Filter for ink

Abstract

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 also 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 via 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 disposed vertically above the inlet port.

Description

Technical Field

[0001] The present invention relates to inkjet printing, and more particularly to an ink filter for filtering ink. The ink filter can be used for pigment-based ink in an inkjet printer such as a continuous inkjet printer. Background Art

[0002] In an inkjet printing system, printing consists of individual drops of ink generated at a nozzle and ejected toward a substrate. There are two main systems: on-demand printing, in which ink drops are generated as and when needed for printing, and continuous inkjet printing, in which droplets are generated continuously and only selected droplets are directed toward a substrate, with the remainder being recycled to the ink supply.

[0003] A continuous inkjet printer supplies pressurized ink to a printhead droplet generator, where a continuous jet or stream of ink ejected from a nozzle is stimulated, for example, by an oscillating piezoelectric element to form individual regular drops of ink. The drops are directed past a charging electrode where they are selectively and individually imparted with a predetermined charge before passing through a transverse electric field, which may be arranged across a pair of deflection plates. Each charged droplet is deflected by the electric field before impacting the substrate, the amount of deflection depending on the amount of its charge, while uncharged drops continue undeflected and are collected in a gutter, from which they are recycled to the ink supply for reuse. The charged drops bypass the gutter and impact the substrate at a position determined by the charge on the droplet and the position of the substrate relative to the printhead. Typically, the substrate moves in one direction relative to the printhead, and the printhead is deflected in a direction generally perpendicular to that direction, although the deflection plates may be oriented in a manner inclined from the perpendicular to compensate for the velocity of the substrate (the movement of the substrate relative to the printhead between droplet arrivals means that the droplet line would not otherwise extend completely perpendicular to the direction of movement of the substrate).

[0004] In continuous inkjet printing, characters can be printed from a matrix containing a regular array of potential drop locations. Each matrix contains a number of columns (strokes), each of which is defined by a line containing a number of potential drop locations (e.g., seven), which are determined by the charge applied to the drop and various other influencing factors. Thus, each available drop is charged according to its expected position in the stroke. If a particular drop is not used, the drop is not charged, but rather captured at the gutter for recirculation. This cycle is repeated for all strokes in the matrix and then restarts for the next character matrix.

[0005] Ink is delivered to the printhead under pressure by an ink supply system, which is generally contained within a sealed compartment of a cabinet that includes separate compartments for control circuitry and a user interface panel. The system includes a main pump that draws ink from an ink storage tank of the ink supply system via a filter and delivers it under pressure to the printhead. As the ink is consumed, the tank is refilled as needed from a replaceable ink cartridge that is releasably connected to the tank via a supply conduit. Ink is supplied from the tank to the printhead via a flexible delivery conduit. Unused ink drops captured by the gutter are recirculated to the tank via a return conduit by a pump. The flow of ink in each of the conduits is generally controlled by a solenoid valve and / or other similar components.

[0006] Reliable droplet generation (by jet breakup) depends on the ink having substantially non-viscous properties, so the ink in the ink tank is preferably dilute. Ink recirculated from the gutter is depleted of solvent due to solvent evaporation. Therefore, the ink (storage) tank is continuously adjusted in its mixture with make-up solvent from a replaceable solvent cartridge to ensure that the ink drawn from the ink tank has an acceptable viscosity.

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

[0008] When pigment-based 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 composition of the ink. The ink composition may vary depending on various characteristics, such as the desired color, the surface to be printed on, the solvent suitable for the specific application environment, and many other factors.

[0009] When the printer is in use, the filter inside the printer operates continuously. In many continuous inkjet printers, a venturi pump is used to generate suction. Such a pump typically operates at a continuous ink flow rate that far exceeds the ink flow rate supplied to the print head. In many cases, the entire ink flow is filtered by the main filter, which has a fine (e.g., 10 μm) rating, although only a small portion of the flow reaches the print nozzle. In this arrangement, the large amount of ink filtered may cause the filter wear rate to be higher than necessary. Fine particles (or pigments or other debris) will gradually cause the filter to become clogged. In addition, the sedimentation of pigment particles under gravity will cause the pigment to accumulate on the filter surface, further causing the filter performance to deteriorate.

[0010] An object of the present invention is, inter alia, to provide an improved ink filter for an inkjet printer, such as a continuous inkjet printer, which solves one or more problems (whether those identified above or otherwise) with using pigmented inks, inks containing precipitates and / or solid deposits. Summary of the invention

[0011] According to a first aspect disclosed herein, a filter module for filtering ink is provided. The filter module includes a filter housing, which defines: a filter chamber; an inlet port; a first outlet port; and a second outlet port. The filter module includes a first filter element, which includes a first filter medium disposed in the filter chamber. The filter housing is configured to define a first filtrate path from the inlet port via the first filter element to the first outlet port, and a second path from the first inlet port across the outer surface of the first filter element to the second outlet port; and when in use, the first outlet port and the second outlet port are arranged vertically above the inlet port.

[0012] The first filtrate path may be referred to as a "through flow" path (with reference to the first or primary filter medium). That is, the filtrate has flowed through the first filter medium and is therefore filtered by the first filter medium.

[0013] The second path may be referred to as a "cross-flow" path (again with reference to the first or primary filter media). That is, the portion of the fluid flowing from the inlet along the second path has flowed across the surface of the first filter media but has not necessarily been filtered by the first filter media.

[0014] The filter can be used to filter pigment ink. Specifically, the filter can be used for hard pigment ink. The filter can be used in a continuous inkjet printer.

[0015] The first outlet port may be configured to provide fluid communication with the printhead. By arranging the filters, the ink may pass through the first filter element having a particular absolute rating, without filtering all of the ink to the purity required for use in the printhead. Instead, only the volume of ink required to be supplied to the printhead is filtered to the desired filtration level. The remaining ink may pass through the filter module to provide a constant cleaning effect, and may also pass through a filter having a different (e.g., lower) absolute rating (e.g., a coarser filter).

[0016] By providing an inlet port and first and second outlet ports on the filter module, the filter can be emptied during shutdown, thereby alleviating the accumulation of sediment in the first and / or second filter element (if present).

[0017] These features may increase the life of the first filter element and the second filter element.

[0018] The filter module may be referred to as a cross-flow filter. Advantageously, the ink flow rate through the filter chamber is higher than would occur if only flow transverse to the print head flowed into the filter chamber. This is particularly advantageous because the likelihood of any precipitate in the ink settling in the first filter element is reduced. The filter housing may be sized according to printer requirements to vary the desired flow rates (i.e., through flow rate and cross-flow rate) along the first filtrate path and the second path.

[0019] The first outlet port and the second outlet port are spaced apart from the inlet port in a vertical direction and are arranged at a higher position on the filter housing when installed for use. Therefore, when used in a printer, the filter module can be arranged so that the ink is pumped in a direction including a vertical upward component from the inlet to the first and second outlet ports. In other words, the ink can be pumped through the filter in a direction opposite to the direction in which gravity acts. Therefore, the flow of ink via each of the first filtrate path and the second path can be in a generally upward direction. Advantageously, this reduces the possibility of sediment settling in the filter.

[0020] The filter module may further include a second filter element including a second filter medium disposed in the filter housing, and the second path may be a second filtrate path from the inlet port via the second filter medium to the second outlet port.

[0021] Providing the first filter element and the second filter element in a single filter housing allows for simple filter replacement, thereby reducing downtime of the printing system.

[0022] The second filter element may be disposed in the filter housing.The second filter element may 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 may have a first absolute rating and the second filter element may have a second absolute rating 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 may be configured to define a third filtrate path from the inlet port via the first filter media to the second outlet port.

[0026] The third filtrate path may 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] The second passage of the filtrate through the first filter element to the outer cavity surrounding the first filter element causes the first filter element to be "backwashed." That is, the filtrate flows in a direction opposite to the first filtrate path, reducing the extent to which filtered particles are retained by the first filter medium.

[0028] Backwashing of the first filter element is particularly advantageous when filtering pigment-based inks, and even more so when filtering hard-pigmented inks. This is because, if the flow rate of the ink through the first filter element is too low, the pigment in the ink may precipitate (i.e., settle) within the first filter element. The pigment may precipitate while the filter is in use (i.e., when ink is actively pumped through the filter), but the rate of precipitation may increase, for example, when the filter is emptied during a printing system downtime, or if the printer is shut down without emptying the filter. Pigment precipitation is undesirable because it can cause the filter element to become clogged and shorten the useful life of the filter. The third filtrate path that causes the first filter element to be backwashed mitigates the precipitation of the pigment in the first filter element, thereby helping to extend the useful life of the first filter element.

[0029] In use, only a relatively small ink flow rate is required along the first filtrate path, where the ink can then be delivered to the print head. However, as the flow rate of the first filtrate path decreases, the possibility of pigment sedimentation in the first filter element increases. Therefore, another advantage of providing a third filtrate path is that the flow rate of the first filtrate path can be reduced without causing an increase in pigment sedimentation. In other words, by providing the third filtrate path, the cross-sectional area of ​​the first filter element can be increased, which allows a desirable small flow rate along the first filtrate path while alleviating undesirable sedimentation. Therefore, not only can a desirable ink flow rate along the first filtrate path be achieved, but the service life of the filter can also be increased.

[0030] The third filtrate path may be referred to as a "counterflow" path (again with reference to the first or primary filter medium). That is, the filtrate flows through the first filter a first time and then flows back through the first filter in a reverse flow direction.

[0031] When a second filter is present, the third filtrate path may pass through the first filter medium before the second filter medium.

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

[0033] Flowing in a generally upward direction includes the ink flowing in a direction that includes a vertical component. In other words, the direction of flow of the ink includes a component in a direction opposite to gravity. Therefore, the flow of ink through the main chamber can be in a generally upward direction. Advantageously, this reduces the possibility of sediment settling in the filter. It is advantageous to allow the ink to flow in an upward direction after emptying the filter after and during shutdown. Emptying the filter during shutdown can reduce the precipitation of sediment and pigment, although some resin may be deposited on the surface of the pleated material of the first filter element, which may clog the filter. When the ink is resupplied to the filter, the precipitated resin is flushed back and suspended 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 arranged vertically above the first outlet port.

[0036] Disposing the second outlet port vertically above the first outlet port includes disposing the second outlet port vertically directly above the first outlet port, and disposing the second outlet port in an area of ​​the filter housing that is spaced vertically above the first outlet port but not necessarily in the same plane. In other words, the inlet port, the first outlet port, and the second outlet port may each define a centroid, and the vertical distance between the centroid of the inlet port and the centroid of the second outlet port may be greater than the vertical distance between the centroid of the inlet port and the centroid of the first outlet port. Thus, in use, more work must be done to overcome gravity to pump ink to the second outlet port than to pump ink to the first outlet port.

[0037] In use, arranging the second outlet port vertically above the first outlet port is advantageous because air in the chamber can leave the filter housing via the second outlet port rather than through the first outlet port which may be connected to the print head. In this way, air bubbles that may be trapped in the filter housing can be easily removed without passing to the print nozzles.

[0038] It may be further advantageous to position the second outlet port vertically above the first outlet port as this will cause ink flowing to the second outlet port to flow around or through the first filter element, thereby increasing the effective flow velocity experienced by the first filter element and thereby reducing sedimentation rate.

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

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

[0041] The second path may include a path defined between an outer surface of the first filter element and a wall of the filter housing defining the chamber.

[0042] The second (filtrate) path may surround the outermost surface of the first filter element.

[0043] Surrounding the outermost surface means that the second filtrate path can for example surround the sidewall of the first filter element, and is not limited to all surfaces surrounding the first filter element. In other words, the ink flowing to the second outlet port can span the outermost surface of the first filter element. The outermost surface can be for example the sidewall of the filter element. Compared with the ink flow rate through the second filter element, this makes the ink flow rate through the first filter element small (which is desirable for ink being supplied to the print nozzle via the first outlet port), while the ink flow rate along the second flow path is maintained at a sufficiently high speed to mitigate the precipitation of precipitate and ink pigment in the filter.

[0044] The first filter element may include a first end and a second end opposite the first end. The first end and the second end may include a first closure and a second closure, respectively.

[0045] Such an arrangement facilitates ink flow across the entire outer surface area of ​​the first filter element.The first filter element may define a sidewall extending between a first end and a second end.

[0046] The first filter element may include an outlet port engagement arrangement to facilitate ink flow to the first outlet port.

[0047] The absolute rating of the second filter medium may be greater than the absolute rating of the first filter element.

[0048] The effective surface area of ​​the first filter element may be greater than the effective surface area of ​​the second filter element.

[0049] The term effective surface area encompasses the total area of ​​the filter medium exposed to the fluid flow that is available for filtration. This effective area may be significantly larger than the geometric surface area of ​​the filter medium using a depth filter (e.g., foam, multi-layer filter, or random fiber filter).

[0050] The first filter media may be a pleated filter media.

[0051] The first filter element may include a pleat protector filter at least partially covering the pleated filter media.

[0052] The pleated filter media may be formed from polypropylene. The pleated protection filter may be formed from a material having a greater resistance to chemical ink attack, such as stainless steel. The pleated protection filter may surround an outer surface of the pleated filter media. The presence of the pleated protection filter may prevent degradation of the pleated media. Specifically, the pleated filter media may degrade over time, and portions of the pleated filter material may break away from the body of the first filter media. The pleated protection filter may prevent any free portions of the pleated filter media from mixing with the ink in the main chamber and / or being carried away from the first filter element.

[0053] The first filter element may include an output screen disposed between the pleated filter media and the first output port.

[0054] The output screen may prevent portions of the pleated filter material from passing to the first output port. The output screen may comprise a stainless steel mesh.

[0055] The absolute rated value of the first filter element can be defined by the output screen.

[0056] The first filter element may define a central cavity, and the first filter element may include a central support structure that may be disposed within the central cavity.

[0057] The nominal rating of the first filter element may be defined by the pleated filter media.

[0058] That is, the nominal performance of the first filter element may be determined primarily by the pleated filter media, rather than by any pleat guard filter or other support structure.

[0059] Alternatively or additionally, the absolute rated value of the first filter element may be defined by the pleated filter medium.

[0060] The second filter medium may include a mesh filter. The second filter medium may be formed from stainless steel or other suitable material. The nominal and / or absolute rating of the second filter medium may be defined by the mesh filter.

[0061] The first filter media may include a stainless steel mesh filter media.

[0062] In particular, the stainless steel mesh filter medium may be a stainless steel depth filter. Advantageously, the number of components of the first filter element is minimized.

[0063] The first filter medium may include a polypropylene mesh or a PTFE mesh.

[0064] The inlet port may be configured to connect to an ink pump to pump ink along at least the first, second, and third filtrate paths.

[0065] The pump may be arranged to cause a higher ink flow rate through the filter when activated. This promotes remixing of any sediment or resin that may have settled in the filter (particularly in or on the first filter element and / or the second filter element) and thereby reduces clogging of the first and second filter elements.

[0066] The first filter element may be generally cylindrical.

[0067] Providing the first filter element with a cylindrical profile can increase the surface area through which ink passes. Advantageously, the total flow rate of ink through the filter can be maintained above a predetermined minimum flow rate, thereby reducing the likelihood of sediment settling in the first filter element, while still allowing the ink to flow from the inlet to the first outlet port at a desired flow rate.

[0068] The filter module may have a circular shape (eg, generally cylindrical, with circular end faces).

[0069] The first outlet port and the second outlet port may be arranged on a single face of the filter housing.

[0070] By providing all three fluid ports on a single face, the filter module can be installed and removed in a simple operation.

[0071] 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.

[0072] The relative flow rate may be defined as the ink flow rate during printing operations, rather than the ink flow rate during cleaning or maintenance operations.During operation of the printer, the ink flow rate through the second outlet port may be at least twice the ink flow rate through the first outlet port.

[0073] The filter module may also include a presence detection feature configured to interact with a detector configured to detect when the filter is engaged with the printing system.

[0074] Suitable presence detection mechanisms or detectors may include, for example, a Hall effect sensor. The presence detection feature may include a magnet. Specifically, a magnet for a Hall effect sensor may be provided on the filter housing. Other suitable presence detection mechanisms and motion sensors may be provided. The presence detection mechanism may be used to control the operation of the pump and thereby control the flow of ink into the filter.

