JPS6145415A - Reading circuit of optical storage device - Google Patents
Reading circuit of optical storage deviceInfo
- Publication number
- JPS6145415A JPS6145415A JP16750584A JP16750584A JPS6145415A JP S6145415 A JPS6145415 A JP S6145415A JP 16750584 A JP16750584 A JP 16750584A JP 16750584 A JP16750584 A JP 16750584A JP S6145415 A JPS6145415 A JP S6145415A
- Authority
- JP
- Japan
- Prior art keywords
- envelope
- circuit
- signal
- readout
- analog 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.)
- Pending
Links
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
- G11B20/10—Digital recording or reproducing
- G11B20/10009—Improvement or modification of read or write signals
- G11B20/10046—Improvement or modification of read or write signals filtering or equalising, e.g. setting the tap weights of an FIR filter
- G11B20/10212—Improvement or modification of read or write signals filtering or equalising, e.g. setting the tap weights of an FIR filter compensation for data shift, e.g. pulse-crowding effects
-
- 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
- G11B7/005—Reproducing
Landscapes
- Engineering & Computer Science (AREA)
- Signal Processing (AREA)
- Signal Processing For Digital Recording And Reproducing (AREA)
- Optical Recording Or Reproduction (AREA)
- Manipulation Of Pulses (AREA)
Abstract
Description
【発明の詳細な説明】
〔技術分野〕
本発明Ｖ′ｉ記は装置の読出し回路に関し、特に光デイ
スク装置などの光記厖装置の読出し回路に関する。DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a reading circuit for an apparatus, and more particularly to a reading circuit for an optical storage apparatus such as an optical disk apparatus.
光デイスク装置などの光記ｔ、！装置では、レーザ光を
光学レンズで極小のスポットに収束させ、この光スポッ
トを記憶媒体上に照射した時に媒体上に形成されたピッ
トの有無に対応して強度が変化する反射光を光センサで
検出して情報の再生が行なわれる。この光センサで検出
された読出しアナログ信号は微弱であるため増幅された
後、比較回路でしきい値と比較され、２値のディジタル
信号である読出しデータに変換される。読出しアナログ
信号は反射光の強弱変化に対応するため本質的に直流成
分をも含んでいるが、広帯域高利得のＤＣ増幅が困難な
こと、光センサをフォーカスあるいはトラッキングサー
ボと共用する関係で周波数帯域を分割する必要から直流
成分と低周波成分がカットされた信号となる。このため
、−例としてデータブロックの始端部では第１図の波形
図に示すようＫ、反射光に対応する読出しアナログ信号
はエンベロープが大きく変動する。Optical records such as optical disk devices,! The device uses an optical lens to converge laser light into a very small spot, and when this light spot is irradiated onto a storage medium, an optical sensor detects the reflected light whose intensity changes depending on the presence or absence of pits formed on the medium. The information is reproduced upon detection. Since the read analog signal detected by this optical sensor is weak, it is amplified, then compared with a threshold value in a comparison circuit, and converted into read data, which is a binary digital signal. The readout analog signal essentially contains a DC component in order to respond to changes in the intensity of reflected light, but it is difficult to amplify broadband high gain DC, and the frequency band is limited due to the fact that the optical sensor is shared with the focus or tracking servo. Since it is necessary to divide the signal, the DC component and low frequency component are cut out. For this reason, for example, at the starting end of a data block, the envelope of the read analog signal corresponding to the reflected light K, as shown in the waveform diagram of FIG. 1, fluctuates greatly.
このような読出しアナログ信号を正しくディジタル信号
に変換するため、従来の読出し回路では、第２図のブロ
ック図に示すように、読出しアナログ信号の低周波成分
をローパスフィルタｌで検出し、これを比較回路２のし
きい値とする。In order to correctly convert such readout analog signals into digital signals, conventional readout circuits detect the low frequency components of the readout analog signals with a low-pass filter l and compare them, as shown in the block diagram of Figure 2. This is the threshold value of circuit 2.
