JP3763413B2 - Tracking control method for optical disk apparatus - Google Patents

Description

【００５０】
ここで、各モードにおけるトラッキング制御回路の動作を説明する。最初に、通常のトラッキングサーボＯＮ状態のときの動作を説明する。
【００５１】
まず、図１に示すように、図示しない光ピックアップから検出されたトラッキングエラー信号は、ＬＰＦ１及びＨＰＦ５によって、低域処理及び高域処理がなされる。ＬＰＦ１及びＨＰＦ５を通した信号は、サーボ加算器２にて加算され、これによって位相補償が行なわれる。
【００５２】
次いで、加算された信号はサーボ乗算器３にてＴＧ倍され、ジャンプ切換スイッチ４を介してトラッキングドライブ出力とされる。
【００５３】
このトラッキングドライブ出力は、図示しない外部のトラッキングアクチュエータドライバに制御信号として供給され、光ピックアップのトラッキングアクチュエータを駆動する。これら一連の動作により、図２に示すように、スポット２０が例えばトラックＮ上をトレースする。
【００５４】
次に、トラックジャンプ、すなわちスポット２０を他のトラックから所定トラックＮへ移動させるときの動作について説明する。
【００５５】
トラックジャンプにおいては、図１に示すように、図示しないマイコンにより、ジャンプ切換スイッチ４がジャンプ信号＝１となり、滑り止め切換スイッチ９が滑り止め信号＝０となる。
【００５６】
したがって、トラッキングエラー信号は、ＬＰＦ１、ＨＰＦ５、サーボ加算器２、及びサーボ乗算器３にて処理された後、ＬＰＦ６に入力される。
【００５７】
このＬＰＦ６によって、トラッキングエラー信号を増幅した信号における低域成分の平均値が演算される。ＬＰＦ６では、カットオフ周波数は、ノイズを除去するが光ピックアップの偏心周波数は除去しないような値に選ばれる。このＬＰＦ６の出力は、ノイズ等を除いた値であり、アクチュエータの平均的な駆動電圧である。したがって、対物レンズの傾きを示しているとも言える。
【００５８】
次いで、上記ＬＰＦ６の出力は、キックホールド回路７に入力されることにより、マイコンからキックパルス信号が与えられた時に保持される。すなわち、トラックジャンプにおいては、マイコンからのキックパルス信号がキックホールド回路７に入力された時点でのＬＰＦ６の出力を保持するようになっており、これによって、トラックジャンプのためのキック、つまり加速を開始した瞬間にＬＰＦ６から出力された値がキックホールド回路７により保持されることになる。
【００５９】
次いで、キックホールド回路７にて保持された出力値に、マイコンからのキックパルス信号がキック加算器８にて加算印加される。
【００６０】
ここで、キックの時間は光ディスクの回転時間と比較して十分短く、かつキックする距離は光ピックアップの稼働距離に比べて十分小さいので、キックホールド回路７の出力は、キック中の図示しない対物レンズの傾きと言える。したがって、キック加算器８によるキックパルス信号の加算は、現在の対物レンズの傾きを基準としてキックパルス信号を与えることを意味している。
【００６１】
すなわち、従来のアナログサーボでは、キックホールド回路７に相当する機能が無かったために、対物レンズの傾きがどのようであっても、キックパルス信号の形が同じとなり、これによって、トラッキング制御が不安定になる要因の一つとなっていた。これに対して、本実施の形態では、この対物レンズの傾き、すなわち、スポット２０のディスク半径方向の位置を考慮して、トラッキング制御が行われるようになっている。
【００６２】
次に、トラックジャンプにおけるキックパルス信号の与え方を、図１及び図３に基づいて説明する。なお、この図３は、例えば、トラックＮからトラックＮ＋１に上記スポット２０が移動するときのように、トラック１本キックの状態を表している。
【００６３】
まず、図示しないマイコンは、図３に示すように、トラックジャンプする時に、高さＫＨ及び幅ＫＷの第１のキックパルス信号を図１に示すキック加算器８に与える。この高さＫＨ及び幅ＫＷからなる第１のキックパルス信号は、アクチュエータ感度に合わせた固有値である。
【００６４】
したがって、トラッキングドライブ出力としては、キックホールド回路７にて保持したＬＰＦ６の保持値に上記の第１のキックパルス信号を付加したものとなっている。すなわち、トラックジャンプ時には、キックホールド回路７の出力を基準としたトラッキングドライブ出力が与えられる。
【００６５】
この第１のキックパルス信号にキックホールド回路７の保持値を付加したトラッキングドライブ出力によって対物レンズを一気に加速する。なお、後述するように、本実施の形態においては、次の第２のキックパルス信号にて、ＴＥmax ／２の値を検出するようになっているが、この第１のキックパルス信号を出力する期間つまり幅ＫＷにおいては、ＴＥmax ／２の値の誤検出を防止するために、この期間をブラインド期間としている。すなわち、この期間においては、トラッキングエラー信号をマスキングをして入力しないようにし、これによって、ＴＥmax 値の検出処理をしないようになっている。
【００６６】
次いで、第２のキックパルス信号として上記第１のキックパルス信号の１／２の高さである高さＫＨ／２からなるキック（加速）パルスを与える。この第２のキックパルス信号が第１のキックパルス信号における高さＫＨよりも小さいのは、加速度を小さくして次に来るブレーキによる減速とのギャップを少なくするためである。すなわち、加速と減速とのギャップが大きいと、対物レンズに大きな正負の加速度が加わることになり、その結果、移動距離は加速度の２次積分となるので、距離の誤差が生じやすくなり、不安定要因となるためである。
【００６７】
上記第２のキックパルス信号は、図３に示すように、トラッキングエラー信号が最大値ＴＥmax の半分、つまりＴＥmax ／２になったときに終了する。なお、同図においては、例えばトラックＮからトラックＮ＋１にジャンプするときの状態を示しているので、トラックＮとトラックＮ＋１との中間でトラッキングエラー信号が最大値ＴＥmax となり、スポット２０のトラックＮ＋１への移動途中でトラッキングエラー信号がＴＥmax ／２となり、このときに第２のキックパルス信号が終了する。
【００６８】
次に、ブレーキパルス信号として高さＢＨ及び幅ＢＷのブレーキ（減速）パルスを与える。ブレーキパルス信号もまた、アクチュエータ感度に合わせた固有値である。
