Patent Application
20090323221
This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2008-170434, filed Jun. 30, 2008, the entire contents of which are incorporated herein by reference.
1. Field
An embodiment of the invention relates to a head stack assembly used in a disk drive unit provided with a disk recording medium and a disk drive unit provided with the same.
2. Description of the Related Art
In recent years, disk drive units, such as magnetic disk devices, optical disc devices, etc., have been widely used as external recording devices of computers or image recording apparatuses.
A magnetic disk device, e.g., a hard disk drive (HDD), is generally provided with a magnetic disk or disks, spindle motor, magnetic heads, head stack assembly, voice coil motor, board unit, etc. The spindle motor rotates the magnetic disk. The magnetic head reads and writes data from and to the disk. The head stack assembly supports the head. The voice coil motor drives the head stack assembly. These elements are contained in a substantially sealed housing.
As disclosed in Jpn. Pat. Appln. KOKAI Publication No. 5-151724, for example, a head stack assembly is provided with a bearing unit, head gimbal assemblies (HGAs) laminated to the bearing unit, coil assembly, spacer, washer, nut, etc. Each HGA includes an arm extending from the bearing unit, a suspension extending from the arm, and a head attached to the suspension by means of a gimbal portion. A plurality of arms are fixed in layers to the bearing unit with spacers between them. The coil assembly is provided with a support frame that extends from the bearing unit oppositely from the HGAs and supports a coil of a voice coil motor.
Each magnetic disk is provided with two HGAs for its obverse and reverse surfaces. In a disk drive unit that uses two magnetic disks, for example, a head stack assembly is composed of four HGAs that are stacked in layers on a bearing unit with spacers between them.
If the voice coil motor is driven, the head stack assembly rocks around the bearing unit, whereupon the magnetic head is moved to and positioned in a region over a desired track of the magnetic disk.
In the head stack assembly constructed in this manner, the individual components are stacked around the bearing unit, and their respective metal parts directly contact one another. Therefore, if the bearing unit vibrates along its axis, for example, this vibration is transmitted in succession from the bearing unit to the arm, spacer, and suspension. Alternatively, the vibration of the bearing unit is transmitted to the nut, washer, arm, coil assembly, and suspension in the order named. Thus, vibrations of the individual components that constitute the head stack assembly are transferred between the components, so that the entire head stack assembly vibrates. If the vibration is transmitted to the suspension, the positioning accuracy of the magnetic heads is reduced, thereby causing problems such as reduction in read/write performance, occurrence of write errors, etc.
If the bearing unit is subjected to a heavy impact through the housing, moreover, the impact may be transmitted to the suspension and the magnetic heads, thereby damaging the head stack assembly and the magnetic disks.
A general architecture that implements the various features of the invention will now be described with reference to the drawings. The drawings and the associated descriptions are provided to illustrate embodiments of the invention and not to limit the scope of the invention.
Various embodiments according to the invention will be described hereinafter with reference to the accompanying drawings. In general, according to one embodiment of the invention, a head stack assembly comprises stack members stacked on a bearing unit; a suspension and a head on one of the stack members; and an elastic member being between the stack members to damp vibration when there is the vibration which is transmitted from the bearing unit to the stack members.
An HDD according to a first embodiment of this invention will now be described in detail with reference to the accompanying drawings.
The housing 10 contains two magnetic disks 16 for use as recording media and a spindle motor 18 as a drive section that supports and rotates the magnetic disks. The spindle motor 18 is located on the bottom wall 12a. The housing 10 is formed to be large enough to accommodate a plurality of, e.g., two, magnetic disks, and the spindle motor 18 is configured to support and drive two magnetic disks.
Each magnetic disk 16 is formed with a diameter of, for example, 65 mm (2.5 inches) and has magnetic recording layers on its upper and lower surfaces, individually. The disks 16 are coaxially fitted on a hub (not shown) of the spindle motor 18 and clamped and fixed on the hub by a clamp spring 23. Thus, the disks 16 are supported parallel to the bottom wall 12a of the base 12. The disks 16 are rotated at a predetermined speed of, for example, 5,400 or 7,200 rpm by the spindle motor 18.
The housing 10 further contains magnetic heads 17, head stack assembly (HSA) 22, voice coil motor (VCM) 24, ramp load mechanism 25, latch mechanism 26, and board unit 21. The magnetic heads 17 record and reproduce information on and from the magnetic disks 16. The HSA 22 supports the heads 17 for movement with respect to the disks 16. The VCM 24 rocks and positions the HSA 22. The ramp load mechanism 25 holds the magnetic heads in a retracted position at a distance from the magnetic disks when the heads are moved to the outermost peripheries of the disks. The latch mechanism 26 holds the HSA in its retracted position when the HDD is jolted. The board unit 21 includes a preamplifier and the like.
A printed circuit board (not shown) is screwed to the outer surface of the bottom wall 12a of the base 12. The circuit board controls the operations of the spindle motor 18, VCM 24, and magnetic heads through the board unit 21. A circulation filter 19 is disposed on the sidewall of the base 12 and situated outside the magnetic disks 16. The filter 19 captures dust that is produced in the housing when a moving part is operated. Further, a breathing filter 27 is disposed on the sidewall of the base 12. The filter 27 captures dust from air that flows into the housing 10.
