JPS6325803A - Magnetic recording circuit - Google Patents
Magnetic recording circuitInfo
- Publication number
- JPS6325803A JPS6325803A JP16871786A JP16871786A JPS6325803A JP S6325803 A JPS6325803 A JP S6325803A JP 16871786 A JP16871786 A JP 16871786A JP 16871786 A JP16871786 A JP 16871786A JP S6325803 A JPS6325803 A JP S6325803A
- Authority
- JP
- Japan
- Prior art keywords
- current
- track position
- current source
- write
- track
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 230000007423 decrease Effects 0.000 claims description 3
- 238000010586 diagram Methods 0.000 description 5
- 238000001514 detection method Methods 0.000 description 4
- 230000003247 decreasing effect Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 1
- 239000000284 extract Substances 0.000 description 1
- 230000005389 magnetism Effects 0.000 description 1
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/02—Recording, reproducing, or erasing methods; Read, write or erase circuits therefor
- G11B5/027—Analogue recording
- G11B5/035—Equalising
Landscapes
- Digital Magnetic Recording (AREA)
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
この発明は、記録メディアにデータを磁気によって記録
する磁気記録回路に係り、特に、記録メディアのトラッ
ク位置に応じた磁化電流の制御に関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording circuit for magnetically recording data on a recording medium, and particularly to control of magnetizing current according to the track position of the recording medium.
記録メディアとして用いられているフロッピィディスク
には、同心円状の記録用トラックが形成され、ディスク
を回転させながら外周側トランクからデータの磁気記録
が行われる。Concentric recording tracks are formed on a floppy disk used as a recording medium, and data is magnetically recorded from an outer trunk while rotating the disk.
フロッピィディスクでは、内外周によらず１トラツクに
対して同じ容量のデータを記録するので、記録密度は周
長ｄ短い内周はど高くなり、隣接ビット間隔が小さくな
って相互に波形干渉を起こす度合が大きくなる。そこで
、内周での分解能を高めるために、第４図に示すように
、トラックへの書込み電流■。を内周側■。、外周側Ｉ
、（Ｉ。In a floppy disk, the same amount of data is recorded on one track regardless of the inner or outer circumference, so the recording density is highest on the inner circumference, where the circumference is shorter (d), and the adjacent bit interval becomes smaller, causing mutual waveform interference. The degree increases. Therefore, in order to improve the resolution on the inner circumference, as shown in FIG. 4, the write current to the track is increased. ■ On the inner circumferential side. , outer circumferential side I
, (I.
〉■。）というように２段階に切り換えていた。〉■. ) and so on.
しかしながら、このような記録メディアの内外周の記録
用トラックの単純な２段階の切換えでは、高密度、高性
能化に対応することは不可能である。However, such a simple two-step switching of the recording tracks on the inner and outer peripheries of the recording medium cannot meet the demands for high density and high performance.
そこで、この発明は、記録メディアに対する磁気記録に
ついて、高密度化、高性能化を実現した磁気記録回路の
提供を目的とする。Therefore, an object of the present invention is to provide a magnetic recording circuit that achieves higher density and higher performance for magnetic recording on recording media.
この発明の磁気記録回路は、第１図に示すように、任意
の電流値に設定された定電流を出力する第１の電流源（
主電流源２）と、記録メディアのトラック位置を検出す
るトランク位置検出手段（トラックカウンタ１０）と、
このトランク位置検出手段（トラックカウンタ１０）に
よって検出されたトラック位置に応じて段階的に電流値
が増減するとともに、電流値の増減幅を任意に設定可能
な第２の電流源（補正電流源８）とを備え、第１および
第２の電流源（主電流源２、補正電流源８）が発生した
電流を加算して書込み電流（ライト電流ＩＩｇ）として
出力するものである。As shown in FIG. 1, the magnetic recording circuit of the present invention includes a first current source (
a main current source 2), a trunk position detection means (track counter 10) for detecting the track position of the recording medium,
The current value increases or decreases stepwise according to the truck position detected by the trunk position detection means (truck counter 10), and a second current source (correction current source 8 ), and the currents generated by the first and second current sources (main current source 2, correction current source 8) are added and output as a write current (write current IIg).
