JPH01128211A - Composite magnetic head - Google Patents

Abstract

PURPOSE:To obtain a composite magnetic head with less crosstalk and with satisfactory reproducing efficiency even if a space between both gaps is small by setting the magnetic permeability of a magnetic core between an R/W head gap and an erasing gap larger than that of a magnetic core on an outer side, where coil grooves are generated. CONSTITUTION:An R/W head 1 and an erasing head 2 have ferrite cores 3 and 7 with the winding grooves 14 and 15, where the effective permeability of use band is about 1,500, and the magnetic core 4 between the R/W gap 12 and the erasing gap 13 is set to an Mn-Zn ferrite with the effective permeability of about 2,000, whereby the space 16 between both gaps is set blow 200mum. With such construction, the composite head with less crosstalk and satisfactory reproducing efficiency by the R/W head can be obtained even if the space 16 between the head gaps becomes less than 200mum.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a magnetic head used for floppy disks and various magnetic tapes.

(Prior Art) With the recent increase in the amount of information, signal recording devices such as magnetic recording devices are required to have even higher recording densities. Many attempts have been made for this purpose. As a high-density recording method, perpendicular magnetic recording is considered to be one particularly promising method. Research and development for its practical application is being carried out vigorously. In this perpendicular magnetic recording method, it is necessary to minimize the spacing between the medium and the head. A device that can satisfy this requirement is a so-called floppy disk device.

On the other hand, the magnetic head used in floppy disk drives is
As recording density has improved, it has become necessary to reduce the distance between the R/W head and the erase head due to problems such as formatting capacity.

(Problems to be Solved by the Invention) However, in the conventional composite head, when this interval is reduced, crosstalk between the R/W head and the erase head increases. In order to avoid this, a non-magnetic material is interposed between the R/W head and the erase head to increase the magnetic resistance between the two heads and thereby reduce the amount of crosstalk. However, when this method is used, the recording/reproducing efficiency of the R/W head deteriorates, especially when the gap distance between both heads is 2.
When the diameter was less than 0.00 μm, the reproduction output was also small and there was a problem that the data signal could not be read correctly.

It is an object of the present invention to provide a composite magnetic head which has a small amount of crosstalk and has good reproduction efficiency of the R/W head even if the distance between the R/W rad gap and the erase rad gap becomes small. purpose.

[Structure of the invention]

(Problems to be solved) The present invention has the following features: 11. /W The above object is achieved by making the magnetic permeability of the magnetic core between the rad gap and the erase gap larger than the magnetic permeability of the outer magnetic core in which the coil groove is formed.

(Operation) Table 1 shows the calculation results of the amount of crosstalk using the finite element method, which does not provide a detailed explanation of the present invention.

The steps for calculating the amount of crosstalk are shown below.

(2) Place a permanent magnet near the R/W gap and count the number of lines of magnetic flux crossing the coil of the R/W head.

Next, place a permanent magnet near the erase gap, and
/W Count the number of magnetic flux lines that cross the head coil. The amount of crosstalk is determined by the number of lines of magnetic flux (■) - the number of lines of magnetic flux (■). The crosstalk is still assumed to be 201oy ((crosstalk amount)/number of magnetic flux lines) (dB).

The core permeability of the conventional composite magnetic head (Figure 6) is 15.
00, and the core magnetic permeability of the composite magnetic head of the present invention (FIG. 1) was set to 1500 and 4000. Also, for comparison, the shape is a three-piece type, and the magnetic permeability of both cores is 400.
I also calculated the value set to 0.

As shown in Table 1, it can be seen that the composite magnetic head of the present invention can simultaneously improve crosstalk and read efficiency of the R/W head.

The thickness of the magnetic core of the R/W head becomes smaller, and the R/W
The playback efficiency of the head also deteriorates significantly. In the present invention, R,/
By making the magnetic resistance of the magnetic core between the W gap and the erase gap smaller than the magnetic resistance of the core with the winding groove, the amount of crosstalk is reduced, so at the same time R, /
This has the advantage of increasing the reproduction efficiency of the W head.

(Margin below) (Example) An embodiment of the present invention will be described with reference to FIGS. 1 and 2.

FIGS. 1 and 2 show advance erase heads for floppy disks. In the figure, 1 is the R/W head;
2 is an erase head. Magnetic core with winding groove 3
, 7, the (effective) magnetic permeability of the used band is about 1500.
-Zn ferrite was used, and the effective magnetic permeability of the band used for the magnetic core 4 between the R/W gap and the erase gap was about 2000. At this time, set the distance between the R/W gap and the erase gap to 200μ.
I made it m. The R/W gap length and erase gap length are
0.35 μm each.

It is 2.0 μm. Further, the track width is 120 μm for the R/W head and 250 μm for the erase head. For comparison, a conventional composite magnetic head (FIG. 6) with a nonmagnetic spacer of 70 μm is used. The shape of this head has all the same dimensions except for the presence of a non-magnetic spacer. For the magnetic core in this case, Mn-Zn ferrite having a magnetic permeability of about 2000 in the band used was used.

