JP2610765C

JP2610765C -

Info

Publication number: JP2610765C
Authority: JP
Original assignee: デイスコビジョンアソシエーツ
Publication date: 1999-07-12

Description

【発明の詳細な説明】【０００１】【産業上の利用分野】本発明は、記録媒体からディジタル情報を再生するための方法及び装置、より
具体的にはパルス幅変調形式のディジタル情報を再生するための光学式ビデオ・
ディスク再生方法及び装置に関する。【０００２】【従来の技術】ビデオ・ディスク・システムは高い記録効率でディジタル情報を貯蔵するため
に広く使われてくるようになった。情報は、例えば渦巻状のパターンの如く複数
個のほぼ円形で且つ同心の記録トラック中に配列された離隔したマークの連続としてディスク上に通常は記録される。特に効果的な１つのシステムは、ディスク
上において連続して離隔されたマークの各々が、複数ビット(multi-bit)コード
・ブロックを表わし、かつ個々独立に長さが変化し得るようにしたパルス幅変調
形式でディジタル情報を記録してきた。このような従来のシステムでは、相次ぐ
マーク同志の間のスペース、又は相次ぐマークの始端同志の間の間隔は通常一定
に保たれる。すなわち、スペースの長さについては、個々独立には変化し得なか
ったことが理解されるであろう。【０００３】ビデオ・ディスクはディスクを被う薄い金属性の記録層を有するガラス基盤を
含むことが出来、そしてディスク上にディジタル情報を記録する装置は、ディス
クが均一な速度で回転される時、記録されるべきディジタル情報に従って変調さ
れる光ビームの強度でディスク上に書込み光ビームを集束する。光の強度が予定
の閾値を越えた時、非反射のピット即ちマークが記録層に形成されるが、一方、
強度が閾値を越えない時は記録層は影響されない。従って、連続し離隔されたマ
ークの長さは、集束されたビームの強度がこの閾値を越えた持続時間に対応する
。【０００４】記録されたディジタル情報は、隔離されたマークの記録パターンにより変調さ
れた強度を有する反射ビームを発生するために、均一な強度を有する読取り光ビ
ームで、記録された光学ディスクのレプリカを走査することによって再生される
。反射されたビームの強度は対応するマークの長さ、従ってそれが表示する特定
のバイナリ・コード・ブロックを決めるために、予定のレベルを越えた時間長が
測られる。【０００５】【発明が解決しようとする課題】この従来のパルス幅変調技術は比較的高い記録効率でディジタル情報を記録す
るのに効果的であることが証明されているけれども、より高い効率でディジタル
情報を記録するためのシステムが望まれている。本発明の目的は、かかる要望を
満たすとともに、高密度に記録されたディジタル情報を容易に再生できる方法及び装置を提供することにある。【０００６】【発明の概要】本発明は、記録媒体上にディジタル情報を記録し且つ再生するためのシステム
で具体化されている。この記録媒体上において、情報は個々独立に変化し得る離
隔されたマークの連続中に記録されている。各マークの長さは連続した複数ビッ
ト・バイナリ・コード・ブロックのうちの分離した１つを表わす。本発明によれ
ば、相次ぐマーク同志の間の間隔即ちスペースもまた、一連のコード・ブロック
の中の分離されたブロックを表わす個々独立に変化し得る長さをもつ。これによ
りディジタル情報はより高い記録効率で記録媒体上に記録される。【０００７】より具体的に言えば、本発明は、ビデオ信号がほぼ円形で且つ同心円的な連続
したレコード・トラックのディスク状記録体に記録されているビデオ・ディスク
・システムに特定の利用を持っている。記録装置は最初にビデオ信号をディジタ
ル化し且つ既知のデータ圧縮技術を使ってディジタル化された信号を圧縮するた
めに機能する。ディジタル化された信号は同じ長さ又は混合された長さのコード
・ブロックの連続に配列され、そして相継ぐコード・ブロックに従って決定され
る状態の遷移を有するバイナリ変調信号が形成される。良好な実施例に於て、各
コード・ブロックは４個のバイナリ・ビットを含み且つ変調信号の連続状態は１
６側のあるべき個々独立の持続期間を有する。【０００８】変調信号は光強度変調器へ結合され、それは複数ビット・コード・ブロックの
連続に対応する個々の持続時間の間、強度が予定敷値よりも大きい値及び小さい
値と交互になるような態様で書込みビームの強度を変調する。強度変調されたビ
ームは、記録体が規定の速度で回転された時、規定のパターンで、対応する顕微
鏡的なピット即ちマークを形成するために記録体上に集束される。その後、その
記録体は、従来の技術を使ってビデオ・ディスクのレプリカを作るために使用さ
れる。【０００９】記録されたディジタル情報はほぼ均一な強度を有する読取り光ビームで連続す
るトラックを走査することによりディスク・レプリカから再生される。これは、
交互のマーク及びスペースである記録パターンによって変調された強度を有する
反射（又は透過）ビームを生ずる。再生装置は連続するマーク及びスペースの持
続時間を測り且つ夫々が表示する特定のコード・ブロックを決定する。検出され
たコード・ブロックの連続を伸長(decompressing)した後に、もとのアナログ映
像信号を再現することが出来る。【００１０】良好な実施例に於て、連続する記録トラックの各々は個々の映像フレームを記
録するのに使われる。然し乍ら、この特別なパルス幅変調形式は可変長のマーク
及びスペースの記録パターンに帰着するので、各映像フレームを記録するのに必
要とするトラックの長さはトラック全体よりも短いのが通常である。これが起き
た時、残りのトラックは規定の充填コードのマーク及びスペースの交番表示によ
って占められる。【００１１】【実施例】図１を参照すると、ディスク状レコード１１上にディジタル化された映像信号
を記録するための記録装置が示されている。その装置はほぼ均一な強度を有する
書込み光ビーム１５を発生するための書込みレーザ１３と、記録されるべきディ
ジタル化された変調信号に従ってビームの強度を変調するための強度変調器１７
を含んでいる。この装置は更に、レコード上に強度変調されたビームを集束する
ための放射方向に移動しうる対物レンズ（図示せず）と、規定された均一な速度
（例えば1800r.p.m.）でレコードを回転するためのスピンドル・モータ１９とを
含む。従って集束されたビームは実質的に円形で且つ同心的な記録トラックを記
録媒体中に形成する。【００１２】記録体１１はそれを被う金属性の記録層を有するガラス基盤を含み、且つ集束ビームは、その強度が予定閾値を越えた時はいつでも記録層中に顕微鏡的なピッ
トを形成する。その強度は記録されるべきディジタル変調信号に従って交互にこ
の閾値よりも大きく及び小さくなるように変調されるので、離隔されたピット即
ちマークの対応する連続がレコード中に形成される。【００１３】本発明に従って、相次ぐマーク及び相次ぐマーク間のスペースの両方が連続し
た複数ビット・バイナリ・コード・ブロックを表わす個々独立に変化し得る長さ
を有するようにした特別なパルス幅変調形式で記録体１１に記録される。これに
よりディジタル情報が改良された記録効率で記録体上に記録される。【００１４】より詳細に言えば、図１の記録装置は、線２３上のベースバンド映像信号をサ
ンプルし、且つ対応するディジタル信号へ映像信号を変換するためのアナログ／
ディジタル変換器２１を含む。このディジタル信号は、垂直及び水平同期信号の
除去、及びディジタル情報の圧縮のため、線２５を経てフォーマッタ２７へ結合
されて、圧縮されたデータを連続した４−ビット・コード・ブロックに形式化す
る。これ等の連続したコード・ブロックは線２９を経て適当な貯蔵バッファ３１
へ転送され、バッファ３１はマーク(MARK)パルス幅変調器３５及びスペース(SPA
CE)パルス幅変調器３７へ線３３を経てそのブロックを１つずつ出力する。この
２つのパルス幅変調器はそれ等の夫々の入力端子へ印加された特定のコード・ブ
ロックに対応して個々独立に変化し得る持続時間を有する出力パルスを発生する
ように交互に動作する。ブロックは実質的に均一な割合で入力されるが、コード
・ブロックが含む特定の情報によって決定される可変的な割合で出力されるので
、バッファ３１はあらかじめ決められた数の４−ビット・コード・ブロックを貯
蔵するために充分な貯蔵容量を持たねばならない。【００１５】以下の表は１６個のとり得る４−ビット・コード・ブロックと、２つのパルス
幅変調器３５及び３７による対応するパルス出力の持続時間との間の１つの関係
を示す表である。【００１６】起こりうる可能なパルスの長さは最小の長さ1.0Ｌ及び最大の長さ2.5Ｌとの間
