Flow-Through Printhead

Abstract

To provide a print head for jetting a printing fluid.SOLUTION: A flow through type print head includes a plurality of jet channels arranged in a first row and a second row which are substantially parallel to each other along the length of the print head, wherein each of the jet channels includes a diaphragm, a pressure chamber, and nozzles configured to jet a printing fluid. The flow through type print head further includes a first manifold which is fluidly coupled to the jet channel of the first row, and a second manifold which is fluidly coupled to the jet channel of the first row. The first manifold and the second manifold are arranged on both sides of the first row, and the second manifold is arranged in an intermediate region between the first row and the second row.SELECTED DRAWING: Figure 5A

Description

[Technical field]

[0001] The following disclosure relates to the field of imaging, and more particularly to printheads and / or printhead designs. [Background technology]

[0002] Imaging is a procedure in which a digital image (e.g., a 2D image, a 3D image or model, etc.) is reproduced by ejecting droplets of ink or another type of printing fluid onto a medium such as paper, plastic, a substrate for 3D printing, etc. Imaging is commonly used in devices such as printers (e.g., inkjet printers, 3D printers, etc.), facsimile machines, copiers, plotting machines, multifunction peripherals, etc. The core of a typical ejection or imaging device is one or more droplet ejection heads (commonly referred to herein as "printheads") having nozzles that eject droplets, mechanisms for moving the printheads and / or the medium relative to one another, and a controller that controls how fluid is ejected from the individual nozzles of the printheads onto the medium in the form of pixels.

[0003] A typical printhead includes a number of nozzles aligned in one or more rows along the printhead's ejection face. Each nozzle is part of an "ejection channel" that includes a nozzle, a pressure chamber, and a diaphragm that vibrates in response to an actuator, such as a piezoelectric actuator. The printhead also includes driver circuitry that controls when each individual ejection channel fires based on image or print data. To eject from an ejection channel, the driver circuit provides one or more ejection pulses to the actuator, which causes the actuator to deform the walls (i.e., the diaphragm) of the pressure chamber. The deformation of the pressure chamber creates a pressure wave within the pressure chamber that ejects one or more droplets of printing fluid (e.g., ink) from the nozzle.

[0004] Nozzle failures can occur in printheads due to a variety of factors such as drying of the printing fluid at the nozzle or meniscus, buildup of the printing fluid, air bubbles present in the printing fluid, etc. These and other nozzle failures can result in degraded print quality. Summary of the Invention

[0005] The embodiments described herein provide a flow-through printhead and related methods of using the printhead. In one embodiment, the flow-through printhead includes ejection channels arranged in adjacent rows. The first row of ejection channels are fluidly coupled to a first manifold and a second manifold arranged on either side of the first row. In other words, the second manifold is disposed between the rows of ejection channels. Thus, the second manifold is disposed in an area of ​​the printhead between adjacent rows of ejection channels that was previously unused, allowing printing fluid to circulate through the ejection channels. One technical advantage is that the printing fluid may circulate through the ejection channels to avoid drying or deposition of the printing fluid in the ejection channels, which provides improved jetting consistency and performance. Another technical advantage is that the printhead may be constructed with fewer laminates, which reduces manufacturing costs and allows for higher frequency jetting.

[0006] In one embodiment, the flow-through printhead includes a plurality of ejection channels arranged in first and second rows generally parallel along a length of the printhead, each of the ejection channels including a diaphragm, a pressure chamber, and a nozzle configured to eject a printing fluid. The flow-through printhead further includes a first manifold fluidly coupled to the ejection channels in the first row and a second manifold fluidly coupled to the ejection channels in the first row. The first and second manifolds are disposed on opposite sides of the first row, and the second manifold is disposed in an intermediate region between the first and second rows.

[0007] In one embodiment, a flow-through printhead includes a housing and a plate stack attached to the housing forming a plurality of ejection channels arranged in first and second rows generally parallel along a length of the printhead. Each of the ejection channels includes a diaphragm, a pressure chamber, and a nozzle configured to eject a printing fluid. The plate stack forms a first manifold arranged longitudinally and fluidly coupled to the ejection channels of the first row. It forms a second manifold arranged longitudinally and fluidly coupled to the ejection channels of the first row. The first and second manifolds are arranged on either side of the first row, and the second manifold is arranged in an intermediate region between the first and second rows.

[0008] In one embodiment, a method includes operating a flow-through printhead including a plurality of ejecting channels arranged in first and second rows generally parallel along a length of the printhead, each of the ejecting channels including a diaphragm, a pressure chamber, and a nozzle configured to eject printing fluid, further including a first manifold fluidly coupled to the ejecting channels of the first row, and further including a second manifold fluidly coupled to the ejecting channels of the first row. The first and second manifolds are disposed on opposite sides of the first row, and the second manifold is disposed in an intermediate region between the first and second rows. Operating the flow-through printhead includes, for each ejecting channel of the first row, conveying printing fluid from the first manifold on a first side of the first row to a pressure chamber, and, for each ejecting channel of the first row, conveying non-ejected printing fluid from the pressure chamber to a second manifold on a second side of the first row opposite the first side.

[0009] The above summary provides a basic understanding of some aspects of the specification. This summary is not an extensive overview of the specification. It is not intended to identify key or critical elements of the specification, nor to delineate the scope or claims of particular embodiments of the specification. Its sole purpose is to present some concepts of the specification in a simplified form as a prelude to the more detailed description that is presented later. [Brief description of the drawings]

[0010] Some embodiments of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which the same reference signs represent the same elements or same types of elements, and in which: [Figure 1] FIG. 2 is a schematic diagram of an injection device in an exemplary embodiment. [Diagram 2] FIG. 2 is a perspective view of a printhead in an exemplary embodiment. [Diagram 3] FIG. 2 is a perspective view of a printhead in an exemplary embodiment. [Figure 4] FIG. 2 is a cross-sectional view of a printhead in an exemplary embodiment. [Figure 5A] FIG. 2 is a schematic diagram of a print head in an exemplary embodiment. [Figure 5B] FIG. 2 is a schematic diagram of a print head in an exemplary embodiment. [Figure 5C] FIG. 2 is a schematic diagram of a print head in an exemplary embodiment. [Figure 5D] FIG. 2 is a schematic diagram of a print head in an exemplary embodiment. [Figure 6A] FIG. 2 is a cross-sectional view of a portion of a printhead in an exemplary embodiment. [Figure 6B] FIG. 2 is a cross-sectional view of a portion of a printhead in an exemplary embodiment. [Figure 7] FIG. 2 is a perspective view of an injection channel in an exemplary embodiment; [Figure 8] 1 illustrates an exploded perspective view of a head member of a printhead in an exemplary embodiment. [Figure 9] 1 illustrates a chamber plate in an exemplary embodiment. [Figure 10] 1 illustrates a chamber plate in an exemplary embodiment. [Figure 11] FIG. 2 is a cross-sectional view of a portion of a printhead in an exemplary embodiment. [Figure 12] 4 is a flowchart illustrating a method of operating a print head in an example embodiment. [Figure 13] FIG. 2 is a perspective view of an injection channel having one or more in-channel passive mixers in an exemplary embodiment. [Figure 14A] FIG. 13 is a top view of an in-channel passive mixer in an injection channel in an exemplary embodiment; [Figure 14B] FIG. 13 is a top view of an in-channel passive mixer in an injection channel in an exemplary embodiment; [Figure 14C] FIG. 13 is a top view of an in-channel passive mixer in an injection channel in an exemplary embodiment; [Figure 14D] FIG. 13 is a top view of an in-channel passive mixer in an injection channel in an exemplary embodiment; [Figure 14E] FIG. 13 is a top view of an in-channel passive mixer in an injection channel in an exemplary embodiment; [Figure 14F] FIG. 13 is a top view of an in-channel passive mixer in an injection channel in an exemplary embodiment; [Figure 14G] FIG. 13 is a top view of an in-channel passive mixer in an injection channel in an exemplary embodiment; [Figure 14H] FIG. 13 is a top view of an in-channel passive mixer in an injection channel in an exemplary embodiment; [Figure 15] 1 illustrates a restrictor plate in an exemplary embodiment. [Figure 16] 1 illustrates a chamber plate in an exemplary embodiment. [Figure 17] 5 is a flowchart illustrating a method of operating a printhead having one or more intra-channel passive mixers in an example embodiment. [Figure 18] FIG. 2 is a perspective view of an injection channel having one or more in-chamber active mixers in an exemplary embodiment. [Figure 19] FIG. 2 is a perspective view of an in-chamber active mixer in an exemplary embodiment. [Figure 20] FIG. 13 is a perspective view of an in-chamber active mixer in another exemplary embodiment. [Figure 21A] FIG. 2 is a top view of a pressure chamber having one or more in-chamber active mixers in an exemplary embodiment. [Figure 21B] FIG. 2 is a top view of a pressure chamber having one or more in-chamber active mixers in an exemplary embodiment. [Figure 21C] FIG. 2 is a top view of a pressure chamber having one or more in-chamber active mixers in an exemplary embodiment. [Figure 21D] FIG. 2 is a top view of a pressure chamber having one or more in-chamber active mixers in an exemplary embodiment. [Figure 21E] FIG. 2 is a top view of a pressure chamber having one or more in-chamber active mixers in an exemplary embodiment. [Figure 21F] FIG. 2 is a top view of a pressure chamber having one or more in-chamber active mixers in an exemplary embodiment. [Figure 21G] FIG. 2 is a top view of a pressure chamber having one or more in-chamber active mixers in an exemplary embodiment. [Fig. 21H] FIG. 2 is a top view of a pressure chamber having one or more in-chamber active mixers in an exemplary embodiment. [Figure 21I] FIG. 2 is a top view of a pressure chamber having one or more in-chamber active mixers in an exemplary embodiment. [Figure 22] 1 illustrates a chamber plate in an exemplary embodiment. [Diagram 23] 1 is a flowchart illustrating a method of operating a printhead having an in-chamber active mixer in an example embodiment. [Figure 24] FIG. 1 illustrates a perspective view of an injection channel having an in-channel fluid mixer in an exemplary embodiment; [Figure 25A] 1 illustrates an in-channel fluid mixer in an exemplary embodiment. [Figure 25B] 1 illustrates an in-channel fluid mixer in an exemplary embodiment. [Figure 25C] 1 illustrates an in-channel fluid mixer in an exemplary embodiment. [Figure 25D] 1 illustrates an in-channel fluid mixer in an exemplary embodiment. [Figure 26] 1 illustrates a chamber plate in an exemplary embodiment. [Figure 27] 1 illustrates a chamber plate in an exemplary embodiment. [Figure 28] 5 is a flowchart illustrating a method of operating a printhead having an in-channel fluid mixer in an example embodiment. [Figure 29] FIG. 2 is a cross-sectional view of a flow-through printhead in an exemplary embodiment. [Diagram 30] FIG. 2 is a cross-sectional view of a non-flow-through printhead in an exemplary embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The drawings and the following description show specific exemplary embodiments. Therefore, it is recognized that those skilled in the art can devise various configurations that embody the principles of the embodiments and fall within the scope of the embodiments, although not explicitly described or shown herein. Furthermore, any examples described herein are intended to help understand the principles of the embodiments, and should be construed as not being limited to such specifically listed examples and conditions. As a result, the concept of the present invention is not limited to the specific embodiments or examples described below, but is limited by the claims and their equivalents.

[0012] FIG. 1 is a schematic diagram of an ejection apparatus 100 in an exemplary embodiment. The ejection apparatus 100 is a device or system that uses one or more printheads to eject printing fluid or marking material onto a medium. One example of the ejection apparatus 100 is an inkjet printer (e.g., continuous feed or cut sheet printer) that performs single pass printing. Other examples of the ejection apparatus 100 include scan path inkjet printers (e.g., wide format printers), multifunction printers, desktop printers, industrial printers, 3D printers, etc. In general, the ejection apparatus 100 includes a mounting mechanism 102 that supports one or more printheads 104 relative to a medium 112. The mounting mechanism 102 may be fixed within the ejection apparatus 100 for single pass printing. Alternatively, the mounting mechanism 102 may be disposed on a carriage assembly that reciprocates back and forth along a scan line or sub-scan direction for multi-pass printing. The printhead 104 is a device, apparatus, or component configured to eject droplets 106 of a printing fluid such as ink (e.g., water, solvent, oil, or UV curable) through multiple nozzles (not visible in FIG. 1). Droplets 106 ejected from nozzles of the printhead 104 are directed toward a medium 112. The medium 112 comprises any type of material to which ink or another printing or jetting fluid is applied by the printhead, such as paper, plastic, card stock, transparencies, substrates for 3D printing, fabric, etc. Typically, the nozzles of the printhead 104 are arranged in one or more rows such that ejection of printing fluid from the nozzles causes the formation of characters, symbols, images, layers of objects, etc. on the medium 112 as the printhead 104 and / or the medium 112 move relative to one another. The jetting device 100 may include a media transport mechanism 114 or a media-holding bed 116. The media transport mechanism 114 is configured to move the medium 112 relative to the printhead 104. The media-holding bed 116 (e.g., a platen) is configured to support the medium 112 in a stationary position while the printhead 104 moves relative to the medium 112.

