JPH0366722B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a magnetic head used for recording/reproducing in a magnetic disk device, and in particular, a magnetic head provided exclusively for the inner and outer circumferential portions of a magnetic disk. related to magnetic heads.

A magnetic disk device is one of the mass storage devices that constitute a computer system. This device can increase the storage capacity by increasing the diameter of the magnetic disk or by increasing the number of disks attached to the same rotating shaft, and is often used as a storage medium in large computer systems.

[Prior art and issues to be solved by the invention]

Concentric tracks centered around the rotation axis are set in the magnetic disk recording area, and magnetic recording is performed on each track with recording bits arranged circumferentially. Since the rotational speed of the disk is constant, the bit density becomes sparser toward the outer periphery, and the recorded wavelength becomes longer.

The gap in the core of the magnetic head (hereinafter abbreviated as gap) must be sufficiently narrow and have sufficient resolution for the shortest wavelength data to be recorded. In other words, it is necessary to satisfy this condition even for the innermost track of a magnetic disk, but if you try to cover the entire disk area with a single head with the gap length determined in this way, it is necessary to satisfy this condition for the track near the outermost track. Around this point, the gap length becomes too narrow relative to the recording wavelength.

If the gap length is too narrow, the magnetic recording medium cannot be sufficiently magnetized, which not only deteriorates the antecedent characteristics, but also makes the resolution too good for relatively sparse bit densities, making it difficult to write competitively with the signals being handled. Since the demodulation circuit system is no longer appropriate, bit errors will occur.

FIG. 1 is a diagram showing the magnetic recording surface of a magnetic disk divided into two parts, where 1 is the magnetic disk, 2 is an access arm, 2a and 2b are magnetic heads, 3 is an inner circumferential portion, and 4 is an outer circumferential portion. . It is clear from the figure that if the rotational speed of the magnetic disk is constant, the central angle per one recording bit 5 is the same inside and outside, and the length of one bit increases as the outer circumference approaches.

The object of the present invention is to improve the resolution of a magnetic head;
It is an object of the present invention to provide a magnetic head in which the difference between the inner circumferential portion and the outer circumferential portion in electromagnetic conversion characteristics such as antecedent characteristics is reduced as much as possible.

[Means to solve the problem]

In order to solve the above problem, the magnetic head of the present invention has dedicated magnetic heads for the inner circumference and the outer circumference, and the shortest recording wavelength λ of the magnetic recording area handled by each head and the magnetic head Assuming a constant η such that g = λ/η holds between the gap length g of the core, the constant η ₀ of the magnetic head in the inner circumference and the constant η〓 of the outer circumference are |η〓−η ₀ g〓 and g ₀ are set so as to satisfy the function |≦1.

[Effect]

For regions where the bit length is large, it is sufficient to increase the gap of the magnetic head, but this does not mean that it can be set arbitrarily. By varying the gap length while keeping the relationship between the shortest recording wavelength λ and the gap length g of the core of the magnetic head approximately constant as in the present invention, it is possible not only to avoid an excessive increase in resolution, but also to The readout output of the magnetic recording in the inner circumferential portion and the outer circumferential portion can be approximated by the highest frequency and the lowest frequency, and circuit correction for peak shift becomes easy.

Since it is appropriate to explain the functions and effects of the present invention based on actual conditions, the detailed explanation will be included in the description of the embodiments in the next section.

〔Example〕

FIG. 1 is a diagram showing a magnetic recording surface of a magnetic recording device according to an embodiment. In this disk device, the diameter of the innermost track of the inner circumference part 13 is 201 mm, the diameter of the outermost track is 265 mm, the diameter of the innermost track of the outer circumferential part is 275 mm, and the diameter of the outermost track is 339 mm. When this is used at a rotation speed of 3600 rpm and a frequency of 5 MHz, the bit length of the innermost track on the inner circumference is
8μm, the bit length of the innermost track on the outer periphery is
It becomes 10.8μm.

