Droplet ejection head, manifold components therefor, and design methods - Patents.com

Abstract

1. A manifold component for a droplet ejection head, the manifold component comprising: a mounting portion for receiving an actuator component that provides one or more rows of fluid chambers, each chamber having at least one respective actuating element and at least one respective nozzle, the at least one actuating element for each chamber being operable to eject droplets of fluid in an ejection direction through a corresponding at least one nozzle, each row comprising: a mounting portion extending in the row direction; a manifold chamber extending from a first end to a second end and widening from the first end to the second end, the second end providing parallel fluid connection to at least a group of chambers in the one or more rows and located adjacent the mounting portion; and at least one port, each port opening into the manifold chamber at its first end, and at least a portion of the manifold chamber between the first end and the second end being shaped as a hyperbolic acoustic horn. [Selected Figure] Figure 1A

Description

[Technical field]

[0001] MANIFOLD COMPONENTS FOR DROP EJECTION HEADS FIELD OF THE DISCLOSURE The present invention relates to manifold components for droplet ejection heads, and related design methods, which may find particular beneficial application in printheads, such as inkjet printheads.

[0002] Droplet ejection heads are in widespread use today, whether for more traditional applications such as inkjet printing, or for 3D printing or other rapid prototyping techniques.

[0003] In recent years, inkjet printheads have been developed that can deposit ink directly onto ceramic tiles with high reliability and throughput, allowing the patterns on the tiles to be customized to a customer's exact specifications and reducing the need to stock every type of tile.

[0004] In other applications, the droplet ejection heads may be used to form elements such as color filters in LCD or OLED displays used in the manufacture of flat screen televisions.

[0005] Droplet ejection heads and their components continue to evolve and become specialized to suit new and / or increasingly challenging applications. Summary of the Invention

[0006] Aspects of the invention are set out in the accompanying independent claims and particular embodiments of the invention are set out in the accompanying dependent claims.

[0007] The following disclosure provides, in one aspect, a manifold component for a droplet ejection head, the manifold component comprising: a mounting for receiving an actuator component providing one or more rows of fluid chambers, each chamber comprising at least one respective actuating element and at least one respective nozzle, the at least one actuating element for each chamber being operable to eject droplets of fluid in an ejection direction through a corresponding at least one nozzle, each row extending in a row direction; a manifold chamber extending from a first end to a second end and widening from said first end to said second end, the second end providing a fluid connection in parallel to at least a group of chambers in said one or more rows and located adjacent said mounting portion; at least one port, each port opening at a first end into the manifold chamber; A manifold component is described in which at least a portion between a first end and a second end of a manifold chamber is shaped as a hyperbolic acoustic horn.

[0008] The following disclosure describes, in another aspect, a manifold component for a droplet ejection head, the manifold component comprising one or more manifold chambers and at least one port, a transition portion connecting one of the at least one port to a second portion of the one or more manifold chambers, the transition portion including a change in cross-sectional shape blending from a cross-sectional area of ​​the one port to a cross-sectional area of ​​the second portion of the one or more manifold chambers. [Brief description of the drawings]

[0009] The invention will now be described with reference to the drawings, which are merely representational and are not to scale.

[0010] [Figure 1A] FIG. 1A is a cross-sectional view of a manifold component according to a first embodiment of the present disclosure. [Figure 1B]FIG. 1B is an end view of the manifold component shown in FIG. 1A. [Figure 2A] FIG. 2A is a cross-sectional view of a manifold component according to another embodiment. [Figure 2B] FIG. 2B is an end view of the manifold component shown in FIG. 2A. [Figure 2C] FIG. 2C is a side view of the manifold components shown in FIGS. 2A and 2B. [Figure 3A] FIG. 3A is a cross-sectional view of a manifold component according to another embodiment having multiple horn-shaped portions. [Figure 3B] FIG. 3B is an end view of the manifold component shown in FIG. 3A. [Figure 4] FIG. 4 is a manifold component according to another embodiment. [Figure 5A] FIG. 5A is a cross-sectional view of a manifold component according to yet another embodiment having multiple horn-shaped portions. [Figure 5B] FIG. 5B is an end view of the manifold component shown in FIG. 5A. [Figure 5C] FIG. 5C is a side view of the manifold components shown in FIGS. 5A and 5B. [Figure 6A] FIG. 6A shows the fluid paths in the manifold components according to the first test design. [Figure 6B] FIG. 6B is a fluid path in a manifold component according to another embodiment having multiple horn-shaped portions. [Figure 6C] FIG. 6C is a comparison of the calculated performance of the manifold components of FIGS. 6A and 6B. [Figure 7A] FIG. 7A is a cutaway three-dimensional view of the fluid paths in a flow-through enabled manifold component according to another test design. [Figure 7B(a)] FIG. 7B(a) is a cutaway three-dimensional view of fluid paths in a manifold component according to another embodiment that is flow-through compliant and has multiple horn-shaped portions. [Figure 7B(b)]FIG. 7B(b) is a cross-sectional view of the manifold component depicted in FIG. 7B(a). [Figure 7B(c)] FIG. 7B(c) is a cross-sectional view of the manifold component 750 depicted in FIGS. 7B(a) and 7B(b). [Figure 7B(d)] FIG. 7B(d) is a cutaway three-dimensional view of a detail of the fluid path depicted in FIG. 7B(a). [Figure 7C] FIG. 7C compares the calculated reflection coefficients over a range of frequencies for a manifold component according to FIG. 7A and a manifold component according to FIG. 7B. [Figure 8] FIG. 8 is an extract from a print sample produced using a drop-on-demand inkjet printhead. [Figure 9(AC)] 9(AC) is a graph comparing drop velocity data generated using a printhead with a test manifold component according to FIG. 7A with drop velocity data generated using a printhead with a horn-shaped manifold component according to FIG. 7B. [Figure 10] FIG. 10 is a schematic diagram illustrating a method for designing a horn-shaped portion for a manifold component according to one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] SUMMARY OF THE DISCLOSURE Embodiments of the present disclosure generally relate to manifold components for droplet ejection heads.

[0012] Referring now to FIG. 1, a manifold component 50 according to a first exemplary embodiment is shown. More specifically, FIG. 1A is a cross-sectional view of the manifold component 50 according to the first embodiment of the present disclosure, and FIG. 1B is an end view of the manifold component 50 shown in FIG. 1A. The exemplary embodiment shown in FIG. 1A and FIG. 1B generally relates to a manifold component 50 for a droplet ejection head. The manifold component 50 has a mounting 80 for receiving an actuator component 150 that provides one or more rows of fluid chambers (not shown). Each such chamber comprises at least one respective actuating element, e.g., a piezoelectric actuating element, and at least one respective nozzle. In operation, each actuating element is operable to eject droplets of fluid through a corresponding nozzle in an ejection direction 505. Each of the rows of fluid chambers extends in a row direction 500, as indicated by the respective arrows in FIG. 1A and FIG. 1B. In the particular exemplary embodiment of FIG. 1A and FIG. 1B, the mounting 80 is a flat receiving surface.

[0013] As can be seen from FIG. 1A, a manifold chamber 55 is provided within the manifold component 50. The manifold chamber 55 extends from a first end 51 to a second end 52, widening from the first end 51 to the second end 52. In operation, fluid flowing within the manifold chamber 55 can be described as "fanning out" as it approaches the second end 52. The second end 52 provides a parallel fluid connection to at least a group of chambers in one or more rows within the actuator component 150, the second end 52 being located adjacent to the mounting portion 80. As can also be seen from FIG. 1A, the manifold component further includes a port 120, which opens into the manifold chamber 55 at its first end 51. In operation, the port 120 can supply fluid to the first end 51 of the manifold chamber 55, such that the port 120 can be said to be an inlet port and the manifold chamber 55 can be said to be an inlet manifold chamber. During operation, the fluid then passes through the inlet manifold chamber 55 from its first end 51 to its second end 52. The entire portion of the manifold chamber 55 between its first end 51 and second end 52 is shaped as a hyperbolic acoustic horn to aid in transmitting acoustic waves in a direction away from the corresponding group of chambers in the actuator component 150. This may be referred to as a "horn-shaped portion." As shown representatively in FIG. 1, the cross-sectional area of ​​the manifold chamber 55 may hyperbolically increase from the first end 51 to the second end 52 to form a hyperbolic acoustic horn therein. The hyperbolic increasing cross-sectional area of ​​the hyperbolic horn-shaped portion of the manifold chamber 55 may provide a low level of acoustic crosstalk between the fluid chambers of the actuator component 150 during operation. This may occur because the manifold chamber having a portion shaped as a hyperbolic acoustic horn may aid in transmitting acoustic waves (generated when one or more actuation elements are actuated) from the manifold chamber 55 to the fluid supply. This in turn may improve the fall velocity and volume profile of droplets of fluid ejected from the nozzle.

[0014] It has been calculated that improved acoustic performance can be expected when using manifold components similar to those described in connection with FIG. 1. Furthermore, experimentally based testing of alternative embodiments (described later) shows that improved print quality can result. This can be explained as follows: When an actuation element is actuated to eject a droplet of fluid in an ejection direction 505, an acoustic wave passes back from the actuator component 150 into the manifold chamber 55. The reflected wave returns to the actuator component 150 and can affect the behavior of the fluid in other fluid chambers in the row of actuators, resulting in non-uniform drop velocity and non-uniform drop volume, which can cause defects in the appearance of the printed image. Here, it is shown that transmitting the acoustic wave from the manifold chamber 55 through the port 120 into the rest of the fluid system improves the consistency of the drop velocity and volume of droplets ejected from the individual fluid chambers, which in turn improves the appearance of the printed image or product.