[0013] The ejection device 100 also includes an ejector controller 122 that controls the overall operation of the ejection device 100. The ejector controller 122 may connect to a data source to receive print jobs, print data, image data, etc., and control each printhead 104 to eject printing fluid onto the media 112. The ejection device 100 also includes one or more reservoirs 124 for the printing fluid or types of printing fluid. Although not shown in FIGURE 1, the reservoirs 124 are fluidly coupled to the printheads 104 using hoses or the like.

[0014] FIG. 2 is a perspective view of the printhead 104 in an exemplary embodiment. In this embodiment, the printhead 104 includes a head member 202 and electronics 204. The head member 202 is an elongated component that forms the ejection channels of the printhead 104. A typical ejection channel includes a nozzle, a pressure chamber, and a diaphragm that is driven by an actuator, such as a piezoelectric actuator. The electronics 204 controls how the nozzles of the printhead 104 eject droplets in response to data and control signals received from another controller (e.g., the ejector controller 122). The electronics 204 includes an embedded printhead controller or driver circuit configured to drive the individual ejection channels based on the data and control signals. The bottom surface of the head member 202 in FIG. 2 includes the nozzles of the ejection channels and represents the ejection surface 220 of the printhead 104. The top surface of the head member 202 in FIG. 2 (referred to as I / O surface 222) represents an input / output (I / O) portion for receiving one or more printing fluids to the printhead 104 and / or transporting printing fluids (e.g., non-jetted fluids) from the printhead 104. The I / O surface 222 includes a number of I / O ports 211-214. The I / O ports 211-214 may include inlet I / O ports, which are openings in the head member 202 that function as inlets or entry points for printing fluids. The I / O ports 211-214 may include outlet I / O ports, which are openings in the head member 202 that function as outlets or exit points for printing fluids. The I / O ports 211-214 may include hose fittings, hose barbs, etc. for coupling with hoses for reservoirs, cartridges, etc. The number of I / O ports 211-214 is provided by way of example only and the printhead 104 may include other numbers of I / O ports.

[0015] Generally, the head member 202 includes a housing 230 and a plate stack 232. The housing 230 is a rigid member made from stainless steel or another type of material. The housing 230 includes an access hole 234 that provides a passage for the electronics 204 to pass through the housing 230 so that the actuator can mate (i.e., contact) with the diaphragm of the ejection channel. The plate stack 232 is attached to a mating surface (not visible) of the housing 230. The plate stack 232 (also called a stacked plate stack) is a series of plates secured or bonded together to form a stacked stack. The plate stack 232 may include plates such as one or more nozzle plates, one or more chamber plates, one or more restrictor plates, a support (or support) plate, and a diaphragm plate. The nozzle plate includes a plurality of nozzles arranged in one or more rows. The chamber plate includes a plurality of openings that form pressure chambers of the ejection channels. The restrictor plate includes a plurality of openings that form restrictors for fluidly coupling the pressure chambers of the ejection channels to a manifold. The diaphragm plate is a sheet of semi-flexible material that vibrates in response to actuation by an actuator (eg, a piezoelectric actuator).

[0016] FIG. 2 illustrates one particular configuration of printhead 104, and it is understood that other printhead configurations having multiple ejecting channels are also contemplated herein.

[0017] FIG. 3 is a perspective view of the printhead 104 in an exemplary embodiment. In one embodiment, the head member 202 is an assembly including a housing 230 and a plate stack 232 fixed or attached to the housing 230. The plate stack 232 is an elongated stack having a length 350 (i.e., along the x-axis) and a width 352 (i.e., along the y-axis). In this description, the x-axis is along the length 350 of the printhead 104 and may be referred to as the x-direction, lengthwise direction, longitudinal direction, etc. The y-axis is along the width 352 of the printhead 104 and may be referred to as the y-direction, widthwise direction, lateral direction, etc. The z-axis is along the height of the printhead 104 and may be referred to as the z-direction, height direction, etc. The plate stack 232 includes one or more nozzle plates 304 having orifices that form nozzles 306 of the ejection channels. The bottom surface of the nozzle plate 304 thus defines the ejection face 220 of the printhead 104. The nozzles 306 are shown in Figure 3 with two rows of nozzles arranged longitudinally along the length 350 of the plate stack 232 and generally parallel to the longitudinal sides 312-313 of the printhead 104 / plate stack 232. A longitudinal centerline 310 of the printhead 104 / plate stack 232 is shown along the x-axis between adjacent rows of ejection channels (represented by their corresponding nozzles) and represents the axis of symmetry between the rows. Although two rows of nozzles 306 are shown in Figure 3, in other embodiments the ejection channels and their corresponding nozzles 306 may be arranged in more than one or two rows.

[0018] FIG. 4 is a cross-sectional view of a printhead 104 in an exemplary embodiment. FIG. 4 shows a cross-section of a portion of a row of ejection channels 402 along section plane 4-4 of FIG. 3. The ejection channels 402 are structural elements in the printhead 104 configured to eject or dispense printing fluid. Each ejection channel 402 includes a diaphragm 410, a pressure chamber 412 (also called a Helmholtz chamber), and a nozzle 306. An actuator 416 contacts the diaphragm 410 to control ejection from the ejection channel 402. The ejection channels 402 may be formed in a row along the length 350 of the printhead 104 (i.e., the plate stack 232), and each ejection channel 402 may have a configuration similar to that shown in FIG. 4.

[0019] 5A-5D are schematic diagrams of a printhead 104 in an exemplary embodiment. In FIG. 5A, the printhead 104 may be a flow-through printhead 504 in which printing fluid may circulate through the ejection channels 402 past their corresponding nozzles 306. Thus, the ejection channels 402 themselves may be referred to as flow-through ejection channels 540. The rows 501-502 of ejection channels 402 in the printhead 104 are shown diagrammatically in FIG. 5A as rows of nozzles 306. Generally, the multiple ejection channels 402 for the printhead 104 are arranged in rows 501-502 that are arranged longitudinally (i.e., along the x-axis) along the length 350 of the printhead 104 and are generally parallel to one another. The printhead 104 includes manifolds 510-511 and 514-515. A manifold is a common conduit or channel within the printhead 104 (i.e., within the housing 230 and / or the plate stack 232) that provides a common flow path for multiple ejection channels 402. In the row 501, for example, each ejection channel 402 may be fluidly coupled to a manifold 510-511. In one embodiment, the manifold 510 may be referred to as a supply manifold when configured or operated to supply printing fluid to a set of ejection channels 402 in the row 501. The manifold 510 may be fluidly coupled between the I / O ports 211-212, for example, to receive printing fluid from an external source, and may function as a common supply conduit capable of supplying printing fluid to multiple ejection channels 402. The manifold 511 may be referred to as a return manifold when configured or operated to receive printing fluid from the ejection channels 402 in the row 501. Printing fluid that is not ejected from the nozzles 306 of the ejection channels 402 may be referred to herein as "non-ejected printing fluid." Thus, a manifold that receives printing fluid from the ejecting channels 402 may be referred to herein as receiving non-jetting printing fluid. The manifold 511 may function as a common return conduit capable of receiving non-jetting printing fluid from multiple ejecting channels 402 in the row 501.Manifold 511 is fluidly coupled to manifold 510 through injection channels 402 of row 501 and may also be fluidly coupled to manifold 510 through one or more inter-manifold fluid passages 512 .

[0020] In the row 502, for example, each ejecting channel 402 may be fluidly coupled to a manifold 514-515. In one embodiment, the manifold 514 may be referred to as a supply manifold when configured or operated to supply printing fluid to a set of ejecting channels 402 in the row 502. The manifold 514 may be fluidly coupled between the I / O ports 213-214, for example, to receive printing fluid from an external source, and may function as a common supply conduit capable of supplying printing fluid to the multiple ejecting channels 402. The manifold 515 may be referred to as a return manifold when configured or operated to receive printing fluid from the ejecting channels 402 in the row 502. The manifold 515 may function as a common return conduit capable of receiving non-ejected printing fluid from the multiple ejecting channels 402 in the row 502. Manifold 515 is fluidly coupled to manifold 514 through injection channels 402 of row 502 and may also be fluidly coupled to manifold 510 through one or more inter-manifold fluid passages 516 .

[0021] Manifolds 510 and 514 may be referred to herein as supply manifolds, and manifolds 511 and 515 may be referred to herein as return manifolds, although the flow of printing fluid may be reversed within printhead 104. Thus, when the flow is reversed (i.e., opposite to the flow shown in FIG. 5A), manifolds 510 and 514 may comprise return manifolds, and manifolds 511 and 515 may comprise supply manifolds.

[0022] 5A, each ejection channel 402 is a flow-through type ejection channel 540 having an independent flow path to and from the pressure chamber 412 that is not shared or common with another ejection channel 402. For example, each ejection channel 402 in the row 501 includes a channel fluid passage 520 (also called a channel fluid conduit) between the manifold 511 and the pressure chamber 412 of the ejection channel 402 (see also FIG. 4), and also includes a channel fluid passage 521 between the pressure chamber 412 of the ejection channel 402 and the manifold 510. The channel fluid passages 520-521 represent separate paths for printing fluid to flow, for example, from the manifold 510 to the pressure chamber 412, and for (non-ejected) printing fluid to flow from the pressure chamber 412 to the manifold 511 (or vice versa).

[0023] Similarly, each ejection channel 402 in a column 502 includes a channel fluid passage 520 between the manifold 514 and the pressure chamber 412 of the ejection channel 402 (see also FIG. 4), and also includes a channel fluid passage 521 between the pressure chamber 412 of the ejection channel 402 and the manifold 515. The channel fluid passages 520-521 represent separate paths for printing fluid to flow, for example, from the manifold 514 to the pressure chamber 412, and for (non-ejected) printing fluid to flow from the pressure chamber 412 to the manifold 515 (or vice versa).

[0024] In one embodiment, major portions or sections of manifolds 510-511 and 514-515 are positioned longitudinally (i.e., along the x-axis) within printhead 104 to fluidly couple with ejecting channels 402 arranged in rows 501-502. In some flow-through printheads, the return manifold is positioned longitudinally on the same side of the row of ejecting channels as the supply manifold. In one embodiment herein, manifolds 510-511 are positioned on either side of row 501 of ejecting channels 402. Similarly, manifolds 514-515 are positioned on either side of row 502 of ejecting channels 402. To illustrate this configuration, longitudinal sides 312-313 of printhead 104 are shown. The manifold 510 is disposed on one side 570 (i.e., first side) of the row 501 of ejection channels 402 between the longitudinal side 312 and the row 501, and the manifold 511 is disposed on the other side 572 (i.e., second side) of the row 501 of ejection channels 402 between adjacent rows 501-502 (i.e., between the row 501 and the longitudinal centerline 310). A "side" of a row of ejection channels 402 includes a longitudinal side along the length of the row. The manifold 511 is disposed in an intermediate region 550 between the rows 501-502 of ejection channels 402, as well as the channel fluid passages 521 of the individual ejection channels 402 within the row 501. Similarly, manifold 514 is disposed on one side 574 (i.e., first side) of row 502 of ejection channels 402 between longitudinal side 313 and row 502, and manifold 515 is disposed on the other side 576 (i.e., second side) of row 502 of ejection channels 402 between adjacent rows 501-502 (i.e., between row 502 and longitudinal centerline 310). Manifold 515 is disposed in intermediate region 550 between rows 501-502, as are channel fluid passages 521 of individual ejection channels 402 of row 502. Thus, manifold 511 is disposed between row 501 and manifold 515, and manifold 515 is disposed between row 502 and manifold 511.

[0025] In Figure 5B, manifold 510 may be fluidly coupled to I / O port 211, for example, to receive printing fluid from an external source, and manifold 511 may be fluidly coupled to I / O port 212, for example, to provide an exit path for printing fluid from print head 104 to an external container. Similarly, manifold 514 may be fluidly coupled to I / O port 213, for example, to receive printing fluid from an external source, and manifold 515 may be fluidly coupled to I / O port 214, for example, to provide an exit path for printing fluid from print head 104 to an external container. It will be understood that for simplicity, the concepts discussed above with respect to Figure 5A apply to the configuration of Figure 5B.

[0026] In Figure 5C, print head 104 may include additional I / O ports 591-594. For example, manifold 510 may be fluidly coupled to I / O ports 211-212, manifold 511 may be fluidly coupled to I / O ports 591-592, manifold 514 may be fluidly coupled to I / O ports 213-214, and manifold 515 may be fluidly coupled to I / O ports 593-594. It will be understood that for simplicity, the concepts discussed above with respect to Figure 5A apply to the configuration of Figure 5C.

[0027] In the configurations shown in Figures 5A-5C, the print head 104 may be operated to eject a single type of printing fluid (e.g., a single color) or two different types of printing fluid (e.g., two colors). However, the print head 104 may be configured to eject more types of printing fluid. Figure 5D is a schematic diagram of the print head 104 in an exemplary embodiment. In this embodiment, the print head 104 includes manifolds 510-511, 514-515, 530-531, and 534-535. In row 501, a subset of the ejecting channels 402 is fluidically coupled to the manifolds 510-511, and a subset of the ejecting channels 402 is fluidically coupled to the manifolds 530-531. In row 502, a subset of the ejecting channels 402 is fluidically coupled to the manifolds 514-515, and a subset of the ejecting channels 402 is fluidically coupled to the manifolds 534-535. It will be understood that for simplicity, the concepts discussed above with respect to Figure 5A apply to the configuration of Figure 5D. In the configuration shown in Figure 5D, the print head 104 may be operated to eject a single type of printing fluid (e.g., a single color), two different types of printing fluid (e.g., two colors), or four different types of printing fluid (e.g., four colors).

