JPH04134678A - Structure preventing dislocation for magnetic head - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary] This invention relates to a structure for preventing misalignment of a magnetic head in a complete carriage for positioning the magnetic head, and a single professional unit by integrating a plurality of head arms.

In the integrated carriage complete body consisting of
With the aim of preventing off-track caused by variations in the amount of thermal deformation between each head arm, we have developed an integrated carriage assembly consisting of multiple head arms integrated into a single block. The amount of thermal deformation of each head arm is measured, and a correction plate having a coefficient of thermal expansion different from that of the head arm is attached to the side surface of the head arm, so that the amount of thermal deformation of each head arm is made to be the same.

[Industrial application field]

A magnetic disk device used as a file device in an information processing system usually has a plurality of magnetic disks, and a magnetic head arranged corresponding to each magnetic disk surface is used to seek a predetermined track using a carriage. Then, data is recorded/reproduced. The present invention relates to a structure for preventing the positional displacement of the magnetic head in a completed carriage for positioning the magnetic head in this manner.

[Prior Art] FIG. 6 is a perspective view of a completed carriage nozzle of a magnetic disk device. The completed carriage refers to a carriage in a state in which a magnetic hend can be mounted. D... is a magnetic disk, which has a magnetic recording film on the surface of a non-magnetic substrate. Magnetic heads hi and ho record/reproduce data on the magnetic recording film by moving in the radial direction of the magnetic disk D and seeking.

It is a single carriage and is rotated back and forth in the direction of arrow a1 by an actuator M such as a voice coil motor. The motor drive circuit 17 receives instructions from the MPU 15 and drives the actuator M. The carriage 1 integrally has a main block 3 on which the head arms 2 are mounted, and a sub-block 4 is fixed to the main block 3 with bolts 14.

The main block 3 and the sub-block 4 each have a protruding collar portion on which each head arm 2 is mounted, and each head arm 2 is placed on the upper surface of each tail portion. Then, a draw bolt 5... is inserted into the main block 3 corresponding to each head arm 2..., and the hook portion 6 at the tip is inserted into an inclined hole 7 formed in each head arm 2... It's hooked. When the nuts 8 of each draw bolt 5 are tightened, each head arm 2
It is pressed against the reference surface 9.10 and the horizontal surface of the tail portion by the hook portion 6, and is fixed.

An inner magnetic head hi and an outer magnetic head ho are attached to the tip of each head arm 2, corresponding to each magnetic disk surface.

In this device, data is recorded/reproduced by driving a carriage l with a drive motor and seeking magnetic heads hi and ho to a predetermined track.

At the rear end of the carriage 1, there is a movable stopper 11 for regulating the movement range of the magnetic heads hi, ho in case the carriage l goes out of control, and on the device side there are two fixed stoppers 12 and 13. have.

That is, when the carriage 1 runs out of control toward the inner side, the movable stopper 11 collides with the rubber portion g of the inner side stopper 12 and stops, and when the carriage 1 runs out of control toward the outer side, it collides with the rubber portion g of the outer side stopper 13. and stop.

The completed carriage has a structure in which, as described above, a large number of head arms 2 are pressed and fixed to the upper surface of the collar and the reference surface 9.10 by each draw bolt 5. In this way, a typical completed carriage is constructed by assembling a large number of parts. Therefore, as mentioned above, the impact when the carriage l runs out of control causes each head arm 2 to shift in the in-plane direction of the magnetic disk D, and as a result, each magnetic head h1% ho
The position of the track is shifted and you are unable to seek to the desired track.
There is a risk that off-tracking will occur, resulting in system failure and causing great damage to users.

Particularly, in the case of a completed stacked carriage as shown in FIG. 7, off-trunk is likely to occur due to impact. FIG. 7(a) is a plan view, and FIG. 7(b) is a partially sectional front view. The completed stacked carriage has a structure in which, for example, 7 to 11 head arms 2 are directly stacked, and bolts 18 are inserted into each and tightened and fixed. Also,
The movable stopper also has a structure in which parts of the stoppers extending from each head arm 2 are stacked, so that some parts of each stopper come into contact with the fixed stopper and others do not come into contact with the fixed stopper. As a result, a shift occurs between the head arm in which a portion of this stopper abuts the fixed stopper and the head arm in which it does not abut, causing the magnetic heads hi, ho at the tips of the head arms to go off-track.