[0015] An acoustic horn similar to that shown in the embodiment of manifold component 50 depicted in Figure 1 includes a region of increasing cross-sectional area according to a hyperbolic equation connecting two cross-sectional areas A2 and A1, where A2 is the smaller area and A1 is the larger area. In the manifold component 50 depicted in Figure 1, A2 is the cross-sectional area at the first end 51 proximate the port 120 and A1 is the cross-sectional area at the second end 52 proximate the mounting portion 80. In the manifold component 50, the source of acoustic waves of interest is one or more of the fluid chambers in the actuator component 150. Thus, during operation, acoustic waves will emanate from any fluid chamber in which an actuating element is actuated into the manifold chamber 55, for example, traveling through area A1 toward area A2.

[0016] 1A, can be represented by equation (1), where A(x) is the calculated area of ​​area 56 at a given location as x increases from area A2 to area A1 along central path 515, where x=0 is the location of area A2. Such a region of increasing cross-sectional area connecting two different cross-sectional areas A2 and A1 is generally referred to as a hyperbolic horn, also called a hyperbolic-exponential horn or hypex horn.

[0017] Hypex horns are a general group of horns that are desired for their increased wavefront area. A(x)=A2[cosh(x / x_T)+T sinh(x / x_T)]^2 (1) where T is a parameter that sets the shape of the horn. In most practical applications, 0≦T≦1. x_T is the reference distance calculated as follows: x_T=c / (2πf_c) (2) where c is the speed of sound in the fluid and f_c is the cutoff frequency, the frequency below which most of the energy is reflected and above which most of the energy is transmitted.

[0018] Such equations can be used to design a hypex horn according to any of the embodiments described herein. It can be appreciated that depending on the desired operational capabilities of the droplet ejection head, different operating frequency ranges and acceptable cutoff frequencies may be required and can be designed and selected accordingly.

[0019] Thus, a manifold component 50 having a hyperbolically varying cross-sectional area can be described as follows: Manifold chamber 55 has a central passageway 515 that extends centrally through manifold chamber 55 from the center of area A2 adjacent first end 51 to the center of area A1 adjacent second end 52. The change in cross-sectional area at any given point along central passageway 515 is indicated by arrow 56 and is the area perpendicular to central passageway 515. In the embodiment shown in FIG. 1, central passageway 515 is parallel to discharge direction 505, although this is not a required feature. In a part shaped as a hyperbolic acoustic horn, the cross-sectional area of ​​area 56 varies as a hyperbolic function of the distance from area A2 along central passageway 515. In other words, the portion of the manifold chamber 55 shaped as a hyperbolic acoustic horn has a central passage 515 that extends centrally through the manifold chamber from the center of the first end 51 of the manifold chamber 55 to the center of the second end 52, and the area of ​​a cross section 56 taken perpendicular to the central passage 515 varies approximately as a hyperbolic function of the distance from the first end 51 along the central passage 515.

[0020] In some embodiments, the cross-sectional area of ​​the horn-shaped portion of the manifold chamber 55 increases according to an exponential function. As one skilled in the art would appreciate, an exponentially increasing cross-sectional area is a special case of a hyperbolic or hypex increasing cross-sectional area (with T=1), and the manifold chamber 55 operates as an exponential acoustic horn.

[0021] It may be appreciated that manufacturing constraints and manufacturing tolerance requirements of the actual product mean that the manifold chamber 55 may not have an exactly mathematically true hypex (hyperbolic or exponential profile) for the horn shaped portion. A horn shaped portion having a profile that is close to or substantially hyperbolic may further provide improved dispensing performance when used in the manifold chamber 55. Thus, terms such as "hyperbolic", "hyperbolic horn shaped portion", including simply "horn shaped", may be understood to encompass profiles that are substantially hyperbolic. For example, instead of having a smooth wall profile, a stepped horn shaped portion made of multiple stacked sections, each section having a discrete height in the dispensing direction 505, may provide improved dispensing performance when used in the manifold chamber 55. Such a profile may result when using 3D printing to build up the manifold chamber 55, for example, by depositing multiple layers. Molded components may, for example, allow for some shrinkage and warping during manufacturing that changes the profile of the manifold chamber 55 while still improving dispensing performance. In general, a certain amount of noise may be tolerated in equation (1) when generating a profile for the walls of manifold chamber 55 while still providing acceptable droplet ejection performance.

[0022] In other embodiments, the hyperbolic horn-shaped portion may not extend through the entire manifold chamber 55, in which case it can be understood that area A2 is adjacent to but not necessarily coincident with the first end 51 of the manifold chamber 55, and area A1 is adjacent to but not necessarily coincident with the second end 52 of the manifold chamber 55.

[0023] As can be seen from FIG. 1B, in this embodiment, the actuator component 150 is elongated such that its length in the column direction 500 is much greater than its depth in the depth direction 510. Thus, in some embodiments, it may be desirable for the second end 52 of the manifold chamber 55 to be defined by an elongated opening parallel to the column direction 500 (e.g., such that the opening has a major axis extending in the column direction 500 and a minor axis extending in the depth direction). This may allow for ready fluid connection from the manifold chamber 55 to the actuator component 150. In some embodiments, the opening of the manifold chamber 55 at the second end 52 may have points at both ends of the major axis that define the same angle 53 (see FIG. 1A) between the plane of the opening and the wall of the manifold chamber 55.

[0024] 1, in this embodiment, manifold component 50 and manifold chamber 55 are similarly elongated in shape, although this is by no means required. Such an arrangement may be preferred, for example, when manifold component 50 is part of an arrangement of multiple manifold components, such as to provide different colors for printing onto paper or fabric, or to allow for dense printing of a single color, as this shape allows for close packing of multiple manifold components.

[0025] 1, the actuator component 150 is rectangular and the manifold chamber 55 has an opening at its second end 52 that is rectangular in cross section, however, this is by no means limiting and other fluid chamber row arrangements and actuator and manifold component shapes are contemplated.

[0026] It can be readily appreciated that where the actuator component 150 is very long and thin, it may be advantageous to use an array of manifold chambers 55 arranged adjacent to one another in the column direction 500, such that, during operation, each acts as an inlet manifold chamber 55 to supply fluid to a portion of the actuator component 150. In such an arrangement, each individual manifold chamber 55 will feed at least one group of fluid chambers in one or more columns of fluid chambers in the actuator component 150. In some embodiments, the second end 52 of the manifold chamber 55 may provide a fluid connection in parallel to a corresponding one of the one or more columns of fluid chambers.

[0027]

[0023] Referring now to Figure 2, a manifold component 250 is shown in accordance with another exemplary embodiment. More specifically, Figure 2A is a cross-sectional view of the manifold component 250, Figure 2B is an end view of the manifold component 250 shown in Figure 2A, and Figure 2C is a side view of the manifold component 250 shown in Figures 2A and 2B. The embodiment shown in Figures 2A-2C is in many respects similar to that seen in Figure 1, and thus, where appropriate, like reference numbers have been used.

[0028] Unlike the embodiment shown in FIG. 1, the manifold component 250 depicted in FIG. 2 does not have a horn-shaped profile over the entire length of the manifold chamber 55. Instead, as seen in FIG. 2A, the manifold chamber 55 includes a horn-shaped portion 30, as well as an additional (non-horn-shaped) portion 20 located between the first end 51 and the horn-shaped portion 30. The horn-shaped portion 30 is a portion of the manifold chamber 55 having a hyperbolically increasing cross-sectional area. The horn-shaped portion begins at an area A2 that is offset from the first end 51 of the manifold chamber 55 by a distance 58. The horn-shaped portion 30 may be described as beginning at area A2 proximate the first end 51 and ending at area A1 proximate the second end 52. It should be understood that in an embodiment in which the hyperbolic portion begins at the first end 51, such as that depicted in FIG. 1, the area A2 and the first end 51 coincide and the additional portion 20 is not present.

[0029] Although the portion of the manifold chambers 55 that increases hyperbolically may be limited in part by the physical constraints of the wider droplet ejection head design, in some embodiments, the cross-sectional area of ​​at least one manifold chamber 55 may increase hyperbolically over a majority of the distance between the first end 51 and the second end 52. That is, the hyperbolic horn-shaped portion extends over at least a majority of the distance between the first end 51 and the second end 52 of the corresponding manifold chamber 55. More specifically, the cross-sectional area may increase hyperbolically over a distance that is a fraction of 0.6 to 0.9 of the distance between the first end 51 and the second end 52. That is, the hyperbolic horn-shaped portion may extend over 0.6 to 0.9 times the distance between the first end 51 and the second end 52 of the corresponding manifold chamber 55. In still other embodiments, the cross-sectional area of ​​the manifold chamber 55 may increase hyperbolically over the entire distance between the first end 51 and the second end 52 along the manifold chamber 55. That is, the entire manifold chamber 55 is a hyperbolic horn (as shown in the embodiment depicted in FIG. 1). The term "distance" in this context refers to the distance between the first end 51 and the second end 52 along the central path 515 of the manifold chamber 55. It may further be understood that in the embodiments described herein, the location of A2 and A1 within the manifold chamber 55 depends on the extent and location of the hyperbolic portion relative to the first end 51.

