Filter for ink

Abstract

A filter module for filtering ink includes a filter housing defining a filter chamber, an inlet port, a first outlet port, and a second outlet port. The filter module further includes a first filter element including a first filter media disposed in the filter chamber. The filter housing is configured to define a first filtrate path from the inlet port through the first filter element to the first outlet port and a second path from the first inlet port across an outer surface of the first filter element to the second outlet port. In use, the first outlet port and the second outlet port are positioned vertically above the inlet port.

Description

[Technical Field]

[0001] This invention relates to inkjet printing, and more particularly to an ink filter for filtering ink, which may be for use with pigmented inks in an inkjet printer, such as a continuous inkjet printer. [Background technology]

[0002] In inkjet printing systems, print consists of individual droplets of ink that are generated at a nozzle and propelled towards a substrate. There are two main systems: drop-on-demand, where ink droplets for printing are generated as they are needed, and continuous inkjet printing, where droplets are generated continuously, only selected ones are directed towards the substrate, and others are recirculated back into the ink supply.

[0003] A continuous inkjet printer supplies pressurized ink to a printhead drop generator, where a continuous jet or stream of ink emanating from a nozzle is energized, for example, by a vibrating piezoelectric element, to form individual, regular droplets. The droplets are directed past charging electrodes, which selectively and separately impart predetermined charges to them before passing through a transverse electric field, which may be provided across a pair of deflection plates. Each charged droplet is deflected by the electric field by an amount dependent on its charge magnitude before impacting the substrate; uncharged droplets proceed without deflection and are collected in a gutter, from which they are recycled to the ink supply for reuse. Charged droplets bypass the gutter and strike the substrate at a location determined by the charge on the droplet and the position of the substrate relative to the printhead. Typically, the substrate is moved in one direction relative to the printhead and the droplets are deflected in a direction approximately perpendicular to that, although the deflector plates may be oriented at an angle to the perpendicular to compensate for the velocity of the substrate (movement of the substrate relative to the printhead between arriving droplets means that the line of droplets may not otherwise extend perfectly perpendicular to the direction of substrate movement).

[0004] In continuous inkjet printing, characters can be printed from a matrix containing a regular array of potential drop positions. Each matrix contains multiple columns (strokes), each defined by a line containing multiple potential drop positions (e.g., seven) determined by the charge applied to the drop and various other influencing factors. That is, each available drop is charged according to its intended position within the stroke. If a particular drop is to be unused, it is uncharged and captured in a gutter for recirculation. This cycle is repeated for all strokes in the matrix and then begins again for the next character matrix.

[0005] Ink is delivered under pressure to the printhead by an ink supply system typically housed within a sealed cabinet compartment that includes separate compartments for control circuitry and a user interface panel. The system includes a main pump that draws ink from ink storage tanks in the ink supply system through a filter and delivers it under pressure to the printhead. As ink is consumed, the tanks are replenished as needed from replaceable ink cartridges releasably connected to the tanks by supply conduits. Ink is pumped from the tanks to the printhead through flexible delivery conduits. Unused ink droplets captured by a gutter are recirculated by the pump back to the tanks through a return conduit. The flow of ink in each of the conduits is typically controlled by solenoid valves and / or other similar components.

[0006] Reliable droplet generation (due to jet break-up) depends on the ink having substantially non-viscous properties, and therefore the ink in the ink tank is preferably low in concentration. The ink recirculated from the gutter is solvent-depleted due to solvent evaporation. Therefore, the ink (storage) tank continuously adjusts its mixture with make-up solvent from a replaceable solvent cartridge to ensure that the ink being drawn from the ink tank has an acceptable viscosity.

[0007] Various types of inks may be used in continuous inkjet printers. The inks may contain organic solvents selected from C1-C4 alcohols, C4-C8 ethers, C3-C6 ketones, C3-C6 esters, and mixtures thereof. The inks may contain different types of colorants. In some situations, dye-based inks are used. This is typically the case when the substrate on which the printing is to be performed is relatively light in color, so that light reflected from the surface is colored by the dyes contained in the ink, resulting in a visible pattern for the user. On the other hand, pigment inks may be preferred when the surface on which the printing is to be performed is dark in color and therefore does not reflect much light. In such situations, the pigments contained in the ink can reflect certain colors of light, thereby ensuring that the printed image is visible to the user. Of course, both dye-based and pigment inks can be used for printing on some substrates, while pigment inks may be used on light surfaces and dye-based inks may be used on dark surfaces. One particular subgroup of pigment inks is known as hard pigment inks. The pigments in these inks are typically high hardness particulates such as titanium dioxide, which result in a high opacity printed mark.

[0008] When pigmented inks are used, the ink consists of a suspension of colorant (i.e., pigment) particles in a solvent. Various other ingredients or additives (e.g., surfactants or dispersants) may also be included in the ink composition. The ink composition may vary depending on various characteristics such as the desired color, the surface on which printing will be performed, the solvent suitable for the particular application environment, and many other factors.

[0009] The filters within a printer are constantly operating when the printer is in use. Many continuous inkjet printers use venturi pumps that generate suction. Such pumps typically operate with continuous ink flow rates that far exceed the ink flow rate delivered to the printhead. In many cases, the entire ink flow is filtered by a primary filter with a fine (e.g., 10 μm) rating, even though only a small portion of the flow reaches the print nozzles. In such an arrangement, the high volume of filtered ink can lead to filter wear at a higher rate than necessary. Particulates (or pigments, or other debris) can gradually clog the filter. Furthermore, the deposition of pigment particles under the influence of gravity can cause the pigment to accumulate on the filter surface, further contributing to filter performance degradation. Summary of the Invention [Problem to be solved by the invention]

[0010] It is an object of the present invention to provide, inter alia, an improved ink filter for use with ink jet printers (such as continuous ink jet printers) that solves one or more of the problems associated with using pigmented inks such as those mentioned above or other inks that contain sediment and / or solid deposits. [Means for solving the problem]

[0011] According to a first aspect of the present disclosure, there is provided a filter module for filtering ink. The filter module includes a filter housing defining a filter chamber, an inlet port, a first outlet port, and a second outlet port. The filter module includes a first filter element including a first filter media disposed in the filter chamber. The filter housing is configured to define a first filtrate path from the inlet port through the first filter element to the first outlet port and a second path from the first inlet port across an outer surface of the first filter element to the second outlet port, wherein, in use, the first outlet port and the second outlet port are positioned vertically above the inlet port.

[0012] The first filtrate path is sometimes referred to as the "flow-through" path (with respect to the first or main filter media), i.e., the filtrate is flowed through, i.e., filtered by, the first filter media.

[0013] The second path may be referred to as a "cross-flow" path (again, with respect to the first or primary filter media), i.e., the portion of the fluid flowing from the inlet along the second path is forced across the face of the first filter media, but is not necessarily filtered by the first filter media.

[0014] The filter may be for filtering pigmented inks. In particular, the filter may be for hard pigmented inks. The filter may be for use in continuous ink jet printers.

[0015] The first outlet port can be configured to provide fluid communication to the printhead. By positioning the filter to allow ink to pass through a first filter element with a specific absolute rating, it is not necessary to filter all of the ink to the purity required for use with the printhead. Instead, only the volume of ink needed to supply the printhead is filtered to the desired level of filtration. The remaining ink can pass through a filter module to provide a consistent cleaning effect, and can also pass through a filter with a different (e.g., lower) absolute rating (e.g., a coarser filter).

[0016] The provision of an inlet port and first and second outlet ports on the filter module allows for emptying of the filter during shutdown, reducing sediment buildup on the first and / or second filter elements (if present).

[0017] These features can extend the life of the first and second filter elements.

[0018] The filter module is sometimes referred to as a crossflow filter. Advantageously, a higher flow rate of ink can pass through the filter chamber than would occur if only the flow traveling to the printhead were flowing through the filter chamber. This is particularly advantageous because it reduces the likelihood that any sediments in the ink will deposit on the first filter element. The filter housing can have a size dependent on the printer requirements, which varies the desired flow rates (i.e., throughflow and crossflow) along the first filtrate path and the second path.

[0019] The first and second outlet ports are vertically spaced apart from the inlet port and positioned higher on the filter housing when the filter module is installed for use. That is, when the filter module is used in a printer, ink can be pumped in a direction that includes a vertically upward component from the inlet port to the first and second outlet ports. In other words, ink can be pumped through the filter in a direction opposite to the direction of gravity. The flow of ink through each of the first and second filtrate paths can therefore be generally upward. Advantageously, this reduces the likelihood of sediment depositing on the filter.

[0020] The filter module can further include a second filter element including a second filter media disposed in the filter housing, and the second pathway can be a second filtrate pathway from the inlet port through the second filter media to the second outlet port.

[0021] Providing the first and second filter elements in a single filter housing allows for easy replacement of the filters, reducing downtime of the printing system.

[0022] A second filter element can be provided in the filter housing, and the second filter element can be received in a portion of the filter housing that defines at least a portion of the second outlet port.

[0023] The first filter element can have a first absolute rating and the second filter element can have a second absolute rating that is different from the first absolute rating.

[0024] The second absolute rating allows ink flowing along the second filtrate path to be filtered at a coarser level than the first filtrate path.

[0025] The filter housing can be configured to define a third filtrate path from the inlet port through the first filter media to the second outlet port.

[0026] The third filtrate path can pass through the first filter element a first time to a central cavity surrounded by the first filter element, and then pass through the first filter element a second time to an outer cavity surrounding the first filter element.

[0027] Passing the filtrate through the first filter element a second time to the outer cavity surrounding the first filter element "backwashes" the first filter element. That is, the flow of filtrate in a direction opposite to the first filtrate path reduces the extent to which filtered particles are retained by the first filter media.

[0028] Backwashing the first filter element is particularly advantageous when filtering pigmented inks, and even more so when filtering hard-pigmented inks. This is because if the ink flow rate through the first filter element is too low, the pigment in the ink may settle (i.e., accumulate) within the first filter element. While pigment settling may occur while the filter is in use (i.e., when ink is actively pumped through the filter), increased settling rates may occur, for example, when the filter is emptied during printing system shutdown or if the printer is shut down without emptying the filter. Pigment settling is undesirable because it clogs the filter element and shortens its lifespan. The third filtrate path, which backwashes the first filter element, reduces pigment settling in the first filter element, thereby helping to extend the lifespan of the first filter element.

[0029] During use, only a relatively low ink flow rate is required along the first filtrate path, and the ink can then be delivered to the printhead. However, a lower flow rate through the first filtrate path increases the likelihood of pigment precipitation within the first filter element. Therefore, another advantage of providing the third filtrate path is that the flow rate through the first filtrate path can be reduced without increasing pigment precipitation. In other words, providing the third filtrate path increases the cross-sectional area of ​​the first filter element, which allows for a desirable low flow rate along the first filtrate path while mitigating undesirable precipitation. Therefore, not only can the desired ink flow rate along the first filtrate path be achieved, but the filter's lifespan can also be extended.

[0030] The third filtrate path may be referred to as the "countercurrent" path (again, with respect to the first or main filter media), i.e., the filtrate has already flowed through the first filter a first time before flowing back through the first filter in a countercurrent direction.

[0031] If a second filter is present, the third filtrate path can pass through the first filter media before the second filter media.

[0032] In use, the filter may be positioned to allow ink to flow in a generally upward direction from the inlet port to the first and second outlet ports.

[0033] Flowing in a generally upward direction includes ink flowing in a direction that includes a vertical component. In other words, the ink flow direction includes a component in a direction opposite to gravity. Thus, ink flow through the main chamber can be generally upward. Advantageously, this reduces the likelihood of sediment depositing in the filter. Flowing ink in an upward direction is advantageous after a shutdown and when emptying the filter during a shutdown. While emptying the filter during a shutdown reduces sediment and pigment deposits, some resin may still accumulate on the pleated material surface of the first filter element, which may clog the filter. When ink is resupplied to the filter, the deposited resin is backwashed into suspension in the ink and does not clog the first filter element.

[0034] The first outlet port and the second outlet port may be vertically separated.

[0035] In use, the second outlet port may be positioned vertically above the first outlet port.

[0036] Providing the second outlet port vertically above the first outlet port includes providing the second outlet port immediately vertically above the first outlet port, and providing the second outlet port in a region of the filter housing that is vertically spaced above the first outlet port, but not necessarily in the same plane. Stated another way, the inlet port, the first outlet port, and the second outlet port may each define a center of gravity, and the vertical distance between the center of gravity of the inlet port and the center of gravity of the second outlet port may be greater than the vertical distance between the center of gravity of the inlet port and the center of gravity of the first outlet port. Thus, in use, more work must be done against gravity to pump ink to the second outlet port compared to pumping ink to the first outlet port.

[0037] In use, locating the second outlet port vertically above the first outlet port is advantageous because it allows air within the chamber to exit the filter housing through the second outlet port instead of through the first outlet port, which may be connected to the printhead, so that any air bubbles that may become trapped in the filter housing can be easily removed without passing to the print nozzles.

[0038] It is believed that locating the second outlet port vertically above the first outlet port is further advantageous as it causes ink flowing to the second outlet port to flow around or through the first filter element, increasing the effective flow rate experienced by the first filter element and thereby reducing the settling rate.

[0039] In use, the flow of ink along the first filtrate path may be in a direction generally opposite to the direction in which gravity acts.

[0040] In use, the flow of ink along the second path may be in a direction generally opposite to the direction in which gravity acts.

[0041] The second passageway can include a passageway defined between an outer surface of the first filter element and a wall of the filter housing that defines the chamber.

[0042] The second (filtrate) path can surround the outermost surface of the first filter element. By surrounding the outermost surface, we mean that the second filtrate path can, for example, surround the sidewall of the first filter element and is not limited to surrounding all sides of the first filter element. That is, ink flowing to the second outlet port can pass across the outermost surface of the first filter element. The outermost surface can be, for example, the sidewall of the filter element. This allows for a lower flow rate of ink through the first filter element compared to the flow rate of ink through the second filter element, which is desirable for delivering ink to the print nozzles through the first outlet port, while maintaining a flow rate of ink along the second flow path high enough to mitigate deposition of sediment and ink pigments within the filter.

[0043] The first filter element can include a first end and an opposing second end, and the first and second ends can include first and second closures, respectively.

[0044] Such an arrangement promotes ink flow across an exterior surface area of ​​the first filter element. The first filter element can define a sidewall extending between first and second ends.

[0045] The first filter element may include an outlet port engaging arrangement for facilitating the flow of ink to the first outlet port.

[0046] The absolute rating of the second filter media may be greater than the absolute rating of the first filter element.

[0047] The effective surface area of ​​the first filter element may be greater than the effective surface area of ​​the second filter element.

[0048] The term effective surface area encompasses the total area of ​​the filter media that is exposed to fluid flow and available for filtration. Such effective surface area may be significantly greater than the geometric area of ​​the filter media when a depth filter is used (e.g., foam, multi-layer filter, or random fiber filter).

[0049] The first filter media may be a pleated filter media.

[0050] The first filter element can include a pleated protective filter that at least partially covers the pleated filter media.

[0051] The pleated filter media can be made of polypropylene. The pleated protection filter can be made of a material, such as stainless steel, that is highly resistant to chemical attack by ink. The pleated protection filter can surround the outer surface of the pleated filter media. The presence of the pleated protection filter prevents deterioration of the pleated media. In particular, the pleated filter media may deteriorate over time, and portions of the pleated filter media may become loose from the majority of the first filter media. The pleated protection filter can prevent any loose portions of the pleated filter media from mixing with ink in the main chamber and / or being carried away from the first filter element.

[0052] The first filter element can include an injection screen disposed between the pleated filter media and the first injection port.

[0053] The exit screen can prevent portions of the pleated filter material from passing to the first exit port. The exit screen can include a stainless steel mesh.

[0054] The absolute rating of the first filter element can be determined by the exit screen.

[0055] The first filter element can define a central cavity, and the first filter element can include a central support structure positionable within the central cavity.

[0056] The nominal rating of the first filter element may be determined by the pleated filter media.

[0057] That is, the nominal performance of the first filter element may be determined primarily by the pleated filter media, rather than any pleated protective filter or other support structure.

[0058] Alternatively or additionally, the absolute rating of the first filter element may be determined by the pleated filter media.

[0059] The second filter medium can include a mesh filter. The second filter medium can be formed from stainless steel or another suitable material. The nominal and / or absolute rating of the second filter medium can be determined by the mesh filter.

[0060] The first filter media can include a stainless steel mesh filter media.

[0061] In particular, the stainless steel mesh filter media may be a stainless steel depth filter.Advantageously, the number of components in the first filter element is minimized.

[0062] The first filter media may include a polypropylene mesh or a PTFE mesh.

[0063] The inlet port can be configured to be connected to an ink pump for pumping ink along at least the first, second, and third filtrate paths.

