Disk drive releasing variable amount of buffered write data based on sliding window of predicted servo quality

Information

  • Patent Grant
  • 8922931
  • Patent Number
    8,922,931
  • Date Filed
    Wednesday, June 26, 2013
    11 years ago
  • Date Issued
    Tuesday, December 30, 2014
    10 years ago
Abstract
A disk drive is disclosed wherein N data wedges of write data are buffered in a buffer. After writing at least two of the data wedges to the disk including a first data wedge and a second data wedge, a first servo metric value is measured when reading a first servo sector, and a second servo metric value is predicted based on the first servo metric value, wherein the second servo metric value corresponds to a second servo sector following the first servo sector. When the first servo metric value indicates a safe write condition and the second servo metric value indicates an unsafe write condition, the first data wedge is released from the buffer, and when the first servo metric value indicates a safe write condition and the second servo metric value indicates a safe write condition, the first and second data wedges are released from the buffer.
Description
BACKGROUND

Disk drives comprise a disk and a head connected to a distal end of an actuator arm which is rotated about a pivot by a voice coil motor (VCM) to position the head radially over the disk. The disk comprises a plurality of radially spaced, concentric tracks for recording user data sectors and embedded servo sectors. The embedded servo sectors comprise head positioning information (e.g., a track address) which is read by the head and processed by a VCM servo controller to control the actuator arm as it seeks from track to track.



FIG. 1 shows a prior art disk format 2 as comprising a number of servo tracks 4 defined by servo sectors 60-6N recorded around the circumference of each servo track. Each servo sector 6, comprises a preamble 8 for storing a periodic pattern, which allows proper gain adjustment and timing synchronization of the read signal, and a sync mark 10 for storing a special pattern used to symbol synchronize to a servo data field 12. The servo data field 12 stores coarse head positioning information, such as a servo track address, used to position the head over a target data track during a seek operation. Each servo sector 6, further comprises groups of servo bursts 14 (e.g., N and Q servo bursts), which are recorded with a predetermined phase relative to one another and relative to the servo track centerlines. The phase based servo bursts 14 provide fine head position information used for centerline tracking while accessing a data track during write/read operations. A position error signal (PES) is generated by reading the servo bursts 14, wherein the PES represents a measured position of the head relative to a centerline of a target servo track. A servo controller processes the PES to generate a control signal applied to a head actuator (e.g., a voice coil motor) in order to actuate the head radially over the disk in a direction that reduces the PES.


An air bearing forms between the head and the disk due to the disk rotating at high speeds. Since the quality of the write/read signal depends on the fly height of the head, conventional heads (e.g., a magnetoresistive heads) may comprise an actuator for controlling the fly height. Any suitable fly height actuator may be employed, such as a heater which controls fly height through thermal expansion, or a piezoelectric (PZT) actuator. A dynamic fly height (DFH) servo controller may measure the fly height of the head and adjust the fly height actuator to maintain a target fly height during write/read operations.


Certain conditions may affect the ability of the VCM servo controller to maintain the head along the centerline of a target data track and/or the ability of the DFH servo controller to maintain the target fly height. For example, an external vibration applied to the disk drive or degradation and/or malfunction of the spindle motor that rotates the disks may induce a disturbance in the servo systems that cannot be adequately compensated. This is of particular concern during write operations when an off-track write may erase data in adjacent tracks, or an excessive fly height may render the written data unrecoverable due to under-saturation of the magnetic media. Accordingly, a disk drive will typically abort a write operation when the position error signal of the VCM servo controller or the fly height measurement of the DFH servo controller exceeds a write unsafe limit.





BRIEF DESCRIPTION OF THE DRAWINGS


FIG. 1 shows a prior art disk format comprising a plurality of servo tracks defined by servo sectors.



FIG. 2A shows a disk drive according to an embodiment comprising a head actuated over a disk.



FIG. 2B is a flow diagram according to an embodiment where data wedges that are buffered during a write operation are released based on a sliding window of predicted servo quality.



FIG. 2C illustrates an embodiment where a variable amount of data wedges are released during a write operation based on a servo metric measured for a current servo sector and a servo metric measured for a next servo sector.



FIG. 3 is a flow diagram according to an embodiment wherein one or two data wedges are released based on a servo metric measured for a current servo sector and a servo metric measured for a next servo sector.



FIGS. 4A-4C illustrate an embodiment where a write operation may be aborted, a single data wedge released, or two data wedges released based on a servo metric measured for a current servo sector and a servo metric measured for a next servo sector.



FIG. 5A illustrates an embodiment wherein two data wedges may be buffered during a write operation.



FIG. 5B illustrates an embodiment wherein more than three data wedges may be buffered during a write operation.



FIGS. 6A and 6B illustrate an embodiment where up to three data wedges may be released during a write operation based on a servo metric measured for a current servo sector and two future servo sectors.



FIGS. 7A-7D illustrate an embodiment wherein a single data wedge may be held in the buffer or released from the buffer based on a servo metric measured for a current and next servo sector.





