Limited rotation motor with velocity sensing system
First Claim
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1. In a limited rotation motor comprising:
- a rotor which is elongated in the direction of its axis of rotation and has faces for interaction with stator faces,magnet means extending lengthwise of the rotor and adapted to produce bias flux,stator means extending lengthwise of the rotor constructed to conduct said bias flux between stator faces, thereby to complete with said rotor a magnetic circuit for said bias flux,a drive system comprising a plurality of drive structures extending lengthwise of the rotor, each comprising a drive coil for producing drive flux and a stator constructed to conduct said drive flux between stator faces thereby to complete with said rotor magnetic circuits for said drive flux,the rotor adapted to be driven by interaction of said drive and bias fluxes;
the improvement wherein;
one of said drive structures is shorter in axial dimension than another anda velocity sensor structure is disposed on the same side of the rotor as said shorter drive structure and spaced axially therefrom,said sensor structure comprising a discrete sensor stator associated with a sensing coil and constructed to conduct flux from a magnet means between sensor stator faces, thereby to complete with said rotor a magnetic circuit for said flux,and said sensor coil disposed to receive an induced current in response to modulation of flux in the latter magnetic circuit caused by movement of said rotor,whereby said sensor structure can be compactly arranged with said drive system and produce useful velocity information.
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Abstract
Moving iron limited rotation motors, and recorders employing such motors, in which a velocity sensor structure is axially spaced from a drive structure that is shorter than another drive structure of the drive system. In the preferred embodiment shown, a motor having a pair of diametrically opposite drive structures, the sensor is positioned opposite to the end of the longer drive structure and cooperates with it and a coextensive portion of the rotor in defining flux paths. A pair of permanent magnets extend the full length of the drive-sensor structure, supplying flux to both parts.
33 Citations
10 Claims
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1. In a limited rotation motor comprising:
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a rotor which is elongated in the direction of its axis of rotation and has faces for interaction with stator faces, magnet means extending lengthwise of the rotor and adapted to produce bias flux, stator means extending lengthwise of the rotor constructed to conduct said bias flux between stator faces, thereby to complete with said rotor a magnetic circuit for said bias flux, a drive system comprising a plurality of drive structures extending lengthwise of the rotor, each comprising a drive coil for producing drive flux and a stator constructed to conduct said drive flux between stator faces thereby to complete with said rotor magnetic circuits for said drive flux, the rotor adapted to be driven by interaction of said drive and bias fluxes; the improvement wherein; one of said drive structures is shorter in axial dimension than another and a velocity sensor structure is disposed on the same side of the rotor as said shorter drive structure and spaced axially therefrom, said sensor structure comprising a discrete sensor stator associated with a sensing coil and constructed to conduct flux from a magnet means between sensor stator faces, thereby to complete with said rotor a magnetic circuit for said flux, and said sensor coil disposed to receive an induced current in response to modulation of flux in the latter magnetic circuit caused by movement of said rotor, whereby said sensor structure can be compactly arranged with said drive system and produce useful velocity information. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. In a moving-iron limited rotation motor comprising a ferromagnetic rotor of predetermined length having faces for interaction with stator faces,
a pair of elongated stationary magnets extending along the length of the rotor adapted to produce bias flux, a pair of drive stator structures, each associated with a respective drive coil for producing drive flux, each stator structure constructed to conduct said bias flux relative to said rotor through cooperating rotor and stator pole faces, thereby to complete with said rotor magnetic circuits for said bias flux, and each stator structure constructed to conduct said drive flux relative to said rotor through cooperating rotor and stator pole faces, thereby to complete with said rotor magnetic circuits for said drive flux, the rotor adapted to be driven by interaction of said drive and bias fluxes, the improvement wherein a velocity sensor is provided integral with said rotor, one of said drive stator structures being substantially longer than the other, a discrete sensor stator structure disposed on the same side of the rotor as the shorter of said drive stator structures, spaced from said shorter drive structure and opposed to a portion of said rotor, said magnet and said longer drive stator structure, said sensor stator structure associated with a sensing coil and constructed to conduct flux from said magnets relative to said rotor through cooperating rotor and stator pole faces, thereby to complete with said rotor a magnetic circuit for said flux, and said sensor coil disposed to receive an induced current in response to modulation of flux in the latter said magnetic circuit caused by movement of said rotor,
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10. said sensor thereby compactly sharing said rotor and magnets with the drive structure while enabling its magnetic parameters to be distinguished from those of the drive structure.
Specification