[0064] The pump can be arranged to induce a higher ink flow rate through the filter upon start-up, which promotes remixing of any sediment or resin that may have deposited in the filter, particularly on or on the first and / or second filter elements, thereby reducing clogging of the first and second filter elements.

[0065] The first filter element may be generally cylindrical.

[0066] By providing the first filter element with a cylindrical profile, the surface area over which ink passes is increased. Advantageously, the overall flow rate of ink through the filter can be maintained at a rate greater than a predetermined minimum rate, thereby reducing the likelihood of sediment buildup within the first filter element while allowing a desired flow rate of ink to pass from the inlet port to the first outlet port.

[0067] The filter module may have a round shape (generally cylindrical with rounded ends).

[0068] The first outlet port and the second outlet port may be located on a single face of the filter housing.

[0069] By providing all three fluid ports on a single surface, the filter module can be installed and removed in a simple operation.

[0070] In use, the flow rate of ink through the second outlet port may be greater than the flow rate of ink through the first outlet port.

[0071] The relative flow rate can be defined as the ink flow rate during a printing operation, but not during a cleaning or maintenance operation. During printer operation, the ink flow rate through the second outlet port can be at least twice the ink flow rate through the first outlet port.

[0072] The filter module may further include a presence detection feature configured to interact with a detector configured to detect when the filter is engaged with the printing system.

[0073] Suitable presence detection mechanisms or detectors can include, for example, Hall Effect sensors. Presence detection features can include magnets. In particular, magnets for use with Hall Effect sensors can be provided on the filter housing. Other suitable presence detection mechanisms and motion sensors can be provided. The presence detection mechanism can be used to control the operation of the pump and, therefore, the flow of ink into the inlet port.

[0074] The filter module may further include a removal handle.

[0075] The removal handle can allow a user to grip the filter and apply a pulling force to allow easier removal of the filter from the printer.

[0076] The removal handle can include one or more apertures. The removal handle can include two apertures. The apertures provide an opening that allows an operator to grasp and manipulate (e.g., remove) the filter module. Thus, the apertures can assist an operator in installing and removing the filter module.

[0077] The filter module may further include an engagement structure for engagement with a complementary structure on the printer to secure the filter module in an installed configuration.

[0078] Providing an engagement structure, such as a handle-like feature, can allow the filter module to securely engage with the printer. Providing a secure engagement between the filter module and the printer mitigates accidental release or ejection of the filter module when the filter module is placed under pressure caused by, for example, pumping ink therethrough.

[0079] According to a second aspect of the present invention there is provided a filter module for filtering ink, the filter module comprising: A filter housing, filter chamber, Inlet port, a first outlet port; and a second outlet port, a filter housing defining a first filter element including a first filter media disposed in the filter chamber; Including, the filter housing is configured to define a first filtrate pathway from the inlet port through the first filter element to the first outlet port and a second pathway from the first inlet port across an exterior surface of the first filter element to the second outlet port; the inlet port, the first outlet port, and the second outlet port are located on a single face of the filter housing; In use, the first and second outlet ports are positioned vertically above the inlet port.

[0080] Optional features of the first aspect of the invention may be combined with the second aspect of the invention, except where they are already present in the second aspect.

[0081] According to a third aspect of the present invention there is provided a filter module for filtering ink, the filter module comprising: A filter housing, filter chamber, Inlet port, a first outlet port; and a second outlet port, a filter housing defining a first filter element including a first filter medium disposed in the filter chamber and a second filter element including a second filter medium disposed in the filter housing; Including, the filter housing is configured to define a first filtrate pathway from the inlet port through the first filter element to the first outlet port and a second pathway from the first inlet port across an exterior surface of the first filter element to the second outlet port; the second path is a second filtrate path from the inlet port through the second filter media to the second outlet port; In use, the first and second outlet ports are positioned vertically above the inlet port.

[0082] Optional features of the first aspect of the invention may be combined with the third aspect of the invention, except where they are already present in the third aspect. Features of the third aspect may be combined with the first and / or second aspect of the invention.

[0083] According to a fourth aspect of the present invention there is provided a filter module for filtering ink, the filter module comprising: A filter housing, filter chamber, Inlet port, a first outlet port; and a second outlet port, a filter housing defining a first filter element disposed in the filter chamber, the first filter element including a first pleated filter media and further including an injection screen disposed between the pleated filter media and the first injection port; Including, the filter housing is configured to define a first filtrate pathway from the inlet port through the first filter element to the first outlet port and a second pathway from the first inlet port across an exterior surface of the first filter element to the second outlet port; In use, the first and second outlet ports are positioned vertically above the inlet port.

[0084] Optional features of the first aspect of the invention may be combined with the fourth aspect of the invention, except where they are already present in the fourth aspect. Features of the fourth aspect may be combined with the first, second and / or third aspects of the invention.

[0085] According to a fifth aspect of the present invention there is provided a filter module for filtering ink, the filter module comprising: A filter housing, filter chamber, Inlet port, a first outlet port; and a second outlet port, a filter housing defining a first generally cylindrical filter element including a first filter medium disposed in the filter chamber; Including, the filter housing is configured to define a first filtrate pathway from the inlet port through the first filter element to the first outlet port and a second pathway from the first inlet port across an exterior surface of the first filter element to the second outlet port; In use, the first and second outlet ports are positioned vertically above the inlet port.

[0086] Optional features of the first aspect of the invention may be combined with the fifth aspect of the invention, except where they are already present in the fifth aspect. Features of the fifth aspect may be combined with the first, second, third and / or fourth aspects of the invention.

[0087] The inlet port, first outlet port, and second outlet port of the third, fourth, or fifth aspects may be located on a single face of the filter housing.

[0088] The filter module of the second, fourth, or fifth aspect can further include a second filter element including a second filter media disposed in the filter housing, and the second pathway can be a second filtrate pathway from the inlet port through the second filter media to the second outlet port.

[0089] The first filter media of the second, third, or fifth aspects can be pleated filter media, and the first filter element can include an injection screen disposed between the pleated filter media and the first injection port.

[0090] The first filter element of the second, third or fourth aspects may be generally cylindrical.

[0091] According to a sixth aspect disclosed herein, there is provided a continuous ink jet printer including an ink circuit comprising an ink tank, an ink pump arrangement and a filter module for filtering ink according to the first, second, third, fourth or fifth aspect of the present invention, the ink pump being configured to pump ink from the ink tank through a first inlet port and passing along at least one of a first filtrate path and a second path.

[0092] In use, the filter module can be positioned to pump ink in a generally upward direction away from the inlet port.

[0093] That is, the filter is oriented in the printer so that the pump pumps ink through the filter in a direction that has a component opposite to the direction in which gravity acts.

[0094] The continuous ink jet printer may further include a pressure sensor that may be configured to sense a pressure drop across the first filter element.

[0095] The continuous ink jet printer may further include a pressure sensor that may be configured to sense a pressure drop across the second filter element.

[0096] Sensing the pressure drop across the first and / or second filter elements can be used to determine when the first and / or second filter elements need to be replaced. The pressure change across the first and / or second filter elements can be compared to known or tested pressure drops to determine when the first and / or second filter elements need to be replaced or cleaned. The pressure drop can be measured during printer startup or shutdown. When the pressure drop reaches a predetermined value, it can indicate that the first and / or second filter elements need replacement. The pressure sensor can be coupled to a controller, which adjusts the ink pump flow rate depending on the pressure.

[0097] According to a seventh aspect of the present disclosure, there is provided a filter housing for a filter module for filtering ink. The filter housing defines a filter chamber, an inlet port, a first outlet port, and a second outlet port. The filter chamber is configured to receive a first filter element, and the filter housing is configured to define a first filtrate pathway from the inlet port through the received first filter element to the first outlet port and a second pathway from the first inlet port across an outer surface of the received first filter element to the second outlet port, wherein, in use, the first outlet port and the second outlet port are disposed vertically above the inlet port.

[0098] The filter housing can be configured to receive a second filter element.

[0099] The second outlet port can be configured to receive at least a portion of a second filter element.

[0100] The filter housing may be formed from at least two parts.

[0101] The two parts of the filter housing may be joined by spin welding.

[0102] The first and second outlet ports can be vertically spaced apart from the inlet port when the filter is installed in the printer. The second outlet port can be vertically spaced apart from the first outlet port when the filter is installed in the printer. The inlet port, the first outlet port, and the second outlet port can be located on a single face of the filter housing.

[0103] According to an eighth aspect disclosed herein, there is provided a method of manufacturing a filter module for filtering ink according to the first, second, third, fourth or fifth aspects of the present invention, the method comprising: disposing a second filter element including a second filter media having a second absolute rating within a second outlet port further defined by a filter housing defining an inlet port, a first outlet port and a filter chamber; and disposing a first filter element including a first filter media having a first absolute rating within the filter chamber.

[0104] The first absolute rating may be different from the second absolute rating.

[0105] The method can further include forming a first filter element, which includes forming a pleated filter media having a central cavity, securing a first closure over a first end of the filter media, and securing a second closure over a second end of the filter media opposite the first end.

[0106] Prior to securing the first and second closures, the method may include positioning a central support structure within the central cavity and surrounding an outer surface of the pleated filter media with a pleated protective filter.

[0107] The method may further include heat welding the first closure and the second closure to the pleated filter media.

[0108] The first filter element can include an outlet port engagement arrangement, and placing the first filter element in the main chamber can include engaging the engagement arrangement with the first outlet port.

[0109] The method may further include joining the two parts of the filter housing by spin welding after placing the first filter element in the filter chamber.

[0110] The method can include pumping ink through an inlet port into a filter chamber defined by a filter housing; filtering a first portion of the ink flowing along a first filtrate path with a first filter element disposed in the filter chamber, wherein the filtrate flows from the filter chamber through a first outlet port; and flowing a second portion of the ink along a second path passing across an outer surface of the first filter element to a second outlet port, wherein the flow direction of the ink when flowing along the first filtrate path and the second path can include a component in a direction opposite to gravity.

[0111] The method may further include filtering a second portion of the ink through a second filter.

[0112] Flowing the second portion of the ink along the second path can include filtering through a second filter disposed at the second outlet port.

[0113] Filtering with the first filter element can include filtering a first portion of the ink to remove particles larger than a first predetermined size, and filtering with the second filter element can include filtering a second portion of the ink to remove particles larger than a second predetermined size, which can be larger than the first predetermined size.

[0114] That is, the second filter may have a higher nominal and / or absolute rating than the first filter element.

[0115] According to a ninth aspect disclosed herein, there is provided a method of operating a continuous ink jet printer comprising the method of filtering ink according to the eighth aspect of the invention, the method further comprising pumping a first portion of the ink from a first outlet port to a printhead of the continuous ink jet printer.

[0116] The method may further include pumping a second portion of the ink from a second outlet port to the venturi pump.

[0117] The method may further include pumping a second portion of the ink from a second outlet port to an ink tank of the continuous ink jet printer.

[0118] According to a tenth aspect disclosed herein, there is provided a filter module retention mechanism for retaining a filter module for a continuous ink jet printer, the filter module including a first support and a second support pivotally connected to the first support. The filter module is receivable by at least one of the first and second supports in an unlocked configuration in which the second support is spaced apart from the first support. At least one of the first and second supports includes a first retention feature configured to retain the filter module in a locked configuration in which the second support is proximate to the first support to retain the filter module, and at least one of the first and second supports includes a second retention feature configured to latch the retention mechanism in the locked configuration and prevent rotation of the second support relative to the first support.

[0119] Advantageously, the filter module retention mechanism securely holds the filter module by the first retention feature during activation, but the filter module can be easily released by the operator by the second retention feature for access thereto. Thus, undesired release of the filter module from the retention mechanism during use can be avoided without requiring significant operator intervention to remove the filter module.

[0120] The first support can be described as a fixed support. The second support can be described as a movable or rotatable support. The second support can be directly pivotally connected to the first support, or there can be one or more other intervening components such that the second support is indirectly connected to the first support.

[0121] The filter module may be receivable by at least one of the first and second supports by engagement of a port on the filter module with a corresponding port on the first or second support, and one or both of the first and second supports may abut or engage the filter module to receive the filter module. The filter module is preferably receivable by the second support.

[0122] The first retention feature may be described as a generally axial retention feature, so long as it substantially prevents outward ejection of the filter module upon activation. The first retention feature may be described as a detent or buffer. The first retention feature may actively engage (i.e., abut) the filter module when it is in the locked configuration. The first retention feature may not actively engage (i.e., abut) the filter module when it is in the locked configuration. The first retention feature may be engageable with the filter module in the locked configuration. The first retention feature may act to at least counteract a force exerted on the filter module by fluid being pushed through the filter module upon activation. The first retention feature may be described as securing the filter module in a defined position. The first retention feature may take the form of a ledge or other abutment feature. The first retention feature may engage an upper (outer) surface of the filter module. The first retention feature can directly engage the filter module or can indirectly engage the filter module through one or more other intervening components. The first retention feature can be described as limiting displacement of the filter module. The first retention feature can be described as preventing excessive axial movement of the filter module. The second support can be described as being close to the first support when it cannot rotate any closer to the first support.

[0123] The second retention feature can alternatively be described as a rotational latch. The second retention feature can be described as (rotationally) securing the first support and the second support relative to one another. The second retention feature can be described as releasably securing the first support and the second support relative to one another. When in the locked configuration, rotation of the second support relative to the first support can be completely prevented by the second retention feature. The second retention feature can engage the other of the first and second supports. Alternatively or in combination, the second retention feature can be configured to engage the filter module itself.

[0124] The second retaining feature may be a clip.

[0125] The clip can be described as undergoing elastic deformation by flexing due to features it engages in use, regardless of the features it engages with. The clip can engage with the filter module (e.g., a protrusion thereof). Alternatively, the clip can engage with the other of the first and second supports.

[0126] Advantageously, the clip provides a retention feature that can be easily released upon activation. Preferably, the clip provides a retention force in a direction different from the direction to which the filter module is biased upon activation.

[0127] The clip may include a tapered engagement surface.

[0128] The clip can alternatively be described as including a wedge-shaped surface. The tapered engagement surface is preferably narrowest at the (first) outer end and increases in thickness away from the outer end toward the second end. Biasing of the feature along the tapered engagement surface preferably resiliently deforms the clip. Preferably, the clip includes a recess that receives the feature that is retained after it has undergone its most significant deformation. Thus, the clip can be described as a locking feature that will remain in a relaxed position until it is again deformed, rotationally latching the retention mechanism in a locked configuration.

[0129] The second retention feature can latch the filter module retention mechanism in the locked configuration when the retention mechanism transitions from the unlocked configuration to the locked configuration.

[0130] Advantageously, the second retention feature latches the filter module retention mechanism in the locked configuration when the retention mechanism transitions from the unlocked configuration to the locked configuration, meaning that no manual intervention is required to provide this latching. In other words, latching can be achieved solely by (e.g., automatic) movement of the first support and second support relative to one another.

[0131] The second retention feature can latch the retention mechanism into the locked configuration when the second support is rotated towards the first support.

[0132] The second retention feature can latch the retention mechanism into the locked configuration when the second support reaches a position closest to the first support. Stated another way, the latching can occur at an end point of displacement of the second support. The second retention feature can latch the retention mechanism into the locked configuration when the second support is biased or pushed toward the first support.

[0133] The first retention feature may include a ledge on the first support.

[0134] The ledge can alternatively be described as a surface of the first support. The ledge can be a flat surface of the first support. When the second support rotates with the filter module received by it, the ledge can act to bias the filter module toward the ports. When the ledge engages the top surface of the filter module, thereby placing the retention mechanism in the locked configuration, the ledge can ensure that the filter module is properly received by the second support. The ledge can act as a buffer or detent to prevent the filter module from being disconnected from the ports when the retention mechanism is in the locked configuration.

[0135] Advantageously, the ledge is an easy to manufacture feature that provides the necessary restraint on displacement of the filter module to ensure proper placement of the filter module.

[0136] At least one of the first and second supports capable of receiving a filter module may further include a plurality of ports for connection to corresponding ports of the filter module.

[0137] The ports can alternatively be described as openings. The ports can include an inlet port and an outlet port. The plurality of ports can include one inlet port and two outlet ports. The plurality of ports can include female connectors. A corresponding male connector of the filter module can be received by the female connector. The plurality of ports is preferably provided as part of the second support. To allow rotation of the second support relative to the first support, the plurality of ports can be connected to the rest of the system (e.g., a printer) by a flexible hose. For example, the hose can include PTFE.

[0138] Advantageously, the multiple ports mean that the filter module can be easily connected to the filter module retention mechanism and to a wider system. Additionally, the multiple ports provide a convenient way to releasably engage the filter module with the surrounding retention mechanism.

[0139] The multiple ports may include multiple female connectors.

[0140] At least two of the plurality of female connectors can have different axial lengths. Each of the plurality of female connectors can have a different axial length. Stated another way, at least two of the plurality of female connectors can have different heights or axial extents.

[0141] In other embodiments, the retention mechanism can include a male connector and the filter module can include a female connector (ie, the arrangement is reversed).

