| 摘要 |
PURPOSE:To stably indicate value approximately corresponding to levels, by inputting the OR signals of both output of an imitation wave receiving pulse generating circuit and a wave receiving circuit to a time difference detecting circuit when detecting noises. CONSTITUTION:When noise signals are continuously generated during a period that sends out ultrasonic waves toward a lower portion of the inside of a hopper, noise detecting circuits 23, 24 are operated and a FF25 is set, pulses g are input to a FF12 through an AND26 and an OR27 from an imitation wave receiving pulse generating circuit 22, and this device is brought to a condition that cannot receive waves during the next wave sending period. However, the FF12 is reset by regular wave receiving signals or the pulses g because noise signals are generated at random or rarely, and the output value of a measuring counter 14 becomes to value corresponding to levels in the hopper approximately accurate. A pointer of an indicator 21 is stabilized and value approximately corresponding to levels can be indicated because noises rarely generated have not great influence by the leveling function of a damper circuit 19. |
