Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1999-08-20
2001-07-03
Tran, Huan (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06254224
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to ink jet printers and, more particularly, to an actuator drive for a multi-jet continuous ink jet (CIJ) printer.
BACKGROUND OF THE INVENTION
In a multi-jet continuous ink jet printer, in order to create streams of droplets issuing through multiple nozzles or orifices, it is known to pressure modulate the fluid by means of plural piezoelectrically actuated drive rods or else by a single piezoelectrically actuated armature. A problem associated with plural drive rods is the need to ensure syncronicity between the independent drive rods so that they are all vibrating in phase. A problem with a single armature causing jets to issue through a row of orifices is that of preventing transverse flexure and nonuniformity of pressure changes across the row of orifices.
It is also known, in a multi-jet continuous inkjet printer, to create streams of droplets by means of the velocity modulator or resonator as shown in U.S. Pat. No. 4,999,647. In U.S. Pat. No. 4,999,647 a resonator is shown with elongate slots disposed between transducers mounted within the resonator and an ink passage passes through the resonator and communicates with orifices in an orifice plate bonded to one side of the resonator. In WO-A-96-12622we describe a multi-jet continuous ink jet printhead having an ink chamber, the chamber having a plurality of orifices for the emission of fluid droplets therefrom, and an actuator drive armature with a plurality of elongate slots therethrough disposed in a row, characterised in that the armature is disposed within the ink chamber, and has a row of transducer mountings at one side and a drive wall at the other side, the slots being disposed in the drive wall in a row parallel-to the one side of the armature, and each slot extending away from the one side and being aligned intermediate the transducer mountings, whereby lands between the slots are aligned with the transducer mountings.
SUMMARY OF THE INVENTION
According to a first aspect of the present invention there is provided a multi-jet continuous ink jet printhead droplet generator having an ink chamber, the chamber having a plurality of orifices for the emission of fluid droplets therefrom, and an actuator drive armature disposed within the ink chamber, the actuator drive armature having a one piece solid drive wall at one side and a single pair of transducer mountings at the other side, the transducer mountings being disposed adjacent respective ends of the drive wall.
With a one-piece, ie non-split drive wall, fabrication is simpler and the same benefit is provided by having only a single pair of transducer mountings. It has been found in practice that having the transducers mounted adjacent the ends of the drive wall, as opposed to being equidistantly arranged over the length of the drive wall, provides an improved drive wall response.
The drive wall may have a pair of major faces which are tapered towards one another in the direction away from the other side.
Tapering the major faces towards one another results in a gradual narrowing of the drive wall which, in turn, causes it to act as a velocity transformer, increasing the efficiency of the energy transfer from the actuator transducer(s) disposed at the other side of the actuator drive armature.
The tapered major faces may be produced by a machining method which machines the faces continuously, in which case, the minor or end faces of the drive wall my also be tapered towards one another.
REFERENCES:
patent: 4095232 (1978-06-01), Cha
patent: 4138687 (1979-02-01), Cha et al.
patent: 4324117 (1982-04-01), Schwob et al.
patent: 4528571 (1985-07-01), Sweet
patent: 5502473 (1996-03-01), East et al.
patent: 5912686 (1999-06-01), Palmer et al.
patent: 0 709 194A1 (1996-05-01), None
patent: WO 96/12622 (1996-05-01), None
Lecheheb Ammar
Tomlin Matthew
Conte Robert F. I.
Domino Printing Sciences PLC
Lee Mann Smith McWilliams Sweeney & Ohlson
Tran Huan
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