| 摘要 |
PROBLEM TO BE SOLVED: To provide a structure for easily and stably setting two threshold levels. SOLUTION: The level of a detection signal is taken as a reference level L0 [a liquid-less state] when a detection part 30 is not in liquid. Two thresholds L1 [a liquid shortage state] and L2 [a liquid input state] are set by shifting the reference level L0 at a prescribed rate. Liquid detection is performed based on a comparison in level between the thresholds L1 and L2 and the detection signal outputted from the detection part 30. In setting the thresholds, the first threshold L1 is set by shifting the previously set reference level L0 by a first shift rate while setting the second threshold L2 by shifting the reference level L0 by a second shift rate different from the first rate in the same direction as a shift direction from the reference level L0 in setting the first threshold L1. COPYRIGHT: (C)2007,JPO&INPIT |
