Patent Description:
Document <CIT> discloses a fluid ejection device comprising filtering means to capture air bubbles or foreign materials.

are not necessarily to scale, and the size of some parts may be exaggerated to more clearly illustrate the example shown.

Claim <NUM> discloses a fluid ejection and circulation apparatus, claim <NUM> discloses a fluid ejection and circulation method. The example apparatus, systems and methods circulate the fluid being supplied to a fluid ejection device across a chamber of a pressure regulator, prior to the fluid passing from the pressure regulator through a filter and to the fluid ejection device. Such circulation of the fluid may inhibit settling of fluid suspended particles, enhancing fluid ejection performance and facilitating the use of fluids having heavier particles and/or a higher concentration of particles.

For example, in implementations where the example fluid ejection circulation apparatus and methods are used to selectively eject droplets of printing fluid, such as ink, the apparatus and methods facilitate the use of pigment-based inks having a higher concentration of pigments and/or heavier, possibly metallic, pigments. Pigment-based inks tend to be more efficient, durable and permanent as compared to dye-based inks. Such pigments may be especially beneficial in the composition of a white ink, wherein the heavier metallic pigments and/or higher concentration of such pigments provide the white ink with a greater opacity and/or brightness. With such inks, the circulation of the fluid reduces settling of the pigments, enhancing printing performance and/or prolonging life of the fluid ejection device. Without such circulation, pigment settling may block ink flow and clogged nozzles, especially during periods of storage or nonuse of printing apparatus.

The disclosed fluid ejection and circulation apparatus may provide macro recirculation. Such macro recirculation utilizes a pressure regulator that finally controls the port pressure of the fluid flowing to the fluid ejection device. Such macro recirculation continually refreshes the fluid, reducing air and particulate levels near the fluid ejection device. As a result, fluid ejection or printing reliability is enhanced.

In some implementations, the pressure regulator maintains fluid backpressure in the ejection chamber of the fluid ejection device within a narrow range below atmospheric levels in order to avoid depriming of the nozzles or ejection orifices (leading to drooling or fluid leaking) while optimizing fluid ejection device pressure conditions for fluid ejection or printing. During non-operational periods, this pressure is maintained statically by surface tension of fluid in the ejection orifices. The pressure regulator may operate by using a formed metal spring to apply a force to an area of flexible or compliant film or chamber attached to the perimeter of the regulator chamber that is open to the atmosphere, thereby establishing a negative internal pressure for fluid containment in the apparatus. A lever on a pivot point connects the metal spring assembly to a valve such that deflection of the spring can either open or close the valve by mating it to a valve seat.

During operation, fluid is expelled from the printhead, which evacuates ink from the pressure-controlled fluid containment system of the regulator. When the pressure in the regulator reaches the backpressure set point established through design choices for spring force (i.e., spring constants K) and flexible film area, the valve opens and allows ink to be delivered from a pump connected to the port of the pressure regulator. Once a sufficient volume of ink is delivered, the spring expands and closes the valve. The regulator operates from fully open to fully closed (i.e., seated) positions. Positions in between the fully open and fully closed positions modulate the pressure drop through the regulator valve itself, causing the valve to act as a flow control element.

Disclosed is an example fluid ejection and circulation apparatus that may include a fluid ejection device, a filter to filter fluid supplied to the fluid ejection device and a pressure regulator. The pressure regulator may include a fluid chamber having a fluid port and a first port extending from the fluid chamber to the filter. The pressure regulator may further include a valve to open and close the fluid port and a compliant chamber within the fluid chamber. The compliant chamber is to undergo different inflation levels in response to fluid chamber pressure. The valve is to open and close the fluid port in response to changes in an inflation level of the compliant chamber. The fluid chamber comprises a second port cooperating with the first port to form a circulation path through the fluid chamber that is directed away from the filter.

Disclosed is an example fluid ejection and circulation system that may comprise a first fluid ejection device, a second fluid ejection device, a first pressure regulator and a second pressure regulator. The first pressure regulator may comprise a first fluid chamber having a first port and a first interior connected to the first fluid ejection device. A first compliant chamber may be provided within the first fluid chamber, wherein the compliant chamber has an inflation level that changes in response to first fluid chamber pressure. A valve may open and close the first port in response to an inflation level of the first compliant chamber.

The second pressure regulator may comprise a second fluid chamber having a second port and a second interior connected to the second fluid ejection device. The second compliant chamber within the second fluid chamber has an inflation level that changes in response to second fluid chamber pressure. A second valve may open and close the second port in response to an inflation level of the second compliant chamber. The second fluid chamber may be connected to the first fluid chamber by a third port to provide circulation from the first pressure regulator to the second pressure regulator.

Disclosed is an example fluid circulation method that may include supplying fluid to a fluid chamber of a pressure regulator and circulating the fluid through and out of the fluid chamber away from an underlying filter. In some implementations, the fluid is circulated away from the underlying filter into the fluid chamber of a second pressure regulator. In some implementations, the fluid is pulled out of the fluid chamber of the second pressure regulator while the fluid is pumped into the fluid chamber of the pressure regulator. In some implementations, an actuator is used to open a valve of the second pressure regulator to facilitate the pulling of the fluid from the fluid chamber of the second pressure regulator. In some implementations, the actuator comprises a pump or inflator that inflates a compliant chamber of the second pressure regulator to open the valve.

