Fly-height control and touchdown detection
An embedded contact sensor (ECS) element for fly-height control and touchdown detection. An embedded contact sensor (ECS) element with a resistance that changes with a temperature change, which senses a clearance change between a head slider and a disk of a disk drive. A resistance measurement section, within said head IC, that determines a value of direct current resistance (DCR) of said ECS element, wherein said value of DCR changes with a temperature change, wherein said temperature change is caused by an air bearing cooling and frictional induced heating at a head disk interface. A resistance slope to fly-height conversion section that dynamically determines a target fly-height value for said head slider over said disk based on changes in said value of DCR.
1. An embedded contact sensor (ECS) element, comprising:
said ECS element with a resistance that changes with a temperature change, that senses a clearance change between a head slider and a disk of a disk drive;
a resistance measurement section, within said head IC, that determines a value of direct current resistance (DCR) of said ECS element, wherein said value of DCR changes with said temperature change, wherein said temperature change is caused by an air bearing cooling and frictional induced heating at a head disk interface; and
a resistance slope to fly-height conversion section that dynamically determines a target fly-height value for said head slider over said disk based on changes in said value of DCR.
2. A disk drive comprising:
an embedded contact sensor (ECS) element with a resistance that changes with a temperature change, that senses a clearance change between a head slider and a disk;
a head integrated circuit (IC) comprising an amplification circuit section that amplifies a signal of said head slider;
a resistance measurement section, within said head IC, that determines a value of direct current resistance (DCR) of said ECS element, wherein said value of DCR changes with a temperature change, wherein said temperature change is caused by an air bearing cooling and frictional induced heating at a head disk interface;
a controller IC comprising a controller that accesses a register of said head IC for controlling said head IC; and
a resistance slope to fly-height conversion section that dynamically determines a target fly-height value for said head slider over said disk based on changes in said value of DCR.
3. The disk drive of claim 2 , further comprising:
a flying height adjusting section that measures a difference between a target fly-height and a current fly-height, and sends a report to a TFC power control to change a TFC heater power to adjust said current fly-height to reach said target fly-height value.
4. The disk drive of claim 2 , further comprising:
a fly-height monitoring section that reports and records a fly-height in real time.
5. The disk drive of claim 2 , wherein said value of DCR changes with a disturbance at said head disk interface wherein said disturbance is selected from the group of disturbances consisting of: disk surface variations, disk waviness, micro-waviness, lube buildup, lubricant moguls, and lube pickup.
6. The disk drive of claim 2 , wherein said ECS element is applied by a constant direct current in current mode.
7. The disk drive of claim 2 , wherein said ECS element is applied by a constant direct voltage in voltage mode.
8. The disk drive of claim 2 , wherein said resistance measurement section is timely recording a resistance value of said ECS element sensing a clearance change between said head slider and said disk at said head disk interface.
9. The disk drive of claim 2 , wherein said resistance slope to fly-height conversion section is dynamically recording fly-height by generating a resistance slope according to values of ECS resistance and thermal fly-height control (TFC) heater power reported by said head IC.
10. The disk drive of claim 9 , wherein a relationship between a DCR slope and fly-height is determined and stored in said controller IC.
11. The disk drive of claim 2 , further comprising:
a plurality of head sliders, wherein an identification section is common to said plurality of said head sliders.
12. The disk drive of claim 2 , wherein a TFC power is reduced for a touchdown detection.
13. The disk drive of claim 2 , further comprising:
a touchdown detection section to compare a measured fly-height value with a prescribed threshold value, and a fault signal for signaling an occurrence of a touchdown between said head slider and said disk.
14. A disk drive comprising:
an embedded contact sensor (ECS) element with a resistance that changes with a temperature change, that senses a clearance change between a head slider and a disk;
a head integrated circuit (IC) comprising an amplification circuit section that amplifies a signal of said head slider;
a resistance measurement section, within said head IC, that determines a value of direct current resistance (DCR) of said ECS element, wherein said value of DCR changes with said temperature change, wherein said temperature change is caused by an air bearing cooling and frictional induced heating at a head disk interface;
a controller IC comprising a controller that accesses a register of said head IC for controlling said head IC;
a resistance slope to fly-height conversion section that dynamically determines a target fly-height value for said head slider over said disk based on changes in said value of DCR; and
a flying height adjusting section that measures a difference between a target fly-height and a current fly-height, and sends a report to a TFC power control to change a TFC heater power to adjust said current fly-height to reach said target fly-height value.
15. The disk drive of claim 14 , further comprising:
a fly-height monitoring section that reports and records a fly-height in real time.
16. The disk drive of claim 14 , wherein said value of DCR changes with a disturbance at said head disk interface wherein said disturbance is selected from the group of disturbances consisting of: disk surface variations, disk waviness, micro-waviness, lube buildup, lubricant moguls, and lube pickup.
17. The disk drive of claim 14 , wherein said resistance measurement section is timely recording a resistance value of said ECS element sensing a clearance change between said head slider and said disk at said head disk interface.
18. The disk drive of claim 14 , wherein said resistance slope to fly-height conversion section is dynamically recording fly-height by generating a resistance slope according to values of ECS resistance and thermal fly-height control (TFC) heater power reported by said head IC.
19. The disk drive of claim 18 , wherein a relationship between a DCR slope and fly-height is determined and stored in said controller IC.
20. The disk drive of claim 14 , wherein a TFC power is reduced for a touchdown detection.