しかし、この従来の回路では第１図に示すデータブロッ
ク始端部、あるいは信号のドロップアウト部のエンベロ
ープ変動に対しては効果はあるが、データの変調コード
に応じて発生するエンベロープ変動には追従出来ない欠
点があった。ちなみに第３図に示すモディファイドＦＭ
（ＭＦＭ）変調方式におけるｔｔｏｔｔｏ・・・データ
の場合、従来回路のしきい値３１は読出しアナログ信号
３２の低周波成分、すなわち、０レベルに対する正極性
波形の面積と負極性波形の面積の差に相当したレベルと
なるため、データの検出位置がＰ−Ｐ振幅の中間値であ
る真のピット位置３３からズレを生じてピットシフトが
発生し％読出しマージンを低下させる大きな要因となっ
ていた。However, although this conventional circuit is effective against envelope fluctuations at the start of the data block or signal dropout shown in Figure 1, it cannot track envelope fluctuations that occur depending on the data modulation code. There were no drawbacks. By the way, the modified FM shown in Figure 3
In the case of ttotto... data in the (MFM) modulation method, the threshold value 31 of the conventional circuit is determined by the low frequency component of the read analog signal 32, that is, the difference between the area of the positive polarity waveform and the area of the negative polarity waveform with respect to the 0 level. As a result, the data detection position deviates from the true pit position 33, which is the intermediate value of the P-P amplitude, causing a pit shift, which is a major factor in reducing the percentage read margin.
本発明の目的は、変調コードに応じて発生するエンベロ
ープ変動にも追従し、読出し時のピットシフトを低減し
、読出しマージンを向上させ得る光記憶装置の読出し回
路を提供することにある。SUMMARY OF THE INVENTION An object of the present invention is to provide a readout circuit for an optical storage device that can follow envelope fluctuations that occur depending on a modulation code, reduce pit shifts during readout, and improve readout margin.
本発明の光記憶装置の読出し回路は、レーザ光を光学レ
ンズで収束させた光スポットを記厖媒体上に照射した時
に媒体上に形成されたピットの有無に対応して強度が変
化する反射光を光センサで検出した読出しアナログ信号
を増幅し、この増幅した読出しアナログ信号を比較回路
でしきい値と比較して２値のディジタル信号である読出
しデータを得る光記憶装置の読出し回路において、前記
読出しアナログ信号の正極性側のエンベロープレベルお
よび負極性側のエンベロープレベルヲ検出するエンベロ
ープ検出回路と、前記正極性エンベロープレベルと前記
負極性エンベロープレベルの算術レベルを前記比較回路
のしきい値とする平均値回路とを有することを特徴とす
るものである。The readout circuit of the optical storage device of the present invention produces reflected light whose intensity changes depending on the presence or absence of pits formed on the recording medium when a light spot made by converging a laser beam with an optical lens is irradiated onto the recording medium. A readout circuit of an optical storage device that amplifies a readout analog signal detected by an optical sensor and compares the amplified readout analog signal with a threshold value in a comparison circuit to obtain readout data that is a binary digital signal. an envelope detection circuit that detects a positive envelope level and a negative envelope level of a read analog signal; and an average that uses an arithmetic level of the positive envelope level and the negative envelope level as a threshold value of the comparison circuit. It is characterized by having a value circuit.
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４図は本発明の一実施例を示す回路構成図であシ、２
は比較回路、３は読出し光ヘッド、４は増幅回路、５は
正極性エンベロープ検出回路、６は負極性エンベロープ
検出回路、７は平均値回路である。なお、８，１２’、
１３，１７はコンデンサ、９，１４．１８〜２１は抵抗
、１０．１５はダイオ−ド、１１はＮＰＮトランジスタ
、１６はＰＮＰ）ランジスタである。第５図は第４図の
動作を示す波形図である。FIG. 4 is a circuit configuration diagram showing one embodiment of the present invention.
3 is a comparison circuit, 3 is a reading optical head, 4 is an amplifier circuit, 5 is a positive polarity envelope detection circuit, 6 is a negative polarity envelope detection circuit, and 7 is an average value circuit. In addition, 8, 12',
13, 17 are capacitors, 9, 14, 18-21 are resistors, 10.15 are diodes, 11 is an NPN transistor, and 16 is a PNP transistor. FIG. 5 is a waveform diagram showing the operation of FIG. 4.
読出し光ヘッド３により再生されだ読出しアナログ信号
３２は増幅回路４で増幅され、比較回路 ・２の一方
の入力となるとともに、正極性エンベロープ検出回路５
と負極性エンベロープ検出回路６にも入力される。正極
性エンベロープ検出回路５ではＮＰＮ）ランジスタ１１
の検波作用とコンデンサ１２の電圧ホールド作用で読出
しアナログ信号３２の正極性側のピーク値のエンベロー
プレベルが検出され正極性エンベローブ出力５１が得ら
れる。同様に負極性エンベロープ検出回路６ではＰＮＰ
トランジスタ１６とコンデンサ１７１Ｃよシ読出しアナ
ログ信号３２の負極性側のピーク値のエンベロープレベ
ルカ検出すレ負極性エンヘロープ出力５２が得られる。The readout analog signal 32 reproduced by the readout optical head 3 is amplified by the amplifier circuit 4 and becomes one input of the comparison circuit 2, as well as the positive polarity envelope detection circuit 5.
is also input to the negative polarity envelope detection circuit 6. In the positive polarity envelope detection circuit 5, the NPN) transistor 11
The envelope level of the peak value on the positive polarity side of the read analog signal 32 is detected by the detection action of and the voltage hold action of the capacitor 12, and a positive polarity envelope output 51 is obtained. Similarly, in the negative polarity envelope detection circuit 6, PNP
By detecting the envelope level of the peak value on the negative polarity side of the read analog signal 32 by the transistor 16 and the capacitor 171C, a negative polarity envelope output 52 is obtained.
