JPH0534732B2 - - Google Patents
Info
- Publication number
- JPH0534732B2 JPH0534732B2 JP59072440A JP7244084A JPH0534732B2 JP H0534732 B2 JPH0534732 B2 JP H0534732B2 JP 59072440 A JP59072440 A JP 59072440A JP 7244084 A JP7244084 A JP 7244084A JP H0534732 B2 JPH0534732 B2 JP H0534732B2
- Authority
- JP
- Japan
- Prior art keywords
- photodetector
- recording medium
- light
- optical recording
- photodetectors
- 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 - Lifetime
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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
Landscapes
- Automatic Focus Adjustment (AREA)
- Optical Recording Or Reproduction (AREA)
Description
【発明の詳細な説明】
産業上の利用分野
本発明は、光学式記録媒体のフオーカシング状
態を検出する為のフオーカス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 focus detection device for detecting the focusing state of an optical recording medium.
背景技術とその問題点
第１図及び第２図は、上記の様なフオーカス検
出装置の１つの従来例を示している。この従来例
は、光デイスクプレーヤに於いて光デイスクのフ
オーカシング状態を検出する為のものである。BACKGROUND ART AND PROBLEMS THEREOF FIGS. 1 and 2 show one conventional example of the focus detection device as described above. This conventional example is for detecting the focusing state of an optical disc in an optical disc player.
レーザダイオード等の光源１から射出された光
の内で所定の偏光面を有する直線偏光のみが偏光
ビームスプリツタ２を透過し、この直線偏光がコ
リメートレンズ３によつて平行光とされる。 Of the light emitted from a light source 1 such as a laser diode, only linearly polarized light having a predetermined plane of polarization is transmitted through a polarizing beam splitter 2, and this linearly polarized light is converted into parallel light by a collimating lens 3.
この平行な直線偏光は、偏光ビームスプリツタ
２の光軸を中心として所定の角度に配置されてい
る1/4波長板４を透過して円偏光となる。そして
この平行な円偏光は、対物レンズ５によつて収束
されて、光デイスク６の記録面へ入射する。 This parallel linearly polarized light passes through a quarter-wave plate 4 arranged at a predetermined angle with respect to the optical axis of the polarizing beam splitter 2, and becomes circularly polarized light. This parallel circularly polarized light is then converged by the objective lens 5 and is incident on the recording surface of the optical disk 6.
光デイスク６の記録面で反射された円偏光は、
対物レンズ５によつて平行光とされる。この平行
な円偏光は、1/4波長板４を透過して、入射時の
直線偏光の偏光面とは直角な偏光面を有する直線
偏光となる。 The circularly polarized light reflected by the recording surface of the optical disk 6 is
The objective lens 5 converts the light into parallel light. This parallel circularly polarized light passes through the quarter-wave plate 4 and becomes linearly polarized light having a polarization plane perpendicular to the polarization plane of the incident linearly polarized light.
そしてこの平行な直線偏光は、コリメートレン
ズ３によつて収束され、更に入射時とは逆に偏光
ビームスプリツタ２によつて反射されて、光検出
器７へ入射する。 The parallel linearly polarized light is converged by the collimator lens 3, and further reflected by the polarizing beam splitter 2 in the opposite direction to the incident state, and is incident on the photodetector 7.
第２図は、光検出器７を示している。この光検
出器７は、光デイスク６のトラツク方向に対応し
ているＴ方向へ３分割され更にこのＴ方向に直角
な方向へ２分割されている合計６個の光検出部
A1〜Ｄを有している。 FIG. 2 shows the photodetector 7. FIG. This photodetector 7 is divided into three in the T direction corresponding to the track direction of the optical disk 6, and further divided into two in a direction perpendicular to the T direction, making up a total of six photodetectors.
It has A 1 to D.
光検出器７上には、光デイスク６からの上述の
反射光によつてスポツトＳが形成されるが、この
スポツトＳは、対物レンズ５と光デイスク６とが
離間すれば大きくなり、接近すれば小さくなる。 A spot S is formed on the photodetector 7 by the above-mentioned reflected light from the optical disk 6, but this spot S becomes larger when the objective lens 5 and the optical disk 6 are separated from each other, and becomes larger when they approach each other. It gets smaller.
