Patent Application
20140240416
Ink jet printers generally transport ink from an ink reservoir into a jet stack, a stack of plates that form manifolds and a pressure chamber. The ink flows through the manifolds to the pressure chamber, essentially a very small reservoir. A transducer of some sort receives an electrical signal and pushes the ink out of the pressure chamber through a nozzle to strike a printing substrate. Transporting the ink requires control over the flow rate of the ink. Dispensing the ink onto a substrate with good image quality requires that there not be any air bubbles or foreign matter in the ink that would affect the amount of ink dispensed or the integrity of the color of the ink.
Generally, controlling the flow of ink involves a weir plate. A weir plate typically controls the flow of a fluid by slowing the flow of the fluid until it reaches a bather, causing the fluid to pool up behind the plate and then eventually reach the outlet. The weir plate usually resides in the print head in a point in the flow path prior to reaching the jet stack. To remove air bubbles and foreign matter, the ink flows through a filter. The filter generally consists of two layers, one of stainless steel mesh and one of stainless steel felt.
The weir plate and the filters typically reside in the ink flow path as separate pieces. This involves attaching the two filter layers and then adding an additional weir plate after the filter. This involves three separate adhesive joints, and the additional weir plate. The added complexity to the print head increases the costs and the adhesive joints contribute possible points of failure in the printhead.
As discussed previously, current approaches to filtering ink in a print head typically use three adhesive joints, one each for each of the filters and one for the weir plate.
In the example shown, the filters and weir plate reside inside the print reservoir against the interior surface of the back wall. In the example shown, there is a recess that receives the filters 12 and 14 and the weir plate 16. As will be seen in other examples, the reservoir may not have a recess to accommodate the filter and plate, but instead may have alignment features that allow for fast and properly aligned placement of the plate or plates.
Each of these structures, 12, 14 and 16, must be adhered to the reservoir or each other independently. This involves three adhesive joints, one for each structure. This increases both the manufacturing complexity, which may increases the time and costs to produce the print head, and the number of possible points of failure in operation of the print head. The failure of the joints may result in introduction of particles into the ink flow, as well as adversely affect the pressure within the reservoir. The ink is typically pressurized to assure smooth flow out of the print head onto the print substrate and breaks in these joints may adversely affect that pressure.
The print head reservoir 10 receives ink through the ink supply port 26 into the filter plate 20. The ink travels through the filter or filters 22 and exits the filter plate through upper slots such as 24, which may be more easily seen in further pictures. After passing through the filter plate, the ink at least partially fills the reservoir formed between the reservoir plate 10 and the jet stack 30. The jet stack 30 has openings, not shown, to allow the ink to exit the reservoir into the jet stack. The jet stack ultimately routes the ink to a set of jets or nozzles that will deposit the ink on the substrate. The jet stack forms the final wall of the reservoir.
The weir plate portion of the filter sandwich plate may include dimples such as 34. As can be seen in
As a further flow control feature, the weir slots will typically reside higher in the filter sandwich plate than the incoming ink supply port, with the ink flow shown by the arrows in
In the embodiments shown here, the filters are ‘swaged’ or fit into the filter sandwich between two plates that are sealed together. While swaging is shown here, these plates may be mechanically bonded together and will typically be hermetically sealed by many different means including adhesives, brazing, soldering, etc. The filter sandwich may hold one or more filters, depending upon the filter used and the desired filtering results. In the embodiments of
Returning to
In this manner, two of the adhesive joints previously used have been eliminated. This reduces possible points of failure in the operation of the print head if those other two seals were to be breached. It also eliminates the steps of having to apply the extra adhesive. While the manufacture of the filter sandwich may increase the number of steps, the filter sandwich may be manufactured simultaneously with other steps prior to attachment. This avoids increasing the time it takes to assemble the print head.
It will be appreciated that several of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Also that 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.