[0030] Similar to the embodiment illustrated in FIG. 1, the manifold component 250 of FIG. 2 also has an elongated actuator component 150 such that its length in the column direction 500 is greater than its depth in the depth direction 510 (see FIG. 2B). The manifold component 250 also has a manifold chamber 55 with an elongated opening parallel to the column direction 500 at the second end 52. The manifold component 250 differs from the manifold component 50 of FIG. 1 in that the cross-sectional area is elongated in the column direction 500 throughout the hyperbolic horn-shaped portion 30. In this case, the cross-sectional area may be defined as the area 56 where the area 56 is elongated. As seen in FIG. 2A, the angle 53 may be measured at both (shorter) ends of the elongated area 56 in the column direction 500. Area 56 is the portion of a plane that intersects the bounding wall of manifold chamber 55 at any given point between areas A2 and A1, such that the angle 53 between the wall of manifold chamber 55 and the plane of the cross section is equal at the intersection points at both ends of manifold chamber 55. In other words, manifold chamber 55 has at least two points at both ends of elongated shaped area 56, at least at second end 52, that define the same angle 53 with said manifold chamber 55 wall.

[0031] As can be seen from FIG. 2, the depth of the hyperbolic horn-shaped portion 30 in the depth direction 510 remains generally constant. As seen in FIGS. 2A and 2B, the depth direction 510 is perpendicular to the row direction 500 and the discharge direction 505. Because the depth of the horn-shaped portion 30 is generally constant, the hyperbolic change in cross-sectional area is primarily due to the increase in width 57 in the row direction 500 of the horn-shaped portion 30. As seen in FIG. 2A, the central path 515 has a section of the central path 315 that extends centrally through the horn-shaped portion 30 from area A2 to area A1. At each point on the central path 315, the width 57 is measured in a direction that is perpendicular to the central path 315 at that point and perpendicular to the depth direction 510. The width 57 generally varies according to a hyperbolic function with the distance from area A2 to area A1 along the central path 315.

[0032] As can be further seen from FIG. 2A, with respect to the embodiment of FIG. 1, there is a port 120 located on the opposite surface 81 of the manifold component 250 relative to the mounting portion 80 in the discharge direction 505. In this embodiment, the port 120 has a circular cross-sectional area to allow for ready connection to a fluid supply system. Similarly, the first end 51 of the manifold chamber 55 has a circular cross-sectional area. As previously mentioned, the second portion 30 of the manifold chamber 55 can have a generally constant depth in the depth direction 510 and thus can also be elongated along the entire central passage 315. This means that the change in cross-sectional shape from circular to elongated occurs within the portion 20 of the manifold chamber 55, and the portion 20 is not a hyperbolic acoustic horn. In some embodiments, the portion 20 can be limited within the portion 20 such that the manifold chamber 55 can have a generally constant depth in the row direction 500 and in the depth direction 510 perpendicular to the discharge direction 505 for at least a majority of its extent in the discharge direction 505. As can be seen from Figures 2B and 2C, another major difference with respect to the embodiment of Figure 1 is that manifold component 250 of Figure 2 has two manifold chambers, manifold chambers 55 and 60, whereas manifold component 50 of Figure 1 has only a single manifold chamber 55. As can be seen from Figure 2C, manifold chamber 60 is offset from manifold chamber 55, such that the two are adjacent to each other in the depth direction 510. Furthermore, in this embodiment, the geometry of manifold chamber 60 is identical to that of manifold chamber 55, although these are by no means essential features and other arrangements and geometries of manifold chambers are envisioned. Thus, in this implementation, portions 25 (which may be referred to herein as "transition portions") and portions 35 of manifold chamber 60 are of the same geometry as portions 20 and 30, respectively, of manifold chamber 55. Additionally, the horn-shaped portion 35 begins at an area A 2 that is offset from a first end 61 of the manifold chamber 60 by a distance 58 , and ends at a second end 62 of the manifold chamber 60 .

[0033] As can be further seen from FIG. 2C, in contrast to the embodiment shown in FIG. 1, the manifold component 250 of FIGS. 2A-2C includes two ports 120 and 220, whereas the manifold component 50 of FIG. 1 has only a single port 120. In the particular embodiment shown, they are located on surface 81, although it should be understood that this location is by no means essential. In operation, when the ports 120, 220 are fluidly connected to a suitable fluid supply, the manifold component 250 shown in FIGS. 2A-2C may operate in a so-called "flow-through" mode such that, in operation, droplet fluid flows continuously from the port 120, through the manifold chamber 55, the actuator component 150, the manifold chamber 60, and into the port 220, such that the port 120, the manifold chamber 55, the actuator component 150, the manifold chamber 60, and the port 220 may be fluidly connected in series in that order. In operation, a portion of the fluid flowing through selected fluid chambers in the actuator component 150 may be ejected from the respective nozzles of those fluid chambers, while the remaining portion of the fluid continues through the individual fluid chambers, through the manifold chamber 60, and to the port 220. In such an embodiment, the manifold chamber 55 is configured as an inlet manifold chamber, and the corresponding port 120 is configured as an inlet port that supplies fluid to the first end 51 of the inlet manifold chamber 55 in operation. In operation, the second end 52 of the inlet manifold chamber 55 supplies fluid in parallel to each chamber in the corresponding group of fluid chambers in the actuator component 150. Furthermore, in such an embodiment, the manifold chamber 60 is configured as an outlet manifold chamber, and the corresponding port 220 is configured as an outlet port that receives fluid from the first end 61 of the respective outlet manifold chamber 60 in operation. In operation, the second end 62 of the outlet manifold chamber 60 receives fluid in parallel from each chamber in the corresponding group of fluid chambers in the actuator component 150.

[0034] In an alternative arrangement, during operation, fluid can be supplied to actuator component 150 from both ports 120 and 220, whereby the droplet ejection head may be considered to operate in a non-through flow mode, with manifold chambers 55 and 60 both being inlet manifold chambers and ports 120, 200 both operating as inlet ports.

[0035] In the embodiment depicted in FIG. 2, the central path 515 is a straight line parallel to the ejection direction 505 due to the geometry of the depicted design. In other embodiments, the central path 515 may not be a straight line, but may follow a curved or serpentine path, or any other path defined by the shape of the manifold chambers 55, 60. The manifold chambers may be shaped in such a manner, for example, as a result of physical constraints elsewhere in the droplet ejection head, or to allow for ready connection to a fluid supply. In such cases, for example, it may be appropriate to offset the port 120 and / or the port 220 from the center of the manifold component 250 in the array direction 500, or even to place the port on one of the sides 82, 83 of the manifold component 250. In these cases, the central path 515 may follow a different path at an angle to the ejection direction 505, depending on, for example, the shape of the manifold chambers 55, 60. In some embodiments, the central passage 515 that runs centrally through the manifold chamber from the center of the first end 51 to the center of the second end 52 may not be parallel to the discharge direction 505 along part of its length. It may be desirable to ensure that the central passage 515 runs generally parallel to the discharge direction 505 at the second end 52 of the manifold chamber to improve fluid performance by providing the actuator component 150 with fluid flowing in a preferred direction. As can be readily appreciated, other shapes of the manifold chambers 55, 60 and thus the central passage 515 are envisioned.

[0036] Referring now to FIG. 3, a manifold component 350 according to another exemplary embodiment is shown. More specifically, FIG. 3A is a cross-sectional view of the manifold component 350, and FIG. 3B is an end view of the manifold component 350 shown in FIG. 3A. Considering FIG. 3A, it is clear that the manifold component 350 in this embodiment differs from the previous two embodiments in that it comprises multiple hyperbolic horn-shaped portions 30 (x, y, z) arranged side-by-side in an array. Such a design may be suitable, for example, when the actuator component 150 is long in the row direction 500, and a single horn-shaped portion covering the entire actuator component in the row direction 500 may be too large in the ejection direction 505 to be practical. By using multiple hyperbolic horn-shaped portions, the height of the manifold chamber 55 may be reduced, producing a more compact droplet ejection head. For example, it can be seen from FIG. 3A that the height in the discharge direction 505 from the first end 51 to the second end 52 of the manifold chamber 55 is relatively equal to, but smaller than, the extent in the column direction 500 of the actuator components 150, desirably resulting in a compact arrangement.

[0037] As can be seen from FIG. 3A, the hyperbolic horn-shaped portions 30(x,y,z) are arranged side-by-side in the array, thereby adjacent to one another in the row direction 500. The horn-shaped portions 30(x,y,z) each have a respective central path 315(x,y,z) split off from a central path 515, and have a respective area 316(x,y,z) perpendicular to the respective central path 315(x,y,z). It can be seen that the areas 316(x,y,z) of the horn-shaped portions 30(x,y,z) increase substantially hyperbolically along the respective central paths 315(x,y,z) from area A2(x,y,z) to area A1(x,y,z). Like the embodiment shown in FIG. 2, the embodiment of FIG. 3 includes a hyperbolic portion that does not begin at the first end 51 of the manifold chamber 55. Suitable spatial offsets 58(x,y,z) may split the central path 515 to form respective central paths 315(x,y,z). It should be appreciated that due to design constraints, the offsets 58(x,y,z) may not be the same as one another, but rather may be determined according to the shape, location, orientation, etc. of the path from the first end 51 to each of the horn-shaped portions 30(x,y,z) and / or their respective central paths 315(x,y,z), and / or their respective areas A2(x,y,z). In practice, it may be appreciated that the hyperbolic equation of each horn-shaped profile may be more readily determined by individually setting x=0 for each located at the center of the respective area A2(x,y,z).