<FIG> schematically illustrates portions of an example fluid ejection and circulation apparatus <NUM> for the controlled ejection of fluid, wherein the fluid may be circulated within the apparatus to further mix particles suspended within the fluid to reduce settling of the particles. Apparatus <NUM> circulates the fluid across the chamber of a pressure regulator, prior to the fluid passing through the filter. Apparatus <NUM> comprises fluid ejection device <NUM>, filter <NUM> and pressure regulator <NUM>.

Fluid ejection device <NUM> controls the ejection of fluid from apparatus <NUM>. Fluid ejection device <NUM> may include a fluid actuator adjacent an ejection chamber that displaces fluid within the ejection chamber through a corresponding ejection orifice or nozzle. In one implementation, the fluid actuator may comprise a thermal resistor which, upon receiving electrical current, heats to a temperature above the nucleation temperature of the solution so as to vaporize a portion of the adjacent solution or fluid to create a bubble which displaces fluid through the orifice. In other implementations, the fluid actuator may comprise other forms of fluid actuators. In other implementations, the fluid actuator may comprise a fluid actuator in the form of a piezo-membrane based actuator, an electrostatic membrane actuator, mechanical/impact driven membrane actuator, a magnetostrictive drive actuator, an electrochemical actuator, and external laser actuators (that form a bubble through boiling with a laser beam), other such microdevices, or any combination thereof. Although apparatus <NUM> is illustrated as including a single fluid ejection device <NUM>, in other implementations, apparatus <NUM> may comprise multiple fluid ejection devices such as where multiple fluid ejection devices <NUM> are provided by a fluid ejection die having rows or columns of ejection chambers, nozzles and fluid actuators. For purposes of this disclosure, references to "a fluid ejection die" may refer to a single fluid ejection die or multiple fluid ejection dies, but for ease of explanation, the singular case is used to cover both.

Filter <NUM> comprises a porous structure through which fluid passes from pressure regulator <NUM> to fluid ejection device <NUM>. Filter <NUM> removes contaminants or other unwanted particles from the fluid being supplied to fluid ejection device <NUM>.

Pressure regulator <NUM> regulates the pressure of fluid being supplied to fluid ejection device <NUM>. Pressure regulator <NUM> comprises fluid chamber <NUM>, compliant chamber <NUM> and valve <NUM>. Fluid chamber <NUM> contains compliant chamber <NUM>. Fluid chamber <NUM> comprises port <NUM>, flow passage <NUM> and port <NUM>.

Port <NUM> comprises an opening within fluid chamber <NUM> communicating with an interior <NUM> of fluid chamber <NUM>. Port <NUM> is connectable to a source of fluid which may be pumped into interior <NUM>.

Flow passage <NUM> comprises a fluid connection between the interior <NUM> of fluid chamber <NUM> and filter <NUM>. In one implementation, the flow passage <NUM> may be formed by an open-ended bottom of fluid chamber <NUM> which overlies filter <NUM>. In another implementation is a flow passage <NUM> may comprise a differently sized opening or conduit leading to filter <NUM>. Flow passage <NUM> allows the flow of fluid from the interior <NUM> through filter <NUM> to fluid ejection device <NUM>.

Port <NUM> comprises an opening within fluid chamber <NUM> that allows fluid to flow out of fluid chamber <NUM> away from filter <NUM>. Port <NUM> facilitates the circulation of fluid through, across and out of fluid chamber <NUM> without the fluid being directed to or towards filter <NUM>. As a result, port <NUM> facilitates circulation mode in which fluid may be circulated through fluid chamber <NUM> of pressure regulator <NUM> to agitate or mix suspended particles or pigments without the fluid having to flow through filter <NUM> for such circulation. The fluid discharged from fluid chamber <NUM> during the circulation mode may be returned via port <NUM>.

According to the invention, port <NUM> is positioned proximate to flow passage <NUM> and proximate to filter <NUM> to provide a greater degree of fluid flow adjacent to and along filter <NUM>. As a result, the higher concentration of particle sediment collecting near flow passage <NUM> and filter <NUM> may be stirred or mixed and resuspended. In one implementation, port <NUM> has a mouth having a lower edge spaced no greater than <NUM> above the passage <NUM> or no greater than <NUM> above the top surface of filter <NUM>. In one implementation, the lower edge of port <NUM> is flush with the top surface of filter <NUM>.

Compliant chamber <NUM> may comprise a flexible membrane, pouch, bag or other structure which may change in shape and volume in response to pressure changes within fluid chamber <NUM>. In one implementation, compliant chamber <NUM> may comprise a flexible film along the internal sides of fluid chamber <NUM>, the film forming a compliant chamber that is connected to atmosphere. In another implementation, compliant chamber <NUM> may comprise an inflatable bag captured between a pair of resiliently biased levers.

