| 摘要 |
PURPOSE:To obtain a stable rotating characteristic without any pestle-like movement by forming herringbone grooves on respective capstan shaft portions of upper and lower dynamic pressure fluid bearing portions. CONSTITUTION:A capstan shaft 2 is supported by dynamic pressure fluid bearing portions 6, 7 provided with upper and lower herringbone grooves 10a, 10b. By using a viscous oil fluid like grease as a dynamic pressure fluid, a fluid ring is formed on the periphery of the curved portion of the herringbone groove to hold the capstan shaft at the center thereof. In this case, a small diameter such as a capstan shaft can obtain sufficient dynamic pressure. For example, the oil pressure (grease pressure) for holding the capstan shaft at the center thereof can be easily set about capstan 1kg, and even if the side pressure of 500g is applied to the capstan by a pinch roller, the capstan shaft can be held at the center thereof satisfactorily. |
