JPH05266502A - Optical head for optical disk device - Google Patents
Optical head for optical disk deviceInfo
- Publication number
- JPH05266502A JPH05266502A JP4065410A JP6541092A JPH05266502A JP H05266502 A JPH05266502 A JP H05266502A JP 4065410 A JP4065410 A JP 4065410A JP 6541092 A JP6541092 A JP 6541092A JP H05266502 A JPH05266502 A JP H05266502A
- Authority
- JP
- Japan
- Prior art keywords
- optical
- optical disk
- light
- reflected
- laser
- 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.)
- Pending
Links
Landscapes
- Optical Recording Or Reproduction (AREA)
- Optical Head (AREA)
Abstract
Description
【0001】[0001]
【産業上の利用分野】この発明は、携帯用ディスクプレ
−ヤ−など、特に小型化,軽量化,および低価格化が求
められる光ディスク装置の光ヘッドに関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical head for an optical disk device, such as a portable disk player, which is particularly required to be compact, lightweight and inexpensive.
【0002】[0002]
【従来の技術】携帯用ディスクプレ−ヤ−の光ヘッド
は、レ−ザ−ダイオ−ドが発するレ−ザ−光を光ディス
クの情報記憶面(ピット面)に集光させ、ピット面で反
射した回析光をホトダイオ−ドで電気信号に変換して記
録情報の読出し,焦点誤差の検出などを行うものであ
り、その軽量化,低価格化のために光学系の部品点数の
削減,部品の小型化などが進められている。2. Description of the Related Art An optical head of a portable disk player focuses laser light emitted by a laser diode on an information storage surface (pit surface) of an optical disk and reflects it on the pit surface. The diffracted light is converted into an electric signal by a photo diode to read recorded information and detect a focus error. To reduce the weight and cost of the optical system, the number of parts of the optical system is reduced. Are being miniaturized.
【0003】図2は簡素化された従来の光ヘッドを模式
化して示す構成図であり、レ−ザ−ダイオ−ド1から放
射されて発散するレ−ザ−光11直線回析格子を通り、
レ−ザ−光11の光軸11Aに対して45°の傾きを有
する平行平板ガラス3の表面を第1の反射面3Aとして
90°方向を変え、凸レンズ(対物レンズとも呼ぶ)4
で集束され、その光軸11Bに直交する方向に配された
光ディスク5の情報記憶面(以下ピット面とよぶ)5P
上に微小光スポット12となって投射される。また、凸
レンズ4は図示しないサ−ボ機構により駆動される光軸
調整機構9に支持され、ピット面5Pにおける合焦制御
や、情報トラックに光スポット12を移動させ,位置決
めするトラッキング制御などが行われる。FIG. 2 is a schematic diagram showing a simplified conventional optical head, which passes through a laser light 11 linear diffraction grating radiated and diverged from a laser diode 1. ,
The surface of the parallel plate glass 3 having an inclination of 45 ° with respect to the optical axis 11A of the laser light 11 is used as the first reflecting surface 3A to change the direction of 90 °, and a convex lens (also called an objective lens) 4
The information storage surface (hereinafter referred to as a pit surface) 5P of the optical disk 5 which is focused by the optical disk 11 and is arranged in a direction orthogonal to the optical axis 11B.
It is projected as a minute light spot 12 on the upper side. The convex lens 4 is supported by an optical axis adjusting mechanism 9 driven by a servo mechanism (not shown) to perform focusing control on the pit surface 5P and tracking control for moving and positioning the light spot 12 on the information track. Be seen.
