Abstract: The method for driving a stepping motor for printers comprises the generation of first pulses (16A,16B) at n levels recorded in registers and representing a simulation of sinusoidal waves. The maximum level is applied during two consecutive microsteps to one of the phases of the motor, while the level of the other phase changes sign. During a motor stopping command, second pulses (VCA,VCB) are applied to the registers and to the two phases of the motor and are programmed so as to ensure, during the last microstep, an exact stopping position, such that all the stopping positions are kept apart by a whole number of half steps. Very precise, fast and noise-free printing is thus attained. The resolution is doubled, without any loss of precision or speed.

Abstract: The printer comprises an entrance, a printing station, a collection tray for the printed sheets and temporary storage mechanisms on which a printed sheet is placed immediately after printing. These mechanisms comprise pivotingly mounted shutters, opening and closing of which is commanded by a slide comprising two rails cooperating with levers integral with the shafts of the shutters. The slide can be made temporarily integral with the printing carriage by means of a selection pin, the cams of which cooperate with two fixed abutments. The carriage thus performs selection and driving of the temporary storage mechanisms, which are easy to build and operate precisely at a low cost price.

Abstract: An ink jet printhead comprising a plurality of ejection resistors and at least one additional resistor, integrated on the same semiconductor substrate; the additional resistor is constituted by a material with a positive coefficient of variation of resistance with temperature of between 0.3 and 1.0%/.degree.C. and is used both for heating of the substrate and for measuring its temperature. Various circuits based on using the additional resistor are defined for implementing a method for stabilizing temperature of the substrate; also defined are a method for obtaining a stabilization temperature that remains constant with variation of the characteristics of the head and a method for setting the energetic operating point of the ejection resistors.

Abstract: In a station for cleaning, restoring and protecting the nozzles of an ink jet printer, a cleaning blade is connected to the nozzle restoring and protecting device and controlled by it when moved by the motion of the print head into its operating position. The restoring and protecting device comprises two covers that are selectively coupled to one or the other of two heads for printing in black or in color, respectively. The restoring and protecting device sets the cleaning blade in the best position for cleaning the two heads, by means of a rocker. The service station is of a simple construction and uses a small number of component parts.

Abstract: In an ink-jet printing unit comprising a printing head mounted on the container, a measuring circuit comprising a pair of electrodes which substantially enclose the volume of ink within the container, allows hysteresis- free linear mode measurement of variations in the ink volume within the container and the signalling of at least one of the ends of the variation interval to indicate the most suitable moment for recharging ink in the container by means of a cartridge inserted into the container.

Abstract: This invention concerns an ink composition for thermal ink-jet printing consisting of an aqueous solution, a co-solvent, a dye, a pH regulator, a viscosity modifier, a biocide and a mixture of three non-ionic surface-active agents, one of which is diethylene glycol mono-hexyl ether and the other two are fatty ethoxylate alcohols. This ink composition allows drying times to be reduced to under 2 seconds, gives the printing high water resistance and permits use of the papers known as "recycled" with very good quality printing results, without in any way impairing storage capability, operation and endurance of the printhead.

Abstract: In an electrostatic image developing device for electrical photocopiers, a magnetizable one-component toner, initially contained in a removable container, is fed, by the action of a rotating flexible strip, through a development chamber towards a rotating non-magnetic development roller surrounding a number of stationary permanent magnets, forming on it a magnetic brush, whose thickness is controlled by a non-magnetic flexible blade pressed against the surface of the development roller; the development chamber is fitted with three stirring bars made of non-magnetic material, each bar describing a different closed path in different zones of the development chamber in such a way as to avoid the formation of lumps and to maintain the correct fluidity of the toner. In addition, a metallic wire is fitted in the development chamber and acts as a sensor device to detect when the removable container is nearly empty of toner.

