| 摘要 |
PROBLEM TO BE SOLVED: To provide dynamic pressure gas bearing structure simplifying the outer peripheral surface shape of a shaft of a rotation driving part so as to be rotatable stably at high speed, and provide a light deflection scanning device provided with dynamic pressure gas bearing structure. SOLUTION: In dynamic pressure gas bearing structure, a rotation driving part is provided with a cylindrical shaft 1 and a hollow cylindrical sleeve opposed to the shaft 1 while keeping a clearance in a radial direction, and the shaft 1 and the sleeve are formed of silicon nitride group ceramics sintered bodies. The outer peripheral surface 101 of the shaft 1 includes plane parts 105 arranged in at least three places 102, 103, 104 at equal spaces to a circumference along the outer peripheral surface 101. Each plane part 105 is composed of a plurality of single-planes 105a, 105b, 105c formed on the outer peripheral surface 101 of the shaft 1 continuously at a specified angle in a circumferential direction. These single-planes are so formed as to be extended almost parallel with the axial direction of the shaft 1. |