【0004】一方、ピット面5Pで反射され情報の記憶
状態や合焦状態等の情報を含む回析光は、平行平板ガラ
ス3を透過することにより非点収差が付与された検出光
15となりホトダイオ−ド6に入射して電気信号に変換
される。ここで、ホトダイオ−ド6を4分割ホトダイオ
−ド対とし、光スポット12がピット面5P上に合焦し
たとき、光軸15Aを中心とする検出光15の光束分布
の断面形状が円形となる位置に配置すれば、各分割ホト
ダイオ−ド6A,6B,6C,および6Dの出力電気信
号の和からピット面の記憶情報を読み出すことができ
る。また、微小光スポット12の合焦位置がピット面5
Pからずれると、ピット面に対する合焦点の遠近に応じ
てホトダイオ−ド6上における検出光15の光束分布が
光軸15Aを中心に互いに直交する楕円となる。そこ
で、ホトダイオ−ド6を互いに直交する楕円の長径方向
に対して45°ずれた直線で4分割しておけば、光軸1
5Aに対して対称な分割ホトダイオ−ド対の出力電気信
号の和(6A+6C)と(6B+6D)との間に差が生
ずるので、この信号の差を焦点誤差信号として前記サ−
ポ機構を駆動することにより、いわゆる非点収差法によ
る合焦制御を行うことができる。On the other hand, the diffracted light reflected by the pit surface 5P and containing the information such as the information storage state and the focused state is transmitted through the parallel flat plate glass 3 to become the detection light 15 to which the astigmatism is added, thereby becoming a photodiode. -It is incident on the terminal 6 and is converted into an electric signal. Here, when the photo diode 6 is a 4-division photo diode pair and the light spot 12 is focused on the pit surface 5P, the cross-sectional shape of the luminous flux distribution of the detection light 15 around the optical axis 15A becomes circular. If it is arranged at the position, the stored information on the pit surface can be read from the sum of the output electric signals of the respective divided photodiodes 6A, 6B, 6C and 6D. Also, the focus position of the small light spot 12 is the pit surface 5.
When deviated from P, the luminous flux distribution of the detection light 15 on the photo diode 6 becomes an ellipse orthogonal to each other with the optical axis 15A as the center, depending on the distance of the focal point to the pit surface. Therefore, if the photo diode 6 is divided into four parts by straight lines that are offset by 45 ° with respect to the major axis directions of the ellipses orthogonal to each other, the optical axis 1
Since there is a difference between the sum (6A + 6C) and (6B + 6D) of the output electric signals of the pair of divided photodiodes that are symmetric with respect to 5A, the difference between these signals is used as the focus error signal for the servo signal.
By driving the Po mechanism, focusing control by the so-called astigmatism method can be performed.
【0005】[0005]
【発明が解決しようとする課題】上述の簡素化された従
来の光ヘッドにおいては、レ−ザ−ダイオ−ド1,直線
回析格子2,平行平板ガラス3および凸レンズ4で構成
される光の投射系が、レ−ザ−光11を平行光にするた
めのコリメ−トレンズやビ−ム整形用レンズ、あるいは
検出光を投射系から分岐するためのビ−ムスプリッタな
どを含まず、また検出系がホトダイオ−ド6のみで構成
されて光学部品を含まないので、光ヘッドの光学部品点
数が上記各光学部品を含む従来の光ヘッドに比べて大幅
に減少し、光ディスク装置ことに光ディスクプレ−ヤ−
を軽量化,低価格化することができる。一方、光ディス
クプレ−ヤ−の外形寸法の内、長い2辺の寸法は光ディ
スクの大きさによって決まってしまうため、その小型化
は短い2辺(厚み)を縮小して外形寸法を偏平化し,容
積を減らすことが課題となる。In the simplified conventional optical head described above, the light composed of the laser diode 1, the linear diffraction grating 2, the parallel plate glass 3 and the convex lens 4 is used. The projection system does not include a collimating lens or a beam shaping lens for collimating the laser light 11 or a beam splitter for branching the detection light from the projection system, and the detection is performed. Since the system is composed of only the photo diode 6 and does not include optical parts, the number of optical parts of the optical head is significantly reduced as compared with the conventional optical head including the above-mentioned optical parts, and the optical disk device and the optical disk pre-recorder. Yar
