WO2022086548A1

WO2022086548A1 - Printhead in which inter-group spacing is greater than intra-group spacing

Info

Publication number: WO2022086548A1
Application number: PCT/US2020/057004
Authority: WO
Inventors: Garrett E. CLARK; Eric Thomas MARTIN; Jacob LUM
Original assignee: Hewlett-Packard Development Company, L.P.
Priority date: 2020-10-23
Filing date: 2020-10-23
Publication date: 2022-04-28

Abstract

A fluid-ejection printhead includes channel, interposer, and fluid- ejection layers. The channel layer has supply and return channels. The interposer layer defines inlet and outlet ports respectively fluidically connected to the supply and return channels. The fluid-ejection layer includes fluid- ejection element groups that each include first and second fluid-ejection elements fluidically connected to the supply and return channels. The inter-group spacing along an axis non-perpendicular to a channel axis of the supply and return channels is greater than the intra-group spacing along the axis.

Description

PRINTHEAD IN WHICH INTER-GROUP SPACING IS GREATER THAN INTRA-GROUP SPACING FOR FLUID-EJECTION ELEMENT GROUPS

BACKGROUND

[0001] Printing devices, including industrial printing devices that are commonly referred to as presses as well as office- and home-oriented printing devices that include standalone printers and all-in-one (AIO) printing devices which combine printing functionality with other functionality like scanning and copying, can use a variety of different printing techniques. One type of printing technology is inkjet printing technology, which is more generally a type of fluid-ejection technology. A fluid-ejection device, such as a printhead (i.e. , a printhead die) or a printing device having such a printhead, includes a number of fluid-ejection elements with respective nozzles. Firing a fluidejection element causes the element to eject fluid, such as a drop thereof, from its nozzle.

BRIEF DESCRIPTION OF THE DRAWINGS

[0002] FIG. 1 A is a top-view diagram of an example fluid-ejection cartridge including a fluid-ejection printhead having non-uniformly spaced sparse fluid-ejection elements. FIGs. 1 B and 1C are cross-sectional front view diagrams of the cartridge. FIGs. 1 D and 1 E are cross-sectional side view diagrams of the cartridge.

[0003] FIG. 2 is a top-view diagram of an example fluid-ejection printhead having non-uniformly spaced sparse fluid-ejection elements.

[0004] FIG. 3 is a top-view diagram of another example fluid-ejection printhead having non-uniformly spaced sparse fluid-ejection elements. [0005] FIGs. 4 and 5 are top-view diagrams of example fluid-ejection element groups that can instead be used in the fluid-ejection printheads of FIGs. 2 and 3, respectively.

[0006] FIG. 6 is a block diagram of an example fluid-ejection device.

DETAILED DESCRIPTION

[0007] As noted in the background, a fluid-ejection printhead (i.e. , a printhead die) includes a number of fluid-ejection elements with respective nozzles from which the elements eject fluid, such as by energizing firing resistors of the elements. The fluid may form images on media such as paper, or may build three-dimensional (3D) objects in the case of 3D printing devices. As printing technology has advanced, the cooling needs for printheads have increased for a variety of different reasons. The density or number of fluidejection elements on a given printhead may be particularly great. The rate at which the elements are fired may be particularly high. The power requirements of the firing resistors may likewise be particularly high. The net effect of these and other factors is the generation of unwanted heat within a printhead, resulting in the printhead having to be cooled so as not to affect image formation quality or cause premature printhead failure.

[0008] Printing technology advancement has also resulted in printheads being used with more challenging types of fluid, such as printing fluid including ink. Fluids with greater volatility, which is the propensity of the carrier liquid of a fluid to evaporate, leaving being its solid particles, are increasingly used. Fluids that are higher in solid weight percentage, which is the percentage by weight of the solids contained within a fluid, are also used more often. Such fluids are more likely to form viscous plugs at the nozzles of fluid-ejection elements. A plug forms when fluid sufficiently dries out at the nozzle, leaving behind a greater mass of solids that clog the nozzle in the form of a plug. Clogged nozzles can deleteriously affect image quality, by impeding or preventing fluid ejection through the nozzles, and/or by affecting the amount or trajectory of fluid ejected through the nozzles.

