WO2022019917A1

WO2022019917A1 - Fluid ejection assembly

Info

Publication number: WO2022019917A1
Application number: PCT/US2020/043395
Authority: WO
Inventors: Mark Alan DEVRIES; Curt Gene Gonzales
Original assignee: Hewlett-Packard Development Company, L.P.
Priority date: 2020-07-24
Filing date: 2020-07-24
Publication date: 2022-01-27

Abstract

A fluid ejection assembly includes a fluid ejection die, and a fluid container to support the fluid ejection die, the fluid container including a first chamber free of fluid absorbent material, a second chamber including fluid absorbent material, and an intermediate chamber to transfer fluid from a bottom portion of the first chamber to a top portion of the second chamber, with the fluid ejection die to receive fluid from the second chamber.

Description

FLUID EJECTION ASSEMBLY

Background

A fluid ejection die, such as a printhead die in an inkjet printing system, may use thermal resistors or piezoelectric material membranes as actuators within fluidic chambers to eject fluid drops (e.g., ink) from nozzles, such that properly sequenced ejection of ink drops from the nozzles causes characters or other images to be printed on a print medium as the printhead die and the print medium move relative to each other.

Brief Description of the Drawings

FIG. 1 is a schematic view illustrating an example of a fluid ejection assembly.

FIG. 2 is a block diagram illustrating an example of an inkjet printing system including an example of a fluid ejection assembly.

FIG. 3 is a schematic view illustrating an example of a fluid ejection assembly.

FIG. 4 is a schematic view illustrating an example of a fluid ejection assembly.

FIG. 5 is a schematic view illustrating an example of a fluid ejection assembly.

FIG. 6 is a schematic view illustrating an example of a fluid ejection assembly. FIG. 7 is a cross-sectional view illustrating an example of a fluid ejection assembly.

FIG. 8 is an exploded perspective view illustrating an example of the fluid ejection assembly of FIG. 7.

FIG. 9 is a flow diagram illustrating an example of a method of supplying fluid for a fluid ejection die.

Detailed Description

In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration specific examples in which the disclosure may be practiced. It is to be understood that other examples may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure.

As illustrated in the example of FIG. 1 , the present disclosure provides a fluid ejection assembly 10. In one implementation, fluid ejection assembly 10 includes a fluid ejection die 12, and a fluid container 14 to support fluid ejection die 12, with fluid container 14 including a first chamber 15 free of fluid absorbent material, a second chamber 17 including fluid absorbent material 18, and an intermediate chamber 16 to transfer fluid 13 from a bottom portion of first chamber 15 to a top portion of second chamber 17, as represented by arrow 19, such that fluid ejection die 12 is to receive fluid 13 from second chamber 17.

FIG. 2 illustrates an example of an inkjet printing system 100 including a printhead assembly 102, as an example of a fluid ejection device, a fluid supply assembly 104, a mounting assembly 106, a media transport assembly 108, an electronic controller 110, and a power supply 112 that provides power to electrical components of inkjet printing system 100. Printhead assembly 102 includes a printhead die 114, as an example of a fluid ejection die, that ejects drops of fluid through a plurality of orifices or nozzles 116 toward a print media 118 so as to print on print media 118. Print media 118 can be any type of suitable sheet or roll material, such as paper, card stock, transparencies, Mylar, and the like, and may include rigid or semi-rigid material, such as cardboard or other panels. Nozzles 116 are typically arranged in columns or arrays such that properly sequenced ejection of fluid from nozzles 116 causes characters, symbols, and/or other graphics or images to be printed on print media 118 as printhead assembly 102 and print media 118 are moved relative to each other.

Fluid supply assembly 104 supplies fluid (e.g., ink or other liquid) to printhead assembly 102 such that fluid flows from fluid supply assembly 104 to printhead assembly 102. In one example, printhead assembly 102 and fluid supply assembly 104 are housed together in an inkjet cartridge or pen 120, as an example of a fluid ejection assembly. In another example, fluid supply assembly 104 is separate from printhead assembly 102 and supplies fluid to printhead assembly 102 through an interface connection, such as a supply tube.

