JPH07296385A - Recording method for mother magnetic recording medium - Google Patents

Abstract

PURPOSE:To stabilize the quality of copy magnetic recording medium regardless of fluctuation in the value of recording current at the time of recording on a mother magnetic recording medium or fluctuation in the strength of transfer bias field at the time of transfer. CONSTITUTION:In order to record information on a mother tape, the current flowing through a recording magnetic head is set as follows. At first, an optimal recording current Iorc is determined so that the level of reproduced output signal is maximized. In other words, information is recorded on the mother tape by altering the recording current sequentially and the level of reproduced output signal from the mother tape is measured in order to determine the optimal current Iorc for maximizing the level of reproduced output signal. A recording current is then set equal to the sum of the optimal recording current Iroc and a predetermined current alpha. Fluctuation in the level of reproduced output signal from a copy tape due to fluctuation in the recording current value at the time of recording of the mother tape or in the strength of transfer bias field at the time of transfer is suppressed by setting the recording current higher than the optimal recording current Iroc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mother magnetic recording by applying a transfer bias magnetic field with the magnetic surface of an information recorded mother magnetic recording medium in contact with the magnetic surface of an unrecorded copy magnetic recording medium. The present invention relates to a recording method for a mother magnetic recording medium, which is suitable for recording information on a mother magnetic recording medium in a magnetic field transfer system for transferring the recorded contents of the medium to a copy magnetic recording medium.

[0002]

2. Description of the Related Art Conventionally, information recorded on a mother tape is transferred to a copy tape by winding the mother tape and the copy tape on different reels and bringing them into contact with each other and applying a transfer bias magnetic field. A magnetic field transfer method is known.

FIG. 8A shows a schematic structure of a mirror mother VTR 100 for recording information on a mother tape MT. In the figure, 101S is a supply reel, 101T
Is a take-up side reel, and 102 is a recording magnetic head. Coil 10 wound around core 102a of magnetic head 102
A current corresponding to the recording signal S _REC is supplied to the amplifier 2b from the amplifier 103, whereby the recording signal S _REC is recorded as information on the mother tape MT. In addition, 104 is a tape guide arranged along the traveling path of the mother tape MT.

FIG. 8B shows a magnetic field transfer device 2 for transferring information recorded on a mother tape MT to a copy tape CT.
00 has a schematic configuration. In the figure, 201S
And 201T are a supply-side reel and a take-up-side reel on the mother tape MT side, respectively. 202S and 202T are a supply-side reel and a take-up-side reel on the copy tape CT side, respectively. Reference numeral 203 is a transfer bias magnetic field head for generating a transfer bias magnetic field. An alternating current corresponding to the oscillation signal of the oscillator 205 is supplied from the amplifier 204 to the magnetic field generating coil 203b wound around the core 203a of the bias magnetic field head 203, whereby the contact portion between the mother tape MT and the copy tape CT is contacted. Transfer bias magnetic field (AC magnetic field) is applied,
Information recorded on the mother tape MT is transferred to the copy tape CT. Reference numeral 206 is a tape guide arranged along the running path of the mother tape MT, and 207 is a tape guide arranged along the running path of the copy tape CT.

FIG. 8C shows a cassette loader 300 for winding the copy tape CT on which the information recorded on the mother tape MT is transferred into a cassette. In the figure, 301 is a reel, 302 is a cassette, and 303 is a tape guide arranged along the running path of the copy tape CT.

[0006]

FIG. 9 shows the relationship between the recording current Ir and the reproduction output signal Em of a general magnetic tape, that is, the recording current output characteristic. In head recording on a magnetic tape, there is an optimum recording current Iorc that maximizes the level of the reproduction output signal Em. Even if a current larger than this is applied to the coil of the recording head, the magnetization of the recorded magnetic tape forms a closed loop, resulting in a thickness loss during reproduction, and the level of the reproduction output signal Em decreases (Television Society, 1980). Vol. 34, No. 11, p. 1016 (See Principles of Magnetic Recording).

Conventionally, the above-mentioned mirror mother VTR100
Then, information is recorded on the mother tape MT by setting the optimum recording current Iorc at which the level of the reproduction output signal Em is maximized. Therefore, there is a problem in that the quality of the copy tape is not stable because the transfer characteristics of the copy tape vary greatly due to variations in the recording current value during recording of the mother tape MT and variations in the transfer bias magnetic field strength during transfer. This tendency becomes remarkable when the mother tape MT is a vapor deposition tape formed by vapor depositing a magnetic layer.

Therefore, the present invention is intended to stabilize the quality of the copy magnetic recording medium irrespective of variations in the recording current value during recording of the mother magnetic recording medium and variations in the transfer bias magnetic field strength during transfer. .

