JPH02158943A - Optical head device - Google Patents
Optical head deviceInfo
- Publication number
- JPH02158943A JPH02158943A JP31351888A JP31351888A JPH02158943A JP H02158943 A JPH02158943 A JP H02158943A JP 31351888 A JP31351888 A JP 31351888A JP 31351888 A JP31351888 A JP 31351888A JP H02158943 A JPH02158943 A JP H02158943A
- Authority
- JP
- Japan
- Prior art keywords
- beam splitter
- optical
- reflected
- head device
- polarization direction
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 230000003287 optical effect Effects 0.000 title claims abstract description 49
- 230000010287 polarization Effects 0.000 claims abstract description 27
- 239000013078 crystal Substances 0.000 abstract description 23
- 230000001172 regenerating effect Effects 0.000 abstract 1
- 238000010586 diagram Methods 0.000 description 6
- 239000010453 quartz Substances 0.000 description 5
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 5
- 239000000853 adhesive Substances 0.000 description 3
- 230000001070 adhesive effect Effects 0.000 description 3
- 239000002131 composite material Substances 0.000 description 3
- 230000006866 deterioration Effects 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 239000004065 semiconductor Substances 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000015556 catabolic process Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- NJPPVKZQTLUDBO-UHFFFAOYSA-N novaluron Chemical compound C1=C(Cl)C(OC(F)(F)C(OC(F)(F)F)F)=CC=C1NC(=O)NC(=O)C1=C(F)C=CC=C1F NJPPVKZQTLUDBO-UHFFFAOYSA-N 0.000 description 1
Abstract
Description
【発明の詳細な説明】
〔概要〕
光磁気ディスク装置の光学ヘッド装置に関し、組立ての
簡略化を可能とすることを［」的とし、記録媒体で反射
したビームをＳ偏光成分とＰ偏光成分とに分けて夫々光
検出器に向かわせる偏光ビームスプリッタを備えてなる
光学ヘッド装置において、該偏光ビームスプリッタの入
射面側に、厚さが上記反射ビームが透過することにより
、該反射ビームの偏光方向を４５度回転させる寸法に定
められた旋光子を設けて構成する。[Detailed Description of the Invention] [Summary] The aim is to simplify the assembly of an optical head device for a magneto-optical disk device, and the beam reflected by a recording medium is divided into an S-polarized component and a P-polarized component. In an optical head device comprising a polarizing beam splitter that separates the beams into two beams and directs them to the photodetectors, the polarizing beam splitter has a thickness on the incident surface side that allows the reflected beam to pass therethrough, thereby changing the polarization direction of the reflected beam. It is constructed by providing an optical rotator sized to rotate the light by 45 degrees.
（産業上の利用分野〕
本発明は光磁気ディスク装置の光学ヘッド装置に関する
。(Industrial Application Field) The present invention relates to an optical head device for a magneto-optical disk device.
光磁気ディスク装置の光学ヘッド装置は、ディスクから
反射してくる光の僅かな偏光面の変化を読み取る構成で
あり、光磁気ディスクのうちの無記録部分からの反射ビ
ームの偏光り向がＰ（−光方向に対して４５度の方向と
なっていることが必要である。なお、この光学ヘッド装
置は組立てし易い構成であることが望ましい。The optical head device of a magneto-optical disk device is configured to read slight changes in the polarization plane of light reflected from the disk, and the polarization direction of the reflected beam from the non-recording portion of the magneto-optical disk is P( - It is necessary that the direction is 45 degrees with respect to the light direction.It is desirable that this optical head device has a configuration that is easy to assemble.
第６図は従来の光学ヘッド装置を示す。１は半導体レー
ザ、２は対物レンズ、３は偏光ビームスプリッタ、４．
５は光検出器である。６は１／２波長板であり、偏光方
向を上記のように設定するためのものである。FIG. 6 shows a conventional optical head device. 1 is a semiconductor laser, 2 is an objective lens, 3 is a polarizing beam splitter, 4.
5 is a photodetector. 6 is a 1/2 wavelength plate, which is used to set the polarization direction as described above.
