Calibrating read sensors of electromagnetic read-write heads

Patent metadata

Field	Value
Publication number	US-10656232-B2
Application number	US-201414498982-A
Country	US
Kind code	B2
Filing date	Sep 26, 2014
Priority date	May 3, 2011
Publication date	May 19, 2020
Grant date	May 19, 2020

Abstract

Described are embodiments to calibrate read sensors, which in turn may ensure that the equipment utilized to detect antigens is reliable and accurate. If it is determined that a read sensor is degraded a method of calibrating a read sensor of a read head may be used.

First claim

What is claimed is:

1. A method of calibrating a magnetic read sensor, the method comprising:
measuring a first resistance of said magnetic read sensor upon an application of a forward bias current through said magnetic read sensor;
measuring a second resistance of said magnetic read sensor upon an application of a reverse bias current through said magnetic read sensor;
determining, using a hardware processor, a calibration constant based on at least said first measured resistance, said second measured resistance, and at least one of the applied bias currents;
storing said determined calibration constant for said magnetic read sensor in memory;
sweeping a head module having said magnetic read sensor over at least one nanoparticle to obtain a read response of said magnetic read sensor to said at least one nanoparticle; and
adjusting said read response from said magnetic read sensor of said at least one nanoparticle based on said determined calibration constant for calibrating said magnetic read sensor,
wherein measuring said first resistance of said magnetic read sensor upon application of said forward bias current to said magnetic read sensor includes measuring a plurality of first resistances of said magnetic read sensor upon an application of a plurality of forward bias currents to said magnetic read sensor, wherein said plurality of first resistances corresponds to said plurality of forward bias currents,
wherein measuring said second resistance of said magnetic read sensor upon application of said reverse bias current to said magnetic read sensor includes measuring a plurality of second resistances of said magnetic read sensor upon application of an application of a plurality of reverse bias currents to said magnetic read sensor, wherein said plurality of second resistances corresponds to said plurality of reverse bias currents,
wherein determining said calibration constant is based on said plurality of first measured resistances and said plurality of said second measured resistances,
wherein said at least one nanoparticle is positioned at a known location along a calibration trench of a calibration assembly,
wherein said head module includes a plurality of magnetic read sensors,
wherein said calibration assembly includes a greater number of calibration trenches than a number of said plurality of magnetic read sensors.

2. The method of claim 1 , wherein said forward bias current and said reverse bias current have the same magnitude, wherein said plurality of magnetic read sensors are included in an apparatus, wherein calibrating said magnetic read sensors in said array achieves a uniform read response from said magnetic read sensors, wherein sweeping said head module over said at least one nanoparticle includes:
for each of said at least one nanoparticle, sweeping said head module along a y-axis of said calibration assembly having said at least one nanoparticle,
wherein each of said at least one nanoparticle is at a y-axis location along said calibration assembly,
wherein said y-axis location is known prior to sweeping said head module over said at least one nanoparticle,
wherein magnetic properties of each of said at least one nanoparticle is known.

3. The method of claim 1 , comprising: determining whether the determined calibration constant is in a predefined acceptable calibration constant range; and repairing or replacing said magnetic read sensor in response to determining that the calibration constant is not in said predefined acceptable calibration constant range, wherein said determined calibration constant for said magnetic read sensor is stored in memory in response to determining that the calibration constant is in said predefined acceptable calibration constant range.

4. The method of claim 1 , wherein said step of determining said calibration constant, K, based on said at least: said first measured resistance R mr (I mr ), said second measure resistance R mr (−I mr ), and at least one of the applied bias currents is given by the equation:

K
≈

R
mr

⁡

(

I
mr

)

-

R
mr

⁡

(

-

I
mr

)

2
⁢

I
mr

⁢

R
mr

⁡

(

I
mr

)

where I mr is the applied forward bias current and where −I mr is the reverse applied bias current.

5. The method of claim 1 , wherein said step of determining said calibration constant, K, based on said plurality of first measured resistances R mr (I mr ) and said plurality of second measure resistances, R mr (−I mr ) is given by the equation:

K
=

∑

R

pn
⁢

⁢
I

⁡

(

I
mr

)

N
m

where N m is the number of said measurements, where I nn is the applied forward bias current and where −I mr is the reverse applied bias current, and where R pnI (I mr ) is defined as:

R
pnI

⁡

(

I
mr

)

=

R
mr

⁡

(

I
mr

)

Assignees

• IBM

Inventors

• Berman David
• Boday Dylan J
• Iben Icko E T
• Imaino Wayne I
• Schwartz Stephen L
• Topol Anna W
• Winarski Daniel J

Classifications

• G01N27/72

  by investigating magnetic variables · CPC title

• G01N27/04

  by investigating resistance · CPC title

• G01N33/53

  Immunoassay; Biospecific binding assay; Materials therefor · CPC title

• G01R33/0035

  Calibration of single magnetic sensors, e.g. integrated calibration · CPC title

• G01R33/1207 Primary

  Testing individual magnetic storage devices, e.g. records carriers or digital storage elements (functional testing G06F11/00, G06F11/28) · CPC title