JPS63173205A - Writing method for magnetic recording medium - Google Patents

Abstract

PURPOSE:To core with a signal which is recorded at a high speed and with high density by impressing a high voltage to a coil in an initial period, and subsequently, impressing a low voltage and controlling a recording current flowing to the coil, in each one cycle period of a current flowing to the coil of a magnetic head. CONSTITUTION:In an initial period of a current pulse, a high voltage +V1 is impressed to a coil 1, and after a current has reached a stationary value, a low voltage +V2 is impressed to the coil 1 by switching a terminal of a changeover switch 5. Even when an operation in terminals (a), (b) of a changeover switch 4 is an ideal square wave pulse, as for a current waveform in points (c), (d), its become a rounding shape by C, R and L components which the coil 1 has, and when a switching frequency of the changeover switch 4 becomes high, the case a rise period becomes longer than one pulse width is generated. Therefore, in order to shorten the rise period, a recording current is increased suddenly by impressing the high voltage +V1 to the coil in the rise period, and in other period, a constant recording current is allowed to flow to the coil 1 by impressing the low voltage +V2.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for recording signal information on a magnetic recording medium such as a magnetic tape or a magnetic disk. The present invention relates to a magnetic recording medium writing method that controls flowing current.

(Prior art) For example, as a method for writing digital signals onto a magnetic recording medium, a changeover switch is used to flow an alternating current into the coil of a magnetic head, and an alternating magnetic field generated by this current is used to convert the signal into a magnetic recording medium. There are known ways to do this.

(Problem to be Solved by the Invention) Incidentally, it is desirable that the waveform of the current flowing through the coil of the magnetic head during the above writing be a perfect square wave, but in reality, due to the time delay caused by the coil, the rise of the pulse has a delay time expressed by a predetermined time constant.

Therefore, when the frequency of the current switching is increased in response to demands for faster recording speed or higher recording density, there is a problem in that sufficient signal recording cannot be performed due to the delay in the rise of the current waveform.

The present invention has been made to solve the above problem, and when a square wave pulse current is passed through the coil of a magnetic head in order to record a signal on a magnetic recording medium, the rise time of this pulse current is reduced to improve the signal output. The object of the present invention is to provide a magnetic recording medium writing method that can cope with higher speed and higher density recording.

(Means for Solving the Problems) The magnetic recording medium writing method of the present invention applies a high voltage to the coil in the initial period during each cycle of a current with reversed polarity that is passed through the coil of the magnetic head. The recording current is applied to the coil, and then a low voltage is applied to the coil to control the recording current flowing through the coil.

Here, the above-mentioned "current with reversed polarity" is a current that can cause a coil to alternately generate magnetic fields in opposite directions.

Further, the above-mentioned "one cycle period" refers to one pulse width (unit: time) of the pulse current, and each cycle period does not necessarily have to be constant.

Further, the above-mentioned "initial period" refers to a period including at least a part of the rising period of the pulse current.

Furthermore, [high voltage j and "low voltage" do not necessarily represent absolute voltage values, but are intended to represent the relative relationship between the two voltage values. Note that "low voltage" generally refers to a voltage that allows a steady current to flow through the coil for generating a recording magnetic field.

Note that the method of the present invention does not only mean switching the voltage applied to the coil in two stages, but also means switching it in multiple stages or continuously.

(Effects of the Invention) According to the magnetic recording medium writing method of the present invention, in each cycle period of the pulse current flowing through the coil, the voltage applied to the coil is set to a high voltage in the initial period, and the value of the current flowing through the coil is increased. It is possible to cause the current to increase rapidly, and then reduce the voltage applied to the coil to a low voltage so that a constant value of current flows through the coil.

Therefore, the rise period of the pulse current waveform flowing through the coil can be shortened to bring it closer to an ideal square wave pulse, which is useful when increasing the switching frequency of the recording current in response to demands for faster and higher density signal recording. It is also possible to perform sufficient signal recording.

Additionally, when the current flowing through the coil reaches the current value for signal recording, this current value can be maintained, which prevents damage to the coil caused by excessive current flowing through the coil. .

Embodiment An embodiment of the magnetic recording medium writing method according to the present invention will be described below.

FIG. 1 is a schematic diagram illustrating the principle of a signal recording circuit used to implement the method of the invention.

