| 摘要 |
PURPOSE:To suppress vibrations, noises and the revolving variance of a rotary drum device by increasing the contactless shaft bearing force in the radius direction of the drum by producing the dynamic pressure of a fluid or the magnetic force of a magnet between the outer circumferential side face of a bearing housing part at the center of a fixed drum and the inner circumferential surface part of a recess part of a rotary structure. CONSTITUTION:A rotary drum 5 to which video heads 15 and 15' are fixed is fixed to a rotary shaft 1 via a disk 4, and the shaft 1 is supported rotatably by the bearings set at the center part of a fixed drum 3 and at the lower part of a rotary drum device. The revolving power is given to the shaft 1 by a motor to revolve the drum 5 and the disk 4. Thus the air between the shaft 1 and dynamic pressure structures 22 and 22' as well as a dynamic pressure structure 27 and the inner circumferential surface of the disk 4 flow within a chevron groove 21 of the shaft 1 and the groove 21 of the structure 27 to produce the dynamic pressure between paired rotary and fixed structures respectively. Thus the shaft 1 is held centripetally and with no contact. This produces high dynamic pressure and the stable centripetal force. In addition, both vibrations and noises due to the bearing can be greatly reduced owing to the reduction of solid state contact parts of a shaft supporting part. |