Mounting assembly 106 positions printhead assembly 102 relative to media transport assembly 108, and media transport assembly 108 positions print media 118 relative to printhead assembly 102. Thus, a print zone 122 is defined adjacent to nozzles 116 in an area between printhead assembly 102 and print media 118. In one example, printhead assembly 102 is a scanning type printhead assembly. As such, mounting assembly 106 includes a carriage for moving printhead assembly 102 relative to media transport assembly 108 to scan print media 118. In another example, printhead assembly 102 is a non scanning type printhead assembly. As such, mounting assembly 106 fixes printhead assembly 102 at a prescribed position relative to media transport assembly 108. Thus, media transport assembly 108 positions print media 118 relative to printhead assembly 102.

Electronic controller 110 typically includes a processor, firmware, software, memory components including volatile and non-volatile memory components, and other printer electronics for communicating with and controlling printhead assembly 102, mounting assembly 106, and media transport assembly 108. Electronic controller 110 receives data 124 from a host system, such as a computer, and temporarily stores data 124 in a memory. Typically, data 124 is sent to inkjet printing system 100 along an electronic, infrared, optical, or other information transfer path. Data 124 represents, for example, a document and/or file to be printed. As such, data 124 forms a print job for inkjet printing system 100 and includes print job commands and/or command parameters.

In one example, electronic controller 110 controls printhead assembly 102 for ejection of fluid drops from nozzles 116. Thus, electronic controller 110 defines a pattern of ejected fluid drops which form characters, symbols, and/or other graphics or images on print media 118. The pattern of ejected fluid drops is determined by the print job commands and/or command parameters.

Printhead assembly 102 includes one (i.e., a single) printhead die 114 or more than one (i.e., multiple) printhead die 114. In one example, printhead assembly 102 is a wide-array or multi-head printhead assembly. In one implementation of a wide-array assembly, printhead assembly 102 includes a carrier that carries a plurality of printhead dies 114, provides electrical communication between printhead dies 114 and electronic controller 110, and provides fluidic communication between printhead dies 114 and fluid supply assembly 104.

In one example, inkjet printing system 100 is a drop-on-demand thermal inkjet printing system wherein printhead assembly 102 includes a thermal inkjet (TIJ) printhead that implements a thermal resistor as a drop ejecting element to vaporize fluid in a fluid chamber and create bubbles that force fluid drops out of nozzles 116. In another example, inkjet printing system 100 is a drop-on- demand piezoelectric inkjet printing system wherein printhead assembly 102 includes a piezoelectric inkjet (PIJ) printhead that implements a piezoelectric actuator as a drop ejecting element to generate pressure pulses that force fluid drops out of nozzles 116.

FIG. 3 is a schematic view illustrating an example of a fluid ejection assembly 200. In the illustrated example, fluid ejection assembly 200 includes a fluid ejection die 220, as an example of printhead die 114 of printhead assembly 102 (FIG. 2), and a fluid container 240, as an example of fluid supply assembly 104 (FIG. 2). As disclosed herein, fluid ejection die 220 is supported by and is to receive fluid 230 from fluid container 240.

In one implementation, fluid ejection die 220, as an example of printhead die 114 (FIG. 2), includes a drop-on-demand thermal inkjet (TIJ) printhead, as described above. In another implementation, fluid ejection die 220, as an example of printhead die 114 (FIG. 2), includes a drop-on-demand piezoelectric inkjet (PIJ) printhead, as described above. In either example, fluid ejection die 220 includes orifices or nozzles, such as orifices or nozzles 116 (FIG. 2), through which drops of fluid (e.g., ink or other liquid) are ejected, as described above. In one example, fluid ejection die 220 includes a thin-film structure formed on a substrate with the substrate formed, for example, of silicon, glass, or a stable polymer, and the thin-film structure including conductive, passivation or insulation layers.