[0038] The cross-sectional area of ​​each horn-shaped portion 30(x,y,z) may be defined as follows: The hyperbolic acoustic horns may each have a corresponding central path 315(x,y,z) that extends centrally through the portion 30(x,y,z) from the center of area A2(x,y,z) to the center of area A1(x,y,z). At each point along the central path 315(x,y,z), a corresponding cross-sectional area 316(x,y,z) is defined that is in a plane perpendicular to the central path 315(x,y,z) and bounded by the walls of the hyperbolic acoustic horn, which may be a portion of the inner surface of the manifold chamber 55 and one side of one of the plurality of walls 70(i,ii) or two sides of two opposing walls of the plurality of walls 70(i,ii). The cross-sectional area of ​​area 316(x, y, z) varies approximately as a hyperbolic function of the distance from area A2(x, y, z) along central path 315(x, y, z).

[0039] As can also be seen from Figure 3A, adjacent horn-shaped portions 30(x,y) are separated by corresponding walls 70(i) located within the manifold chamber 55, and similarly adjacent horn-shaped portions 30(y,z) are separated by corresponding walls 70(ii) also located within the manifold chamber 55. As is apparent from Figure 3A, each of the walls 70(i,ii) extends over only a portion of the distance between the first end 51 and the second end 52 of the manifold chamber 55. The horn-shaped portions 30(x,y,z) comprise first and second sides (701-703)(i) and (ii), which are spaced apart in the row direction 500, and wherein the sides 701-703(i,ii) are substantially concave. A first side (701-703)(i) and a second side (701-703)(ii) are formed between the edges of the walls 70(i) and 70(ii) and the sides of the manifold chamber 55, whereby the first side 701(i) and the second side 701(ii) bound the horn shaped portion 30(x), the first side 702(i) and the second side 702(ii) bound the horn shaped portion 30(y), and the first side 703(i) and the second side 703(ii) bound the horn shaped portion 30(z). It can be appreciated that manufacturing constraints of a real product and manufacturing tolerance requirements mean that the horn shaped portion 30(x,y,z) may not have a mathematically true hyperbolic or exponential profile. For example, while walls 70(i,ii) are depicted as having sharp or pointed ends, it should be understood that this is purely representative and in practice the ends may be, for example, blunted or chamfered to facilitate manufacturing. Profiles or shapes that approach or are substantially hyperbolic or vary hyperbolically may still provide desirable printing performance when used, for example, in the horn-shaped portion 30(x,y,z) of manifold component 350 for a drop-on-demand printhead. For example, for manufacturing reasons, design constraints may limit walls 70(i,ii) to not be able to be less than a certain thickness, for example, 400 micrometers, and fillets or other smoothing features may be required at the tips of the walls.

[0040] 3A includes two walls 70(i, ii) and three horn-shaped portions 30(x, y, z), it should be understood that this is by no means required and alternative embodiments may include any suitable number of horn-shaped portions and corresponding dividing walls. In other embodiments, it may be desirable for fluidic reasons to offset the multiple horn-shaped portions by varying the position of the walls in the discharge direction 505 or other suitable arrangement to aid in smooth fluid flow from the first portion 20 to the multiple horn-shaped portions.

[0041] In the embodiment depicted in FIG. 3A, the walls 70(i, ii) are curved in an elongated manner and suitably shaped to provide a suitable hyperbolic profile to the horn-shaped portion 30(x, y, z) between areas A2(x, y, z) and A1(x, y, z). A manifold component 350 featuring such walls 70(i, ii) may be manufactured, for example, using 3D printing techniques, since using this method to manufacture such thin internal features may be easier compared to traditional casting, molding, or machining techniques. 3D printed components may also be easily made without seams and fluid tight seals, reducing leakage issues in the droplet ejection head. However, while the use of thin walls has been described to partition the horn-shaped manifold 30(x, y, z), other embodiments may instead use much wider walls or other physical features, and manufacturing techniques may include, for example, forming several separate components and joining them in any suitable manner to form a single fluid-tight manifold component 350.

[0042] As can be seen from FIG. 3A, each of the horn-shaped portions 30(x, y, z) is positioned to overlap a section of the second end 52 of the manifold chamber 55 in the column direction 500. In operation, each horn-shaped portion 30(x, y, z) preferentially provides a fluid connection in parallel to a respective group of chambers in one or more columns in the actuator component 150. In this embodiment, the horn-shaped portion divides the second end 52 into three equal sections. For example, if there are 300 fluid chambers in the column direction 500, each of the horn-shaped portions 30(x, y, z) in operation primarily supplies fluid to a group of 100 fluid chambers that are most closely adjacent to their location. During operation, the number of fluid chambers supplied by each horn-shaped portion 30(x,y,z) may not be exactly 100, and there may be some overlap near the location of walls 70(i,ii), since walls 70(i,ii) do not extend into slot 201 and some fluid may mix therein. It should be further understood that 300 fluid chambers is just one example, and that in some embodiments there may be a fewer or much greater number of fluid chambers.

[0043] It should be understood that in other embodiments, there may be any number of horn-shaped portions. It may further be understood that in designs with multiple horn-shaped portions, they are not necessarily identical. For example, the horn-shaped portions may be of different sizes to divide the second end 52 into equal or unequal sections, and thus the horn-shaped portions may feed equal or unequal sized groups of fluid chambers. As another example, multiple non-identical horn-shaped portions may be used to account for asymmetries in the manifold chamber 55. For example, as seen in FIG. 3A, the port 120 is located on the surface 81 at a position offset in the column direction 500 from the center of the manifold component 350 (unlike the embodiment of FIGS. 1 and 2). This is by no means required, but may be preferred in some embodiments for ease of connection to other components, such as fluid supplies. As a result, as can also be seen in FIG. 3A, the manifold chamber 55 connecting the port 120 to the actuator component 150 is asymmetric, and accordingly, the horn-shaped portions 30 (x, y, z) are shaped to be non-identical.

[0044] The manifold component 350 of FIG. 3 is similar to the embodiment depicted in FIG. 1 in that it includes a single manifold chamber 55. However, it is similar to the embodiment of FIG. 2 in that it includes a manifold chamber 55 that is divided into a (non-horn shaped) portion 20(1) proximate the port 120 and a horn shaped portion 30 proximate the actuator component 150. With respect to the manifold component 250 of FIG. 2, the embodiment depicted in FIG. 3 includes a change in cross-sectional shape from circular, which is aligned with the port 120, to elongated, which is aligned with the actuator component 150 in portion 20(1). Additionally, with respect to the embodiment depicted in FIG. 2, the manifold component 350 of FIG. 3 includes a horn shaped portion 30(x, y, z) that has an elongated cross-sectional area in the column direction 500.

[0045] It can further be seen in FIG. 3A that the manifold component 350 comprises two parts, a first manifold section 100 and a second manifold section 200, that are joined together, where the mounting 80 is located on the lower surface of the second manifold section 200 in the discharge direction 505. The actuator component 150 is mounted on the mounting 80. This is by no means a required feature, but in some embodiments may be useful to help securely connect the actuator component 150 to the manifold component 350, or to improve the lifespan of the actuator component 150, or to improve the assembly process. For example, if the first manifold section 100 is made from a material such as a resin or thermosetting plastic, or a plastic / fiber composite, for reasons of ease or cost of manufacture, it may have different thermal properties than the actuator component 150, which may be made primarily from silicon or piezoceramic materials. The second manifold section 200 may be made of a material, such as a ceramic or metal, that more closely matches the thermal properties of the actuator component 150 than the first manifold section 100, and may reduce stresses induced in the actuator component 150 during assembly or operation.

[0046] 3A also shows that second manifold section 200 has slot 20(2) therein fluidly connecting horn-shaped portion 30(x,y,z) to second end 52 of manifold chamber 55 and thus actuator component 150. It can be understood that such second manifold section 200 is by no means a required feature and that in many embodiments suitable thermal matching can be contained within a single manifold component as depicted in FIGS. 1 and 2 and / or within actuator component 150.

[0047] As can also be seen from FIG. 3A, the area A1(x, y, z) and the second end 52 do not coincide. The slot 20(2) is a non-hyperbolic portion that connects the horn-shaped portion 30(x, y, z) to the second end 52 of the manifold chamber 55. In operation, the slot can allow some fluid mixing between the fluid exiting the horn-shaped portion and the fluid entering the actuator component 150, and can also act as a flow straightener, aligning and directing the fluid flow to be more closely parallel to the discharge direction 505 at the second end 52 in operation. It can also act to flatten the velocity profile along the row direction 500 so that the fluid supplied to the actuator component 150 has a more uniform velocity.

[0048] FIG. 4 illustrates a manifold component according to another embodiment. Specifically, FIG. 4 depicts a manifold component 450 having a manifold chamber 55 with a hierarchical arrangement of multiple hyperbolic horn-shaped portions 30(1)(i,ii), 30(2)(i-vi), and 30(3)(i-xii) that are divided by multiple walls 70(i,ii), 71(i-iii), and 72(i-vi), where not all of the walls extend throughout the portions 30, unlike the embodiment depicted in FIG. 3. Such a design may be suitable, for example, when the actuator component 150 is long in the column direction 500 and there is a requirement for multiple horn-shaped portions due to spatial constraints in the discharge direction 505. Another reason for having a hierarchical arrangement of multiple hyperbolic horn-shaped portions may be when there is not enough room at the apex of the manifold chamber 55 proximate the first end 51 to fit the multiple walls due to manufacturing constraints such as minimum wall thickness. This constraint can be overcome by introducing an increasing number of walls as the manifold chamber 55 widens in the discharge direction 505. Another reason for staggering the introduction of walls may be, for example, when the fluidic design requires a minimum gap in the array direction 500 between walls proximate the first end 51. This may be desirable to ensure that there is smooth, unimpeded fluid flow into the horn-shaped portion, but there are spatial constraints on the length in the array direction 500 of the first end 51.