Abstract: A thermal ink jet printing module, of the type that can be removably mounted on the carriage of a printer, comprises a reservoir for the ink and a thermal ink jet printing head fixed to and communicating with the reservoir, and a housing integral with the reservoir for receiving an ink refill cartridge for supplying the spent module with fresh ink by means of a transfer element integral with the housing of the cartridge. Successive refilling of the printing module exploits the working life of the head to the utmost and reduces the waste of expensive materials. The reservoir can be refilled relatively easily, even when the user is travelling.

Abstract: The present invention relates to a cleaning device for a fixing unit used, for example in an electric photocopier, for fixing a developed image on a support. The fixing unit is formed by a fuser assembly, in contact with which there moves a film that is rolled up to form an endless belt. The film is set in motion by a drive roller which transmits a drive torque to the belt. The cleaning device removes contaminating particles from the external surface of the drive roller in order to keep constant the coefficient of friction as between the film and the drive roller.

Abstract: A paper tray for a photocopier comprises a container (1) which can travel between open (E) and closed (L) positions. It moves along guides (22, 24). A drive mechanism (32) move the container from the closed to the open position by exerting a constant force on the container. The container is mounted on a carriage (20). This is supported by a pair of transport rollers (28) which roll along the guides. The rollers (28) are firmly connected together for rotation by a shaft (30).A locking mechanism is provided for the container. A lever (54) is rotatable on the photocopier to lock the container in the closed position. The lever is coupled to a slide (60) having a cam groove (65) therein. This is arranged to move a locking element (55) which engages the lever (54) so as to release the lever (54) as the container is pushed further into the photocopier in the closed position.

Abstract: Improvements relate to a photocopying machine with an auxiliary sheet feeder including a sheet-separation unit which withdraws sheets disposed on a tray. The improvements enable better separation of the sheets and easier removal of jammed sheets. (FIG. 1).

Abstract: A ventilation device for a photocopier draws ozone mixed air from a developing unit and image transfer unit and forwards it to ventilate a fusion unit where the subsequent heating of the air reduces the ozone content. The air flow evacuates the condensed water issued by the sheets of paper during the fixing.

Abstract: Fixing device for copying machines in which a linear heating element, positioned transversely to the movement of the sheet of paper, is immediately followed by a shoulder projecting beyond the heating element towards a pressure roll in order to give the paper an opposite curl to that spontaneously adopted. The sheets of paper emerge from the fixing device having retained their flat form. Because of the high specific pressure on the shoulder fixing is improved.

Abstract: In photocopying and/or printing machines, the blower or fan used for internal ventilation is suspended from the structure of the machine by springs slung between the blower casing and the machine structure to eliminate the transmission of vibrations to delicate members in the machine itself.

Abstract: A device for blocking or intercepting sheets for a sheet feeder may be applied to copiers, printers and similar office machines, and comprises a lever (32) capable of detecting the presence or absence of a sheet on the sheet entry hopper (16). The lever controls a stop member (42) to prevent the introduction of further sheets when at least one sheet is still present in a hopper.

Abstract: An image is fixed to a sheet of paper, in an image reproducing machine in a fixing station (GF). This uses heat and pressure to fix the image. A pair of straightening rolls (24, 26) downstream of the fixing station apply tension to the sheets in the direction of advance and forward them in a direction which inclines by a predetermined angle of correction with respect to the direction (21) with which the sheets leave the fixing station. The straightening rolls form a nip (62) therebetween and this may extend around a portion of the periphery of one of the rolls such that sheets passing therethrough are bent in an opposite direction to their natural direction of curl.

Abstract: The device for the introduction of sheets makes it possible to introduce a stack of sheets through an auxiliary input or by-pass in addition to or as an alternative to the normal cassettes for sheets, with which the machine is fitted. A roll (57) rotating on a shaft (58) separates sheets from a stack inserted into a tray (54). A lever (68) is movable from a rest position to a function position. When the lever is moved to the functional position it causes a unidirectional clutch (86) mounted on the shaft to reverse the direction of rotation of the roll thereby moving sheets back to the tray. The lever also moves a cam (76) such that when the lever moved to the functional position, the tray is moved away from the roll such that additional sheets can be inserted.