、振動などによって
光学部品の位置ずれが生じた場合にも、検出信号に誤差
を生じない光フアイバヘッドに好適な焦点ずれ検出光学
系が実現でき、アクセスの時移動する部分が小型・軽量
な光ヘッドが実現できる。[Effects of the Invention] As explained above, according to the present invention, it is possible to obtain a defocus detection signal based on the total amount of light, so there is no need for optical adjustment for focusing, and optical components may be damaged due to temperature changes, vibrations, etc. It is possible to realize a defocus detection optical system suitable for an optical fiber head that does not produce an error in the detection signal even when a positional deviation occurs, and it is possible to realize an optical head whose parts that move during access are small and lightweight.
第1図は本発明の一実施例を示す光学系構成図、第2図
は本発明における光ディスクの全体平面図、第3図は本
発明において焦点ずれの検出原理を示す図、第4図は本
発明において情報記録面のずれにおける反射光路の変化
を示す図、第5図は本発明において焦点ずれに対する焦
点ずれ信号を示す図、第6図は第1図における信号処理
回路のブロック図、第7図は本発明においてトラックず
れW@整を説明する図、第8図は本発明において光ディ
スクの詳細断面図である。
図中、1は半導体レーザ、5a、5bは光ファイバ、7
は光学的結像手段としての絞り込みレンズ、8は光ディ
スク、11は情報記録面、12は焦点測定用面、14.
16a、16bは光検出器、17.18は信号処理回路
である。
特許出願人 日立電線株式会社
株式会社日立製作所
代理人弁理士 絹 谷 信 雄
(b)
第4図
第5図FIG. 1 is a block diagram of an optical system showing an embodiment of the present invention, FIG. 2 is an overall plan view of an optical disc in the present invention, FIG. 3 is a diagram showing the principle of detecting defocus in the present invention, and FIG. In the present invention, FIG. 5 is a diagram showing the change in the reflected optical path due to the deviation of the information recording surface, FIG. FIG. 7 is a diagram for explaining track deviation W@adjustment in the present invention, and FIG. 8 is a detailed sectional view of the optical disc in the present invention. In the figure, 1 is a semiconductor laser, 5a and 5b are optical fibers, and 7
8 is an optical disk; 11 is an information recording surface; 12 is a focus measurement surface; 14.
16a and 16b are photodetectors, and 17.18 is a signal processing circuit. Patent applicant Hitachi Cable, Ltd. Hitachi, Ltd. Patent attorney Nobuo Kinutani (b) Figure 4 Figure 5
Claims (1)
のレーザビームを光ディスクの情報記録面上に光スポッ
トとして結像するための光学的結像手段と、上記光ファ
イバの他端側に設けられ光ファイバを通しての反射光量
を検出する光検出器と、上記光ディスクに形成され、上
記情報記録面から上記光スポットの焦点深度以上離れ、
かつ光スポットの直径以上の大きさに形成された焦点測
定用面と、上記光スポットの焦点が前記情報記録面上に
あるときの上記焦点測定用面からの反射光量をホールド
し、かつそのホールドした反射光量と焦点測定用面から
の反射光量とで焦点ずれを検出する信号処理回路とを備
えたことを特徴とする光ヘッドの焦点ずれ検出装置。1. An optical fiber that emits a laser beam from one end, an optical imaging means for imaging the laser beam as a light spot on the information recording surface of the optical disk, and an optical fiber provided at the other end of the optical fiber. a photodetector for detecting the amount of light reflected through the fiber;
and a focus measurement surface formed to have a size larger than the diameter of the light spot, and holding the amount of light reflected from the focus measurement surface when the focus of the light spot is on the information recording surface, and holding the amount of light reflected from the focus measurement surface when the focus of the light spot is on the information recording surface. What is claimed is: 1. A defocus detection device for an optical head, comprising: a signal processing circuit that detects defocus based on the amount of reflected light from the reflected light amount and the amount of reflected light from a focus measurement surface.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP6063989A JPH02240837A (en) | 1989-03-15 | 1989-03-15 | Defocus detector for optical head |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP6063989A JPH02240837A (en) | 1989-03-15 | 1989-03-15 | Defocus detector for optical head |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH02240837A true JPH02240837A (en) | 1990-09-25 |
Family
ID=13148089
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP6063989A Pending JPH02240837A (en) | 1989-03-15 | 1989-03-15 | Defocus detector for optical head |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH02240837A (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR100708097B1 (en) * | 2000-07-24 | 2007-04-16 | 삼성전자주식회사 | Optical recoding and/or reproducing apparatus using swing arm actuator and Optical disc adopting thereof |
-
1989
- 1989-03-15 JP JP6063989A patent/JPH02240837A/en active Pending
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR100708097B1 (en) * | 2000-07-24 | 2007-04-16 | 삼성전자주식회사 | Optical recoding and/or reproducing apparatus using swing arm actuator and Optical disc adopting thereof |
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