WO2002011129A1 - Method for writing information into a magnetic tape at different depth - Google Patents
Method for writing information into a magnetic tape at different depth Download PDFInfo
- Publication number
- WO2002011129A1 WO2002011129A1 PCT/NL2001/000582 NL0100582W WO0211129A1 WO 2002011129 A1 WO2002011129 A1 WO 2002011129A1 NL 0100582 W NL0100582 W NL 0100582W WO 0211129 A1 WO0211129 A1 WO 0211129A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- frequency
- current signal
- writing
- low
- signal
- Prior art date
Links
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
-
- 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
- G11B5/008—Recording on, or reproducing or erasing from, magnetic tapes, sheets, e.g. cards, or wires
- G11B5/00813—Recording on, or reproducing or erasing from, magnetic tapes, sheets, e.g. cards, or wires magnetic tapes
-
- 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
- G11B5/48—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed
- G11B5/58—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
- G11B5/584—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following for track following on tapes
Definitions
- the present invention relates to a method for writing information into a magnetic tape at different depth.
- servo signals with a relatively long wavelength are written "deeply" into a magnetic tape. "Deeply” is understood to mean here deeply with respect to data signals which are written into the tape at a relatively short wavelength. After writing or overwriting data signals the servo signals must remain intact as properly as possible. Since signals with a relatively long wavelength can be written more deeply into a magnetic carrier, this is generally successful. Only in the top layer of the magnetic carrier will servo signals be overwritten by data signals. The servo signals are therefore weakened by some db's.
- pulse width recording will also be understood to mean pulse position recording; for a pulse position modulated signal can be regarded as the first derivative of a pulse width modulated signal.
- bias recording the field can penetrate more deeply into the magnetic tape than in the other methods.
- Bias recording is used in practically all analogous recorders, while pulse width and therefore also pulse position recording are hardly used, if used at all.
- the object of the invention therefore generally is to provide a method for writing information at different depth, which information is particularly suitable for relatively narrow servo tracks, and which method can be particularly used for the deep writing of servo information.
- the method as described in the opening paragraph is characterized in that this writing current signal is composed of a first low-frequency writing current signal and a high-frequency writing current signal which is pulse width modulated by means of a second low- frequency writing current signal.
- the first and the second low-frequency writing current signal form a similar low-frequency writing current signal
- the pulse width modulation is such that the low-frequency component in the pulse width modulated signal is in opposite phase with the latter low-frequency writing current signal, and the magnetization in the top layer of the magnetic tape through the pulse width modulated current signal is opposed to the magnetization through the latter low-frequency writing current signal.
- the latter low-frequency writing current signal can be a servo current signal for the purpose of following tracks through a magnetic reading head and/or reading-writing head, while the high-frequency current signal is a data signal or a bias current signal for the purpose of writing servo signals.
- the invention further relates to a device in which the above method can be used.
- this device is provided with a first and a second low-frequency writing current generator and a high-frequency writing current generator, and with a modulator for pulse width modulating the frequency of a high-frequency writing current signal produced by the high- frequency writing current generator with a low-frequency signal continuously produced by the second low -frequency writing current generator, while, furthermore, a writing current combination element is present for combining the low-frequency writing current signal from the first low-frequency writing current generator and the high-frequency pulse width modulated writing current signal to the above writing current signal to be supplied to the magnetic writing head.
- the device is characterized in that it is provided with a low-frequency servo current generator and a high-frequency bias current generator, and with a modulator for pulse width modulating the frequency of a bias current signal produced by the bias current generator with a servo signal produced by the servo current generator, while, furthermore, a current combination element is present for combining the low-frequency servo current signal and the high- frequency pulse width modulated bias current signal to the above writing current signal to be supplied to the magnetic writing head, while through the modulated bias current signal a magnetization in the top layer of the magnetic tape can be effected, which is opposed to the magnetization through the servo current signal.
- the invention further relates to a recorder and/or reproduction device, provided with an arrangement as indicated above.
- Fig. 1 shows a number of diagrams in explanation of a known bias recording method
- Fig. 2 shows a number of diagrams in explanation of a known pulse width recording method
- Fig. 3 shows a simplified block diagram of a device according to the invention
- Fig. 4 shows a simplified block diagram of a device according to the invention, used for writing servo signals
- Fig. 5 shows a number of diagrams in explanation of the method according to the invention.
- the writing current signal for a magnetic writing head is formed by a combination of a low-frequency signal, such as, for instance, a low- frequency servo current signal, and a high-frequency bias current signal.
- a low-frequency signal such as, for instance, a low- frequency servo current signal
- a high-frequency bias current signal The amplitude of these signals is plotted in Fig. 1A and Fig. IB with respect to time.
