JPS6059513A - thin film magnetic head - Google Patents

Abstract

PURPOSE:To increase the leakage of magnetic flux from both the end parts of core width to the outside and to improve off-track characteristics by forming areas of which gap length is wider than that of a center part on both the end parts of the core width. CONSTITUTION:In a thin film magnetic head consisting of a coil 1 formed by a conductive layer and upper and lower magnetic layers 2, 3, the gap length between the upper and lower magnetic layer 2, 3 is formed so as to be wider at both the end parts of the core width than that of the center part of the core width when observing the gap length from the head floating surface in the arrow R direction. Therefore, the leakage of the magnetic flux from both the ends of the core width to the outside can be increased, so that the time margin loss at off-track can be reduced without reducing the time margin at on-track.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a thin film magnetic head, and in particular to the structure of a thin film magnetic head with excellent off-track characteristics. [Prior Art and Problems] The thin film magnetic head of the prior art , the gap length between the upper magnetic layer and the lower magnetic layer is formed to be uniform and constant in the core width direction. For this reason, when the gap length is narrowed to achieve high-density recording, the leakage of magnetic flux from both ends in the core width direction to the outside decreases in proportion to the gap length, resulting in poor on-track characteristics. There is a drawback.

[Purpose of the invention]

In view of the problems of the prior art described above, the object of the present invention is to
To provide a thin film magnetic head in which leakage of magnetic flux from both ends to the outside is increased by widening the gap length at both ends in the width direction of the core compared to the center part, thereby improving off-track characteristics. is.

[Structure of the invention]

In order to achieve the above object, in the present invention, the gap length between the upper magnetic layer and the lower magnetic layer is formed to be wider at both ends in the core width direction than in the center part in the core width direction. There is provided a thin film magnetic head characterized by the following.

[Embodiments of the invention]

Before explaining the present invention in detail, the basic principle of the present invention will be explained.

One of the characteristics of a magnetic head is off-track characteristics. This off-track characteristic, as shown in Figure 1,
It is represented by a graph in which the horizontal axis represents the off-track amount (μm) and the vertical axis represents the time margin amount (ns). This graph writes information at the on-track position,
This is a plot of measured values of time merge 7-jk when the information is read with the magnetic head placed off-track at the position indicated on the horizontal axis. In FIG. 1, the off-track characteristics when the gap length is 0.5 μm are shown as A, and the off-track characteristics when the gap length is 0.8 μm are shown as B. As is clear from Figure 1, K
, the narrower the gap length, the larger the time margin amount.

However, if we focus on the amount of time margin loss due to off-track when the amount of time margin when on-track (off-track amount is O) is the standard, as shown in FIG. 2, when the gap length is 0. When the gap length is 8 μm, B is smaller than A when the gap length is 0.5 μm. This means that the wider the gap length, the wider the core width at both ends υ
This is because the leakage magnetic flux is large, so the timer non-loss amount with respect to the off-track amount is reduced.

The principle of the present invention is to reduce the time margin loss cover due to off-track areas by paying attention to the front-inside phenomenon and providing wide gap length regions at both ends of the core width. Although the above structure is impossible (or extremely difficult) to realize with a conventional monolithic magnetic head, it can be easily realized with a thin film magnetic head.

A thin film magnetic head as an embodiment of the present invention will be described below. FIGS. 3(A) and 3(B) are diagrams showing the general structure of a thin film magnetic head and its cross section. Figure 3 (A
), In (13), the element is a coil formed by four electric wires, two and three electric wires, and upper and lower magnetic layers. The part indicated by the arrow R in FIG. 3(A) is the part facing the recording medium, which is a view of the head air bearing surface of the thin-film magnetic head as an embodiment of the present invention (i.e., the part shown by the arrow R). 3 (a view seen from the direction of arrow R in FIG. 3(A)) is shown in FIG.

2 in FIG. 4 is the running direction of the 1:6 recording medium.

In the thin film magnetic head shown in FIG. 4, the gap length between the upper and lower magnetic layers 2 and 3 is made wider at both ends of the core width than at the center of the core width.

The dimensions shown in FIG. 4 are given by way of example only. In this example, the thickness of the magnetic layer is 2 μm, the core width is 30 μm, the center width is 26 mm, and the center gap length is 0.5 μm.
The off-track characteristics of the thin-film magnetic head shown in FIG. 4, each having an end width of 2 μm and an end gap length of 0.8 μm, are shown as C in FIG. In addition, in FIG. 5, the characteristics of the conventional magnetic head shown in A and H in FIG. 1 are shown by broken lines for comparison. As shown in Figure 5, simply increasing the gap length (including the center) has the effect of reducing the amount of time margin loss due to off-track, but increasing the gap length reduces the resolution. This effect has been offset by the decrease in on-track time margin. However, in the thin film magnetic head according to the present invention, only the gap length at both ends is widened while keeping the gap length at the center narrow.
The above effects are achieved without decreasing the amount of syn, so
A magnetic head that is resistant to off-track is realized.

〔Effect of the invention〕

According to the present invention, the leakage of magnetic flux outward from both ends of the core width can be increased, so that the time margin loss ft t-H for off-track can be reduced without reducing the amount of on-track time margin. It is possible to provide a thin film magnetic head made of

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the off-track characteristics of a conventional thin-film magnetic head. FIG. Figure 3 (A),
(B) is a diagram showing the general structure of a thin film magnetic head and its cross section; FIG. 4 is a diagram of a thin film magnetic head as an embodiment of the present invention viewed from the air bearing surface of the head; FIG. 5 is a diagram showing all the off-track characteristics of the thin film magnetic head of FIG. 4. FIG. (Symbol Touge, bright) 1: Coil, 2: Upper magnetic layer, 3: Lower magnetic layer. Patent applicant Fujitsu Ltd. Patent agent Akira Aoki Patent attorney Kazuyuki Nishidate Patent attorney 1) Yukio Patent attorney Akiyuki Yamaguchi (7) Figure 1 Figure 2 Figure 3 (A) Figure 4 Figure 5 Off-track amount (pm)

Claims (1)

[Claims] 1. A thin film magnetic head, characterized in that a gap length between an upper magnetic layer and a lower magnetic layer is formed to be wider at both ends in the width direction of the core than at the center in the width direction of the core.