[0028] One or more methods may be used to circulate the printing fluid through the ejecting channels 402 of the printhead 104. For example, the pressure in manifold 510 and / or manifold 511 may be adjusted to create a pressure differential between manifolds 510-511. The pressure differential causes the printing fluid to flow through the ejecting channels 402 of row 501. Similarly, the pressure in manifold 514 and / or manifold 515 may be adjusted to create a pressure differential between manifolds 514-515. The pressure differential causes the printing fluid to flow through the ejecting channels 402 of row 502.

[0029] 6A-6B are cross-sectional views of a portion of a printhead 104 in an exemplary embodiment. FIGS. 6A-6B show a cross-section of the printhead 104 along section plane 6-6 of FIG. 3. In FIG. 6A, two ejection channels 402 are shown in adjacent rows 501-502. Similar to FIG. 4, the ejection channels 402 include a diaphragm 410, a pressure chamber 412, and a nozzle 306 (note that the nozzle 306 of the ejection channel 402 of row 502 is not visible in this cross-section). A manifold 510 of the printhead 104 is fluidly coupled to the ejection channels 402 of row 501. More specifically, the pressure chamber 412 of the ejection channel 402 is fluidly coupled to the manifold 510 through a channel fluid passage 520. In one embodiment, the channel fluid passage 520 may include a restrictor that controls or regulates the flow of printing fluid between the manifold 510 and the pressure chamber 412 along the channel fluid passage 520. The pressure chamber 412 of the ejection channel 402 is also fluidly coupled to the manifold 511 through a channel fluid passage 521 .

[0030] A manifold 514 of the printhead 104 is fluidly coupled to the ejecting channels 402 of the columns 502. More specifically, the pressure chambers 412 of the ejecting channels 402 are fluidly coupled to the manifold 514 through channel fluid passages 520. In one embodiment, the channel fluid passages 520 may include restrictors that control the flow of printing fluid between the manifold 514 and the pressure chambers 412 along the channel fluid passages 520. The pressure chambers 412 of the ejecting channels 402 are also fluidly coupled to the manifold 515 through channel fluid passages 521.

[0031] 6A, row 501 of ejection channels 402 and row 502 of ejection channels 402 are adjacent to one another in the printhead 104 and are separated by the longitudinal centerline 310. Manifolds 511 and 515 are disposed in a middle region 550 of the printhead 104 / plate stack 232 between rows 501-502 of ejection channels 402. More specifically, manifolds 511 and 515 are disposed between the pressure chambers 412 of the ejection channels 402 of adjacent rows 501-502. For row 501 of ejection channels 402, manifold 510 is disposed on one side (along the y-axis) of the pressure chambers 412 in an outer region 652 of the printhead 104 / plate stack 232 between row 501 of ejection channels 402 and longitudinal side 312. Manifold 510 is fluidly coupled to pressure chamber 412 via channel fluid passages 520, also disposed in outer region 652. Manifold 511 is disposed on the other side of pressure chamber 412 (relative to manifold 510) along the y-axis within intermediate region 550. Manifold 511 is disposed between pressure chamber 412 and longitudinal centerline 310 and may be fluidly isolated from manifold 515 and / or injection channels 402 of row 502.

[0032] For the ejection channels 402 of the row 502, the manifold 514 is disposed on one side (along the y-axis) of the pressure chambers 412 in an outer region 654 of the printhead 104 / plate stack 232 between the row 502 and the longitudinal side 313 of the ejection channels 402. The manifold 514 is fluidly coupled to the pressure chambers 412 via channel fluid passages 520 also disposed in the outer region 654. The manifold 515 is disposed on the other side of the pressure chambers 412 along the y-axis (relative to the manifold 514) in the middle region 550. The manifold 515 is disposed between the pressure chambers 412 and the longitudinal centerline 310 and may be fluidically isolated from the manifold 511 and / or the ejection channels 402 of the row 501.

[0033] FIG. 6B shows a cross section of an ejection channel 402 of a row 501. The arrows in FIG. 6B show the flow of printing fluid from the manifold 510 to the ejection channel 402 and from the ejection channel 402 to the manifold 511. The printing fluid 680 flows from the manifold 510 through the channel fluid passages 520 to the pressure chamber 412. One wall of the pressure chamber 412 is formed by a diaphragm 410 that physically interfaces with an actuator 416. The diaphragm 410 may include a sheet of semi-flexible material that vibrates in response to actuation by the actuator 416. To eject from the ejection channel 402, one or more ejection pulses are sent to the actuator 416, and the actuator 210 actuates or "fires" in response to the ejection pulses. The firing of the actuator 416 creates a pressure wave in the pressure chamber 412 that causes the ejection of one or more droplets from the nozzle 306. Non-ejected printing fluid 682 that is not ejected from nozzles 306 flows from pressure chamber 412 through channel fluid passages 521 to manifold 511 .

[0034] FIG. 7 is a perspective view of an ejection channel 402 in an exemplary embodiment. As described above, the ejection channel 402 includes a pressure chamber 412, a diaphragm 410, and a nozzle 306. The pressure chamber 412 has a length 702 (i.e., along the y-axis), a width 703 (i.e., along the x-axis), and a height 704 (i.e., along the z-axis). The ejection channel 402 also includes channel fluid passages 520-521. Generally, the primary flow of printing fluid flows longitudinally or lengthwise through the ejection channel 402 along the y-axis. In an embodiment of the flow direction 714, the printing fluid flows through the channel fluid passage 520 to one side 710 (i.e., a first side) of the pressure chamber 412. The printing fluid (i.e., non-ejected printing fluid) exits the opposite side 711 (i.e., a second side) of the pressure chamber 412 through the channel fluid passage 521. Thus, printing fluid flows into and out of the pressure chamber 412 via the channel fluid passages 520 and 521 in the same lengthwise direction of the ejection channel 402 (i.e., along the y-axis). Furthermore, the first side 710 of the pressure chamber 412 is located closer to the longitudinal sides 312-313 of the print head 104 than the second side 711, which is located closer to the mid-region 550 of the print head 104 than the first side 710 (see FIG. 6A). In this configuration, the channel fluid passages 520 and 521 are located on either side 710-711 of the pressure chamber 412 in the lengthwise direction. For example, the channel fluid passages 520 and 521 are located on either side 710-711 of the pressure chamber 412 relative to the nozzle 306. It is again noted that in other embodiments, the flow direction 714 may be reversed.

[0035] The ejection channels 402 shown in Figures 4, 6A-6B, and 7 are examples to illustrate basic structures of ejection channels, such as diaphragms, pressure chambers, nozzles, and channel fluid passages. Other types of ejection channels are also contemplated herein. For example, some ejection channels may have pressure chambers with different shapes than those shown in Figures 4, 6A-6B, and 7, some ejection channels may have channel fluid passages 521 with different shapes than those shown in Figures 6A-6B, and 7, etc.

[0036] FIG. 8 shows an exploded perspective view of the head member 202 of the printhead 104 in an exemplary embodiment. In this embodiment, the head member 202 is an assembly including a housing 230 and a plate stack 232. The plate stack 232 is secured or otherwise attached to a mating surface 880 of the housing 230 to form an array of ejection channels 402. The housing 230 is an elongated member made of a rigid material, such as stainless steel. The housing 230 has a length, a width, and a height, the dimensions of the housing 230 being such that the length is greater than the width. The direction of the array of ejection channels 402 corresponds to the length of the housing 230. The housing 230 includes an access hole 234 at or near its center that passes through from the I / O face (not visible) to the opposing mating surface 880. The access hole 234 provides a passageway for an actuator assembly (not shown), such as a plurality of piezoelectric actuators, to pass through and contact the diaphragm 410 of the ejection channels 402. The mating surface 880 is the surface of the housing 230 that faces the plate stack 232 and interfaces with a plate of the plate stack 232. The housing 230 also includes manifold ducts 882-883 that extend longitudinally along the length of the mating surface 880. The manifold ducts 882-883 include elongated cuts or grooves along the mating surface 880 that are configured to transport printing fluid and form at least a portion of a manifold for the printhead 104.

[0037] Plate stack 232 includes a series of plates 801-805 and 304 secured or bonded together to form a stacked plate structure. The plate stack 232 shown in Figure 8 is intended to be an example of a basic structure for a printhead. There may be additional plates in plate stack 232 not shown in Figure 8, and the configuration of the various plates may be altered as desired. Also, Figure 8 is not drawn to scale.

[0038] In one embodiment, the plate stack 232 includes the following plates: diaphragm plate 801, support plate 802, restrictor plate 803, chamber plates 804-805, and nozzle plate 304. The diaphragm plate 801 is a thin sheet of material (e.g., metal (i.e., stainless steel), plastic, etc.) that is generally rectangular in shape and substantially flat or planar. The diaphragm plate 801 includes a diaphragm 811 that includes a sheet of semi-flexible material that forms the diaphragm 410 of the ejection channels 402. The diaphragm plate 801 further includes manifold openings 812-813. The manifold openings are openings or holes that form at least a portion of a manifold for a row of ejection channels 402. A manifold opening 812 extends longitudinally along the diaphragm plate 801 between a longitudinal side 890 of the diaphragm plate 801 and the diaphragm 811 for the row of injection channels 402 and is fluidly coupled to a manifold duct 882 of the housing 230. A manifold opening 813 extends longitudinally along the diaphragm plate 801 between the other longitudinal side 891 of the diaphragm plate 801 and the diaphragm 811 for the other row of injection channels 402 and is fluidly coupled to a manifold duct 883 of the housing 230.

[0039] The support plate 802 (also referred to as a spacer plate) is a thin sheet of material (e.g., metal (i.e., stainless steel), plastic, etc.) that is generally rectangular in shape and substantially flat or planar. The support plate 802 includes manifold openings 822-823, chamber openings 824-825, and manifold openings 826-827. The chamber openings 824 include openings or holes that are generally aligned longitudinally in a linear row 828 and configured to form at least a portion of the pressure chambers 412 in the first row 501 of the injection channels 402. The manifold openings 822 are elongated openings that extend longitudinally along the support plate 802 between a longitudinal side 892 of the support plate 802 and the chamber openings 824 in the linear row 828, and generally parallel to the linear row 828 of the chamber openings 824. The manifold openings 826 are elongated openings that extend longitudinally along the support plate 802 between the linear row 828 of chamber openings 824 and the longitudinal centerline 821 of the support plate 802 and generally parallel to the linear row 828 of chamber openings 824. The chamber openings 825 are generally longitudinally aligned with the linear row 829 and include openings or holes configured to form at least a portion of the pressure chambers 412 for the second (adjacent) row 502 of the injection channels 402. The manifold openings 823 are elongated openings that extend longitudinally along the support plate 802 between the other longitudinal side 893 of the support plate 802 and the chamber openings 825 of the linear row 829 and generally parallel to the linear row 829 of chamber openings 825. The manifold openings 827 are elongated openings that extend longitudinally along the support plate 802 between the linear row 829 of chamber openings 825 and the longitudinal centerline 821 of the support plate 802, and generally parallel to the linear row 829 of chamber openings 825.

[0040] The restrictor plate 803 is a thin sheet of material (e.g., metal (i.e., stainless steel), plastic, etc.) that is generally rectangular in shape and substantially flat or planar. The restrictor plate 803 includes restrictor openings 834-835 and channel connector openings 836-837. The restrictor openings 834 are each laterally oriented elongated openings or holes that are generally aligned longitudinally in linear rows 832. The restrictor openings 834 are configured to fluidly couple the pressure chambers 412 of the first row 501 of injection channels 402 with the manifold (i.e., formed by manifold openings 822, manifold openings 812, etc.). The restrictor openings 834 at least partially define the restrictors (or channel fluid passages 520) for the individual injection channels 402 of the first row 501. Thus, the restrictor openings 834 are each configured to fluidly couple a respective one of the pressure chambers 412 of the ejection channels 402 of the first row 501 with the manifold (e.g., manifold 510). The channel connector openings 836 include openings or holes generally aligned in a linear row 870 parallel to the linear row 832 of the restrictor openings 834. The channel connector openings 836 are disposed between the restrictor openings 834 and the longitudinal centerline 831 of the restrictor plate 803. The channel connector openings 836 are configured to fluidly couple the pressure chambers 412 of the ejection channels 402 of the first row 501 with the manifold (i.e., formed by the manifold openings 826). The restrictor openings 835 are each elongated openings or holes oriented laterally and generally aligned longitudinally with the linear row 833. The restrictor openings 835 are configured to fluidly couple the pressure chambers 412 of the ejection channels 402 of the second row 502 with the manifold (i.e., formed by the manifold openings 823, the manifold openings 813, etc.). The restrictor openings 835 at least partially define restrictors for the individual ejection channels 402 of the second row 502.Thus, the restrictor openings 835 are each configured to fluidly couple a respective one of the pressure chambers 412 of the ejection channels 402 of the second row 502 with a manifold (e.g., manifold 514). The channel connector openings 837 include openings or holes that are generally aligned in a linear row 871 that is parallel to the linear row 833 of the restrictor openings 835. The channel connector openings 837 are disposed between the restrictor openings 835 and the longitudinal centerline 831 of the restrictor plate 803. The channel connector openings 837 are configured to fluidly couple the pressure chambers 412 of the ejection channels 402 of the second row 502 with a manifold (i.e., formed by the manifold openings 827). The restrictor plate 803 further includes inter-manifold openings 838-839. Inter-manifold openings 838 are each laterally oriented elongated openings or holes that at least partially form inter-manifold fluid passages 512 configured to fluidly couple the two manifolds. Inter-manifold openings 839 are each laterally oriented elongated openings or holes that at least partially form inter-manifold fluid passages 516 configured to fluidly couple the two manifolds.