In one example, fluid container 240 supports fluid ejection die 220 such that fluid container 240 supplies fluid 230 (e.g., ink or other liquid) to fluid ejection die 220. In one implementation, fluid container 240 includes a first chamber 250, a second chamber 270, and an intermediate chamber 260 between first chamber 250 and second chamber 270. More specifically, intermediate chamber 260 is in fluid communication with first chamber 250 and second chamber 270. As such, intermediate chamber 260 provides for transfer of fluid 230 between first chamber 250 and second chamber 270, including transfer of fluid 230 from first chamber 250 to second chamber 270, as represented by arrow 242.

In the illustrated example, intermediate chamber 260 has a first end 261 open to first chamber 250 and a second end 262, opposite first end 261 , open to second chamber 270. In one implementation, first end 261 is open to a bottom portion 252 of first chamber 250 and second end 262 is open to a top portion 271 of second chamber 270. As such, intermediate chamber 260 provides for transfer of fluid 230 between bottom portion 252 of first chamber 250 and top portion 271 of second chamber 270, including transfer of fluid 230 from bottom portion 252 of first chamber 250 to top portion 271 of second chamber 270. In examples, fluid ejection die 220 is in fluid communication with second chamber 270 such that fluid ejection die 220 receives fluid 230 from second chamber 270. In one implementation, fluid ejection die 220 is in fluid communication with and receives fluid 230 from a bottom portion 272 of second chamber 270.

As schematically illustrated in the example of FIG. 3, first chamber 250 is free of fluid absorbent material, and second chamber 270 includes a fluid absorbent material 280. As such, first chamber 250 represents a free-fluid reservoir, and second chamber 270 represents a fluid absorbent reservoir. In one implementation, fluid absorbent material 280 is a foam material positioned within second chamber 270. As such, fluid absorbent material 280 helps to control fluid flow to and regulate fluid pressure at fluid ejection die 220. For example, fluid absorbent material 280 provides back pressure (i.e., negative pressure) to fluid ejection die 220 during ejection of fluid therefrom.

As disclosed herein, with fluid 230 in fluid container 240, bottom portion 252 of first chamber 250 is below a surface of fluid 230 in first chamber 250, and top portion 271 of second chamber 270 includes an air chamber 273 above fluid absorbent material 280 in second chamber 270. As such, with fluid 230 in fluid container 240, first end 261 of intermediate chamber 260 communicates with fluid 230 in first chamber 250 and second end 262 of intermediate chamber 260 communicates with air in second chamber 270. More specifically, second end 262 of intermediate chamber 260 communicates with air chamber 273 of second chamber 270 above fluid absorbent material 280.

In examples, first end 261 of intermediate chamber 260 is submersed in fluid 230 in first chamber 250 and second end 262 of intermediate chamber 260 is exposed to air in second chamber 270. As such, intermediate chamber 260 comprises or represents a snorkel communicated with first chamber 250 and second chamber 270.

In the illustrated example, intermediate chamber 260 has a longitudinal axis 263. In addition, a depth of fluid 230 in first chamber 250, as measured from a surface of fluid 230 in first chamber 250, is represented by arrow d. As such, in one implementation, longitudinal axis 263 of intermediate chamber 260 is oriented substantially parallel with depth d of fluid 230 in first chamber 250. Accordingly, intermediate chamber 260 (along longitudinal axis 263) leads fluid 230 from first chamber 250 to second chamber 270 in a direction opposite of and oriented substantially parallel with depth d of fluid 230 in first chamber 250. Thus, in examples, intermediate chamber 260 (along longitudinal axis 263) leads fluid 230 from first chamber 250 to second chamber 270 in a direction opposite of a force of gravity.

