JPS63177318A - Secondary distortion detector for optical recording information - Google Patents

Secondary distortion detector for optical recording information

Info

Publication number
JPS63177318A
JPS63177318A JP62007734A JP773487A JPS63177318A JP S63177318 A JPS63177318 A JP S63177318A JP 62007734 A JP62007734 A JP 62007734A JP 773487 A JP773487 A JP 773487A JP S63177318 A JPS63177318 A JP S63177318A
Authority
JP
Japan
Prior art keywords
signal
duty ratio
amplitude
information
recording
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
Application number
JP62007734A
Other languages
Japanese (ja)
Other versions
JP2600659B2 (en
Inventor
Kiyoshi Kimoto
木本　輝代志
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nikon Corp
Original Assignee
Nikon Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Nikon Corp filed Critical Nikon Corp
Priority to JP62007734A priority Critical patent/JP2600659B2/en
Publication of JPS63177318A publication Critical patent/JPS63177318A/en
Priority to US07/379,224 priority patent/US4979162A/en
Application granted granted Critical
Publication of JP2600659B2 publication Critical patent/JP2600659B2/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
    • G11B7/125—Optical beam sources therefor, e.g. laser control circuitry specially adapted for optical storage devices; Modulators, e.g. means for controlling the size or intensity of optical spots or optical traces
    • G11B7/126—Circuits, methods or arrangements for laser control or stabilisation
    • 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
    • G11B7/004—Recording, reproducing or erasing methods; Read, write or erase circuits therefor
    • G11B7/0045—Recording
    • 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
    • G11B7/007—Arrangement of the information on the record carrier, e.g. form of tracks, actual track shape, e.g. wobbled, or cross-section, e.g. v-shaped; Sequential information structures, e.g. sectoring or header formats within a track
    • 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
    • G11B7/007—Arrangement of the information on the record carrier, e.g. form of tracks, actual track shape, e.g. wobbled, or cross-section, e.g. v-shaped; Sequential information structures, e.g. sectoring or header formats within a track
    • G11B7/013—Arrangement of the information on the record carrier, e.g. form of tracks, actual track shape, e.g. wobbled, or cross-section, e.g. v-shaped; Sequential information structures, e.g. sectoring or header formats within a track for discrete information, i.e. where each information unit is stored in a distinct discrete location, e.g. digital information formats within a data block or sector

Landscapes

  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Measuring Magnetic Variables (AREA)
  • Optical Recording Or Reproduction (AREA)
  • Optical Head (AREA)

Abstract

PURPOSE:To detect the secondary distortion of information by providing the titled device with a reading means for reading out information from a medium for alternately recording binary information with the frequency of 50% proposed duty ratio. CONSTITUTION:Signals with bit length 2T and T are alternately recorded in an optical disk 1a. When these signals are reproduced by a head 1, the reproduced signal with the bit length 2T is not almost influenced by the fluctuation of the duty ratio, but the amplitude of the reproduced signal with the bit length is changed at the vertical position of a center level 12, i.e. the upper amplitude is reduced when the rate is <=50%, and increased when the ratio is >=50%. The upper and lower signals are envelope-detected 3a, 3b, respectively extracted through BPFs 4a, 4b (center frequency fc=1/tau) and converted into sine signals and amplitude peak values h1, h2 are detected. A decision logic 6 detects the presence or absence of secondary distortion and deviation from the 50% duty ratio based on the size relation of the peak values h1, h2. When h1=h2, the duty ratio of the reproduced signal are 50% and no generation of secondary distortion can be decided.

Description

【発明の詳細な説明】 （産業上の利用分野〉 本発明は、光ディスクや光磁気ディスク等の記録媒体に
記録された情報に含まれる二次歪の有無を検出する光学
式記録情報の二次歪検出装置に関する。DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention is a method for detecting the presence or absence of second-order distortion in information recorded on a recording medium such as an optical disk or a magneto-optical disk. This invention relates to a distortion detection device.

（従来技術） 従来、記録情報に基づくレーザービームの照射等で光デ
ィスクに機械的な凹凸形状でなる記録ピットの形で情報
を記録する場合、或いは光トゑ気ディスクに上下方向に
向いた磁化方向による記録ビットの形で情報を記録する
場合、適正なレーザーの駆動パワーを１ｑるためにデユ
ーティ比が５０％の２値信号を記録せしめ、媒体に記録
された記録情報のデユーティ比が５０％となるように即
ち二次歪を含まないようにレーザーパワーを校正し、校
正したレーザーパワーにより記録している。(Prior art) Conventionally, when information is recorded on an optical disk in the form of recording pits with a mechanical uneven shape by irradiation of a laser beam based on recorded information, or when an optical disk is used to record information in the form of recording pits with a mechanical unevenness, When recording information in the form of recording bits, a binary signal with a duty ratio of 50% is recorded in order to obtain an appropriate laser drive power of 1q, and the duty ratio of the recorded information recorded on the medium is 50%. The laser power is calibrated so that it does not contain second-order distortion, and recording is performed using the calibrated laser power.

ところで、光ディスクに記録された情報に含まれる二次
歪の測定には、通常、スペクトルアナラ−゛イザーが用
いられる。即ち、光ディスクの記録情報を読取ヘッドに
より光学的に読取って電気信号に変換し、読取ヘッドか
ら得られた情報再生信号をスペクトルアナイザーで解析
するようになる。Incidentally, a spectrum analyzer is usually used to measure second-order distortion contained in information recorded on an optical disc. That is, the information recorded on the optical disk is optically read by a reading head and converted into an electrical signal, and the information reproduction signal obtained from the reading head is analyzed by a spectrum analyzer.

このスペクトラムアナライザーにより記録情報の回折を
行なった場合、第８図（ａ　＞に示す（Ｔａ／Ｔ）で与
えられるデユーティ比が５０％となる理想的な記録信号
による記録状態にあっては、記録情報のスペクトルアナ
ライザーによる測定結果は第９図＜ａ　）に示すように
、記録周波数（基本周波数）ｆｓに対し３ｔ’ｓ、　５
ｆｓ、　　・・・というように奇数次のみのスペクトル
成分が得られる。When diffraction of recorded information is performed using this spectrum analyzer, in a recording state with an ideal recording signal in which the duty ratio given by (Ta/T) shown in Fig. 8 (a) is 50%, the recording The measurement results by the information spectrum analyzer are as shown in Figure 9 <a), with respect to the recording frequency (fundamental frequency) fs, 3t's, 5
Only odd-order spectral components such as fs, . . . are obtained.

