Abstract:
An electronic typewriter (11) has a line spacing device (29) for rotating a platen roller (16) and a transport device (28) for moving a printing carriage (19) in both directions. The line spacing and transport devices are driven from a single motor (32) via an intermediate gear (40) mounted on a shift member (35). The shift member (35) is displaceable between two operative positions for connecting a driveshaft (33) to the transport device (28) or to the line spacing device (29). A servomechanism (36) which is motorized by the shaft (33) displaces the shift member (35) between the two positions by means of a shift electromagnet (81) which actuates a lever (79) to lock the gear (40) by means of teeth (88) on a slide member (43). Positioning means (44) hold the shift member (35) in each of the two operative positions, and an electronic control means (22) controls the motor (32 ) and the electromagnet (81). The system is of low cost, and is simple, functional and reliable.
Abstract:
A feed arrangement for a typing ribbon and/or a correction ribbon comprises a linear motor having a coil-carrying slide which is movable with an alternating rectilinear movement, a toothed wheel for the feed movement of the ribbon, and a connecting mechanism interposed between the coil-carrying slide and the wheel for converting the movement of the slide into a unidirectional rotary movement of the wheel for advancing the ribbon. The connecting mechanism comprises a first lever which is moved by the slide and two mutually independent ratchet assemblies and which are capable of alternately engaging with two diametrally oppositely disposed teeth on the toothed wheel. The ribbon is carried by a cassette and the wheel rotates a blade capable of engaging into a seat in a feed roller of the cassette.The linear motor is of the type comprising a permanent magnet of cylindrical shape, a ferromagnetic core which is coaxial with respect to the magnet and which surrounds the permanent magnet and defines a radial air gap with the permanent magnet, and a winding which is accommodated in the air gap and is supported by the coil-carrying slide. The slide is capable of bidirectional movement coaxially with respect to the permanent magnet in response to bidirectional excitation currents in the winding, coming from an actuation circuit which in turn is controlled by a central unit of the machine.
Abstract:
In a thermal ink jet print head the ink is expelled in the form of small drops through a plurality of nozzles communicating with corresponding expulsion chambers for expulsion of the ink through the effect of rapid heating of heater elements contained in the expulsion chambers. The nozzles, the expulsion chambers, the heater elements and the associated electrical conductors are constructed in a plurality of metal layers and insulating layers supported by a silicon plate. The plate is fixed to the structure of the head and is supplied with ink contained in a movable cartridge fitted to the structure of the head. The cartridge comprises a rigid reservoir containing a sponge saturated with ink which can be hydraulically connected to the head by means of a needle-type conduit mounted on the head and which perforates a rubber membrane of the cartridge. During the periods of storage and inactivity of the head, the cartridge is removed, permitting drying of the nozzles to avoid possible nozzle blockages and corrosion of the layers of the plate by the ink.
Abstract:
A cassette for a printing ribbon for typewriters comprises a casing accommodating a supply spool, a receiving spool and a brake and take up device which operates on a tube of the supply spool and on the ribbon which is unwound from the supply spool. The tube is rotatable on a sleeve projecting from the bottom of the casing. The brake and take up device comprises a shoe for applying a braking action to an internal surface of the tube. A wire spring has an intermediate portion which engages in a seat of coupling means of the shoe. In a first position the shoe is urged against the surface of the tube and brakes the supply spool. In a second position the shoe is spaced from the internal surface of the tube and the supply spool is free to rotate. The spring also performs the slack ribbon take-up function and for that purpose comprises an end having an L-shaped bent portion which in turn is engaged with the ribbon to regulate the tension and unwinding of the ribbon which is unwound from the supply spool.
Abstract:
The contact-type keyboard comprises a plurality of keys which are movable from a rest position to an operative position and which each have a sleeve capable of being accommodated in a tube provided on the upper part of a dome portion of elastomeric material. Each dome portion projects from a mat and, below the tube, comprises an internal circular ring provided with a movable conductive portion for short-circuiting a corresponding fixed conductor of a printed circuit which in turn is carried by a stop plate of insulating material. Each sleeve is of such a length as to pass internally by way of an upper opening through the dome portion, to engage a through hole in the plate to project downwardly beyond the plate and comprises a seat capable of accommodating a corresponding pin of a support frame structure so as to guide the respective key from the rest position to the operative position and vice-versa. The support frame structure is positioned below the stop plate at a predetermined spacing such that it does not interfere with the end of the sleeve when the respective key is in the operative position. The key is in turn restrained to the plate by means of a lateral appendix which is freely accommodated by a seat in the plate and provided with a hook portion which is retained by the plate.
Abstract:
Each needle of the printer has an associated electromagnet with a generally elongate movable armature having a first end and a second end which can selectively push the needle during printing as a result of a pivoting movement within a step formation facing the electromagnet. The step formation divides the armature into first and second portions facing the first and second ends respectively, and faces the respective electromagnet in such a position that the second portion of the armature at least partially faces the electromagnet.
Abstract:
The print apparatus comprises a character-carrying element of the `daisywheel` type with flexible spokes which can be selectively positioned in front of a platen roller, a print hammer for moving a selected character towards the platen roller, an actuating solenoid for the print hammer and a damping mechanism which acts on the hammer after the printing of each character. The hammer is directly connected to a movable armature of the solenoid and is returned by a return spring.During the return phase, the armature displaces, against a travel limiting stop, a counteracting weight which is urged towards an intermediate stop by the force of a counteracting spring. A first damping element is disposed between the movable armature and the counteracting weight and a second damping element is disposed between the weight and the travel limiting stop. The two damping elements, operating sequentially, minimize the time required for the hammer to settle down.
Abstract:
The logic signals (S0, S1, S2, HL) which define the pixel are combined together with the synchronization signals (HS, VS) by a composer circuit (19) disposed in the display control, to form a single composite signal. The composer circuit (19) is connected by way of a single conductor (21) to a separator circuit (29) for separating the synchronizing signal, disposed in the VDU control circuit (20). The VDU control circuit comprises horizontal and vertical deflection circuits (27, 43 and 28, 44) for a CRT (24) and further comprises a format selector circuit (30) which is capable of sensing the duration of the vertical synchronizing pulse to control the frequency of the video signal vertical deflection circuit (28, 44).