Patent Description:
A fluid ejection device with tapered ports according to the preamble of claim <NUM> is known from <CIT> and from <CIT>. <CIT> discloses a fluid ejection device with a straight port having a width of <NUM> connected to ejection chambers formed in a barrier layer, wherein the barrier layer has a thickness of <NUM>.

The present invention refers to a fluid ejection device according to claim <NUM> and to a method according to claim <NUM>. Preferred embodiments of the invention are defined in the appended dependent claims.

Disclosed herein are example fluid ejection devices and methods that utilize fluid feed holes to supply fluid from a single fluid supply passage to ejection chambers. In contrast to fluid ejection devices which supply fluid to ejection chambers from a continuous elongate slot extending between columns of such ejection chambers and respective nozzles, the example fluid ejection devices and methods employing multiple individual fluid feed holes in place of the slot may provide enhanced mechanical robustness, may facilitate more compact and less expensive electrical connections, and may achieve more effective heat transfer. In particular, the additional structure extending between consecutive fluid feed holes may offer enhanced mechanical support for layers of materials forming the nozzles and ejection chambers, may provide surfaces for electrical trace routings from one column to another and may provide a greater surface area for the transfer of heat to the fluid being ejected to dissipate heat from the device. In many implementations, the fluid feed holes, being smaller than the slots, also facilitate higher velocity fluid flow, increasing heat transfer coefficients to further enhance the dissipation of heat from the fluid ejection device.

During use of such fluid ejection devices, bubbles may form within or near the ejection chambers. For example, in implementations where the fluid is heated to vaporize small portions of the fluid and create bubbles that expel fluid through a nozzle, the fluid ejection device may also heat up. This may result in the fluid flowing within the fluid ejection device being warmed to a temperature such that dissolved air within the fluid is released in the form of bubbles. These bubbles may block or occlude the flow of fluid to the fluid ejection chambers. Although the formation of bubbles may in some implementations be reduced by cooling the fluid or the fluid ejection device, such a solution may result in large temperature ranges or discrepancies across the fluid ejection device which may detrimentally impact ejection consistency and performance.

Rather than reducing the initial formation of bubbles, the fluid ejection devices according to the invention facilitate the discharge of any bubbles that are created. The ports of the fluid feed holes of the example fluid ejection devices are specifically sized to pass such bubbles out of the ejection chambers. As a result, bubbles formed by the fluid actuators are less likely to block or impede the flow of ink from the fluid feed holes to the ejection chambers. In one implementation, the fluid ejection chambers have a height, wherein the minimum dimension of the port of each fluid feed hole is sized based upon this height so as to pass bubbles out of the ejection chambers or out of passages leading to the ejection chambers.

According to the invention, the minimum dimension of the port of each fluid feed hole is at least <NUM> times the height of the fluid ejection chamber. In high flow systems, systems having a Reynolds value of greater than <NUM> proximate the fluid ejection chamber, such fluid feed holes permit bubbles to be discharged through the fluid feed holes rather than being trapped between the fluid feed holes and the ejection chamber. In one implementation, the minimum dimension of the port of each fluid feed hole is at least twice the height of the fluid ejection chamber. In low flow systems, systems having a Reynolds value of less than one proximate the fluid feed chamber, such fluid feed holes permit bubbles to be discharged through the fluid feed holes rather than being trapped between the fluid feed holes in the ejection chamber.

In some of the embodiments of the invention, a fluid ejection die is provided in a molding or molded structure. The molding or molded structure includes an elongate channel or fluid supply passage for supplying fluid to the fluid feed holes. The die is embedded in the mold. The fluid supply passage is part of the molded structure and the fluid feed holes are part of the die. In one implementation, the molded structure at least partially encapsulates a single die or a plurality of parallel dies or a plurality of staggered dies. In one implementation, the molded structure comprises at least one fluid passage per die.

In some embodiments, the die is provided in a cut out window of a PCB that is also embedded in the mold. A row of fluid feed holes extends parallel to a length axis of the elongate molding channel. Ribs between the fluid feed holes extend across the mold channel. Two rows of drop generators extend along the fluid feed hole downstream openings, for example one row at each side of the fluid feed hole openings, so that the ribs extend between the two rows of drop generators. Pillars may be provided on top of the ribs, between the drop generator rows. Pillars may also be provided near chamber inlets. A single, common manifold may be provided that fluidically connects to each of the chambers and fluid feed holes. In some example a pitch of the fluid feed holes is the same as a pitch of the drop generators in one row of drop generators.

In some embodiments, one mold channel is to provide fluid to one fluid feed hole array (e.g. row). In another example, one mold channel may provide fluid to a plurality of feed hole arrays (e.g. rows) either in a single die or in multiple corresponding dies. In some embodiments, the dies may be of relatively small width, for example having a ratio of length to width of <NUM> or more, and in some implementations, <NUM> or more, <NUM> or more or <NUM> or more. Such dies may be called "slivers". The dies may also be relatively thin, for example generally consisting of a bulk silicon substrate and a thin film fluidics layer.

In the illustrated examples, the multiple fluid ejection devices and PCB that are mounted to a molding. Herein, mounting includes both attached to and embedded. In some embodiments, the fluid ejection devices are embedded, for example overmolded, in the molding, while the PCBs are attached to the molded fluid ejection device after said embedding. The PCBs include a window that exposes the dies. In another example both the fluid ejection device and PCB are embedded in the molding.

The fluid ejection device of the invention includes fluid actuators, ejection chambers adjacent the fluid actuators, nozzles extending from the ejection chambers, and tapered fluid feed holes to supply fluid from a single fluid supply passage to the ejection chambers. The fluid feed holes have ports directly connected to the ejection chambers. The ports are sized to pass bubbles formed by the fluid actuators out of the ejection chambers.