[0009] Recirculating fluid within a printhead, even when the fluidejection elements are in standby and not actively printing, can ameliorate these issues. As to printhead cooling, a printhead may have backside channels that permit fluid to recirculate at the backside of the fluid-ejection elements. The constantly recirculating fluid absorbs and removes heat generated within the printhead, such as by the firing resistors of the fluidejection elements. The same fluid ejected from the printhead can thus provide liquid-cooling functionality.

[0010] As to challenging fluid usage, the fluid-ejection elements of a printhead may permit fluid to be recirculated through them. For example, fluid recirculation may occur through a fluid-ejection element’s chamber, which contains the fluid that is ejectable through the element’s nozzle via firing resistor energization. Such fluid recirculation reduces the likelihood of plug formation by constantly replenishing the fluid located relatively close to the nozzle of a fluid-ejection element, inhibiting the fluid from drying out at the nozzle.

[0011] Printhead architectures that permit fluid recirculation may further include sparse nozzle configurations. In a sparse nozzle printhead architecture, more of the planar area of the printhead is occupied by nozzles of the fluid-ejection elements so that there is increased space between consecutive nozzles. Sparse nozzles can provide for improved fluid-ejection aerodynamic performance. In existing sparse nozzle printhead architectures, the nozzles are generally uniformly positioned over more of the planar area of the printhead.

[0012] However, dedicating more of the planar area of the printhead for nozzles in a sparse configuration means that less space outside that occupied by the nozzles is available for fluid-ejection element control and monitoring circuitry. Such circuitry may instead have to be disposed in the spaces between nozzles. This can be beneficial: monitoring circuitry may benefit from close proximity to corresponding fluid-ejection elements, and more closely locating circuitry to corresponding elements means that conductive traces connecting the circuitry to those elements are shorter.

[0013] Nevertheless, there are drawbacks to having to locate circuitry in the spaces between nozzles in a sparse nozzle printhead architecture. Although the overall area available for fluid-ejection element control and monitoring circuitry may not decrease between non-sparse and sparse nozzle configurations, in sparse configurations the available printhead area for circuitry is not contiguous but rather divided over multiple smaller regions that are discontiguous to one another. It can be difficult to fit more complex circuitry in each of these regions.

[0014] Described herein are sparse nozzle printhead architectures in which the nozzles are non-uniform ly positioned over the planar area of the printhead. A printhead can have fluid-ejection element groups that each include first and second fluid-ejection elements that fluidical ly connect to and span supply and return channels of the printhead. The inter-group spacing along an axis non-perpendicular to a channel axis of the supply and return channels is greater than the intra-group spacing along this axis. That is, the spacing between elements of nonadjacent consecutive groups is greater than the spacing between the elements of each group.

[0015] Therefore, as compared to a uniform sparse nozzle configuration, the available printhead area for fluid-ejection element control and monitoring circuitry is divided over a smaller number of discontiguous regions that are individually larger in size. For example, rather than having a region adjacent to each fluid-ejection element for circuitry as in a uniform configuration, the described non-uniform sparse nozzles configurations may have a region adjacent to every pair of elements that is twice the size. Circuitry can thus still be located close to their corresponding elements.

[0016] FIG. 1 A shows the top-view of an example fluid-ejection cartridge 150 including a fluid-ejection printhead 100 attached to a cartridge body 160. The cartridge 150 may or may not include the fluid that the printhead 100 ejects. As one example, the cartridge 150 may also be referred to as a module used in industrial printing presses. The cartridge body 160 defines a fluidic supply slot 102S and a fluidic return slot 102R, which are collectively referred to as the fluid slots 102. The printhead 100 includes a backside supply channel 106S and a backside return channel 106R, which are collectively referred to as the backside channels 106, and which are disposed over the slots 102. The backside channels 106 extend horizontally in the example of FIG. 1A and define a channel axis, whereas the fluid slots 102 extend vertically along an axis perpendicular to the channel axis. [0017] The supply channel 106S is fluidically connected to the supply slot 102S via an inlet port 104S. The return channel 106R is fluidically connected to the return slot 102R via an outlet port 104R. The inlet port 104S and the outlet port 104R are collectively referred to as the ports 104. While the printhead 100 is depicted as including one inlet port 104S and one outlet port 104R, there may be more than one of each port 104. Similarly, while the printhead 100 is depicted as including one supply channel 106S and one return channel 106R, in another implementation there may be multiple channels 106S and multiple channels 106R.