[0142] Advantageously, by providing the female connectors with different axial lengths, the various ports of the filter module will disengage from their corresponding female ports at substantially different times when the filter module is removed from the filter module retention mechanism. This provides a gradual disengagement so that an operator can easily predict when the filter module will become disengaged. This is in contrast to, for example, an arrangement in which all of the connectors are the same size and therefore disengagement occurs simultaneously (which makes it difficult to predict when the filter modules will disengage and introduces the risk that the operator will lose or misplace the filter modules).

[0143] In use, the retention force exerted by the first retention feature can be in a first direction and the retention force exerted by the second retention feature can be in a second direction different from the first direction.

[0144] The retention force exerted by the first retention feature can be described as acting against a force exerted on the filter module by a fluid under high pressure as the fluid passes through the filter module. The retention force exerted by the first retention feature can be described as acting parallel to the axis of the plurality of ports. The retention force exerted by the first retention feature can be described as retaining the filter module in a generally axial direction. The retention force exerted by the first retention feature can be described as a filter module retention force. The retention force exerted by the first retention feature can act in a substantially linear direction. The retention force exerted by the first retention feature can act in a substantially horizontal direction in use. The first retention force can be described as being actable by the first retention feature.

[0145] The retention force exerted by the second retention feature can act in a generally rotational manner. Stated another way, the retention force exerted by the second retention feature can act to substantially prevent rotational separation between the first support and the second support. The retention force exerted by the second retention feature can be described as a latching force. The second direction in which the retention force exerted by the second retention feature acts can be a direction around a rotational axis defined between the first support and the second support. The retention force exerted by the second retention feature can be configured to counteract an axial reaction force of the filter module that wedges the first and second supports away from each other. This may be due, at least in part, to the arcuate, e.g., dome-shaped, top surface of the filter module. The second retention force can be described as being exertable by the second retention feature.

[0146] Advantageously, by having the first and second directions differ from one another, the force required to retain the filter module is substantially decoupled from the force required to latch the retention mechanism closed. Thus, the retention mechanism can provide a relatively strong retention force for the filter module, but does not require a commensurate force to remove the filter module from the retention mechanism. This is advantageous both for ensuring that the filter module remains retained during use, while avoiding difficulties when operators periodically remove the filter module for maintenance.

[0147] The filter module may be receivable by one of the first and second supports in an unlocked configuration, and the other of the first and second supports may include a sensor configured to detect the filter module in at least the locked configuration.

[0148] In the unlocked configuration, the first and second supports can be said to define a filter module-receiving volume. In the locked configuration, the first and second supports can be described as substantially surrounding the filter module.

[0149] Preferably, the first support includes a sensor configured to detect the filter module. Preferably, the sensor detects both that the filter module is properly received by the second support and that the second support is properly oriented relative to the first support, at least in the locked configuration. The sensor may be a magnetic sensor, such as a Hall Effect sensor. However, various other sensors may also be used.

[0150] Advantageously, the presence of a sensor for detecting the filter module can ensure that the system can only operate when the filter module is correctly received. This can prevent inadvertent operation of the system if the filter module is either not replaced or not installed correctly by mistake. The presence of the sensor can provide a fail-safe system that can only operate when the filter module is correctly installed.

[0151] The filter module retention mechanism may further include a release mechanism for releasing the filter module from the filter module retention mechanism.

[0152] The release mechanism can include a lever. The release mechanism can include a screw. The release mechanism can act to provide an release force that acts on the filter module to release it from the filter module retention mechanism. The release mechanism can utilize a mechanical effect to reduce the force required by an operator to remove the filter module.

[0153] The release mechanism can be mounted on at least one of the first and second supports, preferably the second support. That is, the release mechanism is preferably at least partially mounted on a movable or rotatable support. The release mechanism can include a pivot. The release mechanism can be utilized for the rear of the filter module and for filter modules proximate one or more of the plurality of ports. The release mechanism preferably provides at least a two-fold mechanical advantage multiplier that increases the force applied by an operator to easily release the filter module from the retention mechanism.

[0154] Advantageously, the presence of the release mechanism makes it easier to periodically remove the filter module from the mechanism for reasons such as maintenance.

[0155] The second support may be configured to receive the filter module in an unlocked configuration, and the first support may be a stationary support configured to hold the filter module in a locked configuration.

[0156] The second support being configured to receive the filter module in the unlocked configuration can alternatively be described as the second support being configured to receive the filter module when the second support is in a rotational position that is distal to the first support, or stated another way, the second support being configured to receive the filter module when the retention mechanism is in the open configuration.

[0157] The first support being a fixed support is intended to mean that the first support does not move when the filter module retention mechanism is transitioned between the unlocked and locked configurations. The retention mechanism may be fixed or attached to the overall printer by the first support.

[0158] The first support can be configured to directly engage the filter module. Alternatively, the first support can indirectly engage the filter module. In a preferred embodiment, the first support can be configured to engage the filter module in a number of different locations in the locking configuration. For example, a ledge on the first support can be configured to engage the top surface of the filter module in the locking configuration, while a clip on the first support is configured to engage a protrusion on the filter module in the locking configuration (to rotationally latch the first and second supports relative to one another).

[0159] The first support may include a second retaining feature.

[0160] Alternatively stated, the first support may include a clip.

[0161] According to an eleventh aspect disclosed herein, there is provided an assembly for a continuous ink jet printer including a filter module retention mechanism according to the tenth aspect of the invention and a filter module retained thereby.

[0162] Advantageously, when the filter module forms part of a continuous ink jet printer, the filter module can be held securely in place to offset the high forces exerted on the filter module by high pressure fluid pumped through it, yet can also be easily removed periodically for maintenance.

[0163] The second retention feature can engage the protrusion of the filter module in a locking configuration.

[0164] The protrusion on the filter module may alternatively be described as a handle on the filter module. The protrusion (e.g., handle) may be grasped by an operator when the filter module is inserted into the retention mechanism.

[0165] Advantageously, the protrusions are easy to position.

[0166] According to a twelfth aspect disclosed herein, there is provided a continuous ink jet printer comprising the assembly of the eleventh aspect of the invention.

[0167] According to a thirteenth aspect disclosed herein, there is provided a method of securing a filter module to a filter module retention mechanism of a continuous inkjet printer, the method comprising: biasing the filter module retention mechanism into an unlocked configuration in which the second support is distal to the first support; placing the filter module in engagement with one of the first and second supports so that the filter module is received by the one of the first and second supports; biasing the filter module retention mechanism into a locked configuration in which the second support is proximal to the first support by rotating the second support toward the first support to retain the filter module by a first retention feature of one of the first and second supports; and engaging a second retention feature of one of the first and second supports to latch the mechanism into the locked configuration and substantially prevent rotation of the second support relative to the first support.

[0168] Biasing the filter module retention mechanism into the unlocked configuration can include rotating the second support relative to the first support, which can be rotated up to about 20° to rotationally separate the second support from the first support to provide the filter module-receiving volume.

[0169] Placing the filter module into engagement with one of the first and second supports preferably includes placing the filter module into engagement with the second support, the filter module therefore preferably being received by the second support when the retention mechanism is in the unlocked configuration.

[0170] Biasing the filter module retention mechanism into the locked configuration can include rotating the second support relative to the first support, preferably by about 20 degrees of rotation. Providing the second support proximate to the first support can alternatively be described as the retention mechanism substantially surrounding the filter module. A first retention feature of one of the first and second supports can engage with the filter module to retain the filter module when the retention mechanism is biased into the locked configuration. Engaging the first retention feature of one of the first and second supports with the filter module to retain the filter module can include engaging a shelf of one of the first and second supports (preferably the first support) with the filter module (e.g., the top surface of the filter module). This can provide axial alignment of the filter module with the multiple ports. When the second support is rotated toward the first support, the first retention feature can at least partially cover or overlap the filter module (e.g., to limit displacement of the filter module). This can provide a detent that prevents the filter module from moving past the first retention feature. Retaining the filter module by the first retention feature can include at least partially aligning a ledge with (e.g., over) the filter module. The ledge can be described as a buffer or a cap.

[0171] Engaging the second retention feature of one of the first and second supports can include the second retention feature engaging one or more filter modules with the other of the first and second supports to rotationally lock the first and second supports relative to one another. In a preferred embodiment, the second retention feature is a clip provided as part of the first support, and the clip engages with the filter module (e.g., a protrusion thereof). The second retention feature preferably engages when the second support is rotated toward the first support. In other words, the rotational action or biasing actuation can automatically bias the clip so that the filter module engages the clip without the need for an operator to manually actuate the clip.

[0172] Substantially preventing rotation of the second support relative to the first support can include preventing rotation of the second support relative to the first support. Substantially preventing rotation can still allow a small degree of rotation, but not enough to remove the filter module from the filter module-receiving volume defined by the retention mechanism. Stated another way, the second support can be slightly rotatable relative to the first support, but not enough to remove the filter module from the retention mechanism.

[0173] Advantageously, the above-described method provides automatic retention of the filter module within a filter module retention mechanism that can securely hold the filter module while quickly allowing an operator to remove the filter module if required for maintenance. Furthermore, the first and second retention features preferably act to hold the filter module in different orientations such that the force required by an operator to remove the filter module is less than the retention force required to secure the filter module in use.

[0174] Placing the filter module in engagement with one of the first and second supports can include placing the filter module in engagement with the second support, and biasing the filter module retention mechanism into the locked configuration can include aligning a first retention feature of the first support with the filter module to retain the filter module, and biasing a second retention feature of the first support into the engaged state to latch the mechanism in the locked configuration.

[0175] Advantageously, biasing the filter module retention mechanism into the locked configuration as described above aligns the filter module with respect to the retention mechanism and then secures the retention mechanism in the locked configuration.

[0176] Placing the filter module into engagement with the second support can include inserting the filter module into a filter module-receiving volume defined by the second support. Placing the filter module into engagement with the second support can include inserting ports of the filter module into corresponding ports of the second support. The filter module can contact support members of the second support when the filter module is placed in the second support.

[0177] The second retention feature can engage the filter module.

[0178] The second retention feature can be described as directly engaging the filter module.

[0179] The second retention feature can engage a protrusion on the filter module.

[0180] The protrusion on the filter module that the second retaining feature engages may be described as the handle of the filter module.

[0181] Engaging the protrusion of the filter module with the second retention feature can include biasing a tapered engagement surface of the clip onto the protrusion of the filter module to latch the mechanism in the locked configuration.

[0182] Advantageously, the tapered engagement surface of the clip can provide automatic retention of the filter module by the clip. In other words, the clip can be elastically deformed by the action of the second support rotating relative to the first support, so that an operator does not have to manually deform the clip. Retention operation is therefore simplified as a result.

[0183] The method may further include detecting via a sensor that the filter module is properly seated in at least the locked configuration.

[0184] The sensor may be a magnetic sensor, such as a Hall effect sensor. The sensor may detect that the filter module is properly positioned on both the second support and the first support. Stated differently, the sensor may be configured to detect that the filter module is properly positioned in the retention mechanism. The sensor may be configured to detect that the filter module is aligned so that one or more ports of the filter module are in fluid communication with one or more corresponding ports of the second support. The filter module may be used to provide a signal to the locking arrangement indicating that the filter module has been properly received and that the printer can therefore be operated. Similarly, the sensor may act to prevent operation of the printer unless the filter module is properly seated in the locking arrangement.

[0185] It will be appreciated that features described in the context of one aspect can be combined with other aspects described herein. For example, features described above in the context of a filter module can also be applied to a continuous ink jet printer including such a filter module, or to a method of operating such an ink jet printer, or to a method of manufacturing a filter module, or to a kit of parts. In particular, it will be appreciated that a filter module according to the first, second, third, fourth, or fifth aspect can be used with a continuous ink jet printer according to the sixth aspect. Furthermore, the filter retention mechanism according to the tenth aspect can be used with a filter module according to the first, second, third, fourth, or fifth aspect, a continuous ink jet printer according to the sixth aspect, a filter housing according to the seventh aspect, and a method according to the eighth or ninth aspect. The assembly according to the eleventh aspect and the continuous ink jet printer according to the twelfth aspect can be used with any of the first through tenth aspects.

[0186] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0187] [Figure 1] 1 is a schematic diagram illustrating a continuous inkjet printer. [Figure 2] FIG. 2 is a schematic diagram showing the ink circuit of the continuous ink jet printer shown in FIG. 1. [Figure 3] 2 is a cross-sectional schematic view of an ink filter module for use in the continuous ink jet printer shown in FIG. 1. [Figure 4A] FIG. 4 is a schematic diagram illustrating components of an ink filter element of the ink filter module shown in FIG. 3. [Figure 4B] FIG. 4 is a schematic diagram illustrating components of an ink filter element of the ink filter module shown in FIG. 3. [Figure 4C] FIG. 4 is a schematic diagram illustrating components of an ink filter element of the ink filter module shown in FIG. 3. [Figure 4D]FIG. 4 is a schematic diagram illustrating components of an ink filter element of the ink filter module shown in FIG. 3. [Figure 5A] FIG. 4 is a schematic diagram illustrating components of the ink filter module shown in FIG. 3. [Figure 5B] FIG. 4 is a schematic diagram illustrating components of the ink filter module shown in FIG. 3. [Figure 5C] FIG. 4 is a schematic diagram illustrating components of the ink filter module shown in FIG. 3. [Figure 6] 4 is a schematic diagram showing the fluid flow paths within the ink filter module shown in FIG. 3. [Figure 7] 4A to 4C are diagrams illustrating a manufacturing process for the ink filter module shown in FIG. 3. [Figure 8] 10 is a schematic diagram illustrating an ink filter module having an alternative port arrangement. [Figure 9] 10 is a perspective view of an assembly including a filter module retention mechanism and a filter module according to another embodiment, shown in a locked configuration. FIG. [Figure 10] FIG. 10 is a cross-sectional side view of the assembly of FIG. [Figure 11] FIG. 11 is a rear view of the assembly shown in FIGS. 9 and 10. [Figure 12] FIG. 10 is a perspective view of an assembly according to another embodiment shown in an unlocked configuration. [Figure 13] 13 is a perspective view of an extract of the filter module retention mechanism of FIG. 12. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0188] In the figures, like parts are designated by like reference numerals. It will be appreciated that the drawings are for illustrative purposes only and may not be drawn to scale.

[0189] 1 illustrates schematically an inkjet printer 101. The printer 101 includes a main printer body 103 connected to a print head 105 by an umbilical cable 107. The main printer body 103 may include an ink supply system and a printer controller, and the main printer body 103 may have a display 109 (e.g., a touch screen) for use by an operator. The print head 105 is positioned to print on a substrate, such as the surface of an article 111 moving along a production line 113.

[0190] Referring now to FIG. 2, a simplified schematic diagram of a possible fluid system for the inkjet printer of FIG. 1 is shown. The inkjet printer 101 includes an ink supply system 115 enclosed within the printer main body 103. The ink supply system 115 includes an ink tank 117 for storing ink. A mix head 123 is located below the level of the ink tank 117 and is connected to an ink pickup line 119, which is itself connected to a pump 121. Thus, fluid within the ink tank 117 is in fluid communication with the pump 121, and ink also passes through the mix head 123. The pump 121 has an outlet connected to a 3:2 valve 122. The 3:2 valve is operable to connect the pump 121 to a filter 126 to enable ink to be supplied from the ink tank 117 to the printhead 105 (as described in more detail below). The 3:2 valve also allows the pump to be connected to a mix pickup 120 located within the ink tank 117.

[0191] The pump 121 can be operated in a forward or reverse direction. When the pump 121 is operated in a forward direction and the 3:2 valve 122 is configured to connect the pump outlet to the filter 126, the fluid system is said to be in a forward configuration. In the forward configuration, ink is drawn by the pump 121 from the ink tank 117 through the mix head 123 and the ink pickup line 119 towards the 3:2 valve 122. The pump drives the ink through the 3:2 valve 122 and then through the filter 126. The filter 126 has an outlet connected to the damper 125.

[0192] A damper 125 is provided after the filter 126 to reduce fluctuations in ink pressure within the ink supply. A pressure sensor 129 is provided at the damper outlet and configured to monitor the pressure at the damper 125 outlet. A valve 127 is provided downstream of the pressure sensor 129. An ink supply line 128 is configured to carry ink from the ink supply system 15 along the umbilical 7 to the printhead 5. The ink supply line 128 is connected to the ink pickup line 119 through the pump 121, the 3:2 valve 122, the filter 126, the damper 125, and the valve 127. Thus, in a forward configuration, ink is drawn from the ink tank 117 toward the printhead 105. The valve 127 is configured to control the supply of ink to the printhead 105.

[0193] The ink supply system 115 further includes an ink cartridge connection 131 that can be connected to an associated ink cartridge 133, and a solvent cartridge connection 135 that can be connected to an associated solvent cartridge 137. The ink cartridge 133 and the ink cartridge connection 131 are connected to an ink refill line 141, allowing ink to be drawn through a valve 143 by a pump 145 (e.g., a diaphragm pump) and delivered to the ink tank 117.