- the bias frequency with respect to the frequency of the servo signal is shown relatively low.
- the bias frequency is often 500 to 1000 times as high as the frequency of the information to be written.
- the magnetization in a magnetic tape effected by the writing current signal is diagrammatically shown in Fig. 1C.
- the low-frequency information signal is written "deeply", while the high-frequency bias current signal only written into the top layer is such that when using a reading head with a relatively wide slit or a reading head of another type with high-frequency filtering, this signal is averaged completely.
- the bias current signal could only be read out when a reading head with a relatively narrow slit is used.
- pulse width modulation recording only a carrier is present, comparable with the bias frequency.
- the low ⁇ frequency information is written by modulating the duty cycle of the carrier with this low-frequency information.
- Fig. 2A the writing current signal belonging to this recording method is plotted with respect to time, while in Fig. 2B the thus effected magnetization in a magnetic tape is diagrammatically shown.
- the device used therefor is generally shown in Fig. 3.
- This device comprises a first low-frequency writing current generator 1, a second low- frequency writing current generator 2, a high-frequency writing current generator 3, a pulse width modulator 4, and a writing current combination element 5.
- the writing current signal S produced by the writing current combination element is composed of a low-frequency writing current signal SLFI originating from the first writing current generator 1 and a writing current signal SLF2 + SHF produced by the pulse width modulator, in which the signal SLF2 originates from the second low-frequency writing current generator 2 and the signal SHF originates from the high-frequency writing current generator 3.
- the signal SLFI will be written "deeply" into a magnetic tape, while the signal SLF2 + SHF will be written into the top layer of this magnetic tape.
- the two signals SLFI and SLF2 are simultaneously read out and, provided the frequencies of these signals are sufficiently different, filtered out and detected.
- This principle can in particular be applied to the writing of servo current signals while avoiding the above drawbacks attached to the above techniques individually.
- the device used therefor is shown in Fig. 4.
- This device differs from that of Fig. 3 at two points. First of all, instead of two low- frequency writing current generators only one is present here, namely the writing current generator 6. It produces a low-frequency writing current signal SLF, which is supplied both to the pulse width modulator 4 and directly to the writing current combination element 5.
- the writing current signal S produced by this combination element 5 is composed of a low-frequency writing current signal SLF and a pulse width modulated high-frequency signal SLF + SHF.
- SLF is a servo current signal SSERVO
- SLF + SHF is a pulse width modulated bias current signal SBIAS.
- the bias current signal is therefore written into the top layer of a magnetic tape, while the servo current signal is written more deeply.
- a reading head with a wide slit for reading out servo information only the servo information is read out, that is to say both the low-frequency servo signal and the low-frequency component of the pulse width modulated high-frequency bias current signal.
- the second point at which the device of Fig. 2 differs from that of Fig. 1 resides in an introduced phase difference of 180° between the above low -frequency servo signal and the low-frequency component in the pulse width modulated signal. This phase difference can be realized through inversion of the low- frequency servo signal supplied to the modulator 4 over the line 7 or in the modulator 4 itself.
- a magnetization in the top layer of the magnetic tape can be obtained, which is opposed to the magnetization through the servo current signal caused over a larger depth.
- the amplitude ratio between the two signals can be adjusted by regulating the bias writing current and the modulation depth.
- Fig. 5A shows the amplitude of a low-frequency servo signal with respect to time
- Fig. 5B shows the amplitude of a pulse width modulated of a bias current signal.
- the magnetization in a magnetic tape effected by the writing current signal is diagrammatically shown in Fig. 5 C.
- the pulse width modulated high-frequency bias signal is written into a top layer until a depth dl, and the low-frequency servo signal over the entire thickness of the tape layer shown.
- the low -frequency component of the pulse width modulated high-frequency basis signal is in opposite phase with the low-frequency servo signal written over the entire layer thickness.
- the resulting low-frequency servo signal is therefore weakened to a desired value.
