JPH0654554B2 - Magneto-optical reproducing device - Google Patents
Magneto-optical reproducing deviceInfo
- Publication number
- JPH0654554B2 JPH0654554B2 JP7327387A JP7327387A JPH0654554B2 JP H0654554 B2 JPH0654554 B2 JP H0654554B2 JP 7327387 A JP7327387 A JP 7327387A JP 7327387 A JP7327387 A JP 7327387A JP H0654554 B2 JPH0654554 B2 JP H0654554B2
- Authority
- JP
- Japan
- Prior art keywords
- magneto
- light
- signal
- output
- detection signal
- 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 - Fee Related
Links
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B19/00—Driving, starting, stopping record carriers not specifically of filamentary or web form, or of supports therefor; Control thereof; Control of operating function ; Driving both disc and head
- G11B19/02—Control of operating function, e.g. switching from recording to reproducing
- G11B19/04—Arrangements for preventing, inhibiting, or warning against double recording on the same blank or against other recording or reproducing malfunctions
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B11/00—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor
- G11B11/10—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field
- G11B11/105—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field using a beam of light or a magnetic field for recording by change of magnetisation and a beam of light for reproducing, i.e. magneto-optical, e.g. light-induced thermomagnetic recording, spin magnetisation recording, Kerr or Faraday effect reproducing
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B11/00—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor
- G11B11/10—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field
- G11B11/105—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field using a beam of light or a magnetic field for recording by change of magnetisation and a beam of light for reproducing, i.e. magneto-optical, e.g. light-induced thermomagnetic recording, spin magnetisation recording, Kerr or Faraday effect reproducing
- G11B11/10502—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field using a beam of light or a magnetic field for recording by change of magnetisation and a beam of light for reproducing, i.e. magneto-optical, e.g. light-induced thermomagnetic recording, spin magnetisation recording, Kerr or Faraday effect reproducing characterised by the transducing operation to be executed
- G11B11/10515—Reproducing
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B11/00—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor
- G11B11/10—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field
- G11B11/105—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field using a beam of light or a magnetic field for recording by change of magnetisation and a beam of light for reproducing, i.e. magneto-optical, e.g. light-induced thermomagnetic recording, spin magnetisation recording, Kerr or Faraday effect reproducing
- G11B11/10532—Heads
- G11B11/10541—Heads for reproducing
- G11B11/10543—Heads for reproducing using optical beam of radiation
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B11/00—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor
- G11B11/10—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field
- G11B11/105—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field using a beam of light or a magnetic field for recording by change of magnetisation and a beam of light for reproducing, i.e. magneto-optical, e.g. light-induced thermomagnetic recording, spin magnetisation recording, Kerr or Faraday effect reproducing
- G11B11/10595—Control of operating function
- G11B11/10597—Adaptations for transducing various formats on the same or different carriers
-
- 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
- G11B7/0948—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 specially adapted for detection and avoidance or compensation of imperfections on the carrier, e.g. dust, scratches, dropouts
Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、レーザ発振器と、レーザ発振器から発射さ
れ、光磁気記録媒体面上に照射された光束の反射光ある
いは透過光の光路中に配設された光分割手段と、光分割
手段によって分割された両光束の情報信号をそれぞれ検
出する第１，第２の光検出器と、第１および第２の光検
出器からの情報信号の差信号を検出する差動増幅器とを
有する光磁気再生装置に関する。The present invention relates to a laser oscillator and an optical path of reflected light or transmitted light of a light beam emitted from the laser oscillator and irradiated on the surface of a magneto-optical recording medium. Difference between the information signal from the first and second photodetectors, and the provided light splitting means, the first and second photodetectors that detect the information signals of both light beams split by the light splitting means, respectively. The present invention relates to a magneto-optical reproducing device having a differential amplifier that detects a signal.
従来、この種の光磁気再生装置は、情報信号の記録され
た光磁気記録媒体から磁気記録情報を再生するのにカー
効果、ファラデー効果と呼ばれる磁気光学効果を利用し
ている。Conventionally, this type of magneto-optical reproducing apparatus utilizes a magneto-optical effect called Kerr effect or Faraday effect to reproduce magnetic recording information from a magneto-optical recording medium on which an information signal is recorded.