[0194] Similarly, the solvent cartridge 137 and solvent cartridge connection 135 are connected to a solvent refill line 149, allowing solvent to be delivered to the ink tank 117 through a valve 151 under the suction of a pump 145. Each of the valves 143, 151 can be independently actuated, allowing either ink or solvent to be delivered to the ink delivery tank independently of each other under the control of the pump 145.

[0195] In some configurations, ink and / or solvent reservoirs (not shown) may be provided for temporary storage of ink or solvent between the cartridges 133, 137 and the respective refill lines 141, 149.

[0196] To function properly, the ink supplied to printhead 115 must be within specified viscosity limits. Ink tank 117 acts as a reservoir of premixed ink so that the ink drawn therefrom conforms to viscosity specifications. The precise mixture of ink and solvent is maintained by controlled receipt of ink and solvent from ink cartridge 133 and solvent cartridge 137.

[0197] As described above, in use, ink is delivered to the printhead 105 through the umbilical 107, along the ink pickup line 119 and the ink supply line 128. Within the printhead 105, ink is supplied to the droplet generator 155. The ink is supplied to the droplet generator under pressure (under the influence of the pump 121) and forced through the nozzles of the droplet generator 155 to form ink jets 157. The ink jets 157 begin as a steady stream of ink that, under the influence of surface tension and vibrations applied within the droplet generator 155 (e.g., by a piezoelectric oscillator), gradually breaks up into a series of ink droplets 159 that continue to travel in the direction of the ink jet 157.

[0198] In some printers (such as that shown in FIG. 2 ), a purge line 158 is connected to the droplet generator. The purge line 158 may be connected to a purge port on the droplet generator 155. The droplet generator 155 may be provided as part of a droplet generator assembly including a droplet generator body with known acoustic properties and a piezoelectric oscillator. The purge port may be provided by this body or a separate part connected thereto. The purge line 158 allows ink to flow out of the droplet generator through a purge opening without passing through the nozzles, further enabling the droplet generator to be cleaned. The purge line 158 extends from the droplet generator 155 along the umbilical 107 and returns ink (or solvent) to the ink delivery tank 117 depending on the phase of operation. One or more valves (not shown) may be provided in the purge line 158. It will be understood that the purge line is not essential and may be omitted in some printers. Furthermore, additional fluid lines may be provided to support certain printer operations. For example, a solvent supply line may be provided to allow a cleaning solvent to be supplied to the printhead for cleaning purposes.

[0199] Immediately after ejection from the nozzle of the droplet generator 155, the ink jet 157 is passed through a charging electrode 161. The point at which the continuous ink jet 157 breaks up into droplets 159 is positioned to occur within the charging electrode 161. The ink is a conductive liquid, and the droplet generator is conventionally held at a fixed (e.g., ground) potential. A variable voltage is applied to the charging electrode 161, which induces a charge in the continuous ink stream extending from the ink droplet generator 155 toward the charging electrode 161. When the continuous ink stream (i.e., the ink jet 157) breaks up into droplets 159, any charge induced in the ink within the droplets becomes trapped at the moment the individual droplets break off from the main ink stream 157. In this way, a variable charge can be applied to each of the ink droplets within the stream of ink droplets 159.

[0200] The stream of ink droplets 159 then continues passing from charged electrode 161 through an electrostatic field. In the illustrated example, the stream of ink droplets 159 passes between deflection electrodes 163 and 165. A first one of the deflection electrodes 163 is held at a first voltage, while a second one of the deflection electrodes 165 is held at a second voltage, establishing a large potential difference (e.g., 8-10 kilovolts) between the deflection electrodes 163 and 165. In some systems, one electrode can be held at ground potential while the other electrode is held at a high (positive or negative) voltage (relative to ground). In other systems, one electrode is held at a negative voltage (relative to ground) and the other electrode is held at a positive voltage (relative to ground). In yet another variation, only a single deflection electrode is provided, or multiple deflection electrodes are provided. The electric field established by deflection electrodes 163, 165 deflects any charged droplets (i.e., those charged by charging electrode 161). In this way, based on the variable charge applied by electrode 161, droplets 159 can be selectively (and variably) steered from the path they were following as they were ejected from the nozzle of droplet generator 155.

[0201] Droplets that pass through the deflection field without being deflected proceed to a gutter 167. The gutter 167 contains an orifice through which the droplets enter. The gutter 167 is connected to a gutter line 169 that extends from there back to the ink supply system 115. A valve 171 is optionally provided in the gutter line 169 to allow the line to be opened and closed. Suction is applied to the gutter line 169 by a suction system to draw ink along the line from the gutter back towards the ink supply system 115.

[0202] In many inkjet printers, suction is provided by a suction system that includes a venturi 173 (sometimes called a jet pump). The venturi 173 is provided within the ink supply system 115 and is configured to receive a pressurized flow of ink from the ink pump 121 through a venturi supply line 175 that is connected to a second outlet of the filter 126. After passing through the venturi 173, the ink flows from the venturi supply line 175 through the venturi 173 and returns to the ink delivery tank 117 through an ink return line 177.

[0203] A venturi comprises a conduit having a converging and then diverging cross section. The venturi creates a localized high-velocity, low-pressure region through a constriction. The high-velocity, low-pressure region is in communication with suction port 178. In use, gutter line 169 is connected to venturi 173 through suction port 178. In this manner, suction is applied to gutter line 169 using the low-pressure region achieved within venturi 173.

[0204] Any ink that flows into the gutter 167 will be forced along the gutter line 169 and will eventually be sucked into the venturi 173 (through the suction port 78), from where it will flow along the return line 177 and then back into the ink delivery tank 117.

[0205] By using the venturi in this manner (i.e., as a jet pump), it is possible to design a system in which the main system ink pump 121 can generate both positive pressure (e.g., to supply ink to the printhead) and negative vacuum pressure (e.g., to provide gutter suction).

[0206] The ink tank 117 is vented by a vent 179 to prevent excessive pressure from building up within the ink tank 117. However, it will be understood that venting air through the vent 179 may cause solvent vapors to escape into the external environment, which may be considered undesirable (e.g., due to the need to replace the solvent and potential environmental harm). In some embodiments, a capture system 180 may be connected to the vent 179 to capture solvent from the vented air. The capture system 180 may include a condenser. The captured solvent may be returned to another location in the ink supply system 115, for example, to the ink tank 117. The capture system 180 may be connected to the pump 145.

[0207] Above, filter 126 has been described as filtering ink for delivery to the printhead through ink supply line 128 and to the venturi 173 through venturi supply line 175. However, it will be appreciated that in an alternative arrangement, separate filters may be used. That is, a first filter may be provided for finely filtering the relatively small amount of ink delivered to the printhead, while a second filter may be provided for more coarsely filtering the larger amount of ink delivered to the venturi 173.

[0208] An ink filter module 300 capable of performing the dual filtration functions of the filter 126 described above will now be described in detail with reference to FIGS.

[0209] 3 illustrates a schematic cross-sectional view of an ink filter module 300. The ink filter module 300 includes a filter housing 301 including a connecting portion 302 and a body portion 303. The connecting portion 302 includes an inlet port 305, a first outlet port 307, and a second outlet port 309. These three ports are located at an end portion 302a of the connecting portion 302. The connecting portion 302 further includes a sidewall 302b. The filter module further includes a first filter element 311 and a second filter element 313. The sidewall 302b at least partially surrounds the first filter element 311. The body portion 303 includes an end portion 303a and a sidewall 303b. The sidewall 303b at least partially surrounds the first filter element 311.

[0210] Filter housing 301 includes walls 315 (including end portions 302a, 303a and side walls 302b, 303b) that define an enclosed filter chamber 317. Filter chamber 317 is fluidly connected to inlet and outlet ports 305, 307, 309, respectively.

[0211] First filter element 311 is centrally disposed within filter chamber 317. An outer cavity 319 is defined within filter chamber 317 on the exterior of first filter element 311. First filter element 311 is shown in more detail in FIGS. 4A-4D. FIG. 4A shows first filter media 321 in a perspective view. First filter media 321 is a pleated filter media. First filter media 321 is cylindrical and has a central cavity 323 with a central axis AA extending therethrough. First filter media 321 includes a polypropylene filter.

[0212] 4B shows a perspective view of the first filter media 321 surrounded by a pleated protective filter 325. The pleated protective filter 325 can be made from a material, such as stainless steel, that is more resistant to chemical attack by ink than the material of the first filter media 321.

[0213] The pleat protection filter 325 surrounds the outer surface of the pleated filter media and also has a cylindrical shape. The presence of the pleat protection filter 325 is optional, but when present, it can extend the life of the pleated filter media. In particular, the pleated filter media may deteriorate over time, and portions of the pleated filter material may become loose from the majority of the first filter media 321. The pleat protection filter 325 can prevent any loose portions of the pleated filter media from mixing with ink in the filter chamber 317 and / or being carried away from the first filter element 311.

[0214] First filter element 311 further includes a central support 327 (partially shown in FIG. 4B) disposed in central cavity 323. Central support 327 includes a coarse lattice of polypropylene support elements and is provided to prevent collapse of first filter media 321.

[0215] 4C and 4D, first filter element 311 further includes first end closure 328 (omitted from FIG. 4C) and second end closure 329. First end closure 328 is provided at a first end 330 of first filter element 311, and second end closure 329 is provided at a second end 331 opposite first end 330.

[0216] First filter element 311 further includes first filter element outlet port 333 centrally disposed on first end closure 328 and configured to permit ink flow from central cavity 323. First end closure 328 further includes ejection screen 334 (visible in cross section in FIG. 3 ) configured to prevent pleated media debris from exiting central cavity 323 through port 333.

[0217] Figure 5A shows the housing connecting portion 302 separately, which has a circular cross section when viewed along axis AA (as also shown in Figure 4A). Figure 5B illustrates where the first filter element 311 is inserted into the housing connecting portion 302. The first filter element outlet port 333 (see Figure 4D) is inserted into the first filter element connection 335 (see Figure 5A) provided by the housing connecting portion 302.

[0218] FIG. 5C shows the fully assembled filter module 300, in which case the housing body portion 303 is also shown as being present.

[0219] The filter module 300 further includes a presence detection feature which, in the illustrated embodiment, includes a magnet support 337 having an opening 339 for receiving a magnet (not shown).

[0220] The filter module 300 further includes a removal handle 341 (not shown in FIG. 3 but shown in FIG. 5C ) provided at the second end 331. That is, the removal handle 341 is provided as part of the body portion 303 and is located at the end of the filter module opposite the inlet port 305 and outlet ports 307, 309. The removal handle 341 allows a user to grip the filter module 300 to apply a pulling force to enable easy removal of the filter from the printer. Although not shown in all figures, the removal handle 341 (if present) can further include one or more openings. Preferably, the removal handle includes two openings. These openings provide openings that allow a user to grip and manipulate (e.g., pull) the filter module 300.

[0221] The filter further includes an engagement structure 343 for engaging a complementary structure on the printer to secure the filter in an installed configuration. In the illustrated embodiment, the engagement structure 343 is incorporated into the handle 341. The engagement structure 343 allows the filter to rigidly engage with the printer. Providing a secure engagement between the filter and the printer mitigates accidental release or ejection of the filter when the filter is placed under pressure caused, for example, by pumping ink therethrough.

[0222] 5A also shows (optional) inlet filter 345 (mostly hidden) and second filter element 313. Second filter element 313 includes second filter media 314, such as stainless steel mesh filter media. Second filter element 313 is disposed within filter housing 301. In particular, second filter element 313 is received within the portion of the filter housing that defines second outlet port 309, as shown most clearly in FIG.

[0223] The first filter media 321 has a first absolute rating. The second filter media 314 has a second absolute rating. The first absolute rating is different from the second absolute rating. The term "absolute rating" is sometimes referred to as the filter's cutoff point or absolute micron rating. Such a rating defines the maximum particle size that can pass through the filter element's filtration media. In use, it is expected that less than 1% of particles larger than the absolute filter rating will pass through the filter. An alternative filter definition is a nominal rating, which allows around 5% of particles larger than this rated size to pass through even in normal operation. Thus, a filter can be defined by either a nominal rating or an absolute rating. In either case, the filter can be said to remove particles larger than a predetermined size from the filtrate.

[0224] The absolute rating of the second filter media 314 is greater than the absolute rating of the first filter element 321. The nominal rating of the second filter media 314 is greater than the nominal rating of the first filter element 321.

[0225] In one example, the absolute rating of the second filter media 314 is 20 μm. The second filter element 313 can take the form of a top hat filter, a disc filter, or any convenient shape. The second filter media 314 can be formed from a solvent-compatible material, such as stainless steel, that is highly resistant to working in solvent-based inks.

[0226] The first filter element 321 may have an absolute rating of 40 μm and a nominal rating of 10 μm. The pleated protection filter 325 may have an absolute rating of 40 μm.

[0227] In practice, filter ratings are selected to provide sufficient protection for the orifices they protect, so that a printhead and associated nozzles (which may have orifices on the order of tens of microns, e.g., 30-75 microns) will typically be protected by a finer filter than would a venturi (which may have orifices on the order of hundreds of microns or even larger, e.g., 300 microns to 1.5 mm).

[0228] Each of the first filter media 311 and the second filter media 314 further has an effective surface area that, together with the rating, determines the rate at which ink will pass through the respective filter and the rate at which filter performance will degrade over time. The term effective surface area refers to the total area of ​​the filter media exposed to the fluid stream that is available for filtration. Such effective surface area may be significantly greater than the geometric area of ​​the filter media when a depth filter is used (e.g., foam, multi-layer filter, or random fiber filter).

[0229] A filter having only a small effective surface area will deteriorate faster than a filter having a large effective surface area (for the same rating). Therefore, the effective surface area of ​​each filter media will be selected to accommodate convenient expected maintenance intervals. For example, the second filter media 314 can be selected to have a large enough area so that substantially all dust drawn into the system through the gutter 67, all ink condensates of such dust, water, oil, and food and beverage vapors from the factory environment, and all debris from the pleated filter and its housing can be captured by the second filter element 313 after one year of operation without causing an excessive pressure drop across the second filter element 313.

[0230] The effective surface area of ​​each filter will also be selected to provide a sufficient fluid passage rate; that is, an excessively large filter may result in an excessively slow fluid flow rate and associated high settling. Furthermore, because it is preferable to remove the contents of the filter module 300 (e.g., into the ink tank 17) during shutdown, the total fluid volume of the filter module 300 should be minimized. It will be appreciated, therefore, that the optimal size for each filter will depend on the particular performance and maintenance requirements for the printer 1.

[0231] The effective surface area of ​​the first filter media 321 is significantly greater than the effective surface area of ​​the second filter media 314 .

[0232] During normal use, the ink flow rate through second filter element 314 is greater (e.g., at least twice as great) than the ink flow rate through first filter element 311. For example, during normal use, the ink flow rate to printhead 5 may be approximately 4-6 milliliters per minute, while the ink flow rate through venturi 73 may be approximately 100 times greater than the ink flow rate to printhead 5.

[0233] The first filter element 311 has a cylindrical shape. Conveniently, such a shape provides a large area through which ink can pass. Advantageously, the overall flow rate of ink through the filter module 300 can be kept above a predetermined minimum flow rate, thereby reducing the likelihood of sediment buildup within the first filter element 311 while allowing a desired flow rate of ink to pass from the inlet port 305 to the first outlet port 307.

[0234] The second filter element 313 also has a cylindrical shape. The second filter media 314 comprises a mesh filter, such as, for example, a stainless steel mesh filter.

[0235] The nominal rating of the first filter element 321 is determined by the pleated filter media. The absolute rating of the first filter element 321 is determined by the exit screen 334. Therefore, the performance of the first filter element is determined primarily by the pleated filter media, not the pleated protective filter 325, the support structure 327, or the exit screen 334. That is, the minimum nominal rating is determined by the first filter media 311 operable to reject the majority of particles rejected by the filter element 321.

[0236] In an alternative arrangement, the first filter media 321 can include a stainless steel mesh filter media. For example, the first filter media can be a stainless steel depth filter. Advantageously, it is believed that the component count of the first filter element is minimized. Alternatively, the first filter media can include a polypropylene mesh or a PTFE mesh.

[0237] The exit screen 334 can be stainless steel mesh, allowing the printer to continue operating without significant component damage for a short period of time, even after significant degradation of the pleated first filter media 321. Alternatively, the exit screen 334 can be formed from a solvent-compatible material that is highly resistant to operating in solvent-based inks. The exit screen 334 can have similar absolute ratings as the first filter media 321.

[0238] 3, when filter module 300 is fully assembled, first filter element 311 is disposed within filter chamber 317. First end closure 328 abuts the interior wall of filter housing 301 to secure the location of first filter element 311 within housing 301. Second end closure 329 may be spaced from the interior wall of filter housing 301. First filter element 311 defines a generally cylindrical sidewall extending between first end 330 and second end 331.