Valve <NUM> comprise a valve mechanism that selectively opens and closes port <NUM> in response to or based upon the inflation level, shape or size of compliant chamber <NUM> which is itself dependent upon the fluid pressure level within interior <NUM> of fluid chamber <NUM>. As schematically illustrated by line <NUM>, valve <NUM> is actuatable based upon the inflation level of compliant chamber <NUM>. In one implementation, changes in the shape, size or inflation level of compliant chamber <NUM> move a lever which transmits the force to valve <NUM> to actuate valve <NUM>. In another implementation, the size, shape or inflation level of compliant chamber <NUM> may be sensed, wherein the sensed inflation level causes a controller to output control signals to an actuator actuating valve <NUM>.

In one implementation, pressure regulator <NUM> maintains fluid backpressure in the fluid ejection device <NUM> within a narrow range below atmospheric levels in order to avoid depriming of the nozzle or nozzles (leading to drooling or fluid leaking) while optimizing fluid ejection device pressure conditions for fluid ejection or printing. During non-operational periods, this pressure is maintained statically by surface tension of fluid in the nozzle. In some implementations, the pressure regulator <NUM> may operate by using a formed metal spring (not shown) to apply a force to an area of flexible or compliant film or chamber <NUM> that is open to the atmosphere, thereby establishing a negative internal pressure for fluid containment in the apparatus <NUM>. A lever (not shown) on a pivot point connects the metal spring assembly to a valve (not shown) that opens and closes port <NUM> such that deflection of the spring can either open or close the valve by mating it to a valve seat.

During operation in a fluid ejection mode, fluid flows along ejection path <NUM> (shown in broken lines) from interior <NUM>, through filter <NUM> and through fluid ejection device <NUM>. Fluid is expelled from the apparatus <NUM>, which evacuates fluid from the pressure-controlled fluid containment system of the regulator <NUM>. When the pressure in the regulator <NUM> reaches the backpressure set point established through design choices for spring force (i.e., spring constants K) and flexible film area, the valve <NUM> opens and allows fluid to be delivered from a pump connected to the port of the pressure regulator. Once a sufficient volume of fluid is delivered, the spring expands and closes the valve <NUM>. The regulator <NUM> operates from fully open to fully closed (i.e., seated) positions. Positions in between the fully open and fully closed positions modulate the pressure drop through the regulator valve itself, causing the valve to act as a flow control element.

In one implementation, pressure regulator <NUM> may be actuated to a circulation mode. During the circulation mode, fluid is not ejected by fluid ejection device <NUM>. In contrast, the fluid is circulated through port <NUM> along the illustrated circulation path <NUM>, without being directed to filter <NUM>. In one implementation, the fluid may be pulled from the interior <NUM> of fluid chamber <NUM> through port <NUM>. The fluid circulated through port <NUM> may be recirculated back into fluid chamber <NUM> for subsequent ejection. The circulation of fluid through, across and out of fluid chamber <NUM>, without passing through filter <NUM>, may serve to agitate or mix particle suspended within the fluid to delay or inhibit settling of the particles. Because such circulation occurs within fluid chamber <NUM>, the fluid being circulated does not pass through filter <NUM>, inhibiting settling of particles within or on filter <NUM>. As a result, the life of filter <NUM> may be extended. Moreover, because such circulation occurs above filter <NUM> or within chamber <NUM>, such circulation may be less susceptible to pressure spikes, enhancing the performance of apparatus <NUM>.

<FIG> is a flow diagram illustrating portions of an example fluid circulation method <NUM>. Method <NUM> circulates fluid within and across the fluid chamber of a pressure regulator to further mix particles suspended within the fluid to reduce settling of the particles, increasing the robustness of apparatus <NUM>. Although method <NUM> is described in the context of being carried out by apparatus <NUM>, it should be appreciated that method <NUM> may likewise be carried out with any of the systems or apparatus disclose hereafter or with similar systems or apparatus.

As indicated by block <NUM>, fluid is supplied to fluid chamber <NUM> of pressure regulator <NUM>. In one implementation, the fluid being supplied may comprise a fluid having larger or heavier particles or a higher concentration of particles that may be more prone to settling. For example, in one implementation, the fluid being supplied may comprise a printing fluid, such as an ink, containing heavier pigments or a higher concentration of pigments that may render the ink more susceptible to pigment settling. In one implementation, the printing fluid may comprise a white ink having heavier metallic particles or a higher concentration of metallic particles that provide the white ink with enhanced white color.

As indicated by block <NUM>, the fluid may be circulated through and out of the fluid chamber <NUM> away from the underlying filter <NUM>. In other words, the fluid flow is not directed towards filter <NUM> or through filter <NUM>. Such circulation of fluid through, cross and out of fluid chamber <NUM>, without being directed towards filter <NUM>, may occur during a circulation mode at times during which fluid is not being supplied to ejection chamber <NUM> through flow passage <NUM>. Such circulation agitates or mixes suspended particles within the fluid to reduce or inhibit settling of the particles. By reducing settling of the particles, nozzle or orifice health is maintained and fluid ejection performance is enhanced.

<FIG> schematically illustrates portions of an example fluid ejection and circulation apparatus <NUM>. Apparatus <NUM> provides controlled ejection of fluid, wherein the fluid may be circulated within the apparatus to further mix particles suspended within the fluid to reduce settling of the particles. Apparatus <NUM> circulates the fluid across the chambers of two pressure regulators, prior to the fluid passing through a filter. In one implementation, apparatus <NUM> may be formed as part of a fluid ejection unit or cartridge. Apparatus <NUM> comprises fluid ejection devices <NUM>-<NUM>, <NUM>-<NUM> (collectively referred to as fluid ejection devices <NUM>), filters <NUM>-<NUM>, <NUM>-<NUM> (collectively referred to as filters <NUM>) and pressure regulators <NUM>-<NUM>, <NUM>-<NUM> (collectively referred to as pressure regulators <NUM>).