第４図はカー効果を利用した従来の光磁気記録再生装置
を示す構成図である。この光磁気記録再生装置では、半
導体レーザ１より発射させるレーザ光はコリメータレン
ズ２により平行光に直され、偏光子３、ビームスプリッ
タ４を通り、対物レンズ５によって微小な光スポットに
絞られて、光磁気記録媒体６の表面に照射されて反射さ
れる。このとき、照射される光磁気記録媒体の磁化状態
によって反射光の変更状態が変化する。反射光は再び対
物レンズ５を通りビームスプリッタ４によって光路を曲
げられて1/2波長板７を通り、反射光の偏光面を回転さ
せて、検光子８に送られ、反射光の偏光面に応じてレン
ズ101 またはレンズ102 へ導かれそれぞれ光検出器11
1 ，112 に集光されて、対応する信号が出力される。検
出器111 ，112 の出力はそれぞれ差動増幅器の12の非反
転，反転入力端に入力され、差動増幅器12で増幅されＲ
Ｆ検出信号27として出力される。FIG. 4 is a block diagram showing a conventional magneto-optical recording / reproducing apparatus utilizing the Kerr effect. In this magneto-optical recording / reproducing apparatus, the laser light emitted from the semiconductor laser 1 is converted into parallel light by the collimator lens 2, passes through the polarizer 3 and the beam splitter 4, and is narrowed down to a minute light spot by the objective lens 5. The surface of the magneto-optical recording medium 6 is irradiated and reflected. At this time, the changed state of the reflected light changes depending on the magnetized state of the irradiated magneto-optical recording medium. The reflected light passes through the objective lens 5 again, the optical path is bent by the beam splitter 4, passes through the half-wave plate 7, rotates the polarization plane of the reflected light, and is sent to the analyzer 8, where it becomes the polarization plane of the reflected light. Depending on the condition, the light is guided to the lens 10 1 or the lens 10 2 , respectively, and the photodetector 11
1, 11 2 are focused on, the corresponding signal is output. The outputs of the detectors 11 1 and 11 2 are input to the non-inverting and inverting input terminals of the differential amplifier 12, amplified by the differential amplifier 12, and R
The F detection signal 27 is output.
第５図は磁気カー効果を利用した光磁気記録の再生原理
を説明するための図である。Ｐｉは光磁気記録媒体６に
入射する偏光を、Ｒ＋は例えば媒体膜面下方に磁化され
た領域から反射される偏光を、Ｒ−は媒体膜面上方に磁
化された領域から反射される偏光をそれぞれ表してい
る。また、θｋはカー回転角と呼ばれるもので磁化光学
効果によって光の振動面が回転する量を表わしている。
このとき、光磁気記録媒体６の交互に磁化された領域を
再生光スポットが走査するときに、1/2波長板７を消光
位置から設定角θだけ機械的に回転させると、その透過
光は機械媒体から反射される光量をＰとして、次式(1)
で表される強度差Ｓをもった変調光となり、光検出器11
1 ，112 によって光再生される。FIG. 5 is a diagram for explaining the reproducing principle of magneto-optical recording utilizing the magnetic Kerr effect. Pi is polarized light incident on the magneto-optical recording medium 6, R + is polarized light reflected from a region magnetized below the medium film surface, and R − is polarized light reflected from a region magnetized above the medium film surface. Respectively. Further, θ k is called a Kerr rotation angle and represents the amount of rotation of the vibrating surface of light due to the magnetization optical effect.
At this time, when the reproducing light spot scans the alternately magnetized areas of the magneto-optical recording medium 6, if the 1/2 wavelength plate 7 is mechanically rotated from the extinction position by the set angle θ, the transmitted light is Assuming that the amount of light reflected from the mechanical medium is P, the following equation (1)
The modulated light has an intensity difference S represented by
Light is regenerated by 1 , 11 2 .
Ｓ＝Ｐsin ２θk sin ２θ ……(1) この場合、再生信号の信号対雑音比（ＳＮ比）を最大に
するように1/2波長板７を機械的に回転させて設定角θ
を最適な設定角θ０に設定する必要がある。この1/2波
長板７の設定角θには、光検出器111 ，112 に係るノイ
ズと記録媒体６からの反射光の変動によるノイズが大き
く影響してくる。そこで、反射光の変動による同相ノイ
ズを除去する方法として、第４図で示されるような差動
検出法が広く用いられる。S = P sin 2θ k sin 2θ (1) In this case, the half-wave plate 7 is mechanically rotated to maximize the signal-to-noise ratio (SN ratio) of the reproduced signal, and the set angle θ
Should be set to an optimum setting angle θ 0 . The set angle θ of the half-wave plate 7 is greatly affected by the noise associated with the photodetectors 11 1 and 11 2 and the noise caused by the fluctuation of the reflected light from the recording medium 6. Therefore, the differential detection method as shown in FIG. 4 is widely used as a method for removing the in-phase noise due to the fluctuation of the reflected light.