In some embodiments, the fluid ejection device may include a substrate, a fluidic layer disposed on the substrate, and drop generators formed in the fluidic layer and fluid feed holes. The drop generators may comprise respective ejection chambers, respective nozzles extending from the respective ejection chambers and respective fluid actuators. Each of the ejection chambers may have a height. The fluid feed holes extend through the substrate from a single fluid supply passage. Each of the fluid feed holes may have a port connected to at least one of the ejection chambers. The port has a minimum dimension of at least <NUM> times the height. In some implementations, the port may have a minimum dimension of at least twice the height, depending upon the anticipated fluid flow rates proximate the ejection chambers.

The fluid ejection method according to the invention includes distributing portions of a volume of fluid amongst tapered fluid feed holes extending through a substrate and directing the portions through the fluid feed holes to a fluidic layer. Each of the portions may be directed from the fluid feed holes to report to at least one drop generator in the fluidic layer. The lease one drop generator may conclude and ejection chamber, a fluid actuator proximate the ejection chamber and a nozzle. The ejection chamber has a height no greater than two thirds a minimum dimension of the port.

<FIG> schematically illustrates portions of a fluid ejection device <NUM> according to an example not corresponding to the invention as defined in the claims but useful for the understanding thereof. Fluid ejection device <NUM> is to selectively or controllably eject droplets fluid. Fluid ejection device <NUM> may be employed as part of an additive or 3D printing system, may be employed as part of a two dimensional printing system in which fluid is deposited upon the two-dimensional medium, such as a sheet or web, or may be employed as part of a fluid diagnostic system, such as a system where biological, chemical or other fluid samples are identified or otherwise analyzed. Fluid ejection device <NUM> has an architecture or geometry that facilitates the discharge or conveyance of bubbles out of fluid ejection chambers. As a result, the existence of such bubbles is likely to interfere with the ejection of fluid from the device. Fluid ejection device <NUM> comprises fluid ejection chambers <NUM>, nozzles <NUM>, ejection elements in the form of fluid actuators <NUM> and feed holes <NUM>.

Fluid ejection chambers <NUM>, nozzles <NUM> and fluid actuators <NUM> cooperate to form drop generators. Each of fluid ejection chamber <NUM> comprises a volume adjacent to and between a corresponding nozzle <NUM> and a corresponding fluid actuator <NUM>. In one implementation, ejection chambers <NUM> are isolated or disconnected from one another in that fluid supplied to one of chambers <NUM> is prevented from directly flowing to the other of chambers <NUM> without flowing through the source of the fluid, the single fluid supply <NUM> (shown in broken lines) that supplies and distributes a single type or characteristic fluid to both of chambers <NUM>. In other implementations, chambers <NUM> may be connected to one another independent of fluid supply <NUM>. For example, at least one fluid passage may extend directly from one chamber <NUM> to another chamber <NUM>.

Nozzles <NUM> comprise openings extending from ejection chambers <NUM> through which fluid is ejected. Nozzles <NUM> may at least partially determine the size of the droplets being generated. In one implementation, nozzles <NUM> may be tapered. In other implementations, nozzles <NUM> may comprise un-tapered openings extending from ejection chamber <NUM>. In one implementation, each of ejection chambers <NUM> has a single associated nozzle <NUM>. In some implementations, each of ejection chambers <NUM> may be associated with multiple nozzles <NUM>.

Fluid actuators <NUM> comprise mechanisms that displace fluid within their respective ejection chambers <NUM> to expel fluid through the respective nozzles <NUM>. In one implementation, fluid actuators <NUM> are located directly opposite to the respective nozzles <NUM>. In other implementations, fluid actuator <NUM> may be slightly offset from the respective nozzles <NUM>.

In one implementation, fluid actuators <NUM> may comprise piezo-membrane based actuators, electrostatic membrane actuators, mechanical/impact driven membrane actuators, magnetostrictive drive actuators, electrochemical actuators, other such microdevices, or any combination thereof. In some implementations, the fluid actuators may displace fluid through movement of a membrane (such as a piezo-electric membrane) that generates compressive and tensile fluid displacements to thereby cause inertial fluid flow.

In some examples, each of fluid actuators <NUM> may comprise a thermal actuator having a heating element (e.g., a thermal resistor) that may be heated to cause a bubble to form in a fluid proximate the heating element. In such examples, a surface of a heating element (having a surface area) may be proximate to a surface of a fluid channel in which the heating element is disposed such that fluid in the fluid channel may thermally interact with the heating element. In some examples, the heating element may comprise a thermal resistor with at least one passivation layer disposed on a heating surface such that fluid to be heated may contact a topmost surface of the at least one passivation layer. Formation and subsequent collapse of such bubble may generate flow of the fluid.

As will be appreciated, each fluid actuator <NUM> may be connected to a controller, and electrical actuation of the fluid actuator by the controller may thereby control pumping of fluid. Actuation of the fluid actuator may be of relatively short duration. In some examples, the fluid actuator may be pulsed at a particular frequency for a particular duration. In some examples, actuation of the fluid actuator may be <NUM> microsecond (µs) or less. In some examples, actuation of the fluid actuator may be within a range of approximately <NUM> microsecond (µs) to approximately <NUM> milliseconds (ms). In some examples described herein, actuation of the fluid actuator comprises electrical actuation. In such examples, a controller may be electrically connected to a fluid actuator such that an electrical signal may be transmitted by the controller to the fluid actuator to thereby actuate the fluid actuator. Each fluid actuator of an example microfluidic device may be actuated according to actuation characteristics. Examples of actuation characteristics include, for example, frequency of actuation, duration of actuation, number of pulses per actuation, intensity or amplitude of actuation, phase offset of actuation.

In those implementations in which each of fluid actuators <NUM> comprise a thermal resistive fluid actuator, heat may be conducted not only to un-expelled fluid proximate the fluid actuator, but also to the physical material of fluid ejection device <NUM>, such as silicon. This may result in fluid ejection device <NUM> itself heating up. Such heat may be conducted to the fluid within fluid ejection device <NUM> which may result in otherwise dissolved air within the fluid being released in the form of additional bubbles. In some implementations, the fluid ejection device and contained fluid may be warmed by other heat generating electronic components, other than the fluid actuators <NUM>, to a temperature such that dissolved air within the fluid is released in the form of bubbles.