Each of fluid ejection device <NUM> controls the ejection of fluid from apparatus <NUM>. Each of fluid ejection devices <NUM> is similar to fluid ejection device <NUM> described above. Each of fluid ejection device <NUM> comprises an ejection chamber <NUM> and a fluid actuator <NUM>. In the example illustrated, fluid ejection device <NUM>-<NUM> receives fluid that that has passed through pressure regulator <NUM>-<NUM> and through filter <NUM>-<NUM>. Fluid ejection device <NUM>-<NUM> receives fluid that is passed through pressure regulator <NUM>-<NUM> and through filter <NUM>-<NUM>.

Filters <NUM> are each similar to filter <NUM> described above. Each of filters <NUM> comprises a porous structure through which fluid passes from a respective pressure regulator <NUM> to a respective fluid ejection device <NUM>. Filters <NUM> remove contaminants or other unwanted particles from the fluid being supplied to fluid ejection devices <NUM>. Although illustrated as two separate components. In some implementations, filters <NUM>-<NUM> and <NUM>-<NUM> may be provided by a single unitary fluid filtering structure. In some implementations, filters <NUM> may be omitted.

Pressure regulators <NUM>-<NUM>, <NUM>-<NUM> regulate the pressure of fluid being supplied to fluid ejection devices <NUM>-<NUM>, <NUM>-<NUM>. Each of pressure regulators <NUM> is similar to pressure regulator <NUM> described above. Pressure regulators <NUM>-<NUM>, <NUM>-<NUM> comprise fluid chamber <NUM>-<NUM>, <NUM>-<NUM>, compliant chambers <NUM>-<NUM>, <NUM>-<NUM> and valves <NUM>-<NUM>, <NUM>-<NUM>, respectively. Each of fluid chambers <NUM> contains one of compliant chambers <NUM>. Compliant chambers <NUM> may each comprise a flexible membrane, pouch, bag or other structure which may change in shape and volume in response to pressure changes within the associated fluid chamber <NUM>-<NUM>, <NUM>-<NUM>.

Fluid chamber <NUM>-<NUM> comprises a fluid port <NUM>-<NUM>, a flow passage <NUM>-<NUM> and a second fluid port <NUM>-<NUM>. Fluid port <NUM>-<NUM>, flow passage <NUM>-<NUM> and fluid port <NUM>-<NUM> are similar to port <NUM>, flow passage <NUM> and port <NUM>, respectively, described above. Valve <NUM>-<NUM> is likewise similar to valve <NUM> described above.

Fluid port <NUM>-<NUM> extends from the interior fluid chamber <NUM>-<NUM>, wherein port <NUM>-<NUM> and port <NUM>-<NUM> makes fluid circulation path <NUM>-<NUM> through fluid chamber <NUM>-<NUM>. In one implementation, port <NUM>-<NUM> and port <NUM>-<NUM> are located at opposite ends or sides of fluid chamber <NUM>-<NUM> to promote circulation across a greater portion of the length or width of fluid chamber <NUM>-<NUM>. In one implementation, fluid port <NUM>-<NUM> is located proximate to the floor of fluid chamber <NUM>-<NUM>, such as proximate to a bottom wall of chamber <NUM>-<NUM> or proximate to the top surface of filter <NUM>-<NUM>. As a result, such circulation is more likely to agitate or remix particles that may have already settled or begun to settle (sometimes referred to as sediment) towards the bottom of fluid chamber <NUM>-<NUM>. In one implementation, port <NUM>-<NUM> is spaced no greater than <NUM> from a top of filter <NUM>-<NUM> or the otherwise formed bottom of fluid chamber <NUM>-<NUM>.

In the example illustrated, fluid port <NUM>-<NUM> also serves as a port for fluid chamber <NUM>-<NUM> of pressure regulator <NUM>-<NUM>. Fluid being circulated into fluid chamber <NUM>-<NUM> through port <NUM>-<NUM> may flow through and across fluid chamber <NUM>-<NUM> before being discharged through port <NUM>-<NUM>. In one implementation, fluid chambers <NUM>-<NUM> and <NUM>-<NUM> are separated by an intervening or intermediate wall <NUM>, wherein ports <NUM>-<NUM> and the port serving as a port for fluid chamber <NUM>-<NUM> are formed by an opening extending through wall <NUM>.

Similar to port <NUM>-<NUM>, the port of fluid chamber <NUM>-<NUM> is formed along a floor of fluid chamber <NUM>-<NUM>. In some implementations, chamber <NUM>-<NUM> has no floor, wherein filter <NUM>-<NUM> forms a floor of chamber <NUM>-<NUM> and wherein flow passage <NUM>-<NUM> is a general open connection between the interior of chamber <NUM>-<NUM> and filter <NUM>-<NUM>.