このように構成すると、記録メディアのトラ・ツク位置
に対応して書込み電流の制御を行い、記録の高密度化と
ともに′、高性能化を実現する。With this configuration, the write current is controlled in accordance with the track position of the recording medium, achieving higher recording density and higher performance.
以下、この発明の実施例を図面を参照して説明する。 Embodiments of the present invention will be described below with reference to the drawings.
第１図は、この発明の磁気記録回路の実施例を示す。FIG. 1 shows an embodiment of the magnetic recording circuit of the present invention.
第１図に示すように、第１の電流源として設置された主
電流源２は、磁気ヘッドに対するライト電流の基礎を成
す主定電流を発生し、この定電流は、外部端子４に接続
された抵抗６の値によって任意の値に加減される。As shown in FIG. 1, a main current source 2 installed as a first current source generates a main constant current that forms the basis of a write current to the magnetic head, and this constant current is connected to an external terminal 4. It can be adjusted to an arbitrary value depending on the value of the resistor 6.
この主電流源２に対して第２の電流源として補正電流？
ａ、８を設置し、この補正電流源８は、主電流源２が発
生する主たる定電流に対して、トラックカウンタ１０か
らの補正信号に応じて記録用トラック位置に対応する補
正定電流を出力するが、その場合、補正定電流は外部端
子１２に接続された抵抗１４の値によって任意に加減さ
れる。A correction current as a second current source for this main current source 2?
A, 8 is installed, and this correction current source 8 outputs a correction constant current corresponding to the recording track position in response to the correction signal from the track counter 10, with respect to the main constant current generated by the main current source 2. However, in that case, the correction constant current is arbitrarily adjusted by the value of the resistor 14 connected to the external terminal 12.
トラックカウンタ１０は、記録メディアの記録用トラッ
クの位置を検出するトランク位置検出手段として設置さ
れており、記録メディアの交換などに応じて加えられる
リセット信号Ｒによって初期設定された後、トラック位
置を表わすクロック信号ＣＫを計数してトラック位置を
表わす位置信号を発生する。The track counter 10 is installed as a trunk position detection means for detecting the position of a recording track of a recording medium, and after being initialized by a reset signal R applied when the recording medium is replaced, the track counter 10 indicates the track position. A position signal representing the track position is generated by counting the clock signal CK.
そして、主電流ｍ２が発生した主定電流と、補正型’ａ
源８がトラック位置に対応して発生した補正定電流は、
加算手段１６によって加算された後、書込み電流源１８
に加えられて、ライト電流Ｉ。Then, the main constant current generated by the main current m2 and the correction type 'a
The correction constant current generated by the source 8 in response to the track position is:
After being added by the adding means 16, the write current source 18
In addition to the write current I.
とじて書込み回路２０に加えられる。The signal is then added to the write circuit 20.
書込み回路２０は、磁気ヘッドのコイル２２の各端子２
４ａ、２４ｂにトランジスタなどからなるスイッチング
素子２６ａ、２６ｂを設置したものであり、スイッチン
グ素子２６ａ、２６ｂは、破線で示すようにライト信号
によって交互に開閉し、閉じられた側のスイッチング素
子２６ａまたはスイッチング素子２６ｂからコイル２２
にライト電流Ｉ、１が流れる。この場合、コイル２２は
、センタータップ２８に対して電源電圧ＶＣＣが加えら
れており、ライト電流Ｉ８の方向に応じて励磁されて記
録メディアに対して書込みデータを表わす磁気を発生し
、記録メディアには磁気によってデータを書き込むこと
ができる。The write circuit 20 connects each terminal 2 of the coil 22 of the magnetic head.
