Abstract: A charge and deflection control type ink jet printer in which at least an ink jet head section, a charging section and a deflecting section are configured in a single replaceable module, or unit. The user of the printer may replace the module without the help of a serviceman. The replaceable unit is further provided with an ink ejection adjusting mechanism, a deflection efficiency adjusting device, an a drive efficiency adjusting device.

Abstract: An ink-jet printer includes an ink-jet head assembly which has a modular structure. The head assembly includes a generally bathtub-shaped bottom case in which an ink head for ejecting a series of charged ink droplets is mounted and a pair of top and bottom deflection electrodes is also mounted. The head assembly also includes a similarly bathtub-shaped top case which is mounted on the bottom case upside down to define a substantially enclosed space therebetween. The ink head is supported so as to be adjustable in orientation. And, one end of the ink head is supported as a pivotal point so that the other free end may be oriented in any desired direction. In another structure, a print head assembly is detachably mounted on a carriage and the print head assembly includes an inner ink mist absorbing member formed with a slit and formed from a metal. A carriage cover is detachably mounted on the carriage to cover the print head assembly set in position.

Abstract: A device for detecting viscosity of a liquid which varies with time includes a first tank provided with an overflow section for maintaining a predetermined liquid height, and a second tank fluidly communicated to the first tank and provided with a restricted outlet, or orifice. While a liquid is circulated through the two tanks by a pump, a height sensor which is dipped in the liquid in the second tank senses a liquid height in the tank in terms of capacitance. The output of the height sensor is representative of a viscosity of the liquid.

Abstract: An ink ejection head including a nozzle holding member having an ink ejection nozzle threadably connected to a forward end portion of a liquid chamber structure. The ink ejection heads further includes a sealing member, such as a packing or an O-ring, located inwardly of a threaded connection as viewed from a liquid chamber in the liquid chamber structure. Introduction of dust or grit through the threaded connection into the liquid chamber can be effectively avoided by this arrangement, to thereby prevent obturation of the ink ejection nozzle.