Manufacturing method for magnetic disk device and magnetic disk device

Abstract

To provide a manufacturing method for a magnetic disk device and a magnetic disk device to ensure the design margin of the magnetic disk device.SOLUTION: A manufacturing method for a magnetic disk device according to the embodiment includes: adjusting relative heights of a spindle that can rotate and align central axes of a plurality of magnetic disks, whose ends are shifted from a geometric plane as a basis of a center point, and a plurality of ramps that will be respectively positioned at the end points of the plurality of magnetic disks; and assembling the plurality of magnetic disks along the axial direction of the spindle by aligning the shifted direction of the ends from the center point.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] Embodiments of the present invention relate to a method for manufacturing a magnetic disk drive and a magnetic disk drive.

Background Art

[0002] In a magnetic disk drive, a plurality of magnetic disks are assembled in parallel along the axial direction of a spindle that rotates the magnetic disks. In recent years, in order to meet the demand for higher capacity of magnetic disk drives, the magnetic disks have been made thinner and multi-layered. For this reason, the magnetic disks are likely to warp, and it has become difficult to secure a design margin for the magnetic disk drive.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] One embodiment aims to provide a method for manufacturing a magnetic disk drive and a magnetic disk drive that can secure a design margin for the magnetic disk drive.

Means for Solving the Problems

[0005] The manufacturing method of the magnetic disk device according to the embodiment aligns the central axes of a plurality of magnetic disks whose ends are displaced from a geometric plane with reference to a center point, and adjusts the relative heights of a spindle that can rotate and a plurality of lamps that are respectively arranged at the end positions of the plurality of magnetic disks, aligns the displacement directions of the ends from the center point, and assembles the plurality of magnetic disks along the axial direction of the spindle.

Brief Description of the Drawings

[0006]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Embodiments for Carrying Out the Invention

[0007] Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited by the following embodiments. Also, the constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same.

[0008] (Example of the Configuration of a Magnetic Disk Device) FIG. 1 is a schematic diagram showing an example of the configuration of a magnetic disk device 10 according to an embodiment. The magnetic disk device 10 of the embodiment is configured as, for example, an HDD (Hard Disk Drive). However, the magnetic disk device 10 of the embodiment may be another magnetic disk device such as a hybrid HDD.

[0009] As shown in FIG. 1, the magnetic disk device 10 of the embodiment includes a spindle motor (SPM) 11, a plurality of magnetic disks 12, a plurality of magnetic heads 13, an actuator unit 14, a head amplifier 16, a SoC (System on Chip) 17, and a servo controller (SVC) 18.

[0010] The spindle motor 11 has a spindle 19 that serves as a rotation axis. A plurality of magnetic disks 12 are held on the spindle 19 by means such as clamping. The spindle motor 11 rotates the plurality of magnetic disks 12 integrally around the spindle 19. Recording surfaces on which data can be recorded are formed on both sides of the plurality of magnetic disks 12.

[0011] A plurality of magnetic heads 13 are provided in proximity to the recording surfaces on both sides of each of the individual magnetic disks 12 so as to be able to access the recording surfaces of these magnetic disks 12 respectively. That is, the number of magnetic heads 13 is set to correspond to, for example, the number of recording surfaces of the magnetic disks 12. Each of the plurality of magnetic heads 13 can perform data recording and data reproduction with respect to the corresponding recording surface of the magnetic disk 12.

[0012] Each of the plurality of magnetic heads 13 is provided so as to be able to face the recording surface of the corresponding magnetic disk 12. Each of the plurality of magnetic heads 13 can perform data recording and data reproduction with respect to the recording surface of the magnetic disk 12 that the magnetic head 13 faces.

[0013] The actuator unit 14 includes a plurality of suspensions 21, a plurality of actuator arms 22, a rotation axis 23, a voice coil motor (VCM) 24, and a plurality of micro actuators (MA) 25.

[0014] The number of suspensions 21, actuator arms 22, and micro actuators 25 is set to correspond to the number of magnetic heads 13. The rotation axis 23 of the actuator unit 14 is provided at a position separated from the spindle 19 of the spindle motor 11 and substantially parallel to the spindle 19.

[0015] Each of the plurality of suspensions 21 is configured in a plate shape that can be elastically deformed. Each of the plurality of suspensions 21 supports a corresponding one of the plurality of magnetic heads 13 near the tip.

[0016] One end of each of the plurality of actuator arms 22 is rotatably supported by a rotating shaft 23 so as to be rotatable around the rotating shaft 23. One corresponding one of the plurality of suspensions 21 is attached to each other end of the plurality of actuator arms 22.

[0017] The micro actuator 25 is provided at a connection portion between the suspension 21 and the actuator arm 22. The micro actuator 25 is an actuator element such as a piezoelectric element, for example. The micro actuator 25 can move the suspension 21 substantially parallel to the recording surface of the magnetic disk 12.

[0018] The voice coil motor 24 can rotate the actuator arm 22 around the rotating shaft 23 to move the magnetic head 13 supported by the suspension 21 relative to the magnetic disk 12. Note that the actuator unit 14 may include a plurality of voice coil motors 24.