なお、両エンベロープ検出回路におけるコンデンサ８，
１３は直流的な結合をカットするだめに用いられ、抵抗
９，１４゜２１とダイオード１０．１５はトランジスタ
１１゜１６にバイアスを供給するだめのものである。In addition, capacitor 8 in both envelope detection circuits,
13 is used to cut DC coupling, and resistors 9, 14.21 and diodes 10.15 are used to supply bias to the transistor 11.16.
次に、正極性エンベロープ出力５１と負極性エンベロー
プ出力５２は平均値回路７に供給され、ここで両者の算
術平均値に相当した平均エンベロープ信号５３が作成さ
れる。すなわち、平均値回路７における抵抗１８．Ｌ９
は同一の値であシ、抵抗２０は抵抗１８．１９に比べ十
分大きな値に定数設定されているため、平均エンベロー
プ信号５３は出力５１．５２の平均値となる。この平均
エンペローブ信号５３がしきい値として比較回路２の他
方の入力端に供給されているだめ、比較回路２では読出
しアナログ信号３２との比較が行なわれ、ディジタル信
号である読出しデータが得ら ４゜れる。Next, the positive envelope output 51 and the negative envelope output 52 are supplied to an average value circuit 7, where an average envelope signal 53 corresponding to the arithmetic mean value of both is created. That is, the resistance 18. in the average value circuit 7. L9
are the same value, and the resistor 20 is set to a constant value sufficiently larger than the resistor 18.19, so the average envelope signal 53 becomes the average value of the output 51.52. Since this average envelope signal 53 is supplied as a threshold value to the other input terminal of the comparator circuit 2, the comparator circuit 2 performs a comparison with the read analog signal 32 and obtains read data which is a digital signal. I can do it.
以上の実施例によれば比較回路のしきい値が、第５図で
示したデータブロック始端部で発生する読出しアナログ
信号のエンベロープ変動に追従するとともに、第３図で
示した変調コードに応じて発生するエンベロープ変動に
も追従するため、常に正しいレベルで読出しアナログ信
号との比較が行なわれ、読出しデータのピットシフトを
低減する仁とができる。According to the above embodiment, the threshold value of the comparator circuit follows the envelope fluctuation of the read analog signal that occurs at the beginning of the data block shown in FIG. Since it also follows the envelope fluctuations that occur, comparison with the read analog signal is always performed at the correct level, making it possible to reduce pit shifts in the read data.
本発明は以上説明したように、読出しアナログ信号をデ
ィジタル信号に変換する比較回路のしきい値として正、
負エンベロープレベルの平均値を用いることによシ、デ
ータブロック始端部あるいは変調コードに応じて発生す
るエンベロープ変動の影響を受けなくなるため、読出し
データのピットシフトが低減し、読出しマージンを向上
させる効果がある。As explained above, the present invention uses positive,
By using the average value of the negative envelope level, it is no longer affected by envelope fluctuations that occur depending on the start of the data block or modulation code, which reduces pit shifts in the read data and improves the read margin. be.
第１図は一般の光記厖装置の読出し回路における読出し
アナログ信号を示す波形図、第２図は従来例を示す回路
図、第３図は第２図の動作を示す波形図、第４図は本発
明の一実施例を示す回路図。
第５図は第４図の動作を示す波形図である。
■・・・・・・ローパスフィルタ、２・・・・・・比較
回路、３・・・・・・読出し光ヘッド、４・・・・・・
増幅回路、５・・・・・・正極性エンベロープ検出回路
、６・・・・・・負極性エンベロープ検出回路、７・・
−・・・平均値回路、８，１２゜１３．１７・・・・・
・コンデンサ、９，１４．１８〜２１・・・・・・抵抗
％ １０，１５・・・・・・ダイオード、１１・・・・
・・ＮＰＮ）ランジスタ、１６・・・・・・ＰＮＰトラ
ンジスタ。
キーｆ１
’？−Ｚ回
Ｊ乙
卒引田
黛ｇ男Fig. 1 is a waveform diagram showing the readout analog signal in the readout circuit of a general optical storage device, Fig. 2 is a circuit diagram showing a conventional example, Fig. 3 is a waveform diagram showing the operation of Fig. 2, and Fig. 4 1 is a circuit diagram showing an embodiment of the present invention. FIG. 5 is a waveform diagram showing the operation of FIG. 4. ■...Low pass filter, 2...Comparison circuit, 3...Reading optical head, 4...