DETAILED DESCRIPTION


FIG. 2A shows a disk drive comprising a disk 16 comprising a plurality of servo tracks 18 defined by servo sectors 200-20N, wherein data tracks are defined relative to the servo tracks 18 and the servo sectors 200-20N define data wedges in the data tracks (e.g., data wedge between servo sectors 202 and 203). The disk drive further comprises a head 22 actuated over the disk 16, and control circuitry 24 operable to execute the flow diagram of FIG. 2B, wherein write data is received from a host in connection with executing a write operation (block 26). N data wedges of the write data are buffered in a buffer (block 28), where N is greater than one. After writing at least two of the data wedges to the disk including a first data wedge and a second data wedge (block 30), a first servo metric value is measured when reading a first servo sector (block 32), and a second servo metric value is predicted based at least partly on the first servo metric value (block 34), wherein the second servo metric value corresponds to a second servo sector following the first servo sector. When the first servo metric value indicates a safe write condition and the second servo metric value indicates an unsafe write condition (block 36), the first data wedge is released from the buffer (block 38), and when the first servo metric value indicates a safe write condition and the second servo metric value indicates a safe write condition (block 40), the first and second data wedges are released from the buffer (block 42).



FIG. 2C shows an example buffer storing write data received from a host, wherein the control circuitry 24 maintains a number of data wedges of the write data in the buffer in the event that the current write operation is aborted due, for example, to an excessive PES or an excessive fly height. When a write operation is aborted while writing a current data wedge, it is assumed that a number of data wedges preceding the current data wedge may also be unreliable and should also be rewritten during a retry operation. If the write operation is not aborted when writing the current data wedge, a previously written data wedge is presumed reliable and therefore the corresponding memory segment in the buffer is released and the host notified that the corresponding data has been written to the disk. This delay in releasing the write data from the buffer and notifying the host of the completion of the write operation for the write data can reduce the performance of the disk drive as seen from the host when, for example, the delay results in slipped revolutions of the disk during sequential write operations.


Referring to the example of FIG. 2C, the delay in releasing data wedges from the buffer and notifying the host may be three data wedges long. After processing a current servo sector SS[0], the corresponding servo metric value is evaluated to determine whether to abort the write operation. If the servo metric value indicates a safe write condition, then the data wedge D_WEDGE[−2] written two wedges before the current data wedge D_WEDGE[0] is released from the buffer. When evaluating only the servo metric value of the current servo sector, the latency in releasing the data wedges remains fixed (e.g., at three data wedges in the example of FIG. 2C) which can degrade performance of the disk drive.


Accordingly, in one embodiment the latency in releasing the data wedges may be reduced based on a predicted servo metric value for one or more future servo sectors. This is illustrated in the example of FIG. 2C wherein a second servo metric value is predicted for the next servo sector SS[+1]. When the first and second servo metric values indicate a safe write condition, the control circuitry releases two data wedges from the buffer (D_WEDGE[−2] and D_WEDGE[−1]) thereby reducing the latency of releasing the data wedges by a full data wedge. When the first servo metric value indicates a safe write condition, but the second servo metric value indicates an unsafe write condition, then only data wedge D_WEDGE[−2] is released and the write operation continues. Accordingly, the latency of releasing data wedges may vary depending on the servo metric value predicted for the future servo sectors.


Any suitable technique may be employed to predict the servo metric value for a future servo sector. For example, in one embodiment the servo metric value for the next servo sector may be generated according to:

SM[k+1]=2·SM[k]−SM[k−1]

where SM[k+1] represents the servo metric value predicted for the next servo sector, SM[k] represents the servo metric value measured for the current servo sector, and SM[k−1] represents the servo metric value measured for the previous servo sector. In another embodiment, a state estimator may process the current and previously measured servo metric values in order to predict a servo metric value for a future servo sector.


In one embodiment, the tolerance for detecting a safe write condition based on the servo metric value predicted for a future servo sector may be tightened to help ensure the reliability of the written data before being released. This embodiment is understood with reference to the flow diagram of FIG. 3 which extends on the flow diagram of FIG. 2B, wherein the first servo metric value measured for the current servo sector is compared to a first threshold Th1 (block 40). If the first servo metric value exceeds the first threshold Th1 indicating an unsafe write condition, then the write operation is aborted and retried (block 42) as illustrated in FIG. 4A. When the first servo metric value does not exceed the first threshold indicating a safe write condition, then the data wedge D_WEDGE[−2] is released from the buffer (block 44). When the second servo metric value predicted for the next servo sector exceeds a second threshold Th2 lower than the first threshold Th1 indicating an unsafe write condition, the write operation is continued without releasing more data wedges (block 48) as illustrated in FIG. 4B. When the second metric value predicted for the next servo sector does not exceed the second, lower threshold Th2 indicating a safe write condition, an additional data wedge D_WEDGE[−1] is released (block 50) thereby reducing the latency as seen from the host as illustrated in FIG. 4C. Because the second threshold Th2 is lower than the first threshold Th1, the prediction of a safe write condition becomes more reliable so that the additional data wedge may be released with a higher degree of confidence.