【００６９】
このブレーキパルス信号は、加速のための第１及び第２のキックパルス信号と関連し、正確な本数のキックを行うためには、トラックジャンプ終了後のスポット２０のトラックに対する偏心位置及びトラックを横切る方向の速度成分がほぼ０になるように設定されることが好ましい。なお、これら設定値が悪くても次に述べる滑り止めによってトラッキング引込み、つまりトラックへの収束はスムーズに行われるが、キック本数の精度が減少する。
【００７０】
次に、滑り止め、つまりトラック引込みの動作について説明する。
【００７１】
ブレーキが終了すると、図３に斜線で示すように、滑り止めに移行する。ここで、滑り止めというのは、光ディスクでは、スポット２０がトラックに対して非接触であるため、摩擦がなく、滑るイメージとなるため、この用語を用いている。なお、図３では、１本キックの後の滑り止めについて示しているが、２本以上のキックについても同じ処理にて滑り止めを行うことができる。
【００７２】
滑り止め期間中は、図１に示す滑り止め切換スイッチ９が１側に固定される。
【００７３】
したがって、ＬＰＦ６の出力が乗算器１０・１１によって、Ｇ１倍又はＧ２倍される。Ｇ１の値は例えば２、Ｇ２の値は例えば４である。これら乗算器１０・１１の出力は、マイコンにより指定される信号ＧＵＰにて切り換えられる倍率切換スイッチ１２により選択される。
【００７４】
また、同図に示す信号ＴＣＲＳは、上記スポット２０がトラックに対してどの位置にあるかを示す信号であり、オントラックの所定近傍の時に０となる。すなわち、信号ＴＣＲＳは、図２に示すように、例えばトラックＮ±１／４以内の位置にスポット２０の中心がある時に０となり、また、このトラックＮ±１／４以内の位置をオントラック所定近傍以内という。
【００７５】
図４に示すように、信号ＴＣＲＳ＝０のときは、トラッキングエラー信号の傾きは正相である一方、信号ＴＣＲＳ＝１のときは、トラッキングエラー信号の傾きは逆相になる。すなわち、信号ＴＣＲＳ＝１のときに、通常のトラッキングサーボをかけると逆効果になる。
【００７６】
したがって、信号ＴＣＲＳ＝０のときは、引込み時サーボ切換スイッチ１４を０側に倒して、通常のトラッキングサーボをかける。そして、信号ＴＣＲＳ＝１になった瞬間に、倍率切換スイッチ１２の出力がホールド回路１３によってホールドされると共に、引込み時サーボ切換スイッチ１４が１側に倒れる。これによって、そのときのトラッキングエラー信号がゼロクロスするときの傾きの大小つまりはスポットのトラックを横切る方向の速度成分を示すホールド回路１３の出力が、スイッチ９・４を経てトラッキングドライブ出力とされる。このトラッキングドライブ出力は、乗算器１０・１１によって増幅されたものとなっているので、ブレーキ力が調整されることになる。
【００７７】
このように、トラックジャンプにおいては、キックパルス信号又はブレーキパルス信号に基づきトラッキングドライブ出力として印加される。
【００７８】
このとき、本実施の形態の光ディスク装置のトラッキング制御方法では、トラッキングドライブ出力の低域成分を保持し、その保持信号にキックパルス信号又はブレーキパルス信号を付加してトラッキングドライブ出力とされる。
【００７９】
したがって、従来であれば、スポット２０のディスク半径方向の位置がどこにあっても、トラックジャンプするときには、同じ大きさのキックパルス信号又はブレーキパルス信号をトラッキングドライブ出力として印加していたので、制御の不安定要因となっていたが、本実施の形態では、トラックジャンプ直前のスポットのディスク半径方向の位置に基づいてキックパルス信号又はブレーキパルス信号が付加され、トラッキングドライブ出力として印加されるので、高速・安定にトラックジャンプからトラッキング引込み、及びトラッキングサーボＯＮ状態に移行することができる。
【００８０】
さらに、本制御においては、殆ど処理の増加を招かず、比較的容易な方法で上記のことを達成することができる。
【００８１】
また、本実施の形態の光ディスク装置のトラッキング制御方法では、トラックジャンプにおけるブレーキパルス信号の印加が終了し、トラック引込みの段階に移行したときに、スポット２０がオントラック所定近傍から外れる時には、外れる直前におけるトラッキングドライブ出力の低域成分に基づいてトラッキングドライブ出力が与えられる。
【００８２】
したがって、スポットのディスク半径方向の位置及びトラックを横切る方向の速度成分に基づいてトラッキングドライブ出力が与えられるので、高速・安定にトラッキング引込み及びトラッキングサーボＯＮ状態に移行することができる。
【００８３】
また、本実施の形態の光ディスク装置のトラッキング制御方法では、特に、トラックジャンプにおけるブレーキパルス信号の印加が終了し、トラック引込みの段階に移行した場合に、スポットがオントラック所定近傍から外れる時の、外れる直前のトラッキングドライブ出力における低域成分の保持を２倍及び４倍の２段階に調節することができる。
【００８４】
その結果、スポットがオントラック所定近傍から外れる時のトラッキングドライブ出力を２段階に調節することができる。
【００８５】
したがって、トラック引込みの段階に移行したときのトラッキング制御を高精度に行うことができる。
【００８６】
〔実施の形態２〕
本発明の他の実施の形態について図１に基づいて説明すれば、以下の通りである。なお、説明の便宜上、前記の実施の形態１の図面に示した部材と同一の機能を有する部材については、同一の符号を付し、その説明を省略する。
【００８７】
本実施の形態の光ディスク装置のトラッキング制御方法では、トラックジャンプ直前におけるトラッキングエラー信号の上記ローパスフィルタ（ＬＰＦ）の出力をメモリーに保持しておき、トラック引込みを経てトラッキングサーボに移行する時に、その保持信号を初期値としてトラッキングサーボを開始するようになっている。
【００８８】
すなわち、図１に示すように、ＬＰＦ１及びＨＰＦ５の演算処理を行う場合に、図示しないメモリーを遅延手段として使用しているが、そのうち、ＬＰＦ１の更新をしないようにしておくことで、トラッキングサーボ移行時にスムーズにトラッキングサーボを開始することができる。
【００８９】
これによって、偏心量の多い光ディスクの場合にトラッキングサーボ動作の連続性が良くなり、ショックを和らげることができる。なお、このとき、ＨＰＦ５については、常に処理を継続している。
【００９０】
【発明の効果】