[0018] The printhead 100 also includes fluid-ejection element groups 107. Each group 107 includes a fluid-ejection element 108-1 having a nozzle 110-1 and a fluid-ejection element 108-2 having a nozzle 110-2. The fluidejection elements 108-1 and 108-2 of the groups 107 are collectively referred to as the fluid-ejection elements 108, and the nozzles 110-1 and 110-2 are likewise collectively referred to as the nozzles 110. While the printhead 100 is depicted as including two fluid-ejection elements 108 in each group 107, in another implementation there may be more than two elements 108 in each group 107.

[0019] The fluid-ejection elements 108 are disposed over the channels 106. When the fluid-ejection elements 108 are fired, fluid is rejected from the elements 108 through their respective nozzles 110. Each fluid-ejection element 108 spans and is fluidically connected between the supply channel 106S and the return channel 106R, such as via corresponding inlet and outlet feed holes. While the printhead 100 is depicted as including eight fluidejection elements 108 organized over four groups 107, in actual implementation the printhead 100 may likely include more than eight elements

108 spanning the pair of channels 106.

[0020] The fluid-ejection elements 108 of each group 107 can be of the same or different type of fluid-ejection element. For instance, the fluidejection elements 108 of each group 107 can have different drop weights. In the depicted example, the fluid-ejection element 108-1 of each group 107 ejects fluid at a drop weight that is less than the drop weight at which the fluidejection element 108-2 of each group 107 ejects the fluid. Therefore, each nozzle 110-1 is shown as being smaller in size (e.g., smaller in diameter) than each nozzle 110-2.

[0021] The fluid-ejection printhead 100 has a fluid recirculation path through which fluid recirculates through the fluid-ejection elements 108 from the supply slot 102S to the return slot 102R. This fluid recirculation path is defined by fluid flow in the direction of arrows 116A, 116B, 116C, 116D, 116E, 116F, and 116G. Fluid flow out of the plane of FIG. 1A is indicated as an arrow point (i.e. , a circled point); fluid flow into the plane of FIG. 1A is indicated an arrow tail (i.e., a circled X or crosshatch).

[0022] The fluid recirculation path may begin with fluid entering the supply channel 106S from the supply slot 102S via the inlet port 104S per the point of arrow 116A. The fluid can flow along the length of the supply channel 106S per arrow 116B. The fluid enters the fluid-ejection elements 108 from the supply channel 106S per the points of arrows 116C. The fluid flows through the elements 108 past their nozzles 110 per arrow 116D, before exiting into the return channel 106R per the tails of arrows 116E. The fluid then flows through the return channel 106R in the direction of arrow 116F. The fluid exits the return channel 106R into the return slot 102R via the outlet port 104R per the tail of arrow 116G, completing the fluid recirculation path. [0023] FIGs. 1 B and 1 C show different cross-sectional front views of the fluid-ejection cartridge 150 at cross-sectional lines 118B and 118C in FIG.

1 A, respectively. FIG. 1 B depicts the first part of the fluid recirculation path, and FIG. 1 C depicts the last part of the fluid recirculation path. In both FIGs. 1 B and 1 C, the cartridge body 160 of the cartridge 150 defines and thus includes the fluid slots 102S, 102R, and 102B.

[0024] In both FIGs. 1 B and 1 C, the fluid-ejection printhead 100 of the cartridge 150 includes an interposer layer 1121, a channel layer 112C, and a fluid-ejection layer 112E. The interposer layer 1121 includes the inlet port 104S per FIG. 1 B, and the outlet port 104R per FIG. 1 C. The channel layer 112C includes the supply channel 106S per FIG. 1 B, and the return channel 106R per FIG. 1C. The fluid-ejection layer 112E includes the fluid-ejection element groups 107 of fluid-ejection elements 108 with their respective nozzles 110. The fluid-ejection layer 112E defines the fluid recirculation path by spanning the channels 106 of the channel layer 112C.