従つて、各々の光検出部A1〜Ｄで得られる検
出信号から（Ａ＋Ｂ）−（Ｃ＋Ｄ）を求めれば、こ
の値が第３図に示す様な対物レンズ５と光デイス
ク６との距離つまり光デイスク６のフオーカシン
グ状態を示すフオーカス誤差信号となる。 Therefore, if (A+B)-(C+D) is calculated from the detection signals obtained from each of the photodetectors A1 to D, this value will be the distance between the objective lens 5 and the optical disk 6 as shown in FIG. This becomes a focus error signal indicating the focusing state of the optical disc 6.
なお、第２図に示す様に光検出部Ｃ及びＤの夫
夫の受光面積を光検出部A1，A2及びB1，B2の
夫々の受光面積よりも小さくすることによつて、
（Ａ＋Ｂ）と（Ｃ＋Ｄ）との差であるフオーカス
誤差信号を大きくする様にしている。 In addition, as shown in FIG. 2, by making the light-receiving area of the husband and wife of the photodetectors C and D smaller than the light-receiving area of each of the photodetectors A 1 , A 2 and B 1 , B 2 ,
The focus error signal, which is the difference between (A+B) and (C+D), is increased.
また、（Ａ＋Ｃ）−（Ｂ＋Ｄ）の値を求めれば、
この値がプツシユプル法によるトラツキング誤差
信号となる。 Also, if you find the value of (A+C)-(B+D),
This value becomes the tracking error signal by the push-pull method.
ところが、上述の様にして求めたフオーカス誤
差信号の波形は、第３図から明らかな様に、ゼロ
クロス点に関して対称ではない為にこのゼロクロ
ス点近傍に於ける直線性が悪く、この結果、フオ
ーカス制御を正確且つ安定的に行うことはできな
い。 However, as is clear from Fig. 3, the waveform of the focus error signal obtained as described above is not symmetrical with respect to the zero-crossing point, so the linearity near this zero-crossing point is poor, and as a result, focus control cannot be performed accurately and stably.
また、光デイスク６からの反射光によるスポツ
トＳは、光デイスク６のピツトによる高次の回折
光の為に、その全体に亘つて強度が均一であると
いうわけではなく、第４図に示す様に、空間周波
数が高い場合はスポツトＳの周辺部が強く、空間
周波数が低い場合は逆に中央部が強い。 Furthermore, the intensity of the spot S caused by the reflected light from the optical disk 6 is not uniform over the entire area because it is a high-order diffracted light due to the pits of the optical disk 6, as shown in FIG. In other words, when the spatial frequency is high, the periphery of the spot S is strong, and when the spatial frequency is low, the center is strong.
従つて、スポツトＳの周辺部と中央部との強度
の差である（Ａ＋Ｂ）−（Ｃ＋Ｄ）をフオーカス誤
差信号とすれば、光デイスク６の空間周波数によ
つては、実際にはフオーカス誤差が無いにも拘ら
ず、フオーカス誤差が有るとみなされてしまうの
で、このことによつてもフオーカス制御を正確に
行うことができない。 Therefore, if (A+B)-(C+D), which is the difference in intensity between the periphery and the center of the spot S, is the focus error signal, depending on the spatial frequency of the optical disk 6, the focus error may actually be Even though there is no focus error, it is assumed that there is a focus error, and therefore focus control cannot be performed accurately.
発明の目的
本発明は、これらの問題点に鑑み、正確且つ安
定的なフオーカス制御が可能なフオーカス誤差信
号を得ることができるフオーカス検出装置を提供
することを目的としている。OBJECTS OF THE INVENTION In view of these problems, an object of the present invention is to provide a focus detection device that can obtain a focus error signal that enables accurate and stable focus control.
