Magnetic head measuring apparatus and measuring method applied to the same apparatus

• US 20020130658A1
• Filed: 02/05/2002
• Published: 09/19/2002
• Est. Priority Date: 02/05/2001
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Abe, Masayuki
• Granted Patent: US 6,617,848 B2
• Time in Patent Office: Days
• US Class Current: 324/210
• CPC Class Codes: G01Q 10/06 Circuits or algorithms therefor
• CPC Class Codes: G01Q 60/54 Probes, their manufacture, or their related instrumentation, e.g. holders
• CPC Class Codes: G01R 33/0385 in relation with magnetic force measurements magnetic force microscopes G01Q60/50
• CPC Class Codes: G11B 2005/0013 of transducers, e.g. linearisation, equalisation
• CPC Class Codes: G11B 5/455 Arrangements for functional testing of heads; Measuring arrangements for heads

Abstract

A magnetic head measuring apparatus executes measurement with respect to at least one measurement point on a recording head. The apparatus includes a probe having a magnetic substance, a vibrator which vibrates the probe above the at least one measurement point, a first signal generator which supplies a drive signal to the vibrator, a second signal generator which supplies a current containing a direct current and an alternate current to the recording head to generate a magnetic field from the recording head, a detector configured to detect a signal corresponding to a force interaction that acts on the probe due to the magnetic field generated from the recording head in accordance with the current supplied by the second signal generator, and a measurement unit which measures current dependence of the magnetic field of the recording head from the signal detected by the detector.

Claims

1. A magnetic head measuring apparatus for executing measurement with respect to at least one measurement point on a recording head, comprising:

a probe having a magnetic substance;

a vibrator configured to vibrate said probe above the at least one measurement point;

a first signal generator configured to supply a drive signal to said vibrator;

a second signal generator configured to supply a current containing a direct current (DC) and an alternate current (AC) to the recording head to generate a magnetic field from the recording head;

a detector configured to detect a signal corresponding to a force interaction that acts on said probe due to the magnetic field generated from the recording head in accordance with the current supplied by said second signal generator; and

a measurement unit configured to measure current dependence of the magnetic field of the recording head from the signal detected by said detector.

2. The apparatus according to claim 1, wherein said detector includes:

a deflection detector configured to detect deflection of said probe,

a phase sensitive detector configured to detect a phase shift between output signals from said deflection detector and first signal generator, and

a synchronous detector configured to extract an amplitude component synchronous with the AC from a signal output from said phase sensitive detector.

3. The apparatus according to claim 1, wherein said detector includes:

a deflection detector configured to detect deflection of said probe,

a frequency demodulator configured to detect a frequency of an output signal from said deflection detector, and

a synchronous detector configured to extract an amplitude component synchronous with the AC from a signal output from said frequency demodulator.

4. The apparatus according to claim 3, further comprising a phase controller configured to control a phase of an output signal from said first signal generator on the basis of the output signal from said deflection detector.

5. The apparatus according to claim 1, wherein said measurement unit obtains an image of the magnetic field in terms of a DC current on the basis of the signal detected by said detector.

6. The apparatus according to claim 1, wherein said measurement unit obtains a curve of derivative of the magnetic field in terms of a DC current at an arbitrary measurement point on the recording head on the basis of a signal obtained by said detector by changing a current value of the DC supplied by said second signal generator.

7. The apparatus according to claim 6, wherein said measurement unit obtains a curve of the magnetic field in terms of the DC current at the arbitrary measurement point on the recording head on the basis of the curve of the derivative of the magnetic field in terms of the DC current.

8. The apparatus according to claim 1, wherein the AC supplied by said second signal generator contains an amplitude modulation current.

9. An apparatus according to claim 1, wherein an amplitude value of the AC is not more than 3 mA.

10. The apparatus according to claim 1, wherein

said vibrator includes a cantilever which supports said probe, and

a frequency of the AC is not more than {fraction (1/10)} a resonance frequency of said cantilever.

11. A measuring method applied to a magnetic head measuring apparatus for executing measurement with respect to at least one measurement point on a recording head, said method comprising:

supplying a current containing a direct current (DC) and an alternate current (AC) to the recording head to generate a magnetic field from the recording head;

bringing a probe having a magnetic substance close to the recording head while vibrating the probe;

detecting a signal corresponding to a force interaction that acts on the probe due to the magnetic field generated from the recording head; and

measuring current dependence of the magnetic field of the recording head from the detected signal.

12. The method according to claim 11, wherein in the signal detection, an amplitude component synchronous with the AC is extracted from the signal corresponding to the force interaction.

13. The method according to claim 11, wherein in the measurement, an image of derivative of the magnetic field in terms of a DC current is obtained from the detected signal.

14. The method according to claim 11, wherein in the measurement, a curve of derivative of the magnetic field in terms of the DC current at an arbitrary measurement point on the recording head is obtained on the basis of a signal obtained in the signal detection by changing a current value of the DC supplied.

15. The method according to claim 14, wherein in the measurement, a curve of the magnetic field in terms of the DC current at the arbitrary measurement point on the recording head is obtained on the basis of the curve of the derivative of the magnetic field in terms of the DC current.

16. The method according to claim 11, wherein in the measurement,

a range including a plurality of measurement points on the recording head is scanned by the probe,

at each measurement point, a current value of the DC supplied is changed while keeping scanning stopped, and

the current dependence of the magnetic field of the recording head is measured on the basis of the signal obtained in the signal detection in accordance with a change of the current value of the DC supplied.