上述した従来の光磁気記録再生装置は、光磁気記録媒体
の欠陥部分をＲＦ検出信号の振幅低下として検出してい
たので、欠陥部分の検出が不十分であり、特に映像信号
をＦＭ変調して記録再生するアナログ方式においては、
欠陥部分が視覚上の画室をとすノイズとして表われると
いう欠点がある。Since the conventional magneto-optical recording / reproducing apparatus described above detects a defective portion of the magneto-optical recording medium as a decrease in the amplitude of the RF detection signal, the defective portion is insufficiently detected. In particular, the video signal is FM-modulated. In the analog method of recording and reproducing,
There is a drawback in that the defective portion appears as noise in the visual room.
本発明の光磁気再生装置は、 第１，第２の光検出器からの情報信号の和信号を検出す
る加算像幅器と、 加算増幅器の出力を入力し、その入力が予め設定された
第１の基準比較振幅値を超えたことを検出すると検出信
号を出力する第１の振幅検出器と、作動増幅器の出力を
入力し、その入力が予め設定された第２の基準比較振幅
値を超えたことを検出すると検出信号を出力する第２の
振幅検出器と、 第１，第２の振幅検出器の検出信号の理論和をとり、欠
陥検出信号を出力する理論和回路とを有する。The magneto-optical reproducing apparatus of the present invention is configured such that a summing image width detector that detects a sum signal of information signals from the first and second photodetectors and an output of a summing amplifier are input, and the input is preset. A first amplitude detector that outputs a detection signal when detecting that the reference reference amplitude value of 1 is exceeded and the output of the differential amplifier are input, and the input exceeds a preset second reference comparison amplitude value. It has a second amplitude detector that outputs a detection signal when it is detected, and a theoretical sum circuit that takes the theoretical sum of the detection signals of the first and second amplitude detectors and outputs a defect detection signal.
本発明は、光磁気記録媒体の欠陥部分には、反射率の変
化を伴う欠陥と、カー回転の変化を伴う欠陥があること
に着目し、第１，第２の光検出器の出力の和信号，差信
号を作成し、予め設定した第１，第２の基準比較振幅値
と比較して、それぞれの欠陥を検出することにより、欠
陥部分の検出能力を大幅に向上させるようにしたもので
ある。The present invention focuses on the fact that the defective portion of the magneto-optical recording medium has a defect with a change in reflectance and a defect with a change in Kerr rotation, and the sum of the outputs of the first and second photodetectors. A signal and a difference signal are created and compared with preset first and second reference comparison amplitude values to detect respective defects, thereby significantly improving the defect portion detection capability. is there.
次に、本発明の実施例について図面を参照して説明す
る。Next, embodiments of the present invention will be described with reference to the drawings.
第１図は本発明の光磁気再生装置の一実施例を示す構成
図、第２図，第３図は第１図中の比較器19，24，30の入
出力の関係を示す波形図である。FIG. 1 is a block diagram showing an embodiment of the magneto-optical reproducing apparatus of the present invention, and FIGS. 2 and 3 are waveform charts showing the input / output relations of the comparators 19, 24, 30 in FIG. is there.
本実施例は、第４図で示された従来例の光検出器111 ，
112 の出力を加算増幅する加算増幅器18と、反転入力端
には電源電圧＋Ｖを抵抗器21と可変抵抗器20とで分圧し
た電圧が基準比較振幅値ＶC1として印加され、非反転入
力端には加算増幅器18の出力が印加されている比較器19
と、反転入力端には電源電圧＋Ｖを抵抗器22と可変抵抗
器23とで分圧した電圧が基準比較振幅値ＶC2として印加
され、非反転入力端には作動増幅器12のＲＦ検出信号27
が印加されている比較器24と、非反転入力端には電源電
圧−Ｖを抵抗器29と可変抵抗器28とで分圧した電圧が基
準比較振幅器ＶC3として印加され、反転入力端には作動
増幅器12のＲＦ検出信号27が印加されている比較器30
と、比較器19，24，30の出力の理論和をとり欠陥検出信
号26として出力するオア回路25とが第４図の従来例に付
加されて構成されている。In this embodiment, the conventional photodetector 11 1 , shown in FIG.
11 and summing amplifier 18 which adds amplifying the second output, the inverting input terminal is applied a power supply voltage + V as a resistor 21 and variable resistor 20 and at the divided voltage reference comparison amplitude value V C1, the non-inverting input Comparator 19 to which the output of summing amplifier 18 is applied
And a voltage obtained by dividing the power supply voltage + V by the resistor 22 and the variable resistor 23 is applied as the reference comparison amplitude value V C2 to the inverting input terminal, and the RF detection signal 27 of the operational amplifier 12 is applied to the non-inverting input terminal.