半導体レーザ１より出射したＰ方向の直線偏光は、コリ
メートレンズ７、真円補正プリズム８゜ビームスプリッ
タ９１反射ミラー１０．対物レンズ２を通って、光磁気
ディスク１１上に集光される。光磁気ディスク１１から
の反射ビームは、ちと来た経路を戻り、今度はビームス
プリッタ９で反射され、偏光ビームスプリッタ３に入射
する前に、第７図に併せて示すように１／２波長板６を
通過する。The linearly polarized light in the P direction emitted from the semiconductor laser 1 is passed through a collimating lens 7 , a circular correction prism 8 , a beam splitter 91 , a reflecting mirror 10 . The light passes through the objective lens 2 and is focused onto the magneto-optical disk 11 . The reflected beam from the magneto-optical disk 11 returns along the path it came from, is reflected by the beam splitter 9, and is passed through a 1/2 wavelength plate before entering the polarizing beam splitter 3, as also shown in FIG. Pass 6.
この１／２波長板６は、結晶軸６ａがＰ（Ｑ光方向に対
して２２．５度をなす向きに定めである。反射ビーム１
２は、この１／２波艮根６を通過することにより、第７
図に示すように、偏光方向をＰ偏光方向に対して４５度
方向とされる。The crystal axis 6a of this half-wave plate 6 is oriented at 22.5 degrees with respect to the P (Q light direction).The reflected beam 1
2 passes through this 1/2 wave root 6, and the seventh
As shown in the figure, the polarization direction is set at 45 degrees with respect to the P polarization direction.
この反射ビーム１２Ａが偏光ビームスプリッタ３により
Ｐ成分の光１２ＡｐとＳ成分の光１２Ａｓとに分けられ
、それぞれレンズ３９．４０を通って光検出器４．５に
到る。This reflected beam 12A is split by the polarizing beam splitter 3 into P component light 12Ap and S component light 12As, which each pass through lenses 39 and 40 and reach a photodetector 4.5.
差動増幅器１３により各光検出器４．５の差動出力を取
り、端子１４より再生信号が得られる。A differential amplifier 13 takes the differential output of each photodetector 4.5, and a reproduced signal is obtained from a terminal 14.
また一方の光検出器４により焦点誤差信号とトラッキン
グ誤差信号とが検出され、端子１５より出力される。こ
の誤差信号に基づいて対物レンズ２が駆動され焦点制御
及びドラッギング制御がなされる。Further, a focus error signal and a tracking error signal are detected by one photodetector 4 and outputted from a terminal 15. The objective lens 2 is driven based on this error signal, and focus control and dragging control are performed.
ここで反射ビーム１２Ａの偏光方向がＰ偏光方向に対し
て正確に４５度方向となっていることが手要である。第
８図中、線１６で示すように、反射ビーム１２Ａの偏光
方向がＰ偏光方向に対して４５度方向よりずれると、再
生信号の劣化量が増えるからである。Here, it is important that the polarization direction of the reflected beam 12A is exactly 45 degrees with respect to the P polarization direction. This is because, as shown by line 16 in FIG. 8, if the polarization direction of the reflected beam 12A deviates from 45 degrees with respect to the P polarization direction, the amount of deterioration of the reproduced signal increases.
信号劣化の許容間を１ｄＢ程度とすると、反射ビーム１
２Ａの偏光方向の許容ずれ角度は±１度であり、１／２
波長板６の設定角度のずれ許容度は±０．５度と僅かで
ある。また１／２波長板を母材から切り出す段階で、結
晶軸の外形形状に対する誤差が生じ易い。Assuming that the signal degradation tolerance is approximately 1 dB, the reflected beam 1
The allowable deviation angle of the polarization direction of 2A is ±1 degree, which is 1/2
The deviation tolerance of the set angle of the wave plate 6 is as small as ±0.5 degrees. Further, at the stage of cutting out the half-wave plate from the base material, errors in the external shape of the crystal axis are likely to occur.