一方、第８図（ｂ　）に示すように、記録信号のデユー
ティ比が５０％より小さかったり、逆に第２図＜Ｃ＞に
示すようにデユーティ比が５０％より大きかった場合に
は、このような記録信号による記録情報は第９図（ｂ　
）に示すスペクトルアナライザーの測定結果が得られ、
この場合には、記録周波数ｆｓに対し２ｆｓ、　３ｆｓ
、　４ｆｓ・・・というように偶数次のスペクトル成分
も生じ、この２ｆｓとなる二次のスペクトル成分を二次
歪という。On the other hand, if the duty ratio of the recording signal is smaller than 50% as shown in Fig. 8(b), or conversely if the duty ratio is larger than 50% as shown in Fig. 2 <C>, Recorded information by such a recording signal is shown in Fig. 9 (b
) The measurement results of the spectrum analyzer shown in
In this case, the recording frequency fs is 2fs, 3fs
Even-order spectral components such as , 4fs, etc. also occur, and this second-order spectral component of 2fs is called second-order distortion.

（発明が解決しようとする問題点） しかしながら、スペクトラムアナライザーを用いた従来
の二次歪検出方法にあっては、例えば二次歪が出ないよ
うに、即ち記録情報のデユーティ比を５０％に保つよう
に記録信号となるレーザーパワーを自動的にコントロー
ルすることが次の理由により困雌であった。(Problem to be solved by the invention) However, in the conventional second-order distortion detection method using a spectrum analyzer, for example, the duty ratio of recorded information is kept at 50% so that second-order distortion does not occur. It has been difficult to automatically control the laser power that serves as the recording signal for the following reasons.

第１に、スペクトラムアナライザーの測定結果にあって
は、第８図（ｂ　）　　（ｃ　）に示したように、記録
信号のデユーティ比が５０％より小さくとも逆に大きく
とも第９図（ｂ　”）に示したように二次歪を現わす二
次のスペクトラム成分が現われ、極性を検出できない。First, in the measurement results of the spectrum analyzer, as shown in FIGS. 8(b) and (c), whether the duty ratio of the recording signal is smaller than 50% or larger than 50%, the duty ratio shown in FIG. ), a second-order spectrum component representing second-order distortion appears, and the polarity cannot be detected.

従って、二次歪を検出できても二次歪を生じないデユー
ティ比５０％に対し記録信号のデユーティ比がどちらに
ずれているかが分らず、レーザーパワーの増減について
の判断ができなかった。Therefore, even if second-order distortion can be detected, it is not possible to determine which direction the duty ratio of the recording signal deviates from the 50% duty ratio at which no second-order distortion occurs, and it is not possible to determine whether the laser power should be increased or decreased.

第２に、記録周波数が低い場合、即ち、記録ビットが大
きくなった場合、スペクトラムアナライザーによる二次
スペクトル成分の検出精度が落ちるという問題があるこ
とから、記録周波数ｆｓを高くする必要があった。Second, when the recording frequency is low, that is, when the recording bits become large, there is a problem that the detection accuracy of the secondary spectrum component by the spectrum analyzer decreases, so it is necessary to increase the recording frequency fs.

しかし、記録周波数がある程度高くなると、読取光学系
のＭＴＦ周波数特性により二次スペクトル成分が検出で
きなくなる。即ち、ＭＴＦとは光学系が記録情報を検出
する感度の周波数特性を示したもので、第１０図に示す
特性となる。この第１０図から明らかなように、記録周
波数ｆｓを図示のようにある程度高くすると、二次スペ
クトル成分を与える２ｆｓにおいてはＭＴＦが零となり
、２ｆｓの信号を検出することができない。However, when the recording frequency becomes high to a certain extent, secondary spectral components cannot be detected due to the MTF frequency characteristics of the reading optical system. That is, the MTF indicates the frequency characteristic of the sensitivity with which the optical system detects recorded information, and is the characteristic shown in FIG. As is clear from FIG. 10, when the recording frequency fs is increased to a certain extent as shown, the MTF becomes zero at 2fs, which provides a secondary spectral component, and the 2fs signal cannot be detected.

〈問題点を解決するための手段〉 本発明は、このような従来の問題点に鑑みてなされたも
ので、光ディスク等の記録媒体の記録情報に含まれる２
次歪の有無を検出すると同時に極性即ち二次歪の原因と
なった記録信号のデユーティ比がデユーティ比５０％に
対しどちらの方向にずれているかも簡単に検出できるよ
うにした光学的記録情報の二次歪検出装置を提供するこ
とを目的とする。<Means for Solving the Problems> The present invention has been made in view of such conventional problems.
Optical recording information that makes it possible to detect the presence or absence of second-order distortion and at the same time easily detect the polarity, that is, the direction in which the duty ratio of the recording signal that caused the second-order distortion deviates from the duty ratio of 50%. An object of the present invention is to provide a second-order distortion detection device.

この目的を達成するため本発明にあっては、デユーティ
比５０％を予定した情報ビットを２つの異なる周波数に
よって交互に記録した記録媒体の記録部位からの光学的
な情報再生信号を対象とし、この情報再生信号を交流増
幅した後に振幅中心レベルの上側と下側で個別に包絡線
検波し、この各包Ｉ８線検波出力を帯域フィルタに通し
て振幅成分を抽出した後にそれぞれ振幅ピーク値を検出
し、検出ピーク値が等しいときにデユーティ比５０％で
二次歪なしと判断し、両者が異なっているとぎには二次
歪ありと判断する。In order to achieve this object, the present invention targets an optical information reproduction signal from a recording part of a recording medium in which information bits with a scheduled duty ratio of 50% are recorded alternately at two different frequencies. After alternating current amplification of the information reproduction signal, envelope detection is performed separately above and below the amplitude center level, and each envelope I8-line detection output is passed through a bandpass filter to extract the amplitude component, and then the amplitude peak value is detected for each. When the detected peak values are equal, it is determined that there is no secondary distortion at a duty ratio of 50%, and when the two are different, it is determined that there is secondary distortion.