[0019] As described above, the actuator unit 14 is configured as a two-stage actuator that moves the magnetic head 13 by the voice coil motor 24 and the micro actuator 25.

[0020] The head amplifier 16 amplifies a signal read by the magnetic head 13 from the magnetic disk 12 and outputs it to the SoC 17. The SoC 17 demodulates the signal output from the head amplifier 16 into digital data by a read channel circuit.

[0021] Also, a signal corresponding to digital data is supplied from the SoC 17 to the head amplifier 16. The head amplifier 16 amplifies the signal supplied from the SoC 17 and supplies it to the magnetic head 13. The magnetic head 13 records the signal supplied from the head amplifier 16 on the recording surface of the magnetic disk 12.

[0022] The servo controller 18 controls the voice coil motor 24 and the micro actuator 25 of the actuator unit 14. That is, the servo controller 18 positions the magnetic head 13 at the position instructed by the SoC 17 by driving the actuator unit 14 based on the instruction from the SoC 17.

[0023] More specifically, the servo controller 18 applies a voltage corresponding to the instructed value of the drive voltage of the voice coil motor 24 to the voice coil motor 24, and applies a voltage corresponding to the instructed value of the drive voltage of the micro actuator 25 to the micro actuator 25. Thereby, the magnetic head 13 is positioned at the target position.

[0024] Also, the servo controller 18 drives the spindle motor 11 based on the instruction from the SoC 17. The servo controller 18 drives the spindle motor 11 so that the rotational speed of the spindle motor 11 becomes constant at a predetermined target speed.

[0025] Also, the servo controller 18 retracts the magnetic head 13 when the power supply to the magnetic disk device 10 is cut off. The servo controller 18 may retract the magnetic head 13 when a seek error occurs in the positioning control of the magnetic head 13.

[0026] The SoC 17 has an MPU (Micro-Processing Unit) 17a. The MPU 17a operates according to a firmware program. The firmware program is stored in a predetermined non-volatile storage area. The predetermined non-volatile storage area may be the magnetic disk 12 or the ROM (Read Only Memory) of the SoC 17.

[0027] The MPU 17a controls the operation of the entire magnetic disk drive 10. For example, the MPU 17a controls access to the magnetic disk 12 using the magnetic head 13 via the head amplifier 16. Also, the MPU 17a instructs the servo controller 18 to control the rotation of the spindle motor 11, or executes load / unload control of the actuator unit 14 via the servo controller 18.

[0028] Also, in the positioning control, the MPU 17a calculates an instruction value of the drive voltage of the voice coil motor 24 and an instruction value of the drive voltage of the micro actuator 25 in order to cause the position of the magnetic head 13 to follow the target position. The MPU 17a calculates each instruction value using, as a feedback input, a position signal read from the servo information formed on the recording surface of the magnetic disk 12 by the magnetic head 13, and transmits each obtained instruction value to the servo controller 18.

[0029] The SoC 17 configured in this way is electrically connected to the host 2 and can receive access commands (for example, read commands and write commands) from the host 2. The SoC 17 interprets the access commands from the host 2 and, based on the interpretation result, executes various controls such as access to the magnetic disk 12 as described above.

[0030] The SoC 17 and the host 2 communicate via a communication line using, for example, a communication protocol compliant with the SAS (Serial Attached SCSI) standard. However, the standard of the communication line between the SoC 17 and the host 2 is not limited to this example.

[0031] The host 2 is configured as, for example, a processor, a personal computer, or a server.

[0032] FIG. 2 is a top view schematically showing a partial configuration of the magnetic disk drive 10 according to the embodiment. FIG. 2 shows a state of a spindle motor (SPM) 11, a plurality of magnetic disks 12, a plurality of magnetic heads 13, and an actuator unit 14 inside the housing of the magnetic disk drive 10 as viewed from above.

[0033] As shown in FIG. 2, the actuator unit 14 can move the magnetic head 13 along a track T with respect to the recording surface of the magnetic disk 12 by a voice coil motor 24 and a micro actuator 25. A ramp load mechanism 15 is provided on the track T near the outer end of the magnetic disk 12.

[0034] The voice coil motor 24 rotates the actuator arm 22 and the suspension 21 attached to the actuator arm 22 in an arc shape within a predetermined range around the rotation axis 23. At this time, the voice coil motor 24 moves the actuator arm 22 substantially parallel to the recording surface of the magnetic disk 12. That is, the voice coil motor 24 moves the magnetic head 13 in a radial direction substantially orthogonal to the spindle 19 with respect to the magnetic disk 12.

[0035] Thereby, the magnetic head 13 can be moved on the tracks D1 and D2 between the ramp load mechanism 15 and the spindle 19.

[0036] The ramp load mechanism 15 is provided near the end position of the magnetic disk 12, and the magnetic head 13 is loaded / unloaded with respect to the magnetic disk 12 via the ramp load mechanism 15.