Any suitable length latency window may be employed to delay the release of the data wedges from the buffer, wherein the longer the latency window, the higher the likelihood that the data was written reliably when released. FIG. 5A shows an embodiment wherein the latency window is reduced from three data wedges as shown in FIG. 2C to two data wedges, including the most recently written data wedge D_WEDGE[0] and the previously written data wedge D_WEDGE [−1]. This embodiment is essentially the same as shown in FIG. 2C except that the length of the latency window may vary between two and one data wedges depending on the servo metric value predicted for the next servo sector.



FIG. 5B shows an embodiment wherein the latency window is increased from three data wedges as shown in FIG. 2C to four data wedges. When the first servo metric value measured for the current servo sector indicates a safe write condition, the data wedge D_WEDGE[−3] is released, and when the second servo metric value predicted for the next servo sector indicates a safe write condition, the data wedge D_WEDGE[−2] is released. Accordingly, in this embodiment the length of the latency window may vary between four and three data wedges depending on the servo metric value predicted for the next servo sector.


A servo metric value may be predicted for more than just the next servo sector, and the additional servo metric values used to adjust the length of the latency window. FIG. 6A illustrates an embodiment wherein a servo metric value is predicted for the next two servo sectors SS[+1] and SS[+2]. In this embodiment, the length of the latency window may vary between four and two data wedges. For example, if the servo metric value for servo sectors SS[0], SS[+1], and SS[+2] all indicate a safe write condition, then the control circuitry may release three data wedges from the buffer which reduces the latency window to two data wedges as shown in FIG. 6A. If only the first two servo metric values for servo sectors SS[0] and SS[+1] indicate a safe write condition, then the control circuitry releases two data wedges from the buffer which reduces the latency window to three data wedges as shown in FIG. 6B. The embodiment shown in FIGS. 6A and 6B may employ a longer latency window, such as five data wedges, wherein the length of the latency window would vary between five and three data wedges. The embodiment shown in FIGS. 6A and 6B may be extended to evaluate the servo metric value predicted for additional future servo sectors so that the length of the latency window would vary over a greater number of data wedges.


The above described embodiments can also reduce the latency in releasing data wedges from the buffer by releasing a single data wedge (at the front of the latency window) when the servo metric value for both the current and next servo sector indicate a safe write condition. This embodiment is understood with reference to the flow diagram of FIG. 7A wherein when write data is received from the host in connection with executing a write operation (block 52), a first data wedge of the write data is buffered in a buffer (block 54). After writing the first data wedge to the disk (block 56), a first servo metric value is measured when reading a first servo sector (block 58), and a second servo metric value is predicted based at least partly on the first servo metric value (block 60), wherein the second servo metric value corresponds to a second servo sector following the first servo sector. When the first servo metric value indicates an unsafe write condition (block 62), the write operation is aborted (block 64) and retried as illustrated in FIG. 7B. When the first servo metric value indicates a safe write condition (block 62), and the second servo metric value indicates an unsafe write condition (block 66), the first data wedge is held in the buffer (block 68) and the write operation continues (block 70) as illustrated in FIG. 7C. When the first and second servo metric values indicate a safe write condition, the first data wedge is released from the buffer (block 72) as illustrated in FIG. 7D. Similar to the embodiment described above with reference to FIG. 6B, the flow diagram of FIG. 7A may be modified to hold or release a single data wedge based on a servo metric value predicted for more than a single servo sector following the current servo sector.


In one embodiment, the average length of the latency window while processing a write operation will be shorter as compared to the prior art technique that employs a fixed latency window. For example, varying the length of the latency window between three and two data wedges such that the average length of the latency window is, for example, 2.25 data wedges may provide an increase in performance from the host perspective as compared to employing a fixed length latency window of three data wedges.


Any suitable control circuitry may be employed to implement the flow diagrams in the above embodiments, such as any suitable integrated circuit or circuits. For example, the control circuitry may be implemented within a read channel integrated circuit, or in a component separate from the read channel, such as a disk controller, or certain operations described above may be performed by a read channel and others by a disk controller. In one embodiment, the read channel and disk controller are implemented as separate integrated circuits, and in an alternative embodiment they are fabricated into a single integrated circuit or system on a chip (SOC). In addition, the control circuitry may include a suitable preamp circuit implemented as a separate integrated circuit, integrated into the read channel or disk controller circuit, or integrated into a SOC.


In one embodiment, the control circuitry comprises a microprocessor executing instructions, the instructions being operable to cause the microprocessor to perform the flow diagrams described herein. The instructions may be stored in any computer-readable medium. In one embodiment, they may be stored on a non-volatile semiconductor memory external to the microprocessor, or integrated with the microprocessor in a SOC. In another embodiment, the instructions are stored on the disk and read into a volatile semiconductor memory when the disk drive is powered on. In yet another embodiment, the control circuitry comprises suitable logic circuitry, such as state machine circuitry.