更に二次歪ありと判断したときには、上側包絡線検波出
力に基づく第１の検出ピーク値が下側包絡線検波出力に
基づく第２の検出ピーク値より大きいときには、記録信
号のデユーティ比が５０％より小さいと判断し、一方、
逆の場合には記録信号のデユーティ比は５０％より大ぎ
いと判断するようにしたものである。Further, when it is determined that there is secondary distortion, and the first detected peak value based on the upper envelope detection output is larger than the second detection peak value based on the lower envelope detection output, the duty ratio of the recording signal is set to 50%. On the other hand,
In the opposite case, the duty ratio of the recording signal is determined to be greater than 50%.

（作用） このような本発明の構成によれば、周波数の低い情報再
生信号と周波数の高い情報再生信号が記録情報の光学的
な読取で交互に得られ、読取光学系のＭＴＦ周波数特性
に依存して周波数の大小により低い周波数では再生レベ
ルが大きく、高い周波数では再生レベルが低くなる再生
信号を交互に生ずる。(Function) According to the configuration of the present invention, a low-frequency information reproduction signal and a high-frequency information reproduction signal are alternately obtained by optical reading of recorded information, and the information reproduction signal depends on the MTF frequency characteristics of the reading optical system. Depending on the magnitude of the frequency, reproduction signals are alternately generated in which the reproduction level is high at low frequencies and low at high frequencies.

また、再生信号のデユーティ比による変化を見ると、同
じ情報ビットの変動分、例えば周波数の大小に応じて径
の異なる情報ビットの同じ径の変化について、情報ビッ
トが大きい方（低い周波数）の再生信号のデユーティ比
の変化は小さく、逆に情報ビットの小さい方（高い周波
数〉の再生信号のデユーティ比の変化は大きくなる。そ
こで、デユーティ比の変化が少ない周波数の低い情報ビ
ットから得られる再生信号を基準として、デユーティ比
の変化が大きい周波数の高い情報ビットから得られた再
生信号の二次量に起因した変動を検出する。Also, looking at the changes due to the duty ratio of the reproduced signal, we can see that for the variation of the same information bit, for example, the change in the same diameter of information bits with different diameters depending on the magnitude of the frequency, the reproduction of the one with the larger information bit (lower frequency) The change in the duty ratio of the signal is small, and conversely, the change in the duty ratio of the reproduced signal of the smaller information bit (higher frequency) is larger. Using this as a reference, fluctuations caused by the secondary amount of the reproduced signal obtained from high-frequency information bits with large changes in duty ratio are detected.

更に、デユーティ比５０％からの変化に対し基準となる
低い周波数の情報再生信号のレベル変化はほとんどない
が、高い周波数の情報再生信号については、デユーティ
比が小さくなると、直流成分が減少し、逆にデユーティ
比が大きくなると直流成分が増加する。そのため低い周
波数の情報再生信号の振幅中心レベルを基準に見ると、
高い周波数の情報再生信号はデユーティ比の減少で下側
にシフトし、デユーティ比の増加で上側にシフトするレ
ベル変化を起こす。Furthermore, when the duty ratio changes from 50%, there is almost no change in the level of the reference low-frequency information reproduction signal, but as for the high-frequency information reproduction signal, as the duty ratio decreases, the DC component decreases, and the opposite effect occurs. When the duty ratio increases, the DC component increases. Therefore, when looking at the amplitude center level of the low frequency information reproduction signal as a reference,
The high frequency information reproduction signal causes a level change in which it shifts downward as the duty ratio decreases, and shifts upward as the duty ratio increases.

そこで本発明にあっては、再生信号が振幅中心レベルに
対しデユーティ比に依存してシフトできるように交流結
合した後に振幅中心レベルの上側と下側に分けて個別に
包絡線検波する。Therefore, in the present invention, after the reproduced signal is AC-coupled so that it can be shifted with respect to the amplitude center level depending on the duty ratio, envelope detection is performed separately for above and below the amplitude center level.

この包絡線検波による上側検波信号と下側検波信号との
間には、デユーティ比が５０％であれば振幅成分が等し
く、デユーティ比が小さくなれば上側検波信号の振幅成
分が下側検波信号の振幅成分より大きくなり、更にデユ
ーティ比が大きくなると、逆に上側が下側に対し振幅成
分が小さくなる関係を生ずる。If the duty ratio is 50%, the amplitude components are equal between the upper detection signal and the lower detection signal by envelope detection, and if the duty ratio becomes smaller, the amplitude component of the upper detection signal will be the same as that of the lower detection signal. When the amplitude component becomes larger and the duty ratio further increases, a relationship occurs in which the upper side has a smaller amplitude component than the lower side.

そのため各包絡線検波出力を帯域フィルタを通すことで
振幅成分を抽出して正弦波とした後に振幅ピーク値を検
出し、この検出ピーク値の大小比較から二次量の有無、
二次量を生じたときのデユーティ比５０％に対する大小
関係を判断するようにしたものである。Therefore, each envelope detection output is passed through a bandpass filter to extract the amplitude component and make it into a sine wave, and then the amplitude peak value is detected. By comparing the magnitude of the detected peak value, the presence or absence of a secondary quantity can be determined.
The magnitude relationship with respect to a duty ratio of 50% when a secondary quantity is generated is determined.

（実施例） 第１図は本発明の一実施例を示したブロック図である。(Example) FIG. 1 is a block diagram showing one embodiment of the present invention.

まず構成を説明すると、１は読取ヘッドでおり、記録媒
体としての光ディスク１ａにレーザービーム等の照射で
成る記録信号により書き込まれた記録情報を光学的に読
取って電気信号に変換し、情報再生信号を出力する。First, to explain the configuration, reference numeral 1 denotes a reading head, which optically reads recorded information written on an optical disk 1a as a recording medium by a recording signal formed by irradiation with a laser beam, converts it into an electric signal, and generates an information reproduction signal. Output.

