JPH04123321A - Optical recording and reproducing device - Google Patents
Optical recording and reproducing deviceInfo
- Publication number
- JPH04123321A JPH04123321A JP24323790A JP24323790A JPH04123321A JP H04123321 A JPH04123321 A JP H04123321A JP 24323790 A JP24323790 A JP 24323790A JP 24323790 A JP24323790 A JP 24323790A JP H04123321 A JPH04123321 A JP H04123321A
- Authority
- JP
- Japan
- Prior art keywords
- focus
- agc
- signal
- circuit
- error 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.)
- Granted
Links
- 230000003287 optical effect Effects 0.000 title claims description 12
- 230000003321 amplification Effects 0.000 claims abstract description 11
- 238000003199 nucleic acid amplification method Methods 0.000 claims abstract description 11
- 239000006059 cover glass Substances 0.000 abstract description 14
- 238000010586 diagram Methods 0.000 description 4
- 238000000034 method Methods 0.000 description 3
- 238000001514 detection method Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000001678 irradiating effect Effects 0.000 description 2
Landscapes
- Optical Recording Or Reproduction (AREA)
- Moving Of The Head For Recording And Reproducing By Optical Means (AREA)
Abstract
Description
【発明の詳細な説明】
技術分野
本発明は光学式記録再生装置に関し、特に記録媒体の記
録面にスポット光を照射することにより情報の記録再生
を行う光学式記録再生装置における光ヘッドのフォーカ
ス引込み制御方式に関するものである。Detailed Description of the Invention Technical Field The present invention relates to an optical recording/reproducing device, and more particularly to focusing of an optical head in an optical recording/reproducing device that records/reproduces information by irradiating a recording surface of a recording medium with a spot light. This concerns the control method.
従来技術
従来、光ヘッドからのスポット光を記録ディスク媒体の
記録面から離れた位置から記録面上に正確に位置決めす
るフォーカス引込み技術を第４図及び第５図を用いて説
明する。2. Description of the Related Art A conventional focus pull-in technique for accurately positioning a spot light from an optical head on the recording surface of a recording disk medium from a position away from the recording surface will be described with reference to FIGS. 4 and 5.
第４図はフォーカス引込み用のフォーカス制御信号を生
成する回路である。媒体面（図示せず）からの反射光を
２分割型光検出器１により受光して２つの電気信号に変
換し、この２の検出信号の差を差動増幅器２で増幅して
フォーカス誤差信号として得、また２つの検出信号の和
を加算増幅器３で増幅してフォーカス和信号として得て
いる。FIG. 4 shows a circuit that generates a focus control signal for focus pull-in. Reflected light from the medium surface (not shown) is received by a two-part photodetector 1 and converted into two electrical signals, and the difference between these two detection signals is amplified by a differential amplifier 2 to produce a focus error signal. The sum of the two detection signals is amplified by the summing amplifier 3 to obtain a focus sum signal.
これ等フォーカス誤差信号とフォーカス和信号とはＡＧ
Ｃ回路４に入力される。このＡＧＣ回路４では、フォー
カス誤差信号をフォーカス和信号により割算することに
より、フォーカス誤差信号がＡＧＣ（自動利得制御）処
理されたＡＧＣ出力信号を得ている。These focus error signals and focus sum signals are AG
It is input to the C circuit 4. The AGC circuit 4 divides the focus error signal by the focus sum signal to obtain an AGC output signal in which the focus error signal has been subjected to AGC (automatic gain control) processing.
第５図はフォーカス引込み動作作時のＡＧＣ出力波形を
示したものである。フォーカスを引込む場合、光ヘッド
の対物レンズを媒体の遠くから徐々に媒体の記録面へ近
づけて行き、そのときのＡＧＣ出力波形によりフォーカ
ス引込みタイミングが決定されるようになっている。FIG. 5 shows the AGC output waveform during the focus pull-in operation. When retracting the focus, the objective lens of the optical head is gradually brought closer to the recording surface of the medium from a distance of the medium, and the timing of retracting the focus is determined by the AGC output waveform at that time.
