JPS60251571A - Magnetic disk unit - Google Patents

Abstract

PURPOSE:To lock a head associatively with power on-off operation and to prevent a head crush accident, etc., due to external force easily and securely by composing a locking mechanism of a bidirectional shape memory alloy and a heating body and restraining the motion of a head positioning mechanism by the locking mechanism. CONSTITUTION:When the power source is turned on, the heat of the heating body 22 of the locking mechanism 20 is conducted and bidirectional shape memory alloy 21 deforms from a broken-line position to a solid-line position, so that its tip releases a head position mechanism 5. When the power source is turned off, the memory alloy 21 presses a head arm 6 and a sectorial body 9 extended at its opposite side is put in abutting relation to a stopper 13a, locking the head. Thus, the locking mechanism is operated associatively with power on-off operation to prevent a head crush accident due to external force easily and securely.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a magnetic disk drive, and particularly to a head caused by external vibrations, shocks, etc. when the magnetic disk drive is transported or when its disk spindle is stopped. The present invention relates to a magnetic disk device that can easily and reliably prevent crash accidents and the like with a locking mechanism that skillfully utilizes a two-way shape memory alloy.

[Prior art]

In general, this type of magnetic disk device has a function that allows direct access to desired records and has a large storage capacity for information, so it is widely used as a file storage device for computers and the like. Incidentally, in such a magnetic disk device, the actuator that constitutes the head positioning mechanism positions the head on the target track based on the position information written on the disk surface of the magnetic disk that is rotationally driven by a disk rotation system such as a spindle. The magnetic head is positioned by moving the magnetic head, and is configured so that the magnetic head can read and write desired information.

To briefly explain this, for example, the oscillating multi-actuator known as the head positioning mechanism mentioned above holds a plurality of magnetic heads at their tips.
＼ Rad arm, to these - A rotary carriage that holds the 2-door arm and is pivotally supported on a swing shaft, a positioner coil that is integrally installed on this, and magnetic circuit components such as a magnet and yoke that are installed on the fixed side. It is composed of etc. In such a configuration, the rotary carriage equipped with the magnetic head is oscillated around the oscillation axis due to the attraction and repulsion between the positioner coil and the magnet described above, and the magnetic head is moved and positioned. It is something that fulfills a function.

In such magnetic disk drives, a contact start/stop type head/disk assembly consisting of a magnetic disk, its rotational drive mechanism, and the above-mentioned head positioning mechanism has been known. When the disk rotation system is stopped, the magnetic disk and the magnetic head are in contact with each other, so when this head/disk assembly is excited by external vibrations, it forms a head positioning mechanism. The movable part swings and rotates, which may damage the contact area between the magnetic disk and the magnetic head, leading to a risk of a head crash. Therefore, in this type of device, when the disk spindle is stopped or the head/disk assembly is transported, it is necessary to lock and fix the movable part of the head positioning mechanism by some means. method has been adopted. As an example, the most common method is to selectively lock the movable state of the head positioning mechanism from the outside by penetrating the housing cover of the head disk assembly or the base disposed inside the housing cover. Mechanical locking mechanisms are known.

However, with such a mechanically configured locking mechanism, it is virtually impossible to keep the inside of the head/disk assembly dust-free. This has resulted in disadvantages such as the contamination of dust and the tendency of head crashes caused by such dust. In other words, this type of device uses a floating magnetic head that flies above the magnetic disk surface with a minute flying clearance, and it is important to avoid the possibility of small-diameter dust getting into the tiny gap between the head and the disk. In order to prevent this, it is necessary to avoid the ingress of dust into the head-fist disc assembly.

In order to solve this problem, it is necessary to add a dust seal such as an O-ring or a magnetic fluid seal to the take-out portion of the above-mentioned mechanical locking mechanism. However, even with this method, there is a limit to how far it can be made to be dust-free, and in order to obtain a completely airtight structure inside the head disk assembly, measures such as filling helium gas inside the head disk assembly are necessary. Moreover, in such a configuration, the mechanical locking mechanism described above could not be used, and some type of mechanism that operated within an airtight structure had to be installed. As a locking mechanism for a movable part that operates within an airtight structure, it is possible to use a permanent magnet or an electromagnet, for example, but since magnetic attraction is used as a means to lock and fix a movable part in this way In order to do so, the following problems must be resolved.

(1) Since the magnetic attraction force is inversely proportional to the square of the distance, in order to securely fix the movable part, it is necessary to bring the movable part close to a distance where the attraction force effectively works.

(2) If the driving force from the positioner coil is used to obtain such driving force, the movable part locking mechanism may operate during normal operation of the magnetic disk device, especially when the positioner coil is in a runaway state. Otherwise, there is a risk that this locking mechanism will be damaged due to a collision.

Furthermore, as another locking mechanism, there is a configuration using a self-retaining plunger made of a combination of a semi-hard magnetic material and a spring, but this has the disadvantage that its structure is complicated and expensive.