ここで、記録情報の二次量を検出するために光ディスク
１ａに書き込まれる情報ビットとしては、２つの異なっ
た周波数を有する情報ビットをデユーティ比５０％を予
定した同一の時間毎に交互に記録し、二次量を検出する
際にはこの２つの異なつた周波数を有する情報ビットを
同一時間毎に交互に記録した部分を再生するようになる
。Here, as the information bits written on the optical disc 1a to detect the secondary amount of recorded information, information bits having two different frequencies are recorded alternately at the same time with a scheduled duty ratio of 50%. , when detecting a secondary quantity, a portion in which information bits having two different frequencies are recorded alternately at the same time is reproduced.

二次量を検出するために光ディスク１ａに記録する情報
ビットを具体的に説明すると、例えば第２図（ａ）に示
す周波数の低い記録信号と、第２図（ｂ）に示す周波数
の高い記録信号を記録する。To specifically explain the information bits recorded on the optical disc 1a to detect the secondary quantity, for example, a low frequency recording signal shown in FIG. 2(a) and a high frequency recording signal shown in FIG. 2(b) Record the signal.

ここで第２図（ｂ）に示す周波数の高い信号のビット長
を王とすると、第２図（ａ＞に示す周波数の低い信号の
ビット長は２Ｔ１．：設定される。勿論、ビット長２Ｔ
、Ｔを持つ各記録信号のデユーティ比はそれぞれ５０％
としているが、記録信号となるレーザーパワーのバラ付
きにより破線で示すようにデユーティ比の変動を生ずる
。ここで、ピッｌ−長２Ｔ、Ｔを有する２つの記録信号
に同じビット長の変動Δ丁が生じたとすると、ビット長
下の周波数の高い信号に比べ、ビット長が２丁となる周
波数の低い信号のデユーティ比はあまり変化しない。従
って、周波数の低いビット長２丁の記録信号のデユーテ
ィ比は信号歪が多少生じても略デユーティ比５０％に維
持され、後の説明で明らかにする二次歪の検出において
、周波数の低いビット長２丁の記録信号を基準信号とし
て用いる。Here, if the bit length of the high frequency signal shown in FIG. 2(b) is taken as the king, the bit length of the low frequency signal shown in FIG. 2(a) is set to 2T1.:Of course, the bit length is 2T.
, the duty ratio of each recording signal with T is 50%.
However, due to variations in the laser power used as the recording signal, the duty ratio varies as shown by the broken line. Here, if the same bit length fluctuation Δt occurs in two recording signals with pitch lengths 2T and T, then a signal with a lower frequency with a bit length of 2 digits will have a lower bit length than a higher frequency signal with a lower bit length. The signal duty ratio does not change much. Therefore, the duty ratio of the recording signal of two bit lengths with low frequency is maintained at approximately 50% even if some signal distortion occurs. Two long recording signals are used as reference signals.

再び、第１図を参照するに、読取ヘッド１で読取られた
二次歪検出のための情報再生信号は、コンデンサＣ１に
よる交流結合をもってアンプ２に入力され、アンプ２で
交流増幅された後、同じく交流結合用のコンデンサＣ２
を介して包絡線検波回路３ａ、３ｂのそれぞれに入力さ
れる。Referring again to FIG. 1, the information reproduction signal for second-order distortion detection read by the reading head 1 is input to the amplifier 2 with AC coupling by the capacitor C1, and after being AC amplified by the amplifier 2, Also capacitor C2 for AC coupling
The signal is inputted to each of the envelope detection circuits 3a and 3b via.

包絡線検波回路３ａはアンプ２より得られた情報再生信
号を振幅中心レベルの上側で包絡線検波し、一方、包絡
線検波回路３ｂは振幅中心レベルの下側で包絡線検波を
行なう。The envelope detection circuit 3a performs envelope detection of the information reproduction signal obtained from the amplifier 2 above the amplitude center level, while the envelope detection circuit 3b performs envelope detection below the amplitude center level.

包絡線検波回路３ａ、３ｂの出力はそれぞれ帯域通過フ
ィルタ４ａ、４ｂに与えられ、帯域通過フ、イルタ４ａ
、４ｂのそれぞれにおいて包絡線検波出力の振幅成分を
抽出すると同時に正弦波信号に変換する。The outputs of the envelope detection circuits 3a and 3b are given to bandpass filters 4a and 4b, respectively.
, 4b, the amplitude component of the envelope detection output is extracted and simultaneously converted into a sine wave signal.

帯域通過フィルタ４ａ、４ｂの出力は振幅検出回路５ａ
、５ｂに与えられ、帯域通過フィルタ４ａ、４ｂを通過
した包絡線検波信号の振幅成分における振幅ピーク値を
それぞれ検出する。The outputs of the bandpass filters 4a and 4b are sent to the amplitude detection circuit 5a.
, 5b, and detects the amplitude peak values of the amplitude components of the envelope detection signals that have passed through the bandpass filters 4a and 4b.

振幅検出回路５ａ、５ｂの出力は検出ピーク値の大小に
基づいて情報再生信号に含まれる二次歪の度合いを判断
する判断手段としての判断ロジック６に与えられる。判
断ロジック６は振幅検出回路５ａで検出された振幅ピー
ク値をｈｌ、振幅検出回路５ｂで検出された振幅検出値
をｈ２とすると、この振幅ピーク値ｈ１．ｈ２に基づい
て次の判断処理を行なう。The outputs of the amplitude detection circuits 5a and 5b are provided to a judgment logic 6 as a judgment means for judging the degree of second-order distortion contained in the information reproduction signal based on the magnitude of the detected peak value. The judgment logic 6 determines that the amplitude peak value h1 . The next judgment process is performed based on h2.

（ａ）ｈ１＝ｈ２のとき； 情報再生信号のデユーティ比は５０％で且つ二次歪を含
まないものと判断する。(a) When h1=h2; It is determined that the duty ratio of the information reproduction signal is 50% and does not include second-order distortion.

（ｂ）ｈｌ＞ｈ２のとき； 情報再生信号のデユーティ比が５０％より小さく、且つ
二次正荷りと判断する。(b) When hl>h2; The duty ratio of the information reproduction signal is smaller than 50% and it is determined to be a secondary positive load.

（Ｃ）ｈｌ＜ｈ２のとぎ： 情報再生信号はデユーティ比が５０％より大きく且つ二
次正荷りと判断する。(C) Interpretation of hl<h2: The information reproduction signal is determined to have a duty ratio greater than 50% and a secondary positive load.

