JPH04349284A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To obtain a magnetic disk device to uniformize the temperature of a base and a cover by changing the shape of the shaft diameter of a side mounting a heating element with the shape of the side no mounting heating element. CONSTITUTION:The magnetic disk device is provided with a spindle shaft 17 and a actuator shaft 19 having a shaft end whose diameter is enlarged step- likely at the side of the cover. Then, although heat generated from an electric circuit board 15 and heat conducted through an actuater motor magnet 12b flow into the base 13, since the outside diameter of the shaft end part of the opposite side is larger than the outside diameter of the shaft end part fixed to the base 13 side loading the electric circuit board 15, etc., and thermal resistance is small and the heat inflow to the cover side is large, temperature difference between the base 13 and the cover 14 is reduced and uniformized.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk drive in which thermal distortion is reduced, that is, off-track due to heat is corrected.

0002

2. Description of the Related Art FIG. 8 is a sectional view showing an example of a conventional magnetic disk device disclosed in Japanese Unexamined Patent Publication No. 1-248356, Utility Model Application Publication No. 2-101365, etc. In the figure, 1 is a magnetic disk; 2 is a magnetic disk drive; a magnetic head; 3 a spindle hub for holding the magnetic disk; 4 a spindle motor magnet;
5 is a spindle motor coil, 6 is a spindle bearing for rotationally supporting the spindle hub, 7 is a spindle shaft serving as a central axis of rotation, 8 is an arm block of an actuator that supports the magnetic head 2, and 9 is an arm block for swinging the magnetic head. 10 is an actuator bearing that supports the arm block 8, and 11 is an actuator that is an element of an actuator motor for swinging the magnetic head. a coil; 12 is an actuator motor magnet that constitutes the coil and motor; 13 is a base for supporting the above-mentioned parts and other auxiliary parts such as a filter and a clamp mechanism (not shown); 14 is a block for blocking dust from the outside world; 15 is an electric circuit board on which a control circuit is mounted, and 16 is a screw for holding the electric circuit board 15 on the base.

Next, the operation of the conventional example will be explained. In FIG. 8, when the magnetic disk is in a normal operating state, it has various heat sources. Heat generation sources include heat due to shaft loss from the spindle motor coil 4 and spindle bearing 6 due to rotation of the spindle motor, heat generated due to wind loss caused by the rotating magnetic disk 1 and hub 3, heat generated from the actuator motor coil 11, and heat generated from the actuator motor coil 11. These include heat from the bearing 10, heat generated by wind damage due to swinging of the arm block 8, and the like. If such a heat source is present, heat will be distributed within the magnetic disk device, particularly within the assembly housed in the base 13 and cover 14.

On the other hand, in the conventional device as shown in FIG. 8, the lower end of the spindle shaft 7 and the actuator shaft 9 are held by the base 13 and the upper end by the cover 14 to increase rigidity and minimize mechanical distortion. Data recording density is increased. Further, these shafts have a symmetrical structure in which the diameters on both sides, including the portions usually connected to the cover side and the base side, are uniform. Therefore, if the arrangement of the heat source is asymmetrical with respect to the structure, the distribution of heat generated during operation will be uneven, resulting in thermal distortion. In the conventional device, as shown in FIG. 8, the electric circuit board 15 is held on one side of the base 13 or the cover 14 for structural reasons. Further, the actuator motor is also fixed to either the base or the cover like the magnet 12.

FIG. 9 is a diagram illustrating the movement of heat by conduction, that is, heat transfer. The heat generated by the spindle motor coil 5 and actuator motor coil 11 is evenly spread to the base and cover because the spindle shaft 7 and actuator shaft 9 are formed uniformly, but the heat generated from the electric circuit board 15 is In the example No. 9, the water mainly flows from the base 13 side. Furthermore, the heat generated by the coil 11 is also easily transmitted to the base side through the actuator motor magnet 12. With this configuration, a temperature difference occurs between the base 13 and the cover 14.