本発明の光ディスク装置のトラッキング制御方法では、スポットのディスク半径方向の位置及びトラックを横切る方向の速度成分に基づいてトラッキングドライブ出力が与えられるので、高速・安定にトラッキング引込み及びトラッキングサーボＯＮ状態に移行することができるという効果を奏する。
【図面の簡単な説明】
【図１】 本発明に係る光ディスク装置のトラッキング制御回路の一構成例を示す回路図である。
【図２】 上記光ディスク装置に備えられた光ディスクの要部を拡大して示す模式図である。
【図３】 上記トラッキング制御回路において、トラックジャンプからトラック引込みに移行するときの制御動作を示すタイムチャートである。
【図４】 上記トラッキング制御回路におけるトラック引込み時の制御動作を示すタイムチャートである。
【符号の説明】
４ ジャンプ切換スイッチ
６ ＬＰＦ
７ キックホールド回路
８ キック加算器
９ 滑り止め切換スイッチ
１０ 乗算器
１１ 乗算器
１３ ホールド回路
１４ 引込み時サーボ切換スイッチ
２０ スポット[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a tracking control method for an optical disc apparatus that optically reads a signal recorded on an optical disc such as a CD (Compact Disc), an MD (Mini Disc), or a VD (Video Disk).
[0002]
[Prior art]
A tracking servo device of an optical disk apparatus that optically reads a signal recorded on an optical disk is an apparatus for tracking servo so that a signal can be read along a track of the optical disk.
[0003]
By the way, the tracking servo described above is operated after the spot focused on the disk surface by the laser beam emitted from the optical pickup moves to a predetermined track. When jumping, the tracking servo is off.
[0004]
That is, as shown in FIG. 2 which is an explanatory diagram of the present invention, when the spot 20 is out of a predetermined track, the spot 20 generally moves in a direction perpendicular to the track at a predetermined speed. Reach that track. When the movement of the spot 20 is braked and positioned near the track N, for example, it is possible to shift to a normal tracking servo ON state.
[0005]
However, in this case, even if the spot 20 is positioned in the vicinity of the track N, the tracking servo cannot be turned on if the movement speed between the tracks is high. This is because even if the tracking servo is turned on instantaneously, the track is immediately removed.
[0006]
Accordingly, it is necessary to apply an appropriate braking force to the spot 20, but in order to determine the braking force, two parameters of the speed of moving the disk surface of the spot 20 and the current position must be used. An appropriate braking force cannot be determined.
[0007]
For example, Patent Documents 1 to 4 disclose conventional techniques related to control when shifting from the track jump to the normal tracking servo ON state.
[0008]
In the above-mentioned patent document 1, if the spot is between tracks N to N + 1, control is performed so that the spot is forcibly returned to the direction of track N. That is, the technique disclosed in this publication adjusts the braking force according to the spot position. However, in the technique of this publication, the braking force works only in one direction. Therefore, there is a problem that it is easy to run away, that is, slippery. In the above example, it is easy to slide in the direction of the track N-1.
