DYNAMIC PRESSURE BEARING DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a dynamic pressure bearing device capable of generating a good dynamic pressure even without forming any concave separating groove.

SOLUTION: The dynamic pressure bearing device 10 for use in a polygon mirror rotational driving device is structured so that a dynamic pressure generation part 31 where a recess 35 to maximize the dimension of a micro-gap 32 formed in the area to the peripheral surface of a rotary shaft 21 and a projection 37 to minimize the dimension of the micro-gap 32 extending in the axial direction is formed on the inside surface of a bearing sleeve 15. The recess 35 and projection 37 are adjacent to each other in the circumferential direction and assume a stepped shape. The edge part 351 of the recess 35 forms a slant edge member where the angle part 352 on the side with a lubricating fluid flowing thereto when the rotary shaft 21 rotates in the direction of arrow r is acute, and the region adjoining thereto is furnished with a genuine round part 36 where the dimension of the micro-gap 32 is identical to the part where the projection 37 is formed.

COPYRIGHT: (C)2003,JPO