Electricity: measuring and testing – Measuring – testing – or sensing electricity – per se – Magnetic saturation
Reexamination Certificate
2002-06-14
2003-05-20
Le, N. (Department: 2858)
Electricity: measuring and testing
Measuring, testing, or sensing electricity, per se
Magnetic saturation
C324S142000, C324S076770, C324S11700H, C607S066000, C033S361000
Reexamination Certificate
active
06566856
ABSTRACT:
The invention pertains to current sensors and particularly to magnetoresistive (MR) current sensors. More particularly, it pertains to MR sensors having low offsets.
SUMMARY OF THE INVENTION
The present current sensor is a closed-loop, non-contact, fast-responding, wide-bandwidth, field nulling current sensor. This sensor reveals parameters equivalent to other closed-loop approaches such as the closed loop Hall effect current sensor in the related art. It is the use of the MR sensor having a set/reset and offset nulling loop leads to ultra low offsets and ultra low offset drifts over all conditions in current measurement. It also has very low offset drift over wide ranges of operating temperatures. Because of the ultra low offset, the sensor provides very accurate measurements of current. It has an auto-zero offset reduction circuit, which has a separate feedback path to remove offset and offset drift from the circuit. The magnetic signal and offset signals are driven to their respective nulls by independent feedback loops. The offset feedback loop is not used in Hall effect type current sensors. The transient noise and spikes caused by the set/reset circuit are greatly reduced with this new feedback scheme. The sensor has a frequency response from DC to over 150 kHz and has a response time of less than one microsecond.
REFERENCES:
patent: 3482163 (1969-12-01), Peek et al.
patent: 3525041 (1970-08-01), Velsink
patent: 3959724 (1976-05-01), Chana et al.
patent: 4096436 (1978-06-01), Cook et al.
patent: 4097802 (1978-06-01), Mahopac
patent: 4255705 (1981-03-01), Milkovic
patent: 4356446 (1982-10-01), Battocletti
patent: 4395677 (1983-07-01), Peterdorf
patent: 4464625 (1984-08-01), Lienhard et al.
patent: 4482862 (1984-11-01), Leehey
patent: 4682101 (1987-07-01), Cattaneo
patent: 4754219 (1988-06-01), Miklovic
patent: 4823075 (1989-04-01), Alley
patent: 4905117 (1990-02-01), Beg
patent: 4961049 (1990-10-01), Ghislanzoni
patent: 5049809 (1991-09-01), Wakatsuki et al.
patent: 5196784 (1993-03-01), Estes, Jr.
patent: 5293121 (1994-03-01), Estes, Jr.
patent: 5416427 (1995-05-01), Tracewell
patent: 5438257 (1995-08-01), Berkcan
patent: 5632092 (1997-05-01), Blank et al.
patent: 5719494 (1998-02-01), Dettmann et al.
patent: 5726571 (1998-03-01), Guchlu et al.
patent: 6008643 (1999-12-01), Mani et al.
patent: 6029090 (2000-02-01), Herbst
patent: 6252390 (2001-03-01), Black, Jr. et al.
patent: 6411250 (2002-06-01), Oswald et al.
patent: 0286079 (1988-10-01), None
Michael J. Caruso, Tamara Bratland, “A New Perspective on Magnetic Field Sensing,” Honeywell SSEC. Carl H. Smith and Robert Schneider, Nonvolatile Electronics, Inc., SENSORS Dec. 1998.
Michael J. Caruso and Tamara Bratland, “Anisotropin Magnetoresistive Sensors: Theory and Applications”, Honeywell, SSEC, Carl H. Smith and Robert Schneider, Nonvolatile Electronics, Inc. SENSORS Mar. 1999.
U.S. Pat. No. 6,445,171, date Sep. 3, 2002, entitled “A Closed-Loop Magnetoresistive Current Sensor System Having Active Offset Nulling.”
Berndt Dale F.
Lenz James E.
Sandquist David A.
Fredrick Kris T.
Hamdan Wasseem H.
Honeywell International , Inc.
Le N.
LandOfFree
Closed-loop magnetoresistive current sensor system having... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Closed-loop magnetoresistive current sensor system having..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Closed-loop magnetoresistive current sensor system having... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3080855