| 摘要 |
PURPOSE:To provide uniform protective resin layer on the surface of optical fibers by a method wherein heating furnace temperature is controlled according to signal detecting variations in speed of optical fiber drawing so that drawing speed is maintained at a specified value. CONSTITUTION:When the temperature of optical fiber base material 3, 4 exceeds the specified value, the rotating speed of capstan 12 increases so as to maintain the diameter of fiber wire 5 at a constant value, and as a result drawing speed increases. At this time, the rotating speed of the capstan 12 is found by detector 15, causing a signal 16 to be output from comparator 16 in proportion to variations in drawing speed. Corresponding to this output signal, power supply from source 17 to electric furnace 2 is reduced. This results in reduced temperature of fiber base material 3, 4. So, the rotating speed of the capstan 12 is reduced so that the diameter of fiber wire 5 is maintained at the specified value, thereby restoring the specified draw speed. When the temperature of the base material 3, 4 is lowered and drawing speed is decreased, the reverse operation occurs to resume the specified drawing speed. |
