GB2554709A

GB2554709A - Droplet deposition head

Info

Publication number: GB2554709A
Application number: GB1616946.8A
Authority: GB
Inventors: Brunahl Jurgen; Boltryk Peter; Errol Mcmullen Robert; Kanaris Athanasios
Original assignee: Xaar Technology Ltd
Current assignee: Xaar Technology Ltd
Priority date: 2016-10-05
Filing date: 2016-10-05
Publication date: 2018-04-11
Also published as: WO2018065744A1; GB201616946D0

Abstract

A droplet deposition head 1 includes an actuator component 100 made up of a plurality of patterned layers 4, 2, 20, 30, 40. A row of fluid chambers 10 is formed within the plurality of layers. Each fluid chamber is provided with a respective nozzle 18 and a respective actuating element 22, which is actuable to cause the ejection of fluid from the chamber and corresponding nozzle. A row of inlet passageways 12 and outlet passageways 16 are also formed within the layers of the actuator component. Each inlet and outlet passageways are fluidically connected to a respective one of the fluid chambers. The actuator component further includes a number of conductive traces 30 provided on one of the layers of the actuator component. The conductive traces provide at least part of the electrical connection between the actuating elements and drive circuitry. There is also provided an inlet manifold chamber 255 and an outlet manifold chamber 260. The inlet and outlet manifold chambers are fluidically connected to substantially all of the inlet and outlet passageways respectively. Substantially all of the inlet and outlet passageways cross the plane in which the conductive traces extend, passing between the conductive traces.

Description

(54) Title of the Invention: Droplet deposition head Abstract Title: Droplet deposition head (57) A droplet deposition head 1 includes an actuator component 100 made up of a plurality of patterned layers 4, 2, 20, 30, 40. A row of fluid chambers 10 is formed within the plurality of layers. Each fluid chamber is provided with a respective nozzle 18 and a respective actuating element 22, which is actuable to cause the ejection of fluid from the chamber and corresponding nozzle. A row of inlet passageways 12 and outlet passageways 16 are also formed within the layers of the actuator component. Each inlet and outlet passageways are fluidically connected to a respective one of the fluid chambers. The actuator component further includes a number of conductive traces 30 provided on one of the layers of the actuator component. The conductive traces provide at least part of the electrical connection between the actuating elements and drive circuitry. There is also provided an inlet manifold chamber 255 and an outlet manifold chamber 260. The inlet and outlet manifold chambers are fluidically connected to substantially all of the inlet and outlet passageways respectively. Substantially all of the inlet and outlet passageways cross the plane in which the conductive traces extend, passing between the conductive traces.

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DROPLET DEPOSITION HEAD

The present invention relates to droplet deposition heads and may find particularly beneficial application in a printhead, such as an inkjet printhead.

Droplet deposition heads are now in widespread usage, whether in more traditional applications, such as inkjet printing, or in 3D printing, or other materials deposition or rapid prototyping techniques. Accordingly, the fluids may have novel chemical properties to adhere to new substrates and increase the functionality of the deposited material.

Recently, inkjet printheads have been developed that are capable of depositing ink directly onto ceramic tiles, with high reliability and throughput. This allows the patterns on the tiles to be customized to a customer’s exact specifications, as well as reducing the need for a full range of tiles to be kept in stock.

In other applications, inkjet printheads have been developed that are capable of depositing ink directly on to textiles. As with ceramics applications, this may allow the patterns on the textiles to be customized to a customer’s exact specifications, as well as reducing the need for a full range of printed textiles to be kept in stock.

In still other applications, droplet deposition heads may be used to form elements such as colour filters in LCD or OLED elements displays used in flat-screen television manufacturing.

So as to be suitable for new and/or increasingly challenging deposition applications, droplet deposition heads continue to evolve and specialise. However, while a great many developments have been made, there remains room for improvements in the field of droplet deposition heads.

SUMMARY

Aspects of the invention are set out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference is now directed to the drawings, in which:

Figure 1A is a plan view of a cross-section taken along the length of a fluid chamber 10 of a droplet deposition head according to an example embodiment;

Figure 1B is a cross-section taken in plane 1B indicated in Figure 1A through the fluid chamber substrate layer of the droplet deposition head shown therein;

Figure 1C is a plan view of the actuator component of the droplet deposition head of Figures 1A and 1B taken from the side to which the capping layer is attached, with the capping layer removed so as to show clearly an example layout of the traces;

Figure 1D illustrates the head of Figures 1A-1C operating in a recirculation mode;

Figure 1E is a view of a cross-section through the inlet manifold chamber of the head shown in Figures 1A-1D;

Figure 1F is a view of a cross-section through the outlet manifold chamber of the head shown in Figures 1A-1E;

Figure 2 illustrates a further example embodiment of a droplet deposition head, which includes a modified version of the actuator component of the head shown in Figures 1A-1F;

Figure 3 is a partially exploded perspective view of a droplet deposition head according to a further example embodiment, with the manifold component of the head shown in crosssection so as to illustrate its interior features;

Figures 4A-4C are side views of cross-sections, each of which is taken along the length of the fluid chambers of a respective example of an actuator component, each of which may be utilised in droplet deposition heads described herein

Figure 5 illustrates a further example embodiment of a droplet deposition head;

Figure 6 is a plan view of the actuator component of the droplet deposition head of Figure 5 taken from the side to which the capping layer is attached, with the capping layer removed so as to show clearly an example layout of the traces; and

Figure 7 is a plan view of the actuator component of the droplet deposition head of Figure 5 taken from the side to which the capping layer is attached, with the capping layer removed so as to show clearly a further example layout of the traces.

DETAILED DESCRIPTION OF THE DRAWINGS

Figures 1A-1F illustrate a droplet deposition head 1 according to an example embodiment.

Figure 1A is a plan view of a cross-section taken along the length of a fluid chamber 10 of a droplet deposition head 1 according to an example embodiment.

As may be seen from Figure 1A, the example droplet deposition head 1 includes an actuator component 100 and a manifold component 200.

-2As is also apparent from Figure 1A, the actuator component 100 includes a number of patterned layers that are stacked in a layering direction L (which in Figure 1A is the vertical direction). As is also shown in Figure 1A, each of the patterned layers extends in a plane perpendicular to the layering direction L.

In the particular actuator component 100 shown in Figure 1A, the patterned layers include nozzle layer 4, fluid chamber substrate layer 2, membrane layer 20, wiring and passivation layers 30, and capping layer 40 (in that order). However, this particular combination of layers is by no means essential and, as will be explained in further detail below, additional layers may be included and/or certain layers may be omitted.

As may be seen from Figure 1B, which is a cross-section taken in plane 1B indicated in Figure 1A through fluid chamber substrate layer 2, a row of fluid chambers 10 is formed within the layers of the actuator component 100, with this row extending in a row direction R, which is substantially perpendicular to the layering direction. The row direction R is into the page in Figure 1A.

As may also be seen from Figure 1B, in the particular example embodiment shown in Figures 1A-1F, adjacent chambers within the row are separated by chamber walls 11. As shown in the drawing, the chambers 10 may be elongate in a depth direction D , which is perpendicular to the row direction R and to the layering direction L.

Also formed within the layers of the actuator component 100 are respective rows of inlet passageways 12 and outlet passageways 16, with each of these rows extending in the same row direction R as the row of fluid chambers 10. Thus, the rows of inlet passageways 12, outlet passageways 16 and fluid chambers 10 all extend parallel to one another.

Each inlet passageway 12 is fluidically connected so as to supply fluid to a respective one of the row of fluid chambers 10. Conversely, each outlet passageway 16 is fluidically connected so as to receive fluid from a respective one of the row of fluid chambers 10.

In the specific actuator component 100 of Figures 1A-1C, each inlet passageway 12 is fluidically connected to supply droplet fluid to one end of the corresponding one of the fluid chambers 10, whereas each outlet passageway 16 is fluidically connected to receive fluid from the other end of that fluid chamber 10.

In more detail, as is apparent from Figure 1A, the inlet and outlet passageways 12 are fluidically connected to their corresponding ends of the fluid chamber 10 via respective flow restrictor passages 14a, 14b.

-3As shown in Figure 1A, each of the fluid chambers 10 is provided with a respective nozzle 18 and a respective actuating element 22. The actuating elements 22 are electrically connected to drive circuitry by a plurality of traces 32 (which, in the particular example embodiment shown, are part of the wiring and passivation layer 30), for example so as to allow drive waveforms generated by such drive circuitry to be applied to the actuating elements 22. An example of a suitable layout for the traces 32 is illustrated in Figure 1C, which is a plan view of the actuator component 100 from the side to which the capping layer 40 is attached, with the capping layer 40 removed so as to show clearly the layout of the traces 32.

As may be appreciated from a comparison of Figure 1A with Figure 1C, the traces 32 extend in a plane having a normal in the layering direction L. In the particular example embodiment shown in Figures 1A-1F, the traces 32 are provided on the membrane layer 20; however, in other examples the traces 32 could be provided on another appropriate layer of the actuator component 100.

As is also apparent from comparing these drawings, all of the inlet and outlet passageways 12, 16 cross the plane in which the traces 32 extend.

As noted above, the example droplet deposition head 1 includes a manifold component 200 in addition to actuator component 100. In the particular example embodiment shown in Figure 1A, the manifold component 200 is attached to the opposite side of the actuator component 100 to that from which droplets of fluid are ejected during use of the head 1.

