JPS647503Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic disk device that can prevent off-track caused by misalignment of a magnetic head due to a temperature difference between recording and reproducing.

The magnetic disk device is generally composed of a magnetic disk rotatably mounted within a housing, a magnetic head that faces the magnetic disk in a floating state and reads information stored on the magnetic disk, and an actuator that supports the magnetic head so that it can move forward and backward in the radial direction of the magnetic disk.
The actuator unit includes a rotation source, a first arm with one end attached to the magnetic head, a second arm with one end engaged with the rotation source, a shaft fixed to the other end of the first and second arms, and a pair of bearings provided between the shaft and the housing to rotatably support the shaft. In this case, the housing is usually made of aluminum from the viewpoint of workability and weight reduction, and there is a significant difference in linear expansion coefficient between the housing and the bearing made of stainless steel (SUS). Therefore, when the ambient temperature rises, the gap between the bearing and the housing expands due to the difference in linear expansion coefficient between the members, causing the shaft supporting the arm to tilt or swing.

From the above, if there is a temperature difference between the time of recording on a magnetic disk and the time of playback, the tilt of the shaft will cause misalignment of the positioning of the magnetic head or vibration. Become. If the positioning of the magnetic head is misaligned or shakes in this way, the magnetic head will move on a different trajectory from the trajectory it took when recording on the magnetic disk, resulting in so-called off-track, which can cause playback errors. It turns out.

Therefore, various measures have been taken to prevent play between the bearing and the housing even when the ambient temperature changes. For example, a structure is known in which the outer race of the bearing is always pressed in one direction by a spring so that no looseness occurs between the bearing and the housing even when the temperature changes. However, in a small magnetic disk device, the bearing itself is small, and therefore the bearing pressing member made of a spring or the like must be extremely small, which has the disadvantage that manufacturing and assembly thereof is troublesome.

The present invention was devised in view of the drawbacks of the prior art described above, and is a magnetic disk device that prevents playback errors due to off-track even if there is a temperature change between recording and reproducing information on the magnetic disk. The purpose is to provide

In order to achieve this object, the present invention includes a housing made of a metal material and having cylindrical portions on both sides in the thickness direction, a shaft provided through the housing in the thickness direction, and a shaft. A pair of bearings are provided in each of the cylindrical parts for rotatable support and are made of a metal material having a coefficient of linear expansion smaller than that of the housing, and a magnetic head is attached to one end. , a first arm having the other end fixed to the protruding end of the shaft, and a second arm having one end engaged with a rotation source and the other end fixed to the protruding end of the shaft, the rotation In a magnetic disk device, the magnetic head is moved forward and backward in the radial direction of the magnetic disk through first and second arms by rotating a source, and information is recorded and reproduced. Among them, in order to regulate the amount of clearance between one bearing located on the opposite side of the first arm and one cylindrical part in which the one bearing is accommodated, the coefficient of linear expansion of the housing is adjusted. The present invention is characterized in that a restraining member having a smaller coefficient of linear expansion is fixedly provided on the opening side of the first cylindrical portion.

With this configuration, due to temperature changes between recording and reproducing information, one bearing located on the opposite side of the first arm and one cylindrical portion in which the bearing at that position is accommodated. Even if the amount of clearance between the housing changes and the first arm to which the magnetic head is attached is shaken due to tilting of the shaft, the opening side of the first cylindrical part will have a linear expansion coefficient smaller than that of the housing. Since the shaft is restrained by a restraining member having a coefficient, tilting of the shaft is reliably prevented, and the positioning of the magnetic head is reliably performed.

Embodiments of the present invention will be described below based on the drawings.

