Rotation supporting device of a polygon mirror

A rotation supporting device of a polygon mirror, comprising:

• a stationary shaft provided with a shaft sleeve around its outer circumference;
• a rotary assembly rotatably mounted around the outer circumference of the shaft sleeve and having an outer circumferential surface in the radial direction of a polygon made to serve as mirror surfaces and a magnet member for generating a torque;
• an electromagnetic coil assembly disposed in the stationary section oppositely facing the magnet member;
• and
• at least one thrust plate suppressing the axial movement of the rotary assembly,
• said rotary assembly having a first rotor rotatably mounted around the outer circumference of the shaft sleeve, an intermediate ring shrink-fitted around the outer circumference of the first rotor, a second rotor having an outer circumferential surface in the radial direction of a polygon made to serve as mirror surfaces and secured around the outer circumference of the intermediate ring and a yoke disposed adjacent to one of the ends of the second rotor and secured to the first rotor or around the outer circumference of the intermediate ring, wherein the yoke is adhered with a magnet member and the amount of elastic deformations of the intermediate ring is larger than that of the first rotor and smaller than that of the second rotor.

A rotation supporting device of a polygon mirror, comprising:

• a stationary shaft provided with a shaft sleeve around its outer circumference;
• a rotary assembly rotatably mounted around the outer circumference of the shaft sleeve and having an outer circumferential surface in the radial direction of a polygon made to serve as mirror surfaces and a magnet member for generating a torque;
• an electromagnetic coil assembly disposed in the stationary section oppositely facing the magnet member;
• and
• at least one thrust plate suppressing the axial movement of the rotary assembly,
• said rotary assembly having a first rotor rotatably mounted around the outer circumference of the shaft sleeve, a second rotor having an outer circumferential surface of a polygon made to serve as mirror surfaces and disposed around the outer circumference of the first rotor, and a yoke being disposed adjacent to one of the ends of the second rotor and secured around the outer circumference of the first rotor, said yoke being adhere with the magnet member, and the second rotor and the yoke being integrally secured by securing means.

A rotation supporting device of a polygon mirror, comprising:

• a stationary shaft provided with a shaft sleeve around its outer circumference;
• a rotary assembly rotatably mounted around the outer circumference of the shaft sleeve and having an outer circumferential surface in the radial direction of a polygon made to serve as mirror surfaces and a magnet member for generating a torque;
• an electromagnetic coil assembly disposed in the stationary section oppositely facing the magnet member;
• and
• at least one thrust plate suppressing the axial movement of the rotary assembly,
• said rotary assembly having a first rotor rotatably mounted around the outer circumference of the shaft sleeve, a cylindrical yoke with a flange secured around the outer circumference of the first rotor, and a second rotor having an outer circumferential surface of a polygon made to serve as mirror surfaces and disposed around the cylindrical portion of the yoke,
• said yoke being adhere with the magnet member, and
• the second rotor and the yoke being integrally secured by securing means.