[0037] As described above, the magnetic disk drive 10 has a configuration in which a plurality of magnetic disks 12 are assembled in parallel along the axial direction of the spindle 19. The plurality of magnetic disks 12 are being thinned and are in a state where warping is likely to occur. In the magnetic disk drive 10 of the embodiment, these magnetic disks 12 are assembled to the spindle 19 with their warping directions aligned for each magnetic disk 12 whose warping amount is within a predetermined range.

[0038] Here, the magnetic disk 12 often has a warp such that the whole presents a bowl shape. That is, the amount of warp of the magnetic disk 12 can be represented by, for example, the amount of deviation (displacement amount) from the geometric plane at the end of the magnetic disk 12 with reference to the center point of the magnetic disk 12. At this time, for example, the amount of deviation can be measured for a plurality of ends of the magnetic disk 12, and the maximum value of these can be used as the amount of deviation. Alternatively, the average value of the amounts of deviation measured for the plurality of ends may be used as the amount of deviation.

[0039] Hereinafter in this specification, with reference to the center point of the magnetic disk 12, the amount of deviation from the geometric plane at the end of the magnetic disk 12 is referred to as the flatness of the magnetic disk 12.

[0040] Examples of the case where the magnetic disk 12 with flatness below a predetermined value is assembled and the case where the magnetic disk 12 with flatness within a predetermined range is assembled are shown in FIGS. 3 and 4 below.

[0041] FIG. 3 is a schematic diagram showing an example of the case where the magnetic disk 12f with flatness below a predetermined value is assembled in the magnetic disk device 10 according to the embodiment. FIG. 3(a) shows the whole of a plurality of magnetic disks 12f assembled to the spindle 19. FIG. 3(b) shows an enlarged cross section of the ramp load mechanism 15 provided near the ends of the plurality of magnetic disks 12f.

[0042] The magnetic disk device 10 shown in FIG. 3 includes a plurality of magnetic disks 12f. All of these magnetic disks 12f have flatness below a predetermined value, and the amount of deviation of the ends from the geometric plane with reference to the center point is substantially zero. That is, the magnetic disk 12f has almost no warp and has a substantially flat shape.

[0043] As shown in FIG. 3, a hub 191 that forms the shaft portion of the spindle 19 is provided on the spindle motor 11 of the magnetic disk device 10, and a plurality of magnetic disks 12f are each assembled to the hub 191 at substantially equal intervals via spacers 192. A clamp 193 is placed over and tightened on the upper end of the hub 191 to which the magnetic disk 12f is assembled, whereby the plurality of magnetic disks 12f are assembled to the spindle 19 having the hub 191, spacers 192, clamp 193, etc.

[0044] A ramp load mechanism 15 is provided near the end of the magnetic disk 12f at a predetermined distance from the spindle 19. The ramp load mechanism 15 includes a plurality of ramps 151. These ramps 151 have grooves into which the ends of the magnetic disks 12f are inserted in a non-contact manner, and are installed at substantially equal intervals in the vertical direction so as to correspond to the individual magnetic disks 12f.

[0045] Each of the plurality of magnetic disks 12f has an end at a substantially central portion in the vertical direction within the groove of the corresponding ramp 151. That is, the ends of the individual magnetic disks 12f are inserted into the grooves while maintaining a substantially equal distance from the upper and lower surfaces of the grooves. These distances are also maintained substantially uniformly among the plurality of magnetic disks 12f.

[0046] The above-described magnetic head 13 is housed in the ramp load mechanism 15 and is loaded / unloaded with respect to the magnetic disk by moving back and forth on the ramp 151 provided near the end of the corresponding magnetic disk 12f.

[0047] As described above, in the magnetic disk device 10 of the embodiment, the initial relative height between the spindle 19 and the plurality of ramps 151 is optimized for the case where a substantially flat magnetic disk 12 is assembled.

[0048] FIG. 4 is a schematic diagram showing an example in the case where the magnetic disk 12c with flatness within a predetermined range is assembled in the magnetic disk device 10 according to the embodiment. FIG. 4(a) shows the entirety of a plurality of magnetic disks 12c assembled to the spindle 19. FIG. 4(b) shows an enlarged cross-section of the ramp load mechanism 15 provided near the ends of the plurality of magnetic disks 12c.

[0049] The magnetic disk device 10 shown in FIG. 4 includes a plurality of magnetic disks 12c. All of these magnetic disks 12c have flatness greater than that of the magnetic disk 12f shown in FIG. 3 above and are within a predetermined range. That is, the magnetic disk 12c has a predetermined amount of warpage and has an overall bowl-shaped configuration.

[0050] As shown in FIG. 4, these magnetic disks 12c are assembled to the spindle 19 of the magnetic disk device 10 with the deviation directions of the ends from the center point aligned. In the example of FIG. 4, the magnetic disks 12c are assembled to the spindle 19 such that the deviation directions of the ends from the center point are downward in all the magnetic disks 12c, that is, in a direction such that all the magnetic disks 12c have an upward convex shape like an overturned bowl.