[0009]
That is, as described above, originally, unless the position and speed of the spot are known, the magnitude of the braking force should not be determined. It should also be taken into account that the track itself has a speed due to the eccentricity of the optical disk. Furthermore, it cannot be applied to a so-called virgin track in which no RF signal exists.
[0010]
Further, the above-mentioned Patent Document 2 discloses a tracking control suitable for forming a wobbling pit in the servo area of an optical disc and performing fast pull-in by detecting the wobbling pit.
[0011]
However, the technique disclosed in this publication cannot be used when the optical disk is not a wobbling pit formed in the servo area.
[0012]
Furthermore, in the above-mentioned patent document 3, 6 to 9 positions of the spot with respect to the track are detected, and two directions are detected. Then, the braking force is determined according to the combined state of these, thereby providing tracking control with a short pull-in time.
[0013]
This disclosed technique has a certain effect because it considers the position and direction of the spot, but is still insufficient because it does not consider the speed. Further, the processing is very complicated, and a dedicated high-speed DSP is required. Furthermore, the step amount is large.
[0014]
Next, in the above-mentioned patent document 4, it is considered that the movement speed between tracks is reduced when the tracking error signal is within a predetermined level and this state continues for a certain time. At this time, the tracking servo is turned on.
[0015]
As a result, even a virgin track can be reliably pulled into a desired track. In this method, the spot speed and position are detected to some extent. Also, eccentricity is considered.
[0016]
However, the technique disclosed in this publication has to wait until it is time to reliably retract the tracking servo to the ON state, and no reference is made to a brake for retracting at high speed. Also, the speed detection method in the technique of this publication is based on the condition that the tracking error signal has a certain width within a certain time, and does not directly detect the speed. Therefore, the accuracy of speed detection becomes insufficient. For example, when the tracking error signal oscillates within a certain width, the speed is detected small even though the actual speed is large. is doing.
[0017]
[Patent Document 1]
Japanese Patent Laid-Open No. Sho 61-253676 (published on November 11, 1986)
[0018]
[Patent Document 2]
Japanese Unexamined Patent Publication No. 63-144429 (released on June 16, 1988)
[0019]
[Patent Document 3]
Japanese Patent Laid-Open No. 2-62730 (published March 2, 1990)
[0020]
[Patent Document 4]
Japanese Patent Laid-Open No. 5-282682 (published on October 29, 1993)
[0021]
[Problems to be solved by the invention]
As described above, in the conventional tracking control method of the optical disc apparatus, both of the two parameters of the movement speed between tracks and the position are not taken into consideration, or very complicated control is required even if they are taken into consideration. It has become a thing. And (1) It is easy to run away because the control is rough, (2) It takes time for the pull-in process, and (3) The algorithm is very complicated.
[0022]
The present invention has been made in view of the above-described conventional problems, and its object is to make a transition from track jump to tracking pull-in and tracking servo ON in a relatively easy method and at a high speed and stably. An object of the present invention is to provide a tracking control method for an optical disc apparatus.
[0023]
[Means for Solving the Problems]
In order to solve the above problem, the tracking control method of the optical disc device of the present invention performs tracking servo by tracking drive output based on a tracking error signal, while tracking jump or tracking by output of a tracking drive based on a kick pulse signal or a brake pulse signal. In a tracking control method of an optical disc apparatus that performs track pull-in, A predetermined position in the vicinity of an on-track target track is set as an on-track predetermined vicinity, and a signal output as a tracking drive signal during tracking servo is passed through a low-pass filter (LPF). A signal obtained by passing the tracking error signal through a high-pass filter (HPF), and a signal indicating the velocity component of the spot, When the track is pulled in after applying the brake pulse signal, the tracking servo is performed within the on-track predetermined vicinity in order to perform the track pull-in within the predetermined on-track vicinity, Spot On-track predetermined neighborhood When you leave The tracking drive output when it deviates from the on-track predetermined range, noise is removed. Included in the tracking drive output Optical pickup eccentric frequency And spot velocity components Is passed through a low-pass filter (LPF) having a cutoff frequency that is not removed, and a tracking drive output obtained by multiplying the output of the low-pass filter (LPF) by a multiplier is given.
[0024]
According to the above method, when the application of the brake pulse signal in the track jump is completed and the track is pulled in, when the spot deviates from the on-track predetermined vicinity, the low frequency component of the tracking drive output immediately before the decoupling occurs. A tracking drive output is provided based on the velocity component in the direction across the spot track.
[0025]
Therefore, since the tracking drive output is given based on the position of the spot in the radial direction of the disk and the velocity component in the direction crossing the track, the tracking pull-in and tracking servo ON states can be made at high speed and stability.
[0026]
The tracking control method for an optical disc apparatus according to the present invention is the tracking control method for an optical disc device described above, wherein the low frequency component obtained through the low pass filter (LPF) of the tracking drive output immediately before the track jump is retained during the track jump. In addition, a kick pulse signal or a brake pulse signal is added to the holding signal to obtain a tracking drive output, while the kick pulse signal is added subsequent to the first kick pulse signal and the first kick pulse signal. The second kick pulse signal having a voltage lower than that of the first kick pulse signal, and the second kick pulse signal is obtained when the tracking error signal is half of the maximum value of the tracking error signal. And the second kick pad Upon termination of the scan signals it is characterized by providing a brake pulse signal.
