Permanent magnetic means for positioning a rotatable element to a preselected position
First Claim
1. In a system comprising an angularly rotatable shaft and mounting means for said shaft, wherein the improvement comprises said shaft being mounted free of any spring restraint and free of any torsion bar restraint, first permanent magnet means fixedly mounted with respect to said shaft, second and third permanent magnet means fixedly mounted with respect to said mounting means, said second and third permanent magnet means disposed on opposite sides of said first permanent magnet means, said second and third permanent magnet means being poled so as to repel said first permanent magnet means toward a position intermediate said second and third permanent magnet means.
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Abstract
Permanent magnets are employed to continually urge an rotatable element, such as an oscillating, motor-driven shaft toward a preselected position. When the torque from the motor becomes minimal or is removed, the shaft is returned to a pre-selected, or rest, position. A magnet is disposed on the rotatable shaft and two additional magnets, one disposed on each side of the first magnet, constantly repel it toward a location between the two additional magnets. Such constant repelling is useful in scanners, light-choppers and the like and helps to achieve a harmonic-like motion. In a laser scanner, when the shaft is returned to its preselected position, the radiation is undeflected from a preselected axis. The magnets take the place of springs and are superior to them in precision, length of life and in ease of installation and adjustment.
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Citations
24 Claims
- 1. In a system comprising an angularly rotatable shaft and mounting means for said shaft, wherein the improvement comprises said shaft being mounted free of any spring restraint and free of any torsion bar restraint, first permanent magnet means fixedly mounted with respect to said shaft, second and third permanent magnet means fixedly mounted with respect to said mounting means, said second and third permanent magnet means disposed on opposite sides of said first permanent magnet means, said second and third permanent magnet means being poled so as to repel said first permanent magnet means toward a position intermediate said second and third permanent magnet means.
- 9. In a scanner having a shaft, means for mounting said shaft with respect to a base, a prime mover disposed to torque said shaft and to cause said shaft to oscillate in response to electrical signals, a mirror fixedly mounted with respect to said shaft, said mirror adapted to reflect radiation and to oscillate through an angle due to the oscillation of said shaft, wherein the improvement comprises first permanent magnet means fixedly attached with respect to said oscillating shaft, second and third permanent magnet means fixedly attached with respect to said base and disposed on respective sides of said first permanent magnet means therefore said shaft is mounted free of any spring restraint and free of any torsion bar restraint and said second and third permanent magnet means being magnetically disposed to repel said first permanent magnet means toward a preselected position between said second and third permanent magnets.
- 15. In a radiation scanner comprising a stepper motor having a housing, mounting bracket means, said housing adjustably, rotatably mounted to said bracket means, said motor adapted to be driven by electrical signals, a shaft angularly driven by said stepper motor, a mirror disposed on said shaft and adapted to reflect radiation and adapted to sweep through an angle when said motor is driven by said signal, wherein the improvement comprises a first permanent magnet means disposed on said shaft, second and third permanent magnet means fixedly disposed with respect to said bracket means, on opposite sides of said first permanent magnet means whereby said shaft is mounted free of any spring restraint and free of any torsion bar restraint, said second and third permanent magnet means magnetically disposed to repel said first permanent magnet means, free of any spring restraint and free of any torsion bar restraint, to an approximately central position between said second and third permanent magnet means, said stepper motor housing being rotatably adjustable to a fixed position to provide a desired angle of sweep of said first magnet between said second and third permanent magnet means when said motor is driven by said electrical signals, whereby the angle of sweep of said mirror is also provided.
- 20. In a scanner wherein radiation may be reflected by a movable element, the improvement comprising scan return means comprising first permanent magnet means disposed on said movable element, additional permanent magnet means fixedly disposed in proximity on both sides of said first permanent magnet means so as to magnetically repel said first permanent magnet means, and thereby, said movable element, toward a preselected position and wherein said movable element is mounted with no spring restraint and with no torsion bar restraint.
- 23. In a system in which a shaft is adapted to be driven in an oscillating manner by prime mover means, mounting means for mounting said prime mover means, the improvement comprising mounting said shaft with no spring restraint and with no torsion bar restraint, magnetic repelling means for providing harmonic-like motion of said shaft, said magnetic repelling means comprising first permanent magnet means fixedly mounted with respect to said shaft and thereby moved through an arc, second and third permanent magnet means fixedly mounted with respect to said mounting means, said second and third permanent magnet means disposed on opposite sides of said first permanent magnet means, said second and third permanent magnet means being poled so as to repel said first permanent magnet means toward a position intermediate said second and third permanent magnet means.
Specification