Fluid feed holes <NUM> comprise fluid passages that direct the flow of fluid to fluid ejection chambers <NUM>. Fluid feed holes <NUM> receive fluid from a single fluid supply passage <NUM> (schematically illustrated). In other words, each of fluid feed holes <NUM> has an inlet <NUM> that receives fluid from the same fluid supply <NUM>. In some implementations, fluid ejection device <NUM> may comprise multiple sets of fluid feed holes with each set of fluid feed holes (more than one fluid feed hole in each set) receiving fluid from or sharing a single fluid supply <NUM>. In some implementations, each fluid supply <NUM>, which supplies fluid to a respective set of fluid feed holes, may supply different fluids having different characteristics, such as different colors or other different properties.

As further shown by <FIG>, each of fluid feed holes <NUM> generally extends in a direction parallel to the direction in which fluid is ejected through nozzles <NUM>. Those consecutive fluid feed holes <NUM> that share a same fluid supply <NUM> are spaced by an intervening structure <NUM>. In some implementations, each ejection chamber <NUM> may be supplied with fluid by several fluid feed holes <NUM>. In yet other implementations, a fluid feed hole <NUM> may supply fluid to more than one ejection chamber <NUM>.

Each of fluid feed holes <NUM> has an outlet port <NUM> directly or indirectly connected to at least one ejection chamber <NUM>. Each outlet port is sized to pass bubbles out of or from the ejection chambers <NUM>. In the example illustrated, each outlet port is sized based upon a height H of the ejection chamber most proximate to the outlet port <NUM>. For example, in implementations where fluid ejection device <NUM> provides relatively high flow rates within fluid ejection chamber <NUM>, flow rates having a Reynolds number of greater than <NUM>, each outlet port <NUM> has a minimum dimension MD of at least <NUM> times the height. In implementations where fluid ejection device <NUM> provides slower flow rates within fluid ejection chamber <NUM>, flow rates having a Reynolds number of less than or equal to one, each outlet port <NUM> has a minimum dimension MD of at least two times the height H. The larger minimum dimension MD of outlet port <NUM> further facilitates the expulsion of bubbles in such low-flow fluid ejection devices where fluid pressure offers less assistance for expelling such bubbles throughout outlet port <NUM>.

<FIG> schematically illustrates portions of a fluid ejection device <NUM> according to the invention. Similar to fluid ejection device <NUM>, fluid ejection device <NUM> is to selectively or controllably eject droplets fluid. Fluid ejection device <NUM> may be employed as part of an additive or 3D printing system, may be employed as part of a two dimensional printing system in which fluid is deposited upon the two-dimensional medium, such as a sheet or web, or may be employed as part of a fluid diagnostic system, such as a system where biological, chemical or other fluid samples are identified or otherwise analyzed. Fluid ejection device <NUM> has an architecture or geometry that facilitates the discharge or conveyance of bubbles out of fluid ejection chambers. As a result, the existence of such bubbles is likely to interfere with the ejection of fluid from the device. Fluid ejection device <NUM> comprises substrate <NUM>, fluidic layer <NUM>, drop generators <NUM>-<NUM>, <NUM>-<NUM> (collectively referred to as drop generators <NUM>) and fluid feed holes <NUM>-<NUM>, <NUM>-<NUM> (collectively referred to as holes <NUM>).

Substrate <NUM> comprises a structure through which fluid feed holes <NUM> extend. Substrate <NUM> may further provide a base or supporting structure for fluid actuators of drop generators <NUM>. In one implementation, substrate <NUM> comprises at least one layer of silicon. In other implementations, substrate <NUM> may be formed from other materials, such as ceramics, glass or the like.

Fluidic layer <NUM> comprises at least one layer of material disposed on substrate <NUM>. Fluidic layer <NUM> forms portions of drop generators <NUM>. In one implementation, fluidic layer <NUM> may be formed from materials that are easily patterned or shaped. In one implementation, fluidic layer <NUM> may comprise a photoresist material, such as a photoresist epoxy such as SU8. In other implementations, fluidic layer <NUM> may be formed from a polymer or other materials.

Drop generators <NUM> are formed in fluidic layer <NUM> and selectively eject droplets of fluid. Drop generators <NUM>-<NUM>, <NUM>-<NUM> comprise fluid ejection chambers <NUM>-<NUM>, <NUM>-<NUM> (collectively referred to as fluid ejection chambers <NUM>), ejection orifices are nozzles <NUM>-<NUM>, <NUM>-<NUM> (collectively referred to as nozzles <NUM>) and fluid actuators <NUM>-<NUM>, <NUM>-<NUM> (collectively referred to as fluid actuators <NUM>), respectively. Fluid ejection chambers <NUM> are formed by the materials or layer(s) of fluidic layer <NUM>. Fluid ejection chambers <NUM> are fluidly connected to one another by an intervening fluid passage <NUM>. Passage <NUM> facilitates fluid supplied by fluid feed hole <NUM>-<NUM> to flow to fluid ejection chamber <NUM>-<NUM> or fluid supplied by fluid feed hole <NUM>-<NUM> to flow to fluid ejection chamber <NUM>-<NUM>. As shown by broken lines, at least one support post <NUM> is formed within passage <NUM>. Support posts <NUM> extend between and are directly connected to portions of fluidic layer <NUM> forming nozzles <NUM> and substrate <NUM>. Support posts <NUM> support portions of fluidic layer <NUM> relative to substrate <NUM>. In other implementations, passage <NUM> may be omitted such that a post <NUM> extending between the portion of fluidic layer <NUM> forming nozzles <NUM> and substrate <NUM> completely separate and isolate chamber <NUM>-<NUM> from chamber <NUM>-<NUM>.