[0025] As depicted in FIG. 1 B, the fluid recirculation path may begin with fluid entering the supply channel 106S through the inlet port 104S per the arrow 116A, and flowing across the supply channel 106S per the arrow 116B. The fluid flows into the fluid-ejection elements 108 per the arrows 116C, and then past their nozzles 110 per the tails of arrows 116D in FIG. 1 B and the points of arrows 116D in FIG. 1 C. As depicted in FIG. 1 C, the fluid recirculation path continues with the fluid flowing into the return channel 106R from the fluid-ejection elements 108 per the arrows 116E. The fluid flows through the return channel 106R per the arrow 116F before flowing into the return slot 102R through the outlet port 104R per the arrow 116G, completing the recirculation path.

[0026] FIGs. 1 D and 1 E show different cross-sectional side views of the fluid-ejection printhead 100 and the cartridge body 160 of the fluid-ejection cartridge 150 at cross-sectional lines 118D and 118E in FIG. 1A, respectively. FIG. 1 D depicts a portion of the fluid recirculation path, and FIG. 1 E depicts the remainder of the fluid recirculation path. As in FIGs. 1 B and 1 C, the interposer layer 1121, the channel layer 112C, and the fluid-ejection layer 112E are shown in FIGs. 1 D and 1 E.

[0027] In the fluid recirculation path, as depicted in FIG. 1 D, fluid flows from the supply slot 102S through the inlet port 104S to the supply channel 106S per the arrow 116A, and across the supply channel 106S per the arrow 116B. The fluid flows into the fluid-ejection elements 108 of the fluid-ejection element groups 107 per the arrow 116C, and then past their nozzles 110 per the arrow 116D in FIGs. 1 D and 1 E. The fluid flows into the return channel 106R from the fluid-ejection elements 108 per the arrow 116E in FIGs. 1 D and 1 E, before flowing through the return channel 106R per the tail of arrow 116F in FIG. 1 D and the point of arrow 116F in FIG. 1 E. As depicted in FIG. 1 F, the fluid then flows into the return slot 102R through the outlet port 104R per the arrow 116G, completing the fluid recirculation path.

[0028] The inter-group 107 spacing along the channel axis is greater than the intra-group 107 spacing along the channel axis in FIGs. 1A-1 E, as is best seen in FIGs. 1A-1 C. The spacing between any two fluid-ejection elements 108 may be defined as the distance between the centers of their fluid nozzles 110. The inter-group 107 spacing is greater than the intra-group 107 spacing in that the spacing between corresponding fluid-ejection elements 108 of nonadjacent consecutive groups 107 is greater than the spacing between the fluid-ejection elements 108 of each group 107. That is, the spacing between the element 108-2 of a group 107 and the element 108-1 of the next group 107 is greater than the spacing between the elements 108-1 and 108-2 of either group 107. More generally, the inter-group 107 spacing along any axis non-perpendicular to the channel axis is greater than the intragroup 107 spacing along such an axis.

[0029] The spacing between the fluid-ejection elements 108-1 of nonadjacent consecutive groups 107 is uniform and greater than the spacing between the elements 108-1 and 108-2 of each group 107, and may be equal to or greater than twice the spacing between the elements 108-1 and 108-2 of each group 107. The spacing between the fluid-ejection elements 108-2 of nonadjacent consecutive groups 107 is likewise uniform and greater than the spacing between the elements 108-1 and 108-2 of each group 107, and may be equal to or greater than twice the spacing between the elements 108-1 and 108-2 of each group 107. The spacing between the elements 108-1 of nonadjacent consecutive groups 107 can be equal to the spacing between the elements 108-2 of nonadjacent consecutive groups 107.

[0030] FIG. 2 shows a top view of an example implementation of the fluid-ejection printhead 100, including the fluid-ejection layer 112E. The fluidejection element groups 107 of fluid-ejection elements 108 having respective nozzles 110 are organized in a chevron configuration in the example printhead 100. The channel axis in the example of FIG. 2 corresponds to or follows the chevron configuration of the fluid-ejection element groups 107, and thus is non-linear in that it is made up of two linear segments. In another implementation, the groups 107 of elements 108 may be organized in a different configuration, such as a linear configuration as in FIGs. 1A-1 E. The elements 108-1 and 108-2 of each group 107 are aligned with one another as depicted, but may instead be staggered, as described later in the detailed description.