[0027]
That is, in the track jump, the tracking drive output is applied based on the kick pulse signal or the brake pulse signal.
[0028]
At this time, according to the above method, the low frequency component of the tracking drive output immediately before the track jump is held, and a kick pulse signal or a brake pulse signal is added to the holding signal to obtain a tracking drive output.
[0029]
Therefore, conventionally, when the track jump is performed regardless of the position of the spot in the radial direction of the disk, the kick pulse signal or the brake pulse signal having the same magnitude is applied as the tracking drive output, so that control is not possible. It was a stability factor. However, in the present invention, a kick pulse signal or a brake pulse signal is added based on the position of the spot immediately before the track jump in the disc radial direction, applied as a tracking drive output, and the kick pulse signal is the first kick pulse signal. And a second kick pulse signal having a voltage lower than that of the first kick pulse signal, which is added subsequent to the first kick pulse signal, and the second kick pulse signal is a tracking error signal. Ends when the tracking error signal becomes half of the maximum value of the tracking error signal, and a brake pulse signal is given upon completion of the second kick pulse signal. The servo can be switched on.
[0030]
Further, the control hardly increases the processing and can be achieved by a relatively easy method.
[0031]
The tracking control method for an optical disk apparatus according to the present invention is the tracking control method for an optical disk apparatus described above, wherein the tracking drive output given outside the predetermined vicinity of the on-track is a tracking drive output when the predetermined vicinity of the on-track is deviated. The low-frequency component obtained through the low-pass filter (LPF) is a signal holding a value twice and four times the low-frequency component.
[0032]
According to the above method, when the application of the brake pulse signal in the track jump is completed and the process moves to the track pull-in stage, the low frequency component of the tracking drive output immediately before the spot is removed when the spot is deviated from the on-track predetermined vicinity. Can be adjusted in two stages, two times and four times.
[0033]
As a result, the tracking drive output when the spot deviates from the on-track predetermined vicinity can be adjusted in two stages.
[0034]
Therefore, the tracking control when shifting to the track pull-in stage can be performed with high accuracy.
[0035]
The tracking control method for an optical disc apparatus according to the present invention is the tracking control method for an optical disc device described above, wherein the tracking error signal passes through a low-pass filter (LPF) and a high-pass filter (HPF) connected in parallel. After being added and multiplied by the servo adder and the servo multiplier, it is output as a tracking drive output, while the output of the low-pass filter (LPF) of the tracking error signal immediately before the track jump is held in the memory, and The memory of the low-pass filter (LPF) is not updated, and the processing of the high-pass filter (HPF) is always continued. When shifting to the tracking servo through the track pull-in, the memory holding signal is used as the initial value for tracking. It is characterized by starting the turbo.
[0036]
According to the above method, when shifting to the tracking servo through the track pull-in, the output of the low-pass filter (LPF) of the tracking error signal immediately before the track jump is given as the tracking drive output in the tracking servo.
[0037]
Therefore, in the case of an optical disk with a large amount of eccentricity, the continuity of the tracking servo operation is improved and the shock can be reduced. As a result, the tracking servo can be started smoothly when the tracking servo shifts.
[0038]
DETAILED DESCRIPTION OF THE INVENTION
[Embodiment 1]
An embodiment of the present invention will be described below with reference to FIGS.
[0039]
As shown in FIG. 1, the tracking control circuit of the optical disk apparatus according to the present embodiment has an LPF (Low Pass Filter) 1, a servo adder 2, a servo multiplier 3, and a jump switch 4 connected in series. While the tracking error signal is inputted to the LPF 1, the tracking drive output is taken out from the jump changeover switch 4.
[0040]
An HPF (High Pass Filter) 5 is connected in parallel to the LPF 1, whereby the tracking error signal passes through the LPF 1 and the HPF 5 and is added by the servo adder 2.
[0041]
The jump switch 4 is switched from the 0 side to the 1 side by a jump signal output from an external microcomputer (not shown).
[0042]
On the other hand, the output of the servo multiplier 3 is branched and connected to the LPF 6. The LPF 6 is connected to a kick hold circuit 7, a kick adder 8, and an anti-slip switch 9 in order, and an output terminal of the anti-slip switch 9 is connected to a one-side terminal of the jump switch 4. Yes.
[0043]
The kick adder 8 adds a kick pulse signal from a microcomputer (not shown). Further, the anti-slip changeover switch 9 is switched from the 0 side to the 1 side by an anti-slip signal output from a microcomputer (not shown).
[0044]
Furthermore, a multiplier 10 and a multiplier 11 are connected in parallel to the output side of the LPF 6, and outputs of the multiplier 10 and the multiplier 11 are respectively a 0-side terminal and a 1-side terminal of the magnification changeover switch 12. It is connected to the. The magnification changeover switch 12 is switched between the 0 side and the 1 side by a GUP signal from a microcomputer (not shown).
[0045]
Further, the output of the magnification changeover switch 12 is connected to the 1 side terminal of the servo changeover switch 14 at the time of pulling through the hold circuit 13. The output of the servo multiplier 3 is connected to the 0-side terminal of the pull-in servo switch 14. The pull-in servo switch 14 is switched between the 0 side and the 1 side by a signal TCRS from a microcomputer (not shown).
