Patent Application
20080084637
Disclosed is a head that flies relative to a disk of a hard disk drive. The head includes a substrate that has a pole tip, and an air bearing surface that has at least one rail and a central pad. The air bearing surface also has a plurality of contact dots that each make contact with the disk at different skew angles. Providing contact at different skew angles insures that multiple dots do not make contact with the same track of the disk. This is particularly advantageous when the head is landed on the disk at the same skew angle.
Referring to the drawings more particularly by reference numbers,
Each head 20 may be gimbal mounted to a flexure 26 as part of a head gimbal assembly (HGA). The flexure 26 are attached to an actuator arm 28 that is pivotally mounted to the base plate 16 by a bearing assembly 30. A voice coil 32 is attached to the actuator arm 28. The voice coil 32 is coupled to a magnet assembly 34 to create a voice coil motor (VCM) 36. Providing a current to the voice coil 32 will create a torque that swings the actuator arm 28 and moves the heads 20 across the disks 12.
The hard disk drive 10 may include a printed circuit board assembly 38 that includes a plurality of integrated circuits 40 coupled to a printed circuit board 42. The printed circuit board 40 is coupled to the voice coil 32, heads 20 and spindle motor 14 by wires (not shown).
The air bearing surface 52 may include a plurality of contact dots 58, 60, 62, 64, 66 and 68. The dots 58, 60, 62, 64, 66 and 68 may have an outer layer of diamond (“DLC”) material that is relatively hard. The disk surfaces also typically have an outer layer of DLC. The similar DLC materials minimize scratching between the disk and heads.
The dots 58, 60, 62, 64, 66 and 68 are arranged so that different dots are aligned with the same skew angle but at different tracks of the disk when the head is parted on the landing zone of the disk. In this manner no more than one dot makes contact with any same track. This minimizes the damage to any single track during a head slapping event. Additionally, this approach also minimizes the amount of stiction wear during head take-off for any given track. During a stiction take-off period, the head makes contact with the disk primarily at the dot locations. If a dot is with the same disk wear track, the wear will be accelerated during the take-off period as well as touchdown period, increasing the amount of wear at the aligned track.
Each dot should preferably have a diameter no greater than 30 μm. The total surface area of the dots 58, 60, 62, 64, 66 and 68 is preferably less than 1 percent of the surface area of the air bearing surface 52. The above design situation will give the dot location flexibility to move around to avoid impacting the whole slider flying attitude.
The read/write channel circuit 162 is connected to the controller 166 through read and write channels 168 and 170, respectively, and read and write gates 172 and 174, respectively. The read gate 172 is enabled when data is to be read from the disks 12. The write gate 174 is to be enabled when writing data to the disks 12. The controller 166 may be a digital signal processor that operates in accordance with a software routine, including a routine(s) to write and read data from the disks 12. The read/write channel circuit 162 and controller 166 may also be connected to a motor control circuit 176 which controls a voice coil motor (not shown) and the spindle motor. The voice coil motor can move the heads 20 relative to the disks 12. The controller 166 may be connected to a non-volatile memory device 180. By way of example, the device 180 may be a read-only memory (“ROM”) that contains instructions that are read by the controller 166.
The circuit 150 may cause the heads 20 to move to a landing zone of the disk during a power down routine. The contact dots of the head are arranged so that no two dots are in contact with the same disk track while the head is landed or aligned with the pole-tip area. The circuit may also rotate the disks and cause the heads to take-off during a power up routine. The arrangement of contact dots minimizes the stiction wear on any given track between the head and disk during the power up routine.
While certain exemplary embodiments have been described and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative of and not restrictive on the broad invention, and that this invention not be limited to the specific constructions and arrangements shown and described, since various other modifications may occur to those ordinarily skilled in the art.