The bearing unit 28 is situated apart from the center of rotation of each magnetic disk 16 along the length of the base 12 and near the outer peripheral edge of the disk. The bearing unit 28 includes a pivot 32 set up on the bottom wall 12a of the base 12 and a cylindrical sleeve 36 coaxially supported for rotation on the pivot by a bearing 34. An annular flange 37 is formed on the upper end of the sleeve 36 that functions as a bearing body, while a thread portion 38 is formed on the outer periphery of its lower end portion.
Each HGA 30 includes an arm 40 extending from the bearing unit 28, a suspension 42 extending from the arm, and the magnetic head 17 supported on an extended end of the suspension by a gimbal portion.
The arm 40 is a thin flat plate formed by laminating, for example, stainless steel, aluminum, and stainless steel layers to one another. A circular through-hole 41 is formed in one end or a proximal end of the arm 40. Further, the arm 40 has a lug protruding from its proximal end, and a positioning hole 47 is formed in the lug. The suspension 42 is formed of an elongated leaf spring, and its proximal end is fixed to the distal end of the arm 40 by spot welding or adhesive bonding and extends from the arm. The suspension 42 and the arm 40 may be formed integrally of the same material.
Each magnetic head 17 includes a substantially rectangular slider and a magnetoresistive (MR) read/write head formed on the slider and is fixed to the gimbal portion formed on the distal end portion of the suspension 42. Further, the magnetic head 17 includes four electrodes (not shown). A relay flexible printed circuit board (FPC) 43 is set on the arm 40 and the suspension 42. The magnetic head 17 is electrically connected to a main FPC 21b (mentioned later) through the relay FPC.
The spacer rings 44 and 45 are each provided with a through-hole through which the sleeve 36 of the bearing unit 28 can be passed. The rings 44 and 45 are formed of aluminum or the like and each have a predetermined thickness and a predetermined outside diameter. Each of the spacer rings 44 and 45 includes a lug on the outside, and a positioning hole 39 is formed in the lug. A plastic support frame 46 is molded integrally with the one spacer ring 45 so as to extend outward from the ring 45. A voice coil 49 of the VCM 24 is fixed to the support frame 46.
The annular washer 56 has a through-hole through which the sleeve 36 of the bearing unit 28 can be passed. The washer 56 is formed of aluminum or the like and has a predetermined thickness and a predetermined outside diameter. The washer 56 includes a lug on the outside, and a positioning hole 61 is formed in the lug.
The four HGAs 30 and the two spacer rings 44 and 45 are fitted on the sleeve 36 of the bearing unit 28 that is passed through the respective through-holes of the spacer rings 44 and 45, and are stacked in layers on the flange 37 along the axis of the sleeve. The spacer rings 44 and 45 are fitted on the sleeve 36 in such a manner that they are sandwiched between the two adjacent upper arms 40 and between the two adjacent lower arms 40, respectively. Further, the annular washer 56 is fitted on the lower end portion of the sleeve 36.
The four arms 40, spacer rings 44 and 45, and washer 56 that are fitted on the sleeve 36 are sandwiched between the flange 37 and the nut 58, which is threadedly fitted on the thread portion 38 of the sleeve 36, and are fixedly held on the outer periphery of the sleeve.
A positioning screw 62 is passed through the respective positioning holes 47 of the four arms 40 and the respective positioning holes 39 of the spacer rings 44 and 45 and screwed into the positioning hole 61 of the washer 56 from above. Further, a positioning screw 64 is passed through the four arms 40 and the spacer ring 44 and screwed into the spacer ring 45. Thus, the four arms 40 and the spacer rings 44 and 45 are positioned relatively to one another with respect to the circumference of the sleeve 36.
The four arms 40 extend in the same direction from the sleeve 36, and the arms 40 and the suspensions 42 are rockable integrally with the sleeve 36. The two upper arms 40 are situated parallel to each other across a predetermined space, and the suspensions 42 and the magnetic heads 17 on the arms are opposed to one another. The support frame 46 that is integral with the spacer ring 45 extends from the bearing unit 28 oppositely from the arms 40.
As shown in
On the outer peripheral side of the sleeve 36, the elastic members 70 are arranged individually between the flange 37 of the sleeve 36 and the uppermost arm 40, between the spacer ring 44 and the arms on the opposite sides thereof, between the two middle arms, between the spacer ring 45 and the arms on the opposite sides thereof, between the lowermost arm and the washer 56, and between the washer and the nut 58.
Further, the stack members are laminated along the axis of the bearing unit 28 in such a manner that their respective metal surfaces are in contact with those of their adjacent stack members. In the present embodiment, the contact surface of each stack member is formed with a substantially annular receiving groove 74 around the bearing unit 28. Each elastic member 70 is located between each two adjacent stack members in such a manner that it is received in the respective receiving grooves 74 of the stack members.