When apparatus <NUM> is in a fluid ejection mode, fluid may be supplied to fluid chamber <NUM>-<NUM> and <NUM>-<NUM> through ports <NUM>-<NUM> and <NUM>-<NUM>, respectively. Such fluid passes through fluid chamber <NUM>-<NUM>, <NUM>-<NUM>, through filters <NUM>-<NUM>, <NUM>-<NUM> and to fluid ejection devices <NUM>-<NUM>, <NUM>-<NUM> for ejection as indicated by ejection flow paths <NUM>-<NUM> and <NUM>-<NUM>. Flow passage <NUM>-<NUM> forms a fluid ejection path <NUM>-<NUM> (shown in broken lines) along which fluid flows out of pressure regulator <NUM>-<NUM>, through filter <NUM>-<NUM> and through orifice <NUM>-<NUM> of ejection device <NUM>-<NUM>.

In the above example, fluid circulation paths <NUM>-<NUM> and <NUM>-<NUM> collectively span two fluid chamber <NUM>-<NUM>, <NUM>-<NUM> of two different pressure regulators <NUM>-<NUM>, <NUM>-<NUM>. In such an implementation, fluid may be supplied into fluid chamber <NUM>-<NUM> and pulled from fluid chamber <NUM>-<NUM> to provide such an elongated circulation path to reduce particle sediment. In other implementations, pressure regulators <NUM>-<NUM> and <NUM>-<NUM> may be spaced from one another and connected by an elongate fluid passage. In other implementations, apparatus <NUM> may include more than two pressure regulators, wherein a fluid circulation path may be formed so as to extend through and across each of the more than two pressure regulators. For example, apparatus <NUM> may include three or more pressure regulators arranged in series, wherein fluid supplied to the first pressure regulator the series and withdrawn from the last pressure regulator of the series, passing through the an intermediate pressure regulator or multiple intermediate pressure regulators sandwiched between the first and last pressure regulators of the series.

<FIG> is a flow diagram of an example fluid circulation method <NUM>. Method <NUM> circulates fluid within and across the fluid chambers of two pressure regulator to further mix particles suspended within the fluid to reduce settling of the particles, increasing the robustness of apparatus <NUM>. Although method <NUM> is described in the context of being carried out by apparatus <NUM>, it should be appreciated that method <NUM> may likewise be carried out with any of the systems or apparatus disclose hereafter or with similar systems or apparatus.

As indicated by block <NUM>, fluid supplied to fluid chamber <NUM>-<NUM> of pressure regulator <NUM>-<NUM>. In one implementation, the fluid being supplied may comprise a fluid having larger or heavier particles or a higher concentration of particles that may be more prone to settling. For example, in one implementation, the fluid being supplied may comprise a printing fluid, such as an ink, containing heavier pigments or a higher concentration of pigments that may render the ink more susceptible to pigment settling. In one implementation, the printing fluid may comprise a white ink having heavier metallic particles or a higher concentration of metallic particles that provide the white ink with enhanced white color.

As indicated by block <NUM>, a determination is made as to whether apparatus <NUM> is in a circulation mode, a mode in which fluid is circulated through pressure regulators <NUM> without being directed to fluid ejection devices <NUM>. As indicated by block <NUM>, in response to a controller determining that apparatus <NUM> is not in the circulation mode, fluid is directed from the fluid chamber <NUM>-<NUM> and through the underlying filter <NUM>-<NUM> to the fluid ejection device when <NUM><NUM>. In some implementations, fluid may be additionally supplied through port <NUM>-<NUM> into fluid chamber <NUM>-<NUM>, through filter <NUM>-<NUM> and to fluid ejection device <NUM>-<NUM> for ejection.

As indicated by block <NUM>, in response to apparatus <NUM> being in the circulation mode, fluid within fluid chamber <NUM>-<NUM> is circulated through and out of fluid chamber <NUM>-<NUM>, through port <NUM>-<NUM>, away from the underlying filter <NUM>-<NUM>. As indicated by block <NUM>, the fluid is then circulated from the fluid chamber <NUM>-<NUM> into fluid chamber <NUM>-<NUM> of the second pressure regulator <NUM>-<NUM>. As indicated by block <NUM>, the fluid is finally circulated through and out of the second fluid chamber <NUM>-<NUM> through port <NUM>-<NUM>. In one implementation, the fluid is pulled through port <NUM>-<NUM>. In one implementation, an actuator is used to actuate valve <NUM>-<NUM> to open port <NUM>-<NUM>. In one implementation, the actuator may comprise a pump or inflator that inflates compliant member <NUM>-<NUM> to change its inflation level and thereby cause valve <NUM>-<NUM> to open port <NUM>-<NUM> for the circulation of fluid out of fluid chamber <NUM>-<NUM>. The fluid circulated out of chamber <NUM>-<NUM> may be circulated back to the apparatus <NUM> for ejection through either port <NUM>-<NUM> or <NUM>-<NUM>.