発明の概要
本発明に係るフオーカス検出装置は、光学式記
録媒体からの反射光を２つの光線束に分割し、反
射光の収束点よりも光学式記録媒体から離間した
位置に第１の光検出器を配すると共に、反射光の
収束点よりも光学式記録媒体に近接した位置に第
２の光検出器を配し、第１の光検出器の周辺部に
よる検出信号及び第２の光検出器の中央部による
検出信号の和と第１の光検出器の中央部による検
出信号及び第２の光検出器の周辺部による検出信
号の和とを比較することによつて、フオーカス誤
差信号を得る様にしたものである。Summary of the Invention A focus detection device according to the present invention splits reflected light from an optical recording medium into two beam bundles, and detects a first light beam at a position farther from the optical recording medium than the convergence point of the reflected light. At the same time, a second photodetector is placed at a position closer to the optical recording medium than the convergence point of the reflected light, and a detection signal from the peripheral area of the first photodetector and a second photodetection are detected. The focus error signal is determined by comparing the sum of the detection signals from the central part of the detector with the sum of the detection signals from the central part of the first photodetector and the detection signals from the peripheral part of the second photodetector. This is what I did to get it.
実施例
以下、本発明の第１及び第２実施例を、第５図
〜第８図を参照しながら説明する。Embodiments Hereinafter, first and second embodiments of the present invention will be described with reference to FIGS. 5 to 8.
第５図〜第７図は、本発明の第１実施例を示し
ている。この第１実施例は、光検出器７の代りに
ビームスプリツタ１１が配されており、このビー
ムスプリツタ１１によつて分割された第１の光線
束の軸上で且つこの第１の光線束の収束点O1よ
りも光デイスク６から離間して第１の光検出器１
２が配されると共に、ビームスプリツタ１１によ
つて分割された第２の光線束の軸上で且つこの第
２の光線束の収束点O2よりも光デイスク６に近
接して第２の光検出器１３が配されており、更に
これら第１及び第２の光検出器１２，１３が、第
６図Ａ，Ｂに示す様に、光デイスク６のトラツク
に対応しているＴ方向へ３分割されている光検出
部A1，Ｃ，A2及びB1，Ｄ，B2を夫々有している
ことを除いて、第１図に示した実施例と実質的に
同様の構成であつてよい。 5 to 7 show a first embodiment of the present invention. In this first embodiment, a beam splitter 11 is arranged in place of the photodetector 7, and on the axis of the first beam split by the beam splitter 11 and on the axis of the first beam split by the beam splitter 11. The first photodetector 1 is located further away from the optical disk 6 than the convergence point O 1 of the bundle.
A second optical disc 6 is arranged on the axis of the second beam split by the beam splitter 11 and closer to the optical disk 6 than the convergence point O2 of the second beam. A photodetector 13 is arranged, and these first and second photodetectors 12, 13 are arranged in the T direction corresponding to the track of the optical disk 6, as shown in FIGS. 6A and 6B. It has substantially the same configuration as the embodiment shown in FIG. 1, except that it has three divided photodetecting sections A 1 , C, A 2 and B 1 , D, B 2 respectively. It's good to be warm.
光検出器１２，１３上には、ビームスプリツタ
１１で分割された第１及び第２の光線束によつ
て、第６図Ａ，Ｂに示す様に、スポツトS1及びS2
が夫々形成される。 As shown in FIGS. 6A and 6B, spots S 1 and S 2 are formed on the photodetectors 12 and 13 by the first and second beams split by the beam splitter 11.
are formed respectively.
第１の光検出器１２上に形成されるスポツトS1
は、第２図に示したスポツトＳと同様に、対物レ
ンズ５と光デイスク６とが離間すれば大きくな
り、接近すれば小さくなる。 Spot S 1 formed on the first photodetector 12
Similar to the spot S shown in FIG. 2, the distance between the objective lens 5 and the optical disk 6 increases as they move apart, and decreases as they approach each other.
従つて、各々の光検出部A1，A2，Ｃで得られ
る検出信号から（Ａ−Ｃ）を求めれば、この値は
上述の従来例に於ける（Ａ＋Ｂ）−（Ｃ＋Ｄ）と同
様に光検出器１２の周辺部による検出信号から中
央部による検出信号を減じたものであるので、
（Ａ−Ｃ）の波形は、第７図の一点鎖線で示す様
に、第３図に示した従来例のフオーカス誤差信号
と同様な波形となる。 Therefore, if (A-C) is calculated from the detection signals obtained from each of the photodetectors A 1 , A 2 , and C, this value is the same as (A+B)-(C+D) in the conventional example described above. Since it is obtained by subtracting the detection signal from the central part from the detection signal from the peripheral part of the photodetector 12,
The waveform (A-C), as shown by the dashed line in FIG. 7, is similar to the focus error signal of the conventional example shown in FIG.