As may be seen from Figure 1A, an inlet manifold chamber 255 and an outlet manifold chamber 260 are provided substantially within this manifold component 200. As may be seen from Figure 1A, in the particular example shown, the row of fluid chambers 10 is located on one side of the plane in which the traces 32 extend, with the inlet and outlet manifold chambers 255, 260 being located on the other side. Further, the inlet and outlet manifold chambers are spaced apart from one another in a depth direction D, which is perpendicular to the layering and row directions L, R.

The inlet manifold chamber 255 extends from a first end 256 (not visible in Figure 1A), at which it receives fluid, to a second end 257, which is fluidically connected in parallel to all of the inlet passageways 12 in the row. As a result, it is able to supply fluid to the row of inlet passageways 12 and, thereby, to the row of fluid chambers 10. In the particular example shown in Figure 1A, the inlet manifold chamber 255 extends generally parallel to the layering direction L from its first end 261 to its second end 262.

-4Similarly, the outlet manifold chamber 260 extends from a first end 261, which is fluidically connected in parallel to all of the outlet passageways 16 in the row so as to receive fluid therefrom (and thereby from the row of fluid chambers 10), to a second end 262, to which it conveys fluid. In the particular example shown in Figure 1A, the outlet manifold chamber 260 extends generally parallel to the layering direction L from its first end 261 to its second end 262.

As a result of the provision of inlet and outlet manifold chambers 255, 260, a droplet deposition head such as that shown in Figures 1A-1F may be configured to operate in a recirculation mode, whereby a continuous flow of fluid through the head is established during use.

In order to provide a high resolution head of compact construction that is capable of operating in a recirculation mode with high levels of reliability, the inventors have appreciated that a number of factors must be balanced.

Specifically, by forming the row of fluid chambers 10 within patterned layers, whose layering direction L is perpendicular to the row direction R, the chambers 10 in the row may be packed more densely, allowing the head 1 to have a large number of nozzles per inch, in other words, a high resolution. For instance, the actuator component may, for example, be fabricated using processes typically used to fabricate structures for Micro-ElectroMechanical Systems (MEMS). Further, conductive traces 32 that are disposed on one of such patterned layers may enable such a densely packed row (and specifically the actuating elements thereof) to be electrically connected to drive circuitry.

On the other hand, in order to provide suitably high levels of flow through the head 1 (such high levels of flow generally resulting in reliable droplet ejection, for example by removing detritus that might lodge within the nozzles 18) and/or in order to provide relatively balanced flow to each of the fluid chambers 10 (as significant differences in pressures and/or flow rates and/or flow velocities may lead to measureable differences in the droplets ejected by different chambers 10 within the row), the inlet and outlet manifold chambers 255, 260 should typically be relatively large.

However, it is challenging to provide such large inlet and outlet manifold chambers 255, 260 within a droplet deposition head while still achieving a compact construction for the head.

Furthermore, as the head construction becomes more compact, interference or “crosstalk” between neighbouring chambers 10 within the row tends to be exacerbated. Such crosstalk may, for example, result in greater variability of the velocity (in terms of magnitude and/or

-5direction) and/or the volume of the droplets ejected by the head, owing to such interference between neighbouring chambers.

Such “crosstalk” may result, in part, from residual energy within chambers following actuation being transferred through the structure of the actuator component 100 (e.g. through the walls 11 separating neighbouring chambers). The inventors have determined that head designs such as that shown in Figures 1A-1F, which have individual inlet and outlet passageways 12, 16 for each chamber 10, may guide the residual energy away from the chambers 110 being actuated, and may in consequence experience less interference or crosstalk between neighbouring chambers. This is found to be particularly the case where the length of each inlet and/or outlet passageway 12, 16 is at least 100pm, with further benefit potentially being provided where the length of each inlet and/or outlet passageway 12, 16 is at least 200pm.

The inventors envisage that where the inlet and outlet passageways 12, 16 are arranged such that they cross the plane in which the conductive traces 32 extend, passing between the conductive traces, the resulting head 1 may have a particularly compact construction, with relatively high resolution, while also enabling the inlet and outlet manifold chambers 255, 260 to be of a suitably large size.

In some embodiments, to enable the droplet deposition head 1 to operate in a recirculation mode, it may be provided with one or more fluid inlet ports and one or more fluid outlet ports for connection to a fluid supply system, with the first end 256 of the inlet manifold chamber 255 being fluidically connected to such inlet port(s) and the second end 262 of the outlet manifold chamber 260 being fluidically connected to such outlet port(s).

In a recirculation mode, the flow of fluid through the head 1 may, in some cases, be continuous. More particularly, there may be established a continuous flow of fluid through each of the chambers 10 in the row. This flow may, depending on the configuration of the fluid supply system (e.g. the fluid pressures applied at the fluid inlet and fluid outlet), continue even during droplet ejection, albeit potentially at a lower flow rate.

In more detail, such a fluid supply system may, for instance, be configured to apply a positive pressure to the fluid at the fluid inlet port and a negative pressure to the fluid at the fluid outlet port, thereby drawing fluid through the head.

Figure 1D illustrates the head 1 of Figures 1A-1F operating in a recirculation mode. The flow of fluid is shown in the drawing by means of thick arrows.

-6As is apparent, in such a recirculation mode, fluid may enter the inlet manifold at its first end 256 (not shown in the drawing) and flow through the inlet manifold chamber 255, generally in the layering direction L, to its second end 257.

As a result of the inlet manifold chamber 255 being fluidically connected in parallel to all of the inlet passageways 12 in the row, fluid then flows in parallel through each of these fluid inlet passageways 12. Fluid then flows (via the corresponding one of the flow restrictor passages 14a) through the corresponding one of the fluid chambers 10, past the respective one of the nozzles 18, and then through the corresponding one of the fluid outlet passageways 16 (via the corresponding one of the flow restrictor passages 14b). As a result of the outlet manifold chamber 260 being fluidically connected in parallel to all of the outlet passageways 16 in the row, fluid flows in parallel through each of the fluid outlet passageways 16 and then enters the outlet manifold chamber 260 through its first end 261. The fluid then flows through the outlet manifold chamber 260 (as with the inlet manifold chamber, generally in the layering direction L), to its second end 257.

Figures 1E and 1F, which are, respectively, views of cross-sections through the inlet manifold chamber 255 and the outlet manifold chamber 260 of the head 1 shown in Figures 1A-1F, show in further detail the flow patterns that may be present within the inlet and outlet manifold chambers 255, 260 when the head operates in a recirculation mode. It should be understood that, for the sake of clarity, Figures 1E and 1F show the head 1 as having only a relatively small number of fluid chambers 10; in practice the row would include a far larger number of chambers 10, such as 500, 1000 or more.

Turning first to Figure 1E, there is shown a cross-section taken through the inlet manifold chamber 255 in a plane extending in the layering and row directions L, R; as with Figure 1D, the flow of fluid through the head 1 is indicated by thick arrows.

As may be seen, the particular example of a manifold component 200 shown includes an inlet port 265 that is located adjacent to and is fluidically connected to the first end 256 of the inlet manifold chamber 255. In some examples, this inlet port 265 may be connected directly to the fluid supply system; in other examples, it might be connected to further components within the head, for instance further manifold components.

As is shown in Figure 1E, the fluid, having entered the inlet manifold chamber 255 at its first end 256, spreads out as it flows through the inlet manifold chamber 255, proceeding generally in the layering direction L.

-7As may be seen from Figure 1E, the extent, or width, of the inlet manifold chamber 255 in the row direction R increases from its first end 256 to its second end 257. This may, for example, assist in spreading the flow over the row of inlet passageways 12 in the row direction R. As may also be seen, the extent of the inlet manifold chamber 255 in the row direction R (its width) at its second end 257 is substantially equal to the extent of the row of fluid chambers 10 in the row direction R.

The inlet manifold chamber 255 may be shaped in such a way as to assist in providing fluid to the chambers 10 with balanced flow characteristics (for instance with substantially balanced pressures, and/or with balanced flow rates and/or with balanced velocities). Various measures may be taken in order to achieve such balanced flow characteristics.

As illustrated in Figure 1E, the inlet manifold chamber 255 may shaped such that, during use of the head 1, the streamlines of fluid flowing through the inlet manifold chamber 255 in the vicinity of the second end 257 are directed substantially parallel to the layering direction L. More particularly, as shown in the drawing, there may be a region 258 adjacent the second end 257, where the streamlines for the flow are directed substantially parallel to the layering direction L. This region may, for example, have an extent in the layering direction L that is at least 10% of that of the inlet manifold chamber 255 and may be at least 20% or at least 30% of its extent.

In the specific example shown in Figure 1E, for a portion of the inlet manifold chamber 255 adjacent the first end 256, the extent or width in the row direction R increases at a substantially constant rate with increasing distance towards the second end 257 in the layering direction L. As may also be seen, the sides of the inlet manifold chamber 255 in this widening portion are substantially parallel and planar (when viewed in a depth direction D that is perpendicular to the row and layering directions, R, L).

The inlet manifold chamber 255 may be shaped in such a way as to assist in providing fluid to the chambers 10 with balanced flow characteristics (for instance with substantially balanced pressures, and/or with balanced flow rates and/or with balanced velocities). However, straight sides are by no means essential to achieving such balanced flow characteristics and thus, in alternative constructions, the sides of inlet manifold chambers 255 may instead be convex, or concave, when viewed in a depth direction D (which is perpendicular to the row and layering directions R, L).

More generally, it should be noted that the extent of the inlet manifold chamber in the row direction R (its width) may increase from its first end 256 to its second end 257 (e.g. with

-8distance from its first end 256 opposite the layering direction L) in any suitable manner. The increase may, for example, be gradual and/or the width in the array direction may increase substantially monotonically with respect to distance along the layering direction L, as is the case in Figure 1E.

