Abstract: The invention relates to a multi-channel RF-excited gas laser device which has an elongate tubular dielectric housing 1. The housing has a common elongate ground electrode 2 therein and a plurality of laser channels 4 defined within and extending along the ground electrode 2 adjacent to an interior surface 3 of the dielectric housing. A laser gas is provided within the dielectric housing and a plurality of RF electrodes 7 are disposed adjacent to and extending along an external surface 8 of the dielectric housing 1. Each RF electrode 7 is disposed in registration with one of the laser channels 4.

Abstract: A print head for a continuous ink jet printer has a nozzle 5 through which ink is emitted and broken up into droplets under the action of a piezoelectric oscillator. A charge electrode 3 applies charge to selected droplets and a deflection electrode 4 deflects the path 20 of the charged droplets to cause printing on a substrate. A gutter 6 collects droplets which are not required for printing. A charge electrode 3, together with one of the deflection electrodes 4 is movable in a direction transverse to the path of the droplets selectively under the action of pressurised ink fed from an ink supply 14. Similarly, the gutter 6 is movable in the same way.

Abstract: A pump (1) has a rotor (4) and a stator (3) disposed closely adjacent to and biased towards it, but spaced apart from a surface of the rotor. The stator (3) or rotor (4) has recesses (30) on its surface facing the rotor or stator respectively, and an inlet to and an outlet from each recess to provide for the supply of fluid to and from the recess. Rotation of the rotor (4) about its axis is arranged to cause fluid to be pumped from the inlet to the outlet as a result of the viscous drag on the fluid resulting from rotation of the rotor relative to the stator (3). The force biasing the rotor (4) and stator (3) together is provided at least in part by fluid pressure feedback from the pump (1) in order to control the clamping or biasing pressure between the rotor and stator automatically.

Abstract: A printhead (1) for an ink jet printer includes a chamber (5) for containing marking fluid fed to the head in use. A plurality of orifices (8) open from the chamber (5), a marking fluid being emitted in use through the orifices (8). A corresponding plurality of actuators are provided. Each actuator comprises an arm (12) having at one end means for selectively opening and closing a respective orifice (8); a magnetic circuit (12, 13, 14, 15) of which the arm (12) forms a side; and one or more coils (14) for selectively inducing a magnetic flux in the circuit in order to move the arm (12) between a position in which it closes the respective orifice (8) and a position in which it opens the orifice (8).

Abstract: A galvanometer optics assembly includes a housing which has a laser beam input which is optically coupled to the laser beam output of the laser marking apparatus, a first laser beam output and a second laser beam output, a stationary mirror which is fixedly coupled to the housing and is optically coupled to the laser beam input of the housing, a galvanometer mirror which is rotatively coupled to the housing and is optically coupled to the stationary mirror, a galvanometer optics motor which has a shaft which is fixedly coupled to the galvanometer mirror so that the galvanometer mirror may be optically coupled to either the first laser beam output or the second laser beam output and a galvanometer controller which is electrically coupled to the galvanometer optics motor. The galvanometer optics assembly is for use with a laser marking apparatus which includes a housing and and a laser beam output which is optically coupled to the lasers.

Abstract: Ink jet inks are disclosed comprising a liquid vehicle which is preferably a blend of ethanol and water in a weight ratio of 23/70 (equivalent to 30/70 by volume) to 71/10 (equivalent to 90/10 by volume), a binder, which comprises a sugar or a sugar alcohol or a mixture thereof, preferably a mixture of sorbitol and maltitol, which is soluble in the liquid vehicle, a colorant which is soluble in the liquid vehicle and a surfactant comprising 90% or more of phosphatidylcholine or lysophosphatidylcholine, which is soluble in the liquid vehicle.

Abstract: A continuous ink jet printer has a nozzle plate 1 which includes an orifice 3 for emitting a stream of ink. A counterbore 4 surrounds the orifice. A passage 5, 6 is provided which lies substantially in the plane of the plate and intersects the counterbore, and through which a flow of cleaning agent may be supplied to the counterbore, in order to flush ink from the surrounds of the orifice.

