Analog display device with micro-motor drive means

An analog-display device comprising, in combination, indicator means comprising a moveable display member for visibly displaying a position within a range of positions, and a planar micro-motor for driving the display member in response to an externally generated electrical signal, the micro-motor being a stepper motor comprising:

• a substrate;
• stator means for receiving three-phase electrical power to selectively generate electromagnetic fields, comprising (a) circumferentially spaced bifilar micro-coils supported by the substrate and arrayed radially in a first plane about a center point and (b) stator teeth arrayed in a circle in said first plane radially outward of the bifilar micro-coils;
• rotor means for rotation in a second plane parallel to the first plane in response to said electromagnetic fields, comprising circumferentially spaced, elongate ferromagnetic pole members arrayed radially in a planar rotor body about a rotor shaft having an axis of rotation substantially normal to the rotor body and passing through said center point in the first plane, and rotor teeth arrayed in the rotor body in a circle in said second plane radially outward of the pole members in registry with the stator teeth;
• and
• energizing means for selectively passing electrical power to the bifilar micro-coils to generate said electromagnetic fields, comprising concentric power busses supported by the substrate, at least one of the busses corresponding to each of the three current phases, and each of the power busses comprising arcuate segments extending from one bifilar micro-coil to the next bifilar micro-coil of the same current phase;
• wherein the display member of the indicator means is mounted for movement by rotation of the rotor shaft.

An analog gauge in a motor vehicle instrument panel comprising, in combination:

• a mounting base having a display surface, at least a portion of which display surface is visible to an occupant of the vehicle, showing a range of positions corresponding to a range of values;
• an elongate display member having a free end moveable within the range of positions shown on the display surface and a mounted end;
• and
• a planar micro-motor mounted to the display surface for driving the display member in response to an electrical signal, the micro-motor being a stepper motor comprising:
• a substrate;
• stator means for receiving three-phase electrical power to selectively generate electromagnetic fields, comprising (a) circumferentially spaced bifilar micro-coils supported by the substrate and arrayed radially in a first plane about a center point and (b) stator teeth arrayed in a circle in said first plane radially outward of the bifilar micro-coils;
• rotor means for rotation in a second plane parallel to the first plane in response to said electromagnetic fields, comprising circumferentially spaced, elongate ferromagnetic pole members arrayed radially in a planar rotor body about a rotor shaft having an axis of rotation substantially normal to the rotor body and passing through said center point in the first plane, and rotor teeth arrayed in the rotor body in a circle in said second plane radially outward of the pole members in registry with the stator teeth;
• and
• energizing means for selectively passing electrical power to the bifilar micro-coils to generate said electromagnetic fields, comprising concentric power busses supported by the substrate, at least one of the busses corresponding to each of the three current phases, and each of the power busses comprising arcuate segments extending from one bifilar micro-coil to the next bifilar micro-coil of the same current phase;
• wherein the display member is mounted for rotational movement in response to rotational movement in the rotor shaft.