The various features and processes described above may be used independently of one another, or may be combined in various ways. All possible combinations and subcombinations are intended to fall within the scope of this disclosure. In addition, certain method, event or process blocks may be omitted in some implementations. The methods and processes described herein are also not limited to any particular sequence, and the blocks or states relating thereto can be performed in other sequences that are appropriate. For example, described tasks or events may be performed in an order other than that specifically disclosed, or multiple may be combined in a single block or state. The example tasks or events may be performed in serial, in parallel, or in some other manner. Tasks or events may be added to or removed from the disclosed example embodiments. The example systems and components described herein may be configured differently than described. For example, elements may be added to, removed from, or rearranged compared to the disclosed example embodiments.


While certain example embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions disclosed herein. Thus, nothing in the foregoing description is intended to imply that any particular feature, characteristic, step, module, or block is necessary or indispensable. 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 inventions disclosed herein.

Claims
  • 1. A disk drive comprising: a disk comprising a plurality of servo tracks defined by servo sectors, wherein data tracks are defined relative to the servo tracks and the servo sectors define data wedges in the data tracks;a head actuated over the disk; andcontrol circuitry operable to: receive write data from a host in connection with executing a write operation;buffer N data wedges of the write data in a buffer, where N is greater than one;after writing at least two of the data wedges to the disk including a first data wedge and a second data wedge, measure a first servo metric value when reading a first servo sector;predict a second servo metric value based at least partly on the first servo metric value, wherein the second servo metric value corresponds to a second servo sector following the first servo sector;when the first servo metric value indicates a safe write condition and the second servo metric value indicates an unsafe write condition, release the first data wedge from the buffer; andwhen the first servo metric value indicates a safe write condition and the second servo metric value indicates a safe write condition, release the first and second data wedges from the buffer.
  • 2. The disk drive as recited in claim 1, wherein the second data wedge is written to the disk after the first data wedge.
  • 3. The disk drive as recited in claim 1, wherein when the first servo metric value indicates an unsafe write condition the control circuitry is operable to retry the write operation.
  • 4. The disk drive as recited in claim 1, wherein the servo metric comprises a position error signal (PES) representing a difference between a measured position of the head and a target position.
  • 5. The disk drive as recited in claim 1, wherein the servo metric comprises a fly height error representing a difference between a measured fly height of the head and a target fly height.
  • 6. The disk drive as recited in claim 1, wherein: the first servo metric value indicates a safe write condition when the first servo metric value is less than a first threshold; andthe second servo metric value indicates a safe write condition when the second servo metric value is less than a second threshold, where the second threshold is less than the first threshold.
  • 7. The disk drive as recited in claim 1, wherein N is greater than three and the control circuitry is further operable to: predict a third servo metric value based on the first servo metric value and the second servo metric value, wherein the third servo metric value corresponds to a third servo sector following the first servo sector;when the first servo metric value indicates a safe write condition and the second servo metric value indicates a safe write condition and the third servo metric value indicates an unsafe write condition, release the first and second data wedges from the buffer; andwhen the first servo metric value indicates a safe write condition and the second servo metric value indicates a safe write condition and the third servo metric value indicates a safe write condition, release the first, second and third data wedges from the buffer.
  • 8. A method of operating a disk drive comprising a head actuated over a disk comprising a plurality of servo tracks defined by servo sectors, wherein data tracks are defined relative to the servo tracks and the servo sectors define data wedges in the data tracks, the method comprising: receiving write data from a host in connection with executing a write operation;buffering N data wedges of the write data in a buffer, where N is greater than one;after writing at least two of the data wedges to the disk including a first data wedge and a second data wedge, measuring a first servo metric value when reading a first servo sector;predicting a second servo metric value based at least partly on the first servo metric value, wherein the second servo metric value corresponds to a second servo sector following the first servo sector;when the first servo metric value indicates a safe write condition and the second servo metric value indicates an unsafe write condition, releasing the first data wedge from the buffer; andwhen the first servo metric value indicates a safe write condition and the second servo metric value indicates a safe write condition, releasing the first and second data wedges from the buffer.
  • 9. The method as recited in claim 8, wherein the second data wedge is written to the disk after the first data wedge.
  • 10. The method as recited in claim 8, wherein when the first servo metric value indicates an unsafe write condition the method further comprises retrying the write operation.
  • 11. The method as recited in claim 8, wherein the servo metric comprises a position error signal (PES) representing a difference between a measured position of the head and a target position.
  • 12. The method as recited in claim 8, wherein the servo metric comprises a fly height error representing a difference between a measured fly height of the head and a target fly height.
  • 13. The method as recited in claim 8, wherein: the first servo metric value indicates a safe write condition when the first servo metric value is less than a first threshold; andthe second servo metric value indicates a safe write condition when the second servo metric value is less than a second threshold, where the second threshold is less than the first threshold.