[0041] The chamber plate 804 is a thin sheet of material (e.g., metal (i.e., stainless steel), plastic, etc.) that is generally rectangular in shape and substantially flat or planar. The chamber plate 804 includes chamber openings 844-845 and channel connector openings 846-847. The chamber openings 844 are apertures or holes generally aligned longitudinally in a linear row 842 that form at least a portion of the pressure chambers 412 of the first row 501 of ejection channels 402. The channel connector openings 846 include apertures or holes generally aligned in a linear row 872 that is parallel to the linear row 842 of the chamber openings 844. The channel connector openings 846 are disposed between the chamber openings 844 and a longitudinal centerline 841 of the chamber plate 804. The channel connector openings 846 are each configured to fluidly couple the individual pressure chambers 412 of the ejection channels 402 of the first row 501 with the manifold (i.e., formed by the manifold openings 826), thus at least partially forming the channel fluid passages 521. The chamber openings 845 are apertures or holes generally aligned longitudinally in a linear row 843 and form at least a portion of the pressure chambers 412 of the ejection channels 402 of the second row 502. The channel connector openings 847 include apertures or holes generally aligned in a linear row 873 parallel to the linear row 843 of the chamber openings 845. The channel connector openings 847 are disposed between the chamber openings 845 and the longitudinal centerline 841 of the chamber plate 804. The channel connector openings 847 are each configured to fluidly couple an individual pressure chamber 412 of the ejection channels 402 in the second row 502 with the manifold (i.e., formed by the manifold openings 827), thus at least partially forming the channel fluid passages 521. The chamber plate 804 further includes inter-manifold openings 848-849. The inter-manifold openings 848 are each laterally oriented elongated openings or holes and at least partially form the inter-manifold fluid passages 512 configured to fluidly couple the two manifolds.The inter-manifold openings 849 are each laterally oriented elongated openings or holes that at least partially form the inter-manifold fluid passages 516 configured to fluidly couple the two manifolds.

[0042] The chamber plate 805 is a thin sheet of material (e.g., metal (i.e., stainless steel), plastic, etc.) that is generally rectangular in shape and substantially flat or planar. The chamber plate 805 includes chamber openings 854-855 and channel connector features 856-857. The chamber openings 854 are apertures or holes generally aligned longitudinally in a linear row 852 that form at least a portion of the pressure chambers 412 of the first row 501 of ejection channels 402. The channel connector features 856 include apertures, holes, etches, etc. generally aligned in a linear row 874 that is parallel to the linear row 852 of the chamber openings 854. The channel connector features 856 are disposed between the chamber openings 854 and a longitudinal centerline 851 of the chamber plate 805. The channel connector features 856 are each configured to fluidly couple the individual pressure chambers 412 of the ejection channels 402 of the first row 501 with the manifold (i.e., formed by the manifold openings 826), thus at least partially forming the channel fluid passages 521. The chamber openings 855 are apertures or holes generally aligned longitudinally in a linear row 853, and form at least a portion of the pressure chambers 412 of the ejection channels 402 of the second row 502. The channel connector features 857 include apertures, holes, etchings, etc. generally aligned in a linear row 875 parallel to the linear row 853 of the chamber openings 855. The channel connector features 857 are disposed between the chamber openings 855 and the longitudinal centerline 851 of the chamber plate 805. The channel connector features 857 are each configured to fluidly couple an individual pressure chamber 412 of the ejection channels 402 of the second row 502 with the manifold (i.e., formed by the manifold openings 827), thus at least partially forming the channel fluid passages 521. The channel connector features 856-857 may include holes, partial etchings, etc., and are therefore generally referred to as "features."

[0043] The nozzle plate 304 is a thin sheet of material (e.g., metal (i.e., stainless steel), plastic, etc.) that is generally rectangular in shape and substantially flat or planar. The nozzle plate 304 includes openings or nozzle holes 860 that form the nozzles 306 of the injection channels 402. For example, the nozzle holes 860 may be generally aligned longitudinally in a linear row 862 to form the nozzles 306 of the first row 501 of injection channels 402, or may be generally aligned longitudinally in a linear row 863 to form the nozzles 306 of the second row 502 of injection channels 402. One technical advantage of the plate stack 232 is that flow-through type injection channels may be formed with a reduced number of plates.

[0044] In one embodiment, one or both of the chamber plates 804-805 may be etched or otherwise patterned to form the channel fluid passages 521. FIG. 9 illustrates the chamber plate 804 in an exemplary embodiment. As described above, the chamber plate 804 is a substantially flat or planar sheet of material and thus has opposing planar surfaces 910-911. Planar surface 910 faces the ejection surface 220 of the printhead 104 and planar surface 911 faces the housing 230. The zoom window 900 shows a close-up view of the chamber opening 844 and the channel connector opening 846 of the chamber plate 804. The chamber opening 844 is an elongated opening etched or cut into the chamber plate 804 and the channel connector opening 846 is an opening etched or cut into the chamber plate 804 between the chamber opening 844 and the longitudinal centerline 841 of the chamber plate 804. In one embodiment, the chamber plate 804 further includes a partially etched segment 902 that extends from the chamber opening 844 partway toward the channel connector opening 846. To form the partially etched segment 902, the chamber plate 804 is partially etched from the plane 910 to an etch depth that is less than the thickness of the chamber plate 804. For example, the partially etched segment 902 may include a "half etch" in which the etch depth is about half the thickness of the chamber plate 804. Thus, the partially etched segment 902 does not form a hole through the chamber plate 804. The partially etched segment 902 begins at the chamber opening 844 and extends along a length 920 (i.e., along the y-axis) toward the channel connector opening 846. In one embodiment, the length 920 of the partially etched segment 902 is less than the distance 930 between the chamber opening 844 and the channel connector opening 846. A width 922 (i.e., along the x-axis) of the partially etched segment 902 may correspond to a width 932 of the chamber opening 844.Partially etched segments 902 may be etched in a similar manner between each chamber opening 844-845 and channel connector openings 846-847 of the chamber plate 804. One technical advantage is that the channel fluid passages 521 may be patterned using existing lithography processes.

[0045] FIG. 10 illustrates a chamber plate 805 in an exemplary embodiment. As described above, the chamber plate 805 is a substantially flat or planar sheet of material and thus has opposing planar surfaces 1010-1011. Planar surface 1010 faces the ejection surface 220 of the print head 104 and planar surface 1011 faces the housing 230. A zoom window 1000 illustrates a close-up view of the chamber opening 854 and the channel connector feature 856 of the chamber plate 805. The chamber opening 854 is an opening etched or cut into the chamber plate 805. In one embodiment, the channel connector feature 856 includes a partially etched segment 1002 in the chamber plate 805. To form the partially etched segment 1002, the chamber plate 805 is partially etched from the planar surface 1011 to an etch depth that is less than the thickness of the chamber plate 805. For example, the partially etched segment 1002 may include a "half etch" in which the etch depth is about half the thickness of the chamber plate 805. Thus, the partially etched segments 1002 do not form holes through the chamber plate 805. The partially etched segments 1002 extend along a length 1020 between the longitudinal centerline 851 and the chamber opening 854 of the chamber plate 805 (i.e., along the y-axis). Each of the channel connector features 856 of the chamber plate 805 may include a partially etched segment 1002 as described above. In other embodiments, the channel connector features 856 may include holes, holes and partially etched segments, etc. One technical advantage is that the channel fluid passages 521 may be patterned using existing lithography processes.

[0046] The configuration of plate stack 232 in FIGS. 8-10 is provided as an example and other configurations are contemplated herein.

[0047] FIG. 11 is a cross-sectional view of a portion of a printhead 104 in an exemplary embodiment having a plate stack 232 as in FIGS. 8-10. FIG. 11 shows a cross-section of the printhead 104 along section 6-6 of FIG. 3 to show the row 501 of ejection channels 402. The printhead 104 includes a housing 230 and a plate stack 232 secured or otherwise attached to the housing 230 to form the ejection channels 402. As described above, the plate stack 232 includes a diaphragm plate 801, a support plate 802, a restrictor plate 803, a chamber plate 804-805, and a nozzle plate 304. Nozzle holes 860 in the nozzle plate 304 define the nozzles 306 of the ejection channels 402 (see also FIG. 8). The chamber openings 854 in the chamber plate 805, the chamber openings 844 in the chamber plate 804, the restrictor openings 834 in the restrictor plate 803, and the chamber openings 824 in the support plate 802 form or define the pressure chambers 412 of the ejection channels 402. The restrictor openings 834 together with the chamber plate 804 and the support plate 802 form or define the restrictors 1110 including the channel fluid passages 520 configured to control or regulate the flow of printing fluid between the manifold 510 and the pressure chambers 412. The manifold openings 812 and 822 in the diaphragm plate 801 and the support plate 802 together with the manifold duct 882 in the housing 230 form or define the manifold 510. 11, the manifold openings 813 and 823 in the diaphragm plate 801 and the support plate 802, together with the manifold duct 883 in the housing 230, form or define the manifold 514 as shown in Figures 6A and 8. The manifold opening 826 in the support plate 802 defines the manifold 511. The channel connector openings 836 in the restrictor plate 803, the channel connector openings 846 in the chamber plate 805, and the channel connector features 856 in the chamber plate 804 form or define the channel fluid passages 521 between the pressure chambers 412 and the manifold 511.Although not shown in Figure 11, manifold openings 827 in support plate 802 define manifold 515 as shown in Figures 6A and 8. Channel connector openings 837 in restrictor plate 803, channel connector openings 847 in chamber plate 804, and channel connector features 857 in chamber plate 805 form or define channel fluid passages 521 between pressure chambers 412 and manifold 515 as shown in Figures 6A and 8. In one embodiment, manifold 511 and manifold 515 are formed by support plate 802. In one embodiment, manifold 510 and manifold 514 are at least formed by support plate 802.

[0048] One technical advantage of the printhead 104 structure disclosed above is that by directing non-jetted printing fluid toward the center of the printhead 104, printing fluid may be circulated through the ejecting channels 402, which avoids drying or accumulation of printing fluid in the ejecting channels 402. Another advantage is that the channel fluid passages 521 located toward the center of the printhead 104 are shorter conduits than other designs, resulting in less fluid resistance and faster outflow (i.e., faster circulation time) of non-jetted printing fluid from the ejecting channels 402. This design also allows for fewer plates in the plate stack 232, which reduces manufacturing costs and allows for higher frequency ejection.

[0049] 12 is a flow chart illustrating a method 1200 of operating a print head 104 in an example embodiment. The steps of method 1200 are described with reference to the print head 104 of FIG. 5A, however, one skilled in the art will recognize that method 1200 may be performed by other print heads. Additionally, the steps of the flow charts described herein are not all inclusive and may include other steps not shown, and steps may be performed in an alternative order.

[0050] In method 1200, it is assumed that the printhead 104 includes a column 501 of ejection channels 402 fluidly coupled to manifolds 510-511 disposed on either side of the column 501. For each ejection channel 402 in the column 501 (or a subset of the ejection channels 402 in the column 501), printing fluid is transported from the manifold 510 (i.e., the first manifold) to a pressure chamber 412 through an individual channel fluid passage 520 etc. for that ejection channel 402 (step 1202). Non-ejected printing fluid is transported from the pressure chamber 412 to the manifold 511 (i.e., the second manifold) through an individual channel fluid passage 521 etc. for that ejection channel 402 (step 1204).

[0051] In step 1204, non-jetted printing fluid may flow out of pressure chamber 412 toward manifold 511 in the same direction (i.e., along the y-axis) that printing fluid flowed from manifold 510 into pressure chamber 412. In FIG. 7, for example, printing fluid flows into pressure chamber 412 in the direction indicated by the arrows (i.e., from left to right), and non-jetted printing fluid flows out of pressure chamber 412 in the same direction. Thus, printing fluid may flow into and out of pressure chamber 412 via channel fluid passage 520 and channel fluid passage 521 along the same length of ejection channel 402 (i.e., along the y-axis). Also, for step 1204, as shown in FIG. 7, printing fluid may flow into one side 710 (i.e., first side) of pressure chamber 412 through channel fluid passage 521 and flow out the other side 711 (i.e., second side) of pressure chamber 412 through channel fluid passage 520. One technical advantage of transporting printing fluid in and out of the pressure chambers 412 from both sides of the column 501 is that the non-jetted printing fluid does not need to be rerouted in the opposite direction (i.e., along the y-axis), resulting in less fluid resistance and faster outflow (i.e., faster circulation time) of the non-jetted printing fluid from the ejection channels 402.