即ち、判断ロジック６は振幅検出回路５ａ、５ｂからの
検出ピーク値ｈ１．ｈ２に基づいて前記（ａ）〜（Ｃ）
の判断条件のもとに対応する出力ａ、ｂ、ｃのいずれか
１つを出力し、例えば判断ロジック６の出力に基づいて
記録信号のレーザーパワーをコントロールする場合、最
適出力ａが得られたときには記録信号のデユーティ比が
５０％となっていることから、レーザーパワーをそのと
きの値に維持し、一方、判断出力すが得られたときには
、記録信号のデユーティ比が小さいことからレーザーパ
ワーを高めて記録信号のデユーティ比を最適出力ａが得
られる５０％に制御し、逆に判断出力Ｃが１ｑられてい
るときには、記録信号のデユーティ比が５０％より大き
いことから、レーザーパワーを下げて最適出力ａが得ら
れるように制御するようになる。That is, the judgment logic 6 uses the detected peak values h1. (a) to (C) above based on h2
For example, when outputting one of the corresponding outputs a, b, and c under the judgment conditions of , and controlling the laser power of the recording signal based on the output of the judgment logic 6, the optimum output a was obtained. Sometimes, the duty ratio of the recording signal is 50%, so the laser power is maintained at the value at that time, while when a judgment output is obtained, the duty ratio of the recording signal is small, so the laser power is kept at that value. When the judgment output C is 1q, the duty ratio of the recording signal is higher than 50%, so the laser power is lowered. Control is performed so that the optimum output a is obtained.

次に、第１図の実施例の作用を説明する。Next, the operation of the embodiment shown in FIG. 1 will be explained.

まず、光ディスク１ａには第２図に示したピッ１〜長２
丁の記録信号（低い周波数）とビット長Ｔの記録信号（
高い周波数）を一定間隔で交互に記録しており、例えば
第３図（ａ＞に示すように、ビット長２丁の記録信号に
続いてビット長Ｔの信号を２つ交互に記録していたもの
とする。First, the optical disc 1a has pitches 1 to 2 as shown in FIG.
A recording signal with a bit length T (low frequency) and a recording signal with a bit length T (
For example, as shown in Figure 3 (a), a recording signal of two bit lengths was followed by two signals of bit length T alternately. shall be taken as a thing.

このように光ディスク１ａに記録された２つの異なる周
波数で成る情報ビットを読取ヘッド１により再生して情
報再生信号を得ると、第１０図に示した読取光学系の検
出感度、即ち記録周波数に対するＭＴＦ特性によりビッ
ト長２丁の再生信号とビット長下の再生信号とでは再生
信号レベルが異なる。When the information bits of two different frequencies recorded on the optical disk 1a are reproduced by the reading head 1 to obtain an information reproduction signal, the detection sensitivity of the reading optical system shown in FIG. 10, that is, the MTF with respect to the recording frequency Depending on the characteristics, the level of the reproduced signal differs between the reproduced signal of two bit lengths and the reproduced signal of the lower bit length.

即ち、ビット長２丁の記録周波数は低いことから第１０
図のＭＴＦ周波数特性から明らかなようにＭＴＦの値が
大きく、その結果、ビット長２Ｔの記録ビットからの情
報再生信号は第４図の信号７に示すように再生レベルが
高くなる。これに対しビット長Ｔの記録信号の周波数は
高いことから、第１０図におけるＭＴＦの値が小さくな
り、第４図の信号８に示すようにビット長２Ｔの再生信
号７に対し再生信号８のように再生レベルが低くなり、
更にピッ１〜長Ｔの再生信号については基本周波数の２
倍以上の周波数成分の信号が光学系から検出できないた
め、略正弦波となる。In other words, since the recording frequency for two bit lengths is low, the 10th
As is clear from the MTF frequency characteristics shown in the figure, the value of MTF is large, and as a result, the reproduction level of the information reproduction signal from the recorded bits of bit length 2T becomes high as shown in signal 7 of FIG. On the other hand, since the frequency of the recording signal with bit length T is high, the value of MTF in FIG. 10 becomes small, and as shown in signal 8 in FIG. The playback level will be lower, as
Furthermore, for the reproduced signal from P1 to long T, the fundamental frequency is 2.
Since the optical system cannot detect signals with frequency components that are twice as high or higher, the signal becomes a substantially sine wave.

そこで、読取光学系におけるＭＴＦ周波数特性により第
３図（ａ）の実線９に示すように、デユーティ比５０％
で記録された情報ビットの情報再生信号は、第３図（ｂ
）に示す信号波形となる。Therefore, due to the MTF frequency characteristics in the reading optical system, the duty ratio is 50%, as shown by the solid line 9 in Fig. 3(a).
The information reproduction signal of the information bits recorded in FIG.
) is the signal waveform shown.

このデユーティ比５０％のときの信号波形はビット長２
丁及びビット長下のいずれの信号についても、中心レベ
ル１２に対し上下に対称な再生信号波形となる。The signal waveform when the duty ratio is 50% is bit length 2.
For both signals of 1 and 1 bit length, the reproduced signal waveforms are vertically symmetrical with respect to the center level 12.

次に、第３図（ａ）に点線で示すデユーティ比が５０％
より小さい記録信号１０で記録された情報ビットからの
情報再生信号は、第３図（Ｃ）に示すようになる。即ち
、ビット長２Ｔの再生信号についてはデユーティ比変動
分による影響をほとんど受けないことから中心レベル１
２の上下に対称な波形となるが、ビット長Ｔの再生信号
についてはデユーティ比が５０％より小さくなることで
直流成分が減少し、中心レベル１２の上側の振幅成分が
減少すると同時に下側の振幅成分が増加した波形となる
。Next, the duty ratio shown by the dotted line in Fig. 3(a) is 50%.
The information reproduction signal from the information bits recorded with the smaller recording signal 10 is as shown in FIG. 3(C). In other words, since the reproduced signal with a bit length of 2T is hardly affected by the duty ratio fluctuation, the center level is 1.
2, the waveform is symmetrical above and below, but for the reproduced signal with bit length T, when the duty ratio becomes smaller than 50%, the DC component decreases, and the upper amplitude component of center level 12 decreases, while at the same time the lower amplitude component decreases. The resulting waveform has an increased amplitude component.