First, FIGS. 1 and 2 show a first embodiment of the present invention. In the figures, 1 indicates a magnetic head, and the magnetic head 1 is a magnetic disk ( (not shown) for writing and reading data. Reference numeral 3 designates an actuator portion that supports the magnetic head 1 so that it can move forward and backward in the radial direction of the magnetic disk. The actuator section 3 is generally composed of a step motor 4 as a rotation source, an arm 5, and a shaft 6 that rotatably supports the arm 5 and serves as a pivot point for the arm 5. Arm 5 is the first arm on the head side.
The first arm 5A has one end attached to the magnetic head 1, and the other end fixed to the shaft 6. On the other hand, the second arm 5B has both ends of a steel belt 7 fixedly attached to one end thereof, the middle part of the steel belt 7 is fixed to the output shaft of the step motor 4, and the other end is attached to the first end. Like the arm 5A, it is fixed to the shaft 6.

As shown in FIG. 2, the shaft 6 is rotatably supported by a pair of bearings 8 and 9 of the housing 2. That is, the housing 2 is formed with a cylindrical portion 2A that protrudes inwardly of the housing 2 and a cylindrical portion 2B that protrudes outwardly, facing each other on both sides in the thickness direction, and each of the cylindrical portions 2A, 2B. A through hole 10 is bored in the center of the hole. The shaft 6 is inserted into the through hole 10, and the bearings 8 and 9 are inserted into the shaft 6 and the cylindrical parts 2A and 2B, respectively.
It is interposed between. The bearing 8 has an outer race formed at the upper part of the cylindrical part 2 and a step part formed at the top of the cylindrical part 2.
The inner lace is sandwiched between the inner lace and a pressing plate 11 provided on the upper edge of the inner lace, and is fixedly provided by being pressed against the pressing plate 11 by a spring 12. On the other hand, the inner race of the bearing 9 is held between the stopper member 6A provided at the lower end of the shaft 6 and the inner wall of the housing 2.
The outer race is free and serves as an idle bearing. Then, a set screw 1 provided on the cylindrical portion 2B
3 to prevent play from occurring between the bearing 9 and the inner wall of the cylindrical portion 2B under normal conditions.

Next, 14 is a bolt 1 attached to the lower end of the cylindrical portion 2B.
The restraint member 14 is formed of a member having a linear expansion coefficient smaller than that of the housing 2, preferably the same member as the bearing 9. The restraining member 14 also functions as a lid that prevents communication between the inside and outside of the housing 2 through the through hole 10 formed in the housing 2.

The magnetic disk device according to the present invention has the above-described configuration, and in order to read information recorded on the magnetic disk, the magnetic disk is rotated with the magnetic head 1 facing the magnetic disk.
At the same time, by driving the step motor 4, the arm 5 is rotated about the shaft 6, and the magnetic head 1 is advanced inward in the radial direction of the magnetic disk. At this time, since the magnetic head 1 is in a floating state with respect to the magnetic disk, the magnetic head 1 faces a position that is accurately positioned with respect to the magnetic disk, and is prevented from wobbling during operation. Otherwise, off-track will occur.

By the way, since the coefficient of linear expansion of the housing 2 made of aluminum material is larger than that of stainless steel, which is the material of the bearing 9, when the ambient temperature rises, the amount of increase in the outer diameter of the bearing 9 due to thermal expansion is greater than that of the stainless steel that is the material of the bearing 9. The amount of diameter expansion of the cylindrical portion 2B is greater. However, the lower end edge of the cylindrical portion 2B has a linear expansion coefficient smaller than that of the housing 2, preferably the bearing 9.
Since the restraining member 14 formed of a member having the same linear expansion coefficient as the cylindrical portion 2 is fixedly provided, the cylindrical portion 2
It is possible to restrain the thermal expansion of B, and to restrict the gap between the bearing 9 and the cylindrical portion 2B from expanding, thereby preventing the occurrence of play therebetween. Therefore, the shaft 6 is stably supported vertically by the bearings 8 and 9, the movement of the magnetic head 1 is stabilized, and the occurrence of off-track is prevented.

Furthermore, the inside of the housing 1 that houses the magnetic disk needs to have a structure that does not allow foreign matter such as dust to enter.
Since the housing 2 functions as a lid, it is possible to prevent dust and the like from entering the housing 2 through the through hole 10.