Can be made lighter and less expensive. On the other hand, of the external dimensions of the optical disc player, the dimensions of the two long sides are determined by the size of the optical disc. Therefore, miniaturization reduces the short two sides (thickness) to flatten the external dimensions and increase the volume. The challenge is to reduce
【0006】ところが、従来の光ヘッドでは、検出系に
おける検出光15の光軸15Aが光ディスク5の情報記
憶面5Pに対して垂直な方向であるため、ホトダイオ−
ド6と光ディスク5との間の距離が長くなり、これが光
ディスクプレ−ヤ−の厚み方向の寸法の縮小を阻害する
という欠点がある。また、検出光15を図2において紙
面に垂直な方向に90°変えるよう構成すれば、光ディ
スクプレィヤ−の厚み方向の寸法を縮小して小型化でき
ると期待されるが、この方法は光路を90°変更するた
めの光学部品の追加を必要とするため、軽量化,低価格
化を阻害するという問題が発生する。However, in the conventional optical head, since the optical axis 15A of the detection light 15 in the detection system is perpendicular to the information storage surface 5P of the optical disk 5, the photodiode
There is a drawback that the distance between the disk 6 and the optical disk 5 becomes long, which hinders the reduction of the dimension of the optical disk player in the thickness direction. Further, if the detection light 15 is configured to be changed by 90 ° in the direction perpendicular to the paper surface in FIG. 2, it is expected that the dimension of the optical disc player in the thickness direction can be reduced and downsized. Since it is necessary to add an optical component for changing the angle by 90 °, there arises a problem that the reduction in weight and the reduction in price are hindered.
【0007】この発明の目的は、部品点数を増すことな
く検出光の光路を変更でき、光ディスク装置の外形寸法
をその厚み方向に縮小可能な光ヘッドを得ることにあ
る。An object of the present invention is to obtain an optical head which can change the optical path of the detection light without increasing the number of parts and can reduce the outer dimensions of the optical disk device in its thickness direction.
【0008】[0008]
【課題を解決するための手段】上記課題を解決するため
に、この発明によれば、レ−ザ−ダイオ−ドの出射レ−
ザ−光を直線回析格子を通して平行平板ガラスの表面を
第1の反射面として光ディスク方向に光路を変更させ、
この光路上に配された凸レンズでレ−ザ−光を集束して
前記光ディスクの情報記憶面に微小光スポットとして投
射する投射系を含むものにおいて、前記平行平板ガラス
が第1の反射面に対向する面に第2の反射面を備え、前
記光ディスクの情報記憶面で反射された回析光を前記第
2の反射面で反射させることにより非点収差が付与され
た検出光を、前記レ−ザ−ダイオ−ドの出射レ−ザ−光
の光軸に対して所定の間隔を保持して平行な方向に出射
するよう形成されてなるものとする。In order to solve the above-mentioned problems, according to the present invention, an emission laser of a laser diode is used.
The light is passed through a linear diffraction grating to change the optical path toward the optical disc with the surface of the parallel plate glass as the first reflecting surface.
In a projection system in which a laser beam is focused by a convex lens arranged on the optical path and projected as a minute light spot on the information storage surface of the optical disk, the parallel flat glass faces the first reflection surface. A second reflecting surface on the surface of the optical disc, and diffracted light reflected by the information storage surface of the optical disc is reflected by the second reflecting surface to detect the detection light with astigmatism. It is assumed that the laser diode is formed so as to be emitted in a direction parallel to the optical axis of the emitted laser light of the laser diode at a predetermined interval.
【0009】また、凸レンズにより光ディスクの情報記
録面に微小光スポットが合焦したとき、検出光の光束分
布が円形となる位置にホトダイオ−ドを備えてなるもの
とする。さらに、ホトダイオ−ドが4分割ホトダイオ−
ド対からなり、反射光の非点収差に基づき凸レンズの焦
点誤差を検出するよう形成されてなるものとする。It is also assumed that a photo diode is provided at a position where the luminous flux distribution of the detection light becomes circular when a minute light spot is focused on the information recording surface of the optical disk by the convex lens. Furthermore, the photodiode is divided into four photodiodes.
