Patent Application
20060103972
1. Field of the Invention
The present invention relates to a hard disk drive.
2. Background Information
Hard disk drives contain a plurality of magnetic heads that are coupled to rotating disks. The heads write and read information by magnetizing and sensing the magnetic fields of the disk surfaces. Each head is attached to a flexure arm to create a subassembly commonly referred to as a head gimbal assembly (“HGA”). The HGA's are suspended from an actuator arm. The actuator arm has a voice coil motor that can move the heads across the surfaces of the disks.
Information is typically stored on radial tracks that extend across the surface of each disk. Each track is typically divided into a number of segments or sectors. Each sector may include, among other things, a servo section and a data section. The servo sections are used to align the heads with the center of a track. The voice coil motor and actuator arm can move the heads to different tracks of the disks to access different data sectors. The voice coil motor is energized in accordance with signals from control circuits. The process of moving the heads from track to track is commonly referred to as a seek routine.
During the initial assembly of a disk drive the servo sections are written onto the disk(s). Servo is typically written onto the disk(s) by a servo writer. The servo writer writes servo in accordance with a predetermined track density. For example, the writer may write servo at 10,000 tracks per inch (“TPI”). The resultant disk will have servo sections at a density of 10,000 sections per inch measured across the radius of the disk(s).
It may be desirable to have a data track density that is different than the radial density of the servo sections. For example, because of head skew it may be desirable to have a data track density that is lower at the inner and outer diameter areas of the disk(s). It may be determined that the heads assembled in the disk optimally operate at track densities different from the track density of the servo sections. It would be desirable to have a disk drive that has a servo track density different from a data track density.
A hard disk drive having a disk that has a plurality of servo sections and a plurality of data sections. At least a portion of said data sections having a track density different than a track density of the servo sections.
Disclosed is a hard disk drive with a disk that has a plurality of servo sections and a plurality of data sections. At least some of the data sections have a track density different than the track density of the servo sections. The disk drive has a controller that may convert a data track number to a servo track number to compensate for the different densities. The conversion may be required to conduct a seek routine to access a data track associated with the data track number.
Referring to the drawings more particularly by reference numbers,
The disk drive 10 may include a plurality of heads 20 located adjacent to the disks 12. Each head 20 may have separate write (not shown) and read elements (not shown). The heads 20 are gimbal mounted to a flexure arm 26 as part of a head gimbal assembly (HGA). The flexure arms 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 read/write channel circuit 58 is connected to a controller 64 through read and write channels 66 and 68, respectively, and read and write gates 70 and 72, respectively. The read gate 70 is enabled when data is to be read from the disks 12. The write gate 72 is to be enabled when writing data to the disks 12. The controller 64 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 58 and controller 64 may also be connected to a motor control circuit 74 which controls the voice coil motor 36 and spindle motor 14 of the disk drive 10. The controller 64 may be connected to a non-volatile memory device 76. By way of example, the device 76 may be a read only memory (“ROM”).
As shown in
Each track is assigned a number that is used to access the track. The controller 64 determines which track should be accessed for reading and/or writing data. For example, the heads may be located at track number 2000. The controller 64 may determine that data is to be written at track 2050. The controller 64 provides a command(s) to excite the voice coil motor and move the heads to track 2050.
The servo sections 112 may have a track density along a radial direction of a disk surface. The data sections 114 may also have a track density measured along a radial direction. The track density of the data sections may be different from the track density of the servo sections 112. To account for the different densities the controller 64 converts the data track numbers to servo track numbers. The conversion may be performed in accordance with the following equation:
Y=f(x,h) (1)
Where;
y=the servo track number.
f=the conversion function.
x=the data track number.
h=the head track number.
By way of example, the disk may be segmented into three different regions, outer diameter (“OD”), middle diameter (“MD”) and inner diameter (“ID”). A servo writer may write the servo sections at a track density of 10,000 tracks per inch (“TPI”). The data sections in the OD region may have a track density of 5000 TPI. The MD region may have a data track density of 10,000 TPI, and the ID region may have a data track density of 7500 TPI. It may be desirable to have such variable track densities to compensate for different drive performances in the OD and ID of the disks. The conversion function may be the following piecewise linear function:
By way of example, with such a function the controller will convert data track number 2000 to servo track number 4000, or track number 4000 to 7000. The conversion function (2) is depicted graphically in
Due to the different characteristics of each head it may be desirable to vary the data track density per head. For example, assuming a 4 head drive and a servo track density of 10,000 TPI, the first head may have a data track density of 10,000, the second head a data track density of 9000 TPI, a third head with a data track density of 11,000 TPI and a fourth head having a data track density of 12,000 TPI. The conversion function may have the following form:
The function is graphically depicted in
Referring to
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.
