JPS58208919A - Magnetic head - Google Patents

Abstract

PURPOSE:To raise the level of a reproducing output signal, and to prevent a noise signal from being mixed, by providing a magnetoresistance effect element for converting the magnetic recording on a magnetic recording medium to an electric signal, on the main magnetic pole, in a magnetic head of a vertical magnetic recording and reproducing type. CONSTITUTION:A head which forms a main magnetic pole 1 and a magnetoresistance effect element (MR element) 27 on one side and the other face of a substrate 26, respectively, and has a distance (h) from the end face of the substrate 26 is provided with respect to an auxiliary magnetic pole 2 of a recording and reproducing magnetic head of a vertical magnetic recording medium 4. The distance (h) is set to about 10-30mu so that abrasion due to contact with the recording medium of the element 27 is prevented. In order to fetch and amplify a signal of the MR element 27, an integrated circuit chip 28 is fitted to the face on which the element 27 of the substrate 26 is formed, and it is connected to the element 27 by a lead wire 29. In this way, a noise is prevented. In this regard, a capacitor 29, etc. are provided on the substrate 26. In this way, the reproducing output signal level is made higher than that of a conventional head, and it is prevented that a malfunction occurs due to mixing of a noise, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic head, and more particularly to a magnetic head that performs perpendicular magnetic recording and reproduction.

The principle of perpendicular magnetic recording is as shown in FIG.

In the figure, reference numeral 1 indicates the main pole, which is made of a Ni--Fe alloy with a thickness of about 1 to 2 Bm. This main magnetic pole l and about 80gmj
The auxiliary magnetic pole 2 is placed at the opposite position. This auxiliary magnetic pole 2 is a rod-shaped ferrite (Mn
-Zn), etc., and a recording coil 3 is wound around its outer peripheral surface, for example, 100 times. A magnetic recording medium 4, typically a floppy disk, is run between the main magnetic pole 1 and the auxiliary magnetic pole 2. This magnetic recording medium 4 has a base 4a made of a polyester film with a thickness of about 50 gm, and a zero for non-recording on the side surface of the main magnetic pole 1 side.
．． A Ni--Fe layer 4b having a thickness of about 5 gm is deposited, and a Co--Cr layer 4C having a thickness of about 0.5 gm for recording is further deposited thereon.

The Ni--Fe layer 4b is a high magnetic permeability material and has the role of reducing magnetic resistance and allowing magnetic flux to concentrate on the main pole.

When a pulse current is applied to the coil 3 in this structure, lines of magnetic force are generated from the auxiliary magnetic pole 2 toward the main magnetic pole 1. As shown by the dotted arrow in FIG. 1, these lines of magnetic force first travel almost straight toward the Ni-Fe layer 4b with high magnetic permeability, and when they hit this layer 4b, the lines of magnetic force run in the in-plane direction, causing C
Within the o-, Cr layer 4C, lines of magnetic force run perpendicularly toward the main magnetic pole l, magnetizing this layer 4C and performing magnetic recording.

When such a perpendicular magnetic recording method is adopted, much higher density recording is possible than with conventional ring-shaped magnetic heads, which perform magnetic recording in the in-plane direction.

For example, the recording density for a floppy disk using a ring-type magnetic head currently on the market is IOK b
ITS/1nch (approximately 25mm) is the limit, but if perpendicular magnetic recording is adopted, the
Recording of 00K bits/1nch is possible.

However, even if magnetic recording of around 100K bits/1 nch is possible, reproduction is difficult. As the current perpendicular magnetic recording and reproducing method, a method of detecting signals by winding a reproducing coil around the auxiliary magnetic pole is also being considered, but the distance between the recording layer (Ni-Fe layer) of the recording medium and the auxiliary magnetic pole is 50 g.
Due to the distance, the level of the reproduced output signal is low and noise is mixed in, which is disadvantageous in that malfunctions are likely to occur.

Such a perpendicular magnetic recording head is attached to a drive device as shown in FIG. 2, for example.

In FIG. 2, reference numeral 5 denotes a carriage, which is slidably attached along a guide shaft (not shown), and the above-mentioned auxiliary magnetic pole 2 is attached to the upper surface of one end of the carriage.

A helad arm 6 for the main magnetic pole is provided on the upper side of the carriage 5. A leaf spring 7 is fixed to the base end of the head arm 6, and this leaf spring 7 is attached to the carriage 5.
is fixed to the end opposite to the auxiliary magnetic pole 2 with a screw 9 via a backing plate 8. A main magnetic pole 1 is attached to the free end side of the head arm 6 at a position opposite to the auxiliary magnetic pole 2 on the ← plane.