Another attempt has been made to integrate the head arms 2 into a single block as shown in FIG. 8, thereby making it impossible for them to move relative to each other due to impact. Note that 19 is a support shaft of the completed carriage. This integrated carriage complete body has a small number of parts and is easy to manufacture and assemble.

However, as a new problem, each head arm 2...
It was found that off-track was caused by variations in the amount of thermal deformation. FIG. 9 shows off-track measurement results due to temperature changes, and is an example in which test data was written at 25°C, read at 0°C, and then read after the temperature was raised to 45°C. Therefore, the off-track amount is a value when the temperature is increased by 45°C compared to the case of 0°C.

[Problem to be solved by the invention]

Therefore, since each head arm 2... is stacked,
■ Column (1) of Table 91 is the value of this off-track amount,
When the off-track amount of the servo head SR is set to 0, the head arm below the servo head SR is off-track to the inner side, and the servo head SR
The amount of off-track increases as the distance from the road increases.

Further, the head arm above the servo head SR is off-track toward the outer side, and the amount of off-track increases as the distance from the servo head SR increases.

In recent years, as the density and capacity of magnetic disk devices have increased, it has become necessary to improve the positioning accuracy of the magnetic head. must be resolved.

The technical problem of the present invention is to address such problems and to solve the problem of reducing the amount of thermal deformation between each head arm in an integrated carriage complete body formed by integrating a plurality of head arms into a single block. The objective is to prevent off-tracking caused by variations.

[Means for Solving the Problems] (1) FIG. 1 is a perspective view illustrating the basic principle of the magnetic head misalignment prevention structure according to the present invention.

Reference numeral 20 denotes an integrated carriage complete body, which is constructed by integrating a plurality of head arms 2 into a single block.

Since the amount of thermal deformation of each head arm 2 is different, the amount of thermal deformation of each head arm 2 is measured, and a correction plate 21 having a different coefficient of thermal expansion from that of the head arm 2 is pasted on the side of the head arm 2. By this, each head arm 2
... so that the amount of thermal deformation is the same.

(2) The amount of thermal deformation of each head arm 2 is measured, and a correction plate 21a made of a material having a smaller coefficient of thermal expansion than the head arm 2 is pasted at a position where the amount of thermal deformation is large.

(3) Conversely, place the head arm 2 in a position where the amount of thermal deformation is small.
A configuration in which a correction plate 21b made of a material with a larger coefficient of thermal expansion is attached may also be used.

[Effect]

By measuring the amount of thermal deformation of each head arm 2..., the thermal deformation characteristics of each head arm 2... can be determined. The present invention has a structure in which a correction plate 21 having a different coefficient of thermal expansion from the head arm 2 is attached to the side surface of the head arm 2 according to the thermal deformation characteristics of each head arm 2.

For example, a correction plate made of a material having a smaller coefficient of thermal expansion than the head arm 2 is attached to a position where the amount of thermal deformation is large. In the figure, assuming that the amount of thermal deformation of the inner side portion 21 of the head arm of HAI and HA8 to 1O is large, a correction plate 21a made of a material with a smaller coefficient of thermal expansion than the head arm 2 is pasted at that position. Since the correction plate 21a is attached, the IAI and HA
Thermal deformation of the inner side portions 21 of head arms 8 to 10 is suppressed, and the amount of thermal deformation is the same as that of other head arms 2 to which no correction plate is attached, so that each head arm 2...・It is possible to prevent off-trunk caused by variations in the amount of thermal deformation between the parts.

On the other hand, if the amount of thermal deformation of the inner side portion 21 of the head arms HA4 and HA5 is small, for example, by pasting the correction plate 21b made of a material with a larger coefficient of thermal expansion than the head arm 2 at that position, This correction plate 21b
As a result, the thermal deformation of the inner side portion 21 of the head arm of HA4, )HA5 is promoted, and the amount of thermal deformation is the same as that of other head arms to which the correction plate 21b is not attached, and each head arm 2. ... Off-track due to variations in the amount of thermal deformation between the two can be prevented.

