| 摘要 |
PURPOSE:To stabilize a revolving speed in a short time by selecting an advance rate and a return rate by a difference to a designated revolving speed, and adjusting a flow rate little by little by always returning a valve after advancing it. CONSTITUTION:A light reflecting zone is provided on the outside circumference of a rotor 2, a light of a light emitting element 8 is irradiated to said zone, and its reflected light is photodetected by a photodetector 9. A pulse from this rotation detector is counted by a frequency counter 10, and a revolving speed of a sample tube 1 is obtained. A designated revolving speed is inputted from a keyboard, etc., a changeover valve 6 is opened by a start signal S, and also a three phase pulse oscillator 12 is started. A central control device 11 compares a detecting signal from said counter 10 with a designating signal R0 and derives a difference D. A memory in this device 11 stores a table in which an advance rate and a return rate are set at every step by magnitude of said difference D, and basing on it, a flow rate control valve 7 is advanced and also returned, and its opening is adjusted. In this regard, the return rate is always smaller than the advance rate. |