[0052] In printheads such as the printhead 104 disclosed above, nozzle failures can occur due to a variety of factors such as drying of the printing fluid at the nozzle or meniscus, deposition of the printing fluid, air bubbles present in the printing fluid, etc. These and other nozzle failures can result in degraded print quality. Therefore, it can be beneficial to mix or agitate the printing fluid within the individual ejecting channels 402.

[0053] [In-channel passive mixer] In one embodiment, one or more in-channel passive mixers may be implemented in the ejection channel 402. FIG. 13 is a perspective view of an ejection channel 402 having one or more in-channel passive mixers 1302 in an example embodiment. The diaphragm 410 is removed in FIG. 13. Generally, the printing fluid flows longitudinally or lengthwise along the ejection channel 402 (i.e., along the y-axis). Each ejection channel 402 has a length 1350 along the y-axis, and the printing fluid flows along the length 1350 of the ejection channel 402 in what is commonly referred to as a longitudinal flow. In one embodiment, for example, along the flow direction 714, the printing fluid flows through the channel fluid passage 520 (e.g., from the manifold 510) to the pressure chamber 412. The printing fluid also flows along the pressure chamber 412 where the printing fluid is ejected from the nozzle 306 or circulated through the channel fluid passage 521. Thus, the channel fluid passage 520 and the pressure chamber 412 may each include a longitudinal flow path 1310 for the printing fluid along the length 1350 of the ejection channel 402 .

[0054] Each ejection channel 402 includes vertical sidewalls along the z-axis. The vertical sidewalls of the ejection channels 402 are generally perpendicular or transverse to the plane 1354 of the ejection face 220 of the printhead 104. Printing fluid ejects from the nozzles 306 of the ejection channels 402 generally along the z-axis, and the vertical sidewalls of the ejection channels 402 are parallel to the ejection direction of the ejection channels 402. For example, the channel fluid passage 520 of the ejection channel 402 includes opposing vertical sidewalls 1322-1323, and the pressure chamber 412 includes opposing vertical sidewalls 1324-1325. In one embodiment, one or more intra-channel passive mixers 1302 may be disposed in the ejection channels 402. The intra-channel passive mixer 1302 comprises a ridge, protrusion, rib, or other structural element within the ejection channel that protrudes or projects from the vertical sidewalls of the ejection channel into the longitudinal flow path 1310 of the printing fluid (e.g., horizontally along the x-axis) along the length 1350 of the ejection channel. The intra-channel passive mixer 1302 thus protrudes across the width 1352 of the ejection channel 402.

[0055] In one embodiment, one or more intra-channel passive mixers 1302 may be disposed in the channel fluid passage 520 (e.g., in the restrictor 1110). Thus, the one or more intra-channel passive mixers 1302 may protrude from the vertical sidewalls 1322-1323 of the channel fluid passage 520. One technical advantage of implementing the intra-channel passive mixers 1302 in the channel fluid passage 520 is that the printing fluids are mixed before entering the pressure chamber 412. In one embodiment, one or more intra-channel passive mixers 1302 may be disposed in the pressure chamber 412. Thus, the one or more intra-channel passive mixers 1302 may protrude from the vertical sidewalls 1324-1325 of the pressure chamber 412. One technical advantage of implementing the intra-channel passive mixers 1302 in the pressure chamber 412 is that the printing fluids are mixed within the pressure chamber 412. In one embodiment, the intra-channel passive mixer 1302 may be disposed in the channel fluid passage 520 and pressure chamber 412 as shown in Figure 13. Although the injection channel 402 may include multiple vertical sidewalls, the intra-channel passive mixer 1302 may protrude from a vertical sidewall that is generally parallel to the length 1350 of the injection channel 402 (i.e., along the y-axis) and generally perpendicular to or transverse to the width 1352 of the injection channel 402 (i.e., along the x-axis) as shown in Figure 13. The other injection channels 402 may have a similar configuration to the intra-channel passive mixer 1302 as shown in Figure 13.

[0056] 14A-14H are plan views of an intra-channel passive mixer 1302 of an injection channel 402 in an exemplary embodiment. FIG. 14A is a plan view of a channel fluid passage 520 having multiple intra-channel passive mixers 1302. The channel fluid passage 520 has a width 1410 along the x-axis, and each intra-channel passive mixer 1302 extends or protrudes a distance 1412 inwardly from a sidewall 1322-1323 of the channel fluid passage 520. The distance 1412 that the intra-channel passive mixers 1302 protrude inwardly in the x-direction from the sidewall 1322-1323 may be in a range of about 30-70 micrometers, about 10-60% of the width 1410 of the channel fluid passage 520, etc. The length of the intra-channel passive mixers 1302 may be about 10-50 micrometers in the y-direction. Each intra-channel passive mixer 1302 may protrude approximately the same distance 1412, or the distance 1412 may vary from intra-channel passive mixer 1302 to intra-channel passive mixer 1302. FIG. 14B is a plan view of the channel fluid passage 520 showing the longitudinal flow 1418 (indicated by the arrows) of the printing fluid. In a typical printhead, the flow of the printing fluid along the ejection channels is laminar (or streamlined). Laminar flow is a type of fluid flow in which the fluid moves in a smooth or regular path. As the printing fluid flows along the channel fluid passage 520 (i.e., from left to right in FIG. 14B) and encounters the intra-channel passive mixer 1302, the intra-channel passive mixer 1302 creates turbulence 1420 in the printing fluid (i.e., localized turbulence adjacent to the intra-channel passive mixer 1302). The intra-channel passive mixer 1302 represents an obstruction in the channel fluid passage 520 that creates turbulence 1420 where the printing fluid undergoes random fluctuations and mixing. One technical advantage is that the printing fluid is mixed in the channel fluid passage 520 via the intra-channel passive mixer 1302 to restore homogeneity of the printing fluid.

[0057] In one embodiment, the pair 1440 of intra-channel passive mixers 1302 may be disposed on opposing sidewalls 1322-1323 of the channel fluid passage 520 that are generally aligned across the width 1410 of the channel fluid passage 520, as shown in FIG. 14A. In one embodiment, the pair 1440 of intra-channel passive mixers 1302 may be disposed on opposing sidewalls 1322-1323 and may be offset or staggered relative to one another across the width 1410 of the channel fluid passage 520, as shown in FIG. 14C. The intra-channel passive mixers 1302 in FIGS. 14A-14C are shown with a generally square or rectangular shape 1430. However, in other embodiments, the intra-channel passive mixers 1302 may have other shapes. For example, the intra-channel passive mixers 1302 may have a generally triangular shape 1431, as shown in FIGS. 14D-14E. The intra-channel passive mixers 1302 may have a generally shark fin shape 1432, as shown in FIG. 14F. The intra-channel passive mixers 1302 may have a generally trapezoidal shape 1433, as shown in FIG. 14G. The intra-channel passive mixers 1302 may have a generally rounded shape 1434, as shown in FIG. 14H. Any combination of different shapes may be implemented. Also, while four intra-channel passive mixers 1302 are shown in FIG. 14A-14H, the number of intra-channel passive mixers 1302 may vary as needed. For example, the number of intra-channel passive mixers 1302 and their location may depend on the turbulence length scale. For low viscosity printing fluids, fewer intra-channel passive mixers 1302 may be needed. For higher viscosity printing fluids, more intra-channel passive mixers 1302 may be needed. 14A-14H, the intra-channel passive mixer 1302 is shown within the channel fluid passage 520, similar concepts apply when the intra-channel passive mixer 1302 is located in the pressure chamber 412 of the ejection channel 402. This is not shown for simplicity. Each shape or combination of shapes of the intra-channel passive mixer 1302 provides technical advantages in generating turbulence in the printing fluid flow to cause mixing of the printing fluid.Also, different shapes may be suited to different ink types, for example, highly pigmented inks may be better suited to the shark fin shape 1430 than the square or rectangular shape 1432 in combination with the ink viscosity and surface tension to avoid pigment buildup in dead spots.

[0058] To implement an intra-channel passive mixer 1302 in the channel fluid passage 520, a restrictor plate 803 as disclosed above (see FIG. 8) may be etched or patterned with one or more intra-channel passive mixers 1302. FIG. 15 shows the restrictor plate 803 in an exemplary embodiment. A zoom window 1500 shows a close-up view of a restrictor opening 834 on the restrictor plate 803. The restrictor opening 834 is an elongated opening etched or cut into the restrictor plate 803 and has opposing vertical sidewalls 1506-1507. In one embodiment, the restrictor opening 834 is etched or patterned with one or more intra-channel passive mixers 1302 that project inwardly from the restrictor plate 803 into the restrictor opening 834. For example, the restrictor opening 834 is etched such that the intra-channel passive mixer 1302 protrudes from the sidewalls 1506-1507 toward a mid-region of the restrictor opening 834. The restrictor region 1510 of the restrictor opening 834 represents where the restrictor 1110 of the injection channel 402 is located. Thus, the intra-channel passive mixer 1302 may be etched or patterned in the restrictor region 1510 such that the intra-channel passive mixer 1302 is located in the restrictor 1110 of the injection channel 402 (e.g., in the channel fluid passage 520). Each of the restrictor openings 834-835 on the restrictor plate 803 may be patterned similarly. One technical advantage is that the intra-channel passive mixer 1302 may be patterned using existing lithography processes.

[0059] To implement the intra-channel passive mixers 1302 in the pressure chamber 4120, the chamber plate 804 (see FIG. 8) as disclosed above may be etched or patterned with one or more intra-channel passive mixers 1302. FIG. 16 shows the chamber plate 804 in an exemplary embodiment. A zoom window 1600 shows a close-up view of a chamber opening 844 in the chamber plate 804. The chamber opening 844 is an elongated opening etched or cut into the chamber plate 804 and has opposing vertical sidewalls 1606-1607. In one embodiment, the chamber opening 844 is etched or patterned with one or more intra-channel passive mixers 1302 that project inwardly from the chamber plate 804 into the chamber opening 844. For example, the chamber opening 844 is etched such that the intra-channel passive mixers 1302 project from the sidewalls 1606-1607 toward a mid-region of the chamber opening 844. Each chamber opening 844-845 on the chamber plate 804 may be similarly patterned. Also, the chamber plate 805 of the plate stack 232 may be similarly etched, or may be etched instead of etching the chamber plate 804. One technical advantage is that the intra-channel passive mixers 1302 may be patterned using existing lithography processes.

[0060] FIG. 17 is a flow chart illustrating a method 1700 of operating a print head 104 having one or more in-channel passive mixers 1302 in an exemplary embodiment. The steps of the method 1700 are described with reference to a print head 104 having ejection channels 402 as in FIG. 13, but one skilled in the art will recognize that the method 1700 may be performed by other print heads. For each ejection channel 402, a flow of printing fluid is conveyed along a longitudinal flow path 1310 of the ejection channel 402 (step 1702). One or more in-channel passive mixers 1302 impede the flow of printing fluid along the longitudinal flow path 1310 (step 1704). For example, when printing fluid flows through a channel fluid passage 520 into a pressure chamber 412 (see FIG. 13), the one or more in-channel passive mixers 1302 may impede the flow of printing fluid through the channel fluid passage 520. As the printing fluid flows through the pressure chamber 412, one or more intra-channel passive mixers 1302 may impede the flow of the printing fluid through the pressure chamber 412. One technical advantage is that the printing fluid is mixed within the ejection channels 402 to restore homogeneity of the printing fluid.

[0061] [Active mixer in chamber] In one embodiment, one or more in-chamber active mixers may be implemented in the ejection channel 402. FIG. 18 is a perspective view of an ejection channel 402 having one or more in-chamber active mixers 1802 in an exemplary embodiment. The diaphragm 410 is removed in FIG. 18. As described above, each pressure chamber 412 includes a vertical sidewall along the z-axis. In one embodiment, one or more in-chamber active mixers 1802 may be disposed in the pressure chamber 412. The in-chamber active mixer 1802 includes a structural element in the pressure chamber 412 of the ejection channel 402 configured to oscillate, vibrate, or otherwise move in response to fluid vibrations in the pressure chamber 412. Other ejection channels 402 may have a similar configuration to the in-chamber active mixer 1802 as shown in FIG. One technical advantage of implementing the in-chamber active mixer 1802 is that the printing fluid is mixed in the pressure chamber 412 to restore the homogeneity of the printing fluid.

[0062] 19 is a perspective view of an exemplary embodiment of an intra-chamber active mixer 1802. The intra-chamber active mixer 1802 includes a cantilever 1902 that includes a structural member that protrudes or projects from a vertical sidewall of the pressure chamber 412. One end 1904 of the cantilever 1902 (i.e., the connected end) is rigidly connected or attached to the vertical sidewall 1822, and the other end 1906 of the cantilever 1902 (i.e., the free end) is not attached to the pressure chamber 412 and is free to move. The cantilever 1902 has a length 1950, a width 1952, and a thickness 1954 or height. The dimensions of the cantilever 1902 may vary as desired, but the length 1950 of the cantilever 1902 may be in the range of approximately 200-260 micrometers, the width 1952 of the cantilever 1902 may be in the range of approximately 25-35 micrometers, and the thickness 1954 of the cantilever 1902 may be in the range of approximately 15-60 micrometers.

