Galvanometer with axial symmetry and improved bearing design
AssigneeGSI Lumonics Corporation
InventorDavid C. Brown
Life of this patent
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Abstract
A galvanometer unit comprises a limited-rotation motor, which has axial symmetry of the major motor components including axial placement of the bearings, stator drive coils, and stator back iron with respect to the magnetic center of the rotor, and which employs a cylindrical magnet having significantly uniform properties along its length. The galvanometer employs independently “hard” and “soft” preloaded bearings, which simultaneously minimize axial displacement and account for thermal expansion of the rotor assembly and which improve the overall efficiency of the galvanometer and extend the service life of the bearings.
Claims20
A galvanometer comprising:
- (a) a rotor comprising:
- 1. a permanent magnet armature;
- and
- 2. first and second shafts extending from the armature;
- (b) a load element affixed to one of the shafts;
- (c) a stator having a housing concentric with the rotor, the stator interacting with the flux of the permanent magnet armature;
- (d) a first bearing assembly axially restrained with respect to both the housing and the first shaft, for rotationally supporting the first shaft, in which the first bearing assembly is internally preloaded, with a relatively high spring constant, such that it substantially prevents axial movement of the first shaft during operation;
- and
- (e) a second bearing assembly, with a relatively low spring constant, connected to the housing for rotationally supporting the second shaft,
- whereby substantially all axial thermal expansion of the armature is accommodated by movement of the second shaft.
A galvanometer unit comprising:
- (a) a rotor comprising:
- 1. a permanent-magnet armature having a magnetic center;
- and
- 2. first and second shafts extending from the armature;
- (b) a load element affixed to one of the shafts;
- (c) a stator, concentric with the rotor and having a housing, a back iron portion and including drive coils for generating a magnetic field that interacts with the permanent-magnet armature;
- (d) a first bearing assembly for rotationally supporting the first shaft;
- and
- (e) a second bearing assembly for rotationally supporting the second shaft, wherein the drive coils and back iron are magnetically symmetrically aligned with the magnetic center of the rotor.
Dependencies are inferred from the claim text.