で均一なステップで変化する。すなわち、各マーク又は各スペースの長さは、所
定の再生許容周波数下限値を考慮して決定される最大長さ｛2.5Ｌ｝を２５等分
してなる各長さの全体｛0.1L，0.2L，…2.5L｝の中から、所定の再生許容周波数
上限値を越える周波数帯域に対応する各長さ｛0.1L，0.2L，…0.9L｝を除いた残
りの各長さ｛1.0L，1.1L，…2.5L｝の中から適宜に選択される。上述の再生許容
周波数が、レーザビームのスポット径に関連して決定されることについては、この種の光ディスクシステムの当業者であれば、容易に理解されるであろう。１
６個のコード・ブロックと、対応するパルスの持続時間との間の別の関係は「非
リニア・マーク長さの変調を有するビデオ再生器／記録器」と題するジャックエ
イチ．ベイリイ(Jack H.Bailey)の名前で出願された米国特許出願番号第974,183
号で与えられる。【００１７】図１の記録装置は更に、夫々MARK及びSPACE変調器３５及び３７から線４３及
び４５を経て受取られる連続したパルス幅変調パルスに従って、線４１を経て強
度変調器１７へ結合された変調信号を発生するための結合器３９を含む。結合器
はまた、一方の変調器からの以前の出力パルスが休止した直後に各変調器の動作
を開始するENABLE信号を夫々線４７及び４９を経て与えることによってMARK及び
SPACE変調器のタイミングを制御する。線４１上の結合器による変調信号出力はM
ARK変調器３５がパルスを出力する時はいつでも論理「１」状態にあり且つSPACE
変調器３７がパルスを出力する時はいつでも論理「０」状態にある。即ち連続し
た４−ビット・コード・ブロックを表わすマーク及びスペースの交互の所望のパ
ターンが記録体１１に形成される。【００１８】良好な実施例に於ては、記録体１１中の連続した記録トラックの各々は単一の
映像フレームのディジタル情報を記録する。第３図に示すように、各トラックは
Ｎ個のセクタを含み且つ各セクタは先頭部分、データ部分及び可変長の充填部分
を含む。一定数のデータが各データ部分に含まれるが各マーク及びスペースが可
変長なので、データ部分全体の長さは従って可変長である。従って充填部分は通
常は必要である。良好な実施例に於て、充填コードは記録された情報を再生する
ために補正装置に使うことの出来る特別な順序のマーク及びスペースから成って
いる。各セクタの先頭部分及び充填部分の両方はフォーマッタ２７（図１）によ
って発生され、フォーマッタ２７は、現在のフレーム番号及びセクタ番号のデー
タ表示と、記録されている現在のセクタ中の特定のロケーションのデータ表示を
貯蔵するためのレジスタを含む。【００１９】図３は同期コード、セクタ・アドレス・コード、データの性質（例えば映像、
音声等）を示す確認コード、正／補コード及び前のすべてのコードの伸長を許す
予備部分とを含む各セクタの先頭部分を示している。正／補コードは各セクタ中
のデータの長さを最小限にするための特別な手段として用いられる。既に説明し
たように、各セクタは一定量のデータを含むが記録されている特定のコード・ブ
ロックに従って可変長である。データの特定のセクタをレコードするのに必要と
するトラックの長さが予定された平均値を越えたことが若しフォーマッタ２７（
図１）によって決定されると、フォーマッタは記録の代わりに各コード・ブロッ
クの補数を出力し、且つ対応する先頭部分中の正／補コードを修飾する。このよ
うにして、任意のセクタ中にデータを貯蔵するのに必要とされる最大のトラック
の長さはすべて平均の長さ、即ちコード・ブロック0111又は1000に対応するマー
ク及びスペースの記録に対応する。【００２０】図３は又、各セクタのデータ部分のフォーマットを示している。データはＭ個
の連続する区分を含み、各区分は同期及び再開始のために特別なスーパーマーク
が先行していることが判る。良好な実施例では、各区分は映像フレームの切片か
ら取出される８×８のマトリックスに対応する。【００２１】図２は図１の記録された記録体１１のビデオ・ディスク・レプリカ５１を再生
演奏するための装置を示している。その装置は実質的に均一な強度を有する読取
り光ビーム５５を発生するための読取りレーザ５３を含む。このビームは、ディ
スクがスピンドル・モータ５７により均一な速度で回転された時放射方向に可動
なレンズ（図示せず）によってディスク５１上にビームスポットとして集束され
る。これはディスク上に記録されたマークのパターンに従って強度変調された反
射ビーム５９を生ずる。装置は次に変調されたビームを検出し、且つ対応する４
−ビット・コード・ブロックを決定するためにマーク及びスペースで変調された
連続するパルス幅の長さを測る。その後もとのベースバンド映像信号が再現される。【００２２】より具体的に言えば、図２の再生装置は反射ビーム５９の変調された強度を検
知するための検知器６１を含み且つ対応する電気信号を発生する。この信号は線
６３を経てMARKパルス幅復調器６５及びSPACEパルス幅復調器６７へ接続され、
それ等は連続するマーク及びスペースの長さを夫々測り、且つそれ等が表示する
特定のコード・ブロックを決定する。各復調器は、各マーク（又はスペース）の
検出された端により開始され且つ終止される線型ランプ（ramp）発生器と、対応
する４−ビット・コード・ブロックへランプのピーク値を変換するためのアナロ
グ／ディジダル変換器とを含ませることが出来る。この装置は更に夫々MARK及び
SPACE復調器６５及び６７から線７１及び７３上に供給される連続する４−ビッ
ト・コード・ブロックを挿入（interleave）するためのデコーダ６９を含む。【００２３】コード・ブロックの連続は線７５を経てデコーダ６９からバッファ及びデフォ
ーマッタ装置７７へ結合され、それは通常の技術を用いてデータを伸長(de-comp
ress)して、データを転換し実質的にもとのディジタル・フォーマットへ復帰す
る。加えて、デフォーマッタ装置７７は通常のディジタル化された垂直及び水平
同期信号を伸長されたビデオ・データ中に挿入する。次にデフォーマッタ装置７
７は線７９を経てＤ−Ａ（ディジタル／アナログ）コンバータ８１へ結合するた
めにリアル・タイムのディジタル・ビデオ信号を発生し、Ｄ−Ａコンバータは線
８３上に出力するためにもとのアナログ・ベースバンド映像信号を再生する。装
置７７から情報が実質的にリアル−タイム態様で出力されている間、コード・ブ
ロックが含む特定の情報によって決定される可変的な率でデコーダ６９から受取
られる連続した入力コード・ブロックのあらかじめ決められた部分を貯蔵するた
めめに、バッファ及びデフォーマッタ装置７７は充分に大きいメモリ容量を含ま
ねばならない。【００２４】上述の説明から本発明はディスク状記録体上のディジタル情報を記録し且つ再生するための改良されたシステムを提供することが判る。情報は、複数ビット・
コード・ブロックの連続に従って個々独立に可変長である、相次ぐマーク及び相
次ぐマーク間のスペースの両方の長さを以て、離隔したマークの連続の中に貯蔵
される。ディジタル情報はこれによって改良された記録効率で貯蔵される。【００２５】本発明は良好な実施例を参照して説明して来たが、本発明の精神を逸脱するこ
となく、映像信号に限らず音声信号にも施しうることが勿論である。【００２６】【発明の効果】以上の説明で明らかなように、本発明によれば、情報をマークのみを利用して
記録していた従来例に比べて記録効率を向上できることに加え、記録された交互
のマーク及びスペースの長さから直接的に元のコードブロックを誤りなく復号す
ることができる。また、各マーク及びスペースの長さには、予定される再生系を
考慮したラン・レングス・リミテッド規則が付与されているため、記録されたマ
ーク及びスペースを忠実に再生することができる。さらに、記録フォーマットに
も種々の工夫がなされているため、記録情報の識別等が容易となる。その結果、
本発明は、高い効率で記録された記録媒体からデジタル情報を容易に再生する方
法及び装置を提供するものである。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for reproducing digital information from a recording medium, and more particularly, to reproducing digital information in a pulse width modulation format. Optical video for