このとき、媒体を覆うカバーガラス面で最初の合焦点（
フォーカス誤差信号であるＡＧＣ出力が零となる点）が
現われ、次に記録面で合焦点が再び現われる。At this time, the first focused point (
A point at which the AGC output, which is a focus error signal, becomes zero appears, and then a focused point appears again on the recording surface.
通常、媒体記録面での反射率は未記録時で３０％、配録
時で１５％程度であるのに対し、カバーガラス面での反
射率は数％程度である。しかしながら、ＡＧＣ回路４の
ＡＧＣ動作により、媒体記録面に対するカバーガラス面
合焦点でのＡＧＣ出力の振幅比は、未記録時で３０〜３
５％、記録時では更に大きく６０〜７０％程度となる。Normally, the reflectance on the recording surface of the medium is about 30% when unrecorded and about 15% when recorded, while the reflectance on the cover glass surface is about several percent. However, due to the AGC operation of the AGC circuit 4, the amplitude ratio of the AGC output at the focus point on the cover glass surface to the recording surface of the medium is 30 to 3 when not recording.
5%, and during recording, it becomes even larger, about 60 to 70%.
そこで、未記録時の媒体記録面合焦点でのＡＧＣ出力最
大振幅の８０％をレベル検出してフォカスを引込むタイ
ミングとしているのである。この様子が第５図の波形に
示されている。Therefore, 80% of the maximum amplitude of the AGC output at the focal point on the recording surface of the medium when no recording is being performed is detected as the timing for focusing. This state is shown in the waveform of FIG.
この様に、従来のフォーカス引込み方式では、常にＡＧ
Ｃが動作しているために、カバーガラスの合焦点位置と
媒体記録面の合焦点位置とのＡＧＣ出力信号の最大振幅
差が、第５図に示す如く小となり、カバーガラス面上で
フォーカスサーボを引込んでしまう危険性が生しる。In this way, in the conventional focus pull-in method, the AG
Since C is operating, the maximum amplitude difference of the AGC output signal between the focused point position of the cover glass and the focused point position of the medium recording surface becomes small as shown in Fig. 5, and the focus servo is activated on the cover glass surface. There is a risk that it will be drawn in.
発明の目的
本発明の目的は、サーボ引込み時に誤ってカバーガラス
面上で引込むことがないようにした光学式記録再生装置
を提供することである。OBJECTS OF THE INVENTION An object of the present invention is to provide an optical recording/reproducing device that prevents the servo from being accidentally pulled onto the surface of a cover glass during servo retraction.
発明の構成
本発明によれば、記録媒体の記録面にスポット光を照射
することにより情報の記録再生を行う光学式記録再生装
置であって、前記記録媒体を紅た光を受光して電気信号
に変換する２分割型の光検出器と、前記光検出器からフ
ォーカス誤差信号を得る差動増幅器と、前記光検出器か
らフォーカス和信号を得る加算増幅器と、前記フォーカ
ス誤差信号を前記フォーカス和信号により割算した信号
を得るＡＧＣ回路と、フォーカス引込み動作期間中、前
記ＡＧＣ回路のＡＧＣ動作を制限して増幅率を所定値以
下に制御する手段を有することを特徴とする光学式記録
再生装置が得られる。Structure of the Invention According to the present invention, there is provided an optical recording and reproducing apparatus that records and reproduces information by irradiating a recording surface of a recording medium with a spot light, the recording medium receiving red light and generating an electrical signal. a two-split photodetector for converting the focus error signal into the focus sum signal; a differential amplifier for obtaining a focus error signal from the photodetector; a summing amplifier for obtaining a focus sum signal from the photodetector; An optical recording/reproducing device comprising: an AGC circuit that obtains a signal divided by; and means for controlling the amplification factor to a predetermined value or less by limiting the AGC operation of the AGC circuit during a focus pull-in operation period. can get.
実施例
次に、本発明の実施例について図面を参照して説明する
。Embodiments Next, embodiments of the present invention will be described with reference to the drawings.