It is also possible to use a unidirectional shape memory alloy that deforms when heated as such a locking mechanism, but such a unidirectional shape memory alloy does not work when cooled. Therefore, in order to perform reversible operation, a separate mechanism for returning to the low temperature state by the force of the bias coil is required, which leads to problems such as a complicated structure.

[Summary of the invention]

The present invention was made in view of these circumstances, and
A locking mechanism that selectively engages with and restricts the movement of the head positioning mechanism that moves the magnetic head along the surface of the magnetic disk to record and reproduce information is made of two-way shape memory alloy. and a heating element,
In addition, this locking mechanism is operated in conjunction with turning on and off the power of the device to lock and release the head positioning mechanism, which is a simple and inexpensive structure. A simple magnetic disk that has the advantage of being able to easily and reliably prevent head crash accidents caused by external vibrations, shocks, etc. when the spindle is stopped, etc. by cleverly utilizing a two-way shape memory alloy. It provides equipment.

〔Example〕

Hereinafter, the present invention will be explained in detail using embodiments shown in the drawings.

FIGS. 1(a) and 1(b) show an embodiment of a magnetic disk device according to the present invention. In this embodiment, the magnetic disk device is of a type having a completely sealed chamber, and a swing type head positioning mechanism is used. A case where a multi-type one is used will be explained.

In these figures, reference numeral 1 denotes a magnetic disk that is a recording medium (in this example, three disks are stacked in parallel at the top and bottom), and these multiple magnetic disks l are , is rotatably supported by being provided on a hub 3 that is integrally fixed to a spindle 2 that is rotationally driven by a motor (not shown), thereby configuring a disk rotation system 4.

Reference numeral 5 denotes a head positioning mechanism comprising a floating magnetic head (not shown) that records and reproduces information by being moved over the disk surface of the above-mentioned magnetic disk 1. A head arm 6 that holds a magnetic head at its tip 6a, a rotary carriage 8 that holds the base of the head arm 6 and is rotatably supported on a swing shaft 7, and the rotary carriage. A positioner coil lO provided on a fan-shaped pobbin 9 extending from 8 to the side opposite to the helad arm 6, and a magnet provided on the base 11 side as a fixed part opposite to this positioner coil lO. It is composed of a magnetic circuit component 12 such as a yoke. According to such a head positioning mechanism 5, the rotary carriage 8 equipped with the magnetic head is moved by attraction and repulsion with the magnet on the magnetic circuit component 12 side according to the current value given to the positioner coil IO described above.
are each swung around the swiveling shaft 7 as the swiveling center as shown by the arrows in the figure, thereby moving the magnetic head in the radial direction of the magnetic disk l via the head arm 6 for its movement and positioning. It is something that fulfills a function.

Here, - the movable part constituting the above-mentioned head positioning mechanism 5 has its swing range restricted by both sides of the magnetic circuit component 12 on the fixed side, and the end portion of the swing range is Stoppers 13a and 13b made of various elastic materials are provided as stopping devices that limit movement beyond the permissible range and also serve to stably stop the magnetic head. This is because when an accidental failure occurs in this type of device, such as an error in reading position information or a drive circuit failure, a so-called runaway operation state occurs in which the movable part moves beyond a predetermined range. This is because the magnetic head and the surface of the magnetic disk 1 may be damaged, causing problems such as their functions being stopped.

The members constituting the disk rotation system 4 and the head positioning mechanism 5 described above are attached to the base 11'2, and together with the base 11, they are formed by a cover 14 that serves as a casing of the disk assembly. It is placed in a sealed chamber. The configuration and operation of this type of head/disk assembly other than those described above are well known, and their explanation will be omitted.

Now, according to the present invention, the locking mechanism 20 selectively engages with the movable part of the head positioning mechanism 5 that moves the magnetic head along the disk surface of the magnetic disk l described above to restrain its movement. As shown in the details in Figure 2,
It is characterized in that it is composed of a two-way shape memory alloy 21 and a heating element 22. By operating this locking mechanism 20 in conjunction with turning on and off the power of the magnetic disk device, the movable portion of the head positioning mechanism 5 can be locked and opened, even though the structure is simple. It is designed to be easily and reliably obtained. In other words, in this type of magnetic disk device,
-M'l of the head/disk assembly as described in
Vibration applied from the outside at 11 o'clock, during storage, and when the disk spindle is stopped after device mounting,
There is a risk of head crash accidents caused by impacts, etc., and the present invention very easily and reliably prevents such problems by skillfully utilizing the characteristics of the two-way shape memory alloy 21. This is how it was done.