[0009]

The present invention is generated by a transfer bias magnetic field head in a state where the magnetic surface of an information recording mother magnetic recording medium and the magnetic surface of an unrecorded copy magnetic recording medium are in contact with each other. In the magnetic field transfer method of applying the transfer bias magnetic field to copy the recorded contents of the mother magnetic recording medium to the copy magnetic recording medium, the value of the recording current flowing through the coil of the recording magnetic head at the time of recording information on the mother magnetic recording medium is recorded as the mother magnetic recording. The level of the reproduction output signal of the medium is set higher than the maximum value. For example, the mother magnetic recording medium is a vapor-deposited magnetic recording medium formed by vapor-depositing a magnetic layer.

[0010]

In the present invention, the value of the recording current flowing through the coil of the recording magnetic head at the time of recording information on the mother magnetic recording medium, for example, the vapor-deposited magnetic recording medium, is set to a value higher than the value at which the level of the reproduction output signal of the mother magnetic recording medium becomes maximum. Since the setting is made large, it is possible to suppress the level change of the reproduction output signal of the copy magnetic recording medium due to the variation of the recording current value at the time of recording on the mother magnetic recording medium and the variation of the transfer bias magnetic field strength at the time of transfer, and the copy magnetic recording It is possible to stabilize the quality of the medium.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A recording method for a mother magnetic recording medium according to the present invention will be described below with reference to FIG. In this example, in the mirror mother VTR 100 as shown in FIG. 8A, the recording current supplied to the recording magnetic head 102 is set as follows, and information is recorded on the mother tape MT. The procedure for setting the recording current will be described below with reference to the flowchart in FIG.

First, in step ST1, the optimum recording current Iorc that maximizes the level of the reproduction output signal is determined. In this case, the recording current is sequentially changed by adjusting the gain of the amplifier 103, information is recorded on the mother tape MT, and the level of the reproduction output signal of the mother tape is measured, whereby the level of the reproduction output signal is maximized. Optimum current Iorc
To decide.

Then, in step ST2, the recording current is set so as to be equal to the optimum recording current Iorc plus the predetermined current α. For example, when the mother tape MT is a vapor deposition tape, the total thickness d of the magnetic layer and the recording wavelength λ
The recording current is set so that the recording current becomes higher than the optimum recording current Iorc by 0 to +3 dB when the relationship of λ <4 · d.

As described above, in this embodiment, since the recording current is set to be larger than the optimum recording current Iorc, the copy tape due to the variation of the recording current value at the time of recording of the mother tape MT and the variation of the transfer bias magnetic field strength at the time of transfer. CT
The level change of the reproduction output signal can be suppressed to a small level, and the quality of the copy tape CT can be stabilized. The reason will be described in detail below.

FIG. 2 shows the recording current Ir of the mother tape MT.
And the reproduction output signal Em. The mark “◯” indicates the reproduction output signal Em when the recording current is the optimum recording current Iorc, and the level thereof is maximum. "□"
The mark indicates the reproduction output signal Em when the recording current is made smaller than the optimum recording current Iorc by α, and the mark “Δ” is the reproduction output signal Em when the recording current is made larger than the optimum recording current Iorc by α. Is shown. Even if the recording current is smaller or larger than the optimum recording current Iorc, the level of the reproduction output signal Em decreases, but the larger the recording current, the smaller the decrease.

FIG. 3 shows the relationship between the transfer bias magnetic field Hb applied to the mother tape MT and the reproduction output signal Em. “○” mark, “Δ” mark, and “□” mark represent the case where the transfer bias magnetic fields 0, Hb1, Hb2, and Hb3 were applied to the mother tape MT recorded with the recording currents Iorc, Iorc + α, and Iorc−α, respectively. The reproduction output signal Em is shown. In this case, the level decreases more as the bias magnetic field strength increases. Then, when the bias magnetic field strength is Hb2 or more, the level of the reproduction output signal Em is reversed between the case of recording with the recording current Iorc + α and the case of recording with the optimum recording current Iorc. This is because when the recording current is increased, the recording magnetic field becomes stronger against the bias magnetic field and is less likely to be demagnetized. Figure 4
Is the recording current Ir of the mother tape MT and the reproduction output signal Em.
And the relationship (recording current dependency) with the bias magnetic field Hb as a parameter.

By the way, the reproduction output signal Ec of the copy tape CT is obtained by using the amount of transfer efficiency η as the mother tape M.
It is obtained from the reproduction output signal Em of T (IEEE Trans.Mag,
Sep.1971 DLATjaden Theory of Anhysteretuc Conta
See ct Duplication). That is, the mother tape MT
And the reproduction output signal Ec of the copy tape CT have a relationship of η = Ec / Em. FIG. 5 shows the relationship (bias magnetic field dependence) between the transfer bias magnetic field Hb and the transfer efficiency η.