The present invention relates to a disk reproducing method and apparatus. 2. Description of the Related Art Video disk systems have become widely used for storing digital information with high recording efficiency. Information is typically recorded on a disk as a series of spaced marks arranged in a plurality of substantially circular and concentric recording tracks, such as a spiral pattern. One particularly effective system is a pulsed system in which each successively spaced mark on the disk represents a multi-bit code block and can be independently variable in length. Digital information has been recorded in a width modulation format. In such conventional systems, the space between successive marks, or the spacing between the beginnings of successive marks, is usually kept constant. That is, it will be understood that the length of the space could not be varied independently. [0003] Video discs can include a glass substrate with a thin metallic recording layer over the disc, and devices for recording digital information on the disc require that the disc be rotated at a uniform speed. Focus the writing light beam on the disc with the intensity of the light beam modulated according to the digital information to be recorded. When the light intensity exceeds a predetermined threshold, non-reflective pits or marks are formed in the recording layer, while
When the intensity does not exceed the threshold, the recording layer is not affected. Thus, the length of successively spaced marks corresponds to the duration during which the intensity of the focused beam exceeds this threshold. [0004] The recorded digital information is read from a replica of the recorded optical disc with a read light beam having a uniform intensity to generate a reflected beam having an intensity modulated by the recording pattern of the isolated marks. Reproduced by scanning. The intensity of the reflected beam is measured over the predetermined level to determine the length of the corresponding mark, and thus the particular binary code block that it represents. [0005] Although this conventional pulse width modulation technique has proven to be effective for recording digital information at relatively high recording efficiencies, it has been shown that digital efficiencies have been improved at higher efficiencies. A system for recording information is desired. SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and an apparatus which satisfy the above demand and can easily reproduce digital information recorded at high density. SUMMARY OF THE INVENTION The present invention is embodied in a system for recording and reproducing digital information on a recording medium. On this recording medium, information is recorded in a series of spaced apart marks which can vary independently. The length of each mark represents a discrete one of a contiguous multi-bit binary code block. In accordance with the present invention, the spacing or space between successive marks also has an independently variable length that represents a discrete block in a series of code blocks. Thereby, digital information is recorded on the recording medium with higher recording efficiency. More specifically, the present invention has particular application to video disc systems in which the video signal is recorded on a disc-shaped recording body of substantially circular and concentric continuous record tracks. ing. The recording device first functions to digitize the video signal and compress the digitized signal using known data compression techniques. The digitized signal is arranged in a sequence of code blocks of the same or mixed length, and a binary modulated signal is formed having state transitions determined according to successive code blocks. In the preferred embodiment, each code block contains four binary bits and the continuous state of the modulated signal is one.
