JPS61271628A - Recording and reproducing method for optical disk - Google Patents

Abstract

PURPOSE:To add a writing function by providing the second recording pit string on a recording medium with a laser beam modulated by the frequency different from the signal frequency of the pit string on an optical disk and separating the signals from the reflected laser beam from each pit string. CONSTITUTION:An optical recording medium layer 3 of a Te alloy is formed in thickness ranging from several tens to several hundreds Angstrom on a transparent resinous disk and a pit string 31 modulated with a frequency sufficiently higher (or lower) than the signal frequency of the existing bit 11. The positions of the string 31 and the string 11 can be vertically overlapped. A laser beam is irradiated in reproducing on both strings, the reflected beam is transduced into an electric signal and the signals of respective components are separated by a specified filter circuit. Tracking servo in recording and reproduction is carried out by a well-known method with the existing binary digit string 11 as a reference. By this constitution, a crosstalk between two kinds of information is eliminated, the pitch between the existing pit strings need not be expanded, optical head tracking can be done by completely the same method and the constitution is not complicated.

Description

【発明の詳細な説明】 産業上の利用分野 この発明は、通常再生専用として作られている光ディス
クの構造に改良を加えることにより書き込み機能も追加
できるようにしたもので、特にその記録再生方法に係る
。[Detailed Description of the Invention] Industrial Field of Application This invention is an optical disc that is made for normal playback only, by improving its structure so that a writing function can be added to it. Related.

従来の技術 現在、再生専用の光ディスクとしてオーディオ情報が記
録された所謂コンパクトディスクｃｃＤ）が市販されて
いる。このコンパクトディスクの利用方法として画像情
報も入れたり、また各種デジタルデータを入れたパーソ
ナルコンピュータの外部メモリ（ＣＤ−ＲＯＭ）が検討
されている。特に、再生専用メモリとしては非接触型で
あり、かつ大容量であることからその実用化が注目され
ている。2. Description of the Related Art Currently, so-called compact discs (ccD) on which audio information is recorded are commercially available as read-only optical discs. As a method of using this compact disk, it is being considered that image information may be stored therein, and an external memory (CD-ROM) for a personal computer may be used to store various digital data. In particular, since it is a non-contact type read-only memory and has a large capacity, its practical use is attracting attention.

この種のコンパクトディスクは周知のように第２図に示
される構造を持つが、それらはいずれもマスター、マザ
ー、スタンパの順に型を起こし、スタンパを金型として
ポリカーボネート、エポキシあるいはアクリル樹脂（Ｐ
ＭＭＡ：ボリメテルーメタクリレート）等の透明樹脂を
用いて射出成形することによって基板が作られる。As is well known, this type of compact disc has the structure shown in Figure 2, but in all of them, a mold is formed in the order of master, mother, and stamper, and the stamper is used as the mold to make polycarbonate, epoxy, or acrylic resin (P).
The substrate is made by injection molding using a transparent resin such as MMA (bolimethacrylate).

第２図において、１けポリカーボネートのような透明樹
脂からなる射出成形基板で、１１はオーディオあるいは
データ等の所定の情報を表わす既成ビットである。ビッ
ト１１は通常のオーディオレコード盤の溝のようにうず
巻状に連らなって列を形成している。ピッ）１１が形成
された面の外側にはアルミニウムの反射膜２が形成され
ており、読み出す時のレーザ光は矢印Ａのように反対側
の面１３から透過照射される。反射光の方向はビット１
１の有無によって変化するが、その反射光のうち直線的
に戻った成分の強度を読み取って電気信号に変換し所定
の情報が再生されるようになっている。In FIG. 2, 1 is an injection molded substrate made of transparent resin such as polycarbonate, and 11 is a ready-made bit representing predetermined information such as audio or data. The bits 11 are arranged in a spiral pattern like the grooves on a normal audio record. An aluminum reflective film 2 is formed on the outside of the surface on which the pixel 11 is formed, and a laser beam during reading is transmitted through and irradiated from the opposite surface 13 as indicated by arrow A. The direction of the reflected light is bit 1
1, the intensity of the linearly returned component of the reflected light is read and converted into an electrical signal to reproduce predetermined information.

発明が解決しようとする問題点 上述のように従来のコンパクトディスクのような予めビ
ット列が射出成形されたものは、再生専用としてしか利
用できなかった。今後、例えばパーソナルコンピュータ
の外部メモリとして利用される場合、ＲＯＭとして用い
られるだけでなく追記や書替え可能な機能も備えること
ができるとしたら、その用途は一段と拡大されよう。Problems to be Solved by the Invention As mentioned above, conventional compact discs in which bit strings are injection molded in advance can only be used for playback purposes. In the future, for example, when used as an external memory for a personal computer, its uses will be further expanded if it can not only be used as a ROM but also have additional write and rewritable functions.