  • 14. The method as recited in claim 8, wherein N is greater than three and the method further comprises: predicting a third servo metric value based on the first servo metric value and the second servo metric value, wherein the third servo metric value corresponds to a third servo sector following the first servo sector;when the first servo metric value indicates a safe write condition and the second servo metric value indicates a safe write condition and the third servo metric value indicates an unsafe write condition, releasing the first and second data wedges from the buffer; andwhen the first servo metric value indicates a safe write condition and the second servo metric value indicates a safe write condition and the third servo metric value indicates a safe write condition, releasing the first, second and third data wedges from the buffer.
  • 15. A disk drive comprising: a disk comprising a plurality of servo tracks defined by servo sectors, wherein data tracks are defined relative to the servo tracks and the servo sectors define data wedges in the data tracks;a head actuated over the disk; andcontrol circuitry operable to: receive write data from a host in connection with executing a write operation;buffer a first data wedge of the write data in a buffer;after writing the first data wedge to the disk, measure a first servo metric value when reading a first servo sector;predict a second servo metric value based at least partly on the first servo metric value, wherein the second servo metric value corresponds to a second servo sector following the first servo sector;when the first servo metric value indicates a safe write condition and the second servo metric value indicates an unsafe write condition, hold the first data wedge in the buffer; andwhen the first servo metric value indicates a safe write condition and the second servo metric value indicates a safe write condition, release the first data wedge from the buffer,wherein the first servo metric value indicates a safe write condition when the first servo metric value is less than a first threshold; andthe second servo metric value indicates a safe write condition when the second servo metric value is less than a second threshold, where the second threshold is less than the first threshold.
  • 16. The disk drive as recited in claim 15, wherein when the first servo metric value indicates an unsafe write condition the control circuitry is operable to retry the write operation.
  • 17. The disk drive as recited in claim 15, wherein the servo metric comprises a position error signal (PES) representing a difference between a measured position of the head and a target position.
  • 18. The disk drive as recited in claim 15, wherein the servo metric comprises a fly height error representing a difference between a measured fly height of the head and a target fly height.
  • 19. The disk drive as recited in claim 15, wherein the control circuitry is further operable to: predict a third servo metric value based on the first servo metric value and the second servo metric value, wherein the third servo metric value corresponds to a third servo sector following the first servo sector;when the first servo metric value indicates a safe write condition and the second servo metric value indicates a safe write condition and the third servo metric value indicates an unsafe write condition, hold the first data wedge in the buffer; andwhen the first servo metric value indicates a safe write condition and the second servo metric value indicates a safe write condition and the third servo metric value indicates a safe write condition, release the first data wedge from the buffer.
  • 20. A method of operating a disk drive comprising a head actuated over a disk comprising a plurality of servo tracks defined by servo sectors, wherein data tracks are defined relative to the servo tracks and the servo sectors define data wedges in the data tracks, the method comprising: receiving write data from a host in connection with executing a write operation;buffering a first data wedge of the write data in a buffer;after writing the first data wedge to the disk, measuring a first servo metric value when reading a first servo sector;predicting a second servo metric value based at least partly on the first servo metric value, wherein the second servo metric value corresponds to a second servo sector following the first servo sector;when the first servo metric value indicates a safe write condition and the second servo metric value indicates an unsafe write condition, holding the first data wedge in the buffer; andwhen the first servo metric value indicates a safe write condition and the second servo metric value indicates a safe write condition, releasing the first data wedge from the buffer,wherein the first servo metric value indicates a safe write condition when the first servo metric value is less than a first threshold; andthe second servo metric value indicates a safe write condition when the second servo metric value is less than a second threshold, where the second threshold is less than the first threshold.
  • 21. The method as recited in claim 20, wherein when the first servo metric value indicates an unsafe write condition the method further comprises retrying the write operation.
  • 22. The method as recited in claim 20, wherein the servo metric comprises a position error signal (PES) representing a difference between a measured position of the head and a target position.
  • 23. The method as recited in claim 20, wherein the servo metric comprises a fly height error representing a difference between a measured fly height of the head and a target fly height.
  • 24. The method as recited in claim 20, further comprising: predicting a third servo metric value based on the first servo metric value and the second servo metric value, wherein the third servo metric value corresponds to a third servo sector following the first servo sector;when the first servo metric value indicates a safe write condition and the second servo metric value indicates a safe write condition and the third servo metric value indicates an unsafe write condition, holding the first data wedge in the buffer; andwhen the first servo metric value indicates a safe write condition and the second servo metric value indicates a safe write condition and the third servo metric value indicates a safe write condition, releasing the first data wedge from the buffer.
CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to provisional U.S. Patent Application Ser. No. 61/822,485, filed on May 13, 2013, which is hereby incorporated by reference in its entirety.

