Abstract: A printing device for printing on a supplied paper, said printing device being provided therein with ink ejecting elements for ejecting ink from ink flow paths having nozzles on its front end and formed in ink jet head, and with a controlling means for electrically controlling said ink ejecting elements, said printing device being characterized in that said controlling means is constructed such that electric controlling conditions with respect to said ink ejecting elements are varied according to types of ink used. By such a construction, it becomes possible to drive ejecting elements in an excellent driving conditions adapted to type of ink used, thereby to deliver ink onto paper in a stable manner for carrying out a good quality of printing.

Abstract: A printing device for printing on a supplied paper, said printing device being provided therein with ink ejecting elements for ejecting ink from ink flow paths having nozzles on its front end and formed in ink jet head, and with a controlling means for electrically controlling said ink ejecting elements, said printing device being characterized in that said controlling means is constructed such that electric controlling conditions with respect to said ink ejecting elements are varied according to types of ink used. By such a construction, it becomes possible to drive ejecting elements in an excellent driving conditions adapted to type of ink used, thereby to deliver ink onto paper in a stable manner for carrying out a good quality of printing.

Abstract: An ink jet head which enables using plural types of ink in the head to accommodate varying types of paper or objects to be imprinted. The single ink jet head includes plural cartridges which are selected in accordance with the property of the medium which is imprinted or the ink finish which is desired. The ink jet head includes a discharge element which is excitable under a controller to comply with the characteristics of the type of ink sensed by detecting the electrical conductivity of the ink.

Abstract: An air-bubble detection apparatus which detects the presence or absence of the occurrence of air bubbles in an ink passage by detecting if the voltage which develops across an electrostrictive vibrator by mechanical strain as a result of the ink in the ink passage of an ink jet recording head being moved, exceeds an excess voltage above a drive voltage. In addition, a method and apparatus for restoring the recording head to its operating condition, which prevents ink and energy from being wasted and makes efficient printing possible by restoring the recording head in which the occurrence of air bubbles is detected by using the above air-bubble detection apparatus.

Abstract: An ink jet head used in an ink jet printer, having a flat nozzle block, and a main tank member which is connected to a base end of the nozzle block and in which is formed a main ink tank for storing ink supplied to ink flow passages formed in the nozzle block. An auxiliary tank member in which an auxiliary tank is formed is connected to the main tank member. A slant surface downwardly inclined from an upstream position to a downstream position with respect to the direction of ink supply is formed as a part of the upper internal wall of the ink tank. Supplied ink collides against this slant surface so that air in the ink separates from the ink.