It should have a 6-sided, independent duration. [0008] The modulated signal is coupled to a light intensity modulator, which alternates between intensities greater than and less than a predetermined threshold for an individual duration corresponding to a succession of multi-bit code blocks. Modulates the intensity of the write beam in a simple manner. The intensity-modulated beam is focused on the recording medium in a defined pattern to form corresponding microscopic pits or marks when the recording medium is rotated at a defined speed. The recording is then used to make a replica of the video disc using conventional techniques. The recorded digital information is reproduced from a disk replica by scanning successive tracks with a reading light beam having a substantially uniform intensity. this is,
The reflected (or transmitted) beam has an intensity modulated by the recording pattern, which is alternating marks and spaces. The playback device measures the duration of successive marks and spaces and determines the particular code block that each displays. After decompressing the sequence of detected code blocks, the original analog video signal can be reproduced. [0010] In a preferred embodiment, each successive recording track is used to record an individual video frame. However, since this particular pulse width modulation format results in a variable length mark and space recording pattern, the track length required to record each video frame is typically shorter than the entire track. . When this occurs, the remaining tracks are occupied by alternating fill and fill marks and spaces. FIG. 1 shows a recording apparatus for recording a digitized video signal on a disk-shaped record 11. The device comprises a writing laser 13 for generating a writing light beam 15 having a substantially uniform intensity, and an intensity modulator 17 for modulating the intensity of the beam according to a digitized modulation signal to be recorded.
Contains. The apparatus further includes a radially movable objective lens (not shown) for focusing the intensity-modulated beam onto the record, and rotating the record at a defined uniform speed (eg, 1800 rpm). And a spindle motor 19. Thus, the focused beam forms a substantially circular and concentric recording track in the recording medium. The recording medium 11 comprises a glass substrate with a metallic recording layer covering it, and the focused beam forms microscopic pits in the recording layer whenever its intensity exceeds a predetermined threshold. . The intensity is modulated alternately above and below this threshold according to the digital modulation signal to be recorded, so that a corresponding series of spaced pits or marks is formed in the record. In accordance with the present invention, a special pulse width modulation format is provided in which both successive marks and spaces between successive marks have independently variable lengths representing successive multi-bit binary code blocks. It is recorded on the recording body 11. As a result, digital information is recorded on the recording medium with improved recording efficiency. More specifically, the recording apparatus of FIG. 1 samples the baseband video signal on line 23 and converts the analog / digital signal to a corresponding digital signal.
The digital converter 21 is included. This digital signal is coupled via line 25 to a formatter 27 for removal of vertical and horizontal synchronization signals and compression of the digital information to format the compressed data into a continuous 4-bit code block. . These successive code blocks are passed on line 29 to the appropriate storage buffer 31.
The buffer 31 stores the mark (MARK) pulse width modulator 35 and the space (SPA).