Fluid feed holes <NUM> are similar to fluid feed holes <NUM> except that fluid feed holes <NUM> are illustrated as being tapered. As with fluid feed holes <NUM>, fluid feed holes <NUM> comprise fluid passages that direct the flow of fluid to fluid ejection chambers <NUM>. Fluid feed holes <NUM> receive fluid from a single fluid supply passage <NUM> (schematically illustrated). In other words, each of fluid feed holes <NUM> has an inlet <NUM> that receives fluid from the same fluid supply <NUM>. In some implementations, fluid ejection device <NUM> may comprise multiple sets of fluid feed holes with each set of fluid feed holes (more than one fluid feed hole in each set) receiving fluid from or sharing a single fluid supply <NUM>. In some implementations, each fluid supply <NUM>, which supplies fluid to a respective set of fluid feed holes, may supply different fluids having different characteristics, such as different colors or other different properties.

Each of fluid feed holes <NUM> has an outlet port <NUM> directly connected to at least one ejection chamber <NUM>. Each outlet port is sized to pass bubbles out of or from the ejection chambers <NUM>. In the example illustrated, each outlet port is sized based upon a height H of the ejection chamber most proximate to the outlet port <NUM>. For example, in implementations where fluid ejection device <NUM> provides relatively high flow rates within fluid ejection chamber <NUM>, flow rates having a Reynolds number of greater than <NUM>, each outlet port <NUM> has a minimum dimension MD of at least <NUM> times the height. In implementations where fluid ejection device <NUM> provides slower flow rates within fluid ejection chamber <NUM>, flow rates having a Reynolds number of less than or equal to one, each outlet port <NUM> has a minimum dimension MD of at least two times the height H. The larger minimum dimension MD of outlet port <NUM> further facilitates the expulsion of bubbles in such low-flow fluid ejection devices where fluid pressure offers less assistance for expelling such bubbles throughout outlet port <NUM>.

<FIG> is a flow diagram of an example fluid supply and ejection method <NUM>. Method <NUM> facilitates the supply of fluid through individual fluid feed holes with a reduced likelihood of bubbles blocking or impeding the supply of fluid to fluid ejection chambers. Although method <NUM> is described in the context of being carried out by fluid ejection device <NUM>, it should be appreciated that method <NUM> may likewise be carried out with any of the following described fluid ejection devices or with similar fluid ejection devices and systems.

As indicated by block <NUM>, portions of the volume of fluid are distributed amongst different fluid feed holes extending through a substrate. As indicated by block <NUM>, the portions of the volume of fluid are directed through the fluid feed holes to a fluidic layer. As indicated by block <NUM>, each of the portion of the fluid is directed from the fluid feed holes through a port to a fluid ejection chamber having a height no greater than two thirds a minimum dimension of the port. As discussed above, this sizing of the ports of the fluid feed holes facilitates the passage of such bubbles away from the fluid ejection chambers through the fluid feed holes, reducing the likelihood that such bubbles may block the supply of fluid to the fluid ejection chambers.

<FIG> illustrates portions of a fluid ejection device <NUM> according to the invention. Fluid ejection device <NUM> comprises an elongated thin "sliver" fluid ejection die <NUM> molded into a monolithic body <NUM>, or molding <NUM>. In one implementation, the "sliver" fluid ejection die <NUM> has a length to width ratio of at least <NUM>:<NUM>. In yet other implementations, the sliver fluid ejection die <NUM> has a length to width ratio of at least <NUM>:<NUM> or at least <NUM>: <NUM>. Such length to width ratios may facilitate more compact fluid ejection devices and reduce die fabrication cost. The die <NUM> can be made of silicon. In yet other implementations, the die <NUM> may be formed from other materials.

The molding <NUM> can be formed of plastic, epoxy mold compound, or other moldable material. The fluid ejection die <NUM> is molded into the molding <NUM> such that a front surface of a fluidics layer <NUM> on the die <NUM> remains exposed outside of the molding <NUM>, enabling the die to dispense fluid. A substrate <NUM> forms the back surface <NUM> of the die <NUM> which is covered by the molding <NUM> except at a channel <NUM> formed in the molding <NUM>. The mold channel <NUM> enables fluid to flow directly to the die <NUM>. In different examples, a fluid ejection device <NUM> includes one or multiple fluid ejection dies <NUM> embedded within a monolithic molding <NUM>, with the fluid channel <NUM> formed in the molding <NUM> for each die <NUM> to carry fluid directly to the back surface <NUM> of the die <NUM>.

In some embodiments, the substrate <NUM> comprises a thin sliver in the order of <NUM> microns in thickness. In other implementations, the thickness may be on the order of <NUM> microns. The substrate <NUM> includes fluid feed holes <NUM> dry etched or otherwise formed in the substrate <NUM> to convey fluid through the substrate <NUM> from its back surface <NUM> to its front surface <NUM>. In some embodiments, the fluid feed holes <NUM> completely traverse a substrate <NUM> composed of bulk silicon. The fluid feed holes <NUM> are arranged in an array (i.e., a row or line) that may extend along a length (L) of the substrate <NUM>, parallel to the mold channel <NUM>, for example centered with respect to a width W2 of the mold channel <NUM>. In a further example the fluid feed hole array is also centrally located with respect to a width (W) of the substrate <NUM>. In other words, a line or row of fluid feed holes <NUM> may run down the center of the substrate <NUM> along its length (L). It is noted that the length (L) illustrated in <FIG>, for example, is not intended to illustrate the full length of the substrate <NUM>. Instead, the length (L) is intended to indicate the orientation of length to width of the substrate <NUM>. As noted above, <FIG> illustrate just a portion of an example molded fluid ejection device <NUM>. In many instances, the substrate <NUM> would be significantly longer than the length (L) and the number of fluid feed holes <NUM> would be significantly greater than the several that are illustrated. A single mold channel <NUM> in the mold <NUM> may supply fluid to the array of fluid feed holes <NUM>.