The gap length of the recording/reproducing magnetic head of the magnetic disk is set to 1.4 μm for the inner circumference and 1.9 μm for the outer circumference. In this case, the constant η is at the inner circumference.
5.71, and 5.68 at the outer periphery, and the two are almost similar.

FIGS. 3 and 4 show the frequency characteristics and antecedent characteristics of the magnetic disk device. First, the third
The diagram will be explained.

The figure shows the relationship between bit density and head output in a magnetic head with η set as described above, where the solid line 15 relates to the magnetic head at the inner circumference, and the broken line 17 relates to the same gap. This is relevant when a long head is used on the outer periphery. Further, a solid line 16 shows a case where a head with a defined gap length according to the present invention is used at the outer periphery.

Since the horizontal axis of the diagram is the number of bits per unit length, the range corresponding to the same highest and lowest frequencies is a wide area toward the right of the diagram at the inner periphery, while at the outer periphery. The area is closer to the left and has a narrower width. Therefore, the maximum output/minimum output ratio in the range indicated by the broken line 17 is smaller than the same ratio in the range indicated by the solid line 15.

However, by widening the gap length of the magnetic head on the outer periphery, the output of this magnetic head changes to the solid line 1.
6, the ratio of maximum output/minimum output in the range increases, and the solid line 1
The ratio is close to the maximum output/minimum output ratio in the frequency range in No. 5.

By approximating the frequency dependence of the output of each magnetic head in this way, it becomes easy to correct the signal position shift (peak shift) using a circuit.

Next, FIG. 4 will be explained. As is well known to those skilled in the art, the prior history characteristic can be regarded as indicating how much old data is attenuated when a track on which certain data is recorded is overwritten with different data, and naturally, this attenuation amount is The larger the value, the better.

The solid line 18 in the figure is the antecedent characteristic at the inner circumference, and the solid line 19 is the antecedent characteristic at the outer circumference according to the present invention.
Compared to the dashed line 20, which is the previous history characteristic when the head of the outer circumference is the same as the inner circumference, the solid line 19 indicates that the old data is more significantly attenuated. The unit of the horizontal axis in the figure is ampere-turn.

In implementing the present invention, it is desirable that the constant .eta. be equal for both magnetic heads; however, even if there is a slight deviation, the same effect can be obtained. In a normal magnetic head, the value of η is almost never set to less than 3, and when the η of the two magnetic heads are different, the allowable range can be considered to be approximately ±1.

〔effect〕

As explained above, the gap length of the magnetic head on the inner circumference and the gap length of the magnetic head on the outer circumference are expressed as η
By setting the data to be shared, the resolution characteristics and antecedent characteristics can be kept within a range that can be easily processed by the demodulation circuit, and a highly reliable magnetic disk device can be realized.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the magnetic recording surface divided into two parts of a magnetic disk, Fig. 2 is a diagram showing the magnetic recording surface of the magnetic recording device of the embodiment, and Fig. 3 is a diagram showing the bit density and head output in the embodiment. FIG. 4 is a diagram showing the antecedent characteristics in the embodiment, in which 1 is a magnetic disk, 2 is an access arm, 2 is a diagram showing the relationship between
a, 2b are magnetic heads, 3, 13 are inner peripheral parts, 4,
Reference numeral 14 indicates the outer circumference, 5 indicates recording bits, 15 to 17 indicate head output characteristic lines, and 16 to 18 indicate previous history characteristic lines.

Claims (1)

[Claims] 1. A magnetic recording area is provided on the surface of a disk that rotates around a central axis, and the inner and outer peripheries of the magnetic recording area are recorded/reproduced by separate magnetic heads. In the magnetic head used in the magnetic recording device configured, in the inner peripheral part of the magnetic recording area, the shortest recording wavelength λ〓 and the gap length g〓 of the core of the magnetic head
The relationship between the shortest recording wavelength λ ₀ and the gap length g ₀ of the core of the magnetic head at the outer periphery of the magnetic recording area is g ₀ = λ ₀ / 1. A magnetic head characterized in that the gap g and g ₀ of the core are set to satisfy the following relationship: |η〓−η ₀ |≦1 when η ₀ .