Flying head with adjustable actuator load
AssigneeDigital Papyrus Corporation
InventorsJohn S. Berg, Neville K. S. Lee
Life of this patent
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Abstract
A flying head mechanism includes a flying head, a suspension and an actuator which applies a load force through the suspension. The load force applied by the actuator is adjustable while the head is in operation. The actuator may actively control load force as part of a feedback loop which maintains the flying head at a constant flying height. One embodiment disclosed includes a voice coil actuator. In embodiments using an optical flying head, a conventional focus sensor may provide a signal indicative of flying height, since the focus signal inherently indicates flying height error.
Claims32
A flying head mechanism having a controllable load force, for flying an optical head at a flying height between a minimum glide height which is just greater than a height of asperities on a recording medium and a height at which evanescent wave coupling at a wavelength of interest occurs, the mechanism comprising:
- a suspension;
- an optical head having an air bearing surface and a solid inmersion lens (SIL), the head being mounted by the suspension such that relative motion between a surface of the recording medium and the air bearing surface will cause an air bearing to develop therebetween;
- a force actuator, connected to the suspension, to apply an adjustable load force to the head through the suspension in opposition to a separating force generated by the air bearing, the force actuator having a control input to receive a control signal and being responsive to the control signal to adjust the load force;
- and
- a controller having a control output, connected to the control input of the force actuator, that carries the control signal, the controller generating the control signal, to cause the actuator to produce a load force which acts to substantially maintain the head at the flying height between the minimum glide height just greater than the height of asperities above the surface of the recording medium and the height at which evanescent wave coupling at the wavelength of interest occurs.
A flying head mechanism having a controllable load force, for flying an optical head at a flying height between a minimum glide height which is just greater than a height of asperities on a recording medium and a height at which evanescent wave coupling at a wavelength of interest occurs, the mechanism comprising:
- a head having a solid inmersion lens (SIL) and further having an air bearing surface oriented relative to a surface of the recording medium such that relative motion between the air bearing surface and the recording medium surface causes an air bearing to develop therebetween;
- and
- a load force controller, coupled to the head, to apply a load force in opposition to a separating force generated on the head by the air bearing, the load force controller including a sensor to measure a flying height and minimum glide height of the head, the load force controller being configured to vary the load force to maintain a constant separation between the air bearing surface and the recording medium surface greater than the minimum glide height just greater than the height of asperities on the recording medium surface and less than the height at which evanescent wave coupling at the wavelength of interest occurs.
A method of controlling a load force applied to a flying optical head while using the flying optical head to reproduce information recorded on a recording medium, the method comprising steps of:
- measuring a flying height of the head above an information track of the recording medium;
- determining whether the measured flying height is less than or equal to a minimum glide height just greater than a height of asperities on the recording medium;
- adjusting the load force applied to the head when the measured flying height is found less than or equal to the minimum glide height in the step of determining;
- and
- simultaneously with the foregoing steps, reproducing information recorded on the recording medium using a solid inmersion lens (SIL) carried by the flying optical head to evanescently couple an optical signal into the recording medium.
A method of loading a flying optical head on a medium, comprising steps of:
- applying a load force to the head;
- and
- dynamically varying the load force by means of a controller in response to varying operating conditions to maintain a substantially constant flying height greater than a minimum glide height just greater than a height of asperities on the medium and less than a height at which evanescent wave coupling by a solid inmersion lens (SIL) carried by the head at a wavelength of interest occurs while the head retrieves information from the medium by evanescently coupling an optical signal into the medium.
A flying head mechanism comprising:
- a flying optical head carrying a solid inmersion lens (SIL);
- a sensor that detects a flying height of the head relative to a minimum glide height just greater than a height of asperities on a medium;
- and
- means for applying a load force to the head that varies in accordance with the detected flying height to maintain the flying height of the flying head greater than the minimum glide height just greater than the height of asperities on the medium and less than a height at which evanescent wave coupling at a wavelength of interest occurs.
Dependencies are inferred from the claim text.