In the illustrated example, the fluid feed holes <NUM> include walls <NUM> that are tapered from the front surface <NUM> to the back surface <NUM> of the substrate <NUM>. Such tapered fluid feed holes <NUM> have a smaller or narrower cross section at the front surface <NUM> of the substrate <NUM> and they become increasingly larger or wider as they extend through the substrate <NUM> to the back surface <NUM>. In the illustrated example, the tapered fluid feed holes <NUM> help to manage air bubbles that develop in the fluid ejection device <NUM>. Ink or other liquids may contain varying amounts of dissolved air, and as fluid temperatures increase during fluid drop ejections, the solubility of air in the fluid decreases. The result can be a relatively few air bubbles in the ink or other liquid thereby inhibiting certain consequences of air bubbles in the liquid which may include faulty nozzle performance or reduced print quality. During fluid ejection, because nozzles <NUM> may be oriented below the fluid feed holes <NUM>, air bubbles developing in fluid ejection chambers <NUM> and elsewhere in the fluid ejection device <NUM> may tend to rise upwards through the fluid feed holes <NUM>. Such upward motion of the air bubbles away from the nozzles <NUM> and chambers <NUM> may be assisted by the widening taper <NUM> in the fluid feed holes <NUM> as well as by this sizing of the fluid feed holes <NUM> relative to the height of the fluid ejection chambers <NUM>.

In the example illustrated, each of the fluid feed holes <NUM> direct the flow of fluid to fluid ejection chambers <NUM>. Fluid feed holes <NUM> receive fluid from a single fluid supply passage <NUM>. In other words, each of fluid feed holes <NUM> has an inlet <NUM> that receives fluid from the same fluid supply <NUM>. In some implementations, fluid ejection device <NUM> may comprise multiple sets of fluid feed holes with each set of fluid feed holes (more than one fluid feed hole in each set) receiving fluid from or sharing a single fluid supply <NUM>. In some implementations, each fluid supply <NUM>, which supplies fluid to a respective set of fluid feed holes, may supply different fluids having different characteristics, such as different colors or other different properties.

As further shown by <FIG>, each of fluid feed holes <NUM> generally extends in a direction parallel to the direction in which fluid is ejected through nozzles <NUM>. In some implementations, each ejection chamber <NUM> may be supplied with fluid by several fluid feed holes <NUM>. In yet other implementations, a fluid feed hole <NUM> may supply fluid to more than one ejection chamber <NUM>.

Each of fluid feed holes <NUM> has an outlet port <NUM> directly connected to at least one ejection chamber <NUM>. Each outlet port <NUM> is sized to pass bubbles out of or from the ejection chambers <NUM>. In the example illustrated, each outlet port <NUM> is sized based upon a height H of the ejection chamber most proximate to the outlet port <NUM>. For example, in implementations where fluid ejection device <NUM> provides relatively high flow rates within fluid ejection chamber <NUM> (or within <NUM> from chamber <NUM>), flow rates having a Reynolds number of greater than <NUM>, each outlet port <NUM> has a minimum dimension MD of at least <NUM> times the height. In implementations where fluid ejection device <NUM> provides slower flow rates within fluid ejection chamber <NUM> (or within <NUM> from chamber <NUM>), flow rates having a Reynolds number of less than or equal to one, each outlet port <NUM> has a minimum dimension MD of at least two times the height H. The larger minimum dimension MD of outlet port <NUM> further facilitates the expulsion of bubbles in such low-flow fluid ejection devices where fluid pressure offers less assistance for expelling such bubbles throughout outlet port <NUM>.

The substrate <NUM> also includes ribs <NUM> or bridges that traverse the fluid channel <NUM> between the fluid feed holes <NUM> on either side of the fluid feed holes <NUM>. The ribs <NUM> may result from the formation and presence of the fluid feed holes <NUM>. Each rib <NUM> is positioned between two fluid feed holes <NUM> and extends widthwise across the substrate <NUM> as it traverses the underlying fluid channel <NUM> formed in the molding <NUM>. In an example, the substrate is made of bulk silicon and the ribs <NUM> are part of the bulk silicon, traversing part of the molded channel of the mold <NUM>.

In <FIG>, a dashed line C-C indicates a cross-sectional view of the fluid ejection device <NUM> as illustrated in <FIG>. The cross-sectional view of fluid ejection device <NUM> in <FIG> illustrates a silicon rib <NUM> that extends between fluid feed holes <NUM> and a front and back surface <NUM>, <NUM> of the substrate <NUM>. The partially dashed line <NUM> in <FIG> represents the outline of a tapered fluid feed hole wall <NUM> behind (or in front of) the silicon rib <NUM>. The widening taper <NUM> of the fluid feed holes <NUM> from the front surface <NUM> to the back surface <NUM> of the substrate <NUM> causes a narrowing of the ribs <NUM> as the ribs extend from the front surface to the back surface.

The fluid feed holes <NUM> with interleaved ribs <NUM> traversing the fluid channel <NUM> provide increased strength and mechanical stability to the fluid ejection die <NUM>. This allows the die <NUM> to be made smaller than conventional fluid ejection dies having fluid slots cut completely through a silicon substrate.

In some embodiments, the reduced die size may increase nozzle and drop generator density. By bringing opposite drop generators <NUM> (i.e. ejection chambers, resistors and nozzles) in opposite drop generator arrays closer to one another, the fluid ejection die <NUM> can be made of a relatively small width (W). For example, the reduction in die size of the fluid ejection die <NUM> in a molded fluid ejection device <NUM> according to some embodiments may, when compared to a silicon printhead with longitudinal fluid slot, can be in the order of two to four times. For example, some of such printheads with longitudinal fluid feed slots can support two parallel nozzle arrays on a silicon die having width of approximately <NUM> microns, the fluid ejection die "sliver"-in-mold according to some embodiments can support two opposite, parallel nozzle arrays on a silicon die <NUM> having a width W of approximately <NUM> microns. In different examples the width W of the die <NUM> may be between approximately <NUM> and <NUM> microns. In further examples one or two nozzle arrays are disposed within <NUM> microns of substrate width W.