第１図は本発明の一実施例の構成図である。２分割光検
出器１により２分割された信号は差動増幅器２及び加算
増幅器３に夫々入力される。差動増幅器２の出力である
フォーカス誤差信号１１と、加算増幅器３の出力である
フォーカス和信号１２とはＡＧＣ回路４に入力される。FIG. 1 is a block diagram of an embodiment of the present invention. The signals divided into two by the two-split photodetector 1 are input to a differential amplifier 2 and a summing amplifier 3, respectively. A focus error signal 11 that is the output of the differential amplifier 2 and a focus sum signal 12 that is the output of the summing amplifier 3 are input to the AGC circuit 4.
次に、ＡＧＣ回路４の内部構成を説明する。フォーカス
誤差信号１１は掛算器５に、フォーカス和信号は掛算器
６に夫々供給される。掛算器６の出力と基準電圧１５と
が減算器７で減算され、減算器７の出力は電圧制限回路
８に印加される。電圧制限回路８の出力である制御電流
１４は掛算器５及び掛算器６に入力される。Next, the internal configuration of the AGC circuit 4 will be explained. The focus error signal 11 is supplied to a multiplier 5, and the focus sum signal is supplied to a multiplier 6. The output of the multiplier 6 and the reference voltage 15 are subtracted by a subtracter 7, and the output of the subtracter 7 is applied to a voltage limiting circuit 8. Control current 14, which is the output of voltage limiting circuit 8, is input to multiplier 5 and multiplier 6.
ＡＧＣ回路４では、フォーカス誤差信号１１に制御電流
１４を掛けた信号をＡＧＣ出力１３として出力する。制
御電流１４はフォーカス和信号の変化に応じて変化し、
制御電流１４とフォーカス誤差信号１１とを掛算器５に
人力することによりＡＧＣ出力１３はフォーカス誤差信
号をフォーカス和信号で割算したものとなる。The AGC circuit 4 outputs a signal obtained by multiplying the focus error signal 11 by the control current 14 as an AGC output 13. The control current 14 changes according to changes in the focus sum signal,
By manually inputting the control current 14 and the focus error signal 11 to the multiplier 5, the AGC output 13 becomes the result of dividing the focus error signal by the focus sum signal.
尚、スイッチ９は外部制御信号１６により切換え制御さ
れ、ａ側の場合、減算器７の出力は電圧制限回路８へ入
力され、ｂ側の場合、減算器７の出力はそのまま制御電
流１４となって掛算器５゜６へ供給される。The switch 9 is switched and controlled by an external control signal 16, and when it is on the a side, the output of the subtracter 7 is input to the voltage limiting circuit 8, and when it is on the b side, the output of the subtracter 7 becomes the control current 14 as it is. and is supplied to a multiplier 5.6.
第２図はフォーカス引込み動作時のＡＧＣ回路４の増幅
率の変化をフォーカス和信号との関係において示したも
のである。第１図の回路において、フォーカス引込み時
は外部制御信号１６によりスイッチ９がａ側に切換えら
れ、よって減算器７の出力は電圧制限回路８を介して制
御電流１４となる。FIG. 2 shows the change in the amplification factor of the AGC circuit 4 during the focus pull-in operation in relation to the focus sum signal. In the circuit shown in FIG. 1, when the focus is pulled in, the switch 9 is switched to the a side by the external control signal 16, so that the output of the subtracter 7 becomes the control current 14 via the voltage limiting circuit 8.
そのために、フォーカス引込み動作中は、電圧制限回路
８か動作して、ＡＧＣ回路４のＡＧＣ動作を制限して、
第２図に示す様に最大増幅率を一定値ＡＯに制限してい
るのである。Therefore, during the focus pull-in operation, the voltage limiting circuit 8 operates to limit the AGC operation of the AGC circuit 4.
As shown in FIG. 2, the maximum amplification factor is limited to a constant value AO.