It should be noted that, in the specific droplet deposition head 1 of Figures 1A-1F, the extent of the inlet manifold chamber 255 in a direction D (its depth) that is perpendicular to the layering and row directions L, R, does not change significantly over the height of the inlet manifold chamber 255 in the layering direction. However, in other examples the extent or depth of the inlet manifold chamber 255 in this direction may taper from its first end towards its second end 257. For example, the depth of the widening inlet chamber in the depth direction D that is perpendicular to the layering and row directions L, R might decrease with increasing distance from its first end towards the second end 257 in a direction opposite the layering direction L. The depth and width of the inlet manifold chamber 255 might, for example, change in such a way that the cross-sectional area of the inlet manifold chamber 255 (in a plane perpendicular to the layering direction L) remains constant for substantially the whole of its height in the layering direction L.

Turning now to Figure 1F, there is shown a cross-section taken through the outlet manifold chamber 260 in a plane extending in the layering and row directions L, R; as with Figures 1D and 1E, the flow of fluid through the head 1 is indicated by thick arrows.

As may be seen, the particular example of a manifold component 200 shown includes an outlet port 267 that is located adjacent to and is fluidically connected to the second end 262 of the inlet manifold chamber 260. As with the inlet port 265, in some examples, the outlet port 267 may be connected directly to the fluid supply system, whereas in other examples, it may be connected to further components within the head, for instance further manifold components.

As is shown in Figure 1F, the fluid, having entered the outlet manifold chamber 260 at its first end 261, converges as it flows through the outlet manifold chamber 260, proceeding generally in the layering direction L.

As may be seen from Figure 1F, the extent of the outlet manifold chamber 260 in the row direction R (its width) decreases from its first end 261 to its second end 262. This may, for example, assist in concentrating the flow from the row of outlet passageways 16 as it proceeds towards the second end 262 of the outlet manifold chamber 260. As may also be

-9seen, the extent of the outlet manifold chamber 260 in the row direction R (its width) at its first end 261 is substantially equal to the extent of the row of fluid chambers 10 in the row direction R.

The outlet manifold chamber 260 may be shaped in such a way as to assist in providing fluid to the chambers 10 with balanced flow characteristics (for instance with substantially balanced pressures, and/or with balanced flow rates and/or with balanced velocities). Various measures may be taken in order to achieve such balanced flow characteristics.

As illustrated in Figure 1E, the outlet manifold chamber 260 may shaped such that, during use of the head 1, the streamlines of fluid flowing through the outlet manifold chamber 260 in the vicinity of the first end 261 are directed substantially parallel to the layering direction L. More particularly, as shown in the drawing, there may be a region 263 adjacent the first end 261, where the streamlines for the flow are directed substantially parallel to the layering direction L. This region may, for example, have an extent in the layering direction L that is at least 10% of that of the outlet manifold chamber 260.

In the specific example shown in Figure 1F, for a portion of the outlet manifold chamber 260 adjacent the second end 262, the width in the row direction R decreases at a substantially constant rate with increasing distance towards the second end 262 in the layering direction L. As may also be seen, the sides of the outlet manifold chamber 260 in this narrowing portion are substantially straight (when viewed in a depth direction D, which is perpendicular to the row and layering directions, R, L).

However, straight sides are by no means essential and thus, in alternative constructions, the sides of outlet manifold chambers 260 may instead be convex, or concave, when viewed in depth direction D, which is perpendicular to the row and layering directions R, L.

More generally, it should be noted that the extent of the outlet manifold chamber 260 in the row direction R (its width) may decrease from its first end 261 to its second end 262 (e.g. with distance in the layering direction L) in any suitable manner. The decrease may, for example, be gradual and/or the width in the array direction may decrease substantially monotonically with respect to distance in the layering direction L, as is the case in Figure 1F.

It should be noted that, in the specific droplet deposition head 1 of Figures 1A-1F, the extent of the outlet manifold chamber 260 in depth direction D (which is perpendicular to the layering and row directions L, R), does not change significantly over the height of the outlet manifold chamber 260 along the layering direction. However, in other examples the extent of the outlet manifold chamber 260 along this direction may taper from its second end 262

-10towards its first end 261. For example, the depth in the direction D of the widening outlet chamber that is perpendicular to the layering and row directions L, R might decrease with increasing distance from the second end 262 towards the first end 261 with respect to the layering direction L. The depth and width of the outlet manifold chamber 260 might, for example, change in such a way that the cross-sectional area of the outlet manifold chamber 260 (in a plane perpendicular to the layering direction L) remains constant for substantially the whole of its height in the layering direction L.

As is apparent from a comparison of Figure 1D with Figures 1E and 1F, the extent of the inlet manifold chamber 255 in depth direction D (which is perpendicular to the layering and row directions L, R)is substantially smaller than its extent in the row direction R (its width) and its extent in the layering direction L (its height). Similarly, the extent of the outlet manifold chamber 260 in depth direction D (which is perpendicular to the layering and row directions L, R)is substantially smaller than its extent in the row direction R (its width) and its extent in the layering direction (its height). Hence (or otherwise), the inlet and outlet manifold chambers 255, 260 may be described as extending generally in parallel planes, the normal of each such plane being parallel to depth direction D.

Returning now to Figure 1B, it is apparent from the drawing that each flow restrictor passage 14a, 14b presents a smaller cross-sectional area to flow as compared with the passages immediately adjacent to it. In the particular example shown, this is accomplished by each flow restrictor passage 14a, 14b having a smaller width perpendicular to the layering direction L as compared with the passages immediately adjacent to it. This approach to providing a reduced cross-section may be particularly appropriate as many techniques for forming patterned layers will provide greater control over features formed in the planes of the layers.

As is illustrated in Figure 1A, in the particular example embodiment shown in Figures 1A-1F each inlet passageway 12 extends through a number of layers within the actuator component 100, including: capping layer 40, wiring and passivation layers 30, membrane layer 20, and fluid chamber substrate layer 2. Similarly, each outlet passageway 16 extends through capping layer 40, wiring and passivation layers 30, membrane layer 20, and fluid chamber substrate layer 2.

Membrane layer 20 may therefore be considered as dividing each inlet passageway 12 into upper and lower portions (where the upper portion is that furthest from the nozzle layer 4 and the lower portion is that nearest to the nozzle layer 4) and each outlet passageway 16

-11into upper and lower respective portions (where, again, the upper portion 16 is that furthest from the nozzle layer 4 and the lower portion 16 is that nearest to the nozzle layer 4).

As is shown in Figure 1A, in the particular example embodiment shown in Figures 1A-1F each inlet passageway 12 is elongate in a direction that is generally parallel to the layering direction L. Similarly, each outlet passageway 16 is elongate in a direction generally parallel to the layering direction L.

In the specific example embodiment shown in Figures 1A-1F, the actuating element 22 is a piezoelectric actuating element and therefore includes a piezoelectric member 24; however, any type of actuating element that is actuable to cause the ejection of fluid from a chamber through a nozzle 18 corresponding to that chamber could be employed. For instance, other types of electromechanical actuating elements, such as electrostatic actuating elements, could be utilised. Indeed, the actuating elements need not be electromechanical: they might, for example, be thermal actuating elements, such as resistive elements.

Where, as in the example embodiment of Figures 1A-1F, an electromechanical actuating element 22 is employed, this may function by deforming a wall bounding the corresponding one of the chambers. Such deformation may in turn increase the pressure of the fluid within the chamber and thereby cause the ejection of droplets of fluid from the nozzle 18. In the particular example embodiment shown in Figures 1A-1F, the piezoelectric actuating element 22 functions by deforming membrane layer 20.

Where a deformable wall is used, such as the membrane provided by membrane layer 20, there may be a time-lag between the initial deformation of the wall and the increase in pressure that causes ejection. For instance, the wall might initially deform outwardly, causing a substantially instantaneous decrease in pressure, and then, a short time afterwards, move back to its undeformed position, causing a substantially instantaneous increase in pressure. In some cases, this returning motion may be suitably timed so as to coincide with the arrival in the vicinity of the nozzle of acoustic waves generated within the chamber by the initial outward movement of the wall. Thus, the acoustic waves may enhance the effect of the increase in pressure caused by the returning of the chamber wall to its undeformed position.

In further examples, the deformable wall might simply be actuated such that it initially deforms inwardly towards the chamber, thus causing a substantially instantaneous increase in pressure that causes ejection of a droplet.

-12In some cases, the surfaces of various features of the actuator component 100 may be coated with protective or functional materials, such as, for example, a suitable passivation or wetting material. For instance, such materials may be applied to the surfaces of those features that contact fluid during use, such as the inner surfaces of the inlet passageways 12, the outlet passageways 16, the fluid chambers 10 and/or the nozzles 18.

The fluid chamber substrate layer 2 shown in Figures 1A-1F may be formed of silicon (Si), and may for example be manufactured from a silicon wafer, whilst the features provided in the fluidic chamber substrate 2, including the fluid chambers 10, lower portions of inlet passageways 12(b), lower portions of outlet passageways 16(b), and flow restrictor passages 14a, 14b may be formed using any suitable fabrication process, e.g. an etching process, such as deep reactive ion etching (DRIE) or chemical etching. In some cases, the features of the fluid chamber substrate layer 2 may be formed from an additive process e.g. a chemical vapour deposition (CVD) technique (for example, plasma enhanced CVD (PECVD)), atomic layer deposition (ALD), or the features may be formed using a combination of etching and/or additive processes.