[0075] The filter module may also include a removal handle.

[0076] The removal handle may allow the user to grasp the filter to apply pulling force, thereby making it easier to remove the filter from the printer.

[0077] The removal handle may include one or more holes. The removal handle may include two holes. The holes may provide an opening through which an operator can grasp and manipulate (e.g., remove) the filter module. Thus, the holes may help an operator install and remove the filter module.

[0078] The filter module may also include engagement structure for engaging with complementary structure of the printer to secure the filter module in the installed configuration.

[0079] Providing an engagement structure such as a handle-like feature may allow the filter module to be securely engaged with the printer. Providing a secure engagement between the filter module and the printer may mitigate accidental release or ejection of the filter module, such as when the filter module is under pressure generated by ink being pumped through the filter module.

[0080] According to a second aspect of the present invention, there is provided a filter module for filtering ink, the filter module comprising:

[0081] A filter housing defining:

[0082] Filter chamber;

[0083] Entry port;

[0084] a first outlet port; and

[0085] a second outlet port;

[0086] a first filter element including a first filter medium disposed in a filter chamber;

[0087] in:

[0088] The filter housing is configured to define a path from the inlet port via the first filter element to the first outlet

[0089] a first filtrate path extending from the first inlet port to the outer surface of the first filter element; and

[0090] a second path to a second outlet port; and

[0091] The inlet port, the first outlet port and the second outlet port are arranged in the filter housing.

[0092] on a single face of ; and

[0093] When in use, the first and second outlet ports are arranged at the inlet

[0094] Vertically above the port.

[0095] Optional features of the first aspect of the invention may be combined with the second aspect of the invention unless the optional feature is already present in the second aspect.

[0096] According to a third aspect of the present invention, there is provided a filter module for filtering ink, the filter module comprising:

[0097] A filter housing defining:

[0098] Filter chamber;

[0099] Entry port;

[0100] a first outlet port; and

[0101] a second outlet port;

[0102] a first filter element including a first filter media disposed in a filter chamber, and a second filter element including a second filter media disposed in a filter housing;

[0103] in:

[0104] The filter housing is configured to define a path from the inlet port via the first filter element to the first outlet

[0105] a first filtrate path extending from the first inlet port to the outer surface of the first filter element; and

[0106] a second path to a second outlet port; and

[0107] The second path is from the inlet port through the second filter medium to the second outlet port.

[0108] a second filtrate path; and

[0109] When in use, the first outlet port and the second outlet port are arranged vertically from the inlet port.

[0110] Straight up.

[0111] Optional features of the first aspect of the invention may be combined with the third aspect of the invention unless the optional features are already present in the third aspect. Features of the third aspect may be combined with features of the first and / or second aspect of the invention.

[0112] According to a fourth aspect of the present invention, there is provided a filter module for filtering ink, the filter module comprising:

[0113] A filter housing defining:

[0114] Filter chamber;

[0115] Entry port;

[0116] a first outlet port; and

[0117] a second outlet port;

[0118] a first filter element including a first pleated filter media disposed in the filter chamber, and the first filter element further including an output screen disposed between the pleated filter media and the first output port;

[0119] in:

[0120] The filter housing is configured to define a path from the inlet port via the first filter element to the first outlet

[0121] a first filtrate path extending from the first inlet port to the outer surface of the first filter element; and

[0122] a second path to a second outlet port; and

[0123] When in use, the first outlet port and the second outlet port are arranged vertically of the inlet port.

[0124] Above.

[0125] Optional features of the first aspect of the invention may be combined with the fourth aspect of the invention unless the optional features are already present in the fourth aspect. Features of the fourth aspect may be combined with features of the first and / or second and / or third aspects of the invention.

[0126] According to a fifth aspect of the present invention, there is provided a filter module for filtering ink, the filter module comprising:

[0127] A filter housing defining:

[0128] Filter chamber;

[0129] Entry port;

[0130] a first outlet port; and

[0131] a second outlet port;

[0132] a first generally cylindrical filter element comprising a first filter media disposed in a filter chamber;

[0133] in:

[0134] The filter housing is configured to define a path from the inlet port via the first filter element to the first outlet

[0135] a first filtrate path extending from the first inlet port to the outer surface of the first filter element; and

[0136] a second path to a second outlet port; and

[0137] When in use, the first outlet port and the second outlet port are arranged vertically from the inlet port.

[0138] Straight up.

[0139] Optional features of the first aspect of the invention may be combined with the fifth aspect of the invention unless the optional features are already present in the fifth aspect. Features of the fifth aspect may be combined with features of the first and / or second and / or third and / or fourth aspects of the invention.

[0140] The inlet port, the first outlet port and the second outlet port of the third, fourth or fifth aspect may be arranged on a single face of the filter housing.

[0141] The filter module of the second, fourth or fifth aspect may include a second filter element including a second filter medium disposed in a filter housing, and the second path may be a second filtrate path from the inlet port via the second filter medium to the second outlet port.

[0142] The first filter media of the second, third or fifth aspect may be a pleated filter media, and the first filter element may include an output screen disposed between the pleated filter media and the first output port.

[0143] The first filter element of the second, third or fourth aspect may be substantially cylindrical.

[0144] According to the sixth aspect disclosed herein, a continuous inkjet printer is provided, comprising an ink circuit, the ink circuit comprising an ink tank, an ink pump arrangement and a filtration module for filtering ink according to the first, second, third, fourth or fifth aspect of the present invention; wherein the ink pump is configured to pump ink from the ink tank through a first inlet port for delivery along at least one of a first filtrate path and a second path.

[0145] In use, the filter module may be arranged to pump ink in a generally upward direction away from the inlet port.

[0146] That is, the filter is oriented in the printer so that the pump causes ink to be pumped through the filter in a direction that includes a component in a direction opposite to the direction in which gravity acts.

[0147] The continuous inkjet printer may also include a pressure sensor which may be configured to sense a pressure drop across the first filter element.

[0148] The continuous inkjet printer may also include a pressure sensor which may be configured to sense a pressure drop across the second filter element.

[0149] Sensing the pressure drop across the first filter element and / or the second filter element can be used to determine when the first filter element and / or the second filter element need to be replaced. The change in the pressure drop across the first filter element and / or the second filter element can be compared with a known or tested pressure drop to determine when the first filter element and / or the second filter element need to be replaced or cleaned. The pressure drop can be measured during the startup of the printer or during the shutdown of the printer. When the pressure drop reaches a predetermined value, this may indicate that the first filter element and / or the second filter element need to be replaced. The pressure sensor can be connected to a controller, wherein the controller adjusts the ink pump rate according to the pressure.

[0150] According to a seventh aspect disclosed herein, a filter housing of a filter module for filtering ink is provided. 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; the filter housing is configured to define a first filtrate path from the inlet port via the received first filter element to the first outlet port, and a second path from the first inlet port across the outer surface of the received first filter element to the second outlet port; and when in use, the first outlet port and the second outlet port are arranged vertically above the inlet port.

[0151] The filter housing may be configured to receive a second filter element.

[0152] The second outlet port may be configured to receive at least a portion of the second filter element.

[0153] The filter housing may be formed from at least two parts.

[0154] The two parts of the filter housing may be joined by spin welding.

[0155] When the filter is installed in the printer, the first outlet port and the second outlet port can be vertically separated from the inlet port. When the filter is installed in the printer, the second outlet port can be vertically separated from the first outlet port. The inlet port, the first outlet port and the second outlet port can be arranged on a single face of the filter housing.

[0156] 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 aspect of the present invention. The method comprises: placing a second filter element comprising a second filter medium having a second absolute rating in a second outlet port defined by a filter housing, the filter housing further defining an inlet port, a first outlet port and a filter chamber; and placing a first filter element comprising a first filter medium having a first absolute rating in the filter chamber.

[0157] The first absolute rating may be different from the second absolute rating.

[0158] The method may also include forming a first filter element. The forming includes: forming a pleated filter media having a central cavity; securing a first closure member to a first end of the filter media; and securing a second closure member to a second end of the filter media opposite the first end.

[0159] Prior to securing the first and second closure members, the method may include: positioning a central support structure within the central cavity; and surrounding an exterior face of the pleated filter media with a pleat guard filter.

[0160] The method may also include heat welding the first closure member and the second closure member to the pleated filter media.

[0161] The first filter element may include an outlet port engagement arrangement, and placing the first filter element in the main chamber may include engaging the engagement arrangement with the first outlet port.

[0162] The method may further include joining the two parts of the filter housing together by spin welding after placing the first filter element into the filter chamber.

[0163] The method may include: pumping ink into a filter chamber defined by a filter housing via an inlet port; filtering a first portion of the ink flowing along a first filtrate path through a first filter element disposed in the filter chamber, the filtrate flowing out of the filter chamber via a first outlet port; allowing a second portion of the ink to flow along a second path, the second path being transmitted across an outer surface of the first filter element to a second outlet port; wherein, when flowing along the first filtrate path and the second path, a flow direction of the ink may include a component in a direction opposite to gravity.

[0164] The method may further include filtering a second portion of the ink through a second filter.

[0165] Flowing the second portion of the ink along the second path may include filtering through a second filter disposed in the second outlet port.

[0166] Filtering through the first filter element may include filtering a first portion of the ink to remove particles larger than a first predetermined size; and filtering through the second filter element may include filtering a second portion of the ink to remove particles larger than a second predetermined size, wherein the second predetermined size may be larger than the first predetermined size.

[0167] That is, the second filter element may have a greater nominal rating and / or an absolute rating than the first filter element.

[0168] According to a ninth aspect disclosed herein, there is provided a method of operating a continuous inkjet printer, comprising the method of filtering ink according to the eighth aspect of the invention. The method further comprises pumping a first portion of the ink from the first outlet port to a print head of the continuous inkjet printer.

[0169] The method may further include pumping a second portion of the ink from the second outlet port to the venturi pump.

[0170] The method may further include pumping a second portion of the ink from the second outlet port to an ink tank of the continuous inkjet printer.

[0171] According to a tenth aspect disclosed herein, there is provided a filter module holding mechanism for holding a filter module of a continuous inkjet printer, comprising:

[0172] 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, wherein the second support is distal to the first support. At least one of the first and second supports includes a first retaining feature configured to retain the filter module in a locked configuration, wherein 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 retaining feature configured to latch the mechanism in the locked configuration and substantially prevent the second support from rotating relative to the first support.

[0173] Advantageously, the filter module retaining mechanism securely retains the filter module in an operating state by means of the first retaining feature, but by means of the second retaining feature, the operator can easily release the filter module in order to access the filter module. Thus, undesirable ejection of the filter module from the mechanism during use can be avoided without requiring the operator to expend considerable effort to remove the filter module.

[0174] The first support may be described as a fixed support. The second support may be described as a movable or rotatable support. The second support may be directly pivotally connected to the first support, or there may be one or more other intervening members such that the second support is indirectly pivotally connected to the first support.

[0175] The filter module can be received by at least one of the first and second supports by engagement of a port of the filter module with a corresponding port of the first or second support. One or more of the first and second supports can abut or engage the filter module to receive the filter module. The filter module is preferably receivable by the second support.

[0176] The first retaining feature can be described as a substantially axial retaining feature, as long as the first retaining feature substantially prevents the filter module from popping outward during operation. The first retaining feature can be described as a stop or buffer. When the filter module is in a locked configuration, the first retaining feature can actively engage (i.e., abut) the filter module. When the filter module is in a locked configuration, the first retaining feature cannot actively engage (i.e., abut) the filter module. The first retaining feature can engage with the filter module in a locked configuration. The first retaining feature can be used to at least offset the force exerted on the filter module due to the fluid being forced through the filter module during operation. The first retaining feature can be described as anchoring the filter module in place. The first retaining feature can take the form of a flange or other abutting feature. The first retaining feature can engage the upper surface (e.g., outer surface) of the filter module. The first retaining feature can directly engage the filter module, or can indirectly engage the filter module through one or more other intermediate members. The first retaining feature can be described as limiting the stroke of the filter module. The first retaining feature can be described as preventing the filter module from excessively moving in the axial direction. When the second support member cannot be rotated closer to the first support member, the second support member can be described as being close to the first support member.

[0177] The second retaining feature can be described as a rotary latch in addition. The second retaining feature can be described as (rotationally) fixing the first and second supports relative to each other. The second retaining feature can be described as releasably fixing the first and second supports relative to each other. When in a locked configuration, the second retaining feature can completely prevent the rotation of the second support relative to the first support. The second retaining feature can engage another of the first and second supports. Alternatively, or in combination, the second retaining feature can be configured to engage the filter module itself.

[0178] The second retaining feature may be a clip.

[0179] The clip may be described as undergoing elastic deformation in use as it is deflected by whatever feature it engages.The clip may engage the filter module (eg a protrusion of the filter module).Alternatively, the clip may engage the other of the first and second supports.

[0180] Advantageously, the clip provides a retaining feature that is easily releasable in operation.The clip preferably provides a retaining force in a direction different from the direction in which the filter module is urged in operation.

[0181] The clip may include a tapered engagement surface.

[0182] The clip may further be described as comprising a wedge-shaped surface. The tapered engagement surface is preferably narrowest at the (first) outer end, and the thickness increases from the outer end to the second end. Pushing the feature along the tapered engagement surface preferably causes the clip to elastically deform. The clip preferably includes a recess in which the retained feature is received once the clip is deformed to its maximum extent. Thus, the clip may be described as a locking feature that will remain in a stationary position and latch the mechanism in a locked configuration in terms of rotation until the clip is deformed again.

[0183] When the filter module retaining mechanism transitions from the unlocked configuration to the locked configuration, the second retaining feature may latch the mechanism in the locked configuration.

[0184] Advantageously, when the filter module retaining mechanism transitions from the unlocked configuration to the locked configuration, the second retaining feature latches the mechanism in the locked configuration, which means that latching can be achieved without manual intervention. In other words, latching can be achieved solely by movement of the first and second bodies relative to each other (e.g., automatically).

[0185] The second retaining feature may latch the mechanism in a locked configuration when the second support is rotated toward the first support.

[0186] When the second support reaches a position where the second support is closest to the first support, the second retaining feature can latch the mechanism in the locked configuration. In other words, latching can occur at the end of the travel of the second support. When the second support is pushed or forced toward the first support, the second retaining feature can latch the mechanism in the locked configuration.

[0187] The first retaining feature may include a flange of the first support.

[0188] The flange can be described as the surface of the first support member in addition. The flange can be the flat surface of the first support member. When the second support member rotates and the filter module is received by the second support member, the flange can be used to push the filter module to a plurality of ports. When the upper surface of the filter module is engaged by the flange, the retaining mechanism is arranged in the locking configuration, and the flange can ensure that the filter module is correctly received by the second support member. The flange can be used as a buffer or a stopper to prevent the filter module from being disconnected from a plurality of ports when the mechanism is in the locking configuration.

[0189] Advantageously, the flange is an easily manufactured feature that provides the necessary limit to the travel of the filter module to ensure proper placement of the filter module.

[0190] At least one of the first support and the second support that can receive the filter module can also include a plurality of ports for connecting to corresponding ports of the filter module.

[0191] The port can be described as a hole in addition. The port can include an inlet port and an outlet port. The plurality of ports preferably include an inlet port and two outlet ports. The plurality of ports can include a female connector. The corresponding male connector of the filter module can be received by the female connector. The plurality of ports are preferably provided as a part of the second support. In order to provide the second support relative to the rotation of 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.

[0192] Advantageously, multiple ports mean that the filter module can be easily connected to the filter module holding mechanism and the wider system. In addition, multiple ports provide a convenient way to releasably engage the filter module with the surrounding mechanism.

[0193] The plurality of ports may include a plurality of female connectors.

[0194] At least two of the plurality of female connectors may have different axial lengths. Each of the plurality of female connectors may have different axial lengths. In other words, at least two of the plurality of female connectors may have different heights or axial lengths.

[0195] In other embodiments, the retaining mechanism may include a male connector and the filter module may include a female connector (ie, the arrangement is reversed).