このときのフォーカス誤差信号とＡＧＣ出力波形を第３
図に示す。これはフォーカス引込みの際、対物レンズを
媒体の遠くから近づけた時の出力変化である。媒体記録
面の反射率は未記録時で３０％、記録時で１５％程度に
対し、カバーガラス面の反射率は数％程度である。従っ
て、フォーカス誤差信号１１では、カバーガラス面と記
録面とでの最大振幅差が大きい。The focus error signal and AGC output waveform at this time are
As shown in the figure. This is the change in output when the objective lens is brought closer to the medium from a distance during focus pull-in. The reflectance of the recording surface of the medium is about 30% when unrecorded and about 15% when recorded, while the reflectance of the cover glass surface is about several percent. Therefore, in the focus error signal 11, the maximum amplitude difference between the cover glass surface and the recording surface is large.
しかし、ＡＧＣ出力では、第３図に示すように、カバー
ガラス面と記録面とでの最大振幅が接近する。そこで、
本実施例では、フォーカス引込み動作中は、スイッチ制
御信号１６によりスイッチ９がａ側となってＡＧＣ回路
４内の電圧制限回路８を動作させることにより、ＡＧＣ
回路４の増幅率を制限している。つまり、ＡＧＣ出力１
３において、カバーガラス面と記録面とのピークレベル
に充分な差がとれるように、ＡＧＣ回路４の最大増幅率
を制限しているのである。However, in the AGC output, as shown in FIG. 3, the maximum amplitudes at the cover glass surface and the recording surface are close to each other. Therefore,
In this embodiment, during the focus pull-in operation, the switch 9 is set to the a side by the switch control signal 16, and the voltage limiting circuit 8 in the AGC circuit 4 is operated.
The amplification factor of the circuit 4 is limited. In other words, AGC output 1
3, the maximum amplification factor of the AGC circuit 4 is limited so that there is a sufficient difference in peak level between the cover glass surface and the recording surface.
そして、ＡＧＣ出力１３の最大振幅の８０％をレベル検
出してフォーカスを引込み、フォーカス引込み終了後は
、スイッチ制御信号１６によりスイッチ９をｂ側として
、電圧制限回路８を不活性とすることにより、通常ＡＧ
Ｃ動作によりフォーカシング制御を行なっている。Then, the focus is pulled in by detecting the level of 80% of the maximum amplitude of the AGC output 13, and after the focus pull-in is completed, the switch 9 is set to the b side by the switch control signal 16, and the voltage limiting circuit 8 is made inactive. Normal AG
Focusing control is performed by C operation.
第２図に示した如くフォーカス引込み動作中は、ＡＧＣ
回路４の最大増幅率はＡＯに制限されるので、カバーガ
ラス面でのＡＧＣ回路４の最大増幅がＡＯＪ、：＠ｌ限
される様に予め設計しておくことにより、カバーガラス
面と媒体記録面とのＡＧＣ出力最大振幅差が大きくなり
、第３図に示すＡＧＣ出力波形を得ることができるので
ある。As shown in Figure 2, during the focus pull-in operation, the AGC
Since the maximum amplification factor of the circuit 4 is limited to AO, by designing in advance so that the maximum amplification of the AGC circuit 4 on the cover glass surface is limited to AOJ, :@l, it is possible to The maximum amplitude difference in the AGC output with respect to the surface becomes large, and the AGC output waveform shown in FIG. 3 can be obtained.
発明の効果
以上述べた如く、本発明によれば、フォーカス引込み動
作中はＡＧＣ回路のＡＧＣ動作を制限してそのゲインを
一定値ＡＯ以下になる様にしているので、カバーガラス
面と媒体記録面とを確実に認識できるようになり、簡単
な構成で安定したフォーカスサーボ引込みが可能になる
という効果がある。Effects of the Invention As described above, according to the present invention, during the focus pull-in operation, the AGC operation of the AGC circuit is limited so that the gain is below a certain value AO, so that the cover glass surface and the medium recording surface are This has the effect of enabling stable focus servo pull-in with a simple configuration.
第１図は本発明の実施例のブロック図、第２図はフォー
カス和信号とＡＧＣ回路のゲインの変化との関係を示す
図、第３図は本発明の実施例によるフォーカス誤差信号
とＡＧＣ出力との波形を示す図、第４図は従来のフォー
カス引込み動作のための回路ブロック図、第５図は第４
図の回路のＡＧＣ出力波形を示す図である。
主要部分の符号の説明
１・・・・・・２分割型光検出器
２・・・・・・差動増幅器 ９・・・・・・スイッ
チ３・・・・・・加算増幅器
４・・・・・・ＡＧＣ回路
８・・・・・・電圧制限回路FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a diagram showing the relationship between the focus sum signal and the change in gain of the AGC circuit, and FIG. 3 is a focus error signal and AGC output according to the embodiment of the present invention. FIG. 4 is a circuit block diagram for conventional focus pull-in operation, and FIG.
