Richard Joel Stokes

US Patent:

62462334, Jun 12, 2001

Filed:

May 27, 1997

Appl. No.:

8/863339

Inventors:

Neil C. Griffen - Westerville OH
Richard S. Stokes - Westerville OH

Assignee:

NorthStar Technologies Inc. - Westerville OH

International Classification:

G01B 730
G01B 714

US Classification:

32420721

Abstract:

A magnetoresistive sensor for use in a rotary encoder with a drum having a circumference covered with a magnetic track at a predetermined pitch includes a plurality of magnetoresistive elements positioned opposite the drum and connected in a bridge circuit such that when the drum rotates an output signal from the bridge indicates a rotary angle of the drum. The magnetoresistive elements include one or more complementary pairs of elements positioned 180. degree. out of phase. Each of such pair of complementary magnetoresistive elements is connected in one leg of a bridge circuit such that jitter effects caused by asymmetric magnetic fields and physical differences between sensor elements are cancelled. Magnetoresistive sensor element configurations for minimizing the impact of temperature gradients across the magnetoresistive sensor are also disclosed.

US Patent:

63007584, Oct 9, 2001

Filed:

Dec 2, 1999

Appl. No.:

9/452450

Inventors:

Neil C. Griffen - Westerville OH
Richard S. Stokes - Westerville OH

Assignee:

NorthStar Technologies Inc. - Westerville OH

International Classification:

G01B 714
G01B 730
G01R 33025

US Classification:

32420721

Abstract:

A magnetoresistive sensor for use in detecting relative motion between the sensor and a further object bearing an alternating pattern of north/south magnetic poles. The sensor includes one or more pairs of magnetoresistive elements positioned so that each element within a pair magnetically complements the corresponding element in that pair. That is, whenever an element is exposed to a north pole of the magnetic pattern, a corresponding complementary element is exposed to a south pole so as to provide a magnetically complemented output. Such pair of complementary magnetoresistive elements are connected into a bridge circuit such that jitter effects caused by asymmetric magnetic fields and physical differences between sensor elements are cancelled. The quadrature sensor output is frequency multiplied to provide frequency multiplied output signals in quadrature. The sensing arrangement can be used, for example, in the context of a rotary encoder having a drum having a circumference covered with a magnetic track at a predetermined pitch, and may include a plurality of magnetoresistive elements positioned opposite the drum and connected in a bridge circuit such that when the drum rotates an output signal from the encoder indicates rotary motion of the drum.

US Patent:

59007273, May 4, 1999

Filed:

Feb 14, 1997

Appl. No.:

8/799367

Inventors:

Neil C. Griffen - Westerville OH
Richard S. Stokes - Westerville OH
Joseph F. Bioty - Westerville OH

Assignee:

Lake Shore Cryotronics, Inc. - Westerville OH

International Classification:

G01P 3481
G01P 102
G01P 3489

US Classification:

324173

Abstract:

A rotary pulse generator kit for monitoring the rotation of a shaft includes an enclosure capable of accepting two different sensor modules. Each sensor module may include axially aligned magneto-resistive sensing elements that sense magnetic poles imprinted in a pattern on a rotor that rotates with the shaft. Two sensor modules having different incremental pulse output rates may be supplied with the tachometer kit. In this way, the shaft may be monitored by a pair of sensor modules pre-set at different incremental pulse output rates, mounted to the same enclosure.

US Patent:

56546335, Aug 5, 1997

Filed:

May 5, 1995

Appl. No.:

8/435267

Inventors:

Neil C. Griffen - Westerville OH
Richard S. Stokes - Westerville OH
Joseph F. Bioty - Westerville OH

Assignee:

Lake Shore Cryotronics, Inc. - Westerville OH

International Classification:

G01P 3487
G01P 3489
G01P 1300

US Classification:

324174

Abstract:

A tachometer for monitoring the rotation of an output shaft (e. g. of a motor, where the motor is enclosed within a standard NEMA housing), includes an enclosure (e. g. adapted to be secured to an end plate of the motor housing), the enclosure having a radial center and a longitudinal axis which, when the enclosure is secured to the housing, are aligned with a longitudinal axis of the output shaft. The enclosure has at least one mounting surface in a peripheral wall portion thereof, the mounting surface having an aperture formed therein which opens in a radial direction. A sensor module including a pair of axially aligned magneto-resistive sensors is mountable on the mounting surface of the enclosure such that the module protrudes through the aperture with the sensors facing radially inwardly. An annular drum having a pair of magnetic patterns arranged on a peripheral end surface thereof is operatively fixed on the motor output shaft via a hub member such that the magnetic patterns on the drum are automatically aligned with the sensors and radially spaced therefrom by a predetermined radial gap when the drum is fixed to the output shaft and the enclosure is mounted on the end plate in an operatively assembled relationship.

US Patent:

56800428, Oct 21, 1997

Filed:

Dec 30, 1994

Appl. No.:

8/366580

Inventors:

Neil C. Griffen - Westerville OH
Richard S. Stokes - Westerville OH

Assignee:

Lake Shore Cryotronics, Inc. - Westerville OH

International Classification:

G01B 730
G01B 714

US Classification:

32420721

Abstract:

A magnetoresistive sensor for use in a rotary encoder having a drum having a circumference covered with a magnetic track at a predetermined pitch includes a plurality of magnetoresistive elements positioned opposite the drum and connected in a bridge circuit such that when the drum rotates an output signal from the bridge indicates a rotary angle of the drum. The magnetoresistive elements include one or more complementary pairs of elements positioned 180. degree. out of phase. Each of such pair of complementary magnetoresistive elements is connected in one leg of a bridge circuit such that jitter effects caused by asymmetric magnetic fields and physical differences between sensor elements are cancelled.

US Patent:

52931250, Mar 8, 1994

Filed:

Jan 17, 1992

Appl. No.:

7/822016

Inventors:

Neil C. Griffen - Westerville OH
Richard S. Stokes - Westerville OH
Joseph F. Bioty - Westerville OH

Assignee:

Lake Shore Cryotronics, Inc. - Westerville OH

International Classification:

G01P 3487
H02K 1100

US Classification:

324173

Abstract:

A tachometer for monitoring the rotation of an output shaft (e. g. of a motor, where the motor is enclosed within a standard NEMA housing), includes an enclosure (e. g. adapted to be secured to an end plate of the motor housing), the enclosure having a radial center and a longitudinal axis which, when the enclosure is secured to the housing, are aligned with a longitudinal axis of the output shaft. The enclosure has at least one mounting surface in a peripheral wall portion thereof, the mounting surface having an aperture formed therein which opens in a radial direction. A sensor module including a pair of axially aligned magneto-resistive sensors is mountable on the mounting surface of the enclosure such that the module protrudes through the aperture with the sensors facing radially inwardly. An annular drum having a pair of magnetic patterns arranged on a peripheral end surface thereof is operatively fixed on the motor output shaft via a hub member such that the magnetic patterns on the drum are automatically aligned with the sensors and radially spaced therefrom by a predetermined radial gap when the drum is fixed to the output shaft and the enclosure is mounted on the end plate in an operatively assembled relationship.