US Referenced Citations (314)
Number Name Date Kind
5126895 Yasuda et al. Jun 1992 A
5392290 Brown et al. Feb 1995 A
5570244 Wiselogel Oct 1996 A
5831781 Okamura Nov 1998 A
5909334 Barr et al. Jun 1999 A
6014283 Codilian et al. Jan 2000 A
6052076 Patton, III et al. Apr 2000 A
6052250 Golowka et al. Apr 2000 A
6067206 Hull et al. May 2000 A
6078453 Dziallo et al. Jun 2000 A
6091564 Codilian et al. Jul 2000 A
6094020 Goretzki et al. Jul 2000 A
6101065 Alfred et al. Aug 2000 A
6104153 Codilian et al. Aug 2000 A
6122133 Nazarian et al. Sep 2000 A
6122135 Stich Sep 2000 A
6134610 Chung Oct 2000 A
6141175 Nazarian et al. Oct 2000 A
6160368 Plutowski Dec 2000 A
6181502 Hussein et al. Jan 2001 B1
6195222 Heminger et al. Feb 2001 B1
6198584 Codilian et al. Mar 2001 B1
6198590 Codilian et al. Mar 2001 B1
6204988 Codilian et al. Mar 2001 B1
6243223 Elliott et al. Jun 2001 B1
6281652 Ryan et al. Aug 2001 B1
6285521 Hussein Sep 2001 B1
6292320 Mason et al. Sep 2001 B1
6310742 Nazarian et al. Oct 2001 B1
6320718 Bouwkamp et al. Nov 2001 B1
6342984 Hussein et al. Jan 2002 B1
6347018 Kadlec et al. Feb 2002 B1
6369972 Codilian et al. Apr 2002 B1
6369974 Asgari et al. Apr 2002 B1
6429990 Serrano et al. Aug 2002 B2
6462896 Codilian et al. Oct 2002 B1
6476996 Ryan Nov 2002 B1
6484577 Bennett Nov 2002 B1
6493169 Ferris et al. Dec 2002 B1
6496315 Ueda et al. Dec 2002 B1
6496324 Golowka et al. Dec 2002 B1
6498698 Golowka et al. Dec 2002 B1
6507450 Elliott Jan 2003 B1
6534936 Messenger et al. Mar 2003 B2
6538839 Ryan Mar 2003 B1
6545835 Codilian et al. Apr 2003 B1
6549359 Bennett et al. Apr 2003 B1
6549361 Bennett et al. Apr 2003 B1
6560056 Ryan May 2003 B1
6568268 Bennett May 2003 B1
6574062 Bennett et al. Jun 2003 B1
6577465 Bennett et al. Jun 2003 B1
6614615 Ju et al. Sep 2003 B1
6614618 Sheh et al. Sep 2003 B1
6621652 Haines et al. Sep 2003 B2
6636377 Yu et al. Oct 2003 B1
6690536 Ryan Feb 2004 B1
6693764 Sheh et al. Feb 2004 B1
6707635 Codilian et al. Mar 2004 B1
6710953 Vallis et al. Mar 2004 B1
6710966 Codilian et al. Mar 2004 B1
6714371 Codilian Mar 2004 B1
6714372 Codilian et al. Mar 2004 B1
6724564 Codilian et al. Apr 2004 B1
6731450 Codilian et al. May 2004 B1
6735041 Codilian et al. May 2004 B1
6738220 Codilian May 2004 B1
6747837 Bennett Jun 2004 B1
6760186 Codilian et al. Jul 2004 B1
6788483 Ferris et al. Sep 2004 B1
6791785 Messenger et al. Sep 2004 B1
6795268 Ryan Sep 2004 B1
6819518 Melkote et al. Nov 2004 B1
6826006 Melkote et al. Nov 2004 B1
6826007 Patton, III Nov 2004 B1
6847502 Codilian Jan 2005 B1
6850383 Bennett Feb 2005 B1
6850384 Bennett Feb 2005 B1
6867944 Ryan Mar 2005 B1
6876508 Patton, III et al. Apr 2005 B1
6882496 Codilian et al. Apr 2005 B1
6885514 Codilian et al. Apr 2005 B1
6900958 Yi et al. May 2005 B1
6900959 Gardner et al. May 2005 B1
6903897 Wang et al. Jun 2005 B1
6914740 Tu et al. Jul 2005 B1
6914743 Narayana et al. Jul 2005 B1
6920004 Codilian et al. Jul 2005 B1
6924959 Melkote et al. Aug 2005 B1
6924960 Melkote et al. Aug 2005 B1
6924961 Melkote et al. Aug 2005 B1
6934114 Codilian et al. Aug 2005 B1
6934135 Ryan Aug 2005 B1
6937420 McNab et al. Aug 2005 B1
6937423 Ngo et al. Aug 2005 B1
6952322 Codilian et al. Oct 2005 B1
6954324 Tu et al. Oct 2005 B1
6958881 Codilian et al. Oct 2005 B1
6963465 Melkote et al. Nov 2005 B1
6965488 Bennett Nov 2005 B1
6967458 Bennett et al. Nov 2005 B1
6967811 Codilian et al. Nov 2005 B1
6970319 Bennett et al. Nov 2005 B1