<FIG> and <FIG> are sectional views illustrating portions of an example fluid ejection and circulation apparatus <NUM>. Apparatus <NUM> may be in the form of a print or fluid ejection module which may be a removable and replaceable component of a larger overall fluid ejection system. Apparatus <NUM> comprises fluid ejection die <NUM>, providing an array of fluid ejection devices <NUM>, die carrier <NUM>, standpipes <NUM>-<NUM>, <NUM>-<NUM> (collectively referred to as standpipes <NUM>), filter chambers <NUM>-<NUM>, <NUM>-<NUM> (collectively referred to as filter chambers <NUM>), filters <NUM>-<NUM>, <NUM>-<NUM> (collectively referred to as filters <NUM>), fluid needles <NUM>-<NUM>, <NUM>-<NUM> (collectively referred to as fluid needles <NUM>) and pressure regulators <NUM>-<NUM>, <NUM>-<NUM> (collectively referred to as pressure regulators <NUM>).

<FIG> is a sectional view illustrating fluid ejection die <NUM>, die carrier <NUM> and standpipes <NUM> in greater detail. Fluid ejection die <NUM> comprises a fluid ejection die supporting a series or array of fluid ejection devices <NUM>. Each of fluid ejection device <NUM> may be similar to fluid ejection device <NUM> described above. In the example illustrated, fluid ejection die <NUM> comprises a pair of slots or a series of fluid feed holes <NUM>-<NUM>, <NUM>-<NUM> through which fluid is supplied to the individual fluid ejection devices <NUM>.

Die carrier <NUM> is bonded to die <NUM> and supports die <NUM> below standpipes <NUM>-<NUM> and <NUM>-<NUM>. In one implementation, the material forming standpipes <NUM> as a first coefficient of thermal expansion, the material forming die <NUM> has a second coefficient of thermal expansion and the material forming die carrier <NUM> has a third coefficient of thermal expansion between that of die <NUM> and the material standpipes <NUM>. In one implementation, die <NUM> is formed from silicon whereas the material standpipes <NUM> is formed from a polymer in the material die carrier <NUM> is formed from a ceramic. As shown by <FIG>, die carrier <NUM> includes slots <NUM>-<NUM> and <NUM>-<NUM> which supply fluid from standpipes <NUM>-<NUM> and <NUM>-<NUM> to fluid feed holes <NUM>-<NUM> and <NUM>-<NUM>, respectively.

Standpipes <NUM> extend side-by-side parallel to one another above die carrier <NUM> and above ejection die <NUM>. Standpipes <NUM> receive fluid from filter chambers <NUM>-<NUM>, <NUM>-<NUM>, respectively, after the fluid has passed through filters <NUM>-<NUM> and <NUM>-<NUM>, respectively (shown in <FIG> and <FIG>). In particular, standpipe <NUM>-<NUM> receives fluid from filter chamber <NUM>-<NUM> through a fluid conduit <NUM>-<NUM> as seen in <FIG>. Standpipe <NUM>-<NUM> receives fluid from filter chamber <NUM>-<NUM> through a fluid conduit <NUM>-<NUM> as seen in <FIG>.

Filters <NUM> are similar to filters <NUM> described above. Filter <NUM>-<NUM> filters the fluid supplied from pressure regular <NUM>-<NUM> to filter chamber <NUM>-<NUM> and ultimately to fluid feed holes <NUM>-<NUM> shown in <FIG>. Filter <NUM>-<NUM> filters fluid supplied from pressure regulator <NUM>-<NUM> to filter chamber <NUM>-<NUM> and ultimately to fluid feed holes <NUM>-<NUM> as shown in <FIG>. In the example illustrated, filters <NUM>-<NUM> and <NUM>-<NUM> form the floor of the respective fluid chambers of pressure regulator <NUM>-<NUM> and <NUM>-<NUM>.

Pressure regulators <NUM>-<NUM> and <NUM>-<NUM> are substantially identical to one another. Pressure regulators <NUM>-<NUM>, <NUM>-<NUM> comprises fluid chambers <NUM>-<NUM>, <NUM>-<NUM>, compliant chambers <NUM>-<NUM>, <NUM>-<NUM>, valve <NUM>-<NUM>, <NUM>-<NUM>. Fluid chambers <NUM>-<NUM>, <NUM>-<NUM> contain compliant chambers <NUM>-<NUM>, <NUM>-<NUM>, respectively. Fluid chambers <NUM>-<NUM>, <NUM>-<NUM> comprises ports <NUM>-<NUM>, <NUM>-<NUM>, respectively, through which fluid may flow into and out of the respective fluid chambers <NUM>.

In the example illustrated, fluid chambers <NUM>-<NUM> and <NUM>-<NUM> are connected to one another by connecting port <NUM>. Port <NUM> extends through an intervening wall <NUM> separating fluid chambers <NUM>. Port <NUM> facilitates the circulation of fluid from the interior of fluid chamber <NUM>-<NUM> into the interior of fluid chamber <NUM>-<NUM> when apparatus <NUM> is in a circulation mode. As a result, port <NUM> facilitates a circulation mode in which fluid may be circulated through fluid chamber <NUM>-<NUM> of pressure regulator <NUM>-<NUM> to agitate or mix suspended particles or pigments without the fluid having to flow through filter <NUM>-<NUM> for such circulation. Port <NUM> further facilitates circulation of fluid through fluid chamber <NUM>-<NUM> to and out of port <NUM>-<NUM> to agitate or mix suspended particles or pigments without the fluid having to flow through filter <NUM>-<NUM> for such circulation.