一方、第２の光検出器１３上に形成されるスポ
ツトS2は、スポツトS1とは逆に、対物レンズ５と
光デイスク６とが離間すれど小さくなり、接近す
れば大きくなる。 On the other hand, the spot S2 formed on the second photodetector 13, contrary to the spot S1 , becomes smaller when the objective lens 5 and the optical disk 6 are separated from each other, and becomes larger when they approach each other.
従つて、（Ａ−Ｃ）とは逆に、光検出部１３の
中央部による検出信号から周辺部による検出信号
を減じたものである（Ｄ−Ｂ）を求めれば、この
（Ｄ−Ｂ）の波形は、第７図の点線で示す様に、
（Ａ−Ｃ）の波形を距離及び信号量を示す夫々の
軸について反転させた波形となる。 Therefore, contrary to (A-C), if (D-B) is obtained by subtracting the detection signal from the peripheral part from the detection signal from the central part of the photodetector 13, then this (D-B) As shown by the dotted line in Figure 7, the waveform of
This waveform is obtained by inverting the waveform (A-C) with respect to the respective axes indicating distance and signal amount.
この結果、双方の光検出器１２，１３の検出信
号から（Ａ−Ｃ）＋（Ｄ−Ｂ）を求めてこの信号を
フオーカス誤差信号とすれば、このフオーカス誤
差信号の波形は、第７図の実線で示す様に、ゼロ
クロス点に関して対称であり、このゼロクロス点
近傍に於ける直線性が非常に良い。 As a result, if (A-C)+(D-B) is obtained from the detection signals of both photodetectors 12 and 13 and this signal is used as a focus error signal, the waveform of this focus error signal is as shown in FIG. As shown by the solid line, it is symmetrical about the zero-crossing point, and the linearity near this zero-crossing point is very good.
また、（Ａ−Ｃ）と（Ｄ−Ｂ）とは共に光検出
器１２，１３の中央部による検出信号と周辺部に
よる検出信号との差であるが、（Ａ−Ｃ）＋（Ｄ−
Ｂ）は（Ａ＋Ｄ）−（Ｂ＋Ｃ）とも書け、この式の
第１項及び第２項は共に実質的には１つのスポツ
トの全体による信号を示している。この為に、フ
オーカス誤差信号全体としては、スポツトS1及び
S2内での強度の偏在の影響を受けない。 Moreover, (A-C) and (D-B) are both the difference between the detection signal from the central part of the photodetectors 12 and 13 and the detection signal from the peripheral part, but (A-C) + (D-
B) can also be written as (A+D)-(B+C), and both the first and second terms of this equation represent substantially the entire signal of one spot. Therefore, the focus error signal as a whole is
Not affected by uneven distribution of intensity within S 2 .
第８図は、本発明の第２実施例を示している。
この第２実施例は、ハーフミラー１４Ａと通常の
ミラー１４Ｂとを互いに平行に配置して第１及び
第２の光線束を互いに平行な方向へ分割する様に
したビームスプリツタ１４をビームスプリツタ１
１を代りに有することを除いて、第５図に示した
本発明の第１実施例と実質的に同様の構成であつ
てよい。 FIG. 8 shows a second embodiment of the invention.
This second embodiment uses a beam splitter 14 in which a half mirror 14A and a normal mirror 14B are arranged parallel to each other to split the first and second beams in directions parallel to each other. 1
1 instead of the first embodiment of the invention shown in FIG.
ビームスプリツタ１４を構成する材質の屈折率
をｎとし、ハーフミラー１４Ａと通常のミラー１
４Ｂとの間の光軸に沿う距離をｄとすると、第２
の光線束の収束点O2は、第１の光線束の収束点
O1に比べて第８図に示す様にビームスプリツタ
１４から更にΔz＝（１−１／ｎ）ｄだけ離間す
る。 The refractive index of the material composing the beam splitter 14 is n, and the half mirror 14A and the normal mirror 1 are
If the distance along the optical axis between 4B and 4B is d, then the second
The convergence point O 2 of the ray bundle is the convergence point of the first ray bundle
As shown in FIG. 8, compared to O 1 , it is further spaced apart from the beam splitter 14 by Δz=(1-1/n)d.
