Patent Application
20110175971
This disclosure relates generally to inkjet ejectors, and, in particular, to inkjet stacks used to form inkjet ejectors for print heads used in inkjet imaging devices.
Drop on demand inkjet technology has been employed in commercial products such as printers, plotters, and facsimile machines. Generally, an inkjet image is formed by the selective activation of inkjets within a print head to eject ink onto an ink receiving member. For example, an ink receiving member rotates opposite a print head assembly as the inkjets in the print head are selectively activated. The ink receiving member may be an intermediate image member, such as an image drum or belt, or a print medium, such as paper. An image formed on an intermediate image member is subsequently transferred to a print medium, such as a sheet of paper.
Ink flows from the manifold to nozzle in a continuous path. Ink leaves the manifold 12 and travels through a port 16, an inlet 18, and a pressure chamber opening 20 into the body 22, which is sometimes called an ink pressure chamber. Ink pressure chamber 22 is bounded on one side by a flexible diaphragm 30. A piezoelectric transducer 32 is secured to diaphragm 30 by any suitable technique and overlays ink pressure chamber 22. Metal film layers 34, to which an electronic transducer driver 36 can be electrically connected, can be positioned on either side of piezoelectric transducer 32.
Ejection of an ink droplet is commenced with a firing signal. The firing signal is applied across metal film layers 34 to excite the piezoelectric transducer 32, which causes the transducer to bend. Because the transducer is rigidly secured to the diaphragm 30, the diaphragm 30 deforms to urge ink from the ink pressure chamber 22 through the outlet port 24, outlet channel 28, and nozzle 14. The expelled ink forms a drop of ink that lands onto an image receiving member. Refill of ink pressure chamber 22 following the ejection of an ink drop is augmented by reverse bending of piezoelectric transducer 32 and the concomitant movement of diaphragm 30 that draws ink from manifold 12 into pressure chamber 22.
To facilitate manufacture of an inkjet array print head, inkjet ejector 10 can be formed of multiple laminated plates or sheets. These sheets are stacked in a superimposed relationship. Referring once again to
In some newly developed inkjet ejectors, one or more of the layers may be a polymer layer. Polymers are generally non-conductive electrically. Consequently, metal plates electrically isolated by polymer layers from electrical ground may develop an electrical potential that is different than another portion of the inkjet ejector. The electrical potential difference may cause the ink flowing through the inkjet ejector to conduct a current. In some inkjet ejectors, electrical current flow in the ink may cause ink to drool or otherwise be emitted from an aperture without a firing signal being applied to the transducer for the ejector. Neutralizing electrical potential differences in an inkjet ejector would help address issues that may arise from electrical currents in an ejector.
An inkjet ejector provides electrical conductors for grounding electrically isolated layers in the ejector while electrically coupling a transducer of the ejector to a firing signal circuit. The inkjet ejector includes a diaphragm plate have a first side and a second side, a plurality of transducers mounted to the first side of the diaphragm plate, a polymer layer located on the second side of the diaphragm plate, an electrically conductive layer that is isolated from electrical ground by the polymer layer, and a plurality of electrical conductors, at least one of the electrical conductors extends from the electrically conductive layer to electrical ground through the polymer layer and other electrical conductors of the plurality of electrical conductors extend from each transducer to a firing signal circuit, the electrical conductor extending from the electrically conductive layer being the same material as the other electrical conductors in the plurality of electrical conductors.
The inkjet ejector may be made in a manner that electrically grounds the electrically isolated layers without adding more operations to the manufacturing process. The method includes bonding a plurality of transducers to a first side of a diaphragm plate, bonding a plurality of layers to a second side of the diaphragm plate, at least one of the layers in the plurality of layers being a polymer layer that electrically isolates an electrically conductive layer in the plurality of layers from electrical ground, exposing a portion of the electrically conductive layer isolated from electrical ground by the polymer layer, applying an electrically conductive material to each transducer and to the exposed portion of the electrically conductive layer in a single operation, and coupling the electrically conductive material applied to each transducer to a firing signal circuit and coupling the electrically conductive material applied to the exposed portion of the electrically conductive layer to an electrical grounding plane. Because current manufacturing techniques couple the transducers to the firing circuit, this process that couples the electrically isolated layers to electrical ground as the transducers are coupled to the firing circuit enhances the electrical integrity of the inkjet ejector without adding other manufacturing operations.
The foregoing aspects and other features of the present disclosure are explained in the following description, taken in connection with the accompanying drawings, wherein:
For a general understanding of the present embodiments, reference is made to the drawings. In the drawings, like reference numerals have been used throughout to designate like elements. As used herein, the term “imaging device” generally refers to a device for applying an image to print media. “Print media” can be a physical sheet of paper, plastic, or other suitable physical print media substrate for images. The print media may be supplied in either sheet form or as a continuously moving web. The imaging device may include a variety of other components, such as finishers, paper feeders, and the like, and may be embodied as a copier, printer, or a multifunction machine. The word “polymer” encompasses any one of a broad range of carbon-based compounds formed from long-chain molecules including thermoset polyimides, thermoplastics, resins, polycarbonates, and related compounds known to the art. As used herein, a polymer is an electrical insulator. The word “metal” may encompass either single metallic elements including, but not limited to, copper, aluminum, or titanium, or metallic alloys including, but not limited to, stainless steel or aluminum-manganese alloys. As used herein, a metal is an electrical conductor. A “transducer” as used herein is a component that reacts to an electrical signal by generating a moving force that acts on an adjacent surface or substance. The moving force may push against or retract the adjacent surface or substance.
Continuing to refer to
An outlet plate polymer layer 128 is bonded to the base of the body layer 112. This polymer layer may be composed of the same polyimide of layer 108, or another suitable polymer material. The aperture brace plate 164 is then bonded to the side of the polymer layer 128 that is not adjacent to body layer 112. The outlet plate 128 and aperture brace plate 164 enable ink to exit the print head as a droplet. The aperture brace plate 164 is a metal layer that has multiple outlet channels 172 etched through the plate, each outlet channel is aligned with an outlet port in the outlet plate to couple a pressure chamber in the body layer fluidly to an aperture 174 in the aperture layer 168. The aperture layer 168 is bonded to the aperture brace plate 164 and contains apertures or nozzles 174 that are aligned with an outlet port. The aperture layer may be made either from a metal sheet that is brazed to the aperture brace plate, or from a polymer layer that is bonded to the aperture brace plate.
Returning to the transducers of
In the embodiment of
In operation, ink flows through an ink inlet 105 and into the pressure chamber 114. An electrical firing signal passes over conductive trace 324, through conductive adhesive 238, and electrode 144 to transducer 140. A thermal transducer may heat the diaphragm 104 and thermoplastic polyimide layer 108, causing a bubble to form in the pressure chamber 114, urging ink into outlet port 115. Alternatively, a piezoelectric transducer may bend, causing the diaphragm layer 104 to deform, also urging ink into the outlet port 115. The ink then travels through outlet channel 172 and is expelled from the print head as a droplet via nozzle 174. During operation, any static electrical charges accumulated in any metal layer of the print head are dissipated by the electrical coupling of the electrically conductive layers, such as the aperture brace plate 164, body layer 112, or diaphragm 104, through the electrically conductive adhesive mass 230 and conductor 322 to electrical ground.
The various electrically conductive paths used to couple the transducers with the firing signal circuits and the electrically conductive layers with electric ground depicted in
It will be appreciated that various of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems, applications or methods. Various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.