更に、第３図（ａ）に一点鎖線で示すように、記録信号
のデユーティ比が５０％より大きくなった記録信号１１
で記録された情報ビットの情報再生信号は、第３図（ｄ
＞に示すようになる。即ち、ピッ［・長２丁の再生信号
についてはデユーティ比の増加による変動がほとんどな
いことから、中心レベル１２の上下に略対称な波形とな
るが、ビット長下の再生信号はデユーティ比の増加で直
流成分が増加し、中心レベル１２の上側の振幅が増加し
逆に中心レベル１２の下側の振幅が減少するようになる
。Furthermore, as shown by the dashed line in FIG. 3(a), the recording signal 11 whose duty ratio is greater than 50%
The information reproduction signal of the information bits recorded in FIG.
> is shown. In other words, the reproduced signal with a bit length of 2 bits has almost no fluctuation due to an increase in the duty ratio, so the waveform is approximately symmetrical above and below the center level 12, but the reproduced signal with a lower bit length changes as the duty ratio increases. , the DC component increases, the amplitude above the center level 12 increases, and conversely the amplitude below the center level 12 decreases.

実際には第１図に示したように、コンデンサＣ１、Ｃ２
で交流結合しているため、ビット長２Ｔの再生信号とビ
ット長下の再生信号の直流成分の大きざが異なるとき、
第５図に示すようにビット長２Ｔの再生信号の中心レベ
ル１２ａとビット長Ｔの再生信号の中心レベル１２ｂと
の間にはサグ１３が生じている。このサグが生じている
間に検出しなければならない。従って、ビット長２王の
信号とビット長Ｔの信号を記録する周期τはあまり大き
くすることはできない。尚、本実施例では、ビット長２
丁の信号とＴの信号を記録する時間は、双方向同一時間
（それぞれτ／２ずつ）であるが、これは最終的な検出
信号が大きくとれるからである。よって、必ずしも同一
時間である必要はない。Actually, as shown in Fig. 1, capacitors C1 and C2
Because AC coupling is performed at
As shown in FIG. 5, a sag 13 occurs between the center level 12a of the reproduced signal with bit length 2T and the center level 12b of the reproduced signal with bit length T. This sag must be detected while it is occurring. Therefore, the cycle τ for recording a signal with a bit length of 2 kings and a signal with a bit length T cannot be made very large. Note that in this embodiment, the bit length is 2.
The time for recording the D signal and the T signal is the same in both directions (τ/2 each), and this is because the final detected signal can be large. Therefore, they do not necessarily have to be at the same time.

このように読取ヘッド１の読取光学系を介して再生され
る情報再生信号の二次歪検出につき、例えば第３図（Ｃ
）に示すようにデユーティ比が、５０％より小さいとき
の情報再生信号を例にとって具体的に説明する。Regarding the second-order distortion detection of the information reproduction signal reproduced through the reading optical system of the reading head 1, for example, FIG.
), the information reproduction signal when the duty ratio is smaller than 50% will be specifically explained.

読取ヘッド１で再生されたデユーティ比が５０％より小
さいときの情報再生信号はアンプ２で交流増幅された後
、包絡線検波回路３ａ、３ｂに与えられ、包絡線検波回
路３ａは第６図（ａ）に示す上側包絡線の検波出力を生
じ、一方、包絡線検波回路３ｂは第６図（ｂ）に示す下
側包絡線の検波出力を生ずる。The information reproduction signal reproduced by the reading head 1 when the duty ratio is smaller than 50% is AC amplified by the amplifier 2 and then applied to the envelope detection circuits 3a and 3b. The detection output of the upper envelope shown in a) is produced, while the envelope detection circuit 3b produces the detection output of the lower envelope shown in FIG. 6(b).

この第６図に示す上側及び下側の包絡線検波信号におい
て、振幅の大きい部分はビット長２Ｔの再生信号を表し
、振幅成分の小さい部分がビット長Ｔの再生信号を表す
。In the upper and lower envelope detection signals shown in FIG. 6, a portion with a large amplitude component represents a reproduced signal with a bit length of 2T, and a portion with a small amplitude component represents a reproduced signal with a bit length T.

包絡線検波回路３ａ、３ｂで包絡線検波された上側及び
下側の包絡線検波信号は帯域通過フィルタ４ａ、４ｂに
入力される。ここで、帯域通過フィルタ４ａ、４ｂの中
心周波数ｆｃはｆｃ＝１／τに設定されており、帯域フ
ィルタ４ａを通過した第９図（ａ）に示す上側包絡線検
波信号は、第７図（ａ）に示す振幅成分を抽出し且つ正
弦波に変換された信号となり、一方、第６図（ｂ）に示
す下側包絡線検波信号は、第７図（ｂ）に示すように振
幅成分を抽出し且つ正弦波信号に変換された信号となる
。The upper and lower envelope detection signals subjected to envelope detection by the envelope detection circuits 3a and 3b are input to band pass filters 4a and 4b. Here, the center frequency fc of the bandpass filters 4a and 4b is set to fc=1/τ, and the upper envelope detection signal shown in FIG. 9(a) that has passed through the bandpass filter 4a is as shown in FIG. The amplitude component shown in a) is extracted and converted into a sine wave, while the lower envelope detection signal shown in FIG. 6(b) has the amplitude component extracted as shown in FIG. 7(b). The signal is extracted and converted into a sine wave signal.

この帯域通過フィルタ４ａ、４ｂを通過することで得ら
れた第７図（ａ）、（ｂ）に示す上側包絡線検波出力の
振幅成分及び下側包絡線検波信号の振幅成分は振幅検出
回路５ａ、５ｂのそれぞれにおいて１辰幅ピーク値ｈ１
．ｈ２が検出され、判断ロジック６において検出ピーク
値ｈ１．ｈ２の大小関係に基づいて二次歪の有無の検出
及びデユーティ比の５０％からのずれを判断する。The amplitude component of the upper envelope detection output and the amplitude component of the lower envelope detection signal shown in FIGS. 7(a) and 7(b) obtained by passing through the band pass filters 4a and 4b are obtained by the amplitude detection circuit 5a. , 5b, the 1-darin width peak value h1
．． h2 is detected, and in the judgment logic 6, the detected peak value h1. Based on the magnitude relationship of h2, the presence or absence of secondary distortion is detected and the deviation of the duty ratio from 50% is determined.