[0051] The configurations such as the spindle 19 and the ramp load mechanism 15 shown in FIG. 4 are housed within a housing (both not shown) in which the top cover and the base member are joined. More specifically, the spindle 19, the ramp load mechanism 15, etc. are installed on the base member of the housing of the magnetic disk device 10 and are covered by the top cover. In this specification, the top cover side is taken as the upward direction of the magnetic disk device 10, and the base member side is taken as the downward direction of the magnetic disk device 10.

[0052] As described above, when the magnetic disk 12c is assembled such that the displacement direction of the end portion from the center point is downward, with respect to the magnetic disk device 10, the displacement direction of the end portion of the magnetic disk 12c may be referred to as the base member direction. That is, in the magnetic disk device 10 shown in FIG. 4, the end portion of the magnetic disk 12c has a predetermined displacement amount (displacement) in the base member direction from the center point of the magnetic disk 12c.

[0053] Also, on the spindle motor 11, that is, at the lower end portion of the hub 191 of the spindle 19, a donut-shaped shim 11s having a predetermined thickness is inserted. As a result, the entire spindle 19 and the plurality of magnetic disks 12c assembled to the spindle 19 are raised upward by the thickness of the shim 11s.

[0054] Here, the magnetic disk 12 includes those made of aluminum and those made of glass. When the magnetic disk 12 is made of aluminum, usually, the spindle 19 including the hub 191 and the like is also made of aluminum. Therefore, it is preferable that the material of the shim 11s is also aluminum. Also, when the magnetic disk 12 is made of glass, a spindle 19 including the hub 191 and the like is made of SUS. Therefore, it is preferable that the material of the shim 11s is also SUS.

[0055] When a plurality of magnetic disks 12c are assembled to the spindle 19 in a shape like an inverted bowl, for example, if the relative height between the spindle 19 and the magnetic disks 12c and the lamp loading mechanism 15 remains as shown in FIG. 3, the end portions of these magnetic disks 12c will shift downward within the groove of the corresponding lamp 151, and the distance from the lower surface of the groove will be closer than the distance from the upper surface. The dashed line in FIG. 4(b) shows such a state of the magnetic disk 12c. Such a state reduces the contact margin between the magnetic disk 12c and the lamp 151 and increases the risk of their contact.

[0056] In the magnetic disk drive 10 of the embodiment, as described above, the shim 11s is inserted into the lower end of the spindle 19 to raise the spindle 19 and the magnetic disk 12c. As a result, the relative height between the spindle 19 and the magnetic disk 12c and the ramp load mechanism 15 is adjusted, and the ends of the individual magnetic disks 12f are inserted into the grooves while maintaining a distance substantially equal to the upper and lower surfaces of the grooves of the corresponding ramp 151. These distances are maintained substantially uniformly among the plurality of magnetic disks 12c.

[0057] Also, when the magnetic disk 12c is made of aluminum, the shim 11s is also made of aluminum, and when the magnetic disk 12c is made of SUS, the shim 11s is made of SUS, so that their coefficients of thermal expansion can be made substantially equal. Therefore, the contact risk due to thermal expansion between the mutual members such as the magnetic disk 12c, the spindle 19, and the shim 11s can be reduced.

[0058] (Method of manufacturing a magnetic disk drive) Next, an example of a method of manufacturing the magnetic disk drive 10 of the embodiment will be described with reference to FIGS. 5 to 8.

[0059] As described above, the magnetic disk 12 has been thinned and is in a state where warping is likely to occur. Each magnetic disk 12 has a different flatness due to manufacturing tolerances and the like. Therefore, at the time of manufacturing the magnetic disk 12, after the polishing process, the flatness of each magnetic disk 12 is measured by a 100% inspection using a flatness measuring machine or the like.

[0060] FIG. 5 is a schematic diagram showing the magnetic disks 12 sorted into different cassette cases CS according to the flatness when manufacturing the magnetic disk drive 10 according to the embodiment. As shown in FIG. 5, the individual magnetic disks 12 are sorted into different cassette cases CS according to the flatness.

[0061] In the example of FIG. 5, the magnetic disk 12 with a flatness range of 0 μm or more and 10 μm or less is accommodated in the cassette case CS1, the magnetic disk 12 with a flatness range of 11 μm or more and 20 μm or less is accommodated in the cassette case CS2, the magnetic disk 12 with a flatness range of 21 μm or more and 30 μm or less is accommodated in the cassette case CS3, and the magnetic disk 12 with a flatness range of 31 μm or more and 40 μm or less is accommodated in the cassette case CS4.

[0062] These magnetic disks 12 are accommodated in the cassette cases CS1 to CS4 with the end displacement directions aligned. For example, a plurality of magnetic disks 12 corresponding to the number of a plurality of magnetic disk devices 10 are accommodated in one cassette case CS. Therefore, when manufacturing one magnetic disk device 10, the assembly is performed using some of the magnetic disks 12 in one cassette case CS.

[0063] In the manufacturing process of the magnetic disk device 10 according to the embodiment, shims 11s having different thicknesses are prepared and used for different flatness ranges.