[0239] 3, filter module 300 is shown in its "in use" orientation, i.e., when installed in printer 100, filter module 300 is oriented with axis AA aligned horizontally and the positive z direction corresponding to the direction opposite gravity.

[0240] An inlet port 305 is provided at the bottom, a first outlet 307 in the centre and a second outlet port 309 at the top. In use, ink is pumped by the ink pump 21 into the inlet port 305, out the first outlet port 307 (to feed the printhead 5) and out the second outlet port 309 (to feed the venturi 73).

[0241] The filter module is particularly suited for filtering pigmented inks, such as hard pigmented inks, in continuous ink jet printers of the type described with reference to FIGS. 1 and 2. By positioning the filter module 300 so that ink can pass through a first filter element 311 having a different absolute rating (or effective pore size) than a second filter element 313, it is not necessary to filter all of the ink in the filter module to the purity required for use in the printhead 5. Instead, only the (relatively small) flow rate of ink required to supply the printhead is filtered to the desired level of filtration. The remaining ink can pass through a second filter element 313 having a different absolute rating (or effective pore size) for more coarse filtration. Such a filter (i.e., the second filter element 313) can prevent larger debris or particles from reaching the venturi 73. However, it was recognized that filtering all of the ink at a high absolute rating could result in excessive degradation of filter performance and shorter maintenance intervals (to replace clogged ink filters).

[0242] Furthermore, providing the first filter element 311 and the second filter element 313 in a single filter housing (i.e., housing 301) allows for easy replacement of the filter module 300, reducing printing system downtime and minimizing waste. It will be appreciated that the first filter element 311 and the second filter element 313 can be designed to be expected to require replacement at similar times to minimize unused filter capacity.

[0243] FIG. 6 illustrates a schematic cross-sectional view of filter module 300. A first filtrate path 350 is defined from inlet port 305 through first filter media 321 to first outlet port 307. The first filtrate path 350 is shown passing through first filter media 321 at filtration location 351. First filtrate path 350 then emerges into central cavity 323 and then exits through first filter element outlet port 333, first filter element connection 335 (provided by housing connection portion 302), and first outlet port 307. Thus, filtrate 350F exiting first outlet port 307 includes a portion of the fluid flowing into inlet port 305 that was filtered by first filter media 321. There is no path from inlet port 305 to first outlet port 307 that does not pass through first filter media 321. The first filtrate path may be referred to as the "flow-through" path (with respect to the first filter media 321), i.e., the filtrate 350F flows through, and is therefore filtered by, the first filter media 321.

[0244] Second filtrate path 352 travels from inlet port 305 onto the exterior surface of first filter element 311 within outer cavity 319, then through second filter media 314 to second outlet port 309. Second filtrate path 352 passes through second filter media 314 at filtration location 353 and then exits through second outlet port 309. Thus, filtrate 352F exiting second outlet port 309 includes a portion of the fluid entering inlet port 305 that was filtered by second filter media 314. Second filtrate path 352 effectively bypasses first filter element 311. While second filtrate path 352 is shown passing around second end 331 of first filter element 311, it will be appreciated that there are several paths that make up second filtrate path 352. Some of these paths pass around the circumference of first filter element 311. For example, second filtrate pathway 352 includes a pathway defined between the exterior surface of first filter element 311 and a wall of the main chamber defined by filter housing 301 .

[0245] The other part of the second filtrate pathway 352 can pass around the first end closure 328 (while bypassing the first filter outlet 333). Thus, the second filtrate pathway effectively surrounds the outermost or exterior surface of the first filter element 311. However, it will be appreciated that the second filtrate pathway need not completely surround all sides of the first filter element. That is, ink flowing to the second outlet port 309 passes over a portion of the outermost surface of the first filter element (e.g., the sidewall of the filter element) or the pleated protection filter 325.

[0246] The second filtrate path may be referred to as the "cross-flow" path (again with respect to the first filter media 321), i.e., filtrate 352F flows across the face of the first filter element 311 but is not filtered by the first filter element 321.

[0247] A third filtrate path 354 is defined from inlet port 305 through first filter media 321, then through second filter media 314, to second outlet 309. It is shown how third filtrate path 354 passes through first filter media 321 at filtering station 355. Third filtrate path 354 then emerges into central cavity 323, then exits (a second time) through filter media 321 at filtering station 356, to outer cavity 319 surrounding first filter element 311. The third filtrate path then passes between housing 301 and filter element 311, then through second filter media 314 at filtering station 357, and then exits through second outlet port 309. Thus, filtrate 354F exiting second outlet port 309 includes the second filter media 314 as well as a portion of the fluid flowing into inlet port 305 that was filtered (twice) by first filter media 321. The third filtrate path may be referred to as the "counterflow" path (again with respect to first filter media 321). That is, the filtrate flows through first filter media 321 a first time and a second time in a direction opposite to the primary bulk flow direction. The passage of filtrate through the first filter element a second time and out into the surrounding outer region "backwashes" the first filter element. The flow of filtrate in the opposite direction to the first filtrate path reduces the extent to which filtered particles are retained by the first filter media.

[0248] The provision of crossflow and backflow filtrate paths allows a higher overall flow rate of ink to pass through the filter module than would occur if only flow to the printhead flowed through the filter. Such a higher overall flow rate is particularly advantageous because it reduces the likelihood that any sediments in the ink will deposit in the first filter element. The filter housing 301 is sized and configured to vary the desired crossflow, throughflow, and backflow rates depending on the printer requirements.

[0249] The second filtrate path 352 (crossflow) represents the majority of the total ink flow within the filter, given the flow restrictions within the relatively limited path compared to the first filtrate path 350, which must pass through the first filter element 311. Of course, it will be appreciated that the flow rate through the filter module 300 and the relative flow distribution between the first, second, and third filtrate paths can be varied by changing the size of the gap between the first filter element 311 and the filter housing wall 315 and by varying the characteristics of the first filter element 311 itself. In some situations, flow along the third filtrate path can be minimized or even negligible. However, at other times (e.g., during refilling of the filter chamber 317), the flow of air and / or ink along the third filtrate path may be more significant. It will also be appreciated that a clear distinction between the different filtrate paths may not be possible in all cases. The flow of fluids (ink and air) within the filter module 300 can be complex and turbulent.

[0250] It should also be noted that fluid flow through the pleated first filter media 321 (whether as part of the first filtrate path 350 or the third filtrate path 354) may often include fluid elements that flow across the face of the first filter media 321 before finding a path through the pleated filter media.

[0251] The first, second, and third filtrate paths 350, 352, 354 are paths along which ink can flow within the filter module 300 during normal operation of the printer.

[0252] As shown in FIG. 3 , when the filter module 300 is configured for use, the first outlet port 307 and the second outlet port 309 are positioned vertically above the inlet port 305. The first outlet port 307 and the second outlet port 309 can be seen to be vertically (i.e., in the z-direction) spaced apart from the inlet port 305. Thus, the outlet ports 307, 309 are provided at elevated positions on the filter housing 301 when the filter module 300 is installed for use. Thus, during normal use, the first, second, and third filtrate paths each include a vertically upward component from the inlet port to the first and second outlet ports. Thus, the filter module 300 is positioned to direct ink flow in a generally upward direction from the inlet port 305 to the first and second outlet ports 307, 309. Thus, ink flow through each of the first, second, and third filtrate paths can be generally upward. Advantageously, this reduces the likelihood of sediment settling within the filter.

[0253] Flowing in an upward or substantially upward direction includes ink flowing in a direction that includes a perpendicular component, in other words, the ink flow direction includes a component that is opposite to the force of gravity.

[0254] Thus, the overall flow of ink through the filter chamber 317 can be substantially upward. Advantageously, this reduces the likelihood of sediment deposits in the filter module 300. Flowing ink upward is also advantageous for emptying the filter following and during shutdown. Emptying the filter during shutdown reduces sediment and pigment deposits. Nevertheless, some resin may accumulate on the pleated surface of the first filter element 311, thereby clogging the filter. When ink is resupplied to the filter after shutdown, the deposited resin is backwashed and becomes suspended in the ink, preventing it from clogging the first filter element 311. Enabling the filter to be emptied in this manner can extend the life of the first filter element 311 and the second filter element 313.

[0255] 3, it can be seen that first outlet port 307 and second outlet port 309 are vertically separated from one another. In particular, second outlet port 309 is positioned vertically above first outlet port 307. While this positioning is not essential (it is contemplated that the outlet ports could be in similar vertical locations or reversed), providing an outlet (e.g., second outlet 309) at the top of housing 301 allows for the introduction of air into filter chamber 317 when draining filter module 300 (e.g., over a planned downtime) and for air to be exhausted from filter chamber 317 when refilling the filter module after draining.

[0256] In other words, the inlet port 305, the first outlet port 307, and the second outlet port 309 may each define a center of gravity, and the vertical distance between the center of gravity of the inlet port 305 and the center of gravity of the second outlet port 309 may be greater than the vertical distance between the center of gravity of the inlet port 305 and the center of gravity of the first outlet port 307. Thus, in use, more work must be done against gravity to pump ink into the second outlet port 309 compared to pumping ink into the first outlet port 307.

[0257] The second outlet port 309 can be immediately vertically above the first outlet port 307 (as shown). However, in some variations, the second outlet port 309 can be located in a region of the filter housing that is spaced vertically above the first outlet port 307, but not necessarily in the same plane or directly above the first outlet port 307 in the z-direction. An offset in either the x- or y-direction can be applied.

[0258] Providing the second outlet port 309 vertically above the first outlet port 307 is advantageous because, in use, any air within the chamber 317 can exit the filter housing 301 through the second outlet port 309 rather than through the first outlet port 307, which can be connected to the printhead 5. Thus, any air bubbles that may become trapped within the filter housing 301 can be easily removed without passing through to the print nozzles. The second outlet port 309 can be provided at the top of the chamber 317, which allows any air remaining in the filter to be vented. Of course, this advantage can be achieved even if the second outlet port 309 is not exactly at the top of the chamber 317.

[0259] As described above, ink flows along the first filtrate path 350 in a direction generally opposite to the direction of gravity. Similarly, ink flows along the second filtrate path 352 in a direction generally opposite to the direction of gravity. Furthermore, ink flows along the third filtrate path 354 in a direction generally opposite to the direction of gravity.

[0260] In the event of an unexpected power loss, any pigment will deposit toward the bottom of chamber 317 (i.e., in the negative z direction as shown in FIG. 3). By locating inlet port 305 near the bottom of filter module 300, pressurized ink entering the filter upon system start-up will agitate any deposited ink pigment, causing the pigment to remix. However, it will be appreciated that port inlet 305 need not be immediately adjacent to chamber 317 to achieve this benefit.

[0261] During planned printing shutdowns, the contents of the filter chamber 317 can be drained into the ink tank to reduce the risk of precipitation within the filter module 300. During such shutdowns, the filter can be maintained in a saturated vapor environment to minimize ink drying and reduce difficulties associated with rewetting. This can be achieved by maintaining a fluid connection between the solvent-saturated atmosphere within the ink tank 117 and the internal volume of the filter chamber 317. Such a filter procedure can tolerate shutdowns of approximately one month or more.

[0262] Upon start-up after a shutdown period, the pump 21 can be arranged to provide a higher flow rate through the filter module 300. This facilitates remixing of any sediment or resin that may have deposited within the filter module 300, particularly within or on the first filter element 311 and / or second filter element 313, thus reducing the likelihood of blockage of the first and second filter elements 311, 313.

[0263] During the start-up process, when the filter chamber 317 is refilled with ink, the above-described first, second, and third filtrate paths 350, 352, 354, along with the configuration of the inlet and outlet ports 305, 307, 309 of the filter module, will allow substantially all air to be evacuated from the chamber 317 in an efficient manner. In particular, when ink is reintroduced to the inlet 305, the level of ink in the chamber will begin to increase around the first filter element 311. A portion of the ink will pass along the first filtrate path 350 through the first filter element into the central cavity 323 and then exit the cavity 323 through the first outlet port 307. The majority of the ink will pass along the second filtrate path 352 through the outer cavity 319, around the first filter element 311, and then exit the cavity through the second outlet port 309 and the second filter element 313.

[0264] Air in chamber 317 will be expelled primarily through second outlet port 309. However, it will be appreciated that the rising level of ink will typically displace air in central cavity 323 at a rate higher than can be accommodated by first outlet port 307 (which typically allows a flow to the printhead of approximately 4-6 ml per minute). Thus, air in central cavity 323 will be expelled through the upper portion of the first filter element into outer cavity 319. This flow of air and then ink will follow third filtrate path 354, as described above. This process of air and ink flowing through first filter element 311 (e.g., at filtration location 356) (including periods of mixed flow) will exert a cleaning effect on first filter media 321. In some embodiments, first outlet port 307 can be selectively closed using one or more valves. In this way, by closing the first outlet port 307 so that air and / or ink cannot exit the central cavity 323 through the first outlet port 307, the exhaust of air from the central cavity 323 through the print head is avoided, and instead substantially all of the air can be exhausted to the outer cavity 319 and then through the second outlet port 309.

[0265] Eventually, after extended use, it will be necessary (or at least advisable) to replace the filter module 300 within the printer 1. By locating the inlet port 305, first outlet port 307, and second outlet port 309 on a single side of the filter housing 301 (i.e., at the first end 330), the filter module can be installed and removed with simple operations.

[0266] The filter module 300 can be removed by pulling on a removal handle 341 (not shown in FIG. 3) in the axial positive x-direction. The removal handle allows a user to grasp the filter and apply a pulling force to allow easier removal of the filter from the printer.

[0267] A replacement filter module can be installed by aligning ports 305, 307, 309 with the corresponding female ports provided by the printer and pressing the filter into place. Mechanical guide features (not shown) can be provided to ensure correct orientation and alignment.

[0268] The printer 1 can be configured to detect when a new filter module has been installed. For example, the filter module 300 can include a presence detection feature configured to interact with a detector provided by the printer. In the illustrated embodiment, the presence detection feature includes a magnet inserted into the opening 339 and supported by the magnet support 337. The printer 1 includes a Hall Effect sensor positioned to detect the magnet. Other suitable presence detection mechanisms and motion sensors can be provided. The presence detection mechanism can be used to control the operation of the pump 21 and, therefore, the flow of ink into the inlet port 305.

[0269] The magnet support 337 may also function as an alignment feature (although it is contemplated that alternative features, such as protruding members or ribs extending from the sides of the filter housing, may be provided). This feature is advantageous as it ensures the correct orientation of the filter module when installed in the printer. In some arrangements, the filter module may be symmetrical. However, if it is not (e.g., if no inlet filter 345 is provided), it may be important that the second outlet port 309 is the top port and the inlet port 305 is the bottom port in use.

[0270] The filter further includes engagement structure for engagement with complementary structure on the printer to secure the filter in an installed configuration. By providing a secure engagement between the filter and the printer, accidental release or ejection of the filter when placed under pressure caused, for example, by pumping ink through the filter is mitigated.

[0271] The filter module 300 has been described above in the context of a particular type of continuous ink jet printer 1. However, it will be appreciated that alternative ink circuits or printer types may be used. Thus, the filter module 300 may be used in combination with a continuous ink jet printer that includes an ink circuit that typically includes an ink tank (e.g., tank 17) and an ink pump arrangement (e.g., pump 21).

[0272] As mentioned above, the printer 1 includes a pressure sensor 29. The pressure sensor is configured to sense the pressure in the ink supply line 28 downstream of the filter module 300 (i.e., downstream of the first outlet port 307).

[0273] In some embodiments, a pressure sensor can be provided to measure the pressure drop between the inlet port 305 and the first outlet port 307. Alternatively or additionally, a pressure sensor can be provided to measure the pressure drop between the inlet port 305 and the second outlet port 309. In this manner, the pressure drop across the first filter element 311 and / or the second filter element 313 can be measured. In some embodiments, a single pressure sensor can be configured to sense pressure at multiple locations, for example, by being connected to the first outlet port 307 and the second outlet port 309 through a switchable valve arrangement (not shown).

[0274] Sensing the pressure drop across the first and / or second filter elements can be used to determine when the first and / or second filter elements 311, 313 need to be replaced. The measured pressure change across the first and / or second filter elements can be compared to known or tested pressure drops to determine when the first and / or second filter elements need to be replaced or cleaned. The pressure drop can be measured during printer startup or shutdown. When the pressure drop reaches a predetermined value, it can indicate that the first and / or second filter elements need replacement. The pressure sensor can be coupled to a printer controller. Such a printer controller can be configured to control the printer based on the pressure readings (e.g., adjust the pump flow rate depending on the pressure readings) to maintain a desired pressure in the ink supply line 28 and a desired flow rate through the venturi 73 despite filter degradation.

