INK JET PRINTER

Abstract: An armature (1) for an actuator drive for a multi-jet continuous ink jet printhead has, at one side, a row of transducer mountings (10). The armature (1) has a plurality of elongate slots (5) therethrough in a row parallel to the one side, each slot (5) extending away from the one side and being aligned intermediate to the transducer mountings (10), whereby lands (6) between the slots (5) are aligned with the transducer mountings (10).

Description: Ink Jet Printer The present invention relates to ink jet printers and, more particularly, to an actuator drive for a multi-jet continuous ink jet printer. 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 non- uniformity of pressure changes across the row of orifices. According to the present invention, an actuator drive for a multi-jet continuous ink jet printhead comprises an armature having, at one side, a row of transducer mountings, the armature plate having a plurality of elongate slots therethrough in a row parallel to the one side, each slot extending away from the one side and being aligned intermediate the transducer mountings, whereby lands formed between the slots are aligned with the transducer mountings. Preferably, the number of slots is one less than the number of orifices in the printhead, so that a land is aligned with each orifice. In a preferred embodiment, the number of transducer mountings is equal to the number of orifices in the printhead, but in alternative constructions the number of transducer mountings may be less than the number of orifices. Thus, the armature may have a number of lands greater then the number of transducers employed. Preferably, the armature plate is slit at positions between the transducer mountings parallel with the slots in the armature, in order to reduce crosstalk between adjacent transducers in use. One example of an actuator drive according to the present invention will now be described with reference to the accompanying drawings in which:- Figure 1 is a plan view of an actuator drive armature; Figure 2 is a side view; Figure 3 is an underneath plan view; and, Figure 4 is an end view; Figure 5 is a view of the actuator drive armature of figure 1, together with a body; and Figure 6 is a cross-sectional view of the actuator drive armature of figure 1 connected for use. The actuator drive armature 1 comprises a stainless steel member having a mounting flange 2 by means of which the armature is secured within an ink chamber 11 defined by a body 13 and orifice plate 14. Extending perpendicularly away from the flange 2 on one side is a drive wall 3 which has a lower surface 4 which, in use, is disposed above orifices 12 in orifice plate 14 from which ink is ejected from the ink chamber 11. The drive wall 3 has a plurality of elongate slots 5 formed through it at a pitch corresponding to the pitch of the orifices 12, thereby forming a series of lands 6, each of which is disposed, in use, above a respective orifice 12. An upward extension 7 of the wall 3 is formed as a series of square-sectioned protrusions 8, separated from one another by slits 9 and having central bores 10 by means of which individual piezoelectric transducers can be mounted onto the armature in order to cause it to vibrate in use. The provision of the slots ' 5, defining the lands 6, prevents transverse flexure whilst providing for uniform energy transmission into the ink within the chamber and thus uniform generation of droplets from the row of orifices. The slits 10 between the mounting protrusions 8 act to reduce cross-talk between individual piezoelectric transducers.

Claims: CLAIMS 1. An armature for an actuator drive for a multi-jet continuous ink jet printhead, the armature having, at one side, a row of transducer mountings, characterised in that the armature has a plurality of elongate slots therethrough in a row parallel to the one side, 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. 2. An armature according to claim 1, wherein the armature has slits at positions between the transducer mountings, parallel with the slots in the armature, in order to reduce crosstalk between adjacent transducers in use. 3. A printhead having an armature according to claim 1 or claim 2, and an actuator chamber in which said armature is mounted, the chamber having a plurality of orifices for the emission of fluid droplets therefrom, wherein the number of slots in the armature is one less than the number of orifices in the chamber, so that a land is aligned with each orifice. 4. A printhead according to claim 3, wherein the number of transducer mountings is equal to the number of orifices in the chamber. 5. A printhead according to claim 3, wherein the number of transducer mountings is less than the number of orifices in the chamber.

Inventors: PALMER DANNY CHARLES, ZABA JERZY MARCIN, PALMER, DANNY, CHARLES, ZABA, JERZY, MARCIN
Applicants: DOMINO PRINTING SCIENCES PLC, PALMER DANNY CHARLES, ZABA JERZY MARCIN, PALMER, DANNY, CHARLES, ZABA, JERZY, MARCIN
Application year: 1995
Main classification: B41J2
IPC codes: B41J2