In the illustrated example, fluid ejection die 220 ejects drops of fluid in a direction indicated by arrow D. As such, longitudinal axis 263 of intermediate chamber 260 is oriented substantially parallel with direction D of ejection of drops of fluid from fluid ejection die 220. Accordingly, intermediate chamber 260 directs fluid in a direction opposite of and oriented substantially parallel with direction D of ejection of drops of fluid from fluid ejection die 220.

In one example, fluid ejection assembly 200 includes a filter 282 in a fluid path between first chamber 250 and intermediate chamber 260. More specifically, in one implementation, filter 282 is provided at and/or provided in a fluid path communicated with first end 261 of intermediate chamber 260. As such, filter 282 filters fluid supplied to intermediate chamber 260 (and, therefore, second chamber 270) from first chamber 250.

In one example, fluid ejection assembly 200 includes a filter 284 in a fluid path between second chamber 270 and fluid ejection die 220. More specifically, in one implementation, filter 284 is provided in bottom portion 272 of second chamber 270 below fluid absorbent material 280. As such, filter 284 filters fluid supplied to fluid ejection die 220 from second chamber 270.

In one example, fluid container 240 includes a vent 286 communicated with first chamber 250. In one implementation, vent 286 communicates with first chamber 250 above a surface of fluid in first chamber 250. As such, vent 286 allows air to pass into and out of first chamber 250. In one implementation, vent 286 includes a labyrinth or serpentine structure or channel to increase the length of and thereby slow the rate of evaporation through vent 286. Although one vent 286 is illustrated, first chamber 250 may include one vent 286 or more than one vent 286. FIG. 4 is a schematic view illustrating an example of a fluid ejection assembly 300. Similar to fluid ejection assembly 200, fluid ejection assembly 300 includes a fluid ejection die 320, as an example of printhead die 114 of printhead assembly 102 (FIG. 2), and a fluid container 340, as an example of fluid supply assembly 104 (FIG. 2). Similar to fluid ejection die 220 and fluid container 240, fluid ejection die 320 is supported by and is to receive fluid 330 from fluid container 340.

In one implementation, and similar to fluid container 240, fluid container 340 includes a first chamber 350, a second chamber 370, and an intermediate chamber 360 between first chamber 350 and second chamber 370, with intermediate chamber 360 having a first end 361 open to first chamber 350 and a second end 362, opposite first end 361 , open to second chamber 370 such that intermediate chamber 360 provides for transfer of fluid 330 between a bottom portion 352 of first chamber 350 and a top portion 371 of second chamber 370. In addition, and similar to fluid container 240, first chamber 350 of fluid container 340 is free of fluid absorbent material, and second chamber 370 of fluid container 340 includes a fluid absorbent material 380. Furthermore, and similar to fluid container 240, fluid container 340 includes a filter 382, a filter 384, and a vent 386.

In the illustrated example, fluid ejection assembly 300 includes a compliant member 390 communicated with second chamber 370. More specifically, in one implementation, compliant member 390 communicates with top portion 371 of second chamber 370. As such, compliant member 390 expands or inflates with air (e.g., from intermediate chamber 360 and/or air chamber 373 of second chamber 370) as fluid 330 is transferred from first chamber 350 to second chamber 370 via intermediate chamber 360. Thus, less air is introduced into fluid absorbent material 380 as fluid 330 is introduced into second chamber 370.

Furthermore, with compliant member 390, the volume of fluid in intermediate chamber 360 (to account for expansion of air in top portion 371 of second chamber 370 during temperature and/or pressure/altitude variation) and, therefore, the size of intermediate chamber 360, may be reduced. For example, as air in top portion 371 of second chamber 370 and absorbent material 380 expands (due to temperature and/or pressure/altitude variation), the air may push fluid in intermediate chamber 360 back into first chamber 350 until the air hits filter 382. In examples, the air then pressurizes intermediate chamber 360 and second chamber 370 (i.e., air does not readily pass through filter 382), which can cause fluid to leak out of nozzles of fluid ejection die 220 (i.e., drool). However, with compliant member 390 (which is normally deflated due to slight negative pressure in top portion 371 of second chamber 370), compliant member 390 may expand or inflate with air and, therefore, eliminate or delay the onset of drool. In one implementation, compliant member 390 includes a compliant bag.