[0275] In some examples, a pressure sensor is provided to sense the pressure at each of the two filter outlet ports 307, 309. Such an arrangement is particularly advantageous when the filter has two outlet ports 307, 309, because blockage of the first filter element 311 cannot be detected based on a pressure sensor monitoring only the pressure downstream of the second filter element 313, and vice versa. If only a single pressure sensing location is provided (e.g., in the ink supply line 28), it may be expected that the printer will fail to compensate for the loss of venturi flow, resulting in reduced gutter suction and ultimately a loss of ink return.

[0276] Pressure sensor readings can be performed during printing or when printing is not occurring. Indeed, filter degradation is typically a process that occurs over time. Therefore, pressure sensing can be performed during start-up or shutdown sequences. Such operation can allow convenient use of a single pressure transducer, which is sequentially connected to various pressure sensing locations (e.g., inlet port 305, ejection port 307, and ejection port 309), with the printer controller then taking appropriate action (e.g., modifying pump control signals in light of pressure readings and / or issuing an alert).

[0277] The filter module 300 has been described above in assembled form. However, it will be appreciated that the components of the filter module 300 may be provided separately. For example, the first filter housing component and the second filter housing component (i.e., the connecting portion 302 and the main body portion 303) may be provided separately. As shown by FIG. 7 , the filter module 300 may be constructed according to the following steps during the manufacturing process:

[0278] In a first step S1, pleated media is obtained and cut to size. In a second step S2, the cut pleated media is formed into the cylindrical form of the first filter media 321 shown in FIG. 4A by welding (e.g., sonic welding) the seams between its ends. In a third step S3, the welded pleated media (i.e., first filter media 321) is assembled with a central support 327 and a pleat protection filter 325. In step S4, an injection screen 334 is welded to a first end closure 328.

[0279] In step S5, the assembled first and second end closures 328, 329 are welded to opposite ends of the first filter media 321 having the central support 327 and pleated protection filter 325. An O-ring 333a is provided around the first filter element outlet port 333. The first and second end closures 328, 329 are both welded together (e.g., by heat welding). The assembled components are shown in FIG. 4D (shown without the O-ring 333a). It will be appreciated that steps S1, S2, and S3 can be performed in parallel with step S4, but must always be performed before step S5.

[0280] In a subsequent step S6, the housing protection portion 302 is provided. In step S7, filters are inserted into each of the inlet port 305 and the second outlet port 309. A second filter element 313 is provided as a filter at the second outlet port. An identical inlet filter can be provided in the inlet port 305, but may be omitted (as shown in FIG. 3).

[0281] In a subsequent step S8, the assembled first filter element 321 (from step S5) is inserted into the housing connecting portion 302 (from step S7) so that the first filter element outlet port 333 engages with the suitably provided first filter element connecting portion 335 provided by the housing connecting portion 302.

[0282] In a subsequent step S9, the housing body portion 303 is provided and joined to the assembled housing connecting portion 302. The joining between the two housing components 302 and 303 can be done by spin welding. The use of spin welding is advantageous because it does not require other materials, provides a good seal, and does not rely on chemical adhesives.

[0283] In a subsequent step S10, O-rings 305a, 307a, and 309a may be provided in grooves above the inlet port 305, first outlet port 307, and second outlet port 309, respectively. In a subsequent step (not shown), a magnet may be inserted into the magnet opening 339.

[0284] Prior to assembly, the various components are manufactured separately, for example, the housing portions 302, 303 can be formed by injection molding.

[0285] Various joining methods have been described above, including heat welding, sonic welding, and spin welding. Adhesives can be used to join some components, but are generally not preferred to minimize the risk of chemical incompatibility between the adhesive and the solvents used in the printer.

[0286] It should be noted, however, that some welding processes may result in chips and other plastic particles generated during processing becoming trapped within the filter housing 301. The filter housing 301 may typically be manufactured from polypropylene, which may itself begin to degrade and introduce additional debris after extended use. Deposits (whether generated during manufacturing or use) are preferably captured by a filter (e.g., second filter element 313) to minimize the risk that they will cause blockages elsewhere in the printer.

[0287] It will, of course, be recognized that the manufacturing and assembly methods described above are presented by way of example only. Alternative manufacturing and assembly methods may be used. Furthermore, when separate components described herein are subsequently joined together, they may be referred to as unitary components. On the other hand, when composite components are described herein, they may be provided by multiple separate components joined together by any simple method.

[0288] In the examples described above, O-rings are used to seal the various ports, however, in some alternatives, the use of an interference fit may be preferred to minimize deformation or distortion of the plastic of the filter housing and end closure.

[0289] In yet another alternative, the filter housing can be formed from stainless steel. In some embodiments, the filter size can be increased to provide an expected filter life comparable to that of the printer. Of course, such a filter may still require replacement if it becomes clogged or contaminated, for example, due to extreme operating conditions.

[0290] In an alternative arrangement, shown in FIG. 8, an alternative filter module 300′ is provided. The alternative filter module 300′ is similar in construction to the filter module 300 described above. However, instead of having external O-rings 305a, 307a, and 309a, orifices 305′, 307′, and 309′ are provided at the inlet and outlet ports, respectively, with internal O-rings 305a′, 307a′, and 309a′. A printer suitable for use with such an arrangement would include appropriately positioned protrusions 305b′, 307b′, and 309b′ suitable for engagement with the orifices 305′, 307′, and 309′. In such an arrangement, O-rings may be provided around these protrusions. The O-rings are replaced at each filter change interval.

[0291] Such an arrangement is believed to be preferable as it allows for more thorough cleaning of the arrangement at each maintenance interval, i.e., any debris trapped in the orifices of the filter module 300' will be removed when the filter module 300' is replaced.

[0292] It is further noted that the first filter element 311 engages the housing through the outlet 333 and corresponding connection 335. An O-ring 333a is provided at the interface. In alternative embodiments, the O-ring can be omitted and the filter can be assembled by interference fit or welding.

[0293] The filter module 300 can be provided with a data storage device (e.g., an RFID tag) configured to contain information regarding the filter configuration, manufacturing date, lot number, etc. The printer can interrogate such a data storage device to ensure compatibility between the filter module and the printer in which it will be installed. Alternatively, such a data storage device may be provided to enable component tracking.

[0294] In the examples described above, the second filter element 313 has been described as being located within the filter module 300. In particular, the second filter element 313 has been described as being located within the second outlet port 309. However, it will be understood that alternative arrangements are possible. For example, it is contemplated that the second filter element 313 could be eliminated entirely. Alternatively, it is contemplated that the second filter element 313 could be provided in an alternative location, such as outside the filter module 300, between the second outlet port and the venturi 73. In some alternative arrangements, the venturi pump could be eliminated entirely, with gutter suction provided by an additional pump. In such an arrangement, the second outlet port 309 could drain directly to the ink tank 317, with or without further filtration.

[0295] Additionally, the filter systems described above have been directed to user-replaceable filter modules. However, it will be appreciated that in some instances, the filter may be integrated with one or more additional components of the printer. For example, it is contemplated that the filter may be incorporated with a damper. Furthermore, it is contemplated that a filter having the general geometry described above may be incorporated into an ink tank.

[0296] 9 is a perspective view of an assembly 400 for a continuous ink jet printer. The assembly 400 includes a filter retention mechanism 402, which is described in detail below, and the filter module 300.

[0297] As its name suggests, filter retention mechanism 404 is configured to retain filter module 300. Specifically, filter retention mechanism 402 is configured to secure filter module 300 in place during use, but to removably retain filter module 300 so that it can be periodically removed for inspection and other maintenance.

[0298] The filter retention mechanism 402 includes a first support 406 and a second support 408. The second support 408 is pivotally connected to the first support 406. In other words, the second support is rotatable relative to the first support 406. The second support 408 is rotatable about a rotational axis 410. Thus, the second support 408 is rotatable relative to the first support 406 in the direction indicated by arrow 412 (e.g., about the z-axis) (however, as shown in FIG. 9 , the second support 408 is shown at one end of its rotational movement and therefore cannot rotate further in a generally clockwise direction). The second support may otherwise be described as a rotatable or removable support.

[0299] In the illustrated embodiment, the first support 406 is a fixed support. That is, the first support 406 does not rotate when the filter module 300 is removed from or inserted into the mechanism 402. Therefore, the first support 406 may alternatively be described as a fixed support. The filter retention mechanism 402 may be mounted within the entire printer through the first support 406.

[0300] In the illustrated embodiment, the first support 406 includes first and second retaining features 414, 416. However, in other embodiments, one or more of the first and second retaining features 414, 416 may otherwise form part of the second support 408. In the illustrated embodiment, the first retaining feature 414 includes a ledge on the first support 406. The ledge will be designated 414 hereinafter.

[0301] As shown in FIG. 9 , when filter retention mechanism 402 is in the locked configuration, an upper (e.g., outer) surface 418 (e.g., lid) of filter module 300 is at least partially covered by a ledge 414 of first support 406. Specifically, the underside of ledge 414 overlies the upper surface 418 of filter module 300. The ledge 414 essentially provides a boundary for travel of filter module 300, preventing filter module 300 from moving in the x-direction relative to first support 406 beyond the point where upper surface 418 contacts ledge 414, labeled 420 in FIG. 9 . In use, the pressure of fluid pumped through (e.g., into and then out of) filter module 300 urges filter module 300 in direction 420 (e.g., in the x-direction). If not held in place, filter module 300 would likely be ejected from the mechanism by the pressure of fluid pumped through the mechanism.

[0302] A difficulty in retaining filter module 300 is that top surface 418 is generally dome-shaped (i.e., at least partially arcuate). A single constraint (e.g., only a single ledge 414) could cause top surface 418 to push filter module 300 out of mechanism 402 due to interaction between top surface 418 and ledge 414. In other words, force 420 could wedger second support 408 away from first support 406, thereby urging filter module 300 to disengage itself from mechanism 402. The present invention overcomes this problem as described in more detail below.

[0303] Continuing with the description of the first support 406, in the illustrated embodiment, the first support 406 further includes a second retention feature 416, which may otherwise be described as a rotational latch. The second retention feature 416 takes the form of a clip in the illustrated embodiment. Accordingly, this clip is designated herein by the numeral 416. The clip 416 is configured to latch the mechanism 402 in the locked configuration shown in FIG. 9 . As such, the clip 416 substantially prevents rotation of the second support 408 relative to the first support 406 when engaged. In the illustrated embodiment, the clip 416 engages with a protrusion 422 (e.g., a handle) on the filter module 300, although it is contemplated that in other embodiments, the clip 416 may otherwise engage the second support 408. Similarly, while in the illustrated embodiment, the second retention feature takes the form of a clip 416, it is contemplated that in other embodiments, other rotational latch mechanisms may alternatively be used (e.g., a pivot arm).

[0304] The clip 416 includes a tapered engagement surface 424. Stated another way, the tapered engagement surface 424 is generally wedge-shaped (e.g., triangular). As shown in FIG. 9 , the thickness of the clip 416 is relatively narrower at a first end 426, which is the end that initially engages the protrusion 422 of the filter module 300 during use, than at a second end 428 of the tapered engagement surface 424. It will be appreciated that when the filter module 300 is biased into engagement with the first support 406, the protrusion 422 of the filter module 300 initially contacts the first end 426 of the clip 416. Because the thickness of the clip 416 increases toward the second end 428 (e.g., in the y-direction), the clip 416 is resiliently deformed (e.g., biased in the x-direction) by the continued progression of the protrusion 422 of the filter module 300. At the point where the protrusion 422 contacts the second end 428 of the clip 416, the clip 416 is at its maximum elastic deformation. As the protrusion 422 passes the second end 428, the protrusion 422 is received within the recess 430 of the clip 416. At the point where the protrusion 422 passes the second end 428 of the clip 416, the clip 416 returns to a relaxed configuration (e.g., substantially no elastic deformation) and receives the protrusion 422 within the recess 430. In other words, the clip 416 bounces back (e.g., in the negative x-direction). It will be appreciated from FIG. 9 that the protrusion 422, and thus the filter module 300, will remain retained by the clip 416 unless the clip 416 is again deformed to allow the second end 428 to clear (e.g., be lifted over) the protrusion 422.

[0305] For completeness, clip 416 further includes a notch 434 along a portion of its extent. The presence of notch 434 allows clip 416 to easily deform, and thus urge protrusion 422 of filter module 300 past tapered engagement surface 424 and into recess 430. In the illustrated embodiment, clip 416 is used as the second retention feature, but it will be appreciated that other retention features could alternatively be used to provide a similar rotary latch. For example, a hinged latch could alternatively be used.

[0306] Turning to the second support 408, as mentioned above, the second support 408 is pivotally connected to the first support 406. The second support 408 can therefore rotate relative to the first support 406 about a rotation axis 416 (and therefore about the z-axis) in a direction 412. In the illustrated embodiment, this rotation is enabled by a pair of shafts 434 (only one of which is visible in FIG. 9 ) that form part of the second support 408. The pair of shafts 434 extend into corresponding bores 436 (again, only one of which is visible in FIG. 9 ) that form part of the first support 406.

[0307] The second support 408 further includes a base 438 and a support member 440. A collar 441 is coupled to the support member 440. The collar 441 is configured to receive the filter module 300. The collar 441 guides the filter module 300 into position around the second support 408. The collar 441 is annular in the illustrated embodiment and can be described as a guide ring. In the illustrated embodiment, the collar 441 extends completely around the circumference of the filter module 300.

[0308] The base 438 includes a plurality of ports, in the illustrated embodiment, in the form of three female connectors: a first female connector 442, a second female connector 444, and a third female connector 446. Each of the first through third female connectors 442, 444, 446 is associated with a corresponding port extending from the filter module 300. In the illustrated embodiment, the filter module 300 includes three ports: one inlet port and two outlet ports. These ports are located on opposite ends of the top surface 418. In other embodiments, there may be more or fewer ports. Similarly, in other embodiments, the female connectors 442, 444, 446 on the base 438 may be replaced with one or more male connectors. For completeness, only the first port 448 of the first filter module 300 is labeled in FIG. 9; the second and third ports are not visible in FIG. 9.

[0309] In the illustrated embodiment, each of the three ports 448 of the filter module 300 takes the form of a male connector. As the name suggests, the female connector receives a male connector when the filter module 300 is inserted (e.g., in the negative x-direction). In other embodiments, the male connectors 448 provided on the filter module 300 can be replaced with one or more corresponding female connectors. That is, the male / female connector arrangement shown in FIG. 9 can be reversed in other embodiments (e.g., so that the filter module 300 includes the female connectors and the second support 408 includes the male connectors).

[0310] Optionally, each of the three female connectors 442, 444, 446 of the second support 408 has a different axial extent. Stated another way, each of the female connectors 442, 444, 446 can have a different axial length. This has been found to be advantageous because, upon removal of the filter module 300, the filter module 300 is more gradually disconnected from the second support 408 compared to an arrangement in which all of the female connectors 442, 444, 446 are the same length and the filter module 300 is simultaneously disconnected from all of the female connectors. As noted above, it is contemplated that this arrangement could equally be incorporated as part of the filter module 300 rather than the second support 408.

[0311] A method for inserting and retaining the filter module 300 will now be briefly described. First, the filter module 300 is initially received only by the second support 408. The second support 408 is biased away from the first support 406 to define an open volume (e.g., a filter-receiving volume) that can receive the filter module 300. Next, the filter module 300 is received by the second support 408 such that the ports 448 of the filter module 300 are received by the corresponding female connectors 442, 444, 446 of the second support 408. Furthermore, the support member 440 also guides the filter module 300 into the correct position by abutting against the filter module 300. Next, the combination of the filter module 300 and the second support 408 is biased toward the first support 406 by rotation about the rotation axis 410 (e.g., in direction 412 and about the z-axis). As the second support 408 and filter module 300 are urged toward the first support 406, the shelf 414 of the first support 406 gradually overlaps (e.g., covers) an increasingly greater extent of the top surface 418 of the filter module 300. In other words, an increasingly larger area of ​​the top surface 418 of the filter module 300 is covered by the shelf 414. At the same time, the protrusion 422 of the filter module 300 initially contacts the first end 428 of the tapered engagement surface 424 of the clip 416. The protrusion 422 urges the clip 416 away from the top surface 418 (e.g., in the x-direction) by increasing the thickness of the clip 416 along the tapered engagement surface 424, elastically deforming the clip 416. When the protrusion 422 extends beyond the second end 428 of the tapered engagement surface 424, the protrusion 422 is received by the recess 430. As shown in FIG. 9, this shows a locked configuration in which the filter module 300 is held by the filter retention mechanism 402.

[0312] The present invention advantageously provides a retention mechanism that easily retains filter module 300 during operation, while also providing a low-pressure release mechanism that allows filter module 300 to be removed later when maintenance or service is required. As briefly noted above, during operation, filter module 300 is urged in direction 420 (e.g., in the x-direction) by relatively high-pressure fluid flow through the filter (through ports and connectors 442, 444, 446, 448). Therefore, filter module 300 must be retained to prevent it from being ejected by the fluid pressure. A challenge faced is the need to securely retain filter module 300 while occasionally removing it to replace the filter for routine service. The present invention overcomes these problems by essentially providing a two-stage retention mechanism via ledge 414 and clip 416.