[0049] It can be seen from FIG. 4 that some of the walls 70(i,ii) extend through all three of the hierarchical portions 30(1)(i,ii), 30(2)(i-vi), and 30(3)(i-xii), some (walls 71(i-iii)) extend through two of the hierarchical portions, and the remaining portions (walls 72(i-vi)) are only in the final hierarchical portion. Such an arrangement may make design and manufacture easier, but is by no means required. In some embodiments, different arrangements of walls may be used to separate the hierarchical portions, for example, an arrangement is envisioned in which each wall extends only a portion of the distance from the first end 51 to the second end 52 of the corresponding manifold chamber 55.

[0050] The manifold component 450 depicted in FIG. 4 comprising an array of a plurality of the side-by-side horn-shaped portions includes a first array of side-by-side horn-shaped portions 30(1)(i, ii) adjacent to the first end 51 of the inlet manifold chamber 55 and a last array of horn-shaped portions 30(3)(i-xii) adjacent to the second end 52 of the inlet manifold chamber 55, the arrays being arranged consecutively from the first end 51 to the second end 52 of the manifold chamber 55, with the number of horn-shaped portions in each array increasing progressively from the first array 30(1) to the last array 30(3). Further, the plurality of horn-shaped portions 30(1)(i,ii), 30(2)(i-vi), and 30(3)(i-xii) are arranged hierarchically such that the horn-shaped passages of a given one of the arrays are fluidly connected to two or more horn-shaped passages of a successive array that is closer to the second end 52 of the manifold chamber 55. In each hierarchical portion 30(1)(i,ii), 30(2)(i-vi), or 30(3)(i-xii) within the manifold chamber 55, adjacent horn-shaped portions in the plurality of arrays (in the column direction 500) are separated by corresponding walls located within that manifold chamber 55.

[0051] The horn-shaped portion 30(3)(i-xii) of the last stage of the hierarchical arrangement depicted in FIG. 4 is divided into twelve portions at the end of the wall proximate the second end 52. Furthermore, for acoustic reasons, it may be desirable to not have a width proximate the second end 52 of any individual horn-shaped portion at that point in the column direction 500 that exceeds one-twelfth of the overall width. In other words, the width of each horn-shaped portion in the column direction 500 is less than one-twelfth of the width of the second end 52 of the manifold chamber 55 in the column direction 500. This may improve acoustic performance by rejecting the first transverse resonance frequency. It may be appreciated that the twelve horn-shaped portions are due to the length of the actuator component 150 and the speed of sound in a typical fluid, c, for a droplet ejection head for inkjet printing. The number of desired horn-shaped portions may vary depending on the length of the actuator component 150 in the column direction 500 and the speed of sound in the ejection fluid used. Furthermore, for acoustic reasons, it may be preferred that all of the horn-shaped portions 30(3)(i-xii) are of equal length in the column direction at the end adjacent the second end 52 of the manifold chamber 55.

[0052] Referring now to FIG. 5, a manifold component 550 according to another exemplary embodiment is shown. More specifically, FIG. 5A is a cross-sectional view of the manifold component 550, FIG. 5B is an end view of the manifold component 550 shown in FIG. 5A, and FIG. 5C is a side view of the manifold component 550 shown in FIG. 5A and FIG. 5B. It can be seen from FIG. 5A that the manifold component 550 has a manifold chamber 55 similar to the embodiment shown in FIG. 3. It can also be seen from FIG. 5C that there are two additional manifold chambers 60(a, b) that overlap the manifold chamber 55 in the depth direction 510. It can be seen from FIG. 5A that the manifold chamber 60(a) is a copy of the inverted geometry of the manifold chamber 55 and has multiple horn-shaped portions 35(a) (x, y, z) arranged side by side or adjacent to each other in a column direction 500. 5A, the second manifold chamber 60(b) is identical to the first manifold chamber 60(a) and is located at an opposite depth 510 from the manifold chamber 55. Throughout the following description, similar reference numbers are used for component parts of the two manifold chambers 60(a,b) with the addition of (a) or (b) accordingly.

[0053] The embodiment depicted in Fig. 5 is an arrangement similar to that shown in Fig. 2, which allows for so-called "through-flow" of fluid when connected to a suitable fluid supply. Thus, in operation, port 120 may act as an inlet port, manifold chamber 55 may act as an inlet manifold chamber, manifold chamber 60(a,b) may act as an outlet manifold chamber, and port 220(a,b) may act as an outlet port. The main difference compared to the embodiment depicted in Fig. 2, which has one inlet manifold chamber 55 and one outlet manifold chamber 60, is that in the embodiment of Fig. 5, there is a ratio of two outlet manifold chambers 60(a,b) to one inlet chamber 55.

[0054] 5, the actuator component 150 has two rows (not shown) of fluid chambers extending parallel to one another in a row direction 500. As before, each fluid chamber in a row can be provided with at least one respective actuating element, and at least one respective nozzle, each actuating element operable to eject droplets of fluid through a corresponding at least one of the nozzles in an ejection direction 505. This exemplary arrangement thus has at least two rows of nozzles, each row corresponding to a particular row of fluid chambers.

[0055] During operation in flow-through mode, the manifold component 550 depicted in FIG. 5 may allow fluid to pass from the inlet port 120 through the inlet manifold chamber 55 to the actuator component 150, where the fluid path will split such that a portion of the fluid passes into a first row of fluid chambers through individual inlets to each fluid chamber therein, and another portion of the fluid passes through a second row of fluid chambers through individual inlets to each fluid chamber in the other row. A portion of the fluid passing into the chambers may be ejected in the form of droplets, while the remaining portion exits the chambers through the respective fluid chamber outlets. The fluid chamber outlets of the first row fluidly connect to the outlet manifold chamber 60(a) and thus to the outlet port 220(a). The fluid chamber outlets of the second row fluidly connect to the outlet manifold chamber 60(b) and thus to the outlet port 220(b). When operating the embodiment depicted in FIG. 5 in a flow-through mode, it may be preferable to balance the fluid split so that half the fluid follows one path through the manifold component 550 and half the fluid follows the other path.

[0056] In operation, a portion of the fluid passing through any individual fluid chamber may be ejected in response to a drive signal provided by wiring (not shown) to the actuation element(s). The outlet ports 220(a,b) may be connected in some manner to a single fluid outlet path or may be separately connected to individual fluid outlet paths to remove fluid from the manifold component 550. In the example shown in FIG. 5, since there is a single port 120 and a single inlet manifold chamber 55, it is clear that in operation, this arrangement provides a single fluid type to both rows of fluid chambers and therefore both rows of nozzles eject the same fluid type. This arrangement may allow for tight packing of the rows of nozzles within the actuator component 150 and may be appropriate, for example, where there are space constraints and / or where a high nozzle density is required to form a high resolution droplet ejection head. In the embodiment depicted in FIG. 5, the second end 52 of the inlet manifold chamber 55 provides a fluid connection in parallel to two rows of fluid chambers, and each of the outlet manifold chambers 60(a) and 60(b) provides a fluid connection in parallel to one row of fluid chambers.

[0057] As can be seen from FIG. 5A, similar to the embodiment depicted in FIG. 3, the manifold component 550 comprises first and second manifold sections 100, 200. The second manifold section 200 is located between the first manifold section 100 and the actuator component 150. The second manifold section 200 has three slots, one slot 20(2) fluidly connects the horn-shaped portion 30(x, y, z) to the second end 52 of the inlet manifold chamber 55 and then to the actuator component 150. Two further slots 25(2)(a) and 25(2)(b) on either side of the slot 20(2) in the depth direction 510 fluidly connect the second end 62(a, b) of the outlet manifold chamber 60(a, b) to the horn-shaped portion 35(a, b)(x, y, z).

[0058] As previously described with respect to the embodiment depicted in FIG. 3, each inlet horn-shaped portion 30(x,y,z) is positioned to cover a portion of the second end 52 in the row direction 500 such that each provides a fluid connection in parallel to a respective group of chambers in one or more rows in the actuator component 150. Similarly, the outlet horn-shaped portion 35(a,b)(x,y,z) is positioned to provide a fluid connection in parallel to a respective group of chambers in one or more rows in the actuator component 150. In operation, each outlet horn-shaped portion 35(a,b)(x,y,z) primarily receives fluid from a respective group of fluid chambers adjacent to it in the row direction 500. However, the walls 75(a,b)(i,ii) do not extend into the slots 25(2)(a,b) and therefore some fluid may mix therein.

[0059] In an alternative arrangement, fluid may be supplied to the actuator component 150 from all three ports 120 and 220(a,b) such that the droplet ejection head may be considered to be operated in a non-through flow mode.