As illustrated in <FIG> and <FIG>, formed on the front surface <NUM> of substrate <NUM> is a fluidics layer <NUM>. The fluidics layer <NUM> generally defines a fluidic architecture that includes fluid drop generators <NUM>, pillar structures <NUM>, <NUM>, and a manifold channel or manifold <NUM>. Each fluid drop generator <NUM> includes a fluid ejection chamber <NUM>, a nozzle <NUM>, a chamber inlet <NUM>, and an ejection element <NUM> formed on the substrate <NUM> that can be activated to eject fluid from the chamber <NUM> through the nozzle <NUM>. A common manifold fluidically links each fluid feed hole <NUM> to the inlets <NUM>. In the illustrated example, two rows of drop generators <NUM> extend lengthwise at either side of the fluid feed hole array, parallel to the fluid feed hole array.

In different implementations, the fluidics layer <NUM> may comprise a single monolithic layer or it may comprise multiple layers. For example, the fluidics layer <NUM> may be formed of both a chamber layer <NUM> (also referred to as a barrier layer) and a separately formed nozzle layer <NUM> (also referred to as a top hat layer) over the chamber layer <NUM>. All or a substantial portion of the layer or layers making up the fluidics layer <NUM> can be formed of an SU8 Epoxy or some other polyimide material, and can be formed using various processes including a spin coating process and a lamination process.

In a further example a location and pitch of each fluid feed hole <NUM> of the array is such that a center of each fluid feed hole <NUM> extends approximately between the centers of the closest ejection chambers <NUM> at either side. For example, if in a top view (e.g. <FIG>), one would draw a straight line SL through nearest center points of approximately opposite nozzles <NUM>, then the straight line SL would cross the center of the fluid feed hole <NUM> between these nozzles <NUM>, or a center of a rib <NUM>. In a further example, in a top view (e.g. <FIG>), in a die <NUM>, any line (e.g. SL) that can be drawn through a center of a fluid feed hole <NUM> and a center of an ejection chamber <NUM> is not parallel to a media advance direction.

During printing or other fluid ejections, fluid is ejected from the ejection chambers <NUM> through corresponding nozzles <NUM> and is replenished with fluid from the mold channel <NUM>. Fluid from the channel <NUM> flows through the feed holes <NUM> and into the manifold <NUM>. From the manifold <NUM>, fluid flows through the chamber inlets <NUM> into the ejection chambers <NUM>. Printing speeds can be increased by rapidly refilling the ejection chambers <NUM> with fluid. However, as fluid flows towards and into the chambers <NUM>, small particles in the fluid can get lodged in and around the chamber inlets <NUM> that lead to the chambers <NUM>. These small particles can diminish and/or completely block the flow of fluid to the chambers, which can result in the premature failure of the ejection elements <NUM>, reduced ink drop size, misdirected ink drops, and so on. Pillar structures <NUM> near the chamber inlets <NUM> provide for a particle-tolerant architecture (PTA) that may serve, at least in part, as a barrier to prevent particles from blocking or passing through the chamber inlets <NUM>. The placement, size, and spacing of the PTA pillars <NUM> are generally designed to prevent particles, even of a relatively small size, from blocking the inlets <NUM> to the ejection chambers <NUM>. In the illustrated example the PTA pillars <NUM> are disposed adjacent to the inlet. For example, two PTA pillars <NUM> can be provided at a distance to the inlet opening of approximately two times a pillar diameter or less, or approximately one time a pillar diameter or less. In a further example, at least one PTA pillar <NUM> is disposed in an inlet bay <NUM> into which an inlet <NUM> opens. In such example, inlet bay <NUM> arrays may be provided in the manifold side walls, between the manifold <NUM> and each inlet <NUM>. In other examples, one or three PTA pillars <NUM> or more can be provided near the inlet <NUM>, to inhibit migration of particles towards the chambers <NUM>.

In a further example, the inlet <NUM> to the chamber <NUM> is pinched, that is, a maximum width W4 of each inlet <NUM> is less than a diameter D of each corresponding chamber <NUM>, wherein the direction of the measured width W4 and diameter D is parallel to a length axis of the manifold <NUM> or to the length axis of the fluid feed hole array. For example, the maximum width W4 of the inlet <NUM> is less than two third of a diameter D of the chamber. In some embodiments, the pinch point may reduce cross talk. In another example, the pinched inlet may reduce influences of variations in fluid feed hole size, position or lengths.

Additional pillar structures <NUM> comprise bubble-tolerant architectures <NUM> (BTA) that are generally configured to impede the movement of air bubbles through the die manifold <NUM> and to guide air bubbles into the tapered fluid feed holes <NUM> where they can float upward and away from the downward facing drop generator nozzles <NUM>. The BTA pillars <NUM> can be disposed in the manifold <NUM> between the fluid feed hole openings <NUM> on top of the ribs <NUM>. In an example, the BTA pillars <NUM> may have a larger volume or width than the PTA pillars <NUM>. For example, the BTA pillars may have a width W3 that is at least half the diameter of the fluid feed hole opening <NUM> into the manifold <NUM>, for example approximately the same as the diameter of the fluid feed hole opening <NUM> into the manifold <NUM>. It is noted that although in this illustrative description it has been chosen to denominate the pillars <NUM>, <NUM> as "PTA" and "BTA" pillars, in different examples the functions and advantages of the pillars <NUM>, <NUM> may vary and are not necessarily (only) related to the particles or bubbles, respectively, but may have additional or different functions and advantages.