[0313] The ledge 414 provides at least a detent function to facilitate generally axial retention (e.g., preventing the filter module 300 from being ejected in direction 420 and / or the x-direction), and in some embodiments may abut the top surface 418. The ledge 414 may be described as preventing the filter module 300 from moving to the point where it is disengaged from the multiple ports in the second support 408. As discussed above, the generally arcuate top surface 418 of the filter module 300 also presents a problem by biasing or moving the filter module 300 away from the first support 406 in a direction that could potentially result in the filter module 300 being ejected or separated from the first support 406. This problem is due to the interaction between the dome-shaped top surface 418 and the flat ledge 414. The inventors have discovered that incorporating a single retention feature (e.g., like the ledge 414) does not provide sufficient retention of the filter module 300 during actuation. By advantageously incorporating a second retention feature (e.g., in the form of clip 416), filter module 300 is substantially secured in place and upper surface 418 is substantially prevented from biasing filter module 300 away from first support 406 (by second retention feature rotationally latching second support 408 relative to first support 406).

[0314] Additionally, clip 416 attempts to substantially rotationally latch first support 406 and second support 408 together in a direction different from the biasing direction 420 to which filter module 300 is biased upon activation. Thus, clip 416 can be easily disengaged by an operator, allowing second support 408 and filter module 300 to pivot away from first support 406 and easily remove filter module 300 from filter retention mechanism 402. Thus, advantageously, the present invention allows for generally axial retention of filter module 300 by ledge 414 (e.g., in the negative x-direction), yet also allows for a rotational latch in a different direction (e.g., about the x-axis) that can be easily released when needed to secure first support 406 and second support 408 together and provide access to filter module 300.

[0315] Yet another advantage is that the tapered engagement surface 424 of the clip 416 allows the clip 416 to substantially automatically engage with the protrusion 422 of the filter module 300 when the filter module 300 (and second support 408) is rotated to the position shown in Figure 9. Thus, the clip 416 latches the retention mechanism 402 in the locked configuration when the mechanism transitions from the unlocked configuration to the locked configuration shown in Figure 9. That is, the clip 416 latches the mechanism 402 in the locked configuration when the second support 408 is biased or rotated toward the first support 406. Thus, the retention direction of the clip 416 is substantially perpendicular to the direction 420 in which the filter module 300 is biased during use.

[0316] Optionally, the retention mechanism 402 further includes a release mechanism (not visible in FIG. 9 ) for releasing the filter module 300 from the filter retention mechanism 402 (e.g., in the x-direction). It will be appreciated that in use, the filter module 300 may be connected to the second support 408 and become somewhat stuck. The release mechanism aids in the removal of the filter module 300, for example, after extended use. The release mechanism may take the form of a lever that mechanically increases the force applied by an operator to remove the filter module 300. Alternatively, a screw arrangement may be used that biases the filter module 300 away from the second support 408. It will be appreciated that various other release mechanisms may alternatively be used. The release mechanism may be described as a filter release mechanism. The release mechanism may reduce the force required by the operator (to release or remove the filter) to around 70 N.

[0317] Turning to Figure 10, there is shown a cross-sectional side view of the assembly 400 shown in Figure 9. Many of the features shown in Figure 10 have already been described with respect to Figure 9, and therefore, for the sake of brevity, that description will not be repeated here.

[0318] FIG. 10 illustrates filter module 300 having a third port 452 that is received by third female connector 446 of second support 408. FIG. 10 also illustrates various features of first support 406, including ledge 414 and clip 416 (including notch 432). FIG. 10 illustrates a small gap (e.g., clearance) 419 between top surface 418 of filter module 300 and ledge 414. Gap 419 provides clearance when filter 300 and second support 408 are rotated relative to first support 406 into the locked configuration shown in FIG. 10. In use, filter module 300 is urged outward by pressurized fluid flowing therethrough, thereby urging it into engagement with ledge 414.

[0319] 10 also illustrates the relative alignment of the protrusion 422 of the filter module 300 with the recess 430 of the clip 416. The arcuate nature of the top surface 418 of the filter module 300 is also shown. The alignment feature 456 of the first body 406 is also shown. When the retention mechanism 402 is in the locked configuration, the protrusion 422 of the filter module 300 is positioned between the alignment body 456 and the second end 428 of the tapered engagement surface 424.

[0320] Also shown is an opening 454 in the first support 406 through which a portion of the filter module 300 is partially received in the area labeled 458 .

[0321] 10 also illustrates collar 441 including cutout 443. Cutout 443 allows for providing the magnet of filter module 300 in close proximity to the sensor, as will be described in more detail below with respect to FIG.

[0322] Turning to Figure 11, a rear view of the assembly 400 shown in Figures 9 and 10 is shown. This rear view shows the first support 406 in more detail. For example, the opening 454 in the first support 406 is shown.

[0323] FIG. 11 shows that the retention mechanism 402 includes a sensor 460, which in the illustrated embodiment is a magnetic sensor (e.g., a Hall Effect sensor). The sensor 460 is used to detect at least that the filter module 300 is properly seated in the locked configuration shown in FIG. 11 . Stated another way, the sensor 460 determines not only that the filter module 300 is properly positioned relative to the second support 408, but also that the second support 408 is in the correct locked configuration relative to the first support 406. The sensor 460 also determines that the filter module 300 is present. The sensor 460 can detect the presence of a magnet provided on the filter module 300. The sensor 460 has an advantage over alternative detection mechanisms because it can detect the presence of the filter module 300 in addition to detecting the position of the second support 408 relative to the first support 406.

[0324] 12 is a perspective view of assembly 400', which corresponds to assembly 400 shown in the prior figures, except for some minor differences (described below).

[0325] 12, the assembly 400' is shown in an unlocked configuration, such that the filter module 300' can be received by the second support 408 in the illustrated position. The second support 408 is shown rotated about a rotation axis 410 away from the first support 406'.

[0326] Filter module 300' differs from filter module 300 in that its protrusion 422' includes openings 423', 425'. Openings 423', 425' provide openings through which an operator can grasp and manipulate filter module 300'.

[0327] Unlike the first support 406, the first support 406' shown in FIG.

[0328] Figure 13 is a perspective view of the filter module retention mechanism 402' in an unlocked configuration. Figure 13 shows the assembly 400' of Figure 12 without the filter module 300'.

[0329] 13 illustrates a second support 408 including a collar 441 coupled to a support member 440. The second support 408 further includes first through third female connectors 442, 444, 446. The first through third female connectors 442, 444, 446 are associated with a corresponding one of the ports extending from the filter module.

[0330] As used herein, the term retaining includes active engagement (e.g., abutment) and retention using (for example) detents / buffers that prevent movement of a component (e.g., a filter module) past the retention feature. Thus, retention does not require, but can include, active contact.

[0331] The top surface of the filter module may alternatively be described as the exterior surface. The top surface of the filter module may alternatively be described as the surface of the filter module opposite one or more ports (e.g., connectors) of the filter module.

[0332] Various modifications and variations can be made to the above-described embodiments. For example, while the filter modules described above have been described in the context of a continuous inkjet printer, these modules could be provided separately. Such filter modules could be provided as removable modules in an inkjet printer. While particular forms of ink systems and continuous inkjet printers have been described, it will be further appreciated that the above-described filters can be applied to a variety of printer configurations. For example, it is contemplated that the above-described filters could be used in systems using non-pigmented inks or soft pigmented inks. Similarly, while an electrostatic deflection arrangement using two deflection electrodes to deflect a single ink droplet jet has been described, different forms of deflection, using, for example, a different number of deflection electrodes and / or a different number of droplet streams, may be preferred. Similarly, it is contemplated that the filters could be used in printers that do not require continuous ink jets to be generated.

[0333] The above examples are intended to be illustrative in nature and are not intended to limit or define the scope of protection, which is defined by the claims.

[0334] The following examples are provided in addition to or instead of the above. Features described in any of the following examples may be utilized in any of the other examples described herein.

[0335] Example 1: A filter module for filtering ink, the filter module including: a filter housing defining a filter chamber, an inlet port, a first outlet port, and a second outlet port; and a first filter element including a first filter media disposed in the filter chamber, the filter housing configured to define a first filtrate pathway from the inlet port through the first filter element to the first outlet port and a second pathway from the first inlet port across an outer surface of the first filter element to the second outlet port, wherein, in use, the first outlet port and the second outlet port are located vertically above the inlet port.

[0336] Example 2 : The filter module according to Example 1 further including a second filter element including a second filter media disposed in the filter housing, wherein the second pathway is a second filtrate pathway from the inlet port through the second filter media to the second outlet port.

[0337] Example 3 : A filter module according to Example 2, wherein the first filter element has a first absolute rating and the second filter element has a second absolute rating different from the first absolute rating.

[0338] Example 4 : A filter module according to any preceding example, wherein the filter housing is configured to define a third filtrate path from the inlet port through the first filter media to the second outlet port.

[0339] Example 5 : A filter module according to Example 4, in which the third filtrate path passes through the first filter element a first time to a central cavity surrounded by the first filter element, and then passes through the first filter element a second time to an outer cavity surrounding the first filter element.

[0340] Example 6 A filter module according to any preceding example, wherein, in use, the filter is arranged to permit ink to flow in a generally upward direction from the inlet port to the first and second outlet ports.

[0341] Example 7 : A filter module according to any preceding example, wherein in use the second outlet port is located vertically above the first outlet port.

[0342] Example 8 : A filter module according to any preceding example, wherein, in use, the ink stream along the first filtrate path is in a direction generally opposite to the direction in which gravity acts, and / or the ink stream along the second path is in a direction generally opposite to the direction in which gravity acts.

[0343] Example 9 The filter module according to any preceding example, wherein the second passageway includes a passageway defined between an outer surface of the first filter element and a wall of the filter housing that defines the chamber.

[0344] Example 10 : The filter module according to Example 3 or any preceding example dependent thereon, wherein the absolute rating of the second filter medium is greater than the absolute rating of the first filter element.

[0345] Example 11 : The filter module according to Example 3 or any preceding example dependent thereon, wherein the effective surface area of ​​the first filter element is greater than the effective surface area of ​​the second filter element.

[0346] Example 12 : A filter module according to any preceding example, wherein the first filter media is a pleated filter media.

[0347] Example 13 : A filter module according to Example 12, wherein the first filter media includes a pleated protection filter at least partially covering the pleated filter media.

[0348] Example 14 : The filter module according to example 12 or example 13, wherein the first filter element includes an injection screen disposed between the pleated filter media and the first injection port.

[0349] Example 15 : A filter module according to example 14, in which the absolute rating of the first filter element is determined by the exit screen.

[0350] Example 16 : A filter module according to any preceding example, wherein the first filter element defines a central cavity, the first filter element including a central support structure disposed within the central cavity.

[0351] Example 17 : A filter module according to Example 11 or any preceding example dependent thereon, wherein the nominal rating of the first filter element is determined by a pleated filter media.

[0352] Example 18 : A filter module according to any preceding example, wherein the first filter element is generally cylindrical.

[0353] Example 19 : A filter module according to any preceding example, wherein the inlet port, the first outlet port, and the second outlet port are disposed on a single face of the filter housing.

[0354] Example 20 : A filter module according to any preceding example, wherein, in use, the flow rate of ink through the second outlet port is greater than the flow rate of ink through the first outlet port.

[0355] Example 21 A filter module according to any preceding example, further comprising: a presence detection feature configured to interact with a detector configured to detect when the filter is engaged with the printing system.

[0356] Example 22 : A filter module according to any preceding example, further comprising a removal handle.

[0357] Example 23A filter module according to any preceding example, further comprising: an engagement structure for engagement with a complementary structure of the printer to secure the filter module in an installed configuration.

[0358] Example 24 : A continuous ink jet printer comprising an ink circuit including an ink tank, an ink pump arrangement, and a filter module for filtering ink according to any of the preceding examples, wherein the ink pump is configured to pump ink from the ink tank through a first inlet port and along at least one of a first filtrate path and a second path.

[0359] Example 25 25. A continuous ink jet printer according to example 24, wherein in use the filter module is positioned to pump ink in a generally upward direction away from the inlet port.

[0360] Example 26 26. The continuous ink jet printer according to Example 24 or Example 25, further comprising a pressure sensor configured to sense a pressure drop across the first filter element.

[0361] Example 27 27. A continuous ink jet printer according to any one of Examples 24 to 26 dependent on at least Example 2, further comprising a pressure sensor configured to sense a pressure drop across the second filter element.

[0362] Example 28: A filter housing for a filter module for filtering ink, the filter housing defining a filter chamber, an inlet port, a first outlet port, and a second outlet port, the filter chamber configured to receive a first filter element, the filter housing configured to define a first filtrate pathway from the inlet port through the received first filter element to the first outlet port and a second pathway from the first inlet port across an outer surface of the received first filter element to the second outlet port, the filter housing wherein, in use, the first outlet port and the second outlet port are located vertically above the inlet port.

[0363] Example 29 : A method of manufacturing a filter module for filtering ink according to any one of Examples 1 to 23, comprising: placing a second filter element including a second filter media having a second absolute rating in a second outlet port defined by a filter housing further defining an inlet port, a first outlet port, and a filter chamber; and placing a first filter element including a first filter media having a first absolute rating in the filter chamber.

[0364] Example 30 The method according to Example 29, further comprising forming a first filter element, the forming step comprising forming a pleated filter media having a central cavity, securing a first closure over a first end of the filter media, and securing a second closure over a second end of the filter media opposite the first end.

[0365] Example 31 : The method according to Example 30, wherein the method includes, before securing the first and second closures, placing a central support structure in the central cavity and surrounding the outer surface of the pleated filter media with a pleated protective filter.

[0366] Example 32 32. The method according to Example 31, further comprising the step of: heat welding the first closure and the second closure to the pleated filter media.

[0367] Example 33 ;A method according to any one of Examples 30 to 32, wherein the first filter element includes an outlet port engagement arrangement, and wherein the step of placing the first filter element in the main chamber includes a step of engaging the engagement arrangement to the first outlet port, and / or the method further includes a step of joining the two parts of the filter housing by spin welding after placing the first filter element in the filter chamber.

[0368] Example 34 A method of filtering ink, comprising: pumping ink through an inlet port into a filter chamber defined by a filter housing; filtering a first portion of the ink flowing along a first filtrate path with a first filter element disposed in the filter chamber, the filtrate flowing from the filter chamber through a first outlet port; and flowing a second portion of the ink along a second path passing across an outer surface of the first filter element to a second outlet port, the method comprising: a) filtering ink along the first filtrate path and the second path;

[0369] Example 35 35. The method according to example 34, further comprising filtering a second portion of the ink through a second filter.

[0370] Example 36 The method according to Example 35, wherein the step of flowing the second portion of the ink along the second path includes filtering the second portion of the ink through a second filter disposed in the second outlet port.

[0371] Example 37 The method according to Example 35 or Example 36, wherein the filtering step with the first filter element includes filtering a first portion of the ink to remove particles larger than a first predetermined size, and the filtering step with the second filter element includes filtering a second portion of the ink to remove particles larger than a second predetermined size that is larger than the first predetermined size.

[0372] Example 38 38. A method of operating a continuous ink jet printer comprising the method of filtering ink according to any one of Examples 34 to 37, further comprising pumping a first portion of the ink from a first outlet port to a print head of the continuous ink jet printer.

[0373] Example 39 39. The method of operating the continuous ink jet printer of Example 38, further comprising the step of: pumping a second portion of the ink from the second outlet port to the venturi pump.

[0374] Example 40 39. A method of operating a continuous ink jet printer according to Example 38 or Example 39, further comprising the step of pumping a second portion of the ink from the second outlet port to an ink tank of the continuous ink jet printer.

[0375] Example 41 : A filter module retention mechanism for holding a filter module for a continuous inkjet printer, comprising: a first support; and a second support pivotally connected to the first support, wherein the filter module is receivable by at least one of the first and second supports in an unlocked configuration in which the second support is spaced apart from the first support, at least one of the first and second supports comprising a first retention feature configured to hold the filter module in a locked configuration in which the second support is close to the first support to retain the filter module, and at least one of the first and second supports comprising a second retention feature configured to latch the mechanism in the locked configuration to prevent rotation of the second support relative to the first support.

[0376] Example 42 : The filter module retention mechanism of Example 41, wherein the second retention feature is a clip.

[0377] Example 43 : The filter module retention mechanism of Example 42, wherein the clip includes a tapered engagement surface.

[0378] Example 44 44. The filter module retention mechanism of any of Examples 41 to 43, wherein the second retention feature latches the mechanism in the locked configuration when the filter module retention mechanism transitions from the unlocked configuration to the locked configuration.

