| 摘要 |
PURPOSE:To keep the printing quality constant by opening/closing control of the ink passage detecting the ink content between two electrodes arranged in contact with an ink occluding body for supplying ink to a wire. CONSTITUTION:When an A.C. voltage is applied to an electrode 11 as a sensor 16 from the A. C. power source 13, the voltage V1 due to a resistance 15 changes to the voltage V2 via an amplification circuit 17 and a rectifier 18. A comparator 19 compares the voltage with the reference voltage VX corresponding to the quantity of an ink stably contained into an ink occluding body 5 and a printing disabling voltage VY. When V2<=VX, an ink replenishing signal S1 is outputted to open or close an electromagnetic valve 8 through a driver 21 thereby controlling the supply of the ink. When V2<=VY, a printing action stop signal S2 is outputted to actuate an indicator 20. |
