This invention relates to a thin film magnetic head used in a magnetic recording/reproduction device such as a video tape recorder.
A thin film magnetic head is constructed by superposing a magnetic thin film constituting a lower core, a gap film, a coil film, and a magnetic thin film constituting an upper core one after another on a non-magnetic substrate. These magnetic thin films are so formed that its thickness is generally smaller than 5 .mu.m. In such a magnetic thin film, when it is tried to record/reproduce e.g. video signals on/from a magnetic tape, taking its recording ability into account, it is necessary to set its gap depth so as to be smaller than 3 .mu.m.
However, a thin film magnetic head having such a small gap depth gives rise to a problem that its durability against abrasion is small because of its gap depth which is as small as 3 .mu.m when the magnetic head is intended for the so-called contact operation in which the magnetic head is brought into contact with a recording medium such as in a VTR, etc., although no problem arises when the magnetic head is intended for the so-called floating operation in which a certain space is maintained between the recording medium and the magnetic head such as when a hard disc is used for the recording medium.
Therefore it has been proposed e.g. in U.S. Pat. No. 4,219,855 to construct the magnetic head so that magnetic flux is concentrated towards the gap of the core by forming the thin film magnetic core so as to become wider gradually backward from the position 0 of the gap depth.
However, even in a thin film magnetic head constructed in such a manner, it is not possible to obtain a satisfactory effect to concentrate magnetic flux at the neighborhood of the gap. This is due to the fact that the effect to concentrate magnetic flux stated above is weakened by leakage of magnetic flux between the upper and the lower core at the portion near the position 0 of the gap depth and thus the magnetic flux at the gap, i.e. magnetic flux supplied to the recording medium is reduced. Consequently it is not possible to increase the durability against abrasion by enlarging the size of the gap depth.
USPTO Backgrounds
USPTO Backgrounds