[0379] Example 45 : The filter module retention mechanism of Example 44, wherein the second retention feature latches the mechanism into a locked configuration when the second support is rotated toward the first support.

[0380] Example 46 : The filter module retention mechanism of any of Examples 41 to 45, wherein the first retention feature includes a shelf portion of the first support.

[0381] Example 47 : A filter module retention mechanism of any of Examples 41 to 46, wherein at least one of the first and second supports capable of receiving a filter module further includes a plurality of ports for connection to corresponding ports of the filter module.

[0382] Example 48 : The filter module retention mechanism of Example 47, wherein the plurality of ports includes a plurality of female connectors.

[0383] Example 49 :A filter module retention mechanism of any of Examples 41 to 48, wherein, in use, the retention force exerted by the first retention feature is in a first direction and the retention force exerted by the second retention feature is in a second direction different from the first direction.

[0384] Example 50 :A filter module retention mechanism of any of Examples 41 to 49, wherein the filter module is receivable by one of the first and second supports in an unlocked configuration, and the other of the first and second supports includes a sensor configured to detect the filter module in at least a locked configuration.

[0385] Example 5151. The filter module retention mechanism of any one of Examples 41 to 50, further comprising a release mechanism for releasing the filter module from the filter module retention mechanism.

[0386] Example 52 :A filter module retention mechanism of any of Examples 41 to 51, wherein the second support is configured to receive the filter module in an unlocked configuration and the first support is a fixed support configured to retain the filter module in a locked configuration.

[0387] Example 53 : The filter module retention mechanism of Example 52, wherein the first support includes a second retention feature.

[0388] Example 54 :An assembly for a continuous ink jet printer, comprising a filter module retention mechanism according to any of Examples 41 to 53 and a filter module retained by the filter module retention mechanism.

[0389] Example 55 : The assembly of Example 54, wherein the second retention feature engages the protrusion of the filter module in a locked configuration.

[0390] Example 56 : A continuous ink jet printer including the assembly of Example 54 or Example 55.

[0391] Example 57 : The continuous ink jet printer of Example 56, wherein the filter module is a filter module according to any one of Examples 1 to 23.

[0392] Example 58A method for securing a filter module within a filter module retention mechanism of a continuous ink jet printer, the method comprising: biasing the filter module retention mechanism into an unlocked configuration in which a second support is spaced from the first support; placing the filter module in engagement with one of the first and second supports so that the filter module is received by one of the first and second supports; and biasing the mechanism into the locked configuration by rotating the second support toward the first support to retain the filter module with a first retention feature of one of the first and second supports and engaging a second retention feature of one of the first and second supports so that the second support latches the filter module retention mechanism in a locked configuration close to the first support, thereby substantially preventing rotation of the second support relative to the first support.

[0393] Example 59 The method of Example 56, wherein placing the filter module in engagement with one of the first and second supports includes placing the filter module in engagement with the second support, and biasing the filter module retention mechanism into the locking configuration includes aligning a first retention feature of the first support with the filter module to retain the filter module, and biasing a second retention feature of the first support into the engagement state to latch the mechanism in the locking configuration.

[0394] Example 60 : The method of example 58 or example 59, wherein the second retention feature engages the filter module.

[0395] Example 61 : The method of Example 60, wherein the second retention feature engages a protrusion on the filter module.

[0396] Example 62 : The method of Example 61, wherein the step of engaging the protrusion of the filter module with the second retention feature includes the step of biasing a tapered engagement surface of the clip over the protrusion of the filter module to latch the mechanism in the locked configuration.

[0397] Example 63 63. The method of any one of Examples 58 to 62, further comprising detecting, via a sensor, that the filter module is properly seated in at least the locked configuration.

Claims

1. A filter module for filtering ink, comprising: A filter housing, filter chamber, Inlet port, a first outlet port; and a second outlet port; a filter housing defining a first filter element disposed in the filter chamber and including a first filter media; Including, the filter housing is configured to define a first filtrate path from the inlet port through the first filter element to the first outlet port and a second filtrate path from the first inlet port across an exterior surface of the first filter element to the second outlet port; the inlet port, the first outlet port, and the second outlet port are located on a single face of the filter housing; In use, the first outlet port and the second outlet port are positioned vertically above the inlet port. Filter module.

2. A filter module for filtering ink, comprising: A filter housing, filter chamber, Inlet port, a first outlet port; and a second outlet port; a filter housing defining a first filter element including a first filter media disposed in the filter chamber and a second filter element including a second filter media disposed in the filter housing; Including, the filter housing is configured to define a first filtrate path from the inlet port through the first filter element to the first outlet port and a second filtrate path from the first inlet port across an exterior surface of the first filter element to the second outlet port; the second path is a second filtrate path from the inlet port through the second filter media to the second outlet port; In use, the first outlet port and the second outlet port are positioned vertically above the inlet port. Filter module.

3. A filter module for filtering ink, comprising: A filter housing, filter chamber, Inlet port, a first outlet port; and a second outlet port; a filter housing defining a first filter element disposed in the filter chamber, the first filter element including a first pleated filter media, the first filter element further including an injection screen disposed between the pleated filter media and the first injection port; Including, the filter housing is configured to define a first filtrate path from the inlet port through the first filter element to the first outlet port and a second filtrate path from the first inlet port across an exterior surface of the first filter element to the second outlet port; In use, the first outlet port and the second outlet port are positioned vertically above the inlet port. Filter module.

4. A filter module for filtering ink, comprising: A filter housing, filter chamber, Inlet port, a first outlet port; and a second outlet port; a filter housing defining a first generally cylindrical filter element including a first filter medium disposed in the filter chamber; Including, the filter housing is configured to define a first filtrate path from the inlet port through the first filter element to the first outlet port and a second filtrate path from the first inlet port across an exterior surface of the first filter element to the second outlet port; In use, the first outlet port and the second outlet port are positioned vertically above the inlet port. Filter module.

5. 5. The filter module of claim 2, wherein the inlet port, the first outlet port, and the second outlet port are located on a single face of the filter housing.

6. a second filter element including a second filter media disposed in the filter housing; the second path is a second filtrate path from the inlet port through the second filter media to the second outlet port; 5. The filter module of claim 1, claim 3, or claim 4.

7. 5. The filter module of claim 1, claim 2, or claim 4, wherein the first filter media is a pleated filter media, and the first filter element includes an injection screen disposed between the pleated filter media and the first injection port.

8. 4. The filter module of claim 1, wherein the first filter element is generally cylindrical.

9. 7. The filter module of claim 2 or claim 6, wherein the first filter element has a first absolute rating and the second filter element has a second absolute rating that is different from the first absolute rating.

10. 10. The filter module of claim 1, wherein the filter housing is configured to define a third filtrate path from the inlet port through the first filter media to the second outlet port.

11. 11. The filter module of claim 10, wherein the third filtrate path passes through the first filter element a first time to a central cavity surrounded by the first filter element and then passes through the first filter element a second time to an outer cavity surrounding the first filter element.

12. 12. A filter module according to any preceding claim, wherein, in use, the filter is arranged to allow ink to flow in a generally upward direction from the inlet to the first and second outlet ports.

13. 13. A filter module according to any preceding claim, wherein, in use, the second outlet port is located vertically above the first outlet port.

14. When using, the flow of ink along the first filtrate path is in a direction substantially opposite to the direction of gravity; and / or the flow of ink along the second path is in a direction substantially opposite to the direction of gravity; A filter module according to any one of claims 1 to 13.

15. 15. The filter module of claim 1, wherein the second passage comprises a passage defined between an outer surface of the first filter element and a wall of the filter housing that defines the chamber.

16. 16. The filter module of claim 9 or any one of claims 10 to 15 depending thereon, wherein the absolute rating of the second filter media is greater than the absolute rating of the first filter element.

17. 17. A filter module according to claim 9 or any one of claims 10 to 16 depending thereon, wherein the effective surface area of ​​the first filter element is greater than the effective surface area of ​​the second filter element.

18. 8. The filter module of claim 3 or claim 7, wherein the first filter element includes a pleated protective filter at least partially covering the pleated filter media.

19. 8. The filter module of claim 3 or claim 7, wherein the absolute rating of the first filter element is determined by the exit screen.

20. 20. The filter module of any one of claims 1-19, wherein the first filter element defines a central cavity, the first filter element including a central support structure disposed within the central cavity.

21. 21. A filter module according to claim 17 or any one of claims 18 to 20 depending thereon, wherein the nominal rating of the first filter element is determined by the pleated filter media.

22. 22. The filter module of claim 1, further comprising a presence detection feature configured to interact with a detector configured to detect when the filter is engaged with a printing system.

23. 23. The filter module of any one of claims 1 to 22, further comprising a removal handle.

24. 24. A filter module according to any preceding claim, further comprising an engagement structure for engagement with a complementary structure on a printer to secure the filter module in an installed configuration.

25. 1. A continuous ink jet printer, comprising: an ink circuit comprising an ink tank, an ink pump arrangement and a filter module for filtering the ink according to any one of claims 1 to 24; Including, the ink pump is configured to pump ink from the ink tank through the first inlet port and along at least one of the first filtrate path and the second path; Continuous inkjet printer.

26. 26. A continuous ink jet printer according to claim 25, wherein, in use, the filter module is arranged to pump ink in a generally upward direction away from the inlet port.

27. 27. A continuous ink jet printer according to claim 25 or claim 26, further comprising a pressure sensor configured to sense a pressure drop across the first filter element.

28. 28. A continuous ink jet printer according to any one of claims 25 to 27 when dependent on at least claim 2 or claim 6, further comprising a pressure sensor configured to sense a pressure drop across the second filter element.

29. 1. A filter housing for a filter module for filtering ink, comprising: The filter housing includes: a filter chamber; an inlet port; a first outlet port; a second outlet port; and and the filter chamber is configured to receive a first filter element; the filter housing is configured to define a first filtrate path from the inlet port to the first outlet port through the received first filter element and a second filtrate path from the first inlet port to the second outlet port across an exterior surface of the received first filter element; In use, the first outlet port and the second outlet port are positioned vertically above the inlet port. Filter housing.

30. 25. A method of manufacturing a filter module for filtering ink according to any one of claims 1 to 24, comprising the steps of: placing a second filter element including a second filter media having a second absolute rating in a second outlet port defined by a filter housing further defining an inlet port, a first outlet port, and a filter chamber; placing a first filter element in the filter chamber, the first filter element including a first filter media having a first absolute rating; A method comprising:

31. forming a pleated filter media having a central cavity; securing a first closure over a first end of the filter media; securing a second closure over a second end of the filter media opposite the first end; forming the first filter element comprising:

31. The method of claim 30 further comprising:

32. Prior to securing the first and second closures together: The method comprises: placing a central support structure in the central cavity; surrounding an outer surface of the pleated filter media with a pleat protection filter; Including, 32. The method of claim 31 .

33. 33. The method of claim 32, further comprising heat welding the first closure and the second closure to the pleated filter media.

34. the first filter element includes an outlet port engagement arrangement, and placing the first filter element in the main chamber includes engaging the engagement arrangement with the first outlet port; and / or the method further comprising joining the two parts of the filter housing together by spin welding after placing the first filter element in the filter chamber.

34. The method of any one of claims 31 to 33.

35. 1. A method for filtering ink, comprising: pumping ink through an inlet port into a filter chamber defined by a filter housing; filtering a first portion of the ink flowing along a first filtrate path, the filtrate exiting the filter chamber through a first outlet port, with a first filter element disposed in the filter chamber; flowing a second portion of the ink along a second path across an exterior surface of the first filter element and passing to a second outlet port; Including, a flow direction of the ink when flowing along the first filtrate path and the second path includes a component in a direction opposite to gravity; method.

36. 36. The method of claim 35, further comprising filtering the second portion of the ink through a second filter.

37. 37. The method of claim 36, wherein flowing the second portion of the ink along the second path includes filtering by the second filter disposed in the second outlet port.

38. filtering with the first filter element includes filtering the first portion of ink to remove particles above a first predetermined size; filtering with the second filter element includes filtering the second portion of ink to remove particles above a second predetermined size that is larger than the first predetermined size; 38. The method of claim 36 or claim 37.

39. 1. A method of operating a continuous ink jet printer, comprising:

39. The method of filtering ink according to any one of claims 35 to 38, further comprising pumping the first portion of the ink from the first outlet port to a printhead of the continuous ink jet printer. method.

40. 40. A method of operating a continuous ink jet printer according to claim 39, further comprising pumping said second portion of said ink from said second outlet port to a venturi pump.

41. 41. A method of operating a continuous ink jet printer according to claim 39 or claim 40, further comprising pumping said second portion of said ink from said second outlet port to an ink tank of said continuous ink jet printer.

42. 1. A filter module retention mechanism for retaining a filter module for a continuous ink jet printer, comprising: a first support; a second support pivotally connected to the first support; Including, the filter module is receivable by at least one of the first and second supports in an unlocked configuration in which the second support is distal to the first support; at least one of the first and second supports includes a first retention feature configured to hold the filter module in a locked configuration in which the second support is adjacent to the first support to retain the filter module; at least one of the first and second supports includes a second retention feature configured to latch the mechanism in the locking configuration to substantially prevent rotation of the second support relative to the first support; Filter module retention mechanism.

43. 43. The filter module retention mechanism of claim 42, wherein the second retention feature is a clip.

44. 44. The filter module retention mechanism of claim 43, wherein the clip includes a tapered engagement surface.

45. 45. The filter module retention mechanism of any one of claims 42 to 44, wherein the second retention feature latches the mechanism in the locked configuration when the mechanism transitions from the unlocked configuration to the locked configuration.

46. 46. ​​The filter module retention mechanism of claim 45, wherein the second retention feature latches the mechanism into the locked configuration when the second support is rotated toward the first support.

47. 47. A filter module retention mechanism according to any one of claims 42 to 46, wherein the first retention feature comprises a ledge on the first support.

48. the at least one of the first and second supports capable of receiving the filter module further includes a plurality of ports for connection to corresponding ports of the filter module; Optionally, the plurality of ports comprises a plurality of female connectors; 48. A filter module retention mechanism according to any one of claims 42 to 47.

49. in use, a retention force exerted by the first retention feature is in a first direction; a retention force exerted by the second retention feature is in a second direction different from the first direction; 49. A filter module retention mechanism according to any one of claims 42 to 48.

50. the filter module is receivable by one of the first and second supports in the unlocked configuration; the other of the first and second supports includes a sensor configured to detect the filter module in at least the locked configuration.

50. A filter module retention mechanism according to any one of claims 42 to 49.

51. 51. A filter module retention mechanism according to any one of claims 42 to 50, further comprising a release mechanism for releasing the filter module from the filter module retention mechanism.

52. the second support is configured to receive the filter module in an unlocked configuration; the first support is a fixed support configured to hold the filter module in a locked configuration; 52. A filter module retention mechanism according to any one of claims 42 to 51.

53. 53. The filter module retention mechanism of claim 52, wherein the first support includes the second retention feature.

54. 1. An assembly for a continuous ink jet printer, comprising: The filter module retention mechanism of any one of claims 42 to 53; a filter module held by the filter module holding mechanism; The assembly containing:

55. 55. The assembly of claim 54, wherein the second retention feature engages a protrusion on the filter module in the locked configuration.

56. 56. The assembly of claim 54 or claim 55. Continuous inkjet printers, including:

57. 57. A continuous ink jet printer according to claim 56, wherein the filter module is a filter module according to any one of claims 1 to 24.

58. 1. A method for securing a filter module to a filter module retention mechanism of a continuous ink jet printer, comprising: biasing the filter module retention mechanism into an unlocked configuration in which the second support is distal to the first support; placing the filter module in engagement with one of the first and second supports such that the filter module is received by the one of the first and second supports; biasing the filter module retention mechanism into a locked configuration in which the second support is adjacent to the first support by rotating the second support toward the first support, retaining the filter module with a first retention feature of one of the first and second supports, and engaging a second retention feature of one of the first and second supports to latch the mechanism in the locked configuration and substantially prevent rotation of the second support relative to the first support; A method comprising:

59. placing the filter module in engagement with one of the first and second supports includes placing the filter module in engagement with the second support; biasing the filter module retention mechanism into the locked configuration includes aligning the first retention feature of the first support with the filter module to retain the filter module, and biasing the second retention feature of the first support into an engaged state to latch the mechanism into the locked configuration.

57. The method of claim 56.

60. 60. The method of claim 58 or claim 59, wherein the second retention feature engages the filter module.

61. 61. The method of claim 60, wherein the second retention feature engages a protrusion on the filter module.

62. 62. The method of claim 61, wherein engaging the protrusion of the filter module with the second retention feature includes biasing a tapered engagement surface of a clip over the protrusion of the filter module to latch the mechanism into the locking configuration.

63. 63. The method of any one of claims 58 to 62, further comprising detecting via a sensor that the filter module is properly seated in at least the locking arrangement.

Images