It is assumed that the focus error of the convex lens is detected based on the astigmatism of the reflected light.
【0010】[0010]
【作用】この発明の構成において、レ−ザ−ダイオ−ド
からのレ−ザ−光を光ディスク方向に光路変更する平行
平板ガラスに、その第1の反射面に対向する第2の反射
面を設け、光ディスクの情報記憶面で反射された回析光
を第2の反射面で反射させることにより非点収差が付与
された検出光を、レ−ザ−ビ−ムの光軸に対して所定の
間隔を保持して平行な方向に出射するよう構成したこと
により、平行平板ガラスに第2の反射面を設けるだけの
簡単な構造変更で、従来光ディスクに対して垂直であっ
た検出光の光路をレ−ザ−光に平行な方向に90°変え
ることが可能となり、平行平板ガラス以遠の容積が削減
された偏平な光ヘッドが得られるので、光学部品点数を
増すことなく光ヘッドを薄型化する機能が得られる。In the structure of the present invention, the parallel flat plate glass for changing the optical path of the laser light from the laser diode in the optical disc direction is provided with the second reflecting surface facing the first reflecting surface. The diffracted light reflected by the information storage surface of the optical disk is reflected by the second reflecting surface to detect the detection light to which astigmatism is given, with respect to the optical axis of the laser beam. The optical path of the detection light that was perpendicular to the conventional optical disc can be changed by a simple structure change such that the second reflection surface is provided on the parallel flat glass by arranging the light beams to be emitted in the parallel direction while maintaining the interval. Can be changed by 90 ° in the direction parallel to the laser light, and a flat optical head with a volume smaller than that of parallel flat glass can be obtained, so the optical head can be made thinner without increasing the number of optical components. The function to do is obtained.
【0011】また、凸レンズにより光ディスクの情報記
録面に微小光スポットが合焦したとき、検出光の光束分
布が円形となる位置にホトダイオ−ドを設けるよう構成
すれば、ホトダイオ−ドをレ−ザ−ダイオ−ドに近接配
置してレ−ザ−光および検出光の光路を一体化し、その
スペ−スを最小限に縮小できるので、縮小されたスペ−
スを合理的な部品配置スペ−スとして有効に利用するこ
とにより、光ヘッドおよびこれを収納する光ディスク装
置の外形寸法の偏平化を容易化する機能が得られる。さ
らに、ホトダイオ−ドを4分割ホトダイオ−ド対とする
ことにより、小型化された光ヘッドに非点収差法に基づ
く焦点誤差信号の検出機能を持たせることができる。Further, when the microlens spot is focused on the information recording surface of the optical disk by the convex lens, the photodiode may be provided at a position where the luminous flux distribution of the detection light becomes circular. -The space between the laser light and the detection light can be integrated by arranging them close to the diode, and the space between them can be reduced to a minimum.
By effectively using the space as a rational component placement space, a function of facilitating flattening of the outer dimensions of the optical head and the optical disk device that houses the optical head can be obtained. Furthermore, by making the photo diode a 4-division photo diode pair, the miniaturized optical head can be provided with the function of detecting the focus error signal based on the astigmatism method.