CE) Output the blocks one by one to the pulse width modulator 37 via line 33. The two pulse width modulators operate alternately to generate output pulses having independently variable durations in response to particular code blocks applied to their respective input terminals. Since the blocks are input at a substantially uniform rate, but output at a variable rate determined by the specific information contained in the code block, buffer 31 stores a predetermined number of 4-bit codes. -It must have sufficient storage capacity to store blocks. The following table shows one relationship between the 16 possible 4-bit code blocks and the duration of the corresponding pulse output by the two pulse width modulators 35 and 37. . [0016] The possible pulse lengths vary in uniform steps between a minimum length of 1.0 L and a maximum length of 2.5 L. In other words, the length of each mark or each space is the total length {0.1L, 0.2 L,... 2.5L}, each length {1.0L, excluding each length {0.1L, 0.2L,... It is appropriately selected from 1.1L, ... 2.5L｝. It will be easily understood by those skilled in the art of this type of optical disc system that the above-mentioned allowable reproduction frequency is determined in relation to the spot diameter of the laser beam. 1
Another relationship between the six code blocks and the duration of the corresponding pulse is Jack H. J., entitled "Video Player / Recorder with Nonlinear Mark Length Modulation". U.S. Patent Application No. 974,183, filed under the name of Jack H. Bailey
Given in the issue. The recording device of FIG. 1 further includes a modulation coupled to intensity modulator 17 via line 41 according to successive pulse width modulation pulses received via lines 43 and 45 from MARK and SPACE modulators 35 and 37, respectively. It includes a combiner 39 for generating a signal. The combiner also provides MARK and LINE signals by providing an ENABLE signal via lines 47 and 49, respectively, to initiate operation of each modulator immediately after the previous output pulse from one modulator has paused.
Controls the timing of the SPACE modulator. The modulated signal output by the combiner on line 41 is M
Whenever the ARK modulator 35 outputs a pulse, it is in the logic "1" state and
Whenever modulator 37 outputs a pulse, it is in a logic "0" state. That is, an alternating desired pattern of marks and spaces representing successive 4-bit code blocks is formed on the recording medium 11. In the preferred embodiment, each successive recording track in recording 11 records digital information for a single video frame. As shown in FIG. 3, each track includes N sectors and each sector includes a head portion, a data portion, and a variable length filling portion. Since a fixed number of data is included in each data portion but each mark and space is of variable length, the overall length of the data portion is therefore of variable length. Thus, a filling portion is usually required. In the preferred embodiment, the fill code comprises a special sequence of marks and spaces that can be used by the corrector to reproduce the recorded information. Both the start and fill portions of each sector are generated by the formatter 27 (FIG. 1), which provides a data representation of the current frame number and sector number and the location of the particular location in the current sector being recorded. Includes a register for storing the data indication. FIG. 3 shows synchronization codes, sector address codes, and data properties (eg, video,
2 shows a head portion of each sector including a confirmation code indicating voice and the like, a correct / complementary code, and a spare portion allowing expansion of all preceding codes. Positive / complementary codes are used as a special measure to minimize the length of the data in each sector. As already explained, each sector contains a certain amount of data but is of variable length according to the particular code block being recorded. If the length of the track required to record a particular sector of data exceeds a predetermined average, the formatter 27 (
As determined by FIG. 1), the formatter outputs the complement of each code block instead of the record, and modifies the positive / complement code in the corresponding head part. In this way, the maximum track length needed to store data in any sector will all correspond to the average length, i.e. the mark and space record corresponding to code block 0111 or 1000. I do. FIG. 3 also shows the format of the data portion of each sector. It can be seen that the data includes M consecutive sections, each section preceded by a special supermark for synchronization and restart. In the preferred embodiment, each section corresponds to an 8 × 8 matrix extracted from a section of a video frame. FIG. 2 shows an apparatus for reproducing and playing the video disk replica 51 of the recorded body 11 of FIG. The apparatus includes a reading laser 53 for generating a reading light beam 55 having a substantially uniform intensity. The beam is focused as a beam spot on the disk 51 by a radially movable lens (not shown) when the disk is rotated at a uniform speed by the spindle motor 57. This results in a reflected beam 59 that is intensity modulated according to the pattern of the marks recorded on the disk. The device then detects the modulated beam and
-Measure the length of consecutive pulse widths modulated with marks and spaces to determine a bit code block. Thereafter, the original baseband video signal is reproduced. More specifically, the reproducing apparatus of FIG. 2 includes a detector 61 for detecting the modulated intensity of the reflected beam 59 and generates a corresponding electric signal. This signal is connected via line 63 to a MARK pulse width demodulator 65 and a SPACE pulse width demodulator 67,
They measure the length of successive marks and spaces, respectively, and determine the particular code block they represent. Each demodulator is a linear ramp generator, started and terminated by the detected end of each mark (or space), and for converting the peak value of the ramp into a corresponding 4-bit code block. Analog-to-digital converter. This device is further equipped with MARK and
Includes a decoder 69 for interleaving successive 4-bit code blocks provided on lines 71 and 73 from SPACE demodulators 65 and 67. The sequence of code blocks is coupled via line 75 from decoder 69 to a buffer and deformatter unit 77, which decompresses the data using conventional techniques.
ress) to convert the data and substantially return to the original digital format. In addition, the deformatter unit 77 inserts normal digitized vertical and horizontal sync signals into the decompressed video data. Next, the deformatter device 7
7 generates a real time digital video signal for coupling to a DA (Digital / Analog) converter 81 via line 79, the DA converter providing the original analog signal for output on line 83.・ Reproduce the baseband video signal. While the information is output from device 77 in a substantially real-time manner, a predetermined sequence of successive input code blocks received from decoder 69 at a variable rate determined by the particular information contained in the code blocks. In order to store the allocated portion, the buffer and deformatter unit 77 must include a sufficiently large memory capacity. From the above description, it can be seen that the present invention provides an improved system for recording and reproducing digital information on a disk-like recording. The information consists of multiple bits
It is stored in a series of spaced marks with both the length of the successive marks and the space between the successive marks, which are independently variable in length according to the sequence of code blocks. Digital information is thereby stored with improved recording efficiency. Although the present invention has been described with reference to preferred embodiments, it will be appreciated that the invention can be applied to audio signals as well as video signals without departing from the spirit of the invention. As is apparent from the above description, according to the present invention, in addition to being able to improve the recording efficiency as compared with the conventional example in which information is recorded using only marks, the information is recorded. The original code block can be decoded without error directly from the length of the alternate marks and spaces. In addition, since the length of each mark and space is given a run length limited rule in consideration of an expected reproduction system, the recorded mark and space can be reproduced faithfully. Further, since various modifications are made to the recording format, identification of recording information and the like becomes easy. as a result,
The present invention provides a method and apparatus for easily reproducing digital information from a recording medium recorded with high efficiency.