4a, 24b are provided with switching elements 26a, 26b made of transistors, etc., and the switching elements 26a, 26b are alternately opened and closed by a light signal as shown by the broken line, and the switching element 26a or the switching element on the closed side From element 26b to coil 22
A write current I,1 flows through. In this case, the power supply voltage VCC is applied to the center tap 28 of the coil 22, and the coil 22 is excited in accordance with the direction of the write current I8 to generate magnetism representing write data to the recording medium. can write data magnetically.
したがって、このような磁気記録回路では、第２図のＡ
に示すように、主電流源２による主定電流■。に対して
補正電流源８によるトラック位置に応じた補正定電流が
加算され、トラック位置に応じたライト電流■。がコイ
ル２２に供給される。Therefore, in such a magnetic recording circuit, A in FIG.
As shown, the main constant current ■ from the main current source 2. A correction constant current according to the track position by the correction current source 8 is added to the write current (2) according to the track position. is supplied to the coil 22.
ここで、全トランク数をｎ、書込み位置トラック番号を
ｍ、補正定電流の増加幅をΔＩ、主定電流をＩｏとする
と、ライト電流■。は、Ｉｗ ＝Ｉｏ ＋ （ｎ ｍ
） ・ΔＩとなる。この場合、特定のトラック数Ｎを
単位に補正定電流の制御をしてもよく、そのとき、補正
定電流の段階幅は、（ｎ−ｍ） ・ΔＩ／Ｎとなる。Here, if the total number of trunks is n, the write position track number is m, the increase width of the correction constant current is ΔI, and the main constant current is Io, then the write current is ■. is Iw = Io + (n m
) ・ΔI. In this case, the correction constant current may be controlled in units of a specific number of tracks N, in which case the step width of the correction constant current is (n-m)·ΔI/N.
そして、主定電流■。の値は抵抗６の値によって増減し
、また、補正電流の段階幅ΔＩは抵抗１４の値によって
増減することができ、主定電流Ｉ０の値を変えることな
く、補正定電流の段階幅Δ■を大きくすると、第２図の
破線Ｂに示すように、ライト電流Ｉいの傾きを増加させ
ることができる。And the main constant current ■. The value of can be increased or decreased by the value of the resistor 6, and the step width ΔI of the correction current can be increased or decreased by the value of the resistor 14, and the step width Δ■ of the correction constant current can be increased or decreased by changing the value of the main constant current I0. By increasing I, the slope of the write current I can be increased, as shown by the broken line B in FIG.
このようにしてトランクの位置に応じてライト電流Ｉ。In this way the light current I depends on the position of the trunk.
の制御を行い、記録メディアのトラック位置に応じて高
密度化、高性能化のデータ記録を行うことができる。It is possible to perform high-density and high-performance data recording according to the track position of the recording medium.
第３図は、第１図に示した磁気記録回路の具体的な回路
構成例を示す。FIG. 3 shows a specific example of the circuit configuration of the magnetic recording circuit shown in FIG.
主電流源２は、基′＄電圧源３０にトランジスタ３２．
３４、抵抗３６および端子４ａ、４ｂに接続された抵抗
６からなるカレントミラー回路を抵抗３８を介して設置
したものであり、基準電圧源３０の電圧値■、。ｆｌお
よび抵抗６の値に応じて主定電流Ｉ。が設定される。The main current source 2 has a base voltage source 30 connected to a transistor 32.
34, a current mirror circuit consisting of a resistor 36 and a resistor 6 connected to the terminals 4a and 4b is installed via a resistor 38, and the voltage value of the reference voltage source 30 is . The main constant current I depending on the value of fl and resistor 6. is set.
トラックカウンタ１０は、７組のＴフリップフロップ回
路によって構成され、トラック位置を表わすクロック信
号ＣＫを計数し、その計数出力を各反転出力−ｄ−から
取り出している。The track counter 10 is constituted by seven sets of T flip-flop circuits, counts clock signals CK representing track positions, and extracts the count output from each inverted output -d-.