Abstract
Description
Claims
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU2001286328A AU2001286328A1 (en) | 2000-07-28 | 2001-07-30 | Method for writing information into a magnetic tape at different depth |
EP01965760A EP1307878A1 (en) | 2000-07-28 | 2001-07-30 | Method for writing information into a magnetic tape at different depths |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
NL1015834A NL1015834C2 (en) | 2000-07-28 | 2000-07-28 | Method for writing information at different depths in a magnetic tape. |
NL1015834 | 2000-07-28 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2002011129A1 true WO2002011129A1 (en) | 2002-02-07 |
Family
ID=19771822
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/NL2001/000582 WO2002011129A1 (en) | 2000-07-28 | 2001-07-30 | Method for writing information into a magnetic tape at different depth |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP1307878A1 (en) |
AU (1) | AU2001286328A1 (en) |
NL (1) | NL1015834C2 (en) |
WO (1) | WO2002011129A1 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7382560B2 (en) * | 2003-04-29 | 2008-06-03 | Texas Instruments Incorporated | Low power servo mode write driver |
US8310780B2 (en) | 2010-07-20 | 2012-11-13 | International Business Machines Corporation | Method and apparatus for bipolar servo marks writing with high output |
Citations (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE917816C (en) * | 1951-07-21 | 1954-09-13 | Max Grundig | Method of recording magnetograms |
GB775050A (en) * | 1954-04-05 | 1957-05-15 | Philips Electrical Ind Ltd | Improvements in or relating to methods of recording signals |
GB897044A (en) * | 1959-07-13 | 1962-05-23 | Ampex | Improved magnetic recording system |
US4313140A (en) * | 1979-12-07 | 1982-01-26 | International Business Machines Corporation | Buried control signal recording systems and method |
US4314289A (en) * | 1979-12-07 | 1982-02-02 | International Business Machines Corporation | Biased pulsed recording systems and methods |
US4318141A (en) * | 1979-12-07 | 1982-03-02 | International Business Machines Corp. | Buried servo recording systems and methods |
JPS62298068A (en) * | 1986-06-16 | 1987-12-25 | Nec Corp | Magnetic disk |
JPH0432002A (en) * | 1990-05-28 | 1992-02-04 | Nec Corp | Magnetic disk |
US5319502A (en) * | 1992-01-10 | 1994-06-07 | International Business Machines Corporation | System and method for employing buried servos within a magnetic recording medium |
US5949607A (en) * | 1995-11-10 | 1999-09-07 | U.S. Philips Corporation | System, apparatus and method for recording and reproducing information |
-
2000
- 2000-07-28 NL NL1015834A patent/NL1015834C2/en not_active IP Right Cessation
-
2001
- 2001-07-30 WO PCT/NL2001/000582 patent/WO2002011129A1/en not_active Application Discontinuation
- 2001-07-30 EP EP01965760A patent/EP1307878A1/en not_active Withdrawn
- 2001-07-30 AU AU2001286328A patent/AU2001286328A1/en not_active Abandoned
Patent Citations (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE917816C (en) * | 1951-07-21 | 1954-09-13 | Max Grundig | Method of recording magnetograms |
GB775050A (en) * | 1954-04-05 | 1957-05-15 | Philips Electrical Ind Ltd | Improvements in or relating to methods of recording signals |
GB897044A (en) * | 1959-07-13 | 1962-05-23 | Ampex | Improved magnetic recording system |
US4313140A (en) * | 1979-12-07 | 1982-01-26 | International Business Machines Corporation | Buried control signal recording systems and method |
US4314289A (en) * | 1979-12-07 | 1982-02-02 | International Business Machines Corporation | Biased pulsed recording systems and methods |
US4318141A (en) * | 1979-12-07 | 1982-03-02 | International Business Machines Corp. | Buried servo recording systems and methods |
JPS62298068A (en) * | 1986-06-16 | 1987-12-25 | Nec Corp | Magnetic disk |
JPH0432002A (en) * | 1990-05-28 | 1992-02-04 | Nec Corp | Magnetic disk |
US5319502A (en) * | 1992-01-10 | 1994-06-07 | International Business Machines Corporation | System and method for employing buried servos within a magnetic recording medium |
US5949607A (en) * | 1995-11-10 | 1999-09-07 | U.S. Philips Corporation | System, apparatus and method for recording and reproducing information |
Non-Patent Citations (3)
Title |
---|
PATENT ABSTRACTS OF JAPAN vol. 012, no. 192 (P - 712) 4 June 1988 (1988-06-04) * |
PATENT ABSTRACTS OF JAPAN vol. 016, no. 201 (P - 1352) 14 May 1992 (1992-05-14) * |
T.A. SCHWARZ: "Recording Servo Information Below a Data Surface in a Homogeneous Medium. July 1974.", IBM TECHNICAL DISCLOSURE BULLETIN, vol. 17, no. 2, 1 July 1974 (1974-07-01), New York, US, pages 536 - 539, XP002163442 * |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7382560B2 (en) * | 2003-04-29 | 2008-06-03 | Texas Instruments Incorporated | Low power servo mode write driver |
US8310780B2 (en) | 2010-07-20 | 2012-11-13 | International Business Machines Corporation | Method and apparatus for bipolar servo marks writing with high output |
Also Published As
Publication number | Publication date |
---|---|
EP1307878A1 (en) | 2003-05-07 |
NL1015834C2 (en) | 2002-01-29 |
AU2001286328A1 (en) | 2002-02-13 |
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