Motor improvement for self-rotating displays

A self-rotating device comprises:

• a body;
• an electric motor carried on said body and driving rotation of said body;
• said electric motor comprises:
• a compass magnet for aligning to an ambient magnetic field;
• at least one field magnet apart from said compass magnet;
• a mechanical linkage fixing an orientation of said at least one field magnet to an orientation of said compass magnet;
• at least one coil mechanically fixed to said body;
• wherein said at least one coil is located to interact with a magnetic field generated by said at least one field magnet;
• and,
• a current supply for supplying commutated current to said at least one coil;
• a light transmissive outer container having an internal cavity shaped and dimensioned to contain an amount of a fluid and a self-powered hollow rotating body immersed in said fluid;
• wherein said outer container is sealed;
• wherein said body comprises:
• an outer wall substantially impermeable to said fluid;
• an inner chamber;
• at least one conduit passing through said outer wall and defining a fluid passageway in fluid communication between said cavity and said inner chamber;
• and,
• a portion of said fluid located in said inner chamber, and an amount of a gas in said inner chamber.