According to the invention, port <NUM> is positioned proximate to each of filters <NUM> to provide a greater degree of fluid flow adjacent to and along the filters <NUM>. As a result, the higher concentration of particle sediment collecting near filters <NUM> may be stirred or mixed and resuspended. In one implementation, port <NUM> has a mouth having a lower edge space no greater than <NUM> above the top surface of filters <NUM>. In one implementation, the lower edge of port <NUM> is flush with the top surface of filters <NUM>.

Compliant chambers <NUM> each comprise a flexible membrane, pouch, bag or other structure which may change in shape and volume in response to pressure changes within the respective fluid chambers <NUM>. In one implementation, each of compliant chambers <NUM> may comprise a flexible bag having an interior connected to atmosphere by an atmospheric port <NUM> (shown in <FIG>).

Valves <NUM> each comprise valve mechanism that selectively opens and closes its respective ports <NUM>-<NUM>, <NUM>-<NUM> (portions of which are shown in broken lines due the shown section) in response to or based upon the inflation level, shape or size of the associated compliant chamber <NUM> which is itself dependent upon the fluid pressure level within interior of the associated fluid chamber <NUM>. As shown by <FIG> and <FIG>, each of ports <NUM> passes through a crown <NUM> against which a valve seat <NUM> may bear against to seal the respective port <NUM>. In the example illustrated, the valve seat <NUM> of each of pressure regulators <NUM> pivots between port closing or sealing position and a port opening position by use of a lever that engages compliant chamber <NUM>. In one implementation, the valve seat <NUM> is formed from a resilient a rubber -like material. Examples of such materials include silicon rubbers, fluoro silicate elastomers, or blends thereof.

<FIG> illustrate portions of pressure regulator <NUM>-<NUM> in more detail. As noted above, pressure regular <NUM>-<NUM> is substantially similar to pressure regulator <NUM>-<NUM>. As shown by <FIG>, compliant chamber <NUM>-<NUM> may be in the form of an inflatable bag captured between a pair of levers <NUM>, <NUM>. Levers <NUM>, <NUM> are resiliently biased towards one another and against compliant chamber <NUM>-<NUM> by a tension spring <NUM> (shown in <FIG>). As shown by <FIG>, lever <NUM> further supports valve seat <NUM>. Lever <NUM> pivots about axles <NUM> which are pivotally received within the body of apparatus <NUM> is shown by <FIG> and <FIG>. Depending upon the inflation level of compliant chamber <NUM>-<NUM>, valve seat <NUM> may be pivoted into sealing engagement with crown <NUM> or out of sealing engagement with respect to crown <NUM>.

<FIG> illustrates fluid ejection and circulation apparatus <NUM> provided as part of a larger fluid ejection and circulation system <NUM>. In addition to apparatus <NUM>, system <NUM> comprises external fluid source <NUM>, fluid pumps <NUM>-<NUM>, <NUM>-<NUM> (collectively referred to as fluid pumps <NUM>), pumps/inflators <NUM>-<NUM>, <NUM>-<NUM> (collectively referred to as pumps/inflators <NUM>) and controller <NUM>. External fluid source <NUM>'s serves as a reservoir containing fluid to be supplied to each of pressure regulators <NUM> and ultimately to fluid ejection die <NUM>. Pumps <NUM> selectively pump fluid from fluid source <NUM> to fluid chambers <NUM>-<NUM>, <NUM>-<NUM> or pull fluid from fluid chambers <NUM>-<NUM>, <NUM>-<NUM>, respectively, back into fluid source <NUM>. Pumps/inflators <NUM> are selectively connectable to their respective compliant chambers <NUM>-<NUM> and <NUM>-<NUM>. Pump/inflators <NUM> close off the interior of their respective compliant chambers from atmosphere and controllably inflate their respective compliant chambers <NUM> to open the respective valves <NUM>-<NUM> and <NUM>-<NUM>. In some implementations, when the apparatus is in the circulation mode, a rubber or elastomeric boot having an inflation port connected to an inflator is moved over and seals an atmospheric port of the compliant chamber that is to be inflated to open the valve.

Controller <NUM> actuates system <NUM> and apparatus <NUM> between the fluid ejection mode or state in a fluid circulation mode or state. Controller <NUM> may comprise a processing unit <NUM> that follows instructions contained in a non-transitory computer-readable medium <NUM>. Following instructions contained in memory <NUM>, processing unit <NUM> may output control signals to control the operation of pumps <NUM> and pump/inflators <NUM> to actuate apparatus <NUM> between the fluid ejection mode and the fluid circulation mode.

In the fluid ejection mode, each of the pressure regulators <NUM> maintains fluid backpressure in the fluid ejection die <NUM> within a narrow range below atmospheric levels in order to avoid depriming of the nozzles are ejection orifices (leading to drooling or fluid leaking) while optimizing fluid ejection device pressure conditions for fluid ejection or printing. During non-operational periods, this pressure is maintained statically by surface tension of fluid in the ejection orifices. The pressure regulators <NUM> operate by using spring <NUM> to apply a force to an area of their respective compliant chambers <NUM> which are open to the atmosphere through atmospheric ports <NUM>, thereby establishing a negative internal pressure for fluid containment in the apparatus. Lever <NUM> pivots in response to inflation or deflation of the associated compliant chamber <NUM> to seat or unseat valve seat <NUM> with respect to the associated crown <NUM> to seal or open the respective port <NUM>.

