Signaling method and apparatus for write assist of high coercivity media using integrated half coil
View Patent ↗A signaling method and apparatus for providing two write assist components for perpendicular thin film heads writing to high coercivity media is disclosed. The two components provided by the present invention include a media writing assist component and a head switching assist component. Circuit wiring configurations and waveforms for driving an auxiliary half coil are disclosed. These include configurations for connecting the auxiliary half coil in parallel with the main data coil, or connecting the auxiliary half coil to the thermal flight control system. Provision for both common mode signals as well as differential mode signals are disclosed. RF sinusoidal waveforms between 1 and 5 GHz have been found suitable for head switching assist functions for either symmetric current feed and common mode current configuration, or asymmetric current feed and differential mode current configuration. RF sinusoidal waveforms between 10 and 50 GHz have been found suitable for media writing assist functions for either asymmetric or symmetric current feed and differential mode configuration. Data derived signals obtained by passing the data pulse train though high pass filtration has been found to provide both head switching assist and media writing assist functionality. Data derived signals can be used with or without the RF signals.
1. A method for writing data signals with a perpendicular head comprising:
providing a perpendicular head having a pole layer, said pole layer having a flare point, a main coil,
an auxiliary half coil, extending around three sides of said pole layer at an air bearing surface, said auxiliary half coil having a first terminating end and a second terminating end,
a first conductive element coupled to said first terminating end of said auxiliary half coil, said first conductive element extending from said air bearing surface, approximately perpendicular to said air bearing surface, to beyond said flare point of said pole layer, and a second conductive element coupled to said second terminating end of said auxiliary half coil, said second conductive element extending from said air bearing surface, approximately perpendicular to said air bearing surface, to beyond said flare point of said pole layer;
providing a data signal current to said main coil; and
providing a differential high frequency signal current, said differential high frequency signal current flowing through said first conductive element, through said second conductive element, and through said auxiliary half coil.
2. The method as recited in claim 1 , wherein said differential high frequency signal current is an RF sinusoidal waveform.
3. The method as recited in claim 2 , wherein said RF sinusoidal waveform has a frequency between 1 and 5 GHz.
4. The method as recited in claim 2 , wherein said RF sinusoidal waveform has a frequency between 10 and 50 GHz.
5. The method as recited in claim 2 , wherein said RF sinusoidal waveform has a frequency between 40 and 50 GHz.
6. The method as recited in claim 1 , wherein said differential high frequency signal current is derived from said data signal current.
7. The method as recited in claim 6 , wherein said differential high frequency signal current is obtained by passing a portion of said data signal current through a high pass filter.
8. The method as recited in claim 7 , wherein said high pass filter comprises a capacitor coupled to said auxiliary half coil.
9. The method as recited in claim 1 ,
wherein said first conductive element is displaced a first distance from said pole layer, said first distance being measured from said pole layer to said first conductive element at the air bearing surface;
wherein said second conductive element is displaced a second distance from said pole layer, said second distance being measured from said pole layer to said second conductive element at the air bearing surface; and
wherein said first distance is approximately equal to said second distance.
10. The method as recited in claim 9 , further comprising:
providing a first common mode high frequency signal current, said first common mode high frequency signal current flowing through said first conductive element; and
providing a second common mode high frequency signal current, said second common mode high frequency signal current flowing though said second conductive element,
wherein said first common mode high frequency signal current and said second common mode high frequency signal current have approximately equal magnitude, phase, and frequency.
11. The method as recited in claim 10 , wherein said first common mode high frequency signal current and said second common mode high frequency signal current are RF sinusoidal waveforms.
12. The method as recited in claim 11 , wherein said RF sinusoidal waveforms have a frequency between 1 and 5 GHz.
13. The method as recited in claim 10 , wherein said first common mode high frequency signal current and said second common mode high frequency signal current are derived from said data signal current.
14. The method as recited in claim 13 , wherein said first common mode high frequency signal current and said second common mode high frequency signal current are obtained by passing a portion of said data signal current through a high pass filter.
15. The method as recited in claim 14 , wherein said high pass filter comprises a first capacitor coupled to said first conductive element and a second capacitor coupled to said second conductive element.
16. The method as recited in claim 1 ,
wherein said first conductive element is displaced a first distance from said pole layer, said first distance being measured from said pole layer to said first conductive element at the air bearing surface;
wherein said second conductive element is displaced a second distance from said pole layer, said second distance being measured from said pole layer to said second conductive element at the air bearing surface; and
wherein said first distance is greater than said second distance.
17. The method as recited in claim 16 , wherein said differential high frequency signal current is an RF sinusoidal waveform.
18. The method as recited in claim 17 , wherein said RF sinusoidal waveform has a frequency between 10 and 50 GHz.
19. The method as recited in claim 17 , wherein said RF sinusoidal waveform has a frequency between 40 and 50 GHz.
20. The method as recited in claim 16 , wherein said differential high frequency signal current is derived from said data signal current.
21. The method as recited in claim 20 , wherein said differential high frequency signal current is obtained by passing a portion of said data signal current through a high pass filter.
22. The method as recited in claim 21 , wherein said high pass filter comprises a first capacitor coupled to said first conductive element and a second capacitor coupled to said second conductive element.