It is a figure which shows the AGC output waveform of the circuit of a figure. Explanation of symbols of main parts 1...2-split photodetector 2...Differential amplifier 9...Switch 3...Summing amplifier 4... ... AGC circuit 8 ... Voltage limiting circuit
Claims (1)
より情報の記録再生を行う光学式記録再生装置であって
、前記記録媒体を経た光を受光して電気信号に変換する
２分割型の光検出器と、前記光検出器からフォーカス誤
差信号を得る差動増幅器と、前記光検出器からフォーカ
ス和信号を得る加算増幅器と、前記フォーカス誤差信号
を前記フォーカス和信号により割算した信号を得るＡＧ
Ｃ回路と、フォーカス引込み動作期間中、前記ＡＧＣ回
路のＡＧＣ動作を制限して増幅率を所定値以下に制御す
る手段を有することを特徴とする光学式記録再生装置。(1) An optical recording and reproducing device that records and reproduces information by shining a spot light onto the recording surface of a recording medium, which is a two-segment type optical recording and reproducing device that receives light that has passed through the recording medium and converts it into an electrical signal. a photodetector, a differential amplifier that obtains a focus error signal from the photodetector, a summing amplifier that obtains a focus sum signal from the photodetector, and obtains a signal obtained by dividing the focus error signal by the focus sum signal. AG
1. An optical recording/reproducing apparatus comprising: a C circuit; and means for controlling an amplification factor to a predetermined value or less by limiting an AGC operation of the AGC circuit during a focus pull-in operation period.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2243237A JP2630043B2 (en) | 1990-09-13 | 1990-09-13 | Optical recording / reproducing device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2243237A JP2630043B2 (en) | 1990-09-13 | 1990-09-13 | Optical recording / reproducing device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH04123321A true JPH04123321A (en) | 1992-04-23 |
| JP2630043B2 JP2630043B2 (en) | 1997-07-16 |
Family
ID=17100881
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2243237A Expired - Fee Related JP2630043B2 (en) | 1990-09-13 | 1990-09-13 | Optical recording / reproducing device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2630043B2 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH06124470A (en) * | 1992-10-09 | 1994-05-06 | Nec Corp | Generation circuit of position error signal |
| US7193945B2 (en) | 2001-10-19 | 2007-03-20 | Sony Computer Entertainment Inc. | Method for determining type of recording media |
| US7274630B2 (en) | 2002-03-20 | 2007-09-25 | Kabushiki Kaisha Toshiba | Layer discriminating focus control apparatus, optical disk apparatus, and methods therefore |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5919248A (en) * | 1982-07-23 | 1984-01-31 | Sanyo Electric Co Ltd | Servo gain control circuit |
| JPS6012823U (en) * | 1983-07-05 | 1985-01-28 | 株式会社ケンウッド | Focus servo device |
-
1990
- 1990-09-13 JP JP2243237A patent/JP2630043B2/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5919248A (en) * | 1982-07-23 | 1984-01-31 | Sanyo Electric Co Ltd | Servo gain control circuit |
| JPS6012823U (en) * | 1983-07-05 | 1985-01-28 | 株式会社ケンウッド | Focus servo device |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH06124470A (en) * | 1992-10-09 | 1994-05-06 | Nec Corp | Generation circuit of position error signal |
| US7193945B2 (en) | 2001-10-19 | 2007-03-20 | Sony Computer Entertainment Inc. | Method for determining type of recording media |
| US7274630B2 (en) | 2002-03-20 | 2007-09-25 | Kabushiki Kaisha Toshiba | Layer discriminating focus control apparatus, optical disk apparatus, and methods therefore |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2630043B2 (en) | 1997-07-16 |
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