FIG. 5 is a schematic view illustrating an example of a fluid ejection assembly 400. Similar to fluid ejection assembly 200, fluid ejection assembly 400 includes a fluid ejection die 420, as an example of printhead die 114 of printhead assembly 102 (FIG. 2), and a fluid container 440, as an example of fluid supply assembly 104 (FIG. 2). Similar to fluid ejection die 220 and fluid container 240, fluid ejection die 420 is supported by and is to receive fluid 430 from fluid container 440.

In one implementation, and similar to fluid container 240, fluid container 440 includes a first chamber 450, a second chamber 470, and an intermediate chamber 460 between first chamber 450 and second chamber 470. In addition, and similar to fluid container 240, first chamber 450 of fluid container 440 is free of fluid absorbent material, and second chamber 470 of fluid container 440 includes a fluid absorbent material 480.

In the illustrated example, fluid ejection assembly 400 includes a fluid refill system 410. In one implementation, fluid refill system 410 includes a fluid reservoir 412, a pump 414, and a fluid sensor 416, with a supply line 413 extending between and fluidically communicated with fluid reservoir 412 and pump 414, and a supply line 415 extending between and fluidically communicated with pump 414 and fluid container 440, including, more specifically, first chamber 450 of fluid container 440. In examples, fluid reservoir 412 is external to fluid container 440 and includes a quantity of fluid 430 (e.g., ink or other liquid), such that pump 414 transfers fluid 430 from fluid reservoir 412 to fluid container 440, including, more specifically, to first chamber 450 of fluid container 440, via supply lines 413, 415. As such, fluid container 440 is re filled (or filled) with fluid 430 from fluid reservoir 412 as an external fluid reservoir.

In one example, pump 414 is operated (to transfer fluid from fluid reservoir 412 to fluid container 440) based on a level of fluid 430 within first chamber 450 of fluid container 440, as sensed, detected or measured by fluid sensor 416. In one implementation, fluid sensor 416 includes fluid detection members 416a and 416b to detect a level of fluid 430 in first chamber 450 (e.g., a presence or absence of fluid above or below a level).

In an example, fluid detection members 416a and 416b include electrical conductors such as non-corrosive metallic pins, posts, electrodes, or the like, such that one end of the electrical conductors is disposed within first chamber 450, and the other end of the electrical conductors is connected to an electrical sensing circuit. Thus, in one implementation, fluid detection members 416a and 416b detect the presence of fluid in first chamber 450 (e.g., fluid above a level) when fluid is in contact with each of fluid detection members 416a and 416b, and detect the absence of fluid in first chamber 450 (e.g., fluid below a level) when fluid is not in contact with each of fluid detection members 416a and 416b.

FIG. 6 is a schematic view illustrating an example of a fluid ejection assembly 500. Similar to fluid ejection assembly 200, fluid ejection assembly 500 includes a fluid ejection die 520, as an example of printhead die 114 of printhead assembly 102 (FIG. 2), and a fluid container 540, as an example of fluid supply assembly 104 (FIG. 2). Similar to fluid ejection die 220 and fluid container 240, fluid ejection die 520 is supported by and is to receive fluid 530 from fluid container 540.

In one implementation, and similar to fluid container 240, fluid container 540 includes a first chamber 550, a second chamber 570, and an intermediate chamber 560 between first chamber 550 and second chamber 570. In addition, and similar to fluid container 240, first chamber 550 of fluid container 540 is free of fluid absorbent material, and second chamber 570 of fluid container 540 includes a fluid absorbent material 580.