A terminal plate 10 is provided on the upper surface of the head arm 6 opposite to the main magnetic pole 1, and a shield wire 12 having a length of, for example, about 100 to 200 mm is provided between the terminal plate 1o and the printed circuit board 11. It is connected. The reason why the shield wire 12 is used is to prevent noise from being picked up. Electronic components 1 such as LSI are on the printed circuit board ll side.
3 is installed.

In the middle of the helad arm 6, there is an L//<
A solenoid 14 is provided below the lever 6ac7) at a position where it engages with the lever 6ac7).
A force is applied by the leaf spring 7 in the direction in which the main magnetic pole 1 approaches the auxiliary magnetic pole 2, and the lower end of the pin 17 adjustable in the middle of the head arm 6 comes into contact with the protrusion 5a on the carriage 5 side. Its lower limit is regulated.

That is, when the solenoid 14 is not energized, the rod is in a free state and the movable piece 15 is moved upward via the spring 16, and the head arm 6 is pushed up via the lever 6a, causing the main magnetic pole 1 and the auxiliary magnetic pole 2 to move upward. There is an open space between.

Magnetic disk cassette 1 adopted this structure.
This is to prevent the main magnetic pole 1 from touching the magnetic disk cassette 1 when the magnetic disk cassette 8 is installed in the apparatus. and,
When the magnetic disk cassette 18 is installed and the device is in the driving state, the solenoid 14 is energized, the movable piece 15 is lowered, and the force of the leaf spring 7 moves the head arm 6. Therefore, the main magnetic pole 1 is lowered, and the magnetic disk 19 housed in the magnetic disk cassette 18 is sandwiched vertically through the opening 18a of the cassette to perform magnetic recording and reproduction. At this time, the distance between the auxiliary magnetic pole 2 and the main magnetic pole 1 is approximately 80ILm,
This distance is ensured by the lower end of the pin 17 hitting the protrusion 5a.

The magnetic disk 19 is rotated by fitting a boss 22a protruding from a pulley 22 rotated by a motor 20 through a belt 21 into a center hole lea of the disk.

The reference numeral 23 is a pulse motor, and its output shaft 23
Both ends of narrow steel belts 24 and 25 wound around a are fixed to the carriage 5, and the pulse motor 23
The carriage 5 moves in accordance with the control signal by winding and unwinding these steel belts 24, 25 in accordance with the rotation of the carriage 5.

The magnetic head used in the above-mentioned perpendicular magnetic recording device has a structure in which the main magnetic pole and the auxiliary magnetic pole form a pair as described above, and is suitable for high-speed magnetic recording, but as mentioned above, it is difficult to reproduce. It has the disadvantage that it is difficult and noise etc. are easily mixed in.

The present invention has been made in order to eliminate the above-mentioned conventional drawbacks, and an object of the present invention is to provide a perpendicular magnetic recording/reproducing type magnetic head configured to reliably perform perpendicular magnetic recording/reproducing.

In the present invention, in order to achieve the above object, a reproducing head is provided on the main pole side near the recording layer of the magnetic recording medium.
A structure including a magnetoresistive element (hereinafter referred to as MR element) for converting magnetic recording into an electric signal was adopted.

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 3 explains the basic structure of the present invention, and the same parts as in FIG. 1 are denoted by the same reference numerals, and the explanation thereof will be omitted.

In the present invention, the main magnetic pole 1 is formed on one side of the substrate 26 constituting the main magnetic pole head, and the M for reproduction is formed on the other side.
An R element 27 is formed. By doing this, the MR element 27 for reproduction is brought close to the recording surface of the magnetic recording medium 4, and weak magnetic changes can be picked up efficiently.

To explain in more detail, the structure is as shown in FIGS. 4 and 5.

That is, the main magnetic pole 1 formed on one side of a substrate 26 made of glass or the like is formed by depositing a Ni--Fe alloy, which is a high permeability magnetic material, to a thickness of about Igm.

Also, the MR element 27 is the same (made of Ni-Fe alloy with a thickness of 0.
It is formed by vapor deposition as a pattern bent in a zigzag manner at right angles so that the 051" Dr width is 5 to 108 Lfl+ and the developed effective length is 1 to 2 mm. The resistance value of the MR element 27 formed in this way is is approximately IKΩ, but changes to approximately 880Ω when a magnetic field is applied in a direction perpendicular to the pattern of the MR element 27 parallel to the end surface 2Eia of the substrate 26, as shown in FIG. 7(A).