[0046]
Further, the output terminal of the pull-in servo switch 14 is connected to the one-side terminal of the anti-slip switch 9.
[0047]
In the tracking control circuit having the above-described configuration, the tracking servo ON state, the track jump or the track pull-in is switched by switching the jump switch 4 by the jump signal from the microcomputer and the non-slip switch 9 by the slip signal from the microcomputer. Switch to 3 mode.
[0048]
Table 1 shows a summary of the switching modes of each jump switching switch 4 and anti-slip switching switch 9 in each mode.
[0049]
[Table 1]

[0050]
Here, the operation of the tracking control circuit in each mode will be described. First, the operation when the normal tracking servo is ON will be described.
[0051]
First, as shown in FIG. 1, a tracking error signal detected from an optical pickup (not shown) is subjected to low-frequency processing and high-frequency processing by LPF 1 and HPF 5. The signals that have passed through the LPF 1 and the HPF 5 are added by the servo adder 2, thereby performing phase compensation.
[0052]
Next, the added signal is TG-multiplied by the servo multiplier 3 and used as a tracking drive output via the jump changeover switch 4.
[0053]
This tracking drive output is supplied as a control signal to an external tracking actuator driver (not shown) to drive the tracking actuator of the optical pickup. By a series of these operations, the spot 20 traces, for example, on the track N as shown in FIG.
[0054]
Next, a description will be given of a track jump, that is, an operation when the spot 20 is moved from another track to a predetermined track N.
[0055]
In the track jump, as shown in FIG. 1, the jump switch 4 is set to jump signal = 1 and the anti-slip switch 9 is set to non-slip signal = 0 by a microcomputer (not shown).
[0056]
Accordingly, the tracking error signal is processed by the LPF 1, HPF 5, servo adder 2, and servo multiplier 3 and then input to the LPF 6.
[0057]
The LPF 6 calculates the average value of the low frequency components in the signal obtained by amplifying the tracking error signal. In the LPF 6, the cutoff frequency is selected so as to remove noise but not the eccentric frequency of the optical pickup. The output of the LPF 6 is a value excluding noise and the like, and is an average driving voltage of the actuator. Therefore, it can be said that it shows the inclination of the objective lens.
[0058]
Next, the output of the LPF 6 is input to the kick hold circuit 7 and is held when a kick pulse signal is given from the microcomputer. That is, in the track jump, the output of the LPF 6 at the time when the kick pulse signal from the microcomputer is input to the kick hold circuit 7 is held. The value output from the LPF 6 at the instant of start is held by the kick hold circuit 7.
[0059]
Next, the kick pulse signal from the microcomputer is added and applied to the output value held by the kick hold circuit 7 by the kick adder 8.
[0060]
Here, the kick time is sufficiently shorter than the rotation time of the optical disk, and the kicking distance is sufficiently shorter than the working distance of the optical pickup, so that the output of the kick hold circuit 7 is an objective lens (not shown) during the kick. It can be said that the slope of the. Therefore, the addition of the kick pulse signal by the kick adder 8 means that the kick pulse signal is given based on the current inclination of the objective lens.
[0061]
That is, in the conventional analog servo, since there is no function corresponding to the kick hold circuit 7, the shape of the kick pulse signal is the same regardless of the inclination of the objective lens, which makes the tracking control unstable. It became one of the factors. In contrast, in the present embodiment, tracking control is performed in consideration of the inclination of the objective lens, that is, the position of the spot 20 in the disk radial direction.
[0062]
Next, how to give the kick pulse signal in the track jump will be described with reference to FIGS. FIG. 3 shows a state where one track is kicked, for example, when the spot 20 moves from the track N to the track N + 1.
[0063]
First, as shown in FIG. 3, the microcomputer (not shown) provides a first kick pulse signal having a height KH and a width KW to the kick adder 8 shown in FIG. The first kick pulse signal having the height KH and the width KW is an eigenvalue that matches the actuator sensitivity.
[0064]
Therefore, the tracking drive output is obtained by adding the first kick pulse signal to the hold value of the LPF 6 held by the kick hold circuit 7. That is, at the time of track jump, a tracking drive output based on the output of the kick hold circuit 7 is given.
[0065]
The objective lens is accelerated at once by the tracking drive output obtained by adding the hold value of the kick hold circuit 7 to the first kick pulse signal. As will be described later, in the present embodiment, the value of TEmax / 2 is detected by the next second kick pulse signal, but this first kick pulse signal is output. In the period, that is, the width KW, this period is a blind period in order to prevent erroneous detection of the value of TEmax / 2. That is, during this period, the tracking error signal is not masked and input, thereby preventing the TEmax value detection process.
[0066]
Next, a kick (acceleration) pulse having a height KH / 2 which is ½ the height of the first kick pulse signal is applied as the second kick pulse signal. The reason why the second kick pulse signal is smaller than the height KH in the first kick pulse signal is to reduce the acceleration and reduce the gap with the subsequent deceleration by the brake. In other words, if the gap between acceleration and deceleration is large, large positive and negative accelerations are applied to the objective lens. As a result, the movement distance is a quadratic integral of acceleration, and therefore, an error in distance is likely to occur and is unstable. This is because it becomes a factor.