The nozzle layer 4 may comprise, for example, a metal (e.g. electroplated Ni), a semiconductor (e.g. silicon) an alloy, (e.g. stainless steel), a glass (e.g. SiO₂), a resin material or a polymer material (e.g. polyimide, SU8). In some cases, the nozzle layer 4 may be formed of the same material(s) as the fluid chamber substrate layer 2. Moreover, in some cases the features of the nozzle layer, including the nozzles 18, may be provided by the fluid chamber substrate layer 2, with the nozzle layer and fluid chamber substrate layer 2 being in effect combined into a single layer.

The nozzle layer 4 may, for example, have a thickness of between 10pm and 200pm (though for some applications a thickness outside this range may be appropriate).

The nozzles 18 may be formed in the nozzle layer 4 using any suitable process such as chemical etching, DRIE, or laser ablation.

In the droplet deposition head 1 illustrated in Figure 1A, the nozzle 18 is tapered such that its diameter decreases from its inlet to its outlet. The diameter of the nozzle outlet may, for example, be between 15pm and 100pm (though in some applications a diameter outside this range may be appropriate).

The taper angle of the nozzle 18 may be substantially constant, as shown in Figure 1A, or may vary between the inlet and the outlet. For instance, the nozzle 18 may have a greater taper angle at its inlet than at its outlet (or vice versa).

-13As noted above, each actuating element 22 is actuable to cause the ejection of fluid from the corresponding one of the chambers 10 through the corresponding one of the nozzles 18. In the particular example shown in Figures 1A-1F, each actuating element 22 functions by deforming membrane layer 20.

The membrane layer 20 may comprise any suitable material, such as, for example, a metal, an alloy, a dielectric material and/or a semiconductor material. Examples of suitable materials include silicon nitride (Si₃N₄), silicon dioxide (SiO₂), aluminium oxide (AI₂O₃), titanium dioxide (TiO₂), silicon (Si) or silicon carbide (SiC). The membrane layer 20 may be formed using any suitable technique, such as, for example, ALD, sputtering, electrochemical processes and/or a CVD technique. The apertures corresponding to the inlet and outlet passageways 12, 16 may be provided in the membrane 20 for example by forming an initial layer of material, in which apertures are then etched or cut to form the patterned membrane layer 20, or by forming the apertures (and, optionally, other patterning) simultaneously with the membrane layer 20 using a patterning/masking technique.

The membrane 20 may be any suitable thickness as required by an application, such as between 0.3pm and 10pm. The selection of a suitable thickness may balance, on the one hand, the drive voltage required to obtain a certain amount of deformation of the membrane (since, in general, a thicker and therefore more rigid membrane will require a greater drive voltage to achieve a specific amount of deformation) and, on the other hand, the reliability and performance parameters of the device (as thinner membranes may have shorter lifetimes, for example as they may be more susceptible to cracking).

While only one membrane layer is illustrated in Figures 1A-1F, it should be noted that multiple membrane layers could be employed in other designs. The various membrane layers might be formed from different materials, for example so as to provide the membrane with mechanical robustness to fatigue. In the simplest such case, the membrane may have a bilayer construction, but any suitable number of layers of different materials could be employed.

The membrane layer 20 faces the nozzle layer 4, with droplets being ejected in a direction normal to the plane of the membrane layer 20, that is to say, in a direction parallel to the layering direction L.

Actuation of each actuating element 22 may occur in response to the application of a drive waveform to the actuating element 22 in question. In the example embodiment of Figures

-141A-1F, such drive waveforms are received by two respective electrodes for each actuating element 22.

In more detail, actuating element 22 shown in Figures 1A and 1B includes a piezoelectric member 24, a bottom electrode 26 and a top electrode 28.

The piezoelectric member 24 may, for example, comprise lead zirconate titanate (PZT), but any suitable piezoelectric material may be used.

The piezoelectric member 24 shown in Figure 1A is generally planar, having opposing faces that extend normal to the layering direction L: the top electrode 28 is provided on one of these faces and the bottom electrode 26 is provided on the other. As may be seen from Figure 1A, the bottom electrode 26 is disposed between the piezoelectric member 24 and the membrane layer 20, whereas the top electrode 28 overlies the piezoelectric member and faces towards a recess 42 defined within capping layer 40.

The capping layer 40 may define a single recess 42 for groups of, or all of the actuating elements, or may define a respective recess 42 for each actuating element 22. Such recesses 42 may be sealed in a fluid-tight manner so as to prevent fluid within the fluid chambers 10 and inlet passageways 12 and outlet passageways 16 from entering.

The capping layer 40 shown in Figures 1A-1F may be formed of silicon (Si), and may for example be manufactured from a silicon wafer, whilst the features provided in the capping layer 40, including the recesses 42 and the upper portions of the inlet passageways 12 and of the outlet passageways 16 may be formed using any suitable fabrication process, e.g. an etching process, such as DRIE or chemical etching. In some cases, at least a subset of features of the capping layer 40 may be formed from an additive process, such as a CVD technique (e.g. PECVD), or ALD. In still other cases, the features may be formed using a combination of etching and/or additive processes.

The piezoelectric member 24 may be provided on the lower electrode 26 using any suitable fabrication technique. For example, a sol-gel deposition technique, sputtering and/or ALD may be used to deposit successive layers of piezoelectric material on the lower electrode 26 to form the piezoelectric element 24.

The lower electrode 26 and upper electrode 28 may comprise any suitable material, such as iridium (Ir), ruthenium (Ru), platinum (Pt), nickel (Ni) iridium oxide (lr₂O₃), lr₂O₃/lr, aluminium (Al) and/or gold (Au). The lower electrode 26 and upper electrode 28 may be formed using any suitable techniques, such as, for example, a sputtering technique.

-15In order to provide drive waveforms to the actuating elements 22, the actuator component 100 includes a number of electrical traces 32a, 32b. Such traces electrically connect the upper 28 and/or lower 26 electrodes to drive circuitry (not shown) and may, for example, extend in a plane having a normal in the layering direction L.

In the particular example embodiment shown in Figures 1A-1F, these traces are provided as part of the wiring and passivation layers 30 and are provided on the membrane layer 20. However, in other designs the traces may be provided on other layers within the actuator component.

In the particular design illustrated in Figure 1A, the upper electrodes 28 are electrically connected to electrical traces 32a, whereas the lower electrodes 26 are electrically connected to electrical traces 32b.

The electrical traces 32a/32b may, for example, have a thickness of between 0.01pm and 10pm, preferably between 0.1pm and 2pm, more preferably between 0.3pm and 0.7pm.

The electrical traces 32a/32b may be formed of any suitable conductive material, such as copper (Cu), gold (Ag), platinum (Pt), iridium (Ir), aluminium (Al), or titanium nitride (TiN).

At least one passivation layer 33b electrically isolates the traces 32b for the lower electrodes 26 from the traces 32a for the upper electrodes 28. At least one additional passivation layer 33a extends over the traces 32a for the upper electrodes 28 and may also extend over traces 32b for the lower electrodes 26.

Such passivation layers may protect the electrical traces 32a/32b from the environment to reduce oxidation of the electrical trace. In addition, or instead, they may protect the electrical traces 32a/32b from the droplet fluid during operation of the head, as contact between the traces and the fluid might cause short-circuiting to occur and/or may degrade the traces.

The passivation layers 33a/33b may comprise dielectric material so as to assist in electrically insulating the traces 32a/32b from each other.

The passivation layers 33a/33b may comprise any suitable material, such as SiO₂, AI₂O₃, Zr0₂, SiN, HfO₂.

Depending on the particular configuration of the traces 32a/32b and the passivation layers 33a/33b, the wiring and passivation layers 30 may further include electrical connections,

-16such as electrical vias (not shown), to electrically connect the electrical traces 32a/32b with the electrodes 26/28 through the passivation layers 33a/33b.

The wiring and passivation layers 30 may also include adhesion materials (not shown) to provide improved bonding between, for example, any of: the electrical traces 32a/32b, the passivation layers 33a/33b, the electrodes 26, 28 and the membrane 20.

The wiring and passivation layers 30 (e.g. the electrical traces/passivation material/adhesion material etc.) may be provided using any suitable fabrication technique such as, for example, a deposition/machining technique, e.g. sputtering, CVD, PECVD, ALD, laser ablation etc. Furthermore, any suitable patterning technique may be used as required, such as photolithographic techniques (e.g. providing a mask during sputtering and/or etching).

Reference is now directed to Figure 1C, which, as noted above, is a plan view of the actuator component 100 from the side to which the capping layer 40 is attached, with the capping layer 40 removed so as to show clearly an example of a suitable layout for the electrical traces 32 on membrane layer 20. In the illustrative configuration shown in Figure 1C, each actuating element 22 is electrically connected to two traces 32. In Figure 1C, the fluid chambers 10, flow restrictor passages 14a, 14b and nozzles 18, which are located on the far side of the membrane 20 in the view of Figure 1C, are depicted with dashed lines so as show clearly their orientations relative to the traces 32, inlet and outlet passageways 12,16 and the actuating elements 22.

As may be seen from Figure 1C, the traces 32 extend in a plane having a normal in the layering direction L. As is apparent from a comparison of Figure 1A with Figure 1C, the inlet passageways 12 cross this plane, with each inlet passageway 12 passing between conductive traces 32. As Figure 1C shows, one trace passes between each pair of neighbouring inlet passageways 12 (as the trace in question passes from one side of the row of inlet passageways 12 to the other). The outlet passageways 16 likewise cross this plane, with each outlet passageway 16 passing between conductive traces. As Figure 1C shows, one trace 32 passes between each pair of neighbouring outlet passageways 16 (as the trace in question passes from one side of the row of outlet passageways 16 to the other).