また、補正電流源８は、基準電圧源４０の基準電圧■、
。ｆ２によってベース電圧が設定されたトランジスタ４
２．４４．４６．４８．５０．５２．５４を設置し、各
トランジスタ４２〜５４のエミッタ側に補正基準電流値
を決定する抵抗５６．５８．６０．６２．６４．６６．
６８を設置している。補正定電流を段階的に変化させる
ため、抵抗５６の値をＲとすると、抵抗５８はＲ／２、
抵抗６０はＲ／４、抵抗６２はＲ／８、抵抗６４はＲ／
１６、抵抗６６はＲ／３２、抵抗６８はＲ／６４の値に
設定されている。そして、各トランジスタ４２〜５４に
対して並列にスイッチング素子としてのトランジスタ７
０．７２．７４．７６．７８．８０．８２を設置し、各
トランジスタ７０〜８２のベースに対してトラックカウ
ンタ１０の反転出力間を加え、トランジスタ７０〜８２
の導通、遮断を行う。Further, the correction current source 8 has a reference voltage of the reference voltage source 40;
. Transistor 4 whose base voltage is set by f2
2.44.46.48.50.52.54 are installed, and a resistor 56.58.60.62.64.66. is installed on the emitter side of each transistor 42-54 to determine the correction reference current value.
68 are installed. In order to change the correction constant current stepwise, if the value of the resistor 56 is R, the value of the resistor 58 is R/2,
Resistor 60 is R/4, resistor 62 is R/8, and resistor 64 is R/4.
16, the resistor 66 is set to a value of R/32, and the resistor 68 is set to a value of R/64. A transistor 7 as a switching element is connected in parallel to each of the transistors 42 to 54.
0.72.74.76.78.80.82, add the inverted output of the track counter 10 to the base of each transistor 70-82,
Conducts conduction and disconnection.
トランジスタ７０〜８２のトラックカウンタ１０の計数
出力による選択的な導通、遮断によってトランジスタ４
２〜５４に得られた電流は、トランジスタ８４．８６お
よび抵抗８８．９０からなるカレントミラー回路を介し
てトランジスタ９２．９４、抵抗９６および端子１２ａ
、１２ｂ間に外付けされた抵抗１４からなるカレントミ
ラー回路に加えられて、補正定電流が出力される。The transistor 4 is selectively turned on and off by the counting output of the track counter 10 of the transistors 70 to 82.
The current obtained in terminals 2 to 54 is passed through a current mirror circuit consisting of a transistor 84.86 and a resistor 88.90 to a transistor 92.94, a resistor 96, and a terminal 12a.
, 12b, and is added to a current mirror circuit consisting of an external resistor 14, and a correction constant current is output.
補正電流源８で得られた補正定電流と、主電流源２から
の主定電流Ｉ０は、書込み電流源１８の入力部における
ライン上で加算されて、その加算電流値が書込み電流源
１８から吸い出される。The correction constant current obtained by the correction current source 8 and the main constant current I0 from the main current source 2 are added on the line at the input part of the write current source 18, and the added current value is added from the write current source 18. being sucked out.
書込み電流源１８は、トランジスタ９７．９８および抵
抗１００．１０２からなるカレントミラー回路に主定電
流Ｉ０および補正定電流の加算値であるライト電流■。The write current source 18 supplies a write current (2), which is the sum of the main constant current I0 and the correction constant current, to a current mirror circuit consisting of transistors 97, 98 and resistors 100, 102.
を流し、このライト電流１、をトランジスタ１０４．１
０６および抵抗ｌＯ８，１１０からなるカレントミラー
回路を介して出力し、書込み回路２０に流す。flows, and this write current 1 is passed through the transistor 104.1.