To explain this in detail, according to this embodiment, the two continuous two-way shape memory alloys 21 are formed to have a substantially rod shape, and are in the state shown by solid lines and broken lines in FIG. It has a two-way shape memory effect that allows it to memorize its shape so that it can change its shape in response to temperature changes. That is, the two-way shape memory alloy 21 takes the shape shown by the broken line when the temperature is low, and changes its shape as shown by the solid line when the temperature rises. The two-way shape memory alloy 21 is erected on the base 11 with its tip facing the vicinity of the head arm 6, which is the movable part of the head positioning mechanism 5, and is used when the device is stopped when a locked state is required. etc., it has a shape as shown by the broken line in the figure, so that its tip abuts and engages with a plane located within the moving plane of the head arm 6, and this movable part is used as the stopper for stopping the runaway state described above. ) is pressed against one side (13a) of the y-pa to restrict its movement. In addition, 23 in the figure
is a thermal conductor that holds a two-way shape memory alloy 21 and transmits heat from the heating element 22 to the two-way shape memory alloy 21, and the heating element 22 is assembled on the outer periphery of the other end of this thermal conductor 23. It is being In addition, these two-way shape memory alloys 21
The heat conductor 23 is held by a heat insulator 24 made of ceramic or the like while penetrating the base 11. It plays the role of effectively communicating to 21.

According to such a configuration, when power is turned on to the device and at the same time power is supplied to the heating element 22 of the locking mechanism 20 and the heating element 22 is heated, this heat flows through the thermal conductor 23. The heat is transferred to the two-way shape memory alloy 21 through the two-way shape memory alloy 21, and the two-way shape memory alloy 21 deforms as shown by the solid line in FIG. 2, thereby opening the head positioning mechanism 5. Furthermore, when the device power is cut off, the heating element 22 constituting the locking mechanism 20 of the head positioning mechanism 5 is also turned off, which lowers the temperature of this part and causes the two-way shape memory alloy 21 to cool down as shown in FIG. The state shown by the medium broken line is reached, and the head positioning mechanism 5 is engaged and locked.

Here, the two-way shape memory effect by the two-way shape memory alloy 21 as described above occurs based on the martensitic transformation and reverse transformation of the Ti-Ni alloy,
The phase transformation temperature suitable for implementation in this device is as shown in FIG. The temperature at which reverse transformation starts from to the parent phase (A s point)
It has been confirmed through experiments that it is preferable to store the temperature at about 50° C. and the temperature at which the transformation from the martensitic phase to the parent phase ends (A1 point) to about 60° C. or higher.

Note that the present invention is not limited to the structure of the embodiments described above, and the shape and structure of each part may be modified and changed as appropriate. In addition to the swing type head positioning mechanism 5, it can also be applied to a single swing type, a straight type, or a straight type multi-type, and the effects in that case are also the same as those described above. It will be easily understood that this is similar to the example. Furthermore, it is clear that the location of the locking mechanism 20 is not limited to the vicinity of the head arm 6 as in the embodiment, as long as the movable portion of the head positioning mechanism 5 can be restrained.

〔Effect of the invention〕

As explained above, according to the magnetic disk device of the present invention, the magnetic head is selectively engaged with the movable part of the head positioning mechanism that moves the magnetic head along the disk surface of the magnetic disk to record and reproduce information. A locking mechanism is constructed of a two-way shape memory alloy and a heating element, and this locking mechanism is operated in conjunction with turning on and off the power of the device to lock the head positioning mechanism. Despite its simple and inexpensive configuration, this type of device, especially when transporting and storing the head/disk assembly, as well as when stopping the disk spindle after the device is installed, is protected against external damage. It has various excellent effects, such as being able to very easily and reliably prevent head crash accidents caused by applied vibrations, shocks, etc. by skillfully utilizing the properties of the two-way shape memory alloy.

[Brief explanation of drawings]

FIGS. 1(a) and 1(b) are a schematic side sectional view and knee plan view showing an embodiment of the magnetic disk device according to the present invention, and FIG. 2 is an enlarged view of the locking mechanism, which is a feature of the device. The main part sectional view and FIG. 3 are characteristic diagrams of a two-way shape memory alloy suitable for application to the device of the present invention. l...Magnetic disk, 2, φ...Spindle, 3-
...Fist hub, 4...Disc rotation system 5...Head positioning mechanism, 6...Head arm, 7.11φ
・Swing axis, 8...Rotary carriage, lO...
Working positioner coil, 11... base, 12... magnetic circuit component, 13a, 13b... stopper, 14... pot/cover, 20 meeting... locking mechanism, 21
... Two-way shape memory alloy, 22 ... Heating element, 2
3... Heat conductor, 24... Heat insulator. Patent applicant: Nippon Telegraph and Telephone Public Corporation Agent: Kazuki Yamakawa (and 1 other person) Figure 1 (a) Figure 1 (b)

Claims (1)

[Claims] In a magnetic disk drive equipped with a head positioning mechanism for recording and reproducing information by moving a magnetic head along the disk surface of a magnetic disk, the head positioning mechanism selectively engages with a movable part of the head positioning mechanism to A magnetic disk device characterized in that a locking mechanism for restricting movement is constructed of a two-way shape memory alloy and a heating element.