Amplifier circuit, 5... Positive polarity envelope detection circuit, 6... Negative polarity envelope detection circuit, 7...
-...Average value circuit, 8,12°13.17...
・Capacitor, 9,14.18~21...Resistance% 10,15...Diode, 11...
...NPN) transistor, 16...PNP transistor. Key f1'? -Z episode J Otsu graduate Mayuzumi Hikita g-man
Claims (1)
体上に照射した時に媒体上に形成されたピットの有無に
対応して強度が変化する反射光を光センサで検出した読
出しアナログ信号を増幅し、この増幅した読出しアナロ
グ信号を比較回路でしきい値と比較して２値のディジタ
ル信号である読出しデータを得る光記憶装置の読出し回
路において、前記読出しアナログ信号の正極性側のエン
ベロープレベルおよび負極性側のエンベロープレベルを
検出するエンベロープ検出回路と、前記正極性エンベロ
ープレベルと前記負極性エンベロープレベルの平均レベ
ルを前記比較回路のしきい値とする平均値回路とを有す
ることを特徴とする光記憶装置の読出し回路。When a light spot made by converging a laser beam with an optical lens is irradiated onto a storage medium, an optical sensor detects the reflected light whose intensity changes depending on the presence or absence of pits formed on the medium, and amplifies the readout analog signal. In the readout circuit of the optical storage device which obtains readout data which is a binary digital signal by comparing the amplified readout analog signal with a threshold value in a comparator circuit, the envelope level of the positive polarity side and the negative polarity of the readout analog signal are determined. An optical memory comprising: an envelope detection circuit that detects a positive envelope level; and an average value circuit that uses an average level of the positive envelope level and the negative envelope level as a threshold value of the comparison circuit. Device readout circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16750584A JPS6145415A (en) | 1984-08-10 | 1984-08-10 | Reading circuit of optical storage device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16750584A JPS6145415A (en) | 1984-08-10 | 1984-08-10 | Reading circuit of optical storage device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS6145415A true JPS6145415A (en) | 1986-03-05 |
Family
ID=15850925
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP16750584A Pending JPS6145415A (en) | 1984-08-10 | 1984-08-10 | Reading circuit of optical storage device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6145415A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS648513A (en) * | 1987-07-01 | 1989-01-12 | Hitachi Ltd | Optical disk signal reproducing system |
| JPH01276431A (en) * | 1988-04-27 | 1989-11-07 | Toshiba Corp | Information reproducing device |
| EP0817187A2 (en) * | 1994-05-06 | 1998-01-07 | Discovision Associates | Apparatus and method for retrieving stored data |
| US6542451B1 (en) | 1994-05-06 | 2003-04-01 | Discovision Associates | Retrieving data from a storage device using programmable filter and equalizer |
-
1984
- 1984-08-10 JP JP16750584A patent/JPS6145415A/en active Pending
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS648513A (en) * | 1987-07-01 | 1989-01-12 | Hitachi Ltd | Optical disk signal reproducing system |
| JPH01276431A (en) * | 1988-04-27 | 1989-11-07 | Toshiba Corp | Information reproducing device |
| EP0817187A2 (en) * | 1994-05-06 | 1998-01-07 | Discovision Associates | Apparatus and method for retrieving stored data |
| EP0817188A2 (en) * | 1994-05-06 | 1998-01-07 | Discovision Associates | Apparatus for retrieving data from a storage device |
| EP0817190A2 (en) * | 1994-05-06 | 1998-01-07 | Discovision Associates | Method and apparatus for retrieving data from a storage medium |
| EP0817188A3 (en) * | 1994-05-06 | 2002-03-13 | Discovision Associates | Apparatus for retrieving data from a storage device |
| EP0817187A3 (en) * | 1994-05-06 | 2002-03-13 | Discovision Associates | Apparatus and method for retrieving stored data |
| EP0817190A3 (en) * | 1994-05-06 | 2002-03-13 | Discovision Associates | Method and apparatus for retrieving data from a storage medium |
| EP1288943A2 (en) * | 1994-05-06 | 2003-03-05 | Discovision Associates | Retrieving data from a storage device using programmable filter and equalizer |
| US6542451B1 (en) | 1994-05-06 | 2003-04-01 | Discovision Associates | Retrieving data from a storage device using programmable filter and equalizer |
| EP1288943A3 (en) * | 1994-05-06 | 2012-07-18 | Discovision Associates | Retrieving data from a storage device using programmable filter and equalizer |
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