この様なビームスプリツタ１４を使用すると、
光デイスク６からの反射光の軸心に対するビーム
スプリツタ１４の角度を変更する場合でも、第１
及び第２の光検出器１２，１３を一体として移動
させればよいので、装置の信頼性が向上する。 When such a beam splitter 14 is used,
Even when changing the angle of the beam splitter 14 with respect to the axis of the reflected light from the optical disk 6, the first
Since it is only necessary to move the second photodetectors 12 and 13 as one unit, the reliability of the device is improved.
また、距離Δzを適当な値に設定すれば、第８
図に示す様に第１及び第２の光検出器１２，１３
を同一の平面内に配することができるので、装置
の構成が簡単になる。 Also, if the distance Δz is set to an appropriate value, the eighth
As shown in the figure, first and second photodetectors 12, 13
can be arranged in the same plane, which simplifies the configuration of the device.
なお、以上の第１及び第２実施例では、本発明
を共に光デイスクプレーヤに適用した場合につい
て述べたが、光デイスク以外の他の光学式記録媒
体を有する装置にも本発明を適用することができ
る。 In addition, in the above first and second embodiments, the case where the present invention is applied to both an optical disk player has been described, but the present invention can also be applied to a device having an optical recording medium other than an optical disk. I can do it.
発明の効果
上述の様に、本発明に係るフオーカス検出装置
によれば、波形がゼロクロス点に関して対称な為
にこのゼロクロス点近傍に於ける直線性がよいフ
オーカス誤差信号を得ることができるので、フオ
ーカス制御を正確且つ安定的に行うことができ
る。Effects of the Invention As described above, according to the focus detection device according to the present invention, since the waveform is symmetrical with respect to the zero-crossing point, it is possible to obtain a focus error signal with good linearity in the vicinity of the zero-crossing point. Control can be performed accurately and stably.
しかも、実質的には第１及び第２の光線束によ
るスポツトの全体同士を比較しているので、スポ
ツト内での強度の偏在による影響を受けないフオ
ーカス誤差信号を得ることができ、このことによ
つてもフオーカス制御を正確に行うことができ
る。 Furthermore, since the entire spot formed by the first and second beams of light is compared, it is possible to obtain a focus error signal that is not affected by uneven distribution of intensity within the spot. Focus control can be performed accurately even when the image is distorted.
第１図は本発明の一従来例を示す概略的な側面
図、第２図は第１図に示した一従来例で使用され
ている光検出器を示す概略的な正面図、第３図は
第１図に示した一従来例によつて得られるフオー
カス誤差信号を示すグラフ、第４図は第２図に示
した光検出器によつて得られる光の周波数と強度
との関係を示すグラフである。第５図は本発明の
第１実施例を示す概略的な側面図、第６図は第５
図に示した第１実施例で使用されている光検出器
を示す概略的な正面図、第７図は第５図に示した
第１実施例によつて得られるフオーカス誤差信号
を示すグラフ、第８図は本発明の第２実施例の一
部を示す概略的な側面図である。
なお図面に用いられている符号に於いて、６…
…光デイスク、１１，１４……ビームスプリツ
タ、Ｔ……トラツクに対応する方向、１２……第
１の光検出器、A1，A2，Ｃ……光検出部、O1…
…収束点、１３……第２の光検出器、B1，B2，
Ｄ……光検出部、O2……収束点である。
Fig. 1 is a schematic side view showing a conventional example of the present invention, Fig. 2 is a schematic front view showing a photodetector used in the conventional example shown in Fig. 1, and Fig. 3 is a schematic side view showing a conventional example of the present invention. is a graph showing the focus error signal obtained by the conventional example shown in Fig. 1, and Fig. 4 shows the relationship between the frequency and intensity of light obtained by the photodetector shown in Fig. 2. It is a graph. FIG. 5 is a schematic side view showing the first embodiment of the present invention, and FIG.
A schematic front view showing the photodetector used in the first embodiment shown in the figure, FIG. 7 is a graph showing a focus error signal obtained by the first embodiment shown in FIG. FIG. 8 is a schematic side view showing a part of a second embodiment of the present invention. Regarding the symbols used in the drawings, 6...
...Optical disk, 11, 14...Beam splitter, T...Direction corresponding to the track, 12...First photodetector, A1 , A2 , C...Photodetector, O1 ...
