Motor/encoder assembly for tape drives
View Patent ↗A magnetic/encoder assembly has a compact design and combines the features of motor, encoder and chuck locating feature within a single motor housing. The motor/encoder includes a DC brushless motor with an inner magnetic rotor. The motor windings and the commutation electronics are mounted towards the bottom side of a printed circuit board. The rotor of the motor is extended above the surface of the printed circuit board. The extended rotor provides a precision seat for the magnetic wheel with multiple poles. The top surface of the printed circuit board mounts the sensor for the encoder. The extension of the rotor provides the precision mounting surface of the cartridge driving chuck.
1. A tape drive comprising:
a rotor compartment;
means housed within the rotor compartment for coupling a rotor to a tape cartridge rotating a tape cartridge reel, and encoding a position of the rotor, the means including said rotor rotatably mounted within the rotor compartment wherein the rotor includes a first axial end, and a chuck feature at the first axial end;
a magnetic code wheel attached to the rotor to spin with the rotor and located within the rotor compartment;
a magnetic code wheel sensor stationarily positioned within the rotor compartment, which senses rotation of the magnetic code wheel;
a printed circuit stationarily mounted in the rotor compartment, the sensor being mounted in the rotor compartment on the top surface of the printed circuit board, and the magnetic code wheel being mounted on the rotor above the top surface of the printed circuit board; and
a rotatable shaft on which the rotor is fixedly mounted, the shaft extending through the rotor and protruding above the first axial end to form a chuck locating feature.
2. The tape drive of claim 1 , wherein the sensor is a linear hall sensor.
3. The tape drive of claim 1 , wherein the sensor is a magneto-resistive sensor.
4. The tape drive of claim 1 , wherein the magnetic code wheel comprises a magnet-ring holder attached to the rotor, and a magnet-ring mounted to a surface of the magnet-ring holder.
5. The tape drive of claim 4 , wherein the magnet-ring is axially magnetized and has alternating north and south poles around the circumference of the magnetic-ring.