[0063] 20 is a perspective view of an intra-chamber active mixer 1802 in another exemplary embodiment. Similar to FIG. 19, the intra-chamber active mixer 1802 includes a cantilever 1902 that includes a structural member that protrudes or projects from the vertical sidewall of the pressure chamber 412. One end 1904 (i.e., the connected end) of the cantilever 1902 is rigidly connected or attached to the vertical sidewall 1822, and the other end 1906 (i.e., the free end) of the cantilever 1902 is not attached to the pressure chamber 412 and is free to move. In this embodiment, the intra-chamber active mixer 1802 further includes an end mass 2008 at the free end 1906 of the cantilever 1902.

[0064] The free end 1906 of the cantilever 1902 is free to oscillate, vibrate, or otherwise move in response to fluid vibrations in the pressure chamber 412. For example, when the actuator 416 fires in response to an ejection pulse, a pressure wave is generated in the pressure chamber 412, which causes a droplet to be ejected from the corresponding nozzle 306. The pressure waves in the printing fluid drive the free end 1906 of the cantilever 1902 to oscillate or vibrate. In other words, the in-chamber active mixer 1802 is driven (e.g., solely) from the energy of the pressure wave, which has a technical advantage in that a separate actuator or driving mechanism is not required to cause the vibration of the free end 1906 of the cantilever 1902. The vibration of the cantilever 1902 generates localized vortices and / or turbulences in the pressure chamber 412 that mix the printing fluid in the pressure chamber 412. Thus, the cantilever 1902 forms a micro-stirrer in the pressure chamber 412. One technical advantage of implementing an in-chamber active mixer 1802 comprised of a cantilever 1902 or a cantilever 1902 with an end mass 2008 is that the printing fluid is mixed within the pressure chamber 412 to restore the homogeneity of the printing fluid. This helps prevent drying or build-up of the printing fluid within the pressure chamber 412, which can result in a partially blocked or completely blocked nozzle 306. Another technical advantage is that the jetting channel 402 can self-heal from missed jets caused by air bubbles.

[0065] The pressure waves in the pressure chamber 412 resonate or absorb at a characteristic frequency. This characteristic frequency is determined by the geometry of the pressure chamber 412 (and other structures of the ejection channel 402) and their associated fluid properties, and is referred to as the resonant frequency or Helmholtz frequency of the ejection channel 402. The intra-chamber active mixer 1802 also has a resonant frequency. For example, the resonant frequency of the intra-chamber active mixer 1802 depends on the elastic modulus (i.e., the ratio of stress to strain in the elastic range of deformation) of the material used to form the cantilever 1902 (e.g., stainless steel), the moment of inertia of the cantilever 1902 (e.g., rectangular area), the length 1950 and width 1952 of the cantilever 1902, the mass of the end mass 2008 (if implemented), etc. In one embodiment, the characteristics of the intra-chamber active mixer 1802 may be selected such that the resonant frequency of the intra-chamber active mixer 1802 differs from the Helmholtz frequency of the ejection channel 402 by a threshold amount. Thus, the length 1950 and width 1952 of the cantilever 1902, the mass of the end mass 2008 (if implemented), the shape of the cantilever 1902, etc. may be selected such that the resonant frequency of the in-chamber active mixer 1802 differs from the Helmholtz frequency of the ejection channel 402 by a threshold amount. For example, a typical Helmholtz frequency of the ejection channel 402 may be in the range of about 80-120 kHz, and the resonant frequency of the in-chamber active mixer 1802 may be selected or set to be much lower than the Helmholtz frequency, such as in the range of about 0.1-5 kHz. In one embodiment, the resonant frequency of the in-chamber active mixer 1802 is selected such that the oscillations of the cantilever 1902 are far away from the Helmholtz frequency of the ejection channel 402. One technical advantage is that due to the wide gap between the Helmholtz frequency of the injection channel 402 and the resonant frequency of the in-chamber active mixer 1802 , the oscillations of the in-chamber active mixer 1802 do not interfere with the injection of the injection channel 402 .

[0066] 21A-21I are plan views of a pressure chamber 412 having one or more in-chamber active mixers 1802 in an exemplary embodiment. In FIG. 21A, the in-chamber active mixer 1802 connects to a vertical sidewall 1822 of the pressure chamber 412. In one embodiment, the vertical sidewall 1822 is generally perpendicular or transverse to the length 1350 of the ejection channel 402 (i.e., along the y-axis) and generally parallel to the width 1352 of the ejection channel 402 (i.e., along the x-axis), as shown in FIG. 18. The in-chamber active mixer 1802 may be generally centered over or aligned with the nozzle 306 of the ejection channel 402, as shown in FIG. 21A, which provides the technical advantage of uniformly mixing the printing fluid within the pressure chamber 412. The length 1950 (see FIG. 19 ) of the cantilever 1902 may be at least as long as the distance 2160 between the vertical sidewall 1822 and the nozzle 306, so that the in-chamber active mixer 1802 overlaps vertically (i.e., along the z-axis) with the nozzle 306, as shown in FIG. 21A . In one embodiment, the length 1950 (see FIG. 19 ) of the cantilever 1902 may be less than the distance 2160 between the vertical sidewall 1822 and the nozzle 306, so that the in-chamber active mixer 1802 does not overlap vertically (i.e., along the z-axis) with the nozzle 306, as shown in FIG. 21B . In FIG. 21C , the in-chamber active mixer 1802 may be generally offset from the nozzle 306 of the erupting channel 402, which provides technical benefits of manufacturing flexibility and turbulence location for mixing variations that may be needed to avoid interference with the nozzle function.

[0067] In some embodiments, the in-chamber active mixer 1802 may be disposed on different vertical sidewalls of the pressure chamber 412. For example, in FIG. 21D, the in-chamber active mixer 1802 is generally perpendicular or transverse to the length 1350 of the injection channel 402 (i.e., along the y-axis) and generally parallel to the width 1352 of the injection channel 402 (i.e., along the x-axis), and may be connected to another vertical sidewall 2123 of the pressure chamber 412. In FIG. 21E, the in-chamber active mixer 1802 is generally parallel to the length 1350 of the injection channel 402 (i.e., along the y-axis) and generally perpendicular or transverse to the width 1352 of the injection channel 402 (i.e., along the x-axis), and may be connected to another vertical sidewall 2124 of the pressure chamber 412. In FIG. 21F, the in-chamber active mixer 1802 is generally parallel to the length 1350 of the injection channel 402 (i.e., along the y-axis) and generally perpendicular or transverse to the width 1352 of the injection channel 402 (i.e., along the x-axis), and may be connected to another vertical sidewall 2125 of the pressure chamber 412. In some embodiments, more than one in-chamber active mixer 1802 may be utilized within the pressure chamber 412. In FIG. 21G, a pair 2130 of in-chamber active mixers 1802 may be connected to opposing vertical sidewalls 1822 / 2123. In FIG. 21H, a pair 2130 of in-chamber active mixers 1802 may be connected to opposing vertical sidewalls 2124-2125. In FIG. 21I, four in-chamber active mixers 1802 may be connected to vertical sidewalls 1822 and 2123-2125. The technical advantage of each configuration in FIGS. 21A-21I is that the printing fluid is mixed within the pressure chamber 412 to restore the homogeneity of the printing fluid. A plurality of in-chamber active mixers 1802 may be implemented for different ink types (e.g., higher viscosity inks or high-additive inks).

[0068] To implement an intra-chamber active mixer 1802 within the pressure chamber 412, a chamber plate 805 (see FIG. 8) as disclosed above may be etched or patterned with one or more intra-chamber active mixers 1802. FIG. 22 shows the chamber plate 805 in an exemplary embodiment. A zoom window 2200 shows a close-up view of a chamber opening 854 on the chamber plate 805. The chamber opening 854 is an opening etched or cut into the chamber plate 805 and has sidewalls 2206-2209. In one embodiment, the chamber opening 854 is etched or patterned with one or more cantilevers 1902 of the intra-chamber active mixer 1802 that project inwardly from the chamber plate 805 into the chamber opening 854. This etching controls or defines the length 1950 and width 1952 of the cantilever 1902. In one embodiment, the cantilever 1902 may be partially etched on the chamber plate 805 to control or define the thickness 1954 (shown as a hatched pattern) of the cantilever 1902. Each chamber opening 854-855 on the chamber plate 805 may be similarly patterned. Although FIG. 22 shows one cantilever 1902 protruding from the sidewall 2206, the chamber plate 805 may be similarly etched or patterned to form one or more intra-chamber active mixers 1802, as shown in FIGS. 21A-21I. One technical advantage is that the intra-chamber active mixers 1802 may be patterned using existing lithography processes, and the dimensions of the cantilever 1902 may be precisely controlled with the etching and / or partial etching process.

[0069] FIG. 23 is a flow chart illustrating a method 2300 of operating a print head 104 having an in-chamber active mixer 1802 in an exemplary embodiment. The steps of the method 2300 are described with reference to a print head 104 having ejection channels 402 as in FIG. 18, but one skilled in the art will recognize that the method 2300 may be performed by other print heads. For each ejection channel 402, a printing fluid is received in the pressure chamber 412 of the ejection channel 402 (step 2302). The free end 1906 of the cantilever 1902 oscillates to mix the printing fluid in the pressure chamber 412 (step 2304). For example, when the actuator 416 fires in response to an ejection pulse, a pressure wave is generated in the pressure chamber 412, which ejects a droplet from the corresponding nozzle 306. The pressure wave in the printing fluid drives the free end 1906 of the cantilever 1902 to oscillate or vibrate. This acts as a micro-stirrer to agitate the printing fluid locally in the pressure chamber 412. One technical advantage is that the printing fluid is mixed within the pressure chamber 412 to restore the homogeneity of the printing fluid.

[0070] [In-channel fluid mixer] In one embodiment, one or more in-channel fluid mixers may be implemented in the ejection channel 402. FIG. 24 is a perspective view of an ejection channel 402 having an in-channel fluid mixer 2402 in an exemplary embodiment. The diaphragm 410 is removed in FIG. 24. In one embodiment, the in-channel fluid mixer 2402 is disposed in a channel fluid passage 521 that fluidly couples the pressure chamber 412 with the manifold 511. The in-channel fluid mixer 2402 includes a structural element in the ejection channel 402 configured to induce a circular rotation or motion of the printing fluid flowing between the pressure chamber 412 and the manifold 511. The circular rotation or motion of the printing fluid generates a vortex that mixes the printing fluid. As shown in FIG. 24, the ejection channel 402 (and other ejection channels 402 of the printhead 104) may include a flow-through ejection channel 540. Thus, the in-channel fluid mixer 2402 may be configured to induce a circular rotation or movement of the non-jetting printing fluid flowing from the pressure chamber 412 to the manifold through the channel fluid passage 521. However, the in-channel fluid mixer 2402 may be located at a different position in the ejecting channel 402 or may be used with non-flow-through type ejecting channels 402. One technical advantage of implementing the in-channel fluid mixer 2402 is that the printing fluid is mixed within the ejecting channel 402 to restore the homogeneity of the printing fluid. The other ejecting channels 402 may have a similar configuration to the in-channel fluid mixer 2402 as shown in FIG.

[0071] 25A-25D show an in-channel fluid mixer 2402 in an exemplary embodiment. FIG. 25A is a perspective view of the in-channel fluid mixer 2402 including an inlet / outlet segment 2510 (i.e., a first inlet / outlet segment), a cylindrical mixing chamber 2512, and another inlet / outlet segment 2514 (i.e., a second inlet / outlet segment). In one embodiment, the inlet / outlet segment 2510 is disposed on one side 2516 of the mixing chamber 2512, and the inlet / outlet segment 2514 is disposed generally on the opposite side 2517 of the mixing chamber 2512 (i.e., along the y-axis). The segments 2510 and 2514 are referred to as "inlet / outlet" or "I / O" segments because the printing fluid may flow into or out of the mixing chamber 2512 through either of the segments 2510 and 2514, depending on the direction of flow of the printing fluid through the ejection channel 402. If the flow is only in one direction, the segment 2510 may be referred to as an inlet segment and the segment 2514 may be referred to as an outlet segment. The mixing chamber 2512 is a cavity having a generally cylindrical shape 2519, and the dimensions of the mixing chamber 2512 may be a diameter 2546 in the range of about 70-90 micrometers and a height 2548 in the range of about 60-120 micrometers. FIG. 25B is a top view of the in-channel fluid mixer 2402, showing a unidirectional flow of printing fluid. The inlet / outlet segment 2510 is configured to receive a flow of printing fluid (e.g., non-jetted printing fluid from the pressure chamber 412 of the ejecting channel 402). The printing fluid flows from the inlet / outlet segment 2510 to the mixing chamber 2512. Due to the structure of the mixing chamber 2512, turbulence is created within the mixing chamber 2512. For example, the volume 2540 of the mixing chamber 2512 may be larger than the volume 2542 of the inlet / outlet segment 2510 or the inlet / outlet segment 2514 (see FIG. 25A ). Additionally, the cylindrical shape 2519 of the mixing chamber 2512 induces a circular rotation or motion of the printing fluid within the mixing chamber 2512. The circular rotation or motion of the printing fluid creates a vortex 2518 as the printing fluid rotates about the axis 2520.FIG. 25C is a perspective view of the in-channel fluid mixer 2402, further showing the vortex 2518 generated in the mixing chamber 2512 as the printing fluid rotates around the axis 2520. In FIGS. 25B-25C, the printing fluid circulating in the mixing chamber 2512 exits through the inlet / outlet segment 2514 (e.g., towards a manifold). The printing fluid exiting the mixing chamber 2512 is mixed via the turbulence generated in the mixing chamber 2512, which has the technical advantage of restoring the homogeneity of the printing fluid. When the in-channel fluid mixer 2402 is implemented in the channel fluid passage 521 as shown in FIG. 24, the printing fluid may be mixed as / before the printing fluid exits the ejection channel 402 (in the case of unidirectional flow) or may be mixed as the printing fluid enters the ejection channel 402 (in the case of reverse flow).