[0060] Attention is now directed to Figures 6A-6C. Figure 6A is the inlet-only fluid path of manifold component 10 according to a first test design, Figure 6B is the fluid path of manifold component 650 according to a further embodiment, and Figure 6C is a graph comparing the calculated performance of manifold components 10 and 650. As can be seen in Figure 6B, manifold component 650 is an embodiment similar to that of Figure 3, where manifold chamber 55 is an inlet manifold chamber 55 and there are multiple horn-shaped portions 30(s-z). Such an embodiment may be described as including a multi-cell acoustic horn or may be described as a multi-cell "horn" manifold. Also, with respect to the manifold components of Figures 2 and 3, the embodiment depicted in Figure 6B includes a change in cross-sectional shape from a circular shape consistent with port 120 to an elongated shape consistent with actuator component 150 in portion 20(1).

[0061] As can be seen by comparing Figures 6A and 6B, the test design and the horned manifold component differ in that the former has multiple acoustic horns rather than a hyperbolic acoustic horn, but both the test design and the horned manifold component were designed to share certain features: The manifold chambers 55' and 55 in the test manifold component 10 and the horned manifold component 650 both have rectangular second ends 52', 52 of the manifold chambers 55', 55, with the inlet ports opening at the same location relative to the second ends 52', 52 of the manifold chambers 55', 55.

[0062] Attention is now directed to FIG. 6C, which is a graph showing the reflection coefficient of an acoustic pressure wave of the manifold component 10, 650 illustrated in FIGS. 6A and 6B as the frequency of ejection is varied. The reflection coefficient was calculated using finite element analysis to examine the response of a horned manifold according to FIG. 6B, and a test manifold according to FIG. 6A. The calculations were performed using the assumption of a rigid piston to perform a frequency sweep from 0 to 100 kHz. The rigid piston was placed at the second end 52, 52' in a position similar to that of the actuator component 150.

[0063] As can be seen in FIG. 6C, a reflection coefficient of 0 corresponds to no reflection, with all acoustic waves being transmitted from the manifold component through the cross-sectional area A2. A reflection coefficient of 1 means that there is no transmission, with all of the acoustic waves being reflected back to the cross-sectional area A1. For droplet ejection head designs utilizing one or the other of manifold components 10 (test) and 650 (horn), the frequency range considered is 0-100 kHz, with 0-100 kHz being the droplet ejection frequency (100 kHz being the upper frequency limit for the droplet ejection head of this embodiment). Preferably, the manifold components for the droplet ejection head may have the lowest possible reflection coefficient over the considered frequency range of 0-100 kHz. It can be seen from FIG. 6C that for the horned manifold component 650, the reflection coefficient is reduced over a substantial portion of the considered range compared to the test manifold component 10. It can be appreciated that for droplet ejection heads with different frequency conditions / requirements, improved manifold components may be designed for an upper frequency limit different from 100 kHz.

[0064] Considering now FIG. 7, FIG. 7A is a cutaway three-dimensional view of the fluid paths in a manifold component 110 that is flow-through enabled according to a second test design. This may be referred to as the "test" manifold component. FIG. 7B(a) is a cutaway three-dimensional view of the fluid paths in a manifold component 750 according to another embodiment that is flow-through enabled and has multiple horn-shaped portions. This may be referred to as the "horn" manifold component. FIG. 7B(b) is a cross-sectional view through the inlet manifold chamber 55 of the manifold component 750 depicted in FIG. 7B(a), also including slot 20(2). FIG. 7B(c) is a cross-sectional view through the outlet manifold chamber 60(a) of the manifold component 750 depicted in FIG. 7B(a), also including slot 25(2)(a). FIG. 7C compares the calculated reflection coefficients over a frequency range for the test manifold component according to FIG. 7A and the horned manifold component according to FIG. 7B. The calculations were performed in a similar manner as described above with respect to FIG. 6C.

[0065] 7B(a), the manifold component 750 illustrated therein is similar to the embodiment illustrated in FIG. 5 in that it has multiple horn-shaped portions and is flow-through compatible. It differs from the embodiment of FIG. 5 in that the outlet manifold chamber 60(a) is not an identical reflection of the inlet manifold chamber 55 to facilitate connection to a fluid supply. The outlet manifold chambers 60(a) and 60(b) in the manifold component 750 are nearly identical to each other. It can further be seen from FIG. 7B(a) that the outlet manifold chambers 60(a,b) connect to a single port 220 and that the transition portion 25 acts to merge the fluid exiting both outlet manifold chambers 60(a,b) before connecting to the port 220. The multiple horn-shaped portions 30(x,y,z) and 35(a,b)(x,y,z) may have a cross-sectional area that increases hyperbolically over at least a portion of the distance in the discharge direction 505.

[0066] The exemplary embodiment shown in Figure 7B(a) generally relates to a manifold component 750 for a droplet ejection head. The manifold component 750 comprises a mounting 80 for receiving an actuator component 150 providing one or more rows of fluid chambers, each chamber comprising at least one respective actuating element and at least one respective nozzle, the at least one actuating element for each chamber operable to eject droplets of fluid in an ejection direction 505 through the corresponding at least one nozzle, each row extending in a row direction 500. The manifold component 750 has manifold chambers 55, 60(a), 60(b) extending from respective first ends 51, 61(a), 61(b) to respective second ends 52, 62(a), 62(b) and widening from said first ends 51, 61(a), 61(b) to said second ends 52, 62(a), 62(b). The second ends 52, 62(a), 62(b) of the manifold chambers 55, 60(a), 60(b) provide parallel fluid connection to at least a group of the chambers in the one or more rows and are located adjacent to the mounting portion 80. There are ports 120, 220, the former of which open into the manifold chamber 55 at the first end 51 and the latter of which open into the manifold chambers 60(a), 60(b) at the first ends 61(a), 61(b). The manifold chambers 55, 60(a), 60(b) comprise a plurality of horn-shaped passages 30(x, y, z), 35(a, b)(x, y, z), the cross-sectional area of ​​each of which decreases at a decreasing rate with distance from the second ends 52, 62(a), 62(b) of the manifold chambers 55, 60(a), 60(b). The horn-shaped passages in each respective manifold chamber 55, 60(a), 60(b) are arranged side-by-side in an array extending generally in the column direction 500. The ports 120, 220 are in parallel fluid connection with their respective horn-shaped passages 30(x, y, z) and 35(a, b)(x, y, z).

[0067] As can be seen from FIG. 7B(b), the horn-shaped passage 30(x,y,z) comprises a first side (701-703)(i) and a second side (701-703)(ii) spaced apart in the column direction 500, the sides 701-703(i,ii) being substantially concave. With respect to the manifold component 250 of FIG. 2, the manifold chamber 55 depicted in FIG. 7B(a) and FIG. 7B(b) includes a change in cross-sectional shape in the portion 20(1) in this implementation from a circular shape that aligns with the port 120 to an elongated shape (rectangular in this example) that aligns with the actuator component 150 (not shown). The port 120 is also offset from the manifold chamber 55 in the depth direction 510, so the portion 20(1) also includes a depth-wise moulding connecting the two.

[0068] Similarly, as can be seen from FIG. 7B(c), the horn-shaped passage 35(a)(x,y,z) includes a first side (711-713)(i) and a second side (711-713)(ii) spaced apart in the column direction 500, the sides 711-713(i,ii) being substantially concave. Although not shown, it can be understood that the manifold chamber 60(b) is similarly configured. One or more of the horn-shaped passages 30(x,y,z), 35(a,b)(x,y,z) may have a hyperbolic profile. In some embodiments, all of the horn-shaped passages 30(x,y,z), 35(a,b)(x,y,z) may be shaped as hyperbolic acoustic horns, whereby such horn-shaped passages 30(x,y,z), 35(a,b)(x,y,z) may be described as hyperbolic horn-shaped portions 30(x,y,z) 35(a,b)(x,y,z).

[0069] Manifold chambers 60(a), 60(b) depicted in FIG. 7B(a) (and 60(a) depicted in FIG. 7B(c)) also include a change in cross-sectional shape of transition portion 25 from an elongated shape that aligns with actuator component 150 (not shown) to a circular shape that aligns with port 220. Also, as previously mentioned, outlet manifold chambers 60(a,b) connect to a single port 220, and transition portion 25 acts to combine fluid exiting both outlet manifold chambers 60(a,b) before connecting to port 220.

[0070] 7B(d) is a detailed view of the fluid pathway depicted in FIG. 7B(a), depicting in greater detail portions 20 and 25. It can be seen that inlet port 120 is offset from portion 20 such that portion 20 further includes a blending change in position in the depth direction 510 that connects inlet port 120 to rectangular cross-sectional area 4.

[0071] With further consideration of FIG. 7B(d), it can be seen that the transition portion 25 comprises two arms 25(a) and 25(b), one for each outlet manifold chamber 60(a)(b), which merge from rectangular cross-sectional areas 1(a) and 1(b) to elliptical cross-sectional areas 2(a) and 2(b), and then join to form a single passageway 25(c) that connects to the outlet port 220 via a circular cross-sectional area 3. The transition portion 25 has a fused cowl-like shape, which may improve fluid flow therein and may also help reduce acoustic crosstalk by aiding in the transmission of acoustic waves from the manifold chambers 60(a) and 60(b) to the fluid supply. It can be understood that this is just one implementation and that other combinations of cross-sectional shapes and areas with fused regions can be combined in any suitable manner to provide the transition portion 25 with a fused cowl-like form, for example, by sweeping a range of cross-sectional shapes(s) and / or cross-sectional areas along a suitable path or trajectory. In some implementations, the manifold chambers may have an elongated cross-sectional area. The transition portion 25 may connect several cross-sectional areas along the length of the transition portion 25 at both ends that are connectable to ports and manifold chambers. In some implementations, the cross-sectional shape of the fused cowl-like form of the transition portion 25 is selected from a list including elongated, rectangular, oval, and circular. In some implementations, such fused cowl-like form may be formed from 3D printing. Such a transition portion 25 may be suitably used in implementations having at least two or more manifold chambers, at least two of which are connected to a single port that may be the outlet port 220, and the transition portion 25 connects the port 220 to at least two manifold chambers 60(a)(b). In such implementations, the transition portion 25 comprises at least one passageway 25(c) and further comprises an arm 25(a)(b) for each manifold chamber 60(a)(b). Further manifold chambers can be connected using a suitable number of additional arms (one for each manifold chamber), and the arms can be joined together using any suitable number of connecting passages.It may be appreciated that such a transition portion 25 may be used for two or more inlet manifold chambers or two or more outlet manifold chambers to connect to the inlet or outlet ports, respectively. Moreover, such a transition portion 25 may be suitably used in implementations in which two or more manifold chambers include one or more horn-shaped passages, or in other implementations in which two or more manifold chambers do not include a horn-shaped passage.