[0031] The inter-group 107 spacing 202 may be defined as the distance between centers of nonadjacent consecutive fluid-ejection groups 107. The intra-group 107 spacing 204 may be defined as the distance between centers of the nozzles 110 of the fluid-ejection elements 108 of each group 107, and is less than the spacing 202. The spacing 206 between fluid-ejection elements 108-1 of nonadjacent consecutive groups 107 may be defined as the distance between the centers of their respective nozzles 110-1 , and may be equal to the spacing 202. The spacing 208 between fluid-ejection elements 108-2 of nonadjacent consecutive groups 107 may be defined as the distance between the centers of their respective nozzles 110-2, and may likewise be equal to the spacing 202.

[0032] The fluid-ejection printhead 100 includes fluid-ejection element circuitry 210 located between nonadjacent consecutive groups 107. Each fluid-ejection element circuitry 210 can be control and monitoring circuitry for controlling and monitoring the fluid-ejection elements 108 to which the circuitry 210 is immediately adjacent. For instance, each circuitry 210 may control and monitor the fluid-ejection element 108-2 of the group 107 to the left of the circuitry 210 and the fluid-ejection element 108-1 of the group 107 to the right of the circuitry 210. As depicted, the fluid-ejection elements 108-1 and 108-2 of each group 107 may abut one another, such that there is no fluid-ejection element circuitry 210 between the elements 108 of each group 107, where usage of the terminology circuitry does not include any conductive (e.g., metal) traces that directly connect to the elements 108.

[0033] The depicted non-uniform configuration of the elements 108 within the groups 107 permits the area between nonadjacent consecutive groups 107 for the circuitry 210 to be larger than the area between nonadjacent consecutive elements 108 in a uniform configuration in which the elements 108 are not organized within the groups 107. In a uniform configuration, the spacing between each pair of elements 108 is equal. By comparison, in the depicted non-uniform configuration, the spacing between the pair of elements 108 of each group 107 is less than the spacing between each pair of elements 108 belonging to nonadjacent consecutive groups 107. [0034] FIG. 3 shows a top view of another example implementation of the fluid-ejection printhead 100. The fluid-ejection elements 108 are organized in fluid-ejection element groups 107-1 of the fluid-ejection layer 112E, which correspond to the groups 107 of FIG. 2. As in FIG. 2, the groups 107-1 are organized in a chevron configuration to which the channel axis in the example of FIG. 3 corresponds. However, the groups 107-1 may instead be organized in a different configuration, such as a linear configuration as in FIGs. 1A-1 E. The fluid-ejection elements 108 are also organized in FIG. 3 in fluid-ejection element groups 107-2 of the fluid-ejection layer 112E, along a direction 301 across the supply and return channels 106S and 106R of FIGs.

1A-1 E. [0035] Each fluid-ejection element group 107-2 includes two fluidejection elements 108 with respective nozzles 110. The fluid-ejection elements 108 of two groups 107-2 are particularly identified in FIG. 3. Specifically, the fluid-ejection elements 108-1 and 108-3 with respective nozzles 110-1 and 110-3 form one (left) group 107-2, and the fluid-ejection elements 108-2 and 108-4 with respective nozzles 110-2 and 110-4 form another (right) group 107-2. The elements 108-1 and 108-2 still form one (top) group 107-1 , with the elements 108-3 and 108-4 forming another (bottom) group 107-1.

[0036] The fluid-ejection elements 108 of each group 107-2 may be of the same or different type. In the depicted example, the elements 108-1 and 108-3 of one (left) group 107-2 eject fluid at the same drop weight, which is less than the drop weight at which the elements 108-2 and 108-4 of another (right) nonadjacent consecutive group 107-2 eject the fluid. Therefore, the nozzles 110-1 and 110-3 are shown as smaller in size than the nozzles 110-2 and 110-4.

[0037] The inter-group 107-2 spacing 302 may be defined as the distance between centers of nonadjacent consecutive fluid-ejection groups 107-2. The intra-group 107-2 spacing 304 may be defined as the distance between centers of the nozzles 110 of the fluid-ejection elements 108 of each group 107-2, and is less than the spacing 302. The spacing 306 between top elements 108-1 of nonadjacent consecutive groups 107-2 along the direction 301 may be defined as the distance between the centers of their respective nozzles 110, and may be equal to the spacing 302. The spacing 308 between bottom elements 108 of nonadjacent consecutive groups 107-2 along the direction 301 may be defined as the distance between the centers of their respective nozzles 110, and may likewise be equal to the spacing 302.

