JPS62107409A - Vertical magnetic recording device - Google Patents

Abstract

PURPOSE:To obtain an excellent recording and reproducing characteristic by selecting the relation among the saturated magnetic flux density of a head, gap, vertical coercive force of a recording layer of a medium and film thickness as a specified condition so as to select the coercive force and the film thickness of the medium in the range that the amplitude of the reproduced output at the head over-saturation is constant independently of the recording density. CONSTITUTION:A ring type head and a recording medium having an easy magnetization axis perpendicularly to a medium face are used for a vertical magnetic recording device. The saturated magnetic flux density Bs1 of the magnetic head, the gap (gl), the coercive force HCL of the recording layer of the recording medium and the film thickness tmas are selected to satisfy the equation of tmas(mum)XHCL(koe)<=[0.03Xgl(mum)XBs(KG)]<0.65>. Then the coercive force HCL of the recording layer of the recording medium and the film thickness tmas are selected in a range so that the reproduced output amplitude at the over- saturation of the head is constant independently of the recording density to provide an excellent recording/reproducing characteristic to the recording device.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a perpendicular magnetic recording device using a ring-shaped head and a recording medium having perpendicular anisotropy, and particularly to a floppy device with suitable recording and reproducing characteristics.

[Background of the invention]

In conventional ring head recording/reproduction, recording/reproduction is performed with less magnetomotive force than the start of head saturation, and the present invention relates to a recording method unique to ring heads/perpendicular media. I don't see it.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a perpendicular magnetic device that realizes high-density recording and reproduction and that does not cause fluctuations in reproduction output amplitude in response to fluctuations in recording current.

[Summary of the invention]

It has been experimentally confirmed that the conditions under which saturation recording can be performed at zero in a device using a ring-type head and a recording medium having perpendicular anisotropy are given by the following equation in the case of a floppy device.

t, aII (μlI) × HcI, (KO-)≦(0,0
3X g Q (μm) This has made it possible to provide a perpendicular magnetic recording device that can achieve the above objectives.

[Embodiments of the invention]

An embodiment of the present invention will be described below. FIG. 1 shows the configuration of the head medium system used in this embodiment. The head is M n
The head ring was made by sputtering Zn ferrite or a high BS material in the gap, and the medium was made by sputtering a Co--Cr layer on the film base. Head saturation magnetic flux density BS, gap length g
FIG. 2 shows the results of determining the saturation recording limit curve using Ω, the perpendicular coercive force HCL of the medium, and the film thickness j m&l as parameters.

From this figure, it was found that the following equation holds true as a condition for saturation recording.

tmag(μm)XHct, (Kos)≦(0,03X
gQ(μm)XBs(Ko))'=IS...(1) Therefore, for example, gQ=0.30μm, Bs=5000G
When using auss M n Z n ferrite ring head teat (μm) XHcL (xoe) ≦ 0.133 (
μm・goa) −(2). Figure 3 shows the results of numerical analysis of the relationship between the gradient aHy/ax of the head magnetic field in the direction of the ice surface and the magnetomotive force of the head using the vertical head magnetic field strength Hy as a parameter when using the above M n Z n ferrite ring head. Shown below. From this figure) 1 y = 7000 e or more, a Hy / a x becomes constant at a magnetomotive force above the head saturation starting point. This is because, in the case of the above M n Z n ferrite ring head, the magnetic field distribution with a magnetic field strength of 7000e or more does not change with a magnetomotive force above the head saturation starting point, and the perpendicular coercive force Hct of the medium, ≧ 7000
This means that when recording and reproducing a medium with the above head, the recording state on the medium will not change if the magnetomotive force exceeds the head saturation starting point. Therefore, the experimental formula for the saturation recording conditions obtained from the experimental results shown in Figure 2 (%) is the medium condition Hc+ obtained from the head magnetic field analysis results
, ≧70006, as shown in FIG.
The thickness of the Cr layer needs to be 0.18 μm or less.

In Figure 5, g n =0.30 pm, Bs = 500
0 Gauss M n Z n ferrite head, H
ct, ≧7000e.

This is a recording current characteristic when recording and reproducing is performed on a Co--Cr medium with t+mag = 0.18 pm. From this figure, when recording and reproducing are performed with a magnetomotive force equal to or higher than the head saturation starting point, the reproducing output is constant regardless of the recording density. Therefore, if recording and reproduction is performed with a magnetomotive force greater than the head saturation starting point,
It is possible to provide an apparatus in which the recording and reproducing characteristics do not change with respect to changes in magnetomotive force.

〔Effect of the invention〕

According to the present invention, the HCL and teas of the medium can be defined in accordance with the Bs and SQ of the head so as to obtain stable reproduction output against fluctuations in magnetomotive force within the range that allows saturation recording, and the BS and gQ of the head Since the optimum recording medium can be selected depending on the situation, there is an effect that good recording and reproducing characteristics can be obtained.

[Brief explanation of drawings]

Figure 1 is a sectional view of the head medium system, Figure 2 is gfiX
Experimental results showing the relationship between Bs and t mJlf
Bg==5000 Gauss head magnetomotive force and aHy
/ax relationship, Figure 4 shows HCL in the saturation recordable range.
A diagram showing the conditions for determining Itaag, and FIG. 5 shows the recording current characteristics of the head medium used in this example. 1... Head core, 2... Coil, 3... Go
-Cr layer, 4... base film,
-・51, Agent Patent Attorney Katsuma Ogawa
) Figure 2, No. 3? Power to running 3 stones (HaT) No. 40 tpprau (5th item on the right

Claims (1)

[Claims] 1. In a perpendicular magnetic recording device having a ring-shaped head and a recording medium having an axis of easy magnetization perpendicular to the medium surface, the saturation magnetic flux density B_S gap length gl of the head and the perpendicular coercive force of the recording layer of the medium H_C_L, film thickness t
Regarding _m_a_g, t_m_a_g (μm)×H_
C_L(_K_O_e)≦(0.03×gl(μm)×
B_s(_K_G))^0^. ＾6＾5 conditions are satisfied,
H_C_L, t_m_a_
A perpendicular magnetic recording device characterized in that g is selected.