As is apparent from Figure 1B each pair of neighbouring inlet passageways 12 are separated by a corresponding wall 13; each pair of pair of neighbouring outlet passageways 16 are likewise separated by a corresponding wall 17. As may be appreciated from a comparison of Figure 1B with Figure 1C, for certain of the conductive traces 32a (in the particular example shown, those that are electrically connected to the upper electrodes 28) a

-17portion of each trace 32a is contained within a corresponding one of the inlet passageway walls 13. This may, for example, assist in electrically isolating those traces 32a from the fluid within the inlet passageways 12.

Similarly, for certain of the conductive traces 32b (in the particular example shown, those that are electrically connected to the lower electrodes 26) a portion of each trace 32b is contained within a corresponding one of the outlet passageway walls 17. This may, for example, assist in electrically isolating those traces 32b from the fluid within the outlet passageways 16.

Although in Figures 1A-1F the inlet passageways and outlet passageways are depicted as having rectangular cross-sections, it should be understood that the cross-section (specifically the cross-section taken perpendicular to the length of an inlet/outlet passageway) may take a variety of shapes. For example, the cross-section may be triangular shaped, square shaped, rectangular shaped, pentagonal shaped, hexagonal shaped, rhombus shaped, oval shaped or circular shaped.

Figure 2 illustrates a further example embodiment of a droplet deposition head 1. The example embodiment of Figure 2 includes a modified version of the actuator component 100 shown in Figures 1A-1F. More particularly, Figure 2 is a plan view of a cross-section taken along the length of one of the chambers 10 of the modified actuator component 100. As is apparent from a comparison of Figure 2 with Figure 1A, the fluidic architecture of the actuator component 100 of Figures 1A-1F has been modified.

In more detail, in the actuator component 100 of Figures 1A-1F, an end of each of the inlet passageways 12 opens to the exterior of the actuator component 100. Thus, each inlet passageway 12 is able to receive fluid directly from the second end 257 of the inlet manifold chamber 255, and convey it towards the fluid chambers 10. An end of each of the outlet passageways 16 similarly opens to the exterior of the actuator component 100. Thus, each outlet passageway 16 may convey fluid that it has received from the chambers 10 to exterior the actuator component, specifically to the first end 261 of outlet manifold chamber 260.

In contrast, in the actuator component 100 shown in Figure 2, there is formed an inlet port 15 that is fluidically connected at a first end to the exterior of the layers of the actuator component 100, so as to receive fluid therefrom (and, specifically, from the second end 257 of the inlet manifold chamber 255), and at a second end to each of the inlet passageways 12 within the row. The inlet port 15 is therefore elongate in the row direction R (into the page in Figure 2).

-18As may also be seen from Figure 2, there is formed in the actuator component 100 an outlet port 19 that is fluidically connected at a first end to each of the outlet passageways 16 within the row, so as to receive fluid therefrom, and at a second end to the exterior of the layers of the actuator component 100, so as to supply fluid thereto (specifically, to the first end 261 of outlet manifold chamber 260). The outlet port 19 is likewise elongate in the row direction R (into the page in Figure 2).

While in the particular design shown in Figure 2, the inlet port 15 and the outlet port 19 are formed in the capping layer 40, they could be formed in any suitable layer. For instance, an additional layer could be provided that overlies the capping layer 40, with the inlet port 15 and the outlet port 19 being provided substantially within this additional layer.

Further, while Figure 2 illustrates the inlet port 15 and the outlet port 19 as extending only part-way into the capping layer 40 in the layering direction L, in other embodiments either or both of the inlet port 15 and the outlet port 19 could extend through the entirety of the capping layer 40, for example all the way to the membrane layer 20.

While only one inlet port 15 is provided in the actuator component 100 shown in Figure 2, with this inlet port 15 being common to all the inlet passageways 12, in other designs a number of inlet ports 15 could be provided, with each being connected to a corresponding group of inlet passageways 12 so as to supply fluid thereto.

In addition or instead, a number of outlet ports 19 could be provided (rather than just one common outlet port 19, as in Figure 2) with each being connected to corresponding group of outlet passageways 16, so as to receive fluid therefrom.

Reference is now directed to Figure 3, which is a partially exploded perspective view of a droplet deposition head 1 according to a further example embodiment, with the manifold component 200 of the head 1 shown in cross-section so as to illustrate its interior features.

The droplet deposition head of Figure 3 has four rows of fluid chambers 10, which are provided by two actuator components 100(1), 100(2), with each of actuator component providing two rows of fluid chambers 10.

As may be seen from Figure 3, the manifold component 200 includes two substantially identical groups of inlet and outlet manifold chambers, each group including one inlet manifold chamber 255(1), 255(2) and two outlet manifold chambers 260(1)(i)-(ii), 260(2)(i)(ii), with the two groups being identified by respective labels (1) and (2). For instance, for the manifold chamber group with label (1), there is shown one common inlet manifold chamber

-19255(1), which is fluidically connected so as to supply fluid to two corresponding rows of fluid chambers of the actuator component 100(1), and two outlet manifold chambers 260(1 )(i)-(ii), each of which receives fluid from a respective one of these rows of fluid chambers. It should be appreciated that, so as to show the fluid pathways in detail, Figure 3 illustrates as solid objects the respective spaces within the common inlet manifold chamber 255(1) and the outlet manifold chambers 260(1)(i), 260(1 )(ii) of group (1), which are exposed by the crosssection through manifold component 200.

As is apparent from Figure 3, the inlet and outlet manifold chambers are inlet and outlet manifold chambers are arranged in an array that extends in depth direction D, which is perpendicular to the row and layering directions. As with the example embodiments of Figures 1A-1F and Figure 2, the inlet and outlet manifold chambers 255, 260 in Figure 3 may be described as extending generally in parallel planes, the normal of each such plane being parallel to depth direction D.

In the particular example shown in the drawing, the common inlet manifold chamber 255 for each group is provided with a respective inlet port 265(1), 265(2).

As is shown in Figure 3, a respective outlet manifold chamber 260(1)(i), 260(1)(ii), is provided for each row of fluid chambers of corresponding actuator component 100(1), with the suffixes (i) and (ii) identifying the specific row for a particular fluid path. In the particular example of a manifold component 200 shown in the drawing, an outlet combining duct 269(1) is fluidically connected to the two outlet manifold chambers 260(1 )(i), 260(1)(ii) within the same group, so as to combine the fluid received from the outlet manifold chambers and convey it to the corresponding outlet port 267(1) for the group in question.

As is also indicated in Figure 3, the actuator component 100(2) is fluidically connected to a second inlet/outlet manifold group suffixed (2) not shown in its entirety apart from its inlet port 265(2) and outlet port 267(2). The arrangement of two separate fluid paths to each of the actuator components 100(1) and 100(2) may, for instance, enable each of the common inlet manifold chambers 255 to receive a different droplet fluid such as, for example, a different colour of ink, where the head 1 is configured as a printhead. Where the head 1 is configured for use with several different types of droplet fluid, the fluid paths may be arranged such that the different types of fluid are separated from each other within the head; the suffixes (1) and (2) indicate the two separate fluid paths within the head 1 shown in Figure 3.

-20With respect to each actuator component 100(1), 100(2), each includes a common inlet port 15(1), 15(2) formed in its exterior surface. Each such common inlet port 15(1), 15(2) supplies fluid to two rows of fluid chambers 10. As illustrated in Figure 3, each such common inlet port 15(1), 15(2) may be elongate in the row direction R.

As is also shown in Figure 3, the exterior surface of each actuator component 100(1), 100(2) also has formed therein a respective outlet port 19(1)(i),19(1)(ii), 19(2)(i), 19(2)(ii) for each row of fluid chambers 10. As illustrated in Figure 3, each such outlet port 19(1 )(i), 19(1)(ii), 19(2)(i), 19(2)(ii) may be elongate in the row direction R.

Though not visible in Figure 3, it should be noted that the different rows of fluid chambers 10 may be offset relative to one another in the row direction R by a small amount, for instance, of the order of the nozzle spacing for each array.

Where N rows of fluid chambers are supplied with the same droplet fluid (e.g. the same colour of ink), this offset may, for example, be approximately 1/N times the nozzle spacing (or, potentially, M+1/N times the nozzle spacing, where M is an integer). Hence, or otherwise, the nozzles of the N rows may together provide an array of nozzles which, when viewed in depth direction D (perpendicular to the row and layering directions R, L) appears as a single array of nozzles, with neighbouring nozzles being spaced apart by a distance 1/N. The nozzles from the N rows may accordingly be interleaved with respect to the row direction R. Thus, the multiple arrays may provide the head 1 with a higher resolution (in the preceding example, N times higher) than a single array. In the particular example shown in Figure 3, for instance, the two rows of fluid chambers in each fluid path might be offset by ¹Λ the nozzle spacing.

It may be noted that the specific example of a manifold component 200 that is shown in Figure 3 is formed from a plurality of layers, each of which extends perpendicularly to the layering direction L. More particularly, the manifold component 200 includes four layers: a first layer 270, a second layer 272, a third layer 274 and a fourth layer 276 (which is a carrier layer 276).

As may be seen from Figure 3, the first layer 270 is mounted within the second lower manifold layer 272, with the second lower manifold layer 272 having two arms that cradle the first lower manifold layer 270. As may also be seen from the drawing, the manifold component 200 includes holes 252 that extend through the layers of the manifold component 200 at opposing ends. Each hole can receive a fastening means such as a screw, bolt, fastening rod etc. that fastens the layers together. In addition (or potentially

-21instead), the layers of the lower manifold component may be coupled by welding, glue bonding, etc.