【図面の簡単な説明】【図１】本発明に従った特別なパルス幅変調形式で、ビデオ・ディスク上にディジタル
化された映像信号を記録するための読取り装置のブロック図である。【図２】本発明に従って特別なパルス幅変調形式でビデオ・ディスク上に貯蔵されたデ
ィジタル化された映像信号を再生するための再生装置のブロック図である。【図３】ビデオ・ディスク上のデータのフォーマットを説明する概要図である。【図４】記録されている複数の起きうる４−ビット・コード・ブロックの各々に対応す
る連続したマーク（及びスペース）のための規定の長さを示す図表である。【符号の説明】１１…ディスク状レコード、１３…書き込みレーザ、１５…書込み光ビーム、１７…強度変調器、１９…スピンドル・モータ、２１…アナログ／デジタル変換器２７…フォーマッタ３１…バッファ、３７…パルス幅変調器、３９…結合器。BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a reader for recording a digitized video signal on a video disk in a special pulse width modulation format according to the present invention. FIG. 2 is a block diagram of a reproducing apparatus for reproducing a digitized video signal stored on a video disk in a special pulse width modulation format according to the present invention. FIG. 3 is a schematic diagram illustrating a format of data on a video disk. FIG. 4 is a chart showing the prescribed length for consecutive marks (and spaces) corresponding to each of a plurality of possible 4-bit code blocks being recorded. [Description of Signs] 11: disk-shaped record, 13: writing laser, 15: writing light beam, 17: intensity modulator, 19 ... spindle motor, 21 ... analog / digital converter 27 ... formatter 31 ... buffer, 37 ... Pulse width modulator, 39 ... combiner.

Claims

Claims 1. A method for restoring digital information stored on a recording medium, wherein the digital information is stored as a series of marks and spaces, and wherein the digital information is stored as a series of marks and spaces. The space has an independently variable length representing a plurality of coded binary bits, the method comprising: scanning the recording medium and changing a reproduced signal according to a storage pattern of the mark and the space. A first step of detecting the length of the consecutive marks and spaces in response to the playback signal and generating an output signal representative of the corresponding particular coded signal sequence. and second step, after storing temporarily at varying information rate according to the recording information the output signal to the buffer sequentially from the buffer information at a constant speed Information restoring method of the third step of outputting, characterized in that it contains. 2. A method for restoring digital information stored on a recording medium, the method comprising scanning a recording medium containing digital information, the digital information comprising:
Obtained by converting a sequence of original binary bits, which is digital information to be recorded, into a sequence of coded signals, wherein the conversion encodes each original portion of the sequence of binary bits. The binary encoding using only a first encoding operation to encode the part and without using any operation of processing the encoded part subsequent to the first encoding operation. By coding each part of the sequence of bits, each said coded part being the final code representing each original part of the series of binary bits, and of the coded signal Information representing continuity is recorded on the recording medium as a continuation of the corresponding alternating mark and space, and the length of the continuous mark and space , Between a minimum length and a maximum length which is more than twice that of the coded signal, is modulated to an independent length according to the continuation of the coded signal, thereby changing the storage pattern of marks and spaces and thus the reproduced signal. A second step of responding to the playback signal to detect the length of the consecutive marks and spaces, which generates an output signal representing a corresponding coded particular series. Wherein the track is divided into unit sections for recording a specified amount of digital information,
An information restoration method, characterized in that when the entire unit section is not required for recording, the remaining part of the unit section is occupied by prescribed alternating marks and spaces. 3. A method for restoring digital information stored on a recording medium, the method comprising scanning a recording medium containing digital information, the digital information comprising:
Obtained by converting a sequence of original binary bits, which is digital information to be recorded, into a sequence of coded signals, wherein the conversion encodes each original portion of the sequence of binary bits. The binary encoding using only a first encoding operation to encode the part and without using any operation of processing the encoded part subsequent to the first encoding operation. By coding each part of the sequence of bits, each said coded part being the final code representing each original part of the series of binary bits, and of the coded signal The information representing the continuation is preceded as an alternating continuation of the mark and space so that the mark and space indicate the corresponding part of the coded signal. The length of the consecutive marks and spaces recorded on the recording medium is modulated to an independent length according to the continuation of the coded signal, between a minimum length and a maximum length that is twice or more the minimum length. A first step of generating a reproduction signal that varies according to the storage pattern of marks and spaces, and responsive to the reproduction signal to detect the length of the consecutive marks and spaces, Second means for generating an output signal representative of a particular coded sequence of sequences, wherein the track is divided into unit intervals for recording a defined amount of digital information;
An information restoration method, characterized in that an identification record for identifying a type of information recorded in the unit section is recorded at a specific position of the unit section. 4. The information restoration method according to claim 3, wherein the identification code can represent at least video information and audio information. 5. A method for restoring digital information stored on a recording medium, the method comprising scanning a recording medium containing digital information, the digital information comprising:
Obtained by converting a sequence of original binary bits, which is digital information to be recorded, into a sequence of coded signals, wherein the conversion encodes each original portion of the sequence of binary bits. The binary encoding using only a first encoding operation to encode the part and without using any operation of processing the encoded part subsequent to the first encoding operation. By coding each part of the sequence of bits, each said coded part being the final code representing each original part of the series of binary bits, and of the coded signal Information representing continuity is recorded on the recording medium as a continuation of the corresponding alternating mark and space, and the length of the continuous mark and space , Between a minimum length and a maximum length which is more than twice that of the coded signal, is modulated to an independent length according to the continuation of the coded signal, thereby changing the storage pattern of marks and spaces and thus the reproduced signal. A second step of responding to the playback signal to detect the length of the consecutive marks and spaces, which generates an output signal representing a corresponding coded particular series. Wherein the track is divided into unit sections for recording a specified amount of digital information,