06 and resistors 108 and 110, and is sent to the write circuit 20.
書込み回路２０は、スイッチング素子としてのトランジ
スタ２６ａ、２６ｂによって差動スイッチ回路を構成し
ており、トランジスタ２６ａ、２６ｂはライト信号ＷＤ
によってスイッチングするフリップフロップ回路１１２
の非反転出力Ｑおよび反転出力間によって交互にスイッ
チングする。The write circuit 20 configures a differential switch circuit by transistors 26a and 26b as switching elements, and the transistors 26a and 26b receive a write signal WD.
A flip-flop circuit 112 switching by
It alternately switches between the non-inverting output Q and the inverting output.
この結果、コイル２２に対してライト電流Ｉいの流れる
方向が反転し、必要なデータが記録メディアに書き込ま
れる。As a result, the direction in which the write current I flows with respect to the coil 22 is reversed, and necessary data is written to the recording medium.
このような磁気記録回路によれば、記録メディアのトラ
ック位置に応じたライト電流Ｉｕ＋が得られ、磁気記録
の高密度化、高性能化を図ることができる。According to such a magnetic recording circuit, a write current Iu+ can be obtained depending on the track position of the recording medium, and it is possible to achieve higher density and higher performance of magnetic recording.
以上説明したように、この発明によれば、記録メディア
のトラック位置を検出し、そのトラック位置に応じてラ
イト電流を加減することができ、磁気記録の高密度化、
高性能化を図って、磁気記録の信鯨性を高めることがで
きる。As explained above, according to the present invention, it is possible to detect the track position of a recording medium and adjust the write current according to the track position, thereby increasing the density of magnetic recording.
It is possible to improve the reliability of magnetic recording by improving its performance.
第１図はこの発明の磁気記録回路の実施例を示すブロッ
ク図、第２図は第１図に示した磁気記録回路によるライ
ト電流の制御を示す図、第３図は第１図に示した磁気記
録回路の具体的な回路構成例を示す回路図、第４図は従
来のライト電流の制御を示す図である。
２・・・第１の電流源としての主電流源、８・・・第２
の電流源としての補正電流源、１０・・・トラック位置
検出手段としてのトラックカウンタ。
第２図FIG. 1 is a block diagram showing an embodiment of the magnetic recording circuit of the present invention, FIG. 2 is a diagram showing write current control by the magnetic recording circuit shown in FIG. 1, and FIG. 3 is a block diagram showing the control of write current by the magnetic recording circuit shown in FIG. FIG. 4 is a circuit diagram showing a specific circuit configuration example of a magnetic recording circuit, and FIG. 4 is a diagram showing conventional write current control. 2... Main current source as the first current source, 8... Second
a correction current source as a current source; 10... a track counter as a track position detection means; Figure 2
Claims (1)
源と、 記録メディアのトラック位置を検出するトラック位置検
出手段と、 このトラック位置検出手段によって検出されたトラック
位置に応じて段階的に電流値が増減するとともに、電流
値の増減幅を任意に設定可能な第２の電流源とを備え、 第１および第２の電流源が発生した電流を加算して書込
み電流として出力することを特徴とする磁気記録回路。[Claims] A first current source that outputs a constant current set to an arbitrary current value, a track position detecting means for detecting a track position of a recording medium, and a track detected by the track position detecting means. It is equipped with a second current source whose current value increases and decreases stepwise according to the position, and whose range of increase/decrease in current value can be arbitrarily set, and which adds the currents generated by the first and second current sources. A magnetic recording circuit characterized by outputting a write current.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16871786A JPS6325803A (en) | 1986-07-17 | 1986-07-17 | Magnetic recording circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16871786A JPS6325803A (en) | 1986-07-17 | 1986-07-17 | Magnetic recording circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS6325803A true JPS6325803A (en) | 1988-02-03 |
Family