[0064] FIG. 6 is a diagram showing an example of the types of shims 11s used in the manufacture of the magnetic disk device 10 according to the embodiment. As shown in FIG. 6, a plurality of types of shims 11s having thicknesses corresponding to these flatnesses are prepared according to the flatness range of the magnetic disk 12.

[0065] For the magnetic disk 12 accommodated in the cassette case CS1 and having a flatness range of 0 μm or more and 10 μm or less, for example, a shim 11s having a thickness SH1 of 0.10 mm is prepared. For the magnetic disk 12 accommodated in the cassette case CS2 and having a flatness range of 11 μm or more and 20 μm or less, for example, a shim 11s having a thickness SH2 of 0.11 mm is prepared. For the magnetic disk 12 accommodated in the cassette case CS3 and having a flatness range of 21 μm or more and 30 μm or less, for example, a shim 11s having a thickness SH3 of 0.12 mm is prepared. For the magnetic disk 12 accommodated in the cassette case CS4 and having a flatness range of 31 μm or more and 40 μm or less, for example, a shim 11s having a thickness SH4 of 0.13 mm is prepared.

[0066] FIGS. 7 and 8 are schematic views showing a process of assembling the magnetic disk 12 to the spindle 19 in the magnetic disk device 10 according to the embodiment.

[0067] As shown in FIG. 7(a), one of the cassette cases CS in which the magnetic disk 12 having a flatness within a predetermined range is accommodated is selected. On the other hand, on the spindle motor 11, the hub 191 of the spindle 19 is installed via a shim 11s having a thickness corresponding to the flatness of the magnetic disk 12 in the cassette case CS.

[0068] As shown in FIG. 7(b), the first magnetic disk 12 is taken out from the cassette case CS and set on the hub 191 into which the shim 11s is inserted at the lower end. At this time, the magnetic disk 12 is set so as to be in the face-down orientation.

[0069] As shown in FIG. 7(c), the spacer 192 is set on the first magnetic disk 12.

[0070] As shown in FIG. 7(d), the second magnetic disk 12 is taken out from the cassette case CS and set on the hub 191 on the first magnetic disk 12 via the spacer 192. Also at this time, the second magnetic disk 12 is set so as to be in the face-down orientation in accordance with the orientation of the first magnetic disk 12.

[0071] As shown in FIGS. 8(a) to 8(c), the process of setting the magnetic disk 12 to the hub 191 via the spacer 192 is continued until the last magnetic disk 12.

[0072] As shown in FIG. 8(d), when all the magnetic disks 12 are set to the hub 191, the upper end portion of the hub 191 is tightened by the clamp 193. Thereby, a plurality of magnetic disks 12 with flatness within a predetermined range are assembled to the spindle 19 in a state where the deviation directions are aligned. Note that by tightening the upper end portion of the hub 191 with the clamp 193, the warpage amount of at least the upper layer side magnetic disk 12 is slightly reduced.

[0073] Thus, the assembly process of the magnetic disk device 10 of the embodiment is completed.

[0074] (Comparative Example) Next, with reference to FIG. 9, the magnetic disk device of the comparative example will be described. In the magnetic disk device of the comparative example, a plurality of magnetic disks 12 are randomly assembled to the spindle 19 without considering the flatness size, deviation direction, etc. As a result, on one spindle 19, a substantially flat magnetic disk 12f, a magnetic disk 12c with an upside-down bowl shape, and an upward bowl-shaped magnetic disk 12r are mixed.

[0075] In this case, in the substantially flat magnetic disk 12f, the end portion is disposed at substantially the center in the vertical direction within the groove of the corresponding ramp 151x of the ramp load mechanism 15x, whereas the end portion of the magnetic disk 12c with an upside-down bowl shape is displaced downward within the groove of the ramp 151x, and the end portion of the bowl-shaped magnetic disk 12r is displaced upward within the groove of the ramp 151x.

[0076] As the magnetic disk 12 becomes thinner and multi-layered, the gap between the magnetic disk 12 and the upper and lower surfaces of the groove of the lamp 151x becomes narrower. Therefore, if the warpage amount of the thinned magnetic disk 12 increases, the contact risk between the magnetic disk 12 and the lamp 151x will increase. When an external impact is applied to the magnetic disk device, these contact risks will further increase, the operating shock resistance will decrease, and the reliability of the magnetic disk device will be impaired.

[0077] In addition, due to the warpage of the randomly arranged magnetic disks 12, there are portions where the gap between the magnetic disk 12 and the upper and lower surfaces of the groove of the lamp 151x becomes narrower and portions where it becomes wider, making it difficult to secure the design margin of the magnetic disk device.

[0078] According to the manufacturing method of the magnetic disk device 10 of the embodiment, the relative height between the spindle 19 and the plurality of lamps 151 is adjusted, and a plurality of magnetic disks 12 whose ends are displaced from the geometric plane with the center point as a reference are assembled in parallel along the axial direction of the spindle 19 with the displacement directions of the ends from the center point aligned.