[0196] Advantageously, by providing female connectors having different axial lengths, the various ports of the filter module will effectively disconnect from the corresponding female ports at different stages when the filter module is removed from the filter module retaining mechanism. This provides a gradual disconnection so that an operator can more easily predict when the filter module will disengage. This is in contrast to an arrangement where, for example, all connectors are of the same size and therefore disconnection occurs simultaneously (which makes it difficult to predict when the filter module will disconnect, with the risk of the operator losing or misplacing the filter module).

[0197] In use, the retaining force exerted by the first retaining feature may be in a first direction and the retaining force exerted by the second retaining feature may be in a second direction different from the first direction.

[0198] The holding force applied by the first holding feature can be described as a force applied to the filter module to resist the fluid under high pressure as it passes through the filter module. The holding force applied by the first holding feature can be described as acting parallel to the axis of the multiple ports. The holding force applied by the first holding feature can be described as holding the filter module approximately axially. The holding force applied by the first holding feature can be described as a filter module holding force. The holding force applied by the first holding feature can act in a substantially linear direction. The holding force applied by the first holding feature can act in a substantially horizontal direction during use. The first holding force can be described as being applicable by the first holding feature.

[0199] The holding force applied by the second holding feature can act in a roughly rotational manner. In other words, the holding force applied by the second holding feature can be used to substantially prevent the first and second supports from rotating apart. The holding force applied by the second holding feature can be described as a latching force. The second direction of the holding force applied by the second holding feature can be around the axis of rotation defined between the first and second supports. The holding force applied by the second holding feature can be configured to offset the axial reaction force of the filter module that roughly wedges the first and second supports apart from each other. This may be at least partially due to the arcuate (e.g., dome-shaped) upper surface of the filter module. The second holding force can be described as being applied by the second holding feature.

[0200] Advantageously, by making the first and second directions different from each other, the force required to retain the filter module is effectively decoupled from the force required to latch the mechanism closed. Thus, the mechanism can provide a relatively high filter module retention force, but will not recover that high retention force to remove the filter module from the mechanism. This is beneficial in ensuring that the filter module remains retained during use, while also avoiding difficulties encountered by an operator when regularly removing the filter module for maintenance.

[0201] The filter module may be received by one of the first support and the second support in the unlocked configuration, and wherein the other of the first support and the second support may include a sensor configured to detect the filter module in at least the locked configuration.

[0202] In the unlocked configuration, the first and second supports may be said to define a filter module receiving volume. In the locked configuration, the first and second supports may be described as substantially enclosing the filter module.

[0203] Preferably, the first support comprises a sensor configured to detect the filter module. The sensor preferably detects that the filter module is correctly received by the second support and that the second support is correctly oriented relative to the first support in at least the locked configuration. The sensor may be a magnetic sensor, such as a Hall effect sensor. However, other types of sensors may be used in addition.

[0204] Advantageously, the presence of a sensor detecting the filter module can ensure that the system can only operate if the filter module is correctly received. This can prevent the system from accidentally operating if the filter module is mistakenly not replaced or incorrectly installed. The presence of the sensor can provide a fail-safe system, where the system can only operate if the filter module is correctly installed.

[0205] The filter module holding mechanism may further include an ejection mechanism for ejecting the filter module from the filter module holding mechanism.

[0206] The ejection mechanism may include a lever. The ejection mechanism may include a screw. The ejection mechanism may be used to provide an ejection force that acts on the filter module and ejects the filter module from the filter module retaining mechanism. The ejection mechanism may utilize a mechanical advantage to reduce the force required by an operator to remove the filter module.

[0207] The ejection mechanism may be mounted on at least one of the first and second supports, preferably on the second support. That is, the ejection mechanism is preferably at least partially mounted on a movable or rotatable support. The ejection mechanism may include a pivot. The ejection mechanism may be leveraged against the rear of the filter module and may be leveraged against the filter module near one or more of the plurality of ports. The ejection mechanism preferably provides at least a two-fold mechanical advantage multiplier to increase the force applied by the operator to more easily eject the filter module from the retaining mechanism.

[0208] Advantageously, the presence of the ejection mechanism makes it easier to periodically remove the filter module from the mechanism, such as for maintenance reasons.

[0209] The second support may be configured to receive the filter module in an unlocked configuration, and the first support may be a fixed support configured to retain the filter module in a locked configuration.

[0210] The second support configured to receive the filter module in the unlocked configuration can be further described as the second support configured to receive the filter module when the second support is in a rotational position away from the first support. In other words, the second support is configured to receive the filter module when the retaining mechanism is in the open configuration.

[0211] The first support is a fixed support, which means that the first support does not move when the filter module holding mechanism is switched between the unlocked and locked configurations. The holding mechanism can be fixed or mounted to the entire printer via the first support.

[0212] The first support member may be configured to directly engage the filter module. Alternatively, the first support member may indirectly engage the filter module. In a preferred embodiment, the first support member may be configured to engage the filter module at a plurality of different positions in a locked configuration. For example, the flange of the first support member may be configured to engage the upper surface of the filter module in a locked configuration, and the clip of the first support member may be configured to engage the projection of the filter module in a locked configuration (to latch the first and second support members relative to each other in terms of rotation).

[0213] The first support may include a second retaining feature.

[0214] In other words, the first support may comprise a clip.

[0215] According to an eleventh aspect disclosed herein, there is provided a component for a continuous inkjet printer, comprising: a filter module holding mechanism according to the tenth aspect of the present invention; and a filter module held by the filter module holding mechanism.

[0216] Advantageously, when the filter module forms part of a continuous inkjet printer, the filter module may be securely held in place to counteract the high forces exerted on the filter module by high pressure fluid pumped through the filter module, but may also be easily removed periodically for maintenance.

[0217] The second retaining feature may engage with a flange of the filter module in a locked configuration.

[0218] The protrusion of the filter module may additionally be described as a handle of the filter module. When the filter module is inserted into the holding mechanism, an operator may hold the protrusion (eg, handle).

[0219] Advantageously, the protrusions can be easily positioned.

[0220] According to a twelfth aspect disclosed herein, there is provided a continuous inkjet printer comprising the components of the eleventh aspect of the present invention.

[0221] According to the thirteenth aspect disclosed herein, a method for fixing a filter module in a filter module holding mechanism of a continuous inkjet printer is provided, comprising: pushing the filter module holding mechanism into an unlocked configuration, wherein the second support member is at the distal end of the first support member; placing the filter module to engage with one of the first and second supports so that the filter module is received by one of the first and second supports; pushing the filter module holding mechanism into a locked configuration, wherein the second support member is close to the first support member, the filter module is held by rotating the second support member toward the first support member, and by a first holding feature of one of the first and second supports, and engaging a second holding feature of one of the first and second supports to latch the mechanism in the locked configuration and substantially prevent the second support member from rotating relative to the first support member.

[0222] Pushing the filter module retaining mechanism into the unlocked configuration may include rotating the second support relative to the first support. The first support may be rotated up to about 20° to (rotationally) separate the second support from the first support and provide a filter module receiving volume.

[0223] Placing the filter module into engagement with one of the first and second supports preferably comprises placing the filter module into engagement with the second support.Thus, when the retaining mechanism is in the unlocked configuration, the filter module is preferably received by the second support.

[0224] Pushing the filter module holding mechanism into the locking configuration may include rotating the second support relative to the first support. This is preferably about 20 degrees. The second support is arranged near the first support and can be described as a holding mechanism that basically closes the filter module. When the mechanism is pushed into the locking configuration, the first holding feature of one of the first and second supports can engage the filter module to hold the filter module. Engaging the first holding feature of one of the first and second supports with the filter module to hold the filter module may include engaging the flange of one of the first and second supports (preferably the first support) with the filter module (e.g., the upper surface of the filter module). This can provide axial alignment of the filter module relative to a plurality of ports. When the second support rotates toward the first support, the first holding feature may at least partially cover the filter module or overlap it (e.g., to limit the stroke of the filter module). This can provide a stopper that prevents the filter module from moving beyond the first holding feature. Holding the filter module by the first holding feature may include at least partially aligning the flange with the filter module (e.g., above the filter module). The flange may be described as a buffer or a cap.

[0225] The second retaining feature that engages one of the first and second supports can include a second retaining feature that engages one or more of the filter module and another of the first and second supports to lock the first and second supports relative to each other in rotation. In a preferred embodiment, the second retaining feature is a clip provided as a part of the first support, and the clip engages the filter module (e.g., a projection thereof). When the second support rotates toward the first support, the second retaining feature is preferably engaged. In other words, the rotational action or the pushing operation can automatically bias the clip so that the filter module engages the clip without the operator manually actuating the clip.

[0226] Substantially preventing the second support from rotating relative to the first support may include preventing the second support from rotating relative to the first support. Substantially preventing rotation may still allow a small degree of rotation, but not enough to enable the filter module to be removed from the filter module receiving volume defined by the retaining mechanism. In other words, the second support may rotate slightly relative to the first support, but not to the extent that the filter module can be removed from the retaining mechanism.

[0227] Advantageously, the above method provides automatic retention of the filter module in the filter module retaining mechanism, which can securely retain the filter module while allowing an operator to easily remove the filter module when maintenance is required. In addition, the first and second retaining features are preferably used to retain the filter module in different orientations, so that the force required by the operator to remove the filter module is less than the retaining force required to secure the filter module in use.

[0228] Placing the filter module in engagement with one of the first support and the second support may include: placing the filter module in engagement with the second support; and

[0229] Pushing the filter module retaining mechanism into the locked configuration may include aligning a first retaining feature of the first support with the filter module to retain the filter module, and pushing a second retaining feature of the first support to engage to latch the mechanism in the locked configuration.

[0230] Advantageously, pushing the filter module retaining mechanism into the locked configuration as described above both aligns the filter module relative to the retaining mechanism and then secures the retaining mechanism in the locked configuration.

[0231] Placing the filter module in engagement with the second support may include inserting the filter module into a filter module receiving volume defined by the second support. Placing the filter module in engagement with the second support may include inserting a port of the filter module into a corresponding port of the second support. When the filter module is placed into the second support, the filter module may contact a support member of the second support.

[0232] The second retaining feature may engage the filter module.

[0233] The second retaining feature may be described as directly engaging the filter module.

[0234] The second retaining feature may engage a flange of the filter module.

[0235] The protrusion of the filter module that the second retaining feature engages may be described as a handle of the filter module.

[0236] Engaging the protrusion of the filter module with the second retaining feature may include pushing a tapered engagement surface of the clip past the protrusion of the filter module to latch the mechanism in the locked configuration.

[0237] Advantageously, the tapering engagement surface of the clip allows the filter module to be automatically retained by the clip. In other words, the clip can be elastically deformed by the action of the second support member rotating relative to the first support member, so that the operator does not need to deform the clip manually. Therefore, the retaining operation becomes simpler.

[0238] The method may further comprise detecting, via a sensor, that the filter module is correctly installed in at least the locked configuration.

[0239] The sensor can be a magnetic sensor, such as a Hall effect sensor. The sensor can detect that the filter module is correctly located in both the second support and the first support. In other words, the sensor can be configured to detect that the filter module is correctly located in the retaining mechanism. The sensor can 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 corresponding one or more ports of the second support. The filter module can be used to provide a signal indicating that the filter module is correctly received in the locked configuration and therefore the printer can operate. Similarly, the sensor can be used to prevent the printer from operating unless the filter module is correctly seated in the locked configuration.

[0240] It will be understood that the features described in the context of one aspect can be combined with other aspects described herein. For example, the features described in the context of the filter module above can also be applied to a continuous inkjet printer including such a filter module, or to the operating method of such an inkjet printer, or to the manufacturing method of the filter module, or to a kit of parts. Specifically, it will be understood that the filter module according to the first, second, third, fourth or fifth aspect can be used with the continuous inkjet printer of the sixth aspect. In addition, the filter holding mechanism of the tenth aspect can be used with the filter module according to the first, second, third, fourth or fifth aspect, the continuous inkjet printer of the sixth aspect, the filter housing of the seventh aspect, and the method of the eighth or ninth aspect. The assembly of the eleventh aspect and the continuous inkjet printer of the twelfth aspect can be used with any of the first to tenth aspects. BRIEF DESCRIPTION OF THE DRAWINGS

[0241] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0242] Figure 1 A continuous inkjet printer is schematically shown;

[0243] Figure 2 Schematically shows Figure 1 The ink circuit of a continuous inkjet printer shown in ;

[0244] Figure 3 Schematic diagram showing the Figure 1 A cross section of an ink filter module in a continuous inkjet printer is shown in FIG.

[0245] Figures 4A-4D Schematically shows Figure 3 Components of an ink filter element of an ink filter module shown in FIG.

[0246] Figures 5A-5C Schematically shows Figure 3 Components of the ink filter module shown in;

[0247] Figure 6 Schematically shows Figure 3 The fluid flow path within the ink filter module shown in FIG.

[0248] Figure 7 Shows Figure 3 The manufacturing process of the ink filter module is shown in FIG.

[0249] Figure 8 An ink filtration module having an alternative port arrangement is schematically shown;

[0250] Fig. 9 is a perspective view of an assembly according to another embodiment, the assembly being shown in a locked configuration, including a filter module retaining mechanism and a filter module;

[0251] Fig.10 yes Fig. 9 a cross-sectional side view of an assembly of;

[0252] Fig.11 yes Fig. 9 and Fig.10 A rear view of the assembly shown in ;

[0253] Fig.12 is a perspective view of an assembly according to another embodiment, the assembly being shown in an unlocked configuration; and

[0254] Fig.13 yes Fig.12 An isolated perspective view of the filter module retaining mechanism.

[0255] In the drawings, like parts are denoted by like reference numerals. It will be understood that the drawings are for illustration purposes only and may not be drawn to scale. DETAILED DESCRIPTION

[0256] Figure 1 An inkjet printer 101 is schematically shown. The printer 101 comprises a printer body 103 connected to a print head 105 via an umbilical cable 107. The printer body 103 may include an ink supply system and a printer controller, and the printer body 103 may have a display 109 (e.g., a touch screen) for use by an operator. The print head 105 is arranged to print on a substrate (such as a surface of an article 111) moving along a production line 113.

[0257] Reference now Figure 2 , showing Figure 11 is a simplified schematic diagram of a possible fluid system of an inkjet printer. The inkjet printer 101 includes an ink supply system 115 contained within the printer body 103. The ink supply system 115 includes an ink tank 117 for storing ink. A mixing head 123 is disposed below the fluid level of the ink tank 117 and is connected to an ink pickup line 119. The ink pickup line itself is connected to a pump 121. Therefore, the fluid in the ink tank 117 is in fluid communication with the pump 121, and the ink also passes through the mixing 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 allow ink to be supplied from the ink tank 117 to the print head 105 (as described in more detail below). The 3:2 valve also allows the pump to be connected to a mixing pickup 120 disposed within the ink tank 117.

[0258] The pump 121 can be operated in a forward direction or a reverse direction. When the pump 121 is operated in its forward direction, the 3:2 valve 122 is configured to connect the pump outlet to the filter 126, and the fluid system is said to be in a forward configuration. In the forward configuration, the pump 121 draws ink from the ink tank 117 to the 3:2 valve 122 via the mixing head 123 and the ink pickup line 119. 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.

[0259] A damper 125 is provided after the filter 126 to reduce fluctuations in ink pressure in the ink supply. A pressure sensor 129 is provided at the damper outlet and is configured to monitor the pressure at the outlet of the damper 125. A valve 127 is provided downstream of the pressure sensor 129. An ink supply line 128 is configured to transfer 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 via a pump 121, a 3:2 valve 122, a filter 126, a damper 125 and a 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 ink supply to the printhead 105.

[0260] The ink supply system 115 also includes an ink cartridge connector 131, which can be connected to an associated ink cartridge 133, and a solvent cartridge connector 135, which can be connected to an associated solvent cartridge 137. The ink cartridge 133 and the ink cartridge connector 131 are connected to an ink replenishment line 141, thereby allowing ink to be sucked through a valve 143 by a pump 145 (e.g., a diaphragm pump) and supplied to the ink tank 117.