During ejection of fluid, fluid is expelled by fluid ejection die <NUM> which evacuates fluid from the pressure-controlled fluid containment system of the regulators <NUM>. When the pressure in the respective regulator <NUM> reaches the backpressure set point established through design choices for spring force (i.e., spring constants K) and flexible film area, the valve seat <NUM> opens and allows fluid to be delivered from pump <NUM>-<NUM>, <NUM>-<NUM> connected to the port <NUM>-<NUM> and port <NUM>-<NUM>, respectively. The regulators <NUM> each operate from fully open to fully closed (i.e., seated) positions. Positions in between the fully open and fully closed positions modulate the pressure drop through the regulator valve itself, causing the valve mechanism <NUM> to act as a flow control element.

In the circulation mode, fluid is not ejected from apparatus <NUM>. <FIG> illustrates apparatus <NUM> in a fluid circulation mode in which fluid is supplied into fluid chamber <NUM>-<NUM>, passes through port <NUM>, circulates through fluid chamber <NUM> and is discharged or pulled from fluid chamber <NUM>-<NUM>. In such a circulation mode, controller <NUM> causes pump <NUM>-<NUM> to supply fluid from fluid source <NUM> through internal flow passages and through port <NUM>-<NUM> into fluid chamber <NUM>-<NUM> as indicated by arrows <NUM>. Controller <NUM> causes pump/inflators <NUM>-<NUM> to disconnect port <NUM> of compliant chamber <NUM>-<NUM> from atmosphere and to alternatively inflate compliant chamber <NUM>-<NUM> through port <NUM> two point such that valve seat <NUM> is pivoted out of sealing engagement with crown <NUM> about port <NUM>-<NUM>, opening port <NUM>-<NUM>. Controller <NUM> further output control signals causing pump <NUM>-<NUM> to apply a vacuum pressure to pull or draw fluid from fluid chamber <NUM>-<NUM> through the opened port <NUM>-<NUM> and back into fluid source <NUM> as indicated by arrows <NUM>. As a result, a complete circulation path is formed wherein fluid from fluid source <NUM> is supplied to fluid chamber <NUM>-<NUM> which flows through port <NUM> (as indicated by arrow <NUM>) into fluid chamber <NUM>-<NUM>. Fluid within fluid chamber <NUM>-<NUM> is drawn or pulled through port <NUM>-<NUM>, returning to fluid source <NUM>. Such circulation bypasses filters <NUM>-<NUM> and <NUM>-<NUM>.

In the example illustrated, system <NUM> may provide such circulation in a reverse direction compared to that shown in <FIG>. To provide such a reverse circulation flow, controller <NUM> causes pump <NUM>-<NUM> to supply fluid from fluid source <NUM> through internal flow passages and through port <NUM>-<NUM> into fluid chamber <NUM>-<NUM> as indicated by arrows <NUM>. Controller <NUM> causes pump/inflators <NUM>-<NUM> to disconnect port <NUM> of compliant chamber <NUM>-<NUM> from atmosphere and to alternatively inflate compliant chamber <NUM>-<NUM> through port <NUM> to an extent such that valve seat <NUM> is pivoted out of sealing engagement with crown <NUM> about port <NUM>-<NUM>, opening port <NUM>-<NUM>. Controller <NUM> further outputs control signals causing pump <NUM>-<NUM> to apply a vacuum pressure to pull or draw fluid from fluid chamber <NUM>-<NUM> through the opened port <NUM>-<NUM> and back into fluid source <NUM>, opposite to the direction indicated by arrows <NUM>. As a result, a complete circulation path is formed wherein fluid from fluid source <NUM> is supplied to fluid chamber <NUM>-<NUM> which flows through port <NUM> (opposite to the direction indicated by arrow <NUM> into fluid chamber <NUM>-<NUM>. Fluid within fluid chamber <NUM>-<NUM> is drawn or pulled through port <NUM>-<NUM>, returning to fluid source <NUM>. Such circulation bypasses filters <NUM>-<NUM> and <NUM>-<NUM>.

Claim 1:
A fluid ejection and circulation apparatus (<NUM>, <NUM>) comprising:
a fluid ejection device (<NUM>, <NUM>);
a filter (<NUM>, <NUM>) to filter fluid to be supplied to the fluid ejection device; and
a pressure regulator (<NUM>, <NUM>) comprising:
a fluid chamber (<NUM>, <NUM>) comprising:
a first port (<NUM>, <NUM>) for connection to a fluid source (<NUM>);
a flow passage (<NUM>) connected to the filter;
a compliant chamber (<NUM>, <NUM>) within the fluid chamber that is to undergo different inflation levels in response to fluid chamber pressure; and
a valve (<NUM>, <NUM>) to open and close the first port in response to changes in an inflation level of the compliant chamber,
wherein the fluid chamber comprises a second port (<NUM>, <NUM>) cooperating with the first port to form a circulation path through the fluid chamber that is directed away from the filter,
characterized in that the second port is positioned proximate to the filter to provide a fluid flow adjacent to and along the filter.