【0012】[0012]
【実施例】以下、この発明を実施例に基づいて説明す
る。図1はこの発明の実施例になる光ディスク装置の光
ヘッドを模式化して示す構成図であり、従来技術と同じ
構成部分には同一参照符号を付すことにより、重複した
説明を省略する。図において、平行平板ガラス23は、
第1の反射面23Aを有する平行平板ガラスの第1の反
射面に対向する面に反射膜をコ−ティングした第2の反
射面23Bが形成される。レ−ザ−ダイオ−ド1から放
射されて発散するレ−ザ−光11は直線回析格子2を通
り、レ−ザ−ビ−ム11の光軸11Aに対して45°の
傾きを有する平行平板ガラス23の表面を第1の反射面
23Aとして90°方向を変え、凸レンズ(対物レンズ
とも呼ぶ)4で集束され、その光軸11Bに光の入射面
が直交するように配された光ディスク5のピット面5P
上に微小光スポット12となって投射される。EXAMPLES The present invention will be described below based on examples. FIG. 1 is a schematic diagram schematically showing an optical head of an optical disk device according to an embodiment of the present invention. The same components as those of the conventional technique are designated by the same reference numerals, and a duplicate description will be omitted. In the figure, the parallel plate glass 23 is
A second reflecting surface 23B coated with a reflecting film is formed on the surface of the parallel flat plate glass having the first reflecting surface 23A facing the first reflecting surface. The laser light 11 emitted from the laser diode 1 and diverging passes through the linear diffraction grating 2 and has an inclination of 45 ° with respect to the optical axis 11A of the laser beam 11. An optical disk in which the surface of the parallel plate glass 23 is used as a first reflecting surface 23A, the direction of which is changed by 90 °, is converged by a convex lens (also referred to as an objective lens) 4, and the light incident surface is orthogonal to its optical axis 11B. 5P pit surface 5P
It is projected as a minute light spot 12 on the upper side.
【0013】また、ピット面5Pで反射され情報の記憶
状態や合焦状態等の情報を含む回析光は、凸レンズ4お
よび平行平板ガラス23の第1の反射面23Aを透過し
て第2の反射面23Bで反射し、再び第1の反射面から
検出光25となって出射する。このとき、平行平板背面
ミラ−23で非点収差が付与された検出光25の光軸2
5Aは、光が平行平板ガラス内を斜めに往復した分レ−
ザ−光11に対して平行移動することになり、レ−ザ−
光11の光軸11Aに対し、平行平板ガラスの屈折率や
厚みなどによって決まる所定の間隔dを保持して平行な
非点光線束となる。そこで、凸レンズ4の焦点制御によ
り光ディスク5の情報記憶面5Pに微小光スポット12
が合焦したとき、検出光25の光束分布が円形となる位
置に4分割ホトダイオ−ド対6を設けることにより、検
出光25を電気信号に変換して情報の読出しができると
ともに、非点収差法に基づいて焦点誤差信号の検出を行
うことができる。The diffracted light which is reflected by the pit surface 5P and contains information such as the information storage state and the focused state is transmitted through the convex lens 4 and the first reflecting surface 23A of the parallel flat plate glass 23, and the second The light is reflected by the reflecting surface 23B and again emitted as the detection light 25 from the first reflecting surface. At this time, the optical axis 2 of the detection light 25 to which the astigmatism is added by the parallel plate back surface mirror -23
5A shows the amount of light that the light obliquely travels back and forth in the parallel plate glass.
The laser beam 11 will move in parallel with the laser beam 11,
The astigmatic ray bundle is parallel to the optical axis 11A of the light 11 while maintaining a predetermined distance d determined by the refractive index and thickness of the parallel plate glass. Therefore, by controlling the focus of the convex lens 4, a small light spot 12 is formed on the information storage surface 5P of the optical disc 5.
When the focal point is in focus, the four-division photodiode pair 6 is provided at a position where the luminous flux distribution of the detection light 25 becomes circular, so that the detection light 25 can be converted into an electric signal to read information, and the astigmatism can be obtained. The focus error signal can be detected based on the method.
