JPS6012687B2 - Manufacturing method of multi-element magnetic head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention also relates to a magnetic head mounted on a magnetic disk device and a magnetic drum device used as an external storage device of a computer.

In recent years, in order to improve the performance of electronic computers, there has been a strong desire to shorten the access time in a head-per-track recording device in which a head 2 is attached to each track 1 as shown in FIG.

One way to achieve this is to increase the rotational speed of the media, but as the rotational speed increases, there are problems such as increased vibration and temperature rise due to increased heat generation, which significantly reduces the reliability of the device. is emerging as a major technical difficulty. Furthermore, the information transfer speed becomes faster, requiring significant improvements in circuit characteristics. For this reason, although it is possible to increase the rotation speed to a certain extent, it is difficult to dramatically increase the access time. As an alternative to this, there is the idea of a multi-head part rack system, and there are actually products that use this system. The multi-head per track system refers to a system in which a plurality of heads 2 (n) are attached to LI tracks 1, as shown in FIG. According to this, the access time can be set to 1 n of the conventional head per track without changing the rotation speed. However, despite the above-mentioned advantages, the head has manufacturing difficulties as described below, and the multi-head part-track type device tends to be expensive.
FIG. 3 shows the head floating on the drum device.

A core block 3 having a recording/reproducing core is attached to a load spring 4 and floats on a drum 5 with a floating gap of usually 1 to 2 feet. FIG. 4 depicts core block 3.
Although the core block 3 shown in the figure is a two-channel head, the number of channels can be any number greater than two. Each channel is separated by a groove 6 to form a core 7 around which a coil 8 is wound. The wings 9 on both sides are sliders with air bearing surfaces to provide flying force to the head.
A diamond cutter is used to process the groove 6,
Regarding the dimensional accuracy, when looking at the track pitch of 10, ±30 peaks is close to the limit accuracy on an industrial basis. Also, even if there are 11 tracks, there will inevitably be variations of ±20 peaks. 1
When using a head-per-track, these do not pose any problem, but when this core block 3 is used in a multi-head-per-track, some tracks become noise portions called off-tracks, and the SN ratio of the head drops significantly.

Off-track formation will be explained below. For simplicity, it is assumed that two channel heads constitute a two-head part track as shown in FIG.
Assume that all 11 of the tracks 3 are the same, but the track pitch 9 is deviated from the specified value for the a head 12 and the specified value for the b head 13 by ten ΔP. Assuming that this head constitutes two tracks as shown in Fig. 6, there are two tracks, A track 14 and B track 15, but in A track 14, the core 7 of both heads is completely Assume that they match. Therefore, even if both heads perform recording and reproduction on the A track 14, recording and reproduction can be performed smoothly as if only one head were performing the recording and reproduction. However, when considering the B track 15, in the worst case, the a head 12
After that, the b head 13 writes at the highest frequency used (
When writing is performed with fMx), a signal track 16 of fMx and an off-track 17 of fmin, which is a noise component, are generated on the B track 15 as shown in FIG. When this is reproduced by the a head 12, the reproduction voltage is 18,
Since it is proportional to 19, the S/N ratio is calculated and sM=spirit=
T-band PX professional cattle electrification (fmax) Constant resolution = reproduction voltage (fmin) Tw: Track pitch △P: Track pitch deviation Here, the head used by the inventor in the test is △P = 30 French, T
w=200 French, resolution 0.

5, but by the way, if you substitute these into the above equation, the S/N ratio will only reach 3rd place.

In order to perform highly reliable reading with a normal circuit, an S/N ratio of 5 or more is required, so the above value of 3 is a very low value. The only option is to further increase the pitch accuracy, further widen the Tw in the track, or raise the disassembly.If there is variation in the Tw in the track, the situation will worsen.In any case, the price is high. There are many aspects that make it unsuitable for use on an industrial basis.
This is especially true if it becomes a multi-head par track with three heads or more. These problems have been difficult to manufacture when manufacturing a head for a conventional multi-track per head type device. An object of the present invention is to provide a method for easily and inexpensively manufacturing multi-element magnetic heads of the same size.

A feature of the present invention is that a rectangular magnetic block is joined to the grooved surface of a magnetic block having a plurality of grooves, and the rectangular magnetic block is joined from the side of the magnetic block having the grooves. A plurality of core elements are formed by making cuts so as to bite into the rectangular magnetic block,
By cutting between the grooves, a multi-element magnetic head having a plurality of core elements using a rectangular magnetic block as a common magnetic circuit is manufactured at once.

An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 8 to FIG. 11 are diagrams showing the core manufacturing method according to the present invention.

For simplicity, a diagram for making two heads for a two-head part track is shown. First, form two core blocks like 20 and 21 (Fig. 8), then use adhesive such as glass to form 2 core blocks.
The two blocks are joined to form one core block 22 (FIG. 9).

The core block 22 produced in this way is grooved with a diamond cutter (Fig. 10), and after machining, the core block 2
2 into two parts (Figure 11). Thus obtained 2
Recording and reproducing surface sides 25 and 2 of the two core clones 23 and 24
6 is made into a mirror surface by wrapping or the like, and two heads are completed at the same time. According to this manufacturing method, since the grooves are processed in exactly the same manner in the two heads, the track pitch and the track length are naturally the same.

Therefore, it is possible to prevent the deterioration of the SN ratio due to off-track as described above, and when this head is mounted on the same track, highly reliable recording and reproduction is possible even on a two-head par track. This manufacturing method is effective even when the number of heads is 3 or more heads.

As an example, FIG. 12 depicts a core block 27 for a four-head track. If this is separated into four parts, four identical heads can be made, and a head for a four-head part track can be obtained. As can be seen from the above, by employing the present invention, a multi-element magnetic head used in a multi-head-per-track type magnetic storage device can be obtained at low cost and as a head with a good signal-to-noise ratio.

[Brief explanation of the drawing]

Figure 1 shows the principle of a conventional head-per-track storage device, Figure 2 shows the principle of a multi-head-per-track storage device, and Figure 3 shows a situation where the head is floating above the drum. FIG. 4 is a diagram explaining a conventional monolithic type multi-element magnetic head. FIGS. 5 and 6 are diagrams explaining heads and tracks that constitute a two-head-per-track. FIG. 7 is a diagram explaining a conventional monolithic type multi-element magnetic head. Figures 8 to 11 are diagrams illustrating the deterioration of the SN ratio due to the track.
The figure shows a method of manufacturing a core for a 4-head part truck. 20-24... core block, 25, 26... recording/reproducing surface, 27... core block. Oh Prisoner 2 Evil Person 3 Illustration Person 4 Illustration Person 5 Illustration Person 0 Evil Person 7 Illustration Person 8 Illustration Nao Illustration Person'0 Illustration Person'i Illustration Person'2 Crab

Claims (1)

[Claims] 1. A rectangular magnetic block is joined to the grooved surface of a magnetic block having a plurality of grooves, and the rectangular magnetic block is bonded from the side of the magnetic block having the grooves toward the rectangular magnetic block. A multi-element magnetic head having a plurality of core elements with a rectangular magnetic block as a common magnetic circuit can be produced by making cuts to cut into the grooves to form a plurality of core elements and cutting between the grooves. A method for manufacturing a multi-element magnetic head characterized by batch manufacturing.