Rotary table device

A rotary table device comprising:

• a bed disposed at a predetermined location;
• a disk-shaped table rotatably mounted on the bed via a bearing;
• and a motor for rotating the table,
• wherein the motor includes an armature assembly on a primary side of the motor and a field magnet on a secondary side of the motor, the armature assembly including a plurality of armature coils each of which is a three-phase, core-less, flat coil wound in an annular shape and which are circumferentially arranged in an annular recess formed in a top surface of the bed, and the field magnet including a plurality of plate-shaped magnets which are circumferentially arranged in an annular recess formed in a bottom surface of the table such that the magnets face the armature coils and provide N and S poles alternatingly in a circumferential direction,
• wherein the table has a lower part having the bottom surface on which the field magnet is disposed and facing the bed, and a placement part which is integrally formed with the lower part and to which a counterpart member is attached, and
• wherein the rotary table device further comprises:
• a ring member disposed around the lower part of the table and extending over the entire circumference of the lower part;
• a ring scale provided over the entire outer circumferential surface of the ring member;
• and a sensor disposed on the bed so as to read the ring scale.