Abstract: A method for making an etched base plate for an ink printer head includes the steps of disposing on each face of a base plate a mask having a pattern, exposing the base plate simultaneously through the masks to light of a wavelength to which the base plate is photosenstive, heating the base plate to a temperature at which the amorphous glass structure in the exposed regions is converted to a ceramic crystalline structure and dipping the base plate into an etching agent solution to remove the crystalline structure from the base plate to thus provide in each plate face ink printing chambers, ink channels and at least one row of nozzle discharge openings in the shape of the exposed regions. The patterns formed on the masks are mirror images of each other.

Abstract: A method of providing an ink jet printing head with piezo-crystals comprises the steps of providing a plateshaped basic printing head body including an ink supply reservoir, ink pressure chambers, ink exit openings, ink outlet channels which connect the pressure chambers with the ink exit openings, and ink inlet channels for connecting the pressure chambers with the ink supply chamber; providing a membrane plate; providing an piezo-ceramic plate; attaching the piezo-ceramic plate face-to-face to the membrane plate; attaching the membrane plate face-to-face to the basic body; and subsequent to attaching the piezo-ceramic plate to the membrane plate, entirely separating piezo-crystals from the piezo-ceramic plate by providing closed-course cuts through the piezo-ceramic plate such that a separate piezo-crystal is obtained in alignment with each pressure chamber.

Abstract: In a key-operated machine in which actuation of a key moves code elements of an associated code card into the path of a photoelectric sensing system, each code card is moved by a drive mechanism so as to cause the code elements to traverse the sensing system path only once, and at a speed which is independent of the speed of key movement, in response to each key actuation.