The subject disclosure is generally directed to drop emitting apparatus.
Drop on demand ink jet technology for producing printed media has been employed in commercial products such as printers, plotters, and facsimile machines. Generally, an ink jet image is formed by selective placement on a receiver surface of ink drops emitted by a plurality of drop generators implemented in a printhead or a printhead assembly. For example, the printhead assembly and the receiver surface are caused to move relative to each other, and drop generators are controlled to emit drops at appropriate times, for example by an appropriate controller. The receiver surface can be a transfer surface or a print medium such as paper. In the case of a transfer surface, the image printed thereon is subsequently transferred to an output print medium such as paper. Some ink jet printheads employ melted solid ink.
It can be difficult to reduce bubbles in the ink provided to the drop generators.
A controller 10 selectively energizes the drop generators of the printhead assembly 20 by providing a respective drive signal to each drop generator of the printhead assembly 20. Each of the drop generators can employ a piezoelectric transducer. As other examples, each of the drop generators can employ a shear-mode transducer, an annular constrictive transducer, an electrostrictive transducer, an electromagnetic transducer, or a magnetorestrictive transducer. The printhead assembly 20 can be formed of a stack of laminated sheets or plates, such as of stainless steel, having suitable openings formed therein, for example.
The recirculating ink delivery system further includes a second ink tank 17B that receives ink from the first tank 17A via a check valve 77 that permits flow only from the first tank 17A to the second tank 17B. The second tank 17B is selectively pressurizable, for example by controllably introducing pressurized air from the source of pressurized air 73 via a valve 79.
The second tank 17B is fluidically coupled to an input port 60A of a manifold structure 60, while the first ink tank 17A is fluidically coupled to an output port 60B of the manifold structure 60.
The manifold structure 60 further includes a plurality of outlets 60C that provide ink to drop generators, for example via intermediate finger manifolds 161 (
The manifold structure 60 can be implemented in the printhead assembly 20 along with the drop generators 30 and the fluidic connections between the manifold structure 60 and the drop generators 30. As described earlier, the printhead assembly 20 can comprise for example a stack of laminated sheets or plates. The first tank 17A and the second tank 17B can be attached to the printhead assembly, for example.
In normal printing operation, the first tank 17A and the second tank 17B are both vented to atmosphere, and ink 33 is appropriately introduced into the first tank 17A. Since both tanks are vented to atmosphere, ink will flow into the second tank 17B until the ink levels in both tanks 17A, 17B are substantially equalized. Ink can flow from either tank into the manifold structure 60, which in turn feeds the drop generators.
The ink in the second tank 17B can be recirculated, for example to reduce bubbles in the ink. With the ink in the tanks at a level that is less than full, for example at about half full, the second tank 17B is pressurized while the first tank is vented to atmosphere. This closes the check valve 77 which prevents ink from flowing to the second ink tank 17B, and causes ink to flow from the second tank 17B to the manifold structure. This in turn causes ink to flow from the manifold structure 60 to the first tank 17A where ink accumulates. When the first tank 17A is full or when the second tank 17B is nearly empty, for example, the second tank 17B is vented to atmosphere, which allows the ink levels to be generally equalized in the first and second tanks 17A, 17B. After the ink levels are generally equalized, the foregoing transfer can be repeated, as appropriate. In this manner, the second tank 17B comprises a source tank and the first tank comprises a sink tank, wherein ink is transferred from the source tank to the manifold structure 60, and ink is transferred from the manifold structure 60 to the sink tank.
Purging can be accomplished for example by pressurizing the first tank 17A and the second tank 17B, which forces ink to flow from the manifold to the drop generators.
A plurality of ink drop generators 30 can be fluidically connected to each finger manifold, as schematically depicted in
A plurality of ink drop generators 30 can be fluidically connected to each finger manifold, as schematically depicted in
The claims, as originally presented and as they may be amended, encompass variations, alternatives, modifications, improvements, equivalents, and substantial equivalents of the embodiments and teachings disclosed herein, including those that are presently unforeseen or unappreciated, and that, for example, may arise from applicants/patentees and others.