Patent ID: 8693137

Claim:
A fluid dynamic bearing unit comprising: a hub-side encircling member that encircles a shaft; a shaft holder formed with a shaft hole into which a first end of the shaft is fitted to fix the shaft; a base-side encircling member which is fixed to the shaft holder and which encircles the hub-side encircling member; a rod encircling member which encircles a second end side of the shaft and which is fixed to the shaft; and a ring member which is fixed to the hub-side encircling member and which encircles the rod encircling member; wherein: a lubricant is present between the hub-side encircling member and the shaft, the hub-side encircling member and the shaft holder, the hub-side encircling member and the base-side encircling member, the hub-side encircling member and the rod encircling member, and the rod encircling member and the ring member, respectively; a radial dynamic pressure groove is formed in one of an inner circumference surface of the hub-side encircling member and an outer circumference surface of the shaft; a first air-liquid interface of the lubricant is in contact with an inner circumference surface of the base-side encircling member; and a second air-liquid interface of the lubricant is in contact with an inner circumference surface of the ring member.