[0079] In this way, since the magnetic disks 12 are assembled to the spindle 19 with the displacement directions of the ends from the center point aligned, the gaps between the individual magnetic disks 12 and the corresponding lamps 151 can be made substantially uniform. At this time, since the displacement directions of the ends from the center point are aligned, when the spindle 19 and the plurality of lamps 151 have an initial relative height, the gaps between the magnetic disks 12 and the lamps 151 will have the regularity that they all become narrower in the warpage direction of the magnetic disks 12.

[0080] Furthermore, even when a plurality of magnetic disks 12 with ends deviated from the geometric plane with respect to the center point are assembled by adjusting the relative height between the spindle 19 and the plurality of lamps 151, the gap between these magnetic disks 12 and the corresponding lamps 151 can be appropriately maintained. In this way, simply aligning the warping directions of the plurality of magnetic disks 12 is not sufficient to reduce the contact risk between the magnetic disks 12 and the lamps 151, and it is further necessary to adjust the relative height between the spindle 19 and the plurality of lamps 151.

[0081] Thereby, the design margin of the magnetic disk device 10 can be ensured, and the contact risk between the magnetic disk 12 and the lamp 151 can be reduced, improving the shock resistance of the operating magnetic disk device 10.

[0082] According to the manufacturing method of the magnetic disk device 10 of the embodiment, a plurality of magnetic disks 12c are selected so that the flatness is within a predetermined range, and a shim 11s having a predetermined thickness corresponding to the flatness of the magnetic disk 12c is installed near the lower end of the spindle 19 to adjust the relative height between the spindle 19 and the plurality of lamps 151, align the deviation directions of the ends so that the plurality of magnetic disks 12 are convex upward, and assemble the plurality of magnetic disks 12 to the spindle 19 on which the shim 11s is installed.

[0083] By selecting the individual magnetic disks 12 according to the flatness, it becomes easier to further ensure the design margin of the magnetic disk device 10.

[0084] Also, for example, when the initial relative height between the spindle 19 and the plurality of lamps 151 is optimized for a substantially flat magnetic disk 12, by assembling the magnetic disk 12 to the spindle 19 so as to be convex upward as described above, the end of the magnetic disk 12 will approach the lower surface side of the lamp 151. In this case, by installing the shim 11s near the lower end of the spindle 19, the gap between the magnetic disk 12 and the lamp 151 can be appropriately maintained.

[0085] Further, by assembling the magnetic disk 12 to the spindle 19 so as to be convex upward, there is also an advantage that the upward convex shape of the magnetic disk 12 is slightly corrected by the clamp 193.

[0086] According to the manufacturing method of the magnetic disk device 10 of the embodiment, a plurality of shims 11s having different thicknesses are prepared so that the relative heights of the spindle 19 and the plurality of ramps 151 can be adjusted for a plurality of magnetic disk groups having different flatness ranges. Thereby, the gap between the magnetic disk 12 and the ramp 151 can be kept more appropriate.

[0087] (Modification 1) Next, with reference to FIGS. 10 and 11, the magnetic disk device according to Modification 1 of the embodiment will be described. The magnetic disk device according to Modification 1 is different from the above-described embodiment in that the initial relative height between the spindle 19 and the plurality of ramps 151 is optimized for the magnetic disk 12 having a large amount of warpage.

[0088] In the following drawings, the same components as those in the configuration of the above-described embodiment may be denoted by the same reference numerals, and the description thereof may be omitted.

[0089] FIG. 10 is a schematic diagram showing an example in the case where the magnetic disk 12c having a flatness within a predetermined range is assembled in the magnetic disk device according to Modification 1 of the embodiment. FIG. 10(a) shows the entirety of the plurality of magnetic disks 12c assembled to the spindle 19. FIG. 10(b) shows an enlarged cross section of the ramp loading mechanism 15 provided near the end of the plurality of magnetic disks 12c.

[0090] In the example shown in FIG. 10, the initial relative height between the spindle 19 and the plurality of lamps 151 is optimized for the magnetic disk 12 having the maximum warpage amount that the magnetic disk 12 can have. In this case, when the magnetic disk 12c having a warpage amount smaller than the maximum warpage amount is assembled, at the initial relative height between the spindle 19 and the plurality of lamps 151, the end portion of the magnetic disk 12c will be disposed close to the upper surface within the groove of the corresponding lamp 151. The silhouette of the lamp 151 in FIG. 10(b) shows such a state of the magnetic disk 12r.

[0091] As shown in FIG. 10, in order to optimize the end position of the magnetic disk 12c arranged as described above, when assembling the magnetic disk 12c having a warpage amount smaller than the maximum warpage amount, a shim 15s having a thickness corresponding to the flatness of these magnetic disks 12c is inserted into the lower end portion of the lamp loading mechanism 15. Thereby, the entire lamp loading mechanism 15 including the plurality of lamps 151 will be lifted upward, and the end position of the magnetic disk 12c with respect to the corresponding lamp 151 can be optimized.