In digital magnetic recording, currents in opposite directions are passed alternately through the coil 1 of a magnetic head, and information represented by a square wave signal is written onto a magnetic recording medium placed close to the coil 1. That is, the current flowing from the power source 2 through the coil 1 to the constant current circuit 3 changes its current path alternately in the C direction or the d direction in accordance with the terminal switching of the changeover switch 4. As a result, an alternating magnetic field for writing information is generated in the coil 1.

By the way, in the method of the present invention, in order to speed up the rise of the pulse waveform of the recording current flowing through the coil 1, a high voltage of 1 V1 is applied to the coil 1 during the initial period of the current pulse, and after the current reaches a steady value, a changeover switch is applied. By switching the terminal 5, a low voltage +2 is applied to the coil 1.

FIG. 2 is a time chart showing current waveforms in various parts of the circuit shown in FIG. Terminal a of selector switch 4
Even if the operation at the terminals is an ideal square wave pulse as shown in FIG.
, R, and L components, the current waveform at points C and d has a shape with a blunted rise. Therefore, when the switching frequency of the selector switch 4 becomes high, the rise period (period required for rise) tx may become longer than one pulse width t2, and information cannot be input or output properly. Therefore, in order to shorten the rising period t1, this rising period t
1, a high voltage +V1 is applied to the coil 1 to rapidly increase the recording current, and in other periods, a low voltage +V2 is applied to the coil 1 to cause a constant recording current to be applied to the coil 1. I try to let it flow. In addition, Figure 2 e
is a time chart showing the voltage value at point e in the circuit shown in FIG.

Next, with reference to FIG. 3, a signal recording circuit used when recording digital signals using the method according to the present invention will be explained.

When a write information pulse train representing incorrect information is sequentially input from the input section 8 to the edge detection circuit 6, the edge detection circuit 6 detects the rising edge of each information pulse, and the edge detection generated based on this detection is performed. The pulse is input to the one-shot multivibrator 7, and in this multivibrator 7, a voltage switching signal is created that remains at H level from the rising edge for a period corresponding to the rising period t1,
This voltage switching signal is input to the voltage switching section 5a.

This voltage switching section 5a consists of a transistor and a resistor, and a constant voltage power supply element V is provided on the collector side of this transistor.
1. Furthermore, the center tap of the coil 1a of the magnetic head is connected to the emitter side. On the other hand, the false information pulse train is generated by switching the switching transistors 4a and 4b ON and OFF.
The input is input to the NAND circuit 9.10 that controls the FF, so that when the pulse is input (when the H level is input), the transistor 4a is set to the ON state and the transistor 4b is set to the OFF state, and the pulse is set to the ON state and transistor 4b to the OFF state. When no signal is input (when L level is input), transistor 4a is set to OFF state, and transistor 4b is set to ON state. In addition, both switching transistors 4
A constant current source 3a is connected to the emitters of a and 4b. According to this device, the direction of the current flowing through the coil 1a is alternately set in the direction of the arrow f or the direction of the arrow 9 depending on the level state of the input pulse. Then, for a period corresponding to the rising period 11 from the time when the level state is switched, high voltage +■ is applied to the coil 1a according to the H level of the voltage switching signal.
1 is applied, and during other periods, a low voltage element V1-α (α>0) is applied to the coil 1a according to the L level of the voltage switching signal. As a result, the rising period t1 of the pulse waveform of the current flowing through the coil 1a is shortened, and after this current reaches a predetermined recording current value, this current value remains unchanged until the level state of the write information pulse train changes next. maintained.

Although the above embodiments apply the method of the present invention to digital signal recording, it may also be applied to various other types of signal recording.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram for explaining the principle of a signal recording circuit used to implement the magnetic recording medium writing method according to the present invention;
FIG. 2 is a time chart showing current waveforms at various parts of the circuit shown in FIG. 1, and FIG. 3 is a circuit diagram showing a specific example of the circuit shown in FIG. 1. 1.1a... Magnetic head coil 2.2a... Power supply 3, 3a... Constant current source 4... Changeover switches 4a, 4b... Switching transistor 5...
Selector switch 5a... Voltage switching section Fig. 2

Claims (1)

[Claims] A predetermined voltage is applied to a coil of a magnetic head to cause a current with reversed polarity to flow, and a magnetic field generated in response to the current generates a signal on a magnetic recording medium disposed close to the coil. A magnetic recording medium, characterized in that when recording information, the predetermined voltage is set to a high voltage during an initial period of one cycle period of the current, and then the predetermined voltage is set to a low voltage. How to include.