In further examples the pillar structures <NUM>, <NUM> serve the purpose of mitigating fluidic cross-talk between neighboring drop generators <NUM> that are in close proximity with one another, for example in addition to, or instead of, mitigating a negative influence of bubbles and/or particles. As previously noted, a smaller fluid ejection die <NUM> in the molded fluid ejection device <NUM> is enabled in part by the presence of fluid feed holes <NUM> and the associated ribs <NUM> that traverse the fluid channel <NUM> and add strength to the substrate <NUM>. The reduced die size increases nozzle and drop generator density by bringing drop generators closer to one another across the channel <NUM> and width (W) of the substrate <NUM>. The relatively high nozzle density in the fluid ejection device <NUM> could result in a relatively high level of fluidic cross-talk between neighboring drop generators <NUM>. That is, as fluid drop generators are brought in closer proximity to one another, increasing fluidic cross-talk between neighboring ejection chambers can cause fluid pressure and/or volume changes in the chambers that may adversely impact drop ejections. In certain examples, the pillar structures <NUM>, <NUM> structures in the fluidics layer <NUM> may serve to mitigate the impact of fluidic cross-talk.

The fluid ejection device <NUM> includes the fluid channel <NUM> who serves as a single fluid supply passage from multiple fluid feed holes <NUM>. The fluid channel <NUM> is formed through molded body <NUM> to enable fluid to flow directly onto the silicon substrate <NUM> at the back surface <NUM>, and into the substrate <NUM> through the fluid feed holes <NUM>. The fluid channel <NUM> can be formed in the molded body <NUM> in a number of ways. For example, a rotary or other type of cutting saw can be used to cut and define the channel <NUM> through the molded body <NUM> and a thin silicon cap (not shown) over the feed holes <NUM>. Using saw blades with differently shaped peripheral cutting edges and in varying combinations, channels <NUM> can be formed having varying shapes that facilitate the flow of fluid to the back surface <NUM> of the substrate. In other examples, at least part of the channel <NUM> can be formed as the fluid ejection die <NUM> is being molded into the molded body <NUM> of the fluid ejection device <NUM> during a compression or transfer molding process. A material ablation process (e.g., powder blasting, etching, lasering, milling, drilling, electrical discharge machining) can then be used to remove residual molding material. The ablation process may enlarge the channel <NUM> and complete the fluid pathway through the molded body <NUM> to the fluid feed holes <NUM>. When a channel <NUM> is formed using a molding process, the shape of the channel <NUM> generally reflects the inverse shape of the mold chase topography being used in the process. Accordingly, varying the mold chase topographies can yield a variety of differently shaped channels that facilitate the flow of fluid to the back surface <NUM> of the silicon substrate <NUM>.

As noted above, the molded fluid ejection device <NUM> is suitable for use in, for example, a replaceable fluid ejection cartridge and/or a media-wide fluid ejection assembly ("print bar") of a 2D or 3D printer. <FIG> is a block diagram illustrating an example of a printer <NUM> with a replaceable print cartridge <NUM> that incorporates an example fluid ejection device <NUM>, the fluid ejection device including a molding <NUM> and a die <NUM> embedded in the molding <NUM>. The die includes fluid feed holes <NUM>. In an example the printer is an inkjet printer and the cartridge <NUM> includes at least one ink compartment <NUM> that is at least partially filled with ink. Different compartments may hold different colors of ink. In some embodiments of the printer <NUM>, a carriage <NUM> scans print cartridge <NUM> back and forth over a print media <NUM> to apply ink to media <NUM> in a desired pattern. During printing, a media transport assembly <NUM> moves print media <NUM> relative to the print cartridge <NUM> to facilitate the application of ink to media <NUM> in a desired pattern. Controller <NUM> generally includes a processor, memory, electronic circuitry and other components to control the operative elements of the printer <NUM>. The memory stores instructions to control the operative elements of the printer <NUM>.

<FIG> illustrates a perspective view of an example print cartridge <NUM>. The print cartridge <NUM> includes a molded fluid ejection device <NUM> supported by a cartridge housing <NUM>. Fluid ejection device <NUM> includes four elongated fluid ejection dies <NUM> and a PCB (Printed Circuit Board) <NUM> mounted to a molding <NUM>. As shown by <FIG>, molding <NUM> comprises a molded structure that includes an elongate channel or fluid supply passage <NUM> for supplying fluid to the fluid feed holes of a die. In the example illustrated in which fluid ejection device <NUM> includes four fluid ejection dies <NUM>, molding <NUM> comprises at least four fluid supply passages <NUM>, at least one fluid supply passage <NUM> for each of the four fluid ejection dies <NUM>. In the example illustrated, each of the four dies is embedded in the molding <NUM>, wherein fluid supply passage is part of the molded structure and the fluid feed holes are part of the die. In one implementation, the molded structure provided by molding <NUM> at least partially encapsulates each of the dies <NUM>.

The PCB may include electric and electronic circuitry such as drive circuitry to drive the fluid ejection elements in each die <NUM>. In the illustrated example, the fluid ejection dies <NUM> are arranged parallel to one another across the width of fluid ejection device <NUM>. The four fluid ejection dies <NUM> are located within a window <NUM> that has been cut out of PCB <NUM>. While a single fluid ejection device <NUM> with four dies <NUM> is illustrated for print cartridge <NUM>, other configurations are possible, for example with more fluid ejection devices <NUM> each with more or fewer dies <NUM>.

The print cartridge <NUM> can be electrically connected to the controller <NUM> through electrical contacts <NUM>. In an example, the contacts <NUM> are formed in a flex circuit <NUM> affixed to the housing <NUM>, for example along one of the outer faces of the housing <NUM>. Signal traces embedded in flex circuit <NUM> may connect the contacts <NUM> to corresponding circuitry on the fluid ejection die <NUM>, for example through bond wires covered by a low profile protective cover <NUM> at the extremes of the fluid ejection dies <NUM>. In an example, ejection nozzles on each fluid ejection die <NUM> are exposed through an opening in, or next to an edge of, the flex circuit <NUM> along the bottom of cartridge housing <NUM>.