[0092] Here, the base member of the magnetic disk device in which the lamp loading mechanism 15 including the plurality of lamps 151 is installed is made of, for example, aluminum. Therefore, it is preferable that the shim 15s inserted between the lamp loading mechanism 15 and the base member of the magnetic disk device is also made of aluminum.

[0093] FIG. 11 is a diagram showing an example of the types of shims 15s used in the manufacture of the magnetic disk device according to Modification 1 of the embodiment. As shown in FIG. 11, also in the manufacturing process of the magnetic disk device of Modification 1, a plurality of types of shims 15s having thicknesses corresponding to these flatnesses are prepared according to the range of the flatness of the magnetic disk 12.

[0094] As in the example shown in FIG. 5 above, when distributing the individual magnetic disks 12, for a magnetic disk 12 with a flatness range of 0 μm or more and 10 μm or less, for example, a shim 15s with a thickness SH1 of 0.13 mm is prepared. For a magnetic disk 12 with a flatness range of 11 μm or more and 20 μm or less, for example, a shim 15s with a thickness SH2 of 0.12 mm is prepared. For a magnetic disk 12 with a flatness range of 21 μm or more and 30 μm or less, for example, a shim 15s with a thickness SH3 of 0.11 mm is prepared. For a magnetic disk 12 with a flatness range of 31 μm or more and 40 μm or less, for example, a shim 11s with a thickness SH4 of 0.10 mm is prepared.

[0095] Thus, also in the magnetic disk drive of Modification 1 including the spindle 19 and the plurality of ramps 151 in which the initial relative height is optimized for the magnetic disk 12 with the maximum warpage amount, by inserting a shim 15s with an appropriate thickness at the lower end of the ramp loading mechanism 15, the relative height between the spindle 19 and the plurality of ramps 151 can be optimized for each of the plurality of magnetic disks 12 with different flatness ranges.

[0096] According to the magnetic disk drive of Modification 1, the same effects as those of the magnetic disk drive 10 of the above-described embodiment are achieved.

[0097] (Modification 2) Next, with reference to FIGS. 12 and 13, the magnetic disk drive of Modification 2 of the embodiment will be described. In the magnetic disk drive of Modification 2, the point that the magnetic disk 12 is assembled to the spindle 19 so as to be an upward bowl shape is different from the above-described embodiment.

[0098] In the following drawings, the same components as those in the configuration of the above-described embodiment may be denoted by the same reference numerals, and the description thereof may be omitted.

[0099] FIG. 12 is a schematic diagram showing an example in the case where a magnetic disk 12r having flatness within a predetermined range is assembled in the magnetic disk device according to Modification 2 of the embodiment. FIG. 12(a) shows the whole of a plurality of magnetic disks 12r assembled to a spindle 19. FIG. 12(b) shows an enlarged cross section of a ramp load mechanism 15 provided near the end portion of the plurality of magnetic disks 12r.

[0100] In the example shown in FIG. 12, the initial relative height between the spindle 19 and the plurality of ramps 151 is optimized for, for example, a substantially flat magnetic disk 12. In this case, when the magnetic disk 12r having a predetermined flatness instead of being flat and having an upward bowl shape, that is, a downward convex shape, is assembled, at the initial relative height between the spindle 19 and the plurality of ramps 151, the end portion of the magnetic disk 12r will be disposed close to the upper surface within the groove of the corresponding ramp 151. The silhouette of the ramp 151 in FIG. 12(b) shows such a state of the magnetic disk 12r.

[0101] As shown in FIG. 12, even in such a case, in order to optimize the end positions of the upward bowl-shaped magnetic disks 12r, a shim 15s having a thickness corresponding to the flatness of those magnetic disks 12r is inserted into the lower end portion of the ramp load mechanism 15. Thereby, the whole of the ramp load mechanism 15 including the plurality of ramps 151 will be lifted upward, and the end position of the magnetic disk 12r with respect to the corresponding ramp 151 can be optimized.

[0102] Note that, as described above, when the magnetic disk 12r is assembled such that the displacement direction of the end portion from the center point is upward, among the housings of the magnetic disk device in which the top cover and the base member are combined, the end portion of the magnetic disk 12r is displaced toward the top cover side. Therefore, based on the magnetic disk device, the displacement direction of the end portion of the magnetic disk 12r as described above may be referred to as the top cover direction. That is, in the magnetic disk device shown in FIG. 12, the end portion of the magnetic disk 12c has a predetermined displacement amount (displacement quantity) in the top cover direction from the center point of the magnetic disk 12c.

[0103] FIG. 13 is a schematic diagram showing another example in the case where a magnetic disk 12r with flatness within a predetermined range is assembled in the magnetic disk device according to Modification Example 2 of the embodiment. FIG. 13(a) shows the whole of a plurality of magnetic disks 12r assembled to a spindle 19. FIG. 13(b) shows an enlarged cross section of a ramp load mechanism 15 provided near the end of the plurality of magnetic disks 12r.