FIG. 6 shows the recording current Ir and the copy tape CT.
Of the reproduction output signal Ec. "○" mark,
"△" mark and "□" mark are recording currents Iorc and Iorc, respectively.
Copy tape C when information is transferred from the mother tape MT recorded with + α, Iorc-α to the copy tape CT
The reproduction output signal Ec of T is shown. In this case, the transfer bias magnetic field Hb is shown as a parameter.

A problem in actual magnetic field transfer is a deviation from the set value of the transfer bias magnetic field and a deviation from the set value of the recording current when recording the mother tape MT. Now, set the transfer bias magnetic field Hb to a valid value Hb.
It is assumed that the magnetic field is applied between 2 and Hb3 under the condition that it is not outside this range. This kind of magnetic field variation is sufficiently realistic. In this state, copy tape C
The reproduction output signal Ec of T may be obtained by varying the values (shaded portions) between the curves of Hb2 and Hb3.

FIG. 7 is an enlarged view of the hatched portion of FIG. 6 for easy understanding. Here, the reproduction output signal Ec of the copy tape CT is determined depending on whether the recording current Ir during recording of the mother tape MT is set to Iorc (recording state a) or Iorc + α (recording state b). Think differently. Now, it is assumed that the recording current deviates from the set value by the same amount (ΔI).

At this time, the difference between the maximum value and the minimum value of the reproduction output signal Ec is examined. Recording state a
The variation of the reproduction output signal Ec is ΔEca, the recording state b
The variation of the reproduction output signal Ec at is ΔEcb. Clearly from the figure, ΔEca> ΔEcb, and by setting the recording current at the time of recording of the mother tape MT to be larger than the optimum recording current Iorc, the reproduction output signal of the copy tape CT against variations in recording current, transfer bias magnetic field, etc. The level change of Ec can be suppressed to be small, and the quality of the copy tape CT can be stabilized.

Although the above-mentioned embodiment shows an example in which the magnetic recording medium is a magnetic tape, the present invention can be similarly applied to the case where the magnetic recording medium is a magnetic disk such as a floppy disk. You can

[0023]

According to the present invention, the value of the recording current supplied to the coil of the recording magnetic head at the time of recording information on the mother magnetic recording medium, for example, the vapor-deposited magnetic recording medium, is set so that the level of the reproduction output signal of the mother magnetic recording medium is maximum. Therefore, it is possible to suppress the level change of the reproduction output signal of the copy magnetic recording medium due to the variation of the recording current value at the time of recording of the mother magnetic recording medium and the variation of the transfer bias magnetic field strength at the time of transfer, There is an effect that the quality of the copy magnetic recording medium can be stabilized.

[Brief description of drawings]

FIG. 1 is a flowchart showing a recording current setting procedure in an embodiment.

FIG. 2 is a diagram showing a relationship between a recording signal and a reproduction output signal (mother tape).

FIG. 3 is a diagram showing a relationship between a transfer bias magnetic field and a reproduction output signal (mother tape).

FIG. 4 is a diagram showing a relationship between a recording current and a reproduction output signal (mother tape).

FIG. 5 is a diagram showing a relationship between a transfer bias magnetic field and transfer efficiency.

FIG. 6 is a diagram showing a relationship between a recording current and a reproduction output signal (copy tape).

FIG. 7 is a diagram showing a relationship between a recording current and a reproduction output signal (copy tape).

FIG. 8 is a diagram showing a schematic configuration of a mirror mother VTR, a magnetic field transfer device, and a cassette loader.

FIG. 9 is a diagram showing a relationship between a recording current and a reproduction output signal.

[Explanation of symbols]

 100 mirror mother VTR 102 recording magnetic head 103, 204 amplifier 200 magnetic field transfer device 203 transfer bias magnetic field head 300 cassette loader

Claims (2)

[Claims] 1. A transfer bias magnetic field generated by a transfer bias magnetic field head is applied while the magnetic surface of a mother magnetic recording medium on which information is recorded and the magnetic surface of an unrecorded copy magnetic recording medium are in contact with each other. In the magnetic field transfer method for transferring the recorded contents of the mother magnetic recording medium to the copy magnetic recording medium, the value of the recording current supplied to the coil of the recording magnetic head at the time of recording information on the mother magnetic recording medium is the reproduction output of the mother magnetic recording medium. A recording method for a mother magnetic recording medium, wherein the signal level is set higher than a maximum value. 2. The recording method for a mother magnetic recording medium according to claim 1, wherein the mother magnetic recording medium is a vapor-deposited magnetic recording medium formed by vapor-depositing a magnetic layer.