このため、１／２波長板６をその結晶軸方向の角度を精
度良く定めて偏光ビームスプリッタ３の側面に接着固定
することは、実際上困難である。For this reason, it is actually difficult to adhesively fix the half-wave plate 6 to the side surface of the polarizing beam splitter 3 while accurately determining the angle of the crystal axis direction of the half-wave plate 6.
そこで、実際には、調整機構を設け、１／２波長板６は
その結晶軸６ａの方向が調整可能なように組み込まれて
いた。Therefore, in practice, an adjustment mechanism was provided, and the half-wave plate 6 was incorporated so that the direction of its crystal axis 6a could be adjusted.
即ち、第９図に示すように、１／２波長板６は一旦リン
グ状のホルダ１７に固定され、このホルダ１７を、ビー
ムスプリッタ９と偏光ビームスプリッタ３との間に設け
たＶ字状の台座１８に搭載し１、板ばね部材１９により
押さえ、調整ロンド２０によりホルダ１７を適宜回動さ
せ調整し、その位置に接着して固定されている。That is, as shown in FIG. 9, the half-wave plate 6 is temporarily fixed to a ring-shaped holder 17, and this holder 17 is attached to a V-shaped plate provided between the beam splitter 9 and the polarizing beam splitter 3. The holder 17 is mounted on a pedestal 18, held down by a leaf spring member 19, adjusted by appropriately rotating the holder 17 with an adjustment iron 20, and fixed in place by adhesive.
このため、光学ヘッド装置の組立工程が多くなり、また
部品点数も多くなり、これにより、製造コストが高くな
り、信頼性も十分でないという問題点があった。For this reason, the number of assembly steps for the optical head device increases, and the number of parts also increases, resulting in higher manufacturing costs and insufficient reliability.
本発明は組立の簡略化を可能とする光学ヘッドを提供す
ることを目的とする。SUMMARY OF THE INVENTION An object of the present invention is to provide an optical head whose assembly can be simplified.
本発明は、記録媒体で反射したビームをＳ偏光成分とＰ
偏光成分とに分けて夫々光検出器に向かわせる偏光ビー
ムスプリッタを備えてなる光学ヘッド装置において、
該偏光ビームスプリッタの入射面側に、厚さが上記反射
ビームが透過することにより、該反射ビームの偏光り向
を４５度回転させる寸法に定められた旋光子を設けてな
る構成としたものである。The present invention converts the beam reflected by the recording medium into an S-polarized component and a P-polarized component.
In an optical head device comprising a polarizing beam splitter that separates polarized light components and directs them to a photodetector, the reflected beam has a thickness such that the reflected beam is transmitted through the incident surface side of the polarized beam splitter. The structure includes an optical rotator whose dimension is determined to rotate the polarization direction of the light by 45 degrees.
旋光子の偏光ビームスプリッタに対する取付は位置の調
整は不要であり、組立性が良い。The attachment of the optical rotator to the polarizing beam splitter requires no position adjustment, and is easy to assemble.
第１図は本発明の一実施例の光学ヘッド装置３０を示す
。図中、第６図に示す構成部分と実質上対応する部分に
は同一符号を付し、その説明は省略する。FIG. 1 shows an optical head device 30 according to an embodiment of the present invention. In the figure, the same reference numerals are given to the parts that substantially correspond to the constituent parts shown in FIG. 6, and the explanation thereof will be omitted.
ビームスプリッタ９Ａと真円補正プリズム８Ａとは接着
固定してあり、偏光ビームスプリッタ３Ａとプリズム３
１とが接着固定してあり、共にベース３２上に固定しで
ある。The beam splitter 9A and the circular correction prism 8A are fixed with adhesive, and the polarizing beam splitter 3A and the prism 3
1 are fixed with adhesive, and both are fixed on the base 32.
３３は旋光子としての水晶板であり、ビームスプリッタ
９Ａと偏光ビームスプリッタ３△とに接着固定されて、
両者間に挾んで設けである。33 is a crystal plate as an optical rotator, which is adhesively fixed to the beam splitter 9A and the polarizing beam splitter 3Δ;
It is placed between the two.
