Write head tester using inductance
AssigneeInfinitum Solutions, Inc.
InventorAlexander M. Taratorin
Life of this patent
Estimating the term…
Abstract
A write head is tested by measuring the effect that magnetic fields have on the inductance of the write head. For example, a perpendicular write head may be placed in a magnetic field with a first angle, e.g., non-parallel and non-perpendicular, to the air bearing surface and the inductance is measured. After altering the angle of the magnetic field the inductance is again tested. In another embodiment, the angles may be parallel and perpendicular to the air bearing surface. The difference in the inductance value can be used to determine a characteristic of the write head, such as the presence of a recording pole. In some embodiments, the inductance may be measured while applying a bias current to the write head while the write head is in an external magnetic field.
Claims15
A method comprising:
- applying a first magnetic field with a first polarity to the write head;
- measuring a first inductance of the write head after the first magnetic field has been removed;
- applying a second magnetic field with a second polarity to the write head, the second polarity being opposite the first polarity;
- measuring a second inductance of the write head after the second magnetic field has been removed;
- using the first inductance and the second inductance to determine hysteresis in the write head;
- and
- recording the determined hysteresis in the perpendicular write head.
An apparatus for testing a write head, the apparatus comprising:
- a means for applying and removing magnetic fields of opposite polarities in a write head;
- an inductance meter configured to be coupled to the write head;
- and
- a processor coupled to the inductance meter and the means for applying and removing magnetic fields, the processor configured to receive a inductance measurements from the inductance meter, the processor comprising a computer-usable medium having computer-readable program code embodied therein for causing the processor to control the means for applying and removing magnetic fields to apply and remove a first magnetic field with a first polarity;
- control the inductance meter to measure a first inductance of the write head after the first magnetic field is removed;
- control the means for applying and removing magnetic fields to apply and remove a second magnetic field with a second polarity that is opposite the first polarity;
- control the inductance meter to measure a second inductance of the write head after the second magnetic field is removed;
- determine hysteresis of the write head based on the first inductance and the second inductance;
- and record the determined hysteresis of the write head.
Dependencies are inferred from the claim text.