The correction plates 21a and 21b have dimensions (lengths) corresponding to the amount of thermal deformation.

Note that the correction plate 21 has a larger coefficient of thermal expansion than the head arm.
By using both a and the small correction plate 21b,
The amount of thermal deformation of all the head arms may be the same, or only one may be used. Also, in the figure, the correction plate is pasted on the inner side 21, but it may be pasted on the outer side 2o, or both sides (2i
, 2o).

〔Example〕

Next, how the magnetic head misalignment prevention structure according to the present invention is actually implemented will be explained using examples. Second
The figure shows the complete integrated carriage shown in Figure 8.
This is a state in which a correction plate is attached according to the present invention, and (a) is a plan view and (b) is a rear view.

In the conventional completed carriage shown in FIG.
As is clear from the thermal deformation characteristics in Figure and Table 1, when viewed from the lowest head arm HAO, the upper head arm has a thicker off-track amount (and all of the off-tracks are on the outer side). track.Therefore, the second
As shown in Figure (b), a complete integrated carriage was fabricated by attaching a long correction plate 21a to the upper head arm, which has a large amount of thermal deformation.

The dimensions of the correction plate 21a were determined according to the flowchart shown in FIG. In other words, each head arm 2...
The off-track amount was measured for each magnetic head HD attached to the magnetic head HD, and the off-trunk value in column (1) of Table 1 was obtained. Next, from this value, an off-track mode (curve) as shown in FIG. 9 is created, and a correction target value is determined. In the illustrated example, the magnetic heads of the head arms of HAO and IAI are set as correction target values, and the magnetic heads of the head arms of HAO and IAI are set as correction target values.
The amount of thermal deformation of the other Radarms was made to be the same for AO and HAI.

The illustrated completed carriage has two magnetic heads, upper and lower, mounted on one head arm.
As shown in the figure, the off-track amount for each head arm (IA) is obtained by measuring the off-track amount of each magnetic head HD and then obtaining an average value. Then, from this average value, the correction amount for each head arm 2... was calculated, and the value of (3) 11111 in Table 2 was obtained.

Next, the length of the correction plate 21a is calculated based on this correction amount. The correction plate 21a has a thermal expansion coefficient of 17X1.
0-'/''C JIS standard SUS 304 C5P was used, and the dimensions were 3w+m in width and 0.1mm in thickness.In this case, the length of the correction plate 21a is L = -A-g-+
4 (mm). The integrated carrier and jig were made of a magnesium alloy with a thermal expansion coefficient of 26X10-''/''C.

In this way, the length of each head arm is determined as shown in column (4) of Table 1, and a correction plate is made and attached to the side of the corresponding head arm, as shown in Figure 2. A complete integrated carriage as shown in the figure is obtained. Note that the correction plate 21a is attached from the base of each head arm. Araldite AV 138 was used as the adhesive.

FIG. 4 shows the results of measuring the amount of off-track under the same conditions as in FIG. 9 for the completed carriage after pasting the correction plate as shown in FIG. As is clear from this figure, even after the temperature increased by 45° C., off-track was significantly suppressed, and variations in the amount of off-track were also reduced. After all, according to the present invention, it can be seen that the difference in thermal expansion of different metals appears linearly as a correction amount due to the bimetallic effect caused by bonding different metals together.

However, since off-track is not completely eliminated, off-track can be eliminated by making and attaching a correction plate again to the head arm of the head that is off-track.

By the way, as shown in the characteristic curve of FIG. 9, although there is some regularity in the off-track tendency, there are also random parts. This regular portion is thought to be due to the asymmetrical shape of the heel/rad arm shown in FIG. 8.

Therefore, as shown in Figure 5, the shape of the head arm is
When the shape was made bilaterally symmetrical with respect to the center line C, regular off-trunks were significantly reduced, but irregular off-tracks still remained. This is due to the fact that when molding the complete integrated carriage by die-casting, the way the hot water flows to each door arm is different due to the difference in distance from the sprue, and the presence or absence of cavities. It is thought that the amount of thermal deformation varies randomly depending on each head arm.