Abstract: There is provided an ink jet ink comprising a binder, a colourant, a liquid vehicle and an adhesion promoter, the adhesion promoter being an alkoxysilane polyalkylene-imine containing repeat units of the formula (I): ##STR1## wherein R.sup.5 represents a bond to another nitrogen atom and R.sup.4 represents a bond to another carbon atom or a hydrogen atom; a is from 1 to 8; b is 1 to 8; c is from 1 to 6; at least one of R.sup.1, R.sup.2 and R.sup.3 is a C.sub.1 -C.sub.6 alkoxy group and any of R.sup.1, R.sup.2 and R.sup.3 which are not alkoxy groups are C.sub.1 -C.sub.6 alkyl groups and p is 1 or more, and x is 1-50.

Abstract: An ink jet printer or a pen has a nozzle or valve (4) formed by an orifice in an elastic material (1), and the orifice comprising a slit or hole (9) in the elastic material deformable to cause the slit or hole to open or close to eject ink (2) under pressure. The printer preferably has plural, closely spaced nozzles and actuators in the form of a piezoelectric unimorph (10).

Abstract: A continuous ink jet printer printhead having an ink channel that is fed by an oscillator to a nozzle connected to the ink channel. A closer is connected within the printhead to close off the nozzle when the continuous jet ink printer is not in use.

Abstract: An ink supply system for a continuous ink jet printer gun body must allow solvent to be added during printing, and known systems are complex, requiring a pair of pumps, the output pressure of at least one of which is critical. Accordingly, to overcome these problems, an ink supply system for such a printer comprises a pump (9) for pressurising ink and air received from a gutter (8) of the printhead to a pressure above that required for ejection of the ink from the gun body (10) and an ink reservoir (1) from which fresh ink may be fed to the pump (9). The system has first (12) and second (19) chambers in combination with air space (13) and valves (14,15,25), provided for maintaining pressurised air above ink in the first chamber (12) and for controlling the pressure of air above ink in the second chamber (19). Conduit (21) is provided for supplying ink from the second chamber (19) to the printhead.

Abstract: A printhead (1) for a continuous ink jet printer has a single pair of nozzles (3,3'). One or more oscillators for vibrating the ink (3,3') may be used to break up the twin streams (4,4') of droplets issuing from the nozzles. A pair (5) of charging gates is provided for applying, selectively and respectively, a charge to droplets in the two streams (4,4'). A pair of deflector means (7) apply respective electric fields across the streams (4,4') to deflect the droplets individually in accordance with the charge thereon. A gutter (10) or pair of gutters (11,11') receive droplets from the respective streams if they are not charged. The arrangement is such that the two streams of droplets are deflected in opposite directions so as to be printed.

Abstract: A two-stage pump (9) for a continuous ink jet printing system comprises a first stage (A) which includes a chamber (91,92) having an inlet (93) and an outlet (94) via a non-return valve (115) to a channel (95). The first stage chamber (91,92) is divided by a dished diaphragm (101) movable by a first cylinder (97) mounted on a pump shaft (98). The pump (9) has a second stage (B) comprising a chamber (104,105) having an inlet (106) from the channel (95) and an outlet (107). The second stage chamber (104,105) is divided by a rolling diaphragm (116) movable by a second cylinder (108) mounted on a pump shaft (98). The cylinders (97,108) are arranged to be driven, and thus drive their respective diaphragms (101,116), 180.degree. out of phase so that ink and air enters the first stage chamber (91,92), is pressurised by the first cylinder (97) and passed through the channel (95) to the second stage chamber, and is further pressurised and passed out of the outlet (107) of the second stage chamber (104,105).

Abstract: An ink-jet ink comprises a colorant and a liquid phase consisting essentially of polymerizable monomers. For continuous printing, the ink also includes a conductive component that is soluble in the liquid phase. No methanol, ethanol, MEK or other such low molecular weight organic solvent is required.