[0067]
As shown in FIG. 3, the second kick pulse signal ends when the tracking error signal becomes half of the maximum value TEmax, that is, TEmax / 2. In the figure, for example, the state when jumping from the track N to the track N + 1 is shown, so that the tracking error signal becomes the maximum value TEmax between the track N and the track N + 1, and the spot 20 moves to the track N + 1. During the movement, the tracking error signal becomes TEmax / 2, and at this time, the second kick pulse signal ends.
[0068]
Next, a brake (deceleration) pulse having a height BH and a width BW is applied as a brake pulse signal. The brake pulse signal is also an eigenvalue that matches the actuator sensitivity.
[0069]
This brake pulse signal is related to the first and second kick pulse signals for acceleration. In order to perform an accurate number of kicks, the eccentric position of the spot 20 with respect to the track after the track jump and the track are crossed. It is preferable to set the velocity component in the direction to be substantially zero. Even if these set values are bad, tracking pull-in, that is, convergence to the track is smoothly performed by the anti-slip described below, but the accuracy of the number of kicks is reduced.
[0070]
Next, the operation of slip prevention, that is, track pull-in will be described.
[0071]
When the braking is finished, as shown by hatching in FIG. Here, the term “slip prevention” is used in the optical disc because the spot 20 is not in contact with the track, and thus there is no friction and the image is slid. Although FIG. 3 shows the slip prevention after one kick, the slip prevention can be performed by the same process for two or more kicks.
[0072]
During the anti-slip period, the anti-slip switch 9 shown in FIG. 1 is fixed to the 1 side.
[0073]
Therefore, the output of the LPF 6 is multiplied by G1 or G2 by the multipliers 10 and 11. The value of G1 is 2, for example, and the value of G2 is 4, for example. The outputs of the multipliers 10 and 11 are selected by a magnification changeover switch 12 that is switched by a signal GUP designated by a microcomputer.
[0074]
The signal TCRS shown in the figure is a signal indicating where the spot 20 is located with respect to the track, and becomes 0 when it is in the vicinity of a predetermined on-track. That is, as shown in FIG. 2, the signal TCRS becomes 0 when, for example, the center of the spot 20 is located within the track N ± 1/4, and the position within the track N ± 1/4 is set to the on-track predetermined position. It is within the vicinity.
[0075]
As shown in FIG. 4, when the signal TCRS = 0, the tracking error signal has a positive phase, while when the signal TCRS = 1, the tracking error signal has a negative phase. That is, when the signal TCRS = 1, applying the normal tracking servo has an adverse effect.
[0076]
Therefore, when the signal TCRS = 0, the servo switch 14 at the time of pulling is moved to the 0 side to perform normal tracking servo. At the moment when the signal TCRS = 1, the output of the magnification changeover switch 12 is held by the hold circuit 13, and the servo changeover switch 14 is pulled down to the 1 side when retracted. As a result, the output of the hold circuit 13 indicating the magnitude of the inclination when the tracking error signal at that time crosses zero, that is, the velocity component in the direction crossing the spot track, is made the tracking drive output via the switches 9.4. Since the tracking drive output is amplified by the multipliers 10 and 11, the braking force is adjusted.
[0077]
Thus, in the track jump, the tracking drive output is applied based on the kick pulse signal or the brake pulse signal.
[0078]
At this time, in the tracking control method of the optical disk apparatus of the present embodiment, the low frequency component of the tracking drive output is held, and a kick pulse signal or a brake pulse signal is added to the held signal to obtain a tracking drive output.
[0079]
Therefore, conventionally, when the track jump is performed regardless of the position of the spot 20 in the radial direction of the disk, the kick pulse signal or the brake pulse signal having the same magnitude is applied as the tracking drive output. In this embodiment, a kick pulse signal or a brake pulse signal is added based on the position in the disc radial direction of the spot immediately before the track jump and is applied as a tracking drive output.・ Stable transition from track jump to tracking pull-in and tracking servo ON state.
[0080]
Further, in this control, the above can be achieved by a relatively easy method with almost no increase in processing.
[0081]
Further, in the tracking control method of the optical disc apparatus of the present embodiment, when the application of the brake pulse signal in the track jump is completed and the process moves to the track pull-in stage, when the spot 20 deviates from the on-track predetermined vicinity, immediately before the release. A tracking drive output is provided based on the low frequency component of the tracking drive output at.
[0082]
Therefore, since the tracking drive output is given based on the position of the spot in the radial direction of the disk and the velocity component in the direction crossing the track, the tracking pull-in and tracking servo ON states can be made at high speed and stability.
[0083]
Further, in the tracking control method of the optical disk device of the present embodiment, particularly when the application of the brake pulse signal in the track jump is finished and the process moves to the track pull-in stage, when the spot deviates from the on-track predetermined vicinity, It is possible to adjust the holding of the low frequency component in the tracking drive output immediately before the deviation to two stages of 2 times and 4 times.
[0084]
As a result, the tracking drive output when the spot deviates from the on-track predetermined vicinity can be adjusted in two stages.
[0085]
Therefore, the tracking control when shifting to the track pull-in stage can be performed with high accuracy.
[0086]
[Embodiment 2]
The following will describe another embodiment of the present invention with reference to FIG. For convenience of explanation, members having the same functions as those shown in the drawings of the first embodiment are given the same reference numerals and explanation thereof is omitted.