ID=15873136
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP16871786A Pending JPS6325803A (en) | 1986-07-17 | 1986-07-17 | Magnetic recording circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6325803A (en) |
Cited By (18)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0438703A (en) * | 1990-06-04 | 1992-02-07 | Nec Corp | Writing current setting circuit for floppy disk device |
| JPH04319504A (en) * | 1991-04-18 | 1992-11-10 | Teac Corp | Disk device |
| US6987632B2 (en) | 2003-07-22 | 2006-01-17 | Matsushita Electric Industral Co., Ltd. | Systems for conditional servowriting |
| US6995942B2 (en) | 2002-12-30 | 2006-02-07 | Matsushita Electric Industrial Co., Ltd. | Systems for WORF improvement |
| US6995937B2 (en) | 2002-12-27 | 2006-02-07 | Matsushita Electric Industrial Co., Ltd. | Methods using extended servo patterns with multi-pass servowriting and self-servowriting |
| US6999266B1 (en) | 2002-12-30 | 2006-02-14 | Matsushita Electric Industrial Co., Ltd. | Methods for WORF improvement |
| US6999264B2 (en) | 2002-12-27 | 2006-02-14 | Matsushita Electric Industrial Co., Ltd. | Methods for variable multi-pass servowriting and self-servowriting |
| US7019925B2 (en) | 2003-04-02 | 2006-03-28 | Matsushita Electric Industrial Co., Ltd. | Variable frequency chevron in printed media reference pattern to improve servo demodulation |
| US7027244B2 (en) | 2002-12-27 | 2006-04-11 | Matsushita Electric Industrial Co., Ltd. | Systems for self-servowriting using write-current variation |
| US7106548B2 (en) | 2003-07-22 | 2006-09-12 | Matsushita Electric Industrial Co., Ltd. | Methods for WORF improvement in conditional servowriting |
| US7106543B1 (en) | 2002-12-27 | 2006-09-12 | Matsushita Electric Industrial Co., Ltd. | Methods for self-servowriting with multiple passes per servowriting step |
| US7130146B2 (en) | 2005-03-16 | 2006-10-31 | Matsushita Electric Industrial Co., Ltd. | Two-pass-per-track servo burst patterns |
| US7136251B2 (en) | 2003-12-24 | 2006-11-14 | Matsushita Electric Industrial, Co., Ltd. | Methods for WORF improvement in conditional servowriting |
| US7149043B2 (en) | 2002-12-27 | 2006-12-12 | Matsushita Electric Industrial Co., Ltd. | Methods for self-servowriting using write-current variation |
| US7180695B2 (en) | 2002-12-27 | 2007-02-20 | Matsushita Electric Industrial Co., Ltd. | Systems for self-servowriting with multiple passes per servowriting step |
| US7190546B2 (en) | 2002-12-27 | 2007-03-13 | Matsushita Electric Industrial Co., Ltd. | Systems using extended servo patterns with variable multi-pass servowriting and self-servowriting |
| US7206148B2 (en) | 2003-04-02 | 2007-04-17 | Matsushita Electric Industrial Co., Ltd. | Variable frequency chevron in printed media reference pattern to improve servo demodulation |
| US7227714B2 (en) | 2003-07-22 | 2007-06-05 | Matsushita Electric Industrial Co., Ltd. | Methods for conditional servowriting |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS51137405A (en) * | 1975-05-23 | 1976-11-27 | Fujitsu Ltd | Write current control system for magnetic disc device |
-
1986
- 1986-07-17 JP JP16871786A patent/JPS6325803A/en active Pending
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS51137405A (en) * | 1975-05-23 | 1976-11-27 | Fujitsu Ltd | Write current control system for magnetic disc device |
Cited By (23)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0438703A (en) * | 1990-06-04 | 1992-02-07 | Nec Corp | Writing current setting circuit for floppy disk device |
