Videojet Technologies Inc.

Marconi Data Systems Limited

Graham Dagnall Martin

Nigel Edward Sherman

Sukbir Singh Pannu

Andrew D King

Amanda Hazell East

A continuous stream ink jet print head comprising: a droplet generator () for generating a continuous stream of ink droplets; a charging electrode () for selectively charging the ink droplets; deflection electrodes () for deflecting the charged ink droplets; and a catcher () for collecting uncharged ink droplets, wherein the deflection electrodes are contained within a surrounding structure () that both (i) provides surfaces () which are contoured to the shape of the main bodies of the deflection electrodes such that the main bodies may be mounted against the surfaces to correctly position the deflection electrodes within the print head, and (ii) serves as a manifold for fluid in operation of the print head, wherein the print head includes a cover () for the surrounding structure, the cover forming a wall of the space between the deflection electrodes, the wall extending along the stream of ink droplets.

Continuous stream ink jet printhead

A continuous stream binary array ink jet print head includes an elongate cavity for containing ink and an array of nozzle orifices formed so as to extend through a wall of the cavity for passing the ink from the cavity to form jets. The nozzle orifices extend along the length of the cavity. The cavity is divided up along its length by at least one internal wall thereby to create a plurality of sub-cavities substantially acoustically isolated from one another and to divide up the array of nozzle orifices between the sub-cavities such that each sub-cavity communicates with one or more of the nozzle orifices of the array. One or more actuators associated with each sub-cavity cyclically varies the dimensions of the sub-cavity thereby to cause the or each jet emanating from the nozzle orifice(s) of that sub-cavity to break up into ink droplets at a predetermined distance therefrom. The droplets of each jet are selectively electrically charged and deflected. A gutter is provided for collecting droplets not used in printing. The droplets of each jet used in printing travel along the same path to print.

Continuous stream binary array ink jet print head

A droplet generator for a continuous stream ink jet print head includes an elongate cavity for containing the ink, nozzle orifices in a wall of the cavity for passing ink from the cavity to form jets. The nozzle orifices extend along the length of the cavity. An actuator is disposed on the opposite side of the cavity to the wall for vibrating the ink in the cavity by itself vibrating relative to the wall. The vibration is such that each jet breaks up into ink droplets at the same predetermined distance from the wall of the cavity. The thickness of the wall through which the nozzle orifices extend is less than 90 &mgr;m. The wall includes a planar member secured to the remainder of the droplet generator so as to form a boundary which extends around the nozzle orifices and within which the planar member is unsupported. The boundary includes first and second boundary lengths which extend along the length of the cavity on either side of the nozzle orifices. The distance between the first and second boundary lengths being less than 1700 &mgr;m.

Droplet generator for a continuous stream ink jet print head

A continuous stream ink jet print head has a droplet generator with an elongate cavity for containing the ink, and nozzle orifices in a wall of the cavity for passing ink from the cavity to form jets. The nozzle orifices are disposed at spaced positions along the length of the cavity. An actuator for vibrating the ink in the cavity is provided such that each jet breaks up into ink droplets at the same predetermined distance from the wall of the cavity. The actuator is disposed on the opposite side of the cavity to the wall, includes a vibrator which is divided up along the length of the cavity at least partially into at least two parts, and includes a backing member disposed further from the cavity than the vibrator and secured to and bridging the parts into which the vibrator is at least partially divided. The vibrator is interposed in line between the backing member and the cavity.

Continuous stream ink jet print head droplet generator having backing member bridging divided vibrator

In a first aspect, in a continuous stream ink jet printing system generating a plurality of streams of ink droplets, a chosen number of droplets of each stream is less than all of the droplets of the stream. A controller of the printing system is arranged to consider for printing from among a number of the droplets of each stream greater than the chosen number with the proviso that the resultant selection made observes this constraint. In second and third aspects, the controller of the printing system is arranged to create a set of droplet print positions ideal for representing an image to be printed, which set is permitted to include print positions offset from print positions of a nominal matrix, at speeds of operation less than the predetermined speed. The controller compares the positions at which droplets are deposited at the lower speed with the set of ideal positions. The controller decides which droplets to print in dependence on the comparison.

Ink jet printing system

A droplet generator for a continuous stream ink jet print head has a cavity for containing ink, and nozzle orifices passing ink from the cavity to form jets. An actuator means vibrates the ink in the cavity such that each jet breaks up into ink droplets. The actuator means is disposed on the opposite side of the cavity to the nozzle orifices, and a surrounding wall of the cavity extends between the actuator means and nozzle orifices for containing the ink therebetween. The surrounding wall has inner and outer constituent wall. The resistive component of the wave impedance of the outer wall passively damps vibration of the inner wall by dissipating its vibration; the reactive component of the wave impedance of the outer wall actively restrains vibration of the inner wall, ensuring that each jet breaks up into ink droplets at the same predetermined distance from its respective nozzle orifice.

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Sawston, United Kingdom

Graham Dagnall Martin