<FIG> illustrates a perspective view of another example print cartridge <NUM> suitable for use in a printer <NUM> or any other suitable high precision digital dispensing device. In this example, the print cartridge <NUM> includes a media wide fluid ejection assembly <NUM> with four fluid ejection devices <NUM> and a PCB <NUM> mounted to a molding <NUM> and supported by the cartridge housing <NUM>. Each fluid ejection device <NUM> includes four fluid ejection dies <NUM> and is located within a window <NUM> cut out of the PCB <NUM>.

As shown by <FIG>, molding <NUM> comprises a molded structure that includes an elongate channel or fluid supply passage <NUM> for supplying fluid to the fluid feed holes of a die. In the example illustrated in which each fluid ejection device <NUM> includes four fluid ejection dies <NUM>, molding <NUM> comprises at least four fluid supply passages <NUM>, at least one fluid supply passage <NUM> for each of the four fluid ejection dies <NUM>. In the example illustrated, each of the four dies <NUM> is embedded in the molding <NUM>, wherein fluid supply passage is part of the molded structure and the fluid feed holes are part of the die. In one implementation, the molded structure provided by molding <NUM> at least partially encapsulates each of the dies <NUM>.

While a printhead assembly <NUM> with four fluid ejection devices <NUM> is illustrated for this example print cartridge <NUM>, other configurations are possible, for example with more or fewer fluid ejection devices <NUM> that each have more or fewer dies <NUM>. At each back side of each die <NUM>, a mold channel may be provided through the molding <NUM> to supply fluid to a fluidics layer of each die. At either end of the fluid ejection dies <NUM> in each fluid ejection device <NUM> bond wires may be provided, for example covered by a low profile protective coverings <NUM> comprising a suitable protective material such as an epoxy, and a flat cap placed over the protective material. Electrical contacts <NUM> are provided to electrically connect the fluid ejection assembly <NUM> to a printer controller <NUM>. The electrical contacts <NUM> may connect to traces embedded in a flex circuit <NUM>.

<FIG> is a block diagram illustrating a printer <NUM> with a fixed media wide fluid ejection assembly <NUM> implementing another example of a molded fluid ejection device <NUM>. Printer <NUM> includes media wide fluid ejection assembly <NUM> spanning the width of a print media <NUM>, a fluid delivery system <NUM> associated with fluid ejection assembly <NUM>, a media transport mechanism <NUM>, a receiving structure for fluid supplies <NUM>, and a printer controller <NUM>. Controller <NUM> includes a processor, a memory having control instructions stored thereon, and electronic circuitry and components needed to control the operative elements of a printer <NUM>. The fluid ejection assembly <NUM> includes an arrangement of fluid ejection dies <NUM> for dispensing fluid on to a sheet or continuous web of paper or other print media <NUM>. In operation, each fluid ejection die <NUM> receives fluid through a flow path that runs from supplies <NUM> into, through the fluid delivery system <NUM> and fluid channels <NUM> into the fluid ejection dies <NUM>.

<FIG> and <FIG> illustrate perspective views of a molded media-wide fluid ejection assembly <NUM> with multiple fluid ejection devices <NUM>, for example for inclusion in a print cartridge, page wide array print bar or printer. <FIG> illustrates a different, section view of <FIG>. The molded fluid ejection assembly <NUM> includes multiple fluid ejection devices <NUM> and a PCB <NUM> that are both mounted to a molding <NUM>.

As shown by <FIG>, molding <NUM> comprises a molded structure that includes an elongate channel or fluid supply passage <NUM> for supplying fluid to the fluid feed holes of a die. In the example illustrated in which each fluid ejection device <NUM> includes four fluid ejection dies <NUM>, molding <NUM> comprises at least four fluid supply passages <NUM>, at least one fluid supply passage <NUM> for each of the four fluid ejection dies <NUM>. In the example illustrated, each of the four dies is embedded in the molding <NUM>, wherein fluid supply passage is part of the molded structure and the fluid feed holes are part of the die. In the example illustrated, the molded structure provided by molding <NUM> at least partially encapsulates each of the dies <NUM>. In the example illustrated, molded structure or molding <NUM> encapsulates the parallel and end aligned dies <NUM> of each set of four dies as well as the staggered sets themselves.

Claim 1:
A fluid ejection device (<NUM>; <NUM>; <NUM>) comprising:
fluid actuators (<NUM>; <NUM>);
ejection chambers (<NUM>; <NUM>) adjacent the fluid actuators (<NUM>-<NUM>, <NUM>-<NUM>; <NUM>);
nozzles (<NUM>; <NUM>) extending from the ejection chambers (<NUM>; <NUM>);
a substrate (<NUM>; <NUM>);
tapered fluid feed holes (<NUM>; <NUM>) to supply fluid from a fluid supply passage (<NUM>; <NUM>) to the ejection chambers (<NUM>; <NUM>), the fluid feed holes (<NUM>; <NUM>) having ports (<NUM>; <NUM>) connected to the ejection chambers (<NUM>; <NUM>), the ports (<NUM>; <NUM>) being dimensioned to pass bubbles out of the ejection chambers (<NUM>; <NUM>); and
a fluidic layer (<NUM>; <NUM>) disposed on the substrate (<NUM>; <NUM>), wherein the ejection chambers (<NUM>; <NUM>) are formed in the fluidic layer (<NUM>; <NUM>) and have a height; and wherein the fluid feed holes (<NUM>; <NUM>) extend through the substrate (<NUM>; <NUM>) from the fluid supply passage (<NUM>; <NUM>), the ports (<NUM>; <NUM>) connected to at least one of the ejection chambers (<NUM>; <NUM>), the ports (<NUM>; <NUM>) having a minimum dimension (MD) of at least <NUM> times the height (H).