問題を解決するための手段゛ この発明の方法は、透明樹脂を射出成形することにより
所定の情報を表わすビット列を一方の面に予め形成し、
その面に反射膜の代りに光記録媒体層を形成してなる光
ディスクに適用されるものである。すなわち、この発明
は前述の既成ビット列の示す信号周波数と異なる周波数
の信号で変調されたレーザ光により記録媒体層上に任意
の情報を表わす第２の記録ビット列を形成し、各ビット
列にレーザ光を照射してその反射光を読み取り、各周波
数の信号をそれぞれ分離して各情報を再生するようにし
たものでおる。Means for Solving the Problem: The method of the present invention involves forming a bit string representing predetermined information on one side in advance by injection molding a transparent resin;
This is applied to an optical disk in which an optical recording medium layer is formed instead of a reflective film on the surface. That is, the present invention forms a second recording bit string representing arbitrary information on a recording medium layer using a laser beam modulated with a signal having a frequency different from that indicated by the already-formed bit string, and applies the laser beam to each bit string. It is designed to emit light, read the reflected light, separate the signals of each frequency, and reproduce each piece of information.

作用 この発明によれば、予め設けられているビット列の表わ
す信号周波数と異なる周波数を持つ信号によって変調さ
れたレーザ光により後記録ビット列を形成しているので
、相互の周波数倍率が十分大きければ読み取シ再生時に
フィルタ回路等を用いて容易に分離できる。したがって
、既成ビット列に重ねて第２のビット列を形成しても信
号分離ができ、両ビット列の記録密度に影響を与えるこ
ともないので都合が良い。また、光記録ヘッドとしては
、既成ビット列の再生用のものを後記録ビット列の記録
再生に使用することができ、構造上も簡単でコスト的に
も有利となる。According to this invention, since the post-recording bit string is formed by a laser beam modulated by a signal having a frequency different from the signal frequency represented by the pre-provided bit string, if the mutual frequency multiplier is sufficiently large, the reading signal can be read out. It can be easily separated using a filter circuit or the like during reproduction. Therefore, even if the second bit string is formed overlapping the existing bit string, signal separation is possible and the recording density of both bit strings is not affected, which is convenient. Moreover, as an optical recording head, one for reproducing a pre-existing bit string can be used for recording and reproducing a post-recorded bit string, which is simple in structure and advantageous in terms of cost.

実施例 この発明の実施例を第１図を参照にして説明する。３け
、第２図に示すアルミニウム反射膜２０代りに形成され
た光記録媒体層で、例えばテルル系合金を材質とする層
厚およそ数十〜数百λを持つものである。３１は、この
光記録媒体層３上にレーザ光を当てて形成された後記録
ビットである。Embodiment An embodiment of the present invention will be described with reference to FIG. Third, the optical recording medium layer is formed in place of the aluminum reflective film 20 shown in FIG. 2, and is made of, for example, a tellurium-based alloy and has a layer thickness of approximately several tens to several hundreds λ. 31 is a post-recording bit formed on this optical recording medium layer 3 by applying a laser beam.

このビット３１の列は、射出成形により作られている既
成ピッ１−１１の列が表わす信号周波数と異なる周波数
を持つ信号を表わす。すなわち、レーザ光は記録時ビッ
ト３１を作るために既成ビット１１の信号周波数に対し
て例えば３〔倍の高い（または十分低い）周波数を持つ
信号によって変調されることになる。そして、後記録ビ
ット３１０列は、既成ビット１１の列と分離した領域に
形成しなくても良く、第１図に示すように上下重複した
位置に設けられても良い。This row of bits 31 represents a signal having a different frequency from the signal frequency represented by the row of ready-made pins 1-11 made by injection molding. That is, the laser beam is modulated by a signal having a frequency that is, for example, three times higher (or sufficiently lower) than the signal frequency of the existing bit 11 in order to create the bit 31 during recording. The post-recorded bit 310 column does not have to be formed in a separate area from the pre-recorded bit 11 column, but may be provided in a position that overlaps the column above and below, as shown in FIG.