[0038] The fluid-ejection printhead 100 includes fluid-ejection element circuitry 310 located between nonadjacent consecutive groups 107-2 along the direction 301 . Each fluid-ejection element circuitry 310 can be control and monitoring circuitry for controlling and monitoring the fluid-ejection elements 108 to which the circuitry 310 is immediately adjacent. For instance, each circuitry 310 may control and monitor the fluid-ejection elements 108-3 and 108-4 of the groups 107-2 above the circuitry 310 and the fluid-ejection element 108-1 and 108-2 of the groups 107-2 below the circuitry 310. As depicted, the fluid-ejection elements 108 of each group 107-2 may abut one another, such that there is no circuitry 310 between the elements 108 of each group 107-2. As noted above, usage of the terminology circuitry does not include any conductive (e.g., metal) traces that directly connect to the elements 108. The printhead 100 may also include the circuitry 210 of FIG. 2. [0039] The depicted non-uniform configuration of the elements 108 in which the elements 108 are organized within the groups 107-2 permits the area between nonadjacent consecutive groups 107-2 for the circuitry 310 to be larger than the area between elements 108 in a uniform configuration in which the elements 108 are not organized within the groups 107-2. In a uniform configuration, the spacing between each pair of nonadjacent consecutive elements 108 is equal along the direction 301. By comparison, in the depicted non-uniform configuration, the spacing between the pair of elements 108 of each group 107-2 is less than the spacing between each pair of elements 108 belonging to different nonadjacent consecutive groups 107-2. [0040] In the non-uniform sparse nozzle configurations of FIGs. 2 and 3, the fluid-ejection elements 108 of each group 107/107-1 and 107-2 are aligned with one another. However, as noted, the fluid-ejection elements 108 of each group 107/107-1 and 107-2 may instead be staggered relative to one another. FIG. 4 shows such an example fluid-ejection element group 107 that can instead be used in FIG. 2, and FIG. 5 show such example fluid-ejection element groups 107-1 and 107-2 that can instead be used in FIG. 3. In FIG. 4 the fluid-ejection elements 108-1 and 108-2 of the group 107 are staggered relative to one another. Likewise, in FIG. 5 the elements 108-1/108-3 and 108-2/108-4 of the top and bottom groups 107-1 are staggered relative to one another, as are the elements 108-1/108-2 and 108-3/108-4 of the left and right groups 107-2.

[0041] FIG. 6 shows a block diagram of an example fluid-ejection device 600. The device 600 may, for instance, be an inkjet-printing device, such as a standalone printer or an all-in-one (AIO) device. The device 600 includes fluid-ejection control hardware 602 that controls and/or monitors fluid ejection and by the device 600. The hardware 602 may include controllers implemented as integrated circuits (ICs) like application-specific ICs (ASICs), for instance. The fluid-ejection device 600 includes a fluid-ejection cartridge 150 electrically connected to the hardware 602 and having a cartridge body 160 with slots 102, as well as a fluid-ejection printhead 100 attached to the body 160.

[0042] The fluid-ejection printhead 100 includes a channel layer 112C, an interposer layer 1121, and a fluid-ejection layer 112E. The channel layer

112C includes a supply channel 106S and a return channel 106R. The interposer layer 1121 is below the channel layer 112C and defines an inlet port 104S and an outlet port 104R that fluidically connect the fluid slots 102 to the supply channel 106S and the return channel 106R, respectively. The fluidejection layer 112E is above the channel layer 112C and includes fluid- ejection element groups 107 that each include fluid-ejection elements 1082 fluidically connected to the supply and return channels 106S and 106R. The inter-group 107 spacing is greater than the intra-group 107 spacing.

[0043] Non-uninform sparse nozzle printhead architectures (i.e., non- uniform sparse fluid-ejection element architectures) have been described herein. Printhead architectures having non-uniform sparse configurations increase the contiguous space available between nonadjacent consecutive fluid-ejection element groups for placing fluid-ejection element control and monitoring circuitry. Therefore, more complex or sophisticated circuitry can be included within printheads.