[0261] Similarly, the solvent cartridge 137 and the solvent cartridge connector 135 are connected to a solvent replenishment line 149, allowing solvent to be supplied to the ink tank 117 via a valve 151 under the suction of the pump 145. Each of the valves 143, 151 can be independently operated, allowing ink or solvent to be supplied to the ink supply tank independently of each other under the control of the pump 145.

[0262] In some configurations, an ink reservoir and / or a solvent reservoir (not shown) may be provided to temporarily store ink or solvent between the cartridges 133 , 137 and the corresponding replenishment lines 141 , 149 .

[0263] In order to work properly, the ink supplied to the print head 115 must be within a specified viscosity range. The ink tank 117 is used as a pre-mixed ink reservoir so that any ink drawn therefrom meets the viscosity specification. By controlling the entry of ink and solvent from the ink cartridge 133 and the solvent cartridge 137, a precise mixture of ink and solvent is maintained.

[0264] As described above, in use, ink is supplied to the printhead 105 via the umbilical cord 107 along the ink pickup line 119 and the ink supply line 128. Within the printhead 105, the ink is supplied to the drop generator 155. The ink is supplied to the drop generator under pressure (under the influence of the pump 121) and is forced through the nozzle of the drop generator 155 to form an ink jet 157. The ink jet 157 starts as a constant stream of ink and, under the influence of surface tension and vibrations applied in the drop generator 155 (e.g., by a piezoelectric oscillator), gradually separates into a series of ink droplets 159, which continue to travel in the direction of the ink jet 157.

[0265] In some printers (such as Figure 2 In the printer shown in ), a purge line 158 is connected to the droplet generator. The purge line 158 can be connected to the purge port of the droplet generator 155. The droplet generator 155 can be provided as part of a droplet generator assembly, which includes a droplet generator body and a piezoelectric oscillator with known acoustic properties. The purge port can be provided by the body, or by a separate component connected to the body. The purge line 158 allows ink to flow out of the droplet generator via the purge hole without passing through the nozzle, and allows the droplet generator to be cleaned. The purge line 158 extends from the droplet generator 155 along the umbilical cord 107 and returns the ink (or solvent) to the ink supply tank 117 according to the operating stage. One or more valves (not shown) can be set in the purge line 158. It will be understood that the purge line is not required and can be omitted in some printers. In addition, additional fluid lines can be provided to support certain printer operations. For example, a solvent supply line can be provided to supply a cleaning solvent to the print head for cleaning purposes.

[0266] Shortly after emerging from the nozzle of the droplet generator 155, the ink jet 157 passes through the charging electrode 161. The point at which the continuous ink jet 157 separates into droplets 159 is arranged to occur within the charging electrode 161. The ink is a conductive liquid, and the droplet generator is typically maintained at a fixed (e.g., ground) potential. A variable voltage is applied to the charging electrode 161, causing a charge to be induced on the continuous stream of ink extending from the ink droplet generator 155 to the charging electrode 161. When the continuous ink stream (i.e., the ink jet 157) separates into droplets 159, any charge induced on the ink within the droplets is captured when the individual droplets break away from the mainstream ink 157. In this way, a variable charge can be applied to each of the ink droplets within the stream of ink droplets 159.

[0267] The stream of ink droplets 159 then continues through the electrostatic field from the charging electrode 161. In the example shown, the stream of ink droplets 159 passes between the deflection electrodes 163, 165. The first of the deflection electrodes 163 is maintained at a first voltage, while the second of the deflection electrodes 165 is maintained at a second voltage, and a large potential difference (e.g., 8-10 kilovolts) is established between the deflection electrodes 163, 165. In some systems, one electrode can be maintained at ground potential while the other electrode is maintained at a high (positive or negative) voltage (relative to ground). In other systems, one electrode is maintained at a negative voltage (relative to ground) while the other electrode is maintained at a positive voltage (relative to ground). In further alternatives, only a single deflection electrode is provided, or multiple deflection electrodes are provided. The field established by the deflection electrodes 163, 165 deflects any charged droplets (i.e., droplets that have been charged by the charging electrode 161). In this way, based on the variable charge applied by electrode 161, droplet 159 can be selectively (and variably) deviated from the path along which it is emitted from the nozzle of droplet generator 155.

[0268] Droplets that pass through the deflection field without being deflected travel to the gutter 167. The gutter 167 includes an orifice through which the droplets enter. The gutter 167 is connected to a gutter line 169 that extends from the gutter back to the ink supply system 115. Optionally, a valve 171 is provided in the gutter line 169 to enable the line to be opened and shut down. Suction is applied to the gutter line 169 by a suction system to draw ink back along the line from the gutter to the ink supply system 15.

[0269] In many inkjet printers, suction is provided by a suction system including a venturi 173 (which may also be referred to as a jet pump). The venturi 173 is disposed within the ink supply system 115 and is configured to receive a pressurized ink flow from the ink pump 121 via a venturi supply line 175, which is connected to a second outlet of the filter 126. The ink flowing from the venturi supply line 175 through the venturi 173 is returned to the ink supply tank 117 via an ink return line 177 after it passes through the venturi 173.

[0270] The venturi tube comprises a pipe having a cross section that converges and then diverges. The venturi tube creates a local area of ​​high-speed low-pressure flow by converging. The high-speed low-pressure area is connected to the suction port 178. In use, the flow cell pipeline 169 is connected to the venturi tube 173 via the suction port 178. In this way, the low-pressure area created in the venturi tube 173 is used to apply suction to the flow cell pipeline 169.

[0271] Any ink flowing into the flow cell 167 will be forced to flow along the flow cell line 169 and will eventually be drawn into the venturi 173 (via the suction port 78 ) and will exit the venturi and will flow along the return line 177 before returning to the ink supply tank 117 .

[0272] By using the venturi in this manner (ie, as a jet pump), a system can be designed in which the main system ink pump 121 can generate both positive pressure (eg, to supply ink to the printhead) and negative vacuum pressure (eg, to provide suction to the gutter).

[0273] The ink tank 117 is vented through the vent 179 to prevent excessive pressure from building up in the ink tank 117. However, it will be appreciated that venting through the vent 179 may result in the discharge of solvent vapor into the external environment, which may be undesirable (e.g., because the solvent needs to be replaced and may cause damage to the environment). In some embodiments, a capture system 180 may be connected to the vent 179 to capture solvent from the exhausted air. The capture system 180 may include a condenser. The captured solvent may be returned to another location within the ink supply system 115, such as, for example, the ink tank 117. The capture system 180 may be connected to the pump 145.

[0274] The filter 126 is used as described above to filter ink for delivery to the printhead via the ink supply line 128 and also to the venturi 173 via the venturi supply line 175. However, it will be appreciated that in alternative arrangements separate filters may be used. That is, a first filter may be provided to finely filter a relatively small amount of ink delivered to the printhead, while a second filter may be provided to more coarsely filter a larger amount of ink supplied to the venturi 173.

[0275] Now refer to Figures 3 to 7 The ink filter module 300 that can perform the dual filtering function of the above-mentioned filter 126 is described in detail.

[0276] Figure 3A schematic cross-sectional view of an ink filter module 300 is shown. The ink filter module 300 includes a filter housing 301, which includes a connecting portion 302 and a main body portion 303. The connecting portion 302 includes an inlet port 305, a first outlet port 307, and a second outlet port 309. The three ports are arranged on an end portion 302a of the connecting portion 302. The connecting portion 302 also includes a sidewall 302b. The filter module also 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 main body portion 303 includes an end portion 303a and a sidewall 303b. The sidewall 303b at least partially surrounds the first filter element 311.

[0277] The filter housing 301 includes walls 315 (including end portions 302a, 303a and side walls 302b, 303b) that define an enclosed filter chamber 317. The filter chamber 317 is fluidly connected to each of the inlet and outlet ports 305, 307, 309.

[0278] The first filter element 311 is centrally disposed in the filter chamber 317. An outer cavity 319 is defined outside the first filter element 311 in the filter chamber 317. Figures 4A-4D The first filter element 311 is shown in more detail. Figure 4A A perspective view of a first filter medium 321 is shown. The first filter medium 321 is a pleated filter medium. The first filter medium 321 is cylindrical with a central cavity 323 through which a central axis AA passes. The first filter medium 321 comprises a polypropylene filter.

[0279] Figure 4B A perspective view of a first filter medium 321 is shown, surrounded by a pleat protection filter 325. The pleat protection filter 325 may be formed from a material, such as stainless steel, that is more resistant to chemical ink attack than the material of the first filter medium 321 .

[0280] The pleated protection filter 325 surrounds the outer surface of the pleated filter media and also has a cylindrical shape. The presence of the pleated protection filter 325 is optional, but when present, it can increase the life of the pleated filter media. Specifically, the pleated filter media may degrade over time, and portions of the pleated filter material may break away from the body of the first filter media 321. The pleated protection filter 325 can prevent any free portions of the pleated filter media from mixing with the ink in the filter chamber 317 and / or being carried away from the first filter element 311.

[0281] The first filter element 311 also includes a central support member 327 ( Figure 4B321 ). The central support member 327 comprises a coarse mesh of polypropylene support elements and is provided to prevent the first filter medium 321 from collapsing.

[0282] like Figure 4C and 4D As shown in FIG. 1 , the first filter element 311 also includes a first end closure 328 (in Figure 4C The first end closure 328 is disposed at the first end 330 of the first filter element 311, and the second end closure 329 is disposed at the second end 331, opposite to the first end 330.

[0283] The first filter element 311 also includes a first filter element outlet port 333, which is centrally located on the first end closure 328 and is configured to allow ink to flow out of the central cavity 323. The first end closure 328 also includes an output screen 334 (at Figure 3 The output screen 334 is configured to prevent pleated media fragments from exiting the central cavity 323 via the port 333 (seen in cross-section in FIG. 3 ).

[0284] The shell connecting portion 302 is Figure 5A , and has a circular cross-section when viewed along axis AA (also shown Figure 4A (displayed in the figure). Figure 5B The first filter element 311 is shown inserted into the housing connection portion 302. The first filter element outlet port 333 (see Figure 4D ) is inserted into the housing connecting portion 302 (see Figure 5A ) is provided in the first filter element connector 335.

[0285] Figure 5C The filter module 300 is shown fully assembled, with the housing body portion 303 shown to be present.

[0286] The filter module 300 also includes a presence detection feature, which in the illustrated embodiment includes a magnet support 337 having an aperture 339 for receiving a magnet (not shown).

[0287] The filter module 300 also includes a removal handle 341 (eg, Figure 5C But Figure 3305 and the filter module 300. The filter module 300 is provided as a part of the main body 303 and is disposed at the end of the filter module opposite to the inlet port 305 and the outlet ports 307, 309. The removal handle 341 allows a user to grasp the filter module 300 to apply a pulling force, thereby making it easier to remove the filter from the printer. Although not shown in all figures, the removal handle 341 (if present) may also include one or more holes. Preferably, the removal handle includes two holes. The holes provide an opening through which an operator can grasp and manipulate (e.g., pull) the filter module 300.

[0288] The filter also includes an engagement structure 343 for engaging with a complementary structure of the printer to secure the filter in an installed configuration (described in more detail below). In the illustrated embodiment, the engagement structure 343 is incorporated into the handle 341. The engagement structure 343 allows the filter to be securely engaged with the printer. Providing a secure engagement between the filter and the printer can mitigate accidental release or ejection of the filter, such as when the filter is placed under pressure generated by ink being pumped through the filter.

[0289] Figure 5A Also shown is an (optional) inlet filter 345 (mostly hidden) and a second filter element 313. The second filter element 313 includes a second filter medium 314, such as a stainless steel mesh filter medium. The second filter element 313 is disposed in the filter housing 301. Specifically, the second filter element 313 is received in a portion of the filter housing that defines the second outlet port 309, such as Figure 3 As most clearly shown in the

[0290] The first filter medium 321 has a first absolute rating. The second filter medium 314 has a second absolute rating. The first absolute rating is different from the second absolute rating. The term "absolute rating" may also be referred to as the cut-off point or absolute micron rating of the filter. Such a rating defines the diameter of the largest particle that can pass through the filter medium of the filter element. In use, it is expected that less than 1% of the particles larger than the absolute filter rating will pass through the filter. An alternative filter definition is a nominal rating, where approximately 5% of particles exceeding this size may pass through even under normal operation. Thus, a filter may be defined by either a nominal rating or an absolute rating. In either case, the filter may be said to remove particles larger than a predetermined size from the filtrate.

[0291] The absolute rating of the second filter medium 314 is greater than the absolute rating of the first filter element 321. The nominal rating of the second filter medium 314 is greater than the nominal rating of the first filter element 321.

[0292] In one example, the second filter medium 314 has an absolute rating of 200 μm. The second filter element 313 may take the form of a top hat filter, a disc filter, or any convenient shape. The second filter medium 314 may be formed of a solvent compatible material (eg, stainless steel) that has a high tolerance for operation in solvent-based inks.

[0293] The first filter element 321 may have an absolute rating of 40 μm and a nominal rating of 10 μm. The pleat protection filter 325 may have an absolute rating of 40 μm.

[0294] In practice, filter ratings are chosen to provide adequate protection for the orifices they protect. Thus, a printhead and associated nozzles (which may have an orifice of a few tens of μm, e.g. 30-75 μm) are generally protected by a finer filter than a venturi (which may have an orifice of a few hundred μm or even larger, e.g. 300 μm to 1.5 mm).

[0295] The first filter medium 311 and the second filter medium 314 each also have an effective surface area, which, together with the rating, determines the rate at which ink will pass through the respective filter, as well as the rate at which the filter performance degrades over time. The term effective surface area refers to the total area of ​​the filter medium that is exposed to the fluid flow and available for filtration. Such an effective surface area may be significantly greater than the geometric surface area of ​​the filter media using a depth filter (e.g., a foam, a multi-layer filter, or a random fiber filter).

[0296] Filters with smaller effective surface areas degrade faster (for the same rating) than filters with larger effective surface areas. Thus, the effective surface area of ​​each filter medium will be selected to coincide with a convenient expected maintenance interval. For example, the second filter medium 314 may be selected to have a sufficiently large surface area that substantially all of the dust drawn into the system via the trough 67, all of the ink condensed with such dust, water, oils, and food and beverage vapors from the factory environment, as well as debris generated by the pleated filter and housing itself, may be captured by the second filter element 313 without the pressure drop across the second filter element 313 being excessive, even after one year of operation.

[0297] The effective surface area of ​​each filter will also be selected to provide sufficient fluid traversal velocity. That is, a filter that is too large may result in extremely slow fluid flow rates and lead to increased deposition. In addition, since it is best to empty the filter module 300 (e.g., into the ink tank 17) during downtime, the total fluid volume of the filter module 300 should be minimized. Therefore, it will be understood that the optimal size of each filter depends on the specific performance and maintenance requirements of the printer 1.

[0298] The effective surface area of ​​the first filter medium 321 is significantly larger than the effective surface area of ​​the second filter medium 314 .

[0299] During normal use, the ink flow rate through the second filter element 314 is greater (e.g., at least two times) than the ink flow rate through the first filter element 311. For example, during normal use, the ink flow rate to the print head 5 may be about 4-6 ml / min. On the other hand, the ink flow rate through the venturi tube 73 may be about 100 times the ink flow rate to the print head 5.

[0300] The first filter element 311 has a cylindrical shape. This shape conveniently provides a large surface area through which the ink can pass. Advantageously, the total flow rate of the ink through the filter module 300 can be maintained above a predetermined minimum flow rate, thereby reducing the possibility of sediment being deposited in the first filter element 311, while also allowing the ink to be transferred from the inlet port 305 to the first outlet port 307 at a desired flow rate.

[0301] The second filter element 313 also has a cylindrical shape. The second filter medium 314 comprises a mesh filter, such as, for example, a stainless steel mesh filter.

[0302] The nominal rating of the first filter element 321 is defined by the pleated filter media. The absolute rating of the first filter element 321 is defined by the output screen 334. Thus, the performance of the first filter element is primarily determined by the pleated filter media, rather than the pleat protection filter 325, the support structure 327, or the output screen 334. That is, the lowest nominal rating is provided by the first filter media 311, which is operable to block the majority of particles blocked by the filter element 321.