That is, as shown in FIG. 6, the characteristics of the MR element 27 are such that its internal resistance value changes rapidly by several percent with a change in the magnetic field of 50 Oe. After that, even if the field is strengthened, it reaches a certain minimum value, but the resistance value hardly changes.

Since the MR element has such properties, its internal resistance can change by about 2% even when the magnetization of the recording medium 4 changes.

As shown in FIG. 7(B), the internal resistance of this MR element does not change even when a magnetic field is applied in the horizontal direction, and it is suitable for picking up changes in the magnetic field in the vertical direction.

Now, when a voltage of IV is applied across the internal resistance IKΩ of the MR element 27, a current of 1 mA flows through this resistance.

Therefore, if the resistance value changes by 20Ω due to a change in the magnetization of the recording medium 4, the voltage change will be 20ΩX O,
A voltage change of 001 A = 20 mV is obtained. This is the so-called magnetoresistive effect, and an element with such a function is an MR element.

In the above example, an MR element having an internal resistance of IKΩ is used, but an MR element having a higher or lower resistance value may be used.

By the way, both the main magnetic pole l and the reproduction MR element 27 have the same N.
If a magnetic field is generated due to the use of i-Fe alloy,
That is, during recording, magnetic flux flows into the main magnetic pole 1 made of a high permeability magnetic material and the MR element 27, causing a recording malfunction.

Therefore, in the present invention, the thickness of the MR element 27 is set to several tenths of the thickness of the main magnetic pole 1 to drastically reduce the magnetic flux flowing into the MR element and prevent recording malfunctions.

Specifically, as shown in FIG. 8, the thickness T of the main pole 1 was set to Igm, approximately ii0,05 gm on the MR element's side, so that no recording malfunction occurred.

In addition, since there is a distance h between one edge of the MR element and the end surface 26a of the substrate 26, which is the end surface of the main magnetic pole 1, the influence of the MR element on the main magnetic pole 1 is further reduced. If the value is increased, the distance from the recording surface of the recording medium 4 increases, and the magnetic recording cannot be picked up, resulting in a decrease in the output signal. Furthermore, if the dimension is made smaller, if the end surface of the substrate 26 is worn out due to contact with the recording medium, the MR element 27 will also come into direct contact with the recording medium, causing damage, so there is a limit to reducing the dimension h.

According to experiments, if the h dimension was 1O to 30ILm, no problems occurred in terms of signal level reduction, wear, or machining accuracy.

Even if DCIV is applied to both ends of the above-mentioned MR element, the voltage change is about 20 mV, so it is not suitable for the field of measuring the strength of a magnetic field. However, since a magnetization change occurs due to an external magnetic field, it is convenient to detect the direction of a small magnetic field using this magnetization change point. Furthermore, it has good frequency characteristics and can be processed by vapor deposition, making it easy to process, miniaturized, and inexpensive, making it suitable for magnetic recording/reproducing heads.

Next, a magnetic signal detection circuit using such an MR element will be explained with reference to FIG.

Now, in FIG. 9, when DC 12V is applied between E and F, a stable voltage of IOV is generated at point D by transistor TRI and Zener diode Z. If a resistor R1 of 9Ω is connected between the current point and the point A, and an MR element 27 having an internal resistance of IKΩ is connected between the point A and E', D-A-
The direct current resistance between E' is 9Ω+IKΩ, which is IOKΩ, and the current flowing during this period is IOV/IOKΩ=1 mA. That is, a current of 1 mA is constantly flowing through the MR element 27.

In this state, when the magnetic field of the recording medium 4 in front of the MR element 27 changes, the internal resistance of the MR element 27 is approximately 2% of the internal resistance IKΩ.
Suppose that 0Ω changes. At this time, the voltage at point A is 0.001
AX20Ω = 20m V change. Therefore, only the exchange portion of this 20 mV signal is taken out by the capacitor C, inputted to the base of the transistor TR2, and outputted from the transistors TR2 to TR5.

By the way, since the signal extracted from the MR element in this way is weak, if the input wire from the MR element to the base of the transistor TR2 is made long, external noise will be mixed in, resulting in malfunction. Therefore, in the past, noise countermeasures were taken using a shielded wire 12 as shown in FIG. 2, but in the present invention, more complete noise countermeasures are taken as shown in FIG.