[0087]
In the tracking control method of the optical disk apparatus according to the present embodiment, the output of the low-pass filter (LPF) of the tracking error signal immediately before the track jump is held in the memory, and the tracking error signal is held when the tracking servo is shifted to the tracking servo. The tracking servo is started with the signal as an initial value.
[0088]
That is, as shown in FIG. 1, when performing arithmetic processing of LPF1 and HPF5, a memory (not shown) is used as a delay means. Of these, by not updating LPF1, tracking servo transition is performed. Sometimes tracking servo can be started smoothly.
[0089]
As a result, in the case of an optical disk with a large amount of eccentricity, the continuity of the tracking servo operation is improved and the shock can be reduced. At this time, the processing is always continued for the HPF 5.
[0090]
【The invention's effect】
In the tracking control method of the optical disk apparatus according to the present invention, the tracking drive output is given based on the position of the spot in the radial direction of the disk and the velocity component in the direction crossing the track. There is an effect that can be done.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing a configuration example of a tracking control circuit of an optical disc apparatus according to the present invention.
FIG. 2 is a schematic diagram showing an enlarged main part of an optical disc provided in the optical disc apparatus.
FIG. 3 is a time chart showing a control operation when shifting from track jump to track pull-in in the tracking control circuit.
FIG. 4 is a time chart showing a control operation at the time of track pull-in in the tracking control circuit.
[Explanation of symbols]
4 Jump selector switch
6 LPF
7 Kick hold circuit
8 Kick adder
9 Non-slip switch
10 multiplier
11 Multiplier
13 Hold circuit
14 Servo selector switch when retracted
20 spots

Claims (5)

In a tracking control method for an optical disc apparatus that performs tracking servo by tracking drive output based on a tracking error signal, while performing track jump or track pull-in by tracking drive output based on a kick pulse signal or a brake pulse signal,
For a track that is the target of on-track, set a predetermined location in the vicinity as the on-track predetermined neighborhood,
A signal output as a tracking drive signal during tracking servo is obtained by passing a tracking error signal through a low-pass filter (LPF) and a tracking error signal through a high-pass filter (HPF). A signal indicative of a velocity component,
When the track is pulled in after the brake pulse signal is applied, the tracking servo is performed within the on-track predetermined vicinity in order to perform the track pull-in within the on-track predetermined vicinity, and when the spot deviates from the on-track predetermined vicinity , the on-track predetermined vicinity The tracking drive output at the time of deviating from the above is passed through a low pass filter (LPF) having a cutoff frequency that removes noise but does not remove the eccentric frequency and spot velocity components of the optical pickup included in the tracking drive output. A tracking control method for an optical disc apparatus, characterized by providing a tracking drive output obtained by converting a magnification of an output of a low-pass filter (LPF) by a multiplier. During the track jump, the low frequency component obtained through the low pass filter (LPF) of the tracking drive output immediately before the track jump is held, and a kick pulse signal or a brake pulse signal is added to the hold signal to obtain a tracking drive output,
The kick pulse signal includes a first kick pulse signal and a second kick pulse signal having a voltage lower than that of the first kick pulse signal, which is added subsequent to the first kick pulse signal, and The second kick pulse signal ends when the tracking error signal becomes half of the maximum value of the tracking error signal,
2. The tracking control method for an optical disk apparatus according to claim 1, wherein a brake pulse signal is given upon completion of the second kick pulse signal. The tracking drive output given outside the predetermined vicinity of the on-track is either a value twice or four times the low-frequency component obtained through the low-pass filter (LPF) of the tracking drive output outside the predetermined vicinity of the on-track . 3. The tracking control method for an optical disk apparatus according to claim 1, wherein the signal is a signal that is selected and held. The tracking error signal passes through a low-pass filter (LPF) and a high-pass filter (HPF) connected in parallel, is added and multiplied by a servo adder and a servo multiplier, and is then output as a tracking drive output. ,
The output of the low-pass filter (LPF) of the tracking error signal immediately before the track jump is held in the memory, the memory of the low-pass filter (LPF) is not updated, and the processing of the high-pass filter (HPF) Always continue,
4. The tracking control method for an optical disk apparatus according to claim 1, wherein when the control shifts to tracking servo through track pull-in, tracking servo is started with the retention signal in the memory as an initial value. When tracking servo is performed by the tracking drive output based on the tracking error signal, the tracking error signal is obtained by passing the tracking error signal through a low pass filter (LPF) and the tracking error signal is obtained by passing the tracking error signal through a high pass filter (HPF). While providing a tracking drive signal including a signal indicating the velocity component of the spot ,
When performing a track jump from a spot on a certain track to another predetermined track, and further performing a control of drawing the spot onto the predetermined track,
At the time of the track jump, a tracking drive output based on a kick pulse signal or a brake pulse signal is given,
When the track is pulled in, tracking servo is performed within a predetermined vicinity of the predetermined track, and when the spot deviates from the predetermined vicinity of the predetermined track, noise is removed from the tracking drive output when the spot deviates from the predetermined vicinity. Is passed through a low-pass filter (LPF) having a cutoff frequency that does not remove the eccentric frequency and spot velocity component of the optical pickup included in the tracking drive output, and the output of the low-pass filter (LPF) is converted by a multiplier. A tracking control method for an optical disc apparatus, characterized by providing a tracking drive output obtained in the above manner.

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