Abstract: A mechanically balanced pulsed ink droplet mechanism includes a disk or ring of piezoelectric ceramic material positioned within a metal ring of rectangular cross section having an annular channel in its inner surface that is sealed by a thin metal diaphragm to form an annular ink chamber. The piezoelectric transducer is in mechanical engagement with the inner surface of the annular diaphragm, but the ink is electrically insulated from the ceramic. A voltage pulse applied to opposite sides of the disk causes it to expand and eject a droplet of ink from the printing orifice.The ink chamber is shallow and has a ratio of cross section to wetted perimeter or hydraulic radius approximately equal to the diameter of the orifice which quickly damps oscillations resulting from the ejection of each droplet of ink and permitting higher speed operation. The ink chamber is sealed without the use of compliant materials resulting in minimal additional compliance to the liquid.

Abstract: The method of making a print head of the type that includes a piezoelectric transducer positioned within a metal housing having an annular channel in its inner surface that is sealed by a thin metal diaphragm to form an annular ink chamber. The transducer is in mechanical engagement with the inner surface of the diaphragm. The sudden removal of a voltage applied to the transducer expands the disk to reduce the volume of the ink chamber, rupture the meniscus, and force a droplet of ink from the printing orifice.The housing is formed with an internal taper which permits a groove to be cut readily either by a casting or by a tool entering from the larger end of the central opening in the housing. An aluminum mandrel is tapered to match the taper on the inner surface of the housing and provided with an annular groove that corresponds to the groove in the housing. The mandrel is plated with nickel that will later form the diaphragm. The housing and mandrel are then plated with indium.

Abstract: A pen recorder driving mechanism for deflecting a recorder pen on a writing medium in response to electrical input signals is disclosed. The improved pen recorder driving mechanism includes a novel laminar coil assembly rotatably mounted in a precision air gap between a permanent inner core magnet and a highly permeable outer shell. The coil assembly comprises a coil frame having an inner frame around which the windings of a driving coil are wound and an outer frame overlayered on the windings and the inner frame. The coil frame laminations are rigidified by a bonding material applied to the windings during their assembly. The coil frame is subsequently shaped into a generally rectangular concave convex configuration by stretching the laminations during manufacture with a forming tool. Half shafts and end pieces are attached to the transverse legs of the coil frame after shaping to define the rotational axis of the coil assembly and to provide a mounting structure.