再生時には、いずれのビット列もレーザ光が照射され、
その反射光を電気信号に変換して読み取るわけであるが
、各ビット列の持つ周波数成分だけを通過させる周知の
構成のフィルタ回路に工って各成分の信号を分離すれば
よい。During playback, each bit string is irradiated with laser light,
The reflected light is converted into an electrical signal and read, and the signals of each component can be separated by using a filter circuit with a well-known configuration that passes only the frequency components of each bit string.

なお、記録時および再生時におけるトラッキングサーボ
は、既成ピッ）１１の列を基準にして周知の方法で行え
ばよい。Note that tracking servo during recording and playback may be performed using a well-known method using the already-formed 11 rows as a reference.

上記実施例においては後記録ビット３１を既成ビット１
１の列と重複させて形成しているが、ビット列間の領域
１４にかかるように形成しても同様に行える。In the above embodiment, the post-recorded bit 31 is set to the pre-recorded bit 1.
Although it is formed so as to overlap the column 1, the same effect can be achieved by forming it so as to overlap the area 14 between the bit strings.

また、後記録ビット３１の形状としては、凹凸、ふくら
み、記録媒体層の有無、屈折または反射率の変化等いろ
いろ考えられるが、読み出し光で検出できる光学的変化
であれば適用できる。Further, various shapes of the post-recorded bit 31 can be considered, such as unevenness, bulge, presence or absence of a recording medium layer, change in refraction or reflectance, etc., but any optical change that can be detected by reading light can be applied.

発明の詳細 な説明してきたように、この発明の方法によれば、既成
ビット列と後記録ビット列が表わすそれぞれの信号周波
数を、再生時に電気回路により分離可能な関係の値に選
んでいる。したがって、２種類の再生情報間にクロスト
ークが無く、既成ビット列のピッチは従来のままでよく
、敢えて変更しなくても済む。両ビット列を同一領域に
全く重複して形成することが許されるので、光ヘッドの
トラッキングも全く同じ方法でやることができ構成を複
雑にする必要がなく都合が良い。As described in detail, according to the method of the present invention, the respective signal frequencies represented by the pre-recorded bit string and the post-recorded bit string are selected to have such a relationship that they can be separated by an electric circuit during reproduction. Therefore, there is no crosstalk between the two types of reproduced information, and the pitch of the existing bit string can remain the same as before, and there is no need to change it. Since both bit strings are allowed to be formed completely overlappingly in the same area, tracking of the optical head can also be performed in exactly the same way, which is convenient because there is no need to complicate the configuration.

また、再生回路を各周波数単位に２系統設けておけば２
種類の異なる情報を同時に取シ出すことができ、その用
途も拡大できる。Also, if two regeneration circuits are provided for each frequency unit, two
Different types of information can be retrieved at the same time, and its uses can be expanded.

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

第１図はこの発明を適用した光ディスクの構造を示す一
部切欠斜視図、第２図は従来の光ディスクの構造を示す
一部切欠斜視図である。 １・・・・・・射出成形基板、 ２・・・・・・アルミニウム反射板、 ３・・・・・・光記録媒体層、 １１・・・既成ビット、 ３１・・・後記録ビット。FIG. 1 is a partially cutaway perspective view showing the structure of an optical disk to which the present invention is applied, and FIG. 2 is a partially cutaway perspective view showing the structure of a conventional optical disk. DESCRIPTION OF SYMBOLS 1...Injection molded substrate, 2...Aluminum reflecting plate, 3...Optical recording medium layer, 11...Pre-made bit, 31...Post-recording bit.

Claims (1)

【特許請求の範囲】[Claims] 透明樹脂を射出成形することにより所定の情報を表わす
ビット列を一方の面に予め形成し、前記面に反射膜の代
りに光記録媒体層を形成してなる光ディスクを用い、前
記ビット列の示す信号周波数と異なる周波数の信号で変
調されたレーザ光により前記記録媒体層上に任意情報を
表わす第２の記録ビット列を形成し、前記各ビット列に
レーザ光を照射してその反射光を読み取り、前記各周波
数の信号をそれぞれ分離して各情報を再生することを特
徴とする光ディスクの記録再生方法。Using an optical disk, in which a bit string representing predetermined information is formed in advance on one surface by injection molding of transparent resin, and an optical recording medium layer is formed on the surface instead of a reflective film, the signal frequency indicated by the bit string is A second recording bit string representing arbitrary information is formed on the recording medium layer by a laser beam modulated with a signal of a frequency different from that, and each bit string is irradiated with a laser beam and the reflected light is read. A method for recording and reproducing an optical disc, characterized in that each signal is separated and each piece of information is reproduced.