Claims

We claim:

1 . A fluid-ejection printhead comprising: a channel layer having supply and return channels; an interposer layer below the channel layer and defining inlet and outlet ports respectively flu idical ly connected to the supply and return channels; and a fluid-ejection layer above the channel layer and comprising a plurality of fluid-ejection element groups that each include first and second fluidejection elements fluidically connected to the supply and return channels, wherein inter-group spacing along an axis non-perpendicular to a channel axis of the supply and return channels is greater than intra-group spacing along the axis.

2. The fluid-ejection printhead of claim 1 , wherein the inter-group spacing is greater than the intra-group spacing in that a spacing between corresponding fluid-ejection elements of nonadjacent consecutive groups is greater than a spacing between the first and second fluid-ejection elements of each group.

3. The fluid-ejection printhead of claim 1 , wherein a spacing between the first fluid-ejection elements of nonadjacent consecutive groups is uniform.

4. The fluid-ejection printhead of claim 3, wherein a spacing between the second fluid-ejection elements of the nonadjacent consecutive groups is uniform.

5. The fluid-ejection printhead of claim 4, wherein the spacing between the second fluid-ejection elements of the nonadjacent consecutive groups is equal to the spacing between the first fluid-ejection elements of the nonadjacent consecutive groups.

6. The fluid-ejection printhead of claim 5, wherein the spacing between the second fluid-ejection elements of the nonadjacent consecutive groups and the spacing between the first fluid-ejection elements of the nonadjacent consecutive groups is equal to or greater than twice a spacing between the first and second fluid-ejection elements of each group.

7. The fluid-ejection printhead of claim 1 , wherein the first fluid-ejection elements are of a first fluid-ejection element type and the second fluid-ejection elements are of a second fluid-ejection element type different than the first fluid-ejection element type.

8. The fluid-ejection printhead of claim 7, wherein the first fluid-ejection elements eject fluid at a first drop weight and the second fluid-ejection elements eject the fluid at a second drop weight different than the first drop weight.

9. The fluid-ejection printhead of claim 1 , wherein the fluid-ejection layer defines a fluid recirculation path spanning the supply and return channels.

10. The fluid-ejection printhead of claim 1 , further comprising fluid-ejection element circuitry located between nonadjacent consecutive groups.

11 . The fluid-ejection printhead of claim 10, wherein no fluid-ejection element circuitry is located between the first and second fluid-ejection elements of each group.

12. The fluid-ejection printhead of claim 1 , wherein the fluid-ejection element groups are first fluid-ejection element groups, wherein the fluid-ejection layer further comprises a plurality of second fluid-ejection element groups that each include third and fourth fluid-ejection elements along a direction across the supply and return channels, and wherein inter-second group spacing along the direction is greater than a spacing between the third and fourth fluid-ejection elements of each second group.

13. The fluid-ejection printhead of claim 12, further comprising fluidejection element circuitry located between nonadjacent consecutive groups.

14. A fluid-ejection cartridge comprising: a cartridge body defining fluid slots; and a fluid-ejection printhead attached to the cartridge body and comprising: a channel layer having supply and return channels; an interposer layer below the channel layer and defining inlet and outlet ports that fluidical ly connect the fluid slots to the supply and return channels, respectively; and a fluid-ejection layer above the channel layer and comprising a plurality of fluid-ejection element groups that each include fluid-ejection

19 elements fluidically connected to the supply and return channels, wherein inter-group spacing is greater than intra-group spacing.

15. A fluid-ejection device comprising: fluid-ejection control hardware; and a fluid-ejection cartridge electrically connected to the fluid-ejection control hardware and comprising a cartridge body and a fluid-ejection printhead attached to the cartridge body, wherein the fluid-ejection printhead comprises: a channel layer having supply and return channels; an interposer layer below the channel layer and defining inlet and outlet ports that fluidically connect fluid slots of the cartridge body to the supply and return channels, respectively; and a fluid-ejection layer above the channel layer and comprising a plurality of fluid-ejection element groups that each include fluid-ejection elements fluidically connected to the supply and return channels, and wherein inter-group spacing is greater than intra-group spacing.

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