Using these heads, Ba ferrite FD.

We also conducted recording and playback tests on metal FDs. At this time,
The R/W head is completely on track.

As a result, when the head of the present invention was used, the crosstalk was improved by 3 to 5 dB and the reproduction output of the R/W head was improved by 1 to 2 dB compared to the conventional head.

This eliminates the problem of not being able to read data correctly.

FIG. 3 shows another embodiment using the head of the present invention.

A tunnel erase type is used as the erase head. In this case, Mn-Zn ferrite with a magnetic permeability of about 1700 in the operating band is used for the magnetic core with the winding groove, and Mn-Zn ferrite with a magnetic permeability of about 2500 is used for the magnetic core between the R/W gap and the erase gap. ■-Zn ferrite was used. Further, the gap interval is set to 150 μm. R/
W gap length and erase gap length are each 0.3μ
m, 2.5 μm.

The magnetic permeability of the conventional magnetic head used for comparison is about 2000 in the band used. The shape and dimensions are all the same as the embodiment shown in FIG. 3, and the difference from the embodiment is that there is a 50 μm thick nonmagnetic spacer between the R/W gap and the erase gap.

Using both heads, Ba ferrite FD, Co-C
rFD.

Recording and reproducing tests were conducted on Co-γFD and metal FD.

As a result, when the head of the present invention was used, the crosstalk was improved by 2 to 3 dB and the reproduction output of the R/W head was improved by 1 to 2 dB compared to the conventional head.

In vertical media such as Ba ferrite) and Co-Cr media,
The higher the Bs force of the core with winding grooves is than that of the other core, the better the recording will be and the reproduction output will be improved, which is another advantage. This is because during recording, the central magnetic core with high magnetic permeability and small BS saturates earlier than the core with large Bs and low magnetic permeability, which has winding grooves, resulting in an asymmetrical magnetic field distribution and a ratio of the vertical component to p. This is because the in-plane component is larger than the in-plane component. Even when using a high Hc medium such as metal, it is not necessarily necessary to increase the Bs of both cores, but by increasing the Bs on the trailing edge side, that is, the Bs of the core on the winding groove side. Improved playback output.

The present invention is not limited to the embodiments described above,
Various modifications can be made without departing from the gist of the invention.

For example, as shown in FIG. 5, a core K with a winding groove
Even if a MiG type head sputtered with high Bs permalloy, Co-Zr amorphous, Sendust, etc., not only crosstalk but also reproduction output is improved. Further, the head shape is a five-piece type using a non-magnetic spacer similar to the conventional one, and the same effect can be obtained even if only the magnetic permeability of the magnetic core between the R/W gap and the erase gap is increased.

〔Effect of the invention〕

By making the magnetic permeability of the magnetic core sandwiched between the 几/W gap and the erase gap larger than the magnetic permeability of the magnetic core with winding grooves as in the present invention, it is possible to reduce the amount of crosstalk and at the same time have good reproduction efficiency. A composite magnetic head can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a composite head according to an embodiment of the present invention, FIG. 2 is a plan view of FIG. 1 viewed from the sliding surface side, and FIG. 3 is a composite head showing another embodiment of the present invention. 4 and 5 are a sectional view and a plan view of a composite head showing still another embodiment of the present invention, and FIG. 6 is a sectional view of a conventional magnetic head. It is a diagram. 1... R/W magnetic head, 2... Erase magnetic head. 3...First core half, 4...Second core half. 5... Non-magnetic spacer, 6... Second core half. 7...First core, 8...Magnetic coil. 9... Excitation coil, 10... Excitation coil. 11... Excitation coil, 12... (R/W) gap. 13... (erase) gap, 14... winding wire
groove. 15... Winding groove. 16... Distance between 几/W gap and erase gap. 17...Erase gap, 18...Metal magnetic layer. Agent Patent Attorney Nori Ken Yudo Matsuyama Light Speed Figure 1 Figure 2 Figure 3 Figure 4 Figure 1 Z Figure 6

Claims (5)

[Claims] (1) A first core half with a coil groove formed on its side surface, an excitation coil wound along the coil groove, and a glass, etc., connected to the side surface of the first core half on the coil groove side via a gap spacer. Using two magnetic heads consisting of second core halves joined by a joining material of
In a composite magnetic head in which core halves are joined via a non-magnetic spacer, the magnetic permeability of the second core half is the same as that of the first core half.
A composite magnetic head characterized by a magnetic permeability greater than that of the core. (2) A composite magnetic head according to claim 1, characterized in that the non-magnetic spacer is eliminated and two second cores are combined into one, thereby using three core halves. (3) A composite magnetic head according to claims 1 and 2, wherein Bs of the second core is smaller than Bs of the first core. (4) The composite magnetic head according to claim 1, wherein one of the two magnetic heads is a pre-erase head. (5) The composite magnetic head according to claim 1, wherein the gap distance between the two magnetic heads is 200 μm or less.