[0303] In an alternative arrangement, the first filter medium 321 may include a stainless steel mesh filter medium. For example, the first filter medium may be a stainless steel depth filter. Advantageously, the number of components of the first filter element will be minimized. Alternatively, the first filter medium may include a polypropylene mesh or a PTFE mesh.

[0304] The output screen 334 can be a stainless steel mesh and can allow the printer to continue to operate for a short period of time without significant component damage even after the pleated first filter medium 321 is severely degraded. Alternatively, the output screen 334 can be formed of a solvent-compatible material with high resistance to solvent-based inks. The output screen 334 can have an absolute rating similar to that of the first filter medium 321.

[0305] like Figure 3As can be seen in FIG. 3 , when the filter module 300 is fully assembled, the first filter element 311 is disposed within the filter chamber 317. The first end closure 328 abuts against the inner wall of the filter housing 301, securing the position of the first filter element 311 within the housing 301. The second end closure 329 can be spaced apart from the inner wall of the filter housing 301. The first filter element 311 defines a generally cylindrical sidewall extending between a first end 330 and a second end 331.

[0306] Figure 3 Filter module 300 is shown in an "in-use" orientation. That is, when filter module 300 is installed in printer 100, it is oriented with axis AA aligned horizontally, with the positive z direction representing the direction opposite to gravity.

[0307] The inlet port 305 is provided at the bottom, the first outlet port 307 is provided in the center, and the second outlet port 309 is provided at the top. In use, ink is pumped into the inlet port 305 by the ink pump 21 and exits from the first outlet port 307 (to supply the print head 5) and exits from the second outlet port 309 (to supply the venturi 73).

[0308] The filter module is particularly well suited for filtering pigment-based inks, such as Figure 1 and Figure 2 Hard pigmented ink in a continuous inkjet printer of the type described. The filter module 300 is arranged so that the ink can pass through a first filter element 311 having an absolute rating (or effective pore size) different from that of a second filter element 313, without filtering all of the filtered ink to the purity required for use in the printhead 5. Instead, only the (relatively small) ink flow rate that needs to be supplied to the printhead is filtered to the desired filtration level. The remaining ink can pass through a second filter element 313 having a different absolute rating (or effective pore size) for more coarse filtering. Such a filter (i.e., the second filter element 313) can prevent larger debris or particles from reaching the venturi tube 73. However, it has been recognized that filtering all of the ink at a high absolute rating can result in excessive degradation of filter performance, thereby shortening maintenance intervals (for replacement of clogged ink filters).

[0309] In addition, the first filter element 311 and the second filter element 313 are arranged in a single filter housing (i.e., housing 301), allowing for simple replacement of the filter module 300, reducing downtime of the printing system, and minimizing waste. It will be appreciated that the first filter element 311 and the second filter element 313 can be designed so that they are expected to need to be replaced at similar times, thereby minimizing unused filter capacity.

[0310] Figure 6A simplified cross-sectional view of the filter module 300 is shown. A first filtrate path 350 is defined from the inlet port 305 via the first filter medium 321 to the first outlet port 307. The first filtrate path 350 is shown as passing through the first filter medium 321 at the filtering position 351. The first filtrate path 350 then emerges into the central cavity 323, and then exits via the first filter element outlet port 333, the first filter element connector 335 (provided by the housing connection portion 302), and the first outlet port 307. Therefore, the filtrate 350F leaving the first outlet port 307 includes a portion of the fluid flowing into the inlet port 305, which is filtered by the first filter medium 321. There is no path from the inlet port 305 to the first outlet port 307 that does not pass through the first filter medium 321. The first filtrate path can be referred to as a "through flow" path (with reference to the first filter medium 321). That is, the filtrate 350F has flowed through the first filter medium 321 and is thereby filtered by the first filter medium 321.

[0311] The second filtrate path 352 passes from the inlet port 305 through the outer surface of the first filter element 311 in the outer cavity 319, and then reaches the second outlet port 309 via the second filter medium 314. The second filtrate path 352 is shown as passing through the second filter medium 314 at the filtering position 353, and then exits via the second outlet port 309. Therefore, the filtrate 352F exiting from the second outlet port 309 includes a portion of the fluid flowing into the inlet port 305, which is filtered by the second filter medium 314. The second filtrate path 352 effectively bypasses the first filter element 311. Although the second filtrate path 352 is shown as bypassing the second end 331 of the first filter element 311, it will be understood that there are several paths that constitute the second filtrate path 352. Some of these paths bypass the perimeter of the first filter element 311. For example, the second filtrate path 352 includes a path defined between the outer surface of the first filter element 311 and the wall of the main chamber defined by the filter housing 301.

[0312] Other paths of the second filtrate path 352 can bypass the first end closure 328 (bypassing the first filter outlet 333). Thus, the second filtrate path effectively surrounds the outermost surface or outer surface of the first filter element 311. However, it will be understood that the second filtrate path does not necessarily completely surround all surfaces of the first filter element. That is, ink flowing to the second outlet port 309 spans a portion of the outermost surface of the first filter element (e.g., the sidewall of the filter element) or the pleated protective filter 325.

[0313] The second filtrate path may be referred to as a “cross-flow” path (again with reference to the first filter medium 321 ). That is, the filtrate 352F has flowed across the surface of the first filter element 311 , but has not yet been filtered by the first filter medium 321 .

[0314] A third filtrate path 354 is defined from the inlet port 305 through the first filter medium 321 and then the second filter medium 314 to the second outlet 309. The third filtrate path 354 is shown passing through the first filter medium 321 at a filtering position 355. The third filtrate path 354 then emerges into the central cavity 323 before exiting (a second time) via the filter medium 321 at a filtering position 356 to the outer cavity 319 surrounding the first filter element 311. The third filtrate path then passes between the housing 301 and the filter element 311 before passing through the second filter medium 314 at a filtering position 357 before exiting via the second outlet port 309. Thus, the filtrate 354F exiting the second outlet port 309 includes a portion of the fluid flowing into the inlet port 305 that is filtered by the second filter medium 314 as well as the first filter medium 321 (twice). The third filtrate path may be referred to as a "countercurrent" path (again with reference to the first filter medium 321). That is, the filtrate has flowed through the first filter medium 321 for the first and second time, the second time in a direction opposite to the main body flow direction. The second passage of the filtrate through the first filter element to the outer region surrounding the first filter element causes the first filter element to be "backwashed". The flow of the filtrate in a direction opposite to the first filtrate path reduces the degree to which the first filter medium retains the filtered particles.

[0315] Providing cross-flow and counter-flow filtrate paths allows for a higher total flow rate of ink through the filter module than would occur if only fluid traversing to the printhead flowed through the filter. This is particularly advantageous because any precipitate in the ink is less likely to settle in the first filter element due to the higher total flow rate. The size and configuration of the filter housing 301 depends on the printer requirements to vary the desired cross-flow rate, through-flow rate, and counter-flow rate.

[0316] The second filtrate path 352 (cross flow) represents the majority of the total flow of ink within the filter because the flow restriction in this path is relatively limited compared to the first filtrate path 350 that must pass through the first filter element 311. Of course, it will be understood that the flow through the filter module 300 and the relative distribution of the flow between the first, second and third filtrate paths can be changed by changing the size of the gap between the first filter element 311 and the filter housing wall 315 and by changing the characteristics of the first filter element 311 itself. In some cases, the flow along the third filtrate path may be minimal, or even negligible. However, at other times (e.g., during the refilling of the filter chamber 317 with ink), the flow of air and / or ink along the third filtrate path may be more significant. It will also be understood that in all cases, it may not be possible to clearly distinguish between different filtrate paths. The flow of fluids (ink and air) within the filter module 300 will be complex and sometimes turbulent.

[0317] It should also be noted that fluid flow through the pleated first filter medium 321 (whether as part of the first or third filtrate paths 350, 354) may generally include fluid elements flowing across the surface of the first filter medium 321 before finding a path through the pleated filter medium.

[0318] The first, second and third filtrate paths 350, 352, 354 are paths by which ink may flow within the filtration module 300 during normal operation of the printer.

[0319] like Figure 3 309 is shown in FIG. 300 , when the filter module 300 is configured for use, the first outlet port 307 and the second outlet port 309 are arranged vertically above the inlet port 305. It can be seen that the first outlet port 307 and the second outlet port 309 are spaced apart from the inlet port 305 in the vertical direction (i.e., the z direction). Therefore, when the filter housing 301 is installed for use, the outlet ports 307, 309 are arranged at a higher position on the filter housing 301. Therefore, during normal use, each of the first, second, and third filtrate paths includes a vertical upward component from the inlet to the first and second outlet ports. Therefore, the filter module 300 is arranged to allow ink to flow from the inlet port 305 to the first and second outlet ports 307, 309 in a generally upward direction. Therefore, the ink flow through each of the first, second, and first filtrate paths can be in a generally upward direction. Advantageously, this reduces the possibility of sediment being deposited in the filter.

[0320] Flowing in an upward direction or a substantially upward direction includes the ink flowing in a direction including a vertical component. In other words, the direction of flow of the ink includes a component in a direction opposite to gravity.

[0321] Thus, the overall flow of ink through the filter chamber 317 is in a generally upward direction. Advantageously, this reduces the likelihood of sediment settling within the filter module 300. It is also advantageous to allow the ink to flow in an upward direction after shutdown and after the filter is emptied during shutdown. Emptying the filter during shutdown can reduce the precipitation of sediment and pigment. However, some resin may be deposited on the surface of the pleated material of the first filter element 311, which may clog the filter. When ink is resupplied to the filter after shutdown, the precipitated resin is flushed back into suspension in the ink and does not clog the first filter element 311. Allowing the filter to be emptied in this manner can increase the life of the first filter element 311 and the second filter element 313.

[0322] from Figure 3309 are vertically separated from each other. Specifically, the second outlet port 309 is arranged vertically above the first outlet port 307. Although such an arrangement is not necessary (the outlet ports can be in similar vertical positions, or vice versa), providing an outlet (e.g., the second outlet 309) at the top of the housing 301 allows air to be introduced into the filter chamber 317 when the filter module 300 is emptied (e.g., during an expected idle period), and to be exhausted from the filter chamber 317 when the filter module is refilled after being emptied.

[0323] In other words, the inlet port 305, the first outlet port 307, and the second outlet port 309 may each define a center of mass, and the vertical distance between the center of mass of the inlet port 305 and the center of mass of the second outlet port 309 may be greater than the vertical distance between the center of mass of the inlet port 305 and the center of mass of the first outlet port 307. Thus, in use, more work must be done against gravity to pump ink to the second outlet port 309 than to pump ink to the first outlet port 307.

[0324] The second outlet port 309 may be located directly vertically above the first outlet port 307 (as shown). However, in some variations, the second outlet port 309 may be disposed in an area 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. The offset may be applied in either the x-direction or the y-direction.

[0325] In use, it is advantageous to arrange the second outlet port 309 vertically above the first outlet port 307, because any air in the chamber 317 can leave the filter housing 301 via the second outlet port 309, rather than through the first outlet port 307 which can be connected to the print head 5. In this way, bubbles that may be trapped in the filter housing 301 can be easily removed without being transferred to the print nozzle. The second outlet port 309 can be arranged at the top of the chamber 317, thereby allowing the air retained in the filter to be exhausted. Of course, this benefit can be achieved in the case where the second outlet port 309 is not exactly located at the top of the chamber 317.

[0326] As described above, the flow of ink along the first filtrate channel 350 is in a direction substantially opposite to the direction in which gravity acts. Similarly, the flow of ink along the second filtrate channel 352 is in a direction substantially opposite to the direction in which gravity acts. Furthermore, the flow of ink along the third filtrate channel 354 is in a direction substantially opposite to the direction in which gravity acts.

[0327] If an unexpected power outage occurs, any pigment will settle to the bottom of chamber 317 (i.e., Figure 3, in the negative z-direction). By providing an inlet port 305 near the bottom of the filter module 300, pressurized ink entering the filter at system startup will agitate any settled ink pigments and remix the pigments. However, it will be appreciated that the port inlet 305 need not be located directly at the bottom of the chamber 317 to achieve this benefit.

[0328] During planned printing downtime, the contents of the filter chamber 317 can be drained into the ink tank, thereby reducing the risk of precipitation within the filter module 300. During such downtime, the filter can be maintained in a saturated vapor environment, minimizing ink drying and reducing the difficulties associated with re-wetting. This can be achieved by maintaining a fluid connection between the solvent-saturated atmosphere in the ink tank 117 and the internal volume of the filter chamber 317. This treatment of the filter can allow for downtime events of approximately one month or more.

[0329] When started after a downtime period, the pump 21 may be arranged to provide a higher ink flow rate through the filter module 300. This promotes remixing of any sediment or resin that may have settled in the filter module 300, particularly in or on the first filter element 311 and / or the second filter element 313, thereby reducing the likelihood of clogging of the first and second filter elements 311, 313.

[0330] During the startup process, as the filter chamber 317 is refilled with ink, the geometry of the first, second, and third filtrate paths 350, 352, 354 and the filter module input and outlet ports 305, 307, 309 described above will allow substantially all of the air to be exhausted from the chamber 317 in an efficient manner. Specifically, as ink is reintroduced at the inlet 305, the ink level in the chamber will begin to rise around the first filter element 311. A portion of the ink will pass through the first filter element into the central cavity 323, then exit the cavity 323 via the first outlet port 307 along the first filtrate path 350. The majority of the ink will bypass the first filter element 311 via the outer cavity 319, then exit the cavity via the second outlet port 309 (and the second filter element 313) along the second filtrate path 352.

[0331] The air in the chamber 317 will be exhausted primarily from the second outlet port 309. However, it will be appreciated that a rise in the ink level will cause air to be displaced from the central cavity 323 at a rate substantially greater than that which can be accommodated by the first outlet port 307 (typically allowing about 4-6 ml of ink per minute to flow to the printhead). Thus, the air in the central cavity 323 will be displaced through the upper portion of the first filter element and into the outer cavity 319. This air flow, and then the ink flow, will follow the third filtrate path 354 described above. The flow of air and ink (including periods of mixed flow) through the first filter element 311 (e.g., at the filtering position 356) will produce a cleaning effect on the first filter medium 321. In some embodiments, the 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 leave the central cavity 323 through the first outlet port 307, air can be prevented from moving out of the central cavity 323 through the print head, and instead substantially all of the air is moved out to the outer cavity 319 and then out through the second outlet port 309.

[0332] Eventually, after an extended period of use, it will be necessary (or at least advisable) to replace the filter module 300 in the printer 1. By arranging the inlet port 305, the first outlet port 307, and the second outlet port 309 on a single face of the filter housing 301 (i.e., at the first end 330), the filter module can be installed and removed in a simple operation.

[0333] The handle 341 can be removed by pulling it in the axial direction (ie, in the positive x direction). Figure 3 300). The removal handle allows the user to grasp the filter to apply pulling force to allow the filter to be more easily removed from the printer.

[0334] A replacement filter module may be installed by aligning the ports 305, 307, 309 with corresponding female ports provided in the printer and pushing the filter into place. Mechanical guide features (not shown) may be provided to ensure correct orientation and alignment.

[0335] The printer 1 can be configured to detect that 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 hole 339 and supported by the magnet support 337. The printer 1 includes a Hall effect sensor arranged 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, thereby controlling the flow of ink into the inlet port 305.

[0336] The magnet support 337 may also be used as an alignment feature (although alternative features may be provided, such as a protruding member or rib extending from one side of the filter housing). This is advantageous because it ensures the correct orientation of the filter module when it is set in the printer. In some arrangements, the filter module may be symmetrical. However, when this is not the case (for example, when the inlet filter 345 is not provided), it may be important that, in use, the second outlet port 309 is the uppermost port and the inlet port 305 is the lowermost port.

[0337] The filter also includes an engagement structure for engaging with a complementary structure of the printer to secure the filter in an installed configuration. Providing a secure engagement between the filter and the printer can mitigate accidental release or ejection of the filter, such as when the filter is under pressure generated by ink pumping through the filter.

[0338] The filter module 300 has been described above in the context of a specific type of continuous inkjet printer 1. However, it will be appreciated that alternative ink circuits or printer types may be used. Thus, the filter module 300 is generally usable in conjunction with a continuous inkjet printer comprising an ink circuit including an ink tank (e.g., tank 17), an ink pump arrangement (e.g., pump 21).