As shown in
When the HSA 22 constructed in this manner is incorporated in the base 12, as clearly shown in
As shown in
The ramp load mechanism 25 includes a ramp 66 and tabs 67. The ramp 66 is provided on the bottom wall 12a of the base 12 and located outside the magnetic disks 16. The tabs 67 extend individually from the respective distal ends of the suspensions 42. As the HSA 22 turns around the bearing unit 28 so that each magnetic head 17 is moved to its retracted position outside the magnetic disks 16, each tab 67 engages with a ramp surface formed on the ramp 66 and is then pulled up along the slope of the ramp surface. Thereupon, the magnetic heads 17 are unloaded from the magnetic disks 16 and held in the retracted position.
According to the HDD constructed in this manner, each magnetic disk 16 is rotated at high speed during operation. If the voice coil 49 is energized, the HSA 22 rocks around the bearing unit 28, whereupon each magnetic head 17 is moved to and positioned in a region over a desired track of the magnetic disk 16. Thus, the head 17 can perform information processing, that is, write or read information to or from the disk 16.
According to the HDD described above, the HSA 22 is provided with the elastic members 70 that are sandwiched between the adjacent stack members. If the base 12 or the bearing unit 28 is vibrated, therefore, the elastic members 70 between the stack members can damp vibration transmitted from the bearing unit to the stack members. According to the present embodiment, the elastic members 70 are arranged individually between the flange 37 of the sleeve 36 and the uppermost arm 40, between the spacer ring 44 and the arms on the opposite sides thereof, between the two middle arms, between the spacer ring 45 and the arms on the opposite sides thereof, between the lowermost arm and the washer 56, and between the washer and the nut 58. As the vibration is transmitted, therefore, it is gradually damped by means of the elastic members 70. Thus, the vibration transmitted to the suspensions 42 and the magnetic heads 17 is reduced. In consequence, the head positioning accuracy can be improved, so that the read/write performance during the application of vibration can be enhanced, and a reduction in the incidence of write errors can be expected. As the positioning accuracy for the magnetic heads is improved, moreover, the recording capacity of the magnetic disks can be increased.
Also if impact, not vibration, is applied to the base 12 and the bearing unit 28, the elastic members 70 can reduce the impact peak in the same manner as aforesaid. In consequence, the members can be prevented from being damaged.
Further, the stack members are laminated with their respective metal surfaces in contact with one another, and the elastic members are located in the receiving grooves of the stack members. Therefore, a vibration-damping effect can be obtained while maintaining the stack height of the HSA 22 with high accuracy.
Thus, there can be obtained a head stack assembly, capable of damping or reducing vibration and impact and improving head positioning accuracy and reliability, and a disk drive unit provided with the same.
The following is a description of an HSA 22 of an HDD according to a second embodiment of this invention.
More specifically, a plurality of stack members, including four arms 40, spacer rings 44 and 45, a washer 56, and a nut 58, are fitted in layers on a sleeve 36 of a bearing unit 28. As shown in
Other configurations of the HSA 22 and the HDD of the second embodiment are the same as those of the foregoing first embodiment, so that a detailed description thereof is omitted.
According to the second embodiment constructed in this manner, the elastic members that are provided between the bearing unit 28 and the stack members can damp vibration transmitted radially from the bearing unit to the stack members. Thus, the vibration transmitted to suspensions 42 and magnetic heads 17 is reduced. In consequence, the head positioning accuracy can be improved, so that the read/write performance during the application of vibration can be enhanced, and a reduction in the incidence of write errors can be expected. As the positioning accuracy for the magnetic heads is improved, moreover, the recording capacity of magnetic disks can be increased. Further, the same functions and effects as those of the first embodiment can be obtained.
While certain embodiments of the invention have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the invention. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms. Furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the invention. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the invention.
In the foregoing first embodiment, for example, the HSA is configured so that the elastic members are provided between all the adjacent stack members. However, a vibration-damping effect can be obtained if an elastic member is sandwiched between at least a pair of adjacent stack members. Further, a plurality of elastic members, instead of one, may be provided between each two adjacent stack members. In the second embodiment, the HSA is configured so that the elastic members are provided individually between the bearing unit and all the stack members except the nut. However, a vibration-damping effect can be obtained if an elastic member is sandwiched between at least one stack member and the bearing unit. Each elastic member is not limited to the annular shape and may be of, for example, a split shape.
In the embodiments described above, the receiving grooves are formed individually in the respective contact surfaces of each two adjacent stack members. Alternatively, however, a receiving groove may be formed in at least one of the contact surfaces so that an elastic member is received in the groove. Further, the receiving grooves may be omitted so that elastic members are located directly between the contact surfaces of stack members.
Although the disk drive that can be loaded with two magnetic disks has been described in connection with each of the foregoing embodiments, the present invention is also applicable to a disk drive that is provided with one or three or more magnetic disks and a head stack assembly therefor. Further, the materials of the components of the HSA can be variously selected without being limited to the embodiments described herein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2008-170434 | Jun 2008 | JP | national |