FIG. 10 is a diagram illustrating the resulting temperature distortion. As mentioned above, if a temperature difference occurs between the base and the cover, the center distance between the spindle shaft 7 and actuator shaft 9 on the base side and the cover side will be different because the base and cover are usually made of the same material. come. In the figure, when a temperature of ΔT is generated between the base and the cover, the difference ΔA between the shafts in the upper and lower directions is ΔA=AαΔT, assuming that the coefficient of thermal expansion of the material is α (1/° C.). If there is a difference in ΔA between the top and bottom, the magnetic disk and magnetic head are held indirectly by the spindle shaft and actuator shaft, respectively, so it is inevitable that
This causes a relative positional shift between the magnetic head and the magnetic disk. In FIG. 10, the relative movement between the shafts is shown by broken lines, and the amount of positional deviation between the head and the disc is shown as Δx. Such positional deviation is called off-track, and if it occurs during data recording and reproduction, it will lead to errors.

[0007]

[Problem to be Solved by the Invention] Since the conventional magnetic disk drive is configured as described above, a temperature difference occurs between the base and the cover, which causes off-track in the head and disk, resulting in data reading errors. There were problems such as.

The present invention was made to solve the above-mentioned problems, and aims to provide a magnetic disk device in which the temperature of the base and cover are made uniform in order to suppress off-track of the head disk. purpose.

[0009]

[Means for Solving the Problems] In the magnetic disk device according to the present invention, first, in the first invention, the shapes of both ends of either or both of the spindle shaft and the actuator shaft are changed. In the second invention, the shapes of the cover and base that are in contact with the spindle shaft and the actuator shaft are changed. In the third invention, the thermal conductivity of the material of the connecting parts at both ends of either or both of the spindle shaft and the actuator shaft is changed.

0010

[Operation] In the magnetic disk drive of the present invention, first, in the first invention, the shape of the shaft diameter on the side where the heating element is mounted is different from the shape on the side where the heating element is not mounted, so the cover The temperature between the base and the base is equalized. In the second invention, since the shapes of the cover and base that support the shaft are changed, heat transfer is made uniform and the temperature difference between the cover and the base is reduced. In the third invention, since the thermal conductivity of the connecting parts at both ends of the shaft is changed, the temperature between the cover and the base is equalized.

[0011]

【Example】

Example 1. Embodiments of the invention will be described with reference to the drawings. FIG. 1 is a structural diagram of the first embodiment, and in the figure, 17, 1
Reference numeral 9 denotes a spindle shaft and an actuator shaft, each having a shaft end whose diameter increases stepwise on the cover side. Since the other components are the same as those of the conventional example, explanations of the symbols will be omitted.

An embodiment of the first invention will be described below with reference to FIG. The operation of the device is the same as that of the conventional example, and heat generated from the electric circuit board 15 and heat transferred through the actuator motor magnet 12b flows into the base 13.
Compared to the outer diameter of the shaft end fixed to the side, the outer diameter of the shaft plate on the opposite side is larger and the thermal resistance is smaller, so the inflow of heat to the cover side increases, causing the base 13 and cover 14 to Temperature differences are reduced and equalized.

Furthermore, in the above example, the spindle shaft 1
7 and the case where the diameter of the end on the cover side of the actuator shaft 19 is larger than the diameter of the end on the base side has been explained. If there are many, the diameter of the shaft end on the base side may be increased.

Example 2. The embodiment of FIG. 2 shows another shaft shape of the same invention. In the figure, the shaft has a tapered and expanding shaft end, and the shape of this shaft end produces the same effect as in the first embodiment. Further, the number of stages may be plural.

Example 3. In the above description, a shaft fixedly supported at both ends has been described, but the same effect can be achieved even when applied to a shaft-rotating spindle or actuator in which both ends of the shaft are supported by rolling bearings or the like.

Example 4. In the second invention, the shape of the shaft, which is somewhat difficult to process into a special shape, remains the same, but the heat resistance of the cover and base that receive the shaft are changed. FIG. 3 shows an example of this.

Example 5. The third invention is one in which the thermal conductivity of a connecting component that connects the shaft, cover, and base is changed. FIG. 4 is a configuration diagram of this embodiment. In the figure, reference numeral 30 denotes a connecting part in which one end of the spindle shaft and the actuator shaft is used to connect the cover to the cover. Reference numeral 32 indicates a connecting part whose other end is used for connecting to the base. The thermal conductivity of material No. 30 is higher than that of material No. 32. Other components are the same as in the example already described.

An embodiment of the third invention will be described below with reference to FIG. The operation of the device is the same as that of the conventional example, and heat generated from the electric circuit board 15 and heat transferred through the actuator motor magnet 12b flows into the base 13.
Since the coupling part 30 of the shaft end on the opposite side has higher thermal conductivity and lower thermal resistance than the coupling part 32 of the shaft end fixed to the side of the cover, the flow of heat into the cover side increases. The temperature difference between the base 13 and the cover 14 is reduced and made uniform.