In the illustrated example, fluid ejection assembly 500 includes a fluid refill system 510. In one implementation, fluid refill system 510 includes a fluid reservoir 512, an interconnect 511 , and a pump 518, with a supply line 513 extending between and fluidically communicated with fluid reservoir 512 and interconnect 511 , a return line 517 extending between and communicated with pump 518 and fluid container 540, including, more specifically, first chamber 550 of fluid container 540, and a return line 519 extending between and communicated with pump 518 and fluid reservoir 512. In examples, fluid reservoir 512 is external to fluid container 540 and includes a quantity of fluid 530 (e.g., ink or other liquid), such that fluid 530 is transferred from fluid reservoir 512 to fluid container 540 through interconnect 511 , including, more specifically, to first chamber 550 of fluid container 540, via supply line 513 as air is removed from first chamber 550 by pump 518 via return lines 517 and 519. More specifically, pump 518 pulls air off of a top of first chamber 550 and, when first chamber 550 is full of fluid, pumps fluid. As such, fluid container 540 is re filled (or filled) with fluid 530 from fluid reservoir 512.

FIG. 7 is a cross-sectional view illustrating an example of a fluid ejection assembly 600, and FIG. 8 is an exploded perspective view illustrating an example of fluid ejection assembly 600. Similar to fluid ejection assembly 200, fluid ejection assembly 600 includes a fluid ejection die 620, as an example of printhead die 114 of printhead assembly 102 (FIG. 2), and a fluid container 640, as an example of fluid supply assembly 104 (FIG. 2). Similar to fluid ejection die 220 and fluid container 240, fluid ejection die 620 is supported by and is to receive fluid 630 from fluid container 640.

In one implementation, and similar to fluid container 240, fluid container 640 includes a first chamber 650, a second chamber 670, and an intermediate chamber 660 between first chamber 650 and second chamber 670. In one example, fluid container 640 includes a manifold 644 between intermediate chamber 660 and second chamber 670. As such, intermediate chamber 660, via manifold 644, provides for transfer of fluid 630 between first chamber 650 and second chamber 670, including transfer of fluid 630 from first chamber 650 to second chamber 670, as represented by arrow 642. More specifically, intermediate chamber 660, via manifold 644, provides for transfer of fluid 630 between a bottom portion 652 of first chamber 650 and a top portion 671 of second chamber 670, including transfer of fluid 630 from bottom portion 652 of first chamber 650 to top portion 671 of second chamber 670. In one implementation, fluid ejection die 620 is in fluid communication with and receives fluid 630 from a bottom portion 672 of second chamber 670.

In the illustrated example, fluid container 640 includes a body 646 and a lid 648, with body 646 having first chamber 650 and second chamber 670 defined or formed therein, and lid 648 having intermediate chamber 660 defined or formed therein. In one implementation, manifold 644 is supported by lid 648 with a gasket 645 therebetween. As such, gasket 645 facilitates a joint (e.g., welded joint or glued joint) between manifold 644 and lid 648 and/or helps to provide a fluid-tight seal between manifold 644 and lid 648.

In one implementation, and similar to fluid container 240, first chamber 650 of fluid container 640 is free of fluid absorbent material, and second chamber 670 of fluid container 640 includes a fluid absorbent material 680. As such, first chamber 650 represents a free-fluid reservoir, and second chamber 670 represents a fluid absorbent reservoir. In one implementation, fluid absorbent material 680 is a foam material positioned within second chamber 670. As such, fluid absorbent material 680 helps to control fluid flow to and regulate fluid pressure at fluid ejection die 620. For example, fluid absorbent material 680 provides back pressure (i.e., negative pressure) to fluid ejection die 620 during ejection of fluid therefrom.