An information restoring method, wherein an address code for specifying the unit section is recorded at a specific position of the unit section. 6. A method for restoring digital information stored on a recording medium, the method comprising scanning a recording medium containing digital information, the digital information comprising:
It is obtained by converting a sequence of original binary bits, which is digital information to be recorded, into a sequence of coded signals, each of said sequence of binary bits being the only possible sequence of coded signals. And the information representing the continuation of the coded signal is recorded on the recording medium as a corresponding series of alternating marks and spaces, and the length of the continuous marks and spaces is recorded. The length is modulated to an independent length according to the continuation of the coded signal, between a minimum length and a maximum length that is more than twice as long, thereby varying according to the storage pattern of marks and spaces. A first step of generating a playback signal; responsive to the playback signal to detect a length of the consecutive marks and spaces, Generating an output signal representative of a particular sequence of coded signals, wherein said track is divided into unit intervals for recording a defined amount of digital information;
An information restoration method, characterized in that when the entire unit section is not required for recording, the remaining part of the unit section is occupied by prescribed alternating marks and spaces. 7. A method for restoring digital information stored on a recording medium, the method comprising scanning a recording medium containing digital information, the digital information comprising:
It is obtained by converting a sequence of original binary bits, which is digital information to be recorded, into a sequence of coded signals, each of said sequence of binary bits being the only possible sequence of coded signals. And the information representing the continuation of the coded signal may be represented as a series of alternating marks and spaces, such that the marks and spaces indicate the corresponding portions of the coded signal. The length of the consecutive marks and spaces recorded on the recording medium is set to an independent length according to the continuation of the encoded signal, between a minimum length and a maximum length that is twice or more the minimum length. A first step of generating a reproduced signal that is modulated according to the storage pattern of the marks and spaces, thereby changing the continuous mark and space. Second means responsive to the playback signal to detect the length of the source and generating an output signal representative of a corresponding encoded particular sequence. Divided into unit sections for recording digital information,
An information restoring method, characterized in that an identification code for identifying a type of information recorded in the unit section is recorded at a specific position of the unit section. 8. The information restoration method according to claim 7, wherein said identification code can represent at least video information and audio information. 9. A method for restoring digital information stored on a recording medium, the method comprising scanning a recording medium containing digital information, the digital information comprising:
It is obtained by converting a sequence of original binary bits, which is digital information to be recorded, into a sequence of coded signals, each of said sequence of binary bits being the only possible sequence of coded signals. And the information representing the continuation of the coded signal is recorded on the recording medium as a corresponding series of alternating marks and spaces, and the length of the continuous marks and spaces is recorded. The length is modulated to an independent length according to the continuation of the coded signal, between a minimum length and a maximum length that is more than twice as long, thereby varying according to the storage pattern of marks and spaces. A first step of generating a playback signal; responsive to the playback signal to detect a length of the consecutive marks and spaces, Second means for generating an output signal representative of a particular coded sequence of sequences, wherein the track is divided into unit intervals for recording a defined amount of digital information;
An information restoring method, wherein an address code for specifying the unit section is recorded at a specific position of the unit section. 10. An apparatus for restoring digital information stored on a recording medium, wherein said digital information is stored as a series of marks and spaces, and said continuous marks and spaces are composed of a plurality of bits. Having an independently variable length representing the encoded binary bits of the first and second bits, wherein the apparatus scans the recording medium to generate a reproduced signal that varies according to the storage pattern of the marks and spaces. Means for detecting the length of the consecutive marks and spaces in response to the playback signal, and generating an output signal representative of the sequence of the corresponding particular coded signal; after storing temporarily at varying information rate according to the recording information the output signal to the buffer, and the third means for outputting sequentially from the buffer information at a constant speed, but Information restoring device, characterized in that are rare. 11. An apparatus for restoring digital information stored on a recording medium, wherein the apparatus scans a recording medium containing digital information, wherein the digital information comprises:
Obtained by converting a sequence of original binary bits, which is digital information to be recorded, into a sequence of coded signals, wherein the conversion encodes each original portion of the sequence of binary bits. The binary encoding using only a first encoding operation to encode the part and without using any operation of processing the encoded part subsequent to the first encoding operation. By coding each part of the sequence of bits, each said coded part being the final code representing each original part of the series of binary bits, and of the coded signal Information representing continuity is recorded on the recording medium as a continuation of the corresponding alternating mark and space, and the length of the continuous mark and space , Between a minimum length and a maximum length which is more than twice that of the coded signal, is modulated to an independent length according to the continuation of the coded signal, thereby changing the storage pattern of marks and spaces and thus the reproduced signal. And a second means responsive to the playback signal to detect the length of the consecutive marks and spaces, which generates an output signal representing a corresponding encoded particular sequence. The track is divided into unit sections for recording a specified amount of digital information,
The information restoration apparatus according to claim 1, wherein when the entire unit section is not required for recording, the remaining part of the unit section is occupied by prescribed alternating marks and spaces. 12. An apparatus for restoring digital information stored on a recording medium, wherein the apparatus scans a recording medium containing digital information, the digital information comprising:
Obtained by converting a sequence of original binary bits, which is digital information to be recorded, into a sequence of coded signals, wherein the conversion encodes each original portion of the sequence of binary bits. The binary encoding using only a first encoding operation to encode the part and without using any operation of processing the encoded part subsequent to the first encoding operation. By coding each part of the sequence of bits, each said coded part being the final code representing each original part of the series of binary bits, and of the coded signal The information representing the continuation is preceded as an alternating continuation of the mark and space so that the mark and space indicate the corresponding part of the coded signal. The length of the consecutive marks and spaces recorded on the recording medium is modulated to an independent length according to the continuation of the coded signal, between a minimum length and a maximum length that is twice or more the minimum length. First means for generating a reproduction signal that varies according to the storage pattern of marks and spaces, and responsive to the reproduction signal to detect the length of the consecutive marks and spaces, which responds Second means for generating an output signal representative of a particular coded sequence of sequences, wherein the track is divided into unit intervals for recording a defined amount of digital information;
An information restoring apparatus, characterized in that an identification code for identifying a type of information recorded in the unit section is recorded at a specific position of the unit section. 13. The information restoration apparatus according to claim 12, wherein the identification code can represent at least video information and audio information. 14. An apparatus for restoring digital information stored on a recording medium, said apparatus scanning a recording medium containing digital information, said digital information comprising:
Obtained by converting a sequence of original binary bits, which is digital information to be recorded, into a sequence of coded signals, wherein the conversion encodes each original portion of the sequence of binary bits. The binary encoding using only a first encoding operation to encode the part and without using any operation of processing the encoded part subsequent to the first encoding operation. By coding each part of the sequence of bits, each said coded part being the final code representing each original part of the series of binary bits, and of the coded signal Information representing continuity is recorded on the recording medium as a continuation of the corresponding alternating mark and space, and the length of the continuous mark and space , Between a minimum length and a maximum length which is more than twice that of the coded signal, is modulated to an independent length according to the continuation of the coded signal, thereby changing the storage pattern of marks and spaces and thus the reproduced signal. And a second means responsive to the playback signal to detect the length of the consecutive marks and spaces, which generates an output signal representing a corresponding encoded particular sequence. The track is divided into unit sections for recording a specified amount of digital information,
An information restoration device, wherein an address code for specifying the unit section is recorded at a specific position of the unit section. 15. An apparatus for restoring digital information stored on a recording medium, said apparatus scanning a recording medium containing digital information, wherein said digital information comprises:
It is obtained by converting a sequence of original binary bits, which is digital information to be recorded, into a sequence of coded signals, each of said sequence of binary bits being the only possible sequence of coded signals. And the information representing the continuation of the coded signal is recorded on the recording medium as a corresponding series of alternating marks and spaces, and the length of the continuous marks and spaces is recorded. The length is modulated to an independent length according to the continuation of the coded signal, between a minimum length and a maximum length that is more than twice as long, thereby varying according to the storage pattern of marks and spaces. First means for generating a playback signal; responsive to the playback signal to detect a length of the consecutive marks and spaces, which Second means for generating an output signal representing a particular coded sequence, wherein said track is divided into unit intervals for recording a defined amount of digital information,
The information restoration apparatus according to claim 1, wherein when the entire unit section is not required for recording, the remaining part of the unit section is occupied by prescribed alternating marks and spaces. 16. An apparatus for restoring digital information stored on a recording medium, wherein the apparatus scans a recording medium containing digital information, wherein the digital information comprises:
It is obtained by converting a sequence of original binary bits, which is digital information to be recorded, into a sequence of coded signals, each of said sequence of binary bits being the only possible sequence of coded signals. And the information representing the continuation of the coded signal may be represented as a series of alternating marks and spaces, such that the marks and spaces indicate the corresponding portions of the coded signal. The length of the continuous mark and space recorded on the recording medium is set to an independent length according to the continuation of the coded signal, between a minimum length and a maximum length that is twice or more the minimum length. First means for generating a reproduced signal which is modulated and thereby varies according to the storage pattern of the marks and spaces; Second means responsive to the playback signal to detect the length of the signal and generating an output signal representative of a corresponding encoded particular sequence. Is divided into unit sections for recording
An information restoring apparatus, characterized in that an identification code for identifying a type of information recorded in the unit section is recorded at a specific position of the unit section. 17. The information restoration apparatus according to claim 16, wherein said identification code can represent at least video information and audio information. 18. An apparatus for restoring digital information stored on a recording medium, wherein the apparatus scans a recording medium containing digital information, wherein the digital information comprises:
It is obtained by converting a sequence of original binary bits, which is the digital information to be recorded, into a sequence of coded signals, each of said sequence of binary bits being the only possible sequence of coded signals. And the information representing the continuation of the coded signal is recorded on the recording medium as a corresponding series of alternating marks and spaces, and the length of the continuous marks and spaces is recorded. The length is modulated to an independent length according to the continuation of the coded signal, between a minimum length and a maximum length which is more than twice as long, thereby varying according to the storage pattern of marks and spaces. First means for generating a playback signal; responsive to the playback signal to detect a length of the consecutive marks and spaces, which Second means for generating an output signal representing a particular coded sequence, wherein said track is divided into unit intervals for recording a defined amount of digital information,
An information restoration device, wherein an address code for specifying the unit section is recorded at a specific position of the unit section.