System for sensing the angular position of a rotatable member using a hall effect transducer
First Claim
1. Apparatus for sensing the angular position of a shaft of a tension arm supported by a housing for rotation through a preselected angle of less than 360°
- comprising;
a circular magnet of selected circumference having a pair of north-south magnetic poles selectively induced therein for generating an arcuate magnetic field thereabout, the magnet being coaxially secured for rotation with the tension arm through the preselected angle of less than 360°
;
magnetic field transducing means selectively secured to the housing in close and constant proximity to the circumference of the circular magnet, and at a preselected position in the magnetic field between the north-south magnetic poles corresponding to a preselected center angular position of the tension arm; and
circuit means including offset adjusting amplifier means responsive to the magnetic field transducing means for supplying a preselected null voltage when the tension arm is at the preselected center angular position, and a linearly varying voltage indicative of the degree of rotation of the tension arm within said preselected angle of less than 360°
when the arm is angularly displaced from the preselected center angular position.
3 Assignments
0 Petitions
Accused Products
Abstract
Angular rotation of a member, such as the shaft of a tension arm assembly, is sensed by the combination of a circular type of magnet secured to the rotatable member and selectively polarized relative to its diameter to define a magnetic north-south pole pair, and a stationary Hall Effect transducing device secured in close and constant proximity to the ring magnet. A circuit coupled to the transducing device includes offset and amplification stages. In a preferred embodiment, the Hall Effect transducing device is located in the region of a magnetic null of the field generated by the magnetic poles, when the rotatable member is in a selected angular position. The constant gap between the transducing device and the circular magnet optimizes the generation of a linear output via the circuit, to accurately sense the member rotation.
-
Citations
10 Claims
-
1. Apparatus for sensing the angular position of a shaft of a tension arm supported by a housing for rotation through a preselected angle of less than 360°
- comprising;
a circular magnet of selected circumference having a pair of north-south magnetic poles selectively induced therein for generating an arcuate magnetic field thereabout, the magnet being coaxially secured for rotation with the tension arm through the preselected angle of less than 360°
;magnetic field transducing means selectively secured to the housing in close and constant proximity to the circumference of the circular magnet, and at a preselected position in the magnetic field between the north-south magnetic poles corresponding to a preselected center angular position of the tension arm; and circuit means including offset adjusting amplifier means responsive to the magnetic field transducing means for supplying a preselected null voltage when the tension arm is at the preselected center angular position, and a linearly varying voltage indicative of the degree of rotation of the tension arm within said preselected angle of less than 360°
when the arm is angularly displaced from the preselected center angular position. - View Dependent Claims (2, 3)
- comprising;
-
4. Apparatus for sensing the angular position within a preselected angle of a rotatable member supported by a housing, the apparatus having annular magnet means coaxially secured for rotation with the rotatable member and including a magnetic pole pair for generating a magnetic field of corresponding arcuate length about the magnet means, comprising:
-
magnetic field transducing means including a Hall Effect device secured in close and constant proximity to a given surface of the magnet means to provide a constant gap therebetween, said Hall Effect device being selectively disposed within the magnetic field between adjacent magnetic poles thereof when the rotatable member is at a preselected angular position; said Hall Effect device further being disposed in a magnetic null region between the magnetic poles of the magnetic field in angular coincidence with the preselected angular position of the rotatable member; circuit means including offset adjusting means coupled to the magnetic field transducing means for generating a substantially linear range of voltages indicative of corresponding angular deviations of the tension arm from the preselected annular position; and said offset adjusting means being set at a preselected nulled voltage corresponding to a zero point in the slope in the linear range of voltage when the rotatable member is at the preselected angular position. - View Dependent Claims (5, 6, 7, 8, 9)
-
-
10. Apparatus for sensing the angular position of a rotatable member supported by a housing, comprising:
-
magnet means of preselected annular length, coaxially secured for rotation with the rotatable member and having a magnetic pole pair for generating a magnetic field of corresponding arcuate length about the magnet means; wherein the magnet means includes a ring magnet having a selected portion removed from the cross section thereof to define confronting ends of the ring magnet; magnetic field transducing means secured in constant proximity to a given surface of the magnet means at a preselected location within the arcuate length of the magnetic field when the rotatable member is at a preselected angular position; wherein the magnetic field transducing means is a Hall Effect device secured in close and constant proximity relative to the magnet means to provide a constant gap therebetween, said Hall Effect device being selectively disposed within the magnetic field between adjacent magnetic poles thereof and disposed in the close and constant proximity to the ring magnet in diametrically opposed relation to the selected removed portion when the rotatable member is at the preselected angular position; and circuit means including offset adjusting means coupled to the magnetic field transducing means for generating a substantially linear range of voltages indicative of corresponding angular positions of the rotatable member; and wherein the offset adjusting means is set at a preselected nulled voltage when the rotatable member is at the preselected angular position.
-
Specification