【0014】上述のように構成された光ディスク装置の
光ヘッドにおいては、平行平板ガラスの背面に第2の反
射面を形成するだけの簡単な構造変更により、従来光デ
ィスク面に垂直であった検出光15を、部品点数を増す
ことなくレ−ザ−光11に平行な検出光25に90°光
路変更できるので、従来平行平板ガラス3とホトダイオ
−ド6との間に必要とした空間距離が不要となり、その
分光ヘッドを偏平化して光ディスクプレ−ヤ−を小型化
することができる。また、4分割ホトダイオ−ド対6を
レ−ザ−ダイオ−ド1に近接配置してレ−ザ−光11お
よび検出光25の光路を一体化し、そのスペ−スを最小
限に縮小できるので、縮小されたスペ−スを合理的な部
品配置スペ−スとして有効に利用することにより、光ヘ
ッドおよびこれを収納する光ディスク装置の外形寸法の
薄型化を無理なく達成できる利点が得られる。In the optical head of the optical disk device configured as described above, the detection light which has been perpendicular to the optical disk surface in the past is changed by a simple structure change such that the second reflecting surface is formed on the back surface of the parallel plate glass. Since the optical path of 15 can be changed by 90 ° to the detection light 25 parallel to the laser light 11 without increasing the number of components, the space distance required between the parallel flat plate glass 3 and the photo diode 6 in the past is unnecessary. Therefore, the spectroscopic head can be flattened to reduce the size of the optical disc player. Further, the four-divided photodiode pair 6 is arranged close to the laser diode 1 to integrate the optical paths of the laser light 11 and the detection light 25, and the space thereof can be reduced to a minimum. By effectively using the reduced space as a rational component arrangement space, it is possible to obtain an advantage that the outer dimensions of the optical head and the optical disk device that houses the optical head can be reasonably thinned.
【0015】[0015]
【発明の効果】この発明は前述のように、レ−ザ−ダイ
オ−ドからのレ−ザ−光を光ディスク方向に光路変更す
る平行平板ガラスに、第1の反射面に対向する第2の反
射面を設け、光ディスクの情報記憶面で反射された回析
光を第2の反射面で反射させるよう構成した。その結
果、従来光ディスク面に直交する方向であった検出光を
レ−ザ−光に平行な方向に90°光路変更する機能を部
品点数を増加させることなく達成でき、これにより光ヘ
ッドを偏平化できるので、薄型化された光ディスク装
置,ことに光ディスクプレ−ヤ−を提供することができ
る。また、4分割ホトダイオ−ド対をレ−ザ−ダイオ−
ド1に近接配置してレ−ザ−ビ−ムおよび検出光の光路
を一体化し、そのスペ−スを最小限に縮小できるので、
縮小されたスペ−スを合理的な部品配置スペ−スとして
有効に利用することにより、光ヘッドおよびこれを収納
する光ディスク装置の外形寸法の薄型化を無理なく達成
できる利点が得られる。As described above, according to the present invention, the parallel plate glass for changing the optical path of the laser light from the laser diode in the optical disc direction is provided with the second flat plate facing the first reflecting surface. A reflecting surface is provided so that the diffracted light reflected by the information storage surface of the optical disk is reflected by the second reflecting surface. As a result, it is possible to achieve the function of changing the optical path of the detection light in the direction perpendicular to the optical disk surface by 90 ° in the direction parallel to the laser light without increasing the number of parts, and thereby flattening the optical head. Therefore, it is possible to provide a thinned optical disk device, especially an optical disk player. Also, a four-division photodiode pair is set as a laser diode.
Since the laser beam and the optical path of the detection light are integrated by arranging them in close proximity to the terminal 1 and the space thereof can be reduced to a minimum,
By effectively utilizing the reduced space as a rational space for arranging parts, it is possible to obtain an advantage that the outer dimensions of the optical head and the optical disk device accommodating the space can be reasonably thinned.
【図1】この発明の実施例になる光ディスク装置の光ヘ
ッドを模式化して示す構成図FIG. 1 is a configuration diagram schematically showing an optical head of an optical disk device according to an embodiment of the present invention.
【図2】簡素化された従来の光ヘッドを模式化して示す
構成図FIG. 2 is a configuration diagram schematically showing a simplified conventional optical head.
