Claims
- 1. A disc drive head testing method usable with a disc drive head testing unit comprising an input lead configured for attachment to a disc drive head under test and an output stage operatively coupled to the input lead and configured to generate an output signal, the method comprising:
determining an unknown electrical property of the head testing unit by:
generating a plurality of output signals at the output stage by consecutively coupling to the input lead each one of a plurality of test devices having known electrical properties and generating an output signal characteristic of the known electrical properties of the test devices and the unknown electrical property of the head testing unit, and computing a head testing unit property by solving for the unknown electrical property based on the output signals generated for each of the known test devices; and for a disc drive head under test,
coupling the head to the input lead; exposing the head to a stored magnetic data pattern to generate a read signal at the input lead; generating a read output signal at the output stage based on the read signal applied to the input lead by the head; measuring an electrical property of the head under test, the measured property differing for different disc drive heads, said difference affecting the generated read output signal; and adjusting the read output signal based on the testing unit property and the measured property to compensate for differences in the measured property.
- 2. The method of claim 1 wherein:
each output signal comprises a frequency-dependent signal, and generating the output signal comprises generating over a range of frequencies.
- 3. The method of claim 2 wherein generating an output signal further comprises generating based on a frequency-variable voltage source providing a known voltage signal over the range of different electrical frequencies.
- 4. The method of claim 1 wherein:
the known electrical properties of each known test device comprise a resistance; and the unknown electrical property of the head testing unit comprises an impedance.
- 5. The method of claim 1 wherein the measured property comprises a resistance of the drive head under test.
- 6. The method of claim 5 wherein adjusting the read output signal comprises scaling the read output signal in proportion to
- 7. The method of claim 1 wherein the output stage comprises an amplifier having an adjustable amplification boost and the method further comprises adjusting the amplification boost based on the measured property.
- 8. The method of claim 7 wherein adjusting the amplification boost comprises selecting amplification boost settings for different ranges of the measured property, the different amplification boost settings being selected to provide a similar output characteristic for different measured properties.
- 9. The method of claim 8 wherein the similar output characteristic comprises a shape of a plotted output signal.
- 10. The method of claim 1 wherein the step of generating a plurality of output signals comprises generating a plurality of output signals using a signal generator.
- 11. The method of claim 1 further comprising determining whether the disc drive head is operational based on the adjusted read output signal.
- 12. A disk drive head testing apparatus comprising:
an input lead configured for attachment to a disk drive head under test; an output stage operatively coupled to the input lead and configured to generate an output signal based on a signal received at the input lead; and circuitry configured to adjust the amplified output signal of the output stage based on an impedance of the head testing unit and a resistance of a disk drive head coupled to the input lead.
- 13. The apparatus of claim 12 further comprising:
circuitry configured to compensate the output signal to reduce gain variations due to variations in resistance of different disk drive heads coupled to the input leads.
- 14. The apparatus of claim 13 wherein said gain variations result from a coupling of the frequency-dependent impedance of the output stage and resistance of disk drive heads attached to the input lead.
- 15. The system of claim 12, wherein:
each output signal comprises a frequency-dependent signal, wherein the output signal is generated over a range of frequencies.
- 16. The system of claim 12 wherein read output signal is adjusted by scaling the read output signal in proportion to
- 17. The system of claim 12 wherein the output stage additionally comprises a preamplifier having an adjustable amplification boost, wherein the amplification boost is adjusted based on the measured property.
- 18. The system of claim 17 wherein the amplification boost comprises amplification boost settings for different ranges of the measured property, the different amplification boost settings being selected to provide a similar output characteristic for different measured properties.
- 19. A disk drive head testing apparatus comprising:
an input lead configured for attachment to a disc drive head under test and an output stage operatively coupled to the input lead and configured to generate an output signal; and means to adjust the output signal based on a known test device property and a measured head testing unit property to compensate for differences in the measured property.
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] This application claims the benefit of the filing date of U.S. provisional application Ser. No. 60/182,029 entitled “Per Head preamplifier Boost Adaptation and Amplitude Correction for Accurate HGA Electrical Test Readings with a Flat Frequency Response,” which was filed on Feb. 11, 2000.
Provisional Applications (1)
|
Number |
Date |
Country |
|
60182029 |
Feb 2000 |
US |