Giant magnetoresistance based nanopositioner encoder

• US 6,940,277 B2
• Filed: 08/28/2003
• Issued: 09/06/2005
• Est. Priority Date: 11/17/2000
• Status: Expired due to Term

• Current Assignee: University of South Florida (State University System of Florida)
• Original Assignee: University of South Florida (State University System of Florida)
• Inventors: Fries, David P.
• Primary Examiner(s): Patidar, Jay
• Application Number:
  US10/651,160
• Publication Number:
  US 20040036469A1
• Time in Patent Office: 740 Days
• Field of Search: 324/207.11, 324/207.2, 324/207.21, 324/207.24, 324/207.25, 324/174
• US Class Current: 324/207.24
• CPC Class Codes: G01D 5/145 influenced by the relative movement between the Hall device and magnetic fields see G01R33/06
• CPC Class Codes: G01D 5/2451 Incremental encoders G01D5/2454 takes precedence
• CPC Class Codes: G01P 13/00 Indicating or recording presence, absence, or direction, of movement electric switches H01H; counting moving objects G06M7/00
• CPC Class Codes: G01P 15/105 by magnetically sensitive devices
• CPC Class Codes: G11B 5/40 Protective measures on heads, e.g. against excessive temperature G11B5/31 takes precedence; protection against wear G11B5/255 ; protective structure of the head: see under structures, e.g. G11B5/3106

Abstract

An encoder (10) for a nanopostioner (24) includes a strip of magnetic bits (18) for producing discrete magnetic fields and a giant magnetoresistor (GMR) (14) which changes in electrical resistance in response to changes in the magnetic fields. The GMR (14) is connected to a mass (12) which moves along a path proximate to the strip of magnetic bits (18). A voltage sensor (20) is connected to the GMR (14) to produce digital signals based on the changes in electrical resistance of the GMR (14). A processor (22) calculates the position of the nanopositioner (24) based on the digital signals.

Claims

1. An encoder (10) for determining position comprising:

a magnetic element (16) producing a magnetic field;

a mass (12) to move along a path and passing through said magnetic field;

a nanopositioner (24) operatively connected to said mass (12) for moving said mass (12);

a giant magnetoresistor (GMR) (14) operatively connected to said mass (12) for changing in electrical resistance in response to changes in said magnetic field produced by said magnetic element (16);

a voltage sensor (20) operatively connected to said GMR (14) for sensing a voltage across said GMR (14);

said magnetic element (16) including a strip of magnetic bits (18) providing discrete magnetic field regions disposed linearly relative to one another along said path; and

said mass (12) and said magnetic bits (18) being supported for movement relative to one another along said path to produce digital signals from said voltage sensor (20).

2. An encoder (10) as set forth in claim 1 further comprising a processor (22) operatively connected to said voltage sensor (20) for determining a position of said nanopositioner (24) based on said digital signals.