BALL BEARING AND PIVOT BEARING DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a ball bearing capable of effectively preventing contamination of a hard disk drive device by a simpler structure, and a pivot bearing device.SOLUTION: An inner periphery 24 of a seal 22 is elongated to the inside of a peripheral groove 33 of an outer periphery 32 of an inner ring 11, and a labyrinth structure 37 is formed of a cavity between the peripheral groove 33 and the inner periphery 24 of the seal 22. Thus, a space between a shaft 6 and a sleeve 7 can be functionally cut off from the outside, and a simple structure can prevent contaminants such as out gas and out particles from being discharged to the outside from a pivot bearing device 1.