That is, as shown in FIG. 5, an integrated circuit chip 28 weighing several grams is attached to the side surface of the substrate 26 on which the MR element 27 is formed, and a terminal pattern input terminal 30 continuous to the MR element 27 is attached.
, and the output terminal 31 are connected with a short metal wire. As a result, there is no need to run a shielded wire as long as 100 to 200 am as in the conventional case, and noise countermeasures are almost perfect.

In the example shown in FIG. 5, capacitors 32 and the like that cannot be accommodated in the integrated circuit chip 28 are connected with metal wires between vapor deposition patterns on the substrate and between the chips. The circuit configuration shown in FIG. 5 is a mounting method for a so-called mixed product circuit, but of course the board 26 may also be highly integrated using 8102 or the like, and from a magnetic point of view it is similar to the 5i02 board. There is no problem even if the main magnetic pole 1 and the MR element 27 are deposited by vapor deposition.

Furthermore, in order to completely prevent magnetic noise and electrical noise from entering from the outside, it is sufficient to adopt a structure in which the auxiliary magnetic pole and the main magnetic pole are housed in a case as shown in FIG.

In FIG. 10, the same parts as in FIGS. 1 and 2 are given the same reference numerals.

In FIG. 10, the substrate 26 provided with the main magnetic pole and the MR element 27 is housed in a case 33 made of a high magnetic permeability magnetic material fixed to the free end side of the head arm 6, and fixed with resin 34, and as a whole the main It constitutes a magnetic pole unit 35.

Further, the auxiliary magnetic pole 2 is housed in a case 36 made of a high permeability magnetic material and fixed to the carriage 5 side, and is fixed with resin 34 together with the coil and coil, and constitutes an auxiliary magnetic pole unit 37 as a whole. If such a structure is adopted, the protection structure against external noise is complete.

The main magnetic pole unit 35 and the auxiliary magnetic pole unit 37 are respectively provided with terminals 35a and 37a for connection to the outside.

On the other hand, FIG. 11 shows the structure of a magnetic head configured so that magnetic recording and reproduction can be performed on both sides of a magnetic recording medium.

That is, those indicated by reference numeral 38 are recording/reproducing units, one of which is fixed to the carriage 5 and the other to the head arm 6 side. In each recording/reproducing head unit 38, a main magnetic pole unit 35 and an auxiliary magnetic pole unit 37 are housed inside a shield case 39, and the gap between the two is magnetically shielded by a resist plate 40.

Further, the auxiliary magnetic pole unit and the main magnetic pole unit in the upper unit 38 are configured to face each other.

If such a structure is adopted, recording and reproduction can be performed on both sides of the magnetic recording medium exemplified as the magnetic disk 19.

As is clear from the above description, according to the present invention, the level of conversion of magnetic recording on a magnetic recording medium into an electrical signal on the main pole side of a perpendicular magnetic recording type magnetic head is high, and noise signals may be mixed in. It is possible to obtain a stable magnetic head without any problems.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the basic structure of a conventional perpendicular magnetic recording magnetic head, FIG. 2 is an exploded perspective view illustrating a conventional drive mechanism, and FIGS. 3 is an explanatory diagram showing the basic structure of the present invention, FIG. 4 is a partially enlarged perspective view showing the MR element formation state, and FIG. 5 is a perspective view illustrating the mounting state of the MR element. , Figure 6 is MR
Diagrams showing the relationship between the internal resistance value of the element and magnetic field strength, Figures 7 (A) and (B>) are explanatory diagrams showing the relationship between the MR element and the direction of magnetization, and Figure 8 shows the relationship between the main magnetic pole and the MR element. A side view showing the dimensional relationship, FIG. 9 is an amplifier circuit diagram, and FIG.
FIG. 11 is a longitudinal sectional side view illustrating another embodiment of the present invention. 1... Main magnetic pole 2... Auxiliary magnetic pole 4... Magnetic recording medium 5... Carriage 6... Head arm 18... Magnetic disk 26... Substrate
27...MR element 28...Integrated circuit chip 3
5...Main magnetic pole unit 37...Auxiliary magnetic pole unit 38...Recording/reproducing head unit 39...Shield case 40...Shield plate Patent applicant Canon Electronics Co., Ltd. Agent Patent attorney Taku Kato No. 9 Figure 10 Figure 11 35 40 '37 Ω A

Claims (1)

[Claims] A perpendicular magnetic recording/reproducing magnetic head using a main magnetic pole and an auxiliary magnetic pole, characterized in that a magnetoresistive element for converting magnetic recording on a magnetic recording medium into an electric signal is provided on the main magnetic pole side. magnetic head.