In examples, a first end 661 of intermediate chamber 660 is submersed in fluid 630 in first chamber 650 and a second end 662 of intermediate chamber 660, via manifold 644, is exposed to air in second chamber 670. More specifically, second end 662 of intermediate chamber 660 communicates with an air chamber 673 of second chamber 670 above fluid absorbent material 680. As such, intermediate chamber 660, with manifold 644, comprises or represents a snorkel communicated with first chamber 650 and second chamber 670. In the illustrated example, intermediate chamber 660 has a longitudinal axis 663. In addition, a depth of fluid 630 in first chamber 650, as measured from a surface of fluid 630 in first chamber 650, is represented by arrow d. As such, in one implementation, longitudinal axis 663 of intermediate chamber 660 is oriented substantially parallel with depth d of fluid 630 in first chamber 650. Accordingly, intermediate chamber 660 (along longitudinal axis 663) leads fluid 630 from first chamber 650 to second chamber 670 in a direction opposite of and oriented substantially parallel with depth d of fluid 630 in first chamber 650. In addition, in the illustrated example, manifold 644 leads fluid 630 in a direction oriented substantially perpendicular to depth d of fluid 630 in first chamber 650.

In one example, fluid ejection assembly 600 includes a filter 682 in a fluid path between first chamber 650 and intermediate chamber 660. More specifically, in one implementation, filter 682 is provided at first end 661 of intermediate chamber 660. As such, filter 682 filters fluid supplied to intermediate chamber 660 (and, therefore, second chamber 670) from first chamber 650.

In one example, fluid container 640 includes a vent 686 communicated with first chamber 650. In one implementation, vent 686 communicates with first chamber 650 above a surface of fluid in first chamber 650. As such, vent 686 allows air to pass into and out of first chamber 650. In one implementation, vent 686 includes a membrane 687 which allows air to pass therethrough but prevents fluid from passing therethrough, and a labyrinth structure 688 (FIG. 8) to increase the length of and thereby slow the rate of evaporation through vent 686. Although two vents 686 (FIG. 8) are illustrated, first chamber 650 may include one vent 686, two vents 686, or more than two vents 686.

FIG. 9 is a flow diagram illustrating an example of a method 800 of supplying fluid for a fluid ejection die, such as fluid ejection die 220, 320, 620 of fluid ejection assembly 200, 300, 600 as illustrated, for example, in FIGS. 3, 4,

7, respectively.

At 802, method 800 includes communicating fluid from a free-fluid reservoir to a fluid absorbent reservoir through a snorkel having a first end submersed in fluid within the free-fluid reservoir and a second end opposite the first end exposed to air within the fluid absorbent reservoir, such as communicating fluid 230, 330, 630 from first chamber 250, 350, 650 to second chamber 270, 370, 670 through intermediate chamber 260, 360, 660, with first end 261 , 361 , 661 submersed in fluid 230, 330, 630 within first chamber 250, 350, 650 and second end 262, 362, 662 exposed to air within second chamber 270, 370, 670, as illustrated, for example, in FIGS. 3, 4, 7, respectively.

At 804, method 800 includes communicating fluid of the fluid absorbent reservoir with the fluid ejection die, such as communicating fluid 230, 330, 630 of second chamber 270, 370, 670 with fluid ejection die 220, 320, 620, as illustrated, for example, in FIGS. 3, 4, 7, respectively.

In one example, communicating fluid from the free-fluid reservoir to the fluid absorbent reservoir, at 802, includes transferring fluid 230, 330, 630 from a bottom portion 252, 352, 652 of first chamber 250, 350, 650 to a top portion 271 , 371 , 671 of second chamber 270, 370, 670 through intermediate chamber 260, 360, 660, as illustrated, for example, in FIGS. 3, 4, 7, respectively.

A fluid ejection assembly, as disclosed herein, combines a free-fluid reservoir with a fluid absorbent reservoir. As such, the free-fluid reservoir provides a refillable chamber, which can be refilled any time, while the fluid absorbent reservoir provides a pressure regulating chamber which can control fluid flow to and regulate fluid pressure at the fluid ejection die.