水晶板３３は、第４図に示すように、水晶の母材よりそ
の結晶軸３４に垂直に所定の１７ざしに切り出したもの
である。As shown in FIG. 4, the crystal plate 33 is cut out from a crystal base material in 17 predetermined directions perpendicular to its crystal axis 34.
このように切り出した水晶板３３は、複屈折性が無くな
り、代わりに旋光性が表われる。第３図に示すように、
この水晶板３３に、偏光方向が符号３５で示す方向であ
る直線偏光を入射させると、偏光方向が例えば矢印３６
方向に回動し、射出したビームの偏光方向は符号３７で
示す方向となる。The crystal plate 33 cut out in this manner loses birefringence and exhibits optical rotation instead. As shown in Figure 3,
When linearly polarized light whose polarization direction is the direction indicated by reference numeral 35 is incident on this crystal plate 33, the polarization direction is, for example, indicated by the arrow 36.
The polarization direction of the emitted beam becomes the direction indicated by reference numeral 37.
旋光性（単位厚さあたりの偏光方向の回転角度）は光の
波長に依存し、水晶におけるこの関係は、第５図中線工
で示す如くである。半導体レーザ１よりのレーザの波長
である３８０ｎｍでは、旋光性は１０．７度／ｍである
。Optical rotation (rotation angle of polarization direction per unit thickness) depends on the wavelength of light, and this relationship in quartz crystal is as shown by the line in FIG. 5. At 380 nm, which is the wavelength of the laser from the semiconductor laser 1, the optical rotation is 10.7 degrees/m.
本実施例では、偏光方向を４５度回転させることを予定
しており、水晶板３３の厚さｔは４５／１０．７＝ ４
．２．としである。In this embodiment, the polarization direction is planned to be rotated by 45 degrees, and the thickness t of the crystal plate 33 is 45/10.7=4.
．． 2. It's Toshide.
上記の水晶板３３では、厚さｔだけで偏光方向の回転角
が決まり、偏光ビームスプリッタ３Ａに対する位置精度
等は偏光方向の回転角には全く関係が無くなる。In the above crystal plate 33, the rotation angle of the polarization direction is determined only by the thickness t, and the positional accuracy with respect to the polarization beam splitter 3A has no relation to the rotation angle of the polarization direction.
従って、上記の光学ヘッド装置３０において、水晶板３
３に関する調整機構は不要であり、水晶板３３はビーム
スプリッタ９Ａと偏光ビームスプリッタ３Ａとの間に固
定してあればよい。Therefore, in the optical head device 30 described above, the crystal plate 3
3 is not necessary, and the crystal plate 33 only needs to be fixed between the beam splitter 9A and the polarizing beam splitter 3A.
上記の光学ヘッド装置３０において、水晶板３３は、一
方の面をビームスプリッタ９Ａ、反対側の面を偏光ビー
ムスプリッタ３Ａに接着固定されて、ビームスプリッタ
９Ａ及び偏光ビームスプリッタ３Ａと一体化されて、符
号３８で示すように複合光学素子化されており、部品点
数の削減が図られている。また、複合光学素子３８を組
立てる場合にも、水晶板３３についてはその取ｆ−Ｊけ
方向についての粘度は気にする必要がなく、組立ては簡
単である。In the above-mentioned optical head device 30, the crystal plate 33 is adhesively fixed to the beam splitter 9A on one side and the polarizing beam splitter 3A on the opposite side, and is integrated with the beam splitter 9A and the polarizing beam splitter 3A. As shown by reference numeral 38, it is made into a composite optical element, and the number of parts is reduced. Furthermore, when assembling the composite optical element 38, there is no need to worry about the viscosity of the crystal plate 33 in the f-J direction, and assembly is simple.
上記の光学ヘッド装置３０は、ベース３２上に複合光学
素子３８を組み飼ければ足り、組み立ては、従来に比べ
て簡単である。The above-described optical head device 30 can be assembled simply by assembling the composite optical element 38 on the base 32, and is easier to assemble than in the past.