6972539 Codilian et al. Dec 2005 B1
6972540 Wang et al. Dec 2005 B1
6972922 Subrahmanyam et al. Dec 2005 B1
6975480 Codilian et al. Dec 2005 B1
6977789 Cloke Dec 2005 B1
6980389 Kupferman Dec 2005 B1
6987636 Chue et al. Jan 2006 B1
6987639 Yu Jan 2006 B1
6989954 Lee et al. Jan 2006 B1
6992848 Agarwal et al. Jan 2006 B1
6992851 Cloke Jan 2006 B1
6992852 Ying et al. Jan 2006 B1
6995941 Miyamura et al. Feb 2006 B1
6999263 Melkote et al. Feb 2006 B1
6999267 Melkote et al. Feb 2006 B1
7006320 Bennett et al. Feb 2006 B1
7016134 Agarwal et al. Mar 2006 B1
7023637 Kupferman Apr 2006 B1
7023640 Codilian et al. Apr 2006 B1
7027256 Subrahmanyam et al. Apr 2006 B1
7027257 Kupferman Apr 2006 B1
7035026 Codilian et al. Apr 2006 B2
7046472 Melkote et al. May 2006 B1
7050249 Chue et al. May 2006 B1
7050254 Yu et al. May 2006 B1
7050258 Codilian May 2006 B1
7054098 Yu et al. May 2006 B1
7061714 Yu Jun 2006 B1
7064918 Codilian et al. Jun 2006 B1
7068451 Wang et al. Jun 2006 B1
7068459 Cloke et al. Jun 2006 B1
7068461 Chue et al. Jun 2006 B1
7068463 Ji et al. Jun 2006 B1
7088547 Wang et al. Aug 2006 B1
7095579 Ryan et al. Aug 2006 B1
7110208 Miyamura et al. Sep 2006 B1
7110214 Tu et al. Sep 2006 B1
7113362 Lee et al. Sep 2006 B1
7113365 Ryan et al. Sep 2006 B1
7116505 Kupferman Oct 2006 B1
7126781 Bennett Oct 2006 B1
7158329 Ryan Jan 2007 B1
7180703 Subrahmanyam et al. Feb 2007 B1
7184230 Chue et al. Feb 2007 B1
7196864 Yi et al. Mar 2007 B1
7199966 Tu et al. Apr 2007 B1
7203021 Ryan et al. Apr 2007 B1
7209321 Bennett Apr 2007 B1
7212364 Lee May 2007 B1
7212374 Wang et al May 2007 B1
7215504 Bennett May 2007 B1
7224543 Abrishamchian et al. May 2007 B1
7224546 Orakcilar et al. May 2007 B1
7245447 Zaitsu Jul 2007 B2
7248426 Weerasooriya et al. Jul 2007 B1
7251098 Wang et al. Jul 2007 B1
7253582 Ding et al. Aug 2007 B1
7253989 Lau et al. Aug 2007 B1
7265933 Phan et al. Sep 2007 B1
7289288 Tu Oct 2007 B1
7298574 Melkote et al. Nov 2007 B1
7301717 Lee et al. Nov 2007 B1
7304819 Melkote et al. Dec 2007 B1
7330019 Bennett Feb 2008 B1
7330327 Chue et al. Feb 2008 B1
7333280 Lifchits et al. Feb 2008 B1
7333290 Kupferman Feb 2008 B1
7339761 Tu et al. Mar 2008 B1
7365932 Bennett Apr 2008 B1
7388728 Chen et al. Jun 2008 B1
7391583 Sheh et al. Jun 2008 B1
7391584 Sheh et al. Jun 2008 B1
7433143 Ying et al. Oct 2008 B1
7440210 Lee Oct 2008 B1
7440225 Chen et al. Oct 2008 B1
7450334 Wang et al. Nov 2008 B1
7450336 Wang et al. Nov 2008 B1
7453661 Jang et al. Nov 2008 B1
7457071 Sheh Nov 2008 B1
7466509 Chen et al. Dec 2008 B1
7468855 Weerasooriya et al. Dec 2008 B1
7477471 Nemshick et al. Jan 2009 B1
7480116 Bennett Jan 2009 B1
7489464 McNab et al. Feb 2009 B1
7492546 Miyamura Feb 2009 B1
7495857 Bennett Feb 2009 B1
7499236 Lee et al. Mar 2009 B1
7502192 Wang et al. Mar 2009 B1
7502195 Wu et al. Mar 2009 B1
7502197 Chue Mar 2009 B1
7505223 McCornack Mar 2009 B1
7508616 Fitzpatrick et al. Mar 2009 B2
7542225 Ding et al. Jun 2009 B1
7545593 Sun et al. Jun 2009 B1
7548392 Desai et al. Jun 2009 B1
7551390 Wang et al. Jun 2009 B1
7558016 Le et al. Jul 2009 B1
7573670 Ryan et al. Aug 2009 B1
7576941 Chen et al. Aug 2009 B1
7580212 Li et al. Aug 2009 B1
7583470 Chen et al. Sep 2009 B1
7595954 Chen et al. Sep 2009 B1
7602575 Lifchits et al. Oct 2009 B1
7616399 Chen et al. Nov 2009 B1
7619844 Bennett Nov 2009 B1
7626782 Yu et al. Dec 2009 B1
7630162 Zhao et al. Dec 2009 B2