[0072] FIG. 7C compares the reflection coefficients calculated over the frequency range of 0-100 kHz for the test manifold component according to FIG. 7A and the horned manifold component according to FIG. 7B. FIG. 7C(a) compares the reflection coefficients calculated over the frequency range of the inlet manifold chamber for the test manifold (FIG. 7A) and the horned manifold (FIG. 7B). FIG. 7C(b) compares the reflection coefficients calculated over the frequency range of the outlet manifold chamber for the test manifold (FIG. 7A) and the horned manifold (FIG. 7B). It can be seen that the reflection coefficient of the horned manifold is greatly reduced in both the inlet and outlet chambers compared to the test manifold.

[0073] Considering now FIG. 8, there are shown respective print samples produced using a droplet ejection head with a test manifold component similar to that of FIG. 7A and a droplet ejection head with a horned manifold component similar to that of FIG. 7B. The print direction is along the vertical direction. The head was operated in flow-through mode with a droplet frequency of 110 kHz. The samples were printed using magenta ink. It can be seen that the grey scale increased continuously from the top to the bottom of the sample with each print block. It can be clearly seen that the horned manifold component (FIG. 8(a)) provided an improvement in terms of the quality of the printed test samples compared to the test manifold component (FIG. 8(b)). It is believed that the defects in the print samples of the test manifold component are due to acoustic crosstalk.

[0074] FIG. 9(AC) is a graph comparing drop velocity data generated using a printhead with a test manifold component according to FIG. 7A with a printhead with a horned manifold component according to FIG. 7B. The data was collected using a commonly available brand of droplet measurement and analysis tool (JetXpert™ Dropwatcher from ImageXpert®). The results compare drop velocity data for droplets ejected from one row of 360 nozzles in the actuator component 150 at droplet ejection frequencies (and drive signals provided to the actuators in the fluid chambers) of 5 kHz (FIG. 9A), 20 kHz (FIG. 9B), and 40 kHz (FIG. 9C). It can be clearly seen that at the measured frequencies, the drop velocity is more consistent in the row direction 500 for the horned manifold as opposed to the test manifold. At higher frequencies, significant waviness and variability in the drop velocity profile in the row direction 500 can be seen for the test manifold as compared to the horned manifold.

[0075] 10 is a schematic diagram depicting a method of designing a horn-shaped portion for a manifold component according to one embodiment described herein. As shown in FIG. 10, the method involves determining an initial shape of a manifold chamber 55 according to which the manifold chamber extends from a first end 51 to a second end 52 along an initial linear path 515, and there exists a series of cross sections A(x) perpendicular to the initial path 515, the area of ​​said cross sections increasing with increasing distance from the first end 51, from A2 to A1, such that there exists at least a portion of the manifold chamber in which the area of ​​cross sections A(x) increases hyperbolically between the first end 51 and the second end 52. The next step involves deforming the initial path 515 to generate a modified path 515' by moving each cross section A(x) to a corresponding point on the initial path 515, thereby providing a modified shaped manifold chamber 55' having cross sections A2', A(x)' with the same cross-sectional area as cross sections A2 and A(x). It can be seen that cross section A1 of the second end 52 remains in its original position. It should be understood that while the deforming step depicted in FIG. 10 is such that cross sections A2', A(x)' and A1 remain substantially parallel, this may not be necessary in all embodiments. Furthermore, the modified path 515' may be a straight path and the deforming step may be such that cross sections A2', A(x)' and A1 are substantially parallel to each other and angled relative to the modified path 515'. It will be appreciated that in other embodiments, other transforming steps may be performed, for example using non-linear variations of the path 515' or other forms of translation or rotation of portions of the initial path 515.

[0076] It should generally be appreciated that for reasons of space constraints, it may be desirable to have a manifold component according to any of the embodiments described herein in which the extent of each manifold chamber 55, 60 in the discharge direction 505 is no more than twice its extent in the row direction 500, and in some embodiments, the extent of each manifold chamber in the row direction 500 is no more than twice its extent in the discharge direction 505. In some embodiments, it may be preferred that the extent of each manifold chamber in the row direction 500 is approximately equal to its extent in the discharge direction 505, similar to that shown in Figures 3 and 4. It may be appreciated that where space constraints exist, a multi-cell horn having multiple horn-shaped portions may be used to advantageously enable a compact design, as depicted in Figures 3 and 4, and elsewhere.

[0077] It may be appreciated that in some embodiments, the mounting portion 80 may comprise a flat receiving surface as in FIG. 1A to which the actuator component 150 may be attached, for example, by adhesive. Alternatively, the mounting portion 80 may have a more complex arrangement of mounting surfaces and connecting elements, as well as fastening devices such as screws or pins, or push or slide fits, or the use of adhesives, to allow for secure attachment of the actuator component 150 to any of the manifold components described herein. It should be appreciated that although the fluid chambers have been described as being in rows of fluid chambers, the rows are not necessarily straight and the fluid chambers may be staggered within the rows.

[0078] In some embodiments, the first portion 20 may comprise a hyperbolic acoustic horn and may include a change in cross-sectional shape blending from the cross-sectional area of ​​the port 120 to a cross-sectional area that accommodates the actuator component 150. It may therefore be appreciated that the offset 58 may not be a required feature in such embodiments. It should further be appreciated that the offset 58 is not necessarily a linear distance in the discharge direction 500, but rather depends on the shape of the manifold chamber 55, the route taken by the central passage 515, and where the portion that forms the hyperbolic acoustic horn occurs. It may therefore be appreciated that the shape of the first portion 20 may depend on the cross-sectional shape(s) of the port and actuator component.

[0079] It may further be understood that the manifold component may comprise multiple manifold chambers as described herein and arranged in any manner suitable for the application. The manifold component may comprise multiple inlet manifolds and / or multiple outlet manifolds. Some or all of the features described herein may be combined in any suitable manner to form a manifold component.

[0080] It may be further appreciated that where there are two or more of the same type of manifold components (depicted in Figures 5A and 7B), they may all have their own individual ports (depicted in Figure 5A) or may share a common port (depicted in Figure 7B). In the latter case, as depicted in Figure 7B, transition section 25 may split the fluid path into a suitable number of arms to connect to the respective manifold chambers, and blend the cross-sectional shape and / or area of ​​the fluid path from that of the common port to one that accommodates actuator component 150. It should be appreciated that such an arrangement will work regardless of whether the manifold chamber acts as an inlet or outlet manifold.

[0081] It should be appreciated that the manifold components described herein are suitable for inclusion in a wide variety of droplet ejection heads, and in particular, the manifold components described herein are suitable for inclusion in droplet ejection heads having a variety of applications.

[0082] In this regard, it should be appreciated that a variety of fluids can be ejected by the droplet ejection head, depending on the particular application.

[0083] For example, a particular head can be configured to eject ink onto, for example, a sheet of paper or card, or other receiving medium such as a ceramic tile or a molded article (e.g., a can, a bottle, etc.) Droplets of ink can be deposited to form an image, such as in inkjet printing applications (wherein the droplet ejection head may be referred to as an inkjet printhead, or in specific examples, a drop-on-demand inkjet printhead).

[0084] Alternatively, the droplet ejection head can eject droplets of fluid that can be used to build structures, for example, an electrically active fluid can be deposited onto a receiving medium such as a circuit board to enable prototyping or manufacturing of an electrical device. In an embodiment, a polymer-containing fluid or molten polymer can be deposited in successive layers to generate a 3D object (as in 3D printing). In yet other applications, the droplet ejection head can be adapted to deposit droplets of a solution containing biological or chemical substances onto a receiving medium such as a microassay. A droplet ejection head suitable for such alternative fluids can be generally similar in structure to an inkjet printhead, with some adaptations made to handle the particular fluid in question, as can the manifold components therein.

[0085] It should further be noted that a droplet ejection head may be positioned to eject droplets onto a suitable receiving medium and may thus be referred to as a droplet deposition head.

[0086] For example, as discussed above, the receptor medium may be paper or card, a ceramic tile, a molded article (eg, a can, a bottle, etc.), a circuit board, or a microassay.

[0087] Nonetheless, it is by no means necessary that the droplet ejection heads described herein be configured as droplet deposition heads and eject droplets onto a receiver medium. In some applications, where the ejected droplets land may be relatively unimportant. For example, in specific embodiments, a droplet ejection head may be utilized to generate a mist of ejected droplets. Moreover, similar head structures may be used, in some cases, regardless of whether the ejected droplets land on a receiver medium. Accordingly, the more general term "droplet ejection head" has been used (where appropriate) in the disclosure above.