[0339] As mentioned above, the printer 1 comprises a pressure sensor 29. The pressure sensor is configured to sense the pressure within the ink supply line 28 downstream of the filter module 300 (ie downstream of the first outlet port 307).

[0340] In some embodiments, a pressure sensor may be provided to measure the pressure drop between the inlet port 305 and the first outlet port 307. Alternatively, or in addition, a pressure sensor may be provided to measure the pressure drop between the inlet port 305 and the second outlet port 309. In this way, the pressure drop across the first filter element 311 and / or the second filter element 313 may be measured. In some embodiments, a single pressure sensor may be configured to sense pressure in multiple locations, for example, connected to the first outlet port 307 and the second outlet port 309 via a switchable valve arrangement (not shown).

[0341] Sensing the pressure drop across the first filter element and / or the second filter element can be used to determine when the first filter element and / or the second filter element 311, 313 need to be replaced. The measured change in the pressure across the first filter element and / or the second filter element can be compared with a known or tested pressure drop to determine when the first filter element and / or the second filter element need to be replaced or cleaned. The pressure drop can be measured during the startup of the printer or during the shutdown of the printer. When the pressure drop reaches a predetermined value, this may indicate that the first filter element and / or the second filter element need to be replaced. The pressure sensor can be connected to a printer controller. Such a printer controller can be configured to control the printer based on the pressure reading (e.g., adjust the ink pumping rate according to the pressure reading) to maintain the desired pressure in the ink supply line 28 and maintain the desired flow rate through the venturi tube 73 despite filter degradation.

[0342] In some examples, pressure sensors are provided to sense pressure at both filter outlet ports 307, 309. This arrangement is particularly beneficial when the filter has two outlet ports 307, 309, because a pressure sensor that monitors only the pressure downstream of the second filter element 313 may not detect a blockage of the first filter element 311, and vice versa. If only a single pressure sensing location is provided (e.g., in the ink supply line 28), it is possible that the printer cannot compensate for the loss of venturi flow rate, resulting in reduced gutter suction and ultimately ink return failure.

[0343] Pressure sensor readings can be taken during printing or when printing is not in progress. In fact, filter degradation is a process that typically occurs over an extended period of time. Thus, pressure sensing can be performed during a startup or shutdown sequence. This operation can allow for convenient use of a single pressure sensor connected to different pressure sensing locations (e.g., input port 305, output port 307, and output port 309) in sequence, with the printer controller then taking appropriate action (e.g., modifying a pump control signal based on the pressure reading, and / or generating an alert).

[0344] The filter module 300 has been described above in an assembled form. However, it will be understood that the components of the filter module 300 may also be provided separately. For example, the first and second filter housing components (i.e., the connecting portion 302 and the main body portion 303) may be provided separately. During the manufacturing process, the filter module 300 may be constructed according to the following steps, such as Figure 7 Shown.

[0345] In a first step S1, a pleated medium is obtained and cut into a desired size. In a second step S2, the seams between the ends of the pleated medium are cut by welding (e.g., ultrasonic welding) to form the cut pleated medium into Figure 4AThe cylindrical form of the first filter medium 321 is shown in FIG. In a third step S3, the welded pleated medium (ie, the first filter medium 321) is assembled with the center support 327 and the pleated protection filter 325. In step S4, the output screen 334 is welded to the first end closure 328.

[0346] In step S5, the assembled first end closure 328 and second end closure 329 are welded to either end of the first filter medium 321 together with the central support 327 and the pleated protection filter 325. An O-ring 333a is provided around the first filter element outlet port 333. Both the first and second end closures 328, 329 are welded (e.g., by heat welding). The assembled components are as follows: Figure 4D (O-ring 333a is not shown). It will be understood that steps S1, S2 and S3 can be performed in parallel with step S4, but must be performed before step S5.

[0347] In the subsequent step S6, the housing protection part 302 is provided. In step S7, filters are inserted into the inlet port 305 and the second outlet port 309. The second filter element 313 is provided as a filter at the second outlet port. The same inlet filter may be provided in the inlet port 305, but may be omitted (e.g. Figure 3 (displayed in the figure).

[0348] In a subsequent step S8 , the assembled first filter element 321 (from step S5 ) is inserted into the housing connection part 302 (from step S7 ), wherein the first filter element outlet port 333 engages with a suitably arranged first filter element connection portion 335 provided by the housing connection part 302 .

[0349] In the subsequent step S9, the housing body part 303 is provided and joined to the assembled housing connection part 302. The joining between the two housing members 302, 303 can be performed by spin welding. Using spin welding is advantageous because it does not require other materials, provides good sealing, and does not rely on chemical adhesives.

[0350] In the subsequent step S10 , O-rings 305a , 307a , and 309a may be provided in grooves on each of the inlet port 305 , the first outlet port 307 , and the second outlet port 309 . In the subsequent step (not shown), a magnet may be inserted into the magnet hole 339 .

[0351] Before assembly, various components have been manufactured separately. For example, the housing parts 302, 303 can be formed by injection molding.

[0352] Various joining methods are described above, including heat welding, ultrasonic welding and spin welding. Adhesives may 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.

[0353] However, it is important to note that some welding processes may cause shavings and other plastic particles generated during processing to become trapped within the filter housing 301. The filter housing 301 is typically made of polypropylene, which itself may begin to degrade after extended periods of use, generating more debris. These deposits (whether generated during manufacturing or during use) are preferably captured by a filter (e.g., second filter element 313) to minimize the risk of them causing blockages elsewhere in the printer.

[0354] Of course, it will be appreciated that the above-described manufacturing and assembly methods are provided as examples only. Alternative manufacturing and assembly methods may be used. Furthermore, when the individual components described herein are subsequently joined together, they may be referred to as single components. On the other hand, when composite components are described herein, they may be provided by individual components joined together by any convenient method.

[0355] In the above examples, O-rings are used to seal the various ports. However, in some alternative examples, it may be preferred to use an interference fit in order to minimize deformation or warping of the plastic of the filter housing and end closures.

[0356] In another alternative example, the filter housing can be formed of stainless steel. In some embodiments, the filter size can be increased to provide an expected filter life comparable to the life of the printer. Of course, such filters may still need to be replaced when the filter becomes clogged or contaminated (e.g., due to extreme operating conditions).

[0357] exist Figure 8 In the alternative arrangement shown in , an alternative filter module 300' is provided. The structure of the alternative filter module 300' is similar to the filter module 300 described above. However, each of the inlet port and the outlet port is provided with an orifice 305', 307' and 309', which has an internal O-ring 305a', 307a' and 309a' instead of an external O-ring 305a, 307a' and 309a'. The printer for this arrangement includes appropriately arranged protrusions 305b', 307b' and 309b' for engaging with the orifices 305', 307' and 309'. In this arrangement, an O-ring can be set around the protrusion. At each filter replacement interval, the O-ring is replaced.

[0358] This arrangement may be preferred as it allows the arrangement to be cleaned more thoroughly at each service interval.That is, when the filter module 300' is replaced, any debris captured within the apertures of the filter module 300' will be removed.

[0359] It should also be noted that the first filter element 311 is coupled to the housing via the outlet 333 and the corresponding connector 335. An O-ring 333a is provided at the coupling portion. In alternative embodiments, the O-ring may be omitted and the filter assembled by interference fit or welding.

[0360] The filter module 300 may be provided with a data storage device (e.g., an RFID tag) configured to contain information about the filter configuration, date of manufacture, batch number, etc. The printer may query such data storage device to ensure compatibility between the filter module and the printer in which it is to be installed. Alternatively, such data storage device may be provided to track components.

[0361] In the above example, the second filter element 313 is described as being disposed within the filter module 300. Specifically, the second filter element 313 is described as being disposed within the second outlet port 309. However, it will be appreciated that alternative arrangements are possible. For example, the second filter element 313 may be omitted entirely. Alternatively, the second filter element 313 may be disposed in an alternative position, such as outside the filter module 300, between the second outlet port and the venturi 73. In some alternative arrangements, the venturi pump may be omitted entirely, and flow trough suction may be provided by an additional pump. In this arrangement, the second outlet port 309 may be discharged directly to the ink tank 317, with or without further filtering.

[0362] Furthermore, the filter system described above relates to a user-replaceable filter module. However, it will be appreciated that in some examples, the filter may be integrated with one or more other components of the printer. For example, the filter may be combined with a damper. Furthermore, the filter having the general geometric arrangement described above may be incorporated into an ink tank.

[0363] Fig. 9 4 is a perspective view of an assembly 400 of a continuous inkjet printer. The assembly 400 includes a filter retaining mechanism 402 (described in detail below) and a filter module 300.

[0364] As described above, filter retaining mechanism 404 is configured to retain filter module 300. Specifically, filter retaining mechanism 402 is configured to removably retain filter module 300 such that filter module 300 is fixed in place during use but can be periodically removed for repair and other maintenance.

[0365] The filter holding mechanism 402 includes a first support member 406 and a second support member 408. The second support member 408 is pivotally connected to the first support member 406. In other words, the second support member can rotate relative to the first support member 406. The second support member 408 can rotate about a rotation axis 410. Therefore, the second support member 408 can rotate relative to the first support member 406 in the direction indicated by arrow 412 (e.g., about the z-axis) (although as shown in FIG. Fig. 9 , the second support 408 is shown at one end of a rotational travel and thus cannot be rotated further in a generally clockwise direction). The second support may alternatively be described as a rotatable or removable support.

[0366] In the illustrated embodiment, the first support 406 is a fixed support. That is, when the filter module 300 is removed from or inserted into the mechanism 402, the first support 406 does not rotate. Therefore, the first support 406 can be further described as a fixed support. The filter holding mechanism 402 can be installed in the entire printer via the first support 406.

[0367] In the illustrated embodiment, the first support 406 includes a first retaining feature 414 and a second retaining feature 416. However, in other embodiments, one or more of the first retaining feature 414 and the second retaining feature 416 may additionally form a portion of the second support 408. In the illustrated embodiment, the first retaining feature 414 includes a flange of the first support 406. From here on, the flange will be indicated by the numeral 414.

[0368] like Fig. 9 4, when the filter retaining mechanism 402 is in the locked configuration, the upper surface (e.g., outer surface) 418 (e.g., cover) of the filter module 300 is at least partially covered (e.g., aligned) by the flange 414 of the first support member 406. Specifically, the upper surface 418 of the filter module 300 overlaps the underside of the flange 414. The flange 414 is effectively used to limit the travel of the filter module 300 and prevent the filter module 300 from moving relative to the first support member 406 in the x-direction. Fig. 9 4. The filter module 300 is moved in the direction marked 420 in the figure beyond the point at which the upper surface 418 contacts the flange 414. In use, the filter module 300 is urged in the direction 420 (e.g., in the x-direction) by the pressure of the fluid pumped through the filter module 300 (e.g., entering and then flowing out). If not retained in place, the filter module 300 is likely to be ejected from the mechanism due to the pressure of the fluid pumped therethrough.

[0369] The challenge in retaining the filter module 300 is that the upper surface 418 is generally dome-shaped (i.e., at least partially arcuate). A single constraint (e.g., only the flange 414 alone) may result in the upper surface 418 effectively forcing the filter module 300 to disengage the mechanism 402 due to the interaction of the upper surface 418 and the flange 414. In other words, when the force 420 is effective to wedge the second support member 408 away from the first support member 406, the filter module 300 may push itself out of engagement with the mechanism 402. The present invention overcomes this problem, as described in detail below.

[0370] Continuing with the description of the first support 406, in the illustrated embodiment, the first support 406 also includes a second retaining feature 416, which can be further described as a rotary latch. The second retaining feature 416 takes the form of a clip in the illustrated embodiment. Therefore, the clip will be represented by the numeral 416 moved forward. The clip 416 is configured to latch the mechanism 402 in place. Fig. 9 406. Thus, the clip 416, when engaged, substantially prevents the second support 408 from rotating relative to the first support 406. Although in the illustrated embodiment, the clip 416 engages the protrusion 422 (e.g., handle) of the filter module 300, it will be appreciated that in other embodiments, the clip 416 may otherwise engage the second support 408. Similarly, although the second retaining feature takes the form of a clip 416 in the illustrated embodiment, in other embodiments, other rotational latch mechanisms (e.g., pivot arms) may be used instead.

[0371] The clip 416 includes a tapered engagement surface 424. In other words, the tapered engagement surface 424 is generally wedge-shaped (eg, triangular). Fig. 9 4, the thickness of the clip 416 is relatively narrow at the first end 426, which is the first end that engages with the protrusion 422 of the filter module 300 when in use, compared to the second end 428 of the tapered engagement surface 424. It can be understood that when the filter module 300 is pushed to engage with the first support member 406, the protrusion 422 of the filter module 300 first contacts the first end 426 of the clip 416. As the thickness of the clip 416 increases as it moves toward the second end 428 (e.g., in the y direction), the clip 416 is elastically deformed (e.g., pushed in the x direction) by the continued movement of the protrusion 422 of the filter module 300. At the second end 428 where the protrusion 422 contacts the clip 416, the clip 416 is at its maximum elastic deformation. Once the protrusion 422 moves past the second end 428, the protrusion 422 is received in the recess 430 of the clip 416. As the protrusion 422 moves past the second end 428 of the clip 416, the clip 416 returns to a rest configuration (e.g., substantially no elastic deformation) to receive the protrusion 422 in the recess 430. In other words, the clip 416 rebounds (e.g., in the negative x-direction). Fig. 9 As can be seen, it will be appreciated that unless the clip 416 is deformed again to allow the second end 428 to exit (eg, pass over) the protrusion 422 , the protrusion 422 , and the filter module 300 , will remain retained by the clip 416 .

[0372] For completeness, the clip 416 also includes a notch 434 along a portion of its extent. Due to the presence of the notch 434, the clip 416 is more easily deformed, and therefore easier to push the protrusion 422 of the filter module 300 through the tapered engagement surface 424 into the recess 430. Although the clip 416 is used as a second retaining feature in the illustrated embodiment, it will be understood that other retaining features can be used to achieve a similar rotary latch. For example, a hinge latch can be used in addition.

[0373] Turning to the second support 408, as previously described, the second support 408 is pivotally connected to the first support 406. Thus, the second support 408 can rotate relative to the first support 406 in the direction 412 about the axis of rotation 416 (and thus about the z-axis). In the illustrated embodiment, the rotation is provided by a pair of shafts 434 ( Fig. 9 The pair of shafts 434 form part of the second support member 408. The pair of shafts 434 penetrate corresponding holes 436 (again, Fig. 9 Only one is visible in the figure), which hole forms part of the first support member 406.

[0374] The second support 408 also 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. Thus, the collar 441 guides the filter module 300 to a position around the second support 408. The collar 441 is annular in the illustrated embodiment and can be described as a guide ring. The collar 441 extends completely around the periphery of the filter module 300 in the illustrated embodiment.

[0375] In the illustrated embodiment, the base 438 includes a plurality of ports 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 to 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 are all disposed at the end opposite to the upper surface 418. In other embodiments, the number of ports may be greater or less. Similarly, in other embodiments, one or more male connectors may replace the female connectors 442, 444, 446 on the base 438. For the sake of completeness, Fig. 9 Only the first port 448 of the filter module 300 is marked, and the second and third ports are shown in FIG. Fig. 9 Not visible in.

[0376] 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 implies, when the filter module 300 is inserted (e.g., in the negative x-direction), the female connector receives the male connector. In other embodiments, one or more corresponding female connectors can replace the male connector 448 provided on the filter module 300. That is, Fig. 9 The arrangement of male / female connectors shown in FIG. 4 can be reversed in other embodiments (eg, such that filter module 300 includes a female connector and second support member 408 includes a male connector).

[0377] Optionally, each of the three female connectors 442, 444, 446 of the second support 408 has a different axial extension. In other words, each of the female connectors 442, 444, 446 can have a different axial length. This is found to be advantageous when removing the filter module 300, because the filter module 300 is more gradually disengaged from the second support 408 than an arrangement in which all female connectors 442, 444, 446 are of the same length and the filter module 300 is therefore disconnected from all female connectors at the same time. As mentioned above, this arrangement can also be incorporated as part of the filter module 300 rather than as part of the second support 408.