[0104] In the example shown in FIG. 13, the initial relative height between the spindle 19 and the plurality of ramps 151 is optimized for the magnetic disk 12 having the maximum warpage amount that the magnetic disk 12 can have. In this case, when the magnetic disk 12r having a warpage amount smaller than the maximum warpage amount is assembled so as to be an upward bowl shape, at the initial relative height between the spindle 19 and the plurality of ramps 151, the end portion of the magnetic disk 12r will be disposed close to the lower surface in the groove of the corresponding ramp 151. The broken line in FIG. 13(b) shows such a state of the magnetic disk 12r.

[0105] As shown in FIG. 13, in order to optimize the end position of the magnetic disk 12r arranged as described above, when assembling the magnetic disk 12r having a warpage amount smaller than the maximum warpage amount, a shim 11s having a thickness corresponding to the flatness of those magnetic disks 12r is inserted into the lower end portion of the hub 191 of the spindle 19. Thereby, the whole of the spindle 19 with the plurality of magnetic disks 12r assembled thereto is lifted upward, and the end position of the magnetic disk 12r with respect to the corresponding ramp 151 can be optimized.

[0106] Although some embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalent scope thereof.

Description of Reference Numerals

[0107] 10... magnetic disk device, 11... spindle motor, 11s, 15s... shim, 12, 12c, 12f, 12r... magnetic disk, 13... magnetic head, 19... spindle, 191... hub, 192... spacer, 193... clamp.

Claims

1. Aligning the central axes of a plurality of magnetic disks whose ends are displaced from a geometric plane with respect to a center point and rotatable spindle, and adjusting the relative heights of a plurality of lamps respectively arranged at the end positions of the plurality of magnetic disks, Aligning the displacement directions of the ends from the center point and assembling the plurality of magnetic disks along the axial direction of the spindle, A method for manufacturing a magnetic disk device.

2. Selecting the plurality of magnetic disks so that the amount of displacement of the ends from the geometric plane with respect to the center point is within a predetermined range, Installing a shim having a predetermined thickness corresponding to the amount of displacement near the lower end of the spindle to adjust the relative height between the spindle and the plurality of lamps, Aligning the displacement directions of the ends so that the plurality of magnetic disks are convex upward, and assembling the plurality of magnetic disks to the spindle on which the shim is installed, The method for manufacturing a magnetic disk device according to claim 1.

3. Selecting the plurality of magnetic disks so that the amount of displacement of the ends from the geometric plane with respect to the center point is within a predetermined range, Installing a shim having a predetermined thickness corresponding to the amount of displacement near the lower end of a lamp loading mechanism including the plurality of lamps to adjust the relative height between the spindle and the plurality of lamps, Aligning the displacement directions of the ends so that the plurality of magnetic disks are convex downward, and assembling the plurality of magnetic disks to the spindle, The method for manufacturing a magnetic disk device according to claim 1.

4. Selecting the plurality of magnetic disks as a first magnetic disk group so that the amount of displacement of the ends from the geometric plane with respect to the center point is within a predetermined range, Selecting a second magnetic disk group whose amount of displacement is larger than that of the first magnetic disk group, Selecting a third magnetic disk group whose amount of displacement is smaller than that of the first magnetic disk group, Preparing a plurality of shims having different thicknesses so that the relative height between the spindle and the plurality of lamps can be adjusted respectively for the first to third magnetic disk groups, The method for manufacturing a magnetic disk device according to claim 1.

5. Selecting the plurality of magnetic disks as a first magnetic disk group so that the amount of displacement of the ends from the geometric plane with respect to the center point is within a predetermined range, Selecting a second magnetic disk group whose amount of displacement is larger than that of the first magnetic disk group, A shim having a predetermined thickness corresponding to the amount of displacement of the first magnetic disk group is installed near the lower end of the lamp load mechanism including the plurality of lamps to adjust the relative height between the spindle and the plurality of lamps. Align the displacement directions of the ends so that the first magnetic disk group is convex upward, and assemble the first magnetic disk group to the spindle. A method of manufacturing a magnetic disk device according to claim 1.

6. Select a plurality of magnetic disks as a first magnetic disk group so that the amount of displacement of the ends from the geometric plane based on the center point is within a predetermined range. Select a second magnetic disk group having a larger amount of displacement than the first magnetic disk group. A shim having a predetermined thickness corresponding to the amount of displacement of the first magnetic disk group is installed near the lower end of the spindle to adjust the relative height between the spindle and the plurality of lamps. Align the displacement directions of the ends so that the first magnetic disk group is convex downward, and assemble the first magnetic disk group to the spindle. A method of manufacturing a magnetic disk device according to claim 1.

7. A plurality of magnetic disks with ends displaced from a geometric plane with respect to a center point, A spindle rotatable with the central axes of the plurality of magnetic disks aligned, A lamp load mechanism including a plurality of lamps respectively arranged at the end positions of the plurality of magnetic disks, A shim having a predetermined thickness and capable of adjusting the relative height between the spindle and the plurality of lamps, and The plurality of magnetic disks are Assembled along the axial direction of the spindle in a state where the displacement directions of the ends from the center point are aligned. Magnetic disk device.

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