While the example of a manifold component 200 shown in Figure 3 utilises common inlet manifold chambers, in other examples, common outlet manifold chambers might be employed instead of (or perhaps in addition to) common inlet manifold chambers. Similarly, common outlet ports might be employed instead of (or perhaps in addition to) common inlet ports.

Moreover, it should be understood that the provision of common inlet or outlet manifold chambers is by no means essential in order to supply fluid to multiple rows of fluid chambers: respective inlet and outlet manifold chambers for each row of fluid chambers may equally be employed.

Similarly, it should be understood that the provision of common inlet or outlet ports is not essential: respective inlet and outlet ports for each row of fluid chambers may equally be employed.

Attention is now directed to Figures 4A-4C, which show respective examples of actuator components 100 with fluid pathways designed to supply fluid to multiple rows of fluid chambers 10. In the particular examples shown, each actuator component 100 has two rows of fluid chambers 10(i), 10(ii) (with the suffixes (i) and (ii) identifying the particular row of fluid chambers); however, it should be understood that the same principles may be applied to actuator components with any suitable number of rows of fluid chambers 10.

Turning first to the example actuator component 100 shown in Figure 4A, there is formed in the exterior surface of the actuator component 100 a common inlet port 15, which supplies fluid to the two rows of fluid chambers 10(i), 10(ii). As may be seen from Figure 4A, the common inlet port 15 has a first end, which is provided on the exterior of the actuator component 100, that may be connected to a corresponding inlet manifold chamber 255. The second end of the common inlet port 15 shown in Figure 4A is fluidically connected to a row of common inlet passageways 12, which in turn supplies fluid to both of the rows 10(i), 10(ii) of fluid chambers within the actuator component 100.

The actuator component 100 shown in Figure 4A further includes a respective row of outlet passageways 16(i), 16(ii) for receiving droplet fluid from each of the rows of fluid chambers 10(i), 10(ii). Each row of outlet passageways 16(i), 16(ii) is in turn fluidically connected to a respective outlet port 19(i), 19(ii) that is formed in the exterior surface of the actuator component 100.

-22Turning next to the example actuator component 100 shown in Figure 4B, as with the actuator component 100 shown in Figure 4A, there is formed in the exterior surface of the actuator component 100 a common inlet port 15, which supplies fluid to the two rows of fluid chambers 10(i), 10(ii). However, in contrast to the actuator component 100 shown in Figure 4A, in the actuator component of Figure 4B, the common inlet port 15 is fluidically connected to two rows of inlet passageways 12(i), 12(ii), each of which supplies fluid to a respective one of the rows of fluid chambers 10(i), 10(ii).

As with the actuator component shown in Figure 4A, the actuator component of Figure 4B includes a respective row of outlet passageways 16(i), 16(ii) for receiving droplet fluid from each of the rows of fluid chambers 10(i), 10(ii). Again, each row of outlet passageways 16(i), 16(ii) is in turn fluidically connected to a respective outlet port 19(i), 19(ii) that is formed in the exterior surface of the actuator component 100.

Turning now to the example actuator component 100 shown in Figure 4C, there is provided a respective inlet port 15(i), 15(ii), row of inlet passageways 12(i), 12(ii), row of outlet passageways 16(i), 16(ii) and outlet port 19(i), 19(ii) for each row of fluid chambers 10(i), 10(ii). It should nonetheless be understood that the separate inlet ports 15(i), 15(ii) could be fluidically connected so as to receive fluid from a common inlet manifold chamber 255.

Attention is now directed to Figure 5, which illustrates a further example embodiment of a droplet deposition head 1 in like manner to Figure 3.

The droplet deposition head 1 shown in Figure 5 is of generally similar construction to that shown in Figure 3. However, in contrast to the droplet deposition head 1 of Figure 3, the droplet deposition head 1 of Figure 5 includes an actuator component 100 that provides four rows of fluid chambers. Accordingly, formed in the exterior surface of the actuator component 100 are two common inlet ports 15(1), 15(2), each of which receives fluid from a respective common fluid inlet manifold 255 and supplies fluid to a respective one of the rows of fluid chambers 10. A respective outlet port 19(1 )(i), 19(1 )(ii), 19(2)(i), 19(2)(ii) for each of the rows of fluid chambers is also formed in the exterior surface of the actuator component and supplies fluid to a respective outlet manifold chamber 260(1)(i), 260(1)(ii), 260(2)(i), 260(2)(11).

As is also shown in Figure 5, the actuator component 100 further includes a central connection region 83 and two side connection regions 81, 82. As is apparent from the drawing, the central connection region is located between the rows of chambers, whereas

-23each side connection region 81, 82 is located on the outer side (with respect to the row direction R) of a respective one of the outermost rows of chambers.

The traces 32 that provide electrical connection to the actuator elements 22 may extend to the side connection regions 81, 82 and to the central connection region 83 so that drive circuitry may be electrically connected to the traces at these connection regions 81, 82, 83. For instance, bond pads may be formed on the connection regions, with flexible cabling, printed circuit or the like being attached to the bond pads so as to provide electrical connection to the drive circuitry.

In some embodiments, the central connection region 83 may include one or more common electrical buses that may, for example, provide common voltage waveforms to a number of the actuator elements 22. For instance, a respective electrical bus for each row of fluid chambers may be provided, so that a common voltage waveform may be applied to each actuator element 22 of the row in question. More particularly, this common voltage waveform may be applied to the same one of the electrodes of each of actuator element 22 of the row in question (e.g. to the bottom electrode 26 of each actuator element 22, or the top electrode 28 of each actuator element 22).

Such common voltage waveforms may, for example, be generated in components located remotely from the droplet deposition head 1. This may reduce the amount of heat generated within the head 1 and therefore make thermal control of the head more straightforward.

Reference is now directed to Figure 6, which illustrates a suitable layout for the traces 32 on a layer (e.g. membrane layer 20) of the actuator component 100 shown in Figure 5. Figure 5 is a plan view of the actuator component 100 from the side to which the capping layer 40 is attached, with the capping layer 40 removed so as to show clearly the layout of the traces 32. A central connection region 83 and two side connection regions 81, 82 are shown clearly in the drawing.

Figure 6 indicates the rows of fluid chambers that belong to the first group, with suffix (1), and those that belong to the second group, with suffix (2). Particular rows within a group are identified by the suffixes (i) and (ii).

In the example layout of traces shown in Figure 6, a respective group of conductive traces is provided for each of row of fluid chambers. These are indicated in the drawing using like suffixes to the rows themselves. As is apparent from the drawing, all of these groups of conductive traces and provided on the same layer of the actuator component, specifically membrane layer 20 and extend in the same plane, which has a normal in layering direction

-24L. However, it should be understood that in other arrangements, the groups might extend in different planes (e.g. respective planes), each having a normal in the layering direction L and/or the groups might be formed on different layers of the actuator component 100.

As may be seen from Figure 6, the example layout includes a common electrical connection 35. As may also be seen form Figure 6, this common electrical connection 35 extends in row direction R, whereas the traces 32 extend generally in depth direction D, which is perpendicular to the row and layering directions R, L. Although not visible in the drawing, this common electrical connection 35 extends substantially the full length of the rows of fluid chambers R(1 )(ii), R(2)(i) it is disposed between.

In more detail, it should be noted that, for each row of fluid chambers R(1 )(i), R(1)(ii), R(2)(i), R(2)(ii), a first fraction of the group of traces for that row of fluid chambers, indicated in the drawing with suffix (b), is electrically connected to the common electrical connection 35. Traces belonging to the first fraction 32(1)(i)(b), 32(1)(ii)(b), 32(2)(i)(b), 32(2)(ii)(b) extend towards the interior of the actuator component 100 in a direction parallel to depth direction D.

As may also be seen from Figure 6, a second fraction of each group of traces 32(1)(i)(a), 32(1 )(ii)(a), 32(2)(i)(a), 32(2)(ii)(a), indicated in the drawing with suffix (a), extend in generally the opposite direction to the first fraction. Thus, they extend towards the exterior of the actuator component 100 in a direction parallel to the depth direction D. Each trace from the second fraction 32(1)(i)(a), 32(1)(ii)(a), 32(2)(i)(a), 32(2)(ii)(a) is individual electrically connected such that it can receive a respective drive voltage waveform from drive circuitry.

In the particular example shown in Figure 6, the lower electrode 26 of each actuating element 22 is connected to a trace from the corresponding first fraction 32(1)(i)(b), 32(1 )(ii)(b), 32(2)(i)(b), 32(2)(ii)(b), whereas the upper electrode 28 of each actuating element 22 is connected to a trace from the corresponding second fraction 32(1)(i)(a), 32(1 )(ii)(a), 32(2)(i)(a), 32(2)(ii)(a). However, in other examples the upper and lower electrodes could be connected in the opposite manner.

In the example shown in Figure 6, it will be noted that the actuator component 100 is shown as having respective rows of inlet and outlet passageways 12, 16 for each row of fluid chambers R(1)(i), R(1)(ii), R(2)(i), R(2)(ii). However, this is by no means essential and in other embodiments rows of common inlet passageways (for example as illustrated in Figure 4A) or rows of common outlet passageways could be utilised.

Furthermore, while in the example of Figure 6 only a single common electrical connection 35 is provided, it should be appreciated that multiple common electrical connections may be

-25utilised. Figure 7 illustrates an example layout in which a respective common electrical connection 35(1)(i)(b), 35(1)(ii)(b), 35(2)(i)(b), 35(2)(ii)(b) is provided for each row of fluid chambers R(1 )(i), R(1)(ii), R(2)(i), R(2)(ii). As before, a central connection region 83 and two side connection regions 81, 82 are shown clearly in the drawing.