即ち、第７図の場合にはｈｌ＞ｈ２でおることから、二
次子を生じており、且つデユーティ比が５０％より小さ
いとする判断出力すを生ずることになる。That is, in the case of FIG. 7, since hl>h2, a secondary child is generated and a judgment output that the duty ratio is smaller than 50% is generated.

勿論、第３図（ｄ）に示ずように、デユーティ比が５０
％より大ぎいときには振幅検出回路５ａ。Of course, as shown in FIG. 3(d), the duty ratio is 50.
%, the amplitude detection circuit 5a.

５ｂから得られる検出ピーク値ｈ”ｌ、ｈ２は、ｈｌ＜
ｈ２となることから、判断ロジック６は二次子の発生を
判断すると同時にデユーティ比が５０％より大きいとな
る判断出力Ｃを生ずる。更に、デユーティ比が５０％の
どきにはｈｌ、＝ｈ２であり、このときは最適出力ａを
生ずるようになる。The detected peak values h”l and h2 obtained from 5b are hl<
h2, the determination logic 6 determines the occurrence of a secondary child and at the same time generates a determination output C in which the duty ratio is greater than 50%. Further, when the duty ratio is 50%, hl,=h2, and in this case, the optimum output a is produced.

尚、上記の実施例にあっては、光ディスクに記録したヒ
ツト長２ＴとピッＩ〜長Ｔの情報ビットの情報再生信号
を例にとるものであったが、周波数の異なる２つの記録
ピッｌ−情報の差を大きくする程、二次子の検出精度も
よくなることから、第１０図に示したＭＴＦ周波数特性
の範囲内で周波数の異なる記録信号のピッ１〜長の差を
大ぎくすることが望ましい。In the above embodiment, the information reproduction signal of the hit length 2T and the information bits of the pitch I to length T recorded on the optical disk was taken as an example, but the information reproduction signal of the information bits of the pitch I to length T recorded on the optical disk was taken as an example. The larger the difference in information is, the better the detection accuracy of secondary elements becomes. Therefore, it is possible to greatly increase the difference in pitch 1 to length of recording signals with different frequencies within the range of the MTF frequency characteristics shown in Figure 10. desirable.

また、上記の実施例は二次子の検出に基づいて記録信号
となるレーザーパワーのコン１−・ロールを例にとるも
のであったが、本発明はこれに限定されず、単なる二次
子の検出及びデユーディ比の測定に使用してもよく、若
１ノくは二次子あるいはデユーティ比の検出出力に基づ
く適宜の自動制御を行なうようにしてもよい。Further, although the above embodiment takes as an example the control of the laser power which becomes a recording signal based on the detection of a secondary child, the present invention is not limited to this, and the present invention is not limited to this. It may be used for the detection of the first or second order or the duty ratio, and appropriate automatic control may be performed based on the detection output of the first or second order or the duty ratio.

上記実施例によれば、包絡線検波回路（３ａ。According to the above embodiment, the envelope detection circuit (3a).

３ｂ）の出力を帯域通過フィルタ（４ａ、４ｂ）を介し
た後、振幅検出回路（５ａ、５ｂ）で振幅を検出し、双
方の振幅の差を判断ロジック６で判断するものを示（）
たが、本発明はこれ【こ限られず、例えば半波整流回路
の出力をコンデンサで平滑して直流レベルを比較判定す
るよう構成することができる。3b) is passed through the band pass filter (4a, 4b), the amplitude is detected by the amplitude detection circuit (5a, 5b), and the difference between the two amplitudes is judged by the judgment logic 6 ().
However, the present invention is not limited to this; for example, the output of the half-wave rectifier circuit may be smoothed with a capacitor and the DC level may be compared and determined.

第１１図は第１図における包絡線検波回路を半波整流回
路２０と平滑回路２１で構成する例で、第１２図は上記
回路の各部における信号波形を示す図でおる。１２は信
号の振幅中心レベル、３１は半波整流回路２０の出力波
形、３２は平滑回路２１の出力波形である。FIG. 11 shows an example in which the envelope detection circuit in FIG. 1 is composed of a half-wave rectifier circuit 20 and a smoothing circuit 21, and FIG. 12 is a diagram showing signal waveforms at various parts of the circuit. 12 is the amplitude center level of the signal, 31 is the output waveform of the half-wave rectifier circuit 20, and 32 is the output waveform of the smoothing circuit 21.

要するに本発明は再生情報信号の周波数による振幅の差
を振幅中心レベルの上側と下側とでそれぞれに検出し、
その大小関係を判定するよう構成する。本発明は回転す
る円盤状媒体のみならず、例えば直線移動するカード状
媒体にも適用することができ、媒体の形状に限定されな
い。In short, the present invention detects the difference in amplitude depending on the frequency of the reproduced information signal above and below the amplitude center level, respectively.
It is configured to determine the magnitude relationship. The present invention can be applied not only to rotating disc-shaped media but also, for example, to linearly moving card-shaped media, and is not limited to the shape of the media.

（発明の効果） 以上説明してきたように本発明によれば、光ディスク等
に対する記録信号のデユ−ティ比が５０％から変化した
ことによる情報再生信号の直流成分の変化に基づいて二
次子を簡単に検出することができ、且つ二次子の検出と
同時にデユーティ比が二次子を生じない５０％であるか
、デユーティ比５０％より大きいか小さいかを判断でき
るため、例えば従来のスペクトルアナライザーによる二
次歪検出では困難でおった記録時のレーザーパワーの補
正も可能とすることができる。(Effects of the Invention) As explained above, according to the present invention, the secondary child is generated based on the change in the DC component of the information reproduction signal caused by the change in the duty ratio of the recording signal for the optical disk etc. from 50%. It can be easily detected, and at the same time as detecting a secondary, it can be judged whether the duty ratio is 50%, which does not produce a secondary, or whether it is larger or smaller than 50%, so for example, a conventional spectrum analyzer It is also possible to correct the laser power during recording, which is difficult to do with second-order distortion detection.