次に上記の光学ヘッド装置３０の動作について、第１図
及び第２図を参照して説明する。Next, the operation of the optical head device 30 described above will be explained with reference to FIGS. 1 and 2.
光磁気ディスク１１よりの反射ビーム１２であるＰｌａ
光のビームはビームス１リツタ９Ａで反射され、偏光ビ
ームスプリッタ３Ａ方向に向かう。Pla, which is the reflected beam 12 from the magneto-optical disk 11;
The light beam is reflected by the beam splitter 9A and heads toward the polarizing beam splitter 3A.
この反射ビーム１２は水晶板３３を透過し、ここで４５
度旋光され、第２図に示すように偏光方向３９がＰ偏光
方向に対して４５度をなすビーム１２Ａとされ、偏光ビ
ームスプリッタ３Ａに入り、ここで萌記と同様に分岐さ
れ、夫々レンズ３９゜４０を通って光検出器４，５に到
る。端子１４より再生信号が出力され、端子１５よりフ
ォーカス誤差信号、トラッキング誤差信号が出力される
。This reflected beam 12 is transmitted through a crystal plate 33, where 45
As shown in FIG. 2, the beam 12A is turned into a beam 12A whose polarization direction 39 is at an angle of 45 degrees with respect to the P polarization direction, and enters the polarization beam splitter 3A, where it is split in the same manner as in Moeki, and is split into a beam 12A with a polarization direction 39 at an angle of 45 degrees with respect to the P polarization direction, as shown in FIG. 40 and reach the photodetectors 4 and 5. A reproduction signal is output from the terminal 14, and a focus error signal and a tracking error signal are output from the terminal 15.
また、上記の水晶板３３の代わりに、他の旋光性を有す
る材質製の板を用いてもよい。Further, instead of the above-mentioned quartz plate 33, a plate made of another material having optical rotation may be used.
以上説明した様に、本発明によれば、旋光−ｆの取付は
角度の調整が全く不要であり、旋光子が甲に組み付けて
あればよいため、光学ヘッドｖ装置の組立ての簡略化を
図ることが出来る。また旋光子の偏光ビームスプリッタ
に対する角度の調整が不要であるため、旋光子を偏光ビ
ームスプリッタの入射面に接着固定して光学部品を複合
化することも容易に出来る。部品点数を削減出来、光学
ヘッド装置の信頼性の向上を図ることが出来る。As explained above, according to the present invention, there is no need to adjust the angle at all when attaching the optical rotation -f, and the optical rotation only needs to be assembled to the instep, which simplifies the assembly of the optical head v device. I can do it. Further, since it is not necessary to adjust the angle of the optical rotator with respect to the polarizing beam splitter, it is possible to easily combine the optical components by adhesively fixing the optical rotator to the incident surface of the polarizing beam splitter. The number of parts can be reduced and the reliability of the optical head device can be improved.