Is applied to the non-inverting input terminal of the comparator 24 to which the power supply voltage −V is divided by the resistor 29 and the variable resistor 28 as the reference comparison amplitude unit V C3, and is applied to the inverting input terminal. Is a comparator 30 to which the RF detection signal 27 of the operational amplifier 12 is applied.
And an OR circuit 25 which outputs a defect detection signal 26 by taking the theoretical sum of the outputs of the comparators 19, 24 and 30 and is added to the conventional example of FIG.
次に本実施例の動作について説明する。Next, the operation of this embodiment will be described.
光検出器111 ，112 で検出される信号成分は逆位相のた
め、通常では加算増幅器18の出力端には出力がほとんど
表われない。しかし発射率変化をともなう欠陥部分があ
ったときには、光検出器111 ，112 で検出される信号は
同位相のため、加算増幅器18で増幅され、出力端に出力
が現われる。この出力が基準比較振幅値ＶC1を超えると
比較器19の出力が現われる（第２図）。光検出器111 お
よび122 で検出された信号成分は逆位相のため、差動増
幅器12にて増幅されＲＦ検出信号27として出力されてい
る。位相変化を伴う欠陥部分があったときは、再生光を
信号光と同様成分のため差動増幅器12にて増幅され、出
力に現われる。この増幅された欠陥部分の信号が、比較
器24においては基準比較振幅器値ＶC2上の特、また比較
器30においては基準比較振幅値ＶC3以下の時にそれぞれ
の出力にハイレベルの信号が出力される（第３図）。オ
ア回路25は比較器19，24，30の出力の論理和をとり、欠
陥検出信号26として出力する。したがって、欠陥補正回
路（不図示）はこの欠陥検出信号26に基づいて、再生映
像の信号の欠陥ノイズを補正できる。Since the signal components detected by the photodetectors 11 1 and 11 2 have opposite phases, almost no output appears at the output end of the summing amplifier 18. However, when there is a defective portion with a change in the firing rate, the signals detected by the photodetectors 11 1 and 11 2 have the same phase, so they are amplified by the summing amplifier 18 and an output appears at the output end. When this output exceeds the reference comparison amplitude value V C1 , the output of the comparator 19 appears (FIG. 2). Since the signal components detected by the photodetectors 11 1 and 12 2 have opposite phases, they are amplified by the differential amplifier 12 and output as the RF detection signal 27. When there is a defective portion accompanied by a phase change, the reproduced light has the same component as the signal light and is amplified by the differential amplifier 12 to appear in the output. When the amplified signal of the defective portion has a characteristic above the reference comparison amplitude value V C2 in the comparator 24 and below the reference comparison amplitude value V C3 in the comparator 30, a high level signal is output to each output. It is output (Fig. 3). The OR circuit 25 takes the logical sum of the outputs of the comparators 19, 24 and 30 and outputs it as the defect detection signal 26. Therefore, the defect correction circuit (not shown) can correct the defect noise of the reproduced video signal based on the defect detection signal 26.
以上説明したように本発明は、光磁気記録媒体の欠陥部
分には、反射率の変化を伴う欠陥と、カー回転の変化を
伴う欠陥があることに着目し、第１，第２の光検出器の
出力の和信号、差信号を作成し、予め設定した第１，第
２の基準比較振幅値と比較して、それぞれの欠陥を検出
することにより、欠陥部分の検出能力を大幅に向上でき
る効果があり、その結果、映像信号をＦＭ変調して記録
再生するアナログ方式の光磁気記録再生装置等において
は、欠陥検出信号で欠陥補正回路を制御することによ
り、欠陥ノイズを十分に補正することが可能になり、画
面上に欠陥ノイズが目立たない高品位な記録再生画像を
得ることができる効果もある。As described above, the present invention focuses on the fact that the defective portion of the magneto-optical recording medium has a defect with a change in reflectance and a defect with a change in Kerr rotation. By detecting the respective defects by creating a sum signal and a difference signal of the output of the container and comparing them with the preset first and second reference comparison amplitude values, it is possible to significantly improve the defect detection capability. As a result, in an analog type magneto-optical recording / reproducing apparatus or the like that FM-modulates a video signal for recording / reproducing, defect noise is sufficiently corrected by controlling a defect correction circuit with a defect detection signal. It is also possible to obtain a high-quality recorded / reproduced image in which defect noise is not noticeable on the screen.