【図面の簡単な説明】[Brief explanation of the drawing]

第１図は本発明の一実施例を示したブロック図、第２図
は二次歪検出対象とする２つの周波数の異なる記録信号
の説明図、第３図は記録信号のデユーティ比を５０％、
５０％より小、５０％より大としたときの情報再生信号
を示した信号波形図、第４図は読取光学系統のＭＴＦ周
波数特性による再生信号のレベル変化を示した信号波形
図、第５図は直流成分の相違により生ずる再生信号のザ
ブを示した信号波形図、第６図は第１図の包絡線検波信
号の波形説明図、第７図は第１図の帯域フィルタの出力
を示した信号波形図、第８図は記録信号のデユーティ比
の変化を示した信号波形図、第９図は従来のスペクトル
アナライザーにより得られる基本周波数に対するスペク
トル成分を示したスペクトル分布図、第１０図は読取光
学系統のＭＴＦ周波数特性を示したグラフ図、第１１図
は他の実施例を示した回路ブロック図、第１２図はその
信号波形図である。 １：読取ヘッド １ａ：光ディスク ２：アンプ ３ａ、３ｂ：包絡線検波回路 ４ａ、４ｂ：帯域通過フィルタ ５ａ、５ｂ：振幅検出回路 ６：判断ロジック（判断手段）Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is an explanatory diagram of recording signals with two different frequencies that are subject to secondary distortion detection, and Fig. 3 shows the duty ratio of the recording signal set to 50%. ,
Fig. 4 is a signal waveform diagram showing the information reproduction signal when it is smaller than 50% and larger than 50%. Fig. 4 is a signal waveform diagram showing the level change of the reproduction signal due to the MTF frequency characteristics of the reading optical system. Fig. 5 is a signal waveform diagram showing dips in the reproduced signal caused by differences in DC components, Figure 6 is an explanatory diagram of the waveform of the envelope detection signal in Figure 1, and Figure 7 is the output of the bandpass filter in Figure 1. Signal waveform diagram. Figure 8 is a signal waveform diagram showing changes in the duty ratio of the recorded signal. Figure 9 is a spectral distribution diagram showing spectral components with respect to the fundamental frequency obtained by a conventional spectrum analyzer. Figure 10 is a reading diagram. FIG. 11 is a graph diagram showing the MTF frequency characteristics of the optical system, FIG. 11 is a circuit block diagram showing another embodiment, and FIG. 12 is a signal waveform diagram thereof. 1: Reading head 1a: Optical disk 2: Amplifiers 3a, 3b: Envelope detection circuits 4a, 4b: Bandpass filters 5a, 5b: Amplitude detection circuit 6: Judgment logic (judgment means)

Claims (3)

【特許請求の範囲】[Claims] （１）２つの異なった周波数による、デューティ比５０
％を予定した２値情報を交互に記録した記録媒体の記録
情報を光学的に読取って電気信号に変換する読取手段と
；該読取手段の出力信号を交流増幅する交流増幅手段と
；該交流増幅手段の出力の振幅中心レベルの上側と下側
で記録情報周波数に基づいて生ずる振幅差をそれぞれ検
出する２つの振幅差検出手段と；該２つの振幅差検出手
段の出力の比較によって前記記録情報に含まれる二次歪
の有無及び極性を判定する判定手段と；を備えたことを
特徴とする光学式記録情報の二次歪検出装置。(1) Duty ratio 50 with two different frequencies
reading means for optically reading recorded information on a recording medium on which binary information with a predetermined % is alternately recorded and converting it into an electrical signal; AC amplifying means for AC amplifying the output signal of the reading means; two amplitude difference detection means for respectively detecting an amplitude difference that occurs based on the recorded information frequency above and below the amplitude center level of the output of the means; and by comparing the outputs of the two amplitude difference detection means, A second-order distortion detection device for optically recorded information, comprising: determining means for determining the presence or absence and polarity of included second-order distortion. （２）前記振幅差検出手段は包絡線検波手段を含むこと
を特徴とする特許請求の範囲第１項記載の光学式記録情
報の二次歪検出装置。(2) The second-order distortion detection device for optically recorded information according to claim 1, wherein the amplitude difference detection means includes an envelope detection means. （３）前記振幅差検出手段は半波整流手段を含むことを
特徴とする特許請求の範囲第１項記載の光学式記録情報
の二次歪検出装置。(3) The second-order distortion detection device for optically recorded information according to claim 1, wherein the amplitude difference detection means includes a half-wave rectification means.
JP62007734A 1987-01-16 1987-01-16 Apparatus for detecting secondary distortion of recording signal and optical recording apparatus Expired - Lifetime JP2600659B2 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
JP62007734A JP2600659B2 (en) 1987-01-16 1987-01-16 Apparatus for detecting secondary distortion of recording signal and optical recording apparatus
US07/379,224 US4979162A (en) 1987-01-16 1989-07-13 Apparatus for detecting the secondary distortion of optical type recorded information

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP62007734A JP2600659B2 (en) 1987-01-16 1987-01-16 Apparatus for detecting secondary distortion of recording signal and optical recording apparatus

Publications (2)

Publication Number Publication Date
JPS63177318A true JPS63177318A (en) 1988-07-21
JP2600659B2 JP2600659B2 (en) 1997-04-16

Family

ID=11673933

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Application Number Title Priority Date Filing Date
JP62007734A Expired - Lifetime JP2600659B2 (en) 1987-01-16 1987-01-16 Apparatus for detecting secondary distortion of recording signal and optical recording apparatus

Country Status (1)

Country Link
JP (1) JP2600659B2 (en)

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS60131673A (en) * 1983-12-20 1985-07-13 Pioneer Electronic Corp Signal detector
JPS6116070A (en) * 1984-07-02 1986-01-24 Nippon Telegr & Teleph Corp <Ntt> Detector for optical information

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS60131673A (en) * 1983-12-20 1985-07-13 Pioneer Electronic Corp Signal detector
JPS6116070A (en) * 1984-07-02 1986-01-24 Nippon Telegr & Teleph Corp <Ntt> Detector for optical information

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