It may be noted that, as in the example of Figure 6, Figure 7 shows the lower electrode 26 of each actuating element 22 as being connected to a trace from the corresponding first fraction 32(1)(i)(b), 32(1)(ii)(b), 32(2)(i)(b), 32(2)(ii)(b), with the upper electrode 28 of each actuating element 22 being shown connected to a trace from the corresponding second fraction 32(1)(i)(a), 32(1 )(ii)(a), 32(2)(i)(a), 32(2)(ii)(a). However, in other examples the upper and lower electrodes could be connected in the opposite manner.

The layout of traces shown in Figure 7 allows each row of fluid chambers to receive a respective common drive signal.

It should be appreciated that, in layouts such as those shown in Figures 6 and 7, electrical connection may be more straightforward, as traces that require individual electrical connection extend towards the outside of the actuator component 100, whereas the common connections (which require only a small number of connections) are provided centrally.

More generally, it should be understood that heads described above may be manufactured by: forming and patterning the patterned layers of the actuator component, so as to provide the actuator component; forming the manifold component(s); and then attaching the manifold component(s) to the actuator component, for example by bonding (e.g. using adhesive). The (or each) manifold component may be made by moulding (e.g. injection moulding) a number of layers and then assembling these, for example by bonding them together.

As stated above with regard to the example embodiment of Figure 3, it should be understood that the provision of common inlet or outlet manifold chambers is by no means essential in order to supply fluid to multiple rows of fluid chambers: respective inlet and outlet manifold chambers for each row of fluid chambers may equally be employed.

More generally, while the droplet deposition heads shown in Figures 1-5 include only a single manifold component, other droplet deposition heads may include a number of

-26manifold components. For instance, respective manifold components could provide the inlet manifold chamber and the outlet manifold chamber.

It should also be noted that the actuator components described above with reference to Figures 1-5 may, for example, be fabricated using processes typically used to fabricate structures for Micro-Electro-Mechanical Systems (MEMS). In such cases, the actuator components may be described as being MEMS actuator components (it being noted that this carries with it no implication as to the type of actuating element utilised: for instance, actuator components with thermal actuating elements are referred to within the art as MEMS actuator components regardless of the fact that they do not include electromechanical actuating elements).

Other examples and variations are contemplated within the scope of the appended claims.

It should be noted that the foregoing description is intended to provide a number of nonlimiting examples that assist the skilled reader’s understanding of the present invention and that demonstrate how the present invention may be implemented.

Claims

1. A droplet deposition head comprising:

An actuator component comprising:

a plurality of patterned layers, each layer extending in a plane having a normal in a layering direction, the layers being stacked one upon another in said layering direction;

A row of fluid chambers formed within said plurality of layers, the fluid chamber row extending in a row direction, which is substantially perpendicular to said layering direction, each fluid chamber being provided with a respective nozzle and a respective actuating element, which is actuable to cause the ejection of fluid from the chamber in question through the corresponding one of the nozzles;

A row of inlet passageways formed within said plurality of layers, the inlet passageway row extending in said row direction, each inlet passageway extending from a first end, where it receives fluid, to a second end, which is fluidically connected to a respective one of said fluid chambers so as to supply fluid thereto;

A row of outlet passageways formed within said plurality of layers, the outlet passageway row extending in said row direction, each outlet passageway extending from a first end, which is fluidically connected to a respective one of said fluid chambers so as receive fluid therefrom, to a second end, to which it conveys fluid; and

A plurality of conductive traces extending in a plane having a normal in said layering direction and being provided on one of said plurality of layers, the conductive traces providing at least part of the electrical connection between said actuating elements and drive circuitry; and

One or more manifold components, there being provided substantially within the manifold components:

an inlet manifold chamber, which extends from a first end, at which it receives fluid, to a second end, which is fluidically connected in parallel to substantially all of the inlet passageways in said row so as to supply fluid thereto and, thereby, to the row of fluid chambers; and an outlet manifold chamber, which extends from a first end, which is fluidically connected in parallel to substantially all of the outlet passageways in said row so as to receive fluid therefrom and thereby from the row of fluid chambers, to a second end, to which it conveys fluid;

wherein substantially all of said inlet and outlet passageways cross the plane in which said conductive traces extend, passing between said conductive traces.

2. The droplet deposition head of Claim 1, wherein the extent of the inlet manifold chamber in said row direction increases from its first end to its second end.

3. The droplet deposition head of Claim 1 or Claim 2, wherein the extent of the inlet manifold chamber in said row direction at its second end is substantially equal to the extent of the row of fluid chambers in said row direction.

4. The droplet deposition head of Claim 3, wherein the extent of the inlet manifold chamber in said layering direction is approximately equal to or greater than its extent in the row direction.

5. The droplet deposition head of Claim 3 or Claim 4, wherein the extent of the inlet manifold chamber in a direction perpendicular to said row direction and to said layering direction is substantially smaller than its extent in said row direction and its extent in said layering direction.

6. The droplet deposition head of any preceding claim, wherein the inlet manifold chamber extends generally parallel to said layering direction from said first end to said second end.

7. The droplet deposition head of any preceding claim, wherein the inlet manifold chamber is shaped such that, during use of the head, the streamlines of fluid flowing through the inlet manifold chamber in the vicinity of said second end are directed substantially parallel to said layering direction.

8. The droplet deposition head of any preceding claim, wherein the inlet manifold chamber is shaped such that, during use of the head, the streamlines of fluid flowing through the inlet manifold chamber in a region of the inlet manifold chamber adjacent the second end are directed substantially parallel to said layering direction;

wherein said region extends, in said layering direction, from said second end and has an extent in said layering direction that is at least 10%, preferably at least 20%, and more preferably at least 30%, of the extent of the inlet manifold chamber in the layering direction.

9. The droplet deposition head of any preceding claim, wherein the extent of the outlet manifold chamber in said row direction decreases from its first end to its second end

10. The droplet deposition head of any preceding claim, wherein the extent of the outlet manifold chamber in said row direction at its first end is substantially equal to the extent of the row of fluid chambers in said row direction.

11. The droplet deposition head of Claim 10, wherein the extent of the outlet manifold chamber in said layering direction is approximately equal to or greater than its extent in the row direction.

12. The droplet deposition head of Claim 10 or Claim 11, wherein the extent of the outlet manifold chamber in a direction perpendicular to said row direction and to said layering direction is substantially smaller than its extent in said row direction and its extent in said layering direction.

13. The droplet deposition head of any preceding claim, wherein the outlet manifold chamber extends generally parallel to said layering direction from said first end to said second end.

14. The droplet deposition head of any preceding claim, wherein the outlet manifold chamber is shaped such that, during use of the head, the streamlines of fluid flowing through the outlet manifold chamber in the vicinity of said first end are directed substantially parallel to said layering direction.

15. The droplet deposition head of any preceding claim, wherein the outlet manifold chamber is shaped such that, during use of the head, the streamlines of fluid flowing through the outlet manifold chamber in a region of the outlet manifold chamber adjacent the first end are directed substantially parallel to said layering direction;

wherein said region extends, in said layering direction, from said first end and has an extent in said layering direction that is at least 10% of the extent of the outlet manifold chamber in the layering direction.

16. The droplet deposition head of any preceding claim, wherein the actuator component is configured to eject droplets of fluid in said layering direction from a first side thereof and wherein said one or more manifold components are attached to a second, opposite side thereof.

17. The droplet deposition head of any preceding claim, wherein said row of fluid chambers is located on one side of said plane in which the conductive traces extend and said inlet and outlet manifold chambers are located on the other side of said plane.

18. The droplet deposition head of any preceding claim, wherein the first end of each inlet passageway is located on an exterior surface of said plurality of layers.

19. The droplet deposition head of any preceding claim, wherein the second end of each outlet passageway is located on an exterior surface of said plurality of layers.

20. The droplet deposition head of any one of claims 1 to 17, further comprising one or more inlet ports formed within said layers, the or each inlet port being fluidically connected at a first end to the exterior of said plurality of layers, so as to receive fluid therefrom, and at a second end to a number of the inlet passageways within the row, so as to supply fluid thereto.

21. The droplet deposition head of Claim 20, wherein the or each inlet port is elongate in said row direction.

22. The droplet deposition head of Claim 20 or Claim 21, comprising a single inlet port whose second end is fluidically connected to substantially all of the inlet passageways within the row, so as to supply fluid thereto.

23. The actuator component of any one of claims 1 to 17 or 20 to 22, further comprising one or more outlet ports formed within said layers, the or each outlet port being fluidically connected at a first end to a number of the outlet passageways within the row, so as to receive fluid therefrom, and at a second end to the exterior of said plurality of layers, so as to supply fluid thereto.

24. The actuator component of Claim 23, wherein the or each outlet port is elongate in said row direction.

25. The actuator component of Claim 23 or Claim 24, comprising a single outlet port whose first end is fluidically connected to substantially all of the inlet passageways within the row, so as to receive fluid therefrom.

26. The droplet deposition head of any preceding claim, wherein said inlet and said outlet manifold chambers extend generally in parallel planes, the normal of each of which is perpendicular to said row direction and to said layering direction.

27. The droplet deposition head of any preceding claim, wherein said inlet and said outlet manifold chambers are spaced apart from one another in a direction perpendicular to said layering direction and to said row direction.

28. The actuator component of any preceding claim, wherein each of said actuating elements is an electromechanical actuating element that is actuable to cause the ejection of fluid from the chamber in question through the corresponding one of the nozzles by deforming a wall bounding the chamber in question.

29. The droplet deposition head of Claim 28, wherein each of said electromechanical actuating elements is a piezoelectric actuating element.