[0072] In one embodiment, the inlet / outlet segment 2510 may be offset (e.g., horizontally offset) from the mixing chamber 2512 to induce rotation of the printing fluid within the mixing chamber 2512, as shown in FIG. 25B. For example, a center 2530 (i.e., along the x-axis) of the inlet / outlet segment 2510 may be offset from a center 2532 of the mixing chamber 2512. At the same time, the inlet / outlet segment 2514 may be generally centered with respect to the mixing chamber 2512. For example, a center 2534 (i.e., along the x-axis) of the inlet / outlet segment 2514 may be generally aligned with the center 2532 of the mixing chamber 2512. In one embodiment, the inlet / outlet segment 2514 may be offset (e.g., horizontally offset) from the mixing chamber 2512. FIG. 25D is a top view of the in-channel fluid mixer 2402. For example, a center 2534 (i.e., along the x-axis) of the inlet / outlet segment 2514 may be offset from a center 2532 of the mixing chamber 2512. In one embodiment, the inlet / outlet segment 2510 may be vertically offset from the inlet / outlet segment 2514, as shown in FIG. 25C. For example, a center 2530 (i.e., along the y-axis) of the inlet / outlet segment 2510 may be offset from a center 2534 of the inlet / outlet segment 2514. Each of these configurations has a technical advantage in causing a circular rotation or movement of the printing fluid within the mixing chamber 2512.

[0073] The in-channel fluid mixer 2402 as described above may be referred to as a passive fluid mixer and does not include actively moving elements or features to agitate the printing fluid within the mixing chamber 2512. Mixing is performed by circular rotation or movement of the printing fluid within the mixing chamber 2512. An example of an in-channel fluid mixer 2402 is shown in Figures 25A-25D, although other configurations or designs may be contemplated herein.

[0074] In one embodiment, the chamber plate 804-805 as shown in FIG. 8 may be etched or otherwise patterned to form the intra-channel fluid mixers 2402. FIG. 26 illustrates the chamber plate 804 in an exemplary embodiment. As described above, the chamber plate 804 is a substantially flat or planar sheet of material and thus has opposing planar surfaces 910-911. Planar surface 910 faces the ejection surface 220 of the print head 104 and planar surface 911 faces the housing 230. The zoom window 2600 shows a close-up view of the chamber opening 844 and the channel connector opening 846 of the chamber plate 804. The chamber opening 844 is an elongated opening etched or cut into the chamber plate 804 and the channel connector opening 846 is an opening etched or cut into the chamber plate 804 between the chamber opening 844 and the longitudinal centerline 841 of the chamber plate 804. In one embodiment, the chamber plate 804 further includes a partially etched segment 2602 that extends partway from the chamber opening 844 toward the channel connector opening 846. To form the partially etched segment 2602, the chamber plate 804 is partially etched from the plane 910 to an etch depth that is less than the thickness of the chamber plate 804. For example, the partially etched segment 2602 may include a "half etch" in which the etch depth is about half the thickness of the chamber plate 804. Thus, the partially etched segment 2602 does not form a hole through the chamber plate 804. The partially etched segment 2602 includes a rectangular segment 2602 that begins at the chamber opening 844 and extends along the length 2620 (i.e., along the y-axis) toward the channel connector opening 846. A width 2632 (i.e., along the x-axis) of the rectangular segment 2602 may correspond to the width 932 of the chamber opening 844. The partially etched segment 2602 further includes a disk-shaped or circular segment 2606 that begins at the rectangular segment 2604 and extends along a length 2622 (ie, along the y-axis) toward the channel connector opening 846 .The diameter 2626 (i.e., along the x-axis) of the circular segment 2606 is greater than the width 2632 of the rectangular segment 2604 and may be in the range of about 70-90 micrometers. The rectangular segment 2604 of the partially etched segment 2602 forms the inlet / outlet segment 2510 of the in-channel fluid mixer 2402, and the circular segment 2606 forms at least a portion of the mixing chamber 2512 of the in-channel fluid mixer 2402. The partially etched segment 2602 may be etched in a similar manner between each chamber opening 844-845 and the channel connector openings 846-847 of the chamber plate 804. One technical advantage is that the in-channel fluid mixer 2402 may be patterned using existing lithography processes.

[0075] FIG. 27 illustrates a chamber plate 805 in an exemplary embodiment. As described above, the chamber plate 805 is a substantially flat or planar sheet of material and thus has opposing planar surfaces 1010-1011. Planar surface 1010 faces the ejection surface 220 of the print head 104 and planar surface 1011 faces the housing 230. A zoom window 2700 shows a close-up view of a chamber opening 854 and a channel connector feature 856 of the chamber plate 805. The chamber opening 854 is an opening etched or cut into the chamber plate 805 and the channel connector feature 856 includes a partially etched segment 2702 etched into the chamber plate 805 between the chamber opening 854 and the longitudinal centerline 851 of the chamber plate 805. To form the partially etched segment 2702, the chamber plate 805 is partially etched from the planar surface 1011 to an etch depth that is less than the thickness of the chamber plate 805. For example, the partially etched segment 2702 may comprise a "half etch" in which the etch depth is approximately half the thickness of the chamber plate 805. Thus, the partially etched segment 1002 does not form a hole through the chamber plate 805. The partially etched segment 2702 comprises a rectangular segment 2704 that extends along a length 1020 between the longitudinal centerline 851 of the chamber plate 805 and the chamber opening 854 (i.e., along the y-axis). The partially etched segment 2702 further comprises a disk-shaped or circular segment 2706 that begins at the rectangular segment 2704 and extends along a length 2722 (i.e., along the y-axis) toward the chamber opening 854. The diameter 2726 (i.e., along the x-axis) of the circular segment 2706 is greater than the width 2732 of the rectangular segment 2704 and may be in the range of approximately 70-90 micrometers. The rectangular segment 2704 of the partially etched segment 2702 forms the inlet / outlet segment 2514 of the in-channel fluid mixer 2402 , and the circular segment 2706 forms at least a portion of the mixing chamber 2512 of the in-channel fluid mixer 2402 .A partially etched segment 2702 may be similarly etched between each chamber opening 854-855 and the channel connector features 856-857 of the chamber plate 805. One technical advantage is that the in-channel fluid mixers 2402 may be patterned using existing lithography processes.

[0076] The configuration of plate stack 232 in FIGS. 26-27 is provided as an example and other configurations are contemplated herein.

[0077] 28 is a flow chart illustrating a method 2800 of operating a print head 104 having an in-channel fluid mixer 2402 in an example embodiment. The steps of the method 2800 are described with reference to a print head 104 having ejection channels 402 as in FIG. 24, although one skilled in the art will recognize that the method 2800 may be performed by other print heads.

[0078] For method 2800, the in-channel fluid mixer 2402 receives a printing fluid (e.g., a non-jetting printing fluid) flowing between the pressure chamber 412 and the manifold through the channel fluid passage 521 (step 2802). For example, the inlet / outlet segment 2510 (see FIG. 25A) may receive a flow of printing fluid from the pressure chamber 412 of the jetting channel 402. The in-channel fluid mixer 2402 induces a circular rotation of the printing fluid (step 2804). For example, the printing fluid may flow from the inlet / outlet segment 2510 to a mixing chamber 2512, as shown in FIGS. 25B-25C. The mixing chamber 2512 induces a circular rotation or motion of the printing fluid, generating a vortex 2518 as the printing fluid rotates about an axis 2520 (optional step 2810). The printing fluid is then transported from the in-channel fluid mixer 2402 along the channel fluid passage 521 (step 2806). For example, the printing fluid circulating in the mixing chamber 2512 exits through the inlet / outlet segments 2514 (e.g., towards a manifold), as shown in Figures 25B-25C. One technical advantage is that the printing fluid is mixed within the ejection channels 402, restoring homogeneity of the printing fluid.

[0079] The above embodiments of the in-channel passive mixer 1302, the in-chamber active mixer 1802, and the in-channel fluid mixer 2402 are described with reference to a flow-through printhead 504 as shown in FIG. 5A and FIG. 6A-6B. However, one or more of the in-channel passive mixer 1302, the in-chamber active mixer 1802, and the in-channel fluid mixer 2402 may be implemented in a different flow-through printhead while retaining the above technical advantages. Furthermore, one or more of the in-channel passive mixer 1302, the in-chamber active mixer 1802, and the in-channel fluid mixer 2402 may be implemented in a non-flow-through printhead while retaining the above technical advantages. FIG. 29 is a cross-sectional view of a flow-through printhead 2904 in an exemplary embodiment. The printhead 2904 has a similar configuration as described above, with the ejection channels arranged in one or more rows. However, the flow-through ejection channels 2902 have a different configuration than described above. For example, the ejection channel 2902 includes a first channel fluid passage 2920 that fluidly couples the pressure chamber 412 to a manifold 2911 and a second channel fluid passage 2921 that fluidly couples the pressure chamber 412 to another manifold 2910. In this configuration, printing fluid may flow into and out of the pressure chamber 412 via the channel fluid passage 2920 and the channel fluid passage 2921 along a different length of the ejection channel 402 (i.e., along the y-axis) rather than in the same length direction as in FIG. 6B. For example, printing fluid may flow from the manifold 2910 to the pressure chamber 412 through the channel fluid passage 2921 (i.e., from left to right), and non-ejected printing fluid may flow in the opposite direction (i.e., from right to left) from the pressure chamber 412 to the manifold 2911 through the channel fluid passage 2920. Such a flow-through printhead 2904 may implement an in-channel passive mixer 1302, an in-chamber active mixer 1802, and / or an in-channel fluid mixer 2402, as described above.

[0080] 30 is a cross-sectional view of a non-flow-through printhead 3004 in an exemplary embodiment. The printhead 3004 has a similar configuration as described above, with the ejection channels arranged in one or more rows. However, the ejection channels are non-flow-through ejection channels 3002. For example, the ejection channels 3002 include a single-channel fluid passage 3020 that fluidly couples the pressure chambers 412 to the manifold 3010. However, there is no return path for non-ejected printing fluid to exit the pressure chambers 412. Such a non-flow-through printhead 3004 may implement the in-channel passive mixers 1302 and / or in-chamber active mixers 1802 described above, while retaining the technical advantages described above.

[0081] The following sections and / or examples relate to further embodiments or examples. Details in the examples may be used anywhere in one or more of the embodiments. Various features of different embodiments or examples may be combined in various ways, with some features included and other features excluded, to suit a variety of different applications. The examples may include subject matter such as a method, a means for performing the operations of the method, at least one machine-readable medium including instructions that, when executed by a machine, cause the machine to perform the operations of the method, or at least one machine-readable medium including instructions that cause the machine to perform the operations of the method, according to the embodiments and examples described herein.

[0082] Some embodiments related to Example 1 include a flow-through printhead including a plurality of ejecting channels arranged in first and second rows generally parallel along a length of the printhead, each of the ejecting channels including a diaphragm, a pressure chamber, and a nozzle configured to eject a printing fluid, a first manifold fluidly coupled to the ejecting channels in the first row, and a second manifold fluidly coupled to the ejecting channels in the first row, the first and second manifolds being disposed on opposite sides of the first row, and the second manifold being disposed in an intermediate region between the first and second rows.

[0083] Example 2 includes the subject matter of Example 1, wherein the first row of ejection channels each include a first channel fluid passage fluidly coupling the pressure chamber to a first manifold and a second channel fluid passage fluidly coupling the pressure chamber to a second manifold, the first channel fluid passage and the second channel fluid passage being disposed on opposite sides of the pressure chamber.

[0084] Example 3 includes the subject matter of Examples 1 and 2, where the printing fluid flows into and out of the pressure chamber via the first channel fluid passage and the second channel fluid passage along the same length of the ejection channel.

[0085] Example 4 includes the subject matter of Examples 1-3, wherein the second channel fluid passages of each of the first row of ejection channels are disposed in the intermediate region.

[0086] Example 5 includes the subject matter of Examples 1-4, wherein the first manifold is disposed in an outer region between the longitudinal sides of the flow-through printhead and the first row, and the first channel fluid passages of each of the ejection channels in the first row are disposed in the outer region.

[0087] Example 6 includes the subject matter of Examples 1-5, and further includes one or more inter-manifold fluid passages fluidly coupling the first manifold and the second manifold.