In this way, even if off-track occurs irregularly in each head arm 2..., for the head arm with a large amount of thermal deformation, either attach a correction plate with a coefficient of thermal expansion smaller than that of the head arm, or By attaching a correction plate having a larger coefficient of thermal expansion than the head arm to the head arm, which has a small amount, it is possible to suppress off-tracks that occur randomly. Titanium (Ti) is suitable as a material having a larger coefficient of thermal expansion than the head arm made of Mg'PAl or the like.

In the case of FIG. 5, since the flexible printed cable 22 is attached to the outer side surface of each head arm 2, the correction plate is attached to the inner side surface 21 of the head arm 2.

[Effects of the Invention] As described above, according to the present invention, each head arm 2...
By measuring the amount of thermal deformation of each head arm, and attaching a correction plate with a coefficient of thermal expansion different from that of the head arm to the side surface of each head arm, each head arm 2...
The structure is such that the amount of thermal deformation is the same. Therefore, regardless of the shape of the head arm, off-trunk caused by variations in the amount of thermal deformation of each head arm due to temperature changes can be prevented, and it can easily support higher density and larger capacity magnetic disk drives. can.

[Brief explanation of the drawing]

Fig. 1 is a perspective view illustrating the basic principle of the magnetic head misalignment prevention structure according to the present invention, Fig. 2 is a plan view and rear view showing a first embodiment of the present invention, and Fig. 3 is a first embodiment. FIG. 4 is a diagram showing off-track measurement results for the completed carriage of the first embodiment, FIG. 5 is a plan view and a front view showing the second embodiment of the present invention. , Fig. 6 is a perspective view of a completed carriage of a magnetic disk drive, Fig. 7 is a plan view and a partially sectional front view of a completed stacked carriage, and Fig. 8 is a plan view of a completed conventional integrated carriage. FIG. 9 is a diagram showing the results of off-trunk measurements of a conventional integrated type carriage complete body. In the figure, D... is a magnetic disk, 2..., HA
O~HAIO is the navel arm, 21 is the inner side, 20
is outer side, hi, ho, HD, HDOO~HD
20 is a magnetic head, 19 is a support shaft, 20 is an integrated carriage complete body, 21 is a correction plate, 21a is a correction plate made of a material whose thermal expansion coefficient is smaller than that of the head arm, and 21b is a correction plate whose thermal expansion coefficient is larger than that of the navel arm. Each corrector plate made of material is shown. Patent applicant Fujitsu Co., Ltd. sub-agent Patent attorney Yasushi Fukushima Text name 1 Senma 6-Itari Tora Kata ■ Peyari, 7″;

Claims (1)

[Claims] 1. In an integrated carriage complete body made up of a single block by integrating a plurality of head arms, the amount of thermal deformation of each head arm (2...) is measured, A magnetic head misalignment method characterized by aligning the amount of thermal deformation of each head arm (2...) by pasting a correction plate (21) having a different thermal expansion coefficient from that of the head arm on the side surface of the head arm. Prevention structure. 2. Integrate multiple head arms to form a complete integrated carriage consisting of a single block, measure the amount of thermal deformation of each head arm (2...), and measure the thermal deformation of each head arm (2...). In a structure in which a correction plate with a different coefficient of thermal expansion is attached to the head arm, a correction plate (21a) made of a material with a smaller coefficient of thermal expansion than the head arm (2) is attached at a position where the amount of thermal deformation is large. Features a magnetic head misalignment prevention structure. 3. Integrate multiple head arms to form an integrated carriage complete body consisting of a single block, measure the amount of thermal deformation of each head arm (2...), and measure the amount of thermal deformation of each head arm (2...). In a structure in which a correction plate with a different coefficient of thermal expansion is attached to the head arm, a correction plate (21b) made of a material with a larger coefficient of thermal expansion than the head arm (2) is attached at a position where the amount of thermal deformation is small. Features a magnetic head misalignment prevention structure.