Permanent magnet type motor and X-ray computed tomography apparatus

An X-ray computed tomography apparatus comprising:

• a stationary tubular frame having a cross section formed in a substantially tapered shape with respect to a tube axis;
• a bearing arranged at a small diameter portion of the stationary tubular frame;
• a rotational tubular frame which is connected to a movable side of the bearing at one end side thereof and which is formed to have a substantially tapered cross section with respect to the tube axis;
• an X-ray tube mounted on the rotational tubular frame;
• an X-ray detector which detects an X-ray that is emitted from the X-ray tube and transmitted through a target to be inspected;
• a rotational position detecting device which detects a rotational position of the X-ray tube in response to the rotation of the rotational tubular frame;
• a computer section which reconstructs tomographic image data on the target to be inspected based on an output of the X-ray detector and a rotational position of the X-ray tube detected by the rotational position detecting device;
• a ring shaped rotor having a rotor core and a permanent magnet disposed and fixed at a link portion of the rotational tubular frame, the permanent magnet being adopted to rotate the rotational tubular frame, the permanent magnet configuring a plurality of magnetic poles on an outer periphery side of the rotor core;
• a stator which is at an outer periphery side of the rotor and which is fixed with respect to an inner periphery face of the stationary tubular frame via a predetermined gap from the rotor;
• and
• a magnetic pole position detecting device which detects a magnetic pole position of the rotor;
• a slip ring disposed and fixed at a large diameter portion of the rotational tubular frame, the rotational tubular frame fixed in abutment with the rotor core, the slip ring configured to supply power to the X-ray tube.