[0378] The method of 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 member 408. The second support member 408 is pushed away from the first support member 406, thereby defining an open volume (e.g., a filter receiving volume) in which the filter module 300 can be received. The filter module 300 is then received by the second support member 408 so that the port 448 of the filter module 300 is received by the corresponding female connector 442, 444, 446 of the second support member 408. In addition, the support member 440 also guides the filter module 300 to the correct position by abutting against the filter module 300. The combination of the filter module 300 and the second support member 408 is then pushed toward the first support member 406 by rotating about the rotation axis 410 (e.g., about the direction 412 and about the z-axis). As the second support member 408 and the filter module 300 are pushed toward the first support member 406, the upper surface 418 of the filter module 300 gradually overlaps (e.g., covers) the flange 414 of the first support member 406 to an increasing extent. In other words, an increasing range of the upper surface 418 of the filter module 300 is covered by the flange 414. At the same time, the protrusion 422 of the filter module 300 first contacts the first end 428 of the tapered engagement surface 424 of the clip 416. The protrusion 422 elastically deforms the clip 416 due to the increased thickness of the clip 416 along the tapered surface 424, pushing the clip 416 away from the upper surface 418 (e.g., in the x-direction). When the protrusion 422 extends past the second end 428 of the tapered engagement surface 424, the protrusion 422 is received by the recess 430. As shown in FIG. Fig. 9 , which represents a locked configuration in which the filter module 300 is retained by the filter retaining mechanism 402 .

[0379] An advantage of the present invention is that a retaining mechanism is provided that both easily retains the filter module 300 in an operating state and also provides a low force release mechanism by which the filter module 300 can be subsequently removed when maintenance or repair is required. As briefly mentioned above, during operation, the filter module 300 is pushed in direction 420 (e.g., in the x-direction) by the relatively high pressure fluid flow through the filter (through ports and connectors 442, 444, 446, 448). Therefore, it is necessary to retain the filter module 300 to protect the filter module 300 from being ejected due to fluid pressure. The challenge is that while the filter module 300 must be securely retained, it is also necessary to intermittently remove the filter module 300 in order to replace the filter for routine maintenance. The present invention overcomes these problems by effectively providing a two-step retaining mechanism using flange 414 and clip 416.

[0380] The flange 414 provides generally axial retention by at least providing a stop function (e.g., preventing the filter module 300 from popping out in the direction 420 / x direction), and in some embodiments may abut against the upper surface 418. The flange 414 may be described as preventing the filter module 300 from moving to a point where the filter module 300 is disconnected from the plurality of ports in the second support 408. As previously described, the generally arcuate upper surface 418 of the filter module 300 may also create problems because the filter module 300 is pushed or pried off the first support 406 in a direction that may cause the filter module 300 to pop out or disconnect from the first support 406. This is due to the interaction between the domed upper surface 418 and the flat flange 414. The inventors have found that combining a single retention feature (such as the flange 414) does not provide sufficient retention force for the filter module 300 during operation. By advantageously incorporating a second retaining feature (e.g., in the form of a clip 416), the filter module 300 is effectively secured in place and the upper surface 418 is substantially prevented from pushing the filter module 300 away from the first support 406 (because the second retaining feature rotationally locks the second support 408 relative to the first support 406).

[0381] Furthermore, the clip 416 seeks to effectively rotationally latch the first and second supports 406, 408 together in a direction different from the push direction 420 in which the filter module 300 is pushed in operation. Thus, the clip 416 can be easily removed by an operator, and the second support 408 and the filter module 300 can be pivoted away from the first support 406, thereby allowing the filter module 300 to be easily removed from the filter retaining mechanism 402. Thus, the present invention advantageously provides generally axial retention of the filter module 300 (e.g., in the negative x-direction) by the flange 414, and also provides a rotational latch in a different direction (e.g., about the x-axis) that secures the first and second supports 406, 408 together, which can be easily released when it is necessary to provide access to the filter module 300.

[0382] Another advantage is that due to the tapered engagement surface 424 of the clip 416, when the filter module 300 (and the second support member 408) are rotated to Fig. 9 , the clip 416 is effectively automatically engaged with the protrusion 422 of the filter module 300. Thus, when the mechanism transitions from the unlocked configuration to Fig. 9 4, the clip 416 latches the retaining mechanism 402 in the locked configuration. Thus, when the second support 408 is pushed or rotated toward the first support 406, the clip 416 latches the mechanism 402 in the locked configuration. Thus, the retaining direction of the clip 416 is substantially perpendicular to the direction 420 in which the filter module 300 is pushed during use.

[0383] Optionally, the holding mechanism 402 further includes a pop-up mechanism ( Fig. 9 The filter module 300 is provided with a plurality of support members 408 (not visible in the figure), which is used to eject the filter module 300 from the filter retaining mechanism 402 (for example, in the x-direction). It will be appreciated that in use, the filter module 300 may become somewhat stuck when connected to the second support member 408. The ejection mechanism helps to remove the filter module 300, for example after prolonged use. The ejection mechanism can take the form of a lever, which increases the force applied by the operator to remove the filter module 300 by mechanical advantage. Alternatively, a screw arrangement can be used, in which the filter module 300 is pushed away from the second support member 408. It will be appreciated that a variety of other ejection mechanisms can be used in addition. The ejection mechanism can be described as a filter ejection mechanism. The ejection mechanism can reduce the force required by the operator (to eject or remove the filter) to approximately 70N.

[0384] Go to Fig.10 , provides Fig. 9 A cross-sectional side view of assembly 400 is shown in FIG. Fig.10 Many of the features shown in have been combined Fig. 9 A description has been given, and therefore, for the sake of brevity, the description will not be repeated here.

[0385] Fig.10 The filter module 300 is shown having a third port 452 received by the third female connector 446 of the second body 408 . Fig.10 Various features of the first support 406 are also shown, including the flange 414 and the clip 416 (including the cutout 432). Fig.10 A small gap (eg, a clearance) 419 is indicated between the upper surface 418 of the filter module 300 and the flange 414. When the filter 300 and the second support 408 are rotated relative to the first support 406 Fig.10 In the locked configuration shown in FIG. 4 , gap 419 provides clearance. In use, filter module 300 is pushed outwardly by pressurized fluid flowing therethrough, which pushes filter module 300 into engagement with flange 414 .

[0386] Fig.10 Also shown is the relative alignment of the protrusion 422 of the filter module 300 with the recess 430 of the clip 416. Also shown is the curved nature of the upper surface 418 of the filter module 300. Also shown is the alignment feature 456 of the first body 406. When the retaining mechanism 402 is in the locked configuration, the protrusion 422 of the filter module 300 is located between the alignment body 456 and the second end 428 of the tapered engagement surface 424.

[0387] Also shown is an opening 454 in the first body 406 , wherein a portion of the filter module 300 is partially received therethrough in the area labeled 458 .

[0388] Fig.10 Also shown is collar 441 including cutout 443. Cutout 443 allows the magnet of filter module 300 to be placed closer to the sensor, which will combine Fig.11 Describe in detail.

[0389] See also Fig.11 , provides Fig. 9 and 10 4. A rear view of the assembly 400 is shown in FIG. The rear view shows more details of the first support member 406. For example, the opening 454 in the first support member 406 is shown.

[0390] Fig.11 The retaining mechanism 402 is shown to include a sensor 460, which in the illustrated embodiment is a magnetic sensor (eg, a Hall Effect sensor). The sensor 460 is used to detect that the filter module 300 is properly seated in at least Fig.11 406. In other words, the sensor 460 determines that the position of the filter module 300 relative to the second support 408 is correct, and also determines 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 disposed on the filter module 300. The sensor 460 is advantageous over alternative detection mechanisms because in addition to detecting the position of the second support 408 relative to the first support 406, the sensor 460 can also detect the presence of the filter module 300.

[0391] Fig.12 is a perspective view of assembly 400'. Assembly 400' corresponds to assembly 400 shown in the previous figures, except for some minor differences (which will be described below).

[0392] Fig.12 4. The assembly 400' is shown in the unlocked configuration. Thus, the filter module 300' can be received by the second support 408 in the position shown. The second support 408 is shown rotated about the rotation axis 410 away from the first support 406'.

[0393] Filter module 300' differs from filter module 300 in that protrusion 422' of filter module 300' includes holes 423', 425'. Holes 423', 425' provide openings through which an operator can grasp and manipulate filter module 300'.

[0394] Different from the first support member 406, Fig.12 The first support member 406 ′ shown in FIG. 4 does not include the opening 454 .

[0395] Fig.13 is a perspective view of the filter module retaining mechanism 402' in an unlocked configuration. Fig.13 Shows Fig.12 The component 400' in FIG. 4 does not include the filter module 300'.

[0396] Fig.13 A second support 408 is shown including a collar 441 coupled to a support member 440. The second support 408 also 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 filtration module.

[0397] The term retention as used herein includes active engagement (e.g., abutment) and retention by a stopper / buffer that prevents a member (e.g., a filter module) from moving past a retention feature (e.g., Thus, retention does not require active contact, but may include active contact.

[0398] The upper surface of the filter module may be additionally described as an outer surface.The upper surface of the filter module may be additionally described as a surface of the filter module opposite one or more ports (eg, connectors) of the filter module.

[0399] Various modifications and alternatives may be provided to the above-described embodiments. For example, although the above-described filter modules are described in the context of a continuous inkjet printer, they may also be provided separately. Such a filter module may be provided as a removable module for an inkjet printer. It will also be understood that, although a particular form of ink system and a continuous inkjet printer are described, the filter may be applied to different printer configurations. For example, the filter may be used in systems using non-pigmented inks or soft pigmented inks. Similarly, although an electrostatic deflection device using two deflection electrodes to deflect a single ink droplet jet is described, different forms of deflection may be preferred, such as using different numbers of deflection electrodes and / or different numbers of droplet streams. Similarly, the filter may be used in printers that do not require the production of a continuous ink jet.

[0400] The above examples are intended to be illustrative in nature and are not intended to limit or define the scope of protection. The scope of protection is defined by the claims.

[0401] In addition to or as an alternative to the above, the following examples are described. Features described in any of the following examples may be used with any other examples described herein.

[0402] Example 1: A filter module for filtering ink, the filter module comprising: a filter housing, which defines: a filter chamber; an inlet port; a first outlet port; and a second outlet port; a first filter element, which includes a first filter medium arranged in the filter chamber; wherein: the filter housing is configured to define a first filtrate path from the inlet port via the first filter element to the first outlet port, and a second path from the first inlet port across the outer surface of the first filter element to the second outlet port; and when in use, the first outlet port and the second outlet port are arranged vertically above the inlet port.

[0403] Example 2: The filter module according to Example 1, further comprising a second filter element comprising a second filter medium disposed in the filter housing, the second path being a second filtrate path from the inlet port via the second filter medium to the second outlet port.

[0404] Example 3: The filter module of 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.

[0405] Example 4: The filter module of any preceding example, wherein the filter housing is configured to define a third filtrate path from the inlet port via the first filter media to the second outlet port.

[0406] Example 5: The filter module according to Example 4, wherein the third filtrate path passes through the first filter element for a first time to a central cavity surrounded by the first filter element, and then passes through the first filter element for a second time to an outer cavity surrounding the first filter element.

[0407] Example 6: A filter module according to any preceding example, wherein, in use, the filter is arranged to cause ink to flow in a generally upward direction from the inlet to the first and second outlet ports.

[0408] Example 7: A filtration module according to any preceding example, wherein, in use, the second outlet port is arranged vertically above the first outlet port.

[0409] Example 8: A filtration module according to any preceding example, wherein, in use: flow of ink along the first filtrate path is in a direction substantially opposite to that of gravity; and / or flow of ink along the second path is in a direction substantially opposite to that of gravity.

[0410] Example 9: The filtration module of any preceding example, wherein the second path comprises a path defined between an outer surface of the first filter element and a wall of the filter housing defining the chamber.

[0411] Example 10 The filter module of Example 3 or any preceding example dependent therefrom, wherein the absolute rating of the second filter medium is greater than the absolute rating of the first filter element.

[0412] Example 11: The filter module of Example 3 or any preceding example dependent therefrom, wherein an effective surface area of ​​the first filter element is greater than an effective surface area of ​​the second filter element.

[0413] Example 12: The filtration module of any preceding example, wherein the first filter media is a pleated filter media.

[0414] Example 13: The filter module of Example 12, wherein the first filter element comprises a pleat protection filter at least partially covering the pleated filter media.

[0415] Example 14: The filter module of example 12 or 13, wherein the first filter element comprises an output screen disposed between the pleated filter media and the first output port.

[0416] Example 15: The filter module of Example 14, wherein the absolute rating of the first filter element is defined by an output screen.

[0417] Example 16: The filter module of any preceding example, wherein the first filter element defines a central cavity, and the first filter element includes a central support structure disposed within the central cavity.

[0418] Example 17: The filter module of Example 11 or any preceding example dependent therefrom, wherein the nominal rating of the first filter element is defined by a pleated filter media.

[0419] Example 18: The filtration module of any preceding example, wherein the first filter element is substantially cylindrical.

[0420] Example 19: The filtration module of any preceding example, wherein the inlet port, the first outlet port, and the second outlet port are arranged on a single face of the filter housing.

[0421] Example 20: A filtration module according to any preceding example, wherein, in use, an ink flow rate through the second outlet port is greater than an ink flow rate through the first outlet port.

[0422] Example 21: The filtration module of 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.

[0423] Example 22: The filter module according to any preceding example, wherein the filter module further comprises a removal handle.

[0424] Example 23: The filter module according to any preceding example, wherein the filter module further comprises an engagement structure for engaging with a complementary structure of the printer to secure the filter module in the installed configuration.

[0425] Example 24: A continuous inkjet printer comprising an ink circuit, the ink circuit comprising 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 for delivery along at least one of a first filtrate path and a second path.

[0426] Example 25: A continuous inkjet printer according to example 24, wherein, in use, the filter module is arranged to pump ink away from the inlet port in a generally upward direction.

[0427] Example 26: The continuous inkjet printer of Example 24 or Example 25, further comprising a pressure sensor configured to sense a pressure drop across the first filter element.

[0428] Example 27: The continuous inkjet printer of any of Examples 24 to 26 when dependent upon at least Example 2, further comprising a pressure sensor configured to sense a pressure drop across the second filter element.

[0429] Example 28: A filter housing of 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; wherein: 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 via the received first filter element to the first outlet port, and a second path from the first inlet port across the outer surface of the received first filter element to the second outlet port; and when in use, the first outlet port and the second outlet port are arranged vertically above the inlet port.

[0430] Example 29: A method for manufacturing a filter module for filtering ink according to any one of Examples 1 to 23, the method comprising: placing a second filter element including a second filter medium having a second absolute rating in a second outlet port defined by a filter housing, the filter housing also defining an inlet port, a first outlet port and a filter chamber; and placing a first filter element including a first filter medium having a first absolute rating in the filter chamber.

[0431] Example 30: The method of Example 29 further includes forming a first filter element, the forming comprising: forming a pleated filter medium having a central cavity; securing a first closure member to a first end of the filter medium; and securing a second closure member to a second end of the filter medium opposite the first end.

[0432] Example 31: The method of Example 30, wherein, prior to securing the first and second closure members, the method includes: disposing a central support structure in the central cavity; and surrounding an outer face of the pleated filter media with a pleated protective filter.

[0433] Example 32: The method of Example 31, further comprising heat welding the first closure member and the second closure member to the pleated filter media.

[0434] Example 33: A method according to any of Examples 30 to 32, wherein: 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 also includes, after placing the first filter element in the filter chamber, joining the two parts of the filter housing together by spin welding.

[0435] Example 34: A method for filtering ink, the method comprising: pumping ink into a filter chamber defined by a filter housing through an inlet port; filtering a first portion of the ink flowing along a first filtrate path through a first filter element disposed in the filter chamber, the filtrate flowing out of the filter chamber through a first outlet port; allowing a second portion of the ink to flow along a second path, the second path being transmitted across an outer surface of the first filter element to a second outlet port; wherein, when flowing along the first filtrate path and the second path, the flow direction of the ink includes a component in a direction opposite to gravity.