| JPH04319504A (en) * | 1991-04-18 | 1992-11-10 | Teac Corp | Disk device |
| US6999264B2 (en) | 2002-12-27 | 2006-02-14 | Matsushita Electric Industrial Co., Ltd. | Methods for variable multi-pass servowriting and self-servowriting |
| US7199962B1 (en) | 2002-12-27 | 2007-04-03 | Matsushita Electric Industrial Co., Ltd. | Systems using extended servo patterns with multi-pass servowriting and self-servowriting |
| US6995937B2 (en) | 2002-12-27 | 2006-02-07 | Matsushita Electric Industrial Co., Ltd. | Methods using extended servo patterns with multi-pass servowriting and self-servowriting |
| US7245451B2 (en) | 2002-12-27 | 2007-07-17 | Matsushita Electric Industrial Co., Ltd. | Methods using extended servo patterns with variable multi-pass servowriting and self-servowriting |
| US7149043B2 (en) | 2002-12-27 | 2006-12-12 | Matsushita Electric Industrial Co., Ltd. | Methods for self-servowriting using write-current variation |
| US7190546B2 (en) | 2002-12-27 | 2007-03-13 | Matsushita Electric Industrial Co., Ltd. | Systems using extended servo patterns with variable multi-pass servowriting and self-servowriting |
| US7027244B2 (en) | 2002-12-27 | 2006-04-11 | Matsushita Electric Industrial Co., Ltd. | Systems for self-servowriting using write-current variation |
| US7099105B2 (en) | 2002-12-27 | 2006-08-29 | Matsushita Electric Industrial Co., Ltd. | Systems for selective multi-pass servowriting and self-servowriting |
| US7180695B2 (en) | 2002-12-27 | 2007-02-20 | Matsushita Electric Industrial Co., Ltd. | Systems for self-servowriting with multiple passes per servowriting step |
| US7106543B1 (en) | 2002-12-27 | 2006-09-12 | Matsushita Electric Industrial Co., Ltd. | Methods for self-servowriting with multiple passes per servowriting step |
| US7180696B2 (en) | 2002-12-27 | 2007-02-20 | Matsushita Electric Industrial Co., Ltd. | Methods for selective multi-pass servowriting and self-servowriting |
| US7167335B1 (en) | 2002-12-27 | 2007-01-23 | Matsushita Electric Industrial Co., Ltd. | Systems for variable multi-pass servowriting and self-servowriting |
| US6999266B1 (en) | 2002-12-30 | 2006-02-14 | Matsushita Electric Industrial Co., Ltd. | Methods for WORF improvement |
| US6995942B2 (en) | 2002-12-30 | 2006-02-07 | Matsushita Electric Industrial Co., Ltd. | Systems for WORF improvement |
| US7019925B2 (en) | 2003-04-02 | 2006-03-28 | Matsushita Electric Industrial Co., Ltd. | Variable frequency chevron in printed media reference pattern to improve servo demodulation |
| US7206148B2 (en) | 2003-04-02 | 2007-04-17 | Matsushita Electric Industrial Co., Ltd. | Variable frequency chevron in printed media reference pattern to improve servo demodulation |
| US7106548B2 (en) | 2003-07-22 | 2006-09-12 | Matsushita Electric Industrial Co., Ltd. | Methods for WORF improvement in conditional servowriting |
| US7227714B2 (en) | 2003-07-22 | 2007-06-05 | Matsushita Electric Industrial Co., Ltd. | Methods for conditional servowriting |
| US6987632B2 (en) | 2003-07-22 | 2006-01-17 | Matsushita Electric Industral Co., Ltd. | Systems for conditional servowriting |
| US7136251B2 (en) | 2003-12-24 | 2006-11-14 | Matsushita Electric Industrial, Co., Ltd. | Methods for WORF improvement in conditional servowriting |
| US7130146B2 (en) | 2005-03-16 | 2006-10-31 | Matsushita Electric Industrial Co., Ltd. | Two-pass-per-track servo burst patterns |
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