Next, FIG. 3 shows a second embodiment of the present invention. In this embodiment, the second arm 5B on the step motor side is not provided inside the housing 2. It is located outside. Further, the restraining member 21 attached to the lower end edge of the cylindrical portion 2B is formed in a stepped shape projecting downward, and has an insertion hole 21A formed in the center thereof. The shaft 22 has a first arm 5A attached to a portion that projects inside the housing 2, and its lower end extends from the cylindrical portion 2B to the outside of the housing 2 through the insertion hole 21A of the restraining member 21. A second arm 5B is attached to this portion. Furthermore, the restraining member 2
1, around the insertion hole 21A there is a magnetic seal 2 made of a magnet etc. that attracts dust etc.
Components other than those to which 3 is attached are the same as those in the first embodiment, so they will be given the same reference numerals as in FIG. 2 and their explanation will be omitted.

Even with the above-mentioned configuration, the restricting member 21 restricts the diameter expansion of the cylindrical portion 2B due to thermal expansion, and the shaft 22 is stably supported in a vertical state and can be prevented from tilting. This is similar to the embodiment.

On the other hand, since it is necessary to attach the shaft 22 to the second arm, it is necessary to form an insertion hole 21A in the restraint member 21, so that the inside and outside of the housing 2 are in communication with each other. However, since the magnetic seal 23 is attached to the restraining member 21, foreign matter such as external dust is attracted and collected by the magnetic seal 23 and does not enter the inside of the housing 2.

As described in detail above, according to the magnetic disk device according to the present invention, of the pair of bearings provided in each cylindrical portion of the housing to support the shaft,
In order to restrict the amount of clearance between one bearing located on the opposite side of the first arm and one cylindrical part in which the one bearing is accommodated from changing, a line smaller than the coefficient of linear expansion of the housing is provided. Since the restraint member having an expansion coefficient is fixedly provided on the opening side of the first cylindrical part, the space between the first cylindrical part and the first bearing is always restrained by the restraint member. Occurrence of backlash etc. in between is prevented. As a result, the shaft that supports the first arm to which the magnetic head is attached can be supported extremely stably relative to the housing, and even when the ambient temperature changes, the shaft is prevented from tilting, and the shaft is not tilted during recording and playback. This eliminates the occurrence of off-track and ensures reliable recording and playback.

[Brief explanation of drawings]

1 and 2 show a first embodiment of the present invention, in which FIG. 1 is an external view of a magnetic disk device, FIG. 2 is a cross-sectional view in the direction of the − arrow in FIG. 1, and FIG. 2 is a sectional view similar to FIG. 2 showing a second embodiment of the present invention. 1...Magnetic head, 2...Housing, 3...
Actuator section, 4... Step motor, 5...
...Arm, 5A...First arm, 5B...Second
arm, 6, 22... shaft, 8, 9... bearing, 10... through hole, 14, 21... restraint member,
21A...Insertion hole, 23...Magnetic seal.

Claims (1)

[Scope of utility model registration request] A housing made of a metal material and having cylindrical parts on both sides in the thickness direction, a shaft provided through the housing in the thickness direction, and a shaft inside each of the cylindrical parts to rotatably support the shaft. a pair of bearings formed of a metal material having a coefficient of linear expansion smaller than that of the housing, a magnetic head attached to one end, and the other end fixed to the protruding end of the shaft. a first arm having one end engaged with the rotation source;
and a second arm whose other end is fixed to the protruding end of the shaft, and by rotating the rotation source, the magnetic head is moved forward and backward in the radial direction of the magnetic disk via the first and second arms. In the magnetic disk device for recording and reproducing information, one of the pair of bearings is located on the opposite side of the first arm, and the other is a cylinder in which the one bearing is housed. A restraining member having a coefficient of linear expansion smaller than the coefficient of linear expansion of the housing is fixedly provided on the opening side of the first cylindrical part in order to restrict the amount of clearance between the first and second cylindrical parts from changing. magnetic disk device.