[0436] Example 35: The method of Example 34, further comprising filtering the second portion of the ink through a second filter.

[0437] Example 36: The method of Example 35, wherein flowing the second portion of the ink along the second path includes filtering through a second filter disposed in the second outlet port.

[0438] Example 37: The method of Example 35 or 36, wherein: filtering through a first filter element includes filtering a first portion of the ink to remove particles larger than a first predetermined size; and filtering through a second filter element includes filtering a second portion of the ink to remove particles larger than a second predetermined size, the second predetermined size being larger than the first predetermined size.

[0439] Example 38: A method of operating a continuous inkjet printer, comprising the method of filtering ink according to any 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 inkjet printer.

[0440] Example 39: The method of operating a continuous inkjet printer according to Example 38, further comprising pumping a second portion of the ink from the second outlet port to the venturi pump.

[0441] Example 40: The method of operating a continuous inkjet printer according to Example 38 or 39, further comprising pumping a second portion of the ink from the second outlet port to an ink tank of the continuous inkjet printer.

[0442] Example 41: A filter module holding mechanism for holding a filter module of a continuous inkjet printer, comprising: a first support member; and a second support member pivotally connected to the first support member; wherein the filter module can be received by at least one of the first and second supports in an unlocked configuration, wherein the second support member is at the distal end of the first support member; wherein at least one of the first and second supports includes a first holding feature, the first holding feature being configured to hold the filter module in a locked configuration, in which the second support member is proximate to the first support member to hold the filter module; and wherein at least one of the first and second supports includes a second holding feature, the second holding feature being configured to latch the mechanism in a locked configuration and substantially prevent the second support member from rotating relative to the first support member.

[0443] Example 42: The filter module retaining mechanism of Example 41, wherein the second retaining feature is a clip.

[0444] Example 43: The filter module retention mechanism of Example 42, wherein the clip comprises a tapered engagement surface.

[0445] Example 44: The filter module retaining mechanism of any of Examples 41 to 43, wherein when the filter module retaining mechanism transitions from the unlocked configuration to the locked configuration, the second retaining feature latches the mechanism in the locked configuration.

[0446] Example 45: The filter module retention mechanism of Example 44, wherein the second retention feature latches the mechanism in the locked configuration when the second support is rotated toward the first support.

[0447] Example 46: The filtration module retaining mechanism of any of Examples 41 to 45, wherein the first retaining feature comprises a flange of the first support.

[0448] Example 47: The filtration module retaining mechanism of any of Examples 41 to 46, wherein at least one of the first and second supports by which the filtration module is receivable further comprises a plurality of ports for connecting to corresponding ports of the filtration module.

[0449] Example 48: The filter module retaining mechanism of Example 47, wherein the plurality of ports comprises a plurality of female connectors.

[0450] Example 49: The filter module retaining mechanism of any of Examples 41 to 48, wherein, in use, the retaining force exerted by the first retaining feature is in a first direction and the retaining force exerted by the second retaining feature is in a second direction different from the first direction.

[0451] Example 50: The filter module retaining 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 wherein the other of the first and second supports includes a sensor configured to detect the filter module at least in the locked configuration.

[0452] Example 51: The filter module retaining mechanism of any of Examples 41 to 50, further comprising an ejection mechanism for ejecting the filter module from the filter module retaining mechanism.

[0453] Example 52: The filter module retaining mechanism of any of Examples 41 to 51, wherein the second support is configured to receive the filter module in an unlocked configuration, and wherein the first support is a fixed support configured to retain the filter module in a locked configuration.

[0454] Example 53: The filter module retaining mechanism of Example 52, wherein the first support member includes a second retaining feature.

[0455] Example 54: A component for a continuous inkjet printer, comprising: a filter module holding mechanism according to any of Examples 41 to 53; and a filter module held by the filter module holding mechanism.

[0456] Example 55: The assembly of Example 54, wherein the second retaining feature engages a protrusion of the filter module in the locked configuration.

[0457] Example 56: A continuous inkjet printer comprising the components of Example 54 or 55.

[0458] Example 57: The continuous inkjet printer of Example 56, wherein the filter module is a filter module according to any of Examples 1 to 23.

[0459] Example 58: A method for securing a filter module in a filter module retaining mechanism of a continuous inkjet printer, comprising: pushing the filter module retaining mechanism into an unlocked configuration, wherein a second support member is at a distal end of a first support member; 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; pushing the filter module retaining mechanism into a locked configuration by rotating the second support member toward the first support member, wherein the second support member is proximate to the first support member and the filter module is retained by a first retaining feature of one of the first and second supports, and a second retaining feature of one of the first and second supports is engaged to latch the mechanism in a locked configuration and substantially prevent the second support member from rotating relative to the first support member.

[0460] Example 59: The method of Example 56, wherein placing the filter module in engagement with one of the first and second support members includes placing the filter module in engagement with the second support member; and wherein pushing the filter module retaining mechanism into a locked configuration includes aligning a first retaining feature of the first support member with the filter module to retain the filter module, and pushing the second retaining feature of the first support member into engagement to latch the mechanism in the locked configuration.

[0461] Example 60: The method of Example 58 or 59, wherein the second retaining feature engages the filter module.

[0462] Example 61: The method of Example 60, wherein the second retaining feature engages a flange of the filter module.

[0463] Example 62: The method of Example 61, wherein engaging the protrusion of the filter module with the second retaining feature comprises pushing a tapered engagement surface of the clip past the protrusion of the filter module to latch the mechanism in the locked configuration.

[0464] Example 63: The method of any 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, the filter module comprising: A filter housing, the filter housing defining: Filter chamber; Entry port; a first outlet port; as well as a second outlet port; a first filter element including a first filter medium disposed in the filter chamber; in: The filter housing is configured to define a first filtrate path from the inlet port via 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; and wherein the inlet port, the first outlet port, and the second outlet port are arranged on a single face of the filter housing; and When in use, the first and second outlet ports are arranged vertically above the inlet port.

2. A filter module for filtering ink, the filter module comprising: A filter housing, the filter housing defining: Filter chamber; Entry port; a first outlet port; as well as a second outlet port; 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; in: The filter housing is configured to define a first filtrate path from the inlet port via 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; and wherein the second path is a second filtrate path from the inlet port via the second filter medium to the second outlet port; and When in use, the first and second outlet ports are arranged vertically above the inlet port.

3. A filter module for filtering ink, the filter module comprising: A filter housing, the filter housing defining: Filter chamber; Entry port; a first outlet port; as well as a second outlet port; a first filter element including a first pleated filter media disposed in the filter chamber, and the first filter element further including an output screen disposed between the pleated filter media and a first output port; in: the filter housing being configured to define a first filtrate path from the inlet port via 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; and When in use, the first and second outlet ports are arranged vertically above the inlet port.

4. A filter module for filtering ink, the filter module comprising: A filter housing, the filter housing defining: Filter chamber; Entry port; a first outlet port; as well as a second outlet port; a first generally cylindrical filter element including a first filter media disposed in the filter chamber; in: the filter housing being configured to define a first filtrate path from the inlet port via 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; and When in use, the first and second outlet ports are arranged vertically above the inlet port.

5. The filter module according to any one of claims 2 to 4, wherein: The inlet port, the first outlet port, and the second outlet port are arranged on a single face of the filter housing.

6. The filter module according to claim 1, 3 or 4, further comprising a second filter element, the second filter element comprising a second filter medium disposed in the filter housing, the second path being a second filtrate path from the inlet port via the second filter medium to the second outlet port.

7. The filtration module according to claim 1, 2 or 4, wherein: The first filter media is a pleated filter media, and the first filter element includes an output screen disposed between the pleated filter media and a first output port.

8. The filtration module according to any one of claims 1 to 3, wherein: The first filter element is generally cylindrical.

9. The filtration module according to 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 different from the first absolute rating.

10. A filtration module according to any preceding claim, wherein The filter housing is configured to define a third filtrate path from the inlet port via the first filter media to the second outlet port.

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

13. A filtration module according to any preceding claim, wherein: In use, the second outlet port is arranged vertically above the first outlet port.

14. A filtration module according to any preceding claim, wherein In use: The flow of ink along the first filtrate path is in a direction substantially opposite to the direction in which gravity acts; and / or The flow of ink along the second path is in a direction substantially opposite to the direction in which gravity acts.

15. A filtration module according to any preceding claim, wherein The second path includes a path defined between an outer surface of the first filter element and a wall of the filter housing defining the chamber.

16. A filtration module according to claim 9 or any preceding claim as appended thereto, wherein: The absolute rating of the second filter medium is greater than the absolute rating of the first filter element.

17. A filtration module according to claim 9 or any preceding claim as appended thereto, wherein: The effective surface area of ​​the first filter element is greater than the effective surface area of ​​the second filter element.

18. The filtration module according to claim 3 or claim 7, wherein: The first filter element includes a pleat protection filter at least partially covering the pleated filter media.

19. The filtration module according to claim 3 or claim 7, wherein: The absolute rating of the first filter element is defined by the output screen.

20. A filtration module according to any preceding claim, wherein The first filter element defines a central cavity, and the first filter element includes a central support structure disposed within the central cavity.

21. A filtration module according to claim 17 or any preceding claim as appended thereto, wherein: The nominal rating of the first filter element is defined by the pleated filter media.

22. A filter module according to any preceding claim, 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. A filtration module according to any preceding claim, wherein: The filter module also includes a removal handle.

24. A filtration module according to any preceding claim, wherein The filter module also includes engagement structure for engaging with complementary structure of the printer to secure the filter module in the installed configuration.

25. A continuous inkjet printer comprising an ink circuit comprising an ink tank, an ink pump arrangement and a filter module according to any preceding claim for filtering ink; in, The ink pump is configured to pump ink from the ink tank through the first inlet port for delivery along at least one of the first filtrate path and a second path.

26. The continuous inkjet printer of claim 25, wherein: In use, the filter module is arranged to pump ink away from the inlet port in a generally upward direction.

27. A continuous inkjet 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. A continuous inkjet 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 arranged to sense the pressure drop across the second filter element.

29. A filter housing for a filter module, the filter module being used to filter ink, the filter housing defining: Filter chamber; Entry port; a first outlet port; as well as a second outlet port; in: The filter chamber is configured to receive a first filter element; the filter housing being configured to define a first filtrate path from the inlet port via the received first filter element to the first outlet port, and a second path from the first inlet port across an outer surface of the received first filter element to the second outlet port; and When in use, the first and second outlet ports are arranged vertically above the inlet port.

30. A method of manufacturing a filter module according to any one of claims 1 to 24 for filtering ink, the method 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, the filter housing also defining an inlet port, a first outlet port, and a filter chamber; as well as A first filter element including a first filter media having a first absolute rating is placed in the filter housing.

31. The method of claim 30, further comprising forming the first filter element, the forming comprising: forming a pleated filter medium having a central cavity; securing a first closure member to a first end of the filter medium; as well as A second closure is secured to a second end of the filter media opposite the first end.

32. The method according to claim 31, wherein: Before fixing the first closure member and the second closure member, the method includes: Disposing a central support structure within the central cavity; and A pleat guard filter surrounds the exterior face of the pleated filter media.

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

34. A method according to any one of claims 31 to 33, wherein: the first filter element comprising an outlet port engagement arrangement, and placing the first filter element in the main chamber comprises engaging the engagement arrangement with the first outlet port; and / or The method also includes joining the two portions of the filter housing together by spin welding after placing the first filter element in the filter chamber.

35. A method for filtering ink, the method 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 through a first filter element disposed in the filtration chamber, the filtrate flowing out of the filtration chamber through a first outlet port; causing a second portion of the ink to flow along a second path that passes across an exterior surface of the first filter element to a second outlet port; Wherein, when flowing along the first filtrate path and the second path, the flow direction of the ink includes a component in a direction opposite to gravity.

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

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

38. The method of claim 36 or 37, wherein: Filtering through the first filter element includes filtering the first portion of the ink to remove particles larger than a first predetermined size; as well as Filtering through the second filter element includes filtering the second portion of the ink to remove particles larger than a second predetermined size, the second predetermined size being larger than the first predetermined size.

39. A method of operating a continuous inkjet printer, the method comprising the method of any one of claims 35 to 38 of filtering ink, further comprising pumping a first portion of the ink from the first outlet port to a print head of the continuous inkjet printer.

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

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

42. A filter module holding mechanism for holding a filter module for a continuous inkjet printer, comprising: a first support member; as well as a second support member pivotally connected to the first support member; wherein the filter module is receivable by at least one of the first support member and the second support member in an unlocked configuration, wherein the second support member is distal to the first support member in the unlocked configuration; wherein at least one of the first support and the second support comprises a first retaining 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 Wherein at least one of the first support and the second support includes a second retaining feature configured to latch the mechanism and substantially prevent the second support from rotating relative to the first support in the locked configuration.

43. The filter module holding mechanism according to claim 42, wherein: The second retaining feature is a clip.

44. The filter module holding mechanism according to claim 43, wherein: The clip includes a tapered engagement surface.

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

46. ​​The filter module retaining mechanism according to claim 45, wherein: The second retaining feature latches the mechanism in the locked configuration when the second support is rotated toward the first support.

47. The filter module holding mechanism according to any one of claims 42 to 46, wherein: The first retaining feature comprises a flange of the first support.

48. The filter module holding mechanism according to any one of claims 42 to 47, wherein: The at least one of the first support and the second support by which the filter module can be received further comprises a plurality of ports for connecting to corresponding ports of the filter module; and optionally, Wherein, the plurality of ports include a plurality of female connectors.

49. The filter module retaining mechanism according to any one of claims 42 to 48, wherein: In use, the retaining force exerted by the first retaining feature is in a first direction, and wherein the retaining force exerted by the second retaining feature is in a second direction different from the first direction.

50. The filter module retaining mechanism according to any one of claims 42 to 49, wherein: In the unlocked configuration, the filter module may be received by one of the first support and the second support, and wherein the other of the first support and the second support comprises a sensor configured to detect the filter module in at least the locked configuration.

51. The filter module holding mechanism according to any one of claims 42 to 50, further comprising an ejection mechanism for ejecting the filter module from the filter module holding mechanism.

52. The filter module retaining mechanism according to any one of claims 42 to 51, wherein: The second support is configured to receive the filter module in an unlocked configuration, and wherein the first support is a fixed support configured to hold the filter module in a locked configuration.

53. The filter module retaining mechanism according to claim 52, wherein: The first support includes the second retaining feature.

54. An assembly for a continuous inkjet printer, comprising: The filter module holding mechanism according to any one of claims 42 to 53; as well as A filter module is held by the filter module holding mechanism.

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

56. A continuous inkjet printer comprising an assembly according to claim 54 or 55.

57. A continuous inkjet printer according to claim 56, wherein: The filter module is a filter module according to any one of claims 1 to 24.

58. A method for fixing a filter module in a filter module holding mechanism of a continuous inkjet printer, comprising: Pushing the filter module retaining mechanism into an unlocked configuration, in which the second support member is distal to the first support member; placing the filter module into engagement with one of the first support and the second support such that the filter module is received by one of the first support and the second support; The filter module retaining mechanism is pushed into a locked configuration by rotating the second support member toward the first support member, in which the second support member is close to the first support member, and the filter module is retained by a first retaining feature of one of the first support member and the second support member, and a second retaining feature of one of the first support member and the second support member is engaged to latch the mechanism in the locked configuration and substantially prevent the second support member from rotating relative to the first support member.

59. The method of claim 56, wherein: placing the filter module in engagement with one of the first support and the second support comprises placing the filter module in engagement with the second support; and Wherein, pushing the filter module retaining mechanism into the locked configuration includes: aligning the first retaining feature of the first support member with the filter module to retain the filter module, and pushing the second retaining feature of the first support member to engage to latch the mechanism in the locked configuration.

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

61. The method of claim 60, wherein: The second retaining feature engages with a protrusion of the filter module.

62. The method of claim 61, wherein: Engaging the protrusion of the filter module with the second retaining feature includes pushing a tapered engagement surface of a clip past the protrusion of the filter module to latch the mechanism in the locked configuration.

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 locked configuration.

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