JPS63161506A - Magnetic recording method - Google Patents

Abstract

PURPOSE:To eliminate deterioration of overwriting due to temperature by adjusting the recording current so as to cancel the change in the depth of recording depending on the difference between the temperature coefficient of a coercive force of a medium and the temperature coefficient of a saturated magnetic flux density. CONSTITUTION:A temperature sensor converts the temperature into an electrical signal and the recording current to cancel the difference of the temperature coefficient between a medium 1 and a head 2 is adjusted. The temperature change in the recording depth is decided by the difference (dHc/dT-dBs/dT) between the temperature coefficient (dHc/dT) of the coercive force and the temperature coefficient (dBs/dT) of the saturated magnetic flux density and since the recording depth is deepened by the positive combinations, in the case of the positive combinations of dHc/dT-dBs/dT, the recording current is increased as the temperature rise, and in the case of negative combinations, the recording is decreased so as to make the recording depth constant. Increase of the surface recording, the deterioration in the overwriting due to the change in the ambient temperature is suppressed to a small value.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention is applicable to flexible disks, hard disks, etc.
The present invention relates to a magnetic recording method that performs rewriting by overwriting.

(Conventional technology) FIG. 5 is a conceptual diagram of conventional overwriting.

By overwriting a new signal 4 on top of the signal 6 recorded on the medium 1 using the head 2, which has a gap length that allows recording to the bottom of the medium, the previous signal is simultaneously erased. be. Even if the size of the recording area 3 changes somewhat due to changes in temperature, etc., sufficient overwriting can be obtained since the recording area 3 reaches the bottom of the medium.

(Problems to be Solved by the Invention) The overwriting described above works well in devices with low recording density, that is, in devices where the head gap length is wide and saturation recording can be performed sufficiently to the bottom of the medium.

However, with the increase in recording density, heads with narrower gaps are being used. On the other hand, it is said that the maximum thickness of the media coating layer is about 0.711 m, and it is becoming difficult to uniformly coat the media below the thickness. Therefore, when recording with a narrow gap head, it is inevitable that the recording will be on the surface layer.

At this time, the problem is ensuring overwriting. If the coercive force of the medium is reduced to a certain extent, overwriting of about -28 dB can be ensured even in surface recording (Figure 6). However, if the coercive force of the medium or the saturation magnetic flux density of the head changes with temperature, the recording depth changes as shown in FIG. 7, leading to deterioration of overwriting due to unerased signals.

An object of the present invention is to eliminate such drawbacks and to provide a magnetic recording method in which overwriting does not deteriorate even if the operating temperature changes.

(Means for Solving the Problems) The magnetic recording method of the present invention is characterized in that the recording current is increased or decreased depending on the temperature so as to cancel out temperature changes in the magnetic properties of the medium and the head.

(Function) In the present invention, the recording current is increased or decreased so as to cancel out the change in recording depth caused by the temperature coefficient difference between the coercive force of the medium and the saturation magnetic flux density of the head. Light deterioration is extremely reduced.

(Example) Next, an example of the present invention will be described with reference to FIGS. 1 to 4.

FIG. 1 is a diagram showing the basic configuration of the present invention. A temperature sensor converts the temperature into an electrical signal, and the recording current is adjusted so as to cancel out the difference in temperature coefficient between the medium 1 and the head 2. A thermistor, thermocouple, or the like is suitable as the temperature detector. The direction and amount of adjustment of the recording current must be determined by the temperature coefficients of the medium and head. For example, a Ba ferrite medium has a positive temperature coefficient of coercive force (dHc/dT), and the coercive force increases as the temperature rises, whereas in other media such as yFe203, the coercive force decreases as the temperature rises. On the other hand, the temperature coefficient (dBs/dT) of the saturation magnetic flux density of a head material such as ferrite is negative, and the saturation magnetic flux density decreases as the temperature rises. The temperature change in the recording depth is determined by the difference between these temperature coefficients (dHc/dT - dBs/dT), and when this is a positive combination, the recording depth becomes deep. Therefore, in the case of a positive combination of dHc/dT - dBs/dT, the recording current may be increased as the temperature rises, and in the case of a negative combination, the recording current may be adjusted to decrease, thereby keeping the recording depth constant. If the recording current is to be increased at high temperatures, it can be easily achieved with a circuit as shown in FIG. This is because the recording current increases at high temperatures due to the temperature characteristics of VBE of the transistor 11. In this figure, 12 is an emitter resistor, 13 and 14 are base resistors, and 16 is an output transistor. FIG. 3 shows an embodiment using a temperature detection element 5 such as a thermistor.

If a semiconductor thermistor is used as the temperature detection element 15, the recording current will be small at high temperatures, and if a metal thermistor is used, the recording current will be large at high temperatures. Further, by moving the temperature detection element to the position of the resistor 12 or 14, the direction of increase and decrease of the current depending on the temperature can be reversed. The magnetic field created by the head is non-linear with respect to the current, so in order to compensate for this or change the amount of current correction depending on the type of medium, please use the Micro Table 1 Table 1 as shown in Figure 4. This is a summary of the effects of the present invention.

0/W25 is an overwrite value measured at a constant temperature of 25°C. 0/W10-5Q is written at 10°C and overwritten at 50°C, 0/W50-to is written at 50°C and overwritten at 10°.
This is an overwrite of double text in C. In each of the Examples, the deterioration of overwriting due to temperature changes was reduced to 1/10 or less compared to the Reference Example.

(Effects of the Invention) As described above, in the magnetic recording method of the present invention, even if surface recording is performed, deterioration in overwriting due to changes in ambient temperature can be suppressed to an extremely low level.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the basic configuration for implementing the method of the present invention, Fig. 2 is a diagram showing an embodiment using the temperature characteristics of a transistor, and Fig. 3 is a diagram showing an embodiment using a temperature detection element such as a thermistor. FIG. 4 is a diagram showing an example using a microbussor. FIG. 5 is a schematic diagram of a conventional overwrite. FIG. 6 is a conceptual diagram when the present invention is implemented. FIG. 7 is a conceptual diagram of a conventional head with a narrow gap. 1... Recording layer of medium, 2... Head, 3... Recording area, 4... New signal 5... Unerased signal, 6... Already recorded signal 11... - Constant current source transistor, 12... Emitter resistor 13... Base resistor, 14... Base resistor first
Figure 2 To the head Figure 3 To the head Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] A magnetic recording method characterized by changing a recording current according to temperature so as to offset temperature changes in overwrite characteristics caused by temperature changes in the medium, head, and magnetic characteristics.