Abstract: In an electrophotographic printing device, a charging roller for a photoconductive drum is constituted by an outer, resilient and resistive layer and by a conductive core connected to earth by means of an element with adjustable resistance. The charging roller is rotated and at the same time its outer layer is charged, by an auxiliary conductive roller which is in contact with the charging roller along a generatrix, with a specific surface charge which is discharged gradually through the resistive layer and the adjustable resistor according to a law determined by the value of the adjustable resistor so that the residual charge transferred by the charging roller to the drum can be controlled simply, reliably and repetitively, so as to adopt an optimal value.

Abstract: An electrophotographic apparatus incorporating a sorter device formed by a double pair of driving rollers for ejecting sheets from the apparatus and delivering them into a collecting bin, the two roller pairs acting on the side edges of the sheets at selectively controllable velocities to selectively produce an angular deflection of the outgoing sheets in either of two directions and their delivery into the collecting bin in different positions rotated from each other, the bin having an opening dihedral with side walls which define the maximum amounts of imparted deflection for the two positions.

Abstract: Electrophotographic developing apparatus including a carrier of latent image formed on a photoconductive layer superposed to a conductive layer, a carrier of developing material juxtaposed to the latent image carrier at a developing zone for transferring the developing material on the photoconductive layer in a configuration corresponding to the latent image and a transfer station in which a printing support is brought in contact with the photoconductive layer for transferring the developing material from the photoconductive layer to the printing support, the distribution of the developing material on the photoconductive layer being enhanced by subjecting the photoconductive layer, in a zone extending between the developing zone and the transfer station, to an alternating electrical field which enables migration of developing material particles from the outside of the latent image to the inside of the latent image.

Abstract: Apparatus for automatically adjusting the distance of a printing head from a printing support wherein motor means enable changing, on command, the print head distance from the support and a movable armature/plunger electromagnetic detector, fixed to the printing head is energized, when the print head is moved far from the printing support, so as to perform the cocking of the armature/plunger and is thereafter maintained in energized status by a minimal current for holding the electromagnet in cocked state, so that a subsequent movement of the print head towards the printing support, owing to the interference with the printing support of an actuation element coupled to the armature/plunger, causes armature/plunger release and a reluctance change, hence an e.m.f. induced in the energization winding which is detected by a comparator circuit and signaled to a control logic to indicate that the print head is at a predetermined distance from the printing support.

Abstract: An automatic paper bail actuator for a printer having a rotating platen or equivalent means for feeding a printing support including a helicoidal spring wound on the platen shaft and having two end arms, a first arm being elongated to interfere with the bail and a first reference stop, the spring coil being clamped on the shaft by interference with the bail and opening the bail when the shaft rotates in the direction opposite to the one providing normal forward feeding of a printing support, closing the bail when the shaft rotates in the direction providing normal forward feeding until the first arm interferes with the first reference stop and releases the spring coils; the second arm interfering with a second reference stop for a rotation of the shaft in the direction opposite to the normal one and releasing the spring coils for a predetermined angular position of the spring and the first arm, hence for a predetermined open position of the bail.

Abstract: Aerodynamic damper for impact printing actuator in which a movable armature of a magnetic circuit has to resume, after actuation, with minimum rebounding and oscillations, a stable rest position defined by the contact of a flat surface of the armature with a flat surface of a stop element, consisting in a recess formed of at least one of the two flat surfaces and having peripheral side walls slanted as to the flat surface.

Abstract: Belt tensioning apparatus for a serial printer wherein a spring imparts a predetermined pull to driving belt by applying a predetermined force to a slide on which a belt return idle pulley is mounted, and wherein a slide is offset from a working point and in the direction opposite to the force exerted by the spring by an amount controlled by a stop pad, preferably resilient and position adjustable, or automatically changeable in position owing to belt elongations occurring during operation.

Abstract: A stepping motor drive circuit having pairs of magnetically coupled phase windings (1, 3 and 2, 4), comprises current chopping control circuits (23, 24) for controlling the on/off switching of a plurality of driving transistors (5, 6, 7, 8) each coupled to a respective phase winding, and the circuits associated with each switching transistor for reducing their storage times and hence switching losses. More particularly, with reference to the switching transistor (5), the related circuit for storage time reduction comprises a series connected capacitor (25) and a diode (45). The circuit connects between one terminal of one winding (2) of the pair of phase windings which is magnetically coupled to the one winding (1) of the other pair connected to such switching transistor (5) and to the base of such transistor (5). As soon as the transistor (5) is caused to switch from ON to OFF, the circuit applies a reverse voltage pulse to the base of the transistor (5) causing a fast transition towards the cutoff region.

Abstract: In a tape transport of the type where tape traveling between a pair of tape reels is selectively moved past a recording/readout station by externally controlled capstan means, a novel, semiautomatic system is provided for loading the tape into the transport. In accordance with the present invention, this is accomplished by manual insertion of the tape into a first tape path and by subsequent, stepwise automatic loading into a second tape path when predetermined operating conditions in the transport are present. Transport disabling means, normally operative in the absence of the aforesaid operating conditions, are inhibited during the tape loading operation, becoming operative again when the transport is fully loaded and ready for normal operation. Apparatus for loading tape in this manner avoids the time delays and reliability problems of fully manual loading systems, as well as the high cost and lack of reliability in certain critical areas of fully automatic tape loading equipment.