Abstract: A pressurizing chamber 1 is formed as a recess by half etching of a silicon single-crystal substrate 2. A nozzle communicating hole 6 through which the pressurizing chamber 1 is connected to a nozzle opening 5 is formed as a through hole which is smaller in width than the pressurizing chamber 1. The pressurizing chamber 1 is connected to the nozzle opening 5 in the other face via the nozzle communicating hole 6 while reducing the volume of the pressurizing chamber 1 to a degree as small as possible. The silicon single-crystal substrate is used as a member constituting a spacer so that an ink drop of a reduced ink amount suitable for high density printing flies with high positioning accuracy.

Abstract: An apparatus for printing directly on plain paper, utilizing an arrayed control grid having a plurality of toner slots disposed in a space between a toner carrier and a backing electrode on which a paper travels. The backing electrode formed in a flat plate facing paralleledly to the control grid assures a uniform electrostatic field in an interspace therebetween. A unit body associated with the toner carrier and the control grid makes the interspace open when the unit body is removed from the apparatus body which offers an easy access to the interspace and the members as well. A resiliently suspended backing electrode with a spacer, a restriction member etc., assures the interspace constant. Other unit bodies including the control grid associated with the backing electrode and others are also disclosed.