| 摘要 |
PROBLEM TO BE SOLVED: To detect the height of the liquid level of a liquid in a liquid chamber, without having to make a large current flow in the liquid. SOLUTION: Light-emitting diodes 44a, 44b of photocouplers 41a, 41b are connected between a COM terminal and an HHH terminal which are connected to an HHH electrode disposed at the liquid chamber, and light emitting diodes 64a, 64b, 64c and 64d of photo couplers 61a-61d are respectively connected between the COM terminal and an HH terminal, an H terminal, an L terminal and an LL terminal. The light-emitting diodes 44a, 44b and 64a-64d are connected with resistances 42a, 42b and 62a-62d in parallel and are connected with resistances 33, 33 and 63a-63d in series, respectively. When respective electrodes are immersed in an electrolytic bath, the light-emitting diodes 44a, 44b and 64a-64d emit lights, corresponding phototransistors 45a, 45b and 65a-65d are made conductive between their collector terminals and emitter terminals. COPYRIGHT: (C)2009,JPO&INPIT
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