1 レ−ザ−ダイオ−ド 2 直線回析格子 3 平行平板ガラス 3A 第1の反射面 4 凸レンズ(対物レンズ) 5 光ディスク 5P 情報記憶面(ピット面) 6 ホトダイオ−ド(4分割ホトダイオ−ド対) 9 光軸調整機構 11 レ−ザ−光(レ−ザ−ダイオ−ドの出射光) 11A レ−ザ−光の光軸 12 微小光スポット(合焦点) 15 検出光 15A 検出光の光軸 23 平行平板ガラス(第2の反射面付) 23A 第1の反射面 23B 第2の反射面 25 検出光 25A 検出光の光軸 1 Laser Diode 2 Linear Diffraction Grating 3 Parallel Flat Glass 3A First Reflecting Surface 4 Convex Lens (Objective Lens) 5 Optical Disk 5P Information Storage Surface (Pit Surface) 6 Photodiode (4 Division Photodiode Pair) ) 9 optical axis adjusting mechanism 11 laser light (light emitted from laser diode) 11A optical axis of laser light 12 microscopic light spot (focus point) 15 detection light 15A optical axis of detection light 23 Parallel Flat Glass (with Second Reflecting Surface) 23A First Reflecting Surface 23B Second Reflecting Surface 25 Detection Light 25A Optical Axis of Detection Light
Claims (3)
線回析格子を通して平行平板ガラスの表面を第1の反射
面として光ディスク方向に光路を変更させ、この光路上
に配された凸レンズでレ−ザ−光を集束して前記光ディ
スクの情報記憶面に微小光スポットとして投射する投射
系を含むものにおいて、前記平行平板ガラスが第1の反
射面に対向する面に第2の反射面を備え、前記光ディス
クの情報記憶面で反射された回析光を第2の反射面で反
射させることにより非点収差が付与された検出光を、前
記レ−ザ−ダイオ−ドの出射レ−ザ−光の光軸に対して
所定の間隔を保持して平行な方向に出射するよう形成さ
れてなることを特徴とする光ディスク装置の光ヘッド。1. The laser light emitted from a laser diode is passed through a linear diffraction grating to change the optical path in the optical disc direction with the surface of a parallel plate glass as the first reflecting surface, and is distributed on this optical path. A projection system for converging laser light by a convex lens which is projected and projecting it as a minute light spot on the information storage surface of the optical disk, wherein the parallel flat glass plate has a second surface on a surface facing the first reflection surface. Of the laser light, the diffracted light reflected by the information storage surface of the optical disk is reflected by the second reflective surface to detect the astigmatism. An optical head of an optical disk device, characterized in that it is formed so as to be emitted in a direction parallel to the optical axis of the emission laser light while maintaining a predetermined interval.
微小光スポットが合焦したとき、検出光の光束分布が円
形となる位置にホトダイオ−ドを備えてなることを特徴
とする請求項1記載の光ディスク装置の光ヘッド。2. A photodiode is provided at a position where the luminous flux distribution of the detection light becomes circular when a minute light spot is focused on the information recording surface of the optical disk by the convex lens. Optical head for optical disk drive.
からなり、反射光の非点収差に基づき凸レンズの焦点誤
差を検出するよう形成されてなることを特徴とする請求
項2記載の光ディスク装置の光ヘッド。3. The optical disk apparatus according to claim 2, wherein the photo diode is composed of a 4-division photo diode pair, and is formed so as to detect the focus error of the convex lens based on the astigmatism of the reflected light. Light head.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP4065410A JPH05266502A (en) | 1992-03-24 | 1992-03-24 | Optical head for optical disk device |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP4065410A JPH05266502A (en) | 1992-03-24 | 1992-03-24 | Optical head for optical disk device |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH05266502A true JPH05266502A (en) | 1993-10-15 |
Family
ID=13286239
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP4065410A Pending JPH05266502A (en) | 1992-03-24 | 1992-03-24 | Optical head for optical disk device |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH05266502A (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2755283A1 (en) * | 1996-10-28 | 1998-04-30 | Daewoo Electronics Co Ltd | Optical disc reader system with knife edge focus control |
-
1992
- 1992-03-24 JP JP4065410A patent/JPH05266502A/en active Pending
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2755283A1 (en) * | 1996-10-28 | 1998-04-30 | Daewoo Electronics Co Ltd | Optical disc reader system with knife edge focus control |
US6021105A (en) * | 1996-10-28 | 2000-02-01 | Daewoo Electronics Co., Ltd. | Knife edge method for use in an optical pickup system |
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