1. Field of the Invention
This invention relates to magnetic heads and, more particularly, to magnetic heads provided, in the magnetic recording medium sliding surface, with a first magnetic gap followed in the medium sliding direction by a second magnetic gap.
2. Description of the Related Art
Below, in this written specification, description is made by taking as the device of this kind an example of the so-called tunnel erase type magnetic head used in the apparatus for recording or reproducing digital signals on a disc-shaped magnetic recording medium.
FIGS. 1 and 3 are for explaining the structures of the cores of the different conventional tunnel erase type magnetic heads from each other, being top views schematically illustrating the magnetic recording medium sliding surfaces of the magnetic head cores. Also FIG. 2 and FIG. 4 are perspective views for explaining one step of the process for manufacturing the magnetic head cores of FIG. 1 and FIG. 3 respectively.
In FIG. 1, a recording-reproducing core 101 and erasing cores 102 and 103 each are made up of magnetic material such as ferrite, formed to a thin plate like shape and are provided respecitvely with a recording-reproducing gap 101g, and erasing gaps 102g and 103g. Also, spacers 104-106 are made up of non-magnetic material such as ceramic. This magnetic head core is constructed in such a way that, as shown in FIG. 2, a binding unit of the recording-reproducing core 101 and the spacer 104, another binding unit of the erasing core 102 and the spacer 105, and a further binding unit of the erasing core 103 and the spacer 106, totaling three units, are brought into butting each other in the directions indicated by arrows 110a and 110b in the figure, and, after the positions of the gaps 101g, 102g and 103g have been adjusted in directions indicated by arrows 111a and 111b, the three binding units are then joined.
Also, FIG. 3 shows the medium sliding surface of the tunnel erase type magnetic head core of the so-called bulk type.
A recording-reproducing gap 112g is formed in a recording-reproducing core 112 and its track width is defined by glass grooves 113a and 113b formed on either side of it. Two erasing gaps 114g and 114g' are formed in an erasing core 114. The track widths and spacing are defined by glass grooves 114a, 114b and 114c formed on either side of the respective gaps 114g and 114g'. This magnetic head core is constructed in such a way that as shown in FIG. 4, a recording-reproducing core block 115 and an erasing core block 116 are made in separation from each other, brought into butting each other in a direction indicated by an arrow 119 in the figure, and, after adjustment has been made in a direction indicated by an arrow 20 in the figure in order to match the relative positions of the recording-reproducing gap of the core block 115 and the erasing gap of the core block 116, they are joined. After that, cutting is carried out along section lines 121, and the magnetic head core is obtained.
In the magnetic head core shown in FIG. 1, in the production process, cementing of the three core binding units as in the step shown in FIG. 2 is necessary, and it is not easy to accurately control the positional relationship between the gaps 101g, 102g and 103g by adjustment of the directions of the arrows 111a and 111b. Also, in the case when a narrower track is achieved in order to increase the density of record, because the structure becomes so that the individual thicknesses of the cores 101, 102 and 103 are equal to the respective individual track widths, it is required that each core 101-103 is made thinner. For this reason, in the production process, it becomes more difficult to treat each core 101-103, and there is a problem that the yield is deteriorated due to the cause such as cracks or breakage of the core.
Meanwhile, in the head core shown in FIG. 3, it is easy to make a narrower track. But, even in this head core, it is not easy to accurately determine the positional relationship of each gap in such a block state as in FIG. 4. Further, even in each block, the only avoidance on the production is the position error of the magnetic gap. Therefore, in the production process, the control for suppressing the position error in the block of each gap is necessary along with the position coincidence between the above-described blocks. This point is becoming an obstacle to reduction of the production cost.