Abstract: An ink jet printing head, particularly intended for printing large characters, includes at least two modulation bodies having respective nozzles fitted with a device for adjusting each of the jets generated by the nozzles. A single module for recovering the ink with only one return line is incorporated in the head. The casing of the head receives, on its face, a support for a cover and, optionally, a second umbilical cover. For printing bar codes, the head provides a cascade sequencing of printed rasters with an increasing order of sequencing of droplets due to a charge voltage. The head is oriented to compensate for the inclination of the raster on the support.

Abstract: The invention provides a method for checking the printing quality of an ink jet printer. A control frame is printed independently of a marking message. This frame is, for example, formed of 15 dots of which the charge increases from the first to the fifteenth droplet. The distance (G.sub.1, G.sub.2, G.sub.3) separating, respectively, the droplets (1) and (8), the droplets (8) and (15) and the droplets (1) and (15) are permanently maintained so as to correspond to the two relationships: G.sub.1 G.sub.3 =k.sub.1 and G.sub.2 /G.sub.2 =k.sub.2, where k.sub.1 and k.sub.2 are constants.

Abstract: A device is provided for receiving a combination of two variable volume chambers and a plurality of valves for forming an ink supply circuit for an ink jet printing head. Such a device is formed by a solid one-piece block comprising a plurality of cavities which are disposed radially about a central housing receiving both a piston (P) and a pressure sensor (5). The piston (P) being formed by the stacking of at least two pieces of diameter O.sub.1 and O.sub.2 and two membranes clamped by two flanges, the whole defining two variable volume chambers. This device cooperates with a reservoir block having two compartments between which moves a link connected on one side to an eccentric and on the other to the piston for forming an extremely reliable and compact ink supply circuit.

Abstract: The invention provides a cell having a variable volume chamber and a fluid supply circuit for an ink jet printing head which is equipped therewith. The cell includes a variable volume chamber (1) connected to a pressure sensor (5) and to at least a pair of valves (7, 9) each associated with a restriction (8, 10). The variation of volume is obtained by means of a piston actuated by an eccentric (3) secured to the rotor of a stepping motor (4). The maximum pressure difference generated at the ends of the restrictions (8, 10) is used to measure the viscosity of the fluid which flows through the corresponding valves (7, 9).

Abstract: Disclosed is a cell having a variable volume chamber and a fluid supply circuit for an ink jet printing head which is equipped therewith, the cell including a variable volume chamber (1) connected to a pressure sensor (5) and to at least a pair of valves (7, 9) each associated with a restriction (8, 10); the variation of volume being obtained by a piston actuated by an eccentric (3) secured to the rotor of a motor (4).

Abstract: Ink jet printing head and replacement of bevel sticks in industrial tracers by an ink jet printing head provided with a set of deflection plates (3, 4, 5) so arranged and polarized that the electric field of deflection of droplets is orientable according to an angle which may vary from 0.degree. to 180.degree.. The applications cover particularly the field of industrial tracing techniques.

Abstract: In a ink jet printing head, all essential elements are made integral with a monolithic part (2) acting as a base. Furthermore, the modulation body (10) cooperates with adjusting means (screw 84 and oblong holes 85) according to two angles (.alpha.) and (.beta.), situated in two perpendicular planes. The charge (71), charge-control (72l ) and deflexion (73, 74) electrodes are integral with a block (70). The electric isolation is provided particularly by means of a groove (89) and a web (90), thereby preventing any arc formation. The inventon can be applied to any ink jet printer.

Abstract: The invention relates to a circuit for feeding ink to an ink-jet printing head.Consideration is given to a circuit comprising in particular a first auxiliary circuit (R1), the function of which is to measure the ink pressure between the feed pipe (20) and the ink supply pipe (18) and a second auxiliary circuit R2 which serves if necessary to clear the orifice (41) for discharging ink drops (100).This circuit can also comprise a third auxiliary circuit R3 for delivering a signal which is representative of the viscosity of the ink.Measurement of the pressure and of the viscosity permits control of the principal parameters governing the operation of the printer which is equipped with the circuit.The invention applies to any ink-jet printer.

Abstract: A charge detector forming part of a device for controlling the electrostatic charge applied to ink drops in an ink-jet printer comprises at least one internal conductive cylindrical rod connected to an electronic circuit and surrounded by an insulating sleeve. The sleeve is tightly fitted within an outer conductive cylinder which is connected to ground. A calibrated slot of predetermined length and width is formed so as to provide a passageway for the flow of ink drops through the detector. As each ink drop passes in front of the conductive cylindrical rod, a signal is induced and processed by the electronic circuit. The device also serves to control at least one ink-pressurizing pump with a view to ensuring constant flow velocity of the ink drops.

Abstract: A safety device for the conductive-fluid circulation system of an ink-jet printer consists of a sensor and an associated electronic circuit inserted between an ink-drop recovery trough and a recirculating pump. The level of turbulence of the fluid flow within a pipe segment of insulating material located between two conductive pipe segments is determined by the sensor by measuring the variation in conductivity in relation to variations in cross-sectional area of fluid within the insulating pipe segment and by delivering a control logic signal.

Abstract: A reading head scans a document to be reproduced line by line and delivers an analog signal the amplitude variations of which represent the variations in tint on the document. An analog-digital converter preceded by a sampler for sampling the analog signal delivers, in respect of each line scanned, n digital samples (where n is a positive integer) corresponding to the tints to be reproduced on a line of a sheet of thermosensitive paper. For each line to be reproduced, a set of storage shift registers generates n control signals which are functions of the digital values of the n samples associated to the tints to be reproduced. These signals control power supply means for feeding n resistors on a thermal printing head.