[0088] Manifold components as disclosed above may be suitable for drop-on-demand inkjet printheads in which the pattern of ejected droplets depends on input data provided to the head.

[0089] The droplet ejection head may include portions for the manifold components described herein for connecting the main portion of the manifold components to the ports and actuator components 150 secured to the mounting portion 80 .

[0090] The droplet ejection head may include a manifold component as described in any of the above embodiments and an actuator component 150 secured to a mounting portion 80 .

[0091] The droplet ejection head may comprise a manifold component as described in any of the above embodiments and an actuator component 150 secured to a mounting portion 80, with each group of chambers comprising at least 100 chambers.

Claims

1. A manifold component (50) for a droplet ejection head, said manifold component (50) comprising: a mounting (80) for receiving an actuator component (150) providing one or more rows of fluid chambers, each fluid chamber comprising at least one respective actuating element and at least one respective nozzle, said at least one actuating element for each fluid chamber operable to eject droplets of fluid in an ejection direction (505) through said corresponding at least one nozzle, each row extending in a row direction (500); a manifold chamber (55) extending from a first end (51) to a second end (52) and widening from said first end (51) to said second end (52), said second end (52) providing a fluid connection in parallel to at least a group of fluid chambers in said one or more rows and located adjacent said mounting portion (80); and at least one port (120), each port (120) opening into said manifold chamber (55) at its first end (51); The manifold chamber (55) has a hyperbolic horn-shaped portion between the first end (51) and the second end (52), the hyperbolic horn-shaped portion being formed as a hyperbolic acoustic horn, the hyperbolic acoustic horn belonging to a family of hyperbolic acoustic horns with an area expansion of the wavefront, the cross-sectional area of ​​the hyperbolic horn-shaped portion being given by the following formula: A(x)=A2[cosh(mx)+Tsinh(mx)]^2; where T is a parameter that sets the shape of the hyperbolic acoustic horn; A2 is the cross-sectional area at the first end (51) proximate the port (120); A(x) denotes the cross-sectional area at a given location x along a central path (515) through the center of the hyperbolic horn portion, the central path extending from the center of the first end to the center of the second end; m is defined as m=(2πf_c) / c, c represents the speed of sound in the fluid, f_c represents the cutoff frequency, The cutoff frequency is the frequency below which most of the energy is reflected and above which most of the energy is transmitted. Manifold components.

2. 2. The manifold component (50) of claim 1, wherein each hyperbolic horn-shaped portion extends over at least a majority of the distance between the first end (51) and the second end (52) of the corresponding manifold chamber (55).

3. 3. The manifold component (50) of claim 2, wherein each hyperbolic horn-shaped portion extends 0.6 to 0.9 times the distance between the first end (51) and the second end (52) of the corresponding manifold chamber (55).

4. For each hyperbolic horn section, a corresponding central path (515) is defined, said corresponding central path (515) extending centrally through said hyperbolic horn-shaped portion from the center of its first end to the center of its second end, and at each point on said central path (515), a corresponding width (57) is defined, said corresponding width (57) being measured at said point in a direction perpendicular to said central path (515) and perpendicular to a depth direction (510), said depth direction being perpendicular to said row direction (500) and said discharge direction (505); 4. The manifold component (50) of claim 1, wherein for the hyperbolic horn-shaped portion, the width (57) varies generally according to a hyperbolic function of distance from the first end of the hyperbolic horn-shaped portion along the central path (515).

5. 5. The manifold component (50) of claim 1, wherein each hyperbolic horn-shaped portion has a generally constant depth in a depth direction (510), said depth direction (510) being perpendicular to said row direction (500) and said discharge direction (505).

6. To said manifold chamber (55), 6. A manifold component (50) as claimed in any one of claims 1 to 5, wherein a corresponding central passage (515) is defined, said corresponding central passage extending centrally through said manifold chamber (55) in question from a centre of said first end (51) to a centre of said second end (52) thereof, said central passage (515) extending generally parallel to said discharge direction (505) at said second end (52) of said manifold chamber (55) in question.

7. 7. A manifold component (50) as claimed in any one of claims 1 to 6, wherein the second end (52) of the manifold chamber (55) is defined by an opening of elongated shape parallel to the row direction (500), the opening having a major axis extending in the row direction (500) and a minor axis extending in the depth direction (510), the opening of the manifold chamber (55) at the second end (52) having points at both ends of its major axis that define the same angle (53) between the plane of the opening and a wall of the manifold chamber (55).

8. 8. The manifold component (50) of claim 1, further comprising a transition portion (25), the transition portion (25) including a change in cross-sectional shape blending from a cross-sectional area of ​​the port (120) to a cross-sectional area that accommodates the actuator component.

9. The manifold component (50) of claim 8, wherein the transition portion (25) further comprises a hyperbolic acoustic horn.

10. 10. The manifold component (50) of claim 1, wherein the manifold component (50) comprises two or more manifold chambers (55), at least two of the two or more manifold chambers (55) being connected to one port (120).

11. The manifold component (50) of claim 10 when relying on claim 8 or 9, wherein the transition portion (25) connects the port (120) to the at least two manifold chambers (55), the transition portion (25) comprising at least one passage (25(c)) and further comprising an arm (25(a), 25(b)) for each manifold chamber (55) of the at least two manifold chambers (55).

12. 12. The manifold component (50) of any one of claims 1 to 11, wherein the manifold chamber (55) comprises a plurality of the hyperbolic horn shaped portions (30(x,y,z), 30(1)(i-ii), 30(2)(i-vi), 30(3)(i-xii)) arranged side by side in an array.

13. 13. The manifold component (50) of claim 12, wherein the manifold chamber comprises an array of a plurality of the side-by-side hyperbolic horn-shaped portions, the array including a first array of hyperbolic horn-shaped portions (30(1)(i-ii)) proximate the first end (51) of the manifold chamber and a last array of hyperbolic horn-shaped portions (30(3)(i-xii)) proximate the second end (52) of the manifold chamber, the arrays being arranged consecutively from the first end (51) to the second end (52) of the manifold chamber, the number of hyperbolic horn-shaped portions in each array increasing progressively from the first array (30(1)(i-ii)) to the last array (30(3)(i-xii)).

14. 14. The manifold component (50) of claim 13, wherein the plurality of hyperbolic horn-shaped portions are arranged hierarchically such that a hyperbolic horn-shaped portion of a given one of the arrays is fluidly connected to two or more hyperbolic horn-shaped portions of a successive array that are closer to the second end (52) of the manifold chamber.

15. A droplet ejection head comprising a manifold component (50) according to any one of claims 1 to 14, and the actuator component secured to the mounting portion (80).

16. 1. A method for designing a manifold component (50) for a droplet ejection head, the manifold component (50) comprising: a mounting (80) for receiving an actuator component providing one or more rows of fluid chambers, each fluid chamber comprising at least one respective actuating element and at least one respective nozzle, said at least one actuating element for each fluid chamber operable to eject droplets of fluid in an ejection direction (505) through said corresponding at least one nozzle, each row extending in a row direction (500); a manifold chamber (55) extending from a first end (51) to a second end (52), said second end (52) providing a fluid connection in parallel to at least a group of fluid chambers in said one or more rows and located adjacent said mounting portion (80); at least one port (120), each port (120) opening at its first end into the manifold chamber (55), the manifold chamber (55) having a hyperbolic horn-shaped portion between the first end (51) and the second end (52), the hyperbolic horn-shaped portion being formed as a hyperbolic acoustic horn, the hyperbolic acoustic horn belonging to a family of hyperbolic acoustic horns with an area expansion of the wavefront, the cross-sectional area of ​​the hyperbolic horn-shaped portion being given by the formula: A(x)=A2[cosh(mx)+Tsinh(mx)]^2; where T is a parameter that sets the shape of the hyperbolic acoustic horn; A2 is the cross-sectional area at the first end (51) proximate the port (120); A(x) denotes the cross-sectional area at a given location x along a central path (515) through the center of the hyperbolic horn portion, the central path extending from the center of the first end to the center of the second end; m is defined as m=(2πf_c) / c, c represents the speed of sound in the fluid, f_c represents the cutoff frequency, the cutoff frequency being the frequency below which most of the energy is reflected and above which most of the energy is transmitted; The method further comprising: determining an initial shape of the manifold chamber (55) according to which the manifold chamber (55) extends from a first end (51) to a second end (52) along an initial linear path (515) and there exists a series of cross sections (A(x)) perpendicular to the initial path (515), the cross-sectional area of ​​the cross sections (A(x)) increasing with increasing distance from the first end (51), such that there exists at least a portion of the manifold chamber (55) in which the cross-sectional area of ​​the cross sections (A(x)) increases hyperbolically; deforming the initial path (515) to generate a modified path (515') with at least a portion of the manifold chamber (55) between the first end (51) and the second end (52) in which the measured cross-sectional area perpendicular to the initial linear path (515) increases, resulting in a hyperbolic increase in cross-sectional area, wherein each cross-section (A(x)) is moved at a corresponding point on the initial path (515), thereby providing a modified shape of the manifold chamber (55').

17. 17. The method for designing a manifold component (50) of claim 16, wherein said deforming step is such that said cross sections (A(x)) are substantially parallel to one another.

18. The method for designing a manifold component (50) according to claim 16 or 17, wherein the modified path (515') is a straight path.

Images