第１図は本発明の光学ヘッド装置の一実施例を示す図、
第２図は第１図の光学ヘッド装置の一部の概略図、
第３図は旋光子による旋光を説明する図、第４図は旋光
性を右する水晶板を示す図、第５図は水晶板の旋光性の
波長依存性を示ず図、第６図は従来の光学ヘッド装置を
示す図、第７図は第６図の光学ヘッド装置の一部の概略
図、
第８図は１／２波長板の結晶軸角度と再生信号劣化量の
関係を示す図、
第９図は１／２波長板のホルダへの取付けを示す図であ
る。
図において、
３Ａは偏光ビームスプリッタ、
９Ａはビームスプリッタ、
１１は光磁気ディスク、
１２．１２Ａは反射ビーム、
３０は光学ヘッド装置、
３２はベース、
３３は水晶板、
９４は結晶軸、
３８は複合光学素子
を示す。
特許出願人 富 士 通 株式会社
峯１図Ｃた零ヘード華５！の一部／）梼乞喫にづ第２図
水晶軟、１＝社る旋れ朗すつ図
オ匈プｔダ虹を岸ｉｆる吋（ｔし管之五１で１−５５第
４ 図
埼（ｈ七（のガ七尤オ’ｋｎ坏（ゐオに有斗を眉う刊丁
図夜来の吹２寮へ・シＬ′六（号Ｅ示す図第Ｃ図
ｑ略：乙すと３４へ５．Ｈ４＋舎ミ←セＢニゲ）−一−
１Ｐｉグフ１）羽ヒＪ６ξミコヌ２１第７図1 is a diagram showing an embodiment of the optical head device of the present invention, FIG. 2 is a schematic diagram of a part of the optical head device of FIG. 1, FIG. 3 is a diagram illustrating optical rotation by an optical rotator, Figure 4 shows a quartz plate that controls the optical rotation, Figure 5 shows the wavelength dependence of the optical rotation of the quartz plate, Figure 6 shows a conventional optical head device, and Figure 7 shows the wavelength dependence of the optical rotation of the quartz plate. Fig. 6 is a schematic diagram of a part of the optical head device, Fig. 8 is a diagram showing the relationship between the crystal axis angle of the 1/2 wavelength plate and the amount of deterioration of the reproduced signal, and Fig. 9 is a diagram showing the relationship between the crystal axis angle of the 1/2 wavelength plate and the amount of deterioration of the reproduced signal. It is a figure showing attachment. In the figure, 3A is a polarizing beam splitter, 9A is a beam splitter, 11 is a magneto-optical disk, 12. 12A is a reflected beam, 30 is an optical head device, 32 is a base, 33 is a crystal plate, 94 is a crystal axis, and 38 is a compound An optical element is shown. Patent Applicant: Fuji Tsu Co., Ltd. Part of /) Figure 2 of the song 1-55 No. 4 of the 1-55 Zusai(h7(h7(h7(h7)'s 7th Yūo'kn 坏(Io) to the 2nd dormitory of the night sky. To 34 5.H4+shami←SeBnige)-1-
1Pi Gouf 1) Hahi J6ξ Mikonu 21 Fig. 7
Claims (1)
に分けて夫々光検出器に向かわせる偏光ビームスプリッ
タを備えてなる光学ヘッド装置において、 該偏光ビームスプリッタ（３Ａ）の入射面側に、厚さ（
ｔ）が上記反射ビームが透過することにより、該反射ビ
ームの偏光方向を４５度回転させる寸法に定められた旋
光子（３３）を設けてなる構成の光学ヘッド装置。[Scope of Claims] An optical head device comprising a polarizing beam splitter that divides a beam reflected by a recording medium into an S-polarized component and a P-polarized component and directs the beam to a photodetector, comprising: the polarizing beam splitter (3A); The thickness (
t) is provided with an optical rotator (33) having a dimension that rotates the polarization direction of the reflected beam by 45 degrees when the reflected beam passes therethrough.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63313518A JP2965077B2 (en) | 1988-12-12 | 1988-12-12 | Optical head device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63313518A JP2965077B2 (en) | 1988-12-12 | 1988-12-12 | Optical head device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH02158943A true JPH02158943A (en) | 1990-06-19 |
| JP2965077B2 JP2965077B2 (en) | 1999-10-18 |
Family
ID=18042274
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63313518A Expired - Lifetime JP2965077B2 (en) | 1988-12-12 | 1988-12-12 | Optical head device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2965077B2 (en) |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS59203259A (en) * | 1983-05-04 | 1984-11-17 | Sanyo Electric Co Ltd | Optical magnetic disc device |
| JPS61199252A (en) * | 1985-02-28 | 1986-09-03 | Mitsubishi Electric Corp | Photomagnetic recording and reproducing device |
-
1988
- 1988-12-12 JP JP63313518A patent/JP2965077B2/en not_active Expired - Lifetime
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS59203259A (en) * | 1983-05-04 | 1984-11-17 | Sanyo Electric Co Ltd | Optical magnetic disc device |
| JPS61199252A (en) * | 1985-02-28 | 1986-09-03 | Mitsubishi Electric Corp | Photomagnetic recording and reproducing device |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2965077B2 (en) | 1999-10-18 |
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