Example fluid ejection assemblies, as described herein, may be implemented in printing devices, such as two-dimensional printers and/or three- dimensional printers (3D). As will be appreciated, some example fluid ejection assemblies may be printheads. In some examples, a fluid ejection assembly may be implemented in a printing device to print content onto media, such as paper, and/or print a layer of build material. Example fluid ejection assemblies include ink-based ejection devices, digital titration devices, 3D printing devices, pharmaceutical dispensation devices, reactive devices (such as lab-on-a-chip devices), fluidic diagnostic circuits, and/or other such devices in which amounts of fluids may be dispensed/ejected.

Although specific examples have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations may be substituted for the specific examples shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific examples discussed herein.

Claims

1. A fluid ejection assembly, comprising: a fluid ejection die; and a fluid container to support the fluid ejection die, the fluid container including a first chamber free of fluid absorbent material, a second chamber including fluid absorbent material, and an intermediate chamber to transfer fluid from a bottom portion of the first chamber to a top portion of the second chamber, the fluid ejection die to receive fluid from the second chamber.

2. The fluid ejection assembly of claim 1 , the bottom portion of the first chamber to be below a surface of fluid in the first chamber, and the top portion of the second chamber including an air chamber above the fluid absorbent material in the second chamber.

3. The fluid ejection assembly of claim 1 , the intermediate chamber having a longitudinal axis to be oriented substantially parallel with a depth of fluid in the first chamber.

4. The fluid ejection assembly of claim 1 , the intermediate chamber to transfer fluid in a direction opposite a direction of ejection of drops of fluid from the fluid ejection die.

5. The fluid ejection assembly of claim 1 , the fluid container including a vent communicated with the first chamber.

6. The fluid ejection assembly of claim 1 , further comprising: a filter in a fluid path between the first chamber and the intermediate chamber.

7. The fluid ejection assembly of claim 1 , further comprising: a compliant member communicated with the top portion of the second chamber.

8. A fluid container, comprising: a free-fluid reservoir; a fluid absorbent reservoir; and a snorkel communicated with the free-fluid reservoir and the fluid absorbent reservoir, the snorkel having a first end to be submersed in fluid in the free-fluid reservoir and a second end opposite the first end to be exposed to air in the fluid absorbent reservoir.

9. The fluid container of claim 8, further comprising: fluid absorbent material in the fluid absorbent reservoir, the second end of the snorkel to communicate with the fluid absorbent reservoir above the fluid absorbent material.

10. The fluid container of claim 8, the snorkel to lead fluid from the free-fluid reservoir to the fluid absorbent reservoir in a direction opposite of a force of gravity.

11. The fluid container of claim 8, further comprising: a vent communicated with the free-fluid reservoir; and a filter communicated with the first end of the snorkel.

12. A method of supplying fluid for a fluid ejection die, comprising: communicating fluid from a free-fluid reservoir to a fluid absorbent reservoir through a snorkel having a first end to be submersed in fluid within the free-fluid reservoir and a second end opposite the first end to be exposed to air within the fluid absorbent reservoir; and communicating fluid of the fluid absorbent reservoir with the fluid ejection die.

13. The method of claim 12, wherein communicating fluid from the free-fluid reservoir to the fluid absorbent reservoir includes transferring fluid from a bottom portion of the free-fluid reservoir to a top portion of the fluid absorbent reservoir through the snorkel.

14. The method of claim 13, wherein the fluid absorbent reservoir includes fluid absorbent material, and wherein transferring fluid through the snorkel includes transferring fluid from the bottom portion of the free-fluid reservoir to the top portion of the fluid absorbent reservoir above the fluid absorbent material.

15. The method of claim 12, further comprising: supplying fluid to the free-fluid reservoir from an external fluid reservoir.