Abstract: A printhead for a continuous ink jet printer has a body with a circular recess in an end face thereof. A circular piezoelectric transducer is disposed in the recess so as to provide a short ink chamber adjacent the face of the body and the piezoelectric transducer is arranged to expand and contract in the direction of its axis when an excitation voltage is applied to it. An ink feed channel connects with the recess for feeding ink to the ink chamber and a nozzle plate is detachably mounted on the end face of the body to eject ink under pressure when the piezoelectric transducer is actuated.

Abstract: A method of operating a continuous ink jet printing system which includes a nozzle arranged to be vibrated by a piezoelectric oscillator. The nozzle, in use, passes a stream of ink past a charging electrode. The continuity of charge detection is sensed by a charge detector disposed immediately downstream of the charging electrode. The amplitude of the stimulation voltage applied to the piezoelectric oscillator is set sufficiently low such that the level of charge detected by the charge detector is below a threshold value. The amplitude of the stimulation voltage is then increased in discrete steps until the charge detector detects intermittent and proper droplet charging. The amplitude of the stimulation voltage is then further increased from its level at the end of the second step by a predetermined amount.

Abstract: A method of and apparatus for controlling the velocity of a stream of droplets in a continuous ink jet printing system comprises controlling, from a system cabinet, the velocity of the stream expelled from the print head through a nozzle under pressure from a pressure source, in dependence upon a measured pressure of the ink in accordance with a predetermined relationship between the velocity and the pressure. On start up the system calibrates for the pressure differential P.sub.c due to the conduit length and the relative elevation of the print nozzle; and a determination of the ink viscosity in made at predetermined times. Thereafter the velocity is controlled in dependence upon a required pressure value P.sub.r in accordance with a stored look-up table, the required pressure value at any time being determined substantially by a given relationship.

Abstract: An ink jet printing head has a chamber for pressurized ink and a substantially linear array of outlet nozzles (5) leading from the chamber. A plurality of closure elements are selectively displaceable by respective actuators (13) to open and close respective ones of the nozzles. The closure elements are provided on respective flexible strips (7), each of which is fixed at one end and has the closure element at the other end and is displaceable by a respective actuator acting on the strip between its ends. At least some of the strips interdigitate with one another at their closure element-carrying ends from opposite sides of the substantially linear array of nozzles.

Abstract: A fluid jet marking apparatus comprises a housing (5) defining a chamber (6) for marking fluid. A plurality of outlet nozzles (8) allow ink to be ejected from the chamber and a corresponding plurality of closure elements (9) are selectively displaceable to open and close the nozzles. Springs (11) bias the elements to close the nozzles. A plurality of solenoids (14) are each connected to a respective closure element by means of a pulling element (12) slidable, under the action of the solenoid, in a respective tube (13,13') connecting the solenoid to the housing. A fluid supply (23) supplies fluid to the chamber and at least one liquid constituent part of the fluid is supplied to the chamber through the respective tubes (13') on which the solenoids are mounted.

Abstract: A piezo-electric ink jet droplet generator (1) has a body part (2) having a first ink supply passage (10/11) and a second ink supply passage (12) extending generally perpendicularly therefrom through a protrusion (20) of the body and opening at an end face (14) of the protrusion. A piezo-electric crystal (6) is attached to a surface of the body closely spaced from the first ink supply passage and adjacent the end of the second ink supply passage which connects with the first supply passage. A nozzle (17) is mounted in a cap (3) which is secured to the end of the protrusion (20), the nozzle being in alignment with the second supply passage (12). The inner surface (13) of the cap surrounding the nozzle is spaced from the end face (14) of the protrusion thereby forming, in use, a disk (21) of ink between the inner face of the cap and the end face of the protrusion. The cap is sealed to the protrusion by means of a flexible seal ( 16) and engaged with the protrusion by means of a quick-release coupling (9,19).