[0088] Example 7 includes the subject matter of Examples 1-6, and further includes a third manifold fluidly coupled to the second row of ejection channels and a fourth manifold fluidly coupled to the second row of ejection channels. The third manifold and the fourth manifold are disposed on opposite sides of the second row, and the fourth manifold is disposed in the middle region. The second manifold is disposed between the first row and the fourth manifold, and the fourth manifold is disposed between the second row and the second manifold.

[0089] Example 8 includes the subject matter of Examples 1-7 and further includes an injection device.

[0090] Some embodiments related to Example 9 include a flow-through printhead including a housing and a plate stack attached to the housing forming a plurality of ejection channels arranged in first and second rows generally parallel along a length of the printhead, each of the ejection channels including a diaphragm, a pressure chamber, and a nozzle configured to eject a printing fluid. The plate stack forms a first manifold arranged longitudinally and fluidly coupled to the ejection channels of the first row, and a second manifold arranged longitudinally and fluidly coupled to the ejection channels of the first row. The first and second manifolds are arranged on either side of the first row, and the second manifold is arranged in an intermediate region between the first and second rows.

[0091] Example 10 includes the subject matter of example 9, wherein the first row of ejection channels each include a first channel fluid passage fluidly coupling the pressure chamber to the first manifold and a second channel fluid passage fluidly coupling the pressure chamber to the second manifold, the first channel fluid passage and the second channel fluid passage being disposed on opposite sides of the pressure chamber.

[0092] Example 11 includes the subject matter of Examples 9 and 10, wherein the printing fluid flows into and out of the pressure chamber via the first channel fluid passage and the second channel fluid passage along the same length of the ejection channel.

[0093] Example 12 includes the subject matter of Examples 9-11, wherein the second channel fluid passages of each of the first row of ejection channels are disposed in the intermediate region.

[0094] Example 13 includes the subject matter of Examples 9-12, wherein the first manifold is disposed in an outer region between the longitudinal sides of the flow-through printhead and the first row, and the first channel fluid passages of each of the ejection channels in the first row are disposed in the outer region.

[0095] Example 14 includes the subject matter of Examples 9-13, wherein the plate stack includes a diaphragm plate forming a diaphragm of the ejection channel, a support plate, a restrictor plate, first and second chamber plates forming pressure chambers of the ejection channel, and a nozzle plate having nozzle holes defining nozzles of the ejection channel. The support plate forms a first manifold and a second manifold.

[0096] Example 15 includes the subject matter of Examples 9-14, wherein the support plate includes chamber openings generally aligned longitudinally in a linear row to form at least a portion of the pressure chambers of the first row of ejection channels, first manifold openings extending longitudinally between a longitudinal side of the support plate and the chamber openings to form at least a portion of a first manifold, and second manifold openings extending longitudinally between the linear row of chamber openings and a longitudinal centerline of the support plate to form a second manifold.

[0097] Example 16 includes the subject matter of Examples 9-15, wherein the restrictor plate includes restrictor openings generally aligned longitudinally in linear rows, each of the restrictor openings configured to fluidly couple a respective one of the pressure chambers of the first row of ejection channels with the first manifold, and the channel connector openings are generally aligned in a linear row parallel to the linear rows of the restrictor openings and disposed between the restrictor openings and a longitudinal centerline of the restrictor plate, each of the channel connector openings configured to fluidly couple a respective one of the pressure chambers of the first row of ejection channels with the second manifold.

[0098] Example 17 includes the subject matter of Examples 9-16, wherein the first chamber plate includes chamber openings generally aligned longitudinally in a linear row to form at least a portion of the pressure chambers of the first row of ejection channels, and channel connector openings generally aligned in a linear row parallel to the linear row of chamber openings and disposed between the chamber openings and a longitudinal centerline of the first chamber plate, each of the channel connector openings configured to fluidly couple a respective one of the pressure chambers of the first row of ejection channels with the second manifold.

[0099] Example 18 includes the subject matter of Examples 9-17, wherein the first chamber plate further includes a partially etched segment extending from the chamber opening partway toward the channel connector opening.

[0100] Example 19 includes the subject matter of Examples 9-18, wherein the second chamber plate includes chamber openings generally aligned longitudinally in a linear row to form at least a portion of the pressure chambers of the first row of ejection channels, and channel connector features generally aligned in a linear row parallel to the linear row of chamber openings and disposed between the chamber openings and a longitudinal centerline of the second chamber plate, each of the channel connector features configured to fluidly couple a respective one of the pressure chambers of the first row of ejection channels with the second manifold.

[0101] Example 20 includes the subject matter of Examples 9-19, wherein the channel connector mechanism includes a partially etched segment.

[0102] Example 21 includes the subject matter of Examples 9-20 and further includes an injection device.

[0103] Some embodiments related to Example 22 include a method including operating a flow-through printhead including a plurality of ejecting channels arranged in first and second rows generally parallel along a length of the printhead, each of the ejecting channels including a diaphragm, a pressure chamber, and a nozzle configured to eject a printing fluid, and including a first manifold fluidly coupled to the ejecting channels of the first row and a second manifold fluidly coupled to the ejecting channels of the first row. The first and second manifolds are disposed on opposite sides of the first row, and the second manifold is disposed in an intermediate region between the first and second rows. Operating the flow-through printhead includes, for each ejecting channel of the first row, conveying a printing fluid from the first manifold on a first side of the first row to a pressure chamber, and, for each ejecting channel of the first row, conveying a non-ejected printing fluid from the pressure chamber to a second manifold on a second side of the first row opposite the first side.

[0104] Although specific embodiments are described herein, the scope of the present invention is not limited to these specific embodiments, but is defined by the following claims and any equivalents thereof.

Claims

1. A flow-through printhead, comprising: a plurality of ejection channels arranged in first and second generally parallel rows along a length of the printhead, each of the ejection channels including a diaphragm, a pressure chamber, and a nozzle configured to eject a printing fluid; a first manifold fluidly coupled to the first row of injection channels; a second manifold fluidly coupled to the first row of injection channels; a third manifold fluidly coupled to the second row of injection channels; a fourth manifold fluidly coupled to the second row of injection channels; Including, the first manifold and the second manifold are disposed on opposite sides of the first row, and the second manifold is disposed in an intermediate region between the first row and the second row; the third manifold and the fourth manifold are disposed on opposite sides of the second row, and the fourth manifold is disposed in the intermediate region between the first row and the second row; A flow-through printhead, wherein the second manifold is fluidly isolated from the fourth manifold.

2. each of the first row of ejection channels includes a first channel fluid passage fluidly coupling the pressure chamber to the first manifold and a second channel fluid passage fluidly coupling the pressure chamber to the second manifold; 2. The flow-through printhead of claim 1, wherein the first channel fluid passage and the second channel fluid passage are disposed on opposite sides of the pressure chamber.

3. 3. The flow-through printhead of claim 2, wherein the printing fluid flows into and out of the pressure chamber via the first channel fluid passage and the second channel fluid passage in the same length direction of the ejection channel.

4. 3. The flow-through printhead of claim 2, wherein the second channel fluid passages of each of the first row of ejection channels are disposed in the intermediate region.

5. the first manifold is disposed in an outer region between a longitudinal side of the flow-through printhead and the first row; 5. The flow-through printhead of claim 4, wherein the first channel fluid passages of each of the first row of ejection channels are disposed in the outer region.

6. 10. The flow-through printhead of claim 1, further comprising one or more inter-manifold fluid passages fluidly coupling the first manifold and the second manifold.

7. A flow-through printhead as described in claim 1, wherein the second manifold is positioned between the first row and the fourth manifold, and the fourth manifold is positioned between the second row and the second manifold.

8. 13. A jetting device comprising the flow-through printhead of claim 1.

9. A flow-through printhead, comprising: Housing and a plate stack attached to the housing forming a plurality of ejection channels arranged in first and second generally parallel rows along a length of the printhead, each of the ejection channels including a diaphragm, a pressure chamber, and a nozzle configured to eject a printing fluid; Including, the plate stack is longitudinally disposed to form a first manifold fluidly coupled to the first row of injection channels; the plate stack defining a second manifold longitudinally disposed and fluidly coupled to the first row of injection channels; the plate stack defining a third manifold longitudinally disposed and fluidly coupled to the second row of injection channels; the plate stack defining a fourth manifold longitudinally disposed and fluidly coupled to the second row of injection channels; the first manifold and the second manifold are disposed on opposite sides of the first row, and the second manifold is disposed in an intermediate region between the first row and the second row; the third manifold and the fourth manifold are disposed on opposite sides of the second row, and the fourth manifold is disposed in the intermediate region between the first row and the second row; A flow-through printhead, wherein the second manifold is fluidly isolated from the fourth manifold.

10. each of the ejection channels in the first row includes a first channel fluid passage fluidly coupling the pressure chamber to the first manifold and a second channel fluid passage fluidly coupling the pressure chamber to the second manifold; 10. The flow-through printhead of claim 9, wherein the first channel fluid passage and the second channel fluid passage are disposed on opposite sides of the pressure chamber.

11. 11. The flow-through printhead of claim 10, wherein the printing fluid flows into and out of the pressure chamber via the first channel fluid passage and the second channel fluid passage in the same length direction of the ejection channel.

12. 11. The flow-through printhead of claim 10, wherein the second channel fluid passages of each of the first row of ejection channels are disposed in the intermediate region.

13. the first manifold is disposed in an outer region between a longitudinal side of the flow-through printhead and the first row; 13. The flow-through printhead of claim 12, wherein the first channel fluid passages of each of the first row of ejection channels are disposed in the outer region.

14. The plate stack comprises: a diaphragm plate forming a diaphragm of the injection channel; A support plate; A restrictor plate; a first chamber plate and a second chamber plate forming pressure chambers for the ejection channels; a nozzle plate having nozzle holes defining the nozzles of the ejection channels; Including, 11. The flow-through printhead of claim 10, wherein the support plate forms the first manifold and the second manifold.

15. The support plate is chamber openings generally aligned longitudinally in a linear row to define at least a portion of the pressure chambers of the first row of ejection channels; a first manifold opening extending longitudinally between a longitudinal side of the support plate and the chamber opening to form at least a portion of the first manifold; a second manifold opening extending longitudinally between the linear array of chamber openings and a longitudinal centerline of the support plate to form the second manifold; 15. The flow-through printhead of claim 14, comprising:

16. The restrictor plate is restrictor openings generally aligned longitudinally in a linear row, each of the restrictor openings configured to fluidly couple a respective one of the pressure chambers of the injection channels in the first row with the first manifold; channel connector openings generally aligned in a linear row parallel to the linear row of restrictor openings and disposed between the restrictor openings and a longitudinal centerline of the restrictor plate; Including, 16. The flow-through printhead of claim 15, wherein each of the channel connector openings is configured to fluidly couple a respective one of the pressure chambers of the first row of ejection channels with the second manifold.

17. The first chamber plate includes: chamber openings generally aligned longitudinally in a linear row to define at least a portion of the pressure chambers of the first row of ejection channels; channel connector openings generally aligned in a linear row parallel to the linear row of chamber openings and disposed between the chamber openings and a longitudinal centerline of the first chamber plate; Including, 16. The flow-through printhead of claim 15, wherein each of the channel connector openings is configured to fluidly couple a respective one of the pressure chambers of the first row of ejection channels with the second manifold.

18. The first chamber plate includes:

20. The flow-through printhead of claim 17, further comprising a partially etched segment extending partway from the chamber opening towards the channel connector opening.

19. The second chamber plate includes: chamber openings generally aligned longitudinally in a linear row to define at least a portion of the pressure chambers of the first row of ejection channels; a channel connector mechanism generally aligned in a linear row parallel to the linear row of chamber openings and disposed between the chamber openings and a longitudinal centerline of the second chamber plate; Including, 16. The flow-through printhead of claim 15, wherein each of the channel connector mechanisms is configured to fluidly couple a respective one of the pressure chambers of the first row of ejection channels with the second manifold.

20. 20. The flow-through printhead of claim 19, wherein the channel connector feature comprises a partially etched segment.

21. 10. An ejection device comprising the flow-through printhead of claim 9.

22. 1. A method comprising operating a flow-through printhead, comprising: The flow-through print head comprises: a plurality of ejection channels arranged in first and second generally parallel rows along a length of the printhead, each of the ejection channels including a diaphragm, a pressure chamber, and a nozzle configured to eject a printing fluid; a first manifold fluidly coupled to the first row of injection channels; a second manifold fluidly coupled to the first row of injection channels; a third manifold fluidly coupled to the second row of injection channels; a fourth manifold fluidly coupled to the second row of injection channels; Including, the first manifold and the second manifold are disposed on opposite sides of the first row, and the second manifold is disposed in an intermediate region between the first row and the second row; 、 the third manifold and the fourth manifold are disposed on opposite sides of the second row, and the fourth manifold is disposed in the intermediate region between the first row and the second row; the second manifold is fluidly isolated from the fourth manifold; The operating step includes: conveying printing fluid from the first manifold on a first side of the first row to the pressure chamber for each ejection channel of the first row; conveying, for each ejection channel of the first row, a non-ejected printing fluid from the pressure chamber to the second manifold on a second side of the first row opposite the first side; A method comprising:

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