Ing C. Olivetti C., S.p.a.

Alessandro Crotti

Roberto Realis Luc

Pierangelo Berruti

Roberto Guelfo

Daniele Mazzini

Ennio A Pozzo

Roberto R Luc

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.

Electronic typewriter

In an ink jet printing element in which the drop is expelled by generating a current pulse through the ink in the nozzle, in order to reduce the control voltage, a first pulse (Tr) for heating the ink is generated, followed by a vaporization pulse (Tv) with a delay such as to make the printing position independent of the direction of movement of the element with respect to the paper. The heating pulse (Tr) is generated by a circuit (31) controlled by a temperature sensor (34) so that the duration of the heating pulse has a negative temperature coefficient. The vaporization pulse (Tv) is generated by a circuit (32) manually controlled (potentiometer 39) to determine the pulse duration on the basis of the desired strength of the printing. The delay between the two pulses is controlled by a delay circuit (38), e.g. a monostable circuit. The two pulses are applied to a transformer (35) which generates the voltage between the electrodes. The two circuits (31, 32) may be constituted by one monostable circuit with separate RC networks sequentially enabled for determining the durations of the heating and vaporization pulses.

Control apparatus for an on-demand ink jet printing element

The head is formed by a container (2) comprising a rigid frame (14, 16) of tapered shape, bearing the nozzle (4) at one end thereof. Fitted into the frame is a tubular membrane (47) for containing the ink, which is sealed at the other end of the frame by a metal plate (51) connected to an electrode (6) in contact with the ink. The frame is provided with openings (58) to permit the membrane to keep the ink at atmospheric pressure. The electrode (6) is formed by a blade spring in contact with the metal plate (51) and is provided with a projection (42) disposed in a chamber (30) in the vicinity of the nozzle to maintain contact with the ink right up to exhaustion of the cartridge. The head is removably fixed in a seat on a carriage by means of lever which urges the head into its seat and also serves as electrical contact with the metal plate. A second contact is made to an electrode on the front of an alumina plate (3 ) in which the nozzle (4) is formed.

Ink jet print head and printer

The head (12) comprises a closed container (14) carrying two electrodes (36, 62) and a nozzle (18) and mounted removably on a carriage (13). In order for the ink (16) always to be held at atmospheric pressure, the container (14) comprises an expansible space defined by a diaphragm (67) having a portion (74) aligned with an opening (73) in the container (14). The diaphragm (67) is of butyl rubber which can be pierced with a syringe to permit the container (14) to be refilled with ink (18). The container (14) is closed by an alumina plate (32) carrying the nozzle (18) and joined to a second plate (76) parallel thereto, and of a material which can be wetted by the ink (16). The second plate (76) constitutes a wall for resisting the pressure waves of an ink jet leaving the nozzle (18), and is immediately covered by the ink again.

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Strambino, Italy

Alessandro Crotti