【図面の簡単な説明】 第１図は本発明の光磁気再生装置の一実施例を示す構成
図、第２図，第３図は比較器19，24，30の入出力の関係
を示す波形図、第４図は従来例を示す構成図、第５図は
磁気カー効果を利用した光磁気記録の再生原理を示す説
明図である。 １……半導体レーザ、 ２……コリメータレンズ、 ３……偏光子、 ４……ビームスプリッタ、 ５……対物レンズ、 ６……光磁気記録媒体、 ７……1/2波長板、 ８……検光子、 10１，10２……レンズ、 11１，11２……光検出器、 12……差動増幅器、 18……加算増幅器、 19，24，30……比較器、 20，23，28……可変抵抗器、 21，22，29……抵抗器、 25……オア回路、 26……欠陥検出信号、 27……ＲＦ検出信号。BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of a magneto-optical reproducing apparatus of the present invention, and FIGS. 2 and 3 are waveforms showing the input / output relationship of the comparators 19, 24, 30. FIG. 4 and FIG. 4 are configuration diagrams showing a conventional example, and FIG. 5 is an explanatory diagram showing the reproducing principle of magneto-optical recording utilizing the magnetic Kerr effect. 1 ... Semiconductor laser, 2 ... Collimator lens, 3 ... Polarizer, 4 ... Beam splitter, 5 ... Objective lens, 6 ... Magneto-optical recording medium, 7 ... 1/2 wavelength plate, 8 ... Analyzer, 10 1 , 10 2 ...... Lens, 11 1 , 11 2 ...... Photo detector, 12 ...... Differential amplifier, 18 …… Adding amplifier, 19,24,30 …… Comparator, 20,23, 28: Variable resistor, 21, 22, 29 ... Resistor, 25 ... OR circuit, 26 ... Defect detection signal, 27 ... RF detection signal.
Claims (1)
れ、光磁気記録媒体面上に照射された光束の反射光ある
いは透過光の光路中に配設された光分割手段と、光分割
手段によって分割された両光束の情報信号をそれぞれ検
出する第１，第２の光検出器と、第１および第２の光検
出器からの情報信号の差信号を検出する差動増幅器とを
有する光磁気再生装置において、 第１，第２の光検出器からの情報信号の和信号を検出す
る加算増幅器と、 加算増幅器の出力を入力し、その入力が予め設定された
第１の基準比較振幅値を超えたことを検出すると検出信
号を出力する第１の振幅検出器と、 差動増幅器の出力を入力し、その入力が予め設定された
第２の基準比較振幅値を超えたことを検出すると検出信
号を出力する第２の振幅検出器と、 第１，第２の振幅検出器の検出信号の論理和をとり、欠
陥検出信号を出力する論理和回路とを有することを特徴
とする光磁気再生装置。1. A laser oscillator, a light splitting means disposed in the optical path of reflected light or transmitted light of a light beam emitted from the laser oscillator and irradiated on the surface of the magneto-optical recording medium, and splitting by the light splitting means. Magneto-optical reproduction having first and second photo-detectors for respectively detecting the information signals of the two luminous fluxes, and a differential amplifier for detecting a difference signal of the information signals from the first and second photo-detectors In the device, a summing amplifier that detects the sum signal of the information signals from the first and second photodetectors, and the output of the summing amplifier are input, and the input exceeds a preset first reference comparison amplitude value. The first amplitude detector, which outputs a detection signal when it detects that it is detected, and the output of the differential amplifier are input, and the detection signal is detected when the input exceeds the preset second reference comparison amplitude value. A second amplitude detector for outputting , A logical sum circuit for taking a logical sum of the detection signals of the second amplitude detector and outputting a defect detection signal.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7327387A JPH0654554B2 (en) | 1987-03-26 | 1987-03-26 | Magneto-optical reproducing device |
| US07/149,565 US4951154A (en) | 1987-01-28 | 1988-01-28 | Magneto-optic recording/reproducing apparatus |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7327387A JPH0654554B2 (en) | 1987-03-26 | 1987-03-26 | Magneto-optical reproducing device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS63239639A JPS63239639A (en) | 1988-10-05 |
| JPH0654554B2 true JPH0654554B2 (en) | 1994-07-20 |
Family
ID=13513384
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP7327387A Expired - Fee Related JPH0654554B2 (en) | 1987-01-28 | 1987-03-26 | Magneto-optical reproducing device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0654554B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2944411B2 (en) * | 1994-03-22 | 1999-09-06 | 三洋電機株式会社 | Pit / groove discrimination circuit |
-
1987
- 1987-03-26 JP JP7327387A patent/JPH0654554B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPS63239639A (en) | 1988-10-05 |
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| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |