| 摘要 |
PURPOSE:To always make a printing condition proper by holding the concn. of an additive to a predetermined value, by detecting the floating and sinking movement of a hydrometer arranged in supply water for use in printing by an actuator, and controlling the injection amount of the additive into the supply water by utilizing the obtained detection signal. CONSTITUTION:The supply water [in which an additive (alcohol) is contained at a predetermined concn.] 2 in a water tank 2 is recirculated through (i) a pipe 3, a water tray 4 and a pipe 6 or (ii) the pipe 3, a cock V, a detection tank 5 and a pipe 8. On the other hand, a hydrometer 10 is supported in the supply water 2 in the detection tank 5 in a freely floatable and sinkable manner through a guide 9 and an actuator ACT (a mark SW is a solenoid valve) is arranged in the notch groove 21 of the protruded piece 22 of the drive part 23 provided to the top part of the hyrometer 10 in a freely settable manner in an up-and-down direction. In the above mentioned apparatus, when the concn. of the additive in the supply water 2 is lowered, the hydrometer 10 is sunk and the actuator ACT is separated from the bottom part 21a of the notch groove 21 to operate the solenoid valve SW and a solenoid valve SV is opened by the signal thereof to inject the additive into the detection tank 5 from a tank 7 and the concn. of the additive in the supply water is always held to a predetermined value. |