7639447 Yu et al. Dec 2009 B1
7656604 Liang et al. Feb 2010 B1
7656607 Bennett Feb 2010 B1
7660067 Ji et al. Feb 2010 B1
7663835 Yu et al. Feb 2010 B1
7675707 Liu et al. Mar 2010 B1
7679854 Narayana et al. Mar 2010 B1
7688534 McCornack Mar 2010 B1
7688538 Chen et al. Mar 2010 B1
7688539 Bryant et al. Mar 2010 B1
7697233 Bennett et al. Apr 2010 B1
7701661 Bennett Apr 2010 B1
7710676 Chue May 2010 B1
7715138 Kupferman May 2010 B1
7729079 Huber Jun 2010 B1
7733189 Bennett Jun 2010 B1
7746592 Liang et al. Jun 2010 B1
7746594 Guo et al. Jun 2010 B1
7746595 Guo et al. Jun 2010 B1
7760461 Bennett Jul 2010 B1
7800853 Guo et al. Sep 2010 B1
7800856 Bennett et al. Sep 2010 B1
7800857 Calaway et al. Sep 2010 B1
7839591 Weerasooriya et al. Nov 2010 B1
7839595 Chue et al. Nov 2010 B1
7839600 Babinski et al. Nov 2010 B1
7843662 Weerasooriya et al. Nov 2010 B1
7852588 Ferris et al. Dec 2010 B1
7852592 Liang et al. Dec 2010 B1
7859784 Ogawa Dec 2010 B2
7864481 Kon et al. Jan 2011 B1
7864482 Babinski et al. Jan 2011 B1
7869155 Wong Jan 2011 B1
7876522 Calaway et al. Jan 2011 B1
7876523 Panyavoravaj et al. Jan 2011 B1
7916415 Chue Mar 2011 B1
7916416 Guo et al. Mar 2011 B1
7916420 McFadyen et al. Mar 2011 B1
7916421 Liikanen et al. Mar 2011 B1
7916422 Guo et al. Mar 2011 B1
7929238 Vasquez Apr 2011 B1
7961422 Chen et al. Jun 2011 B1
8000053 Anderson Aug 2011 B1
8031423 Tsai et al. Oct 2011 B1
8054022 Ryan et al. Nov 2011 B1
8059357 Knigge et al. Nov 2011 B1
8059360 Melkote et al. Nov 2011 B1
8072703 Calaway et al. Dec 2011 B1
8077428 Chen et al. Dec 2011 B1
8078901 Meyer et al. Dec 2011 B1
8081395 Ferris Dec 2011 B1
8085020 Bennett Dec 2011 B1
8116023 Kupferman Feb 2012 B1
8145934 Ferris et al. Mar 2012 B1
8179626 Ryan et al. May 2012 B1
8189286 Chen et al. May 2012 B1
8213106 Guo et al. Jul 2012 B1
8254222 Tang Aug 2012 B1
8300348 Liu et al. Oct 2012 B1
8315005 Zou et al. Nov 2012 B1
8315006 Chahwan et al. Nov 2012 B1
8320069 Knigge et al. Nov 2012 B1
8351174 Gardner et al. Jan 2013 B1
8358114 Ferris et al. Jan 2013 B1
8358145 Ferris et al. Jan 2013 B1
8390367 Bennett Mar 2013 B1
8432031 Agness et al. Apr 2013 B1
8432629 Rigney et al. Apr 2013 B1
8451697 Rigney et al. May 2013 B1
8482873 Chue et al. Jul 2013 B1
8498076 Sheh et al. Jul 2013 B1
8498172 Patton, III et al. Jul 2013 B1
8508881 Babinski et al. Aug 2013 B1
8531798 Xi et al. Sep 2013 B1
8537486 Liang et al. Sep 2013 B2
8542455 Huang et al. Sep 2013 B2
8553351 Narayana et al. Oct 2013 B1
8564899 Lou et al. Oct 2013 B2
8576506 Wang et al. Nov 2013 B1
8605382 Mallary et al. Dec 2013 B1
8605384 Liu et al. Dec 2013 B1
8610391 Yang et al. Dec 2013 B1
8611040 Xi et al. Dec 2013 B1
8619385 Guo et al. Dec 2013 B1
8630054 Bennett et al. Jan 2014 B2
8630059 Chen et al. Jan 2014 B1
8634154 Rigney et al. Jan 2014 B1
8634283 Rigney et al. Jan 2014 B1
8643976 Wang et al. Feb 2014 B1
8649121 Smith et al. Feb 2014 B1
8654466 McFadyen Feb 2014 B1
8654467 Wong et al. Feb 2014 B1
8665546 Zhao et al. Mar 2014 B1
8665551 Rigney et al. Mar 2014 B1
8670206 Liang et al. Mar 2014 B1
8687312 Liang Apr 2014 B1
8693123 Guo et al. Apr 2014 B1
8693134 Xi et al. Apr 2014 B1
20060215307 Yoshida et al. Sep 2006 A1
20090290252 Fukase Nov 2009 A1
20100035085 Jung et al. Feb 2010 A1
20120284493 Lou et al. Nov 2012 A1
20130120870 Zhou et al. May 2013 A1
20130148240 Ferris et al. Jun 2013 A1
Provisional Applications (1)
Number Date Country
61822485 May 2013 US