Furthermore, in the above example, the spindle shaft 7
We have explained the case where the thermal conductivity of the connecting parts on the cover side of the actuator shaft 9 is higher than the thermal conductivity of the connecting parts on the base side. If there is a large amount of heat flowing into the shaft, the thermal conductivity of the shaft end connecting part on the base side may be increased.

Example 6. FIG. 5 is a diagram showing another embodiment of the third invention. As shown in the figure, even when the respective shaft ends are connected via a connecting part embedded in the base or cover, the same effect as in Example 5 can be achieved by changing the thermal conductivity.

Example 7. In the above description, a shaft fixedly supported at both ends has been described, but the same effect can be achieved even when applied to a shaft-rotating spindle or actuator in which both ends of the shaft are supported by rolling bearings or the like.

Example 8. In the above, an example was explained in which joints with different thermal conductivities were applied to both the spindle shaft and the actuator shaft, but even when applied to either the spindle shaft or the actuator shaft, depending on the heat distribution, Similar effects can be expected.

[0023]

[Effects of the Invention] As described above, according to the present invention, the temperature difference between the base and the cover that supports the spindle shaft and the actuator shaft is reduced, and the change in the distance between the magnetic disk and the magnetic head due to the shaft position is reduced. , which has the effect of reducing off-track.

[Brief explanation of drawings]

FIG. 1 is a structural diagram of a magnetic disk device that is an embodiment of the present invention.

FIG. 2 is a structural diagram of a magnetic disk device according to another embodiment of the present invention.

FIG. 3 is a structural diagram of a magnetic disk device that is an embodiment of the second invention.

FIG. 4 is a structural diagram of a magnetic disk device that is an embodiment of the third invention.

FIG. 5 is a structural diagram of a magnetic disk device according to another embodiment of the third invention.

6 is a diagram showing the flow of heat in the magnetic disk device of FIG. 1. FIG.

7 is a diagram showing the flow of heat in the magnetic disk device of FIG. 4. FIG.

FIG. 8 is a structural diagram of a conventional magnetic disk device.

FIG. 9 is a diagram showing the flow of heat in a conventional magnetic disk device.

FIG. 10 is a diagram showing positional displacement due to heat in a conventional magnetic disk device.

[Explanation of symbols]

1 Magnetic disk 2 Magnetic head 11 Actuator/motor/coil 17 Spindle shaft 19 Actuator shaft 23 Base 24 Cover 30 Connecting parts (high thermal conductivity) 32 Connecting parts (low thermal conductivity)

Claims (3)

[Claims] 1. A magnetic disk, a spindle motor for rotating the magnetic disk, a magnetic head, an actuator for driving the magnetic head, a cover and base that accommodate the above mechanisms, and a circuit for operating the device. In a magnetic disk device consisting of a substrate, the shape of at least one of the spindle shaft or actuator shaft that is in contact with the cover and the base is such that a heating element is mounted on the side where a heating element such as a circuit board or a coil is not mounted. A magnetic disk device characterized by having a shaft diameter larger than that of the shaft on which it is attached. 2. A magnetic disc, a spindle motor for rotating the magnetic disc, a magnetic head, an actuator for driving the magnetic head, a cover and base that accommodate the above mechanisms, and a circuit for operating the device. In a magnetic disk device consisting of a substrate, the heat transfer shape of the cover and base that support the spindle shaft and actuator shaft from both sides is determined by the size or size of the heat transfer portion that supports the side on which no heating element such as a circuit board or coil is mounted. Thickness,
A magnetic disk device characterized by being larger or thicker than the size or thickness of the heat transfer portion on the side where the heating element is mounted. 3. A magnetic disk, a spindle motor for rotating the magnetic disk, a magnetic head, an actuator for driving the magnetic head, a cover and base that accommodate the above mechanisms, and a circuit for operating the device. In a magnetic disk device consisting of a circuit board, the thermal conductivity of the coupling parts that connect to the cover and base that support both ends of the spindle shaft or actuator shaft should be set to a value that generates less heat than that of the side on which heat generating elements such as circuit parts are mounted. A magnetic disk device characterized in that the value on the side where the body is not mounted is increased.