30. The droplet deposition head of Claim 29, wherein each of the chamber walls that are deformed by the actuation of the piezoelectric actuating elements is provided by a deformable membrane.

31. The droplet deposition head of Claim 30, wherein one or more of said plurality of layers is a membrane layer, which provides said deformable membrane for each chamber.

32. The droplet deposition head of Claim 31, wherein said plurality of conductive traces are provided on said membrane layer(s).

33. The droplet deposition head of any preceding claim, wherein each pair of neighbouring inlet passageways within said row are separated by a corresponding wall provided by said plurality of layers, and wherein a portion of at least some of said conductive traces are contained within said inlet passageway walls, so as to be isolated from fluid within said inlet passageways.

34. The droplet deposition head of any preceding claim, wherein each pair of neighbouring outlet passageways within said row are separated by a corresponding wall provided by said plurality of layers, and wherein a portion of at least some of said conductive traces are contained within said outlet passageway walls, so as to be isolated from fluid within said outlet passageways.

35. The droplet deposition head of any preceding claim, wherein at least one conductive trace passes between each pair of neighbouring inlet passageways.

36. The droplet deposition head of any preceding claim, wherein at least one conductive trace passes between each pair of neighbouring outlet passageways.

37. The droplet deposition head of any preceding claim, wherein each inlet passageway within said row extends through one or more of said layers.

38. The droplet deposition head of any preceding claim, wherein each of said inlet passageways is elongate in said layering direction.

39. The droplet deposition head of any preceding claim, wherein each outlet passageway within said row extends through one or more of said layers.

40. The droplet deposition head of any preceding claim, wherein each of said outlet passageways is elongate in said layering direction.

41. The droplet deposition head of any preceding claim, wherein the actuator component comprises:

a plurality of like rows of fluid chambers, including said row of fluid chambers;

a plurality of like rows of inlet passageways, including said row of inlet passageways, each of said plurality of rows of inlet passageways supplying fluid to one or more of said rows of fluid chambers; and a plurality of like rows of outlet passageways, including said row of outlet passageways, each of said plurality of rows of outlet passageways receiving fluid from one or more of said rows of fluid chambers;

wherein there is provided substantially within said one or more manifold components:

a plurality of like inlet manifold chambers, including said inlet manifold chamber, each of said plurality of inlet manifold chambers supplying fluid to one or more of said rows of inlet passageways; and a plurality of like outlet manifold chambers, including said outlet manifold chamber, each of said plurality of outlet manifold chambers receiving fluid from one or more of said rows of outlet passageways.

42. The droplet deposition head of Claim 41, wherein said inlet and outlet manifold chambers are arranged in an array that extends in a direction perpendicular to said row direction and to said layering direction.

43. The droplet deposition head of Claim 41 or Claim 42, wherein said inlet and outlet manifold chambers extend generally in parallel planes, the normal of each of which is perpendicular to said row direction and to said layering direction.

44. The droplet deposition head of any one of claims 41 to 43, wherein at least some of said inlet manifold chambers are common inlet manifold chambers, whereby they are fluidically connected so as to supply fluid to two rows of fluid chambers.

45. The droplet deposition head of Claim 44, wherein at least some of said rows of inlet passageways are rows of common inlet passageways, each row of common inlet passageways being fluidically connected so as to supply fluid to two corresponding rows of fluid chambers.

46. The droplet deposition head of Claim 44, wherein each common inlet manifold chamber is fluidically connected to its two corresponding rows of fluid chambers via a common inlet port formed in the exterior of said plurality of layers.

47. The droplet deposition head of Claim 46, wherein each common inlet port is fluidically connected at a first end, which is provided on the exterior of said plurality of layers, to a corresponding one of said inlet manifold chambers so as to receive fluid therefrom, and at a second end to two rows of inlet passageways, each of which supplies fluid to a respective row of fluid chambers.

48. The droplet deposition head of Claim 46 or Claim 47, wherein each inlet port is elongate in said row direction.

49. The droplet deposition head of any one of claims 41 to 48, wherein all of said inlet manifold chambers are common inlet manifold chambers.

50. The droplet deposition head of any one of claims 41 to 48, wherein at least some of said outlet manifold chambers are common outlet manifold chambers, whereby they are fluidically connected so as to receive fluid from two rows of fluid chambers.

51. The droplet deposition head of Claim 50, wherein all of said outlet manifold chambers are common outlet manifold chambers, whereby they are fluidically connected so as to receive fluid from two rows of fluid chambers.

52. The droplet deposition head of Claim 50 or Claim 51, wherein at least some of said rows of outlet passageways are rows of common outlet passageways, each row of common outlet passageways being fluidically connected so as to receive fluid from two corresponding rows of fluid chambers.

53. The droplet deposition head of Claim 50 or Claim 51, wherein each common outlet manifold chamber is fluidically connected to its two corresponding rows of fluid chambers via a common outlet port formed in the exterior of said plurality of layers.

54. The droplet deposition head of Claim 53, wherein each common outlet port is fluidically connected at a first end to two corresponding rows of outlet passageways so as to receive fluid therefrom, each of which receives fluid from a respective row of fluid chambers, and at a second end, which is provided on the exterior of said plurality of layers, to a corresponding one of the outlet manifold chambers.

55. The droplet deposition head of Claim 52, wherein each outlet port is elongate in said row direction.

56. The droplet deposition head of any one of claims 41 to 55, wherein there is provided a respective group of conductive traces for each of said rows of fluid chambers, said plurality of conductive traces being one of said groups, each group of conductive traces extending in a corresponding plane having a normal in said layering direction and being provided on one of said plurality of layers.

57. The droplet deposition head of Claim 56, wherein all of said groups of conductive traces extend in the same plane and are provided on the same one of said plurality of layers.

58. The droplet deposition head of Claim 56 or Claim 57, wherein, for each row of fluid chambers, the inlet passageways and outlet passageways for that row of fluid chambers cross the plane in which the group of traces for that row of fluid chambers extends.

59. The droplet deposition head of any one of claims 56 to 58, further comprising one or more common electrical connections;

wherein, for each row of fluid chambers, a first fraction of the group of traces for that row of fluid chambers is electrically connected to a corresponding one of said one or more common electrical connections;

wherein, for each row of fluid chambers, a second fraction of the group of traces for that row of fluid chambers is individual electrically connected such that they can receive respective drive voltage waveforms from drive circuitry.

60. The droplet deposition head of Claim 59, wherein a single said common electrical connection is provided, with the first fraction of traces from all groups being electrically connected to said common electrical connection.

61. The droplet deposition head of Claim 59, wherein a respective common electrical connection is provided for each row of fluid chambers, with the first fraction of traces from the group for that row of fluid chambers being electrically connected to the common electrical connection corresponding to that row of fluid chambers.

62. The droplet deposition head of any one of claims 59 to 61, wherein each actuating element comprises a piezoelectric member, and first and second electrodes that apply voltage waveforms to the piezoelectric member so as to cause its deformation.

63. The droplet deposition head of Claim 62, wherein said first electrode is electrically connected to a trace from the first fraction of the corresponding group of traces and wherein said second electrode is electrically connected to a trace from the second fraction of the corresponding group of traces.

64. The droplet deposition head of any one of claims 59 to 63, wherein each common electrical connection is located between neighbouring rows of fluid chambers.

65. The droplet deposition head of Claim 64, wherein each common electrical connection extends, in the row direction, substantially the full length of the neighbouring rows of fluid chambers it is disposed between.

66. The droplet deposition head of any one of claims 59 to 65, wherein each common electrical connection extends generally in said row direction

67. The droplet deposition head of any one of claims 59 to 66, wherein each of said traces extends generally in a direction perpendicular to said row direction and to said layering direction.

68. The droplet deposition head of any one of claims 59 to 67, wherein all common electrical connections are located between the same two neighbouring rows of fluid chambers, preferably wherein said two neighbouring rows of fluid chambers are the innermost two rows of fluid chambers with respect to a depth direction, which is perpendicular to said row direction and to said layering direction.

69. The droplet deposition head of any one of claims 59 to 68, further comprising two side connection regions, which are located on opposite sides of the actuator component, spaced apart in a direction perpendicular to said layering direction and said row direction;

wherein each trace from a first fraction extends to a respective electrical connection that is provided on the side connection region nearmost the row of fluid chambers for the trace in question.

70. The droplet deposition head of Claim 69, wherein each of the side connection regions extends in said row direction.

71. The droplet deposition head of Claim 69 or Claim 70, wherein each of said side connection regions is provided on a respective surface on the outside of said actuator component, each of which preferably has a normal in said layering direction.

72. The droplet deposition head of any preceding claim, wherein each fluid chamber within said row is elongate in a chamber length direction, which is perpendicular to said row direction and preferably is perpendicular to said layering direction.

73. The droplet deposition head of Claim 72, wherein each nozzle is provided in a longitudinal side of the corresponding fluid chamber within the row.

74. The droplet deposition head of any preceding claim, wherein one of said plurality of layers is a nozzle layer, which provides each of said nozzles.

75. The droplet deposition head of any preceding claim, further comprising said drive circuitry.

76. A method of manufacturing a droplet deposition head according to any preceding claim, comprising:

forming and patterning the plurality of patterned layers of the actuator component, so as to provide said actuator component;

forming said one or more manifold components; and then attaching said one or more manifold components to said actuator component.

77. The method of Claim 76, wherein attaching said one or more manifold components to said actuator component comprises bonding said one or more manifold components to said actuator component.

78. The method of Claim 76 or Claim 77, wherein forming said one or more manifold components comprises:

moulding, preferably by injection moulding, a plurality of layers;

bonding said plurality of layers together to provide said one or more manifold components.

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Application No: GB 1616946.8