...Convergence point, 13...Second photodetector, B 1 , B 2 ,
D...Photodetection section, O2 ...Convergence point.
Claims (1)
れた状態で光学式記録媒体を照射しこの光学式記
録媒体によつて反射された光線束を２つの光線束
に分割する分割手段と、 前記光学式記録媒体によつて反射された前記光
線束の収束点よりも前記光学式記録媒体から離間
した位置に配されており、前記光学式記録媒体の
トラツクに対応する方向に並んでいる３個の光検
出部を有して、前記分割手段によつて分割された
２つの光線束の内の一方の光線束を受光する第１
の光検出器と、 前記光学式記録媒体によつて反射された前記光
線束の収束点よりも前記光学式記録媒体に近接し
た位置に配されており、前記光学式記録媒体のト
ラツクに対応する方向に並んでいる３個の光検出
部を有して、前記分割手段によつて分割された２
つの光線束の内の他方の光線束を受光する第２の
光検出器とを夫々具備し、 前記第１の光検出器に於ける両側の光検出部及
び前記第２の光検出器に於ける中央の光検出部の
夫々による検出信号の和と前記第１の光検出器に
於ける中央の光検出部及び前記第２の光検出器に
於ける両側の光検出部の夫々による検出信号の和
とを比較することによつて前記光学式記録媒体の
フオーカス誤差信号を得る様にしたフオーカス検
出装置。[Claims of Claims] 1. A division method in which a beam of light emitted from a light source and converged by an objective lens is irradiated onto an optical recording medium, and a beam of light reflected by the optical recording medium is divided into two beams of light. means, disposed at a position farther away from the optical recording medium than a convergence point of the beam of light reflected by the optical recording medium, and arranged in a direction corresponding to the track of the optical recording medium; A first light detecting section having three light detecting sections and receiving one of the two light beams divided by the dividing means.
a photodetector arranged at a position closer to the optical recording medium than a convergence point of the light beam reflected by the optical recording medium, and corresponding to a track of the optical recording medium; It has three photodetecting sections lined up in the direction, and is divided into two by the dividing means.
a second photodetector that receives the other of the two light beam bundles, and a photodetector on both sides of the first photodetector and the second photodetector the sum of the detection signals from each of the central photodetectors in the first photodetector and the detection signals from each of the center photodetectors in the first photodetector and the photodetectors on both sides of the second photodetector; A focus detection device that obtains a focus error signal of the optical recording medium by comparing the sum of .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7244084A JPS60217535A (en) | 1984-04-11 | 1984-04-11 | Focus detector |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7244084A JPS60217535A (en) | 1984-04-11 | 1984-04-11 | Focus detector |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS60217535A JPS60217535A (en) | 1985-10-31 |
| JPH0534732B2 true JPH0534732B2 (en) | 1993-05-24 |
Family
ID=13489349
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP7244084A Granted JPS60217535A (en) | 1984-04-11 | 1984-04-11 | Focus detector |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS60217535A (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1987005142A1 (en) * | 1986-02-24 | 1987-08-27 | Sony Corporation | Device for detecting focus |
| JP2701324B2 (en) * | 1988-06-16 | 1998-01-21 | ソニー株式会社 | Optical head device |
| JPH10116427A (en) * | 1996-10-09 | 1998-05-06 | Sony Corp | Servo signal processing device and optical disk device |
| US7138200B1 (en) | 1997-12-18 | 2006-11-21 | Toyota Jidosha Kabushiki Kaisha | Fuel cell and separator for the same |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS53112705A (en) * | 1977-03-14 | 1978-10-02 | Mitsubishi Electric Corp | Optical system information reproducer |
| JPS56152941U (en) * | 1980-04-14 | 1981-11-16 | ||
| JPS58211721A (en) * | 1982-06-04 | 1983-12-09 | Olympus Optical Co Ltd | Focusing detecting method |
| JPS6043234A (en) * | 1983-08-18 | 1985-03-07 | Mitsubishi Electric Corp | Detector for defocus of optical disk head |
| JPH07107742B2 (en) * | 1984-02-17 | 1995-11-15 | 三菱電機株式会社 | Optical disc head focus shift detector |
-
1984
- 1984-04-11 JP JP7244084A patent/JPS60217535A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS60217535A (en) | 1985-10-31 |
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